JP2010184431A - Woody board which inhibits diffusion of formaldehyde and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a woody board which demonstrates the high capture effect of formaldehyde and does not reduce the physics performance of a woody board, and to provide a method of manufacturing the same. <P>SOLUTION: An adhesion material which includes: an adhesive agent which is a main agent; and a water wax emulsion obtained by the co-emulsification of sebacic acid dihydrazide which is a compound for formaldehyde capture with waxes is applied or is added to a wood chip or a woody fiber to make a molding raw material, and it is hot pressing molded to make a woody board. The sebacic acid dihydrazide is coated with the waxes by co-emulsification, so that the reaction of the formaldehyde in the adhesion agent which is a main agent with the sebacic acid dihydrazide is inhibited before the hot pressing molding. Thereby, the woody board physics performance can be prevented from degradation. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wooden board that suppresses formaldehyde emission and a method for producing the same.

  Formaldehyde-based adhesives (phenolic resin, urea resin, melamine resin) may be used in the manufacture of wood boards such as particle boards, plywood, and wood fiber boards. In this case, free formaldehyde resulting from the formaldehyde-based adhesive may be diffused into the atmosphere from the wooden board, and suppressing the emission of formaldehyde is a problem in the wooden board.

  Therefore, conventionally, urea or hydrazide is applied to a wood chip or wood fiber or added to an adhesive as a so-called formaldehyde collector that reacts with free formaldehyde and collects it ( (See Patent Document 1, Patent Document 2, etc.).

  In particular, in Patent Document 2, a formaldehyde-based adhesive, a formaldehyde-collecting compound containing hydrazides that are powdered or granular at room temperature, and a water-repellent compound containing waxes that are powdered or granular at room temperature are used as woody materials. A method for producing a wooden board is described which is added and heated while applying pressure to the added wooden material. According to this production method, even when a formaldehyde scavenger having a highly hygroscopic compound for capturing formaldehyde is used, water repellent compounds (waxes) that are powdered or granular at normal temperature are It has the effect of melting in the molding process and giving a protective film to the whole wooden board, so that it can prevent the manufactured wooden board from absorbing and expanding and obtain a wooden board with reduced formaldehyde emission Has been.

JP 2002-273145 A JP 2007-38660 A

  The present inventors have continued research and experiment on a wooden board that suppresses the emission of formaldehyde. As described in Patent Document 2, the compound for collecting formaldehyde is powder or granular at normal temperature. And water-repellent compounds containing powdered or granular waxes at room temperature are applied or added to wood materials together with adhesives, and heating while applying pressure to the applied or added wood materials has suppressed the emission of formaldehyde Although a wooden board can be obtained, a formaldehyde-capturing compound that is powdered or granular at room temperature exhibits a formaldehyde-trapping effect at room temperature, so even if it is used with powdered or granular waxes at room temperature, After applying or adding to chips or wood fiber, it is not Aldehyde trapping compound was discovered that reacts with formaldehyde (HCHO) urea resin or melamine resin in the adhesive is the main agent.

  If the reaction between formaldehyde in the adhesive and the formaldehyde-collecting compound occurs before hot pressing, the adhesive ability of the adhesive, which is the main agent, is reduced, and as a result, the physical performance of the manufactured wooden board Was also found to be a sacrifice.

  Furthermore, in the case of using a formaldehyde-collecting compound that is powdered or granular at room temperature and a water-repellent compound containing waxes that are powdered or granular at room temperature, a step of applying or adding an adhesive as a main agent to a wood material; In another process, it is necessary to blend the water-repellent compound with the wood material, and it is inevitable that the process becomes complicated.

  The present invention has been made based on the knowledge obtained by the present inventors described above, and provides a wooden board that exhibits a high formaldehyde-capturing effect and does not deteriorate the physical performance of the wooden board, and a method for manufacturing the same. It is an object to disclose.

