JP2714668B2 - Humidity control material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a novel humidity control material (hereinafter, simply referred to as a humidity control material).

2. Description of the Related Art In the present specification, the term "humidity control" means that the humidity environment in the interior of a building and various storage spaces is changed without using any chemicals or mechanical equipment. It means to adjust to a predetermined state only by the function. “Humidity control or humidity control function” is used as an interior material for indoor space, etc., to reduce or keep the fluctuation of the atmospheric humidity of indoor space etc. due to temperature etc. by absorbing and dehumidifying the humidity control material. Means the nature of trying. "Chalking" refers to the phenomenon of powder adhering to the surface of a hand or article when in contact with the hand or other article. The term "atmospheric alkalinity" refers to the measurement of alkalinity (pH) from the state of discoloration of the test paper 24 hours after placing the test sample and the discoloration test paper in an atmosphere at a temperature of 30 ° C and a relative humidity of 80%. Means what you do.

Generally, in the preservation of works of art, cultural properties, ancient documents, photographic films, etc., if the atmosphere is alkaline, damage is caused by peeling or discoloration of the surface material. There is a need for a fireproof storage to prevent these and protect from fire. As is well known, in storage, it is required to always keep the stored items in the best condition, but in Japan, the stored items are stored in the best condition because of the large temperature and humidity difference between summer and winter, or day and night. For this reason, wood such as pine, cypress, and cedar has been used for a long time. However, wood has the fatal drawback of not being fire resistant. However, they are still being used because there is no alternative material.
Most recently, however, interior materials such as rock wool and gypsum board and concrete have been used only for the purpose of fire resistance. However, these refractory materials have almost no humidity control, so mechanical air conditioning is necessary.However, it is difficult to prevent the air blow from directly hitting the stored items, and the stored items may be locally dried. There is a drawback that causes adverse effects such as too much. Concrete also has a drawback that the atmosphere of the storage becomes strongly alkaline and adversely affects the storage.

The inventor of the present invention has been working on developing a material that has fire resistance and has excellent humidity control properties and an atmosphere that does not adversely affect the contents, that is, a material that can maintain the atmosphere almost neutral. Then, the surface layer of the calcium silicate molded body, which has excellent fire resistance and humidity control properties, but has the disadvantage that the chalking property and atmospheric alkalinity are alkaline, are neutralized by reacting with an acid gas, an acid or a salt thereof. Has already established a technology that can maintain the alkalinity of the atmosphere at around neutral without significantly deteriorating the excellent humidity control property of the calcium silicate molded product itself, and also significantly improve the choking resistance. (Japanese Patent Laid-Open No. 57-147424)
issue).

However, this technique also has a problem that the reforming is insufficient or that the unmodified portion is exposed due to scratches or cuts on the surface layer during construction work or the like.

Means for Solving the Problems The present inventor has conducted intensive studies to solve the above problems, and as a result, the entire formed body was modified by allowing a specific amount of gypsum to be uniformly contained in the entire calcium silicate formed body. In this condition, the alkali alkalinity of the atmosphere can be maintained almost neutral even inside the molded body without impairing the excellent humidity control property of the calcium silicate molded body itself, and the choking resistance is also improved, especially during construction work For example, it has been found that the performance does not decrease even when the surface layer is scratched or a cut surface is formed, and the present invention has been completed.

That is, the present invention is a molded article containing calcium silicate crystals and gypsum, wherein gypsum is uniformly contained in the entire molded article and the content is 5 to 20% by weight in the molded article. And a calcium silicate-based humidity control material.

In the humidity control material of the present invention, as gypsum to be contained, natural gypsum or phosphogypsum, gypsum sulfite, salt gypsum,
Any of hemihydrate or anhydrous and dihydrate gypsum such as synthetic gypsum and smelting gypsum can be used alone or in combination.
Further, the content of gypsum needs to be 5 to 20% by weight in the molded body. If it is less than 5% by weight, it is insufficient to maintain the alkalinity of the atmosphere at around neutral, and if it exceeds 20% by weight, the linear shrinkage after heating of the molded article becomes large.

