JP2006117843A - Paste for use in coating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paste for use in coating which is excellent in the dispersing property for inorganic powders such as an electroconductive powder, ceramic powder and glass powder and which can develop an extremely excellent coating property and printing ability. <P>SOLUTION: The paste for use in coating contains a binder of a polyvinyl-based resin, an organic solvent and an inorganic powder, wherein the above polyvinyl-based resin has a content of a resin with a molecular weight of 100,000-5,000,000 of 30 wt.% or more. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a coating paste that is excellent in dispersibility of inorganic powders such as conductive powders, ceramic powders, and glass powders and that can exhibit extremely high coating properties and printability.

In recent years, after applying paste in which inorganic powder such as conductive powder, ceramic powder and glass powder is dispersed in binder resin in various fields, it is fired to prepare precise conductive film, ceramic film, glass film, etc. For example, a multilayer electronic component such as a multilayer ceramic capacitor using such a paste generally has the following steps as disclosed in Patent Document 1 or Patent Document 2. It is manufactured through.

First, a ceramic slurry composition is prepared by adding a binder resin such as polyvinyl butyral resin or poly (meth) acrylate ester resin, ceramic raw material powder, plasticizer, dispersant, etc. to an organic solvent and mixing them uniformly. Then, it is cast on a support surface such as a polyethylene terephthalate film or a SUS plate that has been subjected to a release treatment, and the support is peeled off to obtain a ceramic green sheet. Next, a degreasing treatment is carried out on a laminate produced by alternately stacking a plurality of conductive pastes obtained by dispersing conductive powder such as palladium or nickel by screen printing on the obtained ceramic green sheet, and thermocompression bonding. Then, a multilayer ceramic capacitor is manufactured through a step of sintering an external electrode on the end face of the fired ceramic fired product.

Further, a paste in which an inorganic powder is dispersed in a binder resin is also used for manufacturing a plasma display panel. For example, as disclosed in Patent Document 3 and Patent Document 4, the following steps are generally performed. It is manufactured after.
First, a front glass substrate is produced by forming a display electrode and a bus electrode on a glass substrate, and further forming a dielectric layer and an MgO layer. Subsequently, after forming a data electrode and a dielectric layer on another glass substrate, a back glass substrate is produced by further forming a barrier rib and a phosphor layer. And a plasma display panel is manufactured through the process of bonding a front glass substrate and a back glass substrate, enclosing exhaust gas and discharge gas, and mounting a printed circuit board.
Here, the barrier ribs formed on the back glass substrate are formed by applying a glass paste in which glass powder is dispersed in a binder resin and a solvent, and then exposing and developing to form a pattern, which is then cut by sandblasting and fired. It is manufactured by.

Thus, as a binder resin for supporting inorganic powder such as conductive powder, ceramic powder, glass powder and the like used in manufacturing a multilayer ceramic capacitor and a plasma display panel, ethyl cellulose resin has been mainly used conventionally. A paste using ethyl cellulose as a binder resin is excellent in coating properties, and in particular, a coating method such as screen printing can be adopted, so that a coating film having a precise shape can be easily formed. However, when ethyl cellulose is used as a conductive paste for manufacturing a multilayer ceramic capacitor or as a binder resin for a ceramic paste, it is called so-called delamination because of poor adhesion to a ceramic green sheet made of polyvinyl acetal resin. Delamination was likely to occur. In addition, since ethyl cellulose is inferior in thermal decomposability, there has been a problem that even if the degreasing treatment is performed, the carbon component remains after firing and the electrical characteristics are impaired.

On the other hand, when ethyl cellulose is used as the binder resin of the glass paste for producing the barrier rib of the plasma display panel, ethyl cellulose is inferior in alkali resistance and has low adhesion to glass, so that peeling occurs in the development process, and the barrier rib There is a problem that the desired pattern is not formed.

On the other hand, using polyvinyl-type resin, such as polyvinyl acetal resin, as binder resin of the paste for coating is examined. Polyvinyl acetal resin has excellent adhesive strength with ceramic green sheets and has alkali resistance. Therefore, it is a conductive paste or ceramic paste for manufacturing multilayer ceramic capacitors, and a glass paste for manufacturing barrier ribs for plasma display panels. When used as a binder resin, the occurrence of delamination can be suppressed.

However, when a polyvinyl acetal resin is used as a binder resin, the coating property is lowered, and particularly when the coating is attempted by a screen printing method, a problem such as stringing or clogging occurs, resulting in poor release of the plate. However, there is a problem that the thickness accuracy is lowered and the production yield is lowered because the pattern cannot be drawn clearly.
Conventionally, when these pastes are used, the coatability has been improved by adjusting the amount of resin to be added, but if the amount of resin to be added is reduced, the viscosity is insufficient and the pattern cannot be drawn clearly. Further, the dispersibility of the inorganic particles is insufficient, and conversely, if the amount of the resin is increased, there is a problem that the carbon component remains during firing.

