Bi-component polyurethane pouring sealant as well as preparation method and application thereof

Abstract

The invention discloses a two-component polyurethane pouring sealant as well as a preparation method and application thereof, and relates to the technical field of adhesives. The bi-component polyurethane pouring sealant comprises a component A and a component B, wherein the component A is prepared from 10 to 90 parts of acryloyloxy-terminated polyether polyol, 10 to 60 parts of polyester polyol, 10 to 20 parts of hydroxyl-terminated polybutadiene prepolymer and 1 to 2 parts of an initiator; and the component B comprises 30-70 parts of isocyanate and 5-20 parts of a catalyst. According to the technical scheme, the acrylic acid chain segment is added into the polyether polyol, so that the mechanical strength is favorably improved, and meanwhile, the light transmittance is also improved; by adding the polyolefin prepolymer, the air tightness is further enhanced, and meanwhile, the yellowing resistance is also improved. The bi-component polyurethane pouring sealant disclosed by the invention has good light transmission, high-temperature and high-humidity resistance, yellowing resistance and high-temperature and high-humidity resistance, and can be used for packaging MINI LED screens.

Description

Technical Field

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

[0002] MINI LED screen is a new display technology with the advantages of good consistency and high brightness. Its display effect is comparable to that of an organic electroluminescent display screen (OLED screen), and it is not easy to burn the screen and has a long service life. At present, MINI LED screens are developing towards large screens, but large-screen MINI LED screens face problems such as high packaging difficulty and low yield. In addition to requiring the potting adhesive to have good light transmittance and thermal stability, it is also required to be flat, yellowing-resistant, and have good airtightness.

[0003] The commonly used potting adhesives for MINI LED screens on the market mainly include two types: epoxy resin matrix glue and silicone resin matrix glue. Epoxy resin is the current mainstream potting adhesive for MINI LED screens due to its high hardness, good airtightness, and high reliability. However, since the shrinkage rate of epoxy resin is greater than that of the substrate, epoxy resin matrix glue generally has problems such as easy warping and easy cracking after curing. In addition, epoxy resin matrix glue also has problems such as poor yellowing resistance, poor high-temperature and high-humidity resistance, poor thermal shock resistance, and poor low-temperature resistance; silicone resin has problems such as high viscosity, poor fluidity, low mechanical strength, and weak airtightness.

[0004] Therefore, developing a potting adhesive with good airtightness, yellowing resistance, and high and low temperature resistance is of great significance for meeting the packaging requirements of MINILED screens. Summary of the Invention

[0005] The main object of the present invention is to propose a two-component polyurethane potting adhesive and a preparation method and application thereof, aiming to solve the problems of poor airtightness, poor yellowing resistance, and poor high and low temperature resistance existing in the existing adhesives for MINI LED screen packaging.

[0006] To achieve the above object, the present invention proposes a two-component polyurethane potting adhesive, and the two-component polyurethane potting adhesive includes component A and component B; wherein:

[0007] Component A includes, by mass parts: 10-90 parts of acryloxy-terminated polyether polyol, 10-60 parts of polyester polyol, 10-20 parts of hydroxyl-terminated polybutadiene prepolymer, and 1-2 parts of initiator;

[0008] Component B includes, by mass parts: 30-70 parts of isocyanate and 5-20 parts of catalyst.

[0009] In one embodiment, the initiator of the acryloyloxy-terminated polyether polyol is 1,4-butanediol.

[0010] In one embodiment, the acryloyloxy-terminated polyether polyol has an average functionality of 3 and an average molecular weight of 300 to 2000.

[0011] In one embodiment, the initiator of the polyester polyol is adipic acid.

[0012] In one embodiment, the polyester polyol has an average functionality of 2 and an average molecular weight of 2000 to 5000.

[0013] In one embodiment, the hydroxy-terminated polybutadiene prepolymer has an average functionality of 2 and an average molecular weight of 1000 to 3000.

[0014] In one embodiment, the initiator includes benzoyl peroxide.

[0015] In one embodiment, the isocyanate includes hexamethylene diisocyanate or isophorone diisocyanate.

[0016] In one embodiment, the catalyst includes an organic zinc catalyst, and the organic zinc catalyst includes zinc isooctanoate.

[0017] In one embodiment, the component B further includes 5 to 11 parts of antioxidant, 3 to 9 parts of ultraviolet absorber, 2 to 5 parts of defoamer, 0.5 to 1 part of wetting agent, and 0.5 to 1 part of dispersant.

[0018] In one embodiment, the component A further includes 2 to 4 parts of silane coupling agent, and the silane coupling agent includes vinyltrimethoxysilane.

