Photocuring polycaprolactone modified blocked isocyanate as well as preparation method and application thereof

Abstract

The invention relates to the technical field of blocked isocyanate, in particular to photocuring polycaprolactone modified blocked isocyanate and a preparation method and application thereof.The photocuring polycaprolactone modified blocked isocyanate is at least prepared from polycaprolactone polyol, a catalyst, 1, 6-hexanediol diacrylate, an isocyanate polymer, hydroxyl acrylate, a polymerization inhibitor and a sealing agent; the FPC character ink prepared from the photocuring polycaprolactone modified blocked isocyanate has excellent photocuring speed, hardness, adhesive force, bending resistance and high-temperature yellowing resistance, and meets actual application requirements.

Description

Technical Field

[0001] The invention relates to the technical field of blocked isocyanate, in particular to photocurable polycaprolactone modified blocked isocyanate and a preparation method and application thereof. Background Art

[0002] The replacement of traditional screen printing technology with inkjet printing technology can greatly simplify the production process of printed circuit boards (PCBs), eliminate many PCB production facilities and expensive equipment, and is more economical than traditional screen printing in terms of cost and production efficiency, greatly shortening the production cycle and reducing costs. At present, the PCB character printing inks on the market are mainly for hard boards, such as a polyurethane modified epoxy acrylate resin and its preparation method and application disclosed in a Chinese patent (publication number CN118184951A), which mainly solves the problems of poor adhesion and yellowing of existing PCB inkjet character inks at high temperatures by optimizing the polyurethane modified epoxy acrylate resin system, but it is not well suitable for flexible circuit boards (FPCs). There are not many FPC character inks available on the market, and most of them have performance defects such as poor adhesion and poor bending resistance. It is urgent to develop a printing character ink with excellent light curing speed, adhesion, and bending resistance for application on FPC. Summary of the invention

[0003] In order to solve the above problems, the present invention provides a photocurable polycaprolactone modified blocked isocyanate. The FPC character ink prepared by the photocurable polycaprolactone modified blocked isocyanate has excellent photocuring speed, hardness, adhesion, bending resistance and high temperature yellowing resistance, meeting the actual application requirements.

[0004] On one hand, the present invention provides a photocurable polycaprolactone modified blocked isocyanate, the preparation raw materials of which include at least the following components: polycaprolactone polyol, catalyst, 1.6-hexanediol diacrylate, isocyanate polymer, hydroxy acrylate, inhibitor and blocking agent.

[0005] As a preferred technical solution, the molar ratio of -NCO in the isocyanate polymer to the hydroxyl group in the polycaprolactone polyol is (0.2-0.4):1; the mass ratio of the isocyanate polymer to the catalyst is 100:(0.1-1); the mass ratio of the isocyanate polymer to 1,6-hexanediol diacrylate (HDDA) is 1:(0.5–1).

[0006] As a preferred technical solution, the isocyanate polymer is selected from at least one of TDI dimer, TDI-TMP adduct, TDI trimer, IPDI trimer, HDI dimer, HDI biuret, HDI trimer, and H6XDI trimer; preferably, the isocyanate polymer is selected from one of IPDI trimer, HDI dimer, HDI biuret, HDI trimer, and H6XDI trimer, and is further preferably IPDI trimer or HDI trimer.

[0007] As a preferred technical solution, the weight average molecular weight of the polycaprolactone polyol is 400-4000, preferably at least one of PCL400, PCL530, PCL830, PCL2000, PCL3000, PCL4000 (the numbers represent the weight average molecular weight of the polycaprolactone polyol).

[0008] As a preferred technical solution, the catalyst is an organic tin catalyst, preferably dibutyltin dilaurate (DBTDL).

[0009] As a preferred technical solution, the molar ratio of -NCO in the isocyanate polymer to the hydroxyl group in the hydroxy acrylate is 1:(0.3-0.5); the mass ratio of the isocyanate polymer to the inhibitor is 100:(0.1-1);

[0010] As a preferred technical solution, the hydroxyacrylate is selected from at least one of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, and pentaerythritol triacrylate, preferably one of hydroxyethyl acrylate, hydroxypropyl acrylate, and hydroxybutyl acrylate.

[0011] As a preferred technical solution, the polymerization inhibitor is selected from at least one of p-methoxyphenol, hydroquinone, 2,5-dimethylhydroquinone, 2,6-di-tert-butyl-p-cresol, and 2,2,6,6-tetramethylpiperidine-nitroxide free radical.

