Special material for polypropylene aluminized film and preparation method thereof

Abstract

The present invention discloses a special material for polypropylene aluminized film and its preparation method. The special material comprises: polypropylene resin, a nucleating agent, inorganic particles, and polymer-coated inorganic microspheres. The polymer in the polymer-coated inorganic microspheres is an amphiphilic polymer, and the inorganic particles in the polymer-coated inorganic microspheres are nano-SiO2. By selecting a specific type of transparent nucleating agent to synergize with the polymer-coated inorganic microspheres and nano-inorganic particles, the present invention improves the transparency, thickness uniformity, resistance to small molecule migration and precipitation, and volatility of BOPP film. This special material is suitable for the preparation of high-gloss polypropylene laser aluminized high-end films.

Description

Technical Field

[0001] The invention belongs to the technical field of resin processing and application, and in particular relates to a special material for polypropylene aluminum-plated film and a preparation method thereof. Background Art

[0002] Aluminum-coated film is a flexible packaging material formed by coating an extremely thin layer of metal aluminum on the surface of a plastic film. The functions of aluminization are light-shielding, barrier, and aesthetics. Aluminum-coated film is inexpensive, has excellent performance, and is highly practical. It is widely used in food packaging, medicine, cosmetics, hot stamping materials, laser anti-counterfeiting films, etc.

[0003] Laser aluminized film is a high-tech product within the aluminized film family. It is primarily used for products requiring a high level of appearance, such as trademarks, gifts, decorations, and anti-counterfeiting packaging. Compared to conventional aluminized film, laser aluminized film requires higher transparency, flatness, thermal stability, and physical and mechanical properties. Commonly used laser aluminized film materials include PET, BOPP, and PVC. BOPP offers significant cost advantages over PET and is more stable than PVC, leading to rapid growth in the laser anti-counterfeiting film market.

[0004] At present, the most commonly used processing method for producing aluminum-coated films is vacuum aluminum coating. In order to adapt to the requirements of high-temperature vacuum aluminum coating working conditions, the film material must usually have some necessary basic properties: (1) good stiffness and heat resistance, which can withstand the thermal radiation of the evaporation source and the condensation latent heat of the evaporated material, and can still maintain good dimensional stability and rigidity after evaporation; (2) the film material produces less volatile substances, and the volatilization of small molecules when heated can hinder the movement of aluminum atoms and affect their uniform adhesion; (3) the surface cleanliness of the film material is good, the friction coefficient is moderate, small molecules are precipitated when heated, condensed and deposited on the film surface to form a weak interface layer, which produces a shielding effect, affects the surface tension, and reduces the adhesion of the aluminum coating.

[0005] In addition to the essential basic properties mentioned above, high-end laser aluminum-plated film materials must also possess excellent transparency and flatness to meet the brightness of the aluminum-plated product and ensure the laser holographic effect and clarity. Generally, without changing the polymerization process, the transparency and physical and mechanical properties of the film can be improved by regulating crystallization through the use of nucleating agents. The type of nucleating agent, its compatibility with the resin, and its dispersion in the matrix directly affect the transparency modification effect and may also exacerbate the migration and precipitation of small molecules, affecting the aluminum-plated performance of the film.

[0006] Nucleating agents can be divided into organic small molecules, inorganic small molecules, and polymer nucleating agents according to their main chemical components. Inorganic or polymer nucleating agents have good anti-migration properties, but the former have poor compatibility and dispersibility with PP, and have a shielding effect on light. The transmittance-enhancing effect is difficult to control. Although they are low-cost, their practical applications are limited. Organic small molecule nucleating agents are mainly sorbitol and its derivatives, carboxylic acids and their metal salts, rosin, phosphate nucleating agents, etc. This type of nucleating agent will be accompanied by a certain degree of migration and precipitation. It has little effect on the modification of ordinary PP, but may affect the aluminum plating firmness when modifying aluminum-plated PP. Among them, sorbitol and organic phosphate nucleating agents should be used. The former is a melting type with better nucleation effect, while the latter is a high melting point dispersed type with limited compatibility and dispersibility with the polymer matrix. It is not easy to mix under ordinary processing conditions, which affects the anti-reflection effect. Polymer nucleating agents are polymers with similar structures to PP, such as polyvinylcyclohexane (PVCH), polyethylene pentane, polyvinylcyclosilane, etc. There are currently no commercial products. Literature generally reports that their anti-reflection effect is better than that of organic small molecule nucleating agents, but due to their high melting point characteristics, there may be some uneven dispersion problems under normal processing conditions.

