High-weather-resistance self-repairing optical adhesive and preparation method thereof

Abstract

The invention relates to the technical field of adhesives, in particular to a high-weather-resistance self-repairing optical adhesive and a preparation method thereof. The fluorine-containing silicone rubber composition comprises 85-95 parts of a fluorine-containing silicone prepolymer; 2-5 parts of a photoinitiator solution; 3-10 parts of a silane coupling agent; the fluorine-containing siloxane prepolymer, the benzene boric acid ester monomer, the multifunctional acrylate, the photoinitiator and the silane coupling agent are compounded, so that the prepared high-weather-resistance self-repairing optical adhesive simultaneously realizes ultralow water and oxygen permeation, self-repairing under mild conditions and yellowing resistance, and meets the outdoor durability requirement of a display screen.

Description

Technical Field

[0001] The present invention relates to the technical field of adhesives, and in particular to a highly weather-resistant self-repairing optical adhesive and a preparation method thereof. Background Art

[0002] With the development of society, display screen devices are currently widely used in various industries, such as automobiles, industrial control, medical treatment, military, ships, aviation, etc. Various components require adhesives, which are required to be colorless and transparent, have good light transmittance, good adhesive strength, and be resistant to extreme environments such as high temperature and high humidity.

[0003] In real-world use, display screens must withstand the combined effects of weathering, such as light, temperature, dryness, and high humidity. This ability to withstand these conditions is known as weather resistance, and the adhesives used to form these films must also possess excellent weather resistance. For example, Chinese patent publication number CN1227320C discloses a weather-resistant epoxy conductive adhesive composed of a mixture of E-51 epoxy resin, 650 low-molecular-weight polyamide, a light stabilizer, a UV absorber, an antioxidant, and silver powder. This invention incorporates antioxidants, light stabilizers, and UV absorbers into the conventional epoxy conductive adhesive formula, effectively enhancing the adhesive's antioxidant, light, and UV resistance.

[0004] However, including the above-mentioned adhesives, ordinary adhesives are very easy to hydrolyze and oxidize under hot and humid conditions, resulting in bubbles and even microcracks between the substrate films.

[0005] In order to solve the above problems, the present invention provides a highly weather-resistant self-repairing optical adhesive and a preparation method thereof. Summary of the Invention

[0006] The object of the present invention is to provide a highly weather-resistant self-repairing optical adhesive and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0008] A highly weather-resistant self-repairing optical adhesive, comprising the following substances in parts by weight:

[0009] 85-95 parts of fluorinated silicone prepolymer

[0010] 2-5 parts of photoinitiator solution

[0011] 3-10 parts of silane coupling agent;

[0012] Among them, the fluorinated silicone prepolymer is prepared by reacting hydrogenated silicone oil, fluorinated vinyl monomer, multifunctional acrylate, and benzene borate monomer under the action of a catalyst.

[0013] More optimally, the raw materials for preparing the fluorinated silicone prepolymer include: 50-65 parts of hydrogenated silicone oil, 25-35 parts of fluorinated vinyl monomer, 45-55 parts of multifunctional acrylate, 60-75 parts of benzene borate monomer, 10-20 parts of solvent, and 10-50 parts of catalyst.

[0014] More optimally, the solid content of the photoinitiator solution is 30-45%, the photoinitiator is at least one of TPO, 184, and 1173; and the silane coupling agent is at least one of KH550 and KH560.

[0015] More optimally, the hydrogen-containing silicone oil is at least one of Dow Corning's MHX-110730cs / 20cs, Japan's Shin-Etsu KF-99, and Maitu TSF484.

[0016] More preferably, the fluorine-containing vinyl monomer is at least one of tetrafluoroethylene (TFE), chlorotrifluoroethylene (CTFE), and hexafluoropropylene (HFP).

[0017] More optimally, the multifunctional acrylate is at least one of tripropylene glycol acrylate (TPGDA) and hexanediol diacrylate (HDDA); the benzene borate monomer is at least one of catechol borate (B2Cat2) and 3-acrylamidophenylboronic acid (3-AAPBA).

[0018] More optimally, the solvent is at least one of toluene and xylene (an aprotic solvent to prevent hydrolysis of siloxane chains); and the catalyst is a Karstedt catalyst.

