Silica gel belt with good viscosity and preparation method thereof

Abstract

The invention relates to the field of high polymer materials and adhesion, and discloses a silica gel belt with good viscosity and a preparation method thereof, and the silica gel belt comprises a back base layer, an interface grafting activation layer, a main pressure-sensitive adhesive layer and a release film from bottom to top. Through the design of a double-layer structure, a component with double functional groups is introduced into an interface layer, so that chemical bridging between silica gel and an upper-layer adhesive is realized; the main bonding layer adopts a multi-phase polymer system, so that the bonding performance and the structural stability are enhanced. The interface layer contains acryloyloxypropyltriethoxysilane, an isocyanate-terminated polyester polymer and other components, and a grafting layer is formed under the irradiation of ultraviolet light; the main bonding layer contains acrylic acid-polyether copolymer, amino silane modified polyurethane and other components, and cross-linking setting is achieved through thermocuring. Through an interface synergistic reaction mechanism, structural interconnection between material layers is realized, and the bonding force and the structural adaptability of the silica gel belt are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of polymer materials and adhesive technology, and in particular to a silicone tape with good adhesion and its preparation method. Background Technology

[0002] Existing silicone tape products often suffer from insufficient adhesion, especially in bonded structures. Due to the difference in polarity and chemical inertness, the silicone substrate and pressure-sensitive adhesive layer are prone to weak interfaces, unstable adhesion, and easy delamination. This is mainly because traditional preparation methods fail to effectively construct a chemically continuous transition region, leaving the layers to rely solely on physical adsorption or mechanical adhesion to maintain connection. This makes it difficult to maintain structural integrity and adhesive durability under long-term use or external forces. Furthermore, when existing pressure-sensitive adhesive systems are bonded to low-polarity substrates (such as silicone), poor interfacial wettability and a lack of reaction sites often prevent the adhesive layer from fully utilizing its bonding performance, thus limiting the overall performance of the material system.

[0003] Therefore, existing technologies still have significant shortcomings in interface processing and multilayer adhesive structure design, and there is an urgent need for a new material solution that can establish a stable chemical connection between silicone and the adhesive layer, improve adhesion and structural synergy. Summary of the Invention

[0004] The purpose of this invention is to provide a silicone tape with good adhesion and its preparation method, which solves the problems of poor adhesion and interface incompatibility between the silicone substrate and the pressure-sensitive adhesive layer.

[0005] To achieve the above objectives, the present invention provides the following technical solution: The first aspect of the present invention provides a silicone tape with good adhesion, comprising, from bottom to top, a backing layer, an interface grafting activation layer, a main pressure-sensitive adhesive layer, and a release film; The grafted activation layer comprises the following components by weight: Acryloyloxypropyltriethoxysilane 3-8 parts; 5-10 parts of isocyanate-terminated polyester block polymer; 30-60 parts of ethyl acetate; Cyclohexanone 10-25 parts; Photoinitiator 0.5–2 parts; The main pressure-sensitive adhesive layer comprises the following components by weight: 40-60 parts of acrylic acid-polyether block copolymer; 20-30 parts of aminosilane-modified polyurethane prepolymer; 5-15 parts of liquid SEBS elastomer; 3-5 parts of sulfonated phenolic resin; 0.5–1.5 parts of HDI-type isocyanate crosslinking agent; 10-20 parts of methyl ethyl ketone (MEK).

[0006] This invention employs a two-layer structure for differentiated design in terms of material configuration. The interface grafting activation layer introduces components with bifunctional reactive groups, enabling it to both chemically bond with the underlying silicone and provide further reaction sites for the upper pressure-sensitive adhesive system. Specifically, acryloyloxypropyltriethoxysilane can undergo a condensation reaction between its triethoxy group and the silanol groups on the silicone surface to form a stable silicon-oxygen bond; while its acryloyl group does not participate in the underlying reaction and is reserved for subsequent free radical reaction bonding.

[0007] The isocyanate-terminated polyester block polymer provides an intermediate component with extended segments and isocyanate-terminated structure in this layer. This component possesses both flexibility and the ability to participate in subsequent polymerization and crosslinking reactions, giving the interfacial layer a bidirectional functional basis from its initial formation. The grafting solution uses a solvent system of ethyl acetate and cyclohexanone, which adjusts the solution polarity and evaporation rate, facilitating uniform spreading and reaction residence on the low-polarity silica surface. The addition of a photoinitiator initiates free radical polymerization under UV conditions, completing the grafting and fixation process of unsaturated groups on the surface.

[0008] The design mechanism of this interface activation layer is to stabilize the reactive functional groups at the interface, prevent them from becoming blocked or diffused during the pretreatment stage, and control their reaction depth and position through a photoinitiation mechanism, thereby achieving a "reaction bridge" from silicone to the upper layer at the molecular scale.

[0009] In the main pressure-sensitive adhesive layer, the components together constitute a multiphase system with certain polarity, flexibility, and reactivity. The acrylic-polyether block copolymer contains hydrophilic polyether segments, which can adjust the interfacial contact properties and provide polymerizable segments for grafting or crosslinking reactions with residual double bonds in the interfacial layer. The aminosilane-modified polyurethane prepolymer serves as the structural backbone carrier, participating in multi-site reactions with the assistance of its amino and hydroxyl functional groups, further enhancing structural connectivity.

