Temperature-resistant PVC protective film and preparation method thereof

Abstract

The invention relates to a temperature-resistant PVC protective film and a preparation method thereof, and belongs to the technical field of PVC protective films. Aiming at the problem of failure of a bonding layer caused by migration of a plasticizer of the existing PVC protective film in a medium-high temperature environment, the invention provides a dynamic barrier concept of resisting migration by migration. The preparation method comprises the following steps: preparing the acrylate emulsion; carrying out graft polymerization on butyl acrylate, methyl methacrylate and polyethylene glycol monomethyl ether methacrylate to prepare a migration blocking agent; preparing a PVC base film; mixing an acrylate emulsion, a migration blocking agent and the like to prepare a pressure-sensitive adhesive; and coating and curing on the PVC base film. When the temperature rises, the migration blocking agent directionally migrates to a PVC / pressure-sensitive adhesive interface, a PEG chain segment and a plasticizer form a hydrogen bond to bind movement of the migration blocking agent and block a migration channel at the same time, and an acrylate chain segment enhances the interface bonding force. The protective film still keeps excellent bonding performance and stability in a medium-high temperature environment, and is suitable for high-temperature process protection in the precision manufacturing field of semiconductors, optical glass, LED devices and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of PVC protective film and relates to a temperature-resistant PVC protective film and a preparation method thereof. BACKGROUND

[0002] As a kind of low-cost, easy-to-process and balanced mechanical property surface protection material, polyvinyl chloride (PVC) protective film is widely used in semiconductor wafer cutting, optical glass processing, LED device processing, metal plate stamping and other precision manufacturing and industrial processing fields. Its typical composition is PVC film prepared by taking PVC resin as a base material, supplemented by functional additives such as plasticizer, heat stabilizer and lubricant as a bearing layer, and forming a complete protective structure by coating pressure-sensitive adhesive such as acrylic. Such protective film can effectively isolate the damage of dust, oil stains and scratches in the processing process to the surface of the pasted object, and has the characteristics of convenient pasting and smooth peeling. It is a key auxiliary material to protect the processing yield of precision components and occupies an important position in the electronic information, optical manufacturing and automobile parts industries.

[0003] However, in actual application, especially in the storage environment with rising temperature (such as above 35℃) or short-term mild high-temperature processing scene, the existing PVC protective film generally faces the problem of adhesive layer failure caused by plasticizer migration, which seriously limits its application in medium and high temperature demand scenarios. Specifically, as the core additive for realizing the flexibility and processability of PVC film, the plasticizer is mainly combined with PVC resin by intermolecular force, without stable chemical bond connection. When the environmental temperature rises, the PVC molecular chain segment movement intensifies, the intermolecular gap expands, and the kinetic energy of the plasticizer molecules significantly increases, which can easily overcome the force of action with PVC resin and migrate. The migrated plasticizer will gradually penetrate into the adhesive layer formed by the PVC film and the pressure-sensitive adhesive, causing damage to the pressure-sensitive adhesive structure. The plasticizer will dilute the effective bonding components in the pressure-sensitive adhesive, reduce the crosslinking density of the pressure-sensitive adhesive, destroy its original network structure, and cause the interfacial bonding force of the pressure-sensitive adhesive to PVC substrate and the pasted object to be greatly attenuated. SUMMARY

[0004] The purpose of the present application is to provide a temperature-resistant PVC protective film and a preparation method thereof, which is beneficial to solve the problem of adhesive layer failure caused by plasticizer migration in the existing PVC protective film in medium and high temperature environment.

[0005] The purpose of the present application can be achieved by the following technical solutions:

[0006] In a first aspect, the present application provides a preparation method of a temperature-resistant PVC protective film, comprising the following steps:

[0007] A1. Mix butyl acrylate, methyl methacrylate, and hydroxyethyl acrylate, add emulsifier, ammonium persulfate initiator, buffer and deionized water, and polymerize. After pH adjustment and filtration, acrylate emulsion is obtained.

[0008] A2. Butyl acrylate and methyl methacrylate are mixed as acrylate monomers, and together with polyethylene glycol monomethyl ether methacrylate, azobisisobutyronitrile initiator and chain transfer agent, they are dissolved in a solvent and grafted under nitrogen protection. The solvent is removed by vacuum distillation and vacuum drying to obtain a migration barrier agent.

[0009] A3. PVC resin, plasticizer, heat stabilizer, lubricant and auxiliary antioxidant are pretreated and then mixed at high speed, followed by twin-screw extrusion plasticization, casting into a film, stretching and shaping and winding to obtain PVC base film;

[0010] A4. Mix and disperse the acrylic emulsion obtained in step A1 with the migration barrier agent obtained in step A2, then add a leveling agent, then add deionized water to adjust the viscosity, and finally add a crosslinking agent to mix and degas under vacuum to obtain a pressure-sensitive adhesive.

