High-temperature-resistant composite protective film and preparation method thereof
By introducing organosilicon-modified diamine and polyether polyol into polyurethane prepolymer and reacting them with diisocyanate, combined with antistatic agents and chlorinated paraffin, a high-temperature resistant composite protective film was prepared. This solved the problems of poor temperature resistance and unstable peel force of polyurethane pressure-sensitive adhesive layer at high temperatures, and achieved the effects of high light transmittance, low haze and no adhesive residue.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- FOSHAN WEILIXIN ELECTRONICS MATERIAL
- Filing Date
- 2026-04-08
- Publication Date
- 2026-05-29
AI Technical Summary
Existing polyurethane pressure-sensitive adhesive layers have poor temperature resistance at high temperatures, unstable peel strength, and are prone to leaving residue, which affects the performance of electronic protective films.
The process involves introducing organosilicon-modified diamine and polyether polyol into a polyurethane prepolymer and reacting them with diisocyanate to increase the crosslinking density. Antistatic agents and chlorinated paraffin are also added, and the mixture is cured at high temperature to form a high-temperature resistant composite protective film.
It improves the high temperature resistance and peel strength stability of the protective film, reduces haze and adhesive residue, and enhances optical and adhesion properties.
Smart Images
Figure CN122104083A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of electronic protective films, and in particular to a high-temperature resistant composite protective film and its preparation method. Background Technology
[0002] Protective films are a general term for functional films that protect product surfaces from damage or contamination, and are widely used in electronics, automotive, and food preservation industries. Electronic protective films are mainly used to protect the screens of electronic devices. Their application can solve problems such as contamination, impacts, and scratches that affect the quality of electronic devices, improve production yield, reduce costs, and extend product lifespan.
[0003] Electronic protective films can be summarized into a three-layer structure: the middle layer is the substrate, commonly made of polyethylene terephthalate (PET) film; one side of the middle layer is coated with adhesive material, i.e., the adhesive layer, and a release film is attached to the other side of the adhesive layer to isolate dust and other contaminants; the other side of the middle layer is the surface layer, mainly containing functional coatings such as anti-blue light coatings and anti-static coatings. The adhesive material is usually a pressure-sensitive adhesive, commonly made of acrylic, polyurethane, or silicone. During use, the adhesive material connects the protective film substrate and the protected object at both ends, directly determining the performance of the electronic protective film.
[0004] With the development of technology, especially the popularity of flexible screens and precision optical devices, the requirements for electronic protective films are becoming increasingly stringent. Polyurethane pressure-sensitive adhesives, with their advantages of good controllability, stable adhesion, no powder shedding during die-cutting, and no silicon transfer, are suitable for the electronic protective film field. However, most polyurethane pressure-sensitive adhesive layers generally suffer from poor temperature resistance, adhesive residue, and unstable peel strength, requiring further improvement. Summary of the Invention
[0005] In order to provide an electronic protective film with good temperature resistance, no adhesive residue, stable peel strength and excellent optical performance, this application provides a high-temperature resistant composite protective film and its preparation method.
[0006] The high-temperature resistant composite protective film and its preparation method provided in this application adopt the following technical solution: In a first aspect, this application discloses a high-temperature resistant composite protective film, comprising a substrate layer, an adhesive layer, and a release layer disposed sequentially. The adhesive layer is formed by coating with an adhesive material, which comprises the following raw materials in parts by weight: 58-73 parts of polyurethane prepolymer; 5-11 parts of isocyanate curing agent; 0.5-2 parts of antistatic agent; 1-3 parts of chlorinated paraffin; and 30-55 parts of diluent. The polyurethane prepolymer comprises the following raw materials in parts by weight: 80-86 parts of organosilicon-modified diamine; 60-75 parts of polyether diol; 34-38 parts of diisocyanate; 0.2-0.4 parts of catalyst; 4-7 parts of chain extender; and 60-80 parts of solvent. Organosilicon-modified diamines were prepared by anionic ring-opening polymerization of octamethylcyclotetrasiloxane and 1,3-bis(aminopropane)tetramethyldisiloxane.
