UV (ultraviolet) curing adhesive for FPC (flexible printed circuit) and preparation method thereof
By introducing siloxane glycol epoxy acrylate, trimethylolpropane triacrylate, and Schiff base modified polyurethane acrylate into UV-curable adhesives for FPCs, the problems of high curing shrinkage and insufficient heat resistance have been solved, resulting in an adhesive with low shrinkage and high heat resistance, suitable for high-end electronic devices.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DONGGUAN SHIYOU ADHESIVE MATERIALS CO LTD
- Filing Date
- 2026-02-27
- Publication Date
- 2026-05-05
AI Technical Summary
Existing UV-curable adhesives for FPCs have problems such as high curing shrinkage and insufficient heat resistance, which cause FPC substrate warping and circuit misalignment, failing to meet the requirements of high-end electronic devices.
The method uses aliphatic polyurethane acrylate as the main component, combined with siloxane ethylene glycol epoxy acrylate and trimethylolpropane triacrylate as reactive diluents, introduces Schiff base structure modified polyurethane acrylate, optimizes the photoinitiator composition, reduces curing shrinkage and improves heat resistance.
It achieves low curing shrinkage and good heat resistance, improving the stability and precision of FPC substrates, and is suitable for high-temperature environments.
Smart Images
Figure REF-OBJ-1772173293721-000001
Abstract
Description
Technical Field
[0001] This invention relates to the field of cured adhesives, specifically a UV-curable adhesive for FPC and its preparation method. Background Technology
[0002] Flexible printed circuit boards (FPCs) are widely used in consumer electronics, automotive electronics, and other fields due to their thinness, lightness, and flexibility. The requirements for UV-curable adhesives during their assembly process are becoming increasingly stringent. Current UV-curable adhesives for FPCs are mostly based on aliphatic polyurethane acrylate (PUA) combined with conventional reactive diluents. However, they have the following problems: First, the curing shrinkage rate is too high, which easily leads to warping of the FPC substrate and circuit misalignment, affecting product accuracy. Second, their heat resistance is insufficient; they are prone to softening and deformation under high-temperature soldering and long-term humid and hot service environments, failing to meet the requirements of high-end electronic devices.
[0003] In summary, the preparation of a UV-curable adhesive for FPC is of great significance in order to solve the above problems. Summary of the Invention
[0004] The purpose of this invention is to provide a UV-curable adhesive for FPC and its preparation method, so as to solve the problems raised in the prior art.
[0005] To achieve the above objectives, the present invention provides the following technical solution: A UV-curable adhesive for FPC, the UV-curable adhesive comprising the following components by weight: 60-75 parts aliphatic polyurethane acrylate, 20-25 parts modified polyurethane acrylate, 12-18 parts reactive diluent, 3-6 parts photoinitiator, 1-2 parts antioxidant, and 0.5-2 parts defoamer.
[0006] In a more optimized form, the reactive diluent comprises siloxane ethylene glycol epoxy acrylate and trimethylolpropane triacrylate in a mass ratio of (3~5):1.
[0007] A more optimized method for preparing the siloxane ethylene glycol epoxy acrylate is as follows: (1) Ethylene glycol diglycidyl ether and tetrabutylammonium bromide are mixed, heated to 80~90℃, 3-butenoic acid and polymerization inhibitor are added, and stirring is continued for 2~3 hours to obtain ethylene glycol epoxy acrylate; (2) Ethylene glycol epoxy acrylate and Karstedt catalyst are added to isopropanol and mixed, heated to 65~75℃, tetramethyldisiloxane is added and stirred for 2~4 hours to obtain siloxane ethylene glycol epoxy acrylate.
[0008] In a more optimized form, the raw materials for the ethylene glycol epoxy acrylate include the following components: by mass parts, 10-15 parts ethylene glycol diglycidyl ether, 0.5-1 part tetrabutylammonium bromide, 7-8 parts 3-butenoic acid, and 0.1-0.2 parts polymerization inhibitor; the raw materials for the siloxane ethylene glycol epoxy acrylate include the following components: by mass parts, 8-10 parts ethylene glycol epoxy acrylate, 0.07-0.12 parts Karstedt catalyst, and 3-5 parts tetramethyldisiloxane.
