MXPA00001984A - Improved copolymer binder fibers - Google Patents

Abstract

The invention relates to binder fibers made from copolyester, 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-cyclohexane dicarboxylic acid and esters or anhydrides thereof. Such copolyesters may be formed into a variety of products, especially binder fibers for nonwoven fabrics.

Description

COPOLYMER FIBERS, AGGLUTINANTS, IMPROVED Field of Invention The invention relates to binder fibers made from copolyes teres, to the same copolyests and to catalysts and processes for producing copolyes teres. More particularly, the invention relates to copolyes tere s formed of 1, -cyclohexanediol tannol, ethylene glycol and terephthalic acid, naphthalenedicarboxylic acid, 1-cyclohexanedicarboxylic acid and esters or anhydrides thereof. Such copolyes can be formed into a variety of products, especially binder fibers for non-woven fabrics.

Background of the Invention Non-woven fabrics are widely used in a variety of products. For example, non-woven fabrics are suitable for use in filters, roofing materials, compositions, backing materials, coatings, insulation, medical / surgical applications, bedding, tablecloths, and diapers. Non-woven fabrics high in Ref: 32824 Wadding (cotton sheets) are also used in a wide variety of products, including quilts, dressing gowns, and brass cups. Generally non-woven fabrics are based on polyester, acrylic, nylon, glass and cellulosic fibers which can be bonded with latex adhesives, binding fibers, or polymers in powder form. The bonding of non-woven fabrics with binding fibers provides a convenient method for making non-woven fabrics without the need for water-based adhesives that are less environmentally friendly. Non-woven fabrics bonded with binding fibers are inexpensive to produce, and provide a method for making articles, which are unique or superior in performance.

Certain copolyes teres have been found to be useful as binder fibers. For example, copolymers of polyethylene terephthalate (PET) containing 1, -cyclohexanediol tanol having inherent viscosity values (Vl) in the range from 0.6 to about 0.8 have been used in the past as binder fibers to bind polyester to other fibers . Copolymers with low V.I. values, however, are believed to have no adequate bond strength.

It is well known that copolymers can be prepared by processes involving polyesterification and polycondensation. Generally, as described in U.S. Patent Nos. 2,901,466, 5,017,680, 5,106,944, 5,668,243 and 5,668,243, the reactants are glycol compounds and a dicarboxylic acid component. Typically, the dicarboxylic acid component is terephthalic acid and the dihydric alcohol is ethylene glycol. Such copolyests are relatively inert, hydrophobic materials that are suitable for a wide variety of uses, including molded articles, food dishes, fibers, sheets, films and containers, such as bottles. The use of ethylene glycol as the sole diol, however, is accompanied by undesirable properties such as yellowish discoloration and weak fiber bonding 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 copolyests have been formed with 1,4-cyclohexanedimethanol.

The preparation of the copolymers with ethylene glycol, 1,4-cyclohexanedimethanol and terephthalic acid is typically conducted in the presence of catalyst materials. The choice of materials for this is generally focused on a variety of material combinations 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. Patent 3,907,754. Unfortunately, previous catalyst systems are not completely successful as they can produce copolymers that have undesirable discoloration. Thus, there is a need in the art for catalyst systems that provide efficient reaction times while producing high clarity copolyes, especially high clarity copolyester binder fibers.

In addition, previous attempts to form copolyes teres with 1, 4-ci clohexandime t anol have focused on copolyesters having high inherent viscosities, V.l. of more than 0.6 due to the belief that inherent low viscosities may not possess adequate strength. In particular, it is believed that the inherent low viscosity copolyests are not capable of providing adequate bond strength to form commercially acceptable binder fibers. Indeed, the previous polyethylene terephthalate copolyes having 1,4-cyclohexanedime t anol were made with inherent viscosities in the range of 0.6 to 0.8 to form binder fibers for binding polyesters or other fibers. However, such attempts have not been completely successful in providing copolyests having the desired high clarity and the ability to tint or bond at low activation temperatures when in the form of binder fibers. Thus, there is a need in the art for copolyesters having inherent viscosities of less than 0.6 while possessing improved clarity, color strength and bonding of binder fibers at low activation temperatures.

Brief description of the invention.

The invention solves the problems related to copolyes teres and the above binder fibers by providing copolymer binder fibers having excellent color, thermoplastic flux and increased binding versatility as well as catalysts for producing such copolyes. The copolyesters of the invention are suitable for use in a wide variety of applications, such as binder fibers for making non-woven fabrics in textile and industrial yarns.

More specifically, the invention provides copolymers which are prepared with a glycol component and a dicarboxylic acid component. The glycol component generally contains 1,4-cyclohexandime t anol in an amount in the range of 10 to 60 mol% and ethylene glycol in an amount in the range from about 40 to about 90 mol%. At least about 90 mol% of the dicarboxylic acid component is selected from the group consisting of acids, esters or anhydrides of terephthalic acid, naphthalenedicarboxylic acid, 1-cyclohexanedicarboxylic acid and mixtures thereof. The copolyester of the invention is formed in such a way that copolyestes have inherent viscosities of less than 0.6 and an excellent thermoplastic flow and bonding capacity. In effect, the copolyesters of the invention are particularly suitable for use as binder fibers such as copolyesters having a low V.l. which improves the binding of the binder fiber for non-woven fabrics at relatively low temperatures. The invention is discussed in more detail below.

Detailed description of the invention.

The invention relates to binder fibers made of copolymers, copolymers and catalysts and processes for producing copolyesters. The copolyes tere s of the invention possess excellent color and are clear, exhibit a neutral hue or brighter appearance than the previous copolyes and can accept dyes more easily than copolyes teres of high V.l. Indeed, through the use of a low V.I., a copolyester polymer is formed which is clear and non-opaque and can be easily processed into binder fibers having superior bonding properties. In addition, the processing of the copolyes teres in the binder fibers is aided by the lower spinning melt temperatures of the low V.l. copolymers. 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-cyclohexanedimethylene in an amount in the range of 10 to 60 mol% and ethylene glycol in an amount in the range from about 40 to about 90 mol%. The dicarboxylic acid component contains at least about 90 mol% of an acid, ester or anhydride of terephthalic acid, naphthandicarboxylic acid, 1,4-cyclohexanedicarboxylic acid and mixtures thereof. The copolyests of the invention possess an I.V. from around 0.36 to 0.58. These descriptions and others are discussed in more detail below.

