A coated matte PET film and preparation method thereof

Abstract

The invention discloses a coating type matte PET film and a preparation method thereof, belonging to the technical field of films. The preparation method comprises the following steps: preparing an antistatic agent, preparing a matting agent, preparing a coating liquid, and coating; in the preparation of the coating liquid, an aqueous polyurethane dispersion, an antistatic agent, a matting agent, and an aqueous silicone defoamer are mixed, stirred at room temperature, an acrylic leveling agent, an anti-wear agent, and 3-aminopropyltrimethoxysilane are added, the stirring is continued, polycarbodiimide is added, the stirring is continued, and the coating liquid is obtained; the coating type matte PET film prepared by the invention has high haze, good appearance, no fisheyes and shrinkage cavities on the surface, uniform haze, strong coating adhesion, short preparation time, and strong water resistance.

Description

Technical Field

[0001] The invention relates to the technical field of films, and in particular to a coated matte PET film and a preparation method thereof. Background Art

[0002] PET film, also known as polyester film, has good transparency, air tightness and mechanical properties. Its toughness is the best among all thermoplastic films. It has moderate moisture resistance, high gloss, and good heat resistance, cold resistance, oil resistance, chemical stability and dimensional stability. It is widely used in magnetic recording, photosensitive materials, electronics, printing, electrical insulation, packaging decoration, screen protection and other fields.

[0003] For some products in the fields of electronics, printing, screen protection, etc., the plastic film used is required to have a certain matte degree, such as the film buttons in the electronic field and the paper coating in the printing field, which require the use of matte PET film. The commonly used method for preparing matte PET film is to use a coating liquid on the PET film for coating. The commonly used coating liquid is an aqueous polyurethane dispersion. When preparing the matte PET film, the aqueous polyurethane dispersion is added to the surface of the PET film by coating to prepare a coated matte PET film. The aqueous polyurethane dispersion has a self-extinction effect, specifically the aqueous polyurethane dispersion can form polyurethane particles with different particle sizes on the surface of the PET film after drying. The polyurethane particles form a rough surface on the surface of the PET film, and the matte effect is achieved by scattering light. However, the haze of the coated matte PET film prepared by the above method can only reach 20% at most, and due to the poor antistatic property of the PET film, the aqueous polyurethane dispersion will also cause uneven coating during coating, further resulting in the presence of fish eyes and shrinkage holes on the surface of the prepared coated matte PET film, and uneven haze.

[0004] In view of the above problems, the commonly used solutions are as follows: first, adding matting powder to the aqueous polyurethane dispersion. The matting agent mainly includes metal soap matting agent, wax matting agent, and inorganic filler matting agent. Among them, the metal soap matting agent is mainly suspended on the surface of the coated matte PET film in the form of fine particles after the aqueous polyurethane dispersion is dried due to its incompatibility with the polyurethane in the aqueous polyurethane dispersion, thereby improving the roughness of the coated matte PET film and further improving the haze of the coated matte PET film; the wax matting agent can be suspended on the surface of the coated matte PET film in the form of fine crystals after the aqueous polyurethane dispersion is dried, thereby improving the roughness of the coated matte PET film and further improving the haze of the coated matte PET film. The haze of the PET film; the inorganic filler matting agent is also mainly suspended on the surface of the coated matte PET film in the form of fine particles through the incompatibility with the polyurethane in the aqueous polyurethane dispersion after the aqueous polyurethane dispersion is dried, thereby increasing the roughness of the coated matte PET film and further increasing the haze of the coated matte PET film; second, antistatic agents or conductive particles are added to the aqueous polyurethane dispersion. The antistatic agents mainly include permanent antistatic agents and non-permanent antistatic agents, among which non-permanent antistatic agents include cationic antistatic agents, anionic antistatic agents, zwitterionic antistatic agents, and non-ionic antistatic agents. The conductive particles mainly include carbon nanotubes, metal nanoparticles, and metal oxide nanoparticles.

[0005] However, when preparing the coated matte PET film according to the above solution, the following problems exist: first, in order to improve the haze of the prepared coated matte PET film, it is necessary to increase the amount of matting agent, but the excessive amount of metal soap matting agent and inorganic filler matting agent will affect the leveling property of the aqueous polyurethane dispersion and the adhesion to the PET film, further resulting in uneven haze distribution of the prepared coated matte PET film and poor coating adhesion; second, the excessive amount of wax matting agent will cause the prepared coated matte PET film to have a poor adhesion; A dense film is formed on the surface of the matte PET film, which slows down the drying speed of the aqueous polyurethane dispersion, further leading to a long preparation time for the coated matte PET film; thirdly, the permanent antistatic agent in the antistatic agent is generally a colored high molecular polymer, which will affect the appearance of the coated matte PET film; fourthly, the non-permanent antistatic agent in the antistatic agent has strong hygroscopicity, which leads to strong hygroscopicity of the prepared coated matte PET film, further leading to poor water resistance of the prepared coated matte PET film. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides a coated matte PET film and a preparation method thereof. The prepared coated matte PET film has high haze, good appearance, no fisheyes and shrinkage holes on the surface, uniform haze, strong coating adhesion, short preparation time and strong water resistance.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing a coated matte PET film, comprising the following steps: preparing an antistatic agent, preparing a matting agent, preparing a coating liquid, and coating;

