MXPA00001842A - Hybrid interpolymer film pouch - Google Patents

Abstract

A pouch for containing a flowable material, said pouch being made from a film in tubular form and having transversely heat-sealed ends, said film being made from at least one layer of a material comprising about 50 to about 100 parts by weight of a hybrid interpolymer of ethylene and a C3-C20 alpha-olefin made by a polymerization process using both a metallocene catalyst and a Zeigler-Natta catalyst, the hybrid interpolymer having a density of from about 0.910 to about 0.940 g/cm3, a melt index of from about 0.1 to 2.0 dg/min, and a melt strength of greater than about 3.5 Centi Newtons as determined using a Goettfert Rheotens unit at 190°C and from 0 to about 50 parts by weight of a high-pressure polyethylene having a density of from about 0.916 to about 0.924 g/cm3 and a melt index of from about 0.01 to about 10 dg/min. Also described is a process for making such pouches.

Description

FILM BAGS OF HYBRID INTERPOLIMEROS FIELD OF THE INVENTION The sealing properties of the films are key to their effective use in many packaging applications, such as, for example, disposable bags containing fluids that can be manufactured into form, fill and seal equipment employing impulse or heat sealing techniques; vacuum packaging for products of irregular shape and for food, preparations, cheeses and the like; wrapped shrunken birds; and packed skin. While this invention addresses all forms of packaging, it is of particular value in the area of liquid packaging, primarily for the manufacture of bags containing liquids. This invention relates to bags for fluid materials made from films formed from a new class of ethylene-alpha-olefin interpolymers that demonstrate superior performance in food bags, such as milk.

BACKGROUND OF THE INVENTION The packaging machinery is designed for REF: 32885 to operate at very fast speeds all the time. Such machinery requires low sealing temperatures and therefore improved hot tack resistance in films that are used to make the packing with such machines. While resistance to stickiness or hot adhesion is often a good indicator of whether a film will produce an excellent bag, other properties are provided to be of equal or greater significance, for example, resistance to melting. The metallocene ethylene-octene or ethylene-hexene interpolymers are commercially available in the density range from 0.80 to .915 gm / cc. These densities are too low in modules to be used alone to make bags for fluid materials. They must be mixed with Zeigler-Natta interpolymers or used in coextrusions to form bags for liquids. When a class of polymer is much more expensive than the conventional low-density polyethylene of Zeigler-Natta (LLDPE) and not, in its presence, it has the optimum balance of properties for applications in bags for liquids. The standard polymer of the liquid bag industry is the ethylene-octene copolymer polymerized with Zeigler-Natta catalyst. While these polymers offer acceptable performance, there is a fourth to reduce the incidence of pocket field failure caused by perforation, or seal failure through the improvement of property. 5 Now a new class of polymers is not available, which refer to Zeigler-Natta / Hybrid Metallocene catalyst interpolymers. These are formed from ethylene and alpha-olefins of 1 to 4 carbon atoms produced by a polymerization process using multiple reactors (minimum of 2) in series or in parallel or both. The process uses Zeigler-Natta and Metallocene catalysts, preferably in separate reactors to produce hybrid interpolymers with advantageous liquid packing properties. The catalysts are the single-site or metallocene catalysts and the Zeigler-Natta catalysts, both of which are well documented in the catalyst art. The resistance to hot tack is the ability of a film to seal under resistance while it is inactive in a merged state. This property is one of the most critical in packaging applications while the machines operate at high speeds and sealing performed between the sealing components by fusion of a package, so placing the There are also sealing components, and therefore the sealing under tension when the packing is formed, filled and sealed. It should be noted that in the case of fluid containing bags made in forming, filling and sealing equipment, there appears to be a correlation between the leakage frequency by the seal and resistance to hot tack. This is supported by data collected in the industry daily. As noted, the development of the catalyst single site (SSC) or metallocene technology has led approximately an improved class of polymers ranging from crystalline to elastomeric materials. These polymers have characteristics such as improved impact strength and firmness, better fusion characteristics, because of the control over the molecular structure, and improves clarity. Exxon and Dow have developed SSC or metallocene polymers and each has the benefit of a number of patents related to these polymers. Exxon is the mono- and bi-cyclopentadienil metallocenes, while Dow's focus is on cyclopentadienyl titanium metallocenes, which is called "artificial geometric catalysts". In practice, Exxon produces ethylene-butene and ethylene-hexene polymers, while Dow produces ethylene-octene polymers of the metallocene type or SSC. Dow ^^^^^^^ - • - "-? -M.'TE & fer claims that its metallocene polymers or SSC are different from those that have uniformly introduced comonomers and long chain branching that improves processability in another way in linear polymers.

