JP2005243333A - Conductive paste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive paste, for use for ceramic electronic components, with dispersion of metal powder in it stable over time, and also, having smaller viscosity change over time. <P>SOLUTION: Of the conductive paste containing conductive powder, an anionic polymer dispersant, a nonion polymer binder, and an organic solvent, the anion polymer dispersant is an acrylic copolymer with a weight average molecular weight of 1,000 to 200, 000 with an unsaturated carboxylic acid part, and that, the nonion polymer binder, mainly composed of (meta)acrylic ester, is a poly(meta) acrylate copolymer with a weight average molecular weight of 10,000 to 800,000. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a conductive paste used for a ceramic electronic component such as a multilayer ceramic capacitor.

  The conductive paste used for forming an electrode of a ceramic electronic component is obtained by dispersing conductive metal powder in an organic vehicle obtained by dissolving a resin component serving as an organic binder in an organic solvent. Cellulose resins such as ethyl cellulose and nitrocellulose are used as the organic binder, and terpineol, benzyl alcohol, butyl carbitol acetate, methyl ethyl ketone, and the like are used as the organic solvent.

However, an electroconductive paste is formed using an organic binder mainly composed of a cellulose-based resin and a metal powder such as copper, and this is baked on both end faces of a laminate composed of a ceramic layer and an internal electrode to form external electrodes. When the conductive paste was formed, the thermal decomposability of the conductive paste was poor, and firing in a reducing atmosphere with a low firing temperature caused a problem that the carbon component remained in the external electrode even after firing. Moreover, the problem that the electroconductivity of an external electrode fell also arose. Therefore, it has been proposed to use an acrylic resin excellent in thermal decomposability as an organic binder (see Patent Document 1).
JP 59-199778 A

  However, when a conductive paste is formed using this acrylic resin as the main component of the organic binder, the thermal decomposability of the conductive paste is improved, but the amount of adsorption of the acrylic resin to the metal powder in the paste changes over time. However, there is a problem that the viscosity of the conductive paste gradually changes immediately after production because a three-dimensional network structure is formed over time due to a crosslinking reaction between the acrylic resin and the charged metal powder. is there.

  In addition, with the recent increase in thickness of ceramic electronic components, the average particle size of the metal powder used in the conductive paste tends to be small, and the change in viscosity over time of the conductive paste tends to become more prominent. is there.

  Further, since the viscosity of the conductive paste gradually changes, there is a problem that application workability is deteriorated and it is difficult to stably obtain a desired electrode shape with time.

  Accordingly, an object of the present invention is to provide a conductive paste for use in ceramic electronic components, in which the dispersion of metal powder in the conductive paste is stable over time and the viscosity change over time is small. Is to try to provide.

  In order to achieve the above object, the conductive paste of the present invention is a conductive paste containing a conductive powder, an anionic polymer dispersant, a nonionic polymer binder, and an organic solvent. It is an acrylic copolymer having an unsaturated carboxylic acid moiety and a weight average molecular weight of 1,000 to 200,000, and the nonionic polymer binder has a (meth) acrylic acid ester as a main component and a weight average molecular weight of 10,000 to 800,000. It is characterized by being a poly (meth) acrylate copolymer.

  The anionic polymer dispersant contains 0.5 to 50% by weight of carboxylic acid in one molecule.

  Further, the nonionic polymer binder is characterized by containing 0.5 to 50% by weight of a glycidyl group and / or a hydroxyl group in one molecule.

  According to the present invention, a conductive paste having a small change in viscosity over time can be obtained, the workability of coating can be improved, and a desired electrode shape can be stably obtained over time in a ceramic electronic component.

  Hereinafter, the conductive paste of the present invention will be described.

  FIG. 1 is a cross-sectional view of a ceramic electronic component formed using the conductive paste of the present invention. Here, 2 is a laminate, 3 is a ceramic layer, 4 and 5 are internal electrode layers, and 8 and 9 are external electrodes.

  In the conductive paste of the present invention, an anionic polymer dispersant having an acid point is used as a base generated by an oxide film in order to improve the dispersibility of the metal powder in the conductive paste and reduce the change in viscosity over time. It is characterized in that it is adsorbed on the surface of a metal powder having a point, and is combined with a nonionic polymer binder that hardly reacts with the anionic polymer dispersant and is excellent in thermal decomposability.

