MXPA00006565A - Melt processable poly(ethylene oxide) fibers - Google Patents

Abstract

Melt processable, flushable polymer fibers and methods of making melt processable, flushable polymer fibers are disclosed. The fibers comprise poly(ethylene oxide). Preferably, the poly(ethylene oxide) is modified by grafting polar vinyl monomers, such as poly(ethylene glycol) methacrylate and 2-hydroxyethyl methacrylate, onto poly(ethylene oxide). The modified poly(ethylene oxide) has improved melt processability and can be used to melt process poly(ethylene oxide) fibers of thinner diameters.

Description

FIBERS OF POLY (ETHYLENE OXIDE) PROCESSED WITH FUSION FIELD OF THE INVENTION The present invention is directed to polymer fibers comprising poly (ethylene oxide) compositions and to methods for making polymer fibers comprising poly (ethylene oxide) . More particularly, the present invention is directed to fibers comprising poly compositions (ethylene oxide) grafted.

BACKGROUND OF THE INVENTION Disposable personal care products such as panty liners, diapers, tampons, etc. are of great convenience. Such products provide the benefit of a one-time sanitary use and are convenient because they are easy and quick to use.

However, the disposal of many such products is a concern due to limited land fill space.

The incineration of such products is undesirable due to increasing concerns about air quality and costs and the difficulty associated with the separation of such products from the other non-incinerable discarded items. Consequently, there is a need for disposable products which can be quickly and conveniently discarded without throwing them in the land filling or without incineration.

It has been proposed to dispose of such products in private and municipal drainage systems. Ideally, such products would be disposable with water discharge and degradable in conventional drainage systems. The right products to be disposed of in drainage systems and that can be disposed of with water discharge down into the toilets are called "disposable with water discharge" here. Disposal by discharging water provides the additional benefit of providing convenient and sanitary and simple means of disposal. Personal care products must have sufficient strength under the environmental conditions in which they will be used and will be able to withstand the elevated temperature and humidity conditions encountered during use and storage but will still lose their integrity with the contact with the water in the toilet. Therefore, a water-disintegrable material which is thermally processable in fibers having mechanical integrity when dry is desirable.

Due to its unique interaction with body fluids and water, poly (ethylene oxide) (hereinafter PEO) is currently considered a component material in fibers and in disposable products with water discharge. Polyethylene oxide, - (CH2CH20) n- is a commercially available water-soluble polymer that can be produced from the ring-opening polymerization of ethylene oxide; O / \ CH2-CH2 Due to its water-soluble properties, polyethylene oxide is desirable for disposable applications with water discharge. However, there is a dilemma in using polyethylene oxide in the fiber manufacturing process. Low molecular weight polyethylene oxide resins, for example of 200,000 g / mol, have a desirable melt viscosity and melt pressure properties desirable for extrusion processing but may not be processed into fibers due to their low melt elasticities and its low melting strengths. Polyethylene oxide resins of higher molecular weights, for example greater than one million g / mol, have melt viscosities that are very high for fiber spinning processes. These properties make conventional polyethylene oxide difficult to process in fibers that use processes for conventional fiber manufacturing.

The molten polyethylene oxide and extruded d spinning plates and fiber spinning lines resist and pull and is easily broken. Polyethylene oxide resins do not form fibers using conventional fused fiber manufacturing processes. How it is used here, the fibers are defined as filaments or threads or yarn type or filament type structures with diameters of about 100 microns and less. Conventional polyethylene oxide resins can only be processed by melting on yarns with diameters in the range of several millimeters. Therefore, polyethylene oxide compositions with melt viscosities suitable for processing fibers and with higher melt elasticities and melt strengths are desired.

In the personal care industry, disposed bonded and cast fibers are desired for commercial viability and ease of disposal. The polyethylene oxide fibers have been produced by a solution setting process. However, it has not been possible to process polyethylene oxide fibers with melt using conventional fiber manufacturing techniques such as co-melted yarn. Fusion processing techniques are more desirable than solution setting because the techniques Processing with fusion are more efficient and economical. Fusion processing of the fibers is necessary for commercial viability. The polyethylene oxide compositions of the prior art can not be extruded into the melt with a suitable melt strength and elasticity to allow the attenuation of the fibers. Currently, the fibers can not be produced from conventional polyethylene oxide compositions by means of melt spinning.

Therefore, commercially available polyethylene oxide resins are not practical for extrusion with fiber melting or for personal care applications. What is required in the art, therefore, are a means for overcoming the difficulties of the processing by melting polyethylene oxide resins so that the polyethylene oxide resins can be formed into fibers for later use as components in the polyethylene oxide resins. Disposable personal care products with water discharge.

