JP2009030390A - Floor material and manufacturing method thereof - Google Patents

Abstract

[PROBLEMS] To provide sufficient flame retardancy to a flooring material based on a wood resin foam molded article excellent in wood texture and recyclability, and to improve moldability without causing various problems due to imparting flame retardancy. Easily provide excellent flooring.
A flooring material having at least a component having a core-sheath structure of a center layer made of a woody resin foam molded body and a non-foamed outer wall layer (2) subjected to a flame retardant treatment, the center layer The wood-resin foam molded body in is formed by foam-molding a wood resin composition containing a thermoplastic resin (5) and a wood-based filler (4), and the outer wall layer (2) is the center layer. A flooring characterized by comprising a thermoplastic resin similar to the thermoplastic resin (5) in No. 1 and containing no woody resin.
[Selection] Figure 1

Description

  The present invention relates to a flooring material that can be used for indoor floors in buildings such as detached houses, condominiums, apartments, recreational facilities, office buildings, and stores, and a method for manufacturing the same.

  At present, wood flooring materials are most prevalent as floor materials for indoor floors in buildings such as detached houses. This wood-based flooring material is a natural wood veneer with a thickness of several hundreds μm to several mm on a solid wood substrate such as a natural wood plate with a thickness of about 5 to 15 mm or a laminated plywood with a thickness of about 5 to 15 mm. Or a coated product thereof.

  These wooden flooring materials using natural wood have been widely accepted by consumers since the design of the surface is the most natural, familiar and beautiful design of natural wood.

  However, it is easy to discolor when exposed to sunlight, and when it gets wet, it tends to swell, crack, warp, corrode, peel off the veneer, etc., especially in areas such as bathroom dressing rooms, washrooms, kitchens, etc. It has been pointed out that there are problems in use, and that the quality, price, and supply amount of color tone and grain shape are unstable because it is a natural material.

  Particularly in recent years, as social interest in global environmental protection issues has increased, mass consumption of natural timber that leads to environmental destruction has become a perception, and the use of recycled resources in the field of building materials such as flooring The approach to has come to be required.

  However, it is extremely difficult to recycle the wood flooring material as a flooring material, both technically and economically, and at most it is only crushed and recycled as a raw material for particleboard. This is also due to the lack of progress in application development in response to the rapid increase in supply in recent years, so there is an excess inventory, and recycling is in a deadlock situation. Most of the final disposal is done by landfill or incineration. .

  Therefore, there is a strong social demand for the development of a recyclable flooring that can be reused as a raw material for the same kind of flooring after use. In order to meet these demands, the present inventors have already made a thermoplastic resin similar to the thermoplastic resin contained in the wooden resin molded article on the surface of the wooden resin molded article containing the thermoplastic resin and the wooden filler. A flooring made by laminating decorative sheets mainly composed of resin has been proposed (Patent Document 1).

  Since this flooring is mainly composed of thermoplastic resin, it has excellent water resistance and weather resistance, and it can supply a large quantity of products with stable quality in terms of physical properties and design, such as cutting and nailing. The processability is equivalent to that of the wood-based flooring material, and it has excellent recyclability such that it can be pulverized as it is after use and reused as a molding material for the wood resin molding.

  In addition, the present inventors have further said wood resin molding for the purpose of improving adhesiveness by water-based or solvent-based adhesives, heat insulating property giving warm touch similar to natural wood, elasticity giving a pleasant walking feeling, etc. A floor material using a wood resin foam molded body obtained by foaming the body as a base material has also been proposed (Patent Document 2).

  Regarding floor materials using the above-described wood resin foam molded article, flame resistance of the molded article is required as a further required performance. When an olefin resin is used for the flooring, it is advantageous to the vinyl chloride resin from the viewpoint of the gas generated at the time of fire, but the material itself is inferior to the vinyl chloride resin in terms of flame retardancy of the base material itself.

