JP7795406B2 - Architectural interior flooring material and method for manufacturing the same - Google Patents

Description

The present invention relates to a flooring material for architectural interiors that has a colored decorative layer and a method for manufacturing the same.

BACKGROUND ART Conventionally, interior flooring materials for buildings, which have a surface layer containing a vinyl chloride resin and a colored decorative layer of various designs, have been provided on the market.
Such a colored decorative surface layer is generally formed by applying plate printing, such as rotary screen printing or gravure printing, to a resin layer containing a vinyl chloride resin, etc. However, plate printing is suitable for mass printing of the same design, but is not suitable for small-lot printing. In addition, the design formed by plate printing is a repetition of the pattern printed on the roll plate, and the repetition of the design also depends on the circumferential length of the roll plate.
In this regard, plateless printing such as inkjet printing allows for easy production of architectural interior flooring materials with any design, and is also suitable for producing flooring materials in small lots.

Patent Document 1 discloses a flooring material having a printed layer made of inkjet ink. Specifically, Patent Document 1 discloses a flooring material having a layer structure consisting of, from the back side, a base sheet 23 made of vinyl chloride resin, a printed film 25 made of vinyl chloride resin, an ink-receiving layer 6, a printed layer 5 made of inkjet ink, a polyurethane-based hot-melt resin sheet 24, and a transparent surface sheet 22 made of vinyl chloride resin. The polyurethane-based hot-melt resin sheet 24 functions as an adhesive layer, bonding the printed layer 5 and the transparent surface sheet 22 together.

Patent No. 3921382

However, the flooring material in Patent Document 1 uses a polyurethane-based hot melt resin sheet to bond the print layer 5 and the transparent surface sheet 22 together, so if exposed to relatively high temperatures for a long period of time, the hot melt resin may soften and the interlayer peel strength may decrease.

The object of the present invention is to provide an architectural interior flooring material that is resistant to peeling between PVC layers, even when a colored decorative layer is formed between the PVC layers using inkjet ink, and a method for manufacturing the same.

The architectural interior flooring material of the present invention has a surface layer having, in this order: a first PVC layer containing a vinyl chloride resin; a colored decorative layer formed from inkjet ink and containing an ultraviolet-curable resin ; an adhesive layer containing an ultraviolet-curable resin; and a second PVC layer containing a vinyl chloride resin.

In a preferred architectural interior flooring material of the present invention, the ultraviolet-curable resin of the colored decorative layer comprises an acrylic ultraviolet-curable resin, and the ultraviolet-curable resin of the adhesive layer comprises an acrylic ultraviolet-curable resin .
In a preferred architectural interior flooring material of the present invention, the adhesive layer does not contain a pigment.
In a preferred architectural interior flooring material of the present invention, the second PVC layer contains fine particles.
In a preferred architectural interior flooring material of the present invention, the interlayer peel strength between the first PVC layer and the second PVC layer is 30 N/50 mm or more.

According to another aspect of the present invention, there is provided a method for producing an architectural interior flooring material.
The manufacturing method of the present invention comprises the steps of preparing a decorative sheet having a first PVC sheet containing a vinyl chloride resin, a colored decorative layer formed on the first PVC sheet, and an adhesive layer formed on the colored decorative layer, preparing a second PVC sheet containing a vinyl chloride resin, and forming a laminate consisting of first PVC sheet/colored decorative layer/adhesive layer/second PVC sheet by integrating the decorative sheet and second PVC sheet under a heated state, wherein the colored decorative layer is formed by printing inkjet ink containing an ultraviolet-curable resin onto the first PVC sheet using an inkjet printer, and the adhesive layer is formed by applying a coating liquid containing an ultraviolet-curable resin onto the colored decorative layer and curing it.

The architectural interior flooring material of the present invention has a colored decorative layer formed using inkjet ink, which allows for easy creation of a desired design. Furthermore, the colored decorative layer formed using inkjet ink has a first PVC layer and a second PVC layer containing a vinyl chloride resin on either side, and an adhesive layer containing a UV-curable resin is interposed between the colored decorative layer containing a UV-curable resin and the second PVC layer, making it difficult for the PVC layers to peel apart.

FIG. 1 is a plan view of a first embodiment of a flooring material for architectural interior use. FIG. 4 is a plan view of a second embodiment of an architectural interior flooring material. FIG. 2 is a cross-sectional view showing a first example of the layer structure of an architectural interior flooring material. FIG. 4 is a cross-sectional view showing a second example of the layer structure. FIG. 10 is a cross-sectional view showing a third example of the layer structure. 1 is a reference side view showing a first example of a process for forming a laminated structure when manufacturing a flooring material for architectural interiors. FIG. FIG. 10 is a reference side view showing a second example of the process for forming the laminated structure.

The present invention will now be described with reference to the accompanying drawings.
In this specification, the "surface" of an architectural interior flooring material or the "surface" of any layer that constitutes it refers to the surface away from the construction surface where the architectural interior flooring material is installed, and the "back surface" refers to the opposite surface (the side closer to the construction surface of the architectural interior flooring material). Plan view refers to viewing the flooring material from a direction perpendicular to the surface of the architectural interior flooring material.
In this specification, a numerical range expressed as "not less than a lower limit value and not more than an upper limit value" can be set to "not less than an arbitrary lower limit value and not more than an arbitrary upper limit value" by selecting an arbitrary lower limit value and an arbitrary upper limit value.
It should also be noted that the dimensions such as thickness and size in each drawing are different from the actual dimensions.

[Outline of architectural interior flooring materials]
Fig. 1 is a plan view of an architectural interior flooring material 1 according to a first embodiment, and Fig. 2 is a plan view of an architectural interior flooring material 1 according to a second embodiment. Hereinafter, the term "architectural interior flooring material" may be simply referred to as "flooring material."
Referring to Figure 1, the flooring material 1 is formed in a long strip shape in a plan view. The long strip shape refers to a generally rectangular shape in a plan view, in which the longitudinal length is sufficiently longer than the lateral length, for example, the longitudinal length is at least three times, preferably at least five times, the lateral length. Specific dimensions of the long strip include, for example, a lateral length of 500 mm to 3000 mm and a longitudinal length of 2 m to 500 m. The flooring material 1 formed in a long strip shape is usually wound into a roll for storage and transportation, and is then cut to the desired shape at the construction site for use.

Referring to Figure 2, the flooring material 1 is formed in the form of a sheet that is approximately square in plan view. However, the sheet-shaped flooring material 1 may also be formed in an approximately rectangular or hexagonal shape in plan view (not shown). Specific dimensions of the approximately square or rectangular flooring material 1 in plan view include, for example, length x width = 200 mm to 1000 mm x 200 mm to 1000 mm. Sheet-shaped flooring materials 1 such as those shown in the figure are stored and transported in a stacked state or individually rolled up.

The flooring material 1 of the present invention may be flexible or may be relatively hard without flexibility. The flexibility of the flooring material 1 is such that, for example, the back side of the flooring material 1 can be wound around a core having a diameter of 10 cm in a roll shape with the back side facing the core.
The overall thickness of the flooring material 1 is not particularly limited and is, for example, 0.5 mm to 10 mm, preferably 1 mm to 8 mm, and more preferably 1.5 mm to 5 mm.

