A uv-curable silicone adhesive and a method for preparing the same

Abstract

The present application relates to a kind of UV cured silicone adhesives and its preparation method, by following weight parts of raw materials composition: acrylic modified silicone resin A 60-80 parts, acrylic modified silicone resin B 20-40 parts, free radical initiator 0.1-0.3 parts, adhesion promoter 0.01-0.06 parts;UV cured silicone adhesive prepared by the present application, different from the heating curing mode of traditional silicone, can UV fast curing, while still maintaining the bonding performance of traditional UV glue, improve the UV glue not resistant to cold and hot impact and high temperature and high humidity performance, can be well replaced the application scene needing UV glue.

Description

Technical Field

[0001] This invention relates to UV-curable encapsulation materials, specifically to a UV-curable silicone adhesive and its preparation method. Background Technology

[0002] UV-curable encapsulation materials are widely used in the encapsulation of optical materials because their excellent mechanical, electrical, adhesive, and airtight properties can effectively prevent the silver plating layer from turning black. However, traditional epoxy resins are slightly lacking in weather resistance (UV resistance) and are prone to yellowing during use, which affects their service life. Summary of the Invention

[0003] A UV-curable silicone adhesive and its preparation method are characterized in that it is composed of the following raw materials in parts by weight: 60-80 parts of acrylic modified silicone resin A, 20-40 parts of acrylic modified silicone resin B, 0.1-0.3 parts of free radical initiator, and 0.01-0.06 parts of adhesion promoter.

[0004] The structure of the acrylic-modified silicone resin A is as follows:

[0005] Where n = 500 - 1000.

[0006] The preparation method of the acrylic-modified silicone resin A is as follows:

[0007] Reaction mechanism:

[0008]

[0009] Step 1: Add 1 mol of 2-[(prop-2-enyloxy)methyl]oxetine to a three-necked flask, add chloroplatinic acid as a catalyst (0.01%-0.05% by weight of the entire reaction system), add cyclohexane of equal mass to 2-[(prop-2-enyloxy)methyl]oxetine, stir until homogeneous, heat to 50°C, add 0.5 mol of end-hydrogen-containing silicone oil dropwise, after which heat to 80-100°C and reflux for 3-5 hours, stop the reaction, and then remove the solvent and 2-[(prop-2-enyloxy)methyl]oxetine by vacuum distillation to obtain intermediate 1;

[0010] Step 2: Add intermediate 1 and 1.2 mol of acrylic acid to a three-necked flask, add 1%-5% of the total reaction system weight of the catalyst triphenylphosphine, heat to 120℃, react for 5 h, and then react under vacuum for 3 h to obtain acrylic acid modified organosilicon resin A.

[0011] The structure of the acrylic-modified silicone resin B is as follows:

[0012]

[0013] The preparation method of the acrylic-modified silicone resin B is as follows:

[0014] Reaction mechanism:

[0015]

[0016]

[0017] Step 1: Add 1 mol of 2-[(prop-2-enyloxy)methyl]oxetine to a three-necked flask, add chloroplatinic acid as a catalyst (0.01%-0.03% by weight of the entire reaction system), add cyclohexane of equal mass to 2-[(prop-2-enyloxy)methyl]oxetine, stir until homogeneous, and heat to 50℃-80℃. Add 0.2 mol of tetramethylcyclotetrasiloxane dropwise. After the addition is complete, heat to 80-100℃ and reflux for 3-6 hours. Stop the reaction and remove the solvent and 2-[(prop-2-enyloxy)methyl]oxetine by vacuum distillation to obtain intermediate 2.

[0018] Step 2: Add intermediate 2 and 1.2-1.4 mol of propionic acid to a three-necked flask, add 1%-5% of the total reaction system weight of the catalyst triphenylphosphine, heat to 90-120℃, react for 3-5 hours, and then react under vacuum for 3-5 hours to obtain acrylic acid modified organosilicon resin B.

[0019] The beneficial effects of this invention are: 1. Using an organosilicon structure as the main chain segment of the resin can fully utilize the resistance of organosilicon to damp heat and thermal shock; 2. In the preparation process of the acrylic-modified organosilicon resins A and B, the reaction of acrylic acid ring-opening epoxy is used to introduce a double bond of acrylic acid to provide a curing functional group, and a hydroxyl group is added. The presence of the hydroxyl group can produce physical or chemical reactions with the hydroxyl groups on the surface of the substrate being bonded, which can greatly increase the adhesive performance; 3. Acrylic-modified organosilicon resin B, as a tetrafunctional crosslinking agent, can effectively improve the strength of the adhesive, thereby improving the performance of the adhesive. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions of the present invention, and to make the above-mentioned objectives, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to embodiments.