[0019] More optimally, highly weather-resistant self-repairing optical adhesives are used for bonding optical components in display devices.

[0020] The present invention also provides a method for preparing a highly weather-resistant self-repairing optical adhesive, comprising the following steps:

[0021] Step 1: Preparation of fluorosilicone prepolymer

[0022] Weigh the raw materials according to the formula, add hydrogenated silicone oil and fluorinated vinyl monomer into the reactor, heat to 75-120°C under nitrogen protection, start adding the catalyst dropwise, react for 4-6 hours, take samples for infrared testing, and wait until the Si-H peak (2140cm -1 ) disappears; then the temperature is lowered to 55-80°C, multifunctional acrylate and benzene borate monomer are added in sequence, and the reaction is continued for 3-6 hours and then the temperature is lowered to obtain a fluorinated silicone prepolymer;

[0023] Step 2: Preparation of highly weather-resistant self-healing optical adhesive.

[0024] The raw materials were weighed according to the formula, and the above-mentioned fluorinated silicone prepolymer, silane coupling agent, and photoinitiator were placed in a container and stirred for 30 minutes to obtain a highly weather-resistant self-repairing optical adhesive.

[0025] More optimally, when preparing the fluorinated silicone prepolymer, the temperature is first raised to 80±1°C and reacted for 6 hours; then the temperature is lowered to 60±1°C and reacted for 4 hours.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) In the present invention, the introduction of fluorine-containing side chains into the siloxane segment (-Si-O-Si-) can reduce the surface energy (contact angle > 110°), block water and oxygen penetration, and improve the moisture resistance of the adhesive.

[0028] (2) In the present invention, a benzene borate group is embedded in the siloxane monomer to achieve self-repairing under wet and hot conditions (repair rate >75% under 60°C / 85% RH conditions) while suppressing oxidative yellowing caused by hydroxyl groups.

[0029] (3) In the present invention, UV-induced free radical polymerization—acrylate groups rapidly solidify to form a primary network, heat-activated silanol condensation—siloxane end groups dehydrate to form a Si-O-Si three-dimensional skeleton, dynamic bond reconstruction—boric acid ester bonds reversibly interact with water molecules in the environment, and continuously repair interface defects, thereby improving the weather resistance of the adhesive in a three-stage crosslinking manner. DETAILED DESCRIPTION

[0030] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0031] The present invention prepares a variety of highly weather-resistant self-repairing optical adhesives through several examples and comparative examples, and verifies their performance. The raw materials used in the examples are shown in Table 1.

[0032] Table 1 Raw materials used in various embodiments and comparative examples of the present invention

[0033]

[0034]

[0035] The highly weather-resistant self-repairing optical adhesives prepared in Examples 1-4 and Comparative Examples 1-5 of the present invention were prepared according to the following steps:

[0036] Step 1: Preparation of fluorosilicone prepolymer

[0037] Weigh the raw materials according to the formula, add hydrogenated silicone oil and fluorinated vinyl monomer into the reactor, heat to 80°C under nitrogen protection, start adding the catalyst dropwise, react for 6 hours, take samples for infrared testing, and wait until the Si-H peak (2140cm -1 ) disappears; then the temperature is lowered to 60°C, multifunctional acrylate and benzene borate monomer are added in sequence, and the reaction is continued for 4 hours and then the temperature is lowered to obtain a fluorinated silicone prepolymer.

[0038] Specifically, in this example, the hydrogen-containing silicone oil selected was Dow Corning's MHX-110730cs / 20cs and Japan Shin-Etsu KF-99, the fluorine-containing vinyl monomer selected was tetrafluoroethylene and chlorotrifluoroethylene, the multifunctional acrylate selected was tripropylene glycol acrylate and ethylene glycol diacrylate, the benzene borate monomer selected was terephthalate borate and 3-acrylamidophenylboric acid, the catalyst selected was Karstedt catalyst, and the solvent selected was toluene.

[0039] The formula (feed ratio) of the fluorinated silicone prepolymer is shown in Table 2.

[0040] Step 2: Preparation of highly weather-resistant self-healing optical adhesive

[0041] The raw materials were weighed according to the formula, the photoinitiator was dissolved in toluene, and the mixture was thoroughly mixed to obtain a photoinitiator solution; the above-mentioned fluorinated silicone prepolymer, silane coupling agent, and photoinitiator were placed in a container and stirred for 30 minutes to obtain a highly weather-resistant self-repairing optical adhesive.

