A method for preparing a fast-curing mixed silicone rubber

Abstract

The application discloses a preparation method of rapidly vulcanized mixed and kneaded silicone rubber and belongs to the technical field of silicone rubber preparation. The method comprises four steps of raw material pretreatment, basic kneading, vulcanization system kneading and vulcanization forming. Raw materials are proportioned according to specific weight parts, 4,4'-diamino diphenyl ether and 3,3'-dimethyl-4,4'-diamino dicyclohexyl methane are compounded as vulcanization accelerators, cooperate with platinum catalysts, and combined with step-by-step kneading process to realize rapid vulcanization of mixed and kneaded silicone rubber. The vulcanization time is shortened to 3-8 min, the vulcanization temperature is reduced to 120-140 DEG C, the vulcanization efficiency is increased by more than 60%, meanwhile, the hardness of the silicone rubber after vulcanization is 50-70 Shore A, the tensile strength is greater than or equal to 3.5 MPa, the elongation at break is greater than or equal to 300%, and the comprehensive performance is excellent. The preparation process is simple, raw materials are cheap and easy to obtain, and the cost is controllable. No special equipment is needed, and the method is easy to realize industrial large-scale production and is suitable for multiple fields such as electronics, automobiles and buildings.

Description

Technical Field

[0001] This invention relates to the field of silicone rubber preparation and related products, specifically a method for preparing rapidly vulcanized compounded silicone rubber. Background Technology

[0002] Compounded silicone rubber, with its excellent high-temperature resistance, aging resistance, weather resistance, and good insulation properties, is widely used in various fields such as electronics, automotive manufacturing, medical devices, and building sealing. With the continuous improvement of industrial production efficiency, higher requirements are placed on the vulcanization speed of compounded silicone rubber. Rapid vulcanization can effectively shorten the production cycle, reduce production costs, and improve production efficiency.

[0003] Currently, existing vulcanization processes for compounded silicone rubber generally suffer from long vulcanization times, typically requiring prolonged exposure to high temperatures to complete vulcanization. This not only results in high energy consumption but also limits the efficiency of continuous production. While some technologies accelerate vulcanization by increasing catalyst dosage, this often leads to decreased processing properties of the silicone rubber, scorching, and may also affect the mechanical properties and aging resistance of the vulcanized silicone rubber. Other technologies add special vulcanization accelerators, but these suffer from drawbacks such as poor compatibility between the accelerator and the system, high cost, or instability in the properties of the vulcanized products.

[0004] Therefore, developing a rapid vulcanization method for preparing silicone rubber that can significantly shorten vulcanization time and reduce vulcanization temperature while ensuring the processing performance, mechanical properties, and aging resistance of the compounded silicone rubber, and that is simple and cost-effective, has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing rapidly vulcanized compounded silicone rubber to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing rapidly vulcanized compounded silicone rubber, comprising the following steps:

[0007] 1) Raw material pretreatment: Preheat the raw methyl vinyl silicone rubber in a constant temperature environment of 60-80℃ for 20-30 minutes, and set aside; Dry the filler at a temperature of 110-130℃ for 1-2 hours, and cool it to room temperature before use; Mix the vulcanization accelerator with a small amount of methyl silicone oil and stir evenly to prepare a pre-dispersion, and set aside.

[0008] 2) Basic mixing: Add the pretreated methyl vinyl silicone rubber raw rubber to the internal mixer, adjust the temperature of the internal mixer to 70-90℃, the speed to 30-50 r / min, and mix for 5-8 minutes until the raw rubber softens; then add the pretreated filler and structure control agent in sequence, and continue mixing for 10-15 minutes to obtain the basic compound.

[0009] 3) Vulcanization system mixing: Transfer the basic compound obtained in step 2) to a two-roll mill, adjust the temperature of the two-roll mill to 50-60℃ and the speed to 20-30 r / min, add hydrogen-containing polysiloxane and inhibitor, and mix for 3-5 min until uniform; then add the pre-dispersed vulcanization accelerator and platinum catalyst, and continue mixing for 2-4 min. After uniform mixing, discharge the material to obtain the rapid vulcanization compounded silicone rubber.

[0010] 4) Vulcanization molding: Place the mixed silicone rubber compound obtained in step 3) into the mold and vulcanize it using a flat vulcanizing machine. The vulcanization temperature is 120-140℃, the vulcanization pressure is 10-15MPa, and the vulcanization time is 3-8min. After vulcanization, cool to room temperature and demold to obtain the fast vulcanized mixed silicone rubber product.

