High-surface-tension master batch for BOPP (biaxially-oriented polypropylene) film and preparation method of master batch

Abstract

The invention discloses a high-surface-tension master batch for a BOPP (biaxially-oriented polypropylene) film and a preparation method of the master batch. The master batch comprises PP resin, nanoscale organic modified montmorillonite, maleic anhydride grafted polypropylene, a composite modifier and an antioxidant, wherein the composite modifier is composed of a fluorine-containing surfactant, a silane coupling agent and an amide slipping agent according to a weight ratio of 1: (0.5-1.5): (2-3). The preparation method comprises the following four main steps: raw material pretreatment, gradient mixing, melt blending and granulation post-treatment. Through unique formula design and process control, the surface tension of the prepared BOPP film can reach 42-45 mN / m when the BOPP film is not subjected to corona treatment, and the problems that a traditional BOPP film depends on corona treatment and the effect of the traditional BOPP film is attenuated are effectively solved. The master batch has the advantages of small addition amount, obvious effect, no influence on the optical and mechanical properties of the film, stable and reliable production process, and obvious economic benefit and popularization and application value.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a high surface tension masterbatch for BOPP film and its preparation method. Background Technology

[0002] Bis-oriented polypropylene (BOPP) film is widely used in the packaging of food, pharmaceuticals, cosmetics, and other products due to its excellent transparency, mechanical strength, and barrier properties. During the packaging printing process, the surface tension of the BOPP film is a key factor affecting ink adhesion and print quality. Typically, to achieve good printing results, the surface tension of the BOPP film needs to reach 38 mN / m or higher.

[0003] Currently, corona treatment is commonly used in industry to improve the surface tension of BOPP films. Corona treatment generates polar groups on the film surface through high-voltage discharge, thereby increasing the surface energy. However, this method has significant limitations: First, the effect of corona treatment decays over time, and the surface tension of the film decreases significantly after a period of storage, affecting the quality of subsequent printing; second, corona treatment requires additional equipment and energy consumption, increasing production costs; and third, excessive corona treatment may damage the film surface, affecting its mechanical properties.

[0004] To overcome the shortcomings of corona treatment, the industry has attempted to add functional masterbatches to BOPP films to improve their surface properties. Some related research exists in the existing technology, such as adding slip masterbatches to improve the film's opening properties and adding antistatic masterbatches to prevent static electricity accumulation. However, these masterbatches mainly focus on a specific property of the film, with limited effect on improving surface tension. Some studies have attempted to increase the film's surface tension by adding surfactants, but this introduces new problems: on the one hand, small molecule surfactants are prone to migration and precipitation, leading to unstable surface tension; on the other hand, excessive addition can affect the film's transparency and mechanical properties.

[0005] In recent years, the application of nanomaterials in polymer modification has provided new insights into solving this problem. Nano-montmorillonite, due to its unique layered structure and large specific surface area, has shown potential in improving polymer surface properties. However, unmodified montmorillonite has poor compatibility with polypropylene matrices and is prone to agglomeration, which can degrade film properties. Although organic modification can improve the dispersibility of montmorillonite, how to increase surface tension without affecting other film properties remains a technical challenge.

[0006] Therefore, to address the above-mentioned problems, this invention provides a high surface tension masterbatch for BOPP film and its preparation method. Through unique formulation design and optimized preparation process, a synergistic effect is established between nano-organic modified montmorillonite and composite modifier, which significantly improves the surface tension of BOPP film while ensuring the overall performance of the film, providing an effective technical solution to the problems in the prior art. Summary of the Invention

[0007] The purpose of this invention is to provide a high surface tension masterbatch for BOPP film and its preparation method, which solves the problems of insufficient surface tension of existing BOPP films, reliance on corona treatment, and adverse effects of existing masterbatches on other film properties.

