AU623384B2 - Method of forming a nonwoven web from a surface-segregatable thermoplastic composition - Google Patents

Description

S F Ref: 90951 FORM COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE: l62338 Class Int Class Complete Specification Lodged: Accepted: Published: Priority: Related Art: 71~ Name and Address of Applicant: Address for Service: Kimberly-Clark Corporation Neenah Wisconsin 54956-0349 UNITED STATES OF AMERICA Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia Complete Specification for the invention entitled: Method of Forming a Nonwoven Web from a Surface-Segregatable Thermoplastic Composition The following statement is a best method of performing it full description of this invention, including the known to me/us 5845/3 Abstract of the Disclosure A nonwoven web is prepared by the method of forming a nonwoven web from a composition composed of at least one thermoplastic polymer and at least one defined siloxane-.

containing additive, which method involves the steps of forming fibers by extruding a molten thermoplastic composition through a die; drawing the fibers; (C) collecting the fibers on a moving foraminous surface as a web of entangled fibers; and either heating the web at a temperature of from about 27 to about 95° C for a period of time sufficient to cause additional additive to move to the surfaces of the fibers, or passing the web through o a pair of compacting rolls, at least one of which is o 15 heated, before removing the web from the foraminous surface.

J *The method of the present invention is particularly useful p o for the preparation of nonwoven webs, the fibers of which have at least one surface characteristic which is different from the surface characteristics of the polymer component of the thermoplastic composition. Such webs, in turn, are .0 0 useful in the construction of such disposable absorbent products as diapers, feminine care products, incontinence 4. products, and the like.

o4 4 0 o -1 METHOD OF FORMING A NONWOVEN WEB FROM A SURFACE-SEGREGATABLE THERMOPLASTIC COMPOSITIh6 Background of the Invention The present invention relates to a method of forming a nonwoven web from a surface-segregatable, melt-extrudable thermoplastic composition. More particularly, the present invention relates to a method of forming a nonwoven web from a thermoplastic composition which surface segregates in a controllable manner upon melt extrusion to form fibers having modified surface characteristics.

Polymers are used widely throughout the world to make S a variety of products which include blown and cast films, °o 15 extruded sheets, injection molded articles, foams, blow 04 S*0 molded articles, extruded pipe, monofilaments, and nonwoven webs. Some of such polymers, such as polyolefins, are naturally hydrophobic, and for many uses this property is S either a positive attribute or at least not a disadvantage.

Therd are a number of uses for polyolefins, however, where their hydrophobic nature either limits their usefulness or requires some effort to modify the surface charac- 4 4teristics of the shaped articles made therefrom. By way of example, polyolefins are used to manufacture nonwoven webs 25 which are employed in the construction of such disposable absorbent articles as diapers, feminine care products, incontinence products, and the like. Frequently, such ,ttI nonwoven webs need to be wettable. Wettability can be obtained by spraying or coating the web with a surfactant solution during or after its formation. The web then must be dried, and the surfactant which remains on the web is removed upon exposure of the web to aqueous media.

Alternatively, a surfactant can be included in the polymer which is to be melt-processed, as disclosed in U.S. Patent Nos. 3,973,068 and 4,070,218. In that case, however, the surfactant must be forced to the surface of the fibers from which the web is formed. This typically is done by heating the web on a series of steam-heated rolls or "hot cans". This process, called "blooming", is expensive and still has the disadvantage of ready removal of the surfactant by aqueous media. Moreover, the surfactant has a tendency to migrate back into the fiber which adversely affects shelf life, particularly at high storage temperatures. In addition, it is not possible to incorporate in the polymer levels of surfactant much above 1 percent by weight; surfactant levels at the surface appear to be limited to a maximum of about 0.33 percent by weight.

Most importantly, the blooming process results in web shrinkage in the cross-machine direction and a significant o. loss in web tensile strength.

I 15 Two common methods of preparing nonwoven webs are meltblowing and spunbonding. When using a surface-segre- Om a Sgatable, melt-extrudable thermoplastic composition to prepare a nonwoven web or fabric by either method as di-closed herein, it was found that certain problems could be encountered. Such problems typically were dependent upon the level of additive present in the composition 1 o prior to melt extrusion. For example, at additive levels o* o less than about 1 percent by weight, there often was insufficient additive present at the surfaces of the 6 25 fibers comprising the web to impart to the surfaces a characteristic of the additive. In addition, at levels of .additive of from about 1 to about 2 percent by weight, the o amount of additive at the fiber surfaces often was not as high as desired. The present invention addresses both problems.

Moreover, it was found in spunbonding processes that at additive levels equal to or greater than about 1 percent by weight, the formed web lacked coherency. That is, upon attempting to remove the web from the foraminous collecting surface, the web simply fell apart. The present invention addresses this problem and permits the use of spunbonding -2processes for the formation of nonwoven webs which have the necessary coherency for further processing and/or incorporation into products when the additive levels present in such thermoplastic composition are equal to or greater than about 1 percent by weight.

As is well known in the art, nonwoven webs may be formed by meltblowing in accordance with U.S. Patent Nos.

3,016,599, 3,704,198, 3,755,527, and 3,849,241; or by spunbonding in accordance with U.S. Patent Nos. 3,341,394, 3,655,862, 3,692,618, 3,705,068, 3,802,817, 3,853,651, 4,064,605, 4,340,563, and 4,434,204; or by coforming in accordance with U.S. Patent Nos. 4,100,324 and 4,118,531 to E. R. Hauser. See also U.S. Patent No. 4,663,220.

1 In addition to those already described, other methods 1 15 of imparting wettability to, or otherwise affecting the surface characteristics of, fibers or other shaped articles S. made from polyolefins and other hydrophobic polymers are known. Representative examples of a number of such methods Og° are described in the paragraphs which follow.

U.S. Patent No. 4,578,414 describes wettable olefin polymer fibers. The fibers are formed from a composition comprising a polyolefin resin and one or more defined surface-active agents. Such agents may be present in an amount of from about 0.01 to about 5 percent by weight.

25 The surface-active agents can be an alloxylated alkyl phenol in combination with a mixed mono-, di-, and/or triglyceride; or a polyoxyalkylene fatty acid ester; or a combination of with any part of The preferred polyolefin is polyethylene, and all of the examples employed an ethylene/l-octene copolymer, the latter apparently being a minor component. The surfaceactive agents are stated to bloom to the fabricated fiber surfaces where at least one of the surface-active agents remains partially embedded in the polymer matrix. The patent further states that the permanence of wettability -3can be controlled through the composition and concentration of the additive package.

Polysiloxane/polyoxazoline block copolymers are disclosed in U.S. Patent No. 4,659,777. The copolymers are stated to be useful as surface-modifying additives for base polymers. Such use apparently has primary reference to personal care products where the surface properties to be imparted include glossiness, smoothness, and lubricity.

However, incorporation of the copolymers into fibers is stated to impart surface stain resistance, antistatic properties, flame retardancy, and wettability by both polar and nonpolar solvents. Such incorporation preferably is in the range cof from about 1 to 5 parts by weight.

a a Suitable base polymers include some vinyl polymers, acrylate polymers, polyurethanes, cellulose derivatives, and polyethylene, polypropylene, ethylene-propylene copolymers, and copolymers of ethylene with, for example, vinyl acetate.

SHowever, the single example illustrating incorporation of the disclosed copolymers into a base polymer employed as the base polymer poly(vinyl chloride), and the resulting mixture was used to cast films from solution.

U.S. Patent No. 4,672,005 describes a process for 0" improvinq the hygroscopic, soil release, and other surface properties of a polymer substrate. The process involves contacting the substrate with an aqueous mixture containing a water-soluble vinyl tonomer and a hydrophobic vinyl .monomer. Polymerization of the water-soluble vinyl monomer then is initiated by a polymerization initiator, thereby forming a vinyl polymer on the surface of the polymer substrate.

U.S. Patent No. 4,698,388 describes a method for modifying the surface of a polymer material by means of a block copolymer. The block copolymer consists of a hydrophilic polymer portion formed from a vinyl monomer and a polymer portion which is compatible with the polymer material, also formed from a vinyl monomer. The block I Fi 1 copolymer is added to the polymer material by, for example, coating the material with a solution or suspension of the block copolymer, mixing the block copolymer with the polymer material during formation of the article, forming a film from the block copolymer which then is melt-pressed or adhered to the surface of the polymer material, and coating the surface of the polymer material with powdered block copolymer.

Polymer compositions having a low coefficient of friction are described by U.S. Patent No. Re. 32,514.

The compositions comprise a blend of at least 80 percent by weight of a polymer and at least 0.35 percent by weight of a crosslinked silicone polycarbinol. The polymer preferably is a blend of cellulose nitrate and a hydrophobic acrylate polymer. The silicone polycarbinol in general is o a hydroxy-terminated polysiloxane or hydroxy-substituted polysiloxane. The compositions typically are prepared by od dissolving the polymer or polymer blend, silicone polycarbinol, and crosslinking agent in a suitable solvent and casting a film from which the solvent is allowed to evaporate.

Canadian Patent No. 1,049,682 describes the inclusion S.in a thermoplastic polymer of from 0.1 to 10 percent by weight of a carboxy-functional polysiloxane. Suitable thermoplastic polymers include polyolefins. Such inclusion is stated to enhance the properties or characteristics of the thermoplastic polymer in one or more ways. By way of I illustration, products or articles made from the polymer mixture were stated to have self-lubricating properties and increased resistance to wear. For molded articles, less friction during transfer, injection or extrusion molding was observed, and better release of parts from the molds was obtained. See, also, German Published Patent Application (Offenlegutgschrift) No. 2,506,667 Chem. Abstr., 84:91066z (1976)].

Other, similar references which may be of interest include R. H. Somani and M. T. Shaw, Macromolecules, 14, 886 (1981), which describes the miscibility of polydimethylsiloxane in polystyrene; and S. N. Pandit et al., Polym.

Compos., 2, 68 (1981), which reports the use of a vinyltriethoxysilane polymer as a coupling agent in glass fiberreinforced polypropylene.

Also for the sake of completeness, it may be noted that polysiloxanes have been utilized in the production of nonwoven webs or fabrics, or products made therefrom, as illustrated by the references which follow.

U.S. Patent No. 3,360,421 describes a bonded nonwoven backing material having perforate selvage which is used in the manufacture of carpet. In the production of the Sj 15 nonwoven backing material, a nonwoven web is produced from a polyolefin such as polyethylene or polypropylene. The Sresulting web then is subjected to bonding conditions, followed by applying to the web a lubricant which can be, So among other things, methyl hydrogen polysiloxane and dimethyl polysiloxane.

A finish composition for application to a continuous filament polypropylene sheet is disclosed in U.S. Patent No. 3,766,115. The composition comprises a mixture of two polysiloxane components, the first of which is a dyeable component comprising a primary or secondary aminoalkyl- or Saminoalkoxyalkylpolysiloxane fluid having an amine functionality in the range of 4-7 percent and being substantially free of other reactive groups. The second component is a lubricant component comprising a polydialkyl/arylsiloxane S 30 fluid having hydroxy end groups and being substantially free of other reactive groups. The polypropylene sheet typically is a spunbonded sheet made from isotactic polypropylene.

U.S. Patent No. 3,867,188 relates to a spunbonded nonwovcn fabric which is especially useful as a carpet -6backing. The fabric has on it a silicone-glycol copolymer having the general formula:

(CH

3 3 SiO((CH 3 2 SiO)x((CH 3 )GySSi(CH 3 3 in which G is a radical of the structure -R(C 3

H

6 )zOH, R is an alkylene radical containing from 1 to 18 carbon atoms, x has an average value of from 40-90, y has an average value of from 1-10, and z has an average value of from 1-10.

U.S. Patent No. 3,929,509 describes a hydrophilic microporous film which is useful as a battery separator.

The film comprises a hydrophobic microporous film coated with a silicone glycol copolymer surfactant, preferably at a level of from 2 to 20 percent by weight, based on the S 15 uncoated film. In preferred embodiments, the surfactant coating comprises a mixture of a silicone glycol copolymer o: surfactant and a second surfactant which preferably is an imidazoline tertiary amine. The silicone glycol copolymer SOO surfactant preferably is a polyoxyethylene polymethylsiloxane.

A yarn finish formulation is disclosed in U.S. Patent "a No. 4,105,569. In preferred embodiments, the formulation oO contains a hydrocarbon-soluble, long molecular chain polymeric viscosity improver, such as polyisobutylene, and I o° 25 a polysiloxane. Preferably, the polysiloxane is an alkoxylated polysiloxane, such as a dimethylpolysiloxane with substituted polyethylene glycol or polypropylene glycol 'o side chains or mixed polyethylene/polypropylene glycol side chains.

U.S. Patent No. 4,563,190 describes a siloxane/oxyalkylene copolymer as an optional component of a dyeing assistant for dyeing or printing polyamide fiber material with anionic dyes. See also U.S. Patent Nos. 4,444,563 and 4,426,203.

U.S. Patent No. 4,645,691 describes a method for treating materials with organopolysiloxane compounds. The -7method involves applying to the material a composition containing a silicone compound which has one or more alkoxysilylalkyl groups and one or more polyoxyalkylene groups. The materials to be treated preferably are fibers and fiber-containing materials.

For a limited review of similar applications of silicones, see A. J. Sabia and R. B. Metzler, Nonwovens Ind, 14, 16 (1983). Also note British Patent No. ,,273,445 [Chen. Abstr., 76: 89559z (1972)], which describes the use of a block polysiloxane, among other materials, in the preparation of a leather substitute.

It may be noted that the above review briefly discusses polysiloxanes which have been modified by inclusion of a poly(oxyalkylene) moiety; such modified polysiloxanes can S" 15 be employed in the composition of the present invention as sot an additive.

O°o q A modified polysiloxane in which the poly(oxyalkylene) moiety is a poly(oxypropylene) is described in U.S. Patent 6 No. 3,867,188. The modified polysiloxane apparently is 20 employed as a lubricant which coats a spunbonded nonwoven fabric. The fabric, in turn, is employed as a carpet bao backing. The addition of the modified polysiloxane to the backing is stated to reduce damage to the backing whioh 0 t results from the tufting process used to manufacture the .0 25 carpet.

Additionally, polysiloxanes have been used in the manufacture of films. For example, U.S. Patent No.

4,652,489 describes a sealable, opaque polyolefinic multilayer film. The film is composed of a polypropylene base layer a nonsealable surface layer, and a sealable surface layer. The nonsealable layer is a combination of a propylene homopolymer and a slip agent which preferably is a polydiorganosiloxane. The polydiorganosiloxane is used in an amount of from about 0.3 to about 2.5 percent by weight and preferably comprises a polymethylphenylsiloxane or a polydimethylsiloxane.

Finally, several references are known which are or may be of interest in relation to the 1. tditive when it contains a disubstituted siloxane. Such references are described below.

Siloxane-oxyalkylene block copolymers are disclosed in U.S. Patent No. 3,629,308. The copolymers are stated to be particularly useful as a foam stabilizer in the production of polyurethane resin foams. The copolymers are represented by the formula: RO R II

I

R

3 SiO(RSiO)r[R' (OCmH2m)nOR -Si-O-]pSiR3 in which R is a monovalent hydrocarbon group, Eo is hydrogen o or a monovalent hydrocarbon group, R' is hydrogen or a monovalent hydrocarbon group, R is a divalent hydrocarbon group, r has a value of at least 0, m is an integer that has a value of at least 2, n is a number that has a value a 20 of at least 1 (preferably at least p is a number that has a value of at least 1, there are not more than three O hydrogen atoms represented by R 0 in the copolymer (preferably less than one or none), and at least 25 weight-percent of the groups represented by (OCmH2m) are oxyothylene groups.

U.S. Patent No. 4,150,013 describes melt-procesible .tetrafluoroethylene copolymers containing organopolysiloxanes which are useful as wire insulation coatings. The "2 organopolysiloxane is present in an amount of between about 0.2 and 5 percent by weight, based on the weight of the resulting copolymer composition. Representative organopolysiloxanes include polyphenylmethylsiloxane, polydimethylsiloxane, polymethylsiloxane, a copolymer of phenylmethylsiloxane and dimethylsiloxane, and the like.

A high viscosity silicone blending process is disclosed in U.S. Patent No. 4,446,090. The blends produced by the -9process are stated to have engineering properties and flame retardance superior to known blends. The process involves melting a solid thermoplastic composition comprising one or more thermoplastic polymers within an extruder, injecting a high viscosity silicone fluid into the molten thermoplastic composition within the extruder, and blending said molten thermoplastic composition with said high viscosity silicone fluid within the extruder. The thermoplastic compositions include polyethylene and polypropylene. The silicone fluid typically is a polydimethylsiloxane. The blend can contain such additives as reinforcing fillers, antioxidants, lubricants, flame retardants, and the like. The additives can be introduced by means of the thermoplastic polymers, the silicone fluid, or both. Typical flame retardants include magnesium stearate, calcium stearate, barium ;stearate, antimony oxide, and decabromodiphenyloxide.

Siloxane-containing polymers are described in U. ,S Patent Nos. 4,480,009 and 4,499,149. The properties of 9 20 polymeric compositions are stated to be improved by the presence of a polysiloxane unit having a defined formula.

The listing of polymers, however, does not include polyolefins. The disclosed compositions apparently are useful as protective coatings and as molding, extruding, laminating, S 25 and calendaring comporitions. Solutions of the compositions ,-an be used to prepare films and fibers.

U.S. Patent No. 4,500,659 relates to extrudable, curable polyorganosiloxane compositions. The compositions are similar to those of U.S. Patent No. 4,585,830, described below. In the present case, the compositions comprise (A) a liquid triorganosiloxy end-blocked polydimethylsiloxane wherein the triorganosiloxy units are dimethylvinylsiloxy or methylphenylvinylsiloxy; a reinforcing silica filler which has been reacted with a liquid or solubilized treating agent, at least one component of which is a liquid hydroxy end-blocked polyorganosiloxane wherein at II l least 50 percent of the silicon atoms are bonded to a fluorine-substituted hydrocarbon radical; a liquid methylhydrogensiloxane having an average of at least three silicon-bonded hydrogen atoms per molecule; and a platinum-containing catalyst. The bonded treating agent for the silica filler would be incompatible, insoluble, with the polydimethylsiloxane component it were not bonded to the silica.

Olefin polymer compositions containing silicone additives are described in U.S. Patent No. 4,535,113.

The compositions apparently can be extruded through relatively narrow die gaps at commercial extrusion rates to provide films having improved optical and mechanical properties. The silicone additives have the formula, o o° (R)Si-O-[Si(R) (R l Ao in which each R, which can be the same or different, is an alkyl radical preferably having from one to six carbon atoms, R 1 is a monovalent organic radical containing at least one ethyleneoxide group, vicinal epoxy group, or amino group, and x and y, which can be the same or differ- 1, ent, each have a value of at least 1 and generally have a S" value of from about 4 to about 5,000. The silicone addi- 25 tives typically are present in the compositions in an amount of from about 0.01 to about 5 percent by weight.

U.S. Patent No. 4,585,830 describes polyorganosiloxane compositions useful for preparing unsupported extruded profiles. Such compositions are stated to include a triorganosiloxy end-blocked polydiorganosiloxane containing at least two vinyl radicals per molecule, in which at least 50 percent of the silicon-bonded organic radicals are methyl; and an organohydrogensiloxane containing at least two silicon-bonded hydrogen atoms per molecule, in which said hydrogen atoms are bonded to different silicon atoms. Examples of such two types of compounds are di- -11iL, 4 40 44 o 4 04 e4 44 4, 4 A. 4* o i, A 049 4 It 44 methylvinylsiloxy end-blocked polydimethylsiloxanes and trimethylsiloxy end-blocked dimethylsiloxane/methylhydrogensiloxane copolymers, respectively.

From the foregoing, it is evident that surfactants have been added to polymers to impart a hydrophilic character to the surface of the shaped article made from the polymer. These efforts appear to fall into either of two categories. In the first category, the surfactant is compatible with the polymer at melt-extrusion temperatures, in which the shaped article must be bloomed or heated after formation thereof to bring the surfactant to the surface.

However, the surfactant is incompatible at melt-extrusion temperatures. In the second, the surfactant moves spontaneously to the surface of the shaped article because it 15 is incompatible with the polymer at any temperature. Such incompatibility at melt-extrusion temperatures prevents the use of such surfactants in the formation of meltextruded fibers because the surfactant prevents the continuous formation of fibers.

20 Although surface-segregatable, melt-extrudable thermoplastic compositions are a significant advance in the art of modifying the surface characteristics of fibers prepared from a thermoplastic polymer, there is a need to overcome the aforementioned problems associated with the use of such compositions in the formation of nonwoven webs by such processes as meltblowing, spunbonding, and coforming.

Summary of .it Invention j 4* 30 Accordingly, the present invention provides a method of forming a nonwoven web from a surface-segregatable, melt-extrudable thermoplastic composition which comprises at least one thermoplastic polymer and at least one siloxane-containing additive having at least two moieties, A and B, which method comprises the steps of: -12- 5845/3 forming fibers by extruding a molten thermoplastic composition through a die; drawing said fibers; collecting said fibers on a moving foraminous surface as a web of entangled fibers, which fibers have less than about 0.35 percent by weight, based on the weight of said fibers, of solvent-extractable additive at their interfacial surfaces and have surface properties characteristic of said at least one thermoplastic polymer; and heating said web at a temperature of from about 27 to about 95" C for a period of time sufficient to provide at least about 0.35 percent by weight, based on the weight of said fibers, of solventas extractable additive at the interfacial surfaces of the fibers, which fibers have a surface o property characteristic of said at least one additive as a consequence of said heating; in which: said additive is compatible with said polymer at Smelt extrusion temperatures but is incompatible at tempera- K tures below melt extrusion tempeCatures, but each of said moiety A and moiety B, if present as separate compounds, (25 would be incompatible with said polymer at melt extrusion temperatures and at temperatures below melt extrusion temperatures; moiety B has at least one functional group which imparts to said additive said at least one characteristic; the molecular weight of said additive is in the range of from about 400 to about 10,000; and said additive is present in said thermoplastic composition at a level of from about 0.5 to about 2 percent by weight, based on the weight of said polymer.