[0009] The preparation of the antistatic agent comprises mixing white carbon black and a sodium chloride aqueous solution, stirring the mixture at a stirring speed of 300-400 rpm for 2-2.5 hours at room temperature, centrifuging the mixture at a centrifugal speed of 11000-12000 rpm for 14-16 minutes, taking a precipitate, washing the mixture with deionized water, drying the mixture, mixing the mixture with a polydiallyldimethylammonium chloride aqueous solution, stirring the mixture at a stirring speed of 300-400 rpm for 2-2.5 hours at room temperature, centrifuging the mixture at a centrifugal speed of 11000-12000 rpm for 14-16 minutes, taking a precipitate, washing the mixture with deionized water, and drying the mixture. After washing, drying, mixing with a calcium chloride aqueous solution, stirring at a stirring speed of 300-400 rpm for 1-1.5 hours at room temperature, centrifuging at a centrifugal speed of 11000-12000 rpm for 14-16 minutes, taking a precipitate, washing with deionized water, drying, mixing with a carboxymethyl cellulose aqueous solution, stirring at a stirring speed of 300-400 rpm for 1-1.5 hours at room temperature, centrifuging at a centrifugal speed of 11000-12000 rpm for 14-16 minutes, taking a precipitate, washing with deionized water, and drying to obtain an antistatic agent;

[0010] In the preparation of the antistatic agent, the mass volume ratio of white carbon black, sodium chloride aqueous solution, polydiallyldimethylammonium chloride aqueous solution, calcium chloride aqueous solution, and carboxymethyl cellulose aqueous solution is 200g:1700-2000mL:1700-2000mL:1600-1800mL:2400-2600mL;

[0011] The average particle size of the white carbon black is 30 nm;

[0012] The mass concentration of the sodium chloride aqueous solution is 5%;

[0013] The mass concentration of the polydiallyldimethylammonium chloride aqueous solution is 1%;

[0014] The mass concentration of the calcium chloride aqueous solution is 5%;

[0015] The mass concentration of the carboxymethyl cellulose aqueous solution is 2%;

[0016] The matting agent is prepared by mixing talcum powder and sodium stearate aqueous solution, stirring at a stirring speed of 300-400rpm for 2-2.5h at 80-85°C, centrifuging at a centrifugal speed of 4000-5000rpm for 5-6min, taking a precipitate, washing it with deionized water, drying it, and then mixing it with a calcium chloride aqueous solution, stirring at a stirring speed of 300-400rpm for 1.5-2h at room temperature, centrifuging at a centrifugal speed of 4000-5000rpm for 5-6min, taking a precipitate, washing it with deionized water, drying it, and then mixing it with anhydrous stearyl alcohol solution, stirring at a stirring speed of 300-400rpm for 2-2.5h at room temperature, centrifuging at a centrifugal speed of 4000-5000rpm for 5-6min, taking a precipitate, washing it with anhydrous ethanol, and drying it to obtain a matting agent;

[0017] In the preparation of the matting agent, the mass volume ratio of talc, sodium stearate aqueous solution, calcium chloride aqueous solution, and stearyl alcohol anhydrous ethanol solution is 200g:1200-1300mL:1300-1500mL:1300-1500mL;

[0018] The mass concentration of the sodium stearate aqueous solution is 1%;

[0019] The average particle size of the talc is 10 μm;

[0020] The mass concentration of the calcium chloride aqueous solution is 5%;

[0021] The mass concentration of the stearyl alcohol anhydrous ethanol solution is 1%;

[0022] The coating liquid is prepared by mixing an aqueous polyurethane dispersion, an antistatic agent, a matting agent, and an aqueous silicone defoamer, stirring the mixture at a stirring speed of 900-1000 rpm for 30-40 minutes at room temperature, adding an acrylic leveling agent, an anti-wear agent, and 3-aminopropyltrimethoxysilane, and continuing to stir for 10-12 minutes, adding polycarbodiimide, and continuing to stir for 4-5 minutes to obtain a coating liquid;

[0023] In the coating liquid, the mass ratio of the aqueous polyurethane dispersion, the antistatic agent, the matting agent, the aqueous silicone defoaming agent, the acrylic leveling agent, the wear-resistant agent, the 3-aminopropyltrimethoxysilane, and the polycarbodiimide is 100:4-4.5:4-6.5:0.3-0.4:2.4-2.7:2-2.3:2.5-3:1.3-1.4;

