JPH024548B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD This invention relates to moldable ceramic compositions, particularly compositions in which the ceramic component is a dielectric material. BACKGROUND OF THE INVENTION Multilayer capacitors are most widely used in ceramic capacitors for thin film hybrid microelectric systems due to their high volumetric efficiency and resulting small dimensions. These capacitors are manufactured by stacking ceramic substrate thin plates with appropriate electrode patterns printed on their surfaces and firing them.
Each electrode pattern layer is formed so as to be exposed alternately at each edge of the assembly. The exposed ends of the electrode pattern are coated with a conductive material to connect all layers,
Groups of capacitors connected in parallel are thus formed in the layered structure. This type of capacitor is often referred to as a monolithic capacitor. Thin sheets of ceramic substrate used in the manufacture of multilayer capacitors are usually called "green tape"
It contains a thin layer of fine dielectric particles interconnected by an organic polymeric material. Green tape is made by slipcasting a slurry of dielectric particles dispersed in a solution of polymer, plasticizer, and solvent onto a carrier such as polypropylene, Mylar® polyester film, or stainless steel. The thickness of the formed film is then adjusted by passing a forming slurry under a doctor blade. TiO ₂ − glass, (BaSr)TiO ₃ , (Ba, Pb)
TiO ₃ − glass, PbZrO ₃ TiO ₃ −BaTiO ₃ −Pb monosilicate glass, BaTiO ₃ Bi ₂ O ₃ , ZnO,
BaTiO ₃ −Cd borosilicate glass, BaTiO ₃ −
A wide range _of capacitor materials can be made by the above method, including _{BaAl2 - SiO8 , BaTiO3- Pb2Bi4Ti5O18} and many others. Traditionally, various polymeric materials have been used as binders for green tapes; such as poly(vinyl butyral), poly(vinyl acetate), poly(vinyl alcohol); methylcellulose, ethylcellulose, hydroxyethylcellulose, methylhydroxyethylcellulose. cellulosic polymers such as attacking polypropylene, polyethylene; silicone polymers such as poly(methylsiloxane), poly(methylphenylsiloxane); polystyrene, butadiene/polystyrene copolymers, poly(vinylpyrrolidone),
polyamides, high molecular weight polyethers, copolomers of ethylene oxide and propylene oxide;
polyacrylamide; and various acrylic polymers such as sodium polyacrylate, poly(lower alkyl acrylate), poly(lower alkyl methacrylate), and copolymers and multipolymers of lower alkyl acrylate and methacrylate. Copolymers of ethyl methacrylate and methyl acrylate and terpolymers of ethyl acrylate, methyl methacrylate and methacrylic acid have previously been used as binders for slip molding materials. Mainly due to technical reasons for slip molding equipment, the ceramic dispersion system (slip) for molding dielectric films is 100~400cp, preferably 500~400cp.
The viscosity is within the viscosity range of 3000 cp (Brutskfield LVT viscometer No. 2 spindle, 6 rpm, 25°C). Within these viscosity limits, it is preferred to use a molded slip containing the highest content of ceramic material and the lowest content of polymeric binder and solvent. By this method, the amount of material that must be removed by pyrolysis can be kept to a minimum and problems with delamination of the layers are also reduced. To date, a persistent problem has been that the viscosity of polymers that have a high enough molecular weight to provide suitably durable tapes and require the use of relatively small amounts of binder has been too high. High viscosity polymers are critical in limiting the amount of dielectric solid that can be used. It also increases the ratio of organic material to dielectric solid, resulting in more organic material having to be thermally decomposed. On the other hand, low molecular weight polymers which have a suitably low viscosity and can therefore contain higher amounts of dielectric solids provide only very brittle layers. Arrangements of the Invention The above-mentioned drawbacks of the rheological properties of conventional ceramic suspensions used as molding slips are substantially overcome by the present invention. The present invention comprises: (a) finely divided particles of a ceramic solid; (b) 0-100% by weight of a C1-8 alkyl methacrylate; 100-0% by weight of a C1-8 alkyl methacrylate;
and (c) a non-aqueous organic solvent. The above multipolymer has a number average molecular weight (Mn) of 50000
~100000, weight average molecular weight (Mw) ~150000
350000 and the ratio of Mw to Mn is not greater than 5.5, and the total amount of unsaturated carboxylic acid or amine in the multipolymer mixture is 0.2 to 2.0% by weight, and the polymer and, if present,
The glass transition temperature of the plasticizer is -30°C to +45°C. Additionally, the present invention provides a green method comprising casting a thin layer of the composition on a flexible substrate, such as a steel belt or a polymeric film, and heating the thin layer to remove volatile solvents therefrom. This invention relates to a method for manufacturing a tape. Furthermore, the present invention provides a capacitor manufactured by laminating and firing the green tapes described above, each of which has a suitable electrode pattern formed on its surface by an offset method or the like. The ends of the electrodes are formed so as to be exposed alternately from opposite edges of the laminated structure, and the exposed ends are electrically connected by a conductive coating. Detailed Description of Construction A Ceramic Solid The present invention is applicable to virtually any high melting point inorganic solid material. However, it is particularly suitable for the production of moldable dispersions of dielectric solids such as titanates, zirconates and stannates. It is also applicable to precursors of such materials, ie solid materials that are converted to dielectric solids and any mixtures thereof upon calcination. When the composition of the invention is used for slip molding, the particle size does not exceed 15 μm, preferably 5 μm.
It is preferable not to exceed. On the other hand, particles are 0.1μm
Preferably no smaller. To obtain even stronger characteristics, the surface area of the particles should be at least 1 m ² /
g, preferably 4 m ² /g. Surface area 3-6
It has been found that particles of m ² /g are quite satisfactory for most applications. Even larger areas, e.g. 10m ² /
Particles of 1.5 g or more can be used, but must be weighed against the fact that larger surface areas require more organic medium to obtain a given dispersion viscosity. For this reason, the particles preferably have an average surface area of 3 to 8 m ² /g. Among the many dielectric solids that can be used in the present invention are, for example, BaTiO ₃ , CaTiO ₃ , SrTiO ₃ ,
PbTiO ₃ , CaZrO ₃ , BaZrO ₂ , MnO, Fe ₂ O ₃ , alumina, silica and various glass frits,