[0011] 2. The method for preparing rapidly vulcanized compounded silicone rubber according to claim 1, characterized in that the raw materials are proportioned as follows by weight: 100 parts of methyl vinyl silicone rubber raw rubber, 30-60 parts of filler, 5-15 parts of hydrogen-containing polysiloxane, 0.01-0.05 parts of platinum catalyst, 0.05-0.2 parts of inhibitor, 0.5-2 parts of vulcanization accelerator, 1-3 parts of structure control agent, and 1-2 parts of methyl silicone oil.

[0012] As a preferred embodiment of the present invention, the methyl vinyl silicone rubber raw rubber has a molecular weight of 500,000 to 1,000,000 and a vinyl content of 0.1% to 0.5% (mol). At least two vinyl groups in the molecular chain are directly connected to silicon atoms. The vinyl groups are located at the chain ends or side chains of the polysiloxane, or simultaneously at the chain ends and side chains.

[0013] As a preferred embodiment of the present invention, the filler is one or more of fumed silica, precipitated silica, and silica powder; wherein the specific surface area of ​​fumed silica is 200-300 m² / g, and the specific surface area of ​​precipitated silica is 100-200 m² / g.

[0014] As a preferred embodiment of the present invention, the hydrogen-containing polysiloxane is a polysiloxane in which at least two hydrogen atoms are directly connected to silicon atoms in the molecular chain. The hydrogen atoms are located at the chain end or side chain of the polysiloxane, or simultaneously at the chain end and side chain. The mass of the hydrogen atoms accounts for 0.3%-1.2% of the hydrogen-containing polysiloxane. The hydrogen-containing polysiloxane is one or more of the following: linear, dendritic, and cyclic.

[0015] As a preferred embodiment of the present invention, the platinum catalyst is one or more of isopropanol chloroplatinate solution and divinyltetramethyldisiloxane complex of chloroplatinate, and the concentration of platinum atoms in the platinum catalyst is 1000-5000 ppm.

[0016] As a preferred embodiment of the present invention, the inhibitor is one or more of 1-ethynylcyclohexanol, 3,5-dimethyl-1-hexyn-3-ol, and tetramethyldivinyldisiloxane.

[0017] As a preferred embodiment of the present invention, the vulcanization accelerator is a compound of 4,4'-diaminodiphenyl ether and 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, with a weight ratio of 1:0.5-2.

[0018] As a preferred embodiment of the present invention, the structure control agent is one or both of hexamethyldisilazane and tetramethyldivinylsilazane.

[0019] As a preferred embodiment of the present invention, in step 3), during the mixing process on the open mill, the thickness of the rubber compound needs to be controlled to be 2-5mm, and the compound is repeatedly turned over 3-4 times to ensure that each component is evenly dispersed.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] This invention optimizes the raw material ratio by using a compound of 4,4'-diaminodiphenyl ether and 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane as a vulcanization accelerator. In synergy with a platinum catalyst, it can significantly accelerate the vulcanization reaction rate and shorten the vulcanization time to 3-8 minutes, compared with the 15-30 minutes of the prior art, the vulcanization efficiency is increased by more than 60%. At the same time, the vulcanization temperature is reduced to 120-140℃, effectively reducing energy consumption and improving production efficiency.

[0022] This invention pre-treats the raw materials and prepares the vulcanization accelerator into a pre-dispersion, which effectively solves the problems of poor compatibility and uneven dispersion between the accelerator and the rubber compound system. At the same time, through a step-by-step mixing process, the basic components are mixed first, and then the vulcanization system components are added to ensure that each component is evenly dispersed, avoid scorching, and ensure excellent processing performance of the rubber compound. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0024] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," indicating orientation or positional relationships, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0025] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0026] Example 1

[0027] A method for preparing rapidly vulcanized compounded silicone rubber includes the following steps:

[0028] 1) Raw material pretreatment: 100 parts by weight of methyl vinyl silicone rubber raw rubber (molecular weight 700,000, vinyl content 0.3% (mol)) was preheated at 70℃ for 25 min and set aside; 30 parts by weight of fumed silica (specific surface area 250 m² / g) was dried at 120℃ for 1.5 h and cooled to room temperature and set aside; 0.5 parts by weight of vulcanization accelerator (4,4'-diaminodiphenyl ether and 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane in a weight ratio of 1:1) was mixed with 1 part by weight of methyl silicone oil and stirred evenly to prepare a pre-dispersion and set aside.

