On-line coating polyester film and preparation method thereof

Abstract

The invention provides an online coating polyester film and a preparation method thereof, and relates to the technical field of polyester films, the polyester film comprises a base film and a priming coat arranged on at least one surface of the base film; wherein the bottom coating layer is obtained by coating a bottom coating solution; the base coating liquid is prepared according to the following method: respectively preparing a water-based acrylic emulsion, a polyester solution and a polyurethane prepolymer; and then adding the polyester solution and the polyurethane prepolymer into the aqueous acrylic acid solution to obtain the primer solution. According to the on-line coating polyester film provided by the invention, the water-based polypropylene, water-based polyester and water-based polyurethane mixed coating is introduced to the surface of the polyester film base film, and the synergistic effect of the components is utilized, so that the prepared on-line coating polyester film has excellent adhesion performance to different types of UV printing ink.

Description

Technical Field

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

[0002] Biaxially oriented polyester film is a film material with excellent performance. Its excellent mechanical properties make it widely used in packaging, electronics and other fields. In particular, UV inkjet printing materials have become the preferred solution for printing barcodes, QR codes and anti-counterfeiting labels in the field of high-end packaging due to their fast curing rate and good wear resistance.

[0003] However, the high shrinkage stress of UV ink printing materials during the curing process leads to insufficient adhesion on polyester film, and usually requires specially treated polyester film to ensure good adhesion, while ordinary corona treatment cannot well meet the downstream use requirements; in addition, the existing single type of online coated polyester film can only be used for some UV ink printing, which limits its application range. Therefore, how to develop an online coated polyester film that is compatible with multiple UV ink printing and has excellent adhesion is a key technical difficulty. Summary of the invention

[0004] In order to solve the problem that the online coated polyester film in the prior art is not compatible with a variety of UV ink printing and has excellent adhesion, the present invention discloses an online coated polyester film, which introduces a mixed coating of water-based polypropylene, water-based polyester and water-based polyurethane on the surface of a polyester film base film, fully utilizes the characteristics of polypropylene, polyester and polyurethane, and can improve the adhesion performance of the online coated polyester film to different types of UV inks, thereby solving the problem that the online coated polyester film in the prior art is not compatible with a variety of UV ink printing and has excellent adhesion.

[0005] The technical solution adopted by the present invention to solve its technical problem is: An online coated polyester film, the polyester film comprising a base film and a primer layer disposed on at least one side of the base film; The primer layer is obtained by coating a primer liquid; The primer solution is prepared as follows: S01: preparing a water-based acrylic emulsion using acrylic acid, an initiator, a dispersant and water as raw materials; S02: using dicarboxylic acid, alkyl diacid, olefin diacid, alkyl glycol and trimethylolpropane as raw materials to prepare a polyester solution; S03: preparing a polyurethane prepolymer using oligomer diol, catalyst, diisocyanate compound, hydrophilic monomer and hydroxide as raw materials; S04: adding the polyester solution and the polyurethane prepolymer into the aqueous acrylic solution to obtain a primer solution.

[0006] Optionally, the mass ratio of the acrylic solution, the polyester solution and the polyurethane prepolymer is (0.5-3):(0.5-3):1.

[0007] Optionally, the mass ratio of the dicarboxylic acid, alkyl diacid, olefin diacid, alkyl glycol and trimethylolpropane in step S02 is (20-50):(5-10):(10-30):(10-30):(5-10).

[0008] Optionally, the mass ratio of the oligomer diol, the catalyst, the diisocyanate compound and the hydrophilic monomer in step S03 is (10-50):(2-9):(10-40):(2-9).

[0009] Optionally, the alkyl diacid is selected from at least one of oxalic acid, malonic acid, succinic acid, glutaric acid and adipic acid.

[0010] Optionally, the olefin diacid is selected from at least one of fumaric acid, maleic acid and propylene acid.

[0011] Optionally, the alkyl glycol is selected from at least one of neopentyl glycol, hexylene glycol, propylene glycol and butanediol.

[0012] Optionally, the oligomer diol is selected from at least one of polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polycaprolactone diol, polycarbonate diol, polyoxyethylene-polyoxypropylene-polyoxyethylene glycol, polyethylene adipate diol, polybutylene adipate diol, polyethylene terephthalate diol, polybutylene terephthalate diol, α, ω-dihydroxy polydimethylsiloxane, dihydroxy polydiphenylsiloxane, and dihydroxy polytrifluoropropylmethylsiloxane.