ANTECEDENTS OF THE TECHNIQUE Examples of the non-hybrid Exxon polymers are found in the following patents and applications, the descriptions of which are incorporated herein by reference: US Patent No. 5,382,630 filed January 17, 1995 by Stehling et al and O93 / 03093 published on February 18, 1993 by Meka et al. These resins are commercially available from Exxon under the trademark EXACT TM. Examples of the non-hybrid polymers of Dow are found in the following North American Patents, the description of which is incorporated herein by reference: US Patent Nos. 5,508,051 issued April 16, 1996 to Falla et al; 5,360,648 issued November 1, 1994 by Falla et al; 5,278,272 issued January 11, 1994 to Lai et al; and 5,272,236 issued December 21, 1993 to Lai et al. These resins are commercially available under the trademark AFFINITY ™ In PCT International Publication WO 95/10566 of DUPONT CA ADA INC. published on April 20, 1995, the description of which is incorporated herein by reference, describes bags for fluid materials wherein the sealing film is made of a linear copolymer of ethylene SSC and at least one alpha-olefin of 1 to 4 carbon atoms. Mixtures of these SSC interpolymers with at least one polymer selected from linear interpolymers of multi-site catalyst of ethylene and at least one alpha-olefin of 4 to 10 carbon atoms, a high pressure polyethylene and mixtures thereof. In the PCT International Publication WO 95/21743 of DUPONT CANADA INC. published on August 17, 1995, the description of which is incorporated herein by reference, describes an ethylene copolymer film of improved stiffness for use in the manufacture of bags containing fluids. Typically, the structure comprises an interposed layer of polyethylene having a thickness in the range of 5 to 20 microns and a density of at least 0.93 gm / cc and a melt index of about 1 to 10 dg / minute, at least one layer external that is a film of SSC or metallocene polyethylene / alpha-olefin which has a density in the range of 0.88 to 0.93 gm / cc. The unique requirements ia ^ ^ ut ^^^^ i ^ ^ placed in the interposed layer of stiffness are those that are of a particular thickness and density. These properties are larger in the reinforcing layer than in the metallocene layer (s) or SSC. This application indicates that the reinforcing or tightening layer is included in order for the bag containing fluid to stay up properly so that the fluid can be poured from when the bag is placed in a support container. U.S. Patents Nos. 4,503,102 (Mollison) and 4,521,437 (Storms) of DUPONT CANADA INC., The description of which is incorporated as a reference, discloses a polyethylene film for use in a formed, filled and sealed process for the manufacture of a disposable bag for liquids such as milk. US Patent No. 4,503,102 discloses bags made from a blend of a linear ethylene ethylene copolymer and an α-olefin of 4 to 10 carbon atoms and a copolymerized ethylene-vinyl acetate copolymer of ethylene and vinyl acetate. The linear polyethylene copolymer has a density of 0.916 to 0.930 g / cm3 and a melt index of 0.3 to 2.0 g / 10 minutes. The ethylene-vinyl acetate polymer has a weight ratio of ethylene to vinyl acetate of 2.2: 1 to 24: 1 and a melt index of 0.2 to 10 g / 10 minutes. The mixture described in US Pat. No. 4,503,102 has a weight ratio of linear, low density polyethylene to vinyl acetate-ethylene polymer from 1.2: 1 to 24: 1. US Patent No. 4,503,102 also discloses multilayer films having the aforementioned mixture as the sealing film. US Patent No. 4,521,437 (Storms) discloses bags made of a sealant film which is from 50 to 100 parts of a linear copolymer of ethylene and 1-octene having a density of 0.916 to 0.930 g / cm and a melt index from 0.3 to 2.0 g / 10 minutes and from 0 to 50 parts by weight of at least one polymer selected from the group consisting of a linear copolymer of ethylene and a C-Cio alpha-olefin having a density from 0.916 to 0.930 g / cm3 and a melt index of 0.3 to 2.0 g / 10 minutes, a high pressure polyethylene having a density of 0.916 to 0.924 g / cm3 and a melt index of 1 to 10 g / 10 minutes and mixtures thereof . The sealant film described in US Pat. No. 4,521,437 is selected on the basis of providing (a) bags with a substantially lower M-test value, at the same film thickness, as that obtained for bags made from film