Self-repairing silicone resin, preparation method thereof, OCA optical adhesive containing the same and application thereof

Abstract

The application provides a self-repairing silicone resin and a preparation method thereof, OCA optical glue containing the self-repairing silicone resin and application of the self-repairing silicone resin. The self-repairing silicone resin contains a disulfide bond and a mercapto group in a molecular structure. The content of the disulfide bond in the self-repairing silicone resin is greater than 0.6 mmol / g. The self-repairing silicone resin is used for preparing OCA optical glue. While ensuring high light transmittance, low yellowing and good mechanical properties of the OCA optical glue, the self-repairing silicone resin can improve the initial adhesion of the OCA optical glue, and can also endow the OCA optical glue with a self-repairing function and improve the repair efficiency.

Description

Technical Field

[0001] This invention belongs to the field of optical materials technology, specifically relating to a self-healing silicone resin and its preparation method, an OCA optical adhesive containing the same and its applications. Background Technology

[0002] OCA (Optical Clear Adhesive) is a substrate-free, solid, double-sided adhesive tape with a release film layer bonded to both the top and bottom layers. It is a type of pressure-sensitive adhesive. OCA is widely used in the optical display field, such as for bonding display modules, glass covers, touch screens, and other display units. It features high light transmittance and good bonding strength.

[0003] Currently, OCA optical adhesives can be categorized based on the materials used, including acrylate OCA, silicone OCA, polyurethane OCA, and epoxy resin OCA. Compared to the other types of OCA, silicone OCA offers superior weather resistance, resistance to yellowing and aging, and ease of repair. However, silicone OCA generally suffers from poor initial tack, with peel strength significantly lower than other resins. This low initial tack prevents immediate transfer after bonding, leading to low production efficiency and increased risk of component detachment during display transfer, resulting in losses.

[0004] Furthermore, with the market expansion of foldable screens, curved screens, irregularly shaped screens, and plastic screens, the performance requirements for bonding materials are becoming increasingly stringent. However, since OCA inevitably suffers some degree of mechanical damage during use, which can lead to the breakage of electronic products, its application is limited to some extent.

[0005] Therefore, developing a silicone resin that can improve the initial tack and mechanical properties of OCA optical adhesive, enable the optical adhesive to have self-healing function, and at the same time ensure low haze, high light transmittance and low yellowing of the optical adhesive is an urgent problem to be solved in this field. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a self-healing silicone resin, its preparation method, and its applications. The self-healing silicone resin is used to prepare OCA optical adhesive. While ensuring the high light transmittance, low yellowing, and good mechanical properties of the OCA optical adhesive, it can improve the initial tack of the OCA optical adhesive and also endow the OCA optical adhesive with self-healing function, thereby improving repair efficiency.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a self-healing silicone resin, wherein the molecular structure of the self-healing silicone resin contains disulfide bonds and thiol groups; the content of disulfide bonds in the self-healing silicone resin is >0.6 mmol / g.

[0009] In this invention, by introducing disulfide bonds and thiol groups into the molecular structure of silicone resin and controlling the content of disulfide bonds within a specific range, OCA optical adhesive can be endowed with self-healing function, resulting in OCA optical adhesive with high self-healing efficiency, which can effectively protect electronic products; it can also improve the initial tack of OCA optical adhesive, avoid component detachment and loss, and improve production efficiency; at the same time, it can also ensure that OCA optical adhesive has low haze, high light transmittance, low yellowing and good mechanical properties.

[0010] In this invention, the content of disulfide bonds in the self-healing silicone resin is >0.6 mmol / g, for example, it can be 0.62 mmol / g, 0.65 mmol / g, 0.68 mmol / g, 0.7 mmol / g, 0.72 mmol / g, 0.75 mmol / g, 0.78 mmol / g, 0.8 mmol / g, 0.82 mmol / g, 0.85 mmol / g, 0.88 mmol / g, 0.9 mmol / g, 0.95 mmol / g, 1 mmol / g, 1.1 mmol / g, 1.2 mmol / g, 1.3 mmol / g, 1.4 mmol / g, 1.5 mmol / g, 1.6 mmol / g, 1.7 mmol / g, 1.8 mmol / g, etc., more preferably 0.8 to 1.8 mmol / g, and even more preferably 1.0 to 1.6 mmol / g.

[0011] Preferably, the number average molecular weight of the self-healing silicone resin is 10,000 to 30,000, for example, it can be 10,000, 12,000, 14,000, 16,000, 18,000, 20,000, 22,000, 25,000, 28,000, etc.

[0012] Preferably, the polydispersity index of the self-healing silicone resin is 1.2 to 1.4, for example, it can be 1.2, 1.22, 1.24, 1.26, 1.28, 1.3, 1.32, 1.34, 1.36, 1.38, etc.

