US3511801A - Process of preparing polyester fibers - Google Patents

Description

United States Patent 3,511,801 PROCESS OF PREPARING POLYESTER FIBERS Richard Young Meelheim, Kinston, N.C., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware No Drawing. Continuation-impart of application Ser. No. 355,934, Mar. 30, 1964, which is a cOntinuation-in-part of application Ser. No. 273,832, Apr. 18, 1963. This application Mar. 30, 1967, Ser. No. 626,974

Int. Cl. C081? 45/34, 45/06; C08k 1/36 U.S. Cl. 260-30.8 3 Claims ABSTRACT OF THE DISCLOSURE A process is disclosed for preparing polyester textile fibers having improved surface luster and friction properties. The polyester is prepared by conventional ester interchange-polymerization of dimethyl terephthalate With ethylene glycol to form polyethylene terephthalate, which is melt spun in conventional manner. Prior to completion of the polymerization, from 0.25% to 10% by weight Cross-references to related applications This is a continuation-in-part of my copending application Ser. No. 355,934, filed Mar. 30, 1964, now-abandoned, as a continuation-in-part of my application Ser. No. 273,832, filed Apr. 18, 1963, now abandoned.

This invention relates to improved textile products, such as yarns, filaments, and fibers, and to fabrics prepared therefrom. More particularly, it relates to an improved method of preparing synthetic polyester textile fibers possessing desirable luster and friction properties.

Melt-spun polyester filaments are characterized by a smooth surface which gives high yarn running friction, high static friction and high surface luster. Attempts have been made to reduce friction and luster by special sizing treatments or other surface coatings and by adding finelydivided inert materials to the polymer before spinning. Neither approach has been completely successful. For example, the addition of many finely-divided inert materials to the molten polymer, in amounts sufiicient to reduce friction, leads to the plugging of filter packs in the meltspinning operation with a consequent reduction in efficiency of operation. On a commercial scale, the reduction in efiiciency has been prohibitive. Furthermore, the presence of many inert materials leads to an excessive reduction in maximum yarn strength. Reduced luster has been achieved by adding pigments such as titanium dioxide, but Ti0 also increases fiber opacity, which in many instances is undesirable.

3,51 1,801 Patented May 12,- 1970 It is an object of this invention to provide for the preparation of synthetic polyester textile fibers having reduced surface luster. A further objective is the preparation of melt-spun polyester fibers exhibiting reduced running and static friction. A corollary objective is to provide for incorporation of an inert material in a polyester fiber without significant loss of strength in the fiber. A still further ob ect is the provision of a procedure for incorporating relatively large amounts of a finely-divided inert material in a polyester fiber without encountering excessive packplugging during melt-spinning.

These and other objectives are achieved in a process for preparing synthetic linear condensation polyester textile fibers which comprises adding to the monomer, or to low molecular weight polymer, a glycol slurry of (1) thin, hexagonal platelets of Al O -2SiO -2H O having the kaolinite crystal structure, with particle sizes in terms of equivalent spherical diameters falling in the range 0.27 microns and with (E.S.D.) values, defined below, falling in the range 1-5 microns, combined with (2) from 0.2 to 5.0% by weight, based on weight of kaolinite, of a heat-stable glycol-soluble organic defiocculating agent selected from the group consisting of (A) condensation products of ethylene oxide and fatty alcohols containing 9 to 30 ethylene oxide units per molecule, (B) condensation products of ethylene oxide and substituted phenolic compounds having 9 to 30 ethylene oxide units per molecule, (C) alkali metal salts of alkylarylsulfonic acids, and (D) ditertiary acetylenic glycols of the formula where R and R are alkyl groups having 1 to 4 carbon atoms, and ethylene oxide condensates thereof. The resulting mixture is polymerized to give a synthetic linear condensation polyester having an intrinsic viscosity of at least 0.3 which is subsequently melt-spun and drawn to give a textile fiber.

By this procedure, fibers containing up to 10% by Weight of kaolinite may be prepared readily. For most textile purposes, it is preferred that the fibers contain from 0.25 to 3.0% by weight of kaolinite.