Furthermore, when manufacturing a multilayer ceramic capacitor, when stacking ceramic green sheets coated with a conductive paste, a step is created between the portion where the conductive paste is applied and the portion where the conductive paste is not applied, and the laminate is pressed. In this case, the ceramic green sheet and the conductive layer are peeled off to cause delamination, and the dielectric layer and the conductive layer are deformed at the end of the multilayer ceramic capacitor. In particular, in recent years, there has been a demand for higher capacity in multilayer ceramic capacitors, and further multilayering and thinning have been studied. Therefore, it is conceivable that there will be a further level difference due to the presence or absence of coating of the conductive paste.

On the other hand, Patent Document 5 discloses a step difference by screen-printing a conductive paste on a ceramic green sheet and then applying the ceramic paste to a portion where the conductive paste is not applied by a method such as screen printing. A method for preventing the occurrence of the problem is described. However, such a method has a problem in terms of cost because it is necessary to separately perform a process of printing the ceramic paste on the non-coated portion of the conductive paste.
Japanese Patent Publication No. 3-35762 Japanese Patent Publication No. 4-49766 JP-A-8-222135 JP 2002-63849 A JP 2002-280250 A

In view of the above situation, the present invention is excellent in dispersibility of inorganic powders such as conductive powders, ceramic powders, and glass powders, can ensure high viscosity even with a small amount of binder resin, and has extremely excellent coating properties. An object of the present invention is to provide a coating paste capable of exhibiting printability.

The present invention is a coating paste containing a binder resin composed of a polyvinyl resin, an organic solvent, and an inorganic powder, wherein the polyvinyl resin has a molecular weight of 100,000 to 5,000,000 in a proportion of 30% by weight or more. It is a certain coating paste.
The present invention is described in detail below.

As a result of intensive studies, the present inventors have found that even when a polyvinyl resin is used as the binder resin, the use of the polyvinyl resin having a specific molecular weight distribution results in a small resin amount. Furthermore, the viscosity of the coating paste is improved and a paste excellent in coating property can be obtained, and the adhesiveness and alkali resistance with the ceramic green sheet are excellent, and the printing property when screen printing is performed is excellent. The inventors have found that a coating paste can be obtained, and have completed the present invention.

The coating paste of the present invention contains a binder resin made of a polyvinyl resin.
The lower limit of the ratio of the binder resin having a molecular weight of 100,000 to 5,000,000 is 30% by weight. By containing a large amount of the resin having a molecular weight within the above range, the viscosity of the coating paste can be improved even if the amount is small, and the carbon residual ratio during firing can be reduced. Further, since the paste viscosity is increased, the shearing force during kneading is increased, and the dispersibility of the inorganic powder can be improved. Furthermore, it is possible to obtain a paste having excellent viscosity characteristics such as thixotropy and excellent coating properties, particularly screen printing properties.
In the binder resin, when the proportion of those having a molecular weight of less than 100,000 is increased, the viscosity is lowered, and when the proportion of those having a molecular weight exceeding 5 million is increased, the solubility in a solvent is deteriorated. A preferred lower limit of the proportion of those having a molecular weight of 100,000 to 5,000,000 is 35% by weight, and a more preferred lower limit is 40% by weight.

The polyvinyl resin is not particularly limited as long as it can be used as a binder resin, and examples thereof include acrylic resins, polyvinyl acetal resins, and modified polyvinyl acetals. Of these, polyvinyl acetal resins and / or modified polyvinyl acetal resins are preferred.

The modified polyvinyl acetal resin is not particularly limited. For example, acrylic acid, methacrylic acid, (anhydrous) phthalic acid, (anhydrous) maleic acid, (anhydrous) itaconic acid, acrylonitrile methacrylonitrile, acrylamide, methacrylamide, trimethyl- (3-acrylamido-3-dimethylpropyl) -ammonium chloride, acrylamido-2-methylpropanesulfonic acid and its sodium salt, ethyl vinyl ether, butyl vinyl ether, N-vinyl pyrrolidone, vinyl chloride, vinyl bromide, vinyl fluoride And those containing components derived from ethylenically unsaturated monomers such as vinylidene chloride, vinylidene fluoride, tetrafluoroethylene, sodium vinyl sulfonate and sodium allyl sulfonate. By containing a component derived from these ethylenically unsaturated monomers, it is possible to impart the viscosity stability over time of the paste and the like.

The modified polyvinyl acetal resin is preferably a modified polyvinyl acetal resin composed of structural units represented by the following general formulas (1), (2), (3) and (4). The modified polyvinyl acetal resin includes a vinyl ester unit represented by general formula (1), a vinyl alcohol unit represented by general formula (2), an α-olefin unit represented by general formula (3), and a general formula ( It consists of acetal units represented by 4). In addition, the ratio of each structural unit, selection of R ¹ , R ² , or selection of n can adjust various properties such as viscosity and thixotropy to exhibit excellent coating properties, especially screen printing. A paste excellent in properties can be obtained.