  Since the anionic polymer dispersant itself is bulky, the metal powder adsorbed by the anionic polymer dispersant is three-dimensionally removed from other metal powders present in the vicinity of the metal powder in the conductive paste by its steric exclusion action. By being hindered, the dispersibility in the conductive paste is stabilized.

  Here, since the anionic polymer dispersant coats the surface of the metal powder, it is added excessively in an amount more than necessary for coating. At that time, if a polymer binder that easily reacts with the anionic polymer dispersant is present in the conductive paste, an excess of the anionic polymer dispersant that was not used for coating the metal powder and the polymer binder A cross-linking reaction or the like may occur, and the viscosity of the conductive paste may change over time, or the conductive paste itself may gel.

  In order to solve such a problem, a nonionic polymer binder that hardly reacts with the anionic polymer dispersant is used as the polymer binder used in the conductive paste of the present invention.

  Here, since the nonionic polymer binder is difficult to be adsorbed to the metal powder, the anionic polymer dispersant is preferentially adsorbed to the metal powder even when mixed with the anionic polymer dispersant.

  The nonionic polymer binder used in the conductive paste of the present invention is preferably an acrylic copolymer mainly composed of (meth) acrylic acid ester. Here, the monomer as the main component is preferably an alkyl (meth) acrylate having 1 to 8 carbon atoms that is excellent in thermal decomposability. Among these, it is more preferable that the main component is methacrylate having excellent thermal decomposability. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t -Butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-hydroxy (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) Examples include, but are not limited to, acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, and 1,6-hexanediol (meth) acrylate. Two or more of these monomers may be used in combination. In addition, examples of the copolymerizable monomer include acrylonitrile, acrylamide, N-methylacrylamide, styrene, α-methylstyrene, ethylene, vinyl chloride, and the like.

  Moreover, in order for the said monomer to become a base part of a nonionic polymer binder, it is preferable that 50 weight% or more is contained in the copolymer of a nonionic polymer binder as a main component. Further, a (meth) acrylic acid ester monomer in which a glycidyl group and / or a hydroxyl group is introduced into an alkyl group is used as a monomer for the nonionic polymer binder. These two types of functional groups are nonionic, but have polarity, and the cohesive force as a polymer binder becomes strong. The content of the (meth) acrylic acid ester monomer in which a glycidyl group and / or a hydroxyl group is introduced into the alkyl group is 0.5 to 50% by weight with respect to the nonionic polymer binder copolymer. It is preferable. Here, if the content of the (meth) acrylic acid ester monomer is less than 0.5% by weight, the effect of the functional group is not exhibited, and if it exceeds 50% by weight, the cohesion as a polymer binder is strong. Therefore, when the copolymer of the nonionic polymer binder is formed, it is gelled or the viscosity becomes high, so that the workability of applying the conductive paste is remarkably deteriorated.

  Examples of the monomer containing a glycidyl group include glycidyl (meth) acrylate, allyl glycidyl ether, glycidyl ethyl acrylate, crotonyl glycidyl ether, glycidyl crotonate, and glycidyl isocrotonate. Examples of the monomer containing a hydroxyl group include 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate.

  The nonionic polymer binder preferably has a weight average molecular weight in the range of 10,000 to 800,000. When the weight average molecular weight is 10,000 or more, coating workability in screen printing or the like is improved. Furthermore, if it is 50000 or more, the thixotropic property is exhibited in the conductive paste itself, so that the coating workability is improved. However, if the weight average molecular weight exceeds 800,000, it is not preferable because the conductive paste exhibits spinnability and causes problems such as poor release from the printing pattern during screen printing. On the other hand, when the weight average molecular weight is less than 10,000, the viscosity of the conductive paste itself decreases, and it becomes difficult to maintain a desired coating shape during the coating operation.

  In addition, although the manufacturing method of the monomer of the said nonionic polymer binder is not specifically limited, In order to control a weight average molecular weight in the range of 10,000-800000, it is preferable to use solution polymerization.

