MX2008008301A - Calcium carbonate barrier films and uses thereof - Google Patents

Abstract

The present invention provides polyolefin films comprising calcium carbonate that have a reduced moisture vapor transmission rate, methods of making the films, and packaging materials comprising the films.

Description

CALCIUM CARBONATE BARRIER FILMS AND USES OF THE SAME CROSS REFERENCE TO RELATED REQUESTS This application claims the benefit of the Patent Application Provisional of the United States of America No. 60 / 755,659, filed December 29, 2005, the content of which is incorporated herein by reference.

FIELD OF THE INVENTION This invention is directed to a film structure comprising polyolefin and calcium carbonate having reduced moisture vapor transmission rate and is suitable for packaging moisture sensitive materials such as dehydrated foods, animal feed, and pharmaceuticals.

BACKGROUND OF THE INVENTION Throughout this application, several publications are referred to in parentheses. Full citations of those references can be found at the end of the specification immediately before the claims. The descriptions of these publications are incorporated herein by reference in their entirety within the application in question to describe more fully the technique to which the application in question belongs. To pack dehydrated foods and other moisture-sensitive materials, it is desirable to have a barrier packaging that prevents the ingress of wet steam and thus prevents the contents from getting wet. The packaging will allow the food material to be placed in containers inside a cardboard box for shelf display and ease of handling. Polymer films have been developed with the aim of increasing rather than decreasing the transmission of wet vapor through the film (e.g., International Application Publications TCP Nos. WO 02/10275 A2, 03/020513 A1 and WO 03 / 031134 A1). In contrast, the reduced water vapor transmission rate (WVTR) has been achieved using a laminated paperboard substrate, which is suitable as a beverage container. (U.S. Patent Application Publication No. 2004/0105942). Reduced WVTRs have also been obtained by targeting high density polyethylene (HDPE) films (U.S. Patent Nos. 4,183,893, 4,870,122, 6,391, 411). While there are different technologies that provide a wet vapor barrier in packaging films, there is a need for improved barrier films for packaging dehydrated foods and other moisture sensitive material wherein the film is both moisture resistant and economical.

BRIEF DESCRIPTION OF THE INVENTION The present invention meets this need by using calcium carbonate (CaCO3) to provide improved polyolefin barrier films. The barrier film achieves good resistance to wet steam, heat sealing and handling properties. The barrier structure is comprised of a calcium carbonate containing polyolefin film in a single or multiple layer film construction. In structures having a plurality of film barrier layers comprising CaCO3, CaCO3 provides in each of the multiple barrier layers a reduced rate of transmission of wet vapor through the respective barrier layers. The films are especially useful in food packaging, animal feed packaging, pharmaceutical packaging, and packaging of other moisture sensitive materials. Additional objects of the invention will be violent from the following description.

