USE OF AGENTS TO REDUCE CRYSTALLINITY IN POLYPROPYLENE FOR BOPP APPLICATIONS.

Abstract

The BOPP film includes a polypropylene, an absence of a nucleating agent, and an additive mixed with the polypropylene forming the polypropylene / additive mixture, wherein the additive is potassium stearate.

Description

USE OF AGENTS TO REDUCE CRYSTALLINITY IN POLYPROPYLENE FOR BOPP APPLICATIONS BACKGROUND Technical Field This description relates to biaxially oriented polypropylene (BOPP) films and their manufacture. Background Biaxially oriented polypropylene (BOPP) film is used in a wide variety of flexible packaging applications. In the BOPP process, polypropylene is melted to form a sheet that is partially or completely crystallized. The sheet is then biaxially oriented to form a thin film. As used herein, the term biaxially oriented refers to a process in which a polymer composition is heated to a temperature at or above its glass transition temperature. Immediately after heating, the material can then be extruded into a film and stretched in both a longitudinal (i.e., machine direction) and a transverse or lateral (i.e., tension direction) direction. Such stretching can be carried out simultaneously or sequentially. BRIEF DESCRIPTION OF THE INVENTION One embodiment of the present description includes a BOPP film. The BOPP film comprises polypropylene, the absence of a nucleating agent, and an additive mixed with the polypropylene forming a polypropylene / additive mixture, wherein the additive is potassium stearate. In another embodiment of the present description, a process for manufacturing a BOPP film is described. The process includes mixing polypropylene with an additive to form a polypropylene / additive mixture without adding a nucleating agent, wherein the additive is potassium stearate, which melts the polypropylene / additive mixture to form a sheet, and biaxially orienting the sheet to form a thin film. In another embodiment of the present description, a method for reducing the crystallization rate during the processing of BOPP films is described. The method includes mixing polypropylene with an additive to form a polypropylene / additive mixture without adding a nucleating agent and forming a thin film of the propylene / additive mixture, wherein the additive is potassium stearate. BRIEF DESCRIPTION OF THE DRAWINGS For a more complete understanding of the present description and its advantages, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, where similar reference numbers represent similar parts. FIG. 1 is a graph that represents the yield strength value in the machine direction as a function of the heating temperature as measured by the Bruckner Karo IV Laboratory Stretcher for polypropylene grades 3270, 3273 and 3371. FIG. 2 is a graph that represents the time for half recrystallization time at 122°C versus heat flow for polypropylene grades 3270, 3273, and 3371. FIG. 3 is a graph that represents the percentage of crystallized material for polypropylene grades 3270, 3270 with an additive, 3273, and 3371, as a function of time. DETAILED DESCRIPTION A detailed description will now be provided. The description includes specific modalities, versions, and examples, but it is not limited to these modalities, versions, or examples, which are included to enable a person of ordinary skill in the technique to create and use the description when that information is combined with available information and technology. Several terms as used herein are shown below. To the extent that a term used in a claim is not defined below, it shall be given the broadest definition given to that term by persons skilled in the relevant art, as reflected in printed publications and patents issued at the time of filing. Furthermore, unless otherwise specified, all compounds described herein may be substituted or unsubstituted, and the list of compounds includes derivatives thereof. This document describes polymer compositions and articles made from them. In some embodiments, the polymer compositions include polyolefins, including, but not limited to, polypropylene. Non-limiting examples of suitable polyolefins for this description include polypropylene homopolymers and copolymers. In one embodiment, the polyolefin is polypropylene. Polypropylene can be a homopolymer. Polypropylene homopolymers suitable for use in this description can include any type of polypropylene. For example, the polypropylene homopolymer can be atactic polypropylene, isotactic polypropylene, hemi-isotactic polypropylene, syndiotactic