JP7093235B2 - A dispersion composition containing metal nanoparticles and a molded product thereof. - Google Patents

Description

The present invention relates to a dispersion composition, an ink, a paint, a coating film, and a molded product obtained by using the dispersion composition.

Since metal nanoparticles have physical and chemical properties different from those of bulk metals, they are used in various industrial materials such as electrode materials, high-density recording materials, and ink materials for inkjet. A dispersion composition in which metal nanoparticles are dispersed in a non-aqueous solvent and a binder resin is processed into an ink, a paint, or the like, which is applied onto a substrate and then dried to form a coating film. As the metal nanoparticles in the dispersion composition have a smaller particle size, the surface energy is higher and aggregation is more likely to occur, so that a dispersant is widely used.

As a prior art, a conductive paste containing an acid-based dispersant having a molecular weight of 500 or less, a conductive powder, a ceramic powder, a binder resin and an organic solvent is disclosed (Patent Document 1). Further, a conductive paste containing a polymer-based ionic dispersant, a conductive powder, a binder resin, and an organic solvent is disclosed (Patent Document 2). These conductive pastes did not solve the problem of thickening during transportation and storage.

International Publication No. 2017/150438 Japanese Unexamined Patent Publication No. 2010-135180

An object of the present invention is to provide a dispersion composition which prevents aggregation of metal nanoparticles and has excellent dispersibility and dispersion stability.

As a result of diligent research by the present inventor, it is a dispersion composition containing a dispersant, metal nanoparticles, a non-aqueous solvent, and a binder resin, and the dispersant is a poly having an average degree of polymerization of 2 to 20. It has been found that a dispersion composition containing an ester compound of glycerin and at least one monovalent carboxylic acid and at least one divalent carboxylic acid or a derivative thereof can solve the above-mentioned problems.

The dispersion composition of the present invention finely disperses metal nanoparticles and is excellent in stability over time. Further, the coating film obtained by using the dispersion composition is excellent in smoothness.

Hereinafter, embodiments for practicing the present invention will be described in more detail, but the scope of the present invention is not limited to this embodiment, and changes and the like have been made to the extent that the gist of the present invention is not impaired. The form also belongs to the present invention. In addition, "-" representing a range includes an upper limit and a lower limit.

The dispersant of the present invention is an ester compound having an average degree of polymerization of polyglycerin of 2 to 20, at least one monovalent carboxylic acid, and at least one divalent carboxylic acid or a derivative thereof. It is characterized by that.

The polyglycerin is a polyglycerin having an average degree of polymerization of 2 to 20 calculated from the hydroxyl value, and a polyglycerin having an average degree of polymerization of 2 to 10 is preferable. Here, the average degree of polymerization is the average degree of polymerization (n) of polyglycerin calculated from the hydroxyl value by the end group analysis method. Specifically, the average degree of polymerization is calculated from the following equations (Equation 1) and (Equation 2).
(Equation 1) Molecular weight = 74n + 18
(Equation 2) Hydroxyl group value = 56110 (n + 2) / molecular weight The hydroxyl group value in the above (Equation 2) is a numerical value that is an index of the number of hydroxyl groups contained in polyglycerin and is contained in 1 g of polyglycerin. The number of milligrams of potassium hydroxide required to neutralize the acetic acid required to acetylate free hydroxy groups. The number of milligrams of potassium hydroxide is calculated according to the editorial of the Japan Oil Chemists'Association, "Established by the Japan Oil Chemists' Society, Standard Oil and Fat Analysis Test Method, 2013 Edition".

In the above-mentioned polyglycerin having an average degree of polymerization of 2 to 20, a composition having a molecular weight distribution is generally used, but two or more kinds of polyglycerin having different molecular weight distributions may be mixed, and poly If the average degree of polymerization of the glycerin mixture is 2 to 20, polyglycerin having an average degree of polymerization of more than 20 can also be used.

The monovalent carboxylic acid used in the dispersant of the present invention is not particularly limited, but acetic acid, propionic acid, fatty acid, valeric acid, caproic acid, capric acid, 2-ethylhexanoic acid, isononanoic acid, capric acid, etc. Examples thereof include lauric acid, myristic acid, isomyristic acid, palmitic acid, isopalmitic acid, stearic acid, isostearic acid, ricinoleic acid, oleic acid, linoleic acid, linolenic acid, arachidic acid, isoarakidic acid, behenic acid and erucic acid. Moreover, you may use these acid halogen compounds. Of these, branched fatty acids such as 2-ethylhexanoic acid, isostearic acid and oleic acid, and unsaturated fatty acids are preferable.

