Heat-resistant organic silicon pressure-sensitive adhesive and preparation method thereof

Abstract

The invention discloses a heat-resistant organic silicon pressure-sensitive adhesive and a preparation method thereof, and belongs to the technical field of organic silicon pressure-sensitive adhesives. Comprising the following raw materials in parts by weight: 26 to 32 parts of hydroxyl-terminated polydimethylsiloxane, 22 to 30 parts of methyl vinyl polysiloxane, 36 to 42 parts of vinyl MQ resin, 12 to 18 parts of potassium titanate whisker, 7 to 21 parts of modified carbon black, 70 to 90 parts of toluene, 0.3 to 0.5 part of a catalyst and 0.5 to 0.7 g of hydrogen-containing silicone oil. According to the prepared organic silicon pressure-sensitive adhesive, a three-dimensional network structure is formed through addition type crosslinking, so that the heat resistance and the mechanical property of the pressure-sensitive adhesive are improved; the potassium titanate whiskers are added into the raw materials, so that the heat resistance and the mechanical property of the pressure-sensitive adhesive are further improved; wherein the modified carbon black has good compatibility with an organic silicon matrix, so that the antistatic, heat-resistant and mechanical properties of the pressure-sensitive adhesive are remarkably enhanced, and the performance is stable; therefore, the organic silicon pressure-sensitive adhesive has important application value in the technical field of organic silicon pressure-sensitive adhesives.

Description

Technical Field

[0001] The present invention belongs to the technical field of silicone pressure-sensitive adhesives, and specifically, relates to a heat-resistant silicone pressure-sensitive adhesive and a preparation method thereof. Background Art

[0002] With the rapid development of modern industry, pressure-sensitive adhesives (PSA) as an important functional material have been widely used in many fields such as electronics, automotive, aerospace, construction, and medical. Pressure-sensitive adhesives have the characteristic of achieving adhesion by applying slight pressure without heating or solvents, so their performance directly affects the quality and reliability of end products. However, traditional pressure-sensitive adhesives often show poor heat resistance when facing high-temperature environments, which limits their use in some special application scenarios, such as high-temperature electronic component encapsulation, fixing of engine peripheral components, and label identification in high-temperature environments.

[0003] There are various types of pressure-sensitive adhesives, including acrylate pressure-sensitive adhesives, rubber-based pressure-sensitive adhesives, silicone pressure-sensitive adhesives, etc. Among them, silicone pressure-sensitive adhesives have attracted much attention due to their unique chemical structure. Compared with traditional acrylate or rubber-based pressure-sensitive adhesives, silicone pressure-sensitive adhesives have excellent low-temperature resistance, good electrical insulation, excellent antioxidant and anti-ultraviolet capabilities. These characteristics enable silicone pressure-sensitive adhesives to maintain stable adhesive performance under extreme conditions and become the preferred material for many high-end application fields. However, despite the many advantages of silicone pressure-sensitive adhesives, there are still some problems to be solved in their practical applications, especially in terms of heat resistance.

[0004] Common silicone pressure-sensitive adhesives on the market currently mainly consist of polydimethylsiloxane (PDMS), crosslinking agents, catalysts, and other additives. Although such materials meet the basic heat resistance requirements to a certain extent, when exposed to high-temperature environments for a long time (such as above 200 °C), problems such as a decrease in adhesive strength, weakening of cohesion, and even failure may still occur. In addition, with the rapid development of electronic technology, microelectronics is becoming more and more precise, and the damage caused by static electricity to electronic devices such as touchscreens, chips, and large-scale integrated circuits is becoming more and more serious. Therefore, it is also necessary for pressure-sensitive adhesives to have antistatic properties. To solve the above problems, it is urgent to invent a silicone pressure-sensitive adhesive with antistatic and heat-resistant properties to meet the higher requirements in the technical field of silicone pressure-sensitive adhesives. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and provide a heat-resistant silicone pressure-sensitive adhesive and a preparation method thereof.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A preparation method of a heat-resistant silicone pressure-sensitive adhesive, comprising the following steps:

[0008] Add the hydroxyl-terminated polydimethylsiloxane, methyl vinyl polysiloxane, vinyl MQ resin, potassium titanate whiskers, modified carbon black and toluene into a reaction kettle, then carry out mechanical stirring. After the raw materials are fully dispersed, introduce nitrogen into the reaction kettle as a protective gas, then add a catalyst, and then raise the temperature for reflux reaction. After the reaction is completed, add hydrogen-containing silicone oil and stir for 1-3 h to obtain the heat-resistant silicone pressure-sensitive adhesive.