[0010] Liquid SEBS elastomers introduce non-polar hydrophobic blocks into their structure, improving the compliance and stress regulation capabilities of the adhesive layer under micro-deformation. Meanwhile, sulfonated phenolic resin, as a low-migration tackifying phase, has a polar multi-site structure and exhibits a certain degree of intermolecular interaction tendency with polyether and polyurethane components, and can participate in local entanglement or indirect synergy in the pre-crosslinking stage.

[0011] HDI-type isocyanate crosslinking agents provide the final thermosetting crosslinking conditions, forming a covalent crosslinking network with the upper polyurethane layer and the lower residual functional groups, enabling the upper structure to be spatially fixed in the later stage of formation and establishing a stable multi-point structural support.

[0012] The technical concept of this invention lies in constructing an interface layer with chemical continuity, enabling a synergistic reaction mechanism between the functional components of the main pressure-sensitive adhesive layer and the underlying silicone, thereby achieving structural interconnection between material layers on a macroscopic level and reducing the formation of molecular chain breaks and inert regions at the microscopic level. This dual-layer design gives the silicone tape excellent material compatibility and configurational flexibility, providing a foundation for its overall structural stability and adhesive performance.

[0013] Preferably, the acryloyloxypropyltriethoxysilane is selected from 3-(acryloyloxy)propyltriethoxysilane, a commercially available conventional silane coupling agent with the structural formula CH2=CHCOO(CH2)3Si(OC2H5)3, which can be obtained by esterification of acrylic acid with 3-hydroxypropyltriethoxysilane.

[0014] Preferably, the method for preparing the isocyanate-terminated polyester block polymer includes the following steps: (1) Under an inert atmosphere, add poly(hexanediol adipate) or hexanediol adipate triblock polyester into the reactor and heat to 80-100°C. (2) Under stirring conditions, slowly add an excess of isocyanate compound (such as hexamethylene diisocyanate HDI) to control the molar ratio of the reactants so that the ends of the polyester chain are capped by isocyanate groups. (3) After the reaction continues for 2 to 4 hours, the temperature is lowered, and the byproducts are removed by filtration to obtain a polyester block polymer with isocyanate-terminated structure. The average number-average molecular weight of this polymer is controlled at 2000 to 5000 g / mol, and the terminal functionality is about 2.

[0015] The polymer is a pale yellow transparent liquid at room temperature, with a certain viscosity and reactivity. It can undergo addition crosslinking with structures containing hydroxyl or amine groups, and is suitable as a reactive bridge in surface-activated systems.

[0016] Preferably, the ethyl acetate is selected from industrial grade or analytical grade ethyl acetate, and is a conventional medium polar solvent.

[0017] Preferably, the cyclohexanone is selected from industrial grade or analytical grade cyclohexanone, which is a moderately polar ketone solvent.

[0018] Preferably, the photoinitiator is selected from α-hydroxy ketones or phenyl ketones, specifically including: 2-hydroxy-2-methylpropanone (Darocur 1173), 1-hydroxycyclohexylphenyl ketone (Irgacure 184), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (Irgacure 819), etc. These initiators can absorb ultraviolet light and undergo degradation in the wavelength range of 300–400 nm, generating free radicals, which in turn initiate the polymerization reaction of acrylic unsaturated groups.

[0019] Preferably, the preparation method of the acrylic-polyether block copolymer includes the following steps: (1) Add hydrophilic polyether polyol (such as polyethylene glycol or polypropylene glycol) and acrylic monomer (such as acrylic acid, hydroxyethyl methacrylate) to the reactor at a set molar ratio, and carry out free radical polymerization reaction at 70-90°C using peroxide or AIBN initiator; (2) During the polymerization process, an appropriate amount of chain transfer agent is introduced to control the molecular weight. After the reaction is completed, the residual monomers and oligomers are removed to obtain an acrylic acid-polyether block copolymer with a number average molecular weight of 5000-10000 g / mol. (3) The hydrophilic polyether segments in the obtained polymer structure are 20-35 wt%, which have both flexibility and polarity, and are conducive to interfacial wetting and crosslinking activity.

[0020] The polyether segments are typically polyethylene glycol or polypropylene glycol, possessing a degree of flexibility and polarity, which enhances the interfacial wettability and substrate adaptability of the pressure-sensitive adhesive layer. The polyether segments and acrylic blocks form a relatively flexible-rigid structural combination, providing polar interaction sites while preserving the spatial mobility of the segments. This facilitates further chemical coupling with functional groups in the interfacial grafted layer, thereby enhancing the overall structural synergy and stability of the system.

