JPS63117980A - Ceramic composition - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to ceramic compositions.

[Prior Art] Conventionally, there is a ceramic composition consisting of ceramic, water and a hydrophilic urethane prepolymer (for example, JP-A-57-71851).

``Problems to be solved by the invention'' However, this product has problems such as short pot life and high viscosity.

[Means for Solving the Problems] The present inventors have intensively studied ceramic compositions with a long pot life and low viscosity, and as a result, have arrived at the present invention.

That is, the present invention provides ceramic powder (a), water (b), hydrophilic urethane prepolymer (c) and the general formula:
1 is H or an alkyl group having 1 to 8 carbon atoms, R2 is an alkyl group having 1 to 8 carbon atoms, or R1 and R2 are combined to form one ring in which the number of methylene groups is 2 to 11. You may do so. n is an integer from 2 to 6. The ring may in each case be substituted with a lower alkyl group. This is a ceramic composition for cast molding (hereinafter abbreviated as the composition of the present invention), which is characterized by comprising a cycloamidine represented by the following.

As the cycloamidines represented by the general formula (1), compounds described in JP-A-58-34878 can be used, and examples thereof include the following.

(1) Monocycloamidines: For example, 1-methylimidacillin, 1,2-dimethylimidacillin, 1-methyl-2-ethylimidacilline, 1-methyl-2-octylimidacillin; 1-methyl -1,4,5,6-titrahydropyrimidine, 1,2-dimethyl-1,4,5,6
-Titrahydropyrimidine, 1-methyl-2-ethyl-1,4,5,6-titrahydropyrimidine, 1-methyl-2-butyl-1,4,5,6-titrahydropyrimidine, 1-methyl-2 -octyl-1,4,5,6
-titrahydropyrimidine, 1,2.4-trimethyl-1°4.5.6-titrahydropyrimicin, etc.: and (2) general formula: [wherein m is 2 to 11. n is an integer from 2 to 6.

The ring may in each case be substituted with a lower alkyl group. ] Diaza-bicycloalkenes represented by, for example, 1,5-diaza-bicyclo(4,2,0)octene-5
゜1.4-diaza-bicyclo(3,3,0)octene-
4゜3-Methyl-1,4-diaza-bicyclo(3,3,
0) Octene-4゜1.5-diaza-bicyclo(4,3,0) Nonene-5゜1.8-diaza-bicyclo(7,3,0) dodecene-8
゜1.5-diaza-bicyclo(4,4,0)decene-5
゜1.8-diaza-bicyclo(7,4,0> tridecene-8゜1.8-diaza-bicyclo(5,3,0) decene-7゜1.8-diaza-bicyclo(5,4,0 ) undecene-7゜9-methyl-1,8-diaza-bicyclo(
5,4,0>undecene-7゜1.8-diaza-bicyclo(7,5,0)tetradecene-8゜1.10-diaza-bicyclo(7,4,0> tridecene-9゜1.14- Diaza-bicyclo(11,4
,0)hebutadecene-13゜Among these, preferred are diaza-bicycloalkenes represented by the general formula (1), particularly 1,8-diaza-bicyclo(5,4,0)undecene-7 [hereinafter referred to as DBU (Naori BU is a registered trademark of Sun-Apro ■)]
It is.

As salts of cycloamidines, Japanese Patent Publication No. 46-1018
Publication No. 8, Japanese Patent Publication No. 46-37503, Japanese Unexamined Patent Publication No. 1983
-117992 publication and JP-A-52-117993
For example, salts with phenols can be mentioned.

Examples of phenols include monovalent phenols such as phenol, cresols, xylenols, naphthols, trimethylphenols, tetramethylphenols, and pentamethylphenols.

Ethylphenols, n- and iso-propylphenols, n- and isobutylphenols.

Cyclohexylphenols, n- and in-amylphenols, iso-octylphenols.

Iso-nonylphenols, iso-dodecylphenols, di- and polysubstituted phenols (thymol, carvacrol, di-iso-alkylphenols, guaiacol, etc.); dihydric phenols such as catechols, resilcins, etc.: polyhydric phenols Examples include pyrogallol and phloroglucin.