SYNTHESIS OF THE INVENTION The present invention is directed to polymer fibers but comprises polyethylene oxide compositions and methods for making polymer fibers comprising polyethylene oxide. More particularly, the present invention is directed to fibers comprising oxide compositions of grafted polyethylene. The modified polyethylene oxide compositions have improved melt processing, which allows the fibers to be pulled using conventional fiber making techniques and apparatus. The modification of the polyethylene oxide resins is achieved by grafting a polar vinyl monomer, such as a poly (ethylene glycol) methacrylate or 2-hydroxytyl methacrylate into the polyethylene oxide. The grafting is achieved by mixing the polyethylene oxide, the monomer or monomers and a free radical initiator and applying heat. The resulting grafted polyethylene oxides have improved melt processing and can be used to melt-process fibers using conventional fiber processing techniques.

To overcome the disadvantages of the prior art this invention teaches fibers comprising polyethylene oxide copolymers comprising grafted polar functional groups. Such a modification of the polyethylene oxide reduces the melt viscosity and the melt pressure of the polyethylene oxide. The modified polyethylene oxide resins can be solidified for further thermal processing into fibers or processed directly into fibers. The fibers are soluble in water and are useful as components in personal care products.

As used herein, the term "graft copolymer" means a copolymer produced by the combination of two or more chains of constitutionally or configurationally different characteristics, one of which serves as a column backbone, and at least one of the which is joined at some or some points along the column and constitutes a side chain. As used herein, the term "graft" means forming a polymer by joining chains or side species at some or some points along the column of a parent polymer. (See the work of Sperling, L.H., Introduction to the Science of Physical Polymer 1986, pages 44-47 which is hereby incorporated by reference in its entirety.) The modification of the polyethylene oxide according to the invention improves the melting properties of polyethylene oxide and allows thermal processing of the polyethylene oxide fibers. The modified polyethylene oxide compositions have increased melt strength and increased melt elasticity but nevertheless have a reduced melt viscosity. These changes make it possible to produce polyethylene oxide fibers using conventional fiber processing methods. Modifications of polyethylene oxide resins with initial molecular weights of between about 50, 000 g / mol to around 400,000 g / mol allows the oxide r polyethylene being extruded into thin fibers using conventional spinning processes with melting. Modification of polyethylene oxide resins with starting molecular weights of between about 50,000 g / mol to about 300,000 g / mol is desirable and the modification of polyethylene oxide resins with molecular weights starting between about 50,000 g / mol to about 200,000 g / mol is more desirable for fiber manufacturing purposes. The modification of the polyethylene oxide according to this invention improves the melting properties of the polyethylene oxide by allowing the modified polyethylene oxide to be melted and attenuated into fibers. Therefore, the modified polyethylene oxide can be processed into water-soluble fibers using both meltblowing and spin-bonding processes which are useful as components in liners, cloth-type outer covers, etc. in the products for the Disposable personal care with water discharge.

These and other features and advantages of the present invention will be readily apparent upon review of the following detailed description of the embodiments described.

BRIEF DESCRIPTION OF THE FIGURES Figure 1 is a graph comparing the melt viscosities of an unmodified polyethylene oxide of 200,000 g / mol molecular weight, comparative example A, against the melt viscosities of the same polyethylene oxide resin after the modification, example 2.

Figure 2 is a 13C nuclear magnetic resonance spectrum of the modified polyethylene oxide of Example 2.

Figure 3 is a nuclear magnetic resonance spectrum] H of the modified polyethylene oxide of Example 2.

DETAILED DESCRIPTION The fibers can be made using conventional processing methods of commercially available polyethylene oxide resins when modified in accordance with this invention. Polyethylene oxide resins useful for modification include, but are not limited to, polyethylene oxide resins having approximate molecular weights initially reported ranging from about 50,000 g / mol to about 8,000,000 g / mol. The higher molecular weights are desired for mechanical and physical properties Increased and low molecular weights are desired for ease of processing.

The desirable polyethylene oxide resins have molecular weights ranging from about 50,000 to about 400,000 g / mol before modification. The most desirable polyethylene oxide resins have molecular weights ranging from about 50,000 to about 300,000 g / mol, and even more desirably from about 50,000 to about 200,000 g / mol, prior to modification.

