WO2001000731A1

WO2001000731A1 - Compositions comprising a blend of poly(ethylene oxide) and a grafted polyolefin and method of making the same

Info

Publication number: WO2001000731A1
Application number: PCT/US2000/017787
Authority: WO
Inventors: James Hongxue Wang; David Michael Schertz
Original assignee: Kimberly-Clark Worldwide, Inc.
Priority date: 1999-06-29
Filing date: 2000-06-28
Publication date: 2001-01-04
Also published as: AU5897000A

Abstract

Thermoplastic, selectively water-responsive compositions comprising a blend of a poly(ethylene oxide) that may be grafted or ungrafted and a grafted polyolefin are provided. Desirably, the polyolefin is grafted with a compatabilizing monomer. The compatabilizing monomer can be any reactive species capable of covalently bonding with the polyolefin and includes monomers, oligomers and polymer or macromers having double bonds, such as α, β-ethylenically unsaturated species, capable of covalently bonding with the polyolefin to provide a grafted polyolefin. Desirably, the monomer is a polar, vinyl monomer such a poly(ethylene glycol) methacrylate. The water-responsive compositions can be water dispersible, water disintegratable or water weakenable depending on the relative amounts of poly(ethylene oxide) and grafted polyolefin incorporated in the blend. The water responsiveness of the article can be varied by modifying the polyolefin and decreasing the content of polyolefin in the blend from about 55 weight percent down to about 1 weight percent.

Description

COMPOSITIONS COMPRISING A BLEND OF

POLY(ETHYLENE OXIDE) AND A GRAFTED POLYOLEFIN

AND METHOD OF MAKING THE SAME

FIELD OF THE INVENTION The present invention relates to water-responsive compositions compπsing a thermoplastic blend of hydrophilic and hydrophobic polymers. More particularly, the pre sent invention relates to water-responsive articles made from a composition comprising a blend of poly(ethylene oxide) and a grafted polyolefin and includes articles comprising such compositions and methods of making such compositions.

BACKGROUND OF THE INVENTION

Personal care products, such as diapers, sanitary napkins, adult incontinence garments, and the like are generally constructed from a number of different components an d materials. Such articles usually have some portion, usually th e backing layer, constructed of a liquid repellent film material. The liquid repellent film commonly used includes plastic materials such as a polyethylene film or copolymers of ethylene and other polar and nonpolar monomers. The purpose of the liquid repellent layer is to minimize or prevent absorbed liquid that may, during use, exude from the absorbent and soil the user o r adjacent clothing. The liquid repellent film also has the advantage of allowing greater utilization of the absorbent capacity of the product.

Although such products are relatively inexpensive, sanitary and easy to use, disposal of a soiled product is not without its problems. Typically, the soiled products are disposed in a solid waste receptacle. This adds to solid waste disposal costs and presents health risks to persons who may come in contact with the soiled product. An ideal disposal alternative would be to use municipal sewage treatment and private residential septic systems by flushing the soiled product in a toilet. Products suited for disposal in sewage systems are termed "flushable." While flushing such articles would be convenient, the liquid repellent material normally does not disintegrate in water. This tends to plug toilets and sewer pipes, frequently necessitating a visit from the plumber. At the municipal sewage treatment plant the liquid repellent material may disrupt operations by plugging screens and causing sewage disposal problems. It therefore becomes necessary, although undesirable, to separate the barrier film material from the absorbent article prior to flushing.

In addition to the article itself, typically the packaging in which the disposable article is distributed is also made from a water-resistant material. Water resistivity is necessary to prevent the degradation of the packaging from environmental conditions and to protect the disposable articles therein. Although this packaging may be safely stored with other refuse for commercial disposal, and especially in the case of individual packaging of the products, it would be more convenient to dispose of the packaging in the toilet with the discarded disposable article. However, where such packaging is composed of a water-resistant material, the aforementioned problems persist.

In an effort to overcome these deficiencies, hydrophilic materials can be made, to a degree, hydrophobic. To make a hydrophilic material partially hydrophobic, the material has to b e treated with a hydrophobic material to impart the desired water- resistant properties to the material. The problem with this method is that the material used to impart water repellency t o the hydrophilic material may further interfere with disintegration of the article when flushed, negating any advantage of using a hydrophilic material.

Alternatively, a hydrophobic material can be made, to a degree, hydrophilic. This typically has been achieved by modifying a water resistant material, such as polyethylene, with a hydrophilic monomer such as (meth)acrylic acids, (meth)acrylate esters, hydroxyalkyl (meth)acrylate, polyethylene glycol, and glycidal methacrylate thereby making a hydrophobic material more hydrophilic. One consideration when modifying the hydrophobic property of the barrier film by blending a hydrophobic polymer with a hydrophilic polymer, is the compatibility of the two polymers. If the two polymers are completely non-compatible, then articles comprising the blend of non-compatible polymers have poor mechanical and aesthetic compatibilities. Generally, blends of polyolefin with poly(ethylene oxide) are very poor.

