KR101774069B1 - Electrically conductive paste and metal thin film - Google Patents

Abstract

The present invention relates to a conductive paste containing metal fine particles, branched polyesters and organic solvents, wherein the average particle diameter of the metal fine particles is 1 × 10 ^-3 μm or more and 5 × 10 ^-1 μm or less, Wherein the acid value of the branched polyester is 30 equivalents / 10 ⁶ g or more and 200 equivalents / 10 ⁶ g or less, and the acid value of the branched polyether At least one of the hydrogen atoms bonded to the carbon atoms of the straight chain alkyl diol having 3 to 5 carbon atoms is substituted with a linear chain having 1 to 4 carbon atoms and at least one of the isophthalic acid residue, the orthophthalic acid residue and the cyclohexane dicarboxylic acid residue, Wherein the branched polyester has a glass transition temperature of less than 40 占 폚, and the branched polyesters have a glass transition temperature To 600 to 1,500 parts by weight of the metal fine particles.

Description

ELECTRICALLY CONDUCTIVE PASTE AND METAL THIN FILM BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present invention relates to a conductive paste using a specific polyester resin as a resin binder, a method for producing a metal thin film laminate using the conductive paste, a metal thin film and its application.

A technique of forming a conductive circuit by drawing a circuit using a screen printing or a dispenser with a conductive paste in which conductive fine particles such as metal fine particles are dispersed in a medium is commonly used. The conductive fine particles to be used here are generally flake-shaped particles having a particle diameter of several 占 퐉 or more, and the circuit has a thickness of 10 占 퐉 or more to ensure conductivity. Recently, the density of the conductive circuit has been rapidly increasing. In order to enable formation of a more dense circuit, finer metal fine particles have been developed.

The production method of fine particles is classified into a solid phase method, a vapor phase method, and a liquid phase method depending on the phase to be produced. In the process by pulverization of the solid phase method, the particle diameter is limited to about 0.1 mu m. In the production of particles called nanoparticles having a particle size of several tens of nm or less, the vapor-phase process and the liquid phase process, which are build-up processes, are suitable. Examples of the vapor phase method include a physical condensation method by cooling the high temperature vapor and a particle generation method by a vapor phase chemical reaction.

On the other hand, in the liquid phase method, not only the constituent components of the particles are singly used but also the constituent components of the particles can be adapted to the multi-component system, the process can be diversified, the control of the particle diameter is relatively easy, And various methods are being studied. As the liquid phase method, a coprecipitation method, a sol-gel method, a gel-sol method, an inverted micelle method, a hot-saw method, a spray pyrolysis method and the like have been proposed. The metal fine particles are also synthesized in a colloidal state by a method in which a metal salt is reduced in a solution in the presence of a protective polymer. For example, Patent Document 1 discloses a metal fine particle dispersion containing a linear aliphatic polyether. Patent Document 2 discloses a metal ultrafine particle dispersion stabilized by a polymer having a pyrrolidone group.

It is known that by reducing the particle diameter of the metal fine particles, the firing temperature between the metal fine particles can be drastically lowered. For example, Patent Document 3 discloses a method of forming a metal thin film using a dispersion in which fine metal particles having a particle diameter of 100 nm or less are dispersed. An electric circuit or wiring can be formed by this method. However, the fine particles represented by nanoparticles are very likely to aggregate because of their very large surface area. Therefore, the binder resin and the dispersing agent should be adsorbed on the fine metal particles to prevent coagulation of the fine particles, and to stabilize the dispersion to secure the fluidity of the dispersion. As the fine metal particles become finer in order to stabilize the dispersion, a large amount of binder resin or dispersant is required. Therefore, even when a dispersion containing fine metal particles which can be originally baked at low temperature is used, the binder resin or the dispersant deteriorates the conductivity. An operation of removing the binder resin or the dispersant by sublimation, decomposition and evaporation is required. Further, the adhesion to the substrate such as a film or glass tends to be deteriorated by firing.

It is considered to be advantageous to use a dispersion containing a nonvolatile resin binder in order to exhibit the adhesion between the metal thin film layer and the substrate even after the firing step. On the other hand, the resin binder remains in the coating film It is difficult to obtain a metal thin film layer having a low volume resistivity in practice. For this reason, there are very few such as Patent Document 4 and Patent Document 5 that a highly conductive metal thin film can be obtained by using a resin binder in the dispersion of metal nanoparticles. In Patent Document 4, unspecified resins are said to be usable. However, only the resol-type phenol resin of one specific brand is shown in the examples. Patent Document 5 discloses the use of a polyester resin having a branching unit and a hydroxyl group in a molecule, but it has not yet been possible to achieve sufficient performance in terms of adhesion to a substrate and volume resistivity.

Patent Document 1: Japanese Patent Application Laid-Open No. 2006-9120 Patent Document 2: JP-A-5-224006 Patent Document 3: Japanese Patent No. 2561537 Patent Document 4: Japanese Patent No. 4155821 Specification Patent Document 5: JP-A-2009-62523

A technique of forming a metal thin film laminate by using a conductive paste or a conductive ink and thereby forming a conductive circuit is widely used. As one of measures for achieving high density of the conductive circuit, the circuit width and the circuit thickness are reduced. In order to realize such a change while ensuring conductivity, the metal filler used also has been made into fine particles. On the other hand, in order to ensure workability in forming a conductive circuit, it is necessary to prevent agglomeration of the fine metal particle dispersion to maintain proper viscosity. In order to stabilize the dispersed fine metal particles, . However, the adsorbed organic material deteriorates the conductivity after film formation. In general, the stability in a dispersion body and the conductivity after film formation are opposite.

Disclosure of the Invention Problems to be Solved by the Invention It is an object of the present invention to provide a conductive paste which has both a dispersion stability of a conductive paste and a low volume resistivity (high electric conductivity, low electrical resistance) of a metal thin film layer of a metal thin film laminate formed by using the conductive paste, Paste. The metal thin film in the present invention is not limited to a thin film containing only a metal but may be a thin film containing a metal and other materials such as a branched polyester (B), an organic solvent (C), a curing agent (D) E), and a mixture of at least one material selected from any of the reaction products of these.

