JP4591180B2 - Flooring - Google Patents

Description

  The present invention relates to a flooring material suitably used for indoor floor surfaces in buildings such as detached houses, condominiums, apartments, recreational facilities, office buildings, and stores.

  Currently, wooden flooring materials are the 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 wooden substrate such as a solid plate of natural wood with a thickness of about 5 to 15 mm or a laminated plywood with a thickness of about 5 to 15 mm. It is the thing which stuck, or those painted goods.

  These wood-based flooring materials using natural wood have been widely accepted by consumers since the design of the surface of the wood is the most natural, friendly and beautiful wood grain.

  However, these wooden flooring materials are easily discolored when exposed to sunlight, and are prone to swelling, cracking, warping, corrosion, peeling of the veneer, etc. when wet, especially in bathroom changing rooms and bathrooms, It has been pointed out that there are problems with use in areas such as kitchens, or that the quality, price, and supply volume of the color tone and grain shape are unstable because it is a natural material. ing.

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

  However, it is extremely difficult to recycle wood flooring materials as flooring materials, both technically and economically, and only to the extent that they are pulverized and reused as particleboard raw materials. is there. In addition, such recycling use also has excessive inventory because application development corresponding to the rapid increase in supply in recent years does not proceed, and recycling use is in a deadlock situation, most of which is final disposal by landfill or incineration The current situation is.

  Under such circumstances, there is a strong social demand for the development of a flooring material that can be reused as a raw material for the same kind of flooring material after being used as a flooring material and that is suitable for recycling. In order to meet these demands, the present applicant has already mainly used a thermoplastic resin similar to the thermoplastic resin constituting the wooden resin molded body on the surface of the wooden resin molded body containing the thermoplastic resin and the wooden filler. The floor material formed by laminating decorative sheets is proposed (see Patent Document 1).

  Since this flooring is mainly composed of thermoplastic resin, it has excellent water resistance and weather resistance, is stable in terms of physical properties and design, and can be supplied in large quantities at low cost. Workability such as hammering is equivalent to wood flooring. And after use, it also has excellent recyclability that it can be pulverized as it is and reused as a molding material for the wood resin molding.

  In addition, the applicant of the present invention has made the above-described woody resin for the purpose of improving adhesiveness with a water-based or solvent-based adhesive, heat insulation that gives a warm touch similar to natural wood, and elasticity that gives a pleasant walking feeling. A floor material using a wood resin foam molded body obtained by foaming a molded body as a base material has already been proposed (see Patent Document 2).

However, the above-mentioned flooring material is a wood resin molded body or a wood resin foam molded body mainly composed of a thermoplastic resin and a wood-based filler, and is foam-molded by a Celca process. Due to the non-uniformity of the extrusion discharge amount of the resin, the smoothness of the surface of the foamed molded product may be disturbed, which may cause appearance problems such as so-called sink marks and dents. In addition, in the extrusion molding process of a resin composition containing a thermoplastic resin and a wood-based filler, the resin composition flow rate in the die of the molding machine is caused to be non-uniform due to high non-Newtonian properties, and molding is performed. There is a possibility of deteriorating the quality of the product.
JP 2001-353815 A JP 2002-120347 A

  The present invention has been made in order to solve the above-described problems, and is a flooring based on a wood-based resin foam molded article excellent in wood texture and recyclability, particularly surface smoothness. It is intended to provide floor materials that are excellent in productivity and at the same time excellent in productivity.

The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 is a foamed resin composition containing at least a homopolypropylene resin, a maleic acid-modified homopolypropylene resin, and a wood filler, and foaming. A center layer that is a foam-molded article made of a wood-based resin composition containing an agent, and an outer wall forming material mainly composed of a homopolypropylene resin whose MFR is larger than that of the resin composition. It has a wood-based resin foam molded body that is integrated so that a non-foaming outer wall layer covering the part has a core-sheath structure, and a decorative sheet is laminated on one surface thereof It is a characteristic flooring.

According to a second aspect of the present invention, in the flooring of the first aspect, the outer wall layer contains a lubricant .

Furthermore, the invention described in claim 3 is based on a wood-based resin composition containing at least a homopolypropylene resin, a maleic acid-modified homopolypropylene resin, and a wood-based filler , and a foaming agent. And a non-foaming outer wall layer comprising an outer wall forming material mainly composed of a homopolypropylene resin having an MFR larger than the resin composition and covering an outer peripheral portion of the central layer. , A floor which is integrated by a co-extrusion extrusion (coextrusion) process to form a core-sheath structure, and a step of laminating a decorative sheet on one surface of the core-sheath structure It is a manufacturing method of material.