[0007] By adopting the above technical solution, polyurethane pressure-sensitive adhesive is selected as the adhesive material in the adhesive layer of the composite protective film. In the polyurethane prepolymer, organosilicon-modified diamine and polyether polyol are selected as soft segments and reacted with diisocyanate. By introducing organosilicon, the rigidity and crosslinking density of polyurethane are improved, thereby enhancing the high temperature resistance of the protective film. At the same time, the polyurea formed by diisocyanate and amino can restrict the movement of polyurethane molecular chains, thereby improving the phenomenon of peel force increase and yellowing of traditional polyurethane pressure-sensitive adhesives at high temperatures. Moreover, the protective film has low haze and excellent optical properties. The cohesive strength of polyurethane is enhanced by chain extender, and the crosslinking strength of molecular chains is further improved by high temperature curing, avoiding the increase of peel force at high temperatures, so that the protective film leaves no residue.
[0008] Furthermore, an antistatic agent was added to the adhesive material to reduce the peeling voltage and prevent damage to electronic devices. Chlorinated paraffin, as a liquid filler and auxiliary plasticizer, reduced viscosity and minimized internal bubbles and defects after curing. Thus, through the combination of adhesive layer raw materials, the prepared composite protective film exhibits high light transmittance, low haze, good adhesion, stable peel strength, high temperature resistance, and no adhesive residue.
[0009] Optionally, the organosilicon-modified diamine is prepared by the following steps: Add 25-30 parts of monomer octamethylcyclotetrasiloxane and 2-5 parts of end-capping agent 1,3-bis(aminopropane)tetramethyldisiloxane to the reactor, start stirring and heat to 77-80℃, add 0.1-0.3 parts of tetramethylammonium hydroxide pentahydrate under nitrogen atmosphere, and heat to 85-88℃ to carry out ring-opening polymerization reaction; After the viscosity of the reaction system no longer changes, the system temperature is raised to 145-150℃ and kept at that temperature for 0.5-1h. Then, a vacuum is drawn to remove unreacted monomers and other oligomers from the system. The system is then cooled to room temperature to obtain organosilicon-modified diamine.
[0010] By adopting the above technical solution, octamethylcyclotetrasiloxane and 1,3-bis(aminopropane)tetramethyldisiloxane are selected to form organosilicon diamine. The molecular weight of the organosilicon-modified diamine is controlled by the ratio of raw materials, so that the molecular chain of organosilicon soft segment has a certain degree of flexibility, which can better wet and bond the substrate and electronic screen, and at the same time, migration will not occur due to excessive organosilicon content.
[0011] Optionally, the polyether diol is selected from one of polytetrahydrofuran ether diol, polyoxypropylene diol, or epoxy-modified polytetrahydrofuran ether diol.
[0012] Optionally, the epoxy-modified polytetrahydrofuran ether diol is prepared by the following steps: Polytetrahydrofuran ether diol was dehydrated under vacuum at 100-120℃ for 2-3 hours, then cooled to 60-80℃. 7%-12% of epichlorohydrin by mass of polytetrahydrofuran ether diol was added, followed by the addition of 0.5%-1% of boron trifluoride diethyl ether by mass of epichlorohydrin. The mixture was reacted at 70-90℃ for 4-6 hours. After neutralization and washing with water to remove the boron trifluoride diethyl ether, the product was dried under vacuum to obtain epoxy-modified polytetrahydrofuran ether diol.
[0013] By adopting the above technical solution, epoxy groups are introduced into the polyether molecular chain through the ring-opening reaction of polyether diol and epoxy monomer, and crosslinking points are formed by reacting with isocyanate, thereby increasing the crosslinking density and cohesive strength, further improving thermal stability, and also helping to improve the adhesion and bonding strength between the protective film and the substrate surface.
[0014] Optionally, the diisocyanate is selected from dicyclohexylmethane diisocyanate, and the catalyst is selected from dibutyltin dilaurate.
[0015] By adopting the above technical solution, alicyclic isocyanates are selected, and the rigidity of the molecular chain is improved through the cyclic structure.
[0016] Optionally, the chain extender may be one or more of isophorone diamine, trimethylolpropane, and propylene glycol.
[0017] By adopting the above technical solution, diisocyanate is further consumed by chain extender to prepare hydroxyl- or amino-terminated polyurethane prepolymers.
[0018] Optionally, the diluent and solvent are selected from one or more of ethyl acetate, butyl acetate, tetrahydrofuran, toluene, acetone, and butanone.
[0019] Optionally, the antistatic agent is selected from one or more of octadecyl dimethyl hydroxyethyl quaternary ammonium nitrate, tetramethyl ammonium oxalate, tributylmethyl ammonium bis(trifluoromethanesulfonyl)imide, and N-methyl-N-butylpyrrolidine bis(trifluoromethanesulfonyl)imide.