式中、Ｒ^１は、炭素数１〜２０の直鎖又は枝分かれ状のアルキル基を表し、Ｒ^２は、水素、炭素数１〜２０の直鎖、枝分かれ状若しくは環状のアルキル基又はアリール基を表す。また、ｎは１〜８の整数を表す。更に、変性ポリビニルアセタール樹脂中、一般式（３）で表される構造単位の含有量は１〜２０モル％、一般式（４）で表される構造単位の含有量は３０〜７８モル％である。

In the formula, R ¹ represents a linear or branched alkyl group having 1 to 20 carbon atoms, and R ² represents hydrogen, a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, or an aryl group. To express. N represents an integer of 1 to 8. Further, in the modified polyvinyl acetal resin, the content of the structural unit represented by the general formula (3) is 1 to 20 mol%, and the content of the structural unit represented by the general formula (4) is 30 to 78 mol%. is there.

In the modified polyvinyl acetal resin, the content of the vinyl ester unit represented by the general formula (1) is not particularly limited.
In the modified polyvinyl acetal resin, the preferable lower limit of the content of the vinyl alcohol unit represented by the general formula (2) is 20 mol%, and the preferable upper limit is 30 mol%. If it is less than 20 mol%, the solvent solubility of the modified polyvinyl acetal resin is inferior and may not be used as a binder resin for coating paste. If it exceeds 30 mol%, it is conductive powder, ceramic powder, glass powder. Such as dispersibility may be inferior. A more preferred upper limit is 27 mol%.

When two or more vinyl alcohol units represented by the general formula (2) are continuous, the preferable lower limit of the ratio in which adjacent hydroxyl groups are in the trans position is 60%. When it is 60% or more, the interaction between the hydroxyl groups in the molecule is larger than the interaction between the hydroxyl groups in the molecule, and the affinity with the conductive powder, ceramic powder, glass powder, etc. is improved. , These dispersibility are improved. A more preferred lower limit is 70%.

In the modified polyvinyl acetal resin, the preferable lower limit of the content of the α-olefin unit represented by the general formula (3) is 1 mol%, and the preferable upper limit is 20 mol%. When it is less than 1 mol%, the thermal decomposability of the resulting coating paste may be inferior, and when it exceeds 20 mol%, the solvent solubility of the modified polyvinyl acetal resin is inferior and used as a binder resin for the coating paste. Or the viscosity stability over time of the binder resin of the coating paste may deteriorate. A more preferred lower limit is 2 mol%, and a more preferred upper limit is 10 mol%. A more preferred upper limit is 8 mol%.

The α-olefin unit is not particularly limited. For example, a unit derived from ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 4-methyl-1-pentene and the like. Is mentioned. Of these, ethylene units derived from ethylene are preferred.

In the modified polyvinyl acetal resin, when the α-olefin units represented by the general formula (3) are continuous, the preferable upper limit of the number of the continuous α-olefin units is 10. If it exceeds 10, the solvent solubility of the modified polyvinyl acetal resin is inferior, and it may not be used as a binder resin for a coating paste.

In the acetal unit represented by the general formula (4), R ² is preferably CH ₃ and / or C ₃ H ₇ . This is because CH ₃ and / or C ₃ H ₇ can stably produce a modified polyvinyl acetal resin having a target composition and has good solubility in a solvent.

The minimum with preferable content of the acetal unit represented by the said General formula (4) is 30 mol%, and a preferable upper limit is 78 mol%. When it is less than 30 mol%, the resulting modified polyvinyl acetal resin becomes insoluble in an organic solvent, which hinders paste production. When it exceeds 78 mol%, the toughness of the modified polyvinyl acetal resin obtained by reducing the residual hydroxyl group may be impaired, and the coating strength at the time of paste printing may be lowered. A more preferred lower limit is 55 mol%.

In the modified polyvinyl acetal resin, when two or more acetal units represented by the general formula (4) are continuous, the preferable lower limit of the ratio of adjacent acetal groups in the trans position is 30%, and the preferable upper limit is 70%. is there. If it is less than 30%, the solvent solubility of the modified polyvinyl acetal resin is poor and may not be used as a binder resin for coating paste. If it exceeds 70%, the acetal bond tends to dissociate and the viscosity changes. The storage stability may be inferior, such as increasing the size.