[0024] The aqueous polyurethane dispersion is a polycarbonate-type aqueous polyurethane dispersion, and the solid content is 35% by mass;

[0025] The model of the wear-resistant agent is CUBD-NM01;

[0026] The coating comprises: placing the pre-crystallized and dried A-layer polyester resin slice, the pre-crystallized and dried B-layer polyester resin slice, and the pre-crystallized and dried C-layer polyester resin slice into a No. 1 twin-screw extruder, a single-screw extruder, and a No. 2 twin-screw extruder for melt extrusion, cooling and solidifying on the surface of a casting roll, longitudinally stretching, and then coating with a coating liquid. After coating, drying is performed, and then transverse stretching is performed to obtain a coated matte film;

[0027] In the coating, the mass ratio of the pre-crystallized and dried A-layer polyester resin slice, the pre-crystallized and dried B-layer polyester resin slice, and the pre-crystallized and dried C-layer polyester resin slice is 10-12:95-110:9-12;

[0028] In the melt extrusion, the heating zone temperature of the No. 1 twin-screw extruder and the No. 2 twin-screw extruder is 256-265°C, and the heating zone temperature of the single-screw extruder is 270-285°C;

[0029] The temperature during the longitudinal stretching is 75-80°C, and the ratio is 3.3-3.5:1;

[0030] The coating thickness of the coating liquid in the coating is 4.5-5 μm;

[0031] The temperature during the drying is 130-135°C and the time is 4-5 minutes;

[0032] The temperature during the transverse stretching is 115-120°C, and the ratio is 3.5-3.7:1;

[0033] The thickness of the coated matte film is 12-30 μm.

[0034] A coated matte film prepared by the above-mentioned preparation method.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) The method for preparing a coated matte PET film of the present invention has a high haze of 51-90%;

[0037] (2) The method for preparing the coated matte PET film of the present invention has good appearance, and the appearance is a milky white matte film;

[0038] (3) The method for preparing a coated matte PET film of the present invention, wherein the surface of the prepared coated matte PET film has no fisheyes or shrinkage cavities;

[0039] (4) The method for preparing a coated matte PET film of the present invention has uniform haze. Ten test points are taken from the prepared coated matte PET film, and the interval between each test point is 20 cm. After the haze of each test point is tested, the difference between the maximum haze and the minimum haze calculated is 1.0-2.1%;

[0040] (5) The method for preparing the coated matte PET film of the present invention has strong coating adhesion and a peel strength of 33.8-36.4 N / cm for the prepared coated matte PET film;

[0041] (6) The method for preparing the coated matte PET film of the present invention avoids the use of wax matting agents, thereby avoiding the influence on the drying speed of the aqueous polyurethane dispersion, and thus the preparation time is short;

[0042] (7) The method for preparing a coated matte PET film of the present invention has strong water resistance. When the coated matte PET film is completely immersed in water and left to stand at room temperature for 168 hours, the peel strength decrease rate is 1.4-2.1%. DETAILED DESCRIPTION

[0043] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific implementation methods of the present invention are now described.

[0044] Example 1

[0045] A method for preparing a coated matte PET film, specifically comprising:

[0046] 1. Preparation of an antistatic agent: 200 g of white carbon black and 1700 mL of a sodium chloride aqueous solution were mixed, stirred at a stirring speed of 300 rpm for 2 h at room temperature, centrifuged at a centrifugal speed of 11000 rpm for 14 min, a precipitate was taken, washed with deionized water, dried, mixed with 1700 mL of a polydiallyldimethylammonium chloride aqueous solution, stirred at a stirring speed of 300 rpm for 2 h at room temperature, centrifuged at a centrifugal speed of 11000 rpm for 14 min, a precipitate was taken, washed with deionized water, dried, mixed with 1600 mL of a calcium chloride aqueous solution, stirred at a stirring speed of 300 rpm for 1 h at room temperature, centrifuged at a centrifugal speed of 11000 rpm for 14 min, a precipitate was taken, washed with deionized water, dried, mixed with 2400 mL of a carboxymethyl cellulose aqueous solution, stirred at a stirring speed of 300 rpm for 1 h at room temperature, centrifuged at a centrifugal speed of 11000 rpm for 14 min, a precipitate was taken, washed with deionized water, and dried to obtain an antistatic agent;

[0047] The average particle size of the white carbon black is 30 nm;

[0048] The mass concentration of the sodium chloride aqueous solution is 5%;

[0049] The mass concentration of the polydiallyldimethylammonium chloride aqueous solution is 1%;

[0050] The mass concentration of the calcium chloride aqueous solution is 5%;

[0051] The mass concentration of the carboxymethyl cellulose aqueous solution is 2%;

