Preparation method of damp-heat-resistant organic silicon pressure-sensitive adhesive

Abstract

The invention discloses a preparation method of a damp-heat-resistant organic silicon pressure-sensitive adhesive. The method comprises the following steps: 1) respectively dissolving hydroxyl-terminated polysiloxane and MQ resin in a diluent, and uniformly mixing the hydroxyl-terminated polysiloxane and the MQ resin; (2) adding a catalyst into the reaction liquid, heating to 40-200 DEG C, and carrying out reflux reaction for 2-24 hours; 3) after the reaction, controlling the temperature to 25-90 DEG C, adding a neutralizer, uniformly mixing, then adding a rare earth stabilizer, and uniformly mixing; and 4) continuously adding an end-capping reagent, and reacting at 60-180 DEG C to obtain the organic silicon pressure-sensitive adhesive.

Description

Technical Field

[0001] The invention relates to a polymer material, in particular to a method for preparing a moisture-heat resistant organic silicon pressure-sensitive adhesive. Background Art

[0002] Traditional organic pressure-sensitive adhesives, such as acrylic pressure-sensitive adhesives, have a maximum heat resistance of less than 150°C and a minimum operating temperature of basically above 0°C, while the operating temperature range of silicone pressure-sensitive adhesives is -66°C to 300°C, with excellent high temperature resistance. Silicone pressure-sensitive adhesives have good adhesion to low surface energy materials such as fluoroplastic substrates and silicone substrates, and have characteristics that traditional organic pressure-sensitive adhesive materials do not have, so they are more widely used.

[0003] However, silicone pressure-sensitive adhesives will undergo side reactions such as chain breakage and biting under high temperature and high humidity operating environments, and the degradation reaction will be aggravated, resulting in the inability of silicone pressure-sensitive adhesives to meet the needs of special application scenarios for a long time. This is manifested in the deterioration of the performance of the pressure-sensitive adhesive under high temperature and high humidity environments, and the appearance of residual adhesive on steel plates.

[0004] Existing technologies such as CN113105862A and CN107267114A have proposed different solutions for preparing heat-resistant silicone pressure-sensitive adhesives, but none of them can solve the problems existing in using the adhesives in high temperature and high humidity environments. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method for preparing a moisture-heat resistant organic silicone pressure-sensitive adhesive.

[0006] A method for preparing a moisture-heat resistant silicone pressure-sensitive adhesive comprises the following steps:

[0007] 1) Dissolve the hydroxyl-terminated polysiloxane and MQ resin in diluent respectively, and then mix the two evenly;

[0008] 2) Add a catalyst to the reaction solution, raise the temperature to 40-200°C, and reflux for 2-24 hours;

[0009] 3) After the reaction, the temperature is controlled to 25-90°C, a neutralizer is added, and the mixture is mixed evenly, and then a rare earth stabilizer is added and the mixture is mixed evenly;

[0010] 4) Continue to add the end-capping agent and react at 60-180° C. to obtain the silicone pressure-sensitive adhesive.

[0011] The inventors have found through continuous research that the residual hydroxyl group in the pressure-sensitive adhesive is the main factor that causes the deterioration of its aging resistance in a hot and humid environment. This phenomenon is particularly prominent when preparing a condensation-type silicone pressure-sensitive adhesive, because in the condensation reaction, in order to ensure that the terminal hydroxyl polysiloxane and the MQ resin react fully, the hydroxyl content in the raw material needs to be increased to the maximum extent, and the presence of residual hydroxyl groups exacerbates the side reactions in a high temperature and high humidity environment. Therefore, the present invention can remove the residual hydroxyl groups in the system by adding a capping agent after neutralization to carry out a secondary capping reaction, which unexpectedly improves the heat and humidity resistance of the silicone pressure-sensitive adhesive.

[0012] As a preferred range of the present invention, in step 1), the mass ratio of the terminal hydroxyl polysiloxane to the MQ resin is 1:(0.5-2).