[0013] Optionally, the diisocyanate compound is selected from at least one of 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, isophorone diisocyanate, diphenylmethane 4,4-diisocyanate, methylcyclohexyl diisocyanate, and 2,2,4-trimethylhexane diisocyanate.

[0014] Another object of the present invention is to provide a method for preparing the online coated polyester film as described above, characterized in that it comprises the following steps: After the primer liquid is stirred evenly, it is coated on a single surface of the longitudinal stretching sheet of the base film, and then enters the transverse stretching area for stretching. Finally, after shaping, cooling and winding, an online coated polyester film is obtained.

[0015] The present invention has the following beneficial effects: The online coated polyester film provided by the present invention introduces a mixed coating of water-based polypropylene, water-based polyester and water-based polyurethane on the surface of the polyester film base film, fully utilizing the characteristics of polypropylene, polyester and polyurethane, as well as the synergistic effect between the components, so that the prepared online coated polyester film has excellent adhesion performance to different types of UV inks, thereby solving the problems in the prior art that UV inks have poor adhesion to the surface of the polyester film and that a single type of coating can only be suitable for printing with some UV inks. DETAILED DESCRIPTION

[0016] The present invention is now further described in detail. The embodiments described below are exemplary and intended to be used to explain the present invention, but cannot be understood as limiting the present invention. All other embodiments obtained by ordinary technicians in this field without creative work based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0017] In order to solve the problem that the online coated polyester film in the prior art is not compatible with a variety of UV ink printing and has excellent adhesion, the present invention provides an online coated polyester film, the polyester film comprising a base film and a primer layer disposed on at least one side of the base film; The primer layer is obtained by coating a primer liquid; The primer solution was prepared as follows: S01: preparing a water-based acrylic emulsion using acrylic acid, an initiator, a dispersant and water as raw materials; S02: using dicarboxylic acid, alkyl diacid, olefin diacid, alkyl glycol and trimethylolpropane as raw materials to prepare a polyester solution; S03: preparing a polyurethane prepolymer using oligomer diol, catalyst, diisocyanate compound, hydrophilic monomer and hydroxide as raw materials; S04: adding the polyester solution and the polyurethane prepolymer into the aqueous acrylic solution to obtain a primer solution.

[0018] The online coated polyester film provided by the present invention introduces a mixed coating of water-based polypropylene, water-based polyester and water-based polyurethane on the surface of the polyester film base film, fully utilizing the characteristics of polypropylene, polyester and polyurethane, as well as the synergistic effect between the components, so that the prepared online coated polyester film has excellent adhesion performance to different types of UV inks, thereby solving the problems in the prior art that UV inks have poor adhesion to the surface of the polyester film and that a single type of coating can only be suitable for printing with some UV inks.

[0019] In order to adapt to different application requirements and environmental conditions and ensure the stability and uniformity of the primer, the primer preferably prepared in the present invention has a mass fraction of nano-silicon dioxide of 0.005wt%-40wt% and a solid content of 0.2%-45%.

[0020] Specifically, in order to ensure the effective synergistic effect of various components and further improve the comprehensive performance of the online coated polyester film of the present invention, the mass ratio of the acrylic acid solution, the polyester solution and the polyurethane prepolymer is preferably (0.5-3):(0.5-3):1.

[0021] The mass ratio of dicarboxylic acid, alkyl diacid, olefin diacid, alkyl glycol and trimethylolpropane in step S02 of the present invention is preferably (20-50):(5-10):(10-30):(10-30):(5-10).

[0022] In the preferred embodiment of the present invention, the mass ratio of the oligomer diol, the catalyst, the diisocyanate compound, and the hydrophilic monomer in step S03 is (10-50):(2-9):(10-40):(2-9).

[0023] In the present invention, the dicarboxylic acid is preferably at least one selected from terephthalic acid, isophthalic acid, phthalic acid, 2,5-furandicarboxylic acid, and an alkyl dicarboxylic acid compound containing 5 to 15 carbon atoms.

[0024] In the present invention, the alkyl diacid is preferably selected from at least one of oxalic acid, malonic acid, succinic acid, glutaric acid and adipic acid.

[0025] In the present invention, the olefin diacid is preferably selected from at least one of fumaric acid, maleic acid and propylene acid.

[0026] In the present invention, the alkyl glycol is preferably selected from at least one of neopentyl glycol, hexylene glycol, propylene glycol and butylene glycol.

[0027] The preferred oligomer diol of the present invention is selected from at least one of polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polycaprolactone diol, polycarbonate diol, polyoxyethylene-polyoxypropylene-polyoxyethylene glycol, polyethylene adipate diol, polybutylene adipate diol, polyethylene terephthalate diol, polybutylene terephthalate diol, α, ω-dihydroxy polydimethylsiloxane, dihydroxy polydiphenylsiloxane, and dihydroxy polytrifluoropropylmethylsiloxane.