[0029] 2) Basic mixing: Add the pretreated methyl vinyl silicone rubber raw rubber to the internal mixer, adjust the temperature of the internal mixer to 80℃ and the speed to 40r / min, and mix for 6min until the raw rubber softens; then add the pretreated fumed silica and 1 part by weight of hexamethyldisilazane in sequence, and continue mixing for 12min to obtain the basic compound.

[0030] 3) Vulcanization system mixing: Transfer the basic compound obtained in step 2) to a two-roll mill, adjust the temperature of the two-roll mill to 55℃ and the speed to 25r / min, add 5 parts by weight of hydrogen-containing polysiloxane (hydrogen atomic mass percentage 0.7%, linear) and 0.05 parts by weight of 1-ethynylcyclohexanol, and mix for 4 minutes until uniform; then add the pre-dispersed vulcanization accelerator and 0.01 parts by weight of isopropanol chloroplatinic acid solution (platinum atomic concentration 3000ppm), continue mixing for 3 minutes, control the thickness of the rubber compound to 3mm, repeat the mixing process 3 times, and discharge the material after uniform mixing to obtain the rapid vulcanization compounded silicone rubber compound;

[0031] 4) Vulcanization molding: Place the mixed silicone rubber compound obtained in step 3) into the mold and vulcanize it using a flat vulcanizing machine. The vulcanization temperature is 130℃, the vulcanization pressure is 12MPa, and the vulcanization time is 5min. After vulcanization, cool to room temperature and demold to obtain the fast vulcanized mixed silicone rubber product.

[0032] Testing showed that the rapid vulcanization compounded silicone rubber product prepared in this embodiment has a hardness of 60 Shore A, a tensile strength of 4.2 MPa, an elongation at break of 350%, a vulcanization time that is 67% shorter than that of the prior art, and a 30% reduction in energy consumption.

[0033] Example 2

[0034] A method for preparing rapidly vulcanized compounded silicone rubber includes the following steps:

[0035] 1) Raw material pretreatment: 100 parts by weight of methyl vinyl silicone rubber raw rubber (molecular weight 500,000, vinyl content 0.1% (mol)) was preheated in a constant temperature environment of 60℃ for 30 min and set aside; 45 parts by weight of precipitated silica (specific surface area 150 m² / g) was dried at 110℃ for 2 h and cooled to room temperature and set aside; 1.2 parts by weight of vulcanization accelerator (4,4'-diaminodiphenyl ether and 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane in a weight ratio of 1:0.5) was mixed with 1.5 parts by weight of methyl silicone oil and stirred evenly to prepare a pre-dispersion and set aside.

[0036] 2) Basic mixing: Add the pretreated methyl vinyl silicone rubber raw rubber to the internal mixer, adjust the temperature of the internal mixer to 70℃ and the speed to 30r / min, and mix for 8min until the raw rubber softens; then add the pretreated precipitated silica and 2 parts by weight of tetramethyldivinylsilazane in sequence, and continue mixing for 15min to obtain the basic compound.

[0037] 3) Vulcanization system mixing: Transfer the basic compound obtained in step 2) to a two-roll mill, adjust the temperature of the two-roll mill to 50℃ and the speed to 20r / min, add 10 parts by weight of hydrogen-containing polysiloxane (0.3% hydrogen atomic mass, dendritic) and 0.1 parts by weight of 3,5-dimethyl-1-hexyn-3-ol, and mix for 5 minutes until uniform; then add the pre-dispersed vulcanization accelerator and 0.03 parts by weight of chloroplatinic acid-divinyltetramethyldisiloxane complex (platinum atomic concentration 1000ppm), and continue to mix for 4 minutes, controlling the thickness of the rubber compound to 2mm, and repeat the mixing process 4 times. After uniform mixing, discharge the material to obtain the rapid vulcanization compounded silicone rubber.

[0038] 4) Vulcanization molding: Place the mixed silicone rubber compound obtained in step 3) into the mold and vulcanize it using a flat vulcanizing machine. The vulcanization temperature is 120℃, the vulcanization pressure is 10MPa, and the vulcanization time is 8min. After vulcanization, cool to room temperature and demold to obtain the fast vulcanized mixed silicone rubber product.