[0012] As a preferred technical solution, the molar ratio of -NCO in the isocyanate polymer to the active hydrogen atoms in the blocking agent is 1:(0.3-0.5);

[0013] As a preferred technical solution, the blocking agent is selected from at least one of phenol, methanol, ethanol, isononylphenol, caprolactam, diisopropylamine, cyclopentanone-2-carboxymethyl ester, methyl ethyl ketone oxime, 3.5-lutidine, diethyl malonate, acetylacetone, and ethyl acetoacetate.

[0014] Preferably, the blocking agent is selected from at least one of methyl ethyl ketone oxime, 3.5-lutidine, diethyl malonate, acetylacetone, and ethyl acetoacetate, and more preferably methyl ethyl ketone oxime or ethyl acetoacetate.

[0015] Another aspect of the present invention provides a method for preparing a photocurable polycaprolactone modified blocked isocyanate, comprising at least the following steps:

[0016] (1) adding polycaprolactone polyol and a catalyst to 1,6-hexanediol diacrylate (HDDA) in sequence, and then adding isocyanate polymer in batches, maintaining the temperature at 50° C. to 85° C. for reaction, detecting the change of the -NCO group content of the system, and stopping the reaction when the theoretical value A is reached to obtain a semi-adduct 1 of polycaprolactone polyol and isocyanate polymer;

[0017] (2) adding hydroxy acrylate and polymerization inhibitor to semi-adduct 1, maintaining an excess of -NCO groups, maintaining a temperature of 50°C-85°C for reaction, detecting the change in the -NCO group content of the system, and obtaining semi-adduct 2 when the -NCO group content reaches the theoretical value B;

[0018] (3) Add the blocking agent to the semi-adduct 2, maintain the temperature at 50°C-85°C for reaction, and monitor the -NCO group content in the 1.6-hexanediol diacrylate until it is 0, thereby obtaining a light-curable polycaprolactone modified blocked isocyanate.

[0019] As a preferred technical solution, the theoretical value A in step (1) is 19.0-75.6.

[0020] As a preferred technical solution, the theoretical value B in step (2) is 6.0-24.0.

[0021] The -NCO group content in the present invention is determined by titration with di-n-butylamine:

[0022] The principle is: -NCO group reacts with excess di-n-butylamine to form urea, and the excess di-n-butylamine is then titrated with hydrochloric acid using bromocresol green as an indicator, thereby calculating the amount of di-n-butylamine consumed by the -NCO group, and then calculating the percentage of -NCO groups in the test object. Specifically: the di-n-butylamine back titration method is used to determine the -NCO group content in the system, and isocyanate reacts quantitatively with di-n-butylamine to form urea: R-NCO+(C4H9)2NH→RHCON(C4H9)2; the excess di-n-butylamine is titrated with a standard hydrochloric acid titration solution, and hydrochloric acid reacts with excess di-n-butylamine: (C4H9)2NH+HCl→(C4H9)2NH·HCl. The calculation formula for determining the -NCO group content by di-n-butylamine titration standard is: NCO%=((V1-V2)NM) / G×100%,

[0023] Where, V1 is the milliliters of hydrochloric acid standard solution used in the blank test;

[0024] V2 is the milliliters of hydrochloric acid standard solution used in the titration test;

[0025] N is the molar concentration of standard hydrochloric acid solution, mol / L;

[0026] M is the number of grams per milliequivalent of isocyanate, 0.042;

[0027] G is the mass of the sample, g.

[0028] -NCO theoretical content calculation:

[0029] Remaining NCO moles × 36.5 (molecular weight of hydrochloric acid) * 1000 / total mass of the system.

[0030] The photocurable polycaprolactone modified blocked isocyanate provided by the present invention is designed to first prepare an adduct of polycaprolactone polyol and isocyanate polymer, keeping the -NCO group in excess; then react with hydroxy acrylate, keeping the -NCO group in excess; the remaining -NCO groups are reacted with a blocking agent to prepare the photocurable polycaprolactone modified blocked isocyanate, thereby ensuring the comprehensive performance of the FPC character ink prepared subsequently. Further optimization is made by selecting and proportioning various raw materials in the system, especially by using IPDI trimer or HDI trimer, the -NCO group in the IPDI trimer or HDI trimer is successively reacted with polycaprolactone polyol and hydroxy acrylate and then sealed with methyl ethyl ketone oxime or ethyl acetoacetate. When a single-component ink is configured, the stability of the formula can be maintained during long-term storage, and the stability of the ink itself can be maintained when the inkjet is heated to 50°C for printing. The unsealing temperature range is 110-140°C. When heated and cured at 150°C×60min, it can be unsealed again and cross-linked and cured with other components in the formula, such as solid bisphenol A epoxy or hydroxy acrylate monomer, to improve the adhesion of the characters on the FPC board.