SUMMARY OF THE INVENTION

Briefly, the present invention relates to water-responsive articles and compositions comprising a blend of polyolefin an d poly(ethylene oxide). In one embodiment, the water responsive composition comprises a blend having from about 1 weight percent to about 55 weight percent of a grafted polyolefin and from about 45 weight percent to about 99 weight percent o f poly (ethylene oxide). The polyolefin can be grafted with fro m about 1 weight percent to about 20 weight percent of a compatibilizing monomer, desirably a polar vinyl monomer, such as poly(ethylene glycol) methacrylate.

In another desirable embodiment, the blend is water dispersible and comprises from about 1 weight percent to about 35 weight percent of grafted polyolefin, such as polyethylene o r polypropylene, and from about 65 weight percent to about 9 9 weight percent of poly(ethylene oxide).

As used herein, the term "water responsive" includes article materials that are water dispersible, water disintegratable and water weakenable. "Water dispersible" is used herein to describe a 5 mil (0.005 of an inch) film that, under the water-responsive test described below, dissolves or breaks into pieces smaller than a 20-mesh screen. "Water disintegratable" describes a 5-mil film that, under the water-responsive test, breaks into multiple pieces after 2 minutes with some of the pieces caught by a 20-mesh screen.

"Water weakenable" describes a 5 mil film that, under the water-response test, remains in tact but loses rigidity and becomes drapable, i.e., will bend without an external force applied to the film when it is held by one corner at a substantially horizontal position.

Another aspect of the invention provides for a method o f making the grafted polyolefin and poly(ethylene oxide) blend compositions. The method includes blending under melt conditions specified amounts of either a modified or a n unmodified polyolefin with an ethylene oxide polymer. When the polyolefin has been modified by having grafted thereto a compatibilizing monomer the blend will have from about 1 weight percent to about 55 weight percent of the modified polyolefin with from about 45 weight percent to about 99 weight percent of poly(ethylene oxide).

It is an object of the invention to provide a water- responsive composition comprising a polyolefin an d poly(ethylene oxide).

It is another object of the invention to provide a water-responsive thermoplastic blend that can be conveniently and economically processed on existing standard manufacturing equipment, in a conventional manner known in the art.

Another object of the invention is to provide water- responsive, thermoplastic compositions that will be attractive, economical and capable of being flushed without the adverse effects presently attributed to such products.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a scanning electron photomicrograph of a film made from a blend of 70 weight of percent poly(ethylene oxide) and 30 weight percent of ungrafted polyethylene.

Figure 2 is a scanning electron photomicrograph, at the same magnification as Figure 1, of a film made of a blend of 7 0 weight percent poly(ethylene oxide) and 30 weight percent of a grafted polyethylene.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention resides in the discovery that water- responsive, thermoplastic articles can be made from a compositional blend comprising a polyolefin and poly(ethylene oxide). In accordance with the invention, the water responsiveness of the compositions and articles therefrom can b e varied by modifying the polyolefin or polyolefins, for example by grafting the polyolefin or mixture of polyolefins. The water responsiveness of the compositions and articles therefrom c an also be varied by varying the ratio of polyolefin(s) or modified polyolefin(s) in the blend relative to amount of poly(ethylene oxide) present in the blend. The polyolefin component of the compositions of the present invention may comprise a mixture of polyolefins. Desirably, the polyolefins are thermoplastic to facilitate processing. Saturated ethylene polymers are useful as a polyolefin component in the compositions of present invention . As used herein, the term "saturated" refers to polymers, which are fully saturated, but also includes polymers containing up t o about 5% unsaturation. Suggested polyolefins include, but are not limited to, homopolymers and copolymers of ethylene and polypropylene that are essentially linear in structure. Suggested homopolymers of ethylene include, but are not limited to, those prepared under either low pressure, i.e., linear low density o r high density polyethylene, or high pressure, i.e., branched or low density polyethylene. High-density polyethylenes are typically characterized by a density that is about equal to or greater than 0.94 grams per cubic centimeter (g/cc). High-density polyethylenes useful as the polyolefin resin in the pre sent invention have a density ranging from about 0.94 g/cc to about 0.97 g/cc.

Desirably, the polyolefins can have a melt index, a s measured at 2.16 kg and 190°C, ranging from about 0.01 decigrams per minute (dg/min) to 100 dg/min. More desirably, the polyolefins have a melt index of 0.01 dg/min to about 5 0 dg/min and more desirably of 0.05 dg/min to 25 dg/min. Low- density polyethylene has a density of less than 0.94 g/cc and is usually in the range of 0.91 g/cc to about 0.93 g/cc. Low-density polyethylene has a melt index ranging from about 0.05 dg/min t o about 100 dg/min and desirably from 0.05 dg/min to about 2 0 dg/min. Ultra low-density polyethylene can also be used as th e polyolefin in accordance with the present invention. Generally, ultra low-density polyethylene has a density of less than 0.90g/cc. Generally, polypropylene has a semi-crystalline structure having a molecular weight of about 40,000 or more, a density o f about 0.90 g/cc, a melting point of about 168°C to about 171 °C for isotactic polypropylene and a tensile strength of about 5000 psi. Polypropylene can also have other tacticities including syndiotactic and atactic. Mixtures of polyethylenes an d polypropylenes and other known polyolefins can be used as the polyolefin component of the compositions of the pre sent invention. The above polyolefins can be manufactured by using the well-known multiple-site, Ziegler-Natta catalysts or the more recent single-site, metallocene catalysts. The metallocene- catalyzed polyolefins have better-controlled polymer microstructures than polyolefins manufactured using Ziegler- Natta catalysts, including narrower molecular weight distribution, well-controlled chemical composition distribution, comonomer sequence length distribution, and stereoregularity. Metallocene catalysts are known to polymerize propylene into atactic, isotactic, syndiotactic, and isotactic-atactic stereoblock copolymers .

