Water-soluble film, and chemical agents-enclosing packaging capsule material having same

A water-soluble film for molding a packaging capsule for enclosing chemical agents,

• comprising anion-group-modified polyvinyl alcohols including repeating units from a fatty acid vinyl ester comonomer and anion-group-containing repeating units, in which a degree of saponification thereof is set from 91 mol % or more to 99 mol % or less, and a degree of modification by anion groups is set from 1.0 mol % or more to 6.0 mol % or less,
• wherein a total amount of anion-group modification of the anion-group-modified polyvinyl alcohols is set from 1.0 mol % or more to 3.5 mol % or less,
• being formed by including from 22 parts by mass or more to less than 45 parts by mass of a plasticizer and at least 0.2 parts by mass of a surfactant, per 100 parts by mass of a total amount of the anion-group-modified polyvinyl alcohols,
• having a thickness of from 20 μm or more to 100 μm or less,
• having a tensile modulus of 20 MPa or more to 100 MPa or less determined in accordance with JIS K 7127 (1999) under conditions of:
• Measurement environment:
• 23° C., 50% RH,
• Film specimen:
• width 15 mm×length 150 mm,
• Film water content:
• 5-9%,
• Distance between chucks:
• 100 mm, and
• Tensile test speed:
• 300 mm/min,
• wherein the anion-group-modified polyvinyl alcohols consist of a first anion-group-modified polyvinyl alcohol having a degree of saponification from 91 mol % or more to 96 mol % or less and a degree of polymerization of 1,600 or more to 1,900 or less, and a second anion-group-modified polyvinyl alcohol having a degree of saponification from 95 mol % or more to 99 mol % or less and a degree of polymerization of 1,600 or more to 1,900 or less,
• wherein a mass ratio between the first anion-group-modified polyvinyl alcohol and the second anion-group-modified polyvinyl alcohol is 20-80:80-20,
• wherein the respective repeating units from the fatty acid vinyl ester comonomer and the anion-group-containing repeating units of the first anion-group-modified polyvinyl alcohol and the second anion-group-modified polyvinyl alcohol are the same,
• wherein the anion-group-containing repeating units are selected from the group consisting of maleic acid, itaconic acid, and fumaric acid,
• wherein the degree of saponification of the first anion-group-modified polyvinyl alcohol is lower than the degree of saponification of the second anion-group-modified polyvinyl alcohol;
• and
• wherein a time for starting a dispersion of the water-soluble film under stirring in water at 20° C. is 30 seconds or more at a film thickness of 75 μm, and is 40 seconds or more at a film thickness of 90 μm, and/or a time for starting a dissolution of the water-soluble film under static immersion in water at 20° C. is 50 seconds or more at a film thickness of 75 μm, and is 70 seconds or more at a film thickness of 90 μm.