[0013] As a preferred range of the present invention, the viscosity average molecular weight of the terminal hydroxyl polysiloxane is 300,000-900,000, and the volatile matter is ≤5%, preferably, the volatile matter is ≤1%.

[0014] Preferably, the dissolution conditions of the terminal hydroxyl polysiloxane in the diluent are, for example, stirring and mixing at 30-120° C. for 0.5-24 h.

[0015] As the preferred range of the present invention, the weight average molecular weight of the MQ resin is 2500-25000, preferably 3000-8000, and the hydroxyl content is 0.55%wt; preferably, the viscosity range of the 60% xylene solution of the MQ resin is 5-25mm 2 / s.

[0016] Preferably, after the MQ resin and the hydroxy-terminated polysiloxane are mixed, they are stirred at 30-120° C. for 0.5-24 h.

[0017] As a preferred scope of the present invention, in step 2), the catalyst is an organic base and / or an inorganic base catalyst, preferably one or more of lithium methoxide, sodium methoxide, n-butyl lithium, potassium hydroxide, sodium hydroxide, magnesium hydroxide, tetramethylammonium hydroxide, and ammonia water;

[0018] Preferably, the amount of the catalyst is 0.001-1% by mass of the hydroxy-terminated polysiloxane, preferably 0.005-0.1%;

[0019] As a preferred scope of the present invention, in step 3), the neutralizing agent is selected from organic acids, preferably one or more of phosphoric acid, acetic acid, tri(trimethylsilyl)phosphine, oxalic acid, metasilicic acid, carbonic acid, and hypochlorous acid;

[0020] Preferably, the amount of the neutralizing agent is 0.01-10% of the mass of the hydroxy-terminated polysiloxane, preferably 0.01-1%;

[0021] Preferably, the stirring and mixing time after adding the neutralizing agent in step 3) is, for example, 0.5-5 h.

[0022] As a preferred scope of the present invention, in step 3), the rare earth stabilizer is one or more of cerium chloride, lanthanum chloride, lanthanum carbonate, cerium carbonate, cerium isooctanoate, cerium neodecanoate, cerium oxide, yttrium oxide, and cerium sulfate;

[0023] Preferably, the amount of the rare earth stabilizer is 0.01-10% of the mass of the hydroxy-terminated polysiloxane, preferably 0.01-1%;

[0024] Preferably, in step 3), the stirring and mixing time after adding the rare earth stabilizer is, for example, 0.5-5 h.

[0025] As a preferred scope of the present invention, in step 4), the end-capping agent is one or more of hexamethyldisiloxane, dimethylchlorosilane, trimethylchlorosilane, tetramethyldivinyldisiloxane, tetramethyldisiloxane, methyltrimethoxysilane, dimethyldimethoxysilane, hexamethyldisilazane, methylvinyldimethoxysilane, and trimethylsilanol;

[0026] Preferably, the amount of the end-capping agent is 0.5-20% of the mass of the hydroxyl-terminated polysiloxane, preferably 5-15%;

[0027] As a preferred scope of the present invention, the diluent is one or more of benzene, toluene, xylene, n-heptane, n-hexane, tetrahydrofuran, hexamethyldisiloxane, tetramethyldivinyldisiloxane.

[0028] Preferably, the total amount of the diluent used may be 1-3 times the mass of the hydroxy-terminated polysiloxane.

[0029] As a preferred range of the present invention, step 4) reacts until the hydroxyl content in the system is less than 1wt%, and then cools and discharges;

[0030] Preferably, the reaction time in step 4) is, for example, 1-6 h.

[0031] The organic silicone pressure-sensitive adhesive prepared by the above method has a viscosity of 5000-200000 cP, a solid content of 30-80%, and an acid value of ≤0.05 mgKOH / g.

