JP2008162238A - Aldehydes scavenger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aldehydes scavenger which can reduce a decrease in the bending strength of a wood plate manufactured using an unexpectedly solid-state scavenger which can be added to a wood material before a heat-impressing process or a binding agent and which has an excellent external appearance. <P>SOLUTION: It is the most important feature to contain an aldehyde class scavenging compound which is powder at a normal temperature and solid at one kind or more normal temperatures and one kind or more wood powder. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is an aldehyde collector for collecting aldehydes such as formaldehyde generated from a formaldehyde adhesive, a formaldehyde adhesive containing the aldehyde collector, and further produced using these. The present invention relates to a method for manufacturing a wooden board.

  In the production of wood boards such as particle boards, plywood, and wood fiber boards, it is a common practice to use formaldehyde adhesives as adhesives. In this case, the formaldehyde released from the formaldehyde-based adhesive is released into the atmosphere from the wooden board, which has a problem of harming the environment and health.

Conventionally, as a means for solving this problem, urea, sulfite, and hydrazides are applied to the surface of a wood material as a so-called formaldehyde collector that reacts with formaldehyde and collects it (Patent Document 1). , See Patent Document 2). In this case, the formaldehyde scavenger is usually diluted with water and applied by spray coating, roll coating or the like. The wooden boards are stacked, stored and shipped after applying the formaldehyde scavenger.
Japanese Patent Laid-Open No. 11-240002 JP 2002-331504 A

By the way, after applying the aldehyde scavenger, the wooden board is usually shipped with a thinly polished surface in order to improve the surface aesthetics and to achieve the required dimensions. In particular, when the polishing thickness is large, the amount of the aldehyde trapping agent present on the surface of the wooden board is reduced, and as a result, the problem that the formaldehyde trapping ability is lowered or eliminated by the above-described means arises. As means for solving this problem, a method has been proposed in which sodium sulfite or urea is added as a formaldehyde-collecting component to a wood material to reduce the formaldehyde emission (Patent Document 3).
Japanese Patent Laid-Open No. 10-11010

  However, in the method described in Patent Document 3, sodium sulfite and urea, which are formaldehyde-collecting components, are used by being added to the woody material and adhesive before bonding. It reacted with formaldehyde, a component, to weaken the adhesive strength as an adhesive. For this reason, there existed a problem that the bending strength of the manufactured wooden board fell a little.

  Furthermore, since the sodium sulfite and urea are solid, the added solid sodium sulfite and the like emerge as white spots after the production of the wooden board, which may cause a problem in the appearance of the wooden board. .

  Therefore, in the present invention, it is a solid-state aldehydes trapping agent that can be added to a woody material or adhesive before the hot-pressing process, but the reduction in bending strength of the wood board produced using this is reduced. It is an object of the present invention to provide an aldehyde scavenger capable of producing a wood board having an excellent appearance.

In order to solve the above-mentioned problems, the aldehyde collector of the present invention used by adding and dispersing in a wood material or a formaldehyde-based adhesive,
The most important feature is that it contains a compound for collecting aldehydes and one or more kinds of wood flour which are powders at ordinary temperatures and are solid at one or more ordinary temperatures.

  Since the aldehydes collecting agent of the present invention can be added to the woody material before the hot pressing step, the wood board produced using this can exhibit a high aldehydes collecting effect regardless of the presence or absence of surface polishing. However, it is possible to suppress a decrease in the bending strength of the wooden board, in particular, the bending strength when wet.

  Moreover, the wood flour added to the aldehyde-collecting agent of the present invention masks other components such as aldehyde-collecting compounds in appearance. For this reason, even when the aldehydes-collecting agent of the present invention is used, a type of aldehyde-collecting compound that tends to generate vitiligo or an aldehyde-collecting compound having a large average particle diameter is used. Can suppress the occurrence of vitiligo, and can produce a wood board having an excellent appearance.

  In particular, in an aldehyde collecting agent containing particles obtained by coating a aldehyde collecting compound with a water repellent compound, the aldehyde collecting compound is unevenly distributed through the water repellent compound as a medium. Despite the formation of large vitiligo that could be observed with the naked eye on the surface of the wood board, it was difficult to completely remove such coarse particles. However, due to the masking effect on the appearance of the wood powder, even if coarse particles remain unintentionally on the manufactured wood board, it can be prevented from becoming white spots on the surface of the wood board.

  Also, among the aldehyde collectors of the present invention, the aldehyde collector containing the aldehyde collector compound having a property of generating an acidic gas having reactivity with aldehydes by heating. For example, since the reaction for collecting aldehydes is a gaseous reaction, a high effect of collecting aldehydes can be exhibited. For this reason, the manufactured wood board can obtain the wood board of F ☆☆☆☆ evaluation of JIS regulation which is not subject to use restrictions.

(Formaldehyde adhesive)
The aldehydes collecting agent of the present invention is suitable for use with the above-mentioned adhesive when using a formaldehyde-based adhesive that adheres while releasing aldehydes during use in the production of a wooden board. There is an effect.
Formaldehyde adhesive refers to all adhesives that contain formaldehyde as a component, and typical formaldehyde adhesives include urea and urea-based adhesives (U-based adhesives) based on formaldehyde, melamine, and urea. And a melamine-based adhesive (M-based adhesive) mainly composed of formaldehyde and a phenol-based adhesive (P-based adhesive) mainly composed of phenol and formaldehyde. These formaldehyde adhesives are preferably used for the production of wood boards. In addition, these formaldehyde adhesives and adhesives other than formaldehyde adhesives (for example, isocyanate adhesives) may be used in combination.