[0011] A5. After corona treatment, the PVC base film obtained in step A3 is coated with the pressure-sensitive adhesive obtained in step A4. After segmented drying and curing, pressing and cooling, winding and settling, a heat-resistant PVC protective film is obtained.

[0012] Preferably, the PEG segment of the polyethylene glycol monomethyl ether methacrylate is PEG-500.

[0013] Preferably, in step A1, the raw materials of the acrylate emulsion are, by weight, 45-55 parts butyl acrylate, 25-35 parts methyl methacrylate, 3-5 parts hydroxyethyl acrylate, 1.3-2.0 parts emulsifier, 0.3-0.5 parts ammonium persulfate initiator, 0.1-0.2 parts buffer, and 15-20 parts deionized water; the polymerization reaction temperature is 75±1℃, and the reaction time is 4-5 hours.

[0014] Preferably, in step A1, the emulsifier is a composite of sodium dodecylbenzenesulfonate and fatty alcohol polyoxyethylene ether.

[0015] Preferably, in step A2, the raw materials for the migration barrier agent, by weight, are: 75-85 parts acrylate monomer, 18-22 parts polyethylene glycol monomethyl ether methacrylate, 0.8-1.2 parts azobisisobutyronitrile initiator, 0.4-0.6 parts chain transfer agent, and 140-160 parts solvent; the graft polymerization temperature is 75±1℃, and the reaction time is 7-8 hours;

[0016] Preferably, in step A2, the weight ratio of butyl acrylate to methyl methacrylate is 3:1.

[0017] Preferably, in step A2, the chain transfer agent is dodecyl mercaptan and the solvent is ethyl acetate.

[0018] Preferably, in step A4, the weight ratio of the acrylate emulsion to the migration barrier is (8-10):1.

[0019] Preferably, in step A5, the corona treatment intensity is 38-42 dyn / cm; the dry adhesive thickness of the pressure-sensitive adhesive coating is 15-25 μm; the segmented drying and curing process is: pre-drying at 60℃ for 2 min, medium-temperature drying at 85℃ for 3 min, and curing at 100℃ for 2 min; the pressing pressure is 0.5-0.7 MPa, and the static conditions after winding are 25℃ and 50±5% humidity for 24 h.

[0020] Secondly, the present invention provides a heat-resistant PVC protective film, which is prepared according to the above-described preparation method.

[0021] The beneficial effects of this invention are:

[0022] The core innovation of this invention lies in proposing a dynamic barrier concept of "using migration to counteract migration." By designing and preparing a specific migration barrier agent (obtained by graft polymerization of polyethylene glycol monomethyl ether methacrylate and acrylate monomers), it effectively solves the problem of adhesive layer failure caused by plasticizer migration in existing PVC protective films under medium- and high-temperature conditions. The acrylate segments of the migration barrier agent have similar chemical structures to the main components of the pressure-sensitive adhesive, ensuring stable dispersion in the pressure-sensitive adhesive at room temperature without delamination or precipitation, thus guaranteeing the initial adhesion performance of the protective film. Furthermore, the PEG-500 segments, due to their molecular structure matching, exhibit significantly better compatibility with the PVC base film than the pressure-sensitive adhesive phase. When the ambient temperature rises, the movement of PVC molecular segments intensifies, and the intermolecular gaps widen. This not only provides a channel for plasticizer migration but also allows the migration barrier agent to rapidly migrate towards the interface between the PVC base film and the pressure-sensitive adhesive under the thermodynamic driving force of "PVC phase compatibility being greater than pressure-sensitive adhesive phase compatibility," achieving dynamic adaptation where "plasticizer migration triggers barrier agent migration response." After migration, the barrier agent rapidly self-assembles at the interface to form a barrier layer. On one hand, the hydroxyl groups of the PEG-500 segments form stable hydrogen bonds with the ester groups of the plasticizer molecules, directly binding the movement of the plasticizer molecules and weakening their migration kinetic energy. On the other hand, the barrier layer blocks the physical channels through which the plasticizer diffuses from the PVC base film to the pressure-sensitive adhesive layer, ultimately achieving a precise barrier effect of "dynamic migration against dynamic migration." Simultaneously, the interface layer formed by the migrated barrier agent also acts as an "anchor"—its acrylate segments are firmly anchored in the pressure-sensitive adhesive phase, while the PEG-500 segments are deeply embedded in the molecular gaps of the PVC base film, significantly strengthening the interfacial bonding between the PVC base film and the pressure-sensitive adhesive, effectively preventing delamination and separation problems caused by weak interfacial bonding under high-temperature environments. Detailed Implementation

