JP3337519B2 - High strength particle board and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-strength particle board and a method for manufacturing the same, and more particularly, to a high-strength particle board whose strength is enhanced by selecting particles (chips) and forming the same, and the like, and manufacturing the same. It is about the method.

[0002]

2. Description of the Related Art Particleboard is attracting attention as an alternative to plywood in today's world where environmental protection and effective use of resources are being called for. Generally, in the production of particle board, the specific gravity of the raw material is 0.5 to 0.
No. 7 is used, and the particle board is considered to be good if it satisfies JIS 100, 150, and 200 types in terms of strength. Conventionally, various types of high-strength particle boards and methods for manufacturing the same have been proposed. For example, a particle board has been proposed in which the upper and lower layers are small particle (small chip) layers, the intermediate layer is a large particle layer, and a reinforcing layer of a fiber material is interposed between the layers to provide strength, and a method of manufacturing the particle board. (JP-A-56-137949). Also, a method of manufacturing a particle board in which particles as raw material chips are previously treated with an aqueous alkali solution and heated and pressurized in steam has been proposed, and is provided as a particle board having a high strength and a low water absorption / swelling ratio. 58-14734
No. 5). Further, a method of manufacturing a particle board having a high peel strength has been proposed by applying a thin thermoplastic resin to a chip for a particle board, applying a thermosetting resin adhesive thereon, and applying heat and pressure (see, e.g. Kaisho 58
-41192).

[0003] In a method of manufacturing a particle board,
There are many literatures on the influence of the shape of particles as raw materials on physical properties. For example, bending strength (MO
R) increases with increasing length and thickness / width of the elements of the board, and peel strength (IB) increases with increasing thickness and decreasing length / width of the elements. On the other hand, the water absorption thickness swelling ratio (TS: index indicating dimensional stability) becomes better as the thickness / length decreases (Journal of the Wood Science Society, Vol 33 No 53).
76-384 Production technology of low specific gravity particle board). A particle board having a high compression ratio generally has an improved MOR, but has a poor puncture and TS (Materials Research Report, No. 292, 121-123, No. 2).
94 pp. 60-65 Workability of Papua New Guinea wood). Compared with the high specific gravity small pieces, the low specific gravity small pieces provide good adhesion between the small pieces at a constant board specific gravity, and therefore, the board material is improved (Holzforsch, U, Holzerwert 20,
Pages 1 to 10 '68 Stegmanm, G, & Bismark, C,
V).

[0004]

However, the conventional particle board passes the JIS standard (200 type), but has a bending strength (MOR) of 18 in a normal state.
It is about 0 kgf / cm ^2, which is lower in strength than plywood. For this reason, in order to use it for a residential building, it is necessary to further increase the thickness, and accordingly, the weight becomes excessively large, and there is a problem in handling it on site. Research on the relationship between the properties of particle boards and the shape of the particles that are the raw materials for them has been carried out as described above, but there are cases where bending strength and bending rigidity are increased and cases where the water absorption thickness swelling ratio is improved. In this case, the particle shapes are contradictory. Furthermore, although low specific gravity particles can be used and compacted at a high compression ratio to impart high bending strength and bending rigidity to the board, the springback of the board is increased and the water absorption thickness swelling ratio is deteriorated ( The dimensional change increases.) Further, in order to solve such a problem, it is conceivable that high specific gravity particles are mixed with low specific gravity particles, but the dimensional stability has not been improved.
In addition, it is considered that in the case of a particle board having a fiber sheet or the like interposed therein, the production thereof is complicated. Therefore, an object of the present invention is to make the thickness of the board itself thin and light, have sufficient strength applicable to a panel material for a house, and have a small water absorption thickness swelling ratio, that is, excellent dimensional stability. in the providing child high strength particle board and a manufacturing method thereof.

[0005]

Means for Solving the Problems The present inventors divide a particle board into a surface layer and an inner layer, and use specific particles for the surface layer and the inner layer to obtain a light-weight, extremely strong, and excellent dimensional stability. It has been found that a board can be formed and the above object can be achieved. The present invention has been made on the basis of the above findings, and scatters low-specific-gravity particles (chips) having a specific gravity of less than 0.5 on a conveying means, and
Form a surface layer of low specific gravity particles on the transfer surface, and then
Spread particles of medium / high specific gravity of 0.5 or more on the surface layer during transportation to laminate the inner layer, and further on the inner layer during transportation.
Spray low specific gravity particles with a specific gravity of less than 0.5 to make the surface layer
Laminate, pressing the surface layer of the laminate at a compression ratio of 1.5 or more
Obtained more to provide a high-strength particle board which can be used for paneling a residential, the
The purpose has been achieved . The present invention also provides a method of manufacturing the high-strength particle board, said conveying means
Of low or high specific gravity particles above
Provide a supply port, where the wind force or wind and electrostatic force
The particles of low specific gravity in the above particles are
Blown toward the front and rear transfer surfaces of the transfer means
More to provide a method of producing a high strength particle board, characterized in that cause or have to be oriented,
The above object has been achieved . Here, the compression ratio is the ratio of the board specific gravity to the raw material specific gravity (board specific gravity /
Raw material specific gravity).

