Polyurethane for ACF adhesive film as well as preparation method and application of polyurethane

Abstract

The invention discloses polyurethane for an ACF adhesive film. The polyurethane is prepared from the following raw materials in parts by weight: 80 to 100 parts of polytetramethylene ether glycol, 60 to 80 parts of modified isocyanate, 8 to 10 parts of a chain extender, 1 to 3 parts of a catalyst and 40 to 80 parts of a solvent, the modified isocyanate is prepared from the following raw materials: 1, 3, 5-triallyl isocyanurate, 1, 6-hexanedithiol and 1, 5-naphthalene diisocyanate, and the modified isocyanate is prepared from the following raw materials: 1, 3, 5-triallyl isocyanurate, 1, 6-hexanedithiol and 1, 5-naphthalene diisocyanate. According to the polyurethane for the ACF adhesive film provided by the invention, the stability and the reliability of the polyurethane in a high-temperature and high-humidity environment are improved, the polyurethane is applied to the ACF adhesive film, the requirements of high-end application fields such as the ACF adhesive film and the like can be met, and the polyurethane has a wide market prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of anisotropic conductive adhesive films, and in particular relates to polyurethane for ACF adhesive films and a preparation method and application thereof. Background Art

[0002] Polyurethane has been widely used in many fields due to its excellent mechanical properties, wear resistance, oil resistance, tear resistance, chemical corrosion resistance, radiation resistance and good adhesion. However, polyurethane has obvious shortcomings in high temperature and high humidity resistance. The high temperature resistance of polyurethane generally does not exceed 80℃. Above 100℃, the material will soften and deform, and the mechanical properties will be significantly weakened. The short-term use temperature does not exceed 120℃. This characteristic seriously limits the application of polyurethane in high temperature and high humidity environments, especially in ACF films.

[0003] ACF film, or anisotropic conductive film, mainly includes two parts: resin adhesive and conductive particles. It is a key material widely used in the field of electronic packaging. In terms of high temperature resistance, ACF film needs to remain stable during high temperature welding or curing to ensure the reliability of the connection. However, when the temperature exceeds the temperature resistance limit of the ACF film, the conductive particles may cause the conductive properties to decrease or even be lost due to diffusion, melting or transfer. This seriously affects the application of ACF film in high temperature environments. At the same time, in a high humidity environment, the ACF film may undergo chemical reactions such as hydrolysis or oxidation, resulting in reduced or complete loss of conductive properties. This moisture sensitivity problem not only affects the reliability of the ACF film, but may also cause electronic products to fail in a humid environment. However, existing polyurethane materials are prone to performance degradation in high temperature and high humidity environments, such as softening, deformation, and decreased adhesion. Therefore, the application of existing polyurethane materials in ACF films affects the conductive properties and reliability of the ACF films. Summary of the invention

[0004] The purpose of the present invention is to overcome the problem of poor high temperature and high humidity resistance of polyurethane in the prior art, and to provide a polyurethane for ACF film to improve its stability and reliability in high temperature and high humidity environments, thereby meeting the needs of high-end application fields such as ACF film.

[0005] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0006] In a first aspect, the present invention provides a polyurethane for ACF film, comprising the following raw materials in parts by weight: 80-100 parts of polytetramethylene ether glycol, 60-80 parts of modified isocyanate, 8-10 parts of chain extender, 1-3 parts of catalyst, and 40-80 parts of solvent;

[0007] The modified isocyanate is prepared by using 1,3,5-triallyl isocyanurate, 1,6-hexanedithiol and 1,5-naphthalene diisocyanate as raw materials.

[0008] Furthermore, the preparation method of the modified isocyanate comprises the following steps:

[0009] S1. Add 1,3,5-triallyl isocyanurate, 1,6-hexanedithiol and benzophenone to toluene, mix evenly, irradiate under ultraviolet light for 1-3 hours, concentrate under reduced pressure, wash and recrystallize to obtain an intermediate;

[0010] S2. Add 1,5-naphthalene diisocyanate to toluene and dissolve it by ultrasonication. Then add the intermediate and stannous octoate, mix them evenly, degas in vacuum, and heat them programmatically. After the reaction is completed, concentrate under reduced pressure, filter, wash and dry to obtain modified isocyanate.

