JPS60246248A - Manufacture of excelsior cement board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing wood cement boards, which are widely used as building materials.

BACKGROUND ART The wood chip cement boards currently on the market have large wood chip shapes (for example, the classification range is 5.0 to 10, which passes through a sieve with an opening size of 10 mm and stays on a sieve with an opening size of 5.0 mm. A single-layer, coarse-grained type manufactured using wood chips as a raw material, and a large wood chip-shaped (
For example, if the raw material is wood chips (with a classification range of 5.0 to 10), the surface layer will pass through a sieve with a small wood chip shape (for example, with an opening size of 5.0 mm), and then pass through a sieve with an opening size of 0.5.0 mm. There is a dense type with a three-layer structure manufactured from wood chips (with a classification range of 0.5 to 5.0). Rough type molded products lack density, resulting in high water absorption and significant dimensional changes, and furthermore, they suffer from significant damage when subjected to freeze-thaw action in a water-absorbed state. The intensity of the song is also significantly lower. The dense type has a three-layer structure, making the manufacturing process complicated.

Furthermore, since the shape of the wood piece differs between the surface layer and the center layer, the sheet metal body lacks homogeneity, resulting in significant warping as the board absorbs water and dries. In addition, a three-layer board using pieces of wood that go down to the surface layer that are larger than the center layer was published in JP-A-54-1.
No. 33511 and Japanese Patent Application Laid-Open No. 55-4439, but these also have the same defect of lack of homogeneity of the plate.

Problems to be Solved by the Invention It is an object of the present inventor to provide a method for manufacturing a wood cement board having high strength and good dimensional stability, which eliminates the drawbacks of the conventional wood cement board.

Means for Solving the Problems The present inventor has devised a method for producing a wood cement board that is dense and homogeneous throughout and has high bending strength by mixing and using wood chips within a specific particle size range. This led to the invention. That is, in the present invention, the length is 2.0 to 1ON, the width is 0
．． 5-2-On, aspect ratio (wood chip length/thickness ratio) of wood chips ranging from 5 to 50 and lengths of 10 to 251
m, width 2.0-5. O,J.

It is characterized by mixing wood chips with an aspect ratio of λ to 100, adding water and cement, kneading the mixture, forming the mixed material into a plate, and then curing and hardening the cement under moist heat. This is a method for manufacturing wood chip cement boards.

Function: In the production of wood cement boards, the present invention crushes raw wood chips with a flaker to obtain wood chips in the form of flakes, which are then passed through a sieve with a sieve opening size of 0.5 to 2.0.
w 1 [I range (hereinafter referred to as classification range 0.5-2.0) and 2.0-5. OIIJ range (hereinafter classification range 2.0~
(denoted as 5.011J) K classification, and these wood chips are mixed and used as raw material wood chips. The classification range is 5.0. If the shape of the wood piece is too large in the above conditions, the filling properties will be poor and defects will occur, resulting in a decrease in bending strength. Furthermore, if the classification range is 0.51 IJ or less and the shape of the wood piece is too small, the phenomenon of poor curing of cement will occur, making it impossible to obtain a normal molded board. The mixing ratio of wood chips at this time is:
Weight ratio 1 (classification range 0.5 to 2.0 IIx):
The weight ratio is preferably 0.25 to 4.0 (classification range 2.0 to 5.0), but preferably about 1:O,S to 1.5.

Add water and cement to the mixed raw wood chips and knead them, then form this mixture into a pressed steel plate,
Pressure mold and clamp. Next, the cement is heated and cured at 40 to 80° C. in the clamped state to harden the cement, and then removed from the mold.

The product is then aged and cured indoors for about 20 days, along with curing and moisture adjustment of the board. As described above, the manufacturing process of the wood chip cement board according to the present invention is no different from the conventional single-layer wood chip cement board manufacturing process, and does not require complicated processes, but can be achieved by combining wood chips in a specific particle size range. This is a new manufacturing method that can significantly improve physical properties.