[0028] The diisocyanate compound of the present invention is preferably at least one selected from 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, isophorone diisocyanate, diphenylmethane 4,4-diisocyanate, methylcyclohexyl diisocyanate, and 2,2,4-trimethylhexane diisocyanate.

[0029] In the present invention, the hydrophilic monomer is preferably selected from at least one of dimethylol propionic acid, dimethylol butyric acid, and sodium 1,2-dihydroxy-3-propanesulfonate.

[0030] The preferred catalyst of the present invention is dibutyltin dilaurate.

[0031] The preferred hydroxide of the present invention is potassium hydroxide.

[0032] Another object of the present invention is to provide a method for preparing the online coating polyester film as described above, characterized in that it comprises the following steps: After the primer liquid is stirred evenly, it is coated on a single surface of the longitudinal stretching sheet of the base film, and then enters the transverse stretching area for stretching. Finally, after shaping, cooling and winding, an online coated polyester film is obtained.

[0033] The preparation method of the online coated polyester film provided by the present invention introduces a mixed coating of water-based polypropylene, water-based polyester and water-based polyurethane on the surface of a polyester film base film, fully utilizing the characteristics of polypropylene, polyester and polyurethane, not only significantly improving the adhesion performance of the polyester film to UV ink, making it adaptable to a wider range of ink types, but also simplifying the production process, reducing the preparation cost, making the production process more efficient and the product performance more stable; in addition, due to the uniformity of the coating and the stability of the surface tension of the film, the produced polyester film has higher consistency and reliability.

[0034] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below.

[0035] Unless otherwise specified, the dicarboxylic acid in each embodiment of the present invention is terephthalic acid; the alkyl diacid is oxalic acid; the olefin diacid is fumaric acid; the alkyl diol is propylene glycol; the oligomer diol is polycarbonate diol (PCD2000); the diisocyanate compound is isophorone diisocyanate (IPDI); the hydrophilic monomer is dihydroxymethyl propionic acid (DMPA); the catalyst is dibutyltin dilaurate; the hydroxide is potassium hydroxide; the base film raw material is an optical polyester base material type chip (model FG600, Sinopec Yizheng Chemical Fiber Co., Ltd.) and an optical polyester masterbatch type chip (model FG610, Sinopec Yizheng Chemical Fiber Co., Ltd.), and the mass ratio of FG600 to FG610 is 50:1; the amount of materials used in each embodiment and comparative example is measured in parts by weight.

[0036] This embodiment provides an online coated polyester film, the polyester film comprising a base film and a primer layer disposed on at least one side of the base film; The primer layer is obtained by coating a primer liquid; Wherein, the primer solution is prepared according to the following method: S01: Mix acrylic acid and water in a mass ratio of 1:3, add a dispersant and an initiator; heat to 60°C, stir and react for 3 hours, adjust the pH to 7, and obtain a water-based acrylic emulsion.

[0037] S02: 50 parts of diformic acid are mixed evenly with 10 parts of alkyl diacid, 15 parts of olefin diacid, 15 parts of alkyl glycol and 10 parts of trimethylolpropane, reacted at 80°C for 1.5 hours, then heated to 250°C and heated at 250°C for 10 hours to obtain a polyester solution.

[0038] S03: Add 25 parts of diisocyanate compound to a 1000mL four-necked flask equipped with a stirrer, a thermometer and a reflux condenser, and add 50 parts of oligomer diol and 2 parts of catalyst with a dropping funnel while stirring at room temperature. The dropping speed is controlled within 1.5 hours. After the addition is completed, react at 50±5°C for 1.5 hours, then gradually heat up to 60°C, add 5 parts of hydrophilic monomer, and continue to react for 6 hours. Determine the degree of reaction by toluene-di-n-butylamine back titration method until the NCO group content reaches the theoretical value; then add hydroxide to the resin and react for 1.5 hours to obtain a polyurethane prepolymer.

[0039] S04: Add the polyester solution and the polyurethane prepolymer into the aqueous acrylic solution at a mass ratio of 1:1:1, stirring at a high speed while adding, to obtain a primer solution.

