KR101371863B1 - Conductive paste and conductive pattern - Google Patents

Conductive paste and conductive pattern Download PDF

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KR101371863B1
KR101371863B1 KR20120031500A KR20120031500A KR101371863B1 KR 101371863 B1 KR101371863 B1 KR 101371863B1 KR 20120031500 A KR20120031500 A KR 20120031500A KR 20120031500 A KR20120031500 A KR 20120031500A KR 101371863 B1 KR101371863 B1 KR 101371863B1
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resin
conductive paste
pattern
silver powder
electrically conductive
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KR20120112122A (en
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마사끼 사사끼
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다이요 홀딩스 가부시키가이샤
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Abstract

The present invention provides a conductive paste capable of forming a fine pattern having good printability and capable of obtaining good electrical characteristics without using a high temperature process.
In the conductive paste, a silver powder having a tap density of 4.9 to 6.0 g / cm 3 , a specific surface area of 0.7 to 1.3 m 2 / g, and an average particle diameter of 0.6 to 1.0 μm, a thermosetting resin, a thermoplastic resin, and a heat-drying resin At least 1 sort (s) of organic binder resin and an organic solvent are contained.

Description

Conductive Paste and Conductive Pattern {CONDUCTIVE PASTE AND CONDUCTIVE PATTERN}
The present invention relates to a conductive paste and a conductive pattern used for forming a conductive pattern such as an electrode of an electronic device, for example.
As a method of forming a fine conductive pattern on a substrate using a conductive paste containing a conductive powder and an organic binder resin, printing methods such as gravure printing and gravure offset printing, which are additive processes for adding a material to a desired location, are widely used. have. In such a printing method, in order to transfer ink to a substrate via a plate, good transferability is required. For this reason, the paste which has the appropriate rheological characteristic corresponding to the printing of a fine conductive pattern, and is excellent in printability is calculated | required.
As an application of forming such a fine printing pattern, the electromagnetic wave shielding mesh for a display is mentioned, for example. In order to shield electromagnetic waves generated from display devices such as PDP (plasma display panel), CRT (cathode ray tube), and the like, a functional film having a grid-shaped conductive pattern is disposed on the display front face. For this reason, it is necessary to form a fine pattern in the shielding mesh so that the visibility of a display may not be affected. In addition, the formed pattern impairs shielding performance unless it exhibits good conductivity (low resistance). Moreover, since the base material contains a resin film, the electromagnetic wave shielding mesh also needs to form a conductive pattern by a low temperature process.
Various proposals are made about the conductive paste which can form a conductive pattern at low temperature (for example, refer patent document 1). However, in the formed conductive pattern, it is difficult to obtain practical good electrical characteristics such as a resistance value of 10 −5 Ω · cm order. Therefore, although it is conceivable to use flakes as the conductive powder, there is a problem that it is difficult to obtain a fine print pattern.
Japanese Patent Application Laid-Open No. 2004-355933
As such, it is possible to form a fine conductive pattern without using a high temperature process, and it is required to obtain good electrical characteristics in the pattern to be formed. In addition, when forming the conductive pattern in the electronic device by the printing method, it is necessary to have good printability. However, there is a problem that it is difficult to obtain a paste that satisfies these simultaneously.
An object of the present invention is to provide a conductive paste having good printability and capable of forming a fine conductive pattern capable of obtaining good electrical characteristics without using a high temperature process.
In order to solve this problem, the conductive paste of one embodiment of the present invention has a tap density of 4.9 to 6.0 g / cm 3 , a specific surface area of 0.7 to 1.3 m 2 / g, and an average particle diameter measured by a scanning electron microscope. It is characterized by containing the silver powder of 0.6-1.0 micrometer, at least 1 sort (s) of organic binder resin of a thermosetting resin, a thermoplastic resin, and a thermosetting resin, and an organic solvent.
By this structure, it becomes possible to form the pattern which has favorable printability and can acquire favorable electrical characteristics, without using a high temperature process.
