JP2011240618A - Additive for ceramics extrusion molding and composition for ceramics extrusion molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an additive for extrusion molding in manufacturing a ceramics molded product by extrusion molding, and a composition for extrusion molding containing the additive for extrusion molding.SOLUTION: The additive [1] for ceramics extrusion molding contains a polyalkylene glycol fatty acid ester (a) represented by following formula (1) and a 12-22C straight chain unsaturated fatty acid (b), and a mass ratio (a):(b) between the components (a) and (b) is 96:4 to 99:1. In the formula X-O-(AO)n-COR (1): X is a hydrogen atom or COR; COR is a 12-22C straight chain unsaturated fatty acid acyl group; AO is one or more kinds of 2-3C oxyalkylene groups; and n is an average addition number of moles of the oxyalkylene groups and is 5-8. The composition [2] for ceramics extrusion molding contains: a ceramics raw material powder, a binder principally consisting of water-soluble cellulose derivative; water; and the additive for ceramics extrusion molding.

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.

Examples of the method for producing the ceramic molded body include extrusion molding, injection molding, pressure molding, and sheet molding. Extrusion molding is suitable as a molding method for products having a constant cross-sectional shape, and specific examples of the extrusion molding include DPF (Diesel Particulate Filter), honeycomb catalyst carrier and the like.
The DPF and the honeycomb catalyst carrier have a cell structure called a honeycomb structure. DPF is a filter that has the function of capturing particulates harmful to the human body contained in exhaust gas of diesel vehicles, etc., and the honeycomb catalyst carrier has the function of purifying harmful gas contained in exhaust gas into harmless gas. It is a catalyst support.
DPFs used in automobile exhaust filters are more harmful to the human body contained in exhaust gas due to the recent reduction of environmental impact and the tightening of exhaust regulations for diesel vehicles such as EuroVI, which will be enforced in Europe in 2012. It is required to capture fine particles, and the honeycomb catalyst carrier is required to have the ability to react the catalyst and harmful gas more efficiently in order to improve the purification performance to make harmful gas contained in exhaust gas harmless. It has been. Since the honeycomb catalyst carrier has a higher probability of the capture function / catalyst and the harmful gas reacting as the specific surface area of the contact surface with the exhaust gas increases, it is required to reduce the cell wall thickness of the honeycomb structure.
However, as the cell wall thickness becomes thinner, the shape of the die becomes more complicated, which causes a problem that the extrusion rate of the molding composition is lowered and the productivity is lowered. Therefore, an additive for extrusion molding that has an effect of improving the extrusion speed is indispensable at the time of extrusion molding in order to cope with the thinning of the cell wall thickness and improve the productivity.

A surfactant such as a fatty acid ester has been proposed as an additive having an effect of improving the extrusion speed (Patent Document 1). However, the effect of improving the extrusion speed is not sufficient only by adding a fatty acid ester. If a fatty acid ester with high hydrophilicity is used, the clay will adhere to the equipment used, and the work of removing the adhered clay will be required, resulting in workability. There has been a problem that it becomes a cause of contamination or foreign matter contamination at the time of material switching.
Further, fatty acid salts and the like have been proposed as additives having an effect of improving the extrusion speed (Patent Document 2). However, the effect of improving the extrusion speed is not sufficient only by adding a fatty acid salt or the like, and there is also a problem that a springback phenomenon occurs in which the extruded product discharged from the die swells due to the release pressure.
From these backgrounds, there is a demand for the development of an additive for extrusion molding that is excellent in workability at the time of kneading, excellent in moldability at the time of extrusion molding, and has a high effect of improving the extrusion speed at the time of extrusion molding.

JP 7-290430 A JP 2002-293645 A

The problem to be solved by the present invention is that a ceramic extrusion additive having good workability and formability and high extrusion speed improvement effect during ceramic extrusion molding, and ceramic extrusion containing the extrusion molding additive It is to provide a molding composition.

As a result of intensive investigations to solve the above problems, the present inventors surprisingly incorporated a specific amount of a linear unsaturated fatty acid into a polyalkylene glycol fatty acid ester, thereby surprisingly using this as an additive for extrusion molding. The workability and formability of the blended ceramic extrusion molding composition were improved, and the extrusion speed was greatly improved, and the present invention was completed.

That is, the present invention
[1] (a) a polyalkylene glycol fatty acid ester represented by the following formula (1) and (b) a linear unsaturated fatty acid having 12 to 22 carbon atoms, the ratio of which is (a) :( b ) = 96: 4 to 99: 1, additive for ceramic extrusion,
X-O- (AO) n-COR (1)
(In the formula, X represents a hydrogen atom or COR, COR represents a linear unsaturated fatty acid acyl group having 12 to 22 carbon atoms, and AO represents one or more oxyalkylene groups having 2 or 3 carbon atoms. (The average number of moles added of the oxyalkylene group is 5 to 8.)
[2] A composition for ceramic extrusion, comprising a ceramic raw material powder, a binder mainly composed of a water-soluble cellulose derivative, water, and the additive for ceramic extrusion described in [1] above.
[3] The ceramic extrusion molding composition according to [2], wherein the ceramic raw material powder is cordierite.

