JP2012001610A - Ground sheet and manufacturing method of decorative panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a decorative panel having outstanding appearance in which the surface is flat and smooth, and in which woody material is not used for wood resource conservation, and a substrate made from non-wood plant fiber is used.SOLUTION: The decorative panel is characterized as follows. A substrate 2 which comprises binding non-wood plant fiber by a phenolic resin is used, and a ground sheet 4 in which a resin of 100:0 to 70:30 mass ratio of a pseudothermoplastic resin to a thermoplastic resin having at most 40°C of a minimum film forming temperature (MFT) is impregnated into a fiber sheet is intervened between the substrate and a decorative sheet 3 in order to eliminate the surface unevenness nature of the substrate.

Description

  The present invention relates to a decorative panel mainly used as a building material.

2. Description of the Related Art Conventionally, as a decorative panel, a structure in which a resin-impregnated paper is bonded as a base sheet to a substrate surface and a decorative sheet is bonded thereon is provided.
Plywood, medium density fiber board, hard board, particle board, and other wooden boards are mainly used as the decorative panel substrate. However, these wooden boards have innumerable irregularities on the surface, so the surface directly When the decorative sheet is bonded to the wooden board, there is a problem that the decorative sheet floats (floats) from the wooden board. As a result, innumerable irregularities on the surface of the wooden board appear on the surface of the decorative sheet. Worsen.

Therefore, for the purpose of preventing the above-mentioned decorative panel from floating and preventing the countless irregularities of the surface of the wooden board from appearing on the surface of the decorative panel, a base sheet is adhered on the wooden board, A structure is employed in which the decorative sheet is adhered from above the innumerable irregularities on the surface of the wooden board.
As the base sheet, conventionally, fiber materials such as paper, nonwoven fabric, woven fabric, thermosetting resins such as melamine resin, phenol resin, diallyl phthalate resin, epoxy resin, unsaturated polyester resin, styrene-butadiene rubber, A resin-impregnated sheet impregnated with a thermoplastic resin such as acrylonitrile-butadiene-styrene rubber or vinyl acetate is used.

JP 2006-142638 A JP 2008-88741 A

Recently, as a substrate for the decorative panel, from the viewpoint of wood resource protection, kenaf fibers that grow in a short period of time are used instead of substrates made of wood such as plywood, medium density fiberboard, hardboard, and particleboard. In addition, the use of non-woody plant fiber substrates in which non-woody plant fibers such as hemp fiber, palm fiber, bamboo fiber, etc. are bound with a resin has been studied.
As the resin used as the binder of the non-woody plant fiber substrate, a phenolic resin is generally selected from the viewpoints of availability, strength, water resistance and the like.
Of course, since the non-wood fiber substrate has innumerable irregularities on the surface, the base sheet is necessary to conceal it. As the base sheet, as described above, a resin-impregnated sheet obtained by impregnating paper, nonwoven fabric, woven fabric or the like with a resin, particularly a diallyl phthalate resin-impregnated sheet is used.

However, the curing temperature of the phenolic resin that is the binder of the non-woody plant fiber substrate is about 180 ° C, and the curing temperature of the diallyl phthalate resin is about 120 ° C to 130 ° C. When the base sheet impregnated with uncured diallyl phthalate resin (prepolymer) is overlaid on the surface of the non-woody plant fiberboard raw material containing the condensate), the temperature of the above-mentioned hot pressing is set to phenolic. It is necessary to set to about 180 ° C., which is the curing temperature of the resin.
At such a high temperature, the diallyl phthalate resin of the base sheet is cured and adheres to the mold. To prevent this, it is necessary to apply a release agent to the mold surface or to use a release sheet. Therefore, it takes time to manufacture and the material cost becomes high.

