JP7633800B2 - Tatami mat - Google Patents

Description

The present invention relates to tatami coverings.

Tatami mats, which are widely used as flooring in Japanese houses, are made by laminating a tatami surface onto the surface of a tatami floor. Tatami surface mats are made by weaving natural rush as the weft and cotton or hemp thread as the warp using a hikime weave or meseki weave method, but natural rush has drawbacks such as being prone to pests, having low mechanical strength, being expensive, and being in limited supply.

Recently, therefore, artificial rushes made from paper or various thermoplastic resin films have been proposed (see, for example, Patent Documents 1, 2, and 3). These artificial rushes are industrial products made from paper and plastic resin, and therefore have the advantages of being pest-free, low-cost, stable in supply, and excellent mechanical strength and cushioning. Furthermore, artificial rushes have been proposed that have been coated with functional substances such as anti-mite agents, anti-fungal agents, deodorants, antibacterial agents, flame retardants, VOC adsorbents, far-infrared emitters, and negative ion emitters to improve their functionality (see, for example, Patent Document 4).

However, cotton and hemp threads are still used as warp threads. These warp threads have excellent water absorption and water retention, and tatami mats made of artificial rush woven from thermoplastic resin as weft threads have excellent water absorption and water retention properties as tatami mats, despite the use of artificial rush, which has low water absorption and water retention properties. Therefore, if miso soup, coffee, etc. is spilled on the tatami mat, it cannot be easily wiped off, and it remains on the surface of the tatami mat for a long time or leaves a stain, which is a drawback in that it has low cleanability and stain resistance.

In addition, since tatami mats are a building material for houses, there has been a recent demand for better flame retardancy, flame resistance that allows fires to be extinguished quickly even if they catch fire, antibacterial properties, etc.

Japanese Patent Application Publication No. 8-170422 JP 2014-95187 A Japanese Patent Application Publication No. 1-92443 JP 2005-282152 A

In view of the above problems, the object of the present invention is to provide a tatami surface that is excellent in cleanability and stain resistance. Another object is to provide a tatami surface that is excellent in flame retardancy, flame resistance that allows fire to be extinguished in a short time even if it catches fire, antibacterial properties, etc.

That is, the present invention provides:
[1] A tatami mat lining characterized by being woven using a resin-based twisted yarn formed by twisting 2 to 10 thermoplastic resin single fibers having a denier of 300 to 2000 as a warp thread and igusa as a weft thread.
[2] The tatami mat according to the above [1], characterized in that the thermoplastic resin is a polypropylene-based resin or a polyester-based resin.
[3] The tatami mat according to [1] or [2] above, characterized in that a flame retardant and/or an antibacterial agent is further kneaded into the thermoplastic resin monofilament;
[4] The tatami mat according to any one of the above [1] to [3], characterized in that the rush is artificial rush.
[5] The tatami covering described in [4] above, characterized in that the artificial rush is obtained by bundling uniaxially oriented films made of olefin resin and inorganic filler into a string shape, and passing the resulting bundle through a gap in a heating element having a gap narrower than the diameter of the bundle, thereby irregularly and partially fusing and binding the uniaxially oriented films of the bundle and forming a fused coating on the surface of the bundle; and
[6] The tatami covering according to the above [5], further comprising a flame retardant and/or an antibacterial agent kneaded into the uniaxially stretched film.

The tatami mat of the present invention has the above-mentioned structure, and is excellent in cleanliness and stain resistance. It also has excellent flame retardancy, flame resistance that allows fire to be extinguished in a short time even if it catches fire, antibacterial properties, etc.

The tatami mat of the present invention is characterized by being woven using resin-based twisted yarns made by twisting 2 to 10 thermoplastic resin monofilaments having a denier of 300 to 2000 as the warp yarns and rush as the weft yarns.

