Two-component silicone pouring sealant and preparation method thereof

Abstract

The invention discloses a bi-component silicone pouring sealant and a preparation method thereof, the bi-component silicone pouring sealant is obtained by mixing bi-component preparation raw materials, the silicone pouring sealant comprises a compound with a structure as shown in a formula I, and the bi-component preparation raw materials comprise isocyanate modified silicone oil and hydroxyl modified silicone oil. According to the invention, basic silicone oil is modified, a large amount of isocyanate groups are introduced into the component A by using hydroxyl silicone oil, a specific hydroxyl structure is introduced into the component B by using carboxyl silicone oil, and the isocyanate groups in the two components react with hydroxyl to generate carbamate groups with extremely high bonding strength during mixing; and the adhesive property of the cured silicone pouring sealant is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of pouring sealant, and particularly relates to a two-component silicone pouring sealant and a preparation method thereof. BACKGROUND

[0002] The silicone pouring sealant is a high-molecular encapsulating material with polydimethylsiloxane as a matrix, and is widely used in the encapsulation of automobile electronics, power modules and aerospace fields. When the silicone pouring sealant is used for electronic and electrical pouring, the adhesion of the silicone pouring sealant itself is poor, and the device is prone to failure after pouring and curing.

[0003] To solve the problem, a primer can be applied to the device to be poured, and then pouring is performed after the primer is cured, but this method obviously increases the process, prolongs the processing time and increases the cost. The adhesion of the pouring sealant can be enhanced by adding an adhesion promoter (such as KH560, KH570, etc.) in the pouring sealant, and the adhesion of the pouring sealant after curing is enhanced by chemical or physical action of the adhesion promoter on the substrate. However, this method has problems such as instability of the pouring sealant and limited adhesion effect. SUMMARY

[0004] The application aims to provide a two-component silicone pouring sealant and a preparation method thereof, so as to solve at least one aspect of the problems and defects in the background.

[0005] To achieve the above-mentioned purpose, the application provides the following technical scheme.

[0006] A two-component silicone pouring sealant is prepared by mixing two-component raw materials, and the silicone pouring sealant comprises a compound with a structure shown in Formula I: ; R1 has a structure shown in Formula I-1: ; R3 and R4 are each independently selected from the following (a1) to (a5) divalent groups: (a1) one of 1,2-phenylene, 1,3-phenylene and 1,4-phenylene; (a2) C1-C12 linear or branched alkylene; (a3) C3-C10 cycloalkylene; (a4) has a structure shown in Formula a-4, wherein R9 is C1-C12 linear or branched alkylene: ; (a5) has a structure shown in Formula a-5, wherein R 10 is C1-C12 linear or branched alkylene: ; The R2 has the structure shown in Equation I-2: ; R5, R6, R7, and R8 are each independently selected from one of the following: C1-C8 straight-chain or branched alkylene groups, or hydroxy C1-C8 straight-chain or branched alkylene groups containing 1-4 hydroxyl groups. Wherein, 0≤n1≤500, 0≤n2≤500.

[0007] In this invention, Indicates the chemical bond connection site.

[0008] As a further embodiment of the present invention: R3 and R4 are each independently selected from any of the following structures: –(–CH2–CH2–CH2–CH2–CH2–CH2–)–, , , , , , , , .

[0009] As a further embodiment of the present invention: the two-component preparation raw materials include isocyanate-modified silicone oil and hydroxyl-modified silicone oil.

[0010] As a further embodiment of the present invention: the isocyanate-modified silicone oil has the structure shown in Formula I-1-1: .

[0011] As a further embodiment of the present invention: the hydroxyl-modified silicone oil has the structure shown in Formula I-2-1: .

[0012] As a further embodiment of the present invention: the isocyanate-modified silicone oil has the structure shown in Formula I-1-2: .

[0013] As a further embodiment of the present invention: the hydroxyl-modified silicone oil has the structure shown in Formula I-2-2: .

[0014] As a further embodiment of the present invention: 5≤n1≤200, 5≤n2≤200.

[0015] A method for preparing a two-component silicone potting compound includes the following steps: S1, hydroxyl silicone oil and isocyanate react to obtain component A, wherein the hydroxyl silicone oil has the structure shown in Formula I-1-3, where 5 ≤ n1 ≤ 200: ; S2, carboxyl silicone oil, and polyol react to obtain component B, wherein the carboxyl silicone oil has the structure shown in formula I-2-3, where 5 ≤ n2 ≤ 200: ; S3. Mix component A and component B to obtain the silicone potting compound.