Glycol component As mentioned above, the glycol component generally comprises 1,4-cyclohexanedimethylene in an amount in the range of 10 to 60 mol% and ethylene glycol in an amount in the range of 40 to about 90 mol%. Preferably, the 1,4-cyclohexanedioneol is present in an amount in the range from about 20 to about 40 mol%, more preferably from about 25 to about 35 mol%. The 1,4-cyclohexanedimethanol can be a cis-, trans-, or cis / trans mixture of isomers. The ethylene glycol is preferably present in an amount in the range from about 60 to about 80 mol% and more preferably about 65 to 75 mol%.

In addition to 1,4-cyclohexanedimethanol and ethylene glycol, the glycol component can include more than about 20 mol%, and preferably more than about 4 mol% of diethylene glycol and also more than about 10 mol% of conventional glycols including , but not limited to, glycols containing from about 3 to about 12 carbon atoms such as propylene glycol, 1,3-propanediol, 1,4-bu t-anodiol, 1,5-pen t-anodiol, neopentyl glycol, 2 , 2-dimethyl-1,3-propanediol, 1,6-hexanediol, 2, 2, 4 -trimethyl-1, 3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 2,2, 4,4-tetramethyl-l, 3-cyclobutanediol, 2,4-dimethyl-2-ethylhexane-l, 3-diol, 2-ethyl-2-isobutyl-1,3-propanediol, 1,3-but-anodiol, neopentyl glycol, 1,8-octanediol, 2,2,4-trimethyl-1,6-hexanediol, thiodiethanol, 1,2-cyclohexanedimethanol, and 1,3-cyclohexanedimethanol.

Component of Dicarboxylic Acid The dicarboxylic acid component contains about 90% more than an acid, ester or anhydride of terephthalic acid, naphthanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid. It can be noted that any of the isomers of naphthanedicarboxylic acid or mixtures of isomers can be used with the 1,4-, 1,5-, 2,6- and 2,7-isomers being preferred. In addition, the 1,4-cyclohexanedicarboxylic acid moieties may be as cis-, trans- or cis / trans isomer mixtures. The preferred dicarboxylic acid component is dimethyl terephthalate.

Additional dicarboxylic acid components, (other than the acids, esters or anhydrides of terephthalic acid, naphthanedicarboxylic acid, and 1,4-cydohexane dicarboxylic acid), may be added in amounts of more than 10 mol%. Additional suitable dicarboxylic acid components contain about 4 to about 40 carbon atoms and are described in U.S. Patent Nos. 5,608,031 and 5,668,243, incorporated herein by reference. The additional dicarboxylic acid component is preferably an acid, ester or anhydride of an aromatic dicarboxylic acid, preferably having from 8 to 14 carbon atoms, an aliphatic dicarboxylic acid, preferably having from 4 to 12 carbon atoms, or an acid cycloaliphatic dicarboxylic, preferably having from 8 to 12 carbon atoms.

Particularly preferred examples of additional dicarboxylic acid components other than terephthalic acid, naphthanedicarboxylic acid, and 1, -cyclohexane dicarboxylic acid which are used include, but are not limited to, isophthalic acid, sulfoisophthalic acid, 1,3-ci acid carboxylic ohexandi, 1,4-cyclohexanediacetic acid, di-phenyl-, 4'-dicarboxylic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, 1,2-diodecandioic acid and dimeric acid. The copolyes teres can be prepared from one or more of the above dicarboxylic acids.

Branching Agents Small amounts, typically less than about 2 mol%, of conventional branching agents with the glycol component and the dicarboxylic acid component can be reacted to form the inventive copolyes. Conventional branching agents include polyfunctional acids, anhydrides, alcohols and mixtures thereof. Examples of suitable branching agents, include, but are not limited to, trimellitic anhydride, pyromellitic dianhydride, glycerol, trimethylolpropane, and pentaerythritol.

Reaction Process to Form the Copolés teres.

To form the copolyestof the invention, the reaction of the glycol component and the dicarboxylic acid component can be carried out using conventional polyester polymerization conditions. For example, when the copolyests are prepared by means of an ion exchange reaction, that is, from the ester to form the dicarboxylic acid components, the reaction process may comprise two steps. In the first step, the glycol component and the dicarboxylic acid component, such as dimethyl terephthalate, are reacted at elevated temperature, typically, around 180 ° C to about 280 ° C and pressures in the range from about 0.0 to about 60 psig (4.21 kg / cm2). Preferably, the temperature for the ester exchange reaction is in the range from about 190 ° C to about 240 ° C while the preferred pressure ranges are from about 15 psig (1.05 kg / cm2) to about 40 psig (2.81 kg / cm2). Then, the reaction product is heated under still higher temperatures and reduced pressures to form the polyester with the removal of the glycol, which volatilizes rapidly under these conditions and is removed from the system. The second step, or polycondensation step, is continued under high vacuum and at a temperature which is generally in the range from about 240 ° C to about 300 ° C, preferably around 250 ° C to about 290 ° C and more preferably around 270 ° C to about 285 ° C, up to a polymer having the desired degree of polymerization, determined by VI, which is obtained. The polycondensation step can be conducted under reduced pressure in the ranges from about 400 mm Hg- (torr) to about 0.1 mm Hg (torr). Without the help of an appropriate catalyst, the above reactions do not proceed at a remarkable speed.

To ensure that the reaction of the glycol component and the carboxylic acid component by an ester exchange reaction mechanism is carried to completion, it is preferred to employ 3 moles and more preferably about 2.3 to about 2.6 moles of a glycol component for a mol of dicarboxylic acid component. It will be undood that, however, the ratio of the glycol component to the carboxylic acid component is generally determined by the design of the reactor in which the reaction process occurs.

In the preparation of the polyester by direct esterification, that is, from the acid formed from the dicarboxylic acid component, the copolymare produced by the reaction of a dicarboxylic acid, such as terephthalic acid, napht alendicarboxylic acid, 1,4 -cyclohexanedicarboxylic acid, or mixtures thereof, with the glycol component. The reaction is conducted at a pressure of about 1 (0.070 kg / cm) to about 1000 pounds per square inch (70 kg / cm2) of measured pressure, preferably less than 100 psig (7 kg / cm2) to produce to produce a low molecular weight, the linear or branched polyester product having an average degree of polymerization from about 1.4 to about 10. The temperatures employed during the direct esterification reaction, typically range from about 180 ° C to about 280 ° C, more preferably in the range from about 220 ° C to about 270 ° C. This low molecular weight polymer can then be polymerized by a polycondensation reaction.

