JP2905461B2 - Manufacturing method of odorless special decorative board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an odorless special decorative board, and more particularly, to a JAS. F-1
The present invention relates to a method for producing a odorless special decorative board at a grade (odorless class) level.

[0002]

2. Description of the Related Art Conventionally, formalin-based resin adhesives such as urea resin-based resins and melamine resin-based adhesives have been widely used as adhesives for wood-based boards such as plywood. These adhesives are inexpensive and have good water resistance, but one of their main constituents is formalin, so we used these adhesives to apply an overlay layer to plywood that was cured by heating and pressing. There is a drawback that free formalin is generated from veneer cupboards and other furniture, or floor and vinyl cloth wallpaper and other home interior materials. Recently, with the spread of concrete houses, high airtightness and high insulation type houses with energy-saving design, skin and respiratory organs called "sick house (sick house) syndrome" are considered to be caused by harmful chemical substances from house interior materials. Etc. are coming out. The cause substance is considered to be the above-mentioned free formalin, and it has become a serious living environment problem. Therefore, it is strongly demanded to immediately develop a odorless special decorative board having no formaldehyde odor.

[0003] By the way, when preparing an adhesive liquid for an adhesive for plywood,
The addition of proteins, urea, melamine, resorcin, hydrogen peroxide, sodium sulfite, various amines, etc., which show a binding reaction with free formaldehyde is known in JP-A-48-58032 and JP-B-51-42164. . In the plywood treated by these methods, the amount of formaldehyde released is reduced, and JAS. F-2 and F
-3 grade is satisfactory, but JAS. In order to obtain an F-1 grade (odorless class) level odorless special decorative board, a reduction in adhesive strength and an increase in cost are unavoidable, and in fact, satisfactory products at low cost cannot be obtained. Here, JAS. F grade is a classification of formaldehyde emission specified by Japanese Agricultural Standards. ・ F-1 grade: Average value of formaldehyde emission of sample plywood 0.5 mg / l or less, maximum value 0.7 mg / l or less.・ F-2 grade: same average value 5mg / l or less, maximum value 7
mg / l or less, F-3 grade: same average value 10 mg / l or less, maximum value
It is specified to be 12 mg / l or less.

[0004] The special decorative board includes printed plywood, overlay plywood, and painted plywood. In the case of this overlay plywood, an overlay layer of thin veneer, decorative paper, cloth, etc. is attached to the surface of a wood-based support material such as ordinary plywood with an adhesive, and a resin coating layer is applied as necessary. Heat and pressure treatment. In this case, Japanese Patent Publication No. Sho 51-42165 has been proposed as a method for producing an odorless special plywood with less generation of free formalin. This method is a method for producing a special plywood using a formaldehyde resin as an adhesive for an overlay layer and a surface coating, and after (or before bonding) an overlay layer of veneer, decorative paper, cloth, etc. with a formaldehyde resin adhesive. An aqueous solution of an organic amino compound (weakly alkaline is recommended) is applied to the entire surface of the plywood, and the solution is immersed in the plywood. After drying, the surface is processed with a formaldehyde resin paint. However, since this method needs to capture not only free formalin from the plywood but also free formalin from the adhesive and the surface paint layer, it is necessary to apply and permeate a large amount of an aqueous solution of an organic amino compound, and Since the surface paint layer of the layer is applied in the final stage, free formalin from the paint layer is hard to contact with the organic amino compound aqueous solution applied and penetrated into the plywood, so free formalin from this part is There is a disadvantage that it cannot be completely removed.

[0005]

Therefore, in the above method,
Even though the conditions of JAS: F-2 grade and F-3 grade, which are the Japanese agriculture and forestry standard of the indication classification based on the amount of formaldehyde emission, can be satisfied, they cannot be satisfied as an odorless special decorative board that passes the JASF-1 grade. There is a need.
Under such circumstances, an object of the present invention is to provide a simple method for producing an odorless special decorative board that meets the JAS standard F-1 grade (odorless class) level.

