JPS60171261A - Manufacture of incombustible gypsum 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] The present invention relates to a method for manufacturing noncombustible gypsum board.

More specifically, a mixture of a predetermined amount of fibers, a set retarder, and the required amount of water is molded into a powdered gypsum of 50 to 85 parts by weight of wettable gypsum and 50 parts by weight of industrial water gypsum, hardened, and dried. The present invention relates to a method of manufacturing a chain plate.

Among inorganic noncombustible building materials, gypsum board is widely used as an interior material because it is economically usable and has excellent fire resistance, sound insulation, heat insulation, dimensional stability, and workability. . The basic gypsum board manufacturing technology is to add water to calcined gypsum, which is made by heating and dehydrating engineered water gypsum, and then forming and hardening it to obtain a plate-like product of a predetermined shape. Therefore, as a general rule, industrial water gypsum, which does not have hardening properties as plaster, cannot be used. If even a few percent of industrial water gypsum is mixed into the calcined gypsum, the strength of the molded product will not only decrease significantly, but also paper ( = In the case of J type gypsum board, the adhesion with paper is also lost.
The mixed use of calcined gypsum and industrial gypsum was denied, as it promoted the setting of hemp, so the amount of setting retardant was increased to alleviate the effect.

(Special Publication No. 57-49004). Therefore, if powdered gypsum equivalent to known stone and sawn board could be produced by replacing a considerable proportion of calcined gypsum with industrial water gypsum, then It becomes possible to save a huge amount of thermal energy for producing calcined gypsum.

On the other hand, there are also several proposals regarding gypsum boards and methods for manufacturing the same, which do not use calcined gypsum but instead use industrial gypsum to form and harden. However, they are, for example, ■300k
Even though extremely high pressure such as g/cm' or more is required, the bending strength of the resulting gypsum board is 10 to 35 kg/cm.
(Japanese Patent Publication No. 48-31012) or ■Comparatively low pressure of 10 to 250 kg/cm.
It is extremely low at only about 5 to 30 kg/am''2 (Special Publication No. 55-348), and only a few have been obtained for practical use as building materials.

The present inventors have solved the problems related to the above-mentioned known technologies, namely, achieved energy saving in terms of raw materials by using industrial gypsum in the production of gypsum boards, eased the manufacturing conditions for products using industrial gypsum, and We conducted extensive research on improving strength. As a result, it was surprisingly found that 5 to 50 parts by weight of industrial water gypsum was used in the powdered gypsum used for fiber-filled gypsum boards, and the remaining 85 parts by weight
It has been found that when using ~50 parts by weight of calcined gypsum, the practical strength of the gypsum board is as good as that using 100% calcined gypsum, and the manufacturing process can be carried out more smoothly and efficiently, The present invention was completed based on this knowledge.

As is clear from the above description, the purpose of the present invention is to provide a new method for manufacturing gypsum board, and more specifically, it is possible to use both calcined gypsum and engineered water gypsum as raw material gypsum powder, and the manufacturing method The object of the present invention is to provide a manufacturing method that is smooth, efficient, and has a strength that can be used for practical purposes.

The present invention has the following main configurations.

0.5-30 parts by weight for 100 parts by weight of powdered gypsum consisting of 50-95 parts by weight of wettable gypsum and 5-50 parts by weight of Futari gypsum.
Fiber in weight part, 0.1 to 2.0% by weight based on the hydrated gypsum
1. A method for producing a noncombustible gypsum board, which comprises forming a mixture of a set retarder and water before the hydrated gypsum is hydrated, and hardening and drying the mixture.

The structure and effects of the present invention will be explained in detail below.

The raw material characteristic of the method of the present invention is that hydratable gypsum and water gypsum are substantially used together. The hydratable gypsum used is α, which is obtained by heat-treating industrial water gypsum using a known method.
It is any one of type hemihydrate gypsum, β type hemihydrate gypsum, and soluble anhydrite, or a mixture of two or more types. The fineness of the hydrated gypsum used is preferably 5000 cm'/g or less in Blaine specific surface area value.

A fineness of fineness which significantly exceeds this value tends to disadvantageously shorten the curing time of molded articles from the above-mentioned mixtures according to the invention, and in order to rectify this the addition of set retarder may be necessary. Increased and undesirable.

