A flame-retardant UV-curable adhesive, its preparation method and application

Abstract

The present invention relates to the technical field of adhesives, and specifically discloses a flame-retardant UV-curable adhesive, its preparation method and application. A flame-retardant UV-curable adhesive comprises the following raw materials in parts by weight: 40-80 parts of acrylic resin, 20-50 parts of reactive diluent, 20-30 parts of polyvinyl alcohol, 10-20 parts of mercaptopropyl isobutyl silsesquioxane, 3-10 parts of photoinitiator, 10-20 parts of P-N type flame retardant, 3-8 parts of synergist, and 0.5-2 parts of defoamer; and a multi-component flame-retardant system can be formed between the P-N type flame retardant and the synergist to improve the flame-retardant performance of the adhesive, so that its oxygen index reaches more than 35%, passes the UL-94 vertical burning test at V-0 level, realizes post-combustion expansion and smoke suppression, and there is no dripping and no obvious smoke generation during the combustion process.

Description

Technical Field

[0001] The present invention relates to the technical field of adhesives, and more specifically, it relates to a flame-retardant UV-curable adhesive and its preparation method and application. Background Art

[0002] Flame-retardant adhesives are mainly composed of a base adhesive, a flame retardant, fillers, and additives, etc. The base adhesive is one of the main components of the flame-retardant adhesive, which mixes the flame retardant, fillers, and additives together and has good bonding performance. The flame retardant is the core component of the flame-retardant adhesive, which plays a flame-retardant role during a fire; there are many types of flame retardants, but there are also certain problems in the use of different types of flame retardants. For example, although halogen-based flame retardants have high flame-retardant efficiency, the toxic gases such as hydrogen bromide released during combustion seriously endanger people's lives and health, which is not conducive to the practical application of halogen-based flame retardants; phosphorus-based flame retardants have the advantages of low toxicity and good dispersibility, but some phosphorus-based flame retardants are complex to prepare and have high costs, which is not conducive to large-scale production; nitrogen-based flame retardants have the advantages of low smoke and high stability, but their flame-retardant efficiency is not high when used alone and need to be compounded with other flame retardants; carbon-based flame retardants have the effects of anti-corrosion and smoke suppression, but some flame retardants are complex to prepare and the process is dangerous. Metal oxide flame retardants are widely sourced, have good thermal stability, and produce little smoke during combustion, but their flame-retardant efficiency is low, and a large amount of flame retardant needs to be added to achieve the flame-retardant effect, which is likely to cause deterioration of the mechanical properties of the material.

[0003] Currently, the invention patent CN118421246A discloses that the raw materials of a flame-retardant adhesive composition include epoxy resin, acrylic copolymer, ammonium polyphosphate, calcium carboxymethyl cellulose, expanded graphite, curing agent, diluent, and defoaming agent; and expanded graphite is modified with ferrocenyl ketone compound; the flame-retardant performance of the obtained adhesive still needs to be improved; therefore, the present invention provides a flame-retardant UV-curable adhesive and its preparation method and application. Summary of the Invention

[0004] In order to solve the problem of poor flame-retardant performance of existing adhesives, the present invention provides a flame-retardant UV-curable adhesive and its preparation method and application.

[0005] In the first aspect, the present invention provides a flame-retardant UV-curable adhesive, adopting the following technical solution:

[0006] A flame-retardant UV-curable adhesive, comprising the following raw materials in parts by weight: 40 - 80 parts of acrylic resin, 20 - 50 parts of reactive diluent, 20 - 30 parts of polyvinyl alcohol, 10 - 20 parts of mercaptopropyl isobutyl silsesquioxane, 3 - 10 parts of photoinitiator, 10 - 20 parts of P-N type flame retardant, 3 - 8 parts of synergist, and 0.5 - 2 parts of defoaming agent.

[0007] Preferably, the preparation method of the P-N type flame retardant comprises the following steps:

[0008] Add 1,4-bis(3-aminopropyl)piperazine to ethanol. After mixing evenly, slowly add an aqueous solution of phytic acid. After the dropping is completed within 5-10 min, react at 60-70 °C for 10-20 h. After the reaction is completed, centrifuge, wash, dry, and purify to obtain the P-N type flame retardant.

