Continuous dissipation type branched polymer pressure-sensitive adhesive as well as preparation method and application thereof

Abstract

The invention provides a continuous dissipation type branched polymer pressure-sensitive adhesive as well as a preparation method and application thereof, and relates to the field of high polymer materials. The continuous dissipative branched polymer pressure-sensitive adhesive is prepared from reaction raw materials including a monomer, an initiator and a polyfunctionality chain transfer agent through free radical polymerization reaction, the polyfunctionality chain transfer agent is a compound comprising at least one chain transfer active group and at least one radically polymerizable ethylenically unsaturated group. According to the invention, a branched polymer network is constructed by using a special multifunctional chain transfer agent, and the interface toughness and the adhesion strength of the material are remarkably improved through a continuous energy dissipation mechanism of a branched chain. Meanwhile, the structure keeps good flexibility and wetting capacity, the contradiction of poor wettability caused by high adhesion is effectively solved, and the excellent performance of strong adhesion and rapid adhesion is achieved.

Description

Technical Field

[0001] This invention relates to the field of polymer materials, and more specifically, to a continuously dissipating branched polymer pressure-sensitive adhesive, its preparation method, and its uses. Background Technology

[0002] Pressure-sensitive adhesives are a type of adhesive that can quickly adhere to various material surfaces at room temperature with the application of only light pressure. Their significant advantage lies in achieving effective adhesion without the need for solvents, heating, chemical activation, or pretreatment of the substrate, thus leading to their widespread application in industrial production and daily life.

[0003] To meet higher application demands, existing technologies typically focus on improving the adhesion energy of pressure-sensitive adhesives (PSAs), which is the work required per unit area to separate the PSA from the adherend. A common improvement method is to introduce a large number of high-energy non-covalent bonds, such as hydrogen bonds, into the polymer network. When the PSA undergoes bulk deformation during use, the breaking of these bonds dissipates energy, thereby improving the material's adhesion performance to some extent.

[0004] However, this method of enhancing adhesion energy by introducing high-energy bond interactions has significant drawbacks. The introduction of high-energy chemical bonds leads to regional hardening of molecular chain segments, resulting in an increase in material modulus. In engineering applications, this directly manifests as poorer wettability of the material on the substrate surface. This means that such high-adhesion-energy adhesives often require longer contact times and larger preloads to achieve effective bonding, which fundamentally contradicts the design intent of pressure-sensitive adhesives to provide "fast, light-pressure bonding."

[0005] Furthermore, in existing technologies, the interfacial wetting ability and bulk energy dissipation ability of materials are often mutually restrictive: increasing rigidity to achieve high dissipation sacrifices wetting ability, while reducing rigidity to maintain wetting leads to insufficient dissipation ability. This makes it difficult to overcome the adhesion energy bottleneck of pressure-sensitive adhesives. Therefore, how to significantly improve energy dissipation ability without sacrificing wetting ability, and achieve both strong and rapid adhesion, is a pressing technical challenge in this field.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a continuously dissipating branched polymer pressure-sensitive adhesive, its preparation method, and its applications. The continuously dissipating branched polymer pressure-sensitive adhesive, by constructing a continuously dissipating branched structure, significantly improves the interfacial toughness and adhesion strength of the pressure-sensitive adhesive while maintaining excellent wettability and achieving rapid adhesion.

[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: In a first aspect, the present invention provides a continuously dissipating branched polymer pressure-sensitive adhesive, wherein the continuously dissipating branched polymer pressure-sensitive adhesive is prepared by a free radical polymerization reaction of reactive raw materials including monomers, initiators and multifunctional chain transfer agents; The multifunctional chain transfer agent is a compound containing at least one chain transfer active group and at least one free radical polymerizable olefinic unsaturated group.

[0009] In an optional embodiment, the chain transfer active group includes at least one selected from dithioester, trithiocarbonate, dithiocarbamate, xanthate, organosulfone, and organoselenoyl groups; and / or, The multifunctional chain transfer agent comprises at least one selected from 2-(methacryloyloxy)ethyl-4-cyano-4-(dodecylthiocarbonyl)thioalkylpentanoate, 2-(dodecyltrithiocarbonate)ethyl methacrylate, S-allyl-S′-(α,α′-dimethyl-α′′-acetic acid)trithiocarbonate, 2-(N,N-diethyldithiocarbamoyl)ethyl methacrylate, 4-cyano-4-(thiobenzoylthio)pentanoic acid vinyl ester, 2-(isopropylxanthyl)ethylacrylamide, and benzyl-3-(methacryloyloxy)propyl dithiobenzoate; and / or The initiator comprises at least one selected from azobisisobutyronitrile, azobisisovalerate, azobisisoheptanenitrile, dimethyl azobisisobutyrate, 1-(cyano-1-methylethylazo)formamide, 1,1"-azo(cyanocyclohexane), benzoyl peroxide, dicumyl peroxide, methyl ethyl ketone peroxide, di-tert-butyl peroxide, potassium persulfate, and ammonium persulfate; and / or, The monomer comprises at least one of acrylate monomers, acrylic monomers, acrylamide monomers, and vinyl monomers; or, the monomer comprises at least one of butyl methacrylate, hexafluorobutyl methacrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, phenyl methacrylate, benzyl methacrylate, isobornyl methacrylate, glycidyl methacrylate, methyl acrylate, cyclohexyl acrylate, benzyl acrylate, hydroxyethyl methacrylate, hydroxyethyl methacrylate, diethylaminoethyl methacrylate, acrylic acid, methacrylic acid, acrylamide, isoacrylate acrylamide, dimethylacrylamide, diethylacrylamide, hydroxyethylacrylamide, sodium vinyl sulfonate, vinyl glycol monoether, and styrene.

[0010] In an optional embodiment, the molar ratio of the multifunctional chain transfer agent to the monomer is 1:(100-10000); and / or, The molar ratio of the initiator to the multifunctional chain transfer agent is 1:(0.5-20).

[0011] In an optional embodiment, the reaction raw materials further include an organic solvent; Preferably, the boiling point of the organic solvent is higher than the initiation temperature of the initiator; Preferably, the volume ratio of the organic solvent to the reactants (excluding the organic solvent) in the reaction raw materials is 1:(0.1-10); Preferably, the organic solvent includes at least one selected from dioxane, toluene, xylene, ethyl acetate, butyl acetate, butanone, methyl isobutyl ketone, cyclohexanone, N,N-dimethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0012] In a second aspect, the present invention provides a method for preparing a continuously dissipating branched polymer pressure-sensitive adhesive as described in any of the foregoing embodiments, comprising: The reaction raw materials containing the monomer, the initiator and the multifunctional chain transfer agent are dissolved in an organic solvent to form a precursor liquid; The precursor fluid is subjected to deoxygenation treatment; The deoxygenated precursor liquid is heated to carry out a free radical polymerization reaction; After the reaction is complete, the organic solvent and residual monomers are removed to obtain the continuously dissipating branched polymer pressure-sensitive adhesive.

[0013] In an optional embodiment, the deoxygenation treatment time is 1 min to 3 h; and / or, The deoxygenation treatment is performed by introducing nitrogen gas; and / or, The free radical polymerization reaction is carried out at a temperature of 40℃ to 110℃; and / or, The reaction time for the free radical polymerization reaction is 1 h to 72 h; and / or, The step of removing the organic solvent and residual monomer includes drying for 3 to 24 hours under a vacuum of 0.1 Pa to 1000 Pa and a temperature of 20°C to 150°C.

[0014] Thirdly, the present invention provides a pressure-sensitive adhesive product, comprising a substrate and a pressure-sensitive adhesive layer disposed on at least one surface of the substrate; The pressure-sensitive adhesive layer comprises a continuously dissipative branched polymer pressure-sensitive adhesive as described in any of the foregoing embodiments.

[0015] Fourthly, the present invention provides the use of a multifunctional chain transfer agent in the preparation of a continuously dissipating branched polymer pressure-sensitive adhesive as described in any of the foregoing embodiments, wherein the multifunctional chain transfer agent is a compound comprising at least one chain transfer active group and at least one free radical polymerizable olefinic unsaturated group.

[0016] Fifthly, the present invention provides the use of a continuously dissipating branched polymer pressure-sensitive adhesive as described in any of the foregoing embodiments in the preparation of pressure-sensitive tapes, pressure-sensitive sheets or protective films.

[0017] In a sixth aspect, the present invention provides the use of a continuously dissipating branched polymer pressure-sensitive adhesive as described in any of the foregoing embodiments in bonding glass, plastic or metal substrates.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: The continuously dissipating branched polymer pressure-sensitive adhesive of this invention utilizes a multifunctional chain transfer agent with both chain transfer active groups and free radical polymerizable olefinic unsaturated groups to construct a unique branched polymer topology through free radical polymerization. This special chemical structure allows the branched chains to slowly and continuously store and release energy when the polymer chains are deformed by external forces, thus forming a long stress plateau during peeling and achieving continuous energy dissipation, significantly improving the interfacial toughness and adhesion energy of the material. Simultaneously, unlike traditional high-bond-energy hardening networks, this branched structure maintains good flexibility, preventing a significant increase in the overall glass transition temperature of the material. This allows the pressure-sensitive adhesive to retain excellent interfacial wetting ability while possessing extremely high adhesion strength, solving the technical problem of the trade-off between high adhesion energy and rapid wetting ability in existing technologies. Furthermore, the free radical polymerization reaction involving a multifunctional chain transfer agent enables the efficient one-step construction of the desired branched structure, with a simple preparation process and no need for complex post-processing. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a peel force-displacement curve obtained in the 90-degree peel test for Comparative Example 1. Figure 2 This is a peel force-displacement curve obtained in the 90-degree peel test for Comparative Example 2. Figure 3 This is a peel force-displacement curve obtained in the 90-degree peel test of Example 1; Figure 4 This is a peel force-displacement curve obtained in the 90-degree peel test of Example 2; Figure 5This is a peel force-displacement curve obtained in the 90-degree peel test of Example 3; Figure 6 This is a peel force-displacement curve obtained in the 90-degree peel test of Example 4; Figure 7 This is a peel force-displacement curve obtained in the 90-degree peel test of Example 5; Figure 8 This is a peel force-displacement curve obtained in the 90-degree peel test for Comparative Example 3; Figure 9 This is a peel force-displacement curve obtained in the 90-degree peel test for Comparative Example 4. Figure 10 This is a peel force-displacement curve obtained in the 90-degree peel test for Comparative Example 5. Figure 11 This is a peel force-displacement curve obtained in the 90-degree peel test for Comparative Example 6; Figure 12 This is a comparison diagram of the interfacial toughness of samples with different number-average molecular weights in the embodiments and comparative examples of the present invention; Figure 13 This is a comparison chart of the actual stress-strain curves of Example 4 and Comparative Example 6; Figure 14 This is a graph showing the probe viscosity test results of Example 4; Figure 15 This is a comparison diagram of the initial tack and interfacial toughness properties between the embodiments of the present invention and the prior art (references); Figure 16 A comparison diagram of the interfacial toughness of Example 4 and Examples 6-8 using different multifunctional chain transfer agents; Figure 17 This is the frequency scan rheological master curve for Example 4 (branched); Figure 18 The frequency scan rheological master curve is shown in Comparative Example 6 (linear). Detailed Implementation