On the other hand, if the fineness is too coarse, the strength of the resulting cured product, that is, the gypsum board, will decrease. Therefore, the fineness is preferably 500 g or less as the maximum particle size, and the Blaine specific surface area value is preferably 1000 cm'/g or more. In addition, when employ|adopting the paper-making method as a shaping|molding method based on this invention, it is preferable that this specific surface area value is 5000 ctn'/g or less. This is because it becomes possible to minimize the loss of the used hydrated gypsum powder into the filtrate.

On the other hand, as for water gypsum, as long as its particle size is 500# or less, its source or manufacturing method does not matter. As is well known, industrial water gypsum, which is used as an industrial raw material, includes many types of chemical industrial (by-product) products in addition to natural products. Bulky products such as natural gypsum must be ground to the above-mentioned particle size, and other chemical gypsums are easier to use in this respect. On the other hand, the industrial water gypsum is
Hydrateable gypsum (
significantly accelerates the setting of gypsum hemihydrate and/or soluble anhydrite). The disadvantage is that in order to prevent this, the amount of set retarder to be added to the formulation for making gypsum board must be increased. Therefore, the fineness of the industrial water gypsum is
It is preferable that the plane specific surface area value is 5000 crrf/g or less. Before use, it is preferable that the gypsum be mixed and dispersed during disintegration of the fibers.

The usage ratio of the above-mentioned hydratable gypsum and industrial water gypsum is the total amount of both 10 (1 part by weight, 50 to 95 parts by weight of the former,
The latter is 5 to 50 parts by weight. If the former is less than 50 parts by weight, the strength of the molded article will be insufficient, and if it exceeds 85 parts by weight, it will go against the purpose of the present invention, which is to save hydrated gypsum. On the other hand,
When the latter is added in an amount of 50 parts by weight or more, the strength of the molded product is significantly reduced, and the practicality of the final gypsum board is lost. The table below shows an example of the relationship between the mixing ratio of industrial gypsum and the strength of gypsum board.

Table Dihydrite: ゛Mud - χ and gypsum & strength (kg/c
The fibers used in the present invention are, for example, inorganic fibers such as asbestos or glass fibers, or natural or synthetic organic fibers such as cell-A's fibers, vinylon fibers, polypropylene fibers, or polyamide fibers. One type or a combination of two or more types can be used.Among these, asbestos fiber and cellulose M11 are especially suitable for use in gypsum (hardened product).
It is preferable to use one or a mixture of these in the fibers used because of their strong adhesive strength.

Incorporating the above-mentioned fibers into the mixture for producing gypsum board according to the present invention improves the brittleness of the resulting hardened gypsum body, and also improves impact strength and bending strength, and improves flexibility. make it good. The amount of fiber used in the mixture is preferably 0.5 to 30 parts by weight per 100 parts by weight of powdered gypsum. If it is less than 0.5 parts by weight, the above-mentioned effects are insufficiently expressed, and even if it exceeds 30 parts by weight, the effects will not improve and it is not economical. On the other hand, some physical properties may deteriorate.

The amount of water used in the above-mentioned mixture according to the invention is not limited and varies depending on the forming method. However, by mixing 15 to 2.500% by weight based on the amount of the mixture other than humans, the mixture can be easily molded. The minimum amount of water required is the amount of water required for the hydratable gypsum to be completely hydrated.

As the gypsum setting retarder used in the present invention, any of known substances such as glycerin, alcohol, phosphate, carboxylic acid, oxycarboxylic acid or their salts, and amino acid derivatives can be used. However, when a large amount of industrial water gypsum (5 to 50 parts by weight) is actively blended into 100 parts by weight of powdered gypsum as in the present invention, especially when a small amount of 41 is added, solidification occurs. It is necessary to satisfy the conditions that the retardation effect is large and (1) the strength of the obtained stone/g hardened body is not reduced. From the above viewpoint, the best spreading agent found by the present inventors is a combination of tartaric acid or a metal salt thereof, or more preferably one or more thereof, and a 7 min. rust conductor. The metal of the metal salt layer is preferably an alkali metal.

The amount of the setting retarder to be used varies depending on the method of forming the gypsum board that is the object of the method of the present invention, but it is typically 0.1 to 2 parts by weight per 100 parts by weight of the wettable gypsum used. I need. (Less than 1.1 parts by weight.

