Method of spraying chemical solution

A method of spraying a chemical solution, the method comprising spraying a chemical solution continuously on a canvas used in a dry part of a paper machine by a spraying apparatus while making the canvas travel,

• wherein the canvas is guided to an inside roll and an outside roll, and
• wherein the spraying apparatus is disposed upstream from the outside roll and between the inside roll and the outside roll, and the chemical solution is sprayed toward the outside roll along a travel direction of the canvas,
• wherein in a case where a distance L (mm) between a point of contact of the canvas with a perpendicular from a nozzle tip of the spraying apparatus to the canvas and a point of contact of the outside roll with the canvas is 80≤L<400, an angle θ formed by a spraying direction of the spraying apparatus and the travel direction of the canvas is 10≤θ≤30 degrees, and
• wherein in a case where the distance L (mm) is 400≤L≤5000, the angle θ formed by the spraying direction of the spraying apparatus and the travel direction of the canvas is 30≤θ≤60 degrees,
• wherein the spraying apparatus is a scanning type nozzle apparatus that sprays a chemical solution on the canvas while reciprocating in a direction perpendicular to the travel direction of the canvas,
• wherein a moving distance H of the nozzle apparatus during one rotation of the canvas and a width W of a portion sprayed on the canvas by the nozzle apparatus satisfy the following relationship:
• 0.5≤H/W≤12
• wherein the moving distance H of the nozzle apparatus is from 15 mm to 1800 mm,
• wherein the width W of the sprayed portion by the nozzle apparatus is from 30 to 150 mm,
• an overall width of the canvas in a direction perpendicular to the travel direction of the canvas is in a range of 3000 mm to 9000 mm,
• an overall length of the canvas in the travel direction of the canvas is in a range of 25000 mm to 90000 mm, and
• wherein a time required for one rotation of the canvas is in a range of 1 second to 20 seconds.