[Layer structure of architectural interior flooring materials]
The flooring material 1 has a surface layer 2 including a colored decorative layer. The color of the colored decorative layer is displayed on the surface of the flooring material 1. The design of the flooring material 1 is determined by the color of the colored decorative layer. The surface of the surface layer 2 forms the surface of the flooring material 1. Therefore, the flooring material 1 of the present invention does not have pile yarn or fabric on its surface, and the surface of the flooring material 1 is formed of a PVC layer.
The architectural interior flooring material 1 of the present invention may be composed of only the surface layer 2, or may be composed of the surface layer 2 and a back layer laminated on the back side of the surface layer 2.
The surface layer 2 has, in this order, a first PVC layer containing a vinyl chloride resin, a colored decorative layer formed from an inkjet ink, an adhesive layer containing an ionizing radiation curable resin or a thermosetting resin, and a second PVC layer containing a vinyl chloride resin. In the surface layer 2 having the first PVC layer, colored decorative layer, adhesive layer, and second PVC layer in this order, the first PVC layer may form the surface of the surface layer 2, or the second PVC layer may form the surface of the surface layer 2. The first PVC layer and the colored decorative layer are firmly bonded directly, and the colored decorative layer and the second PVC layer are firmly bonded via an adhesive layer.

3 to 5 show first to third examples of the layer structure of the architectural interior flooring material 1. Figures 3 to 5 are cross-sectional views taken along the line III-III in Figures 1 and 2.
The flooring material 1 in Figure 3 has, from the surface side, a surface layer 2 and a back layer 3. The surface layer 2 has, from the surface side, a first PVC layer 21 containing a vinyl chloride resin, a colored decorative layer 23 formed from inkjet ink, an adhesive layer 24 containing an ionizing radiation curable resin or a thermosetting resin, and a second PVC layer 22 containing a vinyl chloride resin. In this case, the first PVC layer 21 forms the outermost surface of the flooring material 1. The back layer 3 has, from the surface side, a first resin layer 31, a second resin layer 32, and a third resin layer 33. Note that the back layer 3 may have four or more resin layers.

The flooring material 1 in Fig. 4 differs from the example of the layer configuration in Fig. 3 in that the surface layer 2 has, from the surface side, a second PVC layer 22, an adhesive layer 24, a colored decorative layer 23, and a first PVC layer 21. In this case, the second PVC layer 22 forms the outermost surface of the flooring material 1.
The PVC layer provided on the surface side of the colored decorative layer 23 may be made relatively thick to adequately protect the colored decorative layer 23. In this regard, when the second PVC layer 22 is disposed on the surface side of the colored decorative layer 23 as described above, the thickness of the first PVC layer 21, which serves as the supporting substrate for the colored decorative layer 23, can be made smaller. Therefore, when a decorative sheet in which a colored decorative layer and an adhesive layer are formed on a first PVC sheet is manufactured in advance, this decorative sheet becomes easier to store and transport, and storage and transportation of the decorative sheet in a rolled state becomes particularly easy.

The flooring material 1 in Figure 5 differs from the layer configuration examples in Figures 3 and 4 in that the back layer 3 has a first resin layer 31 and a second resin layer 32, and in that a scratch-resistant layer 25 is provided on the surface of the surface layer 2. In this case, the scratch-resistant layer 25 forms the outermost surface of the flooring material 1 and is provided to impart abrasion resistance, scratch resistance, and stain resistance to the flooring material 1. The scratch-resistant layer is formed, for example, from an ultraviolet-curable resin. The thickness of the scratch-resistant layer 25 is not particularly limited, but is, for example, from 1 μm to 150 μm, preferably from 5 μm to 100 μm, and more preferably from 10 μm to 50 μm. Note that Figure 5 shows the layer structure shown in Figure 3 as the surface layer 2 (in order from the surface side, first PVC layer 21/colored decorative layer 23/adhesive layer 24/second PVC layer 22), but it may also have the layer structure shown in Figure 4 (in order from the surface side, second PVC layer 22/adhesive layer 24/colored decorative layer 23/first PVC layer 21).

Although not specifically shown, the back surface layer 3 may be composed of only the first resin layer 31, or may have a fiber layer such as cheesecloth in the middle and/or on the back surface of the back surface layer 3.
3 to 5 may be appropriately combined or substituted. Although not particularly shown, some layers of the back surface layer 3 may be omitted, or another functional layer may be added to the back surface layer 3. For example, an adsorption portion or adhesive portion may be provided on the back surface of the back surface layer 3 (not shown). The adsorption portion or adhesive portion is a portion that removably adheres to a construction surface such as a floor surface. Examples of materials for forming the adsorption portion include very soft foamed resins, and examples of materials for forming the adhesive portion include peel-up adhesives.

[surface]
<First PVC layer>
The first PVC layer 21 is a layer that serves as a supporting base for the colored decorative layer 23. That is, the colored decorative layer 23 is formed on the first PVC layer 21 by inkjet printing on the first PVC layer 21. The colored decorative layer 23 formed on the first PVC layer 21 is firmly adhered to the first PVC layer 21.
The first PVC layer 21 contains a vinyl chloride resin, and may contain a plasticizer, a filler, and any suitable additives as needed.

Vinyl chloride resins are polymers formed by polymerizing at least vinyl chloride monomer (chloroethylene). Vinyl chloride resins include not only homopolymers (polymers formed by homopolymerizing chloroethylene), but also copolymers of chloroethylene and other monomers copolymerizable with chloroethylene, mixtures of homopolymers and copolymers, and mixtures of two or more copolymers. Note that "mixtures" refer to homopolymers and copolymers, or polymers in which copolymers are kneaded together without substantial polymerization. Examples of vinyl chloride resins include vinyl chloride polymers (homopolymers); chlorinated vinyl chloride; partially crosslinked vinyl chloride; copolymers containing vinyl chloride such as vinyl chloride-vinyl acetate copolymer, vinyl chloride-ethylene copolymer, vinyl chloride-propylene copolymer, vinyl chloride-styrene copolymer, vinyl chloride-isobutylene copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-butadiene copolymer, vinyl chloride-isoprene copolymer, and vinyl chloride-chlorinated propylene copolymer; mixtures of homopolymers and one or more copolymers; and mixtures of two or more copolymers. Preferably, a vinyl chloride polymer (homopolymer) is used. These vinyl chloride resins may be used alone or in combination of two or more.

The vinyl chloride polymer (homopolymer) can be produced by emulsion polymerization, suspension polymerization, solution polymerization, bulk polymerization, or the like, and it is preferable to use a paste vinyl chloride resin and/or a suspension vinyl chloride resin.
The vinyl chloride resin paste is a vinyl chloride resin paste obtained by, for example, emulsion polymerization, and its viscosity can be appropriately adjusted by adding a plasticizer. The vinyl chloride resin paste is a fine powder consisting of a large number of fine particle aggregates with a particle diameter of 0.1 to 10 μm (preferably 1 to 3 μm), and the surface of the fine powder is preferably coated with a surfactant. The vinyl chloride resin paste preferably has an average degree of polymerization of about 1,000 to 2,000.
The suspension vinyl chloride resin is, for example, a vinyl chloride resin obtained by suspension polymerization. The suspension vinyl chloride resin is a fine powder having a particle size of preferably 20 μm to 100 μm. The average polymerization degree of the suspension vinyl chloride resin is preferably about 700 to 1500, more preferably about 700 to 1100, and even more preferably about 700 to 1000.

The first PVC layer 21 preferably comprises a suspension vinyl chloride resin.
The first PVC layer 21 may contain other resins or may not contain other resins, provided that it contains a vinyl chloride resin as a main component resin.
In this specification, the main component resin of a certain layer means a resin that accounts for 60% by weight or more, preferably 80% by weight or more, and more preferably 90% by weight or more of the total resin components contained in the layer (when the total resin components are taken as 100% by weight).