[0007] In addition to examining the transparency enhancement effect of the nucleating agent in the transparent modification of aluminum-grade PP resin, its heat stability, compatibility, and dispersibility should also be fully examined to ensure low thermal mobility of small molecules in the modified resin. The limited transparency enhancement effect of the nucleating agent will result in insufficient brightness in the aluminum-plated product. To ensure good processing properties and film transparency for specialized materials, plasticizers are often added to the base resin to promote the dispersion of the nucleating agent. However, this often exacerbates the migration, precipitation, and volatilization of small molecules, affecting the aluminum-plated performance of the film.

[0008] Invention patent CN 106543553A discloses a special material for aluminum-plated film and its preparation method. It uses a composite nucleating agent to improve the crystallinity of the PP material, thereby improving the product's stiffness. CN 103450556A discloses a method for preparing a special material for polypropylene phase-transmitting nano-scale homopolymer. The permeability of polypropylene is modified by adding specific nucleating agents, nano-calcium carbonate, coupling agents and other additives. However, the uniformity, thermal stability and processing performance of the film material still need to be further improved. CN 111087695 A discloses a high-performance, low-cost polypropylene composite material that is resistant to precipitation and scratches, and a preparation method thereof. It utilizes fumed silica to adsorb and inhibit the migration of an organic light stabilizer, and mentions that fumed silica has an excellent lubricating effect, which can reduce the amount of scratch-resistant additives used. However, the thermal stability, processing properties, and transparency of the film material of this patent application still need to be further improved; in the article "Rheological and Crystallization Behavior of Maleic Anhydride / Styrene Melt-Grafted Random Copolymer Polypropylene", Journal of Chemical Engineering of Colleges and Universities, No. 2 Vol. 31, maleic anhydride / styrene is grafted onto a random copolymer of polypropylene PPR. The long side chains produced by melt grafting act as heterogeneous nucleation, which can increase the crystallization rate of PPR and refine the grains. This method requires the addition of an initiator for melt grafting, and the compatibility of maleic anhydride groups and phenyl groups with PPR is poor, which is not conducive to uniform dispersion. Summary of the Invention

[0009] The main purpose of the present invention is to provide a special material for polypropylene aluminum-plated film and its preparation method, so that the polypropylene aluminum-plated film can ensure transparency while also having the properties of uniform thickness, resistance to thermal migration and precipitation of small molecules, and low volatility.

[0010] In order to achieve the above-mentioned object, the present invention provides a special material for polypropylene aluminum-plated film, which comprises: polypropylene resin, a nucleating agent, inorganic particles and polymer-coated inorganic particle microspheres, wherein the polymer in the polymer-coated inorganic particle microspheres is an amphiphilic polymer, and the inorganic particles in the polymer-coated inorganic particle microspheres are nano-SiO2.

[0011] In one embodiment of the special material for polypropylene aluminum-plated film described in the present invention, the polymer in the polymer-coated inorganic particle microspheres is an amphiphilic polymer containing a polysaturated hydrocarbon chain segment; and / or, the special material comprises 100 parts by weight of polypropylene resin, 0.5-1.5 parts by weight of polymer-coated inorganic particle microspheres, 0.05-0.2 parts by weight of a nucleating agent, and 0.05-0.1 parts by weight of inorganic particles.

[0012] In one embodiment, the polymer-coated inorganic particle microspheres are microspheres obtained by coating nano-SiO2 with a polysaturated hydrocarbon maleic anhydride copolymer, wherein the polysaturated hydrocarbon is a C4-C 10 Obtained by polymerization of olefin monomers.

[0013] In one embodiment of the polypropylene aluminum-plated film material of the present invention, the particle size of the nano-SiO2 is 40-60 nm, and the weight-average molecular weight of the amphiphilic polymer is 50,000-120,000 g / mol.

[0014] In one embodiment of the polypropylene aluminum-plated film special material described in the present invention, the polypropylene resin is a homopolymer polypropylene resin; at 230°C and a 2.16 kg weight, the melt flow rate of the polypropylene resin is 2-3.5 g / 10 min, and the flexural modulus is ≥1500 MPa; the nucleating agent is a transparent polymer nucleating agent or an organic small molecule transparent nucleating agent.

[0015] In one embodiment of the special material for polypropylene aluminum-plated film of the present invention, the nucleating agent is at least one of polycyclohexane ethylene, polyethylene pentane, phosphate metal salt, sorbitol benzyl derivative, and carboxylic acid metal salt.

[0016] In one embodiment of the special material for polypropylene aluminum-plated film of the present invention, the inorganic particles are at least one of nano-SiO2, nano-Y molecular sieve, nano-Beta molecular sieve, and nano-ZSM-5 molecular sieve.