[0021] Preferably, the preparation method of the aminosilane-modified polyurethane prepolymer includes the following steps: (1) Using hydroxyl-terminated polyethers or polyesters as soft segment main chains (such as PTMG, PEG, etc.), react with isocyanate components (such as TDI, HDI) under anhydrous conditions to form a prepolymer structure, and control the NCO content in the reaction to be between 1% and 2%. (2) Then, an end-capping agent with aminosilane functional group (such as 3-aminopropyltriethoxysilane, 3-aminopropyldimethylethoxysilane) is introduced to end-cap the polyurethane main chain so that the ends of the polyurethane main chain have the ability to be hydrolyzed or further crosslinked. (3) This type of prepolymer is a pale yellow liquid or semi-solid with moderate viscosity and good miscibility with polar components.

[0022] By introducing silane functional groups, the prepolymer can participate in subsequent condensation or co-crosslink with hydroxyl components, thereby improving structural compatibility and chemical bond connectivity.

[0023] Preferably, the liquid SEBS elastomer is a styrene-ethylene / butene-styrene block copolymer with a styrene content of 20-30 wt%. In this type of elastomer structure, the styrene block provides certain physical crosslinking points, enhancing the thermal stability and resilience of the adhesive layer, while the intermediate ethylene-butene flexible segment imparts good flexibility and deformation response to the system. In the liquid state, this copolymer exhibits low viscosity and good dispersibility, facilitating its co-distribution with other polar polymers in the adhesive layer, thereby maintaining interlayer processability while enhancing interfacial adhesion and structural consistency.

[0024] Preferably, the sulfonated phenolic resin is selected from the product of sulfonation modification after condensation of phenol and formaldehyde under acid catalysis. It has certain polarity and crosslinking sites, and its molecular structure contains sulfonic acid groups and phenolic hydroxyl groups, which is beneficial for physical entanglement and hydrogen bonding with the pressure-sensitive adhesive main system.

[0025] Preferably, the HDI-type isocyanate crosslinking agent is selected from hexamethylene diisocyanate (HDI) and its trimer, or biuret-type trifunctional crosslinking agents. This type of crosslinking agent exhibits good flexibility and reaction control; the terminal isocyanate groups can undergo addition reactions with amino and hydroxyl active groups to construct a spatial crosslinked structure, enhancing the stability and mechanical consistency of the cured adhesive layer.

[0026] Preferably, the butanone is selected from industrial grade or analytical grade methyl ethyl ketone (MEK), which is a conventional moderately polar ketone solvent.

[0027] Preferably, the silicone substrate layer is made of silicone elastomer with a Shore A hardness of 25-40 and a thickness of 0.1-0.5 mm.

[0028] The silicone elastomer can be vinyl-terminated polydimethylsiloxane or a cross-linked silicone rubber formed by blending it with methylhydrosiloxane. It is then thermo-cured by adding an appropriate amount of peroxide or platinum catalyst to form a substrate layer with certain elasticity and dimensional stability. Within the aforementioned hardness and thickness range, both the flexible bonding capability of the substrate and sufficient mechanical support are ensured, providing the necessary structural foundation for subsequent interface treatment and adhesive layer application.

[0029] Preferably, the coating amount of the interface grafting activation layer is 5-20 g / m². 2 Furthermore, after being irradiated with ultraviolet light at a wavelength of 365nm for 20–60 seconds, a grafted structure is formed.

[0030] Within this coating amount range, a uniform and continuous active coating can be formed on the silicone surface, ensuring sufficient functional group coverage density while avoiding uneven curing or solvent residue caused by excessive thickness. UV irradiation activates the initiator decomposition, triggering the polymerization reaction of unsaturated bonds in the coating, causing grafted molecular chains to directionally crosslink on the silicone surface to form a stable interface layer. This treatment method achieves adjustable photo-controlled reaction depth and spatial distribution, facilitating the construction of transition regions with interfacial reaction functions.

[0031] Preferably, the dry film thickness of the main pressure-sensitive adhesive layer is 30–80 μm.

[0032] The second aspect of this invention provides a method for preparing the adhesive silicone tape described in the first aspect, comprising the following steps: 1) Preparation of backing silicone sheet: The silicone elastomer raw materials are uniformly mixed to ensure consistent distribution of fillers, crosslinking agents, and other components within the system. Subsequently, a sheet of uniform thickness is obtained through calendering and then crosslinked through hot vulcanization to form a silicone substrate layer with certain strength and elasticity. This step ensures the physical properties and surface treatment stability of the substrate, providing a reaction platform for subsequent grafting reactions. The resulting silicone sheet thickness is controlled between 0.1 and 0.5 mm, which is beneficial for the performance of the adhesive layer and the overall material flexibility.

[0033] 2) Formation of the interface graft layer: The prepared interface grafting activating solution is uniformly coated onto one side of the silicone sheet, ensuring a continuous and uniform coating. After moderate drying to remove the solvent, it is irradiated with ultraviolet light at a wavelength of 365 nm to excite the photoinitiator to generate free radicals, guiding the polymerization of unsaturated functional groups in the system to form a cross-linked grafted structure. This step constructs a reactive interface layer on the silicone surface, which facilitates subsequent chemical bonding with the main pressure-sensitive adhesive layer. Preferably, the ultraviolet irradiation step uses an energy density of 0.5–2.0 mW / cm². 2 To control the reaction rate and grafting depth, and to avoid surface ablation or insufficient reaction.