polypropylene, or combinations thereof. A polymer is atactic when its pendant groups are arranged randomly on both sides of the polymer chain. In contrast, a polymer is isotactic when all of its pendant groups are arranged on the same side of the chain and syndiotactic when its pendant groups alternate on opposite sides of the chain. In a hemi-isotactic polymer, every other repeating unit has a random substituent. In one embodiment, a polypropylene homopolymer suitable for use in this description may have a density of 0.895 g / cc to 0.920 g / cc, alternatively from 0.900 g / cc to 0.915 g / cc, and alternatively from 0.905 g / cc to 0.915 g / cc as determined in accordance with ASTM D1505; a melting temperature of 150°C to 170°C, alternatively from 155°C to 168°C, and alternatively from 160°C to 165°C as determined by differential scanning calorimetry; and a melt flow rate of 0.5 g / 10 min. to 50 g / 10 min. alternatively from 1.0 g / 10 min. to 10 g / 10 min., and alternatively from 1.5 g / 10 min. to 5.0 g / 10 min. as > is determined in accordance with condition L of ASTM DI238; a tensile modulus of 200,000 psi to 350,000 psi; alternatively from 220,000 psi to 320,000 psi, and alternatively from 250,000 psi to 320,000 psi as determined in accordance with ASTM D638; a yield tensile strength of 3,000 psi to 6,000 psi, alternatively from 3,500 psi to 5,500 psi, and alternatively from 4,000 psi to 5,500 psi as determined in accordance with ASTM D638; a yield tensile strain of 5% to 30%, alternatively from 5% to 20%, and alternatively from 5% to 15% as determined in accordance with ASTM D638; a flexural modulus of 120,000 psi to 330,000 psi, alternatively from 190,000 psi to 310,000 psi, and alternatively from 220,000 psi to 300,000 psi as determined in accordance with ASTM D7 90; a Gardner impact of 3 in-lb to 50 in-lb, alternatively from 5 in-lb to 30 in-lb, and alternatively from 9 in-lb to 25 in-lb as determined in accordance with ASTM D2463; a Notched Izod Impact Force of 0.2 ft lb / in to 20 ft lb / in, alternatively from 0.5 ft lb / in to 15 ft lb / in, and alternatively from 0.5 ft lb / in to 10 ft lb / in as determined in accordance with ASTM D256A; a shore hardness D of 30 to 90, alternatively 50 to 85, and alternatively 60 to 80 as determined in accordance with ASTM D2240; and a heat distortion temperature of 50°C to 125°C, alternatively 80°C to 115°C, and alternatively 90°C to 110°C as determined in accordance with ASTM D648. Non-limiting examples of polypropylene homopolymers suitable for use in this description include, without limitation, 3371, 3273, and 3270, which are commercially available polypropylene homopolymers from Total Petrochemicals & Refining USA, Tnc. In one embodiment, the polypropylene homopolymer (e.g., 3371) generally has the physical properties set forth in Table 1. Table 1 Properties Typical Value 3371 Test Method Physical Density, g / cc 0.905 ASTM D1505 Melting Flow Rate (MFR), g / 10 min. 2.8 ASTM D123 8 Melting Point (DSC), °F (°C) 325 (163) DSC Oriented Film Properties Haze 1% ASTM D123 Gloss 45° 90% ASTM D2457 Elongation 130% MD, 50% TD ASTM D882 Ultimate Tensile Strength 19,000 psi MD, 38,000 psi TD ASTM D882 Tensile Modulus 350,000 psi MD, 600,000 psi TD ASTM D882 WVTR 0.3 g / 100 in² / 24 hrs / mil (2; 100°F, 90% TA ASTM F-1249-90 In another embodiment, polypropylene may be a high-crystallinity polypropylene homopolymer (HCPP). HCPP may primarily contain isotactic polypropylene. Polymer isotacticity can be measured by 13C NMR spectrometry using mesopentavalents and can be expressed as a percentage of mesopentavalents (%mmmm). As used herein, the term mesopentavalents refers to successive methyl groups located on the same side of the polymer chain. In one embodiment, HCPP has a mesopentavalent percentage greater than 95%, or greater than 98%, or greater than 99%. HCPP may comprise equal amounts of atactic or amorphous polymer. The atactic portion of the polymer is soluble in xylene and is thus referred to as the xylene-soluble fraction (XS%).In the XS% ​​determination, the polymer is dissolved in boiling xylene, and the solution is then cooled to 0°C, resulting in the precipitation of the isotactic or crystalline portion of the polymer. XS% is that portion of the original amount that remained soluble in the cooled xylene. Consequently, the XS% ​​in the polymer is indicative of the degree of crystalline polymer formed. The total amount of polymer (100%) is the sum of the xylene-soluble fraction and the xylene-insoluble fraction, as