JPH02307861A - Binder for ceramic green tape and production of green tape using the binder - Google Patents

Abstract

PURPOSE:To produce the binder to be used in the production of a uniform high-density ceramic green tape excellent in smoothness by preparing a hydrophobic modified polyurethane having a structure shown by a specified formula and with the mol.wt. of the polymer specified. CONSTITUTION:An appropriate polyether diol, a reactive compd. having a hydrophobic group and a diisocyanate are polymerized to obtain the binder consisting of a hydrophobic modified polyurethane having a structure shown by the formula and with the mol.wt. of the polymer controlled to >= at least 10,000. In the formula, X is a polyether diol residue having 200-50,000mol.wt., R2 is a bivalent org. residue derived from a diisocyanate compd., A and B are independently OH or a 1-18C monoisocyanate residue, Z is the residue of a compd. having a functional group capable of reaching with >= at least 8C alkyl group or aromatic alkyl group and diisocyanate group, and n and m are an integer of >=1. As a result, a binder capable of producing a stabilized-quality ceramic green tape is obtained.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a ceramic green tape binder and a method for manufacturing ceramic green tape using the binder.

[Conventional technology]

The conventional manufacturing method for ceramic green tape is 1. For example, a binder such as butyral resin or poly(meth)acrylic acid ester is dissolved in an organic solvent such as methyl ethyl ketone, and a ceramic raw material fine powder is mixed with this and mixed for a long time. After defoaming, the material is poured out of a knife called a doctor knife, and then formed into a sheet on a carrier film, which is then heated and dried. However, due to the use of organic solvents in this conventional manufacturing method, there are problems such as harm to human health, odor pollution, and the risk of explosion. Recently proposed manufacturing methods to solve this problem include a method in which a water-soluble or water-dispersible organic binder such as polyvinyl alcohol or polyvinyl acetate resin is used as the moss of the oil-soluble binder; Showa 55-1136
A method of using water-based polyurethane as a binder as described in Publication No. B5, and also a method of using JP-A-58-11
There are various manufacturing methods, such as a method using a combination of water-based polyurethane and water-soluble acrylic resin as a binder as described in Japanese Patent No. 10887.

[Invention tries to solve! Title】

However, in such a conventional manufacturing method using polyvinyl alcohol as a binder, it is difficult to obtain a high-density, smooth green tape because the viscosity of the aqueous slip deviates significantly from Newtonian flow. In addition, although the production method using water-based polyurethane as a binder can solve the above-mentioned drawbacks to some extent, it is still insufficient from the viewpoint of viscosity characteristics suitable for coating. That is, as a viscosity behavior suitable for the coating production of green tape, Newtonian flow with a rather thixotropic property is desired, as shown by conventional solvent-based slip coating liquids. For example, Newton 11. As a measure of dynamic properties, slip viscosity is measured using a B-type viscometer and calculated as the ratio of the viscosity value (A) at 10 rpm and the viscosity value (B) at 50 rpm (A/B).
) is expressed as a thixoscopic ratio, the value of this ratio is 1.2
When it is 1.6, the most suitable coating property is exhibited, and a uniform, high-density, smooth green tape can be obtained. No conventionally known aqueous binder has been developed that meets these requirements. Furthermore, when water-based polyurethane is used as a binder, the moisture contained in the ceramic green tape is affected by the environmental humidity during the manufacturing process, which affects the physical properties such as strength and density of the green tape, and ultimately the ceramic sintered body. There is a problem in that the density affects the stability of one dimension, making it difficult to obtain a uniform product. The present invention has focused on the above-mentioned problems in the prior art, and aims to provide a new ceramic green tape binder that does not have the above-mentioned drawbacks and a method for manufacturing a ceramic green tape using the same.

[Means to solve the problem]

