MXPA00012546A - Water-modifiable flushable polyolefin-containing film and article made therefrom - Google Patents

Abstract

The invention provides a water degradable polyolefin-containing film having greater than about 55 weight percent of a polyolefin and less than about 45 weight percent of poly(ethylene oxide) of weight average molecular weight of less than about 100,000. Preferably, the polyolefin is low density polyethylene. The polyolefin-containing film, when immersed in water for about 30 seconds, loses at least 10%in two or more of the tensile properties:percent strain-to-break, peak stress, energy-to-break and modulus when compared to the dry or pre-immersion values. Also provided are flushable personal care articles such as infant diapers, feminine hygiene napkins, and adult incontinence garments having a backing or barrier layer comprising a water degradable polyolefin-containing film of the invention.

Description

OUE FILM CONTAINS DISPOSABLE POLYOLEFIN WITH WATER DISCHARGE AND AMENDED WITH WATER AND ARTICLE MADE OF THE SAME Technical Field of the Invention The present invention relates to a film containing disposable polyolefin with discharge of degradable water with water. More particularly, the present invention relates to a film containing disposable water-degradable or water-degradable polyolefin having more than about 55 percent by weight of a polyolefin and less than about 45 percent by weight of poly ( ethylene oxide).

BACKGROUND OF THE INVENTION Personal care products, such as infant diapers, sanitary napkins, adult incontinence garments, and the like are generally constructed of a number of different components and materials. Such articles typically have some part as usually the backing layer, the liner, the separating barrier constructed from a liquid repellent film material. This repellent material is suitably constructed to minimize or prevent the exudation of the liquid absorbed from the article and to obtain a greater utilization of the absorbent capacity of the product. Commonly used liquid repellent films include plastic materials such as polyethylene films and the like.

Even when such products are relatively cheap, sanitary and easy to use, the disposal of soiled products is not without its problems. With major interest being placed on protecting the environment, and the need to develop materials that are more compatible with existing waste disposal technologies while still delivering to the consumers the performance they expect. An alternative of disposition idea would be the use of private residential septic systems and d treatment of municipal drainages. The products suitable for disposal in drainage systems can be disposed of by discharging water in a convenient toilet and called "disposable with water discharge".

Even though the discharge with water discharge of such items will be convenient, the liquid repellent material which normally does not disintegrate in the water tends to plug the toilets and drainage pipes. It is therefore necessary, even if undesirable, to separate the barrier film material from the absorbent article before discharging with water discharge.

In addition to the article itself, typically the packaging in which the disposable article is distributed is also made of a water resistant material. The resistance to water and necessary to avoid the degradation of the package by the environmental conditions and to protect the disposable articles contained there. Although this package can be safely stored with another waste for commercial disposal, and especially in the case of the individual package of the products, it is often more convenient to dispose of the container in the toilet with the discarded article discarded. However, in cases where such a package is composed of a water resistant material, clogging of the toilet drains typically occurs.

Desirably, a disposable product with water drainage or commercial drainage must respond relatively to the water and be transportable in the drainage system. Commercially available water-soluble polymers, such as poly (ethylene oxide) (PEO), poly (vinyl alcohol) (PVOH) acrylamide polymers, acrylic acid-based polymers, cellulose derivatives possess the characteristic desired for waste with water discharge such water solubility and / or dispersibility in water. However, due to degradability in use and degradation in storage these materials function poorly as components in personal care products. Other disadvantages are that these polymers are difficult to process and are essentially more expensive than polyolefins.

The requirements for a disposable product with water discharge and functional provide a dessicant substance to find suitable materials with the desired properties In the attempt to overcome the problem of waste with water discharge of a waterproof film the prior art modified h the water resistant polymer. One of the most useful ways to modify polymers involves mixing them with other polymers of different structures and properties.

