A low-viscosity and low-climbing polyurethane optical protective film and preparation method thereof

Abstract

The present invention relates to the technical field of protective films, and specifically to a low-viscosity and low-climbing polyurethane optical protective film and a preparation method thereof. The present invention introduces a fluorine-containing segment and a siloxane segment by a mercapto-ene click reaction between a double-bond hyperbranched polyester and 1H, 1H, 2H, 2H-perfluorodecanethiol and a mercapto-containing organosilicon to obtain a modified hyperbranched polyester; then, the modified hyperbranched polyester is introduced into polyurethane by a grafting modification method to obtain a polyurethane adhesive; the polyurethane adhesive is coated on the surface of a substrate, and then compounded with a release film, and after ripening, a polyurethane optical protective film is obtained. The polyurethane optical protective film prepared by the present invention has excellent low viscosity and low climbing performance, can effectively protect the surface of optical devices from pollution and damage, and improve its service life and stability.

Description

Technical Field

[0001] The invention relates to the technical field of protective films, in particular to a low-viscosity and low-climbing polyurethane optical protective film and a preparation method thereof. Background Art

[0002] With the widespread application of optical electronic devices, the demand for optical protective films is increasing. In this regard, polyurethane, as an excellent adhesive, is widely used in the preparation of optical protective films due to its excellent mechanical properties, weather resistance and optical properties.

[0003] However, the high viscosity of traditional polyurethane optical protective films makes it difficult to achieve uniform coating during the coating process, and easily forms bubbles and uneven film thickness, affecting the optical performance and appearance quality; during the preparation process, traditional polyurethane optical protective films are prone to climbing phenomenon, that is, as time goes by, the viscosity of the protective film gradually increases, making it difficult to completely tear off the film layer, affecting the optical display effect and service life.

[0004] Therefore, we propose a low-viscosity and low-climbing polyurethane optical protective film and a preparation method thereof. Summary of the invention

[0005] The object of the present invention is to provide a low-viscosity and low-climbing polyurethane optical protective film and a preparation method thereof, so as to solve the problems raised in the above-mentioned background technology.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] A method for preparing a low-viscosity and low-climbing polyurethane optical protective film comprises the following steps:

[0008] Step S1: uniformly mix the modified polyol, polyether polyol and antioxidant, perform vacuum dehydration at 110-120° C. for 2-3 hours, cool to 80-90° C., add isophorone diisocyanate and dibutyltin dilaurate under nitrogen protection, mix uniformly, react for 3-5 hours, add 2,2-dihydroxymethylbutyric acid, modified hyperbranched polyester and acetone, and react for 3-5 hours; cool to 30-40° C., add triethylamine for neutralization, add deionized water for emulsification, remove the solvent acetone by vacuum, and obtain an aqueous polyurethane emulsion; add a defoamer and a leveling agent to the aqueous polyurethane emulsion and mix uniformly to obtain a polyurethane adhesive;

[0009] Step S2: coating the polyurethane adhesive prepared in step S1 on the surface of the substrate, drying at 100-110° C. for 2-3 minutes to form a polyurethane adhesive layer; then compounding with a release film, and ripening at 40-60° C. for 24-72 hours to obtain a polyurethane optical protective film.

[0010] Furthermore, in step S1, the polyurethane adhesive includes the following components by weight: 40-50 parts of modified polyol, 10-15 parts of polyether polyol, 70-90 parts of isophorone diisocyanate, 1-3 parts of dibutyltin dilaurate, 2-4 parts of 2,2-dihydroxymethylbutyric acid, 5-15 parts of modified hyperbranched polyester, 0.2-0.5 parts of triethylamine, 20-40 parts of deionized water, 0.1-0.2 parts of defoaming agent, 0.1-0.3 parts of leveling agent, and 0.1-0.4 parts of antioxidant.

[0011] Furthermore, the preparation method of the modified polyol is as follows:

[0012] Under nitrogen protection, itaconic acid, succinic acid, ethylene glycol, isosorbide, hydroquinone and tetrabutyl titanate are mixed evenly, reacted at 160-170°C for 2-3h, the vacuum degree of the system is controlled to be 0.09MPa, reacted at 160-170°C for 5-7h, cooled to room temperature, purified and dried to obtain a double bond-containing polyester; the double bond-containing polyester, 1-thioglycerol and a photoinitiator are mixed evenly, and after ultraviolet light irradiation, a modified polyol is obtained.