The present invention further provides a method of forming a nonwoven web from a surface-segregatable, melt- -13-

I

extrudable thermoplastic composition which comprises at least one thermoplastic polymer and at least one siloxanecontaining additive having at least two moieties, A and B, which method comprises the steps of: forming fibers by extruding a molten thermoplastic composition through a die; drawing said fibers; collecting said fibers on a moving foraminous surface as a web of entangled fibers, which fibers have at least about 0.35 percent by weight, based on the weight of said fibers, of solvent-extractable additive at their interfacial surfaces and have a surface property characteristic of said at least one additive; and O/ 15 heating said web at a temperature of from about 0 0 27 to about 95" C for a period of time sufficient ao 0 to increase the amount of solvent-extractable 0 Ik to additive at the interfacial surfaces of the Ca 0 94 fiber to at least about 0.75 percent by weight, 20 based on the weight of said fibers; in which: said additive is compatible with said polymer at melt extrusion temperatures but is incompatible at tempera- 7! tures below melt extrusion temperatures, but each of said 4C 25 moiety A and moiety B, if present as separate compounds, would be incompatible with said polymer at melt extrusion .temperatures and at temperatures below melt extrusion temperatures; i moiety B has at least one functional group which Sr 30 imparts to said additive said at least one characteristic; the molecular weight of said additive is in the range of from about 400 to about 10,000; and said additive is present in said thermoplastic composition at a level of from, about 0.5 to about 2 percent by weight, based on the weight of said polymer. -14- The present invention also provides a method of forming a nonwovan web comprising the steps of: forming continuous filaments by extruding a molten thermoplastic composition through a die; quenching said continuous filaments to a solid state; drawing said filaments; collecting said continuous filaments on a moving foraminous surface as a web of entangled filaments; and passing said web between a pair of compacting rolls, at least one of which is heated, before removing said web from said movurig foraminous surface, said compacting rolls applying heat and pressure to said web aufficient to impart coherency thereto; wherein said thermoplastic composition comprises a surfacesegregatable, melt-extrudable thermoplastic composition which comprises at least one thermoplastic polymer and at o. 20 least one additive having at least two moieties, A and B, in which: S• said additive is compatible with said polymer at melt extrusion temperatures but is incompatible at temper- Satures below melt extrusion temperatures, but each of moiety A and moiety B, if present as separate compounds, would be incompatible with said polymer at melt extrusion temperatures and at temperatures below melt extrusion 4 temperatures; S4 moiety B has at least one functional group which imparts to said additive at last one desired characteristic; said additive is a siloxane-containing compound; 1444 the molecular weight of said additive is in the range of from about 400 to about 10,000; and the weight ratio of said polymer to said additive is in the range of from about 10 to about 100.

L

In preferred embodiments, moiety A comprises at least one tetrasubstituted disiloxanylene group, optionally associated with one or more groups selected from the group consisting of trisubstituted silyl and trisubstituted siloxy groups, the substituents of all such groups being independently selected from the group consisting of monovalent alkyl, cycloalkyl, aryl, and heterocyclic groups, each of which is substituted or unsubstituted, and moiety

B.

In still other preferred embodiments, the additive contains a plurality of groups selected from the group consisting of the following general formulae:

B

1

B

2

R

1

R

2 -Si=,

(R

3

)(R

4

(R

5 )Si-,

(R

6

)(R

7

(R

8 )Si-O-, o\ [-Si(R 9 and 20 [-Si(R 1 (B3)-O-jb; in which each of R and R 2 independently is a monovalent group selected from the group consisting of hydrogen, alkyl, cycloalkyl, aryl, and heterocyclic groups, each of which, except for hydrogen, is substituted or unsubstituted; each of R 3

-R

5 inclusive, independently is a monovalent group selected from the group consisting of alkyl, *cycloalkyl, aryl, and heterocyclic groups, each of which is substituted or unsubstituted, and B 4 each of R 6 -Ril, inclusive, independently is a monovalent group selected from the group consisting of alkyl, cycloalkyl, aryl, and heterocyclic groups, each of which is substituted or unsubstituted; each of a and b independently represents an integer from 0 to about 70 which indicates only the quantity of the respective group present in the additive without indicating or requiring, in instances when an integer is greater than 1, that such plurality of the respective -16- -3- I _I i group are connected to one another to form an oligomer or polymer or that all of such groups have identical substituents; and each of B 1

-B

4 inclusive, independently is a moiety which imparts to the additive at least one desired characteristic; with the proviso that such plurality of groups results in at least one tetrasubstituted disiloxanylene group.

In still other preferred embodiments, the additive is a compound having the general formula, R12

B

5 -0-(-Si-O-)c-B6

R

13 in which each of R 12 and R 13 independently is a monovalent group selected from the group consisting of hydrogen, alkyl, cycloalkyl, aryl, and heterocyclic groups, each of which, except for hydrogen, is substituted or unsubsti- 20 tuted; each of 8 5 ai\d B 6 independently is a monovalent group having a desiredl characteristic; and c represents an o integer from 2 to about In yet other preferred embodiments, the additive is a compound having the general formula, R17 R 19

R

20 o R 1 4 d- (-Si--)e-Si-R1 S.0 I I I I S°

R

16 R18 B7 R22 in which each of R 14

-R

22 inclusive, independently is a monovalent group selected from the group consisting o\f hydrogen, alkyl, cycloalkyll aryl; and heterocyclic groups, ^i each of which, except for hydrogen, is substituted or 1 unsubstituted; B 7 is a monovalet group having a desired characteristic; d represents an integer from 0 to about and e represents an integer from 1 to about -17- 3; ij j JL material, also formed from a vinyl monomer. The block -4- In yet other preferred embodiments, the additive is a compound having the general formula, R24 1 R'A3-Si[ f-B 8 1] 3 in which each of R 23

-R

25 inclusive, independently is a monovalent group selected from the group consisting of hydrogen, alkyl, cycloalkyl, aryl, and heterocyclic groups, each of which, except for hydrogen, is substituted or unsubstituted; B 8 is a monovalent group having a desired characteristic; and f represents an integer from 1 to about The process of the present invention is particularly useful for the preparation of nonwoven webs, the fibers of which have at least one surface characteristic which is different from the surface characteristics of 'the polymer component of the thermoplastic composition. Such webs, in turn, are useful in the construction of such disposable i Qabsorbent products as diapers, feminine care products, incontinence products, and the like.

Brief Description of the Drawings Figure IA is a generaliz.d flow diagram illustrating 4 one process of the present invention.

Figure 1B is a generalized flow diagram illustrating 0 another proces of the present invention.

Figure 2 consists of two hand-drawn representations of photomicrographs of a composition of the present invention, S ie., the fibers of Example 325, taken through a hot-stage microscope at two different temperatures and a magnification of 350X.

Figure 3 consists of two hand-drawn representations of photomicrographs of the polymer component only of the fibers JJ AJ=;rv u .J.AflQ S-, of Example 325, taken through a hot-stage microscope at two different temperatures and a magnification of 350X.

Figure 4 consists of two hand-drawn representations of photomicrographs of the composition of Example 38 consisting of the polymer component of the fibers of Example 325 and an incompatible silicon-containing compound, taken through a hot-stage microscope at two different temperatures and a magnification of 350X.

Figure 5 consists of two hand-drawn representations of photomicrographs of the composition of Example 43, taken through a hot-stage microscope at two different temperatures and a magnification of 350X.

Figure 6 is a diagrammatic representation of a section of melt-pressed film prepared from a composition of the present invention, as described in Examples 129-173, inclusive.

Figure 7 is a diagrammatic representation of a scanning electron micrograph, using a silicon x-ray probe, of a sample of the film of Example 169, superimposed on the S*o 20 diagrammatic representation of Figure 6, which film was prepared from a composition of the present invention in m which tha additive was a silicon-containing compound.

SFigure 8 is a plot of silicon concentration in atom A percent versus depth in A below the interfacial surface for a sample of the film of Example 169, the data for the plot having been obtained by Rutherford back scattering .spectrometry.

i Figure 9 is a diagrammatic representation of a scanning electron micrograph, using a silicon x-ray probe, of a section of the spunbonded ronwoven web of Example 361 prepared from a composition of the present invention, in which the additive was a silicon-containing compound.

Figures 10 and 11 are plots of silicon concentrations in atom percent versus depth in A below the interfacial surface for the fibers of two spunbonded nonwoven webs made in accordance with the present invention, in which -19i--I 1 i a.J wnu.n fspe.C±a±y useru. as a carpet -6i' the additive was a silicon-containing compound, the data for the plots having been obtained by Rutherford back scattering spectrometry.

Figure 12 consists of two hand-drawn representations of photomicrographs of a composition consisting of the polymer component of the fibers of Example 325 and a surfactant commonly used in a blooming process to render polypropylene fibers wettable, taken through a hot-stage microscope at two different temperatures and a magnification of 350X.

Detailed Description of the Invention One method of the present invention applies to any nonwoven process, to meltblowing, spunbonding, and coforming processes. The other method of the present invention applies only to a spunbonding process. For convenience, the two methods will be discussed separately as the general method and the spunbonding method, respectively.

*o 20 The nature of the thermoplastic composition employed in both methods then will be described.

The General Method I In the first step of the general method of the present 4I** invention, fibers are formed by extruding a molten thermo plastic composition, hereinafter defined, through a die.

Although the nature of the die is not known to be critical, S .it most often will have a plurality of orifices arranged 0 4 in one or more rows extending the full machine width.

Such orifices may be circular or noncircular in cross- 30 section. The fibers extruded may be either continuous or discontinuous.

Sti The fibers then are drawn, typically by entraining them in a fluid stream having a sufficiently high velocity.

When continuous fibers are produced, the fibers first are cooled in a quenching fluid which usually is low pressure air. The fluid stream which draws the fibers, usually air, k 1 T _ii can be a stream of high velocity air separate from the quenching fluid, or it can be a portion of the quenching fluid which is accelerated by passage into a narrow nozzle.

In the production of discontinuous fibers, on the other hand, the fluid stream isuvally is a heated, high velocity stream of air which draws the fibers while they are in an at least partially molten or softened state.

The drawn fibers then are collected on a moving foraminous surface as a web of entangled fibers. The foraminous surface can be, by way of example only, a revolving drum or a continuous belt or wire screen; the latter is most commonly used on commercial-scale equipment.

In some cases, the collected fibers will have at their interfacial surfaces less than about 0.35 percent by weight, based on the weight of the fibers, of solventextractable additive. Such fibers typically will have surface properties characteristic of the at least one thermoplastic polymer component of the thermoplastic o*o composition from which the fibers were prepared. When the 20 co2.lected fibers have at their interfacial surfaces at least about 0.35 percent by weight, based on the weight of the a fibers, of solvent-extractable additive, the fibers typically will have surface properties characteristic of the additive.

As used herein, the term "solvent-extractable additive" refers to additive which is on or sufficiently close to .the interfacial surfaces of the fibers to be removed by a mild extraction procedure that does not result in fiber swelling. An example of such a procedure is soaking or agitating the fibers in isopropanol for 5-15 minutes. The amount of additive present in the extract then is readily determined by known means, such as by either gravimetric Or chromatographic analysis.

Finally, the Web of entangled fibers is heated at a temperature of from about 27 to about 95' C for a period of time sufficient to cause additional additive to move to -21the surfaces of the fibers. As a general rule, heating times of from about 1 to about 30 seconds will accomplish the desired movement of additive to the surfaces of the fibers. However, longer or shorter times can be used, depending upon the level of additive in the thermoplastic composition, the average molecular weight and molecular weight range (polydispersity) of the' additive', and the desired additive level at the fiber sirfaces. Preferably, heating times of from about 1 to about 5 seconds at a temperature of from about 65 to about 85° C will be employed.

When the web before the heating step has surface properties characteristic of the at least one thermoplastic polymer component of the composition from which the fibers were made, the fiber surfaces typically have at their interfacial surfaces an amount of solvent-extractable additive which is less than about 0.35 percent by weight, based on the weight of fibers. In this context, the os heating step will cause the amount of solvent-extractable 20 additive at such surfaces to increase to at least about o °o 0 0.35 percent by weight, which in turn results in the fibers having a surface property characteristic of the at I 4 least one additive present in the melt-extruded composition.

Preferably, the heating step will increase the amount of surface-extractable additive at the fiber surfaces to at least about 0.75 percent by weight, and most preferably to '.at least about 1 percent by weight, based on the Weight of the fibers.

On the other hand, when the fibers of the web have, before the heating step, a surface property characteristic of the at least one additive present in the composition, the amount of solvent-extractable additive at the surfaces of the fibers usually is greater than about 0.35 percent by weight, based on tho weight of fibers. However, such amount usually is less than about 0.75 percent by weight.

Consequently, the heating step is intended to increase the -22amount of solvent-extractable additive at the fiber surfaces to at least about 0.75 percent by weight and preferably to at least about 1 percent by weight, based on the weight of the fibers.

The heating step can be accomplished by any known means. For example, the web can be irradiated with infrared or microwave radiation, passed through an oven, or passed over one or more heated rolls. If heated rolls are used, such rolls in turn may be heated by any convenient means.

Thus, such rolls can be heated with steam or by a circulating heated oil or other heat-exchange medium. Alternatively, the surfaces of the rolls can be irradiated with, e.g., infrared radiation, In general, heated rolls alce preferred for continuous processes. However, it is not necessary that the heating step immediately follow the formation of the web. That is, the web may be formed as described, then wound up as a roll of fabric and stored or set aside temporarily. The stored roll of fabric then can be unwound Sand subjected to the heating step.

0. V 20 Some aspects of the method of the present invention o are described in more detail in earlier-referenced U.S.

Q Patent Nos. 3,016,599, 3,704,198, 3,755,527, 3,849,241, 1' 3,341,394, 3,655,862, 3,692,618, 3,705,068, 3,802,817, 3,853,651, 4,064,605, 4,340,563, 4,434,204, 4,100,324, 4,118,531, and 4,663,220, all of which are incorporated herein by reference.

The general method is further described by reference S* to Figure IA which is a generalized flow diagram illustrating a preferred embodiment. Although Figure IA illustrates a typical spunbonding process, it should be understood by those having ordinary skill in the art that meltblowing or other methods may be used.

In discussing Figure IA, the term "filamentss is used to emphasize the continuous nature of the fibers produced JS by the spunbonding process. For the purposes of the present invention, however, the terms "filaments" and "fibers" are -23used synonymously. Thus, the use of either term should not be construed as in any way limiting the scope of the present invention.

Turning now to Figure 1A, the thermoplastic composition is fed from supply 10 to hopper 12, then through extruder 14, filter 16, and metering pump 17 to die head 18 having die face 22 with a plurality of orifices arranged in one or more rows generally in the cross-machine direction. As the continuous fila..ents emerge from die face 22, they form a curtain of filaments 20 directed into quench chamber 2A. In the quench chamber 24, filaments are contacted with air or other cooling fluid through inlet 26. The quenching fluid is maintained at a temperature which is lower than the temperature of the filaments 20, typically at ambient temperature, in the range of from about 4 to about 55° C. The quenching fluid is supplied under low pressure, less than about 12 psi, and preferably is than about 2 psi, and a portion prefer- 0. 0 ably is directed through the curtain of filaments 20 and removed as exhaust through port 28. The proportion of a' 0 quenching fluid supplied that is discharged as exhaust Swill depend upon the composition being used and the rapidity Sof quenching needed to give the desired filament characteristics, such as denier, tenacity, and the like. In general, the greater the amount of fluid exhausted, the i«a larger the resulting filament denier and, conversely, the S° ".lower the exhaust fluid ratio, the lower the filament SO" deniar.

oa As quenching is completed, the curtain of filaments 20 is directed through a smoothly narrowing lower end of the quenching chamber into nozzle 32 where the quenching o fluid attains a velocity of from about 45 to about 245 meters per second. Nozzle 32 extends the full width of the mach..e, equivalent to the width of die 22. Nozzle 32 preferably is formed by a stationary Wall 34 and a movable wall 36, both of which also span the width of the machine.

-24- The function of movable wall 36 is described in said U.S.

Patent No. 4,340,563.

After exiting nozzle 32, filamuents 20 are collected on a moving foraminous surface such as an endless screen or belt 38 to form a nonwoven web 40. Before being removsd from belt or screen 38, web 40 is passed under compaction roll 42, optionally in conjunction with guide roll 46.

Compaction roll 42 conveniently is opposed by the forward drive and/or support roll 44 for the continuous foraminous belt or wire screen 38. Compaction roll 42 typically is not heated, although it could be, if desired. Upon exiting compaction rct 1 42, the web is bonded at roll nip 48. Ths web then is passed over two steam-heated rolls' 52. and 52 having a surface tzemperature of about 85' C, after which the web is wound on take-up roll 54. Combined or total residence times of the web on rolls 51 and 52 typically is in the range of from about I to about 5 seconds, although 00 longer or shorter times can be used, depending upon the nature of the additive, the extent to which additive already is located at the surfaces of the fiberai, and the desired final amount of additive at the fiber surfaces.

Polls 51 and 52, as already noted, may be heated by any convenient means (not shown). For example, a heated fluid may be circulated through them as described in the Examples.

Alternatively, the surface of rolls may be irradiated by infrared heatkrs or lamps with appropriate surface temper- ,.ature monitors in order to control the surface temperatures of the rolls.

The Sp2unbondinT Method presenthf itstpco tinuospufilagmetaehord yh irtn stouhespunondgmethaeord ofyh extruding a molten thermoplastic composition, hereinafter defined, through a die. Although the naturt, of the die is not known to be critical, it most often iwill have a plurality of orifices arranged in one or moret, ri:ws extending the

II-

44 4 04a 4 4P 0 4 44 41 4 II r 4 4 full machine width. Such orifices may be circular or noncircular in cross-section.

The continuous filaments thus formed then are quenched by means of a quenching fluid, usually air, which is at a temperature lower than that of the filaments as they emerge from the die. The purpose of the quenching fluid is to cool the filaments to a solidified state. Most often, low pressure air is used.

The solidified filaments are drawn or attenuated, typically by entraining the filaments in a fluid stream having a sufficiently high velocity. The fluid stream, which usually also is air, can be a stream of high velocity air separate from the quenching fluid or a portion of the quenching fluid which is accelerated by passage into a narrow nozzle.

The drawn continuous filaments then are collected on a moving foraminous surface as a web of entangled filaments.

The foraminous surface can be, by way of example only, a revolving drum or a continuous belt or wire screen; the latter is most comronly used on commercial-scale equipment.

Finally, the web of entangled fibers is passed between a pair of compacting rolls, at least one of which is heated, before removing the web from the foraminous surface, said compacting rolls applying heat and pressure to the web sufficient to impart coherency thereto. If desired, one of the compacting rolls can be the forming drum or the forward drive and/or support roll for the continuous foraminous belt or wire screen, as appropriate.

The amount of pressure which is required generally is small, typically in the range of from about 5 to about psi. Preferably, the pressure applied by the compacting rolls will be in the range of from about 7 to about 13 psi. These pressure ranges, however, are given by way of suggestion only because the pressure employed is in part dependent upon the temperature of the at least one heated -26- -13compaction roll. The use of higher temperatures usually permits lower pressures and vice versa.

The temperature of the at least one heated compaction roll typically will be in the range of from about 27 to about 150° C. The preferred temperature range is from about 27 to about 70° C.

The at least one compaction roll can be heated by any means known to those having ordinary skill in the art.

For example, a heated fluid may be circulated through the at least one compaction roll. Alternatively, the surface of the at least one compaction roll may be irradiated by infrared heaters or lamps with appropriate surface temperature monitors in order to control the temperature of the roll.

Some aspects of the method of the present invention are described in more detail in earlier-referenced U.S.

a' a.

Patent Nos. 3,692,618 and 4,340,563, both of which are a' %o«o incorporated herein by reference.

o The present invention is further described by reference "Oo 20 to Figure 1B which is a generalized flow diagram illustrato4 ing a preferred embodiment of the spunbonding process of the present invention.

Turning now to Figure 1B, the thermoplastic composition is fed from supply 10 to hopper 12, then through extruder 14, filter 16, and metering pump 17 to die head 18 having die face 22 with a plurality of orifices arranged in .one or more rows qenerally in the cross-machine direction. As the continuous filaments emerge from die face 22, they form a curtain of filaments 20 directed into 30 quench chamber 24. In the quench chamber 24, filaments are contacted with air or other cooling fluid through inlet 26. The quenching fluid is maintained at a temperature which is lower than the temperature of the filaments typically at ambient temperature, in the range of from about 4 to about 55° C. The quenching fluid is supplied under low pressure, less than about 12 psi, -27- -14-

(J

and preferably less than about 2 psi, and a portion preferably is directed through the curtain of filaments 20 and removed as exhaust through port 28. The proportion of quenching fluid supplied that is discharged as exhaust will depend upon the composition being used and the rapidity of quenching needed to give the desired filament characteristics, such as denier, tenacity, and the like. In general, the greater the amount of fluid exhausted, the larger the resulting filament denier and, conversely, the lower the exhaust fluid ratio, the lowe'r the filament denier.

As quenching is completed, the curtain of filaments is directed through a smoothly narrowing lower end of the quenching chamber into nozzle 32 where the quenching fluid attains a velocity of from about 45 to about 245 meters per second. Nozzle 32 extends the full width of othe machine, equivalent to the width of die 22. Nozzle 32 4 preferably is formed by a stationary wall 34 and a movable o wall 36, both of which also span the width of the machine.

o 20 The function of movable wall 36 is described in said U.S.

0 Patent No. 4,340,563.

After exiting nozzle 32, filaments 20 are collected on a moving foraminous surface such as an endless screen or rci; belt 38 to form a nonwoven web 40. Before being removed 25 from belt or screen 38, web 40 is passed between compaction L irolls 42 and 44, optionally in conjunction with guide roll .46. Compaction roll 44 conveniently is the forward drive and/or support roll for the continuous foraminous belt or wire screen 38. Heat and pressure are applied to web 30 by means of compaction roll 42. Upon exiting compaction i rolls 42 and 44, web 40 now has sufficient coherency to permit further processing such as bonding at roll nip 48 and winding at Compaction roll 42, as already noted, n\ay be heated by any convenient means (not shown). For example, a heated fluid may be circulated through the at least one compaction -28roll as described in the Examples. Alternatively, the surface of the at least one compaction roll may be irradiated by infrared heaters or lamps with appropriate surface temperature monitors in order to control the temperature of the roll.

The Thermoplastic Composition Fibers formed from a thermoplastic composition described herein have a differential, increasing concentration of the additive from the center to the surface thereof, such that the concentration of additive in at least one of the interfacial surface, effective surface, and subsurface of the fiber is greater than the average concentration of additive in the core of the fiber, thereby imparting to the surface of the fiber at least one desired characteristic which otherwise would not be present.

As used herein, the term "surface" consists of the 4 a So interfacial surface and effective surface. The interfacial o surface in assence is the monomolecular layer of the fiber which is at the air/polymer (or nonfiber/fiber) interface.

The effective surface begins at the interfacial surface and extends into the fiber a distance of about 15 A. The subsurface lies below the effective surface and extends into the fiber to a depth of about 1,000 A; thus, the ,subsurface has a thickness of about 985 A.

The term "core" has reference to the remainder of the S" fiber which is not included in the surface and subsur- I face, that portion of the fiber which is below the subsurface. The term "bulk" refers to all of the fiber, the surface, subsurface, and core. The latter term 30 typically is used in reference to elemental analyses of Sthe fiber.

The surface-segregatable, melt-extrudable thermoplastic composition employed in the present invention comprises at least one thermoplastic polymer and at least one additive.

-29t 4 000 4 04 The term "'melt-extrudable" is equivalent to "meltprocessable" and is not intend.ad to be limited in any way.

That is, the term is intended to encompass the use of the composition in any melt-extrusion process which is or may be employed to prepare fibers, provided the process meets the limitations imposed by the claims. Thus, the term includes the use of the composition in melt-spinning of continuous filaments; meltblowing, spunbonding, and coforming of nonwoven webs; and the like.