In addition, as the calcium silicate crystal in the humidity control material of the present invention, zonotrite crystals, wollastonite crystals, tobermorite crystals, and the like are preferable.

Calcium silicate crystals can be produced by various known methods. For example, water can be added to a silicic acid raw material and a lime raw material to form an aqueous slurry, and the aqueous slurry can be suitably produced by a so-called stirring method or the like in which a hydrothermal synthesis reaction is performed by heating under pressure while stirring. According to this stirring method, since the obtained calcium silicate crystal takes the form of secondary particles, the strength of the molded article is increased, the humidity control is increased, and the diffusion of alkali into the atmosphere is reduced. Benefits are obtained.

As the silicic acid raw material for producing the calcium silicate crystal, any known silicic acid raw material can be used.
Examples include silica obtained by reacting hydrosilicofluoric acid by-produced in the wet phosphoric acid production process with aluminum hydroxide. Any known lime material can be used, for example, quick lime, slaked lime, carbide slag,
Cement and the like can be mentioned. These materials can be used alone or as a mixture of two or more. It is preferable to mix the silicic acid raw material and the lime raw material so that the CaO / SiO ₂ ratio (molar ratio) is usually about 0.7 to 1.3. In particular, when synthesizing tobermorite crystals, about 0.70 to 0.90 is appropriate, and when synthesizing zonotlite crystals, about 0.90 to 1.15 is appropriate.

Water is added to the silicic acid raw material and the lime raw material to prepare a raw material slurry. In the stirring method, the raw material slurry is usually subjected to a hydrothermal synthesis reaction in an autoclave with stirring as it is. The amount of water when preparing the raw material slurry is not particularly limited and may be appropriately selected, but is usually 5 times by weight or more, preferably 10 to 10 times the solid content of the raw material slurry.
It may be about 50 times by weight, and the hydrothermal synthesis reaction is usually 4 kg /
cm ² or more is preferably conducted usually about 0.5 to 20 hours under saturated steam of about 8～50Kg / cm ^2, thereby xonotlite crystals, an aqueous slurry of secondary particles of tobermorite crystals like calcium silicate crystals obtained . This crystal slurry can be dried as necessary to obtain calcium silicate crystals. In addition, wollastonite crystals are obtained by firing zonotlite crystals to about 800 to 1100 ° C.

The humidity control material of the present invention is obtained by mixing a predetermined amount of gypsum with calcium silicate crystals or an aqueous slurry thereof, adding an appropriate amount of water as necessary, molding, and drying. Ordinary additives used for calcium silicate moldings, such as fibers such as glass fibers, rock wool and asbestos, and fillers such as pulp and clay, may be added.

The molding can be performed by any of various known methods, for example, a press method, a papermaking method, etc., and the drying method is not limited at all.

Further, the humidity control material of the present invention can also be obtained by mixing a substance which reacts with calcium silicate to form gypsum to form gypsum instead of mixing gypsum in the above. Examples of the gypsum-forming substance include aluminum sulfate, diluted sulfuric acid, ammonium sulfate, and ammonium hydrogen sulfate. The compounding amount of such a substance may be an amount such that the amount of gypsum produced falls within the predetermined range of the present application. At this time, silica gel and the like are formed together with the gypsum, but they do not affect the alkalinity of the atmosphere or the humidity control property, and there is no problem.

Thus, the humidity control material of the present invention can be obtained.Furthermore, according to the method described in JP-A-57-147424, acid gas such as carbon dioxide gas and sulfurous acid gas, sulfuric acid, carbonic acid, sulfurous acid, phosphoric acid, acid such as acid, Or metal salts such as aluminum salts of these acids,
By reacting with the surface layer, the choking resistance can be further improved.

Effect of the Invention According to the humidity control material of the present invention, since the atmosphere is kept almost neutral and does not become alkaline, it is a material that has the ability to store stored items well and has excellent fire resistance. .
In particular, even when the surface layer is scratched or cut at the time of construction work, such performance is not reduced.