[0034] 3) Form the main pressure-sensitive adhesive layer and apply a film: The components required for the main pressure-sensitive adhesive layer are thoroughly mixed according to the formulation requirements to form a uniformly dispersed adhesive system, which is then coated onto the surface of the grafted interface layer. A cross-linking reaction occurs within the adhesive layer through thermosetting, forming an adhesive layer with a stable structure. Preferably, this curing process is carried out at 80–90°C for 10–20 minutes to ensure that the active groups in the system fully react and form a uniformly structured adhesive film. Finally, a release film is laminated onto the adhesive layer surface to obtain the finished silicone tape.

[0035] Through the above steps, a multifunctional adhesive structure with chemical transition interfaces is constructed layer by layer. Through the co-design of formulation and process, the interface compatibility and structural coherence between each layer are unified, providing process assurance for the formation of silicone tape with good adhesion.

[0036] In summary, the present invention has at least one of the following beneficial technical effects: 1. This invention introduces a grafting activation layer to construct an intermediate structure containing reactive functional groups on the surface of silicone, enabling it to covalently bond with the upper pressure-sensitive adhesive layer. This significantly improves the delamination problem caused by the polarity difference between traditional silicone and pressure-sensitive adhesive, achieving stable chemical bridging of the interface.

[0037] 2. This invention introduces a multiphase polymer structure into the main pressure-sensitive adhesive layer, combining polyether, polyurethane and elastomer components, which effectively adjusts the flexibility and compliance of the material. During the bonding process, it can well fit curved or irregular substrates, and is suitable for bonding needs under complex surface conditions.

[0038] 3. The interface grafting layer and adhesive layer of this invention achieve chemical continuity through functional group design, which avoids the formation of reaction blind zones at the molecular level, helps to build structural integrity and long-term adhesive performance, and reduces performance degradation caused by interface incompatibility.

[0039] 4. By introducing a deformation-responsive SEBS elastomer and a polymer structure that can participate in multi-site reactions, this invention can buffer interfacial stress concentration under mechanical action, maintain the stability and dynamic adaptability of the adhesive layer, and is suitable for long-term use in variable environments.

[0040] 5. The overall structural design of the material in this invention transitions step by step from the silicone substrate and the interface activation layer to the pressure-sensitive adhesive layer, forming a multi-dimensional adhesive network that combines chemical and physical processes. This not only improves the bonding strength but also enhances the processing stability and interlayer structural synergy of the material, providing a technical path for the development of high-performance adhesive materials. Detailed Implementation

[0041] The present application will be further described in detail below with reference to the embodiments.

[0042] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0043] Example 1: This invention provides a method for preparing a silicone tape with good adhesion, comprising the following steps: 1) Preparation of back-based silicone sheet A silicone elastomer material with a Shore A hardness of 32 was selected and mixed uniformly using a two-roll mill. The mixture was then calendered to obtain a silicone sheet with a thickness of 0.3 mm. The resulting sheet was then subjected to heat vulcanization at 160℃ for 10 minutes to obtain a backing layer with good mechanical properties and flatness.

[0044] 2) Prepare and coat the interface grafting activation solution 5.5 parts of acryloyloxypropyltriethoxysilane, 7.5 parts of isocyanate-terminated polyester block polymer (Mn approximately 3500 g / mol, end-capped as –NCO), 45 parts of ethyl acetate, 17.5 parts of cyclohexanone, and 1.0 part of photoinitiator (Irgacure 1173) were added to a mixing container and magnetically stirred at room temperature for 15 minutes to ensure complete dissolution and homogeneity, forming a transparent homogeneous solution.

[0045] The solution was uniformly coated onto one side of the silicone sheet using a wire rod method, with the coating amount controlled at 12 g / m². 2 Dry under 60℃ hot air for 3 minutes to remove solvent residue. Then irradiate under a 365nm ultraviolet light source for 40 seconds, with the irradiation energy density controlled at 1.0mW / cm². 2 This causes the surface to form a grafted structure.

[0046] 3) Apply the main pressure-sensitive adhesive layer and cure. 50 parts of acrylic-polyether block copolymer (hydrophilic polyether segments account for about 30 wt%, Mn≈8000 g / mol), 25 parts of aminosilane modified polyurethane prepolymer, 10 parts of liquid SEBS elastomer (styrene content about 25 wt%), 4 parts of sulfonated phenolic resin, 1.0 part of HDI isocyanate crosslinking agent, and 15 parts of methyl ethyl ketone were sequentially added to a high-speed dispersion device and stirred evenly at 1200 rpm for 20 minutes to obtain the coating slurry.

[0047] The obtained slurry was applied to the surface of the grafted layer by scraping, and the dry film thickness was controlled to be 55 μm. Then it was placed in an 85℃ constant temperature oven for curing for 15 minutes, and finally a PET release film was laminated on it. After cooling, it was rolled up to obtain the finished silicone tape.

[0048] Example 2: This invention provides a method for preparing a silicone tape with good adhesion, comprising the following steps: 1) Preparation of back-based silicone sheet Using an organosilicon elastomer with a Shore A hardness of 25 and a thickness of 0.1 mm, the mixture is calendered after compounding and then hot-pressed at 155°C for 8 minutes to form a soft and highly adaptable silicone substrate.

