JP2003262034A - Gypsum board and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gypsum board capable of adsorbing formaldehyde and offering good exterior appearance. <P>SOLUTION: The gypsum board 10 is manufactured by pouring slurry obtained by mixing the raw materials such as gypsum or the like together with water into the gaps in base paper 12 and then forming and drying; and the base paper 12 is arranged on the front and rear surfaces of the gypsum core layer 11. Near the boundary between the base paper 12 and the gypsum core layer 11, an adsorption region 13 is formed from the center portion of the base paper 12 to the outer surface side of the gypsum core layer 11 as to the thickness direction of the gypsum board 10. This adsorption region 13 is formed by pouring main slurry S1 after coating slurry S2 containing a high concentration of formaldehyde has been applied on surface of the inner surface sides of the base paper 12, therefore, yellowish colors or uneven colors caused by coating the formaldehyde adsorbing agent as conventionally occurred can be fully avoided and the gypsum board 10 with excellent exterior appearance can be produced. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a gypsum board.

[0002]

2. Description of the Related Art In recent years, the diffusion of formaldehyde into the room from adhesives used for building materials has been regarded as a problem, and various standards such as "Japan Housing Performance Indication Standards" and "Evaluation Standards" for buildings have been considered. There are items related to formaldehyde. Under these circumstances, building materials that have the capability of capturing formaldehyde have been adopted.

Conventionally, as such a building material, there is a gypsum board described in JP-A-10-337803.
This gypsum board has a structure in which a formaldehyde scavenger is applied to the outer surface of the board base paper.

[0004]

However, in the above-mentioned conventional gypsum board, the formaldehyde scavenger is applied to the outer surface of the board base paper, so that the board base paper suffers from yellowing or color unevenness, which impairs its appearance. There was a flaw. The present invention was completed in view of the above circumstances, and an object thereof is to provide a gypsum board capable of adsorbing formaldehyde and having an excellent appearance.

[0005]

As a means for achieving the above object, the invention of claim 1 is a gypsum board in which base board for board is arranged on the front and back surfaces of a gypsum core material. Is characterized in that it has a formaldehyde adsorption region containing a formaldehyde adsorbent on the inner surface side thereof.

The formaldehyde adsorbent may be a compound having an amino group or an amide group, a compound such as a hydrazine derivative, a compound capable of reacting with an aldehyde having a carbonyl group such as phenols, sulfites or sulfites. .

According to a second aspect of the present invention, in the first aspect, the formaldehyde adsorbent is a hydrazide compound such as dihydrazine adipate, and the hydrazide compound is added to 100 parts by weight of calcined gypsum in a gypsum board. Is contained in an amount of 0.1 to 0.5 parts by weight.

According to a third aspect of the present invention, a gypsum which is made by mixing a raw material of a gypsum core material with water is poured between base papers for forming the front and back surfaces of a gypsum board, formed into a predetermined shape, and then dried. In the method for producing a board, a formaldehyde adsorbent is previously distributed on the inner surface side of one of the board base papers, and the slurry is poured onto the adsorbent.
Further, it is characterized in that the formaldehyde adsorbent is distributed on the inner surface side of the other board raw paper before the other board raw paper is stacked.

According to a fourth aspect of the present invention, according to the third aspect, at least a slurry from a mixing tank for mixing the formaldehyde adsorbent with a slurry obtained by mixing the raw material of the gypsum core material with water is used. It is characterized in that it is coated on the inner surface side of the base paper for the front side.

According to a fifth aspect of the invention, in the fourth aspect, the slurry is defoamed in the mixing tank.

[0011]

<Advantages and effects of the invention><Invention of claim 1 or 3> Since the formaldehyde adsorption region containing the formaldehyde adsorbent is present on the inner surface side of the board base paper, yellowing and color unevenness occur on the outer surface side of the board base paper. It is difficult to make the gypsum board excellent in appearance.

<Invention of Claim 2> When a hydrazide compound such as dihydrazine adipate is used, a high formaldehyde adsorption performance can be obtained.