Furthermore, the invention according to claim 4 is the method for producing a flooring material according to claim 3 , wherein, in the step of forming the core-sheath structure, a lubricant is added to the outer wall forming material constituting the outer wall layer. Thereafter, the central layer and the outer wall layer are integrated by a co-extrusion extrusion (coextrusion) process to form a core-sheath structure .

  The present invention provides a center layer in which a wood-based resin foam molded body constituting a part thereof is a foam-molded body of a wood based resin composition containing at least a thermoplastic resin, a wood based filler, and a foaming agent; The non-foaming outer wall layer covering the outer peripheral portion of the central layer is integrated so as to have a core-sheath structure, which is mainly composed of a thermoplastic resin having the same system as the thermoplastic resin and having a low molecular weight. Therefore, for example, when it is obtained by molding by a co-extrusion extrusion (coextrusion) process, the outer wall layer has a more uniform thickness and excellent smoothness. . That is, in terms of appearance such as irregularities in the smoothness of the outer wall layer surface, sink marks and dents due to non-uniformity of foaming in the foamed molded product and non-uniformity of the extrusion discharge amount in the above extrusion process of the wood resin composition. Can be improved.

  In addition, since the outer periphery of the wood-based resin foam molded body is covered with a non-foaming outer wall layer, it is possible to increase the foaming ratio of the central layer, which is the foam layer, resulting in high foaming, It is possible to reduce the weight without reducing the surface hardness or the like.

  Furthermore, as the material for forming the outer wall of the outer wall layer, it is possible to improve productivity by using a material mainly composed of the same low molecular weight thermoplastic resin as that of the wood-based resin composition constituting the central layer. It becomes possible.

  In the central layer, the wood-based resin composition constituting the center layer contains at least a thermoplastic resin and a wood-based filler, but the wood layer is formed by adopting a co-extrusion extrusion (co-extrusion) process at the time of manufacture. In the case of producing a resin-based resin foam molded article, the non-uniformity of the molten resin flow rate in the die due to the high non-Newtonian property at the time of melting the resin composition does not occur, There is no hindrance to speedy production. That is, in the co-extrusion process, the low molecular weight thermoplastic resin, which is a constituent material of the outer wall layer, is supplied between the die lip wall surface and the molten wood resin composition, and coextrusion is performed. The so-called lubrication extrusion, in which the plastic resin becomes the lubrication layer, makes the resin flow rate uniform within the die, and the wood-based resin has no irregularities in smoothness, sink marks, or dents on the outer wall layer surface. It is possible to stably provide a foam-molded product and, moreover, a flooring material excellent in quality.

  On the other hand, in order to obtain the effect as the lubricating layer, a material mainly composed of a low molecular weight thermoplastic resin similar to the thermoplastic resin constituting the central layer is used as the outer wall layer forming material constituting the outer wall layer. Therefore, the adhesion between the center layer and the outer wall layer becomes strong, and the change in the resin temperature during extrusion becomes small due to the close molding temperature to the center layer. Further, the low molecular weight of the thermoplastic used means that the non-Newtonian property is small, the resin flow rate of the molten resin can be made uniform in the production process, and the quality of the obtained flooring material is improved.

  In addition, by adding a lubricant such as metal soap and olefin WAX to the outer wall forming material that does not contain a wood filler, it is possible to improve the lubricity with the die lip wall surface of a molding machine used when making a wood resin foam molding. It is possible to further improve the uniformity of the resin flow rate of the molten resin in the production process, and to improve the quality of the obtained flooring.

  FIG. 1 shows a cross-sectional structure of an embodiment of the flooring of the present invention. The flooring 8 includes a central layer 1 which is a foamed molded body of a sheet-like base material of a wood-based resin composition containing at least a thermoplastic resin 5, a wood-based filler 4, and a foaming agent, and the thermoplastic resin 5 A wood-based resin foam molding in which a non-foamable outer wall layer 2 covering the outer peripheral portion of the center layer 1 is integrated so as to have a core-sheath structure, mainly composed of a thermoplastic resin having the same molecular weight as that of the resin. It has a body 6 and further has a decorative sheet 7 laminated on one surface thereof.

