JP3442212B2 - Wood fiberboard manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a wood fiberboard, and more particularly to forming a hard layer on at least the surface layer of a wood fiberboard such as MDF (medium fiberboard) and HB (hardboard). The present invention relates to a method for manufacturing a wood fiberboard.

[0002]

2. Description of the Related Art Wood fiber boards such as MDF and HB are mainly made of urea resin, which is a vegetable fiber obtained by defibrating wood.
It is manufactured by forming a fiber mat using a formalin resin such as a melamine resin or a phenol resin as an adhesive, and heating and pressing the mat. Since such a wood fiber board has an appropriate light weight and bending strength, it is widely used alone as a base material of a decorative board or in the form of a laminate with another wood material such as plywood. Then, a surface decorative material is attached to the surface of the wood fiber board via an adhesive such as urea melamine resin, ethylene vinyl acetate resin, SBR, and water-based vinyl urethane to obtain a decorative plywood.

As described above, formalin-based resin is mainly used as an adhesive in the production of wood fiberboard, but formalin-based resin is a thermosetting resin that is three-dimensionally hardened, and thermoset formalin-based resin is , Has physical properties that are hard and brittle among synthetic resins. Therefore, the conventional wood fiberboard,
When an external force such as an impact force is applied to the fiber adhesive layer, the adhesive layer is destroyed, and the wood fiber board is liable to be chipped or delamination is likely to occur.

On the other hand, for the purpose of improving the bending resistance of the wood fiberboard, a thermosetting resin (for example, phenol resin) is applied on both sides of the wood fiberboard using a spreader, and then the phenol resin is By inserting the coated wood fiberboard between the upper and lower presses of the hot press and heating it, a resin impregnated layer in which the phenol resin has been impregnated and hardened is formed on the front and back surfaces of the wood fiberboard, which makes it lightweight. There is known a wood fiber board whose bending strength is strengthened as compared with that before heating (see JP-A-7-80810).

[0005]

As described above, in the wood fiberboard, the adhesive layer is destroyed when an external force such as an impact force is applied to the fiber adhesive layer, and the wood fiberboard is likely to be chipped or delaminated. Therefore, in a production line for manufacturing a decorative board by using a wood fiber board or a composite board thereof as a base material and adhering a thin veneer board or the like on the base material, the wood fiber board or the composite board is guided particularly in a flow direction changing line or the like. There is a drawback in that the wood fiberboard is partially chipped when it comes into contact with a rod or the like or when another unexpected impact force is applied to the surface of the wood fiberboard. When the chipping occurs partially, the base material is discarded as a defective product, which is one of the causes of cost increase. Further, when a caster test or the like is performed on a decorative board having a wood fiber board or a composite board thereof as a base material, or when a V groove or the like is formed on the surface of the decorative board for the purpose of design, the V groove portion or the like is pressure-welded. There was also a defect that the part was delaminated. Therefore, a wood fiberboard having high impact resistance is required.

Further, the dimensional change of the wood fiberboard due to moisture is larger than that of the plywood, and when the wood fiberboard and the plywood are bonded together to form a wood fiber composite board, there is a problem that warpage occurs.
Therefore, a wood fiberboard having a small dimensional change rate due to moisture is required. In order to improve the bending strength of the above-mentioned wood fiber board, the one in which the front and back surfaces are impregnated with a thermosetting resin is hardened with respect to impact resistance, that is, consideration is given to chipping due to impact force. Even if a decorative board is manufactured using a wood base material having a wood fiber board that has been subjected to this type of surface treatment as a surface layer, the wood fiber board is partially affected by the impact force received on the production line. There may be cases where chipping occurs. In addition, a special heating and pressing process for curing the resin impregnated by coating is required, which increases the number of working processes and leads to a cost increase.

Therefore, an object of the present invention is to provide a manufacturing method capable of easily manufacturing a wood fiberboard which has high impact resistance and does not cause chipping or delamination even when an impact force is applied. It is in. Another object of the present invention is to provide a manufacturing method capable of easily manufacturing a wood fiber board which hardly causes warpage even when it is laminated with plywood to form a composite board.

