Composite co-agents, methods of making, and polypropylene aluminized film substrates made therefrom

Abstract

This invention provides a composite additive for a polypropylene aluminized film substrate. The composite additive comprises the following components by weight: 0.1-5 parts by weight of antioxidant, 0.1-5 parts by weight of opening agent, 0.1-5 parts by weight of nucleating agent, 0.1-1 parts by weight of deacidifying agent, and 0.1-5 parts by weight of polyolefin resin; wherein the polyolefin resin includes one or both of vinyl elastomers and propylene elastomers. By adding an elastomer-containing polyolefin resin to the composite additive, this invention effectively promotes surface crystallization of the polypropylene film, thereby achieving excellent adhesion properties. Furthermore, by adding an elastomer-containing polyolefin resin, the processing adaptability of the composite additive under different shear strengths is improved, resulting in excellent dispersion effects in the polypropylene substrate.

Description

Technical Field

[0001] This invention relates to the field of polypropylene aluminized film technology, specifically to composite additives and their preparation methods, and polypropylene aluminized film substrates prepared therefrom. Background Technology

[0002] Cast polypropylene film (CPP) is an unstretched polypropylene film produced by the casting process. It features good transparency, high gloss, good stiffness, good moisture barrier properties, excellent heat resistance, and ease of heat sealing. Furthermore, its stiffness and suitability for packaging machinery are superior to polyethylene film, giving it a significant position in the packaging film industry. CPP suitable for food and pharmaceutical packaging requires both low heat-sealing temperature and high barrier properties. Metallization of the film can enhance its performance. Vacuum metallization involves depositing an aluminum film onto a surface-treated CPP aluminized substrate, resulting in a metallized film with a bright appearance, high metallization strength, environmental friendliness, and excellent barrier properties. The use of high-barrier metallized films in food packaging can effectively slow down food spoilage. In pharmaceutical packaging, it meets pharmaceutical requirements, preventing spoilage of drugs and medical devices due to packaging issues and reducing usage risks.

[0003] The performance of CPP metallized films is mainly affected by the film substrate, and the surface tension of the corona layer affects the adhesion of the metallized film. Studies have shown that adding a small amount of other polyolefin resins to PP can improve the surface tension of the cast film while maintaining the original properties of PP. However, PP and other polyolefin resins have poor compatibility due to differences in molecular structure, resulting in weak interfacial adhesion. Under low mixing strength, this may lead to poor dispersibility and agglomeration of other additives, causing defects on the film surface. In addition to affecting the film appearance, the occurrence of surface defects can further reduce the surface metallization effect, such as uneven aluminum layer and decreased adhesion.

[0004] Therefore, there is an urgent need to develop a composite additive for a high-purity, low-crystal-point polypropylene aluminized film substrate and a polypropylene aluminized film substrate prepared therefrom. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and to provide a composite additive for polypropylene aluminized film substrate. The aim is to improve the adhesion between the substrate film surface and the aluminum layer, while improving the processing adaptability of the composite additive under different shear intensities, thereby providing a polypropylene aluminized film substrate that is easy to process, has low surface defects, and high aluminized adhesion.

[0006] To achieve the above objectives, the first aspect of the present invention provides a composite additive for a polypropylene aluminized film substrate, the composite additive comprising the following components: 0.1-5 parts by weight of antioxidant, 0.1-5 parts by weight of opening agent, 0.1-5 parts by weight of nucleating agent, 0.1-1 parts by weight of deacidifying agent, and 0.1-5 parts by weight of polyolefin resin; wherein the polyolefin resin comprises one or both of vinyl elastomer and propylene elastomer.

[0007] This invention significantly enhances the performance of the composite additive in promoting surface crystallization of the substrate film by incorporating a polyolefin resin containing an elastomer, particularly a vinyl elastomer and / or a propylene-based elastomer. This effectively promotes surface crystallization of the polypropylene film, increasing its surface crystallinity and resulting in excellent adhesion. Furthermore, the addition of the elastomer-containing polyolefin resin improves the processing adaptability of the composite additive under different shear strengths, giving it excellent dispersion in the polypropylene substrate and effectively avoiding surface defects caused by poor dispersion. Further adjustments to the amounts of antioxidants, opening agents, nucleating agents, deacidifying agents, and polyolefin resin in the composite additive, at the aforementioned proportions, allow the components to synergistically achieve even higher surface crystallinity in the polypropylene aluminized film substrate, thus further improving adhesion.