  Examples of the thermoplastic resin 5 constituting the wood resin composition include polyolefin-based polyethylene, polypropylene, polybutene, polyisoprene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-α-olefin copolymer. An appropriate one can be selected from a polymer, a propylene-α-olefin copolymer, an ethylene-ethyl acrylate copolymer, an acid-modified product of these for the purpose of improving adhesiveness, or an ionomer. Specifically, one or more of these may be selected and used.

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

On the other hand, as the wood-based filler 4 constituting the wood-based resin composition, for example, wood is broken by a cutter mill or the like, and this is pulverized by a ball mill or impeller mill or the like (wood powder). May be used.

  The average particle diameter of the wood filler 4 is preferably about 1 to 200 μm, and more preferably 10 to 150 μm. Those having an average particle size of less than 1 μm are difficult to handle, and when the amount of the wood-based filler 4 having such a particle size is large and the dispersion into the thermoplastic resin is poor, the woody material containing the same The mechanical strength of the wood-based resin foam molded body produced from the resin-based resin composition will be reduced. Moreover, when larger than 200 micrometers, the homogeneity, flatness, and mechanical strength of a wood type resin foam molding will fall.

  Moreover, it is preferable that the compounding quantity of the wood type filler 4 shall be in the range from 10 weight part to 300 weight part with respect to 100 weight part of the thermoplastic resin 5. FIG. In order to further improve the moldability and homogeneity, the wood filler is kneaded in an amount of 20 to 200 parts by weight, more preferably 30 to 150 parts by weight with respect to 100 parts by weight of the thermoplastic resin 5. Good. 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, so the workability will be deteriorated (especially at the time of construction at the corner or when replacing one piece, It becomes difficult to bend the flooring and install it.) It becomes easy to break when bent. On the other hand, if the amount is too small, the coefficient of linear expansion increases and the dimensional stability decreases, so that a change in temperature tends to cause gaps in the butt portion of the flooring or floating due to the pushing-up.

  On the other hand, in addition to the thermoplastic resin 5 and the wood filler 4 described above, a foaming agent is added to the wood resin composition for forming the foamed molded body to be the center layer 1. In the molding process of the foamed molded product, this foams to obtain a foamed molded product. In FIG. 1, the dispersed state in the wood-based resin foam molded body of the bubbles 3 generated by foaming of the foaming agent is shown together with the dispersed state of the wood-based filler 4.

  There are various methods for foaming during molding of foamed molded products, but in general, chemical foaming that generates gas by thermal decomposition or chemical reaction, and physical that vaporizes by applying heat to a low-boiling liquid. Foaming can be used. Examples of foaming agents used for these foams include inorganic sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, ammonium nitrite, sodium borohydride, light metals, azide compounds as chemical foaming agents, and organic foams. Examples of the agent include azo series, nitroso series, and hydrazide series.

  When foaming is desired at a high foaming ratio exceeding 2 times, physical foaming is mainly used. At this time, it is preferable to mainly use carbon dioxide gas or aliphatic hydrocarbon as the blowing agent. Further, a chemical foaming agent may be used in combination in order to adjust the cell shape of the foam during physical foaming.

  The kneading of each component such as the thermoplastic resin 5, the wood filler 4, the foaming agent and other additives constituting the wood resin composition is not particularly limited, but is carried out by a Banbury mixer. Specific examples include a method of pelletizing with a pelletizer and a method of mixing and pelletizing with a twin-screw extrusion kneader. Further, since the wood filler 4 causes foaming during pelletization when the moisture content is large, it is desirable to keep the moisture content to 8% or less in advance with a dryer or hopper dryer before kneading.

  As described above, the flooring 8 of the present invention is integrated so that the center layer 1 and the outer wall layer 2 which are foam molded bodies of the woody resin composition having such a composition have a core-sheath structure. Although it has the wood type resin foaming molding 6, the outer wall layer 2 which comprises the outer peripheral part of the wood type resin foaming molding 6 is explained in full detail below.

The outer wall layer 2 is made of a material for forming an outer wall mainly composed of a thermoplastic resin having the same molecular weight as that of the thermoplastic resin of the wood-based resin composition constituting the central layer 1.

  Specific thermoplastic resins include polyethylene, polypropylene, polybutene, polyisoprene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-α-olefin copolymer, propylene-α-olefin copolymer. , Ethylene-ethyl acrylate copolymers, those obtained by acid modification for the purpose of improving adhesiveness, ionomers, mixtures thereof, copolymers, and the like.

