JP7417419B2 - wood fiber board - Google Patents

Description

The present invention relates to a wood fiber board formed from fibers made from defibrated wood chips made from softwood, and a method for manufacturing the same.

Traditionally, wood fiber boards are manufactured by hot-pressing flakes, chips, fibers, and the like. For example, Patent Document 1 discloses that after heating wood chips made from coniferous trees in an atmosphere containing moisture, the heated wood chips are defibrated into fibers, and the defibrated fibers are pressurized and heated. The wood fiber board is formed using Here, as an example of the heating conditions for the wood shavings before being defibrated into fibers, the wood shavings are heated under saturated steam pressure for 5 minutes at 0.8 MPa (specifically, the heating temperature is 170°C). are doing.

Japanese Patent Application Publication No. 2012-214011

However, when a wood fiber board is manufactured using the manufacturing method shown in Patent Document 1, when comparing the color of the raw material wood shavings (softwood) and the color of the wood fiber board, it is found that the color of the wood shavings before defibration differs from that of the wood fiber board. In contrast, the inventors noticed that the color of the wood fiber board was darkening.

The present invention has been made in view of these points, and its purpose is to provide a wood fiber board with a whitish color similar to the color of wood chips before defibration, and a manufacturing method for manufacturing the same. Our goal is to provide the following.

After extensive research, the inventors determined that the darkening of the color of wood fiber boards is due to discoloration of the surface of the single fibers due to processing heat during processing into single fibers during the fibrillation process. Ta. In particular, it has been found that the fibers may continue to be heated as they move between the teeth of the refiner in a single fiber state. Therefore, if a fiber aggregate made up of single fibers is left behind while the single fibers move between the teeth of the refiner immediately after being processed into single fibers, the heat of the single fibers that would normally be heated can be transferred to the fiber aggregate. We thought that it would be possible to absorb heat and suppress discoloration of single fibers.

The present invention is based on the new findings of the inventors, and the method for manufacturing a wood fiber board according to the present invention involves heating wood shavings made from coniferous trees in an atmosphere containing moisture, and then heating them. A method for manufacturing a wood fiber board, comprising: a defibration step of defibrating wood chips into fibers; and a molding step of molding a wood fiber board by pressurizing and heating the defibrated fibers, the method comprising: In the defibration step, single fibers and fiber aggregates in a state before being defibrated into single fibers are produced as the fibers from the wood chips, and in the defibration step, the opening The method is characterized in that the wood shavings are defibrated so that the fiber aggregates that do not pass through a sieve with a diameter of 150 μm are in the range of 40% to 52% by mass based on the defibrated fibers.

According to the present invention, what does not pass through a sieve with an opening of 150 μm is a fiber aggregate made up of single fibers, and this fiber aggregate accounts for 40% to 52% by mass of the defibrated fibers. The wood shavings are defibrated to a range of .

As a result, even if single fibers and fiber aggregates are heated by processing heat immediately after being processed into single fibers and fiber aggregates in the fibrillation process, the heat capacity of the fiber aggregates is larger than that of single fibers, so Processing heat is absorbed by the fiber aggregate. Thereby, discoloration of single fibers can be suppressed. The color of the fibers made from defibrated wood chips is close to the color of the wood chips before heating, so the color of the wood fiber board formed from these fibers is also close to the color of the wood chips before heating. As a result, a wood fiber board having a color unique to wood can be manufactured.

In particular, coniferous trees are whitish compared to hardwoods, so if wood shavings made from coniferous trees are used as in the present invention, a wood fiber board with a whitish appearance can be obtained. As a result, even if a white veneer, for example, is bonded to the wood fiber board, dark spots on the surface of the wood fiber board can be prevented from being reflected on the surface of the veneer.

In the defibration process, if the wood shavings are defibrated so that the fiber aggregates that do not pass through a sieve with an opening of 150 μm are less than 40% by mass of the total defibrated fibers, the amount of single fibers is Since the amount of fiber aggregates is small, processing heat is easily input to the single fibers. As a result, discoloration of single fibers cannot be sufficiently suppressed.

On the other hand, in the defibration process, if the wood shavings are defibrated so that the fiber aggregate that does not pass through a sieve with an opening of 150 μm exceeds 52% by mass of the total defibrated fibers, the fiber aggregate Because the proportion is high, the dimensional change of a wood fiber board formed from this fiber may become large under humidified and water-absorbed environments.