[0008] In some embodiments of the present invention, the polyolefin resin further includes polyethylene and / or polybutene-1.

[0009] In some embodiments of the present invention, the polyolefin resin is a mixture of polyethylene and vinyl elastomer and / or propylene elastomer, wherein the mass ratio of the polyethylene to the vinyl elastomer and / or propylene elastomer is 1:(0.1-5).

[0010] In some embodiments of the present invention, the polyethylene is selected from one or more of linear low-density polyethylene, low-density polyethylene, and high-density polyethylene; the melt index of the polyethylene at 190°C and a load of 2.16 kg is 0.5-30 g / 10 min, and the density is 0.910-0.980 g / cm³. 3 .

[0011] In some embodiments of the present invention, the polybutene-1 has a melt index of 0.5-30 g / 10 min at 190°C and a load of 2.16 kg, and a density of 0.890-0.910 g / cm³. 3 .

[0012] In some embodiments of the present invention, the vinyl elastomer has a melt index of 0.5-30 g / 10 min and a density of 0.80-0.90 g / cm³ at 190°C and a load of 2.16 kg. 3 .

[0013] In some embodiments of the present invention, the propylene-based elastomer has a melt index of 0.5-30 g / 10 min and a density of 0.80-0.90 g / cm³ at 230°C and a load of 2.16 kg. 3 .

[0014] In some embodiments of the present invention, the vinyl elastomer comprises ethylene structural units and α-olefin structural units, wherein the monomers corresponding to the α-olefin structural units comprise one or more of butene, pentene, nonene, hexene, and octene, and the weight content of the α-olefin structural units in the vinyl elastomer is 20%-50%.

[0015] In some embodiments of the present invention, the vinyl elastomer is an ethylene-octene copolymer, and the content of the octene structural units is 20%-35%.

[0016] In some embodiments of the present invention, the propylene-based elastomer comprises propylene structural units and one or more selected from ethylene structural units and α-olefin structural units, wherein the monomer corresponding to the α-olefin structural unit comprises one or more selected from butene, pentene, nonene, hexene and octene, and the weight content of ethylene structural units and α-olefin structural units in the propylene-based elastomer is 0.1%-20%.

[0017] In some embodiments of the present invention, the propylene-based elastomer is a propylene-ethylene copolymer, and the content of the ethylene structural unit is 0.5%-15%.

[0018] In this invention, the propylene-based elastomer contains a large number of propylene segments, which have good compatibility with polypropylene raw materials. The ethylene structural units contained in the propylene-based elastomer attract each other with polyethylene, which not only provides polarity to the polypropylene raw materials but also increases the compatibility between polyethylene and polypropylene raw materials, improves the problem of agglomeration of other additives caused by phase separation, and avoids the exposure of defects in the next stage of the casting film process.

[0019] In some embodiments of the present invention, the antioxidant is selected from one or more of phosphite antioxidants, hindered phenolic antioxidants, and hydroxylamine antioxidants.

[0020] In some embodiments of the present invention, the antioxidant is a mixture of phosphite antioxidant and hindered phenolic antioxidant, wherein the mass ratio of the phosphite antioxidant to the hindered phenolic antioxidant is 1:(0.1-10).

[0021] In some embodiments of the present invention, the nucleating agent is selected from one or more of sorbitol-based nucleating agents, organophosphate nucleating agents, rosin-based nucleating agents, hydroxy acids and their metal salts nucleating agents, and inorganic nucleating agents.

[0022] In some embodiments of the present invention, the nucleating agent is a sorbitol-based nucleating agent.

[0023] In some embodiments of the present invention, the sorbitol nucleating agent includes one or more of di(3,4-dimethyldibenzyl)sorbitol, dibenzyl sorbitol, and bis[2,2'-methylene-bis(4,6-di-tert-butylphenyl)phosphate]aluminum hydroxyl.