The above process produces a drawn synthetic linear condensation polyester fiber having randomly dispersed therein hexagonal platelets of kaolinite oriented roughly parallel to the fiber axis. Microscopic inspection reveals that each platelet is surrounded by an elongated void Where the polymer has separated from the particle and that the fiber surface exhibits slight protrusions and hollows. The filaments show a subdued surface luster, but not the gross reduction in transparency characteristic of simi-v lar yarns containing equivalent amounts of TiO Standard friction tests indicate a marked reduction in both dynamic and static frictional properties. Fiber strength is substantially equal to that of otherwise similar fibers containing no kaolinite.

The fibers produced by the process of this invention show reduced and more uniform running tensions, with greatly improved. performance in mill processing, i.e., ;pooling,..-twisting,. quilling, and weaving. Fabric prepared "rom these fibers shows a more uniform fabric structure, fewer streaks or flashes and less barr.

By adding various quantities of conventional TiO deustrant in the above process, it is possible to achieve a vide variety of combination of surface luster and opacity. 3y proper choice of the kaolinite/TiO ratio, the polyester {am manufacturer is now able to prepare yarns with ;ubtle luster eifects hitherto unobtainable in a commercial arocess.

Hexagonal platelets of aluminum silicate having the caolinite crystal structure are described by C. E. Marshall n The Colloid Chemistry of the Silicate Minerals, Acalemic Press, Inc., New York, N.Y. (1949), pages 49 and 72. For the purposes of this invention, it is necessary to ise a highly purified kaolinite which is substantially free if oxides of metals other than aluminum and silicon. It s further necessary to use a kaolinite in which the par- :icles have equivalent spherical diameters in the range ).2 to 7 microns and an (E.S.D.) value in the range 1 :o microns. The term equivalent spherical diameter refers to the diameter of an imaginary sphere having the tame volume as the kaolinite particle, and may be cal- :ulated from measurements made on electron-micrographs 3f particlesor from conventional sedimentation measurements. The (E.S.D.) value is that equivalent spherical diameter which is exceeded in size by just 10% by Weight of the particles measured. (E.S.D.) is specified in preference to average particle size since it gives better control of that portion of the kaolinite sample having the larger particle size range. This is important because the larger particles have the greater effect upon surface roughening, pack plugging and yarn strength loss.

The presence of even small quantities of particles having an equivalent spherical diameter larger than about 7 microns not only results in an appreciable drop in maximum fiber tenacity but also produces plugging of filter packs in the melt-spinning operation. On the other hand, particles smaller than about 0.2 micron do not give the filament surface-roughening effect which is necessary for reduced running tensions.

In order to insure that kaolinite of the proper particle size range is incorporated in the polymer, highly refined commercial grades of the desired nominal particle size are first suspended in glycol along with certain preferred deflocculating agents defined below. The glycol slurry is mixed, e.g., by ball'milling for at least 16 hours, and then stirred for at least 2.4 hours to insure complete defioc culation of the kaolinite particles. It is preferred that the glycol slurry be continuously stirred until injected into the polymerization system.

The deflocculating agent mentioned above, which must be added at a concentration of at least 0.2% by weight based on weight of kaolinite, must be capable of deflocculating kaolinite in the glycol slurry and maintaining the kaolinite in a deflocculated condition throughout the polyesterification process. Otherwise, there is an undue rise in pack pressure ('e.g., see'Example IXa). It must be stable at polyesterification temperatures, cause no polymer degradation orv discoloration, and have no adverse effect on polymerizationrates. 'It has .beenfound that these conditions are met bya highly. restricted group of organic reagents having a good balance between oleophilic and hydrophiliccharacterv and being free of combined nitrogen. The preferred reagents in this group are as follows:

(A) Condensation products of ethylene oxide and fat ty alcoholshaving 8 to 25 carbon atoms. Suitable alcohols useful in the preparation of these condensates include oleyl alcohol, decyl alcohol, lauryl alcohol, cetyl alcohol, and stearyl alochol. The condensate should have 9 to 30 ethylene oxide units per molecule for best results.

