Organic silicon pressure-sensitive adhesive as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of organic silicon pressure-sensitive adhesives, and particularly relates to a high-loss-factor organic silicon pressure-sensitive adhesive and a preparation method thereof. The organic silicon pressure-sensitive adhesive comprises a main agent component, a cross-linking agent component and a catalyst component, the main agent component is prepared from vinyl polysiloxane, polyborosiloxane, MQ resin, nano powder master batch, an inhibitor and a solvent I; according to the protective film prepared from the organic silicon pressure-sensitive adhesive, the loss factor of the prepared organic silicon pressure-sensitive adhesive can be greater than 1.3, and the maximum loss factor temperature is 10-35 DEG C, so that the organic silicon pressure-sensitive adhesive can be used for preparing protective films of precision devices and fragile products.

Description

Technical Field

[0001] The present invention belongs to the field of pressure-sensitive adhesive materials, and specifically relates to an organic silicone pressure-sensitive adhesive with a high dissipation factor (>1.3) and a maximum dissipation factor temperature of 10-35°C, as well as a preparation method and application thereof. Background Art

[0002] Pressure-sensitive adhesive (PSA) is a polymer material that achieves a strong bond with minimal pressure. Silicone PSA, based on silicone polymers, boasts excellent high and low temperature resistance, outgassing properties, and the ability to adhere to low-surface-energy substrates. It has seen rapid growth in the consumer electronics sector in recent years.

[0003] Rheology is the study of the viscoelastic properties of materials. Loss factor is a key indicator in rheology, a physical quantity that characterizes a material's ability to dissipate energy under vibration or alternating stress. Its value is equal to the ratio of energy dissipated per cycle to maximum stored energy, or the ratio of loss modulus to storage modulus. Loss factor is primarily used in the evaluation of viscoelastic material properties and in engineering vibration and noise reduction designs, directly influencing the material's dynamic response characteristics.

[0004] Pressure-sensitive adhesives (PSA) are highly viscoelastic materials with typical viscoelastic properties. In recent years, the application of silicone PSA has expanded widely. Beyond conventional process protection, end-product applications have also gradually developed. This is particularly true for the protection of precision devices or fragile finished products. Cushioning and shock absorption have become a key performance indicator for silicone PSA. A material's dissipation factor reflects its energy dissipation during vibration. A high dissipation factor indicates a material's ability to more effectively absorb and dissipate vibration energy, leading to its widespread research.

[0005] Currently, the silicone pressure-sensitive adhesives used to protect precision devices and fragile items are primarily addition-type. Testing has found that the loss factor of conventional addition-type silicone pressure-sensitive adhesives at 25°C is generally between 0.2 and 0.8, with a maximum loss factor generally ranging from 0.5 to 1.0. In practical applications, silicone pressure-sensitive adhesives used to protect precision devices and fragile items require not only excellent peel strength but also good cushioning and shock absorption properties. This means a loss factor of at least 1.2 at operating temperature is required, and for more demanding applications, even above 1.3.

[0006] Patent application publication number CN 115044084 A discloses the protective application of polyborosiloxane elastomer in display screens. However, polyborosiloxane elastomer has no adhesive properties and can only be used after being compounded with other substrates, which has certain usage restrictions. Summary of the Invention

[0007] The present invention aims to provide a high-peel-force silicone pressure-sensitive adhesive with a dissipation factor greater than 1.3 under normal operating conditions and a maximum dissipation factor temperature range of 10-35°C, and a method for preparing the adhesive. This invention addresses the aforementioned issues by adding nanomaterials and polyborosiloxane to the pressure-sensitive adhesive formulation and rationally controlling the molar ratio of the functional groups Si-H (crosslinker): Si-Vi (main agent). The resulting silicone pressure-sensitive adhesive exhibits a steel plate peel force of 1800-2500 g / 24 mm, a maximum dissipation factor greater than 1.3, and a maximum dissipation factor temperature range of 10-35°C.

[0008] The first technical problem to be solved by the present invention is to provide an organic silicone pressure-sensitive adhesive, the raw materials of which include the following components: 100 parts by weight of a main agent, 0.2-1.0 parts by weight of a cross-linking agent, and 1.0-2.0 parts by weight of a catalyst; wherein the main agent includes the following components: 100 parts by weight of vinyl polysiloxane, 30-60 parts by weight of polyborosiloxane, 180-300 parts by weight of MQ resin, 10-30 parts by weight of a nanopowder masterbatch, 0.3-1.2 parts by weight of an inhibitor, and 180-280 parts by weight of solvent I; wherein the cross-linking agent is a terminal hydrogen-based polysiloxane having a hydrogen content of 0.1-0.6 wt%; and the molar ratio of the functional group Si-H in the cross-linking agent to the functional group Si-Vi in the main agent is 1.5-6:1.