[0023] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0024] Example 1

[0025] A method for preparing a heat-resistant PVC protective film, the specific steps of which are as follows:

[0026] A1. Preparation of acrylate emulsion: Accurately weigh 50 parts by weight of butyl acrylate, 30 parts by weight of methyl methacrylate, and 4 parts by weight of hydroxyethyl acrylate, and mix them evenly to obtain a monomer mixture. Add 18 parts by weight of deionized water to a four-necked flask, start stirring at 200 rpm, and add 1.6 parts by weight of emulsifier and 0.15 parts by weight of buffer sodium bicarbonate. The emulsifier consists of 1.08 parts by weight of sodium dodecylbenzenesulfonate and 0.52 parts by weight of fatty alcohol polyoxyethylene ether. Stir until completely dissolved. Place the four-necked flask in a constant temperature water bath and heat to 75°C. Add 0.4 parts by weight of ammonium persulfate initiator, stir for 5 minutes, and then slowly add the above monomer mixture dropwise, keeping the temperature stable at 75°C during the dropwise addition process. After the dropwise addition is complete, continue the polymerization at a constant temperature for 4.5 hours. After the reaction is complete, allow it to cool naturally to 40°C, adjust the pH of the emulsion to 7.0 with 25% ammonia water, and filter through a 200-mesh filter to obtain the acrylate emulsion.

[0027] A2. Preparation of migration blocking agent: Weigh 60 parts by weight of butyl acrylate and 20 parts by weight of methyl methacrylate in a weight ratio of 3:1, and mix them evenly to obtain 80 parts of acrylate monomer. Add the acrylate monomer, 20 parts of polyethylene glycol monomethyl ether methacrylate, 1 part of azobisisobutyronitrile initiator, 0.5 parts of chain transfer agent dodecyl mercaptan, and 150 parts of solvent ethyl acetate to a three-necked flask. Start stirring at 250 r / min and purge with nitrogen three times, 5 min each time. Place the three-necked flask in an oil bath and heat to 75°C. Graft polymerization is carried out at a constant temperature under nitrogen protection for 7.5 hours. After the reaction is completed, cool down to 40°C, stop nitrogen purging, and transfer the reaction solution to a rotary evaporator. Remove ethyl acetate by vacuum distillation at 60°C and -0.09 MPa. The residue is dried under vacuum at 80°C for 8 hours to obtain the migration blocking agent, wherein the PEG segment of polyethylene glycol monomethyl ether methacrylate is PEG-500.

[0028] A3. Preparation of PVC base film: Take 100 parts by weight of PVC resin (SG-5 type) and dry it in an 80℃ forced-air drying oven for 2 hours; separately weigh 40 parts of plasticizer dioctyl phthalate, 2.0 parts of heat stabilizer methyl mercaptan, 1.0 part of lubricant butyl stearate, and 0.4 parts of auxiliary antioxidant triphenyl phosphite, and mix them to prepare a premixed additive package. The dried PVC resin and premixed additive package were added to a high-speed mixer and mixed at 800 r / min and 80℃ for 15 min before being discharged. The material was then fed into a twin-screw extruder, with the following temperatures set: feeding section 120℃, compression section 140℃, plasticizing section 160℃, and die head section 160℃. The screw speed was 300 r / min. The molten material was cast through a T-die to a 25℃ cooling roller and stretched longitudinally at a traction speed of 6 m / min with a stretch ratio of 1.2:1. After a second cooling and shaping at 20℃, the material was wound up under 70N tension to obtain a 75μm thick PVC base film.

[0029] A4. Preparation of pressure-sensitive adhesive: By weight, take 90 parts of the acrylic emulsion obtained in step A1 and add it to the mixing tank, stir at 350 r / min for 5 min; slowly add 10 parts of the migration barrier agent obtained in step A2, with a weight ratio of 9:1, and keep stirring at 350 r / min for 50 min; add 0.25 parts of leveling agent polyether modified organosiloxane (BYK-333), and stir for 20 min; add 12 parts of deionized water to adjust the viscosity to 2000 mPa·s, and test at 25℃; finally, add 2.5 parts of aliphatic polyurethane crosslinking agent (Covestro N3390), stir at 200 r / min for 25 min, transfer to a vacuum degassing machine, and degas at -0.08 MPa for 35 min to obtain the pressure-sensitive adhesive.