The wood chip cement board obtained by the present invention is dense and homogeneous as a whole due to the close packing of wood chips, has a low water absorption rate, and has low thickness swelling and warpage due to water absorption and drying. Furthermore, since it is dense and homogeneous and has no defects, its bending strength is extremely high. In addition, simply 0.5 to 5.0. Wood chips that have been single-classified within a range cannot exhibit such an effect due to the influence of particle size distribution.

At the same time, the present invention also makes it possible to manufacture a 4ffliit wood cement board that has strength comparable to that of conventional wood cement boards and has excellent workability and workability.

The effect of increasing the bending strength, reducing the water absorption rate and the thickness swelling rate of the dense and homogeneous wood cement board according to the present invention will be explained below using Examples.

Example A hemlock tree species was crushed into particles using a Bahlmann 811JPZ-s type flaker, and the sieve opening size was 0.84 to 2.0 mm using a vibrating sieve. Ou range of wood chips and 2.0 to 4.
It was classified into wood chips in the On range. Using these two types of wood chips as wood chips and ordinary Portland cement as cement, a molded plate was obtained using the following blending composition and molding method.

<Blending ratio> Cement 0.50 folded part Water 0.32 # Wood chips 0.18 # (0.84 to 2. OIJ range and 2.0 to 4.0 volume range k M ki ratio 1 : mixed with 1) 0.84
Classified into ~2.0 ms range and fc mononoke length 2.0 ~ l
O recommendation, width 0.84-2.01LI+, aspect ratio 5
~30, and 2.0 to 4. Those classified into the Oy range have a length of 1O-25Ul and a medium size of 2.0 to 4.01+3.
The aspect ratio was in the range of 25-70. The above two types of wood chips were mixed at a weight ratio of 1:1, water and cement were added thereto, and the mixture was thoroughly mixed using a mortar mixer.

This kneaded material was formed in a press steel plate of a predetermined size, press-formed with a pressure of 25 kg/c#l, and clamped. 40℃-Rn in clamped state, 2 at 100%
After curing for 0 hours, it was demolded at 20℃-R, ) (7 at 100%)
A molded plate was obtained by aging and curing for one day.

Comparative Example 1 Wood chips classified into a range of 0.84 to 2.0 U were used alone, and the blending ratio of raw materials and other molding conditions were the same as in the example.

Comparative Example 2 Wood chips classified into a range of 2.0 to 4.0 were used alone, and the blending ratio of raw materials and other molding conditions were the same as in the example.

Comparative Example 3 Hemlock tree pieces crushed into flakes with a flaker were passed through a vibrating sieve with a sieve opening size of 0.84 to 4, Osu+
il) The wood chips were classified and used as raw material wood chips, and the blending ratio of raw materials and other molding conditions were the same as in Examples.

Regarding the molded plates obtained in the above Examples and Comparative Examples, bending strength (test body dimensions 12 x 50 50 x 50 m++,
Full surface immersion test) and thickness swelling rate due to water absorption (rate of change in plate thickness from the start of air drying to 7 days of water absorption) were measured. The results are shown in Table 1.

1st Clothing *The absolute dry bulk density of the above test specimens is K 1 for both Examples and Comparative Examples.
．． 2 (?/cTl).

Effects of the Invention According to the manufacturing method of the present invention, as shown in the examples, a wood chip cement board with extremely high bending strength, low water absorption, and small dimensional change can be obtained.

Patent applicant: Asahi Kasei Industries, Ltd.

Claims (1)

[Claims] Length 2.0 = 10 Km, width 0.5~2.011J
1 Aspect ratio (wood chip length/thickness ratio) 5 to 5
Wood chips in the range 0, length 10-25, width 2.0-
5. Ou1 is mixed with wood chips having an aspect ratio of 25 to 100, and further water and cement are added and kneaded,
A method for producing a wood chip cement board, which is characterized by forming this mixed material into a board, and then curing and hardening the cement under moist heat.