[0019] The present invention also provides a method for preparing the two-component polyurethane potting adhesive, and the preparation method includes the preparation of component A and the preparation of component B;

[0020] The preparation of component A includes: mixing the acryloyloxy-terminated polyether polyol and the polyester polyol to obtain a mixture, dehydrating the mixture, and then mixing the dehydrated mixture, the hydroxy-terminated polybutadiene prepolymer and the initiator to obtain component A;

[0021] The preparation of component B includes: mixing the isocyanate and the catalyst to obtain component B.

[0022] In one embodiment, the step of mixing the isocyanate and the catalyst to obtain component B includes:

[0023] Dehydrate the antioxidant, and then mix the dehydrated antioxidant, isocyanate, catalyst, ultraviolet absorber, defoamer, wetting agent and dispersant to obtain Component B.

[0024] In one embodiment, the steps of dehydrating the antioxidant and then mixing the dehydrated antioxidant, isocyanate, catalyst, ultraviolet absorber, defoamer, wetting agent and dispersant to obtain Component B include:

[0025] Dehydrate the antioxidant, and then mix the dehydrated antioxidant, isocyanate, catalyst, ultraviolet absorber, defoamer, wetting agent, dispersant and silane coupling agent to obtain Component B.

[0026] The present invention also provides an application of the two-component polyurethane potting adhesive described above in the encapsulation of MINI LED screens.

[0027] In one embodiment, the application of the two-component polyurethane potting adhesive in the encapsulation of MINI LED screens includes the following steps:

[0028] Provide a MINI LED screen, mix Component A and Component B according to a mass ratio of 100:(40 - 80), and then fill the mixture at the bonding site of the MINI LED screen and cure it.

[0029] In one embodiment, mix Component A and Component B at 15 - 40°C for 3 - 5 minutes; and / or,

[0030] After mixing Component A and Component B, fill the mixture at the bonding site of the MINI LED screen within 2 - 6 hours; and / or,

[0031] The curing parameters are: the curing temperature is 20 - 30°C, and the curing time is 3 - 5 hours.

[0032] In the technical solution of the present invention, a two-component polyurethane potting adhesive is prepared using polyester polyol, acryloxy-terminated polyether polyol, hydroxyl-terminated polybutadiene prepolymer, and isocyanate as the main components. Among them, the introduction of acryloxy can improve the regularity of the polyurethane molecular chain, make the molecular chain arrangement more orderly, facilitate the formation of a uniform molecular structure, reduce the scattering of light, and thus improve the light transmittance. In addition, there is good compatibility between acryloxy and the polyurethane chain segment, which can participate in the cross-linking reaction during the curing process to form a dense network structure, avoid phase separation or aggregation phenomena, reduce the scattering of light, and is also conducive to improving the light transmittance; the polybutadiene prepolymer has properties similar to natural rubber, its molecular chain has high flexibility and low surface polarity. Introducing the polybutadiene prepolymer can effectively reduce the penetration and diffusion of gas molecules in the polyurethane material, thereby improving the airtightness. Moreover, the molecular structure of the polybutadiene prepolymer is relatively stable and not prone to chemical reactions, which can reduce the yellowing phenomenon of polyurethane caused by factors such as oxidation and ultraviolet irradiation during use. In addition, due to the polybutadiene prepolymer also having certain hydrophobicity, it can reduce the erosion of water on the polyurethane material and is also beneficial to reducing the yellowing risk caused by water absorption. Therefore, the technical solution of the present invention, by adding acrylic acid chain segments and polybutadiene prepolymer, and controlling the ratio of each component, enables the prepared two-component polyurethane potting adhesive to have good light transmittance, airtightness, yellowing resistance, and high and low temperature resistance, and can meet the encapsulation requirements of MINI LED screens. Detailed implementation manners

[0033] The following will clearly and completely describe the technical solutions in the embodiments of the present invention 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 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 fall within the scope of protection of the present invention.

[0034] 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 positional relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0035] In addition, if the embodiments of the present invention involve descriptions such as "first", "second", etc., these 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", "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 the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, 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.

[0036] The MINI LED screen is a new type of display technology with advantages such as good consistency and high brightness. Its display effect is comparable to that of an organic electrolaser display screen (OLED screen), and it is not prone to screen burning and has a long service life. Currently, the MINI LED screen is developing towards a large-screen direction, but large-screen MINI LED screens face problems such as high packaging difficulty and low yield. In addition to requiring the encapsulation adhesive to have good light transmittance and thermal stability, it is also required to be flat, resistant to yellowing, and have good airtightness.