[0013] Preferably, the raw materials for preparing the self-healing silicone resin include mercaptosilane, first alkylsilane, and sulfur-containing silane.

[0014] Preferably, the molar ratio of the mercaptosilane, the first alkylsilane, and the sulfur-containing silane is (0.6–2):(3–15):1; wherein, the specific values ​​of (0.6–2) can be, for example, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 1.95, etc.; and the specific values ​​of (3–15) can be, for example, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 14.5, etc.

[0015] Preferably, the mercaptosilane includes at least one of 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltributoxysilane, mercaptopropyldimethoxymethylsilane, and 3-octanoylthiopropyltriethoxysilane.

[0016] Preferably, the first alkylsilane includes at least one of methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, methylethyldimethoxysilane, methylethyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, methylvinyldimethoxysilane, or methylvinyldiethoxysilane.

[0017] Preferably, the sulfur-containing silane includes bis-[3-(triethoxysilane)-propyl]-disulfide and / or bis-(3-triethoxysilanepropyl)-tetrasulfide.

[0018] In some embodiments, the self-healing silicone resin has the following structure:

[0019]

[0020] In a second aspect, the present invention provides a method for preparing the self-healing silicone resin described in the first aspect, the method comprising the following steps:

[0021] The self-healing silicone resin is obtained by mixing mercaptosilane, first alkylsilane, sulfur-containing silane with water and reacting them.

[0022] Preferably, the water mass is 20-70% of the total mass of mercaptosilane, first alkylsilane and sulfur-containing silane, for example, it can be 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, etc.

[0023] Preferably, the mixture also includes an acid.

[0024] In this invention, the acid includes, but is not limited to, hydrochloric acid.

[0025] Preferably, the mass of the acid is 1 to 5% of the mass of the water, for example, it can be 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, etc.

[0026] In this invention, the mixed materials may further include an organic solvent, which includes at least one of isopropanol, toluene, acetonitrile, 1,4-dioxane, and cyclohexanone.

[0027] Preferably, the reaction temperature is 40–80°C, for example, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, etc.; the reaction time is 1–6 hours, for example, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, etc.

[0028] Preferably, the reaction further includes a post-processing step.

[0029] Preferably, the post-processing includes at least one of extraction, washing, and vacuum distillation.

[0030] In this invention, the solvent for extraction includes, but is not limited to, toluene; the washing includes washing the extract with water until neutral; the temperature of the vacuum distillation is 120-150°C until no distillate is obtained.

[0031] In a second aspect, the present invention provides an optical adhesive, comprising, by weight, 15-60 parts of mercaptosilicone resin, 35-80 parts of silicone-modified polyurethane and 0.5-5 parts of initiator; wherein the mercaptosilicone resin is the self-healing silicone resin described in the first aspect; and the silicone-modified polyurethane is a silicone-modified polyurethane with double bonds capped.

[0032] In this invention, the thiol groups in the thiol silicone resin can undergo a click reaction with the double bonds in the organosilicon-modified polyurethane to form a covalent bond network, providing a framework for the organosilicon OCA. By compounding the thiol silicone resin with the organosilicon-modified polyurethane, the bonding strength of the optical adhesive can be further improved. The dynamic reversibility of the disulfide bond combined with the NH bond can further improve the self-healing effect of the optical adhesive, while ensuring that the optical adhesive has high light transmittance, low haze, low yellowing and good mechanical properties. Moreover, the reaction rate is fast, which can improve production efficiency.

[0033] In this invention, 15 to 60 parts of mercaptosilicone resin can be, for example, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, etc.

[0034] In this invention, 35 to 80 parts of organosilicon-modified polyurethane can be, for example, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, etc.

[0035] In this invention, 0.5 to 5 parts of initiator can be, for example, 0.5 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, etc.

[0036] Preferably, the silicone-modified polyurethane is an acrylic-terminated silicone-modified polyurethane.

[0037] Preferably, the raw materials for preparing the organosilicon-modified polyurethane include hydroxyl-terminated polycarbosilane, polyisocyanate, first polyol and hydroxyl-containing acrylate.

[0038] In this invention, hydroxyl-terminated polysiloxane is used, which, compared to hydroxyl-terminated polysiloxane, is beneficial for further improving the light transmittance of the optical adhesive and reducing its haze.

[0039] Preferably, the molar ratio of the hydroxyl-terminated polycarbosilane, polyisocyanate, and first polyol is 1:(1.8-3.5):(0.5-2); wherein, the specific values ​​of (1.8-3.5) can be, for example, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, etc.; and the specific values ​​of (0.5-2) can be, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, etc.