Therefore, usually, the above-mentioned non-woody plant fiber substrate is first hot-pressed at about 180 ° C., and then a diallyl phthalate resin-impregnated base sheet is polymerized on the surface and heated and pressed again at a temperature of about 120 ° C. to 130 ° C. A method of adhering the base sheet to the surface of the non-woody plant fiber substrate is employed.
However, this method involves two steps, which is a major obstacle for mass production of decorative panels.
For example, if the base sheet is impregnated with the same resin as the phenolic resin used for the non-woody plant fiber substrate, the curing temperature of the non-woody plant fiber substrate and the base sheet can be matched, and the two steps as described above Although the above step is not necessary, the base sheet impregnated with the phenolic resin is usually pre-cured after impregnation and the phenolic resin is stored in the B state, but it is difficult to store for a long period of time. . In addition, the base sheet impregnated with the B-state phenolic resin softens the B-state phenolic resin and adheres to the mold at the time of hot-pressure molding, so that a release agent and a release sheet are also required.
If the phenolic resin in the base sheet is further cured to the C state, the phenolic resin will not be cured any longer, so long-term storage will be improved, and the phenolic resin will become a mold during hot pressing. Although it does not adhere, the base sheet impregnated with the phenolic resin in the C state loses flexibility and the moldability also deteriorates, and a decorative panel using such a base sheet can only be formed into a flat plate shape. Furthermore, the base sheet impregnated with the phenolic resin in the C state becomes hard and cannot be stored in a roll.

As means for solving the above-mentioned conventional problems, the present invention provides a pseudo-thermoplastic resin on a fiber sheet made of natural fibers, a thermoplastic film having a minimum film forming temperature (MFT) of 40 ° C. or less, and The base sheet impregnated with a resin having a mass ratio of 100: 0 to 70:30 is provided.
Furthermore, in the present invention, after the base sheet according to claim 1 is polymerized on the surface of the substrate raw material in which a phenol-based resin is mixed with a fiber containing at least 80% by mass of non-woody plant fiber as a binder, a predetermined shape is obtained. By simultaneously hot-molding the phenolic resin in the substrate original fabric and the pseudo thermoplastic resin in the base sheet, and simultaneously bonding the base material and the base sheet, The surface roughness according to the standard of JIS B 0601 (1994) is smoothened by polishing the surface of the base sheet to an arithmetic average roughness (Ra) of 5.0 μm or less and a maximum height (Ry) of 30.0 μm or less. Then, the present invention further provides a method for producing a decorative panel in which a decorative sheet is adhered on the base sheet.

[Action]
In the present invention, a fiber sheet is impregnated with 100: 0 to 70:30 mass ratio of a pseudo thermoplastic resin and a thermoplastic resin having an MFT of 40 ° C. or lower as a base sheet of a decorative panel.
When a resin to be impregnated into the fiber sheet or a thermoplastic resin is mixed, the pseudo thermoplastic resin in the resin mixture is cured by a reaction between an acid and an alcohol, and thus is a formaldehyde-free resin and has a curing temperature of phenol. Therefore, the base sheet impregnated with the above-mentioned pseudo-thermoplastic resin is not yet applied to the surface of the non-woody plant fiber substrate using phenolic resin as a binder. Even if polymerized in the cured state and hot-press molded, the pseudo thermoplastic resin does not adhere to the mold. Therefore, the uncured non-woody plant fiber substrate can be overlaid with the uncured base sheet and hot-pressed at a time.
Usually, after impregnating the pseudo-thermoplastic resin into the fiber sheet, the fiber sheet is heated and dried at a temperature equal to or lower than the curing temperature of the pseudo-thermoplastic resin and stored in a roll form. At this time, in order to improve the flexibility of the resin-impregnated fiber sheet, the pseudo thermoplastic resin includes a resin mixture in which a thermoplastic resin having an MFT of 40 ° C. or less is mixed with the pseudo thermoplastic resin at a ratio of 30% by mass or less. It may be used. At this time, when the MFT of the thermoplastic resin in the resin mixture exceeds 40 ° C., or when a resin mixture in which the content of the thermoplastic resin exceeds 30% by mass is used, the fiber sheet is impregnated with the resin mixture. The heated and dried base sheet becomes hard and roll winding becomes difficult, and the resin mixture may adhere to the mold surface when hot pressing is performed.
The amount of resin mixture impregnated into the fiber sheet is usually ^{20g / m 2 ~150g / m 2} . When the impregnation amount of the resin is less than 20 g / m ^{2 with} respect to the fiber sheet, the smoothness is insufficient, and when it exceeds 150 g / m ² , the roll is difficult to roll or the moldability deteriorates because the rigidity is too high. To do.

