High-stability antistatic master batch for BOPP (biaxially-oriented polypropylene) film and preparation method of high-stability antistatic master batch

Abstract

The invention discloses a high-stability antistatic master batch for a BOPP (biaxially-oriented polypropylene) film and a preparation method of the high-stability antistatic master batch. The master batch comprises a polypropylene carrier, a core-shell structure composite antistatic agent, a compatilizer, nanoscale SiO2, a stabilizer and a dispersing agent. The preparation method comprises the following steps: firstly, melting and mixing monoglyceride and amide in proportion, and then adding nano SiO2 for high-speed mixing to form a core-shell structure; primarily mixing the polypropylene carrier, the compatilizer, the stabilizer and the dispersing agent; finally, the core-shell structure composite antistatic agent and the primary mixture are subjected to final mixing, and the mixture is subjected to melt extrusion granulation through a double-screw extruder. Through the unique core-shell structure design, the migration rate of the antistatic agent is effectively controlled, so that the prepared BOPP film has lasting and stable antistatic performance, the surface resistance is maintained at 1011-1012 omega, meanwhile, excellent optical performance is maintained, the haze does not exceed 2.0%, and the strict requirements of high-end electronic product packaging are completely met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high molecular materials, and particularly relates to a high-stability antistatic master batch for BOPP film and a preparation method thereof. BACKGROUND

[0002] Biaxially oriented polypropylene (BOPP) film has become an important material in the fields of food, medicine, textile and electronic product packaging due to its excellent optical properties, high tensile strength, good moisture resistance and low manufacturing cost. However, as a typical high polymer insulating material, the volume resistivity of polypropylene is usually greater than 10 15 Ω·cm, and static electricity is easily generated and accumulated due to friction during use. The accumulation of static electricity can cause the film surface to adsorb dust and impurities, affecting the appearance quality of the packaging; in the high-speed packaging process, it may cause poor film running and inaccurate positioning; especially in the field of electronic product packaging, static discharge may also damage sensitive electronic components, causing irreversible loss.

[0003] At present, the main method to improve the antistatic property of BOPP film is to add an antistatic master batch during film preparation. Traditional antistatic master batches mainly rely on small molecule surfactant antistatic agents such as monoglyceride and acylamide compounds. These antistatic agents migrate to the surface of the film to form a conductive layer, absorb moisture in the air and produce an antistatic effect. However, this method has obvious limitations: first, the migration speed of small molecule antistatic agents is difficult to control, and they often precipitate in large quantities in the early stage of film use, resulting in short antistatic effect duration and the formation of an oily layer on the film surface, affecting subsequent printing and compounding processes; second, the compatibility of antistatic agents with the polypropylene matrix is poor, which can cause phase separation during processing, increase the haze of the film and affect the transparency; third, high temperature and shear force during the biaxial stretching process of BOPP film can cause decomposition or uneven distribution of antistatic agents, affecting the performance stability of the final product.

[0004] In the prior art, researchers have tried various methods to improve the durability of the antistatic effect. Some studies have used high molecular permanent antistatic agents such as polyether ester amides, which have solved the migration problem, but the cost is high, and the compatibility with polypropylene is still not ideal, often requiring the addition of a large amount of compatibility agent, which affects the mechanical properties of the film. Another study tried to compound different types of antistatic agents to improve the antistatic effect through synergistic effect, but in practical application, it was found that simple physical mixing cannot achieve controlled release of antistatic agents, and the antistatic effect still decays rapidly over time. Some studies have added inorganic nanoparticles to the master batch to improve dispersion, but the agglomeration of nanoparticles in the matrix has not been effectively solved, which may increase the defect points of the film.

[0005] Therefore, aiming at the above problems, the application provides a high-stability antistatic master batch for BOPP film and a preparation method thereof, by constructing a composite antistatic agent system with a core-shell structure, combining with an optimized formula design and a multi-stage preparation process, controllable migration of the antistatic agent and long-acting antistatic effect are realized, and meanwhile the optical performance and processing stability of the film are ensured. SUMMARY

[0006] The application aims to provide a high-stability antistatic master batch for BOPP film and a preparation method thereof, so as to realize controllable migration of the antistatic agent and long-acting antistatic effect, and meanwhile ensure the optical performance and processing stability of the film.

