Heat-resistant silicone pressure-sensitive adhesive and method for preparing the same

Abstract

The application discloses a kind of heat-resistant silicone pressure-sensitive adhesive and preparation method thereof, belong to the technical field of silicone pressure-sensitive adhesive. Including the following weight parts of raw materials: 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 whisker, 7-21 parts of modified carbon black, 70-90 parts of toluene, 0.3-0.5 parts of catalyst, 0.5-0.7 g hydrogen-containing silicone oil. The prepared silicone pressure-sensitive adhesive is crosslinked by addition, forming a three-dimensional network structure, improving the heat resistance and mechanical properties of pressure-sensitive adhesive;Potassium titanate whisker is added in the raw material, which further improves the heat resistance and mechanical properties of pressure-sensitive adhesive;Among them, the modified carbon black has good compatibility with the silicone matrix, which significantly enhances the antistatic, heat-resistant and mechanical properties of the pressure-sensitive adhesive, and the performance is stable;Therefore, the application has important application value in the technical field of silicone pressure-sensitive adhesive.

Description

Technical Field

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

[0002] With the rapid development of modern industry, pressure-sensitive adhesive (PSA), as an important functional material, has been widely used in many fields such as electronics, automobiles, aerospace, construction, and medical care. Pressure-sensitive adhesives have the characteristic of being able to achieve adhesion by applying slight pressure without the need for heating or solvents, so their performance directly affects the quality and reliability of end products. However, traditional pressure-sensitive adhesives often exhibit poor heat resistance when exposed to high-temperature environments, which limits their use in some special application scenarios, such as high-temperature electronic component packaging, fixing engine peripheral components, and labeling in high-temperature environments.

[0003] There are many types of pressure-sensitive adhesives (PSA), including acrylic, rubber, and silicone. Silicone PSA has attracted considerable attention due to its unique chemical structure. Compared to traditional acrylate or rubber-based PSAs, silicone PSAs offer superior low-temperature resistance, good electrical insulation, and excellent oxidation and UV resistance. These properties enable silicone PSAs to maintain stable bonding under extreme conditions, making them the material of choice for many high-end applications. However, despite their numerous advantages, silicone PSAs still face some pressing challenges in practical applications, particularly regarding heat resistance.

[0004] The common silicone pressure-sensitive adhesives on the market are mainly composed of polydimethylsiloxane (PDMS), cross-linking agents, catalysts and other additives. Although this type of material meets the basic heat resistance requirements to a certain extent, it may still experience problems such as decreased bonding strength, weakened cohesion, and even failure when exposed to high temperature environments for a long time (such as above 200°C). In addition, with the rapid development of electronic technology, microelectronics are becoming more and more sophisticated, and the damage caused by static electricity to electronic devices such as touch screens, chips, and large-scale integrated circuits is becoming more and more serious. Therefore, pressure-sensitive adhesives are also required to have antistatic properties. In order 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 demands in the field of silicone pressure-sensitive adhesive technology. 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 through the following technical solutions:

[0007] A method for preparing a heat-resistant silicone pressure-sensitive adhesive comprises the following steps:

[0008] Add terminal hydroxyl polydimethylsiloxane, methyl vinyl polysiloxane, vinyl MQ resin, potassium titanate whiskers, modified carbon black and toluene into a reactor, then perform mechanical stirring to fully disperse the raw materials, then introduce nitrogen into the reactor as a protective gas, then add a catalyst, and then increase the temperature to perform a reflux reaction. After the reaction is completed, add hydrogenated silicone oil and stir for 1-3 hours to obtain a heat-resistant silicone pressure-sensitive adhesive.

[0009] Furthermore, the raw materials are calculated in parts by weight as follows: 26-32 parts of terminal hydroxyl 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 parts of catalyst, and 0.5-0.7g of hydrogenated silicone oil.

[0010] Furthermore, the reflux reaction temperature is 130-150° C., and the time is 4-6 hours.