[0031] The third aspect of the present invention provides an application of a photocurable polycaprolactone modified blocked isocyanate for use in the preparation of FPC inkjet character inks.

[0032] As a preferred technical solution, the FPC inkjet character ink, measured by weight, has raw materials for its preparation that include at least the following components: 20-30 parts of photocurable polycaprolactone modified blocked isocyanate, 5-10 parts of photoinitiator, 5-10 parts of bisphenol A epoxy resin, 30-80 parts of acrylate monomer, 20-30 parts of color paste, and 0.5-2 parts of leveling agent.

[0033] As a preferred technical solution, the epoxy equivalent of the bisphenol A epoxy resin is 450-3000 g / eq, preferably 450-1000 g / eq.

[0034] As a preferred technical solution, the photoinitiator is selected from 2-hydroxy-2-methyl-1-phenylpropanone-1, 2-methyl-1-(4-methylmercaptophenyl)-2-morpholinopropanone-1, 2-phenyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,4,6-trimethyl At least one of 2-(3-benzoylphenyl)guanidine propionate, 1-(anthraquinone-2-yl)ethylimidazole carboxylate, tetraethyl Michler's ketone and methyl o-benzoylbenzoate. Preferably, the photoinitiator is a combination of photoinitiator TPO and photoinitiator 819, and the mass ratio of the photoinitiator TPO to the photoinitiator 819 is (2-5): (1-3).

[0035] As a preferred technical solution, the acrylic acid ester monomer includes at least hydroxy acrylate, and the hydroxy acrylate is selected from at least one of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, caprolactone-modified hydroxyethyl acrylate, and pentaerythritol triacrylate. Preferably, the hydroxy acrylate is a combination of hydroxybutyl acrylate and caprolactone-modified hydroxyethyl acrylate, and the mass ratio of the hydroxybutyl acrylate to the caprolactone-modified hydroxyethyl acrylate is (1-1.5):1.

[0036] As a preferred technical solution, the acrylate monomer also includes diphenylethyl acrylate, ethoxylated phenoxy acrylate, o-phenylphenoxy acrylate, 2-(p-isopropylphenyl-phenoxy)-ethyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, ethoxyethoxyethyl acrylate, glycidyl methacrylate, isobornyl acrylate, isobornyl methacrylate, tetrahydrofurfuryl acrylate, lauric acid acrylate, lauric acid methacrylate, cyclotrimethylolpropane formal acrylate, dipropylene glycol diacrylate, tripropylene glycol acrylate, neopentyl glycol acrylate, propoxylated neopentyl glycol acrylate, 1.6-hexanediol diacrylate, tricyclohexanedimethanol diacrylate, tri(2-hydroxyethyl)isocyanuric acid triacrylate, trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, and at least one of dipentaerythritol hexaacrylate.

[0037] Preferably, the acrylate monomer further includes 1.6-hexanediol diacrylate and ethoxylated trimethylolpropane triacrylate.

[0038] Preferably, the mass ratio of the hydroxy acrylate, 1.6-hexanediol diacrylate and ethoxylated trimethylolpropane triacrylate is (10-25):(10-20):(3-8).

[0039] As a preferred technical solution, the leveling agent is at least one of a polyacrylate leveling agent and a silicone leveling agent, preferably a silicone leveling agent BYK-333.

[0040] The color paste is a titanium dioxide nano-color paste, and the preparation method of the titanium dioxide nano-color paste is: 30-60 parts of HDDA, 40-60 parts of titanium dioxide, and 2-6 parts of dispersant DISPERBYK-111 are dispersed in a high-speed disperser at 1500-2000 rpm for 3-5 hours, and then ground with a sand mill (equipment model NMM-1L, Boyi Industrial Technology) to obtain a titanium dioxide nano-color paste with a Dm (average particle size) ≤300nm (detected by a NICOMP N3000 particle size tester).