  The anionic polymer dispersant used in the present invention is preferably an acrylic copolymer having an unsaturated carboxylic acid moiety because a (meth) acrylate copolymer is used as a nonionic polymer binder. Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, vinyl acetate, and acid anhydrides thereof. The content of the unsaturated carboxylic acid part relative to the acrylic copolymer is preferably 0.5 to 50% by weight. Here, when the content of the unsaturated carboxylic acid moiety is less than 0.5% by weight, the density of the acid sites is small, so that the anionic polymer dispersant is difficult to adsorb on the metal powder. In addition, when the content exceeds 50% by weight, the density of acid sites is increased, and the anionic polymer dispersant adsorbed on the metal powder is not so bulky, and the anionic polymer dispersion The steric exclusion action of the agent is undesirably small.

  Moreover, as a weight average molecular weight of an anionic polymer dispersing agent, the range of 1000-200000 is preferable. Here, when the molecular weight is small, the wettability is excellent and the adsorption rate to the metal powder is increased. However, when the weight average molecular weight is less than 1000, the steric exclusion action when adsorbed to the metal powder is reduced, and the conductive property is reduced. The dispersion stability in the conductive paste will be reduced. In addition, when the molecular weight is large, the anionic polymer dispersant itself becomes bulky, and the adsorption rate to the metal powder becomes slow, but once adsorbed, the steric exclusion action is large, and the metal powder in the conductive paste The dispersion stability of is improved. However, when the weight average molecular weight exceeds 200,000, the adsorption density of the anionic polymer dispersant on the surface of the metal powder is reduced, and the dispersion stability of the metal powder in the conductive paste is lowered.

  The amount of the anionic polymer dispersant added to the conductive paste is preferably added in excess of the amount necessary for coating the metal powder. Generally, about 0.5 to 5.0% by weight is preferable with respect to the weight of the metal powder before coating.

  The organic solvent used in the conductive paste of the present invention is preferably an organic solvent having a boiling point of 150 ° C. or higher and 250 ° C. or lower as the main solvent in consideration of the coating and drying properties of the conductive paste. Specifically, terpineol, dihydroterpineol, dihydroterpineol acetate, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol Monobutyl ether acetate, 2,2,4-trimethyl-1,3-pentadiol monoisobutyrate, isophorone, 3-methoxybutyl acetate, benzyl alcohol, 1-octanol, 1-nanool, 2-ethyl-1-hexanol, 1-decanol, 1-undecanol, 1,2-ethanediol, 1,2-propane All, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentadiol, aromatic or aliphatic hydrocarbons having a boiling point of 150 ° C. or higher, Examples thereof include phthalic acid esters such as butyl lactate, dibutyl phthalate and dioctyl phthalate, and adipic acid esters such as dibutyl adipate and dioctyl adipate. Moreover, the said organic solvent can be used individually, and can be used even if it mixes 2 or more types. When two or more kinds of organic solvents are mixed, organic solvents having a boiling point of 150 ° C. or lower can be mixed and used. Specific examples of the organic solvent having a boiling point of 150 ° C. or lower include aromatics such as toluene and xylene, and ketones such as methyl ethyl ketone and methyl isobutyl ketone.

  Further, in order to improve the dispersion of the metal powder in the conductive paste as appropriate, in addition to the anionic polymer dispersant, a different dispersant may be added, or the adhesive force between the laminate and the electrode after firing. It is also possible to add glass frit in order to increase the thickness. It is also possible to add a thixotropic agent or the like in order to adjust or maintain the coating shape when the conductive paste is applied to the laminate. In addition, a metal resinate can be added to control the sinterability of the conductive paste.

  The conductive paste of the present invention can be used for multilayer ceramic electronic components such as multilayer ceramic capacitors, multilayer ceramic inductors, and thermistors. Moreover, it can be used not only for multilayer ceramic electronic components but also for single-plate ceramic electronic components.