[0021] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0022] This application provides a continuously dissipating branched polymer pressure-sensitive adhesive, which is prepared by free radical polymerization of reactive raw materials including monomers, initiators and multifunctional chain transfer agents; wherein, the multifunctional chain transfer agent is a compound containing at least one chain transfer active group and at least one free radical polymerizable olefinic unsaturated group.

[0023] The aforementioned pressure-sensitive adhesive is prepared by free radical polymerization of reactants comprising monomers, initiators, and multifunctional chain transfer agents. The monomers refer to the basic units capable of undergoing free radical polymerization to form the polymer backbone. In this embodiment, the polymer segments formed after monomer polymerization constitute the matrix (body) of the pressure-sensitive adhesive material. The choice of monomers determines the basic physicochemical properties of the polymer, such as glass transition temperature (Tg), polarity, and basic flexibility.

[0024] The aforementioned initiator refers to a substance that, under reaction conditions, can generate free radicals, thereby initiating a polymerization reaction between monomers and multifunctional chain transfer agents. Its function is to initiate the chain growth process.

[0025] The aforementioned multifunctional chain transfer agent is the core component of this embodiment and a key feature distinguishing it from traditional technologies. It can refer to a special class of compounds whose molecular structure simultaneously possesses two different reactive functional groups: (1) Chain transfer active group, which can participate in reversible addition-fragmentation chain transfer (RAFT) or other living radical polymerization processes. Its functions may include: controlling the growth of polymer chains, adjusting molecular weight, and retaining activity at the ends of polymer chains in order to initiate the growth of new branched chains.

[0026] (2) Free radical polymerizable olefinic unsaturated groups (usually containing carbon-carbon double bonds) endow chain transfer agents with properties similar to "monomers", enabling them to be incorporated into the polymer backbone through copolymerization.

[0027] In this embodiment, a unique "continuously dissipative branched polymer" structure was constructed through one-step free radical polymerization of the above raw material system. The formation principle is as follows: Firstly, regarding the construction of branched structures (topology control), during polymerization, multifunctional chain transfer agents copolymerize into the polymer backbone through their "olefinic unsaturated groups," thereby introducing potential growth sites (i.e., chain transfer active groups) on the backbone. Subsequently, initiators or active free radicals attack these "chain transfer active groups" located on the backbone, initiating the growth of new polymer chains (side chains / branched chains). This unique "monomer + polymerizable chain transfer agent" reaction mode results in a final product forming a polymer with a highly controllable hyperbranched or multibranched topology, rather than a traditional linear polymer or random crosslinked network.

[0028] Secondly, based on the continuous energy dissipation mechanism (performance principle), "continuous dissipation" means that the material can continuously consume energy for a long time when it is deformed under external force (such as peeling force).

[0029] In addition, regarding linear polymers, it should be noted that after yielding, the stress of ordinary linear polymers usually decays rapidly and cannot continue to resist external forces, resulting in low interfacial toughness.

[0030] In the branched polymer constructed in the embodiments of this application, numerous long side branches (branched chains) play a crucial role in the material deformation process. When the pressure-sensitive adhesive layer is stretched, these branched chains can slowly and continuously provide energy storage and release through the untangling, orientation, and slippage of molecular chains. This microscopic movement manifests as a relatively long "stress plateau" on the macroscopic mechanical curve, forming a large energy dissipation region at the peeling tip, thereby significantly increasing the work (adhesion energy) required to separate the adhesive layer from the substrate.

[0031] Based on the aforementioned basic components and mechanisms of action, this pressure-sensitive adhesive exhibits the following significant advantages: First, it achieves strong adhesion (high interfacial toughness). Due to the continuous energy dissipation capability brought about by the branched structure, the adhesion energy (or interfacial toughness) of this pressure-sensitive adhesive is significantly improved, breaking through the performance bottleneck of traditional linear polymers. Second, it possesses fast adhesion (excellent wettability). Unlike conventional techniques that enhance adhesion energy by introducing strong hydrogen bonds (leading to material hardening), the branched chains in this embodiment maintain the flexibility of the polymer chains themselves, without significantly increasing the glass transition temperature (Tg) or modulus of the material. Therefore, this pressure-sensitive adhesive maintains good softness and fluidity at room temperature, enabling rapid wetting of the adhered surface and establishing effective adhesion without prolonged pressure. Furthermore, in terms of the preparation process, free radical polymerization (especially the thermally initiated one-pot method) is employed, resulting in a simple and controllable reaction process. No complex subsequent chemical modification or physical crosslinking steps are required. The degree of branching and performance of the polymer can be precisely controlled by adjusting the type and amount of multifunctional chain transfer agents.

[0032] Furthermore, it should be noted that any compound that simultaneously satisfies the two structural characteristics of "having chain transfer activity" and "having polymerizable double bonds" is within the scope of protection claimed in this embodiment and can achieve the construction of the above-mentioned branched structure.

[0033] Furthermore, in practical applications, the monomers mentioned above can be flexibly selected within the technically acceptable range and the method and process acceptable range of the product provided in this embodiment. For example, a combination of soft monomers (providing initial tack) and hard monomers (providing cohesion) can be selected.

[0034] In summary, in this embodiment, a branched polymer structure with continuous energy dissipation capability was constructed by using a multifunctional chain transfer agent with both chain transfer activity and polymerizable double bonds for free radical polymerization. This structure utilizes the continuous energy storage and release mechanism of the branched chains during deformation to significantly extend the stress plateau and greatly improve interfacial toughness and adhesion strength. Simultaneously, this branched system maintains the flexibility of the molecular chains and a low glass transition temperature, ensuring excellent wettability of the material to the substrate. This effectively overcomes the problem of poor wettability caused by high adhesion energy in traditional pressure-sensitive adhesives, achieving a synergistic unity of strong and fast adhesion, and the preparation process is simple and efficient.

[0035] For example, in a preferred embodiment, the interfacial toughness of the pressure-sensitive adhesive prepared in the embodiments of this application on a glass substrate can reach up to 6000 J / m. 2 Furthermore, the adhesion can reach equilibrium within 30 seconds, breaking through the bottleneck of existing technologies where high adhesion energy and rapid wetting are difficult to achieve simultaneously.

[0036] In some embodiments, the chain transfer active group includes at least one selected from dithioester, trithiocarbonate, dithiocarbamate, xanthate, organosulfonate, and organoselenoside groups.

[0037] These groups are the core functional units of living radical polymerization (especially reversible addition-fragmentation chain transfer polymerization, RAFT). During radical polymerization, these groups can undergo reversible addition-fragmentation reactions with growing free radicals. This allows the polymer chain to remain "active" during growth, meaning the chain ends do not permanently lose their reactivity due to bimolecular termination, but can continue to initiate monomer polymerization under the action of initiators or heat.

[0038] It should be noted that in the system provided in this embodiment, since the multifunctional chain transfer agent copolymerizes onto the main chain through the double bond at the other end, these "chain transfer active groups" become "growth points" on the main chain. New polymer chains (branched chains) will grow from these groups, thereby forming a defined branched topology rather than random crosslinking.

[0039] The above limitation covers all the mainstream active group types in the current RAFT polymerization field, ensuring the universality of the technical solution. Different groups (such as trithiocarbonate and dithioester) have different chain transfer constants, which can be matched and adjusted according to the activity of the selected monomer.

[0040] It should be noted that although the embodiments of this application mainly demonstrate the effects of sulfur-containing active groups (such as dithioesters and trithiocarbonates), those skilled in the art, based on the general mechanism of living radical polymerization (especially RAFT / MADIX polymerization), know that organosen groups (such as diselenates) and organosenone groups also possess the ability to undergo reversible addition-fracture reactions with free radicals. In terms of polymerization kinetics, they are highly similar to and substitutable with sulfur-containing groups, and can all introduce active sites on the polymer backbone and initiate branched chain growth through the same mechanism. Therefore, these groups are equivalent in the technical solution of this invention and can all achieve the technical objective of constructing a continuously dissipative branched structure.

[0041] In some embodiments, the multifunctional chain transfer agent comprises at least one selected from 2-(methacryloyloxy)ethyl-4-cyano-4-(dodecylthiocarbonyl)thioalkylpentanoate, 2-(dodecyltrithiocarbonate)ethyl methacrylate, S-allyl-S′-(α,α′-dimethyl-α′′-acetic acid)trithiocarbonate, 2-(N,N-diethyldithiocarbamoyl)ethyl methacrylate, 4-cyano-4-(thiobenzoylthio)pentanoate vinyl ester, 2-(isopropylxanthyl)ethylacrylamide, and benzyl-3-(methacryloyloxy)propyl dithiobenzoate.

