Organic silicon tackifier and preparation method of organic silicon pressure-sensitive adhesive using organic silicon tackifier

Abstract

The invention relates to an organic silicon tackifier and an organic silicon pressure-sensitive adhesive preparation method using the same, the organic silicon tackifier is prepared from methyl hydrogen-containing silicon resin and a vinyl trimethoxy silane coupling agent through a hydrosilylation reaction, and the organic silicon tackifier is added into an organic silicon pressure-sensitive adhesive system. The high-performance organic silicon pressure-sensitive adhesive tape is prepared through blending, coating, solvent volatilization and heating crosslinking. The organic silicon tackifier in the preparation method disclosed by the invention is rich in methoxyl functional groups with relatively high activity, and the functional groups enhance the interaction between the organic silicon pressure-sensitive adhesive and the surface of an adhered material, so that the adhesion performance of the organic silicon pressure-sensitive adhesive to the adhered surface can be improved; the comprehensive optimization of the pressure-sensitive adhesive in the aspects of peel strength, permanent adhesion, shear strength, heat resistance and the like is realized.

Description

Technical Field

[0001] This invention relates to the field of silicone rubber technology, and in particular to a method for preparing an organosilicon pressure-sensitive adhesive containing a multifunctional organosilicon tackifier. Background Technology

[0002] Silicone pressure-sensitive adhesive is a special type of adhesive composed of silicone rubber and silicone resin (such as MQ resin). Its unique chemical structure distinguishes it from other organic polymer adhesives. The main structure of this adhesive is a polysiloxane skeleton composed of silicon-oxygen bonds. This structure not only has long bond lengths and flexible bond angles, but also exhibits high flexibility, giving silicone pressure-sensitive adhesive excellent chemical properties, such as chemical corrosion resistance, high temperature resistance, and aging resistance.

[0003] However, due to the polydimethylsiloxane structure of the main component of this type of silicone pressure-sensitive adhesive, there are fewer functional groups in the system that interact with the surface of the substrate being bonded, resulting in weak adhesion to various materials and limiting its application range. Although the addition of silicone resin (such as MQ resin) can improve the wettability to the substrate, the lack of chemical bonding with the substrate surface means that the adhesion is still mainly based on physical adsorption and has limited strength. Therefore, the prepared silicone pressure-sensitive adhesive has a long bonding time and low peel force. Furthermore, under dynamic stress (such as shear and peel), the adhesive layer is prone to creep or cohesive failure, further reducing the peel force. Summary of the Invention

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing an organosilicon tackifier includes the following steps: S1 involves stirring and heating vinyltrimethoxysilane, solvent, and platinum catalyst under a nitrogen atmosphere to obtain a mixture; S2 involves uniformly mixing methyl hydrogen-containing silicone resin and solvent, then dripping the mixture into the mixture described in S1 under constant pressure, and maintaining the temperature for 3-6 hours. S3 adds activated carbon to the S2 material and mixes for 1-2 hours. The platinum catalyst is then removed by filtration. The filtrate is then distilled under reduced pressure to remove unreacted monomers and solvents, yielding an organosilicon thickener. The mass ratio of the vinyltrimethoxysilane to the methyl hydrogen-containing silicone resin is (1~1.2):1.

[0005] In this invention, a methyl silicone resin-ethylenetrimethoxysilane organosilicon tackifier (MQ-ETMS) is synthesized by hydrosilylation reaction between a vinyltrimethoxysilane coupling agent and a methyl hydrogen-containing silicone resin. The reaction formula is shown in Formula 1. (Equation 1) In this reaction, the methyl hydrosilicone resin contains Si-H bonds, which undergo an addition reaction with the vinyl group in vinyltrimethoxysilane under the above conditions. After the vinyl group in vinyltrimethoxysilane reacts with the Si-H bonds in the methyl hydrosilicone resin, the double bond of the vinyl group opens, forming a new C-Si bond. The double bond of the vinyl group no longer exists. The newly formed C-Si bond allows the methyl hydrosilicone resin and vinyltrimethoxysilane to be chemically bonded together, forming a chemical bond and enhancing the adhesion. At the same time, the synthesized organosilicon tackifier is rich in methoxy functional groups. These, as highly active groups, can condense with the hydroxyl groups on the surface of the substrate to form a chemical bond, forming a stable covalent bond, which enhances the interaction force between the organosilicon pressure-sensitive adhesive and the substrate, thereby improving the peel force. That is, after the addition reaction, the types and numbers of functional groups interacting with the surface of the substrate on the obtained organosilicon tackifier are changed. When applied to the thickening of organosilicon pressure-sensitive adhesive, it can enhance the interaction force with the surface of the substrate.