[0013] In the above technical scheme, bio-based monomers such as itaconic acid, succinic acid, ethylene glycol and isosorbide are used as raw materials to prepare double-bond polyesters by melt polycondensation; then, the double-bond polyesters are reacted with 1-thioglycerol to undergo a thiol-ene click reaction to further introduce hydroxyl groups to obtain modified polyols.

[0014] Furthermore, the modified polyol includes the following components by weight: 11-13 parts of itaconic acid, 3-5 parts of succinic acid, 12-14 parts of ethylene glycol, 4-8 parts of isosorbide, 0.01-0.03 parts of hydroquinone, 0.01-0.03 parts of tetrabutyl titanate, 10-15 parts of 1-thioglycerol, and 0.4-0.8 parts of photoinitiator.

[0015] Furthermore, the preparation method of the modified hyperbranched polyester is as follows:

[0016] Step (1): uniformly mix trimethylolpropane, 2,2-dimethylolpropionic acid and N,N-dimethylformamide, add a mixed solution of N,N-dicyclohexylcarbodiimide and N,N-dimethylformamide under ice bath conditions, stir to react for 4-6 hours, and obtain a terminal hydroxyl hyperbranched polyester after centrifugation, rotary evaporation and drying;

[0017] Step (2): uniformly mixing isophorone diisocyanate, 3-phenylprop-2-en-1-ol and dibutyltin dilaurate, and reacting at 45-55° C. for 5-7 hours to obtain a double-bond isocyanate compound; uniformly mixing the double-bond isocyanate compound and the terminal hydroxyl hyperbranched polyester, adding dibutyltin dilaurate, and reacting at 45-55° C. for 6-8 hours to obtain a double-bond hyperbranched polyester;

[0018] Step (3): Under nitrogen protection, 3-mercaptopropylmethyldimethoxysilane, deionized water and isopropanol are mixed evenly, the temperature is raised to 60-70° C., hydroxy silicone oil and tetramethylammonium hydroxide are added and mixed evenly, the mixture is reacted for 4-6 hours, and the mixture is distilled under reduced pressure to obtain a mercapto-containing organosilicon;

[0019] Step (4): uniformly mix the double-bond-containing hyperbranched polyester, 1H,1H,2H,2H-perfluorodecanethiol and mercapto-containing organosilicon, add a photoinitiator, and irradiate with ultraviolet light to obtain a modified hyperbranched polyester.

[0020] In the above technical scheme, step (1) uses trimethylolpropane as a core molecule, 2,2-dimethylpropionic acid as a polymerization monomer, N,N-dicyclohexylcarbodiimide as a dehydrating agent, and N,N-dimethylformamide as a solvent to prepare a terminal hydroxyl hyperbranched polyester; step (2) uses isophorone diisocyanate and 3-phenylprop-2-ene-1-ol to react, introduces a rigid benzene ring structure and a double bond, generates a double bond-containing isocyanate compound, and further reacts with the terminal hydroxyl hyperbranched polyester. reaction to obtain a double-bond hyperbranched polyester; step (3) using 3-mercaptopropylmethyldimethoxysilane to hydrolyze and then dehydrate and condense with hydroxy silicone oil to introduce hydroxyl groups to obtain a mercapto-containing silicone; step (4) introducing fluorine-containing segments and siloxane segments through a mercapto-ene click reaction between the double-bond hyperbranched polyester and 1H,1H,2H,2H-perfluorodecyl mercaptan and the mercapto-containing silicone, thereby reducing the polarity and surface energy of the hyperbranched polyester, thereby effectively reducing the adhesion climbing phenomenon of the adhesive layer.

[0021] Furthermore, in the step (1), the mass ratio of trimethylolpropane, 2,2-dimethylolpropionic acid and N,N-dimethylformamide is 1:(8-10):(6-8), the mass of N,N-dicyclohexylcarbodiimide is 2.5-3.0 times the mass of trimethylolpropane, and the mass of N,N-dimethylformamide is 2-3 times the mass of N,N-dicyclohexylcarbodiimide.

[0022] Furthermore, in the step (2), the mass ratio of isophorone diisocyanate, 3-phenylprop-2-en-1-ol and dibutyltin dilaurate is 1:(1.1-1.3):(0.01-0.03); the mass ratio of the double-bond isocyanate compound, the terminal hydroxyl hyperbranched polyester and dibutyltin dilaurate is 1:(0.5-0.8):(0.01-0.03).