[0042] All of the above compounds possess two parts in their molecular structure: (1) The polymerizable end (such as methacryloyloxy, vinyl, allyl) corresponds to the "olefinic unsaturated group" in the aforementioned embodiments and is responsible for participating in copolymerization and entering the polymer backbone.

[0043] (2) The chain transfer end (such as dodecyl thiocarbonyl, trithiocarbonate, etc.) corresponds to the "chain transfer active group" in the aforementioned embodiments and is responsible for initiating the growth of branched chains.

[0044] These specific compounds are key substances for achieving the "continuous dissipation" mechanism in this embodiment. By selecting these specific molecules, branching points can be precisely introduced during the polymerization process. Compared to ordinary crosslinking agents (which only link without controlling molecular weight) or ordinary chain transfer agents (which only control molecular weight without forming branching), these compounds achieve a synergy between "structure building" and "molecular weight control".

[0045] The use of these specific structures enables the branched chains in the final pressure-sensitive adhesive to effectively untangle and continuously dissipate energy during stretching, resulting in high interfacial toughness. At the same time, the presence of the branched structure does not excessively restrict chain segment movement, maintaining the material's low Tg and rapid wetting ability.

[0046] In some embodiments, the initiator includes at least one selected from azobisisobutyronitrile, azobisisovalerate, azobisisoheptanenitrile, dimethyl azobisisobutyrate, 1-(cyano-1-methylethylazo)formamide, 1,1"-azo(cyanocyclohexane), benzoyl peroxide, dicumyl peroxide, methyl ethyl ketone peroxide, di-tert-butyl peroxide, potassium persulfate, and ammonium persulfate.

[0047] It should be noted that all of the above initiators can be thermal initiators. Under heating conditions (e.g., 40–110 °C), these compounds undergo bond breaking and decomposition to generate primary free radicals. The above initiators can achieve their effect in two stages: first, the reaction initiation stage, where the generated free radicals attack the double bonds of the monomers, initiating polymerization chain growth; second, the CTA activation stage, where the generated free radicals attack the active groups of the chain transfer agent, initiating the branching reaction.

[0048] These initiators have moderate half-lives, making them suitable for solution polymerization processes. They ensure stable reaction and are inexpensive, making them easy to industrialize.

[0049] In some embodiments, the monomer includes at least one of acrylate monomers, acrylic monomers, acrylamide monomers, and vinyl monomers.

[0050] In some other preferred embodiments, the monomer includes at least one of butyl methacrylate, hexafluorobutyl methacrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, phenyl methacrylate, benzyl methacrylate, isobornyl methacrylate, glycidyl methacrylate, methyl acrylate, cyclohexyl acrylate, benzyl acrylate, hydroxyethyl methacrylate, hydroxyethyl methacrylate, diethylaminoethyl methacrylate, acrylic acid, methacrylic acid, acrylamide, isoacrylic acid acrylamide, dimethacrylamide, diethylacrylamide, hydroxyethylacrylamide, sodium vinyl sulfonate, vinyl glycol monoether, and styrene.

[0051] In terms of monomers, they can include soft monomers (such as butyl acrylate, isooctyl acrylate, etc.), which can have a lower homopolymer glass transition temperature (Tg), mainly providing the necessary flexibility, initial tack, and wetting properties (fast tack) for pressure-sensitive adhesives; and hard monomers / functional monomers (such as acrylic acid, acrylamide, methyl methacrylate, etc.), which can have a higher Tg or polar groups. These mainly provide the cohesive strength (preventing residue), heat resistance, and specific adhesion to the substrate (such as hydrogen bonding) of the pressure-sensitive adhesive.

[0052] In this embodiment, the polymer's "core" is constructed through the combination (copolymerization) of the aforementioned monomers. The "branched backbone" constructed by the multifunctional chain transfer agent can only function based on the chain segments formed by these monomers.

[0053] Furthermore, the specific monomer selection allows for the adjustment of the pressure-sensitive adhesive's basic properties (such as modulus and Tg). Combined with the branching technology of this application, even when using a large number of soft monomers to ensure wettability, extremely high adhesion strength can be obtained through the energy dissipation mechanism of the branched structure, thus resolving the contradiction between "softness" and "strength".

[0054] In some embodiments, the molar ratio of the multifunctional chain transfer agent to the monomer is 1:(100 to 10000). For example, this molar ratio can be: 1:100, 1:500, 1:1000, 1:2000, 1:3000, 1:4500, 1:6000, 1:7500, 1:9000, 1:10000, etc.

[0055] It should be noted that the above ratio determines the relative amounts of "growth points" (chain transfer agents) and "growth raw materials" (monomers) in the polymerization reaction system. In terms of polymerization mechanism, this parameter directly regulates the branching density (topology) and average molecular weight (chain length) of the final branched polymer.

[0056] This molar ratio means that for every 1 mole of a multifunctional chain transfer agent, there are 100 to 10,000 moles of monomer.

[0057] The multifunctional chain transfer agent, acting as a branching center, results in a higher content (i.e., a ratio closer to 1:100) leading to a denser network of branching points in the polymer, resulting in a relatively smaller molecular weight and a more compact structure. Conversely, a lower content (i.e., a ratio closer to 1:10000) results in sparser branching points, longer branched chains, and polymer properties that are closer to those of a linear polymer. The core of this embodiment lies in "continuous energy dissipation." This dissipation capability relies on the untangling motion of appropriately long branched chains during deformation.

[0058] In this embodiment, by limiting the branching length to a range of 1:(100~10000), it is ensured that the formed polymer is neither too dense, resulting in an excessively low molecular weight (insufficient cohesion and inability to hold), nor too sparse, degenerating into a typical linear polymer (lacking dissipation mechanisms and exhibiting low interfacial toughness). Within this range, the branched chains provide optimal energy storage and release efficiency, exhibiting a significantly extended stress plateau in peel tests, thereby achieving high interfacial toughness (strong adhesion). Simultaneously, the appropriate chain length ensures the macroscopic flexibility of the material, maintaining excellent wettability (fast adhesion).

[0059] In this embodiment, the molar ratio range is defined as 1:100 to 1:10000. It is worth noting that while the material exhibits the best balance of mechanical properties within the preferred range (e.g., 1:1000), in lower ratios (e.g., 1:5000 to 1:10000), although the branching density decreases, the extremely long branched segments impart excellent flexibility and extremely low modulus to the material. This makes it uniquely valuable in specific applications where wettability requirements are extremely high but absolute shear strength requirements are relatively low (e.g., ultra-thin protective films, easy-to-peel patches). Therefore, this wide range covers the full range of product needs from 'strong adhesion' to 'fast adhesion / micro adhesion'.

[0060] For example, when the ratio is appropriate, such as 1:1000, the interfacial toughness can reach the corresponding peak value; while when the ratio is too low (such as the ratio of near-linear polymers in the comparative example), the stress plateau disappears and the toughness decreases. This proves that this range is the key window for achieving the purpose of the invention.

[0061] In some embodiments, the molar ratio of the initiator to the multifunctional chain transfer agent is 1:(0.5 to 20). For example, this molar ratio can be: 1:0.5, 1:1, 1:2, 1:4, 1:5, 1:8, 1:10, 1:12, 1:15, 1:20, etc.

[0062] The ratio provided in this embodiment determines the initiation efficiency of the polymerization reaction and the balance between active centers and dormant species. This ratio can represent 0.5 to 20 moles of multifunctional chain transfer agent for every 1 mole of initiator.

[0063] It is important to note that in living radical polymerization (such as RAFT polymerization) or polymerization involving chain transfer mechanisms, the number of free radicals generated by the initiator must be controlled. If there is too little initiator (a ratio far below 1:20), the reaction rate is extremely slow, the conversion rate is low, and it is impossible to effectively activate all the chain transfer agents, resulting in incomplete branching structure construction. If there is too much initiator (a ratio far above 1:0.5), too many primary free radicals will be generated, leading to increased competition for bimolecular termination reactions (dead chain formation), which undermines the characteristics of "living / controllable" polymerization, resulting in uncontrollable product structure and loss of the ideal branched topology.

[0064] By limiting the ratio to 1:(0.5~20), the reaction can be carried out at an appropriate rate, while maximizing the "activity" control function of the multifunctional chain transfer agent, ensuring the synthesis of a structurally regular, molecularly controllable, continuously dissipative branched polymer, thereby guaranteeing the stability of the final pressure-sensitive adhesive product performance.

[0065] In this invention, the molar ratio of initiator to multifunctional chain transfer agent can be adjusted within a wide range from 1:0.5 to 1:20. When the ratio is lower (e.g., 1:20, with less initiator), the polymerization rate is slower, which is more conducive to forming high-molecular-weight and structurally regular branched polymers, suitable for precision applications with extremely high performance requirements. When the ratio is higher (e.g., 1:0.5, with more initiator), the reaction rate is faster, although this may lead to a slight decrease in molecular weight, but it can significantly improve production efficiency, suitable for cost-sensitive industrial production. The preferred ratio shown in the examples (e.g., around 1:2) represents a balance between reaction efficiency and product performance.

[0066] In some embodiments, the reaction raw materials also include an organic solvent.

[0067] In this embodiment, the reaction raw materials include an organic solvent, meaning that solution polymerization is used in this embodiment. The main function of the organic solvent is to act as a reaction medium, dissolving the monomer, initiator, and multifunctional chain transfer agent into a homogeneous "precursor liquid".

[0068] It should be noted that in a homogeneous system, active free radicals, monomers, and chain transfer agents can fully contact and diffuse, which is crucial for the precise molecular structure design (i.e., the construction of branched topologies) relying on "multifunctional chain transfer agents" in this application. Compared to emulsion polymerization or bulk polymerization, solution polymerization makes it easier to control the heat of reaction, preventing burst polymerization or gelation (crosslinking) caused by local overheating, thereby ensuring the formation of soluble, coatable branched polymers rather than insoluble crosslinked networks.