Further, when the fiber sheet is replaced with a natural fiber and a synthetic fiber is used, the synthetic fiber is usually a melt-spun thermoplastic resin and is non-porous. When the resin mixture is impregnated into the fiber sheet made of non-porous synthetic fibers in this way, the resin mixture penetrates into the inside of the fiber only by adhering to the non-porous fiber surface constituting the fiber sheet. Absent. On the other hand, natural fibers such as cotton, wood fibers, and vegetable fibers are porous, and when a fiber mixture made of natural fibers is impregnated with a resin mixture, the resin mixture is contained in the fibers constituting the fiber sheet. Can penetrate up to. When the surface of the base sheet is ground after the fiber sheet is bonded to the substrate as the base sheet, in the case of the base sheet made of synthetic fiber, the resin mixture is attached only to the fiber surface. Since the resin mixture is exfoliated from the fiber surface and the fiber appears on the surface of the base sheet, the surface smoothness may be hindered. However, since the base sheet made of natural fibers penetrates into the inside of the fibers as described above, the resin mixture does not peel off from the fibers even by the polishing treatment, and the surface is effectively smoothed. It is.
The smoothness is the surface roughness according to the standard of JIS B 0601 (1994), the arithmetic average roughness (Ra) is 5.0 μm or less, and the maximum height (Ry) is 30.0 μm or less. When the polishing treatment is performed up to, it is possible to prevent appearance defects such as irregularities on the surface of the decorative sheet resulting from the roughness of the fibers of the non-woody plant fiber substrate raw material using the phenolic resin as a binder.
Natural fiber is a material that does not generate a large amount of carbon dioxide gas in the production process like organic synthetic fiber and contributes to measures to prevent global warming, and is desirable as the fiber sheet of the present invention.

  Furthermore, the base sheet impregnated with the resin mixture has good long-term storage stability because the resin mixture is stable in the base sheet for a long period of time. In addition, as described above, the decorative panel of the present invention uses non-woody plant fibers as a substrate material, which contributes to the protection of wood resources.

〔effect〕
Therefore, the present invention can provide a decorative panel that is inexpensive and smooth in appearance with a simple manufacturing process, and also contributes to the protection of wood resources.

Side sectional view of the decorative panel of the present invention

(Fiber sheet)
The fiber sheet of the present invention is used as a base material for a base sheet, and natural fibers are used as the material thereof. Examples of the natural fibers include wood fibers (wood pulp) obtained by mechanical or chemical treatment from hardwoods and conifers, paper, palm fibers, bamboo fibers, kenaf fibers, or seed hair fibers such as cotton and kabok cotton, There are non-woody plant fibers such as bast fibers such as cannabis and flax, vein fibers such as manila hemp and sisal hemp.
The fiber sheet of the present invention may be paper obtained by recycling used paper.
Among these, non-woody plant fibers capable of reducing the fiber diameter are particularly good fibers as natural fibers used in the fiber sheet of the present invention.
When the fiber sheet made of the natural fiber is used as the base sheet base material of the decorative panel, the fiber diameter of the natural fiber is taken into consideration in terms of adhering the decorative sheet to the surface, impregnating the resin, and surface smoothness. The mass per unit area of the fiber sheet (hereinafter also referred to as the basis weight) is preferably 30 to 150 g / m ² and the thickness is 0.02 to 1.0 mm.