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to films comprising polyolefin and calcium carbonate, wherein the films have a reduced moisture vapor transmission rate (MVTR). Polyolefins are a family of polymers made from of olefin monomers. Examples include polyethylene (PE), polypropylene and polyisoprene. PE can be high density PE (HDPE, density >; 0.95 gm / cm3), medium density PE (MDPE, density 0.934 to <0.95 gm / cm3) and low density PE (LDPE, density <0.934 gm / cm3). LDPE can be linear LDPE (LLDPE). HDPE is a preferred polyolefin. Medium molecular weight HDPE (MMW-HDPE) is a preferred HDPE. As used herein, polymers of average molecular weight (MMW) have the following weight distributions: number average molecular weight (Mn) of 6,000 to 13,000, weight average molecular weight (Mw) of 50,000 to 120,000, and Z average molecular weight (Mz) from 175,000 to 500,000. Preferably, the number average molecular weight (Mn) is from 8,000 to 11,000. Preferably, the weight average molecular weight (Mw) is from 70,000 to 100,000. Preferably, the average molecular weight M (Mz) is 250,000 to 400,000. A preferred film comprises a) a polyolefin base resin and b) a polyolefin carrier resin mixed with calcium carbonate (CaCO3), wherein the CaC03 and a carrier resin are present in a ratio of 15/85 to 80/20 by weight . Preferably, a base resin and a carrier resin are different resins. A base resin and a carrier resin may differ, for example, in molecular weight, density, melt index, and / or polydispersity index. The polydispersity index is the weight average molecular weight (Mw) divided by the weight number average molecular (Mn). A carrier resin can have an Mw / Mn ratio of, for example, 6.82 and a base resin can have a ratio of, for example, 9.35. A carrier resin and a base resin can differ in Z average molecular weight (Mz) where, for example, a carrier resin has an Mz of 203,000 and a base resin has an Mz of 332,000. Another preferred film comprises polyolefin and calcium carbonate (CaCO3), wherein the film comprises: a) a polyolefin base resin having a melt index of 0.05-2.0 dg / min and a density of 0.958-0.963 g / cm3; b) a polyolefin carrier resin for CaCO3, wherein a carrier resin has a melt index of 4-10 dg / min and a density of 0.958-0.963 g / cm3; and c) CaCO3; wherein CaCO3 is present in the film in a total concentration of 5% -35% by weight. A further preferred film comprises: a) a high density polyethylene (HDPE) base resin, wherein a HDPE base resin has a melt index of 0.05-2.0 dg / min and a density of 0.958-0.963 g / cm3; b) a HDPE carrier resin for calcium carbonate (CaCO3), wherein a HDPE carrier resin has a melt index of 4-10 dg / min and a density of 0.958-0.963 g / cm3; and c) CaCO3, wherein the CaCO3 has an average particle size of 0.7-2.5 μ, a top cut d98 of 4-15 μm, a surface area of 3.3-10.0 mVg, and a total concentration in the film of 5-35% by weight, wherein CaCO3 has been treated with a surface treatment agent at a treatment level of 0. 3-2.3% by weight, and wherein CaCO3 and an HDPE carrier resin are present in a ratio of 15/85 to 80/20 by weight. Preferably, CaCO3 has been treated with the surface treatment agent at a treatment level of 1.5-3 mg surface treatment agent / m2 of CaC03. Preferably, CaCO3 has been wet milled and / or dry milled prior to the incorporation of CaC03 into the film. The wet grinding can be carried out in the absence of a grinding aid or in the presence of a grinding aid comprising, for example, a salt of polyacrylic acid and / or a salt of a copolymer of acrylic acid. Preferably, the calcium carbonate is dried after grinding. The CaCO3 can be treated with the surface treatment agent before and / or during and / or after the grinding of CaCO3. Another preferred film comprises a) a high density polyethylene (HDPE) having a density of 0.958-0.963 g / cm3, and b) calcium carbonate (CaC03) having an average particle size of 0.7-2.5 μ? T? , a top cut d98 of 4-15 pm, a surface area of 3.3-10.0 mVg, and a total film concentration of 5-35% by weight. CaCO3 and a carrier resin can be present in the films in a ratio of 15/85 to 80/20 by weight, for example 40/60 to 80/20 by weight. Preferred ranges of CaCO3 / carrier resin ratios are 15/85 less than or equal to (=) 60/40 by weight, eg 40/60 to < 60/40 in weight and 45/55 to 55/45 in weigh. In a more preferred film, CaCO3 and a carrier resin are present in a ratio of 50/50 by weight. CaC03 may be present in the films in a total concentration, for example, of 5% -35% by weight, preferably 20% -30% by weight, and more preferably 25% by weight. These concentrations apply to both single-layer films and multi-layer films, wherein some layers may not contain CaC03 at all or where different layers may contain different amounts of CaCC > 3. A base resin of the present invention can have a melt