[0007] The application is achieved by the following technical scheme: A high-stability antistatic master batch for BOPP film is composed of the following raw materials by weight: Polypropylene carrier: 70-95 parts; Core-shell structure composite antistatic agent: 5-15 parts; Compatibility agent: 2-8 parts; Nanoscale SiO2: 0.5-2 parts; Stabilizer: 1-5 parts; Dispersant: 0.5-2 parts.

[0008] Preferably, the polypropylene carrier is a homopolymer polypropylene or a copolymer polypropylene with a melt flow rate of 2-10 g / 10 min (test conditions: 230 DEG C, 2.16 kg load).

[0009] Preferably, the core-shell structure composite antistatic agent is composed of a core material and a shell layer: the core material is a mixture of monoglyceride and acylamide with a weight ratio of 2-3:1, and the purity of monoglyceride and acylamide is both ≥98%; the shell layer is nanometer SiO2 with a particle size of 10-50 nm, and the weight ratio of the core material to the shell layer is (5-10):1.

[0010] Preferably, the compatibility agent is maleic anhydride grafted polypropylene with a grafting rate of 0.8%-1.5%; the dispersant is at least one of a single-terminal carboxyl polyolefin wax or a double-terminal hydroxyl polysiloxane; and the stabilizer is a composite of tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol ester and tri[2,4-di-tert-butylphenyl]phosphite with a mass ratio of 1:1-1:2.

[0011] The application also claims a preparation method of the above high-stability antistatic master batch for BOPP film, comprising the following steps: (1) Core-shell structure pretreatment: the core material of the composite antistatic agent, monoglyceride, and acylamide are preheated to 60-70 DEG C to melt and mix, then nano-SiO2 is added, and the mixture is mixed in a high-speed mixer at a speed of 500-800 rpm for 10-20 minutes to uniformly coat the nano-SiO2 on the antistatic agent to form a core-shell structure; (2) Initial mixing: the polypropylene carrier, compatibilizer, stabilizer, and dispersant are added to a high-speed mixer and mixed at a speed of 300-500 rpm for 5-10 minutes to obtain an initial mixture; (3) Final mixing: the core-shell structure composite antistatic agent obtained in step (1) is added to the initial mixture obtained in step (2) and mixed at a speed of 300-500 rpm for 5-15 minutes to ensure uniform dispersion of the components; (4) Melt extrusion granulation: the uniformly mixed material in step (3) is fed into a twin-screw extruder, and after melt extrusion, water cooling, granulation, and drying, a masterbatch product is obtained.

[0012] Preferably, in step (4), the processing conditions of the twin-screw extruder are: zone 1 temperature 150-160 DEG C, zone 2 temperature 170-180 DEG C, zone 3 temperature 180-190 DEG C, zone 4 temperature 175-185 DEG C, and die temperature 170-180 DEG C; the screw speed is 300-500 r / min; and the feeding frequency is 8-15 Hz.

[0013] Preferably, in step (4), the filter screen group for melt extrusion is configured as a five-layer combination of 80 mesh / 120 mesh / 200 mesh / 120 mesh / 80 mesh to ensure the purity of the melt and the uniformity of dispersion.

[0014] Preferably, during the melt extrusion process in step (4), the melt pressure is controlled at 2.0-2.5 MPa.

[0015] The application also claims to protect the use of the above-mentioned high-stability antistatic masterbatch for BOPP film in BOPP film, and the masterbatch is mixed with the BOPP base material at a weight ratio of 1: (20-30) to produce a BOPP film through a two-way stretching process, and the surface resistance of the film is 1 x 10 11 Ω to 1 x 10 12 Ω.

[0016] The application also claims to protect a BOPP film containing the above-mentioned high-stability antistatic masterbatch for BOPP film, and the mass fraction of the high-stability antistatic masterbatch for BOPP film in the film is 3%-5%.