[0008]

According to the present invention, the above-mentioned problems can be solved in a conventionally known method for producing a wood fiber board,
Immediately after the step of heating and pressing a fiber mat in which defibrated plant fibers are temporarily molded with an adhesive (usually a formalin-based adhesive is used), a polymer other than formalin-based polymer is applied to the surface of the fiberboard in the high temperature state. This can be achieved by coating and impregnating a compound, curing the impregnated polymer compound by residual heat of the fiber board, and drying to form a hard resin-impregnated layer on at least the surface layer. In the present invention, "high temperature state"
The term "state" means a temperature range in which the polymer material coated and impregnated on the surface of the fiber board can easily penetrate into at least the surface layer of the fiber board and be cured.

The wood fiberboard referred to in the present invention includes all wood fiberboards such as conventionally known MDF and HB (hard board). In particular, the method of the present invention is effective for MDF, and the MDF may be any of U type, M type, and P type referred to in JIS A5905, and has a specific gravity of 0.35 g / cm ^{3 to} 0.80 g / cm ^3. It is of a degree.

The polymer compound other than the formalin-based resin applied to the surface of the wood fiberboard has a resin-impregnated layer having a high hardness on the surface layer of the wood fiberboard, that is, peeling between the fibers is less likely to occur, thereby making the fiberboard. Any polymer compound having a property of forming an impregnated layer that hardly causes chipping in the layer may be used, and may be a thermosetting type or a moisture curing type. Preferably, unsaturated polyester, acrylic urethane, moisture-curable urethane, silicone resin, epoxy resin, or the like is used. In the case of a moisture-curable type, those resins to which a curing accelerator such as ketimine is added may be used. These resins undergo three-dimensional cross-linking upon curing. As a result, the wood fibers, which are the materials of the wood fiber board, are strongly tightened, and the impact resistance and peel strength of the wood fiber board are improved. Also, an emulsion having a relatively low Tg can be used. As a low Tg emulsion, acrylic emulsion, SRB
Examples thereof include latex and EVA emulsion.

The polymer compound is applied by a flow coater,
The coating may be performed by a conventionally known coating device such as a roll coater or a spreader. The application amount is such that the applied polymer compound is impregnated from the surface of the wood fiber board by about 0.3 mm to 3 mm. Preferably, 3 g / scale ² ~
It is about 30 g / scale ² , and if it is less than that, the effect of preventing chipping and the like is poor, and if it is more than that, cost increases and workability deteriorates.

In the present invention, the polymer compound is in a high temperature state after heating and pressing, that is, the polymer material coated and impregnated on the surface of the fiber board easily permeates at least the surface layer and is cured. It is applied to a fiberboard in a temperature range where it is possible, and left as it is until it reaches room temperature while blowing air with a blower if necessary, as in the case of manufacturing a normal wood fiberboard. Thereby, the polymer compound easily permeates and impregnates the inside of the fiberboard, and the impregnated polymer compound is cured and dried by the residual heat of the fiberboard. Therefore, the present invention does not require a special process or apparatus for drying and curing the polymer compound such as ultraviolet irradiation or drying (hot air drying).

According to the present invention, a resin impregnated layer as a reinforcing layer is formed by coating and impregnating at least the surface layer of a wood fiber board with a polymer compound other than a formalin-based resin and curing it. As a result, the impact resistance and peeling resistance of the wood fiberboard are improved, the chipping of the wood fiberboard that has conventionally occurred when pasting the surface decorative material, etc. is avoided, and the impact force from the outside is applied to the surface of the wood laminate. It is also avoided that peeling occurs from the part when the is added. In addition, it is possible to suppress a dimensional change due to the original water content of the wood fiber board, and to suppress the occurrence of warpage when the wood fiber board is attached to plywood.

In the case of producing a decorative board using the wood fiberboard produced by the production method of the present invention as a base material, it is laminated with plywood or the like, if necessary, and then the surface thereof is the same as a conventional wood base material. Sanding, then apply an adhesive to the surface of the polymer compound-impregnated layer and bond the surface decorative material, or directly bond the surface decorative material having the adhesive layer formed on the back surface, and after bonding, For example, they may be integrated by thermocompression bonding using a thermocompression press.