Hereinafter, as an embodiment of the present invention, a conductive paste and a multilayer ceramic capacitor will be produced and specifically described.
(Experimental example 1)
(A) Synthesis of anionic polymer dispersant Toluene was charged as a solvent in a 1 liter separable flask equipped with a nitrogen gas introduction tube, a reflux device, a thermometer, and a stirring function, and heated while bubbling nitrogen gas. Next, acrylic acid, 2-ethylhexyl methacrylate, and methyl methacrylate prepared as raw materials were mixed in a ratio of 10% by weight of acrylic acid, 50% by weight of 2-ethylhexyl methacrylate, and 40% by weight of methyl methacrylate, and After adding and mixing benzoyl peroxide as a polymerization initiator, it was dropped into toluene in the separable flask. Next, after stirring for 2 hours while controlling the reaction temperature, foreign substances were removed using a # 200 mesh to obtain an anionic polymer dispersant. In this synthesis, anionic polymer dispersants having different weight average molecular weights shown in Table 1 were obtained by varying the amount of the polymerization initiator and the reaction temperature.

(B) Synthesis of nonionic polymer binder As in (a) above, toluene was charged as a solvent in a 1-liter separable flask equipped with a nitrogen gas inlet tube, a reflux device, a thermometer, and a stirring function, and nitrogen gas was bubbled. While warming. Next, glycidyl methacrylate, ethyl methacrylate, methyl acrylate and methyl methacrylate as glycidyl group-containing (meth) acrylic acid ester prepared as a raw material, glycidyl methacrylate 10% by weight, ethyl methacrylate 50% by weight, After mixing at a ratio of 20% by weight of methyl acrylate and 20% by weight of methyl methacrylate, benzoyl peroxide was added and mixed as a polymerization initiator, the mixture was dropped into toluene in the separable flask. Next, after stirring for 2 hours while controlling the reaction temperature, foreign matters were removed using a # 200 mesh to obtain a nonionic polymer binder. In this synthesis, by varying the amount of the polymerization initiator and the reaction temperature, the anionic polymer dispersants having different weight average molecular weights shown in Sample Nos. 1 to 9 in Table 1 were obtained.

Further, 10% by weight of 2-hydroxymethacrylate, which is a hydroxyl group-containing (meth) acrylate, 50% by weight of ethyl methacrylate, 20% by weight of methyl acrylate, and 20% by weight of methyl methacrylate are mixed together as a polymerization initiator. After adding and mixing benzoyl peroxide, it was added dropwise to toluene in the separable flask. Next, after stirring for 2 hours while controlling the reaction temperature, foreign matter was removed using a # 200 mesh to obtain a nonionic polymer binder having a weight average molecular weight of the value shown in Sample No. 10 of Table 1. .
(C) Preparation of conductive paste for internal electrode An organic vehicle was obtained by mixing 80 parts by weight of terpineol as an organic solvent and 20 parts by weight of the nonionic polymer binder prepared in (b).

Next, 100 parts by weight of nickel powder as a metal powder, 1 part by weight of the anionic polymer dispersant prepared in (a) and 50 parts by weight of the organic vehicle were mixed, and then a three-roll mill was used. Dispersion was performed, and conductive pastes for internal electrodes of sample numbers 1 to 10 were obtained.
(D) Preparation of conductive paste for external electrode 100 parts by weight of copper powder as metal powder, 35 parts by weight of organic vehicle prepared in (c) as organic binder, and anionic polymer prepared in (a) After mixing 1 part by weight of the dispersant and 6 parts by weight of borosilicate glass as a glass frit, the mixture was dispersed using a three-roll mill to obtain conductive pastes for external electrodes of sample numbers 1 to 10.

Here, regarding the method for producing each conductive paste, a three-roll mill was used in the present invention. Can be used as appropriate.
(E) Production of multilayer ceramic capacitor On the ceramic green sheet mainly composed of barium titanate, the conductive paste for internal electrodes produced in the above (c) is printed so as to have a desired pattern by screen printing. And dried at 80 ° C. for 10 minutes. Next, 10 green sheets on which the internal electrode conductive paste is not printed are stacked, and 200 ceramic green sheets on which the internal electrode conductive paste is printed are stacked in the stacking direction. Ten green sheets on which no adhesive paste was printed were laminated. Next, this was thermocompression bonded under pressure conditions of 80 ° C. and 9.8 × 10 ⁷ Pa to form an unfired laminate. This unfired laminate was cut so that the dimensions after firing were 3.2 mm long × 1.6 mm wide × 1.6 mm thick to obtain an unfired laminate chip. Here, the conductive paste for internal electrodes is also printed so as to have a shape matched to an unfired laminated chip having a length of 3.2 mm and a width of 1.6 mm.