[0040] Preferably, the molar ratio of the hydroxyl-containing acrylate to the polyisocyanate is (0.2-0.8):1; wherein the specific values ​​of (0.2-0.8) can be, for example, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, etc.

[0041] Preferably, the raw materials for preparing the hydroxyl-terminated polycarbosilane include a second alkylsilane and a second polyol in a molar ratio of 1:(1.1 to 1.5), wherein the specific value of (1.1 to 1.5) can be, for example, 1.1, 1.2, 1.3, 1.4, 1.5, etc.

[0042] In this invention, the hydroxyl-containing acrylates include, but are not limited to, hydroxyethyl acrylate.

[0043] In this invention, the polyisocyanate includes, but is not limited to, at least one of toluene diisocyanate, diphenylmethane diisocyanate, 1,6-hexane diisocyanate, and isophorone diisocyanate.

[0044] The first polyol and the second polyol may be the same or different, and each independently includes, but is not limited to, at least one of ethylene glycol, propylene glycol, hexanediol, 1,4-butanediol, neopentyl glycol, glycerol, polyether triol, and polytetrahydrofuran.

[0045] The second alkylsilane is selected from the same range as the first alkylsilane, and the two may be the same or different.

[0046] In this invention, the method for preparing the hydroxyl-terminated polycarbosilane includes: mixing a second alkylsilane and a second polyol for 20-40 min, reacting at 70-90°C for 2-3 h; then heating to 100-110°C and distilling at atmospheric pressure for 2-3 h; finally heating to 160-170°C and distilling under reduced pressure for 2-3 h until no low-boiling substances precipitate, and then stopping the reaction to obtain the hydroxyl-terminated polycarbosilane.

[0047] In this invention, the preparation method of the organosilicon-modified polyurethane includes: mixing hydroxyl-terminated polycarbosilane, polyisocyanate and a first polyol, heating to 40-60°C, reacting under organotin catalysis for 2-6 hours, then adding hydroxyl-containing acrylate, reacting for 0.5-2 hours, and then heating to 60-80°C and evaporating low-boiling substances under reduced pressure to obtain the organosilicon-modified polyurethane.

[0048] Preferably, the initiator comprises a macromolecular UV initiator.

[0049] In this invention, the macromolecular UV initiator contains C=C, silicon-oxygen bonds, phenyl groups, and carbonyl groups in its molecular structure.

[0050] In some embodiments, the macromolecular UV initiator has the following structure.

[0051]

[0052] Preferably, the raw materials for preparing the initiator include a small molecule initiator, a third alkylsilane, and a third polyol in a molar ratio of 1:(1-3):(1.5-4); wherein, the specific values ​​of (1-3) can be, for example, 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, etc.; and the specific values ​​of (1.5-4) can be, for example, 1.5, 1.6, 1.8, 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5, 3.8, 4, etc.

[0053] In this invention, the third alkylsilane is selected from the same range as the first alkylsilane, and the two may be the same or different; the third polyol is selected from the same range as the first polyol, and the two may be the same or different; more preferably, the third polyol is a diol, including but not limited to at least one of ethylene glycol, propylene glycol, hexanediol, 1,4-butanediol, neopentyl glycol, and polytetrahydrofuran.

[0054] Preferably, the small molecule initiator includes benzophenone initiators.

[0055] In this invention, the small molecule initiator includes, but is not limited to, at least one of DAROCUR 1173, IRGACURE 127, and IRGACURE 2959.

[0056] In this invention, a macromolecular initiator with a specific structure is used, which can improve the drawback of small molecule photoinitiators causing yellowing of materials due to easy migration.

[0057] In this invention, the preparation method of the macromolecular UV initiator includes: mixing a small molecule initiator, a third alkoxysilane, and a third polyol evenly, reacting at 120–160°C for 4–8 h, and then distilling under reduced pressure at 140–180°C for 1–4 h to obtain the macromolecular UV initiator.

[0058] Fourthly, the present invention provides an OCA optical adhesive, the OCA optical adhesive comprising a light release film, an optical adhesive layer and a heavy release film stacked sequentially; the material of the optical adhesive layer comprises the optical adhesive described in the third aspect.

[0059] Fifthly, the present invention provides a display screen comprising the OCA optical adhesive described in the fourth aspect.