The plasticizer is blended mainly for the purpose of improving the flexibility of the vinyl chloride resin. Examples of the plasticizer include polyester plasticizers, glycerin plasticizers, polycarboxylic acid ester plasticizers, and polyalkylene glycol plasticizers. Preferably, the plasticizer is a polycarboxylic acid plasticizer, more preferably a phthalate ester, and particularly preferably dioctyl phthalate.
The amount of the plasticizer is not particularly limited, and is, for example, 15% by weight to 50% by weight, and preferably 20% by weight to 45% by weight, with the entire first PVC layer being 100% by weight.

Fillers are added mainly for the purposes of improving processability and physical properties, and reducing product costs. Fillers are added as needed.
The filler may be opaque, transparent, or translucent. Examples of opaque fillers include calcium carbonate, titanium oxide, calcium oxide, barium carbonate, magnesium hydroxide, aluminum hydroxide, clay, talc, and mica. Examples of transparent or translucent fillers include resin beads and glass beads, with resin beads being particularly preferred, and acrylic beads being suitably used, for example.
As shown in Figure 3, when the first PVC layer 21 constitutes the surface of the flooring material 1, the filler is preferably transparent or translucent, allowing the color of the colored decorative layer 23 on the back side to be seen.

When a filler is added, the amount is not particularly limited and is, for example, 3 to 30% by weight, and preferably 10 to 25% by weight, based on 100% by weight of the entire first PVC layer 21. When forming a transparent first PVC layer 21, if the amount of filler is too large, the transparency of the first PVC layer 21 may be reduced even if the filler is transparent or translucent.
In particular, when the first PVC layer 21 is placed on the back side as shown in Figure 4, the adhesion between the first PVC layer 21 and the colored decorative layer 23 can be further improved by adding a filler such as calcium carbonate to the first PVC layer 21.
Since the colored decorative layer 23 is formed by applying inkjet ink to the first PVC layer 21, the colored decorative layer 23 adheres firmly to the first PVC layer 21 even if the first PVC layer 21 is substantially free of fillers. Of course, the colored decorative layer 23 adheres firmly to the first PVC layer 21 even if the first PVC layer 21 contains the above-mentioned fillers such as calcium carbonate. If necessary, an ink-receiving layer may be provided on the printing side of the first PVC layer 21.

As the additives, conventionally known additives can be used, and examples thereof include colorants, flame retardants, stabilizers, antioxidants, lubricants, antibacterial agents, antifungal agents, surfactants, and the like.
When an additive is added, the amount is not particularly limited, and is, for example, 0.1% by weight to 5% by weight, with the entire first PVC layer 21 being 100% by weight.
As shown in Figure 3, when the first PVC layer 21 forms the surface of the flooring material 1, the first PVC layer 21 is colorless and transparent or colored and transparent in order to reveal the color of the colored decorative layer 23 on the back side. On the other hand, as shown in Figure 4, when the first PVC layer 21 is disposed on the back side, it may be colorless and transparent, colored and transparent, or opaque.
When the first PVC layer 21 is disposed on the back surface side, it is preferable that the first PVC layer 21 be opaque, since it can form a background that conceals the back surface layer 3 and makes the color of the colored decorative layer 23 clear. When the first PVC layer 21 is opaque, the color can be selected appropriately. For example, an opaque white PVC layer is preferably used because it has excellent concealing properties for the back surface layer 3 and excellent color development properties for the colored decorative layer 23.
The first PVC layer 21 may be a foamed material, but is preferably a non-foamed material.

The thickness of the first PVC layer 21 is not particularly limited, but is, for example, 0.5 μm or more, preferably 1 μm or more, and more preferably 10 μm or more so that inkjet printing can be performed satisfactorily.
There is no particular upper limit to the thickness of the first PVC layer 21, but as shown in Figure 3, when the first PVC layer 21 forms the surface of the flooring 1, its thickness is, for example, 2 mm or less, preferably 1 mm or less. Also, as shown in Figure 4, when the first PVC layer 21 is placed on the back side, its thickness is, for example, 9 mm or less, preferably 0.5 mm or less. In particular, when the flooring 1 consists only of the surface layer 2 and the first PVC layer 21 is placed on the back side, a thicker first PVC layer 21 is used.

<Second PVC layer>
The second PVC layer 22 contains a vinyl chloride resin and may contain a plasticizer and any appropriate additives as needed. Furthermore, the second PVC layer 22 may contain fine particles.
As the vinyl chloride resin for the second PVC layer 22, the same as that explained in the section <First PVC layer> above is used.
When the second PVC layer 22 contains a paste vinyl chloride resin, it is possible to increase the degree of freedom in processing during manufacturing, such as foaming the second PVC layer 22. Furthermore, when the second PVC layer 22 contains a suspension vinyl chloride resin, it is possible to process the second PVC layer 22 with a reduced amount of plasticizer, and it is possible to obtain a second PVC layer 22 with excellent durability. The second PVC layer 22 preferably contains a suspension vinyl chloride resin because it is strongly bonded to the adhesive layer 24.

The plasticizer for the second PVC layer 22 is the same as that described above in the section <First PVC Layer>.
The amount of plasticizer is not particularly limited, but adding a relatively large amount of plasticizer can firmly bond the adhesive layer 24 and the second PVC layer 22. From this perspective, the amount of plasticizer is, for example, 5% by weight or more, preferably 8% by weight or more, and more preferably 10% by weight or more, based on 100% by weight of the entire second PVC layer. On the other hand, if the plasticizer is included in too much amount, the second PVC layer may become too soft, so the amount of plasticizer is, for example, 25% by weight or less, preferably 20% by weight or less.
As described below, the adhesive layer 24 contains an ionizing radiation-curable resin or a thermosetting resin, and therefore becomes relatively hard after curing. The second PVC layer 22 contains a vinyl chloride resin, and therefore can be made more flexible than the adhesive layer 24 by having the amount of plasticizer equal to or greater than the lower limit. This allows the second PVC layer 22 and the adhesive layer 24 to be easily and firmly integrated under heated conditions. Since vinyl chloride resin plasticizes at a relatively low temperature compared to other thermoplastic resins, heat degradation of the colored decorative layer 23 and the adhesive layer 24 during processing can be suppressed. Furthermore, the second PVC layer 22 can exhibit the strength required for flooring materials by having the amount of plasticizer equal to or less than the upper limit.

Additives for the second PVC layer 22 are those described above in the section on First PVC Layer. When additives are added, there are no particular restrictions on the amount, but for example, the amount is between 0.1% and 5% by weight, with the entire second PVC layer being 100% by weight.

Examples of the fine particles include inorganic fine particles and organic fine particles. Examples of the inorganic fine particles include calcium carbonate, titanium oxide, silica, calcium oxide, barium carbonate, magnesium hydroxide, aluminum hydroxide, clay, talc, mica, etc. Examples of the organic fine particles include fine particles made of various synthetic resins.
The fine particles are blended to firmly bond the second PVC layer 22 to the adhesive layer 24. Inorganic fine particles are preferred because they can further improve the adhesion between the two, and among these, calcium carbonate and talc are more preferred, with calcium carbonate being even more preferred.
The shape of the fine particles may be regular, such as approximately spherical or approximately needle-like, or may be irregular, with no particular shape specified. Since this can further improve the adhesiveness between the two, it is preferable that the fine particles have an irregular shape. In particular, the use of irregular calcium carbonate can enhance the adhesiveness.