[0017] In one embodiment of the present invention, the polypropylene aluminum-plated film special material has a particle size of 80-150 nm and a specific surface area of ​​200 m 2 / g; the particle size range of nano Y molecular sieve, nano Beta molecular sieve, and nano ZSM-5 molecular sieve is 100-200nm, and the average micropore diameter is greater than

[0018] In order to achieve the above object, the present invention also provides a method for preparing a special material for polypropylene aluminum-plated film, wherein the special material comprises polymer-coated inorganic particle microspheres, and the preparation method of the polymer-coated inorganic particle microspheres comprises the following steps:

[0019] Step 1, copolymerizing maleic anhydride and olefin monomer to obtain a polysaturated hydrocarbon maleic anhydride copolymer PXMA;

[0020] Step 2, reacting a polysaturated hydrocarbon maleic anhydride copolymer with propargyl alcohol to obtain PXMA-C≡CH;

[0021] Step 3: react PXMA-C≡CH with SiO2-N3 to obtain polymer-coated inorganic particle microspheres.

[0022] In one embodiment of the method for preparing the special material for polypropylene aluminum-plated film of the present invention, an initiator is further added in step 1, and the initiator is an azo initiator; in step 3, a sodium ascorbate aqueous solution and divalent copper ions are further added; the olefin monomer is C4-C 10 Olefin monomers.

[0023] The method for preparing the special material for polypropylene aluminized film of the present invention, in one embodiment, comprises:

[0024] The polypropylene resin, the nucleating agent, the inorganic particles and the polymer-coated inorganic particle microspheres are mixed at a high temperature of 90° C. to 110° C., and the mixed materials are discharged after being cooled to room temperature to obtain a mixed raw material;

[0025] The mixed raw materials are placed in an extruder for melt extrusion and granulation. The extruder temperature is 200-230° C. and the screw speed is 200-300 r / min to obtain a special material for polypropylene aluminum-plated film.

[0026] Beneficial effects of the present invention:

[0027] The present invention adds polymer-coated inorganic particle microspheres to homopolymer polypropylene, which can improve the thickness uniformity of the film and further improve the light transmittance uniformity of the film. In addition, the polymer-coated inorganic particle microspheres also have the function of inhibiting the thermal migration of small molecules.

[0028] The polymer-coated inorganic particle microspheres of the present invention have a synergistic effect with the nucleating agent, can further promote the film's transmittance, effectively improve the film's transparency, and significantly improve the processing performance of the special material and the thickness uniformity of the film. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is the reaction equation of PXMA-C≡CH and SiO2-N3 of the present invention. DETAILED DESCRIPTION

[0030] The following is a detailed description of the embodiments of the present invention. These embodiments are implemented based on the technical solutions of the present invention, and detailed implementation methods and processes are given. However, the scope of protection of the present invention is not limited to the following embodiments. The experimental methods for which specific conditions are not specified in the following embodiments are generally based on conventional conditions.

[0031] The invention provides a special material for polypropylene aluminum-plated film, which comprises: polypropylene resin, a nucleating agent, inorganic particles and polymer-coated inorganic particle microspheres, wherein the polymer in the polymer-coated inorganic particle microspheres is an amphiphilic polymer, and the inorganic particles in the polymer-coated inorganic particle microspheres are nano-SiO2.

[0032] The polymer-coated inorganic particle microspheres of the present invention can promote the melt blending and dispersion of additives in the resin matrix, improve the thermal stability of the special material, inhibit the thermal migration and precipitation of small molecules, have a lubricating and plasticizing effect, can improve the thickness uniformity of the film, and improve the processing performance of the special material; and the polymer-coated inorganic particle microspheres of the present invention have a certain heterogeneous nucleation function, have a synergistic effect with the nucleating agent, can further promote the transmittance-enhancing performance of the nucleating agent, and effectively improve the transparency of the film.

[0033] The polymer in the polymer-coated inorganic particle microspheres of the present invention is an amphiphilic polymer, which can improve the dispersibility of the inorganic particles in the polypropylene resin, thereby fully utilizing their nano-properties. In one embodiment, the polymer in the polymer-coated inorganic particle microspheres of the present invention is an amphiphilic polymer containing a polysaturated hydrocarbon chain segment. Compared with a polyunsaturated hydrocarbon chain segment, the polymer-coated inorganic particle microspheres of the present invention can better integrate with the polypropylene resin matrix. Among them, the polysaturated hydrocarbon chain segment refers to a chain segment obtained by the polymerization of olefin monomers without carbon-carbon double bonds, while the polyunsaturated hydrocarbon chain segment refers to a chain segment obtained by the polymerization of olefin monomers that still contains carbon-carbon double bonds.

