JPH0618627B2 - Dispersant for molding in the production of sintered bodies - Google Patents

Description

TECHNICAL FIELD The present invention relates to a molding dispersant to be added to an inorganic powder together with a binder when producing a ceramic product or other sintered body.

2. Description of the Related Art In producing a sintered body from an inorganic powder such as a metal oxide or a metal complex oxide by an injection molding method, an extrusion molding method or the like, it is necessary to use a binder. Conventionally, it has been proposed to use a water-soluble polymer, a thermoplastic resin, a thermosetting resin, a wax, etc. as a binder for this purpose, but from the viewpoint of releasing property and degreasing property, recently, paraffin wax and microcrystalline wax have been proposed. There is a tendency to use non-polar substances such as waxes and low molecular weight polyolefins.

Problems to be Solved by the Invention However, although good results can be expected in terms of releasability and degreasing property by using the nonpolar binder,
Since these binders lack affinity with the inorganic powder, the melt viscosity at the time of molding becomes high at a proper binder concentration, resulting in lack of fluidity, which is not particularly suitable for injection molding.

Therefore, when these binders are used, a dispersant for molding such as stearic acid, beeswax, and montanic acid ester is used together to disperse the inorganic powder, and a measure for smoothing the molding is taken.

However, even if these molding dispersants are used in combination, the effect of lowering the viscosity is not always sufficient, and improvement thereof has been strongly demanded.

Under the circumstances described above, the present invention has been achieved as a result of intensive studies to provide a molding dispersant capable of achieving a sufficient viscosity reduction even with a small amount of compounding and achieving smooth molding.

Means for Solving the Problems A molding dispersant in the production of a sintered body of the present invention is a molding dispersant to be blended with a binder in an inorganic powder during the production of a sintered body. -Hydroxy oleic acid or castor oil fatty acid, or 12-hydroxystearic acid or hydrogenated castor oil fatty acid;
And / or an ester (B) obtained by esterifying the carboxyl group or hydroxyl group of the intermolecular oligoester (A) with a non-oxycarboxylic acid type alcohol or acid. It is characterized by.

The present invention will be described in detail below.

As the inorganic powder in the present invention, any inorganic powder used as a raw material for a sintered body such as ceramics or powder metallurgy is used, and examples thereof include aluminum oxide (alumina), silicon oxide (silica), and zirconium oxide (zirconia). , Titanium oxide (titania), magnesium oxide (magnesia), beryllium oxide (beryllia), zinc oxide,
Vanadium oxide, tin oxide, chromium oxide, iron oxide, barium oxide, thorium oxide, uranium oxide, yttrium oxide, niobium oxide, plutonium oxide, indium oxide,
Oxides such as cerium oxide or complex oxides containing these oxides; nitrides such as silicon nitride, boron nitride, aluminum nitride, titanium nitride; silicon carbide, boron carbide, titanium carbide, zircon carbide, tungsten carbide, iron carbide , Carbides such as uranium carbide; ferrite, barium ferrite; lanthanum boride; iron, iron alloys, copper, copper alloys, aluminum, aluminum alloys, silicon, silicon alloys, nickel alloys, cobalt alloys, titanium alloys,
Examples include metals such as tungsten alloy, boron alloy, and stainless steel.

Among these inorganic powders, the metal oxides or complex oxides mentioned above are important, and especially alumina and zirconia are important.

As the binder, a nonpolar substance such as paraffin wax, microcrystalline wax, low molecular weight polyolefin (polyethylene wax or polypropylene wax) is used.

In the present invention, the intermolecular oligoester (A) or / and ester (B) described below is used as a molding dispersant together with the above-mentioned inorganic powder and binder in the production of the sintered body.

(A) Dimer or higher intermolecular oligoester of oxycarboxylic acid having 12 or more carbon atoms (B) Esterification of carboxyl group or hydroxyl group of the intermolecular oligoester (A) with alcohol or acid of non-oxycarboxylic acid type As the oxycarboxylic acid having 12 or more carbon atoms in the intermolecular oligoester (A), 12-hydroxyoleic acid (that is, ricinoleic acid) or this is used in view of its availability and performance as a molding dispersant. Castor oil fatty acid containing as a main component, or 12-hydroxystearic acid or hydrogenated castor oil fatty acid containing this as a main component is used.

The intermolecular oligoester of an oxycarboxylic acid having 12 or more carbon atoms (A) is obtained by reacting an oxycarboxylic acid having 12 or more carbon atoms in an inert gas atmosphere with or without a catalyst at a temperature of
It is obtained by reacting for a predetermined time while removing water produced at about 0 to 300 ° C, preferably about 160 to 250 ° C. The degree of condensation is the acid value of the reaction product, the hydroxyl value,
Alternatively, it can be determined by measuring the viscosity. The intermolecular oligoester (A) is a dimer or more for the purpose of the present invention,
Preferably, it is a trimer or more, and has 1 carbon atom.
With two or more oxycarboxylic acids (that is, a monomer), the viscosity cannot be sufficiently reduced even if they are used together with a binder.

