Bi-component polyurethane pouring sealant for packaging crystal film screen as well as preparation method and application of bi-component polyurethane pouring sealant

Abstract

The invention discloses a two-component polyurethane pouring sealant for packaging a crystal film screen as well as a preparation method and application of the two-component polyurethane pouring sealant, and relates to the technical field of adhesives. The bi-component polyurethane pouring sealant for packaging the crystal film screen comprises a component A and a component B, wherein the component A comprises polyether polyol and polyester polyol in parts by mass; the component B is prepared from a benzidine modified polyurethane prepolymer, an aromatic isocyanate modified epoxy resin prepolymer, a catalyst, an antioxidant, an ultraviolet light absorber, a defoaming agent, a wetting agent and a dispersing agent in parts by mass. According to the technical scheme, the benzidine modified polyurethane prepolymer with the symmetrical structure and the aromatic isocyanate modified epoxy resin prepolymer containing the benzene ring are added, crystallization is promoted and intermolecular hydrogen bonds are generated through the symmetrical structure, the cohesion of the polyurethane pouring sealant can be enhanced, and the adhesive force of the sealant and a base material is enhanced; and aromatic isocyanate containing benzene rings can enhance the overall molecular rigidity and further enhance cohesion.

Description

Technical Field

[0001] The present invention relates to the technical field of adhesives, and particularly relates to a two-component polyurethane potting adhesive for encapsulating crystal film screens, a preparation method thereof, and an application thereof. Background Art

[0002] LED transparent screens are transparent display products widely used in the market. The LED crystal film screen is a type of transparent screen, which has the characteristics of ultra-high transparency and ultra-thinness, and has received wide attention. Crystal film screens are mostly used in environments with glass, such as building glass curtain walls, glass display windows, glass guardrails, etc. The crystal film screen adopts the technology of directly planting bare LED lamp beads, and the lamp board uses a transparent crystal film film, with a transparent mesh circuit etched on the surface. After the components are pasted on the surface, a vacuum potting process is used. The product has the main advantages of being light, transparent, thin, bendable, and cuttable; it can be directly pasted on the glass curtain wall without damaging the original structure of the building; when not playing, the screen is invisible, does not affect indoor lighting, and when viewed from a distance, there is no sign of screen installation. The light transmittance of the crystal film screen is as high as 95%, which can present bright and beautiful image effects, making the images of the product more eye-catching, and the ultra-clear colors create an excellent visual experience for users.

[0003] The potting process of crystal film screens often uses potting adhesives. Currently, the commonly used potting adhesives in the market are two-component addition-type silicone potting adhesives or epoxy potting adhesives, which have problems such as poor adhesion between the glue and the substrate and poor cohesive force of the glue during use.

[0004] Therefore, there is still a need to develop a potting adhesive with good adhesion to the substrate and good cohesive force of the glue. Summary of the Invention

[0005] The main object of the present invention is to provide a two-component polyurethane potting adhesive for encapsulating crystal film screens, a preparation method thereof, and an application thereof, aiming to solve the problems of poor adhesion between the existing adhesives for encapsulating crystal film screens and the substrate and poor cohesive force of the glue.

[0006] To achieve the above object, the present invention provides a two-component polyurethane potting adhesive for encapsulating crystal film screens, and the two-component polyurethane potting adhesive for encapsulating crystal film screens includes component A and component B; wherein:

[0007] Component A includes, by mass: 30 - 60 parts of polyether polyol and 40 - 70 parts of polyester polyol;

[0008] Component B includes, by mass: 30 - 50 parts of benzidine-modified polyurethane prepolymer, 40 - 50 parts of aromatic isocyanate-modified epoxy resin prepolymer, 4 - 5 parts of catalyst, 3 - 5 parts of antioxidant, 1 - 2 parts of ultraviolet absorber, 1 - 2 parts of defoaming agent, 0.5 - 1 part of wetting agent, and 0.5 - 1 part of dispersant.

[0009] In one embodiment, the molecular weight of the benzidine-modified polyurethane prepolymer is 1000 to 3000; and / or,

[0010] the molecular weight of the aromatic isocyanate-modified epoxy resin prepolymer is 800 to 2000; and / or,

[0011] the aromatic isocyanate in the aromatic isocyanate-modified epoxy resin prepolymer includes at least one of toluene diisocyanate, diphenylmethane diisocyanate, and naphthalene 1,5-diisocyanate; and / or,

[0012] the initiator of the polyether polyol is glycerol; and / or,

[0013] the average functionality of the polyether polyol is 3 and the average molecular weight is 300 to 2000; and / or,

[0014] the initiator of the polyester polyol is phthalic acid; and / or,

[0015] the average functionality of the polyester polyol is 2 and the average molecular weight is 2000 to 5000; and / or,

[0016] the isocyanate includes hexamethylene diisocyanate or isophorone diisocyanate; and / or,

[0017] the catalyst includes an organotin catalyst, and the organotin catalyst includes organotin catalyst T12 or organotin catalyst T9.

[0018] In one embodiment, the benzidine-modified polyurethane prepolymer is prepared by the following steps:

[0019] Mix the polyether polyol and the diisocyanate, and carry out a first addition reaction to obtain a prepolymer;

[0020] Mix benzidine and an organic solvent to obtain a benzidine solution, and then mix the benzidine solution and the prepolymer to carry out a second addition reaction to obtain a benzidine-modified polyurethane prepolymer.

[0021] In one embodiment, the addition amounts of the polyether polyol and the diisocyanate are calculated according to the molar ratio of the hydroxyl groups of the polyether polyol to the isocyanate groups of the diisocyanate being 1:(2 to 3); and / or,

[0022] the addition amounts of the benzidine and the prepolymer are calculated according to the molar ratio of the amino groups of the benzidine to the isocyanate groups of the prepolymer being (2 to 3):1.

[0023] In one embodiment, the aromatic isocyanate-modified epoxy resin prepolymer is prepared by the following steps:

[0024] The epoxy resin, aromatic isocyanate and catalyst are mixed to carry out a third addition reaction to obtain an aromatic isocyanate-modified epoxy resin prepolymer.

[0025] In one embodiment, in the step of mixing the epoxy resin, aromatic isocyanate and catalyst to carry out a third addition reaction to obtain an aromatic isocyanate-modified epoxy resin prepolymer:

[0026] The addition amounts of the epoxy resin and aromatic isocyanate are calculated according to the molar ratio of the hydroxyl groups in the epoxy resin to the isocyanate groups in the aromatic isocyanate being 1:(1-1.2).