[0009] Specifically, in the above-mentioned silicone pressure-sensitive adhesive, the raw materials of the nanopowder masterbatch include the following components: 100 parts by mass of vinyl silicone oil, 20-50 parts by mass of nanopowder, 1-8 parts by mass of hexamethyldisilazane or 1-8 parts by mass of vinyl-containing silane coupling agent.

[0010] Furthermore, the nano powder is one or more of nano fumed silica, nano cerium oxide, and nano titanium oxide.

[0011] Furthermore, the vinyl silicone oil is a terminal or side-terminated vinyl silicone oil. Preferably, the vinyl content is 0.02-0.15 wt % and the viscosity is 3500-100,000 mPa.s.

[0012] Furthermore, the vinyl-containing silane coupling agent is vinyltrimethoxysilane or vinyltriethoxysilane.

[0013] Furthermore, in the above-mentioned organosilicon pressure-sensitive adhesive, the preparation method of the nanopowder masterbatch includes the following steps: mixing 100 parts by mass of vinyl silicone oil, 20-50 parts by mass of nanopowder, and 1-8 parts by mass of hexamethyldisilazane or 1-8 parts by mass of a vinyl-containing silane coupling agent at room temperature to obtain a mixture; heating the mixture to 60-100°C for reaction; then heating the mixture to 150-180°C for mixing; evacuating the mixture; and cooling and milling the mixture to obtain the nanopowder masterbatch. The reaction is performed at 60-100°C for 1-3 hours; the mixing is performed at 150-180°C for 1-3 hours; the evacuation is performed for 4-8 hours; and the mixture is further milled using a three-roll mill.

[0014] Specifically, in the above-mentioned silicone pressure-sensitive adhesive, the structural formula of the polyborosiloxane is:

[0015] .

[0016] Furthermore, in the above-mentioned organosilicon pressure-sensitive adhesive, the weight average molecular weight of the polyborosiloxane is 12,000 to 120,000. Preferably, the weight average molecular weight is 20,000 to 100,000.

[0017] Furthermore, in the above-mentioned organosilicon pressure-sensitive adhesive, the preparation method of the polyborosiloxane includes the following steps: heating a hydroxyl-terminated polysiloxane having a hydroxyl content of 0.05-0.5 wt% (preferably 0.2 wt%) to 110-140°C (preferably 120°C), adding boric acid, stirring, heating to 130-160°C (preferably 145-160°C, more preferably 150°C) for reaction with stirring, and cooling to obtain the polyborosiloxane; wherein the molar ratio of the hydroxyl-terminated polysiloxane to the boric acid is 0.75-1.25:1. Preferably, the addition of the boric acid is stirred for 10-30 minutes, and the temperature is raised to 130-160°C for reaction with stirring for 1-2 hours.

[0018] Specifically, in the above-mentioned organosilicon pressure-sensitive adhesive, the vinyl polysiloxane is a terminal vinyl polysiloxane. Preferably, the vinyl content is 0.02-0.2 wt% and the molecular weight is 80,000-700,000. More preferably, the vinyl content is 0.02-0.12 wt% and the molecular weight is 200,000-650,000.

[0019] Specifically, in the above-mentioned organosilicon pressure-sensitive adhesive, the MQ resin is a methyl MQ resin. Preferably, the MQ resin has an M / Q ratio of 0.7 to 1.0 and a weight-average molecular weight of 4000 to 7000.

[0020] Specifically, in the above-mentioned silicone pressure-sensitive adhesive, the inhibitor is at least one of methyl butynol, ethynyl cyclohexanol, propynol, phenyl ethynol, hexynol, dimethyl heptynol, diphenyl propynol or methyl dodecynol.

[0021] Specifically, in the above-mentioned organosilicon pressure-sensitive adhesive, the solvent I is at least one of toluene, xylene, ethyl acetate or solvent gasoline.

[0022] Specifically, the preparation method of the main agent in the above-mentioned silicone pressure-sensitive adhesive includes the following steps: mixing vinyl polysiloxane, polyborosiloxane, MQ resin, nanopowder masterbatch, and solvent I at 60-100°C, cooling to below 50°C, adding an inhibitor, and mixing to obtain the main agent. Furthermore, the mixing is performed at 60-100°C for 3-6 hours. The inhibitor is then added and mixed for 1-3 hours.

[0023] Specifically, in the above-mentioned organosilicon pressure-sensitive adhesive, the catalyst is a platinum catalyst. Further, the catalyst is a Custer platinum catalyst with a platinum content of 4000 to 6000 ppm.

[0024] Specifically, in the above-mentioned silicone pressure-sensitive adhesive, the crosslinking agent is a terminal hydrogen-based polysiloxane having a hydrogen content of 0.2 to 0.6 wt%.

[0025] Furthermore, in the above-mentioned silicone pressure-sensitive adhesive, the molar ratio of the functional group Si-H in the cross-linking agent (hydrogen polysiloxane) to the functional group Si-Vi in the main agent (vinyl polysiloxane and vinyl silicone oil) is 2 to 6:1.