of a mixture of 85 parts of a linear ethylene / 1-butene copolymer having a density of about 0.919 mg ^ g / cm3 and a melt index of about 0.75 g / 10 minutes and 15 parts of a high pressure polyethylene having a density of about 0.918 g / cm and a melt index of 8.5 g / 10 minutes, or ( b) a test value M (2) of less than about 12%, for bags having a volume greater than 1.3 to 5 liters, or (c) a test value M (1.3) of less than about 5% for bags which have a volume of 0.1 to 1.3 liters. The M, M (2) and M (1.3) tests are defined by bag drop tests by U.S. Patent No. 4,521,437. The bags can also be made from composite films in which the sealing film forms at least the inner layer. In US Patent No. 5,288,531 to Falla et al, the disclosure of which is incorporated herein by reference, the use of polymers in the manufacture of films used to make bags containing fluids is described. These films are characterized as linear ultra-low density polyethylene ("ULDPE") and are sold commercially as ATTANE ™ by Dow. They are described as a linear copolymer of ethylene with at least one α-olefin having from 3 to 10 carbon atoms, for example, the ULDPE can be selected from interpolymers of ethylene-1-propylene, ethylene-1-butene, ethylene-1-pentene, ethylene-4-methyl-l-pentene, ethylene-1- ¿^ Lífe ^ M & Emi &hexene, ethylene-1-heptene, ethylene-1-octene and ethylene-1-decene, preferably ethylene-1-octene copolymer. Meka et al WO 93/03093 published February 18, 1993, the disclosure of which is incorporated herein by reference, discloses metallocene polymers useful for producing sealed articles, comprising ethylene interpolymers having a CDBI of at least 50% and a narrow molecular weight distribution or a mixture of polymers comprising a plurality of ethylene interpolymers as mixed components. There are commercially available metallocene / Zeigler-Natta (ZN) hybrid interpolymers of ethylene and alpha-olefins of CC? Or that offer up to the right combination of appropriate improvements to increase the performance of liquid bags compared to those made with conventional ZN-LLDPE or pure metallocene interpolymers. For example by selecting the correct resin parameters, it is possible to increase the roughness characteristics of the film such as fast impact strength and puncture resistance, and at the same time provide improved hot tack resistance and melt strength . These new hybrid interpolymers provide superior resins that can be used to produce films with increased strength characteristics such as fast-moving impact resistance and puncture resistance., and at the same time, these films exhibit improved hot tack resistance and melt strength. These improvements are evident particularly in monolayer films, but multi-layer films also possess such improvements. These improved characteristics are of particularly positive value since they mean that the processing of the resins in films and then in bags is considerably improved. This is of great significance since single site or pure metallocene catalyst resins have presented considerable processing problems, which have prevented them from becoming the resin / films of choice, particularly in the area of liquid bags. U.S. Patent No. 5,582,923 issued December 10, 1996 to Kate et al, all of the disclosures of which are incorporated herein by reference, discloses an ethylene polymer extrusion composition comprising from about 80 to 95 percent, weight of the total composition, of at least one ethylene / α-olefin interpolymer composition selected from the group consisting of a linear, homogeneously branched polymeric ethylene composition, and a linear, heterogeneously branched ethylene polymer composition, wherein the polymer of ethylene / α-olefin is characterized in that it has a density in the range of 0.85 g / cc to 0.940 g / cc and from about 5 to 20 weight percent, of the total composition, of at least one high pressure ethylene polymer characterized in that it has a melt index, 12, less than 6.0g / 10 minutes, density of at least 0.916 g / cc, a melt strength of at least 9 cN c As determined using a Goettfert Rheotens unit at 190 ° C, a ratio of Mw / Mn of at least 7.0 and a bimodal molecular weight distribution as determined by gel permeation chromatography, where the polymer extrusion composition of ethylene had a melt index, 12, of at least 1.0 g / 10 minutes.

