Cataplasm and method for producing the same

A gel patch, comprising:

• a plaster layer on a support, the plaster layer comprising:
• a mixture of at least a neutralized polyacrylic acid, a poly(methyl acrylate/2-ethylhexyl acrylate) emulsion, and water, wherein the poly(methyl acrylate/2-ethylhexyl acrylate) emulsion comprises poly(methyl acrylate/2-ethylhexyl acrylate) and water as a medium, wherein the poly(methyl acrylate/2-ethylhexyl acrylate) emulsion is an emulsion having an evaporation residue of 57 to 61% at or above the boiling point of the medium and is present in an amount ranging between 2.5 times and 10 times inclusive a mass of the neutralized polyacrylic acid;
• and
• a polyacrylic acid in the amount of 1-5 mass % based on the total mass of the plaster layer, wherein the neutralized polyacrylic acid present in the plaster layer is 1 to 6 mass %, based on a total mass of the plaster layer;
• wherein the gel patch has an adhesive force based on an adhesive force of the poly(methyl acrylate/2-ethylhexyl acrylate) in the poly(methyl acrylate/2-ethylhexyl acrylate) emulsion and an adhesive force of the neutralized polyacrylic acid, and
• wherein upon application, the adhesive force of the neutralized polyacrylic acid is greater than the adhesive force of the poly(methyl acrylate/2-ethylhexyl acrylate), and the adhesive force of the poly(methyl acrylate/2-ethylhexyl acrylate) increases to become greater than the adhesive force of the neutralized polyacrylic acid as the amount of water in the plaster layer is reduced.