The modified polyethylene oxide compositions of the resins given above provide a balance between mechanical and physical properties and processing properties. Two polyethylene oxide resins within the desirable ranges given above are commercially available from Union Carbide Corporation and are sold under the trade designations POLYOX® WSR N-10 and POLYOX® WSR N-80. These two resins have approximate molecular weights reported, as determined by rheological measurements of around 100,000 g / mol and 200,000 g / mol respectively.

Other polyethylene oxide resins available from Union Carbide Corporation within the approximate molecular weight ranges given above can be used (see POLYOX®: Water Soluble Resins from Union Carbide Chemicals &Plastics Company, Inc., 1991 which is incorporated herein by reference in its entirety) as well as other polyethylene oxide resins available from other suppliers and manufacturers. Both the polyethylene oxide powder and the polyethylene oxide pellets can be used in this invention since the physical form of the polyethylene oxide does not affect its behavior in the molten state for the grafting reactions. This invention has been demonstrated by the use of several of the aforementioned polyethylene oxide resins in powder form as supplied by Union Carbide and pelletized resins as supplied by Planet Polymer Technologies of San Diego, California. The initial polyethylene oxide resin and the modified polyethylene oxide compositions may optionally contain various additives such as plasticizers, processing aids, rheology modifiers, antioxidants, ultraviolet stabilizers, pigments, dye, slip additives, antiblock agents, etc.

A variety of polar vinyl monomers may be useful in the practice of this invention. The monomer or monomers as used herein include monomers, oligomers, polymers, mixtures of monomers, oligomers and / or polymers, and any other reactive chemical species which are capable of covalent attachment to the parent polymer, polyethylene oxide. Ethylene-unsaturated monomers containing a polar functional group, such as hydroxyl, carboxyl, amino, carbonyl, halo, thiol, sulphonic, sulfonate, etc., are suitable for this invention and are desirable. The desired ethylenically unsaturated monomers include acrylates and methacrylates. Particularly desired ethylenically unsaturated monomers containing a polar functional group are 2-hydroxytyl methacrylate (hereinafter HEMA) and poly (ethylene glycol) methacrylates (hereinafter PEG-MA). A particularly desired poly (ethylene glycol) methacrylate is poly (ethylene glycol) ethyl ether methacrylate. However, it is expected that a wide range of polar vinyl monomers will be capable of imparting the same effects as HEMA and PEG-MA to polyethylene oxide and that they are effective monomers for grafting. The amount of polar vinyl monomer in relation to the amount of polyethylene oxide can vary from about 0.1 to about 20 percent by weight of the monomer to the weight of the polyethylene oxide. Desirably, the amount of monomer must exceed 0.1 percent by weight in order to sufficiently improve the processing of the polyethylene oxide. More desirably, the amount of the monomer should be at the lower end of the range described above, from 0.1 to 20 percent by weight, in order to decrease costs. A range of graft levels is demonstrated in the examples. Typically, the monomer addition levels were between 2.5 to 15 percent by weight of the base polyethylene oxide resin.

This invention has been demonstrated in the following examples by the use of PEG-MA and HEMA as the polar vinyl monomers. Both PEG-MA and HEMA were supplied by Aldrich Chemical Company. The HEMA used in the examples was designated Aldrich catalog number 12,863-5 and the PEG-MA was designated Aldrich catalog number 40,954-5. The PEG-MA was a poly (ethylene glycol) ethyl ether methacrylate having a number average molecular weight of approximately 246 g / mol. PEG-MA with a number average molecular weight higher or lower than 246 g / mol are also applicable to this invention. The molecular weight of PEG-MA can vary up to 50,000 g / mol. However, lower molecular weights are desirable for faster graft reaction rates. The desirable range of the molecular weight of the monomers is from 246 to 5,000 g / mol and the most desirable range is from 246 to 2,000 g / mol. Again it is expected that a wide range of polar vinyl monomers as well as a broad range of molecular weights of the monomers will be capable of imparting effects similar to polyethylene oxide resins and will be effective monomers for grafting and modification purposes.

A variety of primers can be used in the practice of the invention. If the graft is achieved by the application of heat, as in a reactive and extrusion process, it is desirable that the initiator generates free radicals with the application of heat. Such initiators are generally referred to as thermal initiators. In order for the initiator function as a useful source of radicals for grafting, the initiator must be commercial and readily available, must be stable to environmental or refrigerated conditions and generate radicals at reactive extrusion temperatures.