index, for example, 0.05-2.0 dg / min, preferably 1 dg / min. A base resin can have a density of 0.958-0.963 g / cm3, preferably 0.962 g / cm3. Preferably, a base resin is a high density polyethylene (HDPE). Preferably, HDPE is a medium density high molecular weight polyethylene (MMW-HDPE). Base resins such as MMW-HDPE resins can be produced through Zigler-Natta catalyst chemistries and generally fall within the range of 0.85 to 1.5 dg / min melt index, and densities of 0.9580 g / cm3 and above to the maximum limits for polyethylene manufactured without co-monomers. A preferred base resin is a resin having the properties of Resin A (see Table 1, below). In traditional applications, the films can be made by extruding this material, or similar material in its pure form (without any other additive or mixtures teachers). As used in the present, this material is referred to as a "base resin." The carrier resin for CaCO3 can have a melt index of 4-10 dg / min, preferably 6.5-8. Q dg / min, and most preferably 6.5 dg / min. The carrier resin can have a density, for example, of 0.958-0.963 g / cm3, preferably 0.962 g / cm3. Preferably, the carrier resin is a high density polyethylene (HDPE). Preferably, the HDPE is a medium density high molecular weight polyethylene (MMW-HDPE). The CaCO3 in the films can have an average particle size of 0.7-2.5 pm, preferably 1.4-2.0 pm, and most preferably 1.4 pm. CaCO3 may have a top cut d98 of 4-15 pm, preferably 8-10 pm, and most preferably 8 pm. The upper cut d98 refers to the average diameter of calcium carbonate particles in the percentage mass 98a. The CaCO3 may have a surface area of 3.3-10.0 m2 / g, preferably 3.3-5.5 m2 / g, and more preferably 5.5 m2 / g. The calcium carbonate may be natural ground calcium carbonate such as, for example, ground marble, limestone or chalk, and / or a precipitated calcium carbonate (eg, aragonite, waterite or calcite). Preferably, calcium carbonate is a natural ground calcium carbonate. Calcium carbonate can be milled dry and / or wet milled. Wet grinding refers to grinding calcium carbonate in a liquid medium. The ground wet can be carried out in the absence of a grinding aid or in the presence of a grinding aid. One or more auxiliary grinding agents may be included, such as, for example, sodium polyacrylate, a salt of polyacrylic acid, and / or a salt of a copolymer of acrylic acid. For example, calcium carbonate can be derived from marble, which is finely ground in an aqueous medium with a high solids content using dispersion aids in order to keep the particles suspended during the process. The material is then dried, dried, treated and deagglomerated to finely divide the individual particles again. Drying can take place using any suitable drying equipment and can, for example, include thermal drying and / or drying under reduced pressure using equipment such as an oven, a spray drier (such as spray drier sold by Niro and / or Nara), and / or drying in a vacuum chamber. Drying can be batch and / or continuous. Surface treatment agents can be added to CaCO3 to facilitate the dispersion of CaCO3 in the resin. The surface treatment agents can be, for example, one or more fatty acids having from 8 to 24 carbon atoms. These agents include, for example, one or more of arachidic acid, behenic acid, capric acid, ceric acid, isostearic acid, lauric acid, myristic acid, montanic acid, palmitic acid and stearic acid. Preferred treatment agents include acid stearic and a mixture of stearic acid and palmitic acid. The fatty acid can be in the form of a vegetable source. The fatty acid can be kosher. CaCO3 can be treated with the surface treatment agent at a treatment level of 0.3-2.3% by weight of the treatment agent and 97.7-99.7% by weight CaCO3. Preferably, the treatment level is 0.8-1.1% by weight of the treatment agent (89.9% -99.2% by weight CaCO3), and more preferably 1.1% by weight of the treatment agent (89.9% by weight CaCO3) . Preferably, the treatment level is 1.5-3.0 mg of surface treatment agent per m2 of CaCO3, more preferably 2-2.4 mg agent / m2 CaCO3. For ground CaC03, CaC03 can be treated with the surface treatment agent before and / or during and / or after grinding of CaCO3. The construction of wet vapor barrier packaging films is mono or multi-layer. The present invention is also directed to multilayer films comprising any of the polyolefin and calcium carbonate films described herein. Multi-layer films usually use an internal contact layer to promote sealing, wherein the inner contact layer comprises one or more ethylene vinyl acetate (EVA), ethylene ethyl acetate (EEA), and ethylene acrylic acid (EAA). The content of vinyl acetate in this contact layer resin is commonly about 18% by weight. Depending on the extruder configuration in a coextrusion process, there may be from 2 to 7 or more layers.