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

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

[0013] Furthermore, the modified carbon black is prepared by the following steps:

[0014] Step 1. Hexafluoroglutaryl chloride, aluminum chloride, 4-aminostyrene, and toluene were added to a three-necked flask equipped with a magnetic stirrer and a thermometer. After stirring and mixing, the apparatus was placed in a 50°C water bath for 4 hours. After the reaction was complete, the mixture was filtered and the solvent was removed by distillation under reduced pressure to obtain intermediate 1. The ratio of hexafluoroglutaryl chloride, aluminum chloride, 4-aminostyrene, and toluene was 29.2 g:0.3 g:11.9 g:100 mL.

[0015] Under the catalysis of aluminum chloride, hexafluoroglutaryl chloride and 4-aminostyrene undergo an amidation reaction. The molar ratio of hexafluoroglutaryl chloride to 4-aminostyrene is adjusted to close to 1:1 (hexafluoroglutaryl chloride is slightly excessive) to produce intermediate 1. The specific reaction process is shown below:

[0016]

[0017] Step 2, the intermediate product 1, aluminum chloride, 2,3-diaminonaphthalene and toluene are added to a three-necked flask equipped with a magnetic stirrer and a thermometer, and after stirring and mixing, the device is placed in a water bath, heated to 60 ° C, and stirred continuously. After the reaction is completed for 6 hours, the reaction is completed, filtered, and concentrated under reduced pressure to remove part of the solvent. Then, column chromatography is performed using a benzene-ethyl acetate (4:1, v / v) elution system, and the residual eluent is finally removed by reduced pressure distillation to obtain intermediate product 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;

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

[0019]

[0020] Step 3: After mixing the oxidized carbon black with toluene, ultrasonically treat for 30 minutes to uniformly disperse the oxidized carbon black, add the intermediate product 2 and dicyclohexylcarbodiimide, magnetically stir for 5 hours, place in a 65°C water bath and ultrasonicate for 5 hours, remove the water bath and magnetically stir at room temperature for 6 hours, filter, wash the filter residue with anhydrous ethanol several times, dry, and grind to obtain modified carbon black; the ratio of the oxidized carbon black, toluene, intermediate product 2, and dicyclohexylcarbodiimide is 1g:100mL:13.6g:4.3g;

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

[0022] Carbon black is a granular filler with a carbon content of 90-99%. It is a product obtained by 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 conductivity and can be used as a conductive filler. By grafting organic molecular chains on the surface of carbon black and modifying the carbon black, the compatibility of carbon black with the silicone matrix is ​​greatly improved, making it easier to disperse in the matrix, thereby greatly enhancing the mechanical properties and antistatic properties of the matrix. In addition, the grafted organic molecular chains also contain benzene rings, naphthalene rings, CF bonds and carbon-carbon double bonds, among which benzene rings and naphthalene rings are aromatic groups, and the π-π conjugated system in aromatic compounds It has high thermal stability and can effectively disperse heat, and the bond energy of the benzene ring is high, thereby improving the heat resistance of the matrix; in addition, in the introduced CF bond, the fluorine atom has high electronegativity and the bond energy of the CF bond is also high, the better the stability, the more it 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 bond can cross-link with the organosilicon matrix containing double bonds, further improving the heat resistance and mechanical strength of the matrix; finally, the modified carbon black can effectively prevent the diffusion and precipitation of small organic molecules through chemical grafting of surface organic molecular chains, thereby improving its stability in the composite system.

[0023] Beneficial effects of the present invention:

[0024] 1. The organosilicon pressure-sensitive adhesive prepared by the present invention forms a three-dimensional network structure through addition-type cross-linking, thereby 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 and is easier to perform, 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 by the present invention has stable and efficient heat resistance, antistatic and mechanical properties, and has important application value in the field of silicone pressure-sensitive adhesive technology. DETAILED DESCRIPTION

[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0029] Example 1

[0030] Preparation of modified carbon black:

[0031] Step 1: 29.2 g of hexafluoroglutaryl chloride, 0.3 g of aluminum chloride, 11.9 g of 4-aminostyrene, and 100 mL of toluene were added to a three-necked flask equipped with a magnetic stirrer and a thermometer. After stirring and mixing, the apparatus was placed in a 50° C. water bath for 4 hours. After the reaction was complete, the mixture was filtered and the solvent was removed by distillation under reduced pressure to obtain an intermediate product 1.