[0011] Furthermore, in step S1, the ratio of the amount of 1,3,5-triallyl isocyanurate, 1,6-hexanedithiol, benzophenone and toluene is (2.4-2.5) g: (4.5-4.8) g: (0.05-0.1) g: 100 mL.

[0012] Furthermore, in step S2, the ratio of the amount of the intermediate, 1,5-naphthalene diisocyanate, stannous octoate and toluene is (7.1-7.5) g: (6.3-6.5) g: (0.05-0.1) g: 100 mL.

[0013] Further, in step S2, the programmed temperature rising process is:

[0014] Raise the temperature from room temperature to 30°C and keep at 30°C for 3h;

[0015] Raise the temperature from 30°C to 60°C, and keep at 60°C for 0.5-1.5h;

[0016] Raise the temperature from 60°C to 80°C and keep at 80°C for 4-6 hours;

[0017] Raise the temperature from 80°C to 100°C, and keep at 100°C for 0.5-5h;

[0018] Raise the temperature from 100°C to 120°C and keep at 120°C for 0.5-1.5h.

[0019] Furthermore, the chain extender is one or more of resveratrol, citronellol, abietic acid, and caffeic acid;

[0020] The catalyst is bismuth neodecanoate and / or N-methylimidazole;

[0021] The solvent is one or more of toluene, xylene, n-butanol, isobutanol, and butyl acetate.

[0022] Furthermore, the chain extender is prepared by mixing resveratrol and citronellol in a mass ratio of (2-8):3.

[0023] In a second aspect, the present invention provides a method for preparing a polyurethane for an ACF film, comprising the following steps: adding polytetramethylene ether glycol, modified isocyanate, and a catalyst to a solvent, stirring and heating to 100-115°C, and removing the solvent by vacuum for 1-2 hours while stirring; cooling to 40-50°C, adding a chain extender, continuously stirring and maintaining the reaction temperature at 75-80°C, reacting for 4-5 hours, and obtaining a polyurethane for an ACF film.

[0024] In a third aspect, the present invention provides an application of a polyurethane for an ACF film in an ACF film.

[0025] Furthermore, the preparation method of the ACF film comprises the following steps:

[0026] According to weight, 40-100 parts of polyurethane, 20-40 parts of epoxy resin, 10-20 parts of nitrile rubber, 8-14 parts of conductive microspheres, 5-15 parts of fillers and 20-100 parts of low-boiling point solvent are weighed in sequence, and mixed evenly in the weighing order, and then 1-10 parts of curing agent are added and mixed evenly to obtain anisotropic conductive adhesive slurry; the anisotropic conductive adhesive slurry is applied on a release film to evaporate the low-boiling point solvent, and the release film is removed to obtain an ACF adhesive film.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. In the present invention, the raw material composition of the polyurethane used for the ACF adhesive film includes modified isocyanate, which uses 1,3,5-triallyl isocyanurate and 1,6-hexanedithiol to undergo a thiol click reaction to generate an intermediate, and then reacts with 1,5-naphthalene diisocyanate to generate a modified isocyanate. The modified isocyanate contains a triazine ring, a thioether bond, and a naphthalene ring, and reacts with polytetramethylene ether glycol to generate a polyurethane, and the crosslinking density of the internal hybrid network increases, which limits the space for the free movement of the polyurethane chain, increases the energy required for the polyurethane chain to move and rotate, and increases the glass transition temperature, thereby enhancing the high temperature resistance of the polyurethane; and in a high humidity environment, it is not easy to undergo a hydrolysis reaction or structural damage phenomenon, which effectively improves the high humidity resistance of the polyurethane. At the same time, the polyurethane contains 1,6-hexanedithiol and polytetramethylene ether glycol, which gives the polyurethane a higher flexibility, so that the polyurethane still has excellent elastic properties.

