JP5618212B2 - Ceramic extrusion additive and ceramic extrusion composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to an additive for extrusion when a ceramic molded body is produced by extrusion and an extrusion composition containing the additive for extrusion.

In ceramic extrusion molding, various raw materials (ceramic powder, binder, water, additives, etc.) are kneaded with a kneader to prepare a clay-like substance called a clay, and the shape required by extruding the clay with an extruder. It is a method of processing into objects. The obtained extrudate is cut into a required length, dried, and finally sintered to obtain various products.
Specific examples of the extruded product include sheet products used for multilayer power distribution boards, DPF (Diesel), and the like.
Examples thereof include cellular products called honeycomb structures such as Particulate Filters) and honeycomb catalyst carriers.
In recent years, in order to improve the functionality of ceramic products, both sheet-like products and cellular products have been reduced in size and thickness. As the film thickness is reduced, the shape of the die of the extrusion molding machine becomes more complicated, which causes a problem that the extrusion speed is lowered and the production capacity per unit time is lowered.
In addition, since the shape retention force of the green body partition decreases as the film becomes thinner, this is not a big problem for sheet products that have a flat structure and little influence of the shape retention force, but the structure is three-dimensional and the shape retention force of the partition wall. In the cellular product having a large influence, there are problems that the green body immediately after extrusion molding cannot retain the cell shape, and that the cell shape cannot be retained during cutting and drying.
As a method for improving the shape retention of a green body, a method for increasing the amount of a water-soluble cellulose derivative such as methyl cellulose as a binder and a method for reducing the amount of water used during kneading are known. However, just increasing the amount of the water-soluble cellulose derivative or reducing the amount of water has a problem that the clay becomes hard and a clay-like clay that can be extruded cannot be obtained.

As a method for producing a cellular product, use of a nonionic surfactant such as a fatty acid ester has been proposed as a molding aid for improving mass productivity (Patent Document 1). However, with this method, an effect of improving the extrusion speed can be obtained, but the shape retention of the green body after the extrusion molding is not sufficient.
As a method for producing a ceramic molded body, use of a polycarboxylic acid-based dispersant (polyoxyalkylene monoalkyl monoallyl ether / maleic acid copolymer) has been proposed (Patent Document 2). In this document, a polyoxyalkylene monoalkyl monoallyl ether having a relatively low molecular weight (up to an average addition mole number of about 110) is used, and a ceramic sheet using polyvinyl alcohol as a binder. It has been shown that the performance (glossiness, flexibility) of the sheet product has been improved.
However, in the extrusion molding of cellular products, even if the polycarboxylic acid-based dispersant is used, it has not been possible to obtain a sufficient shape retention for the green body after molding.
In view of these backgrounds, there has been a demand for the development of an additive for ceramic extrusion, which is excellent in moldability and has a high effect of improving the extrusion speed and the effect of improving the shape retention force at the time of extrusion molding of the cellular product.

JP 7-290430 A Japanese Patent Laid-Open No. 7-25665

The problem to be solved by the present invention is an additive for ceramic extrusion, which is excellent in moldability and has a high effect of improving extrusion speed and shape retention, and a ceramic containing the additive for extrusion molding. It is to provide an extrusion composition.

As a result of diligent investigations to solve the above problems, the present inventors have formulated a polycarboxylic acid copolymer having a large number of polyoxyalkylene addition moles, thereby forming moldability and extrusion of a composition for ceramic extrusion molding. The inventors have found that the speed and shape retention can be improved, and have completed the present invention.

That is, the present invention
[1] Structural unit (a) 50 based on a polyoxyalkylene derivative represented by the following formula (1)
To 99% by mass, 1 to 50% by mass of the structural unit based on the dicarboxylic acid or maleic anhydride represented by the following formula (2) and 1% to 50% by weight of the structural unit (U) 0 ~ 30% by mass
A ceramic extrusion additive characterized by being a copolymer having a composition of:

(R ¹ , R ² , and R ³ are each independently a hydrogen atom or a methyl group, AO is one or more oxyalkylene groups having 2 to 4 carbon atoms, and in the case of two or more types, block addition is also possible. R ⁴ may be a random addition, and R ⁴ represents a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, q = 1 or 2, p = 151 to 300, and r = 0 or 1.

