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CN-122011921-A - Degradable polyurethane composite coating material for light guide plate protective film

CN122011921ACN 122011921 ACN122011921 ACN 122011921ACN-122011921-A

Abstract

The invention relates to the technical field of composite coatings, in particular to a degradable polyurethane composite coating material for a light guide plate protective film, which comprises the following components, by mass, 50-55% of polyurethane prepolymer combination, 26-30.5% of crystallizable polyester soft segment combination, 8-12% of hexamethylene diisocyanate trimer, 3-5% of trimethylolpropane, 1-2% of dibutyltin dilaurate, 1-2% of stannous octoate, 1-2% of polyether modified polydimethylsiloxane and 0.5-1% of polydimethylsiloxane, wherein degradation inhibition in the service life is realized through soft segment crystallization locking, hydrolysis is realized after the soft segment is triggered by composting temperature, the soft segment is melted and unlocked to accelerate discarding, and the high-temperature high-humidity no-residual glue is ensured through an ionization structure, so that the key problems of durability, discarding degradability, difficulty in considering both high temperature and high-humidity easy-residual glue of the degradable polyurethane coating are solved, and a novel degradable composite coating material with optical performance, using stability and environmental friendliness is provided for the light guide plate protective film.

Inventors

  • DU XUEFENG

Assignees

  • 广州市鸿琦升塑料有限公司

Dates

Publication Date
20260512
Application Date
20260331

Claims (8)