Moreover, in the electrically conductive paste of one aspect of this invention, it is preferable that silver powder is spherical. By spherical shape, dispersibility can be improved.
Moreover, the formation method of the electrically conductive pattern of one aspect of this invention forms a coating film pattern by printing using such an electrically conductive paste, and dries and / or hardens this coating film pattern at 80-200 degreeC. By forming a conductive pattern in this way, application to devices with low heat resistance, such as a flexible device, becomes possible.
Further, the conductive pattern of one embodiment of the present invention has a tap density of 4.9 to 6.0 g / cm 3 , a specific surface area of 0.7 to 1.3 m 2 / g, and an average particle diameter of 0.6 to 1.0 μm as measured by a scanning electron microscope. It is characterized by containing a silver powder and an organic binder resin. This configuration makes it possible to obtain a conductive pattern having good electrical characteristics with high density.
According to the electrically conductive paste of one aspect of this invention, it becomes possible to form the conductive pattern which has favorable printability and can acquire favorable electrical characteristics, without using a high temperature process.
EMBODIMENT OF THE INVENTION Hereinafter, the electrically conductive paste of one Embodiment of this invention is demonstrated.
The conductive paste of the present embodiment has a silver powder having a tap density of 4.9 to 6.0 g / cm 3 , a specific surface area of 0.7 to 1.3 m 2 / g, and an average particle diameter of 0.6 to 1.0 μm measured by a scanning electron microscope, It is characterized by containing an organic binder resin and an organic solvent.
Silver powder in the electrically conductive paste of this embodiment is used in order to provide electroconductivity in the electrically conductive pattern formed.
In such silver powder, the tap density is 4.9 to 6.0 g / cm 3 . When the tap density is less than 4.9 g / cm 3 , since the density of the silver powder of the formed circuit pattern decreases, it is difficult to obtain a low resistance conductive pattern. More preferably, it is 5.2-6.0 g / cm <3> .
In addition, the specific surface area is set to 0.7 to 1.3 m 2 / g. If the specific surface area is less than 0.7 m 2 / g, sedimentation is likely to occur during storage, while if the specific surface area exceeds 1.3 m 2 / g, the oil absorption amount becomes large, and the fluidity of the paste is impaired. More preferably, it is 0.9-1.1 m <2> / g.
In addition, the average particle diameter measured with the scanning electron microscope shall be 0.6-1.0 micrometer. The average particle diameter is obtained by the average particle diameter of ten random silver powders observed at 10,000 times using a scanning electron microscope (SEM). If average particle diameter is less than 0.6 micrometer, contact of silver powder will arise and it will become difficult, and it becomes difficult to acquire sufficient electroconductivity. On the other hand, when the average particle diameter exceeds 1.0 μm, it is difficult to obtain the compactness of the formed conductive pattern.
As the shape thereof, spherical shape, flake shape, dendrite shape and the like can be used in various shapes. In particular, in consideration of printability and dispersibility in the paste, it is preferable to use a spherical shape having an aspect ratio of 1 to 1.5 as a main agent.
It is preferable that the compounding ratio of such a silver powder is 85-97 mass% based on the non volatile matter of the electrically conductive paste (the component which remain | survives in a film | membrane not volatilizing from the paste by drying). If it is less than 85 mass%, it will become difficult to obtain sufficient electroconductivity, and if it exceeds 97 mass%, the fluidity of a paste will be impaired and it will become difficult to provide printability. More preferably, it is 88-95 mass%.
The organic binder resin in the conductive paste of the present embodiment imparts printing aptitude, and remains even after applying, drying and curing the conductive paste, and has good physical properties such as good adhesion to the base material of the conductive pattern, bending resistance, and hardness. Used to get.