[0041] The preparation method of the FPC inkjet character ink is as follows: dispersing photocurable polycaprolactone modified blocked isocyanate, photoinitiator, bisphenol A epoxy resin, acrylate monomer, color paste and leveling agent by a high-speed disperser at 500-800 rpm for 2-4 hours, adjusting the viscosity to ≤14 cP (45° C.) (Brown DVN rotational viscometer) by HDDA, and filtering through 0.45 um and 0.22 um filter elements in turn to obtain PCB character printing ink.

[0042] The FPC inkjet character ink provided by the present invention, by introducing photocurable polycaprolactone modified blocked isocyanate and coordinating with other raw materials in the system, makes the provided product have excellent photocuring speed, adhesion and bending resistance. In the FPC manufacturing process, the characters will not fall off or crack, and can be used for character identification in FPC to obtain high-quality products.

[0043] Beneficial Effects

[0044] 1. The present invention provides a photocurable polycaprolactone modified blocked isocyanate. The FPC character ink prepared by using the photocurable polycaprolactone modified blocked isocyanate has excellent photocuring speed, hardness, adhesion, bending resistance and high temperature yellowing resistance, meeting the actual application requirements.

[0045] 2. The photocurable polycaprolactone modified blocked isocyanate provided by the present invention is designed to first prepare an adduct of polycaprolactone polyol and isocyanate polymer, keeping the -NCO group in excess; then react with hydroxy acrylate, keeping the -NCO group in excess; the remaining -NCO groups are then reacted with a blocking agent to prepare a photocurable polycaprolactone modified blocked isocyanate, thereby ensuring the comprehensive performance of the FPC character ink prepared subsequently.

[0046] 3. The present invention further optimizes the selection and ratio of each raw material in the compounding system, especially adopts IPDI trimer or HDI trimer. The -NCO group in the IPDI trimer or HDI trimer is successively reacted with polycaprolactone polyol and hydroxy acrylate and then sealed with methyl ethyl ketone oxime or ethyl acetoacetate. When a single-component ink is configured, the stability of the formula can be maintained during long-term storage, and the stability of the ink itself can be maintained when the inkjet is heated to 50°C for printing. The unsealing temperature range is 110-140°C. When heated and cured at 150°C×60min, it can be unsealed again, and cross-linked and cured with other components in the formula, such as solid bisphenol A epoxy or hydroxy acrylate monomer, to improve the adhesion of the characters on the FPC board.

[0047] 4. The FPC inkjet character ink provided by the present invention, by introducing photocurable polycaprolactone modified blocked isocyanate and coordinating with other raw materials in the system, makes the provided product have excellent photocuring speed, adhesion and bending resistance. In the FPC manufacturing process, the characters will not fall off or crack. It can be used for character identification in FPC to obtain high-quality products.

[0048] 5. The FPC inkjet character ink provided by the present invention has excellent hardness, adhesion, bending resistance and high temperature yellowing resistance at a relatively low viscosity, is easy to operate, and greatly improves the FPC process efficiency. DETAILED DESCRIPTION

[0049] Example 1

[0050] Embodiment 1 of the present invention provides a photocurable polycaprolactone modified blocked isocyanate, and the preparation method thereof is as follows:

[0051] (1) 10.5 g of polycaprolactone diol PCL400 (Guangzhou Haoyi New Materials Technology Co., Ltd.) and 0.25 g of dibutyltin dilaurate (DBTDL) were added to 50.4 g of 1.6 hexanediol diacrylate (HDDA), and three equal batches of HDI trimer (model N3300, from Bayer, Germany) totaling 50.5 g were added. The reaction temperature was maintained at 60°C, and the change in the -NCO group content in the reaction system was detected. When the -NCO group content reached the theoretical value of 75.6, semi-adduct 1 was obtained.

[0052] (2) 15.2 g of hydroxyethyl acrylate was added to the semi-adduct 1, the reaction temperature was maintained at 60° C., and the change in the -NCO group content in the reaction system was detected. When the -NCO group content reached the theoretical value of 24.0, the semi-adduct 2 was obtained.

[0053] (3) Add 6.9 g of methyl ethyl ketone oxime to the semi-adduct 2, maintain the reaction temperature at 60° C., and detect the change in the -NCO group content in the reaction system. When the -NCO group content is 0, a photocurable polycaprolactone modified blocked isocyanate is obtained.