[0009] Further, the raw materials are as follows by weight: 26-32 parts of hydroxyl-terminated polydimethylsiloxane, 22-30 parts of methyl vinyl polysiloxane, 36-42 parts of vinyl MQ resin, 12-18 parts of potassium titanate whiskers, 7-21 parts of modified carbon black, 70-90 parts of toluene, 0.3-0.5 part of catalyst, 0.5-0.7 g of hydrogen-containing silicone oil.

[0010] Further, the temperature of the reflux reaction is 130-150 °C and the time is 4-6 h.

[0011] Further, the catalyst is a platinum-based catalyst.

[0012] Under the action of the platinum-based catalyst and the hydrogen-containing silicone oil, the prepared silicone pressure-sensitive adhesive undergoes crosslinking to form a three-dimensional network structure, improving the heat resistance and mechanical properties of the pressure-sensitive adhesive; adding potassium titanate whiskers, as a kind of short fiber, has good high-temperature resistance and high strength, further improving the heat resistance and mechanical properties of the pressure-sensitive adhesive.

[0013] Further, the modified carbon black is prepared through the following steps:

[0014] Step 1: Add hexafluoroglutaroyl chloride, aluminum chloride, 4-aminostyrene and toluene into a three-necked flask equipped with a magnetic stirrer and a thermometer. After stirring and mixing evenly, keep the device in a water bath at 50 °C for 4 h. After the reaction is completed, filter and remove the solvent by vacuum distillation to obtain intermediate product 1; the dosage ratio of hexafluoroglutaroyl chloride, aluminum chloride, 4-aminostyrene and toluene is 29.2 g: 0.3 g: 11.9 g: 100 mL;

[0015] Under the catalysis of aluminum chloride, hexafluoroglutaroyl chloride and 4-aminostyrene undergo an amidation reaction. By adjusting the molar ratio of hexafluoroglutaroyl chloride to 4-aminostyrene to be close to 1:1 (hexafluoroglutaroyl chloride is slightly in excess), intermediate product 1 is generated; the specific reaction process is as follows:

[0016]

[0017] Step 2: Add intermediate 1, aluminum chloride, 2,3-diaminonaphthalene, and toluene into a three-necked flask equipped with a magnetic stirrer and a thermometer. After stirring and mixing evenly, place the device in a water bath and heat it to 60 °C. Continuously stir. After reacting for 6 h, the reaction is completed. Filter, and after concentrating under reduced pressure to remove part of the solvent, perform column chromatography purification using a benzene-ethyl acetate (4:1, v / v) elution system. Finally, remove the residual eluent by distillation under reduced pressure to obtain intermediate 2. The dosage ratio of intermediate 1, aluminum chloride, 2,3-diaminonaphthalene, and toluene is 35.9 g:0.4 g:17.3 g:100 mL;

[0018] Under the catalysis of aluminum chloride, intermediate 1 and 2,3-diaminonaphthalene undergo an amidation reaction. By adjusting the molar ratio of intermediate 1 to 2,3-diaminonaphthalene to be close to 1:1 (2,3-diaminonaphthalene is slightly in excess), intermediate 2 is generated. The specific reaction process is as follows:

[0019]

[0020] Step 3: Mix oxidized carbon black with toluene and ultrasonically treat it for 30 min to disperse the oxidized carbon black evenly. Add intermediate 2 and dicyclohexylcarbodiimide, and magnetically stir for 5 h. Then place it in a 65 °C water bath and ultrasonically treat for 5 h. Remove the water bath and magnetically stir at room temperature for 6 h. Filter, wash the filter cake with absolute ethanol multiple times, dry, and grind to obtain modified carbon black. The dosage ratio of oxidized carbon black, toluene, intermediate 2, and dicyclohexylcarbodiimide is 1 g:100 mL:13.6 g:4.3 g;

[0021] The surface of oxidized carbon black contains a large number of oxygen functional groups, which can react with the amino group in the molecule of intermediate 2 under the catalysis of dicyclohexylcarbodiimide to graft organic molecules on the surface of oxidized carbon black, obtaining modified carbon black;