  1. 1. A degradable polyurethane composite coating material for a light guide plate protective film is characterized by comprising, by mass, 50-55% of polyurethane prepolymer combination, 26-30.5% of crystallizable polyester soft segment combination, 8-12% of hexamethylene diisocyanate trimer, 3-5% of trimethylolpropane, 1-2% of dibutyltin dilaurate, 1-2% of stannous octoate, 1-2% of polyether modified polydimethylsiloxane and 0.5-1% of polydimethylsiloxane.
  2. 2. The degradable polyurethane composite coating material for the light guide plate protective film according to claim 1, wherein the polyurethane prepolymer composition comprises the following components by mass percent of 45% polycarbonate diol, 35% isophorone diisocyanate, 12% bisphenol A dihydroxyethyl ether, 5% dimethylolpropionic acid and 3% triethylamine.
  3. 3. The degradable polyurethane composite coating material for the light guide plate protective film according to claim 1, wherein the preparation method of the polyurethane prepolymer combination comprises the following steps: A1, placing the polycarbonate diol in a vacuum drying oven, setting the temperature to be 110 ℃, and drying for 4 hours at the vacuum degree of-0.09 MPa, detecting the moisture content by using a moisture tester after drying, controlling the moisture content to be lower than 0.03%, and transferring the obtained dried polycarbonate diol to a dryer for cooling to room temperature for standby; A2, transferring the dried polycarbonate diol into a reaction kettle, wherein the reaction kettle adopts a double-layer stainless steel structure, a heat conduction oil is introduced into an interlayer for temperature control, a stirrer is started, the rotating speed of the stirrer is set to 300rpm, isophorone diisocyanate is added, then high-purity nitrogen is introduced into the reaction kettle, the flow rate of the nitrogen is 5L/min, air in the reaction kettle is replaced for 3 times, the positive pressure protection of the nitrogen is kept, the temperature is raised to 80 ℃ through the heat conduction oil, and the heat preservation reaction is carried out for 2 hours, so that an isocyanate-terminated prepolymer is obtained; A3, adding bisphenol A dihydroxyethyl ether and dihydroxymethyl propionic acid into the isocyanate-terminated prepolymer, continuously reacting for 1.5 hours, controlling the reaction temperature to be 85 ℃ through heat conducting oil in the reaction process, keeping the reaction system heated uniformly, performing gel permeation chromatography test after the reaction is finished, and taking a product with the number average molecular weight of 5000-6000 and the molecular weight distribution index of 1.3-1.5 of the prepolymer to obtain a polyurethane prepolymer containing carboxyl; a4, cooling the carboxyl-containing polyurethane prepolymer to 45 ℃ at a cooling rate of 0.5 ℃ per minute, then adding triethylamine, setting the rotating speed of a stirrer to 400rpm, stirring and neutralizing for 30 minutes, continuing stirring for 15 minutes after the neutralizing is finished, obtaining a polyurethane prepolymer combination, transferring the polyurethane prepolymer combination into a sealed stainless steel storage tank while the polyurethane prepolymer combination is hot, filling nitrogen for protection, maintaining the nitrogen pressure at 0.03MPa, and preserving the polyurethane prepolymer combination at normal temperature and in a dark place.
  4. 4. The degradable polyurethane composite coating material for the light guide plate protective film according to claim 1, wherein the crystallizable polyester soft segment composition comprises, by mass, 45% of caprolactone, 10% of decalactone, 20% of polytetrahydrofuran glycol, 12% of polyethylene glycol, 8% of butanediol, 4.8% of ethylene glycol and 0.2% of stannous octoate.
  5. 5. The degradable polyurethane composite coating material for the light guide plate protective film according to claim 1, wherein the preparation method of the crystallizable polyester soft segment combination comprises the following steps: Adding caprolactone, decalactone, polytetrahydrofuran glycol, polyethylene glycol, butanediol and ethylene glycol into a stainless steel reaction kettle, preparing a double-layer spiral belt type stirrer and a nitrogen inlet and outlet, starting the stirrer, setting the rotating speed of the stirrer to be 200rpm, stirring and mixing for 15min, adding stannous octoate after stirring and mixing are completed, continuing stirring for 10min, then introducing high-purity nitrogen into the reaction kettle, wherein the flow rate of the nitrogen is 8L/min, replacing the air in the kettle for 4 times, and keeping the positive pressure protection of the nitrogen; B2, heating the reaction kettle to 150 ℃ through oil bath, wherein the heating rate is 1.5 ℃ per minute, carrying out heat preservation polymerization for 6 hours, sampling and measuring the conversion rate every 1 hour in the reaction process, and detecting the residual monomer content by adopting a gas chromatography, wherein the reaction is completed when the conversion rate is more than 95%, so as to obtain a blend system of the poly (caprolactone-co-decalactone) copolymer, polytetrahydrofuran glycol, polyethylene glycol, butanediol and ethylene glycol; B3, transferring the blending system into a rotary evaporator after the reaction is finished, setting the water bath temperature to be 110 ℃, the vacuum degree to be-0.09 MPa, evaporating to remove unreacted monomers and low-boiling byproducts, and sampling to perform gel permeation chromatography test after the evaporation is finished for 1.5h, wherein the chromatographic condition is that the mobile phase is tetrahydrofuran, the flow rate is 1.0mL/min, the chromatographic column is STYRAGEL HR and HR4 are connected in series, the detector is a differential refractive detector, the column temperature is 35 ℃, the product with the number average molecular weight of 3000-4000 and the molecular weight distribution index of 1.3-1.5 is taken, and simultaneously, nuclear magnetic resonance hydrogen spectrum is carried out to confirm the copolymerization proportion, and the product with the molar ratio of caprolactone units to decalactone units in the range of 83:17-87:13 is obtained, so as to obtain the crystallizable polyester soft segment combination; and B4, transferring the crystallized polyester soft segment combination into a closed stainless steel storage tank while the combination is hot, charging nitrogen for protection, maintaining the nitrogen pressure at 0.02-0.05MPa, preserving at normal temperature in a dark place, and preheating for 30min in a water bath at 60 ℃ and uniformly stirring before use.
  6. 6. The degradable polyurethane composite coating material for the light guide plate protective film according to claim 1, wherein the content of the dibutyl tin dilaurate is 19%, the viscosity at 25 ℃ is 65 mPas, and the moisture content is less than or equal to 0.1%.
  7. 7. The degradable polyurethane composite coating material for the light guide plate protective film according to claim 1, wherein the stannous octoate has a tin content of 28%, a viscosity of 300 mPa-s at 25 ℃ and a moisture content of less than or equal to 0.2%.
  8. 8. The method for preparing the degradable polyurethane composite coating material for the light guide plate protective film according to claim 1, which is characterized by comprising the following steps: S1, weighing a polyurethane prepolymer combination, a crystallizable polyester soft segment combination and trimethylolpropane, adding the polyurethane prepolymer combination, the crystallizable polyester soft segment combination and the trimethylolpropane into a stainless steel reaction kettle, controlling the temperature of an interlayer of the reaction kettle by passing through heat conduction oil, providing a hinge type stirrer and a nitrogen protection device, starting the stirrer, setting the rotating speed of the stirrer to be 400rpm, heating to 75 ℃ under the protection of nitrogen, heating to 0.8 ℃ per minute, carrying out heat preservation stirring reaction, sampling and measuring the viscosity every 30 minutes in the reaction process, measuring at 75 ℃ by adopting a rotary viscometer, and finishing the reaction when the viscosity reaches 8000-10000 mPa.s; S2, cooling the reaction kettle to 60 ℃ at a cooling rate of 0.5 ℃ per minute, adding hexamethylene diisocyanate trimer, continuously stirring and reacting for 30 minutes, adjusting the stirring rotation speed to 350rpm, controlling the temperature to 60 ℃ in the reaction process, sampling and measuring the NCO content after the reaction is finished, and controlling the NCO content to be within a range of 1.5-2.0%, thus obtaining the polyurethane composite resin; S3, adding dibutyl tin dilaurate, stannous octoate, polyether modified polydimethylsiloxane and polydimethylsiloxane into a reaction kettle, setting the rotating speed of a stirrer to be 500rpm, stirring and mixing for 20min, adopting interlayer circulating water cooling in the stirring process, and controlling the temperature of the materials to be 45 ℃ to obtain polyurethane composite coating mixed solution; S4, transferring the polyurethane composite coating mixed solution into a high-speed dispersing machine, adding a butanone solvent, wherein the mass ratio of the butanone solvent to the polyurethane composite coating mixed solution is 1:1.5, setting the dispersing speed to be 1500rpm, dispersing for 15min, controlling the temperature to be 35 ℃ by adopting interlayer cooling water in the dispersing process to obtain a degradable polyurethane composite coating material, filtering the polyurethane composite coating material by a 200-mesh stainless steel filter screen at the filtering pressure of 0.3MPa, changing the filter screen once every 500kg, transferring the filtered coating material into a closed stainless steel storage tank, refrigerating and preserving at 4 ℃, taking out the coating material and returning to the temperature in a constant-temperature water bath at 25 ℃ for 30min before using, and uniformly stirring.