[0008] The objective of this invention is achieved through the following technical solution: A high surface tension masterbatch for BOPP film is composed of the following raw materials in parts by weight: PP resin: 70-85 parts; Nanoscale organic-modified montmorillonite: 5-12 parts; Maleic anhydride-grafted polypropylene: 8-15 parts; Composite modifier: 1.5~2.5 parts; Antioxidant: 0.1~0.3 parts; The composite modifier is composed of fluorinated surfactant, silane coupling agent and amide slip agent in a weight ratio of 1:(0.5~1.5):(2~3).

[0009] Preferably, the nanoscale organic-modified montmorillonite has an interlayer spacing of 2.0~3.5 nm and a specific surface area of ​​500~800 m². 2 / g, and its surface modification adopts a dual modification process: first, it is treated with quaternary ammonium salt intercalation, and then it is modified with silane coupling agent.

[0010] Preferably, the maleic anhydride-grafted polypropylene has a grafting rate of 1.2-2.0%, a melt flow rate (MFR) of 5-10 g / 10 min (test conditions are 230℃ and 2.16 kg load), and acts as both a compatibilizer and a surface tension enhancer in the masterbatch.

[0011] Preferably, the fluorinated surfactant in the composite modifier is a perfluoroalkyl ether, the silane coupling agent is an aminosilane, and the amide slip agent is a complex of erucamide and oleamide, wherein the weight ratio of erucamide to oleamide is 1:(0.8~1.2).

[0012] Preferably, the PP resin is a highly crystalline homopolymer polypropylene with an isotacticity greater than 98%, a melt flow rate of 3~6 g / 10 min (test conditions are 230℃ and 2.16 kg load), and a molecular weight distribution index (MWD) of 4~6.

[0013] This application also claims a method for preparing the above-mentioned high surface tension masterbatch for BOPP film, comprising the following steps: (1) Pretreatment: The nano-sized organic modified montmorillonite was vacuum dried at 100~120℃ for 6~8 hours, and the moisture content was controlled to be less than 0.1%; (2) Premixing: PP resin, dried nano-sized organic modified montmorillonite, maleic anhydride grafted polypropylene, composite modifier and antioxidant are added to a high-speed mixer in proportion and a gradient mixing process is adopted: first mix at a low speed of 200~300r / min for 3~5 minutes, and then mix at a high speed of 500~800r / min for 8~12 minutes. (3) Melt blending: The premixed material is added to a co-rotating twin-screw extruder and multi-stage temperature control is adopted: Zone 1 180~190℃, Zone 2 200~210℃, Zone 3 210~220℃, Zone 4 220~230℃, and the die head 225~235℃; (4) Granulation and post-processing: The extruded strip is cooled with water and then cut into pellets. The resulting masterbatch pellets are vacuum dried at 50~70℃ for 4~6 hours.

[0014] Preferably, in step (3), the screw configuration of the twin-screw extruder adopts a special combination of mixing elements, including a kneading block, a toothed mixing element and a reverse thread element, and the screw speed is controlled at 350~450 r / min, the die head pressure is maintained at 15~25 MPa, and the vacuum degree is maintained at ~0.06 to ~0.08 MPa.

[0015] Preferably, the gradient mixing process used in step (2) specifically includes: First stage: Mix at 250 r / min for 4 minutes to initially mix the raw materials; Second stage: Mix at 600 r / min for 10 minutes to ensure that all components are thoroughly mixed and homogeneous; Third stage: Mix for 2 minutes at 150 r / min to eliminate static electricity and remove air.

[0016] Preferably, in step (3), the residence time of the material during the melt blending process is 45-60 seconds, the melt pressure is 18-22 MPa, and the melt temperature fluctuation during the extrusion process is controlled within ±2℃.

[0017] This application also claims a high surface tension BOPP film comprising the aforementioned high surface tension masterbatch for BOPP film, wherein the high surface tension masterbatch for BOPP film is added to the BOPP film in an amount of 4 to 10 parts by weight, and the BOPP film has a surface tension of 42 to 45 mN / m when not subjected to corona treatment.