Such organic binder resin is not particularly limited as long as it can impart printing aptitude to the conductive paste, but thermosetting resins, thermoplastic resins, and heat-drying resins capable of pattern formation (solidification) at low temperatures without using photocuring are preferable. Is used. For example, phenoxy resins, acrylic resins, polyvinyl butyral resins are particularly preferable, and various modified polyesters such as polyester resins, urethane modified polyester resins, epoxy modified polyester resins, acrylic modified polyester resins, and the like. Resin, polyether urethane resin, polycarbonate urethane resin, acrylic urethane resin, vinyl chloride vinyl acetate copolymer, epoxy resin, phenol resin, polyamideimide, polyimide, polyamide, nitrocellulose, cellulose acetate butyrate (CAB ), And modified celluloses such as cellulose acetate propionate (CAP). Such resin can be used individually or in combination of 2 or more types as organic binder resin.
In order to impart characteristics such as solvent resistance and high hardness to the formed pattern, a binder resin having a three-dimensional crosslinkable functional group (for example, a carboxyl group or a hydroxyl group) may be used. Among these, it is especially preferable to contain the carboxylic acid containing resin which contains 2 or more of carboxyl groups in at least 1 molecule. Specific examples of such carboxylic acid-containing resins include, but are not limited to, those listed below.
(1) Carboxyl group-containing resin obtained by copolymerizing one or more types of unsaturated carboxylic acids, such as (meth) acrylic acid, and the compound which has an unsaturated double bond other than that.
(2) Monofunctional epoxy compounds, such as butylglycidyl ether and phenylglycidyl ether, are added to one or more types of copolymers of unsaturated carboxylic acids, such as (meth) acrylic acid, and the compound which has another unsaturated double bond. Carboxyl group-containing resin obtained by making it.
(3) to a copolymer of a compound having an unsaturated double bond with an epoxy group such as glycidyl (meth) acrylate or 3,4-epoxycyclohexylmethyl (meth) acrylate and a compound having an unsaturated double bond other than that Carboxyl group-containing resin obtained by making saturated carboxylic acid, such as a propionic acid, react, and making polybasic acid anhydride react with the produced | generated secondary hydroxyl group.
(4) The carboxyl group-containing resin obtained by making the copolymer of the acid anhydride which has unsaturated double bonds, such as maleic anhydride, and the compound which has hydroxyl groups, such as butyl alcohol, react with the copolymer of the compound which has another unsaturated double bond.
(5) Carboxyl group-containing resin obtained by making a polyfunctional epoxy compound and saturated monocarboxylic acid react, and making a produced hydroxyl group react with saturated or unsaturated polybasic anhydride.
(6) A hydroxyl group and a carboxyl group-containing resin obtained by making a saturated or unsaturated polybasic acid anhydride react with hydroxyl-containing polymers, such as a polyvinyl alcohol derivative.
(7) A saturated or unsaturated polybasic acid anhydride is added to the reaction product of a polyfunctional epoxy compound, a saturated monocarboxylic acid, and a compound having at least one alcoholic hydroxyl group and one reactive group other than the alcoholic hydroxyl group reacting with the epoxy group in one molecule. Carboxyl group containing resin obtained by making it react.
(8) Carboxyl group content obtained by making saturated monocarboxylic acid react with the polyfunctional oxetane compound which has at least 2 oxetane ring in 1 molecule, and making a saturated or unsaturated polybasic acid anhydride react with the primary hydroxyl group in obtained modified oxetane resin. Suzy.
(9) A carboxyl group-containing resin obtained by further reacting a compound having one oxirane ring in a molecule with a carboxyl group-containing resin obtained by reacting a saturated monocarboxylic acid with a polyfunctional epoxy resin and then reacting a polybasic anhydride.
Among these, it is preferable to use the carboxyl group-containing resin of (1), (2), and (3) especially. By these, molecular weight, a glass transition point, etc. can be adjusted arbitrarily, and it is possible to adjust the printability of an electrically conductive paste, and to control adhesiveness with respect to a base material suitably.