Furthermore, the inventors thought that the darkening of the manufactured wood fiber board was due to the hemicellulose contained in the wood chips being discolored by the heat when the wood chips were heated before defibration. This discoloration depends on the heat energy applied to the wood shavings, so new findings show that it is important to suppress the heat energy applied to the wood shavings to the extent that the wood shavings can be defibrated. , the inventors obtained.

More preferably, in the defibration step, the heating temperature for heating the wood chips is in the range of 155°C to 170°C, and the heating time for heating the wood chips is in the range of 3 to 6 minutes. In the graph of the heating temperature and the heating time, there is a first point where the heating temperature is 170°C and a heating time of 3 minutes, a second point where the heating temperature is 155°C and a heating time of 3 minutes, and The wood shavings are heated at a heating temperature and heating time within a region surrounded by a line segment connecting the third point at a temperature of 155° C. and a heating time of 6 minutes.

According to the present invention, in the defibration step, the wood chips are heated at a heating temperature and heating time within the region connecting the first to third points, so that the wood chips turn black due to heat. You can suppress things. As a result, the color of the fibers obtained by defibrating the wood chips is close to the color of the wood chips before heating, and the color of the wood fiber board formed from these fibers is also close to the color of the wood chips before heating. As a result, a white wood fiber board, which is a color unique to wood, can be manufactured.

Here, if the heating temperature is less than 155° C., the fibers of the wood chips that are defibrated tend to become fine (pulverized), which may reduce the strength of the wood fiber board. On the other hand, if the heating time exceeds 170°C, the wood shavings tend to turn black due to the heat, and even if a wood fiber board is formed from fibers made by defibrating the wood shavings, the wood fiber board will turn black. Sometimes it happens.

Furthermore, if the heating time is less than 3 minutes, the fibers of the wood chips that are defibrated tend to become fine (pulverized), which may reduce the strength of the wood fiber board. On the other hand, if the heating time exceeds 6 minutes, the wood shavings tend to turn black due to the heat, and even if a wood fiber board is formed from fibers made from defibrated wood shavings, the wood fiber board will turn black. Sometimes it happens.

Furthermore, even if the heating temperature for heating the wood shavings is in the range of 155°C to 170°C and the heating time for heating the wood shavings is in the range of 3 minutes to 6 minutes, it is outside the range defined by the present invention. In this case, there is a lot of heat input into the wood chips, which tends to cause them to turn black. Therefore, even if a wood fiber board is formed from fibers made from defibrated wood chips, the wood fiber board may turn dark.

A wood fiber board is also disclosed herein as the present invention. The wood fiber board according to the present invention is a wood fiber board formed from fibers obtained by defibrating wood chips made from coniferous trees, and the fibers include single fibers and the fibers before being defibrated into the single fibers. and a fiber aggregate in a state of When the color difference calculated from L ^* , a ^* , and b ^* specified in JIS Z 8781-4 is △E, the color difference between the color of the wood fiber board and the color of the coniferous wood of the raw material It is characterized in that ΔE is 5.1 or less.

According to the present invention, a wood fiber board in which the fiber aggregate that does not pass through a sieve with an opening of 150 μm is in the range of 40% to 52% by mass based on the defibrated fibers, It can be said that discoloration, which would sometimes cause the fibers to darken, is suppressed. This type of wood fiber board is a wood fiber board with a whitish color, which is a color unique to softwood, because the color difference ΔE between the color of the wood fiber board and the color of the raw material softwood is 5.1 or less. .

In a more preferred embodiment, the surface of the wood fiber board is provided with a decorative material having L ^* higher than L ^* of the surface of the wood fiber board. According to this aspect, even when a decorative material with high L ^* (brightness) is provided on the exposed surface of the single fibers and fiber aggregates of the wood fiber board, the surface of the wood fiber board of the decorative material is reflected. You can prevent it from getting too crowded.

According to the present invention, it is possible to obtain a wood fiber board that has a whitish color similar to that of coniferous wood chips before defibration.

FIG. 1 is a flow diagram for explaining a method for manufacturing a wood fiber board according to an embodiment of the present invention. FIG. 2 is a schematic diagram of a refiner used in the defibration step shown in FIG. 1. FIG. 3 is a schematic diagram of fibers defibrated by the refiner shown in FIG. 2. FIG. 2 is a graph showing the relationship between heating temperature and heating time of wood chips in the defibration process shown in FIG. 1. FIG. FIG. 2 is a schematic cross-sectional view showing a state in which a decorative material is adhered to the surface of a wood fiber board manufactured by the manufacturing method shown in FIG. 1. FIG.

