High-compression silicone resin, high-compression silicone conductive adhesive and preparation method

Abstract

The present invention belongs to the technical field of silicone resins and conductive sealing adhesives, specifically relating to high-compression silicone resins, high-compression organosilicon conductive adhesives, and preparation methods. The high-compression silicone resin is a hydroxysiloxane modified with succinic anhydride and has the following structure: #imgabs0#, wherein n and m are integers in the range of 50-200. The present invention provides a high-compression silicone resin, which is a viscous fluid modified with succinic anhydride. It is soft and elastic, and has the general structural formula: [HO(CH3)2SiO1 / 2] n OC(CH2)2CO[1 / 2OSi(CH3)2OH] n The silicone resin has good compression properties.

Description

Technical Field

[0001] The present invention belongs to the technical field of silicone resin and conductive sealing adhesives, and in particular relates to high-compression silicone resin, high-compression organosilicon conductive adhesive and a preparation method thereof. Background Art

[0002] Single-component, room-temperature-curing silicone conductive adhesive absorbs moisture from the air at room temperature, undergoing a condensation reaction to cure. After curing, it exhibits excellent sealing, adhesion, and conductivity, making it widely used in housing gaps for electromagnetic shielding. However, the inclusion of a large amount of conductive metal particles during the production process significantly increases its hardness. In practice, it is difficult to compress and deform during workpiece assembly, which can easily lead to cover deformation and glass breakage, significantly limiting its widespread application. Summary of the Invention

[0003] In response to the above technical problems, the present invention provides, on the one hand, a high-compression silicone resin and a preparation method thereof, wherein the silicone resin has good compression performance; on the other hand, the present invention provides a high-compression silicone conductive adhesive containing the high-compression silicone resin and a preparation method thereof.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A high-compression silicone resin, which is a hydroxysiloxane modified with succinic anhydride and has the following structure:

[0006]

[0007] Wherein, n and m are integers in the range of 50-200.

[0008] The production process of the high-compression silicone resin is as follows:

[0009]

[0010] A method for preparing a high-compression silicone resin comprises adding succinic anhydride, α,ω-dihydroxypolydimethylsiloxane, and dibutyltin oxide into a reaction kettle, adding deionized water, turning on a stirrer, introducing nitrogen, and raising the temperature to 90±5°C for activation.

[0011] After activation, the temperature of the mixture is raised to 180±5° C. and maintained for a period of time; then, the mixture is extracted with dichloromethane, washed with water, and vacuum dried to obtain a high-compression silicone resin.

[0012] Succinic anhydride, α,ω-dihydroxypolydimethylsiloxane and dibutyltin oxide were added into the reactor in sequence according to a molar ratio of 1:2.2:0.003.

[0013] The activation time is 1 hour; the temperature of the mixture is raised to 180±5°C and maintained for 24 hours; the vacuum degree of the vacuum drying is -0.1MPa to -0.5MPa, the temperature is 50°C to 70°C, and the time is 4 to 8 hours.

[0014] A high-compression organic silicon conductive adhesive comprises the above-mentioned high-compression silicone resin, conductive powder, plasticizer, dispersant, filler, cross-linking agent, catalyst and solvent.

[0015] The invention comprises the following components in parts by weight: 20 to 35 parts of high-compression silicone resin, 35 to 65 parts of conductive powder, 0.5 to 1.8 parts of plasticizer, 0.2 to 1.2 parts of dispersant, 0.8 to 4 parts of filler, 2.5 to 7 parts of crosslinking agent, 0.1 to 0.7 parts of catalyst and 3 to 11 parts of solvent.

[0016] The molecular weight of the high-compression silicone resin is 8,000-50,000.

[0017] The conductive powder is one or a combination of two or more of silver-coated copper powder, silver-coated nickel powder, silver-coated aluminum powder, silver-coated glass microbead powder, and nickel-coated graphite powder; the particle size of the conductive powder is between 15 μm and 40 μm;

[0018] The plasticizer is one or a combination of two or more of MDT silicone oil, α,ω-dimethoxypolydimethylsiloxane, dimethyl silicone oil, and phenyl silicone oil;

[0019] The dispersant is one or a combination of two or more of BYK-161, BYK-163, and BYK-110;

[0020] The filler is one or a combination of two or more of fumed silica, diatomaceous earth, bentonite, and nano calcium carbonate;

[0021] The crosslinking agent is one or a combination of two or more of methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, and tetramethoxysilane;

[0022] The catalyst is selected from one of organotin, titanate and its complex, and guanidine alkyl alkoxy silane;

[0023] The solvent is toluene, isoparaffin, solvent oil or a combination of two or more thereof.