[0006] Furthermore, the solvent is toluene or xylene, and the mass of the solvent is 2 to 3 times the total mass of vinyltrimethoxysilane and methyl hydrogen-containing silicone resin.

[0007] Furthermore, the catalyst is 0.5% to 2% of the total mass of vinyltrimethoxysilane and methyl hydrogen silicone resin.

[0008] The present invention also provides an organosilicon pressure-sensitive adhesive using an organosilicon tackifier prepared by the above method.

[0009] The preparation method of the above-mentioned silicone pressure-sensitive adhesive includes the following steps: T1 Methyl MQ silicone resin, 107 silicone rubber and toluene are mixed evenly under nitrogen protection, and a catalyst is added. The mixture is stirred and heated to carry out a condensation reaction. After the reaction, water and toluene are separated to obtain an organosilicon pressure-sensitive adhesive liquid. T2 mixes the silicone tackifier, the silicone pressure-sensitive adhesive base liquid, toluene and initiator to obtain a silicone pressure-sensitive adhesive solution. After uniformly coating the silicone pressure-sensitive adhesive solution onto the substrate, solvent evaporation and thermal crosslinking are performed to obtain silicone pressure-sensitive adhesive. The mass ratio of 107 silicone rubber to methyl MQ silicone resin is 100:(30~100), the mass of toluene is 0.8~1.2 times the total mass of 107 silicone rubber and methyl MQ silicone resin, and the mass ratio of the organosilicon tackifier to the organosilicon pressure-sensitive adhesive base liquid is (1~5):100.

[0010] Furthermore, in T1, the catalyst is any one of acetic acid, triethylamine, or dibutyltin dibutylsilicate, and the catalyst mass is 0.5% to 2% of the total mass of 107 silicone rubber and methyl MQ silicone resin. Furthermore, in T1, the condensation reaction temperature is 110~130 ℃, the reaction time is 1~3 h, and the stirring rate is 300 r / min.

[0011] Furthermore, in T2, the initiator is 2,4-dichlorobenzoyl peroxide or benzoyl peroxide, and the mass of the initiator is 3% to 6% of the mass of the base liquid.

[0012] Furthermore, in T2, the mixing time is 10-30 min and the stirring rate is 1500 r / min.

[0013] Furthermore, in T2, the solvent evaporation temperature is 60~100℃, the evaporation time is 60~150s, the crosslinking temperature is 150~180℃, the crosslinking time is 80~120s, and the coating thickness on the substrate after solvent evaporation and crosslinking is 15~30μm.

[0014] The beneficial effects of this invention are as follows: The silicone tackifier of the present invention is prepared by hydrosilylation reaction of methyl hydrosilicone resin and vinyltrimethoxysilane coupling agent. After the vinyl group in vinyltrimethoxysilane reacts with the Si-H bond in methyl hydrosilicone resin, a new C-Si bond is formed, forming a chemical bond and enhancing the adhesion. The tackifier after the reaction is also rich in methoxy functional groups. The methoxy group can condense with the hydroxyl group on the surface of the substrate to form a stable covalent bond, which enhances the interaction force between the silicone pressure-sensitive adhesive and the substrate. It can quickly form a strong bond with the surface of the substrate, shorten the bonding time, and improve the holding time.

[0015] The silicone tackifier prepared in this invention, when added to a silicone pressure-sensitive adhesive system, can improve the interfacial bonding speed between the silicone pressure-sensitive adhesive and the substrate by controlling the crosslinking density and interfacial chemical bonding, thus achieving comprehensive optimization of the pressure-sensitive adhesive in terms of peel strength, holding power, shear strength, and heat resistance. Detailed Implementation

[0016] The present invention will be further illustrated below with reference to the embodiments, the purpose of which is to better understand the content of the present invention and to demonstrate the essential features of the present invention. Therefore, the examples given should not be regarded as a limitation on the scope of protection of the present invention.

[0017] Example 1 Preparation of organosilicon tackifier: 15 g of vinyltrimethoxysilane, 30 g of toluene, and 0.15 g of Karstedt platinum catalyst (CAS No.: 81032-58-8) were added to a three-necked flask equipped with a condenser and a magnetic stirrer. The mixture was stirred and heated to 70 °C under a nitrogen atmosphere. Then, 15 g of methyl hydrogen-containing silicone resin (0.7 mol / 100 g hydrogen content) and 30 g of toluene were mixed evenly and placed in a constant pressure dropping funnel. The mixture was then added dropwise to the three-necked flask and kept at this temperature for 3 h. The solution was then mixed with activated carbon for 1 h and filtered through a 0.22 µm filter to remove residual platinum catalyst. The filtrate was then distilled under reduced pressure to remove unreacted monomers and toluene, yielding a colorless and transparent organosilicon tackifier (MQ-ETMS).