[0069] Furthermore, the boiling point of the organic solvent is higher than the initiation temperature of the initiator.

[0070] In this embodiment, the physical properties (boiling point) of the selected solvent are further limited to be compatible with the chemical properties (thermal decomposition temperature) of the initiator. This embodiment employs thermally initiated free radical polymerization. The initiator (such as AIBN) needs to reach a specific temperature (initiation temperature, for example, 60-80°C) to effectively decompose and generate free radicals. If the solvent's boiling point is below the initiation temperature, the solvent will boil and evaporate before reaching the required reaction temperature, leading to instability in the reaction system, or even preventing the initiation temperature from being reached, thus preventing the reaction from starting or proceeding.

[0071] This example ensures that the polymerization reaction can proceed stably under normal pressure reflux or closed conditions within the optimal activity temperature range of the initiator, guaranteeing the conversion rate and consistency of the product structure.

[0072] Furthermore, the volume ratio of the organic solvent to the reactants (excluding the organic solvent) in the reaction raw materials is 1:(0.1 to 10). For example, this volume ratio can be: 1:0.1, 1:0.5, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:8, 1:10, etc.

[0073] In this embodiment, the volume ratio of solvent to solute (all reaction raw materials other than solvent, including monomers, CTA, and initiators) is provided.

[0074] This ratio essentially regulates the monomer concentration and viscosity of the reaction system. In terms of concentration control (kinetics), the reactant concentration affects the polymerization rate and chain transfer efficiency. A reactant concentration within the range of 1:(0.1–10) is suitable. If there is too much solvent (reactant ratio less than 0.1), the reaction rate is too slow, and the solvent may participate in chain transfer, leading to a lower molecular weight. If there is too little solvent (reactant ratio greater than 10), the system viscosity is too high, making stirring difficult and prone to localized overheating (gel effect), resulting in a wider molecular weight distribution or even uncontrollable crosslinking. In terms of structure control (topology), a suitable dilution helps the multifunctional chain transfer agent to distribute evenly between molecular chains, promoting "branching" rather than "crosslinking," which is a key process window for successfully preparing the branched polymer described in this application.

[0075] Furthermore, the organic solvent includes at least one selected from dioxane, toluene, xylene, ethyl acetate, butyl acetate, butanone, methyl isobutyl ketone, cyclohexanone, N,N-dimethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0076] The aforementioned organic solvents are all good solvents for acrylate monomers and the specific chain transfer agents of this application, and have moderate boiling points (mostly between 70 and 120°C), which not only meet the requirement of "above the initiation temperature", but also facilitate removal by vacuum drying after the reaction (so that the boiling point is too high to be completely removed).

[0077] This application embodiment also provides a method for preparing a continuously dissipating branched polymer pressure-sensitive adhesive as described in any of the foregoing embodiments, comprising: Step S1: Dissolve the reaction raw materials containing the monomer, the initiator and the multifunctional chain transfer agent in an organic solvent to form a precursor liquid.

[0078] This step is the first step in the preparation process, namely, ingredient preparation and mixing. Operationally, all reaction components (monomer, CTA, initiator) are added to the selected organic solvent in proportion, and then physically stirred or shaken to completely dissolve them, forming a homogeneous and transparent mixed solution, also known as the "precursor liquid".

[0079] It is important to note that solution polymerization requires all reactants to be in a homogeneous phase. This ensures that, at the microscale, the free radicals generated by the initiator can contact the monomers and chain transfer agents with equal probability. Only in a homogeneous system can multifunctional chain transfer agents uniformly enter the polymer backbone through copolymerization and subsequently uniformly initiate branched chain growth. Insufficient dissolution (heterogeneous phase) may result in excessively high (forming microgels) or insufficient (forming linear polymers) branching, failing to yield the desired topological structure.

[0080] In this embodiment, a "one-pot" batching method is adopted, which eliminates the need for step-by-step dropwise addition (as is common in seed emulsion polymerization in traditional technologies). This method is simple to operate, greatly reduces process complexity and equipment requirements, and is conducive to large-scale industrial production.

[0081] Step S2: Deoxygenate the precursor liquid.

[0082] In this embodiment, oxygen dissolved in the precursor liquid must be removed before initiating the polymerization reaction. Common methods for achieving this include, but are not limited to, bubbling the solution with an inert gas (such as nitrogen or argon) or using a freeze-thaw cycle.

[0083] It should be noted that oxygen is a potent free radical polymerization inhibitor. Dissolved oxygen rapidly reacts with primary or growing chain radicals generated by the initiator to form stable peroxy radicals, thereby quenching the active center and leading to an indefinite extension of the induction period or even complete cessation of the reaction.

[0084] This embodiment involves living radical polymerization (RAFT mechanism), which is particularly sensitive to oxygen. Oxygen removal is to protect the active groups of the chain transfer agent and the free radicals generated by the initiator, ensuring that the reaction proceeds along the designed path (i.e., the branching growth path).

[0085] The precursor liquid, after being thoroughly deoxygenated, eliminates inhibitory factors in the polymerization reaction, ensuring rapid initiation of the reaction during subsequent heating, more precise molecular weight control, and a more regular product structure.

[0086] Step S3: The pre-liquid after deoxygenation treatment is heated to carry out a free radical polymerization reaction.

[0087] This step is the core reaction step in the process. Operationally, the reaction vessel containing the precursor liquid can be placed in a heating device (such as an oil bath, water bath, or heating jacket), heated to the decomposition temperature of the initiator, and maintained for a certain period of time.

[0088] In this step, a complex cascade of chemical reactions occurs at the microscopic level: First, in the initiation stage, the thermal initiator decomposes to generate free radicals, which initiate monomer polymerization to form the main chain; then, in the copolymerization branching point introduction stage, the double bond ends of multifunctional chain transfer agents participate in polymerization as monomers, entering the main chain and giving the main chain "potential growth points"; finally, in the branched chain growth (RAFT process) stage, the growing free radicals attack chain transfer active groups (such as dithioester groups) on the main chain, undergoing a reversible addition-fragmentation chain transfer reaction, initiating the growth of new branched chains from the main chain.

[0089] The above processes occur simultaneously, ultimately forming a branched polymer solution with unique rheological properties on a macroscopic scale.

[0090] In this step, the reaction rate is controlled by temperature, so that the "main chain growth" and "branching reaction" proceed in synergy, and the target branched structure is synthesized in one step without the need for additional grafting steps.

[0091] Step S4: After the reaction is complete, the organic solvent and residual monomer are removed to obtain the continuously dissipating branched polymer pressure-sensitive adhesive.

[0092] In this step, the mixture after the reaction is complete is a polymer solution containing unreacted monomers and a large amount of solvent. This step is the process of converting the mixture into a pure pressure-sensitive adhesive product. Common methods to achieve this are vacuum drying (e.g., heating in a vacuum oven) or vacuum distillation.

[0093] It should be noted that pressure-sensitive adhesives, as viscoelastic materials, must be used in solvent-free bulk form. After solvent removal, the polymer molecular chains become entangled, forming an adhesive layer with a certain cohesive force. Residual monomers are usually toxic and odorous, and must be removed to meet application standards (especially in civilian or medical fields).

[0094] The final product obtained through this step is a solid (or semi-solid) viscous polymer material, namely the "continuously dissipative branched polymer pressure-sensitive adhesive" in this embodiment. This product can be used directly as an adhesive block, or coated onto a substrate before solvent removal and dried to form an adhesive tape.

[0095] In summary, this preparation method employs a one-pot free radical solution polymerization process. By mixing and dissolving monomers, initiators, and multifunctional chain transfer agents in an organic solvent, followed by deoxygenation and heating, a branched polymer structure with continuous energy dissipation capability can be efficiently constructed in one step. This method eliminates the need for complex stepwise grafting or post-processing crosslinking steps in traditional synthesis, simplifying the operation and providing mild and controllable reaction conditions, significantly reducing preparation difficulty and cost, making it suitable for large-scale industrial production. In terms of reaction mechanism, the precise construction of the polymer branched topology is achieved by accurately controlling the copolymerization and chain transfer processes of each component in a homogeneous precursor liquid. This specific branched structure allows the final pressure-sensitive adhesive material to maintain excellent wettability (rapid adhesion) while significantly improving interfacial toughness and adhesion strength through the continuous energy dissipation of branched chains during deformation, effectively solving the problem of balancing high adhesion energy and good wettability in existing technologies. Furthermore, the post-processing step removes solvents and residual monomers, ensuring the purity, safety, and environmental friendliness of the pressure-sensitive adhesive product.

[0096] In some embodiments, the deoxygenation treatment time is from 1 minute to 3 hours. For example, it can be 1 minute, 10 minutes, 30 minutes, 45 minutes, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, etc.

[0097] In some embodiments, the deoxygenation process is carried out by introducing nitrogen gas.

[0098] In this embodiment, before initiating polymerization, high-purity nitrogen gas (bubbling) is introduced into the reactor containing the precursor liquid for a duration controlled between 1 minute and 3 hours.

[0099] It should be noted that oxygen is a strong inhibitor of free radical polymerization. Oxygen dissolved in the solvent reacts rapidly with the primary free radicals released from the initiator to form stable peroxide free radicals, leading to a prolonged induction period or even preventing initiation. Introducing nitrogen gas utilizes the principle of partial pressure to physically displace the dissolved oxygen in the solution, creating an inert atmosphere.

[0100] In this implementation, the deoxygenation time (1 min to 3 h) depends on the volume of the reaction system. For small-scale laboratory synthesis, a shorter time is sufficient; for industrial-grade reactors, a longer time is required to ensure that the oxygen concentration drops below the threshold (typically <10 ppm).