As a flame retardant for thermoplastic resins, a technique by adding a flame retardant is common, but in order to obtain sufficient flame retardant, the amount of flame retardant added needs to be very large and can be obtained. This causes problems such as a decrease in mechanical properties and a decrease in moldability of the molded body.
JP 2001-353815 A JP 2002-120347 A

  The present invention has been made to solve the above-described problems in the prior art, and is sufficiently difficult for a flooring material based on a wood resin foam molded article excellent in wood texture and recyclability. The present invention intends to easily provide a flooring material having excellent moldability without imparting various problems due to imparting flame retardancy and flame retardancy.

Invention of Claim 1 is a flooring which has at least the component which has a core-sheath structure of the center layer which consists of a wood resin foaming molding, and the non-foaming outer wall layer by which the flame-retardant process was carried out, Comprising: The wood resin foam molded body in the center layer is formed by foam molding a wood resin composition containing a thermoplastic resin and a wood filler, and the outer wall layer is the same as the thermoplastic resin in the center layer. The flooring material is characterized by using a thermoplastic resin and containing no woody resin.
The invention according to claim 2 is the flooring according to claim 1, wherein the flame retardant treatment in the outer wall layer is a method in which a hydrated metal compound is added to the outer wall layer as a flame retardant. is there.
The invention according to claim 3 is characterized in that the thickness of the outer wall layer is 0.01 to 0.2 times the thickness of the entire component. Flooring.
The invention according to claim 4 is further characterized in that a flame-retardant decorative sheet mainly composed of a thermoplastic resin similar to the thermoplastic resin in the central layer wood is further laminated on the outer wall layer. The flooring material according to any one of the above.
The invention according to claim 5 has at least a component having a core-sheath structure of a center layer made of a wood resin foam molded body and a non-foamed outer wall layer subjected to flame retardancy treatment. A floor layer manufacturing method according to claim 1, wherein a center layer formed by foaming a wood resin composition containing a thermoplastic resin and a wood based filler, and a thermoplastic resin similar to the thermoplastic resin in the center layer. It is the said manufacturing method which has the process of shape | molding the component which has a core-sheath structure by carrying out co-extrusion extrusion (coextrusion) with the outer wall layer which does not contain wood resin while using resin.

  According to the first aspect of the present invention, sufficient flame retardancy is imparted to a flooring material based on a wood resin foam molded article excellent in wood texture and recyclability, and various conventional ones by imparting flame retardancy. A flooring excellent in formability can be easily provided without causing problems. When molding a wood resin foam molding with a thermoplastic resin simply added with a flame retardant, the mechanical properties of the molded body will be reduced and the weight will be increased. Decrease is a problem. On the other hand, in the flame retardancy imparting technique using the component having the core-sheath structure of the present invention, a non-foamed layer of a thermoplastic resin to which a flame retardant serving as an outer wall layer is added and a foamed layer serving as a central layer are separately supplied. By this, it is possible to mold without causing the foaming inhibition, etc., and by making the outer wall layer non-foaming, it is possible to increase the surface hardness which is a necessary physical property as a flooring material, By increasing the foaming ratio of the central layer, it is possible to achieve a cost reduction associated with the weight reduction of the entire flooring material, and it is possible to maintain an appropriate cushioning characteristic that is a feature of the present invention. In addition, since the thermoplastic resin used for the outer wall layer is the same as the thermoplastic resin of the foam layer, the adhesion between the center layer and the outer wall layer becomes stronger, and the recyclability is improved.

  As the flame retardant mechanism, flame retardant (endothermic and inert substance release) and solid layer flame retardant (carbonized layer formation) are considered, but in any case, the surface layer of the molded body is sufficient. If flame retardancy can be achieved, flame retardancy as a molded article can be obtained. From such a viewpoint, although the flame retardant of the component by the said core-sheath structure was discovered, in addition to flame retardance provision in this invention, it expresses combining the high foaming of a flooring, an improvement in physical properties, etc. It is a feature that can be.