[0029] 2. The polyurethane for ACF film provided by the present invention selects one or more of resveratrol, citronellol, rosin acid, and caffeic acid as chain extenders, which can react with free radicals of polyurethane to increase the crosslinking density of polyurethane, enhance the thermal stability of polyurethane, reduce the penetration of water, and thus improve the stability of polyurethane in a humid environment; further preferably, a mixture of resveratrol and citronellol in a specific mass ratio is used as the chain extender, and the two synergistically enhance the synergy and work together to improve the high temperature and high humidity resistance of polyurethane.

[0030] 3. The polyurethane for ACF film provided by the present invention uses bismuth neodecanoate and / or N-methylimidazole as a catalyst to reduce the occurrence of side reactions, make the generated polyurethane molecular chain structure more regular, enhance the cohesion and stability of the polyurethane, reduce the performance degradation caused by molecular chain breakage in a high temperature and high humidity environment, and help improve the high temperature and humidity resistance of the polyurethane.

[0031] 4. The polyurethane provided by the present invention can be applied to ACF film to significantly improve the high temperature and high humidity resistance of the ACF film, has excellent bonding performance, and has broad market prospects. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Preparation Example 1-3 provides a method for preparing a modified isocyanate.

[0034] Preparation Example 1

[0035] This preparation example provides a method for preparing a modified isocyanate, comprising the following steps:

[0036] S1. Add 2.4 g of 1,3,5-triallyl isocyanurate, 4.5 g of 1,6-hexanedithiol, and 0.05 g of benzophenone into 100 mL of toluene, mix evenly, and irradiate at a wavelength of 360 nm and an irradiation intensity of 20 mW / cm 2 After irradiation under ultraviolet light for 1 h, the product was concentrated under reduced pressure, washed, and recrystallized to obtain an intermediate;

[0037] S2. Add 6.3 g of 1,5-naphthalene diisocyanate to 100 mL of toluene and dissolve it by ultrasonication. Then add 7.1 g of the intermediate and 0.05 g of stannous octoate. After uniform mixing and vacuum degassing, perform programmed temperature increase (the programmed temperature increase process is: 30°C / 3h, 60°C / 0.5h, 80°C / 4h, 100°C / 0.5h, 120°C / 0.5h). Specifically, the programmed temperature increase program is shown in Table 1. After the reaction is completed, concentrate under reduced pressure, filter, wash and dry to obtain modified isocyanate.

[0038] Table 1 Heating program

[0039] Heating process Insulation process Room temperature -30℃ Keep warm at 30℃ for 3h 30℃-60℃ Keep warm at 60℃ for 0.5h 60℃-80℃ Keep warm at 80℃ for 4h 80℃-100℃ Keep warm at 100℃ for 0.5h 100℃-120℃ Keep warm at 120℃ for 0.5h

[0040] Preparation Example 2

[0041] This preparation example provides a method for preparing a modified isocyanate, comprising the following steps:

[0042] S1. Add 2.45 g of 1,3,5-triallyl isocyanurate, 4.65 g of 1,6-hexanedithiol, and 0.08 g of benzophenone into 100 mL of toluene, mix evenly, and irradiate at a wavelength of 380 nm and an irradiation intensity of 23 mW / cm 2 After irradiation under ultraviolet light for 2 h, the product was concentrated under reduced pressure, washed, and recrystallized to obtain an intermediate;

[0043] S2. Add 6.4 g of 1,5-naphthalene diisocyanate to 100 mL of toluene and dissolve it by ultrasonication. Then add 7.3 g of the intermediate and 0.08 g of stannous octoate. After uniform mixing and vacuum degassing, perform programmed temperature increase (the programmed temperature increase process is: 30°C / 3h, 60°C / 1h, 80°C / 5h, 100°C / 3h, 120°C / 1h). Specifically, the programmed temperature increase program is shown in Table 2. After the reaction is completed, concentrate under reduced pressure, filter, wash and dry to obtain modified isocyanate.

