UV modified organic silicon adhesive and preparation method thereof

Abstract

The invention belongs to the technical field of organic silicon adhesives, and particularly relates to a UV modified organic silicon adhesive and a preparation method thereof. The UV modified organic silicon adhesive comprises the following raw materials in parts by weight: 30-60 parts of acrylic acid modified organic silicon resin D; 30-60 parts of acrylic acid modified organic silicon resin E; and 0.1 to 0.3 part of a UV initiator. According to the invention, acrylic acid modified organic silicon resin is adopted as matrix resin, and the UV curing performance of vinyl can be utilized to achieve the purposes of rapid curing and improvement of initial adhesion strength; the presence of an organosilicon backbone can provide excellent aging resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of organic silicon adhesives, and in particular relates to a UV modified organic silicon adhesive and a preparation method thereof. Background Art

[0002] Conformal coating (moisture-proof, salt spray-proof and mildew-proof) is a functional material that provides insulation, heat resistance, weather resistance, wear resistance and other coating protection for precision circuit boards. It can effectively extend the service life of the device and improve its safety and reliability.

[0003] Epoxy resin conformal coating has a short application period, but has good moisture resistance, salt spray resistance and chemical resistance; silicone conformal coating is a soft elastic coating material with high operating temperature and good electrical insulation performance. It also has good chemical corrosion resistance and salt spray resistance, and is suitable for coating on the surface of high-heating components. Traditional condensation-type silicone resins mainly use isocyanate or alkoxy functional groups to react with moisture in the air to achieve cross-linking and curing. Isocyanate can react with water vapor at high temperature to form unstable amino acid intermediates, and after removing CO2, it continues to react with other isocyanate functional groups to achieve deep curing. Although the reactivity of the isocyanate group is high, the residual isocyanate group is highly toxic and does not meet environmental protection requirements; the alkoxy group, especially the methoxy group, has high chemical activity and can react with water molecules at room temperature to generate silanols. The latter is further polycondensed to obtain a film with excellent acid and alkali resistance, temperature resistance and water resistance. Whether it is isocyanate or alkoxy, condensation-type silicone resins have the disadvantage of long curing time, accompanied by the release of small molecular compounds. Compared with other curing methods, ultraviolet (UV) curing is energy-efficient, environmentally friendly, economical and versatile. It has a fast free radical curing speed, low photoinitiator price, and excellent surface performance of the cured film. It is the most widely used type of UV curing, but it has oxygen inhibition, poor adhesion, and volume shrinkage. Cationic photocuring does not have oxygen inhibition, and the volume shrinkage rate of the cured product is small and the adhesion is strong. At the same time, there is a "dark reaction", that is, cationic polymerization can continue after the light source is removed. Therefore, it is suitable for the curing of 3D parts and the varnishing of plastic pipes. Whether it is free radical or cationic curing, thin-layer products using UV curing have technical characteristics such as fast curing, low operating cost, high quality, clean and efficient, but for thicker coatings, non-illuminated areas or areas where UV light cannot penetrate, there is a situation of incomplete resin curing. The dual-curing system formed by combining UV curing with traditional curing methods such as thermal curing and moisture curing is expected to overcome the technical defects of a single curing method. Summary of the invention

[0004] In view of the above shortcomings of the prior art, the purpose of the present invention is to provide a UV modified silicone adhesive and a preparation method thereof. At present, the dual curing system has been gradually applied in the fields of liquid photosensitive solder resist coating, UV triple-proof adhesive liquid crystal panel bonding and frame packaging adhesive. In order to systematically explore the influence of factors such as silicone molecular structure and photoinitiator system on the curing rate and the performance of curing materials, the present invention studies and synthesizes alicyclic epoxy modified silicone resins, and explores the water absorption performance, heat resistance and mechanical properties of cationic UV light-wet dual curing silicone packaging materials.

