Weather-resistant metal pearlized film and preparation method thereof

Abstract

The invention discloses a weather-resistant metal pearlized film and a preparation method thereof, and belongs to the technical field of pearlized film preparation. The weather-resistant metal pearlized film prepared by the invention sequentially comprises an upper surface layer, a pearlized layer, a metal layer and a lower surface layer from top to bottom, the weather-resistant metal pearly-luster film is prepared by the following steps: performing double-layer co-extrusion on a surface layer master batch and a pearly-luster layer master batch serving as raw materials, then performing two-way stretching to obtain an upper surface layer and a pearly-luster layer, then plating aluminum on the lower surface of the pearly-luster layer to obtain a metal layer, and finally performing an extrusion compounding process on the lower surface layer on the lower surface of the metal layer, wherein the pearlescent layer master batch comprises the following raw material components: PET, modified PET, pearlescent master batch, an antioxidant and a lubricant; the pearlescent master batch comprises the following raw material components: modified PET, a modified pearlescent pigment, a lubricant and an antioxidant. The modified PET is obtained by reacting trimethyl citrate, terephthalic acid and ethylene glycol and grafting with citric acid; the modified pearlescent pigment is obtained by modifying a mica titanium pearlescent pigment with a titanate coupling agent obtained by reacting isopropyl titanate with cysteine and lactic acid.

Description

Technical Field

[0001] The present invention relates to a weather-resistant metallic pearlescent film and a preparation method thereof. Background Art

[0002] Most of the metallic pearlescent films on the current market use polyolefin substrates such as PP (polypropylene) and PE (polyethylene). Due to the large number of C-H bonds in the molecular chains of these materials, they are very vulnerable in ultraviolet and humid and hot environments. Specifically, these materials are prone to yellowing and embrittlement. Research shows that after 2-3 years of outdoor exposure, the reflectivity of the metallic pearlescent film using PP or PE as the substrate will decrease by more than 40%, which greatly limits their use in application scenarios that require long-term stable performance. For traditional metallic pearlescent films with PP as the substrate, their tensile strength is generally lower than 30 MPa, and the puncture resistance is poor (less than 5 N / μm). Such low mechanical properties seriously limit their application potential in fields with high requirements for mechanical loads such as automotive window films and building curtain walls. Therefore, how to improve the weather resistance and mechanical properties of metallic pearlescent films has become an urgent problem to be solved in this field. Summary of the Invention

[0003] The purpose of the present invention is to provide a weather-resistant metallic pearlescent film and a preparation method thereof to solve the technical problems mentioned in the above background art.

[0004] The technical solution for achieving the purpose of the present invention is as follows:

[0005] In the first aspect, the present invention provides a weather-resistant metallic pearlescent film, which sequentially includes an upper surface layer, a pearlescent layer, a metal layer, and a lower surface layer from top to bottom; first, a surface layer masterbatch and a pearlescent layer masterbatch are used as raw materials for double-layer co-extrusion and then biaxially stretched to obtain the upper surface layer and the pearlescent layer. Subsequently, aluminizing is performed on the lower surface of the pearlescent layer to obtain the metal layer. Finally, the lower surface layer is prepared by an extrusion compounding process on the lower surface of the metal layer.

[0006] Furthermore, the raw material components of the pearlescent layer masterbatch by weight include 30-40 parts by mass of PET, 60-70 parts by mass of modified PET, 11-13 parts by mass of pearlescent masterbatch, 1-2 parts by mass of antioxidant, and 1 part by mass of lubricant; among them, the raw material components of the pearlescent masterbatch by weight include 60-90 parts by mass of modified PET, 15-25 parts by mass of modified pearlescent pigment, 0.8-1.2 parts by mass of lubricant, and 0.1-0.3 parts by mass of antioxidant.

[0007] Furthermore, the modified PET is obtained by reacting trimethyl citrate, terephthalic acid, and ethylene glycol and then grafting with citric acid.

[0008] The reaction mechanism of the modified PET is as follows:

[0009]

[0010] Further, the modified pearlescent pigment is obtained by modifying mica titania pearlescent pigment with a titanate coupling agent, wherein the titanate coupling agent is obtained by reacting isopropyl titanate with cysteine and lactic acid.

[0011] The preparation mechanism of the titanate coupling agent is as follows:

[0012]

[0013] The modification mechanism of the modified pearlescent pigment is as follows:

[0014]

[0015] In a second aspect, the present invention provides a method for preparing a weather-resistant metallic pearlescent film as described in the first aspect, comprising the following preparation steps:

[0016] (1) Preparation of the surface masterbatch: 96-98 parts by mass of PET, 1-2 parts by mass of titanium dioxide, and 1-2 parts by mass of antistatic agent are mixed at high speed for 5-15 min, and then put into a twin-screw extruder for extrusion granulation to obtain the surface masterbatch;

[0017] (2) Preparation of the pearlescent layer masterbatch: 60-70 parts by mass of modified PET, 11-13 parts by mass of pearlescent masterbatch, 1-2 parts by mass of antioxidant, and 0.5 part by mass of lubricant are mixed at high speed for 4-6 min, then 30-40 parts by mass of PET and 0.5 part by mass of lubricant are added, and the mixture is continuously stirred at high speed for 6-10 min, and then put into a twin-screw extruder for extrusion granulation to obtain the pearlescent layer masterbatch;

[0018] (3) The surface masterbatch and the pearlescent layer masterbatch are melt-extruded, cast into a sheet, longitudinally stretched, transversely stretched, heat-set, corona-treated, and sliced through a tandem screw extruder to obtain the upper surface layer and the pearlescent layer;

[0019] (4) Aluminum is plated on the lower surface of the pearlescent layer to obtain a metal layer;

[0020] (5) The film obtained in step (4) and the lower surface layer are made into a weather-resistant metallic pearlescent film through an extrusion compounding process.