[0024] The preparation method comprises the following steps:

[0025] S1. High-compression silicone resin, plasticizer, dispersant, and cross-linking agent are vacuum dispersed in a double planetary mixer for 10 min to 30 min, and then filler is added and vacuum dispersed for 15 min to 40 min to obtain a mixture;

[0026] S2. Add solvent and conductive powder to the mixture obtained in S1 and perform vacuum dispersion for 20-30 minutes; then add catalyst and perform vacuum dispersion in a double planetary mixer for 10-20 minutes to obtain a high-compression conductive sealing adhesive.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention provides a high-compression silicone resin, which is obtained by modifying α,ω-dihydroxypolydimethylsiloxane with succinic anhydride. The silicone resin is a viscous fluid that is soft and elastic, and has the general structural formula: HO(CH3)2SiO1 / 2] n OC(CH2)2CO[1 / 2OSi(CH3)2OH] n The silicone resin has good compression properties.

[0029] Conductive adhesives prepared using this modified siloxane can cure at room temperature. The cured conductive adhesive overcomes the shortcomings of current silicone conductive adhesives, which suffer from high modulus, resistance to deformation, and the resulting high stress between the adhesive and the workpiece after assembly, which can easily lead to workpiece deformation and damage. This material is easily compressible and exhibits low compression set, maintaining excellent adhesion and sealing properties during service. It is suitable for various applications in aviation, aerospace, automotive, construction, and electronic equipment.

[0030] The conductive adhesive material provided by the present invention features a simple preparation process, moderate viscosity, and excellent thixotropy. It can be applied through processes such as scraping and dispensing. The resulting conductive adhesive layer exhibits low modulus, high conductivity, and strong bonding properties, with a compression ratio exceeding 45%, a volume resistivity less than 0.05 Ω·cm, and a shear strength exceeding 1 MPa. This conductive adhesive can meet the high compression ratio requirements of aviation equipment seals, while its volume resistivity and shear strength meet the application requirements of conductive adhesive materials for electromagnetic shielding seals, thus possessing broad application prospects. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0032] Example 1

[0033] High compressibility silicone resin is a hydroxy siloxane modified with succinic anhydride and has the following structure:

[0034]

[0035] Wherein, n and m are integers in the range of 50-200.

[0036] High compressibility silicone resin is a viscous fluid that is soft and elastic. Its general structural formula is:

[0037] HO(CH3)2SiO1 / 2] n OC(CH2)2CO[1 / 2OSi(CH3)2OH] n .

[0038] The production process of high compression silicone resin is as follows:

[0039]

[0040] Preparation of high-compression silicone resin: 0.1 mol of succinic anhydride, 0.22 mol of α,ω-dihydroxypolydimethylsiloxane (hydroxyl content 2%, molecular weight 5000) and 0.0003 mol of dibutyltin oxide were added to the reactor in sequence, 2 mol of deionized water was added, the stirrer was turned on and the stirring speed was adjusted to 120 rpm, nitrogen was introduced, and the temperature was raised to 90±5°C at a rate of 1.5°C / min and activated at this temperature for 1 hour.

[0041] The temperature of the mixture was then raised to 180±5°C at a rate of 2°C / min and maintained at this temperature for 24 hours. The emulsion was then extracted with 1 mol of dichloromethane, the extract was washed three times with water, and vacuum dried to obtain a high-compression silicone resin. The vacuum drying degree was -0.3 MPa, the temperature was 60°C, and the time was 7 hours.

[0042] 25.16 parts by weight of high-compression silicone resin (prepared by the above method), 0.96 parts by weight of α,ω-dimethoxypolydimethylsiloxane, 0.43 parts by weight of BYK-163, and 3.15 parts by weight of methyltrimethoxysilane are vacuum dispersed in a double planetary mixer for 10 minutes to 30 minutes, and 1.91 parts by weight of fumed silica are added and vacuum dispersed for 15 minutes to 40 minutes to obtain a mixture; 5.85 parts by weight of solvent oil and 62.13 parts by weight of conductive powder are added to the mixture and vacuum dispersed for 20 minutes to 30 minutes; then 0.41 parts by weight of catalyst are added, and the mixture is vacuum dispersed in a double planetary mixer for 10 minutes to 20 minutes to obtain a high-compression conductive sealing adhesive.

[0043] Example 2:

[0044] The preparation method of the high-compression conductive sealing adhesive of this embodiment is the same as that of Example 1, except that the hydroxyl content of the α,ω-dihydroxypolydimethylsiloxane in Example 2 is 3% and the molecular weight is 10,000.

[0045] Example 3:

[0046] The preparation method of the high-compression conductive sealing adhesive of this embodiment is the same as that of Example 1, except that the hydroxyl content of the α,ω-dihydroxypolydimethylsiloxane in Example 2 is 4% and the molecular weight is 1000.

[0047] Comparative Example 1: The raw material ratios and steps for preparing the conductive sealing adhesive in Comparative Example 1 are the same as those in Example 1, except that the silicone resin used in Comparative Example 1 is not modified.

[0048] Comparative Example 2: The raw material ratio and steps of Comparative Example 2 are the same as those of Example 2, except that α,ω-dimethoxypolydimethylsiloxane is not added in Comparative Example 2.

[0049] Comparative Example 3: The raw material ratio and steps of Comparative Example 3 are the same as those of Example 3, except that the silicone resin used in Comparative Example 3 is not modified and α,ω-dimethoxypolydimethylsiloxane is not added.