[0021] First, we will introduce the synthesis methods of two resins; the following examples will not be described in detail.

[0022] The preparation process of acrylic-modified silicone resin A is as follows:

[0023] Step 1: Add 1 mol of 2-[(prop-2-enyloxy)methyl]oxetine to a three-necked flask, add chloroplatinic acid as a catalyst (0.03% by weight of the entire reaction system), and add cyclohexane of equal mass to 2-[(prop-2-enyloxy)methyl]oxetine. Stir until homogeneous and heat to 50°C. Add 0.5 mol of hydrogen-terminated silicone oil dropwise. After the addition is complete, heat to 100°C and reflux for 5 hours. Stop the reaction and remove the solvent and 2-[(prop-2-enyloxy)methyl]oxetine by vacuum distillation to obtain intermediate 1.

[0024] Step 2: Add intermediate 1 and 1.2 mol of acrylic acid to a three-necked flask, add 5% of the total reaction system weight of the catalyst triphenylphosphine, heat to 120°C, react for 5 h, and then react under vacuum for 3 h to obtain acrylic acid modified organosilicon resin A.

[0025] The preparation process of acrylic-modified silicone resin B is as follows:

[0026] Step 1: Add 1 mol of 2-[(prop-2-enyloxy)methyl]oxetine to a three-necked flask, add chloroplatinic acid as a catalyst (0.03% by weight of the entire reaction system), and add cyclohexane of equal mass to 2-[(prop-2-enyloxy)methyl]oxetine. Stir until homogeneous and heat to 80°C. Add 0.2 mol of tetramethylcyclotetrasiloxane dropwise. After the addition is complete, heat to 100°C and reflux. After 5 hours, stop the reaction and remove the solvent and 2-[(prop-2-enyloxy)methyl]oxetine by vacuum distillation to obtain intermediate 2.

[0027] Step 2: Add intermediate 2 and 1.3 mol of propionic acid to a three-necked flask, add 5% of the total reaction system weight of the catalyst triphenylphosphine, heat to 120°C, react for 4 h, and then react under vacuum for 5 h to obtain acrylic acid modified organosilicon resin B.

[0028] Example 1

[0029] Weigh out 60 parts of acrylic modified silicone resin A, where n = 500 in structural formula 1; 20 parts of acrylic modified silicone resin B, 0.1 parts of free radical initiator, and 0.01 parts of adhesive accelerator vinyltriethoxysilane; put them into a defoaming agent, mix and stir evenly to obtain sample 1.

[0030] Example 2

[0031] Weigh out 80 parts of acrylic modified silicone resin A, where n = 1000 for structure 1; 40 parts of acrylic modified silicone resin B, 0.3 parts of free radical initiator, and 0.06 parts of adhesive accelerator vinyltrimethoxysilane; put them into a defoaming agent and mix them evenly to obtain sample 2.

[0032] Example 3

[0033] Weigh out 60 parts of acrylic modified silicone resin A, where n = 800 for structure 1; 30 parts of acrylic modified silicone resin B, 0.2 parts of free radical initiator, and 0.03 parts of adhesive accelerator vinyltrimethoxysilane; put them into a defoaming agent and mix them evenly to obtain sample 3.

[0034] Example 4

[0035] Weigh out 60 parts of acrylic modified silicone resin A, where n = 1000 for structure 1; 40 parts of acrylic modified silicone resin B, 0.3 parts of free radical initiator, and 0.04 parts of adhesive accelerator vinyltriethoxysilane; put them into a defoaming agent, mix and stir evenly to obtain sample 4.

[0036] Comparative Example 1

[0037] Commercially available UV-curable acrylic adhesive.

[0038] Comparative Example 2

[0039] Commercially available heat-cured organic silicone adhesive.

[0040] Test method:

[0041] 1. Tensile strength and elongation at break: Specimens were prepared and measured according to GB / T 528, and adhesive samples with a thickness of 2 mm were made.

[0042] 2. Shear strength test:

[0043] Prepare standard shear specimens according to the method specified in GB / T 7124. Select the test adhesive material according to the actual bonding surface material. The thickness should be consistent between groups, and 0.2 mm is recommended. It can be controlled by spacer wires (iron or copper wires with fixed thickness, or pressure-sensitive tape with fixed thickness) or small glass balls. If wires are used, they should be parallel to the direction of force to avoid introducing errors in the experiment.