[0044] Table 2 Heating program

[0045] Heating process Insulation process Room temperature -30℃ Keep warm at 30℃ for 3h 30℃-60℃ Keep warm at 60℃ for 1h 60℃-80℃ Keep warm at 80℃ for 5h 80℃-100℃ Keep warm at 100℃ for 3h 100℃-120℃ Keep warm at 120℃ for 1h

[0046] Preparation Example 3

[0047] This preparation example provides a method for preparing a modified isocyanate, comprising the following steps:

[0048] S1. Add 2.5 g of 1,3,5-triallyl isocyanurate, 4.8 g of 1,6-hexanedithiol, and 0.1 g of benzophenone into 100 mL of toluene, mix evenly, and irradiate at a wavelength of 400 nm and an irradiation intensity of 25 mW / cm 2 After irradiation under ultraviolet light for 3 h, the product was concentrated under reduced pressure, washed, and recrystallized to obtain an intermediate;

[0049] S2. Add 6.5 g of 1,5-naphthalene diisocyanate to 100 mL of toluene and dissolve it by ultrasonication. Then add 7.5 g of the intermediate and 0.1 g of stannous octoate. After uniform mixing and vacuum degassing, perform programmed temperature increase (the programmed temperature increase process is: 30°C / 3h, 60°C / 1.5h, 80°C / 6h, 100°C / 5h, 120°C / 1.5h). Specifically, the programmed temperature increase program is shown in Table 3. After the reaction is completed, concentrate under reduced pressure, filter, wash and dry to obtain modified isocyanate.

[0050] Table 3 Heating program

[0051] Heating process Insulation process Room temperature -30℃ Keep warm at 30℃ for 3h 30℃-60℃ Keep warm at 60℃ for 1.5h 60℃-80℃ Keep warm at 80℃ for 6h 80℃-100℃ Keep warm at 100℃ for 5h 100℃-120℃ Keep warm at 120℃ for 1.5h

[0052] Examples 1-7 and Comparative Examples 1-3 all provide a polyurethane for ACF film and a preparation method thereof.

[0053] Example 1

[0054] This embodiment provides a polyurethane for ACF film, comprising the following raw materials in parts by weight: 80 parts of polytetramethylene ether glycol, 60 parts of modified isocyanate, 8 parts of chain extender, 1 part of catalyst, and 40 parts of solvent;

[0055] Wherein, the modified isocyanate is prepared by Preparation Example 1; the chain extender is resveratrol; the catalyst is bismuth neodecanoate; and the solvent is toluene.

[0056] This embodiment also provides a method for preparing polyurethane for ACF film, comprising the following steps:

[0057] Add polytetramethylene ether glycol, modified isocyanate and catalyst to the solvent, stir and heat to 100°C, and remove the solvent under vacuum for 1 hour while stirring; cool to 40°C, add chain extender, continue stirring and maintain the reaction temperature at 75°C, react for 4 hours to obtain polyurethane.

[0058] Example 2

[0059] This embodiment provides a polyurethane for ACF film, comprising the following raw materials in parts by weight: 90 parts of polytetramethylene ether glycol, 70 parts of modified isocyanate, 9 parts of chain extender, 2 parts of catalyst, and 60 parts of solvent;

[0060] Wherein, the modified isocyanate is prepared by Preparation Example 2; the chain extender is rosin acid; the catalyst is N-methylimidazole; and the solvent is xylene.

[0061] This embodiment also provides a method for preparing polyurethane for ACF film, comprising the following steps:

[0062] Add polytetramethylene ether glycol, modified isocyanate and catalyst to the solvent, stir and heat to 110°C, and remove the solvent under vacuum for 1.5 hours while stirring; cool to 45°C, add chain extender, continue stirring and maintain the reaction temperature at 78°C, react for 4.5 hours to obtain polyurethane.

[0063] Example 3

[0064] This embodiment provides a polyurethane for ACF film, comprising the following raw materials in parts by weight: 100 parts of polytetramethylene ether glycol, 80 parts of modified isocyanate, 10 parts of chain extender, 3 parts of catalyst, and 80 parts of solvent;

[0065] Among them, the modified isocyanate is prepared by Preparation Example 3; the chain extender is caffeic acid; the catalyst is obtained by mixing bismuth neodecanoate and N-methylimidazole in a mass ratio of 1:1; and the solvent is obtained by mixing xylene and butyl acetate in a mass ratio of 1:1.

