Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
1999-08-06
2001-05-15
Acquah, Samuel A. (Department: 1711)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C528S272000, C528S279000, C528S280000, C528S286000, C528S288000, C528S298000, C528S302000, C528S307000, C528S308000, C528S308600, C428S364000, C428S374000, C525S437000, C525S444000, C525S445000
Reexamination Certificate
active
06231976
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to fibers, particularly binder fibers, made from copolyesters and the copolyesters themselves. The copolyesters of the invention are generally formed from a glycol component containing 1,3- or 1,4-cyclohexanedimethanol and ethylene glycol and at least one dicarboxylic acid component. Such copolyesters may be formed into a variety of products, especially binder fibers for nonwoven fabrics, textile and industrial yarns, and composites.
BACKGROUND OF THE INVENTION
Nonwoven fabrics are widely used in a variety of products. For example, nonwoven fabrics are suitable for use in filters, roofing materials, composites, backing materials, linings, insulation, medical/surgical applications, bedding, tablecloths, and diapers. High loft batting nonwoven fabrics are used in a wide variety of products, including comforters, robe wear, and bra cups. Generally nonwoven fabrics are based on polyester, acrylic, nylon, 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 or reduce pilling, and uses 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 dl/g have been used in the past as binder fibers to bond polyester or other fibers. Copolyesters with lower I.V. values, however, were believed to not have adequate bonding strength.
It is well known that copolyesters can be prepared by 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. The use of ethylene glycol as the only diol, however, is accompanied by undesirable properties such as yellow discoloration and weak fiber binding properties. Indeed, such polymers tend to be opaque, crystalline polymers with high melting temperatures which may make them unsuitable for use as binder fibers. To remedy the problems with polyethylene terephthalates, polyethylene terephthalate copolyesters have been formed with 1,4-cyclohexanedimethanol or isophthalic acid.
Previous attempts at forming copolyesters with 1,4-cyclohexanedimethanol and terephthalic acid have focused upon copolyesters having high inherent viscosities, I.V., of greater than 0.6, due to the belief that low inherent viscosities would not possess adequate strength. In particular, it was believed that low inherent viscosity copolyesters were unable to provide adequate bonding strength to form commercially acceptable binder fibers. Indeed, previous polyethylene terephthalate copolyesters containing 1,4-cyclohexanedimethanol were made with inherent viscosities ranging from 0.6 to 0.8 dl/g to form binder fibers to bond polyesters or other fibers. However, such attempts have not been entirely successful in providing copolyesters having the desired high clarity and hue or bonding capability at low activation temperatures when in the form of a binder fiber.
Other attempts at forming copolyesters suitable for use as binder fibers have focused on polyethylene terephthalate copolyesters which have been formed with isophthalic acid and diethylene glycol. Such attempts have resulted in unicomponent and bicomponent binder fibers sold as BELLCOMBI® available from Unitika of Osaka, Japan, MELTY® available from Kanebo, Ltd. of Osaka, Japan, CELBOND® available from KoSa and the like. These products however, have failed to recognize the clarity, bonding temperature, bonding strength and cost benefits of forming copolyesters containing both isophthalic acid and 1,3- or 1,4-cyclohexanedimethanol.
There exists a need in the art for cost-effective copolyesters formed from 1,3- or 1,4-cyclohexanedimethanol, ethylene glycol, isophthalic acid and at least one dicarboxylic acid selected from terephthalic acid, naphthalenedicarboxylic acid, 1,3- or 1,4-cyclohexanedicarboxylic acid or esters thereof. Such copolyesters possess improved clarity and color as well as improved binder fiber bonding strength at low activation temperatures.
SUMMARY OF THE INVENTION
The invention answers the problems connected with previous binder fibers and copolyesters by providing binder fiber copolyesters having excellent color, thermoplastic flow and increased bonding versatility as well as catalysts for producing such copolyesters. The copolyesters of the invention are suitable for use in a wide variety of applications, such as binder fibers for making nonwoven fabrics and textile and industrial yarns.
More specifically, the invention provides copolyesters which are prepared with glycol 25 components and dicarboxylic acid components. The glycol component generally contains 1,3-and/or 1,4-cyclohexanedimethanol in an amount ranging from about 5 to 60 mole %, 1,3-propanediol propanediol in an amount of up to about 55 mole % and ethylene glycol in an amount ranging from about 40 to about 95 mole %. The dicarboxylic acid component generally contains at least about 50 mole % of an acid, anhydride, acid chloride or ester of an aromatic dicarboxylic acid containing from about 8 to about 14 carbon atoms, an aliphatic dicarboxylic acid containing from about 4 to about 12 carbon atoms, a cycloaliphatic dicarboxylic acid having about 8 to about 12 carbon atoms or mixtures thereof. In one preferred embodiment, the dicarboxylic acid component generally contains an acid, anhydride, acid chloride or ester of isophthalic acid in an amount ranging from at least 10 mole % to about 50 mole % and at least about 50 mole % of a dicarboxylic acid component selected from the group consisting of acids or esters of terephthalic acid, naphthalenedicarboxylic acid, 1,3- or 1,4-cyclohexanedicarboxylic acid and mixtures thereof.
The copolyester of the invention is formed such that the resulting copolyesters have excellent thermoplastic flow and bonding capability. Typically, the inherent viscosities of the copolyester is less than about 0.7 dl/g when employing greater than 10 mole % isophthalic acid, anhydride, acid chloride or ester thereof and less than about 0.6 dl/g when employing less than about 10% isophthalic acid, anhydride, acid chloride or ester thereof. Indeed, the copolyesters of the invention are particularly suited for use as binder fibers because the copolyesters can possess a lower I.V. which allows improved bonding of the binder fiber for nonwoven fabrics at relatively low temperatures. The invention is discussed in more detail below.
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p
Dean Leron R.
Haile William A.
McConnell Richard L.
Acquah Samuel A.
Eastman Chemical Company
Gwinnell Harry J.
Tubach Cheryl
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