The ester (B) is the above intermolecular oligoester (A).
It can be obtained by esterifying the carboxyl group or hydroxyl group of the above with a non-oxycarboxylic acid type alcohol or acid. Here, as the alcohol, butanol, hexanol, octanol, decyl alcohol, lauryl alcohol, cetyl alcohol, stearyl alcohol, oleyl alcohol, cyclohexanol, benzyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, di Propylene glycol,
Polypropylene glycol, butanediol, hexanediol, glycerin, diglycerin, polyglycerylene, trimethylolpropane, neopentyl glycol, pentaerythritol, sorbitol, sorbitan, etc. are used, and the acid is acetic acid, propionic acid, lauric acid, myristin. Acids, stearic acid, behenic acid, montanic acid, linoleic acid, linolenic acid, oleic acid, oxalic acid, maleic acid, adipic acid, maleic anhydride, phthalic anhydride, sebacic acid and the like are used. Esterification can be achieved by heating reaction in the absence of a catalyst or in the presence of a suitable catalyst according to a conventional method.

The blending amount of the binder and the molding dispersant with respect to the inorganic powder is not uniformly determined because it varies depending on the type of each component and the molding method, but in the case of injection molding or extrusion molding, the inorganic powder 100 The total amount of the binder and the molding dispersant is often 10 to 35 parts by weight with respect to parts by weight, and the ratio of the binder and the molding dispersant is 1 to 70 parts by weight of the molding dispersant with respect to 100 parts by weight of the binder. It is often the weight part. If the ratio of the binder and the molding dispersant to the inorganic powder is too small, molding cannot be performed smoothly, while if it is too large, degreasing takes an extremely long time and degreasing becomes difficult. Further, if the ratio of the molding dispersant to the binder is too small, the effect of improving the moldability is insufficient, while even if it is more than necessary, the effect of improving the moldability does not rise above the limit, and in some cases, the moldability is rather increased. May decrease, resulting in a cost disadvantage.

The inorganic powder, the binder, and the dispersant for molding may be mixed in three parts at the time of molding, but it is also possible to mix any two parts in advance and mix the rest. For example, a method of mixing a molding dispersant, an inorganic powder and a binder at the time of molding, a method of previously dissolving the molding dispersant in a binder, and mixing this with the inorganic powder at the time of molding, an inorganic powder with a molding dispersant. It is possible to employ a method in which surface treatment is performed and this is used as a ceramic powder. It is also possible to mix the molding dispersant with the binder in advance and to attach the molding dispersant also to the inorganic powder side.

Taking the case of injection molding or extrusion molding as an example of the production of a sintered body, a mixture of the above inorganic powder, binder and molding dispersant in a predetermined ratio is supplied to an injection molding machine or an extrusion molding machine and heated. The mixture may be kneaded into a mold and discharged into a mold or extruded to obtain a molded body, and the molded body thus obtained is gradually heated in a furnace for degreasing and then sintered at a predetermined temperature.

Action In the present invention, the intermolecular oligoester (A) or / and the ester (B) has the action of dispersing the inorganic powder in the state of being mixed with the inorganic powder and the binder, whereby the injection moldability and the extrusion moldability are obtained. Moldability such as is remarkably improved.

EXAMPLES Next, the present invention will be further described with reference to Examples. Hereinafter, "%" and "parts" are shown by weight.

Synthesis of molding aid Synthetic example 1 1200 g of hydrogenated castor oil fatty acid (main component is 12-hydroxystearic acid) was charged into a four-necked flask equipped with a stirrer, a cooling tube with a test tube, a nitrogen introducing tube and a thermometer. ,
At 215-225 ℃ while heating and stirring in a nitrogen stream.
The reaction was carried out for 10 hours. During this period, 51.0 ml of water of reaction was distilled off.

By the above reaction, a viscous liquid having an acid value of 34.8 and a hydroxyl value of 12.7 was obtained. The saponification value was 199.4 and the iodine value was 3.4.
This reaction product corresponds to a hexamer oligoester of hydrogenated castor oil fatty acid.

Synthesis Example 2 Using 1.2 g of p-toluenesulfonic acid as a catalyst and carrying out the reaction in the same manner as in Synthesis Example 1 except that the reaction time was 0.5 hours, a soft paste substance having an acid value of 62.7 and a hydroxyl value of 44.0 was obtained. . This reaction product corresponds to a trimer oligoester of hydrogenated castor oil fatty acid.