The above thermoplastic resin can be any resin having thermoplastic properties, for example, polypropylene resins such as ethylene-propylene copolymers, high-density polyethylene resins, medium-density polyethylene resins, low-density polyethylene resins, linear low-density polyethylene resins, ethylene-1-butene copolymers, ethylene-1-pentene copolymers, ethylene-1-hexene copolymers, and other olefin resins, polyester resins, acrylic resins, urethane resins, etc., with polypropylene resins and polyester resins being preferred.

The resin twisted yarn is a resin twisted yarn made by twisting thermoplastic resin monofilaments, and the thermoplastic resin monofilaments are simply thread-like fibers formed by extrusion molding of thermoplastic resin. If the thickness of the thermoplastic resin monofilaments is thin, they will absorb and retain more water when twisted, and if miso soup, coffee, or the like is spilled and left for a long time, it will soak into the resin twisted yarn and will not be easy to wipe off, resulting in poor cleanability and stain resistance. Also, if the thickness is thick, it will be difficult to twist and the twisted resin twisted yarn will be thick, making it impossible to use as a warp thread for tatami mats, so the denier is 300 to 2000.

If the number of twisted thermoplastic resin single fibers is small, the mechanical strength will be low, and if the number is large, if miso soup, coffee, etc. is spilled on the twisted resin-based twisted yarn and left for a long time, the spill will soak into the resin-based twisted yarn and it will not be easy to wipe off, and the cleanability and stain resistance will be reduced, and the yarn will become too thick, making it difficult to weave and unable to use as the warp thread for tatami mat facings. Therefore, the number of twisted thermoplastic resin single fibers is 2 to 10, and preferably 3 to 5. There is no particular limit to the thickness of the resin-based twisted yarn, but since it is the warp thread for tatami mat facings, 1000 to 5000 denier is preferable.

The resin-based twisted yarn formed by twisting the above-mentioned thermoplastic resin monofilaments refers to a resin-based twisted yarn formed by twisting only a plurality of thermoplastic resin monofilaments, and does not include mixed twisted yarns formed by mixing and twisting natural yarns such as cotton yarns and linen yarns.

Because tatami mats are building materials for houses, they are preferably flame-retardant and have excellent flame resistance so that even if a fire does catch, the fire can be extinguished in a short time. The tatami mats of the present invention are woven using rush grass as the weft and the above-mentioned resin-based twisted yarn as the warp, so in order to improve the flame resistance and flame resistance of the tatami mats, it is preferable that the warp melts and the weft breaks apart when the tatami mat catches fire or is exposed to high temperatures. This is because if the weft breaks apart, gaps will form between the weft threads, preventing the fire from spreading and allowing the fire to be extinguished.

Therefore, when the resin-based twisted yarn shrinks after melting and cutting or at the same time, gaps are created above and below the cut surface of the resin-based twisted yarn, and the weft yarn located at the cut surface is pulled above and below the cut surface as the resin-based twisted yarn melts and creates gaps above and below. Therefore, it is preferable that the resin-based twisted yarn has heat shrinkability, and the heat shrinkage rate is preferably 3% or more.

The heat shrinkage rate is the shrinkage ratio when the resin twisted yarn is heated in an atmosphere of 60° C. for 6 hours without load, and is calculated by the following formula.
Heat shrinkage rate (%) = (length of resin-based twisted yarn before heating - length of resin-based twisted yarn after heating) x 100 / length of resin-based twisted yarn before heating

Any conventionally known method may be used to impart heat shrinkability to the resin-based twisted yarn, such as uniaxially stretching a thermoplastic resin monofilament before twisting.

In order to improve the flame retardancy of the tatami mat, its flame resistance so that even if it catches fire it can be extinguished in a short time, its antibacterial properties, etc., it is preferable to add a flame retardant and/or an antibacterial agent to the thermoplastic resin monofilament. Also, if the flame retardant and/or antibacterial agent is applied to the surface of the thermoplastic resin monofilament, it will peel off and be removed over time, reducing its effectiveness, so it is preferable to knead it into the thermoplastic resin monofilament.