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have completed the present invention. That is,

(1) As a conductive paste containing metal fine particles (A), branched polyesters (B) and organic solvents (C)

And an average particle diameter of the metal fine particles (A) less than 1 × 10 ^-3 ㎛ 5 × 10 ^-1 ㎛,

Wherein the branched polyester (B) has a branching point attributed to a polycarboxylic acid compound having three or more functional groups and / or a polyol compound having three or more functional groups,

The acid value of the branched polyester (B) is 30 equivalents / 10 ⁶ g or more and 200 equivalents / 10 ⁶ g or less,

Wherein the branched polyester (B) is at least one of isophthalic acid residue, orthophthalic acid residue and cyclohexanedicarboxylic acid residue, and at least one of hydrogen atoms bonded to carbon atoms of a straight chain alkyl diol having 3 to 5 carbon atoms A linear alkyl group having 1 to 4 carbon atoms as a copolymerization component,

Wherein the total amount of the polycarboxylic acid compound residue and the total polyol compound residue constituting the branched polyester (B) is 200 mol%, the sum of the isophthalic acid residue, the orthophthalic acid residue and the cyclohexanedicarboxylic acid residue Is 70 mol% or more and the total number of residues of the compound in which at least one hydrogen atom bonded to the carbon atom of the straight chain alkyl diol having 3 to 5 carbon atoms is substituted with a straight chain alkyl group having 1 to 4 carbon atoms is 20 mol%

Wherein the branched polyester (B) has a glass transition temperature of less than 40 캜,

Wherein 600 to 1500 parts by weight of the metal fine particles (A) per 100 parts by weight of the branched polyester (B)

Conductive paste.

(2) When the total amount of the polycarboxylic acid compound residue and the total polyol compound residue constituting the branched polyester (B) is 200 mol%, the sum of the orthophthalic acid residue and the cyclohexanedicarboxylic acid residue is (1), wherein the content of the conductive paste is 20 mol% or more and 50 mol% or less.

(3) The conductive paste according to (1) or (2), wherein the content of the metal fine particles (A) is 20 wt% or more and 80 wt% or less of the entire conductive paste.

(4) A conductive paste according to any one of (1) to (3), further containing a curing agent (D).

(5) a step of performing at least one treatment selected from a heating treatment, a calendering treatment and a baking treatment on a coating film formed by applying the conductive paste according to any one of (1) to (4) Wherein the metal thin film laminate is a metal thin film.

(6) The method for producing a metal thin film laminate according to (5), wherein the substrate is an insulating film.

(7) A metal thin film laminate produced by the method of (5) or (6).

(8) An apparatus comprising as an element electric wiring using the thin metal film laminate according to (7).

The conductive paste of the present invention is excellent in dispersion stability and can be applied to a substrate and subjected to a heat drying treatment to form a metal thin film laminate having a metal thin film layer having a low volume resistivity. In the preferred embodiment of the present invention, a metal thin film layer having a higher conductivity can be obtained by calendering and / or baking treatment. In the present preferred embodiment of the invention it is possible to obtain a metal thin film layer of a volume resistivity of 1 × 10 ^-1 Ω cm or less and, more preferred embodiment the 1 × 10 ^-3 Ω cm or less and, still more preferred embodiment 1 × 10 ^- A metal thin film layer exhibiting a volume resistivity of ⁴占 ㆍ m or less, and in a most preferred embodiment, a volume resistivity of 1 占^10-5 ? Cm or less can be obtained. Further, by forming the metal thin film layer with the conductive paste of the present invention, devices such as a metal thin film laminate, an electromagnetic wave shielding metal thin film, a conductive layer for plating, a metal wiring, and a conductive circuit can be formed.

The electroconductive paste of the present invention, mainly as a conductive paste containing the metal fine particles (A), branched polyester (B) and an organic solvent (C), an average particle diameter of the metal fine particles (A) 1 × 10 ^-3 ㎛ and less than 5 × 10 ^-1 ㎛, the branched polyester (B) has a branch point is due to the three or more functional polycarboxylic acid compounds and / or 3 or more functional polyol compound, the branched polyester (B) Contains a carboxyl group in a specific concentration range in the molecule and the total amount of the polycarboxylic acid compound residue and the total polyol compound residue constituting the branched polyester (B) is 200 mol%, the isophthalic acid residue and At least one hydrogen atom bonded to the carbon atom of the straight chain alkyl diol having 3 to 5 carbon atoms is substituted with a straight chain alkyl group having 1 to 4 carbon atoms, the total amount of the orthophthalic acid residue and the cyclohexane dicarboxylic acid residue being 70 mol% (B) has a glass transition temperature of less than 40 占 폚, and the amount of the metal fine particles (B) is 100 parts by weight based on 100 parts by weight of the branched polyester (B) A) of 600 to 1,500 parts by weight.

The average particle size of the metal fine particles (A) used in the present invention is determined by observing metal fine particles randomly selected by field emission scanning electron microscopy and selecting 20 particles closest to the center of each field of view, The diameter of the metal fine particles is measured and the average value is obtained. In the measurement of the diameters of the respective metal fine particles, when the observation shape is not circular, the average value of the longest length and the shortest length is taken as the diameter of the particles.

The upper limit of the average particle diameter of the metal fine particles (A) used in the present invention is 5 10 ^-1 탆 or less, preferably 2.5 10 ^-1 탆 or less, more preferably 1 10 ^-1 탆 or less, ^Lt ; ² > If the average particle diameter of the metal fine particles is too large, the metal fine particles tend to precipitate, adversely affecting the dispersion stability of the conductive paste, and in the case of forming fine lines with the conductive paste, fine line reproducibility may be deteriorated.