The size of the fine particles is not particularly limited. To further improve the adhesiveness between the second PVC layer 22 and the adhesive layer 24, it is preferable to use fine particles having an average particle size of 0.1 μm to 50 μm, more preferably 0.1 μm to 25 μm, even more preferably 1 μm to 10 μm, and particularly preferably 1.5 μm to 7 μm. By using calcium carbonate within the above average particle size range, adhesiveness can be improved.
The average particle size is a value measured by a laser diffraction scattering method, and specifically refers to the particle size at 50% cumulative volume (D50) of the particle size distribution measured using a laser diffraction particle size distribution analyzer.
In particular, as shown in Figure 3, when the second PVC layer 22 is placed on the back side, the adhesion between the second PVC layer 22 and the adhesive layer 24 can be further improved by the second PVC layer 22 containing fine particles.

When microparticles are blended into the second PVC layer 22, the amount of the microparticles, such as calcium carbonate, is not particularly limited. Because this further improves the adhesion between the second PVC layer 22 and the adhesive layer 24, the microparticles are preferably contained in an amount of 15% by weight to 80% by weight, more preferably 25% by weight to 75% by weight, and even more preferably 40% by weight to 73% by weight, based on 100% by weight of the entire second PVC layer 22.

As shown in Figure 4, when the second PVC layer 22 forms the surface of the flooring material 1, the second PVC layer 22 is colorless and transparent or colored and transparent in order to reveal the color of the colored decorative layer 23 on the back side.
On the other hand, as shown in Figure 3, when the second PVC layer 22 is disposed on the back side, it may be colorless and transparent, colored and transparent, or opaque. When the second PVC layer 22 is disposed on the back side, it is preferable that the second PVC layer 22 be opaque, as this can conceal the back layer 3 and provide a background that makes the color of the colored decorative layer 23 stand out clearly. When the second PVC layer 22 is opaque, the color can be selected appropriately. For example, a white opaque layer is preferably used because it provides excellent concealment of the back layer 3 and color development of the colored decorative layer 23. For example, a white opaque second PVC layer 22 can be formed by blending calcium carbonate as fine particles.

The thickness of the second PVC layer 22 is not particularly limited, but in order to ensure uniform adhesion to the entire colored decorative layer 23, it is, for example, 0.5 μm or more, preferably 1 μm or more, and more preferably 10 μm or more.
There is no particular upper limit to the thickness of the second PVC layer 22, but as shown in Figure 4, when the second PVC layer 22 forms the surface of the flooring material 1, its thickness is, for example, 2 mm or less, preferably 1 mm or less. Also, as shown in Figure 3, when the second PVC layer 22 is placed on the back side, its thickness is, for example, 9 mm or less, preferably 0.5 mm or less. In particular, when the flooring material 1 consists only of the surface layer 2 and the second PVC layer 22 is placed on the back side, a thicker second PVC layer 22 is used.

<Colored cosmetic layer>
The colored decorative layer 23 is a layer that imparts a design to the flooring material 1.
The design of the colored decorative layer 23 is composed of one color or multiple colors of two or more colors. Note that any one color or two or more colors imparted to the colored decorative layer 23 may have shading.
The colored decorative layer 23 is formed from inkjet ink. In other words, the colored decorative layer 23 is made of a solidified ink layer of inkjet ink. The colored decorative layer 23 is formed on the first PVC layer 21 by inkjet printing.

Inkjet inks contain a resin and a colorant, and optionally contain any suitable additives. Inkjet inks typically contain at least three colors: cyan (C), magenta (M), and yellow (Y), and may also contain black (BK) or other colors in combination as needed.
Inkjet inks can be classified by the method of solidification, and include water-based inks, solvent-based inks, ionizing radiation-curable inks such as ultraviolet-curable inks, and heat-curable inks. As described below, since inkjet printing is performed on a PVC sheet, solvent-based inks, ionizing radiation-curable inks, and heat-curable inks are preferred, with ionizing radiation-curable inks and heat-curable inks being more preferred since they require almost no drying time and have excellent durability, and ultraviolet-curable inks being even more preferred since they can be printed using a general-purpose printer.
The inkjet ink is applied to the first PVC layer 21 in an uncured state, and then when cured, becomes the colored decorative layer 23 firmly adhered to the first PVC layer 21. However, once the inkjet ink has cured to become the colored decorative layer 23, it is known that it is difficult to achieve strong adhesion even when the inkjet ink is subsequently laminated to the second PVC layer 22 under heat and pressure. In particular, if the inkjet ink contains a pigment, the colored decorative layer 23 and the second PVC layer 22 will not adhere sufficiently even when laminated under heat and pressure, and the interlayer peel strength between them will be low.

The colored decorative layer 23 formed from the ionizing radiation curable inkjet ink such as the ultraviolet curable ink contains a colorant and an ionizing radiation curable resin, and optionally contains any suitable additives.
The colored decorative layer 23 formed from the thermosetting inkjet ink contains a colorant and a thermosetting resin, and optionally contains any appropriate additives.
The colorant imparts color to the colored decorative layer 23. The colorant may be either a dye or a pigment, or a combination of a dye and a pigment. Dyes have the advantage of being excellent in color development and capable of expressing beautiful designs. Pigments have the advantage of being excellent in light resistance and durability and capable of maintaining good design properties for a long period of time.

Examples of dyes include oil-soluble dyes, disperse dyes, acid dyes, reactive dyes, cationic dyes, and direct dyes, which contain azos, anthraquinones, indigoids, phthalocyanines, carboniums, quinoneimines, methines, xanthenes, nitros, and nitroso compounds as chromophores or chromogens.
The pigment may be either organic or inorganic, or a combination of organic and inorganic pigments may be used. Examples of organic pigments include nitroso pigments, dye lake pigments, azo lake pigments, insoluble azo pigments, monoazos, disazos, condensed azo pigments, benzimidazolones, phthalocyanines, anthraquinones, perylenes, quinacridones, dioxazines, isoindolines, azomethines, and pyrrolopyrroles. Examples of inorganic pigments include oxides, hydroxides, sulfides, ferrocyanides, chromates, carbonates, silicates, phosphates, carbons (carbon black), and metal powders.
The content of the colorant in the inkjet ink is from 0.01% by weight to 10% by weight. If the content is equal to or greater than the lower limit, sufficient color can be imparted, and if the content is equal to or less than the upper limit, good ejection properties can be obtained in inkjet printing.

The ionizing radiation curable resin contains a polymerizable monomer and/or a polymerizable oligomer (photopolymerizable prepolymer), preferably further contains a polymerization initiator, and optionally contains any appropriate additives.
The ionizing radiation curable resin may be a radical polymerization system, a cationic polymerization system, or a mixture of radical polymerization and cationic polymerization systems.
As the ionizing radiation curable resin, a conventionally known resin can be used.
The ionizing radiation curable resin may contain a polymerizable monomer and/or oligomer that can undergo a polymerization reaction upon irradiation with ionizing radiation such as ultraviolet rays or electron beams, and may contain any appropriate additives as needed.

Examples of the polymerizable monomer or oligomer include a monomer or oligomer having a polymerizable unsaturated bond group such as a (meth)acrylate group or a (meth)acryloyloxy group, or an epoxy group in the molecule.
Specific examples of the polymerizable monomer include methyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, urethane (meth)acrylate, and polyol compounds having two or more thiol groups in the molecule.