Samples of polyolefin polymers and poly (ethylene oxide) have been shown to be water modifiable. Expected levels of percent by low weight of polyolefins Such mixtures will be anticipated as being disposable as water discharge when exposed to water in a toilet but n possess the dry mechanical properties required for functionality in use. However, the high content of poly (ethylene oxide) makes such materials prohibitively expensive for use in disposable personal hygiene articles such as sanitary napkins, similar diapers. Polymer blends of polyolefins and poly (ethylene oxide) containing more than about 45 percent by weight of the polyolefin are generally water resistant and are not modifiable with water. In view of the prior art problem, it remains highly desirable to provide a modifiable film with water having a substance part thereof composed of a polyolefin. More desirably, the modifiable film with water should be more than about 5 by weight of a polyolefin. When dry, the film must have the mechanical properties necessary for operation. When wet, the film must lose at least a part of its mechanical properties which makes the film disposable with water discharge and transportable in a drainage system. Such films can be used to make disposable barrier films with water discharge for personal care products.

It is therefore an object of the invention to provide a film containing polyolefin that is water-modifiable or water-degradable which contains higher levels of polyolefin content. More specifically, it is an object of the invention to provide a film containing polyolefin having more than about 55 percent by weight of a polyolefin and less than about 45 percent by weight of poly (ethylene oxide) which is modifiable with water or degradable with water.

Synthesis of the Invention In a main embodiment, the present invention provides a film containing polyolefin degradable in water comprising more than about 55 percent by weight of a polyolefin and less than about 45 percent by weight of polyethylene oxide where the poly (ethylene oxide) has a weight average molecular weight of less than about 100 thousand. The film of the invention has a loss of at least 10 percent in two or more tensile properties selected from the percent of tension at break, peak voltage, energy at break and modulus after being immersed in water for 30 seconds.

In an alternate embodiment, the present invention provides a disposable person care article with water discharger having a barrier or backing film comprising more than about 55 po weight of a polyolefin and less than about 45 percent po weight of poly (ethylene oxide) wherein the poly (ethylene oxide) has a molecular weight of less than about 100 mil.L film of the invention has a loss of at least 1 percent in two or more tensile properties selected d tension to break, peak voltage, energy to break module after becoming submerged in water for 30 seconds.

Detailed description of the invention As used here "modifiable with water" "degradable with water" means that a film of 4 thousandth of thickness (1 thousandth is equal to 0.001 of an inch or 0.02 millimeters), when submerged in water for 30 seconds of having modified by more than 10 percent of 2 or more of the following voltage properties: percent of voltage at peak voltage breaking, breaking energy and modulus. To determine the degree of modification, the "wet" values are compared to the presumed or dried film values.

The term "personal care product" "personal care item" means articles such as infant diapers, sanitary napkins, adult incontinence garments and the like.

By the term "backing layer" or "barrier layer" it means that the component of an infant diaper, of a sanitary napkin, of an adult incontinence garment or the like which is worn during normal use further away of the user's body and which serves to minimize or prevent the exudation of the absorbed liquid.

Although the present invention is described with reference to a film modifiable with water and, in particular with personal care articles having a backing layer, liner or barrier layer comprising such films, one skilled in the art will understand that the composition of the invention can be used to make other thermoplastic articles that can be extruded or molded in which the desired property of water degradability is needed, such as in packaging articles and the like.

In one embodiment of the invention, the film degradable in water or modifiable in water comprises more than about 55 percent by weight of a polyolefin and less than about 45 percent by weight of poly (ethylene oxide). Desirably, the film Water-modifiable comprises from about 55 percent by weight about 85 percent by weight of a polyolefin and from about 45 percent by weight about 15 percent by weight of poly (ethylene oxide). More desirably, the water-modifiable film comprises from about 65 percent by weight about 85 percent by weight of a polyolefin and from about 3 percent by weight about 15 percent by weight of poly (ethylene oxide). . The poly (ethylene oxide) useful for making the film has a weight average molecular weight of less than about 100 thousand. The preferred polyolefin of polyethylene with a low density polyethylene ("LDPE") is particularly preferred.