[0027] The present invention also provides a preparation method of the two-component polyurethane potting adhesive for crystal film screen encapsulation, and the preparation method includes the preparation of component A and the preparation of component B;

[0028] The preparation of component A includes: mixing a polyether polyol and a polyester polyol to obtain a first mixture, and dehydrating the first mixture to obtain component A;

[0029] The preparation of component B includes: mixing an antioxidant, a benzidine-modified polyurethane prepolymer and an aromatic isocyanate-modified epoxy resin prepolymer to obtain a second mixture, dehydrating the second mixture, and then mixing the dehydrated second mixture, a catalyst, an ultraviolet absorber, an antifoaming agent, a wetting agent and a dispersant to obtain component B.

[0030] The present invention also provides an application of the two-component polyurethane potting adhesive for crystal film screen encapsulation in crystal film screen encapsulation.

[0031] In one embodiment, the application of the two-component polyurethane potting adhesive for crystal film screen encapsulation in crystal film screen encapsulation includes the following steps:

[0032] Provide a crystal film screen, mix component A and component B according to a mass ratio of 100:(50-100) to obtain a two-component polyurethane potting adhesive for crystal film screen encapsulation, fill the two-component polyurethane potting adhesive for crystal film screen encapsulation at the bonding part to be bonded of the crystal film screen, and carry out curing.

[0033] In one embodiment, component A and component B are mixed at 15-40°C for 3-5 min; and / or,

[0034] After mixing component A and component B, it is filled at the bonding part to be bonded of the crystal film screen within 2-6 h; and / or,

[0035] The curing parameters are: the curing temperature is 20-30°C, and the curing time is 3-5 h.

[0036] In the technical solution of the present invention, an aromatic isocyanate-modified epoxy resin prepolymer is used to replace the conventional isocyanate, and a benzidine-modified polyurethane prepolymer is added. Among them, there is a rigid benzene ring structure in the aromatic isocyanate molecule, which can enhance the overall molecular rigidity, and at the same time contribute to the formation of stronger non-covalent interactions such as van der Waals forces and π-π interactions, so that the formed hard segment has higher cohesion, thereby enhancing the cohesion of the polyurethane potting adhesive and improving the bonding strength and durability of the polyurethane potting adhesive; the benzidine-modified polyurethane prepolymer has a symmetric structure and an amino structure. On the one hand, crystallization is promoted through the symmetric structure, which is beneficial to enhancing the cohesion of the polyurethane. On the other hand, taking advantage of the formation of intermolecular hydrogen bonds by the amino group, the cohesion and the adhesion of the polyurethane potting adhesive to the substrate are further enhanced. The two-component polyurethane potting adhesive provided by the present invention for crystal film screen encapsulation has good cohesion, strong adhesion to the substrate, and also has good light transmittance, high temperature and high humidity resistance, yellowing resistance and high and low temperature resistance, and can be used to solve the problems of poor adhesion to the substrate and poor cohesion of the glue existing in the existing adhesives for crystal film screen encapsulation, and meet the encapsulation requirements of crystal film screens. Specific embodiments

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0038] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present invention, the directional indications are only used to explain the relative position relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0039] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, such descriptions of "first", "second", etc. are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, if "and / or" or "and / or" appears throughout the text, its meaning includes three parallel scenarios. Taking "A and / or B" as an example, it includes scenario A, or scenario B, or the scenario where both A and B are satisfied simultaneously. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on what can be achieved by those of ordinary skill in the art. When the combination of technical solutions results in contradictions or cannot be achieved, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0040] LED transparent screens are transparent display products widely used in the market. The LED crystal film screen is a type of transparent screen with the characteristics of ultra-high transparency and ultra-thinness, and has received extensive attention. Crystal film screens are mostly used in environments with glass, such as building glass curtain walls, glass display windows, and glass guardrails. The crystal film screen adopts the technology of directly planting balls on the bare LED lamp beads. The lamp board uses a transparent crystal film film, with a transparent mesh circuit etched on the surface. After the components are pasted on the surface, a vacuum encapsulation process is used. The main advantages of the product are light, transparent, thin, bendable, and cuttable; it can be directly pasted on the glass curtain wall without damaging the original structure of the building; when not playing, the screen is invisible and does not affect the indoor lighting. When viewed from a distance, there is no sign of screen installation. The light transmittance of the crystal film screen is as high as 95%, and it can present bright and beautiful image effects, making the images of the product more eye-catching. The ultra-clear colors create an excellent visual experience for users.

[0041] The encapsulation process of crystal film screens often uses potting glue. Currently, two-component addition-type silicone potting glue or epoxy potting glue is mostly used for encapsulation in the market, and there are problems such as poor adhesion between the glue and the substrate and poor cohesive force of the glue. Therefore, there is still a need to develop a potting glue with good adhesion to the substrate and good cohesive force of the glue.

[0042] Polyurethane adhesives refer to adhesives containing urethane groups (-NHCOO-) or isocyanate groups (-NCO) in the molecular chain, showing high activity and polarity. Polyurethane adhesives have excellent chemical adhesion to substrates containing active hydrogen, such as porous materials like foam, plastic, wood, leather, fabric, paper, ceramics, etc., and smooth-surface materials like metal, glass, rubber, and plastic. Polyurethane adhesives have excellent flexibility, impact resistance, chemical resistance, and wear resistance.

[0043] Based on the above background, the present invention proposes a two-component polyurethane potting glue for crystal film screen encapsulation. The two-component polyurethane potting glue for crystal film screen encapsulation includes component A and component B; wherein:

[0044] The component A includes, by mass parts: 30 - 60 parts of polyether polyol and 40 - 70 parts of polyester polyol;

[0045] The component B includes, by mass parts: 30 - 50 parts of benzidine - modified polyurethane prepolymer, 40 - 50 parts of aromatic isocyanate - modified epoxy resin prepolymer, 4 - 5 parts of catalyst, 3 - 5 parts of antioxidant, 1 - 2 parts of ultraviolet absorber, 1 - 2 parts of defoamer, 0.5 - 1 part of wetting agent and 0.5 - 1 part of dispersant.