[0022] Carbon black is a granular filler with a carbon content of 90-99%. It is a product obtained by the thermal decomposition of carbon-containing substances such as coal, natural gas, and fuel oil. It has a reinforcing effect on the silicone matrix. In addition, carbon black has excellent electrical conductivity and can be used as a conductive filler. By grafting organic molecular chains on the surface of carbon black, the carbon black is modified, greatly improving the compatibility of carbon black with the silicone matrix, making it easier to disperse in the matrix, thereby significantly enhancing the mechanical properties and antistatic properties of the matrix. Moreover, the grafted organic molecular chains contain benzene rings, naphthalene rings, C-F bonds, and carbon-carbon double bonds. Among them, benzene rings and naphthalene rings belong to aryl groups. The π-π conjugate system in aromatic compounds has high thermal stability, which can effectively disperse heat, and the bond energy of the benzene ring is relatively high, thus improving the heat resistance of the matrix. In addition, in the introduced C-F bonds, fluorine atoms have high electronegativity and the bond energy of C-F bonds is also high, with better stability, which can shield and protect the carbon chain, reduce the surface free energy of the matrix, and significantly improve the heat resistance of the matrix. In addition, the introduced carbon-carbon double bonds can crosslink with the silicone matrix containing double bonds, further enhancing the heat resistance and mechanical strength of the matrix. Finally, through the chemical grafting of the surface organic molecular chains of the modified carbon black, the diffusion and precipitation behavior of organic small molecules can be effectively prevented, thereby improving its stability in the composite system.

[0023] Advantages of the present invention:

[0024] 1. The silicone pressure-sensitive adhesive prepared in the present invention forms a three-dimensional network structure through addition crosslinking, improving the heat resistance and mechanical properties of the pressure-sensitive adhesive;

[0025] 2. Adding potassium titanate whiskers to the raw materials further improves the heat resistance and mechanical properties of the pressure-sensitive adhesive;

[0026] 3. By modifying carbon black, compared with ordinary carbon black, it has better compatibility with the silicone matrix, its performance is easier to play, significantly enhancing the antistatic, heat resistance, and mechanical properties of the pressure-sensitive adhesive, and the performance is stable;

[0027] In summary, the pressure-sensitive adhesive prepared in the present invention has stable and efficient heat resistance, antistatic property, and mechanical properties, and has important application value in the technical field of silicone pressure-sensitive adhesives. Specific embodiments

[0028] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

[0029] Example 1

[0030] Preparation of modified carbon black:

[0031] Step 1: Add 29.2 g of hexafluoroglutaroyl chloride, 0.3 g of aluminum chloride, 11.9 g of 4-aminostyrene, and 100 mL of toluene into a three-necked flask equipped with a magnetic stirrer and a thermometer. After stirring and mixing evenly, keep the device in a water bath at 50 °C for 4 h for heat preservation reaction. After the reaction is completed, filter, and remove the solvent by vacuum distillation to obtain intermediate 1;

[0032] Step 2: Add 35.9 g of intermediate 1, 0.4 g of aluminum chloride, 17.3 g of 2,3-diaminonaphthalene, and 100 mL of toluene into a three-necked flask equipped with a magnetic stirrer and a thermometer. After stirring and mixing evenly, place the device in a water bath, heat up to 60 °C, and continuously stir. After reacting for 6 h, the reaction is completed. Filter, remove part of the solvent by vacuum concentration, and then carry out column chromatography purification using a benzene-ethyl acetate (4:1, v / v) elution system. Finally, remove the residual eluent by vacuum distillation to obtain intermediate 2;

[0033] Step 3: Mix 1 g of oxidized carbon black with 100 mL of toluene, and ultrasonically treat for 30 min to disperse the oxidized carbon black evenly. Add 13.6 g of intermediate 2 and 4.3 g of dicyclohexylcarbodiimide, stir magnetically for 5 h, then place it in a water bath at 65 °C and ultrasonically treat for 5 h. Then remove the water bath and stir magnetically at room temperature for 6 h. Filter, wash the filter residue with absolute ethanol for multiple times, dry, and grind to obtain the modified carbon black.

[0034] Example 2

[0035] Preparation of modified carbon black:

[0036] Step 1: Add 58.4 g of hexafluoroglutaroyl chloride, 0.6 g of aluminum chloride, 23.8 g of 4-aminostyrene, and 200 mL of toluene into a three-necked flask equipped with a magnetic stirrer and a thermometer. After stirring and mixing evenly, keep the device in a water bath at 50 °C for 4 h for heat preservation reaction. After the reaction is completed, filter, and remove the solvent by vacuum distillation to obtain intermediate 1;