[0044] Choose appropriate tensile testing machine parameters: the breaking load should be between 10% and 80% of the maximum load of the tensile testing machine, and the response time of the testing machine should be short enough to ensure the accuracy of the fracture time determination. The tensile speed is recommended to be 10 mm / min.

[0045] 3. Thermal shock resistance test

[0046] Referring to GB / T 2423.3 Environmental Testing Part 2: Test Methods Test Cab: Constant Humidity and Heat Test, the sample was placed in a constant temperature and humidity chamber with a temperature of 85±3℃ and a humidity of 82%~88%RH for 1000 hours, then removed and placed at room temperature for another 24 hours before testing.

[0047] 4. Resistance to damp heat

[0048] Prepare relevant test strips. All samples must be fully cured in laboratory conditions before testing. Referring to GB / T 2423.22 Environmental Testing Part 2: Test Methods Test N: Temperature Change, place the samples in an alternating temperature environment of -40℃ to 85℃, with the transition time between the two extreme temperatures within 3 minutes. Perform one cycle per hour, for a total of 1000 cycles. After removal, allow the samples to stand at room temperature for another 24 hours before testing.

[0049] The performance of the UV-curable silicone materials obtained from Examples 1, 2, 3, 4, Comparative Example 1, and Comparative Example 2, as tested, is shown in Table 1.

[0050] Table 1

[0051]

[0052]

[0053] The data in the table above show that the adhesive strength of the material prepared by this invention is comparable to that of ordinary UV adhesives, and far exceeds that of ordinary heat-cured silicone resins. In terms of adhesion, the adhesive prepared by this invention outperforms both commercially available UV adhesives and silicone resins. Furthermore, its resistance to thermal cycling and its retention rate of moisture and heat resistance are superior to UV adhesives and slightly higher than those of heat-cured silicone resins. This indicates that the UV-curable silicone resin prepared by this invention possesses both the rapid curing properties of UV adhesives and the excellent moisture and heat resistance and thermal shock resistance of silicone resins.

[0054] The above description is only a preferred embodiment of the present invention and is 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. A UV-curable silicone adhesive, characterized in that, It is composed of the following raw materials in parts by weight: 60-80 parts of acrylic modified silicone resin A, 20-40 parts of acrylic modified silicone resin B, 0.1-0.3 parts of free radical initiator, and 0.01-0.06 parts of adhesion promoter; The preparation method of the acrylic-modified silicone resin A is as follows: Step 1: Add 1 mol of allyl alcohol glycidyl ether to a three-necked flask, add chloroplatinic acid as a catalyst (chloroplatinic acid accounts for 0.01%-0.05% of the total weight of the reaction system), add cyclohexane of equal mass to allyl alcohol glycidyl ether, stir evenly and heat to 50°C, add 0.5 mol of hydrogen-terminated silicone oil dropwise, after the addition is complete, heat to 80-100°C and reflux for 3-5 hours, then stop the reaction and switch to vacuum distillation to remove the solvent and allyl alcohol glycidyl ether to obtain intermediate 1; Step 2: Add intermediate 1 and 1.2 mol of acrylic acid to a three-necked flask, add 1%-5% of the total reaction system weight of the catalyst triphenylphosphine, heat to 120℃, react for 5 h, and then react under vacuum for 3 h to obtain acrylic acid modified organosilicon resin A. The preparation method of the acrylic-modified silicone resin B is as follows: Step 1: Add 1 mol of allyl alcohol glycidyl ether to a three-necked flask, add chloroplatinic acid as a catalyst (chloroplatinic acid accounts for 0.01%-0.03% of the total weight of the reaction system), add cyclohexane of equal mass to allyl alcohol glycidyl ether, stir evenly and heat to 50℃-80℃, add 0.2 mol of tetramethylcyclotetrasiloxane dropwise, after the addition is complete, heat to 80-100℃ and reflux for 3-6 hours, then stop the reaction and switch to vacuum distillation to remove the solvent and allyl alcohol glycidyl ether to obtain intermediate 2; Step 2: Add intermediate 2 and 1.2-1.4 mol of acrylic acid to a three-necked flask, add 1%-5% of the total reaction system weight of the catalyst triphenylphosphine, heat to 90-120℃, react for 3-5 hours, and then react under vacuum for 3-5 hours to obtain acrylic acid modified organosilicon resin B.

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