Ultraviolet curing organic silicon adhesive, preparation method and application

Abstract

The invention discloses an ultraviolet curing organic silicon adhesive, a preparation method and application, and belongs to the technical field of high polymer materials. Wherein the adhesive comprises a sulfydryl organic silicon material, an acrylate organic silicon material, vinyl modified polyvinyl chloride and other components, and the preparation method comprises the following steps: S1, preparing the vinyl modified polyvinyl chloride; s2, preparation of sulfydryl organic silicon grafted vinyl modified polyvinyl chloride; and S3, preparing the ultraviolet light curing organic silicon adhesive. According to the prepared ultraviolet curing organic silicon adhesive, a sulfydryl organic silicon material is grafted to vinyl modified polyvinyl chloride through a thiol-ene reaction, and acrylate organic silicon is connected, so that the light curing speed, the high and low temperature resistance and the adhesion of the adhesive are remarkably improved. The invention solves the problems of low curing speed and poor adhesive property caused by poor compatibility of polyvinyl chloride and an organic silicon material, and has the potential of being applied to preparation of a pressure-sensitive adhesive, a sealing adhesive, a laminating adhesive and a pouring sealant.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer materials, in particular to a kind of ultraviolet light cured silicone adhesive, preparation method and application. BACKGROUND

[0002] Due to excellent thermal stability, weather resistance, electrical insulation and aging resistance, silicone materials have become an important material in the field of special adhesives. However, traditional silicone adhesives mainly rely on thermal curing or moisture curing, which has the disadvantages of low curing efficiency and high energy consumption, and is difficult to meet the actual use requirements of industry. Ultraviolet light curing technology has gradually become an important curing method for adhesives due to its fast curing speed, low energy consumption, environmental friendliness and mild reaction conditions. Among them, the thiol-ene click reaction initiated by ultraviolet light not only has fast reaction rate, high efficiency, energy saving and can be carried out at room temperature, but also has the remarkable advantages of being insensitive to oxygen, so it has been widely studied in the fields of coatings, optics and medical materials.

[0003] Polyvinyl chloride is a widely used polymer with high mechanical strength, good flame retardancy, chemical corrosion resistance and low cost. The adhesive prepared from polyvinyl chloride has good bonding strength and fast curing speed, so it is applied in many industrial fields.

[0004] The existing ultraviolet light cured silicone adhesive may produce a large volume shrinkage during curing, which affects its long-term bonding reliability. Secondly, the curing speed, cohesive force, high and low temperature resistance of the adhesive are difficult to effectively balance. At the same time, the compatibility problem of silicone material and polyvinyl chloride also seriously restricts the development of this type of adhesive material.

[0005] Therefore, it is urgent to develop an ultraviolet light cured silicone adhesive with fast curing speed, strong adhesion, low shrinkage, excellent high and low temperature resistance and aging resistance, etc. to solve the above problems. SUMMARY

[0006] Therefore, the present application provides an ultraviolet light cured silicone adhesive, a preparation method and an application to solve the problem of slow curing speed and poor bonding performance of the adhesive due to poor compatibility of polyvinyl chloride and silicone material in the prior art.

[0007] In order to achieve the above purpose, the present application provides the following technical solutions: According to the first aspect of the present application, an ultraviolet light cured silicone adhesive is provided, which comprises a thiol silicone material, an acrylate silicone material and a vinyl modified polyvinyl chloride.

[0008] Further, the mercapto organosilicon material is mercapto silicone oil with a mercapto content of 8%, and the acrylate organosilicon material is bis-3-methyl methacryloxypropyl tetramethyl disiloxane.

[0009] Further, the mass ratio of the mercapto organosilicon material, the acrylate organosilicon material and the vinyl modified polyvinyl chloride is 1: (1-3): (1-2.5).

[0010] Further, the mass ratio of the mercapto organosilicon material, the acrylate organosilicon material and the vinyl modified polyvinyl chloride is 1:3:2.3.