[0009] In this scheme, the epoxy group on ethylene glycol diglycidyl ether reacts with the carboxyl group on 3-butenoic acid under the catalysis of tetrabutylammonium bromide to obtain ethylene glycol epoxy acrylate containing allyl groups; the allyl groups thereon react with the Si-H group on tetramethyldisiloxane under the action of Karstedt catalyst to obtain siloxane ethylene glycol epoxy acrylate.
[0010] A more optimized method for preparing the modified polyurethane acrylate is as follows: (1) p-phenylenediamine and 2,4-dihydroxybenzaldehyde are added to ethanol and mixed, refluxed for 6-8 hours, and recrystallized to obtain p-phenylenediamine-2,4-dihydroxybenzaldehyde Schiff base; (2) isophorone diisocyanate and polyethylene glycol are added to acetone and mixed, dibutyltin dilaurate is added and heated to react, p-phenylenediamine-2,4-dihydroxybenzaldehyde Schiff base and hydroxyethyl acrylate are added to continue the reaction to obtain the modified polyurethane acrylate.
[0011] More optimally, the molar ratio of p-phenylenediamine to 2,4-dihydroxybenzaldehyde is 1:2; the raw materials for the modified polyurethane acrylate include the following components by mass: 25-30 parts isophorone diisocyanate, 13-18 parts polyethylene glycol, 0.5-1.2 parts dibutyltin dilaurate, 8-12 parts p-phenylenediamine-2,4-dihydroxybenzaldehyde Schiff base, and 3-6 parts hydroxyethyl acrylate.
[0012] In a more optimized form, the raw materials for the photoinitiator include methyl benzoate and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide in a mass ratio of (2~3):(1~2).
[0013] A method for preparing a UV-curable adhesive for FPC includes the following steps: mixing aliphatic polyurethane acrylate, reactive diluent and defoamer, heating to 50~60℃, stirring for 1~2 hours, adding modified polyurethane acrylate, photoinitiator and antioxidant and mixing evenly, filtering to obtain the UV-curable adhesive.
[0014] The optimal curing conditions for the UV-curable adhesive are: 30~60mW / cm². 2 Irradiate with UV lamps at a distance of 50~70mm.
[0015] Compared with the prior art, the beneficial effects of the present invention are: In this scheme, aliphatic polyurethane acrylate is used as the main substrate for UV curing; it has good flexibility and good curing speed; however, it has a high curing shrinkage rate. To solve this problem, the scheme further introduces siloxane ethylene glycol epoxy acrylate and trimethylolpropane triacrylate as reactive diluents; the Si-O-Si segments in siloxane ethylene glycol epoxy acrylate have good flexibility and high temperature resistance, which can alleviate the crosslinking stress of multifunctional components and reduce the curing shrinkage rate; trimethylolpropane triacrylate can balance the curing speed.
[0016] The introduction of hydroxyl groups through the reverse ring-opening reaction of the epoxy groups on ethylene glycol epoxy acrylate and the carboxyl groups on 3-butenoic acid can improve compatibility with the main resin and enhance interfacial adhesion with the substrate.
[0017] In this scheme, to prevent the UV-cured adhesive from softening in high-temperature environments, a polyurethane acrylate with a Schiff base is introduced to improve its high-temperature resistance. The amino group on p-phenylenediamine reacts with the aldehyde group on benzaldehyde to form a Schiff base, yielding p-phenylenediamine-2,4-dihydroxybenzaldehyde Schiff base. The hydroxyl group on this base can react with isophorone diisocyanate, thereby introducing a Schiff base structure into the modified polyurethane acrylate and improving its rigidity. In conjunction with siloxane ethylene glycol epoxy acrylate, the heat distortion temperature of the adhesive can be increased, thus improving the stability of the UV-cured adhesive. Detailed Implementation
[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0019] In the following specific embodiments, "parts" refers to parts by weight. It should be noted that there are no special restrictions on the manufacturers of the raw materials involved in this invention. Exemplary examples include: ethylene glycol diglycidyl ether (CAS number 2224-15-9); 3-butenoic acid (CAS number 625-38-7); p-hydroxyanisole (polymerization inhibitor) (CAS number 150-76-5); tetramethyldisiloxane (CAS number 3277-26-7); p-phenylenediamine (CAS number 106-50-3); 2,4-diphenylamine (CAS number 106-50-3); and other related products. The CAS number for hydroxybenzaldehyde is 95-01-2; the CAS number for isophorone diisocyanate is 4098-71-9; the molecular weight of polyethylene glycol is 1000; the model number for aliphatic polyurethane acrylate is RJ422; the CAS number for methyl benzoate is 15206-55-0; the CAS number for 2,4,6-trimethylbenzoyl-diphenylphosphine oxide is 75980-60-8; the defoamer is a polyether-modified silicone defoamer, model number BYK-024; and the antioxidant is antioxidant 1010.