[0060] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0061] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0062] The silicone resin provided by this invention, by introducing disulfide bonds and thiol groups into the molecular structure of the silicone resin and controlling the content of disulfide bonds within a specific range, can endow optical adhesives with self-healing function, resulting in optical adhesives with high self-healing efficiency, which can effectively protect electronic products; it can also improve the initial tack of the optical adhesive, avoid component detachment and loss, and improve production efficiency; at the same time, it can also ensure that the optical adhesive has low haze, high light transmittance, low yellowing and good mechanical properties. Detailed Implementation

[0063] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0064] Example 1

[0065] This embodiment provides a self-healing silicone resin, the raw materials of which include 3-mercaptopropyltrimethoxysilane, a first alkylsilane and bis-[3-(triethoxysilane)propyl]-disulfide (Si-75) in a molar ratio of 0.83:4.94:1; the first alkylsilane includes methyltrimethoxysilane and dimethyldimethoxysilane in a molar ratio of 0.187:1.

[0066] This embodiment provides a method for preparing self-healing silicone resin, specifically including the following steps:

[0067] A dry round-bottom flask equipped with a mechanical stirrer, thermometer, and condenser was placed in an oil bath. 170.94 g of Si-75, 58.90 g of 3-mercaptopropyltrimethoxysilane, 38.14 g of methyltrimethoxysilane, and 180.33 g of dimethyldimethoxysilane were added to the flask and stirred at room temperature. Then, a mixed solution of 4.6 g of HCl and 132.89 g of water was added dropwise. After the addition was complete, the temperature was raised to 60°C, and the reaction was allowed to proceed for 3 hours. Next, 200 g of toluene was added to extract the product, and the extract was washed with water until neutral. The apparatus was then changed to a vacuum distillation apparatus, and the temperature was raised to 140°C for vacuum distillation until no distillate was obtained, thus stopping the reaction and yielding the self-healing silicone resin, labeled SSi-1.

[0068] Example 2

[0069] This embodiment provides a self-healing silicone resin, the raw materials of which include 3-mercaptopropyltrimethoxysilane, a first alkylsilane and Si-75 in a molar ratio of 0.93:6.4:1; the first alkylsilane includes methyltrimethoxysilane and dimethyldimethoxysilane in a molar ratio of 0.28:1.

[0070] This embodiment provides a method for preparing a self-healing silicone resin. The difference between this method and Example 1 is that the mass of dimethyldimethoxysilane remains unchanged, and the mass of other raw materials is adjusted to meet the above molar ratio. The mass of HCl is 4.5g, and other parameters are the same as in Example 1. The resulting self-healing silicone resin is labeled as SSi-2.

[0071] Example 3

[0072] This embodiment provides a self-healing silicone resin, the raw materials of which include 3-mercaptopropyltrimethoxysilane, a first alkylsilane and Si-75 in a molar ratio of 1.08:8.58:1; the first alkylsilane includes methyltrimethoxysilane and dimethyldimethoxysilane in a molar ratio of 0.373:1.

[0073] This embodiment provides a method for preparing a self-healing silicone resin. The difference between this method and Example 1 is that the mass of dimethyldimethoxysilane remains unchanged, and the mass of other raw materials is adjusted to meet the above molar ratio. The mass of HCl is 4.3g, and other parameters are the same as in Example 1. The resulting self-healing silicone resin is labeled as SSi-3.

[0074] Example 4

[0075] This embodiment provides a self-healing silicone resin, the raw materials of which include 3-mercaptopropyltrimethoxysilane, a first alkylsilane and Si-75 in a molar ratio of 1.25:10.75:1; the first alkylsilane includes methyltrimethoxysilane and dimethyldimethoxysilane in a molar ratio of 0.433:1.

[0076] This embodiment provides a method for preparing a self-healing silicone resin. The difference between this method and Example 1 is that the mass of dimethyldimethoxysilane remains unchanged, and the mass of other raw materials is adjusted to meet the above molar ratio. The mass of HCl is 4.2g, and other parameters are the same as in Example 1. The resulting self-healing silicone resin is labeled as SSi-4.

[0077] Example 5

[0078] This embodiment provides a self-healing silicone resin, the raw materials of which include 3-mercaptopropyltrimethoxysilane, a first alkylsilane and Si-75 in a molar ratio of 1.5:14:1; the first alkylsilane includes methyltrimethoxysilane and dimethyldimethoxysilane in a molar ratio of 0.493:1.

[0079] This embodiment provides a method for preparing a self-healing silicone resin. The difference between this method and Example 1 is that the mass of dimethyldimethoxysilane remains unchanged, and the mass of other raw materials is adjusted to meet the above molar ratio. The mass of HCl is 4.1g, and other parameters are the same as in Example 1. The resulting self-healing silicone resin is labeled as SSi-5.