[0034] In one embodiment, the polymer-coated inorganic particle microspheres of the present invention are microspheres obtained by coating nano-SiO2 with polysaturated hydrocarbon maleic anhydride copolymer, wherein the polysaturated hydrocarbon is C4-C 10 The polysaturated hydrocarbon is obtained by polymerizing olefin monomers, and does not contain carbon-carbon double bonds.

[0035] In another embodiment, the polymer-coated inorganic particle microspheres of the present invention are microspheres obtained by coating nano-SiO2 with isobutylene maleic anhydride copolymer, which can be recorded as SiO2-IBMA, that is, the polymer is isobutylene maleic anhydride copolymer.

[0036] In another embodiment, the particle size of the inorganic particles in the polymer-coated inorganic particle microspheres of the present invention is 40-60 nm, that is, the particle size of nano-SiO2 in the polymer-coated inorganic particle microspheres is 40-60 nm, preferably 40 nm, and the weight-average molecular weight of the amphiphilic polymer is 50,000-120,000 g / mol, preferably 80,000 g / mol.

[0037] In one embodiment, the polypropylene resin of the present invention is a homopolymer polypropylene resin; at 230°C and a weight of 2.16 kg, the melt flow rate of the polypropylene resin is 2-3.5 g / 10 min, and the flexural modulus is ≥1500 MPa, preferably ≥1600 MPa. In another embodiment, the nucleating agent of the present invention is a polymer transparent nucleating agent or an organic small molecule transparent nucleating agent, such as polycyclohexane ethylene, polyethylene pentane, etc., or an organic small molecule transparent nucleating agent, such as a phosphate metal salt, a sorbitol benzyl derivative, a carboxylic acid metal salt, etc. In another embodiment, the nucleating agent of the present invention is polycyclohexane ethylene (PVCH) with a weight average molecular weight M w ≥220000g / mol.

[0038] The inorganic particles of the present invention are at least one of nano-SiO2, nano-Y molecular sieve, nano-Beta molecular sieve, and nano-ZSM-5 molecular sieve. In one embodiment, the inorganic particles of the present invention are a compound of at least one of the nano-molecular sieves and nano-SiO2, i.e., a compound of at least one of the nano-Y molecular sieve, nano-Beta molecular sieve, and nano-ZSM-5 molecular sieve with nano-SiO2. The inorganic particles have good small molecule adsorption properties and also provide a certain lubricating effect. Such a compounding can significantly reduce the small molecule volatiles of PP resin (polypropylene resin), that is, significantly reduce the volatility of additives and oligomers in the PP resin (polypropylene resin).

[0039] In another embodiment, the nano-SiO2 particles used as inorganic particles of the present invention have a particle size of 80-150 nm, preferably 100 nm, and a specific surface area of ​​200 m 2 / g, the particle size range of nano Y molecular sieve, nano Beta molecular sieve, and nano ZSM-5 molecular sieve is 100-200nm, and the average micropore diameter is greater than or equal to In another embodiment, the mass ratio of nano-SiO2 to nano-molecular sieve is 1:1, but the present invention is not limited thereto.

[0040] In one embodiment, the special material for polypropylene aluminum-plated film of the present invention includes 100 parts by weight of polypropylene resin, 0.5-1.5 parts by weight of polymer-coated inorganic particle microspheres, 0.05-0.2 parts by weight of nucleating agent, preferably 0.08-0.1 parts by weight, and 0.05-0.1 parts by weight of inorganic particles.

[0041] Therefore, the present invention provides a special material for polypropylene aluminum-plated film. By using polymer-coated inorganic particle microspheres in conjunction with polymer or organic small molecule nucleating agents and functional nano inorganic particles, the transparency, processability and thermal stability of PP resin can be significantly improved, and the thermal migration and volatilization of small molecules can be effectively reduced, thereby obtaining a highly transparent, easy-to-process and thermally stable PP special material. The film prepared using this special material is uniform and flat, has strong aluminum plating properties, high transparency and stiffness, is suitable for the production of high-gloss laser aluminum-plated high-end films, and is also suitable for the production of ordinary aluminum-plated films and PP transparent films.

[0042] In one embodiment, the present invention further provides a method for preparing polymer-coated inorganic particle microspheres, comprising the following steps:

[0043] Step 1, copolymerizing maleic anhydride and olefin monomer to obtain a polysaturated hydrocarbon maleic anhydride copolymer PXMA;

[0044] Step 2, reacting a polysaturated hydrocarbon maleic anhydride copolymer with propargyl alcohol to obtain PXMA-C≡CH;

[0045] Step 3: react PXMA-C≡CH with SiO2-N3 to obtain polymer-coated inorganic particle microspheres.