[0052] 2. Preparation of matting agent: 200g talcum powder and 1200mL sodium stearate aqueous solution were mixed, stirred at 80°C at a stirring speed of 300rpm for 2h, centrifuged at a centrifugal speed of 4000rpm for 5min, the precipitate was taken, washed with deionized water, dried, and then mixed with 1300mL calcium chloride aqueous solution, stirred at a stirring speed of 300rpm for 1.5h at room temperature, centrifuged at a centrifugal speed of 4000rpm for 5min, the precipitate was taken, washed with deionized water, dried, and then mixed with 1300mL stearyl alcohol anhydrous ethanol solution, stirred at a stirring speed of 300rpm for 2h at room temperature, centrifuged at a centrifugal speed of 4000rpm for 5min, the precipitate was taken, washed with anhydrous ethanol, and dried to obtain a matting agent;

[0053] The mass concentration of the sodium stearate aqueous solution is 1%;

[0054] The average particle size of the talc is 10 μm;

[0055] The mass concentration of the calcium chloride aqueous solution is 5%;

[0056] The mass concentration of the stearyl alcohol anhydrous ethanol solution is 1%;

[0057] 3. Prepare coating liquid: Mix the aqueous polyurethane dispersion, antistatic agent, matting agent and aqueous silicone defoamer, stir at room temperature at a stirring speed of 900 rpm for 30 minutes, add acrylic leveling agent, wear resistance agent and 3-aminopropyltrimethoxysilane, continue stirring for 10 minutes, add polycarbodiimide, continue stirring for 4 minutes to obtain coating liquid;

[0058] The aqueous polyurethane dispersion is a polycarbonate-type aqueous polyurethane dispersion, and the solid content is 35% by mass;

[0059] The mass ratio of waterborne polyurethane dispersion, antistatic agent, matting agent, waterborne silicone defoamer, acrylic leveling agent, wear-resistant agent, 3-aminopropyltrimethoxysilane, and polycarbodiimide is 100:4:4:0.3:2.4:2:2.5:1.3;

[0060] The model of the wear-resistant agent is CUBD-NM01;

[0061] 4. Coating: The A-layer polyester resin slices after pre-crystallization and drying, the B-layer polyester resin slices after pre-crystallization and drying, and the C-layer polyester resin slices after pre-crystallization and drying are respectively put into the No. 1 twin-screw extruder, the single-screw extruder, and the No. 2 twin-screw extruder for melt extrusion, and the heating zone temperature of the No. 1 twin-screw extruder and the No. 2 twin-screw extruder is controlled to be 256°C, and the heating zone temperature of the single-screw extruder is controlled to be 270°C, and then after cooling and curing on the surface of the casting roller, longitudinal stretching is performed, and the longitudinal stretching temperature is controlled to be 75°C, and the ratio is 3.3:1, and then the coating liquid is used for coating, and the coating thickness of the coating liquid during the coating is controlled to be 4.5μm. After the coating is completed, it is dried at 130°C for 4min, and then transverse stretching is performed, and the transverse stretching temperature is 115°C, and the ratio is 3.5:1, to obtain a coated matte film;

[0062] The mass ratio of the pre-crystallized and dried A-layer polyester resin slice, the pre-crystallized and dried B-layer polyester resin slice, and the pre-crystallized and dried C-layer polyester resin slice is 10:95:9;

[0063] The thickness of the coated matte film is 12 μm.

[0064] This embodiment also provides a coated matte film prepared by the aforementioned preparation method.

[0065] Example 2

[0066] A method for preparing a coated matte PET film, specifically comprising:

[0067] 1. Preparation of an antistatic agent: 200 g of white carbon black and 1900 mL of a sodium chloride aqueous solution were mixed, stirred at a stirring speed of 350 rpm for 2 h at room temperature, centrifuged at a centrifugal speed of 11000 rpm for 15 min, a precipitate was taken, washed with deionized water, dried, mixed with 1900 mL of a polydiallyldimethylammonium chloride aqueous solution, stirred at a stirring speed of 350 rpm for 2 h at room temperature, centrifuged at a centrifugal speed of 11000 rpm for 15 min, a precipitate was taken, washed with deionized water, dried, mixed with 1700 mL of a calcium chloride aqueous solution, stirred at a stirring speed of 350 rpm for 1.5 h at room temperature, centrifuged at a centrifugal speed of 11000 rpm for 15 min, a precipitate was taken, washed with deionized water, dried, mixed with 2500 mL of a carboxymethyl cellulose aqueous solution, stirred at a stirring speed of 350 rpm for 1.5 h at room temperature, centrifuged at a centrifugal speed of 11000 rpm for 15 min, a precipitate was taken, washed with deionized water, and dried to obtain an antistatic agent;