[0037] The commonly used encapsulation adhesives for MINI LED screens on the market are mainly two types: epoxy resin matrix adhesives and silicone resin matrix adhesives. Epoxy resin, due to its high hardness, good airtightness, and high reliability, is currently the mainstream encapsulation adhesive for MINI LED screens. However, the shrinkage rate of epoxy resin is greater than that of the substrate, resulting in common problems such as easy warping and cracking after curing for epoxy resin matrix adhesives. In addition, epoxy resin matrix adhesives also have problems such as poor yellowing resistance, poor high-temperature and high-humidity resistance, poor thermal shock resistance, and poor low-temperature resistance; silicone resin has problems such as high viscosity, poor fluidity, low mechanical strength, and weak airtightness. Therefore, developing an encapsulation adhesive with good light transmittance, airtightness, and high and low temperature resistance is of great significance for meeting the encapsulation requirements of MINI LED screens.

[0038] 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., as well as materials with smooth surfaces like metal, glass, rubber, plastic, etc. Polyurethane adhesives have excellent flexibility, impact resistance, chemical resistance, and wear resistance.

[0039] Based on the above background, the present invention provides a two-component polyurethane potting adhesive, which comprises component A and component B; wherein:

[0040] Component A includes, by mass parts: 10 - 90 parts of acryloxy-terminated polyether polyol, 10 - 60 parts of polyester polyol, 10 - 20 parts of hydroxyl-terminated polybutadiene prepolymer, and 1 - 2 parts of initiator;

[0041] Component B includes, by mass parts: 30 - 70 parts of isocyanate and 5 - 20 parts of catalyst.

[0042] In the technical solution of the present invention, a two-component polyurethane potting adhesive is prepared using polyester polyol, acryloxy-terminated polyether polyol, hydroxyl-terminated polybutadiene prepolymer, and isocyanate as main raw materials. Among them, the introduction of acryloxy can improve the regularity of the polyurethane molecular chain, make the molecular chain arrangement more orderly, facilitate the formation of a uniform molecular structure, reduce light scattering, and thus improve the light transmittance. In addition, there is good compatibility between acryloxy and the polyurethane segment, and it can participate in the cross-linking reaction during the curing process to form a dense network structure, avoiding phase separation or aggregation phenomena, reducing light scattering, and also being beneficial to improving the light transmittance; the polybutadiene prepolymer has properties similar to natural rubber, its molecular chain has high flexibility and low surface polarity. Introducing the polybutadiene prepolymer can effectively reduce the penetration and diffusion of gas molecules in the polyurethane material, thereby improving the airtightness. Moreover, the molecular structure of the polybutadiene prepolymer is relatively stable and not prone to chemical reactions, which can reduce the yellowing phenomenon of polyurethane caused by factors such as oxidation and ultraviolet irradiation during use. In addition, due to the polybutadiene prepolymer also having a certain degree of hydrophobicity, it can reduce the erosion of water on the polyurethane material, and is also beneficial to reducing the yellowing risk caused by water absorption. Therefore, the technical solution of the present invention, by increasing the acrylic acid segment and polybutadiene prepolymer, and controlling the ratio of each component, enables the prepared two-component polyurethane potting adhesive to have good light transmittance, airtightness, yellowing resistance, and high and low temperature resistance, and can meet the encapsulation requirements of MINI LED screens.

[0043] It should be noted that in component A, setting the dosages of the acryloxy-terminated polyether polyol, polyester polyol, and hydroxyl-terminated polybutadiene prepolymer within the above ranges is beneficial to obtaining a polyurethane potting adhesive with good mechanical strength, flexibility, and low temperature performance. If the dosages of the three components are lower than the above ranges, it may affect the strength of the glue, and if they are higher than the above ranges, it may lead to poor flexibility and low temperature performance. The initiator is used to decompose to generate free radicals, and these free radicals can attack the double bond in acryloxy, thereby initiating the polymerization reaction.

[0044] In an embodiment of the present invention, the initiator of the acryloyloxy-terminated polyether polyol is 1,4-butanediol (HO-(CH2)4-OH). 1,4-Butanediol has good hydroxyl reactivity and can react with isocyanate quickly and uniformly, improving the synthesis efficiency of polyurethane. Moreover, the molecular structure of 1,4-butanediol is symmetric, which can provide uniform reactivity and contribute to the formation of highly crystalline hard segments. This crystallinity can enhance the mechanical strength of polyurethane, making it exhibit higher toughness and tensile resistance when subjected to external forces. The inventors tested the results using ethylene glycol and 1,4-butanediol as initiators, and the results confirmed that the flexibility of the polyether polyol prepared with 1,4-butanediol as the initiator is better than that with ethylene glycol as the initiator.

