Low-temperature conductive pressure-sensitive adhesive as well as preparation method and application thereof

Abstract

The invention provides a low-temperature conductive pressure-sensitive adhesive as well as a preparation method and application thereof. The low-temperature conductive pressure-sensitive adhesive comprises the following raw materials: a polyacrylate pressure-sensitive adhesive, conductive metal powder and a modified polyurethane curing agent, the modified polyurethane curing agent comprises a polymerization reaction product of dimer acid diol, diisocyanate and a chain extender, and the content of NCO is 5%-15%. The low-temperature conductive pressure-sensitive adhesive has excellent low-temperature adhesive force and low-temperature flexibility, shows good low-temperature conductive performance, and has a wide application prospect in a working scene with relatively low environment temperature.

Description

Technical Field

[0001] The present invention belongs to the technical field of pressure-sensitive adhesives, and in particular, relates to a low-temperature conductive pressure-sensitive adhesive, a preparation method thereof, and applications in the preparation of pressure-sensitive adhesive tapes, etc. Background Art

[0002] With the rapid development of the manufacturing industry, pressure-sensitive adhesive tape has become the main material for multi-layer composite materials. Pressure-sensitive adhesive tape can be used to prepare adhesive layers ranging from a few microns to more than ten millimeters through precision coating processes. According to different structures, pressure-sensitive adhesive tapes can be divided into single-sided adhesive tapes, double-sided adhesive tapes and multi-layer composite adhesive tapes; according to different adhesive types, they can be divided into pressure-sensitive adhesive systems such as silicone, polyurethane, and acrylic acid; pressure-sensitive adhesives can be coated on substrates or made into adhesive films without substrates. According to different substrates, they can be divided into PET tapes, PI tapes, non-woven tapes, tissue paper tapes, copper foil tapes, conductive cloth tapes, fiber tapes, etc. The application of adhesive films without substrates is also very extensive, such as OCA tapes, etc.; pressure-sensitive adhesives have extremely wide applications, such as 3C mobile phones, computers, Pads, watches, etc., new energy foam double-sided adhesive tapes, automotive tissue paper tapes, household hook tapes, sealing tapes, reinforcing fiber tapes, etc. Pressure-sensitive adhesives usually have initial tack and a certain bonding strength. According to different bonding strengths, pressure-sensitive adhesives are divided into low-viscosity, medium-viscosity, and high-viscosity tapes.

[0003] The glass transition temperature of existing pressure-sensitive adhesives is generally -50℃~0℃, and the operating temperature is usually 15-30℃. Since the viscosity of pressure-sensitive adhesives is often affected by the ambient temperature, the higher the temperature, the more the pressure-sensitive adhesive turns to a viscous flow state, showing high initial viscosity. In practical applications, it is often difficult to control the ambient temperature of use, especially in the central and northern regions, where the temperature often reaches below 0℃. The lower the temperature, the closer it is to the glass transition temperature, the closer it is to a high elastic state, the lower the fluidity, the lower the initial viscosity, and the pressure-sensitive adhesive will debond, lose adhesion, and fail to stick, which seriously affects the adhesive effect of the tape. Lowering Tg and reducing the cross-linking density of the polymer can increase the fluidity of the adhesive to a certain extent, but it will cause the cohesive strength and peel strength of the pressure-sensitive tape to decrease.

[0004] Therefore, there is an urgent need for a conductive pressure-sensitive adhesive tape that can ensure good cohesion and bonding strength and has good wetting properties and adhesion at low temperatures. Summary of the invention

[0005] The purpose of the present invention is to provide a low-temperature conductive pressure-sensitive adhesive, a preparation method and application thereof, so as to overcome the technical problems of debonding, loss of adhesion and failure to adhere caused by the reduced initial viscosity of the existing conductive pressure-sensitive adhesive under low temperature environment.

[0006] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical scheme.

[0007] The first aspect of the present invention provides a low-temperature conductive pressure-sensitive adhesive, whose raw materials include polyacrylate pressure-sensitive adhesive, conductive metal powder and modified polyurethane curing agent in a mass ratio of 100:15:0.5-10.0; wherein the modified polyurethane curing agent includes a polymerization reaction product of dimer acid diol, diisocyanate and chain extender, wherein the NCO content is 5%-15%.

[0008] In one embodiment, the molecular weight of the polyacrylate pressure-sensitive adhesive is 220,000 to 380,000, and the solid content is 45 to 48%;

[0009] In one embodiment, the conductive metal powder includes conductive nickel powder, preferably dendritic conductive nickel powder with D50=12.0 μm.

[0010] In one embodiment, the preparation method of the modified polyurethane curing agent comprises: mixing and reacting a first reaction system comprising dimer acid polyol, diisocyanate and chain extender in a mass ratio of 100:40 to 100:0.2 to 4 at 60 to 80°C.

[0011] In one embodiment, the isocyanate includes phenylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate, phenylene diisocyanate, and the like, but is not limited thereto.

[0012] In one embodiment, the chain extender includes ethylene glycol, 1,4-butanediol or trihydroxypropane, etc., but is not limited thereto.

[0013] In one embodiment, the raw material of the conductive pressure sensitive adhesive further includes a solvent, such as an organic solvent such as ethyl acetate.

