WO2023100504A1 - Paste for electronic components - Google Patents

Abstract

The present invention provides a paste for electronic components, the paste containing a binder that has the characteristics of a cellulose resin and the characteristics of a terminal functional group derived from a resin of another kind or a low-molecular weight material of another kind at the same time with good compatibility, and the paste enabling the achievement of a smooth coating film.　The present invention relates to a paste for electronic components, the paste containing inorganic particles, a dispersant, a binder and an organic solvent. With respect to this paste for electronic components, the binder contains, for example, at least a copolymer which is represented by general formula 1, wherein a first binding site at one end of the molecular chain of a cellulose resin is bonded to a resin of another kind or a low-molecular weight material of another kind by an ester bond or an amide bond.

Description

Paste for electronic parts

The present invention relates to a paste for electronic parts containing inorganic particles, a dispersant, a binder and an organic solvent, which is used in the manufacture of electronic parts, and particularly relates to improvement of the binder.

For example, with the increase in capacity and miniaturization of multilayer ceramic capacitors, there is a demand for multilayered and thinned dielectric sheets and internal electrode layers. In addition, good adhesiveness between the dielectric layer and the internal electrode layer, good printability of the internal electrode layer, high strength of the internal electrode layer, and the like are required.

Conventionally, cellulose-based resins have been used as binders in conductive pastes used to form internal electrode layers, but cellulose-based resins lack adhesion to acetal-based resins that are commonly used as binders in dielectric sheets. Therefore, there is a problem that delamination may occur.

Therefore, as described in Japanese Patent No. 5299904 (Patent Document 1), for example, by blending a cellulose-based resin and an acetal-based resin as a binder used in the conductive paste, the dielectric layers and the internal electrode layers are formed. or, as described in Japanese Patent No. 5224722 (Patent Document 2), for example, by blending a cellulose resin and an acetal resin, the adhesion between the dielectric layer and the internal electrode layer is improved. Techniques for improving the compatibility between the cellulose resin and the acetal resin and improving the storage stability while maintaining the effects of (1) have been proposed.

However, resin blends such as those described in Patent Documents 1 and 2 have relatively low compatibility. Therefore, for example, in the technique described in International Publication No. WO 2015/107811 (Patent Document 3), using the hydroxyl groups possessed by the cellulose resin and the acetal resin, using a binder crosslinked with a dicarboxylic acid-containing binder, It is intended to improve adhesion and compatibility.

Japanese Patent No. 5299904 Japanese Patent No. 5224722 WO2015/107811

In general, a polysaccharide solution containing many hydroxyl groups increases in viscosity and gels as the concentration of the polysaccharide increases. It is said that when the concentration of polysaccharide in a liquid increases, the polysaccharide molecules become entangled and partially bonded, forming a mesh-like network with that part as a starting point, and the entire solution becomes a gel.

In Patent Document 3, a low-reactivity portion remaining as a hydroxyl group in the cellulose-based resin is devised to make it easier to react with the acetal-based resin by using a binder having a lower molecular weight than that of the acetal-based resin. The base resin and the acetal resin are combined.

However, this also makes it easier to generate crosslinked products between cellulose-based resins and crosslinked products between acetal-based resins. In that case, a crosslinked material having a network structure is formed, and sometimes a crosslinked material having a huge ring structure may be formed. In particular, a crosslinked product composed only of a cellulose resin leads to gelation as in the above example, and if it is locally present in the electronic component paste, the smoothness of the coating film such as the internal electrode layer is impaired. put away.

The polymer adhesion phenomenon is greatly affected by the molecular structure of the polymer main chain and side chains, but it is speculated that the molecular structure of the polymer end is the next most influential factor. This is because the polymer has a very large molecular size and is entangled with each other, so it is difficult for the entire polymer to move during the adhesion process. This is because the molecular structure of the polymer terminal, which has a relatively high degree of freedom of movement, is thought to contribute to adhesion. Therefore, in addition to the method of bonding another kind of resin to the cellulose resin to improve the adhesion to the dielectric sheet, low-molecular hydrogen bonds, coordination bonds, and dipoles that contribute to the improvement of the adhesion to the ends of the cellulose resin can be used. A method of introducing a terminal functional group capable of interaction, acid-base interaction, etc. is also considered effective.

Therefore, the object of the present invention is to provide a smooth coating film in which the binder has both the characteristics of a cellulose resin and the characteristics of a terminal functional group derived from another type of resin or another type of low-molecular-weight polymer, and has good compatibility between the two. It is to provide a paste for electronic parts that can be obtained.

The present invention is directed to a paste for electronic parts containing inorganic particles, a dispersant, a binder and an organic solvent, wherein the binder is
(A) The first binding portion at one end of the molecular chain of the cellulose-based resin is connected to another type of resin or another type of low molecule via an ester bond or an amide bond. A copolymer represented by, or
(B) The first bond at one end of the molecular chain of the cellulose-based resin is an ester bond or an amide bond, and the second bond (X) and another type of resin are connected via the binder (R ₃ ). A copolymer represented by the general formula of the following chemical formula 3 or the general formula of the following chemical formula 4,
is characterized by including at least

In the formula, R ₁ represents hydrogen, an alkyl group, a hydroxyalkyl group or an acyl group, and R ₂ represents another kind of resin or alkyl group.

wherein R ₁ represents hydrogen, an alkyl group, a hydroxyalkyl group or an acyl group, R ₄ represents another type of resin, R ₃ represents an alkyl or sulfide-containing binder, and X represents an ester bond or an amide bond. indicates

According to the electronic component paste according to the present invention, the binder contained therein has both the characteristics of a cellulose resin and the characteristics of a terminal functional group derived from another type of resin or another type of low molecular weight resin, while at the same time Good compatibility can be achieved with different resins or different small molecules. In addition, since a resin that leads to gelation is less likely to form in the binder, it is possible to obtain an electronic component paste that does not impair the smoothness of the coating film.