  In order to solve the above problems, the present inventors further conducted experiments and research to use sebacic acid dihydrazide as a formaldehyde scavenger and co-emulsify it with waxes. It was found that sebacic acid dihydrazide was unable to exhibit the formaldehyde scavenging function because it became a state covered with waxes (coated state). It was also found that sebacic acid dihydrazide exhibits a formaldehyde scavenging function when the waxes coated by heating run away.

  The present invention has been made based on the above findings, and the wood board according to the present invention is obtained by hot-pressing a molding material obtained by applying or adding an adhesive material to a wood chip or wood fiber. A wood board, wherein the adhesive material is a material containing at least an adhesive as a main ingredient and an aqueous wax emulsion obtained by co-emulsifying sebacate dihydrazide in waxes.

  Further, the method for producing a wood board according to the present invention comprises a wood chip or wood fiber containing an adhesive material containing at least an adhesive as a main ingredient and an aqueous wax emulsion obtained by co-emulsifying sebacate dihydrazide in waxes. It comprises at least a step of applying or adding to form a molding material and a step of hot pressing the molding material.

  In the manufacturing method described above, there is an advantage that the process of forming a molding material can be simplified by using an adhesive material previously mixed with an adhesive as a main agent and an aqueous wax emulsion. However, the present invention is not limited thereto, and the step of forming the molding material includes the step of applying or adding the adhesive as the main agent to a wood chip or wood fiber, and the aqueous wax emulsion before or after the step. You may make it carry out separately to the process of apply | coating or adding to a chip | tip or a wood fiber.

  In the present invention, as the aqueous wax emulsion, an aqueous wax emulsion having a blending ratio of 1 part or less of sebacic acid dihydrazide to 10 parts of wax is preferably used. When the sebacic acid dihydrazide exceeds 1 part with respect to 10 parts of the wax, there may occur a case where the sebacic acid dihydrazide is not sufficiently coated (coated) with the wax even by the co-emulsification treatment. In that case, the formaldehyde in the adhesive, which is the main agent, reacts with dihydrazide sebacate before hot pressing, which is not preferable because the physical performance of the wood board is lowered.

  In the present invention, paraffin wax, microcrystalline wax, montan wax, polyethylene wax, or the like can be used as the wax, and paraffin wax is particularly preferable.

  Moreover, in this invention, it is preferable to perform the said hot press molding at 150 to 200 degreeC. If the temperature is lower than 150 ° C., the exposure of sebacic acid dihydrazide constituting the nucleus is insufficient and the formaldehyde scavenging effect may be reduced, and if the temperature exceeds 200 ° C., the wax may vaporize and ignite.

  By producing a wooden board using an adhesive material containing at least an adhesive as a main ingredient, and an aqueous wax emulsion obtained by co-emulsifying waxes and sebacic acid dihydrazide as in the present invention, It is possible to obtain a wooden board in which dissipation is suppressed and physical performance is maintained.

(1) First, 1 part of sebacic acid dihydrazide having two hydrazide groups in the molecule which is a formaldehyde scavenging compound and 10 parts of wax are co-emulsified by a conventional method to obtain an aqueous wax emulsion. As the waxes, one or more kinds of paraffin wax, microcrystalline wax, montan wax, or polyethylene wax are preferably used. In addition, natural waxes such as carnauba wax, candelilla wax, and ceresin, and synthetic waxes such as polypropylene wax, α-olefin wax, and Fischer-Tropsch wax can also be used.

  Preferably, in the co-emulsification treatment, powdery sebacic acid dihydrazide, which is a formaldehyde scavenging compound, is dispersed in liquefied waxes, and the temperature is lowered. At the time of emulsification during the temperature reduction, an aqueous wax emulsion is formed containing wax particles in which sebacic acid dihydrazide is coated with a wax, with sebacic acid dihydrazide as a core.