[0014] The second aspect of the present invention provides a method for preparing a low-temperature conductive pressure-sensitive adhesive, comprising:

[0015] A first reaction system comprising dimer acid polyol, diisocyanate and chain extender in a mass ratio of 100:40 to 100:0.2 to 4 is mixed and reacted at 60 to 80° C. to prepare a modified polyurethane curing agent;

[0016] At least the modified polyurethane curing agent is fully mixed with polyacrylate pressure-sensitive adhesive, conductive metal powder and solvent, wherein the mass ratio of polyacrylate pressure-sensitive adhesive, conductive metal powder and modified polyurethane curing agent is 100:15:0.5-10.0.

[0017] In one embodiment, the method specifically includes: reacting a second reaction system comprising a reaction monomer, an initiator and a solvent at 60-65°C for 2-7h, then heating to 70-75°C for 0.5-2h, and then heating to 80-85°C for 0.5-2h to obtain the polyacrylate pressure-sensitive adhesive, wherein the mass ratio of the reaction monomer to the initiator is 100:1-5, and the reaction monomer includes acrylic acid, methyl acrylate, butyl acrylate, isooctyl acrylate, hydroxybutyl acrylate and tetrahydrofuran acrylate in a mass ratio of 2-5:1-3:35-45:40-60:1-3:3-8.

[0018] Furthermore, the molecular weight MW of the polyacrylate pressure-sensitive adhesive is 220,000 to 380,000, and the solid content is 45 to 48%.

[0019] Further, the isocyanate includes phenylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate or phenylene diisocyanate, etc., but is not limited thereto.

[0020] Furthermore, the chain extender includes ethylene glycol, 1,4-butanediol or trihydroxypropane, etc., but is not limited thereto.

[0021] Furthermore, the solvent includes ethyl acetate and the like, but is not limited thereto.

[0022] The third aspect of the present invention also provides a low-temperature conductive pressure sensitive adhesive, which is prepared by the preparation method of the low-temperature conductive pressure sensitive adhesive.

[0023] A fourth aspect of the present invention provides a conductive pressure-sensitive adhesive film formed from the low-temperature conductive pressure-sensitive adhesive.

[0024] A fifth aspect of the present invention provides a conductive adhesive tape, comprising a conductive cloth and a pressure-sensitive adhesive film, wherein the pressure-sensitive adhesive film is bonded to at least one side surface of the conductive cloth; and the pressure-sensitive adhesive film is formed by the low-temperature conductive pressure-sensitive adhesive.

[0025] In one embodiment, the pressure-sensitive adhesive film is bonded to both opposite surfaces of the conductive cloth.

[0026] In one embodiment, the pressure-sensitive adhesive film has a thickness of 1 to 50 μm.

[0027] A sixth aspect of the present invention provides a method for preparing a conductive adhesive tape, comprising:

[0028] The low-temperature conductive pressure-sensitive adhesive is made into a pressure-sensitive adhesive film;

[0029] The pressure-sensitive adhesive film is attached to at least one side of the conductive cloth, and a pressure of 0.1 to 0.3 MPa is applied, and then the conductive cloth is aged at a temperature of 50 to 60°C.

[0030] The seventh aspect of the present invention provides a method for preparing a modified polyurethane, comprising: mixing dimer acid polyol, diisocyanate and a chain extender, and heating the mixture under stirring to react to obtain a modified polyurethane containing a dimer acid segment.

[0031] Specifically, the synthetic route involved in the preparation method can be expressed as:

[0032] HO-(R1-O-R1) n -OH+NCO-R2-NCO→NCO-R2-NHCO-O-(R1-O-R1) n -O-CONH-R2-NCO (1)

[0034] HO-(R1-O-R1) n -OH+NCO-R2-NCO→NCO-R2-NHCO-O-(R1-O-R1) n -O-CONH-R2-NHCO-O-R3-O-CONH-R2-NHCO-O-(R1-O-R1) n -O-CONH-R2-NCO (2)

[0035] Wherein, R1 is a C1-C6 alkyl straight chain segment; n=50-3000.

[0036] R2 is any one of diphenyl, phenyl, isophorone, dicyclohexyl, phenylene, and cyclohexylene.

[0037] R3 is a C2-C6 alkyl straight chain segment.

[0038] Further, the isocyanate may be selected from but not limited to any one or more of phenylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate and phenylene diisocyanate.

[0039] Furthermore, the dimer acid polyol can be selected from but not limited to BY3022 or BY3026.

[0040] Furthermore, the chain extender may be selected from but not limited to any one or a combination of ethylene glycol, 1,4-butanediol and trihydroxypropane.

[0041] Furthermore, the mass ratio of the dimer acid polyol, the diisocyanate and the chain extender is 100:40 to 100:0.2 to 4.

[0042] Furthermore, the heating temperature is 60-80°C.

[0043] Furthermore, the stirring condition is 100-120 rpm.

[0044] The eighth aspect of the present invention provides a modified polyurethane prepared by the preparation method of the modified polyurethane.

[0045] Furthermore, in the modified polyurethane, the NCO content is 5% to 15%.

[0046] The ninth aspect of the present invention provides the use of the modified polyurethane as a curing agent in the preparation of a conductive pressure sensitive adhesive.

[0047] The tenth aspect of the present invention provides a polyurethane curing agent, which at least includes the modified polyurethane.

[0048] The eleventh aspect of the present invention provides a conductive pressure-sensitive adhesive, which is prepared by reacting the aforementioned polyurethane curing agent, conductive nickel powder, and pressure-sensitive adhesive glue.