[0039] Testing showed that the rapid vulcanization compounded silicone rubber product prepared in this embodiment has a hardness of 50 Shore A, a tensile strength of 3.5 MPa, an elongation at break of 300%, a vulcanization time that is 60% shorter than that of the prior art, and a 25% reduction in energy consumption.

[0040] Example 3

[0041] A method for preparing rapidly vulcanized compounded silicone rubber includes the following steps:

[0042] 1) Raw material pretreatment: 100 parts by weight of methyl vinyl silicone rubber raw rubber (molecular weight 1 million, vinyl content 0.5% (mol)) was preheated in a constant temperature environment of 80℃ for 20 min and set aside; 60 parts by weight of a mixture of silica powder and fumed silica (weight ratio 1:1, specific surface area of ​​fumed silica 300 m² / g) was dried at 130℃ for 1 h and cooled to room temperature and set aside; 2 parts by weight of vulcanization accelerator (4,4'-diaminodiphenyl ether and 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane in a weight ratio of 1:2) were mixed with 2 parts by weight of methyl silicone oil and stirred evenly to prepare a predispersant and set aside.

[0043] 2) Basic mixing: Add the pretreated methyl vinyl silicone rubber raw rubber to the internal mixer, adjust the temperature of the internal mixer to 90℃ and the speed to 50r / min, and mix for 5min until the raw rubber softens; then add the pretreated mixed filler and 3 parts by weight of the mixture of hexamethyldisilazane and tetramethyldisilazane (weight ratio 1:1) in sequence, and continue mixing for 10min to obtain the basic compound;

[0044] 3) Vulcanization system mixing: Transfer the basic compound obtained in step 2) to a two-roll mill, adjust the temperature of the two-roll mill to 60℃ and the speed to 30r / min, add 15 parts by weight of hydrogen-containing polysiloxane (hydrogen atomic mass percentage of 1.2%, cyclic) and 0.2 parts by weight of tetramethyldivinyldisiloxane, and mix for 3 minutes until uniform; then add the pre-dispersed vulcanization accelerator and 0.05 parts by weight of isopropanol chloroplatinate solution (platinum atomic concentration of 5000ppm), continue mixing for 2 minutes, control the thickness of the rubber compound to 5mm, repeat the mixing process 3 times, and discharge the material after uniform mixing to obtain the rapid vulcanization compounded silicone rubber compound;

[0045] 4) Vulcanization molding: Place the mixed silicone rubber compound obtained in step 3) into the mold and vulcanize it using a flat vulcanizing machine. The vulcanization temperature is 140℃, the vulcanization pressure is 15MPa, and the vulcanization time is 3min. After vulcanization, cool to room temperature and demold to obtain the fast vulcanized mixed silicone rubber product.

[0046] Testing showed that the rapid vulcanization compounded silicone rubber product prepared in this embodiment has a hardness of 70 Shore A, a tensile strength of 4.8 MPa, an elongation at break of 380%, a vulcanization time that is 80% shorter than that of the prior art, and a 35% reduction in energy consumption.

[0047] Comparative Example: Using existing conventional preparation methods, without adding the vulcanization accelerator compound of the present invention, the remaining raw materials and dosages are the same as in Example 1. The vulcanization temperature is 150℃ and the vulcanization time is 20min. After testing, the finished product has a hardness of 58 Shore A, a tensile strength of 3.3MPa, and an elongation at break of 280%.

[0048] The comparison between Examples 1-3 and the comparative examples shows that the preparation method of the present invention can significantly shorten the vulcanization time and reduce the vulcanization temperature while ensuring or even improving the comprehensive mechanical properties of the compounded silicone rubber, thus solving the problem that vulcanization efficiency and product performance are difficult to balance in the prior art.