  Next, these were aligned on a setter for firing in which a small amount of zirconia powder was dispersed, and the temperature was raised from room temperature to 250 ° C. over 24 hours to remove the binder component from the unfired laminate. Next, it was put into a firing furnace and fired at a maximum temperature of 1250 ° C. with a total profile of about 20 hours including firing for 2 hours to obtain a fired laminate.

  The fired laminate was put into a barrel, subjected to end face polishing, and then both end faces of the fired laminate were immersed in a conductive paste tank for external electrodes to prepare the external electrode prepared in (d). A conductive paste was applied. The laminate coated with the external electrode conductive paste was dried at 100 ° C. for 30 minutes. Next, heat treatment was performed at 900 ° C. for 15 minutes in a nitrogen atmosphere, and the conductive paste for external electrodes was baked to produce multilayer ceramic capacitors of sample numbers 1 to 10.

  In the above examples, after obtaining the fired laminate, the external electrode conductive paste was applied to both end faces of the fired laminate and baked to form external electrodes. A method may be used in which the external electrode is formed by applying the conductive paste for the external electrode before firing the multilayer chip and simultaneously firing the unfired multilayer chip and the conductive paste for external electrode.

Next, the following characteristics were evaluated using the internal electrode conductive paste, the external electrode conductive paste, and the multilayer ceramic capacitor of Sample Nos. 1 to 10, and the results are shown in Table 1.
(Characteristic evaluation items)
(Initial viscosity)
The viscosity (Pa · s) of each conductive paste immediately after production was measured using an E-type viscometer (manufactured by Tokyo Keiki Co., Ltd.) at 20 ° C. and 2.5 rpm.
(Dispersity)
The particle size distribution of each conductive paste was measured and calculated using an optical diffraction particle size distribution measuring device. First, each metal powder prepared above, in ethanol and dispersed using an ultrasonic homogenizer, the particle size of the metal powder by applying an ultrasonic wave to the point where not more smaller, particle diameters at a D ₉₀ at that time Was recorded as the critical particle size of each metal powder. Further, each conductive paste was diluted with a mixed solution of toluene / ethanol = 50/50 vol%, and the particle size of D _{90 in} the particle size distribution was recorded, and this was used as the particle size of each conductive paste. Then, the degree of dispersion was calculated using Equation 1 below.
Formula 1: Dispersity = (particle diameter of each conductive paste / limit particle diameter of each metal powder) -1
If the value of the dispersity is +, the closer the value is to 0, the better the dispersibility. If the numerical value is-, the larger the absolute value, the better the dispersibility.
(Pyrolysis temperature)
The organic binder added to each conductive paste was dried at 80 ° C. for 24 hours, and the temperature at which the weight of the organic binder was halved using a TGA (thermobalance) was measured. did.
(Viscosity change rate)
The value calculated based on Equation 2 shown below was taken as the viscosity change rate (%).
Formula 2: Viscosity change rate (%) = {(viscosity after 60 days / initial viscosity) / (initial viscosity)} × 100
(Printability)
When screen printing was performed on each conductive paste, the plate separation was good and continuous printing was possible. Further, when the plate separation was poor and continuous printing could not be performed, or when the conductive paste had a low viscosity and the printed pattern was smeared or blurred after printing, it was rated as x.

  From the above characteristic evaluation, when the conductive paste can be used without any problem, “circle” is indicated in the “judgment” column of Table 1, and when the problem occurs and it cannot be used, “×” is described. As shown in Table 1, it was found that sample numbers 1 to 5 and 10 satisfying the scope of the present invention can stably perform continuous printing.

