Abstract: Water dispersible polyesters are used to treat and size paper by applying them at the wet-end of the paper process. The water dispersible polyesters can be used alone or with other chemicals typically used to treat or size paper in order to increase the paper's dry strength, wet strength, stiffness, water repellency, water resistance, and sizing properties. The water dispersible polyester is made with recycled polyethylene terephthalate or fresh glycol and polyacid or with virgin polyethylene terephthalate. The polyester sized paper is repulpable and recyclable. If the polyester size is used with traditional wet-strength resins, such as Kymene, the polyester-Kymene mixture will be repulpable and recyclable, whereas Kymene by itself is not easily repulpable nor recyclable in a paper mill process.

Abstract: Water-soluble or water-dispersible and curable polyester resins are suitable as binders in various applications, The resins are reaction products of polyterephthalate, polyols, polyacids, end acids and crosslinking agents. The waste terephthalates can be utilized when making the binders of the present invention. The preferred polyol is pentaerythritol. The resins can be used as binder for glass fiber insulation products.