[0020] Example 1: Preparation of a UV-curable adhesive for FPC, comprising the following steps: Pre-preparation: The preparation method of siloxane ethylene glycol epoxy acrylate is as follows: (1) Mix 12 parts of ethylene glycol diglycidyl ether and 0.6 parts of tetrabutylammonium bromide, heat to 90°C, add 8 parts of 3-butenoic acid and 0.1 parts of polymerization inhibitor (p-hydroxyanisole), and continue stirring for 3 hours to obtain ethylene glycol epoxy acrylate; (2) Add 10 parts of ethylene glycol epoxy acrylate and 0.08 parts of Karstedt catalyst to 50 parts of isopropanol and mix, heat to 75°C, add 5 parts of tetramethyldisiloxane and stir for 4 hours to obtain siloxane ethylene glycol epoxy acrylate; The preparation method of modified polyurethane acrylate is as follows: (1) p-phenylenediamine and 2,4-dihydroxybenzaldehyde are added to ethanol and mixed, refluxed for 6 hours, and recrystallized to obtain p-phenylenediamine-2,4-dihydroxybenzaldehyde Schiff base; the molar ratio of p-phenylenediamine and 2,4-dihydroxybenzaldehyde is 1:2; (2) 30 parts of isophorone diisocyanate and 18 parts of polyethylene glycol are added to 100 parts of acetone and mixed, 0.8 parts of dibutyltin dilaurate are added and heated at 80°C for 1.5 hours, 10 parts of p-phenylenediamine-2,4-dihydroxybenzaldehyde Schiff base and 4 parts of hydroxyethyl acrylate are added and the reaction continues for 3 hours to obtain modified polyurethane acrylate; Mix 60 parts aliphatic polyurethane acrylate, 12 parts reactive diluent and 0.7 parts defoamer, heat to 50°C, stir for 1 hour, add 20 parts modified polyurethane acrylate, 4 parts photoinitiator and 1 part antioxidant (antioxidant 1010) and mix evenly, filter to obtain UV-curable adhesive. The reactive diluents include siloxane ethylene glycol epoxy acrylate and trimethylolpropane triacrylate in a mass ratio of 3:1; the photoinitiators include methyl benzoylformate and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide in a mass ratio of 2:1.