(B) Condensation products of ethylene oxide and sub stituted phenolic compounds. The "phenolic hydroxyl may be attached to a benzene, naphthalene, or diphenyl nu cleus, and the nucleus may be monoalkylated, dialkylated, or polyakylated, with side chains having 5 to 20 carbon atoms. Suitable substituted phenolic compounds include nonylphenol, p-tert-octylphenyl, iso-octylphenol, diamylphenol, 6-nonylnaphthol-2, dodecylphenol, 6-iso-propyl naphthol-Z, ethylphenylphenol, isobutylphenol, and dinonylphenol. The phenolic compound should be combined with 9 to 30 ethylene oxide units per molecule.

(C) Alkylarylsulfonates of the alkali metals. Suitable alkylarylsulfonates include sulfonated naphthalene and benzene nuclei to which are attached aliphatic groups having 3 to 20 carbon atoms. Examples of such reagents are ethylphenylphenol potassium sulfonate, dodecylbenzene sodium sulfonate, diisopropylnaphthalene sodium sulfonate, sodium alkylnaphthalene sulfonate (alkyl is prop ylene tetramer), and dibutyl naphthalene sodium sulfo' nate. Either sodium, lithium, or potassium salts are suitable.

(D) Ditertiary acetylenic glycols of the formula where R and R are alkyl groups having 1 to 4 carbon atoms, and ethylene oxide condensates thereof. Examples of suitable reagents of this type include 3,6-dimethyl-4- octyne-3,6-diol, 2,4,7,9-tetramethyl-S-decyne-4,7-diol and 4,7-dimethyl-5-decyne-4,7-diol. The ethylene oxide condensates of these reagents may contain up to by weight of ethylene oxide.

The presence of a defloccnlating agent from the group described is even more critical in situations where both titanium dioxide and kaolinite particles are added to the same polymerization system. The combination of TiO;, and kaolinite, especially when added in the same slurry, appears to be exceptionally susceptible to agglomeration unless the proper deflocculating agents are present.

The prepared kaolinite slurry is incorporated in the polymer by adding it to suitable polyester-forming reactants at the beginning of the polymerization, or at some later point during the polymerization procedure. Preferably, the slurry is added after polymerization has started, but before an appreciable viscosity change has been realized. In the ester interchange-polymerization procedure of Whinfield and Dickson, US. Pat. No. 2,465,319, it is preferred that the glycol slurry be added after ester interchange has been completed but before the intrinsic viscosity level of the polymer has reached 0.1.

Following addition of the slurry to the polymerization mixture, the process is carried out in the conventional manner to give a fiber-forming high polymer. The polymer formed may be forwarded in the molten state through conduits to a spinning machine and there melt-spun into filaments which are subsequently drawn to give strong textile fibers. Alternatively, the polymer may be extruded as a ribbon, quenched, cut to flake and subsequently remelted for spinning into textile fibers on conventional melt-spinning equipment. a

The above procedure of adding kaolinite particles to polyesters gives the yarn manufacturer good control of yarn luster and frictional properties. However, the presence of kaolinite also causes an increase in the concentration of ether linkages in the polymer, and higher concentrations of ethers are known to lower the melting point as well as make the polymer more sensitve to hydrolysis and to degradation upon exposure to light. For those end uses where a low ether content is desirable or necessary, ether'formation may be prevented or reduced by adding to the polymerization system as an ether inhibitor a minor amount of a noncolored, soluble base. Preferably, the base is added in the amount of 0.001-0.10% by weight based upon total weight of the monomeric unit. In the case of polyethylene terephthalate,'this is equivalent to basing the weight percent of base on the weight of dimethyl terephthalate in the initial charge.

By base is meant a metal compound which, when dissolved in water, increases the concentration of hyadroxyl ions. Suitable bases include the hydroxides, acetates, formates and carbonates of the alkali and alkaline earth metals. A preferred compound is sodium acetate. Non-colored bases are used to avoid tinting the polymer. Bases soluble in the polymerization mixture are used to provide the maximum ether inhibition effect at minimum concentration levels, and to avoid the cloudiness associated with dispersed insoluble materials.