  The outer wall forming material mainly composed of these thermoplastic resins includes a heat stabilizer, an acid neutralizer, an ultraviolet absorber, an antiblocking agent, a dehydrating agent, a light scattering agent for translucency, if necessary. A gloss adjusting agent or the like can also be added.

  Of these additives, heat stabilizers include hindered phenols, sulfur and phosphorus, acid neutralizers include stearic acid metal salts and hydrotalcite, and UV absorbers such as benzotriazole. Benzoate-based, benzophenone-based, triazine-based and the like, and examples of the light stabilizer include hindered amine-based compounds.

  In addition, a known lubricant is added to the outer wall forming material used for molding the outer wall layer 2 in order to obtain the effect of uniformizing the resin flow rate when molding the wood-based resin foam molding 6. It is desirable to do. Examples of the lubricant include olefin WAX, fatty acid, higher alcohol, fatty acid amide, metal soap such as calcium stearate and magnesium stearate, ester, and fluorine. Any combination of these lubricants may be used, but among them, a metal soap system is preferred because of its low cost and few problems of bleed-out after molding.

  Moreover, the thickness of the outer wall layer 2 should just exist in the range of 0.01-0.2 times with respect to the whole thickness of the wood type resin foaming molding 6, Preferably it is 0.05-0.15 times. When the thickness of the outer wall layer 2 is thin, it is difficult to reflect the smoothness of the surface of the foamed molded body, and it is difficult to obtain effects such as improvement in productivity by uniformizing the resin flow rate. Moreover, when the thickness of the outer wall layer 2 is thick, the merits inherent to this kind of flooring such as wood texture, machinability, light weight due to low specific gravity, and thermal stability are lost.

  In order to manufacture the wood-based resin foam molded body 6 by integrating the center layer 1 and the outer wall layer 2 described so as to have a core-sheath structure, for example, a normal profile extrusion method can be used. Of these, the Selca molding method capable of continuously and stably performing foam molding is preferable. Further, the co-extrusion process can also be carried out by a conventionally known method. However, the outer wall layer 2 is non-foamed, and the thermoplastic resin having the above-mentioned characteristics is mainly used as a constituent material thereof. It is preferable that molding is performed by a die connected to a vertical extruder because variations in discharge due to shortage hardly occur and space can be saved.

  As mentioned above, although the structure of the wood type resin foam molding 6 and its manufacturing method were described, the flooring 8 of the present invention is similar to the thermoplastic resin 5 on one surface of the wood resin foam molding 6 described above. It is obtained by laminating a decorative sheet 7 having a base sheet mainly composed of a thermoplastic resin. The constituent material of the base sheet of the decorative sheet 7 is mainly composed of a thermoplastic resin similar to the thermoplastic resin 5, so that the ground material is mixed when the used flooring is collected and recycled. Does not cause a significant change in physical properties.

Specific examples of the base sheet include polyethylene, polypropylene, polybutene, polyisoprene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-α-olefin copolymer, propylene-α-olefin. A plastic sheet made of a copolymer, an ethylene-ethyl acrylate copolymer, an acid-modified one of these for the purpose of improving adhesiveness, an ionomer, a mixture thereof, a copolymer, or the like can be used.

  Further, the flooring of the present invention has a foam layer mainly composed of a thermoplastic resin similar to the thermoplastic resin 5 constituting the wood resin foam molded body on the back surface of the wood resin foam molded body having the structure described above. (Not shown) may be laminated. If such a foam layer is laminated on the back side of the flooring, it absorbs unevenness on the bottom surface of the floor to prevent rattling, or absorbs impact sounds and walking sounds of articles on the floor surface. Effects such as preventing noise can be exhibited.

  This foamed layer is made of, for example, a chemical foaming agent or a low-boiling point which generates gas by the thermal decomposition or chemical reaction to the thermoplastic resin similar to the thermoplastic resin used in the woody resin composition for molding a woody resin foam molded article. The foamed molded body foam-molded in the form of a sheet with a resin composition containing one of the physical foaming agents that vaporize the liquid by heating is not laminated with the wood resin foam molded body decorative sheet It can be formed by bonding to the back surface.

  Hereinafter, preferred embodiments of the present invention will be described.

  First, 100 parts by weight of a homopolypropylene resin (thermoplastic resin) obtained by adding 20% by weight of a maleic acid-modified homopolypropylene resin to a homopolypropylene resin, and the wood is broken by a cutter mill, and this is pulverized by a ball mill. 100 parts by weight of a finely pulverized wood filler having an average particle diameter of 100 μm was mixed by a twin-screw extrusion kneader and pelletized to prepare a resin composition. It was 1.0 g / 10min when MFR of the produced resin composition was measured.