[0009] Preferably, the mass ratio of 1,4-bis(3-aminopropyl)piperazine, ethanol, and the aqueous solution of phytic acid is 6 g:40-60 g:13.2-22 g;

[0010] The content of phytic acid in the aqueous solution of phytic acid is 30-50 wt%.

[0011] Preferably, the synergist is at least one of α-zirconium phosphate, organic bentonite, and calcium metaborate.

[0012] Preferably, the synergist is obtained by mixing α-zirconium phosphate, organic bentonite, and calcium metaborate in a mass ratio of 1:5:4.

[0013] Preferably, the reactive diluent is at least one of isooctyl acrylate, dipropylene glycol diacrylate, isobornyl acrylate, tetraethylene glycol dimethacrylate, neopentyl glycol diacrylate, diethylene glycol diacrylate, glycidyl methacrylate, and dodecyl methacrylate.

[0014] Preferably, the photoinitiator is at least one of 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl phenyl acetone, (2,4,6-trimethylbenzoyl) diphenyl phosphine oxide, ethyl 2,4,6-trimethylbenzoyl phenylphosphinate, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone, and benzophenone.

[0015] Preferably, the defoamer is at least one of BYK-051, BYK-530, BYK-025, BYK-1723, BYK-1724, BYK-1611, and BYK-1617.

[0016] In a second aspect, the present invention provides a preparation method of a flame-retardant UV curable adhesive, adopting the following technical solution:

[0017] A preparation method of a flame-retardant UV curable adhesive comprises the following steps:

[0018] According to the formula, mix acrylic resin, reactive diluent and defoamer, heat up to 50 - 70 °C, stir for 1 - 2 h, then heat up to 80 - 90 °C, add polyvinyl alcohol, mercaptopropylisobutylcage silsesquioxane, P-N type flame retardant and synergist, and stir for 1 - 2 h; cool down to 50 - 75 °C, add photoinitiator, and stir for 1 - 2 h to obtain the flame-retardant UV curable adhesive.

[0019] In the third aspect, the present invention provides an application of a flame-retardant UV curable adhesive, adopting the following technical solution:

[0020] A flame-retardant UV curable adhesive is applied to pressure-sensitive tapes.

[0021] In summary, the present invention has the following beneficial effects:

[0022] 1. The raw materials of the flame-retardant UV curable adhesive of the present invention include acrylic resin, reactive diluent, polyvinyl alcohol, mercaptopropylisobutylcage silsesquioxane, photoinitiator, P-N type flame retardant, synergist, and defoamer. These raw materials interact with each other, and the obtained flame-retardant UV curable adhesive has excellent flame retardancy, good UV curing characteristics, and excellent bonding performance, and can be widely applied to pressure-sensitive tapes.

[0023] 2. The present invention utilizes the reaction between the phosphate group in phytic acid and the amino group in 1,4-bis(3-aminopropyl)piperazine, and strictly controls the mass ratio and reaction conditions of the two, so that each P-N type flame retardant molecule contains three [-NH-P=O(OH)-O-] bonds, forming a P-N type flame retardant with a unique structure.

[0024] The P-N type flame retardant of the present invention will lose the terminal amino group during heating, generating non-combustible nitrogen-containing gases. The non-combustible gases can not only increase the height of the carbon layer, play a strong barrier role for the carbon layer in the condensed phase, isolate the transfer of oxygen and heat; but also dilute the concentration of combustible gases and prevent the transfer of flame in the gas phase; in addition, the P-N type flame retardant has multiple highly active P-N bonds, and the electron-hole pairs in the P-N bonds have the ability to absorb and release energy, which will promote the formation of a continuous, dense and difficult-to-burn carbon layer from the decomposition products of the adhesive in the condensed phase, thereby isolating the transfer of oxygen and heat, and greatly improving the flame retardancy of the adhesive. In addition, the P-N type flame retardant of the present invention has a unique spatial structure, which can be better compatible with other raw materials and improve the bonding performance of the adhesive.