CaSnO ₃ , BaSnO ₃ , Bi ₂ O ₃ , BiTiO ₃ , BiSnO ₃ ,
These include kyanite, mullite, holsterite and zircon. The present invention is also very useful as a binder for loaf-eye dielectric materials such as those disclosed in Bouchard US Pat. Nos. 4,048,546 and 4,228,482. It is desirable that the ceramic solid have no swelling properties in the organic dispersion. This is because swelling substantially changes the rheological properties of the dispersion. B Polymer binder As described above, the binder components of the dispersion system of the present invention are 0 to 100% by weight of alkyl methacrylate having 1 to 8 carbon atoms, 100 to 0% by weight of alkyl methacrylate having 1 to 8 carbon atoms
alkyl acrylate and 0 to 5% by weight of an ethylenically unsaturated carboxylic acid or amine, the multipolymer having a number average molecular weight (Mn) of 50,000 to 100,000 and a weight average molecular weight (Mw) of 150,000 to 350,000, the ratio of Mw to Mn is 5.5 or less, the total amount of unsaturated carboxylic acids or amines in the multipolymer mixture is 0.2 to 2.0% by weight, and the plasticity of the polymer and, if present, It is further characterized in that the glass transition temperature is -30°C to +45°C. The above polymers are random copolymers and include terpolymers and higher multipolymers as long as the three basic comonomers are used in proportions within the above ranges. The relative amounts of the carboxylic acid or amine distributed along the polymer chain are very important. In particular, it has been found that in order to obtain a suitable dispersibility of the ceramic solids, at least 0.2% by weight of the monomer containing the above-mentioned functional moieties in the polymer mixture is required, and preferably at least 0.5% by weight is present. On the other hand, to prevent agglomeration of the dispersed ceramic solids, the above comonomers containing functional moieties can be present at 5.0% by weight of any polymer or 2.0% by weight in the polymer mixture.
It is necessary not to exceed. 1.8 in some cases
Several instances have been observed where polymer mixtures containing % acid-containing monomers were borderline or even unsatisfactory with respect to dispersion properties. Many of these examples still allow such polymers to be used in the present invention by using more polar solvents. Therefore, the functional group-containing monomer
Polymer mixtures containing up to 2.0% can be used, but
Polymer mixtures containing about 1.5% of functional monomers are preferred. More preferably, such functional monomer does not exceed 1.0% by weight. For similar reasons, any polymer contained in a polymer mixture
Preferably, it does not contain more than 5.0% by weight of functional monomer. Furthermore, in order to obtain adequate dispersibility, it is preferred that neither polymer contain less than 0.2% by weight of functional monomer. Thus, a polymeric binder is a mixture of polymers, some of which do not contain any functional moieties, and some of which contain no functional moieties, as long as the content of functional comonomer in this total mixture is in the range 0.2 to 2.0% by weight. The material would contain 5.0% by weight of functional comonomer. That said, polymer binders range from 0.2 to
Preferably, it consists entirely of an acrylic polymer as described above containing 2.0% by weight of functional comonomer. In any case, all polymers constituting the polymer binder must be compatible. This means that when the solvent is removed from a solution of the polymer in a co-solvent, a clear transparent film is formed. That is, the polymer mixture is single phase. Suitable copolymerizable carboxylic acids include ethylenically unsaturated C _3-6 monocarboxylic acids, such as acrylic acid,
methacrylic acid and crotonic acid; and C _4-10 dicarboxylic acids such as fumaric acid, itaconic acid, citraconic acid, vinylsuccinic acid and maleic acid; and their half esters and, where appropriate, their anhydrides and mixtures thereof. , such monomers constitute at least 0.2% and preferably at least 0.5% by weight of the polymer. Of course, the amine component is not directly incorporated into the chain by copolymerization of the amine-containing monomer, but indirectly by the post-polymerization reaction of the side-chain reactive portions of the polymer chain. This is evidenced by the addition of primary amines by reaction of side chain carboxylic acid groups with glycidyl compounds in the presence of ammonia. Thus, as used herein, the term "ethylenically unsaturated amine" is meant to include polymers derived from amine-containing comonomers as well as other comonomers that form amine groups in post-polymerization reactions. . Primary, secondary and tertiary amines are each equally effective. Comonomers suitable for adding side chain amine groups directly into the binder polymer chain include diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, and t-butylaminoethyl methacrylate. Suitable monomers that provide side chain functionality suitable for post-polymerization reactions that provide amine functionality include the ethylenically unsaturated epoxides described above, such as glycidyl acrylate or glycidyl methacrylate. It is possible for the polymeric binder of the invention to contain up to 100% by weight of acrylic or methacrylic monomers. Nevertheless, within the above ranges for these monomers, the alkyl methacrylate accounts for 40-80% by weight of the copolymer and the alkyl methacrylate accounts for 60-80% by weight of the copolymer.
Preferably it constitutes 20% by weight. The weight ratio of alkyl methacrylate to alkyl acrylate is preferably 1.5 to 2.5:1, particularly preferably 1.5 to 2.0:1. The polymeric binder can contain up to about 10% by weight of the acrylic and acidic comonomers described above, such as styrene, acrylonitrile, vinyl acetate, acrylamide, etc., as long as the compositional criteria described above and the physical criteria described below are met. However, it is preferred that such monomers be used at less than about 5% by weight. It is currently unknown whether the use of such other comonomers adds anything to the efficacy of the copolymers used in this invention. However, such comonomers in the above-mentioned limited amounts do not reduce the effectiveness of the polymer as long as all compositional and physical criteria are met. In addition to the compositional factors mentioned above, it has been observed that the physical factors of the polymeric binder have a completely unexpected importance in the compositions of the present invention. In particular, the weight average molecular weight (Mw) and number average molecular weight (Mn) of the polymer and the ratio of these two properties must be limited within narrow limits to obtain the advantages of the present invention. In order to obtain sufficient strength, the polymer binder must have a number average molecular weight within the above range. However, in order to obtain a sufficiently low viscosity, the weight average molecular weight of the polymer binder must be within the above range. Furthermore,