[0042] Specifically, in this example, KH550 and KH560 were used as silane coupling agents, and TPO and 184 were used as photoinitiators. The formula (ingredient ratio) of the highly weather-resistant self-healing optical adhesive is shown in Table 2.

[0043] Table 2 Formulations of Examples and Comparative Examples

[0044]

[0045]

[0046] The specific production methods are:

[0047] A highly weather-resistant, self-healing optical adhesive was applied to the corona surface of a flexible substrate layer (50μm PET) using a comma blade coater. UV light (365nm wavelength, 800mJ / cm²) was irradiated onto the surface of the UV-reducing tape for 5 seconds. The tape was then placed in a 120°C oven for 30 minutes to evaporate the solvent and form an adhesive layer with a thickness of 25±2μm. The dried adhesive layer was then laminated to the release surface of a release film (Yaoyang New Materials, 50μm thickness, release force of 15-20g / inch). The coated UV-reducing tape was then aged at 23°C / 50% RH for 24 hours to produce a highly weather-resistant, self-healing optical tape. After aging, the tape was placed at room temperature for 2 hours before performance testing.

[0048] The specific test methods are as follows:

[0049] 1. Adhesive layer thickness test

[0050] The thickness of the adhesive layer of the highly weather-resistant, self-healing optical tape is the difference in thickness before and after removal of the adhesive layer on a specific surface of the sample, measured at room temperature (23°C). The arithmetic average of the thickness differences before and after removal of the adhesive layer at three different locations on the sample is taken as the thickness of the adhesive layer on the measured surface. The specific adhesive layer removal process for the sample surface is as follows: the adhesive layer on a specific surface of the sample is swelled with ethyl acetate and then wiped off with a dust-free cloth. The sample after the adhesive layer is wiped off is then dried in a 60°C oven for 30 minutes before the thickness test is performed.

[0051] 2. Contact angle test

[0052] The water drop contact angle of the adhesive layer of the highly weather-resistant self-repairing optical tape is the contact angle of the sample measured at room temperature of 23° C. using deionized water as the standard test solution, and the arithmetic average of the contact angles of samples at 5 different positions is taken as the contact angle of the measured sample.

[0053] 3. Self-repair test observation

[0054] The samples were treated at 60°C / 85% RH for 2 h and then the crack widths of the samples before and after aging were observed using a laser confocal microscope at room temperature (23°C).

[0055] 4. Yellowing index test

[0056] The ΔYI values ​​were measured using a colorimeter under D65 illuminant. The final results are shown in Table 3.

[0057] Table 3 Performance test results of optical adhesives prepared in different embodiments and comparative examples

[0058]

[0059]

[0060] As can be seen from Table 3, the present invention configures a certain proportion of fluorinated silicone prepolymer, photoinitiator, and silane coupling agent, and when ultraviolet light (365nm wavelength, energy 800mJ / cm 2 ) is irradiated on the surface of the highly weather-resistant self-healing optical adhesive for 5s. UV triggers the rapid solidification of the acrylate groups to form a primary network, the siloxane end groups are dehydrated at high temperature to form a Si-O-Si three-dimensional skeleton, and the borate bonds reversibly interact with water molecules in the environment and continuously repair interface defects to achieve the effect of highly weather-resistant self-healing.

[0061] It can be seen from Examples 1, 2, 3, and 4 that the water contact angle of the highly weather-resistant self-repairing optical adhesive is ≥112°, the self-repair rate for cracks of about 50 μm is ≥75%, and the yellowing index ΔYI is ≤2.0.

[0062] From the comparison between Example 1 and Comparative Examples 1, 2 and 3, it can be seen that the raw materials of the fluorinated silicone prepolymer do not contain fluorinated vinyl monomers or are not within the scope of the technical solution of the present invention, which will result in the high weather-resistant self-repairing optical adhesive obtained in the polymer having no, insufficient or excessive fluorinated side chains, which will lead to insufficient hydrophobicity, manifested as too low a contact angle.