[0025] 3. The synergist of the present invention is at least one of zirconium α-phosphate, organic bentonite, and calcium metaborate. Zirconium α-phosphate catalyzes the cross-linking of polymers into carbon at high temperatures, forming a dense protective layer that effectively blocks the transfer of oxygen and heat, reducing the combustion rate; organic bentonite has good thickening, thixotropic and other properties, which can improve the fluidity of the material and the dispersibility of the flame retardant, thereby enhancing the flame retardant effect; calcium metaborate can lose its structural water at high temperatures, and the generated water vapor plays a role in absorbing heat and cooling and diluting oxygen in the air. At the same time, a glassy expansion layer can be formed during combustion, which can inhibit the generation of flammable gases and prevent oxidation reactions and thermal decomposition. The present invention further preferably uses a mixture of zirconium α-phosphate, organic bentonite, and calcium metaborate in a specific mass ratio as the synergist. The three jointly enhance the flame retardant effect of the adhesive through synergistic effects such as catalytic carbonization and barrier effects, heat absorption and oxygen dilution, and improvement of the dispersibility of the flame retardant.

[0026] 4. The P-N type flame retardant and the synergist of the present invention can form a multi-component flame retardant system, improving the flame retardant performance of the adhesive, making its oxygen index reach more than 35%, passing the UL-94 vertical burning test at V-0 level, achieving post-combustion expansion and smoke suppression, and having no dripping and no obvious smoke generation during the combustion process.

[0027] 5. The preparation method of the flame retardant UV curable adhesive of the present invention has simple steps and low cost. During the preparation process, various process parameters are controlled to promote the interaction between various raw materials. Under UV light, a high-performance adhesive can be obtained, which has good flame retardant effect, anti-dripping, low smoke generation, and excellent bonding performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings described herein are used to provide a further understanding of the present invention and form a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0029] Figure 1 is the nuclear magnetic resonance hydrogen spectrum of the P-N type flame retardant provided in Preparation Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0030] The following further describes the present invention in detail with reference to the embodiments.

[0031] The materials and reagents used in the present invention, unless otherwise specified, can be obtained from commercial sources; among them, mercaptopropyl isobutyl cage silsesquioxane, CAS No. 480438-85-5, was purchased from Xi'an Qiyue Biotechnology Co., Ltd.; 1,4-bis (3-aminopropyl) piperazine, CAS No. 7209-38-3, was purchased from Tesco Chemical Co., Ltd.; acrylic resin, CAS No. 94188-59-7, was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.; polyvinyl alcohol, CAS No. 9002-89-5, Mw 13000-23000, 98% hydrolysis, purchased from Shanghai MacLean Biochemical Technology Co., Ltd.; α-zirconium phosphate, CAS No. 13772-29-7, average particle size 2μm, purchased from Shanghai MacLean Biochemical Technology Co., Ltd.; organic bentonite (DK2) was purchased from Zhejiang Fenghong New Materials Co., Ltd.; calcium metaborate, CAS No. 13701-64-9, 39-44% B 2 O 3 basis, 31-37% CaO basis, purchased from Shanghai MacLean Biochemical Technology Co., Ltd.; piperazine pyrophosphate, CAS No. 66034-17-1, purchased from Zhongshan Dixin Chemical Co., Ltd.

[0032] Preparation Example 1-4 provides a method for preparing a PN type flame retardant.

[0033] Preparation Example 1:

[0034] The preparation method of PN type flame retardant comprises the following steps:

[0035] Add 6 g of 1,4-bis(3-aminopropyl)piperazine to 40 g of ethanol, mix well, then slowly add 22 g of phytic acid aqueous solution (phytic acid content is 30 wt%), add dropwise within 10 min, react at 60 ° C for 10 h, centrifuge, wash, dry, recrystallize with 100 mL of methanol / tetrahydrofuran (volume ratio is 1:3), filter and dry to obtain 9.98 g of PN flame retardant (purity 99.9%, yield 82.8%).