[0024] The nucleating agent in this invention has poor compatibility with polypropylene, easily migrates to the surface of the film, and can enhance the mobility of polypropylene molecular chains, enabling the polypropylene molecular chains to be arranged regularly on the surface, thereby improving the crystallinity of the film surface and achieving strong adhesion between the film and aluminum.

[0025] In some embodiments of the present invention, the opening agent is selected from organic opening agents or inorganic opening agents.

[0026] In some embodiments of the present invention, the opening agent is selected from one or more of silica, talc, diatomaceous earth, oleamide, and erucamide.

[0027] In some embodiments of the present invention, the acid remover is selected from one or more of hydrotalcite, zinc stearate, calcium stearate, calcium hydroxide, and sodium hydroxide.

[0028] The second aspect of the present invention provides a method for preparing a composite additive, comprising the following steps: mixing an antioxidant, an opening agent, a nucleating agent, an acid remover, and a polyolefin resin, followed by high-temperature melt extrusion molding and pelletizing to obtain the composite additive.

[0029] In some embodiments of the present invention, the high-temperature melt extrusion molding is performed using a single-screw extruder or a twin-screw extruder.

[0030] In some embodiments of the present invention, the pelletizing is performed by strip-type air-cooled pelletizing or water ring pelletizing.

[0031] In some embodiments of the present invention, the length-to-diameter ratio of the single screw extruder is 5:1-20:1, and the extrusion temperature is 80-200°C.

[0032] In some embodiments of the present invention, the length-to-diameter ratio of the twin-screw extruder is 10:1-40:1, and the extrusion temperature is 80-200°C.

[0033] Through extensive experimentation, the inventors discovered that the composite additive in this invention, when used after low-temperature kneading and shaping, exhibits poor adaptability to varying shear strengths caused by different process parameters during the preparation of polypropylene metallized film substrates. This significantly reduces the mixing and extrusion effect of the composite additive and polypropylene powder under weak shear conditions, further affecting the substrate's processing performance in the casting process and leading to defects on the film's surface. These defects can also cause uneven aluminum layering and localized aluminum layer peeling during subsequent metallization, resulting in product quality issues.

[0034] In this invention, a high-temperature melting process is introduced, and a suitable length-to-diameter ratio of the extruder is selected during single-screw extrusion or twin-screw extrusion to prepare the composite additive of this invention. This can effectively improve the mixing effect between different components inside the composite additive, thereby enhancing the processing adaptability of the composite additive when it is mixed and extruded with polypropylene powder. The dispersion effect of the composite additive in the powder is further improved, effectively avoiding the problem of film surface defects after polypropylene aluminized film substrate is processed by the casting process.

[0035] A third aspect of the present invention provides a polypropylene aluminized film substrate, comprising the following raw materials in parts by weight:

[0036] 80-99.99 parts by weight of polypropylene powder and 0.01-20 parts by weight of the above-mentioned composite additives.

[0037] In some embodiments of the present invention, the polypropylene powder is selected from homopolymer polypropylene or random copolymers of propylene with ethylene and / or α-olefins.

[0038] In some embodiments of the present invention, the melt index of the polypropylene powder at 230°C and 2.16 kg load is 1-20 g / 10 min.

[0039] In some embodiments of the present invention, the weight content of ethylene structural units and / or α-olefin structural units in the random copolymer is 0.1% to 20%.

[0040] A fourth aspect of this invention provides a method for preparing a polypropylene aluminized film substrate, comprising the following steps:

[0041] After the polypropylene powder and composite additives are mixed evenly, they are extruded and pelletized by twin screw extrusion to obtain polypropylene aluminized film substrate.

[0042] In some embodiments of the present invention, the extrusion temperature is 180–250°C, and pelleting is performed by strip-type air-cooled pelleting or water ring pelleting.