(Pseudo thermoplastic resin)
The pseudo thermoplastic resin is
(A) 5 to 100% by weight of a polymer obtained by radical polymerization consisting of an ethylenically unsaturated acid anhydride or an ethylenically unsaturated dicarboxylic acid in which a carboxylic acid group can form an acid anhydride group;
(B) an alkanolamine having at least two hydroxyl groups;
A phosphorus-containing reaction accelerator less than 1.5% by mass with respect to the sum of (A) + (B);
An aqueous binder containing no formaldehyde.
The aqueous binder is generally provided in the form of an aqueous emulsion, an aqueous solution, a water-soluble organic solvent solution such as isopropanol, ethanol, or glycol, or a mixed solvent solution of water and the water-soluble organic solvent. It hardens | cures by esterification reaction of the acid contained in A) and the hydroxyl group contained in alkanolamine (B), water solubility changes to water insolubility, and thermoplasticity changes to pseudo thermoplasticity.
The pseudo thermoplastic resin is currently marketed by BASF under the trade name Acrodur, and there are 950L, DS3530 as an aqueous solution type, and 958D as an aqueous emulsion type.
The above acrodea is crosslinked by the esterification reaction at a temperature of approximately 120 ° C. or higher and is cured at a temperature of 160 ° C. or higher. However, the acrodure has sufficient hardness even in a thermoplastic state before crosslinking and is easy to handle. Moreover, during thermoforming, the hardness is reduced by heating and becomes temporarily thermoplastic (pseudo-thermoplastic), exhibits good moldability, and high molding accuracy is obtained. Moreover, since the cross-linking of the acrodure is based on an esterification reaction, there is an advantage that only water is by-produced and no harmful substances such as formaldehyde are by-produced.
Two or more of the above-mentioned pseudo thermoplastic resins, for example, an aqueous solution type and an aqueous emulsion type may be mixed, or other thermoplastic resin aqueous emulsions and the like may be mixed.
The details of the pseudo thermoplastic resin are described in, for example, JP 2000-506940 A.

(Thermoplastic resin)
The thermoplastic resin used in the present invention has a minimum film forming temperature (MFT) of 40 ° C. or lower. Examples of the thermoplastic resin include acrylic ester resin, methacrylic ester resin, ionomer resin, ethylene-vinyl acetate copolymer (EVA) resin, ethylene-vinyl alcohol copolymer (EVOH) resin, acrylonitrile-styrene-butadiene. Examples include emulsions or aqueous solutions of copolymer (ABS) resins and the like. The mixing ratio of the thermoplastic resin and the pseudo thermoplastic resin is within the range of the pseudo thermoplastic resin: the thermoplastic resin = 100: 0 to 70:30 mass ratio, preferably 100: 0 to 80:20 mass ratio. Is set in the range.

  In the case of a resin mixture of the pseudo thermoplastic resin and the thermoplastic resin, when the MFT of the thermoplastic resin in the resin mixture exceeds 40 ° C., or the content of the thermoplastic resin exceeds 30% by mass When a resin mixture is used, the fiber sheet is impregnated with the resin mixture, and the base sheet that has been heat-dried becomes hard and roll winding becomes difficult. Further, in the case of hot pressing, the resin mixture may adhere to the mold surface. There is.

  The pseudo thermoplastic resin or the resin mixture of the pseudo thermoplastic resin and the thermoplastic resin further includes calcium carbonate, magnesium carbonate, barium sulfate, calcium sulfate, calcium sulfite, calcium phosphate, calcium hydroxide, magnesium hydroxide. , Aluminum hydroxide, magnesium oxide, titanium oxide, iron oxide, zinc oxide, alumina, silica, colloidal silica, mica, diatomaceous earth, dolomite, gypsum, talc, clay, asbestos, mica, calcium silicate, bentonite, white carbon, carbon Inorganic fillers such as black, iron powder, aluminum powder, glass powder, stone powder, blast furnace slag, fly ash, cement, zirconia powder; natural rubber or its derivatives; styrene-butadiene rubber, acrylonitrile-butadiene rubber, chlorop Synthetic rubber such as rubber, ethylene-propylene rubber, isoprene rubber, isoprene-isobutylene rubber; polyvinyl alcohol, sodium alginate, starch, starch derivative, glue, gelatin, blood powder, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, polyacrylate, poly Water-soluble polymers such as acrylamide and natural gums; organic fillers such as wood powder, walnut powder, coconut powder, wheat flour and rice flour; higher fatty acids such as stearic acid and palmitic acid; higher alcohols such as palmityl alcohol and stearyl alcohol Esters of fatty acids such as butyryl stearate and glycerol monostearate; fatty acid amides; natural waxes such as carnauba wax; synthetic waxes; paraffins, paraffin oil, silicone oil, Mold release agents such as kon resin, fluororesin, polyvinyl alcohol, and grease; azodicarbonamide, dinitrosopentamethylenetetramine, P, P′-oxybis (benzenesulfonylhydrazide), azobis-2,2 ′-(2-methyl) Organic foaming agents such as glopionitrile); inorganic foaming agents such as sodium bicarbonate, potassium bicarbonate and ammonium bicarbonate; hollow particles such as shirasu balloon, perlite, glass balloon, foamed glass, hollow ceramics; foamed polyethylene, foamed Plastic foams and foamed particles such as polystyrene and expanded polypropylene; pigments, dyes, antioxidants, antistatic agents, crystallization accelerators, phosphorus compounds, nitrogen compounds, sulfur compounds, boron compounds, bromine compounds, Guanidine compounds, phosphate compounds, phosphate ester compounds, amino compounds Flame retardants such as resins, flame retardants, water repellents, oil repellents, insect repellents, preservatives, waxes, surfactants, lubricants, anti-aging agents, UV absorbers; phthalates such as DBP, DOP, dicyclohexyl phthalate An acid ester plasticizer and other plasticizers such as tricresyl phosphate may be added and mixed.