To ensure that the reaction of the glycol component and the dicarboxylic acid component by a direct esterification reaction mechanism is carried to completion, it is preferred to employ about 3.0 to 1.05 moles of a glycol component for one mole of dicarboxylic acid component . It will be undood, however, that the ratio of the glycol component to the dicarboxylic acid component can be determined by the design of the reactor in which the reaction process occurs.

The copolés teres of low V.l. they are generally obtained by using short residence times or slow time ranges compared to the processes to form copolyes teres with high V.l. For example, the reaction ratio can slowly reduce the reaction temperature, reducing the catalytic concentration, increasing the absolute pressure in the reactor or a combination of these factors.

The process for forming the copolyests of the invention can be conducted in a batch, semi-batch or continuous process. Advantageously the process is operated as a continuous process. Indeed, it is possible to produce a superior coloration of the copolyester when a continuous process is used, as the copolyester can deteriorate in appearance if the copolyester is allowed to be in the reactor at an elevated temperature for a very long duration.

Catalyst System A variety of catalyst systems are useful to promote the reaction of the glycol component and the dicarboxylic acid component. Typically, a catalyst system may contain catalytic materials and catalytic inhibitors.

Catalytic materials.

Catalyst materials that are suitable for the catalyst system include, but are not limited to, materials containing titanium, manganese, zinc, cobalt, antimony, gallium, lithium, calcium, silicon, and germanium. Indeed, such catalyst systems are described in US Patents 3,907,754, 3,962,189, 4,010,145, 4,356,299, 5,668,243, and 5,681,918, incorporated herein by reference. Generally, the catalyst system of the invention comprises materials containing titanium, manganese and / or zinc and mixtures thereof. While the amounts of the individual catalytic materials in the catalyst system may vary, it is desirable that the total amount of catalytic materials in the catalyst system be below 125 ppm, preferably below about 100 ppm and more preferably below about 80 ppm. . The "ppm" for the catalyst system and the catalytic inhibitor described below, refers to the weight of the referred element and is based on the theoretical weight of the final copolyester product.

The titanium catalytic materials are usually added in the form of an alkoxide in an amount in the range of from about 10 to about 35 ppm, more preferably from about 10 to about 25 and more preferably from about 12 to about 20 ppm. . Indeed, copolyes teres formed with low levels of titanium catalytic materials have better stability when kept in the melt. Suitable titanium alkoxides include, but are not limited to, acetyl triisopropyl titanium, t raisopropy 1 titanium and tet raisobutyl titanium. The titanium catalyst material can be added to the reaction process before the direct esterification or ester exchange reaction or before the polycondensation reaction.

The manganese is typically added in the form of a salt, such as an organic acid salt in an amount in the range from about 0 to 70 ppm, preferably about 30 to about 70 ppm and more preferably about 40 to about 50 ppm. Examples of suitable manganese salts include, but are not limited to, manganese benzoate tetrahydrate, manganese chloride, manganese oxide, manganese acetate, manganese acetylacetone, and manganese succinate. Manganese is added to the reaction process, before direct esterification or the ester exchange reaction.

Zinc can be added to the catalyst system in addition to manganese or instead of the manganese catalyst. Zinc is typically added in the form of a salt in an amount in the range from 0 to 100 ppm, preferably around 25 to about 100 ppm and more preferably around 50 to about 80 ppm.

Examples of suitable zinc compounds include, but are not limited to, zinc acetate, zinc phosphate monohydrate, zinc succinate, and zinc alkoxide. Zinc is typically added to the reaction process before direct esterification or ester exchange reaction.

If desired, a cobalt catalyst material can also be used as part of the catalyst system. When employed, cobalt is typically added in the form of a salt, such as an organic acid salt. Examples of suitable cobalt salts include, but are not limited to, cobalt acetate trihydrate, cobalt nitrate, cobalt chloride, cobalt acetylacetonate, cobalt naphthenate, and cobalt salicylate. Cobalt can be added in an amount in the range from about 0.0 to 90 ppm. As described below, cobalt can function either as a catalytic material and as a dye. The cobalt is added to the reaction process after direct esterification or ester exchange reaction.

In some modalities, antimony can be used. When used, examples of suitable antimony compounds include, but are not limited to, antimony esters of organic acids, antimony oxide, antimony alkoxides such as antimony isopropoxide, antimony halide, such as antimony chloride, bromide of antimony and antimony fluoride, sodium or potassium of antimony, antimony carboxylates, such as antimony acetate and antimony glycolate or mixtures thereof. Preferably the antimony component is an antimony glycolate or an antimony oxide. Antimony is usually added after the ester exchange or the direct esterification reaction. When the copolyester is used to form binder fibers, the antimony can be omitted from the catalyst system because it causes yellowing by the presence of a catalyst containing antimony.

Although less preferred, calcium, gallium and silicon catalytic materials can be used in the catalyst system. Examples of suitable calcium compounds include, but are not limited to, calcium acetate, calcium glycoxide, and calcium phosphate monohydrate. Examples of suitable gallium compounds are, but are not limited to, gallium chloride, gallium nitrate hydrate, gallium oxide, gallium lactate and gallium phosphide. Examples of suitable silicon compounds include, but are not limited to, silicon acetate and tetraethyl orthosilicate. Germanic catalytic materials include, but are not limited to oxides, organic salts and in particular germanium glycolates.

A preferred ester exchange catalyst system for reacting esters of terephthalic acid, naphthalenedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid contains materials of titanium, manganese, and optionally cobalt. In the ester exchange catalyst system, the titanium is present in an amount in the range from about 10 to about 35 ppm, preferably about 10 to about 25 ppm and the manganese is present in an amount in the range from around 30 to about 70 ppm. Additionally, in another embodiment of the ester catalyst system, the total amount of catalytic materials in the catalyst system is less than or equal to about 125 ppm, preferably less than about 100 ppm, more preferably less than about 80 ppm and more. preferably less than 70 ppm. A preferred ester catalyst system is typically used in combination with a catalytic inhibitor comprising about 40 to about 90 ppm P; and a dye in an effective amount, for example, from about 2 to about 10 ppm of a substituted blue and / or red anthraquinone dye. Generally, the preferred ester catalyst system is substantially free of Zn catalytic materials, more preferably it contains less than 5 ppm of Zn catalytic materials and more preferably is free of Zn catalytic materials. Additionally, when binder fibers are desired, the preferred ester catalyst system is substantially free of Sb catalytic materials, more preferably it contains less than 5 ppm of Sb catalytic materials and more preferably is free of Sb catalytic materials.