If the amount exceeds 2 parts by weight, the setting retardation effect cannot be expressed, and the strength of the stone/a hardened body is reduced.

In the present invention, the pH of the mixture or slurry obtained by mixing the above raw materials is preferably adjusted to 7 or higher. The preparation method may be a method of using a small amount of a basic substance such as cement slaked lime as an additive in the mixture. Such PH adjustment not only enhances the effect of the curing retarder and prevents the formation of rust or scale on the gypsum board manufacturing equipment according to the present invention, but also prevents the production of nails on the product gypsum board during use. It has effects such as rust prevention.

As a molding method for manufacturing a gypsum board using the mixture according to the present invention manufactured as described above, any known molding method such as pouring, dehydration, pressure compression, or paper forming can be used. However, whichever molding method is employed, the molding must be performed before the hydrated gypsum in the mixture is hydrated. If molding is performed after the hydrated gypsum in the mixture has been hydrated, the strength of the resulting hardened gypsum product will be drastically reduced, making it impossible to obtain a gypsum board that maintains practical strength. For the same reason, if a pressurization process is included as part of the molding process, the process must be completed before the water-friendly gypsum in the raw material mixture is hydrated. The pressure at the time of pressurization needs to be 10 to 500 Kg/Cm'. 50 Kg especially for the aforementioned mixture according to the invention.
/crn' or higher compression molded gypsum board has almost no strength compared to that obtained using only hydrated gypsum as powdered gypsum, even though it contains industrial gypsum. You can get something just as good. After hydration is complete, the formed plasterboard is allowed to dry. Drying may be carried out by a known method under appropriate conditions.

As described above, a gypsum board according to the present invention is obtained,
The effluent mixture generated during the manufacturing process can be recycled and used as is. In addition, morphologically defective products of gypsum boards produced by the method of the present invention, or recovered products such as cut ends during shaping, can be re-pulverized and reused as the raw material industrial water gypsum and part of the fibers. The reason why these recycled or recovered materials are possible is that even if the hydratable gypsum in these reused raw materials hydrates and turns into industrial gypsum, it cannot be treated as raw material industrial gypsum and used in the present invention. This is because the mixing ratio of such raw materials can be adjusted, and this can be said to be an effect that cannot be predicted from the conventional method in which only hydrated gypsum is used as powdered gypsum. In the case of reuse as described above, it goes without saying that the proportion of industrial water gypsum in the total raw materials must not exceed 50% of the powdered gypsum. By stacking a plurality of plates and press-molding them, an integrated thick gypsum board of any thickness can be manufactured.

In the method of the present invention, various known additives can be used to improve various physical properties of the target gypsum board. These include, for example, walrus night, mica, vermiculite, diatomaceous earth, and lt perlite, but are of course not limited to these. The amount of these minerals added is
It is desirable that the amount of ML used in the raw material Jt compound according to the present invention is determined within the framework of the amount used, that is, the total amount of the fibrous and mineral substances is 0.000 parts by weight per 100 parts by weight of powdered gypsum.
Good results are obtained when used within the range of 5 to 30 m.

The method of the present invention is economical because it is not necessary to use only the expensive hydrating face/g as the raw material powder stone/R, and up to half of the amount of inexpensive industrial water gypsum can be used in combination. Furthermore, the method of the present invention can be advantageously implemented particularly when applied to a papermaking method for the following reasons. That is, (1) the filterability of the slurry is improved, so the papermaking properties are improved; (2) it is not necessarily necessary to use asbestos and pulp together as the m-fibers used; This is based on the mixed use of industrial water gypsum as powdered gypsum.
. In addition, (1) there is no need to increase the amount of setting retardant (compared to the case where industrial gypsum is not blended) for stable continuous operation when white water and running water gypsum are used in circulation. ZARANI ■ When tartaric acid or its metal salt and an amino acid derivative (for example, commercially available product name Baftat) are combined as the retardant, the amount of retardant added is smaller than when tartaric acid or its metal salt is used alone. 1. Due to the pressure forming after papermaking according to the method of the present invention, most of the amino acid derivatives contained before forming are transferred into the filtrate, promoting the hydration effect of the paper product, and achieving high strength in a short period of time. / Stones and a-boards are obtained.