  According to the invention described in claim 2, since the hydrated metal compound is used as the flame retardant, flame retardancy can be imparted without greatly increasing the material cost of the flooring, and the hydrated metal The surface hardness of the flooring can be effectively increased by adding the compound.

  According to the invention described in claim 3, it is possible to provide a flooring material that has an excellent balance between flame retardancy and mechanical properties and at the same time has excellent productivity. When the thickness of the outer wall layer is thin, flame retardancy, which is a feature of the present invention, is difficult to obtain, and when it is thick, there are problems such as a decrease in productivity, a decrease in mechanical properties, and an increase in the weight of the substrate.

  According to invention of Claim 4, the flooring which was excellent in the designability and provided the flame retardance can be provided. By using a flame-retardant decorative sheet as the decorative sheet to be laminated, it becomes possible to obtain more excellent flame-retardant performance as a flooring material.

  According to the invention described in claim 5, sufficient flame retardancy is imparted to a flooring material based on a wood resin foam molded article excellent in wood texture and recyclability, and various conventional flame retardant imparts are provided. A flooring excellent in formability can be easily provided without causing problems.

Hereinafter, the present invention will be described in more detail.
The cross-sectional structure of an embodiment of the flooring of the present invention is shown in FIG. A thermoplastic resin (5) and a wooden filler (4) are molded into a wooden resin foam molding layer formed by foaming (with the presence of bubbles (3) therein), and the thermoplastic resin ( The thermoplastic resin (5) is formed into a molded product having the core-sheath structure in which a thermoplastic resin flame-retardant treated by adding a flame retardant is molded as a non-foamed outer wall layer (2). A flame retardant decorative sheet (1) made of the same thermoplastic resin is laminated.

  Examples of the thermoplastic resin (5) in the present invention include polyolefins such as polyethylene, polypropylene, polybutene, polyisoprene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-α-olefin copolymer, propylene. -Α-olefin copolymer, ethylene-ethyl acrylate copolymer, those obtained by acid modification for the purpose of improving adhesiveness, ionomer, etc. can be appropriately selected. Absent.

  Among them, polypropylene resins such as homopolypropylene, random polypropylene, block polypropylene, and propylene-α-olefin copolymer are most suitable in terms of rigidity, surface hardness, dimensional stability and the like required for flooring materials.

  In the present invention, the material of the wood filler (4) used in the wood resin foam molded article can be selected without any particular restriction, but generally the wood is broken by a cutter mill or the like. These are pulverized by a ball mill, an impeller mill, or the like to obtain a fine powder (wood powder).

  1-200 micrometers is preferable and, as for the average particle diameter of a wood type filler (4), 10-150 micrometers is more preferable. Those with an average particle size of less than 1 μm are difficult to handle, and especially when the amount of the wood filler is large, the mechanical strength of the wood resin foam molded article produced when the dispersion into the resin is poor Occurs. On the other hand, if it is larger than 200 μm, the homogeneity, flatness and mechanical strength of the molded product are lowered.

  The amount of the wood filler (4) can be appropriately selected from 10 parts by weight to 300 parts by weight with respect to 100 parts by weight of the thermoplastic resin (5). In order to increase the amount, the wood filler (4) is desirably 20 to 200 parts by weight, more preferably 30 to 150 parts by weight, based on 100 parts by weight of the thermoplastic resin (5). If the amount of the wood filler (4) is too large, the flexural modulus of the flooring will increase and the flexibility will be lost. At the time of replacement, it becomes difficult to bend the flooring and install it), and when it is bent, it becomes easy to break. On the other hand, if the amount is too small, the coefficient of linear expansion becomes large and the dimensional stability is lowered. Therefore, due to temperature changes, gaps between the flooring materials or floating due to the pushing-up of the flooring materials may occur. Cause.