The term synthetic linear condensation polyester, as used herein, comprehends a substantially linear polymer of fiber-forming molecular weight comprising a series of predominantly carbon atom chains joined by a recurring carbonyloxy radical,

o As used herein, the term polyester is intended to include copolyesters, terpolyesters and the like. Included, for example, are the polyesters disclosed in US. Pats. Nos. 2,465,319, 2,901,466 and 3,018,272. Polyesters having an intrinsic viscosity of at least about 0.3 are considered to be of fiber-forming molecular weight. Intrinsic viscosity has been defined in US. Pat. No. 3,057,827.

Dibasic acids useful in the preparation of polyesters and copolyesters of this invention include terephthalic acid, isophthalic acid, sebacic acid, bibenzoic acid, hexahydroterephthalic acid, ethylenedibenzoic acid, isopropylidinedibenzoic acid, 4,4'-dicarboxydiphenyl ether, 4,4"-dicarboxy-m-terphenyl, 2,6- and 2,7-naphthalenedic-arboxylic acid. Glycols useful in the preparation of the polyesters and copolyesters of this invention include the polymethylene glycols such as ethylene glycol and tetramethylene glycol and branched chain glycols such as 2,2- dimethyl-1,3-propanediol and 2,2-dimethyl-1,4-butanedio1. Also included are cisand trans-hexahydro-p-xylylene glycol, bis-p-(2-hydroxyethy1)-benzene, diethylene glycol, bis p-(beta-hydroxyethoxy) benzene, bis-4,4- (beta-hydroxyethoxy) diphenyl, 1,4-dihydroxy [2 2 2] bicyclooctane, 2,2-bis(4-hydroxyphenyl)-propane, 2,2-bis(4-hydroxycyclohexyl)propane, 1,4-cyclohexane-diol, 4,4'-dihydroxybiphenyl, and (bicyclohexyl)-4,4'-dimethanol. Other polyester-forming reagents include bifunctional compounds such as beta-hydroxypivalic acid, hydroxyacetic acid, and the like.

The following examples are cited to illustrate the invention. They are not intended to limit it in any way.

EXAMPLE I Eight parts of an isooctylphenylpolyethoxyethanol having an average of ether units per molecule (Triton X- 100, Rohm and Haas) is added to 8000 parts of ethylene glycol, stirred, and then mixed with 2000 parts of a commercially available kaolinite powder (ASP-170, Minerals and Chemicals Philipp Corp.) which has been purified by an ultraflotation process .(U.S. Pat. No. 2,990,958) to remove impurities and classified by centrifugation to provide an average equivalent spherical diameter of 0.55 micron with an (E.S.D.) g of 1.6 microns (by sedimentation measurements). The mixture, containing 0.4% by weight of defiocculant, based on weight of kaolinite, is ball milled for sixteen hours and then transferred to a holding tank where it is stirred for three days before using.

Kaolinite-m-odified polyethylene terephthalate is prepared, in an ester interchange-polymerization procedure, by introducing into a reaction vessel 1200 parts of dimethyl terephthalate, 800 parts of ethylene glycol, 0.56 part of manganous acetate tet'rahydrate, and 0.37 part of antimony trioxide. The mixture is heated at atmospheric pres sure and methanol removed by distillation until no additional methanol is evolved, the final temperature being about 240 C. The reaction mixture is then transferred to an autoclave, together with 0.8 part of phosphoric acid and a sufliicient quantity of the above-prepared glycol slurry of kaolinite to give the kaolinite concentrations shown in Table 1. The temperature of each mixture is raised to 275 C. and the pressure in the vessel reduced to 0.2 mm. of mercury while the mixture is agitated by a stirrer. Heating is continued and glycol vapor removed continuously as the polymer viscosity increases to the desired level, whereupon the polymer is extruded from the bottom of the autoclave as a ribbon, quenched in water and cut to flake. Even at the higher concentrations of kaolinite, the flake shows no delustering effect.

After drying, the flake is remelted in a screw extruder and supplied to a spinning position having a conventional sand pack-spinneret arrangement. The molten polymer is extruded through a 34-hole spinneret, quenched in air, and subsequently drawn 3.5X at C. by the process of Heighton (US. Pat. No. 3,101,990) to give a 70 denier (7.8 tex.) yarn having a break elongation of approximately 25%. Close examination of the drawn filaments reveals that the kaolinite particles are randomly dispersed throughout the polymer and oriented roughly parallel to the fiber axis. Each particle is surrounded by an elongated void which scatters light and reduces the transparency of the filament. The filament surface is characterized by numerous bumps and hollows.