[0080] Example 6

[0081] This embodiment provides a self-healing silicone resin, which differs from Example 1 in that Si-75 is replaced with bis-(3-triethoxysilanepropyl)-tetrasulfide with an equal molar content of disulfide bonds, while maintaining the same molar ratio of mercaptosilane, first alkylsilane, and sulfur-containing silane. 3-mercaptopropyltrimethoxysilane is replaced with mercaptopropyldimethoxymethylsilane, and methyltrimethoxysilane and dimethyldimethoxysilane are replaced with ethyltriethoxysilane and diethyldiethoxysilane in a molar ratio of 0.187:1. In the preparation method, the mass of the raw materials can be adjusted according to the molar ratio, and other parameters are the same as in Example 1.

[0082] Example 7

[0083] This embodiment provides a self-healing silicone resin, which differs from Example 1 in that the total molar amount of methyltrimethoxysilane and dimethyldimethoxysilane remains unchanged, and methyltrimethoxysilane is not present. Other preparation materials, amounts, and methods are the same as in Example 1.

[0084] Example 8

[0085] This embodiment provides a self-healing silicone resin, the raw materials of which include 3-mercaptopropyltrimethoxysilane, a first alkylsilane and bis-[3-(triethoxysilane)propyl]-disulfide (Si-75) in a molar ratio of 0.6:15:1; the first alkylsilane includes methyltrimethoxysilane and dimethyldimethoxysilane in a molar ratio of 0.143:1.

[0086] This embodiment provides a method for preparing self-healing silicone resin, specifically including the following steps:

[0087] A dry round-bottom flask equipped with a mechanical stirrer, thermometer, and condenser was placed in an oil bath. 94.96 g of Si-75, 23.56 g of 3-mercaptopropyltrimethoxysilane, 54.49 g of methyltrimethoxysilane, and 312.57 g of dimethyldimethoxysilane were added to the flask and stirred at room temperature. Then, a mixed solution of 4.6 g of HCl and 153.40 g of water was added dropwise. After the addition was complete, the temperature was raised to 60°C, and the reaction was allowed to proceed for 3 hours. Next, 200 g of toluene was added to extract the product, and the extract was washed with water until neutral. The apparatus was then changed to a vacuum distillation apparatus, and the temperature was raised to 140°C for vacuum distillation until no distillate was obtained, thus stopping the reaction and yielding the self-healing silicone resin, labeled SSi-8.

[0088] Example 9

[0089] This embodiment provides a self-healing silicone resin, the raw materials of which include 3-mercaptopropyltrimethoxysilane, a first alkylsilane and bis-[3-(triethoxysilane)propyl]-disulfide (Si-75) in a molar ratio of 1.1:3.2:1; the first alkylsilane includes methyltrimethoxysilane and dimethyldimethoxysilane in a molar ratio of 0.143:1.

[0090] This embodiment provides a method for preparing self-healing silicone resin, specifically including the following steps:

[0091] A dry round-bottom flask equipped with a mechanical stirrer, thermometer, and condenser was placed in an oil bath. 189.93 g of Si-75, 86.39 g of 3-mercaptopropyltrimethoxysilane, 21.80 g of methyltrimethoxysilane, and 134.65 g of dimethyldimethoxysilane were added to the flask and stirred at room temperature. Then, a mixed solution of 4.6 g of HCl and 124 g of water was added dropwise. After the addition was complete, the temperature was raised to 60°C, and the reaction was allowed to proceed for 3 hours. Next, 200 g of toluene was added to extract the product, and the extract was washed with water until neutral. The apparatus was then changed to a vacuum distillation apparatus, and the temperature was raised to 140°C for vacuum distillation until no distillate was obtained, thus stopping the reaction and yielding the self-healing silicone resin, labeled SSi-9.

[0092] Comparative Example 1

[0093] This comparative example provides a self-healing silicone resin, the raw materials of which include 3-mercaptopropyltrimethoxysilane, a first alkylsilane and Si-75 in a molar ratio of 2.2:23.8:1; the first alkylsilane includes methyltrimethoxysilane and dimethyldimethoxysilane in a molar ratio of 0.587:1.

[0094] This comparative example provides a method for preparing a self-healing silicone resin. The difference between this method and Example 1 is that the mass of dimethyldimethoxysilane remains unchanged, and the mass of other raw materials is adjusted to meet the above molar ratio. The mass of HCl is 4.0 g, and other parameters are the same as in Example 1. The obtained self-healing silicone resin is labeled as SSi-1'.

[0095] Comparative Example 2

[0096] This comparative example provides a silicone resin whose raw materials do not include Si-75, and include 3-mercaptopropyltrimethoxysilane and a first alkylsilane in a molar ratio of 1:13; the first alkylsilane includes methyltrimethoxysilane and dimethyldimethoxysilane in a molar ratio of 0.733:1.