The extrusion molding composition obtained by mixing the extrusion molding additive of the present invention with the ceramic raw material powder is less likely to cause troubles such as adhering to the kneader during kneading and has good workability. In addition, the extrusion speed does not decrease during the molding of thin-film moldings, productivity can be improved, the springback phenomenon of the moldings is suppressed, and excellent moldability with little deformation is achieved. Can do.

The present invention is a ceramic extrusion additive containing (a) a polyalkylene glycol fatty acid ester represented by the following formula (1) and (b) a linear unsaturated fatty acid having 12 to 22 carbon atoms.
X-O- (AO) n-COR (1)
In the formula (1), X is a hydrogen atom or COR, and COR represents a linear unsaturated fatty acyl group having 12 to 22 carbon atoms. Carbon number of the linear unsaturated fatty acid is 12-22
, Preferably 14-20, more preferably 18. If the carbon number is less than 12, the effect of improving the extrusion speed is lowered, which is not preferable. On the other hand, when the number of carbon atoms is larger than 22, the hydrophobicity becomes strong and the solubility in water is lowered, which is not preferable. Although details are unknown, it is thought that by containing an unsaturated bond, it shows weak hydrophilicity while being a long-chain alkyl, and hydrophilicity that cannot be obtained simply by adding an oxyalkylene group to a saturated fatty acid is obtained. It is done.
Examples of the linear unsaturated fatty acid from which the linear unsaturated acyl group is derived include, for example, Linderic acid, Tuzic acid, Fizeteric acid, Myristoleic acid, Palmitoleic acid, Petroceric acid, Oleic acid, Elaidic acid, Asclepic acid, Baxen Acid, gadoleic acid, gondoic acid, cetoleic acid, erucic acid, brassic acid, linoleic acid, hiragoic acid, α-eleostearic acid, β-eleostearic acid, punicic acid, linolenic acid, moloctic acid, stearidonic acid, arachidone Examples include acids and fatty acids such as sardine acid, and one or more of these mixed fatty acids may be used. Preferred are palmitoleic acid, oleic acid, linoleic acid, and linolenic acid, and more preferred is oleic acid.

In the formula (1), AO is an oxyalkylene group having 2 or 3 carbon atoms, and examples thereof include an oxyethylene group and an oxypropylene group. When 80 mol% or more is an oxyethylene group, the resulting polyalkylene glycol fatty acid This is preferable because the solubility of the ester in water is improved. n is the average number of added moles of the oxyalkylene group, and is 5 to 8, preferably 6 to 7. If n exceeds 8, the effect of improving the extrusion rate of the polyalkylene glycol fatty acid ester decreases, which is not preferable. When n is smaller than 5, the hydrophobicity becomes strong and the solubility in water is not preferable.

The polyalkylene glycol fatty acid ester represented by the formula (1) can be produced by a method known per se. For example, a method of reacting a polyalkylene glycol and a fatty acid, a method of reacting a polyalkylene glycol and a fatty acid halide, a method of transesterifying a polyalkylene glycol and a fatty acid ester under an acid catalyst or an alkali catalyst, and adding an oxyalkylene to a fatty acid The method of esterifying a polyalkylene glycol and a fatty acid under an acid catalyst is preferable.
The type and amount of acid catalyst used when the esterification reaction of polyalkylene glycol and fatty acid in the presence of an acid catalyst is not particularly limited, but the acid catalyst is preferably methanesulfonic acid or toluenesulfonic acid, and the amount used is polyalkylene. 0.01-5 mass parts is preferable with respect to 100 mass parts of total amounts of glycol and fatty acid. Although reaction temperature is not specifically limited, 80-160 degreeC
Is more preferable, and it is 100-140 degreeC more preferably. Moreover, in order to improve a reaction rate, it is preferable to make it react in a pressure-reduced state, blowing in inert gas, such as nitrogen. The pressure is not particularly limited, but is preferably a reduced pressure of −0.088 MPaG or less (100 mmHg or less).
The amount of polyalkylene glycol and fatty acid charged and the reaction time can be appropriately set in consideration of the molecular weight of polyalkylene glycol, the type of fatty acid used, and the like.