The coefficient of friction of filaments taken from each yarn is measured according to the procedure described below with the results reported in the following table.

The coefiicient of hydrodynamic friction, f,., is measured by hanging a test filament over a /2-inch diameter polished, chrome-plated mandrel so that the filament contacts the mandrel over an arc of approximately 180. A 0.3- gram weight is attached to one end of the filament (input tension) and a strain gauge is attached to the other end (output tension). The mandrel is rotated at a speed of 1800 rpm. and the area of contact flooded with a drop of No. 50'mineral oil immediately before the strain gauge readings are made for data marked flooded. For data marked film, the oil is wiped from the mandrel with only a thin film remaining. The coefiicient, f,, is calculated from the belt equation: T /T =e where f is the coeflicient of hydrodynamic friction, T is the input tension, T is the output tension, and a is the angle of wrap.

Each batch of yarn prepared above is cut into 3 /z-inch staple and processed separately into spun yarn on the cotton system. The processability of the yarns containing the kaolinite particles is markedly better than that of the control yarns, showing reduced running tension, improved draftability, reduced roll wrapping, and the like.

EXAMPLE II The general procedure of Example I is repeated with the exception that 0.5% by weight, based on weight of kaolinite, of 3,6-dimethyl-4-octyne-3,6-dio1 is used in place of isooctylphenylpolyethoxyethanol. Substantially equivalent results are obtained.

EXAMPLE III The general procedure of Example I is repeated with the exception that 0.3% by weight (based on kaolinite) of sodium alkylnaphthalene sulfonate (Alkanol B, Du Pont) is used in place of isooctylphenylpolyethoxyethanol. Substantially equivalent results are'obtained.

EXAMPLE 1v For comparison purposes, an attempt was made to prerare suitable glycol dispersions of kaolinite using various :ommercially available surfactants. The following re agents vere not effective in producing a suitable deflocculated lurry:

)ioctyl ester of sodiumsulfosuccinate (Aerosol OT,

American Cyanamid Company),

Qauryldodecylpyridinium chloride,

& phosphate ester of the type where R is a water-solubilizing group and R is a medium-length alkyl group (Victawet 12, Victor Chemical Works),

[(2 hydroxyethyl) 2(pentadecyl) 2 imidazoline (Nalcamine 6-14, National Aluminate Corporation).

EXAMPLE V Following the general procedure of Example I, poly- :thylene terephthalate diake containing 1.5% kaolinite is prepared. Chemical analysis of the flake indicates a con- :entration of 15 mol percent ether linkages. The pro- :edure is then repeated with 0.05% sodium acetate triaydrate by weight, based on weight of dimethyl terephhalate, added to the polymerization mixture prior to tdding the kaolinite slurry. Flake produced from the lat- ;er procedure is found by analysis to contain less than 3 1101 percent ether linkages, which is considered suitable for all critical end uses.

EXAMPLE VI Following the general procedure of Example I, with the exception that no isooctylphenylpolyethoxyethanol is present, polyethylene terephthalate flake containing 1.5% kaolinite is prepared. The procedure is further modified by adding a suflicient quantity of 20% glycol slurry of H so that the final polymer contains 0.3% by weight H0 in addition to the kaolinite. The flake is then meltspun through a conventional sand pack-spinneret arrangement, fitted with a pressure gauge. The pressure build-up above the sand pack is found to be 276 p.s.i./hr.