  In the present invention, in addition to the thermoplastic resin (5) and the wood filler (4), a foaming agent is added to the wood resin composition for molding the wood resin foam molded article of the center layer. Foamed during the molding process.

  Any known technique can be used for the foaming technique. In general, chemical foaming can be classified into chemical foaming, which generates gas by thermal decomposition or chemical reaction, and physical foaming, which heats a low-boiling point liquid to vaporize, and chemical foaming agents include inorganic sodium bicarbonate and carbonic acid. Ammonium, ammonium bicarbonate, ammonium nitrite, sodium borohydride, light metals, azide compounds, etc., and organic foaming agents such as azo, nitroso, hydrazide, etc. can be used in any combination.

  In particular, physical foaming is mainly used for foaming at a high foaming ratio exceeding 2 times, and carbon dioxide gas and aliphatic hydrocarbons are mainly used as foaming agents. In addition, a chemical foaming agent is often used in combination with physical foaming to adjust the cell shape of the foam.

  In the present invention, an ordinary profile extrusion method can be used for forming the wood resin foam molded article. Among these, the SELKA molding method is preferable so that continuous and stable foam molding is possible. The co-extrusion process is also carried out by a conventionally known method. However, since the outer wall layer is non-foamed, it is difficult to cause variations in discharge due to insufficient melting in the extrusion process, and vertical extrusion from the viewpoint of space saving. It is preferable to design a die that connects the machines.

  Next, the outer wall layer (2) in the present invention uses a thermoplastic resin similar to the thermoplastic resin in the center layer, and does not contain a woody resin. In the present invention, it is important that the thermoplastic resin of the same type can be recycled without significant change in physical properties even when mixed with each other. Specifically, the thermoplastic resin in the central layer is, for example, a polyolefin. Polyethylene resin, polypropylene, polybutene, polyisoprene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-α olefin copolymer, propylene-α olefin copolymer, ethylene-ethyl acrylate From copolymers, acid-modified products thereof (grafted with unsaturated carboxylic acid or anhydride for the purpose of improving adhesion), ionomers (metal hydrates of olefin-unsaturated carboxylic acid copolymers), etc. Appropriate selection is possible.

  In the present invention, as a flame retardant added to the thermoplastic resin of the outer wall layer (2), a general flame retardant added to a polypropylene material, for example, a brominated flame retardant, a phosphorus flame retardant, a hydrated metal compound, etc. However, it is preferable to use a hydrated metal compound from the viewpoints of environmental adaptability, cost, moldability, and improvement of surface height of the outer wall layer. Specifically, aluminum hydroxide, magnesium hydroxide, or the like is used, but considering the molding temperature of polypropylene, it is more preferable to use magnesium hydroxide in view of stability during molding.

  The addition amount of the hydrated metal compound is more preferably 50 parts by weight or more and 300 parts by weight or less, preferably 80 parts by weight or more and 250 parts by weight with respect to 100 parts by weight of the thermoplastic resin used for the outer wall layer. When the addition amount of the hydrated metal compound is small, the flame retardancy that is a feature of the present invention cannot be imparted, and when the addition amount is large, the amount of resin is small and molding becomes difficult. Also, the molded product is very brittle and has poor physical properties.

  In the present invention, the thermoplastic resin used for molding the outer wall layer (2) includes a heat stabilizer, an acid neutralizer, an ultraviolet absorber, an antiblocking agent, a dehydrating agent, and a semitransparent material as necessary. Light scattering agents, gloss adjusting agents, and the like can also be added.

  Among these additives, hindered phenols, sulfurs, phosphoruss, etc. as heat stabilizers, stearic acid metal salts, hydrotalcite, etc. as acid neutralizers, benzotriazoles, benzoates as ultraviolet absorbers, etc. Benzophenone, triazine, etc., and light stabilizers include hindered amines.