Suggested copolymers of ethylene that are useful as a polyolefin in the present invention may include copolymers o f ethylene with one or more additional polymerizable, unsaturated monomers. Examples of such copolymers include, but are n o t limited to, copolymers of ethylene and -olefins (such a s propylene, butene, hexene or octene) including linear low density polyethylene; copolymers of ethylene and vinyl esters of linear o r branched carboxylic acids having 1 to 24 carbon atoms such a s ethylene-vinyl acetate copolymers; and copolymers of ethylene and acrylic or methacrylic esters of linear, branched or cyclic alkanols having 1 to 28 carbon atoms. Examples of these latter copolymers include ethylene-alkyl (meth)acrylate copolymers, such as ethylene-methyl acrylate copolymers.

In one desirable embodiment, the polyolefin is a graft copolymer. The polyolefin may be grafted prior to or during the combination with the poly (ethylene oxide) component of the compositions of the present invention. Desirably, the polyolefin is grafted with 0.1 to 20 weight percent of one or more compatabiuzing monomers relative to the weight of polyolefin prior to grafting. More desirably, the compatabiuzing monomer is a polar vinyl monomer, oligomer, macromonomer or polymer. As used herein, the term "monomer" includes reactive species capable of covalently bonding with the polyolefin and includes monomers, oligomers and polymers or macromers having double bonds capable of covalently bonding with the polyolefin t o provide a grafted polyolefin. Desirably, the grafted polyolefins have a melt index greater than 0.005 dg/min to less than about 100 dg/min.

Surprisingly, water-responsiveness for the compositions an d articles comprising the compositions can be varied by modifying the polyolefin and by varying the amount of the polyolefin in the composition. The polyolefin is modified by grafted one or more compatabiuzing monomers with the polyolefin. Non-limiting examples of suitable compatabiuzing monomers include 2 - hydroxyethyl methacrylate and poly(ethylene glycol) ethyl ether methacrylate. Grafting of compatabiuzing monomers is described in greater detail in the commonly assigned U.S. patent application entitled "METHOD OF MAKING POLYOLEFINS HAVING GREATER THAN 5 PERCENT 2-HYDROXYETHYL METHACRYLATE GRAFTED THERETO" filed October 18, 1996, the disclosure o f which is incorporated herein by reference in it entirety and is made a part hereof.

The modified polyolefin constituent of the compositons c an have as little as 0.1 weight percent of a compatibilizing monomer grafted thereto. Desirably, the modified polyolefin has grafted thereto from about 1 weight percent to about 20 weight percent, based on the weight of polyolefin, of a compatibilizing monomer . More desirably, the modified polyolefin has from about 1 weight percent to about 10 weight percent, based on the weight o f polyolefin, of a compatibilizing monomer is grafted to the polyolefin.

A variety of polar, vinyl monomers, oligomer, and polymers and mixtures of the above may be useful as a compatabiuzing monomer in the present invention, as long as, the monomers , oligomers and polymers are capable of covalent bonding with th e parent polymer(s), the polyolefins. Ethylenically unsaturated monomers containing a polar functional group, such as hydroxyl, carboxyl, amino, carbonyl, halo, glycidyl, cyano, thiol, sulfonic, sulfonate, etc. are appropriate for this invention and are suggested. Desired ethylenically unsaturated monomers include acrylates and methacrylates. Suggested polar vinyl monomers include, but are not limited to: 2-hydroxyethyl acrylate, 2 - hydroxyethyl methacrylate, poly(ethylene glycol) acrylates, poly(ethylene glycol) methacrylates, poly(ethylene glycol) diacrylates, acrylic acid, methacrylic acid, maleic anhydride, itaconic acid, acrylamide, glycidyl methacrylate, 2-bromoethyl acrylate, 2-bromoethyl methacrylate, carboxyethyl acrylate, sodium acrylate, 3-hydroxypropyl methacrylate, 3-hydroxypropyl acrylate, 2-chloroacrylonitrile, 4-chlorophenyl acrylate, 2 - cyanoethyl acrylate, glycidyl acrylate, 4-nitrophenyl acrylate, pentabromophenyl acrylate, poly(propylene glycol) acrylates, poly(propylene glycol) methacrylates, 2-propene- l -sulfonic acid and its sodium salt, 2-sulfoethyl acrylate, 2-sulfoethyl methacrylate, 3-sulfopropyl acrylate, 3-sulfopropyl methacrylate, and derivatives and analogs of the above. Suggested derivatives, include, but are not limited to, poly(ethylene glycol) ethyl ether acrylates, poly(ethylene glycol) alkyl ether acrylates, poly (ethylene glycol) alkyl ether methacrylates, an d poly(ethylene glycol) ethyl ether methacrylates of various molecular weights.

