A silicone pressure-sensitive adhesive composition and use thereof

Abstract

This invention provides an organosilicon pressure-sensitive adhesive composition and its application. The composition comprises methyl vinyl silicone rubber raw material and methyl MQ resin. The methyl vinyl silicone rubber raw material includes methyl vinyl silicone rubber raw material X and methyl vinyl silicone rubber raw material Y. The vinyl content of methyl vinyl silicone rubber raw material X is 0.03–0.05%, and the vinyl content of methyl vinyl silicone rubber raw material Y is 0.18–0.25%. The methyl MQ resin includes methyl MQ resin A and methyl MQ resin B. The weight-average molecular weight of methyl MQ resin A is 7000–9000, and the weight-average molecular weight of methyl MQ resin B is 14000–16000. This organosilicon pressure-sensitive adhesive composition exhibits high peel strength to low surface energy materials and low adhesion to high surface energy materials (steel plates), which is beneficial for die-cutting processes.

Description

Technical Field

[0001] This application belongs to the field of organosilicon pressure-sensitive adhesive technology, and relates to organosilicon pressure-sensitive adhesive compositions, and more particularly to a pressure-sensitive adhesive composition and its preparation method and application. Background Technology

[0002] Silicone pressure-sensitive adhesives are a new type of high-performance adhesive. Compared to other types of pressure-sensitive adhesives such as acrylic and rubber-based adhesives, they possess some unique and irreplaceable properties, such as stable adhesion, excellent resistance to high and low temperatures, chemical corrosion resistance, and low permeability. Furthermore, they exhibit good adhesion to low surface energy materials, such as anti-fingerprint glass (AF glass), polytetrafluoroethylene (PTFE), and polyimide (PI). It is precisely because of the excellent adhesion of silicone pressure-sensitive films to low surface energy materials that they have been widely used in the field of protective films, such as mobile phone screen protectors, electronic device protective films, and lithium battery protective films.

[0003] However, traditional silicone pressure-sensitive adhesives exhibit the same peel force trend for both low surface energy materials and high surface energy materials (such as steel plates). It is difficult to achieve high adhesion to low surface energy materials when the adhesion to steel plates is low, which is not conducive to die-cutting.

[0004] Chinese patent CN108531126A discloses a boron-modified silicone pressure-sensitive adhesive. By adding boron, the adhesive's adhesion to low surface energy silicone rubber is improved. However, this method can only simultaneously improve the adhesive's peel force to silicone rubber and its adhesion to steel plates, but it cannot reduce the adhesion to steel plates.

[0005] Therefore, how to improve the adhesion of pressure-sensitive adhesives to low surface energy materials while ensuring low adhesion to high surface energy materials is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] To address the above deficiencies, this invention provides an organosilicon pressure-sensitive adhesive composition that exhibits high peel strength to low surface energy materials and low adhesion to high surface energy materials (such as standard steel plates), which is beneficial for die-cutting processes.

[0007] The present invention also provides an organosilicon pressure-sensitive adhesive film, comprising the above-mentioned organosilicon pressure-sensitive adhesive composition, which can be used for surface protection of low surface energy materials to achieve stable and high peel force, while having low adhesion to high surface energy materials (such as standard steel plates), which is beneficial for die-cutting processing.

[0008] The first aspect of the present invention provides an organosilicon pressure-sensitive adhesive composition comprising methyl vinyl silicone rubber raw rubber and methyl MQ resin;

[0009] The methyl vinyl silicone rubber raw material includes methyl vinyl silicone rubber raw material X and methyl vinyl silicone rubber raw material Y; the vinyl content in methyl vinyl silicone rubber raw material X is 0.03-0.05%, and the vinyl content in methyl vinyl silicone rubber raw material Y is 0.18-0.25%.

[0010] The methyl MQ resin includes methyl MQ resin A and methyl MQ resin B, wherein the weight-average molecular weight of methyl MQ resin A is 7000-9000 and the weight-average molecular weight of methyl MQ resin B is 14000-16000.

[0011] In the organosilicon pressure-sensitive adhesive described above, the mass ratio of the methyl vinyl silicone rubber raw rubber to the methyl MQ resin is 100:(100-200).

[0012] The silicone pressure-sensitive adhesive as described above, wherein the mass ratio of the methyl vinyl silicone rubber raw material X and the methyl vinyl silicone rubber raw material Y is (20:80) to (80:20);

[0013] And / or, the mass ratio of the methyl MQ resin A and methyl MQ resin B is (30:70) to (70:30).

[0014] The organosilicon pressure-sensitive adhesive as described above, wherein the weight-average molecular weight of the methyl vinyl silicone rubber raw rubber is 400,000 to 800,000;

[0015] And / or, the hydroxyl content of the methyl MQ resin is 0.5% to 1.5%.

[0016] The silicone pressure-sensitive adhesive as described above, wherein the silicone pressure-sensitive adhesive composition further includes polyether silicone oil;

[0017] Preferably, the mass ratio of polyether silicone oil to the methyl vinyl silicone rubber raw rubber is (1-10):100;

[0018] Preferably, the viscosity of the polyether silicone oil is 1000-3000 cP; more preferably, the viscosity of the polyether silicone oil is 1500-2000 cP.

