JP2022035700A - Resin ink and electronic device - Google Patents

Abstract

To provide: a resin ink which is capable of ensuring quality maintenance of a print state even if printing is carried out in the atmosphere; and an electronic device on which the resin ink is printed.SOLUTION: A resin ink according to the present invention is made by mixing a resin material into a solvent to form an ink; and the solvent is a polar organic solvent, a thickening ratio of which is 50% or less when adding 30 pts.mass of water to 100 pts.mass of the solvent.SELECTED DRAWING: Figure 1

Description

The present invention relates to a resin ink obtained by mixing a resin with a solvent to form an ink, and an electronic device on which the resin ink is printed.

In recent years, the manufacturing technology of electronic devices using printing technology is called "Printed electronics" and the like, and is attracting attention as a resource-saving, low-power, low-environmental-load electronic device manufacturing technology.

In the manufacturing technology of such an electronic device, a semiconductor material, a conductive material, an insulating material or another functional material mixed with a solvent and made into an ink (ink composition) is printed on a substrate such as a film. , Forming circuits / elements and devices (see, for example, Patent Document 1 below).

Japanese Unexamined Patent Publication No. 2017-197765

When forming an electronic circuit by using a printing method, printing methods such as screen printing, gravure offset printing, flexographic printing, and inkjet printing are used. In each printing method, an ink composition capable of forming an optimum film formation is possible. The range of viscosity of an object is fixed. Therefore, the viscosity of the ink composition is adjusted to have an appropriate range for the printing method to be used. Therefore, if the viscosity of the ink composition changes significantly, the shape of the print pattern is disturbed, the smoothness of the printed resin layer is lowered, and the like, and circuits, elements, devices, and the like cannot be formed in a desired printing state. ..

In the manufacture of electronic circuits, maintaining the quality of the printed state is indispensable in order not to cause problems such as short circuit of the circuit and deterioration of electrical characteristics. Will cause a decrease in.

The inventors have found that in a specific solvent constituting the ink composition, the viscosity of the ink composition changes significantly by absorbing moisture. In particular, the inventors have found that in a high-viscosity ink composition (resin ink) in which a resin is dissolved in a solvent, the viscosity significantly fluctuates due to the influence of moisture absorption when a specific polar organic solvent is used, resulting in a printing state. It was found that the quality of the ink was impaired.

The present invention has been proposed in order to avoid deterioration of the quality of the printed state in the manufacture of electronic circuits in the process in which the resin ink is used. That is, it is an object of the present invention to provide a resin ink capable of ensuring quality maintenance in a printed state even when printing in the atmosphere, and an electronic device on which the resin ink is printed.

In order to solve such a problem, the present invention has the following configurations.

That is, the resin ink of the present invention is a resin ink obtained by mixing a resin material with a solvent to form an ink, and the solvent has a thickening rate when 30 parts by mass of water is added to 100 parts by mass of the solvent. It is characterized in that it is a polar organic solvent having a value of 50% or less.

Preferably, the solvent is characterized in that the solubility of water is 500 g / L or less.

Preferably, the solvent is a saturated cyclic compound having a carbonyl group (including one having an oxygen atom as a hetero atom in the ring skeleton) or a chain skeleton having a carbonyl group and having 5 or more carbon atoms. It is characterized by being a polar organic solvent which is a saturated chain compound (including a compound having an oxygen atom as a hetero atom in the chain skeleton).

Preferably, the resin material is a fluororesin.

The electronic device of the present invention is printed with the resin ink of the present invention.

According to the present invention, it is possible to provide a resin ink capable of ensuring quality maintenance in a printed state even when printing in the atmosphere and an electronic device on which the resin ink is printed.

It is a figure which shows the result of Experiment 2 (viscosity change in a printing process of a fluororesin ink). It is a figure which shows the result of Experiment 3 (viscosity change by moisture absorption of polyvinyl phenol ink).

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Resin ink)
The resin ink of the present embodiment is a paste-like composition (ink composition) in which a resin material is mixed (dissolved or dispersed) in a solvent to form an ink, and is mainly used in the manufacture of electronic circuits using a printing device. , Used as an ink for printing various patterns such as desired circuit patterns on a substrate. Some such resin inks include a resin material having a polar group and a polar organic solvent having excellent compatibility (or miscibility) with the resin material.

(Polar organic solvent)
The polar organic solvent is, for example, a cyclic or chain type (linear or chain type) having one or more polar groups such as a carbonyl group, an ester group, a hydroxy group, a phosphoric acid group, a sulfinyl group, an amino group and an amide group. Branched chain) compound.