In general, the term "thermoplastic polymer"~ is used herein to mean any thermoplastic polymer which can be used for the preparation of filaments (fibers) by melt extrusion.

Examples of thermoplastic polymers include, by way of illustration only, end-capped polyacetals, such as poly(oxymethylene) orpolyformaldehyde, poly (trichloroacetaldebyde), poly (ri-valeraldehyde) poly (acetaldehyde) poly (propionaldehyde) and the like; acrylic polymers, such as polyacrylamide, poly(acrylic acid), poly (methacrylic acid), poly- (ethyl acrylate), poly(methyl methacrylate), and the like; fluorocarbon polymers, such as poly (tetra fluoroethylene) perfluorinated ethylene-propylene copolymers, ethylenetetrafluoroethylene copolymers, poly (chlorotrifluoroethylene), ethyl ene-chi orotri fl1uoroethyl ene copolymners, poly- (vinylidene fluoride), poly(vinyl fluoride), and the like; polyamides, such as poly (6-aminocaproic acid) or poly(ccaprolactam), poly(hexamethylene adipamide), poly(hexa- ,methylene sebacamide), poly (1l-aminoundecanoic acid), and the like; polyaramides, such as poly (imino- 3-phenyleneininoisophthaloyl) or poly(M-phenylene isophthalamide), and the like; parylenes, such as poly-p--xylylene, poly- (chloro-p-xylylene), and the like; polyaryl ethers, such as poly (oxy-2 6-dimethyl-1, 4 -phenylene) or poly (p-phenylene oxide), and the like; polyaryl sulfones, such as poly(oxy- 1, 4 -p h enyl enesul fonyl 4-phenyl eneoxy- 14 -phenyleneisopropylidene-1 0 4-phenylene), poly (sulfolnyl-lp 4-phenyleneoxy-l, 4-phenylenesulfonyl-4 ,4 '-biphenylene), and the like; (i polycarbonates, such as poly(bisphenol A) or poly(carbonyldioxy-1, 4-phenyleneiscopropylidene-1,4-phenylene), and the like; polyesters, such as poly(ethylene terephthalate), poly(tetramethylene terephthalate), poly (cyclohexylene-1,4dimethylene terephthalate) or poly(oxymethylene-l,4-cyclohexylenemethyleneoxyterephthaloyl), and the like; polyaryl sulfides, such as poly(R-phenylene sulfide) or poly(thio- 1,4-phenylene), and the like; polyimides, such as poly- (pyromellitimido-1,4-phenylene), and the like; polyolefins, such as polyethylene, polypropylene, poly(l-butene), poly(2-butene), poly(1-pentene), poly(2-pentene), poly(3methyl-l-pentene), poly(4-methyl-1-pentene), 1,2-poly-1,3butadiene, 1, 4-poly-1, 3-butadiene, polyisoprene, polychloroprene, polyacrylonitrile, poly(vinyl acetate), poly(vinylidene chloride), polystyrene, and the like; copolymers of the foregoing, such as acrylonitrile-butadiene-styrene n (ABS) copolymers, and the like; and the like.

7, The preferrAd polymers are polyolefins and polyesters, o with polyolefins being more preferred. Even more preferred are those polyolefins which contain only hydrogen and carbon atoms and which are prepared by the addition polymerization of one or more unsaturated monomers. Examples of such polyolefins include, among others, polyethylene, $f 25 polypropylene, poly(l-butene), poly(2-butene), poly(1pentene), poly(2-pentene), poly(3-methyl--pentene), Spoly(4-methyl-l-pentene), 1, 2-poly-i, 3-butadiene, 1,4poly-1,3-butadiene, polyisoprene, polystyrene, and the like. In addition, such term is meant to include blends of two or more polyolefins and random and block copolymers prepared from two or more different unsaturated monomers.

Because of their commercial importance, the most preferred polyolefins are polyethylene and polypropylne.

-Broadly stated, the additive must have at least two moieties, A and B, in which: said additive is compatible with said polymer at melt extrusion temperatures but is incompatible at temper- -31f atures below melt extrusion temperatures, but each of moiety A and moiety B, if present as separate compounds, would be incompatible with said polymer at melt extrusion temperatures and at temperatures below melt extrusion temperatures; and moiety B has at least one functional group which imparts to said polymeric material at least one desired characteristic.

Because the additive is compatible with the polymer at melt extrusion temperatures, the additive is miscible with the polymer and the polymer and the additive form a metastable solution. The solution formed by the additive and the polymer at temperatures above melt extrusion temperatures is referred to herein as a metastable solution since the solution is not stable at temperatures below melt extrusion temperatures. As the temperature of the D0 o newly formed fiber drops below melt extrusion temperatures, :0 the polymer begins to solidify which contributes to additive 0oo 0 separating from the polymer phase. At the same time, the 0 o 20 additive becomes less compatible with the polymer. Both o factors contribute to the rapid migration or segregation of additive toward the surface of the newly formed fiber which occurs in a controllable manner.

This preferential migration or segregation is controllable because the extent or degree of migration is, at least in part, a function of the molecular weight of the additive, the shear rate, and the throughput. While the mechanism of additive migration or segregation is not fully understood, it appears that the rate of migration or segregation is: indirectly proportional to the additive molecular weight the higher the additive molecular weight, the slower the rate of segregation; directly proportional to the shear rate the higher the shear rate, the faster the rate of segregation; and -32made in accordance with the present invention, in which -19indirectly proportional to throughput the higher the throughput, the slower the rate of segregation.

There are at least three very surprising and unexpected aspects to the segregation phenomenon. The first is that the additive as defined herein is compatible with the polymer at melt extrusion temperatures, given the fact that moieties A and B, if present as separate compounds, would be incompatible with the polymer at any temperature.

The second is that lower molecular weight additives perform better than higher molecular weight additives; this is contrary to the conventional wisdom of polymer additives which favors higher molecular weights. The third and perhaps most startling aspect is the rapidity with which such segregation takes place.

As just noted, the effect of additive molecular weight on the rate of segregation was surprising, especially a "4 in view of past experiences with polydimethylsiloxane.

S" Upon reflection, it now appears that the movement of lower o*°f 0 molecular weight additives through the gradually solidifying 20 polymer is roughly analogous to the movement of small .or particles through a viscous fluid the larger the parti- S cles, the greater the resistance to movement through the fluid. This analogy seem appropriate since it has been demonstrated that the additive exists as small globules in 25 the polymer, which globules become smaller as the temperature of the molten composition increases. By imposing shear I .forces on the molten composition, the globules are broken down into smaller globules far more quickly than would have occurred in the absence of shear. Thus, shear is a contributing factor which enhances the segregation of the additive to the surface of the newly formed filament.

In general, the shear rate will be in the range of from about 50 to about 30,000 sec 1 Preferably, the shear rate will be in the range of from about 150 to about 5,000 sec 1 and most preferably from about 300 to about 2,000 sec-l.

-33- It perhaps should be mentioned at this point that the compatibility requirement is critical. That is, if the additive is not compatible with the polymer at melt-extrusion temperatures, the composition cannot be melt processed to give satisfactory filaments.

By way of clarification, it already has been noted that compounds such as polydimethylsiloxane have been incorporated in polymers which were extruded, but not melt processed to give fibers. Such compounds migrated to the surface of the extruded article to provide a lubricated surface to aid further processing or removal from a mold. Because extrusion times were very slow compared to the melt processing times typically experienced in fiber formation, migration or segregation rates were not an issue. However, the incompatibility of the added compounds prevents acceptable melt-processing because of discontinuities in fiber formation. In addition, such compounds often reduce friction o within the extruder to the point that the molten mixture 4° 0 rotates essentially as a plug with no downstream movement taking place.

9 Finally, throughput is of importance because it o affects the time the newly formed filament is in a sufficiently molten or fluid state to allow migration or segregation of the additive to the newly formed surfaces, even 25 though throughput also affects the shear rate. Stated s differently, it is possible to control the rate of migration 0, 00 or segregation by controlling the rate of cooling of the newly formed filament. Thus, for any given molecular weight additive, the extent of migration can be reduced by rapidly 0 0 30 cooling the filament. Alternatively, migration can be enhanced by reducing the rate of cooling.

SO" Throughput typically will be in the range of from about 0.01 to about 5.4 kg/cm/hour. preferably, throughput will be i!,i the range from about 0.1 to about 4.0 kg/cm.hour.

The throughput most preferably will be in the. range of from about 0.5 to about 2.5 kg/cm/hour.

-34- As used herein, the phrase "molten state" does not necessarily mean "flowable". Rather, the term is used to denote a condition of the thermoplastic composition in which the additive molecules still are capable of migrating or segregating to the surface of the newly formed filament.

Thus, the term is somewhat imprecise and not readily subject to accurate measurement. Consequently, this composition fluidity factor preferentially is described or accounted for by the term "throughput".

The controlled migration or segregation of additive toward the surface of the filament results in a controllable differential concentration of additive in the filament. If measurable migration is allowed to occur, the concentration of the additive in the filament will increase with increasing distance from the center thereof. By the proper selection of additive, additive molecular weight, shear rate, and throughput (or rate of cooling), a substantial amount, or perhaps even all, of ths additive can be found 00°% 0 in the surface. Because the concentration of additive in 0 4 the core of the filament typically will vary nonlinearly

S

t from the concentration of the additive in the surface, o 2" this concentration difference is referred to herein as a differential concentration.

4 ,**&,While the additive can be either a liquid or a solid, a liquid is preferred. It also is preferred that a liquid 4 4* additive have a surface tension which is less than that of n ;..virgin polymer; the lower surface tension assures that the additive will be more likely to completely "wet" or cover the surface of the filament as the segregation process proceeds to completion, especially under conditions favoring a large concentration differential.

As already noted, additiv surface segregation is influenced by the molecular weight of the additive. More specifically, the lower the molecular weight of the additive, the more rapid is the rate of segregation of the additive to the surface of the filament at any givon i I ii 1 4a 0 4 a*4 04P 40 4 l) 0£ 4 0 44O o QO 08 40 1 4 4 Ot 4 4 4£ 44~ 4 4 41 44 4 4 44 £4 44 £4 4 I 4 temperature at which the filament still is in a sufficiently molten state.

It should be apparent that the additive can be monomeric, oligomeric, or polymeric. Indeed, polymeric additives are required in order to achieve the higher additive molecular weights permitted by the present invention.

Because lower additive molecular weights are preferred, the preferred additives perhaps are properly referred to as oligomers. However, such nomenclature can be misleading and reliance instead should be placed on the molecular weight of the additive and the other parameters already described. It is for this reason that the additive is not referred to as a polymeric additive, even though in many instances the additive will be oligomeric or polymeric in nature.

As already stated, the additive molecular weight will be in the range of from about 400 to about 10,000. This range encompasses suitable additive molecular weights, regardless of whether the additive is to be used by itself 20 or in a mixture of additives; the additive molecular weight range depends in part on whether or not an additive will be used by itself.

Accordingly, the molecular weight range for additives which are to be ased individually in compositions for 25 filament formation and not as part of a mixture of additives typically is from about 400 to about 3,000. Preferably, .this range is from about 500 to about 2,000, and more preferably from about 500 to about 1,500. The most preferred range is from about 500 to about 1,000.

30 When additives are intended to be used in a mixture, however, higher molecular weights can be employed. Although the reasons for this are not clearly understood, mixtures of additives frequently are more compatible with the polymer at melt-extrusion temperatures than are the individual additives. Although the selection of additive mixtures is somewhat empirical, in general such mixtures I t~I -36i:-i -1 ._il can utilize additives having molecular weights in the range of from about 400 to abkiou 10,000 and preferably from about 400 to about 8,000.

In this regard, some clarification of the term "used successfully" is necessary. The successful use of an additive or a mixture of additives has reference to two factors. First, the additive or additive mixture must segregate to the target zone in order to achieve the intended properties. For example, if water-wettable filaments are desired, the additive or additive mixture must segregate to either or both of the interfacial surface and the effective surface of the filaments. Second, the composition containing the additive or additive mixture must process well enough in commercial-scale spunbonding equipment to give a web or fabric having the required aesthetic and physical properties.

It should be noted that the foregoing molecular weight SIo* ranges are based on the assumption that oligomeric or 4 polymeric additives will have relatively broad polydispersities, of the order of about 1.2. While narrow o r polydispersities certainly are achievable, usually at a higher cost, they are not necessary, even if relatively low molecular weight additives are to be employed, As a guideline, it may be noted that for a given additive, the S8 25 average molecular weight of an additive having a narrower polydispersity usually should be slightly lower than the SOOo *,average molecular weight of an additive having a broad polydispersity. While this guideline is not precise and is somewhat empirical in nature, one skilled in the art so 30 will be able to properly select an additive of any polydis- *persity without undue experimentation.

rThe term "additive" is used broadly herein to encompass the use of two or more additives in a given composition.

Such two or more additives may have the skme or similar moieties B, or different moieties B having the same characteristic, water wettability. On the other hand, two -37- -24or more additives may be used which have different characteristics, which characteristics may be related or unrelated. Such two or more additives may be present in sit.ilar or significantly different amounts. Moreover, the additives may have the same or similar molecular weights in order to segregate in the filament to approximately the same region. Alternatively, different molecular weight additives may be employed in orde to effectively layer the additives in -ne surface.

1G The use of different molecular weight additives is especially attractive for some characteristics which reinforce each other, an example of which is the use of a first additive having a moiety B which is an absorber of ultraviolet radiation and a second additive having a light stabilizing or degradation inhibiting moiety B which functions by deactivating excited oxygen molecules or terminating free radicals. The first additive normally o, .will have a lower molecular weight than the second. While 4 both additives segregate to the surface, the first additive o" a 20 migrates primarily to the effective surface, while the Ssecond additive migrates primarily to the subsurface.

Thus, actinic radiation which is not absorbed by the first additive is effectively nullified by the second additive.

The result is a complimentary or even synergistic effect which is greater than that which would be achieved if the two additives were commingled in the same region.

The additive is a material which will be referred to he:ein loosely as a siloxane. Hence, moiety A will comprise at least one tetrasubstituted disiloxanylene group, option- 30 ally associated with one or more groups selected from the gro'lp consisting of trisubstituted silyl and trisubstituted siloxy groups, the substituents of all such groups being independently selected from the group consisting of monovalent alkyl, cycloalkyl, aryl, and heterocyclic groups, each of which is substituted or unsubstituted.

As a practical matter, moiety A often will consist of all -38three groups. Moreover, more than one tetrasubstituted disiloxanylene group often will be present, particularly when the additive has an appreciable molecular weight.

As used herein, the term "tetrasubstituted disiloxanylene group" means a group having the following general formula:

R

33

R

3 I I -Si-o-Si- I I

R

34

R

36 0 0 00 04 00 O 004) t0o 0 4 1 4 4 Os 0 04 4 *0 4 00 B0 OD 4 tt tG 0n in which each of R 33

-R

3 6 inclusive, is a monovalent group independently selected from the group consisting of alkyl, cycloalkyl, aryl, and heterocyclic groups.

As noted, the substituents of the groups comprising moiety A can be alkyl, cycloalkyl, aryl, or heterocyclic groups which are the same or different and which in turn are substituted or unsubstituted. Other than the obvious 20 requirement that such substituents not adversely affect additive stability or other properties, there are no known limitations to such substituents. However, for reasons relating primarily to commercial availability and ease of synthesis, such substituents preferably are alkyl groups 2 and more preferably are unsubstituted alkyl groups having from 1 to 3 carbon atoms. Most preferably, such substituents are methyl groups.

More specifically, the additive preferably contains a plurality of groups selected from the group consisting of th following general formulae, it being understood that not all groups need to be present and that the presence of some groups precludes the presence of others:

B

5

B

6

R

1 3

R

1 4 -Sim (RI5)(RI6) R17) Si- -39i i 1

(R

8 (Ri 9

(R

2 0 )Si-O-, [-Si(R 2 1 (R 2 and [-Si(R 2 3 in which each of R 13 and Ri4 independently is a monovalent group selected from the group consisting of hydrogen, alkyl, cycloalkyl, aryl, and heterocyclic groups, each of which, except for hydrogen, is substituted or unsubstituted; each of R 15

-R

1 7 inclusive, independently is a monovalent group selected from the group consisting of alkyl, cycloalkyl, aryl, and heterocyclic groups, each of which is substituted or unsubStituted, and B 8 each of R 1 8

R

2 3 inclusive, independently is a monovalent group selected from the group consisting of alkyl, cycloalkyl, aryl, and t* heterocyclic groups, each of which is substituted or o B 15 unsubstituted; each of a and b independently represents an integer from 0 to about 70 which indicates only the quantity S«of the respective group present in the additive without indicating or requiring, in instances when an integer is greater than 1, that such plurality of the respective group are connected to one another to form an oligomer or polymer or that all of such groups have identical substituents; and each of B 5

-B

8 inclusive, independently is a moiety which imparts to the additive at least one desired characteristic; with the proviso that such plurality of r° 25 groups results in at least one tetrasubstiLuted disiloxanylene group.

Molecular weight limitations, if desired, are readily o|o achieved by limiting the sum of a and b to the extent required to achieve the desired molecular weight.

In general, the preparation of the siloxane moiety is well known to those having ordinary skill in the art.

Siloxanes that have reactive groups, such as H-Sia, RO- Sim, and Cl-Sim, are used as starting products. Such materials are prepared either by hydrolysis of, e.g., methylchlorosilanes or by copolymerization of cyclic or linear polymethylsiloxanes with functior siloxanes.

~.Li L See, for example, W. Noll, "Chemistry and Technology of Silicones," Academic Press, New York, 1968; and R. Meals, "Encyclopedia of Chemical Technology," Vol. 18, 2nd Edition, 1969, p.221.

Turning now to moiety B, it is this moiety which must have at least one functional group which imparts to the additive at least one desired characteristic. Because the additive rapidly migrates or segregates toward the surface of the filament upon its formation, it io the presence of moiety B in the surface of the filament which results in such surface acquiring the at least one characteristic of moiety B. Such at least one characteristic clearly would not be found in the surface of the filament in the absence o" OP of the additive. Examples of such characteristics include, by way of illustration only and without limitation, wett- 'ability by water or other polar solvents, preferential o* wettability by alcohols, enhanced hydrophobicity which SO contributes to a nonstaining surface, and stability to actinic radiation, especially ultraviolet radiation.

It perhaps should be noted at this point that the term "functional group" refers to that portion of moiety B which imparts the desired at least one characteristic; the term is not to be equated to "reactive", although a group which also is reactive is not precluded by the term "functional group".

Moiety B need not be limited to a single desired •characteristic. Alternatively, the additive can contain two or more moieties B which have different characteristics.

For example, a moiety B may have a wettable group and a group which is stable to actinic radiation or a group which absorbs ultraviolet radiation and a group which inhibits actinic radiation-induced degradation, or one moiety B may have a wettable group while a second moiety B is stable to actinic radiation.

The point of attachment of moiety B to moiety A is not known to be critical. For example, when moiety A is a -41-

J

siloxane, moiety B can be a substituent of any one or more of the tetrasubstituted disiloxanylene, trisubstituted silyl, and trisubstituted siloxy groups which may be present.

Those having ordinary skill in the art, upon determining the characteristic or characteristics desired for any given additive, will know what functional group or groups may be required for moiety B. In other words, the selection of functional groups is well within the abilities and understanding of one having ordinary skill in the art in view of the teaching herein. In order to illustrate the principle involved, though, a preferred embodiment for moiety B when the desired characteristic is water wettability will be described in detail.

S 15 To obtain a filament having a surface which is water wettable, moiety B preferably is a poly(oxyalkylene) moiety. More preferably, the alkylene portion of such moiety will contain from 2 to about 6 carbon atoms. Most preferably, moiety B is a poly(oxyalkylene) moiety in 20 which the oxyalkylene repeating units are oxyethylene or oxypropylene or a mixture thereof.

~References which disclose polysiloxanes containing one or more poly(oxyalkylene) moieties suitable for use as the additive include, among others, U.S. Patent Nos.

2,836,748, 2,917,480, 2,991,300, 2,991,301, 3,168,543, 3,172,899, 3,236,252, 3,278,485, 3,280,160, 3,299,113, 3,356,758, 3,402,192, 3,480,583, 3,505,377, 3,509,192, too 3,530,159, 3,600,418, and Re. 27,541; Belgian Patent No.

627,281; British Patent Nos. 892,819, 954,041, 963,437, 30 981,811, 981,812, 1,073,368, and 1,098,646; French Patent Nos. 1,259,241, 1,356,962, 1,411,757, 1,413,125, 1,482,133, 1,511,661, 1,520,444, and 1,179,743; German Published Specification (Offenlegungschrift) Nos. 1,495,927, 1,570,656, 1,595,730, 2,045,360, and 2,555,053; German Patent Nos.1,235,594, 1,257,433, 1,301,576, 1,570,647, and 1,195,953 -42- By way of illustration only, three types of additives for imparting water wettability to the surfaces of filaments, referred to hereinafter as types A, B, and C, respectively, are described below with reference to the plurality of preferred groups described earlier. In each case, moiety B is an oxyalkylene-containing moiety which is represented by the following general formula:

-(CH

2 x-0- (H 4 (CH40)(C 3

H

6 0)-R 2 6, 99 9 99 9 9 9 9s 9 99 9 9 9a 9*99 99 9 in which R 2 6 is a monovalent group selected from the group consisting of hydrogen and lower alkyl; x represents an integer from 0 to about 3; and each of y and z independently represents an integer from 0 to about 70 which indicates only the quantity of the respective group present in the additive without indicating or requiring, in instances when an integer is greater than 1, that such plurality of the respective group are connected to one another to form an oligomer or polymer.

20 Type A Additives The first type, which is most preferred, consists of groups of formulae 1, 2, and 7, in which each of R 9 and

R

1 0 independently is an alkyl group containing from 1 to 3 carbon atoms; R 2 6 is an alkyl group containing from 1 to 4 carbon atoms; a is in the range of from 3 to about 60; x is 0; y is in the range of from about 5 to about and z .is in the range of from about 0 to about Specific examples of type A additives, by way of illustration only, include materials having the following 30 general formula: 9940 9 9 9990 *9 90 9n 9 9

CH

3

B

9 -0-(-Si-0-)g-B9

I

CH

3 -43in which B9 is -(C 3

H

6 0)h(C 2

H

4 0)i-R 27 and R 27 is hydrogen or a lower alkyl group.

Commercially available additives of this type include TEGOPREN BC-1781, in which g has an average value of R27 is n-butyl, and the ethylene oxide/propylene oxide weight percent ratio in B 9 is 40/60; TEGOPREN D-985, in which g has an average value of 4.3, R 2 7 is methyl, and the ethylene oxide/propylene oxide weight percent ratio in 89 is 70/30; and TEGOPREN V-337, in which g has an average value of 4, R 27 is methyl, and the ethylene oxide/propylene oxide weight percent ratio in B 9 is 100/0.