[0046] In the technical solution of the present invention, aromatic isocyanate - modified epoxy resin prepolymer is used to replace conventional isocyanate, and benzidine - modified polyurethane prepolymer is added. Among them, due to the presence of a rigid benzene ring structure in the aromatic isocyanate, the overall molecular rigidity can be enhanced. At the same time, it helps to form stronger non - covalent interactions such as van der Waals forces and π - π interactions, so that the formed hard segment has higher cohesion, thereby enhancing the cohesion of the polyurethane potting adhesive. The benzidine - modified polyurethane prepolymer has a symmetric structure and an amino structure. On the one hand, the symmetric structure promotes crystallization, which is beneficial to enhancing the cohesion of polyurethane. On the other hand, taking advantage of the formation of intermolecular hydrogen bonds by the amino group, the cohesion is further enhanced, and at the same time, the adhesion between the polyurethane potting adhesive and the substrate is enhanced. Therefore, the two - component polyurethane potting adhesive for crystal film screen encapsulation provided by the present invention has good cohesion, strong adhesion to the substrate, and good light transmittance, high - temperature and high - humidity resistance, yellowing resistance and high - and low - temperature resistance, which can meet the encapsulation requirements of the crystal film screen. In addition, in the technical solution of the present invention, antioxidants are used to inhibit the oxidation of methylene in the thermal oxidation process and delay the yellowing process. Ultraviolet absorbers are used to absorb or transfer ultraviolet energy and reduce the photodegradation reaction. The compound use of ultraviolet absorbers and antioxidants can synergistically improve the yellowing resistance effect. Defoamers are used to effectively remove or prevent the generation of foam, which helps to improve the appearance quality and mechanical properties of the product. Wetting agents are used to reduce the surface tension at the liquid - solid interface, making the liquid easier to spread and evenly cover the surface of the substrate, enhancing the adhesion and flatness of the coating. Dispersants are used to evenly disperse the raw material particles in the system to prevent particle aggregation or sedimentation.

[0047] It should be noted that an excessive amount of the benzidine-modified polyurethane prepolymer will lead to excessive crystallization, which in turn will cause problems such as embrittlement of the polyurethane material and difficulty in processing. An insufficient amount of the benzidine-modified polyurethane prepolymer will result in insufficient crystallization, leading to weak cohesive force and weakening of mechanical properties and adhesion. The technical solution of the present invention comprehensively considers the balance among crystallinity, hydrogen bond strength, processing performance, and safety, and sets the amount of the benzidine-modified polyurethane prepolymer within the above range. An excessive amount of the aromatic isocyanate-modified epoxy resin prepolymer will lead to a too high proportion of hard segments, resulting in a decrease in the flexibility of the prepared polyurethane material, an imbalance in crosslinking density, and too high a glass transition temperature. An insufficient amount of the aromatic isocyanate-modified epoxy resin prepolymer will lead to a weakening of the intermolecular force, resulting in a decrease in heat resistance and chemical resistance. The technical solution of the present invention comprehensively considers the balance among flexibility, crosslinking density, heat resistance, and chemical resistance, and sets the amount of the aromatic isocyanate-modified epoxy resin prepolymer within the above range.

[0048] In the embodiment of the present invention, the molecular weight of the benzidine-modified polyurethane prepolymer is 1000 - 3000. The benzidine-modified polyurethane prepolymer with a higher molecular weight can form a denser network structure after curing, making the product have higher tensile strength and tear strength. However, due to its larger size and more complex structure, the prepolymer with a larger molecular weight affects the reaction activity, and the higher molecular weight will result in longer and more entangled polymer chains, which will limit the ordered arrangement of chain segments, thereby reducing the crystallinity. Comprehensively considering the balance among crystallinity, mechanical properties, and reaction activity, the technical solution of the present invention controls the molecular weight of the benzidine-modified polyurethane prepolymer within the range of 1000 - 3000.

[0049] In the embodiment of the present invention, the molecular weight of the aromatic isocyanate-modified epoxy resin prepolymer is 800 - 2000. The benzidine-modified polyurethane prepolymer with a higher molecular weight can form a denser network structure after curing, making the product have higher tensile strength and tear strength. The prepolymer with a higher molecular weight forms longer and more flexible chain segments after curing, having higher flexibility and a lower Tg value; the prepolymer with a lower molecular weight has higher reaction activity, and the shorter chain segments can expose more active end groups, making it easier to crosslink with other components, thereby achieving a high crosslinking density. Comprehensively considering the balance among flexibility, crosslinking density, mechanical properties, and reaction activity, the molecular weight of the aromatic isocyanate-modified epoxy resin prepolymer is controlled within the range of 800 - 2000.

[0050] In an embodiment of the present invention, in the step of preparing the aromatic isocyanate-modified epoxy resin prepolymer, the aromatic isocyanate includes at least one of toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and naphthalene 1,5-diisocyanate (NDI). In an embodiment of the present invention, toluene diisocyanate (TDI) is used to prepare the aromatic isocyanate-modified epoxy resin prepolymer.

[0051] In an embodiment of the present invention, the initiator of the polyether polyol is glycerol. The glycerol molecule contains three hydroxyl groups (functionality of 3). As an initiator, it can guide the polyether polyol to form a branched structure. Moreover, the polyether polyol prepared with glycerol as the initiator has a higher hydroxyl value and stronger activity when reacting with isocyanate, which can shorten the curing time or reduce the catalyst dosage, thereby improving production efficiency. Selecting such a high-functionality initiator is also beneficial for significantly increasing the crosslinking density in the subsequent polyurethane synthesis, endowing the material with higher mechanical strength and dimensional stability. At the same time, the higher crosslinking degree restricts the thermal movement of molecular chains, which is conducive to enhancing the heat resistance of the polyurethane and making it less likely to soften or deform in a high-temperature environment.