The modified polyvinyl acetal resin further includes acrylic acid, methacrylic acid, (anhydrous) phthalic acid, (anhydrous) maleic acid, (anhydrous) itaconic acid, acrylonitrile methacrylonitrile, acrylamide, methacrylamide, trimethyl- (3-acrylamide- 3-dimethylpropyl) -ammonium chloride, acrylamido-2-methylpropanesulfonic acid and its sodium salt, ethyl vinyl ether, butyl vinyl ether, N-vinyl pyrrolidone, vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, fluoride You may contain the component derived from ethylenically unsaturated monomers, such as vinylidene, tetrafluoroethylene, sodium vinyl sulfonate, and sodium allyl sulfonate. By containing a component derived from these ethylenically unsaturated monomers, it is possible to impart viscosity stability over time to the modified polyvinyl acetal resin. However, even if it contains a component derived from these ethylenically unsaturated monomers, the content is preferably less than 2.0 mol%.

The degree of polymerization of the modified polyvinyl acetal resin is not particularly limited, but a preferred lower limit is 300 and a preferred upper limit is 2400. If it is less than 300, the strength of the coating film obtained by screen printing is inferior, and cracks and the like are likely to enter. If it exceeds 2400, the viscosity of the coating paste becomes too high, and handling properties are increased. May decrease.

The modified polyvinyl acetal resin can be produced by acetalizing a modified polyvinyl alcohol having an α-olefin unit content of 1 to 20 mol% and a saponification degree of 80 mol% or more.

The modified polyvinyl alcohol can be obtained by saponifying a copolymer obtained by copolymerizing a vinyl ester and an α-olefin. Examples of the vinyl ester used in this case include vinyl formate, vinyl acetate, vinyl propionate, vinyl pivalate and the like. Among these, vinyl acetate is preferable from an economical viewpoint. Moreover, when obtaining the modified polyvinyl acetal containing the component derived from the said ethylenically unsaturated monomer, an ethylenically unsaturated monomer is further copolymerized. In addition, a terminal-modified polyvinyl alcohol obtained by copolymerizing a vinyl ester monomer such as vinyl acetate and an α-olefin in the presence of a thiol compound such as thiol acetic acid or mercaptopropionic acid, and saponifying it. Can be used.

The lower limit of the saponification degree of the modified polyvinyl alcohol is 80 mol%. If it is less than 80 mol%, the solubility of the modified polyvinyl alcohol in water becomes poor, making the acetalization reaction difficult, and if the amount of hydroxyl groups is small, the acetalization reaction itself becomes difficult.

When the modified polyvinyl alcohol is used, it is necessary to use a modified polyvinyl alcohol having an α-olefin content in the range of 1 to 20 mol%, but the α-olefin content is in the range of 1 to 20 mol%. For example, the modified polyvinyl alcohol may be used alone. If the α-olefin content of the finally obtained modified polyvinyl acetal resin is 1 to 20 mol%, the modified polyvinyl alcohol and the unmodified polyvinyl alcohol are used. May be used in combination. In addition, regarding the saponification degree, if the saponification degree of the modified polyvinyl alcohol at the time of acetalization is 80 mol% or more, the modified polyvinyl alcohol alone or the modified polyvinyl alcohol having a saponification degree of 80 mol% or more is used. And modified polyvinyl alcohol having a saponification degree of less than 80 mol% may be mixed to adjust the saponification degree to 80 mol% or more as a whole.

The modified polyvinyl acetal resin can be produced by acetalizing the modified polyvinyl alcohol. The method for acetalization is not particularly limited, and a conventionally known method can be used. Examples thereof include a method of adding various aldehydes to the aqueous solution of the modified polyvinyl alcohol in the presence of an acid catalyst such as hydrochloric acid.

The aldehyde used for the acetalization is not particularly limited. For example, formaldehyde (including paraformaldehyde), acetaldehyde (including paraacetaldehyde), propionaldehyde, butyraldehyde, amylaldehyde, hexylaldehyde, heptylaldehyde, 2-ethylhexylaldehyde, Examples include cyclohexyl aldehyde, furfural, glyoxal, glutaraldehyde, benzaldehyde, 2-methylbenzaldehyde, 3-methylbenzaldehyde, 4-methylbenzaldehyde, p-hydroxybenzaldehyde, m-hydroxybenzaldehyde, phenylacetaldehyde, β-phenylpropionaldehyde and the like. Of these, acetaldehyde or butyraldehyde is preferable in terms of productivity and property balance. These aldehydes may be used alone or in combination of two or more.

The acetalization degree of the acetalization is preferably in the range of 30 to 78 mol% in terms of the total acetalization degree regardless of whether a single aldehyde or a mixed aldehyde is used. If the total degree of acetalization is less than 30 mol%, the resin becomes water-soluble and insoluble in an organic solvent, which hinders paste production. When the total degree of acetalization exceeds 78 mol%, the residual hydroxyl group is decreased, the toughness of the modified polyvinyl acetal resin is impaired, and the coating strength during paste printing may be reduced.
In this specification, as a method for calculating the degree of acetalization, since the acetal group of the modified polyvinyl acetal resin is acetalized from two hydroxyl groups, the two acetalized hydroxyl groups are counted. The method is employed to calculate the mole percent of the degree of acetalization.