<Invention of Claim 4> Since the formaldehyde adsorbent is mixed into the slurry, fluidity is obtained, and the base paper for board is easily coated.

<Invention of Claim 5> When the defoaming treatment is applied, the slurry easily penetrates into the board base paper.
The adhesiveness between the board base paper and the gypsum core material is improved.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the accompanying drawings. Gypsum board 10 of the present embodiment
Is produced by pouring a slurry obtained by mixing a raw material such as gypsum and water into board base paper (hereinafter, simply referred to as “base paper”) 12, 12 for molding and drying (FIG. 1). reference). Hereinafter, a method for manufacturing the gypsum board 10 will be described in detail.

The gypsum board manufacturing method according to the present embodiment forms the gypsum board 10 while moving the base paper 12 on a conveyor as shown in the schematic view of FIG.
The lower raw paper 12L is supplied from the right side of FIG.
(The raw paper on the side facing the interior side when the gypsum board is installed: the raw paper on the front side), and the upper raw paper 12U (back side raw paper) supplied from the upper left of the figure. First, water is added to calcined gypsum and pre-foamed foam, starch as an adhesion aid, a hardening accelerator, a dispersant, and other additives, and the mixture is put into a mixer M and mixed and stirred to form a slurry. Here, the slurry has a density of the gypsum board 10 after drying of 0.65 to 0.7.
It is prepared to be 0 g / cm ³ .

Most of the slurry mixed by the mixer M is sent to the slurry supply section D, and a part thereof is sent to two pumps P (corresponding to "mixing tank" in claim 4). The slurry sent to the slurry supply section D is used as the main slurry S1 for forming the gypsum core material layer 11 and is used as the lower raw paper 12
It is poured on L.

Now, the formaldehyde adsorbent is added to the slurry sent to both pumps P from the tank T in the pump P, and the slurry is sufficiently mixed and stirred, and at the same time,
A defoaming treatment is performed to reduce the bubbles contained in the slurry. Thus, the coating slurry S2 containing the formaldehyde adsorbent at a high concentration is obtained. Since the coating slurry S2 is subjected to the defoaming treatment, the adhesiveness with the base paper 12 is improved and the concentration of the formaldehyde adsorbent contained in the coating slurry S2 is increased. By the way, in the present embodiment, dihydrazine adipate is used as the formaldehyde adsorbent, and a 10% to 20% suspension solution of dihydrazine adipate is added to the slurry.

The coating slurry S2 is supplied to the pump P.
To the coating roll R. The coating roll R is arranged on the line before the base paper 12 reaches the slurry supply section D, and the inner side of the base paper 12 (the gypsum core material layer 11 side)
Then, the coating slurry S2 is applied to a uniform thickness. In this embodiment, the coating roll R has a coating slurry S2 of 0.1 mm.
It is set to apply a thickness of 0.5 mm to 0.5 mm. Here, the coating thickness of the coating slurry S2 on the base paper 12 may be at least within the range of 0.1 mm to 1.0 mm. The coating thickness of 0.1 mm or more is for exhibiting sufficient formaldehyde adsorption performance. The reason why the coating thickness is 1.0 mm or less is that the coating slurry S2 may become excessive and the adsorption layer 13 may spread too deep inside the gypsum core material layer 11.

The lower raw paper 12L coated with the coating slurry S2 is sent to the slurry supplying section D, and the lower raw paper 12L.
The main slurry S1 is poured onto the upper part and then sent to the forming section F. The forming part F is configured such that the upper raw paper 12U passes through the inside thereof, and is formed to have a predetermined uniform thickness in the process of the lower raw paper 12L into which the main slurry has been poured, and the upper portion of the upper surface of the main slurry S1. 12U of base paper is addressed. After passing through the forming part F, the gypsum board 1 is cut into a plate of a predetermined size and sufficiently dried.
0 is produced. Although not shown, the base paper 12 used in the present embodiment is made in multiple layers in the thickness direction, and the coating slurry S2 applied to the inner surface side of the base paper 12 permeates to the outer surface side in the intermediate layer. A waterproof layer is formed to limit this.