[0049] Exemplarily, the preparation method of a conductive pressure-sensitive adhesive provided by the present invention specifically includes: first, adding the pressure-sensitive adhesive glue, conductive nickel powder and the polyurethane curing agent to an organic solvent, stirring and mixing them evenly, and filtering; then scraping and coating them on a release film to form an adhesive film, and then rolling and laminating them on both sides of a conductive cloth; finally, after aging, the conductive pressure-sensitive adhesive is prepared.

[0050] Furthermore, the mass ratio of the pressure-sensitive adhesive, the conductive nickel powder and the polyurethane curing agent is 100:15:0.5-10.0.

[0051] Furthermore, the organic solvent is ethyl acetate.

[0052] Furthermore, the conductive nickel powder is a dendritic conductive nickel powder with D50=12.0 μm.

[0053] Furthermore, the stirring speed is 500-1000 rpm, and the stirring time is 40-60 min.

[0054] Furthermore, the filter screen used for filtering is 150 mesh.

[0055] Furthermore, the roller pressing pressure is 0.1-0.3 MPa.

[0056] Furthermore, the thickness of the conductive cloth is 15 μm.

[0057] Furthermore, the aging conditions include aging at 50° C. for 48 hours.

[0058] Exemplarily, the preparation method of the pressure-sensitive adhesive includes: after mixing the reaction monomers, adding an initiator and ethyl acetate in sequence and mixing them evenly to form a mixture; taking one-third of the mixture by weight, heating it to a first temperature under nitrogen protection and stirring it for 20 to 60 minutes, and then starting to drop the remaining mixture, the dropwise addition is completed within 2 to 7 hours, and then continuing the reaction for 1 to 3 hours, and then heating it to a second temperature for reaction for 0.5 to 2 hours, and then heating it to a third temperature until the reaction is completed.

[0059] Furthermore, the molecular weight MW of the polyacrylate pressure-sensitive adhesive is 220,000 to 380,000, and the solid content is 45 to 48%.

[0060] Furthermore, the reactive monomer is a combination of acrylic acid, methyl acrylate, butyl acrylate, isooctyl acrylate, hydroxybutyl acrylate and tetrahydrofuran acrylate.

[0061] Preferably, the reactive monomers include the following components, in parts by mass: 3 parts of acrylic acid, 5 parts of methyl acrylate, 40 parts of butyl acrylate, 45 parts of isooctyl acrylate, 2 parts of hydroxybutyl acrylate and 5 parts of tetrahydrofuran acrylate.

[0062] Furthermore, the initiator is AIBN.

[0063] Furthermore, the mass ratio of the initiator to the reaction monomer is 3.5:100.

[0064] Furthermore, the temperatures of the first temperature condition, the second temperature condition, and the third temperature condition are increased sequentially, for example, they can be 60-65°C, 70-75°C, and 80-85°C, respectively.

[0065] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0066] 1. The present invention introduces dimer acid segments into the molecular chain of the polyurethane curing agent, so that it has excellent wettability and flexibility, and can produce high adhesion on the surface of base materials such as metals and polar plastics. The present invention prepares a conductive pressure-sensitive adhesive with excellent low-temperature adhesion by mixing and coating a synthesized modified polyurethane curing agent with a polyacrylate pressure-sensitive adhesive, a conductive nickel powder, and a solvent, and has low-temperature flexibility and low-temperature adhesion, thereby improving the use performance of the conductive pressure-sensitive adhesive.

[0067] 2. The conductive pressure-sensitive adhesive provided by the technical solution of the present invention can still maintain high initial adhesion performance at temperatures below 0°C (0 to -20°C), so that the conductive pressure-sensitive adhesive product will not experience debonding, loss of adhesion, or problems such as failure to adhere at low temperatures; and it will not affect the cohesive strength and peel strength of the conductive pressure-sensitive adhesive tape. DETAILED DESCRIPTION

[0068] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are 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.

[0069] Unless otherwise specified, the test materials and reagents used in the following examples can be obtained from commercial sources.

[0070] If no specific techniques or conditions are specified in the examples, they can be carried out according to the techniques or conditions described in the literature in the art or according to the product instructions.

[0071] Example 1

[0072] This embodiment provides a conductive pressure-sensitive adhesive T-1, and the specific steps include:

[0073] S1. Providing a polyurethane curing agent;

[0074] In a 250mL three-necked flask, 100g of dimer acid diol BY3022, 80g of MDI, and 4g of chain extender 1,4-butanediol were added, and the temperature was raised to 80°C under nitrogen and stirring at 100-120rpm. The reaction was performed for 2.5 hours to synthesize modified polyurethane curing agent A-1. The NCO content was 10.68% after titration test.

[0075] S2. Provide pressure-sensitive adhesive;

[0076] In a 500mL four-necked flask, 3 parts of acrylic acid, 5 parts of methyl acrylate, 40 parts of butyl acrylate, 45 parts of isooctyl acrylate, 2 parts of hydroxybutyl acrylate and 5 parts of tetrahydrofuran acrylate were mixed to obtain a mixed monomer, and then the initiator AIBN was mixed according to the weight ratio of AIBN: mixed monomer = 3.5:100, and then ethyl acetate was added to the mixed monomer according to the weight ratio of ethyl acetate: mixed monomer = 1:1. One third of the weight of the above mixture was added to a four-necked flask, nitrogen was introduced, and the mixture was stirred at 65°C for 30 minutes, with a stirring speed of 100rpm, and the temperature, stirring and nitrogen were maintained, and then the remaining mixture was added dropwise, and the addition was completed within 4 hours, and then the reaction was continued for 2 hours, and then the temperature was raised to 75°C for 1 hour, and then the temperature was raised to 80°C for 1 hour to prepare a polyacrylate pressure-sensitive adhesive S-1. After testing, the molecular weight of S-1 was 243,000 and the solid content was 47.9%.