A preferred multi-layer film comprises an inner layer comprising one or more of ethylene vinyl acetate (EVA), ethylene ethyl acetate (EEA), and ethylene acid (EAA), a core layer comprising polyolefin and calcium carbonate (CaCO3) ), and an outer layer comprising polyolefin and calcium carbonate (C to CO 3). As used herein, the terms "internal", "central" and "external" are used to describe and clarify the relative position of several layers in a multi-layer film construction. The term "internal" refers to the surface of a packaging film that comes into contact with the contained product; while, the term "external" refers to the exterior of the packaging film that is in contact with the surrounding atmosphere. "Central" describes the layer intercalated effectively between the outer and inner layers. The multilayer film can have a weight distribution per layer, for example, 25-35% outer layer, 50-60% core layer, and 10-20% inner layer, for example 30% outer layer, % central layer, and 15% internal layer. [25] The concentration of ethylene vinyl acetate (EVA), ethylene ethyl acetate (EEA). or ethylene acrylic acid (EAA) in the film layer containing EVA, EEA or EAA can be, for example, 15-20% by weight. Ethylene vinyl acetate (EVA) can have a density, for example, of 0.95 g / cm 3. Ethylene vinyl acetate (EVA) can have a melt index, for example, of 1.5 dg / min. Another multilayer film comprises at least one first layer containing one or more of ethylene vinyl acetate (EVA), ethylene ethyl acetate (EEA), and ethylene acrylic acid (EAA) and at least a second layer containing polyolefin and calcium carbonate (CaC03), wherein CaCO3 is present in the multilayer film in a total concentration of 5% -35% by weight, preferably 20% -30% by weight, and more preferably 25% by weight. The invention also provides methods for making masterbatch compositions for preparing the films, wherein the methods comprise mixing any of the CaCO3 and polyolefin carrier resins described herein. In itself, calcium carbonate is a finely divided powder and can be difficult to handle, dose and feed an extrusion system. To facilitate the introduction of finely ground ore to the extrusion process, a pellet master mix can be produced from the selected polyolefin resin (s) (eg, polyethylene) and calcium carbonate (s). ). The master pellet mixes contain calcium carbonate and the "carrier resin" to bind to the pellet. A small amount of antioxidant is added in a common way in order to avoid degradation of the polymer. A preferred method comprises mixing CaCO3 with a polyolefin carrier resin, wherein CaC03 and a carrier resin are present in a ratio of 15/85 to 80/20 by weight, more preferably 15/85 to < 60/40 in weight. Another preferred method comprises mixing CaCO3 with a carrier resin of HDPE, wherein the CaCO3 and the HDPE carrier resin are present in a ratio of 15/85 to 80/20 by weight, more preferably 15/85 to < 60/40 in weight. The methods can include the formation of the master mix compositions in pellets. The invention provides master mix compositions prepared by any of the methods described herein. A preferred masterbatch composition, for example, comprises 50% by weight calcium carbonate of average particle size of 1.4 m diameter, a top cut particle size d98 of 8.0 μm, with 1.1 wt. surface of stearic acid, in 50% by weight of high density polyethylene carrier resin (HDPE) of 0.962 g / cm3 density and 6.5 dg / min of melt index. A treatment level of 1.1% by weight stearic acid represents 1.1% by weight stearic acid and 98.9% by weight calcium carbonate. The invention further provides methods for making a film comprising polyolefin and calcium carbonate (CaC03), wherein the method comprises mixing any of the master mix composition described herein with any of the polyolefin base resins described herein. Each of the master mix composition and a base resin can be in the form of pellets, which can be mixed in a desired ratio. The mixed pellets are melted and then extruded or spread on an intermediate film, which can be extended later to form a final film. The selection of a carrier resin is critical in determining the physical properties resulting from the film, especially at higher charge levels of CaCO3. As described in the present invention, it is advantageous to use a carrier resin that is different from a base resin in order to obtain the best production or quality efficiencies of the masterbatch, and / or the desired physical properties of the resulting extrudates. Preferred carrier resins are higher melt index (lower molecular weight) polyethylenes, which function to improve the MVTR barrier properties. A preferred carrier resin is one that has the properties of Resin B (see Table 1, below). An alternative to using the pellet master mix system to supply calcium is to use a fully formulated resin. In this case, a resin would be composed of the desired amount of calcium carbonate and formed into pell The pellwould then be added directly to an extruder to produce an extrudate of the desired type. Filmmaking methods can include co-extrusion of a film layer comprising polyolefin and calcium carbonate with a film layer comprising one or more of ethylene vinyl acetate (EVA), ethylene ethyl acetate (EEA), and acid Acrylic ethylene (EAA). For example, an inner film layer comprising one or more of ethylene vinyl acetate (EVA), acetate of ethylene ethyl (EEA), and ethylene acrylic acid (EAA) is coextruded with a central film layer comprising polyolefin and calcium carbonate (CaC03) and an outer film layer comprising polyolefin and calcium carbonate (CaC03). Coextrusion as a polymer material processing technique uses multiple extruders to feed a die block to combine multiple streams of polymer flow prior to the formation of the combined melt in a die. The advantage of using coextrusion is the ability to form well-bonded structures from multiple materials of variable properties in a single step. The production method by co-extrusion according to this invention can, for example, be carried out by driving two or more kinds of olefin resins, plasticized by means of two or more extruders, in a common die and causing them to enter contact inside or in the die opening to thereby form in the first stage a film with two or more layers. Preferably, the film is processed in an enlargement ratio (BUR) from 1.6: 1 to 2.2: 1, more preferably 1.6: 1. Preferably, the film is processed to a thousandth of an inch caliber of 2.0-3.0, more preferably 2.0-2.5. The invention provides films made through any of the methods described herein. The preferred calcium carbonate-polyolefin films of The present invention has a reduced moisture vapor transmission rate (MVTR) compared to the film in the absence of CaCO3. As used herein, the wet steam transmission rate (MVTR) and the water vapor transmission rate (WVTR) are used interchangeably. Preferably, the MVTR is reduced by 10-30% compared to the MVTR of the film in the absence of CaCO3. More preferably, the MVTR was reduced by 20-30% compared to the MVTR of the film in the absence of CaC03. Even more preferably, the MVTR is reduced by 25-30% compared to the MVTR of the film in the absence of CaCO3. The films may have a wet vapor transmission rate (MVTR) of, for example, 0.213-0.230 g water vapor -mil / 100 n2 film / day, more preferably 0.213 g water vapor -mil / 100 in2 film / day, at 37.5 ° C and 100% relative humidity. As used herein for MVTR values, the term "thousand" refers to the thickness of the film, where 1 thousand = 1 / 1,000 of a one-inch thick film. The invention provides packaging films comprising any of the films described herein. The films are especially useful in food packaging, packaged animal feed, pharmaceutical packaging, and packaging of other moisture sensitive materials. The food products may be dehydrated food products, such as cereal or biscuits. The reduced MVTR of The films described in the present aid prevent the entry of wet steam and therefore prevent the food contents from getting wet. The packaged film allows the food material to be placed in containers inside a cardboard box for shelf display and ease of handling. Films will be susceptible to a long product storage life in an effective cost-effective packaging that meets multiple performance needs. The films described herein may serve as freestanding films, which are not laminated to a support such as a cardboard substrate or other rigid support.

