Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1998-08-28
2001-03-06
Boykin, Terressa M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C528S272000
Reexamination Certificate
active
06197856
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to binder fibers made from copolyesters, the copolyesters themselves and catalysts and processes for producing the copolyesters. More particularly, the invention relates to copolyesters formed from 1,4-cyclohexanedimethanol, ethylene glycol and terephthalic acid, napthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid and esters or anhydrides thereof. Such copolyesters may be formed into a variety of products, especially binder fibers for nonwoven fabrics.
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 also 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.
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. 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, 5,668,243 and 5,668,243, the reactants are a glycol component and a dicarboxylic acid component. Typically, the dicarboxylic acid component is terephthalic acid and the dihydric alcohol is ethylene glycol. Such copolyesters are relatively inert, hydrophobic materials which are suitable for a wide variety of uses, including, molded articles, 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 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.
The preparation of copolyesters with ethylene glycol, 1,4-cyclohexanedimethanol and terephthalic acid is typically conducted in the presence of a catalyst materials. The choice of materials for such have generally focused on a variety of combinations of materials including catalysts derived from antimony, cadmium, calcium, gallium, germanium, lithium, magnesium, manganese, titanium, and zinc. An exemplary catalyst system for the preparation of polyethylene terephthalate is described in U.S. Pat. No. 3,907,754. Unfortunately, previous catalyst systems have not been entirely successfiil as they can produce copolyesters having an undesirable discoloration. Thus, there exists a need in the art for a catalyst system which provides efficient reaction times while producing high clarity copolyesters, especially high clarity copolyester binder fibers.
Furthermore, previous attempts at forming copolyesters with 1,4-cyclohexanedimethanol have focused upon copolyesters having high inherent viscosities, I.V. of greater than 0.6, due to the beliefs 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 having 1,4-cyclohexanedimethanol were made with inherent viscosities ranging from 0.6 to 0.8 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. Thus, there exists a need in the art for a copolyester having an inherent viscosity of less than 0.6 while possessing improved clarity, color and 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 in textile and industrial yarns.
More specifically, the invention provides copolyesters which are prepared with a glycol component and a dicarboxylic acid component. The glycol component generally contains 1, 4 cyclohexanedimethanol in an amount ranging from 10 to 60 mole % and ethylene glycol in an amount ranging from about 40 to about 90 mole %. At least about 90 mole % of the dicarboxylic acid component is selected from the group consisting of acids, esters or anhydrides of terephthalic acid, napthalenedicarboxylic acid, 1,4-cyclohexane dicarboxylic acid and mixtures thereof. The copolyester of the invention is formed such that the resulting copolyesters have inherent viscosities of less than 0.6 and excellent thermoplastic flow and bonding capability. Indeed, the copolyesters of the invention are particularly suited for use as binder fibers as the copolyesters 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.
DETAILED DESCRIPTION
The invention relates to binder fibers made from copolyesters, the copolyesters themselves and catalysts and processes for producing the copolyesters. The copolyesters of the invention possess excellent color as they are clearer, exhibit a neutral hue or brighter appearance than previous copolyesters and may accept dyes more easily than higher I.V. copolyesters. Indeed, through the use of a lower I.V. a copolyester polymer is formed which is clear and non opaque and may readily be processed into binder fibers having superior binding properties. Furthermore, the processing of the copolyesters into binder fibers is aided by the lower spin melt temperatures of the lowered I.V. copolyesters of the invention.
The copolyesters of the invention are formed from the reaction of a glycol component and a dicarboxylic acid component. Generally, the glycol component comprises 1, 4 cyclohexanedimethanol in an amount ranging from 10 to 60 mole % and ethylene glycol in an amount ranging from about 40 to about 90 mole %. The dicarboxylic acid component contains at least about 90 mole % of an acid, ester or anhydride of terephthalic acid, napthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid and mixtures thereof. The copolyesters of the invention possess an I.V. of between about 0.36 to 0.58. These features and others are discussed in more detail below.
Glycol Component
As mentioned above, the glycol component generally comprises 1, 4 cyclohexanedimethanol in an amount ranging from 10 to 60 mole % and ethylene glycol in an amount ranging from about 40 to about 90 mole %. Preferably the 1, 4 cyclohexanedimethanol is present in an amount ranging from about 20 to about 40 mole %, more preferably about 25 to about 35 mole %. The 1, 4 cyclohexanedimethanol may be a cis-, tran
Dean Leron R.
Dillow F. Henry
Haile William A.
Lambert Michael D.
Tincher Mark E.
Boykin Terressa M.
Eastman Chemical Company
Gwinnell Harry J.
Wood Jonathan D.
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