[0054] Example 2

[0055] Embodiment 2 of the present invention provides a photocurable polycaprolactone modified blocked isocyanate, and the preparation method thereof is as follows:

[0056] (1) 32.6 g of polycaprolactone diol PCL830 (Guangzhou Haoyi New Materials Technology Co., Ltd.) and 0.25 g of dibutyltin dilaurate (DBTDL) were added to 50.4 g of 1.6 hexanediol diacrylate (HDDA), and three equal batches of HDI trimer (model N3300, from Bayer, Germany) totaling 50.5 g were added. The reaction temperature was maintained at 70°C, and the change in the -NCO group content in the reaction system was detected. When the -NCO group content reached the theoretical value of 41.5, semi-adduct 1 was obtained.

[0057] (2) 13.6 g of hydroxypropyl acrylate was added to the semi-adduct 1, the reaction temperature was maintained at 70° C., and the change in the -NCO group content in the reaction system was detected. When the -NCO group content reached the theoretical value of 19.3, the semi-adduct 2 was obtained.

[0058] (3) 9.1 g of methyl ethyl ketone oxime was added to the semi-adduct 2, the reaction temperature was maintained at 70° C., and the change in the -NCO group content in the reaction system was detected. When the -NCO group content was 0, a photocurable polycaprolactone modified blocked isocyanate was obtained.

[0059] Example 3

[0060] Embodiment 3 of the present invention provides a photocurable polycaprolactone modified blocked isocyanate, and the preparation method thereof is as follows:

[0061] (1) 80 g of polycaprolactone diol PCL2000 (Guangzhou Haoyi New Materials Technology Co., Ltd.) and 0.3 g of dibutyltin dilaurate (DBTDL) were added to 50 g of 1.6 hexanediol diacrylate (HDDA), and three equal batches of IPDI trimer (100 g in total) (solid content 70%, solvent PM, model Z4470BA, from Bayer, Germany) were added, the reaction temperature was maintained at 80°C, and the change in the -NCO group content in the reaction system was detected. When the -NCO group content reached the theoretical value of 19.0, semi-adduct 1 was obtained.

[0062] (2) 11.5 g of hydroxybutyl acrylate was added to the semi-adduct 1, the reaction temperature was maintained at 80° C., and the change in the -NCO group content in the reaction system was detected. When the -NCO group content reached the theoretical value of 6.0, the semi-adduct 2 was obtained.

[0063] (3) 5.2 g of ethyl acetoacetate was added to the semi-adduct 2, the reaction temperature was maintained at 80° C., and the change in the -NCO group content in the reaction system was detected. When the -NCO group content was 0, a photocurable polycaprolactone-modified blocked isocyanate was obtained.

[0064] Comparative Example 1

[0065] Comparative Example 1 of the present invention provides a polyester diol-modified light-curable polyurethane acrylate, and the preparation method thereof is as follows:

[0066] (1) 26.2 g of polyester diol PCL400 (Guangzhou Haoyi New Materials Technology Co., Ltd.) and 0.25 g of dibutyltin dilaurate (DBTDL) were added to 50.4 g of 1,6-hexanediol diacrylate (HDDA), and three equal batches of HDI trimer (model N3300, from Bayer, Germany) totaling 50.5 g were added. The reaction temperature was maintained at 60° C. The change in the -NCO group content in the reaction system was detected. When the -NCO group content reached 50% of the initial content, semi-adduct 1 was obtained.

[0067] (2) Add 15.2 g of hydroxyethyl acrylate to the semi-adduct 1, maintain the reaction temperature at 60° C., and detect the change in the -NCO group content in the reaction system. When the -NCO group content is 0, a polyester diol-modified photocurable polyurethane acrylate 1 is obtained.

[0068] Comparative Example 2

[0069] Comparative Example 2 of the present invention provides a blocked isocyanate, and its preparation method is as follows:

[0070] 50.5 g HDI trimer (model N3300, from Bayer, Germany) and 0.25 g dibutyltin dilaurate (DBTDL) were added to 50.4 g 1.6 hexanediol diacrylate (HDDA), and 22.8 g methyl ethyl ketone oxime was added to the semi-adduct 1. The reaction temperature was maintained at 70°C, and the change in the -NCO group content in the reaction system was detected. When the -NCO group content was 0, a blocked isocyanate 2 was obtained.