[0018] Preparation of silicone pressure-sensitive adhesive: In a three-necked flask equipped with a water separator and mechanical stirrer, add 30 parts of methyl MQ silicone resin (M / Q = 0.65-0.75), 100 parts of 107 silicone rubber (molecular weight approximately 500,000), and 156 parts of toluene. Stir under nitrogen protection until homogeneous. Then add 0.65 parts of dibutyltin dilaurate, controlling the stirring rate at 300 r / min. Heat to 110 ℃ and allow the condensation reaction to proceed for 1 h. Reflux the mixture to separate water and toluene, yielding a colorless, transparent, viscous silicone pressure-sensitive adhesive base solution. Add 100 parts of the silicone pressure-sensitive adhesive base solution, 70 parts of toluene solvent, 1 part of silicone tackifier, and 3 parts of 2,4-dichlorobenzoyl peroxide (DCBP) and mix using a high-speed stirrer at a stirring speed of 1500 rpm. The silicone pressure-sensitive adhesive solution was obtained by high-speed mixing at r / min for 10 min. Subsequently, the solution was coated onto a PET film in a three-necked flask. After coating, the sample was placed in an oven at 60℃ for 150 s and then subjected to thermal crosslinking at 150℃ for 120 s, forming a 15 μm thick coating on the PET film.

[0019] Example 2 Preparation of organosilicon tackifier: 15 g of vinyltrimethoxysilane, 41 g of toluene, and 0.55 g of Karstedt platinum catalyst (CAS No.: 81032-58-8) were added to a three-necked flask equipped with a condenser and a magnetic stirrer. The mixture was stirred and heated to 95 °C under a nitrogen atmosphere. Then, 12.5 g of methyl hydrogen-containing silicone resin (hydrogen content 0.7 mol / 100 g) and 41 g of toluene were mixed evenly and placed in a constant pressure dropping funnel. The mixture was then added dropwise to the three-necked flask and kept at this temperature for 6 h. The solution was then mixed with activated carbon for 2 h and filtered through a 0.22 µm filter to remove residual platinum catalyst. The filtrate was then distilled under reduced pressure to remove unreacted monomers and toluene, yielding a colorless and transparent organosilicon tackifier (MQ-ETMS).

[0020] Preparation of silicone pressure-sensitive adhesive: In a three-necked flask equipped with a water separator and mechanical stirrer, add 100 parts of methyl MQ silicone resin (M / Q = 0.65-0.75), 100 parts of 107 silicone rubber (molecular weight approximately 500,000), and 160 parts of toluene. Stir under nitrogen protection until homogeneous. Then add 40 parts of dibutyltin dilaurate, controlling the stirring speed at 300 r / min. Heat to 130 ℃ and allow the condensation reaction to proceed for 3 h. Reflux and separate water and toluene to obtain a colorless, transparent, viscous silicone pressure-sensitive adhesive base liquid. Add 100 parts of the silicone pressure-sensitive adhesive base liquid, 70 parts of toluene solvent, 5 parts of silicone tackifier, and 6 parts of 2,4-dichlorobenzoyl peroxide (DCBP) and mix using a high-speed stirrer at a stirring speed of 1500 rpm. The silicone pressure-sensitive adhesive solution was obtained by high-speed mixing at r / min for 30 min. Subsequently, the solution was coated onto a PET film in a three-necked flask. After coating, the sample was placed in an oven at 100 ℃ for 60 s and then subjected to thermal crosslinking at 180 ℃ for 80 s, forming a 30 μm thick coating on the PET film.

[0021] Example 3 Preparation of organosilicon thickener: 15 g of vinyltrimethoxysilane, 36 g of toluene, and 0.38 g of Karstedt platinum catalyst (CAS No.: 81032-58-8) were added to a three-necked flask equipped with a condenser and a magnetic stirrer. The mixture was stirred and heated to 85 °C under a nitrogen atmosphere. Then, 14 g of methyl hydrogen-containing silicone resin (0.7 mol / 100 g hydrogen content) and 36 g of toluene were mixed evenly and placed in a constant pressure dropping funnel. The mixture was then added dropwise to the three-necked flask and kept at this temperature for 5 h. The solution was then mixed with activated carbon for 1.5 h and filtered through a 0.22 µm filter to remove residual platinum catalyst. The filtrate was then distilled under reduced pressure to remove unreacted monomers and toluene, yielding a colorless and transparent organosilicon thickener (MQ-ETMS).