BRIEF DESCRIPTION OF THE INVENTION It has now been found that commercially available hybrid interpolymers can be modified and refined to provide films of improved melt strength, in addition to optimizing other properties required for a bag film. As a result, the films can be produced which can be used to make pouches that demonstrate superior sealing properties that provide significant commercial advantages. The present invention provides in one aspect a bag for containing a fluid material, the bag is made of a tubular shaped film and having hot-sealed ends transversely, the film is made of at least one layer of a material comprising approximately 50 a roughly 100 parts by weight of a hybrid interpolymer of ethylene and a C3-C2 alpha olefin made by a polymerization process using a metallocene catalyst and a Zeigler-Natta catalyst, the hybrid interpolymer having a density of about 0.910 to about 0.940 g / cm3, a melt index from about 0.1 to about 2.0 dg / min, and from 0 to about 50 parts by weight of a high pressure polyethylene having a density from about 0.916 to approximately 0.924 g / cm and a melting index from approximately 0.1 to approximately 10 dg / min, the film has a resistance the melt greater than about 3.5 cN as determined using a Goettfer Rheotens unit at 190 ° C.

Preferably the melt strength of the film can vary from about 5 to about 20 cN, and more preferably from about 7 to about 15 cN. The film used to make the pouch of this invention may be a monolayer or a multilayer film. The patents referred to above provide many examples of suitable multilayer structures which can be used to make the bags of the present invention. In a preferred form of the invention, a bag formed of a film material is provided which comprises from about 80 to about 100 parts by weight of the hybrid interpolymer and from 0 to about 20 parts by weight of the pressure polyethylene. elevated The film material may also comprise about 90 parts by weight of the hybrid interpolymer and about 10 parts by weight of the high pressure polyethylene. In yet another form of the invention, a bag is provided wherein the hybrid interpolymer has a density from about 0.915 to about 0.930 g / cm3 and a melt index from about .1 to about 1.0 dg./min. Most preferably, the density of the hybrid interpolymer is about 0.920. g / cm3 and the melting index is approximately .5 dg./min. In another preferred form of the invention, the bag can be made of a film comprising a hybrid interpolymer obtained from a multiple polymerization process. The process may comprise at least two reactors in series or in parallel or both, with each reactor having at least one catalyst selected from metallocene catalysts and at least one catalyst selected from Zeigler-Natta catalysts, and the process uses both types of catalysts, one in each reactor. Alternatively, both types of catalysts can be used in a single reactor. The process can be followed to produce the fractions in weight of polymers according to methods known in the art. In the present example, the polymer resins produced can preferably comprise from about 20 to about 80% by weight of polymer derived from the metallocene catalyst and from about 80 to about 20% by weight of the polymer derived from the Zeigler-Natta catalyst. Most preferably the mixture of the fractions by weight may comprise from about 40 to about 60% by weight polymer derived from Zeigler-Natta catalyst with from about 60 to about 40% by weight of polymer derived from Zeigler-Natta catalyst. Most preferably, the ratio is about 50: 50% by weight. In another preferred form of the invention, the α-olefin for the interpolymer is selected from the group consisting of 1-propylene, 1-butene, 1-isobutylene, 1-hexene, 4-methyl-1-pentene, 1-pentene , 1-heptene and 1-octene. In another aspect, the invention provides a process for producing a bag containing a fluid material using a filling and sealing machine, in a vertical fashion, in this process each bag is made of a thin film web forming a tubular film 5 starting from this with a longitudinal seal and subsequently straightening the tubular film to a first position and heat sealing transversely of the tubular film in the untapped position, straightening the tubular film anterior to the predetermined amount of fluid material in a second position, the improvement comprises making the bags from a film having at least one layer of a material comprising from about 50 to about 100 parts of a hybrid interpolymer of 5 ethylene and a C3-C2 alpha olefin made for a process - ^? ^^ É? The polymerization using both a metallocene catalyst and a Zeigler-Natta catalyst, the hybrid interpolymer has a density from about 0.910 to about 0.940 g / cm, a melt index from about 0.1 to about 2.0 dg / min, and a melt strength greater than about 3.5 cN as determined using a Goettfert Rheotens unit at 190 ° C, and from about 0 to about 50 parts by weight of a high pressure polyethylene having a density of approximately 0.916 to approximately 0.924 g / cm and a melting index from approximately 0.1 to approximately 10 dg / min. The preferred type of equipment is that which produces a fusion through the seal and this seal is preferably provided by means of impulse sealing. It is possible to use the film of this invention as a sealing film or as a component in a more complex multilayer structure. Typical structures are those known in the art and which will follow the packaging application and allow the benefits of the improved sealing properties of the metallocene layer or SSC to be taken as advantages in the structure.

