JP2009034855A - Method for producing decorative plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a decorative plate which is free from the discoloration of a woody sliced veneer adhered to the surface of a substrate even when a fiberboard containing iron is used as the substrate in the decorative plate. <P>SOLUTION: A hydrogen peroxide aqueous solution whose concentration is ≥10 wt.% and <30 wt.% and an ammonia aqueous solution whose concentration is ≥26 wt.% and <30 wt.% are mixed to adjust the pH of the mixed solution to be 8.5-9.5. After the mixed solution is applied on the woody sliced veneer to treat it, the woody sliced veneer is stuck on the surface of the fiberboard through an adhesive. The amount of the mixed solution applied on the woody sliced veneer is 140-330 g/m<SP>2</SP>. Preferably, the mixed solution is applied on the woody sliced veneer within 60 min after its preparation. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a decorative board used for a floor, wall, ceiling, etc. of a building, wherein the decorative board is formed by adhering a wooden veneer to the surface of a fiberboard, and more specifically, effectively discoloring the wooden veneer. The present invention relates to a method for manufacturing a decorative board that can be prevented.

  In a decorative board formed by sticking a wood veneer on the surface of a substrate such as a fiber board, the wood veneer is discolored due to aging. This is presumed to be caused by the iron contained in the wood veneer and the alkali and acid adhering to the wood veneer acting on the phenolic component in the wood veneer, causing discoloration, or by the influence of sunlight, fluorescent light, etc. Yes.

  A fiberboard, particularly MDF, is often used as a substrate for a decorative board, and woody wood used in manufacturing this MDF is often used as waste wood from the viewpoint of depletion of wood resources. . MDF made of wood fiber generated from wood waste is used for fastening wood waste with nails, steel fittings, etc., contact with iron claws and buckets of construction machinery that treats wood waste, or adhesion of scattered iron from the outside Inevitably contains iron. For this reason, when using this MDF, in a decorative board manufactured by sticking a wooden veneer on its surface, iron ions in the MDF penetrate into the wooden veneer together with moisture, and phenol components in the wooden veneer, such as lignin It reacts with tannin to produce a black compound, causing discoloration of the wood veneer.

In the production of a decorative board, there is a technique in which a bleaching agent mainly composed of a hydrogen peroxide solution is applied to a wood veneer adhered to a substrate and bleaching is performed in a heated environment (Patent Document 1).
JP-A-8-229903

The bleaching treatment described in Patent Document 1 requires heating using a dedicated heating device, which complicates the manufacturing method and increases the cost.
Therefore, the object of the present invention is to provide a wooden veneer that is adhered to the surface of a veneer board, even when manufacturing a decorative board using a fiber board containing iron such as MDF made of wood fibers generated from waste wood. It does not cause discoloration.

  In order to achieve the above object, the present invention according to claim 1 is a mixture of an aqueous hydrogen peroxide solution having a concentration of 10 wt% or more and less than 30 wt% and an aqueous ammonia solution having a concentration of 26 wt% or more and less than 30 wt%. Then, the pH is adjusted to 8.5 to 9.5, and after treating the wood veneer by adhering this mixed solution to the wood veneer, the wood veneer is attached to the surface of the fiber board via an adhesive. It is the manufacturing method of the fiber board characterized by sticking.

The present invention according to claim 2 is characterized in that, in the fiberboard manufacturing method according to claim 1, 140 to 330 g / m ² of a mixed solution of an aqueous hydrogen peroxide solution and an aqueous ammonia solution is attached to a wood veneer. To do.

  According to a third aspect of the present invention, in the fiberboard manufacturing method according to the first or second aspect, the adhesion treatment to the wood veneer is performed within 60 minutes from the preparation of the mixed solution.

  According to the method of the present invention according to claim 1, since the discoloration generating substance (phenol component) contained in the wood veneer is removed or changed to a substance that does not discolor, the iron ions contained by the iron contained in the fiber board together with moisture Even if it enters the veneer, it will not cause discoloration of the wooden veneer. Although the mechanism for preventing discoloration by the method of the present invention has not been completely elucidated, the addition of ammonia disperses colored substances such as lignin and tannin, which are phenol components in the wood veneer, and is generated by decomposition of hydrogen peroxide. It is presumed that these colored substances are oxidized and decomposed by oxygen and lightened to such an extent that the original color tone of wood is not lost.

  Since the concentration of the aqueous hydrogen peroxide solution in the treatment liquid for the wood veneer can be suppressed to a relatively low concentration of 10% by weight or more and less than 30% by weight, it is necessary for adjusting the pH of the treatment liquid to 8.5 to 9.5. A small amount of aqueous ammonia solution is sufficient with respect to the aqueous hydrogen peroxide solution (several tenths to several hundredths, data shown in Table 1).

  Furthermore, since the concentration of the aqueous hydrogen peroxide solution is relatively low, the decomposition of the hydrogen peroxide itself proceeds slowly, and the time margin until the mixed solution adheres to the wood veneer (several tens of minutes. Table 2) Data description).