[0026] The second technical problem to be solved by the present invention is to provide a method for preparing the aforementioned organosilicon pressure-sensitive adhesive. This method comprises the following steps: taking 100 parts by weight of the main agent, diluting it with 0 to 100 parts by weight of solvent II, then adding 0.2 to 1.0 parts by weight of a crosslinker and mixing uniformly, and then adding 1.0 to 2.0 parts by weight of a catalyst and mixing uniformly, to produce the organosilicon pressure-sensitive adhesive. Whether to add solvent II is determined based on the viscosity.

[0027] Preferably, in the preparation method of the above-mentioned organosilicon pressure-sensitive adhesive, the solvent II is at least one of ethyl acetate, toluene, xylene, n-heptane, butanone, and solvent gasoline.

[0028] Preferably, in the preparation method of the above-mentioned organosilicon pressure-sensitive adhesive, the cross-linking agent is added and mixed for 5 to 10 minutes.

[0029] Preferably, in the preparation method of the above-mentioned organosilicon pressure-sensitive adhesive, the catalyst is added and mixed for 10 to 30 minutes.

[0030] The third technical problem to be solved by the present invention is to provide a protective film prepared from the above-mentioned silicone pressure-sensitive adhesive. The protective film is used to protect precision devices or fragile items, such as chips and mobile phone glass screens.

[0031] The fourth technical problem to be solved by the present invention is to provide a method for preparing the above-mentioned protective film. The preparation method comprises the following steps: uniformly coating the silicone pressure-sensitive adhesive on a fluoroplastic release film, then placing the fluoroplastic release film coated with the silicone pressure-sensitive adhesive at 50-80°C, then curing it at 150-180°C, removing it, and then attaching a fluoroplastic film to the surface of the pressure-sensitive adhesive to form a protective film. The 50-80°C temperature is maintained for 5-10 minutes. The 150-180°C temperature is used for curing for 5-10 minutes. Preferably, the dry adhesive thickness of the pressure-sensitive adhesive layer after curing on the fluoroplastic film is 120-130 μm.

[0032] The present invention adds nanomaterials and polyborosiloxane to the pressure-sensitive adhesive formula, and preferably controls the molar ratio of the functional group Si-H of the hydrogen polysiloxane in the cross-linking agent to the functional group Si-Vi in the vinyl polysiloxane in the main agent and the vinyl silicone oil, so that the obtained organic silicone pressure-sensitive adhesive has a steel plate peeling force of 1800-2500 g / 24 mm, a maximum loss factor of more than 1.3, and a temperature of the maximum loss factor within the range of 10-35°C. DETAILED DESCRIPTION

[0033] The present invention provides a method for preparing a high dissipation factor organosilicon pressure-sensitive adhesive protective film, comprising the following steps:

[0034] (1) Preparation of nanopowder masterbatch: 100 parts by mass of vinyl silicone oil, 20-50 parts by mass of nanopowder, 1-8 parts by mass of hexamethyldisilazane or 1-8 parts by mass of vinyl-containing silane coupling agent are mixed at room temperature to obtain a mixture; the mixture is heated to 60-100°C for reaction for 1-3 hours, then heated to 150-180°C for mixing for 1-3 hours, and vacuumed for 4-8 hours; after cooling, the mixture is ground with a three-roll mill to obtain a nanopowder masterbatch;

[0035] (2) Preparation of the main agent: vinyl polysiloxane, polyborosiloxane, MQ resin, nanopowder masterbatch and solvent I are mixed at 60-100°C for 3-6 hours, then cooled to below 50°C, an inhibitor is added, and mixed for 1-3 hours to obtain the main agent; wherein, the preparation method of the polyborosiloxane comprises the following steps: 1000g of 107 glue (hydroxy polysiloxane) with a hydroxyl content of 0.2wt% is added into a planetary stirred tank, stirring is started, the temperature is raised to 120°C, 0.36g of boric acid is added in three portions, the temperature is continued to be raised to 150°C and stirred for 1 hour, and the polyborosiloxane is obtained by cooling;

[0036] (3) Preparation of pressure-sensitive adhesive: Take 100 parts by weight of the main agent, add 0-100 parts by weight of solvent II to dilute, then add 0.2-1.0 parts by weight of the cross-linking agent, mix for 5-10 minutes; then add 1.0-2.0 parts by weight of the catalyst, mix for 10-30 minutes, and the silicone pressure-sensitive adhesive is obtained;

[0037] (4) Pressure-sensitive adhesive coating and curing: The obtained silicone pressure-sensitive adhesive is evenly coated on the fluoroplastic release film, and then the fluoroplastic release film coated with the silicone pressure-sensitive adhesive is placed at 50-80°C for 5-10 minutes, and then cured at 150-180°C for 5-10 minutes. After taking it out, another layer of fluoroplastic release film is attached to the surface of the pressure-sensitive adhesive to form a protective film.