(V is -OM ² or W- (AO) _s R ⁵ , W is an ether group or imino group, AO is one or more of oxyalkylene groups having 2 to 4 carbon atoms, and in the case of two or more R ⁵ is a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, M ¹ and M ² are each independently a hydrogen atom, an alkali metal, an alkaline earth metal, ammonium, or organic Represents ammonium, s = 1 to 300.)
[2] It relates to a ceramic extrusion molding composition containing raw material powder, a water-soluble cellulose derivative, water, and the additive for ceramic extrusion molding according to [1].

By using the additive for extrusion molding of the present invention, it is possible to reduce the amount of water in the composition for ceramic extrusion molding, or the binder, and the composition for ceramic extrusion molding has workability such as extrusion speed. Excellent. Further, the shape retention force immediately after molding is improved, and the temporal stability is significantly improved.
Therefore, it is useful for forming a honeycomb structure corresponding to a small size and a thin film, which has been a problem in the past, and has a remarkable effect in that a formed body with less deformation and deformation can be provided.

The additive for extrusion molding of ceramics of the present invention comprises 50 to 99% by mass of a structural unit (a) based on a polyoxyalkylene derivative represented by the general formula (1), a dicarboxylic acid represented by the general formula (2), or anhydrous A copolymer having a composition of 1 to 50% by mass of the structural unit (I) based on maleic acid and 0 to 30% by mass of the structural unit (U) based on another copolymerizable monomer is an essential component.

In the formula (1), R ¹ , R ² and R ³ are each independently a hydrogen atom or a methyl group, preferably a hydrogen atom. In the formula (1), AO is an oxyalkylene group having 2 to 4 carbon atoms, and examples thereof include an oxyethylene group, an oxypropylene group, and an oxybutylene group, and these may be used alone or in combination of two or more. In the case of two or more types, block addition or random addition may be used. Preferably it is an oxyethylene group or an oxypropylene group, more preferably an oxyethylene group and an oxypropylene group are added in a mass ratio of 40 to 99: 1 to 60, more preferably 90 to 99: 1 to 10 It is a thing.
In Formula (1), p is the average addition mole number of a C2-C4 oxyalkylene group, and is 151-300, Preferably it is 151-250. If the value of p exceeds 300, the resulting compound has a high viscosity, which makes it difficult to produce. On the other hand, if the value of p is smaller than 151, the temporal stability of the shape retention force is lowered, which is not preferable.
q is the number of repeating methylene groups and is 1 or 2, preferably 1.
r is the number of carbonyl groups and is 0 or 1.

Examples of the hydrocarbon group having 1 to 4 carbon atoms represented by R ⁴ in the formula (1) include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secondary butyl group, and a tertiary butyl group. Yes, these may be used alone or in combination of two or more. Preferably, it is a hydrogen atom or a methyl group. In particular, when r = 0, the introduction of a hydrocarbon group as R ⁴ by an etherification reaction increases the viscosity of the polyoxyalkylene derivative and makes it difficult to produce. Therefore, a hydrogen atom is more preferable. . In addition, when r = 1, R ⁴ is more preferably a methyl group. When the number of carbon atoms of the hydrocarbon group represented by R ⁴ exceeds 4, it is not preferable because the foaming property becomes high.