The present invention is illustrated in the following section of Experimental Details, which is established to aid in the understanding of the invention, and will not be considered as limiting in any way the scope of the invention as defined in the claims that are presented more ahead.

EXPERIMENTAL DETAILS Compendium To illustrate the properties of a polyolefin film having a calcium carbonate additive, a comparative study of a 3-layer MMW-HDPE film extruded with a similar construction incorporating 20-30 wt.% Calcium carbonate was compared. in the construction of total movie. Calcium carbonate it was contained only in the outer and central layers and not in the inner layer. Calcium carbonate was incorporated as a master mix of calcium carbonate. A three-layer film was coextruded using a MMW-HDPE base resin (Resin A in Table 1) having a density of 0.962 g / cm3 and a melt index of 1.0 dg / min for the outer and middle layers, with a layer internal ethylene vinyl acetate (EVA) (Dupont Evlax® 3169Z) with a density of 0.95 g / cm3, melt index of 1.5 dg / min and 18% by weight of vinyl acetate comonomer. The purpose of the EVA inner layer is to provide improved seal performance by allowing lower seal initiation temperatures and shorter seal dwell time in the bag forming process. The coextrusion layer distribution consisted of 30% outer layer, 55% central layer and 15% inner layer EVA by weight. The total mineral charge was directed to 25% by weight of calcium carbonate in most of the films (see Table 4 below); therefore, 29.5% by weight calcium carbonate was necessary in the outer and middle layers to form the effective amount. Correspondingly, the additive feed system was directed to 58.8% by weight of concentrated masterbatch and 41.2% by weight of MMW-HDPE (Resin A in Table 1) for the external and central layer extruders in order to obtain 29.5% by weight. % needed in these respective layers to match the effective amount of 25% by weight in the films.

The resulting films were evaluated for physical performance including wet steam transmission rate (MVTR) using a Mocon PERMATRAN-W® Model 3/33. When comparing standard films without calcium carbonate to 3.0 thousandths of an inch of extruded caliper at an expansion ratio of 1.6 against films extruded to a smaller caliber (2.5 mils) using 25% by weight extruded calcium carbonate at ratios of similar expansion, resulted in improvements in the MVTR as presented below. By being present the calcium carbonate in the outer film layer contributes to a surface hardening effect, which effectively facilitates the handling of the films in the secondary operation bag forming equipment and allows for easier recording capacity and printing and improved. It has also been shown that this surface modification by adding calcium carbonate reduces the coefficient of friction. While a preferred embodiment is made in reference to a co-extruded polyolefin film having approximately 25 wt.% Calcium carbonate filler, it is recognized that other relative percentages of calcium carbonate may be used in building forms of calcium carbonate. monolayer or multi-layer. By way of example, changing the construction layer distribution or the location of the calcium carbonate (calcium carbonate in the central layer only) would provide a structure having properties similar to the illustrative embodiment established Experimental Work Details Melt index, density and molecular weight measurements: The melt index was measured using the standard method ASTM D1238-04, Standard Test Method for Melt Flow Rates of Thermoplastics by Extrusion Plastometer. This standard can be found in the ASTM 2005 Annual Book of Standards, Section Eight - Plastics Volume 8.01. The density was measured using the standard method ASTM D1501 -03, Standard Test Method for Plastics Density by the Density Gradient Technique. This standard can be found in the ASTM 2005 Annual Book of Standards, Section Eight - Plastics Volume 8.01. The molecular weight was determined using a Waters gel permeation chromatograph. The pump used was a 150C operated at a flow rate of 1.00 mL / min at an injection volume of 250 pL at 135 ° C. The mixture was prepared using 12mg of polyethylene sample dissolved in 4mL of 1,2,4-Trichlorobenzene. The columns used were Waters Styragel HT3, HT4, HT5 and HT6E. The number average molecular weight (Mn), weight average molecular weight (Mw) and average molecular weight Z (Mz) were calculated as follows. The numerical average molecular weight (Mn) is the total weight of all the polymer molecules in a sample, divided by the total number of polymer molecules in the sample. Mn is expressed mathematically where Ni is equivalent to the particular number of molecules in a given molecular mass and Mi is the molar weight of the respective molecules. The weight-average molecular weight (Mw) is the next highest molecular weight expressed mathematically as where each molecule contributes to Mw in proportion to the square of its respective mass. The average molecular weight Z (Mz) is the next highest molecular weight for Mw and is expressed mathematically as where each molecule contributes to Mz in proportion to the cube of its respective mass.