[0030] A5. Preparation of heat-resistant PVC protective film: The PVC base film obtained in step A3 is subjected to corona treatment with a treatment strength of 40 dyn / cm; the pressure-sensitive adhesive obtained in step A4 is coated onto the corona-treated surface of the base film using a comma-shaped doctor blade coater, controlling the dry adhesive thickness to 20 μm and the coating speed to 5 m / min; after coating, the base film is sent to a multi-layer oven for segmented drying and curing, in sequence: pre-drying at 60℃ for 2 min, medium-temperature drying at 85℃ for 3 min, and curing at 100℃ for 2 min, with an oven wind speed of 2.5 m / s; then, it is pressed under a pressure of 0.6 MPa and a temperature of 40℃, cooled by a 25℃ cooling roller, and wound up under a tension of 80 N; after winding, the film is placed in an environment of 25℃ and 50% relative humidity for 24 hours to obtain the finished heat-resistant PVC protective film.

[0031] Example 2

[0032] A method for preparing a heat-resistant PVC protective film, the specific steps of which are as follows:

[0033] A1. Preparation of acrylate emulsion: Accurately weigh 45 parts by weight of butyl acrylate, 25 parts by weight of methyl methacrylate, and 3 parts by weight of hydroxyethyl acrylate, and mix them evenly to obtain a monomer mixture. Add 15 parts by weight of deionized water to a four-necked flask, start stirring at 200 rpm, and add 1.3 parts by weight of emulsifier and 0.1 parts by weight of buffer sodium bicarbonate. The emulsifier consists of 0.78 parts by weight of sodium dodecylbenzenesulfonate and 0.52 parts by weight of fatty alcohol polyoxyethylene ether. Stir until completely dissolved. Place the four-necked flask in a constant temperature water bath and heat to 74°C. Add 0.3 parts by weight of ammonium persulfate initiator, stir for 5 minutes, and then slowly add the above monomer mixture dropwise, keeping the temperature stable at 74°C during the dropwise addition process. After the dropwise addition is complete, continue polymerization at a constant temperature for 4 hours. After the reaction is complete, allow it to cool naturally to 40°C, adjust the pH of the emulsion to 7.0 with 25% ammonia water, and filter through a 200-mesh filter to obtain the acrylate emulsion.

[0034] A2. Preparation of migration blocking agent: Weigh 56.25 parts by weight of butyl acrylate and 18.75 parts by weight of methyl methacrylate in a weight ratio of 3:1, and mix them evenly to obtain 75 parts of acrylate monomer. Add the acrylate monomer, 18 parts of polyethylene glycol monomethyl ether methacrylate, 0.8 parts of azobisisobutyronitrile initiator, 0.4 parts of chain transfer agent dodecyl mercaptan, and 140 parts of solvent ethyl acetate to a three-necked flask. Start stirring at 250 r / min and purge with nitrogen three times for 5 min each time. Place the three-necked flask in an oil bath and heat to 74°C. Graft polymerization is carried out at a constant temperature under nitrogen protection for 8 hours. After the reaction is completed, cool down to 40°C, stop nitrogen purging, and transfer the reaction solution to a rotary evaporator. Remove ethyl acetate by vacuum distillation at 60°C and -0.09 MPa. The residue is dried under vacuum at 80°C for 8 hours to obtain the migration blocking agent, wherein the PEG segment of polyethylene glycol monomethyl ether methacrylate is PEG-500.

[0035] A3. Preparation of PVC base film: Take 100 parts by weight of PVC resin (SG-5 type) and dry it in an 80℃ forced-air drying oven for 2 hours; separately weigh 40 parts of plasticizer dioctyl phthalate, 2.0 parts of heat stabilizer methyl mercaptan, 1.0 part of lubricant butyl stearate, and 0.4 parts of auxiliary antioxidant triphenyl phosphite, and mix them to prepare a premixed additive package. The dried PVC resin and premixed additive package were added to a high-speed mixer and mixed at 800 r / min and 80℃ for 15 min before being discharged. The material was then fed into a twin-screw extruder, with the following temperatures set: feeding section 120℃, compression section 140℃, plasticizing section 160℃, and die head section 160℃. The screw speed was 300 r / min. The molten material was cast through a T-die to a 25℃ cooling roller and stretched longitudinally at a traction speed of 6 m / min with a stretch ratio of 1.2:1. After a second cooling and shaping at 20℃, the material was wound up under 70N tension to obtain a 75μm thick PVC base film.

[0036] A4. Preparation of pressure-sensitive adhesive: By weight, take 80 parts of the acrylic emulsion obtained in step A1 and add it to the mixing tank, stir at 350 r / min for 5 min; slowly add 10 parts of the migration barrier agent obtained in step A2, with a weight ratio of 8:1, and keep stirring at 350 r / min for 50 min; add 0.2 parts of leveling agent polyether modified organosiloxane (BYK-333), and stir for 20 min; add 10 parts of deionized water to adjust the viscosity to 1500 mPa·s, and test at 25℃; finally, add 2.0 parts of aliphatic polyurethane crosslinking agent (Covestro N3390), stir at 200 r / min for 25 min, transfer to a vacuum degassing machine, and degas at -0.08 MPa for 35 min to obtain the pressure-sensitive adhesive.