The lower limit of the average particle diameter of the metal fine particles (A) is not particularly limited, but is preferably 5 10 ^-3 탆 or more, more preferably 1 10 ^-2 탆 or more, further preferably 4 10 ^-2 to be. If the average particle diameter of the metal fine particles is too small, dispersion of the metal fine particles becomes difficult, and in order to maintain a stable dispersion state, a large amount of a resin binder or other dispersant is required, which makes it difficult to obtain a metal thin film with high conductivity . The fine metal particles used in the present invention may be mixed with different particle diameters so long as the average particle diameter is 5 x 10 < ^-1 >

As the fine metal particles (A) used in the present invention, fine particles may be fused by heat treatment or may be fused, but fused more preferably. Examples of the metal include copper, nickel, cobalt, silver, platinum, gold, molybdenum, and titanium, and silver and copper are particularly preferable. These metal fine particles may be commercially available products or may be prepared by a known method. It is also possible to adopt a structure in which different kinds of metals are stacked, or an organic material or an inorganic material with metal plating.

The shape of the metal fine particles (A) used in the present invention is not particularly limited. A spherical shape, a flat shape, a shape of a tree topographical shape, a rod shape, etc., or a structure in which any one or a plurality of these are mixed or agglomerated.

The content of the metal fine particles (A) in the present invention is preferably 20 to 80% by weight, more preferably 35 to 55% by weight, and still more preferably 35 to 45% by weight of the conductive paste. If the content of the metal fine particles (A) in the conductive paste is too low, it becomes difficult to obtain the thickness of the metal thin film layer by one coating drying. Further, since the viscosity of the conductive paste is lowered, blurring easily occurs in the coating film. The weight ratio of the resin binder (B) to the metal fine particles (A) influences the dispersion stability of the conductive paste, the adhesion of the coating film to the substrate, and the conductivity of the coating film. The weight ratio of the metal fine particles (A) to the resin binder (B) is preferably 600 to 1,500 parts by weight, particularly preferably 800 to 1,200 parts by weight, based on 100 parts by weight of the resin binder (B). By using the resin binder (B), the coagulation of the fine metal particles (A) can be prevented even by using a small amount of such that the conductivity of the coated film is not impaired, and the dispersion stability of the conductive paste and the adhesion of the coating film and the substrate are also excellent.

The branched polyester (B) of the present invention contains at least one of an isophthalic acid residue, an orthophthalic acid residue and a cyclohexanedicarboxylic acid residue as a copolymerization component. More preferably, the cyclohexane dicarboxylic acid residue is a cyclohexane-1,2-dicarboxylic acid residue. By containing these dibasic acid compounds as a copolymerization component, the solvent solubility of the branched polyester resin (B) is improved and the dispersibility and dispersion stability of the metal fine particles (A) are effectively improved.

When the total amount of the polycarboxylic acid compound residue and the total polyol compound residue constituting the branched polyester (B) of the present invention is 200 mol%, the isophthalic acid (B) constituting the branched polyester (B) The sum of the residues, the orthophthalic acid residues and the cyclohexanedicarboxylic acid residues is 70 mol% or more. It is more preferable that the total amount of the orthophthalic acid residue and the cyclohexane dicarboxylic acid residue is 20 mol% or more and 50 mol% or less. By copolymerizing the dibasic acid compound at such a ratio, the solvent solubility of the obtained branched polyester resin (B) is further improved, and the effect that the dispersibility and dispersion stability of the metal fine particles (A) are more effectively improved is exhibited. Examples of the polycarboxylic acid compound residue other than the isophthalic acid residue, the orthophthalic acid residue and the cyclohexanedicarboxylic acid residue constituting the branched polyester (B) of the present invention include aromatic dicarboxylic acids such as terephthalic acid and naphthalenedicarboxylic acid Aliphatic dicarboxylic acid residues such as aliphatic dicarboxylic acids such as aliphatic dicarboxylic acid, dicarboxylic acid, dicarboxylic acid, dicarboxylic acid, and the like can be used.

The branched polyester (B) contains, as a copolymerization component, a compound obtained by substituting at least one hydrogen atom bonded to a carbon atom of a straight chain alkyldiol having 3 to 5 carbon atoms with a straight chain alkyl group having 1 to 4 carbon atoms. By containing these diol compounds as copolymer components, the solvent solubility of the branched polyester resin (B) is improved and the dispersibility and dispersion stability of the metal fine particles (A) are effectively improved.

When the total amount of the polycarboxylic acid compound residue and the total polyol compound residue constituting the branched polyester (B) is set at 200 mol%, the branched polyesters (B) constituting the branched polyester (B) The total of the residues of the compound in which at least one of the hydrogen atoms bonded to the carbon atoms of the straight chain alkyldiols of 5 to 5 is replaced by the straight chain alkyl group of 1 to 4 carbon atoms is at least 20 mol%. By copolymerizing these diol compounds, The solvent solubility of the metal fine particles (B) is further improved and the dispersibility and dispersion stability of the metal fine particles (A) are effectively improved. Specific examples of the compound in which at least one hydrogen atom bonded to the carbon atom of the straight chain alkyl diol having 3 to 5 carbon atoms is substituted with a straight chain alkyl group having 1 to 4 carbon atoms include 2-methyl-1,3-propanediol, 1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 3-methyl- , 4-diethyl-1,5-pentanediol and the like, especially 2-methyl-1,3-propanediol, 2,2-dimethyl- -Propanediol is preferably a residue of a compound in which hydrogen bonded to the carbon at the 2-position of 1,3-propanediol is substituted with a linear alkyl group having 1 to 4 carbon atoms. Examples of the polyol compound residue other than the compound in which at least one hydrogen atom bonded to the carbon atom of the straight chain alkyl diol having 3 to 5 carbon atoms is substituted with a straight chain alkyl group having 1 to 4 carbon atoms include straight chain alkylene groups such as ethylene glycol and 1,3- Aliphatic glycols can be used.

The branched polyester (B) of the present invention has a branching point attributed to a polycarboxylic acid compound having three or more functional groups and / or a polyol compound having three or more functional groups. The polycarboxylic acid having three or more functionalities is preferably an aromatic polycarboxylic acid, and specific examples thereof include compounds having three or more carboxyl groups in one molecule such as trimellitic acid, trimesic acid, pyromellitic acid, etc., It is also possible to use species together. On the other hand, as the polyol compound having three or more functional groups, an aliphatic polyol is preferable, and a compound having three or more hydroxyl groups in one molecule such as glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, etc., It is possible. It is also possible to use a polycarboxylic acid having three or more functions and a polyol compound having three or more functions in combination.