[0040] The online coated polyester film provided in this embodiment is prepared according to the following method: S1: feeding the base film raw material into the corresponding extrusion system for melt extrusion at a temperature of 255° C. to obtain a base film melt; S2: After the base film melt flows through the die, it forms an unoriented cast slab on the rotating cooling roller; S3: preheating the cooled cast thick sheet and longitudinally stretching it by 2.8 times to obtain a longitudinally stretched film; S4: coating the primer liquid on at least one surface of the longitudinally stretched film to obtain a film coated with the primer liquid; S5: The film coated with the primer is held by a clip and introduced into a preheating zone for transverse stretching. After preheating and drying at 90°C, the film is transversely stretched 2.5 times at 140°C to obtain a stretched film. S6: heat-setting the stretched film at a temperature of 160° C. and winding it up after cooling to obtain an optical polyester film.

[0041] This embodiment provides an online coated polyester film, the polyester film comprising a base film and a primer layer disposed on at least one side of the base film; The primer layer is obtained by coating a primer liquid; Wherein, the primer solution is prepared according to the following method: S01: acrylic acid and water are mixed in a mass ratio of 1:0.5, and a dispersant and an initiator are added; the temperature is raised to 70° C., and the reaction is stirred for 4 hours, and the pH is adjusted to 8 to obtain a water-based acrylic emulsion.

[0042] S02: 20 parts of diformic acid are mixed evenly with 5 parts of alkyl diacid, 10 parts of olefin diacid, 30 parts of alkyl glycol and 5 parts of trimethylolpropane, reacted at 90°C for 2 hours, then heated to 150°C and heated at 150°C for 12 hours to obtain a polyester solution.

[0043] S03: Add 40 parts of diisocyanate compound to a 1000mL four-necked flask equipped with a stirrer, a thermometer and a reflux condenser, and add 10 parts of oligomer diol and 5 parts of catalyst with a dropping funnel while stirring at room temperature. The dropping speed is controlled within 1 hour. After the addition is completed, react at 50±5°C for 1 hour, then gradually heat up to 70°C, add 2 parts of hydrophilic monomer, and continue to react for 8 hours. Determine the degree of reaction by toluene-di-n-butylamine back titration method until the NCO group content reaches the theoretical value; then add hydroxide to the resin and react for 1 hour to obtain a polyurethane prepolymer.

[0044] S04: Add the polyester solution and the polyurethane prepolymer into the aqueous acrylic solution at a mass ratio of 0.5:1:1, stirring at high speed while adding, to obtain a primer solution.

[0045] The online coated polyester film provided in this embodiment is prepared according to the following method: S1: feeding the base film raw material into the corresponding extrusion system for melt extrusion at a temperature of 290° C. to obtain a base film melt; S2: After the base film melt flows through the die, it forms an unoriented cast slab on the rotating cooling roller; S3: preheating the cooled cast thick sheet and longitudinally stretching it 3.8 times to obtain a longitudinally stretched film; S4: coating the primer liquid on at least one surface of the longitudinally stretched film to obtain a film coated with the primer liquid; S5: The film coated with the primer is held by a clip and introduced into a preheating zone for transverse stretching. After preheating and drying at 110° C., it is transversely stretched 4.5 times at 160° C. to obtain a stretched film. S6: heat-setting the stretched film at a temperature of 250° C. and winding it up after cooling to obtain an optical polyester film.

[0046] This embodiment provides an online coated polyester film, the polyester film comprising a base film and a primer layer disposed on at least one side of the base film; The primer layer is obtained by coating a primer liquid; Wherein, the primer solution is prepared according to the following method: S01: acrylic acid and water are mixed in a mass ratio of 1:5, and a dispersant and an initiator are added; the temperature is raised to 65° C., and the reaction is stirred for 3.5 hours, and the pH is adjusted to 7 to obtain a water-based acrylic emulsion.

[0047] S02: 40 parts of diformic acid, 8 parts of alkyl diacid, 30 parts of olefin diacid, 10 parts of alkyl glycol and 8 parts of trimethylolpropane were mixed evenly, reacted at 85°C for 1 hour, then heated to 300°C and heated at 300°C for 5 hours to obtain a polyester solution.

[0048] S03: Add 10 parts of diisocyanate compound to a 1000mL four-necked flask equipped with a stirrer, a thermometer and a reflux condenser, and add 25 parts of oligomer diol and 9 parts of catalyst with a dropping funnel while stirring at room temperature. The dropping speed is controlled within 1.5h. After the addition is completed, react at 50±5℃ for 2h, then gradually heat up to 65℃, add 9 parts of hydrophilic monomer, and continue to react for 7h. Determine the degree of reaction by toluene-di-n-butylamine back titration method until the NCO group content reaches the theoretical value; then add hydroxide to the resin and react for 2h to obtain a polyurethane prepolymer.