In addition, the strength of the gypsum board produced by the method of the present invention was significantly lower than that of the conventional gypsum board manufactured with only a few percent of industrial water gypsum mixed in, compared to the case where the gypsum board was not mixed. Therefore, there is an advantage that even if double gypsum is used for half of the gypsum raw material, the strength decreases only slightly. Furthermore, the gypsum board produced by the method of the present invention has a higher fire resistance than conventional products.
Not only is it water resistant, but it also has various physical properties as an interior material, such as bending strength, impact resistance, dimensional stability, and flexibility.

It also has better workability, nail retention, etc.

Examples and comparative examples using papermaking methods and other manufacturing methods are shown below. The following methods were adopted as testing methods for these.

Bending strength: JISA 5418 (asbestos cement calcium silicate board) Impact strength: JISC: 2210 (asbestos cement board for electrical insulation) Dimensional change rate: JISA 541B (length change rate due to water absorption) Heating shrinkage rate: JISA 9510 (silicic acid Calcium insulation material). However, the heating conditions are 850°C for 2 hours, non-flammable: Ministry of Construction Notification No. 1828 Examples 1 to 9. Comparative Examples 1 to 6 The following raw materials were mixed in the proportions shown in Table 1 below.

Exhaust gypsum: Industrial gypsum produced as a by-product of the flue gas desulfurization method (particle size: 0
．． 511m/m sieve all through, Brain 1200 crn'
/g) Phosphate gypsum Diphosphogypsum (particle size is 0.59mar
S sieve all through, Brain 900crn'/g) β-type hemihydrate gypsum: Plaster of Paris, commercially available α-type hemihydrate gypsum: α-gypsum for molding, commercially available Asbestos: Amoysite asbestos crushed with a pan-shaped grinder Waste paper: waste newspaper Pulp crow fiber: E-glass cut product, length 172 inches Slaked lime: Commercial product Tartar sauce: Commercial product Amino acid derivative: Pufftard 5-02 (manufactured by Ajinomoto ■)
The method of mixing the above raw materials is to use only tartaric acid and amino acid derivatives, which are setting retardants, at the outside weight percent relative to the hydrated gypsum, β-type hemihydrate gypsum or α-type hemihydrate gypsum. Parts by weight (same as % by weight).

The mixing order is as follows: A predetermined amount of asbestos, waste paper or glass fiber Mt.
A predetermined amount of β-type hemihydrate gypsum or α-type hemihydrate gypsum is added to a slurry of water mixed with fibers, slaked lime, industrial gypsum, tartaric acid, and amino acid derivatives.

The amount of water was adjusted so that the total solid concentration was 10% by weight in the step no.

The slurry thus obtained is scooped up using a rotary round net cylinder and taken up with the top layer of an endless ferret to form a thin film.The slurry is then dehydrated using a dewatering device with a suction force of 18 to 10 mmHg, and then made. The material was laminated on a roll until it reached the target finished thickness of 6 mm and was cut using a force machine to obtain a green sheet.

Since the calcined gypsum contained in the raw sheet thus obtained is hydrated, 1. This was pressurized and dehydrated using a predetermined pressure tube J, and the amount of pressurized and dehydrated was hardened and dried to obtain a gypsum gypsum board according to the method of the present invention or as a comparative example. In addition, as a comparative example, the same procedure was carried out except that no industrial water gypsum was added.

The product gypsum board obtained as described above was subjected to various surface tests and the results are shown in Table 2.

Table-I J! 1. Table 2 Gypsum board physical properties Examples 10 to 18. Comparative Examples 7 to 12 Using the same raw materials as those used in Examples 1 to 9, the following coatings were prepared. 3, and add 10 times the weight of water to the mixture, i.e., the solid content, to form a slurry, pour the slurry onto a slip paper to spread it to a uniform thickness, and after dehydration by suction, the results are shown in the same table. A gypsum board was obtained by pressure molding and subsequent curing and drying, and its bulk specific gravity and bending strength were measured.

The results are shown in the same table.

Table 3 Raw material blending ratio, molding pressure (■) and results Note 1 kg/cnf, tl kg/crn' Example 18 (Filterability of mixtures related to the present invention) Wood pulp (softwood) was used as a disc-shaped rear liner. using Canadian Standard Freeness (GSF) values of 50, 200, 400 and 7.
Fibrillation was carried out in 4 stages of 00cc. Water is added to a mixture of 5 g of these four types of samples and 45 g of calcined gypsum, or 22.5 g of calcined gypsum and 22.5 g each of flue gas devalued gypsum, the total volume is adjusted to 1 volume, and the mixture is stirred to form a slurry. And so.