[0097] This comparative example provides a method for preparing a self-healing silicone resin. The difference between this method and Example 1 is that the mass of dimethyldimethoxysilane remains unchanged, and the mass of other raw materials is adjusted to meet the above molar ratio. The mass of HCl is 3.7g, and other parameters are the same as in Example 1. The obtained self-healing silicone resin is labeled as SSi-2'.

[0098] Preparation Example 1

[0099] This preparation example provides an acrylate-terminated silicone-modified polyurethane, the preparation method of which includes the following steps:

[0100] (1) A dry round-bottom flask equipped with a mechanical stirrer, thermometer, and condenser was placed in an oil bath. 120.22 g of dimethyldimethoxysilane and 122.90 g of neopentyl glycol were added to the round-bottom flask and stirred at room temperature for 20 min. Then the temperature was raised to 80 °C and reacted for 2 h. The apparatus was changed to an atmospheric distillation apparatus, the temperature was raised to 100 °C and reacted for 2 h. Subsequently, the temperature was gradually raised to 160 °C and reacted for 2 h. The mixture was then distilled under reduced pressure until no low-boiling substances were distilled off, yielding hydroxyl-terminated polycarbosilane, labeled HPSi. The number average molecular weight of HPSi was 1125 g / mol.

[0101] (2) Place the dry round-bottom flask equipped with a mechanical stirrer, thermometer and condenser in an oil bath. Add 650g of HPSi obtained in step (1), 338g of isophorone diisocyanate, 46.96g of trimethylolpropane and 1g of dibutyltin dilaurate into the round-bottom flask and stir at room temperature for 10min. Raise the temperature to 60℃ and react for 3h. Then add 82.45g of hydroxyethyl acrylate and continue to react for 1h. Remove the low-boiling substances under reduced pressure to obtain acrylate-terminated organosilicon modified polyurethane, labeled as PUHPSi-1.

[0102] Preparation Example 2

[0103] This preparation example provides an acrylate-terminated silicone-modified polyurethane, which differs from Preparation Example 1 in that the hydroxyl-terminated polycarbosilane is replaced with an equimolar amount of hydroxyl-terminated polysiloxane; the preparation method includes the following steps:

[0104] A dry round-bottom flask equipped with a mechanical stirrer, thermometer, and condenser was placed in an oil bath. 1040g of hydroxyl-terminated polysiloxane (0.65mol, GY6001, molecular weight 1600, purchased from Shaanxi Siyou Yunji New Materials Co., Ltd.), 338g of isophorone diisocyanate (1.52mol), 46.96g of trimethylolpropane (0.35mol), and 1.4g of dibutyltin dilaurate were added to the round-bottom flask and stirred at room temperature for 10min. The temperature was raised to 60℃ and reacted for 3h. 82.45g of hydroxyethyl acrylate (0.71mol) was added, and the reaction was continued for 1h. Low-boiling substances were removed under reduced pressure to obtain acrylate-terminated organosilicon modified polyurethane, labeled as PUHPSi-1'.

[0105] Preparation Example 3

[0106] This preparation example provides a macromolecular UV initiator, the preparation method of which includes the following steps:

[0107] A dry round-bottom flask equipped with a mechanical stirrer, thermometer, and condenser was placed in an oil bath. 296.46 g of vinyltrimethoxysilane (M = 148.232, n = 2 mol) and 260.38 g of neopentyl glycol (M = 104.15, n = 2.5 mol) were added to the round-bottom flask and stirred at room temperature for 10 min. The temperature was raised to 90 °C and reacted for 2 h, then raised to 120 °C and reacted for 2 h. 164.2 g of 2-hydroxy-2-methylphenylacetone (1 mol) was added, and the temperature was gradually raised to 160 °C and reacted for 1 h. Low-boiling substances were removed under reduced pressure to obtain the macromolecular UV initiator.

[0108] Application Example 1

[0109] This application example provides an optical adhesive comprising, by weight, 32 parts of mercaptosilicone resin (SSi-1 provided in Example 1), 65 parts of acrylate-terminated organosilicon-modified polyurethane (PUHPSi-1 provided in Preparation Example 1) and 3 parts of macromolecular initiator (provided in Preparation Example 3).

[0110] The preparation method of the optical adhesive includes: mixing mercapto silicone resin, acrylate-terminated organosilicon modified polyurethane and macromolecular initiator, stirring evenly, and vacuum degassing to obtain the optical adhesive.

[0111] Application Examples 2-5

[0112] Application Examples 2-5 provide an optical adhesive, which differs from Application Example 1 in that the mercapto silicone resin used is the self-healing silicone resin provided in Examples 2-5, while the other components, dosages, and preparation methods are the same as in Application Example 1.