[0020] By adopting the above technical solution, the antistatic agent can be directly mixed with the pressure-sensitive adhesive, avoiding the problem of the antistatic agent precipitating out of the adhesive layer.
[0021] Optionally, the substrate layer is made of PET film with a thickness of 50-80μm; the release layer is made of PET release film with a thickness of 20-50μm.
[0022] Secondly, this application discloses a method for preparing a high-temperature resistant composite protective film, comprising the following steps: S1. Preparation of polyurethane prepolymer: The organosilicon-modified diamine is dried, and the polyether diol is dehydrated under vacuum. Then, the organosilicon-modified diamine and polyether diol are dissolved in part of the solvent to obtain a mixture. The other part of the solvent, diisocyanate and catalyst are added to the reaction flask, stirred and heated to 55-60℃, and the mixture is added dropwise. The temperature is raised to 75-80℃ and reacted for 2-3 hours. The chain extender is added and reacted for 1.5-2 hours to obtain the polyurethane prepolymer. S2. Preparation of adhesive material: Mix polyurethane prepolymer, isocyanate curing agent, antistatic agent, chlorinated paraffin and diluent evenly to obtain adhesive material; S3. Preparation of composite protective film: The prepared adhesive material is coated on the substrate layer and baked in an oven at 120-125℃ for 1-3 minutes. The thickness of the adhesive layer is controlled to be 4-8μm. After curing, a release film is attached to the side of the adhesive layer that is in contact with the substrate layer. The film is then placed in an oven at 60-65℃ for 24 hours to mature, and then removed to obtain the composite protective film.
[0023] By adopting the above technical solution, a composite protective film with good temperature resistance, high transparency, and excellent performance is obtained by combining the adhesive layer, the substrate, and the release film.
[0024] In summary, this application has at least one of the following beneficial effects: 1. In the adhesive layer of the composite protective film, polyurethane pressure-sensitive adhesive is selected as the adhesive material, which has the advantages of good controllability, stable adhesion, and no powdering during die-cutting. In the polyurethane prepolymer, organosilicon-modified diamine and polyether polyol are selected as soft segments and reacted with diisocyanate. By introducing organosilicon, the rigidity and crosslinking density of polyurethane are improved, thereby enhancing the high temperature resistance of the protective film. At the same time, the polyurea formed by diisocyanate and amino can restrict the movement of polyurethane molecular chains, thereby improving the phenomenon of peel force increase and yellowing of traditional polyurethane pressure-sensitive adhesives at high temperatures. The protective film has low haze and excellent optical properties. The cohesive strength of polyurethane is enhanced by chain extender, and high temperature curing is used to further improve the crosslinking strength of molecular chains, avoiding the increase of peel force at high temperatures, so that the protective film leaves no residue.
[0025] Furthermore, an antistatic agent was added to the adhesive material to reduce the peeling voltage and prevent damage to electronic devices. Chlorinated paraffin, as a liquid filler and auxiliary plasticizer, reduced viscosity and minimized internal bubbles and defects after curing. Thus, through the combination of adhesive layer raw materials, the prepared composite protective film exhibits high light transmittance, low haze, good adhesion, stable peel strength, high temperature resistance, and no adhesive residue.
[0026] 2. By introducing epoxy groups into the polyether molecular chain through the ring-opening reaction of polyether diol and epoxy monomer, crosslinking points are formed with isocyanate, which increases the crosslinking density and cohesive strength, further improves thermal stability, and also helps to improve the adhesion and bonding strength between the protective film and the substrate surface. Attached Figure Description
[0027] Figure 1 This is a schematic diagram of the composite protective film of this application.
[0028] Explanation of reference numerals in the attached figures: 1. Release layer; 2. Adhesive layer; 3. Substrate layer. Detailed Implementation
[0029] The present application will be further described in detail below with reference to Examples 1-5 and Comparative Examples 1-2. Preparation Example
[0030] Preparation Example 1-1 Preparation of organosilicon-modified diamines Add 25g of monomer octamethylcyclotetrasiloxane and 2g of end-capping agent 1,3-bis(aminopropane)tetramethyldisiloxane to a four-necked flask, start stirring and heat to 77°C, add 0.1g of tetramethylammonium hydroxide pentahydrate under a nitrogen atmosphere, and heat to 85°C to carry out ring-opening polymerization. After the viscosity of the reaction system no longer changes, the system temperature is raised to 145℃, kept at that temperature for 0.5h, and then a vacuum is drawn to remove unreacted monomers and other oligomers from the system. The system is then cooled to room temperature to obtain organosilicon-modified diamine.