[0016] As a further embodiment of the present invention: step S1 includes the following reaction: .

[0017] As a further embodiment of the present invention: step S2 includes the following reaction: .

[0018] As a further embodiment of the present invention: the isocyanate in step S1 is selected from at least one of MDI, HDI, TDI, and HMDI, preferably MDI.

[0019] The MDI mentioned in this invention refers to diphenylmethane diisocyanate.

[0020] The HDI mentioned in this invention refers to hexamethylene diisocyanate.

[0021] The TDI mentioned in this invention refers to toluene diisocyanate, including at least one of toluene-2,3-diisocyanate, toluene-2,4-diisocyanate, toluene-2,5-diisocyanate, toluene-2,6-diisocyanate, toluene-3,4-diisocyanate, and toluene-3,5-diisocyanate.

[0022] The HMDI mentioned in this invention refers to dicyclohexylmethane diisocyanate.

[0023] As a further embodiment of the present invention: the polyol mentioned in step S2 is selected from at least one of glycerol, pentaerythritol, trimethylolethane, xylitol, and sorbitol, preferably glycerol.

[0024] As a further embodiment of the present invention: the mass ratio of hydroxyl silicone oil and isocyanate in step S1 is (9~11):1, preferably (9.5~10.5):1.

[0025] As a further embodiment of the present invention: the mass ratio of carboxylated silicone oil and polyol in step S2 is (30~45):1, preferably (35~40):1.

[0026] As a further embodiment of the present invention: the mass ratio of component A to component B in step S3 is 1:(0.4~3), preferably 1:(0.8~2), and even more preferably 1:(1.3~1.5).

[0027] As a further embodiment of the present invention, the reaction temperature in step S1 is 80~150℃.

[0028] As a further embodiment of the present invention: the reaction stirring speed in step S1 is 300~700 rpm.

[0029] As a further embodiment of the present invention: the reaction in step S1 is carried out under vacuum, preferably with a vacuum gauge pressure ≤ -0.08 MPa.

[0030] As a further embodiment of the present invention, the reaction time in step S1 is 2 to 8 hours.

[0031] As a further embodiment of the present invention: the reaction temperature in step S2 is 30~150℃, preferably 105~150℃.

[0032] As a further embodiment of the present invention: the reaction stirring speed in step S2 is 200~600 rpm.

[0033] As a further embodiment of the present invention: the reaction in step S2 is carried out under vacuum, preferably with a vacuum gauge pressure ≤ -0.08 MPa.

[0034] As a further embodiment of the present invention, the reaction time in step S2 is 12 to 24 hours.

[0035] As a further embodiment of the present invention, the preparation method includes the following steps: Synthesis of S1 and A components S1-1: The hydroxyl silicone oil is stirred under vacuum at a temperature of 100~105℃ and 300~700rpm for 1~4 hours. After stirring is completed, stirring is stopped, heating is carried out, dry nitrogen is passed through, and the mixture is cooled to 60℃. S1-2: Add isocyanate, and stir under vacuum at 80~120℃ and 300~700rpm for 2~8 hours. After stirring is complete, stop stirring, heat, purge with dry nitrogen, and cool to 30℃. S1-3: Take out the reaction product from step S1-2, purify it with triethanolamine and cyclohexane to obtain component A; Synthesis of S2 and B components S2-1: Carboxylated silicone oil and dilute sulfuric acid are stirred under vacuum at a temperature of 30~60℃ and 200~600rpm for 0.5~2 hours; S2-2: Add polyol and stir under vacuum at 105~150℃ and 200~500rpm for 12~24 hours. After stirring is complete, stop stirring, heat, and cool to 30℃. S2-3: Take out the reaction product from step S2-2, purify it with ethanol, and obtain component B; S3. Preparation of silicone potting compound Mix component A and component B at a mass ratio of 1:(0.4~3) to obtain the silicone potting compound.

