JPH01122953A - Formed calcium silicate - Google Patents

Abstract

PURPOSE:To obtain a formed article having excellent mechanical strength and heat-insulation property as well as hydrophobicity, by adding an acrylstyrene emulsion, starch and water to hydrated calcium silicate, forming the obtained aqueous slurry and drying the product. CONSTITUTION:The objective formed calcium silicate is produced by forming an aqueous slurry composed of 100pts.wt. of hydrated calcium silicate, 5-30pts. wt. (solid basis) of an acrylstyrene emulsion, 0.5-15pts.wt. of starch and a proper amount of water and drying the formed product. The acrylstyrene emulsion used in the above process is preferably the one obtained by copolymerizing a monomer mixture containing 1-30wt.% (solid basis) of a monomer having carboxyl group with a monomer forming a base of the acrylstyrene emulsion. A monomer having phosphoric acid group or sulfonic acid group may be used in place of the monomer having carboxyl group.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a calcium silicate molded article, particularly a vine calcium silicate molded article that has excellent mechanical strength and heat insulation properties and is hydrophobic.

[Prior Art] Calcium silicate molded bodies are lightweight and have heat insulating properties, so they are finding use in various heat insulating materials and building materials.

However, such materials generally have the drawback of insufficient mechanical strength, and as a means to improve this, a method of adding polymers, etc. has been proposed (Japanese Patent Application Laid-Open No.
4-160428 and 60-246251). In addition, a calcium silicate molded body with excellent water resistance has been proposed by imparting hydrophobicity to the polymer (Japanese Patent Application Laid-Open No. 1983-1999).
(See No. 17462, Clothes).

[Problems to be Solved by the Invention] However, the former two inventions have drawbacks in that they are still insufficient in terms of heat insulation and strength when considering their use as building materials. In addition, in the latter invention, the so-called attractive properties of the emulsion and calcium silicate are not considered because the monomer is too fixated on hydrophobicity, and therefore, the strength is low considering the amount added, and the nonflammability is low. However, there are drawbacks such as no consideration given to

On the other hand, all of the above inventions have a bulk density of 0.2 to
It is relatively large at 1.0 g/cm' and has a low bulk density (0,1
3 g/cm') is not intended.

When calcium silicate is used as a heat insulating material, one having a bulk density of 0.13 g/cm3 or less is used, but none of the above inventions is applicable to this use.

Furthermore, even with currently commercially available calcium silicate insulation materials, the bulk density is 0.13 g/cm'' according to the JIS standard.
Hereinafter, although the thermal conductivity is specified as 0.042 and cal/m-h-'IC or less, the actual bulk density is 0.042.
13-0.15 g/cm", thermal conductivity 0.042-0
, 047 cat/mh・℃, which is outside the standard.

In addition, the thermal conductivity is 0.04 at a heat resistance temperature of 1000°C.
All low-cost materials for furnace materials and boiler insulation materials that require 5 cal/m-h/cii after FI are 51
It is no exaggeration to say that it was 1.

[Means for Solving the Problems] The present inventor actually imparts sufficient lightness and heat resistance to calcium silicate, which inherently has lightness and heat resistance, and
Furthermore, the aim was to find a calcium silicate molded body that could also have hydrophobicity [as a result of various research and examinations,
It has been found that the above object can be achieved by preparing a slurry in which specific amounts of a specific emulsion and starch are added to calcium silicate hydrate, and molding and drying the slurry. Thus, the present invention provides calcium silicate hydrate 10
0 parts by weight, an aqueous slurry consisting of 5 to 30 parts by weight of an acrylic styrene emulsion in terms of solid content, 0.5 to 15 parts by weight of starch, and water is molded and dried. is to provide.

Calcium silicate hydrate used in the present invention can be obtained, for example, by hydrothermally synthesizing calcareous raw materials such as quicklime and slaked lime and silicic raw materials such as silica sand and fly ash. The length of is 0.3
Preferably, spherical secondary particles are composed of t1i crystals of calcium silicate with a diameter of about 3μ and have a diameter of about 10 to 100μ,
-Crystals commonly called xonotrite and tobermorite,
Particularly preferred is xonotlite.

Typical examples of such calcium silicate and its manufacturing method are described in detail in Japanese Patent Publication No. 45-25771.