Compounds containing a 0-0, S-S, or N = N bond can be used as thermal initiators. Compounds containing O-O bonds, such as peroxides, are commonly used as initiators for polymerization. Such commonly used peroxide initiators include alkyl, dialkyl, diaryl and arylalkyl peroxides such as cumyl peroxide, t-butyl peroxide, di-t-butyl peroxide, dicumyl peroxide, cumyl butyl peroxide, 1,1-diol. t-butyl peroxide-3,5,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexin-3 and bis (at-butylperoxyisopropylbenzene); acyl peroxides such as acetyl peroxides and benzoyl peroxides; hydroperoxides such as cumyl hydroperoxide, t-butyl hydroperoxide, t-methane hydroperoxide, hydroperoxide sinane and hydroperoxide eumenum; peresters or peroxyesters such as t-butyl peroxypivalate, t-butyl peroctate, t-butyl perbenzoate, 2,5-dimethylhexyl-2,5-di (perbenzoate) and t-butyl di (perftalate); alkylsulfonyl peroxides; dialkyl peroxymonocarbonates; dialkyl peroxydicarbonate; diperoxyketals; acetone peroxides such as cycloexanone peroxide and methyl ethyl ketone peroxide. Additionally, azo compounds such as 2,2'- Azobisisobudionitrile, such as AIBN, 2, 2'-azobis (2,4-dimethylpentanenitrile) and 1,1''-azobis (cyclohexanecarbonitrile) can be used as the initiator. This invention has been demonstrated in the following examples by the use of a liquid organic peroxide initiator available from Elf Atochem North America, Inc. of 200 Market Street, Philadelphia, Pennsylvania, sold under the trade designation LUPERSOL®101. Said LUPERSOL®101 is a free radical initiator and comprises 2,5-dimethyl-2,5-di (t-butylperoxy) hexane. Other initiators and other classes of LUPERSOL® initiators can also be used such as LUPERSOL®130.

A variety of the recipients of the action may be useful in the practice of this invention. The modification of the PEO can be carried out in any container provided that the necessary mixing of the polyethylene oxide, the monomer and the initiator is achieved and that sufficient thermal energy is provided to effect the grafting. Desirably, such containers include the suitable mixing device, such as Bradender Plasticorders, Haake extruders, single or multiple screw extruders or any other mechanical devices which can be used to mix, combine, process or manufacture polymers. In the examples that follow, the reaction device is a twin counter-rotating screw extruder, such as a Haake extruder available from Haake, 53 West Century Road, Paramus, New Jersey 07652 or an extruder. of cogromator twin screw, such as a twin screw combination extruder ZSK-30 manufactured by Werner _ Pfleiderer Corporation of Ramsey, New Jersey. It should be noted that a variety of extruders can be used to modify the polyethylene oxide and to produce fibers according to this invention whenever mixing and heating occur.

The ZSK-30 extruder that allows multiple supply, has ventilation ports and is capable of producing modified PEO at a rate of up to 50 pounds per hour. If a higher modified PEO production rate is desired, a commercial scale ZSK-58 extruder manufactured by Werner & Plfleiderer. The ZSK-30 extruder has a pair of co-rotating screws arranged in parallel with the center-to-center distance between the axes of the two 26.2 mm screws. The nominal screw diameters are 30mm. The actual external diameters of the screws are 30mm and the inner screw diameters are 21.3mm. The thread depth is 4.7mm. The lengths of the screws are 1328mm and the length of the total processing section was 1338mm. This ZSK-30 extruder had 14 processing barrels, which are numbered consecutively from 1 to 14 from the barrel of supply to the matrix for the purposes of this description. The first barrel, barrel number 1 received the PEO and was not heated but cooled by water. The matrix used to extrude the modified PEO yarns has four 3mm openings diameter which are separated by 7mm. The modified PEO yarns were extruded in an air-cooled band and then pelletized. The extruded PEO cast strands were air cooled on a 20-foot fan-cooled conveyor belt.

Another suitable extruder as the reaction device includes a Haake extruder. The modified PEO compositions of Examples 31, 32 and 33 suitable for the purposes of fiber manufacture were modified by a reactive extrusion process using a Haake extruder. The Haake extruder that was used was a twin counter-rotating screw extruder that contained a pair of taper counter-rotating screws made to order. The Haake extruder had a length of 300mm. Each conical screw had a diameter of 30mm in the supply port and a diameter of 20mm in the matrix, the monomer and the initiator were added to the supply throat of the Haake extruder contemporaneously with the polyethylene oxide resin.