[0045] The acryloyloxy-terminated polyether polyol is obtained by converting the terminal hydroxyl group of the polyether polyol into acryloyloxy (-O-C(=O)-CH=CH2). In an embodiment of the present invention, the preparation steps of the acryloyloxy-terminated polyether polyol are as follows:

[0046] Mix 1000 g of polyether polyol, 50 g of acrylic anhydride, 5 g of p-toluenesulfonic acid and 2 L of toluene, react at 60 °C for 3 h, then wash off the excess acid and catalyst with saturated sodium bicarbonate solution, and obtain the acryloyloxy-terminated polyether polyol after drying with anhydrous magnesium sulfate by liquid separation. Among them, the polyether polyol is purchased from Dow CP450.

[0047] In an embodiment of the present invention, the average functionality of the acryloyloxy-terminated polyether polyol is 3, and the average molecular weight is 300-2000. By adjusting the amount of 1,4-butanediol, the average molecular weight of the acryloyloxy-terminated polyether polyol is 300-2000, which can achieve a good balance between the hardness and flexibility of polyurethane.

[0048] In an embodiment of the present invention, the initiator of the polyester polyol is adipic acid. Short-chain dibasic acids such as succinic acid may increase the reaction rate, but the product has strong rigidity, insufficient flexibility and low-temperature resistance; long-chain acids have problems of high cost and reduced reactivity; aromatic acids such as terephthalic acid enhance the thermal stability and strength, but increase the brittleness of the material. Considering the above factors comprehensively, the technical solution of the present invention selects adipic acid as the initiator, which has the advantages of good flexibility, good low-temperature resistance, good hydrolysis resistance, mild reaction conditions, low cost, stable supply and environmental friendliness. The polyester polyol is selected from Evonik 7230 or Covestro 1652.

[0049] 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 polyester polyols can increase the internal stress of the system, thereby improving the adhesion performance of the polyurethane. The technical solution of the present invention prepares polyester polyols using adipic acid as the initiator and controls the average molecular weight of the polyester polyol to be 2000 - 5000, which is beneficial to preparing polyurethanes with greater strength and adhesion within the molecular chain, thus exhibiting better properties such as strength and wear resistance. The synthesis of polyester polyols is mainly completed through the esterification reaction of polyols and polyacids (or acid anhydrides) under the action of a catalyst.

[0050] In an embodiment of the present invention, the hydroxyl-terminated polybutadiene prepolymer is purchased, and the average functionality of the hydroxyl-terminated polybutadiene prepolymer is 2, and the average molecular weight is 1000 - 3000. Controlling the molecular weight of the hydroxyl-terminated polybutadiene prepolymer to be 1000 - 3000 has appropriate viscosity and flexibility, which is beneficial to improving the airtightness and yellowing resistance of the prepared two-component polyurethane material.

[0051] In an embodiment of the present invention, the initiator includes benzoyl peroxide (BPO). In the polymerization reaction of acryloxy groups, BPO can decompose to generate free radicals, and these free radicals can attack the double bonds in acryloxy groups, thereby initiating the polymerization reaction.

[0052] In an embodiment of the present invention, the isocyanate includes hexamethylene diisocyanate (HDI) or isophorone diisocyanate (IPDI).

[0053] In an embodiment of the present invention, the catalyst includes an organic zinc catalyst, and the organic zinc catalyst includes zinc isooctanoate. The zinc ions in the organic zinc catalyst may participate in the formation of the polyurethane network structure, enhancing the hydrolysis resistance and ultraviolet aging resistance of the material and not easily causing yellowing.

[0054] In an embodiment of the present invention, the component B further includes 5 - 11 parts of antioxidant, 3 - 9 parts of ultraviolet absorber, 2 - 5 parts of defoaming agent, 0.5 - 1 part of wetting agent, and 0.5 - 1 part of dispersant.

[0055] In an embodiment of the present invention, the antioxidant includes at least one of pentaerythritol tetrapropionate (antioxidant 1010), BASF 1135 (IRGANOX 1135), IRGANOX 5057, and IRGANOX 245. Antioxidants are used to inhibit the oxidation of methylene groups during the thermal oxidation process and delay the yellowing process.

[0056] In an embodiment of the present invention, the ultraviolet absorber includes at least one of Tinuvin 328, Tinuvin 326326, Tinuvin 1130, Tinuvin 531, and Tinuvin 770. The ultraviolet absorber is used to absorb or transfer ultraviolet energy and reduce the photodegradation reaction. The combined use of ultraviolet absorbers and antioxidants can synergistically improve the yellowing resistance effect.