[0015]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples. [Example 1] Urea melamine co-condensation resin was used as an adhesive for the fibers disentangled by a defibrillator, and after forming into a mat by a forming machine, temporary compression was performed. It was heated and pressed by a hot press to obtain a 3 mm thick MDF. After depressurization, immediately on the surface of the MDF is coated impregnated polyester type moisture-curable urethane resin in 10 g / scale ^2, left to cool at room temperature to cure the impregnated resin. The urethane resin was impregnated with about 1 mm from the surface of the MDF. This MDF and a softwood plywood having a thickness of 9 mm were adhered to each other to prepare an MDF composite board. SBR + urea melamine resin adhesive is applied to the surface of MDF at 9 g / scale ² and the thickness is 0.3 mm.
The oak veneer plate was attached and pressed at 120 ° C. and 7 kg / cm ² for 60 seconds. Amino alkyd paint was applied to the surface of the veneer-bonded composite board at 7 g / square ² to produce an MDF composite decorative board.

[Embodiment 2] A thickness of 3 is obtained in the same manner as in Embodiment 1.
mm of MDF was obtained. Immediately after releasing the pressure, a polyester type moisture-curable urethane resin is applied to the surface of the MDF 15
It was coated and impregnated with g / measure ² , and allowed to cool at room temperature to cure the impregnated resin. The urethane resin was impregnated with about 1.2 mm from the surface of the MDF. This MDF and thickness 9mm
The softwood plywood of No. 1 was glued to make an MDF composite board. MDF
After polishing the surface with a sander, SBR + urea melamine resin adhesive was applied to the surface of MDF at 9 g / square ² to a thickness of 0.
A 3 mm oak veneer was attached and pressed at 120 ° C. and 7 kg / cm ² for 60 seconds. Amino alkyd paint was applied to the surface of the veneer-bonded composite board at 7 g / square ² to produce an MDF composite decorative board.

[Third Embodiment] The thickness of the third embodiment is the same as that of the first embodiment.
mm of MDF was obtained. Immediately after releasing the pressure, 15 g of a self-crosslinking type acrylic resin emulsion is applied to the surface of the MDF.
The coating resin was impregnated with a scale of ² and allowed to cool at room temperature to cure the impregnated resin. The acrylic resin was impregnated with about 0.8 mm from the MDF surface. This MDF and a softwood plywood having a thickness of 9 mm were adhered to each other to prepare an MDF composite board. After polishing the MDF surface with a sander, apply SBR + urea melamine resin adhesive at 9 g / scale ² to the MDF surface to a thickness of 0.3.
6 mm at 120 ° C and 7 kg / cm ²
Press for 0 seconds. Amino alkyd paint was applied to the surface of the veneer-bonded composite board at 7 g / square ² to produce an MDF composite decorative board.

[Embodiment 4] A thickness of 3 is obtained in the same manner as in Embodiment 1.
mm of MDF was obtained. After depressurization, immediately self-crosslinking type SBR latex was applied impregnated with 15 g / scale ² on the surface of the MDF, left to cool at room temperature to cure the impregnated resin. SBR latex is about 0.
It was impregnated with 7 mm. This MDF and a softwood plywood having a thickness of 9 mm were adhered to each other to prepare an MDF composite board. After polishing the MDF surface with a sander, apply SBR + urea melamine resin adhesive at 9 g / scale ² on the MDF surface to a thickness of 0.3 mm.
The oak veneer plate was attached and pressed at 120 ° C. and 7 kg / cm ² for 60 seconds. Amino alkyd paint was applied to the surface of the veneer-bonded composite board at 7 g / square ² to produce an MDF composite decorative board.

[Embodiment 5] Same as Embodiment 1, 3 mm
Was obtained. Immediately after decompressing, 25 g / minute of polyester-type moisture-curing urethane resin on both sides of the MDF
A scale ² was used for coating and impregnation, and the mixture was allowed to stand at room temperature and cooled to cure the impregnated resin. The urethane resin was impregnated in all layers of MDF. After polishing both sides of MDF with sander, this M
DF and a 9 mm thick softwood plywood were adhered to make an MDF composite board. An SBR + urea melamine resin adhesive was applied to the surface of the MDF at 9 g / square ² and a oak veneer having a thickness of 0.3 mm was attached, and pressed at 120 ° C. and 7 kg / cm ² for 60 seconds. Amino alkyd paint was applied to the surface of the veneer-bonded composite board at 7 g / square ² to produce an MDF composite decorative board.

[Comparative Example 1] A MDF having a thickness of 3 mm and a softwood having a thickness of 9 mm produced in the same manner as in Example 1 except that a polyester type moisture-curing urethane resin was not applied to the surface after decompression. Create an MDF composite board with plywood bonded, apply SBR + urea melamine resin adhesive at 10 g / scale ² on the surface of the MDF and stick a oak veneer with a thickness of 0.3 mm at 120 ° C, 7 kg / cm ² 60 Pressed for seconds. Amino alkyd paint was applied to the surface of the veneer-bonded composite board at 7 g / square ² to produce an MDF composite decorative board.