Surprisingly, it has been found that the ratio of these two properties (Mw/Mn) is less than or equal to 5.5, preferably less than or equal to 4.0. A polymer whose ratio of Mw to Mn is as small as possible, that is, the ratio Mw/
It is preferred to use polymers with Mn approximately 1.5, ideally close to 1.0. However, such polymers are not available with current commercial scale polymerization techniques. Suitable Mn values for polymeric binders are
It has been found that the Mn value is within a relatively narrow range of 50,000 to 100,000, and more preferably the Mn value is in the range of 60,000 to 80,000. Similarly, suitable Mw values for polymeric binders range from 150,000 to 350,000. Preferably, the Mw value is in the range of 200,000 to 300,000. In addition to the above physical properties, it is important for practical applications that the glass transition temperature (Tg) of the binder polymer, including any plasticizers, is at least -30°C and does not exceed +45°C. It is necessary for the following reasons. Tg of binder including plasticity is -20
℃~+20℃ is preferred. If the Tg exceeds 45°C, the solvent-free dispersion has very poor adhesion to other layers and is extremely brittle. Although polymers meeting all of these specific criteria are not known, they can nonetheless be produced by those skilled in the art of acrylate polymerization by conventional solution polymerization techniques. Typically, acidic acrylate polymers are
α- in an organic solvent with a relatively low boiling point (75-150℃)
The β-ethylenically unsaturated acid and one or more copolymerizable vinyl monomers are combined into a 20-60% monomer mixture solution, then a polymerization catalyst is added to cause polymerization, and the solution is refluxed at atmospheric pressure. Produced by heating the mixture to temperature. After completion of the polymerization reaction, the resulting acid polymer solution is cooled to room temperature,
A sample is taken and the viscosity, molecular weight, acid equivalent, etc. of the polymer are measured. In order to obtain a better binding effect, it is preferred to use at least 2% by weight of polymer binder to 98% by weight of ceramic solids. More preferred is at least 5% by weight of polymeric binder. The amount of binder depends in part on the surface area of the ceramic solid particles. Generally, large surface area ceramic solids require larger amounts of binder. C. Organic Medium The organic medium in which the ceramic solids are dispersed comprises a polymeric binder dissolved in a volatile organic solvent;
Optionally, it comprises other dissolved substances such as plasticizers, mold release agents, thixotropic agents, stripping agents, antifouling agents and wetting agents. By adjusting the rheological properties of the inventive dispersion and by varying the solvent content of the organic medium, the inventive compositions can be applied to substrates by methods other than molding, such as screen printing. When using the composition by screen printing,
Conventional organic media materials used for thick film materials may be used as long as the acrylic polymer is completely dissolved therein at the temperature of use. For molding solutions, the solvent content of the organic medium is high enough that a complete solution of the polymer is obtained and that the solvent can be volatilized from the dispersion by the application of relatively low levels of heat at atmospheric pressure. Selected to provide volatility. In addition, the solvent must boil readily below the boiling point and decomposition temperature of any other additives contained in the organic medium. Therefore, solvents with boiling points at atmospheric pressure of 150° C. or less are often used. Such solvents include benzene, acetone, xylene, methanol, ethanol, methyl ethyl ketone, 1,1,1-trichloroethane, tetrachloroethylene, amyl acetate,
2,2,4-triethylpentanediol-1,
Contains 3-monoisobutyrate, toluene, methylene chloride, 2-propanol and Freon™ TF (trichlorotrifluoroethane). However, it is often desirable to apply the compositions of the invention as a thick film paste by techniques such as screen printing. In this case, the composition needs to have a suitable viscosity so that it can easily pass through the screen. In addition, they must be thixotropic in order to set up quickly after screen printing, which gives good resolution. Although the rheological properties are most important, the organic medium is formed to provide adequate wetting of the solid and substrate, good drying speed, dry film strength that can resist rough handling, and good sinterability. Preferably. Good appearance of the fired composition is also important. On the other hand, if the dispersion is applied as a thick film paste, the usual thick film organic media can be used, subject to appropriate rheological adjustment and the use of less volatile solvents. The organic medium for most demanding film compositions is typically a solution of a resin in a solvent, often a solvent solution containing both a resin and a thixotropic agent. This solution typically boils in the range of 130-350°C. Particularly preferred resins for this purpose are polymethyl acrylates of lower alcohols and monobutyl ethers of ethylene glycol monoacetate. The most widely used solvents in the case of thick films are terpenes such as alpha- or beta-terpinol, or these and other solvents such as kerosene, dibutyl phthalate, butyl carbitol,
It is a mixture of butyl carbitol acetate, hexylene glycol, and high boiling alcohols and alcohol esters. Various combinations of these and other solvents are prepared to obtain the desired viscosity and required volatility. Commonly used thixotropic agents are hydrogenated castor oil and its derivatives. Of course, the shear thinning inherent in suspensions
It is not always necessary to incorporate a thixotropic agent as the solvent/resin properties together with thinning can meet this requirement by themselves. The ratio of organic medium to inorganic solids in the dispersion can vary considerably and depends on the manner in which the dispersion is applied and the type of organic medium used. Typically, to obtain good coverage, the dispersion contains 60-90% by weight solids and 40-10% by weight organic medium. Such dispersions are usually in a semi-liquid state and are commonly referred to as "pastes". This paste is conveniently manufactured in a three roll mill. The viscosity of the paste is typically within the following ranges when measured at room temperature using a Bruckfield viscometer at low, medium and high shear speeds:

TABLE The amount and type of organic vehicle used is determined by the final desired viscosity and print thickness. As mentioned above, the organic medium can contain a small amount of a plasticizer compared to the binder polymer that serves to lower the Tg of the binder polymer.
However, the use of such materials should be kept to a minimum in order to reduce the amount of organic material that must be removed when firing the formed film. The choice of plasticizer is, of course, primarily determined by the polymer to be modified. Plasticizers that have been used in various binder systems include diethyl phthalate, dibutyl phthalate, dioxyphthalate, butylbenzyl phthalate, alkyl phthalate, polyalkylene glycols, glycerol, poly(ethylene oxide), hydroxyethylated These include alkylphenols, dialkyldithiophosphonates, and poly(isobutylene). Of course, butylbenzyl phthalate is most often used in acrylic polymer systems because it is effective at relatively low concentrations. The amount of plasticizer used in the compositions of the invention depends on how effective a particular plasticizer is in reducing the Tg of the polymer in which it is used and relative to the Tg change required for that polymer. determined by the proportion of Thus, the amount of plasticizer can vary from 0 to 75% by weight of the base polymer. Test Methods In the following examples, the test methods described below were used to determine the properties of the polymeric binder of the compositions of the present invention and the properties of the green tape made from the compositions. A Molecular Weight Weight average and number average molecular weights are calculated for a solution of the test polymer dissolved in tetrahydrofuran.
A set of Model 6000A pump, Model 401R1 detector, and four μ-Styrogel columns (10 ⁵ , 10 ⁴ ,
5×10 ² and 10 ² ) using a water chromatography system. The measurement standard polymer is poly(methyl methacrylate),
It was Lucite40. (Lucite is in Delaware,
EIdu Pont de Nemours and Wilmington
Company, Inc.'s trademark related to acrylic resin. ) B Viscosity All slip viscosities are Bruckfield
Using LVT viscometer, No. 2 spindle,
Measurements were made at 6 RPM and a temperature of 25°C. C Glass Transition Temperature The glass transition temperature of the binder polymer, whether plasticized or not, is determined by the Du Pont Model 990
Measurements were made using a combination of thermal analyzer and Du Pont Model 951 thermogravimetric analyzer module. Preparation of molded slips In the following examples, the organic medium used to produce molded slips had the following composition:

[Table] The following ceramic dielectric materials were used in the examples: (1) CL750 is an NPO-type dielectric material;
Based on BaTiO ₃ and NbTiO ₃ and also contains bismuth. (2) BL162 is a BX/X7R-type bismuth-containing dielectric material based on _BaTiO3 . (3) H602 is a Z5U-type bismuth-free dielectric material based on _BaTiO3 . The three dielectric materials listed above were purchased from EI du Pont de Nemours and Wilmington, Delaware.
Company Inc.'s Day Vision Solid State
It is a product of Dielectrics. In the production of molded slips, the organic medium, ceramic powder and mixed flint stone are placed in a ceramic jar and ground for 14 hours. The milled dispersion is transferred from the mill jar to a glass jar, which is placed in a constant temperature bath or oven for a sufficient time to bring the slip temperature to 25°C. Slip viscosity is measured at 25°C. In the examples below, all compositional proportions are in weight percent (%wt) unless otherwise specified. EXAMPLES Examples 1-3 Three molding slips were made from acidic acrylic terpolymers with varying amounts of acidic comonomer from 0.4 to 1.8%. Molding slips were prepared for each terpolymer using the methods and proportions described above, and the viscosity of the slips was measured.

[Table] From the above data it can be seen that slips made from highly acidic polymers are unstable and have very high viscosities, properties that tend to cause the dielectric material to agglomerate. On the contrary, the two low acid polymers showed quite stable low viscosities. Preferably, the polymeric binder component of the present invention contains no more than 1.5% by weight of side chain functional group-containing comonomer. Examples 3 to 6 Three polymers having the same composition as claimed in claim 1 were each molded on a glass plate as a 30% by weight solution in methyl ethyl ketone to a wet thickness of 6.
A mill film was formed. Then at room temperature 48~
After drying for 72 hours, the dry film had a thickness of 1~
It was 1.5 mil. 1/2 x 2 1/2 inches (1.27 x 6.35
A tensile sample of 2 in/sec (5.1 cm) was cut out using an Instron testing machine.
cm/sec). These data are shown in Table 3:

【table】

[Table] From the above data, the polymer of the present invention (Example 4
and 5) are found to have significantly higher flexibility, elongation at break and toughness (fracture energy) despite the fact that they have a significantly lower weight average molecular weight than the polymer of Example 6. The solution viscosity of the polymers used in this invention is also fairly low. Examples 7-8 Polymers similar to Examples 4 and 6 were used to make two molding slips as described above. The composition of both slips was the same with respect to the amount of solids, plasticizer and solvent. Green tape was later produced from both slips. Tensile samples of the same dimensions as Examples 4-6 were prepared, made into 15 layer laminates without electrodes, and tested for tensile properties in the same manner as Examples 4-6. The data are shown in Table 4 below:

【table】

[Table] From the above data, it can be seen that the green tape made from the molding slip of the present invention has high flexibility as expressed by elongation at break, and high toughness as indicated by breaking energy. Examples 9 to 11 Further, 3 each having a viscosity of 600 to 650 cps
Ceramic slips for molding seeds were manufactured. The molding slips were made from three different acrylic polymers using the same dielectric solid. Form green tape from each of the three types of slips and store at room temperature.
Dry for 36-48 hours. The data in Table 5 below is
This shows that the composition of the present invention (Example 9) contained significantly more dielectric material at a comparable viscosity compared to the compositions using conventional polymeric binders (Examples 10 and 11). In addition, Example 11 shows that the higher Tg requires more plasticizer to obtain a good lamination bond. It will be seen from Example 11 that suitably dispersible molding slips can also be obtained from acrylic polymers without acid groups.
However, to have such dispersibility they must have very high molecular weight and are therefore not preferred for use in the compositions of the present invention.