Moreover, it is preferable that the acid value of such carboxyl group-containing resin is 40-200 mgKOH / g. When the acid value of the carboxyl group-containing resin is less than 40 mgKOH / g, the cohesive force of the conductive paste is lowered, and it is easy to cause a transition defect during printing. On the other hand, when it exceeds 200 mgKOH / g, the viscosity of an electrically conductive paste becomes high too much and it is difficult to provide printability, for example, it is necessary to mix | blend a large amount of crosslinking agents. And more preferably 45 to 150 mgKOH / g.
Moreover, when using a resin film for a base material, it is a polyester resin, an acrylic resin, a polyvinyl butyral resin, a modified polyester resin, a vinyl chloride vinyl acetate copolymer, a copolymer poly from a bending resistance and adhesiveness with respect to a base material. Ester resin etc. are preferable.
Among these, it is preferable to have a hydroxyl group and a carboxyl group in a side chain from a viewpoint of high precision printing and low resistance, As a specific example, a phenoxy resin, a hydroxyl-containing polyester resin, a polyvinyl butyral resin, a carboxyl group, or a hydroxyl-containing acryl Resin can be mentioned.
As organic binder resin, 3000-50000 are preferable for number average molecular weight (Mn). When the number average molecular weight is less than 3000, transition defects at the time of printing tend to occur, and formation of a favorable conductive pattern becomes difficult. On the other hand, when the number average molecular weight exceeds 50000, beard defects due to the dragging of the paste at the time of printing, undulation of lines, etc. are likely to occur, and printability is deteriorated. More preferably from 5,000 to 30,000.
The number average molecular weight is a value in terms of standard polystyrene measured by gel permeation chromatography (GPC).
In addition, as the organic binder resin, thermosetting properties can be imparted by using a combination of a thermoplastic resin or a thermodrying resin and a thermosetting resin.
Specifically, in the electrically conductive paste of this embodiment, in order to form the three-dimensional mesh chain structure and to improve the solvent resistance and adhesiveness of the pattern formed, the organic binder resin further contains a thermoplastic resin or heat-drying resin in resin. Thermosetting property can also be provided by containing a thermosetting resin as a crosslinking agent which has the reactivity with the functional group of.
The thermosetting resin as the crosslinking agent may react with the functional group of the thermoplastic resin or the heat-drying resin in the organic binder resin without crosslinking the printability, and may be crosslinked. The crosslinking agent is not particularly limited as long as it is a resin that is cured by heating. For example, an epoxy resin, a phenol resin, a melamine resin, an alkyd resin, a polyurethane resin, a polyester resin, an acrylic resin, a polyimide resin, and a modified resin thereof. These can be mentioned, These can be used individually or in combination of 2 or more types. In addition, the oxetane compound which has at least 2 oxetanyl group in a molecule | numerator, etc. are mentioned.
It is preferable to contain the epoxy resin which contains 2 or more glycidyl groups in at least 1 molecule of the thermosetting resin as such a crosslinking agent. As such an epoxy resin, for example, bisphenol A type, hydrogenated bisphenol A type, bisphenol F type, bisphenol S type, phenol novolak type, cresol novolak type, novolak type of bisphenol A, biphenol type, bixylenol type Although well-known epoxy resins, such as a trisphenol methane type, an N-glycidyl type, an N-glycidyl type | mold epoxy resin, and an alicyclic epoxy resin, are mentioned, It is not limited to a specific thing, These are single or 2 types The above can be used in combination. Moreover, as for a thermosetting resin as a crosslinking agent, the number average molecular weight (Mn) less than 3000 is preferable.
The compounding ratio of these epoxy resins is suitably 1-100 mass parts per 100 mass parts of thermoplastic resin or heat-drying resin in organic binder resin, Preferably it is 5-40 mass parts.
In addition, a curing catalyst for promoting the reaction of the thermoplastic resin or the heat-drying resin in the organic binder resin with the thermosetting resin as the crosslinking agent, for example, an amine compound, an imidazole derivative, or the like may be blended.