[0113] Application Examples 6-7

[0114] Application Examples 6 and 7 provide optical adhesives, which differ from Application Example 1 in that the mercapto silicone resins used are the self-healing silicone resins provided in Examples 6 and 7, and the ratio of vinyl groups to mercapto groups, other components, and preparation methods are the same as in Application Example 1.

[0115] Application Example 8

[0116] This application example provides an optical adhesive, which, by weight, comprises 56 parts of mercaptosilicone resin (SSi-8 provided in Example 8), 41 parts of acrylate-terminated organosilicon-modified polyurethane (PUHPSi-1 provided in Preparation Example 1), and 3 parts of macromolecular initiator (provided in Preparation Example 3). The preparation method of the optical adhesive is the same as that of Application Example 1.

[0117] Application Example 9

[0118] This application example provides an optical adhesive, which, by weight, comprises 24 parts of mercaptosilicone resin (SSi-9 provided in Example 9), 73 parts of acrylate-terminated organosilicon-modified polyurethane (PUHPSi-1 provided in Preparation Example 1), and 3 parts of macromolecular initiator (provided in Preparation Example 3). The preparation method of the optical adhesive is the same as that of Application Example 1.

[0119] Compare and contrast examples 1 and 2

[0120] Comparative Application Examples 1 and 2 provide optical adhesives, which differ from Application Example 1 in that the mercaptosilicone resin used is the same as that provided in Comparative Examples 1 and 2, while the other components, amounts and preparation methods are the same as those in Application Example 1.

[0121] Comparative Application Example 3

[0122] Comparative Application Example 3 provides an optical adhesive that differs from Application Example 2 in that the acrylate-terminated silicone-modified polyurethane is PUHPSi-1' provided in Preparation Example 2, while the other components, amounts, and preparation methods are the same as in Application Example 2.

[0123] Performance testing

[0124] The test results for disulfide bond content, number-average molecular weight, polydispersity index, transmittance, and haze in the silicone resins provided in the test examples and comparative examples are shown in Table 1.

[0125] The disulfide bond content was tested according to the Ellman method.

[0126] Number-average molecular weight and polydispersity index: tested according to GB / T 21864-2008.

[0127] Transmittance and haze tests: The tests shall be conducted in accordance with GB / T 2410 7.1.

[0128] Table 1

[0129]

[0130] The optical adhesives provided in the application examples and comparative application examples were coated onto a first release film using a selected blade coating method to achieve a thickness of 250 μm (using a THVG-1100 coating machine from Shangwang Printing Machinery Co., Ltd.). A second release film was then attached to the side of the optical adhesive away from the first release film, followed by UV curing (curing conditions: 365 nm, 5 min) to obtain the OCA optical adhesive. Performance tests were performed on peel strength, light transmittance, haze, yellowing, elongation at break, and self-healing properties.

[0131] (1) Light transmittance and haze test: The test shall be conducted in accordance with GB / T 2410 7.1.

[0132] (2) Yellowing: Tested in accordance with GB / T 39294-2020.

[0133] (3) Peel strength: Remove the release film from the OCA optical adhesive and adhere it to the substrate surface. Then, adhere the PET film to the side of the OCA optical adhesive away from the substrate to form a PET-organic silicone OCA-substrate composite structure. Place it on an electric roller machine (Beidou Instruments PT-509) and use a 3kg roller to cyclically roll it once at a speed of 10mm / s to obtain the peel strength test sample of the corresponding substrate. Test the 180° peel strength according to GB / T2792-2014.

[0134] (4) Elongation at break test: The test shall be conducted in accordance with GB / T 528-2009.

[0135] (5) Self-healing performance: The recovery rate of the sample after fracture was tested. The fractured sample was placed at room temperature for 4 hours and tested in accordance with GB / T 528-2009.

[0136] The specific test results are shown in Table 2.

[0137] Table 2

[0138]

[0139] As shown in Table 2, the self-healing silicone resin provided by this invention, by introducing disulfide bonds and thiol groups into the molecular structure of the silicone resin and controlling the content of disulfide bonds within a specific range, can endow OCA optical adhesive with self-healing function, resulting in OCA optical adhesive with high self-healing efficiency, which can effectively protect electronic products; it can also improve the initial tack of the optical adhesive, avoid component detachment and loss, and improve production efficiency; at the same time, it can also ensure that the optical adhesive has low haze, high light transmittance, low yellowing and good mechanical properties; the fracture recovery rate of OCA optical adhesive including the self-healing resin is ≥36%, and can even reach 85-87%; the peel force is ≥12.169N / 25mm.