Hereinafter, a high-strength particle board and a method of manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings. 1A and 1B are cross-sectional views of the high-strength particle board of the present embodiment. FIGS. 2A and 2B are explanatory diagrams of a high-strength particle board manufacturing apparatus of the present embodiment. The high-strength particle board according to the present invention is a laminate having an inner layer 2 between surface layers 1 and 3 as shown in FIG. The inner layer 2 is a single layer in FIG.
As long as the particles are composed of medium and high specific gravity particles, they may be formed in multiple layers and are not particularly limited.

[0007] The surface layers 1 and 3 are composed of low specific gravity particles 5A, which are made from low specific gravity material chips, whose specific gravity is less than 0.5, preferably less than 0.5.
1 to 0.4. The specific gravity of low specific gravity particles 5A is 0.
When it is less than 5, the bending strength and the bending rigidity of the particle board are improved. The shape of the particles of the surface layers 1 and 3 may be a normal shape having a thickness of 0.2 mm or more and a width of 1 mm or more, and particularly, an average particle length of 4 mm or more, particularly 4 to 15 mm. Desirably. When the length of the particles is 4 mm or more, the particle board has higher strength and higher rigidity. The inner layer 2 is a normal medium / high specific gravity particle having a specific gravity of 0.5 or more.
There is no particular limitation as long as it consists of 5B.

A general adhesive is used for the surface layers 1 and 3 and the inner layer 2, and these adhesives include, for example, furniture,
If it is a particle board for building materials, urea resin or the like can be used, and if it is for construction, melamine urea, melamine, phenol, isocyanate resin adhesive can be used, and it can be selected according to the application . The amount of the adhesive in the surface layers 1 and 3 is 8 to 15% by weight.
(The amount of the adhesive / the total dry amount of the particles × 100) is desirable, and the content of the inner layer 2 is desirably 5 to 15% by weight.
When the amount of the adhesive falls below the above range, it becomes difficult to obtain sufficient strength for the board. The overall thickness of a high-strength particle board is generally 9 mm or more, and the thickness of the surface layer is determined by the thickness of the board.

In order to further reinforce the high-strength particle board, it is preferable that the surface layers 1 and 3 contain reinforcing fibers. As shown in FIG. 1 (b), the surface layers 1 and 3 of the particle board have The reinforcing fiber 4 can be contained, and the reinforcing fiber 4 can include one or more kinds of fibers made of metal, inorganic, or organic. Examples of these fibers include metal fibers such as iron, copper, and aluminum, reinforcing fibers such as carbon and aramid, and chemical fibers made of phenol, epoxy, nylon, and the like. Further, the content of the reinforcing fibers 4 is preferably 10% by weight or more based on the particles.

[0010] In the high-strength particle board configured as described above, as will be apparent from embodiments described later, it has high strength, high rigidity, and high dimensional stability.

Next, a method for manufacturing a high-strength particle board according to the present invention will be described in detail with reference to FIG. The method for producing a high-strength particle board according to the present invention includes dispersing the low-specific-gravity particles 5A on a conveying means to form a surface layer of the low-specific-gravity particles 5A on the conveying surface of the conveying means, and then forming the surface layer during the conveying. Medium / high specific gravity particles 5B are scattered on the surface layer to form an inner layer, and low specific gravity particles
The surface layer is laminated by spraying 5A, and the surface layer of the laminate is pressed at a compression ratio of 1.5 or more.

The high-strength particle board apparatus shown in FIG. 2A using one embodiment of the present invention will now be described in more detail. , And the above-described low-specific-gravity particles 5 </ b> A are first scattered from the supply hopper 13 onto the transport belt 12. As a result, a low-specific-gravity particle layer A serving as a surface layer is formed on the surface of the transport belt 12. As the transport belt 12 moves, the low specific gravity particle layer A is located below the supply hopper 14, and the above-described medium / high specific gravity particles 5 </ b> B are scattered from the supply hopper 14 to the low specific gravity particle layer A. As a result, the medium / high specific gravity particle layer B serving as an inner layer in the low specific gravity particle layer A
Is formed.