[0019] The silicone pressure-sensitive adhesive as described above further includes a solvent, wherein the solvent includes at least one of aromatic hydrocarbon solvents, ester solvents, alkane solvents, and ketone solvents;

[0020] Preferably, the solvent includes at least one of toluene, xylene, ethyl acetate, butanone, heptane, and No. 120 solvent oil;

[0021] Preferably, the mass ratio of the solvent to the methyl vinyl silicone rubber raw rubber is (100-400):100.

[0022] The silicone pressure-sensitive adhesive as described above, wherein the silicone pressure-sensitive adhesive composition further includes a hydrosilicone crosslinking agent and / or an inhibitor;

[0023] Preferably, the mass ratio of the hydrosilicone crosslinking agent to the methyl vinyl silicone rubber raw rubber is (0.5-3.0):100, and / or the mass ratio of the inhibitor to the methyl vinyl silicone rubber raw rubber is (0.5-2.0):100.

[0024] In the silicone pressure-sensitive adhesive described above, the viscosity of the silane crosslinking agent is 10-50 cP and the hydrogen content is 1.0-1.6%.

[0025] The silicone pressure-sensitive adhesive as described above, wherein the inhibitor comprises alkynyl alcohol compounds and / or silane compounds;

[0026] Preferably, the inhibitor comprises at least one of tetramethyltetravinylcyclotetrasiloxane, tetramethyldivinyldisiloxane, dimethylethynol, methylbutynol, 3,5-dimethyl-1-hexynyl-3-ol, and 3-methyl-1-dodecynyl-3-ol.

[0027] A second aspect of the present invention provides an organosilicon pressure-sensitive adhesive film, the organosilicon pressure-sensitive adhesive film comprising a substrate and an adhesive layer in contact with each other, the adhesive layer being obtained by heat curing the organosilicon pressure-sensitive adhesive composition described in the first aspect.

[0028] The silicone pressure-sensitive adhesive composition of the present invention includes two different MQ resins and two different methyl vinyl silicone rubber raw materials. By controlling the vinyl content in the two methyl vinyl silicone rubber raw materials and the molecular weight of the two methyl MQ resins, the components can work synergistically to achieve high peel force of the silicone pressure-sensitive adhesive on low surface energy materials, while having low peel force on high surface energy materials (such as standard steel plates). Detailed Implementation

[0029] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below. The specific embodiments listed below are merely descriptions of the principles and features of the present invention, and the examples are only for explaining the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Silicone pressure-sensitive adhesives are products made by condensing raw silicone rubber and MQ resin. They are pressure-sensitive, achieving adhesion under slight pressure, and possess excellent adhesion, chemical resistance, water resistance, oil resistance, solvent resistance, high and low temperature resistance, and oxidative degradation resistance. They are suitable for various surface treatments, such as fingerprint glass (AF glass), polytetrafluoroethylene (PTFE), and polyimide (PI). However, traditional silicone pressure-sensitive adhesives generally exhibit a positive correlation between their adhesion to low and high surface energy materials; that is, while they possess high peel strength to low surface energy materials, they generally also possess high peel strength to high surface energy materials, which is detrimental to die-cutting processes.

[0031] Through analysis, the inventors discovered that the formation of peel force mainly depends on the wettability of the pressure-sensitive adhesive to the surface of the substrate. Good wettability helps to form mechanical interlocking forces and intermolecular forces between the pressure-sensitive adhesive and the substrate, and wettability is closely related to the crosslinking density of the pressure-sensitive adhesive. Therefore, the inventors attempted to construct a crosslinking network by combining methyl vinyl silicone rubber raw materials with different vinyl contents, and achieved differentiated bonding effects on different substrates (high surface energy materials and low surface energy materials) by doping with methyl MQ resin of different molecular weights.

[0032] Based on the above analysis, the first aspect of the present invention provides an organosilicon pressure-sensitive adhesive composition, comprising methyl vinyl silicone rubber raw rubber and methyl MQ resin;

[0033] Methyl vinyl silicone rubber raw materials include methyl vinyl silicone rubber raw material X and methyl vinyl silicone rubber raw material Y; the vinyl content in methyl vinyl silicone rubber raw material X is 0.03-0.05%, and the vinyl content in methyl vinyl silicone rubber raw material Y is 0.18-0.25%.

[0034] Methyl MQ resins include methyl MQ resin A and methyl MQ resin B. The weight-average molecular weight of methyl MQ resin A is 7,000 to 9,000, and the weight-average molecular weight of methyl MQ resin B is 14,000 to 16,000.

[0035] In this invention, "methyl MQ resin" refers to a novel organosilicon polymer material whose molecules have a three-dimensional (non-linear) structure with Si-O bonds as the backbone.

[0036] This invention does not specifically limit the type and source of methyl vinyl silicone rubber raw materials. Commercially available products or products prepared by conventional methods well known to those skilled in the art can be used. It is only necessary to ensure that the vinyl content in methyl vinyl silicone rubber raw material X is 0.03-0.05% and the vinyl content in methyl vinyl silicone rubber raw material Y is 0.18-0.25%.

[0037] This invention does not specifically limit the type and source of methyl MQ resin. Commercially available products or products prepared by conventional methods well known to those skilled in the art can be used. It is only necessary to ensure that the weight average molecular weight of methyl MQ resin A is 7000-9000 and the weight average molecular weight of methyl MQ resin B is 14000-16000.