determined according to ASTM D5492-98. In one embodiment, HCPP has a xylene-soluble fraction of less than 1.5%, less than 1.0%, or less than 0.5%. In one embodiment, an HCPP suitable for use in this description may have a density of 0.895 g / cc to 0.920 g / cc, alternatively from 0.900 g / cc to 0.915 g / cc, and alternatively from 0.905 g / cc to 0.915 g / cc as determined in accordance with ASTM D1505; a melt flow rate of 0.5 g / 10 min. to 500 g / 10 min., alternatively from 1.0 g / 10 min. to 100 g / 10 min., and alternatively from 1.5 g / 10 min. to 20 g / 10 min.as determined in accordance with ASTM D1238; a secant modulus in the machine direction (MD) of 350,000 psi to 420,000 psi; alternatively from 380,000 psi to 420,000 psi, and alternatively from 400,000 psi to 420,000 psi as determined in accordance with ASTM D882; a secant modulus in the transverse direction (TD) of 400,000 psi to 700,000 psi, alternatively from 500,000 psi to 700,000 psi, and alternatively from 600,000 psi to 700,000 psi as determined in accordance with ASTM D882; a tensile strength at break in the MD of 19,000 psi to 28,000 psi, alternatively from 22,000 psi to 28,000 psi, and alternatively from 25,000 psi to 28,000 psi as determined 5 in accordance with ASTM D882; a tensile strength at break in the TD of 20,000 psi to 40,000 psi, alternatively from 30,000 psi to 40,000 psi, and alternatively from 35,000 psi to. 40,000 psi as determined in accordance with ASTM D882; an elongation at break at MD of 50% to 200%, alternatively from 100% to 180%, and alternatively from 120% to 150% as determined in accordance with ASTM D882; an elongation at break at TD of 50% to 150%, alternatively from 60% to 100%, and alternatively from 80% to 100% as determined in accordance with ASTM D882; a melting temperature of 150°C to 170°C, alternatively from 155°C to 170°C, and alternatively from 160°C to 170°C as determined by differential scanning calorimetry; a brightness at 45° of 70 to 95, alternatively from 75 to 90, and alternatively from 80 to 90 as determined in accordance with ASTM D2457; a nebulosity of 0.5% to 2.0%, alternatively from 0.5% to 1.5%, and alternatively from 0.5% to 1.0% as determined in accordance with ASTM D1003; and a water vapor transmission rate of 0.15 to 0.30 g-mil / 100in2 / day, alternatively from 0.15 to 0.25 g-mil / 100in2 / day, and alternatively from 0.20 to 0.21 g-25 mil / 100in2 / day as determined in accordance with ASTM F-1249-90. An example of an HCPP suitable for use in this description includes, without limitation, 3270, which is a commercially available HCPP from Total Petrochemicals & Refining USA, Inc. The HCPP (e.g., 3270) can generally have 5 of the physical properties set out in Table 2. Table 2 Properties Typical Value 3270 Test Method Physical Density, g / cc 0.91 ASTM D1505 Melting Flow Rate (MFR), g / 10 min. 2.0 ASTM D1238 Melting Point (DSC), °F (°C) 329 (165) DSC Oriented Film Properties Haze 1% ASTM D1003 Gloss 45° 85% ASTM D2457 Elongation 150% MD, 60% TD ASTM D882 Ultimate Tensile Strength 28,000 psi MD, 39,000 psi TD ASTM D882 Tensile Modulus 420,000 psi MD, 700,000 psi TD ASTM D882 WVTR 0.2 g / 100 in2 / 24 hrs / mil @ 100°F, 90% TA ASTM F-1249-90 Another example of an HCPP is 3273, which is a commercially available HCPP from Total Petrochemicals & Refining. USA, Lie. 3273 may generally have the physical properties 10 set out in Table 3. Table 3 Properties Typical Value 3270 Test Method Physical Density, g / cc 0.905 ASTM D1505 Melting Flow Rate (MFR), g / 10 min. 2.0 ASTM D123 8 Melting Point (DSC), °F (°C) 325 (163) DSC <2) Oriented Film Properties Haze 1% ASTM D1003 Gloss 45° 85% ASTM D2457 Elongation 150% MD, 60% TD ASTM D882 Ultimate Tensile Strength 24,000 psi MD, 38,000 psi TD ASTM D8 82 Tensile Modulus 400,000 psi MD, 686,000 psi TD ASTM D882 WVTR 0.25 g / 100 in2 / 24 hrs / mil (®r 100°F, 90% TA ASTM F-1249-90 In another embodiment, polypropylene can be a polypropylene copolymer. In certain embodiments, the polypropylene copolymer can be a random copolymer of propylene. Examples of polypropylene copolymers include 5 random copolymers of propylene made from catalysts of Zieger-Natta, such as the commercially available 6000, 7000, and 8000 series from Total Petrochemicals & Refining USA, Inc. In other embodiments, propylene-based polymers can be mini-random polypropylene. A mini-random polypropylene has less than approximately 1.0% by weight of the comonomer. In certain embodiments, the comonomer in the mini-random polypropylene is ethylene. In another form, polypropylene