Examples of the structural unit (i) based on dicarboxylic acid or maleic anhydride include maleic anhydride, maleic acid, and fumaric acid. In the formula (2), M ¹ and M ² are a hydrogen atom, an alkali metal, an alkali Earth metal, ammonium or organic ammonium. Examples of the alkali metal include lithium, sodium, and potassium. Examples of the alkaline earth metal include magnesium and calcium. Organic ammonium is an ammonium derived from organic amines, and examples of organic amines include alkanolamines such as monoethanolamine, diethanolamine, and triethanolamine, and alkylamines such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, and triethylamine. Preferred are monoethanolamine, diethanolamine, methylamine, ethylamine, and diethylamine.
V in the formula (2) represents —OM ² or —W— (AO) sR ⁵ . W is an ether group or an imino group, the ether group is represented by —O—, and the imino group is represented by —NH—. AO represents 1 type (s) or 2 or more types of a C2-C4 oxyalkylene group. s is an average addition mole number of a C2-C4 oxyalkylene group, and is 1-300, Preferably it is 10-150, More preferably, it is 20-70. If the value of s exceeds 300, the resulting compound tends to increase in viscosity, which makes production difficult. R ⁵ is a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, and examples of the hydrocarbon group include methyl, ethyl, propyl, isopropyl, allyl, butyl, isobutyl, sec-butyl, A tributyl group is mentioned, and these may be used alone or in combination of two or more. Preferably, they are a hydrogen atom and a methyl group. When the number of carbon atoms of the hydrocarbon group represented by R ⁵ exceeds 4, foaming properties are increased, which is not preferable.

The copolymer having a polyoxyalkylene derivative used for the additive for ceramic extrusion molding of the present invention is composed of 50 to 99% by mass of the structural unit (a) based on the polyoxyalkylene derivative represented by the general formula (1). The structural unit based on the dicarboxylic acid or maleic anhydride represented by (2) (A) 1 to 50% by mass and the structural unit based on another copolymerizable monomer (U) 0 to 30% by mass
However, (a) 80-99 mass%, (b) 1-20 mass%, (u) 0-20 mass% are preferable. As the structural unit (c) based on other monomer capable of copolymerization, it can be added within a range not deteriorating the effect of the present invention, and vinyl acetate, sodium allyl sulfonate, sodium methacryl sulfonate, methacrylic acid, acrylic An acid etc. are mentioned.
The weight average molecular weight of the copolymer used for the additive for ceramic extrusion molding of the present invention is 10,000 to 100,000, preferably 15,000 to 50,000. A compound having a mass average molecular weight exceeding 100,000 is not preferable because it is difficult to produce due to high viscosity.

The copolymer used for the additive for ceramic extrusion molding of the present invention can be obtained by polymerization using a polymerization initiator by a known method. The polymerization method may be bulk polymerization or solution polymerization.
When water is used as a solvent in solution polymerization, persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate, hydrogen peroxide, and a water-soluble azo initiator can be used. Also, in solution polymerization, lower alcohols such as methanol, ethanol and isopropanol, aliphatic hydrocarbons such as n-hexane, 2-ethylhexane and cyclohexane, aromatic hydrocarbons such as toluene and xylene, acetone, methyl ethyl ketone, ethyl acetate, etc. In the case of polymerization using an organic solvent or bulk polymerization, organic peroxides such as benzoyl peroxide, di-t-butyl peroxide and t-butylperoxyisobutyrate, and azo series such as azobisisobutyronitrile Compounds can be used. In this case, a chain transfer agent such as thioglycolic acid or mercaptoethanol can also be used.
Particularly preferably, water is used in solution polymerization, and after manufacturing the polyoxyalkylene derivative, a maleic acid compound, an initiator, and water are collectively charged into a reaction vessel containing the polyoxyalkylene derivative, and an inert gas atmosphere. The polymerization is carried out at a polymerization temperature of 45 to 100 ° C. with stirring and under stirring.