Examples of polar organic solvents are saturated cyclic compounds having a carbonyl group (including those having an oxygen atom as a hetero atom in the ring skeleton) (compounds 1 to 5 below) and saturated cyclic compounds having a nitrogen atom (compounds below). 6-8), unsaturated cyclic compounds having a carbonyl group (compounds 9 to 24 below), saturated chain compounds having a carbonyl group (including those having an oxygen atom as a hetero atom in the chain skeleton) (compounds below). 25 to 51), chain compounds having a nitrogen atom (compound 52 below), chain compounds having a phosphate group (compound 53 below), chain compounds having a sulfinyl group (compound 54 below) and the like can be mentioned.

Among such polar organic solvents, the polar organic solvent in the resin ink of the present embodiment is thickened even if it absorbs moisture in order to prevent the viscosity from changing significantly due to moisture absorption in the printing process. It is a polar organic solvent that does not absorb moisture or does not easily absorb moisture. Since the degree of moisture absorption is affected by the environment and the amount of exposure to the atmosphere (printing work time), it is necessary to select a solvent having a low thickening rate even when mixed with an excessive amount of water. Specifically, a polar organic solvent having a thickening ratio of 50% or less when 30 parts by mass of water is added to 100 parts by mass of the polar organic solvent is used. In the present embodiment, the "viscosity thickening rate" means the ratio of the viscosity change due to moisture absorption to the viscosity of the solvent. For example, when the viscosity of the solvent alone is Da and the viscosity after the solvent absorbs (absorbs) water is Db, the viscosity increase due to the absorption of the solvent is Db ÷ Da × 100-100 (%). be.

In the present embodiment, the polar organic solvent used as the solvent for the resin ink includes saturated cyclic compounds having a carbonyl group (including those having an oxygen atom as a hetero atom in the ring skeleton) (for example, compounds 1 to 5). Saturated chain compounds having a carbonyl group and having 5 or more carbon atoms in the chain skeleton (including those having an oxygen atom as a hetero atom in the chain skeleton) (for example, compounds 26 to 51), chains having a phosphate group. Formula compounds (eg, compound 53) and the like can be mentioned.

[Compound 1] Cyclohexanone [Compound 2] Cycloheptanone [Compound 3] 3,3,5-trimethylcyclohexanone [Compound 4] γ-Butyrolactone [Compound 5] Propropylene Carbonate [Compound 6] NMP (1-Methyl-2-) Pyrrolidone)
[Compound 7] 1,3-dimethyl-2-imidazolidinone [Compound 8] N, N-dimethylcyclohexylamine [Compound 9] Isophorone

[Compound 10] 2-Methoxy-4-methylphenol [Compound 11] Methyl salicylate (methyl salicylate)
[Compound 12] 2'-Hydroxyacetophenone [Compound 13] Benzaldehyde [Compound 14] p-tolualdehyde [Compound 15] Acetphenone [Compound 16] 4'-Methylacetophenone [Compound 17] 4-Ethylbenzaldehyde [Compound 18] 4' -Ethylacetophenone [Compound 19] Methyl benzoate (Methylbenzoate)

[Compound 20] Ethyl benzoate (ethylbenzoate)
[Compound 21] Methyl p-toluate [Compound 22] Propylbenzoate [Compound 23] Ethyl p-toluate [Compound 24] Butylbenzoate [Compound 25] MEK (2-butanone)
[Compound 26] 2-Pentanone [Compound 27] 2-Hexanone [Compound 28] 2-Heptanone [Compound 29] 2-Octanone

[Compound 30] 2-Nonanone [Compound 31] 2-Decanone [Compound 32] Nonanal [Compound 33] 2-ethoxyethyl acetate [Compound 34] Ethylene glycol monobutyl ether acetate [Compound 35] Diethylene glycol monoethyl ether acetate [Compound 36] Diethylene glycol monobutyl ether acetate [Compound 37] propylhexanoate [Compound 38] propyl n-octanoate [Compound 39] ethyl n-octanoate

[Compound 40] Methyldecanoate [Compound 41] 2-Ethylhexyl acetate [Compound 42] 3,4-Hexanedione [Compound 43] diethyl oxalate [Compound 44] Dibutyl oxalate [Compound 45] Acetylacetone [Compound 46] Methyl Acetoacetate [Compound 47] Diethylmalonate [Compound 48] Acetonylacetone [Compound 49] Ethylene glycol diacetate

[Compound 50] 1,2-Diacetoxypropane [Compound 51] 2,6-dimethyl-4-heptanone [Compound 52] Tetramethylurea [Compound 53] Trimethyl phosphate [Compound 54] DMSO (dimethyl sulfoxide)

In an ink having a high resin concentration and a high viscosity, a change in viscosity due to moisture absorption is likely to occur. Therefore, it is preferable to select a solvent having a smaller viscosity increase rate when water is added.