Embodiments according to the present invention will be described below.
The method for manufacturing a wood fiber board according to the present embodiment is a method of defibrating wood chips into wood fibers and manufacturing a wood fiber board from the defibrated wood fibers. This is a method of manufacturing wood fiber board.

First, a wood fiber board according to this embodiment will be described with reference to FIGS. 1 and 2, and a manufacturing method thereof will be described.

The method for manufacturing the wood fiber board 1 in this embodiment includes at least a defibration step S11, an accumulation step S12, and a molding step S13 shown below. Each step will be explained below.

Regarding the defibration step S11 The defibration step S11 will be described below with reference to FIGS. 1 to 3. First, chip-shaped wood shavings are prepared as a starting material for the wood fiber board 1 of the embodiment. As the wood chips, for example, wood chips T made from coniferous trees such as cedar, pine, and cypress are prepared.

Next, such wood chips T are heated in an atmosphere containing moisture, and then the heated wood chips T are defibrated into wet fibers F. Specifically, wood chips T are put into the pressure vessel 33 via the material supply section 32, and steam s is supplied to the pressure vessel 33 via the steam supply section 31.

Next, the steamed wood chips T are fed into the blade mold 35 from the discharge part 34 of the pressure vessel 33. Specifically, although not shown, a heated wood chip T (specifically, a state where the temperature is maintained) is supplied into the blade mold 35, and this wood chip T is fed into the blade mold 35. It is sent between 35 and 36. The output shaft of a motor 37 is connected to the blade die 36 .

As a result, the blade die 36 rotates, the wood chips T are defibrated between the blade types 35 and 36, and the fibers F consisting of the single fiber fa and the fiber aggregate fb are distributed from the center of rotation toward the outer periphery. released. In this embodiment, by making the interval d between the blades 35 and 36 wider than before, the fiber aggregate fb that does not pass through a sieve with an opening of 150 μm in the defibrating step S11 is reduced to the entire defibrated fiber F. The wood shavings T are defibrated so that the content is in the range of 40% by mass to 52% by mass.

Here, the opening is the nominal opening defined in JIS Z 8801-1 (2019), and by classifying the defibrated fibers after the defibration process described below, the opening is 150 μm. The percentage of the fiber aggregate fb that does not pass through the sieve can be confirmed.

The fibers that do not pass through the sieve with an opening of 150 μm are the fiber aggregate fb, which is a collection of single fibers fa, and the fibers that pass through the sieve are the single fibers fa. By defibrating the wood chips T so that the fiber aggregate fb is in the range of 40% to 52% by mass based on the defibrated fiber F, the single fiber fa and the fiber aggregate fb are Even if the single fiber fa and the fiber aggregate fb are heated by processing heat immediately after being processed, the heat of the single fiber fa is absorbed by the fiber aggregate fb. Thereby, discoloration of the single fiber fa can be suppressed.

In the defibrating step S11, when the wood chips T are defibrated so that the fiber aggregates fb that do not pass through a sieve with an opening of 150 μm are less than 40% by mass of the entire defibrated fibers F, Since the amount of fiber fa is large, processing heat is easily input into the single fiber fa. As a result, discoloration of the single fiber fa cannot be sufficiently suppressed.

On the other hand, in the defibrating step S11, when the wood chips T are defibrated so that the fiber aggregate fb that does not pass through a sieve with an opening of 150 μm exceeds 52% by mass of the entire defibrated fibers F, Since the amount of single fibers fa decreases, the strength of the wood fiber board 1 formed from the fibers F may decrease.

In the defibration step S11, the heating temperature for heating the wood chips T in the pressure vessel 33 is preferably in the range of 155°C to 170°C, and the heating time for heating the wood chips is 3 minutes to 6 minutes. Preferably, the range is within the range. In particular, as shown in FIG. 4, in the graph of heating temperature and heating time, there is a first point P1 where the heating temperature is 170°C and a heating time of 3 minutes, and a second point where the heating temperature is 155°C and a heating time of 3 minutes. The wood shavings T are heated at the heating temperature and heating time within the area S surrounded by the line segment connecting the point P2 of No. 2 and the third point P3, which has a heating temperature of 155° C. and a heating time of 6 minutes. It is preferable to do so.