The Haake extruder comprised six sections as follows: Section 1 comprised of a double-stage forward pumping section that has a large screw tilt and a high helix angle. Section 2 comprised a double-section forward pumping section that has a smaller screw tilt than section 1. Section 3 comprised a double-section forward pumping section that had a screw pitch smaller than that of section 2. Section 4 comprised a double-section, notched, reverse pumping section where a full length was notched. Section 5 comprised a double-section, forward pumping section that contained two complete sections. And section 6 comprised a double-legged forward pumping section that had an intermediate screw pitch between that of section 1 and section 2.

COMPARATIVE EXAMPLE A A PEO resin having a molecular weight of about 200,000 g / mol was processed through a Haake extruder under conditions similar to that of the modified examples of the invention for comparative purposes and to demonstrate that the PEO resins were unmodified and conventional can not be processed with fiber fusion. The unmodified PEO resin of molecular weight of 200,000 g / mol which was used for this comparative example was obtained from Planet Polymer Technologies. The resin obtained from Planet Polymer Technologies was in pellet form and was composed of POLYOX® WSR N-80 PEO resin manufactured by Union Carbide Corp.

For processing, the temperatures of the extruder barrel were set at 170, 180 and 180 ° C for the zones of first, second and third heating, respectively, and 190 ° C for the matrix. The screw speed was set at 150 revolutions per minute. The polyethylene oxide resin was supplied to the extruder at a production of about 5 pounds per hour. A monomer or initiator was not added to the PEO resin of Comparative Example A. The unmodified PEO was extruded under the above-mentioned conditions, cooled in air and pelleted for later use. Attempts have been made to melt process the unmodified PEO of Comparative Example A into fibers. Because the molten PEO of Comparative Example A had a very low melt elasticity and a very low melt strength to allow attenuation of the PEO melt, the fibers could not be melt processed using conventional fiber spinning techniques, such like the Lurgi gun, the initiating gun and the free fall. The melt of extruded PEO from the spinning plate came out easily and did not allow the unmodified PEO to be pulled into fibers. Only threads of about 1 to 2 mm in diameter could be produced from the unmodified PEO of Comparative Example A.

COMPARATIVE EXAMPLE B A PEO resin having a molecular weight of about 100,000 g / mol was processed through a Haake extruder under the same conditions as in comparative example A. The PEO resin of molecular weight of 100,000 g / mol which was used for this comparative example B was obtained from Planet Polymer Technologies and was in a pellet form and was composed of the POLYOX® WSR N-10 resin manufactured by Union Carbide Corp. Attempts were also made to melt process the unmodified PEO comparative example B in fibers. Fibers with diameters of less than about 100 microns could not be processed by melting PEO resin of 100,000 g / mol molecular weight using conventional fiber spinning techniques. Even then the melt could only be pulled very slowly and the melt was easily broken, making the commercial production of the polyethylene oxide fibers impractical. Therefore, comparative examples A and B demonstrated that the unmodified PEO resins of the prior art can not be processed with fiber fusion.

EXAMPLES Polyethylene oxide resin POLYOX® WSR N-10 of 100,000 g / mol was supplied to a Haake extruder at 5.3 pounds per hour along with 0.53 pounds per hour of PEG-MA monomer and 0.026 pounds per hour of radical initiator. free LUPERSOL® 101, from Example 3 of Table 1. POLYOX® WSR N-80 polyethylene oxide of 200,000 g / mol was modified in the same manner with the same monomer and initiator at the same relative amounts, example 2 in Table 1. When the monomer and initiator were added to the PEO base resins during extrusion, the melt elasticities and the melting strengths of the PEO resins were visibly improved. These modified PEO compositions were collected in bulk and then ground into a powder for further processing into fibers.

The melt viscosities of the PEO resins were observed as they were essentially reduced by the modification with the monomer and the initiator. The melt viscosity of the polyethylene oxide resins of 200,000 g / mol unmodified and modified were measured at various cutting rates and are presented in figure 1. The melt viscosity of the unmodified PEO resin, WSR N- 80 was 319 Pascals * seconds (Pa * S hereafter) to 1000 seconds "1. In contrast, the melt viscosity of the same PEO resin modified by the addition of monomer and initiator, example 2, was reduced to 74 Pa * S at the same cutoff rate.

The melt viscosities of comparative example A and example 2 were determined by means of melt rheology tests carried out on a Goettfert Rheograph 2003 capillary rheometer. The rheometer was operated with a matrix of 30 / lmm length / diameter at 195 ° C. The apparent melt viscosities measured in Pa * S were determined at apparent cut-off rates of 50, 100, 200, 500, 1000 and 2000 seconds "1 in order to develop rheology curves for each of the polyethylene oxide compositions. The rheology curves of the two respective PEO compositions are presented in Figure 1. Over the entire range of the cut rates tested, the modified PEO exhibited lower apparent viscosities than the PEO from which it was modified.