[0021] Further, the preparation steps of the pearlescent masterbatch are as follows:

[0022] A1. Weigh and mix the raw materials according to the following parts by weight: 60-90 parts by mass of modified PET, 15-25 parts by mass of modified pearlescent pigment, 0.8-1.2 parts by mass of lubricant, and 0.1-0.3 part by mass of antioxidant;

[0023] A2. Put the materials weighed in step A1 into a continuous internal mixer for extrusion granulation. Among them, the temperature of the internal mixer chamber is 250 - 280 °C, the internal mixing speed is 180 - 200 rpm, the feeding speed is 12 - 14 rpm, the temperature of the extruder is 270 - 280 °C, and the main machine speed is 200 rpm.

[0024] Further, the preparation steps of the modified PET are as follows: First, heat the reaction kettle to 120 °C for preheating, then add 2.5 - 2.9 parts by mass of trimethyl citrate, 66 - 67 parts by mass of terephthalic acid, 30 - 31 parts by mass of ethylene glycol, and 2.64 - 2.68 parts by mass of the catalyst antimony glycolate into the reaction kettle, stir mechanically for 5 min to make them evenly mixed, and make a slurry. Under nitrogen protection, increase the pressure to 0.3 MPa, react at 250 - 255 °C for 1 - 1.5 h, then evacuate to a gauge pressure of -101 kPa, carry out polycondensation at 275 - 280 °C for 20 - 40 min, then continue to increase the pressure to 0.3 MPa, cool down to 260 - 265 °C, add 0.5 - 1.5 parts by mass of citric acid, and continue to react for 0.5 - 1 h to obtain the modified PET.

[0025] Using trimethyl citrate as a comonomer, feeding it into the kettle simultaneously with terephthalic acid and ethylene glycol. Utilizing the difference in reaction activity in the esterification - transesterification stage, trimethyl citrate first undergoes transesterification reaction with ethylene glycol to form a trifunctional branching center. Subsequently, terephthalic acid and ethylene glycol undergo direct esterification reaction and polycondensation. Among them, ethylene glycol is in excess and continues to grow on the branching center to form a three - armed branched - structure polyester macromolecule; reduce the polycondensation time so that a part of the hydroxyl groups are retained in the three - armed branched - structure polyester macromolecule. Then, add citric acid monomer to carry out esterification reaction with the unreacted hydroxyl groups on the three - armed branched - structure polyester macromolecule for end - capping treatment.

[0026] Further, the preparation steps of the modified pearlescent pigment are as follows: Under nitrogen protection, put 5 parts by mass of mica - titanium pearlescent pigment with a particle size of 20 - 30 μm into the reaction kettle, then add 7.5 - 8 parts by mass of ethanol, stir and disperse at 50 - 70 °C for 10 - 20 min. Subsequently, add 7.5 - 8 parts by mass of ethanol solution dissolved with 0.2 - 0.35 parts by mass of titanate coupling agent, continue to add water and stir, react at 50 - 70 °C for 1 - 2 h. After the reaction is completed, filter while it is hot, wash with ethanol, dry the filter cake at 80 °C for 24 h, and screen through a 500 - mesh sieve to obtain the modified pearlescent pigment.

[0027] Furthermore, the preparation steps of the titanate coupling agent are as follows: Under nitrogen protection, isopropyl titanate is placed in a reaction kettle, and lactic acid is added in three portions within 20 minutes under stirring conditions, cysteine is added in three portions within 20 minutes, and then the temperature is raised, and the reaction is carried out at 90-100 °C for 55-65 min. Subsequently, isopropanol is removed by vacuum distillation, and the product is discharged to obtain the titanate coupling agent. Among them, the molar ratio of isopropyl titanate, cysteine, and lactic acid is 1:1:1.

[0028] Furthermore, after the extrusion granulation in step A2, it is also necessary to perform air cooling and then put it into a hot air dryer for drying at 130-140 °C for 11-13 h for standby.