As is clear from experiments conducted by the inventors to be described later, in the defibration step S11, the wood shavings T are heated at the heating temperature and heating time within the region S connecting the first to third points P1 to P3. By doing so, it is possible to suppress the wood chips T from turning black due to heat. As a result, the color of the fibers obtained by defibrating the wood chips T becomes close to the color of the wood chips T before heating.

Here, if the heating temperature is less than 155° C., the fibers F of the wood chips T that are defibrated tend to become fine (pulverized), which may reduce the strength of the wood fiber board. On the other hand, if the heating temperature exceeds 170°C, the wood chips T tend to discolor to black due to the heat, and even if a wood fiber board is formed from the fibers F obtained by defibrating the wood chips T, the wood fibers The board may turn black.

Furthermore, if the heating time is less than 3 minutes, the fibers of the wood chips T that are defibrated tend to become fine (pulverized), which may reduce the strength of the wood fiber board 1. On the other hand, if the heating time exceeds 6 minutes, the wood shavings T tend to discolor to black due to the heat, and even if the wood fiber board 1 is formed from the fibers obtained by defibrating the wood shavings T, the wood fibers Board 1 may turn black.

Furthermore, even if the heating temperature for heating the wood shavings is in the range of 155°C to 170°C and the heating time for heating the wood shavings is in the range of 3 minutes to 6 minutes, it is outside the range defined by the present invention. In this case, a large amount of heat is input to the wood shavings T, and this heat tends to cause the wood shavings T to discolor to black. Therefore, even if the wood fiber board 1 is formed from the fibers obtained by defibrating the wood chips T, the wood fiber board 1 may become darkened.

About accumulation step S12 In this step, an adhesive is added to the defibrated fibers F, and then dried, and accumulated into a mat shape (forming a wood mat). The adhesive may be either an adhesive made of a thermosetting resin or an adhesive made of a thermoplastic resin. The thermosetting resin may be a room temperature curing type or a thermosetting type thermosetting resin, such as urea resin, melamine resin, phenol resin, epoxy resin, unsaturated polyester resin, polyurethane resin, diallyl phthalate resin, silicone resin. , or alkyd resins.

Regarding the molding step S13 In this step, the molded wood mat is put into a press and pressurized and heated (thermal pressure) to mold the wood fiber board. Specifically, a wood mat is placed in a molding device and hot-pressed at a heating temperature of 160° C. to 260° C., a pressurizing condition of 0.2 MPa to 5 MPa, and a pressure holding time of 30 seconds to 5 minutes.

Regarding the wood fiber board 1 The wood fiber board 1 thus obtained is a wood fiber board 1 formed from fibers F obtained by defibrating wood chips T made from coniferous trees. As shown in FIG. 5, the fiber F includes a single fiber fa and a fiber aggregate fb in a state before being defibrated into single fibers fa. The wood fiber board 1 contains fiber aggregates fb that do not pass through a sieve with an opening of 150 μm in a range of 40% by mass to 52% by mass based on the defibrated fibers F.

According to the present invention, the wood fiber board in which the fiber aggregates fb that do not pass through a sieve with an opening of 150 μm is in the range of 40% by mass to 52% by mass based on the defibrated fibers F, as described above, Discoloration such as darkening of the fiber F during defibration is suppressed.

Therefore, since the color of the fiber F obtained by defibrating the wood chips T is close to the color of the wood chips T before heating, the color of the wood fiber board 1 formed from this fiber also differs from that of the wood chips T before heating. Close to color. As a result, a wood fiber board 1 having a color unique to wood can be manufactured.

Specifically, when the color difference calculated from L ^* , a ^* , and b ^* specified in JIS Z 8781-4 (2013) (CIE1976 color system) is △E, the softwood before defibration The color difference ΔE between the color of the wood fiber board 1 and the color of is 5.1 or less. Therefore, the wood fiber board 1 has a color difference ΔE of 5.1 or less. In particular, coniferous trees are whitish compared to hardwoods, so if wood shavings T made from coniferous trees are used as in this embodiment, it is possible to obtain a whitish wood fiber board 1. .

As shown in FIG. 5, a decorative material 50 may be attached to the surface of the wood fiber board 1 with an adhesive. Examples of adhesives used here include solution-based adhesives (including organic solvent-based adhesives) such as vinyl acetate resin emulsion adhesives, urea resin adhesives, epoxy resin adhesives, phenolic resin adhesives, and synthetic rubber adhesives, or water-based adhesives. Examples include dispersion adhesives. An adhesive may be used instead of the adhesive, and examples of the adhesive include acrylic resin adhesive, synthetic rubber adhesive, natural rubber adhesive, vinyl ether adhesive, silicone adhesive, and urethane adhesive. Adhesives such as adhesives can be mentioned.