[0017] Due to the use of the above technical solution, the application has the following beneficial effects compared with the prior art: 1、The application realizes the controllable release of the antistatic component by constructing a unique core-shell structure composite antistatic agent, using the effective physical barrier effect of the nano-SiO2 shell layer on the internal antistatic agent, so that the surface resistance of the BOPP film is stably maintained at 10 11 ~10 12 Ω, the antistatic effect durability is significantly improved, the effective period can reach more than 6 months, and the strict requirements of high-end packaging fields such as electronic products on long-term antistatic performance are completely met; 2、While ensuring excellent antistatic performance, the core-shell structure and the synergistic effect of the dispersant effectively solve the problem of increased haze of the film caused by uneven distribution of components in the traditional antistatic masterbatch, so that the prepared BOPP film maintains excellent optical performance, and the haze is stably controlled below 2.0%, completely meeting the stringent requirements of high-end packaging on material transparency; 3、The formula system of the application significantly improves the processing stability and thermal stability of the masterbatch by combining the composite stabilizer with the precise control of process parameters, ensures that decomposition and deterioration do not occur during high-temperature extrusion and subsequent biaxial stretching processing, and the multi-stage filtration system effectively ensures the purity and consistency of the product, providing reliable protection for large-scale industrial production; 4、The masterbatch provided by the application has excellent compatibility with the existing BOPP film production process, downstream production plants only need to mix the masterbatch with the base material according to the established proportion for direct use, without any modification and adjustment of the existing production equipment and process parameters, greatly reducing the threshold and cost of new technology application, and being conducive to the rapid promotion and industrial application of the product. DETAILED DESCRIPTION

[0018] In order to have a clearer understanding of the technical features, objects and effects of the application, the specific implementation scheme will be described in detail.

[0019] The application will be further described below in combination with examples, but the application is not limited to the following examples. The implementation conditions used in the examples can be further adjusted according to different requirements of specific use, and the implementation conditions marked are the conventional conditions in the industry. The technical features involved in each embodiment of the application can be combined with each other as long as there is no conflict.

[0020] Example 1 The present embodiment provides a high-stability antistatic masterbatch for BOPP film, which is composed of the following raw materials by weight: Polypropylene carrier (melt index 5 g / 10 min): 80 parts; core-shell structure composite antistatic agent: 10 parts (in which monoglyceride: acylamide = 2.5:1, core material and nano-SiO2 weight ratio 8:1); maleic anhydride grafted polypropylene (grafting rate 1.0%): 5 parts; nano-SiO2 (particle size 20 nm): 1 part; composite stabilizer (antioxidant 1010:168 = 1:1): 2 parts; dispersant (single-end carboxyl polyolefin wax): 1 part; The preparation method of the above BOPP film high-stability antistatic master batch includes the following steps: (1) Core-shell structure pretreatment: melt and mix monoglyceride and acylamide to 65°C, then add nano-SiO2, mix in a high-speed mixer at a speed of 600 rpm for 15 minutes to form a core-shell structure; (2) Initial mixing: add polypropylene carrier, maleic anhydride grafted polypropylene, composite stabilizer, and dispersant into a high-speed mixer, mix at a speed of 400 rpm for 8 minutes to obtain an initial mixture; (3) Final mixing: add the core-shell structure composite antistatic agent obtained in step (1) to the initial mixture obtained in step (2), mix at a speed of 400 rpm for 10 minutes; (4) Melt extrusion granulation: feed the mixture into a double screw extruder, set the temperature: zone 1 155°C, zone 2 175°C, zone 3 185°C, zone 4 180°C, die head 175°C; screw speed 400 r / min; feeding frequency 10 Hz; melt pressure control at 2.2 MPa; use 80 mesh / 120 mesh / 200 mesh / 120 mesh / 80 mesh five-layer filter screen combination, water cooling, granulation, drying to obtain the master batch.