[0077] S3. Provide conductive pressure sensitive adhesive;

[0078] 100 g of the pressure-sensitive adhesive S-1 prepared above, 15 g of dendritic conductive nickel powder with a particle size of D50=12.0 μm, and 3 g of the modified polyurethane curing agent A-1 synthesized above, and 100 g of solvent ethyl acetate are added, stirred at 500-1000 rpm for 40-60 min to mix evenly, and filtered with a 150-mesh filter to prepare glue; then a scraper with a thickness of 100 μm is used to scrape the prepared glue on a 50 μm PET release film to form a glue film with a dry glue thickness of 25 μm, and then it is laminated on a 15 μm conductive cloth with a laminating roller pressure of 0.1-0.3 MPa, and then placed in a 50°C curing oven for curing for 48 hours to prepare a conductive pressure-sensitive adhesive T-1.

[0079] Example 2

[0080] This embodiment provides a conductive pressure sensitive adhesive T-2, and the specific steps include:

[0081] S1. Providing a polyurethane curing agent;

[0082] In a 250mL three-necked flask, 100g of dimer acid diol BY3022, 80g of MDI, and 0.2g of chain extender 1,4-butanediol were added, and the temperature was raised to 80°C under nitrogen and stirring at 100-120rpm. The reaction was performed for 2.5 hours to synthesize modified polyurethane curing agent A-2. The NCO content was 13.01% after titration test.

[0083] S2. Provide pressure-sensitive adhesive;

[0084] In a 500mL four-necked flask, 3 parts of acrylic acid, 5 parts of methyl acrylate, 40 parts of butyl acrylate, 45 parts of isooctyl acrylate, 2 parts of hydroxybutyl acrylate and 5 parts of tetrahydrofuran acrylate were mixed to obtain a mixed monomer, and then the initiator AIBN was mixed according to the weight ratio of AIBN: mixed monomer = 3.5:100, and then ethyl acetate was added to the mixed monomer according to the weight ratio of ethyl acetate: mixed monomer = 1:1. One third of the weight of the above mixture was added to a four-necked flask, nitrogen was introduced, and the mixture was stirred at 65°C for 30 minutes, with a stirring speed of 100rpm, and the temperature, stirring and nitrogen were maintained, and then the remaining mixture was added dropwise, and the addition was completed within 4 hours, and then the reaction was continued for 2 hours, and then the temperature was raised to 75°C for 1 hour, and then the temperature was raised to 80°C for 1 hour to prepare a polyacrylate pressure-sensitive adhesive S-1. After testing, the molecular weight of S-1 was 243,000 and the solid content was 47.9%.

[0085] S3. Provide conductive pressure sensitive adhesive;

[0086] The prepared pressure-sensitive adhesive S1100g, 15g of dendritic conductive nickel powder with a particle size of D50=12.0um, and 3g of the modified polyurethane curing agent A-2 synthesized above are added with 100g of solvent ethyl acetate, stirred at 500-1000rpm for 40-60min to mix evenly, and filtered with a 150-mesh filter to prepare glue; then a scraper with a thickness of 100um is used to scrape the prepared glue on a 50um PET release film to form a glue film with a dry glue thickness of 25u, and then it is laminated on a 15u conductive cloth with a laminating roller pressure of 0.1-0.3MPa, and then placed in a 50°C curing oven for curing for 48 hours to prepare a conductive pressure-sensitive adhesive T-2.

[0087] Example 3

[0088] This embodiment provides a conductive pressure-sensitive adhesive T-3, and the specific steps include:

[0089] S1. Providing a polyurethane curing agent;

[0090] In a 250mL three-necked flask, add 100g of dimer acid diol BY3022, 50g of TDI, and 2g of chain extender trihydroxypropane. Heat to 80°C under nitrogen and stirring at 100-120rpm. React for 2.5 hours to synthesize modified polyurethane curing agent A-3. The NCO content is 12.92% after titration test.

[0091] S2. Provide pressure-sensitive adhesive;

[0092] 3 parts of acrylic acid, 5 parts of methyl acrylate, 40 parts of butyl acrylate, 45 parts of isooctyl acrylate, 2 parts of hydroxybutyl acrylate and 5 parts of tetrahydrofuran acrylate are mixed to obtain a mixed monomer, and then the initiator AIBN is mixed according to the weight ratio of AIBN: mixed monomer = 3.5:100, and then ethyl acetate is added to the mixed monomer according to the weight ratio of ethyl acetate: mixed monomer = 1:1. One third of the weight of the above mixture is added to a four-necked flask, nitrogen is introduced, and the reaction is stirred at 65°C for 30 minutes, the stirring speed is 100rpm, and the temperature, stirring and nitrogen are maintained, and then the remaining mixture is added dropwise, and the addition is completed within 4 hours, and then the reaction is continued for 2 hours, and then the temperature is raised to 75°C for 1 hour, and then the temperature is raised to 80°C for 1 hour to prepare a polyacrylate pressure-sensitive adhesive S-1. After testing, the molecular weight of S-1 is 243,000 and the solid content is 47.9%.