The patents and applications previously referred to describe the various processes that can be used to manufacture the bags of this invention. The apparatus of vertical form, filling and sealing is used to make the bags shown here. A flat film web is unwound from a roller and formed into a continuous tube in a section forming a tube by sealing the longitudinal edges together to be a lid seal or a final seal. This tube is pushed vertically towards a filling station and then collapses through a cross section of the tube, the position of this section coincides with a sealing device below a filling station. A transverse heat seal is made in the section that provides airtight seal to the air and liquid through a tube. The material to be packed enters the tube above the transverse seal, the tube falls at a predetermined distance under the influence of gravity on its charge. The sealing device opens again, and a second transverse seal is made in conjunction with a cut through the tube and frequently through the material placed in the bag. Thus, in this operation, the bag which has an elongated cushion shape is formed, filled and sealed in a rapid sequence of steps. Many variations of this process are possible and are obvious to those skilled in the art. Examples of typical liquid packaging apparatus used for this type of fabrication are made by Hayssen, Thimonier and Prepac. The term "fluid materials" as used herein encompasses materials that flow under gravity or which may be pumped. Gaseous materials are not included in this definition. Fluid materials include liquids, for example, milk, water, fruit juice and oil; emulsions, for example, mixture of ice cream cream and soft margarine; pasta, for example, pasta for food and peanut butter; preserves, for example, jams, pie fillers, jam, jellies and pasta; ground foods, for example, sausage food, powders, for example, powders for gelatin and detergents; granular solids, for example, nuts, sugar and similar materials. The bag of the present invention is particularly useful for liquids, for example, milk. The resins used to make the film of this invention are preferably extruded in known forms, although other suitable methods can be used, such as those involving laminates, coatings and the like. When the mixtures are used, these can be done by mixing the components prior to or at the same time of the extrusion until before remelting in the extruder. A film extruder can be used and the film is made using known techniques. An example of a process for film-by-blow form is found in Canadian Patent No. 460,963 issued November 8, 1949 by Fuller. Canadian Patent No. 893,216 issued Feb. 15, 1972 to Bunga et al, discloses a preferred method using an external and internal cooling mandrel in the film-by-blow process. The additives, known to those skilled in the art, such as antiblocking agents, slip additives, antioxidants, UV stabilizers, pigments and processing aids can be added to the polymers from which the bags of the present invention are made. . Typically, this may comprise up to 5% by weight of total resin components. As previously indicated, when additional additives and other components reach this ratio, it is important that they are sensitive to the improvement of the desired hot softening strength for the structure. As previously stated, the film of this invention can be used in packaging applications where the sealing properties, particularly the resistance to heat softening, are important. Reference may be made to The Wiley Encyclopaedia of Packaging Technology, 1986, John Wiley & Sons, Inc., under the Hot Sealing of the Top, the descriptions of which are incorporated herein by reference. Descriptions are found here for all types of hot sealing including bar seal, band, impulse, wire or wedge, ultrasonic friction, gas, contact, hot melt, pneumatic, dielectric, magnetic, induction, radiant and solvent sealing . Any of these techniques that provide by itself the packaging of materials incorporating the film of this invention fall within the scope of this description. The most preferred packages are made by impulse sealing.