[0038] For example, the vinyl content in methyl vinyl silicone rubber raw material X is 0.03%, 0.035%, 0.04%, 0.045%, or 0.05%; the vinyl content in methyl vinyl silicone rubber raw material Y is 0.18%, 0.19%, 0.20%, 0.21%, 0.22%, 0.23%, 0.24%, or 0.25%.

[0039] For example, the weight-average molecular weight of methyl MQ resin A is 7000, 7200, 7400, 7600, 7800, 8000, 8200, 8400, 8600, 8800 or 9000; and the weight-average molecular weight of methyl MQ resin B is 14000, 14200, 14400, 14600, 14800, 15000, 15200, 15400, 15600, 15800 or 16000.

[0040] The silicone pressure-sensitive adhesive composition of this invention comprises two MQ resins with different weight-average molecular weights. The high-molecular-weight methyl MQ resin B (weight-average molecular weight 14,000–16,000) has high cohesive strength and excellent reinforcing effect, thus significantly increasing the film strength and improving the peel force of the pressure-sensitive adhesive on low surface energy materials. However, the poor compatibility between the high-molecular-weight methyl MQ resin and methyl vinyl silicone rubber raw material significantly reduces the wettability of the silicone pressure-sensitive adhesive composition on low surface energy materials, negatively impacting the peel force. By adding a low-molecular-weight methyl MQ resin A (weight-average molecular weight 7,000–9,000), the compatibility between methyl MQ resin A and the system can be improved. Under pressure, this results in better microscopic wetting and flowability, enhancing the wetting effect of the pressure-sensitive adhesive on low surface energy materials and forming a more stable mechanical interlocking force, thereby improving the peel force on the surface of low surface energy materials. Furthermore, the low-molecular-weight methyl MQ resin B, due to its lower degree of polymerization, can reduce the peel force of the pressure-sensitive adhesive on high surface energy materials to a certain extent. Meanwhile, methyl vinyl silicone rubber raw material (vinyl content 0.03–0.05%) X can form a cross-linked network structure with methyl vinyl silicone rubber raw material Y (vinyl content 0.18–0.25%), binding the two methyl MQ resins within it. This not only further enhances the compatibility of the two methyl MQ resins with the system but also creates a good reinforcing and tackifying effect, further improving the peel strength of the silicone pressure-sensitive adhesive composition to low surface energy materials. Furthermore, due to its higher vinyl content, methyl vinyl silicone rubber raw material Y (vinyl content 0.18–0.25%) can increase the cross-linking density of the system to some extent, reducing the system's fluidity and consequently decreasing the wettability of the silicone pressure-sensitive adhesive to high surface energy materials, thus reducing the peel strength to high surface energy materials.

[0041] Therefore, the silicone pressure-sensitive adhesive composition of the present invention can exhibit high adhesion to low surface energy materials while ensuring low adhesion to high surface energy materials, and can be widely used in the field of protective films.

[0042] In this invention, low surface energy materials refer to materials with a water contact angle ≥ 90°, and high surface energy materials refer to materials with a water contact angle < 90°. The "water contact angle" can be measured using a contact angle measuring instrument according to the standard ASTM D7334-08.

[0043] Furthermore, in order to improve the adhesion to low surface energy materials while ensuring low adhesion to high surface energy materials, it is necessary to control the mass ratio of methyl vinyl silicone rubber raw rubber to methyl MQ resin, the mass ratio of methyl vinyl silicone rubber raw rubber X to methyl vinyl silicone rubber raw rubber Y, and the mass ratio of methyl MQ resin A to methyl MQ resin B.

[0044] In one specific embodiment, the mass ratio of methyl vinyl silicone rubber raw rubber to methyl MQ resin is 100:(100-200). Within this range, the peel force of the pressure-sensitive adhesive on low surface energy materials can be further improved while ensuring low peel force on high surface energy materials.

[0045] For example, the mass ratio of methyl vinyl silicone rubber raw rubber to methyl MQ resin is 100:100, 100:120, 100:140, 100:160, 100:180 or 100:200.

[0046] In one specific embodiment, the mass ratio of methyl vinyl silicone rubber raw material X to methyl vinyl silicone rubber raw material Y is (20:80) to (80:20). When there is too much methyl vinyl silicone rubber raw material X, the adhesive layer of the silicone pressure-sensitive adhesive becomes too soft, resulting in higher adhesion to high surface energy materials. Conversely, when there is too much methyl vinyl silicone rubber raw material Y, the adhesive layer of the silicone pressure-sensitive adhesive becomes too hard, reducing adhesion to both low and high surface energy materials. Within this range, the content of methyl vinyl silicone rubber raw material X and methyl vinyl silicone rubber raw material Y is suitable, ensuring low peel strength to high surface energy materials while also improving the peel strength of the pressure-sensitive adhesive to low surface energy materials.

[0047] For example, the mass ratio of methyl vinyl silicone rubber raw material X and methyl vinyl silicone rubber raw material Y is 20:80, 30:70, 40:60, 50:50, 60:40, 70:30 or 80:20.