[0093] S3. Provide conductive pressure sensitive adhesive;

[0094] 100 g of the pressure-sensitive adhesive S-1 prepared above, 15 g of dendritic conductive nickel powder with a particle size of D50=12.0 μm, and 3 g of the modified polyurethane curing agent A-3 synthesized above are added with 100 g of solvent ethyl acetate, stirred at 500-1000 rpm for 40-60 min to mix evenly, and filtered with a 150-mesh filter to prepare glue; then a scraper with a thickness of 100 um is used to scrape the prepared glue on a 50 μm PET release film to form a glue film with a dry glue thickness of 25 μm, and then it is laminated on a 15 μm conductive cloth with a laminating roller pressure of 0.1-0.3 MPa, and then placed in a 50°C curing oven for curing for 48 hours to prepare a conductive pressure-sensitive adhesive T-3.

[0095] Example 4

[0096] This embodiment provides a conductive pressure sensitive adhesive T-4, and the specific steps include:

[0097] S1. Providing a polyurethane curing agent;

[0098] In a 250mL three-necked flask, 100g of dimer acid diol BY3022, 70g of IPDI, and 2g of chain extender trihydroxypropane were added, and the temperature was raised to 80°C under nitrogen and stirring at 100-120rpm. The reaction was performed for 2.5 hours to synthesize modified polyurethane curing agent A-4. The NCO content was 12.54% after titration test.

[0099] S2. Provide pressure-sensitive adhesive;

[0100] In a 500mL four-necked flask, 3 parts of acrylic acid, 5 parts of methyl acrylate, 40 parts of butyl acrylate, 45 parts of isooctyl acrylate, 2 parts of hydroxybutyl acrylate and 5 parts of tetrahydrofuran acrylate were mixed to obtain a mixed monomer, and then the initiator AIBN was mixed according to the weight ratio of AIBN: mixed monomer = 3.5:100, and then ethyl acetate was added to the mixed monomer according to the weight ratio of ethyl acetate: mixed monomer = 1:1. One third of the weight of the above mixture was added to a four-necked flask, nitrogen was introduced, and the mixture was stirred at 65°C for 30 minutes, with a stirring speed of 100rpm, and the temperature, stirring and nitrogen were maintained, and then the remaining mixture was added dropwise, and the addition was completed within 4 hours, and then the reaction was continued for 2 hours, and then the temperature was raised to 75°C for 1 hour, and then the temperature was raised to 80°C for 1 hour to prepare a polyacrylate pressure-sensitive adhesive S-1. After testing, the molecular weight of S-1 was 243,000 and the solid content was 47.9%.

[0101] S3. Provide conductive pressure sensitive adhesive;

[0102] 100 g of the pressure-sensitive adhesive S-1 prepared above, 15 g of dendritic conductive nickel powder with a particle size of D50=12.0 um, and 3 g of the modified polyurethane curing agent A-4 synthesized above, and 100 g of solvent ethyl acetate are added, stirred at 500-1000 rpm for 40-60 min to mix evenly, and filtered with a 150-mesh filter to prepare glue; then a scraper with a thickness of 100 μm is used to scrape the prepared glue on a 50 μm PET release film to form a glue film with a dry glue thickness of 25 μm, and then it is laminated on a 15 μm conductive cloth with a laminating roller pressure of 0.1-0.3 MPa, and then placed in a 50°C curing oven for curing for 48 hours to prepare a conductive pressure-sensitive adhesive T-4.

[0103] Example 5

[0104] This embodiment provides a conductive pressure-sensitive adhesive T-5, which is different from Embodiment 1 only in the step of preparing the polyurethane curing agent in S1, and the rest is the same.

[0105] The specific steps of S1 for preparing the polyurethane curing agent include:

[0106] In a 250mL three-necked flask, 100g of dimer acid diol BY3022, 80g of MDI, and 4g of chain extender 1,4-butanediol were added. The temperature was raised to 60°C under nitrogen and stirring at 100-120rpm. The reaction was performed for 5.5 hours to synthesize modified polyurethane curing agent A-5. The NCO content was 9.93% after titration test.

[0107] Example 6

[0108] This embodiment provides a conductive pressure-sensitive adhesive T-6, which is different from Embodiment 1 only in the step of preparing the polyurethane curing agent in S1, and the rest is the same.

[0109] The specific steps of S1 for preparing the polyurethane curing agent include:

[0110] In a 250mL three-necked flask, 100g of dimer acid diol BY3022, 40g of MDI, and 2g of chain extender 1,4-butanediol were added, and the temperature was raised to 80°C under nitrogen and stirring at 100-120rpm. The reaction was performed for 2.5 hours to synthesize modified polyurethane curing agent A-6. The NCO content was 6.02% after titration test.

[0111] Example 7

[0112] This embodiment provides a conductive pressure-sensitive adhesive T-7, which is different from the embodiment 1 only in that the steps of preparing the conductive pressure-sensitive adhesive in S3 are different, and the specific steps include:

[0113] S3. Provide conductive pressure sensitive adhesive;

[0114] 100 g of the pressure-sensitive adhesive S-1 prepared above, 15 g of dendritic conductive nickel powder with a particle size of D50=12.0 μm, 0.5 g of the modified polyurethane curing agent A-1 synthesized above, and 100 g of solvent ethyl acetate were added, stirred at 500-1000 rpm for 40-60 min to mix evenly, and filtered with a 150-mesh filter to prepare glue; then a scraper with a thickness of 100 μm was used to scrape the prepared glue on a 50 μm PET release film to form a glue film with a thickness of 25 μm, and then it was laminated on a 15 μm conductive cloth with a laminating roller pressure of 0.1-0.3 MPa, and then placed in a 50°C curing oven for curing for 48 hours to prepare a conductive pressure-sensitive adhesive T-7.