[0050] Test example:

[0051] The bonding performance of the conductive adhesive was compared by shear strength. The applicant used the conductive adhesive prepared in Examples 1-3 and Comparative Examples 1-3 to bond the silicone rubber strip to the aluminum substrate, cured them at room temperature for 7 days, and then tested the shear strength.

[0052] To compare the conductive properties of the conductive adhesive by volume resistivity, the applicant used the conductive adhesives prepared in the above Examples 1-3 and Comparative Examples 1-3 to prepare volume resistivity test samples and conduct tests.

[0053] The compression performance of the conductive adhesive was compared by compression rate and Shore hardness. The applicant used the conductive adhesives prepared in the above Examples 1-3 and Comparative Examples 1-3 to prepare test samples and conduct tests.

[0054] The shear strength of the sample is measured according to GB / T 7124-2008;

[0055] Physical examination resistivity is measured in accordance with GB / T 2439-2001;

[0056] Shore hardness is measured in accordance with GB / T 531.1-2008;

[0057] The compression rate is tested in accordance with GB / T 20671.2-2006.

[0058] The results are shown in Table 1:

[0059] Table 1: Functional index test data of samples obtained from Examples and Comparative Examples

[0060]

[0061] Only the preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the above embodiments.

Claims

1. A high compressibility silicone resin, characterized by: The high-compression silicone resin is a hydroxysiloxane modified with succinic anhydride and has the following structure: Wherein, n and m are integers in the range of 50-200.

2. The high-compression silicone resin according to claim 1, characterized in that: The production process of the high-compression silicone resin is as follows:

3. A method for preparing a high-compression silicone resin according to claim 1, characterized in that: Add succinic anhydride, α,ω-dihydroxypolydimethylsiloxane, and dibutyltin oxide into a reaction kettle, add deionized water, turn on the stirrer, introduce nitrogen, and raise the temperature to 90±5°C for activation at this temperature; After activation, the temperature of the mixture is raised to 180±5° C. and maintained for a period of time; then, the mixture is extracted with dichloromethane, washed with water, and vacuum dried to obtain a high-compression silicone resin.

4. The method for preparing a high-compression silicone resin according to claim 3, wherein: Succinic anhydride, α,ω-dihydroxypolydimethylsiloxane and dibutyltin oxide were added into the reactor in sequence according to a molar ratio of 1:2.2:0.

003.

5. The method for preparing a high-compression silicone resin according to claim 3, wherein: The activation time is 1 hour; the temperature of the mixture is raised to 180±5°C and maintained for 24 hours; the vacuum degree of the vacuum drying is -0.1MPa to -0.5MPa, the temperature is 50°C to 70°C, and the time is 4 to 8 hours.

6. A high-compression silicone conductive adhesive, characterized by: The invention comprises the high-compression silicone resin according to any one of claims 1 to 5, a conductive powder, a plasticizer, a dispersant, a filler, a cross-linking agent, a catalyst and a solvent.

7. The high-compression silicone conductive adhesive according to claim 6, characterized in that: The invention comprises the following components in parts by weight: 20 to 35 parts of high-compression silicone resin, 35 to 65 parts of conductive powder, 0.5 to 1.8 parts of plasticizer, 0.2 to 1.2 parts of dispersant, 0.8 to 4 parts of filler, 2.5 to 7 parts of crosslinking agent, 0.1 to 0.7 parts of catalyst and 3 to 11 parts of solvent.

8. The high-compression silicone conductive adhesive according to claim 6, characterized in that: The molecular weight of the high-compression silicone resin is 8,000-50,000.

9. A high-compression silicone conductive adhesive according to any one of claims 6 to 8, characterized in that: The conductive powder is one or a combination of two or more of silver-coated copper powder, silver-coated nickel powder, silver-coated aluminum powder, silver-coated glass microbead powder, and nickel-coated graphite powder; the particle size of the conductive powder is between 15 μm and 40 μm; The plasticizer is one or a combination of two or more of MDT silicone oil, α,ω-dimethoxypolydimethylsiloxane, dimethyl silicone oil, and phenyl silicone oil; The dispersant is one or a combination of two or more of BYK-161, BYK-163, and BYK-110; The filler is one or a combination of two or more of fumed silica, diatomaceous earth, bentonite, and nano calcium carbonate; The crosslinking agent is one or a combination of two or more of methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, and tetramethoxysilane; The catalyst is selected from one of organotin, titanate and its complex, and guanidine alkyl alkoxy silane; The solvent is toluene, isoparaffin, solvent oil or a combination of two or more thereof.

10. The preparation method of the organic silicone conductive adhesive according to claim 6, characterized in that: The following steps are involved: S1. High-compression silicone resin, plasticizer, dispersant, and cross-linking agent are vacuum dispersed in a double planetary mixer for 10 min to 30 min, and then filler is added and vacuum dispersed for 15 min to 40 min to obtain a mixture; S2. Add solvent and conductive powder to the mixture obtained in S1 and perform vacuum dispersion for 20-30 minutes; Then, a catalyst is added and vacuum dispersion is carried out in a double planetary mixer for 10 minutes to 20 minutes to obtain a high-compression conductive sealing adhesive.

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