[0049] 2) Prepare and coat the interface grafting activation solution Weigh out 3 parts of acryloyloxypropyltriethoxysilane, 5 parts of isocyanate-terminated polyester block polymer with approximately 2000 g / mol of Mn, 30 parts of ethyl acetate, 10 parts of cyclohexanone, and 0.5 parts of photoinitiator, and mix them evenly under ultrasonic stirring.

[0050] The solution was applied to the surface of the silicone sheet by spraying, with the spraying amount controlled at 5 g / m². 2 Dry at 50℃ for 2 minutes, then irradiate with 365nm wavelength ultraviolet light for 20 seconds, with the light intensity controlled at 0.5mW / cm². 2 .

[0051] 3) Apply the main pressure-sensitive adhesive layer and cure. Take 40 parts of acrylic acid-polyether block copolymer (hydrophilic segments approximately 20wt%, Mn≈5000g / mol), 20 parts of aminosilane modified polyurethane prepolymer, 5 parts of liquid SEBS elastomer, 3 parts of sulfonated phenolic resin, 0.5 parts of HDI crosslinking agent, and 10 parts of methyl ethyl ketone, and magnetically stir at room temperature for 30 minutes to obtain a stable slurry.

[0052] The slurry was evenly coated onto the surface of the grafted layer, and the dry film thickness was controlled to be 30 μm. It was then cured at 80°C for 10 minutes, and finally a low-viscosity LDPE release film was laminated to complete the preparation.

[0053] Example 3: This invention provides a method for preparing a silicone tape with good adhesion, comprising the following steps: 1) Preparation of back-based silicone sheet A high-modulus silicone elastomer with a Shore A hardness of 40 is selected. It is mixed and calendered on two rollers to control the thickness to 0.5 mm. Then it is hot-cured at 170℃ for 12 minutes to form a silicone backing layer with excellent mechanical strength.

[0054] 2) Prepare and coat the interface grafting activation solution Eight parts of acryloyloxypropyltriethoxysilane, ten parts of isocyanate-terminated polyester block polymer (Mn approximately 5000 g / mol), 60 parts of ethyl acetate, 25 parts of cyclohexanone, and two parts of a high-efficiency photoinitiator were added to a mixing reactor and stirred at room temperature for 20 minutes under nitrogen protection to ensure thorough homogenization.

[0055] The solution was evenly applied to the surface of the silicone sheet using a scraping method, with a coating amount of 20 g / m². 2 The drying conditions were 70℃ for 4 minutes. Then, it was irradiated with 365nm ultraviolet light for 60 seconds, with a UV energy density of 2.0mW / cm². 2 To form a high-density grafting interface.

[0056] 3) Apply the main pressure-sensitive adhesive layer and cure. A high-viscosity coating liquid was prepared by mixing 60 parts of acrylic-polyether block copolymer (35wt% hydrophilic segments, approximately 10000g / mol Mn), 30 parts of aminosilane-modified polyurethane prepolymer, 15 parts of SEBS elastomer (30wt% styrene content), 5 parts of sulfonated phenolic resin, 1.5 parts of HDI crosslinking agent, and 20 parts of methyl ethyl ketone in a high-speed shear emulsifier and stirring (2000rpm, 15 minutes).

[0057] A high-precision coating device was used to apply the coating, controlling the dry film thickness to 80 μm. The film was then cured in a 90℃ oven for 20 minutes. After cooling, an antistatic PET release film was laminated to complete the preparation of the adhesive silicone tape.

[0058] Comparative Example 1: Compared with Example 1, the difference is that the isocyanate-terminated polyester block polymer is omitted in the interface grafting activation layer, while the rest are the same.

[0059] Comparative Example 2: Compared with Example 1, the difference is that the amount of liquid SEBS elastomer in the main pressure-sensitive adhesive layer is 2 parts, while the rest are the same.

[0060] Comparative Example 3: Compared with Example 1, the difference is that the HDI-type isocyanate crosslinking agent is omitted in the main pressure-sensitive adhesive layer, while the rest are the same.

[0061] Comparative Example 4: Compared with Example 1, the difference is that the ultraviolet irradiation step of the interface grafting activation layer is omitted, and no grafting structure is formed; otherwise, they are the same.

[0062] Comparative Example 5: Compared with Example 1, the difference is that the amount of acrylic-polyether block copolymer in the main pressure-sensitive adhesive layer is 65 parts, while the rest are the same.

[0063] Comparative Example 6: Compared with Example 1, the difference is that sulfonated phenolic resin is omitted in the main pressure-sensitive adhesive layer, which destroys the tackifying and network synergistic structure; otherwise, they are the same.

[0064] Test Example 1: This experiment was used to test the 180° peel strength of the samples prepared in Example 1 and Comparative Examples 1, 4 and 6 on a standard substrate to evaluate the overall adhesion performance of the adhesive structure.

[0065] The experimental steps are as follows: 1. Sample preparation: Cut each silicone tape sample to a standard size of 25mm wide and 100mm long, ensuring that the adhesive layer, substrate, and release film are complete and consistent. Remove the release film before use.