[0068] The average particle size of the white carbon black is 30 nm;

[0069] The mass concentration of the sodium chloride aqueous solution is 5%;

[0070] The mass concentration of the polydiallyldimethylammonium chloride aqueous solution is 1%;

[0071] The mass concentration of the calcium chloride aqueous solution is 5%;

[0072] The mass concentration of the carboxymethyl cellulose aqueous solution is 2%;

[0073] 2. Preparation of a matting agent: 200 g of talc and 1250 mL of a sodium stearate aqueous solution were mixed, stirred at 82 ° C at a stirring speed of 350 rpm for 2.5 h, centrifuged at a centrifugal speed of 4500 rpm for 5 min, a precipitate was taken, washed with deionized water, dried, and then mixed with 1400 mL of a calcium chloride aqueous solution, stirred at a stirring speed of 350 rpm for 1.5 h at room temperature, centrifuged at a centrifugal speed of 4500 rpm for 5 min, a precipitate was taken, washed with deionized water, dried, and then mixed with 1400 mL of anhydrous stearyl alcohol solution, stirred at a stirring speed of 350 rpm for 2 h at room temperature, centrifuged at a centrifugal speed of 4500 rpm for 5 min, a precipitate was taken, washed with anhydrous ethanol, and dried to obtain a matting agent;

[0074] The mass concentration of the sodium stearate aqueous solution is 1%;

[0075] The average particle size of the talc is 10 μm;

[0076] The mass concentration of the calcium chloride aqueous solution is 5%;

[0077] The mass concentration of the stearyl alcohol anhydrous ethanol solution is 1%;

[0078] 3. Prepare coating liquid: Mix the aqueous polyurethane dispersion, antistatic agent, matting agent and aqueous silicone defoamer, stir at room temperature at a stirring speed of 950 rpm for 35 minutes, add acrylic leveling agent, wear resistance agent and 3-aminopropyltrimethoxysilane, continue stirring for 11 minutes, add polycarbodiimide, continue stirring for 4 minutes to obtain coating liquid;

[0079] The aqueous polyurethane dispersion is a polycarbonate-type aqueous polyurethane dispersion, and the solid content is 35% by mass;

[0080] The mass ratio of waterborne polyurethane dispersion, antistatic agent, matting agent, waterborne silicone defoamer, acrylic leveling agent, wear-resistant agent, 3-aminopropyltrimethoxysilane, and polycarbodiimide is 100:4.2:5.5:0.3:2.5:2.2:2.8:1.3;

[0081] The model of the wear-resistant agent is CUBD-NM01;

[0082] 4. Coating: The A-layer polyester resin slices after pre-crystallization and drying, the B-layer polyester resin slices after pre-crystallization and drying, and the C-layer polyester resin slices after pre-crystallization and drying are respectively put into the No. 1 twin-screw extruder, the single-screw extruder, and the No. 2 twin-screw extruder for melt extrusion, and the heating zone temperature of the No. 1 twin-screw extruder and the No. 2 twin-screw extruder is controlled to be 260°C, and the heating zone temperature of the single-screw extruder is controlled to be 280°C. After cooling and solidification on the surface of the casting roller, longitudinal stretching is performed, and the longitudinal stretching temperature is controlled to be 78°C, and the ratio is 3.4:1. Then, the coating liquid is used for coating, and the coating thickness of the coating liquid during coating is controlled to be 4.7μm. After the coating is completed, it is dried at 132°C for 4.5min, and then transverse stretching is performed, and the transverse stretching temperature is 118°C, and the ratio is 3.6:1, to obtain a coated matte film;

[0083] The mass ratio of the pre-crystallized and dried A-layer polyester resin slice, the pre-crystallized and dried B-layer polyester resin slice, and the pre-crystallized and dried C-layer polyester resin slice is 11:104:10;

[0084] The thickness of the coated matte film is 21 μm.

[0085] This embodiment also provides a coated matte film prepared by the aforementioned preparation method.

[0086] Example 3

[0087] A method for preparing a coated matte PET film, specifically comprising:

[0088] 1. Preparation of an antistatic agent: 200 g of white carbon black and 2000 mL of a sodium chloride aqueous solution were mixed, stirred at a stirring speed of 400 rpm for 2.5 h at room temperature, centrifuged at a centrifugal speed of 12000 rpm for 16 min, a precipitate was taken, washed with deionized water, dried, mixed with 2000 mL of a polydiallyldimethylammonium chloride aqueous solution, stirred at a stirring speed of 400 rpm for 2.5 h at room temperature, centrifuged at a centrifugal speed of 12000 rpm for 16 min, a precipitate was taken, washed with deionized water, dried, mixed with 1800 mL of a calcium chloride aqueous solution, stirred at a stirring speed of 400 rpm for 1.5 h at room temperature, centrifuged at a centrifugal speed of 12000 rpm for 16 min, a precipitate was taken, washed with deionized water, dried, mixed with 2600 mL of a carboxymethyl cellulose aqueous solution, stirred at a stirring speed of 400 rpm for 1.5 h at room temperature, centrifuged at a centrifugal speed of 12000 rpm for 16 min, a precipitate was taken, washed with deionized water, and dried to obtain an antistatic agent;