[0036] Preparation Example 2:

[0037] The preparation method of PN type flame retardant comprises the following steps:

[0038] Add 6 g of 1,4-bis(3-aminopropyl)piperazine to 50 g of ethanol, mix well, slowly add 16.5 g of phytic acid aqueous solution (phytic acid content is 40 wt%), add dropwise within 8 min, react at 65 ° C for 15 h, centrifuge, wash, dry, recrystallize with 100 mL of methanol / tetrahydrofuran (volume ratio of 1:3), filter and dry to obtain 10.13 g of PN flame retardant (purity 99.9%, yield 84.0%).

[0039] Preparation Example 3:

[0040] The preparation method of the P-N type flame retardant comprises the following steps:

[0041] 6 g of 1,4-bis(3-aminopropyl)piperazine was added to 60 g of ethanol. After mixing evenly, an aqueous solution of 13.2 g of phytic acid (the content of phytic acid was 50 wt%) was slowly added. After the dropping was completed within 5 min, the reaction was carried out at 70 °C for 20 h. After the reaction was completed, centrifugation, washing, and drying were carried out. Recrystallization was carried out with 100 mL of methanol / tetrahydrofuran (volume ratio 1:3), suction filtration, and drying to obtain 10.29 g of the P-N type flame retardant (purity 99.9%, yield 85.3%).

[0042] Preparation Example 4:

[0043] The P-N type flame retardant was prepared by the following method:

[0044] 1.8 g of ethylenediamine was added to 40 g of ethanol. After mixing evenly, an aqueous solution of 22 g of phytic acid (the content of phytic acid was 30 wt%) was slowly added. After the dropping was completed within 10 min, the reaction was carried out at 60 °C for 10 h. After the reaction was completed, centrifugation, washing, and drying were carried out. Recrystallization was carried out with 100 mL of acetone, suction filtration, and drying to obtain 6.78 g of the P-N type flame retardant (purity 99.9%, yield 86.3%).

[0045] Examples 1-8 provide a flame-retardant UV curable adhesive and a preparation method thereof.

[0046] Example 1:

[0047] A flame-retardant UV curable adhesive comprises the following raw materials in parts by weight: 40 parts of acrylic resin, 20 parts of reactive diluent, 20 parts of polyvinyl alcohol, 10 parts of mercaptopropyl isobutyl silsesquioxane, 3 parts of photoinitiator, 10 parts of P-N type flame retardant, 3 parts of synergist, and 0.5 part of defoamer;

[0048] Among them, the reactive diluent is isooctyl acrylate; the photoinitiator is 1-hydroxycyclohexyl phenyl ketone; the P-N type flame retardant is prepared from Preparation Example 1; the synergist is organic bentonite; the defoamer is BYK-051;

[0049] A preparation method of a flame-retardant UV curable adhesive comprises the following steps:

[0050] According to the formula, the acrylic resin, the reactive diluent, and the defoamer were mixed, heated to 50 °C, stirred for 1 h, heated to 80 °C, and polyvinyl alcohol, mercaptopropyl isobutyl silsesquioxane, the P-N type flame retardant, and the synergist were added, and stirred for 1 h; cooled to 50 °C, the photoinitiator was added, and stirred for 1 h to obtain the flame-retardant UV curable adhesive.

[0051] Example 2:

[0052] A flame-retardant UV-curable adhesive, comprising the following raw materials in parts by weight: 60 parts of acrylic resin, 35 parts of reactive diluent, 25 parts of polyvinyl alcohol, 15 parts of mercaptopropyl isobutyl silsesquioxane, 6 parts of photoinitiator, 15 parts of P-N type flame retardant, 5.5 parts of synergist, 1 part of defoamer;

[0053] Among them, the reactive diluent is obtained by mixing isobornyl acrylate and glycidyl methacrylate in a mass ratio of 1:1; the photoinitiator is ethyl 2,4,6-trimethylbenzoyl phenylphosphinate; the P-N type flame retardant is prepared from Preparation Example 2; the synergist is α-zirconium phosphate; the defoamer is BYK-1724;