[0036] The present invention has at least the following technical effects: 1. Modify the base silicone oil by introducing a large number of isocyanate groups into component A using hydroxyl silicone oil and introducing specific hydroxyl structures into component B using carboxyl silicone oil. When mixed, the isocyanate groups in the two components react with the hydroxyl groups to generate urethane groups with extremely high adhesive strength, thereby improving the adhesive performance of the silicone potting compound after curing. 2. By reasonably adjusting the mixing ratio of component A and component B, the degree of cross-linking reaction can be controlled, so that the proportion of the spatial cage structure after cross-linking reaches the optimal level, significantly enhancing the adhesive performance of the silicone potting compound. Attached Figure Description

[0037] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0038] Figure 1 This is a schematic diagram illustrating the active groups of components A and B in an embodiment of the present invention; Figure 2 This is a schematic diagram of the core typical structure of the reaction products of components A and B in an embodiment of the present invention. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments.

[0040] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0041] In the following embodiments: The chemical structural formula of hydroxyl silicone oil is shown below, where n = 80~100: ; The chemical structural formula of carboxyl silicone oil is shown below, where n = 25~30: ; The number of portions indicates the number of weight portions.

[0042] Example 1 A two-component silicone potting compound, obtained by mixing component A and component B, is prepared by the following steps: Synthesis of S1 and A components S1-1: Add 2000 parts of hydroxyl silicone oil to a 5L high-speed disperser, set the temperature to 105℃, and vacuum stir at 500rpm for 1 hour. After stirring is complete, stop stirring, heat, purge with dry nitrogen, and cool to 60℃. S1-2: Add 200 parts of MDI (manufacturer: Wanhua Chemical Group Co., Ltd.) to the above high-speed disperser, set the temperature to 100℃, and vacuum stir at 500rpm for 4 hours. After stirring is completed, stop stirring, heat, purge with dry nitrogen, and cool to 30℃. S1-3: Take out the reaction product from step S1-2, add 50 parts of triethanolamine and stir to homogenize, then centrifuge to remove the supernatant; take out the lower layer reaction product, add 200 parts of cyclohexane and stir to homogenize, then centrifuge to remove the supernatant; take out the lower layer reaction product, add 200 parts of cyclohexane and stir to homogenize, then centrifuge to remove the supernatant. S1-4: Take out the lower reaction product from step S1-3 and perform low-temperature vacuum de-devouring treatment using a clean rotary evaporator for 2 hours to obtain component A; Synthesis of S2 and B components S2-1: Take 2000 parts of carboxylated silicone oil and 1 part of dilute sulfuric acid (mass fraction of 30%) and add them to a 5L reactor. Set the temperature to 40℃ and stir at 200rpm for 1 hour. S2-2: After stirring, add 50 parts of glycerol (manufacturer: Nanjing Changjiang Jiangyu Oil Co., Ltd.) to the above reaction vessel. Set the temperature to 125℃ and stir under vacuum at 200rpm for 12 hours. After stirring, stop stirring, heat, and cool to 30℃. S2-3: Take out the reaction product from step S2-2, add 100 parts of anhydrous ethanol and stir to homogenize, then centrifuge to remove the supernatant; take out the lower layer reaction product, add another 100 parts of anhydrous ethanol and stir to homogenize, then centrifuge to remove the supernatant; take out the lower layer reaction product, add another 100 parts of anhydrous ethanol and stir to homogenize, then centrifuge to remove the supernatant. S2-4: Remove the lower reaction product and perform low-temperature vacuum de-devouring treatment using a clean rotary evaporator for 2 hours to obtain component B; S3. Preparation of silicone potting compound Take 50 parts of component A and 50 parts of component B, mix them evenly with a stirrer to obtain a two-component silicone potting compound.

[0043] A schematic diagram illustrating the active groups of components A and B is shown below. Figure 1 As shown. During mixing, the active group -N=C=O in component A undergoes an addition reaction with the active group -OH in component B. The isocyanate-modified silicone oil (functionality 2) in component A and the silicone oil with a specific hydroxyl structure modified (functionality 4) in component B form a crosslinked system. A schematic diagram of the core typical structure of the crosslinked product is shown below. Figure 2 As shown.

[0044] Example 2 The difference from Example 1 is as follows: In step S3, component B is divided into 20 portions; The remaining conditions and parameters are the same as in Example 1, and a two-component silicone potting compound is obtained.

[0045] Example 3 The difference from Example 1 is as follows: In step S3, component B is divided into 30 portions; The remaining conditions and parameters are the same as in Example 1, and a two-component silicone potting compound is obtained.