The additive for ceramic extrusion molding of the present invention essentially comprises (b) a linear unsaturated fatty acid. Carbon number of the linear unsaturated fatty acid is 12-22
, Preferably 14-20, more preferably 18. If the carbon number is less than 12, the effect of improving the extrusion speed is lowered, which is not preferable. On the other hand, when the number of carbon atoms is larger than 22, the viscosity becomes high, which is not preferable because workability is lowered.
By containing an unsaturated bond, it is preferable because weak hydrophilicity can be obtained while being a long-chain alkyl. Examples of the linear unsaturated fatty acids include, for example, Linderic acid, Tzu acid, Fizeteric acid, Myristoleic acid, Palmitoleic acid, Petrothelic acid, Oleic acid, Elaidic acid, Asclepic acid, Vaxenoic acid, Gadelic acid, Gondoic acid, Cetoleic acid , Erucic acid, brassic acid, linoleic acid, hiragoic acid, α-eleostearic acid, β-eleostearic acid, punicic acid, linolenic acid, moloctic acid, stearidonic acid, arachidonic acid, succinic acid, etc. These 1 type or 2 types or more may be used. Preferred are palmitoleic acid, oleic acid, linoleic acid, and linolenic acid, and more preferred is oleic acid.

The ratio of (a) and (b) is (a) :( b) = 96: 4 to 99: 1 in mass ratio, more preferably (a) :( b) = 96: 4 to 98: 2. It is. The ratio of (a) and (b) can be prepared by adding (b) a linear unsaturated fatty acid having 12 to 22 carbon atoms to (a) polyalkylene glycol fatty acid ester.
Fatty acid and polyalkylene glycol fatty acid ester are considered to have different mechanisms of action on ceramic raw material powder, while fatty acid is adsorbed on ceramic raw material powder, whereas polyalkylene glycol fatty acid ester is coordinated on ceramic raw material powder. I think that. It is considered that a synergistic effect can be obtained by simultaneously operating these two action mechanisms, and the extrusion speed can be increased. If the ratio of (b) in the additive for ceramic extrusion molding of the present invention is less than 1 in terms of mass ratio, the synergistic effect is small and the extrusion speed cannot be sufficiently improved, which is not preferable. On the other hand, if the ratio of (b) exceeds 4 in mass ratio, no extrudable clay can be obtained even if kneading is continued, and an extruded product cannot be obtained.

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 ceramic raw material powder, may be added during kneading, or may be added after preparing the clay. The usage form may be used as it is, or may be diluted or emulsified with water as necessary, and may be used in combination with a wetting agent, other surfactants, and the like. As the wetting agent, for example, ethylene glycol, dipropylene glycol, glycerin and the like, and as other surfactants, oxyalkylene derivatives such as polyethylene glycol and polypropylene glycol, higher alcohol ethylene oxide adduct, higher alkylamine ethylene oxide adduct, Nonionic surfactants such as polyoxyethylene polyoxypropylene glycol, anionic surfactants such as carboxylates, sulfonates, sulfates and phosphates derived from higher alcohols, cationic surfactants, amphoteric Surfactant can be used and these 1 type (s) or 2 or more types 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 per 100 parts by mass of the ceramic raw material powder. Part by mass, more preferably 1 to 4 parts by mass.
Examples of the ceramic raw material powder used in the ceramic extrusion molding composition according to the present invention include silicon, titanium, zirconium, silicon carbide, boron carbide, titanium carbide, zirconium carbide, tungsten carbide, silicon nitride, boron nitride, Examples include aluminum nitride, aluminum oxide, zirconium oxide, mullite, cordierite, aluminum titanate, sialon, kaolin, talc, zeolite, aluminum hydroxide, fused silica, or quartz, and one or more of these are used. be able to. There is no restriction | limiting in particular about the combination in the case of using 2 or more types. Preferred are aluminum oxide, zirconium oxide, mullite, cordierite and zeolite, and more preferred is cordierite.

The composition for ceramic extrusion according to the present invention contains, in addition to the ceramic raw material powder and the additive for ceramic extrusion, a binder mainly composed of a water-soluble cellulose derivative and water.
Examples of the binder mainly composed of a water-soluble cellulose derivative include hydroxypropylmethylcellulose, hydroxypropylethylcellulose, hydroxyethylmethylcellulose, methylcellulose, hydroxyethylcellulose, and carboxymethylcellulose. Moreover, polyvinyl alcohol, polyacrylic acid, polyethylene oxide, an ethylene vinyl acetate copolymer, etc. are mentioned as another binder, These can use 1 type (s) or 2 or more types. There is no restriction | limiting in particular about the combination in the case of using 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 ceramic raw material powder. It is 15-85 mass parts with respect to 100 mass parts, Preferably it is 20-50 mass parts.