FIG. 1 shows ¹ H-NMR spectra of ethyl cellulose derivatized products. FIG. 2 is a diagram showing the correlation between the molecular weight of ethyl cellulose determined by NMR and that determined by GPC.

The electronic component paste according to the present invention contains inorganic particles, a dispersant, a binder and an organic solvent. The binder is
(A) The first binding portion at one end of the molecular chain of the cellulose-based resin is connected to another type of resin or another type of low molecule via an ester bond or an amide bond. A copolymer represented by, or
(B) The first bond at one end of the molecular chain of the cellulose-based resin is an ester bond or an amide bond, and the second bond (X) and another type of resin are connected via the binder (R ₃ ). A copolymer represented by the general formula of Chemical Formula 7 below or the general formula of Chemical Formula 8 below,
including at least

In the formula, R ₁ represents hydrogen, an alkyl group, a hydroxyalkyl group or an acyl group, and R ₂ represents another kind of resin or alkyl group. The alkyl group for R ₂ preferably has 1 to 4 carbon atoms.

wherein R ₁ represents hydrogen, an alkyl group, a hydroxyalkyl group or an acyl group, R ₄ represents another type of resin, R ₃ represents an alkyl or sulfide-containing binder, and X represents an ester bond or an amide bond. indicates

The method of bonding the cellulose resin contained in the above-mentioned binder with another type of resin or another type of low-molecular-weight molecule may be by commonly used ester bond or amide bond reaction. There is a wide selection of materials as long as the molecule has a hydroxyl group or an amino group.

Therefore, in addition to the characteristics such as viscosity expression, elasticity, and printability possessed by cellulose resins, characteristics of terminal functional groups derived from different resins or other low molecules (for example, viscosity characteristics, other resins) If the cellulose resin is combined with another type of resin or another type of low molecule by the synthesis method described above, the properties of the cellulose type resin can be combined with another type of resin or another type of resin. It is possible to obtain a binder to which the properties of terminal functional groups derived from low molecular weight are added.

Also, when different types of resins are combined in the present invention, the compatibility between the cellulosic resin and the different type of resin can be improved. Furthermore, since one of the terminal carboxyl groups of the cellulose-based resin is used to bond with another type of resin, only a graft structure can be formed instead of a network structure as a bond between cellulose-based resins. Since the resin that leads to gelation is less likely to form, the smoothness of the coating film formed by the paste for electronic components according to the present invention is less likely to be impaired.

In the present invention, when an ester group or an amide group is introduced as a terminal functional group derived from a different type of low molecular weight, adhesion is improved by hydrogen bonding between the cellulose resin and the acetal resin, which is commonly used as a binder in dielectric sheets. be able to. In addition, since it does not exhibit peculiar behavior such as adsorption to powder, the smoothness of the paste coating film is also excellent.

In the above embodiment (B), the binder (R ₃ ) is an alkyl- or sulfide-containing binder. Does not generate a combined body with each other. Therefore, it is preferable not to use a vinyl group- or allyl group-introduced binder.

When different types of resins are combined in the present invention, by selecting the suitable conditions shown in the experimental examples described later, the blending ratio of the cellulose resin and the other type of resin, which tend to cause gelation between the cellulose resins, and the , Even under the reaction conditions using the binder (R ₃ ) of the above (B), only a graft structure can be formed, and a resin that leads to gelation is unlikely to be formed, so that the smoothness of the coating film is less likely to be impaired. can.

The cellulose resin is preferably cellulose ether having a carboxyl group at one end of the molecular chain. This is because it is more realistic to obtain a cellulose ether having a carboxyl group at one end of the molecular chain as the cellulose resin, considering the synthetic reaction scheme described later.

The cellulose ether is preferably alkyl cellulose.

A terminal functional group derived from a different type of resin and a different type of low-molecular-weight polymer, for example, is intended to compensate for properties not found in cellulose-based resins or to enhance the properties of cellulose-based resins.

Another type of resin is not particularly limited, and includes, for example, polyvinyl acetal-based resins, acrylic-based resins, polycarbonate-based resins, polyurethane-based resins, polyether-based resins, and polyester-based resins having hydroxyl groups or amino groups. Those containing at least one selected from the group are applied.

As another type of terminal functional group derived from a low molecular weight, an ester group or an amide group, which is relatively advantageous for hydrogen bonding and can improve adhesive strength, is applied.

The content ratio of the cellulose resin and the other resin is preferably in the range of 80:20 to 20:80 in terms of mass, more preferably in the range of 60:40 to 40:60 in terms of mass. By selecting such a ratio, the performance of both the cellulose-based resin and the resin of another type can be exhibited reliably.

The dispersant is not particularly limited, such as a general low-molecular one-end adsorption dispersant or a comb-shaped polymer dispersant, but a polycarboxylic acid-based dispersant is particularly preferred.

The inorganic particles contained in the electronic component paste according to the present invention preferably contain at least one of ceramic particles and metal particles. For example, a paste for forming dielectric layers in a multilayer ceramic capacitor contains at least ceramic particles, and a paste for forming internal electrode layers contains at least metal particles. The ceramic particles described above contain at least one element selected from, for example, Ba, Ti, Ca, Zr and Sr. The metal particles described above contain, for example, at least one metal selected from Cu, Ni, Au and Ag.

《Experiment example》
In this experimental example, 26 types of conductive pastes containing various binders were prepared as the paste for electronic parts, targeting conductive pastes for obtaining internal electrode layers of laminated ceramic capacitors.

Details of the 26 samples prepared in this experimental example are shown in Table 3 below. Including, "Comparative Examples" include binders that are simply blends of cellulosic resins and other resins.