[0038] The present invention adds nanopowder to the pressure-sensitive adhesive formula, which can improve the loss factor of the pressure-sensitive adhesive after curing within a certain range, while having a minimal impact on the peel force of the pressure-sensitive adhesive from the steel plate. Furthermore, preparing the nanopowder into a nanopowder masterbatch can improve the dispersibility of the nanopowder in the pressure-sensitive adhesive, thereby improving the stability and coating properties of the pressure-sensitive adhesive.

[0039] The present invention adds polyborosiloxane to the pressure-sensitive adhesive formulation. Because the terminal hydroxyl groups in its molecular chain can form dynamic hydrogen bonds with the borohydroxyl groups, the addition of polyborosiloxane can improve the loss factor of the pressure-sensitive adhesive under various shear conditions. Furthermore, controlling the polyborosiloxane content can ensure the pressure-sensitive adhesive's coatability and peel strength.

[0040] To ensure efficient curing, conventional pressure-sensitive adhesives typically incorporate hydrogen-based polysiloxanes with a high hydrogen content (greater than 1.0%). However, high hydrogen-based polysiloxanes increase the maximum dissipation factor temperature of the pressure-sensitive adhesive and decrease the dissipation factor. However, reducing the hydrogen content of the hydrogen-based polysiloxane slows the curing speed. The present invention utilizes end-side hydrogen-based polysiloxanes with a lower hydrogen content as a crosslinker, further improving the dissipation factor while ensuring a high curing speed. Furthermore, the molar ratio of the functional groups Si-H (crosslinker) to Si-Vi (main agent) in the pressure-sensitive adhesive is controlled to ensure stable peel force.

[0041] In the formulation of the present invention, both the nanopowder masterbatch and the polyborosiloxane can improve the maximum loss factor, but will increase the maximum loss factor temperature. However, the hydrogen-based polysiloxane with a lower hydrogen group content can significantly reduce the maximum loss factor temperature. The synergistic effect of the three makes the silicone pressure-sensitive adhesive obtained by the present invention have good performance.

[0042] The following detailed examples illustrate the preparation and application of the silicone pressure-sensitive adhesive of the present invention. Each example utilizes a silicone pressure-sensitive adhesive comprising a base component, a crosslinker component, and a catalyst component. In each example, unless otherwise specified, all parts are by weight. The vinyl polysiloxane is either a high-temperature adhesive (110-1 or 110-0) produced by Dongjue Silicone or a vinyl-terminated silicone oil produced by Tuoli Technology. The nanopowder is A200 fumed silica produced by Evonik. The vinyl silicone oil is a vinyl-terminated polysiloxane produced by Tuoli Technology. The catalyst is Heraeus Pt-5000, all of which are commercially available products.

[0043] Example 1

[0044] (1) Preparation of nanopowder masterbatch: 100 parts by mass of vinyl-terminated silicone oil with a viscosity of 15,000 and a vinyl content of 0.08%, 30 parts by mass of nano-silica, and 5 parts by mass of hexamethyldisilazane were mixed at room temperature to obtain a mixture; the mixture was heated to 60°C for reaction for 1 hour, then heated to 150°C for mixing for 3 hours, and vacuumed for 4 hours; after cooling, the mixture was ground with a three-roll mill to obtain a nanopowder masterbatch.

[0045] (2) Preparation of the main agent: 100 parts by weight of high-temperature adhesive 110-0 with a molecular weight of 550,000 and a vinyl content of 0.03%, 45 parts by weight of polyborosiloxane, 250 parts by weight of MQ resin, 25 parts by weight of nanopowder masterbatch and 200 parts by weight of toluene were mixed at 60°C for 6 hours, then cooled to below 50°C, 0.4 parts by weight of ethynyl cyclohexanol was added and mixed for 3 hours to prepare the main agent;

[0046] (3) Preparation of pressure-sensitive adhesive: Take 100 parts by weight of the main agent, add 40 parts by weight of ethyl acetate to dilute it, then add 0.65 parts by weight of a cross-linking agent (a terminal hydrogen-based polysiloxane with a hydrogen content of 0.25 wt%) (Si-H:Si-Vi=6:1), and mix for 10 minutes; then add 1.0 parts by weight of the catalyst component and mix for 30 minutes to prepare a silicone pressure-sensitive adhesive.

[0047] (4) Pressure-sensitive adhesive coating and curing: The above-obtained silicone pressure-sensitive adhesive is evenly coated on the fluoroplastic release film, and the fluoroplastic release film coated with the silicone pressure-sensitive adhesive is placed at 70°C for 5 minutes, and then cured at 150°C for 10 minutes. After taking it out, another layer of fluoroplastic release film is attached to the surface of the pressure-sensitive adhesive to form a protective film.