[0023] Furthermore, in step (3), the mass ratio of 3-mercaptopropylmethyldimethoxysilane, deionized water, isopropanol, hydroxy silicone oil and tetramethylammonium hydroxide is 1:(2-3):(7-8):(65-66):(1.2-1.4).

[0024] Furthermore, in the step (4), the mass ratio of the double-bond hyperbranched polyester, 1H,1H,2H,2H-perfluorodecanethiol, mercapto-containing silicone and photoinitiator is 1:(1-2):(0.5-1):(0.3-0.5).

[0025] Furthermore, the photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0026] Furthermore, the process conditions of the ultraviolet irradiation are: irradiation with 360-400nm ultraviolet rays for 30-40min, irradiation intensity of 20-25mW / cm 2 .

[0027] Furthermore, in step S1, the antioxidant is pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxy)phenylpropionate.

[0028] Furthermore, in step S2, the mass of acetone is 12-15 times the mass of the modified hyperbranched polyester.

[0029] Furthermore, in step S2, the substrate is a PET film with a thickness of 25-125 μm.

[0030] Furthermore, in step S2, the thickness of the polyurethane adhesive layer is 3-15 μm.

[0031] Furthermore, in step S2, the compounding pressure is 0.4-0.5 MPa.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. A low-viscosity and low-climbing polyurethane optical protective film and a preparation method thereof of the present invention, using bio-based monomers such as itaconic acid, succinic acid, ethylene glycol and isosorbide as raw materials, preparing a double-bond polyester by melt polycondensation; then, a thiol-ene click reaction is carried out between the double-bond polyester and 1-thioglycerol to further introduce hydroxyl groups to prepare a modified polyol, thereby improving the initial adhesion of the adhesive and the adhesion after wet-heat aging, and enhancing the adhesion and durability of the optical protective film; by compounding the modified polyol and the polyether polyol, the viscosity of the adhesive is reduced, the leveling and coating properties during the production process are ensured, and the performance of the adhesive is optimized.

[0034] 2. The present invention discloses a low-viscosity and low-climbing polyurethane optical protective film and a preparation method thereof. A hydroxyl-containing modified hyperbranched polyester is obtained by introducing fluorine-containing segments and siloxane segments through a thiol-ene click reaction between a double-bond hyperbranched polyester and 1H,1H,2H,2H-perfluorodecanethiol and a thiol-containing organosilicon. The hyperbranched structure and the fluorine-containing segments and the siloxane segments are then introduced into a polyurethane adhesive through a grafting modification method, thereby reducing the polarity and surface energy of the polyurethane adhesive layer, and effectively reducing the climbing of the adhesion of the adhesive layer. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] In this embodiment, polyether polyol: brand CP450, sourced from Dow Chemical; leveling agent: model KYC-615; defoaming agent: model BYK-028; PET film: polyethylene terephthalate film, thickness 50 μm, sourced from Dongguan Dongwei Electronic Materials Co., Ltd.; release film: PET release film, brand ZQLXKJD, sourced from Dongguan Zhanqian Electronic Materials Co., Ltd.

[0037] In the following examples and comparative examples, 1 part is equal to 10 g.

[0038] Example 1: A method for preparing a low-viscosity and low-climbing polyurethane optical protective film, comprising the following process:

[0039] Step S1: 40 parts of modified polyol, 10 parts of polyether polyol and 0.1 parts of antioxidant are mixed evenly, vacuum dehydrated at 110° C. for 2 hours, cooled to 80° C., and under nitrogen protection, 70 parts of isophorone diisocyanate and 1 part of dibutyltin dilaurate are added and mixed evenly, reacted for 3 hours, and 2 parts of 2,2-dihydroxymethylbutyric acid, 5 parts of modified hyperbranched polyester and 60 parts of acetone are added and reacted for 3 hours; cooled to 30° C., 0.2 parts of triethylamine are added for neutralization, and 20 parts of deionized water are added for emulsification, and the solvent acetone is removed by vacuum to obtain an aqueous polyurethane emulsion; 0.1 parts of a defoaming agent and 0.1 parts of a leveling agent are added to the aqueous polyurethane emulsion and mixed evenly to obtain a polyurethane adhesive;