is a high-melt-strength polypropylene. A high-melt-strength polypropylene can be a semicrystalline polypropylene or a polypropylene copolymer matrix containing a heterophasic copolymer. The heterophasic copolymer may include ethylene and a higher alpha-olefin polymer, such as an amorphous ethylene-propylene copolymer, for example. The polyolefins suitable for use in this description can be prepared using any suitable method. For example, polyolefin can be prepared using a Ziegler-Natta catalyst, a metallocene catalyst, or combinations thereof. Polyethylene, for example, can be prepared using a chromium oxide catalyst or any other suitable catalyst. In one embodiment, the polyolefin is prepared using Ziegler-Natta catalysts, which are typically based on titanium and organometallic aluminum compounds, for example triethylaluminum (C2H5)3A1. Ziegler-Natta catalysts and processes for forming such catalysts are described in U.S. Patent Nos. 4,298,718; 4,544,717; and 4,767,735, each of which is incorporated herein by reference in its entirety. In another modality, the polyolefin can be prepared using a metallocene catalyst. Metallocene catalysts can generally be characterized as compounds coordination groups that incorporate one or more cyclopentadienyl (Cp) groups (which may be substituted or unsubstituted, each substitution being the same or different) coordinated with a transition metal through the π bond. Examples of metallocene catalysts and processes for forming such catalysts are described in U.S. Patents Nos. 4,794,096 and 4,975,403, each of which is incorporated herein by reference in its entirety. Examples of polyolefins prepared through the use of metallocene catalysts are described in further detail in U.S. Patents Nos. 5,158,920; 5,416,228; 5,789,502; 5,807,800; 5,968,864; 6,225,251; 6,777,366; 6,777,367; 6,579,962; 6,468,936; 6,579,962; and 6,432,860, each of which is incorporated herein by reference in its entirety. The polyolefin can also be prepared using any other catalyst or catalyst system such as a combination of Ziegler-Natta and metallocene catalysts, for example as described in U.S. Patents Nos. 7,056,991 and 6,653,254, each of which is incorporated herein by reference in its entirety. Polyolefin can be formed by placing one or more olefin monomers, alone or with other monomers, in a suitable reaction vessel in the presence of a catalyst (e.g., Ziegler-Natta, metallocene, etc.) and under reaction conditions suitable for its polymerization. Any suitable equipment and processes can be used to polymerize the olefin into a polymer. For example, such processes may include solution-phase, gas-phase, suspension-phase, bulk-phase, high-pressure processes, and combinations thereof. Such processes are described in detail in U.S. Patents Nos. 5,525,678; 6,420,580; 6,380,328; 6,359,072; 6,346,586; 6,340,730; 6,339,134; 6,300,436; and 6,274,684. 6,271,323; 6,248,845; 6,245,868; 6,245,705; 6,242,545; 6,211,105; 6,207,606; 6,180,735; and 6,147,173, which are incorporated herein by reference in their entirety. In one embodiment, the polyolefin is formed by a gas-phase polymerization process. An example of a gas-phase polymerization process includes a continuous-cycle system, where the cycling gas stream (otherwise known as a recycle stream or fluidization medium) is heated in a reactor by the heat of polymerization. Heat is removed from the cycling gas stream elsewhere in the cycle by a cooling system external to the reactor. The cycling gas stream containing one or more monomers can be continuously recycled through a fluidized bed in the presence of a catalyst under reactive conditions. The cycling gas stream is typically withdrawn from the fluidized bed and recycled back into the reactor. Simultaneously, the polymer product can be withdrawn from the reactor, and fresh monomer can be added to replace the polymerized monomer.The reactor pressure in a gas-phase process can vary from 100 psig to 500 psig, or from 200 psig to 400 psig, or from 250 psig to 350 psig. The reactant temperature in a gas-phase process can vary from 30°C to 120°C, or from 60°C to 115°C, or from 70°C to 110°C, or from 70°C to 95°C, for example as described in U.S. Patents Nos. 4,543,399; 4,588,790; 5,028,670; 5,317,036; 5,352,749; 5,405,922; 5,436,304; 5,456,471;. 