Ceramic powders used as component (a) in the present invention generally can be turned into sintered bodies by heating to high temperatures, such as kaolin, clays, silica, alumina, feldspar, chinastone, mullite, and zircon.

Zirconia, titania, silicon carbide, cordierite.

There are magnesia, etc., and there are also mixtures of these various raw materials.

Water used as component (b) in the present invention includes soft water, hard water, ion exchange water, distilled water, and the like.

The hydrophilic urethane prepolymer used as component (c) in the present invention is, for example, poly(ethylene/propylene), which is a copolymer of ethylene oxide (hereinafter abbreviated as EO) and propylene oxide (hereinafter abbreviated as PO).
Water-soluble polyether polyols such as glycols, EO/PO coadducts of at least trivalent polyhydric alcohols (glycerin, trimethylolpropane, pentaerythritol, sorbitol, etc.) and excess per hydroxyl group of the polyether polyol [ For example, a reaction mixture obtained by reacting with a diisocyanate in an amount of more than 1 to 4 moles (more than 2 equivalents and up to 8 equivalents) can be mentioned.

The hydroxyl equivalent of the water-soluble polyether polyol is usually 500 or more, preferably 700 to 6,000.

Also, the EO content in water-soluble polymers is usually 35 to 95%.
, preferably 40 to 90%.

Examples of the diisocyanate include tolylene diisocyanate, xylylene diisocyanate, naphthylene diisocyanate, diphenylmethane diisocyanate, and biphenylene diisocyanate.

Examples include diphenyl ether diisocyanate, toridine diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and mixtures of two or more of these.

Alternatively, instead of the reaction mixture as described above, a urethane prepolymer containing substantially no free diisocyanate is synthesized by reacting in advance with the same number of moles of diisocyanate as the number of hydroxyl groups of the polyether polyol, A mixture to which free diisocyanate is subsequently added may also be used.

In addition, a polyether polyol and an insufficient amount of diisocyanate are reacted in advance to synthesize a hydrophilic urethane prepolymer with terminal hydroxyl groups, and then an excess amount of diisocyanate is reacted with this to synthesize a water-soluble terminal isocyanate group. A mixture of urethane prepolymer and free diisocyanate may also be used. Alternatively, the reaction mixtures may be prepared separately with different types of isocyanates and then mixed together later.

The NGO content of the hydrophilic urethane prepolymer (c) is usually 3-12%, preferably 4-10%.

When the NGO content is less than 3%, it is difficult to foam, the strength of the urethane foam is low, and it is difficult to take it out from the mold. 1
If it exceeds 2%, the reaction within the mold becomes intense and it becomes difficult to obtain a urethane foam with uniform cells.

The composition of the present invention may contain an organic solvent and a coloring agent, if necessary.
Stabilizers and the like may also be added.

In the composition of the present invention, the amount of the cycloamidine salt used as component (d) is usually 0.1 to 20% by weight, preferably 0.5% by weight, based on the hydrophilic urethane prepolymer as component (c). -15% by weight, more preferably 1-10% by weight. If component (c) is more than 20% by weight, strength development is slow and demolding cannot be performed in a short period of time. Moreover, if it is less than 0.1% by weight, the viscosity increases rapidly until hardening, making casting difficult.

The amount of water used in component (b) to be mixed to make a slurry of the ceramic powder in component (a) is as follows:
It is usually 20 to 70% by weight, preferably 30 to 60% by weight. If the amount of water is less than 20% by weight, the slurry viscosity will be high and workability will be poor; if it is more than 70% by weight, the dispersion stability of the slurry will be poor and the ceramic powder will tend to settle, and the Due to the increased moisture content, it takes a long time to dry the foam molded product, and the shrinkage increases.

The amount of hydrophilic urethane prepolymer used as component (c) is:
Usually 5 to 30% by weight based on the ceramic powder of component (a)
, preferably 10 to 20% by weight. (c) component is 5
If it is less than % by weight, the porosity will be low and the density will be high. On the other hand, if the amount exceeds 30% by weight, the porosity increases, shrinkage and deformation during drying increase, and the strength of the molded product after firing decreases.