[0048] In one specific embodiment, the mass ratio of methyl MQ resin A to methyl MQ resin B is (30:70) to (70:30). Excessive methyl MQ resin A can decrease the adhesion of the silicone pressure-sensitive adhesive to both low and high surface energy materials; excessive methyl MQ resin B can not only worsen the system's compatibility but also result in excessively high adhesion to high surface energy materials. Within this range, the amount of both resins is appropriate, achieving both low adhesion to high surface energy materials and improved adhesion to low surface energy materials.

[0049] For example, the mass ratio of methyl MQ resin A to methyl MQ resin B is 30:70, 40:60, 50:50, 60:40, or 70:30.

[0050] Furthermore, the molecular weight of the methyl vinyl silicone rubber raw material and the hydroxyl content of the methyl MQ resin have a certain influence on the adhesion and wettability of the organosilicon pressure-sensitive adhesive composition. Therefore, it is necessary to control the molecular weight of the methyl vinyl silicone rubber raw material and the hydroxyl content of the methyl MQ resin.

[0051] In one specific embodiment, the weight-average molecular weight of the methyl vinyl silicone rubber raw material is 400,000 to 800,000. Within this range, a suitable crosslinking density can be formed. The crosslinking density is directly related to the wettability of the composition system on the substrate. The wettability needs to be maintained within a suitable range to avoid excessive wettability leading to increased peel force on high surface energy materials, and insufficient wettability leading to decreased peel force on low surface energy materials. Therefore, when the weight-average molecular weight of the methyl vinyl silicone rubber raw material is within the aforementioned range, high adhesion to low surface energy materials can be guaranteed, while low adhesion to high surface energy materials can be achieved.

[0052] For example, the molecular weight of methyl vinyl silicone rubber raw rubber is 400,000, 450,000, 500,000, 550,000, 600,000, 650,000, 700,000, 750,000 or 800,000.

[0053] In one specific embodiment, the hydroxyl content of the methyl MQ resin is 0.5% to 1.5%. The hydroxyl content of the methyl MQ resin affects the cohesive strength of the silicone pressure-sensitive adhesive, and consequently its adhesion to low surface energy materials. Within this range, the hydroxyl content of the methyl MQ resin is suitable, as it not only allows the silicone pressure-sensitive adhesive to have lower peel strength to high surface energy materials, but also further improves its peel strength to low surface energy materials.

[0054] For example, the hydroxyl content of the methyl MQ resin is 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, or 1.5%.

[0055] Furthermore, to further enhance the adhesion of the silicone pressure-sensitive adhesive, polyether silicone oil can be added to the composition. The polyether segments in the polyether silicone oil can form more hydrogen bonds with the surface of the substrate, effectively improving the adhesion between the pressure-sensitive adhesive and low surface energy materials. In addition, the entanglement of polyether segments in the polyether silicone oil can improve the precipitation of small molecules in the silicone oil system of the pressure-sensitive adhesive, reducing the white haze on the surface of small molecules caused by the precipitation of small molecules in the silicone system under high temperature and high humidity conditions.

[0056] In one specific embodiment, the silicone pressure-sensitive adhesive composition further includes polyether silicone oil;

[0057] Preferably, the mass ratio of polyether silicone oil to methyl vinyl silicone rubber raw rubber is (1-10):100;

[0058] Preferably, the viscosity of the polyether silicone oil is 1000-3000 cP; more preferably, the viscosity of the polyether silicone oil is 1500-2000 cP.

[0059] When the silicone pressure-sensitive adhesive composition includes polyether silicone oil, and the mass ratio of polyether silicone oil to methyl vinyl silicone rubber raw rubber is within the aforementioned range, it can effectively improve the adhesion of the pressure-sensitive adhesive to low surface energy materials, and ensure the adhesion to high surface energy materials. At the same time, it can also improve the precipitation of small silicone oil molecules.

[0060] Furthermore, when the viscosity of the polyether silicone oil is within the aforementioned range, it can be better compatible with the organosilicon pressure-sensitive adhesive composition system.

[0061] For example, the mass ratio of polyether silicone oil to methyl vinyl silicone rubber raw rubber is 1:100, 2:100, 4:100, 6:100, 8:100 or 10:100.

[0062] For example, the viscosity of the polyether silicone oil is 1000 cP, 1200 cP, 1400 cP, 1600 cP, 1800 cP, 2000 cP, 2200 cP, 2400 cP, 2600 cP, 2800 cP or 3000 cP.

[0063] Furthermore, in order to better dissolve the active ingredients in the silicone pressure-sensitive adhesive composition and obtain a pressure-sensitive adhesive with stable quality and excellent performance, the silicone pressure-sensitive adhesive composition also needs to include a solvent.

[0064] In one specific embodiment, the silicone pressure-sensitive adhesive composition further includes a solvent, which includes at least one of aromatic hydrocarbon solvents, ester solvents, alkane solvents, and ketone solvents;

[0065] Preferably, the solvent includes at least one of toluene, xylene, ethyl acetate, butanone, heptane, and No. 120 solvent oil;

[0066] Preferably, the mass ratio of solvent to methyl vinyl silicone rubber raw rubber is (100-400):100.

[0067] When the solvent includes the aforementioned compounds, the active ingredients in the silicone pressure-sensitive adhesive composition can be dissolved well, which helps to obtain a pressure-sensitive adhesive with stable quality and excellent performance.