It is preferable that the decorative material 50 has L ^* (lightness) lower than the L ^* (lightness) of the surface of the wood fiber board 1. Normally, the decorative material 50 having a high L ^* (lightness) is whitish, so the dark color of the surface of the wood fiber board is likely to be reflected therein. However, in this embodiment, even when the decorative material 50 with high L ^* (lightness) is provided on the exposed surface, it is possible to suppress the reflection of the surface of the decorative wood fiber board.

Examples of the decorative material 50 include the above-mentioned coniferous veneer or craft paper, and in the case of veneer, the surface of the wood fiber board 1 serving as the base is likely to be reflected, and the thickness is about 0.2 to 0.6 mm. It is preferable that the veneer has a thickness of .

Examples of the present invention will be described below.

[Example 1]
As wood chips, coniferous wood chips (cedar) several centimeters in size were steamed at a heating temperature (steaming temperature) of 160°C for a heating time (steaming time) of 3 minutes using the refiner shown in Figure 2. While the heating temperature of the softwood chips was maintained, the softwood chips were defibrated using a refiner. The spacing between the blades was set to twice the conventional spacing. Measure the weight of the defibrated fibers, classify them using a sieve with an opening of 150 μm in accordance with JIS Z 8801-1 (2019), and measure the total mass of fiber aggregates that do not pass through the sieve with an opening of 150 μm. The percentage was measured. The results are shown in Table 1.

[Example 2]
In the same manner as in Example 1, softwood chips were defibrated using a refiner. The difference from Example 1 is that the spacing between the blade shapes was adjusted so that the proportion of fiber aggregates was higher than in Example 1. Then, in the same manner as in Example 1, the total mass of the fiber aggregates that did not pass through the sieve having an opening of 150 μm was measured, and the proportion thereof was determined. The results are shown in Table 1.

[Example 3 and 4]
In the same manner as in Example 1, softwood chips were defibrated using a refiner. Example 3 differs from Example 1 in that the steaming temperature was set at 165°C. Example 4 differs from Example 1 in that the steaming temperature was set to 165° C. and that the fibers were defibrated at the spacing between the blades of Example 2. Then, in the same manner as in Example 1, the total mass of the fiber aggregates that did not pass through the sieve having an opening of 150 μm was measured, and the proportion thereof was determined. The results are shown in Table 1.

[Comparative example 1]
In the same manner as in Example 1, softwood chips were defibrated using a refiner. The difference from Example 1 is that, with respect to Example 1, under the conditions shown in Patent Document 1, the spacing between the blades was narrowed so that the proportion of fiber aggregates was reduced, and the steaming temperature and steaming time were changed. adjusted. Then, in the same manner as in Example 1, the total mass of the fiber aggregates that did not pass through the sieve having an opening of 150 μm was measured, and the proportion thereof was determined. The results are shown in Table 1.

[Comparative example 2]
In the same manner as in Example 3, the softwood chips were defibrated using a refiner. The difference from Example 3 is that, with respect to Example 3, the spacing between the blade dies was narrowed to the conventional spacing under the conditions shown in Patent Document 1. Then, in the same manner as in Example 3, the total mass of the fiber aggregates that did not pass through the sieve having an opening of 150 μm was measured, and the proportion thereof was determined. The results are shown in Table 1.

(Evaluation test)
The fibers obtained in Examples 1 to 4 and Comparative Example 1 were molded into wood mats using a mat molding machine. This wood mat was put into a press and pressed under heating conditions, namely, a heat-pressing temperature of 185° C. and a heat-pressing time of 50 seconds, to obtain a wood fiber board to a thickness of 3 mm. In addition, Comparative Example 1 is in a state close to that of commercially available wood fiber boards.

L ^* , a ^* , and b ^* specified in JIS Z 8781-4 (2013) were measured on the surface of the obtained wood fiber board using a spectrocolorimeter (Nippon Denshoku, SE7700). . Furthermore, wood shavings (sapwood + heartwood) were crushed in the same composition as the raw material for the wood fiber board so as not to discolor, and L ^* , a ^* , and b ^* of this powder were measured. The color difference ΔE between the color of the wood fiber board and the color of the softwood (cedar) before defibration was calculated using the following equation 1. In addition, in Equation 1 below, L ^* , a ^* , and b ^* of the cedar powder serving as a reference are L0, _a0 , and _b0 , and L ^* , ^a* _, and b ^* of the wood fiber board. are L ₁ , a ₁ , and b ₁ . The results are shown in Table 1.