[0046] Example 4 The difference from Example 1 is as follows: In step S3, component B is divided into 40 portions; The remaining conditions and parameters are the same as in Example 1, and a two-component silicone potting compound is obtained.

[0047] Example 5 The difference from Example 1 is as follows: In step S3, component B is divided into 60 portions; The remaining conditions and parameters are the same as in Example 1, and a two-component silicone potting compound is obtained.

[0048] Example 6 The difference from Example 1 is as follows: In step S3, component B is divided into 70 portions; The remaining conditions and parameters are the same as in Example 1, and a two-component silicone potting compound is obtained.

[0049] Example 7 The difference from Example 1 is as follows: In step S3, component B is divided into 80 portions; The remaining conditions and parameters are the same as in Example 1, and a two-component silicone potting compound is obtained.

[0050] Example 8 The difference from Example 1 is as follows: In step S3, component B is divided into 90 portions; The remaining conditions and parameters are the same as in Example 1, and a two-component silicone potting compound is obtained.

[0051] Example 9 The difference from Example 1 is as follows: In step S3, component B is divided into 100 portions; The remaining conditions and parameters are the same as in Example 1, and a two-component silicone potting compound is obtained.

[0052] Comparative Example 1 The difference from Example 1 is as follows: In step S2-2, glycerol is replaced with ethylene glycol; The remaining conditions and parameters are the same as in Example 1, and a two-component silicone potting compound is obtained.

[0053] Comparative Example 2 The difference from Comparative Example 1 is: In step S3, component B is divided into 20 portions; The remaining conditions and parameters are the same as those in Comparative Example 1, and a two-component silicone potting compound is obtained.

[0054] Comparative Example 3 The difference from Comparative Example 1 is: In step S3, component B is divided into 30 portions; The remaining conditions and parameters are the same as those in Comparative Example 1, and a two-component silicone potting compound is obtained.

[0055] Comparative Example 4 The difference from Comparative Example 1 is: In step S3, component B is divided into 40 portions; The remaining conditions and parameters are the same as those in Comparative Example 1, and a two-component silicone potting compound is obtained.

[0056] Comparative Example 5 The difference from Comparative Example 1 is: In step S3, component B is divided into 60 portions; The remaining conditions and parameters are the same as those in Comparative Example 1, and a two-component silicone potting compound is obtained.

[0057] Comparative Example 6 The difference from Comparative Example 1 is: In step S3, component B is divided into 70 portions; The remaining conditions and parameters are the same as those in Comparative Example 1, and a two-component silicone potting compound is obtained.

[0058] Comparative Example 7 The difference from Comparative Example 1 is: In step S3, component B is divided into 80 portions; The remaining conditions and parameters are the same as those in Comparative Example 1, and a two-component silicone potting compound is obtained.

[0059] Comparative Example 8 The difference from Comparative Example 1 is: In step S3, component B is divided into 90 portions; The remaining conditions and parameters are the same as those in Comparative Example 1, and a two-component silicone potting compound is obtained.

[0060] Comparative Example 9 The difference from Comparative Example 1 is: In step S3, component B is divided into 100 portions; The remaining conditions and parameters are the same as those in Comparative Example 1, and a two-component silicone potting compound is obtained.

[0061] Test Example 1 The two-component silicone potting compounds obtained in Examples 1-9 and Comparative Examples 1-9 were subjected to viscosity and bond strength tests according to the test standards shown in Table 1. The test results are shown in Table 2.

[0062] Table 1

[0063] Table 2

[0064] The results showed that the adhesive strength of the silicone potting compound obtained in Comparative Example 1 decreased significantly compared with Example 1. This is because the raw material for component B in Comparative Example 1 is a diol. Compared with Example 1, the silicone oil modified by the special hydroxyl structure in component B has changed, resulting in a two-component silicone potting compound obtained in Example 1 having a spatial cage-like crosslinked structure, while the one in Comparative Example 1 has a linear crosslinked structure, thus producing a difference in adhesive strength.

[0065] The difference between the silicone potting compounds in Examples 1-9 lies in the different mass ratios of components A and B. This mixing results in varying degrees of reaction of the functional groups, leading to different adhesive strength characteristics after curing. When components A and B are mixed at a mass ratio of 1:1.4, the resulting two-component silicone potting compound exhibits the optimal adhesive strength.