The additive for ceramic extrusion molding of the present invention can be used as it is, but can be diluted with water, emulsified, or used in combination with other additives as necessary. For example, wetting agents such as ethylene glycol, dipropylene glycol and glycerin, oxyalkylene derivatives such as polyethylene glycol and polypropylene glycol, higher alcohol ethylene oxide adducts, higher alkylamine ethylene oxide adducts, nonionics such as polyoxyethylene polyoxypropylene glycol Anionic surfactants such as carboxylic surfactants, carboxylic acid salts derived from higher alcohols, sulfonates, sulfate ester salts, phosphate ester salts, cationic surfactants, and amphoteric surfactants can be used. Species or two or more can be used. There is no restriction | limiting in particular about the combination in the case of 2 or more types.
The addition amount of the additive for ceramic extrusion molding of the present invention is 0.1 to 15 parts by mass, preferably 1 to 10 parts by mass, more preferably 1 to 5 parts by mass with respect to 100 parts by mass of the ceramic powder. Part.
There is no restriction | limiting in particular about the addition method and usage form of the additive for ceramic extrusion molding of this invention. As an addition method, it may be added to the raw material powder, may be added during kneading, or may be added after preparing the clay.

The ceramic raw material powder used in the ceramic extrusion molding composition according to the present invention includes a ceramic powder obtained by firing, a ceramic raw material before firing, and a blend of ceramic raw materials, such as silicon and titanium. , Zirconium, silicon carbide, boron carbide, titanium carbide, zirconium carbide, tungsten carbide, silicon nitride, boron nitride, aluminum nitride, aluminum oxide, zirconium oxide, mullite, cordierite, aluminum titanate, sialon, kaolin, talc, zeolite, Aluminum hydroxide, fused silica, quartz, or the like can be used, and one or more can be used. There is no restriction | limiting in particular about the combination in the case of 2 or more types. Talc, kaolin, aluminum oxide, zirconium oxide, mullite, cordierite and zeolite are preferred, and talc, kaolin, aluminum oxide and cordierite are more preferred.

The composition for extrusion molding of ceramics according to the present invention can further contain a water-soluble binder and water, and the water-soluble binder is preferably a water-soluble cellulose derivative, such as hydroxypropylmethylcellulose, hydroxypropylethylcellulose, Hydroxyethyl methylcellulose, methylcellulose, hydroxyethylcellulose, or carboxymethylcellulose can be used. These binders can be used by 1 type (s) or 2 or more types, There is no restriction | limiting in particular about the combination in the case of 2 or more types.
The addition amount of the binder mainly composed of a water-soluble cellulose derivative is 1 to 20 parts by mass, preferably 3 to 15 parts by mass with respect to 100 parts by mass of the raw material powder, and the water content is 100 parts by mass of the raw material powder. It is 15-85 mass parts with respect to a part, Preferably it is 20-50 mass parts.

The extrusion molding composition of the present invention can be obtained, for example, by uniformly mixing a predetermined amount of raw material powder and a binder, and then adding water and a ceramic extrusion molding additive and kneading them. By conveying to an extruder provided with a die having a structure such as a body, a molded body having an intended structure can be obtained.
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to this.

The present invention will be further described below with reference to examples. Table 1 shows the molecular formula of the compound represented by the formula (1), the molecular formula of the compound represented by the formula (2), and the mass average molecular weight.

[Production Example 1]
Into a 3 liter flask equipped with a stirrer, thermometer, nitrogen gas inlet tube, reflux condenser, polyoxyethylene (average added mole number of ethylene oxide 210) oxypropylene (average added mole number 11 of propylene oxide) monoallyl ether 994 g (0.1 mol), 707 g of water, 58.8 g (0.6 mol) of maleic anhydride, and 24.2 g (0.1 mol) of sodium persulfate as a polymerization initiator at 35 ° C. Was replaced with nitrogen gas and reacted at 60 ± 2 ° C. for 10 hours. After completion of the polymerization reaction, neutralization was performed by adding 68 g of 28% aqueous ammonia (1.2 mol as ammonia), and 888 g of water was further added to obtain a 40% aqueous solution of the copolymer.