[0011] According to the second aspect of the present application, a preparation method of the ultraviolet light curing organosilicon adhesive is provided, comprising the following steps: S1, preparation of the vinyl modified polyvinyl chloride; S2, preparation of the mercapto organosilicon grafted vinyl modified polyvinyl chloride; S3, preparation of the ultraviolet light curing organosilicon adhesive: The mercapto organosilicon grafted vinyl modified polyvinyl chloride and tetrahydrofuran are mixed, and stirred for 6 h; the mercapto silicone oil with a mercapto content of 8% and bis-3-methyl methacryloxypropyl tetramethyl disiloxane are added, and then the photoinitiator with a total solid mass of 3%, the silane coupling agent with a total solid mass of 1% and the leveling agent with a total solid mass of 0.1% are added; the mixture is stirred at room temperature at 500-600 rpm in the dark for 4-6 h, and the ultraviolet light curing organosilicon adhesive is obtained.

[0012] Further, the step S1 comprises the following steps: a. In a three-necked flask, polyvinyl chloride, calcium-zinc stabilizer and tetrahydrofuran are mixed in a mass-volume ratio of 5 g: 0.1 g: 100 mL, a condenser tube is installed, and the mixture is stirred at 500-600 rpm in a nitrogen atmosphere under an oil bath at 50°C for 3-4 h; b. Allyl mercaptan with a mass of 15-20% of the polyvinyl chloride is added, and then azobisisobutyronitrile is added after uniform mixing, the mass ratio of the allyl mercaptan to the azobisisobutyronitrile is (30-40): 1; the temperature is increased to 65°C, and the reaction is carried out under reflux in the dark for 8 h; c. After the reaction is completed, the mixture is cooled to room temperature, and then slowly added to methanol for precipitation, the precipitate is filtered, washed with methanol for 3 times, and dried at 40°C under vacuum for 24 h, and the vinyl modified polyvinyl chloride is obtained.

[0013] Further, the step S2 comprises the following steps: a. In a three-necked flask, mercapto silicone oil with a mercapto content of 8%, vinyl modified polyvinyl chloride, calcium-zinc stabilizer and tetrahydrofuran are added; a condenser tube is installed, and the mixture is stirred at 500-600 rpm in a nitrogen atmosphere under an oil bath at 50°C for 3-4 h; b. After the end of stirring, 0.2% of azobisisobutyronitrile of mercaptosilicone oil is added, the temperature is raised to 65°C, and the reaction is carried out under light reflux for 6h; c. After the reaction is completed, the temperature is cooled to room temperature, the reaction solution is slowly added to methanol for precipitation, filtration is carried out to obtain the precipitate, the precipitate is washed with methanol for 3 times, and vacuum drying is carried out at 40°C for 24h to obtain mercaptosilicone grafted vinyl modified polyvinyl chloride.

[0014] Further, in step S2, the mass-volume ratio of the mercaptosilicone oil with a mercapto content of 8%, the vinyl modified polyvinyl chloride, the calcium-zinc stabilizer and the tetrahydrofuran is 7g:10g:0.1g:60mL.

[0015] Further, in step S3, the mass-volume ratio of the mercaptosilicone grafted vinyl modified polyvinyl chloride, the mercaptosilicone oil with a mercapto content of 8% and the acrylate silicone oil and the tetrahydrofuran is 5g:7g:7g:10mL, the photoinitiator in step S3 is Irgacure 184, the silane coupling agent is KH-570, and the leveling agent is BYK-333. According to a third aspect of the present application, the application provides a use of the ultraviolet light cured silicone adhesive in preparing pressure sensitive adhesive, sealant, laminating adhesive and pouring sealant.

[0016] The present application has the following advantages: 1. The mercapto group in mercaptosilicone can form thiol-ene reaction with vinyl under the condition of photo initiation, which provides flexibility and temperature resistance for the system as a crosslinking agent, and the thiol-ene reaction has the advantages of high efficiency, rapidness and less side reactions.

[0017] 2. The acrylate group in acrylate silicone has high reactivity, which preferentially reacts with mercapto group during the light curing, and the reaction speed is fast and the efficiency is high, which effectively improves the light curing speed of the system, and the long chain silicone structure further improves the content of flexible Si-O-Si segment in the system, and cooperates with Si-SH to enhance the temperature resistance and weather resistance of the system; at the same time, the flexible extension chain of the long chain silicone can effectively reduce the crosslinking density of the system and improve the flexibility of the adhesive layer.