In the humidity control material of the present invention, by adding gypsum,
Although it is not clear why the gypsum is neutral when the gypsum is added to calcium silicate, the gypsum particles are neutral. It is considered that the alkaline portion of the atmosphere can be maintained near neutrality by suppressing the diffusion of alkali from calcium silicate into the atmosphere.

For this reason, the humidity control material of the present invention is extremely suitable for storage of storage objects, storage boxes, etc., which are troublesome when alkaline components such as art objects, cultural properties, ancient documents, photographic films, etc. come out. ,
The air conditioner has a performance that cannot be obtained, that is, the humidity can be adjusted without adversely affecting the stored items, and the stored items can be stored in the best condition.

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples. However, in the following examples, each physical property was measured by the following method.

Density and bending strength: Measured according to JIS A 9510.

Test piece pH: A sample collected from the test piece was measured as a 5% aqueous slurry with a pH meter.

Moisture absorption rate: The rate of weight increase per unit area and unit time when a sample dried at 105 ° C and placed in an atmosphere of 95% relative humidity is shown.

Dehumidification rate: The rate of weight loss per unit area and unit time of a sample in the case where the sample absorbed in the above 95% relative humidity to the equilibrium value and the drying material (CaCl ₂ ) were placed in the same atmosphere. .

Chalking: Black rubber plate 7cm long, 2cm wide, 0.3mm thick [Hardness
Using a rubber plate having a hardness of 55 by Tester Type C (manufactured by Kobunshi Keiki Co., Ltd.), the adhesion of the white powder was measured why the sample surface was light.

Surface hardness: Expressed by a pencil hardness symbol according to JIS K 5400.

Atmospheric alkalinity: The alkalinity was measured by a discoloration test paper method by the Tokyo National Research Institute for Cultural Properties, and pass / fail was determined based on the following table.

Linear shrinkage after heating: Expressed as shrinkage after holding at 1000 ° C. for 3 hours.

Example 1 A predetermined amount of dihydrate or hemihydrate gypsum, fibers and the like were added to a slurry of zonotolite crystals obtained by the stirring method, and water was added to adjust the solid content to 9.5%, followed by molding and drying. Thus, a molded body was obtained. Table 1 shows the composition of the obtained test pieces, and Table 2 shows the test results of the physical properties. In each table, N
o.1, 5, 6 and 10 are comparative specimens.

 Hereinafter,% described in the composition column indicates% by weight.

Example 2 After obtaining a gypsum-containing molded body in the same manner as in Example 1, the surface was coated with a commercially available aqueous aluminum sulfate solution (Al ₂ O ₃ content: 3%).
Was spray-coated with a solution diluted to 4 times with water, and the aqueous solution (1000 cc / m ³ ) was contained in the calcium silicate molded body, and then dried at 70 ° C. for 4 hours to further improve the choking resistance. A molded article was obtained. Table 3 shows the composition of the obtained test specimens and the results of each physical property test.

Example 3 In Example 1 No. 3, gypsum was replaced with a sulfuric acid band, a predetermined amount of fibers and the like were further blended, molded and dried to obtain a molded product. Table 4 shows the composition of the obtained test specimens and the results of physical property tests.

The gypsum content of this molded product was 7.5% by weight in the molded product.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazuhiko Kubo 4064 Kitanuma, Noda Nitta, Hozumi-cho, Motosu-gun, Gifu Prefecture Inside the Gifu Plant of Osaka Pat King Manufacturing Co., Ltd. (72) Inventor Kohei Ono Amagasaki, Hyogo Prefecture (14) Inventor Hiroshi Kaneko 62, Okamoto, Kamakura-shi, Kanagawa (56) References JP-A-57-147424 (JP, A)

Claims (1)

(57) [Claims] 1. A molded article containing calcium silicate crystals and gypsum, wherein gypsum is uniformly contained in the entire molded article and the content is 5 to 20% by weight in the molded article. Calcium silicate based humidity control material.