Measurement of Humid Steam Transmission Speed: the evaluation of the wet vapor transmission speed (MVTR) of the films was carried out in a Mocon Permatxan-W Model 3/33. Samples were tested according to the ASTM standard, F1249-05 Standard Test Method for Water Vapor Transmission Rate through Plastic Film and Coating Using a Modulated Infrared Sensor, operated at 37.8 ° C and 100% relative humidity . This standard can be found in the ASTM 2005 Annual Book of Standards, Volume 15.09. Measurement of particle size distribution: the evaluation of particle size distribution (PSD) was performed by means of an X-ray sedimentation technique using a Sedigraph 5100, in accordance with ISO 13317-1 General Principles and Standards , and Gravitational X-Ray techniques 13317-3. Measurements were made using Sedigraph in the high speed analysis control mode using Tygon tubing with high flexural longevity. The sample was prepared in 0.2% by weight of sodium hexametaphosphate dispersant. A sample of 5.0 grams at 35 ° C was evaluated using an internal fixed position X-ray source / detector. The initial / final sample point diameters measured 50 -0.5 μ? T ?, respectively.

Equipment: Extruder: Battenfeld Gloucester co-ex extrusion, extruder internal 2", central extruder 3.5" (medium) and an external extruder 2". Layer ratio: A (internal) -30%, B (Central) -55%, and C (External) -I 5% Sieve Package: Mesh 20/80/20 Identical package configuration used in the three extruders Die: 8"Battenfeld Gloucester w / 80 thousand Air Ring die space. Egan Da vis-Standard double-lip Resins: Table 1. Resins Density in g / cm3, MI = melt index (dg / min), Mn = numerical average molecular weight, Mw = weight average molecular weight, Mz = z average molecular weight Resin D contains a fluoroelastomer polymer processing aid (a flow promoter) and showed a poor response with respect to MVTR.

Calcium Carbonate Minerals: Table 2. Calcium Carbonate Minerals Upper cut d98 refers to the average diameter of calcium carbonate particles in the mass percentage 98 °. the level of treatment refers to the surface treatment of CaCO3 with a mixture of stearic acid / palmitic acid.

Process: Air Ring: Cooling temperature 52-54 ° F with a pressure of 3.5 inches (psig). Freezing Line: Height range - 18 to 19 inches Output Speed: Constant at 250 # / hr. Conditions: Enlargement Combinations (BUR) and gauge (thickness measured in thousandths of an inch).

Table 3. Processing Conditions BUR = Enlargement Ratio.

Samples: Table 4. Samples The description of types of Resin and Calcium Carbonate (CC) in Master Mix is found in Tables 1 and 2, respectively.

Test Notes: Nine samples including one control and five different master mixes of calcium carbonate were extruded in a Gloucester Battenfeld coextrusion film line. Except for samples A and C, each of these samples were extruded in four different conditions (caliber 2.0 and 2.5, and magnification ratio 1.6 and 2.2). Samples A & C were processed only in the 2.5 mil caliber with the magnification ratio of 1.6 and 2.2, respectively. Conditions 5 and 6 (Table 3) were only used for the controls.

Results and Discussion The objective of the evaluation was to determine which set of extrusion and calcium carbonate concentrate combinations provided the highest resistance to the wet steam transmission speed. It was demonstrated that a film made from Resin A with 25% by weight of calcium carbonate incorporated through a 50/50 master mix of Resin B or C (Table 1) with calcium carbonate (CC) type A ( Table 2) proportion the most appropriate improvements for MVTR when processed in the 1.6 magnification ratio and 2.5 mil. Table 5A-C summarizes the film performance, including the response to the wet vapor transmission rate (MVTR). The codes in Table 5A-C for the Samples and Process Conditions are found in Tables 3 and 4. The films described herein provide a cost-efficient means, compared for example with the use of metallized films, to provide films with reduced MVTRs that can be used for packaging of moisture sensitive products such as dehydrated foods.

Table 5A. Film Performance Results (continued in Table 5B &5C) Table 5B. Film Performance Results (continuation of Table 5A) Table 5C. Film Performance Results (continuation of Table 5a &5B) Notes for Table 5B: "MVTR" is the original MVTR. "nMVTR" is the MVTR corrected using the measured gauge. "nMVTR (2)" is the corrected MVTR using the target caliber. "Effect of CaC03" shows the improvement in MVTR (corrected measured caliper) against control film in the same caliber and film orientation (BUR) "BUR effect" shows the improvement in MVTR resulting from BUR with a load of CaC03 and equivalent caliber. Positive numbers indicate an improvement (ie, reduced MVTR); Negative numbers indicate a deficiency. Notes for Table 5C: The comparison in Column 3 is between a 2.5 mil film containing CaC03 versus a 3.0 mil straight HDPE in equivalent BUR. "Improved nMVTR Average" in Column 4 is the average improvement in MVTR of CaC03 that contains samples against control a in a given BUR. "Improvement nMVTR Average" in Column 5 is the average improvement in nMVTR of samples containing CaC03 against the control through both calibers and BURs used. Positive numbers indicate an improvement (ie, reduced MVTR); Negative numbers indicate a deficiency.

REFERENCES International Publication TCP No. WO 02/10275 A2, published on February 7, 2002, Eastman Chemical Company. International Publication TCP No. WO 03/020513 A1, published March 13, 2003, Kimberly-Clark Worldwide, Inc. International Publication TCP No. WO 03/031134 A1, published April 17, 2003, Imerys Minerals Limited. Patent Application Publication of the United States of America No. 2004/0105942 A1, published June 3, 2004.