[0048] (5) Performance test: Test the steel plate peeling force, maximum loss factor and maximum loss factor temperature. Specific performance parameters are shown in Table 1.

[0049] Example 2

[0050] (1) Preparation of nanopowder masterbatch: same as in Example 1;

[0051] (2) Preparation of the main agent: 100 parts by weight of end-side vinyl silicone oil with a molecular weight of 150,000 and a vinyl content of 0.06%, 60 parts by weight of polyborosiloxane, 300 parts by weight of MQ resin, 10 parts by weight of nanopowder masterbatch and 190 parts by weight of ethyl acetate were mixed at 60°C for 3 hours, then cooled to below 50°C, 1.2 parts by weight of methylbutynol was added and mixed for 2 hours to prepare the main agent.

[0052] (3) Preparation of pressure-sensitive adhesive: Take 100 parts by weight of the main agent, add 50 parts by weight of toluene to dilute it, then add 0.21 parts by weight of a cross-linking agent (a terminal hydrogen-based polysiloxane with a hydrogen content of 0.4 wt%) (Si-H:Si-Vi=2:1), and mix for 10 minutes; then add 1.0 parts by weight of the catalyst component and mix for 20 minutes to prepare a silicone pressure-sensitive adhesive.

[0053] (4) Pressure-sensitive adhesive coating and curing: The above-obtained silicone pressure-sensitive adhesive is evenly coated on the fluoroplastic release film, and the fluoroplastic release film coated with the silicone pressure-sensitive adhesive is placed at 60°C for 10 minutes, and then cured at 180°C for 10 minutes. After taking it out, another layer of fluoroplastic release film is attached to the surface of the pressure-sensitive adhesive to form a protective film.

[0054] (5) Performance test: Test the steel plate peeling force, maximum loss factor and maximum loss factor temperature. Specific performance parameters are shown in Table 1.

[0055] Example 3

[0056] (1) Preparation of nanopowder masterbatch: 100 parts by mass of end-side vinyl silicone oil with a viscosity of 100,000 and a vinyl content of 0.04%, 20 parts by mass of nano-silica, and 8 parts by mass of hexamethyldisilazane were mixed at room temperature to obtain a mixture; the mixture was heated to 100°C for reaction for 1 hour, then heated to 150°C for mixing for 3 hours, and vacuumed for 6 hours; after cooling, the mixture was ground with a three-roll mill to obtain a nanopowder masterbatch.

[0057] (2) Preparation of the main agent: 100 parts by weight of high-temperature adhesive 110-0 with a molecular weight of 600,000 and a vinyl content of 0.04%, 60 parts by weight of polyborosiloxane, 300 parts by weight of MQ resin, 20 parts by weight of nanopowder masterbatch and 250 parts by weight of solvent gasoline were mixed at 60°C for 5 hours, then cooled to below 50°C, 0.8 parts by weight of ethynyl cyclohexanol was added and mixed for 3 hours to obtain the main agent.

[0058] (3) Preparation of pressure-sensitive adhesive: Take 100 parts by weight of the main agent, add 50 parts by weight of ethyl acetate to dilute it, then add 0.30 parts by weight of a cross-linking agent (a terminal hydrogen-based polysiloxane with a hydrogen content of 0.4 wt%) (Si-H:Si-Vi=5:1), and mix for 5 minutes; then add 2.0 parts by weight of the catalyst component and mix for 10 minutes to prepare the silicone pressure-sensitive adhesive.

[0059] (4) Pressure-sensitive adhesive coating and curing: The above-obtained silicone pressure-sensitive adhesive is evenly coated on the fluoroplastic release film, and the fluoroplastic release film coated with the silicone pressure-sensitive adhesive is placed at 80°C for 10 minutes, and then cured at 160°C for 10 minutes. After taking it out, another layer of fluoroplastic release film is attached to the surface of the pressure-sensitive adhesive to form a protective film.

[0060] (5) Performance test: Test the steel plate peeling force, maximum loss factor and maximum loss factor temperature. Specific performance parameters are shown in Table 1.

[0061] Example 4

[0062] (1) Preparation of nanopowder masterbatch: same as in Example 3;

[0063] (2) Preparation of the main agent: 100 parts by weight of end-side vinyl silicone oil with a molecular weight of 100,000 and a vinyl content of 0.12%, 40 parts by weight of polyborosiloxane, 250 parts by weight of MQ resin, 20 parts by weight of nanopowder masterbatch and 180 parts by weight of solvent gasoline were mixed at 60°C for 5 hours, then cooled to below 50°C, 1.0 part by weight of hexynol was added and mixed for 2 hours to prepare the main agent.