5,462,999; 5,616,661; 5,627,242; 5,665,818; 5,677,375; and 5,668,228, which are incorporated herein by reference in their entirety. In one embodiment, the polyolefin is formed by a suspension-phase polymerization process. The processes Suspension-phase polymerization generally involves forming a suspension of particulate, solid polymer in a liquid polymerization medium, to which monomers and optionally hydrogen, along with the catalyst, are added. The suspension (which may include diluents) can be removed intermittently or continuously from the reactor where volatile components can be separated from the polymer and recycled, optionally after distillation, back to the reactor. The liquefied diluent used in the polymerization medium may include a C3 to C7 alkane (e.g., hexane or isobutene). The medium used is generally liquid under the polymerization conditions and relatively inert. A bulk-phase process is similar to a suspension process. However, a process can be a bulk-phase process, a suspension process, or a bulk-suspension process. BOPP film can be formed as described above. During the orientation process, the pre-existing crystal regions in the polypropylene sheet can be disrupted and reformed to produce a high level of crystallinity with strong additional components in both orientation directions, i.e., MD and TD. This high level of crystallinity results in high stiffness, high barrier properties, and high tensile strength in the BOPP film. In certain formulations, the orientation process is a solid-state orientation process, which can result in the destruction of crystal regions formed during the initial casting stage, such as through heat and force. The rate at which polypropylene is processed to produce BOPP film can be limited by the ability to heat the material sufficiently to reduce the crystalline content, by the amount of force (as a function of the rate at which force is applied) that can be applied to the sheet, or by both. For example, when excessive force is applied at too high a rate, the film may tear or fail to orient uniformly. Heat can be applied to the film via induction before each orientation stage. Heat transfer limitations will restrict the rate at which a material can be processed. Furthermore, increasing the temperatures used to heat the film during processing can result in film adhesion to the surfaces in contact during processing. The level of crystallinity in the sheet can influence the amount of force and heat required to remove the thin film during processing. A film with higher crystallinity may require higher temperatures during heating, longer exposure to elevated temperatures, or more force for removal compared to sheets with lower crystallinity. By controlling the reaction during polypropylene manufacturing, it is possible to control the level of crystallinity in the manufactured polypropylene. The level of crystallinity can be measured by the amount of polypropylene extracted in hot xylene as a weight percent (%XS), with more polypropylene being extracted in materials with lower crystallinity. Table 5 shows %XS for 3270, 3273, and 3371. While 3270, 3273, and 3371 are all homopolymer polypropylenes, each of them differs in molecular architecture, resulting in the differences in %XS. Table 4 shows the level of crystallinity as measured by the percentage of extractable content in hot xylene (XS) and by C13 NMR (expressed as a mol% of 5 meso repeat units) for 3270, 3273, and 3371. The data demonstrate that the three materials differ distinctly in crystallinity, with the crystallinity of 3270 being higher than that of 3273, which in turn is higher than that of 3371. Table 4 Value 3270 3273 3371 Xylene Soluble Units (XS) 0.9 1.9 4.2 % %meso (NMR) 99 96 93 mol% (NMR) 98 94 89 Q. O In some applications, 3270 is more difficult to process than 3273; 3273 may be more difficult to process than 3371. Higher crystallinity polypropylene may require more heat and consequently decrease processing speeds than lower crystallinity material. This effect is further illustrated in Figure 1, which shows the force required to orient 3270, 3273, and 3371 as measured on a Bruckner Karo TV Laboratory Expander at various draw temperatures. Figure 1 shows the yield stress value in the machine direction (MD) as a function of heating temperature as measured by the Bruckner Karo IV Laboratory Expander for 3270, 3273, and 3371. The figure demonstrates that more force is required to orient the sheet in higher crystallinity materials at any given heating temperature.While crystallinity can be altered during the formation of polypropylene resin, reducing the crystallinity of the polypropylene resin can adversely impact the properties of the final film. For example, polypropylene resins with lower crystallinity can lead to