The calcium silicate hydrate used in the present invention can be used in the form of a slurry after hydrothermal synthesis, or by dehydrating and drying the slurry and adding the wetted water.

Next, the acrylic styrene emulsion used in the present invention contains 1 to 30% by weight of 1 to 30% by weight of 1 to 30% by weight of carboxyl group-containing 1 to 3. Those obtained by copolymerization are preferred.

Furthermore, in place of the chemical compound having a carboxyl group, a chemical compound having a phosphoric acid group or a sulfonic acid group may be used in the same manner.

It is presumed that when monomers having these strong acid groups are used, some of the calcium in the calcium silicate forms a strong acid salt, which strengthens the bond with the calcium silicate.

Examples of the monomer having a carboxyl group include unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid, and unsaturated dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid. In addition, examples of monomers having a phosphoric acid group include 2-methacrylic-ethane phosphoric acid, 2-acrylic-ethane phosphoric acid, and 2-acrylic acid.
Examples of ethanephosphoric acid having a sulfonic acid group include styrenesulfonic acid and 2-acrylamido-2methylpropanesulfonic acid.

On the other hand, examples of base materials for acrylic styrene emulsions include acrylic esters such as methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, and methacrylate. butyl methacrylate, Nisder methacrylates such as 2-ethylhexyl methacrylate,
Examples include aromatic vinyls such as styrene, a-methylstyrene, and chlorostyrene.

When copolymerizing the above monomer having a strong acid group such as a carboxyl group with the monomer that becomes the base of the acrylic styrene emulsion, the proportion of each monomer used is as follows:
It is appropriate to use 1 to 30% by weight of the former and 70 to 99% by weight of the latter.

The base of the acrylic styrene emulsion is 30% of the above acrylic acid or methacrylic acid ester monomer based on the entire aqueous emulsion polymer emulsion.
~94% by weight, styrenic intermediate 5-69'iM H
, t% is preferred.

If the ratio during copolymerization deviates from the range described in +lii,
If the former is less than 1%, the binding concentration with calcium in calcium silicate will be low, so the strength improvement effect of the molded product will be small, and if it is more than 30%, it will become unstable when mixed with calcium silicate hydrate particles. This is not preferable since there is a possibility that a gelled product may be formed.

The glass transition temperature of the copolymer constituting the acrylic styrene emulsion is preferably between -30°C and +30°C. If the glass transition temperature is less than 130°C, the reaction between the copolymer and Ca in the calcium silicate will be insufficient, and the effect of improving the strength of the molded article will be small. Furthermore, if the glass transition temperature exceeds +30° C., the copolymer will deteriorate in temperature, and no improvement in the strength of the molded product can be expected.

In addition, in the present invention, the glass transition point (Tg
) can be derived using the approximate formula shown below.

I/Tg = Wl/TI +W2/Tl +Wl/T3
--Tg: Glass transition temperature (absolute temperature) of copolymer W + , W 2. W3; Weight % of specific monomer in copolymer T1. T2. T, ; Glass transition temperature (absolute temperature) of a homopolymer made of the monomer Polymerization example 1 200 parts of deionized water was charged into a reaction vessel equipped with a stirring device, a reflux condenser, a dropping funnel, and a thermometer, and nitrogen gas was added. Replaced with. Next, while adjusting the temperature inside the reaction vessel to 60°C and stirring, an emulsified solution of Iij 771 having the following composition, a solution of 1 part potassium persulfate dissolved in 50 parts of deionized water, and 1 part of sodium hyposulfite dissolved in 50 parts of deionized water was added dropwise over 3 hours to polymerize.

Neogen R (Anionic emulsifier manufactured by Dai-Kogyo Seiyaku) 5 parts Emulgen 950 (Nonionic emulsifier manufactured by Kao Atlas Co., Ltd.) 5 parts Deionized water 200 parts 2 Edylhexyl acrylate 220 parts Styrene
26 parts 5 parts acrylic acid
15 parts During this time, the temperature inside the container was kept at 60℃±2℃, and the temperature was kept at the same temperature for 1 hour, then cooled to 30℃.
When the amount is below, add 28% ammonia water to 7 pl+.
After adjusting to ~9, it was filtered. The copolymer produced had a glass transition temperature of 17°C. Ex this emulsion
, l.