[0049] S04: Add the polyester solution and the polyurethane prepolymer into the aqueous acrylic solution at a mass ratio of 0.5:0.5:1, stirring at high speed while adding, to obtain a primer solution.

[0050] The online coated polyester film provided in this embodiment is prepared according to the following method: S1: feeding the base film raw material into the corresponding extrusion system for melt extrusion at a temperature of 270° C. to obtain a base film melt; S2: After the base film melt flows through the die, it forms an unoriented cast slab on the rotating cooling roller; S3: preheating the cooled cast thick sheet and then longitudinally stretching it 3.3 times to obtain a longitudinally stretched film; S4: coating the primer liquid on at least one surface of the longitudinally stretched film to obtain a film coated with the primer liquid; S5: The film coated with the primer is held by a clip and introduced into a preheating zone for transverse stretching. After preheating and drying at 100°C, the film is transversely stretched 3 times at 150°C to obtain a stretched film. S6: heat-setting the stretched film at a temperature of 200° C., and rolling it up after cooling to obtain an optical polyester film.

[0051] This embodiment provides an online coated polyester film, the polyester film comprising a base film and a primer layer disposed on at least one side of the base film; The primer layer is obtained by coating a primer liquid; Wherein, the primer solution is prepared according to the following method: S01: Mix acrylic acid and water in a mass ratio of 1:2, add a dispersant and an initiator; heat to 60°C, stir and react for 3 hours, adjust the pH to 7, and obtain a water-based acrylic emulsion.

[0052] S02: 30 parts of diformic acid, 8 parts of alkyl diacid, 20 parts of olefin diacid, 30 parts of alkyl glycol and 5 parts of trimethylolpropane were mixed evenly, reacted at 80°C for 1 hour, then heated to 200°C and heated at 200°C for 8 hours to obtain a polyester solution.

[0053] S03: Add 30 parts of diisocyanate compound to a 1000mL four-necked flask equipped with a stirrer, a thermometer and a reflux condenser, and add 20 parts of oligomer diol and 4 parts of catalyst with a dropping funnel while stirring at room temperature. The dropping speed is controlled within 1.5h. After the addition is completed, react at 50±5℃ for 1h, then gradually heat up to 60℃, add 2 parts of hydrophilic monomer, and continue to react for 6h. Determine the degree of reaction by toluene-di-n-butylamine back titration method until the NCO group content reaches the theoretical value; then add hydroxide to the resin and react for 1h to obtain a polyurethane prepolymer.

[0054] S04: Add the polyester solution and the polyurethane prepolymer into the aqueous acrylic solution at a mass ratio of 2:2:1, stirring at high speed while adding, to obtain a primer solution.

[0055] The online coated polyester film provided in this embodiment is prepared according to the following method: S1: feeding the base film raw material into the corresponding extrusion system for melt extrusion at a temperature of 280° C. to obtain a base film melt; S2: After the base film melt flows through the die, it forms an unoriented cast slab on the rotating cooling roller; S3: preheating the cooled cast thick sheet and then longitudinally stretching it 3 times to obtain a longitudinally stretched film; S4: coating the primer liquid on at least one surface of the longitudinally stretched film to obtain a film coated with the primer liquid; S5: The film coated with the primer is held by a clip and introduced into a preheating zone for transverse stretching. After preheating and drying at 90°C, the film is transversely stretched 2.5 times at 150°C to obtain a stretched film. S6: heat-setting the stretched film at a temperature of 160° C. and winding it up after cooling to obtain an optical polyester film.

[0056] This embodiment provides an online coated polyester film, the polyester film comprising a base film and a primer layer disposed on at least one side of the base film; The primer layer is obtained by coating a primer liquid; Wherein, the primer solution is prepared according to the following method: S01: Mix acrylic acid and water in a mass ratio of 1:4, add a dispersant and an initiator; raise the temperature to 60-70°C, stir and react for 4 hours, adjust the pH to 7, and obtain a water-based acrylic emulsion.

[0057] S02: 40 parts of diformic acid are mixed evenly with 10 parts of alkyl diacid, 10 parts of olefin diacid, 15 parts of alkyl glycol and 5 parts of trimethylolpropane, reacted at 80°C for 1 hour, then heated to 150°C, and heated at 150°C for 5 to 12 hours to obtain a polyester solution.