Wherein the total amount of the polycarboxylic acid compound residue and the total polyol compound residue constituting the branched polyester (B) is 200 mol%, the sum of the trifunctional polycarboxylic acid compound and the trifunctional or more polyol compound The copolymerization ratio is preferably from 0.1 mol% to 10 mol%, more preferably from 0.3 to 5 mol%, and still more preferably from 1 to 3 mol%. If the copolymerization ratio of the branching component is too low, the number of the molecular end of the branched polyester (B) to be obtained becomes small, and a polar group having a sufficient amount can not be introduced into the molecular end. If the copolymerization ratio is excessively high, There is a high possibility of causing gelation in the course of production, which tends to cause problems in production stability.

The branched polyester (B) of the present invention has an acid value of 30 equivalents / 10 ⁶ g or more and 200 equivalents / 10 ⁶ g or less, more preferably 40 equivalents / 10 ⁶ g or more and 180 equivalents / 10 ⁶ g or less. As a method of imparting an acid value to the branched polyester (B), there can be mentioned a method of polymerizing branched polyesters obtained by copolymerizing the trifunctional or higher polycarboxylic acid and polyol compound with various polycarboxylic acid anhydrides in an inert gas atmosphere Can be obtained by ring opening addition at the molecular end mainly by mixing. Specific examples of the polycarboxylic acid anhydride include trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic acid anhydride, 3,3 ', 4,4'-bis (benzoyloxy) ethylene tetracarboxylic acid anhydride, And anhydride. Of these, trimellitic anhydride is most preferable from the viewpoint of reactivity. The carboxyl groups introduced into these molecules have the effect of effectively adsorbing the branched polyester molecules to the surface of the metal fine particles to improve the dispersibility and dispersion stability of the metal fine particles in a paste state.

The branched polyester (B) of the present invention has a glass transition temperature of less than 40 캜. When the temperature is 40 占 폚 or more, there is a problem that it is difficult to obtain the interfacial adhesion between the surface of the substrate such as polyimide film and the fine particle metal dispersion layer obtained by applying and drying the fine metal particle paste. The method of setting the glass transition temperature of the branched polyester (B) to less than 40 占 폚 includes, for example, an isophthalic acid residue constituting the acid component of the branched polyester (B), an orthophthalic acid residue, A method of copolymerizing an aliphatic dibasic acid compound having 4 or more carbon atoms in a range of less than 30 mol% as a polycarboxylic acid compound other than a carboxylic acid residue and a method of copolymerizing an aliphatic diol compound having 5 or more carbon atoms as a diol component . Examples of the aliphatic dibasic acid compound having 4 or more carbon atoms include adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, dimeric acid and the like. Examples of the aliphatic diol compound having 5 or more carbon atoms include 1,5-pentanediol, 1,6-hexanediol, 2,2-diethyl-1,3-propanediol, -Propanediol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol and the like.

The number average molecular weight of the branched polyester (B) of the present invention is preferably from 4,000 to 100,000, particularly preferably from 8,000 to 50,000, from the viewpoints of dispersibility of the fine metal particles and adhesion to a substrate.

The organic solvent (C) used in the conductive paste of the present invention is selected from those which dissolve the branched polyesters (B). The organic solvent (C) has a role of adjusting the viscosity and fluidity of the conductive paste in addition to the role of dispersing the metal fine particles (A) in the conductive paste. Examples of the organic solvent (C) include alcohols, ethers, ketones, esters, aromatic hydrocarbons, and amides. Preferable examples include ethyl carbitol acetate, butyl cellosolve acetate, methyl ethyl ketone, cyclohexanone, n-butyl alcohol, sec-butyl alcohol and tert-butyl alcohol.

The conductive paste of the present invention may optionally contain a curing agent (D). Examples of the curing agent (D) usable in the present invention include a phenol resin, an amino resin, an isocyanate compound, and an epoxy resin. The amount of the curing agent used is preferably in the range of 1 to 30% by weight of the branched polyester (B). By mixing the curing agent (D), the effect of further improving the adhesion of the interface between the substrate and the conductive layer formed of the conductive paste of the present invention may be exerted.

The conductive paste of the present invention contains branching polyester (B) having a dispersing function as an essential component in the fine metal particles (A), but other dispersing agents may be further blended. Examples of the dispersing agent include higher fatty acids such as stearic acid, oleic acid and myristic acid, fatty acid amides, fatty acid metal salts, phosphoric acid esters and sulfonic acid esters. The amount of the dispersing agent used is preferably in the range of 0.1 to 10% by weight of the branched polyester (B).

As a method of producing the conductive paste of the present invention, a general method of dispersing the powder in a liquid can be used. For example, a mixture containing a solution of the metal fine particles (A) and the branched polyester (B) and, if necessary, a further solvent is mixed and dispersed by an ultrasonic method, a mixer method, a three roll method, a ball mill method do. It is also possible to disperse a plurality of these dispersion means in combination. Such dispersion treatment may be performed at room temperature or by heating.

In order to form the metal thin film layer on the substrate using the conductive paste of the present invention, a general method used when the liquid dispersion is applied to the substrate can be used. For example, a screen printing method, a dip coating method, a spray coating method, a spin coating method, an ink jet method, a convex printing method, a concave printing method and the like. The metal thin film layer can be formed by evaporating at least a part of the solvent from the coating film formed by printing or coating by heating, depressurization, air blowing, or a combination thereof, or by natural drying.

Depending on the method of forming the metal thin film layer, the viscosity of the conductive paste may have a great influence on the workability of coating and the performance of the resulting metal thin film layer. In general, when the mixing ratio of the organic solvent is increased to lower the viscosity of the conductive paste, the precipitation of the metal fine particles tends to occur. However, inclusion of the branched polyester (B) in the dispersion medium suppresses sedimentation of the metal fine particles even at a low viscosity. There is a tendency to be able to do.