(Aldehyde collector)
The present invention relates to an aldehyde collector that is used by adding or dispersing in a wood material or in the formaldehyde adhesive when a wood board is produced using the wood material and the formaldehyde adhesive. Its properties are powder at room temperature. The term “room temperature” is used in a general sense, but strictly speaking, it refers to 25 ° C.

[Average particle size]
In addition, in the aldehyde collector powder of the present invention, in order to impart efficient aldehyde collector ability and improve the appearance of the wood board produced using the aldehyde collector powder of the present invention, The average particle diameter of the powder is preferably 3 mm or less. On the other hand, if the average particle size is too small, not only is it difficult to handle as a powder, but the aldehyde trapping ability may be worsened, or agglomeration may occur and cause an appearance problem. It is preferably 20 μm or more, more preferably 50 μm or more.

[Measurement method of average particle diameter]
The average particle size of the aldehyde-collecting agent of the present invention (mixture powder to which a water-repellent compound, a fluidity improving agent, etc. are added in addition to the aldehyde-collecting compound as necessary) is determined by classification operation and laser diffraction / It shall be measured by a scattering type particle size distribution measuring device.
First, the average particle diameter is measured by classification operation, and when the average particle diameter is 250 μm or more, the average particle diameter value of the powder adopts the measurement value of the classification operation, while the average by classification operation In the case of a powder having a particle size of less than 250 μm, the average particle size is further measured with a laser diffraction / scattering particle size distribution measuring device, and the measured value of the laser diffraction / scattering particle size distribution measuring device is adopted.

Specifically, the classification operation is performed on the object to be measured using a 9-stage sieve and a tray having an opening of 4000 μm, 2830 μm, 2000 μm, 1400 μm, 1000 μm, 710 μm, 500 μm, 250 μm, and 150 μm. In this classification operation, a sieve with a small opening is stacked in the order of a sieve with a large opening, a sample of 100 g / time is placed on the top 4000 μm sieve, a lid is put on, and a low-tap type sieve shaker (( Attached to Iida Seisakusho Co., Ltd., Tapping: 156 times / minute, Rolling: 290 times / minute), and after vibrating for 10 minutes, the sample remaining on each sieve and the saucer was collected for each sieve, This is done by measuring the mass of
When the mass frequency of the tray and each sieve is integrated, the opening of the first sieve where the integrated mass frequency is 50% or more is set to a μm, and the opening of the sieve that is one step larger than a μm is set to b μm. The average particle diameter (weight 50%) of the object to be measured is obtained by the following equation (Equation 1), where c is the total mass frequency from the screen to the aμm sieve and c% is the mass frequency on the aμm sieve.

  On the other hand, in the laser diffraction / scattering particle size distribution measurement, the object to be measured is measured using a particle size distribution measuring apparatus “LDSA-1400A” manufactured by Tohnichi Computer Applications Co., Ltd. Specifically, using a dry dispersion apparatus with a focal length of 300 mm, the laser power is turned on, and after the laser beam is stabilized, automatic focusing is performed. The average particle diameter is measured while continuously sucking the sample powder with a dry dispersion apparatus and adjusting the transmittance ratio between the background and the measurement to a region of 0.5 to 0.9. In the present invention, the average particle diameter obtained by subjecting the measurement result to multiple scattering correction processing on a volume basis is the average particle diameter when the average particle diameter in the classification operation is less than 250 μm.

(Compound for collecting aldehydes)
The compound for collecting aldehydes may be a compound having a known ability to collect aldehydes that reacts with aldehydes. Examples of preferable aldehyde-collecting compounds include sulfites, bisulfites, ureas, hydrazides, and the like. Moreover, you may use the compound for two or more types of aldehydes collection.

  Examples of the sulfites include metal salts such as sodium sulfite, potassium, calcium, and magnesium, amine salts such as monoethanolamine, ammonium salts, and double salts thereof. From the viewpoint of low cost, sodium sulfite, potassium sulfite, calcium sulfite and ammonium sulfite are preferable. In the present invention, one or more of these sulfites can be used in combination.

  Bisulfites include bisulfite, pyrosulfite, and dithionite. Examples of the salt include metal salts such as sodium, potassium, and magnesium, amine salts such as monoethanolamine, and ammonium salts. Of these, sodium salts and potassium salts are preferred. In the present invention, one or more of these bisulfites can be used in combination.

  Examples of ureas include urea and compounds having a urea bond, for example, methyl urea, ethyl urea, dimethyl urea, diethyl urea, guanyl urea, acetyl urea, thiourea, and cyclic urea condensation such as ethylene urea and allantoin. And acyclic urea condensates such as urea dimers such as biuret. In the present invention, one or two or more of these ureas can be used in combination. Among these, preferable examples include urea, ethylene urea, and thiourea, and urea is preferable from the viewpoint of price.