[0032] The pressure-sensitive adhesive prepared by the present invention has the application performance of no residual adhesive on the steel plate at 260-280°C after curing, and has good initial adhesion performance and long-lasting adhesion. At the same time, the pressure-sensitive adhesive tape prepared thereby still has excellent high temperature resistance after aging under high humidity and heat conditions. DETAILED DESCRIPTION

[0033] The present invention is further described below by means of specific examples. The examples described in the present invention are only used to illustrate the present invention and do not limit the scope of the present invention.

[0034] The main raw material information used in the following examples of the present invention is as follows:

[0035] 107 raw rubber-300,000: hydroxyl-terminated polysiloxane with a viscosity-average molecular weight of 300,000, volatile matter 1%, Shenzhen Jipeng Silicone Fluoride Materials Co., Ltd.;

[0036] 107 raw rubber-600,000: hydroxy-terminated polysiloxane with a viscosity-average molecular weight of 600,000, volatile matter 1%, Shenzhen Jipeng Silicone Fluoride Materials Co., Ltd.;

[0037] 107 raw rubber-900,000: hydroxyl-terminated polysiloxane with a viscosity-average molecular weight of 900,000, volatile matter 1.4%, Shenzhen Jipeng Silicone Fluoride Materials Co., Ltd.;

[0038] MQ resin-1: weight average molecular weight is 3899, hydroxyl content is 1.4wt%, 60% xylene solution viscosity is 7mm 2 / s; prepared according to the method disclosed in patent CN109553773B;

[0039] MQ resin-2: weight average molecular weight is 5700, hydroxyl content is 3.3wt%, 60% xylene solution viscosity is 16mm 2 / s;;Prepared with reference to the method disclosed in patent CN109553773B;

[0040] MQ resin-3: weight average molecular weight is 8143, hydroxyl content is 4.2wt%, 60% xylene solution viscosity is 23mm 2 / s;;Prepared with reference to the method disclosed in patent CN109553773B;

[0041] Hexamethyldisiloxane, Inokane, purity 98%;

[0042] n-Butyl lithium solution, 1.6 mmol / L, Aladdin;

[0043] Lithium methoxide solution, 2.2mmol / L, Aladdin;

[0044] Hexamethyldisiloxane, Zhejiang Runhe, purity>99%;

[0045] Tetramethyldivinyldisiloxane, Quzhou Jiancheng, purity>99%;

[0046] Trimethylsilanol, Inochem, purity >99%.

[0047] Unless otherwise specified, other raw materials and reagents can be purchased from commercial sources.

[0048] The main test methods involved in the following embodiments of the present invention are as follows:

[0049] (1) Reference standard for pressure-sensitive adhesive adhesion / viscosity / solid content: Q / 0600YPU;

[0050] (2) Reference standard for hydroxyl content of pressure-sensitive adhesive: GB / T 9725-2007;

[0051] (3) Reference standard for pressure-sensitive adhesive rolling ball initial adhesion test: GB / T 4852-2002;

[0052] (4) Heat resistance test method: stick the pressure-sensitive tape to the steel plate according to the Q / 0600YPU adhesion test method, place it in a 260°C forced air oven for 30 minutes, remove the tape immediately after taking it out, and observe the residual adhesive on the surface of the steel plate;

[0053] (5) Aging and heat resistance test method: According to the Q / 0600YPU adhesion test method, the pressure-sensitive tape was attached to the steel plate, placed in an oven at 85% humidity and 85°C for aging for 3 days, taken out and cooled, and then the residual adhesive on the steel plate at 260°C was tested.