[0064] (3) Preparation of pressure-sensitive adhesive: Take 100 parts by weight of the main agent, add 50 parts by weight of ethyl acetate to dilute it, then add 0.80 parts by weight of a cross-linking agent (a terminal hydrogen-based polysiloxane with a hydrogen content of 0.5 wt%) (Si-H:Si-Vi=5:1), and mix for 5 minutes; then add 1.5 parts by weight of a catalyst and mix for 30 minutes to obtain a silicone pressure-sensitive adhesive.

[0065] (4) Pressure-sensitive adhesive coating and curing: The above-obtained silicone pressure-sensitive adhesive is evenly coated on the fluoroplastic release film, and the fluoroplastic release film coated with the silicone pressure-sensitive adhesive is placed at 80°C for 10 minutes, and then cured at 160°C for 10 minutes. After taking it out, another layer of fluoroplastic release film is attached to the surface of the pressure-sensitive adhesive to form a protective film.

[0066] (5) Performance test: Test the steel plate peeling force, maximum loss factor and maximum loss factor temperature. Specific performance parameters are shown in Table 1.

[0067] Example 5

[0068] (1) Preparation of nanopowder masterbatch: same as in Example 1;

[0069] (2) Preparation of the main agent: 100 parts by weight of end-side vinyl silicone oil with a molecular weight of 150,000 and a vinyl content of 0.1%, 50 parts by weight of polyborosiloxane, 280 parts by weight of MQ resin, 20 parts by weight of nanopowder masterbatch and 200 parts by weight of solvent gasoline were mixed at 60°C for 5 hours, then cooled to below 50°C, 0.2 parts by weight of ethynyl cyclohexanol and 0.8 parts by weight of methyl butynol were added and mixed for 3 hours to prepare the main agent.

[0070] (3) Preparation of pressure-sensitive adhesive: 100 parts by weight of the main agent was added with 60 parts by weight of ethyl acetate for dilution, and then 0.96 parts by weight of a cross-linking agent (a terminal hydrogen-based polysiloxane with a hydrogen content of 0.4 wt%) (Si-H:Si-Vi=6:1) was added and mixed for 5 minutes; then 1.8 parts by weight of the catalyst component was added and mixed for 20 minutes to obtain a silicone pressure-sensitive adhesive.

[0071] (4) Pressure-sensitive adhesive coating and curing: The above-obtained silicone pressure-sensitive adhesive is evenly coated on the fluoroplastic release film, and the fluoroplastic release film coated with the silicone pressure-sensitive adhesive is placed at 70°C for 10 minutes, and then cured at 150°C for 10 minutes. After taking it out, another layer of fluoroplastic release film is attached to the surface of the pressure-sensitive adhesive to form a protective film.

[0072] (5) Performance test: Test the steel plate peeling force, maximum loss factor and maximum loss factor temperature. Specific performance parameters are shown in Table 1.

[0073] Comparative Example 1

[0074] (1) Preparation of the main agent: 100 parts by weight of high temperature adhesive 110-0, 60 parts by weight of polyborosiloxane, 300 parts by weight of MQ resin and toluene were mixed at 60°C for 6 hours, then cooled to below 50°C, ethynyl cyclohexanol was added and mixed for 3 hours to prepare the main agent.

[0075] (2) Preparation of pressure-sensitive adhesive: same as in Example 1

[0076] (3) Pressure-sensitive adhesive coating and curing: Same as Example 1

[0077] (4) Performance test: Same as Example 1

[0078] Comparative Example 2

[0079] (1) Preparation of nanopowder masterbatch: same as in Example 1;

[0080] (2) Preparation of the main agent: 100 parts by weight of end-side vinyl silicone oil with a molecular weight of 150,000 and a vinyl content of 0.1%, 300 parts by weight of MQ resin, 10 parts by weight of nanopowder masterbatch and 120 parts by weight of ethyl acetate were mixed at 60°C for 3 hours, then cooled to below 50°C, 1.2 parts by weight of methylbutynol were added and mixed for 2 hours to prepare the main agent.

[0081] (3) Preparation of pressure-sensitive adhesive: same as in Example 2.

[0082] (4) Pressure-sensitive adhesive coating and curing: same as in Example 2.

[0083] (5) Performance test: Same as Example 2.

[0084] Comparative Example 3

[0085] (1) Preparation of polyborosiloxane II: same as in Example 1;

[0086] (2) Preparation of the main agent: same as in Example 4.

[0087] (3) Preparation of pressure-sensitive adhesive: Take 100 parts by weight of the main agent, add 50 parts by weight of ethyl acetate to dilute it, then add 1.2 parts by weight of the crosslinker component (1.6 wt% of pendant hydrogen polysiloxane), mix for 5 minutes; then add 1.5 parts by weight of the catalyst, mix for 20 minutes, and the silicone pressure-sensitive adhesive is obtained.

[0088] (4) Pressure-sensitive adhesive coating and curing: same as in Example 4.

[0089] (5) Performance test: Same as Example 4.

