A silicone rubber catalyst and its preparation method and application

Abstract

The present invention is applicable to the technical field of preparation of organic silicon materials, and provides a silicone rubber catalyst, a preparation method and an application. A preparation method of a silicone rubber catalyst comprises the following steps: (1) titanate or titanium tetrachloride and mercaptopropyltrialkoxysilane are mixed in a solvent, stirred and heated, and reacted at a certain temperature for a period of time; (2) after the reaction is completed, filtering to remove insoluble solids, and performing reduced pressure distillation on the filtrate to remove low-boiling substances, and discharging to obtain a product. The present invention also provides an application of a silicone rubber catalyst in room temperature vulcanized dealcohol-type silicone rubber and room temperature vulcanized deoxime-type silicone rubber. The silicone rubber catalyst prepared by the present invention has a good catalytic effect in condensation-type room temperature vulcanized silicone rubber, can significantly enhance the bonding performance between silicone rubber and various substrates, and has good compatibility with other components in silicone rubber.

Description

Technical Field

[0001] The invention is applicable to the technical field of preparation of organic silicon materials and provides a silicone rubber catalyst and a preparation method and application thereof. Background Art

[0002] Condensation-type room temperature vulcanized silicone rubber has excellent resistance to UV light, weathering, high temperature and high humidity. Compared with other types of sealants, its durability under harsh conditions is particularly outstanding, especially single-component room temperature curing silicone sealant. Since the silicon-oxygen bond of its main component is relatively stable, it has excellent aging resistance and is widely used in construction, automobiles, lighting, electronics and electrical fields.

[0003] Room temperature vulcanized silicone rubber, especially dealcoholized and deoxime silicone rubber, has a slow vulcanization speed and usually requires the addition of a catalyst to promote the vulcanization process. In the production process of room temperature vulcanized silicone rubber, organic titanium and organic tin are generally added as catalysts at the same time.

[0004] At the same time, because silicone rubber is a highly saturated non-polar rubber with very low molecular surface energy, the inertness of silicone rubber itself makes its adhesion to most substrates poor. Therefore, tackifiers need to be added during the production of silicone rubber adhesives to improve the adhesion between silicone rubber and the substrate.

[0005] When using tackifiers for silicone rubber, the compatibility of the tackifier itself with silicone rubber must be considered. Low compatibility will lead to extremely high viscosity of the rubber system, affecting the dispersion of the tackifier and filler in the system, and even affecting the strength of the rubber itself. Chinese invention patent CN201480077485.2 discloses an acrylate copolymer tackifier formed by polymerization of acrylate monomers and unsaturated monomers, which has a good tackifying effect and good bonding properties to a variety of substrates. However, acrylate tackifiers are not compatible with silicone rubber, which will increase the viscosity of silicone rubber and cause a certain degree of yellowing of silicone rubber, which is not conducive to promotion and use. Summary of the invention

[0006] The purpose of the present invention is to provide a silicone rubber catalyst and a preparation method and application thereof, which have the advantage of significant viscosity-increasing effect.

[0007] In order to achieve the above object, the present invention provides a silicone rubber catalyst, the catalyst structure is as follows:

[0008]

[0009] A method for preparing a silicone rubber catalyst comprises the following steps:

[0010] (1) Titanate or titanium tetrachloride and mercaptopropyltrialkoxysilane are mixed in a solvent, stirred and heated, and reacted for a period of time at a certain temperature;

[0011] (2) After the reaction is completed, filter to remove insoluble solids, distill the filtrate under reduced pressure to remove low-boiling substances, and obtain the product.

[0012] Furthermore, the mercaptopropyltrialkoxysilane is at least one of mercaptopropyltrimethoxysilane, mercaptopropyltriethoxysilane, and mercaptopropylmethyldimethoxysilane; and the titanate is at least one of tetraisopropyl titanate, n-butyl titanate, n-propyl titanate, and tetraethyl titanate.

[0013] Furthermore, the titanate is selected from one or both of tetraisopropyl titanate and n-butyl titanate; the mercaptopropyltrialkoxysilane is one or both of mercaptopropyltrimethoxysilane and mercaptopropyltriethoxysilane.

[0014] Furthermore, the solvent is selected from at least one of isopropanol, toluene, xylene, chloroform and triethylamine.

[0015] Furthermore, the mixing method described in step (1) can be at least one of unidirectional dripping, bidirectional dripping, and direct addition and mixing.