The gypsum board 10 manufactured as described above has a base paper 12 and a gypsum core material layer 1 as shown in FIG.
An adsorption region 13 is formed near the boundary with 1. The suction area 13 is the base paper 1 in the thickness direction of the gypsum board 10.
The formaldehyde adsorbent is formed in a high concentration in the adsorption region 13 from the substantially central portion of the gypsum core 2 to the outer surface side of the gypsum core material layer 11. Here, the adsorption area 13 is applied from the side of the gypsum core material layer 11 of the base paper 12 and penetrates into the base paper 12, but does not reach the outer surface. As a result, unlike the conventional one, the gypsum board 10 having an excellent appearance can be obtained without causing yellowing or color unevenness due to the application of the formaldehyde adsorbent on the outer surface of the base paper 12.

Subsequently, in order to evaluate the formaldehyde adsorption performance of the gypsum board 10 produced as described above, the following Examples 1 and 2 and Comparative Examples 1 and 2 were produced. Example 1 Based on the above manufacturing method, the gypsum board 10
Example 1 was manufactured in which the adsorption regions 13 were formed on both front and back sides. Here, the formaldehyde adsorbent (dihydrazine adipate) is 0.1 part by weight in each of the adsorption layers on the front side and the back side with respect to 100 parts by weight of calcined gypsum of the entire gypsum board 10, and 0.2 parts by weight in total. Was added so that the ratio would be.

[Embodiment 2] The embodiment 2 is different from the embodiment 1 in that the adsorption area 13 is formed only on the front side of the gypsum board 10 as shown in FIG. The formaldehyde adsorbent is added at a ratio of 0.1 part by weight only on the front side with respect to 100 parts by weight of calcined gypsum of the entire gypsum board 10. Other points are the same as those in Example 1.

Comparative Example 1 As shown in FIG. 4, a gypsum board of Comparative Example 1 was manufactured in which the front and back of the gypsum core material layer 21 were covered with base papers 22 and 22. The gypsum board of this comparative example is different from that of Example 1 in that the formaldehyde adsorbent was distributed throughout the gypsum core material layer 21. This example is manufactured by adding a 10% suspension solution of dihydrazine adipate to the slurry forming the gypsum core material layer 21, and the formaldehyde adsorbent is added to 100 parts by weight of calcined gypsum. Is added in an amount of 0.2 parts by weight.

[Comparative Example 2] In this comparative example, calcined gypsum 1 was used.
It was different from Comparative Example 1 in that the formaldehyde adsorbent was added in an amount of 0.1 part by weight with respect to 00 parts by weight, and other points were the same as in Comparative Example 1.

<Evaluation of Formaldehyde Adsorption Performance> First,
2 in a 45 liter closed container in a room at 25 ° C
Two 0 cm square commercial plywood sheets were left to stand to release the formaldehyde contained in the plywood, and the formaldehyde concentration in the closed container after 24 hours was measured, and the concentration at this time was taken as the initial concentration.

Then, about each Example and Comparative Example, 10
Prepare a square plate piece of cm square and plate thickness 1.25 cm,
A test piece was prepared by coating the other 5 surfaces excluding the surface with aluminum tape, and the test piece was allowed to stand in a closed container after measuring the initial concentration, and after 6 hours, 24 hours, and 48 hours. After 120 hours, the formaldehyde concentration in the closed container was measured to evaluate the formaldehyde adsorption performance of each Example and Comparative Example. The measurement results of each Example and Comparative Example are shown in Table 1.

[0028]

[Table 1]

Further, in order to evaluate the re-emission performance, each test piece whose formaldehyde adsorption performance was measured was
The mixture was allowed to stand in a closed container of 45 liters having a formaldehyde concentration of 0 ppm and the temperature was kept at 40 ° C. Then, the formaldehyde concentration in the closed container after 24 hours was measured. The measurement results of each Example and Comparative Example are shown in Table 1.