[0031] Preparation Examples 1-2 Preparation of organosilicon-modified diamines Add 30g of monomer octamethylcyclotetrasiloxane and 5g of end-capping agent 1,3-bis(aminopropane)tetramethyldisiloxane to a four-necked flask, start stirring and heat to 80°C, add 0.3g of tetramethylammonium hydroxide pentahydrate under a nitrogen atmosphere, and heat to 88°C to carry out ring-opening polymerization. After the viscosity of the reaction system no longer changes, the system temperature is raised to 150°C, kept at that temperature for 1 hour, and then a vacuum is drawn to remove unreacted monomers and other oligomers from the system. The system is then cooled to room temperature to obtain organosilicon-modified diamine.
[0032] Preparation Example 2-1 Preparation of epoxy-modified polytetrahydrofuran ether diol 100g of polytetrahydrofuran ether diol was dehydrated under vacuum at 100℃ for 2h, cooled to 60℃, 7g of epichlorohydrin was added, and 0.035g of boron trifluoride ethyl ether was added dropwise. The mixture was reacted at 70℃ for 4h, neutralized, and washed with water to remove the boron trifluoride ethyl ether. The mixture was then dried under vacuum to obtain epoxy-modified polytetrahydrofuran ether diol.
[0033] Preparation Example 2-2 Preparation of epoxy-modified polytetrahydrofuran ether diol 100g of polytetrahydrofuran ether diol was dehydrated under vacuum at 120℃ for 3h, cooled to 80℃, 12g of epichlorohydrin was added, and 0.12g of boron trifluoride ethyl ether was added dropwise. The mixture was reacted at 90℃ for 6h, neutralized, and washed with water to remove the boron trifluoride ethyl ether. The mixture was then dried under vacuum to obtain epoxy-modified polytetrahydrofuran ether diol. Example
[0034] Example 1 This embodiment discloses a high-temperature resistant composite protective film, comprising a substrate layer, an adhesive layer and a release layer arranged sequentially. The substrate layer is made of PET film with a thickness of 50 μm, the release layer is made of PET release film with a thickness of 20 μm, and the adhesive layer is formed by coating with adhesive material with a thickness of 4 μm.
[0035] Adhesive materials include the following raw materials: 58g of polyurethane prepolymer; 5g of isocyanate curing agent, toluene diisocyanate is selected; 0.5g of antistatic agent, selected from octadecyl dimethyl hydroxyethyl quaternary ammonium nitrate; 1g of chlorinated paraffin; 30g of diluent, preferably 2-butanone; The polyurethane prepolymer includes the following raw materials: 80g of organosilicon-modified diamine, the organosilicon-modified diamine prepared in Preparation Example 1-1 was selected; 60g of polyether diol, specifically polytetrahydrofuran ether diol with a molecular weight of 2000; 34g of diisocyanate, selected from dicyclohexylmethane diisocyanate; 0.2g of catalyst, selected as dibutyltin dilaurate; 4g of chain extender, selected isophorone diamine; The solvent is 60g, and a mixture of 40g toluene and 20g ethyl acetate is selected.
[0036] The preparation method of the high-temperature resistant composite protective film includes the following steps: S1. Preparation of polyurethane prepolymer: The organosilicon-modified diamine was dried, and the polyether diol was dehydrated under vacuum. Then, the organosilicon-modified diamine and the polyether diol were dissolved in 30g of solvent to obtain a mixture. 30g of solvent, diisocyanate and catalyst were added to a reaction flask, stirred and heated to 55℃, and the mixture was added dropwise. The temperature was raised to 75℃ and reacted for 2h. The chain extender was added and reacted for 1.5h to obtain the polyurethane prepolymer. S2. Preparation of adhesive material: Mix polyurethane prepolymer, isocyanate curing agent, antistatic agent, chlorinated paraffin and diluent evenly to obtain adhesive material; S3. Preparation of composite protective film: The prepared adhesive material is coated on the substrate layer and baked in an oven at 120℃ for 1 minute. The thickness of the adhesive layer is controlled to be 4μm. After curing, a release film is attached to the side of the adhesive layer that is adjacent to the substrate layer. After curing in an oven at 60℃ for 24 hours, the composite protective film is obtained.