[0037] A5. Preparation of heat-resistant PVC protective film: The PVC base film obtained in step A3 is subjected to corona treatment with a treatment strength of 38 dyn / cm; the pressure-sensitive adhesive obtained in step A4 is coated onto the corona-treated surface of the base film using a comma-shaped doctor blade coater, controlling the dry adhesive thickness to 15 μm and the coating speed to 5 m / min; after coating, the base film is sent to a multi-layer oven for segmented drying and curing, in sequence: pre-drying at 60℃ for 2 min, medium-temperature drying at 85℃ for 3 min, and curing at 100℃ for 2 min, with an oven wind speed of 2.5 m / s; then, it is pressed under 0.5 MPa pressure and 40℃, cooled by a 25℃ cooling roller, and wound up under 80N tension; after winding, the film is placed in an environment of 25℃ and 50% relative humidity for 24 hours to obtain the finished heat-resistant PVC protective film.

[0038] Example 3

[0039] A method for preparing a heat-resistant PVC protective film, the specific steps of which are as follows:

[0040] A1. Preparation of acrylate emulsion: Accurately weigh 55 parts by weight of butyl acrylate, 35 parts by weight of methyl methacrylate, and 5 parts by weight of hydroxyethyl acrylate, and mix them evenly to obtain a monomer mixture. Add 20 parts by weight of deionized water to a four-necked flask, start stirring at 200 rpm, and add 2.0 parts by weight of composite emulsifier and 0.2 parts by weight of buffer sodium bicarbonate, wherein the emulsifier consists of 1.33 parts by weight of sodium dodecylbenzenesulfonate and 0.67 parts by weight of fatty alcohol polyoxyethylene ether, and stir until completely dissolved. Place the four-necked flask in a constant temperature water bath and heat to 76°C. Add 0.5 parts by weight of ammonium persulfate initiator, stir for 5 minutes, and then slowly add the above monomer mixture dropwise, keeping the temperature stable at 76°C during the dropwise addition process. After the dropwise addition is completed, continue the constant temperature polymerization for 5 hours. After the reaction is completed, allow it to cool naturally to 40°C, adjust the pH of the emulsion to 7.0 with 25% ammonia water, and filter through a 200-mesh filter to obtain the acrylate emulsion.

[0041] A2. Preparation of migration blocking agent: 63.75 parts by weight of butyl acrylate and 21.25 parts by weight of methyl methacrylate (3:1 weight ratio) were weighed and mixed thoroughly to obtain 85 parts of acrylate monomer. This acrylate monomer, 22 parts of polyethylene glycol monomethyl ether methacrylate, 1.2 parts of azobisisobutyronitrile initiator, 0.6 parts of chain transfer agent dodecyl mercaptan, and 160 parts of solvent ethyl acetate were added to a three-necked flask. Stirring was started at 250 rpm, and nitrogen was purged three times for 5 minutes each time. The three-necked flask was placed in an oil bath and heated to 76°C. Graft polymerization was carried out at this temperature for 7 hours under nitrogen protection. After the reaction, the temperature was lowered to 40°C, nitrogen purging was stopped, and the reaction solution was transferred to a rotary evaporator. Ethyl acetate was removed by vacuum distillation at 60°C and -0.09 MPa. The residue was dried under vacuum at 80°C for 8 hours to obtain the migration blocking agent, wherein the PEG segment of the polyethylene glycol monomethyl ether methacrylate was PEG-500.

[0042] A3. Preparation of PVC base film: Take 100 parts by weight of PVC resin (SG-5 type) and dry it in an 80℃ forced-air drying oven for 2 hours; separately weigh 40 parts of plasticizer dioctyl phthalate, 2.0 parts of heat stabilizer methyl mercaptan, 1.0 part of lubricant butyl stearate, and 0.4 parts of auxiliary antioxidant triphenyl phosphite, and mix them to prepare a premixed additive package. The dried PVC resin and premixed additive package were added to a high-speed mixer and mixed at 800 r / min and 80℃ for 15 min before being discharged. The material was then fed into a twin-screw extruder, with the following temperatures set: feeding section 120℃, compression section 140℃, plasticizing section 160℃, and die head section 160℃. The screw speed was 300 r / min. The molten material was cast through a T-die to a 25℃ cooling roller and stretched longitudinally at a traction speed of 6 m / min with a stretch ratio of 1.2:1. After a second cooling and shaping at 20℃, the material was wound up under 70N tension to obtain a 75μm thick PVC base film.