Catalytic inhibitor In order to stabilize the effects of the catalyst system and to efficiently promote the zinc, manganese and cobalt catalytic materials, it is desirable to add a phosphorus catalytic inhibitor to the reaction process after an ester exchange or direct esterification reaction but before driving the step of polycondensation reaction. Typically, the phosphorus is added in the form of a phosphate, such as phosphoric acid or an organic phosphate ester in an amount in the range from about 40 to about 90 ppm and more preferably in the range from about 60 to about 75 ppm. Suitable phosphate esters for use in this invention include, but are not limited to, ethyl acid phosphate, diethyl acid phosphate, triethyl phosphate, arylalkyl phosphates and tris-2-ethylhexyl phosphate. A useful phosphate catalytic inhibitor is sold under the Merpol® A brand that is commercially available from Du Pont.

Colorants To form the copolymers of the invention, the dyes (sometimes referred to as organic pigments) can be added to impart a desired neutral and / or glossy color to the resulting copolyester. When colored copolyes are desired, the pigments or dyes can be included in the reaction mixture during the reaction of the glycol component and the dicarboxylic acid component or can be dissolved mixed with the copolyester formed above. A preferred method for including colorants is to use a colorant having thermally stable organic colored compounds having reactive groups such that the colorant is copolymerized and incorporated into the copolyester to improve the hue of the copolyester. For example, dyes such as dyes possessing a reactive hydroxyl and / or carboxyl groups, including, but not limited to, blue and red substituted anthraquinones, may be copolymerized in the polymer chain. The dyes and dyes are described in detail in U.S. Patents 4,521,556, 4,740,581, 4,749,772, 4,749,773, 4,749,774, 4,950,732, 5,384,377, 5,372,864, 5,340,910 and 5,681,918, incorporated herein by reference. When the dyes are used as dyes, they can be added to the copolyester reaction process after the ester exchange or the direct esterification reaction. Furthermore, when a dye or dye mixture is used as the organic pigment dye for the copolyester, it is preferred that the total amount of the dye be less than 10 ppm.

Alternatively, inorganic pigments, such as titanium dioxide and cobalt-containing materials, can be added to the reaction. Advantageously when the catalyst material contains cobalt, the cobalt can act as a colorant. Care must be taken to control the cobalt level in order to avoid opacity and dull color in the copolyes teres of the invention. To control the level of opacity and dull color, cobalt can be used in an amount in the range from about 0.0 to 90 ppm.

Copoliés Teres de la Invención The copolyesters of the invention have an inherent viscosity, V.I., in the range from about 0.36 to 0.58. preferably the copolyests of the invention have a V.l. in the range from about 0.38 to about 0.58, more preferably around 0.4 to about 0.53, more preferably around 0.40 to about 0.50 and more preferably around 0.41 to about 0.49. V.l. of the copolyests of the invention is determined by measuring V.l. at 25 ° C using 0.5 g of polymer per 100 mL of a solvent consisting of 60% by weight of phenol and 40% by weight of t et racloroet anus. The basic method to determine V.l. of a copolyester is given in ASTM D-2857-70. Copies of teres produced with the values of V.l. low, they have excellent color and are lighter than the previous copolyes and can accept dyes more easily than copolyes with high V.l. In addition, the copiers are tere s with low V.l. They are easier to color at low temperatures and make it easier to print them than their high V.l. copolyester.

Similar. Additionally, since the copolyes of the invention have low V.I. values, the production ranges of the copolyes teres are quite rapid.

The polymerization of 1-cyclohexanedione with ethylene glycol and terephthalic acid can be controlled to form an amorphous polyethylene terephthalate polymer with a glass transition temperature similar to polyethylene terephthalate. As is known in the art, amorphous polymers generally have high clarity and do not opaque like many crystalline polymers. Therefore, while some of the 1, 4-cyclohexanedimethanol levels employed can form copolymers having some crystallinity, the superior clarity of the amorphous polyesters provides some distinct advantages.

Generally, a low V.l. copolyester It can have a low extrusion temperature. Therefore, the copolymers of the invention can advantageously be spun fused into fibers at a low temperature. For example, a copolyester of the invention with a V.l. of 0.47 can be spun fused at a temperature of about 233 ° C while a similar copolyester with a V.l. from 0.6 to 0.7 generally requires a spinning of fibers at a temperature of 275-285 ° C. Typically, a copolyester of the invention is spun at a temperature of less than about 250 ° C, in some cases at less than 235 ° C, which approximates the conditions used for spun polypropylene. These copolymers can be cast fused together with a row with about 32 holes and an orifice size of about 0.5 mm. Generally, melt spinning pressure can vary from about 1000 psig (70 kg / cm2) to 2000 psig (140 kg / cm2).

Typically, the clarity and color (hue) of the copolyes teres can be evaluated using a standard color spectacle. For example, a suitable color specimen for evaluating the clarity and color of the copolyester is a HunterLab UltraScan that is commercially available from HunterLab of Reston, Virginia. Through the use of a Huntercolor UltraScan imaging lens, clarity and color, that is, illamient and blueing, can be quantified. The use of a HunterLab UltraScan color-coded specimen to evaluate and quantify the color and clarity of a copolyester is disclosed in U.S. Patent 5,681,918, fully incorporated herein by reference. When using HunterLab UltraScan, an L * value indicates the level of clarity with high L * values representing high levels of clarity. The level of yellowing and / or blueing is quantified as a value b * with 0.0 of neutral representation, while values above 0.0 indicate levels of yellowing and values below 0.0 indicate levels of blueing in the copolyester. The copolyesters of the invention typically have an L * value of more than about 65, generally about 69 to about 72, and a b * value ranging from about -2.5 to about +2.5, preferably varying from about -1.0 to about +1.0, and more preferably in the range from about -0.5 to about +0.5 and more preferably about 0.0.