[0071] Comparative Example 3

[0072] Comparative Example 2 of the present invention provides a photocurable blocked isocyanate, and the preparation method thereof is as follows:

[0073] (1) 50.5 g of HDI trimer (model N3300, from Bayer, Germany) and 0.25 g of dibutyltin dilaurate (DBTDL) were added to 50.4 g of 1.6 hexanediol diacrylate (HDDA), and 15.2 g of hydroxyethyl acrylate was added. The reaction temperature was maintained at 70° C. The change in the -NCO group content in the reaction system was detected. When the -NCO group content reached 50% of the initial NCO content, semi-adduct 1 was obtained.

[0074] (2) 11.4 g of methyl ethyl ketone oxime was added to the semi-adduct 1, the reaction temperature was maintained at 70° C., and the change in the -NCO group content in the reaction system was detected. When the -NCO group content was 0, a photocurable blocked isocyanate 3 was obtained.

[0075] Application Examples 1-3, Application Comparative Examples 1-3

[0076] Application Examples 1-3 and Application Comparative Examples 1-3 of the present invention provide an FPC inkjet character ink, and the formula is shown in Table 1 in parts by weight.

[0077] Table 1

[0078]

[0079] Note 1: The photocurable polycaprolactone modified blocked isocyanate prepared in Examples 1, 2 and 3 is used in Application Examples 1, 2 and 3, respectively, and the products prepared in Comparative Examples 1, 2 and 3 are used in Application Comparative Examples 1, 2 and 3, respectively.

[0080] Note 2: JRCURE-1108 (general grade TPO), Tianjin Jiuri New Materials Co., Ltd.

[0081] Note 3: JRCURE-1110 (general grade 819), Tianjin Jiuri New Materials Co., Ltd.

[0082] Note 4: The material is a mixture of solid bisphenol A epoxy resin (Nan Ya NPES-902) and HDDA in a mass ratio of 1:1.

[0083] Note 5: Titanium dioxide nano-color paste is self-made. 45 parts of HDDA, 50 parts of titanium dioxide and 5 parts of dispersant DISPERBYK-111 are dispersed in a high-speed disperser at 1500 rpm for 4 hours, and then ground with a sand mill (equipment model NMM-1L, Boyi Industrial Technology) to obtain a titanium dioxide nano-color paste with Dm (average particle size) ≤ 300nm (detected by NICOMP N3000 particle size tester).

[0084] Note 6: 4-HBA, hydroxybutyl acrylate, Osaka Organic, Japan.

[0085] Note 7: PCL-HA2, caprolactone modified hydroxyethyl acrylate, Hunan Juren.

[0086] Note 8: HDDA, 1,6-hexanediol diacrylate, Changxing Chemical.

[0087] Note 9: (EO)3TMPTA, ethoxylated trimethylolpropane triacrylate, Changxing Chemical.

[0088] Note 10: The leveling agent is BYK-333, BYK from Germany.

[0089] The preparation method of the FPC inkjet character ink is as follows: the raw materials in Table 1 are mixed by a high-speed disperser at 600 rpm for 4 hours, the viscosity is adjusted to ≤14 cP (45° C.) by HDDA (Brown DVN rotational viscometer), and filtered through 0.45 um and 0.22 um filter elements in sequence to obtain PCB character printing ink.

[0090] Performance Testing

[0091] The FPC inkjet character ink provided in the application examples 1-3 and the application comparison examples 1-3 was printed on the FPC board by a character inkjet printer (equipment model Saturn-M02P, Shenzhen Jinxin Technology, nozzle model KM1024iMHE), and the number of prints was 3PASS (each light energy was 100mJ / cm 2 , the light source is UV-LED 395nm cold light source), the final coating thickness is controlled at 12-15μm, and then after high-temperature baking at 150℃×60min, the hardness, adhesion, high-temperature yellowing resistance and bending resistance of FPC inkjet character ink are tested. The test method is as follows, and the test results are shown in Table 2.

[0092] (1) Hardness

[0093] The hardness is tested by a pencil hardness tester (1kg). If the hardness is ≥4H, it is qualified, otherwise it is unqualified.

[0094] (2) Adhesion

[0095] According to the 100-grid test method, use 3M600# tape to adhere 3 times. If there is no peeling at 100 / 100, it is qualified. If there is peeling, it is unqualified.

[0096] (3) High temperature yellowing resistance

[0097] The FPC inkjet character printing ink is sprayed on the FPC board according to the above requirements. After high-temperature curing at 150℃×60min, it is subjected to a (260±5)℃×10s×5 times floating solder test. If the characters do not turn yellow, they are qualified, otherwise they are unqualified.