In the wood fiber boards of Examples 1 to 4, the color difference of the wood fiber boards was Δ5.1 or less, which was close to the color inherent to softwood chips (cedar). On the other hand, in the wood fiber boards of Comparative Examples 1 and 2, the color difference of the wood fiber boards exceeded 7.0, and it was confirmed that the color was darker than the color inherent to softwood chips (cedar).

Examples 1 to 4 have a higher proportion of fiber aggregates than Comparative Examples 1 and 2. From this, even if single fibers and fiber aggregates are heated by processing heat immediately after being processed into single fibers and fiber aggregates, in Examples 1 to 4, single fibers and fiber aggregates are It is thought that discoloration of the single fibers could be suppressed because heat was absorbed. As a result, it is considered that in Examples 1 to 4, wood fiber boards with a whitish color similar to wood chips made from coniferous trees could be obtained.

[Example 5]
In the same manner as in Example 1, softwood chips were defibrated using a refiner. The difference from Example 1 is that, with respect to Example 1, the heating temperature was 170° C. and the heating time was 3 minutes, which corresponds to the first point P1 in the graph of FIG.

[Example 6]
In the same manner as in Example 1, softwood chips were defibrated using a refiner. The difference from Example 1 is that, with respect to Example 1, the heating temperature was 155° C. and the heating time was 3 minutes, which corresponds to the first point P2 in the graph of FIG.

[Example 7]
In the same manner as in Example 1, softwood chips were defibrated using a refiner. The difference from Example 1 is that, with respect to Example 1, the heating temperature was 155° C. and the heating time was 6 minutes, which corresponds to the first point P3 in the graph of FIG.

[Comparative example 3]
In the same manner as in Example 1, softwood chips were defibrated using a refiner. The difference from Example 1 is that the heating temperature was 160° C. and the heating time was 7 minutes.

[Comparative example 4]
In the same manner as in Example 1, softwood chips were defibrated using a refiner. The difference from Example 1 is that the heating temperature was 165° C. and the heating time was 7 minutes.

(Evaluation test)
In the same manner as in Example 1, a wood mat was formed from the fibers obtained in Examples 5 to 7 and Comparative Examples 3 and 4 using a mat forming machine, and this wood mat was put into a press machine. Manufactured wood fiber board. Similarly to Example 1, L ^* , a ^* , and b ^* were measured on the surface of the obtained wood fiber board, and the color difference between the color of the wood fiber board and the color of the softwood (cedar) before defibration was determined. ΔE was calculated.

In the wood fiber boards according to Examples 5 to 7, the color difference of the wood fiber boards was about 4, which was close to the color specific to softwood chips (cedar). On the other hand, in the wood fiber boards of Comparative Examples 3 and 4, the color difference of the wood fiber boards was about 6, and it was confirmed that the color was darker than the color specific to softwood chips (cedar).

In Examples 4 to 6, less heat was input in the defibration step than in Comparative Examples 3 and 4, as is clear from the heating temperature and heating time at which the wood chips were heated. From this, it is assumed that within the region S of the graph shown in FIG. 4, it is possible to obtain a wood fiber board with a whitish color similar to that of wood chips made from coniferous trees.

Although one embodiment of the present invention has been described in detail above, the present invention is not limited to the above-described embodiment, and various modifications may be made without departing from the spirit of the present invention as set forth in the claims. The design can be changed.

1: wood fiber board, S11: fibrillation process, S13: molding process, F: fiber, fa: single fiber, fb: fiber aggregate, T: wood shavings, P1: first point, P2: second point Point, P3: third point

Claims (2)

A wood fiber board formed from fibers made from defibrated wood chips made from coniferous trees,
The fiber includes a single fiber and a fiber aggregate in a state before being defibrated into the single fiber,
The wood fiber board contains a fiber aggregate that does not pass through a sieve with an opening of 150 μm in a range of 40% to 52% by mass based on the defibrated fibers,
When the color difference calculated from L ^* , a ^* , and b ^* specified in JIS Z 8781-4 is ΔE, the color difference ΔE between the color of the wood fiber board and the color of the coniferous wood used as the raw material is 5. 1 or less. The wood fiber board according to claim 1 , wherein a decorative material having L ^* higher than L ^* of the surface of the wood fiber board is provided on the surface of the wood fiber board.

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