[0040] Step S2: coating the polyurethane adhesive prepared in step S1 on the surface of the substrate, drying at 100° C. for 3 min to form a polyurethane adhesive layer; then laminating with a release film (laminating pressure of 0.4 MPa), and aging at 40° C. for 72 h to obtain a polyurethane optical protective film;

[0041] The preparation method of modified polyol is as follows:

[0042] Under nitrogen protection, 11 parts of itaconic acid, 3 parts of succinic acid, 12 parts of ethylene glycol, 4 parts of isosorbide, 0.01 parts of hydroquinone and 0.01 parts of tetrabutyl titanate were mixed evenly, reacted at 160°C for 2 hours, the vacuum degree of the system was controlled to be 0.09 MPa, reacted at 160°C for 5 hours, cooled to room temperature, purified and dried to obtain a polyester containing a double bond; the polyester containing a double bond was mixed evenly with 10 parts of 1-thioglycerol and 0.4 photoinitiator, and irradiated with ultraviolet light (irradiated with 360nm ultraviolet light for 30 minutes, irradiation intensity 25mW / cm 2 ), to obtain modified polyol;

[0043] The preparation method of modified hyperbranched polyester is as follows:

[0044] Step (1): 5 parts of trimethylolpropane, 40 parts of 2,2-dimethylolpropionic acid and 30 parts of N,N-dimethylformamide are mixed evenly, and a mixed solution of 7.5 parts of N,N-dicyclohexylcarbodiimide and 10 parts of N,N-dimethylformamide is added under ice bath conditions, and the mixture is stirred for reaction for 4 hours. After centrifugation, rotary evaporation and drying, a terminal hydroxyl hyperbranched polyester is obtained;

[0045] Step (2): 10 parts of isophorone diisocyanate, 11 parts of 3-phenylprop-2-en-1-ol and 0.1 parts of dibutyltin dilaurate are mixed evenly, and the mixture is reacted at 45°C for 5 hours to obtain a double bond-containing isocyanate compound; 10 parts of the double bond-containing isocyanate compound and 5 parts of a terminal hydroxyl hyperbranched polyester are mixed evenly, 0.1 parts of dibutyltin dilaurate are added, and the mixture is reacted at 45°C for 6 hours to obtain a double bond-containing hyperbranched polyester;

[0046] Step (3): Under nitrogen protection, 2.5 parts of 3-mercaptopropylmethyldimethoxysilane, 5 parts of deionized water and 17.5 parts of isopropanol were mixed evenly, the temperature was raised to 60°C, 162.5 parts of hydroxy silicone oil and 3 parts of tetramethylammonium hydroxide were added and mixed evenly, the mixture was reacted for 4 hours, and the mixture was subjected to reduced pressure distillation to obtain a mercapto-containing organosilicon;

[0047] Step (4): 5 parts of double-bond hyperbranched polyester, 5 parts of 1H,1H,2H,2H-perfluorodecanethiol and 2.5 parts of mercapto-containing organosilicon are mixed evenly, 1.5 parts of photoinitiator are added, and after ultraviolet light irradiation (360nm ultraviolet light irradiation for 30 minutes, irradiation intensity 25mW / cm 2 ), to obtain modified hyperbranched polyester.

[0048] Example 2: A method for preparing a low-viscosity and low-climbing polyurethane optical protective film, comprising the following process:

[0049] Step S1: 45 parts of modified polyol, 12 parts of polyether polyol and 0.3 parts of antioxidant are mixed evenly, vacuum dehydrated at 115°C for 2.5 hours, cooled to 85°C, and under nitrogen protection, 80 parts of isophorone diisocyanate and 2 parts of dibutyltin dilaurate are added and mixed evenly, reacted for 4 hours, 3 parts of 2,2-dihydroxymethylbutyric acid, 10 parts of modified hyperbranched polyester and 130 parts of acetone are added, and reacted for 4 hours; cooled to 35°C, 0.4 parts of triethylamine are added for neutralization, and 30 parts of deionized water are added for emulsification, and the solvent acetone is removed by vacuum to obtain an aqueous polyurethane emulsion; 0.15 parts of a defoamer and 0.2 parts of a leveling agent are added to the aqueous polyurethane emulsion and mixed evenly to obtain a polyurethane adhesive;

[0050] Step S2: coating the polyurethane adhesive prepared in step S1 on the surface of the substrate, drying at 105° C. for 2.5 min to form a polyurethane adhesive layer; then laminating with a release film (laminating pressure of 0.45 MPa), and aging at 50° C. for 48 h to obtain a polyurethane optical protective film;