[0043] The technical solution provided by this invention has the following beneficial effects:

[0044] 1. This invention significantly enhances the performance of the composite additive in promoting surface crystallization of the substrate film by adding a polyolefin resin containing an elastomer, particularly a polyolefin resin containing a vinyl elastomer and / or a propylene elastomer, thereby effectively promoting surface crystallization of the polypropylene film, increasing its surface crystallinity, and thus obtaining excellent adhesion properties. Furthermore, by adding a polyolefin resin containing an elastomer, the processing adaptability of the composite additive under different shear strengths is improved, enabling the composite additive to have excellent dispersion effect in the polypropylene substrate, effectively avoiding film surface defects caused by poor dispersion of the additive.

[0045] 2. By adjusting the amount of antioxidants, opening agents, nucleating agents, deacidifying agents and polyolefin resins added to the composite additives, the components in the composite additives work together to achieve a higher surface crystallinity for the polypropylene aluminized film substrate under the above proportions. Only a small proportion of composite additives is needed to effectively improve the adhesion between the substrate film and the aluminized layer.

[0046] 3. The composite additive preparation method provided by the present invention produces a composite additive with excellent dispersion effect in polypropylene substrate, which can effectively avoid the problem of film surface defects caused by poor dispersion effect of the additive.

[0047] 4. The polypropylene aluminized film substrate provided by this invention is easy to scale up for industrial production, has a simple production process, and can be applied to the aluminized film preparation process without requiring adjustment of process parameters, making it highly applicable. Attached Figure Description

[0048] The invention will now be further described with reference to the accompanying drawings.

[0049] Figure 1 This is a test image of the aluminum plating residue in Example 7;

[0050] Figure 2 This is a test image of the aluminum plating residue in Example 8;

[0051] Figure 3 This is a test image of the aluminum plating residue in Example 9;

[0052] Figure 4 This is a test image of the aluminum plating residue in Example 10;

[0053] Figure 5 This is a test image of the aluminum plating residue in Example 11;

[0054] Figure 6 This is a test image of the aluminum plating residue in Example 12;

[0055] Figure 7 This is a test image showing the residual aluminum coating in Comparative Example 1.

[0056] Figure 8 This is a test image of the aluminum plating residue in Comparative Example 2;

[0057] Figure 9 This is a test image of the residual aluminum coating in Comparative Example 3. Detailed Implementation

[0058] To make the present invention easier to understand, the present invention will be described in detail below with reference to embodiments. These embodiments are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention. Unless otherwise specified, specific conditions in the embodiments are performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the materials used in the embodiments are commercially available products or conventional products that can be synthesized by known methods.

[0059] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0060] Example 1

[0061] Preparation of composite additives:

[0062] 1.8 parts by weight of antioxidant, 2.6 parts by weight of opening agent, 1.8 parts by weight of nucleating agent, 0.2 parts by weight of acid remover, and 3.6 parts by weight of polyolefin resin were mixed evenly. The mixture was then melt-extruded at 150°C through a twin-screw extruder with a length-to-diameter ratio of 25:1 and pelletized using a water ring milling process to obtain a composite additive for polypropylene aluminized film substrate.

[0063] The polyolefin resin comprises 2.1 parts by weight of high-density polyethylene and 1.5 parts by weight of propylene-based elastomer.

[0064] The melt flow index of high-density polyethylene at 190℃ and 2.16 kg load is 8.0 g / 10 min, and its density is 0.960 g / cm³. 3 .

[0065] The propylene-based elastomer is a propylene-ethylene copolymer with a melt index of 12.0 g / 10 min and a density of 0.865 g / cm³ at 230 °C and a load of 2.16 kg. 3 The weight content of ethylene structural units is 13%.

[0066] The antioxidant is a combination of phosphite antioxidant and hindered phenolic antioxidant in a mass ratio of 1:1;

[0067] The opening agent is silica with a particle size of 4.67 μm;

[0068] The nucleating agent is di(3,4-dimethyldibenzyl)sorbitol;

[0069] The acid remover is hydrotalcite with a particle size of 0.56 μm.

[0070] Examples 2-6

[0071] Unlike Example 1, the raw materials and their proportions for preparing the composite additives in Examples 2-6 are different, as detailed in Table 1.

[0072] Table 1

[0073]

[0074] The polyethylene in Table 1 is high-density polyethylene, with a melt index of 8.0 g / 10 min and a density of 0.960 g / cm³ at 190℃ and a load of 2.16 kg. 3 .