Sample Nos. 6 to 8 which are out of the scope of the present invention have a problem in printability because continuous printing cannot be performed, and the viscosity change rate is very large. It turned out to be difficult. Also, for sample number 9 which is also outside the scope of the present invention, although the rate of change in viscosity was equivalent to sample numbers 1 to 5 and 10, the initial viscosity was low, so after printing, at the periphery of the printed figure It was found that blurring occurred and printability was poor.
(Experimental example 2)
(F) Synthesis of anionic polymer dispersant Toluene was charged as a solvent into a 1 liter separable flask equipped with a nitrogen gas introduction tube, a reflux device, a thermometer, and a stirring function, and heated while bubbling nitrogen gas. Next, acrylic acid, 2-ethylhexyl methacrylate, and methyl methacrylate prepared as raw materials were mixed in the proportions shown in Table 2, and after adding and mixing benzoyl peroxide as a polymerization initiator, the separable flask In toluene. Next, after stirring for 2 hours while controlling the reaction temperature, an anionic polymer dispersant having a polymerization average molecular weight of 50000 was obtained by removing foreign matter using a # 200 mesh.

(G) Synthesis of nonionic polymer binder As in (f) above, toluene was charged as a solvent into a 1-liter separable flask equipped with a nitrogen gas inlet tube, reflux apparatus, thermometer, and stirring function, and nitrogen gas was bubbled. While warming. Next, glycidyl methacrylate, ethyl methacrylate, methyl acrylate and methyl methacrylate as glycidyl group-containing (meth) acrylic acid ester prepared as a raw material, glycidyl methacrylate 10% by weight, ethyl methacrylate 50% by weight, After mixing at a ratio of 20% by weight of methyl acrylate and 20% by weight of methyl methacrylate, benzoyl peroxide was added and mixed as a polymerization initiator, the mixture was dropped into toluene in the separable flask. Next, after stirring for 2 hours while controlling the reaction temperature, foreign matters were removed using a # 200 mesh to obtain a nonionic polymer binder having a polymerization average molecular weight of 200,000.
(H) Preparation of conductive paste for internal electrode An organic vehicle was obtained by mixing 80 parts by weight of terpineol as an organic solvent and 20 parts by weight of the nonionic polymer binder prepared in (g).

Next, 100 parts by weight of nickel powder as a metal powder, 1 part by weight of the anionic polymer dispersant prepared in (f) and 50 parts by weight of the organic vehicle were mixed, and then a three-roll mill was used. The conductive paste for internal electrodes of sample numbers 11 to 15 was obtained.
(I) Preparation of conductive paste for external electrode 100 parts by weight of copper powder as metal powder, 35 parts by weight of organic vehicle prepared in (h) as organic binder, and anionic polymer prepared in (f) After mixing 1 part by weight of a dispersant and 6 parts by weight of borosilicate glass as a glass frit, the mixture was dispersed using a three-roll mill to obtain conductive pastes for external electrodes of sample numbers 11 to 15.
(J) Production of Multilayer Ceramic Capacitor As in (e) above, a ceramic green sheet, an internal electrode conductive paste produced in (h), and an external electrode conductive paste produced in (i). Using this, a multilayer ceramic capacitor was produced.

  Next, using the conductive paste for internal electrodes, the conductive paste for external electrodes, and the multilayer ceramic capacitor of Sample Nos. 11 to 15, initial viscosity, dispersity, thermal decomposition temperature, rate of change in viscosity, and printability Evaluation was performed and the results are shown in Table 2.

  From the above characteristic evaluation, when the conductive paste could be used without any problem, “circle” was written in the “judgment” column of Table 2, and “x” was written when the problem occurred and it could not be used. As shown in Table 2, it was found that Sample Nos. 12 to 14 satisfying the scope of the present invention can stably perform continuous printing.

