1. Field of the Invention
This invention relates generally to a fiber modified with carboxyl groups and, more specifically, to a cellulose or acrylonitrile fiber to which methacrylic acid or a hydroxyalkyl methacrylate is graft-copolymerized. The present invention is also directed to a process for producing such a modified fiber.
2. The Prior Art
One known method of introducing carboxyl groups into a cellulose fiber includes reacting monochloroacetic acid with the cellulose fiber. Because of the introduction of carboxylic groups, the cellulose fiber thus obtained has improved hydrophilicity and is capable of absorbing basic, bad odor substances such as amines and ammonia. The known method has, however, a problem that it is difficult to homogeneously react the monochloroacetic acid with a solid, bulky mass of cellulose fibers because the reaction is exothermic.
It is also known to introduce ether linkages into a cellulose fiber by reaction with a vinyl compound according to the Michael reaction. With this method, however, it is not possible to effectively introduce carboxyl groups into the cellulose fiber when an unsaturated carboxylic acid such as acrylic acid or maleic acid is used as the vinyl compound. Thus, in order to introduce carboxylic groups into the cellulose fiber by utilizing the Michael reaction, it is necessary to first react the cellulose fiber with acrylonitrile and to hydrolyze the cyano groups into carboxyl groups.
An acrylonitrile fiber has properties similar to wool but has a defect that the moisture or damp absorbing power is poor. No effective method is however known to impart hydrophilicity to the acrylonitrile fiber.
A method is known in which a vinyl monomer having an acidic group is graft-copolymerized to a polyester or polyamide fiber using am organic peroxide such as benzoyl peroxide.