[0032] Step 2, 35.9g of intermediate product 1, 0.4g of aluminum chloride, 17.3g of 2,3-diaminonaphthalene and 100mL of toluene were added to a three-necked flask equipped with a magnetic stirrer and a thermometer, stirred and mixed evenly, and then placed in a water bath, heated to 60 ° C, stirred continuously, and reacted for 6 hours. After the reaction was completed, filtered, concentrated under reduced pressure to remove part of the solvent, and purified by column chromatography using a benzene-ethyl acetate (4:1, v / v) elution system, and finally removed the residual eluent by distillation under reduced pressure to obtain intermediate product 2;

[0033] Step 3. After mixing 1 g of oxidized carbon black with 100 mL of toluene, ultrasonically treat for 30 min to uniformly disperse the oxidized carbon black, add 13.6 g of intermediate product 2 and 4.3 g of dicyclohexylcarbodiimide, and magnetically stir for 5 h. Then, place it in a 65 ° C water bath and ultrasonicate for 5 h. Remove the water bath and magnetically stir at room temperature for 6 h. Filter, wash the filter residue with anhydrous ethanol several times, dry, and grind to obtain modified carbon black.

[0034] Example 2

[0035] Preparation of modified carbon black:

[0036] Step 1: 58.4 g of hexafluoroglutaryl chloride, 0.6 g of aluminum chloride, 23.8 g of 4-aminostyrene, and 200 mL of toluene were added to a three-necked flask equipped with a magnetic stirrer and a thermometer. After stirring and mixing, the apparatus was placed in a 50° C. water bath and kept warm for 4 hours. After the reaction was complete, the mixture was filtered and the solvent was removed by distillation under reduced pressure to obtain an intermediate product 1.

[0037] Step 2, 71.8g of intermediate product 1, 0.8g of aluminum chloride, 34.6g of 2,3-diaminonaphthalene and 200mL of toluene were added to a three-necked flask equipped with a magnetic stirrer and a thermometer, stirred and mixed evenly, and then placed in a water bath, heated to 60 ° C, stirred continuously, and reacted for 6 hours. After the reaction was completed, filtered, concentrated under reduced pressure to remove part of the solvent, and purified by column chromatography using a benzene-ethyl acetate (4:1, v / v) elution system, and finally removed the residual eluent by distillation under reduced pressure to obtain intermediate product 2;

[0038] Step 3: After mixing 2 g of oxidized carbon black with 200 mL of toluene, ultrasonically treat for 30 min to uniformly disperse the oxidized carbon black, add 27.2 g of intermediate product 2 and 8.6 g of dicyclohexylcarbodiimide, and magnetically stir for 5 h. Then, place in a 65 ° C water bath and ultrasonicate for 5 h. Remove the water bath and magnetically stir at room temperature for 6 h. Filter, wash the filter residue with anhydrous ethanol several times, dry, and grind to obtain modified carbon black.

[0039] Example 3

[0040] 26 g of hydroxy-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 were added to a reactor, followed by mechanical stirring to fully disperse the raw materials. Nitrogen was then introduced into the reactor as a protective gas, and 0.3 g of chloroplatinic acid was added. The temperature was then raised to reflux for 4 h at a reaction temperature of 130-150 ° C. After the reaction was completed, 0.5 g of hydrogenated silicone oil was added, and the mixture was stirred for 1 h to obtain a heat-resistant silicone pressure-sensitive adhesive.

[0041] Example 4

[0042] 29 g of hydroxy-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 modified carbon black obtained in Example 2, and 80 g of toluene were added to a reactor, followed by mechanical stirring to fully disperse the raw materials. Nitrogen was then introduced into the reactor as a protective gas, and 0.4 g of chloroplatinic acid was added. The temperature was then raised to reflux for 6 h at a reaction temperature of 150° C., and the reaction was completed. 0.6 g of hydrogenated silicone oil was added, and the mixture was stirred for 3 h to obtain a heat-resistant silicone pressure-sensitive adhesive.