Specific examples of the polymerizable oligomer include radical polymerization type oligomers such as urethane acrylate oligomers, epoxy acrylate oligomers, and polyester acrylate oligomers, and cation polymerization type oligomers such as vinyl ether oligomers and alicyclic epoxy oligomers (resins).
Specific examples of the polymerizable monomer include acrylate monomers, vinyl ether monomers, styrene-based monomers such as α-methylstyrene, urethane (meth)acrylates, and polyol compounds having two or more thiol groups in the molecule. Examples of the acrylate monomers include pentaerythritol triacrylate, neopentyl glycol diacrylate, and phosphoric acid-containing (meth)acrylates. Examples of the phosphoric acid-containing (meth)acrylates include monomers such as acryloyloxyethyl acid phosphate and bis(2-(meth)acryloyloxyethyl) acid phosphate. Examples of the vinyl ether monomers include 2-hydroxyethyl vinyl ether (HEVE), diethylene glycol monovinyl ether (DEGV), and 4-hydroxybutyl vinyl ether (HBVE).
Examples of the polymerization initiator include photoradical polymerization initiators such as benzophenone, benzoin alkyl ether (benzoethyl ether, benzobutyl ether, etc.), benzil dimethyl ketal, and acetophenone, and photocationic polymerization initiators.
The molecular weight of the polymerizable monomer or oligomer is not particularly limited, but may be, for example, in the range of 200 to 10,000.
For example, when an ultraviolet-curable resin is used as the ionizing radiation-curable resin of the inkjet ink, the polymerizable oligomer is contained in an amount of 5% by weight to 40% by weight, the polymerizable monomer is contained in an amount of 55% by weight to 90% by weight, and the polymerization initiator is contained in an amount of 1% by weight to 10% by weight. The blending ratios of these are determined appropriately taking into consideration the ejection properties in inkjet printing before curing, the hardness after curing, and the like.
Among these, a colored decorative layer 23 containing an acrylic ultraviolet-curable resin is preferred because it allows the formation of a colored decorative layer 23 that is firmly adhered to the first PVC layer 21 .

As the thermosetting resin, a conventionally known one can be used.
Examples of thermosetting resins that can be used to form the colored decorative layer 23 include epoxy resins, phenolic resins, unsaturated imide resins, cyanate resins, isocyanate resins, benzoxazine resins, oxetane resins, amino resins, unsaturated polyester resins, allyl resins, dicyclopentadiene resins, silicone resins, triazine resins, and melamine resins. Among these, a colored decorative layer 23 containing at least one thermosetting resin selected from the above examples is preferred, as it allows the formation of a colored decorative layer 23 that is firmly adhered to the first PVC layer 21.

The thickness of the colored decorative layer 23 is not particularly limited, but is, for example, from 1 μm to 50 μm, preferably from 3 μm to 30 μm, and more preferably from 5 μm to 15 μm.

<Adhesive layer>
The adhesive layer 24 is a layer for firmly bonding the colored decorative layer 23 and the second PVC layer 22. The adhesive layer 24 formed on the colored decorative layer 23 firmly adheres to the colored decorative layer 23.
The adhesive layer 24 contains an ionizing radiation curable resin or a thermosetting resin, and optionally contains any suitable additives. That is, the adhesive layer 24 is composed of a cured resin film containing at least one of an ionizing radiation curable resin and a thermosetting resin, and optionally contains any suitable additives.
The ionizing radiation curable resin constituting the adhesive layer 24 is the same as that described above in the section <Colored decorative layer>. Examples of polymerizable monomers and/or oligomers that can undergo a polymerization reaction upon irradiation with ionizing radiation such as ultraviolet light or an electron beam include those exemplified above in the section <Colored decorative layer>. The ionizing radiation curable resin constituting the adhesive layer 24 is preferably an ultraviolet curable resin, as this allows for the formation of an adhesive layer 24 with relatively excellent adhesiveness and is versatile.
The thermosetting resins described above in the section <Colored Decorative Layer> are used as the thermosetting resins constituting the adhesive layer 24. Because they can form an adhesive layer 24 with relatively excellent adhesiveness and are versatile, the thermosetting resins constituting the adhesive layer 24 are preferably at least one selected from epoxy resins, phenolic resins, unsaturated imide resins, cyanate resins, isocyanate resins, benzoxazine resins, oxetane resins, amino resins, unsaturated polyester resins, allyl resins, dicyclopentadiene resins, silicone resins, triazine resins, and melamine resins.
The ionizing radiation curable resin or thermosetting resin that constitutes the adhesive layer 24 is bonded to the second PVC layer 22 after curing, so by selecting an ionizing radiation curable resin or thermosetting resin that has high adhesion to vinyl chloride resins, the interlayer peel strength between the adhesive layer 24 and the second PVC layer 22 can be increased.

For example, when an ultraviolet-curable resin is used as the ionizing radiation-curable resin, it is sufficient that the resin contains at least one of a polymerizable monomer and a polymerizable oligomer. To reduce the viscosity of the coating solution containing the ultraviolet-curable resin and improve its coatability when forming the adhesive layer 24, the polymerization components of the ultraviolet-curable resin are preferably polymerizable monomers alone or a mixture of polymerizable monomers and polymerizable oligomers. In the ultraviolet-curable resin containing a polymerizable monomer and a polymerizable oligomer, the polymerizable oligomer is present in an amount of 5% by weight or more and 70% by weight or less, the polymerizable monomer is present in an amount of 20% by weight or more and 94% by weight or less, and the polymerization initiator is present in an amount of 1% by weight or more and 10% by weight or less. The blending ratios of these components are appropriately determined taking into consideration factors such as the coatability before curing and the hardness after curing.
In particular, since the colored decorative layer 23 and the adhesive layer 24 are firmly bonded to each other, the adhesive layer 24 preferably contains the same type of resin as the colored decorative layer 23, and more preferably contains the same type of resin as the colored decorative layer 23. For example, both the colored decorative layer 23 and the adhesive layer 24 preferably contain an acrylic ultraviolet-curable resin.
The term "same type of resin" means that the adhesive layer 24 and the colored decorative layer 23 both contain an ionizing radiation curable resin, or that the adhesive layer 24 and the colored decorative layer 23 both contain a thermosetting resin. The term "same type of resin" means that the main repeating unit of the resin component of the adhesive layer 24 and the main repeating unit of the resin component of the colored decorative layer 23 are the same.

As shown in Figure 4, when the second PVC layer 22 forms the surface of the flooring material 1, the adhesive layer 24 is colorless and transparent or colored and transparent so that the color of the colored decorative layer 23 on the back side can be revealed.
On the other hand, as shown in Figure 3, when the first PVC layer 21 forms the surface of the flooring material 1 and the second PVC layer 22 is disposed on the back side, the adhesive layer 24 may be colorless and transparent, colored and transparent, or opaque. When the second PVC layer 22 is disposed on the back side, the adhesive layer 24 may be opaque, since it can conceal the back layer 3 and provide a background that clearly shows the color of the colored decorative layer 23. When the adhesive layer 24 is opaque, its color can be selected appropriately. For example, an opaque white layer is preferred because it provides excellent concealment of the back layer 3 and excellent color development of the colored decorative layer 23. When the second PVC layer 22 is disposed on the back side, the adhesive layer 24 may be colorless and transparent, and the second PVC layer 22 may be opaque, which can also provide a background that conceals the back layer 3 and clearly shows the color of the colored decorative layer 23.

When the adhesive layer 24 is to be colored transparent or opaque, a colorant of any color is blended into the adhesive layer 24. Examples of colorants include pigments and dyes. When forming a colored transparent or opaque adhesive layer 24, from the viewpoint of firmly bonding the adhesive layer 24 and the second PVC layer 22, the adhesive layer 24 preferably does not contain a pigment but contains a dye. In the case of a colorless transparent adhesive layer 24, the adhesive layer 24 does not contain a colorant such as a pigment or dye.
Since the pigment is harder than the resin that constitutes the adhesive layer 24, an adhesive layer containing a pigment will have a higher surface hardness, which may reduce the adhesion between the adhesive layer 24 and the second PVC layer 22.