Synthesis Example 3 A four-necked flask equipped with a stirrer, a cooling tube with a test tube, a nitrogen introducing tube and a thermometer was charged with 1200 g of castor oil fatty acid (mainly 12-hydroxyoleic acid) and heated in a nitrogen stream. While stirring, the mixture was reacted at 215 to 225 ° C for 10 hours. During this period, 56.5 ml of water of reaction was distilled off.

By the above reaction, a viscous liquid having an acid value of 38.3 and a hydroxyl value of 9.9 was obtained. The saponification value was 201.7 and the iodine value was 95.1. This reaction product corresponds to a hexamer oligoester of castor oil fatty acid.

Synthesis Example 4 Using a mixture of 350 g of hydrogenated castor oil fatty acid and 350 g of castor oil fatty acid, reaction was carried out at 215 to 225 ° C. for 8 hours in accordance with Example 1 below. During this period, 26.0 ml of water of reaction was distilled off.

The obtained reaction product corresponds to a pentameric oligoester, which has an acid value of 38.8, a hydroxyl value of 15.0, and an iodine value of 49.2.
Met.

Synthesis Example 5 Using 403 g of hydrogenated castor oil fatty acid, a reaction was carried out for 2 hours in the same manner as in Synthesis Example 1, then the system was cooled to a temperature of 95 ° C., and 39 g of 70% sorbitol and 0.5 g of sodium hydroxide (catalyst) were added. In addition, heat gradually while distilling water 2
The temperature was raised to 15 to 225 ° C., and the reaction was further performed at this temperature for 5 hours.

By the above reaction, a viscous liquid having an acid value of 3.9 and a hydroxyl value of 70.6 was obtained. This reaction product corresponds to an ester obtained by reacting 1 molecule of sorbitol with 3 molecules of a trimer oligoester of hydrogenated castor oil fatty acid.

Synthesis Example 6 A flask was charged with 936 g of hydrogenated castor oil fatty acid and 280 g of stearic acid (3: 1 in molar ratio), and the mixture was gradually heated while distilling water to raise the temperature to 215 to 225 ° C. The reaction was carried out at this temperature for 5 hours. During this period, 37.0 ml of water was distilled.

By the above reaction, an opaque viscous liquid having an acid value of 70.8 and a hydroxyl value of 2.5 was obtained. This reaction product corresponds to an ester obtained by capping stearic acid on the hydroxyl groups of a hydrogenated castor oil fatty acid oligoester.

Synthesis Example 7 624 g of hydrogenated castor oil fatty acid and 560 g of stearic acid (molar ratio of 1: 1) were charged into a flask and gradually heated while distilling water to raise the temperature to 215 to 225 ° C. The reaction was carried out at this temperature for 5 hours. During this time, 24.0 ml of water was distilled off.

In this reaction, the reaction rate of hydrogenated castor oil fatty acid is higher than that of stearic acid esterification.

A solid having an acid value of 110.8 and a hydroxyl value of 0 was obtained by the above reaction. This reaction product corresponds to an ester obtained by capping stearic acid on the hydroxyl groups of a hydrogenated castor oil fatty acid oligoester.

Viscosity of Molding Composition Hereinafter, the molding dispersant of Comparative Examples is as follows.

Comparative Example 1 Beeswax Comparative Example 2 Stearic Acid Comparative Example 3 12-Hydroxystearic Acid Comparative Example 4 12-Hydroxyoleic Acid Comparative Example 5 Montanic Acid Ethylene Glycol Ester Viscosity Measurement Example 1 Alumina (Alumina A-32, 2μ manufactured by Nippon Light Metal Co., Ltd.) 160 g of a 62.5% pass) and 32 g of paraffin wax (130 ° F) as a binder are added with a molding dispersant whose type and amount are shown in Table 1 and mixed well.
The viscosity at 90 ° C. was measured using a B type viscometer.
However, if it is over 10,000 cps, use No. 4 rotor and 12 rp
When the m was less than 10,000 cps, the measurement was performed at 12 rpm using a No. 3 rotor.

The results are shown in Table 1.

Viscosity measurement example 2 160 g of alumina (used in viscosity measurement example 1) and 32 g of paraffin wax (130 ° F) as a binder
A molding dispersant having the type and blending amount shown in Table 2 was added thereto and mixed well, and the viscosity at 90 ° C. was measured using a B-type viscometer.

The results are shown in Table 2.

Viscosity measurement example 3 Zirconia (Partially stabilized zirconia HSY-3.0 manufactured by Daiichi Rare Element Chemical Co., Ltd., specific surface area 6.4 m ² / g) 160 g and paraffin wax (130 ° F) 32 g as a binder
Then, the molding dispersant whose type and blending amount are shown in Table 3 was added and mixed well, and the viscosity at 90 ° C. was measured using a B-type viscometer.