The above procedure is repeated in all details with the exception that 0.4% isooctylphenylpolyethoxyethanol, based on kaolinite, is present in the kaolinite slurry added to the polymerization system, as in Example I. In this case, the pressure build-up above the sand pack is only 62 p.s.i./hour, or less than Mt that observed when no deflocculating agent is used, and equivalent tothat observed with conventional prior art polymers containing 0.3% by weight of TiO EXAMPLE VII A stream of monomeric bis-(Z-hydroxyethyDterephthalate prepared by the method of Vodonik (US. Pat. No. 2,829,153) and containing 0.02 weight percent antimony trioxide as a catalyst is fed to a continuous polymerization apparatus. Also supplied to the system is a 20% slurry of kaolinite prepared according to the general procedure of Example I, using 1.5 weight percent isooctylphenylpolyethoxyethanol as a deflocculating agent. Simultaneously, a 20% glycol slurry of Ti0 is injected into the system. The amounts of kaolinite and Ti0 slurries are adjusted to give the concentrations shown in Table 2. The temperature of the mixture is increased and the pressure reduced as it flows through a series of vessels with evolution of glycol, the final temperature being 275 C. and the final pressure being 1 millimeter of mercury in a vessel similar to that described by Pierce et al. in U.S. Pat. No. 3,057,702. The finished polymer is forwarded in a molten condition to a spinning machine, extruded through a 34-hole spinneret, quenched in a cross-flow air, and then drawn 3.5X at C. in the apparatus of Dusenbery (US. Pat. No. 3,045,315) to give a 70 denier (7.8 tex.) yarn having a nominal tenacity of 4 g.p.d. and a break elongation of 25%. Examination of the filaments shows a random dispersion of kaolinite particles, each associated with an elongated void Where the polymer has pulled away from the particle during the drawing operation. The filament surface is characterized by numerous bumps and hollows which produce a subdued surface luster. The coeflicient of friction is measured according to the procedure in Example I with the results shown in Table 2.

TABLE 2 Ooefiicient of friction (i Tenacity, Kaolinite, percent TiO Film Flooded g.p.d.

The marked reduction in friction achieved by the incorporation of kaolinite in polyester yarns is obvious on inspection of the tabulated comparative data.

EXAMPLE VIII A copolymer of polyethylene terephthalate containing 2 mol percent of S-sodiumsulfoisophthalic acid units in the polymer chain is prepared with 0.5, 1.0, 1.5 and 3.0 weight percent of kaolinite according to the general procedure of Example I, and melt spun to give a 70 denier (7.8 tex.) 34-filament yarn. Measurements of the coefiicients of friction of filaments taken from the yarns give the results shown in Table 3.

TABLE 3 Coefiicient of friction Kaolinite, percent: (f film 0.5 0.59

EXAMPLE IX Following the general procedure of Example I, several batches of polyethylene terephthalate flake are prepared containing about 2% kaolinite and about 0.3% TiO The reagents listed in Table 4 are used to disperse the kaolinite in glycol, the concentration in each case being 2% by Weight of dispersant, based on weight of kaolinite, With the exception of the control batch which has no dispersant. Each batch of flake is melt-spun and drawn into a 70-denier (7.8 tex.) yarn, with the rise in pack pressure being measured as in Example VI and recorded in Table 5. Tensile and friction measurements are made on the yarn with the results also shown in Table 5. Inspection of the pack pressure data in the table reveals unmistakably the improvement achieved by using carefully chosen dispersing agents in accord with'the present invention.

[Dispersant type: Fatty alcohol-ethylene oxide condensates having 9 to ethylene oxide units per molecule] Alcohol component Dispersant source Trade name Performance Stearyl alcohol Atlas Chemical Ind. Brij 76 Good.

Cetyl alcohol.-. .do B 56 Do.

Lauryl alcohol. do Brl Do.

Decyl alcohol Laboratory None Satisfactory.

preparation.

TABLE 7 [Dispersant type: Phenolic compound-ethylene oxide condensates having 9 to 30 ethylene oxide units per molecule] Ethylphenylphenol... Beacon Chemical Beaconol M.-- Good.

pany.

Com Diisopropylnaphtha- American Cyanamld Aerosol 08.... Do.

lene. Company. Dibutylnaphthalene General Dyestufi Leonil D0.

Corporation. Butylphenylphenol..- Monsanto Chemical Areskap 100..- Do.

Company.

EXAMPLE X TABLE 9 The general procedure of Example I is repeated using [Dispersant Ditetiary acetylemc glycols] various suitable dispersing agents in place of isooctyld S Performphenylpolyethoxyethanol, as shown in Tables 6-9. The 00mm Trade name ance dispersants are used at a concentration of 0.3% by weight, 5 lf-dimetlggl-S: 1 Aillteductign Suriynol102. Good. ecyne l0. 0111.108. 0

based on weight of kaolinite. Satisfactory results ar 2 4 7 g t t th smynol 104"" achieved as indicated in the tables. 5-decyne-4,7-d1ol.