The saturated ethylene polymers useful in the practice of this invention with the homopolymers of ethylene preferably the low density polyethylene, and are essentially linear in structure. As used herein the term "saturated" refers to polymers which are completely saturated but also include polymers containing up to about 5 percent unsaturation.

The low density polyethylene suitable for use in the films of this invention has a density d less than about 0.94 grams per cubic centimeter and is usually in the range of 0.91 grams per cubic centimeter around 0.93 grams per cubic centimeter. The low density polyethylene has a melt index ranging from about 0.05 dg / minute to about 100 dg / minute and desirably from 0.05 dg / minute to about 20 dg / minute. Ultra low density polyethylene can also be used according to the present invention. Generally, ultra low density polyethylene has a density of less than 0.90 g per cubic centimeter.

A low density polyethylene material commercially available and suitable for use in the polymer blend of the present invention is the linear low density polyethylene 5011 available from Dow Plastics Division of Do Chemical Company, of Midland, Michigan. The resin has a density of 0.922 grams per cubic centimeter and a melted d-index of 1.19 dg / minute.

A low molecular weight polyethylene oxide suitable for use in the polymer blends of the present invention is available from Union Carbide Corporation, d. Danbury, Connecticut under the trade name Polyox marc registered class SN-10 which has a weight average molecular weight of 100 thousand. Typically, the poly (ethylene oxide) is a white powder flowing in free and dry form having a crystalline melt point in the order of 650 ° C, above which the poly (ethylene oxide) resin becomes thermoplastic and can be formed by molding, extrusion and other methods known in the art.

The water-degradable or water-modifiable polyolefin-containing films of the present invention, when immersed in water for about 3 seconds, lose more than 10 percent in at least 2 of the tensile properties: breaking stress peak, breaking energy and modulus. Typically at least 2 of the tensile properties will be reduced by more than about 25 percent, more typically, by about 2 percent around 98 percent and even more typically by at least about 30 percent around 80. percent The values in determining the extent of the loss of the tension property or the modification properties are relative to the dry condition, for example the pre-dive value for that measured property.

The present invention is illustrated in detail by the specific examples presented below. It will be understood that these examples are illustrative embodiments that are not intended to be limiting of the invention, but rather are broadly considered within the scope and content of the appended claims.

Comparative Example A A mixture of 60/40 percent by weight of low density polyethylene (PE) that has a melt index of 1.9 decigrams per minute (dg / min) and a density of 0.92 grams per cubic centimeter (g / cc) ( Dow 5031, available from Do Chemical Company, of Midland Michigan) and poly (ethylene oxide) (PEO) which has a molecular weight of 200 thousand grams per mo (POLIOX trademark WS N-80 available from Union Carbid Corporation, of Danbury Connecticut) was fed to a twin screw extruder against rotating check at a rate of pounds / hour (2.27 kilograms / hour). The extruder had a length of 300 millimeters. Each conical screw had a diameter of 30 millimeters to a supply port and a diameter of 2 millimeters in the matrix. The extruder had 4 heating zones set at l70 ° C, 180 ° C, 180 ° C and 90 ° C. The screw speed of the extruder was 150 revolutions per minute.

The film processing of all the blends was carried out using a twin screw extruder with rotary control as described above with the following modifications. The extruder included a slit matrix of inches (101.6 millimeters) at a temperature of 195 ° C. The screw speed was at 30 revolutions per minute. A cooled coiling roll was used to collect the film. The cooled roller was operated at a sufficient speed to form a film having a thickness d about 4 mils (about 0.10 millimeters and a temperature of 15-20 ° C was maintained.) Dry strain testers were carried out on a Sintech 1 / D voltage tester available from MTS System Corporation, Machesny Park, Ill. The film was cut into a type V dog bone shape according to norm ASTM D638. a separation of agarr of 30 millimeters and a crosshead speed of 4 millimeters per second.