[0068] The mass fraction of solvent in the silicone pressure-sensitive adhesive composition directly affects the solid content of the adhesive. Too low or too high a solid content will result in excessively low or high viscosity, both of which are detrimental to its use. When the mass fraction of solvent is within the aforementioned range, the solid content of the adhesive is suitable, achieving high adhesion.

[0069] For example, the solvent in the silicone pressure-sensitive adhesive composition is in the mass fractions of 100:100, 160:100, 220:100, 280:100, 340:100 or 400:100.

[0070] Furthermore, the silicone pressure-sensitive adhesive composition may also include some additives, such as crosslinking agents and inhibitors. Among them, crosslinking agents can crosslink and cure the molecules in the pressure-sensitive adhesive, and prevent the pressure-sensitive adhesive from decomposing and failing at high temperatures, thereby enhancing the adhesive strength and improving its heat resistance; inhibitors can reduce the chemical reaction rate between the components in the silicone pressure-sensitive adhesive composition, effectively extending the service life of the silicone pressure-sensitive adhesive bath.

[0071] In one specific embodiment, the silicone pressure-sensitive adhesive composition further includes a hydrosilicone crosslinking agent and / or an inhibitor;

[0072] Preferably, the mass ratio of the hydrosilicone crosslinking agent to the methyl vinyl silicone rubber raw rubber is (0.5-3.0):100; and the mass ratio of the inhibitor to the methyl vinyl silicone rubber raw rubber is (0.5-2.0):100.

[0073] In detail, the silicone pressure-sensitive adhesive composition further includes a hydrosilicone crosslinking agent, or the silicone pressure-sensitive adhesive composition further includes an inhibitor, or the silicone pressure-sensitive adhesive composition further includes both a hydrosilicone crosslinking agent and an inhibitor.

[0074] When the silicone pressure-sensitive adhesive composition includes the aforementioned substances and the mass fraction of the pressure-sensitive adhesive composition is within the aforementioned range, the peeling force of the silicone pressure-sensitive adhesive on low surface energy materials can be further improved.

[0075] For example, the mass ratio of the hydrosilicone crosslinking agent to the methyl vinyl silicone rubber raw rubber is 0.5:100, 1.0:100, 1.5:100, 2.0:100, 2.5:100, or 3.0:100; the mass ratio of the inhibitor to the methyl vinyl silicone rubber raw rubber is 0.5:100, 1.0:100, 1.5:100, or 2.0:100.

[0076] In one specific embodiment, the viscosity of the silane crosslinking agent is 10-50 cP and the hydrogen content is 1.0-1.6%.

[0077] When the viscosity and hydrogen content of the silane crosslinking agent are within the aforementioned range, the silicone pressure-sensitive adhesive can achieve a good curing effect.

[0078] For example, the viscosity of the hydrosilicone crosslinking agent is 10 cP, 20 cP, 30 cP, 40 cP or 50 cP; and the hydrogen content is 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5% or 1.6%.

[0079] In one specific embodiment, the inhibitor includes alkynyl alcohols and / or silane compounds;

[0080] Preferably, the inhibitor comprises at least one of tetramethyltetravinylcyclotetrasiloxane, tetramethyldivinyldisiloxane, dimethylethynol, methylbutynol, 3,5-dimethyl-1-hexynyl-3-ol, and 3-methyl-1-dodecynyl-3-ol.

[0081] When the aforementioned compounds are used as inhibitors, the service life of the diluted pressure-sensitive adhesive can be extended, resulting in better application.

[0082] This invention does not limit the preparation method of the silicone pressure-sensitive adhesive composition, and it can be prepared by conventional methods in the art. In one embodiment, it can be prepared by a method including the following steps:

[0083] Methyl vinyl silicone rubber raw material X, methyl vinyl silicone rubber raw material Y, methyl MQ resin A, methyl MQ resin B, polyether silicone oil and solvent are uniformly mixed and heated to dissolve; then an inhibitor and a silane crosslinking agent are added to the dissolved mixture and uniformly dispersed to obtain an organosilicon pressure-sensitive adhesive composition.

[0084] This invention does not impose specific limitations on the dissolution temperature and time; suitable dissolution conditions can be selected according to actual conditions. For example, the dissolution temperature is 60–120°C, and the time is 4–8 hours; preferably, the dissolution temperature is 70–100°C, and the time is 5–7 hours.

[0085] This invention does not impose a specific limit on the dispersion time; a suitable dispersion time can be selected based on the actual situation. For example, the dispersion time can be 4 to 8 hours.

[0086] A second aspect of the present invention provides a silicone pressure-sensitive adhesive film comprising a substrate and an adhesive layer in contact with each other, the adhesive layer being obtained by heat curing the silicone pressure-sensitive adhesive composition of the first aspect. Therefore, this silicone pressure-sensitive adhesive film exhibits high peel strength to low surface energy materials and low peel strength to high surface energy materials.

[0087] This invention does not limit the selection of substrates and may use common substrates in the art, such as PET film, polytetrafluoroethylene film, polyimide film, etc.