Table: Examples 12-20 Nine molding slip compositions were prepared to determine how much of the composition of the present invention contained a commercially available polymer whose molecular weight did not comply with the relationship of the present invention. Explain how many ceramic solids can be mixed.

[Table] From the above data, with a ceramic amount of 200 parts by weight,
It is interesting to note that molding slips using polymers outside the scope of the invention have a viscosity of 1750 cps, whereas the composition of the invention has a viscosity of only 590 cps. Similarly, at an amount of 240 parts by weight, the viscosity of the slip with conventional polymers is 4800 cps, compared to 1000 cps with the composition of the invention.
Based on the same viscosity (1000 cps), approximately 44% more solids can be incorporated into molding slips with binder polymers within the scope of the present invention. Furthermore, the amount of organic material removed by pyrolysis is
Reduced by 29%. Examples 21-26 Several additional molding slips were made to study the effect of viscosity reducing agent concentration on slip viscosity. In addition, there are further two, only one of which is based on a binder polymer within the scope of the invention.
For seed compositions, the effect of viscosity-lowering agents at fixed concentrations on slip viscosity was observed.

[Table] From this data, the viscosity reducing agent is effective in reducing slip viscosity at low concentrations;
(0.5% by weight of dielectric solids) causes destabilization of the dispersion, leading to high viscosity, unstable viscosity, and agglomeration of the solids. However, it is very interesting that the use of a viscosity reducing agent had even less effect in the molding slip (Example 26) which utilized a binder polymer without acid functional groups. Examples 27-31 The importance of molecular weight and the ratio of weight-average molecular weight to number-average molecular weight is demonstrated by the following experiments in which transparent films were prepared using five polymers in the manner described in Examples 3-6. Illustrated by example.
The polymer film of Example 27, which is within the scope of the present invention, did not break even after being folded five times through 180 degrees and was completely rigid. Example 28, which is outside the scope of the invention, showed good fastness but had excessive solution viscosity. On the other hand, embodiments that are also outside the scope of the invention
29-31 were very fragile. That is, when folded,
they were damaged. This fragility of the cast film affects the ease with which multilayer capacitors made from the corresponding slips can be cut.

【table】

[Table] Examples 32 to 35 Four types of molding slips were prepared in the same manner as above. One had a polypale resin viscosity reducer added, the other two had a small amount of glacial acetic acid, and the remaining one had a standard composition with no additives. After testing the viscosity of four types of slips, it was found that glacial acetic acid was also effective in reducing slip viscosity.

[Table] Examples 36 to 46 Furthermore, several compositions having different polymer compositions were prepared and dispersion tests were conducted to examine the compatibility of each polymer with the molding slip. In this dispersion test, 4.5 g of ceramic powder (BL162), 45.0 g of xylene or 1,1,1-
Trichloroethane and 50 g of polymer solution (30% polymer in MEK) were placed in an appropriately sized bottle, shaken in a mechanical paint shaker for 30 minutes, and then allowed to stand for 8 hours. After 8 hours, turbidity or clarity was observed. A cloudy sample indicated that it was well dispersed, whereas a clear sample indicated that it was unstable and therefore lacked the desired dispersion properties.

Table: Examples 38, 39, 44 and 45 show that good dispersion cannot be obtained without side chain functionality. Examples 41-43 show that in addition to acid groups, amine groups can be used to obtain good dispersion. Examples 47-54 Several slip compositions with similar polymer compositions were prepared. Each slip was subjected to the turbidity tests of Examples 36 to 46, and the viscosity was measured before and after storage at 40° C. for 2 weeks using a Haake Rotovisco RV3 viscometer to examine changes in viscosity.