[0052] In an embodiment of the present invention, the average functionality of the polyether polyol is 3, and the average molecular weight is 300 - 2000. Low-molecular-weight polyether polyols (such as 300 - 2000) contain more terminal hydroxyl groups (per unit mass). When reacting with isocyanate, they can form a higher crosslinking density, thereby enhancing the strength, hardness, and chemical resistance of the adhesive. Moreover, the reaction rate of low-molecular-weight polyols is fast, which helps to shorten the curing time and improve the initial adhesion, meeting the industrial requirements for rapid curing. When the molecular weight is too high (>2000), the hydroxyl concentration decreases, resulting in insufficient crosslinking and affecting the cohesion. In addition, low-molecular-weight polyols have a lower viscosity, which is easy to mix and process, reducing the dependence on solvents or plasticizers, improving production efficiency and environmental friendliness. The high viscosity of high-molecular-weight polyols may cause processing difficulties. Furthermore, polyols with a molecular weight in the range of 300 - 2000 can achieve a balance between hardness and flexibility. If the molecular weight is too low (such as <300), the adhesive may be too brittle; if it is too high (such as >2000), the material will be too soft, and the strength and modulus will decrease. The technical solution of the present invention uses a polyether polyol with an average molecular weight of 300 - 2000. Polyols in this molecular weight range have better compatibility with other components (such as isocyanate and additives), which is beneficial for reducing the risk of phase separation and ensuring the uniformity and stability of the adhesive.

[0053] In an embodiment of the present invention, the initiator of the polyester polyol is phthalic acid. Selecting phthalic acid as the initiator is beneficial to significantly increasing the crosslinking density in the subsequent polyurethane synthesis, endowing the material with higher mechanical strength and dimensional stability. Moreover, the higher crosslinking degree restricts the thermal movement of molecular chains, which is conducive to improving the heat resistance of the polyurethane, making it less likely to soften or deform in a high-temperature environment. Additionally, the rigid benzene ring in the molecular structure of terephthalic acid helps to form a more compact and ordered arrangement of polymer chains, which is beneficial to enhancing the mechanical properties.

[0054] In an embodiment of the present invention, the average functionality of the polyester polyol is 2, and the average molecular weight is 2000 - 5000. Low-molecular-weight polyols have lower viscosities, are easy to mix and process, can reduce the dependence on solvents or plasticizers, and improve production efficiency and environmental friendliness; the high viscosities of high-molecular-weight polyols may lead to processing difficulties. In addition, polyols with a molecular weight of 2000 - 5000 can achieve a balance between hardness and flexibility. The technical solution of the present invention prepares a polyester polyol using phthalic acid as the initiator and controls the average molecular weight of the polyester polyol to be 2000 - 5000, which is beneficial to preparing a polyurethane with greater strength and adhesion within the molecular chain, thereby exhibiting better properties such as strength and abrasion resistance.

[0055] In an embodiment of the present invention, the isocyanate includes hexamethylene diisocyanate (HDI) or isophorone diisocyanate (IPDI).

[0056] In an embodiment of the present invention, the catalyst includes an organotin catalyst, and the organotin catalyst includes organotin T12 (dibutyltin dilaurate) or organotin catalyst T9 (stannous octoate). The organotin catalyst has an efficient catalytic effect on the reaction between the isocyanate and the polyol. Using the organotin catalyst can significantly accelerate the formation rate of the urethane bond.

[0057] In an embodiment of the present invention, the antioxidant includes BASF 616. The antioxidant is used to inhibit the oxidation of methylene in the thermal oxidation process and delay the yellowing process.

[0058] In an embodiment of the present invention, the ultraviolet absorber includes TinuvinB75. The ultraviolet absorber is used to absorb or transfer ultraviolet energy and reduce the photodegradation reaction. The combined use of the ultraviolet absorber and the antioxidant can synergistically improve the yellowing resistance effect.

[0059] In an embodiment of the present invention, the defoamer includes Dow Corning 3168.

[0060] In an embodiment of the present invention, the wetting agent includes Dow Corning DC67.

[0061] In an embodiment of the present invention, the dispersant includes Corning DC3.

[0062] In an embodiment of the present invention, the benzidine-modified polyurethane prepolymer is prepared by the following steps:

[0063] Mix polyether polyol and diisocyanate and carry out a first addition reaction to obtain a prepolymer;

[0064] Mix benzidine and an organic solvent to obtain a benzidine solution, and then mix the benzidine solution and the prepolymer to carry out a second addition reaction to obtain a benzidine-modified polyurethane prepolymer.

[0065] In an embodiment of the present invention, in the step of mixing polyether polyol and diisocyanate and carrying out a first addition reaction to obtain a prepolymer, the temperature of the first addition reaction is 70-90 °C, and the time of the first addition reaction is 2-4 h. Exemplarily, the temperature of the first addition reaction can be 70 °C, 80 °C or 90 °C, and the time of the first addition reaction can be 2 h, 3 h or 4 h.

[0066] In an embodiment of the present invention, in the step of mixing benzidine and an organic solvent to obtain a benzidine solution, and then mixing the benzidine solution and the prepolymer to carry out a second addition reaction to obtain a benzidine-modified polyurethane prepolymer, the temperature of the second addition reaction is 50-70 °C, and the time of the addition reaction is 1-3 h. Exemplarily, the temperature of the second addition reaction can be 50 °C, 60 °C or 70 °C, and the time of the second addition reaction can be 1 h, 2 h or 3 h.

[0067] In the process of preparing benzidine-modified polyurethane prepolymer, first, polyether polyol is dehydrated under vacuum at 100 - 120 °C (vacuum degree ≤ 0.1 MPa) for 1 - 2 h to make the water content < 0.05%; subsequently, the dehydrated polyether polyol and diisocyanate are mixed and heated at 70 - 90 °C for 2 - 4 h to allow the addition reaction between isocyanate groups (-NCO) and hydroxyl groups (-OH) to generate urethane bonds (-NHCOO-). After the reaction ends, the prepolymer is obtained. Among them, reacting at 70 - 90 °C for 2 - 4 h is beneficial to controlling the reaction rate and molecular weight and avoiding excessive cross-linking or gelation. During the reaction process, the content of free -NCO groups in the prepolymer is determined by the dibutylamine titration method, and the reaction can be stopped when the theoretical value is reached; subsequently, the benzidine solution and the prepolymer are mixed and heated at 50 - 70 °C for 1 - 3 h to allow the amino groups (-NH2) in benzidine to react with the remaining isocyanate groups (-NCO) in the prepolymer to generate urea bonds (-NH-CO-NH-). After the reaction ends, the solvent is removed by vacuum distillation or rotary evaporation and then vacuum dried to obtain the benzidine-modified polyurethane prepolymer. Among them, reacting at 50 - 70 °C helps to prevent local overheating, control the reaction rate, and ensure sufficient reaction because too high a temperature may lead to an increase in side reactions or unnecessary cross-linking of the prepolymer, while too low a temperature may cause incomplete reaction and affect the performance of the final product. During the reaction process, the change in the viscosity of the system is monitored to prevent gelation.