The thickness of the adhesive layer 24 is not particularly limited, but is, for example, 0.05 μm or more, and preferably 0.1 μm or more, so that it is interposed between the colored decorative layer 23 and the second PVC layer 22 to bond them together. There is no particular upper limit to the thickness of the adhesive layer 24, but since the effectiveness remains unchanged even if the thickness is too large, from a cost-effectiveness perspective, it is, for example, 200 μm or less, preferably 50 μm or less, and more preferably 30 μm or less.

[Back surface layer]
<Resin layer>
The resin layers of the back surface layer 3, such as the first resin layer 31, the second resin layer 32, and the third resin layer 33, are layers that mainly contribute to the strength and weight of the flooring material 1.
The resin layer may be a foamed or non-foamed material. When the back surface layer 3 has multiple resin layers, at least one resin layer may be made of a foam and at least one resin layer may be made of a non-foamed material, or all of the resin layers may be made of a foam or a non-foamed material. When the back surface layer 3 has multiple resin layers, the main component resins of the resin layers may be different or the main component resins of the resin layers may be the same.
The resin component of the resin layer is not particularly limited and can be any conventionally known resin. Generally, thermoplastic resins are used, and soft thermoplastic resins are also used. Examples of the thermoplastic resin include vinyl chloride resins; polyolefin resins; urethane resins; vinyl acetate resins such as ethylene-vinyl acetate copolymers; acrylic resins such as ethylene-methacrylate resins; polyamide resins; ester resins; various elastomers such as olefin elastomers and styrene elastomers; and rubber. These resins can be used alone or in combination. Because vinyl chloride resins are inexpensive, have excellent flexibility and durability, and provide strong adhesion to the surface layer 2, it is preferable for the resin layer to contain a vinyl chloride resin as a primary resin component. Examples of vinyl chloride resins used in the resin layer include those described above in the section "Second PVC Layer."

When the resin layer of the back surface layer 3 is mainly composed of a vinyl chloride resin, it contains, for example, a vinyl chloride resin, a plasticizer, a filler, and various additives as necessary. For example, when the entire resin layer is taken as 100% by weight, the resin layer contains 20% by weight to 60% by weight of vinyl chloride resin, 5% by weight to 15% by weight of plasticizer, 30% by weight to 80% by weight of filler, and 0.1% by weight to 5% by weight of additives.
The thickness of the resin layer is not particularly limited and is, for example, 0.3 mm to 9 mm, preferably 0.4 mm to 7 mm. When the back surface layer 3 has multiple resin layers, the range of the thickness of the resin layer refers to the total thickness of the multiple resin layers.

<Fiber layer>
The fiber layer of the backing layer 3 is a layer that maintains the dimensional stability of the flooring material 1 .
Examples of the fiber layer include nonwoven fabric and woven fabric. The material of the fiber constituting the nonwoven fabric or woven fabric is not particularly limited, and examples thereof include synthetic resin fibers such as polyester and polyolefin; inorganic fibers such as glass and carbon; and natural fibers. In particular, it is preferable to use a glass sheet containing glass fiber as the fiber layer because dimensional change due to temperature is small.

[Method of manufacturing interior flooring materials]
The architectural interior flooring material 1 of the present invention can be produced by the following production method, but the architectural interior flooring material 1 of the present invention is not limited to those produced by the following production method.
A method for manufacturing an architectural interior flooring material includes the steps of preparing a decorative sheet having a first PVC sheet containing a vinyl chloride resin, a colored decorative layer formed on the first PVC sheet, and an adhesive layer formed on the colored decorative layer, preparing a second PVC sheet containing a vinyl chloride resin, and forming a laminate consisting of the first PVC sheet/colored decorative layer/adhesive layer/second PVC sheet by integrating the decorative sheet and the second PVC sheet under heated conditions.
In the preparation process, the colored decorative layer is formed by printing inkjet ink on the first PVC sheet using an inkjet printer, and the adhesive layer is formed by applying a coating liquid containing an ionizing radiation curable resin or a thermosetting resin onto the colored decorative layer and curing it.

A flooring material having a backing layer can be obtained by forming a backing layer on the laminate. For example, the flooring material shown in Figure 3 can be obtained by forming a backing layer on the second PVC sheet of the laminate on the side opposite the colored decorative layer. For example, the flooring material shown in Figure 4 can be obtained by forming a backing layer on the first PVC sheet of the laminate on the side opposite the colored decorative layer.
The back surface layer may be formed simultaneously with the step of forming the laminate, or may be formed on the second PVC sheet or the first PVC sheet before the step of forming the laminate, or may be formed on the second PVC sheet or the first PVC sheet of the laminate after the laminate is formed. When producing a flooring material having a back surface layer, it is preferable to form the back surface layer simultaneously with the step of forming the laminate, since the flooring material can be produced in a single lamination step.
In the following, an example will be described in which a back surface layer is formed in the process of forming a laminate.

<Decorative sheet preparation process>
The first PVC sheet corresponds to the first PVC layer.
As described above in the section "First PVC Layer," the first PVC sheet contains a vinyl chloride resin and may contain a plasticizer, a filler, and any appropriate additives as necessary. The first PVC sheet is obtained by mixing these vinyl chloride resins and forming them into a film using a conventionally known method. The film formation method is not particularly limited, and examples include a calendar method, a melt extrusion method, and a solution casting method.

An inkjet ink is printed on one side of a first PVC sheet using an inkjet printer.
As the inkjet ink, those described above in the section <Colored decorative layer> can be used, and preferably, an ionizing radiation curable ink or a heat curable ink is used, more preferably, an ultraviolet curable inkjet ink is used, and even more preferably, an acrylic ultraviolet curable inkjet ink is used. With an inkjet printer, any desired design can be easily produced.
A colored decorative layer can be formed on the first PVC sheet by printing inkjet ink on the first PVC sheet and then solidifying the ink. Because the inkjet ink is printed directly onto the first PVC sheet and then solidified, the formed colored decorative layer (solidified ink layer) is firmly adhered to the first PVC sheet. Note that solidification is a concept that includes curing, and in the case of ionizing radiation curable ink or heat curable ink, it is generally referred to as curing.
The method of solidifying the ink depends on the ink, for example, drying in the case of water-based or solvent-based inkjet ink, irradiating the ink with a predetermined ultraviolet ray in the case of ultraviolet-curable inkjet ink, or heating the ink to a predetermined temperature in the case of heat-curable inkjet ink.
For the ultraviolet irradiation, light rays from a conventionally known ultra-high pressure mercury lamp, high pressure mercury lamp, low pressure mercury lamp, carbon arc, xenon arc, metal halide lamp, etc. For the heating of the thermosetting type, a conventionally known heating method can be used, such as heater heating, oven heating, infrared heating, laser heating, etc.
In the manufacturing process, the colored decorative layer may be in a substantially completely solidified state or a semi-solidified state before the coating liquid described below is applied.
The semi-solidified state refers to a state in which the coating liquid has solidified to the extent that it does not interfere with coating, such as mixing with the inkjet ink, when the coating liquid described below is applied, but is not completely solidified.