[0051] The preparation method of modified polyol is as follows:

[0052] Under nitrogen protection, 12 parts of itaconic acid, 4 parts of succinic acid, 13 parts of ethylene glycol, 6 parts of isosorbide, 0.02 parts of hydroquinone and 0.02 parts of tetrabutyl titanate were mixed evenly, reacted at 165°C for 2.5 hours, the vacuum degree of the system was controlled to be 0.09 MPa, reacted at 165°C for 6 hours, cooled to room temperature, purified and dried to obtain a polyester containing a double bond; the polyester containing a double bond was mixed evenly with 14 parts of 1-thioglycerol and 0.6 photoinitiator, and irradiated with ultraviolet light (irradiated with 380nm ultraviolet light for 35 minutes, irradiation intensity 22mW / cm 2 ), to obtain modified polyol;

[0053] The preparation method of modified hyperbranched polyester is as follows:

[0054] Step (1): 10 parts of trimethylolpropane, 90 parts of 2,2-dimethylolpropionic acid and 60 parts of N,N-dimethylformamide are mixed evenly, and a mixed solution of 28 parts of N,N-dicyclohexylcarbodiimide and 70 parts of N,N-dimethylformamide is added under ice bath conditions, and the mixture is stirred for reaction for 5 hours. After centrifugation, rotary evaporation and drying, a terminal hydroxyl hyperbranched polyester is obtained;

[0055] Step (2): 15 parts of isophorone diisocyanate, 18 parts of 3-phenylprop-2-en-1-ol and 0.3 parts of dibutyltin dilaurate are mixed evenly, and the mixture is reacted at 50°C for 6 hours to obtain a double bond-containing isocyanate compound; 15 parts of the double bond-containing isocyanate compound and 10 parts of a terminal hydroxyl hyperbranched polyester are mixed evenly, 0.3 parts of dibutyltin dilaurate are added, and the mixture is reacted at 50°C for 7 hours to obtain a double bond-containing hyperbranched polyester;

[0056] Step (3): Under nitrogen protection, 8 parts of 3-mercaptopropylmethyldimethoxysilane, 20 parts of deionized water and 60 parts of isopropanol were mixed evenly, the temperature was raised to 65°C, 524 parts of hydroxy silicone oil and 10.4 parts of tetramethylammonium hydroxide were added and mixed evenly, the mixture was reacted for 5 hours, and the mixture was subjected to reduced pressure distillation to obtain a mercapto-containing organosilicon;

[0057] Step (4): 10 parts of double-bond hyperbranched polyester, 15 parts of 1H,1H,2H,2H-perfluorodecanethiol and 8 parts of mercapto-containing organosilicon were mixed evenly, 4 parts of photoinitiator were added, and after ultraviolet light irradiation (380nm ultraviolet light irradiation for 35min, irradiation intensity 22mW / cm 2 ), to obtain modified hyperbranched polyester.

[0058] Example 3: A method for preparing a low-viscosity and low-climbing polyurethane optical protective film, comprising the following process:

[0059] Step S1: 50 parts of modified polyol, 15 parts of polyether polyol and 0.4 parts of antioxidant are mixed evenly, vacuum dehydrated at 120°C for 3 hours, cooled to 90°C, and under nitrogen protection, 90 parts of isophorone diisocyanate and 3 parts of dibutyltin dilaurate are added and mixed evenly, reacted for 5 hours, 4 parts of 2,2-dihydroxymethylbutyric acid, 15 parts of modified hyperbranched polyester and 225 parts of acetone are added, and reacted for 4 hours; cooled to 40°C, 0.5 parts of triethylamine are added for neutralization, and 40 parts of deionized water are added for emulsification, and the solvent acetone is removed by vacuum to obtain an aqueous polyurethane emulsion; 0.2 parts of a defoamer and 0.3 parts of a leveling agent are added to the aqueous polyurethane emulsion and mixed evenly to obtain a polyurethane adhesive;

[0060] Step S2: coating the polyurethane adhesive prepared in step S1 on the surface of the substrate, drying at 110° C. for 2 min to form a polyurethane adhesive layer; then laminating with a release film (laminating pressure of 0.5 MPa), and aging at 60° C. for 24 h to obtain a polyurethane optical protective film;