[0016] Furthermore, in step (1), the ratio of the amount of titanate or titanium tetrachloride, mercaptopropyltrialkoxysilane and solvent is 1:4:4-9.

[0017] Furthermore, in step (1), the reaction temperature is 75°C to 90°C, and the reaction time is 3h to 4h.

[0018] Furthermore, in step (2), the method of removing low boiling points by reduced pressure distillation is as follows: removing at a temperature of 75 to 90° C. and a vacuum of -0.07 to -0.09 MPa for 1.5 to 2 hours.

[0019] A silicone rubber catalyst is used in room temperature vulcanized dealcoholized silicone rubber and room temperature vulcanized deoxime silicone rubber.

[0020] The object of the present invention is to provide a silicone rubber catalyst and a preparation method and application thereof, which have the following beneficial effects:

[0021] ① The dealcoholization and deoxime room temperature vulcanized silicone rubber produced using this catalyst can not only achieve a good catalytic effect without adding an organic tin catalyst, but also effectively improve the cohesive failure rate of silicone rubber to metal substrates such as aluminum, copper and stainless steel and plastics such as PVC and ABS, and significantly improve the bonding ability.

[0022] ② The catalyst has good compatibility with other components in silicone rubber, such as organic silicon coupling agent, thus avoiding quality problems caused by compatibility.

[0023] ③ The catalyst prepared by the present invention has a simple preparation process, readily available raw materials, recyclable solvents, low equipment requirements, and is easy to realize industrial production. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. The materials, reagents, etc. used in the following embodiments, unless otherwise specified, can all be obtained from commercial sources.

[0025] Example 1

[0026] Preparation of silicone rubber catalyst:

[0027] Add 20g of tetraisopropyl titanate and 21.03g of isopropanol into a 100ml three-necked flask, heat it to 65°C under stirring, weigh 54.98g of mercaptopropyltrimethoxysilane, slowly add it dropwise into the three-necked flask using a dropping funnel, control the dropping speed, and complete the addition within 1h. Finally, heat it to 75°C, keep the temperature for reaction for 3h, and then remove low boiling points at 75°C and vacuum -0.07MPa for 1.5h to obtain silicone rubber catalyst 1.

[0028] Preparation of dealcoholized silicone rubber

[0029] 1000g of 107 silicone rubber with a viscosity of 20000mPa·s, 900g of active nano-calcium carbonate, and 100g of dimethyl silicone oil were added to a dispersing rubber making machine, heated to 120°C, and vacuumed and dehydrated for 60 minutes to obtain a premix. After cooling to room temperature, 48g of methyltrimethoxysilane and 5g of silane coupling agent KH-560 were added, stirred at low speed for 30 minutes under normal pressure, and then 12g of silicone rubber catalyst 1 was added, and the dealcoholized silicone rubber was obtained after vacuuming and high-speed stirring for 30 minutes.

[0030] Example 2

[0031] Preparation of silicone rubber catalyst:

[0032] Add 25.8g of toluene to a 100ml three-necked flask and heat it to 75°C under stirring. Weigh 20g of tetraisopropyl titanate and 66.76g of mercaptopropyltriethoxysilane and add them into two dropping funnels respectively. Slowly drop them into the three-necked flask at the same time, control the dropping speed, and complete the dropping within 1h. Finally, heat it to 90°C and keep it for 4h. Then, remove low boiling points at 90°C under vacuum -0.07MPa for 2h to obtain silicone rubber catalyst 2.

[0033] The method for preparing dealcoholized silicone rubber in this embodiment is consistent with that in Embodiment 1, except that 12 g of silicone rubber catalyst 1 is replaced by 12 g of silicone rubber catalyst 2.

[0034] Example 3

[0035] Preparation of silicone rubber catalyst:

[0036] Add 15g titanium tetrachloride and 36.4g toluene into a 100ml three-necked flask, heat to 60°C under stirring, weigh 32g triethylamine and 62.04g mercaptopropyltrimethoxysilane and add them into two dropping funnels respectively, slowly add them into the three-necked flask at the same time, control the dropping speed, and complete the dropping within 1h. Finally, heat to 75°C and keep the temperature for 4h. Filter under reduced pressure in a suction flask to filter out insoluble matter, and remove low-boiling substances from the obtained mother liquor at 75°C and vacuum at -0.09MPa for 1.5h to obtain silicone rubber catalyst 3.