[0029] By adopting the above technical solutions, the present invention has the following beneficial effects:

[0030] The present invention discloses a weather-resistant metal pearlescent film and a preparation method thereof, belonging to the technical field of pearlescent film preparation; the weather-resistant metal pearlescent film prepared by the present invention sequentially includes an upper surface layer, a pearlescent layer, a metal layer, and a lower surface layer from top to bottom; the weather-resistant metal pearlescent film is obtained by first performing double-layer co-extrusion on a surface layer masterbatch and a pearlescent layer masterbatch and then performing biaxial stretching to obtain the upper surface layer and the pearlescent layer, then aluminizing the lower surface of the pearlescent layer to obtain the metal layer, and finally preparing the lower surface layer on the lower surface of the metal layer by an extrusion compounding process; among them, the raw material components of the pearlescent layer masterbatch include PET, modified PET, pearlescent masterbatch, antioxidant, and lubricant; the raw material components of the pearlescent masterbatch include modified PET, modified pearlescent pigment, lubricant, and antioxidant; the modified PET is obtained by grafting with citric acid after the reaction of trimethyl citrate, terephthalic acid, and ethylene glycol; the modified pearlescent pigment is obtained by modifying mica titania pearlescent pigment with a titanate coupling agent obtained by the reaction of isopropyl titanate with cysteine and lactic acid.

[0031] The present invention uses PET as the base material. Compared with PP and PE base materials, PET has high thermal stability, better mechanical properties, excellent processing performance and gloss, and the prepared weather-resistant metal pearlescent film has better mechanical properties.

[0032] The present invention modifies the pearlescent pigment with a titanate coupling agent, which can effectively increase the dispersibility of the modified pearlescent pigment in the PET base material and ensure the pearlescent effect and mechanical properties of the weather-resistant metal pearlescent film.

[0033] The modified PET of the present invention is obtained by reacting trimethyl citrate, terephthalic acid, and ethylene glycol and then grafting with citric acid to form a three-armed branched polyester macromolecule with a citric acid ester as the branching center, which increases the mechanical properties of the PET base material and forms cavities in the modified PET. Subsequently, after mixing the modified PET, modified pearlescent pigment, lubricant, and antioxidant to prepare a pearlescent masterbatch, the modified pearlescent pigment is dispersed in the modified PET through the cavities. After drying at 130-140 °C, cysteine on the modified pearlescent pigment reacts with citric acid on the modified PET to undergo dehydration condensation, forming pyridone dicarboxylic acid derivatives, enhancing the UV aging resistance of the weather-resistant metallic pearlescent film. While synergistically acting with the antioxidant to increase the weather resistance of the weather-resistant metallic pearlescent film, the modified pearlescent pigment is firmly dispersed and encapsulated in the modified PET, effectively solving the problem of poor encapsulation of the pearlescent pigment by PET, and further ensuring the mechanical properties and pearlescent effect of the weather-resistant metallic pearlescent film. Detailed implementation manners

[0034] To better understand the above technical solution, the above technical solution will be described in detail below in combination with specific implementation manners.

[0035] Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0036] The following embodiments are only used to more clearly illustrate the technical solution of the present invention and cannot be used to limit the protection scope of the present invention.

[0037] Some raw materials of the embodiments and comparative examples of the present invention are as follows:

[0038] Antistatic agent: Antistatic agent JK-23;

[0039] PET: Melting point 257 °C, intrinsic viscosity 0.62 dl / g;

[0040] The antioxidant used is antioxidant 1010;

[0041] The lubricant used is EBS wax;

[0042] The lower surface layer uses a 12-μm-thick PET film;

[0043] The average particle size of titanium dioxide is 150 nm.

[0044] (Example 1)

[0045] A preparation method of a weather-resistant metallic pearlescent film includes the following preparation steps:

[0046] (1) Preparation of surface masterbatch: Mix 96 parts by mass of PET, 2 parts by mass of titanium dioxide, and 2 parts by mass of antistatic agent at a high speed for 5 min, and then put them into a twin-screw extruder for extrusion granulation to obtain the surface masterbatch; among them, the high-speed mixing speed is 700 rpm, the screw diameter D of the twin-screw extruder is 62 mm, the length-diameter ratio L / D is 48, the main engine speed is 490 Hz, and the barrel temperature control settings are as follows: zone 1 is 220 °C, zone 2 is 240 °C, zones 3-11 are 280 °C, and the die head temperature is 280 °C;

[0047] (2) Preparation of pearlescent layer masterbatch: Mix 60 parts by mass of modified PET, 11 parts by mass of pearlescent masterbatch, 1 part by mass of antioxidant, and 0.5 part by mass of lubricant at a high speed for 4 min, then add 30 parts by mass of PET and 0.5 part by mass of lubricant, continue to stir at a high speed for 6 min, and then put them into a twin-screw extruder for extrusion granulation to obtain the pearlescent layer masterbatch; among them, the high-speed mixing speed is 1000 rpm, the screw diameter D of the twin-screw extruder is 62 mm, the length-diameter ratio L / D is 48, the main engine speed is 490 Hz, and the barrel temperature control settings are as follows: zone 1 is 220 °C, zone 2 is 240 °C, zones 3-11 are 270 °C, and the die head temperature is 270 °C;

[0048] (3) Melt-extrude the surface masterbatch and the pearlescent layer masterbatch through a series-connected screw extruder, cast into a sheet, longitudinally stretch, transversely stretch, heat-set, corona-treat, and slice to obtain an upper surface layer with a thickness of 12 μm and a pearlescent layer with a thickness of 18 μm; in the preheating process of the longitudinal stretching process, the preheating temperature is about 95 °C; the temperature in the stretching process is 120 °C; the stretching ratio is 3.5; after longitudinal stretching, it is rapidly cooled at a temperature below 35 °C; in the transverse stretching process, the preheating temperature is 95 °C; the stretching temperature is 96 °C; the stretching ratio is 3.5; the heat-setting temperature is 225 °C.