[0054] [Example 1]

[0055] In a four-mouth glass reactor equipped with mechanical stirring, thermometer, spherical condenser, and nitrogen pipeline, 62.93g of xylene and 69.22g of 107 raw rubber-600,000 were added, nitrogen was replaced three times, nitrogen atmosphere was maintained, stirring was turned on, the speed was set to 300rpm, the temperature was set to 60°C, and stirring was performed for 2h to fully dissolve the terminal hydroxyl polysiloxane. MQ resin-1 was dissolved in xylene to prepare a solution with a solid content of 67.11%, 133.951g was added to the reactor, and stirring and mixing continued for 1h. Then 0.008g of pyridine was added, and the temperature was raised to 145°C and refluxed for 6h. Cooled to 30°C, 0.04g of acetic acid was added, stirred for 1h, and 4.45g of lanthanum chloride was added, and fully stirred and mixed for 0.5h. Finally, 3.4g of tetramethyl divinyl disiloxane was added to the system, and mixing continued at 60°C for 2h, and the temperature was lowered to discharge to obtain 263.33g of pressure-sensitive adhesive.

[0056] [Example 2]

[0057] Add 51.63g toluene and 113.41g 107 raw rubber-900,000 to a four-mouth glass reactor equipped with mechanical stirring, thermometer, spherical condenser, and nitrogen pipeline, replace nitrogen three times, maintain nitrogen atmosphere, turn on stirring, set the speed to 300rpm, set the temperature to 80℃, stir for 2h, and fully dissolve the terminal hydroxyl polysiloxane. Dissolve MQ resin-2 in toluene to prepare a solution with a solid content of 55.56%, take 165.96g and add it to the reactor, and continue to stir and mix for 1h. Add 0.3g lithium methoxide solution (2.2mmol / L), heat to 100℃ and reflux for 4h. Cool to 60℃, add 0.12g carbonic acid, stir for 1h, then add 2.77g cerium sulfate, and stir and mix thoroughly for 0.5h. Finally, 5.71 g of hexamethyldisiloxane was added to the system, and the mixture was mixed for 4 h at 100° C. The temperature was lowered and the material was discharged to obtain 323.462 g of a pressure-sensitive adhesive.

[0058] [Example 3]

[0059] In a four-mouth glass reactor equipped with mechanical stirring, thermometer, spherical condenser, and nitrogen pipeline, add 38.4g toluene and 72.90g 107 raw rubber-600,000, replace nitrogen three times, maintain nitrogen atmosphere, turn on stirring, set the speed to 300rpm, set the temperature to 70℃, stir for 2h, and fully dissolve the terminal hydroxyl polysiloxane. Dissolve MQ resin-3 in toluene to prepare a solution with a solid content of 52.91%, take 241.73g and add it to the reactor, and continue to stir and mix for 1h. Add 0.038g n-butyl lithium solution (1.6mmol / L), heat to 110℃ and reflux for 6h. Cool to 60℃, add 0.05g acetic acid, stir for 1h, then add 0.026g cerium sulfate, and stir and mix thoroughly for 0.5h. Finally, 5.22 g of hexamethyldisiloxane was added to the system, and mixing was continued at 70° C. for 4 h. The temperature was lowered and the material was discharged to obtain 338.29 g of a pressure-sensitive adhesive.

[0060] [Example 4]

[0061] In a four-mouth glass reactor equipped with mechanical stirring, thermometer, spherical condenser, and nitrogen pipeline, add 43.4g toluene and 95.48g 107 raw rubber-600,000, replace nitrogen three times, maintain nitrogen atmosphere, turn on stirring, set the speed to 300rpm, set the temperature to 60℃, stir for 2h, and fully dissolve the terminal hydroxyl polysiloxane. Dissolve MQ resin-1 in xylene to prepare a solution with a solid content of 71.43%, take 121.52g and add it to the reactor, and continue to stir and mix for 1h. Add 0.07g 9% sodium hydroxide solution, heat to 145℃ and reflux for 6h. Cool down to 40℃, add 1.74g phosphoric acid, stir for 1h, then add 0.05g lanthanum chloride, and stir and mix thoroughly for 0.5h. Finally, add 2.58g tetramethyl divinyl disiloxane to the system, continue mixing at 70℃ for 3h, cool down and discharge, and obtain 256.22g of pressure-sensitive adhesive.