[0066] This embodiment also provides a method for preparing polyurethane for ACF film, comprising the following steps:

[0067] Add polytetramethylene ether glycol, modified isocyanate and catalyst to the solvent, stir and heat to 115°C, and remove the solvent under vacuum for 2 hours while stirring; cool to 50°C, add chain extender, continue stirring and maintain the reaction temperature at 80°C, react for 5 hours to obtain polyurethane.

[0068] Example 4

[0069] This embodiment provides a polyurethane for ACF film, comprising the following raw materials in parts by weight: 80 parts of polytetramethylene ether glycol, 60 parts of modified isocyanate, 8 parts of chain extender, 1 part of catalyst, and 40 parts of solvent;

[0070] Wherein, the modified isocyanate is prepared by Preparation Example 1; the chain extender is citronellol; the catalyst is bismuth neodecanoate; and the solvent is toluene.

[0071] This embodiment also provides a method for preparing polyurethane for ACF film, comprising the following steps:

[0072] Add polytetramethylene ether glycol, modified isocyanate and catalyst to the solvent, stir and heat to 100°C, and remove the solvent under vacuum for 1 hour while stirring; cool to 40°C, add chain extender, continue stirring and maintain the reaction temperature at 75°C, react for 4 hours to obtain polyurethane.

[0073] Example 5

[0074] This embodiment provides a polyurethane for ACF film, comprising the following raw materials in parts by weight: 80 parts of polytetramethylene ether glycol, 60 parts of modified isocyanate, 8 parts of chain extender, 1 part of catalyst, and 40 parts of solvent;

[0075] The modified isocyanate is prepared by Preparation Example 1; the chain extender is obtained by mixing resveratrol and citronellol in a mass ratio of 2:1; the catalyst is bismuth neodecanoate; and the solvent is toluene.

[0076] This embodiment also provides a method for preparing polyurethane for ACF film, comprising the following steps:

[0077] Add polytetramethylene ether glycol, modified isocyanate and catalyst to the solvent, stir and heat to 100°C, and remove the solvent under vacuum for 1 hour while stirring; cool to 40°C, add chain extender, continue stirring and maintain the reaction temperature at 75°C, react for 4 hours to obtain polyurethane.

[0078] Example 6

[0079] This embodiment provides a polyurethane for ACF film, comprising the following raw materials in parts by weight: 80 parts of polytetramethylene ether glycol, 60 parts of modified isocyanate, 8 parts of chain extender, 1 part of catalyst, and 40 parts of solvent;

[0080] Wherein, the modified isocyanate is prepared by Preparation Example 1; the chain extender is resveratrol; the catalyst is N-methylimidazole; and the solvent is toluene.

[0081] This embodiment also provides a method for preparing polyurethane for ACF film, comprising the following steps:

[0082] Add polytetramethylene ether glycol, modified isocyanate and catalyst to the solvent, stir and heat to 100°C, and remove the solvent under vacuum for 1 hour while stirring; cool to 40°C, add chain extender, continue stirring and maintain the reaction temperature at 75°C, react for 4 hours to obtain polyurethane.

[0083] Example 7

[0084] This embodiment provides a polyurethane for ACF film, comprising the following raw materials in parts by weight: 80 parts of polytetramethylene ether glycol, 60 parts of modified isocyanate, 8 parts of chain extender, 1 part of catalyst, and 40 parts of solvent;

[0085] The modified isocyanate is prepared by Preparation Example 1; the chain extender is resveratrol; the catalyst is a mixture of bismuth neodecanoate and N-methylimidazole in a mass ratio of 2:1; and the solvent is toluene.

[0086] This embodiment also provides a method for preparing polyurethane for ACF film, comprising the following steps:

[0087] Add polytetramethylene ether glycol, modified isocyanate and catalyst to the solvent, stir and heat to 100°C, and remove the solvent under vacuum for 1 hour while stirring; cool to 40°C, add chain extender, continue stirring and maintain the reaction temperature at 75°C, react for 4 hours to obtain polyurethane.