(Resin material)
Examples of the resin material contained in the resin ink include fluororesins (polyvinylidene fluoride trifluoride (PVDF-TrFE), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), etc.) and polyvinylphenol (PVP). Examples thereof include one or more resin materials having a polar group such as an insulating resin such as a resin.

The weight ratio of the resin material in the resin ink (ink composition) varies depending on the required viscosity and the target film thickness, so there is no particular optimum value. It is preferable to select a solvent having a smaller viscosity when water is added, because it is more likely to occur.

(Other materials)
Other materials to be mixed with polar organic solvents include, for example, conductive particles (eg, copper, zinc, chromium, platinum, gold, silver, aluminum, palladium, iron, cobalt, nickel, or their metal oxides, carbon. One or more of additives (eg, wetting agents, dispersants, defoaming agents, adhesion promoters, corrosion inhibitors, stabilizers, surfactants, etc.), additives (particles consisting of one or more materials such as materials) (Those consisting of two or more types) and the like may be further included.

(substrate)
Examples of the substrate (base material) of the object to be printed on which various patterns such as circuit patterns are printed by the resin ink include flexible substrates made of resin such as polyimide, polyethylene terephthalate (PET), and polyethylene naphthalate (PEN). Examples include ceramics (alumina, aluminum nitride, etc.), glass, paper, and the like.

(Electronic device)
The resin ink of this embodiment is used when printing various patterns such as a desired circuit pattern on a substrate (base material). Examples of electronic devices on which such resin ink (pattern) is printed include semiconductors, electronic displays, electronic circuits (print circuits, etc.), sensors, and the like. Printing of this pattern is, for example, screen printing method, inkjet printing method, letterpress reversal printing method, gravure offset printing method, offset printing method, spin coating method, spray coating method, bar coating method, die coating method, slit coating method, roll coating method. It is performed by a method such as a method or a dip coat method.

Hereinafter, the present invention will be described in detail with reference to examples. However, the present invention is not limited to this embodiment.

(Experiment 1: Change in viscosity due to water content with respect to solvent)
For polar organic solvents having polar groups with different structures, the effect of changes in viscosity due to water content on the solvent was investigated.

Fifteen types of polar organic solvents were selected as solvent candidates for the resin ink (polar organic solvents of numbers [1] to [15] shown in [Table 1] and [Table 2]). For each of the polar organic solvents Nos. [1] to [15], the viscosity of only the polar organic solvent is D ₁ , and 30 parts by mass of ultrapure water is mixed with 100 parts by mass of the polar organic solvent. The viscosity of the polar organic solvent was D ₂ , and the thickening rate (D ₂ ÷ D ₁ × 100-100) (%) of the polar organic solvent calculated from D ₁ and D ₂ was calculated.

Viscosity D ₁ and viscosity D ₂ were measured using a rotary viscometer (DV-3T: LV) manufactured by Brookfield. The spindle used was a cone plate type spindle (CPA-40). Viscosity D ₁ and viscosity D ₂ were measured when the spindle was rotated at 50 rpm while the temperature was maintained at 25 ° C.

In addition, as a reference, the solubility in water described in the literature such as the solvent handbook is also shown. The results of this experiment 1 are shown in [Table 1] and [Table 2].

As shown in [Table 1] and [Table 2], of No. [4] (Compound 6), No. [8] (Compound 8), No. [9] (Compound 25), No. [10] (Compound 52). Since the thickening rate of the polar organic solvent exceeded 50%, it was confirmed that the state change was large by mixing 30 parts by mass of water with 100 parts by mass of the polar organic solvent.

Further, the numbers [4] (Compound 6), No. [8] (Compound 8), and No. [10] (Compound 52) are structures containing nitrogen atoms such as an amino group and an amine group, and have such a structure. It was found that the thickening rate of this compound was large.

The polar organic solvents of No. [3] (Compound 4), No. [14] (Compound 35), and No. [15] (Compound 53) have high affinity with water (solubility in water (g / L)). Nevertheless, the thickening rate was 50% or less, and it was found that it could be applied as a solvent for resin ink.

The polar organic solvents of Nos. [5] (Compound 9), No. [6] (Compound 19), and No. [7] (Compound 11) were added to the layer of the polar organic solvent and the layer of water when water was mixed. Although they were separated and the viscosity D ₂ and the thickening rate could not be measured accurately, the viscosity D ₂ was almost the same value as the viscosity D ₁ , and no large increase in the viscosity was observed.