Any polar vinyl monomer or a mixture of monomers including a polar vinyl monomer or monomers may be added t o and reacted with the polyolefin separately from and prior to, o r during the blending process with the poly(ethylene oxide). The addition of a polar vinyl monomer and an initiator to the process is desirable. The polymers and the monomer(s) may be added simultaneously. For example, the polymer, the initiator and the monomer(s) may be added together into the hopper of a n extruder, barrel #1. It is more desirable to add the polymers t o the reactive vessel first and to melt the polymers before adding either the initiator or monomer. Examples of such methods include melting the polymers and then injecting a solution comprising initiator and monomer into the molten polymers; an d adding the initiator and then adding the monomer or mixture o f monomers to the molten polymers. It is even more desirable t o add and disperse the monomer(s) in the molten polymers before adding the initiator. Thus, it is desired to add the polymers to th e extruder first and then inject and disperse the monomer(s) in the polymers before adding initiator.

Poly(ethylene oxide) resins suitable for the present invention can have an average molecular weight ranging from about 100,000 to about 8,000,000 grams per mol. Desirable, water-soluble poly(ethylene oxide)s are available from Union Carbide Corporation under the tradename of POLYOX® . Typically, poly(ethylene oxide) is a dry, free-flowing, white powder having a crystalline melting point in the order of about 650°C, above which the poly(ethylene oxide) resin becomes thermoplastic and can b e formed by molding, extrusion and other methods known in the art. The poly(ethylene oxide) may also be grafted and can b e grafted before or during mixing with the polyolefin. Suggested monomers and amounts of monomer that can be grafted include the monomers and amounts of monomer as described above for grafting polyolefins. Grafting of poly(ethylene oxide) is described in greater detail in the commonly assigned U.S. Application No. 09/002, 197 entitled "METHOD OF MODIFYING POLY(ETHYLENE OXIDE)" filed December 31 , 1997, the disclosure of which is incorporated herein by reference in it entirety and is made a p art hereof.

The water-responsive compositions comprise a blend o f from about 1 weight percent to about 55 weight percent polyolefin and from about 45 weight percent to about 99 weight percent poly(ethylene oxide). In one embodiment, the water- responsive compositions are water-dispersible. The water- dispersible compositions comprise a blend of from about 1 weight percent to about 35 weight percent polyolefin and fro m about 65 weight percent to about 99 weight percent poly(ethylene oxide). Desirably, the water-dispersible compositions comprise from about 1 weight percent to about 2 0 weight percent of polyolefin and from about 80 weight percent t o about 99 weight percent poly(ethylene oxide) and, more desirably, from about 1 weight percent to about 15 weight percent of polyolefin and from about 85 weight percent to about 99 weight percent poly (ethylene oxide).

In another embodiment, the water-responsive compositions are water disintegratable. The water-disintegratable compositions comprise a blend of from about 35 weight to about 45 weight percent of grafted polyolefin and from about 55 weight percent to about 65 weight percent poly(ethylene oxide). In yet another embodiment, the water-responsive compositions are water weakenable. The water-weakenable compositions comprise a blend of from about 45 weight percent to about 55 weight percent of polyolefin and from about 45 weight percent to about 55 weight percent of poly(ethylene oxide).

Articles manufactured from compositions of the pre sent invention may be selectively water responsive. The water responsiveness of articles manufactured form the compositions of the present invention can be selected by blending th e component polymers of the compositions, polyolefin a n d poly(ethylene oxide), with the above ranges. Non-limiting examples of various water-responsive articles that can b e manufactured using the composition of the present invention include thermoplastic tampon tubes, garbage bags, thermoplastic films, fibers and the like. To have a water response time of less than about 2 minutes, desirably, the wall thickness or caliper o f the article, e.g., the tampon or film is 5 mils or less. One would understand that an article having a caliper greater than 5 mils would still be water-responsive but may take longer than 2 minutes after being subjected to water before becoming affected.

It is to be understood that, as for a film, "caliper" and "thickness" may be used interchangeably. However, in a shaped article, such as a tube or other configuration having a wall, the caliper of the wall would more accurately describe the thickness measurement. Processing characteristics of the compositions can b e enhanced by the incorporation of lubricants, slip agents and various known additives into the compositions. Generally, such additives are incorporated in the compositions in amounts up t o about 5 weight percent. A typical blend formulation including a lubricant would be in the order of about 75 weight percent o f poly(ethylene oxide), about 20 weight percent of a polyolefin an d about 5 weight percent of a lubricant. Lubricants are well known in the art and include TWEEN® 20, TURGITOL® NP13 available from Union Carbide, and various fatty acids such as KENAMIDE® E available from Witco Chemical.

In addition, the compositions may contain o ther components to enhance the properties of the resulting material. For example, polyethylene glycol can be added to lower the melt viscosity of the melted blend to a range suitable for other processes such as meltblown or meltsprayed nonwoven materials . The amount of polyethylene glycol can be from about 0.1 weight percent to about 10 weight percent. Suitable polyethylene glycols are available from Union Carbide under the tradename

CARBOWAX®.