The minimum with preferable content of the binder resin used for the coating paste of this invention is 30 weight%. If it is less than 30% by weight, the effects of the present invention may not be fully exhibited.

The coating paste of the present invention contains an inorganic powder.
Examples of the inorganic powder include conductive powder, ceramic powder, and glass powder.

When a conductive powder is used as the inorganic powder, the coating paste of the present invention can be used as a conductive paste.
The conductive powder is not particularly limited as long as it exhibits sufficient conductivity, and examples thereof include fine particles made of nickel, palladium, platinum, gold, silver, copper, and alloys thereof. These metal materials may be used independently and may use 2 or more types together.

When the conductive powder is used as the inorganic powder, the content of the binder resin is not particularly limited, but a preferable lower limit is 3 parts by weight and a preferable upper limit is 25 parts by weight with respect to 100 parts by weight of the conductive powder. If it is less than 3 parts by weight, the film formation performance of the conductive paste may be inferior, and if it exceeds 25 parts by weight, the carbon component tends to remain after degreasing and firing. A more preferred lower limit is 5 parts by weight, and a more preferred upper limit is 15 parts by weight.

When ceramic powder is used as the inorganic powder, the coating paste of the present invention can be used as a ceramic paste.
The ceramic powder is not particularly limited. For example, a powder made of alumina, zirconia, aluminum silicate, titanium oxide, zinc oxide, barium titanate, magnesia, sialon, spinemullite, silicon carbide, silicon nitride, aluminum nitride, or the like. Is mentioned. Especially, it is preferable to consist of the same component as the ceramic powder contained in the ceramic green sheet to be used. These ceramic powders may be used alone or in combination of two or more.

When the ceramic powder is used as the inorganic powder, the content of the binder resin is not particularly limited, but a preferable lower limit is 1 part by weight and a preferable upper limit is 50 parts by weight with respect to 100 parts by weight of the ceramic powder. If it is less than 1 part by weight, the film forming performance of the ceramic paste may be inferior. If it exceeds 50 parts by weight, the carbon component tends to remain after degreasing and firing. A more preferred lower limit is 3 parts by weight, and a more preferred upper limit is 30 parts by weight.

When glass powder is used as the inorganic powder, the coating paste of the present invention can be used as a glass paste.
The glass powder is not particularly limited. For example, lead oxide-boron oxide-silicon oxide-calcium oxide glass, zinc oxide-boron oxide-silicon oxide glass, lead oxide-zinc oxide-boron oxide-silicon oxide glass. Etc. These glass powders may be used independently and 2 or more types may be used together. Moreover, you may use aluminum oxide etc. together in the range which does not impair the objective of this invention.

The minimum with the preferable average particle diameter of the said glass powder is 0.05 micrometer, and a preferable upper limit is 10 micrometers. If it is less than 0.05 μm, when used as a glass paste for a barrier rib of a plasma display panel, the barrier rib may collapse during firing, and if it exceeds 10 μm, it is difficult to produce a dense barrier rib. Become.

The content of the binder resin when glass powder is used as the inorganic powder is not particularly limited, but a preferred lower limit is 2 parts by weight and a preferred upper limit is 40 parts by weight with respect to 100 parts by weight of the glass powder. If it is less than 2 parts by weight, the glass powder may not be reliably bound. If it exceeds 40 parts by weight, the carbon component tends to remain after degreasing and firing. A more preferred lower limit is 4 parts by weight, and a more preferred upper limit is 25 parts by weight.

The coating paste of the present invention contains a binder resin composed of a polyvinyl resin, and since the polyvinyl resin has a large proportion of a specific molecular weight, it is a conductive paste or ceramic paste for producing a multilayer ceramic capacitor. When the binder is used, the affinity with the ceramic green sheet is high and the occurrence of delamination can be suppressed. Moreover, since it is excellent in alkali resistance, when it is used as a binder of a glass paste for producing barrier ribs of a plasma display panel, a desired pattern can be formed without causing peeling even in the development process. Further, the obtained paste can exhibit extremely excellent coating properties, particularly screen printing properties.

The coating paste of the present invention contains an organic solvent.
The organic solvent is not particularly limited. For example, ketones such as acetone, methyl ethyl ketone, dipropyl ketone, and diisobutyl ketone; alcohols such as methanol, ethanol, isopropanol, and butanol; aromatic hydrocarbons such as toluene and xylene; Methyl propionate, ethyl propionate, butyl propionate, methyl butanoate, ethyl butanoate, butyl butanoate, methyl pentanoate, ethyl pentanoate, butyl pentanoate, methyl hexanoate, ethyl hexanoate, butyl hexanoate, acetic acid 2 -Esters such as ethyl hexyl and 2-ethylhexyl butyrate; methyl cellosolve, ethyl cellosolve, butyl cellosolve, α-terpineol, butyl cellosolve acetate, butyl carbitol acetate and the like. These organic solvents may be used independently and 2 or more types may be used together.