Products formed from Copoliés teres de la Invention The copolyesters of the invention can be used to form an article of manufacture or to be used as an additive, such as a concentrated additive compound or masterbatch for another polymer system. In addition, binder fibers and other articles can be formed with copolyesters including, but not limited to, plastics and films, including containers, molded parts, sheets and extruded films and fibers. The inventive copolyes can be parts of articles to be formed or they can form the entire article.

Conventional additives may be added to the copolymers of the invention, depending on the desired end used of the copolyester. Suitable additives for copolymers are described in detail in U.S. Patent Nos. 5,601,031 and 5,773,554 incorporated herein in full for reference. Typical additives for copolyes teres include pigments, antioxidants, stabilizers, flame retardants, hardeners, epoxies, mold release agents, core agents, radical free stabilizers, lubricants, and other processing agents.

A preferred article of the invention is a fiber. The fiber may be prepared in any desired length known in the art and generally in the form of a basic filament or fiber. The fibers can be made from the copolyes teres of the invention through any conventional means available including, but not limited to, melt spinning, melt blowing or extrusion of the copolyester in a fiber form. Depending on the end use, any desired denier can be formed with the fibers using copolyester of the invention, including fibers having a denier value in the range from a microdenier to about 50 denier, preferably up to about 20 denier.

The copolyes teres can be used to form binder fibers in any desired configuration known in the art. The copolymers of the invention are preferably binder fibers which have the form of a fibrous structure. A major advantage of the binder fibers is that the bonded products can be obtained by the single application by heat treatment, radio frequencies or ultrasound frequencies to a block of fibrous material or filaments with little or no change in shape. Indeed, the copolyests of the invention are particularly suitable for the use of binder fibers such as copolyesters having a low V.l. that allows better flow properties and smoothness at low temperatures. Therefore, the bonding improvement of the binder fibers is possible at lower temperatures than the previously known binding fibers for non-woven fabrics when binder fibers containing the copolyests of the invention are used. Indeed, the binder fibers formed from the copolyesters of the invention are particularly suitable for bonding polyester, acrylic, nylon, glass, cotton and carved wool. Typically, the binder fibers formed with the copolyesters of the invention may have deniers of from about 1.5 to about 20. However, other fiber shapes such as meltblowing or bonded yarns have many sizes of microdemanders.

The binder fibers of the invention may be in the form of unicomponent binder fibers and bicomponent liners or other surface segments formed with the copolyesters of the invention having a V.l. from around 0.36 to around 0.58. The forms of binder fibers can be formed with the upper portions of the transverse legs in section covered with binder materials during extrusion.

Bicomponent binder fibers may have a liner / core, side by side, or other configuration known in the art. The process for preparing a link to a bicomponent low melting temperature binder fiber is described in detail in U.S. Patent 3,589,956, fully incorporated herein by reference. In the bicomponent fiber of the invention, the copolyesters of this invention can be present in amounts of from about 10 to about 75% by weight of the bicomponent fiber. The other component can be formed from a wide range of other polymeric materials including, but not limited to, polyesters such as polyethylene terephthalate or polybutylene terephthalate. Bicomponent binder fibers can be blended with other fibers or used alone to make non-woven fabrics and blocks of superior fibrous materials having various properties. Generally, bicomponent binding fibers contain a polymer having a high melting point to ensure its structural integrity during the bonding process and a low melting or amorphous polymer to bond the matrix in the non-woven fabrics. Alternatively, economic reasons may dictate that a much less expensive core material should be used.

The binder fibers of this invention are easily bonded with a wide range of other fibers and subsequently heated or energized to provide non-woven fabrics having good integrity and strength. For example, other fibers in the blends may include, but are not limited to, polyester, acrylic, nylon, glass, cellulosic (cotton, pulp based fibers, cellulose ester fibers etc.) and other similar fibers. The incorporation in nonwovens can also help the lamination of other fabrics, films and some metallic surfaces. The amount of binder fiber in the nonwoven blend should generally be in the range of from about 5 to about 30% by weight; however, this is an example where 100% bonded fibers are used in the manufacturing form.

Other fibrous structures that can be made with the copolyesters of the invention is a composite fiber that can be formed by melt spinning of a polyolefin or a functional polyolefin with the copolyester of the invention. The copolyester / polyolefin melt spun yarn can be spun as a fiber to form a fibrous structure.

The fibrous structures of the invention are particularly useful for processing in a wide variety of non-woven, woven and quilt fabrics for a variety of applications, but are particularly suitable for the manufacture of bound and non-quilted textiles and nonwovens, whether padded or non-quilted , which can act by a variety of means. These are also suitable for use in the preparation of a wide variety of products including, but not limited to, blocks of superior fibrous material, needle-punched fabrics, non-woven uniforms, hydroentagel fabrics, fabrics bonded by stitches (to minimize stacking), non-woven wet laid fabrics and paper, filter media, face masks, dissipated carpets, cotton rugs, cellulosic insulation, absorbent products, fiberglass compositions, pillow stuffing, sleeping bag fillers, cushions , quilts, quilts, bedspreads, mattresses, mattress fillings, mattress linings, furniture and car upholstery, bedspreads, pile fabrics for industrial use and clothing, blankets, women's coats, casual bags, car covers, interlinings, outer clothing, materials to cover the floor, linings, rugs, sandals for bath, laces and molded articles.

Other suitable uses for the copolyesters of the invention is a copolyester carrier material. For example, the copolyester of the invention can be mixed with colorants or additives to form a copolyester carrier material which can then be compounded with another polymer. The copolyesters can be mixed or bound by any suitable technology known in the art.

Examples Example 1 Copolyesters of Low Catalyst, Low V.l. for Binding Fibers.

A comparison was made between the copolyesters formed with a V.l. of 0.59 and a low V.l. of 0.47. the copolyester formed with V.l. higher than 0.59 was made using a catalyst system with a high concentration of catalytic materials. In contrast, copolyesters formed with low V.l. of 0.47 were formed using a catalyst system having a low concentration of catalytic materials.