The organic solvent in the electrically conductive paste of this embodiment is used in order to provide favorable printability. The organic solvent may be any one that can be dissolved without chemical reaction with the organic binder resin described above. Specifically, toluene, xylene, ethyl acetate, butyl acetate, methanol, ethanol, isopropyl alcohol, isobutyl alcohol, 1-butanol, diacetone alcohol, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene Glycol monoethyl ether, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, terpineol, methyl ethyl ketone, carbitol, carbitol acetate, butyl carbitol, and the like. It can mix and use the above.
In addition, a high boiling point solvent having a boiling point in the range of 240 to 330 ° C. at 0.1013 MPa may be used in combination for the purpose of preventing drying of the paste in the printing process and maintaining transition properties.
As such a high boiling point solvent, diamyl benzene (boiling point 260-280 degreeC), triamyl benzene (boiling point 300-320 degreeC), n-dodecanol (boiling point 255-259 degreeC), diethylene glycol (boiling point 245 degreeC), di Ethylene glycol monobutyl ether acetate (boiling point 247 ° C.), diethylene glycol dibutyl ether (boiling point 255 ° C.), diethylene glycol monoacetate (boiling point 250 ° C.), triethylene glycol (boiling point 276 ° C.), triethylene glycol monomethyl ether (Boiling point 249 ° C.), triethylene glycol monoethyl ether (boiling point 256 ° C.), triethylene glycol monobutyl ether (boiling point 271 ° C.), tetraethylene glycol (boiling point 327 ° C.), tetraethylene glycol monobutyl ether (boiling point 304 ° C.) And tripropylene glycol (boiling point 267 ° C), tripropylene glycol monomethyl ether (boiling point 243 ° C), 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (boiling point 253 ° C) and the like. As petroleum hydrocarbons, AF Solvent No. 4 (boiling point 240 to 265 ° C.), No. 5 (boiling point = 275 to 306 ° C.), No. 6 (boiling point 296 to 317 ° C.) and No. 7 259-282 degreeC), 0 solvent H (boiling point 245-265 degreeC), etc. are mentioned, Two or more types of these may be included as needed.
Such an organic solvent is suitably contained so that an electrically conductive paste may become a viscosity suitable for printing.
Moreover, in order to color the electrically conductive paste of this embodiment, a coloring agent can be contained. The kind, shape, etc. of a coloring agent are not specifically limited, A well-known thing can be used. The color of the colorant may be any color that is preferable in order to bring about a decrease in brightness sufficient to suppress external light reflection, for example, in a display application. Preferably, blue, black, black by 3 color mixing, etc. are mentioned.
In particular, black is preferable, and carbon black, solvent black, oil black and the like can be used, but carbon black for coloring materials is suitable for ease of obtaining. For example, carbon black for color materials, such as channel black, furnace black, or lamp black, conductive carbon black, acetylene black, etc. are mentioned.
The compounding quantity of such a coloring agent can obtain favorable printability, and should just be able to color with the target brightness. It is preferable that it is 100 mass parts or less with respect to 100 mass parts of organic binder resin from a viewpoint of printability. When it exceeds 100 mass parts, problems, such as a remarkable increase of a viscosity and too high thixotropic property, arise. More preferably, it is 80 mass parts or less.
Moreover, as a minimum, it is preferable to set it as 5 mass parts or more with respect to 100 mass parts of organic binder resins, for example when using as a display use. When the compounding quantity of a coloring agent is less than 5 mass parts, the brightness of a paste will become high and the visibility of a display will deteriorate. More preferably, it is 10 mass parts or more.
Such a coloring agent can be added in powder or a dispersion liquid.
In the electrically conductive paste of this embodiment, in order to obtain more excellent printability and electroconductivity, the compounding quantity of silver powder, an organic binder resin, and a coloring agent (when it is contained) is based on a mass basis,
(The compounding amount of the silver powder + the compounding amount of the coloring agent) / The compounding amount of the organic binder resin: A
10≤A≤26
It is desirable to satisfy the relationship.