[0022] Preparation of silicone pressure-sensitive adhesive: In a three-necked flask equipped with a water separator and a mechanical stirrer, add 40 parts of methyl MQ silicone resin (M / Q = 0.65-0.75), 100 parts of 107 silicone rubber (molecular weight approximately 500,000), and 140 parts of toluene. Stir under nitrogen protection until homogeneous. Then add 40 parts of dibutyltin dilaurate, controlling the stirring rate at 300 r / min. Heat to 125 ℃ and allow the condensation reaction to proceed for 2 h. Reflux the mixture to separate water and toluene, yielding a colorless, transparent, viscous silicone pressure-sensitive adhesive base solution. Add 100 parts of the silicone pressure-sensitive adhesive base solution, 70 parts of toluene solvent, 2.5 parts of silicone tackifier, and 4.5 parts of 2,4-dichlorobenzoyl peroxide (DCBP) and mix using a high-speed stirrer at 1500 r / min for 20 seconds. After min, an organosilicon pressure-sensitive adhesive solution was obtained. Subsequently, it was coated onto a PET film in a three-necked flask. After coating, the sample was placed in an oven at 80°C for 90 s and then subjected to thermal crosslinking at 160°C for 90 s, forming a 25 μm thick coating on the PET film.

[0023] Comparative Example 1: Compared with Example 3, no silicone tackifier (MQ-ETMS) was added in the preparation of the silicone pressure-sensitive adhesive, and the other steps and conditions were the same as in Example 3.

[0024] Comparative Example 2: Compared with Example 3, the amount of silicone tackifier (MQ-ETMS) in the preparation of the silicone pressure-sensitive adhesive was 6 parts.

[0025] Comparative Example 3: Compared with Example 3, the silicone tackifier (MQ-ETMS) in the preparation of the silicone pressure-sensitive adhesive was replaced with vinyltrimethoxysilane (CAS No. 2768-02-7).

[0026] In Comparative Example 4, compared to Example 3, the silicone tackifier (MQ-ETMS) was replaced with vinyl MQ resin (CAS No. 68584-83-8) in the preparation of the silicone pressure-sensitive adhesive.

[0027] Performance testing: The silicone pressure-sensitive adhesive samples prepared in the above embodiments and comparative examples were tested for peel strength, shear strength, and holding time. The peel strength test was performed according to ASTM-D3330. The pressure-sensitive adhesive tape was fully bonded to a 15mm × 30mm silicone plate, rolled with a 2kg pressure roller, and then subjected to a 180° peel test at 50mm / min on a universal testing machine. The shear strength test was performed according to GB / T 33332-2016, using the lap shear method. The pressure-sensitive adhesive covered an area of ​​12.5mm × 25mm on the steel plate surface. The maximum breaking force was determined at a tensile speed of 2mm / min. The holding time strength test was performed according to GB / T 4851-2014. The front 2.5cm of a 7.5cm × 2.5cm sample was adhered to the test plate, rolled with a 2kg roller, and then suspended under a 1kg load. The time for complete sample detachment was recorded (>72h was counted as 72h).

[0028] Table 1 Performance test results of silicone pressure-sensitive adhesive samples ①-⑦ Preparation Example Peel strength N / 25mm Shear strength (kPa) Holding time h Example 1 12.2 212 >72 Example 2 >16.0 251 >72 Example 3 >16.0 238 >72 Comparative Example 1 4.2 152 1 Comparative Example 2 11.7 231 66 Comparative Example 3 8.8 203 53 Comparative Example 4 6.3 198 31 As shown in Table 1, the silicone pressure-sensitive adhesive samples prepared in Examples 1-3 exhibited significant improvements in peel strength, shear strength, and holding time. All the tapes could stably support a 1000 g weight for over 72 hours. The silicone pressure-sensitive adhesive samples prepared in Examples 2-3 showed a 180° peel strength exceeding 16.0 N / 25 mm. This indicates that the preparation and addition of the silicone tackifier in this method effectively optimizes the overall performance of the prepared silicone pressure-sensitive adhesive.

[0029] The test results of Example 3 and Comparative Example 1 show that the 180° peel strength in Example 3 exceeds 16.0 N / 25 mm, and the shear strength reaches 238 kPa. Compared with Comparative Example 1, the 180° peel strength is increased by 280.9%, the shear strength is increased by 56.6%, and the holding time is increased from 1 h to more than 72 h. The addition of the silicone tackifier in the preparation method of this invention comprehensively optimizes the performance of silicone pressure-sensitive adhesive in terms of peel strength, holding power, and shear strength.