films with reduced stiffness and barrier properties. The level of crystallinity can also be controlled by the way the sheet is formed. Lower sheet formation temperatures can be used to decrease sheet crystallinity by providing lower orientation forces and / or reheating temperatures. While not theoretically related, a high level of supercooling can lead to less crystal perfection and a lower level of crystallinity. In some embodiments of the present description, an additive can be used to suppress or slow crystallization, i.e., reduce the crystallization rate, in a polypropylene material to reduce the force and / or temperature used to orient the material while still resulting in a film with the same properties. The additive can allow higher processing speeds in polypropylene in which the additive is introduced without compromising the final film properties, as shown in Table 5 for films oriented on the Bruckner Karo IV Laboratory Stretcher at a 5:5 stretch ratio at 150°C. In certain embodiments, the concentration of the additive in the polypropylene can be between 100 ppm and 2000 ppm, between 400 ppm and 600 ppm, or approximately 500 ppm. Table 5 Value 3270 3270 + Additive Film Thickness, mil 0.6 0.6 Drying Modulus 1% Tensile Strength MD, kpsi 328 334 Tensile Strength Breaking Strength MD, psi 31000 31100 Elongation MD, Breaking Strength, % 120 130 Drying Modulus 1% Tensile Strength TD, kpsi 350 340 Tensile Strength Breaking Strength TD, psi 34000 32900 Elongation TD, Breaking Strength, % 110 110 Transmittance, % 94.1 94.2 Haze, % 0.4 0.3 Draft, g, 220 230 An example of such an additive is potassium stearate. Figure 2 illustrates the effect of adding this additive on the crystallization of 3371, 3273, and 3270. Figure 2 plots the mean recrystallization time at 122°C against heat flow. Comparing the crystallization of 3371, 3273, and 3270, it is evident that as crystallinity increases, the onset of crystallization becomes faster (Figure 2). This is accompanied by an increase in the strength to orient at a given temperature (Figure 1). This behavior can be important in a dynamic process such as BOPP orientation. Due to the slow nature of polypropylene crystallization compared to other materials, polypropylene can only be partially crystallized during the BOPP process. If the crystallization process can be slowed down, at any given point in the BOPP process, the weight fraction of crystallinity in a molten sheet will be lower.Figure 3 shows the percentage of crystallized material for materials with different levels of inherent crystallinity as a function of time. The effect of adding an additive—potassium stearate (Al)—on the crystallization of a high-crystallinity product is to induce the material to behave more similarly to a low-crystallinity product, as also shown in Figure 3. The concentration of potassium stearate in the polypropylene was 500 ppm. Thus, the polypropylene with this additive is expected to process more similarly to a lower-crystallinity polypropylene, requiring less heat, shorter induction times, and higher processing rates. However, unexpectedly, the additive / polypropylene mixture has a lower crystallization temperature than identical polypropylene without the additive, compared to the presence of other agents such as nucleating agents.However, because the final film structure is induced through orientation in the BOPP process, the properties of the final BOPP film—namely, cloudiness, brightness at 45°, elongation, ultimate tensile strength, tensile modulus, and WVTR—are not found to be negatively impacted by the additive. In certain embodiments, no nucleating agent is added to the polypropylene or the polypropylene / additive blend. Unexpectedly, potassium stearate lowers the crystallization temperature of the polypropylene / additive blend in the absence of a nucleating agent. Furthermore, in certain embodiments, the additive is added to the polypropylene during manufacturing or at a secondary stage. In certain embodiments, BOPP films are single-layer films. In other embodiments, BOPP films may form one or more layers of a multi-layer film. The additional layers of the multi-layer film may be any coextrudable film known in the art, such as syndiotactic polypropylene, low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene copolymers, butylene-propylene copolymers, ethylene-butylene copolymers, ethylene-propylene-butylene terpolymers, ethylene-vinyl acetate copolymers, ethylene-vinyl alcohol copolymers, nylon, and similar materials or combinations thereof.