[0061] The preparation method of modified polyol is as follows:

[0062] Under nitrogen protection, 13 parts of itaconic acid, 5 parts of succinic acid, 14 parts of ethylene glycol, 8 parts of isosorbide, 0.03 parts of hydroquinone and 0.03 parts of tetrabutyl titanate were mixed evenly, reacted at 170°C for 3 hours, the vacuum degree of the system was controlled to be 0.09 MPa, reacted at 170°C for 7 hours, cooled to room temperature, purified and dried to obtain a polyester containing a double bond; the polyester containing a double bond was mixed evenly with 15 parts of 1-thioglycerol and 0.8 photoinitiator, and irradiated with ultraviolet light (irradiated with 400nm ultraviolet light for 40min, irradiation intensity 20mW / cm 2 ), to obtain modified polyol;

[0063] The preparation method of modified hyperbranched polyester is as follows:

[0064] Step (1): 15 parts of trimethylolpropane, 150 parts of 2,2-dimethylolpropionic acid and 120 parts of N,N-dimethylformamide are mixed uniformly, and a mixed solution of 45 parts of N,N-dicyclohexylcarbodiimide and 135 parts of N,N-dimethylformamide is added under ice bath conditions, and the mixture is stirred for reaction for 6 hours. After centrifugation, rotary evaporation and drying, a terminal hydroxyl hyperbranched polyester is obtained;

[0065] Step (2): 18.75 parts of isophorone diisocyanate, 24 parts of 3-phenylprop-2-en-1-ol and 0.56 parts of dibutyltin dilaurate are mixed evenly, and the mixture is reacted at 55° C. for 7 hours to obtain a double bond-containing isocyanate compound; 18.75 parts of the double bond-containing isocyanate compound and 15 parts of a terminal hydroxyl hyperbranched polyester are mixed evenly, 0.56 parts of dibutyltin dilaurate are added, and the mixture is reacted at 55° C. for 8 hours to obtain a double bond-containing hyperbranched polyester;

[0066] Step (3): Under nitrogen protection, 15 parts of 3-mercaptopropylmethyldimethoxysilane, 45 parts of deionized water and 120 parts of isopropanol were mixed evenly, the temperature was raised to 70°C, 990 parts of hydroxy silicone oil and 21 parts of tetramethylammonium hydroxide were added and mixed evenly, the mixture was reacted for 6 hours, and the mixture was subjected to reduced pressure distillation to obtain a mercapto-containing organosilicon;

[0067] Step (4): 15 parts of double-bond hyperbranched polyester, 30 parts of 1H,1H,2H,2H-perfluorodecanethiol and 15 parts of mercapto-containing organosilicon were mixed evenly, 7.5 parts of photoinitiator were added, and after ultraviolet light irradiation (400nm ultraviolet light irradiation for 40min, irradiation intensity 20mW / cm 2 ), to obtain modified hyperbranched polyester.

[0068] Comparative Example 1: A method for preparing a low-viscosity and low-climbing polyurethane optical protective film, comprising the following processes:

[0069] Compared with Example 2, no polyether polyol was added in Comparative Example 1, and other steps were the same as those in Example 2.

[0070] Comparative Example 2: A method for preparing a low-viscosity and low-climbing polyurethane optical protective film, comprising the following process:

[0071] Compared with Example 2, in Comparative Example 2, the modified hyperbranched polyester is replaced with a hyperbranched polyester of the same mass, and the other steps are the same as those of Example 2.

[0072] Comparative Example 3: A method for preparing a low-viscosity and low-climbing polyurethane optical protective film, comprising the following processes:

[0073] Compared with Example 2, Comparative Example 3 adds 1 part of modified hyperbranched polyester, and the other steps are the same as Example 2.

[0074] Comparative Example 4: A method for preparing a low-viscosity and low-climbing polyurethane optical protective film, comprising the following processes:

[0075] The preparation method of modified hyperbranched polyester is as follows:

[0076] Step (1): 10 parts of trimethylolpropane, 90 parts of 2,2-dimethylolpropionic acid and 60 parts of N,N-dimethylformamide are mixed evenly, and a mixed solution of 28 parts of N,N-dicyclohexylcarbodiimide and 70 parts of N,N-dimethylformamide is added under ice bath conditions, and the mixture is stirred for reaction for 5 hours. After centrifugation, rotary evaporation and drying, a terminal hydroxyl hyperbranched polyester is obtained;