  In addition, since the decomposition of hydrogen peroxide proceeds relatively slowly after the mixed solution adheres to the wooden veneer, the time for the mixed solution to penetrate into the wooden veneer can be secured sufficiently and penetrates uniformly. Change the color change-generating substance to a non-color change-generating substance over the entire veneer to prevent uneven color and discoloration.

  Furthermore, since the pH of the mixed solution is adjusted to weak alkaline 8.5 to 9.5 and is attached to the wood veneer, so-called alkali burning does not occur.

  Further, when the mixed liquid is attached to the wood veneer, it is not processed in a heating environment, so that the apparatus configuration can be simplified and the processing efficiency can be improved.

According to the method of the present invention according to claim 2, by setting the adhesion amount of the mixed liquid to the wooden veneer to be 140 to 330 g / m ² , it reacts with the color change generating substance contained in the wooden veneer as necessary and sufficiently, and the color change occurs. Substances can be efficiently removed or converted into non-discoloring substances.

  According to the method of the present invention according to claim 3, since the adhesion treatment to the wooden veneer is performed within 60 minutes from the preparation of the mixed solution, the time from the adhesion treatment of the mixed solution to the wooden veneer until the end of the reaction is 40 minutes. (Data is listed in Table 2). If there is a large amount of wood veneer during the reaction process, the work space will be occupied more than necessary, and the process will be complicated and the yield will be reduced, but according to the method of the present invention, the reaction will be completed within 40 minutes. So it does not cause such harmful effects.

  First, details of each requirement of the method of the present invention will be described.

  The aqueous hydrogen peroxide solution is adjusted to a concentration of 10 wt% or more and less than 30 wt% by diluting the aqueous hydrogen peroxide solution with water. If the concentration of the aqueous hydrogen peroxide solution is less than 10% by weight, the concentration of the aqueous solution is low, so that a large amount of the aqueous solution is required and the handling becomes difficult. When the concentration of the aqueous hydrogen peroxide solution is 30% by weight or more, the aqueous solution concentration is too high, and oxygen generation accompanying the decomposition of the hydrogen peroxide proceeds rapidly and in a short time until the mixed solution adheres to the wood veneer. In this case, sufficient time margin cannot be given, and even after the adhesion treatment, the penetration into the wooden veneer is too rapid and uniform, causing uneven color.

  The concentration of the aqueous ammonia solution is 26% by weight or more and less than 30% by weight, preferably 28% by weight.

  The pH of the mixed solution is adjusted to 8.5 to 9.5. When the pH is less than 8.5, the decomposition of the aqueous hydrogen peroxide solution is reduced, and the reactivity with the wood veneer is lowered. When pH exceeds 9.5, it will become easy to produce the alkali contamination with respect to a wooden veneer.

  The mixed liquid is attached to the wood veneer by application, immersion (dipping), or the like by rollers, brushes, spraying, or the like.

The amount of the liquid mixture to be adhered to the wood veneer is preferably 140 to 330 g / m ² . When the adhesion amount is less than 140 g / m ² , the adhesion amount per unit area is small and whitening becomes insufficient. If the adhesion amount exceeds 330 g / m ² , whitening is sufficiently performed, but hydrogen peroxide remains and causes color unevenness.

  The mixed solution may be subjected to a time (elapsed time) from the concentration adjustment to the adhesion within 60 minutes, preferably within 30 minutes. If the elapsed time is within 60 minutes, the reaction activity (or bleaching performance) of the mixed solution is maintained, and the time for reaction with the discoloration-generating substance contained in the wood veneer is finished within 40 minutes. If the elapsed time is within 30 minutes, the reaction activity (bleaching performance) is more effectively maintained.

  The adhesive for adhering the wood veneer to the fiberboard is not particularly limited as long as it does not affect the discoloration of the wood veneer. For example, aqueous vinyl acetate resin, ethylene vinyl acetate resin, urea resin, melamine resin , Phenol resin-based, water-based vinyl urethane resin-based or their modified resin adhesive, or isocyanate-based adhesive, synthetic rubber-based, nitrile rubber-based, etc. .

  The decorative board of the present invention is used for a floor, a wall, a ceiling, and the like, and has a wood fiber board and a wood veneer bonded to the surface.

  The fiberboard is stipulated in JIS A5905: 2003, including insulation fiber board (or insulation board, symbol IB), medium density fiber board (sign MDF), hard fiber board (or hard board, symbol HB) However, MDF is particularly optimal.

  As an example of a fiberboard manufacturing method, wood fibers are blown and dried through a duct to adjust to a predetermined moisture content, and then transported to a mixing device, and an adhesive is added to the wood fibers in the mixing device. Mix to obtain a mixture. The addition of the adhesive may be performed in the duct when the air is sent after defibration. Next, the mixture is blown and uniformly dispersed on a conveying device by a forming device to form a continuous mixture mat having a constant thickness. The obtained mat is cut to a fixed length, and then inserted into a hot press to perform hot press molding. The surface of the obtained fiber base plate is sanded as necessary to obtain a fiber plate.