[0057] In an embodiment of the present invention, the defoamer includes at least one of BYK-065, BYK-066N, BYK-018, BYK-011, and BYK-024.

[0058] In an embodiment of the present invention, the wetting agent includes at least one of BYK306, BYK333, BYK077, EFKA-4010, and EFKA-5210.

[0059] In an embodiment of the present invention, the dispersant includes at least one of BYK-110, BYK-163, EFKA-4063, EFKA-4061, and EFKA-4663.

[0060] In an embodiment of the present invention, the component A further includes 2 to 4 parts of a silane coupling agent, and the silane coupling agent includes vinyltrimethoxysilane. After hydrolysis, vinyltrimethoxysilane can generate silanol, react with isocyanate, which is beneficial to form a dense network structure and consume moisture at the same time, thereby improving the performance of polyurethane.

[0061] The present invention provides a method for preparing the two-component polyurethane potting adhesive, and the preparation method includes the preparation of component A and the preparation of component B;

[0062] The preparation of component A includes: mixing acryloxy-terminated polyether polyol and polyester polyol to obtain a mixture, dehydrating the mixture, and then mixing the dehydrated mixture, hydroxyl-terminated polybutadiene prepolymer, and initiator to prepare component A;

[0063] The preparation of component B includes: mixing isocyanate and a catalyst to prepare component B.

[0064] When preparing the two-component polyurethane potting adhesive, dehydrating the acryloxy-terminated polyether polyol and polyester polyol with relatively high water content to reduce the influence of moisture on the isocyanate reaction.

[0065] In an embodiment of the present invention, the preparation of component A specifically includes:

[0066] Mix acryloyloxy-terminated polyether polyol and polyester polyol to obtain a mixture. Dehydrate the mixture under vacuum at 100-130°C until the water content is less than 500 ppm. Lower the temperature of the dehydrated mixture to below 50°C, and then mix the cooled mixture, hydroxyl-terminated polybutadiene prepolymer, and initiator to prepare Component A.

[0067] In the examples of the present invention, the preparation of Component B includes:

[0068] Dehydrate the antioxidant, and then mix the dehydrated antioxidant, isocyanate, catalyst, ultraviolet absorber, defoamer, wetting agent, and dispersant to prepare Component B.

[0069] In the examples of the present invention, the step of dehydrating the antioxidant includes:

[0070] Dehydrate the antioxidant under vacuum at 100-130°C until the water content is less than 500 ppm, and wait for the temperature of the dehydrated antioxidant to drop to 40-50°C.

[0071] In the examples of the present invention, when Component B further includes a silane coupling agent, the preparation of Component B includes:

[0072] Dehydrate the antioxidant, and then mix the dehydrated antioxidant, isocyanate, catalyst, ultraviolet absorber, defoamer, wetting agent, dispersant, and silane coupling agent to prepare Component B.

[0073] The present invention provides an application of the described two-component polyurethane potting adhesive in the encapsulation of MINI LED screens.

[0074] In the examples of the present invention, the application of the described two-component polyurethane potting adhesive in the encapsulation of MINI LED screens includes the following steps:

[0075] Provide a MINI LED screen, mix Component A and Component B in a mass ratio of 100:(40-80), and then fill the mixture at the bonding site of the MINI LED screen for curing.

[0076] Using the technical solution of the present invention to mix Component A and Component B in a mass ratio of 100:(40-80) is beneficial to obtaining a two-component polyurethane potting adhesive with light transmittance, high-temperature and high-humidity resistance, yellowing resistance, and small high and low temperature shrinkage rates.

[0077] In the examples of the present invention, Component A and Component B can be mixed at 15-40°C for 3-5 minutes and then used. At this time, Component A and Component B can form a dense crosslinked system, and the strength of the obtained two-component polyurethane potting adhesive product is better.

[0078] In an embodiment of the present invention, after mixing component A and component B, they are filled at the bonding position of the MINILED screen within 2 to 6 hours. It is necessary to use them up within 2 to 6 hours to facilitate construction. If it exceeds 6 hours, the hardness after curing may be too high, making construction difficult.

[0079] In an embodiment of the present invention, the curing temperature is 20 to 30 °C, and the curing time is 3 to 5 hours. The two-component polyurethane encapsulant 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.

[0080] 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.

[0081] Example 1

[0082] A two-component polyurethane potting adhesive, comprising component A and component B; wherein:

[0083] Component A includes acryloxy-terminated polyether polyol, polyester polyol, hydroxyl-terminated polybutadiene prepolymer, and benzoyl peroxide;

[0084] Component B includes isocyanate, zinc isooctanoate, antioxidant, ultraviolet absorber, defoamer, wetting agent, and dispersant.