[0077] Step (2): 15 parts of isophorone diisocyanate, 18 parts of 3-phenylprop-2-en-1-ol and 0.3 parts of dibutyltin dilaurate are mixed evenly, and the mixture is reacted at 50°C for 6 hours to obtain a double bond-containing isocyanate compound; 15 parts of the double bond-containing isocyanate compound and 10 parts of a terminal hydroxyl hyperbranched polyester are mixed evenly, 0.3 parts of dibutyltin dilaurate are added, and the mixture is reacted at 50°C for 6 hours to obtain a double bond-containing hyperbranched polyester;

[0078] Step (3): 10 parts of double-bond hyperbranched polyester, 15 parts of 1H,1H,2H,2H-perfluorodecanethiol, and 4 parts of photoinitiator were added, and then irradiated with ultraviolet light (380nm ultraviolet light for 35 minutes, irradiation intensity 22mW / cm 2 ), to obtain a modified hyperbranched polyester;

[0079] Compared with Example 2, Comparative Example 4 does not add mercapto-containing silicone; other steps are the same as Example 2.

[0080] Experiment: The polyurethane optical protective films obtained in Examples 1-3 and Comparative Examples 1-4 were taken to prepare samples, and their properties were tested and the test results were recorded:

[0081] The peeling force was measured according to ASTM D-3330. The sample size was 2.5 cm × 10 cm. The release film was removed and the sample was attached to the glass surface. An electronic universal testing machine was used to perform the peeling test at an angle of 180° and a tensile speed of 300 mm / min.

[0082] The heat-resistant adhesion was measured with reference to ASTM D-3330. The sample size was 2.5 cm × 10 cm. The release film was removed and adhered to the glass surface. The sample was placed in a 150°C oven and heated for 1 hour. After cooling for 2 hours, an electronic universal testing machine was used to perform a peeling test at an angle of 180° and a tensile speed of 300 mm / min to evaluate the increase in the peeling force after long-term adhesion between the protective film and the adhered object.

[0083] Test Results

[0084]

[0085] According to the data in the above table, we can clearly draw the following conclusions:

[0086] Compared with Examples 1-3, the peeling force of the product obtained in Comparative Example 1 is increased and the heat-resistant adhesive force is higher, indicating that the performance of the adhesive can be improved by adding polyether polyols and compounding with modified polyols.

[0087] Compared with Examples 1-3, the peeling force of the products obtained in Comparative Examples 2 and 3 is increased, and the heat-resistant adhesion climb is higher. It can be seen that compared with the hyperbranched polyester, the modified hyperbranched polyester prepared by the present invention has a better viscosity reduction effect. Reducing the addition amount of the modified hyperbranched polyester will lead to an increase in the viscosity and climb of the polyurethane adhesive.

[0088] Compared with Examples 1-3, the peeling force of the product obtained in Comparative Example 4 is increased and the heat-resistant adhesive force is higher, indicating that the introduction of siloxane segments in the preparation process of the modified hyperbranched polyester can further reduce the increase in the adhesive force of the adhesive layer.

[0089] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process method article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process method article or device.