  Moreover, in order to obtain the component which has the core-sheath structure by this invention, it is desirable to add a well-known lubricant to the thermoplastic resin of an outer wall layer. Stable production is possible by adding a lubricant to the thermoplastic resin of the outer wall layer to increase the external lubricity. Lubricants include olefin waxes, fatty acids, higher alcohols, fatty acid amides, metal soaps such as calcium stearate and magnesium stearate, esters, and fluorines. Use these lubricants in any combination. I can do it. Among these, it is desirable to use a metal soap system because it is low in cost and has few problems of bleeding out after molding.

  In the present invention, the thickness of the outer wall layer is 0.01 to 0.2 times, preferably 0.05 to 0.15 times the thickness of the entire component. When the thickness of the outer wall layer is thin, the flame retardancy characteristic of the present invention cannot be obtained, and when it is thick, there are problems such as a decrease in productivity, a decrease in mechanical properties, and an increase in the weight of the substrate.

  In the present invention, thermoplastic resin (5) constituting the wood resin composition, wood filler (4), kneading of the foaming agent and other additives, or thermoplastic resin constituting the outer wall layer (2), The method of kneading the flame retardant and other additives is not particularly limited, but a method of kneading with a Banbury mixer and pelletizing with a pelletizer or a method of mixing and pelletizing with a twin screw extrusion kneader are common. . Further, the wood filler (4) has a high moisture content, which causes foaming during pelletization. Therefore, it is desirable to suppress the moisture content to 8% or less with a dryer or hopper dryer before kneading.

  In the flooring of the present invention, it is preferable to laminate a flame retardant decorative sheet (1) mainly composed of a thermoplastic resin similar to the thermoplastic resin (5) on the surface of the wood resin foam molded article. By using a similar thermoplastic resin, it is possible to recycle without significant change in physical properties even when mixed during the recycling process.

  When the thermoplastic resin (5) is a polyolefin, specifically, for example, polyethylene, polypropylene, polybutene, polyisoprene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, An ethylene-α-olefin copolymer, a propylene-α-olefin copolymer, an ethylene-ethyl acrylate copolymer, an acid-modified one of these for the purpose of improving adhesion, an ionomer, etc., or a mixture thereof, It can be appropriately selected from various polyolefin resins such as polymers, and can be used as a thermoplastic resin for the flame-retardant decorative sheet (1).

  The important point about the flame-retardant decorative sheet (1) to be laminated is that it is a decorative sheet imparted with flame retardancy, and in the present invention, there is no restriction on the configuration of the decorative sheet itself.

  This flame-retardant decorative sheet (1) is, for example, a single-layer decorative sheet printed on a colored sheet, a transparent sheet on a sheet printed on a colored sheet by a dry laminating method, an extrusion laminating method, a thermal laminating method, or the like. It can be appropriately selected depending on the application from a laminated decorative sheet laminated, a back-printed decorative sheet printed on the back surface of a transparent sheet, and the like.

  There are no particular restrictions on imparting flame retardancy to the flame retardant decorative sheet (1), such as a technique for printing on a commercially available flame retardant sheet or a technique for applying an inorganic coating agent to the outermost surface. Can be used. However, it is preferable to use a sheet made of the same method as the decorative sheet from the viewpoint of imparting flame retardancy to the floor base material to be bonded, using a method of adding a hydrated metal compound.

  Ink used for printing patterns such as woodgrain pattern, picture pattern, coloring, etc. of flame retardant decorative sheet (1) Nitrified cotton, cellulose, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, polyurethane, acrylic, What is necessary is just to select suitably from individual or each modified material, such as a polyester type. These may be any of aqueous, solvent-based and emulsion types, and can be arbitrarily selected from a one-component type or a two-component type using a curing agent. Further, it is possible to cure the ink by irradiation with ultraviolet rays or electron beams.

