JPH1180694A - Resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a wood-fiber board having a good water resisting property and an extremely small amount of formaldehyde emission. SOLUTION: A wood-fiber board contains 55-65 wt.% of a solid material having a mole ratio (F/M) of formaldehyde(F) to melamine(M) of 1.85-2.00, a mole ratio (F/U) of formaldehyde(F) to urea(U) of 3.5-7.0 and a mole ratio (F/Me) of formaldehyde(F) to methanol(Me) of 0.9-3.5, or 55-65 wt.% of a solid material of a mole ratio (F/M) of formaldehyde(F) to melamine(M) of 1.85-2.00 and a mole ratio (F/U) of formaldehyde(F) to urea(U) of 3.5-7.0 which solid material is prepared by adding melamine or urea to an amino resin having a mole ratio (F/M) of formaldehyde(F) to melamine(M) of 2.00-2.40 and a mole ratio (F/Me) of formaldehyde(F) to methanol(Me) of 0.9-3.5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition used for obtaining a wood fiber board having good water resistance and an extremely small amount of released formaldehyde. More specifically, a plate-like, flake-like, fibrous, powdery wood fiber is bonded to a resin composition and molded into a plate shape, and is a wood fiber board composed of multiple layers, and has good water resistance. The present invention relates to a resin composition used for obtaining a wood fiber board having a very small amount of formalin released from the wood fiber board.

[0002]

2. Description of the Related Art Conventionally, when these wood fiber boards are bonded and formed, a formaldehyde-based amino resin such as a urea resin, a melamine resin, and a urea-melamine cocondensation resin is mainly used. However, wood fiberboards using formaldehyde-based amino resin use formaldehyde as part of the raw material, and unreacted formaldehyde remains in the wood fiberboard when cured by heat and pressure. Formaldehyde is released by the progress of hydrolysis and condensation reaction. These formaldehyde move to the surface of the wood fiber board and are released from the board surface and side surfaces. This is the so-called formalin odor, which causes irritation and discomfort. In order to solve these problems of formaldehyde, various measures for reducing formaldehyde in resins have been studied.

[0003] However, it is difficult to achieve a good balance between the formaldehyde emission and the performance such as water resistance, and it is not perfect. Also, a method of storing a wood fiber board in a well-ventilated place and diffusing it over time, a method of applying a compound capable of reacting with formaldehyde to the surface of the wood fiber board after molding,
A method of treating a fiberboard after molding in an ammonia gas chamber has been proposed, but the post-process is complicated and the sustainability of the formaldehyde reduction effect is insufficient. Furthermore, a method of reducing the amount of formaldehyde emission such as a method of painting finish is conceivable, but it is sometimes difficult in practical use, but it is a temporary measure and not a fundamental measure. Therefore, it is conceivable to use a urethane resin containing no formaldehyde at all, an aqueous vinyl urethane resin, an isocyanate, etc., but it is obviously difficult to use it as a general-purpose resin in practice, and the cost is considerably increased.

[0004]

DISCLOSURE OF THE INVENTION The present invention does not require complicated treatment of a wood fiber board, does not lose various strengths and water resistance of the wood fiber board, and can be used in a severe use environment. It is an object of the present invention to provide a resin composition used for obtaining an extremely low amount of wood fiber board with a low amount of formaldehyde emission.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve these objects, and as a result, by using a resin composition of a specific composition as a binder in a wood fiber board having a multilayer structure, They have found that they have good water resistance and can control the amount of formaldehyde released for a long period even under severe conditions.