[0018] Due to the application of the above technical solution, the present invention has the following beneficial effects compared with the prior art: 1. This invention, through the intrinsic modification of the masterbatch, enables BOPP film to achieve a high surface tension of 42~45mN / m without corona treatment. This characteristic completely changes the reliance of traditional production processes on corona treatment and effectively solves the technical problem of the decay of corona treatment effect over time. BOPP film products produced using the masterbatch of this invention can still maintain excellent ink adhesion during long-term storage, significantly improving the quality stability and consistency of printed materials, while greatly reducing the printing scrap rate caused by insufficient surface tension. 2. This invention achieves a synergistic effect of multiple functions. Through precise formulation design, it realizes the synergistic effect between various components. Nanoscale organic modified montmorillonite, as a reinforcing skeleton, effectively increases the microscopic polarity of the polymer surface. Maleic anhydride-grafted polypropylene, as a compatibilizer, not only improves the compatibility between montmorillonite and PP resin, but its own polar groups also directly contribute to the improvement of surface tension. The components in the composite modifier can effectively migrate to the film surface during processing to form a stable high surface energy layer. This multi-level mechanism of action ensures that the product maintains excellent surface properties without affecting other important performance indicators of the film. 3. The gradient mixing process used in this invention ensures the uniform dispersion of trace components such as nanomaterials in the carrier resin, laying a good foundation for the subsequent melt blending process; the combination of multi-stage temperature control and specific screw configuration creates an ideal plasticizing environment during twin-screw extrusion, which not only ensures the full melting and dispersion of each component, but also effectively prevents the thermal degradation of the resin; by precisely controlling key process parameters such as temperature, pressure, and vacuum, the stability of product quality and batch-to-batch consistency are ensured. 4. By reducing or eliminating the corona treatment process, this invention directly reduces the investment and operating costs of related equipment, including equipment depreciation, energy consumption, and maintenance costs. At the same time, the stable high surface tension characteristics reduce the setup time and material waste in the printing process, improving overall production efficiency. In addition, the film products have a longer shelf life, providing downstream customers with greater usage flexibility and further enhancing the product's market competitiveness. 5. The technical solution of this invention conforms to the development concept of green manufacturing; by reducing reliance on corona treatment, energy consumption in the production process is indirectly reduced; the materials used in the masterbatch formula all meet environmental protection requirements, the production process is clean and controllable, and no harmful by-products are generated; this environmentally friendly characteristic enables the product of this invention to meet increasingly stringent environmental regulations and conforms to the industry trend of sustainable development. Detailed Implementation

[0019] To provide a clearer understanding of the technical features, objectives, and effects of this invention, specific implementation schemes are now described in detail.

[0020] The present invention will be further described below with reference to embodiments, but the present invention is not limited to the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to different requirements of specific use, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in the various embodiments of the present invention can be combined with each other as long as they do not conflict with each other.

[0021] Example 1 This embodiment provides a high surface tension masterbatch for BOPP film, composed of the following raw materials in parts by weight: PP resin: 75 parts; nano-sized organic modified montmorillonite: 8 parts; maleic anhydride grafted polypropylene: 12 parts; composite modifier: 2.0 parts (including 0.5 parts of fluorinated surfactant, 0.5 parts of aminosilane, and 1.0 part of erucamide and oleamide complex, in a weight ratio of 1:1:2); antioxidant: 0.2 parts; The method for preparing the high surface tension masterbatch for BOPP film includes the following steps: (1) Pretreatment: The nano-sized organic modified montmorillonite was vacuum dried at 110℃ for 7 hours, and the moisture content was controlled to be 0.08%; (2) Premixing: PP resin, dried nano-sized organic modified montmorillonite, maleic anhydride grafted polypropylene, composite modifier and antioxidant are added to a high-speed mixer and a gradient mixing process is adopted: first mix at a low speed of 250r / min for 4 minutes, and then mix at a high speed of 600r / min for 10 minutes. (3) Melt blending: The premixed material is added to a co-rotating twin-screw extruder and multi-stage temperature control is adopted: Zone 1 185℃, Zone 2 205℃, Zone 3 215℃, Zone 4 225℃, and Die head 230℃; the screw speed is controlled at 400r / min, the die head pressure is maintained at 20MPa, and the vacuum degree is maintained at -0.07MPa; (4) Granulation and post-processing: The extruded strips are cooled with water and then granulated. The resulting masterbatch granules are vacuum dried at 60°C for 5 hours.