The low copolyester V.l. containing about 31 mol% of 1-cyclohexanedimethylene and about 69 mol% of ethylene glycol was prepared from 1,4-cyclohexanedimethanol, ethylene glycol and dimethyl terephthalate. The reaction was conducted with an excess of glycol component. The reaction proceeded first by conducting an ester exchange reaction step followed by a polycondensation reaction step. The ester exchange reaction was conducted at a temperature in the range from 190 ° C to 240 ° C and a pressure of 15 (1.05 kg / cm2) to 40 psig (2.81 kg / cm2) in the presence of a catalyst system containing 16 ppm Ti (as titanium tetraisopropyl) and 46 ppm Mn (as manganese acetate). The product of the ester exchange reaction was subjected to a polycondensation reaction step where the initial temperature was from 250 ° C to 260 ° C and the final temperature was from 269 ° C to 282 ° C. In the same way the pressure of the polycondensation reaction started at 75 to 200 torr and ended at 0.3 to 2.5 torr. Before starting the polycondensation step, less than about 10 ppm of a mixture of blue and red anthraquinone dyes was added to the catalyst system and a catalytic inhibitor comprising Du Pont's Merpol A was added in an amount from about 70 ppm D.E.P.

The copolyester of high V.I., V.l. of 0.59, it was prepared to have the same composition as the low V.l. copolyesters. As with the copolyesters of low V.I., the reaction proceeded by first conducting an ester exchange reaction step followed by a polycondensation reaction step. The ester exchange reaction was conducted at a temperature in the range from 190 ° C to 240 ° C and a pressure of 15 (1.05 kg / cm2) up to 40 psig (2.81 kg / cm2) in the presence of a catalyst system containing 56 ppm Ti (as titanium sopropyl tea) and 46 ppm Mn (as manganese acetate). The product of the ester exchange reaction was subjected to the polycondensation reaction step where the initial temperature was from 250 ° C to 260 ° C and the final temperature from 275 ° C to 285 ° C. The pressure of the polycondensation reaction started at 75 to 200 torr and ended at 0.3 to 2.0 torr. The use of a long reaction time was required to obtain the copolyester with higher V.l. Before starting the polycondensation step, 56 ppm of cobalt acetate was added to the catalyst system and 79 ppm of a catalytic inhibitor comprising Merpol A from Du Pont was added.

A HunterLab UltraScan spectrocolorimeter was used to evaluate and quantify the color and clarity of the three copolyesters.

TABLE 1 As evident from Table 1, the copolyesters of low V.l. formed with systems of low catalytic concentration have superior clarity and color.

Example 2 Bond Strength for Binding Fibers Made with Copolyesters of Low and High V.l.

Co-polyester pellets having a V.l. of 0.47 and containing about 31 mol% of 1,4-cyclohexanedimethanol and about 69 mol% of ethylene glycol were prepared from 1,4-cyclohexanedimethanol, ethylene glycol and dimethyl terephthalate under reaction conditions similar to those of Example 1. The catalyst system used to form low Vl pellets contained 35 ppm of Ti (as t-raisopropyl titanate) and 46 ppm of Mn (as manganese acetate), 50 ppm of cobalt acetate while the catalytic inhibitor comprised Du Pont's Merpol A in an amount of 70 ppm of P.

The copolyester pellets of V.l. of 0.47 were dried in a rotary dryer at 65 ° C for 4 hours. The unicomponent binder fibers are formed from low and high V.l. copolyester pellets. melting by extrusion the pelleted fibers in many filaments of 9 denier / filament. The filaments were formed using a spinner having 332 holes (0.55 mm per hole), a melting temperature of 233 ° C and taking a speed of 100 m / m. the copolyester pellets of V.l. of 0.59 of Example 1, were formed in the same way in unicomponent binder fibers, except that the pellets were spun at a melting temperature of 275 ° C.

The fibers thus spun were passed through the looms of a loom subsequently in a 2-stage process (water at 70 ° C, followed by a heating chamber), total drafting ratio 3: 1, and a filler machine box corrugated 7 undulations / inch and a corrugation angle of 88. The resultant 3 denier fiber was then lubricated with a water base finish and dried in an oven.

Both of the unicomponent binder fibers are low V.l. copolyester. of 0.49 and high V.l. of 0.59 were combined with 75% polyethylene terephthalate fibers to form non-woven fabrics of intimately mixed cord of 3 oz / yard2 (101.64 g / m2). The non-woven fabrics were activated and subjected to a bond strength test by bonding the non-woven intimately mixed in a press, with the upper and lower trays heated in contact with the non-woven with pressure. It is active for 30 seconds at a temperature range from 200 to 275 ° F (93 to 135 ° C). A 1-inch metal band was used to obtain an Instron tensor to a 5-inch-gauge length. The results of the link strength tests are presented in detail in Table 2 below.

Table 2 Non-Woven PET / Uni Samples -Component Similar tests were conducted with a bicomponent cover / co-extruded core binder fiber, having 35% of a copolyester binder cover of a V.l. of 41 and 65% of a core of polyethylene terephthalate having about 4 denier. Similar results were obtained.

Example 3 Bond Strength Test of Bonding Fibers.

Unicomponent binder fibers were formed from terephthalate copolyester containing 31 mol% of 1, -cyclohexanediminol, 69% ethylene glycol and a dicarboxylic acid component containing 100 mol% of dimethyl terephthalate.

A first unicomponent binder fiber was formed from a first copolyester which was formed in the presence of a catalyst system having a low level of catalytic materials. For the first copolyester, an ester exchange reaction step occurred in the presence of a catalyst system containing 35 ppm Ti (as titanate of te t rai sopropi) and 46 ppm of Mn (as manganese acetate). Before starting the polycondensation step, 50 ppm of Co (as cobalt acetate) was added to the catalyst system and a catalytic inhibitor comprising Du Pont Merpol A in an amount of 70 ppm of P was added. The first copolyester was formed with a Vl of 0.47 and owned a denier up to 3.

A second unicomponent binder fiber was formed from the copolyester pellets of Example 1, having a V.l. of 0.47. The copolyester pellets of a V.l. of 0.47 of Example 1 were formed in the presence of a low concentration catalyst system. The second unicomponent binder fiber had a denier up to 3.