Type A additives in general are prepared by heating silicon with, chloromethane in the presence of a copper catalyst at about 300° C to give dichlorodimethyl silane (see, U.S. Patent No. 2,380,995 to E. G.

S*Rochow) which, when reacted with water, gives a polymer S\ having the following general formula: S20

CH

3 CH 3 CH3 0 0 I I I Cl-Si-0-(S -Si-Cl,

CH

3

CH

3

CH

3 Swhere j is an integer representing the number of repeating units in the molecule. See, for example, B. B. Hardman LL 25 and A. Torkelson, "Encyclopedia of Chemical Technology," 3rd Edition, John Wiley Sons, Inc., New York, 1982, pp.

922-962. The polymer then is reacted in the presence of trifluoroacetic acid with an oxyalkylene-containing compound Shaving the general formula,

HO-(C

3

H

6 0)y(C 2

H

4 0)z-R26 in which R 26 y, and z are as already defined, to give the additive. See U.S. Patent No. 2,836,748. See also U.S.

Patent No. 2,917,480, U.S. Patent No. 3,505,377, And German Patent No. 1,259,241.

-44- JLI=.. tUrJ.UzHIjLU L jtju 1z.Ue5 sju1 Lin;mFX-IjIe a& emper- -31formulae 5-8, inclusive, in which each of R 3

-R

11 inclusive, independently is an alkyl group containing from 1 to 3 carbon atoms; R 26 is an alkyl group containing from 1 to 4 carbon atoms; a is in the range of from about 3 to about 30; b is in the range of from about 1 to about 10; x is 3; y is in the range of from about 5 to about 25; and z is in the range of from about 0 to about Specific examples of type B additives, also by way of illustration only, include materials having the following general formula:

CH

3

CH

3 CH 3 CH3 i I I H3C-Si-O- k- (-si-O-)1si-CH3

CH

3

CH

3 810 CH 3 4. 4 Sin which 10 is -(CH3) 3O-(C 2 H 4O)m(C3H 6 0n 2 8 and R28 is hydrogen or a lower alkyl group.

Commercially available examples of this type include SILWET L-77, SILWET L-7500, and SILWET L-7602 (Union Carbide Corporation, Danbury, Connecticut). Other commer- 4ot cially available examples include TEGOPRN 5843, in whxIh the k/ value is 13/5, R 28 is hydrogen, nd the ethylene 44oxide/propylene oxide weight percent ratio in B10 is 100/0; TEGOPRENr 5847, in which the k/l value is 0/1, R 28 is hydrogen, and the ethylene oxide/propylene oxide weight °percent ratio in B10 is 80/20; TEGOPREN 5852, in which S0 the k/l value is 20/5, R 2 8 is hydrogen, and the ethylene oxide/propylene oxide weight percent ratio in B 10 is 20/30; TEGOPREN 5863, in which R 2 8 is hydrogen and the ethvl4ne oxide/propylene oxide weight percent ratio in B10 is 40/60; TEGOPREN 5873, in which the k/1 value is 20/5, R 28 is hydrogen, and the ethylene oxide/propylene oxide weight percent ratio in Bi0 is 35/65; and TEGOPREN 5878, in which

R

28 is hydrogen and the ethylene oxide/propylene oxide weight percent rt..o in B 10 is 100/0 (Th. Goldschmidt AG, Essen, Federal Republic of Germany).

The synthesis of the type B additives begins with a reactive silicon fluid, prepared by known methods, such as that represented by the following formula:

CH

3

CH

3

CH

3

CH

3 I I I I H3C-Si-0-(-Si-O-)k-(-Si-O-)1-Si-CH3 I I I I

CH

3

CH

3 H CH 3 in which k and 1 are as already defined. The fluid is reacted with a compound having the general formula, 0 0 CH2=CHCH 2

-O-(C

2

H

4 0)m(C 3 H60)nR28 in which R 28 m and n are as already defined, to give the o additive. The reaction is carried out in the presence of 0 0 a platinum/r-aluminum oxide catalyst at a temperature of So the order of 150° C. See, U.S. Patent No. 3,280,160, 20 U.S. Patent No. 3,172,899, and US. Patent No.3,505,377.

The compound which is reacted with the silicone fluid is obtained by the condensation of ethylene oxide and propylene oxide with allyl alcohol in the presence of a catalytic 2 amount of potassium hydroxide, a well-known reaction.

<25 Type C Additives The third, and last, type of additives consists of groups of formulae 2, 4, and 7, in which each of R 2

R

9 and R 10 independently is an alkyl group containing from 1 to 3 carbon atoms; R 26 is an alkyl group containing from 1 30 to 4 carbon atoms; a is in the range of from 0 to about x is 0; y is in the range of from about 5 to about and z is in the range of from about 0 to about Specific examples of type C additives, again by way of illustration only, include materials having the following general formula: -46sec-1 sec -33-

CH

3

R

29 -Si[(-0-Si-)g-(OC 2

H

4 )p(OC3H6)q-OR3 0 o]3 I

CH

3 in which R 29 and R 30 are lower alkyl groups, g is as already defined, and each of p and q represents an integeic from 0 to about A specific commercially available example is SILWET L-720 (Union Carbide Corporation, Danbury, Connecticut).

When the desired characteristic of the additive is ultraviolet light absorption, moiety B is a chromophore, especially a chromophore having a sufficiently high efficiency for the absorption of ultraviolet radiation.

°or Preferably, moiety B is a benzotriazolyl group, most 15 so prefe:ably a 2-(substituted-phenyl)benzotriaZolyl group.

Moiety B is a degradation inhibitor when the desired characteristic of the additive is light stabilization.

Preferably, such inhibitor contains a piperidyl group. Most preferably, such inhibitor contains a polyalkyl-substituted 20 piperidyl group.

o0, When a nonstaining or low surface energy filament is 44t desired, a filament having a hydrophobicity which is higher than that of the virgin polymer component of the Scomposition, moiety B conveniently can be a perfluoro- 4 25 hydrocarbon group, any number of which are known to those ,having ordinary skill in the art. Also known to those 4 4 having ordinary skill in the art are groups which can be 'I use as moiety B in order to impart a buffering capacity to the filament, such as a buffering capacity against hydrogen ions. In view of the teachings herein, other possible characteristics of moiety B will be readily apparent.

In general, the weight ratio of polymer to additive can vary from about 10 to about 100. That is, the amount of additive in the surface-segregatable, melt-extrudable composition of the present invention thermoplastic composition of the present invention can -47i range from about 10 percent by weight to about 1 percent by weight.

The thermoplastic composition can be prepared by any number of methods known to those having ordinary skill in the art. For example, the polymer in chip or pellet form and the additive can be mixed mechanically to coat the polymer particles with additive. If desired, the additive can be dissolved in a suitable solvent to aid the coating process, although the use of a solvent is not preferred.

The coated polymer then can be added to the feed hopper of the extruder from which the filaments will emerge. Alternatively, the coated polymer can be charged to a heated compounder, such as a heated twin-screw compounder, in order to disperse the additive throughout the bulk of the or S 15 polymer. The resulting thermoplastic composition typically is extruded as rods which are fed to a chipper. The 4 o resulting chips then serve as the feed stock for a meltprocessing extruder. In another method, the additive can be metered into the throat of the hopper which contains the polymer in particulate form and which feeds the extruder. In yet another method, the additive can be metered s directly into the barrel of the extruder where it is blended with the molten polymer as the resulting mixture 4 0 moves toward the die.

S 25 The present invention is further described by the examples which follow. Such examples, however, are not to .be construed as limiting in any way either the spirit or ooo scope of the present invention, especially since the experimental work concentrated on (but is not limited to) 44 4 imparting wettability to polyolefin filaments. In the examples, all temperatures are in degrees Celsius and all parts are by weight unless stated otherwise.

-48- Examples For convenience, the examples are divided into six sections describing the additives and polymers employed; the preparation of surface-segregatable, melt-extrudable thermoplastic compositions; the preparation of meltpressed films from the thermoplastic compositions; the preparation of fibers from the thermoplastic compositions; evaluation of a known material as an additive by way of comparison; and a hot-stage microscope study of a composition described in U.S. Patent No. 4,070,218.

I. Descriptions of Additives and Polymers A. Additives Each of the additives employed in the examples was a 4 t S 15 type A, B, or C additive. The structures imparting water wettability are identified in Tables 1, 3, and 5 ("MW" I 4 represents molecular weight); if an additive were commerat 0 cially available, the material designation or catalog t number is given in the column labeled and a manufac- S 20 turer code is given in the column labeled "Source". The properties of the additives identified in Tables 1, 3, 00 and 5 are summarized in Tables 2, 4, and 6, respectively.

4 The structures of additives imparting characteristics other than water wettability are given in Tble 7 and their 25 properties are summarized in Table 8.

4 1 Table 1 Type A Additives Imparting Water Wettabilitv CH3

R

27 0

-(C

2

H

4 0)i(C 3

H

6 0)h-(-SiO-)g (C 3 H60)h(C2H40)i-R27

I

CH

3 Additive Code -B27- h -h MW Source AOl CH 3 3 0 3 516 V-363 Ga A02 CH 3 3 0 3 516 V-360 G -49dividual additives. Althougn tne selection or aualTu ve mixtures is somewhat empirical, in general such mixtures -36ii A03 A04 A06 A07 A08 A09 All A12 A13 A14 A16 15 A17 A18 A19 A20 A21 A22 A23 A24

CH

3

CH

3

CH

3

CH

3

CH

3

CH

3

CH

3

CH

3

CH

3

CH

3

CH

3

CH

3

CH

3

CH

3

CH

3 NAc

CH

3 n-C 4

H

9

NA

CH

3

NA

H

4 0 3 590 V-361 3 4 4 3 4 3 4 4 4 4 4 4.3 5.7 4.3

NA

5.5 5.5

NA

6 6 60 0 0 0 1.5 1 1.5 1 1.5 1.5 1.5 0 1.5 1.5 1.5 0 1.5

NA

NA

NA

NA

17 4 4 4 3 3 4 4 4 4 4 6 5 5 7.5

NA

7.5

NA

NA

NA

NA

16 604 678 678 690 706 778 794 852 852 352 854 1023 1127 1130 1200 1200 1450 2400

NA

NA

7922 V-336 KC-V2b V-337 V-362 V-3003 V-338 KC-V3 b T-3004 V-339 V-335 KC-V4 D-985 D-984 D-979 PS-071 D-978 BC-1781 PS-555 V-284 V-290 T-5830

G

G

G

G

G

G

G

G

G

G

G

G

G

G

G

UCd

G

G

UC

G

G

G

o oa 0 00 S0 oa o 0 00 aTh. Goldschmidt AG, Essen, Federal Republic of Germany.

bSynthesis utilized a purer polyether.

CNot available.

dunion Carbide Corporation, Danbury, Connecticut.

0000 0 0 0O '0 0) Table 2 Properties of the Type A Additives of Table 1 Code A01 A02 A03 A04 VisCositya 7 10 11 16 Cloud Pointb NAd 1 7 surface Tensionc 24.9 24.4 22,5 24,2 13 <0 23.5 A06 15 2 23.4 A07 18 7 26.0 A08 15 <0 NA A09 17 4 25.2 24 <0 24.3 All 23 <3 25.2 A12 16 2 22.8 A13 18 2 24.3 A14 22 15 23.9 A115 26 22 NA A16 31. 21 NA A17 58 45 25.8 A1.8 20 20 NA A19 59 40 24.0 A20 40 0 24.9 A21 320 NA NA A22 38 4 22.8 A23 44 4 24.3 A24 2400 Te 21,u amn centistokes at 251 C.

b 1 n degr~ees C, of a 3. percent by weight aqueous solution.

Oln dynes/nu, k 1.6i, of a I. percent by Weight aqueous solution.

dNot available.

eTurb id t

C

CC

C

C C C C CC CC C C C C o ~'o 0* CC C o o 00CC C C C Co I C CI CC C 0* CC CC C Q C C '1 C CC i -51- Tablo 3 Tpe B Additives Impartinc Water Wettabil ty

CH

3

CH

3

CH

3

CH

3 I I I I

H

3 k(-Si-O-) 1 -Si-CH 3 I II CH3 CH 3

CH

3

(CH

3 3

-C>(C

2

H

4 0) m(C3H60) nR 2

B

Additive Code -j8-

BO

B02 B03 B04 B05 B06 B07 B08 B09 20 BlO Bll

CH

3

H

CH

3

CH

3 n-C4

H

9

H

H

H

H

H

H

k 1 m NAa NA NA 0 1 10 0 2 10 NA NA NA NA NA NA 18 5 12 20 5 3 20 5 1.3 18 5 16 20 5 8 43 5 22 n MW D.

NA 600 L-77 2 836 T-5847 2 850 T-5878 NA 3000 L-7602 NA 3000 L-7500 0 4724 T-5842 10 5792 T-5852 3 5962 T-565 2 6184 T-5857 12 7472 T-5373 23 15t444 T-5863 Source UCb Gc

G

UC

Uc

G

G

G

G

G

G

,4 4 1 4.

4 44 44 44 4I 4 4 0 44 4 44 4 4 aNot available.

bUnion Carbide corporation, 2Th. Goldschridt AG, lssen, Danbury, Connecticut, Federal Republio of Germany.

Table 4 Properties of the Type B Additives cf Table 3 S.de 8Ol B02 B03 B04 05 B06 Viscositva 20 100 25 1Q0 175 560 Cloud Pointb 10 45 T9 0 Ih 80 Refractive Indexc NAd

NA

1.446

NA

NA

1.450 Surface Tension 21e 23f 2rf

NA

3 0 f -52- B07 290 10 1.444 NA B08 430 65 1.450 30 f B 09 580 84 1.449 28 f 440 30 1.449 28 f B11 2700 42 1.450 30 f amn centistolces at 25* C.

b 1 n degrees C, of a 1 percent by weight aqueous solution.

CAt 20* C, 0.005.

dNot available.

emn dynes/cm, 1.5, of a 0.1 percent by weight aqueous solution.

f~ dynes/cm, 1.5, of a 1 percent by weight aqueous solution.

gTurbjd.

hInsoluble.

Table Wpe C Additive Imipartini Water Wettability

CH

3 Add, d R -29- 30- .l MW I.D. Source 4 C,8l 14 4 9 A NA NA 8000 L"720 ucb aNot available.

ThuionCarbide corporation, Danbury nnecticut.

Table 6 Prprties of the Type C Additive of T ble 3 Cloud R~af ract ive Siarface gode Viscositva Pointb I dexc Tensiond COl 1100 42 NAe 2 amn centistokea at 250 C.

b 1 n degrees C, of a I percent by weight aqueous solution.

-53linear polymethylsiloxanes with functior slxns siloxanes.

CAt 20* C, 0.005.

d 1 n dynes/cm, 1.5, of a 0.1 percent by weight aqueous solution.

eNot available.

Table 7 Additives Imlparting Characteristics other Than Water Wettabilitv Additive Code DOla,b 0 0 0 0 0 0 0 00 0 0~ 0 On 0 On 0 0 0 0 00 o '~4 0~

C.

DO

2 c,d Structure CH1 3

CH

3

(CU

3 3 Si- 4 -0-Si-O-Si(CH 3

)I

I I

U

3 (CUr 2 3

CHOU,

CH

2

R

31

CH

3

CU

3 I I.

(CH

3 3 Si- 4 -0-Si-O-Si(CH 3 3 I I

CU

3

(CU

2 3

CHQH

CF

2

R

3 2

CH

3

(CU

3 3 4 -Si (CU 3 3 k 2 3 0

CH-CH

2

-NCCH(CH

3 2

OH

Source Ex. 1 EX. 2 DO3e -54not known to be critical. For example, when moiety A is a -41-

CH

3 D049 (CH 3 3 Si-O-(Si-0-) 32 -Si(CH 3 3

CH

2

CH

2

C

3

CH

3 DO5i (CH 3 3 Si-O-(Si-0-) 122 -Si(CH 3 3 p I

CH

3 almparts ultraviolet radiation absorption.

bR 3 1 is 2-(2-hydroxy-3-jt-butyl-5-methylp~henyl)-2H-benzotriazol-5-yl, lithium salt.

clmparts light stabilization by deactivating excited oxygen molecules or terminating free radicals.

hydroxyp iper idyl succinate) covalently coupled through an ether linkage via the 4-hydroxy group of the tei~inal piporidyl moiety.

eImpazrts buffering capacity igainst hydrogen ions.

fD-los9, Th. Goldschmidt AG, Essen, Federal Republic of Germany.

gImparts a low surface energy.

hpS-1 82 Petrarch Systems, Bristol, Pennsylvania.

1 A control additive which lacks a moiety B.

JPS-042, Petrarch Systemp, Brlstol, Pennsylvania.

'able 8 Properties of the Additives of Table 7 Refractive surface Code Viscosity'Idx Tension 0 D01 NAd NA NA D02 NA NA NA -i D03 NA NA NA D04 1,000 1.382 NA DOS 500 1.403 21.1 aIn centistokes at 25° C.

bAt 20° C, 0.005.

cIn dynes/cm, dNot available.

Example 1 Preparation of Additive DO1 A 100-ml, three-necked, round-bottomed flask was fitted with a pressure-equalized side arm addition funnel, condenser, and rubber seiptum. The addition funnel and O 15 condenser also were fitted with rubber septa. The flask was purged continuously with dry nitrogen (Matheson extra dry grade) which was introduced via a syringe needle inserted through the rubber septum fitted on one of the three necks of the flask; the nitrogen exited via another syringe needle inserted through the condenser-mounted rubber septum. Using a syringe, the flask was charged with 0.5 g (1.56 mmole) of 2-(2-hydroxy-3-t-butyl-5-methylphenyl)-5-chlorobenzotriazole (TINUVIN 326, Ciba-Geigy Corporation, Hawthorne, New York) dissolved in 30 ml of 25 dry tetrahydrofuran (THF) (Gold Label, 99.9 percent, Aldrich Chemical Company, Inc., Milwaukee, Wisconsin). The result- .ing solution was cooled in a dry ice/acetone bath to a temperature of about -78' while being stirred with a magnetic stirrer. To the cold solution was slowly added dropwise 0.48 g of lithium diispropylamine (Aldrich Chemical Company, Inc.) in approximately 5 ml of THF which had been added "ria a syringe to the addition funnel. The resulting mixture was stirred for one hour, after which time 0.91 g (1.56 mmole) of a compound having the following formula (TEGOPREN 3010, Th. Goldschm' It AG, Essen, Federal Republic of Germany), dissolved in about 5 ml of THF, was I 1 *I~-ar~--rrrrrr~: added dropwise by means of the addition funnel (charged by syringe injection), over a 20-minute period:

CH

3

CH

3 I I (CH3)3Si-(-Si-)4-

O

-Si-

O

-Si(CH) 3 I I

CH

3

(CH

2 3

HC

O0

H

2

C/

The resulting mixture was allowed to warm to ambient temperature, with stirring. The mixture was allowed to stir for four hours, after which time the solvent was Sremoved under reduced pressure by means of a rotating evaporator (Buchi Rotovap, Model RE 120). The residue was a pale yellow wax. Infrared analysis of the material showed absorption maxima at 3600 and 3100 cm 1 0 SO0 04 4 Example 2 20 Preparation of Additive D02 The procedure of Example 1 was repeated, except that S9 the 2-(2-hydroxy-3-t-butyl-5-methylphenyl)-5-chlorobenzotriazole was replaced with 10 g (4 mmole) of poly(N-phydroxyethyl-2,26, 6-tetramethyl-4-hydroxypiperidyl succinate) having a molecular weight of approximately 2300 (TINUVIN 622 LD, Ciba-Geigy Corporation, Ardsley, New York), the lithium diisopropylamine was replaced with 0.26 g (4 mmole) of butyl lithium (Aldrich Chemical Company, Inc.), and the amount of TEGOPREN 3010 was increased to 2.4 g (4 mmole). The yield of additive was 9.6 g (77 percent).

B. Polymers The polymers employed are summarized in Table 9 which is based on data supplied by the manufacturers. In the table, the melt flow rate is given in the column labeled -57-

J

bi i' "MFR" and was determined in accordance with ASTM Test Method D1238-82, "Standard Test Method for Flow Rates of Thermoplastics by Extrusion Plastometer." The polydispersity, PD, is the ratio of the weight-average molecular weight, Mw, to the number-average molecular weight, Mn.

Table 9 Summary of Polymers Employed Polymer Temp.

Code MFR PD Mn_ Mw_ Ranqe a PPAb 35 2.7 52,000 140,000 293-316

PPB

c 400 4.0 17,000 68,000 254-304 PPCd 400 4.0 17,000 68,000 254-304 15 PPDe 60 4.0 30,000 NA f

NA

o, PPEg NA NA NA NA 204-260 a. PPFh NA NA NA NA NA S' PEAL NA NA NA NA NA SPEB3 NA NA NA NA NA o 20 PSA NA NA NA NA 2451 aDegrees

C.

bType PC-973 polypropylene, Himont Incorporated, Wilmington, Delaware.

CType PF-441 pclypropylene, Himont Incorporated.

dType PF-015 polypropylene, Himont Incorporated; the polymer is type PF-441 to which has been added 500 ppm of Lubrizol 101 (Lubrizol, Inc., Wickliffe, Ohio).

eType PF-444 polypropylene, Himont Incorporated.

4r fNot available.

S 30 gType 5A08 polypropylene, Shell Chemical Co., Houston, Texas; melt index, 3.0 g/10 min.; and specific gravity, 0.903.

hType WRS-5-144 polypropylene, Shell Chemical Co., Houston, Texas.

iType 61800.06 low density 1yethylene, Dow Chemical Co., Midland, Michigan.

-58- JType 3404 low density polyethylene, Norchem, Inc., Rolling Meadows, Illinois; melt index, 1 g/10 min.; and density, 0.922 g/cm 3 kType PET 7352 poly(ethylene terephthalate), Eastman Chemical Products, Inc., Kingsport, Tennessee; melt index, 1.2 g/10 min.; and specific gravity, 1.4.

1 Recommended melt processing temperature.

II. Preparation of Compositions Surface-segregatable thermoplastic, melt-extrudable compositions as provided by the present invention were prepared by several methods. However, only those methods are described below which permitted isolation of the composition prior to a melt-processing step; a 15 bench-scale method, and a pilot-scale method. The preparai otions of compositions simultaneously with melt-processing .Oq t are described in conjuzntion with such mvlt-processing.

0 0 0 SExamples 3-49 A. Bench-Scale Method o« 4Approximately 10 g of a polymer in pellet form was mixed in a beaker with the desired amount of additive.

The resulting mixture was poured into the hopper of a 25 small compounding unit (Max Mixing Extruder, No. CS-194- FA-093, Custom Scientific Instruments, Inc., New York, New York). The mixture was heated in the extruder of the compounder to a temperature of 180" and extruded through a die having a single, approximately 4-mm diameter, orifice.

The extruded composition was collected either on aluminum foil or in a glass evaporating dish. The cooled material was cut manually into apprqximately 6-mm long pieces.