After forming the metal thin film layer, it is preferable to carry out the calendering (pressurizing treatment) within a range in which the metal thin film layer is not broken. The conductivity of the metal thin film layer tends to be improved by calendering. Calendering is generally performed by applying a linear pressure between a metal roll and an elastic roll depending on the material, for example, a pressure of 1 to 100 kg / cm. It is particularly preferable that the calendering is performed by heating at a temperature not lower than the glass transition temperature of the branched polyester (B). The calendering may be performed in a state where another layer is laminated on the metal thin film layer.

It is preferable that the conductive metal thin film layer obtained in the present invention is further subjected to a sintering treatment. The firing treatment tends to exert a particularly high effect when the particle size of the metal fine particles is 100 nm or less. Although the crystallinity of the metal fine particles varies depending on the surface state such as the degree of oxidation and the degree of oxidation, fusion starts at a temperature much lower than the melting point of the bulk, which is large in the so-called nanoparticles. In the present invention, the firing treatment refers to a heat treatment in which fusion of at least a part of the metal fine particles (A) occurs, and it is not necessary to decompose or volatilize the branched polyester (B).

Example

The following examples are provided to further illustrate the present invention, but the present invention is not limited to the examples at all. Further, the measurements described in the examples were measured by the following methods. Unless otherwise stated, parts denote parts by weight.

Hereinafter, the abbreviations of the compounds shown in the main text and the tables in the examples represent the following compounds, respectively.

T: Terephthalic acid

I: isophthalic acid

O: orthophthalic acid

SIPA: Sodium 5-sulfoisophthalate

HOPA: hydrogenated orthophthalic acid

AA: adipic acid

SA: sebacinic acid

TMA: Anhydrous trimellitic acid

NPG: neopentyl glycol

EG: ethylene glycol

PD: 1,5-pentanediol

HD: 1,6-hexanediol

2MD: 2-methyl-1,3-propanediol

BEPD: 2-butyl-2-ethyl-1,3-propanediol

DEG: diethylene glycol

Resin composition: The sample was dissolved in deuterated chloroform and quantified by ¹ H-NMR using a 400 MHz nuclear magnetic resonance (NMR) spectrometer (manufactured by Varian). The measurement conditions are room temperature, d1 = 26s.

Number average molecular weight: The sample was dissolved in tetrahydrofuran so that the resin concentration was about 0.5% by weight and filtered through a membrane filter made of polysulfide ethylene, having a pore diameter of 0.5 탆, as a sample for measurement. Tetrahydrofuran was used as a mobile phase And the number average molecular weight was measured by gel permeation chromatography using a differential refractometer as a detector. The flow rate was 1 mL / min, and the column temperature was 30 占 폚. Columns KF-802, 804L and 806L manufactured by Showa Denko KK were used. Monodispersed polystyrene was used for the molecular weight standard.

Specific Gravity: About 0.1 g of a sample was put into an aqueous solution of calcium chloride at a water temperature of 30 占 폚 and the specific gravity of the aqueous solution of calcium chloride was measured with a specific gravity meter when the calcium chloride concentration was adjusted so that the resin did not settle.

Acid value: 0.2 g of the resin was dissolved in 20 ml of tetrahydrofuran, and the solution was measured with phenolphthalein as an indicator in 0.1 N-NaOH ethanol solution. The measurements are expressed in equivalents in 10 ⁶ g resin solids.

Glass transition temperature: 5 mg of the sample was placed in a sample pan made of aluminum, sealed, and measured at a heating rate of 20 캜 / minute to 200 캜 using a differential scanning calorimeter DSC-220 manufactured by Seiko Instruments Inc., At the intersection of the extension line of the baseline and the tangent line indicating the maximum inclination at the transition portion.

Conductivity: Measured using a DC bridge precision bridge measuring 2769-10 manufactured by Yokogawa M & C Co., Ltd. The conductivity is represented by a volume resistivity (unit: Ω · cm).

Dispersion stability: After the conductive paste was allowed to stand at 30 占 폚 for 24 hours, the presence or absence of the precipitate was observed.

○ --- No precipitation.

? --- A little precipitation is seen, and the amount of precipitation is 20% by weight or less of all the metal fine particles.

× --- There is a large amount of sediment. The sedimentation amount exceeds 20% by weight of the total metal fine particles.

Substrate adhesion: The adhesion of the metal thin film layer to the substrate was evaluated by a tape peel test at room temperature. In the peeling test, a scotch tape manufactured by Sumitomo 3M Ltd. was attached, and the peeling state of the metal thin film layer was observed.

○ --- No peeling

△ --- Partially peeled off.

× --- Front peeled off.

Metal fine particles used

Silver fine particles (1):

Reduction of silver nitrate in ascorbic acid and dodecylamine in hexane was achieved. After washing and drying, the particles were observed with a transmission electron microscope and found to be spherical particles having an average particle diameter of 60 nm.

Silver fine particles (2):

Silver nitrate was obtained by reduction with sodium borohydride and dodecylamine in hexane. After washing and drying, the particles were spherical particles having an average particle diameter of 830 nm as observed by a transmission electron microscope.

Silver fine particles (3):

Reduction of silver nitrate with ascorbic acid and octylamine in hexane was obtained. After washing and drying, the particles were spherical particles having an average particle diameter of 143 nm as observed by a transmission electron microscope.

Synthetic example  1 carboxyl group-containing branched polyester ( b1 ) Synthesis of

131.9 parts of dimethyl isophthalate, 48.0 parts of neopentyl glycol, 122.0 parts of 1,6-hexanediol, and 0.1 part of tetrabutoxy titanate were placed in a reaction vessel equipped with a stirrer, a thermometer, a stirrer and a Liebig condenser tube and heated at 150 to 230 DEG C for 180 minutes After the ester exchange by heating, 43.7 parts of phthalic anhydride and 3.8 parts of trimellitic anhydride were added, and the esterification reaction was carried out at 200 to 250 ° C for 60 minutes. Subsequently, while the temperature was raised to 260 ° C, the system was gradually decompressed to make it 0.3 mmHg or less after 10 minutes. After 60 minutes of reaction under this condition, the reaction system was returned to atmospheric pressure under a nitrogen atmosphere, and the temperature of the system was set at 220 占 폚. 1.9 parts of trimellitic anhydride was added and stirred at 220 캜 for 45 minutes under atmospheric nitrogen atmosphere to obtain a light yellow transparent polyester (b1). The results of the analysis of the obtained resin are shown in Tables 1 and 2.