[0062] [Example 5]

[0063] In a four-mouth glass reactor equipped with mechanical stirring, thermometer, spherical condenser, and nitrogen pipeline, 119.28g of n-heptane and 138.02g of 107 raw rubber-600,000 were added, nitrogen was replaced three times, nitrogen atmosphere was maintained, stirring was turned on, the speed was set to 300rpm, the temperature was set to 50°C, and stirring was performed for 2h to fully dissolve the terminal hydroxyl polysiloxane. MQ resin-2 was dissolved in n-heptane to prepare a solution with a solid content of 58.82%, 289.68g was added to the reactor, and stirring and mixing continued for 1h. 5.11g of pyridine was added, and the temperature was raised to 100°C and refluxed for 6h. Cooled to 40°C, 1.70g of acetic acid was added, and after stirring for 1h, 8.52g of lanthanum chloride was added and fully stirred and mixed for 0.5h. Finally, 15.47g of hexamethyldisiloxane was added to the system, and mixing continued for 4h at 120°C, and the temperature was lowered to discharge to obtain 554.45g of pressure-sensitive adhesive.

[0064] [Example 6]

[0065] In a four-mouth glass reactor equipped with mechanical stirring, thermometer, spherical condenser, and nitrogen pipeline, add 373.32g toluene and 503.98g 107 raw rubber-300,000, replace nitrogen three times, maintain nitrogen atmosphere, turn on stirring, set the speed to 300rpm, set the temperature to 70℃, stir for 2h, and fully dissolve the terminal hydroxyl polysiloxane. Dissolve MQ resin-3 in toluene to prepare a solution with a solid content of 47.62%, take 653.31g and add it to the reactor, and continue to stir and mix for 1h. Add 0.31g n-butyl lithium solution (1.6mmol / L), heat to 110℃ and reflux for 6h. Cool to 80℃, add 0.22g tris(trimethylsilyl)phosphine, stir for 1h, then add 21.78g cerium sulfate, and stir and mix thoroughly for 0.5h. Finally, 19.87 g of trimethylsilanol was added to the system, and the mixture was mixed at 100° C. for 2 h. The temperature was lowered and the material was discharged to obtain 1514.09 g of a pressure-sensitive adhesive.

[0066] [Comparative Example 1]

[0067] A pressure-sensitive adhesive was prepared in substantially the same manner as in Example 1, except that tetramethyldivinyldisiloxane was not added at the end to continue the reaction, to obtain 259 g of pressure-sensitive adhesive.

[0068] The product indicators of the pressure-sensitive adhesives prepared in the embodiments and comparative examples are as follows:

[0069] Table 1. Product index information

[0070] Viscosity / cP Solid content / wt% Hydroxyl content / wt% Example 1 46730 58.8 0.56 Example 2 67770 61.59 0.33 Example 3 42320 56.87 0.61 Example 4 73750 69.51 0.31 Example 5 20450 54.85 0.08 Example 6 19430 52.49 0.41 Comparative Example 1 43570 57.90 2.24

[0071] After adding 2.2% of benzoyl peroxide by weight to the pressure-sensitive adhesives prepared in the embodiments and comparative examples, the pressure-sensitive adhesives were coated on a polyimide substrate, cured at 70°C for 1 min to remove the solvent, and then cured at 180°C for 2 minutes to obtain a PI adhesive film with a dry adhesive film of 35 μm. The tapes were cut into tapes, and the application properties such as adhesion, initial adhesion, and heat resistance were tested. The results are shown in Table 2:

[0072] Table 2. Film performance test results

[0073]

[0074] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this field can make several improvements and supplements without departing from the method of the present invention. These improvements and supplements should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a moisture-heat resistant silicone pressure-sensitive adhesive, characterized in that: The following steps are involved: 1) Dissolve the hydroxyl-terminated polysiloxane and MQ resin in diluent respectively, and then mix the two evenly; 2) Add a catalyst to the reaction solution, raise the temperature to 40-200°C, and reflux for 2-24 hours; 3) After the reaction, the temperature is controlled to 25-90°C, a neutralizer is added, and the mixture is mixed evenly, and then a rare earth stabilizer is added and the mixture is mixed evenly; 4) Continue to add the end-capping agent and react at 60-180° C. to obtain the silicone pressure-sensitive adhesive.