  Examples of the hydrazides include a monohydrazide compound having one hydrazide group in the molecule, a dihydrazide compound having two hydrazide groups in the molecule, and a polyhydrazide compound having three or more hydrazide groups in the molecule. it can. Specific examples of the monohydrazide compound include alkyl hydrazide compounds such as lauryl hydrazide, salicylic acid hydrazide, form hydrazide, acetohydrazide, propionic acid hydrazide, and naphthoic acid hydrazide. Specific examples of dihydrazide compounds include carbodihydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, adipic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide, maleic acid dihydrazide dihydrazide dihydrazide, maleic acid dihydrazide dihydrazide dihydrazide And dibasic acid dihydrazides such as malic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, and dimer acid dihydrazide. Specific examples of the polyhydrazide compound include polyacrylic acid hydrazide. Among these, dibasic acid dihydrazide compounds are preferable, carbodihydrazide, adipic acid dihydrazide, and dodecanedioic acid dihydrazide are more preferable, and adipic acid dihydrazide is more preferable from the viewpoint of price and availability. In the present invention, one or more of these hydrazides can be used in combination.

  Among these compounds for collecting aldehydes, those compounds that are solid at room temperature but have a property of generating an acidic gas having reactivity with aldehydes by heating are preferable. In the case of a compound having such properties, an acid gas having an ability to collect aldehydes is generated in the hot pressing process, and the aldehydes are removed by causing a gaseous reaction with aldehydes such as formaldehyde. For this reason, it is possible to exhibit a higher ability to collect aldehydes than when a compound having other aldehydes collecting ability that removes aldehydes by solid-gas reaction is used.

Specific examples of the acid gas having reactivity with aldehydes include sulfur oxide gas and hydrogen sulfide. Examples of the sulfur oxide gas include SO ₃ gas and the like in addition to typical sulfurous acid gas. When sulfurous acid gas is generated, SO ₃ gas may be generated as a by-product. In the aldehydes collecting agent of the present invention, even when two or more kinds of sulfur oxide gases are mixed and generated as described above, each other does not become an inhibiting factor and both can collect aldehydes and can be preferably used. .
A compound that generates an acid gas having reactivity with aldehydes generates sulfur oxide gas or hydrogen sulfide gas typified by sulfurous acid gas by the following heating reaction. An example will be described in which sodium hydrogen sulfite is used as a compound that generates sulfur dioxide gas by heating, and sodium hydrogen sulfide is used as a compound that generates hydrogen sulfide gas by heating.
2NaHSO ₃ → (Heating) → Na ₂ SO ₃ + H ₂ O + SO ₂ ↑
2NaHS → _{(heating) → Na 2 S + H 2} S ↑

The mechanism by which the acidic gas generated from the compound for collecting aldehydes by the above reaction collects the aldehydes in the hot-pressing process is presumed to follow the following chemical reaction. The case where formaldehyde is used as the aldehyde will be described as an example.
(Sulfurous acid gas)
HCHO + SO ₂ + H ₂ O → HOCH ₂ SO ₃ H—generates unstable acid HOCH ₂ SO ₃ H + Na ₂ SO ₃ → HOCH ₂ SO ₃ Na + NaHSO ₃
(In the case of hydrogen sulfide gas)
H ₂ S + HOCH ₂ OH → HOCH ₂ SH + H ₂ O
In the hot pressing process, the reaction reacts in a gaseous state, so that aldehydes are effectively removed.

Examples of the compound for collecting aldehydes having the property of generating sulfurous acid gas by heating as described above include bisulfites such as sodium hydrogensulfite. Of the bisulfites, bisulfite, pyrosulfite, dithionite and the like are preferable. Examples of the types of the salts include metal salts such as sodium, potassium and magnesium, amine salts such as monoethanolamine, ammonium salts and the like. Depending on the bisulfite, there are compounds that generate SO ₃ gas as a by-product along with sulfurous acid gas by heating. On the other hand, examples of the compound for collecting aldehydes having the property of generating hydrogen sulfide gas by heating include hydrogen sulfide salts such as sodium hydrogen sulfide as described above.

  If it is necessary to more precisely define the term compound having the property of generating an acidic gas having reactivity with aldehydes by heating, in the case where the acidic gas is sulfurous acid gas, It can be strictly defined. That is, the concentration of sulfurous acid gas generation from the compound for collecting aldehydes is a compound of 500 ppm or more when heated at 140 ° C, or a compound that generates sulfurous acid gas, and its decomposition start temperature is 250 ° C or lower, preferably It shall mean a compound of 200 ° C. or lower. This is because if the concentration of sulfurous acid gas generated is too small, the ability to collect aldehydes is not sufficient. In addition, it is considered that a compound having a decomposition start temperature that is too high does not sufficiently generate sulfurous acid gas even at a temperature of about 200 ° C. when bonding is performed in the hot pressing process. On the other hand, in the case of a compound in which the concentration of sulfurous acid gas generated by heating exceeds 50%, it is a compound that is easily decomposed even if it is solid at room temperature, has a strong odor, and is difficult to handle. Not very good.

  Since there is no measurement method established by JIS or the like as a method for measuring the concentration of sulfurous acid gas generated during heating, it was decided to measure by the method described below. The measurement of the thermal decomposition starting temperature is performed under the following conditions.