Importantly, the water-responsive blends of the pre sent invention are capable of being thermoformed using conventional techniques known in the art but yet do not form a single phase blend morphology. As can be seen from Figures 1 and 2, a n article formed in accordance with the invention exhibits two- phase morphology where one polymer forms a continuous phase and the second polymer forms a dispersed or discontinuous phase. Articles made from blends of unmodified polyethylene and poly(ethylene oxide) exhibit water-responsiveness at up t o about 35 weight percent of unmodified polyethylene. Surprisingly, articles made from blends of grafted polyethylene and poly(ethylene oxide) exhibit water-responsiveness up t o about 55 weight percent of grafted polyethylene. The polyolefin and poly(ethylene oxide) blends of the invention can be prepared by mixing the desired weight ratio o f the constituents into a blend using any standard equipment commonly used for blending thermoplastic resins. For example, a batch or continuous blender may be used to blend the polyolefin and poly (ethylene oxide) using heat and high shear. Although n o t preferred, a single screw or twin screw extruder that utilizes various mixing screw sections, kneading sections and the like c an be used. After melt blending, the composition may be solidified and pelletized or extruded into a film using techniques known in the art.

The present invention is illustrated in greater detail by th e specific examples presented below. It is to be understood that these are illustrative embodiments and are not intended to b e limiting of the invention, but rather are to be construed broadly within the scope and content of the appended claims. In each o f the examples below, 5 mil films were prepared from the melt blends using a Carver hot press with two heated platens at a temperature of 190°C and a pressure of 15,000 psi for 3 minutes .

In all the examples, a relatively short but determinable disintegration time was desired.

Water Responsiveness Test: To determine the water-responsiveness of an article, a blend in accordance with this invention, was pressed into a film. A section of the film measuring about 0.25 of an inch by about 0.5 of an inch was removed. Using a pair of tweezers to hold the section of film, the film was immersed into a scintillation vial filled with 20 milliliters of water and held for 2 minutes. After 2 minutes, if the film begin to disperse or disintegrate, the contents of the scintillation vial were emptied through a "20 mesh" U.S.A. Standard Testing Sieve (ASTME-11 Specification, No. 20).

If the film did not disperse or disintegrate, the film was held immersed in the water for additional 3 minutes to observe any loss in rigidity. The vial was rinsed with 20 milliliter of water from a squeeze bottle and emptied through the sieve. In the examples, the following terms are used to describe the effect of water on the section of film:

Water dispersible: the film dissolves or breaks into pieces smaller than a 20-mesh screen after 2 minutes. Water disintegratable: the film breaks into multiple pieces after 2 minutes with some of film caught by a 20-mesh screen. Water weakenable: the film remains in one piece but weakens an d loses rigidity significantly in 5 minutes.

Water stable: the film remains in one piece and does not lose any of its rigidity after 5 minutes.

Fx ample 1

A blend containing 21 grams of low density polyethylene having a melt index of 1.9 g/10 minute (available from Dow Chemical) and 21 grams of poly(ethylene oxide), having a molecular weight of 200,000 g/mol (POLYOX WSR N-80 is available from Union Carbide) was prepared using a Haake Rheomix 600 twin-roller mixer (available from Haake, 53 West Century Rd. Paramus, NJ, 07652). Each zone of the Haake mixer was preheated to 180°C. The material was mixed for 20 minutes at a screw speed of 150 rpm. After 20 minutes, the melt was removed from the mixer and cooled in air. The film was determined to be water stable.

Example 2

The constituents of Example 1 were blended using

12.6 grams of low-density polyethylene and 29.4 grams o f poly(ethylene oxide) in the Haake Rheomix mixer for 20 minutes at a screw speed of 150 rpm. After 20 minutes, the melt was removed from the mixer and cooled in air. Figure 1 is a photomicrograph of the fracture surface of a 5-mil film of this composition using scanning electron microscopy. The film was determined to be water dispersible.

Example 3

The constituents of Example 1 were blended using 4.2 grams of low-density polyethylene and 37.8 grams of poly(ethylene oxide) in a HAAKE Rheomix mixer for 20 minutes at a screw speed of 150 rpm. After 20 minutes, the melt was removed from the mixer and cooled in air. The film was determined to be water dispersible.

Example 4

A blend containing 21 grams of a modified low-density polyethylene and 21 grams of poly(ethylene oxide) was prepared using the Haake Rheomix mixer for 20 minutes at a screw speed of 150 rpm. After 20 minutes, the melt was removed from the mixer and cooled in air. The low-density polyethylene was modified by grafting 11.1 weight percent of a compatabiuzing monomer, specifically 2-hydroxyethyl methacrylate, to the polyethylene. The film was determined to be water weakenable.

Example 5

A blend containing 18.9 grams of a modified low-density polyethylene of Example 4 and 23.1 grams of poly (ethylene oxide) was prepared using the Haake Rheomix mixer for 2 0 minutes at a screw speed of 150 rpm. After 20 minutes, the melt was removed from the mixer and cooled in air. The film was determined to be water disintegratable. The film lost rigidity a nd curled after 19 seconds and began forming fibers after 69 seconds. The film began to disintegrate after 90 seconds.

Example 6

A blend containing 16.8 grams of a modified low-density polyethylene of Example 4 and 25.2 grams of poly(ethylene oxide) was prepared using the Haake Rheomix mixer for 2 0 minutes at a screw speed of 150 rpm. After 20 minutes, the melt was removed from the mixer and cooled in air. The film was determined to be water disintegratable. The film lost rigidity and curled after 11 seconds and began forming fibers after 6 1 seconds. The film began to disintegrate after 90 seconds.