[0037] Example 2 This embodiment discloses a high-temperature resistant composite protective film, comprising a substrate layer, an adhesive layer and a release layer arranged sequentially. The substrate layer is made of PET film with a thickness of 80 μm, the release layer is made of PET release film with a thickness of 50 μm, and the adhesive layer is formed by coating with adhesive material with a thickness of 8 μm.
[0038] Adhesive materials include the following raw materials: 73g of polyurethane prepolymer; 11g of isocyanate curing agent, hexamethylene diisocyanate was selected; 2g of antistatic agent, selected from tributylmethylammonium bis(trifluoromethanesulfonyl)imide salt; 3g of chlorinated paraffin; 55g of diluent, using 30g toluene and 25g acetone; The polyurethane prepolymer includes the following raw materials: 86g of organosilicon-modified diamine, selected from the organosilicon-modified diamine prepared in Preparation Examples 1-2; 75g of polyether diol, specifically polyoxypropylene diol with a molecular weight of 2000; 38g of diisocyanate, selected from dicyclohexylmethane diisocyanate; 0.4 g of catalyst, selected as dibutyltin dilaurate; 7g of chain extender, trimethylolpropane was selected; The solvent is 80g, and a mixture of 50g toluene and 30g tetrahydrofuran is used.
[0039] The preparation method of the high-temperature resistant composite protective film includes the following steps: S1. Preparation of polyurethane prepolymer: The organosilicon-modified diamine was dried, and the polyether diol was dehydrated under vacuum. Then, the organosilicon-modified diamine and the polyether diol were dissolved in 35g of solvent to obtain a mixture. 45g of solvent, diisocyanate and catalyst were added to the reaction flask, stirred and heated to 60℃, and the mixture was added dropwise. The temperature was raised to 80℃ and reacted for 3h. The chain extender was added and reacted for 2h to obtain the polyurethane prepolymer. S2. Preparation of adhesive material: Mix polyurethane prepolymer, isocyanate curing agent, antistatic agent, chlorinated paraffin and diluent evenly to obtain adhesive material; S3. Preparation of composite protective film: The prepared adhesive material is coated on the substrate layer and baked in an oven at 125°C for 3 minutes. The thickness of the adhesive layer is controlled to be 8μm. After curing, a release film is attached to the side of the adhesive layer that is adjacent to the substrate layer. After curing in an oven at 65°C for 24 hours, the composite protective film is obtained.
[0040] Example 3 This embodiment discloses a high-temperature resistant composite protective film, comprising a substrate layer, an adhesive layer and a release layer arranged sequentially. The substrate layer is made of PET film with a thickness of 65μm, the release layer is made of PET release film with a thickness of 35μm, and the adhesive layer is formed by coating with adhesive material with a thickness of 6μm.
[0041] Adhesive materials include the following raw materials: 65g of polyurethane prepolymer; 9g of isocyanate curing agent, specifically diphenylmethane diisocyanate; 1g of antistatic agent, selected from N-methyl-N-butylpyrrolidine bis(trifluoromethanesulfonyl)imide salt; 2g of chlorinated paraffin; 45g of diluent, butyl acetate is selected; The polyurethane prepolymer includes the following raw materials: 83g of organosilicon-modified diamine, selected from the organosilicon-modified diamine prepared in Preparation Examples 1-2; 68g of polyether diol, specifically polytetrahydrofuran ether diol with a molecular weight of 2000; 35g of diisocyanate, selected from dicyclohexylmethane diisocyanate; 0.3g of catalyst, selected as dibutyltin dilaurate; 6g of chain extender, trimethylolpropane was selected; The solvent is 70g, and a mixture of 50g toluene and 30g tetrahydrofuran is used.
[0042] The preparation method of the high-temperature resistant composite protective film includes the following steps: S1. Preparation of polyurethane prepolymer: The organosilicon-modified diamine was dried, and the polyether diol was dehydrated under vacuum. Then, the organosilicon-modified diamine and the polyether diol were dissolved in 30g of solvent to obtain a mixture. 40g of solvent, diisocyanate and catalyst were added to the reaction flask, stirred and heated to 55℃, and the mixture was added dropwise. The temperature was raised to 80℃ and reacted for 2h. The chain extender was added and reacted for another 2h to obtain the polyurethane prepolymer. S2. Preparation of adhesive material: Mix polyurethane prepolymer, isocyanate curing agent, antistatic agent, chlorinated paraffin and diluent evenly to obtain adhesive material; S3. Preparation of composite protective film: The prepared adhesive material is coated on the substrate layer and baked in an oven at 120°C for 3 minutes. The thickness of the adhesive layer is controlled to be 6μm. After curing, a release film is attached to the side of the adhesive layer that is adjacent to the substrate layer. After curing in an oven at 65°C for 24 hours, the composite protective film is obtained.