(2) Next, according to a conventional method, a wood chip or wood fiber that is a raw material of a conventional wood board is made, and the particle size is optimized by sieving and the like, and then dried. Examples of the wood board to be manufactured include a particle board using a wood chip as a raw material, a wood fiber board represented by HDF and MDF using a wood fiber as a raw material, and the like.

  An adhesive material containing at least the aqueous wax emulsion and an adhesive as a main agent is applied or added to a dried wood chip or wood fiber by a conventional method to obtain a molding material. As an adhesive as a main agent, a resin adhesive used in the production of a conventional wood board can be used as it is. Specifically, a phenol resin, a urea resin, a melamine resin, etc. are mentioned. A resin adhesive to which isocyanate is added may be used. Examples of the isocyanate include diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), hexamethylene diisocyanate (HDI), and the like. The ratio of the adhesive as the main agent and the aqueous wax emulsion is preferably about 50: 1 to 100: 1.

  Note that, as described above, instead of using an adhesive material in which an adhesive that is a main agent and an aqueous wax emulsion are mixed in advance, the step of using the molding material as a base material is made of a wood chip or a wood fiber. It is also possible to divide into the step of applying or adding to the step and the step of applying or adding the aqueous wax emulsion to the wood chip or wood fiber before and after the step.

  A woody board can be obtained by forming the above-mentioned molding material by a conventional method to form a forming mat and then subjecting it to hot-pressure molding by a conventional method. The temperature at the time of hot pressing is preferably 150 ° C to 200 ° C.

  As described above, in the aqueous wax emulsion according to the present invention, sebacic acid dihydrazide, which is a formaldehyde scavenging compound, is covered with waxes, and as such, cannot react with formaldehyde in the main adhesive. When the waxes are washed away from the surface of the sebacic acid dihydrazide due to heating during hot pressing, the sebacic acid dihydrazide exhibits a formaldehyde scavenging function. That is, according to the present invention, before the hot pressing process is performed on the molding material, formaldehyde and sebacic acid dihydrazide in the adhesive which is the main agent do not react with each other. In some cases, the main agent, the adhesive, can exhibit the desired bonding ability without sacrificing the physical performance of the manufactured wood board. Also, sebacic acid dihydrazide continues to exhibit formaldehyde capture.

  Hereinafter, the present invention will be described with reference to examples and comparative examples.

[Example]
(1) Powdered sebacic acid dihydrazide (SDH) as a formaldehyde-collecting compound is added in an amount of 1/10 to heated and melted paraffin wax, and co-emulsified at a reduced temperature to produce an aqueous wax. Emulsion state.

(2) A wooden chip having a dimension of 3 mm or less was prepared as a wooden chip for the surface layer, and a wooden chip having a dimension exceeding 3 mm was prepared as a wooden chip for the inner layer. After drying each, the adhesive material of the mixture ratio shown in Table 1 was applied and mixed to prepare the surface layer molding material and the inner layer molding material. Thereafter, a particle board having a three-layer structure having a thickness of 12 mm was manufactured by a conventional method using the two prepared molding materials. Specifically, on the hot press, the surface layer molding material is first arranged at a thickness of approximately 55 mm, the inner layer molding material is disposed at a thickness of approximately 35 mm, and the surface layer is further formed thereon. After the molding material was placed at a thickness of approximately 55 mm, it was pressed under conditions of a temperature of 170 ° C., a pressure of 25 kg / cm ² , and a time of 165 seconds.

  The particle board obtained by decompression was measured for density, bending strength, wood screw retention, water absorption thickness expansion rate, and formaldehyde emission. The results are shown in Table 1.

[Comparative Example 1]
The surface layer molding material and the inner layer molding material were prepared in the same manner as in Example 1 except that urea was used as the formaldehyde scavenger and powdered wax not containing sebacic acid dihydrazide (SDH) was used as the wax. Using this, a particle board having a three-layer structure was produced in the same manner as in Example 1. About the manufactured particle board, it carried out similarly to Example 1, and measured the density, the bending strength, the wood screw holding power, the water absorption thickness expansion coefficient, and the formaldehyde emission amount. The results are shown in Table 1.