Example 7

A blend containing 14.7 grams of a modified low-density polyethylene of Example 4 and 27.3 grams of poly(ethylene oxide) was prepared using the Haake Rheomix mixer for 2 0 minutes at a screw speed of 150 rpm. After 20 minutes, the melt was removed 5 from the mixer and cooled in air. The film was determined to be water-disintegratable. The film lost rigidity and curled after 10 seconds and began forming fibers after 3 3 seconds. The film began to disintegrate after 33 seconds.

Example 8 A blend containing 12.6 grams of a modified low-density polyethylene of Example 4 and 29.4 grams of poly(ethylene oxide) was prepared using the Haake Rheomix mixer for 20 minutes at a screw speed of 150 rpm. After 20 minutes, the melt was removed from the mixer and cooled in air. Fig. 2 is a photomicrograph of the fracture surface of a 5-mil film of this composition using scanning electron microscopy. The film was determined to be water dispersible.

Example 9

A blend containing 4.2 grams of a modified low-density polyethylene of Example 4 and 37.8 grams of poly(ethylene oxide) was prepared using the Haake Rheomix mixer for 2 0 minutes at a screw speed of 150 rpm. After 20 minutes, the melt was removed from the mixer and cooled in air. The film was determined to be water dispersible.

Example 10

This example describes the preparation of poly(ethylene glycol) ethyl ether methacrylate grafted polyethylene. The grafted polyethylene was prepared by a reactive extrusion process on a ZSK-30 twin-screw extruder manufactured by Werner & Pfleiderer Corporation of Ramsey, New Jersey. The extruder has a pair of screws, which contain a number o f conveying, kneading, and left-handed screw elements to provide high intensity distributive and dispersive mixing. The two screws are co-rotating. The nominal screw diameters are 30 mm. The screw lengths are 1328 mm. The extruder has 14 processing barrels, numbered consecutively from 1 to 14 from the feed barrel to the die. The first barrel, barrel #1, received polyethylene and was not heated but cooled by water. The other barrels were heated. The monomer, poly(ethylene glycol) ethyl ether methacrylate

(abbreviated as PEGEEMA and available from Aldrich o f Milwaukee, Wisconsin had a number average molecular weight o f approximately 246 g/mol, catalog number 40,954-5). PEGEEMA is a derivative of polyethylene glycol methacrylate (PEGMA). The PEGEEMA was injected into barrel #5 and the initiator was injected to barrel #6. Both the monomer and the initiator were inj ected via a pressured nozzle injector, also manufactured by Werner & Pfleiderer. The first heating zone was heated to 170°C; all th e other heating zones were heated to 180°C. The screw speed was set at 300 rpm.

A low-density polyethylene having a melt index of 1.9 g/ 1 0 min (available from Dow) was fed to the feed throat at a rate o f 20 lb/hr through a gravimetric feeder manufactured by K-Tron o f Pitman, New Jersey. The PEGEEMA was fed to barrel #5 at a rate of 2 lb/hr, and the initiator, LUPERSOL 101 , was fed to barrel # 6 at a rate of 0.1 lb/hr. The resulting grafted polyethylene, was cooled in a 20-foot water bath and subsequently pelletized.

Example 1 1 The same polyethylene, PEGEEMA monomer, initiator, an d equipment as in Example 11 were used, except that the rate o f PEGEEMA was 1 lb/hr and the rate of LUPERSOL 101 was 0.07 lb/hr . Example 12

The same polyethylene, PEGEEMA monomer, initiator, and equipment as in Example 11 were used, except that the rate o f PEGEEMA was 0.5 lb/hr and the rate of LUPERSOL 101 was 0.05.

Example 1

This example describes the method for making 2 - hydroxyethyl methacrylate (abbreviated as HEMA) grafted poly(ethylene oxide). POLYOX WSR N-750 having an approximate molecular weight of 300,000 g/mol was fed to the feed throat of the ZSK-30, twin-screw extruder, at a feeding rate of 20 lb/hr .

HEMA was fed to the same extruder at barrel #5 at a rate of 0.3 lb/hr and peroxide initiator was fed to the barrel #6 extruder at a rate of 0.03 lb/hr. The resulting grafted polyethylene oxide was cooled on a 15-foot conveyer belt fan-cooled by air.

Subsequently, the grafted PEO was pelletized.

Example 14 A blend containing 4.2 grams of a modified low-density polyethylene of Example 4 and 37.8 grams of poly(ethylene oxide) (PEO) grafted with 1.5 percent by weight of 2-hydroxyethyl methacrylate was prepared using, the Haake Rheomix mixer a t 180°C and at a screw speed of 150 rpm for 20 minutes. After 20 minutes, the melt was removed from the mixer and cooled in air.

A film was pressed from this blend. The film was determined t o be water dispersible. Example 15

A blend containing 8.4 grams of a modified low density polyethylene of Example 4 and 33.6 grams of PEO grafted with 1.5% by weight of 2-hydroxyethyl methacrylate (HEMA) was prepared using the Haake Rheomix mixer, at 180°C and a screw speed of 150 rpm for 20 minutes. After 20 minutes, the, melt was removed from the mixer and cooled in air. A film was pressed from this blend. The film was determined to be water dispersible.