[Measurement method of sulfurous acid gas concentration]
Test apparatus / instrument: A heat transfer surface corrosion test apparatus described in JIS K 2234-1994 is used. However, the portion corresponding to the metal test piece is made of SUS304 and used as a hot plate.
Test method: After putting 1.0 g of sample from the upper part of the glass cell and enclosing it, the part corresponding to the metal test piece is heated with a heater and heated to the target temperature. After reaching the target temperature, the temperature is maintained for 30 minutes to generate sulfurous acid gas from the sample, and then the stopper at the top of the test apparatus is opened and the sulfurous acid gas concentration is measured with a gas detector tube. A glass cell having an inner diameter of 40 mm and a total length of 530 mm is used. The gas detection tube used was a gas measurement device (sulfur dioxide) manufactured by Gastec Co., Ltd. specified in JIS K0804-1998.

[Pyrolysis start temperature]
Thermal decomposition was performed using TG (TG / DTA 6200 manufactured by SEIKO), and the decomposition start temperature was extrapolated. The temperature raising conditions are as follows.
Temperature range 30-300 ° C
Temperature increase rate: 10 ° C / min

  The results of the above tests are summarized in Table 1. In addition, about the sodium hydrogen sulfite, the density | concentration in the case of the sample amount of 0.1 g was also measured supplementarily. As shown in Table 1, sodium bisulfite, potassium bisulfite, sodium pyrosulfite, potassium pyrosulfite, magnesium sulfite, zinc sulfite and aluminum sulfite are compounds having a sulfurous acid gas generation concentration of 500 ppm or more when heated at 140 ° C., or It was confirmed that the compound generates sulfurous acid gas and has a decomposition start temperature of 250 ° C. or lower. On the other hand, it was confirmed that sodium sulfite and calcium sulfite do not satisfy the above requirements and can be said to be compounds that do not generate acid gas in the present invention.

  In addition, various things can be used for the average particle diameter in the raw material of the compound for aldehydes collection before adjusting to an aldehyde collection agent. A powder raw material having an average particle size that is too large can be used as the aldehyde-collecting compound of the present invention if pulverized by a known means.

Table 2 shows the average particle diameter of commercially available compounds that can be used as the aldehyde-collecting compound in the present invention. Table 2 also shows the average particle size of the pulverized product obtained by pulverizing the commercially available product using a power mill “P-02S” manufactured by Dalton. The pulverization conditions are as follows.
Among Table 2, anhydrous sodium bisulfite and sodium sulfite were passed twice through the power mill equipped with a screen having an opening of 500 μm, and each pulverized product described in Table 2 was obtained. Further, for urea and ethylene urea listed in Table 2, each pulverized product was obtained by passing once through the power mill equipped with a screen having an opening of 500 μm.

(Wood flour)
The wood powder used in the present invention generally refers to a powder produced when wood is crushed. Regardless of the type of wood used as the timber, it may be wood powder from a broad-leaved tree or wood powder from a conifer. Moreover, the thing from a waste wood may be sufficient and the wood powder from the tree of a different kind may be mixed.
If it is the aldehydes collecting agent of the present invention containing the wood powder, compared to the aldehyde collection compound without adding the wood powder of the wood board produced using this, bending strength, in particular The degree of decrease in bending strength when wet is small.
Furthermore, the wood flour exhibits a masking effect on the appearance of the compound for collecting aldehydes in the produced wood board, so that when the wood board is produced using the aldehydes collecting agent of the present invention, An excellent wood board can be obtained.
The preferable content of the wood flour is 0.5 to 60% by weight with respect to the total amount of the aldehyde-type scavenger.

(Additive)
In the aldehydes collecting agent of the present invention, addition of the aldehyde collecting compound and wood flour is essential, but other useful compounds can be further added. Especially, it is preferable to use the said aldehydes collection compound with the below-mentioned water-repellent compound and fluidity improver. Thus, when it contains another compound, it is preferable that content of the said compound for aldehydes collection is 5 to 99 weight% with respect to the total addition amount to a wooden material.

[Water repellent compound]
The aldehyde-collecting agent having the above structure may contain a compound having a large water absorption property such as sodium bisulfite or sodium pyrosulfite as a compound for collecting aldehydes, and this is added as an aldehyde-collecting component. A wooden board made of a wooden material has a drawback that it easily absorbs and expands. Therefore, by further adding a water-repellent compound to the aldehyde-collecting agent having the above-described configuration, it is possible to suppress the water absorption expansion of the wood board manufactured using the compound.

  As the water-repellent compound that can be used in the present invention, known compounds can be used as long as they are solid at room temperature among the compounds having water repellency. Specific examples of preferred water repellent compounds include waxes, silicones, waxes, higher fatty acid metal salts, and the like.

  The waxes include carnauba wax, candelilla wax, montan wax, ceresin, paraffin wax, natural wax such as microcrystalline wax, polyethylene wax, polypropylene wax, α-olefin wax, Fischer-Tropsch wax, and synthetic fatty acid ester. The synthetic wax represented is mentioned. Examples thereof also include oxidized waxes obtained by oxidizing these natural waxes and synthetic waxes, hydrogenated hardened fats and oils (for example, beef tallow hardened oil and castor wax), and modified wax derivatives. Furthermore, waxes made of olefin and maleic anhydride, waxes made of olefin and acrylic acid, waxes made of vinyl acetate or waxes such as higher alcohols, fatty acid amides and polyethers can also be used.

  Examples of silicones include modified dimethyl silicone oil, and examples of higher fatty acid metal salts include calcium stearate, zinc stearate, and aluminum stearate.