[0018] 3. The present application adopts a step-by-step method: (1) first, the polyvinyl chloride is modified to create reaction sites for subsequent grafting of silicone; (2) the mercaptosilicone is grafted with vinyl; (3) the acrylate silicone is reacted with the grafted product and the thiol-ene reaction is carried out under the ultraviolet light initiation to obtain the ultraviolet light cured silicone adhesive. The present application effectively solves the problem that the groups available as reaction sites on polyvinyl chloride are only C-Cl groups, but the reactivity is low and the compatibility with silicone is poor, and significantly improves the weather resistance, bonding strength and curing speed of the system.

[0019] 4. The system contains abundant functional groups such as -Cl, -SH and acrylate groups, which can form covalent bonds or intermolecular forces with the active groups on the substrate surface. At the same time, polyvinyl chloride provides the system with high strength and high modulus, and the flexible cross-linked network of organosilicon segments provides extremely high elongation at break and toughness. The combination of the two forms a rigid-flexible network structure, which is the basis for the adhesive prepared by this invention to have good adhesion, high and low temperature resistance and low shrinkage. Attached Figure Description

[0020] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0021] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0022] Figure 1 A curing time diagram of the UV-curable silicone adhesive provided by this invention; Figure 2 The volume shrinkage rate diagram of the UV-curable silicone adhesive provided by the present invention. Detailed Implementation

[0023] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] According to a first aspect of the present invention, a UV-curable silicone adhesive is provided, comprising a mercapto silicone material, an acrylate silicone material, and a vinyl-modified polyvinyl chloride.

[0025] Among them, the mercapto-based organosilicon material is mercapto-silicone oil with a mercapto content of 8%, and the acrylate-based organosilicon material is bis-3-methylpropenyloxypropyltetramethyldisiloxane.

[0026] The mass ratio of mercapto-based silicone material, acrylate-based silicone material and vinyl-modified polyvinyl chloride is 1:(1-3):(1-2.5).

[0027] The mass ratio of mercapto-based silicone material, acrylate-based silicone material, and vinyl-modified polyvinyl chloride is 1:3:2.3.

[0028] According to a second aspect of the present invention, a method for preparing a UV-curable silicone adhesive is provided, comprising the following steps: S1. Preparation of vinyl-modified polyvinyl chloride; S2, Preparation of mercapto-organosilicon-grafted vinyl-modified polyvinyl chloride; S3. Preparation of UV-curable silicone adhesive: Thiol-based organosilicon grafted with vinyl-modified polyvinyl chloride and tetrahydrofuran were mixed and stirred for 6 hours. Thiol-based silicone oil with a thiol content of 8% and bis-3-methylpropenyloxypropyltetramethyldisiloxane were added, followed by photoinitiator with a total solid mass of 3%, silane coupling agent with a total solid mass of 1%, and leveling agent with a total solid mass of 0.1%. The mixture was stirred at 500-600 rpm in the dark at room temperature for 4-6 hours to obtain UV-curable organosilicon adhesive.

[0029] Step S1 includes the following steps: a. Mix polyvinyl chloride, calcium zinc stabilizer and tetrahydrofuran in a three-necked flask at a mass-to-volume ratio of 5g:0.1g:100mL, install a condenser, and magnetically stir at 500-600rpm for 3-4 hours in a nitrogen atmosphere under an oil bath at 50℃. b. Add 15-20% of allyl mercaptan by weight of polyvinyl chloride, mix well, and then add azobisisobutyronitrile. The mass ratio of allyl mercaptan to azobisisobutyronitrile is (30-40):1. Heat to 65℃ and reflux in the dark for 8 hours. c. After the reaction is complete, cool to room temperature, slowly add the reaction solution to methanol to precipitate, filter to collect the precipitate, wash with methanol 3 times, and dry under vacuum at 40°C for 24 hours to obtain vinyl-modified polyvinyl chloride.

[0030] Step S2 includes the following steps: a. Add mercapto-silicone oil with a mercapto content of 8%, vinyl-modified polyvinyl chloride, calcium-zinc stabilizer and tetrahydrofuran to a three-necked flask; install a condenser and magnetically stir at 500-600 rpm for 3-4 hours in a nitrogen atmosphere under an oil bath at 50°C. b. After stirring, add 0.2% (by weight) of azobisisobutyronitrile to mercaptosilicone oil, heat to 65°C, and reflux in the dark for 6 hours; c. After the reaction is complete, cool to room temperature, slowly add the reaction solution to methanol to precipitate, filter to collect the precipitate, wash with methanol 3 times, and vacuum dry at 40℃ for 24h to obtain mercapto-organosilicon-grafted vinyl-modified polyvinyl chloride.