The modification by grafting the monomer into the polyethylene oxide brought a 77 percent drop in the melt viscosity. The reduced viscosity brought by the PEO modification makes PEO fiber yarn possible. The fibers of very small diameters, in the range of 20-30 micrometers, were able to be continuously pulled from the modified PEO resins. Fibers within this range of diameters are useful for making non-woven fabrics bonded with yarn. PEO fibers and fabrics are disposable with water discharge and dispersible in water and can be used as components in disposable personal care products.

When the addition of the monomer and the initiator was stopped during the extrusion process, the properties of the polyethylene oxide resins reverted to their previous values and the fibers could not be pulled out of the unmodified PEO melt. This shows that the modification occurs and improves the PEO properties which is critical for fiber manufacture and commercial viability.

Other examples of the modified PEO resins were produced to further demonstrate the invention. These other examples of the polyethylene oxide resins were produced by varying: the molecular weights, of 100,000 and 200,000 g / mol, and the PEO suppliers , Union Carbide and Planet Polymer Technology, Inc. (a combiner, hereinafter abbreviated PPT); the monomers, 2-hydroxytyl methacrylate and the poly (ethylene glycol) ethyl ether methacrylate described above and the amount of monomers; the amount of the initiator of LUPERSÓL® 101 and the extruder. The various parameters used in the various examples are listed in Table 1 given below. The percentages by weight of the components used in the examples were calculated in relation to the weight of the base resin, polyethylene oxide, unless indicated otherwise.

TABLE 1 Components and Process Conditions of the Examples Examples 1, 2 and 3 were processed in the Haake extruder under similar conditions as described in the comparative examples given above. The exact extruder design, temperatures and screw speed were used. However, examples 1, 2 and 3 included the addition of the monomer and the initiator to the PEO resin in order to modify said polyethylene oxide resin. The listed amounts of the monomer and the initiator were added to the feed throat of the Haake extruder contemporaneously with the polyethylene oxide resin.

Examples 4, 5, 6 and 7 were modified in the ZSK-30 extruder detailed above. The fourteen heated barrels of the ZSK-30 extruder consist of seven heating zones. For the modification of examples 4-7, the seven zones of the extruder ZSK-30 were all set at 180 ° C and the screw speed was set at 300 rpm. The respective monomer, HEMA or PEG-MA as listed in table 1, was injected into barrel number 4 and the initiator was injected into barrel number 5. Both the monomer and the initiator were injected through an injector from pressurized nozzle to cup listed. The order in which the polyethylene oxide, the monomer and the initiator were added to the polyethylene oxide, is not critical. The initiator and the monomer can be added at the same time or in reverse order. It should be noted that the order used in the examples is preferred.

Although the invention has been demonstrated by the examples, it is understood that the polyethylene oxide, the polar vinyl monomer, the initiator and the conditions may vary depending on the type of modified polyethylene oxide composition and the desired properties.

Attempts were made to melt-process fibers of the polyethylene oxide compositions of Examples 1, 2 and 3 using conventional melt processing techniques. The modified PEO compositions of Examples 1, 2 and 3 were processable with fiber melt by means of a research scale spinning bonding process, in contrast to the unmodified PEO compositions of Comparative Examples A and B which can not be extruded in a melt with a suitable melt strength and an elasticity to process them into fibers. The melt processing of the modified PEO resins was demonstrated by means of a conventional spinning bonding process on an experimental spinning line comprising a single screw extruder, a melt metering pump and a spin plate. The spinning process was used to spin the fibers but was not used to join the fibers. Free-falling fibers and fibers pulled by hand and by means of an initiating gun on a fiber spinning line were produced from the modified PEO composition of Example 1. Free-falling fibers and fibers pulled by means of a Lurgi gun and by means of an initiating gun on a fiber spinning line were produced from the modified PEO composition of example 2. Free falling fibers and fibers pulled by means of an initiating gun on a fiber spinning line were produced from the modified PEO composition of Example 3.

Although no attempts have been made to process the fibers of the modified PEO compositions of Examples 4, 5, 6 and 7, the modified PEO compositions are expected to be melt processable into fibers. The appearance of the modified and extruded PEO compositions of Examples 4, 5, 6 and 7 was similar to the appearance of Examples 1, 2 and 3 exhibiting lower viscosities and a more tacky material. These reduced melt viscosities make it possible to spin fibers of the modified PEO compositions and are particularly advantageous for the manufacture of commercial fibers especially when methods requiring melt processing are used.

