JPH06206760A - Binder for molding ceramic green sheet for laminated electric part - Google Patents

Abstract

PURPOSE:To obtain a binder for forming the ceramic green sheet, comprising a resin blend as a main component obtained by modifying a mixture of polyvinyl butyral resin and a methacrylic acid ester-based resin with ethylene carbonate. CONSTITUTION:This binder comprises a resin blend obtained by modifying a mixture of a polyvinyl butyral resin and a methacrylic acid ester-based resin as a main component with ethylene carbonate. This binder is used as a binder for forming a ceramic green sheet for laminated electronic parts to give an excellent green sheet without being affected by chemical state of raw material powder of electronic ceramic and a solvent of electrode paste.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a binder used for forming a ceramic green sheet for laminated electronic parts.

[0002]

2. Description of the Related Art Generally, in a manufacturing process of a multilayer electronic component, for example, a multilayer ceramic capacitor, a polyvinyl butyral resin, a methacrylic ester resin, polyvinyl alcohol, vinyl acetate resin, or the like is used as a binder, and an electronic ceramic is used for the binder. After the material powder is mixed and dispersed to prepare a slurry, this is formed into a sheet by a doctor blade method or a dip pulling method to obtain a ceramic green sheet, and an internal electrode paste is printed on the surface thereof. There is. This internal electrode paste usually contains a resin and an organic solvent, and as the solvent, an organic solvent compatible with the binder for the ceramic green sheet is adopted. For example, in the case of a ceramic green sheet using a polyvinyl butyral resin as a binder, terpineol is generally used as the solvent.

As a means for adding an additive element for controlling the characteristics of the electronic ceramic material, the additive element is in the form of a compound soluble in an organic solvent, for example, a metal soap, an alkoxide or an acetylacetonate compound. In many cases, a method of adding to and fixing to the surface of the powder particles is added.

[0004]

However, an electrode paste using terpineol as a solvent gives good results when printed on the surface of a ceramic green sheet using a polyvinyl butyral resin as a binder, but a methacrylic ester resin is used. When printing on the surface of the ceramic green sheet used as the binder, the solubility parameter of terpineol (hereinafter referred to as SP) and the SP of the methacrylic ester resin are close, so the green sheet is affected by terpineol and the back of the green sheet is affected. There is a problem that the electrode paste permeates or wrinkles occur in the green sheet when dried after printing, and the chip obtained by firing this does not function as a capacitor.

On the other hand, when a ceramic green sheet is prepared by using a polyvinyl butyral resin as a binder resin in an electronic ceramic material to which a metal soap is added, a hydrophilic and highly active OH group is present in the molecule of the polyvinyl butyral resin, so that a slurry is obtained. When converted, the OH group of the polyvinyl butyral resin reacts with the carboxylic acid group in the metal soap and the alkoxy group in the alkoxide to cause a gelation reaction of the polyvinyl butyral resin, which causes a problem that a sheet cannot be formed.

As described above, in the conventional method, the quality or characteristics of the ceramic green sheet or the electronic component is significantly influenced by the combination of the binder resin of the green sheet and the solvent of the internal electrode paste or the raw material powder of the electronic ceramic material. Therefore, not only the selection of the binder resin but also the selection of the solvent for the electrode paste is limited, unless the binder resin is necessarily prepared according to the electronic ceramic material powder or various electrode pastes are prepared according to the binder resin. In the case of high-mix low-volume production, it was extremely uneconomical.

Therefore, an object of the present invention is to make it possible to form a good ceramic green sheet without being affected by the chemical form of the raw material powder of electronic ceramics or the solvent of the electrode paste.

[0008]

Means for Solving the Problems The present invention provides, as a means for solving the above problems, a composite resin containing a polyvinyl butyral resin and a methacrylic acid ester-based resin as main components, which are modified with ethylene carbonate. It is intended to be used as a binder for forming a ceramic green sheet for laminated electronic parts.

As the polyvinyl butyral resin, those generally used as a binder may be used, but as a typical polyvinyl butyral resin, vinyl butyral 60 to 75% by weight and vinyl alcohol 10 are used.
˜35% by weight and 5 to 30% by weight of vinyl acetate are included. Incidentally, the polyvinyl butyral resin shows that when the proportion of vinyl butyral which is a raw material monomer thereof increases, the solubility, compatibility, water resistance and softening property tend to improve, and when the proportion of vinyl acetate increases, the solubility increases. Further, when the water resistance is improved and the proportion of vinyl alcohol is further increased, water solubility and hydrophilicity tend to be increased, but from the viewpoint of various properties as a binder resin, those having the above composition range are preferable.

Typical examples of the methacrylic acid ester resin include polymethacrylic acid methyl ester, polymethacrylic acid ethyl ester, polymethacrylic acid i-propyl ester, and polymethacrylic acid sec-butyl ester. Alternatively, an alkyl methacrylic acid resin in which the H group of methacrylic acid is substituted with an alkyl group may be used.

Further, commercially available ethylene carbonate may be used for modifying the polyvinyl butyral resin and the methacrylic acid ester resin.

The polyvinyl butyral resin, the methacrylic acid ester resin and the ethylene carbonate can be blended in any proportion depending on the SP of the required composite resin.
80 wt%, methacrylic acid ester resin 20 to 60 wt%, and ethylene carbonate 1 to 20 wt% are blended.