Synthetic example  2 carboxyl group-containing branched polyester ( b2 ) Synthesis of

131.9 parts of dimethyl isophthalate, 48.0 parts of neopentyl glycol, 122.0 parts of 1,6-hexanediol, and 0.1 part of tetrabutoxy titanate were placed in a reaction vessel equipped with a stirrer, a thermometer, a stirrer and a Liebig condenser tube and heated at 150 to 230 DEG C for 180 minutes After the ester exchange by heating, 42.9 parts of phthalic anhydride and 3.8 parts of trimellitic anhydride were added, and the esterification reaction was carried out at 200 to 250 캜 for 60 minutes. Subsequently, while the temperature was raised to 260 ° C, the system was gradually decompressed to make it 0.3 mmHg or less after 10 minutes. After 60 minutes of reaction under this condition, the reaction system was returned to atmospheric pressure under a nitrogen atmosphere, and the temperature of the system was set at 220 占 폚. And 3.8 parts of trimellitic anhydride was added and stirred at 220 캜 for 45 minutes under atmospheric nitrogen atmosphere to obtain a pale yellow transparent polyester (b2). The results of the analysis of the obtained resin are shown in Tables 1 and 2.

Synthetic example  3 carboxyl group-containing branched polyester ( b3 ) Synthesis of

131.9 parts of dimethyl isophthalate, 48.0 parts of neopentyl glycol, 122.0 parts of 1,6-hexanediol, and 0.1 part of tetrabutoxy titanate were placed in a reaction vessel equipped with a stirrer, a thermometer, a stirrer and a Liebig condenser tube and heated at 150 to 230 DEG C for 180 minutes After the ester exchange by heating, 44.1 parts of phthalic anhydride and 3.8 parts of trimellitic anhydride were added, and the esterification reaction was carried out at 200 to 250 ° C for 60 minutes. Subsequently, while the temperature was raised to 260 ° C, the system was gradually decompressed to make it 0.3 mmHg or less after 10 minutes. After 60 minutes of reaction under this condition, the reaction system was returned to atmospheric pressure under a nitrogen atmosphere, and the temperature of the system was set at 220 占 폚. 1 part of trimellitic anhydride was added, and the mixture was stirred at 220 캜 for 45 minutes under atmospheric nitrogen atmosphere to obtain a light yellow transparent polyester (b3). The results of the analysis of the obtained resin are shown in Tables 1 and 2.

Synthetic example  4 carboxyl group-containing branched polyester ( b4 ) Synthesis of

97.0 parts of dimethyl isophthalate, 153.0 parts of 2-methyl-1,3-propanediol, 48.0 parts of 2-butyl-2-ethyl-1,3-propanediol, and 0.10 part of tetrabutoxide were added to a reaction vessel equipped with a stirrer, Cittanate was added and the mixture was heated at 150 to 230 占 폚 for 180 minutes to effect transesterification. Then, 45.4 parts of hydrogenated phthalic anhydride, 26.3 parts of adipic acid and 3.8 parts of anhydrous trimellitic acid were added to carry out the esterification reaction at 200 to 250 Lt; 0 > C for 60 minutes. Subsequently, while the temperature was raised to 260 ° C, the system was gradually decompressed to make it 0.3 mmHg or less after 10 minutes. After 60 minutes of reaction under this condition, the reaction system was returned to atmospheric pressure under a nitrogen atmosphere, and the temperature of the system was set at 220 占 폚. 1.9 parts of trimellitic anhydride was added and stirred at 220 캜 for 45 minutes under atmospheric nitrogen atmosphere to obtain a light yellow transparent polyester (b4). The results of the analysis of the obtained resin are shown in Tables 1 and 2.

Synthetic example  5 carboxyl group-containing branched polyester ( b5 ) Synthesis of

In a reaction vessel equipped with a thermometer, a stirrer and a Libyhich tube, 131.9 parts of dimethyl isophthalate, 99.0 parts of 2-methyl-1,3-propanediol, 94.0 parts of 1,5-pentanediol and 0.1 part of tetrabutoxy titanate, After the transesterification by heating at 150 to 230 캜 for 180 minutes, 45.4 parts of hydrogenated phthalic anhydride and 3.8 parts of anhydrous trimellitic acid were added to carry out the esterification reaction at 200 to 250 캜 for 60 minutes. Subsequently, while the temperature was raised to 260 ° C, the system was gradually decompressed to make it 0.3 mmHg or less after 10 minutes. After 60 minutes of reaction under this condition, the reaction system was returned to atmospheric pressure under a nitrogen atmosphere, and the temperature of the system was set at 220 占 폚. 1.9 parts of trimellitic anhydride was added and stirred at 220 캜 for 45 minutes under atmospheric pressure nitrogen atmosphere to obtain a light yellow transparent polyester (b5). The results of the analysis of the obtained resin are shown in Tables 1 and 2.

compare Synthetic example  6 branched polyester without addition of carboxyl group ( b6 ) Synthesis of

131.9 parts of dimethyl isophthalate, 48.0 parts of neopentyl glycol, 122.0 parts of 1,6-hexanediol, and 0.1 part of tetrabutoxy titanate were placed in a reaction vessel equipped with a stirrer, a thermometer, a stirrer and a Liebig condenser tube and heated at 150 to 230 DEG C for 180 minutes After the ester exchange by heating, 44.4 parts of phthalic anhydride and 3.8 parts of trimellitic anhydride were added and the esterification reaction was carried out at 200 to 250 캜 for 60 minutes. Subsequently, while the temperature was raised to 260 ° C, the system was gradually decompressed to make it 0.3 mmHg or less after 10 minutes. After 60 minutes of reaction under these conditions, the reaction was terminated without adding trimellitic anhydride to obtain a light yellow transparent polyester (b6). The results of the analysis of the obtained resin are shown in Tables 1 and 2.