' TABLE 4 t C d Di Sin 3 mt Trade name The present invention provides a practical and efiicient o e Sper g g 10 process for preparing useful polyester fibers containing IXa- None (control) IXb Isooctylphenylpolyetlioxyethanol Triton X-100. kaohmte partlcles The aqvaptages of reduced i (10mole percent ethylene oxide). faces luster and reduced friction, as well as the wide IXc Nonylphenoxyp y y Igepa100630- choice of luster effects obtained in combination with mole percent ethylene oxide). IXd Oleylalcoholethylenehoidde congepsate Alkanol HCS. 15 T102, y be achleved a Wlde Varlety of Polyester (20111011; percent et yene oxi e. yarns including for example the nonround cross-sec- 1 th 1 t dfatt lcohol Emul hor ON 870. Z h g1: 58.1 1857 glkzli iaiihthal egesulionate A] kan%1B tioned fibers disclosed by Holland in US. Pat. No.

(8.119415 Pwpylene tetramer 2,939,201 and US. Pat. No. 2,939,202, the cotton-blend- IXg Sodium dodecylbenzenesulionate Sorapon SF-78. 1x11 Dimethyloctynediol urfynol82. ing staple of Hebeler, US. Pat. No. 3,042,520, the high- IXi 214,7ygtetmmethylmecynwfldwlr Suriyn01465- bulk fibers of Killian, US. Pat. No. 3,050,821, the interethylene glycol condensate (65% by 20 weight ethylene glycol). laced continuous filament yarns of Bunting et al., US.

Pat. No. 2,985,995, the composite filaments of Jamie- TABLE 5 Yarn properties Coefficient of friction (fr) Pack pres- Kaollnite, TiO sure rise, Elong., Code percent percent p.s.i./hr. Ten., g.p.d. percent Film Flooded IXa 1.72 0.31 258 3.6 19 0.23 0.51 2. 19 0. 31 42 3.2 20 0. 24 0. 50 1.85 0. 31 40 3. 5 l8 0. 25 0. 57 1.80 0.27 3. 4 23 0. 32 0. e1 1. s0 0. 27 20 3. 2 22 0. 33 0. 69 1.83 0. 25 25 3. 6 26 0.30 0.69 1.91 0. 30 25 4. 0 21 0. 24 0. 68 1. 94 0. 25 25 3. 2 34 0. 2s 0. 64 1. as 0. 32 20 2. 5 1s 0. 26 0. 58

son, US. Pat. No. 2,980,492, the spontaneously extensible yarns of Kitson and Reese, US. Pat. No. 2,952,879, TABLE 5 and the bulky yarns of Breen, US. Pat. No. 2,783,609.

It is apparent that other variations and modifications of the disclosed procedures may be adopted without departing from the spirit of the present invention which is accordingly intended to be limited only by the scope of the appended claims.

EXAMPLE XI This example illustrates the strong effect of kaolinite on ether formation and the cancellation of that eflect by the presence of ether inhibitors.

A series of six polymers are prepared following the general ester interchange-polymerzation procedure of Example I. In each case a reaction vessel is charged with 12 lbs. (5.4 kg.) dimethyl terephthalate, 8 lbs. (3.6 kg.) ethylene glycol, and 120 m1. of a catalyst solution consisting of ethylene glycol containing 1.4 gms. antimony oxide and 2.10 gms. manganese acetate tetrahydrate per 100 ml. solution. The mixture is heated to complete ester interchange and then transferred to an autoclave where 24 ml. of a glycol solution of phosphoric acid containing 6.3% by weight phosphoric acid and ml. of a 20% by weight slurry of T10 in glycol is added. Polymerization is continued until the polymer obtains a melt viscosity equivalent to an intrinsic viscosity of approximately 0.58, whereupon the polymer is extruded, quenched, and cut to flake for analysis.