A cellulose derivative with one terminal carboxyl group was synthesized as follows. Here, as a method for synthesizing a cellulose derivative having one terminal carboxyl group, a method for synthesizing ethyl cellulose, which is a kind of cellulose derivative and is widely used in pastes for electronic parts and the like, was adopted. In addition, the synthesis method is not particularly limited to the method shown below.

(1) Formation of one-end carboxylated cellulose by oxidation reaction of reducing terminal of cellulose A 50% sodium hydroxide aqueous solution (1680 g) was added to an aqueous dispersion slurry of cellulose (solid content: 1440 g). Then, sodium anthraquinone-2-sulfonate (24 g) dissolved in 30% hydrogen peroxide is added and stirred to oxidize the reducing end of the cellulose, followed by filtration and washing with water to obtain cellulose with one end carboxylated. rice field. This reaction is a reaction of oxidizing a formyl group having a formyl group by ring-opening to a carboxyl group among the tautomerisms of the reducing ends of cellulose.

Various methods are known for the oxidation reaction of the cellulose reducing terminal and the formyl group of the ring-opened sugar.

(2) Deprotonation reaction with sodium hydroxide A 50% sodium hydroxide aqueous solution was added to an aqueous solution of one-end carboxylated cellulose, and the mixture was stirred at 60°C for 20 minutes to convert the hydroxyl group to -ONa and one end to -COONa. Alkali cellulose was obtained.

(3) Ethoxylation (Etherification) Reaction and Ethyl Esterification Reaction with Ethyl Chloride Alkali cellulose and ethyl chloride were stirred at 110° C. for 12 hours in a pressure cooker at 0.5 MPa, and Ethyl cellulose whose ends were -COONa, -COOH or -COOEt was obtained. The ethoxylation degree of substitution (DS) for the three OH groups of the cellulose monomer units obtained at this time is in the range of 2.46 to 2.58 (ethoxylation degree 48.0 to 49.5% by mass). The amount of sodium hydroxide added and the amount of ethyl chloride added were adjusted so that

In addition, in this synthesis, the etherification reaction proceeds faster than the esterification reaction, so few -COOEt are esterified.

(4) Ester hydrolysis reaction One end of ethyl cellulose -COOEt -COOEt is hydrolyzed to -COOH, and the hydroxyl group is -OEt (substitution degree 2.5) and one end is -COONa. (carboxylate) or -COOH (carboxyl group) ethyl cellulose was obtained.

There are various hydrolysis reaction conditions, but the reaction proceeds by adding water to the alcohol solvent and heating it. A catalyst may be added for efficient reaction. Since esterification is difficult to proceed during the etherification reaction using ethyl chloride, ethyl cellulose in which most of the ends are -COONa (carboxylate) or -COOH (carboxyl group) at one end can be obtained without performing this step. Obtainable.

(5) Washing and drying After removing salts and by-products by washing with hot water, dry under reduced pressure to convert one end to -COONa (carboxylate) or -COOH (carboxyl group) and to the other end. A solid of one-end carboxylated ethyl cellulose having a substitution degree of ethoxylation of 2.5 was obtained, in which the was -OEt (ether). By adjusting the number average molecular weight of the cellulose initially used in the range of 10,000 to 100,000, the first single-end carboxylated ethyl cellulose (labeled "CC1" in Table 3) having a number average molecular weight Mn of 13,000, A second single-ended carboxylated ethyl cellulose having an average molecular weight Mn of 20,000, a third single-ended carboxylated ethyl cellulose having a number average molecular weight Mn of 54,000, and a fourth single-ended carboxylated ethyl cellulose having a number average molecular weight Mn of 88,000 (Table 3). 4 types of one-end carboxylated ethyl cellulose were able to be produced, as indicated by "CC4".

The number-average molecular weight was obtained by performing gel permeation chromatography (GPC) measurement using polystyrene as a standard polymer and tetrahydrofuran (THF) as an eluent.

(6) Quantification of Carboxyl Groups in One-End Carboxylated Ethylcellulose The amount of carboxyl groups in the one-end carboxylated ethyl cellulose synthesized as described above was quantified by ¹ H-NMR measurement. A trimethylsilyl (TMS) derivatization method was used because conventional NMR measurements were expected to lack sensitivity in quantifying terminal carboxyl groups, which are trace amounts.

The TMS derivatization method is a method of substituting a trimethylsilyl group (Si(CH ₃ ) ₃ ) for H of a hydroxyl group contained in a carboxyl group of ethyl cellulose. Due to this derivatization, the number of hydrogen atoms in the carboxyl group is changed from 1H to 9H, so the detection sensitivity in ¹ H-NMR is increased ninefold.

A derivatized product is obtained by adding ethyl cellulose and a derivatizing reagent (BSTFA) to a dehydrated chloroform solvent and heating at 70° C. for 1 hour. Since the derivatization reagent acts on both hydroxyl groups and carboxyl groups of ethyl cellulose, the amount of reagent to be added was about 1.5 times the molar number of hydroxyl groups and terminal carboxyl groups of ethyl cellulose. In addition, it was confirmed that the quantitative values of TMS hydroxyl groups and carboxyl groups did not change even when the amount of the reagent was added in excess of 1.5 times the molar amount. After the solution after the reaction was returned to room temperature and vacuum-dried, the solvent and unreacted derivatization reagent were removed to obtain a dried derivatized product by preparative GPC. This dried product was redissolved in deuterated chloroform, which is a solvent for NMR measurement, and ¹ H-NMR measurement was performed. A ¹ H-NMR spectrum of the ethyl cellulose derivatized product is shown in FIG.

In the ¹ H-NMR spectrum of the ethyl cellulose derivatized product, a peak derived from the derivatization of the carboxyl group is detected at 0.3 ppm indicated by the arrow in FIG. The concentration of carboxyl groups in ethyl cellulose was obtained by calculating the respective molar ratios from the peak area ratios of the cellulose skeleton, ethoxy groups, carboxyl groups, and hydroxyl groups observed by ¹ H-NMR. Table 1 shows the quantification results of carboxyl groups and the average molecular weights of the corresponding samples. GPC was measured under THF solvent, and the number average molecular weight was determined in terms of polystyrene.