[0037] The method for preparing dealcoholized silicone rubber in this embodiment is consistent with that in Embodiment 1, except that 12 g of silicone rubber catalyst 1 is replaced by 12 g of silicone rubber catalyst 3.

[0038] Example 4

[0039] Preparation of silicone rubber catalyst:

[0040] Add 20g of n-butyl titanate and 27.18g of toluene into a 100ml three-necked flask, heat it to 75°C under stirring, weigh 46.34g of mercaptopropyltrimethoxysilane, slowly add it dropwise into the three-necked flask using a dropping funnel, control the dropping speed, and complete the addition within 1h. Finally, heat it to 90°C, keep the temperature for reaction for 3h, then remove low boiling points at 90°C and vacuum -0.08MPa for 2h to obtain silicone rubber catalyst 4.

[0041] The method for preparing dealcoholized silicone rubber in this embodiment is consistent with that in Embodiment 1, except that 12 g of silicone rubber catalyst 1 is replaced by 12 g of silicone rubber catalyst 4.

[0042] Comparative Example 1

[0043] 1000g of 107 silicone rubber with a viscosity of 20000mPa·s, 900g of active nano-calcium carbonate, and 100g of dimethyl silicone oil were added to a dispersing rubber making machine, heated to 120°C, and vacuumed and dehydrated for 60 minutes to obtain a premix. After cooling to room temperature, 48g of methyltrimethoxysilane and 5g of silane coupling agent KH-560 were added, and stirred at low speed for 30 minutes under normal pressure, and then 12g of titanate chelate and 0.5g of dibutyltin dilaurate were added, and the dealcoholized silicone rubber was obtained after vacuuming and high-speed stirring for 30 minutes.

[0044] Comparative Example 2

[0045] Add 20g of isopropyl titanate and 21.03g of isopropanol into a 100ml three-necked flask, heat it to 65°C under stirring, weigh 54.98g of mercaptopropyltrimethoxysilane, slowly add it dropwise into the three-necked flask using a dropping funnel, control the dropping speed, and complete the addition within 1h. Finally, heat it to 75°C, keep the temperature for reaction for 3h, and then remove low-boiling substances at 75°C and vacuum -0.07MPa for 1.5h to obtain silicone rubber catalyst 1.

[0046] The method for preparing the dealcoholized silicone rubber in this comparative example is the same as that in Example 1, except that 5 g of silane coupling agent KH-560 is replaced by 7 g of silane coupling agent KH-550.

[0047] Comparative Example 3

[0048] 1000g of 107 silicone rubber with a viscosity of 20000mPa·s, 900g of active nano-calcium carbonate, and 100g of dimethyl silicone oil were added to a dispersing rubber making machine, heated to 120°C, and vacuumed and dehydrated for 60 minutes to obtain a premix. After cooling to room temperature, 48g of methyltrimethoxysilane and 5g of silane coupling agent KH-560 were added, and stirred at low speed for 30 minutes under normal pressure, and then 10g of titanate chelate and 0.8g of chelated tin catalyst were added, and the dealcoholized silicone rubber was obtained after vacuuming and high-speed stirring for 30 minutes.

[0049] Comparative Example 4

[0050] Add 20g of isopropyl titanate and 21.03g of isopropanol into a 100ml three-necked flask, heat it to 65°C under stirring, weigh 54.98g of mercaptopropyltrimethoxysilane, slowly add it dropwise into the three-necked flask using a dropping funnel, control the dropping speed, and complete the addition within 1h. Finally, heat it to 75°C, keep the temperature for reaction for 3h, and then remove low-boiling substances at 75°C and vacuum -0.07MPa for 1.5h to obtain silicone rubber catalyst 1.

[0051] The method for preparing the dealcoholized silicone rubber in this comparative example is the same as that in Example 1, except that 5 g of the silane coupling agent KH-560 is replaced by 6 g of the silane coupling agent KH-792.

[0052] The surface drying and detackifying properties of the silicone rubber of Examples 1-4 and Comparative Examples 1-4 after conventional (room temperature vulcanization) and aging (aging at 90°C for 3 days) were tested. (According to the GB16776-2005 test, under standard conditions, the surface drying time of a single-component silicone rubber is qualified within 3 hours and the detackifying time is within 24 hours.)