The composition of the present invention typically includes ceramic powder (a) and water (b).
and (d) were added and mixed to make a slurry,
It is prepared by adding the hydrophilic urethane prepolymer (c) and stirring and mixing thoroughly. Usually, the viscosity of the ceramic composition slurry after 40 seconds of addition and mixing of the hydrophilic urethane prepolymer is 1.
00 to 8000 cps, pot life is 50 seconds to 5 minutes, curing time is 1 and a half minutes to 15 minutes, and demolding time is 3 minutes to 30 minutes. In the foamed ceramic casting method, this composition is injected into a mold and reacted and foamed within the mold to first create a urethane foam. The reaction within the mold is usually carried out at room temperature to 60°C. The urethane foam that was demolded after about 3 to 30 minutes was 50 to
The moisture in the urethane foam is removed by drying at 100°C for several hours. This is then heated in a high temperature furnace. This heating is performed for the purpose of burning off the polyurethane and sintering the ceramic powder, and the combustion is performed at a temperature of 400°C or less, and the sintering is performed at a temperature of 1100°C or more. After sintering, it is allowed to cool and then taken out from the heating furnace.

The foam molded product obtained in this way usually has a bulk specific gravity of 1.
．． 0-2.01 porosity 30-90%, water absorption rate 30-60
%, and the bending strength is 40 to 300 Kg/cm.

[Examples] The present invention will be further described below with reference to Examples, but the present invention is not limited thereto. Parts in Examples indicate parts by weight. In addition, in the examples, details of the hydrophilic urethane prepolymer used and methods for measuring slurry viscosity, pot life, curing time, and demolding time are as follows.

(Hydrophilic urethane prepolymer 1) EO, POO polymer using ethylene glycol as an initiator [average molecular weight 2900. EO content rate 8 children and NC
0=9%.

(Hydrophilic urethane prepolymer 2) EO, POO polymer using glycerin as an initiator [average molecular weight 4000, EO content 7% reacted with 328g isophorone diisocyanate to give NGO=7%.

(Slurry viscosity) Slurry viscosity (cps) after 40 seconds of addition and mixing of the hydrophilic urethane prepolymer.

(Pot life) (a) (b) other than hydrophilic urethane prepolymer (c)
Component (d) was mixed in advance to form a slurry, and the temperature was controlled at 20°C. Add component (c) of the same humidity to this,
After mixing and stirring for 20 seconds, the viscosity is measured using a B-type viscometer. (
c) The time required to reach 10,000 cps from the time of addition of the ingredients is defined as pot life.

(Curing time) Perform the same operation as the pot life measurement, and the viscosity is 100,000 cps.
The time required to reach this point is defined as the curing time.

(Demolding time) A ceramic composition obtained by adding and stirring the hydrophilic urethane prepolymer component (c) to a slurry mixture of components (a), (b), and (d) was placed in an iron mold (100X
100X10: The time required for the molded product to be removed from the mold after it has been cast (with a mold release agent applied to the inner surface) without leaving part of the mold attached to the mold or tearing.

Example 1. Comparative example 1 Partially synthesized mullite 100 water
50 Hydrophilic urethane prepolymer 110 Phenol salt of DBU 0.4 Synthetic mullite, water, and phenol salt of DBU were uniformly mixed to obtain a slurry ceramic.

Hydrophilic urethane prepolymer 1 was added to this and thoroughly stirred and mixed to obtain a composition of the present invention (Example 1).

Moreover, Comparative Example 1 was prepared by removing the phenol salt of DBU from the above composition.

A predetermined amount of these compositions was injected into an iron mold whose inner surface was previously coated with a wax-based mold release agent, and reacted and foamed at V temperature for 3 minutes. After removing the urethane foam from the mold, it was dried at 25°C for 24 hours, followed by 60'
It was dried at C for 48 hours. Next, the dry urethane foam was placed in a gas furnace, heated to 600°C over 8 hours, held for another 1 hour, then heated at a constant rate to 15QQ0C over 30 hours, and heated to 1500°C for 4 hours. The mixture was held for a period of time and then slowly cooled to obtain a fired ceramic product.