[0089] The average particle size of the white carbon black is 30 nm;

[0090] The mass concentration of the sodium chloride aqueous solution is 5%;

[0091] The mass concentration of the polydiallyldimethylammonium chloride aqueous solution is 1%;

[0092] The mass concentration of the calcium chloride aqueous solution is 5%;

[0093] The mass concentration of the carboxymethyl cellulose aqueous solution is 2%;

[0094] 2. Preparation of a matting agent: 200 g of talc and 1300 mL of a sodium stearate aqueous solution were mixed, stirred at 85 ° C at a stirring speed of 400 rpm for 2.5 h, centrifuged at a centrifugal speed of 5000 rpm for 6 min, a precipitate was taken, washed with deionized water, dried, and then mixed with 1500 mL of a calcium chloride aqueous solution, stirred at a stirring speed of 400 rpm for 2 h at room temperature, centrifuged at a centrifugal speed of 5000 rpm for 6 min, a precipitate was taken, washed with deionized water, dried, and then mixed with 1500 mL of anhydrous stearyl alcohol solution, stirred at a stirring speed of 400 rpm for 2.5 h at room temperature, centrifuged at a centrifugal speed of 5000 rpm for 6 min, a precipitate was taken, washed with anhydrous ethanol, and dried to obtain a matting agent;

[0095] The mass concentration of the sodium stearate aqueous solution is 1%;

[0096] The average particle size of the talc is 10 μm;

[0097] The mass concentration of the calcium chloride aqueous solution is 5%;

[0098] The mass concentration of the stearyl alcohol anhydrous ethanol solution is 1%;

[0099] 3. Prepare coating liquid: Mix the aqueous polyurethane dispersion, antistatic agent, matting agent and aqueous silicone defoamer, stir at room temperature at a stirring speed of 1000 rpm for 40 minutes, add acrylic leveling agent, wear resistance agent and 3-aminopropyltrimethoxysilane, continue stirring for 12 minutes, add polycarbodiimide, continue stirring for 5 minutes, and obtain coating liquid;

[0100] The aqueous polyurethane dispersion is a polycarbonate-type aqueous polyurethane dispersion, and the solid content is 35% by mass;

[0101] The mass ratio of waterborne polyurethane dispersion, antistatic agent, matting agent, waterborne silicone defoamer, acrylic leveling agent, wear-resistant agent, 3-aminopropyltrimethoxysilane, and polycarbodiimide is 100:4.5:6.5:0.4:2.7:2.3:3:1.4;

[0102] The model of the wear-resistant agent is CUBD-NM01;

[0103] 4. Coating: The A-layer polyester resin slices after pre-crystallization and drying, the B-layer polyester resin slices after pre-crystallization and drying, and the C-layer polyester resin slices after pre-crystallization and drying are respectively put into the No. 1 twin-screw extruder, the single-screw extruder, and the No. 2 twin-screw extruder for melt extrusion, and the heating zone temperature of the No. 1 twin-screw extruder and the No. 2 twin-screw extruder is controlled to be 265°C, and the heating zone temperature of the single-screw extruder is controlled to be 285°C. After cooling and solidification on the surface of the casting roll, longitudinal stretching is performed, and the longitudinal stretching temperature is controlled to be 80°C, and the ratio is 3.5:1. Then, the coating liquid is used for coating, and the coating thickness of the coating liquid during the coating is controlled to be 5μm. After the coating is completed, it is dried at 135°C for 5 minutes, and then transverse stretching is performed, and the transverse stretching temperature is 120°C, and the ratio is 3.7:1, to obtain a coated matte film;

[0104] The mass ratio of the pre-crystallized and dried A-layer polyester resin slice, the pre-crystallized and dried B-layer polyester resin slice, and the pre-crystallized and dried C-layer polyester resin slice is 12:110:12;

[0105] The thickness of the coated matte film is 30 μm.

[0106] This embodiment also provides a coated matte film prepared by the aforementioned preparation method.

[0107] Comparative Example 1

[0108] On the basis of the preparation method of Example 2, the step of preparing the antistatic agent in step 1 is omitted, and in the step of preparing the coating solution in step 3, a mixture of white carbon black and the antistatic agent MI00-10T is used in place of the antistatic agent in equal mass;

[0109] The average particle size of the white carbon black is 30 nm;

[0110] The mass ratio of the white carbon black to the antistatic agent MI00-10T in the mixture of the white carbon black and the antistatic agent MI00-10T is 4:1.