Some of the modified PEO compositions were converted to meltblown fibers. The fibers retained the same solubility in beneficial water as the unmodified PEO. This property is particularly desired for disposable applications with water discharge. The fibers produced by the spinning process were also soluble in water and are therefore easily disposable with water discharge.

Physical test and characterization of the modified PEO and the fibers produced from the modified PEO.

Stress tests were carried out on fibers produced from the modified PEO compositions of examples 1, 2 and 3. The tests were carried out using a Sintech l / D voltage tester available from MTS Systems Corp., of Machesny Park, Illinois. The diameter of the fibers was measured before the test and then the fiber was tested with a one-inch grip separation and a crosshead speed of 500 mm / min. The diameters and tensile properties of the fibers produced from the modified PEO resins of Examples 1, 2 and 3 were measured and reported in Table 2 given below. Fibers made from PEO of 200,000 g / mol were significantly more ductile than those made from 100,000 g / mol. For fibers made from the same molecular weight PEO base resin, additional levels of higher PEG-MA, for example, 10 percent by weight led to a significantly increased ductilide of the fibers. The PE fibers pulled with Lurgi gun at 10 percent PEG-M addition had a peak stress of 7.2 MPa and 648 percent d elongation at break. These tensile property values are extremely favorable for fibers derived from PEO considering that said unmodified PEO is very brittle in nature.

TABLE 2 Stress Properties of the Fibers Produced from Examples I 2 and 3 Chemical Characterization of GPC analysis The number average molecular weight (Mn), the weight average molecular weight (Mw), and the z-average molecular weight (Mz) of Comparative Examples A and B and Examples 1, 2 and 3 were determined by gel permeation chromatography (hereinafter GPC). The GPC chromatography analysis was conducted by the American Polymer Standards Corporation of Mentor, Ohio. From these measurements, the polydispersity indices (Mw / Mn) of the respective examples were calculated. The various molecular weights and polydispersity of the examples are reported in Table 3 given below.

NMR analysis The modified PEO composition of examples 1, 2 and 3 was analyzed by NMR spectroscopy. The spectrum 13C and JH NMR of Example 2 are presented as Figures 2 and 3, respectively. The results of this analysis confirmed that the PEG-MA units contained modified PEO.

The grafting levels of the modified PEO compositions of Examples 1, 2 and 3 as measured by NMR analysis are reported as percentages by weight of monomer by weight of PEO base resin and grafted to the PEO resin and are reported in table 3. The percentages of the Ungrafted monomer of examples 1, 2 and 3 are reported similarly in Table 3.

TABLE 3 Chemical properties of comparative examples A and B and modified PEO compositions of examples 1, 2 and 3 The molecular weights of the modified PEO examples are significantly different from the corresponding unmodified PEO resin. Significant reductions in molecular weights and polydispersity indices were observed after a reactive extrusion of the PEO with the monomer and the initiator compared to the extruded and unmodified PEO of the comparative examples. The weight average molecular weight of the PEO N-80 dropped from 148,100 g / mol for the unmodified but similarly processed PEO N-80 of comparative example A to 97, 200 g / mol for PEO N-80 5 percent grafted from example 1 and 109,300 g / mol for PEO N-80 10 percent grafted from example 2. Similarly, the weight average molecular weight of PEO N-10 fell from 115,900 g / mol for the unmodified PEO N-10 of comparative example B at 90,600 g / mol for the grafted PEO 10 percent N-10 of example 3. Therefore, the modification of the PEO resins produced a significant reduction in the average molecular weight weight. However, the number average molecular weight was not greatly affected by the modification, therefore, there was a significant decrease in the polydispersity index and therefore, a narrower molecular weight distribution.

The fundamental changes in the PEO brought about by the chemical graft have profound and unexpected effects on the physical properties and melt processing of the PEO as demonstrated here and discussed above. The weight distributions Closer molecular compositions of the modified PEO resulted in improved solid and molten state properties. Even though it is not desired to be bound by the following theory, it is believed that during the extrusion-reactive process of the PEO resin, the initiator started three competitive actions: 1) the grafting of the vinyl monomer onto the PEO, 2) the degradation of the PEO, and 3) the cross-linking of the PEO. A novel method to achieve the improved properties has been developed and which is contrary to the traditional methodology and thought and the development of the polymer. The method degrades the polymer and shorter chains as opposed to only increasing the molecular weight by grafting and cross linking. The resulting modified PEO compositions have improved melt strength and melt elasticity, overcoming the inherent deficiencies of both the low molecular weight PEO and the higher molecular weight PEO.