[0085] The preparation method of the two-component polyurethane potting adhesive includes the following steps:

[0086] (1) Mix 100 g of acryloxy-terminated polyether polyol (molecular weight 1000, functionality 3) and 300 g of polyester polyol (molecular weight 3000, functionality 2) to obtain a mixture. Vacuum dehydrate the mixture at 120 °C until the water content is less than 500 ppm. After the temperature drops to 50 °C, add 200 g of hydroxyl-terminated polybutadiene prepolymer (molecular weight 2000, functionality 2) and 10 g of benzoyl peroxide to prepare component A and fill it into a barrel with nitrogen for standby;

[0087] (2) Vacuum dehydrate 60 g of antioxidant at 120 °C until the water content is less than 500 ppm. After the temperature of the dehydrated antioxidant drops to 45 °C, add 500 g of isocyanate, 80 g of catalyst, 50 g of ultraviolet absorber, 25 g of defoamer, 5 g of wetting agent, and 8 g of dispersant to prepare component B and fill it into a barrel with nitrogen for standby;

[0088] Among them, the polyester polyol is purchased from Evonik 7230; the hydroxyl-terminated polybutadiene prepolymer is purchased from Nippon Soda GI2000; the antioxidant is the commercially available antioxidant 1010 purchased from BASF; the isocyanate is the commercially available hexamethylene diisocyanate purchased from Bayer; the catalyst is zinc isooctanoate; the ultraviolet absorber is the commercially available Tinuvin 328 purchased from BASF; the defoaming agent is the commercially available BYK065 purchased from BYK Chemie; the wetting agent is the commercially available BYK306 purchased from BYK Chemie; the dispersant is the commercially available BYK-110 purchased from BYK Chemie.

[0089] Example 2

[0090] Compared with Example 1, the difference lies in that 300 g of acryloyloxy-terminated polyether polyol, 600 g of polyester polyol, 100 g of hydroxyl-terminated polybutadiene prepolymer, and 20 g of benzoyl peroxide are used when preparing Component A; 50 g of antioxidant, 300 g of isocyanate, 50 g of catalyst, 30 g of ultraviolet absorber, 20 g of defoaming agent, 8 g of wetting agent, and 5 g of dispersant are used when preparing Component B.

[0091] Example 3

[0092] Compared with Example 1, the difference lies in that 900 g of acryloyloxy-terminated polyether polyol, 100 g of polyester polyol, 150 g of hydroxyl-terminated polybutadiene prepolymer, and 15 g of benzoyl peroxide are used when preparing Component A; 110 g of antioxidant, 700 g of isocyanate, 200 g of catalyst, 90 g of ultraviolet absorber, 50 g of defoaming agent, 10 g of wetting agent, and 10 g of dispersant are used when preparing Component B.

[0093] Example 4

[0094] Compared with Example 1, the difference lies in that the molecular weight of the polyester polyol is 2000.

[0095] Example 5

[0096] Compared with Example 1, the difference lies in that the molecular weight of the polyester polyol is 5000.

[0097] Example 6

[0098] Compared with Example 1, the difference lies in that the molecular weight of the acryloyloxy-terminated polyether polyol is 300.

[0099] Example 7

[0100] Compared with Example 1, the difference lies in that the molecular weight of the acryloyloxy-terminated polyether polyol is 2000.

[0101] Example 8

[0102] Compared with Example 1, the difference is that the molecular weight of the hydroxyl-terminated polybutadiene prepolymer is 1000.

[0103] Example 9

[0104] Compared with Example 1, the difference is that the molecular weight of the hydroxyl-terminated polybutadiene prepolymer is 3000.

[0105] Example 10

[0106] Compared with Example 1, the difference is that the A component further contains 25 g of vinyltrimethoxysilane.

[0107] Example 11

[0108] An application of a two-component polyurethane potting adhesive for MINI LED screen encapsulation, comprising the following steps:

[0109] (1) Pour the A component and B component prepared in Example 1 into the glue barrels of the encapsulation equipment respectively, tightly cover the lids of the glue barrels, vacuum-remove the air bubbles in the glue, adjust the glue output ratio of the A component and B component, and mix the A component and B component evenly according to a mass ratio of 100:60 to obtain a two-component polyurethane potting adhesive.

[0110] (2) Fix the MINI LED screen flat on the glass substrate, convey the glass substrate together with the MINI LED screen into the vacuum chamber of the encapsulation equipment, fill the two-component polyurethane potting adhesive obtained in step (1) of the encapsulation, and perform vacuum defoaming and leveling after filling.