[0046] In another embodiment, the reaction of maleic anhydride and an olefin monomer in step 1 is carried out under vacuum. The olefin monomer is a liquid olefin, for example, having 4-10 carbon atoms, more preferably isobutylene. Maleic anhydride is first dissolved in an organic solvent, and then the liquid olefin is introduced. The mixture is heated and stirred to 60-80°C, preferably 70-80°C, and then an initiator is added. The reaction is allowed to proceed for 6-10 hours. Post-processing includes, for example, filtering the reaction mixture, washing and filtering the filter cake multiple times with ethanol, and drying in vacuum at 60-70°C to obtain a white polysaturated hydrocarbon maleic anhydride copolymer PXMA.

[0047] The organic solvent is a mixture of cyclohexane and at least one of acetone, ethyl acetate, and ethanol, preferably a mixture of cyclohexane and acetone, wherein the volume ratio of at least one of acetone, ethyl acetate, and ethanol to cyclohexane is, for example, 1:1. The initiator is, for example, an azo initiator, more specifically, azobisisobutyronitrile (AIBN), and the amount of the initiator added is, for example, 0.01-0.02 wt % of the total reactant mass (including the mass of the solvent, AIBN, maleic anhydride, and olefin monomer).

[0048] In step 2, the reaction of the polysaturated hydrocarbon maleic anhydride copolymer and propargyl alcohol is carried out in an organic solvent, such as N,N-dimethylformamide (DMF). The mass ratio of propargyl alcohol to PXMA is, for example, 5-6.2 g:3-4.5 g. The reaction conditions of the polysaturated hydrocarbon maleic anhydride copolymer and propargyl alcohol are, for example, reflux reaction, and the reflux time is, for example, 24-36 hours. Post-treatment includes vacuum distillation of the reaction mixture, filtration, and repeated washing of the filter cake with acetone, for example, using ultrasonic vibration for 3 minutes each time, filtering, and drying in a vacuum oven at 60-70°C to obtain a white product, PXMA-C≡CH.

[0049] In one embodiment, the reaction equation of isobutylene maleic anhydride copolymer and propargyl alcohol is as follows:

[0050]

[0051] Step 3: The reaction of PXMA-C≡CH with SiO2-N3 is carried out under nitrogen in an organic solvent. SiO2-N3 refers to azidated SiO2. This reaction is a click chemistry reaction between alkynyl and azide groups and can be used for surface grafting of SiO2. The organic solvent is, for example, N,N-dimethylformamide (DMF). The mass ratio of IBMA-CCH to SiO2-N3 is, for example, 0.4-0.9 g:1.8-3 g. During the reaction, copper (I) ions may be added to catalyze the reaction between the alkynyl and azide groups to form a covalent bond. Active copper (I) catalysts can be obtained directly using monovalent copper salts or by reducing divalent copper with sodium ascorbate. A slight excess of sodium ascorbate is added to the reaction to prevent the formation of oxidative coupling products. In one embodiment, the sodium ascorbate aqueous solution and the copper sulfate aqueous solution are used, with the sodium ascorbate aqueous solution having a mass concentration of, for example, 1-1.5 wt%, and the copper sulfate aqueous solution having a mass concentration of, for example, 1-2.5 wt%. In one embodiment, the reaction process is as follows: IBMA-CCH and SiO2-N3 are dispersed in DMF, sodium ascorbate aqueous solution is added, heated to 40-60°C and stirred for 1 hour, then copper sulfate aqueous solution is added, reacted at 80°C for 24-36 hours, filtered, washed with distilled water and tetrahydrofuran in sequence, washed with anhydrous ethanol solution by ultrasonic vibration, and dried in a vacuum oven at 80°C to obtain white solid product SiO2-IBMA nanospheres, i.e., polymer-coated inorganic particle microspheres.

[0052] The core of click chemistry is a new combinatorial chemistry method based on carbon-heteroatom bonding reactions. The "grafting to surface method" to prepare polymer molecular brushes is mostly based on the combination of living free radical polymerization and click chemistry.

[0053] The click chemistry reaction utilized in the present invention is a copper-catalyzed azide / alkyne coupling reaction. First, clickable chains with terminal azide or terminal alkyne are prepared through various active polymers. Then, the substrate is modified with their corresponding clickable groups to prepare polymer molecular brushes through click chemistry reactions.

[0054] The reaction equation of PXMA-C≡CH and SiO2-N3 of the present invention is as follows Figure 1 shown.