U.S. Patent No. 4,183,893, published January 15, 1980. U.S. Patent No. 4,870,122, issued September 26, 1989. U.S. Patent No. 6,391, 411 B1, published on May 21, 2002.

Claims (33)

1. A film comprising: a) a polyolefin base resin; and b) a polyolefin carrier resin mixed with CaCO3; wherein the CaCO3 and a carrier resin are present in a ratio of 15/85 to 80/20 by weight.

2. The film according to claim 1, characterized in that the base resin and the carrier resin are different resins and, preferably, in molecular weight, density, melt index and / or scatter index.

3. The film according to any of claims 1 to 2, characterized in that the carrier resin has a melt index of 4-10 dg / min.

4. The film according to any of claims 1 to 3, characterized in that the carrier resin has a density of 0.958-0.963 g / cm3.

5. The film according to any of claims 1 to 4, characterized in that the CaCO3 is present in the film in a total concentration of 5% -35% by weight.

6. A film comprising: a) a polyolefin base resin having a melt index of 0.05-2.0 dg / min and a density of 0.958-0.963 g / cm3; b) a polyolefin carrier resin for CaCO3, where the carrier resin has a melt index of 4-10 dg / min and a density of 0.958-0.963 g / cm3; and c) CaCO3; wherein the CaCO3 is present in the film in a total concentration of 5% -35% by weight.

7. The film according to any of claims 1 to 6, characterized in that the CaCO3 and the carrier resin are present in a ratio of 15/85 to 80/20 by weight.

8. A multilayer film, wherein at least one first layer of the multilayer film comprises one or more of ethylene vinyl acetate (EVA), ethylene ethyl acetate (EEA), and ethylene acrylic acid (EAA), and at least one second layer of the multilayer film comprises polyolefin and calcium carbonate (CaCO3), and wherein CaC03 is present in the multilayer film at a concentration of 5% -35% by weight.

9. The multilayer film according to claim 8, characterized in that the film layers comprising polyolefin and calcium carbonate (CaCO3) comprise a polyolefin carrier resin and wherein the CaCO3 and the polyolefin carrier resin are present in a ratio from 15/85 to 80/20 by weight, and optionally the polyolefin carrier resin has a melt index of 4-10 dg / min.

10. A film comprising: a) a high density polyethylene base resin (HDPE), where the HDPE base resin has a melt index of 0.05 - 2.0 dg / min and a density of 0.958-0.963 g / cm3; b) a HDPE carrier resin for calcium carbonate (CaCO3), wherein a HDPE carrier resin has a melt index of 4-10 dg / min and a density of 0.958-0.963 g / cm3; and c) CaC033 wherein CaC03 has a mean particle size of 0.7-2.5 μ, a top cut d98 of 4-15 μm, a surface area of 3.3-10.0 mVg, and a total concentration in the film of 5-35% by weight, wherein CaCO3 has been treated with a surface treatment agent at a treatment level of 0.3-2.3% by weight, and wherein CaCO3 and the HDPE carrier resin are present in a ratio from 15/85 to 80/20 in weight.

11. The film according to claim 10, characterized in that the CaC03 has been wet milled and / or dry milled prior to the incorporation of the CaCO3 into the film and, preferably, has been wet milled in the presence or absence of a grinding aid and, more preferably, it has been wet milled in the presence of a grinding aid comprising a polyacrylic acid salt and / or a salt of an acrylic acid copolymer and, where the calcium carbonate is optionally drying after grinding, and wherein CaC03 is optionally treated with the surface treatment agent before and / or during and / or after grinding of CaCO3 preferably at a treatment level of 1.5-3 mg of agent of surface treatment / m2 CaC03.

12. A film comprising: a) a high density polyethylene (HDPE) having a density of 0.958-0.963 g / cm3, and b) calcium carbonate (CaC03) having an average particle size of 0.7-2.5 μ? t ?, preferably of 1.4-2.0 μ?, and more preferably 1.4? μ ??, a top cut d98 of 4-15 μ ?, preferably of 8-10 μ ?, and most preferably of 8 μ? t ?, a surface area of 3.3-10.0 m2 / g, of preferably 3.3-5.5 m2 / g and more preferably 5.5 m2 / g, and a total film concentration of 5-35% by weight.

The film according to any of claims 1 to 12, characterized in that the CaCO3 has been treated with a surface treatment agent at a treatment level of 0.3-2.3% by weight, preferably 0.8-1.1% by weight. weight, and more preferably 1.1% by weight, and wherein the surface treating agent is optionally one or more fatty acids having from 8 to 24 carbon atoms, and preferably is one or more of arachidic acid, Behenic acid, capric acid, cerotic acid, isostearic acid, lauric acid, myristic acid, montanic acid, palmitic acid and stearic acid, most preferably comprises stearic acid.