As the transport belt 12 moves, the medium / high specific gravity particle layer B is positioned below the supply hopper 15, and the medium / high specific gravity particle layer B is placed on the supply hopper 15.
, Low specific gravity particles 5A are scattered. This allows
A low-specific-gravity particle layer C serving as a surface layer is formed on the low-specific-gravity particle layer A and the medium / high-particle layers B. When the transport belt 12 moves, and the laminate of A, B, and C is positioned between the press members 17 and 18 of the compression device 16, the compression device 16 operates and the laminate is compressed. You.
In this case, it is desirable to heat the press material and perform it at a high temperature and high pressure in the initial stage of pressing. When the initial stage of the pressing is performed at a high temperature and a high pressure, the bulky low specific gravity particle layers A and C can be compacted as fast as possible, the strength can be expected to be improved, and the precuring of the adhesive can be reduced. .
It is desirable that the compression ratio at this time is 1.5 or more. As a result of such pressing, a surface layer of the low specific gravity particles 5A and an inner layer of the middle and high specific gravity particles 5B are formed,
The above-described high-strength particle board can be easily obtained.

Next, another embodiment of the method for producing a high-strength particle board of the present invention will be described in detail with reference to the high-strength particle board apparatus of FIG. 2 (b).
A supply hopper 21 for supplying particles having a low specific gravity or a high specific gravity is provided, and the supply hopper 21 blows out the low specific gravity particles 5A in the particles toward the front transfer surface 12A and the rear transfer surface 12C of the transfer means by wind power. Like that. Also, a forming method in which an electric field is provided (anode and cathode) to orient particles by using electrostatic force together is also possible.

The above-mentioned manufacturing method will be described in more detail. The conveying device 11, the conveying belt 12, the pressing device 16, and the press members 17 and 18, which are the conveying means shown in FIG.
It has substantially the same members and structure as the device (a). However, only one particle supply hopper 21 is disposed above the transport belt 12, and the low specific gravity particles 5A and the medium / high specific gravity particles 5B are supplied from the supply hopper 21. Then, by adjusting the blow state in the supply hopper 21, the low specific gravity particles 5A are made to fly far and are scattered on the front conveying surface 12A and the rear conveying surface 12C of the conveying belt 12, thereby forming the medium / high specific gravity particles 5B. And drop it directly below to scatter it on the transfer surface 12B. In this way, a surface layer, an inner layer, and a laminate serving as a surface layer can be formed on the transport surface of the transport belt 12 in the same manner as in FIG. 2A, and a high-strength particle board is formed by the subsequent pressing device 16. be able to. The pressing device 16 may perform a continuous press.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a high-strength particle board and a method for manufacturing the same according to the present invention will be described in comparison with comparative examples. The present invention is not limited to the following embodiments. (Example 1) Based on the above-described manufacturing method, particles having a low specific gravity (pink satin: total specific gravity of 0.3
3, a medium having a thickness of 0.5 × width 1.5 × length 1 to 5 mm) and a medium specific gravity particle (red melanty: total dry specific gravity of 0.54 and a thickness of 0. A high-strength particle board was manufactured using a material having a size of 5 × 1.5 × 12.5 mm in length. In this case, surface layer: inner layer = 4
The ratio was 0:60, and the specific gravity of the production board was about 0.7. The bonding conditions were melamine-urea co-condensation resin (manufactured by Sumitomo Bakelite), the coating amount was about 10% by weight on the surface layer or the inner layer, and the pressing condition was 2.5 minutes, the initial
0 kg / cm ² . For the manufactured particle board, bending characteristics, water resistance, water absorption thickness swelling ratio, peel strength,
And evaluation of wood screw holding power was performed. The results are shown in Table 1.

(Comparative Example 1) Based on the same production method as in Example 1, a medium layer of specific gravity (red melanty: total specific gravity of 0.54, thickness 0.5 × width 1.5) was used as the surface layer.
X 12.5 mm in length, and medium specific gravity particles as inner layer (red meranty: total dry specific gravity is 0.54, thickness 0.5 x width 1.5 x length 12.5 mm)
A particle board was manufactured using the above. The same evaluation as in Example 1 was performed on the manufactured board, and the results are shown in Table 1. (Comparative Example 2) Based on the same manufacturing method as in Example 1, high specific gravity particles (Town: total dry specific gravity is 0.
64), and medium-density particles (red melanty: total dry specific gravity 0.54, thickness 0.5 × width 1.5 × length 12.5 mm) as the inner layer. Particleboard was manufactured. The same evaluation as in Example 1 was performed on the manufactured board, and the results are shown in Table 1.