compare Synthetic example  7 Carboxyl group-containing branched polyester ( b7 ) Synthesis of

95.1 parts of dimethyl terephthalate, 94.1 parts of dimethyl isophthalate, 3.8 parts of anhydrous trimellitic acid, 73.0 parts of 2,2-dimethyl-1,3-propanediol, and 81.0 parts of ethylene glycol were added to a reaction vessel equipped with a thermometer, a stirrer, And 0.1 part of tetrabutoxy titanate were charged and ester exchanged by heating at 150 to 230 캜 for 180 minutes. Thereafter, the reaction system was heated to 250 캜 for 30 minutes. Subsequently, the system was gradually decompressed while being heated to 260 캜, mmHg or less. After 60 minutes of reaction under this condition, the reaction system was returned to atmospheric pressure under a nitrogen atmosphere, and the temperature of the system was set at 220 占 폚. 1.9 parts of trimellitic anhydride was added and stirred at 220 캜 for 45 minutes under atmospheric nitrogen atmosphere to obtain a light yellow transparent polyester (b7). The results of the analysis of the obtained resin are shown in Tables 1 and 2.

compare Synthetic example  8 carboxyl group-containing polyester ( b8 ) Synthesis of

135.8 parts of dimethyl isophthalate, 48.0 parts of neopentyl glycol, 122.0 parts of 1,6-hexanediol, and 0.1 part of tetrabutoxy titanate were placed in a reaction vessel equipped with a stirrer, a thermometer, a stirrer and a Liebig condenser tube and heated at 150 to 230 DEG C for 180 minutes After the ester exchange by heating, 43.7 parts of phthalic anhydride was added, and the esterification reaction was carried out at 200 to 250 캜 for 60 minutes. Subsequently, while the temperature was raised to 260 ° C, the system was gradually decompressed to make it 0.3 mmHg or less after 10 minutes. After 60 minutes of reaction under this condition, the reaction system was returned to atmospheric pressure under a nitrogen atmosphere, and the temperature of the system was set at 220 占 폚. 1.9 parts of trimellitic anhydride was added and the mixture was stirred at 220 캜 for 45 minutes under atmospheric nitrogen atmosphere to obtain a light yellow transparent polyester (b8). The results of the analysis of the obtained resin are shown in Tables 1 and 2.

compare Synthetic example  9 Carboxyl group-containing branched polyester ( b9 ) Synthesis of

92.2 parts of dimethyl terephthalate, 97.0 parts of dimethyl isophthalate, 3.8 parts of anhydrous trimellitic acid, 99.2 parts of ethylene glycol, 42.4 parts of diethylene glycol, and 0.1 part of tetrabutoxy titanate were placed in a reaction vessel equipped with a thermometer, a stirrer and a Liebig condenser tube After the ester exchange was carried out at 150 to 230 캜 for 180 minutes, the reaction system was heated to 250 캜 for 30 minutes. Subsequently, the system was gradually reduced in pressure while being heated to 260 캜 and made to be 0.3 mmHg or less after 10 minutes. After 60 minutes of reaction under this condition, the reaction system was returned to atmospheric pressure under a nitrogen atmosphere, and the temperature of the system was set at 220 占 폚. 1.9 parts of trimellitic anhydride was added, and the mixture was stirred at 220 占 폚 for 45 minutes under atmospheric nitrogen atmosphere to obtain a light yellow transparent polyester (b9). The results of the analysis of the obtained resin are shown in Tables 1 and 2.

compare Synthetic example  10 carboxyl group-containing branched polyester ( b10 ) Synthesis of

131.9 parts of dimethyl isophthalate, 48.0 parts of neopentyl glycol, 122.0 parts of 1,6-hexanediol, and 0.1 part of tetrabutoxy titanate were placed in a reaction vessel equipped with a stirrer, a thermometer, a stirrer, and a Liebig condenser tube and heated at 150 to 230 DEG C for 180 minutes After the ester exchange by heating, 42.2 parts of phthalic anhydride and 3.8 parts of trimellitic anhydride were added, and the esterification reaction was carried out at 200 to 250 ° C for 60 minutes. Subsequently, while the temperature was raised to 260 ° C, the system was gradually decompressed to make it 0.3 mmHg or less after 10 minutes. After 60 minutes of reaction under these conditions, the reaction was terminated without adding trimellitic anhydride to obtain a light yellow transparent polyester (b10). The results of the analysis of the obtained resin are shown in Tables 1 and 2.

compare Synthetic example  11 sulfonic acid metal base-containing polyester ( b11 ) Synthesis of

In a reaction vessel equipped with a thermometer, a stirrer and a Libyhich tube, 126.1 parts of dimethyl isophthalate, 14.8 parts of sodium 5-sulfoisophthalate, 48.0 parts of neopentyl glycol, 122.0 parts of 1,6-hexanediol and 0.1 parts of tetrabutoxy titanate And the mixture was heated at 150 to 230 캜 for 180 minutes to effect transesterification. Then, 44.4 parts of phthalic anhydride was added to carry out the esterification reaction at 200 to 250 캜 for 60 minutes. Subsequently, while the temperature was raised to 260 ° C, the system was gradually decompressed to make it 0.3 mmHg or less after 10 minutes. After 60 minutes of reaction under the above conditions, 3.8 parts of trimellitic anhydride was added and stirred at 220 ° C for 45 minutes under atmospheric nitrogen atmosphere to obtain pale yellow transparent polyester (b11). The analysis results of the obtained resin are shown in Tables 1 and 2.

[Table 1]

[Table 2]

Example 1

The composition of the following combination ratio was kneaded with three rolls.

8.3 parts of a solution of polyester (b1)

(24 wt% solution of ethylcarbitol acetate / butyl cellosolve acetate = 1/1 (weight ratio)

Fine silver particles 1 (average particle diameter 60 nm) 23.0 parts

To the resulting kneaded product, 9.3 parts of ethylcarbitol acetate and butyl cellosolve acetate were added, and the mixture was stirred with a planetary mixer for 10 minutes to obtain a conductive paste having a solid concentration of 50% by weight.