  Examples of the water / oil repellent include natural wax, synthetic wax, fluororesin, and silicon resin.

[Base sheet]
In the present invention, a resin of 100: 0 to 70:30 mass ratio of the above-mentioned pseudo-thermoplastic resin and a thermoplastic resin having a minimum film forming temperature (MFT) of 40 ° C. or less (if desired, the above-mentioned resin is further added). The above fiber sheet is impregnated with an additive) to form a base sheet.
In order to apply and impregnate the resin to the fiber sheet, the fiber sheet is usually immersed in an aqueous solution and / or an aqueous emulsion of the resin, or is applied by knife coater, roll coater, flow coater, spray coating or the like.
In order to adjust the amount of resin in the fiber sheet impregnated or coated with the resin, after impregnating or coating the resin, the fiber sheet is squeezed using a drawing roll or a press disk.
After impregnating or applying the resin to the fiber sheet, the fiber sheet is heated at room temperature or a temperature of 130 ° C. or lower and dried to prepare a base sheet.
The impregnation amount of the resin is usually 20 g / m ^{2 to} 150 g / m ² , and the thickness of the base sheet is about 0.1 mm to 1.5 mm.
As described above, the base sheet impregnated with the resin is dried at a temperature equal to or lower than the curing temperature of the pseudo thermoplastic resin, and can be easily rolled, and can withstand long-term storage in this state.

(Flame retardants)
Moreover, a flame retardant may be added to the base sheet. Examples of the flame retardant include phosphorus flame retardant, nitrogen flame retardant, sulfur flame retardant, boron flame retardant, bromine flame retardant, guanidine flame retardant, phosphate flame retardant, phosphate ester flame retardant, amino acid Resin-based flame retardant, expanded graphite, etc.
In the present invention, it is particularly desirable to use a powdery solid flame retardant which is hardly soluble or insoluble in water. A powdery solid flame retardant that is insoluble or insoluble in water imparts flame resistance with excellent water resistance and durability to the sound absorbing material. In particular, since the base sheet of the present invention has a rough structure, the powdered solid flame retardant smoothly penetrates into the inside and imparts high flame retardancy or non-flammability.

(Non-woody plant fiber substrate)
In the present invention, from the viewpoint of wood resource protection, non-wood pulp, cotton, palm fiber, hemp fiber, bamboo fiber, kenaf fiber, etc. that grow in a short period of time are used as a material for a decorative panel substrate using the base sheet. Woody plant fiber is used.
And as a binder which binds the said non-woody plant fiber, the phenol-type resin rich in intensity | strength and water resistance is used.