[0075] The polybutene-1 in Table 1 has a melt index of 10.0 g / 10 min and a density of 0.906 g / cm³ at 190 °C and a load of 2.16 kg. 3 .

[0076] The vinyl elastomers in Table 1 are ethylene-octene copolymers with a melt index of 13.0 g / 10 min and a density of 0.863 g / cm³ at 190 °C and a load of 2.16 kg. 3 The weight content of octene structural units is 32%.

[0077] The propylene-based elastomers in Table 1 are propylene-ethylene copolymers with a melt index of 12.0 g / 10 min and a density of 0.865 g / cm³ at 230 °C and a load of 2.16 kg. 3 The weight content of ethylene structural units is 13%.

[0078] The antioxidants in Table 1 are a combination of phosphite antioxidants and hindered phenolic antioxidants in a mass ratio of 1:1;

[0079] The opening agent in Table 1 is silica with a particle size of 4.67 μm;

[0080] The nucleating agent in Table 1 is di(3,4-dimethyldibenzyl)sorbitol;

[0081] The hydrotalcite particle size in Table 1 is 0.56 μm; the calcium hydroxide particle size is 9.5 μm.

[0082] Example 7

[0083] Preparation of polypropylene aluminized film substrate:

[0084] 99.4 parts by weight of polypropylene powder and 0.6 parts by weight of the composite additive prepared in Example 1 were mixed evenly. The mixture was then extruded at 230°C using a twin-screw extruder and cut into pellets by air cooling to obtain a polypropylene aluminized film substrate.

[0085] The polypropylene powder is a random copolymer polypropylene with a melt index of 8.0 g / 10 min and an ethylene structural unit weight content of 3% prepared by the Spheripol loop process at 230℃ and 2.16 kg load.

[0086] Examples 8-12

[0087] Unlike Example 7, Examples 8-12 used the composite additives prepared in Examples 2-6, and adjusted the ratio of polypropylene powder to composite additives accordingly, as detailed in Table 2.

[0088] Table 2

[0089]

[0090] The polypropylene powder in Table 2 is a random copolymer polypropylene with a melt index of 8.0 g / 10 min and an ethylene structural unit weight content of 3% prepared by the Spheripol loop process at 230℃ and 2.16 kg load.

[0091] Comparative Example 1

[0092] Preparation of composite additives:

[0093] 1.8 parts by weight of antioxidant, 2.6 parts by weight of opening agent, 1.8 parts by weight of nucleating agent and 0.2 parts by weight of deacidifying agent are mixed evenly. The mixture is then melt-extruded at 150°C through a twin-screw extruder with a length-to-diameter ratio of 25:1 and pelletized using a water ring milling process to obtain a composite additive for polypropylene aluminized film substrate.

[0094] The antioxidant is a combination of phosphite antioxidant and hindered phenolic antioxidant in a mass ratio of 1:1;

[0095] The opening agent is silica with a particle size of 4.67 μm;

[0096] The nucleating agent is di(3,4-dimethyldibenzyl)sorbitol;

[0097] The acid remover is hydrotalcite with a particle size of 0.56 μm.

[0098] Preparation of polypropylene aluminized film substrate:

[0099] 99.4 parts by weight of polypropylene powder and 0.6 parts by weight of composite additive prepared by Comparative Example 1 were mixed evenly. The mixture was then extruded at 230°C using a twin-screw extruder and cut into pellets by air cooling to obtain a polypropylene aluminized film substrate.

[0100] The polypropylene powder is a random copolymer polypropylene prepared by the Spheripol loop process with a melt index of 8.0 g / 10 min at 230°C under a load of 2.16 kg and an ethylene structural unit weight content of 3%.

[0101] Comparative Example 2

[0102] Preparation of composite additives:

[0103] 1.8 parts by weight of antioxidant, 2.6 parts by weight of opening agent, 1.8 parts by weight of nucleating agent, 0.2 parts by weight of deacidifying agent and 2.1 parts by weight of high-density polyethylene are mixed evenly. The mixture is then melt-extruded at 150°C through a twin-screw extruder with a length-to-diameter ratio of 25:1 and pelletized using a water ring milling process to obtain a composite additive for polypropylene aluminized film substrate.