[0021] Example 2 The present embodiment provides a BOPP film high-stability antistatic master batch, which is composed of the following raw materials by weight: Polypropylene carrier (melt index 8 g / 10 min): 85 parts; core-shell structure composite antistatic agent: 8 parts (in which monoglyceride: acylamide = 2:1, core material and nano-SiO2 weight ratio 7:1); maleic anhydride grafted polypropylene (grafting rate 1.2%): 4 parts; nano-SiO2 (particle size 30 nm): 0.8 parts; composite stabilizer (antioxidant 1010:168 = 1:1.5): 1.5 parts; dispersant (double-end hydroxyl polysiloxane): 0.8 parts; The preparation method of the above BOPP film high-stability antistatic master batch includes the following steps: (1) Core-shell structure pretreatment: melt and mix monoglyceride and acylamide to 60°C, then add nano-SiO2, mix in a high-speed mixer at a speed of 700 rpm for 12 minutes; (2) Primary mixing: mixing the polypropylene carrier, the compatibilizer, the stabilizer and the dispersant at a rotation speed of 350 rpm for 10 minutes; (3) Final mixing: adding the pre-processed core-shell structure composite antistatic agent into the primary mixture and mixing at a rotation speed of 450 rpm for 8 minutes; (4) Melt extrusion granulation: the temperature of the double-screw extruder is set as follows: zone 1, 158°C; zone 2, 172°C; zone 3, 182°C; zone 4, 178°C; die head, 172°C; screw rotation speed, 350 r / min; feeding frequency, 12 Hz; melt pressure, 2.0 MPa; the five-layer filter screen combination of 80 mesh / 120 mesh / 200 mesh / 120 mesh / 80 mesh is adopted for filtration, and the master batch is obtained through water cooling, granulation and drying.

[0022] Example 3 The present example provides a high-stability antistatic master batch for BOPP film, which is composed of the following raw materials by weight: Polypropylene carrier (melt index 3 g / 10 min): 75 parts; core-shell structure composite antistatic agent: 12 parts (in which monoglyceride: acylamide = 3:1, core material to nano-SiO2 weight ratio 9:1); maleic anhydride grafted polypropylene (grafting rate 0.9%): 6 parts; nano-SiO2 (particle size 40 nm): 1.2 parts; composite stabilizer (antioxidant 1010:168 = 1:2): 2.5 parts; dispersant (single-end carboxyl polyolefin wax): 1.5 parts; The preparation method of the above-mentioned high-stability antistatic master batch for BOPP film comprises the following steps: (1) Core-shell structure pretreatment: melt-mixing monoglyceride and acylamide by preheating to 70°C, and then adding nano-SiO2, mixing in a high-speed mixer at a rotation speed of 550 rpm for 18 minutes; (2) Primary mixing: mixing the polypropylene carrier, the compatibilizer, the stabilizer and the dispersant at a rotation speed of 450 rpm for 6 minutes; (3) Final mixing: adding the pre-processed core-shell structure composite antistatic agent into the primary mixture and mixing at a rotation speed of 380 rpm for 12 minutes; (4) Melt extrusion granulation: the temperature of the double-screw extruder is set as follows: zone 1, 152°C; zone 2, 178°C; zone 3, 188°C; zone 4, 182°C; die head, 178°C; screw rotation speed, 450 r / min; feeding frequency, 8 Hz; melt pressure, 2.4 MPa; the five-layer filter screen combination of 80 mesh / 120 mesh / 200 mesh / 120 mesh / 80 mesh is adopted for filtration, and the master batch is obtained through water cooling, granulation and drying.

[0023] Comparative Example 1 The comparative example is carried out on the basis of the above-mentioned example 1, and the same as the above-mentioned example 1 will not be repeated. The high-stability antistatic masterbatch for BOPP film of the comparative example B is composed of the following raw materials in parts by weight: polypropylene carrier: 80 parts; ordinary mixed antistatic agent (monoglyceride: acylamide = 2.5:1): 10 parts; maleic anhydride grafted polypropylene: 5 parts; composite stabilizer: 2 parts; (not containing nano-SiO2 shell structure, not containing dispersant); Preparation method: all raw materials are added into a high-speed mixer at one time and mixed for 15 minutes, and then extruded and granulated through a double-screw extruder under the same process conditions.