  Among these, a water repellent compound having a melting point of 40 ° C. to 140 ° C. is preferable, and a water repellent compound having a melting point of 50 ° C. to 120 ° C. is more preferable. This is because it is easy to obtain a waterproof effect because it is solidified after being melted by the hot pressure during the production of the wood board and dispersed throughout the wood material. Preferred specific examples include natural waxes such as carnauba wax, montan wax, paraffin wax and microcrystalline wax, synthetic waxes such as polyethylene wax, and hardened fats and oils such as beef tallow oil, hardened palm oil, and castor wax. These can be used alone or in combination of two or more.

  When the aldehyde scavenger is produced by the following production method, since the water repellent compound is once melted, it is sufficient that the water repellent compound is solid at room temperature, and its shape is not limited. However, it is also possible to mix and add without depending on the following production method. The properties of the water-repellent compound when mixed and added are powdery, and the particle diameter is preferably 3 mm or less, more preferably 2 mm or less. This is because if the particle size is large, it is difficult to disperse the wood material evenly.

  When the water-repellent compound is used in the aldehyde-collecting agent, the proportion is preferably 5 to 80% by weight, and 10 to 60% by weight based on the total amount of the aldehyde-collecting agent. It is more preferable. This is because if the ratio is too small, the water absorption expansion of the wooden board cannot be sufficiently prevented, while if the ratio is too large, the ability to collect aldehydes, which is the original effect of the aldehydes collecting agent, is lowered. In order to contain the water-repellent compound in the aldehyde-collecting agent, it is sufficient to mix it with other components such as the aldehyde-collecting compound described later by a known method.

  In the aldehydes collecting agent of the present invention, the water-repellent compound is heated and melted instead of mechanically mixing the solid aldehyde-collecting compound and the solid water-repellent compound. Then, when mixed with the compound for collecting aldehydes and cooled, a part or all of the surface of the compound for collecting aldehydes is covered with the water repellent compound. The water-repellent compound coated with the compound for collecting aldehydes has the above-mentioned effect of suppressing water expansion when formed into a wooden board, and the aldehyde collecting agent and formaldehyde adhesive of the present invention are used as a wooden material. When added to, the formaldehyde-based adhesive and the aldehyde-collecting compound come into contact with each other and the adhesive performance is prevented from deteriorating until the wood material is subjected to a hot press molding process. On the other hand, at the time of hot pressing, since the water repellent compound is melted and liquefied to release the aldehyde-collecting compound, formaldehyde emission from the wooden board after hot pressing can be effectively suppressed.

[Flowability improver]
The aldehyde collector of the present invention has fluidity to prevent sticking between the following water-repellent compound particles during production and product storage, and to reduce the angle of repose as a powder, that is, to improve the product fluidity when using the product. It is preferable to contain an improving agent.
Specific fluidity improvers include carbonic acid compounds, silicic acid compounds, and metal soaps. Examples of the carbonate compound include carbonates such as sodium carbonate, calcium carbonate, and magnesium carbonate. Silica compounds include amorphous silica (white carbon), and silicates such as calcium silicate and magnesium silicate, and natural or synthetic zeolite, bentonite, talc, and the like. Mention may also be made of aluminosilicates. Examples of metal soaps include calcium stearate, zinc stearate, and aluminum stearate.
Of these, white carbon, zeolite, calcium stearate, talc and bentonite are preferable. This is because a fluidity improving effect can be obtained more effectively. These compounds can be used alone, but can also be used in combination of two or more.

  The content ratio of the fluidity improver is preferably 0.3 to 10% by weight, more preferably 0.5 to 5% by weight, based on the total amount of the aldehyde-type scavenger. If the content ratio is too small, the particles cannot be effectively prevented from sticking to each other. On the other hand, if the ratio is too large, the intended effect is not improved, and the cost is rather high.

[Other additives]
In the method for producing a wood board of the present invention, in addition to the above-mentioned additives, if necessary, in addition to antioxidants, preservatives, colorants, rust inhibitors, chemicals necessary for the production process should be added. You can also. For example, in order to erase the remaining sulfurous acid gas, a compound having the property of generating basic gas by heating such as urea can be contained, or a basic compound such as calcium oxide or aluminum hydroxide can be added. It can also be added.

(Production method)
[When water-repellent compound is not coated]
Among the aldehyde-collecting agents of the present invention, when the aldehyde-collecting compound is not covered with a water-repellent compound, the aldehyde-collecting compound, wood flour, and other additives can be mixed and mixed by a known method. It can be set as the aldehydes collection agent of invention.

[When water-repellent compound is coated]
Among the aldehydes-collecting agent of the present invention, those containing particles having a water-repellent compound coated on the surface of the aldehyde-collecting compound are subject to at least the following steps (1) to (5). Can be produced with good yield.
(1) Process of melting the water repellent compound
(2) After the step (1), the molten water-repellent compound is brought to a temperature 1-20 ° C. higher than the melting point of the water-repellent compound while stirring and mixing at least the compound for collecting aldehydes and wood flour. And dripping or spraying
(3) Step of cooling the mixture obtained in the step (2) while stirring and mixing
(4) In the step (3), when the mixture is cooled to a temperature lower by 10 to 50 ° C. than the melting point of the water repellent compound, a step of further adding a fluidity improver
(5) Sizing process for obtaining powdery aldehydes collector by sieving the mixture obtained in the step (4)

((1) Process)
Step (1) of the present invention is a step of melting the water-repellent compound in order to drop or spray the water-repellent compound on the aldehyde-collecting compound. A known heater can be used as the heater used for melting.