(Phenolic resin)
The phenolic resin is obtained by reacting with an alkali catalyst with an excess of phenol with respect to the phenolic compound and reacting with an acid catalyst with an excess of phenol with respect to the formaldehyde. There are two types of novolacs, but there are also biophenolic resins obtained from biomass. The resole consists of a mixture of various phenol alcohols with added phenol and formaldehyde, and is usually provided in an aqueous solution. The novolak is composed of various derivatives of dihydroxydiphenylmethane based on phenol condensed with phenol alcohol, and is usually provided in powder form.
A desirable phenol-based resin as a binder for the substrate is a phenol-alkylresorcin cocondensate. The phenol-alkylresorcin co-condensate has good stability of the aqueous solution of the co-condensate (initial condensate) and is stored for a long time at room temperature as compared with a condensate (initial condensate) composed only of phenol. There is an advantage that you can. Further, the non-woody plant fiber substrate obtained by impregnating, coating, or mixing the aqueous solution with the above-mentioned non-woody plant fiber substrate has good stability, and the non-woody plant fiber substrate has moldability even when stored for a long period of time. Not lost. Furthermore, alkylresorcin has a high reactivity with formaldehydes and captures and reacts with a free aldehyde, so that it also has an advantage of reducing the amount of free aldehyde in the resin.
The polyhydric phenol mixture obtained by dry distillation of an Estonia oil shale is inexpensive and contains a large amount of various alkylresorcins having high reactivity in addition to 5-methylresorcin. Therefore, it is a particularly preferable polyhydric phenol raw material in the present invention.
In the production of the phenolic resin, a catalyst or a pH adjuster may be mixed as necessary. Furthermore, a hardener such as formaldehyde or an alkylolated triazone derivative may be added to and mixed with the initial condensate (including the initial cocondensate) of the phenolic resin of the present invention. Furthermore, when a water-soluble phenolic resin is used, the phenolic resin may be sulfomethylated and / or sulfimethylated to improve its stability.
The phenolic resin is further added to and mixed with the resin mixture, inorganic, organic filler, release agent, organic-inorganic foaming agent, hollow particles, plastic foam, pigment, dye, antioxidant, Antistatic agents, crystallization accelerators, flame retardants, flame retardants, water repellents, oil repellents, insect repellents, preservatives, waxes, surfactants, lubricants, anti-aging agents, UV absorbers, plasticizers, etc. It may be added.
Two or more of the above substrates may be stacked to form a multilayer substrate.

(Decorative sheet)
Examples of the decorative sheet used for the decorative panel include paper, nonwoven fabric, woven fabric, plastic film, resin-impregnated overlay paper, or a veneer formed by thinly slicing wood with grain.

[Structure of decorative panel]
The structure of the decorative panel of the present invention is shown in FIG.
In the decorative panel 1 shown in the figure, 2 is a substrate, 3 is a decorative sheet, and 4 is a base sheet interposed between the substrate 2 and the decorative sheet 3.

[Manufacture of decorative panels]
In order to produce the decorative panel of the present invention, for example, the phenolic resin is first mixed with the non-woody plant fiber. The phenolic resin is mixed as an initial condensate. Usually, the said phenol-type resin initial stage condensate is added in the range of 10 mass%-100 mass% with respect to the said non-woody plant fiber.
The non-woody plant fiber to which the phenol-based resin initial condensate is added is, for example, distributed on a forming belt conveyor or a former and formed into a mat shape. If desired, the non-woody plant fiber formed into the mat shape is The fibers are intertwined by the needle punching, and the mat strength is improved.
The obtained mat-like non-woody plant fiber is coated and impregnated with the above-mentioned phenolic resin by spraying, impregnation, spreading, etc., and dried by heating at about 120 ° C. to 150 ° C. until the phenolic resin is in a B state. It is considered as the substrate fabric.
Next, the base sheet is polymerized on the substrate substrate, and hot-pressed into a predetermined shape at a heating temperature of 160 ° C. to 220 ° C. for about 1 minute to 10 minutes. The surface of the base sheet that has been hot-pressed has a surface roughness according to a measuring method of JIS B 0601 (1994) by a polishing process such as buffing or sanding, and an arithmetic average roughness (Ra) of 5.0 μm or less and After the maximum height (Ry) is 30.0 μm or less and the surface is smoothed, a decorative sheet is bonded onto the base sheet.

Adhesion between the original substrate and the base sheet may be performed by a phenolic resin impregnated in the original substrate and / or a resin impregnated in the base sheet. It may be carried out by interposing a thermoplastic resin such as a resin emulsion or synthetic resin dispersion, a hot melt adhesive powder spreading layer, a hot melt adhesive film, or the like.
Furthermore, the adhesion between the base sheet and the decorative sheet is an emulsion such as rubber, acrylic, vinyl acetate, ethylene-vinyl acetate, urethane, aqueous vinyl, polyamide, polyester, etc., aqueous solution, film, powder, etc. This is done using a normal adhesive.