In the preparation of five of the six polymers the autoclave is also charged with 545 gms. of a glycol slurry of kaolinite prepared by mixing in a blender 436 gms. ethylene glycol, 0.2 gm. isooctylphenylpolyethoxyethanol, and 109 gms. of the kaolinite described in Example I.

Polymer A is prepared with no added kaolinite and no ether inhibitor.

In the preparation of Polymer B, sufiicient glycol slurry of kaolinite is added to the autoclave to provide 2% by 1 1 veight kaolinite on the weight of dimethyl terephthalate ised. No ether inhibitor is added.

Polymer C is prepared in the same manner as Polymer 3 with the exception that to the ester interchange relCtlOn is also added sufiicient sodium acetate to provide ).l% by weight sodium based on the weight of polymer roduced.

Polymer D is prepared in the same manner as Polymer 3 with the exception that sodium hydroxide is used as an :ther inhibitor instead of sodium acetate.

Polymer E is prepared in the same manner as Polymer 3 With the exception that potassium acetate is used as an :ther inhibitor in place of sodium acetate. Sufficient potas- ;ium acetate is used to provide 0.1% by Weight of potasiium based on weight of polymer produced.

Polymer F is prepared in the same manner as Polymer 3 with the exception that calcium acetate monohydrate is lsed in place of sodium acetate. Suflicient calcium acetate .s added to provide 0.1% by weight of calcium based on weight of polymer produced.

Each of the above polymers is analyzed for ether con- :ent, with the results shown in the following table:

The data in the table clearly show that kaolinite catalyzes the formation of ether linkages in the polymer, and that this catalytic effect is overcome by the addition of a small amount of ether inhibitor.

Ethers are determined in these samples by melt-pressing the polymer into a 3- or 7-mil (0.076- or 0.178-mm.) film at 285 15 C. and then measuring the absorption spectra using a commercial infrared spectrophotometer. Each spectrum is scanned from about 3.25 to about 3.45 microns and the ethers calculated from the ratio of absorbance due to ethers at about 3.25 microns to the absorbance due to film thickness at about 3.45 microns, both absorbances being corrected for the background absorbance found at about 3.28-3.29 microns. The ratio obtained is compared with the ratios given by films of known ether content to provide the values of mole percent ethers shown in the table.

Since many dilferent embodiments of the invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited by the specific illustrations except to the extent defined in the following claims. 1

What is claimed is:

1. In the process of preparing polyester fibers by ester interchange-polymerization of dimethyl terephthalate with ethylene glycol to form polyethylene terephthalate followed by melt-spinning of the polyethylene terephthalate through a filter pack and spinneret, and wherein from 0.25% up to 10% by weight of kaolinite is added before completion of said polymerization to provide polyester fibers having low surface friction; the improvement which comprises adding a base selected from the group consisting of hydroxides, acetates, formates, and carbonates of the alkali and alkaline earth metals to the polymerization mixture, prior to addition of the kaolinite, in the amount of 0.001 to 0.10% based on the weight of said dimethyl terephthalate used, and adding the kaolinite as a glycol slurry of kaolinite platelets with at least 0.2% by Weight of deflocculant based on the weight of kaolinite; said platelets being characterized as to particle size by equivalent spherical diameters in the range of 0.2 to 7 microns and (E.S.D.) values in the range of 1 to 5 microns, and said defiocculant being selected from the group consisting of condensation products of ethylene oxide and fatty alcohols containing 9-30 ethylene oxide units per molecule,

condensation products of ethylene oxide and substituted phenolic compounds containing 9-30 ethylene oxide units per molecule,

alkali metal salts of alkylarylsulfonic acids,

ditertiary acetylenic glycols of the formula wherein R and R are alkyl groups having 14 carbon atoms, and ethylene oxide condensates of said acetylenic glycols.

2. The process defined in claim 1 wherein, in addition to said kaolinite, a glycol slurry of titanium dioxide is also added before completion of the polymerization.

3. The process defined in claim 1 wherein sodium acetate is added to the polymerization mixture as said base.

No references cited.

MORRIS LIEBMAN, Primary Examiner S. M. PERSON, Assistant Examiner 7 Us, Cl.X.R. 260-332, 33.4, 40