The compositions prepared are summarized in Table -59- Table Summary of Bench-Scale- Preparations of Cornrositions I *4 0* *44 I~ 4 I Ii 40 I 0 It 04 4* 00 0 0 O 4 ''4 I 1

I'

4 1 I'll 4* II 1 1 Example 3 4 6 7 8 9 11 15 12 13 14 15 16 20 17 3,8 19 20 21 22 23 24 25 26 27 28 29 31 32 33 composition Code PP01-1 PP02-1 PP03-1 PP04-1 PP05-1 PS 01-1 PS02-1 PP06-1.

PP07-1 PE01-1, PE02-21 PS03 -1 PP08-1 T ,09-1 PP10-1 PE03-1 PE04-1 PP11-1 PP12-1 PE 05-1 PE06-1 PP13-1 PP14-1 PE07-1 PE08-1 PP2,5-1 PP16-1 PP17-1 PP18-1 PP1,9-1 PE09-1 Polymer Code

PPA

PPA

PPA

PPA

PPA

PSA

PSA

PPA

PPA

PEA

PEA

PSA

PPA

PPA

PPA

PEA

PEA

PPA

PPA

PEA

PEA

PPA

PPA

PEA

PEA

PPA

PPA

PPA

PPA

PPA

PEA

code (s) A13 A18 A18 A20 A2 0 A20 A20 A21 A21 A21 A21 A2 3 B0 1 BQ 1) B 0, 101, B01 B04 B04 B04 B04 806 B09 BlO CO 1 CO 1 CO 1 Additive (s) Kt. Percent 2 1 3 1 3 2 1 3 1 3 2 1 2 3 1 3 1 3 1 3 40 0 0 4 0 44 00 00 44 *04 00 0 0 04 0 40 404 0 O 44 40 '04 44 04 4, 0 0 '44, 0 44 to 04 44 40 44 *4 4, 44 4 0 4 34 36 37 38 39 41 42 43 44 15 45 20 46 47 25 48 49 PE 10-1 PE 11-1 PE12-1 PE 13-1 PE14-1 PP20-1 PP21-1 PP22-2 PP23-2 PP24-2 PP25-3

PEA

PEA

PEA

PEA

PEA

PPA

PPA

PPA

PPA

PPA

PPA

co1 D01 D01 DO02 D03 D04 D05 B02 Bli B06

BIO

Bll B04 B05 col B04 B05 col B04 505 CO 1 B04 B05 co 1 B04 col B04 col 3 1 3 3 3 3 3 0.33 O0.33 0.33 1 1 1 1.67 1.67 1.67 0.33 0.33 (~.33 1 1 1 1.67 1.67 1.67 PP26-3 PP27-3 PE 15-3

PPA

PPA

PEA

PE 16-3 PE17-3

PEA

PEA

4,4 *044 04 41 o 4 -61- -48j Examples 50-130 B. Pilot-Scale Method To a weighed amount of polymer, typically from about 13 to about 45 kg, in a plastic-lined fiber drum was added the desired amount of additive. The components then were mixed mechanically in a paddle mixer (Banbury, Ann Arbor, Michigan). The hopper of a twin-screw compounding unit (Egan Machinery Company, Sommerville, New Jersey) was charged with the resulting mixture. The mixture was gravity-fed to the compounding screws. Compounding was accomplished at a temperature of from about 180 to about 250', depending on the polymer employed. The resulting composition was extruded though a die having six orifices with diameters of about 3 mm. The extruded filaments were passed through a ten-foot water bath and then a forced-air blower. The dried filaments were pelletized in a rotary pelletizer (Cumberland Company, New York, New York) and stored in 23-kg lots in plastic-lined boxes.

20 The resulting compositions are summarized in Table 11. In some cases, an elemental analysis was carried out on the composition by Galbraith Laboratories, Inc., Knoxville, Tennessee. The results of the elemental analyses are summarized in Table 12, t0 Table 11 Summary of Pilot-Scale Preparations of Compositions Composition Polymer Additive(s) Example Code code Code(s) Wt. Percent PP28-1 PPA A21 1 51 PP29-1 PPA A21 3 52 PP30-1 PPA A21 53 PP31-1 PPA A21 12 54 PE18-1 PEA A21 1 PE19-1 PEA A21 3 -62- 56 PE20-1 PEA A21 57 PP32-1 PPA BOl 3 58 PP33-1 PPA B01 59 PP34-1 PPB B01 3 60 PP35-1 PPB B0, 61 PP36-1 PPC B01 3 62 PP37-1 PPC B01 63 PE21-. PEA DO). 3 64 PE22-1 PEA B01 65 PP38-1 PPA B02 3 66 PP39-1 PPA B02 67 PP40-1 PPC B02 3 68 PP41-1 PPC B02 69 PP42-1. PPA BO3 3 70 PP43-1 PPA B03 71 PP44-1 PB03 14172 PP45-1 PPC B03 73 PP46-1 PPA 1304 3 74 PP47-1 PPA B04 75 PE23-1 PEA B04 3 )76 PE24-1 PEA B04 77 PP48-1 PPA B05 3 78 PP49-1 PPA DO5 79 PRJ25-1, PEA B05 3 80 PE26-1 PEA DO5 81, P P 5 PPA B06 3 82 PP51-1 PPA B06 a83 PP52-2. PPC B06 3 84 PP53-1 PPC B06 85 PP54-1 PPA B07 3 86 PP55-1 PPA B075 87 PP56-1 PPC B07 3 88 I P5 7 -1 PPC B07 89 PP58-1 PPA B08 3 90 PP59-1. PPA B08 91 PP60-1 PPC B08 3 -63- 93 94 96 97 98 99 100 16 101 102 1,03 104 105 is5 106 107 108 109 110 20 ill 112 113 ,14 115 00 0 0~ I II #0 00 0 000 00 0 0 01 0 00 00 0 0 00 0 00 QO 00 p0 0 0 0 PP61-1 PP62-1 PP63-1 PP64-1 PP65-1 PP66-1 PP67-1 EIP68-1 PP69-1 PP7 0-1 PP71-1 PP72-1 PP7 3-1 PP74-1 PP75 -1 PP76-1 PP77-1 PE27-.

PE28-1 PE29-1 PP78-1 PP7 9-1 PP80-, PP8 1-2 PP82-2 PP83-2 PP84 -2 PP85-2 PP86-2

PPC

PPA

PPA

PPA

PPC

PPc

PPA

PPA

PPc PPc

PPA

PPA

PPC

PPc

PPA

PPA

PPA

PEA

PEA

PE~A

PPA

PPA

PPA

PPA

PPA

PPA

PPA

PPA

PPA

B08 B09 B09 B09 B09 B09 B10 BlO B10 B10 Bl Bli 811 Bl c 01 col COl COl Co 1 COl DO03 D04

DOS

B02 8311 802 811 BO6

BOG

810 BI 0 82,1 8310 81.1 2 3 3 3 3 3 3 1 3 3 3 3 1~ 0~ 0 0 00 2 30 116 fi7 118 119 120 -64- 4# 4 4 44 4 44 4' 4 4 444 44 4 4 44 4 #4 44 I 4 #4 1 44 121 122 123 124 125 15 126 127 128 129 130 PP87-3 PP88-3 PP89-3 PP90-3 PP91-3

PPA

PPA

PPA

PPA

PPA

B06 B09 B06 B09 Eli B09 BlO Eli B04 Col B04 col B04 col B04 col,.

B04 Col B04 Col B04 E0S Col 1.6 0.67 0.67 0.67 0.33 0.33 0.67 1 1 1 1.67 1.67 1.67 PP92-3 PP93-3

PPA

PPA

PE30-3 PE31-3 PE 32-3

PEA

PEA

PEA

i Table 12 Elemental Analyses of Selected Compositions Example 52 74 78 81 93 98 102 15 108 112 121 122 123 124 126 Composition Code PP28-1 PP30-1 PP38-1 PP47-1 PP49-1 PP50-1 PP62-1 PP67-1 PP71-1 PP77-1 PP78-1 PP87-3 PP88-3 PP89-3 PP91-3 PP92-3 c 85.60 84.28 84.36 84.44 84.51 84.90 83.56 84.49 83.86 84.05 83.83 84.30 82.70 84,36 85.04 85.11

%H

13.96 13.54 13.83 13.50 13.47 13.79 13.39 13.65 13.55 13.58 13.49 13.70 13.50 13.74 13.58 13.59 Si 0.23 0.77 0.50 0.47 0.36 0.77 0.42 0.47 0.42 0.38 1.06 0.45 0.64 0.33 0.27 0.52 Elemental Analysis 4 t 0 t' 00 4 .4 4 0 I 04 00 0 0.93 It is evident from the data in Table composition analyzed contained additive.

effectiveness of the additive remained to be C. Hot-Stage Microscope Study 12 that each However, the demonstrated.

A hot-stage microscope study was conducted on several polymer-additive combinations in an effort to gain an insight into the compatibility aspect of the additive with the polymer. Although the study actually was done later in the program, it is reported here for convenience, except for one part which will be described in Section VI.

Briefly, polymer, either in the form of small granules or fibers, both with and without additives, was observed under a hot-stage microscope at two temperatures, 160* and 220°, at a magnification of 350x. The equipment consisted -66- [1 of a Mettler hot-stage and a Zeiss Universal optical microscope equipped with transmitted light optics. The presence of additive globules at either temperature was an indication of the incompatibility of the additive with the polymer at the temperature of observation. The study was conducted by Ricerca, Inc., Painesville, Ohio.

The first material studied was the web of Example 327 which was prepared from a composition of the present invention consisting of polymer PPA and 3 percent by weight of additive All. Figure 2A is a representation of the photomicrograph at 160° and Figure 2B is a representation of the photomicrograph at 2200. In Figure 2A, additive globules 21 clearly are present. Also present are what o appear to be a few particles 22 of debris or foreign Sa 15 matter. At 220°, as seen in Figure 2B, a few additive t °o globules 21 seem to be present, but they appear to be slightly smaller in size. Again, some debris particles 22 S are present.

lo The existence of a large number of additive globules c 20 at 160° demonstrates that the additive is incompatible with the polymer at that temperature. Moreover, the fact t, that the number of globules decreases significantly at 220* indicates that additive compatibility with the polymer has increased substantially. Since melt-extrusion tempera- 25 tures for polymer PPA typically are in the range of from about 250 to about 300', the additive clearly will be .compatible with the polymer at melt extrusion temperatures.

The second material consisted of polymer PPA alone as a negative control. Figures 3A and 3B are representations of the hot-stage photomicrographs at 160 and 220", respectively. In Figure 3A, crystallites 31 are seen. While not apparent from the Figures, such crystallites 31 differ in appearance and are distinguishable from additive globules, such as additive globules 21 in Figure 2A. Upon heating to 220°, as shown by Figure 3B, most of the orystallites 31 have disappeared; some debris 32 is present.

-67- As a positive control, composition PP21-1 from Exsimple was studied under the same conditions. Representations of the photomicrographs are shown as Figures 4A and 4B.

In both figures, numerous globules 41 of additive D05 are apparent. Some of such globules apparently have coalesced at the higher temperature to form droplets 43 (Figure 4B).

At least one debris particle 42 is seen in Figure 4A.

The incompatibility of additive D05 in polymer PPA at both 160 and 220° is striking, especially when Figure 4B is compared with Figure 2B. Moreover, it is clear that the additive becomes less compatible with the polymer as the temperature of the polymer increases.

This discussion of the hot-stage microscope study concludes with the results obtained with composition PP26- 3 from Example 45. That composition, it will be recalled, S'S consists of polymer PPA and a mixture of additives having molecular weights of 3,000, 3,000, and 8,000, respectively.

The presence of additive globules 51 is seen in Figure which represents the hot-stage photomicrograph at 160°.

20 Such globules appear to be nearly gone at 220° (Figure Thus, Figures 5A and 5B are similar to Figures 2A and 2B, respectively, and demonstrate that the additive mixture changes from incompatible to compatible as the temperature of the polymer is raised from 160 to 220°.

Several other compositions of the present invention were included in the hot-stage microscope study with results similar to those shown in Figures 2A, 2B, 5A, and From the foregoing, it is apparent that the use of the It 30 hot-stage microscope as just described can be used as a simple method for determining whether or not any given additive or additive mixture is likely to segregate in a controlled manner to the surface of a fiber or film as described herein. If the additive or additive mixture forms globules which remain at both 160 and 220°, the probability is that such additive or additive mixture -68will not segregate to one or more of the interfacial surface, effective surface, and subsurface. In addition, the melt-processing of a composition incorporating therein such additive or additive mixture probably will not be successful. On the other hand, if the additive or additive mixture does not form globules at 160°, the additive or additive mixture is compatible with the polymer at temperatures below melt-extrusion temperatures and probably will remain distributed throughout the bulk of the resulting fiber or film without any controlled segregation toward the surface.

III. Preparation of Melt-Pressed Films Examples 131-176 4,s As an initial screening method, films were pressed from various of the compositions prepared and described in *4 -ection II, above. The apparatus employed was a Carver 0o 4: Laboratory Press, Model 2518 (Fred S. Carver, Inc., Meno- 20 monee Falls, Wisconsin) having heated plates. From about 1 to about 10 g of a composition was placed between two sheets of aluminum foil and the resulting assembly was placed on the bottom plate of the press, the plates having been preheated to about 180'. Pressure up to about 10,000 4 I4 psig was applied and maintained for no more than about seconds. The pressure was released and the foil sandwich was removed from the press. The foil was removed and the film thus obtained was stored in a plastic bag. Film thicknesses of from about 1 to about 5 microns typically ,0 30 were obtained. The wettability of each film made with a type A, B, or C additive was qualitatively estimated by simply placing a drop of water, on the surface and observing whether or not the drop wet the surface of the film. The films obtained and the results of the wettability screen are summarized in Table 13.

-69- L1 i I Table 13 Summary of Melt-Pressed Films Pretpared from Compositions Prepared in Section II 90 0 0 90 o 00 99 9 0 909 99 9 9 999 9 90 99 0 9 94 9 99 99 90 9 0 0 0 Exampl1e 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 composition- Example Code 3 ppo1-1 4 PP02-1 5 PP03-1 6 PP04-1 7 PP05-1 8 P801-1 9 PS02-1 10 PP06-1 11 PP07-1 12 PE01-1 13 PE02-1 14 PS63-1 15 PP08-1 16 PP09-1 17 PP1o-1 18 PE03-1 19 PE04-1 20 pp11-1 21 PP12-1 22 PE05-1 23 PE06-1 24 PP13-1.

25 PP14-1 26 PE07-1 27 PEO8-1 28 PP15-1 29 PP16-1 PP3.7-1 31 tP1-1 32 PP19-1 Wettabil ity Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive P0 sit ive Positi~ve Positive Positive Positive Positive Positive Positive Positive positive Positi-va Pos itive Positive Pos itive Positive 9999 9 9 9 .9 9 4 0.0 0 0 9 00 99 94 99 0 0 9 O 0 0 9 9 0-990 09 ~9 9 0 0 l~g~D~l ia31*I~~'- i-i- 161 33 162 34 163 35 164 36 165 37 166 38 167 39 168 40 169 41 170 42 171 43 172 44 173 45 174 46 175 47 176 48 177 49 aNot applicable, to impart water PE09-1 Positive PE10-1 Positive PE11-1 N/Aa PE12-1 N/A PE13-1 N/A PE14-1 N/A PP20-1 N/A PP21-1 N/A PP22-2 Positive PP23-2 Positive PP24-2 Positive PP25-3 Positive PP26-3 Positive PP27-3 Positive PE15-3 Positive PE16-3 Positive PE17-3 Positive since the additive was not designed wettability.

(4 4 .4 4r 4 4e 4 4 4 4 44 6 4r #6 4 4 0444 0, 444* o 44 04 44 4 o In an effort to obtain some indication of the preferential segregation of additive(s) to the surface of the melt-pressed films, a sample of the film of Example 173 was subjected to scanning electron microscopy in conjunction with a silicon x-ray probe (Si-SEM) in accordance with standard procedures. The scanning electron microscope was .manufactured by Cambridge Instruments, Cambridge, England, and the x-ray probe was manufactured by Princeton Gamma Tech, Princeton, California.

30 The sample of the film of Example 173 is represented diagrammatically by Figure 6, in which film sample 60 has top surface 61 and front end surface 62. Figure 7 is the diagrammatic representation of Figure 6 on which has been superimposed the results of the Si-SEM. In Figure 7, film sample 70 has top surface 71 and front end surface 72.

Each of dots 73 represents the presence of silicon atoms.

-71-

L;

It is clear that the additives included in the composition from which the film of Example 173 was prepared have segregated preferentially to the surface region of the film. The absenca of silicon in the core region of the film is striking, The irregular distribution of silicon along top surface 71 (Figure 7) is believed to have resulted from the irregularities present in the surface of the top plate of the press. Such irregularities include the generally streaked orientation of silicon atoms along surface 71.

Water contact angles were measured for several of the melt-pressed films. The apparatus employed was an NRL Goniometer, Model No. 100-00-115 (Rame-Hart, Inc., Mountain Lakes, New Jersey. The water used was HPLC Grade water (Fisher Scientific, Pittsburgh, Pennsylvania) The results of the measurements are summarized in Table 14.

i Table 14 Water Contact Angles for Selected S*J 20 Melt-Pressed Films Film Example Contact Angle, 131 <2 144 <2 156 157 12 158 171 7 Controla 98 167 105 168b 115 aFilm pressed from virgin polymer (PPA) without any additive.

bFilm pressed from the composition consisting of polymer PPA and additive D05 as a positive control.

-72- The presence of either an additive intended to impart water wettability or an additive intended to increase the surface energy of the film clearly changed the contact angle measurement of the film relative to the control film which did not contain additive. Additives of the former type decreased the contact angle, as expected, and the additive of the latter type increased the contact angle, also as expected.

With respect to the two films which contained an additive which absorbed ultraviolet radiation, the.

films of Examples 163 and 164, they showed a broad, strong absorption band from 220 to 360 nm when analyzed on a ultraviolet spectrophotometer.

Samples of both films were subjected to electron 15 spectroscopy for chemical analysis (ESCA). The ESCA data were collected by Surface Science Laboratories, Inc Mountain View, California, using a Hewlett-Packard 5950 B .spectrometer with a monochromatic aluminum K-alpha x-ray source. The scans were dor.n with the open aperture setting 20 for high sensitivity (low resolution), The x-ray power setting was 600-800 watts and charge neutralization was accomplished with a flood gun setting of 13 electron volts. The vacuum utilized was l0 8 Torr. The area analyzed was about 1 x 4 mm and the sampling depth was about 100 A.

In addition, each film was subjected to bulk elemental ,.analysis. The ESCA data and the results of the elemental analyses are summarized in Table r t i ts n -73- L L -i 44 4 4 4 Table Summary of ESCA Data and Elemental Analyses on Melt-Pressed Films Containing a UV Absorber ESCA Data Bulk Elemental Analyses Example %C %O N Si %C H N %Si 163 64 12 12 6 85.30 14.10 0.13 0.26 164 631 11 14 7 85.10 14.37 0.10 0.33 Because ESCA analyses are limited to a depth of about 100 A, two film samples were submitted for analysis by Rutherford back scattering (RBS) spectrometry. The analyses were carried out by Charles Evans Associates, Redwood City, California. The apparatus employed was a General Ionics Model 4110 Tandem Accelerator (General Ionics Corporation, Newburyport, Massachusetts) using an Evans End Station (Charles Evans Associates). A 2.275 MeV He ion probe was used, with a detection angle of 160 degrees. Typical beam currents were 1-20 nanoamps. Ions were detected by surface barrier detectors. Data analysis involved the TOS source code written by Charles Evans Associates and owned by General Ionics Corporation. The energy losses of the scattered helium nuclei give information on the nature and depth of the target atoms in the polymer matrix. The results are summarized in Table 16.

Table 16 Summary of RBS Analyses on Melt-Pressed Films Atomic Concentration.,Atom t Exam]!1 __nth o A s Ti 144 0-500 30 0.3 0.09 ,6.01 a >500 30 0.1 0,03 <0.O1a -74j ,i ij^n.Tlliiiii-uT.. r n m^ A, it,. 4.

1 173 0-500 30 1.0 0.56 <0.01 a 500-1000 30 0.6 0.15 <0.O01 a >1000 30 0.1 0.04 <O.Ola aThis concentration was at or near the detection limit; the actual concentration may be considerably lower.

The RBS data from Table 16 for the film of Example 173 were plotted as the atomic concentration of silicon in atom percent (y-axis) versus depth in A (n-axis); the plot is shown as Figure 8. In this and all subsequent plots of RBS data, the silicon concentrations were drawn parallel to the x-axis as lines which correspond to the depth field and the midpoints of such lines then were connected to obtain the curve shown in the plot, It is evident from Figure 8 that most of the additives have segregated to the interfacial surface, effective surface, and subsurface of the film. Below a depth of around 1000- 1250 A, the concentration of silicon is very low, i.e., 0 20 no more than about 0.04 atom percent.

The films from Examples 144 and 173 also were submitted for ESCA and bulk elemental analyses. The results ot these analyses are shown in Table 17.

Table 17, Summary of ESCA Data and Elemental Analyses for the Films of Examples 144 and 172 ESCA Data Bulk Elemental Anal.

Example j_ Q i _LJ ,,9 144 94 4.4 1.3 84.21 13.32 0.24 173 62 25 12 85.11 13.59 0.52 It is apparent that the ESCA data and the RBS data cannot be correlated, partly because of the differences in the depths of measurements and partly because of the i i i nonlinear concentration gradient whit.. exists from the interfacial surface to the core of the film. Taken together, however, the data clearly establish the controlled segregation of additive toward the surface of the film.

The evaluation of the film from Example 165 which contained additive D02 consisted of an accelerated ultraviolet radiation exposure trial. A sample of film measuring 3.8 x 10 cm, along with a control film pressed from virgin polymer, was suspended 0.91 m in front of a 400-watt mercury arc lamp (Hanovia 674A10). Both films were exposed continuously for 12 hours. The films then were moved to a distance of 0.30 m from the lamps and exposed continuously for an additional 8 hours. Upon examining both films, it was found that the film of Example 165 appeared to be unchanged, whereas the control film was brittle and could not be bent without breaking.

Before evaluating the film of Example 166 which contained buffering additive 003, the additive itself was examined for its buffering capabilities. This was done by SP,, 20 charging a 50-ml beaker with 15 ml of deionized water and a small magnetic stirring bar. The beaker was placed on top of a magnetic stirrer and fitted with a calibrated pH electrode. The beaker then was charged with 0Q032 g (1 drop) of TRITON X-102 (Rohm and Haas Co., Philad&lj 1 ha, Pennsylvania) and the pH of the resulting solution measured.

o, To the solution in the beaker then was added 0.032 g (1 *drop) of additive D03, followed by the measurement of the solution pH. Three additional, equal amounts of additive *oo D03 were added sequentially, with the solution pH being 30 measured after each addition. The results are presented in Table 18.