[0088] This invention does not specifically limit the preparation method of the organosilicon pressure-sensitive film, which can be prepared by conventional methods in the art. In one embodiment, it can be prepared by the following method:

[0089] The silicone pressure-sensitive adhesive composition is uniformly mixed with a caster platinum catalyst (platinum content 1000-5000ppm), wherein the mass ratio of the silicone pressure-sensitive adhesive composition to the caster platinum catalyst is 100:(1-5), to obtain a mixed solution; the aforementioned mixed solution is coated on the surface of a substrate and cured at a temperature of 140-160℃ for 1.5-3 minutes to obtain a pressure-sensitive adhesive protective film.

[0090] The organosilicon pressure-sensitive adhesive composition provided by the present invention will be described in detail below with reference to specific embodiments.

[0091] Example 1

[0092] 1) Mix 160 parts by weight of xylene, 30 parts by weight of methyl vinyl silicone rubber raw material X (vinyl content 0.03%, weight average molecular weight 400,000), 70 parts by weight of methyl vinyl silicone rubber raw material Y (vinyl content 0.18%, weight average molecular weight 600,000), 50 parts by weight of methyl MQ resin A (weight average molecular weight 7,000, hydroxyl content 0.8%), 90 parts by weight of methyl MQ resin B (weight average molecular weight 16,000, hydroxyl content 1.0%), and 2 parts by weight of polyether silicone oil (viscosity 1200 cP), and heat to 80°C for 4 hours to dissolve, to obtain a mixed system;

[0093] 2) Add 1.8 parts by weight of the inhibitor methylethynol and 1.5 parts by weight of the silane crosslinking agent (viscosity 10 cP, hydrogen content 1.6%) to the above-mentioned mixture system, and disperse for 1 hour to obtain the organosilicon pressure-sensitive adhesive composition of this embodiment.

[0094] Example 2

[0095] 1) Mix 167 parts by weight of xylene, 50 parts by weight of methyl vinyl silicone rubber raw material X (vinyl content 0.04%, weight average molecular weight 600,000), 50 parts by weight of methyl vinyl silicone rubber raw material Y (vinyl content 0.20%, weight average molecular weight 800,000), 75 parts by weight of methyl MQ resin A (weight average molecular weight 8,000, hydroxyl content 1.0%), 75 parts by weight of methyl MQ resin B (weight average molecular weight 16,000, hydroxyl content 1.5%), and 2 parts by weight of polyether silicone oil (viscosity 2500 cP), heat to 100℃ for 8 hours to dissolve, and obtain a mixed system;

[0096] 2) Add 1.8 parts by weight of the inhibitor methylethynol and 1.5 parts by weight of the silane crosslinking agent (viscosity 20 cP, hydrogen content 1.6%) to the above-mentioned mixture system, and disperse for 1 hour to obtain the organosilicon pressure-sensitive adhesive composition of this embodiment.

[0097] Example 3

[0098] 1) Mix 173 parts by weight of toluene, 50 parts by weight of methyl vinyl silicone rubber raw material X (vinyl content 0.05%, weight average molecular weight 700,000), 50 parts by weight of methyl vinyl silicone rubber raw material Y (vinyl content 0.24%, weight average molecular weight 500,000), 90 parts by weight of methyl MQ resin A (weight average molecular weight 9,000, hydroxyl content 1.2%), 70 parts by weight of methyl MQ resin B (weight average molecular weight 15,000, hydroxyl content 1.2%), and 8 parts by weight of polyether silicone oil (viscosity 2200 cP), heat to 80°C for 6 hours to dissolve, and obtain a mixed system;

[0099] 2) Add 1.2 parts by mass of the inhibitor tetramethyltetravinylcyclotetrasiloxane and 2 parts by mass of the silane crosslinking agent (viscosity 40 cP, hydrogen content 1.2%) to the above-mentioned mixture system, and disperse for 1 hour to obtain the organosilicon pressure-sensitive adhesive composition of this embodiment.

[0100] Example 4

[0101] 1) Mix 167 parts by weight of toluene, 70 parts by weight of methyl vinyl silicone rubber raw material X (vinyl content 0.05%, weight average molecular weight 700,000), 30 parts by weight of methyl vinyl silicone rubber raw material Y (vinyl content 0.25%, weight average molecular weight 750,000), 60 parts by weight of methyl MQ resin A (weight average molecular weight 7,000, hydroxyl content 0.9%), 90 parts by weight of methyl MQ resin B (weight average molecular weight 15,000, hydroxyl content 1.1%), and 5 parts by weight of polyether silicone oil (viscosity 1200 cP), heat to 90°C for 6 hours to dissolve, and obtain a mixed system;

[0102] 2) Add 0.8 parts by mass of the inhibitor tetramethyltetravinylcyclotetrasiloxane and 2 parts by mass of the silane crosslinking agent (viscosity 40 cP, hydrogen content 1.2%) to the above-mentioned mixture system, and disperse for 1 hour to obtain the organosilicon pressure-sensitive adhesive composition of this embodiment.

[0103] Example 5

[0104] The silicone pressure-sensitive adhesive in this embodiment is basically the same as that in Example 1, except that in step 1), methyl MQ resin A is 29 parts by mass and methyl MQ resin B is 51 parts by mass.

[0105] Example 6

[0106] The silicone pressure-sensitive adhesive in this embodiment is basically the same as that in Example 1, except that in step 1), the raw methyl vinyl silicone rubber X is 15 parts by weight and the raw methyl vinyl silicone rubber Y is 85 parts by weight.