The first and second unicomponent binder fibers were combined with polyethylene terephthalate fibers having from a denier to 6 to form a non-woven manufacture. The binder fiber comprises 25% of the nonwoven manufacture with the polyethylene terephthalate comprising the other 75%. The non-woven web contained activated binder fibers and subjected to bond strength tests by the procedures described in Example 2, above, except that the upper and lower trays were spaced apart to allow a touch of contact, without any pressure recorded in the pressure measurement. The results of the link strength tests are shown in the following Table 3.

Table 3 Non-woven Fabrics w / Second Co-Polyester Binding Fibers Temperature Elongation Strength Modulation of Activation Break Average, Average, g ° F Average, g As shown in Table 3 above, the use of different levels of catalyst materials within the scope of the invention does not appear to significantly affect the bond strength of binder fibers made with similar intrinsic viscosities.

Example 4 The unicomponent binding fibers were formed from copolyesters containing 31 mol% of 1,4-cyclohexandime t anol, 69% ethylene glycol and a dicarboxylic acid component containing 100 mol% of dimethyl terephthalate. A first unicomponent binder fiber was made from the second low catalyst and low V.l. copolyester. of Example 3. A second unicomponent binder fiber of the copolyester of Example 1 was made having a V.I of 0.59. Both first and second unicomponent fibers were made by the processes described in Example 2. The non-woven fabrics of intimately mixed cards were made from the first and second binding fibers by the process described in Example 2. The bond strength tests were performed in a manner similar to that described in Example 3. The results of the link strength tests are presented below in Table 4.

Table 4 As shown in Table 4, the binder fibers formed with the V.l. lowest of 0.47 had the highest bond strength at lower activation temperatures.

Example 5 Low Vicosity PET Copolyester Containing 30/70 of a cis / trans mixture of 1,4-cyclohexanedimethanol.

A polyethylene terephthalate copolyester was formed from a glycol component and a carboxylic acid component. The glycol component contained 31 mol% of a 30/70 cis / trans mixture of 1,4-cyclohexanedimethanol, and 69 mol% of ethylene glycol. The dicarboxylic acid component comprises 100 mol% dime thi 1 terephthalate. The polyethylene terephthalate copolyester was prepared by melt phase polycondensation process using a catalyst system containing 32 ppm Ti, 46 ppm Mn, 50 ppm Co and 70 ppm P. The polyethylene terephthalate copolyester formed had a V.l. of 0.50.

The pellets of this copolyester were dried at 60 ° C for 2 hours and then melted by extrusion into fibers of 9 filaments of 9 denier / filament using a spinner having 332 holes (0.55 mm hole) taking a speed of 1000 m / m , a melt spinning temperature of 240 ° C and an extrusion ratio of 43 pounds per hour (19,522 kg / hour). A speed of 145 cubic feet per minute (4.10 m / minute) was used to quench the filaments during extrusion. The fused fibers were passed through the looms of the loom subsequently in a one-step drawing process using a 68 ° C water bath. The polymeric fibers were corrugated in a filler machine to provide 7.5 undulations per inch and a 90 degree corrugation angle using an established 9.5 psi (0.67 kg / cm2) gauge without flow. The fiber was dried in a relaxed state at 60 ° C for 2 minutes. The resulting basic fiber was determined to have 3 deniers per year.

The good results were similarly performed when the copolyester was not dried before the spinning operation.

The fibers were also rapidly produced from PET copolyesters containing 22 mol% of CHDM (V.l. 0.40) or 45 mol% of CHDM (V.l 0.49).

Example 6 Preparation of the Nonwoven Net.

The one-component binder fiber of Example 5, 3 denier per filament, was mixed with the basic fibers of polyethylene terephthalate (2 1/4 denier per filament) to improve a mixture containing 20% by weight of binder fiber. A nonwoven network intimately mixed 1 1/4 oz / yard (42.35 g / m) was formed by carding. The nonwoven web was connected by convection of the network through an infrared oven, followed by hot clamping (80 ° C). Good maquilación and strength of direction of crossed and movable direction were obtained.

A good bond was also obtained by passing the card network through an air flow through an oven at 150 ° C for two minutes of time.

The binder fibers of the composition of this invention were determined by radio frequency and activatable ultrasonic.

Example 7 Preparation of a Bright Colored Non-woven Net.

A 1-1 / 2 oz / yd2 (50.82 g / m2) fabrication occurred in a manner similar to Example 6; however, the polyester matrix colored red. The clear, non-opaque bonds were provided by the unicomponent binder fiber of Example 5 minimally affecting the brightness of the shape. This is an advantage over the modified isophthalic polyethylene terephthalate copolyester binding fibers which are generally more opaque and often contribute to a very cold, hazy appearance in the colored articles.

E xemployment 8 Fiber Bicomponent Lining / Core A 50/50 liner / core bicomponent fiber was made using a homopolymer of polyethylene terephthalate (V.l. 0.54) as the core and a polyethylene terephthalate copolyester similar to that of Example 5 (V.l. 0.41) as the liner. The bicomponent fiber was formed as follows: crystallized, dry PET pellets were melted in an extruder and fed as the core at a melting temperature of 295 ° C. The dry copolyester PET pellets were transported to the extruder feeder feeding the melt flow. The liner flow was extruded to a melting temperature of 225 ° C. The melt flows are coextruded through a yarn having a liner / core hole configured for melting ranges adjusted to produce fibers having a 50% polyester / 50% core PET liner. A similar 35/65 liner / core bicomponent fiber was also produced in filament and basic form. The figures were drawn with drawing roll speeds to produce fibers of 4 denier per filament which were then corrugated and cut into basic fibers (51 mm long).

These bicomponent binder fibers are useful for making nonwoven fabrics and top batts (cotton sheets) in combinations with polyethylene terephthalate and / or other basic matrix fibers. These binder fibers are also used in 100% forms.

It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional to which it refers.

Having described the invention as above, the content of the following is claimed as property.

Claims (28)

Claims

1. A binder fiber, characterized in that it comprises a copolyester formed from the reaction product of: a glycol component with a dicarboxylic acid component, wherein the glycol component comprises 1,4-cyclohexandime t anol in an amount in the range from about 10 to about 60 mol% and ethylene glycol in an amount in the range from about 40 to about 90 mol%, in wherein at least about 90 mole% of the dicarboxylic acid component is selected from the group consisting of acids, esters and anhydrides of terephthalic acid, naphthalene carboxylic acid, 1,4-cyclohexanedi carboxylic acid and mixtures thereof, and wherein the copolyester has a Vl from around 0.36 to 0.58.