[0055] In one embodiment, the method for preparing polymer-coated inorganic particle microspheres of the present invention comprises the following steps:

[0056] Step 1: In a vacuum reaction vessel, maleic anhydride is dissolved in a two-phase mixed solvent of cyclohexane and acetone or ethyl acetate or ethanol (the mass percentage of maleic anhydride in the total reactants is 15-20wt%), liquefied olefin monomer is introduced, and the mixture is heated and stirred to 60-80°C. AIBN is added (the mass percentage of AIBN in the total reactants is 0.01-0.02wt%), and the reaction is completed for 6-10 hours. The mixture is filtered, washed, and dried to obtain a white polysaturated hydrocarbon maleic anhydride copolymer.

[0057] Step 2: Propynol and polysaturated hydrocarbon maleic anhydride copolymer (mass ratio 1.3-2.2) are added to a reactor filled with DMF solvent and heated under reflux for 24-36 hours. After the reaction is completed, vacuum distillation is performed, and the filter cake is repeatedly washed, filtered, and dried to obtain a white product PXMA-C≡CH.

[0058] Step 3: Disperse SiO2-N3 and PXMA-C≡CH3 (mass ratio 2-6) in DMF solvent, replace the air in the reaction system with nitrogen, add sodium ascorbate aqueous solution (mass concentration of 0.01-0.02wt%), heat to 40-60°C and stir for 1h, add copper sulfate aqueous solution (mass concentration of 0.01-0.02wt%), react at 80°C for 24-36h, filter, wash with distilled water, tetrahydrofuran, and anhydrous ethanol in sequence, and dry to obtain white solid product polymer-coated inorganic particle microspheres.

[0059] In one embodiment, the present invention further provides a method for preparing a special material for polypropylene aluminum-plated film, comprising: mixing polypropylene resin, a nucleating agent, inorganic particles, and polymer-coated inorganic particle microspheres at a high temperature of 90° C. to 110° C., and discharging the mixed material after cooling it to room temperature to obtain a mixed raw material;

[0060] The mixed raw materials are placed in an extruder for melt extrusion and granulation. The extruder temperature is 200-230° C. and the screw speed is 200-300 r / min to obtain a special material for polypropylene aluminum-plated film.

[0061] The high mixing time is, for example, 3 minutes to 5 minutes, and the extruder is, for example, a twin-screw extruder.

[0062] In summary, the addition of modified SiO2-PXMA to PP resin significantly improves the material's processing performance, resulting in uniform film thickness. Its synergistic effect with a specific type of transparent nucleating agent promotes enhanced film transparency and significantly inhibits the thermal migration and precipitation of small molecules. The combination of nano-SiO2 and nano-molecular sieves significantly reduces the small volatile molecules in PP resin.

[0063] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0064] In the following examples and comparative examples, each component is weighed according to weight percentage, including: special material for biaxially oriented polypropylene film (BOPP), nucleating agent (PVCH, DBS, NA-11), amphiphilic polymer-coated nanospheres SiO2-PXMA (SiO2-IBMA, SiO2-HXMA, SiO2-OTMA), nano-SiO2, and nano-molecular sieve.

[0065] The MFR of BOPP-1 resin is 3.4 g / 10 min and the flexural modulus is 1700 MPa, while the MFR of BOPP-2 resin is 2.7 g / 10 min and the flexural modulus is 1660 MPa.

[0066] The molecular weight of the raw material IBMA (isobutylene maleic anhydride copolymer) for the preparation of SiO2-IBMA-1 nanoparticles is M w 80000g / mol, the molecular weight of IBMA, the raw material for the preparation of SiO2-IBMA-2 nanospheres w 120000g / mol, the molecular weight of IBMA, the raw material for the preparation of SiO2-IBMA-3 nanospheres w 50000g / mol.

[0067] SiO2-HXMA is 1-hexene maleic anhydride copolymer modified SiO2, and the molecular weight of the raw material 1-hexene maleic anhydride copolymer HXMA is w 60000 g / mol, the particle size of SiO2 is 60 nm.

[0068] SiO2-OTMA is 1-octene maleic anhydride copolymer modified SiO2, and the molecular weight of the raw material 1-octene maleic anhydride copolymer OTMA is w 90000 g / mol, the particle size of SiO2 is 60 nm.

[0069] SiO2-SMA is a styrene maleic anhydride copolymer modified SiO2, and the molecular weight of the raw material styrene maleic anhydride SMA isw 50000 g / mol, the particle size of SiO2 is 40 nm.

[0070] The nucleating agent DBS is dibenzylidene sorbitol, and the nucleating agent NA-11 is sodium 2,2'-methylene-bis(4,6-di-n-butylphenol) phosphate.

[0071] Examples 1 to 5 and Examples 8, 10 to 15

[0072] The components were added into a high-speed mixer and mixed for 5 minutes at a high mixing temperature of 100°C. The mixed materials were cooled to room temperature and then discharged to obtain a mixed raw material. The mixed raw materials were melt-extruded and air-dried into granules through a twin-screw extruder at a screw speed of 250r / min. The temperature of each section of the extruder was set at TC1 200°C, TC2 210°C, TC3~TC8 220°C, TC 10 200℃).