While the invention has been described with reference t o preferred embodiments of the invention, it is to be appreciated that various substitutions, changes, omissions and modifications may be made without departing from the scope of the invention as defined by the appended claims.

Claims

We claim:

1 . A composition of matter comprising a blend of from about 65 weight percent to about 99 weight percent of poly(ethylene oxide) and from about 1 weight percent to about 35 weight percent of a grafted polyolefin, wherein the of poly(ethylene oxide) may be a grafted poly(ethylene oxide) or an ungrafted poly(ethylene oxide).

2 . The composition of matter of Claim 1, wherein the blend comprises from about 80 weight percent to about 99 weight percent of poly(ethylene oxide) and from about 0.1 weight percent to about 20 weight percent of grafted polyolefin.

3 . The composition of matter of Claim 1, wherein the blend comprises from about 85 weight percent to about 99 weight percent of poly (ethylene oxide) and from about 1 weight percent to about 15 weight percent of grafted polyolefin.

4 . The composition of matter of Claim 1, wherein the grafted polyolefin is grafted with a polar vinyl monomer, oligomer, o r polymer selected from the group consisting of 2-hydroxyethyl acrylate, poly(ethylene glycol) acrylates, poly(ethylene glycol) methacrylates, poly(ethylene glycol) diacrylates, acrylic acid, methacrylic acid, maleic anhydride, itaconic acid, acrylamide, glycidyl methacrylate, 2-bromoethyl acrylate, 2-bromoethyl methacrylate, carboxyethyl acrylate, sodium acrylate, 3 - hydroxypropyl methacrylate, 3-hydroxypropyl acrylate, 2-chloroacrylonitrile, 4-chlorophenyl acrylate, 2-cyanoethyl acrylate, glycidyl acrylate, 4-nitrophenyl acrylate, pentabromophenyl acrylate, poly (propylene glycol) acrylates , poly(propylene glycol) methacrylates, 2-propene- l -sulfonic acid and its sodium salt, 2-sulfoethyl acrylate, 2-sulfoethyl methacrylate, 3-sulfopropyl acrylate, 3-sulfopropyl methacrylate, and derivatives and analogs of the above.

5 . The composition of matter of Claim 1 wherein the grafted polyolefin is grafted with from about 0.1 to about 20 weight percent of an acrylate, a methacrylate or a combination thereof relative to the weight of the polyolefin.

6 . A water-dispersible article comprising from about 65 weight percent to about 99 weight percent of poly (ethylene oxide) an d from about 1 weight percent to about 35 weight percent of a grafted polyolefin.

7 . The water-dispersible article of Claim 6, wherein th e polyolefin has grafted thereto from about 1 weight percent t o about 20 weight percent of a compatibilizing monomer.

8 . The water-dispersible article of Claim 7, wherein the compatabiuzing monomer is an acrylate or a methacrylate.

9 . The water-dispersible article of Claim 7, wherein the compatibalizing monomer is selected from the group consisting of 2-hydroxyethyl acrylate, poly(ethylene glycol) acrylates, poly(ethylene glycol) methacrylates, poly(ethylene glycol) diacrylates, acrylic acid, methacrylic acid, maleic anhydride, itaconic acid, acrylamide, glycidyl methacrylate, 2-bromoethyl acrylate, 2-bromoethyl methacrylate, carboxyethyl acrylate, sodium acrylate, 3-hydroxypropyl methacrylate, 3-hydroxypropyl acrylate, 2-chloroacrylonitrile, 4-chlorophenyl acrylate, 2 - cyanoethyl acrylate, glycidyl acrylate, 4-nitrophenyl acrylate, pentabromophenyl acrylate, poly(propylene glycol) acrylates, poly(propylene glycol) methacrylates, 2-propene- l -sulfonic acid and its sodium salt, 2-sulfoethyl acrylate, 2-sulfoethyl methacrylate, 3-sulfopropyl acrylate, 3-sulfopropyl methacrylate, and derivatives and analogs of the above.

1 0. A composition of matter comprising a blend of from about 1 weight percent to about 55 weight percent of a polyolefin grafted with a polar, vinyl monomer grafted and from about 4 5 weight percent to about 99 weight percent of poly(ethylene oxide) .

1 1 . The composition of matter of Claim 10, wherein the polyolefin has grafted thereto from about 0.1 weight percent t o about 20 weight percent of polar vinyl monomer, based on th e weight of the polyolefin prior to grafting.

1 2. The composition of matter of Claim 11 , wherein the polar vinyl monomer is selected from the group consisting of 2 - hydroxyethyl acrylate, poly(ethylene glycol) acrylates, poly(ethylene glycol) methacrylates, poly(ethylene glycol) diacrylates, acrylic acid, methacrylic acid, maleic anhydride, itaconic acid, acrylamide, glycidyl methacrylate, 2-bromoethyl acrylate, 2-bromoethyl methacrylate, carboxyethyl acrylate, sodium acrylate, 3-hydroxypropyl methacrylate, 3-hydroxypropyl acrylate, 2-chloroacrylonitrile, 4-chlorophenyl acrylate, 2 - cyanoethyl acrylate, glycidyl acrylate, 4-nitrophenyl acrylate, pentabromophenyl acrylate, poly(propylene glycol) acrylates, poly(propylene glycol) methacrylates, 2-propene- l -sulfonic acid and its sodium salt, 2-sulfoethyl acrylate, 2-sulfoethyl methacrylate, 3-sulfopropyl acrylate, 3-sulfopropyl methacrylate, and derivatives and analogs of the above.