[0107] Example 7

[0108] The silicone pressure-sensitive adhesive in this embodiment is basically the same as that in Example 1, except that in step 1), methyl MQ resin A is 35 parts by mass and methyl MQ resin B is 105 parts by mass.

[0109] Example 8

[0110] The silicone pressure-sensitive adhesive in this embodiment is basically the same as that in Example 1, except that in step 1), the hydroxyl content of methyl MQ resin B is 2.0%.

[0111] Example 9

[0112] The silicone pressure-sensitive adhesive in this embodiment is basically the same as that in Example 1, except that polyether silicone oil was not added in step 1).

[0113] Example 10

[0114] The silicone pressure-sensitive adhesive in this embodiment is basically the same as that in Example 1, except that the viscosity of the polyether silicone oil in step 1) is 500 cP.

[0115] Comparative Example 1

[0116] 1) Mix 160 parts by weight of xylene, 100 parts by weight of methyl vinyl silicone rubber raw rubber X (vinyl content 0.03%, weight average molecular weight 400,000), 140 parts by weight of methyl MQ resin A (weight average molecular weight 7,000, hydroxyl content 0.8%), and 2 parts by weight of polyether silicone oil (viscosity 1200 cP), heat to 80°C for 4 hours to dissolve, and obtain a mixed system;

[0117] 2) Add 1.8 parts by weight of the inhibitor methylethynol and 1.5 parts by weight of the silane crosslinking agent (viscosity 10 cP, hydrogen content 1.6%) to the above-mentioned mixture system, and disperse for 1 hour to obtain the organosilicon pressure-sensitive adhesive composition of this embodiment.

[0118] Comparative Example 2

[0119] 1) Mix 160 parts by weight of xylene, 100 parts by weight of methyl vinyl silicone rubber raw rubber Y (vinyl content 0.18%, weight average molecular weight 600,000), 140 parts by weight of methyl MQ resin B (weight average molecular weight 16,000, hydroxyl content 1.0%), and 2 parts by weight of polyether silicone oil (viscosity 1200 cP), heat to 80°C for 4 hours to dissolve, and obtain a mixed system;

[0120] 2) Add 1.8 parts by weight of the inhibitor methylethynol and 1.5 parts by weight of the silane crosslinking agent (viscosity 10 cP, hydrogen content 1.6%) to the above-mentioned mixture system, and disperse for 1 hour to obtain the organosilicon pressure-sensitive adhesive composition of this embodiment.

[0121] Comparative Example 3

[0122] 1) Mix 160 parts by weight of xylene, 100 parts by weight of methyl vinyl silicone rubber raw rubber X (vinyl content 0.03%, weight average molecular weight 400,000), 140 parts by weight of methyl MQ resin B (weight average molecular weight 16,000, hydroxyl content 1.0%), and 2 parts by weight of polyether silicone oil (viscosity 1200 cP), heat to 80°C for 4 hours to dissolve, and obtain a mixed system;

[0123] 2) Add 1.8 parts by weight of the inhibitor methylethynol and 1.5 parts by weight of the silane crosslinking agent (viscosity 10 cP, hydrogen content 1.6%) to the above-mentioned mixture system, and disperse for 1 hour to obtain the organosilicon pressure-sensitive adhesive composition of this embodiment.

[0124] Comparative Example 4

[0125] 1) Mix 160 parts by weight of xylene, 100 parts by weight of methyl vinyl silicone rubber raw rubber Y (vinyl content 0.18%, weight average molecular weight 600,000), 140 parts by weight of methyl MQ resin A (weight average molecular weight 7,000, hydroxyl content 0.8%), and 2 parts by weight of polyether silicone oil (viscosity 1200 cP), heat to 80°C for 4 hours to dissolve, and obtain a mixed system;

[0126] 2) Add 1.8 parts by weight of the inhibitor methylethynol and 1.5 parts by weight of the silane crosslinking agent (viscosity 10 cP, hydrogen content 1.6%) to the above-mentioned mixture system, and disperse for 1 hour to obtain the organosilicon pressure-sensitive adhesive composition of this embodiment.

[0127] Test case

[0128] 1. The silicone pressure-sensitive adhesive composition prepared in the above examples and comparative examples is uniformly mixed with a platinum catalyst (platinum content 5000ppm). The mass ratio of the silicone pressure-sensitive adhesive composition to the platinum catalyst is 100:1 to obtain a mixed solution. The mixed solution is coated on a 50μm PET film and cured at 150℃ for 2min to obtain a silicone pressure-sensitive adhesive film with a dry adhesive thickness of 10μm. The film is then cut to a width of 25mm to obtain a pressure-sensitive adhesive tape.

[0129] The properties of the pressure-sensitive adhesive tape prepared above were tested:

[0130] 1) Adhesion strength testing method

[0131] The adhesion strength of the pressure-sensitive adhesive tape prepared above to steel plate, AF glass and PTFE was tested respectively, and the unit was gf; the test method was in accordance with GB / T 2792-1998, and the test equipment was Kejian KJ1065A.

[0132] 2) PET film surface tension test

[0133] The pressure-sensitive adhesive tape prepared above was bonded to a high surface tension PET film (surface dyn value 44), and stored in a high temperature and high humidity environment (85℃, 85%RH) for 3 days. The tape was then removed, and the dyn value of the bonded PET film surface was tested using a dyn pen, with the unit being dyn / cm.