The performance and physical property values of the ceramic composition and fired product are as follows.

Example 1 Comparative Example 1 Ceramic composition slurry viscosity (cps) 6,000 13,
000 pot life (minutes, seconds) 1'
35" Cure time (min, seconds) 2'30"
1°08'' mold time (minutes, seconds) 5'3~5' Physical properties of fired product Bulk specific gravity 1.61 1.60 Porosity (%)
42 43 Water absorption rate (%) 40
43 Bending strength CK9/cti) 185
18216 Example 2, Comparative Example 2 Part Alumina
100 Water 30 Hydrophilic urethane prepolymer 15 Phenol salt of DBU 0.1 A composition of the present invention (Example 2) was obtained in the same manner as in Example 1.

Further, Comparative Example 2 was prepared by removing the DBU phenol salt from the above composition.

Ceramic fired products were obtained using these compositions in the same manner as in Example 1.

The performance and physical property values of the ceramic composition and fired product are as follows.

Example 2 Comparative Example 2 Ceramic composition slurry viscosity (cps) 6,500 65,
000 pot life (minutes, seconds) 1'
30″ Curing time (minutes, seconds) 2’05″ 47″ Mold time (minutes) 5’2 to 4’ Example 2 Comparative example 2 Physical properties of fired product Bulk specific gravity 1.80 1.82 Porosity (%)
56 54 Water absorption rate (%) 51
49 Bending strength (Kg/crtr) 26
8 272 Example 3, Comparative Example 3
Partially synthesized mullite 50 cordierite 50 water
40 Hydrophilic urethane prepolymer 25 Hydrophilic urethane prepolymer 15 Phenol salt of DBU 0.1 A composition of the present invention (Example 3) was obtained in the same manner as in Example 1.

Further, Comparative Example 3 was prepared by removing the phenol salt of DBU from the above composition.

Ceramic fired products were obtained using these compositions in the same manner as in Example 1.

The performance and physical property values of the ceramic composition and fired product are as follows.

Example 3 Comparative Example 3 Ceramic composition slurry viscosity (cps) 450 3,00
0 Pot life (minutes, seconds) 3'22"2'
05″Curing time (minutes, seconds) 5’30”
4'OO'' demolding time (min) 20'
15' fired product physical properties bulk specific gravity 1.50 1.55 porosity (%)
51 50 Water absorption rate (%) 40
42 Bending strength (Kfl/crtl) 179
175 [Effects of the Invention] The composition of the present invention has the effects that it has a long pot life and can be demolded in a short time, and that the slurry viscosity after addition of the hydrophilic urethane prepolymer is low and has excellent workability. .

Claims (1)

[Claims] 1. Ceramic powder (a), water (b), hydrophilic urethane prepolymer (c), and general formula: ▲There are numerical formulas, chemical formulas, tables, etc.▼ (1) [In the formula, R_1 is H or an alkyl group having 1 to 8 carbon atoms,
R_2 may be an alkyl group having 1 to 8 carbon atoms, or R_1 and R_2 may be combined to form one ring in which the number of methylene groups is 2 to 11. n is an integer from 2 to 6. The ring may in each case be substituted with a lower alkyl group. ] cycloamidine salt (d
) A ceramic composition for cast molding, characterized in that it consists of: 2, the amount of (d) is 0.1-20 based on the weight of (c)
% of the composition of claim 1. 3. The cycloamidines have the general formula: ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (2) (In the formula, m is an integer from 2 to 11 and n is an integer from 2 to 6. In either case, the ring is 4. The composition according to claim 1 or 2, which is a diaza-bicycloalkene represented by: -Diaza-
The composition according to claim 3, which is a salt of bicyclo(5,4,0)undecene-7. 5. The composition according to any one of claims 1 to 4, wherein the salt is a phenol salt.