In the present embodiment, the formaldehyde concentration is measured by an air suppler (S-21 type) manufactured by Komei Rikagaku Kogyo Co., Ltd. and a formaldehyde detector tube (710).
Type) was used.

Regarding formaldehyde adsorption performance, Table 1
As shown in FIG. 3, the ones of Examples 1 and 2 have a lower formaldehyde concentration in the closed container than those of Comparative Examples 1 and 2. That is, it was found that the formaldehyde adsorption performance was excellent. Even if the same amount of formaldehyde adsorbent is contained, all formaldehyde adsorbent is distributed in the region close to the base paper as in Examples 1 and 2, so that formaldehyde can be adsorbed reliably. It seems that In addition, although Example 1 and Example 2 show the same adsorptivity at the initial stage of measurement, Example 1 is superior in adsorptivity over time. This is probably because in Example 1, the formaldehyde that has passed through the gypsum core material layer 11 is adsorbed in the adsorption region on the back side with the passage of time.

Regarding the formaldehyde re-emission performance, the formaldehyde concentration in the closed container after 24 hours was 0 ppm in both Examples 1 and 2, so that formaldehyde was not re-emitted in both cases. On the other hand, in Comparative Examples 1 and 2, the formaldehyde concentrations were 0.20 ppm and 0.40 ppm, respectively, which indicates that formaldehyde was re-emitted from the test piece. Therefore, it was proved that those of Examples 1 and 2 were difficult to re-release. This is because the formaldehyde adsorbed on the gypsum board 10 is incorporated into the dihydrazine adipate by a chemical reaction, that is, chemically adsorbed, and the formaldehyde adsorbed in close contact with the fibers of the base paper 12, that is, physically. Some are adsorbed. At this time, when the temperature rises after adsorbing formaldehyde, the chemically adsorbed ones are adsorbed as they are, but the physically adsorbed ones are released again. However,
Even in such a case, in the case of Examples 1 and 2, the base paper 1
Since the adsorption area 13 is formed even in the inside of 2, the formaldehyde re-emitted from the base paper 12 can be adsorbed by the adsorption layer, and diffusion from the gypsum board 10 can be prevented. Seem.

As described above, the gypsum board 1 of this embodiment
In No. 0, the formaldehyde adsorption performance is excellent, and the adsorption region 13 for exhibiting this formaldehyde adsorption performance is formed from the base paper 12 to the gypsum core material layer 11, so that the outer periphery of the base paper 12 is different from the conventional one. The appearance of the gypsum board 10 can be made excellent without causing yellowing or color unevenness on the surface.

Further, since the formaldehyde adsorbent is present at a high concentration on the outer surface side of the gypsum board 10, the formaldehyde present around the gypsum board 10 is greater than that in the case where the formaldehyde adsorbent is added to the entire gypsum board 10. It is easy to adsorb. Further, even when the formaldehyde physically adsorbed on the gypsum board 10 is re-released due to a temperature rise or the like, the adsorption area 1 reaches the inside of the base paper 12.
Since No. 3 is formed, the re-emitted formaldehyde can be easily adsorbed in the adsorption region 13 and diffusion from the gypsum board 10 can be prevented.

Further, by using a nitrogen-containing compound such as a hydrazide derivative such as adipic acid dihydrazine, a high formaldehyde adsorption performance can be exhibited, and since the formaldehyde adsorbent may be distributed only in the surface layer region, expensive formaldehyde is adsorbed. The amount of adsorbent used can be suppressed and it is highly economical. Further, in order to exert the same formaldehyde adsorption performance as that of Example 1 or 2 with the structure of Comparative Example 1 or 2, the density of the formaldehyde adsorbent in the entire gypsum core material layer must be increased. I won't. However, when the density of the formaldehyde adsorbent in the gypsum core material layer is increased in this way, the cost of the gypsum core material layer is lowered and the strength of the gypsum core material layer is deteriorated, thereby impairing the original function of the gypsum board. On the contrary,
In the present embodiment, most of the gypsum core material layer does not contain a formaldehyde adsorbent, and the strength is secured. That is, the gypsum board 10 of the present embodiment can have the original strength of the gypsum board while exhibiting high adsorption performance.