The number of carboxyl groups in ethyl cellulose decreases as the molecular weight increases, suggesting that the carboxyl groups are present in sites that depend on the molecular weight. Since the terminal concentration of the polymer decreases as the molecular weight of one molecular chain increases, it is considered that the quantified carboxyl groups are present at the terminal. From the aspect of the synthesis reaction scheme of the sample, it can be determined that the carboxyl group analyzed by NMR exists at one end.

Furthermore, assuming that the carboxyl group quantified by NMR exists at one end of ethyl cellulose, the molecular weight of ethyl cellulose was calculated by determining the number of repetitions of ethyl cellulose. Table 2 shows the average molecular weight determined by NMR and the average molecular weight determined by GPC.

Since the average molecular weight determined by GPC is in terms of polystyrene, the average molecular weight determined by NMR does not match the average molecular weight determined by GPC in absolute value. On the other hand, as shown in FIG. 2, when the molecular weight values obtained by both methods were compared for samples with different molecular weights, a high correlation was shown. This result indicates that a carboxyl group exists at one end of ethyl cellulose, and it can be said that NMR quantified the carboxyl group present at one end.

Next, the cellulose derivative having a one-end carboxyl group obtained as described above (each of the first to fourth one-end carboxylated ethyl cellulose) and another kind of resin are connected, the implementation shown in Table 3 Copolymers were synthesized for each of Examples 1-14.

[Example 1]
(Synthesis of first copolymer of one-end carboxylated ethyl cellulose and polyvinyl acetal-based resin)
5 parts by mass of the first one-end carboxylated ethyl cellulose as a cellulose derivative having a one-end carboxyl group, and a polyvinyl acetal resin having a hydroxyl group as another resin ("BL-S" manufactured by Sekisui Chemical Co., Ltd., number average 5 parts by mass of molecular weight Mn = 27000) was dried under reduced pressure, 90 parts by mass of ethyl acetate was added, and dissolved at 50°C in a nitrogen atmosphere. To the resulting solution, diisopropylcarbodiimide as a condensing agent was added in an amount 1.1 times the molar amount of the first one-end carboxylated ethyl cellulose, and dimethylaminopyridine as a reaction accelerator was added in an amount 0.01 times the molar amount of the condensing agent. A molar amount was added and the reaction was carried out by stirring at a temperature of 50° C. for 24 hours to prepare a binder solution. After that, ethyl acetate was distilled off to obtain a solid copolymer formed by an ester bond between a cellulose derivative having one terminal carboxyl group and a polyvinyl acetal-based resin.

Analysis of the resulting copolymer by FT-IR (Fourier transform infrared spectroscopy) and ¹ H-NMR confirmed the formation of ester bonds. , the progress of the reaction could be confirmed.

After that, in order to prepare a conductive paste, 10 parts by mass of the obtained copolymer was dissolved in 90 parts by mass of dihydroterpinyl acetate to prepare a binder solution.

[Example 2]
(Synthesis of fourth one-end carboxylated ethyl cellulose and polyvinyl acetal-based resin copolymer)
The cellulose derivative having one terminal carboxyl group was changed to the fourth one terminal carboxylated ethyl cellulose, and another type of resin was replaced with a polyvinyl acetal resin having a hydroxyl group ("BH-S" manufactured by Sekisui Chemical Co., Ltd., number average molecular weight Mn = 63000), the reaction was carried out under the same conditions as in Example 1 to prepare a binder solution containing a copolymer formed by ester bonding of a cellulose derivative having one terminal carboxyl group and a polyvinyl acetal resin.

[Example 3]
(Synthesis of first copolymer of one-end carboxylated ethyl cellulose and polyvinyl acetal-based resin)
Reaction was performed under the same conditions as in Example 1, except that the different resin was changed to a polyvinyl acetal resin having a hydroxyl group (“BH-S” manufactured by Sekisui Chemical Co., Ltd., number average molecular weight Mn = 63000). A binder solution containing a copolymer formed by an ester bond between a cellulose derivative having a terminal carboxyl group and a polyvinyl acetal resin was prepared.

[Example 4]
(Synthesis of fourth one-end carboxylated ethyl cellulose and polyvinyl acetal-based resin copolymer)
The cellulose derivative having one terminal carboxyl group was reacted under the same conditions as in Example 1 except that the cellulose derivative having one terminal carboxyl group was changed to the fourth one-terminal carboxylated ethyl cellulose, and the cellulose derivative having one terminal carboxyl group and the polyvinyl acetal resin were reacted. A binder solution containing a copolymer with an ester bond was prepared.

[Example 5]
(Synthesis of first copolymer of one-end carboxylated ethyl cellulose and acrylic resin)
Example except that another type of resin was changed to an acrylic resin having a hydroxyl group (main monomer is isobutyl methacrylate, acrylic resin containing 5 mol% of 2-hydroxyethyl methacrylate, number average molecular weight Mn = 21000) A binder solution containing a copolymer formed by an ester bond between a cellulose derivative having a carboxyl group at one end and an acrylic resin was prepared.

[Example 6]
(Synthesis of first copolymer of one-end carboxylated ethyl cellulose and aliphatic polycarbonate resin)
A cellulose derivative having one terminal carboxyl group was reacted under the same conditions as in Example 1, except that the different resin was changed to an aliphatic polycarbonate resin having a hydroxyl group (polypropylene carbonate, number average molecular weight Mn = 24000). A binder solution containing a copolymer formed by an ester bond between a polystyrene resin and a polycarbonate resin was prepared.