[0013]

[Function] The polyvinyl butyral resin and the methacrylic acid ester-based resin appear to be compatible with each other when dissolved in an organic solvent, but since they are incompatible, simply mixing these resins, The two resins undergo phase separation after drying, and not only cannot maintain a uniform dispersion state, but also gelation of the polyvinyl butyral resin is unavoidable due to reaction with the carboxylic acid group or alkoxy group from the compound of the additional element, Further, when an electrode is printed with an electrode paste using terpineol as a solvent, it becomes impractical because a weak methacrylic acid ester resin is affected by this solvent, but when ethylene carbonate is added to a mixture of these resins, The methacrylic acid ester resin, which is easily affected by terpineol, is modified by the reaction with ethylene carbonate and Nylbutyral resin has a hydrophilic and active OH group in its molecule that is modified by reacting with ethylene carbonate to become a composite resin, so that it is possible to print without trouble even with an electrode paste using terpineol as a solvent. Moreover, the reaction with the carboxylic acid groups or alkoxy groups from the metal soap added as an additive to the ceramic material is suppressed, so that the sheet can be formed without gelation.

[0014]

EXAMPLE Barium titanate, niobium octylate, neodymium octylate, acetylacetone cobalt (III), ethyl silicate, acetylacetone manganese were used as raw materials, and these were accurately weighed in terms of oxide according to the molar ratio shown in Table 1. The mixture was placed in a polyethylene pot having a capacity of 250 cc, 150 g of partially stabilized zirconia boulder having a diameter of 5 mm and 30 ml of toluene were added thereto, and the mixture was pulverized, mixed and dispersed for 16 hours on a pot rack to obtain a mixed powder.

[0015]

[Table 1] BaTiO ₃ CoO Nb ₂ O ₅ Nd ₂ O ₃ MnO SiO ₂ mol 100 0.47 0.90 0.014 0.14 0.16 0.31

51.3% by weight of polyvinyl butyral resin and 2 parts of polybutyl methacrylate were added to the mixed powder.
Using a composite resin composed of 5.6% and ethylene carbonate 23.1% as a binder, 7.5% by weight of barium titanate in terms of solid content was added, and 3% of dioctyl phthalate was added, and further mixed and dispersed for 5 hours. , A slurry was obtained.

The slurry is subjected to vacuum degassing to remove air from the slurry, formed into a sheet having a thickness of 20 μm by a doctor blade method, and then punched into a predetermined shape, and the green sheet thus obtained is provided with Ethocel and The internal electrodes were printed with an Ag-Pd paste consisting of terpineol and fine powder of silver and palladium. These green sheets were stacked, pressed and then cut to obtain a laminated chip. These laminated chips were fired at 1270 ° C. for 3 hours to obtain sintered chips.

Silver paste was applied to both ends of the sintered chip and baked at 800 ° C. to form external electrodes, and a multilayer capacitor chip was obtained, and the electrical characteristics were measured using this as a sample. The results are shown in Table 2 together with the results of Comparative Examples described later.

[0019]

Comparative Example 1 Example 1 was repeated except that polybutyl methacrylate was used as a binder instead of the composite resin, and 7.5% in terms of solid content was added to the mixed powder prepared in Example 1.
A multilayer capacitor chip was obtained by performing the same process as in (1).

[0020]

[Comparative Example 2] A polyvinyl butyral resin was used as a binder instead of the composite resin, and the same treatment as in Example 1 was carried out except that 7.5% of the solid content was added to the mixed powder prepared in Example 1. A multilayer capacitor chip was obtained.

[0021]

[Table 2] Dielectric constant tan δ Temperature characteristic CR product Example 4030 1.7% X7F (EIA) 13000 Comparative example 1 Internal electrode short-circuited and property measurement was not possible Comparative example 2 Binder in slurry gelled and sheet formation was not possible

As is clear from the results shown in Table 2, when the conventional binder for forming a green sheet is used, there is a problem that the sheet is affected and short-circuited when the internal electrode paste is printed, and the binder of the ceramic material is not used. While there is a problem that the binder gels due to the reaction with the binder and it becomes impossible to form a sheet, the binder according to the present invention can solve these problems.

[0023]

As described above, according to the present invention, a composite resin obtained by modifying a polyvinyl butyral resin and a methacrylic acid ester resin, which are incompatible with each other, with ethylene carbonate is used as a binder. Regardless of the chemical form of the solvent of the electrode paste or the raw material powder of the electronic ceramic, it is possible to form a good ceramic green sheet without causing wrinkles due to solvent penetration or gelation due to reaction with the raw material powder. .

Further, it is not necessary to prepare a plurality of kinds of internal electrode paste according to the binder used for forming the green sheet, and it is economical because one kind of internal electrode paste can be used for general purpose. The solvent can be freely selected. Furthermore, the modified resin has a molecular weight larger than the molecular weight of the raw material resin by the reaction with ethylene carbonate, and the mechanical strength is improved.
It is possible to obtain a ceramic green sheet having a higher strength than that obtained by using a conventional polyvinyl butyral resin alone or a methacrylate ester resin alone as a binder.

Claims (1)

[Claims] 1. A binder for forming a ceramic green sheet for a laminated electronic component, which comprises a polyvinyl butyral resin and a methacrylic acid ester-based resin as main components, and a composite resin obtained by modifying these with ethylene carbonate.