The voltage tests in number were carried out on a Vitrodine V100 minitimensioning tester available from Chatillon, Greensboro, North Carolina. The film samples were placed in the grips and the test apparatus was submerged at room temperature, water agitated for 30 seconds. The test was then run under the same conditions as the dry stress test. The maximum tension, the percentage of tension to the break, the energy to break (as area under tension against voltage curve d) and the module were calculated using the current voltage against the voltage values recorded from the voltage tester d each tension test in dry or wet. L peak voltage was recorded as the highest voltage value. E percent of stress at break was recorded as the percentage of tension at break. The breaking energy (áre under tension against the spotting curve) was calculated by the sum of the rectangular "slices" under the curve determined for each voltage value recorded from the stress test, using the following formula: ((Value of tensionx-Value of tension ^) X (Value of tensionx + Value of tension ^,)) / 2 where "X" is the essential number of the slice. The module was calculated by the linear regression of the initial region of the stress curve versus stress. The dry and wet properties of the film produced from the mixture in Comparative Example A are indicated in Table 1 given below.

TABLE 1 Percent Loss in Stress Properties. Comparative Example A This example shows that a mixture of low density polyethylene polymer with polyethylene oxide has a weight average molecular weight of 200 mil and is water resistant. The polymer mixture was not modifiable with water after 30 seconds of immersion in the water.

Example 1 In Example 1, an extruder Werner & Pfleidere ZS -30 (available from Werner &Pfleiderer of Ramser, New Jersey) was used. The extruder had a pair of co-rotating screws arranged in parallel. The distance to the center between the two axes was 26.2 millimeters. The nominal screw diameter was 3 millimeters. The actual external screw diameter was 3 millimeters. The inner screw diameter was 21. millimeters. The thread depth was 4.7 millimeters. The extruder had 14 barrels of processing, with thirteen heated barrels divided into 7 heating zones. The overall processing length was 1340 millimeters.

A mixture of 60/40 weight percent resin by weight of low density polyethylene (Dow 5031) and poly (ethylene oxide having a weight average molecular weight of about 10,000 grams per mole (Union Carbide, POLYOX trademark WSRN 10 ) was fed to the ZSK-30 extruder at a rate of 35 pounds per hour (15.91 kilograms / hour) The seven heating zones were all set at 180 ° C. The screw speed was 30 revolutions per minute.

The wet and dry properties of the film produced from the mixture in Example 1 are indicated in the table given below.

Table 2 Percent Loss in Stress Properties Example 1 According to the invention, Example 1 was a film of a 60 percent by weight polymer blend of unmodified polyethylene and 40 percent by weight of unmodified poly (ethylene oxide) having an average molecular weight. of weight of around 100 thousand. The film of this polymer mixture was degraded with water after 30 seconds of immersion in water as shown by the data which in turn show the percent loss of tensile properties d more than 68 percent from dry to wet in all properties tested and more than 86 percent loss in percent d tension and energy at break.

Although the invention has been illustrated with reference to the preferred embodiments and illustrated in relation to a range of optional features, those skilled in the art will appreciate that various modifications or substitutions may be made as omissions and changes if departing from the spirit of the invention. and cone is defined by the appended claims. Therefore, it is intended that the above description be considered merely as an example of the preferred scope of the present invention and not be considered a limitation thereof.

Claims (19)

R E I V I N D I C A C I O N S

1. A film containing water degradable polyolefin comprising more than about 55 percent by weight of a polyolefin and less than about 45 percent by weight of poly (ethylene oxide) wherein said poly (ethylene oxide) has a weight molecular weight of less than about 10 thousand, said film has a loss of at least 10 percent in two or more tension properties selected from the percentage of stress at break, peak stress, energy to break and modulus after having Submerged in water for 3 seconds.