[0134] 3) High temperature and high humidity aging test for glass

[0135] The pressure-sensitive adhesive tape prepared above was applied to AF glass and stored in a high temperature and high humidity (85℃, 85%RH) environment for 7 days. The tape was then removed, and the glass surface was observed for any white fog.

[0136] The test results are shown in Table 1.

[0137] Table 1

[0138]

[0139]

[0140] As shown in Table 2:

[0141] Compared to Comparative Examples 1-4, the pressure-sensitive adhesive tape prepared from the silicone pressure-sensitive adhesive compositions of Examples 1-10 exhibits better overall performance, ensuring low adhesion to high surface energy materials while maintaining high adhesion to low surface energy materials. Specifically, the pressure-sensitive adhesive tape in Example 1 shows low adhesion to steel plates (731 gf) but high adhesion to PTFE in AF glass (31 gf for AF glass and 38 gf for PTFE), with a dyn value of 38 dyn / cm for the PET film adhered to the surface. Furthermore, no white haze was observed on the AF glass surface after high-temperature and high-humidity aging treatment. Therefore, the present invention can improve the adhesion of pressure-sensitive adhesive to low surface energy materials while maintaining low adhesion to high surface energy materials.

[0142] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A silicone pressure-sensitive adhesive composition, characterized in that, Including methyl vinyl silicone rubber raw rubber and methyl MQ resin; The methyl vinyl silicone rubber raw material includes methyl vinyl silicone rubber raw material X and methyl vinyl silicone rubber raw material Y; the vinyl content in methyl vinyl silicone rubber raw material X is 0.03-0.05%, and the vinyl content in methyl vinyl silicone rubber raw material Y is 0.18-0.25%. The methyl MQ resin includes methyl MQ resin A and methyl MQ resin B, wherein the weight-average molecular weight of methyl MQ resin A is 7000-9000 and the weight-average molecular weight of methyl MQ resin B is 14000-16000.

2. The organosilicon pressure-sensitive adhesive composition according to claim 1, characterized in that, The mass ratio of the methyl vinyl silicone rubber raw rubber to the methyl MQ resin is 100:(100-200).

3. The silicone pressure-sensitive adhesive composition according to claim 1 or 2, characterized in that, The mass ratio of the methyl vinyl silicone rubber raw material X and the methyl vinyl silicone rubber raw material Y is (20:80) to (80:20); And / or, the mass ratio of the methyl MQ resin A and methyl MQ resin B is (30:70) to (70:30).

4. The organosilicon pressure-sensitive adhesive composition according to any one of claims 1-3, characterized in that, The weight-average molecular weight of the methyl vinyl silicone rubber raw rubber is 400,000 to 800,000. And / or, the hydroxyl content of the methyl MQ resin is 0.5% to 1.5%.

5. The silicone pressure-sensitive adhesive composition according to any one of claims 1-4, characterized in that, The organosilicon pressure-sensitive adhesive composition also includes polyether silicone oil; Preferably, the mass ratio of the polyether silicone oil to the methyl vinyl silicone rubber raw rubber is (1-10):100; Preferably, the viscosity of the polyether silicone oil is 1000-3000 cP; more preferably, the viscosity of the polyether silicone oil is 1500-2000 cP.

6. The silicone pressure-sensitive adhesive composition according to any one of claims 1-5, characterized in that, The silicone pressure-sensitive adhesive composition further includes a solvent, which includes at least one of aromatic hydrocarbon solvents, ester solvents, alkane solvents, and ketone solvents; Preferably, the solvent includes at least one of toluene, xylene, ethyl acetate, butanone, heptane, and No. 120 solvent oil; Preferably, the mass ratio of the solvent to the methyl vinyl silicone rubber raw rubber is (100-400):

100.

7. The silicone pressure-sensitive adhesive composition according to any one of claims 1-6, characterized in that, The silicone pressure-sensitive adhesive composition further includes a silane crosslinking agent and / or an inhibitor; Preferably, the mass ratio of the hydrosilicone crosslinking agent to the methyl vinyl silicone rubber raw rubber is (0.5-3.0):100, and / or the mass ratio of the inhibitor to the methyl vinyl silicone rubber raw rubber is (0.5-2.0):

100.

8. The silicone pressure-sensitive adhesive composition according to claim 7, characterized in that, The viscosity of the silane crosslinking agent is 10-50 cP, and the hydrogen content is 1.0-1.6%.

9. The silicone pressure-sensitive adhesive composition according to claim 7 or 8, characterized in that, The inhibitors include alkynyl alcohols and / or silane compounds; Preferably, the inhibitor comprises at least one of tetramethyltetravinylcyclotetrasiloxane, tetramethyldivinyldisiloxane, dimethylethynol, methylbutynol, 3,5-dimethyl-1-hexynyl-3-ol, and 3-methyl-1-dodecynyl-3-ol.

10. An organosilicon pressure-sensitive adhesive film, characterized in that, The silicone pressure-sensitive adhesive film comprises a substrate and an adhesive layer in contact with each other, wherein the adhesive layer is obtained by heat curing the silicone pressure-sensitive adhesive composition according to any one of claims 1-9.

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