2. The method for preparing the heat and moisture resistant silicone pressure-sensitive adhesive according to claim 1, characterized in that: In step 1), the mass ratio of the terminal hydroxyl polysiloxane to the MQ resin is 1:(0.5-2).

3. The method for preparing the heat and moisture resistant silicone pressure-sensitive adhesive according to claim 1 or 2, characterized in that: The viscosity average molecular weight of the terminal hydroxyl polysiloxane is 300,000-900,000, and the volatile matter is ≤5%.

4. The method for preparing the heat-and-humidity resistant silicone pressure-sensitive adhesive according to any one of claims 1 to 3, characterized in that: The weight average molecular weight of the MQ resin is 2500-25000, and the hydroxyl content is 0.5-5.0%wt.

5. The method for preparing the heat-and-humidity resistant silicone pressure-sensitive adhesive according to any one of claims 1 to 4, characterized in that: In step 2), the catalyst is an organic base and / or an inorganic base catalyst, preferably one or more of lithium methoxide, sodium methoxide, n-butyl lithium, potassium hydroxide, sodium hydroxide, magnesium hydroxide, tetramethylammonium hydroxide, and ammonia water; Preferably, the amount of the catalyst is 0.001-1% of the mass of the hydroxy-terminated polysiloxane, preferably between 0.005-0.1%.

6. The method for preparing the heat-and-humidity resistant organic silicone pressure-sensitive adhesive according to any one of claims 1 to 5, characterized in that: In step 3), the neutralizing agent is selected from an organic acid, preferably one or more of phosphoric acid, acetic acid, tri(trimethylsilyl)phosphine, oxalic acid, metasilicic acid, carbonic acid, and hypochlorous acid; Preferably, the amount of the neutralizer is 0.01-10% by mass of the hydroxy-terminated polysiloxane, preferably 0.01-1%.

7. The method for preparing the heat-and-humidity resistant silicone pressure-sensitive adhesive according to any one of claims 1 to 6, characterized in that: In step 3), the rare earth stabilizer is one or more of cerium chloride, lanthanum chloride, lanthanum carbonate, cerium carbonate, cerium isooctanoate, cerium neodecanoate, cerium oxide, yttrium oxide, and cerium sulfate; Preferably, the amount of the rare earth stabilizer is 0.01-10% of the mass of the hydroxy-terminated polysiloxane, preferably 0.01-1%.

8. The method for preparing the heat-and-humidity resistant organic silicone pressure-sensitive adhesive according to any one of claims 1 to 7, characterized in that: In step 4), the end-capping agent is one or more of hexamethyldisiloxane, dimethylchlorosilane, trimethylchlorosilane, tetramethyldivinyldisiloxane, tetramethyldisiloxane, methyltrimethoxysilane, dimethyldimethoxysilane, hexamethyldisilazane, methylvinyldimethoxysilane, and trimethylsilanol; Preferably, the amount of the end-capping agent is 0.5-20% of the mass of the hydroxyl-terminated polysiloxane, preferably 5-15%.

9. The method for preparing the heat-and-humidity resistant organic silicone pressure-sensitive adhesive according to any one of claims 1 to 8, characterized in that: The diluent is one or more of benzene, toluene, xylene, n-heptane, n-hexane, tetrahydrofuran, hexamethyldisiloxane, and tetramethyldivinyldisiloxane.

10. The method for preparing the heat and moisture resistant organic silicone pressure sensitive adhesive according to any one of claims 1 to 9, characterized in that: Step 4) reacting until the hydroxyl content in the system is less than 1wt%, then cooling and discharging.

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