The present invention provides a method for stably providing a product. The present invention relates to a heat exchanger configured to handle an easily-polymerizable compound-containing solution or an easily-polymerizable compound crystal-containing slurry, the heat exchanger including a scraper for scraping off a substance adhered to an inner wall surface thereof, a shaft connected to the scraper, and a bushing on the shaft, the bushing being to be in contact with the solution or slurry when the heat exchanger is used and being made of an aromatic polyetherketone-containing material.

The present invention provides a method for stably providing a product. The present invention relates to a heat exchanger configured to handle an easily-polymerizable compound-containing solution or an easily-polymerizable compound crystal-containing slurry, the heat exchanger including a scraper for scraping off a substance adhered to an inner wall surface thereof, a shaft connected to the scraper, and a bushing on the shaft, the bushing being to be in contact with the solution or slurry when the heat exchanger is used and being made of an aromatic polyetherketone-containing material.