((2) Process)
The step (2) of the production method of the present invention is a step of dripping or spraying the water-repellent compound melted in the step (1) onto a mixture containing at least an aldehyde-collecting compound and wood flour. The dropping or spraying temperature of the water is 1 to 20 ° C. higher than the melting point of the water repellent compound. For example, when paraffin wax having a melting point of 55 ° C. is used as the water repellent compound, the temperature for dropping or spraying is 56 to 75 ° C. Furthermore, it is more preferable to perform dripping or spraying at a temperature 5 to 10 ° C. higher than the melting point of the water repellent compound. If the temperature at the time of dripping or spraying is too low, the water-repellent compound is solidified and pipe clogging is likely to occur. On the other hand, if the temperature at the time of dripping or spraying is too high, the temperature in the granulator rises, so that the cooling time becomes long and extra energy loss occurs, and adhesion to the walls of the production machine increases.

  In order to control the temperature within a certain range when dropping or spraying as described above, a spray nozzle or dropping for spraying or dropping the melted water repellent compound from the tank in which the water repellent compound to be dropped or sprayed is stored. It is preferable to control the temperature of the system part to the mouth. While controlling the temperature range at the time of dropping or spraying the water-repellent compound in this step, the water-repellent compound is dropped or sprayed on the compound for collecting aldehydes, in particular by spraying, so that the compound for collecting aldehydes, etc. The probability that the composite particles in which the water-repellent compound is coated on the surface of each particle of the mixture containing the compound will increase, and the powdery aldehydes scavenger can have a greater effect of preventing adhesion deterioration. In order to obtain an aldehyde-collecting agent with little component bias, it is preferable to drop or spray the aldehyde-collecting compound, which is an added / sprayed component, while stirring.

((3) Process)
Step (3) of the production method of the present invention is a step of cooling the mixture obtained in step (2) while stirring and mixing. By cooling, the melted water-repellent compound is solidified again.

(Stirring)
The treatment conditions for the agitation in the steps (2) and (3) are preferably such that the agitation fluid number Fr defined by the following formula (i) is 0.1 or more and less than 5.0.
Fr = V / [(R × g) 0.5] (i)
In the equation (i), V represents the peripheral speed [m / s] of the tip of the stirring blade, R represents the rotational radius [m] of the stirring blade, and g represents the acceleration of gravity [m / s ² ]). By controlling the stirring fluid number Fr within the above range, even when a viscous water-repellent compound is selected, it can be uniformly added to the compound for collecting aldehydes. If the Froude number Fr at the time of spraying the water repellent compound is too small, the particles are aggregated and coarse particles are likely to be generated. Moreover, adhesion to the wall of the granulator occurs and the load tends to be excessive, which is not preferable. On the other hand, if the Froude number Fr is too large, that is, the stirring speed is too high, the internal temperature of the granulator rises due to frictional heat caused by stirring, which is not preferable because the cooling time becomes long and energy loss occurs.

((4) Process)
In the step (4) of the production method of the present invention, the fluidity improver is added at the time when the mixture is cooled to a temperature 10 to 50 ° C. lower than the melting point of the water repellent compound in the step (3). It is a process of adding. For example, when paraffin wax having a melting point of 55 ° C. is used as the water repellent compound, the fluidity improver is added when the mixture is cooled to 5 to 45 ° C. Furthermore, it is more preferable to add a fluidity improver when the mixture is cooled to a temperature 20-30 ° C. lower than the melting point of the water repellent compound.

  If the fluidity improver is added before cooling in the step (3), the fluidity improver is taken into the mixture and the outermost surface of the particles is covered with the fluidity improver. Therefore, it does not contribute to improvement of fluidity. Therefore, the fluidity improver is added after the step (3) in which the water repellent compound in the mixture is solidified. Furthermore, by limiting the temperature range to which the fluidity improver is added to a certain range, it becomes easy to obtain particles having a small particle diameter in one pass. In the case where the fluidity improver is not contained, the step (4) is omitted.

((5) Process)
Step (5) of the production method of the present invention is a sizing step in which the mixture obtained in step (4) is sieved to obtain a powdered aldehydes collector. In this step, it is preferable to adjust the particle size so that the average particle diameter of the aldehyde-collecting agent of the present invention is 3 mm or less. It is also possible to grind the powder remaining on the sieving and resize the particles.

(Granulation method and equipment)
The above steps (1) to (4) can be carried out by stirring granulation method, rolling granulation method, extrusion granulation method, crushing granulation method, spray drying granulation method, High-speed mixer, Henschel mixer, Newgra machine, Shugi mixer, Ladyge mixer, Proshear mixer, Ribbon mixer, Spartan mixer, Pug mixer, Turbulizer (above, stirring granulation method) horizontal cylindrical mixer (Rolling granulation method), kneading extruder, horizontal continuous kneader, hermetic compaction processing device (above, kneading extrusion method), countercurrent spray drying tower (spray drying granulation method), etc. Can be done.

  The sizing (sieving) in the step (5) is preferably performed using a low-tap type sieve shaker as described above, but can also be performed using other oscillators, vibrating sieves, and the like. Further, when the powder is pulverized, a power mill, a hammer mill, a pin mill, an airflow pulverizer or the like can be used. Specific examples of the airflow crusher include a wing mill, a jet mill, a zepros, a selenium mirror, and a dream mill.