-76- Table 18 Summary of pH Measurements of Aqueous Additive D03 Solutions Solution Composition Water and 1 drop TRITON Water, 1 drop TRITON, 1 drop D03 Water, 1 drop TRITON, 2 drops D03 Water, 1 drop TRITON, 3 drops D03 Solution pH 5.50 6.25 8.30 8.72 4 4 4 14 t 4 I* 4 It The solution containing 1 drop of TRITON X-102 and 3 drops of additive D03 (0.096 g) then was titrated with 0.01 N hydrochloric acid. That is, incremental volumes of hydrochloric acid were added, with the pH of the solution being measured after each addition. The results are summarized in Table 19, which shows the cumulative volume of acid added.

Table 19 20 Titration of Additive D03 Solution Volume (ml HC1 Added 0.2 Solution PH 8.72 6.55 6.91 6.73 6.74 6.70 6.62 It is clear that additive D03 is capable of acting as a buffer. The sharp drop in pH with the first addition of acid was expected, since a buffer system consists of a weak acid or base and its salt; consequently, buffering behavior could not be seen until acid had been added to form the salt of additive D03.

-77i Having verified the buffering capability of additive D03, the procedure which provided the data for Tble 19 was repeated, except that the three aliquots of additive D03 were replaced with a sample of the film of Example 166 weighing 0.211 g and only three 0.5-ml additions of hydrochloric acid were done. The results are summarized in Table 20; again, the cumulative volume of acid is shown.

Table Titration of 0.21i-a Samnle of Film 166 Volume (ml) HC1 Added None (sample absent) None (sample present) 0.5 1.0 1.5 Solution pH 5.71 5.91 5.90 5.90 5.75 t i t 4, *4 4 4 S 44 4 4 I *4 The titration of a sample of the film of Example 166 20 was repeated, except that the film sample weighed 0.474 g.

The results are shown in Table 21 which shows the cumulative volume of acid added.

Table 21 Titration of 0.474-q Sample of Film 166 Volume (ml) HC1 Added None (sample absent) None (sample present) Solution PH 5.60 6.70 6.69 6.69 6.69 6.60 6.40 4.60 -78- :1 Additive D03 not only retains its buffering capability when incorporated into a composition from which a film is formed, but also clearly is on the interfacial surface; otherwise, the additive could not buffer the solution in which the film was placed since the solution could not swell the film under the conditions of the test.

While the additives clearly segregated to the surfaces of the melt-pressed films and in general were effective in imparting to the film surfaces the desired characteristics, the critical test remained to be conducted; namely, the preparation of melt-processed fibers or films to determine whether or not additive segregation will occur under the conditions encountered during fiber and continuous film formation. Thus, the preparation of fibers is the subject of the next section.

IV. Preparation of Fibers 0 S' Exambles 178-239 20 A. Meltblown Fibers from Bench-Scale Apparatus As a simple screening method, fibers were formed by means of a bench-scale apparatus having a single orifice in the die tip. The apparatus consisted of a cylindrical steel reservoir having a capacity of about 15 g. The reservoir was enclosed b' an electrically heated steel jacket. The temperature if the reservoir was thermostatically controlled by means of a feedback thermocouple mounted in the body of the reservoir. The extrusion orifice had a diameter of 0.016 inch (0.41 mm) and a length of 0.060 inch (1.5 mm). A second thermocouple was mounted near the die tip. The exterior surface of the die tip was flush with the reservoir body. Composition extrusion was accomplished by means of a compressed air piston in the reservoir. The extruded filament was surrounded and attenuated by a cylindrical air stream exiting a circular 0.075-inch (1.9-mm) gap. Attenuating air pressures typical- -79- L_ .j ly were of the order of 5-90 psig. The forming distance was approximately 10 inches (25 cm). The attenuated extruded filament was collected on the clear plastic film of an 8.5 x 11 inch (21.6 x 27.9 cm) loose leaf protector having a black paper insert.

In each case, the material extruded consisted of a simple mixture of a polymer and the desired additive(s) in the desired amount(s). The mixtures extruded (seltblown) are summarized in Table 22.

Table 22 Summary of Compositions Meltblown on Bench-Scale Apparatus 15 Polymer Additive o Example Code Code Wt. Percent S178 PPA A01 3 179 PPC A01 3 180 PPA A02 3 20 181 PPC A02 3 132 PFA A03 3 183 PPC A03 3 184 PPA A04 3 185 PPC A04 3 186 PPA A05 3 187 PPC A05 3 188 PPA A06 3 189 PPC A06 3 190 PPA A07 3 191 PPC A07 3 192 PPA A08 3 193 PPC A08 3 194 PPA A09 3 195 PPC A09 3 196 PPA A10 2 197 PPA A10 3 to 22O*, as shown by Figure 3B, most of the crystallites 31 have disappeared; some debris 32 is present.

-67-

L

198 PPC A10 3 199 PPA All 3 200 PPA All 201 PPB All 3 202 PIPB All 203 PPA A12 3 204 PPC A12; 3 205 PPA A13 2 206 PPA A13 3 207 PPC A13 3 208 PPA A14 3 209 PPC A14 3 210 PPA A15 2 211 PPA A15 3 212 PPC A15 3 213 PPA A16 3 214 PPC A16 3 21 P 1 215 PPA A17 2 2 16 PPC A17 3 *:219 PPA A183 20217 PPA A19B 221 PPC A19 3 222 PPA A20 2 223 EPA A20 3 224 PPB A20 3 225 EEC A20 3 226 EPA A22 3 227 EEC A22 3 228 EPA A24 2 229 PPA A24 3 230 PPB A24 3 231 EEC A24 3 232 PPA BOl 2 233 EPA B02 2 -81forms globules which remain at both 160 and 220°, the probability is that such additive or additive mixture -68i i i i 234 235 236 237

PPA

PPA

PPA

PPA

B03 B04 B11 B04 C01 B04 C01 B04 C01 2 2 2 0.33 0.33 0.33 0.67 0.67 0.67 1 1 1 238 PPA PPA 239 I t 0r t 4 0- I t 4r tot 1 4Z 4 to6 o ot 4 6 4144 44 4 Meltblowing conditions for any given composition depended primarily on the polymer component. Consequently, standardized conditions were utilized for each of the three polymers as summarized in Table 23.

Table 23 20 Summary of Meltblowing Conditions Using the Bench-Scale Apparatus

A

Polymer Die Air Code Temp.. Temp., PPA 260 228 PPB 249 249 PPC 240 230 aThe conditions given are approximate only and typically may vary by as 30 much as 301.

The wettability of each web was estimated by placing a drop of water on a sample of the nonwoven material and measuring the time required for complete penetration of the water drop into the fabric (referred to hereinafter as "wetting time"). Each sample was tested with a minimum of -82- 1 five drops of water placed in five different locations.

If all of the drops wet the web within three seconds, the web was considered to be immediately wettable wettable). If the wetting times of the drops were greater than three seconds and equal to or less than 30 seconds, the web was considered to be slowly wettable. If wetting times were greater than 30 seconds, the web was considered to be nonwettable.

Of the webs obtained in Examples 178-239, inclusive, those from Examples 178-227, 232-234, and 237-239, inclusive, were immediately wettable, although in some cases wettability was dependent upon fiber diameter. Those from Examples 228-231, inclusive, 235, and 236 were nonwettable.

It is seen from Table 16 that Examples 228-231 employed 4 15 additive A24, Example 235 employed additive B04, and Example 236 employed additive Bll. According to Table 1i, *additive A24 has a molecular weight of about 7,900. From Table 3, it is seen that additive B04 has a molecular 4 4 weight of about 3,000 and additive B11 has a molecular 20 weight of about 15,000. All three molecular weights are high enough to prevent the rapid segregation of the additive to the effective and/or interfacial surface region of the fibers. Consequently, the fibers were not wettable.

It should be noted, however, that webs made from composition containing a mixture of additives having molecular weights equal to or greater than about 3,000, the webs of Examples 237-239, inclusive, were wettable, while webs made from a composition containing any

L

one of the additives used in the mixture were not wettable i 30 the web of Example 235). This illustrates the apparent synergistic effect which can result from combining additives, even though such additives individually do not segregate under similar melt-processing conditions above the subsurface of the fibers or films.

-83- 1 Some qualitative observations on web quality and wettability as a function of fiber diameter are appropriate at this point, at least for webs made with polymer PPA.

Web quality was based on visual inspection or inspection under a low-power optical microscope and was rated on a scale of from 1 to 4 as follows: 4 fibers having uniform diameters with no shot present; 3 fibers having a small amount of fiber diameter nonuniformity, with small amounts of shot present (fiber diameter nonuniformity refers to variations of fiber diameter, the presence of varying large and small fiber diameters); 2 moderate fiber nonuniformity and a moderate amount of shot present; and 1 I substantial fiber nonuniformity and a large amount of shot present.

4 4' Fiber diameters also were estimated visually or under V as 0 the microscope and were simply classed as small, medium, 20 or large. As will be described in greater detail later, 0 A fiber diameter is a function of attenuating air pressurethe higher the pressure, the smaller the fiber diameters.

A number of the webs obtained in Examples 178-239, inclusive, were evaluated for web quality and fiber diameter. The results of this evaluation and tha wettabilities a an of the webs evaluated are summarized in Table 24.

Table 24 t, r Summary of Evaluations of Web Quality and iber Diameters Additive Cloud Primary Web Code MW Pointa Airb Rating Wettabilityc A06 678 2 25-90 4 WS, WM, WL All 852 3 25-90 4 WS, WM, WL A13 852 2 25-90 4 WS, WM, WL -84superimposed the results of the Si-SEM; In Figure 7, film sample 70 has top surface 71 and front end surface 72.

Each of dots 73 represents the presence of silicon atoms.

-71r I k-r

S.

4 0r 0 0 4 4 44t 4 II 4I 44g 1( *4 4 4 0I 4440 4 4r *e r Z r A17 1130 45 27 1 WL A19 1200 40 30 1 WL 1450 0 26-90 4 WS, WM, WL A22 Ad 4 25-85 4 WS, WM, WL A23 NA 4 25-90 4 WS, WM, WL B01 600 10 30-90 4 WS, WM, WL B04 3000 0 30-80 4 WL 3000 le 25 1 Nonwettable f B07 5792 10 25-45 3 WL B08 5962 65 25 1 Slowly Wett.

f Bil 15,444 42 25 1 Nonwettable f C01 8000 42 25 2 Nonwettable f aIn degrees

C.

bin psig.

15 %Code: WS small diameter fibers wettable; WM medium diameter fibers wettable; and WL large diameter fibers wettable.

dNot available.

eInsoluble.

20 fOnly large fibers were produced.

The data in Table 24 substantiate the already-observed decrease in wettability associated with increasing additive molecular weight. In addition, however, the data suggest 25 that there is a correlation between web quality and additive cloud point. That is, when the cloud point of the additive is above about 20' C, web quality declines significantly.

Thus, the cloud point of additives employed to impart water wettability to the surface of fibers or films preferably will be no more than about 20° C and most preferably no more than about 10° C.

Examples 240-261 In order to more fully understand the segregation phenomenon, three series of the bench-scale meltblowing

K"V

experiments were repeated under somewhat more carefully controlled conditions. The first series employed either polymer PPA or PPB and additive levels of two percent by weight; the process and product details are summarized in Tcble 25. Fiber diameters were estimated from scanning electron photomicrographs taken by Surface Science Laboratories,, Inc., Mountain View, California. The instrument employed was a Camscan Series 4 Scanning Electron Microscope. The accelerating voltage was 24 keV, the working distance was 20 mm, and the spot size was 5. The instrument was calibrated with 0.76-micron diameter National Bureau of Standards latex spheres. Each sample was gold coated (100-A thickness) to increase conductivity under the electron beam.

44 II 4 4 4r *o 4 *4 4 4. I 4 4 4oar3 Table Summary of First Series of Additional Bench-Scale Meltblowing Experiments Examplea 240 241 242 243 244 245 246 247 248 249 250 d Additive Code MW B01 600 B01 600 B02 836 B02 836 B03 150 B03 1350 A13 852 A13 852 B04 3000 B04 3000 B04 3000 3000 C01 8000 Air Press, b 40 80 20 80 40 80 35 80 25 40 12 Fiber Dia.c 3 12 3 12 4 12 4 12 -86- -1 i- _i F 'rd I i i I- L IIIIC 2 5 1 d B04 3000 20 6 3000 C01 8000 252 d B04 3000 25 B05 3000 C01 8000 253 d B04 3000 40 2-3 3000 C01 8000 apolymer PPA was employed in every case, except for Examples 250-253, inclusive, which utilized polymer

PPB.

bin psig.

CIn micrometers.

15 dThe polymer contained a mixture of all three additives in equal concentrations; the total of all three additives still was two percent by weight.

In each case, a coherent web was obtained. Each web 20 was subjected to ESCA analysis. Additionally, each web was subjected to bulk elemental analysis and the water drop test. The ESCA data and the results of the elemental analyses and water drop tests are summarized in Table 26.

.4 4 4 4 4 4r 4 6 4 4 44 0 ,e *4 4 Table 26 Summary of Analytical Data And Water Drop Test for Webs from Experiments 240-253, Inclusive t Example 240 241 242 243 244 245 Additive

MW

600 600 836 836 850 850 Fiber Dia.a 15 3 12 3 12 4

ESCA

sib 1.8 2.0 1.9 1.5 2.6 1.7 Bulk Sic 0.006 0.007 0.017 0.018 0.008 0.009 Wettabilitv Wettable Wettable Wettable Wettable Wettable Wettable -87- L 1 a 44 4 44 #4 1 4 4 49 4 P O 4 4 4 WI 4 I 4t 246 852 12 4.3 0.011 Wettable 247 852 4 4.5 0.011 Wettable 248 3000 12 13.0 0.017 Nonwettable 249 3000 5 6.3 0.016 Nonwettable 250 3-8 X 103d 20 8.5 0.010 Wettable 251 3-8 x i q d 6 5.8 0.010 Slowly Wett.

252 3-8 x 103d 5 5.9 0.010 Slowly Wett.

253 3-8 x 1 0 3d 2-3 4.8 0.010 Slowly Wett.

amn micrometers.

bAverage concentration in atom-percent to a depth of approximately 100 A.

CAverage concentration in atom-percent throughout the bulk of the fibers.

dThe polymer contained three additives having molecular weights of 3,000, 3,000, and 8,000, respectively.

From Table 26, it is seen that only two webs were not wettable; both webs were made with additive P 4 which has a molecular weight of about 3,000, Interestingly, the fibers of both webs had higher bulk silicon concentrations and higher surface silicon concentrations than any of the webs which were wettable. Indeed, the fibers of the web from Example 248 had from three to nine times as much silicon in the top 100-A layer of the surface as the fibers of webs which were wettable. Notwithstanding such high concentrations, it is evident that there was insufficient additive in the effective surface to render the webs wettable. Thus, while the higher molecular weight additives will segregate to some extent, additive molecular weights 30 of less than about 3,000 are required in order for additive to migrate to the in',erfacial surface or effective surface in concentrations sufficient to impart wettability to the fibers, at least for fibers having diameters in the 3-15 micrometer range.

In order to demonstrate the effect of fiber diameter on surface silicon concentration, a second series of -88- 1Li' i _Li bench-scale meltblowing experiments was carried out. In this series, the polymer was PPB and the additive was at a level of two percent by weight (the additive molecular weight is 794 see Table ESCA analyses were carried out on the webs, all of which were wettable. The results are summarized in Table 27.

Table 27 Summary of Second Series of Additional Bench-Scale Meltblowing Experiments Air Fiber ESCA Datac Example Press.a Dia.b %C 254 40 6 84 4.7 255 50 4 87 4.1 a 256 60 2 88 3.9 In psig.

bin micrometers, estimated from scanning electron 6 photomicrographs as already described.

20 cAverage concentration in atom-percent to a depth of approximately 100 A; the bulk silicon concentration as determined by elemental analysis was 0.01 atom-percent.

4 4 4 25 From the discussion earlier regarding the factors Sinfluencing the segregation of the additive, it is apparent .that there are two competing factors in the segregation of additive during fiber formation. First, as the diameter of the fiber is diminished, the distance to the surface 30 also is diminished, thereby contributing to higher additive S' concentrations in the surface region. Second, as the diameter of the fiber is diminished, the time the fiber remains in a molten state also is diminished, thereby shortening the time during which the additive can migrate toward the surface. From the data in Table 27, it is evident that the second factor was controlling since -89the additive concentration was reduced as the fiber diameter decreased.

As already pointed out, the higher molecular weight additives segregate toward the surface of the fiber or film, but typically do not reach either the interfacial surface or the effective surface. In cases where the additive has segregated to the subsurface and is sufficiently close to the effective surface, the additive can be "coaxed" to the effective surface by the application of relatively mild heating conditions. This phenoirnon is illustrated by a third series of bench-scale meltblowing experiments.

The third series of experiments involved the incorporation of two weight percent of an additive in PPA polymer 15 essentially as described in Examples 178-239, inclusive.

it S* An ESCA and elemental analysis was obtained for each web.

I' The wettability of each web also was estimated by the water drop test. A sample of each web then was heated in S an oven at 120 degrees for 20 seconds. An ESCA analysis S* 20 was obtained on the heated web and its wettability estimated as before. The results are summarized in Tables 28 and 29.

Table 28 Summary of Third Series of Additional 25 Bench-Scale Meltblowinq Experiments SAdditive Bulk ale code MW sia 257 A15 1023 0.005 258 A18 1200 0.014 259 A20 1450 0.014 260 A23 NAb 0.008 261 BiI 15,444 0.006 aAverage concentration in atom-percent throughout the bulk of the fibers.

bNot available.

form the salt of additive D03.

-77i -i ii Table 29 Summary of ESCA Data and Wettabilicv Testing for Third Series of Bench-Scale Meltblowinq Experiments 7efore and After Heatinc the Webs i Il S I.r

FII

S s a

I(

Ea a a

S

Before Heating After Heating Example ia Wettabil'it Si a Wettability 257 3.2 Nonwettable 5.8 Slowly Wett.

258 1.9 Nonwettable 2.7 Wettable 259 6.9 Wettable 7.4 Wettable 260 4.3 Nonwettable 3.3 Nonwettable 261 4.7 Nonwettable 5.3 Nonwettable aAverage concentration in atom-percent to a depth of approximately 100 A.

While the heat treatment did 1not convert every nonwettable web into a wettable one, the procedure was successful for the two lo-'est molecular weight additives. Whether or not such treatment can be used depends, at least in part, on whether or not the additive has segregated to the subsurface sufficiently close to the effective surface to permit a gentle heat treatment to move the material into the effective surface region. Such segregation in turn is in 1.rt dependent upon the diameter of the fibers, i.e., 25 the time the fibers remain in a molten state. Thus, the choice of additive and heat treatment conditions is, of neocessity, somewhat empirical.

The ability of additive to be moved from the subsurface to either the effective surface or the interfacial surface, or both, expands the types of products based on nonwoven webs prepared in accordance with the present invention. A few exmmples in the area of household and industrial wipes will serve by way of illustration: a wipe consisting of a single polyolefin nonwoven web prepared in accordance with the present invention, in which additive is present in either or both of the effective .i'91surfaces and the interfacial surfaces of the fibers the wipe is hydrophilic or water wettable and is suited for washing or cleaning tasks using aqueous cleaning solutions; a wipe consisting of a single polyolefin nonwoven web prepared in accordance rith the present invention, in which additive is present in the subsurface of the fibersthe web is hydrophobic or oleophilic and is suited for cleaning oily surfaces, but on washing the wipe is converted to a hydrophilic wipe because the heat of the washing or drying environment causes additive to migrate from the fiber subsurface to either or both of the fiber effective surface and interfacial surface, which conversion aids in the removal of oily residues from the wipe; and a wipe consisting of two polyolefin nonwoven layers, one prepared from virgin polymer and the other consisting of a web as described in either or (2) above in the first instance, the wipe will be effective Sfor both water-soluble or water dispersible substances and Soily substances, depending on which layer is used as the wiping layer, and in the second instance, tha wipe can be converted to a wipe of the first instance by laundering.

B. Meltblown Fibers from Pilot-Scale Apparatus P Examples 262-297 SSince the above bench-scale meltblowing experiments in Sgeneral were successful, meltblowing trials were conducted on a pilot-scale meltblowing apparatus essentially as 4 described in U.S. Patent No. 4,663,220, which is incorp- S 30 orated herein by reference. Briefly, such meltblowing was accomplished by extruding a composition (or a simple mixture) through a 0.75-inch (19-mm) diameter Brabender extruder and then through a meltblowing die having nine extrusion capillaries per linear inch (approximately capillaries per linear cm) of die tip. Each capillary had a diameter of about 0.0145 inch (about 0.37 mm) and a -92- S1 length of about 0.113 inch (about 2.9 mm). The process variables in general were as follows: polymer extrusion rate, 2.5-3.5 g per capillary per minute; polymer extrusion temperature, 250-300 depending upon the polymer employed; extrusion pressure, 490-510 psig; die tip temperature, 270-275°; attenuating air temperature, 304-310°; attenuating air pressure, 8-11 psig; and forming distance, 20-40 cm.

The collecting arrangement consisted of a rotating 15.2-cm wide drum having a diameter of 76.2 cm. The surface of the drum was a screen.

The polymer and additive typically were mixed by one S° of several methods before introducing the mixture to the feed hopper of the extruder. In the first (method a standard porta.b,e cement mixer was charged with 50 pounds of the polymer in pellet form. The mixer then was started o n« 20 and charged with the desired amount of additive. Mixing was allowed to continue for 20 minutes, after which time the mixtce was removed from the mixer and stored in plastic-lined boxes. In a variation of that method, the additive was used in an amount higher than that intended for melt-processing to give a stock mixture. The stock mixture then was mixed in a similar fashion with additional ,polymer in a ratio calculated to give the desired final additive concentration (method In the third (method a metered stream of additive was pumped into the feed hopper about 15 cm above the feed screws as polymer pellets flowed downward by gravity into the screws. All three methods worked equally well, ,although method C was used with only one additive.

In each case, a coherent web was obtained which had a basis weight in the range of from about 20 to about g/m 2 Wettability was estimate' means of the water -93- 196 PPA AlO 197 PPA A10 3 drop test. The trials are summarized in Table 30, along with the results of the water drop test..

