JPH0735276B2 - Method for producing wood-containing gypsum board - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a wood-containing gypsum board.

[Prior Art] Generally, gypsum board is mixed with calcined gypsum as starch,
Add foaming agent and water-reducing agent, 0.2 to 0.3% as a reinforcing agent
Pulp is added and an appropriate amount of water is added to make a uniform calcined gypsum slurry, which is poured onto the cover of the gypsum board base paper, the backing paper is placed on it, and the rollers and parallel plates installed between the top and bottom. Alternatively, a predetermined thickness is obtained by passing between the parallel plate and the roller. After the calcined gypsum slurry is hardened, it is dried to obtain a product.

Gypsum board is widely used as a base material because it has excellent fire resistance, but it is a composite of cardboard for board with a thickness of about 0.4 mm and a fragile gypsum core in which bubbles with a bulk density of about 0.75 are mixed. About 60% of the strength of the board base paper contributes to the bending strength, so that it can withstand use, but it has the drawback that the holding power of the gypsum board itself, such as screws, is extremely low compared to other building materials.

[Problems to be Solved by the Invention] Therefore, it has been attempted to mix pulp or glass fiber into the gypsum board in order to improve the screw holding force and bending strength, but the diameter and width of the fiber are 10 to 10 100 μm, length 3 to 13 mm, length / diameter or width ratio 30 to 1300
Since the fine long fibers are used and the bulk increases when defibrated, even if mixed in a small amount, the fluidity of the calcined gypsum slurry required for forming the gypsum board sharply decreases.

In order to stably produce a gypsum board from the calcined gypsum slurry containing such fibers, the amount of the fibers mixed is limited to 1.0% of calcined gypsum. If more than 1.0% of the fibers are mixed, the dispersion of the fibers in the calcined gypsum slurry becomes poor, and the fibers become ball-shaped small lumps, which makes it impossible to produce a high-quality gypsum board. When 1% of these fibers are mixed, it is effective to some extent in improving the bending strength, but is not effective in improving the holding force of the screw. The reason is that the amount of fibers mixed in is small, so that the friction of the fibers does not effectively act on the screw portion.

In addition, about 10% of sawdust was mixed in place of the existing bubbles until an excellent foaming agent was developed. The shape of this sawdust is from a spherical shape with a diameter of 1 to 3 mm, and the length / width ratio is 1
Although it is a ~ 3 rectangular wood, the surface of the wood was smooth, there was no partial defibration, and no reinforcing effect was observed.

[Means for Solving the Problems] In the method for producing a wood-containing gypsum board according to the present invention, the wood has a thickness of less than 1 mm and a length of less than 10 mm, and the wood is partially defibrated so that the wood surface 1 The ratio a '/ a of the maximum width including the fibers disentangled from the part / the maximum width of wood is 2 to 10,
Maximum length including fibers disentangled from part of the wood surface /
Manufacture of wood-containing gypsum board characterized in that the maximum length ratio b '/ b of wood is 1-3, the length / width ratio is 3-10, and the water content of wood is 30% or more. There is a way to provide.

[Operation] The wood-containing gypsum board produced by the method of the present invention has a thickness
Less than 1mm, less than 10mm in length of wood, 1 of wood surface
Ratio of maximum width (a ') including fibers disentangled from the part and maximum width of wood (a) a' / a = 2 to 10, and ratio of similar lengths b '/ b = 1 to 3 30% moisture content that was partially defibrated
It uses the above wood and has a length / width ratio of 3
Needles to produce gypsum board, unlike the case of using pulp or glass fiber with a length / diameter or width ratio of 30 to 1300 even if it is mixed in a large amount because it is needle shape of ~ 10 The fluidity of the calcined gypsum slurry is not impaired (the relationship between a '/ a and b' / b is shown in Fig. 1).

The above wood quality is 1 to 15% based on the weight of calcined gypsum.
Can be mixed. If the content of wood is less than 1%, it is not preferable because the effect of addition is not exhibited, and if it exceeds 15%, the amount of mixing water for obtaining the softness required for forming gypsum board increases, and as a result, gypsum is obtained. This is not preferable because the slurry and the wood are separated, the fluidity is deteriorated, and board molding becomes difficult.

Since pulp and glass fibers are long and slender, fibers intermingle in the longitudinal direction of the gypsum board, and the improvement in bending strength is remarkable in the plane perpendicular to the longitudinal direction (longitudinal direction), and in the plane parallel to the longitudinal direction (lateral direction). Is not very effective in improving On the other hand, since the wood used in the method of the present invention has a length / width ratio of 3 to 10 and a part of the wood surface is partially defibrated and the rest is an undefibrated part, the direction of the defibrated fibers Is not constant, it has no directionality and can be randomly mixed.

The plasterboard mixed with wood, which can be mixed in a large amount and can be randomly mixed as described above, can particularly improve the holding power of the screw and the bending strength in the longitudinal and lateral directions.

In addition, the size of the above-mentioned wood is 2 mm or more in thickness and 10 m in length.
When it is more than m, the fluidity of the calcined gypsum slurry is extremely deteriorated, which is not preferable. Particularly good fluidity is obtained when using wood with dimensions less than 1 mm thick and less than 5 mm long.