The extrusion molding composition of the present invention is obtained, for example, by uniformly mixing a predetermined amount of ceramic raw material powder and a binder, then adding water and a ceramic extrusion additive, and then kneading. By conveying to an extruder provided with a die having a structure such as a honeycomb 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.

[Method for preparing clay (composition for extrusion molding)]
Cordierite (P) (SS-600, manufactured by Marusu Yakugyo Co., Ltd.), hydroxypropyl methylcellulose (MC) (Metroze 65SH-4000, Kneader N-5 type, manufactured by Ishikawa Tokiko Co., Ltd.) (Made by Shin-Etsu Chemical Co., Ltd.), knead until uniform, then add water (W) (tap water) and extrusion additive (Ad), and further knead to prepare the clay did. Table 1 shows the use ratio and the blending mass. At this time, the hardness of the earthen earth is measured by using a hardness meter (CLA HARDNESS TESTER, manufactured by NGK Co., Ltd.), and the earthenness hardness is within a certain range (11.5 ± 0.5). It was confirmed.

[Extrusion test method]
The prepared dough is put into an extruder (small clay kneader SY-05S type, manufactured by Ishikawa Tokiko Co., Ltd.), subjected to an extrusion test, and the extrusion pressure, the extrusion speed, and when transferring the dough. Workability was evaluated (◯: no earthen soil adheres to the kneader, Δ: earthen earth adheres to the kneader but easily peels, x: earthen earth adheres to the kneader and is difficult to remove). Further, the base was a sheet (5 mm × 45 mm), and the lateral width of the extruded product was measured as an evaluation of the spring back. The extrusion test was performed by setting the inverter control of the extruder to a frequency of 30 Hz in order to make the screw rotation speed of the extrusion test machine constant.
In extrusion molding, it is required that extrusion pressure is low, extrusion speed is high, and width expansion is small, but not only these measured values are evaluated individually, but also comprehensive evaluation of formability based on these measured values. Was performed according to the following equation:
If the clay contains the same ceramic raw material powder, the smaller the numerical value of the formability, the better the formability.
[Formability] = [Extrusion pressure (MPa)] / [Extrusion speed (cm / s)] × [Horizontal width (mm)]

[Example 1]
As a ceramic extrusion additive (Ad), a blend of polyoxyethylene (n = 7) monooleate: oleic acid = 96.5: 3.5 in mass ratio was used. Table 2 shows the results of the soil hardness, workability, extrusion pressure, extrusion speed, width, and formability.
[Example 2 and Comparative Examples 1-5]
The extrusion test was carried out by changing the additive for ceramic extrusion of Example 1 to (a) polyalkylene glycol fatty acid ester and (b) fatty acid shown in Table 2. In combination with the results of Example 1, Table 2 shows the mass ratio of (a) polyalkylene glycol fatty acid ester and (b) fatty acid used, and the hardness of the clay, workability, extrusion pressure, extrusion speed, width, and formability. The results are shown.

By comparison between Example 1 and Comparative Example 1 in Table 2 and Example 2 and Comparative Example 2, the ceramic extrusion additive of the present invention was obtained because it contains the fatty acid (b). It can be seen that even if the hardness of the clay is the same, the effect of improving the extrusion speed is high and the moldability is excellent.
Moreover, since the additive for ceramic extrusion molding of this invention contains the polyalkylene glycol fatty acid ester of (a) by comparison with Example 1 and 2 and the comparative example 3, the improvement effect of extrusion rate becomes high. It can be seen that the moldability is also excellent.
Furthermore, by comparison between Examples 1 and 2 and Comparative Example 4, the additive for extrusion extrusion of ceramics of the present invention uses a fatty acid ester containing an unsaturated bond, so that the effect of improving the extrusion rate is high, It can be seen that both formability and workability are excellent.
Further, as in Comparative Example 5, when the mass ratio of the fatty acid (b) exceeded 4, even when kneaded, no change in appearance was observed, and an extrudable clay was not obtained.

Claims (3)

(A) a polyalkylene glycol fatty acid ester represented by the following formula (1) and (b) a linear unsaturated fatty acid having 12 to 22 carbon atoms, the ratio of which is (a) :( b) = 96 : 4 to 99: 1 additive for ceramic extrusion.
X-O- (AO) n-COR (1)
(In the formula, X represents a hydrogen atom or COR, COR represents a linear unsaturated fatty acid acyl group having 12 to 22 carbon atoms, and AO represents one or more oxyalkylene groups having 2 or 3 carbon atoms. (The average number of moles added of the oxyalkylene group is 5 to 8.) The composition for ceramic extrusion molding containing ceramic raw material powder, the binder which has a water-soluble cellulose derivative as a main component, water, and the additive for ceramic extrusion molding of Claim 1. The composition for ceramic extrusion molding according to claim 2, wherein the ceramic raw material powder is cordierite.