The present invention has a structure represented by the following general formula (I),
The ceramic green tape binder is characterized in that it is made of hydrophobically modified polyurethane (hereinafter referred to as hydrophobically modified polyurethane) and the molecular weight of the polymer is at least 10,000, and the binder thereof is used. This is a method for manufacturing ceramic green tape. The hydrophobically modified polyurethane used in the present invention is obtained by polymerizing a suitable polyether diol, a reactive compound containing a hydrophobic group, and a diisocyanate. Polyether diol that can be used here; 110- (
C112-(:H-0-) p-11 (in the formula, R1 is hydrogen or an alkyl group having 1 to 2 carbon atoms; it may be present alone or in combination in the molecule; P is !!I! number) A diol having a polyoxyfulkylene group consisting of a C2 to C4 oxyalkylene group and having a molecular weight of 20
0 to 50,000, more preferably 300 to 20,000
Preferably. It is preferable that the polyether diol contains 20% or more of oxyethylene groups, and if the oxyethylene group content is less than 20% by weight, the resulting polyurethane is difficult to be water-soluble, and the present invention cannot fully demonstrate its effectiveness. Moreover, the polyether diol content in the hydrophobically modified polyurethane of the present invention is preferably 70 to 89% by weight, more preferably 80 to 98% by weight! It is ^%. Even when the water content is less than 70% by weight, the polyurethane obtained is difficult to become water-soluble, and the first objective of the present invention cannot be achieved. A reactive compound containing a hydrophobic group; R2 is an alkyl group or an aromatic alkyl group having at least 8 carbon atoms. W is bonded to R2 via a carbon-carbon bond, carbon-nitrogen bond, ether bond, 1,000-onythyl bond, or amide bond. The organic residue (preferably a molecular weight of 300 or less) is selected from compounds containing at least an alkyl group having carbon a8 or more, an aromatic alkyl group, and a functional group capable of reacting with an incyanate group. Some specific examples include (1) 1.2-octene oxide, 1.2-dodecene oxide, 1.2-
1,2-epoxides, such as hexadecene oxide and 1,2-octadecene oxide, (2) 1.2-
octanediol, 1.2-decanediol, 1.2-
Dodecanediol, 1,2-tetradecanediol, 1
．． 2-hexadecanediol, 1, 2-year old ctadecanediol; 1. 2-diicosandiol; l, 3-nonanediol: diethylene glycol and 1,2-octene oxide, l. Reaction products of nilauryl alcohol or cetyl alcohol with alkylene oxides such as 2-dodecene oxide, 1,2-hexadecene oxide or 1,2-octadecene oxide and 1,2-dodecene oxide or 1.2 −
Reaction products with hexadecene oxide: as well as polyoxyalkylation reaction products of the above compounds, as well as vinyl polymers obtained by radical polymerization using glycerin hexadecanoic acid monoester, glycerin hexadecanol monoether, and thioglycerin as chain transfer agents. Alkyl or inalkyl 1,2-diols and 1,3-diols such as coalesced oligomers; (3) Alkenes such as 1-dodecene, 1-tetradecene and l-hexadecene; (4) 1. diamines such as 2-diaminodecane; and (5) dicarboxylic acids such as laurylmalonic acid and octylsuccinic acid. These hydrophobic group-containing reactive compounds may be used alone, or may be used in combination as appropriate. For the purpose of the present invention, reactive compounds having a hydrophobic group that are particularly preferably used include 1,2-hexadecanediol, and reaction products of diethylene glycol and 1,2-hexadecene oxide. The reactive compound containing the hydrophobic group in 1 above is the Il of the present invention.
It is an essential component to achieve the effect of 1. A suitable amount thereof is 0.01 to 20% by weight in hydrophobically modified polyurethane, preferably 0.1 to 1037% by weight, most preferably 0.5 to 5% by weight. If it exceeds this, it will no longer dissolve in water, and the effect of unreleased IJ1 will not be exerted on the viscosity of the slip. Diisocyanate is: 0=C-N-Rs -N-C; -Q (wherein, R1 is unsubstituted or halo, alkyl and /x are alkylene, cycloalkylene or arylene substituted with substituents such as aryl groups. Some representative examples of such compounds are: 2.6 −
and 2,4-tolylene diisocyanate, bis(4-incyanatophenyl)-methane (i.e., methylene dianiline diisocyanate), l-isocyanato-3-incyanatomethyl-3,5,5-)limethylcyclohexane (i.e., isophorone). diisocyanate)), 1,4-tetramethylene diisocyanate, 1゜6-hexamethylene diisocyanate, 2,2,4-trimethyl-1,8-
Diisocyanatohexane, 1,10-decamethylene diisocyanate, 1,4-cyclohexylene diisocyanate, bis(4-incyanatocyclohexyl)methane, m- and p-phenylene diisocyanate, 4-chloro-1,3-phenylene diisocyanate, Examples include 1.5-naphthalene diisocyanate, 1.5-tetrahydronaphthalene diisocyanate, and mixtures thereof. However, particularly preferred diisocyanates for the purpose of the invention are tolylene diisocyanate, inphorone diisocyanate and methylene dianiline diisocyanate. The desired molecular weight of the hydrophobically modified polyurethane is at least 10,000, preferably from 10,000 to ioo. 000 most preferably between 25,000 and 500,000. Further, the hydrophobically modified polyurethane may be produced by either a stepwise production method or a batch production method. As a method of stepwise preparation, for example, a pre-dehydrated polyether diol, a diincyanate in an amount slightly less than the number of moles of the polyether diol, an inert solvent, and a catalyst are charged into a reaction vessel, and the mixture is heated under a nitrogen stream for 50 to 50 minutes. React at a reaction temperature of 120°C until there is no remaining incyanate,