The hot pressure conditions at this time are generally performed in each range of a pressure of 10 to 30 kgf / cm ² , a temperature of 110 to 220 ° C., and a time of 1 to 20 minutes. The optimum conditions are determined by the type, dimensions, purpose of use, etc. of wood fibers and adhesives.

  As the adhesive added to the wood fiber, one or more kinds selected from thermosetting adhesives such as urea, phenol, melamine, urethane and other resins or their modified resins, isocyanates and synthetic rubbers are used. To do.

  Wood fibers are softened by condensing softwood such as pine, cedar and cypress, and hardwood such as lauan, capol, chestnut, poplar, and willow by steaming one or more wood chips with high-temperature and high-pressure steam. It is obtained by defibration with a fiber device. The length and thickness of the wood fiber are, for example, about 0.4 to 40 mm, and the diameter is about 0.05 to 0.5 mm (aspect ratio 10 to 400). Furthermore, the fiberboard used for this invention can also use the wood fiber obtained from the wood chip produced | generated from the wood waste material as a raw material. A fiberboard made from wood fibers obtained from wood waste chips inevitably contains a lot of iron.

  The wood veneer is obtained by thinning the flitch. Flitch made a large block by gathering multiple wood boards or squares of tree species such as beech, hippopotamus, oak, cherry, oak, teak, etc. under pressure, using an adhesive, and thinning this large block Is. The thickness of the wood veneer is about 0.15 to 0.8 mm.

  Examples of the method of the present invention will be described below with reference to comparative examples.

Table 1 shows the test results showing the relationship between the concentration and amount of each component of the mixed solution, the color unevenness of the wood veneer, the presence / absence of discoloration, and the exothermic decomposition rate of the reaction. Example 1 in Table 1 is a mixture of 293 parts by weight of a 10% aqueous hydrogen peroxide solution and 1 part by weight of an aqueous 28% ammonia solution to obtain a pH 9 mixture, and this mixture is used as a unit surface of a wood veneer. It is a case where it apply | coats by 327g per (m < ² >). The curing period after application of the mixed solution is 3 to 4 days at room temperature (20 ° C.). Thereafter, in order to further test for the presence of uneven color and discoloration, a 1% NaOH aqueous solution was sprayed at a rate of 163 g / m ^{2 on} the surface of the wooden veneer.

In Examples 2 and 3 and Comparative Examples 1 and 2, the mixed veneer adjusted to pH 9 with each component concentration and amount of the mixed solution shown in Table 1 was applied to the wood veneer with the applied amount shown in Table 1. The surface of the wood veneer was sprayed with a 1% NaOH aqueous solution at a rate of 160 to 170 g / m ^{2 in} the same manner as in Example 1.

  Regarding color unevenness, Examples 1 to 3 and Comparative Example 1 were “good” (◯ mark), and Comparative Example 2 was “a little” (Δ mark). Regarding discoloration, “None” was given for Examples 1 to 3 and Comparative Example 2, but “Yes” was given for Comparative Example 1. The exothermic decomposition rate of the reaction was “slow at low temperature” in Examples 1 to 3 and Comparative Example 1, and “slow at high temperature” in Comparative Example 2. From these test results, it was confirmed that all of Examples 1 to 3 had good color unevenness and no discoloration, so that the processing conditions for the wood veneer were optimal. Comparative Examples 1 and 2 were insufficient in terms of color unevenness or discoloration, and could not be evaluated as having appropriate processing conditions.

  Table 2 is a table showing the relationship between the time from preparation of the mixed solution to use and the reaction end time from the time when the mixture is attached to the wood veneer until the reaction is completed. The longer the elapsed time, the more the mixed solution pH shifts to the neutral side, and the mixed solution temperature rises. The reaction end time becomes longer as the elapsed time becomes longer. It can be seen that if the tolerance of the reaction end time during production is 40 minutes or less, the time from the preparation of the mixed solution to its use may be 60 minutes or less.

Claims (3)

Adjust the pH to be 8.5 to 9.5 by mixing an aqueous hydrogen peroxide solution with a concentration of 10 wt% to less than 30 wt% and an aqueous ammonia solution with a concentration of 26 wt% to less than 30 wt%. A method for producing a fiberboard, comprising: treating the wood veneer by adhering the mixed solution to the wood veneer, and then sticking the wood veneer to the surface of the fiber board with an adhesive. The mixed solution of aqueous hydrogen peroxide solution and aqueous ammonia solution, characterized in that to 140~330g / m ² is deposited against wood veneer, method for producing a fiber board according to claim 1, wherein. The method for producing a fiberboard according to claim 1 or 2, wherein the adhesion treatment to the wood veneer is performed within 60 minutes from the preparation of the mixed solution.