[Example 7]
(Synthesis of first copolymer of one-end carboxylated ethyl cellulose and polyurethane resin)
Different types of resins are polyurethane resins with hydroxyl groups (polyester polyol PMPA (poly(3-methyl 1,5-pentanediol adipate) diol), polyether polyol PPG (poly(propylene glycol) diol) and diisocyanate IPDI (isophorone). diisocyanate), IPDI (isophoronediamine) and DETA (diethylenetriamine) as chain extenders, ethanolamine as a terminator, and the number average molecular weight Mn = 24000). A binder solution containing a copolymer formed by an ester bond between a cellulose derivative having a carboxyl group at one end and a polyurethane resin was prepared.

[Example 8]
(Synthesis of first copolymer of one-end carboxylated ethyl cellulose and polyurethane resin)
Different types of resins are polyurethane resins having amino groups (polyester polyol PMPA (poly(3-methyl 1,5-pentanediol adipate) diol), polyether polyol PPG (poly(propylene glycol) diol) and diisocyanate IPDI ( IPDI (isophoronediamine) and DETA (diethylenetriamine) as chain extenders, ethylenediamine as a terminator, and number average molecular weight (Mn = 26000) were added to the prepolymer consisting of isophorone diisocyanate). to prepare a binder solution containing a copolymer formed by an amide bond between a cellulose derivative having one terminal carboxyl group and a polyurethane resin.

[Example 9]
(Synthesis of first copolymer of one-end carboxylated ethyl cellulose and polyether resin)
A cellulose derivative having one terminal carboxyl group and poly A binder solution containing a copolymer formed by ester bonding with an ether-based resin was prepared.

[Example 10]
(Synthesis of fourth one-end carboxylated ethyl cellulose and aliphatic polyester resin copolymer)
A cellulose derivative having one terminal carboxyl group was reacted under the same conditions as in Example 2, except that the different resin was changed to an aliphatic polyester resin having a hydroxyl group (polycaprolactone, number average molecular weight Mn = 45000). A binder solution was prepared containing a copolymer formed by ester bonding of a polyester-based resin and a polyester-based resin.

In Examples 11 to 14 below, the content ratio of the cellulose derivative having one terminal carboxyl group and another resin was changed to several ratios different from 50:50.

[Example 11]
(Synthesis of first copolymer of one-end carboxylated ethyl cellulose and polyvinyl acetal-based resin)
6 parts by mass of the first one-end carboxylated ethyl cellulose as a cellulose derivative having a one-end carboxyl group, another type of resin, a polyvinyl acetal resin having a hydroxyl group ("BL-S" manufactured by Sekisui Chemical Co., Ltd., number average Molecular weight Mn = 27,000), except that the content was changed to 4 parts by mass. A binder solution was prepared.

[Example 12]
(Synthesis of first copolymer of one-end carboxylated ethyl cellulose and polyvinyl acetal-based resin)
8 parts by mass of the first one-end carboxylated ethyl cellulose as a cellulose derivative having a one-end carboxyl group, another type of resin, a polyvinyl acetal resin having a hydroxyl group ("BL-S" manufactured by Sekisui Chemical Co., Ltd., number average Molecular weight Mn = 27000), except that the content was changed to 2 parts by mass. A binder solution was prepared.

[Example 13]
(Synthesis of first copolymer of one-end carboxylated ethyl cellulose and polyvinyl acetal-based resin)
4 parts by mass of the first one-end carboxylated ethyl cellulose as a cellulose derivative having a one-end carboxyl group, another type of resin, a polyvinyl acetal resin having a hydroxyl group ("BL-S" manufactured by Sekisui Chemical Co., Ltd., number average Molecular weight Mn = 27,000), except that the content was changed to 6 parts by mass. A binder solution was prepared.

[Example 14]
(Synthesis of first copolymer of one-end carboxylated ethyl cellulose and polyvinyl acetal-based resin)
2 parts by mass of the first one-end carboxylated ethyl cellulose as a cellulose derivative having a one-end carboxyl group, another type of resin, a polyvinyl acetal resin having a hydroxyl group ("BL-S" manufactured by Sekisui Chemical Co., Ltd., number average Molecular weight Mn = 27,000), except that the content was changed to 8 parts by mass. A binder solution was prepared.

Next, as Comparative Examples 1 to 10, binder solutions were obtained in which a cellulose derivative having a carboxyl group at one end and another type of resin were simply mixed. It should be noted that Comparative Examples 1 to 10 share a different resin from Examples 1 to 10, respectively.

[Comparative Example 1]
(Preparation of mixture of first one-end carboxylated ethyl cellulose and polyvinyl acetal-based resin)
5 parts by mass of the first one-end carboxylated ethyl cellulose as a cellulose derivative having a one-end carboxyl group, and a polyvinyl acetal resin having a hydroxyl group as another resin ("BL-S" manufactured by Sekisui Chemical Co., Ltd., number average 5 parts by mass of molecular weight Mn=27000) was dissolved in 90 parts by mass of dihydroterpinyl acetate to prepare a binder solution.

[Comparative Example 2]
(Preparation of mixture of fourth one-end carboxylated ethyl cellulose and polyvinyl acetal-based resin)
The cellulose derivative having one terminal carboxyl group was changed to the fourth one terminal carboxylated ethyl cellulose, and another type of resin was replaced with a polyvinyl acetal resin having a hydroxyl group ("BH-S" manufactured by Sekisui Chemical Co., Ltd., number average molecular weight A binder solution was prepared under the same conditions as in Comparative Example 1, except that Mn was changed to 63000).

[Comparative Example 3]
(Preparation of mixture of first one-end carboxylated ethyl cellulose and polyvinyl acetal-based resin)
A binder solution was prepared under the same conditions as in Comparative Example 1, except that the different resin was changed to a polyvinyl acetal resin having hydroxyl groups ("BH-S" manufactured by Sekisui Chemical Co., Ltd., number average molecular weight Mn = 63000). bottom.