[0054] A preparation method of a flame-retardant UV-curable adhesive, comprising the following steps:

[0055] According to the formula, mix the acrylic resin, reactive diluent and defoamer, heat up to 60 °C, stir for 1.5 h, heat up to 85 °C, add polyvinyl alcohol, mercaptopropyl isobutyl silsesquioxane, P-N type flame retardant and synergist, and stir for 1.5 h; cool down to 65 °C, add the photoinitiator, and stir for 1-2 h to obtain the flame-retardant UV-curable adhesive.

[0056] Example 3:

[0057] A flame-retardant UV-curable adhesive, comprising the following raw materials in parts by weight: 80 parts of acrylic resin, 50 parts of reactive diluent, 30 parts of polyvinyl alcohol, 10-20 parts of mercaptopropyl isobutyl silsesquioxane, 10 parts of photoinitiator, 20 parts of P-N type flame retardant, 8 parts of synergist, 2 parts of defoamer;

[0058] Among them, the reactive diluent is obtained by mixing isooctyl acrylate, tetraethylene glycol dimethacrylate and dodecyl methacrylate in a mass ratio of 1:1:1; the photoinitiator is 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone; the P-N type flame retardant is prepared from Preparation Example 3; the synergist is calcium metaborate; the defoamer is BYK-025;

[0059] A preparation method of a flame-retardant UV-curable adhesive, comprising the following steps:

[0060] According to the formula, mix the acrylic resin, reactive diluent and defoamer, heat up to 70 °C, stir for 2 h, heat up to 90 °C, add polyvinyl alcohol, mercaptopropyl isobutyl silsesquioxane, P-N type flame retardant and synergist, and stir for 2 h; cool down to 75 °C, add the photoinitiator, and stir for 2 h to obtain the flame-retardant UV-curable adhesive.

[0061] Example 4:

[0062] Example 4 is different from Example 1 only in that the synergist is obtained by mixing zirconium α-phosphate and organic bentonite in a mass ratio of 1:1, specifically as follows:

[0063] A flame-retardant UV-curable adhesive, comprising the following raw materials in parts by weight: 40 parts of acrylic resin, 20 parts of reactive diluent, 20 parts of polyvinyl alcohol, 10 parts of mercaptopropyl isobutyl silsesquioxane, 3 parts of photoinitiator, 10 parts of P-N type flame retardant, 3 parts of synergist, and 0.5 part of defoamer;

[0064] Among them, the reactive diluent is isooctyl acrylate; the photoinitiator is 1-hydroxycyclohexyl phenyl ketone; the P-N type flame retardant is prepared from Preparation Example 1; the synergist is obtained by mixing zirconium α-phosphate and organic bentonite in a mass ratio of 1:1; the defoamer is BYK-051;

[0065] A preparation method of a flame-retardant UV-curable adhesive, comprising the following steps:

[0066] According to the formula, mix the acrylic resin, reactive diluent and defoamer, heat up to 50 °C, stir for 1 h, heat up to 80 °C, add polyvinyl alcohol, mercaptopropyl isobutyl silsesquioxane, P-N type flame retardant and synergist, and stir for 1 h; cool down to 50 °C, add the photoinitiator, and stir for 1 h to obtain the flame-retardant UV-curable adhesive.

[0067] Example 5:

[0068] Example 5 is different from Example 1 only in that the synergist is obtained by mixing zirconium α-phosphate and calcium metaborate in a mass ratio of 1:1, specifically as follows:

[0069] A flame-retardant UV-curable adhesive, comprising the following raw materials in parts by weight: 40 parts of acrylic resin, 20 parts of reactive diluent, 20 parts of polyvinyl alcohol, 10 parts of mercaptopropyl isobutyl silsesquioxane, 3 parts of photoinitiator, 10 parts of P-N type flame retardant, 3 parts of synergist, and 0.5 part of defoamer;

