Polymeric monofilaments are used as reinforcements for rubbers, in fishing lines, in toothbrush bristles, in paintbrush bristles and the like. In addition, woven fabrics produced from monofilaments are used, for example, in industrial belts and paper machine clothing.
Polyester monofilaments offer high strength and good dimensional stability. For example, U.S. Pat. No. 3,051,212 and U.S. Pat. No. 3,869,427 disclose the use of polyester monofilaments as reinforcements for rubber articles. The use of polyester monofilaments to make fabric for processing and drying wet pulp to make paper is described in U.S. Pat. No. 3,858,623, U.S. Pat. No. 4,071,050, U.S. Pat. No. 4,374,960, U.S. Pat. No. 5,169,499, U.S. Pat. No. 5,169,711, U.S. Pat. No. 5,283,110, U.S. Pat. No. 5,297,590, U.S. Pat. No. 5,635,298, U.S. Pat. No. 5,692,938, U.S. Pat. No. 5,885,709, and Kirk-Othmer Encyclopedia of Chemical Technology (2nd Ed.) (Interscience) 1967, Vol. 14, pp. 503–508 and the references cited therein. For example, linear poly(ethylene terephthalate)s having inherent viscosities between 0.60 and 1.0 dL/g are known for use in the production of monofilaments. Generally, it has been disclosed that the inherent viscosity is greater than 0.70 dL/g. U.S. Pat. No. 3,051,212, U.S. Pat. No. 3,627,867, U.S. Pat. No. 3,657,191, U.S. Pat. No. 3,869,427, U.S. Pat. No. 3,959,215, U.S. Pat. No. 3,959,228, U.S. Pat. No. 3,975,329, U.S. Pat. No. 4,016,142, U.S. Pat. No. 4,017,463, U.S. Pat. No. 4,139,521, U.S. Pat. No. 4,374,960, U.S. Pat. No. 5,472,780, U.S. Pat. No. 5,635,298, U.S. Pat. No. 5,763,538, and U.S. Pat. No. 5,885,709 disclose the use of high molecular weight, linear polyesters for use in the manufacture of monofilaments. The inherent viscosity of a polymer is an indicator of its molecular weight.
For many end uses, hydrolysis resistance is desired. Enhancement of hydrolysis resistance by reducing the content of carboxyl end groups is disclosed, for example, in U.S. Pat. No. 3,051,212, U.S. Pat. No. 3,657,191, U.S. Pat. No. 4,139,521, U.S. Pat. No. 4,374,961, U.S. Pat. No. 5,246,992, U.S. Pat. No. 5,378,537 and references cited therein. Hydrolysis stabilization additives have also been disclosed. Generally, the hydrolysis stabilization additives have been disclosed to function by reacting with free polymeric carboxyl end groups. U.S. Pat. No. 3,051,212 and U.S. Pat. No. 4,374,960 disclose the use of diazomethane to “cap” the polyester carboxyl end groups to enhance the hydrolysis resistance. Carbodiimides are disclosed as polyester hydrolysis stabilization additives in U.S. Pat. No. 3,193,522, U.S. Pat. No. 3,193,523, U.S. Pat. No. 3,975,329, U.S. Pat. No. 5,169,499, U.S. Pat. No. 5,169,711, U.S. Pat. No. 5,246,992, U.S. Pat. No. 5,378,537, U.S. Pat. No. 5,464,890, U.S. Pat. No. 5,686,552, U.S. Pat. No. 5,763,538, U.S. Pat. No. 5,885,709 and U.S. Pat. No. 5,886,088. Epoxides are disclosed as polyester hydrolysis stabilization additives in U.S. Pat. No. 3,627,867, U.S. Pat. No. 3,657,191, U.S. Pat. No. 3,869,427, U.S. Pat. No. 4,016,142, U.S. Pat. No. 4,071,504, U.S. Pat. No. 4,139,521, U.S. Pat. No. 4,144,285, U.S. Pat. No. 4,374,960, U.S. Pat. No. 4,520,174, U.S. Pat. No. 4,520,175, and U.S. Pat. No. 5,763,538. Cyclic carbonates, such as ethylene carbonate, are disclosed as hydrolysis stabilization additives in U.S. Pat. No. 3,657,191, U.S. Pat. No. 4,374,960, and U.S. Pat. No. 4,374,961. U.S. Pat. No. 3,959,215 discloses the use of phenylene bisoxazolines for the stabilization of polyesters. Aziridine compounds have been disclosed in the production of low carboxyl polyesters in U.S. Pat. No. 3,959,228 and U.S. Pat. No. 5,763,538. U.S. Pat. No. 5,763,538 discloses the use of keteneimines and isocyanates as polyester monofilament hydrolysis stabilization additives.
Monofilaments having desired surface characteristics can be prepared, for example, by the application of a coating to preformed monofilaments or by the melt spinning of sheath-core bicomponent monofilaments. Monofilaments can also be treated after having been woven into fabrics, as, for example, disclosed by Beaumont, et al., in U.S. Pat. No. 3,032,441. Fleischer, et al., in U.S. Pat. No. 4,731,281, discloses the coating of monofilaments with polymeric solutions or dispersions. Cordova, et al., in U.S. Pat. No. 4,767,646, discloses aqueous based overfinish compositions for monofilaments, which include an oxidized polyethylene emulsified with a non-nitrogen, nonionic emulsifier and neutralized with an alkali hydroxide and a compound selected from the group consisting of a siloxane of the comonomers dimethyl and 3-[(2-aminoethyl)aminopropyl], and an amide melamine wax. Leydon, et al., in U.S. Pat. No. 5,580,609, discloses a method to produce a monofilament coated with an amide melamine wax.
Polyester monofilaments having coatings with improved adhesion to the monofilaments are desired. The processes and monofilaments disclosed herein utilize certain copolymers as adhesives or tie layers that provide enhanced adhesion between the coating materials and the monofilament.