[0090] Comparative Example 4

[0091] (1) Preparation of nanopowder masterbatch: same as in Example 3;

[0092] (2) Preparation of the main agent: 100 parts by weight of high-temperature adhesive 110-0 with a molecular weight of 600,000 and a vinyl content of 0.04%, 80 parts by weight of polyborosiloxane, 300 parts by weight of MQ resin, 20 parts by weight of nanopowder masterbatch and 250 parts by weight of solvent gasoline were mixed at 60°C for 5 hours, then cooled to below 50°C, 0.8 parts by weight of ethynyl cyclohexanol was added and mixed for 3 hours to obtain the main agent.

[0093] (3) Preparation of pressure-sensitive adhesive: same as in Example 3.

[0094] (4) Pressure-sensitive adhesive coating and curing: same as in Example 3.

[0095] (5) Performance test: Same as Example 3.

[0096] Table 1 Performance test results of examples and comparative examples

[0097] Performance indicators Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Steel plate peeling force g / 24mm 1850 2100 2400 1870 1950 2200 2500 2600 1500 Maximum loss factor 1.32 1.37 1.47 1.33 1.38 1.21 1.25 1.20 1.47 Maximum loss factor temperature ℃ 25.3 34.2 34.7 27 25.4 18.7 25 45 51.4

[0098] The performance test standards and methods of the above-mentioned silicone pressure-sensitive adhesive are as follows:

[0099] Steel plate peeling strength: refer to the test method of 180° peeling strength in GB / T2792, and select mirror steel plate as the test plate.

[0100] Furthermore, the test method for the peeling force of the steel plate is: tear off the fluoroplastic release film on one side of the protective film, stick the adhesive side on the 50μm PET film, then tear off the other side of the fluoroplastic release film, stick it on the steel plate, and test the peeling force of the steel plate.

[0101] Loss factor: tested using a rheometer (test parameters: temperature = -10°C ~ 100°C; heating rate = 5°C / min; strain = 0.1%; f = 1Hz; F = 1N)

[0102] Furthermore, the loss factor test method is as follows: tear off the fluoroplastic release film on one side of two protective films, put the adhesive sides together, repeat this process, stack eight layers, and make the stacked thickness 950-1050mm. The test is performed using a rheometer (test parameters: temperature = -10°C to 100°C; heating rate = 5°C / min; strain = 0.1%; f = 1Hz; F = 1N).

[0103] It can be seen from the data of Examples 1-5 in the table that, within the defined range of the present invention, the steel plate peeling force, maximum loss factor, and maximum loss factor temperature all meet the index requirements.

[0104] The data from the Examples and Comparative Examples in the table show that, compared to Example 1, Comparative Example 1, which simply eliminated the nanopowder masterbatch, significantly reduced the maximum loss factor. Compared to Example 2, Comparative Example 2, which simply eliminated the polyborosiloxane, also significantly reduced the maximum loss factor. Compared to Example 4, Comparative Example 3, which simply replaced the crosslinker with a high-hydrogen polysiloxane, saw the maximum loss factor temperature rise to 45°C. Compared to Example 3, Comparative Example 4, which simply increased the amount of polyborosiloxane, significantly reduced the steel plate peel force and increased the maximum loss factor temperature.

Claims

1. A silicone pressure-sensitive adhesive, characterized in that: The raw materials include the following components: 100 parts by weight of a main agent, 0.2-1.0 parts by weight of a cross-linking agent, and 1.0-2.0 parts by weight of a catalyst; wherein the main agent includes the following components: 100 parts by weight of vinyl polysiloxane, 30-60 parts by weight of polyborosiloxane, 180-300 parts by weight of MQ resin, 10-30 parts by weight of a nanopowder masterbatch, 0.3-1.2 parts by weight of an inhibitor, and 180-280 parts by weight of solvent I; wherein the cross-linking agent is a terminal hydrogen-based polysiloxane having a hydrogen content of 0.1-0.6 wt%; and the molar ratio of the functional group Si-H in the cross-linking agent to the functional group Si-Vi in the main agent is 1.5-6:

1.

2. The organosilicon pressure-sensitive adhesive according to claim 1, characterized in that: The raw materials of the nano powder masterbatch include the following components: 100 parts by mass of vinyl silicone oil, 20 to 50 parts by mass of nano powder, 1 to 8 parts by mass of hexamethyldisilazane or 1 to 8 parts by mass of a vinyl-containing silane coupling agent; Furthermore, the nano powder is one or more of nano fumed silica, nano cerium oxide, and nano titanium oxide; Furthermore, the vinyl silicone oil is a terminal or side vinyl silicone oil; preferably, the vinyl content is 0.02-0.15 wt % and the viscosity is 3500-100,000 mPa.s; Furthermore, the vinyl-containing silane coupling agent is vinyltrimethoxysilane or vinyltriethoxysilane; Furthermore, the preparation method of the nanopowder masterbatch includes the following steps: mixing 100 parts by mass of vinyl silicone oil, 20 to 50 parts by mass of nanopowder, 1 to 8 parts by mass of hexamethyldisilazane or 1 to 8 parts by mass of a vinyl-containing silane coupling agent at room temperature to obtain a mixture, heating the mixture to 60 to 100°C for reaction, then heating it to 150 to 180°C for mixing, vacuuming, cooling and grinding to obtain a nanopowder masterbatch; further, reacting at 60 to 100°C for 1 to 3 hours; mixing at 150 to 180°C for 1 to 3 hours; and vacuuming for 4 to 8 hours.