[0098] (4) Bending resistance

[0099] According to JIS C 6471 test method for copper clad laminate for flexible printed circuit boards, the bending radius is 2mm, and the bending resistance laboratory is ≥600 times to pass, otherwise it is unqualified.

[0100] Table 2

[0101]

Claims

1. A photocurable polycaprolactone modified blocked isocyanate, characterized in that: The raw materials for preparing the polyol include at least the following components: polycaprolactone polyol, catalyst, 1.6-hexanediol diacrylate, isocyanate polymer, hydroxy acrylate, inhibitor and blocking agent.

2. The photocurable polycaprolactone modified blocked isocyanate according to claim 1, characterized in that: The molar ratio of -NCO in the isocyanate polymer to the hydroxyl group in the polycaprolactone polyol is (0.2-0.4):1; the mass ratio of the isocyanate polymer to the catalyst is 100:(0.1-1); and the mass ratio of the isocyanate polymer to 1.6-hexanediol diacrylate is 1:(0.5-1).

3. The photocurable polycaprolactone modified blocked isocyanate according to claim 2, characterized in that: The isocyanate polymer is selected from at least one of TDI dimer, TDI-TMP adduct, TDI trimer, IPDI trimer, HDI dimer, HDI biuret, HDI trimer and H6XDI trimer.

4. The photocurable polycaprolactone modified blocked isocyanate according to claim 3, characterized in that: The molar ratio of -NCO in the isocyanate polymer to the hydroxyl group in the hydroxy acrylate is 1:(0.3-0.5); the mass ratio of the isocyanate polymer to the inhibitor is 100:(0.1-1).

5. The photocurable polycaprolactone modified blocked isocyanate according to claim 4, characterized in that: The molar ratio of -NCO in the isocyanate polymer to the active hydrogen atoms in the blocking agent is 1:(0.3-0.5).

6. The photocurable polycaprolactone modified blocked isocyanate according to claim 5, characterized in that: The blocking agent is selected from at least one of phenol, methanol, ethanol, isononylphenol, caprolactam, diisopropylamine, cyclopentanone-2-carboxymethyl ester, methyl ethyl ketone oxime, 3.5-lutidine, diethyl malonate, acetylacetone, and ethyl acetoacetate.

7. A method for preparing the light-curable polycaprolactone modified blocked isocyanate according to any one of claims 1 to 6, characterized in that: At least the following steps are included: (1) adding polycaprolactone polyol and a catalyst to 1,6-hexanediol diacrylate in sequence, and then adding isocyanate polymer in batches, maintaining the temperature at 50° C. to 85° C. for reaction, detecting the change of the -NCO group content of the system, and stopping the reaction when the theoretical value A is reached to obtain a semi-adduct 1 of polycaprolactone polyol and isocyanate polymer; (2) adding hydroxy acrylate and polymerization inhibitor to semi-adduct 1, maintaining an excess of -NCO groups, maintaining a temperature of 50°C-85°C for reaction, detecting the change in the -NCO group content of the system, and obtaining semi-adduct 2 when the -NCO group content reaches the theoretical value B; (3) Add the blocking agent to the semi-adduct 2, maintain the temperature at 50°C-85°C for reaction, and monitor the -NCO group content in the 1.6-hexanediol diacrylate until it is 0, thereby obtaining a light-curable polycaprolactone modified blocked isocyanate.

8. The method for preparing the light-curable polycaprolactone modified blocked isocyanate according to claim 7, characterized in that: The theoretical value A in the step (1) is 19.0-75.6, and the theoretical value B in the step (2) is 6.0-24.

0.

9. An application of the photocurable polycaprolactone modified blocked isocyanate according to any one of claims 1 to 6, characterized in that: The invention is used for preparing FPC inkjet character ink; the FPC inkjet character ink comprises at least the following components in parts by weight: 20-30 parts of photocurable polycaprolactone modified blocked isocyanate, 5-10 parts of photoinitiator, 5-10 parts of bisphenol A epoxy resin, 30-80 parts of acrylate monomer, 20-30 parts of color paste and 0.5-2 parts of leveling agent.

10. The use of the photocurable polycaprolactone modified blocked isocyanate according to claim 9, characterized in that: The epoxy equivalent of the bisphenol A epoxy resin is 450-3000 g / eq.

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