That is, according to the present invention, the molar ratio (F / M) of formaldehyde (F) to melamine (M) is 1.85.
~ 2.00, the molar ratio (F / U) of formaldehyde (F) and urea (U) is 3.5-7.0, and the molar ratio (F / Me) of formaldehyde (F) and methanol (Me) is A resin composition for obtaining a wood fiber board of 0.9 to 3.5 having a solid content of 55 to 65% by weight with good water resistance and an extremely small amount of formaldehyde released, or a resin composition of formaldehyde (F) and melamine (M) Molar ratio (F / M) of 2.0
Melamine or urea is post-added to an amino resin having a molar ratio (F / Me) of 0.9 to 3.5 between 0 and 2.40 and formaldehyde (F) and methanol (Me), and formaldehyde (F) and melamine are added. Solid content wherein the molar ratio (F / M) of (M) is 1.85 to 2.00 and the molar ratio (F / U) of formaldehyde (F) to urea (U) is 3.5 to 7.0. The present invention relates to a resin composition for obtaining a wood fiber board having a good water resistance of 55 to 65% by weight and a very small amount of released formaldehyde.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The wood fibers referred to in the present invention include wood, stems of Graminaceae, coconut family and the like. In the present invention, a wood fiber is formed into a plate shape, a piece shape, a fiber shape, a powder shape, and formed into a plate shape with an adhesive. .

In particular, in order to impart good water resistance and reduced formaldehyde emission of a molded wood fiber board, the molar ratio (F / M) of formaldehyde (F) to melamine (M) in the resin composition is 1.85 to 1.85. It must be 2.00.
The molar ratio of formaldehyde (F) to melamine (M) (F
If (/ M) is less than 1.85, the curing of the resin composition is slowed, which does not lead to an increase in water resistance, and a large reduction in formaldehyde release cannot be expected. Further, the molar ratio (F / M) of formaldehyde (F) to melamine (M) is 2.00.
If the ratio exceeds the above, problems remain in order to impart water resistance and reduced formaldehyde emission of the molded wood fiber board.

In order to reduce formaldehyde emission from a molded wood fiber board, the molar ratio (F / U) of formaldehyde (F) to urea (U) is 3.5 to 3.5.
7.0. When the molar ratio (F / U) is less than 3.5, it is advantageous for reducing formaldehyde emission from a molded wood fiber board, but it is disadvantageous not only in terms of water resistance and productivity but also a decrease in strength. On the other hand, if the molar ratio (F / U) exceeds 7.0, there is no possibility that the water resistance, productivity, and strength are further improved, but rather, the amount of formaldehyde released from the molded wood fiber board increases, and a reduction is imparted. Problems remain.

In the present invention, the molar ratio of formaldehyde (F) to melamine (M) (F / M) is 2.00 to 2.40, and the molar ratio of formaldehyde (F) to methanol (Me) is (F / Me). Melamine or urea is post-added to the amino resin of 0.9 to 3.5, and the molar ratio (F / M) of formaldehyde (F) to melamine (M) is 1.85 to 2.0.
0, and a resin composition having a molar ratio (F / U) of formaldehyde (F) to urea (U) of 3.5 to 7.0 can be obtained.

Before the post-addition of melamine, the molar ratio (F / M) of formaldehyde (F) to melamine (M) is 2.0
0 to 2.40. If it is less than 2.00 or more than 2.40, the addition of melamine will adversely affect the condensation reaction of the resin composition, fail to provide good storage stability, and leave a problem. Furthermore, a problem arises in that the emission of formaldehyde from the molded wood fiber board is reduced.

The molar ratio (F / U) of formaldehyde (F) and urea (U) may be adjusted in advance without adding urea later, or may be added after addition of formaldehyde (F) and urea (U). The resin composition can be obtained by adjusting the molar ratio (F / U) to 3.5 to 7.0.

In the present invention, the molar ratio (F / Me) of formaldehyde (F) to methanol (Me) is 0.9 to 3.0.
5 When the molar ratio (F / Me) is less than 0.9 or more than 3.5, there is a problem that the condensation reaction of the resin composition is adversely affected and good storage stability cannot be obtained.

In order to impart various properties to the resin composition, other polymers such as polyvinyl alcohol and cellulose derivatives may be used. When necessary, the composition may be used as a composition by mixing with a curing agent, a water-producing agent, a flame retardant, an insect repellent, an antiseptic and the like.