1 3 . The composition of matter of Claim 10, wherein the polar vinyl monomer is an acrylate or methacrylate.

14. The composition of matter of Claim 13, wherein the polar vinyl monomer is a poly(ethylene glycol) methacrylate or a derivative or an analog thereof.

15 . The composition of matter of Claim 10, wherein the blend comprises : from about 1 weight percent to about 35 weight percent o f polyolefin grafted with a polar vinyl monomer and is selected from the group consisting of grafted polyethylenes and grafted polypropylenes, and from about 65 weight percent to about 99 weight percent o f poly(ethylene oxide), wherein the blend is water dispersible.

1 6. The composition of matter of Claim 10, wherein the blend comprises : from about 35 weight percent to about 45 weight percent o f polyolefin grafted with a polar vinyl monomer selected from th e group consisting of grafted polyethylenes and grafted polypropylenes, and from about 55 weight percent to about 65 weight percent o f poly(ethylene oxide), wherein the blend is water-disintegratable.

17 . The composition of matter of Claim 10, wherein the blend comprises : from about 45 weight percent to about 55 weight percent o f polyolefin grafted with a polar vinyl monomer selected from th e group consisting of grafted polyethylenes and grafted polypropylenes, and from about 45 weight percent to about 55 weight percent o f poly(ethylene oxide), wherein the blend is water weakenable.

1 8 . The blend of Claim 10, wherein the polyolefin grafted with a polar vinyl monomer has a melt index of from about 0.01 decigrams per minute to about 100 decigrams per minute at 2. 1 6 kg and 190°C .

1 9. A water-responsive article comprising from about 1 weight percent to about 55 weight percent of a grafted polyolefin having grafted thereto from about 0.1 weight percent to about 20 weight percent of a polar vinyl monomer, oligomer or macromonomer based on the weight of polyolefin, and from about 45 weight percent to about 99 weight percent of poly (ethylene oxide).

20. The water-responsive article of Claim 19, wherein the grafted polyolefin is poly(ethylene glycol) methacrylate grafted polyolefin

2 1 . The water-responsive article of Claim 19 wherein the polyolefin has grafted thereto from about 0.1 weight percent t o about 20 weight percent, based on the weight of polyolefin, polar vinyl monomer, polar vinyl oligomer, polar vinyl macromonomer or a combination thereof.

22. The water-responsive article of Claim 19, wherein the polar vinyl monomer, oligomer or polymer is an acrylate o r methacrylate.

23 . The water-responsive article of Claim 19, comprising from about 1 weight percent to about 35 weight percent of grafted polyolefin and from about 65 weight percent to about 99 weight percent of poly(ethylene oxide), wherein the water-responsive article is water dispersible.

24. The water-responsive article of Claim 19, comprising from about 35 weight percent to about 45 weight percent of grafted polyolefin and from about 55 weight percent to about 65 weight percent of poly(ethylene oxide), wherein the water-responsive article is water disintegratable.

25. The water-responsive article of Claim 19, comprising from about 45 weight percent to about 55 weight percent of the modified polyolefin and from about 45 weight percent to about 55 weight percent of poly (ethylene oxide) wherein the article is water weakenable.

26. A method of making a water-dispersible article comprising the steps of blending under melt conditions from about 1 weight percent to about 35 weight percent of a grafted polyolefin an d from about 65 weight percent to about 99 weight percent of poly(ethylene oxide) and forming the article from the blend.

27. The method of Claim 26, wherein the grafted polyolefin has grafted thereto from about 0.1 weight percent to about 20 weight percent, based on the weight of polyolefin prior to grafting.

28 . A method of making a water-responsive article comprising the steps of blending under melt conditions from about 1 weight percent to about 55 weight percent of a polyolefin grafted with a polar vinyl monomer, oligomer, macromonomer or combination thereof and from about 45 weight percent to about 99 weight percent of poly(ethylene oxide) wherein the polar vinyl monomer, oligomer o r macromonomer is selected from the group consisting of 2 - hydroxyethyl acrylate, poly(ethylene glycol) acrylates, poly(ethylene glycol) methacrylates, poly(ethylene glycol) diacrylates, acrylic acid, methacrylic acid, maleic anhydride, itaconic acid, acrylamide, glycidyl methacrylate, 2-bromoethyl acrylate, 2-bromoethyl methacrylate, carboxyethyl acrylate, sodium acrylate, 3-hydroxypropyl methacrylate, 3-hydroxypropyl acrylate, 2-chloroacrylonitrile, 4-chlorophenyl acrylate, 2 - cyanoethyl acrylate, glycidyl acrylate, 4-nitrophenyl acrylate, pentabromophenyl acrylate, poly(propylene glycol) acrylates, poly(propylene glycol) methacrylates, 2-propene- l -sulfonic acid and its sodium salt, 2-sulfoethyl acrylate, 2-sulfoethyl methacrylate, 3-sulfopropyl acrylate, 3-sulfopropyl methacrylate, and derivatives and analogs of the above.