[0049] (4) Aluminum is plated on the lower surface of the pearlescent layer to obtain a metal layer with a thickness of 20 nm;

[0050] (5) The film obtained in step (4) and the lower surface layer with a thickness of 12 μm are made into a weather-resistant metal pearlescent film through an extrusion lamination process, where the doctor blade pressure of the extrusion lamination process is 0.3 Mpa, the adhesive pressure is 0.3 Mpa, and the laminating pressure is 0.4 Mpa.

[0051] The preparation steps of the pearlescent masterbatch are as follows:

[0052] A1. Weigh and mix the raw materials according to the following parts by weight: 60 parts by mass of modified PET, 15 parts by mass of modified pearlescent pigment, 0.8 part by mass of lubricant, and 0.1 part by mass of antioxidant;

[0053] A2. Put the materials weighed in step A1 into a continuous internal mixer for extrusion granulation. After extrusion and pelletization, air cooling is required, and then it is dried in a hot air dryer at 130°C for 11 hours for standby. Among them, the temperature of the internal mixer is 250°C, the internal mixing speed is 180 rpm, the feeding speed is 12 rpm, the temperature of the extruder is 270°C, and the main machine speed is 200 rpm.

[0054] The preparation steps of the modified PET are as follows: First, heat the reaction kettle to 120°C for preheating, then add 2.5 parts by mass of trimethyl citrate, 66 parts by mass of terephthalic acid, 30 parts by mass of ethylene glycol, and 2.64 parts by mass of the catalyst antimony glycolate to the reaction kettle, and mechanically stir for 5 minutes to make them evenly mixed into a slurry. Under nitrogen protection, increase the pressure to 0.3 MPa, react at 250°C for 1 hour, then evacuate to a gauge pressure of -101 kPa, and carry out polycondensation at 275°C for 20 minutes. Then continue to increase the pressure to 0.3 MPa, cool down to 260°C, add 0.5 parts by mass of citric acid, and continue to react for 0.5 hour to obtain modified PET.

[0055] The preparation steps of the modified pearlescent pigment are as follows: Under nitrogen protection, place 5 parts by mass of mica titania pearlescent pigment with an average particle size of 20 μm in a reaction kettle, then add 7.5 parts by mass of ethanol, stir and disperse at 50°C for 10 minutes, and then add 7.5 parts by mass of ethanol solution dissolved with 0.2 parts by mass of titanate coupling agent, continue to add water and stir, react at 50°C for 1 hour. After the reaction, filter while it is hot, wash with ethanol, dry the filter cake at 80°C for 24 hours, and pass through a 500-mesh sieve to obtain the modified pearlescent pigment.

[0056] The preparation steps of the titanate coupling agent are as follows: Under nitrogen protection, put isopropyl titanate into a reaction kettle, add lactic acid in 3 portions within 20 minutes under stirring conditions, add cysteine in three portions within 20 minutes, then raise the temperature, and react at 90°C for 55 minutes. Then remove isopropanol by vacuum distillation and discharge to obtain the titanate coupling agent. Among them, the molar ratio of isopropyl titanate, cysteine, and lactic acid is 1:1:1.

[0057] (Example 2)

[0058] A method for preparing a weather-resistant metal pearlescent film includes the following preparation steps:

[0059] (1) Preparation of the surface masterbatch: Mix 97 parts by mass of PET, 1.5 parts by mass of titanium dioxide, and 1.5 parts by mass of antistatic agent at a high speed for 10 min, and then put them into a twin-screw extruder for extrusion granulation to obtain the surface masterbatch; among them, the high-speed mixing speed is 700 rpm, the screw diameter D of the twin-screw extruder is 62 mm, the length-diameter ratio L / D is 48, the main engine speed is 490 Hz, and the barrel temperature control settings are as follows: zone 1 is 220 °C, zone 2 is 240 °C, zones 3 - 11 are 280 °C, and the die head temperature is 280 °C;

[0060] (2) Preparation of the pearlescent layer masterbatch: Mix 65 parts by mass of modified PET, 12 parts by mass of pearlescent masterbatch, 1.5 parts by mass of antioxidant, and 0.5 parts by mass of lubricant at a high speed for 5 min, then add 35 parts by mass of PET and 0.5 parts by mass of lubricant, continue to stir at a high speed for 8 min, and then put them into a twin-screw extruder for extrusion granulation to obtain the pearlescent layer masterbatch; among them, the high-speed mixing speed is 1000 rpm, the screw diameter D of the twin-screw extruder is 62 mm, the length-diameter ratio L / D is 48, the main engine speed is 490 Hz, and the barrel temperature control settings are as follows: zone 1 is 220 °C, zone 2 is 240 °C, zones 3 - 11 are 270 °C, and the die head temperature is 270 °C;