<Other Embodiments> The present invention is not limited to the embodiments described above and illustrated in the drawings. For example, the following embodiments are also included in the technical scope of the present invention. In addition to the above, various modifications can be made without departing from the scope of the invention. (1) In the above examples, dihydrazine adipate was used as the formaldehyde adsorbent, but not limited to this, compounds having an amino group or an amide group, compounds such as hydrazine derivatives, carbonyl groups such as phenols, sulfites or sulfites, etc. Any compound that reacts with aldehydes having

(2) In the above embodiment, the coating roll R is
The coating slurry S2 is applied to both the lower base paper 12L and the upper base paper 12U, but the coating slurry S2 is applied only to either the lower base paper 12L or the upper base paper 12U. Is also good. (3) In the above-described embodiment, the coating slurry S2 mixed with the formaldehyde adsorbent is applied to the base paper 12. However, for example, a powdery formaldehyde adsorbent is sprayed on the slurry before the base paper is attached or the base paper. It may be sprayed on the inner surface side of.

[Brief description of drawings]

[Figure 1] Cross-section of gypsum board

FIG. 2 is a schematic diagram of a method for manufacturing a gypsum board.

FIG. 3 is a sectional view of a gypsum board according to a second embodiment.

FIG. 4 is a cross-sectional view of a gypsum board according to Comparative Example 1 or Comparative Example 2.

[Explanation of symbols]

10 ... Gypsum board 11 ... Gypsum core material layer 12 ... Board base paper 13 ... Adsorption area (formaldehyde adsorption area) P ... Pump (mixing tank)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takumi Fujita             15-2 Sumiyoshi-cho, Yokkaichi-shi, Mie Chiyodau             ATE Co., Ltd. F term (reference) 2E001 DH28 FA10 GA42 HA03 HC07                 2E110 AA64 AB23 BA03 BA12 GA08W                       GB16                 2E162 CA16                 4F100 AE06A AH02B AH02C AH02H                       AH03B AH03C AH03H BA03                       BA06 BA10B BA10C BA13                       CA30B CA30C DG10B DG10C                       EH312 EH462 EH761 EJ862                       GB07 JD14B JD14C YY00B                       YY00C

Claims (5)

[Claims] 1. A gypsum board in which base paper for boards is arranged on the front and back surfaces of a gypsum core material, wherein a gypsum board containing a formaldehyde adsorbent containing a formaldehyde adsorbent is provided on the inner surface side of the base paper for board. . 2. The formaldehyde adsorbent is a hydrazide compound such as dihydrazine adipate,
The gypsum board according to claim 1, wherein 0.1 to 0.5 parts by weight of the hydrazide compound is contained with respect to 100 parts by weight of calcined gypsum in the gypsum board. 3. A method for producing a gypsum board in which a slurry obtained by mixing a raw material for a gypsum core material with water is poured between base paper sheets for forming the front and back surfaces of the gypsum board, formed into a predetermined shape, and then dried. , The formaldehyde adsorbent is previously distributed to the inner surface side of one board base paper, the slurry is poured on it, and before the other board base paper is stacked, the inner surface side of the other board base paper A method for producing a gypsum board, characterized in that the formaldehyde adsorbent is distributed in the. 4. A slurry from a mixing tank for mixing the formaldehyde adsorbent with a slurry prepared by mixing the raw material of the gypsum core material with water is applied onto at least the inner surface of the board base paper on the front side. The method for producing a gypsum board according to claim 3, which is characterized by the above-mentioned. 5. The method for producing a gypsum board according to claim 4, wherein the slurry is defoamed in the mixing tank.