[Comparative Example 4]
(Preparation of mixture of fourth one-end carboxylated ethyl cellulose and polyvinyl acetal-based resin)
A binder solution was prepared under the same conditions as in Comparative Example 1, except that the cellulose derivative having a one-end carboxyl group was changed to the fourth one-end carboxylated ethyl cellulose.

[Comparative Example 5]
(Preparation of mixture of first one-end carboxylated ethyl cellulose and acrylic resin)
A comparative example except that another resin was changed to an acrylic resin having a hydroxyl group (main monomer is isobutyl methacrylate, acrylic resin containing 5 mol% of 2-hydroxyethyl methacrylate, number average molecular weight Mn = 21000) A binder solution was prepared under the same conditions as in 1.

[Comparative Example 6]
(Preparation of mixture of first one-end carboxylated ethyl cellulose and aliphatic polycarbonate resin)
A binder solution was prepared under the same conditions as in Comparative Example 1, except that an aliphatic polycarbonate resin (polypropylene carbonate, number average molecular weight Mn=24000) having hydroxyl groups was used instead of another resin.

[Comparative Example 7]
(Preparation of mixture of first one-end carboxylated ethyl cellulose and polyurethane resin)
Different types of resins are polyurethane resins with hydroxyl groups (polyester polyol PMPA (poly(3-methyl 1,5-pentanediol adipate) diol), polyether polyol PPG (poly(propylene glycol) diol) and diisocyanate IPDI (isophorone). diisocyanate), IPDI (isophoronediamine) and DETA (diethylenetriamine) as chain extenders, ethanolamine as a terminator, and the number average molecular weight Mn = 24000). A binder solution was prepared under the conditions.

[Comparative Example 8]
(Preparation of mixture of first one-end carboxylated ethyl cellulose and polyurethane resin)
Different types of resins are polyurethane resins having amino groups (polyester polyol PMPA (poly(3-methyl 1,5-pentanediol adipate) diol), polyether polyol PPG (poly(propylene glycol) diol) and diisocyanate IPDI ( IPDI (isophoronediamine) and DETA (diethylenetriamine) as chain extenders, ethylenediamine as a terminator, and number average molecular weight (Mn = 26000) were added to the prepolymer consisting of isophorone diisocyanate). A binder solution was prepared under the conditions of

[Comparative Example 9]
(Preparation of mixture of first one-end carboxylated ethyl cellulose and polyether resin)
A binder solution was prepared under the same conditions as in Comparative Example 1, except that the different resin was changed to a polyether resin (mPEG, number average molecular weight Mn=10000) having hydroxyl groups.

[Comparative Example 10]
(Preparation of mixture of fourth one-end carboxylated ethyl cellulose and aliphatic polyester resin)
A binder solution was prepared under the same conditions as in Comparative Example 2, except that the other type of resin was changed to an aliphatic polyester resin having hydroxyl groups (polycaprolactone, number average molecular weight Mn=45000).

Synthesis Examples 1 to 3 below are copolymers in which a cellulose derivative having a carboxyl group at one end and another type of resin are linked via a binder.

<Synthesis Example 1>
(Synthesis of cellulose derivative in which allyl alcohol is introduced into the first one-end carboxylated ethyl cellulose)
10 parts by mass of the first one-end carboxylated ethyl cellulose was dried under reduced pressure, 90 parts by mass of ethyl acetate was added, and dissolved at 50° C. in a nitrogen atmosphere. To the resulting solution, 0.045 parts by mass of allyl alcohol, diisopropylcarbodiimide as a condensing agent, 1.1 times the molar amount of the cellulose derivative having one terminal carboxyl group, and dimethylaminopyridine as a reaction accelerator are condensed. A binder solution was prepared by adding 0.01 times the number of moles of the agent and reacting by stirring at a temperature of 50° C. for 24 hours.

After that, by distilling off the ethyl acetate, a cellulose derivative according to Synthesis Example 1 was produced as a solid, in which allyl alcohol was introduced into the cellulose derivative having one terminal carboxyl group.

The obtained cellulose derivative according to Synthesis Example 1 was analyzed by FT-IR and ¹ H-NMR, and the formation of ester bonds and allyl groups derived from allyl alcohol was confirmed, confirming the progress of the reaction.

<Synthesis Example 2>
(Synthesis of polyvinyl acetal-based resin derivative in which methacrylic acid is introduced into polyvinyl acetal-based resin having hydroxyl group)
As another type of resin, 10 parts by mass of a polyvinyl acetal-based resin ("BL-S" manufactured by Sekisui Chemical Co., Ltd., number average molecular weight Mn = 27000) having a hydroxyl group is dried under reduced pressure, 90 parts by mass of ethyl acetate is added, and a nitrogen atmosphere is added. and melted at 50°C. To the obtained solution, 0.032 parts by mass of methacrylic acid, diisopropylcarbodiimide as a condensing agent, 1.1 times the molar amount of the polyvinyl acetal resin having a hydroxyl group, and dimethylaminopyridine as a reaction accelerator. An amount of 0.01 times the number of moles of the condensing agent was added, and reaction was carried out by stirring at a temperature of 50° C. for 24 hours to prepare a binder solution.

After that, by distilling off the ethyl acetate, a polyvinyl acetal-based resin derivative according to Synthesis Example 2, in which methacrylic acid was introduced into a polyvinyl acetal-based resin having hydroxyl groups, was obtained as a solid.

When the obtained polyvinyl acetal-based resin derivative according to Synthesis Example 2 was analyzed by FT-IR and ¹ H-NMR, the formation of an ester bond and a vinyl group derived from methacrylic acid was confirmed, confirming the progress of the reaction. did it.