[Production Example 2]
In a 3 liter flask equipped with a stirrer, thermometer, nitrogen gas inlet tube and reflux condenser, polyoxyethylene (average added mole number of ethylene oxide 157) monoallyl ether 700 g (0.1 mol), water 510 g, anhydrous male 49.0 g (0.5 mol) of acid was added, 16.7 g (0.1 mol) of sodium persulfate was added as a polymerization initiator at 35 ° C., and the air in the system was replaced with nitrogen gas, and then 60 ± 2 ° C. For 10 hours. After completion of the polymerization reaction, 186 g of a 30% aqueous potassium hydroxide solution (1.0 mol as potassium hydroxide) was added for neutralization, and 592 g of water was further added to obtain a 40% aqueous solution of the copolymer.

[Production Example 3]
Polyoxyethylene (average number of moles of added ethylene oxide 210) oxypropylene (average number of moles of added propylene oxide 11) monoallyl ether mono was added to a 3 liter flask equipped with a stirrer, thermometer, nitrogen gas inlet tube and reflux condenser. 1005 g (0.1 mol) of acetate, 707 g of water and 58.8 g (0.6 mol) of maleic anhydride were added, and 24.2 g (0.1 mol) of sodium persulfate was added as a polymerization initiator at 35 ° C. The air was replaced with nitrogen gas and reacted at 60 ± 2 ° C. for 10 hours. After completion of the polymerization reaction, 160 g of a 30% aqueous sodium hydroxide solution (1.2 mol as sodium hydroxide) was added for neutralization, and 885 g of water was further added to obtain a 40% aqueous solution of the copolymer.

[Production Example 4]
In a four-necked flask equipped with a reflux condenser, a thermometer, a nitrogen gas inlet tube and a stirrer, 550 g of polyoxyethylene monoallyl monomethyl ether (average added mole number of ethylene oxide 110), 9.8 g of maleic anhydride and 300 ml of toluene were added. The temperature was raised to 50 ° C., 2.0 g of t-butylperoxy-2-ethylhexanoate was added, the temperature was raised to 70 ° C., and the copolymerization reaction was carried out at the same temperature for 10 hours while continuously passing nitrogen gas. . After the reaction, toluene was distilled off at 110 ° C. under reduced pressure to obtain a reddish brown solid.

[Production Example 5]
Into a four-necked flask equipped with a reflux condenser, a thermometer, a nitrogen gas inlet tube and a stirrer, 550 g of polyoxyethylene monoallyl monomethyl ether (average added mole number of ethylene oxide 11), 98 g of maleic anhydride and 300 ml of toluene were added. The temperature was raised to 50 ° C., 2.0 g of t-butylperoxy-2-ethylhexanoate was added, the temperature was raised to 70 ° C., and a copolymerization reaction was carried out at the same temperature for 10 hours while continuously supplying nitrogen gas. After the reaction, toluene was distilled off at 50 ° C. under reduced pressure to obtain a reddish brown transparent viscous liquid. 160 g of 30% aqueous sodium hydroxide solution (1.2 mol as sodium hydroxide) was added for neutralization, and 935 g of water was further added to obtain a 40% aqueous solution of the copolymer.

