A sulfonic acid modified polyvinyl alcohol resin comprising up to 15 mol % of a first comonomer comprising sulfonic acid groups. The modified polyvinyl alcohol resin has a hydroxyl unit content of at least 65 mol % and a gel fraction of 3.2 or less. Further, the modified polyvinyl alcohol resin has a disintegration time of 85 seconds or less, as measured in a mixture of 50 vol % water and 50 vol % isopropyl alcohol at 23° C. Additionally, the modified polyvinyl alcohol resin has a hard component present in a component ratio of 10% or greater and 55% or less and having a relaxation time of 0.0091 milliseconds or greater and 0.0104 milliseconds or less, as measured by the pulsed NMR Solid Echo method at 80° C. Also disclosed are methods for producing the sulfonic acid modified polyvinyl alcohol resins, which may advantageously be used in inks, paints, paper coatings, emulsions, or films.

Provided by the present invention are a dispersant for suspension polymerization which enables production of vinyl polymer particles having a small particle diameter at a small added amount, a method for producing such a dispersant for suspension polymerization, and a method for producing vinyl polymer particles by using such a dispersant for suspension polymerization.

Provided by the present invention are a dispersant for suspension polymerization which enables production of vinyl polymer particles having a small particle diameter at a small added amount, a method for producing such a dispersant for suspension polymerization, and a method for producing vinyl polymer particles by using such a dispersant for suspension polymerization.

An object of the present invention is to provide a PVA-based resin having a small distribution in degree of heat treatment in which the degree of heat treatment does not depend on a particle diameter. The polyvinyl alcohol-based resin of the present invention has an absorbance at 280 nm of 0.3 or more when being made to a 0.1 wt % aqueous solution and satisfies the following Formula (1): 0.9≤X.sub.1/Y.sub.1≤1.2 (in Formula (1), X.sub.1 represents an absorbance at 320 nm of a 0.1 wt % aqueous solution of a polyvinyl alcohol-based resin having a particle diameter larger than 1000 μm and 1680 μm or less, and Y.sub.1 represents an absorbance at 320 nm of a 0.1 wt % aqueous solution of a polyvinyl alcohol-based resin having a particle diameter larger than 212 μm and 500 μm or less).

An object of the present invention is to provide a PVA-based resin having a small distribution in degree of heat treatment in which the degree of heat treatment does not depend on a particle diameter. The polyvinyl alcohol-based resin of the present invention has an absorbance at 280 nm of 0.3 or more when being made to a 0.1 wt % aqueous solution and satisfies the following Formula (1): 0.9≤X.sub.1/Y.sub.1≤1.2 (in Formula (1), X.sub.1 represents an absorbance at 320 nm of a 0.1 wt % aqueous solution of a polyvinyl alcohol-based resin having a particle diameter larger than 1000 μm and 1680 μm or less, and Y.sub.1 represents an absorbance at 320 nm of a 0.1 wt % aqueous solution of a polyvinyl alcohol-based resin having a particle diameter larger than 212 μm and 500 μm or less).

The present invention provides a conductive paste which leaves less fine undissolved matter when dissolved in an organic solvent and thus can be easily filtrated, which has excellent printability, and which can exhibit excellent surface smoothness after printing. Provided is a conductive paste used for forming an electrode of a multilayer ceramic capacitor, the conductive paste containing: a polyvinyl acetal resin; an organic solvent; and a conductive powder, the polyvinyl acetal resin having a wave number A (cm.sup.−1) of a peak within a range of 3,100 to 3,700 cm.sup.−1 in an IR absorption spectrum measured using an infrared spectrophotometer; and a hydroxy group content (mol %), the wavenumber A of the peak and the hydroxy group content satisfying relations of the following formulas (1) and (2):

[(3,470−A)/Hydroxy group content]≤5.0  (1)

(3,470−A)≤150  (2)

wherein A is a wavenumber which is lower than 3,470 cm.sup.−1 and at which a transmittance a (%) satisfying [100−(100−X)/2] is exhibited, where X (%) is s minimum transmittance of the peak within the wavenumber range of 3,100 to 3,700 cm.sup.−1.

The present invention provides a conductive paste which leaves less fine undissolved matter when dissolved in an organic solvent and thus can be easily filtrated, which has excellent printability, and which can exhibit excellent surface smoothness after printing. Provided is a conductive paste used for forming an electrode of a multilayer ceramic capacitor, the conductive paste containing: a polyvinyl acetal resin; an organic solvent; and a conductive powder, the polyvinyl acetal resin having a wave number A (cm.sup.−1) of a peak within a range of 3,100 to 3,700 cm.sup.−1 in an IR absorption spectrum measured using an infrared spectrophotometer; and a hydroxy group content (mol %), the wavenumber A of the peak and the hydroxy group content satisfying relations of the following formulas (1) and (2):

[(3,470−A)/Hydroxy group content]≤5.0  (1)

(3,470−A)≤150  (2)

wherein A is a wavenumber which is lower than 3,470 cm.sup.−1 and at which a transmittance a (%) satisfying [100−(100−X)/2] is exhibited, where X (%) is s minimum transmittance of the peak within the wavenumber range of 3,100 to 3,700 cm.sup.−1.

The present invention relates to a polyvinyl alcohol-based resin, in which a block character (A) is less than 0.4, and an absorbance (B) at 320 nm in an ultraviolet absorption spectrum in the case of making the polyvinyl alcohol-based resin into a 0.1 wt % aqueous solution is 0.2 or more.

The present invention relates to a polyvinyl alcohol-based resin, in which a block character (A) is less than 0.4, and an absorbance (B) at 320 nm in an ultraviolet absorption spectrum in the case of making the polyvinyl alcohol-based resin into a 0.1 wt % aqueous solution is 0.2 or more.

The present invention relates to a polyvinyl alcohol-based resin, in which a block character (A) is less than 0.4, and an absorbance (B) at 320 nm in an ultraviolet absorption spectrum in the case of making the polyvinyl alcohol-based resin into a 0.1 wt % aqueous solution is 0.2 or more.