The obtained conductive paste was applied on a polyimide film having a thickness of 25 占 퐉 to a thickness of 2 占 퐉 after drying and dried at 120 占 폚 for 10 minutes to obtain a metal thin film layer. Then, it was passed through a calender roll including a chromium plating roll and a rubber roll at 100 占 폚 and a linear pressure of 50 kg / cm. Further, the resultant was heat-treated at 180 DEG C for 1 hour to promote firing of the silver microparticles. Table 3 shows the dispersion stability of the conductive paste, the substrate adhesion of the metal thin film layer and the measurement results of the conductivity. Table 3 shows the conductivity in the case of performing the firing treatment without the calendering treatment.

Examples 2 to 5 and Comparative Examples 6 to 11

A conductive paste having the mixing ratios shown in Tables 3 and 4 was obtained in the same manner as in Example 1. [ The evaluation was carried out in the same manner as in Example 1. The results are shown in Tables 3 and 4.

Comparative Examples 12 and 13

A metal thin film layer was formed in the same manner as in Example 1 except that silver particles (2) were used in place of the silver particles (1) as metal fine particles. The results are shown in Table 4.

Examples 14 and 15

A metal thin film layer was formed in the same manner as in Example 1, except that the silver (3) was used instead of the silver (1) as the metal fine particles. The results are shown in Table 4.

Examples 16 and 17 and Comparative Examples 18 to 20

A conductive thin film was formed in the same manner as in Example 1 except that the silver particles (1) or (3) were used as the metal fine particles and the mixing ratio of the silver fine particles and the branched polyester (b1) The evaluation was carried out in the same manner as in Example 1. The results are shown in Table 4. However, in Comparative Example 19, the kneaded product by the three rolls did not become paste-like and could not be thinly coated on the substrate.

[Table 3]

[Table 4]

As shown in Tables 3 and 4, the dispersion of metal fine particles of the present invention is excellent in dispersion stability of metal particles, and the metal thin film layer formed of the conductive paste of the present invention is excellent in adhesion to a substrate. In addition, it can be seen that excellent conductive performance is exhibited. In Comparative Example 6, in the case where the branched polyester resin as a binder does not have an acid value, in Comparative Example 7, in the case where the acid component of the branched polyester resin deviates from the scope of the present invention and the glass transition temperature also deviates from the scope of the invention, Is a case in which the polyester resin does not have a branched structure. Further, in Comparative Example 9, both the acid component and the glycol component deviate from the scope of the present invention, and the glass transition temperature also deviates from the scope of the claims. In Comparative Example 10, the acid value of the branched polyester resin of the present invention was deviated from the scope of the present invention. In Comparative Example 11, a polyester resin containing a sulfonic acid metal base excellent in dispersion effect of magnetic particles This is an example of the case, but there is no branch structure, and the acid value is outside the scope of the claims. In Comparative Examples 12 and 13, the particle diameters of the metal particles do not satisfy the requirements of the present invention. In Comparative Examples 18 to 20, the mixing ratio of the silver fine particles and the branched polyester resin is outside the scope of the present invention.

The conductive paste of the present invention is excellent in dispersion stability and can be applied on a substrate and subjected to a heat drying treatment to form a thin metal film having excellent adhesion to a substrate and a low volume resistivity. The obtained metal thin film can be used for a metal / resin laminate, an electromagnetic shielding metal thin film, a conductive layer for plating, a metal wiring material, a conductive material and the like.

Claims (8)

As the conductive paste containing the metal fine particles (A), the branched polyesters (B) and the organic solvent (C)
And an average particle diameter of the metal fine particles (A) less than 1 × 10 ^-3 ㎛ 5 × 10 ^-1 ㎛,
Wherein the branched polyester (B) has a branching point attributable to a polycarboxylic acid compound having three or more functional groups or a branching point attributable to a polyol compound having three or more functional groups,
The acid value of the branched polyester (B) is 30 equivalents / 10 ⁶ g or more and 200 equivalents / 10 ⁶ g or less,
Wherein the branched polyester (B) is at least one of isophthalic acid residue, orthophthalic acid residue and cyclohexanedicarboxylic acid residue and at least one hydrogen atom bonded to the carbon atom of a straight chain alkyl diol having 3 to 5 carbon atoms, A linear alkyl group having 1 to 4 carbon atoms as a copolymerization component,
Wherein the total amount of the polycarboxylic acid compound residue and the total polyol compound residue constituting the branched polyester (B) is 200 mol%, the sum of the isophthalic acid residue, the orthophthalic acid residue and the cyclohexanedicarboxylic acid residue Is 70 mol% or more, and the total of the residues of the compound in which at least one of the hydrogen atoms bonded to the carbon atoms of the straight chain alkyl diol having 3 to 5 carbon atoms is substituted with a straight chain alkyl group having 1 to 4 carbon atoms is 20 mol%
Wherein the branched polyester (B) has a glass transition temperature of less than 40 캜,
Wherein 600 to 1500 parts by weight of the metal fine particles (A) per 100 parts by weight of the branched polyester (B)
Conductive paste. The method for producing a branched polyester (B) according to claim 1, wherein, when the total amount of the polycarboxylic acid compound residue and the total polyol compound residue constituting the branched polyester (B) is 200 mol%, the ratio of the orthophthalic acid residue to the cyclohexanedicarboxylic acid residue Is not less than 20 mol% and not more than 50 mol%. The conductive paste according to claim 1 or 2, wherein the content of the metal fine particles (A) is 20 wt% or more and 80 wt% or less of the entire conductive paste. The conductive paste according to claim 1 or 2, further comprising a curing agent (D). A process for producing a metal thin film laminate including a step of performing at least one treatment selected from a heating treatment, a calendering treatment and a firing treatment on a coating film formed by applying the conductive paste according to claim 1 or 2 to a substrate Way. The method for manufacturing a metal thin film laminate according to claim 5, wherein the substrate is an insulating film. A thin metal film laminate produced by the manufacturing method according to claim 5. An apparatus comprising the electric wiring using the metal thin film laminate according to claim 7 as a component.