The flame retardant may be any known flame retardant that has been conventionally used in the molding of thermoplastic resin molded products. Examples of the flame retardant include graphite-based flame retardants, nitrogen-based flame retardants such as melamine-based compounds and guanidine-based compounds, red phosphorus-based flame retardants, phosphorus-based flame retardants such as ammonium phosphate, silicon-based flame retardants, and bromine-based flame retardants, with bromine-based flame retardants being preferred.

As the antibacterial agent, any conventionally known antibacterial agent can be used, for example, inorganic metal ion compounds in which antibacterial metals (e.g., silver, zinc, copper, etc.) or metal ions are supported on an inorganic carrier (e.g., product name "Novalon" manufactured by Toa Gosei Co., Ltd.), nitrile compounds, pyridine compounds, haloalkylthio compounds, organic iodine compounds, thiazole compounds, benzimidazole compounds, wasabi components (allyl isothiocyanate), etc. are listed, and zinc-based metal ion compounds are preferred.

Furthermore, anti-mite agents, anti-fungal agents, deodorants, inorganic fillers, colorants, etc. may be kneaded into the thermoplastic resin monofilaments as necessary.

Examples of the above-mentioned anti-mite agents include pyrethroid compounds, organophosphorus compounds, carbamate compounds, etc., and examples of the above-mentioned anti-mold agents include natural products such as persimmon tannin, wood vinegar, cypress essential oil, Japanese cedar essential oil, wasabi, catechin, wood vinegar, etc., organic compounds such as thiabendazole, diphenyl, orthophenylphenol, and inorganic compounds such as titanium oxide, etc., and examples of the above-mentioned deodorants include carbon materials such as charcoal, bamboo charcoal, activated charcoal, and binchotan charcoal, as well as silica, alumina, zeolite, etc.

Examples of the inorganic fillers include calcium carbonate, magnesium carbonate, aluminum oxide, magnesium oxide, titanium oxide, magnesium hydroxide, talc, mica, clay, etc.

Examples of the colorants include organic pigments such as azo, phthalocyanine, threne, and dye lake pigments, and inorganic pigments such as oxide, molybdenum chromate, sulfide/selenide, and ferrocyanide pigments.

Furthermore, if necessary, antioxidants such as phenol-based antioxidants and aromatic amine-based antioxidants, ultraviolet absorbers such as salicylic acid esters, benzophenones, benzotriazoles, and cyanoacrylates, hindered amine-based light stabilizers, cationic and nonionic antistatic agents, impact modifiers, etc. may be kneaded into the composition.

The rush mentioned above may be natural rush or artificial rush made from paper or thermoplastic resin, but artificial rush obtained by bundling uniaxially stretched film made of olefin resin and inorganic filler into a string shape and passing the resulting bundle through the gap of a heating element having a gap narrower than the diameter of the bundle, thereby irregularly and partially fusing and binding the uniaxially stretched film of the bundle together and forming a fused coating on the surface of the bundle, is preferred.

There are no particular restrictions on the thickness of the rush, but it is generally 0.5 to 5 mm in diameter, with 0.8 to 3 mm being preferable. Furthermore, if artificial rush is dense, it will become heavy and hard, reducing its insulation, impact resistance, shielding properties, etc., so it is preferable for it to have a porosity of 15 to 50%.

The porosity is the volume ratio of air bubbles that are present in the artificial rush. The bubbles may be not only closed bubbles but also open bubbles, and the open bubbles may be connected to the outside of the artificial rush.

The uniaxially stretched film is a resin film made of an olefin resin and an inorganic filler that is uniaxially stretched.

Examples of the olefin resin include high-density polyethylene resin, medium-density polyethylene resin, low-density polyethylene resin, linear low-density polyethylene resin, polypropylene resin, ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-1-pentene copolymer, ethylene-1-hexene copolymer, etc., with high-density polyethylene resin and polypropylene resin being preferred.