[0104] The antioxidant is a combination of phosphite antioxidant and hindered phenolic antioxidant in a mass ratio of 1:1;

[0105] The opening agent is silica with a particle size of 4.67 μm;

[0106] The nucleating agent is di(3,4-dimethyldibenzyl)sorbitol;

[0107] The acid remover is hydrotalcite with a particle size of 0.56 μm;

[0108] The melt flow index of high-density polyethylene at 190℃ and 2.16 kg load is 8.0 g / 10 min, and its density is 0.960 g / cm³. 3 .

[0109] Preparation of polypropylene aluminized film substrate:

[0110] 99.4 parts by weight of polypropylene powder and 0.6 parts by weight of composite additive prepared by Comparative Example 2 were mixed evenly. The mixture was then extruded at 230°C using a twin-screw extruder and cut into pellets by air cooling to obtain a polypropylene aluminized film substrate.

[0111] The polypropylene powder is a random copolymer polypropylene prepared by the Spheripol loop process with a melt index of 8.0 g / 10 min at 230°C under a load of 2.16 kg and an ethylene structural unit weight content of 3%.

[0112] Comparative Example 3

[0113] Preparation of composite additives:

[0114] 1.8 parts by weight of antioxidant, 2.6 parts by weight of opening agent, 1.8 parts by weight of nucleating agent, 0.2 parts by weight of acid remover, and 3.6 parts by weight of polyolefin resin were mixed evenly. The mixture was then extruded at 40°C through a single screw extruder with a length-to-diameter ratio of 7:1 and granulated by air cooling to obtain a composite additive for polypropylene aluminized film substrate.

[0115] The polyolefin resin comprises 2.1 parts by weight of high-density polyethylene and 1.5 parts by weight of propylene-based elastomer.

[0116] The melt flow index of high-density polyethylene at 190℃ and 2.16 kg load is 8.0 g / 10 min, and its density is 0.960 g / cm³. 3 .

[0117] The propylene-based elastomer is a propylene-ethylene copolymer with a melt index of 12.0 g / 10 min and a density of 0.865 g / cm³ at 230 °C and a load of 2.16 kg. 3 The content of ethylene structural units is 13%.

[0118] The antioxidant is a combination of phosphite antioxidant and hindered phenolic antioxidant in a mass ratio of 1:1;

[0119] The opening agent is silica with a particle size of 4.67 μm;

[0120] The nucleating agent is di(3,4-dimethyldibenzyl)sorbitol;

[0121] The acid remover is hydrotalcite with a particle size of 0.56 μm.

[0122] Preparation of polypropylene aluminized film substrate:

[0123] 99.4 parts by weight of polypropylene powder and 0.6 parts by weight of composite additive prepared by Comparative Example 3 were mixed evenly. The mixture was extruded by twin screw extrusion at 230°C and granulated by air cooling to obtain polypropylene aluminized film substrate.

[0124] The polypropylene powder is a random copolymer polypropylene prepared by the Spheripol loop process with a melt index of 8.0 g / 10 min at 230°C under a load of 2.16 kg and an ethylene structural unit weight content of 3%.

[0125] Test case

[0126] Preparation of aluminized single-layer polypropylene film: Aluminized polypropylene film substrates from Examples 7-12 and Comparative Examples 1-3 were cast into films at screw temperatures of 190-240°C and cold roll temperatures of 26-33°C to obtain a single-layer polypropylene film with an average thickness of 30 μm. The thickness was determined from the residual aluminized layer test. Figure 1-9 As can be seen, the single-layer polypropylene films of Comparative Examples 1-3 have obvious defects on their surface, with particles present; conversely, no obvious defects appear in Examples 7-12.

[0127] The test method for fisheye membranes is based on Q / SH 3065014.

[0128] The polypropylene film was surface-treated using a plasma cleaner with a plasma strength of 110W and an air treatment time of 5 seconds.