The divalent carboxylic acid used in the dispersant is not particularly limited, but is oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and dimethyloctadecane. Examples thereof include carboxylic acids such as diic acid, eicosan diic acid, phthalic acid, isophthalic acid, terephthalic acid, maleic acid, dimer acid, tetrahydrophthalic acid and octenyl succinic acid. Further, these acid anhydrides and acid halides may be used. Of these, divalent carboxylic acids having 4 carbon atoms, such as succinic acid and maleic acid, are preferable.

The esterification rate of the dispersant is preferably 75 to 100% from the viewpoint of the effect of the present invention. When the esterification rate is 75% or more, the affinity with the organic solvent and the binder resin is improved, and the metal nanoparticles can be finely dispersed in the dispersion composition.

The compounding molar ratio of the monovalent carboxylic acid and the divalent carboxylic acid of the dispersant can be selected from 99.99 / 0.01 to 0.01 / 99.99 from the viewpoint of the effect of the present invention. .. Of these, 95/5 to 50/50 is preferable. When the compounding molar ratio of the monovalent carboxylic acid and the divalent carboxylic acid of the dispersant is 99.99 / 0.01 to 0.01 to 99.99, the dispersant has an adsorptive power and three-dimensionality with respect to the metal nanoparticles. Disorderability is obtained, aggregation of metal nanoparticles in the dispersion composition is suppressed, and dispersion stability is excellent.

The blending amount of the dispersant with respect to 100 parts of the metal nanoparticles is preferably 0.01 part to 10 parts, and more preferably 0.1 part to 6 parts.

Examples of the metal nanoparticles contained in the dispersion composition of the present invention include nanoparticles of base metals or noble metals. Examples of the base metal include nickel, titanium, cobalt, copper, chromium, manganese, iron, zirconium, tin, tungsten, molybdenum, vanadium and the like. Examples of the noble metal include gold, silver, platinum, palladium, iridium, osmium, ruthenium, rhodium, renium and alloys containing these metals. Among the base metal or precious metal nanoparticles, palladium, gold, silver, platinum, copper, nickel and titanium are preferable from the viewpoint of conductivity. The metal nanoparticles may further contain elements other than metal elements such as hydrogen, carbon, nitrogen, and sulfur. Further, the above-mentioned two or more kinds of metal nanoparticles may coexist.

The metal nanoparticles are generally particles having a primary particle size of 1 nm to several hundred nm. The shape of the particles is not particularly limited, and examples thereof include a spherical shape, a plate shape, and a fibrous shape. For the particle size, the one obtained by measuring two or more lengths and calculating the average value, or the value calculated by using the geometric formula is used.

The content of the metal nanoparticles in the dispersion composition is usually 0.1% by weight to 80% by weight, preferably 20% by weight to 70% by weight. When the blending amount of the metal nanoparticles is 80% by weight or less, the metal nanoparticles can be wetted with a solvent, and the dispersion composition has excellent dispersibility or dispersion stability.

The non-aqueous solvent contained in the dispersion composition of the present invention is a non-aqueous solvent used in the fields of ink, paint, conductive paste and the like, and is a hydrocarbon-based solvent, an alcohol-based solvent, an ether-based solvent, an ester-based solvent, and the like. A ketone-based or glycol-based solvent can be used. For example, toluene, xylene, octanol, decanol, tarpineol, dihydroterpineol, tarpinyl acetate, dihydroterpinyl acetate, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol mono. Examples thereof include butyl ether, ethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, methyl ethyl ketone, ethylene glycol, propylene glycol, mineral spirit, N-methylpyrrolidone, and γ-butyrolactone. These can be used alone or in combination of two or more, and are preferably tarpineol, dihydroterpineol, or diethylene glycol monobutyl ether in consideration of the handling property of the dispersion composition and the drying property of the coating film.

The binder resin contained in the dispersion composition of the present invention is preferably methyl cellulose, ethyl cellulose, ethyl hydroxyethyl cellulose, nitrocellulose, acrylate, polyvinyl butyral and the like.