[0111] The rest of the technical solutions are consistent with those in Example 2.

[0112] Comparative Example 2

[0113] On the basis of the preparation method of Example 2, the step of preparing the matting agent in step 2 is omitted, and in the step of preparing the coating solution in step 3, a mixture of white carbon black and antistatic agent MI00-10T is used in place of the antistatic agent in equal mass;

[0114] The average particle size of the talc powder is 10 μm.

[0115] The rest of the technical solutions are consistent with those in Example 2.

[0116] Performance Test 1

[0117] The haze, appearance, presence of fisheyes and shrinkage cavities, and peel strength of the coated matte PET films prepared in Examples 1-3 and Comparative Examples 1-2 were tested, and the test results are as follows:

[0118]

[0119] Performance Test 2

[0120] Ten test points were taken from the coated matte PET films prepared in Examples 1-3 and Comparative Examples 1-2, with the interval between each test point being 20 cm, and then the haze of each test point was tested, and the difference between the maximum haze and the minimum haze was calculated. The calculation results are as follows:

[0121]

[0122] Performance Test 3

[0123] The peel strength of the coated matte PET films prepared in Examples 1-3 and Comparative Examples 1-2 was tested, and then the coated matte PET films prepared in Examples 1-3 and Comparative Examples 1-2 were completely immersed in water, and after standing at room temperature for 168 hours, the peel strength was tested, and the peel strength decrease rate was calculated. The calculation results are as follows:

[0124]

[0125] It can be seen from the results of performance tests 1-3 that the haze, appearance and peel strength results of the coated matte PET film prepared in Comparative Examples 1-2 are worse than those of the coated matte PET film prepared in Example 2, and compared with the coated matte PET film prepared in Example 2, the coated matte PET film prepared in Comparative Example 1 still has fisheyes and shrinkage holes, as well as uneven haze problems, and the coated matte PET film prepared in Comparative Examples 1-2 still has fisheyes and shrinkage holes, as well as uneven haze and poor water resistance.

[0126] In Examples 1-3, an antistatic agent and a matting powder are used in the step of preparing a coating solution, wherein the preparation method of the antistatic agent is to first treat white carbon black with an aqueous sodium chloride solution, so that chloride ions are adsorbed on the surface of white carbon black, and then treat it with an aqueous polydiallyldimethylammonium chloride solution, and polydiallyldimethylammonium chloride is continuously adsorbed on the surface of white carbon black through the adsorption of chloride ions by the aqueous polydiallyldimethylammonium chloride solution, and then treat it with an aqueous calcium chloride solution, and calcium ions are continuously adsorbed on the surface of white carbon black through the adsorption of calcium ions by the aqueous polydiallyldimethylammonium chloride solution, and finally treat it with an aqueous carboxymethyl cellulose solution, and an interpenetrating network is formed with polydiallyldimethylammonium chloride through the interaction between carboxymethyl cellulose and calcium ions, wherein the sodium ions and ammonium chloride ions in the antistatic agent can play an antistatic role and can also promote the dispersion of white carbon black, and the carboxymethyl cellulose can promote the curing of the aqueous polyurethane dispersion, and in addition, the presence of calcium ions can also play a matting role;

[0127] The preparation method of the matting powder comprises the following steps: firstly treating talc powder with a sodium stearate aqueous solution, wherein the sodium stearate is adsorbed on the surface and interlayers of the talc powder through intermolecular forces; then treating the talc powder with a calcium chloride aqueous solution, wherein calcium ions are combined with stearic acid groups adsorbed on the surface of the talc powder to generate calcium stearate, thereby obtaining talc powder coated with calcium stearate; and then treating the talc powder with a stearyl alcohol anhydrous ethanol solution, wherein the stearyl alcohol is combined with the sodium stearate between the talc powder layers through intermolecular forces and coated on the surface of the talc powder coated with calcium stearate, wherein the calcium stearate and the talc powder can play a synergistic matting role, the stearyl alcohol can play a role in improving the fluidity of the matting powder, and the sodium stearate and stearyl alcohol between the layers both contain long-chain alkyl groups, thereby improving the water resistance of a coated matte PET film.

[0128] Unless otherwise specified, all percentages used in the present invention are by mass.