These slurries were individually measured at 45 mes using a C3F measuring device.
The water was poured onto a mesh screen, and the filtrate was collected for 30 seconds from the time of injection. The volume of this filtrate was measured and shown in Table 5 below. Subsequently, the dry weight of the powder solid content in each filtrate was measured and shown in Table 6 as the amount of powder loss.

Table-5417 Water volume measurement results (filtered water is 11cc in the table) As shown in Table-5, in the case of the same -C5F value, dihydrate/g
The drainage amount of slurry mixed with gypsum is significantly larger than that of calcined gypsum alone.

Table 6fa Measurement results of the amount of powder loss flowing out in ice water (the dry amount J1g in the table) The amount of loss is significantly smaller than that of calcined gypsum alone.

Applicant for the watch Onoda Cement Co., Ltd. Same as above Patent attorney for Asahi Asbestos Industries Co., Ltd. Katsuhiko Nonaka Procedural amendment March 1980, ? Day 1, Indication of the case 1982 Patent Order No. 25587 2, Name of the invention Method for manufacturing non-combustible gypsum board 3, Person making the amendment Relationship to the case Patent applicant mountain 6276 Oaza Onoda, Ono FrJ City, Prefecture 1 (024
) Onoda Cement Co., Ltd. 4, Agent 4-4-15 Tsukiji, Chuo-ku, Tokyo (104) 6, No number of inventions increased by amendment 7, “Detailed description of the invention” in the specification to be amended column.

8. Contents of amendment The specification shall be amended as follows.

(1) On page 8, line 144 from the bottom, ``The fiber used is'' is corrected to [The fiber used is J.

(2) r next to “cement” in the 6th line from the bottom of page i1o
, insert J.

``') @+3, page 3, line 3, ``Wollast Night'' is corrected to ``Wollast Night.''

(4) F Nohelite J on the 5th line of the same page is “Pearlite”
Correct.

(5) In the 6th line from the bottom of the same page, "Mota," is corrected to "Also."

(8) On page 17, line 6, ``Sasetomono'' is corrected to ``Sasetamono''.

(7) In the fifth line from the bottom of the same page, "gypsum gypsum" is corrected to "gypsum."

(8) In the fourth or third line from the bottom of the same page, "Except not added" should be corrected to "Except not added or used at least 50% by weight."

(9) On the second line from the bottom of the same page, insert "r" after "on the plasterboard."

(10) In Table 1 on page 18, in the column below the column for “type of gypsum,” “α-type hemihydrate” is changed to “β-type hemihydrate,” and “β-type hemihydrate” is changed to α
Corrected to ``Kata Hansui''.

(11) Last line of Table 2 on page 18 (note r // 6
R O, 0!5J in the "Dimensional change rate %" column in row J)
Similarly, insert r3.2 J in the "heat shrinkage percentage" column.

that's all

Claims (7)

[Claims] (1) 50 to 85 parts by weight of hydrated gypsum and 5 to 50 parts by weight of industrial water gypsum
0.5 parts by weight for 100 parts by weight of powdered gypsum
~30 parts by weight of fiber, 0.1-2.
4. Forming a mixture of 0% by weight of a set retarder and water before the hydration stone is hydrated and allowing it to harden and dry. Manufacturing method of non-combustible surface/a-board marked as ¥. (2) The method according to claim (1), which uses asbestos fibers, cellulose fibers, or a combination thereof. (3) The method according to claim (1), wherein tartaric acid or a metal salt thereof is used as the setting retarder. (4) The method according to claim (1), wherein the pH of a mixture consisting of hydrated gypsum, dihydrate-*, tam, a setting retarder, and water is adjusted to 7 or more. (5) Iθ~500kg/crn' of the mixture during molding
The method according to claim (1), which comprises press molding at a pressure of . (6) The method according to claim (1), wherein the method is formed by a circular mesh papermaking method. (7) Raw sheet Tk after papermaking 10-500kg/cr
Claim No. 6: Pressure molding is performed at a pressure of n'.
The method described in section.