(Wood board)
Examples of wooden boards obtained by adding a formaldehyde-based adhesive and the aldehyde scavenger of the present invention to a wooden material and bonding them in a hot pressing process include, for example, particle board (PB), OSB, and wooden fiber board ( For example, there are MDF) and plywood. In the case of particle board (PB), the wood raw material is generally made into chips, and after pulverization, it is used after sieving. In the case of OSB, the wood material is cut and used as a strand. In the case of MDF, the wood material is generally made into chips and defibrated for use. In the case of plywood, a board (single board, veneer) obtained by thinly cutting wood is used.

  As raw materials for wood materials, it is obtained by defibrating conifers, hardwoods, wood waste materials (construction demolition materials, furniture and lumber mill ends, waste pallets, packaging waste materials, concrete formwork, sawdust, etc.), sugarcane, coconut shells, etc. Can be used bagasse, annual kenaf, cotton stem etc. Moreover, you may mix glass fiber and organic polymer fiber with the said wooden material.

(Wood board manufacturing method)
In order to manufacture a wooden board using formaldehyde adhesive, generally, after adding formaldehyde adhesive to the wood material (adhesive addition process), the process of bonding the wood material by heating while applying pressure (heat) Pressure process). When producing a wood board using the aldehydes collecting agent of the present invention, prior to the adhesive addition step, it can be used by being contained in a formaldehyde-based adhesive, or before attaching the adhesive or Later or at the same time, it can be added to the side of the wood material to be bonded.

For example, when producing a particle board (hereinafter abbreviated as PB), a relatively finely pulverized wood material is used for the front and back layers, and a relatively coarsely pulverized wood material is used for the core layer. use. After formaldehyde-based adhesive is spray-added into the wood material for the front and back layers, the aldehyde collector is added, mixed for about 5 seconds to 10 minutes with a blender, and uniformly dispersed in the wood material. Similarly, for the core layer, an adhesive and the aldehyde-collecting agent are added. If at least one of the aldehyde collecting agent added to the front and back layers and the aldehyde collecting agent added to the core layer is the aldehyde collecting agent of the present invention, a considerable aldehyde collecting ability can be obtained. More preferably, the aldehyde scavenger of the present invention is added to both layers.
The order of addition of the aldehyde collector is not particularly limited before or after addition of the formaldehyde adhesive, or before or simultaneously with the addition of the formaldehyde adhesive. It is desirable in terms of the process to add an aldehyde scavenger.

  Then, it laminates | stacks on a surface layer-core layer-back layer, and heats it. In heating, heating (hot pressure) is generally performed while applying pressure. The wood material is bonded by hot pressure to form a wood board.

When the aldehyde collector of the present invention is used, the timing at which the aldehydes are released from the formaldehyde-based adhesive and the timing at which the acidic gas having aldehydes-capturing ability is generated substantially coincide with each other in the hot press molding process. Therefore, the generated aldehydes can be collected efficiently.
The temperature and time of the hot pressing process are generally appropriately determined depending on the quality and productivity of the wooden board to be produced, but when using the aldehyde collector of the present invention, the above effects are exhibited. Therefore, the hot pressing temperature is preferably 100 to 300 ° C, and more preferably 140 to 250 ° C. If the temperature is too low, the amount of acid gas generated is small and formaldehyde cannot be collected sufficiently. On the other hand, if the temperature is too high, the quality of the wood board will be burnt, and the quality will deteriorate. The hot pressing time is preferably 60 seconds or longer, more preferably 90 seconds or longer. If the molding time is too short, the temperature inside the wooden board will not rise easily, and the effect of the present aldehyde scavenger will be reduced. The internal temperature of the wood board during hot pressing is preferably 60 ° C. or higher, more preferably 80 ° C. or higher at the central portion in the thickness direction. Moreover, it is more preferable to set it as 100 degreeC or more.
In addition, also when manufacturing a wooden fiber board (MDF) and another wooden board, the said aldehydes collection agent can be added similarly and a wooden board can be manufactured.

  The addition amount of the aldehyde collector in the wood material in the production of the wood board is 0.1 to 20.0% by weight, preferably 0.5 to 10% by weight, more preferably 1.0 to 7.0% by weight. It is. If the amount added is less than 0.1% by weight, the target collecting ability cannot be obtained, and if it is more than 20.0% by weight, the target performance is not improved, leading to an increase in production cost. It is.

  In addition, according to the wood board manufacturing method of the present invention, it is possible to obtain a wood board in which the release of aldehydes is suppressed, but the compound further has an ability to collect aldehydes with respect to the wood board obtained through the above steps. Can also be applied as an aqueous solution.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to only the following Examples. In each example, unless otherwise specified, parts and% are based on mass.