【table】

TABLE Example 52 shows that excessive side chain functionality is detrimental to dispersion stability as seen by the Haake viscosity stability test. Example 54
show that the lack of side chain functionality is detrimental to dispersion stability, although the viscosity of the slip remains stable upon heat aging.
Molding slips made from polymers meeting the compositional requirements of the present invention (Examples 47-51) exhibited good dispersibility and good viscosity stability. Example 56 Closed type flash point (ASTM test method D56) is 200℃
Another slip composition was prepared using a solvent containing a sufficient amount of trichlorotrifluoroethane to obtain the above slip composition. A 4 mil thick tape was cast from this slip using the method described above. The resulting tape was strong and free of pinholes. Additionally, the tape had a uniform thickness and was easy to laminate when used to make multilayer capacitors. This slip had the composition shown below. Nonflammable slip composition glass powder 32.2%wt. Al ₂ O ₃ 16.5 SiO ₂ 4.0 Polymer ⁽¹⁾ 3.5 Dioctyl phthalate 1.3 1,1,1-trichloroethane 33.2 Methylene chloride 2.0 2-propanol 1.7 Trichlorotrifluoroethane 3.0 Methyl ethyl ketone 2.3 (1)62.3/37.1/0.6 ethyl methacrylate/
Methyl Acrylate/Methacrylic Acid Examples 56-60 To observe the effect of a plasticizer on the glass transition temperature (Tg) of a polymer,
Make a solution of seeds and adjust the amount of plasticizer to that of the polymer.
Changed up to 100% by weight. The above solution was made by adding a plasticizer to a solution of the polymer and then removing the solvent. The data shown in Table 12 below shows that using equal amounts of plasticizer and polymer makes quite a substantial difference.

【table】

Claims (1)

[Scope of Claims] 1 (a) finely divided ceramic solid particles, (b) an alkyl methacrylate having 1 to 8 carbon atoms, an alkyl acrylate having 1 to 8 carbon atoms, and an ethylenically unsaturated carboxylic acid. or amines, wherein the ethylenically unsaturated carboxylic acid or amine does not exceed 5% by weight of the polymer; A ceramic composition comprising a dispersion in a solution dissolved in a solvent, wherein the polymer has a number average molecular weight (Mn) of 50,000 to 100,000, a weight average molecular weight (Mw) of 150,000 to 350,000, and the ratio of Mw to Mn is is 5.5
or less, and the total amount of unsaturated carboxylic acids or amines in the polymer or mixture thereof is from 0.2 to 2.0.
% by weight, and the glass transition temperature of the polymer and the plasticizer that may be present therein is between -30°C and +45°C. 2. The composition according to claim 1, wherein the alkyl methacrylate is ethyl methacrylate and the alkyl acrylate is methyl acrylate. 3. The composition of claim 1, wherein the ethylenically unsaturated carboxylic acid is a monocarboxylic acid selected from acrylic acid, methacrylic acid, and mixtures thereof. 4. The composition of claim 3, wherein the carboxylic acid is methacrylic acid. 5. Claim 1, wherein the ethylenically unsaturated carboxylic acid is a dicarboxylic acid selected from itaconic acid, fumaric acid, maleic acid, maleic anhydride, half esters thereof, and mixtures thereof.
composition of the term. 6. The composition of claim 1, wherein the multipolymer comprises 40-80% by weight alkyl methacrylate and 60-20% by weight alkyl acrylate. 7. The composition of claim 1, wherein the weight ratio of alkyl methacrylate to alkyl acrylate is from 1.5 to 2.5:1. 8 Mn is 60000~80000, Mw is 200000~
300,000. 9. The composition of claim 1, wherein the ceramic solid is a dielectric solid or a precursor thereof. 10. The composition of claim 9, wherein the dielectric solid is selected from titanates, zirconates, stannates, precursors thereof, and mixtures thereof. 11 The dielectric solid is BaTiO ₃ , CaTiO ₃ ,
10. The composition of claim 9, wherein the titanate is selected from _SrTiO3 , _PbTiO3 , _NbTiO3 , rare earth titanates, precursors thereof and mixtures thereof. 12. The composition of claim 10, wherein the dielectric solid is selected from Ba or Ca stannates, precursors thereof, and mixtures thereof. 13. The composition of claim 10, wherein the dielectric solid is selected from Ba or Ca zirconates, precursors thereof, and mixtures thereof.