  Among them, the most general method is a method of curing urethane-based ink with isocyanate. In addition to these binders, colorants such as pigments and dyes, extender pigments, solvents, and various additives contained in ordinary inks are added. Particularly frequently used pigments include condensed azo, insoluble azo, quinacridone, isoindolinone, anthraquinone, imidazolone, cobalt, phthalocyanine, carbon, titanium oxide, iron oxide, mica and other pearl pigments.

  Moreover, in any flame-retardant decorative sheet (1), a primer coat for bonding to a core-sheath wood-based foam molded body, a top coat for surface protection and gloss adjustment, an embossing method and a gloss mat It does not matter if the conduit expression by law is given. Moreover, the additive used for the thermoplastic resin layer in the flame-retardant decorative sheet (1) can be used as appropriate in the same manner as in the above constituent elements.

  The thickness of the flame-retardant decorative sheet (1) is not particularly limited, but is usually in the range of about 0.05 to 0.3 mm. The lamination method of the flame-retardant decorative sheet (1) and the constituent elements is not particularly limited. For example, a dry lamination method or a wet lamination method with an adhesive, a thermal lamination method with or without an adhesive, an ultrasonic fusion Conventionally known methods such as a deposition method, a high-frequency fusion method, and a simultaneous molding lamination method in which a decorative sheet (1) is introduced into a cooling sizing mold and bonded together with foam extrusion molding of components can be arbitrarily used. .

  Furthermore, in the flooring of the present invention, a foam layer (not shown) mainly composed of a thermoplastic resin similar to the thermoplastic resin (5) may be laminated on the back surface of the component. For example, if a foam layer is laminated on the back side of the flooring, it absorbs the unevenness of the floor surface and prevents rattling, or absorbs the impact sound and walking sound of articles on the floor. There are effects such as preventing.

As a method for laminating the foam layer, a known method can be used. For example, a thermoplastic resin similar to the thermoplastic resin (5), a chemical foaming agent that generates gas by the thermal decomposition or a chemical reaction, or a low boiling point liquid. It can be formed by sticking a foam molded body foam-molded into a sheet shape with any foaming agent of a physical foaming agent that is vaporized by applying heat to the back surface on which the flame-retardant decorative sheet (1) is not laminated.
(Example)

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further, this invention is not restrict | limited to the following example.
Example 1

  As a thermoplastic resin, a homopolypropylene resin obtained by adding 20% by weight of a maleic acid-modified homopolypropylene resin to a homopolypropylene resin was used. The powder was pulverized by a ball mill into a fine powder and the average particle size was 100 μm, and 100 parts by weight was mixed with a twin-screw extrusion kneader and pelletized to prepare a woody resin composition. 3 parts by weight of triallyl isocyanurate and baking soda-citric acid foaming agent are added to 100 parts by weight of the wood resin composition, and the foamed layer is extruded by a single screw extruder. At the same time, an outer wall layer is formed in the die nozzle. The flame-retardant thermoplastic resin formed by mixing 100 parts by weight of magnesium hydroxide with 100 parts by weight of homopolypropylene resin and 2 parts by weight of calcium stearate by a twin-screw extrusion kneader and extruding from a vertical extruder is formed. Co-extrusion molding was performed. As a result, the foam layer has a foaming ratio of 2.6 times, the entire molded body has a thickness of 6 mm, the non-foamed outer wall layer has a thickness of 0.5 mm and a width of 300 mm, and is further subjected to corona discharge treatment on the surface. Thus, a component having a core-sheath structure was produced.

