JPH08301644A - Gypsum-modifying agent, water-resistant gypsum composition - Google Patents

Abstract

PURPOSE: To obtain a gypsum-modifying agent, capable of improving the application workability, water resistance and mechanical properties of gypsum by dissolving a specific raw material and the copolymer of a vinylic compound with an unsaturated dicarboxylic acid anhydride in water in the presence of a water-soluble alkaline compound. CONSTITUTION: A vinylic compound is copolymerized with an unsaturated dicarboxylic acid anhydride in a molar ratio of 2:1 to 4:1 to obtain the copolymer having an acid value of 200-400. The copolymer and at least one kind of raw material, selected from a wax having a melting point of 25-150 deg.C, a paraffin having a melting point of 25-150 deg.C and a low mol.wt. hydrocarbon resin having a mol.wt. of 500-3000 are mixed in a weight ratio of 20:1 to 1:3, and subsequently dissolved in water in the presence of one or more kinds of water-soluble alkaline compounds selected from sodium hydroxide, potassium hydroxide, ammonia, ammonium hydroxide and alkanol amines.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gypsum modifier for improving water resistance and mechanical properties of gypsum and workability during construction. The gypsum obtained by the present invention is applied to products using gypsum such as gypsum board and gypsum plaster.

[0002]

2. Description of the Related Art Conventionally, gypsum has been widely used as a gypsum board or gypsum plaster in buildings and the like because it is inexpensive and has excellent fireproofing and soundproofing properties. However, in spite of these characteristics, the use is limited because of poor water resistance.

Various proposals have been made to make up for the drawbacks of such plaster. For example, one using paraffin and oxidized paraffin as a water repellent (Japanese Patent Publication No. 55-5).
0906), using wax and carboxyl group-containing wax (JP-A-55-37423), adding a protective colloid aqueous solution prepared by using monomethyl ester of styrene-maleic acid copolymer to low molecular weight polyolefin and paraffin. To be used as (Japanese Patent Publication Sho 58-5
8304 and JP-A-55-94983), those in which an aqueous protective colloid solution prepared by using an α-olefin-maleic anhydride copolymer is added to low molecular weight polyolefin and paraffin (JP-A-60-22091).
0), a mixture of a wax, a petroleum resin, an ethylene-vinyl acetate copolymer, and a vinyl compound-maleic anhydride derivative for use (JP-A-4-304268).

However, in these methods, when the gypsum product was immersed in water for a long time, sufficient water resistance could not be obtained, and the stability of the obtained emulsion was also problematic. In addition, a styrene-maleic anhydride copolymer was used for emulsion-stabilizing wax and paraffin.
The ratio of styrene-maleic anhydride copolymer in the modifier of gypsum is low, and it is necessary to force emulsify for a long time at high pressure using a high shearing force strong stirrer, piston type high pressure emulsifier, colloid mill, etc. The emulsification was extremely difficult.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks of conventional gypsum modifiers, and provides a gypsum composition which is easy to work during construction and has excellent water resistance and mechanical properties. The purpose is to

[0006]

As a result of earnest studies, the present inventors have found that (A) a specific copolymer comprising a vinyl compound and an unsaturated dicarboxylic acid anhydride, and (B) waxes,
Combining at least one kind of raw material selected from paraffins and low molecular weight hydrocarbon resins in a specific ratio,
(C) It was found that by using a gypsum modifier obtained by emulsification in the presence of a water-soluble alkaline compound, gypsum excellent in water resistance and mechanical properties can be easily obtained, and the present invention was reached. .

[0007]

That is, the present invention is a copolymer of (A) a vinyl compound and an unsaturated dicarboxylic acid anhydride and has an acid value of 200 to
400, and (B) at least one raw material selected from waxes, paraffins and low molecular weight hydrocarbon resins, the weight ratio of (A) and (B) is 20: 1.
(C) a gypsum modifier dissolved in water in the presence of a water-soluble alkaline compound, and a water-resistant gypsum composition obtained thereby.

The vinyl compound which is one component of the copolymer used in the present invention is ethylene, propylene, butene,
C2-C8 α-olefins such as isobutylene, isoamylene, and n-hexene, preferably C4-6 α
-Olefin, or styrene monomers such as styrene, α-methylstyrene, vinyltoluene, t-butylstyrene, chlorostyrene and derivatives thereof. Further, the unsaturated dicarboxylic acid or its anhydride is maleic acid, maleic anhydride, fumaric acid or the like. These monomers are polymerized under normal radical polymerization conditions.