  Next, 3 parts by weight of triallyl isocyanurate and sodium bicarbonate-citrate foaming agent were added to 100 parts by weight of the resin composition, and the mixture was put into a single screw extruder. At the same time, an outer wall forming material in which 5 parts by weight of calcium stearate is mixed with 100 parts by weight of homopolypropylene resin (MFR = 10 g / 10 min) is put into a vertical extruder, and the molten resin is extruded from each die nozzle. Extrusion molding was performed. Thus, a non-foaming material mainly comprising a thermoplastic resin having a low molecular weight in the same system as the thermoplastic resin, covering the outer peripheral portion of the central layer, which is a foam molded body of the wood resin composition. A wood-based resin foam molded body integrated with the outer wall layer so as to have a core-sheath structure was obtained. The cross-sectional shape of this wood-based resin foam molded body was a rectangle, and the thickness and width thereof were 6 mm and 300 mm. Further, the expansion ratio of the central layer was 2.6 times, and the thickness of the non-foamed outer wall layer was 0.5 mm. The surface of this wood-based resin foam molded body was subjected to corona discharge treatment.

  On the other hand, on a colored polypropylene sheet having a thickness of 100 μm formed with random polypropylene containing a pigment of iron oxide and titanium oxide, wood printing is performed with urethane ink, and a homopolypropylene resin sheet (thickness 100 μm is obtained by extrusion lamination method). ) Was simultaneously embossed to obtain a laminated sheet. Next, a primer coat was applied to the back surface of the laminated sheet, and a top coat was applied to the front surface to prepare a decorative sheet made of polypropylene resin.

  Subsequently, the decorative sheet was continuously bonded to the surface of the wood resin foam molded body by a lapping method, and then cut at intervals of 1000 mm in the length direction, and the flooring of the present invention according to Example 1 was used. Got.

The wood-based resin foam molding is not subjected to co-extrusion molding, and the foaming ratio of the center layer is set to 2.0 times. Otherwise, the same procedure as in Example 1 is applied to Example 2 for comparison. Such a flooring was produced.
<Evaluation>
In the floor material according to Example 2, sink marks on the surface of the wood resin foam molded body, which are assumed to be caused by non-uniformity of the resin flow rate in the manufacturing process, were observed, but the floor material according to Example 1 is The surface of the woody resin foam molding was smooth and no sink marks were observed. Moreover, although machinability evaluation, linear expansion coefficient measurement, and mechanical property measurement were implemented with respect to each woody resin foam molded object, the big difference was not seen in both.

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

Explanation of symbols

1. · Central layer 2 ·· Outer wall layer 3 · Bubble 4 ·· Wood filler 5 ·· Thermoplastic resin 6 ·· Wood resin foamed foam 7 ·· Decorative sheet 8 ·· Floor material

Claims (4)

A center layer which is a foamed molded article comprising a resin composition comprising at least a homopolypropylene resin, a maleic acid-modified homopolypropylene resin and a wood filler, and a wood resin composition containing a foaming agent; and MFR Is made of a material for forming an outer wall mainly composed of a homopolypropylene resin larger than the resin composition, and the non-foaming outer wall layer covering the outer peripheral portion of the central layer is integrated so as to have a core-sheath structure. A flooring material comprising: a wood-based resin foam molded body, and a decorative sheet laminated on one surface thereof.   The flooring according to claim 1, wherein the outer wall layer contains a lubricant. A center layer that is a foamed molded article comprising a resin composition containing at least a homopolypropylene resin, a maleic acid-modified homopolypropylene resin and a wood filler, and a wood resin composition containing a foaming agent; and MFR A non-foaming outer wall layer comprising a material for forming an outer wall mainly composed of a homopolypropylene resin larger than the resin composition and covering an outer peripheral portion of the central layer, and a co-extrusion extrusion (coextrusion) process And a step of forming a core-sheath structure,
And a step of laminating a decorative sheet on one surface of the core-sheath structure. In the step of forming the core-sheath structure, after adding a lubricant to the outer wall forming material constituting the outer wall layer, the central layer and the outer wall layer are integrated by a co-extrusion extrusion (coextrusion) process. 4. The method for producing a flooring material according to claim 3, wherein the core-sheath structure is formed.

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