[0101] In this embodiment, nitrogen gas is introduced for deoxygenation. Nitrogen is low-cost, chemically inert, and does not react with the reactants, making it the most economical and effective means of achieving inert protection. This ensures that the reaction is initiated according to the predetermined Reactive Radical Free Radical (RAFT) mechanism, reducing the formation of dead chains and guaranteeing the accurate construction of branched structures.

[0102] In some embodiments, the temperature of the free radical polymerization reaction is 40°C to 110°C. For example, it can be 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, etc.

[0103] In some embodiments, the reaction time of the free radical polymerization reaction is 1 h to 72 h. For example, it can be 1 h, 6 h, 12 h, 24 h, 36 h, 48 h, 50 h, 60 h, 72 h, etc.

[0104] In this embodiment, the reaction system is heated and maintained in a constant temperature environment of 40°C to 110°C for 1 hour to 72 hours.

[0105] The temperature range (40~110℃) is matched to the half-life temperature of the thermal initiators listed in the foregoing embodiments (such as azobisisobutyronitrile (AIBN), benzoyl peroxide (BPO), etc.). If the temperature is too low (<40℃), the initiator decomposes too slowly, and polymerization cannot proceed effectively; if the temperature is too high (>110℃), the initiator decomposes too quickly ("burst polymerization"), generating a large amount of heat that is difficult to remove, and easily leading to solvent boiling or deactivation of the chain transfer agent.

[0106] It should be noted that polymerization is a time-dependent kinetic process. Sufficient time ensures high monomer conversion and reduces residue. For the "branching" process in this application, sufficient time allows the branched chains to grow to the designed length, thereby endowing the material with ideal dissipation capabilities.

[0107] Under preferred conditions (such as reaction at 60°C for 24 hours in the examples), a polymer solution with high conversion rate, moderate molecular weight distribution, and regular branching structure can be obtained.

[0108] In some embodiments, the step of removing the organic solvent and residual monomer includes drying for 3 h to 24 h (e.g., 0.1 Pa to 1000 Pa, such as 0.1 Pa, 1 Pa, 10 Pa, 50 Pa, 100 Pa, 200 Pa, 500 Pa, 800 Pa, 1000 Pa, etc.) at a vacuum of 0.1 Pa to 1000 Pa (e.g., 0.1 Pa, 1 Pa, 10 Pa, 100 Pa, 100 Pa, 110 Pa, 120 Pa, 130 Pa, 140 Pa, 150 Pa, etc.) and a temperature of 20 °C to 150 °C (e.g., 20 °C, 40 °C, 60 °C, 80 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, etc.).

[0109] This step involves the purification and solidification of the product. Typically, the polymer solution is coated or placed in a container and then processed in a vacuum oven or using a devolatilization device.

[0110] In the aforementioned vacuum distillation / drying process, the vacuum (0.1-1000 Pa) significantly lowers the boiling points of the solvent and monomer, allowing them to volatilize at lower temperatures. During the thermal diffusion stage, heating (20-150℃) provides energy for molecular thermal motion, accelerating the diffusion of solvent molecules from the entanglement of polymer chain segments.

[0111] It should be noted that high vacuum helps remove trace amounts of non-volatile monomers (such as some high-boiling-point monomers). Regarding temperature limits, the upper limit of 150°C is to prevent thermal degradation or oxidative crosslinking of the polymer; the lower limit of 20°C is suitable for the initial removal of low-boiling-point solvents. In terms of time, 3-24 hours ensures thorough drying to avoid residual small molecules affecting the cohesive strength of the pressure-sensitive adhesive and skin safety (if used for medical purposes).

[0112] This application also provides a pressure-sensitive adhesive product, including a substrate and a pressure-sensitive adhesive layer disposed on at least one surface of the substrate; wherein the pressure-sensitive adhesive layer comprises a continuously dissipating branched polymer pressure-sensitive adhesive as described in any of the foregoing embodiments.

[0113] The pressure-sensitive adhesive product provided in this application has a structural basis including a substrate and the aforementioned continuously dissipating branched polymer pressure-sensitive adhesive layer attached to the surface of the substrate. Depending on the substrate type and coating method, this product can cover a variety of practical applications. Specifically, this product includes, but is not limited to: single-sided tape, double-sided tape, foam tape, high-temperature protective film, optically transparent film (OCA), medical pressure-sensitive adhesive patches (such as bandages, electrode patches), label paper, advertising film, and encapsulation films for electronic components. The substrate can be diverse, including plastic films such as polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), and polyimide (PI), or materials such as paper, metal foil, non-woven fabric, and foam.

[0114] This application also provides the use of a multifunctional chain transfer agent in the preparation of a continuously dissipating branched polymer pressure-sensitive adhesive as described in any of the foregoing embodiments, wherein the multifunctional chain transfer agent is a compound comprising at least one chain transfer active group and at least one free radical polymerizable olefinic unsaturated group.

[0115] In the above applications, "multifunctional chain transfer agent" can refer to a specific compound that simultaneously possesses "chain transfer active groups" (such as dithioester groups) and "polymerizable groups" (such as double bonds). "Preparation of continuously dissipative branched polymer pressure-sensitive adhesives" means that the compound is no longer used merely as a common molecular weight regulator, but as a key structural unit for constructing specific branched topologies, used to synthesize a high-performance pressure-sensitive adhesive material.

[0116] This application imbues known or newly synthesized chain transfer agents with new industrial value. Compared to traditional physical crosslinking using multifunctional monomers (crosslinking agents), this chain transfer agent enables "active branching," that is, precise control of branching points and chain lengths during polymerization, thereby preparing pressure-sensitive adhesives with both high adhesion and excellent wettability, solving the problems of crosslinking embrittlement or poor wettability in traditional methods.

[0117] In this application embodiment, the use of the continuously dissipating branched polymer pressure-sensitive adhesive as described in any of the foregoing embodiments in the preparation of pressure-sensitive tapes, pressure-sensitive sheets or protective films is also provided.

[0118] In this embodiment, the "continuously dissipative branched polymer pressure-sensitive adhesive" provided in the aforementioned embodiments is the main body, and the object is "preparation of pressure-sensitive tape, pressure-sensitive film or protective film", which specifically refers to the process of using the pressure-sensitive adhesive as an intermediate material to process it into the final product.

[0119] Applications for this product include, but are not limited to, tape manufacturing, electronic material processing, and packaging material production. Due to its extremely high interfacial toughness (strong adhesion) and rapid wetting ability (fast adhesion), tapes or protective films made from this adhesive can withstand more demanding environments (such as heavy-duty, rough surface bonding), and offer high application efficiency without requiring prolonged pressure holding.

[0120] Specifically, a coating process can be used to uniformly coat a pressure-sensitive adhesive precursor solution containing solvent onto a substrate (backing) such as PET or PE. After drying in an oven to remove the solvent, the product can be rewound or cut to obtain tape, film, or protective film.

[0121] This application also provides an example of the use of a continuously dissipating branched polymer pressure-sensitive adhesive as described in any of the foregoing embodiments in bonding glass, plastic, or metal substrates.

[0122] In the above-mentioned applications, the high-performance pressure-sensitive adhesive described in this application is the main body, and "adhesion to glass, plastic or metal substrates" is the object, which refers to the functional behavior of the pressure-sensitive adhesive in actual end use.

[0123] Its applications can include, but are not limited to, consumer electronics assembly (bonding screen glass and metal casing), automotive interior fixing (bonding plastic parts), and daily office and packaging.

[0124] It should be noted that although "glass, plastic and metal" are mentioned in this embodiment, in actual applications, this pressure-sensitive adhesive, due to its excellent wettability, is also applicable (but not limited to) a variety of high-energy or low-energy surfaces such as wood, ceramics and paper.

[0125] For glass / metal (high-energy surfaces), the technology provided in this embodiment can establish extremely strong interfacial interactions, providing ultra-high adhesion (e.g., adhesion energy on glass > 6000 J / m). 2 For plastics (low-energy surfaces), the flexibility of the branched chains allows for rapid spreading and wetting, ensuring a long-lasting adhesive effect.

[0126] The present invention will be further illustrated below with specific embodiments. However, it should be understood that these embodiments are merely for the purpose of more detailed illustration and should not be construed as limiting the present invention in any way.

[0127] Example 1 This embodiment prepares a continuously dissipative branched polymer pressure-sensitive adhesive with a chain transfer agent to monomer molar ratio of 1:100.

[0128] Experimental methods: (1) Solution preparation: 18.00g butyl methacrylate (monomer 1, BA), 2.53g acrylic acid (monomer 2, AA), 0.906g 2-(methacryloyloxy)ethyl-4-cyano-4-(dodecylthiocarbonyl)thioalkylvalerate (multifunctional chain transfer agent), 0.143g azobisisobutyronitrile (initiator) and 22.5mL dioxane (solvent) were added sequentially to a round-bottom flask and stirred thoroughly until homogeneous to form a precursor solution.

[0129] (2) Deoxygenation: Nitrogen gas is introduced into the flask containing the precursor liquid and stirred continuously. After 30 minutes, the nitrogen gas is stopped and the reaction system is sealed.

[0130] (3) Polymerization: Immerse the flask in an oil bath at 60°C and react for 24 hours.

[0131] (4) Post-processing: After the reaction is complete, the product is coated on the surface of a plastic film and then placed in a vacuum drying oven at 110°C for 12 hours to remove the solvent and residual volatile monomers, thus obtaining the finished product.

[0132] Example 2 This embodiment prepares a continuously dissipative branched polymer pressure-sensitive adhesive with a chain transfer agent to monomer molar ratio of 1:200.

[0133] Experimental methods: (1) Solution preparation: 18.00g butyl methacrylate (monomer 1, BA), 2.53g acrylic acid (monomer 2, AA), 0.453g 2-(methacryloyloxy)ethyl-4-cyano-4-(dodecylthiocarbonyl)thioalkylvalerate (multifunctional chain transfer agent), 0.071g azobisisobutyronitrile (initiator) and 22.5mL dioxane (solvent) were added sequentially to a round-bottom flask and stirred thoroughly until homogeneous to form a precursor solution.