[0031] In step S2,a, the mass-volume ratio of mercapto silicone oil with a mercapto content of 8%, vinyl-modified polyvinyl chloride, calcium-zinc stabilizer, and tetrahydrofuran is 7g:10g:0.1g:60mL.

[0032] In step S3, the mass-volume ratio of mercapto-silicone grafted vinyl-modified polyvinyl chloride, mercapto-silicone oil with 8% mercapto content, acrylate-based silicone oil, and tetrahydrofuran is 5g:7g:7g:10mL. The photoinitiator in step S3 is Irgacure 184, the silane coupling agent is KH-570, and the leveling agent is BYK-333.

[0033] To better illustrate the technology and inventiveness of the present invention, the following embodiments and comparative examples are provided.

[0034] Example 1 S1. Preparation of vinyl-modified polyvinyl chloride: a. Add 10g of polyvinyl chloride, 0.2g of calcium-zinc stabilizer (purchased from Shandong Yunxin New Material Technology Co., Ltd.) and 200mL of tetrahydrofuran to a three-necked flask; install a condenser and stir magnetically at 600rpm for 4h in a nitrogen atmosphere at 50℃ oil bath. b. Add 1.6g allyl mercaptan (purchased from Nantong Zhonghe Chemical New Materials Co., Ltd.), mix well, then add 0.05g azobisisobutyronitrile, heat to 65℃, and reflux in the dark for 8 hours; c. After the reaction is complete, cool to room temperature, slowly add the reaction solution to 1L of methanol to precipitate, filter to collect the precipitate, wash with methanol 3 times, and dry under vacuum at 40℃ for 24h to obtain vinyl-modified polyvinyl chloride. Preparation of S2, mercapto-organosilicon-grafted vinyl-modified polyvinyl chloride a. Add 10.5g of mercapto-silicone oil with a mercapto content of 8%, 15g of vinyl-modified polyvinyl chloride, 0.15g of calcium-zinc stabilizer and 90mL of tetrahydrofuran to a three-necked flask; install a condenser and stir magnetically at 600rpm for 4h in a nitrogen atmosphere at 50℃ oil bath. b. After stirring, add 0.03 g of azobisisobutyronitrile, heat to 65°C, and reflux in the dark for 6 h; c. After the reaction is complete, cool to room temperature, slowly add the reaction solution to 1L of methanol to precipitate, filter to collect the precipitate, wash with methanol 3 times, and dry under vacuum at 40℃ for 24h to obtain mercapto-organosilicon-grafted vinyl-modified polyvinyl chloride. S3. Preparation of UV-curable silicone adhesive: 25g of mercaptosilicone-grafted vinyl-modified polyvinyl chloride was dissolved in 50mL of tetrahydrofuran and stirred for 6h. Under light-protected conditions, 35g of mercaptosilicone oil with a mercapto content of 8%, 35g of bis-3-methylpropenyloxypropyltetramethyldisiloxane (CAS No.: 146632-07-7, purchased from Hubei Chengfeng Chemical Co., Ltd.), 3g of Irgacure 184, 1g of KH-570 and 0.1g of BYK-333 were added. The mixture was stirred at 600rpm for 5h at room temperature in the dark to obtain UV-curable silicone adhesive A1.