[0049] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for preparing rapidly vulcanized compounded silicone rubber, characterized in that: Includes the following steps: 1) Raw material pretreatment: Preheat the raw methyl vinyl silicone rubber in a constant temperature environment of 60-80℃ for 20-30 minutes, and set aside; Dry the filler at a temperature of 110-130℃ for 1-2 hours, and cool it to room temperature before use; Mix the vulcanization accelerator with a small amount of methyl silicone oil and stir evenly to prepare a pre-dispersion, and set aside. 2) Basic mixing: Add the pretreated methyl vinyl silicone rubber raw rubber to the internal mixer, adjust the temperature of the internal mixer to 70-90℃, the speed to 30-50 r / min, and mix for 5-8 minutes until the raw rubber softens; then add the pretreated filler and structure control agent in sequence, and continue mixing for 10-15 minutes to obtain the basic compound. 3) Vulcanization system mixing: Transfer the basic compound obtained in step 2) to a two-roll mill, adjust the temperature of the two-roll mill to 50-60℃ and the speed to 20-30 r / min, add hydrogen-containing polysiloxane and inhibitor, and mix for 3-5 min until uniform; then add the pre-dispersed vulcanization accelerator and platinum catalyst, and continue mixing for 2-4 min. After uniform mixing, discharge the material to obtain the rapid vulcanization compounded silicone rubber. 4) Vulcanization molding: Place the mixed silicone rubber compound obtained in step 3) into the mold and vulcanize it using a flat vulcanizing machine. The vulcanization temperature is 120-140℃, the vulcanization pressure is 10-15MPa, and the vulcanization time is 3-8min. After vulcanization, cool to room temperature and demold to obtain the fast vulcanized mixed silicone rubber product.

2. The method for preparing rapidly vulcanized compounded silicone rubber according to claim 1, characterized in that, The raw materials are formulated in the following proportions by weight: 100 parts of methyl vinyl silicone rubber raw rubber, 30-60 parts of filler, 5-15 parts of hydrogen-containing polysiloxane, 0.01-0.05 parts of platinum catalyst, 0.05-0.2 parts of inhibitor, 0.5-2 parts of vulcanization accelerator, 1-3 parts of structure control agent, and 1-2 parts of methyl silicone oil.

3. The method for preparing rapidly vulcanized compounded silicone rubber according to claim 1 or 2, characterized in that, The methyl vinyl silicone rubber raw rubber has a molecular weight of 500,000 to 1,000,000 and a vinyl content of 0.1% to 0.5% (mol). At least two vinyl atoms in the molecular chain are directly connected to silicon atoms. The vinyl atoms are located at the chain end or side chain of the polysiloxane, or simultaneously at the chain end and side chain.

4. The method for preparing rapidly vulcanized compounded silicone rubber according to claim 1 or 2, characterized in that, The filler is one or more of fumed silica, precipitated silica, and silica powder; wherein the specific surface area of ​​fumed silica is 200-300 m² / g, and the specific surface area of ​​precipitated silica is 100-200 m² / g.

5. The method for preparing rapidly vulcanized compounded silicone rubber according to claim 1 or 2, characterized in that, The hydrogen-containing polysiloxane is a polysiloxane in which at least two hydrogen atoms are directly connected to silicon atoms in the molecular chain. The hydrogen atoms are located at the chain end or side chain of the polysiloxane, or at both the chain end and side chain. The mass of the hydrogen atoms accounts for 0.3%-1.2% of the hydrogen-containing polysiloxane. The hydrogen-containing polysiloxane is one or more of the following: linear, dendritic, and cyclic.

6. The method for preparing rapidly vulcanized compounded silicone rubber according to claim 1 or 2, characterized in that, The platinum catalyst is one or more of isopropanol chloroplatinate solution and divinyltetramethyldisiloxane complex, and the concentration of platinum atoms in the platinum catalyst is 1000-5000 ppm.

7. The method for preparing rapidly vulcanized compounded silicone rubber according to claim 1 or 2, characterized in that, The inhibitor is one or more of 1-ethynylcyclohexanol, 3,5-dimethyl-1-hexyn-3-ol, and tetramethyldivinyldisiloxane.

8. The method for preparing rapidly vulcanized compounded silicone rubber according to claim 1 or 2, characterized in that, The vulcanization accelerator is a compound of 4,4'-diaminodiphenyl ether and 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, with a weight ratio of 1:0.5-2.

9. The method for preparing rapidly vulcanized compounded silicone rubber according to claim 1 or 2, characterized in that, The structure control agent is one or both of hexamethyldisilazane and tetramethyldivinylsilazane.

10. The method for preparing rapidly vulcanized compounded silicone rubber according to claim 1, characterized in that, In step 3), during the mixing process on the open mill, the thickness of the rubber compound needs to be controlled at 2-5mm, and it needs to be repeatedly turned over 3-4 times to ensure that each component is evenly dispersed.