[0111] Example 12

[0112] Compared with Example 11, the difference is that the A component and B component are mixed according to a mass ratio of 100:40.

[0113] Example 13

[0114] Compared with Example 11, the difference is that the A component and B component are mixed according to a mass ratio of 100:80.

[0115] Comparative Example 1

[0116] Compared with Example 1, the difference is that unmodified polyether polyol is used instead of acryloxy-terminated polyether polyol. The unmodified polyether polyol is purchased from Dow CP450.

[0117] Comparative Example 2

[0118] Compared with Example 1, the difference is that the A component does not contain hydroxyl-terminated polybutadiene prepolymer.

[0119] Comparative Example 3

[0120] Compared with Example 11, the difference is that the A component and the B component are mixed in a mass ratio of 100:100.

[0121] Comparative Example 4

[0122] Compared with Example 11, the difference is that the A component and the B component are mixed in a mass ratio of 100:150.

[0123] Performance Test

[0124] For the two-component polyurethane potting adhesives of Examples 1-10 and Comparative Examples 1-2, the A component and the B component were mixed and used to encapsulate the MINI LED screen according to the method of Example 11, and the light transmittance, hardness, appearance, high temperature and high humidity resistance performance, yellowing resistance performance, and shrinkage rate were tested. The test results are shown in Table 1.

[0125] According to the methods of Examples 12-13 and Comparative Examples 1-4, the A component and the B component were mixed and used to encapsulate the MINI LED screen, and the light transmittance, hardness, appearance, high temperature and high humidity resistance performance, yellowing resistance performance, and shrinkage rate were tested. The test results are shown in Table 1.

[0126] A commercially available epoxy potting adhesive was used to encapsulate the MINI LED screen, and the light transmittance, hardness, appearance, high temperature and high humidity resistance performance, yellowing resistance performance, and shrinkage rate were tested. The test results are shown in Table 1.

[0127] The encapsulation method of the commercially available epoxy potting adhesive is as follows:

[0128] The MINI LED screen was flatly fixed on the glass substrate, and the glass substrate together with the MINI LED screen was conveyed into the vacuum chamber of the encapsulation equipment, and the commercially available epoxy potting adhesive (Huitian 6302 epoxy resin potting adhesive) was filled. After filling, vacuum degassing and leveling were carried out.

[0129] Light transmittance test method: Conducted according to the method of GB / T 2410-2008.

[0130] Hardness test method: Conducted according to the method of GB / T 2411-2008.

[0131] High temperature and high humidity resistance performance test method: Tested according to the methods of GB / T 2423-2008 and GB / T 4708-2008. The MINI LED screen was placed in a high temperature and high humidity test chamber for double 85 tests.

[0132] Yellowing resistance performance: Tested according to GB / T 39822-2021. The MINI LED screen was placed under ultraviolet irradiation at a wavelength of 340 nm for testing.

[0133] High and low temperature shrinkage rate test method: Conducted according to the method of GB / T 39818-2021.

[0134] Table 1 Performance test results of the two-component polyurethane potting adhesives of Examples 1-13 and Comparative Examples 1-4 and a commercially available epoxy potting adhesive

[0135]

[0136]

[0137] As can be seen from Table 1, compared with the commercially available epoxy potting adhesive, the two-component polyurethane potting adhesives provided in Examples 1-10 of the present invention have better light transmittance than the commercially available epoxy potting adhesive, and the test results of the double 85 test, yellowing resistance test and high and low temperature shrinkage rate test are also better than those of the commercially available epoxy potting adhesive, indicating that the two-component polyurethane potting adhesive provided by the present invention is beneficial to improving light transmittance, high temperature and high humidity resistance and yellowing resistance, and has a small high and low temperature shrinkage rate, and the appearance is flat and beautiful.

[0138] From the test results of Example 1, Example 4 and Example 5, it can be seen that the higher the molecular weight of the polyester polyol, the higher the hardness of the two-component polyurethane potting adhesive.

[0139] From Example 1, Example 6 and Example 7, it can be seen that the molecular weight of the acryloxy-terminated polyether polyol will affect the hardness and high and low temperature resistance of the two-component polyurethane potting adhesive.

[0140] From Example 1, Example 8 and Example 9, it can be seen that when using a hydroxyl-terminated polybutadiene prepolymer with an average molecular weight of 1000-3000, the two-component polyurethane potting adhesive has good light transmittance, high temperature and high humidity resistance and yellowing resistance.

[0141] From Example 1 and Example 10, it can be seen that adding a small amount of vinyltrimethoxysilane can adjust the hardness of the two-component polyurethane potting adhesive.