A coating liquid containing an ionizing radiation curable resin or a thermosetting resin, which is a material for forming an adhesive layer, is applied to the surface of the solidified or semi-solidified colored decorative layer (the surface opposite to the first PVC sheet).
As the ionizing radiation curable resin or thermosetting resin, those described above in the section on <Adhesive Layer> can be used, preferably an ultraviolet curable resin, more preferably an acrylic ultraviolet curable resin.
The method for applying the coating liquid is not particularly limited, and various coating methods such as a roll coater, blade coater, or curtain coater, and various printing methods such as screen printing, gravure printing, or inkjet printing can be used.
An adhesive layer can be formed on a colored decorative layer by applying a coating liquid onto the colored decorative layer and then curing the coating liquid. Because the coating liquid is applied directly to the colored decorative layer and then cured, the adhesive layer formed firmly adheres to the colored decorative layer. In particular, by applying a coating liquid to a semi-solidified colored decorative layer and then curing it, the adhesive layer formed is expected to adhere more firmly to the colored decorative layer.
The method for curing the coating liquid depends on the resin, for example, a coating liquid containing an ultraviolet-curable resin is irradiated with a predetermined ultraviolet ray, and a coating liquid containing a thermosetting resin is heated to a predetermined temperature. The ultraviolet ray irradiation and heating methods described above can be used.
In this way, a decorative sheet in which the first PVC sheet, the colored decorative layer, and the adhesive layer are integrated can be obtained.

<Preparation step of second PVC sheet>
The second PVC sheet corresponds to the second PVC layer.
As described above in the section "Second PVC Layer," the second PVC sheet contains a vinyl chloride resin and may contain fine particles, a plasticizer, and any other suitable additives as needed. The second PVC sheet is obtained by mixing a vinyl chloride resin and forming the mixture into a film using a conventionally known method. The film-forming method is not particularly limited, and examples thereof include a calendar method, a melt extrusion method, and a solution casting method.

<Back surface layer preparation step>
As explained above in the section "Layer structure of architectural interior flooring materials," various layer combinations are possible for the back surface layer.
A resin layer or a fiber layer is prepared according to the desired back surface layer. For example, a resin sheet formed into a film can be used as the resin layer. In the case of a resin layer containing a vinyl chloride resin as the main component, as explained in the section "Resin Layer" above, a resin sheet can be obtained by mixing the vinyl chloride resin, a plasticizer, a filler, etc., and forming the mixture into a film.

<Lamination process>
As shown in FIG. 6 , an assembly 71 is formed by stacking the decorative sheet 4 (first PVC sheet 51, colored decorative layer 53, and adhesive layer 54), the second PVC sheet 52, and the back layer-forming material 6 in this order from the front side. The decorative sheet 4 is stacked on the second PVC sheet 52 with the adhesive layer 54 of the decorative sheet 4 facing the second PVC sheet 52. The assembly 71 is heated to bond adjacent sheets and layers together, forming a laminated structure 72. In FIG. 6 , the back layer-forming material 6 is stacked in the order of a resin sheet 61, a fiber layer 64, and a resin sheet 62 from the front side. By bonding these sheets together, a back layer 3 consisting of a resin layer 31, a fiber layer 34, and a resin layer 32 is formed. The heating temperature is equal to or higher than the melting point of the vinyl chloride resin, e.g., 140°C to 200°C. To further strengthen the interlayer adhesion, the assembly 71 is preferably compressed in the thickness direction. The pressurizing method is not particularly limited, and examples thereof include a method in which the pile 71 is passed through pressure rollers 81 and 82, as in the illustrated example, and a method in which press plates are pressed from above and below the pile 71 (not shown). The pressure of the pressurizing is not particularly limited, and is, for example, 0.5 MPa or more and 10 MPa or less, and preferably 1 MPa or more and 5 MPa or less. Heating and pressurizing may be performed simultaneously, or heating may be followed by pressurizing. When heating and pressurizing are performed simultaneously, a heated pressure roller or the like is used.

The resulting laminated structure 72 consists of, from the surface side, a first PVC layer 21, a colored decorative layer 23, an adhesive layer 24, a second PVC layer 22, and a back surface layer 3, and is used as an architectural interior flooring material. If necessary, after forming the laminated structure 72, optional processes may be performed, such as embossing the front and/or back surface of the laminated structure 72 or forming a scratch-resistant layer on the surface of the laminated structure 72, and the resulting structure may then be used as an architectural interior flooring material. The scratch-resistant layer can be formed, for example, by applying a paint containing a UV-curable resin to the surface of the laminated structure 72.

In Figure 6, the decorative sheet 4 (first PVC sheet 51, colored decorative layer 53, and adhesive layer 54), the second PVC sheet 52, and the back layer-forming material 6 are layered in this order from the front side. However, as shown in Figure 7, for example, the second PVC sheet 52, the decorative sheet 4 (adhesive layer 54, colored decorative layer 53, and first PVC sheet 51), and the back layer-forming material 6 may be layered in this order from the front side to form an assembly 73. In this case, too, the second PVC sheet 52 is layered on the decorative sheet 4 with the adhesive layer 54 of the decorative sheet 4 facing the second PVC sheet 52. Thereafter, by heating, preferably by applying heat and pressure, as in Figure 6, a laminated structure 74 can be formed consisting of, from the front side, the second PVC layer 22/adhesive layer 24/colored decorative layer 23/first PVC layer 21/back layer 3. The laminated structure 74 can be used as is as an architectural interior flooring material, or, as described above, can be subjected to optional processes such as embossing the front and/or back surface of the laminated structure 74 or forming a scratch-resistant layer on the surface of the laminated structure 74, and then used as an architectural interior flooring material.

[Use of architectural interior flooring materials]
The flooring material of the present invention is particularly suitable as a flooring material for buildings where peel strength is required, for example, as an interior flooring material for various buildings such as apartment buildings, buildings, gymnasiums, and ordinary houses.
The flooring material of the present invention is laid on a construction surface such as a floor surface directly or via an adhesive or pressure-sensitive adhesive.

In the flooring material of the present invention, the colored decorative surface layer is formed from inkjet ink, so the colored decorative surface layer can be formed by inkjet printing, easily producing a desired design. Furthermore, because the surface layer comprises a first PVC layer containing a vinyl chloride resin, a colored decorative surface layer, an adhesive surface layer, and a second PVC layer containing a vinyl chloride resin, in that order, the adhesion between the layers is excellent, and peeling is resistant at the interfaces between the first PVC layer and the colored decorative surface layer, the colored decorative surface layer and the adhesive surface layer, and the adhesive surface layer and the second PVC surface layer.
In particular, as is clear from the examples below, when a vinyl chloride resin containing a plasticizer is used and the adhesive layer does not contain a pigment, a surface layer that is resistant to interlayer peeling can be formed.

The interlayer peel strength of the flooring material of the present invention is, for example, 30 N/50 mm or more, preferably 35 N/50 mm or more, and more preferably 40 N/50 mm or more. If the interlayer peel strength is equal to or greater than the above value, the flooring material has sufficient durability and can be used stably for a long period of time after construction.
The interlayer peel strength refers to the peel strength between the first PVC layer and the second PVC layer. The interlayer peel strength refers to the strength required to peel the bonded layers, and is a measure of how strongly the layers are bonded together.
The interlayer peel strength can be measured, for example, as follows: A flooring material is cut into a size of 200 mm length x 50 mm width to prepare a sample piece, and the first PVC layer and the second PVC layer are forcibly peeled off at one end in the longitudinal direction. The force required to pull the end of the separated first PVC layer and the end of the second PVC layer so that they form an angle of 180 degrees is measured using a commercially available precision universal testing machine under standard conditions (23°C, 1 atmosphere, 50% RH), and the maximum force required to peel the end of the separated first PVC layer and the end of the second PVC layer is taken as the interlayer peel strength.

The present invention will be further described in detail below with reference to examples and comparative examples. However, the present invention is not limited to the following examples.