Comparative Example 2 Both sides of a 3 mm thick MDF manufactured in the same manner as in Example 1 were sanded with a sander except that the surface was not coated with a polyester type moisture-curing urethane resin after depressurization. The MDF to a thickness of 6 m
m of the softwood plywood was attached to the front and back surfaces to prepare an MDF composite board. SBR + urea melamine resin adhesive was applied to the surface at 10 g / scale ² and a oak veneer having a thickness of 0.3 mm was attached, and pressed at 120 ° C. and 7 kg / cm ² for 60 seconds. Amino alkyd paint was applied to the surface of the veneer-bonded composite board at 7 g / square ² to produce an MDF composite decorative board.

A caster test, a plane tensile test, and a warp amount were measured for each of them. The results are shown in Table 1. The caster test is 2
After applying a load of 5 kg and reciprocating the test piece 3000 times at a distance of 100 mm in that state, visually observing the presence or absence of peeling of the decorative veneer and the coating film, etc., using a dial gauge, The maximum dent is measured to 1/100 mm, and at this time, the test piece makes one revolution in about 17 reciprocations and returns to the original position.

The plane tensile test conforms to JAS (special plywood), and one side is 20 m on the surface of the test piece.
A metal plate having a square m-shaped bonding surface was bonded using a cyanoacrylate-based adhesive, and a cut having a depth reaching a wood fiberboard such as MDF was attached to the periphery, and then a plane tensile test was performed. The amount of warpage is measured by attaching a weight to the other end of a thread having one end fixed to one end in the length direction of a 1 × 6 length test piece and dropping the weight from the other end side of the test piece to remove the thread. The tension was set to a tight state, and the maximum distance (maximum arrow height) (mm) between the surface of the test piece and the thread at that time was measured as the warp amount.

[0024]

[Table 1]

As can be seen from Table 1, the decorative sheets of the examples are clearly improved in dents and peeling of MDF by the caster test as compared with the comparative examples. This allows
When the wood fiberboard manufactured by the manufacturing method according to the present invention is used as a base material, the base material M is used in the manufacturing process of the decorative board.
It can be seen that chipping of the DF can be avoided, and peeling does not occur in the obtained product. further,
It can be seen that the warpage amount in the example is extremely small, and the dimensional change due to the original water content of MDF when laminated with plywood is reduced.

[0026]

EFFECT OF THE INVENTION According to the production method of the present invention, a polymer compound other than a formalin-based compound applied for the purpose of improving the surface height of a wood fiberboard is provided without providing a special step for drying and curing. It can be dried and cured in the process of natural cooling after heating and pressing. Therefore, it is possible to manufacture a wood fiberboard having a resin-impregnated layer in which at least the surface layer portion is reinforced, using the conventional manufacturing apparatus as it is and in substantially the same manufacturing time, which leads to cost reduction.

Further, in the decorative board using the wood fiberboard manufactured by the manufacturing method of the present invention as a base material, it is necessary to avoid chipping of the wood fiberboard during the manufacturing process in manufacturing the decorative board. The quality of the decorative plate is improved.
It is also possible to avoid delamination of the fiberboard when an external impact is applied to the decorative board.

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B27N 7/00 B27N 3/04

Claims (2)

(57) [Claims] 1. In the method for producing a wood fiberboard, after the step of heat-pressing a fiber mat in which defibrated plant fibers are temporarily molded with an adhesive, the surface of the fiberboard in the high temperature state is treated with a material other than formalin-based resin. A method for producing a wood fiber board, which comprises coating and impregnating a molecular compound, and curing and drying the impregnated polymer compound by residual heat of the fiber board to form a resin-impregnated layer at least in a surface layer portion. 2. In the method for producing a wood fiberboard, after the step of heating and pressing a fiber mat obtained by temporarily forming defibrated plant fibers with a formalin-based adhesive, the surface of the fiberboard in a high temperature state other than formalin-based The method for producing a wood fiber board, characterized in that a resin-impregnated layer is formed at least on the surface layer part by coating and impregnating the polymer compound of 1. with the impregnated polymer compound and curing and drying with residual heat of the fiber board. Method.