[0142] From Example 1, Example 6, Example 7 and Comparative Examples 3-4, it can be seen that the greater the mass ratio of Component A to Component B, the smaller the hardness of the two-component polyurethane potting adhesive. When the mass ratio of Component A to Component B exceeds 100:(40-80), the test results of the light transmittance, high temperature and high humidity resistance and yellowing resistance of the two-component polyurethane potting adhesive become worse.

[0143] From Example 1, Example 12 and Example 13, and from Example 1 and Comparative Examples 1-2, it can be seen that using an unmodified polyether polyol to replace the acryloxy-terminated polyether polyol, or not using the hydroxyl-terminated polybutadiene prepolymer, the light transmittance, high temperature and high humidity resistance, yellowing resistance and high and low temperature shrinkage rate of the two-component polyurethane potting adhesive all become worse.

[0144] The above are only exemplary embodiments of the present invention, and thus do 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, characterized in that, The two-component polyurethane potting adhesive comprises component A and component B; wherein: Component A comprises, by mass parts: 10-90 parts of acryloxy-terminated polyether polyol, 10-60 parts of polyester polyol, 10-20 parts of hydroxyl-terminated polybutadiene prepolymer, and 1-2 parts of initiator; Component B comprises, by mass parts: 30-70 parts of isocyanate and 5-20 parts of catalyst.

2. The two-component polyurethane potting adhesive according to claim 1, wherein, The initiator of the acryloxy-terminated polyether polyol is 1,4-butanediol; and / or, The average functionality of the acryloxy-terminated polyether polyol is 3, and the average molecular weight is 300-2000; and / or, The initiator of the polyester polyol is adipic acid; and / or, The average functionality of the polyester polyol is 2, and the average molecular weight is 2000-5000; and / or, The average functionality of the hydroxyl-terminated polybutadiene prepolymer is 2, and the average molecular weight is 1000-3000; and / or, The initiator comprises benzoyl peroxide; and / or, The isocyanate comprises hexamethylene diisocyanate or isophorone diisocyanate; and / or, The catalyst comprises an organic zinc catalyst, and the organic zinc catalyst comprises zinc isooctanoate.

3. The two-component polyurethane potting adhesive according to claim 1, wherein Component B further comprises 5-11 parts of antioxidant, 3-9 parts of ultraviolet absorber, 2-5 parts of defoamer, 0.5-1 part of wetting agent, and 0.5-1 part of dispersant.

4. The two-component polyurethane potting adhesive according to claim 3, characterized in that, Component A further comprises 2-4 parts of silane coupling agent, and the silane coupling agent comprises vinyltrimethoxysilane.

5. A method for preparing a two-component polyurethane potting adhesive according to any one of claims 1 to 4, characterized in that, The preparation method comprises the preparation of component A and the preparation of component B; The preparation of component A comprises: mixing acryloxy-terminated polyether polyol and polyester polyol to obtain a mixture, dehydrating the mixture, and then mixing the dehydrated mixture, hydroxyl-terminated polybutadiene prepolymer and initiator to obtain component A; The preparation of component B comprises: mixing isocyanate and catalyst to obtain component B.

6. The preparation method of the two-component polyurethane potting adhesive according to claim 5, characterized in that, The step of mixing isocyanate and catalyst to obtain component B comprises: Dehydrating the antioxidant, and then mixing the dehydrated antioxidant, isocyanate, catalyst, ultraviolet absorber, defoamer, wetting agent and dispersant to obtain component B.

7. The preparation method of the two-component polyurethane potting adhesive according to claim 6, characterized in that, The step of mixing isocyanate and catalyst to obtain component B comprises: Dehydrating the antioxidant, and then mixing the dehydrated antioxidant, isocyanate, catalyst, ultraviolet absorber, defoamer, wetting agent, dispersant and silane coupling agent to obtain component B.

8. Application of the two-component polyurethane potting adhesive according to any one of claims 1 to 5 in the encapsulation of MINI LED screens.

9. The application of the two-component polyurethane potting adhesive according to claim 8 in the encapsulation of MINI LED screens, characterized in that, Comprising the following steps: Providing a MINI LED screen, mixing component A and component B according to a mass ratio of 100:(40-80), and then filling the mixture at the bonding part of the MINI LED screen for curing.

10. The application of the two-component polyurethane potting adhesive as claimed in claim 8 in the encapsulation of MINI LED screens, characterized in that, Mixing component A and component B at 15-40 °C for 3-5 min; and / or, After mixing component A and component B, fill it at the bonding position of the MINI LED screen within 2 to 6 hours; and / or, The curing parameters are: the curing temperature is 20 to 30 °C, and the curing time is 3 to 5 hours.

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