[0005] To achieve the above objectives, the technical solutions adopted are:

[0006] The present invention provides a single-component UV modified silicone adhesive and a preparation method thereof, which has the following characteristics: 1. The viscosity is moderate and can be dispensed at room temperature; 2. The strength is quickly increased after UV irradiation curing, and the bonding strength can reach more than 2 MPa in 5 minutes, which can well improve the bonding force; 3. The cured product has high light transmittance and excellent aging performance; it has good temperature resistance and can maintain performance in a wide temperature range.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] One of the purposes of the present invention is to provide a UV modified silicone adhesive, comprising the following raw materials in parts by weight:

[0009] 30-60 parts of acrylic acid modified silicone resin D; 30-60 parts of acrylic acid modified silicone resin E; 0.1-0.3 parts of UV initiator.

[0010] Furthermore, the structure of the acrylic modified silicone resin D is:

[0011]

[0012] in,

[0013] n=1000-5000.

[0014] The preparation method of the acrylic acid-modified silicone resin D comprises the following steps:

[0015] (1) Add vinyl trimethoxysilane and 1 ppm of Custer catalyst to a reaction vessel, mix well, heat to 50-55° C., add reactant A-1 dropwise, keep warm at 75-85° C. for 1-3 hours after the addition is complete, stop the reaction and cool to obtain intermediate B-1, wherein the molar ratio of vinyl trimethoxysilane to reactant A-1 is 1:1;

[0016] (2) Add 10-20 mol of 1,1,3,3-tetramethyldisiloxane to a reaction vessel, add 10 ppm of a catalyst pentafluorophenylborane, mix well, dropwise add 1 mol of the intermediate B-1, continue the reaction for 2-3 hours after the dropwise addition is complete, and then remove small molecules by distillation under reduced pressure to obtain 1 mol of the intermediate C-1;

[0017] (3) Add 3 mol of 4-vinyl-1-cyclohexene-1,2-epoxy and 1 ppm of Custer catalyst to a reaction vessel, mix well, heat to 50-60°C, dropwise add 1 mol of intermediate C-1, keep at 80-90°C for 1-3 hours after the dropwise addition, stop the reaction and cool down to obtain product D-1, i.e., UV modified silicone adhesive D.

[0018] Its synthetic route is as follows:

[0019]

[0020] Furthermore, the structure of the acrylic modified silicone resin E is:

[0021]

[0022] in,

[0023] The preparation method of the acrylic acid-modified silicone resin E comprises the following steps:

[0024] Add 4-vinyl-1-cyclohexene-1,2-epoxy to a reaction container, add 1 ppm of Custer catalyst, mix evenly, heat to 50-60° C., add tetramethylcyclotetrasiloxane dropwise, keep warm at 75-85° C. for 1.5-3 hours after the addition is complete, stop the reaction and cool down to obtain a product, i.e., acrylic modified silicone resin E, wherein the molar ratio of the 4-vinyl-1-cyclohexene-1,2-epoxy to the added tetramethylcyclotetrasiloxane is 1:4.

[0025] Its synthetic route is as follows:

[0026]

[0027] Furthermore, the UV initiator is TPO ((2,4,6-trimethylbenzoyl) diphenylphosphine oxide) or TPOL (ethyl 2,4,6-trimethylbenzoyl phenylphosphonate).

[0028] The second object of the present invention is to provide a method for preparing the UV modified silicone adhesive, comprising the following steps:

[0029] Put 30-60 parts of acrylic modified silicone resin D, 30-60 parts of acrylic modified silicone resin E and 0.1-0.3 parts of UV initiator into a reaction container, raise the oil temperature to 60-70°C, vacuum and stir for half an hour, and then discharge the material.

[0030] Compared with the prior art, the present invention has the following beneficial effects: the present invention uses acrylic modified silicone resin as the main resin, and can utilize the UV curing performance of vinyl to achieve rapid curing and improve the initial adhesion strength; the presence of the silicone main chain can provide excellent aging resistance. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the technical solution of the present invention and to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, the present invention is further described in detail below in conjunction with embodiments.