Sample No. 15, which is outside the scope of the present invention, has a problem in printability because continuous printing cannot be performed, and the viscosity change rate is very large, so that a desired electrode shape can be obtained stably over time. It turned out to be difficult. For sample No. 11 which is also outside the scope of the present invention, the rate of change in viscosity was equivalent to that of sample Nos. 12 to 14, but since the initial viscosity was low, blurring occurred at the periphery of the printed figure after printing. And it turned out that printability was bad.
(Experimental example 3)
(K) Synthesis of Anionic Polymer Dispersant Toluene was charged as a solvent in a 1 liter separable flask equipped with a nitrogen gas introduction tube, a reflux device, a thermometer, and a stirring function, and heated while bubbling nitrogen gas. Next, acrylic acid, 2-ethylhexyl methacrylate, and methyl methacrylate prepared as raw materials were mixed in a proportion of 10% by weight of acrylic acid, 45% by weight of 2-ethylhexyl methacrylate, and 35% by weight of methyl methacrylate, and After adding and mixing benzoyl peroxide as a polymerization initiator, it was dropped into toluene in the separable flask. Next, after stirring for 2 hours while controlling the reaction temperature, an anionic polymer dispersant having a polymerization average molecular weight of 50000 was obtained by removing foreign matter using a # 200 mesh.
(L) Synthesis of nonionic polymer binder As in (k) above, toluene was charged as a solvent into a 1-liter separable flask equipped with a nitrogen gas inlet tube, a reflux device, a thermometer, and a stirring function, and nitrogen gas was bubbled. While warming. Next, glycidyl methacrylate, ethyl methacrylate, methyl acrylate, and methyl methacrylate as glycidyl group-containing (meth) acrylic acid esters prepared as raw materials were mixed in the proportions shown in Table 3, and benzoyl was used as a polymerization initiator. After adding peroxide and mixing, it was dropped into toluene in the separable flask. Next, after stirring for 2 hours while controlling the reaction temperature, foreign matters were removed using a # 200 mesh to obtain a nonionic polymer binder having a polymerization average molecular weight of 200,000.

(M) Preparation of conductive paste for internal electrode An organic vehicle was obtained by mixing 80 parts by weight of terpineol as an organic solvent and 20 parts by weight of the nonionic polymer binder prepared in (l).

Next, 100 parts by weight of nickel powder as a metal powder, 1 part by weight of the anionic polymer dispersant prepared in (k) and 50 parts by weight of the organic vehicle are mixed, and then a three-roll mill is used. The conductive paste for internal electrodes of sample numbers 16 to 20 was obtained.
(N) Preparation of conductive paste for external electrode 100 parts by weight of copper powder as metal powder, 35 parts by weight of organic vehicle prepared in (m) as organic binder, and anionic polymer prepared in (k) After mixing 1 part by weight of a dispersant and 6 parts by weight of borosilicate glass as a glass frit, the mixture was dispersed using a three-roll mill to obtain a conductive paste for external electrodes of sample numbers 16 to 20.
(O) Production of Multilayer Ceramic Capacitor As in (j) above, the ceramic green sheet, the internal electrode conductive paste produced in (m), and the external electrode conductive paste produced in (n). Using this, a multilayer ceramic capacitor was produced.

  Next, using the conductive paste for internal electrodes, the conductive paste for external electrodes, and the multilayer ceramic capacitor of Sample Nos. 16 to 20, the initial viscosity, dispersity, thermal decomposition temperature, rate of change in viscosity, and printability Evaluation was performed and the results are shown in Table 3.

  From the above characteristic evaluation, when the conductive paste could be used without any problem, “circle” was written in the “judgment” column of Table 3, and when the problem occurred and it could not be used, x was written. As shown in Table 3, it was found that Sample Nos. 17 to 19 satisfying the scope of the present invention can stably perform continuous printing.