From the results of Experiment 1 above, No. [1] (Compound 1), No. [2] (Compound 3), and No. [3] (Compound 4) (saturated cyclic compound having a carbonyl group (in the ring skeleton). (Including those having an oxygen atom as a hetero atom)) and the polar organic solvent of No. [11] (Compound 33), No. [12] (Compound 46), No. [13] (Compound 47), No. [14] ( Compound 35) (a chain saturated chain compound having a carbonyl group and having 5 or more carbon atoms in the chain skeleton (having an oxygen atom as a hetero atom in the chain skeleton)) and the number [15]. It can be seen that the polar organic compound of (Compound 53) (chain compound having a phosphoric acid group) is suitable as a solvent for the resin ink.

(Experiment 2: Viscosity change in the printing process of fluororesin ink)
The two types of polar organic solvents confirmed in Experiment 1 (No. [2] (Compound 3) and No. [4] (Compound 6)) were each subjected to polyvinylidene fluoride trifluoride (PVDF-TrFE), which is a fluororesin. PVDF-TrF ink was prepared as a fluororesin ink by mixing with a copolymer, and it was confirmed whether the viscosity of PVDF-TrF ink changed before and after printing using the adjusted PVDF-TrF ink.

Specifically, the powder of the polyvinylidene fluoride (PVDF-TrFE) copolymer, which is a fluororesin, is mixed with the polar organic solvents of No. [2] (Compound 3) and No. [4] (Compound 6). Then, two types of PVDF-TrFE ink (fluororesin ink) having a resin concentration of 18 wt% were adjusted.

As a printing device, a screen printing device SSA-PC250E-IP manufactured by Ceria Co., Ltd. was used. In this printing apparatus, a mask (plate) having a printing area of 100 mm × 100 mm and a plate frame size of 320 mm × 320 mm was used, and screen printing was performed with a squeegee moving speed of 10 mm / s.

The viscosities of the two prepared PVDF-TrFE inks in the initial state before screen printing were measured.

Next, each of the two prepared PVDF-TrFE inks is filled in the screen printing device, and screen printing is continuously performed on the PEN substrate which is the 10 sheets to be printed (that is, 10 times of printing), and then the mask is performed. The PVDF-TrFE ink remaining on the (plate) was collected and its viscosity was measured. Since the time required for printing is about 3 minutes for one printed matter, it takes about 30 to 40 minutes for 10 printed matter, during which the PVDF-TrFE ink has a working atmosphere in this printing process. It was exposed (hygroscopic) to the atmosphere inside. The temperature and humidity of this working atmosphere were 25 ° C. and 50% humidity (relative humidity) RH.

In this way, regarding the viscosities of the two types of PVDF-TrFE inks, by measuring the viscosities in the initial state and the viscosities after 10 printings, the moisture in the atmosphere during the 10th printing operation was absorbed. The change in viscosity of PVDF-TrFE ink was investigated. A rotary viscometer (DV-2T: HV) manufactured by Brookfield Co., Ltd. was used for measuring the viscosity. The result of this experiment 2 is shown in FIG.

FIG. 1 shows the viscosity (mPa · s) with respect to the rotation speed (rpm) of the rotor. In FIG. ₁ , the broken line a1 indicates the viscosity (mPa · s) with respect to the rotation speed (rpm) before printing (initial state) in the PVDF-TrFE ink using the polar organic solvent of No. [2] (Compound 3). ), The solid line a2 is the viscosity (mPa · s) with respect to the rotation speed (rpm) in the state after printing 10 times in the PVDF-TrFE ink using the polar organic solvent of No. [ ₂ ] (Compound 3). Is shown.

Further, the broken line b1 indicates the viscosity (mPa · s) with respect to the rotation speed (rpm) before printing (initial state) in the PVDF-TrFE ink using the polar organic solvent of No. [ ₄ ] (Compound 6). , Solid line b ₂ shows the viscosity (mPa · s) with respect to the rotation speed (rpm) in the state after printing 10 times in the PVDF-TrFE ink using the polar organic solvent of No. [4] (Compound 6). There is.

As shown by the broken line a1 and the solid line _a2 in FIG. ₁ , the PVDF-TrFE ink using the polar organic solvent of No. [2] (Compound 3) having a small change in viscosity when mixed with water in Experiment 1 Compared with the viscosity in the initial state (dashed line a1), the viscosity after ₁₀ printings (solid line _a2 ) hardly changed.