[0043] A4. Preparation of pressure-sensitive adhesive: By weight, take 100 parts of the acrylic emulsion obtained in step A1 and add it to the mixing tank, stir at 350 r / min for 5 min; slowly add 10 parts of the migration barrier agent obtained in step A2, with a weight ratio of 10:1, and keep stirring at 350 r / min for 50 min; add 0.3 parts of the leveling agent polyether modified organosiloxane (BYK-333), and stir for 20 min; add 15 parts of deionized water to adjust the viscosity to 2500 mPa·s, and test at 25℃; finally, add 3.0 parts of aliphatic polyurethane crosslinking agent (Covestro N3390), stir at 200 r / min for 25 min, transfer to a vacuum degassing machine, and degas at -0.08 MPa for 35 min to obtain the pressure-sensitive adhesive.

[0044] A5. Preparation of heat-resistant PVC protective film: The PVC base film obtained in step A3 is subjected to corona treatment with a treatment strength of 42 dyn / cm; the pressure-sensitive adhesive obtained in step A4 is coated onto the corona-treated surface of the base film using a comma-shaped doctor blade coater, controlling the dry adhesive thickness to 25 μm and the coating speed to 5 m / min; after coating, the base film is sent to a multi-layer oven for segmented drying and curing, in sequence: pre-drying at 60℃ for 2 min, medium-temperature drying at 85℃ for 3 min, and curing at 100℃ for 2 min, with an oven wind speed of 2.5 m / s; then, it is pressed under a pressure of 0.7 MPa and a temperature of 40℃, cooled by a 25℃ cooling roller, and wound up under a tension of 80 N; after winding, the film is placed in an environment of 25℃ and 50% relative humidity for 24 hours to obtain the finished heat-resistant PVC protective film.

[0045] Comparative Example 1

[0046] The difference from Example 1 is that in step A4, when preparing the pressure-sensitive adhesive, no migration barrier agent is added. Instead, 90 parts of acrylic emulsion are directly mixed with 0.25 parts of leveling agent, 12 parts of deionized water and 2.5 parts of crosslinking agent to obtain the pressure-sensitive adhesive. The remaining steps are exactly the same as in Example 1.

[0047] Comparative Example 2

[0048] The difference from Example 1 is that in step A2, polyethylene glycol monomethyl ether methacrylate is not used. Instead, 80 parts of acrylate monomers (60 parts of butyl acrylate and 20 parts of methyl methacrylate), 1 part of azobisisobutyronitrile initiator, and 0.5 parts of dodecanethiol chain transfer agent are dissolved in 150 parts of ethyl acetate for polymerization to obtain a common acrylic resin without PEG segments as a comparative migration barrier. In step A4, this comparative migration barrier is used instead of the migration barrier, and the remaining steps are exactly the same as in Example 1.

[0049] Comparative Example 3

[0050] The difference from Example 1 is that in step A2, polyethylene glycol monomethyl ether methacrylate is replaced with polyethylene glycol (PEG-500) small molecules, and graft polymerization is not performed. Instead, 20 parts of PEG-500 small molecules are directly used as additives. In step A4, 10 parts of PEG-500 small molecules are directly dispersed in 90 parts of acrylate emulsion to obtain pressure-sensitive adhesive. The remaining steps are exactly the same as in Example 1.

[0051] Comparative Example 4

[0052] The difference from Example 1 is that in step A2, when preparing the migration barrier, the PEG segment of polyethylene glycol monomethyl ether methacrylate is replaced with PEG-200 instead of PEG-500 (other structures are the same), and the remaining raw material ratios and process parameters are completely the same as in Example 1.

[0053] Comparative Example 5

[0054] The difference from Example 1 is that in step A2, when preparing the migration barrier, the PEG segment of polyethylene glycol monomethyl ether methacrylate is replaced with PEG-1000 instead of PEG-500 (other structures are the same), and the remaining raw material ratios and process parameters are completely the same as in Example 1.

[0055] Test Example 1

[0056] Test subjects: heat-resistant PVC protective films prepared in Examples 1-3 and Comparative Examples 1-5.

[0057] Test method: Cut each test sample into a 50mm×50mm square specimen and accurately weigh the initial mass (m0) for later use; select ethyl acetate as the extraction medium, and immerse the specimen completely in the extraction solution at a liquid-to-solid ratio of 50mL:1g, place it in a constant temperature water bath at 45℃ for 72h; after the incubation period, remove the specimen, quickly clean the surface of the residual extraction solution with anhydrous ethanol, place it in an 80℃ vacuum drying oven to constant weight and accurately weigh the mass after drying (m1), and calculate the plasticizer migration rate of each specimen according to the formula migration rate = (m0-m1) / m0×100%.