[0115] Example 8

[0116] This embodiment provides a conductive pressure-sensitive adhesive T-8, which is different from the embodiment 1 only in that the steps of preparing the conductive pressure-sensitive adhesive in S3 are different, and the specific steps include:

[0117] S3. Provide conductive pressure sensitive adhesive;

[0118] 100 g of the pressure-sensitive adhesive S-1 prepared above, 15 g of dendritic conductive nickel powder with a particle size of D50=12.0 μm, and 10 g of the modified polyurethane curing agent A-1 synthesized above, and 100 g of solvent ethyl acetate are added, stirred at 500-1000 rpm for 40-60 min to mix evenly, and filtered with a 150-mesh filter to prepare glue; then a scraper with a thickness of 100 μm is used to scrape the prepared glue on a 50 μm PET release film to form a glue film with a dry glue thickness of 25 μm, and then it is laminated on a 15 μm conductive cloth with a laminating roller pressure of 0.1-0.3 MPa, and then placed in a 50°C curing oven for curing for 48 hours to prepare a conductive pressure-sensitive adhesive T-8.

[0119] Comparative Example 1

[0120] This comparative example provides a conductive pressure-sensitive adhesive T′-1, and the specific steps include:

[0121] 100 g of the pressure-sensitive adhesive S-1 prepared in Example 1, 15 g of dendritic conductive nickel powder with a particle size of D50=12.0 μm, 3 g of commercially available urethane curing agent LA-75 (calculated as A′-1), and 100 g of solvent ethyl acetate were added, stirred at 500-1000 rpm for 40-60 min to mix evenly, and filtered with a 150-mesh filter to prepare a glue; then a scraper with a thickness of 100 μm was used to scrape the prepared glue on a 50 μm PET release film to form a glue film with a dry glue thickness of 25 u, and then it was laminated on a 15 μm conductive cloth with a laminating roller pressure of 0.1-0.3 MPa, and then placed in a 50°C curing oven for curing for 48 hours to prepare a conductive pressure-sensitive adhesive T′-1.

[0122] Comparative Example 2

[0123] This comparative example provides a conductive pressure-sensitive adhesive T′-2, and the specific steps include:

[0124] S1. Providing a polyurethane curing agent;

[0125] In a 250mL three-necked flask, 100g of dimer acid diol BY3022, 20g of MDI, and 2.0g of chain extender 1,4-butanediol were added, and the temperature was raised to 80°C under nitrogen and stirring at 100-120rpm. The reaction was performed for 2.5 hours to synthesize modified polyurethane curing agent A'-2. The NCO content was 1.69% after titration test.

[0126] The other steps are the same as those in Example 1 to prepare the conductive pressure-sensitive adhesive T′-2.

[0127] Comparative Example 3

[0128] This comparative example provides a conductive pressure-sensitive adhesive T′-3, and the specific steps include:

[0129] S1. Providing a polyurethane curing agent;

[0130] In a 250mL three-necked flask, 100g of dimer acid diol BY3022, 120g of MDI, and 2g of chain extender 1,4-butanediol were added. The temperature was raised to 80°C under nitrogen and stirring at 100-120rpm. The reaction was performed for 2.5 hours to synthesize modified polyurethane curing agent A'-3. The NCO content was 15.62% after titration test.

[0131] The other steps are the same as those in Example 1 to prepare the conductive pressure-sensitive adhesive T′-3.

[0132] Comparative Example 4

[0133] This comparative example provides a conductive pressure-sensitive adhesive T′-4, wherein S1 and S2 in the preparation method are the same as those in Example 1. The specific steps of S3 include:

[0134] S3. Provide conductive pressure sensitive adhesive;

[0135] 100 g of the pressure-sensitive adhesive S-1 prepared above, 15 g of dendritic conductive nickel powder with a particle size of D50=12.0 μm, and 0.2 g of the modified polyurethane curing agent A-1 synthesized above, and 100 g of solvent ethyl acetate are added, stirred at 500-1000 rpm for 40-60 min to mix evenly, and filtered with a 150-mesh filter to prepare glue; then a scraper with a thickness of 100 μm is used to scrape the prepared glue on a 50 μm PET release film to form a glue film with a dry glue thickness of 25 μm, and then it is laminated on a 15 μm conductive cloth with a laminating roller pressure of 0.1-0.3 MPa, and then placed in a 50°C curing oven for curing for 48 hours to prepare a conductive pressure-sensitive adhesive T′-4.

[0136] Comparative Example 5

[0137] This comparative example provides a conductive pressure-sensitive adhesive T′-5, wherein S1 and S2 in the preparation method are the same as those in Example 1. The specific steps of S3 include:

[0138] S3. Provide conductive pressure sensitive adhesive;

[0139] 100 g of the pressure-sensitive adhesive S-1 prepared above, 15 g of dendritic conductive nickel powder with a particle size of D50=12.0 μm, and 15 g of the modified polyurethane curing agent A-1 synthesized above, and 100 g of solvent ethyl acetate are added, stirred at 500-1000 rpm for 40-60 min to mix evenly, and filtered with a 150-mesh filter to prepare glue; then a scraper with a thickness of 100 μm is used to scrape the prepared glue on a 50 μm PET release film to form a glue film with a dry glue thickness of 25 μm, and then it is laminated on a 15 μm conductive cloth with a laminating roller pressure of 0.1-0.3 MPa, and then placed in a 50°C curing oven for curing for 48 hours to prepare a conductive pressure-sensitive adhesive T′-5.