The content of the binder resin in the dispersion composition is preferably 0.01% by weight to 15% by weight, more preferably 0.1% by weight to 10% by weight. When the blending amount of the binder resin is 15% by weight or less, the viscosity of the dispersion composition is low, and a coating film having a uniform thickness can be produced.

The binder resin may be directly blended into the dispersion composition, but an organic vehicle in which a binder resin and a non-aqueous solvent are mixed in advance can be prepared and blended into the dispersion composition.

The dispersion composition of the present invention may be blended with various additives such as other dispersants, other surfactants, viscosity modifiers and defoamers as long as the purpose is not impaired.

The dispersion composition, ink, and paint of the present invention can be prepared according to a conventionally known preparation method. For example, stirring, mixing, and dispersion include rocking mills, paint shakers, ball mills, bead mills, roll mills, sand mills, jet mills, homogenizers, rotating and revolving mixers, ultrasonic dispersers, etc., but are limited to these dispersion methods. It's not something. Further, beads such as zirconia beads and alumina beads may be used if necessary.

The coating film of the present invention can be produced by being applied onto a substrate according to a conventionally known preparation method. The substrate is not particularly limited, and examples thereof include a green sheet, glass, a PET film, a polyimide film, and a metal. Examples of the method for applying the dispersion composition, ink, and paint to these substrates include screen printing, flexographic printing, doctor blade method, dip method, reverse roll method, direct roll method, gravure method, dipping method, and brushing. Appropriate methods such as coating method, spray coating, bar coater, knife coater and the like can be mentioned, and a coating film can be obtained through a drying step.

The dispersion composition and the ink, paint, and coating film obtained by using the dispersion composition are, for example, a conductive paste, an electrode material using a conductive ink, a magnetic paste, and a high-density recording material using a magnetic ink. , Used as ink material for inkjet. Examples of the molded product obtained by using these include an internal electrode of MLCC, a printed wiring board, an electromagnetic wave shield, a conductive primer, a conductive tape and the like.

Hereinafter, the present invention will be described in detail, but the present invention is not limited to these examples. Examples and comparative examples of the present invention are shown.

(Synthesis of dispersants A to I)
110.1 g (0.147 mol) of decaglycerin and 390.2 g (1.374 mol) of isostearic acid were placed in a reaction vessel, 0.25 g of sodium hydroxide was added, and then 240 ° C. for 4 hours under a nitrogen stream. The reaction was carried out to obtain 476 g of an esterification reaction product. 476 g of the above ester and 24.5 g (0.245 mol) of succinic anhydride were charged and reacted at 100 ° C. for 3 hours under a nitrogen stream to obtain 500 g of dispersant A having an esterification rate of 92%. Similarly, dispersants B to I were synthesized by changing the types of polyglycerin, fatty acid, and dibasic acid. Details of each dispersant are shown in Table 1.

(Preparation of organic vehicle)
Weigh 36.8 g of tarpineol as a non-aqueous solvent into a mayonnaise bottle, and add 3.2 g of ethyl cellulose (STD-20; Nikkei Seisei Co., Ltd.) as a binder resin little by little while stirring with heating using a hot stirrer to dissolve it. rice field. This was used as an organic vehicle containing 8% by weight of ethyl cellulose.

(Preparation of dispersion composition)
<Example 1>
After weighing 0.28 g of dispersant A in a plastic container for a rotating and revolving mixer, 5.72 g of tarpineol was added to dissolve the dispersant A, and nickel (primary particle size 0.2 μm, Toho titanium stock) as metal nanoparticles was dissolved. Company) was added in an amount of 14 g. 40 g of zirconia beads were added thereto, and the mixture was dispersed at a rotation speed of 2000 rpm for 5 minutes using a rotation / revolution mixer (Awatori Rentaro, Shinky Co., Ltd.). Then, 9.38 g of an organic vehicle and 0.62 g of turpineol were added, and the mixture was dispersed at 2000 rpm for 2 minutes using a rotation / revolution mixer, and the beads were filtered off to obtain the dispersion composition of the present invention.

(Preparation of coating film)
The dispersion composition obtained above was uniformly applied onto a glass substrate using an applicator, dried at room temperature for 5 minutes, and then dried at 150 ° C. for 15 minutes using a dryer to obtain a coating film. ..