The acid value (mg of potassium hydroxide required to neutralize 1 g of resin) of the copolymer of these vinyl compounds and unsaturated dicarboxylic acid anhydride is preferably 200 to 400. The acid value of the copolymer can be adjusted by the monomer ratio, but it may be adjusted by partial esterification or partial amidation of the carboxylic acid or partial imidation after the copolymerization. When the acid value exceeds 400, the water resistance of the obtained gypsum becomes insufficient, and when the acid value is 200 or less, it becomes difficult to obtain a uniform aqueous solution.

As the monomer copolymerizable with the above monomers, vinyl cyanide compounds such as acrylonitrile and methacrylonitrile, acrylic acid esters such as methyl acrylic acid ester, ethyl acrylic acid ester and butyl acrylic acid ester, and methyl methacrylic acid. ester,
Examples thereof include methacrylic acid esters such as ethyl methacrylic acid ester and butyl methacrylic acid ester, vinyl carboxylic acids such as acrylic acid and methacrylic acid, acrylic acid amides, methacrylic acid amides, acenaphthylene, and N-vinylcarbazole.

In the present invention, a copolymer of styrene or its derivative and maleic anhydride is preferably used. In this case, the molar ratio of styrene or its derivative constituting the copolymer to maleic anhydride is 2:
It is preferably 1 to 4: 1.

Examples of waxes and paraffins used in the present invention include paraffin wax, montan wax, oxidized paraffin, polyolefin wax, and carnauba wax. These melting points are preferably 25 to 150 ° C, more preferably 40 to 90 ° C.

On the other hand, as the low molecular weight hydrocarbon resin, carbon number of 4 to 4 obtained in the process of petrochemical industry such as naphtha decomposition is used.
Molecular weight 500 to 30 obtained by polymerizing the aliphatic or aromatic hydrocarbon fraction of 9 with a Friedel-Crafts catalyst
00 petroleum resin, coumarone-indene resin having a molecular weight of 500 to 3000 obtained by similarly polymerizing tar naphtha, asphalt, rosin, and a molecular weight of 500 to 3000.
Terpene resins, low molecular weight polyethylene having a molecular weight of 500 to 3000, polyolefins such as polypropylene, and the like. These melting points are also preferably 25 to 150 ° C, more preferably 40 to 90 ° C.

The water-soluble alkaline compound used in the present invention includes alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide, sodium carbonate,
Alkali metal carbonates such as potassium carbonate, ammonia, ammonium hydroxide, dimethylamine, trimethylamine, amines such as triethylamine, 2-aminoethanol, triethanolamine, diethanolamine,
It is selected from alkanolamines such as N, N-dimethylethanolamine, N-methyldiethanolamine and 2-amino-2-methyl-1-propanol. These may be used alone, or two or more kinds may be mixed and used. Particularly, in the present invention, alkanolamines are preferably used.

(A) A copolymer of a vinyl compound and an unsaturated dicarboxylic acid anhydride, and (B) at least one raw material selected from waxes, paraffins and low molecular weight hydrocarbon resins are (C). ) It is emulsified in water in the presence of a water-soluble alkaline compound and used as a gypsum modifier. Here, the weight ratio of (A) to (B) is preferably 100 to (A) and 5 to 300 for (B). By increasing the ratio of (A) in this way, it becomes possible to easily emulsify by using a high-strength stirrer at high temperature and high pressure without stirring, and the stability of the obtained emulsion Will also be higher. At this time, (C)
Usually, it is used in an equivalent amount to 1.1 times the equivalent amount to the carboxylic acid group of (A). The solid content concentration of the emulsion is 0.1 to 15
% By weight.

The resulting emulsion is mixed with calcined gypsum or a mixture of calcined gypsum and water and kneaded to obtain a water resistant gypsum composition (slurry). After curing, if necessary, it is dried to obtain a final gypsum product having high water resistance. At this time, the amount of the gypsum modifier used is such that the total amount of the raw materials (A) and (B) is 0.
The content is preferably 4 to 4% by weight, more preferably 0.5 to 3% by weight. If the amount of the modifier is less than this, sufficient effect of modification cannot be obtained, and if the amount is too large, the viscosity of the gypsum composition becomes high, workability may deteriorate, fire resistance and economic efficiency may be lost. There is.

If necessary, the gypsum composition may include aggregates such as perlite and vermiculite, an aggregation rate regulator,
Reinforcing fibers, foaming agents and modifiers such as cement, slag and fly ash can also be used in combination.

The present invention will be described below with reference to examples.
The present invention is not limited to the examples.