2. A film, as claimed in clause 1, characterized in that said film comprises d from about 55 weight percent to about 85 weight percent of a polyolefin and from about 45 weight percent to about 15 weight percent. percent by weight of poly (ethylene oxide).

3. A film, as claimed in clause 1, characterized in that said film comprises d from about 65 weight percent to about 85 weight percent of a polyolefin and from about 35 weight percent to about 15 weight percent. percent by weight of poly (ethylene oxide).

4. A film, as claimed in clause 1, characterized in that said polyolefin is low density polyethylene.

5. A film, as claimed in clause 2, characterized in that said polyolefin is low density polyethylene.

6. A film, as claimed in clause 3, characterized in that said polyolefin is low density polyethylene.

7. A film, as claimed in clause 1, characterized in that said loss in 2 or more of the stress properties greater than 25 percent after d submerged in water for 30 seconds.

8. A film, as claimed in clause 7, characterized in that said loss in 2 or more of the tensile properties is from about 25 per cent about 98 percent after being immersed in agu for 30 seconds.

9. A film, as claimed in clause 8, characterized in that said loss in 2 or more of the tensile properties is from about 25 per cent about 98 percent after being immersed in agu for 30 seconds.

10. A film, as claimed in clause 9, characterized in that said loss in 2 or more of the tensile properties is from about 25 per cent about 98 percent after being immersed in agu for 30 seconds.

11. A film, as claimed in clause 7, characterized in that said loss in 2 or more of the tensile properties is from about 30 per cent about 80 percent after being immersed in agu for 30 seconds.

12. A film, as claimed in clause 8, characterized in that said loss in 2 or more of the tensile properties is from about 30 per cent about 80 percent after being immersed in agu for 30 seconds.

13. A film, as claimed in clause 9, characterized in that said loss in 2 or more of the tensile properties is from about 30 per cent about 80 percent after being submerged in agu for 30 seconds.

14. A polyolefin-containing film comprising more than about 60 weight percent low density polyethylene and about 40 weight weight poly (ethylene oxide), wherein said polyethylene oxide has an average molecular weight of weight of less than about 100 thousand, said film has a loss of at least 1 percent in at least two tensile properties selected from the percent of tension at break, peak stress, energy at break and modulus after being submerged in water for 30 seconds.

15. An article for degradable person care in water having a backing or barrier layer comprising a film containing polyolefin comprising more than about 55 weight percent of a low density polyethylene and less than about 45 weight percent. Weight poly (ethylene oxide), wherein said poly (ethylene oxide) has a weight average molecular weight of less than about d 100 mil, said film has a loss of at least 6 percent in at least two tensile properties selected from the percent of tension to breaking peak effort, breaking energy and modulus after having submerged in water for 30 seconds.

16. An article for personal care, as claimed in clause 18, characterized in that the backing or barrier layer comprises about 60 per cent by weight of low density polyethylene and about 40 per cent by weight of poly (ethylene oxide). ethylene) wherein polyethylene oxide has a weight average molecular weight of less than about 100 thousand.

17. An article for personal care, as claimed in clause 18, characterized in that said article is a sanitary towel for women.

18. An article for personal care, as claimed in clause 18, characterized in that said article is a diaper for infant.

19. An article for personal care, as claimed in clause 18, because said article is a garment for adult incontinence. SUMMARY The invention provides a film containing degradable polyolefin in water having more than about 5 percent by weight of a polyolene and less than about 4 percent by weight of poly (ethylene oxide) of a weight average molecular weight. less than about 100 thousand Preferably, the polyolefin is low density polyethylene. The polyolefin-containing film, when immersed in water for about 30 seconds, loses at least 10 percent in two or more of the tensile properties: percent tension at break, peak effort, energy at breaking and modul when compared to the values of dry or pre-immersion. Disposable personal care items are also provided with water discharge such as infant diapers, sanitary napkins for women's hygiene and adult incontinence garments having a back-up barrier layer comprising a film that contains polyolefin degradable in water of the invention.