Examples of the inorganic fillers include calcium carbonate, magnesium carbonate, aluminum oxide, magnesium oxide, titanium oxide, magnesium hydroxide, talc, mica, clay, etc.

If the resin film contains an inorganic filler, when the resin film is uniaxially stretched, voids are formed in the uniaxially stretched film with the inorganic filler as a nucleus, making the film lighter and improving its heat insulation and cushioning properties, so it is preferable to add 10 to 50 parts by weight of inorganic filler to 100 parts by weight of thermoplastic resin.

In addition, it is preferable to add a flame retardant and/or antibacterial agent to the resin film in order to improve the flame retardancy of the tatami mat, the flame resistance so that even if a fire is started, it can be extinguished in a short time, and the antibacterial properties. If applied to the surface of the thermoplastic resin monofilament, the agent will peel off and be removed over time, reducing its effectiveness, so it is preferable to knead the agent into the resin film.

The flame retardant and antibacterial agent are as described above, and furthermore, the above-mentioned anti-mite agent, anti-fungal agent, deodorizer, colorant, etc. may be kneaded in as necessary.

The resin film can be produced by any conventionally known production method, such as extrusion, T-die, casting, calendaring, inflation, pressing, or other film-forming methods using a resin composition made of the olefin resin and inorganic filler.

The uniaxially stretched film is the resin film uniaxially stretched. Any conventionally known method may be used for the uniaxial stretching, such as roll uniaxial stretching and zone uniaxial stretching.

If the uniaxial stretching temperature is too low, the film will not be stretched uniformly, and if it is too high, the resin film will melt and break, so the temperature is preferably in the range of "melting point - 60°C" to the melting point of the olefin resin in the resin film to be stretched, and more preferably "melting point - 50°C" to "melting point - 5°C" of the olefin resin.

The uniaxial stretching ratio is preferably 2 to 10 times, because a lower ratio reduces the mechanical strength, and a higher ratio makes the material hard and reduces the texture of the rush. The thickness of the uniaxially stretched film is preferably 5 to 20 μm.

The bundle is formed by bundling the uniaxially stretched film into a string. The bundling method is not particularly limited, and examples include a method of folding the uniaxially stretched film along the uniaxial stretching direction and bundling it, a method of twisting narrow uniaxially stretched films into a twisted thread, and a method of combining narrow uniaxially stretched films into a braided string, and the folding and bundling method is preferred.

Next, the bundle is passed through the gap of a heating element having a gap narrower than the diameter of the bundle, causing the uniaxially stretched films to irregularly fuse and converge with each other and form a fused coating on the surface, resulting in artificial rush.

The heating element may be any member capable of heating, narrower than the diameter of the bundle, and having a narrow gap through which the bundle can pass. However, since the uniaxially stretched film is irregularly fused and converged to each other by passing the bundle through the narrow gap, and a fused coating is formed on the surface, it is preferable that the diameter of the gap is 40 to 90% of the diameter of the bundle. The cross-sectional shape of the gap may be approximately the same as the cross-sectional shape of the artificial rush to be obtained, and for example, a circle, ellipse, square, hexagon, octagon, etc. are preferable.

In addition, protrusions may be formed near the exit of the gap so that wrinkles or through holes are formed in the formed fused coating. If through holes are formed in the formed fused coating, the gaps in the fused coating are connected to the outside air, which is preferable as it further improves moisture absorption, heat insulation, etc.

The heating temperature of the heating element is equal to or higher than the melting point of the olefin resin of the uniaxially stretched film, and is preferably between the melting point + 100°C and the melting point + 150°C of the olefin resin, since the bundle is passed through the gap of the heating element to irregularly fuse and bind the uniaxially stretched films together and form a fused coating on the surface.