The properties and the production method of the resin composition used in the present invention are not particularly limited, and a production method which is usually applied may be used. ~ 90 ° C is preferred. 60 ° C
If it is less than 1, the desired degree of condensation of the resin composition cannot be obtained, and furthermore, the condensation time is long and disadvantageous in terms of production time. Further, at a temperature exceeding 90 ° C., evaporation of methanol and a change in the condensation form of the resin composition due to the evaporation,
The problem of stable production In addition, the danger increases because of the high temperature in production.

The resin composition of the present invention has a solid content of 55 to 65.
% By weight is required. When the solid content is less than 55% by weight, the amount of water increases when used as a binder, so that there are problems such as heat energy loss at the time of hot pressing, productivity reduction due to prolonged hot pressing time, and increase in residual water content of the wood fiber board. Occurs. On the other hand, if it exceeds 65% by weight, there is a problem that stable production cannot be performed when obtaining the resin composition, change after condensation, and deterioration of handling due to high viscosity occur.

The resin composition can be used as a binder for a wood fiber board composed of multiple layers, for front and back layers, for a core layer, and for all layers. The resin composition uses a catalyst or forms a cured product partially crosslinked by heating to form a high-hardness adhesive layer, which is desirable because the bending strength and rigidity of the obtained wood fiber board are increased.

[0018]

Hereinafter, the present invention will be described in detail with reference to Examples.
The present invention is not limited to these examples. Parts and% represent parts by weight or% by weight unless otherwise specified. Example 1 A reaction vessel equipped with a stirrer, a reflux condenser, and a thermometer was charged with 400 parts of a 43% formaldehyde aqueous solution and 120 parts of methanol, and the pH was adjusted to 11.0.
390 parts of powdered melamine was added, the internal temperature was heated to 85 ° C, and the reaction was carried out at 85 ° C for 120 minutes. Thereafter, 80 parts of urea was added and the mixture was further reacted for 30 minutes. Thereafter, the mixture was cooled to obtain a resin composition (hereinafter abbreviated as a1). Table 1 shows the obtained characteristics of a1.

Next, a wood fiberboard was prepared using a1 under the following method and conditions. Raw wood was used as a wood fiber to make a piece of wood using a flaker and dried to a moisture content of 4%. Next,
The mixture was sieved with a sieve having an opening of 1 mm, the material under the screen was used as the wood fibers for the front and back layers, and the material on the screen was used as the wood fibers for the core layer. Next,
242 parts of the prepared a1 resin, 10 parts of a 50% wax emulsion, 50 parts of water, and 1.0 part of ammonium chloride as a curing agent were mixed, and spray-coated on 1040 parts of wood fibers for the front and back layers. The spraying rate of a1 on the absolutely dry wood fiber was 15%. 450 parts were separated from the wood fibers after application, and used for the surface layer and the back layer. Next, wood fiber 1 for core layer
040 parts, a mixture of 121 parts of the prepared a1 resin, 10 parts of a 50% wax emulsion, 20 parts of water, and 0.5 part of ammonium chloride as a curing agent was spray-coated on the wood fiber for the core layer. The spraying rate of a1 on the absolutely dry wood fiber was 7.5%. 1100 from wood fiber after application
A part was collected and used as a core layer. Next, wood fibers for the back layer were evenly dispersed in a frame of 38 cm square, and subsequently, the fiber mat for the core layer and the surface layer was further dispersed and deposited. Press for 4 minutes at a pressure of ² ,
A wood fiber board having a thickness of 20 mm and a density of 750 kg / m ³ was obtained. Table 1 shows the physical property evaluation results.

Example 2 A resin composition was obtained in the same manner as in Example 1 except that the amount of melamine powder was changed to 376 parts (hereinafter abbreviated as a2). Example 1
A wood fiber board was obtained in the same manner as described above. Table 1 shows the board evaluation results.