[0129] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a coated matte PET film, characterized in that: The method comprises the following steps: preparing an antistatic agent, preparing a matting agent, preparing a coating liquid, and coating; The preparation of the antistatic agent comprises mixing white carbon black and a sodium chloride aqueous solution, stirring at room temperature, centrifuging, taking a precipitate, washing, and drying; mixing with a polydiallyldimethylammonium chloride aqueous solution, stirring at room temperature, centrifuging, taking a precipitate, washing, and drying; mixing with a calcium chloride aqueous solution, stirring at room temperature, centrifuging, taking a precipitate, washing with deionized water, and drying; mixing with a carboxymethyl cellulose aqueous solution, stirring at room temperature, centrifuging, taking a precipitate, washing, and drying to obtain the antistatic agent; The matting agent is prepared by mixing talcum powder and sodium stearate aqueous solution, stirring at 80-85° C., centrifuging, taking a precipitate, washing, drying, and then mixing with calcium chloride aqueous solution, stirring at room temperature, centrifuging, taking a precipitate, washing, drying, and then mixing with stearyl alcohol anhydrous ethanol solution, stirring at room temperature, centrifuging, taking a precipitate, washing, and drying to obtain a matting agent; The coating liquid is prepared by mixing an aqueous polyurethane dispersion, an antistatic agent, a matting agent, and an aqueous silicone defoamer, stirring at room temperature, adding an acrylic leveling agent, an anti-wear agent, and 3-aminopropyltrimethoxysilane, continuing to stir, adding polycarbodiimide, and continuing to stir to obtain a coating liquid; The coating comprises the following steps: the pre-crystallized and dried A-layer polyester resin slice, the pre-crystallized and dried B-layer polyester resin slice, and the pre-crystallized and dried C-layer polyester resin slice are respectively put into a No. 1 twin-screw extruder, a single-screw extruder, and a No. 2 twin-screw extruder for melt extrusion, and then cooled and solidified on the surface of a casting roller, longitudinally stretched, and then coated with a coating liquid, dried after coating, and then transversely stretched to obtain a coated matte film.

2. The method for preparing a coated matte PET film according to claim 1, characterized in that: In the preparation of the antistatic agent, the mass volume ratio of white carbon black, sodium chloride aqueous solution, polydiallyldimethylammonium chloride aqueous solution, calcium chloride aqueous solution and carboxymethyl cellulose aqueous solution is 200g:1700-2000mL:1700-2000mL:1600-1800mL:2400-2600mL.

3. The method for preparing a coated matte PET film according to claim 1, characterized in that: In the preparation of the antistatic agent, the average particle size of the white carbon black is 30 nm; The mass concentration of the sodium chloride aqueous solution is 5%; The mass concentration of the polydiallyldimethylammonium chloride aqueous solution is 1%; The mass concentration of the calcium chloride aqueous solution is 5%; The mass concentration of the carboxymethyl cellulose aqueous solution is 2%.

4. The method for preparing a coated matte PET film according to claim 1, characterized in that: In the preparation of the matting agent, the mass volume ratio of talcum powder, sodium stearate aqueous solution, calcium chloride aqueous solution and stearyl alcohol anhydrous ethanol solution is 200g:1200-1300mL:1300-1500mL:1300-1500mL.

5. The method for preparing a coated matte PET film according to claim 1, characterized in that: In the preparation of the matting agent, the mass concentration of the sodium stearate aqueous solution is 1%; The average particle size of the talc is 10 μm; The mass concentration of the calcium chloride aqueous solution is 5%; The mass concentration of the stearyl alcohol anhydrous ethanol solution is 1%.

6. The method for preparing a coated matte PET film according to claim 1, characterized in that: In the coating liquid, the mass ratio of the aqueous polyurethane dispersion, the antistatic agent, the matting agent, the aqueous silicone defoaming agent, the acrylic leveling agent, the wear-resistant agent, the 3-aminopropyltrimethoxysilane, and the polycarbodiimide is 100:4-4.5:4-6.5:0.3-0.4:2.4-2.7:2-2.3:2.5-3:1.3-1.4; The aqueous polyurethane dispersion is a polycarbonate-type aqueous polyurethane dispersion, and the solid content is 35% by mass; The model of the anti-wear agent is CUBD-NM01.

7. The method for preparing a coated matte PET film according to claim 1, characterized in that: In the coating, the mass ratio of the pre-crystallized and dried A-layer polyester resin slice, the pre-crystallized and dried B-layer polyester resin slice, and the pre-crystallized and dried C-layer polyester resin slice is 10-12:95-110:9-12.

8. The method for preparing a coated matte PET film according to claim 1, characterized in that: In the coating, in the melt extrusion, the heating zone temperature of the No. 1 twin-screw extruder and the No. 2 twin-screw extruder is 256-265°C, and the heating zone temperature of the single-screw extruder is 270-285°C; The temperature during the longitudinal stretching is 75-80°C, and the ratio is 3.3-3.5:1; The coating thickness of the coating liquid in the coating is 4.5-5 μm; The temperature during the drying is 130-135°C and the time is 4-5 minutes; The temperature during the transverse stretching is 115-120°C, and the ratio is 3.5-3.7:1; The thickness of the coated matte film is 12-30 μm.

9. A coated matte film prepared by the preparation method according to any one of claims 1 to 8.

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