[0058] S03: Add 20 parts of diisocyanate compound to a 1000mL four-necked flask equipped with a stirrer, a thermometer and a reflux condenser, and add 20 parts of oligomer diol and 2 parts of catalyst with a dropping funnel while stirring at room temperature. The dropping speed is controlled within 1 hour. After the addition is completed, react at 50±5°C for 1 hour, then gradually heat up to 70°C, add 5 parts of hydrophilic monomer, and continue to react for 6 hours. Determine the degree of reaction by toluene-di-n-butylamine back titration method until the NCO group content reaches the theoretical value; then add hydroxide to the resin and react for 1 hour to obtain a polyurethane prepolymer.

[0059] S04: Add the polyester solution and the polyurethane prepolymer into the aqueous acrylic solution at a mass ratio of 3:2:1, stirring at high speed while adding, to obtain a primer solution.

[0060] The online coated polyester film provided in this embodiment is prepared according to the following method: S1: feeding the base film raw material into the corresponding extrusion system for melt extrusion at a temperature of 270° C. to obtain a base film melt; S2: After the base film melt flows through the die, it forms an unoriented cast slab on the rotating cooling roller; S3: preheating the cooled cast thick sheet and longitudinally stretching it 3.8 times to obtain a longitudinally stretched film; S4: coating the primer liquid on at least one surface of the longitudinally stretched film to obtain a film coated with the primer liquid; S5: The film coated with the primer is held by a clip and introduced into a preheating zone for transverse stretching. After preheating and drying at 110° C., it is transversely stretched 2.5 times at 140° C. to obtain a stretched film. S6: heat-setting the stretched film at a temperature of 160° C. and winding it up after cooling to obtain an optical polyester film.

[0061] This embodiment provides an online coated polyester film, the polyester film comprising a base film and a primer layer disposed on at least one side of the base film; The primer layer is obtained by coating a primer liquid; Wherein, the primer solution is prepared according to the following method: S01: Mix acrylic acid and water in a mass ratio of 1:3, add a dispersant and an initiator; heat to 60°C, stir and react for 3 hours, adjust the pH to 8, and obtain a water-based acrylic emulsion.

[0062] S02: 50 parts of diformic acid are mixed evenly with 5 parts of alkyl diacid, 30 parts of olefin diacid, 10 parts of alkyl glycol and 10 parts of trimethylolpropane, reacted at 90°C for 1 hour, then heated to 200°C and heated at 200°C for 10 hours to obtain a polyester solution.

[0063] S03: Add 10 parts of diisocyanate compound to a 1000mL four-necked flask equipped with a stirrer, a thermometer and a reflux condenser, and add 50 parts of oligomer diol and 3 parts of catalyst with a dropping funnel while stirring at room temperature. The dropping speed is controlled within 1 hour. After the addition is completed, react at 50±5°C for 2 hours, then gradually heat up to 70°C, add 5 parts of hydrophilic monomer, and continue to react for 6 hours. Determine the degree of reaction by toluene-di-n-butylamine back titration method until the NCO group content reaches the theoretical value; then add hydroxide to the resin and react for 1 hour to obtain a polyurethane prepolymer.

[0064] S04: Add the polyester solution and the polyurethane prepolymer into the aqueous acrylic solution at a mass ratio of 3:3:1, stirring at high speed while adding, to obtain a primer solution.

[0065] The online coated polyester film provided in this embodiment is prepared according to the following method: S1: feeding the base film raw material into the corresponding extrusion system for melt extrusion at a temperature of 280° C. to obtain a base film melt; S2: After the base film melt flows through the die, it forms an unoriented cast slab on the rotating cooling roller; S3: preheating the cooled cast thick sheet and longitudinally stretching it 3.5 times to obtain a longitudinally stretched film; S4: coating the primer liquid on at least one surface of the longitudinally stretched film to obtain a film coated with the primer liquid; S5: The film coated with the primer is held by a clip and introduced into a preheating zone for transverse stretching. After preheating and drying at 110° C., it is transversely stretched 4 times at 140° C. to obtain a stretched film. S6: heat-setting the stretched film at a temperature of 200° C., and rolling it up after cooling to obtain an optical polyester film.

[0066] Comparative Example 1 This comparative example is the same as Example 1, except that in Comparative Example 1, the mass ratio of the acrylic acid solution, the polyester solution and the polyurethane prepolymer is 0:1:1.

[0067] Comparative Example 2 This comparative example is the same as Example 1, except that in Comparative Example 2, the mass ratio of the acrylic acid solution, the polyester solution and the polyurethane prepolymer is 1:0:1.

[0068] Comparative Example 3 This comparative example is the same as Example 1, except that in Comparative Example 3, the mass ratio of the acrylic acid solution, the polyester solution and the polyurethane prepolymer is 1:1:0.