[0061] (3) Melt extrude the surface masterbatch and the pearlescent layer masterbatch through a series-connected screw extruder, cast into a sheet, longitudinally stretch, transversely stretch, heat-set, corona-treat, and slice to obtain an upper surface layer with a thickness of 12 μm and a pearlescent layer with a thickness of 18 μm; in the preheating process of the longitudinal stretching process, the preheating temperature is about 95 °C; the temperature in the stretching process is 120 °C; the stretching ratio is 3.5; after longitudinal stretching, it is quenched suddenly at a temperature below 35 °C; in the transverse stretching process, the preheating temperature is 95 °C; the stretching temperature is 96 °C; the stretching ratio is 3.5; the heat-setting temperature is 225 °C.

[0062] (4) Deposit aluminum on the lower surface of the pearlescent layer to obtain a metal layer with a thickness of 20 nm;

[0063] (5) Use the film obtained in step (4) and a 12-μm-thick lower surface layer to produce a weather-resistant metal pearlescent film through an extrusion lamination process, where the doctor blade pressure in the extrusion lamination process is 0.3 Mpa, the adhesive pressure is 0.3 Mpa, and the laminating pressure is 0.4 Mpa.

[0064] The preparation steps of the pearlescent masterbatch are as follows:

[0065] A1. Weigh and mix the raw materials according to the following parts by weight: 75 parts by mass of modified PET, 20 parts by mass of modified pearlescent pigment, 1 part by mass of lubricant, and 0.2 part by mass of antioxidant;

[0066] A2. Put the weighed materials in step A1 into a continuous internal mixer for extrusion granulation. After extrusion and pelletization, air cooling is required, and then it is put into a blast dryer and dried at 135°C for 12 hours for standby; among them, the temperature of the internal mixer is 265°C, the internal mixing speed is 190 rpm, the feeding speed is 13 rpm, the temperature of the extruder is 275°C, and the main machine speed is 200 rpm.

[0067] The preparation steps of the modified PET are as follows: First, heat the reaction kettle to 120°C for preheating, then add 2.7 parts by mass of trimethyl citrate, 66.6 parts by mass of terephthalic acid, 30.7 parts by mass of ethylene glycol, and 2.66 parts by mass of the catalyst antimony glycolate into the reaction kettle, and mechanically stir for 5 minutes to make them evenly mixed, and make a slurry. Under nitrogen protection, increase the pressure to 0.3 MPa, react at 253°C for 1.3 hours, then evacuate to a gauge pressure of -101 kPa, carry out polycondensation at 278°C for 30 minutes, then continue to increase the pressure to 0.3 MPa, cool down to 263°C, add 1 part by mass of citric acid, and continue to react for 0.8 hours to obtain modified PET.

[0068] The preparation steps of the modified pearlescent pigment are as follows: Under nitrogen protection, put 5 parts by mass of mica titanium pearlescent pigment with an average particle size of 20 μm into the reaction kettle, then add 7.8 parts by mass of ethanol, stir and disperse at 60°C for 15 minutes, then add 7.8 parts by mass of ethanol solution dissolved with 0.3 parts by mass of titanate coupling agent, continue to add water and stir, react at 60°C for 1.5 hours. After the reaction is completed, filter while it is hot, wash with ethanol, dry the filter cake at 80°C for 24 hours, and pass through a 500-mesh sieve to obtain the modified pearlescent pigment.

[0069] The preparation steps of the titanate coupling agent are as follows: Under nitrogen protection, put isopropyl titanate into the reaction kettle, add lactic acid in 3 portions within 20 minutes under stirring conditions, add cysteine in three portions within 20 minutes, then raise the temperature, react at 95°C for 60 minutes, then carry out vacuum distillation to remove isopropanol, and discharge to obtain the titanate coupling agent, where the molar ratio of isopropyl titanate, cysteine, and lactic acid is 1:1:1.

[0070] (Example 3)

[0071] A preparation method of a weather-resistant metal pearlescent film includes the following preparation steps:

[0072] (1) Preparation of the surface masterbatch: Mix 98 parts by mass of PET, 1 part by mass of titanium dioxide, and 1 part by mass of antistatic agent at a high speed for 15 min, and then put them into a twin-screw extruder for extrusion granulation to obtain the surface masterbatch. Among them, the high-speed mixing speed is 700 rpm, the screw diameter D of the twin-screw extruder is 62 mm, the length-diameter ratio L / D is 48, the main machine speed is 490 Hz, and the barrel temperature control settings are as follows: zone 1 is 220 °C, zone 2 is 240 °C, zones 3 - 11 are 280 °C, and the die head temperature is 280 °C;