(Example 1)
[Adjustment of aldehyde collection agent]
High-speed mixer (Fukae Powtech Co., Ltd.), powdered anhydrous sodium bisulfite (Daito Chemical Co., Ltd. average particle size 190μm) 55 parts and hardwood wood flour ("LIGNOCEL HB120" (J.RETTENMAIER & SOHNE GMBH + 14 parts), 30 parts of hardened palm oil having a melting point of 58 ° C. (“IHP-58” manufactured by Miyoshi Oil & Fats Co., Ltd.) is melted and sprayed on the anhydrous sodium bisulfite at 70 ° C., Granulation was carried out under a granulation condition where the stirring fluid number Fr was 1.1. Next, until the temperature of the powder reaches 40 ° C., the powder is cooled while maintaining the stirring condition with a stirring fluid number Fr of 1.1, and the aldehyde scavenger in the manufacturing apparatus is collected, and the collected sample After confirming that the temperature reached the cooling temperature (40 ° C.), 1 part of white carbon carplex # 67 (manufactured by DLS JAPAN) was added. Finally, in a power mill P-02S (manufactured by Dalton Co., Ltd.), the particle size was set to a maximum of 3 mm, and pulverization and sizing were carried out to obtain an aldehyde scavenger.

  The aldehyde scavenger obtained by the above operation is classified using a 9-stage sieve and a tray having a mesh size of 4000 μm, 2830 μm, 2000 μm, 1400 μm, 1000 μm, 710 μm, 500 μm, 250 μm, and 150 μm, and 2830 to 500 μm The aldehyde collection agent classified into the above was used as the aldehyde collection agent of Example 1. The average particle size of the aldehyde collector of Example 1 was 1.1 mm.

(Preparation of adhesive)
A urea / melamine copolycondensation adhesive (nonvolatile content 65%, formaldehyde molar ratio 1.3), 55% wax emulsion, ammonium sulfate and water as curing agents, 20 parts, 1 part, 0.5 parts, 5 parts, respectively. The adhesive used for an Example and a comparative example was prepared by mixing in the ratio of the part.

[Addition to wood materials]
Wood raw materials such as wood chips are pulverized with a flaker, sieved with a sieve with an opening size of 1.7 mm, the wood material under the sieve is the wood material for the front and back layers, the wood material on the sieve is the wood material for the core layer did. The sieved woody material was dried in a hot air dryer at 90 ° C. to make the water content 3% or less.

30 parts of the prepared adhesive was spray-coated on 100 parts of the wood material for the front and back layers dried by the above operation and mixed uniformly. Thereafter, 2.5 parts of the aldehyde scavenger of Example 1 was further added and mixed to obtain a woody material for the front and back layers. Next, with respect to 100 parts of the wood material for the core layer, the same operation as that for the front and back layers except that the prepared adhesive was changed to 12 parts and the aldehyde scavenger of Example 1 was changed to 1.5 parts. The woody material for the core layer was obtained by the operation.
Next, 200 parts of the wood material for the back layer, 750 parts of the wood material for the core layer, and 200 parts of the material for the surface layer are sequentially laid on a 30 cm square formwork, sandwiched between 220 ° C. hot plates and 200 kg at a pressure of 30 kgf / cm ^2. Heat-pressed for 2 seconds to obtain a wood board of Example 1.

[Evaluation 1: Emission amount]
The amount of formaldehyde emitted from the wood board of Example 1 obtained above was determined in accordance with the desiccator method according to the test method for formaldehyde emission from particle boards (JIS A 5908: 2003) and building boards (JIS A 1460: 2001). Was collected and measured.

[Evaluation 2: Appearance]
In the appearance test, the surface of the wood board obtained after hot press molding was visually observed, and the presence / absence, size, amount, etc. of vitiligo were examined and evaluated. The evaluation criteria are as follows.
A: Good (cannot detect vitiligo)
○: Slightly small white spots △: A large amount of fine white spots or slightly large white spots ×: A large amount of large white spots

[Evaluation 3: Bending strength]
The bending strength test was performed according to the bending strength A test when wet according to JIS A 5908: 2003.

(Comparative Examples 1-2)
It was set as the wooden board of the comparative example 1 manufactured in the procedure similar to Example 1 except not having added wood powder to the aldehydes collection agent. Moreover, it was set as the wooden board of the comparative example 2 manufactured in the procedure similar to Example 1 except not having added an aldehydes collection agent.

The results of Example 1 and Comparative Examples 1 and 2 are shown in Table 3 above.

  The aldehyde-collecting agent of the present invention and the formaldehyde-based adhesive to which the above components are added are used as an additive or an adhesive itself to be added to a wooden material or an adhesive when the wooden material is bonded with the formaldehyde-based adhesive. There is the above usability. The wood board manufacturing method of the present invention has industrial applicability as a manufacturing method of particle board, plywood, and wood fiber board having excellent appearance and less formaldehyde emission and excellent appearance.

Claims (5)

  An aldehyde collector that is added to and dispersed in one or both of a woody material and a formaldehyde adhesive, and the aldehyde collector is one or more kinds of aldehydes that are solid at room temperature A powdery aldehyde collector that contains a compound for collection and one or more types of wood flour.   2. The aldehyde collection agent according to claim 1, wherein the aldehyde collection compound has a property of generating an acidic gas having reactivity with the aldehyde upon heating.   The aldehyde collector according to claim 1 or 2, wherein the aldehyde collector further contains one or more water-repellent compounds.   At least a step of adding the aldehyde scavenger described in any one of claims 1 to 3 to either one or both of the woody material and the formaldehyde adhesive, and then hot pressing. A method for producing wood board.   A wood board in which a wood material to which at least a formaldehyde-based adhesive and the aldehyde-collecting agent according to any one of claims 1 to 3 are added is heat-pressure bonded.