The wood used in the method of the present invention is, for example, raw wood with a shaving machine.
Roughly cut to about 5 mm, width 1 to 4 cm, length 3 to 5 cm, and
0.2 to 1.2 mm thick, 1 to 10 mm wide, 10 to 40 mm long with a shaving machine
It is possible to make thin pieces of a certain degree, crush the obtained thin pieces, and partially decompose the fibers with a defibrating machine to obtain a wood material of a desired shape.

The wood-containing gypsum board can be manufactured on a conventional gypsum board manufacturing line. For example, preliminarily mix defibrated wood and calcined gypsum, then mix with water with a mixer to make a uniform calcined gypsum slurry, pour it on the cover of the gypsum board base paper, place the backing paper on it, It can be obtained by setting rollers to have a desired thickness through a roller installed between the upper and lower sides, a parallel plate, or a space between the parallel plates and the rollers, hardening the calcined gypsum slurry, and then drying.

In addition, when manufacturing a wood-containing gypsum board, a conventional additive can be added to the calcined gypsum slurry.

[Examples] Example An example of forming a calcined gypsum slurry having a composition of to be described below, pouring this on a gypsum board base paper, placing a backing paper on it, and using a conventional gypsum board production line 910 x 1
A gypsum board having a shape of 820 × 12 (mm) was obtained.

95 parts by weight of water, 1 part by weight of polyvinyl alcohol, 0.6 parts by weight of water reducing agent, 0.023 parts by weight of foaming agent and width of 100 parts by weight of calcined gypsum
Pulp with a length of 15 to 100μ and a length of 0.5 to 3mm was added and mixed to make a slurry (reference product).

95 parts by weight of water, 1 part by weight of polyvinyl alcohol, 0.6 parts by weight of water-reducing agent, 0.023 parts by weight of foaming agent and glass fiber of 10 μm in diameter and 12.5 mm in length were added and mixed into 100 parts by weight of calcined gypsum to form a slurry (reference. Goods).

100 parts by weight of calcined gypsum, 95 parts by weight of water, 1 part by weight of polyvinyl alcohol, 0.8 parts by weight of water reducing agent, 0.019 parts by weight of foaming agent and 0.5 mm or less in thickness, less than 10 mm in length, a '/ a = 2 to 10, b' / b
= 1.1 to 1.8, sieve opening 1.19mm, residual 56.4%, 0.2mm
A slurry was prepared by adding and mixing 3 parts by weight of red pine wood with a residue of 94.7% and a water content of 48% (product of the present invention).

100 parts by weight of calcined gypsum, 100 parts by weight of water, 1 part by weight of poval,
0.8 parts by weight of the water reducing agent, 0.019 parts by weight of the foaming agent, and 7 parts by weight of the same wood as that used for the mixture were added and mixed to obtain a slurry (product of the present invention).

100 parts by weight of calcined gypsum, 110 parts by weight of water, 1 part by weight of poval,
0.8 parts by weight of a water-reducing agent, 0.019 parts by weight of a foaming agent, and 14 parts by weight of the same wood as that used for the addition and mixing were made into a slurry (product of the present invention).

100 parts by weight of calcined gypsum, 100 parts by weight of water, 1 part by weight of poval,
0.8 parts by weight of water reducing agent, 0.019 parts by weight of foaming agent and diameter of Akamatsu 2
A slurry was prepared by adding and mixing 10 parts by weight of 3 mm sawdust (reference product).

80 parts by weight of water and 1 part by weight of Poval were added to 100 parts by weight of calcined gypsum and blended into a slurry (reference product).

The characteristics and waterproof performance of the obtained gypsum board are shown in Tables 1 and 2 below.

The fire protection test was performed according to JIS A 1321.

As described above, the bending strength of gypsum board is 4 times that of the core.
The strength of the base paper for gypsum board contributes 60%. Since the pulp is arranged in the flow direction of the base paper when the base paper is made into paper, the tensile strength differs between the longitudinal direction and the transverse direction, and the lateral / longitudinal ratio of the tensile strength is 0.40 to 0.45. Therefore, the lateral / aspect ratio of the bending strength of the gypsum board is usually 0.40 to 0.45 (the gypsum board obtained by using the slurry of ,, and). However, when the wood material having the characteristics within the range of the present invention was used, the lateral / aspect ratio of the bending strength was 0.49 to 0.58, which was a value exceeding almost 0.50. This value is 1 that wood is randomly crossed
It is considered to be one proof.

Further, when the wood-containing gypsum board of the present invention obtained by using the slurry of ~ is cut and the cut surface is visually observed,
I felt that there was a little more wood in the vertical direction.

[Effects of the Invention] The wood-containing gypsum board produced by the method of the present invention has a strong screw holding force, a high bending / width ratio of about 0.50 or more, and is excellent in fire prevention performance.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a '/ a ratio and b' / b ratio of wood.

Claims (1)

[Claims] 1. A method of manufacturing a wood-containing gypsum board, comprising:
The ratio of maximum width / maximum width of wood is a '/, in which the wood is less than 1 mm thick and less than 10 mm long, and the wood is partially defibrated to include fibers defibrated from a part of the wood surface. a is 2 to 10 and the ratio b ′ / b of the maximum length including the fibers defibrated from a part of the wood surface / the maximum length of wood is 1 to 3 and the length /
A method for producing a wood-containing gypsum board, which has a width ratio of 3 to 10 and a water content of wood of 30% or more.