[0073] (2) Preparation of the pearlescent layer masterbatch: Mix 70 parts by mass of modified PET, 13 parts by mass of pearlescent masterbatch, 2 parts by mass of antioxidant, and 0.5 part by mass of lubricant at a high speed for 6 min, then add 40 parts by mass of PET and 0.5 part by mass of lubricant, and continue to stir at a high speed for 10 min, and then put them into a twin-screw extruder for extrusion granulation to obtain the pearlescent layer masterbatch. Among them, the high-speed mixing speed is 1000 rpm, the screw diameter D of the twin-screw extruder is 62 mm, the length-diameter ratio L / D is 48, the main machine speed is 490 Hz, and the barrel temperature control settings are as follows: zone 1 is 220 °C, zone 2 is 240 °C, zones 3 - 11 are 270 °C, and the die head temperature is 270 °C;

[0074] (3) Melt-extrude, cast sheet, longitudinally stretch, transversely stretch, heat-set, corona-treat, and slice the surface masterbatch and the pearlescent layer masterbatch through a series-connected screw extruder to obtain an upper surface layer with a thickness of 12 μm and a pearlescent layer with a thickness of 18 μm. In the preheating process of the longitudinal stretching process, the preheating temperature is about 95 °C; the temperature of the stretching process is 120 °C; the stretching ratio is 3.5; after longitudinal stretching, it is rapidly cooled at a temperature lower than 35 °C; in the transverse stretching process, the preheating temperature is 95 °C; the stretching temperature is 96 °C; the stretching ratio is 3.5; the heat-setting temperature is 225 °C.

[0075] (4) Aluminum is plated on the lower surface of the pearlescent layer to obtain a metal layer with a thickness of 20 nm;

[0076] (5) The film obtained in step (4) and a lower surface layer with a thickness of 12 μm are made into a weather-resistant metal pearlescent film through an extrusion compounding process. Among them, the doctor blade pressure of the extrusion compounding process is 0.3 Mpa, the adhesive pressure is 0.3 Mpa, and the lamination pressure is 0.4 Mpa.

[0077] The preparation steps of the pearlescent masterbatch are as follows:

[0078] A1. Weigh and proportion the raw materials according to the following parts by weight: 90 parts by mass of modified PET, 25 parts by mass of modified pearlescent pigment, 1.2 parts by mass of lubricant, and 0.3 part by mass of antioxidant;

[0079] A2. Put the materials weighed in step A1 into a continuous internal mixer for extrusion granulation. After extrusion and pelletization, air cooling is required, and then it is put into a blast dryer for drying at 140 °C for 13 h for standby; among them, the temperature of the internal mixer is 280 °C, the internal mixing speed is 200 rpm, the feeding speed is 14 rpm, the temperature of the extruder is 280 °C, and the main engine speed is 200 rpm.

[0080] The preparation steps of the modified PET are as follows: First, heat the reaction kettle to 120 °C for preheating, then add 2.9 parts by mass of trimethyl citrate, 67 parts by mass of terephthalic acid, 31 parts by mass of ethylene glycol, and 2.68 parts by mass of the catalyst antimony glycolate into the reaction kettle, and mechanically stir for 5 min to make them evenly mixed, and make a slurry. Under nitrogen protection, increase the pressure to 0.3 MPa, react at 255 °C for 1.5 h, then evacuate to a gauge pressure of -101 kPa, carry out polycondensation at 280 °C for 40 min, then continue to increase the pressure to 0.3 MPa, cool down to 265 °C, add 1.5 parts by mass of citric acid, and continue to react for 1 h to obtain modified PET.

[0081] The preparation steps of the modified pearlescent pigment are as follows: Under nitrogen protection, put 5 parts by mass of 30-μm mica titanium pearlescent pigment into the reaction kettle, then add 8 parts by mass of ethanol, stir and disperse at 70 °C for 20 min, then add 8 parts by mass of ethanol solution dissolved with 0.35 parts by mass of titanate coupling agent, continue to add water and stir, react at 70 °C for 2 h. After the reaction is completed, filter while it is hot, wash with ethanol, dry the filter cake at 80 °C for 24 h, and screen through a 500-mesh sieve to obtain the modified pearlescent pigment.

[0082] The preparation steps of the titanate coupling agent are as follows: Under nitrogen protection, put isopropyl titanate into the reaction kettle, add lactic acid in 3 portions within 20 minutes under stirring conditions, add cysteine in three portions within 20 minutes, then raise the temperature and react at 100 °C for 65 min, then remove isopropanol by vacuum distillation, and discharge to obtain the titanate coupling agent, where the molar ratio of isopropyl titanate, cysteine, and lactic acid is 1:1:1.

[0083] (Comparative Example 1)

[0084] The difference between Comparative Example 1 and Example 2 is that the raw material components of the pearlescent masterbatch by weight include 100 parts by mass of PET, 12 parts by mass of pearlescent masterbatch, 2 parts by mass of antioxidant, and 1 part by mass of lubricant; among them, the raw material components of the pearlescent masterbatch by weight include 75 parts by mass of PET, 20 parts by mass of modified pearlescent pigment, 1 part by mass of lubricant, and 0.2 part by mass of antioxidant. The remaining steps and components are the same as those in Example 2.

[0085] (Comparative Example 2)

[0086] The difference between Comparative Example 2 and Example 2 is that the pearlescent masterbatch is made of mica titania pearlescent pigment, and the remaining steps and components are the same as those in Example 2.