[0022] Example 2 This embodiment provides a high surface tension masterbatch for BOPP film, composed of the following raw materials in parts by weight: PP resin: 80 parts; nano-sized organic modified montmorillonite: 6 parts; maleic anhydride grafted polypropylene: 10 parts; composite modifier: 1.8 parts (including 0.4 parts of fluorinated surfactant, 0.4 parts of aminosilane, and 1.0 part of erucamide and oleamide complex, in a weight ratio of 1:1:2.5); antioxidant: 0.15 parts; The method for preparing the high surface tension masterbatch for BOPP film includes the following steps: (1) Pretreatment: The nano-sized organic modified montmorillonite was vacuum dried at 105℃ for 7.5 hours, and the moisture content was controlled to be 0.07%; (2) Premixing: PP resin, dried nano-sized organic modified montmorillonite, maleic anhydride grafted polypropylene, composite modifier and antioxidant are added to a high-speed mixer and a gradient mixing process is adopted: first mix at a low speed of 220r / min for 4.5 minutes, and then mix at a high speed of 550r / min for 11 minutes. (3) Melt blending: The premixed material is added to a co-rotating twin-screw extruder and multi-stage temperature control is adopted: Zone 1 182℃, Zone 2 208℃, Zone 3 218℃, Zone 4 228℃, and Die head 232℃; the screw speed is controlled at 380r / min, the die head pressure is maintained at 18MPa, and the vacuum degree is maintained at -0.065MPa; (4) Granulation and post-processing: The extruded strips are cooled with water and then granulated. The resulting masterbatch granules are vacuum dried at 55°C for 5.5 hours.

[0023] Example 3 This embodiment provides a high surface tension masterbatch for BOPP film, composed of the following raw materials in parts by weight: PP resin: 70 parts; nano-sized organic modified montmorillonite: 10 parts; maleic anhydride grafted polypropylene: 15 parts; composite modifier: 2.3 parts (including 0.6 parts of fluorinated surfactant, 0.5 parts of aminosilane, and 1.2 parts of erucamide and oleamide complex, in a weight ratio of 1:0.83:2); antioxidant: 0.25 parts; The method for preparing the high surface tension masterbatch for BOPP film includes the following steps: (1) Pretreatment: The nano-sized organic modified montmorillonite was vacuum dried at 115℃ for 6.5 hours, and the moisture content was controlled to be 0.09%; (2) Premixing: PP resin, dried nano-sized organic modified montmorillonite, maleic anhydride grafted polypropylene, composite modifier and antioxidant are added to a high-speed mixer and a gradient mixing process is adopted: first mix at a low speed of 280r / min for 3.5 minutes, and then mix at a high speed of 700r / min for 9 minutes. (3) Melt blending: The premixed material is added to a co-rotating twin-screw extruder and multi-stage temperature control is adopted: Zone 1 188℃, Zone 2 202℃, Zone 3 212℃, Zone 4 222℃, and Die head 228℃; the screw speed is controlled at 420r / min, the die head pressure is maintained at 22MPa, and the vacuum degree is maintained at -0.075MPa; (4) Granulation and post-processing: The extruded strips are cooled with water and then granulated. The resulting masterbatch granules are vacuum dried at 65°C for 4.5 hours.