[0134] (2) Deoxygenation: Nitrogen gas is introduced into the flask containing the precursor liquid and stirred continuously. After 30 minutes, the nitrogen gas is stopped and the reaction system is sealed.

[0135] (3) Polymerization: Immerse the flask in an oil bath at 60°C and react for 24 hours.

[0136] (4) Post-processing: After the reaction is complete, the product is coated on the surface of a plastic film and then placed in a vacuum drying oven at 110°C for 12 hours to remove the solvent and residual volatile monomers, thus obtaining the finished product.

[0137] Example 3 This embodiment prepares a continuously dissipative branched polymer pressure-sensitive adhesive with a chain transfer agent to monomer molar ratio of 1:500.

[0138] Experimental methods: (1) Solution preparation: 18.00g butyl methacrylate (monomer 1, BA), 2.53g acrylic acid (monomer 2, AA), 0.181g 2-(methacryloyloxy)ethyl-4-cyano-4-(dodecylthiocarbonyl)thioalkylvalerate (multifunctional chain transfer agent), 0.029g azobisisobutyronitrile (initiator) and 22.5mL dioxane (solvent) were added sequentially to a round-bottom flask and stirred thoroughly until homogeneous to form a precursor solution.

[0139] (2) Deoxygenation: Nitrogen gas is introduced into the flask containing the precursor liquid and stirred continuously. After 30 minutes, the nitrogen gas is stopped and the reaction system is sealed.

[0140] (3) Polymerization: Immerse the flask in an oil bath at 60°C and react for 24 hours.

[0141] (4) Post-processing: After the reaction is complete, the product is coated on the surface of a plastic film and then placed in a vacuum drying oven at 110°C for 12 hours to remove the solvent and residual volatile monomers, thus obtaining the finished product.

[0142] Example 4 This embodiment prepares an optimal continuously dissipative branched polymer pressure-sensitive adhesive with a chain transfer agent to monomer molar ratio of 1:1000.

[0143] Experimental methods: (1) Solution preparation: 18.00g butyl methacrylate (monomer 1, BA), 2.53g acrylic acid (monomer 2, AA), 0.090g 2-(methacryloyloxy)ethyl-4-cyano-4-(dodecylthiocarbonyl)thioalkylvalerate (multifunctional chain transfer agent), 0.014g azobisisobutyronitrile (initiator) and 22.5mL dioxane (solvent) were added sequentially to a round-bottom flask and stirred thoroughly until homogeneous to form a precursor solution.

[0144] (2) Deoxygenation: Nitrogen gas is introduced into the flask containing the precursor liquid and stirred continuously. After 30 minutes, the nitrogen gas is stopped and the reaction system is sealed.

[0145] (3) Polymerization: Immerse the flask in an oil bath at 60°C and react for 24 hours.

[0146] (4) Post-processing: After the reaction is complete, the product is coated on the surface of a plastic film and then placed in a vacuum drying oven at 110°C for 12 hours to remove the solvent and residual volatile monomers, thus obtaining the finished product.

[0147] Example 5 This embodiment prepares a continuously dissipative branched polymer pressure-sensitive adhesive with a chain transfer agent to monomer molar ratio of 1:2000.

[0148] Experimental methods: (1) Solution preparation: 18.00g butyl methacrylate (monomer 1, BA), 2.53g acrylic acid (monomer 2, AA), 0.045g 2-(methacryloyloxy)ethyl-4-cyano-4-(dodecylthiocarbonyl)thioalkylvalerate (multifunctional chain transfer agent), 0.007g azobisisobutyronitrile (initiator) and 22.5mL dioxane (solvent) were added sequentially to a round-bottom flask and stirred thoroughly until homogeneous to form a precursor solution.

[0149] (2) Deoxygenation: Nitrogen gas is introduced into the flask containing the precursor liquid and stirred continuously. After 30 minutes, the nitrogen gas is stopped and the reaction system is sealed.

[0150] (3) Polymerization: Immerse the flask in an oil bath at 60°C and react for 24 hours.

[0151] (4) Post-processing: After the reaction is complete, the product is coated on the surface of a plastic film and then placed in a vacuum drying oven at 110°C for 12 hours to remove the solvent and residual volatile monomers, thus obtaining the finished product.

[0152] Example 6 This embodiment prepares a continuously dissipative branched polymer pressure-sensitive adhesive using a specific thiobenzoyl thio-based multifunctional chain transfer agent.

[0153] Experimental methods: (1) Solution preparation: 18.00g butyl methacrylate (monomer 1, BA), 2.53g acrylic acid (monomer 2, AA), 0.058g vinyl 4-cyano-4-(thiobenzoylthio)valerate (multifunctional chain transfer agent), 0.014g azobisisobutyronitrile (initiator) and 22.5mL dioxane (solvent) were added to a round-bottom flask in sequence and stirred thoroughly until homogeneous to form a precursor solution.

[0154] (2) Deoxygenation: Nitrogen gas is introduced into the flask containing the precursor liquid and stirred continuously. After 30 minutes, the nitrogen gas is stopped and the reaction system is sealed.

[0155] (3) Polymerization: Immerse the flask in an oil bath at 60°C and react for 24 hours.

[0156] (4) Post-processing: After the reaction is complete, the product is coated on the surface of a plastic film and then placed in a vacuum drying oven at 110°C for 12 hours to remove the solvent and residual volatile monomers, thus obtaining the finished product.

[0157] Example 7 This embodiment prepares a continuously dissipating branched polymer pressure-sensitive adhesive using a specific trithiocarbonate-based multifunctional chain transfer agent.

[0158] Experimental methods: (1) Solution preparation: 18.00g butyl methacrylate (monomer 1, BA), 2.53g acrylic acid (monomer 2, AA), 0.076g 2-(dodecyl trithiocarbonate) ethyl methacrylate (multifunctional chain transfer agent), 0.014g azobisisobutyronitrile (initiator) and 22.5mL dioxane (solvent) were added to a round-bottom flask in sequence and stirred thoroughly until homogeneous to form a precursor solution.

[0159] (2) Deoxygenation: Nitrogen gas is introduced into the flask containing the precursor liquid and stirred continuously. After 30 minutes, the nitrogen gas is stopped and the reaction system is sealed.

[0160] (3) Polymerization: Immerse the flask in an oil bath at 60°C and react for 24 hours.

[0161] (4) Post-processing: After the reaction is complete, the product is coated on the surface of a plastic film and then placed in a vacuum drying oven at 110°C for 12 hours to remove the solvent and residual volatile monomers, thus obtaining the finished product.

[0162] Example 8 This embodiment prepares a continuously dissipating branched polymer pressure-sensitive adhesive using a specific dithiobenzoic acid ester-based multifunctional chain transfer agent.

[0163] Experimental methods: (1) Solution preparation: 18.00g butyl methacrylate (monomer 1, BA), 2.53g acrylic acid (monomer 2, AA), 0.067g benzyl-3-(methacryloyloxy)propyl dithiobenzoate (multifunctional chain transfer agent), 0.014g azobisisobutyronitrile (initiator) and 22.5mL dioxane (solvent) were added to a round-bottom flask in sequence and stirred thoroughly until homogeneous to form a precursor solution.

[0164] (2) Deoxygenation: Nitrogen gas is introduced into the flask containing the precursor liquid and stirred continuously. After 30 minutes, the nitrogen gas is stopped and the reaction system is sealed.

[0165] (3) Polymerization: Immerse the flask in an oil bath at 60°C and react for 24 hours.

[0166] (4) Post-processing: After the reaction is complete, the product is coated on the surface of a plastic film and then placed in a vacuum drying oven at 110°C for 12 hours to remove the solvent and residual volatile monomers, thus obtaining the finished product.

[0167] Comparative Example 1 (weak hydrogen bond) This comparative example prepared a weakly hydrogen-branched polymer pressure-sensitive adhesive with a low acrylic acid content.

[0168] Experimental methods: (1) Solution preparation: 20.25g butyl methacrylate (monomer 1, BA), 1.27g acrylic acid (monomer 2, AA), 0.090g 2-(methacryloyloxy)ethyl-4-cyano-4-(dodecylthiocarbonyl)thioalkylvalerate (multifunctional chain transfer agent), 0.014g azobisisobutyronitrile (initiator) and 24.0mL dioxane (solvent) were added sequentially to a round-bottom flask and stirred thoroughly until homogeneous to form a precursor solution.

[0169] (2) Deoxygenation: Nitrogen gas is introduced into the flask containing the precursor liquid and stirred continuously. After 30 minutes, the nitrogen gas is stopped and the reaction system is sealed.

[0170] (3) Polymerization: Immerse the flask in an oil bath at 60°C and react for 24 hours.

[0171] (4) Post-processing: After the reaction is complete, the product is coated on the surface of a plastic film and then placed in a vacuum drying oven at 110°C for 12 hours to remove the solvent and residual volatile monomers, thus obtaining the finished product.

[0172] Comparative Example 2 (hydrogen-rich) This comparative example prepared a hydrogen-rich branched polymer pressure-sensitive adhesive with high acrylic acid content.

[0173] Experimental methods: (1) Solution preparation: 15.75g butyl methacrylate (monomer 1, BA), 3.80g acrylic acid (monomer 2, AA), 0.090g 2-(methacryloyloxy)ethyl-4-cyano-4-(dodecylthiocarbonyl)thioalkylvalerate (multifunctional chain transfer agent), 0.014g azobisisobutyronitrile (initiator) and 21.3mL dioxane (solvent) were added sequentially to a round-bottom flask and stirred thoroughly until homogeneous to form a precursor solution.

