KR-102963511-B1 - Polyvinyl acetal resin and resin composition for ceramic green sheets

Abstract

The present invention provides a polyvinyl acetal resin and a resin composition for a ceramic green sheet that can produce a ceramic green sheet with excellent dispersibility and dispersion stability of the ceramic powder, high strength, and is resistant to delamination or dimensional changes during drying, and can manufacture a multilayer ceramic capacitor with excellent reliability. The present invention is a polyvinyl acetal resin having a Z average molecular weight (Mz) of 700,000 or more and 2,500,000 or less, and a molecular weight differential distribution value at LogM = 6.00 of 5.00 or more and 110.0 or less.

Inventors

• 마에다 다카유키

Assignees

• 세키스이가가쿠 고교가부시키가이샤

Dates

Publication Date

20260511

Application Date

20240523

Priority Date

20230526

Claims (4)

1. The average molecular weight Z (Mz) is 800,000 or more and 2,300,000 or less, and Polyvinyl acetal resin having a molecular weight differential distribution value of 8.00 or more and 95.00 or less at LogM = 6.00.
2. In Article 1, Polyvinyl acetal resin having a hydroxyl group content (mol%) relative to the Z average molecular weight (hydroxyl group content/Z average molecular weight) of 1.30 × 10⁻⁵ or more and 2.70 × 10⁻⁵ or less.
3. In Article 1 or Article 2, Polyvinyl acetal resin having an acetal content (mol%) of 50 to 83 mol%.
4. A resin composition for ceramic green sheets comprising a polyvinyl acetal resin as described in claim 1 or 2 and a plasticizer.

Description

Polyvinyl acetal resin and resin composition for ceramic green sheets The present invention relates to a polyvinyl acetal resin and a resin composition for ceramic green. Recently, the miniaturization and stacking of electronic components installed in various electronic devices are progressing, and stacked electronic components such as multilayer circuit boards, stacked coils, and stacked ceramic capacitors are being widely used. Among them, multilayer ceramic capacitors are generally manufactured through the following processes. First, a plasticizer, a dispersant, etc. are added to a solution in which a binder resin, such as polyvinyl butyral resin or poly(meth)acrylic acid ester-based resin, is dissolved in an organic solvent, and then ceramic raw material powder is added and uniformly mixed using a mixing device such as a bead mill or a ball mill, and after degassing, a ceramic slurry composition having a certain viscosity is obtained. This slurry composition is applied to a support surface, such as a polyethylene terephthalate film or a SUS plate, that has undergone release treatment using a doctor blade or a reverse roll coater, and then volatile components such as solvent are removed by distillation through heating, etc., and then peeled off from the support to obtain a ceramic green sheet. Next, multiple sheets of a conductive paste serving as an internal electrode are alternately stacked and heat-pressed onto the obtained ceramic green sheets by screen printing to manufacture a laminate. Subsequently, a so-called degreasing treatment is performed to remove binder resin components and other substances contained in the laminate by thermal decomposition, and an external electrode is sintered onto the cross-section of the ceramic sintered body obtained by firing to obtain a multilayer ceramic capacitor. The resin composition for ceramic green sheets used in the manufacture of ceramic green sheets is generally used as a solution in which polyvinyl acetal resin is dissolved in organic solvents such as methyl ethyl ketone, toluene, alcohol, and mixtures thereof. However, when conventional polyvinyl acetal resin is dissolved in organic solvents, trace amounts of undissolved material are generated. If such undissolved material is present, when used in multilayer ceramic capacitors, voids tend to remain during the degreasing and firing processes, or the dispersibility of ceramic powders is reduced, thereby degrading the electrical properties of the resulting product. For this reason, when using polyvinyl acetal resin for ceramic green sheets, it was necessary to remove undissolved substances by mixing organic and inorganic compounds, dissolving them in an organic solvent, and then performing a filtration process. In this regard, Patent Document 1 proposes a polyvinyl acetal resin in which the reduction rate of the filtration flow rate is less than 10% when a polyvinyl acetal resin solution, prepared as a 5 wt% solution by dissolving it in a 1:1 mixed solvent of methyl ethyl ketone and/or toluene and ethanol, is filtered using a filter with a mesh size of 5 μm under conditions of a filtration temperature of 25°C and a filtration pressure of 10 mmHg. Furthermore, it is stated that by using such a polyvinyl acetal resin, there is less undissolved material when dissolved in an organic solvent, and thus the filtration time can be shortened, thereby improving productivity. Figure 1 is a diagram showing an example of a molecular weight differential distribution curve. The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples. (Example 1) 300 g of pure water was added to 300 g of polyvinyl alcohol resin (average degree of polymerization 1,700, degree of saponification 99.0 mol%) and dissolved by stirring at 90 ℃ for about 2 hours. This solution was cooled to 20 ℃, and 120 g of hydrochloric acid with a concentration of 35 wt% and 140 g of n-butylaldehyde were added to it. The temperature was raised at a rate of 0.2 ℃/min (heating time 250 min), and an acetalization reaction was carried out by maintaining at 70 ℃ for 3 hours. After completing the reaction, neutralization, washing, and drying were performed by conventional methods to obtain a white powder of polyvinyl acetal resin. (Preparation of resin composition for ceramic green sheets) A resin composition for a ceramic green sheet was obtained by adding 1.25 parts by weight of the obtained polyvinyl acetal resin to 48.75 parts by weight of an ethanol/toluene mixed solvent (weight ratio 1:1) and stirring to dissolve it. (Manufacture of resin sheets) A resin sheet was prepared by coating the obtained resin composition for a ceramic green sheet onto a PET film that had been released using a coater so that the thickness after drying was 20 μm, and then heating and drying it at 70°C for 60 minutes. (Preparation of slurry composition) A resin solution was prepared by adding 2 parts