[0129] Surface wetting tension test: Diane solutions with different wetting tensions are coated onto the surface of the surface-treated film. The liquid film formed by the dyne solution is observed under light, and the time it takes for the liquid film to disperse from a continuous state to small droplets is recorded. If the liquid film lasts for more than 2 seconds, the experiment is repeated on a new sample using a dyne solution with a higher wetting tension; otherwise, the wetting tension is reduced. The dyne solution with the closest wetting tension to 2 seconds is used for at least 3 measurements, and the results are recorded as the surface wetting tension of the test case.

[0130] Aluminum plating residue test: The surface of the test case was magnetron sputtered with aluminum. 3M 681 pressure-sensitive tape was evenly applied to the aluminum-plated surface, and the surface was placed in an oven at 40–60°C for 12 hours, then left at room temperature for 36 hours. The tape was then peeled off by hand from one end at a uniform speed, and the aluminum layer detachment and transfer were observed and recorded on a light-emitting board. A darker color indicates less light transmission on the light-emitting board, less aluminum layer detachment after peeling, and better aluminum layer adhesion.

[0131] The results of the thin film fisheye test, surface wetting tension test, and aluminum plating residue test are shown in Table 3 and Appendix. Figure 1-9 .

[0132] Table 3. Performance tests of polypropylene films prepared in Examples 7-12 and Comparative Examples 1-3

[0133]

[0134]

[0135] Visual observation of the residual aluminum coating test charts showed that the polypropylene films prepared in Examples 7-12 all exhibited excellent flatness and surface cleanliness. Table 3, comparing surface wetting tension, shows that the addition of a composite additive containing an elastomer resulted in excellent surface wetting tension and holding power for the polypropylene films. Compared to Comparative Example 1, Example 7 showed a significant improvement in aluminum layer detachment after tape peeling due to the addition of a composite additive containing both an elastomer and polyethylene. Comparing the single-layer polypropylene films of Example 7 and Comparative Example 2, the composite additive contained only high-density polyethylene. Because no composite additive containing an elastomer was added, Comparative Example 2 showed obvious defects on its film surface, while the film of Example 7 showed no significant defects, effectively solving the surface defect problem. Comparative Example 3, compared to Example 7, indicates that the poor dispersion of components in the composite additive due to the low-temperature kneading and shaping process prevented the effective components beneficial for improving the aluminum coating performance of the polypropylene film substrate from being evenly dispersed in the material. This resulted in defects on the film surface and substandard film performance. The performance comparison between the examples and comparative examples shows that the polypropylene film prepared by the composite additive and preparation method of the present invention has excellent appearance, excellent product dispersion effect, high cleanliness and low crystal point of the film surface, excellent wetting tension and long holding force of the surface-treated polypropylene film, and excellent adhesion between the film and the aluminum-plated layer.

[0136] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A composite additive for polypropylene aluminized film substrate, characterized in that, The composite additive comprises the following components: 0.1-5 parts by weight of antioxidant, 0.1-5 parts by weight of opening agent, 0.1-5 parts by weight of nucleating agent, 0.1-1 parts by weight of deacidifying agent, and 0.1-5 parts by weight of polyolefin resin; The polyolefin resin includes one or both of vinyl elastomers and propylene-based elastomers.

2. The composite additive according to claim 1, characterized in that, The polyolefin resin further includes polyethylene and / or polybutene-1; Preferably, the polyolefin resin is a mixture of polyethylene and vinyl elastomer and / or propylene elastomer, wherein the mass ratio of polyethylene to vinyl elastomer and / or propylene elastomer is 1:(0.1-5); And / or, the polyethylene is selected from one or more of linear low-density polyethylene, low-density polyethylene, and high-density polyethylene; the melt index of the polyethylene at 190°C and a load of 2.16 kg is 0.5-30 g / 10 min, and the density is 0.910-0.980 g / cm³. 3 ; And / or, the polybutene-1 has a melt index of 0.5-30 g / 10 min and a density of 0.890-0.910 g / cm³ at 190 °C and a load of 2.16 kg. 3 .