[0037] Step 2: Add 71.8 g of intermediate 1, 0.8 g of aluminum chloride, 34.6 g of 2,3-diaminonaphthalene, and 200 mL of toluene into a three-necked flask equipped with a magnetic stirrer and a thermometer. After stirring and mixing evenly, place the device in a water bath, heat up to 60 °C, and continuously stir. After reacting for 6 h, the reaction is completed. Filter, remove part of the solvent by vacuum concentration, and then carry out column chromatography purification using a benzene-ethyl acetate (4:1, v / v) elution system. Finally, remove the residual eluent by vacuum distillation to obtain intermediate 2;

[0038] Step 3: Mix 2 g of oxidized carbon black with 200 mL of toluene, and perform ultrasonic treatment for 30 min to uniformly disperse the oxidized carbon black. Then add 27.2 g of intermediate product 2 and 8.6 g of dicyclohexylcarbodiimide, magnetically stir for 5 h, place it in a 65°C water bath and perform ultrasonic treatment for 5 h. Then remove the water bath and magnetically stir at room temperature for 6 h. Filter by suction, wash the filter residue with absolute ethanol multiple times, dry, grind, and obtain modified carbon black.

[0039] Example 3

[0040] Add 26 g of hydroxyl-terminated polydimethylsiloxane (molecular weight of 200,000), 22 g of methylvinylpolysiloxane (molecular weight of 150,000), 36 g of vinyl MQ resin (molecular weight of 5000), 12 g of potassium titanate whiskers, 7 g of the modified carbon black prepared in Example 1, and 70 g of toluene into a reaction kettle. Then perform mechanical stirring to fully disperse the raw materials. Then introduce nitrogen into the reaction kettle as a protective gas, and then add 0.3 g of chloroplatinic acid. Then raise the temperature for reflux reaction at a temperature of 130 - 150°C for 4 h. After the reaction is completed, add 0.5 g of hydrogen-containing silicone oil and stir for 1 h to obtain a heat-resistant silicone pressure-sensitive adhesive.

[0041] Example 4

[0042] Add 29 g of hydroxyl-terminated polydimethylsiloxane (molecular weight of 200,000), 26 g of methylvinylpolysiloxane (molecular weight of 150,000), 39 g of vinyl MQ resin (molecular weight of 5000), 15 g of potassium titanate whiskers, 14 g of the modified carbon black prepared in Example 2, and 80 g of toluene into a reaction kettle. Then perform mechanical stirring to fully disperse the raw materials. Then introduce nitrogen into the reaction kettle as a protective gas, and then add 0.4 g of chloroplatinic acid. Then raise the temperature for reflux reaction at a temperature of 150°C for 6 h. After the reaction is completed, add 0.6 g of hydrogen-containing silicone oil and stir for 3 h to obtain a heat-resistant silicone pressure-sensitive adhesive.

[0043] Example 5

[0044] Add 32 g of hydroxyl-terminated polydimethylsiloxane (molecular weight of 200,000), 30 g of methylvinylpolysiloxane (molecular weight of 150,000), 42 g of vinyl MQ resin (molecular weight of 5000), 12 - 18 g of potassium titanate whiskers, 21 g of the modified carbon black prepared in Example 2, and 90 g of toluene into a reaction kettle. Then perform mechanical stirring to fully disperse the raw materials. Then introduce nitrogen into the reaction kettle as a protective gas, and then add 0.5 g of chloroplatinic acid. Then raise the temperature for reflux reaction at a temperature of 150°C for 6 h. After the reaction is completed, add 0.7 g of hydrogen-containing silicone oil and stir for 3 h to obtain a heat-resistant silicone pressure-sensitive adhesive.

[0045] Comparative Example 1

[0046] Use ordinary carbon black of the same quality to replace the modified carbon black in Example 5, and the remaining steps are the same as those in Example 5 to prepare the pressure-sensitive adhesive.

[0047] Comparative Example 2

[0048] Use a commercially available silicone pressure-sensitive adhesive.

[0049] Using a 100-μm polyimide film as the substrate, coat the pressure-sensitive adhesives of Examples 3, 4, and 5, and Comparative Examples 1 and 2 on the polyimide film. After drying, obtain pressure-sensitive adhesive sheets, and then measure the peel strength using the national standard GB / T 2792 "Test Method for 180° Peel Strength of Pressure-Sensitive Adhesive Tapes";

[0050] Use a resistivity tester to test the surface resistance of the pressure-sensitive adhesive sheets;

[0051] Stick the specimen on a stainless steel plate, and then place it in an oven at 300°C to measure the time required for the polyimide film to fall off the stainless steel plate;

[0052] After storing Examples 3, 4, and 5 at room temperature for 200 days, stick the specimen on a stainless steel plate, and then place it in an oven at 300°C to measure the time required for the polyimide film to fall off the stainless steel plate;

[0053] The measured results are shown in the following table:

[0054]

[0055] As can be seen from the above table, the pressure-sensitive adhesives prepared in the examples of the present invention have higher heat resistance, antistatic properties, and mechanical properties than the comparative examples, and the properties are long-term stable, having important application value in the technical field of silicone pressure-sensitive adhesives.