3. The organosilicon pressure-sensitive adhesive according to claim 1 or 2, characterized in that: The structural formula of the polyborosiloxane is: , weight average molecular weight is 12000~120000; Furthermore, the preparation method of the polyborosiloxane comprises the following steps: heating a hydroxyl-terminated polysiloxane having a hydroxyl content of 0.05 to 0.5 wt% to 110 to 140° C., preferably 120° C., adding boric acid, stirring, heating to 130 to 160° C., preferably 145 to 160° C., more preferably 150° C., stirring for reaction, and cooling to obtain polyborosiloxane; wherein the molar ratio of the hydroxyl-terminated polysiloxane to boric acid is 0.75 to 1.25:1; preferably, adding boric acid and stirring for 10 to 30 minutes; heating to 130 to 160° C. and stirring for reaction for 1 to 2 hours.

4. The organosilicon pressure-sensitive adhesive according to any one of claims 1 to 3, characterized in that: At least one of the following is met: The vinyl polysiloxane is a terminal vinyl polysiloxane; preferably, the vinyl content is 0.02-0.2 wt % and the molecular weight is 80,000-700,000; more preferably, the vinyl content is 0.02-0.12 wt % and the molecular weight is 200,000-650,000; The MQ resin is a methyl MQ resin; preferably, the MQ resin has an M / Q ratio of 0.7 to 1.0 and a weight average molecular weight of 4000 to 7000; The inhibitor is at least one of methylbutynol, ethynylcyclohexanol, propynol, phenylacetynol, hexynol, dimethylheptynol, diphenylpropynol or methyldodecynol; The solvent I is at least one of toluene, xylene, ethyl acetate or solvent gasoline.

5. The organosilicon pressure-sensitive adhesive according to any one of claims 1 to 4, characterized in that: The preparation method of the main agent comprises the following steps: mixing vinyl polysiloxane, polyborosiloxane, MQ resin, nano powder masterbatch and solvent I at 60-100° C., cooling to below 50° C., adding an inhibitor, and mixing to obtain the main agent; further, mixing at 60-100° C. for 3-6 hours; and adding the inhibitor and mixing for 1-3 hours.

6. The organosilicon pressure-sensitive adhesive according to any one of claims 1 to 5, characterized in that: The catalyst is a platinum catalyst; further, the catalyst is a Custer platinum catalyst with a platinum content of 4000 to 6000 ppm.

7. The organosilicon pressure-sensitive adhesive according to any one of claims 1 to 6, characterized in that: The crosslinking agent is a terminal hydrogen-based polysiloxane with a hydrogen content of 0.2 to 0.6 wt %. The molar ratio of the functional group Si-H in the crosslinking agent to the functional group Si-Vi in the main agent is 2 to 6:

1.

8. The method for preparing the organosilicon pressure-sensitive adhesive according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: taking 100 parts by weight of a main agent, adding 0 to 100 parts by weight of a solvent II to dilute the mixture, then adding 0.2 to 1.0 parts by weight of a cross-linking agent and mixing the mixture, and then adding 1.0 to 2.0 parts by weight of a catalyst and mixing the mixture to obtain the organosilicon pressure-sensitive adhesive; preferably, in the preparation method of the organosilicon pressure-sensitive adhesive, the solvent II is at least one of ethyl acetate, toluene, xylene, n-heptane, butanone, and solvent gasoline.

9. A protective film prepared from the organosilicon pressure-sensitive adhesive according to any one of claims 1 to 7.

10. The method for preparing the protective film according to claim 9, characterized in that: The following steps are involved: The silicone pressure-sensitive adhesive according to any one of claims 1 to 7 or the silicone pressure-sensitive adhesive prepared according to claim 8 is evenly coated on a fluoroplastic release film, and then the fluoroplastic release film coated with the silicone pressure-sensitive adhesive is placed at 50-80°C, and then placed at 150-180°C for curing. After taking it out, a fluoroplastic film is attached to the surface of the pressure-sensitive adhesive to prepare a protective film; preferably, the 50-80°C placement is performed for 5-10 minutes; the 150-180°C curing is performed for 5-10 minutes; preferably, the dry adhesive thickness of the pressure-sensitive adhesive layer after curing on the fluoroplastic film is 120-130 μm.

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