[0021] Example 2, preparation of a UV-curable adhesive for FPC, includes the following steps: Pre-preparation: The preparation method of siloxane ethylene glycol epoxy acrylate is as follows: (1) Mix 12 parts of ethylene glycol diglycidyl ether and 0.6 parts of tetrabutylammonium bromide, heat to 90°C, add 8 parts of 3-butenoic acid and 0.1 parts of polymerization inhibitor (p-hydroxyanisole), and continue stirring for 3 hours to obtain ethylene glycol epoxy acrylate; (2) Add 10 parts of ethylene glycol epoxy acrylate and 0.08 parts of Karstedt catalyst to 50 parts of isopropanol and mix, heat to 75°C, add 5 parts of tetramethyldisiloxane and stir for 4 hours to obtain siloxane ethylene glycol epoxy acrylate; The preparation method of modified polyurethane acrylate is as follows: (1) p-phenylenediamine and 2,4-dihydroxybenzaldehyde are added to ethanol and mixed, refluxed for 6 hours, and recrystallized to obtain p-phenylenediamine-2,4-dihydroxybenzaldehyde Schiff base; the molar ratio of p-phenylenediamine and 2,4-dihydroxybenzaldehyde is 1:2; (2) 30 parts of isophorone diisocyanate and 18 parts of polyethylene glycol are added to 100 parts of acetone and mixed, 0.8 parts of dibutyltin dilaurate are added and heated at 80°C for 1.5 hours, 10 parts of p-phenylenediamine-2,4-dihydroxybenzaldehyde Schiff base and 4 parts of hydroxyethyl acrylate are added and the reaction continues for 3 hours to obtain modified polyurethane acrylate; Mix 70 parts aliphatic polyurethane acrylate, 12 parts reactive diluent and 0.7 parts defoamer, heat to 50°C, stir for 1 hour, add 22 parts modified polyurethane acrylate, 4 parts photoinitiator and 1 part antioxidant (antioxidant 1010) and mix evenly, filter to obtain UV-curable adhesive. The reactive diluents include siloxane ethylene glycol epoxy acrylate and trimethylolpropane triacrylate in a mass ratio of 3:1; the photoinitiators include methyl benzoylformate and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide in a mass ratio of 2:1.
[0022] Example 3, preparation of a UV-curable adhesive for FPC, includes the following steps: Pre-preparation: The preparation method of siloxane ethylene glycol epoxy acrylate is as follows: (1) Mix 12 parts of ethylene glycol diglycidyl ether and 0.6 parts of tetrabutylammonium bromide, heat to 90°C, add 8 parts of 3-butenoic acid and 0.1 parts of polymerization inhibitor (p-hydroxyanisole), and continue stirring for 3 hours to obtain ethylene glycol epoxy acrylate; (2) Add 10 parts of ethylene glycol epoxy acrylate and 0.08 parts of Karstedt catalyst to 50 parts of isopropanol and mix, heat to 75°C, add 5 parts of tetramethyldisiloxane and stir for 4 hours to obtain siloxane ethylene glycol epoxy acrylate; The preparation method of modified polyurethane acrylate is as follows: (1) p-phenylenediamine and 2,4-dihydroxybenzaldehyde are added to ethanol and mixed, refluxed for 6 hours, and recrystallized to obtain p-phenylenediamine-2,4-dihydroxybenzaldehyde Schiff base; the molar ratio of p-phenylenediamine and 2,4-dihydroxybenzaldehyde is 1:2; (2) 30 parts of isophorone diisocyanate and 18 parts of polyethylene glycol are added to 100 parts of acetone and mixed, 0.8 parts of dibutyltin dilaurate are added and heated at 80°C for 1.5 hours, 10 parts of p-phenylenediamine-2,4-dihydroxybenzaldehyde Schiff base and 4 parts of hydroxyethyl acrylate are added and the reaction continues for 3 hours to obtain modified polyurethane acrylate; Mix 75 parts aliphatic polyurethane acrylate, 18 parts reactive diluent and 0.7 parts defoamer, heat to 50°C, stir for 1 hour, add 25 parts modified polyurethane acrylate, 4 parts photoinitiator and 1 part antioxidant (antioxidant 1010) and mix evenly, filter to obtain UV-curable adhesive. The reactive diluents include siloxane ethylene glycol epoxy acrylate and trimethylolpropane triacrylate in a mass ratio of 3:1; the photoinitiators include methyl benzoylformate and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide in a mass ratio of 2:1.