[0069] Comparative Example 4 This comparative example is the same as Example 1, except that in Comparative Example 4, the mass ratio of the acrylic acid solution, the polyester solution and the polyurethane prepolymer is 1:0:1.

[0070] Comparative Example 5 This comparative example is the same as Example 1, except that in Comparative Example 5, the mass ratio of the acrylic acid solution, the polyester solution and the polyurethane prepolymer is 0:1:0.

[0071] Comparative Example 6 This comparative example is the same as Example 1, except that in Comparative Example 6, the mass ratio of the acrylic acid solution, the polyester solution and the polyurethane prepolymer is 0:0:1.

[0072] Comparative Example 7 This comparative example is the same as Example 1, except that in Comparative Example 7, the mass ratio of the acrylic acid solution, the polyester solution and the polyurethane prepolymer is 5:4:1.

[0073] Comparative Example 8 This comparative example is the same as Example 1, except that in Comparative Example 8, the mass ratio of the acrylic acid solution, the polyester solution and the polyurethane prepolymer is 5:1:1.

[0074] Comparative Example 9 This comparative example is the same as Example 1, except that in Comparative Example 9, the mass ratio of the acrylic acid solution, the polyester solution and the polyurethane prepolymer is 1:4:1.

[0075] Comparative Example 10 This comparative example is the same as Example 1, except that the acrylic acid solution in Comparative Example 10 is a water-based acrylic resin with a brand number of 7499 (Dow Corning).

[0076] Comparative Example 11 This comparative example is the same as Example 1, except that the polyester solution in Comparative Example 11 is an aqueous polyester resin with a brand name of ST5870 (Toyobo, Japan).

[0077] Comparative Example 12 This comparative example is the same as Example 1, except that the polyurethane prepolymer in Comparative Example 12 is a water-based polyurethane with a brand number of 6274 (Dow Corning).

[0078] Comparative Example 13 This comparative example is the same as Example 1, except that the polyester solution in Comparative Example 13 is prepared as follows: 15 parts of diformic acid are mixed evenly with 10 parts of alkyl diacid, 5 parts of olefin diacid, 10 parts of alkyl glycol, 10 parts of trimethylolpropane and 50 parts of styrene, reacted at 80°C for 1.5 hours, then heated to 250°C and heated at 250°C for 10 hours to obtain a polyester solution.

[0079] Comparative Example 14 This comparative example is the same as Example 1, except that the primer solution in Comparative Example 14 is prepared as follows: S01: 50 parts of diformic acid are mixed evenly with 10 parts of alkyl diacid, 15 parts of olefin diacid, 15 parts of alkyl glycol and 10 parts of trimethylolpropane, reacted at 80°C for 1.5 hours, then heated to 250°C and heated at 250°C for 10 hours to obtain a polyester solution.

[0080] S02: 226g of lysine diisocyanate and 450g of N,N-diethylethanolamine were mixed, stirred, heated to 60°C, and vacuumed to -0.095MPa for reaction for 30min, then heated to 80°C for reaction for 2h to obtain a polyurethane prepolymer. 145g of β-hydroxyethyl acrylate was added to cap the polyurethane prepolymer, and the reaction was carried out for 2h to obtain a polyurethane crosslinker.

[0081] 12g of octylphenol polyoxyethylene ether, 6g of sodium disproportionated rosin acid, 280g of water and 2.5g of sodium bicarbonate were mixed and stirred vigorously to fully dissolve to obtain an emulsion, and then 360g of ethyl acrylate, 515g of ethyl 2-methacrylate and 17g of polyurethane cross-linking agent were stirred evenly to obtain a monomer solution, and the monomer solution and potassium persulfate solution (containing 5g of potassium persulfate and 130g of water) were slowly added to the emulsion at 80°C and stirred for reaction for 3h; after the reaction was completed, the temperature was cooled to room temperature, the pH was adjusted to 7-8 with ammonia water, and the material was filtered to obtain an aqueous polyurethane modified acrylate emulsion.

[0082] S03: Add the polyester solution into the aqueous polyurethane modified acrylate emulsion at a mass ratio of 1:2, stirring at high speed while adding, to obtain a primer solution.

[0083] The performance parameters shown in the various embodiments of the present invention and the comparative examples are measured according to the following methods.

[0084] Adhesion test method: Use the hundred grid method to test, and divide it into 0B-5B according to the severity of ink shedding.

[0085] The properties of the online coated polyester films prepared in the embodiments of the present invention and the comparative examples are shown in Table 1.