[0088] Comparative Example 1

[0089] This comparative example provides a polyurethane for ACF film, which is different from Example 1 only in that an equal mass of 1,5-naphthalene diisocyanate is used to replace the modified isocyanate, as follows:

[0090] A polyurethane for ACF film, comprising the following raw materials in parts by weight: 80 parts of polytetramethylene ether glycol, 60 parts of 1,5-naphthalene diisocyanate, 8 parts of a chain extender, 1 part of a catalyst, and 40 parts of a solvent;

[0091] The chain extender is resveratrol; the catalyst is bismuth neodecanoate; and the solvent is toluene.

[0092] This comparative example also provides a method for preparing polyurethane for ACF film, comprising the following steps:

[0093] Add polytetramethylene ether glycol, 1,5-naphthalene diisocyanate and a catalyst to a solvent, stir and heat to 100°C, and remove the solvent under vacuum for 1 hour while stirring; cool to 40°C, add a chain extender, continue stirring and maintain the reaction temperature at 75°C, react for 4 hours to obtain polyurethane.

[0094] Comparative Example 2

[0095] This comparative example provides a polyurethane for ACF film, which is different from Example 1 only in that 1,4-butanediol is used as a chain extender, as follows:

[0096] A polyurethane for ACF film, comprising the following raw materials in parts by weight: 80 parts of polytetramethylene ether glycol, 60 parts of modified isocyanate, 8 parts of chain extender, 1 part of catalyst, and 40 parts of solvent;

[0097] Wherein, the modified isocyanate is prepared by Preparation Example 1; the chain extender is 1,4-butanediol; the catalyst is bismuth neodecanoate; and the solvent is toluene.

[0098] This comparative example also provides a method for preparing polyurethane for ACF film, comprising the following steps:

[0099] Add polytetramethylene ether glycol, modified isocyanate and catalyst to the solvent, stir and heat to 100°C, and remove the solvent under vacuum for 1 hour while stirring; cool to 40°C, add chain extender, continue stirring and maintain the reaction temperature at 75°C, react for 4 hours to obtain polyurethane.

[0100] Comparative Example 3

[0101] This comparative example provides a polyurethane for ACF film, which is different from Example 1 only in that dioctyltin dilaurate is used as a catalyst, as follows:

[0102] A polyurethane for ACF film, comprising the following raw materials in parts by weight: 80 parts of polytetramethylene ether glycol, 60 parts of modified isocyanate, 8 parts of chain extender, 1 part of catalyst, and 40 parts of solvent;

[0103] Wherein, the modified isocyanate is prepared by Preparation Example 1; the chain extender is resveratrol; the catalyst is dioctyltin dilaurate; and the solvent is toluene.

[0104] This comparative example also provides a method for preparing polyurethane for ACF film, comprising the following steps:

[0105] Add polytetramethylene ether glycol, modified isocyanate and catalyst to the solvent, stir and heat to 100°C, and remove the solvent under vacuum for 1 hour while stirring; cool to 40°C, add chain extender, continue stirring and maintain the reaction temperature at 75°C, react for 4 hours to obtain polyurethane.

[0106] Application Examples

[0107] The polyurethanes prepared in Examples 1-7 and Comparative Examples 1-3 were respectively used to prepare ACF films according to the following method to prepare Application Examples 1-7 and Application Comparative Examples 1-3, and the polyurethane (PU306) was used to replace the polyurethane of the present invention to obtain Application Comparative Example 4. Specifically, the preparation method of the ACF film is as follows:

[0108] According to weight, 40 parts of polyurethane, 40 parts of bisphenol A epoxy resin (E-51), 20 parts of nitrile rubber (NBR-2707), 8 parts of nickel-plated conductive microspheres (Ni@PS, particle size of 10 μm), 10 parts of filler (nano-silica) and 20 parts of low-boiling point solvent (ethyl acetate) are mixed in order, and then a curing agent (i.e., 5 parts of triethylenetetramine and 5 parts of benzoyl peroxide) is added and mixed evenly to obtain an anisotropic conductive adhesive paste; the anisotropic conductive adhesive paste is applied on a release film, the low-boiling point solvent is volatilized at 80°C for 10 minutes, and then the release film is removed to obtain an ACF film with a thickness of 20 μm.