[0063] From the comparison between Example 1 and Comparative Examples 4, 5 and 6, it can be seen that the raw materials of the fluorinated silicone prepolymer do not contain benzene borate monomers or are not within the scope of the technical solution of the present invention, which will result in the polymer having no, insufficient or excessive BO bonds in the highly weather-resistant self-repairing optical adhesive. When there are no or insufficient BO bonds, the self-repairing ability is absent or insufficient, and the yellowing index ΔYI ≥ 2.0. When there are too many BO bonds, ΔYI ≥ 2.0 is also the same.

[0064] The above descriptions are merely optional embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by utilizing the contents of the present invention specification under the inventive concept of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A highly weather-resistant self-repairing optical adhesive, characterized in that: Calculated by weight, including the following substances: 85-95 parts of fluorinated silicone prepolymer 2-5 parts of photoinitiator solution 3-10 parts of silane coupling agent; The fluorine-containing silicone prepolymer is prepared by reacting hydrogen-containing silicone oil, fluorine-containing vinyl monomer, multifunctional acrylate, and benzene borate monomer under the action of a catalyst.

2. The highly weather-resistant self-repairing optical adhesive according to claim 1, characterized in that: The raw materials for preparing the fluorine-containing silicone prepolymer include: 50-65 parts of hydrogenated silicone oil, 25-35 parts of fluorine-containing vinyl monomer, 45-55 parts of multifunctional acrylate, 60-75 parts of benzene borate monomer, 10-20 parts of solvent, and 10-50 parts of catalyst.

3. The highly weather-resistant self-repairing optical adhesive according to claim 1, characterized in that: The solid content of the photoinitiator solution is 30-45%, and the photoinitiator is at least one of TPO, 184, and 1173; and the silane coupling agent is at least one of KH550 and KH560.

4. The highly weather-resistant self-repairing optical adhesive according to claim 2, characterized in that: The hydrogen-containing silicone oil is at least one of Dow Corning's MHX-110730cs / 20cs, Japan's Shin-Etsu KF-99, and Maitu TSF484.

5. The highly weather-resistant self-repairing optical adhesive according to claim 2, characterized in that: The fluorine-containing vinyl monomer is at least one of tetrafluoroethylene (TFE), chlorotrifluoroethylene (CTFE), and hexafluoropropylene (HFP).

6. The highly weather-resistant self-repairing optical adhesive according to claim 2, characterized in that: The multifunctional acrylate is at least one of tripropylene glycol acrylate (TPGDA) and hexanediol diacrylate (HDDA); the benzene borate monomer is at least one of catechol borate (B2Cat2) and 3-acrylamidophenylboronic acid (3-AAPBA).

7. The highly weather-resistant self-repairing optical adhesive according to claim 2, characterized in that: The solvent is at least one of toluene and xylene (an aprotic solvent to prevent hydrolysis of the siloxane chain); The catalyst is a Karstedt catalyst.

8. The highly weather-resistant self-repairing optical adhesive according to claim 1, characterized in that: The highly weather-resistant self-repairing optical adhesive is used for bonding optical elements in display devices.

9. A method for preparing a highly weather-resistant self-repairing optical adhesive, characterized in that: The steps include: Step 1: Preparation of fluorosilicone prepolymer Weigh the raw materials according to the formula, add hydrogenated silicone oil and fluorinated vinyl monomer into the reactor, heat to 75-120°C under nitrogen protection, start adding the catalyst dropwise, react for 4-6 hours, take samples for infrared testing, and wait until the Si-H peak (2140cm -1 ) disappears; then the temperature is lowered to 55-80°C, multifunctional acrylate and benzene borate monomer are added in sequence, and the reaction is continued for 3-6 hours and then the temperature is lowered to obtain a fluorinated silicone prepolymer; Step 2: Preparation of highly weather-resistant self-healing optical adhesive The raw materials were weighed according to the formula, and the above-mentioned fluorinated silicone prepolymer, silane coupling agent, and photoinitiator were placed in a container and stirred for 30 minutes to obtain a highly weather-resistant self-repairing optical adhesive.

10. The method for preparing a highly weather-resistant self-repairing optical adhesive according to claim 9, characterized in that: When preparing the fluorine-containing silicone prepolymer, the temperature is first raised to 80±1° C. and reacted for 6 hours; then the temperature is lowered to 60±1° C. and reacted for 4 hours.

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