[Examples 1-3, Comparative Examples 1-3]
<Preparation and evaluation method of clay>
Cordierite (P) (SS-600, manufactured by Marusu Yakugyo GK Co., Ltd.), hydroxypropyl methylcellulose ((MC) (Metroze 65SH-4000), kneading machine (kneader N-5 type, manufactured by Ishikawa Tokiko Co., Ltd.) , Manufactured by Shin-Etsu Chemical Co., Ltd.), knead until uniform, then add water (W) (tap water) and additive for extrusion molding (Ad), further knead, At this time, the hardness of the earthen earth was measured using a hardness meter (CLA HARDNESS TESTER, manufactured by NGK Co., Ltd.).
<Extrusion test and evaluation method>
Extruder (small size) of the prepared dough using a die having a simple honeycomb shape (a shape in which four squares of length 12 mm × width 12 mm × wall thickness 1 mm are contained in a square of length 30 mm × width 30 mm × wall thickness 1 mm) Was put into a clay kneader SY-05S type (manufactured by Ishikawa Tokiko Co., Ltd.), an extrusion test was conducted, and an extrusion pressure and an extrusion speed were evaluated.
<Method for evaluating shape retention ability>
The shape retention strength was evaluated using the obtained extruded product. The shape-retaining force was evaluated from two viewpoints: immediately after extrusion molding and stability over time (temperature 25 ° C., humidity 50%, left standing for 1 day).
The shape retention strength evaluation immediately after extrusion molding was performed by visually observing the shape of the extruded product (○: retaining the cell shape, Δ: somewhat out of shape, ×: not retaining the cell shape, causing loss of shape. ).
With respect to those that were ○ and Δ in the visual evaluation, the elastic modulus (mN / mm 2) was calculated by the following method, and the value was used as the evaluation value. Put the extruded product (prepared to a 30 mm x 30 mm x 120 mm rectangular parallelepiped size) on a compression test board (φ100 mm) set on an autograph (AGS-J, 1 kN, Shimadzu Corporation), and speed of 5 mm / min. Then, a compression test of 5 mm was performed, and the elastic modulus was calculated. The larger the value of this elastic modulus, the better the shape retention force.
The stability over time was evaluated using a molded product having a visual evaluation of ◯ and Δ immediately after extrusion molding. The stability over time was evaluated from the two viewpoints of the degree of shape loss of the molded body and the surface state of the molded body.
The degree of shape loss of the molded body is determined by measuring the vertical width and the horizontal width of the molded body with calipers. The ratio of the vertical width to the horizontal width is 0.99 to 1.01, and the one out of this range is ×. did.
With respect to the surface state of the molded body, the one with a clean flat state was marked with ◯, and the one with cracks and wrinkles was marked with x.
Table 2 shows the amount of water at the time of preparing the clay, MC, hardness at the time of kneading, and Table 3 shows the results of the extrusion test and shape retention evaluation.

According to Table 3, the molded products of Examples 1 to 3 using the ceramic extrusion additive of the present invention having a large average addition mole number of the polyoxyalkylene derivative have a small average addition mole number of the polyoxyalkylene derivative. It can be seen that the stability over time of the shape retention force is superior to that of Comparative Example 1.
The comparative example 2 using an additive in which the average number of added moles of the polyoxyalkylene derivative was smaller than that of the comparative example 1 could not maintain the shape retention force immediately after molding.
The extrusion molding compositions of Examples 1-3 were compared to the composition of Comparative Example 3 using a nonionic surfactant of a type different from the ceramic extrusion additive of the present invention. The amount of water can be reduced (Table 2), and is far superior in terms of formability and shape retention.

Claims (2)

Structural unit (a) 50 based on a polyoxyalkylene derivative represented by the following formula (1)
To 99% by mass, 1 to 50% by mass of the structural unit based on the dicarboxylic acid or maleic anhydride represented by the following formula (2) and 1% to 50% by weight of the structural unit (U) 0 ~ 30% by mass
An additive for ceramic extrusion, which is a copolymer having the following composition:

(R ¹ , R ² , and R ³ are each independently a hydrogen atom or a methyl group, AO is one or more oxyalkylene groups having 2 to 4 carbon atoms, and in the case of two or more types, block addition is also possible. R ⁴ may be a random addition, and R ⁴ represents a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, q = 1 or 2, p = 151 to 300, and r = 0 or 1.

(V is -OM ² or W- (AO) _s R ⁵ , W is an ether group or imino group, AO is one or more of oxyalkylene groups having 2 to 4 carbon atoms, and in the case of two or more R ⁵ is a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, M ¹ and M ² are each independently a hydrogen atom, an alkali metal, an alkaline earth metal, ammonium, or organic Represents ammonium, s = 1 to 300.) A ceramic extrusion composition containing raw material powder, a water-soluble cellulose derivative, water, and the additive for ceramic extrusion molding according to claim 1.