Table Summary of Pilot-Scale Meltblowinr Trials Polymer Additive Example Code Code Wt.% Wettability 262 PPA All 2 Wettable 263 PPA All 3 Wettable 264 PPA All 5 Wettable 265 PPB All 2 Wettable 266 PPB All 3 Wettable 267 PPB All 5 Wettable 268 PPA A18 1 Wettable 269 PPA A18 3 Wettable 270 PPA A18 5 WettabLe 271 PPB A1,8 1 Wettable 272 PPB AI8 3 Wettable 273 PPB A18 5 Wettable 27 P 2 IWtal 274 PPA A21 1 Wettable 275 PPA A21 3 Wettable 27 tP 2 Wtal 4f,277 PPC A21 1 Wettable 278 PPC A21 3 Wettable ~'279 PPC A21 5 Wettable 2 8 P 0 1W t a l 281 PPA B01 3 Wettable 282 PPA B01 3 Wettable 283 PPB B01 1. Wettable 284 PPB 501 3 Wettable 285 PPB B01 5 Wettable 286 PPC B01 1 Wettable 287 PPC 501 3 Wettable 288 PPC 501 5 Wettable 289 PPA B04 1 Nonwettable -94- -y i~ 290 PPA B04 3 Nonwettable 291 PPA B04 5 Nonwettable 292 PPA B05 1 Nonwettable 293 PPA B05 3 Nonwettable 294 PPA B05 5 Nonwettable 295 PPA C01 1 Nonwettable 296 PPA C01 3 Nonwettable 297 PPA C01 5 Nonwettable The results obtained are consistent with the benchscale meltblowing experiments. Single additives having molecular weights of the order of 3,000 or higher do not segregate to the interfacial surface or effective surface when fiber diameters are relatively small, as they are in typical meltblowing processes.

C. Spunbonded Fibers from Pilot-Scale Apparatus t a Sa Examples 298-365 S 20 Spunbonded trials were conducted on a pilot-scale 4 4 S' apparatus essentially as described in U.S. Patent No.

4,360,563, which is incorporated herein by reference.

'at The polymer and additive typically were mixed by one of the methods described above with respect to Examples 25 262-297, inclusive.

In each case, a web was obtained which had a basis weight in the range of from about 14 to about 60 g/m 2 In some cases, webs of different basis weights were made during a trial by changing the velocity of the forming wire. Typical basis weights thus prepared were 14, 19, S36, 47, and 59 g/m 2 Wettability was estimated by means of the water drop test.

Unlike the meltblown trials, however, it was discovered that when the additive level was greater than 1 percent by weight, there was no web integrity;, that is, the web simply fell apart upon attempting to remove it i- I from the forming wire, even when excellent fiber formation was obtained. The problem was overcome by running the web under a heated compaction roll before removing it from the forming wire. Thus, all of the spunbonded examples in which additive levels were greater than 1 percent by weight utilized a heated compaction roll. While a compaction roll temperature of about 66' was employed,'lower or higher temperatures can be used.

The trials are summarized in Table 31, along with the results of the water drop test; because wettability was independent of web basis weight, the latter is not included in the table.

Table 31 15 Summary of Pilot-Scale Spunbonding Trials 40 9 4 49I .4 44o 04 0 09 PO O 0s I *b 4

I

44*1 4 4- Example 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 Polymer -ode

PPA

PPA

PPC

PPC

PPD

PPD

PPA

PPA

PPA

PPD

PPD

PPD

PPE

PPE

PPA

PPA

PPA

PPA

Additive Code Wt. A05 1 A05 3 A05 1 A05 3 A05 1 A05 3 A08 0.75 A08 1 A08 3 A08 0.75 A08 1 A08 3 A08 1 A08 3 A10 0.5 A10 0.75 A10 1 A10 1.5 Wettability Wettable Wettable Wettable Wettable Wettable Wettable Wettable Wettable Wettable Wettable Wettable Wettable Wettable Wettable Slowly Wett.

Wettable Wettable Wettable 9 4 4 -96- 316 PPA A10 2 Wettable 317 PPA A10 3 Wettable 318 PPE A10 0.5 Slowly Wett.

319 PPE A10 0.75 Wettable 320 PPE A10 1 Wettable 321 PPE A10 1.5 Wettable 322 PPE A10 2 Wettable 323 PPE A10 3 Wettable 324 PPE All 0.5 Slowly Wett.

325 PPE All 0.75 Wettable 326 PPE All 1 Wettable 327 PPE All 1.5 Wettable 328 PPA All 2 Wettable 329 PPA All 3 Wettabl 330 PPD All 0.5 Slowly Wett.

331 PPD All 0.75 Wettable 332 PPD All 1 Wettable 333 PPD All 1.5 Wettable 334 PPD All 2 Wettable 335 PPD All 3 Wettable 336 PPE All 0.5 Slowly Wett.

337 PPE All 0.75 Wettable 338 PPE All 1 Wettable 339 PPE All 1.5 Wettable 340 PPE All 2 Wettable 44A341 PPE All 3 Wettable 342 PPA A14 1 Wettable 343 PPA A14 3 Wettable 344 PPD A14 1 Wettable 345 PPD A14 3 Wettable 346 PPA B01 1 Wettable 347 PPA B01 3 Wettable 348 PPA B01 5 Wettable 349 PPD B01 0.5 Wettable 350 PPD B01 1 Wettable 351 PPD B01 2 Wettable -97- 352 353 354 355 356 357 358 359 360 361 362 3 6 3 a 3 6 4 a 365 b

PPD

PPD

PPA

PPA

PPA

PPA

PPA

PPA

PPA

PPA

PPA

PPA

PPA

PPA

B01 3 B01 5 B04 1 B04 3 B04 5 B05 1 B05 3 B05 5 C01 1 C01 3 C01 5 B04 0.33 0.33 C01 0.33 B04 0.67 0.67 C01 0.67 B04 1 B05 1 C01 1 also contained dioxide.

also contained Wettable Wettable Wettable Wettable Wettable Wettable Wettable Wettable Nonwettable Nonwettable Nonwettable Wettable Wettable Wettable 2.5 percent by 2 percent by weight 4* o 0 ft 44* 4 4 4*i 4 44g 44D 4 44 4 4 4 4* 4 4.i aThe composition weiht titanium bThe composition titanium dioxide Because spunbonded fibers typically have larger diameters on the average than meltblown fibers, the spunbonded webs were wettable or slowly wettable with additives having molecular weights up to about 3,000. However, the use of an additive having a molecular weight of about 8,000 did not produce a Wettable Web.

In order to further investigate the ability of a gentle post-formation heat treatment to bring additive to the effective surface and/or interfacial surface, ESCA analyses were carried out on three of the spunbonded webs.

The websi then were heated at 110' for 1 minute in a labora- -98tory oven and the heated webs were subjected to ESCA analyses. The results of the ESCA analyses before and after heating are summarized in Table 32.

Table 32 Summary of ESCA Analyses Before and After Heating ESCA Analyses Before and After Heatinq a Before Heating After Heatin Example C %0 Si C Si Inc.b 325 95 3.2 1.6 91 6.6 2.8 326 95 3.9 1.6 79 15 6.5 306 327 84 11 5.0 76 17 7.4 48 aIn atom percent.

o bpercent silicon increase in first 100 A of surface.

4 The data in Table 32 clearly show the remarkable 0increase in silicon concentration within the first 100 A St 20 of the surface upon exposing a web to a mild heat treat- Sment, especially at an additive level of 1 percent by weight.

Because spunbonded webs commonly are employed as liners in disposable diapers, the mild heat treatment 4 25 phenomenon was investigated by two different methods in S4 conjunction with a simple diaper run-off test. The diaper .run-off test involved removing the liner from a standard KIMBEE diaper. The linerless diaper was mounted on a plate which was inclined at a 45° angle, the back edge of the diaper being at the top of the plate. The test fabric was laid over the diaper. A reservoir containing 100 ml of 0.85 percent (weight per volume) saline (cat. no. SS-442- Fisher Scientific, Pittsburgh, Pennsylvania) at 37' was located at the top of the plane 2 inches (5.1 cm) above the uppermost edge of the diaper's absorbent pad. The saline then was allowed to run out of the reservoir in a -99- _i i rr steady stream. Fluid which was not retained by the diaper was collected and measured, the volume of which was the runoff value.

In the first method, samples of a spunbonded nonwoven web made from a compcsition of the present invention and having a basis weight of 27 g/m 2 were heated in an oven at two different temperatures. Run-off measurements were nade on samples which had not been heat treated and those which had. In every case, the additive was All and the polymer was PPE. The results are summarized in Table 33.

Table 33 Summary of Results of Run-Off Test After First Heat Treatment Method Web Add. O'ven Heating Run-Off Example Levela Temp.. Time Test, ml S 324 0.5 l00 b 80 3 min. 20-30 0.5 110 30 sec. 30-40 S* 325 0.75 70-80 b 0.75 80 3 min. 0-1 0.75 110 30 sec. 40-50 326 1 25 1 80 3 min. 0 1 110 30 sec. 0 aln weight percent.

bcontrol.

The efficacy of the heat treatment in each case is readily apparent. It appears that 80° for 3 minutes is more effective than 110" for 30 seconds, at least for the webs having the two lowest concentrations of additive.

Either temperature treatment, however, converts the web containing 1 percent by weight of additive into a highly wettable, highly efficient transfer layer.

-100i

I

In the second method, samples in continuous roll form of the same webs used in the first method were passed over two steam cans in series which were heated by steam at a pressure of 5 psig. The surfaces of the cans were at about 85*. Each sample was passed over the cans at two different line speeds, after which the run-off test was performed. The results are summarized in Table 34.

Table 34 Summary of Results of Run-Off Test After Second Heat Treatment Method Web Add. Line Run-Off Example Levela Speed, m/min Test, ml 324 0.5 100 b 9 80-90 4.5 80-90 4 325 0.75 0.75 9 0.75 4.5 1 326 1 20-30 b 1 9 5-10 1 4.5 amn weight percent.

bControl.

The results from the second method were similar to those of the first rmethod in that the concentration of additive leading to the most efficient transfer layer was 1 percent by weight; the slower line speed gave slightly 4 °better results at that concentration.

Because oi the success with the Si-SEM procedure With a melt-pressed film, a similar effort was carried out with spunbonded fibers prepared from a composition containing a mixture of additives in polymer PPA, Example 365.

In this case, a bundle of fibers was collected before they -101reached the forming wire. The bundle was cut and inserted into a small plastic tube about 19 mm long and having an inside diameter of about 3 mm, thereby packing the tube with fibers. The packed tubing was placed in liquid, nitrogen, removed, and cut with a razor blade. The sample was placed on the SEM mount and sputtered with carbon before carrying out the analysis. A diagrammatic representation of the results of the analysis is shown by Figure 9. In Figure 9, the fibers 50 are bilobal in cross-section.

As with the film analysis, each of dots 51 represents the presence of silicon atoms.

It is clear that the additives included in the composition from which the fibers of Example 365 were prepared have segregated preferentially to the surface region of the film. While the core region is not as devoid of silicon I as was the core region of the film, there clearly is a lower concentration of the additives in the core. region than in the area at or near the surfaces of the fibers.

This tesult was expected, however, because of the relatively rapid formation of the fibers as compared to the film 11formation time. That is, the fibers remained in a molten state for a time which was much shorter than the time the film remained in a molten state. The fact that the additives segregated to the surfaces of the fibers in such a short time is, as already pointed out, a result of the influence of shear during the extrusion process.

Two samples of fibers from the spunbonded trials were submitted for analysis by RES. The results are summarized in Table -102- Icl-~rrs i ir., Table Summary of RBS Analyses on Spunbonded Fibers rtmi Connentration Atom Atomic Concentration Atom Example Depth, A 329 0-1000 1000-3000 >3000 329 b 0-1000 1000-2000 >2000 364 0-250 250-900 900-1600 1600-2900 2900-4900 >4900 aThis concentration was

C

30 30 30 29 29 30 28 28 29 29 29 29 at or 0 0.7 0.2 0.2 0.3 0.1 0.1 3.6 2.2 1.5 1.0 0.8 0.8 near Si Ti 0.28 0.01 a 0.06 0.02 0.03 0.03 0.13 0.01 a 0.02 0.02 0.02 0.02 1.94 0.02 0.90 0.02 0.45 0.05 0.37 0.05 0.26 0.05 0.12 0.05 the detection

SI

I 41 Q I Z 4 1

I

limit; the actual concentration may be considerably lower.

bA second analysis was carried out on the same sample.

From the data for the two analyses on the same sample, it appears that the RBS procedure causes some loss of additives as evidenced by the decreased silicon concentra- *.tion values. Thus, it is probable that the concentration values are lower than the actual concentrations. Nevertheless, the procedure is helpful because it gives at least a qualitative view of the segregation of the additives in the surface region and the core region adjacent thereto.

The RBS data from Table 35 for the webs of Examples 329 and 364 were plotted as already described. The plots for the two analyses of the web of Example 329 are shown as Figures 10A and lOB. The plot for the analysis of the web of Example 364 is shown as Figure 11.

-103- The plots are similar to that for the RBS analysis of the film of Example 173. Figur~e 8 and 10A are especially similar, although in the latter the concentration of silicon diminishes to the minimum concentration at around 2,000 A, rather than at around 1,000 A. In Figure 11, it is seen that the silicon concentration diminishes more slowly with depth, although all of the plots resulted in curves having similar shapes.

The webs from Examples 329 and 364 also were submitted for ESCA and bulk elemental analyses. The results of these analyses are shown in Table 36.

Table 36 Summary of ESCA Data and Elemental Analyses for the Webs of Examples 329 and 364 ESCA Data Bulk Elemental Anal.

Example %C %0 Si 1 %si 329 77 17 6.6 83.84 13.23 0.35 364 62 27 11 82.23 13.40 0.89 D. Meltblown Fibers fro Pilot-Scale Coforming Apparatus Examples 366-439 A number of larger-scale meltblowing runs were carried out on a coforming apparatus of the type described in U.S.

Patent Nos. 4,100,432 and 4,663,220, the latter patent 6 0 30 having been identified and incorporated herein by reference S* in regard to Examples 262-297, inclusive; the former patent also is incorporated herein by reference.

Meltblowing was accomplished by extruding the composition from a 1.5-inch (3.75-cm) Johnson extruder and through a meltblowing die having 15 extrusion capillaries per linear inch (about 5.9 extrusion capillaries per linear -104cm) of die tip. Each capillary had a diameter of about 0,018 inch (about 0.46 cm) and a length of about 0.14 inch (about 3.6 mm). The composition was extruded through the capillaries at a rate of about 0.5 g per capillary per minute at a temperature of about 184'. The extrusion pressure exe ted on the composition in the die tip was in the rar.ge of from about 180 to ab<ut 200 psig. The composition viscosity in the die tip under these conditions was about 500 poise. The die tip configuration was adjusted to have a positive perpendicular die tip distance of about 0.01 inch (about 0.25 mm). The air gaps of the two attenuating air passageways were adjusted to be about 0.067 inch (about 1.7 mm). Forming air for meltblowing the composition was supplied to the air passageways at a terperature of about 209° and a pressure of about 2 psig. The fibers thus formed were deposited on a forming screen drum which was approximately 18 inches (46 cm) below and 20 inches S'(51 cm) back from the die tip.

*t The .ore significant process variables generally were as follows; barral temperature, 280-300°; die temperature, 285-316°; melt temperature in die, 275-316*; barrel pressure, 220-570 psig; die pressure, 55-130 psig; primary air temperature, 235-349"; primary air pressure, 3-4.5 psig; throughput, 7-360 g per cm of die width per hour; forming distance, 36 cm; and S 30 basis weight, 27-85 g/m 2 with the more typical basis weights being 27, 51, and/or 85 g/m 2 The compositions which were meltblown were prepared by melt-blending polymer and additive(s) as described in Examples 50-130, inclusive. Coherent webs were formed in each case. As with previous trials, wettabili.ty of the formed webs was estimated by the water drop test as appropriate. The compositions meitbiown and the results of the water drop test are summarized in Table 37.

Table 37 Summary of Me,,cblowing Trials on Pilot-Scale Coforming Apparatus Ii 444 4 o 41 44~ 4 1 4 44 j 44 41 44 4

I

4.

4 I j I I I 44~

I

4444 4 4444 4 44 4 4 4 Examplet 366 367 368 369 370 371 372 373 374 375 20 376 377 378 379 380 381 382 333 384 385 30 386 387 388 389 390 391 392 Comp.

Code PP2 8-1 PP29-1 PP30-1 PP31-1 PE18 -1 PE19-1 PE20-1 PP32-1 PP33-1 PP3 4-2.

PP35-1 PP36-1 PP3 7-1 PE21-1 PE22-1 PP38-1.

PP39-1 PP40-t PP41-1 PP42-1 PP43-1 PP4 4-1 PP45-1 PP46-1 PP4 7-1 PE 23-1 PE 24-1 Polymer Code

PPA

PPA

PPA

PPA

PEA

PEA

PEA

PPA

PPA

PPB

PPB

PPc

PPC

PEA

PEA

PPA

PPA

PPc

PPC

PPA

PPA

PPC

PPc

PPA

PPA

PEA

PEA

Code(s) Wt. Wettability A21 1 Wettable A21 3 Wettable A21 5 Wettable A21 12 Wettable A21 1 Wettable A21 3 Wettable A22. 5 Wettable So2., 3 Wettable 801 5 Wettable 801 3 Wettable B01 5 Wettable B01 3 Wettable B01 5 Wettable 801 3 Wettable 1301 5 Wettable B02 3 Wettable B02 5 Wettable B02 3 Wettable 802 5 Wettable B03 3 Wettable B03 5 Wettable B03 3 Wettable B03 5 Wettable 804 3 Nonwettable 804 5 Nonwettable B04 3 Npnwettable B04 5 Nonwettable -106g/m 2 Wettability was estimate' means of the water, -93- ~mri I i 0 0 00 4 4 1 44 *4 4 4 04 4 o 4I 4440 4 441 44 4 4I 4 4I 4 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 20 412 413 414 415 416 417 418 419 420 421 30 422 423 424 425 426 427 428 PP48-1 PP49-1 PE25-1 PE26-1 PP50-1 PP51-1 PP52-1 PP53-1 PP54-1 PP55-1 PP56-1 PP57-1 PP58-1 PP59-1 PP60-1 PP61-1 PP62-1 PP63-1 PP64-1 PP65-1 PP66-1 PP67-1 PP68-1 PP69-1 PP70-1 PP71-1 PP72-1 PP73-1 PP74-1 PP75-1 PP76-1 PP77-1 PE27-1 PE28-1 PE29-1 PP78-1

PPA

PPA

PEA

PEA

PPA

PPA

PPC

PPC

PPA

PPA

'PPC

PPc

PPA

PPA

PPC

PPC

PPA

PPA

PPA

PPc PPc

PPA

PPA

PPC

PPc

PPA

PPA

PPc

PPC

PPA

PPA

PPA

PEA

PEA

PEA

PPA

B05 B05 B05 B05 B06 B06 B06 T06 B07 8 B07 B07 B08 B08 B08 B08 B09 B09 B09 B09 B09 B10 B10

BIO

BI0 BlI B11 B11 B11 CO1 col Co1 Col Co1 Co1 D03 3 Nonwettable 5 Nonwettable 3 Nonwettable 5 Nonwettable 3 Nonwettable 5 Nonwettable 3 Nonwettable 5 Nonwettable 3 Nonwettable 5 Nonwettable 3 Nonwettable 5 Nonwettable 3 Nonwettable 5 Nonwettabile 3 Nonwettable 5 Nonwettable 2 Nonwettable 3 Nonwettable 5 Nonwettable 3 11onwettable 5 Nonwettable 3 Nonwettable 5 Nonwettable 3 Nonwettabie 5 Nonwettable 3 Nonwettable 5 Nonwettable 3 Nonwettable 5 Nonwettable 1 Nonwettable 3 Nonwettabie 5 Nonwettable 1 Nonwettable 3 Nonwettable Nonwettable Wettable -107- 289 PPA B04 1 Nowtae Nonwettable -94- 429 430 431 432 433 434 PP79-1 PP8O-1 PP82-2 PP84-2 PP86-2 PP90-3

PPA

PPA

PPA

PPA

PPA

PPA

435 15 4* 4 a 4 4 4 4 44

I

44 4 4 I 4 20 44 4 436 437 438 PP92-3 PP93-3 PE30-3 PE3 1-3 PE32-3

PPA

PPA

PEA

PEA

PEA

D04 DO5 B02 B11 B06 Bl0 B10 B11.

DO04 B0 5 Co 1 B04 COl B04 BO5 COl B04

DOS

Co 1 B04 B0 5 col DO04 Co 1 3 3 1.5 1.5 1.5 0.33 0. 33 0.33 1 1 1 1.67 1. 67 1.67 0.33 0.33 O0.33 1 1 1 1. 67 1.67 1.67 N/Aa

N/A

Wettable Wettable Wettable Wettable Wettable Wettable Wettable Wettable Wettable 439 4 4 I a4 t 4 9 Not applicable.

The results of the meltblowing trials on the coforming 30 apparatus with additives which'impart water wettability to the surfaces of the fibers were consistent with those of the previous meltblowing trials.

.In order to verify the presence of additive D04 on the surfaces of the fibers, ESCA and bulk elemental analyses were run on the web from Example 429. Similar analyses -108-

I

were carried out with the web from Example 430 as a control.

The results of these analyses are summarized in Table 38.

Table 38 Summary of ESCA and Bulk Analyses on the Webs from Examples 429 and 430 Example 429 430 Controla apolymer ESCA Data Bulk Elemental Analyses F Si C F Si 73 11 6.9 83.66 0.99 0.50 69 16 84.72 1.06 100 98 PPA which did not contain any additive.

110 a a o a 0 000 00 0 a o 0 00 0 a0 o e 00 0 0 *400 4 o 0 0 15 According to the analytical data for the web from Example 429, it is evident that additive D04 has segregated to the surface region; i.e, the first 100 A of the surface as measured from the interfacial surface. The web from Example 430 also contained a substantial amount of additive, 20 in this case DO5, in the same surface region.

As already pointed out, however, additive DOS moved to the surface of the fibers because it is incompatible with the polymer. Such incompatibility resulted in poor web formation; that is, the web was characterized by nonuniform fiber diameters, an unusually high proportion of discontinuous fibers, and a substantial amount of shot.

.The process was characterized by a frequent, almost explosive, expulsion of polymer from the die orifices which is potentially hazardous to the operators.

30 E. Coformed Webs from Pilot-Scale Coforminq Apparatus Examples 440 and 441 Two fibrous coformed nonwoven webs were formed by meltblowing a composition of the present invention and incorporating polyester staple fibers therein.

-109- Meltblowing was accomplished as described for Examples 366-439, inclusive. In each case, the polymer was PPA and the additive was B01 at a level of 3 percent by weight.

The more significant meltblowing process conditions were approximately as follows: die tip temperature, 296"; primary air temperature, 284°; primary air pressure, 3.5 psig; throughput, 179 g per cm of die width per hour; horizontal forming distance, 51 cm; and vertical forming distance, 43 cm.

Following the procedure illustrated by Figure 5 of said U.S. Patent No. 4,663,220 and described therein, 3inch (7.6-cm) long, 40 denier per filament polyester staple (type 125, E. I. Du Pont de Nemours Co., Inc., Wilmington, Delaware) was incorporated into the stream of meltblown fibers prior to deposition upon the forming drum. The polyester fibers were first formed by a Rando Webber mat- S forming apparatus into a mat having a basis weight of 20 about 100 g/m 2 The mat was fed to the picker roll by a feed roll which was positioned about 0.13 mm from the picker roll surface. The picker roll was rotating at a rate of about 3,000 revolutions per minute and fiber 1 4 transporting air was supplied to the picker roll at a pressure of about 2.5 psig. While actual measurement of the position of the nozzle of the coform apparatus with respect to the stream of meltblown fiber was not made, it was estimated to be about 5.1 cm below and about 5.1 cm away from the die tip of the meltblowing die.