DETAILED DESCRIPTION OF THE INVENTION MEASUREMENT OF FUSION RESISTANCE Determinations of melt strength are made at 190 ° C using a Goettfert Rheotens rheometer and an Instron capillary rheometer. The capillary rheometer is aligned and located above the Rheotens unit and a filament of fusion polymer is supplied to the Rheotens unit at a constant piston velocity of 25.4 mm / min. The Instron is equipped with a standard 2.1 mm diameter and 42 mm long (20: 1 L / D) capillary die. The Instron supplies the filament to the toothed compensation wheels of the Rheotens unit that rotate at 10 mm / s. The distance between the outlet of the Instron capillary die and the retention point on the Rheotens compensation wheels is 100 mm. The experiment to determine the resistance to fusion that comes about by accelerating the compensation wheels in the Rheotens unit to 2.4 mm / s, the Rheotens unit is capable of acceleration ranges from 0.12 to 120 mm / s. As the speed of the Rheotens compensation wheels increases with time, the downward direction force is recorded in centiNewtons (cN) using the Linear Variable Offset Translator (LVDT) in the Rheotens unit. The computerized data acquisition system of the Rheotens unit records the downward force plotted as a speed function of the compensation wheel. The actual fusion resistance value is taken from the plate of the plotted downward force, recorded. The speed at the filament break is also recorded in mm / s as the melt strength breaking speed. An example of a commercially available resin which can be modified to produce the bag film according to this invention is the Dow series of reams of the ELITE TM Brand.

EXAMPLE 5 A week-long field bag packing test with milk was conducted to compare the performance of the SCLAIR® SM3 film packing for Octene LLDPE milk bags and a film made of Ethylene-Octene Copolymer Hybrid of Metallocene - Zeigler Natta, identified by the designation of Film "A". The test was conducted in a dairy that drives two Prepac IS6 milk bag packaging machines that are identical and operate side by side in the dairy. This allows a line to operate using the SM3 film and the parallel line to operate using the new Metallocene-Zeigler Natta Hybrid copolymer film designated Film "A". The coding data in the packaging of milk were color coded to allow the identification of the line from which a packing is produced that rotates again and the production data. The milk product distributed a lot of its milk through the storage exits of the dairy along with some regular supermarkets. Any packaging with ^^^^^^^ S ^^. ^ ^ ^ ^ ^ ^ ^ ^ 1 The leak or damage was returned from the outlet stores or supermarkets to the milk for credit. For this reason, a very high proportion of leaking packages are returned to the dairy. By examining all return packages from 5 trial days, (as identified by their code date and code date color) the cause and frequency of the leaks could be assigned to each of the tested test films. The cause and location of each leak was identified and classified into three categories: leaks horizontal seal, vertical seal leakage and physical damage caused by a puncture or cut. The leakage frequency is calculated for each category by 10,000 bags produced during the test period. This method of evaluation of the films is It is very laborious and time consuming but it is the best way to determine the comparative performance of movies since all failure modes are looked at. A film may have good sealing performance but may be more likely due to physical damage or vice versa. A common goal in the industry is to develop films that work well in all categories. In the past, the range of stock market failures has been used to predict performance, and while it is a good general indicator, the actual field performance is more definitive because that evaluates movies under all the disadvantages that they can cause leakage and not up to several impacts. For example, seal leaks can be caused by a sealing element that fails or during startup when seal components are heated, etc. Physical damage can be caused by abuse during distribution (transportation, loading and unloading, etc.), or packaging machinery used to push bags of milk into sacks and then into dairy boxes. In summary, this field trial was designed to evaluate films under the actual conditions of use, looking at the three main modes of failure. The two test lines were operated on the dairy using SM3 and Film "A" for a week of production. During the test week 183,456 bags of milk were produced, with each line producing approximately 91,700 bags of milk. All the packages returned since they were examined in the production period during a period of the following three weeks until no more leaks appeared from this period in the return to the dairy. The two test films were: 1) SM3, the milk bag film for dairy, a standard that had been in commercial use for 10 years and is considered the film available for higher performance or performance milk.