A multi-layer film comprising the film according to any one of claims 1 to 7 and 10 to 13.

15. A method for making a masterbatch composition of calcium carbonate (CaC03) and a high-density polyethylene (HDPE). density to prepare a film, the method comprising mixing the CaC03 with a polyolefin-bearing resin, preferably a high density polyethylene (HDPE), wherein the CaCO3 and the carrier resin are present in a ratio of 15/85 to < 60/40 in weight.

16. A method for making a masterbatch composition of calcium carbonate (CaC03) and high density polyethylene (HDPE) to prepare a film, the method comprising mixing CaC03 with a HDPE carrier resin, wherein the CaC03 and the resin carrier are present in a ratio of 15/85 to 80/20 by weight.

17. The method according to any of claims 15 to 16, characterized in that the carrier resin has a melt index of 4-10 dg / min.

18. The method with any of claims 15 to 17, characterized in that the CaCO3 has an average particle size of 0.7-2.5 μGt ?, preferably of 1.4-2.0 pm and more preferably of 1.4 μ? .

19. The method with any of claims 15 to 18, characterized in that the CaCO3 has an upper cutoff d98 of 4-15 μ? T ?, preferably of 8-10 pm and most preferably of 8 pm.

20. The method according to any of claims 15 to 19, characterized in that the CaCO3 has a surface area of 3.3-10.0 m2 / g, preferably 3.3-5.5 m2 / g and more preferably 5.5 m2 / g.

21. The method with any of claims 15 to 20, characterized in that the CaCO3 has been treated with an agent of surface treatment at a treatment level of 0.3-2.3% by weight, preferably 0.8-1.1% by weight and more preferably 1.1% by weight, and wherein the surface treatment agent is optionally one or more fatty acids having from 8 to 24 carbon atoms, preferably one or more of arachidic acid, behenic acid, capric acid, ceric acid, isostearic acid, lauric acid, myristic acid, montanic acid, palmitic acid and stearic acid, more preferable comprises stearic acid.

22. A masterbatch composition of calcium carbonate comprising 50% by weight calcium carbonate of 1.4 μ? medium diameter particle size, upper cut particle size d98 of 8.0 μm, with 1.1 wt% surface treatment of stearic acid, in a high density polyethylene (HDPE) carrier resin of 50 wt% of 0.962g / cm3 of density and 6.5 dg / min of melting index.

23. A method for making a film comprising polyolefin and calcium carbonate (CaCO3), wherein the method comprises combining (a) the master mix composition according to claim 22 or the master mix composition prepared in accordance with The method of any of claims 15 to 21 and (b) a polyolefin base resin.

24. The method according to claim 23, characterized in that the CaCO3 is present in the film in a total concentration of 5% -35% by weight.

25. A master mix composition prepared by the method according to any of claims 15 to 21, or a film made by the method according to any of claims 23 to 24.

26. The film according to any of the claims 1 to 14, or the method according to any of claims 15 to 21 and 23 to 24, characterized in that the carrier resin is a medium density high molecular weight polyethylene (MMW-HDPE).

27. The film according to any of claims 1 to 14 and 25 to 26, or the method according to any of claims 15 to 21 and 23 to 24, characterized in that the concentration of calcium carbonate (CaC03) in the film is 20% -30%, and preferably is 25%.

28. The film according to any of claims 1 to 14 and 25 to 27, or the method according to any of claims 15 to 21 and 23 to 24, characterized in that the carrier resin has a melt index of 6.5- 8.0 dg / min, and preferably 6.5 dg / min.

29. The film according to any of claims 1 to 14 and 25 to 27, or the method according to any of claims 15 to 21 and 23 to 24, characterized in that the CaC03 and the carrier resin are present in a ratio 40/60 to 80/20 in weight, preferably 40/60 to < 60/40 in weight, more preferably 45/55 to 55/45 in weight and more preferably 50/50 by weight.

The film according to any one of claims 1 to 14, characterized in that the wet vapor transmission rate (MVTR) is reduced compared to the film in the absence of CaC03.

The film according to claim 30, characterized in that the wet vapor transmission rate (MVTR) is reduced by 10-30%, preferably by 20-30% by weight and more preferably by 25-30%, compared to the MVTR of the film in the absence of CaCo3.

32. The film according to claim 1 to 14 and 25 to 31, characterized in that the wet vapor transmission rate (MVTR) is 0.213-0.230 g water vapor-thousandth of an inch / 100 inch2 of film / day at 37.5 ° C and 100% relative humidity, and preferably 0.213 g water vapor-thousandth of an inch / 100 inch2 film / day at 37.5 ° C and 100% relative humidity.

33. A packaging film comprising the film according to any of claims 1-14 and 25 to 32 characterized in that the packaging film is preferably for moisture sensitive materials such as food packaging film, a packaging film of animal feed or a pharmaceutical packaging film and, most preferably, is for dry food products such as cereal or biscuits.