Polymerization Example 2 A copolymer was obtained in exactly the same manner as in Polymerization Example 1, except that the composition of the monomer emulsion solution shown in Polymerization Example 1 was changed to the composition shown below. The glass transition temperature of the copolymer produced was -12°C.

Neogen 1′? (Anionic emulsifier manufactured by Dai-Kogyo Seiyaku) 5 parts Emulgen 950 (nonionic emulsifier manufactured by Kao Atlas Co., Ltd.) 5 parts Deionized water 200 parts 2-ethylhexyl acrylate 235 parts Styrene
255 parts itaconic acid
10 parts Let this emulsion be EX, 2.

Polymerization Example 3 A copolymer was obtained in exactly the same manner as in Polymerization Example 1, except that the composition of the monomer emulsion solution shown in Polymerization Example 1 was changed to the composition shown below.

The glass transition temperature of the produced copolymer was -10°C.

Neogen R (anionic emulsifier manufactured by Dai-Kogyo Seiyaku) 5 parts Emulgen 950 (nonionic emulsifier manufactured by Kao Atlas Co., Ltd.) 5 parts deionized water 200 parts n-butyl acrylate 285 parts styrene
190 parts methacrylic acid
25 parts Let this emulsion be Ex, 3.

Next, the starch used in the present invention has the role of adhering the calcium silicate permanent particles and the acrylic styrene emulsion to each other, and the surface of the calcium silicate hydrate generally has a negative (jF) charge. Therefore, cationic starch is preferable.

Such cationic starches include, for example, carboxyalkyl starch, hydroxyalkyl starch, cyanoethyl starch, allyl starch, benzyl starch, vinyl starch, carbamyl edyl starch, dialkylaminoalkyl starch, etherified starch, or phosphate starch, fatty starch. Examples include esterified starches such as acid starches. In particular, dialkylaminoalkyl starch is preferred because it has relatively high cationicity.

Although the amount of starch to be used is strictly determined by the type of emulsion used, it is generally appropriate to use 0.5 to 15 parts by weight per 100 parts of the solid content of calcium silicate hydrate.

These are mixed to form an aqueous slurry, and the appropriate solid concentration of the slurry is usually 20% by weight or less, but considering moldability etc., it is recommended to use about 5 to 10 parts by weight. preferable.

Furthermore, in the present invention, it is effective to add a water repellent at the time of preparing the raw materials in order to reduce the wet-dry shrinkage of the calcium silicate molded body. The water repellent used is preferably a silicone-based, paraffin-based, wax-based water repellent, or the like. If the amount of water repellent used is large, the water repellency will improve, but there is a risk of inconveniences such as a decrease in non-flammability and difficulty in painting, so generally it is 0.1 to 3 weight based on the total solid content. It is appropriate to adopt approximately %.

Further, in the present invention, cement is used in the calcium silicate molded body so that it retains its shape when dried. As such cement, Portland cement, alumina cement, silica cement, etc. are used, but it is preferable to use Portland cement. The appropriate amount of cement to be used is 1 to 20% by weight based on the solid content of calcium silicate. Use: 1 layer of ■: 2 to 1'L%
If it is less than 14%, the shape retention is poor and there is a risk of warping or waviness in the molded product.On the other hand, if it exceeds 20'Mg)%, the hardness becomes high, brittleness occurs, and strength decreases. Both are undesirable as there is a possibility that this may occur. And within these ranges, 4 to 1 for the solid content of calcium silicate.
It is particularly preferable to use Q l and r of 1% because the shape retention property can be maintained without substantially any inconvenience.

By performing dehydration pressing at a pressure of about 10 to 200 kg/cm2 during molding of the molded product, it has a high strength of -°44 weight of 0.2 to 1. It is possible to obtain a molded product of 0.0 g/cm', and when the pressure is less than 10 kg/cm" or when dehydration molding is performed without pressing, it has higher strength and bulk density of 0.06 than conventional calcium silicate insulation materials. ~0.13g/cm'
It is possible to obtain a molded article of about 100%. The high-density product of +iif M is useful, for example, as artificial wood, and the latter low-density product is useful as a heat-resistant heat insulating material. Also, the molding means I)11
In addition to the above, any material such as paper forming, extrusion molding, etc. may be selected depending on the shape, purpose, use, etc. of the final product.