[0068] In an embodiment of the present invention, the addition amounts of the polyether polyol and the diisocyanate are calculated according to the molar ratio of the hydroxyl groups in the polyether polyol to the isocyanate groups in the diisocyanate being 1:

[0069] (2 - 3). Setting the addition amounts of the polyether polyol and the diisocyanate within the above range enables most of the isocyanate groups (-NCO) on the diisocyanate to first undergo an addition reaction with the hydroxyl groups (-OH) fully and be converted into urethane bonds (-NHCOO-), and the remaining isocyanate groups (-NCO) on the diisocyanate will be used for the subsequent reaction with benzidine. In an embodiment of the present invention, the molar ratio of the hydroxyl groups in the polyether polyol to the isocyanate groups in the diisocyanate is set to 1:2.

[0070] In an embodiment of the present invention, the addition amounts of the benzidine and the prepolymer are calculated according to the molar ratio of the amino groups of the benzidine to the isocyanate groups of the prepolymer being (2 - 3):1. Setting the mass ratio of the benzidine and the prepolymer within the above range helps for sufficient reaction and controls the molecular weight within 1000 - 3000.

[0071] In an embodiment of the present invention, the aromatic isocyanate-modified epoxy resin prepolymer is prepared by the following steps:

[0072] Epoxy resin, aromatic isocyanate and a catalyst are mixed to carry out a third addition reaction to obtain an aromatic isocyanate-modified epoxy resin prepolymer.

[0073] In the examples of the present invention, in the step of mixing epoxy resin, aromatic isocyanate and a catalyst to carry out a third addition reaction to obtain an aromatic isocyanate-modified epoxy resin prepolymer, the temperature of the third addition reaction is 70-90 °C, and the time of the third addition reaction is 2-4 h. Exemplarily, the temperature of the third addition reaction can be 70 °C, 80 °C or 90 °C, and the time of the third addition reaction can be 2 h, 3 h or 4 h.

[0074] In the process of preparing the aromatic isocyanate-modified epoxy resin prepolymer, first, the epoxy resin is vacuum dried at 80-100 °C for 2-4 h to make the water content <0.05%; subsequently, the dehydrated epoxy resin, aromatic isocyanate and a catalyst are mixed and heated at 70-90 °C for 2-4 h to carry out an addition reaction between isocyanate groups (-NCO) and hydroxyl groups (-OH) to form urethane bonds (-NHCOO-), and the content of free -NCO groups in the prepolymer is determined by the dibutylamine titration method until the theoretical value is reached. When the -NCO content reaches the target value, the temperature is lowered to room temperature, and the product is stored sealed and away from light.

[0075] In the examples of the present invention, in the step of mixing epoxy resin, aromatic isocyanate and a catalyst to carry out a third addition reaction to obtain an aromatic isocyanate-modified epoxy resin prepolymer:

[0076] The addition amounts of the epoxy resin and the aromatic isocyanate are calculated according to the molar ratio of the hydroxyl groups in the epoxy resin to the isocyanate groups in the aromatic isocyanate being 1:(1-1.2). An excessive amount of aromatic isocyanate is used to make the epoxy resin react fully. In an embodiment of the present invention, the molar ratio of the hydroxyl groups in the epoxy resin to the isocyanate groups in the aromatic isocyanate is set to 1:1.2.

[0077] In the examples of the present invention, in the step of preparing the aromatic isocyanate-modified epoxy resin prepolymer, the catalyst includes dibutyltin dilaurate (DBTDL), and the catalyst dosage is 0.1%-0.5% of the total mass of the epoxy resin and the aromatic isocyanate. Since the reaction between epoxy resin and aromatic isocyanate is usually slow, adding a catalyst is beneficial to improving the reaction rate and ensuring complete reaction. Organotin catalysts (such as dibutyltin dilaurate) have a high catalytic effect on the reaction of isocyanate with polyol and can significantly accelerate the reaction rate.

[0078] The present invention also provides a method for preparing the two-component polyurethane potting adhesive for crystal film screen encapsulation, which includes the preparation of component A and the preparation of component B;

[0079] The preparation of component A includes: mixing polyether polyol and polyester polyol to obtain a first mixture, and dehydrating the first mixture to obtain component A;

[0080] The preparation of component B includes: mixing an antioxidant, a benzidine-modified polyurethane prepolymer and an aromatic isocyanate-modified epoxy resin prepolymer to obtain a second mixture, dehydrating the second mixture, and then mixing the dehydrated second mixture with a catalyst, an ultraviolet absorber, an antifoaming agent, a wetting agent and a dispersant to obtain component B.

[0081] In an embodiment of the present invention, the preparation of component A specifically includes:

[0082] Mixing polyether polyol and polyester polyol to obtain a first mixture, and vacuum dehydrating the first mixture at 100-130 °C until the water content is less than 500 ppm to obtain component A.

[0083] When preparing the two-component polyurethane potting adhesive for crystal film screen encapsulation, dehydrate the polyether polyol and polyester polyol with relatively high water content to reduce the influence of water on the isocyanate reaction.

[0084] In an embodiment of the present invention, the preparation of component B specifically includes:

[0085] The preparation of component B includes: mixing an antioxidant, a benzidine-modified polyurethane prepolymer and an aromatic isocyanate-modified epoxy resin prepolymer to obtain a second mixture, vacuum drying the second mixture at 80-100 °C for 2-4 h until the water content is less than 500 ppm, and then mixing the dehydrated second mixture with a catalyst, an ultraviolet absorber, an antifoaming agent, a wetting agent and a dispersant to obtain component B.

[0086] The present invention provides an application of the two-component polyurethane potting adhesive for crystal film screen encapsulation in crystal film screen encapsulation.

[0087] In an embodiment of the present invention, the application of the two-component polyurethane potting adhesive for crystal film screen encapsulation in crystal film screen encapsulation includes the following steps:

[0088] Provide a crystal film screen, mix component A and component B according to a mass ratio of 100:(50-100) to obtain the two-component polyurethane potting adhesive for crystal film screen encapsulation, fill the two-component polyurethane potting adhesive for crystal film screen encapsulation at the bonding position to be bonded of the crystal film screen, and cure it.