If the A value is less than 10, the conductivity decreases because the proportion of the conductive powder is relatively reduced, and the proportion of the powder component in the paste decreases, making it difficult to make a rheology suitable for printing. The ratio becomes so large that it becomes a paste with high thixotropic properties, and the rheology suitable for printing cannot be achieved. More preferably, 13≤A≤22.
In addition, additives such as metal dispersants, thixotropy-imparting agents, antifoaming agents, leveling agents, surface tension lowering agents, plasticizers, antioxidants, metal deactivators, coupling agents and fillers may be blended within a range that does not impair printability. have.
In such an electrically conductive paste, in order to acquire favorable printability, it is preferable that the density | concentration is 50-1000 dPa * s by the measured value (25 degreeC) by a cone-plate type viscometer. If it is less than 50 dPa * s, there will be too much ratio of the organic solvent in a paste, and transition property will fall and it will become difficult to perform favorable printing. On the other hand, when it exceeds 1000 dPa * s, it is difficult to fill a plate, and the scraping property to a doctor blade deteriorates, and background contamination (adhesion of a paste to a non-stitched part) tends to occur. More preferably 100 to 650 dPa · s. Moreover, it can also be diluted suitably so that it may become such concentration at the time of printing.
Moreover, it is preferable that the tag value which shows the dynamic adhesiveness of such an electrically conductive paste is 5-35. If the tag value is less than 5, transferability at the time of printing is inferior and print quality may deteriorate. On the other hand, when the tag value exceeds 35, picking of the to-be-printed object (the tearing of the to-be-printed object) or jam (the to-be-printed object is clogged with the printer) tends to occur. More preferably from 10 to 30. In addition, a tag value is the value measured on the conditions of 30 degreeC and 400 revolutions using the rotary tachometer (common name: Incometer).
Using such an electrically conductive paste, a conductive pattern is formed as follows, for example. First, the coating film pattern of an electrically conductive paste is formed on a base material by printing. As a printing method, well-known printing methods, such as screen printing, gravure printing, and gravure offset printing, can be used. At this time, in addition to a printed wiring board and a glass substrate, flexible substrates, such as PET film, can be used as a base material.
Thus, the coating film pattern formed on the base material is dried at 60-120 degreeC for 1 to 60 minutes, and then baked at 100-250 degreeC for 1 to 60 minutes at low temperature, hardening a coating film pattern and forming a conductive pattern.
In this manner, a good pattern shape can be obtained, and a conductive pattern with low resistance and high solvent resistance can be obtained. Further, since such a conductive pattern can be obtained without high-temperature baking, it can be used as an electrode of a flexible substrate or a device having low heat resistance.
<Examples>
Hereinafter, although an Example and a comparative example demonstrate this embodiment concretely, this invention is not limited to these Examples. In addition, the following compounding quantities are taken as a mass reference | standard unless there is particular notice.
[Production of Conductive Paste]
Using the spherical silver powder shown in Table 1, the electrically conductive paste of Examples 1-5 and Comparative Examples 1-4 was manufactured.
First, 1500 parts by weight of silver powder, 100 parts by weight of polyvinyl butyral resin (manufactured by Esrek BL-1 Sekisui Kagaku Kogyo Co., Ltd.) as an organic binder resin, and carbon black (manufactured by MA-100 Mitsubishi Chemical Corporation) as a colorant ) Is 30 parts by weight and diethylene glycol monoethyl ether acetate as 200 parts by weight as an organic solvent.
And these were mixed, it was ground by the triaxial roll mill, and the electrically conductive paste was obtained. In addition, the viscosity of the obtained electrically conductive paste was adjusted to 500 dPa * s using the organic solvent. The silver content rate of the obtained paste was 92 mass% after volatilizing and drying 82 mass% and a solvent in a paste.