[0019]

[Examples] Table 1 shows the composition of the gypsum modifier (emulsion) and the gypsum composition, which are Examples and Comparative Examples of the present invention, and Table 2 shows the characteristics of the gypsum compositions. In the following examples and comparative examples, the obtained gypsum composition (slurry) was cast between gypsum board base papers to form gypsum boards and dried at 70 ° C. for about 2 hours. After this gypsum board was left at room temperature and a humidity of 50% for 24 hours, the water absorption and the flexural modulus were measured. The water absorption rate was calculated from the weight increase after immersion in 20 ° C. water for 24 hours. On the other hand, the curing time was determined as the time until the fluidity disappeared after the slurry was left at room temperature.

[0020]

Example 1 To 30 g of a styrene-maleic anhydride copolymer having a molar ratio of styrene and maleic anhydride of 3: 1, an acid value of 275, a melting point of 120 ° C. and a Tg of 125 ° C., 900 ml of water was added. In addition, under stirring, 13.4 g (1.02 times equivalent amount) of N, N-dimethylethanolamine (DMEA) was slowly added dropwise, and stirring was continued until a uniform aqueous solution was maintained at 70 ° C. Was cooled to room temperature and water was added to bring the total volume to 1000 ml. To 300 ml of this aqueous solution, 3 g of paraffin having a melting point of 57 ° C. was added, and using a homomixer at 70 ° C., a rotation speed of 400
Stirring was performed at 0 rpm for 30 minutes to obtain an emulsion. The average particle size was several μm and the stability was good.

150 g of this emulsion and calcined gypsum (purity 97%
250 g of the above β hemihydrate gypsum) was mixed to obtain a gypsum composition (slurry). From Table 2, it can be seen that the obtained gypsum has a low water absorption rate, an improved flexural modulus, and a good fluidity of the slurry.

[0022]

Example 2 The same styrene-maleic anhydride copolymer as in Example 1 (9.0 g), paraffin (1.0 g), and ammonium hydroxide in an amount 1.02 times that of maleic anhydride and water were mixed, Using a homomixer, the total volume was 100 ml, and the mixture was stirred at 70 ° C. at a rotation speed of 4000 rpm for 30 minutes to obtain an emulsion. This average particle size is about 10μ
m, and the stability was good.

250 g of calcined gypsum and 90 g of water as in Example 1
Was mixed, and 60 ml of the above emulsion was added thereto to obtain a gypsum composition (slurry). Also in this case, the effect of improving the water absorption and the flexural modulus was confirmed.

[0024]

Example 3 2.5 g of the same styrene-maleic anhydride copolymer as in Example 1, 7.5 g of paraffin, and 1.02 times the equivalent amount of maleic anhydride as ammonium hydroxide and water were mixed, Using a homomixer, the total volume was 100 ml, and the mixture was stirred at 70 ° C. at a rotation speed of 4000 rpm for 30 minutes to obtain an emulsion. This average particle size is about 15μ
m, and the stability was good.

250 g of calcined gypsum and 90 g of water, the same as in Example 1
Was mixed, and 60 ml of the above emulsion was added thereto to obtain a gypsum composition (slurry). Also in this case, the effect of improving the water absorption and the flexural modulus was confirmed.

[0026]

EXAMPLE 4 10 g of a styrene-maleic anhydride copolymer having a styrene / maleic anhydride molar ratio of 2: 1 and an acid value of 350, a melting point of 150 ° C. and a Tg of 124 ° C. was mixed with 900 ml of water. In addition, under stirring, 4.5 g of N, N-dimethylethanolamine (DMEA) (1.02 times equivalent amount)
Was slowly added dropwise, and stirring was continued until a uniform aqueous solution was maintained at 70 ° C. After dissolution, the aqueous solution was cooled to room temperature and water was added to make the total volume 1000 ml. To 300 ml of this aqueous solution, 1.2 g of the paraffin used in Example 1 was added, and using a homomixer at 70 ° C. and a rotation speed of 400.
Stirring was performed at 0 rpm for 30 minutes to obtain an emulsion. The average particle diameter was about 10 μm, and the stability was good.

150 g of this emulsion and calcined gypsum (purity 97%
250 g of the above β hemihydrate gypsum) was mixed to obtain a gypsum composition (slurry). From Table 2, it can be seen that the obtained gypsum has a low water absorption rate, an improved flexural modulus, and a good fluidity of the slurry.

[0028]

Example 5 Same as Example 1 except that a styrene-maleic anhydride copolymer having a molar ratio of styrene to maleic anhydride of 4: 1 and having an acid value of 215 and a Tg of 125 ° C. was used. Then, an emulsion having a solid content concentration of 4% by weight was prepared to obtain a gypsum composition having a modifier concentration of 2.0% by weight with respect to gypsum dihydrate. Also in this case, a stable emulsion was obtained, and the effect of improving the water absorption rate and the flexural modulus was recognized in the gypsum composition.