[0073] Example 6

[0074] The components were added into a high-speed mixer and mixed for 5 minutes at a high mixing temperature of 110°C. The mixed materials were cooled to room temperature and then discharged to obtain a mixed raw material. The mixed raw materials were melt-extruded and air-dried into granules through a twin-screw extruder at a screw speed of 300r / min. The temperature of each section of the extruder was set at TC1 200°C, TC2 210°C, TC3~TC8 220°C, TC 10 200℃).

[0075] Example 7 and Example 9

[0076] The components were added into a high-speed mixer and mixed for 5 minutes at a high mixing temperature of 90°C. The mixed materials were cooled to room temperature and then discharged to obtain a mixed raw material. The mixed raw materials were melted and extruded through a twin-screw extruder for air drying and granulation. The screw speed was 250r / min, and the temperature of each section of the extruder was set (TC1 200°C, TC2 210°C, TC3~TC8 220°C, TC 10 200℃).

[0077] Comparative Examples 1-2

[0078] In Comparative Examples 1 and 2, the polypropylene resin pellets were directly cast into films without re-melting and extruding to measure various properties.

[0079] Comparative Examples 3 to 5

[0080] The components were added into a high-speed mixer and mixed for 5 minutes at a high mixing temperature of 100°C. The mixed materials were cooled to room temperature and then discharged to obtain a mixed raw material. The mixed raw materials were melt-extruded and air-dried into granules through a twin-screw extruder at a screw speed of 250r / min. The temperature of each section of the extruder was set at TC1 200°C, TC2 210°C, TC3~TC8 220°C, TC 10 200℃).

[0081] Table 1 Composition of raw materials in Examples 1 to 5 (in parts by weight)

[0082]

[0083] Table 2 Raw material composition of Examples 6 to 10 (in parts by weight)

[0084]

[0085] Table 3 Composition of raw materials of Examples 11 to 15 (in parts by weight)

[0086]

[0087]

[0088] Table 4 Comparative Examples 1-9 Raw Material Composition (in parts by weight)

[0089]

[0090] Performance evaluation methods and implementation standards:

[0091] The haze of the film was measured according to GB / T 2410-2008.

[0092] The film friction coefficient is measured according to GB / T 10006-88.

[0093] The volatile matter was determined according to SH T 1761.1-2008.

[0094] The special materials of each embodiment and comparative example prepared according to the proportion of each component were cast into films under the same processing conditions, and the friction coefficient μ was measured. k0 The film was placed in a vacuum oven at 55°C for 24 hours and its friction coefficient μ was measured again. k :

[0095]

[0096] Table 5 Evaluation results of special materials obtained from examples and comparative examples

[0097]

[0098] Among them, thermal aging of the film will promote the migration and precipitation of small molecules inside the matrix resin, resulting in a change in the friction coefficient. This is related to the small molecule content inside the matrix resin and the thermal stability of the resin. The smaller the rate of change of the friction coefficient, the less small molecules continue to migrate and precipitate during the heating process, indicating that the film has better resistance to small molecule thermal migration. Compared with Example 1 and Comparative Example 4, the difference is that Example 1 adds SiO2-IBMA-1, while Comparative Example 4 adds IBMA, and the amount of nucleating agent PVCH added in Example 1 is half of that in Comparative Example 4. From the evaluation results in Table 5, the anti-reflection effects of Example 1 and Comparative Example 4 are similar, and the μ of Example 1 is 0. k The change rate is relatively low and the volatile matter is also low, indicating that the film of Example 1 releases / volatizes fewer small molecules during the heating process and has better thermal stability, that is, the film has better resistance to small molecule migration under heat.

[0099] Compared with Examples 2, 4 and 3, the amount of SiO2-IBMA added increases successively, and the μ k The rate of change and the average thickness deviation decrease in turn. The volatile matter of Examples 2 and 4 is the same, and the volatile matter of Example 3 is slightly lower, indicating that increasing the amount of SiO2-IBMA added is beneficial to reducing the volatile matter, but the effect is small. However, it will promote the thermal stability of the film, that is, promote the film's resistance to small molecules from thermal migration, and also promote the thickness uniformity of the film.