[0023] Comparative Example 1 is based on Example 3, but introduces only trimethylolpropane triacrylate; the remaining operation steps are the same. Pre-preparation: The preparation method of modified polyurethane acrylate is as follows: (1) p-phenylenediamine and 2,4-dihydroxybenzaldehyde are added to ethanol and mixed, refluxed for 6 hours, and recrystallized to obtain p-phenylenediamine-2,4-dihydroxybenzaldehyde Schiff base; the molar ratio of p-phenylenediamine and 2,4-dihydroxybenzaldehyde is 1:2; (2) 30 parts of isophorone diisocyanate and 18 parts of polyethylene glycol are added to 100 parts of acetone and mixed, 0.8 parts of dibutyltin dilaurate are added and heated at 80°C for 1.5 hours, 10 parts of p-phenylenediamine-2,4-dihydroxybenzaldehyde Schiff base and 4 parts of hydroxyethyl acrylate are added and the reaction continues for 3 hours to obtain modified polyurethane acrylate; Mix 75 parts aliphatic polyurethane acrylate, 18 parts trimethylolpropane triacrylate and 0.7 parts defoamer, heat to 50°C, stir for 1 hour, add 25 parts modified polyurethane acrylate, 4 parts photoinitiator and 1 part antioxidant (antioxidant 1010) and mix evenly, filter to obtain UV-curable adhesive. The photoinitiator includes methyl benzoate and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide in a mass ratio of 2:1.
[0024] Comparative Example 2 is based on Example 3, but without introducing p-phenylenediamine-2,4-dihydroxybenzaldehyde Schiff base into the modified polyurethane acrylate; the remaining operating steps are the same. Pre-preparation: The preparation method of siloxane ethylene glycol epoxy acrylate is as follows: (1) Mix 12 parts of ethylene glycol diglycidyl ether and 0.6 parts of tetrabutylammonium bromide, heat to 90°C, add 8 parts of 3-butenoic acid and 0.1 parts of polymerization inhibitor (p-hydroxyanisole), and continue stirring for 3 hours to obtain ethylene glycol epoxy acrylate; (2) Add 10 parts of ethylene glycol epoxy acrylate and 0.08 parts of Karstedt catalyst to 50 parts of isopropanol and mix, heat to 75°C, add 5 parts of tetramethyldisiloxane and stir for 4 hours to obtain siloxane ethylene glycol epoxy acrylate; The modified polyurethane acrylate is prepared by mixing 30 parts of isophorone diisocyanate and 18 parts of polyethylene glycol with 100 parts of acetone, adding 0.8 parts of dibutyltin dilaurate and heating at 80°C for 1.5 hours, then adding 4 parts of hydroxyethyl acrylate and continuing the reaction for 3 hours to obtain the modified polyurethane acrylate. Mix 75 parts aliphatic polyurethane acrylate, 18 parts reactive diluent and 0.7 parts defoamer, heat to 50°C, stir for 1 hour, add 25 parts modified polyurethane acrylate, 4 parts photoinitiator and 1 part antioxidant (antioxidant 1010) and mix evenly, filter to obtain UV-curable adhesive. The reactive diluents include siloxane ethylene glycol epoxy acrylate and trimethylolpropane triacrylate in a mass ratio of 3:1; the photoinitiators include methyl benzoylformate and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide in a mass ratio of 2:1.
[0025] Comparative Example 3 is based on Example 3, but the mass ratio of siloxane ethylene glycol epoxy acrylate to trimethylolpropane triacrylate is increased to 1:3; the remaining operating steps are the same. Pre-preparation: The preparation method of siloxane ethylene glycol epoxy acrylate is as follows: (1) Mix 12 parts of ethylene glycol diglycidyl ether and 0.6 parts of tetrabutylammonium bromide, heat to 90°C, add 8 parts of 3-butenoic acid and 0.1 parts of polymerization inhibitor (p-hydroxyanisole), and continue stirring for 3 hours to obtain ethylene glycol epoxy acrylate; (2) Add 10 parts of ethylene glycol epoxy acrylate and 0.08 parts of Karstedt catalyst to 50 parts of isopropanol and mix, heat to 75°C, add 5 parts of tetramethyldisiloxane and stir for 4 hours to obtain siloxane ethylene glycol epoxy acrylate; The preparation method of modified polyurethane acrylate is as follows: (1) p-phenylenediamine and 2,4-dihydroxybenzaldehyde are added to ethanol and mixed, refluxed for 6 hours, and recrystallized to obtain p-phenylenediamine-2,4-dihydroxybenzaldehyde Schiff base; the molar ratio of p-phenylenediamine and 2,4-dihydroxybenzaldehyde is 1:2; (2) 30 parts of isophorone diisocyanate and 18 parts of polyethylene glycol are added to 100 parts of acetone and mixed, 0.8 parts of dibutyltin dilaurate are added and heated at 80°C for 1.5 hours, 10 parts of p-phenylenediamine-2,4-dihydroxybenzaldehyde Schiff base and 4 parts of hydroxyethyl acrylate are added and the reaction continues for 3 hours to obtain modified polyurethane acrylate; Mix 75 parts aliphatic polyurethane acrylate, 18 parts reactive diluent and 0.7 parts defoamer, heat to 50°C, stir for 1 hour, add 25 parts modified polyurethane acrylate, 4 parts photoinitiator and 1 part antioxidant (antioxidant 1010) and mix evenly, filter to obtain UV-curable adhesive. The reactive diluents include siloxane ethylene glycol epoxy acrylate and trimethylolpropane triacrylate in a mass ratio of 1:3; the photoinitiators include methyl benzoylformate and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide in a mass ratio of 2:1.