If the speed at which the bundle is passed through the gap in the heating element is slow, the fusion rate of the uniaxially stretched film will increase, the void ratio will decrease, and the bundle will become heavier and harder. Conversely, if the speed is fast, it will be difficult to form a fused coating on the surface. Although this depends on the heating temperature, a speed of 15 to 75 m/min is generally preferred.

The tatami mat of the present invention is woven using the above-mentioned resin-based twisted yarn as the warp and rush as the weft, but the weaving method is not particularly limited and any conventionally known weaving method can be used, such as hikime weave, meseki weave, plain weave, and twill weave.

In addition, in order to improve the mechanical strength of the tatami facing, adjacent rushes are woven in close contact with each other, and adjacent warp threads are preferably woven at intervals of 2 to 30 mm, as in conventional tatami facings.

Next, we will explain examples of the present invention, but the present invention is not limited to these examples.

A resin composition consisting of a polypropylene resin (density 0.9 g/cm ³ , melting point 155-165° C.), a polyester resin, a bromine-based flame retardant (manufactured by Dainichiseika Chemicals Mfg. Co., Ltd., product name "Daifuunen") and a zinc-based antibacterial agent (manufactured by Toa Gosei Co., Ltd., product name "Novalon") in the prescribed amounts shown in Table 1 was fed to a single-screw kneading extruder and melt-kneaded and extruded at 210° C. to obtain thermoplastic resin single fibers (1), (2), (3) and (4) having the deniers shown in Table 1.

Manufacture of resin twisted yarns Five each of the thermoplastic resin monofilaments (1), (2), (3) and (4) were bundled and twisted to obtain 2500 denier resin twisted yarns (1) and (2) and 5000 denier resin twisted yarns (3) and (4). Also, two resin twisted yarns (1) and three 550 denier cotton yarns were bundled and twisted to obtain a 2650 denier mixed twisted yarn.

Water absorption and water retention test of twisted yarn The above-mentioned resin-based twisted yarns (1) and (4) and the mixed twisted yarn, each having a length of 10 m, were conditioned for at least 2 hours in an atmosphere of 25°C and 50% humidity, and then immersed in water for 1 hour. After immersion, the yarns were taken out and dried in an atmosphere of 25°C and 50% humidity, and the weight of the twisted yarn was measured at each predetermined drying time shown in Table 2, and the results are shown in Table 2. The weight of the twisted yarn before immersion in water was set to 0, and the weight increase rate of the twisted yarn at each predetermined drying time was shown in %.

Heat shrinkage rate The above resin-based twisted yarns (1) and (4) and the mixed twisted yarn having a length of 10 cm were fed into a gear oven set at 60° C. and heated for 6 hours without load to measure the heat shrinkage rate. The results are shown in Table 2.

(Examples 1 to 4, Comparative Examples 1 and 2)
Manufacturing of artificial rush
A resin composition consisting of 100 parts by weight of polypropylene resin (density 0.9 g/cm ³ , melting point 155 to 165°C), 27 parts by weight of calcium carbonate, 2.0 parts by weight of an azo-based inorganic pigment, and the prescribed amounts of a bromine-based flame retardant (manufactured by Dainichiseika Chemicals Mfg. Co., Ltd., product name "Daifuunen") and a zinc-based antibacterial agent (manufactured by Toa Gosei Co., Ltd., product name "Novalon") shown in Table 3 was fed into a single-screw kneading extruder with a 70 mm screw and kneaded and extruded at 210°C to obtain a polypropylene resin film having a thickness of 100 μm.

The obtained polypropylene resin film was fed to a hot plate type uniaxial stretching device set at 120°C and stretched 5 times to obtain a uniaxially stretched film with a thickness of 20 μm. The obtained uniaxially stretched film was folded in the uniaxial stretching direction and passed through a through hole with a diameter of 2.0 mm to obtain a bundle formed into a string shape with a diameter of 2.0 mm. The obtained bundle with a diameter of 2.0 mm was fed to a heating element having a circular cross-sectional gap with a diameter of 1.0 mm, and passed through the gap at a speed of 65 m/min to obtain artificial rush (1), (2), (3) and (4).