[0006]

As a result of various studies to solve the above-mentioned problems, the present inventor has found that an adhesive other than a formaldehyde resin adhesive is used as an adhesive for bonding an overlay layer, and that an adhesive from the core material is used. A method for producing an odorless special decorative board that efficiently captures free formalin has been completed. That is, the production method of the odorless special decorative board of the present invention is a method for applying and impregnating a formaldehyde-based resin adhesive and overlaying a surface of a wood-based support material such as plywood cured by heating and pressurization with a material other than the formaldehyde-based resin adhesive. When applying the adhesive with the adhesive, the overlay layer is applied and impregnated with a weakly acidic aqueous solution of urea from the back surface of the wood-based support material at the same time or immediately before the application of the adhesive. It is a feature.

In the present invention, it is preferred that the overlay layer has a surface coated with a resin other than a formaldehyde resin in advance. As the overlay layer, printing paper or the like that has not been subjected to a resin coating treatment may be used. In such a case, it is preferable to apply a printing paper and apply an unsaturated polyester resin solution after hot-pressing. As the urea aqueous solution, a weakly acidic aqueous solution in which a weakly acidic substance such as ammonium chloride is dissolved is particularly desirable. Further, the wood-based support material before the overlay layer is attached contains free formaldehyde therein, and the one having a formaldehyde odor corresponding to about F-3 and grade 3 of JAS standard can be used.

Hereinafter, the components of the present invention will be described in detail.
The formaldehyde-based resin adhesive of the present invention means a thermosetting adhesive such as a urea resin-based, melamine resin-based, guanamine resin-based, phenolic resin-based, or resorcinol-based resin containing formaldehyde as a main component. The thermosetting resin precondensate is coated and impregnated on an adhesive surface of a material together with an acidic substance such as ammonium chloride, ammonium phosphate, or sulfamic acid as a curing agent, and cured by heating and pressing.

In the present invention, the wood-based support material such as plywood is formed by applying and impregnating the above-mentioned formaldehyde-based resin adhesive (mainly composed of an initial condensate) onto the bonding surface of the material, and then subjecting the material to a heat and pressure curing treatment. Commercially available products such as bonded plywood, particle board, fiberboard, etc., which contain free formaldehyde therein and whose formaldehyde odor corresponds to the above-mentioned JAS standard F-2, F-3 grade Can be used. Normally, a material which has been subjected to hardening treatment by heating and pressurizing with an adhesive and then subjected to a base treatment by a bottom coater, a reverse coater or a sander process is used.

[0010] Further, as the overlay layer of the present invention,
High quality paper with decorative pattern, resin coated printing paper, vinyl chloride film or sheet with decorative pattern printing, cloth with decorative pattern, thin veneer (veneer) and the like can be used. These overlay layers are preferably coated in advance with a polyurethane resin or an amino alkyd resin.
However, printing paper or the like that has not been coated with such a resin may be used. In this case, the unsaturated polyester resin solution can be appropriately coated in a subsequent step.

In the present invention, as an adhesive for adhering these overlay layers to a wooden support material, various thermoplastic resin adhesives and thermosetting resin adhesives can be used as long as they are other than formaldehyde resin adhesives. No particular limitation is imposed on the vinyl chloride sheet, but ethylene vinyl acetate is used for vinyl chloride sheets, vinyl acetate is used for printing paper, and aqueous is used for printing paper and woodfree paper. An adhesive such as a vinyl urethane resin is preferred. Further, an adhesive such as vinyl acetate is preferably used for a cloth with a decorative pattern, a thin veneer (a veneer) or the like.