[0026] Comparative Example 4 is based on Example 3, but without the addition of modified polyurethane acrylate; Pre-preparation: The preparation method of siloxane ethylene glycol epoxy acrylate is as follows: (1) Mix 12 parts of ethylene glycol diglycidyl ether and 0.6 parts of tetrabutylammonium bromide, heat to 90°C, add 8 parts of 3-butenoic acid and 0.1 parts of polymerization inhibitor (p-hydroxyanisole), and continue stirring for 3 hours to obtain ethylene glycol epoxy acrylate; (2) Add 10 parts of ethylene glycol epoxy acrylate and 0.08 parts of Karstedt catalyst to 50 parts of isopropanol and mix, heat to 75°C, add 5 parts of tetramethyldisiloxane and stir for 4 hours to obtain siloxane ethylene glycol epoxy acrylate; Mix 75 parts aliphatic polyurethane acrylate, 18 parts reactive diluent and 0.7 parts defoamer, heat to 50°C, stir for 1 hour, add 4 parts photoinitiator and 1 part antioxidant (antioxidant 1010) and mix evenly, filter to obtain UV-curable adhesive. The reactive diluents include siloxane ethylene glycol epoxy acrylate and trimethylolpropane triacrylate in a mass ratio of 3:1; the photoinitiators include methyl benzoylformate and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide in a mass ratio of 2:1.
[0027] Test 1: The UV-curable adhesives prepared in Examples 1-3 and Comparative Examples 1-4 were coated onto FPC substrates, cured into films under UV irradiation, and their shrinkage rate (%) was measured by performance analysis. The UV-curable adhesives prepared in Examples 1-3 and Comparative Examples 1-4 were cured using a DTG-60 thermogravimetric analyzer, and their thermal stability was analyzed. The adhesives were heated in a nitrogen atmosphere at a heating rate of 20 °C / min. The thermal degradation temperature (°C) when the mass loss was 5% was recorded.
[0028] Table 1 Conclusions: Comparative Example 1, based on Example 3, introduced only trimethylolpropane triacrylate; the high-functionality trimethylolpropane triacrylate alone resulted in excessively high crosslinking density and increased shrinkage, while the absence of siloxane ethylene glycol epoxy acrylate led to poor thermal stability; Comparative Example 2, based on Example 3, did not introduce p-phenylenediamine-2,4-dihydroxybenzaldehyde Schiff base into the modified polyurethane acrylate; the absence of the Schiff base structure resulted in decreased thermal stability and increased shrinkage of the UV-cured adhesive; Comparative Example 3, based on Example 3, increased the mass ratio of siloxane ethylene glycol epoxy acrylate to trimethylolpropane triacrylate to 1:3; this diluted the flexibility and thermal stability of the siloxane ethylene glycol epoxy acrylate, leading to increased crosslinking density, increased shrinkage, and decreased thermal stability; Comparative Example 4, based on Example 3, did not add modified polyurethane acrylate; the modified polyurethane acrylate has a certain rigidity, and the absence of modified polyurethane acrylate in Comparative Example 4 resulted in increased shrinkage and decreased thermal stability.