It is appropriate to dry the molded body at a temperature of about 100 to 150°C. If the drying temperature is lower than 100°C, the adhesion between the emulsions 717.1 will be insufficient and it will take a long time to dry, while if it exceeds 150°C, the calcium silicate will thermally decompose and the crystal system will change. Both are unfavorable because they may cause a decrease in strength.

Furthermore, in the present invention, the molded article may be reinforced with a fiber reinforcing material such as 6r1 child fibers, and other additives may be used as appropriate as long as they do not impede the purpose of the present invention.

[Example] All parts and percentages used in the examples below are expressed as ξ by weight, and various physical properties were measured by the following methods.

Bulk density: Determined by drying the test specimen at 150° C. for 24 hours, and then measuring the weight and dimensions.

Bending strength, according to JIS A 1408. However, the dimensions of the test specimen were 60 x 200 mm and the thickness was 17 to 25 mm.

Specific strength: Calculated as bending strength/(bulk density)2.

Thermal conductivity: According to JIS A 1412 (flat plate comparison method). However, the test specimen dimensions were 200 x 200 mm and the thickness was 17 to 25 mm.

Water absorption rate: According to JIS^5418. However, the immersion time was 2 hours.

Nonflammability test: Conformed to JIS A 1321. however,
The dimensions of the test specimen in the surface test were 200 x ZOO mm and a thickness of 17 to 25 mm, or 200 x 220 mm and a thickness of 17 x 25 mm.

Linear shrinkage rate: According to JIS A 9510. 1000
Shrinkage percentage (%) after heating for 3 hours at °C.

Examples 1 to 6 A mixture consisting of 104 parts of silica sand, 100 parts of quicklime, and 4000 parts of water was charged into a stirring autoclave, and reacted with stirring at 210°C and 18 kg/am for 6 hours to produce calcium silicate mainly composed of xonotrite. A hydrate was obtained.

Obtained 5% hydrate slurry of calcium silicate 100
(solid content) of acrylic styrene emulsion (EX manufactured by Nippon Carbide Industries Co., Ltd.) in the amounts shown in the table.
,l,EX,2. EX, 3) (solid content equivalent), alkali-resistant glass fiber (13 mm long chopped strand, manufactured by Alka), wollastonite staple fiber (NYCO
After thorough stirring, etherified starch (Excell No. 3, manufactured by Hikaku Kagaku Co., Ltd.) was added, and stirring was continued. Next, Portland cement (white cement manufactured by Nippon Cement Co., Ltd.) and a water repellent (B Y +6 manufactured by Toray Silicone Co., Ltd.) were added and thoroughly stirred.

Next, the mixed slurry was poured into a mold of 400 x 450 mm, and pressure molded at a pressure of 40 to 60 kg/cm'' while vacuum dehydrating, and dried at 105°C for 6 hours to obtain a calcium silicate molded body. The various test results are shown in the table.

Examples 7-9 Calcium silicate hydrate slurry 100 used in Example 1
(solid content), add the additives used in Example 1 as shown in the table (no cement or water repellent added),
The obtained mixed slurry was vacuum dehydrated and molded in a 300 mmφ mold, and dried at 105° C. for 8 hours to obtain a calcium silicate molded body. The results of various tests on the molded product are as shown in the table.

Claims (3)

[Claims] (1) An aqueous slurry consisting of 100 parts by weight of calcium silicate hydrate, 5 to 30 parts by weight of acrylic styrene emulsion in terms of solid content, 0.5 to 15 parts by weight of starch, and water was formed and dried. A calcium silicate molded body characterized by: (2) Acrylic styrene emulsion is as follows (a) ~
A total of 100% by weight of monomers (c). (a) General formula H_2C=CR^1COOR^2 (however, R
^1 represents H or CH_2, R^2 represents C_1~
(representing a straight chain or branched alkyl group of C_2_0) acrylic acid or methacrylic acid ester monomer 30 to 94% by weight (b) Styrenic monomer 5 to 69% by weight (c) α of C_3 to C_5 , an aqueous emulsion comprising 1 to 30% by weight of a β-unsaturated monocarboxylic acid or dicarboxylic acid monomer. (3) The aqueous emulsion polymer emulsion according to item 2, wherein the styrenic monomer is styrene.