[0109] Performance Testing

[0110] The ACF film was placed at room temperature (25°C) for 30 minutes, and the film was connected to the printed circuit board and the FPC under the initial pressing conditions (80°C, 1 second, 1.0MPa) and the final pressing conditions (160°C, 5 seconds, 3MPa). Five samples were prepared using the ACF film obtained in Application Example 1; the samples were tested for bonding strength at 90°, 1cm width, and a stretching speed of 50mm / min. Individual adjacent electrodes on the TFT were designed to be U-shaped, bonded to the electrodes on the FPC, and test lines were drawn out to measure the connection resistance by the diode method.

[0111] The ACF films prepared in Application Examples 2-7 and Application Comparative Examples 1-4 were subjected to the same test method, and the on-resistance and bonding strength data obtained were statistically analyzed. The above Application Examples 1-7 and Application Comparative Examples 1-4 were subjected to high temperature and high humidity (85°C, 85% RH, 250H) test and water boiling (95°C, 3H) test, and the performance is shown in Tables 4 and 5.

[0112] Table 4

[0113]

[0114] Table 5

[0115]

[0116]

[0117] It can be seen from Tables 4 and 5 that the ACF film obtained by using Application Examples 1-7 is subjected to high temperature and high humidity (85°C, 85% RH, 250H) test and water boiling (95°C, 3H) test, and the increase in on-resistance is less than 20%, and the decrease in bonding strength is also less than 20%, indicating that the ACF film has strong tolerance in polar environment and very stable performance, which is significantly better than Application Comparative Examples 1-4; it fully demonstrates that the polyurethane of the present invention is applied to the ACF film, which can effectively improve the high temperature and high humidity resistance of the ACF film.

[0118] The modified isocyanate prepared by using 1,3,5-triallyl isocyanurate, 1,6-hexanedithiol and 1,5-naphthalene diisocyanate as basic raw materials reacts with polytetramethylene ether glycol to generate polyurethane. The modified isocyanate helps to improve the crosslinking density of the polyurethane. By comparing Application Example 1 with Application Comparative Example 1, the on-resistance and bonding strength change rates of the ACF film after high temperature and high humidity are small, and the film has excellent weather resistance.

[0119] The polyurethane prepared with resveratrol or citronellol as chain extender is applied to the ACF film, which is better than the polyurethane prepared with the mixture of resveratrol and citronellol as chain extender applied to the ACF film, that is, comparing Application Example 1, Application Example 4 and Application Example 5, which fully illustrates that the mixture of resveratrol and citronellol is used as a chain extender to introduce more active groups, which can increase the cross-linking density inside the polyurethane and improve the high temperature and high humidity resistance of the polyurethane; in addition, by comparing Application Examples 1, 4-5 and Application Comparative Example 2, it can be seen that the preferred chain extender of the present invention is significantly better than 1,4-butanediol, which further illustrates that the polyurethane of the present invention can effectively ensure that the ACF film still has excellent stability in a polar environment.

[0120] The polyurethane prepared with bismuth neodecanoate or N-methylimidazole as catalyst is applied to the ACF film, which is more effective than the polyurethane prepared with a mixture of bismuth neodecanoate and N-methylimidazole as catalyst applied to the ACF film, that is, comparing Application Example 1, Application Example 6 and Application Example 7, which is sufficient to illustrate that using a mixture of bismuth neodecanoate and N-methylimidazole as a catalyst can significantly reduce the activation energy of the polyurethane polymerization reaction, accelerate the reaction rate, adjust the arrangement and cross-linking degree of the polyurethane molecular chain, and improve the high temperature and high humidity resistance of the polyurethane; at the same time, by comparing Application Examples 1, 6-7 with Application Comparative Example 3, it can be seen that the preferred catalyst of the present invention is significantly better than dioctyltin dilaurate, and is more conducive to enhancing the performance of the polyurethane, and is also conducive to the application of the polyurethane in the ACF film, improving the curing effect of the film, and making the ACF film better suitable for high temperature and high humidity environments.