An intermediate with a terminal OH group is synthesized. Next, a reactive compound containing a hydrophobic group is charged, followed by a diincyanate compound necessary and sufficient to achieve the desired molecular weight, and the urethanization reaction is terminated at 50 to 120°C (until there is no remaining incyanate). ). At this time, a catalyst may be added if necessary. Alternatively, contrary to the above, a reactive compound containing a hydrophobic group may be first reacted with a diisocyanate and then reacted with a polyether diol to form a urethane. Furthermore, the reaction product may be end-capped with an alkyl monoisocyanate, and then, if necessary, the solvent is distilled off to obtain a reaction product. On the other hand, as for the production method by batch charging, polyether diol, a reactive compound containing a hydrophobic group, and diisocyanate necessary and sufficient to obtain the desired molecular weight are charged in an inert solvent, and if necessary, Using a catalyst, the reaction is carried out at 50 to 120° C. under a nitrogen stream until the urethanization reaction is completed. In this case as well, after completion of the reaction, end capping is performed with an alkyl monoisocyanate, if desired, and then, if necessary, the solvent is distilled off to obtain a reactant. The structure of the obtained reactant is a polymer in which polyether moieties and reactive compound moieties containing hydrophobic groups are bonded in unevenly distributed blocks in the stepwise charging method, whereas in the batch charging method, It is a randomly bonded polymer. In the above reaction, if the reaction temperature is less than 40°C, the reaction rate is slow and it takes time to complete. On the other hand, if the reaction temperature is 1
When the temperature is higher than 20°C, abnormal side reactions occur. Preferably, the temperature is within the range of 70 to 80°C. In this reaction, the solvent used as necessary is a solvent that does not contain active hydrogen, for example, aromatic solvents such as toluene and xylene, and aliphatic solvents such as petroleum ether and n
-For alicyclic solvents such as hexane, cyclohexane,
For halogen-containing solvents such as cyclohexanone and decalin, chloroform, carbon tetrachloride, ethylene dichloride,
Ester solvents such as chlorobenzene include ethyl acetate, butyl acetate, pentyl butyrate, and the like; ketone solvents include methyl ethyl ketone, diethyl ketone, and methyl isobutyl ketone. Furthermore, catalysts used in urethanization reactions, such as amine compounds such as triethylamine, triethylenediamine, heptamethyldiethylenetriamine, N-methylmorpholine, and benzyltriethylammonium hydroxide, and metal-containing compounds such as stannous chloride and stannic chloride. , tin octylate, lead octylate, dibutyltin dilaurate, cobalt naphthenate, lead naphthenate,
Potassium naphthenate, tetra(2-ethylhexyl) titanate, sodium 〇-phenylphenate, potassium oleate, antimony trichloride, etc. are used as necessary. The amount of catalyst added is from 0.1 to the total active hydrogen component charged.
It is preferably 0.1 to 700 PP. These catalysts are usually added at the beginning of the reaction, but may be added in portions during the reaction. The ceramic green tape binder of the present invention has such a hydrophobically modified polyurethane as its main component, and the method for producing the ceramic green tape using the binder includes ceramic raw material fine powder, the binder of the present invention, water, and Add a dispersant and antifoaming agent to the ball mill if necessary. Next, a pole is inserted and the wires are crossed, and the resulting slip is flowed out from a knife called a doctor, and is received by a carrier film and moved while drying to form a tape. The amount of the binder of the present invention added is 1 part of the ceramic raw material fine powder.
00 parts by weight, the resin content is 3 to 15 parts by weight, preferably 7 to 12 parts by weight. If the amount added is less than 3 parts by weight, the amount of binder will be insufficient, and the resulting green tape will be prone to cracking.
If the amount exceeds 15 parts, the density of the green tape and the resulting sintered body will not increase, which is not preferable. The ceramic raw material fine powder to which the binder is added is, for example, alumina, silicon carbide, silicon nitride, zirconia,
Cordierite, Rishi7 ceramic, thorium oxide, hafnium carbide, barium titanate, lead zirconate titanate, zeolite, magnesia, beryllia, boron nitride, tin oxide, aluminum titanate, zinc oxide, mullite,
Sialon etc. In addition, when actually adding the binder of the present invention,
As mentioned above, known dispersants and antifoaming agents, as well as known surfactants, plasticizers, water-soluble solvents, and the like may be used in combination as appropriate.