[0035] Example 2 S1. Preparation of vinyl-modified polyvinyl chloride: a. Add 10g of polyvinyl chloride, 0.2g of calcium-zinc stabilizer (purchased from Shandong Yunxin New Material Technology Co., Ltd.) and 200mL of tetrahydrofuran to a three-necked flask; install a condenser and stir magnetically at 600rpm for 4h in a nitrogen atmosphere at 50℃ oil bath. b. Add 1.6g allyl mercaptan (purchased from Nantong Zhonghe Chemical New Materials Co., Ltd.), mix well, then add 0.05g azobisisobutyronitrile, heat to 65℃, and reflux in the dark for 8 hours; c. After the reaction is complete, cool to room temperature, slowly add the reaction solution to 1L of methanol to precipitate, filter to collect the precipitate, wash with methanol 3 times, and dry under vacuum at 40℃ for 24h to obtain vinyl-modified polyvinyl chloride. Preparation of S2, mercapto-organosilicon-grafted vinyl-modified polyvinyl chloride a. Add 10.5g of mercapto-silicone oil with a mercapto content of 8%, 15g of vinyl-modified polyvinyl chloride, 0.15g of calcium-zinc stabilizer and 90mL of tetrahydrofuran to a three-necked flask; install a condenser and stir magnetically at 600rpm for 4h in a nitrogen atmosphere at 50℃ oil bath. b. After stirring, add 0.03 g of azobisisobutyronitrile, heat to 65°C, and reflux in the dark for 6 h; c. After the reaction is complete, cool to room temperature, slowly add the reaction solution to 1L of methanol to precipitate, filter to collect the precipitate, wash with methanol 3 times, and dry under vacuum at 40℃ for 24h to obtain mercapto-organosilicon-grafted vinyl-modified polyvinyl chloride. S3. Preparation of UV-curable silicone adhesive: 30g of mercaptosilicone-grafted vinyl-modified polyvinyl chloride was dissolved in 60mL of tetrahydrofuran and stirred for 6h. Under light-protected conditions, 30g of mercaptosilicone oil with 8% mercapto content and 30g of bis-3-methylpropenyloxypropyltetramethyldisiloxane were added, followed by 2.8g of Irgacure 184, 0.9g of KH-570 and 0.1g of BYK-333. The mixture was stirred at 600rpm for 5h at room temperature in the dark to obtain UV-curable silicone adhesive A2.

[0036] That is, in step S3, the mass ratio of mercaptosilicone-grafted vinyl-modified polyvinyl chloride, mercaptosilicone oil and bis-3-methylpropenyloxypropyltetramethyldisiloxane is 1:1:1, and the other specific parameters are the same as in Example 1.

[0037] Comparative Example 1 This comparative example is based on Example 1, except that no modification of polyvinyl chloride is performed; that is, the steps are as follows: Preparation of S1, Thiol-based organosilicon-grafted vinyl-modified polyvinyl chloride a. Add 10.5g of mercaptosilicone oil with a mercapto content of 8%, 15g of polyvinyl chloride, 0.15g of calcium-zinc stabilizer and 90mL of tetrahydrofuran to a three-necked flask, install a condenser, and stir magnetically for 4 hours in a nitrogen atmosphere under an oil bath at 50℃. b. After stirring, add 0.03 g of azobisisobutyronitrile, heat to 65°C, and reflux in the dark for 6 h; c. After the reaction is complete, cool to room temperature, slowly add the reaction solution to 1L of methanol to precipitate, filter to collect the precipitate, wash with methanol 3 times, and dry under vacuum at 40℃ for 24h to obtain mercapto-organosilicon-grafted vinyl-modified polyvinyl chloride. S2. Preparation of UV-curable silicone adhesive: 25g of mercaptosilicone-grafted vinyl-modified polyvinyl chloride was dissolved in 50mL of tetrahydrofuran and stirred for 6h. 35g of mercaptosilicone oil with a mercapto content of 8% and 35g of bis-3-methylpropenyloxypropyltetramethyldisiloxane were added under light-protected conditions. Then, 3g of Irgacure 184, 1g of KH-570, and 0.1g of BYK-333 were added. The mixture was stirred at room temperature under light-protected conditions for 5h to obtain UV-curable silicone adhesive D1.

[0038] Comparative Example 2 This comparative example is based on Example 1, except that mercapto silicone oil is not added, i.e., the steps are as follows: S1. Preparation of vinyl-modified polyvinyl chloride: a. Add 10g of polyvinyl chloride, 0.2g of calcium-zinc stabilizer and 200mL of tetrahydrofuran to a three-necked flask, install a condenser, and magnetically stir for 4 hours in a nitrogen atmosphere under an oil bath at 50℃. b. Add 1.6g allyl mercaptan, mix well, then add 0.05g azobisisobutyronitrile, heat to 65℃, and reflux in the dark for 8 hours; c. After the reaction is complete, cool to room temperature, slowly add the reaction solution to 1L of methanol to precipitate, filter to collect the precipitate, wash with methanol 3 times, and dry under vacuum at 40℃ for 24h to obtain vinyl-modified polyvinyl chloride. S2. Preparation of UV-curable silicone adhesive: 25g of vinyl-modified polyvinyl chloride was dissolved in 50mL of tetrahydrofuran and stirred for 6h. 35g of bis-3-methylpropenyloxypropyltetramethyldisiloxane was added under light-protected conditions. Then, 1.88g of Irgacure 184, 0.63g of KH-570, and 0.06g of BYK-333 were added. The mixture was stirred at room temperature under light-protected conditions for 4-6h to obtain UV-curable silicone adhesive D2.