[0066] 2. Adhesion process: The test sample was attached to a 0.5mm thick PVC board (the surface was pre-cleaned and wiped clean with ethanol). A 2kg standard roller was used to roll the sample back and forth once each to ensure uniform adhesion. After bonding, the sample was left to stand for 30 minutes.

[0067] 3. Test equipment and setup: The peel strength test was conducted using an electronic peel strength tester (tensile force range 100N, accuracy ±0.01N) at a 180° angle and a rate of 300mm / min. The peel length was not less than 75mm.

[0068] 4. Data Recording: Record the peel force variation curve throughout the entire peeling process, and take the average value of the stable section as the peel strength of the sample, in N / 25mm.

[0069] Each sample group was tested at least 3 times, and the average value was taken as the final result.

[0070] The experimental results are shown in Table 1: Table 1. Peel strength test results (180° peel) of silicone tape samples with different formulations. Sample number Average peel strength (N / 25mm) Test 1 Test 2 Test 3 Example 1 5.82 5.91 5.76 5.8 Comparative Example 1 2.47 2.39 2.51 2.52 Comparative Example 4 1.93 2.01 1.85 1.94 Comparative Example 6 3.14 3.06 3.21 3.16 The results of this experiment show that when the formulation does not include end-capped isocyanate-type polyester polymers or undergoes UV-induced grafting treatment, the adhesion between the tape and the silicone substrate decreases significantly. In contrast, after constructing the interfacial grafting structure, a covalent chemical anchoring structure can be formed, achieving effective bridging between the organic pressure-sensitive adhesive system and the low surface energy silicone substrate, significantly improving the interlayer bonding strength. This stable interfacial layer not only possesses good initial adhesion but also enhances the long-term adhesion stability of the overall structure.

[0071] Furthermore, when the sulfonated phenolic resin used for synergistic enhancement was omitted from the formulation, the peel strength also showed a significant decline. This indicates that the polar additive plays an important role in interfacial wetting and polar coordination in the pressure-sensitive adhesive network, effectively synergizing the interaction between the polyether segments and the silicone-based surface, thereby increasing the actual effective bonding area of ​​the system. This intermolecular polar matching mechanism further amplifies the advantages of the grafted structure, forming a synergistically stable structure.

[0072] The test results above confirm that the technical advantages of this system stem not only from the flexibility and flowability control of the adhesive layer itself, but also from the functional synergy between the active grafting interface and the adhesive layer. The grafting layer is covalently fixed to the substrate through a photoinduced reaction, while the adhesive layer achieves a dynamic balance between structural stability and adhesive elasticity through multiphase components, thereby jointly constructing a high-adhesion, high-durability adhesive system.

[0073] Test Example 2: This experiment was used to test the initial adhesion properties of the samples prepared in Example 1 and Comparative Examples 2, 3 and 6. The steel ball rolling method was used for evaluation to simulate the adhesion effect at the moment of application in actual use.

[0074] The experimental steps are as follows: 1. Sample preparation: Cut all samples into strips 25 mm wide and 100 mm long, remove the release film to expose the adhesive surface. Use a flat, clean glass plate as the test substrate.

[0075] 2. Attachment settings: Place the sample with the adhesive side facing up on the glass plate, fix one end, and maintain moderate tension on the adhesive surface to avoid wrinkles or loosening.

[0076] 3. Test Operation: A standard rolling ball (made of stainless steel, 11 mm in diameter) was used to roll freely from a 30° inclined groove. The starting height of the ball was fixed, and the distance the ball rolled on the sample surface was measured (in cm).

[0077] Each sample was tested three times, and the effective distance the ball rolled before coming to a stop was recorded. The average value was taken as the initial tack performance index. The shorter the rolling distance, the stronger the initial tack.

[0078] 4. Control of experimental conditions: The ambient temperature was 23±1℃ and the relative humidity was 50±5%. The test was conducted on the sample after it had been standing for 30 minutes to ensure that the system was fully stable.

[0079] The experimental results are shown in Table 2: Table 2. Initial tack test results of silicone tape samples with different formulations (rolling ball method) Note: A shorter rolling distance indicates higher initial tack. This experiment demonstrates that the properly configured liquid elastomer in the examples plays a crucial role in the adhesive layer. Liquid SEBS, through its viscoelastic properties, achieves rapid "engagement" with the micro-surface of the steel ball upon contact, forming a sufficient interfacial adhesion contact area and effectively hindering rolling. In the comparative example, when the elastomer content is insufficient, the system cannot provide the required rapid deformation and recovery response, resulting in a significant decrease in initial tack and an increase in sliding distance.

[0080] In samples without crosslinking agents, the adhesive layer structure is loose and lacks sufficient support, leading to localized flow or delayed deformation. This results in an inability to respond promptly to external forces and the failure to quickly form a stable adhesion interface. Crosslinking not only helps form a certain three-dimensional network framework but also enhances the initial interlocking force by restricting the microscopic flowability of the system, thus allowing for a faster strain response.