The results are shown in Table 3.

Viscosity measurement example 4 160 g of alumina (the one used in viscosity measurement example 1) and 32 g of microcrystalline wax (Hi-Mic-1080 manufactured by Nippon Seiro Co., Ltd., melting point 84 ° C.) as a binder are shown in Table 4 with the types. The molding dispersant having the compounding amount was added and mixed well, and the viscosity at 120 ° C. was measured using a B-type viscometer.

The results are shown in Table 4.

Viscosity measurement example 5 160 g of alumina (the one used in viscosity measurement example 1) and 32 g of an equal weight mixture of paraffin wax (130 ° F) as a binder and low molecular weight polyethylene (Sun wax 171-p manufactured by Sanyo Kasei Co., Ltd.) In addition, a molding dispersant having the type and amount of compound shown in Table 5 is added and mixed well,
The viscosity at 150 ° C. was measured using a B type viscometer.

The results are shown in Table 5.

Viscosity Measurement Example 6 A mixture of 160 g of alumina (used in Viscosity Measurement Example 1), paraffin wax (130 ° F) xg as a binder and 4 g of the molding dispersant of Synthesis Example 1 was mixed well and
The viscosity at 90 ° C. was measured using a B type viscometer.

The results are shown below.

x = 21 35200 cps / 90 ° C x = 23 11150 cps / 90 ° C x = 25 4430 cps / 90 ° C x = 30 1140 cps / 90 ° C Viscosity measurement example 7 Alumina (used in viscosity measurement example 1) yg, binder 32g of paraffin wax (130 ° F) and 4g of the molding dispersant of Synthesis Example 1 were mixed well, and 90
The viscosity at ° C was measured using a B-type viscometer.

The results are shown below.

y = 140 650 cps / 90 ° C y = 180 3650 cps / 90 ° C y = 200 10500 cps / 90 ° C y = 210 21850 cps / 90 ° C y = 220 35650 cps / 90 ° C Sintered body manufacturing example 1 To 160 parts of alumina (the one used in viscosity measurement example 1) and 32 parts of paraffin wax (130 ° F) as a binder, 2 parts of the molding dispersant of Synthesis example 1 was added and mixed well, and this mixture was mixed. Injection molding was performed under the conditions of a cylinder temperature of 100 ℃, injection pressure of 5kg / cm ² and mold temperature of 40 ℃.
30 compacts of × 50 × 50 mm were obtained, which were then placed in a furnace, gradually heated to 500 ° C. for degreasing, and the weight thereof was measured to determine the degree of degreasing.

After degreasing, this molded body was sintered at 1750 ° C., and the properties of the sintered body were observed.

The results were as follows.

Good injection moldability Degree of degreasing Residual organic matter 1% or less Properties of sintered body No defects (cracks, strains, holes) in all 30 sintered body In addition, the same favorable results were obtained when the molding dispersant of other synthesis examples was used. was gotten.

Sintered body production example 2 To 160 parts of zirconia (used in viscosity measurement example 3) and 32 parts of paraffin wax (130 ° F) as a binder, 2 parts of the molding dispersant of Synthesis example 1 was added and mixed well. Then, using this mixture, injection molding, degreasing and sintering were performed in the same manner as in Sintered body manufacturing example 1. However, the sintering temperature is 1550 ℃
And

The results were as follows.

Good injection moldability Degree of degreasing Residual organic matter 1% or less Properties of the sintered body No defects (cracks, holes, strains) in all 30 Effects of the Invention By adding a small amount of the molding dispersant of the present invention to an inorganic powder and a binder. The viscosity during heating is reduced, and the moldability is remarkably improved. When this molded body is degreased and sintered, it is sufficiently degreased, and the obtained sintered body is of high quality with no defects.

Therefore, the present invention greatly contributes to the field of ceramics or powder metallurgy.

Claims (3)

[Claims] 1. A molding dispersant which is mixed with an inorganic powder together with a binder made of a non-polar substance in the production of a sintered body, wherein the molding dispersant is 12-hydroxyoleic acid or castor oil fatty acid or 12-hydroxy. Dimer or higher intermolecular oligoester (A) of oxycarboxylic acid having 12 or more carbon atoms selected from stearic acid or hydrogenated castor oil fatty acid, and / or carboxyl group of the intermolecular oligoester (A) or A dispersant for molding in the production of a sintered body, which comprises an ester (B) obtained by esterifying a hydroxyl group with a non-oxycarboxylic acid type alcohol or an acid. 2. The molding dispersant according to claim 1, wherein the inorganic powder is a metal oxide or a metal double oxide. 3. The molding according to claim 1, wherein the binder made of a non-polar substance is at least one non-polar substance selected from the group consisting of paraffin wax, microcrystalline wax and low molecular weight polyolefin. Dispersant.