[0039] Comparative Example 3 This comparative example is based on Example 1, except that bis-3-methylpropenyloxypropyltetramethyldisiloxane is not added. The specific steps are as follows: S1. Preparation of vinyl-modified polyvinyl chloride: a. Add 10g of polyvinyl chloride, 0.2g of calcium-zinc stabilizer and 200mL of tetrahydrofuran to a three-necked flask, install a condenser, and magnetically stir for 3-4 hours in a nitrogen atmosphere under an oil bath at 50℃. b. Add 1.6g allyl mercaptan, mix well, then add 0.05g azobisisobutyronitrile, heat to 65℃, and reflux in the dark for 8 hours; c. After the reaction is complete, cool to room temperature, slowly add to 1L of methanol to precipitate, filter to collect the precipitate, wash with methanol 3 times, and dry under vacuum at 40℃ for 24h to obtain vinyl-modified polyvinyl chloride. Preparation of S2, mercapto-organosilicon-grafted vinyl-modified polyvinyl chloride a. Add 10.5g of mercapto-silicone oil with a mercapto content of 8%, 15g of vinyl-modified polyvinyl chloride, 0.15g of calcium-zinc stabilizer and 90mL of tetrahydrofuran to a three-necked flask, install a condenser, and stir magnetically in a nitrogen atmosphere at 50℃ oil bath for 3-4 hours. b. After stirring, add 0.03 g of azobisisobutyronitrile, heat to 65°C, and reflux in the dark for 6 h; c. After the reaction is complete, cool to room temperature, slowly add to 1L of methanol to precipitate, filter to collect the precipitate, wash with methanol 3 times, and dry under vacuum at 40℃ for 24h to obtain mercapto-organosilicon-grafted vinyl-modified polyvinyl chloride. S3. Preparation of UV-curable silicone adhesive: 25g of mercaptosilicone-grafted vinyl-modified polyvinyl chloride was dissolved in 50mL of tetrahydrofuran and stirred for 6h. 35g of mercaptosilicone oil with a mercapto content of 8% was added under light-protected conditions. Then, 1.88g of Irgacure 184, 0.63g of KH-570, and 0.06g of BYK-333 were added. The mixture was stirred at room temperature under light-protected conditions for 4-6h to obtain UV-curable silicone adhesive D3.

[0040] After preparation, the UV-curable silicone adhesives prepared in Examples 1, 2, and Comparative Examples 1-3 were applied to a clean aluminum substrate using a wire bar coater to obtain a wet film with a thickness of 100-200 μm. The wet film was placed on a 50°C heating plate for 5 min to allow most of the solvent to evaporate. The sample was then immediately placed under a 365 nm UV light source with a light intensity of 100 mW / cm² and an irradiation time of 90 s. After curing, the corresponding adhesive films A1, A2, D1, D2, and D3 were obtained.

[0041] Test Example 1 The UV-curable silicone adhesive films prepared above were tested for initial tack according to GB / 4852 2002 (Method A: Inclined Rolling Ball Method) and holding power according to GB / 4851 1998. Test pieces were prepared according to GB / T2790 1995 "Test Method for 180° Peel Strength of Adhesives" to test the peel strength of the adhesive at room temperature, 100°C, and -60°C. The preparation methods for the room temperature, 100°C, and -60°C peel strength test pieces were as follows: after adhering the adhesive to an aluminum foil backing, the films were placed at room temperature (25°C), 100°C, and -60°C for 30 days, respectively, and then subjected to 180° peel tests. After the 100°C peel strength test, the amount of residual adhesive on the aluminum foil backing was measured by weighing. The amount of residual adhesive was determined by the formula... Calculations. The initial tack, holding power, peel strength at 180°C, peel strength at 100°C, and peel strength at -60°C for UV-cured silicone adhesive films A1, A2, D1, D2, and D3 are shown in Table 1.

[0042] Table 1. Initial tack, holding power, peel strength at 180°C, peel strength at 100°C, and peel strength at -60°C for UV-curable silicone adhesive films A1, A2, D1, D2, and D3.