[0087] (Comparative Example 3)

[0088] The difference between Comparative Example 3 and Example 2 is that the modified pearlescent pigment is made of mica titania pearlescent pigment modified with isopropyltris(dioctylpyrophosphato)titanate, and the remaining steps and components are the same as those in Example 2.

[0089] (Comparative Example 4)

[0090] The difference between Comparative Example 4 and Example 2 lies in Step A2. The Step A2 of Comparative Example 4 is as follows: Put the weighed materials in Step A1 into a continuous internal mixer for extrusion granulation. After extrusion and pelletizing, air cooling is also required, and it is reserved for use; the remaining steps and components are the same as those in Example 2.

[0091] Effect Example

[0092] Tensile strength test: Refer to GB / T 1040.3 to test the tensile properties of the weather-resistant metallic pearlescent films prepared in the examples and comparative examples.

[0093] UV resistance test: Use an ultraviolet accelerated aging test chamber to simulate the aging process of the weather-resistant metallic pearlescent films prepared in the examples and comparative examples in nature. The environmental temperature is set at 50 °C, the peak wavelength of ultraviolet radiation is 313 nm, and the power of the ultraviolet fluorescent lamp tube is 0.06 kW. After irradiating for 720 h, test the 60° gloss before and after ultraviolet aging. The retention rate of 60° gloss after ultraviolet aging = 100% * (60° gloss before ultraviolet aging - 60° gloss after ultraviolet aging) / 60° gloss before ultraviolet aging.

[0094] The following Table 1 shows the performance test results of the weather-resistant metallic pearlescent films prepared in Examples 1 to 3 and Comparative Examples 1 to 4:

[0095] Table 1

[0096]

[0097]

[0098] It can be seen from Table 1 above that the weather-resistant metallic pearlescent films prepared in Examples 1 to 3 have good appearance, mechanical properties and UV resistance.

[0099] The difference between Comparative Example 1 and Example 2 is that all of the pearlescent layer masterbatch uses ordinary PET. Compared with Comparative Example 1, the weather-resistant metallic pearlescent film prepared in Example 2 has better appearance, mechanical properties and UV resistance.

[0100] The difference between Comparative Example 2 and Example 2 lies in that the pearlescent masterbatch uses unmodified pearlescent pigments. Compared with Comparative Example 2, the weather-resistant metallic pearlescent film prepared in Example 2 has better appearance, mechanical properties and UV resistance.

[0101] The difference between Comparative Example 3 and Example 2 lies in that a commercial titanate coupling agent, isopropyl tris(dioctylpyrophosphate acyl oxy) titanate, is used to modify the pearlescent pigment instead of the self-made titanate coupling agent. Compared with Comparative Example 3, the weather-resistant metallic pearlescent film prepared in Example 2 has better appearance, mechanical properties and UV resistance.

[0102] The difference between Comparative Example 4 and Example 2 lies in that the pearlescent masterbatch is not dried after granulation. Compared with Comparative Example 4, the weather-resistant metallic pearlescent film prepared in Example 2 has better UV resistance.

[0103] It can be seen from the comparison between Example 2 and Comparative Examples 1-4 that the modified PET and the pearlescent pigment modified with the self-made titanate coupling agent of the present invention have a synergistic effect, significantly improving the appearance mechanical properties and UV aging resistance of the weather-resistant metallic pearlescent film; it can be seen from the comparison between Comparative Examples 2-34 and Example 2 that ordinary PET, ordinary modified pearlescent pigments or unmodified pearlescent pigments result in insufficient interfacial bonding force, and the tensile strength and weather resistance are greatly reduced.

[0104] The specific embodiments described above further elaborate on the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A weather-resistant metallic pearlescent film, characterized in that: It includes, from top to bottom, an upper surface layer, a pearlescent layer, a metal layer, and a lower surface layer; firstly, a surface layer masterbatch and a pearlescent layer masterbatch are used as raw materials for double-layer co-extrusion and then biaxially stretched to obtain an upper surface layer and a pearlescent layer, then aluminum is plated on the lower surface of the pearlescent layer to obtain a metal layer, and finally the lower surface layer is obtained by an extrusion composite process on the lower surface of the metal layer.

2. The weather-resistant metallic pearlescent film according to claim 1, characterized in that: The raw material components of the pearlescent layer masterbatch include 30-40 parts by weight of PET, 60-70 parts by weight of modified PET, 11-13 parts by weight of pearlescent masterbatch, 1-2 parts by weight of antioxidant, and 1 part by weight of lubricant; wherein, the raw material components of the pearlescent masterbatch include 60-90 parts by weight of modified PET, 15-25 parts by weight of modified pearlescent pigment, 0.8-1.2 parts by weight of lubricant, and 0.1-0.3 parts by weight of antioxidant.

3. The weather-resistant metallic pearlescent film according to claim 2, characterized in that: Modified PET is obtained by reacting trimethyl citrate, terephthalic acid, and ethylene glycol and then grafting with citric acid.

4. The weather-resistant metallic pearlescent film according to claim 2, characterized in that: The modified pearlescent pigment is obtained by modifying mica titanium pearlescent pigment with a titanate coupling agent, wherein the titanate coupling agent is obtained by reacting isopropyl titanate with cysteine ​​and lactic acid.