The coating paste of the present invention may further contain a dispersant.
Although it does not specifically limit as said dispersing agent, For example, a fatty acid, an aliphatic amine, an alkanolamide, and phosphate ester are suitable.
The fatty acid is not particularly limited. For example, saturated fatty acids such as behenic acid, stearic acid, palmitic acid, myristic acid, lauric acid, capric acid, caprylic acid, coconut fatty acid; oleic acid, linoleic acid, linolenic acid, sorbic acid And unsaturated fatty acids such as beef tallow fatty acid and castor-cured fatty acid. Of these, lauric acid, stearic acid, oleic acid and the like are preferable.
The aliphatic amine is not particularly limited. For example, laurylamine, myristylamine, cetylamine, stearylamine, oleylamine, alkyl (coconut) amine, alkyl (cured beef tallow) amine, alkyl (beef tallow) amine, alkyl (soybean) amine Etc.
The alkanolamide is not particularly limited, and examples thereof include coconut fatty acid diethanolamide, beef tallow fatty acid diethanolamide, lauric acid diethanolamide, and oleic acid diethanolamide.
It does not specifically limit as said phosphate ester, For example, polyoxyethylene alkyl ether phosphate ester and polyoxyethylene alkyl allyl ether phosphate ester are mentioned.

The coating paste of the present invention may contain conventionally known additives such as a plasticizer, a lubricant, and an antistatic agent as long as the effects of the present invention are not impaired.

The method for producing the coating paste of the present invention is not particularly limited. For example, the modified polyvinyl acetal resin, organic solvent, and inorganic powder such as conductive powder, ceramic powder, and glass powder are blended with a blender mill, three rolls. The method of mixing using various mixers, such as these, is mentioned.

By applying the coating paste of the present invention by a method such as screen printing, a very precise coating film containing inorganic powder can be formed.

The present invention is excellent in dispersibility of inorganic powders such as conductive powders, ceramic powders, and glass powders, can ensure high viscosity even with a small amount of binder resin, and exhibits extremely excellent coatability and printability. The present invention relates to a coating paste that can be applied.

In order to describe the present invention in more detail, examples will be given below, but the present invention is not limited to these examples.

Example 1
193 g of modified polyvinyl alcohol having an ethylene content of 5 mol% and a saponification degree of 99 mol% was added to 2900 g of pure water, and stirred at a temperature of 90 ° C. for about 2 hours for dissolution. This solution was cooled to 28 ° C., 20 g of hydrochloric acid having a concentration of 35% by weight and 115 g of n-butyraldehyde were added thereto, the liquid temperature was lowered to 20 ° C., and this temperature was maintained to carry out an acetalization reaction. The product precipitated out. Thereafter, the liquid temperature was kept at 30 ° C. for 5 hours to complete the reaction, followed by neutralization, washing with water and drying, to obtain a white powder of a modified polyvinyl acetal resin.

The obtained modified polyvinyl acetal resin was dissolved in DMSO-d ⁶ (dimethyl sulfoxide), and the degree of butyralization and the amount of hydroxyl groups were measured using ¹³ C-NMR (nuclear magnetic resonance spectrum). Was 71 mol%, and the amount of hydroxyl group was 23 mol%. Moreover, the molecular weight and molecular weight distribution were measured using a high performance liquid chromatograph (manufactured by Shimadzu Corporation, LC-10A). In addition, HFIP-806M (2 pieces) manufactured by Showa Denko Co., Ltd. was connected in series with the column, the measurement conditions were a temperature of 40 ° C., and the sample was a 0.05 wt% hydroxyfluoroisopropanol (HFIP) solution (0.45 μm filter). Filtered), the injection volume was 100 μL, the carrier solvent was HFIP containing 0.68 g of sodium trifluoroacetate (TFA) per liter, and standard polymethyl methacrylate was used as a calibration sample. As a result of measurement, the ratio of those having a molecular weight of 100,000 to 5,000,000 was 40% by weight. The obtained modified polyvinyl acetal resin was used as a binder resin for a coating paste.

(Preparation of conductive paste)
7 parts by weight of the obtained binder resin and 60 parts by weight of α-terpineol are added to 100 parts by weight of nickel fine particles (Mitsui Metals Co., Ltd., “2020SS”) as a conductive powder, and kneaded with three rolls to form a conductive paste. Got. The kneading was performed by passing a roll until no aggregate (uncrushed material) was observed with an optical microscope.

(Production of ceramic paste)
7 parts by weight of the obtained binder resin and 60 parts by weight of α-terpineol with respect to 100 parts by weight of barium titanate having an average particle size of 0.3 μm as ceramic powder (“BT-03” manufactured by Sakai Chemical Industry Co., Ltd.) In addition, the paste was kneaded for 48 hours using a ball mill to obtain a ceramic paste.