[0043] It can be seen that film A1 exhibits the best initial tack, holding power, and peel strength at 180°C at room temperature; at 100°C and -60°C, its peel strength at 180°C decreases by only 5.6% and 10.3% compared to room temperature, respectively, and the residual adhesive amount after peeling at 100°C is only 65mg, indicating that it has good adhesion and resistance to high and low temperatures.

[0044] Compared with film A1, the performance of film A2 prepared in Example 2 is slightly reduced, but it still maintains a high performance level, indicating that the UV-curable silicone adhesive prepared by the present invention has good adhesion and high and low temperature resistance, but the formulation ratio will affect the performance.

[0045] Adhesive films D1, D2, and D3 exhibited poor adhesion and resistance to high and low temperatures. Among them, adhesive film D1 had the lowest adhesion and peel strength, and the largest amount of residual adhesive after peeling at 100°C. Its initial tack, peel strength at room temperature (180°C), peel strength at 100°C, and peel strength at -60°C decreased by 58.3%, 57.4%, 76.4%, and 82.0% respectively compared to adhesive film A1, while the amount of residual adhesive after peeling at 100°C increased by 95.4%. Its holding power was only 2.5h, indicating that the unmodified PVC has poor compatibility with organosilicon and cannot form an effective cross-linking network. The performance of adhesive films D2 and D3 was significantly lower than that of adhesive films A1 and A2, indicating that mercapto-based organosilicon and acrylate-based organosilicon are key components for network construction and flexibility control in adhesives. The rigid-flexible cross-linking network formed by these two components with vinyl-modified PVC is key to good cohesion, high / low temperature stability, flexibility, and adhesion.

[0046] Test Example 2 Curing time is an important parameter for measuring the application efficiency, final performance and applicability of adhesives. Therefore, this invention measures the curing time of UV-curable silicone adhesives by referring to the method in GB / T 14072-2006.

[0047] Figure 1 The curing time diagram of the UV-curable silicone adhesive provided by the present invention shows that the UV-curable silicone adhesive D1 prepared in Comparative Example 1 exhibits the longest curing time, at 120s; while the UV-curable silicone adhesive A1 prepared in Example 1 exhibits the shortest curing time, at 65s. This indicates that the UV-curable silicone adhesive prepared by the present invention has excellent rapid photocuring characteristics, and vinyl modification of polyvinyl chloride can effectively improve the compatibility between polyvinyl chloride and silicone materials, significantly improving the curing speed of the adhesive. The UV-curable silicone adhesive A2, which is also a complete component like A1, has a slightly longer curing time than A1, but is still significantly lower than the adhesives prepared in each comparative example.

[0048] The curing times of UV-curable silicone adhesives D2 and D3 are longer than those of UV-curable silicone adhesives A1 and A2, but significantly shorter than those of D1, indicating that vinyl-modified polyvinyl chloride provides a high density of reactive double bond sites. Meanwhile, a highly efficient thiol-ene click reaction can occur between mercapto silicone oil and acrylate silicone oil under UV initiation.

[0049] Test Example 3 The volume change rate of UV-cured silicone adhesives was tested in accordance with ISO 3521-1997 "Determination of total volume shrinkage of unsaturated polyester and epoxy resins".

[0050] Figure 2The volume shrinkage rate diagram of the UV-curable silicone adhesives provided by this invention shows that UV-curable silicone adhesive A1 exhibits the lowest volume change rate at 1.8%. The volume change rate of UV-curable silicone adhesive A2 is slightly higher than that of A1, but significantly lower than that of the comparative examples. The volume change rates of UV-curable silicone adhesives D3, D2, and D1 increase sequentially, with D1 having the highest rate at 5.5%. The results indicate that the UV-curable silicone adhesives prepared by this invention can effectively maintain volume stability and have a low shrinkage rate during curing. This is because the rigid vinyl-modified polyvinyl chloride segments act as a skeleton to inhibit shrinkage, while the cross-linked network formed by the flexible mercapto silicone oil and acrylate silicone oil effectively buffers and disperses curing stress.

[0051] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A UV-curable silicone adhesive, characterized in that, This includes mercapto-based silicone materials, acrylate-based silicone materials, and vinyl-modified polyvinyl chloride.