[0081] Furthermore, in the absence of synergistic tackifiers, polymer molecular chains struggle to fully spread and extend at the adhesion interface, resulting in decreased polar adsorption capacity and weakened instantaneous adsorption force, manifested as increased rolling distance. This indicates that polar matching components in the adhesive system can promote interfacial wetting and initial contact interactions, enhancing overall initial tack behavior, and are closely related to the structural synergy of the entire molecular system.

[0082] The overall results indicate that excellent initial adhesion depends not only on the presence of the flexible component but also on the combined participation of the elastic network structure and the polar synergistic system. Only through comprehensive optimization in structural design and molecular mechanisms can rapid, stable, and reliable instantaneous adhesion performance be achieved.

[0083] Test Example 3: This experiment was used to evaluate the adhesion retention ability of the samples prepared in Example 1 and Comparative Examples 3, 5 and 6 under continuous external force, reflecting the structural stability and anti-flow performance of the adhesive layer.

[0084] The experimental steps are as follows: 1. Sample preparation: Cut all silicone tape samples to 25mm×70mm, remove the release film, and adhere them to a clean glass plate, ensuring that the 25mm×25mm area is in contact with the glass, with the rest hanging down.

[0085] 2. Adhesion process: Use a 2kg standard roller to press the bonding area back and forth twice to ensure a tight contact. After bonding, let it stand at room temperature for 30 minutes to stabilize the system.

[0086] 3. Loading test: Hang a 1kg weight vertically at the free end of the test strip and record the time (in minutes) required from the start of loading until the sample peels off or slips. If no displacement occurs within 180 minutes, record it as 180+.

[0087] 4. Repeated trials: Each sample was tested in triplicate, and the average value was taken as the tackiness result for that sample. The ambient temperature was maintained at 23±1℃ and the relative humidity at 50±5%.

[0088] The experimental results are shown in Table 3: Table 3. Adhesion test results of silicone tape samples with different formulations (vertical load method) Sample number Holding time (min) Test 1 Test 2 Test 3 Example 1 180+ 180+ 180+ 180+ Comparative Example 3 24 22 25 25 Comparative Example 5 51 48 53 52 Comparative Example 6 67 64 70 68 Note: 180+ indicates that no slippage or peeling occurred at the end of the test; The test results show that in systems without a cross-linked structure, the adhesive layer exhibits significant structural relaxation and flow tendency due to the lack of effective network constraints between molecular chains, leading to rapid shear slip under gravity loads. The lack of a three-dimensional support framework directly affects the shear modulus and stable adhesion time of the adhesive layer.

[0089] When certain components are mixed in excess of their limits, although the initial tack is acceptable, the imbalance in the proportion of the main polymer leads to heterogeneity of the internal structure, increased flowability, or phase instability, ultimately reducing shear retention force. This indicates that the structural balance of the system has a direct impact on tack performance; simply adding viscous substances cannot improve the overall retention force and may instead weaken the durability of the network structure.

[0090] Furthermore, in the comparative examples lacking the synergistic adhesive component, although the adhesion holding time was shorter than that of the complete structure system, it was still significantly better than that of the control without cross-linking. This indicates that the polar component not only enhances the initial contact ability of adhesion in the structure, but also provides additional interfacial traction through intermolecular interactions, slowing down the overall shear failure rate. This synergistic effect is clearly crucial for improving adhesion stability.

[0091] In summary, the essence of adhesive retention depends not only on the flow characteristics of the adhesive layer molecules, but also on the rigid support of the cross-linked network and the structural coupling of the polar system. By rationally introducing multiphase structures and forming a mutually complementary elastic-polar-anchoring ternary system, the stability of the adhesive layer under long-term stress can be significantly improved, ensuring its reliable and durable performance in practical applications.

[0092] Test Example 4: This experiment was used to test the retention of adhesive properties of the samples prepared in Example 1 and Comparative Examples 2, 4 and 5 under continuous high temperature conditions, simulating the adhesive stability of the products under thermal aging conditions.

[0093] The experimental steps are as follows: 1. Sample preparation: Cut the sample to a standard size of 25mm×100mm, remove the release film, and attach the adhesive surface to a clean glass plate with an adhesion area of ​​25mm×25mm.

[0094] 2. Adhesion process: Use a standard pressure roller (2kg) to roll back and forth twice over the bonding area to ensure full contact between the adhesive layer and the glass surface. After bonding, let it stand at room temperature for 1 hour to allow the adhesive structure to fully stabilize.

[0095] 3. Heat aging treatment: The bonded sample, along with the glass substrate, was placed in a constant-temperature forced-air drying oven and aged at 70°C for 72 hours. No external force was applied during the process.

[0096] 4. Post-aging assessment: Remove the sample from the oven and allow it to cool naturally to room temperature. Immediately afterward, perform a 180° peel strength test (using the same method as Experiment 1) and observe whether there is any delamination, glue overflow, or structural damage at the adhesive interface.

[0097] 5. Data Recording: Record the peel strength after aging and conduct three parallel tests. Take the average value as the performance index of heat aging retention.