[0090] 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 low-viscosity and low-climbing polyurethane optical protective film, characterized in that: The steps include: Step S1: uniformly mix the modified polyol, polyether polyol and antioxidant, dehydrate under vacuum at 110-120° C. for 2-3 hours, cool to 80-90° C., add isophorone diisocyanate and dibutyltin dilaurate under nitrogen protection, mix uniformly, react for 3-5 hours, add 2,2-dihydroxymethylbutyric acid, modified hyperbranched polyester and acetone, react for 3-5 hours; cool to 30-40° C., add triethylamine for neutralization, add deionized water for emulsification, remove the solvent acetone by vacuum, and obtain an aqueous polyurethane emulsion; add a defoamer and a leveling agent to the aqueous polyurethane emulsion and mix uniformly to obtain a polyurethane adhesive; Step S2: coating the polyurethane adhesive prepared in step S1 on the surface of the substrate, drying at 100-110° C. for 2-3 min to form a polyurethane adhesive layer; then compounding with a release film, and aging at 40-60° C. for 24-72 h to obtain a polyurethane optical protective film; The preparation method of the modified polyol is as follows: Under nitrogen protection, itaconic acid, succinic acid, ethylene glycol, isosorbide, hydroquinone and tetrabutyl titanate are mixed evenly, reacted at 160-170°C for 2-3h, the vacuum degree of the system is controlled to be 0.09MPa, reacted at 160-170°C for 5-7h, cooled to room temperature, purified and dried to obtain a polyester containing a double bond; the polyester containing a double bond is mixed evenly with 1-thioglycerol and a photoinitiator, and irradiated with ultraviolet light to obtain a modified polyol; In the step S1, the polyurethane adhesive comprises the following components by weight: 40-50 parts of modified polyol, 10-15 parts of polyether polyol, 70-90 parts of isophorone diisocyanate, 1-3 parts of dibutyltin dilaurate, 2-4 parts of 2,2-dihydroxymethylbutyric acid, 5-15 parts of modified hyperbranched polyester, 0.2-0.5 parts of triethylamine, 20-40 parts of deionized water, 0.1-0.2 parts of defoaming agent, 0.1-0.3 parts of leveling agent, and 0.1-0.4 parts of antioxidant; The preparation method of the modified hyperbranched polyester is as follows: Step (1): uniformly mix trimethylolpropane, 2,2-dimethylolpropionic acid and N,N-dimethylformamide, add a mixed solution of N,N-dicyclohexylcarbodiimide and N,N-dimethylformamide under ice bath conditions, stir to react for 4-6 hours, and obtain a terminal hydroxyl hyperbranched polyester after centrifugation, rotary evaporation and drying; Step (2): uniformly mixing isophorone diisocyanate, 3-phenylprop-2-en-1-ol and dibutyltin dilaurate, and reacting at 45-55° C. for 5-7 hours to obtain a double-bond isocyanate compound; uniformly mixing the double-bond isocyanate compound and the terminal hydroxyl hyperbranched polyester, adding dibutyltin dilaurate, and reacting at 45-55° C. for 6-8 hours to obtain a double-bond hyperbranched polyester; Step (3): Under nitrogen protection, 3-mercaptopropylmethyldimethoxysilane, deionized water and isopropanol are mixed evenly, the temperature is raised to 60-70° C., hydroxy silicone oil and tetramethylammonium hydroxide are added and mixed evenly, the mixture is reacted for 4-6 hours, and the mixture is distilled under reduced pressure to obtain a mercapto-containing organosilicon; Step (4): uniformly mix the double-bond-containing hyperbranched polyester, 1H,1H,2H,2H-perfluorodecanethiol and mercapto-containing organosilicon, add a photoinitiator, and irradiate with ultraviolet light to obtain a modified hyperbranched polyester.

2. The method for preparing a low-viscosity and low-climbing polyurethane optical protective film according to claim 1, characterized in that: The modified polyol comprises the following components by weight: 11-13 parts of itaconic acid, 3-5 parts of succinic acid, 12-14 parts of ethylene glycol, 4-8 parts of isosorbide, 0.01-0.03 parts of hydroquinone, 0.01-0.03 parts of tetrabutyl titanate, 10-15 parts of 1-thioglycerol, and 0.4-0.8 parts of a photoinitiator.

3. The method for preparing a low-viscosity and low-climbing polyurethane optical protective film according to claim 1, characterized in that: In the step (1), the mass ratio of trimethylolpropane, 2,2-dimethylolpropionic acid and N,N-dimethylformamide is 1:(8-10):(6-8), the mass of N,N-dicyclohexylcarbodiimide is 2.5-3.0 times the mass of trimethylolpropane, and the mass of N,N-dimethylformamide is 2-3 times the mass of N,N-dicyclohexylcarbodiimide.

4. The method for preparing a low-viscosity and low-climbing polyurethane optical protective film according to claim 1, characterized in that: In the step (4), the mass ratio of the double-bond hyperbranched polyester, 1H,1H,2H,2H-perfluorodecanethiol, mercapto-containing silicone and photoinitiator is 1:(1-2):(0.5-1.0):(0.3-0.5).

5. The method for preparing a low-viscosity and low-climbing polyurethane optical protective film according to claim 1, characterized in that: In the step S2, the substrate is a PET film with a thickness of 25-125 μm.

6. The method for preparing a low-viscosity and low-climbing polyurethane optical protective film according to claim 1, characterized in that: In the step S2, the thickness of the polyurethane adhesive layer is 3-15 μm.

7. A low-viscosity and low-climbing polyurethane optical protective film prepared according to the preparation method according to any one of claims 1 to 6.

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