[0032] Preparation Example 1

[0033] Preparation of acrylic acid modified silicone resin D:

[0034] Step 1: Take a 1L three-necked flask, add 1 mol of vinyltrimethoxysilane, add 1 ppm of Custer catalyst, add a magnet, mix well and heat to 50°C, add 1 mol of reactant A-1 (n=1000) dropwise, keep warm at 80°C for two hours after the addition is complete, stop the reaction and cool down to obtain 1 mol of intermediate B-1;

[0035] Step 2: Take a 1L three-necked flask, add 10 mol of 1,1,3,3-tetramethyldisiloxane, add 10 ppm of catalyst pentafluorophenylborane, add a magnet, mix well, add 1 mol of intermediate B-1 dropwise, continue to react for 2 hours after the addition is complete, and then remove small molecules by reduced pressure distillation to obtain 1 mol of intermediate C-1;

[0036] Step 3: Take a 1L three-necked flask, add 1 mol of 4-vinyl-1-cyclohexene-1,2-epoxy, add 1 ppm of Custer catalyst, add a magnet, mix evenly and heat to 50°C, add 1 mol of intermediate C-1 dropwise, keep the temperature at 80°C for two hours after the addition is complete, stop the reaction and cool down to obtain acrylic modified silicone resin D;

[0037] Preparation of acrylic acid modified silicone resin E

[0038] Take a 1L three-necked flask, add 4 mol of 4-vinyl-1-cyclohexene-1,2-epoxy, add 1 ppm of Custer catalyst, add a magnet, mix evenly and heat to 50°C, add 1 mol of the intermediate tetramethylcyclotetrasiloxane dropwise, keep warm at 80°C for two hours after the addition is complete, stop the reaction and cool down to obtain acrylic modified silicone resin E.

[0039] Preparation Example 2

[0040] Preparation of acrylic acid modified silicone resin D:

[0041] Step 1: Take a 1L three-necked flask, add 1 mol of vinyltrimethoxysilane, add 1 ppm of Custer catalyst, add a magnet, mix well and heat to 50°C, add 1 mol of reactant A-1 (n=5000) dropwise, keep at 80°C for two hours after the addition is complete, stop the reaction and cool down to obtain 1 mol of intermediate B-1;

[0042] Step 2: Take a 1L three-necked flask, add 10 mol of 1,1,3,3-tetramethyldisiloxane, add 10 ppm of catalyst pentafluorophenylborane, add a magnet, mix well, add 1 mol of intermediate B-1 dropwise, continue to react for 2 hours after the addition is complete, and then remove small molecules by reduced pressure distillation to obtain 1 mol of intermediate C-1;

[0043] Step 3: Take a 1L three-necked flask, add 1 mol of 4-vinyl-1-cyclohexene-1,2-epoxide, add 1 ppm of Castel catalyst, add a magnet, mix evenly and heat to 50°C, add 1 mol of intermediate C-1 dropwise, keep warm at 80°C for two hours after the addition is complete, stop the reaction and cool down to obtain acrylic modified silicone resin D.

[0044] Example 1

[0045] 40g of acrylic modified silicone resin D and 60g of acrylic modified silicone E of Preparation Example 1 and 0.1g of UV initiator TPO were placed in a three-necked flask, the oil temperature was raised to 60°C, vacuum was drawn to -0.09mpa, and the material was stirred for half an hour before discharging to obtain a UV modified silicone adhesive.

[0046] Example 2

[0047] 40g of acrylic modified silicone resin D and 50g of acrylic modified silicone E of Preparation Example 2 and 0.2g of UV initiator TPOL were put into a three-necked flask, the oil temperature was raised to 60°C, vacuum was drawn to -0.09mpa, and the material was stirred for half an hour to obtain a UV modified silicone adhesive.

[0048] Example 3

[0049] 30g of acrylic modified silicone resin D and 40g of acrylic modified silicone E of Preparation Example 1 and 0.3g of UV initiator TPO were placed in a three-necked flask, the oil temperature was raised to 60°C, vacuum was drawn to -0.09mpa, and the material was stirred for half an hour and then discharged to obtain a UV modified silicone adhesive.

[0050] Example 4

[0051] 50g of acrylic modified silicone resin D and 30g of acrylic modified silicone E of Preparation Example 2 and 0.1g of UV initiator TPOL were put into a three-necked flask, the oil temperature was raised to 60°C, vacuum was drawn to -0.09mpa, and the material was stirred for half an hour and discharged to obtain a UV modified silicone adhesive.