[Comparative Example 2]
(1) An aqueous emulsion obtained by simply mixing 1/10 of sebacic acid dihydrazide (SDH) as a formaldehyde-collecting compound with respect to powdered paraffin wax, and then mixing the resulting emulsion with the wax emulsion A surface layer molding material and an inner layer molding material were prepared in the same manner as in Example 1 except that the three-layered particle board was manufactured in the same manner as in Example 1 except that it was used. About the manufactured particle board, it carried out similarly to Example 1, and measured the density, the bending strength, the wood screw holding power, the water absorption thickness expansion coefficient, and the formaldehyde emission amount. The results are shown in Table 1.

  In Table 1, SL indicates the surface layer and CL indicates the inner layer. SDH is sebacic acid dihydrazide and MDI is diphenylmethane diisocyanate. Moreover, the numerical value in the adhesive material is shown by the addition amount (% by weight) with respect to the absolutely dry wood chip.

[Discussion]
As shown in Table 1, the amount of formaldehyde emitted from the example products is the same value as that of a conventional wooden board (particle board) using urea as the formaldehyde-trapping compound in Comparative Example 1, and the equivalent formaldehyde emission is suppressed. Has an effect.

  Regarding the bending strength and the wood screw holding force, the example product shows a higher value than that of the comparative example 1, and the water absorption thickness expansion rate shows that the example product shows a smaller value than the comparative example 1. This is because, in the present invention, the use of an aqueous wax emulsion obtained by co-emulsifying waxes and dihydrazide sebacate as a part of the adhesive material makes it possible to use a wooden board (particle) without sacrificing physical performance. Board), the effectiveness of the present invention is demonstrated.

  On the other hand, even when using sebacic acid dihydrazide as a formaldehyde scavenging compound, when it is simply mixed as shown in Comparative Example 2 without co-emulsification with paraffin wax, bending strength, wood screw retention, and water absorption There is no improvement in any of the thickness expansion rates. That is, by simply mixing, the sebacic acid dihydrazide is not coated with the wax component, but is present in the adhesive that is the main agent in an exposed state as it is. It is understood that the reaction with formaldehyde in the agent progressed and the curing of the urea resin as an adhesive was inhibited.

Claims (7)

  A wood board obtained by hot pressing a molding material obtained by applying or adding an adhesive material to a wood chip or wood fiber, wherein the adhesive material is a main agent, a wax, A wood board obtained by hot-pressing a molding material characterized in that it is a material containing at least an aqueous wax emulsion obtained by co-emulsifying sebacic acid dihydrazide.   2. The wooden board according to claim 1, wherein the aqueous wax emulsion is an aqueous wax emulsion having a blending ratio of 1 part or less of sebacic acid dihydrazide to 10 parts of waxes. A step of applying or adding an adhesive material containing at least an adhesive as a main agent and an aqueous wax emulsion obtained by co-emulsifying sebacic acid dihydrazide to waxes to a wood chip or wood fiber to form a molding material;
A step of hot pressing the molding material;
A method for producing a wooden board, comprising:   The step of applying or adding the adhesive material to a wood chip or wood fiber to form a molding material, the step of applying or adding the main agent to the wood chip or wood fiber, and before or after that step The method for producing a wooden board according to claim 3, wherein the water-based wax emulsion is divided into a step of applying or adding the aqueous wax emulsion to a wooden chip or a wooden fiber.   The method for producing a woody board according to claim 3 or 4, wherein an aqueous wax emulsion having a mixing ratio of 1 part or less of sebacic acid dihydrazide to 10 parts of wax is used as the aqueous wax emulsion.   The method for producing a wooden board according to any one of claims 3 to 5, wherein the wax is paraffin wax.   The method for producing a wooden board according to any one of claims 3 to 6, wherein the hot pressing is performed at 150 ° C to 200 ° C.