[0043] Example 4 The only difference between this embodiment and Embodiment 1 is that the polyether polyol in the adhesive material is different.
[0044] In this embodiment, the polyether polyol used is the epoxy-modified polytetrahydrofuran ether diol prepared in Preparation Example 2-1.
[0045] Example 5 The only difference between this embodiment and Embodiment 1 is that the polyether polyol in the adhesive material is different.
[0046] In this embodiment, the polyether polyol used is the epoxy-modified polytetrahydrofuran ether diol prepared in Preparation Example 2-2. Comparative Example
[0047] Comparative Example 1 The only difference between this comparative example and Example 1 is that the polyurethane prepolymer in the adhesive material is different.
[0048] In this comparative example, an equal amount of polyether diol was used to replace the organosilicon-modified diamine in the raw materials of the polyurethane prepolymer, namely 140g of polytetrahydrofuran ether diol with a molecular weight of 2000.
[0049] Comparative Example 2 The only difference between this comparative example and Example 1 is the choice of adhesive material in the composite protective film.
[0050] In this comparative example, a commercially available polyurethane pressure-sensitive adhesive, Henkel brand, model 5353, was selected.
[0051] The adhesive materials and composite protective films prepared in Examples 1-5 and Comparative Examples 1-2 were tested for the following properties, and the test results are shown in Table 1.
[0052] Light transmittance: The light transmittance and haze of transparent plastics were determined by haze meter method according to GB / T 2410-2008 "Determination of light transmittance and haze of transparent plastics".
[0053] Residual adhesiveness: After applying the protective film to the glass plate, place it in an environment with a temperature of 85℃ and a humidity of 80% for 5 days. After removing the film, check whether white fog or residual adhesive appears on the glass plate.
[0054] 180° peel strength test: The test was conducted according to the method of GB / T 2792-2014 "Test method for peel strength of adhesive tape".
[0055] High temperature and high humidity 180° peel force test: Cut the prepared composite protective film into 15cm*2.5cm samples, remove the release film and stick it on the glass test plate. After placing it in an environment of 60℃ / 90%RH for 72h, take it out and place it in an environment of 23℃ / 50%RH for 2h, and retest the 180° peel force.
[0056] Table 1 Sample Light transmittance (%) Residual adhesive Peel strength (g / 25mm) High temperature and high humidity peel strength (g / 25mm) Example 1 92 No residue, no white haze 2.6 3.5 Example 2 93 No residue, no white haze 2.4 3.6 Example 3 92 No residue, no white haze 2.7 3.8 Example 4 93 No residue, no white haze 1.9 2.6 Example 5 93 No residue, no white haze 1.8 2.6 Comparative Example 1 93 White residue appeared 3.8 6.3 Comparative Example 2 92 White residue appeared 4.2 8.5 As can be seen from the data in the table, the protective film prepared in this application has good wettability, good transparency, no residue, and low peel strength. At the same time, by introducing organosilicon-modified diamine into the polyurethane prepolymer to generate urea groups with diisocyanate, the movement of molecular chains at high temperature is suppressed, which makes the high temperature resistance of the protective film better and improves the phenomenon of peel strength increase at high temperature.
[0057] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this specific embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.
Claims
1. A high-temperature resistant composite protective film, comprising a substrate layer, an adhesive layer, and a release layer arranged sequentially, characterized in that: The adhesive layer is formed by coating with an adhesive material, which includes the following raw materials in parts by weight: 58-73 parts of polyurethane prepolymer; 5-11 parts of isocyanate curing agent; 0.5-2 parts of antistatic agent; 1-3 parts of chlorinated paraffin; and 30-55 parts of diluent. The polyurethane prepolymer includes the following raw materials in parts by weight: 80-86 parts of organosilicon-modified diamine; Polyether diol 60-75 parts; diisocyanate 34-38 parts; catalyst 0.2-0.4 parts; chain extender 4-7 parts; solvent 60-80 parts; Organosilicon-modified diamines were prepared by anionic ring-opening polymerization of octamethylcyclotetrasiloxane and 1,3-bis(aminopropane)tetramethyldisiloxane.