[0024] Comparative example 2 The comparative example is carried out on the basis of the above-mentioned example 1, and the same as the above-mentioned example 1 will not be repeated. The high-stability antistatic masterbatch for BOPP film of the comparative example B is composed of the following raw materials in parts by weight: polypropylene carrier: 80 parts; single antistatic agent (monoglyceride): 10 parts; maleic anhydride grafted polypropylene: 5 parts; composite stabilizer: 2 parts; (using single antistatic agent, not containing core-shell structure); Preparation method: all raw materials are added into a high-speed mixer at one time and mixed for 15 minutes, and then extruded and granulated through a double-screw extruder under the same process conditions.

[0025] The masterbatch obtained in each example and comparative example is mixed with BOPP base material at a weight ratio of 1:25, and a 25μm thick BOPP film is prepared through a two-way stretching process. The test results are shown in Table 1.

[0026] Table 1

[0027] The test standard of the above test items is as follows: Surface resistance: according to ASTM D257-14 "Standard Test Methods for Direct Current Resistance or Conductance of Insulating Materials", measured using a high resistance meter under the conditions of temperature 23±2℃ and relative humidity 50±5%.

[0028] Haze: determined according to ASTM D1003-13 "Standard Test Methods for Haze and Luminous Transmittance of Transparent Plastics" using a haze meter.

[0029] Static friction coefficient: determined according to ASTM D1894-14 "Standard Test Methods for Static and Kinetic Coefficients of Friction of Plastic Film and Sheeting" under standard laboratory conditions as the resistance coefficient when the film starts to slide.

[0030] Dynamic friction coefficient: determined according to ASTM D1894-14 "Standard Test Methods for Static and Kinetic Coefficients of Friction of Plastic Film and Sheeting" under standard laboratory conditions as the resistance coefficient when the film slides at a uniform speed.

[0031] Antistatic durability: by re-measuring the surface resistance of the film sample after storing it in a standard environment of temperature 23±2℃, relative humidity 50±5% for 6 months and calculating the percentage compared with the initial value.

[0032] Migration and precipitation rating: using visual evaluation method, three professional testers independently evaluate and take the average value. The rating standard is: 1st grade (no visible precipitates on the surface), 2nd grade (slight tackiness on the surface), 3rd grade (obvious oily substance on the surface), 4th grade (a large amount of oily precipitates on the surface), 5th grade (severe oily precipitates on the surface and affecting use).

[0033] All tests are carried out in a standard laboratory environment (temperature 23±2℃, relative humidity 50±5%) to ensure the accuracy and comparability of test data. Each sample is tested in parallel for 5 times, and the average value is taken as the final result.

[0034] As can be seen from Table 1, the BOPP film prepared from the masterbatch prepared in Examples 1-3 of the present application is significantly superior to the comparative examples in terms of antistatic performance, optical performance and durability. Especially the antistatic durability index, the examples remain above 92%, while comparative example 1 is only 65%, and comparative example 2 is as low as 45%, fully proving the significant effect of the core-shell structure in controlling the migration of antistatic agents. At the same time, the haze values of the examples are all lower than 2.0%, far superior to the comparative examples, indicating that the present application has obvious advantages in maintaining the transparency of the film.

[0035] In summary, by constructing a core-shell structure composite antistatic agent, optimizing the formulation system and preparation process, the present application successfully develops a high-performance antistatic masterbatch for BOPP film, which has the advantages of stable and durable antistatic performance (surface resistance stable at 10 11 ~10 12 Ω, effective period more than 6 months), excellent optical properties (haze ≤2.0%), excellent processing stability and product consistency, and is fully compatible with the existing production process, without the need for equipment modification, can be directly applied, effectively solving the technical problem that the traditional antistatic masterbatch is difficult to balance between durability, transparency and processability, and providing an ideal material solution for high-end electronic product packaging.