[Example]
<Preparation of decorative sheet>
A first PVC sheet was produced by thoroughly mixing 100 parts by weight of a vinyl chloride resin (suspension type vinyl chloride resin, manufactured by Shin-Dai-Ichi Vinyl Corporation under the trade name "ZEST-800Z", degree of polymerization: 820), 29 parts by weight of a plasticizer (dioctyl phthalate), and 3 parts by weight of a Ba-Zn stabilizer, and then molding the mixture into a film having a thickness of approximately 0.28 mm using a calendar molding machine with a roll temperature set to 150°C.
A UV-curable inkjet ink was solidly printed on one side of the first PVC sheet using an inkjet printer equipped with a UV irradiation device, and the ink was cured by UV irradiation to form a colored decorative layer having a thickness of approximately 10 μm on the first PVC sheet. The inkjet ink was an acrylic UV-curable ink containing a magenta dye.

Furthermore, a coating liquid containing an ultraviolet-curable resin was applied solidly onto the colored decorative layer using a bar coater, and the coating liquid was cured by irradiating it with ultraviolet light, forming an adhesive layer approximately 15 μm thick on the colored decorative layer. In this way, a decorative sheet consisting of a first PVC sheet/colored decorative layer/adhesive layer was produced. The coating liquid containing the ultraviolet-curable resin contained an acrylic ultraviolet-curable resin and a polymerization initiator, etc. The acrylic ultraviolet-curable resin was a mixture containing a polymerizable monomer and a polymerizable oligomer.

<Preparation of second PVC sheet>
A second PVC sheet was produced by thoroughly mixing 100 parts by weight of a vinyl chloride resin (suspension type vinyl chloride resin, manufactured by Shin-Dai-Ichi Vinyl Corporation under the trade name "ZEST-800Z", degree of polymerization: 820), 29 parts by weight of a plasticizer (dioctyl phthalate), and 3 parts by weight of a Ba-Zn stabilizer, and then molding the mixture into a film having a thickness of approximately 0.5 mm using a calendar molding machine with a roll temperature set to 150°C.

<Preparation of Backside Layer Forming Material>
100 parts by weight of vinyl chloride resin (suspension type vinyl chloride resin, manufactured by Shin-Dai-Ichi Vinyl Corporation under the trade name "ZEST800Z", degree of polymerization: 820), 36 parts by weight of plasticizer (dioctyl phthalate), 259 parts by weight of filler (calcium carbonate, a mixture of Hitachi Crushed Stone Co., Ltd. under the trade name "KP200" and Chichibu Lime Industry Co., Ltd. under the trade name "TA074B"), and 3 parts by weight of Ca-Zn stabilizer (manufactured by Katsuta Chemical Industry Co., Ltd. under the trade name "HE-1218G") were thoroughly mixed and then formed into a film of approximately 1.7 mm thickness using a calendar molding machine with a roll temperature set to 150°C, to produce one resin sheet. This one resin sheet was used as the back surface layer forming material.

<Production of architectural interior flooring materials>
The stack of decorative sheets (first PVC sheet/colored decorative layer/adhesive layer)/second PVC sheet/resin sheet was heated to 140° C. and pressed using a press to integrate the sheets. The pressure applied to the stack by the press was set to approximately 0.8 MPa.
In this way, an architectural interior flooring material was produced, which consisted of, from the surface side, a first PVC layer/a colored decorative layer/an adhesive layer/a second PVC layer/a back surface layer.

[Comparative Example]
Except for not forming an adhesive layer, an architectural interior flooring material consisting of, from the surface side, a first PVC layer/colored decorative layer/second PVC layer/back surface layer was produced in the same manner as in the example.

The flooring materials of the Examples and Comparative Examples were cut into samples measuring 200 mm x 50 mm, and a cutter blade was inserted between the first and second PVC layers at one end in the longitudinal direction to separate the end of the first PVC layer from the end of the second PVC layer. The separated ends were manually pulled to separate them, and the ease of separation was evaluated sensorily. As a result, the flooring materials of the Examples were more difficult to separate than the flooring materials of the Comparative Examples.
The reason for this difference is presumed to be as follows.
In the examples, the vinyl chloride resin of the second PVC layer, which is plastic when heated and relatively flexible at room temperature, penetrates into the surface of the adhesive layer, and the resin of the adhesive layer, which softens slightly when heated, penetrates into the surface of the second PVC layer, resulting in a mutual anchoring effect that is thought to enhance the adhesive strength between the adhesive layer and the second PVC layer. In particular, if the second PVC layer contains fine particles such as calcium carbonate, the fine particles are scattered on the surface of the second PVC layer, forming irregularities on the surface, further enhancing the anchoring effect.
On the other hand, in the comparative example, the colored decorative layer and the second PVC layer are directly bonded. The colored decorative layer is often formed using inkjet ink, which provides a smooth and hard surface to enhance expressiveness. The vinyl chloride resin of the second PVC layer has difficulty penetrating the surface of the colored decorative layer, and similarly, the surface of the colored decorative layer (high-hardness surface) also has difficulty penetrating the surface of the second PVC layer. For these reasons, the interlayer peel strength of the comparative example is thought to be insufficient.
Because the colored decorative layer is formed with consideration given to design elements such as its expressiveness, there is a limit to the improvement in interlayer peel strength when the colored decorative layer and the second PVC layer are directly bonded together, as in the comparative example. On the other hand, by interposing an adhesive layer between the colored decorative layer and the second PVC layer, which does not require consideration of the design elements required of the colored decorative layer, as in the examples, it is possible to have a colored decorative layer that satisfies the design elements, while increasing the interlayer peel strength between the first PVC layer and the second PVC layer.

DESCRIPTION OF SYMBOLS 1 Architectural interior flooring material 2 Surface layer 21 First PVC layer 22 Second PVC layer 23, 53 Colored decorative layer 24, 54 Adhesive layer 3 Back surface layer 4 Decorative sheet 51 First PVC sheet 52 Second PVC sheet

Claims (6)

The flooring material for architectural interiors has a surface layer having, in this order: a first PVC layer containing a vinyl chloride resin; a colored decorative layer formed from inkjet ink and containing an ultraviolet-curable resin ; an adhesive layer containing an ultraviolet-curable resin; and a second PVC layer containing a vinyl chloride resin. the ultraviolet-curable resin of the colored decorative layer includes an acrylic ultraviolet-curable resin,
2. The architectural interior flooring material according to claim 1 , wherein the ultraviolet-curable resin of the adhesive layer comprises an acrylic ultraviolet-curable resin . The architectural interior flooring material according to claim 1 or 2, wherein the adhesive layer does not contain a pigment. The architectural interior flooring material according to claim 1 or 2, wherein the second PVC layer contains fine particles. The architectural interior flooring material according to claim 1 or 2, wherein the interlayer peel strength between the first PVC layer and the second PVC layer is 30 N/50 mm or more. A step of preparing a decorative sheet having a first PVC sheet containing a vinyl chloride resin, a colored decorative layer formed on the first PVC sheet, and an adhesive layer formed on the colored decorative layer;
providing a second PVC sheet containing a vinyl chloride resin;
and forming a laminate consisting of the first PVC sheet/colored decorative layer/adhesive layer/second PVC sheet by integrating the decorative sheet and the second PVC sheet under a heated state,
the colored decorative layer is formed by printing an inkjet ink containing an ultraviolet-curable resin on the first PVC sheet using an inkjet printer;
The method for producing a flooring material for architectural interior use, wherein the adhesive layer is formed by applying a coating liquid containing an ultraviolet-curable resin onto the colored decorative layer and curing the coating liquid.