On the other hand, a flame-retardant colored polypropylene sheet with a thickness of 100 μm formed by blending random polypropylene with pigments such as iron oxide and titanium oxide and magnesium hydroxide is printed with urethane-based ink and applied to the extrusion laminating method. Then, a homopolypropylene resin was simultaneously embossed with a thickness of 100 μm, a primer coat was applied to the back surface, and a top coat was applied to the front surface to prepare a decorative sheet of a flame-retardant polypropylene resin. Thereafter, the decorative sheet is continuously produced by laminating the decorative sheet on the surface of the component having the core-sheath structure by a lapping method, and then the flooring is cut to 1000 mm in the length direction to obtain the flooring of the present invention. Produced.
(Comparative Example 1)

As a thermoplastic resin, a homopolypropylene resin obtained by adding 20% by weight of maleic acid-modified homopolypropylene resin to a homopolypropylene resin was used, and 100 parts by weight of this and wood as a wooden filler were broken by a cutter mill. A wood resin composition having a mean particle size of 100 μm pulverized by a ball mill, mixed with 50 parts by weight of this and 50 parts by weight of magnesium hydroxide by a twin-screw extrusion kneader, and pelletized. Was made. The flooring was produced in the same manner as in Example 1 except that the co-extrusion molding was not performed and the foaming ratio was 1.8 times.
(Comparative Example 2)

  As a thermoplastic resin, a homopolypropylene resin obtained by adding 20% by weight of a maleic acid-modified homopolypropylene resin to a homopolypropylene resin was used, and 100 parts by weight of this material and wood as a wooden filler were broken by a cutter mill. A wood resin composition having an average particle diameter of 100 μm, pulverized by a ball mill, mixed with 50 parts by weight and 100 parts by weight of magnesium hydroxide by a twin-screw extrusion kneader and pelletized. Was made. Foam molding was attempted without performing co-extrusion molding, but the molding substrate was brittle and the substrate molding was impossible.

<Performance comparison>
For Example 1 and Comparative Example 1, flame retardancy evaluation and surface hardness test (DD2 rubber hardness meter) were performed. As a method for evaluating the flame retardancy, the 45 ° Meckel burner method of JIS L1091 was used. The evaluation results are shown in Table 1.
The flooring material according to Example 1 satisfies the flameproof standard for plywood in the Fire Service Law. Further, it was confirmed that the flame retardancy and the surface hardness were excellent as compared with Comparative Example 1.

  The flooring of the present invention is excellent in wood texture and recyclability, has sufficient flame retardancy, is excellent in moldability, and is used indoors in buildings such as detached houses, condominiums, apartments, recreational facilities, office buildings, and stores. Useful for flooring.

It is explanatory drawing which shows the structure of the cross section of one Example of the flooring of this invention.

Explanation of symbols

(1) ... Flame retardant decorative sheet (2) ... Outer wall layer (3) ... Air bubbles (4) ... Wood based filler (5) ... Thermoplastic resin

Claims (5)

A flooring material having at least a component having a core-sheath structure of a center layer composed of a wood resin foam molded body and a non-foamed outer wall layer subjected to flame retarding,
The wood resin foam molded body in the center layer is formed by foam molding a wood resin composition containing a thermoplastic resin and a wood filler, and the outer wall layer is the same as the thermoplastic resin in the center layer. A flooring material characterized by using a thermoplastic resin and containing no woody resin.   The flooring according to claim 1, wherein the flame retardant treatment in the outer wall layer is to add a hydrated metal compound to the outer wall layer as a flame retardant.   The flooring according to claim 1 or 2, wherein the thickness of the outer wall layer is 0.01 to 0.2 times the thickness of the entire component.   The flooring according to any one of claims 1 to 3, wherein a flame-retardant decorative sheet mainly composed of a thermoplastic resin similar to the thermoplastic resin in the central layer wood is further laminated on the outer wall layer. The flooring material according to any one of claims 1 to 4, which has at least a component having a core-sheath structure of a center layer made of a wood resin foam molded body and a non-foamed outer wall layer subjected to flame retardancy. A method,
A center layer formed by foam molding a wood resin composition containing a thermoplastic resin and a wood filler, and an outer wall layer using a thermoplastic resin similar to the thermoplastic resin in the center layer and containing no wood resin And the above-mentioned production method, comprising the step of forming a component having a core-sheath structure by co-extrusion extrusion (coextrusion).

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