[0140] Comparative Example 6

[0141] This comparative example provides a conductive pressure-sensitive adhesive T′-6, and the specific steps include:

[0142] S1. Providing a polyurethane curing agent;

[0143] In a 250mL three-necked flask, add 100g BY3022, 20g MDI, 0g chain extender 1,4-butanediol, and heat to 80°C under nitrogen and stirring at 100-120rpm. React for 2.5 hours to synthesize modified polyurethane curing agent A'-6. The NCO content is 3.11% after titration test.

[0144] The other steps are the same as those in Example 1 to prepare the conductive pressure sensitive adhesive T′-6.

[0145] Comparative Example 7

[0146] This comparative example provides a conductive pressure-sensitive adhesive T′-7, and the specific steps include:

[0147] S1. Providing a polyurethane curing agent;

[0148] In a 250mL three-necked flask, add 100g BY3022, 0g MDI, 2g chain extender 1,4-butanediol, and heat to 80°C under nitrogen and stirring at 100-120rpm. React for 2.5 hours to synthesize modified polyurethane curing agent A'-7. The NCO content is 0% after titration test.

[0149] The other steps are the same as those in Example 1 to prepare the conductive pressure-sensitive adhesive T′-7.

[0150] Comparative Example 8

[0151] This comparative example provides a conductive pressure-sensitive adhesive T′-8, and the specific steps include:

[0152] S1. Providing a polyurethane curing agent;

[0153] In a 250mL three-necked flask, 0g BY3022, 40g MDI, 100g chain extender 1,4-butanediol were added, and the temperature was raised to 80°C under nitrogen and stirring at 100-120rpm. The reaction was performed for 2.5 hours to synthesize modified polyurethane curing agent A′-8. The NCO content was 0% after titration test.

[0154] The other steps are the same as those in Example 1 to prepare the conductive pressure sensitive adhesive T′-8.

[0155] Comparative Example 9

[0156] This comparative example provides a conductive pressure-sensitive adhesive T′-9, and the specific steps include:

[0157] S1. Providing a polyurethane curing agent;

[0158] In a 250mL three-necked flask, 100g of phthalic anhydride polyester polyol, 120g of MDI, and 4g of chain extender 1,4-butanediol were added. The temperature was raised to 80°C under nitrogen and stirring at 100-120rpm. The reaction was performed for 2.5 hours to synthesize modified polyurethane curing agent A'-9. The NCO content was 13.62% after titration test.

[0159] The other steps are the same as those in Example 1 to prepare the conductive pressure-sensitive adhesive T′-9.

[0160] Performance Test:

[0161] 1. Conductivity test

[0162] Horizontal resistance test: Place the adhesive surface of the conductive pressure-sensitive adhesives T-1 to T-8, T′-1 to T′-8 prepared in the above embodiments and comparative examples under two copper electrodes with a distance of 30 mm, and then use two chucks of a resistance tester to clamp the two copper electrodes to test the horizontal resistance.

[0163] Vertical resistance test: The conductive pressure-sensitive adhesives T-1 to T-8, T′-1 to T′-8 prepared in the above embodiments and comparative examples were cut into 25mm*25mm areas, and then attached between two 25mm*25mm*25mm copper block electrodes. The two copper electrodes were then clamped with two chucks of a resistance tester to test the vertical resistance.

[0164] 2. Ring initial adhesion test

[0165] According to GB / T 31125-2014, the conductive pressure-sensitive adhesives T-1 to T-8 and T′-1 to T′-8 prepared in the above embodiments and comparative examples were placed at -20°C, -10°C, 0°C, 10°C, and 25°C for 30 minutes to test their annular initial adhesion to the SUS plate using a constant temperature tensile machine.

[0166] 3.180° peel force test

[0167] According to GB / T 2792-2014, a constant temperature tensile testing machine was used to test the conductive pressure-sensitive adhesives T-1 to T-8 and T′-1 to T′-8 prepared in the above embodiments and comparative examples, respectively, at different temperatures of -20°C, -10°C, 0°C, 10°C, and 25°C for 30 min to test the 180° peeling force of the pressure-sensitive adhesive on the SUS plate.

[0168] The test results are shown in Table 1 and Table 2.