Claims

1. CLAIMS 1. A BOPP film, characterized in that it comprises: a polypropylene; an absence of a nucleating agent; and an additive mixed with the polypropylene forming a polypropylene / additive mixture, wherein the additive is potassium stearate.

2. The BOPP film according to claim 1, characterized in that the concentration of potassium stearate in the polypropylene / additive mixture is between 100 ppm and 2000 ppm.

3. The BOPP film according to claim 2, characterized in that the concentration of potassium stearate in the polypropylene / additive mixture is between 400 ppm and 600 ppm.

4. The BOPP film according to claim 1, characterized in that the polypropylene is a polypropylene homopolymer.

5. The BOPP film according to claim 4, characterized in that the polypropylene homopolymer is an HCPP having a mesopentate percentage greater than 95%.

6. The BOPP film according to claim 1, characterized in that the polypropylene is a polypropylene copolymer.

7. The BOPP film according to claim 6, characterized in that the polypropylene copolymer is a random copolymer.

8. The BOPP film according to claim 7, characterized in that the random copolymer is a mini-random copolymer.

9. The BOPP film according to claim 1, characterized in that a crystallization rate in the film during manufacturing is lower than if the additive had not been mixed with the polypropylene.

10. The BOPP film according to claim 1, characterized in that the nebulosity, brightness 45°, elongation, end stress, tensile modulus, and WVTR of the BOPP film are not negatively impacted by the addition of the additive.

11. A manufacturing process for a BOPP film, characterized in that it comprises: mixing polypropylene with an additive to form a polypropylene / additive mixture without adding a nucleating agent, wherein the additive is potassium stearate; pouring the polypropylene / additive mixture to form a sheet; and biaxially orienting the sheet to form a thin film.

12. The process according to claim 11, characterized in that the concentration of potassium stearate in the polypropylene / additive mixture is between 100 ppm and 2000 ppm.

13. The process according to claim 11, characterized in that the level of crystallinity in the sheet during processing is lower than if the additive had not been mixed with the polypropylene.

14. The process according to claim 13, characterized in that a crystallization rate in the manufacturing process of the BOPP film is lower than if the additive had not been mixed with the polypropylene.

15. The process according to claim 13 characterized in that the BOPP film manufacturing process requires less heat, has a shorter induction time, has a higher process speed or a combination thereof than if the additive had not been mixed with the polypropylene.

16. The process according to claim 11, characterized in that the crystallization rate in the thin film during processing is less than if the additive had not been mixed with the polypropylene.

17. The process according to claim 11, characterized in that the nebulosity, brightness 45°, elongation, end strain, strain modulus, and WVTR of the thin film are not negatively impacted by the addition of the additive.

18. The process according to claim 11, characterized in that at any point during the steps of pouring the polypropylene / additive mixture to form a sheet and biaxially orienting the sheet to form a thin film, the crystallinity will be less than if the additive had not been mixed with the polypropylene.

19. A method for reducing the crystallization rate during the processing of BOPP films, characterized in that it comprises: mixing polypropylene with an additive to form a polypropylene / additive mixture without adding a nucleating agent; and forming a thin film from the polypropylene / additive mixture, wherein the additive is potassium stearate.

20. The method according to claim 19, characterized in that no nucleating agent is added to the polypropylene.

21. The BOPP film according to claim 20, characterized in that the concentration of potassium stearate in the polypropylene / additive mixture is between 100 ppm and 2000 ppm.

22. The BOPP film according to claim 21, characterized in that the concentration of potassium stearate in the polypropylene / additive mixture is between 400 ppm and 600 ppm.

23. The BOPP film according to claim 19, characterized in that the polypropylene is a polypropylene homopolymer.

24. The BOPP film according to claim 23, characterized in that the polypropylene homopolymer is an HCPP having a mesopentate percentage greater than 95%.

25. The BOPP film according to claim 19, characterized in that the polypropylene is a polypropylene copolymer.

26. The BOPP film according to claim 25, characterized in that the polypropylene copolymer is a random copolymer.

27. The BOPP film according to claim 26, characterized in that the random copolymer is a mini-random copolymer.