[0089] If the proportion of component B is too high, it will cause a decrease in the flexibility of the material, an imbalance in the crosslinking density, and an excessively high glass transition temperature; if the proportion of component B is too low, it will lead to a weakening of the intermolecular force, resulting in a decrease in heat resistance and chemical resistance. In the technical solution of the present invention, component A and component B are mixed in a mass ratio of 100:(50-100), and the obtained two-component polyurethane potting adhesive has good comprehensive performance.

[0090] In an embodiment of the present invention, component A and component B can be used after being mixed at 15-40°C for 3-5 minutes. At this time, component A and component B can form a dense crosslinking system, and the strength of the two-component polyurethane potting adhesive product for crystal film screen encapsulation is better.

[0091] In an embodiment of the present invention, after component A and component B are mixed, they are filled at the bonding position of the crystal film screen within 2-6 hours. It is convenient for construction to control the use within 2-6 hours. Exceeding 6 hours may cause the hardness after curing to be too high and difficult to construct.

[0092] In an embodiment of the present invention, the curing temperature is 20-30°C, and the curing time is 3-5 hours. The two-component polyurethane encapsulating adhesive provided by the technical solution of the present invention can be cured at room temperature, which is convenient for construction and operation. In an embodiment of the present invention, the curing temperature is set at 25°C, and the curing time is 4 hours.

[0093] The technical solution of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0094] In the following embodiments, the polyester polyol is purchased from Yangzi BASF HYP20; the polyether polyol is purchased from Wanhua Chemical C2010; the antioxidant is purchased from BASF 616; the catalyst is the organotin catalyst T12 (dibutyltin dilaurate); the ultraviolet absorber is purchased from BASF TinuvinB75 sold in the market; the defoaming agent is purchased from Dow Corning 3168; the wetting agent is purchased from Dow Corning DC67; the dispersant is purchased from Dow Corning DC3.

[0095] Example 1

[0096] A preparation method of a benzidine-modified polyurethane prepolymer includes the following steps:

[0097] (1) Add polyether polyol (molecular weight of 1000, functionality of 3) to a reaction flask, dehydrate it under vacuum (vacuum degree ≤ 0.1 MPa) at 100°C for 1-2 hours until the water content < 0.05%. Cool down to 60, and protect it with nitrogen.

[0098] (2) Mix the dehydrated polyether polyol and diisocyanate, and conduct the first addition reaction at 80 °C for 3 h to obtain a prepolymer; wherein, the addition amounts of the polyether polyol and diisocyanate are calculated according to the molar ratio of the hydroxyl groups in the polyether polyol to the isocyanate groups in the diisocyanate being 1:2;

[0099] (3) Dissolve 200 g of benzidine in 50 mL of anhydrous DMF, and stir until completely dissolved. Then, dropwise add the benzidine solution to 1 kg of the prepolymer, control the temperature at 60 °C, and continue stirring for the second addition reaction for 3 hours. After the reaction ends, cool down to room temperature to stop the reaction, remove the solvent by vacuum distillation, and conduct vacuum drying to obtain a benzidine-modified polyurethane prepolymer (isocyanate content is 8%).

[0100] Example 2

[0101] A preparation method of an aromatic isocyanate-modified epoxy resin prepolymer includes the following steps:

[0102] (1) Vacuum-dry the epoxy resin (epoxy value is 0.40 eq / 100 g) at 100 °C for 4 h, add the dehydrated epoxy resin to a dry three-necked flask, and protect it with nitrogen.

[0103] (2) Mix the epoxy resin, toluene diisocyanate, and dibutyltin dilaurate catalyst, conduct the third addition reaction at 80 °C for 4 h, and cool down to room temperature to obtain an aromatic isocyanate-modified epoxy resin prepolymer, which is sealed and stored away from light; wherein, the addition amounts of the epoxy resin and toluene diisocyanate are calculated according to the molar ratio of the hydroxyl groups in the epoxy resin to the isocyanate groups in the toluene diisocyanate being 1:1.2; the dosage of the catalyst is 0.2% of the total mass of the epoxy resin and aromatic isocyanate.

[0104] Example 3

[0105] A two-component polyurethane potting adhesive for crystal film screen encapsulation includes component A and component B; wherein:

[0106] Component A includes polyether polyol and polyester polyol;

[0107] Component B includes benzidine-modified polyurethane prepolymer, aromatic isocyanate-modified epoxy resin prepolymer, catalyst, antioxidant, ultraviolet absorber, defoamer, wetting agent, and dispersant;

[0108] The preparation method of the two-component polyurethane potting adhesive for crystal film screen encapsulation includes the following steps:

[0109] (1) Mix 600 g of polyether polyol (molecular weight of 1000 and functionality of 3) and 400 g of polyester polyol (molecular weight of 3000 and functionality of 2) to obtain a first mixture. Vacuum dehydrate the mixture at 120 °C until the moisture content is lower than 500 ppm. Wait for the temperature to drop to 50 °C to prepare Component A, which is filled with nitrogen and stored in a barrel for later use;

[0110] (2) Mix 40 g of antioxidant, 300 g of benzidine-modified polyurethane prepolymer of Example 1, and 500 g of aromatic isocyanate-modified epoxy resin prepolymer of Example 2 to obtain a second mixture. Vacuum dry the second mixture at 100 °C and dehydrate until the moisture content is lower than 500 ppm. After the temperature drops to 45 °C, add 50 g of catalyst, 20 g of ultraviolet absorber, 10 g of defoamer, 5 g of wetting agent, and 10 g of dispersant to prepare Component B, which is filled with nitrogen and stored in a barrel for later use;

[0111] (3) Mix Component A and Component B prepared in steps (1) and (2) evenly according to a mass ratio of 100:60 to obtain a two-component polyurethane potting adhesive for crystal film screen encapsulation.

[0112] Example 4

[0113] Compared with Example 3, the difference is that 500 g of polyether polyol and 500 g of polyester polyol are used when preparing Component A; 50 g of antioxidant, 400 g of benzidine-modified polyurethane prepolymer, 400 g of aromatic isocyanate-modified epoxy resin prepolymer, 40 g of catalyst, 20 g of ultraviolet absorber, 10 g of defoamer, 10 g of wetting agent, and 10 g of dispersant are used when preparing Component B.

[0114] Example 5

[0115] Compared with Example 3, the difference is that 300 g of polyether polyol and 700 g of polyester polyol are used when preparing Component A; 30 g of antioxidant, 500 g of benzidine-modified polyurethane prepolymer, 400 g of aromatic isocyanate-modified epoxy resin prepolymer, 50 g of catalyst, 15 g of ultraviolet absorber, 10 g of defoamer, 5 g of wetting agent, and 10 g of dispersant are used when preparing Component B.