[0058] The data for Test Example 1 is shown in Table 1.

[0059] Table 1

[0060] As shown in Table 1, the plasticizer migration rate of Examples 1-3 was significantly lower than that of all comparative examples, only 1.2%-1.8%, while the migration rate of Comparative Example 1 without the addition of migration barrier was as high as 8.5%. This indicates that the migration barrier designed in this invention (especially the structure containing PEG-500 segments) can effectively inhibit the migration of plasticizer from the PVC base film to the pressure-sensitive adhesive layer. When PEG-200 and PEG-1000 were used to replace PEG-500 in Comparative Examples 4-5, the migration rate was improved but still did not reach the level of the examples. This confirms that the PEG-500 segments have a better blocking effect in this system and can accurately match the size of the plasticizer molecules and form effective hydrogen bond binding.

[0061] Test Example 2

[0062] Test subjects: heat-resistant PVC protective films prepared in Examples 1-3 and Comparative Examples 1-5.

[0063] Test method: Each test sample was cut into 25mm×200mm specimens. Optical glass was selected as the substrate. The bonding was completed according to GB / T2792-2014 standard with a bonding pressure of 0.5MPa and a bonding speed of 300mm / min. After bonding, the samples were left to stand at room temperature for 2 hours. The bonded samples were then placed in a 45℃ constant temperature chamber for 96 hours. After being removed, they were allowed to recover at room temperature (25℃) for 2 hours. Subsequently, the 180° peel strength was tested using an electronic universal testing machine at a speed of 300mm / min, and the state of adhesive layer delamination, separation, and residual adhesive was recorded. At the same time, according to GB / T4851-2014 standard, the 25mm×100mm bonded samples were fixed on a 45℃ constant temperature rack with a 1kg weight applied, and the adhesive layer failure time was recorded.

[0064] The data for Test Example 2 are shown in Table 2.

[0065] Table 2

[0066] As shown in Table 2, after being stored at a high temperature of 45℃ for 96 hours, Examples 1-3 still maintained excellent adhesive performance, with a stable 180° peel strength of 1.8-2.2 N / 25 mm and an adhesive failure time exceeding 120 hours, without any delamination or residue. In contrast, Comparative Example 1 (without migration barrier agent) had a peel strength of only 0.5 N / 25 mm, and severe delamination occurred after 24 hours. Comparative Examples 2-3 (without PEG structure or with direct addition of small PEG molecules) showed some improvement but were still not ideal. Comparative Examples 4-5 (PEG with different molecular weights) had performance between the two, demonstrating that the specific structure of the migration barrier agent in this invention can not only effectively block the migration of plasticizers, but its acrylate segments can also form an "anchor" effect at the interface, significantly enhancing the interfacial bonding force between the PVC base film and the pressure-sensitive adhesive.

[0067] Test Example 3: Simulated Protective Performance Test in High-Temperature Processing Scenarios

[0068] Test subjects: heat-resistant PVC protective films prepared in Examples 1-3 and Comparative Examples 1-5.

[0069] Test method: A stainless steel substrate used for semiconductor wafer dicing was selected as the substrate. Each test sample was cut into 50mm×50mm pieces. The bonding was completed according to the actual processing technology with a bonding pressure of 0.6MPa and a bonding temperature of 30℃ and then left to stand for 1 hour. The bonded samples were placed in a 60℃ hot air circulating oven and heated for 30 minutes to simulate a short-term high-temperature processing process. After being removed, the samples were allowed to cool naturally to room temperature. The protective film was then peeled off according to the actual peeling process at a speed of 500mm / min in a 180° direction. The residual adhesive, scratches, and plasticizer migration residue on the surface of the stainless steel substrate were observed.

[0070] The data for Test Example 3 are shown in Table 3.

[0071] As shown in Table 3, in simulated high-temperature processing scenarios such as semiconductor wafer dicing at 60°C, Examples 1-3 performed exceptionally well. After peeling, the substrate surface was free of adhesive residue, scratches, and plasticizer migration residue, maintaining a high level of cleanliness. In contrast, Comparative Examples 1-3 exhibited varying degrees of adhesive residue and oily residue, affecting the substrate surface quality. Although Comparative Examples 4-5 showed some improvement, trace amounts of adhesive residue or hazy residue still remained. This confirms that the protective film of the present invention can effectively maintain the integrity of the adhesive layer in short-term high-temperature processes. Its dynamic barrier mechanism of "using migration to counteract migration" has significant advantages in actual high-temperature application scenarios and can perfectly meet the stringent requirements for surface protection in the precision manufacturing field.