It contains 85% Ethylene Octene LLDPE copolymer (Sclair 11IL4) and 15% High Pressure polyethylene. Sclair 11L4 contains adjuvant for sliding, antiblocking, and extrusion as part of its formulation. 2) Film "A" containing 85% ethylene copolymer Octene of Metallocene - Zeigler Natta. The film contains 10% high pressure polyethylene and approximately 5% additives including slip adjuvant, antiblock, and extrusion at narrow formulation levels to those of SM3. The following results were obtained from this field trial.

As you can see, the leak rate is improved in each category with the "A" film. All leaks were reduced by approximately 54% compared to SM3; Physical damage was reduced by 76% and seal leaks combined by 47%. It is clear that the hybrid copolymer provides a completely new balance of properties for this end use that transforms into a dramatic improvement in field operation. The invention can be varied in any number of ways as would be apparent to a person skilled in the art and all obvious and similar equivalents are understood to fall within the scope of this description and claims. The description is understood to serve as a guide to interpret the claims and not to limit them unnecessarily. It is noted that in relation to this date the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, the content of the following is claimed as property

Claims (18)

1. A bag for containing a fluid material, the bag is characterized in that it comprises a tubular shaped film and having transversely hot-sealed ends, the film comprises at least one layer of a material comprising from about 50 to about 100 parts. of an interpolymer of ethylene and an alpha-olefin of C3-C2o obtained by a The polymerization process using both a metallocene catalyst and a Zeigler-Natta catalyst in separate reactions, the interpolymer has a density of about 0.910 to about 0.940 g / cm, a melt index of about 0.1 to 15 about 2.0 dg / min, and from about 0 to 50 parts by weight of a high pressure polyethylene having a density from about 0.916 to about 0.924 g / cm3 and a melt index from about 0.01 to about 10. dg / min, and the The film had a melt strength greater than about 3.5 cN as determined using a Goettfert Rheotens unit at 190 ° C. • - * a ^ ^^

2. The bag according to claim 1, characterized in that the film is a monolayer film.

3. The bag according to claim 1, characterized in that the film is a multilayer film.

4. The bag according to claim 1, characterized in that the film comprises from about 80 to about 100 parts by weight of the interpolymer and from 0 to about 20 parts by weight of the high pressure polyethylene.

5. The bag in accordance with the claim 1, characterized in that the film comprises approximately 90 parts by weight of the interpolymer and approximately 10 parts by weight of the high pressure polyethylene.

6. The bag according to claim 1, characterized in that the melting strength of the film is from about 5 to about 20 cN.

7. The bag according to claim 1, characterized in that the melting strength of the film is from about 7 to 15 cN.

8. The bag according to claim 7, characterized in that the hybrid interpolymer had a density from about 0.915 to about 0.930 g / cm, a melt index from about .1 to about 1.0 dg / min.