Description

Degradable polyurethane composite coating material for light guide plate protective film Technical Field The invention relates to the technical field of composite coatings, in particular to a degradable polyurethane composite coating material for a light guide plate protective film. Background In the field of light guide plate protective films, the surface of the light guide plate is very easy to scratch and pollute in the processing, transportation and assembly processes, the traditional protective film usually adopts polyester and polyethylene base materials matched with acrylic pressure-sensitive adhesives, while the basic physical protection requirement can be met, but the protective film taking petroleum base materials as the main body is largely abandoned after use and is difficult to naturally degrade, and becomes an important source of electronic waste pollution, and more troublesome, the existing degradable protective film adopts polylactic acid and polycaprolactone biological base materials, but has the problems of poor ageing resistance, easy adhesive residue in high-temperature and high-humidity environments and insufficient optical transparency at the expense of service performance, and forms the dilemma of mutual elbow pulling between degradability and service performance. The research finds that the structural design of the degradable polyester chain segment and the polyurethane matrix on the molecular scale can effectively break through the technical limitation of the traditional degradable protective film, however, the prior art scheme lacks a molecular structural design capable of controlling the degradation inhibition in the service period and the degradation acceleration in the discarding period, so that the degradable chain segment is slowly hydrolyzed in the use process, the durability of the material is reduced, meanwhile, the interface adhesion force is insufficient in a high-temperature and high-humidity environment, the surface of the light guide plate is polluted by residual glue easily, and the application and popularization of the degradable protective film in precision optical devices are severely restricted. The present invention provides a solution to the above problems. Disclosure of Invention The invention aims to provide a degradable polyurethane composite coating material for a light guide plate protective film, and the prepared light guide plate protective film has good optical performance and long-term use stability, and can be rapidly degraded after being abandoned. The degradable polyurethane composite coating material for the light guide plate protective film comprises, by mass, 50-55% of polyurethane prepolymer combination, 26-30.5% of crystallizable polyester soft segment combination, 8-12% of hexamethylene diisocyanate trimer, 3-5% of trimethylolpropane, 1-2% of dibutyltin dilaurate, 1-2% of stannous octoate, 1-2% of polyether modified polydimethylsiloxane and 0.5-1% of polydimethylsiloxane; further, the polyurethane prepolymer combination consists of 45% of polycarbonate diol, 35% of isophorone diisocyanate, 12% of bisphenol A dihydroxyethyl ether, 5% of dimethylolpropionic acid and 3% of triethylamine in percentage by mass; further, the preparation method of the polyurethane prepolymer combination comprises the following steps: A1, placing the polycarbonate diol in a vacuum drying oven, setting the temperature to be 110 ℃, and drying for 4 hours at the vacuum degree of-0.09 MPa, detecting the moisture content by using a moisture tester after drying, controlling the moisture content to be lower than 0.03%, and transferring the obtained dried polycarbonate diol to a dryer for cooling to room temperature for standby; A2, transferring the dried polycarbonate diol into a reaction kettle, wherein the reaction kettle adopts a double-layer stainless steel structure, a heat conduction oil is introduced into an interlayer for temperature control, a stirrer is started, the rotating speed of the stirrer is set to 300rpm, isophorone diisocyanate is added, then high-purity nitrogen is introduced into the reaction kettle, the flow rate of the nitrogen is 5L/min, air in the reaction kettle is replaced for 3 times, the positive pressure protection of the nitrogen is kept, the temperature is raised to 80 ℃ through the heat conduction oil, and the heat preservation reaction is carried out for 2 hours, so that an isocyanate-terminated prepolymer is obtained; A3, adding bisphenol A dihydroxyethyl ether and dihydroxymethyl propionic acid into the isocyanate-terminated prepolymer, continuously reacting for 1.5 hours, controlling the reaction temperature to be 85 ℃ through heat conducting oil in the reaction process, keeping the reaction system heated uniformly, performing gel permeation chromatography test after the reaction is finished, and taking a product with the number average molecular weight of 5000-6000 and the molecular weight distribution index of 1.3-1.5 of the prepolymer t