[0024] Comparative Example 1 This comparative example is based on Example 1 above. The similarities with Example 1 above will not be repeated. This comparative example does not add nano-sized organic modified montmorillonite; PP resin: 83 parts; maleic anhydride grafted polypropylene: 12 parts; composite modifier: 2.0 parts; antioxidant: 0.2 parts; the preparation method is the same as in Example 1.

[0025] Comparative Example 2 This comparative example is based on Example 1 above. The similarities with Example 1 above will not be repeated. In this comparative example, maleic anhydride-grafted polypropylene is not added; PP resin: 87 parts; nano-grade organic modified montmorillonite: 8 parts; composite modifier: 2.0 parts; antioxidant: 0.2 parts; the preparation method is the same as in Example 1.

[0026] Comparative Example 3 This comparative example is based on Example 1 above. The similarities with Example 1 above will not be repeated. In this comparative example, ordinary montmorillonite is used instead of nano-sized organic modified montmorillonite; PP resin: 75 parts; ordinary montmorillonite: 8 parts; maleic anhydride grafted polypropylene: 12 parts; composite modifier: 2.0 parts; antioxidant: 0.2 parts; the preparation method is the same as in Example 1.

[0027] The masterbatches prepared in each embodiment and comparative example were mixed with BOPP base material at an addition amount of 6% to prepare BOPP films with a thickness of 25 μm. The test results are shown in Table 1.

[0028] Table 1

[0029] The above-mentioned test items shall be tested according to the following methods:

[0030] Surface tension: Tested according to GB / T 14216-2008 standard.

[0031] Haze: Tested according to GB / T 2410-2008 standard.

[0032] Tensile properties: tested according to GB / T 1040.3-2006 standard.

[0033] Coefficient of friction: tested according to GB / T 10006-2021 standard.

[0034] Heat shrinkage rate: Measured after treatment at 120°C for 10 minutes.

[0035] As shown in Table 1, the BOPP films prepared in Examples 1 to 3 of this invention all exhibit excellent overall performance. Their surface tension all reach over 43 mN / m, far exceeding that of the comparative samples, while maintaining good optical properties, mechanical properties, and thermal stability. The comparative samples, due to the lack of key components or the use of substitute materials, show significantly inferior performance compared to the examples, which fully demonstrates the importance of the synergistic effect of the components in the formulation of this invention.

[0036] In summary, this invention, through unique formulation design and optimized preparation process, successfully prepared a high surface tension BOPP film masterbatch. This masterbatch not only enables BOPP films to achieve a high surface tension of 42-45 mN / m without corona treatment, fundamentally solving the technical problem of reliance on corona treatment and its diminishing effect in traditional processes, but also, through the synergistic effect of nanoscale organic modified montmorillonite, maleic anhydride-grafted polypropylene, and composite modifiers, significantly improves the film's printability while ensuring comprehensive optimization of its optical, mechanical, and thermal properties. Furthermore, the production process provided by this invention is stable and reliable, easy to scale up, and effectively reduces production costs and energy consumption, aligning with the trend of green manufacturing. It offers the BOPP film industry a high-performance, high-efficiency, and environmentally friendly innovative solution.

[0037] The embodiments described above merely illustrate more specific and detailed implementations of the present invention, and should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A high surface tension masterbatch for BOPP film, characterized in that, It consists of the following raw materials in parts by weight: PP resin: 70-85 parts; Nanoscale organic-modified montmorillonite: 5-12 parts; Maleic anhydride-grafted polypropylene: 8-15 parts; Composite modifier: 1.5~2.5 parts; Antioxidant: 0.1~0.3 parts; The composite modifier is composed of fluorinated surfactant, silane coupling agent and amide slip agent in a weight ratio of 1:(0.5~1.5):(2~3).