The heating element was heated to 300°C, and eight pointed protrusions, 0.05 mm high, were installed at 45° intervals near the exit of the gap. The resulting artificial rush had the tape-shaped body partially fused and a fused coating formed on the surface, with random through-holes and irregularities formed in the fused coating. The resulting artificial rush was black, had a diameter of approximately 1.1 mm, and a porosity of 33%. The mechanical properties of artificial rushes (1), (2), (3), and (4) were measured in accordance with JIS K7127 at a chuck distance of 200 mm and a tensile speed of 300 mm/min. The breaking strength in the longitudinal direction was 9.5-9.8 N, and the breaking elongation was 9-11%.

Manufacturing of Tatami Coverings The specified artificial rush shown in Tables 4 and 5 was used as the weft, twisted yarn was used as the warp, the interval between the warp threads was set to 4 mm, and the weft thread count was set to 90 threads/10 cm. The tatami coverings were obtained by weaving using the specified weaving method shown in Tables 4 and 5.

In Comparative Example 2, natural rush was used as the weft and the resin-based twisted yarn (2) was used as the warp, the interval between the warp threads was set to 4 mm, and the weft thread count was set to 90 threads/10 cm. The tatami mat was woven using a hikime weave method.

The resulting tatami mat was cut into three samples, which were then subjected to a combustion test in accordance with Article 4 of the Fire Service Act Enforcement Regulations (Carpets), measuring the afterflame time and char length, with the results shown in Tables 4 and 5. Those with an afterflame time of 20 seconds or less and a char length of 10 cm or less were given an overall rating of ○, and those with even one point greater than this were given an ×.

In addition, antibacterial properties were evaluated in accordance with JIS Z2801-2012, and antibacterial activity values of 2.0 or more were marked as ◯, and values below that were marked as ×. The results are shown in Tables 4 and 5. The results are shown in Tables 4 and 5.

The tatami mats obtained in Examples 1 and 4 and Comparative Examples 1 and 2 were cut into square samples of 10 x 10 cm, and water absorption and water retention tests were carried out in the same manner as in the water absorption and water retention tests for the twisted yarn, and the results are shown in Table 5.

The tatami mat of the present invention has excellent cleanability and stain resistance, and can be appropriately imparted with flame retardancy, flame resistance that allows fire to be extinguished in a short time even if it catches fire, antibacterial properties, etc., making it suitable for use as a building material.

Claims (5)

The tatami covering is woven using a resin-based twisted yarn formed by twisting 3 to 5 thermoplastic resin single fibers having a denier of 500 to 1000 as a warp yarn and an artificial rush as a weft yarn, and is characterized in that the heat shrinkage rate of the resin-based twisted yarn calculated by the following formula is 3% or more.
The heat shrinkage rate is the shrinkage ratio when the resin twisted yarn is heated in an atmosphere of 60° C. for 6 hours without load.
Heat shrinkage rate (%) = (length of resin-based twisted yarn before heating - length of resin-based twisted yarn after heating) x 100 / (length of resin-based twisted yarn before heating) The tatami mat according to claim 1, characterized in that the thermoplastic resin is a polypropylene-based resin or a polyester-based resin. The tatami mat according to claim 1 or 2, characterized in that a flame retardant and/or an antibacterial agent is kneaded into the thermoplastic resin monofilament. The tatami covering of claim 3 is characterized in that the artificial rush is obtained by bundling uniaxially stretched film made of olefin resin and inorganic filler into a string shape, and passing the resulting bundle through a gap in a heating element having a gap narrower than the diameter of the bundle, thereby irregularly and partially fusing and binding the uniaxially stretched film of the bundle to each other and forming a fused coating on the surface of the bundle. 5. The tatami mat according to claim 4, wherein a flame retardant and/or an antibacterial agent is further kneaded into the uniaxially stretched film.