2. The binder fiber of claim 1, characterized in that at an activation temperature of less than about 275 ° F (135 ° C), the binder fiber possesses an upper bond strength compared to a binder fiber formed from a copolyester which has a Vl of 0.6 or higher.

3. The binder fiber of claim 1, characterized in that the binder fiber can be activated by ultrasonic and radio frequencies.

4. The binder fiber of claim 1, characterized in that the binder fiber has a denier in the range from about 1 to about 20.

5. The binder fiber of claim 1, characterized in that the binder fiber is a unicomponent binder fiber.

6. The binder fiber of claim 1, characterized in that the binder fiber is a bicomponent binder fiber.

7. A copolyester comprising the reaction product of: a glycol component with a dicarboxylic acid component, characterized in that the glycol component comprises 1,4-cyclohexanedimethanol in an amount ranging from about 10 to about 60 mol% and ethylene glycol in an amount in the range from about 40 to about 90 mol%, wherein at least about 90 mol% of the dicarboxylic acid component is selected from the group consisting of acids, or esters or anhydrides of terephthalic acid, naphthalenedi carboxylic acid, 1,4-cyclohexanedicarboxylic acid and mixtures thereof, and in where the copolyester has a Vl between about 0.36 to 0.58 and an L * value of more than about 65.

8. The copolyester according to claim 7, characterized in that the value L * is greater than about 65 and the value b * is in the range from about -2.5 to about +2.5.

9. The copolyester according to claim 7, characterized in that the dicarboxylic acid component is an ester or a mixture of esters of terephthalic acid, naphthanedicarboxylic acid, or 1,4-cyclohexanedicarboxylic acid.

10. The copolyester according to claim 7, characterized in that the copolyester is formed in the presence of a catalyst system comprising about 10 to about 35 ppm of Ti, about 30 to about 70 ppm of Mn, about 0 to about of 90 ppm Co and in the presence of a catalytic inhibitor comprising about 40 to about 90 ppm of P based on the weight of the copolyester.

11. The copolyester according to claim 7, characterized in that it further comprises an additional dicarboxylic acid component in an amount of more than 10 mol% of the dicarboxylic acid component, wherein the additional dicarboxylic acid component is selected from the group consisting of acids aromatic dicarboxylics having from about 8 to about 14 carbon atoms, aliphatic dicarboxylic acids having from about 4 to about 12 carbon atoms, cycloaliphatic dicarboxylic acids having from about 8 to 12 carbon atoms and esters or anhydrides from the same.

12. The copolyester according to claim 7, characterized in that the glycol component comprises 1,4-cyclohexanedimethylene in an amount in the range from 20 to 40% mol and ethylene glycol in an amount in the range from about 60 to about 80% mol.

13. The copolyester according to claim 7, characterized in that the glycol component comprises 1,4-cyclohexanedimethylene in an amount in the range from 25 to 35% mol and ethylene glycol in an amount in the range from about 65 to about 75% mol.

14. The copolyester according to claim 7, characterized in that the glycol component contains diethylene glycol in an amount of more than 20 mol%.

15. The copolyester according to claim 7, characterized in that the value of V.l. It is in the range from around 0.41 to 0.49.

16. The copolyester according to claim 7, characterized in that the copolyester is formed in the presence of a branched agent.

17. The copolyester according to claim 7, characterized in that the copolyester is capable of being spun by melting in a fiber at a temperature of less than about 270 ° C.

18. A copolyester composition, characterized in that it comprises the copolyester of claim 7 and an additive selected from the group consisting of a pigment, a dye, a stabilizer, an antioxidant, an extrusion aid, a starting agent, carbon black, a core agent, a flame retardant, a filler, a conductive material, an adhesion promoter, a hardener, a viscosity modifier, a dye promoter and mixtures of the same.

19. The copolyester according to claim 7, characterized in that the copolyester is in fibrous form.

20. The copolyester of claim 19, characterized in that the fibrous form of the copolyester has a denier in the range from 20 to microdenier size.

21. A fibrous structure, characterized in that it comprises forming a fiber by fusion bond of a polyolefin or a functional polyolefin with the copolyester of the claim 7.

22. A copolyester comprising the reaction product of: a glycol component with a dicarboxylic acid component, characterized in that the glycol component comprises 1, -cyclohexanedylenol in an amount ranging from about 10 to about 60 mol% and ethylene glycol in an amount ranging from about 40 to about 90 mol%, wherein less about 90 mol% of the dicarboxylic acid component is selected from the group consisting of acids, or esters or anhydrides of terephthalic acid, naft alene carboxylic acid, 1,4-cyclohexanedicarboxylic acid and mixtures thereof, and wherein the copolyester is formed in the presence of a catalyst system comprising about 10 to about 35 ppm Ti and wherein the copolyester has a Vl from around 0.36 to 0.58.

23. A catalyst system for producing a copolyester, characterized in that it comprises: a catalytic material comprising from about 10 to about 35 ppm of Ti and from about 30 to about 70 ppm of Mn, wherein the total amount of catalytic materials in the system catalyst is less than or equal to about 125 ppm; a catalytic inhibitor comprising about 40 to about 90 ppm of P; Y an effective amount of a dye or other than cobalt to produce the desired color; and wherein the amounts of the components of the catalyst system are based on the weight of the copolyester product formed with a catalyst system.

24 The catcher system of claim 23, characterized in that the total amount of catalytic materials in the catalyst system is less than 100 ppm.

25. The catalyst system of claim 23, characterized in that the aliquator cat is substantially free of Sb and Zn catalysts.

26. The copolyester of claim 7, characterized in that it is melt bonded to another polymer.

27. A fibrous structure, characterized in that it comprises forming it from the fusion bond of the copolyester of claim 7 and another polymer.

28. An additive, characterized in that it comprises the fusion bond of the copolyester of claim 7 and a first polymer, wherein the additive when mixed with a second polymer is capable of forming a fiber and wherein the first and second polymers can be the same polymer. COPOLYMER FIBERS, IMPROVED AGGLUTINANTS Summary 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 of 1,4-cyclohexanedimethanol, ethylene glycol and terephthalic acid, naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid and esters or anhydrides thereof. Such copolyesters can be formed into a variety of products, especially binder fibers for non-woven fabrics.