In the present invention, when the overlay layer is bonded to the surface of the above-mentioned wood-based support material with an adhesive other than the formaldehyde-based resin adhesive, the wood-based board is simultaneously or immediately before the application of the adhesive. The most characteristic feature is that a weakly acidic aqueous solution of urea is applied and impregnated from the back of the body. In this case, an aqueous solution containing only urea is weakly basic,
It is said to be pH 7.2 for a 10% aqueous solution. By the way, in Japanese Patent Publication No. 51-42165, regarding the aqueous urea solution, the condensation-cured resin is hydrolyzed on the acidic side to release formaldehyde, so that the solution is preferably made weakly alkaline. An aqueous solution of urea alone is applied to the entire surface of the plywood. Accordingly, the above-described method differs from the present invention in that a formaldehyde-based resin adhesive (initial condensate) is applied to the adhesive and the paint of the overlay layer, and that the urea aqueous solution is made weakly alkaline. In the case of the present invention, the effect of trapping free formalin in the plywood is slight, and no remarkable reduction effect is observed even if a simple aqueous solution of urea (weakly alkaline) is applied and impregnated.

In the present invention, free formalin in plywood is reacted with an aqueous urea solution by coating and impregnating with a weakly acidic aqueous solution of urea to form monomethylol urea and dimethylol urea, which are then trapped. It is considered that a condensation reaction occurs in the treatment. In the present invention, a weakly acidic aqueous solution of urea can be adjusted by dissolving an acidic substance in the aqueous urea solution. Here, as the acidic substance, mineral acids such as hydrochloric acid, sulfuric acid, and phosphoric acid, p-toluenesulfonic acid, a sulfuric acid band, acidic salts such as sodium hydrogen phosphate, and ammonium salts such as ammonium chloride, ammonium sulfate, and ammonium phosphate may be used. it can.
The pH at the time of use is preferably a weakly acidic range of about 5 to 7. Particularly preferred acidic substances are ammonium salts such as ammonium chloride, ammonium sulfate, and ammonium phosphate in a weakly acidic aqueous solution which is commonly used as a curing agent for a precondensate of a formaldehyde resin adhesive.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below in detail. In order to apply the overlay layer to the surface of the wood-based support material using an adhesive other than the formaldehyde-based resin adhesive, it is desirable to perform continuous processing on a plurality of rotating rolls or a transfer conveyor. That is, while the wood-based support material is continuously transferred on the rotating roll, the adhesive is applied to the surface of the material from the top, or immediately before that, the weakly acidic aqueous solution of urea is applied to the entire back surface of the material. Impregnate. In this case, as a means for applying and impregnating the weakly acidic aqueous solution of urea over the entire back surface of the wood-based support material, a roller method, a spray method, or a dipping method can be used, but the spray method is preferable. In particular, in order to uniformly apply and impregnate the entire back surface, it is desirable to use nozzles arranged in multiple rows and in multiple stages. Urea is usually
5 to 50%, preferably 10 to 30% aqueous solution is 5 to 50 g / m ²
Apply to an average degree. On the other hand, as a means for applying the adhesive of the overlay layer on the surface, a roller method or a spray method can be adopted, but a roller method is preferable.

In the state where the adhesive is coated on the front surface and the weakly acidic aqueous solution of urea is applied and impregnated from the back surface, the overlay layer is attached to the adhesive layer on the front surface while being pressed by a pressing roller, and then hot-pressed. Press or heating roller
Heat and pressure treatment at about 50-120 ° C. In this case, the temperature conditions of the heat and pressure treatment are required to accelerate the condensation reaction by drying and curing the adhesive and trapping free formaldehyde with urea. In this way, the JAS. An odorless special decorative board of F-1 grade (odorless class) level can be obtained.

[0016]

The present invention will be described below with reference to specific examples. The test method of formaldehyde emission according to Japanese Agricultural Standards used in the following Examples is shown below.・ Preparation of test pieces Prepare 10 rectangular pieces each of 150 mm length and 50 mm width from each sample plywood.・ Test method Size specified in JIS R3503 (glassware for chemical analysis) 2
40mm (volume of 9-11 liters) desiccator with 300ml of distilled water at the bottom 120mm in diameter and 60m in height
A crystal dish of m is placed, and 10 pieces of the sample are fixed on a supporting bracket so as not to come into contact with each other, and left at 20 ° C. for 24 hours to absorb formaldehyde which is emitted into distilled water to obtain a sample solution. .・ Quantification of formaldehyde concentration The concentration of formaldehyde in the sample solution is measured by the acetylacetone colorimetric method.