[0116] Example 6

[0117] Compared with Example 3, the difference is that the mass ratio of Component A to Component B is 100:50.

[0118] Example 7

[0119] Compared with Example 3, the difference is that the mass ratio of Component A to Component B is 100:100.

[0120] Example 8

[0121] Compared with Example 3, the difference lies in that the molecular weight of the polyester polyol is 2000.

[0122] Example 9

[0123] Compared with Example 3, the difference lies in that the molecular weight of the polyester polyol is 5000.

[0124] Example 10

[0125] Compared with Example 3, the difference lies in that the molecular weight of the polyether polyol is 300.

[0126] Example 11

[0127] Compared with Example 3, the difference lies in that the molecular weight of the polyether polyol is 2000.

[0128] Comparative Example 1

[0129] Compared with Example 3, the difference lies in that the benzidine-modified polyurethane prepolymer is not contained, and isophorone diisocyanate is used to replace the benzidine-modified polyurethane prepolymer.

[0130] Comparative Example 2

[0131] Compared with Example 3, the difference lies in that the aromatic isocyanate-modified epoxy resin prepolymer is not contained in Component A, and isophorone diisocyanate is used to replace the aromatic isocyanate-modified epoxy resin prepolymer.

[0132] Comparative Example 3

[0133] Compared with Example 3, the difference lies in that the mass ratio of Component A to Component B is 100:150.

[0134] Comparative Example 4

[0135] Compared with Example 3, the difference lies in that the mass ratio of Component A to Component B is 100:30.

[0136] Performance Test

[0137] Use the two-component polyurethane potting adhesive for crystal film screen encapsulation and the commercially available epoxy potting adhesive of Examples 3-11 and Comparative Examples 1-4 to encapsulate the crystal film screen, and test the light transmittance, hardness, high temperature and high humidity resistance performance, appearance, substrate adhesion, yellowing resistance performance and high and low temperature shrinkage rate. The test results are shown in Table 1.

[0138] The encapsulation method of the two-component polyurethane potting adhesive for crystal film screen encapsulation of Examples 3-11 and Comparative Examples 1-4 is as follows:

[0139] (1) Pour the A and B components of Examples 3 - 11 and Comparative Examples 1 - 4 into the glue buckets of the encapsulation equipment respectively. Tighten the lids of the glue buckets and remove the air bubbles in the glue under vacuum. Adjust the dispensing ratio of the A and B components, and mix the A and B components evenly according to the preset mass ratios in Examples 3 - 11 and Comparative Examples 1 - 4 to obtain polyurethane potting compounds.

[0140] (2) Fix the crystal film screen flatly on the glass substrate, and transport the glass substrate together with the crystal film screen into the vacuum chamber of the encapsulation equipment. Fill the two - component polyurethane potting adhesive for crystal film screen encapsulation in step (1), and perform vacuum degassing and leveling after filling.

[0141] The encapsulation method of commercially available epoxy potting adhesive is as follows:

[0142] Fix the crystal film screen flatly on the glass substrate, and transport the glass substrate together with the crystal film screen into the vacuum chamber of the encapsulation equipment. Fill the commercially available epoxy potting adhesive (Huitian 6302 epoxy resin potting adhesive), and perform vacuum degassing and leveling after filling.

[0143] Light transmittance test method: Conduct according to the method of GB / T 2410 - 2008.

[0144] Hardness test method: Conduct according to the method of GB / T 2411 - 2008.

[0145] High - temperature and high - humidity performance test method: Conduct tests according to the methods of GB / T 2423 - 2008 and GB / T 4708 - 2008. Place the crystal film screen in a high - temperature and high - humidity test chamber for double 85 tests.

[0146] Test method for substrate adhesion: Conduct according to ASTM D3359.

[0147] Yellowing resistance performance: Conduct tests according to GB / T 39822 - 2021. Place the crystal film screen under ultraviolet irradiation at a wavelength of 340 nm for testing.

[0148] High - and low - temperature shrinkage rate test method: Conduct according to the method of GB / T 39818 - 2021.

[0149] Table 1 Performance test results of two - component polyurethane potting adhesives for crystal film screen encapsulation in Examples 3 - 11 and Comparative Examples 1 - 4 and commercially available epoxy potting adhesive

[0150]

[0151]

[0152] As can be seen from Table 1, compared with the commercially available epoxy potting adhesives, the light transmittance of the two-component polyurethane potting adhesives provided in Examples 3-11 of the present invention is better than that of the commercially available epoxy potting adhesives. The results of the double 85 test, substrate adhesion, yellowing resistance test, and high and low temperature shrinkage rate test are also better than those of the commercially available epoxy potting adhesives, indicating that the two-component polyurethane potting adhesives provided by the present invention are beneficial to improving light transmittance, substrate adhesion, and yellowing resistance, and have a small high and low temperature shrinkage rate, with a flat and beautiful appearance.

[0153] As can be seen from the test results of Example 3, Example 6, and Example 7, as the proportion of Component B increases, the hardness of the two-component polyurethane potting adhesive first increases and then decreases, the substrate adhesion shows an increasing trend, and the high and low temperature shrinkage rate first becomes smaller and then larger.

[0154] As can be seen from Example 3, Example 8, and Example 9, the molecular weight of the polyether polyol will affect the hardness, high temperature and high humidity resistance, substrate adhesion, high and low temperature resistance, and high and low temperature shrinkage rate of the two-component polyurethane potting adhesive. As the molecular weight increases, the hardness first increases and then decreases, the high temperature and high humidity resistance first improves and then shows a downward trend, the substrate adhesion shows an increasing trend, the yellowing resistance shows a deteriorating trend, and the high and low temperature shrinkage rate first becomes smaller and then larger.

[0155] As can be seen from Example 3, Example 10, and Example 11, the molecular weight of the polyol polyol will affect the hardness, high temperature and high humidity resistance, substrate adhesion, high and low temperature resistance, and high and low temperature shrinkage rate of the two-component polyurethane potting adhesive. As the molecular weight increases, the hardness first increases and then decreases, the high temperature and high humidity resistance first improves and then shows a downward trend, the substrate adhesion shows an increasing trend, the yellowing resistance shows a deteriorating trend, and the high and low temperature shrinkage rate first becomes smaller and then larger.