On the other hand, as shown by the broken line b1 and the solid line b2 in _FIG . ₁ , the PVDF-TrFE ink using the polar organic solvent of No. [4] (Compound 6) having a large change in viscosity when mixed with water in Experiment 1 Then, the viscosity after 10 printings (solid line b ₂ ) changed more than twice as much as the viscosity in the initial state (dashed line b ₁ ).

As described above, a hygroscopic polar organic solvent (No. [4] (Compound 6)) was used rather than a PVDF-TrFE ink using a non-moisture-absorbing polar organic solvent (No. [2] (Compound 3)). PVDF-TrFE ink had a greater thickening in the printing process. From this, it can be seen that the PVDF-TrFE ink absorbs moisture and thickens due to the atmosphere in the working atmosphere in the printing process.

(Experiment 3: Viscosity change due to moisture absorption of polyvinylphenol ink)
The two types of polar organic solvents confirmed in Experiment 1 (No. [2] (Compound 3) and No. [4] (Compound 6)) were mixed with polyvinylphenol (PVP), which is an insulating resin, respectively. PVP ink was adjusted as the insulating resin ink, and it was confirmed whether or not the viscosity of the insulating resin ink changed due to moisture absorption.

Specifically, PVP ink, which is an insulating resin, is mixed with each polar organic solvent of No. [2] (Compound 3) and No. [4] (Compound 6), and the resin concentration is 10 wt%. Two types of (insulating resin ink) were adjusted.

The viscosities of the two prepared PVP inks before adding ultrapure water were measured.

Next, for each of the two prepared PVP inks, 5 parts by mass of ultrapure water was added to 100 parts by mass of the PVP ink, and the viscosity in that state was measured.

In this way, regarding the viscosity of the two types of PVP ink, by measuring the viscosity before the addition of water (ultrapure water) and the viscosity after the addition of water (ultrapure water), the PVP ink due to moisture absorption during the printing operation. The change in the viscosity of the ink was investigated. The result of this experiment 3 is shown in FIG.

Also in FIG. 2, the viscosity (mPa · s) with respect to the rotation speed (rpm) of the rotor is shown. In FIG. 2, the broken line c ₁ indicates the viscosity (mPa · s) with respect to the rotation speed (rpm) before water addition in the PVP ink using the polar organic solvent of No. [2] (Compound 3), and is a solid line. c ₂ indicates the viscosity (mPa · s) with respect to the rotation speed (rpm) after the addition of water in the PVP ink using the polar organic solvent of No. [2] (Compound 3).

Further, the broken line d ₁ indicates the viscosity (mPa · s) with respect to the rotation speed (rpm) before water addition in the PVP ink using the polar organic solvent of No. [4] (Compound 6), and the solid line d ₂ is. , No. [4] (Compound 6) shows the viscosity (mPa · s) with respect to the number of revolutions (rpm) in the state after water addition in the PVP ink using the polar organic solvent.

As shown by the broken line c ₁ and the solid line c ₂ in FIG. 2, in the PVP ink using the polar organic solvent of No. [2] (Compound 3), water was added before water was added (broken line c ₁ ). Almost no change in viscosity was observed after (solid line c ₂ ).

On the other hand, as shown by the broken line d1 and the solid line d2 in _FIG . ₂ , the PVP ink using the polar organic solvent of No. [4] (Compound ₆ ) is compared with that before water is added (broken line d1). After adding water (solid line d ₂ ), it was confirmed that the ink was greatly thickened and the state of the ink changed.

As described above, the PVP ink using the hygroscopic polar organic solvent (No. [4] (Compound 6)) is more than the PVP ink using the non-hygroscopic polar organic solvent (No. [2] (Compound 3)). The thickening was greater in. From this, it was found that the PVP ink also thickened by moisture absorption.

Claims (5)

A resin ink made by mixing a resin material with a solvent to make ink.
The solvent is a resin ink characterized by being a polar organic solvent having a thickening rate of 50% or less when 30 parts by mass of water is added to 100 parts by mass of the solvent. The resin ink according to claim 1, wherein the solvent has a solubility of water of 500 g / L or less. The solvent is a saturated cyclic compound having a carbonyl group (including one having an oxygen atom as a hetero atom in the ring skeleton), or a saturated chain compound having a carbonyl group and having a chain skeleton having 5 or more carbon atoms. The resin ink according to claim 1 or 2, which is a polar organic solvent (including one having an oxygen atom as a hetero atom in a chain skeleton). The resin ink according to any one of claims 1 to 3, wherein the resin material is a fluororesin. An electronic device on which the resin ink according to any one of claims 1 to 4 is printed.

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