[0098] The experimental results are shown in Table 4: Table 4. Peel strength of silicone tape samples with different formulations after heat aging (70℃×72h) Sample number Peel strength after aging (N / 25mm) Test 1 Test 2 Test 3 Example 1 5.21 5.24 5.19 5.2 Comparative Example 2 1.68 1.73 1.61 1.71 Comparative Example 4 2.07 1.98 2.14 2.09 Comparative Example 5 3.12 3.06 3.14 3.17 Experimental data show that the sample with the optimized structure maintains high peel strength even after high-temperature aging, indicating that its adhesive structure possesses good thermal stability and adhesion durability. This performance stems from the chemical anchoring structure between the adhesive layer and the substrate, namely the covalent bond interface formed under UV grafting, which effectively suppresses interface damage caused by thermal stress and maintains adhesion strength.

[0099] In contrast, samples without cross-linking or anchoring interfaces undergo molecular chain migration and rearrangement during aging, leading to the peeling of the adhesive layer from the interface and a significant decrease in adhesion performance. In particular, structures in the main adhesive system that rely solely on physical adsorption for bonding are prone to flow, debonding, or softening of the adhesive layer during thermal aging, demonstrating that structures relying on a single molecular chain are insufficient to support stability under prolonged thermal aging.

[0100] Furthermore, samples without polar synergistic components in their formulations exhibited further weakened interfacial wettability and insufficient polar forces during high-temperature aging, making it difficult to maintain good interfacial contact and leading to a rapid decline in adhesion performance. This demonstrates that the heat resistance of an adhesive system depends not only on the thermal stability of the base adhesive material but also, and perhaps more importantly, on the integrity of the interfacial structure and the synergistic stabilizing ability of its multiple components.

[0101] In summary, the adhesive structure of this invention maintains high adhesion even after exposure to high temperatures, thanks to the construction of the cross-linked network, the introduction of the interfacial grafting anchoring mechanism, and the multi-dimensional synergy of the polar compatibility system. These three factors work together to significantly improve the structural stability and adhesion durability of the system under thermal aging conditions, representing a key pathway to achieving high-temperature resistant adhesive performance.

[0102] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A silicone tape with good adhesion, characterized in that, It includes, from bottom to top, a backing layer, an interface grafting activation layer, a main pressure-sensitive adhesive layer, and a release film; The grafted activation layer comprises the following components by weight: Acryloyloxypropyltriethoxysilane 3-8 parts; 5-10 parts of isocyanate-terminated polyester block polymer; 30-60 parts of ethyl acetate; Cyclohexanone 10-25 parts; Photoinitiator 0.5–2 parts; The main pressure-sensitive adhesive layer comprises the following components by weight: 40-60 parts of acrylic acid-polyether block copolymer; 20-30 parts of aminosilane-modified polyurethane prepolymer; 5-15 parts of liquid SEBS elastomer; 3-5 parts of sulfonated phenolic resin; 0.5–1.5 parts of HDI-type isocyanate crosslinking agent; 10-20 parts of methyl ethyl ketone (MEK).

2. The silicone tape with good adhesion according to claim 1, characterized in that, The silicone substrate layer is made of silicone elastomer with a Shore A hardness of 25-40 and a thickness of 0.1-0.5 mm.

3. The silicone tape with good adhesion according to claim 1, characterized in that, The isocyanate-terminated polyester block polymer has an average molecular weight of 2000–5000 g / mol, and the terminating groups are isocyanate functional groups.

4. The silicone tape with good adhesion according to claim 1, characterized in that, The coating amount of the interface grafting activation layer is 5–20 g / m². 2 Furthermore, after being irradiated with ultraviolet light at a wavelength of 365 nm for 20–60 seconds, a grafted structure is formed.

5. The silicone tape with good adhesion according to claim 1, characterized in that, The acrylic-polyether block copolymer has a hydrophilic polyether segment content of 20-35 wt% and a number average molecular weight of 5000-10000 g / mol.

6. The silicone tape with good adhesion according to claim 1, characterized in that, The liquid SEBS elastomer is a styrene-ethylene / butene-styrene block copolymer with a styrene content of 20-30 wt%.

7. The silicone tape with good adhesion according to claim 1, characterized in that, The dry film thickness of the main pressure-sensitive adhesive layer is 30–80 μm.

8. A method for preparing a silicone tape with good adhesion as described in any one of claims 1-7, characterized in that, Includes the following steps: 1) Prepare a backing silicone sheet, wherein the organosilicon elastomer is compounded, calendered, and hot-cured to form a silicone sheet with a thickness of 0.1 to 0.5 mm; 2) The interface grafting activation solution is uniformly coated on one side of the silica sheet, dried, and then irradiated under ultraviolet light with a wavelength of 365 nm to form a grafted layer. 3) After the main pressure-sensitive adhesive layer material is mixed evenly, it is coated on the surface of the grafted layer. After curing, the release film is laminated to obtain the finished product.

9. The preparation method according to claim 8, characterized in that, The ultraviolet irradiation step uses an energy density of 0.5–2.0 mW / cm². 2 .

10. The preparation method according to claim 8, characterized in that, The curing step of the main pressure-sensitive adhesive layer is carried out at 80-90°C for 10-20 minutes.

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