[0043] Example 5

[0044] 32 g of hydroxy-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 obtained in Example 2, and 90 g of toluene were added to a reactor, followed by mechanical stirring to fully disperse the raw materials. Nitrogen was then introduced into the reactor as a protective gas, and 0.5 g of chloroplatinic acid was added. The temperature was then raised to reflux for 6 h at a reaction temperature of 150° C., and the reaction was completed. 0.7 g of hydrogenated silicone oil was added, and the mixture was stirred for 3 h to obtain a heat-resistant silicone pressure-sensitive adhesive.

[0045] Comparative Example 1

[0046] Ordinary carbon black of the same mass was used to replace the modified carbon black in Example 5, and the remaining steps were the same as in Example 5 to prepare a pressure-sensitive adhesive.

[0047] Comparative Example 2

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

[0049] Using a 100 μm polyimide film as the substrate, Examples 3, 4, and 5, and Comparative Examples 1 and 2 were coated onto the polyimide film. After drying, a pressure-sensitive adhesive sheet was obtained. The peel strength was then measured 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 sheet;

[0051] The sample was stuck on a stainless steel plate and then placed in a 300°C oven to measure the time required for the polyimide film to fall off the stainless steel plate.

[0052] After storing the samples of Examples 3, 4, and 5 at room temperature for 200 days, the samples were then attached to a stainless steel plate and placed in a 300°C oven 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 heat resistance, antistatic properties and mechanical properties of the pressure-sensitive adhesive prepared in the embodiment of the present invention are higher than those of the comparative example, and the performance is long-lasting and stable, which has important application value in the field of silicone pressure-sensitive adhesive technology.

[0056] Throughout the specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0057] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in similar ways. As long as they do not deviate from the invention or exceed the scope defined by the claims, they should all fall within the scope of protection 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: Adding hydroxy-terminated polydimethylsiloxane, methylvinylpolysiloxane, vinyl MQ resin, potassium titanate whiskers, modified carbon black and toluene into a reactor, followed by mechanical stirring to fully disperse the raw materials, introducing nitrogen into the reactor, adding a catalyst, and heating to perform a reflux reaction. After the reaction is complete, adding hydrogenated silicone oil and stirring again to obtain a heat-resistant silicone pressure-sensitive adhesive; Wherein, the modified carbon black is prepared by the following steps: Step 1, hexafluoroglutaryl chloride, aluminum chloride, 4-aminostyrene and toluene were added to a flask, stirred and mixed evenly, and the apparatus was placed in a 50°C water bath for 4 hours. After the reaction was complete, the mixture was filtered and distilled under reduced pressure to obtain intermediate 1; Step 2: Add the intermediate product 1, aluminum chloride, 2,3-diaminonaphthalene and toluene to a flask, stir and mix evenly, then place the device in a water bath, heat to 60°C, stir and react for 6 hours. After the reaction is complete, filter, concentrate under reduced pressure, purify by column chromatography, and distill under reduced pressure to obtain the intermediate product 2; Step 3: After mixing the oxidized carbon black with toluene, ultrasonically treat the mixture, add the intermediate product 2 and dicyclohexylcarbodiimide, magnetically stir for 5 hours, place the mixture in a 65°C water bath and ultrasonicate for 5 hours, magnetically stir the mixture at room temperature for 6 hours, filter, wash, dry, and grind to obtain modified carbon black; Wherein, the ratio of hexafluoroglutaryl chloride, aluminum chloride, 4-aminostyrene, and toluene in step 1 is 29.2 g: 0.3 g: 11.9 g: 100 mL; the ratio of the intermediate product 1, aluminum chloride, 2,3-diaminonaphthalene, and toluene in step 2 is 35.9 g: 0.4 g: 17.3 g: 100 mL; the ratio of the oxidized carbon black, toluene, intermediate product 2, and dicyclohexylcarbodiimide in step 3 is 1 g: 100 mL: 13.6 g: 4.3 g; Among them, 26-32 parts of terminal hydroxyl 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 parts of catalyst, and 0.5-0.7g of hydrogenated silicone oil.

2. The method for preparing a heat-resistant silicone pressure-sensitive adhesive according to claim 1, wherein: The catalyst is a platinum-based catalyst.

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

4. A heat-resistant silicone pressure-sensitive adhesive, characterized in that: Prepared according to the method according to any one of claims 1 to 3.

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