[0029] Test Experiment 2: Test Example 3 at 30mW / cm 2 The curing time under UV lamp irradiation (distance 50mm) was measured. Conclusion: The curing time of Example 3 was 15 seconds. In summary, Example 3 has good high temperature resistance, curing shrinkage rate, and curing time.
[0030] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.
Claims
1. A UV-curable adhesive for FPC, characterized in that: The UV-curable adhesive comprises the following components by weight: 60-75 parts aliphatic polyurethane acrylate, 20-25 parts modified polyurethane acrylate, 12-18 parts reactive diluent, 3-6 parts photoinitiator, 1-2 parts antioxidant, and 0.5-2 parts defoamer.
2. The UV-curable adhesive for FPC according to claim 1, characterized in that: The reactive diluent comprises siloxane ethylene glycol epoxy acrylate and trimethylolpropane triacrylate in a mass ratio of (3~5):
1.
3. The UV-curable adhesive for FPC according to claim 2, characterized in that: The preparation method of the siloxane ethylene glycol epoxy acrylate is as follows: (1) Ethylene glycol diglycidyl ether and tetrabutylammonium bromide are mixed, heated to 80~90℃, 3-butenoic acid and polymerization inhibitor are added, and stirring is continued for 2~3 hours to obtain ethylene glycol epoxy acrylate; (2) Ethylene glycol epoxy acrylate and Karstedt catalyst are added to isopropanol and mixed, heated to 65~75℃, tetramethyldisiloxane is added and stirred for 2~4 hours to obtain siloxane ethylene glycol epoxy acrylate.
4. The UV-curable adhesive for FPC according to claim 3, characterized in that: The raw materials for the ethylene glycol epoxy acrylate include the following components: by mass, 10-15 parts ethylene glycol diglycidyl ether, 0.5-1 parts tetrabutylammonium bromide, 7-8 parts 3-butenoic acid, and 0.1-0.2 parts polymerization inhibitor; the raw materials for the siloxane ethylene glycol epoxy acrylate include the following components: by mass, 8-10 parts ethylene glycol epoxy acrylate, 0.07-0.12 parts Karstedt catalyst, and 3-5 parts tetramethyldisiloxane.
5. The UV-curable adhesive for FPC according to claim 1, characterized in that: The modified polyurethane acrylate is prepared by: (1) p-phenylenediamine and 2,4-dihydroxybenzaldehyde are added to ethanol and mixed, refluxed for 6-8 hours, and recrystallized to obtain p-phenylenediamine-2,4-dihydroxybenzaldehyde Schiff base; (2) isophorone diisocyanate and polyethylene glycol are added to acetone and mixed, dibutyltin dilaurate is added and heated to react, p-phenylenediamine-2,4-dihydroxybenzaldehyde Schiff base and hydroxyethyl acrylate are added to continue the reaction to obtain modified polyurethane acrylate.
6. The UV-curable adhesive for FPC according to claim 5, characterized in that: The molar ratio of p-phenylenediamine to 2,4-dihydroxybenzaldehyde is 1:2; the raw materials of the modified polyurethane acrylate include the following components by mass: 25-30 parts isophorone diisocyanate, 13-18 parts polyethylene glycol, 0.5-1.2 parts dibutyltin dilaurate, 8-12 parts p-phenylenediamine-2,4-dihydroxybenzaldehyde Schiff base, and 3-6 parts hydroxyethyl acrylate.
7. The UV-curable adhesive for FPC according to claim 1, characterized in that: The photoinitiator comprises methyl benzoate and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide in a mass ratio of (2~3):(1~2).
8. A method for preparing a UV-curable adhesive for FPC according to any one of claims 1 to 7, characterized in that: The process includes the following steps: mixing aliphatic polyurethane acrylate, reactive diluent and defoamer, heating to 50~60℃, stirring for 1~2 hours, adding modified polyurethane acrylate, photoinitiator and antioxidant and mixing evenly, filtering to obtain UV-curable adhesive.
9. A method for preparing a UV-curable adhesive for FPC according to claim 8, characterized in that: The curing conditions for the UV-curable adhesive are: 30~60mW / cm². 2 Irradiate with UV lamps at a distance of 50~70mm.