[0070] Among them, the reactive diluent is isooctyl acrylate; the photoinitiator is 1-hydroxycyclohexyl phenyl ketone; the P-N type flame retardant is prepared from Preparation Example 1; the synergist is obtained by mixing zirconium α-phosphate and calcium metaborate in a mass ratio of 1:1; the defoamer is BYK-051;

[0071] A preparation method of a flame-retardant UV-curable adhesive, comprising the following steps:

[0072] According to the formula, mix acrylic resin, reactive diluent and defoamer, heat up to 50 °C, stir for 1 h, then heat up to 80 °C, add polyvinyl alcohol, mercaptopropylisobutylcage silsesquioxane, P-N type flame retardant and synergist, and stir for 1 h; cool down to 50 °C, add photoinitiator, and stir for 1 h to obtain the flame-retardant UV curable adhesive.

[0073] Example 6:

[0074] For Example 6, the difference from Example 1 is only that the synergist is obtained by mixing organobentonite and calcium metaborate with a mass ratio of 1:1, specifically as follows:

[0075] A flame-retardant UV curable adhesive, comprising the following raw materials in parts by weight: 40 parts of acrylic resin, 20 parts of reactive diluent, 20 parts of polyvinyl alcohol, 10 parts of mercaptopropylisobutylcage silsesquioxane, 3 parts of photoinitiator, 10 parts of P-N type flame retardant, 3 parts of synergist, 0.5 part of defoamer;

[0076] Among them, the reactive diluent is isooctyl acrylate; the photoinitiator is 1-hydroxycyclohexyl phenyl ketone; the P-N type flame retardant is prepared from Preparation Example 1; the synergist is obtained by mixing organobentonite and calcium metaborate with a mass ratio of 1:1; the defoamer is BYK-051;

[0077] A preparation method of a flame-retardant UV curable adhesive, comprising the following steps:

[0078] According to the formula, mix acrylic resin, reactive diluent and defoamer, heat up to 50 °C, stir for 1 h, then heat up to 80 °C, add polyvinyl alcohol, mercaptopropylisobutylcage silsesquioxane, P-N type flame retardant and synergist, and stir for 1 h; cool down to 50 °C, add photoinitiator, and stir for 1 h to obtain the flame-retardant UV curable adhesive.

[0079] Example 7:

[0080] For Example 7, the difference from Example 1 is only that the synergist is obtained by mixing α-zirconium phosphate, organobentonite and calcium metaborate with a mass ratio of 1:1:1, specifically as follows:

[0081] A flame-retardant UV curable adhesive, comprising the following raw materials in parts by weight: 40 parts of acrylic resin, 20 parts of reactive diluent, 20 parts of polyvinyl alcohol, 10 parts of mercaptopropylisobutylcage silsesquioxane, 3 parts of photoinitiator, 10 parts of P-N type flame retardant, 3 parts of synergist, 0.5 part of defoamer;

[0082] Among them, the reactive diluent is isooctyl acrylate; the photoinitiator is 1-hydroxycyclohexyl phenyl ketone; the P-N type flame retardant is prepared from Preparation Example 1; the synergist is obtained by mixing zirconium α-phosphate, organic bentonite and calcium metaborate in a mass ratio of 1:1:1; the defoamer is BYK-051;

[0083] A preparation method of a flame-retardant UV curable adhesive, comprising the following steps:

[0084] According to the formula, mix the acrylic resin, reactive diluent and defoamer, heat up to 50 °C, stir for 1 h, heat up to 80 °C, add polyvinyl alcohol, mercaptopropyl isobutyl silsesquioxane, P-N type flame retardant and synergist, and stir for 1 h; cool down to 50 °C, add the photoinitiator, and stir for 1 h to obtain the flame-retardant UV curable adhesive.