2. The high surface tension masterbatch for BOPP film according to claim 1, characterized in that, The nanoscale organic-modified montmorillonite has an interlayer spacing of 2.0~3.5 nm and a specific surface area of ​​500~800 m². 2 / g, and its surface modification adopts a dual modification process: first, it is treated with quaternary ammonium salt intercalation, and then it is modified with silane coupling agent.

3. The high surface tension masterbatch for BOPP film according to claim 1, characterized in that, The maleic anhydride-grafted polypropylene has a grafting rate of 1.2-2.0%, a melt flow rate of 5-10 g / 10 min, and acts as both a compatibilizer and a surface tension enhancer in the masterbatch.

4. The high surface tension masterbatch for BOPP film according to claim 1, characterized in that, The fluorinated surfactant in the composite modifier is a perfluoroalkyl ether, the silane coupling agent is an aminosilane, and the amide slip agent is a complex of erucamide and oleamide, wherein the weight ratio of erucamide to oleamide is 1:(0.8~1.2).

5. The high surface tension masterbatch for BOPP film according to claim 1, characterized in that, The PP resin is a highly crystalline homopolymer polypropylene with an isotacticity greater than 98%, a melt flow rate of 3~6 g / 10 min, and a molecular weight distribution index of 4~6.

6. A method for preparing a high surface tension masterbatch for BOPP film as described in any one of claims 1 to 5, characterized in that, Includes the following steps: (1) Pretreatment: The nano-sized organic modified montmorillonite was vacuum dried at 100~120℃ for 6~8 hours, and the moisture content was controlled to be less than 0.1%; (2) Premixing: PP resin, dried nano-sized organic modified montmorillonite, maleic anhydride grafted polypropylene, composite modifier and antioxidant are added to a high-speed mixer in proportion and a gradient mixing process is adopted: first mix at a low speed of 200~300r / min for 3~5 minutes, and then mix at a high speed of 500~800r / min for 8~12 minutes. (3) Melt blending: The premixed material is added to a co-rotating twin-screw extruder and multi-stage temperature control is adopted: Zone 1 180~190℃, Zone 2 200~210℃, Zone 3 210~220℃, Zone 4 220~230℃, and the die head 225~235℃; (4) Granulation and post-processing: The extruded strip is cooled with water and then cut into pellets. The resulting masterbatch pellets are vacuum dried at 50~70℃ for 4~6 hours.

7. The method for preparing the high surface tension masterbatch for BOPP film according to claim 6, characterized in that, In step (3), the screw configuration of the twin-screw extruder adopts a special combination of mixing elements, including kneading blocks, toothed mixing elements and reverse thread elements, and the screw speed is controlled at 350~450 r / min, the die head pressure is maintained at 15~25 MPa, and the vacuum degree is maintained at ~0.06 to ~0.08 MPa.

8. The method for preparing the high surface tension masterbatch for BOPP film according to claim 6, characterized in that, In step (2), the gradient mixing process used in the premixing step specifically includes: First stage: Mix at 250 r / min for 4 minutes to initially mix the raw materials; Second stage: Mix at 600 r / min for 10 minutes to ensure that all components are thoroughly mixed and homogeneous; Third stage: Mix for 2 minutes at 150 r / min to eliminate static electricity and remove air.

9. The method for preparing the high surface tension masterbatch for BOPP film according to claim 6, characterized in that, In step (3), the residence time of the material during the melt blending process is 45 to 60 seconds, the melt pressure is 18 to 22 MPa, and the melt temperature fluctuation during the extrusion process is controlled within ±2℃.

10. A high surface tension BOPP film, characterized in that, The BOPP film contains a high surface tension masterbatch for BOPP film as described in any one of claims 1 to 5, wherein the high surface tension masterbatch for BOPP film is added to the BOPP film in an amount of 4 to 10 parts by weight, and the BOPP film has a surface tension of 42 to 45 mN / m when it is not subjected to corona treatment.

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