2. The UV-curable silicone adhesive as described in claim 1, characterized in that, The mercapto-based organosilicon material is mercapto-based silicone oil with a mercapto content of 8%, and the acrylate-based organosilicon material is bis-3-methylpropenyloxypropyltetramethyldisiloxane.

3. The UV-curable silicone adhesive as described in claim 1, characterized in that, The mass ratio of the mercapto-based organosilicon material, the acrylate-based organosilicon material, and the vinyl-modified polyvinyl chloride is 1:(1-3):(1-2.5).

4. The UV-curable silicone adhesive as described in claim 3, characterized in that, The mass ratio of the mercapto-based silicone material, the acrylate-based silicone material, and the vinyl-modified polyvinyl chloride is 1:3:2.

3.

5. A method for preparing a UV-curable silicone adhesive, characterized in that, Includes the following steps: S1. Preparation of vinyl-modified polyvinyl chloride; S2, Preparation of mercapto-organosilicon-grafted vinyl-modified polyvinyl chloride; S3. Preparation of UV-curable silicone adhesive: Thiol-based organosilicon grafted with vinyl-modified polyvinyl chloride and tetrahydrofuran were mixed and stirred for 6 hours. Thiol-based silicone oil with a thiol content of 8% and bis-3-methylpropenyloxypropyltetramethyldisiloxane were added, followed by photoinitiator with a total solid mass of 3%, silane coupling agent with a total solid mass of 1%, and leveling agent with a total solid mass of 0.1%. The mixture was stirred at 500-600 rpm in the dark at room temperature for 4-6 hours to obtain UV-curable organosilicon adhesive.

6. The method for preparing the UV-curable silicone adhesive as described in claim 5, characterized in that, Step S1 includes the following steps: a. Mix polyvinyl chloride, calcium zinc stabilizer and tetrahydrofuran in a three-necked flask at a mass-to-volume ratio of 5g:0.1g:100mL, install a condenser, and magnetically stir at 500-600rpm for 3-4 hours in a nitrogen atmosphere under an oil bath at 50℃. b. Add 15-20% of allyl mercaptan by weight of polyvinyl chloride, mix well, and then add azobisisobutyronitrile. The mass ratio of allyl mercaptan to azobisisobutyronitrile is (30-40):

1. Heat to 65℃ and reflux in the dark for 8 hours. c. After the reaction is complete, cool to room temperature, slowly add the reaction solution to methanol to precipitate, filter to collect the precipitate, wash with methanol 3 times, and dry under vacuum at 40°C for 24 hours to obtain vinyl-modified polyvinyl chloride.

7. The method for preparing the UV-curable silicone adhesive as described in claim 5, characterized in that, Step S2 includes the following steps: a. Add mercapto-silicone oil with a mercapto content of 8%, vinyl-modified polyvinyl chloride, calcium-zinc stabilizer and tetrahydrofuran to a three-necked flask; install a condenser and magnetically stir at 500-600 rpm for 3-4 hours in a nitrogen atmosphere under an oil bath at 50°C. b. After stirring, add 0.2% (by weight) of azobisisobutyronitrile to mercaptosilicone oil, heat to 65°C, and reflux in the dark for 6 hours; c. After the reaction is complete, cool to room temperature, slowly add the reaction solution to methanol to precipitate, filter to collect the precipitate, wash with methanol 3 times, and vacuum dry at 40℃ for 24h to obtain mercapto-organosilicon-grafted vinyl-modified polyvinyl chloride.

8. The method for preparing the UV-curable silicone adhesive as described in claim 7, characterized in that, In step S2, the mass-volume ratio of the 8% thiol content mercapto silicone oil, vinyl-modified polyvinyl chloride, calcium-zinc stabilizer, and tetrahydrofuran is 7g:10g:0.1g:60mL.

9. The method for preparing the UV-curable silicone adhesive as described in claim 5, characterized in that, In step S3, the mass-volume ratio of the mercapto-silicone grafted vinyl-modified polyvinyl chloride, the mercapto-silicone oil with a mercapto content of 8%, the acrylate-based silicone oil, and the tetrahydrofuran is 5g:7g:7g:10mL. The photoinitiator is Irgacure 184, the silane coupling agent is KH-570, and the leveling agent is BYK-333.

10. The use of the UV-curable silicone adhesive as described in any one of claims 1-4 in the preparation of pressure-sensitive adhesives, sealant adhesives, laminating adhesives and potting compounds.

Images