Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
2002-10-23
2003-06-24
Acquah, Samuel A. (Department: 1711)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C428S370000, C428S375000, C428S394000, C528S277000, C528S279000, C528S280000, C528S281000, C528S282000, C528S283000
Reexamination Certificate
active
06582818
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to fibers, particularly binder fibers, made from polyesters and the polyesters themselves. The polyesters are the product of a reaction between a glycol component and a dicarboxylic acid component where the glycol component contains at least 50 mole % of a four carbon diol, such as 1,4-butanediol, or a six carbon diol, such as 1,6-hexanediol or a mixture of a four carbon and six carbon diol. Typically, the polyesters of the invention are semicrystalline and/or crystalline and have a specific melting point ranging from about 140 to about 185° C. The polyesters of the invention may be formed into a variety of products, especially binder fibers for nonwoven fabrics, textile/industrial yarns and fabrics, composites and other molded articles.
BACKGROUND OF THE INVENTION
It is well known that copolyesters can be prepared using processes involving polyesterification and polycondensation. Generally, as described in U.S. Pat. Nos. 2,901,466, 5,017,680, 5,106,944 and 5,668,243, the reactants include glycol components and dicarboxylic acid components. Typically, one dicarboxylic acid component is terephthalic acid and one dihydric alcohol is ethylene glycol. Such copolyesters are relatively inert, hydrophobic materials which are suitable for a wide variety of uses, including, molded articles, such as those used in the automobile and appliance industries, food trays, fibers, sheeting, films and containers, such as bottles. Unmodified poly(ethylene terephthalate) (PET) is very high melting (Tm=255° C.) and is therefore unsuitable for use in bonding nonwoven fiber and film laminates for use in the automotive industry.
Nonwoven fabrics are widely used in a variety of products. For example, nonwoven fabrics are suitable for use in automotive applications, composites, filters, roofing materials, backing materials, linings, insulation, face masks, medical/surgical, bedding, tablecloths, napkins, hygiene and absorbent products. High loft nonwoven battings are also used in a number of products, including comforters, robe wear, and bra cups. Generally, nonwoven fabrics are based on polyester, acrylic, nylon, carbon, glass and cellulosic fibers which may be bonded with latex adhesives, binder fibers, or polymers in powder form. The bonding of nonwoven fabrics with binder fibers provides a convenient method for making nonwoven fabrics without the need for water-based adhesives which are less environmentally friendly. Nonwoven fabrics bonded with binder fibers are economical to produce, and provide a method for making articles, which are unique or superior in performance. Other applications are uses in yarns to increase strength and reduce pilling or linting, as well as in prepregs, preforms and a wide range of composite structures.
Certain copolyesters have been found to be useful as binder fibers. For example, polyethylene terephthalate (PET) copolyesters containing 1,4-cyclohexanedimethanol having inherent viscosity (I.V.) values in the range of about 0.6 to about 0.8 have been used in the past as binder fibers to bond polyester or other fibers. However, many of these polymers are amorphous or only slightly crystalline. Fibers made from these polymers are not fully suitable for automotive applications such as headliners which can be exposed to elevated temperatures in closed cars parked in hot climates.
Generally, as described in U.S. Pat. Nos. 4,217,426 and 4,419,507, linear, crystalline or partially crystalline polymers have been reported as useful for forming fusible interlining adhesives and in some instances as binder fibers. Indeed, binder fibers and powders made from poly (hexamethylene terephthalate) copolyesters (PHT) have been sold. Such powders and binder fibers include Eastobond FA 300 which was formed from a copolyester having 20 mole % 1,4-butanediol and had a melting point of about 125° C. as well as Eastobond FA 250 which contained 20 mole % isophthalic acid and 20 mole % 1,4-butanediol and had a melting point of about 104° C.
While previous polyesters and binder fibers may be suitable for certain purposes, such polyesters have not proven effective for repeatedly withstanding temperatures of up to about 110° C. without losing bond integrity.
SUMMARY OF THE INVENTION
The invention answers the problems connected with previous binder fibers and polyesters by providing polyesters which are formed from the reaction products of at least about 50 mole % of a glycol having either four or six carbon atoms and by controlling the amounts of diethylene glycol and ethylene glycol to less than about 20 mole % of the glycol component. Through the use of the invention, polyester products can be formed which can repeatedly withstand temperatures of up to about 110° C. without losing bond integrity. Further, by controlling the types of catalyst systems employed in the reaction of the dicarboxylic acid and glycol components, copolyesters or copolyester pellets having improved color may be formed.
The invention further answers the problems by providing polyesters having excellent elasticity properties, improved color and dyeing properties, superior thermoplastic flow characteristics and increased bonding versatility. The polyesters of the invention are suitable for use in a wide variety of applications, including molded products, such as those used in the automotive industry and binder fibers for making nonwoven battings and fabrics, textile and industrial yarns, and composites.
More specifically, the invention provides polyesters which are prepared with glycol components and dicarboxylic acid components. Generally, the glycol component contains more than about 50 mole % of a glycol having either four or six carbon atoms and less than about 20 mole % of ethylene glycol or diethylene glycol. Preferably, the glycol component is 1,4-butanediol or 1,6-hexanediol or a mixture thereof. Typically, the dicarboxylic acid component contains at least about 50 mole % of a dicarboxylic acid component which is an acid, anhydride, acid chloride or ester of an aromatic dicarboxylic acid containing from about 8 to about 14 carbon atoms, a cycloaliphatic dicarboxylic acid having about 8 to about 12 carbon atoms or mixtures thereof. Additionally, the dicarboxylic acid component will generally contain about 0 to about 45 mole % of one or more aliphatic dicarboxylic acids containing from about 4 to about 12 carbon atoms.
Generally, the polyesters of the invention have melting points in the range of about 140° to about 185° C. and are semicrystalline or crystalline and may be used to form crystallizable binder fibers., Furthermore, the polyesters of the invention when formed into a bonded structure typically possess elastic bonds which are less susceptible to cracking when subjected to repeated flexing. Thus, preferred fibers of the invention are capable of maintaining the shape and appearance of the bonded product over time. The invention is discussed in more detail below.
DETAILED DESCRIPTION OF THE INVENTION
The invention relates to fibers, particularly binder fibers, made from polyesters, as well as the polyesters themselves. The polyesters of the invention are formed from the reaction of a glycol component and a dicarboxylic acid component. As used in this application, the term polyester is intended to encompass both polyesters formed from one glycol and one dicarboxylic acid and copolyesters which are formed from more than one glycol and/or more than one dicarboxylic acid component.
The polyesters of the invention tend to possess good color and may accept dyes more easily than previous polyesters. Indeed, with the invention, semicrystalline or crystalline polyester polymers may be formed and readily be processed into binder fibers having excellent binding properties. Furthermore, the selection of the glycol component and the dicarboxylic acid component may be controlled to form either crystalline or amorphous polyesters with glass transition temperatures preferably lower than that of polyethylene terephthalate. It is preferred that the polyesters of the invention a
Dean Leron R.
Haile William A.
Khemani Kishan C.
McConnell Richard L.
Acquah Samuel A.
Boshears B. J.
Eastman Chemical Company
Graves Bernard
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