Example 1 A formaldehyde-based resin adhesive (urea resin-based) was applied and bonded by heating and pressing.
m, back plate 0.60 mm raw plywood made of commercially available Lauan wood (however, the average value of the formaldehyde emission test method for samples collected from five types of plywood according to Japanese Agricultural Standards)
4.9 mg / l, maximum value 5.4 mg / l, JAS: F-2 grade equivalent) as a wood-based support material, and an overlay layer made of printing paper coated on its surface with a polyurethane resin (or aminoalkyd resin) 0.2m
Immediately before applying and attaching a vinyl acetate adhesive, urea 2 in which urea and a trace amount of ammonium chloride are dissolved
0% weak acidic aqueous solution (pH 6.5) 10g / m from the back
It was applied by spraying from a multi-stage nozzle on average so as to be about ² . On the other hand, a vinyl acetate-based adhesive was applied to the surface by a roller method, and then an overlay layer was adhered thereto and hot-pressed at about 100 ° C. with a hot press to obtain a special decorative board. As a result of taking formaldehyde emission test according to Japanese Agricultural Standards by taking samples from four kinds of this special decorative board,
0.4, 0.5, 0.4, 0.5 mg / l, average value 0.45 mg / l
1 and the maximum value was 0.5 mg / l, which was determined to be JAS: F-1 grade equivalent.

Comparative Example 1 A special decorative board was obtained under the same conditions as in Example 1 except that an aqueous solution of urea alone (weakly alkaline at pH 7.3) was used. As a result of taking formaldehyde emission test according to Japanese Agricultural Standards by taking samples from four kinds of this special decorative board, 3.7, 5.5, 4.8, 4.9 mg / l,
Average value 4.7mg / l, maximum value 5.5mg / l, JA
S: F-1 grade was rejected.

[0019]

As described above, according to the present invention, when an overlay layer is applied to the surface of a wood-based support material containing free formaldehyde with an adhesive other than a formaldehyde-based resin adhesive, At the same time or immediately before the application of the urea, the overlay layer is applied and hot-pressed in a state where the acidic aqueous solution of urea is applied and impregnated from the back surface of the wood-based support material, so that the formaldehyde odor is internally contained before the overlay layer is applied. Even if the wood-based support material has a degree corresponding to the above-mentioned JAS standard F-2 or F-3 grade, as a result, the adhesive strength of the overlay layer is reduced for a special decorative board that passes the JAS standard F-1. It can be obtained inexpensively without the need.

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int.Cl. ⁶ , DB name) B27K 5/00 B27D 1 / 04,5 / 00 B29C 51/14 B32B 21/08

Claims (5)

(57) [Claims] 1. When an overlay layer is applied with an adhesive other than a formaldehyde-based resin adhesive to a surface of a wood-based support material such as a plywood bonded with a formaldehyde-based resin adhesive and cured by a curing process, A method for producing an odorless special decorative board, which comprises applying an overlay layer in a state where a weakly acidic aqueous solution of urea is applied and impregnated from the back surface of a wood-based support material simultaneously with or immediately before the application of the adhesive, and subjecting the overlay layer to heat-pressure treatment. . 2. The method for producing an odorless special decorative board according to claim 1, wherein the overlay layer is one whose surface is previously coated with a resin. 3. The method for producing an odorless special decorative board according to claim 1, wherein the overlay layer is coated with a printing paper or the like not subjected to a resin coating treatment and then coated with an unsaturated polyester resin solution after a hot-press treatment. 4. The method for producing an odorless special decorative board according to claim 1, wherein the weakly acidic aqueous solution of urea is obtained by dissolving urea and an ammonium salt in water. 5. The wood-based support material before the overlay layer is attached contains free formaldehyde therein, and the degree of formaldehyde odor is determined by the FAS of JAS standard.
Claim 1 which uses a material equivalent to about two or three grades.
The method for producing the odorless special decorative board according to the above.