Sample No. 20, which is outside the scope of the present invention, has a problem in printability because continuous printing cannot be performed, and the viscosity change rate is very large, so that a desired electrode shape can be obtained stably over time. It turned out to be difficult. For sample No. 16, which is also outside the scope of the present invention, the rate of change in viscosity was equivalent to that of sample Nos. 17 to 19, but the initial viscosity was low, so that blurring occurred at the periphery of the printed figure after printing. And it turned out that printability was bad.
(Experimental example 4)
(P) Synthesis of Anionic Polymer Dispersant Toluene was charged as a solvent into a 1 liter separable flask equipped with a nitrogen gas introduction tube, a reflux device, a thermometer, and a stirring function, and heated while bubbling nitrogen gas. Next, acrylic acid, 2-ethylhexyl methacrylate, and methyl methacrylate prepared as raw materials were mixed in a proportion of 10% by weight of acrylic acid, 45% by weight of 2-ethylhexyl methacrylate, and 35% by weight of methyl methacrylate, and After adding and mixing benzoyl peroxide as a polymerization initiator, it was dropped into toluene in the separable flask. Next, after stirring for 2 hours while controlling the reaction temperature, foreign substances were removed using a # 200 mesh to obtain an anionic polymer dispersant having a polymerization average molecular weight of 50000.
(Q) Synthesis of nonionic polymer binder As in (p) above, toluene was charged as a solvent into a 1-liter separable flask equipped with a nitrogen gas inlet tube, a reflux device, a thermometer, and a stirring function, and nitrogen gas was bubbled. While warming. Next, 2-hydroxy methacrylate, ethyl methacrylate, methyl acrylate, and methyl methacrylate as hydroxyl-containing (meth) acrylic acid esters prepared as raw materials were mixed with 25% by weight of 2-hydroxy methacrylate and 45% of ethyl methacrylate. After mixing at a ratio of 15% by weight, 15% by weight of methyl acrylate, and 15% by weight of methyl methacrylate, benzoyl peroxide was added and mixed as a polymerization initiator, and then added dropwise to toluene in the separable flask. Next, after stirring for 2 hours while controlling the reaction temperature, foreign matters were removed using a # 200 mesh to obtain a nonionic polymer binder having a polymerization average molecular weight of 200,000.

(R) Preparation of conductive paste for internal electrode An organic vehicle was obtained by mixing 80 parts by weight of terpineol as an organic solvent and 20 parts by weight of the nonionic polymer binder prepared in (q).

Next, after mixing 100 parts by weight of nickel powder as metal powder, 1 part by weight of the anionic polymer dispersant prepared in (p) and 50 parts by weight of the organic vehicle, a three-roll mill is used. Thus, an internal electrode conductive paste of Sample No. 21 was obtained.
(S) Preparation of conductive paste for external electrode 100 parts by weight of copper powder as metal powder, 35 parts by weight of organic vehicle prepared in (r) as organic binder, and anionic polymer prepared in (p) After mixing 1 part by weight of the dispersant and 6 parts by weight of borosilicate glass as a glass frit, the mixture was dispersed using a three roll mill to obtain a conductive paste for external electrode of sample number 21.
(T) Production of Multilayer Ceramic Capacitor As in (o) above, a ceramic green sheet, an internal electrode conductive paste produced in (r), and an external electrode conductive paste produced in (s). Using this, a multilayer ceramic capacitor was produced.

  Next, using the conductive paste for internal electrode, the conductive paste for external electrode, and the multilayer ceramic capacitor of Sample No. 21, the initial viscosity, the degree of dispersion, the thermal decomposition temperature, the viscosity change rate, and the printability are evaluated. The results are shown in Table 4.

  From the above-mentioned characteristic evaluation, when the conductive paste could be used without any problem, “◯” was written in the “judgment” column of Table 4. As shown in Table 4, it was found that Sample No. 21 satisfying the scope of the present invention can stably perform continuous printing.

It is sectional drawing which shows one Example of the ceramic electronic component using the electrically conductive paste of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ceramic electronic component 2 Laminated body 3 Ceramic layer 4, 5 Internal electrode layer 8, 9 External electrode

Claims (3)

  In a conductive paste comprising a conductive powder, an anionic polymer dispersant, a nonionic polymer binder, and an organic solvent, the anionic polymer dispersant has an unsaturated carboxylic acid moiety and has a weight average molecular weight of 1,000 to 200,000. The nonionic polymer binder is a poly (meth) acrylate copolymer having a (meth) acrylic acid ester as a main component and a weight average molecular weight of 10,000 to 800,000. Conductive paste.   The conductive paste according to claim 1, wherein the anionic polymer dispersant contains 0.5 to 50% by weight of carboxylic acid in one molecule. The conductive paste according to claim 1 or 2, wherein the nonionic polymer binder contains 0.5 to 50% by weight of a glycidyl group and / or a hydroxyl group in one molecule.

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