[0100] In addition, as shown in Table 5, SiO2-IBMA nanospheres have a good synergistic effect with polymer nucleating agents PVCH and organic small molecule nucleating agents (sorbitol DBS, organic phosphate NA-11), which can promote the transparency of the film, inhibit the migration of small molecules, and improve the thickness uniformity of the film. Among them, the crystallization promoting effect on the dispersed nucleating agents PVCH and NA-11 is more obvious, and the transparency of the film is improved more significantly. The anti-small molecule migration property of the resin modified with the melt-type DBS nucleating agent is improved more significantly. With the increase of the SiO2-IBMA component content, the transparency, anti-small molecule thermal migration and thickness uniformity of the film are further improved. The molecular weight M of the modified ligand IBMA is w Changes also affect film properties, molecular weight M w The smaller the size, the more obvious the nanoparticle effect of SiO2-IBMA nanospheres is, the better the transparency and resistance to thermal migration of small molecules of the film are, and the molecular weight M w The larger the value, the better the uniformity of film thickness.

[0101] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims of the present invention.

Claims

1. A special material for polypropylene aluminized film, characterized in that: The special material comprises: 100 parts by weight of polypropylene resin, 0.05 to 0.2 parts by weight of nucleating agent, 0.05 to 0.1 parts by weight of inorganic particles and 0.5 to 1.5 parts by weight of polymer-coated inorganic particle microspheres, wherein the polymer in the polymer-coated inorganic particle microspheres is a polysaturated hydrocarbon maleic anhydride copolymer, and the inorganic particles in the polymer-coated inorganic particle microspheres are nano-SiO2; Among them, polysaturated hydrocarbons are composed of C4-C 10 Obtained by polymerization of olefin monomers.

2. The polypropylene aluminum-plated film special material according to claim 1, characterized in that: The particle size of the inorganic particles in the polymer-coated inorganic particle microspheres is 40-60 nm, and the weight-average molecular weight of the polymer is 50,000-120,000 g / mol.

3. The polypropylene aluminum-plated film special material according to claim 1, characterized in that: The polypropylene resin is a homopolymer polypropylene resin; at 230° C. and a weight of 2.16 kg, the melt flow rate of the polypropylene resin is 2-3.5 g / 10 min, and the flexural modulus is ≥1500 MPa; the nucleating agent is a transparent polymer nucleating agent or an organic small molecule transparent nucleating agent.

4. The polypropylene aluminum-plated film special material according to claim 1, characterized in that: The nucleating agent is at least one of polycyclohexane ethylene, polyethylene pentane, phosphate metal salt, sorbitol benzylidene derivative, and carboxylic acid metal salt.

5. The polypropylene aluminum-plated film special material according to claim 1, characterized in that: The inorganic particles are at least one of nano-SiO2, nano-Y molecular sieve, nano-Beta molecular sieve, and nano-ZSM-5 molecular sieve.

6. The polypropylene aluminum-plated film special material according to claim 5, characterized in that: The nano-SiO2 particle size is 80-150nm, and the specific surface area is ≥200m 2 / g; The particle size range of nano Y-type molecular sieve, nano Beta molecular sieve, and nano ZSM-5 molecular sieve is 100-200nm, and the average micropore diameter is greater than 5.3Å.

7. A method for preparing a special material for polypropylene aluminum-plated film, characterized in that: The special material comprises 100 parts by weight of polypropylene resin, 0.05 to 0.2 parts by weight of a nucleating agent, 0.05 to 0.1 parts by weight of inorganic particles, and 0.5 to 1.5 parts by weight of polymer-coated inorganic particle microspheres. The preparation method of the polymer-coated inorganic particle microspheres comprises the following steps: Step 1, copolymerizing maleic anhydride and olefin monomer to obtain a polysaturated hydrocarbon maleic anhydride copolymer PXMA; Step 2, reacting a polysaturated hydrocarbon maleic anhydride copolymer with propargyl alcohol to obtain PXMA-C≡CH; Step 3: react PXMA-C≡CH with SiO2-N3 to obtain polymer-coated inorganic particle microspheres.

8. The method for preparing a special material for polypropylene aluminized film according to claim 7, characterized in that: In step 1, an initiator is added, and the initiator is an azo initiator; in step 3, an aqueous sodium ascorbate solution and a divalent copper ion are added; the olefin monomer is C4-C 10 Olefin monomers.

9. The method for preparing a special material for polypropylene aluminized film according to claim 7, characterized in that: The preparation method of the special material for polypropylene aluminized film comprises: The polypropylene resin, the nucleating agent, the inorganic particles and the polymer-coated inorganic particle microspheres are mixed at a high temperature of 90° C. to 110° C., and the mixed materials are discharged after being cooled to room temperature to obtain a mixed raw material; The mixed raw materials are placed in an extruder for melt extrusion and granulation. The extruder temperature is 200-230° C. and the screw speed is 200-300 r / min to obtain a special material for polypropylene aluminum-plated film.

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