<Examples 2 to 11 and Comparative Examples 1 to 4>
In Examples 2 to 11 and Comparative Examples 1 to 4, the dispersion composition and the dispersion composition were prepared in the same manner as in Example 1 except that the type of the dispersant, the blending amount of the dispersant, and the type of the metal nanoparticles were changed. A coating film was prepared.

(Measurement of viscosity of dispersion composition immediately after preparation)
The dispersion composition obtained as described above was measured for viscosity immediately after preparation using an E-type viscometer (manufactured by Brookfield) at a rotation speed of 10 rpm and a measurement temperature of 20 ° C. The lower the viscosity, the better the dispersibility. Therefore, the dispersibility was evaluated according to the following criteria, and the results are shown in Table 2. A viscosity of less than 5.0 Pa · s was judged to have good dispersibility.
⊚: less than 4.0 Pa · s ○: 4.0 Pa · s or more and less than 4.5 Pa · s Δ: 4.5 Pa · s or more and less than 5.0 Pa · s ×: 5.0 Pa · s or more

(Stability of dispersion composition over time)
The dispersion composition obtained from the above was stored at 20 ° C. for 7 days, and measured using an E-type viscometer at a rotation speed of 10 rpm and a measurement temperature of 20 ° C. The stability over time was evaluated according to the following criteria using the increase in viscosity from immediately after preparation to 7 days after storage as an index, and the results are shown in Table 2. When the increase in viscosity was less than 2.0 Pa · s, it was judged that the dispersion stability was good.
⊚: Less than 0.5 Pa · s ○: 0.5 Pa · s or more and less than 1.0 Pa · s Δ: 1.0 Pa · s or more and less than 2.0 Pa · s ×: 2.0 Pa · s or more

(Evaluation of coating film smoothness)
The surface state of the coating film of the dispersion composition obtained above was observed with a laser microscope. Twelve images were acquired for each sample, and the average value of the maximum heights of the convex portions of each image was used as an index of smoothness. The smoothness was evaluated using the maximum height of the coating film of Comparative Example 1 as a reference value, and the results are shown in Table 2. When the maximum height of the convex portion of the coating film was less than 100% with respect to the reference value, it was judged that the smoothness was good.
⊚: Maximum height of the convex part of the coating film is less than 80% of the reference value ○: Maximum height of the convex part of the coating film is 80% or more and less than 90% of the standard value Δ: Convex part of the coating film Maximum height of 90% or more and less than 100% of the standard value ×: Maximum height of the convex portion of the coating film is 100% or more of the standard value

The dispersion compositions of Examples 1 to 10 using the dispersant of the present invention have a low viscosity immediately after preparation and suppress an increase in viscosity over time, and thus are excellent in dispersibility and dispersion stability. there were. This effect was the same in Example 11 in which the type of metal nanoparticles was changed. The coating film produced by using the dispersion compositions of Examples 1 to 11 has a lower maximum height of the convex portion as compared with Comparative Examples 1 and 2 using the amine-based dispersant and the polycarboxylic acid-based dispersant. , It had smoothness. In particular, the dispersion compositions of Examples 1, 5 and 6 were excellent in dispersibility, dispersion stability and smoothness of the prepared coating film. In Comparative Examples 1 and 2 using the amine-based dispersant and the polycarboxylic acid-based dispersant, the viscosity of the dispersion composition decreased, but the viscosity increased with time, and the dispersion stability was inferior. Further, in the dispersion compositions of Comparative Examples 3 and 4 using the dispersant into which only the monovalent carboxylic acid or the divalent carboxylic acid was introduced, the dispersibility was lowered, and the thickening with time was also observed, and the coating was applied. The smoothness of the membrane was also low.

Claims (3)

A dispersion composition containing a dispersant, metal nanoparticles, a non-aqueous solvent, and a binder resin.
The dispersant contains an ester compound of polyglycerin having an average degree of polymerization of 2 to 20 and at least one monovalent carboxylic acid and at least one divalent carboxylic acid or a derivative thereof. Dispersion composition. An ink, a paint, and a coating film obtained by using the dispersion composition according to claim 1. A molded product obtained by using any of the ink, paint, and coating film according to claim 2.