[0169] Table 1 Performance test results of conductive pressure sensitive adhesives T-1 to T-8 prepared in Example

[0170]

[0171] Table 2 Performance test results of conductive pressure sensitive adhesive T'-1 to T'-9 prepared in comparative example

[0172]

[0173]

[0174] By comparing the performance test results of Table 1 and Table 2, it can be seen that the conductive pressure-sensitive adhesive prepared by using the modified polyurethane curing agent synthesized by the present invention has the same level of conductive performance as the comparative example, and the formulations of Examples T-1 to T-8 have obvious technical advantages in terms of room temperature and low temperature annular initial adhesion and 180° peeling force performance; Comparative Example T'-1 uses a conventional curing agent with a high crosslinking density, and the peeling force and annular initial adhesion under low temperature conditions are relatively low, T'-2 and T'-7 have higher low-temperature annular initial adhesion, but the room temperature annular initial adhesion of the colloid is too low, it is too soft at room temperature, and the cohesive strength is low; T'-3 to T'-6 have low and low temperature and high temperature annular initial adhesion and 180° peeling force values, which are at the level of medium and low viscosity pressure-sensitive adhesives, and T'-8 has a poor cohesion of the prepared pressure-sensitive adhesive because the curing agent has no crosslinking reaction active point and is a liquid substance, which is equivalent to a plasticizer, and the annular initial adhesion and 180° peeling force at low temperature are very low, and it does not form a film at room temperature and has no adhesive performance. T'-9 is a curing agent prepared from phthalic anhydride polyester polyol. Because the molecule contains a benzene ring structure, it has high rigidity and high cohesion, which improves the adhesion to the polar plastic substrate. It exhibits moderate initial adhesion and high peeling force at room temperature of 25°C, but at low temperatures of <10°C, the initial adhesion and peeling force are low, and it cannot meet the requirements of use under low temperature conditions.

[0175] The description of the above embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the explanation of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A low temperature conductive pressure sensitive adhesive, characterized in that: The raw materials of the low-temperature conductive pressure-sensitive adhesive include polyacrylate pressure-sensitive adhesive, conductive metal powder and modified polyurethane curing agent in a mass ratio of 100:15:0.5-10.0; wherein the modified polyurethane curing agent includes a polymerization reaction product of dimer acid diol, diisocyanate and chain extender, wherein the NCO content is 5%-15%.

2. The low temperature conductive pressure sensitive adhesive according to claim 1, characterized in that: The polyacrylate pressure-sensitive adhesive has a molecular weight of 220,000 to 380,000 and a solid content of 45 to 48%. And / or, the conductive metal powder comprises conductive nickel powder, preferably dendritic conductive nickel powder with D50=12.0 μm; And / or, the preparation method of the modified polyurethane curing agent comprises: mixing and reacting a first reaction system comprising dimer acid polyol, diisocyanate and chain extender in a mass ratio of 100:40 to 100:0.2 to 4 at 60 to 80° C.; and / or, the isocyanate comprises phenylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate or phenylene diisocyanate; And / or, the chain extender includes ethylene glycol, 1,4-butanediol or trihydroxypropane.

3. The low temperature conductive pressure sensitive adhesive according to claim 1, characterized in that: The raw materials of the conductive pressure sensitive adhesive also include a solvent.

4. A method for preparing a low-temperature conductive pressure-sensitive adhesive, characterized in that: include: A first reaction system comprising dimer acid polyol, diisocyanate and chain extender in a mass ratio of 100:40 to 100:0.2 to 4 is mixed and reacted at 60 to 80° C. to prepare a modified polyurethane curing agent; At least the modified polyurethane curing agent is fully mixed with polyacrylate pressure-sensitive adhesive, conductive metal powder and solvent, wherein the mass ratio of polyacrylate pressure-sensitive adhesive, conductive metal powder and modified polyurethane curing agent is 100:15:0.5-10.

0.

5. The preparation method according to claim 4, characterized in that: The method specifically comprises: reacting a second reaction system comprising a reaction monomer, an initiator and a solvent at 60-65° C. for 4-6 hours, then heating the system to 70-75° C. for 0.5-2 hours, and then heating the system to 80-85° C. for 0.5-2 hours, to obtain the polyacrylate pressure-sensitive adhesive, wherein the mass ratio of the reaction monomer to the initiator is 100:1-5, and the reaction monomer comprises acrylic acid, methyl acrylate, butyl acrylate, isooctyl acrylate, hydroxybutyl acrylate and tetrahydrofuran acrylate in a mass ratio of 2-5:1-3:35-45:40-60:1-3:3-8; And / or, the molecular weight MW of the polyacrylate pressure-sensitive adhesive is 220,000 to 380,000, and the solid content is 45 to 48%; and / or, the isocyanate comprises phenylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate or phenylene diisocyanate; and / or, the chain extender comprises ethylene glycol, 1,4-butanediol or trihydroxypropane; And / or, the solvent comprises ethyl acetate.

6. A low temperature conductive pressure sensitive adhesive, characterized in that: It is prepared by the method described in any one of claims 4-5.

7. A conductive pressure-sensitive adhesive film, characterized in that: It is formed by the low-temperature conductive pressure-sensitive adhesive described in any one of claims 1-3 and 6.

8. A conductive adhesive tape, comprising a conductive tape and a pressure-sensitive adhesive film, wherein the pressure-sensitive adhesive film is bonded to at least one side surface of the conductive tape; characterized in that: The pressure-sensitive adhesive film is formed by the low-temperature conductive pressure-sensitive adhesive according to any one of claims 1 to 3 and 6.

9. The conductive tape according to claim 8, characterized in that: The pressure-sensitive adhesive film is bonded to both opposite surfaces of the conductive cloth; and / or the pressure-sensitive adhesive film has a thickness of 1 to 50 μm.

10. A method for preparing a conductive adhesive tape, characterized in that: include: The low-temperature conductive pressure-sensitive adhesive according to any one of claims 1 to 3 and 6 is made into a pressure-sensitive adhesive film; The pressure-sensitive adhesive film is attached to at least one side of the conductive cloth, and a pressure of 0.1 to 0.3 MPa is applied, and then the conductive cloth is aged at a temperature of 50 to 60°C.

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