(Production of glass paste)
100 parts by weight of lead oxide-boron oxide-silicon oxide-aluminum oxide glass powder (lead oxide: 66 wt%, boron oxide: 5 wt%, silicon oxide: 24 wt%, aluminum oxide: 5 wt%) as glass powder On the other hand, 5 parts by weight of the obtained binder resin and 30 parts by weight of α-terpineol were added and mixed with a ball mill to obtain a glass paste.

(Example 2)
Polyethylene butyral resin not modified with ethylene in which the ratio between the modified polyvinyl acetal resin obtained in Example 1 and a molecular weight of 100,000 to 5,000,000 is 25% by weight (manufactured by Sekisui Chemical Co., Ltd., ESREC B “BM-S”) ) In a weight ratio of 6: 4, and the conductive resin, ceramic paste, and glass paste were used in the same manner as in Example 1 except that the obtained mixed resin was used as the binder resin of the coating paste. Got.

(Comparative Example 1)
A conductive paste, a ceramic paste, and a glass paste were obtained in the same manner as in Example 1 except that commercially available ethyl cellulose (manufactured by Dow Chemical Company, “STD45 type”) was used as a binder resin for the coating paste.

(Comparative Example 2)
An ethylene-unmodified polyvinyl butyral resin (Sekisui Chemical Co., Ltd., ESREC B "BM-S") having a molecular weight of 100,000 to 5 million is 25% by weight was used as a binder resin for the coating paste. Except for the above, conductive paste, ceramic paste and glass paste were obtained.

(Evaluation)
The conductive paste, ceramic paste, and glass paste prepared in Examples 1 and 2 and Comparative Examples 1 and 2 were evaluated by the following methods. The number of kneading times when producing the conductive paste was 3 times in Examples 1 and 2 and 5 times in Comparative Examples 1 and 2.
The results are shown in Table 1.

(1) Evaluation of conductive paste (1-1) Viscosity evaluation Using an E-type viscometer, the viscosity of the conductive paste was measured under the conditions of temperature: 25 ° C. and shear rate: 50 s ⁻¹ .

(1-2) Screen Printability Evaluation of Conductive Paste Using a 300-mesh polyester plate, when a line pattern of 20 lines / cm was continuously printed, the number of printing failures was counted. .

(1-3) Evaluation of Thermal Decomposability and Delamination Generation of Ceramic Green Sheet Laminate 10 parts by weight of polyvinyl butyral resin (manufactured by Sekisui Chemical Co., Ltd., ESREC B “BM-S”, degree of polymerization 800) is 30 parts by weight of toluene. And 15 parts by weight of ethanol in a mixed solvent and dissolved by stirring. Further, 3 parts by weight of dibutyl phthalate as a plasticizer was added and dissolved by stirring. To the obtained resin solution, 100 parts by weight of barium titanate (“BT-03 (average particle size: 0.3 μm)” manufactured by Sakai Chemical Industry) as ceramic powder was added and mixed for 48 hours with a ball mill to obtain a ceramic slurry composition. Obtained. The obtained ceramic slurry composition was applied onto a release-treated polyester film so that the thickness after drying was about 5 μm, air-dried at room temperature for 1 hour, a hot-air dryer at 80 ° C. for 3 hours, and then And dried at 120 ° C. for 2 hours to obtain a ceramic green sheet.

A ceramic green sheet is cut into a 5 cm square size, 100 sheets of the conductive paste obtained by screen printing are stacked, and bonded under a thermocompression condition of 70 ° C. and 150 kg / cm ² for 10 minutes. A ceramic green sheet laminate was obtained.
The obtained ceramic green sheet laminate was heated to 450 ° C. at a temperature rising rate of 3 ° C./min in a nitrogen atmosphere, held for 5 hours, and further heated to 1350 ° C. at a temperature rising rate of 5 ° C./min. The ceramic sintered body was obtained by holding for a time. The obtained ceramic sintered body was visually observed, and the thermal decomposability of the ceramic green sheet laminate was evaluated according to the following criteria.
○: Sintered uniformly, and nothing other than ceramic powder is observed. △: Some black dots are rarely found in the sheet. ×: Black dots are found in the sheet. Pretty much confirmed

Further, after cooling this sintered body to room temperature, it was divided in half, the state of the sheet in the vicinity of 50 layers was observed with an electron microscope, the presence or absence of delamination between the ceramic layer and the conductive layer was observed, and according to the following criteria: Adhesion was evaluated.
○: No delamination ×: Delamination

(1-4) Evaluation of adhesiveness The conductive paste was applied on a polyethylene terephthalate film so as to have a thickness of 10 μm after drying and a size of 1 cm square, and produced on this by evaluation (1-3). Ceramic green sheets were laminated and thermocompression bonded for 3 seconds under conditions of a temperature of 80 ° C. and a pressure of 39 kg / cm ² to prepare a laminate. The peel strength when the obtained laminate was peeled off at a rate of 0.49 mm / second was measured using an adhesive strength measuring device during heating (FCL 009 type, manufactured by Fuji Cobian).