Figure 112012024711912-pat00001
Moreover, using the silver powder used for Example 1, the electrically conductive paste from which silver content rate differs was produced as shown in Table 2. In addition, what was used for Examples 1-5 was used for the organic binder resin and the coloring agent, and the thing which triethylene glycol monobutyl ether was added to diethylene glycol monoethyl ether acetate was used for the organic solvent.
Moreover, in the electrically conductive paste manufactured in this way, the silver content rate in the paste of Example 6 was 93 mass% after volatilizing a solvent and 82 mass%. Silver content rate in the paste of Example 7 was 85 mass%, and after volatilizing a solvent, it was 94 mass%. In addition, the silver content rate in the paste of Example 8 was 88 mass% after volatilizing a solvent and 74 mass%.
Figure 112012024711912-pat00002
* 1: diethylene glycol monoethyl ether acetate
* 2: triethylene glycol monobutyl ether
[Measurement of specific resistance value]
Thus, using each electrically conductive paste obtained, the paste pattern of 1 mm x 40 cm was formed on the glass substrate by screen printing, respectively. Subsequently, the paste pattern was dried at 120 ° C for 30 minutes (cold heat treatment) to form a conductive pattern of 1 mm × 40 cm.
Thus, the resistance value was measured with respect to each electrically conductive pattern obtained by the 4-terminal method using a Milio Ohm high tester, and the specific resistance value was computed from the resistance value and the film thickness. Table 3 shows the specific resistance of each conductive pattern.
Figure 112012024711912-pat00003
In the conductive pattern using a conductive paste of Examples 1 to 7 As shown in Table 3, it was whose specific resistance 10 -5 Ω · cm order. In the conductive pattern using the conductive paste of Example 8, even when the silver content in the paste was reduced, conduction was obtained. On the other hand, in the conductive patterns using the conductive pastes of Comparative Examples 1 to 4, all had high resistance, and in particular, in Comparative Examples 2 and 4, no conduction was obtained.
[Printability Assessment]
The gravure printing aptitude was tested using Examples 1-5 and Comparative Examples 2,3. Using each obtained electroconductive paste, the lattice paste pattern was formed on the 100-micrometer-thick polyester film (Cosmoshine A4300 Toyobo Co., Ltd.) by gravure printing. The chromium-plated intaglio used at this time had a lattice pattern having a line width of 23 μm, a plate depth of 13 μm, and a pitch of 250 μm.
The obtained paste pattern was dried at 120 degreeC for 30 minutes (low temperature heat processing), and the translucent conductive film which formed the grid | lattice-shaped conductive pattern was produced.
For each of the light-transmissive conductive films produced in this way, the grid-like conductive pattern was observed, and the presence or absence of background contamination (adhesion of the paste to the non-stitched portion), beard defects, and scratches were evaluated. Table 3 shows the evaluation results. The evaluation criteria are as follows.
Good: No background contamination, beard defects, or scratches.
Poor: At least one of the following: background contamination, beard defect, scratches.
In addition, sheet resistance was also measured using Lorestar-EP (made by Mitsubishi Chemical Corporation).
Figure 112012024711912-pat00004
As shown in Table 4, it can be seen that by using the conductive paste of the example, both of good printability and low sheet resistance can be achieved. On the other hand, in Comparative Example 2, the printability was good, but the sheet resistance value was high. In Comparative Example 3, the pattern lacked the compactness, the printability was poor, and the sheet resistance value was also significantly high.
Next, the Example using a thermosetting resin is shown below.
[Synthesis of Organic Binder Resin]
(Synthesis of carboxyl group-containing urethane resin)
A polycarbonate diol derived from 1,5-pentanediol and 1,6-hexanediol as a polyol component (Asahi Kasei Chemicals, T5650J, number average molecular weight 800) was placed in a reaction vessel equipped with a stirring device, a thermometer, and a condenser. 288 g (0.36 mol), bisphenol A propylene oxide modified adduct diol (made by Adeka, BPX33, number average molecular weight 500) 45 g (0.09 mol), 81.4 g of dimethylol butanoic acid as dimethylol alkanoic acid (0.55 mol) and 11.8 g (0.16 mol) of n-butanol as a molecular weight modifier (terminal sealant), and 250 g of carbitol acetate (manufactured by Daicel Chemical Industries, Ltd.) as a solvent, were charged at 60 ° C. Dissolved.