(Comparative Example 3) Based on the same manufacturing method as in Example 1, low specific gravity particles (pink satin: total dry specific gravity: 0.33, thickness: 0.5 × width: 1.5) were used as the surface layer and the inner layer. × length 1-5 mm) to produce a particle board. The same evaluation as in Example 1 was performed on the manufactured board, and the results are shown in Table 1. (Comparative Example 4) Based on the same manufacturing method as in Example 1, as the surface layer and the inner layer, low specific gravity particles (pink satin: total dry specific gravity is 0.33, thickness 0.5 × width 1.5 × length) Particles using a mixture of particles having a specific gravity of 1 to 5 mm and a medium specific gravity (red meranty: total specific gravity of 0.54, thickness 0.5 × width 1.5 × length 12.5 mm) The board was manufactured. The same evaluation as in Example 1 was performed on the manufactured board, and the results are shown in Table 1.

The following experiments were conducted on the effectiveness of the length of the surface particles. (Reference Example 1) Based on the same production method as in Example 1 (note that only the adhesive was used in place of melamine resin (manufactured by Sumitomo Bakelite)), a medium specific gravity particle (red melanty: total dry specific gravity) was used as the surface layer. Is 0.54 and the thickness is 0.2
X 0.5 to 1.5 x 4.0 mm length or more and medium density particles (red meranty: dry specific gravity 0.54, thickness 0.5 x width 1) as inner layer .
Particle boards of 5 × 12.5 mm in length) were manufactured. The same evaluation as in Example 1 was performed on the manufactured board, and the results are shown in Table 1.

Reference Example 2 Based on the same manufacturing method as in Example 1, high specific gravity particles (red meranty: total dry specific gravity is 0.54, thickness 0.2 × width 0.5)
~ 1.0 × Length less than 4.0 mm) and medium specific gravity particles (red melanty: total dry specific gravity is 0.54, thickness 0.5 × width 1.5 × length) as inner layer Sa1
2.5 mm) to produce a particle board. The same evaluation as in Example 1 was performed for the production board,
The results are shown in Table 1.

[0021]

[Table 1] In addition, each evaluation test conforms to JISA5908.

From Example 1 and Comparative Examples 1 to 4, those containing low specific gravity particles only in the surface layer have high performance in both bending properties (flexural strength and rigidity of bending Young's modulus) and water resistance. Comparative Example 1 in which the surface layer and the inner layer contain ordinary red melanty (medium specific gravity particles) as a particle material, Comparative Example 2 in which the town (high specific gravity particles) is included in the surface layer, and low specific gravity and In the case of Comparative Example 4 in which the medium specific gravity particles are mixed, the bending strength satisfies the JIS 200 type, but is lower by 20 to 30% than that of Example 1. The bending rigidity is also low. In Comparative Example 3 in which only the low specific gravity particles are contained in the surface layer and the inner layer, the flexural strength is high but the water resistance is low. This is because the surface area of the particles is large,
This is probably because the adhesive is not sufficient, the degree of consolidation is deep, and the springback due to water absorption increases.
From Reference Examples 1 and 2 , the shape of the surface particles is
When the length of the particles is 4 mm or more, higher bending strength is exhibited as compared with the length of 4 mm or less. Therefore, by using particles having a low specific gravity and a long shape, a high-strength particle board with further enhanced strength can be manufactured.

[0023]

The high-strength particle board according to the present invention has a small thickness and light weight, has sufficient strength to be applied to a panel material for a house, and has excellent dimensional stability. Further, the method for manufacturing a high-strength particle board according to the present invention makes it possible to easily manufacture the particle board.

[Brief description of the drawings]

1 (a) and 1 (b) are cross-sectional views of a high-strength particle board according to the present embodiment.

FIGS. 2A and 2B are explanatory diagrams of a manufacturing apparatus for a high-strength particle board of the present embodiment.

[Explanation of symbols]

 1, 3 Surface layer 2 Inner layer 4 Reinforcing fiber 5A Low specific gravity particle 5B Medium / high specific gravity particle 11 Conveying device 11 12 Conveying belt 16 Pressing device 17, 18 Press material

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B27N 3/00-3/14

Claims (2)

(57) [Claims] 1. Low density particles having a specific gravity of less than 0.5
(Chips) are sprayed on the conveying means to form a surface layer of low specific gravity particles on the conveying surface of the conveying means, and then , medium and high specific gravity particles having a specific gravity of 0.5 or more are formed on the surface layer being conveyed. The inner layer is scattered and laminated, and the specific gravity is further placed on the inner layer during transportation.
A surface layer is laminated by spraying particles having a low specific gravity of less than 0.5, and the surface layer of the laminate is obtained by pressing at a compression ratio of 1.5 or more .
High-strength particle board that can be used for residential panel materials . 2. The high-strength particle bow according to claim 1.
A de production method, above the conveying means, arranged supply port for supplying the low-density or high density particles in said supply port, low density particles in the particle by the wind or wind and electrostatic forces Is blown or oriented toward the front and rear transfer surfaces of the transfer means.