9. The bag according to claim 7, characterized in that the interpolymer had a density of 0.920 g / cm, the melt index is .5 dg./min.

10. The bag according to claim 1, characterized in that the α-olefin used in the interpolymer is selected from the group consisting of 1-propylene, 1-butene, 1-isobutylene, 1-hexene, 4-methyl-1-pentene, 1-heptene and 1-octene.

11. The bag according to claim 1, characterized in that the film comprises an interpolymer obtained from a polymerization process of multiple reactors comprising at least two reactors in series or in parallel, with each reactor having at least one catalyst selected from catalysts of metallocene and / or at least one catalyst selected from Zeigler-Natta catalysts and the process uses both types of catalysts.

12. The bag according to claim 11, characterized in that the weight fractions of the polymer resin comprise from about 20 to about 80% by weight of polymer derived from metallocene catalyst and from about 80 to about 20% by weight of polymer derived from Zeigler-Natta catalyst.

13. The bag according to claim 12, characterized in that the weight fractions of the polymer resin comprise from about 40 to about 60% by weight of polymer derived from the metallocene catalyst and from about 60 to about 40% by weight of polymer derived from the Zeigler-Natta catalyst.

14. The bag according to claim 11, characterized in that the weight fractions of the polymer resin comprise from about 50: 50% by weight.

15. The bag according to claim 1, characterized in that the interpolymer comprises 85% by weight and the high density low density polyethylene and the processing additives comprise 15% by weight.

16. The bag according to claim 15, characterized in that the interpolymer comprises ethylene octene interpolymer. '# * > J ^ S ^ S &t ^ J ^^^^^^

17. A process for producing a bag containing a fluid material using a vertical, filled and sealed apparatus, in this process each bag is made of a flat weft of film forming a tubular film therefrom with a longitudinal seal, and subsequently crushing the tubular film in a first position and transversely heat sealing the tubular film in the collapsed position, and then collapsing the tubular film above the amount predetermined fluid material in a second position, the improvement comprises making pouches of a film comprising at least one layer of a material comprising from about 50 to about 100 parts of an interpolymer of ethylene and an alpha-olefin of C3- C20 made by a polymerization process using both a metallocene catalyst and a Zeigler-Natta catalyst in separate reactions, the interpolymer has a density from about 0.910 to about 0.940 g / cpi3, a melt index from about 0.1 to about 2.0 dg / min, and from about 0 to about 50 parts by weight of a high pressure polyethylene having a density from about 0.916 g / cm3 and a melt index from about 0.1 to about 10 dg / min, and the film had a melt strength greater than 3.5 cN as determined using a Goettfert Rheotens unit at 190 ° C.

18. The process according to claim 17, characterized in that the transverse seal comprises a fusion through the seal by means of impulse sealing. MOVIE BAGS OF HYBRID INTERPOLIMEROS n RESUME PE THE INVENTION A bag for containing a fluid material, the bag is made of a tubular shaped film and having transversely hot sealing ends, the film is made of at least one layer - from a material comprising approximately 50 to approximately 100 parts by weight of a hybrid interpolymer of ethylene and a C3-C20 alpha-olefin made by a process of By polymerization using both a metallocene catalyst and a Zeigler-Natta catalyst, the hybrid interpolymer has a density from about 0.910 to about 0.940 g / cm, a melt index from about 0.1 to 2.0 dg / min, and a resistance to the 15 melt greater than about 3.5 CentiNewtons as determined using a Goettfert Rheotens unit at 190 ° C and from 0 to about 50 parts by weight of a high pressure polyethylene having a density from about 0.916 to about 0.924. 20 g / cm 3 and a melt index from approximately 0.01 to approximately 10 dg / mm. A process for producing such bags is also described. 25 - ^^: ^^^^ lmB S? Ml ^^ 9 ^ ^? Éc ^^ S ^ i ^ ltt