While stirring this solution, 200.9 g (1.08 mol) of trimethylene diisocyanates were dripped as polyisocyanate by the dropping funnel. After completion of the dropwise addition, the reaction was continued while stirring at 80 ° C, and it was confirmed that the absorption spectrum (2280 cm -1 ) of the isocyanate group was lost in the infrared absorption spectrum, and the reaction was completed. After completion | finish of reaction, carbitol acetate was added so that solid content might be 60weight%, and the urethane resin solution (varnish 1) was obtained.
The weight average molecular weight of the obtained urethane resin was 18300, and the acid value of solid content was 50.3 mgKOH / g. In addition, the weight average molecular weight was calculated | required by the value converted into polystyrene using the gel carrier liquid chromatography (made by HLC-8120 GPC Tosoh Corporation).
(Synthesis of carboxyl group-containing acrylic resin)
Methyl methacrylate and acrylic acid were added to a reaction vessel equipped with a stirring device, a thermometer, a dropping funnel and a condenser at a molar ratio of 0.80: 0.20, triethylene glycol monobutyl ether (boiling point: 271 ° C) as a solvent, and azo as a catalyst. Bisisobutyronitrile was put, and it stirred at 80 degreeC for 6 hours in nitrogen atmosphere, and obtained the acrylic resin solution (varnish 2) whose non volatile matter is 40 weight%. The obtained resin had a number average molecular weight of 15,000, a weight average molecular weight of about 40,000, and an acid value of 97 mgKOH / g. In addition, the weight average molecular weight was calculated | required similarly to varnish 1.
Using the resin varnish, phenoxy resin, and thermosetting resin obtained in the said synthesis example, each component was mix | blended in the compounding ratio shown in Table 5, it was ground by the triaxial roll mill, and the electrically conductive paste of Examples 9-11 was obtained. In addition, the silver content rate in any paste was 94 mass% after volatilizing a solvent.
Figure 112012024711912-pat00005
[Remarks]
* 1: PKHB manufactured by InChem
* 2: jER828 (Bisphenol A epoxy resin, epoxy equivalent = 190 g / eq) by Mitsubishi Chemical Corporation
* 3: Silver powder used in Example 1
* 4: diethylene glycol monoethyl ether acetate
* 5: triethylene glycol monobutyl ether
* 6: 2,4-diamino-6- [2'-methylimidazolyl- (1)]-ethyl-s-triazine isocyanuric acid adduct
&Lt; Evaluation of printability by simple gravure printing >
(Production of sample)
Each obtained electrically conductive paste was filled in the recess of the glass intaglio in which the stripe pattern of line / space = 70/30 micrometers and plate | board depth: 10 micrometers was formed using the steel doctor.
Next, this glass intaglio was placed on a blanket cylinder containing a silicone rubber having a rubber hardness of 30 °, and the conductive paste filled in the recess was transferred to the blanket cylinder surface (off step). Furthermore, the pattern of the electrically conductive paste of the blanket cylinder surface was transferred to the soda-lime glass surface of thickness 1.8mm (setting process).
Thus, the obtained sample was evaluated as follows.
(Printing suitability 1: transferability evaluation)
The setting process was performed 10 second after the off process, and visually evaluated whether the electrically conductive paste remained on the blanket cylinder surface. The evaluation criteria are as follows.
(Circle): There is no remainder of an electrically conductive paste on a blanket surface (100% transfer).
(Triangle | delta): The electrically conductive paste remains in a part of blanket surface.
X: The electrically conductive paste remains on the blanket whole surface.