In the case of grafting, the presence of a sufficient amount of monomer or monomers as demonstrated in the examples given herein, the crosslinking is negligible and does not adversely affect the properties of the modified PEO. The cross-linking reaction only predominates when there is little or no monomer present during the modification of the PEO resin. Therefore, the graft and degradation reactions of the PEO must predominate and are desired to produce the PEO compositions suitable for the purposes of film and fiber manufacture.

The modified PEO resins are observed to have improved melt strength and improved melt elasticities, overcoming the inherent deficiencies of both the low molecular weight and high molecular weight PEO resins. These improved melt properties also allow the modified PEO to be processed into useful fibers with diameters of less than 100 microns using conventional fiber pulling techniques.

The present invention has been illustrated in great detail by the specific examples given above. It should be understood that these examples are illustrative embodiments and that this invention is not limited by any of the examples or details in the description. Those skilled in the art will recognize that the present invention is capable of many modifications and variations without departing from the scope of the invention. Therefore, the detailed description of the examples is intended to be illustrative and does not mean that they limit in any way the scope of the invention as set forth in the following clauses. Rather, the appended claims herein should be broadly considered within the scope and spirit of the invention.

Claims (20)

1. A fiber comprising poly (ethylene oxide) that is soluble in water and processable with melt.

2. The fiber as claimed in clause 1 characterized in that the fiber diameter has an average diameter of no more than about 100 microns.

3. The fiber as claimed in clause 1 characterized in that the poly (ethylene oxide) has a sufficient melt strength and a sufficient melt elasticity for spinning with fiber melt.

4. The fiber as claimed in clause 3 characterized in that the poly (ethylene oxide) has an apparent viscosity of less than 200 Pascals * seconds at cut-off rates of not less than 100 seconds'1 and not greater than 1,000 seconds' 1.

5. The fiber as claimed in clause 1 characterized in that the poly (ethylene oxide) has a molecular weight in the range of about 50,000 g / mol to about 400,000 g / mol.

6. The fiber as claimed in clause 3 characterized in that the fiber consists essentially of poly (ethylene oxide).

7. A fiber comprising a modified poly (ethylene oxide).

8. The fiber as claimed in clause 7 characterized in that the modified poly (ethylene oxide) is in turn modified from a poly (ethylene oxide) having an initial molecular weight before modification within the range of about 50,000 g / mol to around 400,000 g / mol.

9. The fiber as claimed in clause 8 characterized in that the modified poly (ethylene oxide) is in turn modified from poly (ethylene oxide) having an initial molecular weight before modification within the range of about 50,000 g / mol to around 200,000 g / mol.

10. The fiber as claimed in clause 7 characterized in that the modified poly (ethylene oxide) is modified by the addition of an initiator.

11. The fiber as claimed in clause 7 characterized in that the modified poly (ethylene oxide) is modified by the addition of a monomer and an initiator.

12. The fiber as claimed in clause 11 characterized in that the monomer is a polar vinyl monomer.

13. The fiber as claimed in clause 12 characterized in that the polar vinyl monomer is selected from the group consisting of poly (ethylene glycol) methacrylates and 2-hydroxytyl methacrylate.

14. The fiber as claimed in clause 13 characterized in that the polar vinyl monomer is a poly (ethylene glycol) ethyl ether methacrylate and has an average molecular weight of no more than about 5,000 g / mol.

15. The fiber as claimed in clause 11, characterized in that the monomer is added within the range of about 0.1 percent by weight to about 20 percent by weight relative to the weight of the poly (ethylene oxide).

16. The fiber as claimed in clause 7 characterized in that the modified poly (ethylene oxide) is a grafted poly (ethylene oxide).

17. A method for processing poly (ethylene oxide) fibers comprising the steps of: a) adding a poly (ethylene oxide), a monomer and an initiator to a reaction vessel; b) mixing the poly (ethylene oxide), the monomer and the initiator under conditions sufficient to graft the polar vinyl monomer onto the poly (ethylene oxide); Y c) pull the poly (ethylene oxide) fibers.

18. The method as claimed in clause 17 characterized in that the monomer is a polar vinyl monomer.

19. The method as claimed in clause 17 characterized in that the polar vinyl monomer is selected from a group consisting of poly (ethylene glycol) methacrylates and 2-hydroxytyl methacrylate.

20. A fiber produced by the method as claimed in clause 17.