3. The composite additive according to claim 1 or 2, characterized in that, The vinyl elastomer has a melt index of 0.5-30 g / 10 min and a density of 0.80-0.90 g / cm³ at 190°C and a load of 2.16 kg. 3 ; And / or, the propylene-based elastomer has a melt index of 0.5-30 g / 10 min and a density of 0.80-0.90 g / cm³ at 230°C and a load of 2.16 kg. 3 .

4. The composite additive according to any one of claims 1-3, characterized in that, The vinyl elastomer comprises ethylene structural units and α-olefin structural units, wherein the monomers corresponding to the α-olefin structural units comprise one or more of butene, pentene, nonene, hexene, and octene, and the weight content of the α-olefin structural units in the vinyl elastomer is 20%-50%. Preferably, the vinyl elastomer is an ethylene-octene copolymer, and the content of the octene structural units is 20%-35%; And / or, the propylene-based elastomer comprises propylene structural units and one or more selected from ethylene structural units and α-olefin structural units, wherein the monomer corresponding to the α-olefin structural unit comprises one or more selected from butene, pentene, nonene, hexene and octene, and the weight content of ethylene structural units and α-olefin structural units in the propylene-based elastomer is 0.1%-20%. Preferably, the propylene-based elastomer is a propylene-ethylene copolymer, and the content of the ethylene structural unit is 0.5%-15%.

5. The composite additive according to any one of claims 1-4, characterized in that, The antioxidant is selected from one or more of phosphite antioxidants, hindered phenolic antioxidants, and hydroxylamine antioxidants; Preferably, the antioxidant is a mixture of phosphite antioxidant and hindered phenolic antioxidant, wherein the mass ratio of the phosphite antioxidant to the hindered phenolic antioxidant is 1:(0.1-10).

6. The composite additive according to any one of claims 1-5, characterized in that, The nucleating agent is selected from one or more of the following: sorbitol-based nucleating agents, organophosphate nucleating agents, rosin-based nucleating agents, hydroxy acids and their metal salts nucleating agents, and inorganic nucleating agents; Preferably, the nucleating agent is a sorbitol-based nucleating agent; more preferably, the sorbitol-based nucleating agent includes one or more of di(3,4-dimethyldibenzyl)sorbitol, dibenzyl sorbitol, and bis[2,2'-methylene-bis(4,6-di-tert-butylphenyl)phosphate]aluminum hydroxide.

7. The composite additive according to any one of claims 1-6, characterized in that, The opening agent is selected from organic or inorganic opening agents; And / or, the acid remover is selected from one or more of hydrotalcite, zinc stearate, calcium stearate, calcium hydroxide, and sodium hydroxide.

8. The method for preparing the composite additive according to any one of claims 1-7, characterized in that, Includes the following steps: Antioxidant, opening agent, nucleating agent, deacidifying agent and polyolefin resin are mixed, melt extruded at high temperature and granulated to obtain composite additive; Preferably, the high-temperature melt extrusion molding is performed using a single-screw extruder or a twin-screw extruder; And / or, the pelletizing is performed using strip-type air-cooled pelletizing or water ring pelletizing; More preferably, the single-screw extruder has a length-to-diameter ratio of 5:1-20:1 and an extrusion temperature of 80-200℃; And / or, the length-to-diameter ratio of the twin-screw extruder is 10:1-40:1, and the extrusion temperature is 80-200℃.

9. A polypropylene aluminized film substrate, characterized in that, Including the following parts by weight of raw materials: 80-99.99 parts by weight of polypropylene powder, and 0.01-20 parts by weight of the composite additive as described in any one of claims 1-7; Preferably, the polypropylene powder is selected from homopolymer polypropylene or random copolymers of propylene with ethylene and / or α-olefins; And / or, the melt flow index of the polypropylene powder at 230°C and 2.16 kg load is 1-20 g / 10 min; More preferably, the weight content of ethylene structural units and / or α-olefin structural units in the random copolymer is 0.1%-20%.

10. The method for preparing the polypropylene aluminized film substrate according to claim 9, characterized in that, Includes the following steps: After the polypropylene powder and composite additives are mixed evenly, they are extruded and pelletized by twin screw extrusion to obtain polypropylene aluminized film substrate.

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