[0174] (2) Deoxygenation: Nitrogen gas is introduced into the flask containing the precursor liquid and stirred continuously. After 30 minutes, the nitrogen gas is stopped and the reaction system is sealed.

[0175] (3) Polymerization: Immerse the flask in an oil bath at 60°C and react for 24 hours.

[0176] (4) Post-processing: After the reaction is complete, the product is coated on the surface of a plastic film and then placed in a vacuum drying oven at 110°C for 12 hours to remove the solvent and residual volatile monomers, thus obtaining the finished product.

[0177] Comparative Example 3 (Linear) This comparative example prepared a common linear polymer pressure-sensitive adhesive with a chain transfer agent to monomer molar ratio of 1:500.

[0178] Experimental methods: (1) Solution preparation: 18.00g butyl methacrylate (monomer 1, BA), 2.53g acrylic acid (monomer 2, AA), 0.181g 4-cyano-4-(dodecylthiothiocarbonyl)thioalkylvalerate (monofunctional chain transfer agent), 0.029g azobisisobutyronitrile (initiator) and 22.5mL dioxane (solvent) were added sequentially to a round-bottom flask and stirred thoroughly until homogeneous to form a precursor solution.

[0179] (2) Deoxygenation: Nitrogen gas is introduced into the flask containing the precursor liquid and stirred continuously. After 30 minutes, the nitrogen gas is stopped and the reaction system is sealed.

[0180] (3) Polymerization: Immerse the flask in an oil bath at 60°C and react for 24 hours.

[0181] (4) Post-processing: After the reaction is complete, the product is coated on the surface of a plastic film and then placed in a vacuum drying oven at 110°C for 12 hours to remove the solvent and residual volatile monomers, thus obtaining the finished product.

[0182] Comparative Example 4 (Linear) This comparative example prepared a common linear polymer pressure-sensitive adhesive with a chain transfer agent to monomer molar ratio of 1:1000.

[0183] Experimental methods: (1) Solution preparation: 18.00g butyl methacrylate (monomer 1, BA), 2.53g acrylic acid (monomer 2, AA), 0.071g 4-cyano-4-(dodecylthiothiocarbonyl)thioalkylvalerate (monofunctional chain transfer agent), 0.014g azobisisobutyronitrile (initiator) and 22.5mL dioxane (solvent) were added sequentially to a round-bottom flask and stirred thoroughly until homogeneous to form a precursor solution.

[0184] (2) Deoxygenation: Nitrogen gas is introduced into the flask containing the precursor liquid and stirred continuously. After 30 minutes, the nitrogen gas is stopped and the reaction system is sealed.

[0185] (3) Polymerization: Immerse the flask in an oil bath at 60°C and react for 24 hours.

[0186] (4) Post-processing: After the reaction is complete, the product is coated on the surface of a plastic film and then placed in a vacuum drying oven at 110°C for 12 hours to remove the solvent and residual volatile monomers, thus obtaining the finished product.

[0187] Comparative Example 5 (Linear) This comparative example prepared a common linear polymer pressure-sensitive adhesive with a chain transfer agent to monomer molar ratio of 1:1250.

[0188] Experimental methods: (1) Solution preparation: 18.00g butyl methacrylate (monomer 1, BA), 2.53g acrylic acid (monomer 2, AA), 0.057g 4-cyano-4-(dodecylthiothiocarbonyl)thioalkylvalerate (monofunctional chain transfer agent), 0.011g azobisisobutyronitrile (initiator) and 22.5mL dioxane (solvent) were added sequentially to a round-bottom flask and stirred thoroughly until homogeneous to form a precursor solution.

[0189] (2) Deoxygenation: Nitrogen gas is introduced into the flask containing the precursor liquid and stirred continuously. After 30 minutes, the nitrogen gas is stopped and the reaction system is sealed.

[0190] (3) Polymerization: Immerse the flask in an oil bath at 60°C and react for 24 hours.

[0191] (4) Post-processing: After the reaction is complete, the product is coated on the surface of a plastic film and then placed in a vacuum drying oven at 110°C for 12 hours to remove the solvent and residual volatile monomers, thus obtaining the finished product.

[0192] Comparative Example 6 (Linear) This comparative example prepared a common linear polymer pressure-sensitive adhesive with a chain transfer agent to monomer molar ratio of 1:2000.

[0193] Experimental methods: (1) Solution preparation: 18.00g butyl methacrylate (monomer 1, BA), 2.53g acrylic acid (monomer 2, AA), 0.036g 4-cyano-4-(dodecylthiothiocarbonyl)thioalkylvalerate (monofunctional chain transfer agent), 0.007g azobisisobutyronitrile (initiator) and 22.5mL dioxane (solvent) were added sequentially to a round-bottom flask and stirred thoroughly until homogeneous to form a precursor solution.

[0194] (2) Deoxygenation: Nitrogen gas is introduced into the flask containing the precursor liquid and stirred continuously. After 30 minutes, the nitrogen gas is stopped and the reaction system is sealed.

[0195] (3) Polymerization: Immerse the flask in an oil bath at 60°C and react for 24 hours.

[0196] (4) Post-processing: After the reaction is complete, the product is coated on the surface of a plastic film and then placed in a vacuum drying oven at 110°C for 12 hours to remove the solvent and residual volatile monomers, thus obtaining the finished product.

[0197] Table 1. Summary of parameters for examples and comparative examples

[0198] Table 1 describes the types of chain transfer agents: Multifunctional CTA-1: 2-(methacryloyloxy)ethyl-4-cyano-4-(dodecylthiocarbonyl)thioalkyl valerate; Multifunctional CTA-2: 4-cyano-4-(thiobenzoylthio)pentanoic acid vinyl ester; Multifunctional CTA-3: 2-(dodecyl trithiocarbonate)ethyl methacrylate; Multifunctional CTA-4: benzyl-3-(methacryloyloxy)propyl dithiobenzoate; Monofunctional CTA: 4-cyano-4-(dodecylthiocarbonyl)thioalkyl valerate (does not contain double bonds, only forms a linear structure).

[0199] Test Experiment 1. Testing method: After all the examples and comparative examples were prepared, the properties of the pressure-sensitive adhesives were characterized mainly by the following methods: (1) 90-degree peel test (main test): Reference standards: ASTM D6862 and ASTM D3330.

[0200] Test substrate: Glass substrate.

[0201] Sample preparation steps: Attach the material to the surface of the glass substrate, press it back and forth twice with a 2kg roller force, and let it stand for 30 minutes to relax the residual stress.

[0202] Test conditions: peeling speed is constant at 100 mm / min.

[0203] Data recording: Real-time recording of material displacement and stress (force-displacement curve).

[0204] (2) Probe adhesion test: used to characterize the rapid adhesion (wetting) ability of materials and record the change of adhesion force over time.

[0205] (3) Rheological testing: Frequency scanning is performed to obtain the master rheological curve, which is used to analyze the modulus and dissipation mechanism of the material.

[0206] 2. Experimental Results and Analysis: (1) Effect of hydrogen bond content on the performance of pressure-sensitive adhesive (comparative analysis): Table 2. Results of the investigation on the effect of hydrogen bond content on the performance of pressure-sensitive adhesives

[0207] By comparison Figure 1 and Figure 2 The results show that simply adjusting the content of acrylic acid (AA) monomer (i.e., adjusting the hydrogen bond strength) is insufficient to simultaneously achieve high toughness and good wettability. In Comparative Example 1 (weak hydrogen bonds), although the peel curve was complete, the interfacial toughness was low due to the weak interaction forces. In Comparative Example 2 (rich hydrogen bonds), although a large number of hydrogen bonds were introduced to attempt to enhance dissipation, the excessively strong hydrogen bond network caused hardening of the molecular chain segment regions, significantly reducing the wettability of the material, resulting in poor contact with the substrate interface, and even making it impossible to measure a complete peel curve. This confirms the defect of existing technologies relying on non-covalent bonds (hydrogen bonds) for reinforcement, where "high adhesion energy and wettability are mutually restrained."

[0208] (2) Performance comparison between branched polymers (this application) and linear polymers: 1) Branched polymer group (example): The variable is the molar ratio of chain transfer agent to monomer (1:100 to 1:2000).

[0209] Table 3. Comparison of Branched Polymer Groups (Examples)

[0210] Figures 3-7 The exfoliation behavior of Examples 1-5 under different molar ratios of chain transfer agent to monomer is demonstrated. The results show that all branched samples incorporating multifunctional chain transfer agents exhibit complete exfoliation curves and high interfacial toughness.

[0211] It is worth noting that the interfacial toughness first increases and then decreases with the change of molar ratio. At a molar ratio of 1:1000 (Example 4), the toughness decreases. Figure 6 The integral area under the force-displacement curve is the largest, and the interfacial toughness reaches its highest value (6164 J / m).2 This indicates that the amount of multifunctional chain transfer agent has a significant impact on the construction and final performance of the branched structure, and there exists an optimal ratio window that can maximize the energy dissipation capacity.

[0212] 2) Linear polymer group (comparative example): The variable is the molar ratio of chain transfer agent to monomer (1:500 to 1:2000).

[0213] Table 4. Comparison of linear polymer groups (comparative examples)

[0214] Figures 8-11 The exfoliation behavior of linear polymers prepared using monofunctional chain transfer agents is demonstrated. Compared to branched samples (examples) at the same molar ratio, the linear samples generally exhibit lower interfacial toughness. For example, Figure 9 The (linear, 1:1000) toughness is significantly lower than that of [other components]. Figure 6 (Branching, 1:1000). Furthermore, the linear sample reached its peak performance at a molar ratio of 1:1250, but this peak still could not match the optimal performance of the branched sample. This indicates that, under the same chemical composition, the polymer's topology (linear vs. branched) is the key factor determining interfacial toughness.