[0052] The UV modified silicone adhesives prepared in Examples 1-4 and the commercially available one-component silicone rubber in Comparative Example 1 were tested for bonding strength. The results are shown in Table 1.

[0053] Adhesion strength test: Use a dispensing machine to dispense the UV modified silicone adhesives of Examples 1-4 and the commercially available single-component silicone rubber of Comparative Example 1 at room temperature of 25°C onto a polycarbonate substrate with a width of about 2 mm. Then, another polycarbonate substrate is attached to the polycarbonate substrate, and the adhesive line is irradiated with a 365nm UV-LED light source with an irradiation energy of 3000mJ / cm 2 After the irradiation, the bonding strength was tested 2 minutes (representing the strength after light irradiation), 30 minutes, and 24 hours after dispensing. The moisture curing conditions were temperature 25°C and humidity 50% RH.

[0054] Table 1. Adhesive performance data of Examples 1-4 and Comparative Example 1

[0055]

[0056] 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 principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A UV modified silicone adhesive, characterized in that: The invention comprises the following raw materials in parts by weight: 30-60 parts of acrylic acid modified silicone resin D; 30-60 parts of acrylic acid modified silicone resin E; 0.1-0.3 parts of UV initiator.

2. The UV modified silicone adhesive according to claim 1, characterized in that: The structure of the acrylic modified silicone resin D is: in, n＝1000-5000。 3. The UV modified silicone adhesive according to claim 2, characterized in that: The preparation method of the acrylic acid-modified silicone resin D comprises the following steps: (1) Add vinyl trimethoxysilane and 1 ppm of Custer catalyst to a reaction vessel, mix well, heat to 50-55° C., add reactant A-1 dropwise, keep warm at 75-85° C. for 1-3 hours after the addition is complete, stop the reaction and cool to obtain intermediate B-1, wherein the molar ratio of vinyl trimethoxysilane to reactant A-1 is 1:1; (2) Add 10-20 mol of 1,1,3,3-tetramethyldisiloxane to a reaction vessel, add 10 ppm of a catalyst pentafluorophenylborane, mix well, dropwise add 1 mol of the intermediate B-1, continue the reaction for 2-3 hours after the dropwise addition is complete, and then remove small molecules by distillation under reduced pressure to obtain 1 mol of the intermediate C-1; (3) Add 3 mol of 4-vinyl-1-cyclohexene-1,2-epoxy and 1 ppm of Custer catalyst to a reaction vessel, mix well, heat to 50-60°C, dropwise add 1 mol of intermediate C-1, keep the temperature at 80-90°C for 1-3 hours after the dropwise addition is completed, stop the reaction and cool down to obtain the product, namely, UV modified silicone adhesive D.

4. The UV modified silicone adhesive according to claim 1, characterized in that: The structure of the acrylic modified silicone resin E is: in, 5. The UV modified silicone adhesive according to claim 4, characterized in that: The preparation method of the acrylic acid-modified silicone resin E comprises the following steps: Add 4-vinyl-1-cyclohexene-1,2-epoxy to a reaction container, add 1 ppm of Custer catalyst, mix evenly, heat to 50-60° C., add tetramethylcyclotetrasiloxane dropwise, keep warm at 75-85° C. for 1.5-3 hours after the addition is complete, stop the reaction and cool down to obtain a product, i.e., acrylic modified silicone resin E, wherein the molar ratio of the 4-vinyl-1-cyclohexene-1,2-epoxy to the added tetramethylcyclotetrasiloxane is 1:

4.

6. The UV modified silicone adhesive according to claim 1, characterized in that: The UV initiator is TPO or TPOL.

7. A method for preparing the UV modified silicone adhesive according to any one of claims 1 to 6, characterized in that: The following steps are involved: 30-60 parts of acrylic modified silicone resin D, 30-60 parts of acrylic modified silicone resin E and 0.1-0.3 parts of UV initiator are placed in a reaction container, the oil temperature is raised to 60-70° C., vacuuming and stirring to obtain the product.

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