  Examples for describing the present invention more specifically will be described below, but the present invention is not limited to these examples.

[Manufacture of substrates]
As non-woody plant fiber, kenaf fiber (fiber length: 50 mm to 80 mm, average fiber diameter: 50 μm to 150 μm) is formed into a mat shape on a former, and mass per unit area is 1000 g / m ² , thickness by needle punching method. An 8 mm non-woody plant fiber mat was prepared.
Next, a resol-type phenol-formaldehyde initial condensate (solid content 50 mass% aqueous solution) is applied as a binder to the non-woody plant fiber mat by spraying, and then the application amount is 150 g / m ² in terms of solid content by a squeeze roll. After surplus resin was squeezed into the substrate, the substrate (A) was produced by drying at 120 ° C. while sucking and precuring the impregnated resin.

[Decorative sheet]
As a natural wood veneer, a veneer (B) made of maple material having a thickness of 0.25 mm was used.

[Manufacture of base sheets and decorative panels]
[Example 1]
A fiber sheet (C) made of natural fibers having a thickness of 0.46 mm and a basis weight of 80 g / m ² made of cotton fibers (fiber length 50 to 70 mm, fiber diameter 30 μm) was produced.
A pseudoure 950L (solid content 50% by weight aqueous solution) was used as the pseudo thermoplastic resin, and an acrylic emulsion (solid content 50% by weight) having an MFT of 3 ° C. was used as the thermoplastic resin. The pseudo thermoplastic resin: the thermoplastic resin = 100 After impregnating the fiber sheet (C) with a resin having a blending ratio of 0 to 70:30 by mass so that the solid content is 60 g / m ² and 100 g / m ^2. And dried at 120 ° C. to prepare a base sheet.
Next, two substrates (A) are stacked to form a multi-layer substrate, and each base sheet prepared by the above method is polymerized, followed by hot press molding at 190 ° C. for 4 minutes to form a plate having a thickness of 3 mm. A molded product was produced.
The obtained molded product was allowed to stand at room temperature for 24 hours, and then the surface of the base sheet was subjected to a sanding process, and then the decorative sheet (B) was placed on the base sheet using an ethylene-vinyl acetate adhesive. Adhesive decorative panel No. 1-No. 6 was produced.
Tables 1 and 2 show the state of the surface of the obtained decorative panel, the surface smoothness of the base sheet obtained by sanding the surface, and the test results of press workability during the preparation of the base sheet. Note the fiber coating amount of the resin to the sheet is 60 g / ^{m 2} samples in Table 1, samples of 100 g / ^{m 2} are shown in Table 2.

[Comparative Example 1]
In Example 1, the decorative panel No. was changed in the same manner except that the blending ratio of pseudo thermoplastic resin: thermoplastic resin = 60: 40 mass ratio was used. 7, no. 8 was produced. The test results of the resulting decorative panel are shown in Table 1 and Table 2.

[Comparative Example 2]
A fiber sheet (D) having a thickness of 0.44 mm and a basis weight of 80 g / m ^{2 made} of a polyester fiber (fiber length 50 to 70 mm, fiber diameter 30 μm) in place of the fiber sheet in Example 1 and manufactured by the spunlace method. A base sheet was prepared in the same manner except that the decorative panel no. 9-No. 14 was obtained. The test results of the resulting decorative panel are shown in Table 1 and Table 2.

Test method and evaluation method (surface roughness)
The surface of the base sheet of the laminate formed by hot-pressing the substrate (A) and the base sheet is sanded with a paper file # 400, and the surface of the base sheet after the treatment is JIS B 0601 (1994) surface roughness. Measured accordingly.
(Dressing panel surface condition)
The decorative sheet surface of each obtained decorative panel was visually observed.
A: There is no distortion or unevenness and the appearance is good.
○: Slight distortion is observed when viewed from an oblique direction.
Δ: Distortion and unevenness can be seen from the front.
X: Distortion is large and irregularities are clearly seen, resulting in poor appearance.
(Press formability)
A: Resin does not adhere to the press die and the mold release property is good.
○: There is a little resistance when releasing from the press die, but there is no adhesion of resin.
X: Resin adheres to the press mold and the releasability is poor.