Two coformed webs were prepared, both of which had a width (cross-machine direction) of about 51 cm. The first web was composed of about 70 percent by weight of the polyester staple fibers and about 30 percent by weight of the meltblown fibers and the second web was composed of about 50 percent by weight of each of the two types of -110- 350 PPD B01 1 Wettable 351 PPD B01 2 Wettable -97fibers. Each web had a basis weight of about 100 g/m 2 and wet immediately when subjected to the water drop test.

Although not described in detail here, other coformed webs, were similarly prepared with staple fiber:meltblown fiber ratios of 85:15, 75:25, 65:35, and 15:85. In addition, webs utilizing other sources of polyester staple fibers were prepared at each of the foregoing ratios.

Such other polyester staple fibers were as follows: 3.25-inch (8.3-cm) x 25 denier (Eastman Chemical Products, Inc., Kingsport, Tennessee); type ES 1.5-inch (3.8-cm) x 1.5 denier (Chisso Corporation, Tokyo, Japan); and type 41-D 1.5-inch (3.8-cm) x 1.5 denier (Eastman Chemical Products, Inc.).

Example 441 The procedure of Examples 440 and 441 was repeated, except that the composition was 3 percent by weight of additive B01 in polymer PEA, the secondary fibers were wood pulp fibers, and a dual meltblowing die/center secondary fiber duct arrangement was employed. The composition was meltblown through one die at a throughout of either 179 or 894 g per cm per hour. In either case, the melt temperature was about 288°. The die tip pressure was 0 either 90 or 220 psig, depending upon the throughput.

Polymer PPC was meltblown through the other die at a throughput of from about 179 to about 716 g per cm per hour. The melt temperature was in the range of from about 246 to about 274" and the primary air temperature was in the range of from about 280 to about 302°. The primary air pressure was in the 2-5 psig range.

Coformed webs containing pulp:polymer ratios of 70:30 and 90:10 were prepared. The webs wet immediately and the composition did not impede the absorbency of the web.

-111- V. Evaluation of Known Material In conclusion, an additive of the type described in U.S. Patent No. 4,659,777 was evaluated both in meltpressed films and fibers from the bench-scale meltblowing apparatus. The additive was a poly(2-ethyloxazoline)polydimethylsiloxane-poly(2-ethyloxazoline) blockcopolymer, each of the blocks having a molecular weight of about 3,000.

Example 446 A melt-pressed film was prepared successfully as described for Examples 131-176, inclusive. The material contained 10 percent by weight of the additive in po!ymer

PPA.

The surface energy of the film was estimated by means of Pillar wetting agents (Pillar Corporation, West Allis, SWisconsin) to be 34-35 dynes per cm. The value for virgin polymer is about 30. The film then was subjected to ESCA analysis. None of the additive was found to be in the first 100 A below the interfacial surface.

Example 447 Meltblown fibers were prepared with a bench-scale apparatus as described for Examples 178-239, inclusive.

The composition consisted of 3 percent by weight of the additive in polymer PPA. Meltblowing was conducted at an air pressure of 35 psig and melt temperatures of 264, 285, and 308". Although webs were obtained in each case, web quality was poor and decomposition of the additive occurred Sat each melt temperature. Decomposition was especially severe at the highest temperature. No analyses of the webs were attempted since the additive obviously is unsuited for melt-processing procedures and does not segregate to the surface.

-112i F VI. Hot-Stage Microscopy Study of a Composition Described in U.S. Patent No. 4.070.218 One last hot-stage microscope analysis needs to be described. The composition consisted of polymer PPA with 3 percent by weight of Triton X-102 (Rohm and Haas Co., Philadelphia, Pennsylvania), a surfactant which is commonly used to make polypropylene wettable by leans of the blooming technique already described, The representations of the photomicrographs are shown in Figures 12A and 12B. Globules 121 of the surfactant are seen in both Figures; some debris 122 in Figure 12A also is apparent. The most noteworthy fact about the two Figures is that the surfactant not only is incompatible with the polymer at 160°, but is even less compatible at about 220°. In view of Figures 12A and 12B, it is easy to understand why a blooming process is required to bring the surfactant to the surface of the fiber or film and why the material migrates back into the polymer.

It now should be evident that the additives described herein and the compositions of the present invention function in a manner which is different from the materials previously added to thermoplastic polymers to alter the surface characteristics of shaped articles, such as fibers and films, made therefrom. Moreover, the compositions of the present invention permit the control of the segregation phenomenon, which control was not possible with prior art .procedures. Thus, the method of the present invention is, in reality, very different from that of said U.S. Patent No. 4,070,218. Moreover, HLB terminology is not applicable 30 to the additives employed in the present invention.

Having thus described the invention, numerous changes and modifications thereof will be readily apparent to those having ordinary skill in the art without departing from the spirit or scope of the invention. For example, the compositions useful in the present invention also can contain fillers, colorizers, stabilizers, and the like.

j r

V

V 1(1 V 4 4 4, 4L 4 -113- -L i

Claims (39)

1. A method of forming a nonwoven web from a surface-segregatable, melt-extrudable thermoplastic compo- sition which comprises at least one thermoplastic polymer and at least one siloxane-containing additive having at least two moieties, A and B, which method comprises the steps of: 4 44 Si 15 4, 4 4 #1 *4

2-0

4. 4, 8 8 forming fibers by extruding a molten thermoplastic composition through a die; drawing said fibers; collecting said fibers on a moving foraminous surface as a web of entangled fibers, which fibers have less than abu 0.35 percent by weight, based on the weight of said fibers, of solvent-extractable additive at their interfacial surfaces and have surface properties charac- teristic of said at least one thermoplastic polymer; and heating said web at a temperature of from @abou 27 to-aout 950 C for a period of time sufficient to provide at least about0.35 percent by weight, based on the weight of said fibers, of solvent- extractable additive at the interfacial surfaces of the fibers, which fibers have a surface property characteristic of said at least one additive as a consequence of said heating; 1 8 h ii 4t 1 in which: said additive is compatible with said polymer at melt extrusion temperatures but is incompatible at tempera- tures below melt extrusion temperatures, but each of said moiety A and moiety B, if present as separate compounds, would be incompatible with said polymer at melt extrusion temperatures and at temperatures below melt extrusion temperatures; -114- i; -r- moiety B has at least one functional group which imparts to said additive said at least one characteristic; the molecular weight of said additive is in the range of from-about-400 to abot 10,000; and said additive is present in said thermoplastic composition at a level of from about 0.5 to bauet 2 percent by weight, based on the weight of said polymer. 2. The method of claim 1, in which said polymer is a polyolefin. 3. The method of claim 1, in which said polymer is a polyester. 4. The method of claim 1, in which said heating provides at least abu4 0.75 percent by weight of solvent- extractable additive at the interfacial surfaces of said fibers. *I

5. The method of claim 1, in which said heating *provides at least about 1 percent by weight of solvent- extractable additive at the interfacial surfaces of said fibers.

6. The method of claim 1, in which said additive has a molecular weight of from au 500 to a u 1,000.

7. The method of claim 1, in which said moiety A .comprises at least one tetrasubstituted disiloxanylene group, optionally associated with one or more groups selected from the group consisting of trisubstituted silyl and trisubstituted siloxy groups, the substituents of all such groups being independently selected from the group consisting of monovalent alkyl, cycloalkyl, aryl, and heterocyclic groups, each of which is substituted or unsubstituted, and moiety B. -115-

8. The method of claim in which said sub- stituents independently are selected from the group consist- ing of monovalent alkyl groups having from 1 to 3 carbon atoms and said moiety B.

9. The method of claim 1, in which said additive contains a plurality of groups selected from the group consisting of the following general formulae: BI-, B 2 R 1 R 2 -Si, (R 3 (R 4 (R 5 )Si-, (R 6 (R 7 (R 8 Si-O-, [-Si(R 9 and S. (-Si(Rii) (B 3 in which each of R 1 and R 2 independently is a monovalent group selected from the group consisting of hydrogen, alkyl, cycloalkyl, aryl, and heterocyclic groups, each of which, except for hydrogen, is substituted or unsubsti- tuted; each of R 3 -R 5 inclusive, independently is a mono- valent group selected from the group consisting of alkyl, cycloalkyl, aryl, and heterocyclic groups, each of which is substituted or unsubstituted, and B 4 each of R 6 -Rli, inclusive, independently is a monovalent group selected from the group consisting of alkyl, cycloalkyl, aryl, and 'heterocyclic groups, each of which is substituted or unsubstituted; each of a and b independently represents an integer from 0 to46a 70 which indicates only the quantity of the respective group present in the additive without indicating or requiring, in instances when an integer is greater than 1, that such plurality of the respective group are connected to one another to form an oligomer or polymer or that all of such groups have identical sub- stituonts; and each of BI-B 4 inclusive, independently is a moiety which imparts to the additive at least one desired -116- characteristic; with the proviso that such plurality of groups results in at least one tetrasubstituted disilox- anylene group. The method of claim 1, in which said additive is a compound having the general formula, R12 B 5 -0-(-Si-O-)c-B6 R13 in which each of R 12 and Ri 3 independently is a monovalent group selected from the group consisting of hydrogen, alkyl, cycloalkyl, aryl, and heterocyclic groups, each of which, except for hydrogen, is substituted or unsubsti- tuted; each of B 5 and B 6 independently is a monovalent group having a desired characteristic; and c represents an integer from 2 to about

11. The method of claim 10, in which said additive has a molecular Weight of from abot 500 to 4A 1,000.

12. The method of claim 1, in which said additive is a compound having the general formula, R17 R19 SR4-si-- e-SI-R 2 1 I I I I SR6 R 18 B 7 R22 in which each of R 14 -R 22 inclusiae, independently is a monovalent group selected from the group consisting of 1o hydrogen, alkyl, cycloalkyl, aryl, and heterocyclic groups, each of which, except for hydrogen, is substituted or unsubstituted; B 7 is a monovalent g'oup having a desired -117- i cnaracteristic; d represents an integer from~ 0 to -ao~t and e represents an integer from 1 toaot'0

13. The method of claim 1, in which said additive is a ir-mpound having t1.he general formula, R 2 3 -SiE f-B 8 3 R 2 th which each of R 2 3 -R 2 5 inclusive, independently is a onovalent group selected from the group consisting of hydrogen, alkyl, cycloaltyl, aryl,and heterocyclic groups, characteristic; and f represents an integer from 1 to 14e, The *method of claim 1, in1 which a characteristic of said moiety 13 is hydrophilicity. The method of claim 1, in Which a characteristic 6f said moiety B is Ultraviolet radiation absorption. 4 26. The method of claim 1, In which a characteristic of said moiety B i5 degradation stabilization,

17. saide method of claim 1, in which a characteristic o. sai miet B 'Ls hghhydrophobicity.

18. The method of claim 1, in which a characteristic of said moiety B is a buffering capacity.

19. A method of forming a nonwoven web from a surface-segregatable, melt-eXtrudable thermoplastio compo- sition which comprizes at least one thermoplastic polymer -118- 41 A UrA and at least one siloxane-containing additive having at least two moieties, A and B, which method comprises the steps of: forming fibers by extruding a molten thermoplastic composition through a die; drawing said fibers; .0 collecting said fibers on a moving foraminous surface as a web of entangled fibers, which fibers have at least -abot 0.35 percent by weight, based on the weight of said fibers, of solvent-extractable additive at their interfacial surfaces and have a surface property charac- teristic of said at least on3 additive; and heating said web at a temperature of from abket- 27 to abot 95° C for a period of time sufficient to increase the amount of solvent-extractable 0 additive at the interfacial surfaces of the fiber to at least aboue 0.75 percent by weight, based on the weight of said fibers; rr rp t P t i 6 Fi t Sin which: said additive is compatible with said polymer at m;Ilt extrusion temperatures but is incompatible at tempera- tures below melt extrusion temperatures, but each of said 4 moiety A and moiety B, if present as separate compounds, would be incompatible with said c ymer at melt extrusion temperatures and at temperature bIelow melt extrusion -temperatures; S moiety B has at least one functional group which Simparts to said additive said at least one characteristic; S* the molecular weight of said additive is in the range of from a4.e-400 to abem4 10,000; and said additive is present in said thermoplastic composition at a level of from au- 0.5 to abu 2 percent by weight, based on the weight of said polymer. -119- /V TD i- s i~ ;Lf; -I The method of claim 19, in which said polymer is a polyolefin.

21. The method of claim 19, in which said polymer is a polyester.

22. The method of claim 19, in which said heating provides at least abou4 0.75 percent by weight of solvent- extractable additive at the interfacial surfaces of said fibers.

23. The method of claim 19, in whch said heating provides at least Raou 1 percent by weight of solvent- Sextractable additive at the interfacial surfaces of said fibers.

24. The method of claim 19, in which said additive has a molecular weight of from aboet 500 to abeat 1,000. The method of claim 19, in which said moiety A comprises at least one tetrasubstituted disiloxanylene group, optionally associated with one or more groups selected from the group consisting of trisubstituted silyi and trisubstituted siloxy groups, the substituents of all such groups being independently selected from the group consisting of monovalent alkyl, cycloalkyl, aryl, and .*heterocyclic groups, each of which is substituted or unsubstituted, and moiety B. 4,44 4 t 4

26. The method of claim 25, in which. said sub- stituents independently are selected from the group consist- ing of monovalent alkyl groups having from 1 to 3 carbon atoms and said moiety B. -120- r~r~j.

27. The method of claim 19, in which said additive contains a plurality of groups selected from the group consisting of the following general formulae: B 1 B 2 R 1 R 2 -Si, (R 3 )(R 4 )(R 5 )Si-, (R 6 )(R 7 )(R 8 )Si-O-, [-Si(R 9 and [-Si(R 11 in which each of R 1 and R 2 independently is a mono-vaent group selected from the group consisting of hydrogen, o, alkyl, cycloalkyl, aryl, and heterocyclic groups, each of which, except for hydrogen, is substituted or unsubsti- tuted; each of R 3 -R 5 inclusive, independently is a mono- valent group selected from the group consisting of alkyl, cycloalkyl, aryl, and heterocyclic groups, each of which is substituted or unsubstituted, and B 4 each of R 6 -R 11 r inclusive, independently is a monovalent group selected from the group consisting alkyl, cycloalkyl, aryl, and heterocyclic groups, each of which is substituted or unsubstituted; each of a and b independently represents an integer from 0 to4 a4 70 which indicates only the quantity of the respective group present in the additive without indicating or requiring, in instances when an integer is greater than 1, that such plurality of the respective group are connected to one another to form an oligomer or polymer or that all of such groups have identical sub- stituents; and each of B 1 -B 4 inclusive, independently is a moiety which imparts to the additive at least one desired characteristic; with the proviso that such plurality of groups results in at least one tetrasubstituted disilox- anylene group. -121- 17 4aS- *s 1 ^w

28. The method of claim Op in which said additive is a compound having the general formula, R12 B 5 6 R 13 in which each of R 12 and R 13 independently is a monovalent group selected from the group consisting of hydrogen, alkyl, cycloalkyl, aryl, and heterocyclic groups, each of which, except for hydrogen, is substituted or unsubsti- tuted; each of %y and B 6 independently is a monovalent tt group having a desired characteristic; and c represents an integer from 2 to about

29. The method of claim 28, in which said additive has a molecular weight of fromibe 500 to abeui-1,000. 4 The method of claim 19, in which said additive is a compound having the general formula, R 7 R1 9 r0 I RI4-Si--(si-O-)d-(-Sl-0-)e-SX-R21 I I I R 16 R18 B 7 R22 o> in which each of R 14 -R 22 inclusive, independently is a 0. 0 monovalent group selected from the group consisting of Shydrogen, alkyl, cycloalkyl, aryl, and heterocyclic groups, each of which, except for hydrogen, is substituted or unsubstituted; B 7 is a monovalent group having a desired characteristic; d represents an integer from 0 to ab4e- and e represents an integer from 1 to abae-

31. The method of claim 19, in which said additive is a compound having the general formula, -122- 0M^^ F S I 1 i R24 R 2 3 -Si[(-0-Si-)f-B 8 3 1 in which each of R 23 -R 25 inclusive, independently is a monovalent group selected from the group consisting of hydrogen, alkyl, cycloalkyl, aryl, and heterocyclic groups, each of which, except for hydrogen, is substituted or unsubstituted; B 8 is a monovalent group having a desired characteristic; and f represents an integer from 1 to ab t-

32. The method of claim 19, in which a characteristic of said moiety B is hydrophilicity.

33. The method of claim 19, in which a characteristic of said moiety B is ultraviolet radiation absorption.

34. The method of claim 19, in which a characteristic of said moiety B is degradation stabilization.

35. The method of claim 19, in which a characteristic of said moiety B is high hydrophobicity.

36. The method of claim 19 in which a characteristic of said moiety B is a buffering capacity.

37. A method of forming a nonwoven web comprising the steps of: forming continuous filaments by extruding a molten thermoplastic composition through a die; quenching said continuous filaments to a solid state; drawing said filaments; -123- I Ir I S Io S I _1 composition did not impede the absorbency of the web. -111- collecting said continuous filaments on a moving foraminous surface as a web of entangled fila- ments; and passing said web between a pair of compacting rolls, at least one of which is heated, before removing said web from said moving foraminous surface, said compacting rolls applying heat and pressure to said web sufficient to impart coher- ency thereto; wherein said thermoplastic composition comprises a surface- segregatable, melt-extrudable thermoplastic composition which comprises at least one thermoplastic polymer and at least one additive having at least two moieties, A and B, in which: said additive is compatible with said polymer at melt extrusion temperatures but is incompatible at temper- atures below melt extrusion temperatures, but each of moiety A and moiety B, if present as separate compounds, would be incompatible with said polymer at melt extrusion temperatures and at temperatures below melt extrusion temperatures; 0 moiety B has at least one functional group which 30 imparts to said additive at least one desired character- istic; said additive is a siloxane-containing compound; the molecular weight of said additive is in the range of from-ab.u 400 to -ab.se 10,000; and the weight ratio of said polymer to said additive .is in the range of from about 10 to about 100.

38. The method of claim 37, in which said polymer is a polyolefin.

39. The method of claim 37, in which said polymer is a polyester. -124- ~1 I~I The method of claim 37, in which said additive has a molecular weight of from-aboe" 500 to aboe 1,000.

41. The method of claim 37, in which said moiety A comprises at least one tetrasubstituted disiloxanylene group, optionally associated with one or more groups selected from the group consisting of trisubstituted silyl and trisubstituted siloxy groups, the substituents of all such groups being independently selected from the group consisting of monovalent alkyl, cycloalkyl, aryl, and heterocyclic groups, each of which is substituted or unsubstituted, and moiety B. S42. The method of claim 41, in which said sub- .I stituents independently are selected frm the group consist- ing of monovalent alkyl groups having from 1 to 3 carbon atoms and said moiety B. S43. The method of claim 37, in which said additive contains a plurality of groups selected from the group consisting of the following general formulae: B 1 5 B 2 1(3) R 1 R 2 -Sim, (R 3 (R 4 (P 5 )Si-, (R 6 (R 7 (R 8 I" 10 [-Si(R 9 and (-Si(R 1 I)(B3)-40-b; in which each of R 1 and R 2 independently is a monovalent group selected from the group consisting of hydrogen, alkyl, cycloalkyl, aryl, and heterocyclic groups, each of which, except for hydrogen, is substituted or unsubsti- tuted; each of R 3 -R 5 inclusive, independently is a mono- valent group selected from the group consisting of alkyli, cycloalkyl, aryl, and heterocyclic groups, each of which -125- is substituted or unsubstituted, and B 4 each of R 6 -R 11 inclusive, indeperdently is a monovalent group selected from the group consisting of alkyl, cycloalkyl, aryl, and heterocyclic groups, each of which is substituted or unsubstituted; each of a and b independently represents an integer from 0 to abo4-70 which indicates only the quantity of the respective group present in the additive without indicating or requiring, in instances when an integer is greater than 1, that such plurality of the respective group are connected to one another to form an oligomer or polymer or that all of such groups have identical sub- stituants; and each of B 1 -B 4 inclusive, independently is a moiety which imparts to the additive at least one desired characteristic; with the proviso that such plurality of groups results in at least one tetrasubstituted disiloxanyl- ene group. .44. The method of claim 37, in which said additive is a compound having the general formula, oo 5 12 :B 5 5-0-(-Si-O-)c-B 6 RI3 in which each of R 12 and R 13 independently is a monovalent 1 *.group selected from the group consisting of hydrogen, alkyl, cycloalkyl, aryl, and heterocyclic groups, each of which, except for hydrogen, is substituted or unsubsti- tuted; each of B 5 and B 6 independently is a monovalent group having a desired characteristic; and c represents an integer from 2 to "Wae& The method of claim 37, in which said additive is a compound having the general formula, -126- R17 R 1 9 R14-Si-o-(-Si-0-)d-(-Si-0-)e-Si-R21 I I R 1 6 R18 B7 R22 in which each of R 1 4 -R 22 inclusive, independently is a monovalent group selected from the group consisting of hydrogen, alkyl, cycloalkyl, aryl, and heterocyclic groups, each of which, except for hydrogen, is substituted or unsubstituted; B 7 is a monovalent group having a desired characteristic; d represents an integer from 0 to abeut and e represents an integer from 1 to abct 46, The method of claim 37, in which said additive is a compound having the general formula, R 2 5 64 5 R23-Si (-O-Si-)f-B 8 ]3 in which each of R 2 3 -R 2 5 inclusive, independently is a monovalent group selected from the group consisting of hydrogen, alkyl, cycloalkyl, aryl, and heterocyclic groups, each of which, except for hydrogen, is substituted or unsubstituted; B 8 is a monovalent group having a desired characteristic; and f represents an integer from 1 to abe kkbo

47. The method of claim 37, in which a characteristic of said moiety B is hydrophilicity.

48. The method of claim 37, in which a characteristic of said moiety B is ultraviolet radiation absorption.

49. The method of claim 37, in which a characteristic of said moiety B is degradation stabilization. o-127- t-4 4zxJ 128 The method of claim 37, in which a characteristic of said moiety B is high hydrophobicity.

51. The method of claim 37, in which a characteristic of said moiety B is a buffering capacity. 52, The method of claim 1, in which said thermoplastic composition comprises at least one thermoplastic polymer and a mixture of two or more additives.

53. The method of claim 19, in which said thermoplastic composition comprises at least one thermoplastic polymer and a mixture of two or more additives. 54, The ntthod of claim 37, in which said thermoplastic composition comprises at least one thermoplastic polymer and a mixture of o. two or more additives.

55. A method of forming a nonwoven web substantially as hereinbefore described with reference to the any one of the Examples.

56. The product of the method of any one of (laims 1 to DATED this FOURTEENTH day of FEBRUARY 1992 t. ft' Kimberly-Clark Corporation f ft Patent Attorneys for the Applicants SPRUSON FERGUSON rhk/0628E