2. The high-temperature resistant composite protective film according to claim 1, characterized in that: The organosilicon-modified diamine is prepared by the following steps: Add 25-30 parts of monomer octamethylcyclotetrasiloxane and 2-5 parts of end-capping agent 1,3-bis(aminopropane)tetramethyldisiloxane to the reactor, start stirring and heat to 77-80℃, add 0.1-0.3 parts of tetramethylammonium hydroxide pentahydrate under nitrogen atmosphere, and heat to 85-88℃ to carry out ring-opening polymerization reaction; After the viscosity of the reaction system no longer changes, the system temperature is raised to 145-150℃ and kept at that temperature for 0.5-1h. Then, a vacuum is drawn to remove unreacted monomers and other oligomers from the system. The system is then cooled to room temperature to obtain organosilicon-modified diamine.
3. The high-temperature resistant composite protective film according to claim 1, characterized in that: The polyether diol is selected from one of polytetrahydrofuran ether diol, polyoxypropylene diol, or epoxy-modified polytetrahydrofuran ether diol.
4. The high-temperature resistant composite protective film according to claim 3, characterized in that: The epoxy-modified polytetrahydrofuran ether diol was prepared through the following steps: Polytetrahydrofuran ether diol was dehydrated under vacuum at 100-120℃ for 2-3 hours, then cooled to 60-80℃. 7%-12% of epichlorohydrin by mass of polytetrahydrofuran ether diol was added, followed by the addition of 0.5%-1% of boron trifluoride diethyl ether by mass of epichlorohydrin. The mixture was reacted at 70-90℃ for 4-6 hours. After neutralization and washing with water to remove the boron trifluoride diethyl ether, the product was dried under vacuum to obtain epoxy-modified polytetrahydrofuran ether diol.
5. The high-temperature resistant composite protective film according to claim 1, characterized in that: The diisocyanate is selected from dicyclohexylmethane diisocyanate, and the catalyst is selected from dibutyltin dilaurate.
6. The high-temperature resistant composite protective film according to claim 1, characterized in that: The chain extender is selected from one or more of isophorone diamine, trimethylolpropane, and propylene glycol.
7. The high-temperature resistant composite protective film according to claim 1, characterized in that: The diluent and solvent are selected from one or more of ethyl acetate, butyl acetate, tetrahydrofuran, toluene, acetone, and butanone.
8. The high-temperature resistant composite protective film according to claim 1, characterized in that: The antistatic agent is selected from one or more of octadecyl dimethyl hydroxyethyl quaternary ammonium nitrate, tetramethyl ammonium oxalate, tributylmethyl ammonium bis(trifluoromethanesulfonyl)imide, and N-methyl-N-butylpyrrolidine bis(trifluoromethanesulfonyl)imide.
9. The high-temperature resistant composite protective film according to claim 1, characterized in that: The substrate layer is made of PET film with a thickness of 50-80μm; the release layer is made of PET release film with a thickness of 20-50μm.
10. A method for preparing a high-temperature resistant composite protective film according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Preparation of polyurethane prepolymer: The organosilicon-modified diamine is dried, and the polyether diol is dehydrated under vacuum. Then, the organosilicon-modified diamine and polyether diol are dissolved in part of the solvent to obtain a mixture. The other part of the solvent, diisocyanate and catalyst are added to the reaction flask, stirred and heated to 55-60℃, and the mixture is added dropwise. The temperature is raised to 75-80℃ and reacted for 2-3 hours. The chain extender is added and reacted for 1.5-2 hours to obtain the polyurethane prepolymer. S2. Preparation of adhesive material: Mix polyurethane prepolymer, isocyanate curing agent, antistatic agent, chlorinated paraffin and diluent evenly to obtain adhesive material; S3. Preparation of composite protective film: The prepared adhesive material is coated on the substrate layer and baked in an oven at 120-125℃ for 1-3 minutes. The thickness of the adhesive layer is controlled to be 4-8μm. After curing, a release film is attached to the side of the adhesive layer that is in contact with the substrate layer. The film is then placed in an oven at 60-65℃ for 24 hours to mature, and then removed to obtain the composite protective film.