[0121] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0122] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A polyurethane for ACF film, characterized in that: The method comprises the following raw materials in parts by weight: 80-100 parts of polytetramethylene ether glycol, 60-80 parts of modified isocyanate, 8-10 parts of chain extender, 1-3 parts of catalyst, and 40-80 parts of solvent; The modified isocyanate is prepared by taking 1,3,5-triallyl isocyanurate, 1,6-hexanedithiol and 1,5-naphthalene diisocyanate as raw materials.

2. The polyurethane for ACF film according to claim 1, characterized in that: The preparation method of the modified isocyanate comprises the following steps: S1. Add 1,3,5-triallyl isocyanurate, 1,6-hexanedithiol and benzophenone to toluene, mix evenly, irradiate under ultraviolet light for 1-3 hours, concentrate under reduced pressure, wash and recrystallize to obtain an intermediate; S2. Add 1,5-naphthalene diisocyanate to toluene and dissolve it by ultrasonication. Then add the intermediate and stannous octoate, mix them evenly, degas in vacuum, and heat them programmatically. After the reaction is completed, concentrate under reduced pressure, filter, wash and dry to obtain modified isocyanate.

3. The polyurethane for ACF film according to claim 2, characterized in that: In step S1, the ratio of the amount of 1,3,5-triallyl isocyanurate, 1,6-hexanedithiol, benzophenone and toluene is (2.4-2.5) g: (4.5-4.8) g: (0.05-0.1) g: 100 mL.

4. The polyurethane for ACF film according to claim 2, characterized in that: In step S2, the ratio of the intermediate, 1,5-naphthalene diisocyanate, stannous octoate and toluene is (7.1-7.5) g: (6.3-6.5) g: (0.05-0.1) g: 100 mL.

5. The polyurethane for ACF film according to claim 2, characterized in that: In step S2, the programmed temperature rising process is: Raise the temperature from room temperature to 30°C and keep at 30°C for 3h; Raise the temperature from 30°C to 60°C, and keep at 60°C for 0.5-1.5h; Raise the temperature from 60°C to 80°C and keep at 80°C for 4-6 hours; Raise the temperature from 80°C to 100°C and keep at 100°C for 0.5-5h; Raise the temperature from 100°C to 120°C and keep at 120°C for 0.5-1.5h.

6. The polyurethane for ACF film according to claim 1, characterized in that: The chain extender is one or more of resveratrol, citronellol, abietic acid, and caffeic acid; The catalyst is bismuth neodecanoate and / or N-methylimidazole; The solvent is one or more of toluene, xylene, n-butanol, isobutanol, and butyl acetate.

7. The polyurethane for ACF film according to claim 6, characterized in that: The chain extender is prepared by mixing resveratrol and citronellol in a mass ratio of (2-8):

3.

8. A method for preparing a polyurethane for an ACF adhesive film according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: adding polytetramethylene ether glycol, modified isocyanate and a catalyst into a solvent, stirring and heating to 100-115° C., and removing the solvent by vacuum for 1-2 hours while stirring; cooling to 40-50° C., adding a chain extender, continuously stirring and maintaining the reaction temperature at 75-80° C., reacting for 4-5 hours, and obtaining a polyurethane for an ACF film.

9. Use of the polyurethane for ACF film according to any one of claims 1 to 7 in ACF film.

10. The use according to claim 9, characterized in that: The preparation method of the ACF film comprises the following steps: According to weight, 40-100 parts of polyurethane, 20-40 parts of epoxy resin, 10-20 parts of nitrile rubber, 8-14 parts of conductive microspheres, 5-15 parts of fillers and 20-100 parts of low-boiling point solvent are weighed in sequence, and mixed evenly in the weighing order, and then 1-10 parts of curing agent are added and mixed evenly to obtain anisotropic conductive adhesive slurry; the anisotropic conductive adhesive slurry is applied on a release film to evaporate the low-boiling point solvent, and the release film is removed to obtain an ACF adhesive film.

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