[0066] The adhesive strength of the silicone potting compounds obtained in Comparative Examples 1-9 was lower than that in Examples 1-9, indicating that the strength of the linear cross-linked silicone potting compound was lower than that of the spatial cage cross-linked silicone potting compound of the present invention.

[0067] This invention modifies the base silicone oil by reacting hydroxyl silicone oil with isocyanate to introduce a large number of isocyanate groups and by reacting carboxyl silicone oil with polyol to introduce a polyhydroxy structure. During mixing, the isocyanate groups in the two components react with the hydroxyl groups to generate urethane groups with extremely high adhesive strength, thereby improving the adhesive performance of the silicone potting compound after curing.

[0068] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A two-component silicone potting compound, characterized in that, The silicone potting compound is obtained by mixing two-component raw materials and includes compounds with the structure shown in Formula I: ； R1 has the structure shown in Equation I-1: ； R3 and R4 are each independently selected from the following (a1)~(a5) divalent groups: (a1) One of 1,2-phenylene, 1,3-phenylene, and 1,4-phenylene; (a2) C1~C12 straight-chain or branched alkylene groups; (a3) C3~C10 cycloalkylene; (a4) has the structure shown in formula a-4, wherein R9 is a C1~C12 straight-chain or branched alkylene group: ； (a5) has the structure shown in equation a-5, where R 10 C1~C12 straight-chain or branched alkylene groups: ； The R2 has the structure shown in Equation I-2: ； R5, R6, R7, and R8 are each independently selected from one of the following: C1-C8 straight-chain or branched alkylene groups, or hydroxy C1-C8 straight-chain or branched alkylene groups containing 1-4 hydroxyl groups. Wherein, 0≤n1≤500, 0≤n2≤500.

2. The silicone potting compound according to claim 1, characterized in that, The two-component preparation raw materials include isocyanate-modified silicone oil and hydroxyl-modified silicone oil.

3. The silicone potting compound according to claim 2, characterized in that, The isocyanate-modified silicone oil has the structure shown in Formula I-1-1: ； And / or, the hydroxyl-modified silicone oil has the structure shown in Formula I-2-1: And / or, the 5≤n1≤200, 5≤n2≤200.

4. The silicone potting compound according to claim 2, characterized in that, The isocyanate-modified silicone oil has the structure shown in Formula I-1-2: ； And / or, the hydroxyl-modified silicone oil has the structure shown in Formula I-2-2: 。 5. A method for preparing a two-component silicone potting compound, characterized in that, Includes the following steps: S1, hydroxyl silicone oil and isocyanate react to obtain component A, wherein the hydroxyl silicone oil has the structure shown in Formula I-1-3, where 5 ≤ n1 ≤ 200: ； S2, carboxyl silicone oil, and polyol react to obtain component B, wherein the carboxyl silicone oil has the structure shown in formula I-2-3, where 5 ≤ n2 ≤ 200: ； S3. Mix component A and component B to obtain the silicone potting compound.

6. The preparation method according to claim 5, characterized in that, The isocyanate mentioned in step S1 is selected from at least one of MDI, HDI, TDI, and HMDI.

7. The preparation method according to claim 5, characterized in that, The polyol mentioned in step S2 is selected from at least one of glycerol, pentaerythritol, trimethylolethane, xylitol, and sorbitol.

8. The preparation method according to claim 5, characterized in that, The mass ratio of hydroxyl silicone oil to isocyanate in step S1 is (9~11):1; And / or, the mass ratio of carboxylated silicone oil to polyol in step S2 is (30~45):

1.

9. The preparation method according to claim 5, characterized in that, In step S3, the mass ratio of component A to component B is 1:(0.4~3); And / or, the mass ratio of component A to component B in step S3 is 1:(0.8~2).

10. The preparation method according to claim 5, characterized in that, The reaction temperature in step S1 is 80~150℃; And / or, the reaction stirring speed in step S1 is 300~700 rpm; And / or, the reaction in step S1 is carried out under vacuum; And / or, the reaction time in step S1 is 2 to 8 hours; And / or, the reaction temperature in step S2 is 30~150℃; And / or, the reaction stirring speed in step S2 is 200~600 rpm; And / or, the reaction in step S2 is carried out under vacuum; And / or, the reaction time in step S2 is 12 to 24 hours.

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