[0029]

Example 6 As in Example 1, except that potassium hydroxide was used as the alkaline compound, the solid content concentration was 8% by weight.
3. An emulsion was prepared and the concentration of the modifier for dihydrate gypsum was 4.
A gypsum composition of 0% by weight was obtained. Also in this case, a stable emulsion was obtained, and the fluidity of the gypsum slurry was slightly lowered,
Improvement effects were observed in the water absorption rate and bending elastic modulus of the obtained gypsum composition

[0030]

Comparative Example 1 The characteristics of gypsum alone were measured without using an initiator.

[0031]

Comparative Example 2 A styrene-maleic anhydride copolymer having a molar ratio of styrene to maleic anhydride of 1: 1 and an acid value of 480, a melting point of 160 ° C. and a Tg of 154 ° C. was used. An emulsified liquid of a modifier was prepared in the same manner as in Example 1 to obtain a gypsum composition having a total modifier concentration of 2.0% by weight with respect to the finally obtained gypsum composition. This gypsum composition is
The gypsum board was not able to be prepared because it did not harden even when left standing.

[0032]

Comparative Example 3 Same as Example 1 except that a styrene-maleic anhydride copolymer having a molar ratio of styrene to maleic anhydride of 5: 1, an acid value of 180 and a Tg of 125 ° C. was used. In addition, when an attempt was made to prepare an emulsion having a solid content concentration of 4% by weight using DMEA in an amount equal to that of the maleic anhydride group, a stable emulsion was not obtained.

[0033]

Comparative Example 4 An emulsion having a solid content of 10% by weight was prepared in the same manner as in Example 2 except that the same styrene-maleic anhydride copolymer as in Example 1 was 1.0 g and paraffin was 9.0 g. However, no stable emulsion was obtained.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

According to the present invention, compared with the case of using a conventional water repellent emulsion composition, it is possible to improve the water resistance and mechanical properties of gypsum by a simple operation without requiring a special emulsifying device. Became possible. The gypsum board obtained using the gypsum modifier of the present invention can be expected to be used in places where water is used, such as a bathroom, a washroom, and a kitchen.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C09K 3/18 101 C09K 3/18 101 // (C04B 28/14 24:26 24:00) ( 72) Inventor Yoshiyuki Miyaki, 1 Awata-cho, Chuodo-ji, Shimogyo-ku, Kyoto, Japan Elf Atchem Japan Co., Ltd. Kyoto Technical Center

Claims (8)

[Claims] 1. A copolymer of (A) a vinyl compound and an unsaturated dicarboxylic acid anhydride having an acid value of 200 to 400,
And (B) at least one raw material selected from waxes, paraffins and low molecular weight hydrocarbon resins,
A gypsum modifier which is emulsified in water in the presence of (C) a water-soluble alkaline compound so that the weight ratio of (A) and (B) is 20: 1 to 1: 3. 2. The gypsum modified according to claim 1, wherein the copolymer is composed of styrene or its derivative and maleic anhydride, and the molar ratio of styrene or its derivative and maleic anhydride is 2: 1 to 4: 1. Pledget. 3. The water-soluble alkaline compound is selected from sodium hydroxide, potassium hydroxide, ammonia, ammonium hydroxide, and alkanolamines.
The gypsum modifier according to claim 1, which is a compound of at least one kind. 4. An alkanolamine is selected from 2-aminoethanol, triethanolamine, diethanolamine, N, N-dimethylethanolamine, N-methyldiethanolamine, 2-amino-2-methyl-1-propanol. The gypsum modifier according to claim 3, which is a compound of at least one kind. 5. A copolymer of a vinyl compound and an unsaturated dicarboxylic acid anhydride having an acid value of 200 to 400, and at least one selected from (B) waxes, paraffins and low molecular weight hydrocarbon resins. Gypsum modifier and gypsum which are dissolved in water in the presence of a water-soluble alkaline compound so that the weight ratio of (A) and (B) is 20: 1 to 1: 3 A water-resistant gypsum composition, which comprises 0.4 to 4% by weight of the total amount of (A) and (B) with respect to gypsum. 6. The water resistance according to claim 5, wherein the copolymer is composed of styrene or its derivative and maleic anhydride, and the molar ratio of styrene or its derivative and maleic anhydride is 2: 1 to 4: 1. Gypsum composition. 7. The water-soluble alkaline compound is selected from sodium hydroxide, potassium hydroxide, ammonia, ammonium hydroxide, and alkanolamines.
The water-resistant gypsum composition according to claim 6, which is a compound of at least one kind. 8. The alkanolamines are selected from 2-aminoethanol, triethanolamine, diethanolamine, N, N-dimethylethanolamine, N-methyldiethanolamine, 2-amino-2-methyl-1-propanol. The water-resistant gypsum composition according to claim 7, which is one or more kinds of compounds.