[0215] 3) Comprehensive comparative analysis (branched vs. linear): Table 5. Comprehensive Comparative Analysis

[0216] Figure 12 The interfacial toughness of samples with different molecular weights was summarized. The results clearly show that in the low molecular weight region, the performance difference between branched and linear samples is not significant; however, in the high molecular weight region, the interfacial toughness of the example (branched) is significantly higher than that of the comparative example (linear), which reflects the unique advantages of the branched structure in terms of macromolecular chain entanglement and dissipation.

[0217] Figure 13 The actual stress-strain behavior of Example 4 and Comparative Example 6 was further compared. Although their elastic moduli were very close (0.24 MPa and 0.22 MPa, respectively), indicating that branching did not lead to material "hardening," Example 4 exhibited a broad and stable stress plateau after the yield point, while the stress in Comparative Example 6 decayed rapidly. This phenomenon directly confirms the core mechanism of the present invention: branched chains can slowly and continuously provide energy storage and release (i.e., continuous dissipation) during deformation, while linear chains cannot maintain this continuous resistance.

[0218] 3. Wettability, versatility, and literature comparison: Table 6. Comparison of wettability, versatility, and literature.

[0219] Figure 14 The probe adhesion test results showed that the adhesion force in Example 4 reached equilibrium within 30 seconds. Combined with... Figure 13 The low-to-medium modulus properties demonstrate that the branched pressure-sensitive adhesive of this invention maintains excellent flexibility and rapid wetting ability while possessing ultra-high interfacial toughness, successfully resolving the contradiction between "strong adhesion" and "fast adhesion".

[0220] Figure 15 This paper presents a comparison of the preferred embodiment 4 of the present invention with typical pressure-sensitive adhesives reported in the prior art in terms of initial tack and interfacial toughness. The sources of prior art literature used for comparison are listed in detail in Table 7 below. Figure 15 It can be seen that the data points of existing technologies are often concentrated in areas with high initial tack but low toughness, or high toughness but low initial tack, making it difficult to balance both. However, the data points of Embodiment 4 of this invention are located in the advantageous region of the coordinate system (upper right corner), indicating that it has excellent performance in both the initial tack (representing rapid wetting ability) and interfacial toughness (representing adhesion strength), successfully breaking through the performance bottleneck of the mutual restraint between the two in existing pressure-sensitive adhesive materials.

[0221] Table 7 Figure 15 List of existing technical documents used for comparison

[0222] also, Figure 16 The results show that when different types of multifunctional chain transfer agents (such as those in Examples 6-8) are used, the pressure-sensitive adhesives also exhibit excellent adhesion properties. This strongly demonstrates that the technical concept of "constructing a continuously dissipating branched structure using multifunctional chain transfer agents" proposed in this invention has good universality and is not limited to specific compounds.

[0223] 4. Rheological mechanism analysis: Table 8. Rheological Mechanism Analysis

[0224] Figure 17 and Figure 18The frequency-scan rheological master curves of Example 4 (branched) and Comparative Example 6 (linear) were compared. The results show that the two exhibit very similar performance in the high-frequency region (corresponding to rapid deformation or low-temperature behavior), but in the low-frequency region (corresponding to slow deformation or high-temperature / long-term behavior), the modulus of Example 4 is significantly higher than that of Comparative Example 6. The difference in rheological data explains the improvement in macroscopic performance from the perspective of microdynamics: although the introduction of branched chains did not significantly change the overall hardness of the material (the modulus did not increase dramatically across the entire length), it effectively introduced an energy dissipation mechanism in a wider frequency domain (especially in the low-frequency region), thereby achieving a significant improvement in interfacial toughness without sacrificing bulk flexibility.

[0225] 5. Discussion on conventional crosslinking systems: In the experiment, the inventors attempted to use a conventional method for constructing branched / crosslinked networks, namely, physically mixing and polymerizing equal amounts of a common chain transfer agent (such as dodecyl mercaptan, DDT) and a common multifunctional monomer (such as 1,6-hexanediol diacrylate, HDDA) in the same monomer system. The results showed that, because the binding of HDDA to the chain transfer agent is random and has a low probability, it is difficult to form an effective chemical association between the end groups formed by the common chain transfer agent and the crosslinking points formed by HDDA. This system is highly prone to uncontrollable gelation, and the final product often forms a rigid elastomer network with no adhesion, completely losing the initial tack and wettability required for pressure-sensitive adhesives, making it unsuitable for interfacial adhesion tests. This further confirms that the "multifunctional chain transfer agent with dual active groups" used in this application plays an irreplaceable key role in constructing specific "continuously dissipative branched structures." Through the synergistic effect of intramolecular bifunctionality, it achieves precise control over the polymer topology, which is unattainable with simple multi-component physical mixing.

[0226] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A continuously dissipating branched polymer pressure-sensitive adhesive, characterized in that, The continuously dissipating branched polymer pressure-sensitive adhesive is prepared by free radical polymerization of reactive raw materials including monomers, initiators and multifunctional chain transfer agents. The multifunctional chain transfer agent is a compound containing at least one chain transfer active group and at least one free radical polymerizable olefinic unsaturated group.

2. The continuously dissipating branched polymer pressure-sensitive adhesive as described in claim 1, characterized in that, The chain transfer active group includes at least one selected from dithioester, trithiocarbonate, dithiocarbamate, xanthate, organosulfonate, and organoselenoyl groups; and / or, The multifunctional chain transfer agent comprises at least one selected from 2-(methacryloyloxy)ethyl-4-cyano-4-(dodecylthiocarbonyl)thioalkylpentanoate, 2-(dodecyltrithiocarbonate)ethyl methacrylate, S-allyl-S′-(α,α′-dimethyl-α′′-acetic acid)trithiocarbonate, 2-(N,N-diethyldithiocarbamoyl)ethyl methacrylate, 4-cyano-4-(thiobenzoylthio)pentanoic acid vinyl ester, 2-(isopropylxanthyl)ethylacrylamide, and benzyl-3-(methacryloyloxy)propyl dithiobenzoate; and / or The initiator comprises at least one selected from azobisisobutyronitrile, azobisisovalerate, azobisisoheptanenitrile, dimethyl azobisisobutyrate, 1-(cyano-1-methylethylazo)formamide, 1,1'-azo(cyanocyclohexane), benzoyl peroxide, dicumyl peroxide, methyl ethyl ketone peroxide, di-tert-butyl peroxide, potassium persulfate, and ammonium persulfate; and / or, The monomer comprises at least one of acrylate monomers, acrylic monomers, acrylamide monomers, and vinyl monomers; or, the monomer comprises at least one of butyl methacrylate, hexafluorobutyl methacrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, phenyl methacrylate, benzyl methacrylate, isobornyl methacrylate, glycidyl methacrylate, methyl acrylate, cyclohexyl acrylate, benzyl acrylate, hydroxyethyl methacrylate, hydroxyethyl methacrylate, diethylaminoethyl methacrylate, acrylic acid, methacrylic acid, acrylamide, isoacrylate acrylamide, dimethylacrylamide, diethylacrylamide, hydroxyethylacrylamide, sodium vinyl sulfonate, vinyl glycol monoether, and styrene.

3. The continuously dissipating branched polymer pressure-sensitive adhesive as described in claim 1, characterized in that, The molar ratio of the multifunctional chain transfer agent to the monomer is 1:(100-10000); and / or, The molar ratio of the initiator to the multifunctional chain transfer agent is 1:(0.5-20).

4. The continuously dissipating branched polymer pressure-sensitive adhesive as described in claim 1, characterized in that, The reaction raw materials also include organic solvents; Preferably, the boiling point of the organic solvent is higher than the initiation temperature of the initiator; Preferably, the volume ratio of the organic solvent to the reactants (excluding the organic solvent) in the reaction raw materials is 1:(0.1-10); Preferably, the organic solvent includes at least one selected from dioxane, toluene, xylene, ethyl acetate, butyl acetate, butanone, methyl isobutyl ketone, cyclohexanone, N,N-dimethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide.

5. A method for preparing a continuously dissipating branched polymer pressure-sensitive adhesive as described in any one of claims 1-4, characterized in that, include: The reaction raw materials containing the monomer, the initiator and the multifunctional chain transfer agent are dissolved in an organic solvent to form a precursor liquid; The precursor fluid is subjected to deoxygenation treatment; The deoxygenated precursor liquid is heated to carry out a free radical polymerization reaction; After the reaction is complete, the organic solvent and residual monomers are removed to obtain the continuously dissipating branched polymer pressure-sensitive adhesive.

6. The method for preparing the continuously dissipating branched polymer pressure-sensitive adhesive as described in claim 5, characterized in that, The deoxygenation treatment time is 1 min to 3 h; and / or, The deoxygenation treatment is performed by introducing nitrogen gas; and / or, The free radical polymerization reaction is carried out at a temperature of 40℃ to 110℃; and / or, The reaction time for the free radical polymerization reaction is 1 h to 72 h; and / or, The step of removing the organic solvent and residual monomer includes drying for 3 to 24 hours under a vacuum of 0.1 Pa to 1000 Pa and a temperature of 20°C to 150°C.

7. A pressure-sensitive adhesive product, characterized in that, Includes a substrate and a pressure-sensitive adhesive layer disposed on at least one surface of the substrate; The pressure-sensitive adhesive layer comprises a continuously dissipating branched polymer pressure-sensitive adhesive as described in any one of claims 1-4.

8. The use of a multifunctional chain transfer agent in the preparation of a continuously dissipating branched polymer pressure-sensitive adhesive as described in any one of claims 1-4, characterized in that, The multifunctional chain transfer agent is a compound containing at least one chain transfer active group and at least one free radical polymerizable olefinic unsaturated group.

9. Use of a continuously dissipating branched polymer pressure-sensitive adhesive as described in any one of claims 1-4 in the preparation of pressure-sensitive tapes, pressure-sensitive sheets, or protective films.

10. Use of a continuously dissipating branched polymer pressure-sensitive adhesive as described in any one of claims 1-4 in bonding glass, plastic or metal substrates.

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