[0036] The above-described examples only express the more specific and detailed implementation of the present application, but should not be construed as limiting the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the scope of protection of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. A high stability antistatic masterbatch for BOPP film, characterized in that, consists of the following raw materials by weight: polypropylene carrier: 70~95 parts; core-shell structure composite antistatic agent: 5~15 parts; compatibility agent: 2~8 parts; nanoscale SiO2: 0.5~2 parts; stabilizer: 1~5 parts; dispersant: 0.5~2 parts.

2. The high stability antistatic masterbatch for BOPP film according to claim 1, characterized in that, The polypropylene carrier is a homopolymer polypropylene or a copolymer polypropylene with a melt flow rate of 2~10 g / 10 min.

3. The high stability antistatic masterbatch for BOPP film according to claim 1, wherein The core-shell structure composite antistatic agent consists of a core material and a shell layer: the core material is a mixture of monoglyceride and acylamide in a weight ratio of (2~3):1, and the purity of both monoglyceride and acylamide is ≥98%; the shell layer is nanoscale SiO2 with a particle size of 10~50 nm, and the weight ratio of core material to shell layer is (5~10):

1.

4. The high stability antistatic masterbatch for BOPP film according to claim 1, wherein The compatibility agent is maleic anhydride grafted polypropylene with a grafting rate of 0.8%~1.5%; the dispersant is at least one of a single-terminal carboxyl polyolefin wax or a double-terminal hydroxyl polysiloxane; and the stabilizer is a compound of tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol ester and tri[2,4-di-tert-butylphenyl]phosphite in a mass ratio of 1:1~1:

2.

5. The method of producing a high stability antistatic master batch for BOPP film according to any one of claims 1 to 4, characterized in that, The method comprises the following steps: (1) Core-shell structure pretreatment: preheat the core material monoglyceride and acylamide of the composite antistatic agent to 60~70℃ for melt mixing, then add nanoscale SiO2, and mix in a high-speed mixer at a speed of 500~800 rpm for 10~20 minutes to uniformly coat the nanoscale SiO2 on the antistatic agent, forming a core-shell structure; (2) Initial mixing: add the polypropylene carrier, compatibility agent, stabilizer, and dispersant into a high-speed mixer, and mix at a speed of 300~500 rpm for 5~10 minutes to obtain an initial mixture; (3) Final mixing: add the core-shell structure composite antistatic agent obtained in step (1) into the initial mixture obtained in step (2), and mix at a speed of 300~500 rpm for 5~15 minutes to ensure uniform dispersion of the components; (4) Melt extrusion granulation: feed the uniformly mixed material in step (3) into a double-screw extruder, and after melt extrusion, water cooling, granulation, and drying, obtain the masterbatch product.

6. The process for preparing high stability antistatic masterbatch for BOPP film as claimed in claim 5 wherein, In step (4), the processing conditions of the double-screw extruder are as follows: zone 1 temperature 150~160℃, zone 2 temperature 170~180℃, zone 3 temperature 180~190℃, zone 4 temperature 175~185℃, and die head temperature 170~180℃; screw speed 300~500 r / min; and feeding frequency 8~15 Hz.

7. The process for preparing high stability antistatic masterbatch for BOPP film as claimed in claim 5 wherein, the process is carried out at a temperature in the range of 120°C to 140°C. In step (4), the filter screen group for melt extrusion is configured as five layers of 80 mesh / 120 mesh / 200 mesh / 120 mesh / 80 mesh to ensure melt purity and uniform dispersion.

8. The process for preparing high stability antistatic masterbatch for BOPP film as claimed in claim 5 wherein, In the melt extrusion process in step (4), the melt pressure is controlled at 2.0~2.5 MPa.

9. Use of the high stability antistatic masterbatch for BOPP film according to any one of claims 1 to 4 in BOPP film, characterized in that, The master batch is mixed with BOPP base material in a weight ratio of 1: (20-30), and then a BOPP film is prepared through a two-way stretching process, and the surface resistance of the film is 1 x 10 11 Ω to 1 x 10 12 Ω.

10. A BOPP film characterized in that, The masterbatch contains the masterbatch of any one of claims 1~4, and the mass fraction of the masterbatch in the film is 3%~5%.

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