[Effect]

The ceramic green tape binder and the ceramic green tape manufacturing method using the binder of the present invention provide the following effects. ■Produces slip with Newtonian fluidity suitable for coating during ceramic green tape production. It is currently unclear why the product of the present invention exhibits Newtonian fluidity in a slip, but it is probably due to the hydrophobic groups in the hydrophobically modified polyurethane forming a bond between hydrophobic groups.
Or it is presumed to be the result of interaction with ceramic powder. ■Produces a high-density green tape with uniformity and excellent smoothness. ■The moisture content of the obtained green tape is not affected by the humidity of the atmosphere, making it possible to produce ceramic green tape of stable quality. This has the advantage that it can be produced using the same manufacturing method even under conditions where the relative humidity is significantly different in summer and winter.

【Example】

The invention will be explained in more detail with reference to the following production examples and test examples, but the examples are merely for illustration purposes and are not intended to limit the connotation or extension of the inventive idea. Hereinafter, the abbreviations of the compounds used in the production examples are collectively shown in the table below. Production Examples 1 to 6 These production examples describe a method for producing hydrophobically modified polyurethane by batch charging. Made in "L example" PE for thermometer, stirrer, nitrogen introduction tube, and water test tube with cooling tube
Gs. . . 1000g Ct s diol 6.0g
1900 g of toluene was charged and refluxed under a nitrogen stream to azeotropically remove contaminating wood. Then, the reaction solution was cooled to 80°C, and DBTL 200P
After adding Pm, 32.8 g of IPDI was added, and the reaction was continued until the urethanization reaction was completed (until there was no remaining incyanate). Thereafter, the reaction product was taken out into a shallow dish, and the toluene was evaporated in an oven to obtain the desired hydrophobically modified polyurethane. In the same manner as in Production Example 1, a hydrophobically modified polyurethane shown in Table fjS1 was obtained. The following manufacturing example describes a stepwise method for making virgin IJ1 hydrophobically modified polyurethane. 1! In a reactor similar to that described in Production Example 1 above, PE01
゜. . . 1000. and toluene looog were charged and refluxed under a nitrogen stream to remove contaminating water.Next, the reaction solution was cooled to 60°C and heated to DBTL.
After adding 200 ppm, 18.9 g of TOI was added dropwise, and the reaction solution became viscous in 2 to 3 hours. The remaining incyanate was almost gone. To the above intermediate reaction product, 41.5 g of C11i diol was added, followed by dropwise addition of 30.3 g of TOl, and the urethanization reaction was carried out at 80° C. for 2 hours, and then heated to 80° C. until there was no remaining incyanate. carried out. Thereafter, the reaction product was taken out into a shallow dish, and toluene was evaporated in an oven to obtain a hydrophobically modified polyurethane similar to L1. Hydrophobically modified polyurethanes shown in Table 2 were obtained in the same manner as in Production Example 7. Example. Alumina (low soda alumina; AfL203, purity 99
．． An alumina slip composition containing a binder, a dispersant, an antifoaming agent, and water in the proportions shown in the ff5a table was placed in an alumina ball mill, and then the amount of alumina was 3 times the amount of ff<m. An alumina ball mill was used to mix the mixture for 24 hours. After defoaming, measure the viscosity of the slip using a B-type viscometer. The viscosity ratio between 10 rpm and 5 Orpm was determined as the thixotropic ratio. Further, this slip was formed into an alumina slurry sheet (green tape) of approximately 100 mL on a polyester sheet using a doctor blade method. This was dried according to a conventional method, and the density of the green tape was measured, and the water absorption rate during storage for 24 hours at 25° C. and 60% RH or 90% RH was determined in terms of weight increment. Next, this was fired at tsoo°C, and then the apparent specific gravity and surface roughness were measured. The results obtained are shown in Table 3.

【Effect of the invention】

As mentioned above, the binder for ceramic green tape of Unexploited +51 and the method for manufacturing ceramic green tape using the same include: ■ A slip with Newtonian fluidity suitable for coating during the production of ceramic green tape can be obtained. ■ A high-density green tape with uniformity and excellent smoothness can be obtained. ■ The moisture content of the obtained green tape is not affected by the humidity of the atmosphere. ■ It is possible to produce a ceramic green tape of stable quality without being affected by the humidity of the atmosphere.11 It can contribute to related industries due to its advantages such as:

Claims (2)

[Claims] 1. A binder for a ceramic green tape, comprising a hydrophobically modified polyurethane having a structure represented by the following general formula (I) and a polymer having a molecular weight of at least 10,000. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) In the formula, X is a residue of polyether diol with a molecular weight of 200 to 50,000, R_3 is a divalent organic residue derived from a diisocyanate compound, and A and B are each independently OH or a monoisocyanate residue of C_1 to C_1_8, Z is a residue of a compound having at least an alkyl group having 8 or more carbon atoms or an aromatic alkyl group and a functional group that can react with an isocyanate group, n and m are 1 or more integer. 2. A method for producing a ceramic green tape, comprising using the binder according to claim 1.