[0085] Example 8:

[0086] Example 8 is different from Example 1 only in that the synergist is obtained by mixing zirconium α-phosphate, organic bentonite and calcium metaborate in a mass ratio of 1:5:4, specifically as follows:

[0087] A flame-retardant UV curable adhesive, comprising the following raw materials in parts by weight: 40 parts of acrylic resin, 20 parts of reactive diluent, 20 parts of polyvinyl alcohol, 10 parts of mercaptopropyl isobutyl silsesquioxane, 3 parts of photoinitiator, 10 parts of P-N type flame retardant, 3 parts of synergist, 0.5 part of defoamer;

[0088] Among them, the reactive diluent is isooctyl acrylate; the photoinitiator is 1-hydroxycyclohexyl phenyl ketone; the P-N type flame retardant is prepared from Preparation Example 1; the synergist is obtained by mixing zirconium α-phosphate, organic bentonite and calcium metaborate in a mass ratio of 1:5:4; the defoamer is BYK-051;

[0089] A preparation method of a flame-retardant UV curable adhesive, comprising the following steps:

[0090] According to the formula, mix the acrylic resin, reactive diluent and defoamer, heat up to 50 °C, stir for 1 h, heat up to 80 °C, add polyvinyl alcohol, mercaptopropyl isobutyl silsesquioxane, P-N type flame retardant and synergist, and stir for 1 h; cool down to 50 °C, add the photoinitiator, and stir for 1 h to obtain the flame-retardant UV curable adhesive.

[0091] In order to verify the performance of the flame-retardant UV curable adhesives obtained in Examples 1-8 of the present invention, Comparative Examples 1-4 were set up in the present invention.

[0092] Comparative Example 1:

[0093] Comparative Example 1 is different from Example 1 only in that the P-N type flame retardant is prepared from Preparation Example 4, specifically as follows:

[0094] A flame-retardant UV-curable adhesive, comprising the following raw materials in parts by weight: 40 parts of acrylic resin, 20 parts of reactive diluent, 20 parts of polyvinyl alcohol, 10 parts of mercaptopropyl isobutyl silsesquioxane, 3 parts of photoinitiator, 10 parts of P-N type flame retardant, 3 parts of synergist, 0.5 part of defoamer;

[0095] Among them, the reactive diluent is isooctyl acrylate; the photoinitiator is 1-hydroxycyclohexyl phenyl ketone; the P-N type flame retardant is prepared by Preparation Example 4; the synergist is organic bentonite; the defoamer is BYK-051;

[0096] A preparation method of a flame-retardant UV-curable adhesive, comprising the following steps:

[0097] According to the formula, mix the acrylic resin, reactive diluent and defoamer, heat up to 50 °C, stir for 1 h, heat up to 80 °C, add polyvinyl alcohol, mercaptopropyl isobutyl silsesquioxane, P-N type flame retardant and synergist, and stir for 1 h; cool down to 50 °C, add the photoinitiator, and stir for 1 h to obtain the flame-retardant UV-curable adhesive.

[0098] Comparative Example 2:

[0099] Comparative Example 2 is different from Example 1 only in that an equal mass of piperazine pyrophosphate is used to replace the P-N type flame retardant (Preparation Example 1), specifically as follows:

[0100] A flame-retardant UV-curable adhesive, comprising the following raw materials in parts by weight: 40 parts of acrylic resin, 20 parts of reactive diluent, 20 parts of polyvinyl alcohol, 10 parts of mercaptopropyl isobutyl silsesquioxane, 3 parts of photoinitiator, 10 parts of piperazine pyrophosphate, 3 parts of synergist, 0.5 part of defoamer;

[0101] Among them, the reactive diluent is isooctyl acrylate; the photoinitiator is 1-hydroxycyclohexyl phenyl ketone; the synergist is organic bentonite; the defoamer is BYK-051;

[0102] A preparation method of a flame-retardant UV-curable adhesive, comprising the following steps:

[0103] According to the formula, mix the acrylic resin, reactive diluent and defoamer, heat up to 50 °C, stir for 1 h, heat up to 80 °C, add polyvinyl alcohol, mercaptopropyl isobutyl silsesquioxane, piperazine pyrophosphate and synergist, and stir for 1 h; cool down to 50 °C, add the photoinitiator, and stir for 1 h to obtain the flame-retardant UV-curable adhesive.