[0053] According to the test method specified in the national standard GB7124-1986, the silicone rubbers of Examples 1-4 and Comparative Examples 1-4 were coated on the surfaces of different substrates, including aluminum sheet, stainless steel sheet, glass, PVC plastic, and ABS plastic, to prepare samples, and their bonding shear strength was tested.

[0054] The performance comparison of the silicone rubber prepared in Examples 1-4 and Comparative Examples 1-4 is shown in the table below:

[0055]

[0056] It can be seen from the results of Examples 1-4 and Comparative Examples 1-4 that, in Examples 1-4, without adding an organic tin catalyst and without adding an additional tackifier, only the catalysts 1-4 prepared by the present invention are added, and the dealcoholized silicone rubber prepared can maintain good surface drying and detackifying properties both at room temperature and after aging, proving that the catalyst prepared by the present invention has a good catalytic effect.

[0057] At the same time, according to the method specified in GB7124-1986, the bonding shear strength of Examples 1-4 and Comparative Examples 1-4 on the surfaces of various different substrates was tested. The results show that when Comparative Examples 1 and 3 use the same coupling agent as Examples 1-4 but use other catalysts, the bonding shear strength of the silicone rubber obtained is significantly lower than that of Examples 1-4, proving that the catalyst prepared by the present invention has a significant viscosity-increasing effect.

[0058] Comparative Examples 2 and 4, like Example 1, all use the catalysts prepared by the present invention. However, when different coupling agents are used, the bonding shear strength of the prepared silicone rubber on the surfaces of various different substrates is still very high, and the bonding strength is basically close to that of Example 1, which proves that the catalysts prepared by the present invention have good compatibility with other coupling agents.

[0059] The catalyst prepared by the present invention is used to produce condensation-type room temperature vulcanized silicone rubber. Without the need to add an organic tin catalyst and without the need to add an additional tackifier, the prepared silicone rubber adhesive has a good vulcanization effect and can significantly increase the bonding shear strength between the silicone rubber and the substrate, thereby simplifying the production process, reducing production costs, and effectively improving the bonding performance of the silicone rubber.

[0060] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for preparing a silicone rubber catalyst, characterized in that: The catalyst structural formula is as follows: The preparation method of the catalyst comprises the following steps: (1) Titanate or titanium tetrachloride and mercaptopropyltrialkoxysilane are mixed in a solvent, stirred and heated, and reacted for a period of time at a certain temperature; (2) After the reaction is completed, filter to remove insoluble solids, distill the filtrate under reduced pressure to remove low-boiling substances, and obtain the product.

2. The method for preparing a silicone rubber catalyst according to claim 1, characterized in that: The mercaptopropyl trialkoxysilane is mercaptopropyl trimethoxysilane; the titanate is at least one of tetraisopropyl titanate, n-butyl titanate, n-propyl titanate, and tetraethyl titanate.

3. The method for preparing a silicone rubber catalyst according to claim 2, characterized in that: The titanate is selected from one or both of tetraisopropyl titanate and n-butyl titanate; the mercaptopropyl trialkoxy silane is mercaptopropyl trimethoxy silane.

4. The method for preparing a silicone rubber catalyst according to claim 1, characterized in that: The solvent is selected from at least one of isopropanol, toluene, xylene, chloroform and triethylamine.

5. The method for preparing a silicone rubber catalyst according to claim 1, characterized in that: The mixing method described in step (1) can specifically be at least one of unidirectional dripping, bidirectional dripping, and direct addition and mixing.

6. The method for preparing a silicone rubber catalyst according to claim 1, characterized in that: In step (1), the ratio of the amount of titanate or titanium tetrachloride, mercaptopropyltrialkoxysilane and solvent is 1:4:4-9.

7. The method for preparing a silicone rubber catalyst according to claim 1, characterized in that: In step (1), the reaction temperature is 75°C to 90°C, and the reaction time is 3h to 4h.

8. The method for preparing a silicone rubber catalyst according to claim 1, characterized in that: The method of removing low boiling points by reduced pressure distillation in step (2) is as follows: removing at a temperature of 75 to 90° C. and a vacuum of -0.07 to -0.09 MPa for 1.5 to 2 hours.

9. Use of the silicone rubber catalyst prepared by the method for preparing the silicone rubber catalyst as claimed in claim 1 in room temperature vulcanized dealcoholization type silicone rubber and room temperature vulcanized deoxime type silicone rubber.

Images