<Synthesis Example 3>
(Synthesis of Polyvinyl Acetal Resin Derivative in which Thioglycolic Acid is Introduced into Polyvinyl Acetal Resin Having Hydroxyl Groups)
As another type of resin, 10 parts by mass of a polyvinyl acetal-based resin ("BL-S" manufactured by Sekisui Chemical Co., Ltd., number average molecular weight Mn = 27000) having a hydroxyl group is dried under reduced pressure, 90 parts by mass of ethyl acetate is added, and a nitrogen atmosphere is added. and melted at 50°C. To the resulting solution, 0.034 parts by mass of thioglycolic acid, diisopropylcarbodiimide as a condensing agent, 1.1 times the molar amount of the polyvinyl acetal resin having a hydroxyl group, and dimethylaminopyridine as a reaction accelerator. was added in an amount 0.01 times the number of moles of the condensing agent, and the mixture was stirred at a temperature of 50° C. for 24 hours for reaction to prepare a binder solution.

After that, ethyl acetate was distilled off to obtain a polyvinyl acetal-based resin derivative according to Synthesis Example 3, in which thioglycolic acid was introduced into a polyvinyl acetal-based resin having hydroxyl groups, as a solid.

When the obtained polyvinyl acetal-based resin derivative according to Synthesis Example 3 was analyzed by FT-IR and ¹ H-NMR, an ester bond was confirmed and the progress of the reaction was confirmed.

Next, by combining the resin derivatives according to Synthesis Examples 1 to 3, copolymers according to Examples 15 and 16 were synthesized.

[Example 15]
(Synthesis of Copolymer of Cellulose Derivative Introduced with Allyl Alcohol and Polyvinyl Acetal Resin Derivative Introduced with Methacrylic Acid)
5 parts by mass of the cellulose derivative into which allyl alcohol according to Synthesis Example 1 has been introduced and 5 parts by mass of the polyvinyl acetal resin derivative into which methacrylic acid according to Synthesis Example 2 has been introduced as a different resin are dried under reduced pressure, 90 parts by mass of dihydroterpinyl acetate was added thereto and dissolved at 50° C. under a nitrogen atmosphere. Next, 0.05 part by mass of azobisisobutyronitrile as a polymerization initiator was added to this solution, and the reaction was carried out at 80° C. for 5 hours to obtain the allyl alcohol-introduced cellulose derivative according to Synthesis Example 1. and the polyvinyl acetal resin derivative according to Synthesis Example 2 were prepared.

For analysis of the resulting copolymer, the binder solution was poured into methanol to precipitate the binder and dried under reduced pressure to obtain the copolymer as a solid.

When the obtained copolymer was analyzed by FT-IR and ¹ H-NMR, it was confirmed that allyl groups and vinyl groups had disappeared. The progress of the reaction was confirmed.

[Example 16]
(Synthesis of Copolymer of Cellulose Derivative Introduced with Allyl Alcohol and Polyvinyl Acetal Resin Derivative Introduced with Thioglycolic Acid)
A binder solution containing a copolymer was prepared by reacting under the same conditions as in Example 15 except that the different resin was changed to the polyvinyl acetal resin derivative into which thioglycolic acid was introduced according to Synthesis Example 3. A copolymer of the allyl alcohol-introduced cellulose derivative of Synthesis Example 1 and the polyvinyl acetal resin derivative of Synthesis Example 3 was obtained from this binder solution.

When the obtained copolymer was analyzed by FT-IR and ¹ H-NMR, it was confirmed that allyl groups had disappeared. could be confirmed.

[Example 17]
(Preparation of binder resin in which a terminal functional group derived from a different low molecular weight is introduced into a cellulose derivative having one terminal carboxyl group)
10 parts by mass of the fourth one-end carboxylated ethyl cellulose as a cellulose derivative having a one-end carboxyl group was dried under reduced pressure, 90 parts by mass of ethyl acetate was added, and dissolved at 50° C. under a nitrogen atmosphere. To the resulting solution, ethanol was added in an amount 5 times the molar amount of the fourth one-end carboxylated ethyl cellulose, diisopropylcarbodiimide as a condensing agent was added in an amount 5 times the molar amount, and dimethylaminopyridine was added as a reaction accelerator to the molar amount of the condensing agent. A 0.01-fold molar amount was added and reacted by stirring at a temperature of 50° C. for 24 hours to prepare a binder solution.

After that, ethyl acetate and ethanol were distilled off to obtain a solid binder resin in which a terminal functional group was introduced into a cellulose derivative having one terminal carboxyl group.

When the obtained binder resin was analyzed by FT-IR and ¹ H-NMR, formation of an ester bond was confirmed, and GPC analysis showed that the number average molecular weight was larger than that of the raw material resin, indicating that the reaction progressed. It could be confirmed.

After that, in order to prepare a conductive paste, 10 parts by mass of the obtained binder resin was dissolved in 90 parts by mass of dihydroterpinyl acetate to prepare a binder solution.

[Preparation of conductive paste]
44.0 parts by mass of nickel powder with a BET diameter of 177 nm (SSA (specific surface area) = 3.8 m ² /g) and ceramic powder mainly composed of barium titanate with a BET diameter of 13 nm (SSA = 77 m ² /g) 2.9 parts by mass, 0.7 parts by mass of a polycarboxylic acid polymer dispersant, 21.2 parts by mass of the binder solutions obtained in the above examples and comparative examples, and 31 parts by mass of dihydroterpineol acetate .2 parts by mass were mixed and dispersed by a three-roll mill to prepare a conductive paste.

The dispersion method is not limited to the above method, and various methods such as roll mill, ball mill, bead mill, and high-pressure dispersion can be applied.

[Evaluation of Resin Component in Paste]
The conductive paste containing the binder solution according to Example 1 and prepared as described above was treated with a centrifuge (manufactured by Hitachi Koki "CS100FNX", rotation speed 29000 rpm, 20 minutes) to separate nickel particles and ceramic particles. It was allowed to settle and the supernatant was collected. After separating the polymer component by GPC (gel permeation chromatography), when the polymer component was processed by HPLC (high performance liquid chromatograph), a peak corresponding to ethyl cellulose and a peak corresponding to PVB (polyvinyl butyral) were observed. It was confirmed that there is also a peak in between. From this, it was found that the synthesis of the copolymer was successful.