[0056] In the description of the specification, the description of reference terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0057] The above content is only an example and illustration of the present invention. Those skilled in the art of the present technology make various modifications or supplements or use similar methods to replace the specific embodiments described, as long as they do not deviate from the invention or exceed the scope defined by the claims of the present invention, they should all belong to the protection scope of the present invention.

Claims

1. A method for preparing a heat-resistant silicone pressure-sensitive adhesive, characterized in that: The following steps are involved: Add terminal hydroxyl polydimethylsiloxane, methyl vinyl polysiloxane, vinyl MQ resin, potassium titanate whisker, modified carbon black and toluene into a reactor, and then perform mechanical stirring to fully disperse the raw materials. Then, introduce nitrogen into the reactor, add a catalyst, and heat up to perform a reflux reaction. After the reaction is completed, add hydrogenated silicone oil and stir to obtain a heat-resistant silicone pressure-sensitive adhesive.

2. The method for preparing a heat-resistant silicone pressure-sensitive adhesive according to claim 1, characterized in that: The raw materials are calculated in parts by weight as follows: 26-32 parts of terminal hydroxyl polydimethylsiloxane, 22-30 parts of methylvinyl polysiloxane, 36-42 parts of vinyl MQ resin, 12-18 parts of potassium titanate whiskers, 7-21 parts of modified carbon black, 70-90 parts of toluene, 0.3-0.5 parts of catalyst, and 0.5-0.7g of hydrogenated silicone oil.

3. The method for preparing a heat-resistant silicone pressure-sensitive adhesive according to claim 1, characterized in that: The modified carbon black is prepared by the following steps: Step 1, adding hexafluoroglutaryl chloride, aluminum chloride, 4-aminostyrene and toluene into a flask, stirring and mixing evenly, placing the device in a 50° C. water bath condition, keeping the temperature for 4 hours, filtering and distilling under reduced pressure to obtain an intermediate product 1 after the reaction is completed; Step 2, add the intermediate product 1, aluminum chloride, 2,3-diaminonaphthalene and toluene into a flask, stir and mix evenly, then place the device in a water bath, heat to 60°C, stir and react for 6 hours, filter, concentrate under reduced pressure, purify by column chromatography, and distill under reduced pressure to obtain the intermediate product 2; Step 3: Mix the oxidized carbon black and toluene, perform ultrasonic treatment, add the intermediate 2 and dicyclohexylcarbodiimide, and magnetically stir for 5 hours. Then, place the mixture in a 65°C water bath and perform ultrasonic treatment for 5 hours. Then, perform magnetic stirring at room temperature for 6 hours, filter, wash, dry, and grind to obtain modified carbon black.

4. The method for preparing a heat-resistant silicone pressure-sensitive adhesive according to claim 3, characterized in that: In step 1, the ratio of hexafluoroglutaryl chloride, aluminum chloride, 4-aminostyrene and toluene is 29.2 g: 0.3 g: 11.9 g: 100 mL.

5. The method for preparing a heat-resistant silicone pressure-sensitive adhesive according to claim 3, characterized in that: In step 2, the ratio of the amount of intermediate product 1, aluminum chloride, 2,3-diaminonaphthalene and toluene is 35.9 g: 0.4 g: 17.3 g: 100 mL.

6. The method for preparing a heat-resistant silicone pressure-sensitive adhesive according to claim 3, characterized in that: In step 3, the ratio of the amount of oxidized carbon black, toluene, intermediate product 2, and dicyclohexylcarbodiimide is 1 g:100 mL:13.6 g:4.3 g.

7. The method for preparing a heat-resistant silicone pressure-sensitive adhesive according to claim 1, characterized in that: The catalyst is a platinum-based catalyst.

8. The method for preparing a heat-resistant silicone pressure-sensitive adhesive according to claim 1, characterized in that: The temperature of the reflux reaction is 130-150° C. and the time is 4-6 hours.

9. A heat-resistant silicone pressure-sensitive adhesive, characterized in that: Prepared according to the method according to any one of claims 1 to 8.

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