5. A method for preparing a weather-resistant metallic pearlescent film according to any one of claims 1 to 4, characterized in that: The method comprises the following preparation steps: (1) Preparation of surface masterbatch: 96-98 parts by weight of PET, 1-2 parts by weight of titanium dioxide, and 1-2 parts by weight of antistatic agent are mixed at high speed for 5-15 minutes, and then put into a twin-screw extruder for extrusion and granulation to obtain a surface masterbatch; (2) Preparation of pearlescent layer masterbatch: 60-70 parts by weight of modified PET, 11-13 parts by weight of pearlescent masterbatch, 1-2 parts by weight of antioxidant, and 0.5 parts by weight of lubricant are mixed at high speed for 4-6 minutes, and then 30-40 parts by weight of PET and 0.5 parts by weight of lubricant are added, and high-speed stirring is continued for 6-10 minutes, and then the mixture is put into a twin-screw extruder for extrusion and granulation to obtain a pearlescent layer masterbatch; (3) melt-extruding the surface masterbatch and the pearlescent layer masterbatch through a tandem screw extruder, casting, longitudinal stretching, transverse stretching, heat setting, corona treatment, and slicing to obtain an upper surface layer and a pearlescent layer; (4) aluminum is plated on the lower surface of the pearlescent layer to obtain a metal layer; (5) The film obtained in step (4) is combined with the lower surface layer through an extrusion composite process to obtain a weather-resistant metallic pearlescent film.

6. The method for preparing the weather-resistant metallic pearlescent film according to claim 5, characterized in that: The preparation steps of the pearlescent masterbatch are as follows: A1. Weigh the following raw materials in parts by weight: 60 to 90 parts by weight of modified PET, 15 to 25 parts by weight of modified pearlescent pigment, 0.8 to 1.2 parts by weight of lubricant, and 0.1 to 0.3 parts by weight of antioxidant; A2. The weighed material in step A1 is placed in a continuous internal mixer for extrusion granulation, wherein the temperature of the internal mixer chamber is 250-280°C, the internal mixer speed is 180-200rpm, the feeding speed is 12-14rpm, the extruder temperature is 270-280°C, and the main engine speed is 200rpm.

7. The method for preparing the weather-resistant metallic pearlescent film according to claim 6, characterized in that: The preparation steps of the modified PET are as follows: first, a reaction kettle is heated to 120° C. for preheating, and then 2.5 to 2.9 parts by mass of trimethyl citrate, 66 to 67 parts by mass of terephthalic acid, 30 to 31 parts by mass of ethylene glycol and 2.64 to 2.68 parts by mass of catalyst antimony glycol are added into the reaction kettle and mechanically stirred for 5 minutes to make them evenly mixed, and slurry is formed, and the pressure is increased to 0.3 MPa under nitrogen protection, and the mixture is reacted at 250 to 255° C. for 1 to 1.5 hours, and then the mixture is evacuated to a gauge pressure of -101 kPa, and polycondensed at 275 to 280° C. for 20 to 40 minutes, and then the pressure is continuously increased to 0.3 MPa, and the temperature is reduced to 260 to 265° C., and 0.5 to 1.5 parts by mass of citric acid are added, and the mixture is reacted for 0.5 to 1 hour to obtain the modified PET.

8. The method for preparing the weather-resistant metallic pearlescent film according to claim 6, characterized in that: The preparation steps of the modified pearlescent pigment are as follows: under nitrogen protection, 5 parts by weight of mica titanium pearlescent pigment with a size of 20 to 30 μm are placed in a reaction kettle, followed by adding 7.5 to 8 parts by weight of ethanol, stirring and dispersing at 50 to 70° C. for 10 to 20 minutes, then adding 7.5 to 8 parts by weight of an ethanol solution containing 0.2 to 0.35 parts by weight of a titanate coupling agent, continuing to add water and stirring, reacting at 50 to 70° C. for 1 to 2 hours, filtering while hot after the reaction is completed, washing with ethanol, drying the filter cake at 80° C. for 24 hours, and passing through a 500-mesh sieve to obtain the modified pearlescent pigment.

9. The method for preparing a weather-resistant metallic pearlescent film according to claim 8, characterized in that: The preparation steps of the titanate coupling agent are as follows: under nitrogen protection, isopropyl titanate is placed in a reaction kettle, lactic acid is added three times within 20 minutes, cysteine ​​is added three times within 20 minutes under stirring conditions, then the temperature is raised, and the reaction is carried out at 90-100° C. for 55-65 minutes, and then the isopropyl alcohol is removed by reduced pressure distillation, and the material is discharged to obtain the titanate coupling agent, wherein the molar ratio of isopropyl titanate, cysteine ​​and lactic acid is 1:1:

1.

10. The method for preparing the weather-resistant metallic pearlescent film according to claim 6, characterized in that: After the extrusion and pelletizing in step A2, the pellets need to be air-cooled and then placed in a blast dryer at 130-140° C. for 11-13 hours for standby use.

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