[0030] Compared with Comparative Example 2, the peel strength and holding time of Comparative Example 2 decreased. This may be because the high content of silicone tackifier affects the molecular structure and rheological properties of the pressure-sensitive adhesive, changes the cohesive force of the pressure-sensitive adhesive, and reduces the cohesive strength of the pressure-sensitive adhesive. When subjected to external force, the pressure-sensitive adhesive is prone to cohesive failure, resulting in a decrease in holding and peel strength.

[0031] Comparing Example 3 with Comparative Examples 3 and 4, it can be seen that, compared with the use of traditional tackifiers, the use of the silicone tackifier of the present invention to prepare silicone pressure-sensitive adhesives significantly improves the performance of silicone pressure-sensitive adhesives in terms of peel strength, holding power and shear strength.

[0032] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0033] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing an organosilicon tackifier, characterized in that, Includes the following steps: S1 involves stirring and heating vinyltrimethoxysilane, solvent, and catalyst under a nitrogen atmosphere to 70-95 °C to obtain a mixture; S2 involves uniformly mixing methyl hydrogen-containing silicone resin and solvent, then dripping the mixture into the mixture described in S1 under constant pressure, and maintaining the temperature for 3-6 hours. S3 adds activated carbon to the S2 material and mixes for 1-2 hours. The platinum catalyst is then removed by filtration. The filtrate is then distilled under reduced pressure to remove unreacted monomers and solvents, yielding an organosilicon thickener. The mass ratio of the vinyltrimethoxysilane to the methyl hydrogen-containing silicone resin is (1~1.2):

1.

2. The method for preparing the organosilicon tackifier according to claim 1, characterized in that, The solvent is toluene or xylene, and the mass of the solvent is 2 to 3 times the total mass of vinyltrimethoxysilane and methyl hydrogen-containing silicone resin.

3. The method for preparing the organosilicon thickener according to claim 1, characterized in that, The catalyst is a platinum catalyst, and the mass of the catalyst is 0.5% to 2% of the total mass of vinyltrimethoxysilane and methyl hydrogen-containing silicone resin.

4. An organosilicon pressure-sensitive adhesive, characterized in that, The organosilicon thickener prepared using any one of claims 1-3.

5. A method for preparing the organosilicon pressure-sensitive adhesive as described in claim 4, characterized in that, Includes the following steps: T1 Methyl MQ silicone resin, 107 silicone rubber and toluene are mixed evenly under nitrogen protection, and a catalyst is added. The mixture is stirred and heated to carry out a condensation reaction. After the reaction, water and toluene are separated to obtain an organosilicon pressure-sensitive adhesive liquid. T2 mixes the silicone tackifier, the silicone pressure-sensitive adhesive base liquid, toluene solvent and initiator to obtain a silicone pressure-sensitive adhesive solution. After uniformly coating the silicone pressure-sensitive adhesive solution onto the substrate, solvent evaporation and thermal crosslinking are performed to obtain silicone pressure-sensitive adhesive. The mass ratio of 107 silicone rubber to methyl MQ silicone resin is 100:(30~100), the mass of toluene is 0.8~1.2 times the total mass of 107 silicone rubber and methyl MQ silicone resin, and the mass ratio of the organosilicon tackifier to the organosilicon pressure-sensitive adhesive base liquid is (1~5):

100.

6. The preparation method according to claim 5, characterized in that, In T1, the catalyst is any one of acetic acid, triethylamine, or dibutyltin dibutylsilicate, and the mass of the catalyst is 0.5% to 2% of the total mass of 107 silicone rubber and methyl MQ silicone resin.

7. The preparation method according to claim 5, characterized in that, In T1, the condensation reaction temperature is 110~130 ℃, the reaction time is 1~3 h, and the stirring rate is 300 r / min.

8. The preparation method according to claim 5, characterized in that, In T2, the initiator is 2,4-dichlorobenzoyl peroxide or benzoyl peroxide, and the mass of the initiator is 3% to 6% of the mass of the base liquid.

9. The preparation method according to claim 5, characterized in that, In T2, the mixing time is 10-30 min and the stirring rate is 1500 r / min.

10. The preparation method according to claim 5, characterized in that, In T2, the solvent evaporation temperature is 60~100℃, the evaporation time is 60~150s, the crosslinking temperature is 150~180℃, the crosslinking time is 80~120s, and the coating thickness on the substrate after solvent evaporation and crosslinking is 15~30μm.