[0140] As shown in Application Examples 1-5 and Comparative Application Example 1-2, when the molar content of disulfide bonds is between 0.87 and 1.4 mmol / g, the self-repairing effect improves with increasing disulfide bond content. However, when the disulfide bond content continues to increase beyond 1.4 mmol / g, the improvement in self-repairing performance is not significant. When the disulfide bond content is below 0.6 mmol / g, the self-repairing performance is not significantly different from that without disulfide bonds.

[0141] As can be seen from Application Example 2 and Comparative Application Example 3, modifying polyurethane with hydroxyl-terminated polysiloxanes results in optical adhesives with higher haze and lower light transmittance.

[0142] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An optical adhesive, characterized in that, The optical adhesive comprises 15-60 parts by weight of mercaptosilicone resin, 35-80 parts by weight of silicone-modified polyurethane, and 0.5-5 parts by weight of initiator; The mercaptosilicone resin is a self-healing silicone resin; The self-healing silicone resin contains disulfide bonds and thiol groups in its molecular structure; The self-healing silicone resin contains 0.8~1.4 mmol / g of disulfide bonds; The self-healing silicone resin is prepared by the following method, which includes the following steps: mixing mercaptosilane, first alkylsilane, sulfur-containing silane with water, reacting, and obtaining the self-healing silicone resin; The silicone-modified polyurethane is an acrylate-terminated silicone-modified polyurethane. The raw materials for preparing the organosilicon-modified polyurethane include hydroxyl-terminated polycarbosilane, polyisocyanate, first polyol and hydroxyl-containing acrylate.

2. The optical adhesive according to claim 1, characterized in that, The number-average molecular weight of the self-healing silicone resin is 10,000 to 30,000.

3. The optical adhesive according to claim 1, characterized in that, The polydispersity index of the self-healing silicone resin is 1.2~1.

4.

4. The optical adhesive according to claim 1, characterized in that, The molar ratio of the mercaptosilane, the first alkylsilane, and the sulfur-containing silane is (0.6~2):(3~15):

1.

5. The optical adhesive according to claim 1, characterized in that, The mercaptosilane includes at least one of 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltributoxysilane, mercaptopropyldimethoxymethylsilane, and 3-octanoylthiopropyltriethoxysilane.

6. The optical adhesive according to claim 1, characterized in that, The first alkylsilane includes at least one of methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, methylethyldimethoxysilane, methylethyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, methylvinyldimethoxysilane, or methylvinyldiethoxysilane.

7. The optical adhesive according to claim 1, characterized in that, The sulfur-containing silanes include bis-[3-(triethoxysilane)-propyl]-disulfide and / or bis-[3-(triethoxysilane)-propyl]-tetrasulfide.

8. The optical adhesive according to claim 1, characterized in that, The mass of the water is 20-70% of the total mass of mercaptosilane, first alkylsilane and sulfur-containing silane.

9. The optical adhesive according to claim 1, characterized in that, The mixture also includes acid.

10. The optical adhesive according to claim 9, characterized in that, The mass of the acid is 1 to 5% of the mass of the water.

11. The optical adhesive according to claim 1, characterized in that, The reaction is carried out at a temperature of 40-80°C for 1-6 hours.

12. The optical adhesive according to claim 1, characterized in that, The reaction also includes a post-processing step.

13. The optical adhesive according to claim 12, characterized in that, The post-processing includes at least one of extraction, washing, and vacuum distillation.

14. The optical adhesive according to claim 1, characterized in that, The molar ratio of the hydroxyl-terminated polycarbosilane, polyisocyanate, and first polyol is 1:(1.8~3.5):(0.5~2).

15. The optical adhesive according to claim 1, characterized in that, The molar ratio of the hydroxyl-containing acrylate to the polyisocyanate is (0.2~0.8):

1.

16. The optical adhesive according to claim 1, characterized in that, The raw materials for preparing the hydroxyl-terminated polycarbosilane include a second alkylsilane and a second polyol in a molar ratio of 1:(1.1~1.5).

17. The optical adhesive according to claim 1, characterized in that, The initiator includes a macromolecular UV initiator.

18. The optical adhesive according to claim 1, characterized in that, The raw materials for preparing the initiator include a small molecule initiator, a third alkylsilane, and a third polyol in a molar ratio of 1:(1~3):(1.5~4).

19. The optical adhesive according to claim 18, characterized in that, The small molecule initiators include benzophenone initiators.

20. An OCA optical adhesive, characterized in that, The OCA optical adhesive comprises a light release film, an optical adhesive layer, and a heavy release film stacked sequentially; the material of the optical adhesive layer comprises the optical adhesive according to any one of claims 1 to 19.

21. A display screen, characterized in that, The display screen includes the OCA optical adhesive as described in claim 20.

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