[0072] In summary, this invention, through the innovative design of a migration barrier agent with PEG-500 segments, successfully achieves a dynamic barrier mechanism of "using migration to counteract migration," significantly inhibiting plasticizer migration under medium and high temperature environments. This greatly enhances the interfacial adhesion and long-term stability of the PVC protective film, with all performance indicators significantly superior to traditional PVC protective films and various comparative solutions. It is particularly suitable for high-temperature process protection in precision manufacturing fields such as semiconductors, optical glass, and LED devices, and has significant application value and industrialization prospects.

[0073] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing a temperature-resistant PVC protective film, characterized in that, It comprises the following steps: A1, butyl acrylate, methyl methacrylate, hydroxyethyl acrylate are mixed, emulsifier, ammonium persulfate initiator, buffer and deionized water are added, polymerization reaction, then pH adjustment, filtration, prepared acrylate emulsion; A2, butyl acrylate, methyl methacrylate is mixed as acrylate monomer, with polyethylene glycol monomethyl ether methacrylate, azobis isobutyronitrile initiator, chain transfer agent is dissolved in solvent, graft polymerization under nitrogen protection condition, solvent is removed by vacuum distillation, vacuum drying, get migration barrier; A3, PVC resin, plasticizer, heat stabilizer, lubricant, auxiliary antioxidant are pretreated, then high speed mixing, again through double screw extrusion plasticization, casting film, stretching and shaping and winding, prepared PVC base film; A4, the acrylate emulsion prepared in step A1 is mixed and dispersed with the migration barrier prepared in step A2, then a leveling agent is added, deionized water is added to adjust the viscosity, and finally a crosslinking agent is added and vacuum degassing to prepare a pressure sensitive adhesive; A5, the PVC base film prepared in step A3 is treated by corona treatment, then the pressure sensitive adhesive prepared in step A4 is coated, and then it is sequentially subjected to sectional drying and curing, pressing and cooling, winding and post treatment to obtain a temperature resistant PVC protective film.

2. The preparation method of the temperature-resistant PVC protective film according to claim 1, characterized in that, The PEG segment of the polyethylene glycol monomethyl ether methacrylate is PEG-500.

3. The preparation method of the temperature-resistant PVC protective film according to claim 1, characterized in that, In step A1, the raw materials of the acrylate emulsion are butyl acrylate 45-55 parts, methyl methacrylate 25-35 parts, hydroxyethyl acrylate 3-5 parts, emulsifier 1.3-2.0 parts, ammonium persulfate initiator 0.3-0.5 parts, buffer 0.1-0.2 parts, and deionized water 15-20 parts; the polymerization reaction temperature is 75±1℃, and the reaction time is 4-5 hours.

4. The preparation method of the temperature-resistant PVC protective film according to claim 1, characterized in that, In step A1, the emulsifier is a composite of sodium dodecyl benzene sulfonate and fatty alcohol polyoxyethylene ether.

5. The preparation method of the temperature-resistant PVC protective film according to claim 1, characterized in that, In step A2, the raw materials of the migration barrier are acrylate monomer 75-85 parts, polyethylene glycol monomethyl ether methacrylate 18-22 parts, azobis isobutyronitrile initiator 0.8-1.2 parts, chain transfer agent 0.4-0.6 parts, and solvent 140-160 parts; the graft polymerization temperature is 75±1℃, and the reaction time is 7-8 hours.

6. The preparation method of the temperature-resistant PVC protective film according to claim 1, characterized in that, In step A2, the weight ratio of butyl acrylate to methyl methacrylate is 3:

1.

7. The preparation method of the temperature-resistant PVC protective film according to claim 1, characterized in that, In step A2, the chain transfer agent is dodecanethiol, and the solvent is ethyl acetate.

8. The preparation method of the temperature-resistant PVC protective film according to claim 1, characterized in that, In step A4, the weight ratio of the acrylate emulsion to the migration barrier is (8-10):

1.

9. The preparation method of the temperature-resistant PVC protective film according to claim 1, characterized in that, In step A5, the corona treatment intensity is 38-42 dyn / cm; the dry adhesive thickness of the coated pressure sensitive adhesive is 15-25μm; the sectional drying and curing process is: 60℃ pre-drying for 2min, 85℃ medium temperature drying for 3min, and 100℃ curing for 2min; the pressing pressure is 0.5-0.7MPa, and the standing condition after winding is 25℃, 50±5% humidity for 24h.

10. A temperature resistant PVC protective film, characterized in that: Prepared according to the preparation method of any one of claims 1-9. Prepared according to the preparation method of any one of claims 1-9.

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