From Table 1 and Table 2, the decorative panel no. 1-No. 3 and comparative panel 2 decorative panel no. 9-No. 11, it can be seen that even if the amount of resin applied to the fiber sheet is the same, the natural fiber allows the resin to penetrate into the fiber, so that there is a difference in the surface roughness of the base sheet. Further, the decorative panel No. 1 of Example 1 in which the application amount of the resin was increased. 4-No. In 6, the surface smoothness is further improved. The decorative panel No. 12-No. No. 14 shows a slight improvement in the surface smoothness by increasing the amount of resin applied, but the decorative panel No. 1-No. Worse than 3. The same applies to the appearance of the decorative sheet surface of the decorative panel.
Further, the decorative panel No. 2 of Comparative Example 2 in which the amount of the thermoplastic resin added is large with respect to the pseudo thermoplastic resin. 7, no. It can be seen that the releasability at the time of press molding is worse at 8.

[Example 2]
For the fiber sheet (C) used in Example 1, Acrodea 958D (solid content 42 mass% emulsion) as a pseudo-thermoplastic resin, and acrylic-styrene copolymer (solid content 42) having an MFT of 35 ° C. as a thermoplastic resin. Mass%), and using the resin with a blending ratio of the pseudo thermoplastic resin: the thermoplastic resin = 70: 30 mass ratio, an application amount of 80 g / m ² as a solid content with respect to the fiber sheet (C). Then, the substrate was dried at 120 ° C. to prepare a base sheet.
Next, two substrates (A) used in Example 1 are stacked to form a multilayer substrate, and the base sheet prepared by the above method is further polymerized, and hot press-molded at 190 ° C. for 4 minutes to obtain a thickness. A 3 mm plate-shaped molded product was produced.
Next, in the same manner as in Example 1, the obtained molded product was allowed to stand at room temperature for 24 hours, and then the surface of the base sheet was subjected to a sanding treatment, and then the above-described makeup was made using an ethylene-vinyl acetate adhesive. A sheet (B) was bonded to prepare a decorative panel.
The surface roughness of the surface of the base sheet subjected to the sanding treatment of the obtained decorative panel has an average roughness (Ra) of 2.4 μm and a maximum height (Ry) of 8.3 μm, which is excellent in press molding workability. The surface condition of the decorative panel was also good.

[Comparative Example 3]
In Example 2, a decorative panel was produced in the same manner as in Example 2 except that the MFT of the thermoplastic resin was 45 ° C.
The obtained decorative panel is hard when the base sheet is produced in the middle of production, wrinkles occur during roll winding and wrinkles occur during press molding with the substrate, and the surface of the decorative panel is uneven even after sanding. The appearance was poor.

  Since the decorative panel using the base sheet of the present invention has a simple manufacturing process and further contributes to the protection of wood resources, it can be used industrially.

1 decorative panel 2 substrate 3 decorative sheet 4 base sheet

Claims (2)

  A fiber sheet made of natural fibers was impregnated with 100: 0 to 70:30 mass ratio of a pseudo thermoplastic resin and a thermoplastic resin having a minimum film forming temperature (MFT) of 40 ° C. or lower. A base sheet characterized by that. The base sheet according to claim 1 is polymerized on a surface of a substrate raw material obtained by mixing a phenolic resin with a fiber containing at least 80% by mass of non-woody plant fiber as a binder, and then hot pressing into a predetermined shape. Then, the phenolic resin in the substrate raw material and the pseudo thermoplastic resin in the base sheet are cured together, and at the same time, the base material and the base sheet are bonded together, and then the surface of the base sheet is JIS B The surface roughness according to the standard of 0601 (1994) was smoothed by polishing to an arithmetic average roughness (Ra) of 5.0 μm or less and a maximum height (Ry) of 30.0 μm or less. A method for producing a decorative panel, comprising adhering a decorative sheet on a base sheet.