[0086] Table 1 Adhesion of UV ink A Adhesion of UV ink B UV ink C adhesion UV ink D adhesion Remark Example 1 5B 5B 5B 5B Example 2 5B 5B 5B 5B Example 3 5B 5B 5B 5B Example 4 5B 5B 5B 5B Example 5 5B 5B 5B 5B Example 6 5B 5B 5B 5B Comparative Example 1 2B 5B 5B 3B Comparative Example 2 5B 1B 5B 3B Comparative Example 3 5B 5B 2B 2B Comparative Example 4 4B 2B 1B 4B Comparative Example 5 2B 3B 1B 4B Comparative Example 6 1B 2B 3B 3B Comparative Example 7 / / / / The primer solution precipitates and cannot be dispersed evenly Comparative Example 8 4B 4B 3B 3B Comparative Example 9 1B 4B 2B 2B Comparative Example 10 0B 4B 4B 1B Comparative Example 11 3B 1B 3B 3B Comparative Example 12 3B 2B 2B 1B Comparative Example 13 3B 2B 3B 2B Comparative Example 14 1B 3B 4B 3B It can be seen from the above data that the online coated polyester film prepared in each embodiment of the present invention has the highest value of 5B in terms of adhesion performance to different types of UV inks. By introducing a mixed coating of water-based polypropylene, water-based polyester and water-based polyurethane on the surface of the polyester film base film, the characteristics of polypropylene, polyester and polyurethane, as well as the synergistic effect between the components, the prepared online coated polyester film has excellent adhesion performance to different types of UV inks.

[0087] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. An online coating polyester film, characterized in that, The polyester film comprises a base film and a primer layer disposed on at least one side of the base film; The primer layer is obtained by coating a primer liquid; The primer solution is prepared as follows: S01: preparing a water-based acrylic emulsion using acrylic acid, an initiator, a dispersant and water as raw materials; S02: using dicarboxylic acid, alkyl diacid, olefin diacid, alkyl glycol and trimethylolpropane as raw materials to prepare a polyester solution; S03: preparing a polyurethane prepolymer using oligomer diol, catalyst, diisocyanate compound, hydrophilic monomer and hydroxide as raw materials; S04: adding the polyester solution and the polyurethane prepolymer into the aqueous acrylic solution to obtain a primer solution.

2. The online coating polyester film according to claim 1, characterized in that The mass ratio of the acrylic acid solution, the polyester solution and the polyurethane prepolymer is (0.5-3):(0.5-3):

1.

3. The online coating polyester film according to claim 1, characterized in that The mass ratio of the dicarboxylic acid, alkyl diacid, olefin diacid, alkyl glycol and trimethylolpropane in step S02 is (20-50):(5-10):(10-30):(10-30):(5-10).

4. The online coating polyester film according to claim 1, characterized in that The mass ratio of the oligomer diol, catalyst, diisocyanate compound and hydrophilic monomer in step S03 is (10-50):(2-9):(10-40):(2-9).

5. The online coating polyester film according to claim 3, characterized in that: The alkyl diacid is selected from at least one of oxalic acid, malonic acid, succinic acid, glutaric acid and adipic acid.

6. The in-line coated polyester film according to claim 3, characterized in that: The olefin diacid is selected from at least one of fumaric acid, maleic acid and propylene acid.

7. The in-line coated polyester film according to claim 3, characterized in that The alkyl glycol is selected from at least one of neopentyl glycol, hexylene glycol, propylene glycol and butanediol.

8. The in-line coated polyester film according to claim 4, characterized in that The oligomer diol is selected from at least one of polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polycaprolactone diol, polycarbonate diol, polyoxyethylene-polyoxypropylene-polyoxyethylene glycol, polyethylene adipate diol, polybutylene adipate diol, polyethylene terephthalate diol, polybutylene terephthalate diol, α,ω-dihydroxy polydimethylsiloxane, dihydroxy polydiphenylsiloxane, and dihydroxy polytrifluoropropylmethylsiloxane.

9. The in-line coated polyester film according to claim 4, characterized in that The diisocyanate compound is at least one selected from 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, isophorone diisocyanate, diphenylmethane 4,4-diisocyanate, methylcyclohexyl diisocyanate, and 2,2,4-trimethylhexane diisocyanate.

10. A method for preparing an online coated polyester film according to any one of claims 1 to 9, characterized in that: The following steps are involved: After the primer liquid is stirred evenly, it is coated on a single surface of the longitudinal stretching sheet of the base film, and then enters the transverse stretching area for stretching. Finally, after shaping, cooling and winding, an online coated polyester film is obtained.