In addition, when the dried solid content of the supernatant obtained by drying the polymer component fractionated by GPC was converted to TMS (trimethylsilyl) and subjected to NMR measurement, ^{no 1} H-NMR peak derived from the carboxyl group was confirmed.

In addition, the dried solid content of the dried supernatant was reacted with sodium hydroxide in a water-methanol mixed solvent to carry out heat hydrolysis. After separating the polymer component by GPC, the cellulose resin was separated from the polymer component by HPLC ^, the dried solid content was converted to TMS, and NMR measurement was performed. peak was confirmed.

From these, it was confirmed that the binder according to Example 1, which was synthesized from the first one-end carboxylated ethyl cellulose and polyvinyl acetal-based resin, was present in the paste. Moreover, it was confirmed that the binder according to Example 1, which was synthesized from the first one-end carboxylated ethyl cellulose and polyvinyl acetal-based resin, was not deteriorated in the paste.

[Evaluation of smoothness of electrode coating film]
The smoothness of the electrode coating film was evaluated by performing the following operations on the produced conductive paste.

A conductive paste as a sample was applied on a glass substrate with a 9 μm doctor blade, and the smoothness of the electrode coating film after heat drying was evaluated using a hybrid laser microscope (OPTELICS) manufactured by Lasertec Co., Ltd. The measurement conditions for the hybrid laser microscope were: measurement mode: surface shape, magnification: 50 times, resolution in height direction: 0.04 μm, measurement area: 1.44 mm ² .

If the compatibility between the cellulose derivative and another type of resin is low, aggregates are formed, and if the degree of cross-linking is high, gelled products are formed. However, these products are not major components and are assumed to occur infrequently. Therefore, Sz (in-plane distribution of maximum height), which is the sum of Sp (in-plane distribution of maximum peak height) and Sv (in-plane distribution of maximum valley depth) in the electrode coating film, was determined. Smoothness was evaluated according to the following criteria for the average value after 16-point measurement.
A: The Sz value is less than 1.80 µm.
Good: The Sz value is 1.80 or more and less than 1.90 µm.
x: The Sz value is 1.90 μm or more.

Table 3 summarizes the number average molecular weights Mn of the copolymers according to Examples and Comparative Examples and the evaluation results of smoothness.

From the results of Examples 1 to 16 in Table 3, the conductive paste contains a binder in which a carboxyl group at one end of the molecular chain of the cellulose resin and another type of resin are combined, so that the cellulose resin and It was confirmed that the compatibility with other resins was improved and the smoothness of the coating film was not impaired. In addition, this effect can be obtained by using, for example, alkyl cellulose as a cellulose resin, and other resins having hydroxyl groups or amino groups, such as polyvinyl acetal resins, acrylic resins, polycarbonate resins, polyurethane resins, and polyether resins. It can be obtained by using either the resin or the polyester resin, and the content ratio of the cellulosic resin and the other resin is surely obtained in the range of 80:20 to 20:80 in terms of mass.

From Example 17 in Table 3, it was confirmed that the smoothness of the coating film was not impaired when the conductive paste contained a cellulose-based resin having an ester group as the functional group at one end of the molecular chain.

Examples of conductive pastes containing nickel particles as metal particles have been described above. and ceramic particles such as BaTiO ₃ particles, similar effects can be obtained. From this, it can be seen that the inorganic particles contained in the electronic component paste may be any inorganic particles.

Claims (11)

including inorganic particles, a dispersant, a binder and an organic solvent,
The binder is
(A) The first binding portion at one end of the molecular chain of the cellulose-based resin is connected to another type of resin or another type of low molecule via an ester bond or an amide bond. A copolymer represented by, or
(B) The first bond at one end of the molecular chain of the cellulose-based resin is an ester bond or an amide bond, and the second bond (X) and another type of resin are connected via the binder (R ₃ ). A copolymer represented by the general formula of the following chemical formula 3 or the general formula of the following chemical formula 4,
An electronic component paste comprising at least:

In the formula, R ₁ represents hydrogen, an alkyl group, a hydroxyalkyl group or an acyl group, and R ₂ represents another kind of resin or alkyl group.

wherein R ₁ represents hydrogen, an alkyl group, a hydroxyalkyl group or an acyl group, R ₄ represents another type of resin, R ₃ represents an alkyl or sulfide-containing binder, and X represents an ester bond or an amide bond. indicates The electronic component paste according to claim 1, wherein the cellulose resin is a cellulose ether having a carboxyl group at one end of the molecular chain. The electronic component paste according to claim 2, wherein the cellulose ether is an alkyl cellulose. Said another type of resin includes at least one selected from the group consisting of polyvinyl acetal resins having hydroxyl groups or amino groups, acrylic resins, polycarbonate resins, polyurethane resins, polyether resins and polyester resins. Item 4. The electronic component paste according to any one of Items 1 to 3. The electronic component paste according to claim 1, wherein the content ratio of the cellulose resin and the different resin is in the range of 80:20 to 20:80 in terms of mass. The electronic component paste according to any one of claims 1 to 5, wherein the inorganic particles include at least one of ceramic particles and metal particles. The electronic component paste according to claim 6, wherein the ceramic particles contain at least one element selected from Ba, Ti, Ca, Zr and Sr. 7. The electronic component paste according to claim 6, wherein said metal particles contain at least one metal selected from Cu, Ni, Au and Ag. The electronic component paste according to any one of claims 1 to 8, wherein the dispersant is a polymer dispersant. The electronic component paste according to claim 9, wherein the polymer dispersant is a polycarboxylic acid-based dispersant. 11. The electronic component paste according to claim 1, wherein the alkyl group for R ₂ has 1 to 4 carbon atoms.

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