Example 3 A resin composition was obtained in the same manner as in Example 2 except that urea was changed to 50 parts (hereinafter abbreviated as a3). A wood fiber board was obtained in the same manner as in Example 1. Table 1 shows the board evaluation results.

Example 4 A resin composition was obtained in the same manner as in Example 2 except that the amount of methanol was changed to 60 parts (hereinafter abbreviated as a4). A wood fiber board was obtained in the same manner as in Example 1. Table 1 shows the board evaluation results.

Example 5 A resin composition was obtained in the same manner as in Example 2 except that urea was changed to 96 parts (hereinafter abbreviated as a5). A wood fiber board was obtained in the same manner as in Example 1. Table 1 shows the board evaluation results.

Example 6 A resin composition was obtained in the same manner as in Example 1 except that urea was changed to 96 parts and methanol was changed to 60 parts (hereinafter abbreviated as a6).
A wood fiber board was obtained in the same manner as in Example 1. Table 1 shows the board evaluation results.

Example 7 A resin composition was obtained in the same manner as in Example 1 except that the amount of melamine powder was changed to 328 parts (hereinafter abbreviated as b1). b1 is 48
After standing at room temperature for a time, add 62 parts of powdered melamine,
For 60 minutes to obtain a resin composition (hereinafter abbreviated as a7). A wood fiber board was obtained in the same manner as in Example 1. Table 1 shows the board evaluation results.

Example 8 A resin composition was obtained in the same manner as in Example 1 except that urea was changed to 30 parts (hereinafter abbreviated as b2). After leaving b2 at room temperature for 48 hours, 50 parts of urea was added and reacted at 85 ° C. for 60 minutes to obtain a resin composition (hereinafter abbreviated as a8). A wood fiber board was obtained in the same manner as in Example 1. Table 1 shows the board evaluation results.

Comparative Example 1 A resin composition was obtained in the same manner as in Example 1 except that the amount of the powdered melamine in Example 1 was changed to 328 parts (hereinafter abbreviated as c1).
A wood fiber board was obtained in the same manner as in Example 1. Table 1 shows the board evaluation results.

Comparative Example 2 Example 1 was repeated except that urea in Example 1 was changed to 150 parts.
A resin composition was obtained in the same manner as described above (hereinafter abbreviated as c2). A wood fiber board was obtained in the same manner as in Example 1. Table 1 shows the board evaluation results.

[0029]

[Table 1]

[0030]

According to the present invention, the wood fiberboard, which has not been achieved by the prior art, has good water resistance and can be released for a long period of time by using a resin composition having a specific composition even under extremely severe use conditions. It has become possible to obtain a wood fiber board capable of controlling the amount of formaldehyde.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Nobuhiko Kotan 7-1-1, Hikoshimasako-cho, Shimonoseki-shi, Yamaguchi Pref.

Claims (2)

[Claims] 1. The molar ratio (F / M) of formaldehyde (F) to melamine (M) is 1.85 to 2.00, and the molar ratio of formaldehyde (F) to urea (U) is 3 (F / U). 0.5 to 7.0 and a solid content of 55 to 65% by weight having a molar ratio (F / Me) of formaldehyde (F) to methanol (Me) of 0.9 to 3.5 with good water resistance and release formaldehyde A resin composition for obtaining an extremely small amount of wood fiber board. 2. The molar ratio of formaldehyde (F) to melamine (M) (F / M) is 2.00 to 2.40, and the molar ratio of formaldehyde (F) to methanol (Me) is (F / M).
/ Me) is post-added with melamine or urea to an amino resin having 0.9 to 3.5, and the molar ratio (F / M) of formaldehyde (F) to melamine (M) is 1.85 to 2.00;
And the molar ratio of formaldehyde (F) to urea (U) (F
/ U) 55-65% by weight of solid content having 3.5-7.0
A resin composition for obtaining a wood fiber board having excellent water resistance and an extremely small amount of released formaldehyde.