(2) Evaluation of Ceramic Paste (2-1) Evaluation of Screen Printability of Ceramic Paste 10 parts by weight of polyvinyl butyral resin (Sekisui Chemical Co., Ltd., ESREC B “BM-S”, degree of polymerization 800) is 30 wt. In addition to a mixed solvent of 15 parts by weight of ethanol and dissolved by stirring, 3 parts by weight of dibutyl phthalate was added as a plasticizer and dissolved by stirring. To the obtained resin solution, 100 parts by weight of barium titanate (“BT-03 (average particle size: 0.3 μm)” manufactured by Sakai Chemical Industry Co., Ltd.) as ceramic powder was added and mixed for 48 hours with a ball mill to produce a ceramic slurry composition. Got. The obtained slurry composition was applied onto a release-treated polyester film so that the thickness after drying was about 10 μm, air-dried at room temperature for 1 hour, a hot-air dryer at 80 ° C. for 3 hours, then A ceramic green sheet was obtained by drying at 120 ° C. for 2 hours.

Using a screen printing machine (Mino Group, Mino mat Y-3540) and SX screen plate (SX300B), ceramic paste was screen printed on the ceramic green sheet, and the printed surface was observed visually or with a magnified microscope. The screen printability was evaluated according to the following criteria.
◯: No thread-like ceramic paste was observed on the printed surface ×: Thread-like ceramic paste was observed on the printed surface

(2-2) Manufacture of multilayer ceramic capacitor 7 parts by weight of binder resin and 60 parts by weight of α-terpineol were added to and mixed with 100 parts by weight of nickel powder (Mitsui Metals Co., Ltd., 2020SS), and then kneaded with three rolls. Thus, a conductive paste was prepared.
A ceramic green sheet produced by the same method as in Evaluation (2-1) was cut into a size of 5 cm square, and the resulting conductive paste was applied by screen printing. Next, the ceramic paste was applied by screen printing to a portion of the ceramic green sheet where the conductive paste was not applied.
100 coated ceramic green sheets were stacked and pressed under conditions of thermocompression bonding at a temperature of 70 ° C. and a pressure of 150 kg / cm ² for 10 minutes to obtain a ceramic green sheet laminate.
The obtained ceramic green sheet laminate was heated to 450 ° C. at a temperature rising rate of 3 ° C./min in a nitrogen atmosphere, held for 5 hours, and further heated to 1350 ° C. at a temperature rising rate of 5 ° C./min. A multilayer ceramic capacitor was obtained by holding for a time.
After cooling the obtained multilayer ceramic capacitor to room temperature, it was divided in half, and the state of the sheet in the vicinity of 50 layers was observed with an electron microscope to evaluate the presence or absence of delamination.

(3) Evaluation of glass paste (3-1) Evaluation of alkali resistance A glass paste was coated on a glass substrate and dried at 100 ° C. for 60 minutes. After drying, a photosensitive resist film was laminated, and then exposed at 250 mJ / cm ² through a 1 mm pitch pattern. Subsequently, it was immersed in a 0.5% aqueous sodium hydrogen carbonate solution, the state of the coating film was observed for 300 seconds, and evaluated according to the following criteria.
◯: No change was observed in the coating film.
X: Peeling of the resist film and partial peeling of the glass film were observed.

According to the present invention, the inorganic powder such as conductive powder, ceramic powder and glass powder is excellent in dispersibility,
A coating paste capable of exhibiting extremely excellent coating properties and printing properties can be provided.

Claims (5)

A coating paste containing a binder resin composed of a polyvinyl resin, an organic solvent and an inorganic powder,
The coating paste according to claim 1, wherein the polyvinyl resin has a molecular weight ratio of 100,000 to 5,000,000. The coating paste according to claim 1, wherein the polyvinyl resin is a polyvinyl acetal resin and / or a modified polyvinyl acetal resin. 3. The coating paste according to claim 2, wherein the modified polyvinyl acetal resin comprises structural units represented by the following general formulas (1), (2), (3) and (4).

In the formula, R ¹ represents a linear or branched alkyl group having 1 to 20 carbon atoms, and R ² represents hydrogen, a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, or an aryl group. To express. N represents an integer of 1 to 8. Further, in the modified polyvinyl acetal resin, the content of the structural unit represented by the general formula (3) is 1 to 20 mol%, and the content of the structural unit represented by the general formula (4) is 30 to 78 mol%. is there. Content of the structural unit represented by General formula (2) is 20-30 mol%, The coating paste of Claim 3 characterized by the above-mentioned. R ² is, CH ₃ and / or _C 3, characterized in that a _{H 7} claim 3 or 4, wherein the coating paste.