[0156] As can be seen from Example 3 and Comparative Examples 1-2, without the benzidine-modified polyurethane prepolymer or without the aromatic isocyanate-modified epoxy resin prepolymer, the test results of the light transmittance, hardness, high temperature and high humidity resistance, substrate adhesion, yellowing resistance, and high and low temperature shrinkage rate of the two-component polyurethane potting adhesive all deteriorate.

[0157] As can be seen from Example 3, Example 8-9, and Comparative Examples 3-4, when the mass ratio of Component A to Component B exceeds 100:(50-100), the test results of the light transmittance, high temperature and high humidity resistance, substrate adhesion, yellowing resistance, and high and low temperature shrinkage rate of the two-component polyurethane potting adhesive deteriorate.

[0158] The above description is only an exemplary embodiment of the present invention and does not limit the scope of the present invention. Any equivalent structural transformation made using the content of the specification of the present invention under the technical concept of the present invention, or any direct / indirect application in other related technical fields, is included in the protection scope of the present invention.

Claims

1. A two-component polyurethane potting adhesive for encapsulating a crystal film screen, characterized in that, The two-component polyurethane potting glue for crystal film screen packaging includes component A and component B; wherein: The component A comprises, by weight: 30 to 60 parts of polyether polyol and 40 to 70 parts of polyester polyol; The B component includes, by mass, 30 to 50 parts of benzidine-modified polyurethane prepolymer, 40 to 50 parts of aromatic isocyanate-modified epoxy resin prepolymer, 4 to 5 parts of catalyst, 3 to 5 parts of antioxidant, 1 to 2 parts of ultraviolet absorber, 1 to 2 parts of defoamer, 0.5 to 1 part of wetting agent and 0.5 to 1 part of dispersant.

2. The two-component polyurethane potting adhesive for crystal film screen encapsulation according to claim 1, wherein The molecular weight of the benzidine-modified polyurethane prepolymer is 1000 to 3000; and / or, The molecular weight of the aromatic isocyanate-modified epoxy resin prepolymer is 800 to 2000; and / or, The aromatic isocyanate in the aromatic isocyanate-modified epoxy resin prepolymer includes at least one of toluene diisocyanate, diphenylmethane diisocyanate and naphthalene 1,5-diisocyanate; and / or, The initiator of the polyether polyol is glycerol; and / or, The polyether polyol has an average functionality of 3 and an average molecular weight of 300 to 2000; and / or, The initiator of the polyester polyol is phthalic acid; and / or, The polyester polyol has an average functionality of 2 and an average molecular weight of 2000 to 5000; and / or, The isocyanate comprises hexamethylene diisocyanate or isophorone diisocyanate; and / or, The catalyst includes an organotin catalyst, and the organotin catalyst includes organotin catalyst T12 or organotin catalyst T9.

3. The two-component polyurethane potting adhesive for encapsulating a crystal film screen according to claim 1, wherein, The benzidine modified polyurethane prepolymer is prepared by the following steps: The polyether polyol and the diisocyanate are mixed and subjected to a first addition reaction to obtain a prepolymer; Benzidine and an organic solvent are mixed to obtain a benzidine solution, and then the benzidine solution and the prepolymer are mixed to perform a second addition reaction to obtain a benzidine-modified polyurethane prepolymer.

4. The two-component polyurethane potting adhesive for encapsulating a crystal film screen according to claim 3, wherein, The addition amounts of the polyether polyol and the diisocyanate are calculated based on a molar ratio of the hydroxyl group of the polyether polyol to the isocyanate group of the diisocyanate of 1:(2-3); and / or, The added amounts of the benzidine and the prepolymer are calculated based on a molar ratio of the amino group of the benzidine to the isocyanate group of the prepolymer of (2-3):

1.

5. The two-component polyurethane potting adhesive for encapsulating a crystal film screen according to claim 1, wherein, The aromatic isocyanate-modified epoxy resin prepolymer is prepared by the following steps: The epoxy resin, aromatic isocyanate and a catalyst are mixed and subjected to a third addition reaction to obtain an aromatic isocyanate-modified epoxy resin prepolymer.

6. The two-component polyurethane potting adhesive for encapsulating a crystal film screen according to claim 5, wherein, In the step of mixing the epoxy resin, the aromatic isocyanate and the catalyst, and performing a third addition reaction to obtain the aromatic isocyanate-modified epoxy resin prepolymer: The added amounts of the epoxy resin and the aromatic isocyanate are calculated based on a molar ratio of hydroxyl groups in the epoxy resin to isocyanate groups in the aromatic isocyanate of 1:(1-1.2).

7. A preparation method of a two-component polyurethane potting adhesive for encapsulating a crystal film screen according to any one of claims 1 to 6, characterized in that, The preparation method includes the preparation of component A and the preparation of component B; The preparation of the component A includes: mixing polyether polyol and polyester polyol to obtain a first mixture, and dehydrating the first mixture to obtain the component A; The preparation of the component B includes: mixing an antioxidant, a benzidine-modified polyurethane prepolymer and an aromatic isocyanate-modified epoxy resin prepolymer to obtain a second mixture, dehydrating the second mixture, and then mixing the dehydrated second mixture with a catalyst, an ultraviolet absorber, an antifoaming agent, a wetting agent and a dispersing agent to obtain the component B.

8. Use of a two-component polyurethane potting adhesive for encapsulating a crystal film screen according to any one of claims 1 to 6 in encapsulating a crystal film screen.

9. Use of the two-component polyurethane potting adhesive for encapsulating crystal film screens according to claim 8 in encapsulating crystal film screens, characterized in that, It includes the following steps: Providing a crystal film screen, mixing the component A and the component B in a mass ratio of 100:(50-100) to obtain a two-component polyurethane potting adhesive for encapsulating a crystal film screen, and filling the two-component polyurethane potting adhesive for encapsulating a crystal film screen at the bonding position to be bonded of the crystal film screen for curing.

10. The application of the two-component polyurethane potting adhesive for crystal film screen encapsulation according to claim 9 in crystal film screen encapsulation, characterized in that, Mixing the component A and the component B at 15-40 °C for 3-5 min; and / or, After mixing the component A and the component B, filling at the bonding position to be bonded of the crystal film screen within 2-6 h; and / or, The curing parameters are: the curing temperature is 20-30 °C, and the curing time is 3-5 h.

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