[0104] Comparative Example 3:

[0105] Comparative Example 3 is different from Example 1 only in that an equal mass of synergist is used to replace the P-N type flame retardant, specifically as follows:

[0106] A flame-retardant UV-curable adhesive, comprising the following raw materials in parts by weight: 40 parts of acrylic resin, 20 parts of reactive diluent, 20 parts of polyvinyl alcohol, 10 parts of mercaptopropyl isobutyl silsesquioxane, 3 parts of photoinitiator, 13 parts of P-N type flame retardant, 0.5 part of defoamer;

[0107] Among them, the reactive diluent is isooctyl acrylate; the photoinitiator is 1-hydroxycyclohexyl phenyl ketone; the P-N type flame retardant is prepared from Preparation Example 1; the defoamer is BYK-051;

[0108] A preparation method of a flame-retardant UV-curable adhesive, comprising the following steps:

[0109] According to the formula, mix the acrylic resin, reactive diluent and defoamer, heat up to 50 °C, stir for 1 h, heat up to 80 °C, add polyvinyl alcohol, mercaptopropyl isobutyl silsesquioxane and P-N type flame retardant, and stir for 1 h; cool down to 50 °C, add the photoinitiator, and stir for 1 h to obtain the flame-retardant UV-curable adhesive.

[0110] Comparative Example 4:

[0111] Comparative Example 4 is different from Example 1 only in that an equal mass of P-N type flame retardant is used to replace the synergist, specifically as follows:

[0112] A flame-retardant UV-curable adhesive, comprising the following raw materials in parts by weight: 40 parts of acrylic resin, 20 parts of reactive diluent, 20 parts of polyvinyl alcohol, 10 parts of mercaptopropyl isobutyl silsesquioxane, 3 parts of photoinitiator, 13 parts of synergist, 0.5 part of defoamer;

[0113] Among them, the reactive diluent is isooctyl acrylate; the photoinitiator is 1-hydroxycyclohexyl phenyl ketone; the synergist is organic bentonite; the defoamer is BYK-051;

[0114] A preparation method of a flame-retardant UV-curable adhesive, comprising the following steps:

[0115] According to the formula, mix the acrylic resin, reactive diluent and defoamer, heat up to 50 °C, stir for 1 h, heat up to 80 °C, add polyvinyl alcohol, mercaptopropyl isobutyl silsesquioxane and synergist, and stir for 1 h; cool down to 50 °C, add the photoinitiator, and stir for 1 h to obtain the flame-retardant UV-curable adhesive.

[0116] Performance testing:

[0117] 1. Measure the nuclear magnetic resonance hydrogen spectrum of the P-N type flame retardant obtained in Preparation Example 1 to obtain Figure 1 the hydrogen spectrum shown, and perform analysis: 1H NMR(CDCl 3, 500 MHz) δ 8.37 (s, 2H), 7.28 (s, 1H), 4.98 - 4.92 (m, 1H), 4.91 (d, J = 5.8 Hz, 0H), 4.64 (d, J = 6.2 Hz, 1H), 2.89 (dd, J = 11.0, 6.1 Hz, 1H), 2.81 - 2.72 (m, 1H), 2.67 - 2.59 (m, 3H), 2.47 (t, J = 5.7 Hz, 2H), 2.46 - 2.42 (m, 3H), 2.40 (s, 0H), 1.79 (p, J = 5.4 Hz, 2H), 1.65 (p, J = 5.7 Hz, 2H), 1.53 (t, J = 6.4 Hz, 2H), and the total hydrogen integration is 14, and the characteristic peak of the hydrogen in the [-NH-P=O] bond is found at 4.64, which can be used for the calibration of P-N type flame retardant molecules, fully indicating that each P-N type flame retardant molecule of the present invention contains three [-NH-P=O(OH)-O-] bonds, and the specific chemical structural formula is as follows:

[0118]

[0119] 2. Coating the obtained flame retardant UV curable adhesives in Examples 1 - 8 and Comparative Examples 1 - 4 of the present invention on one side of a polypropylene film, irradiating and curing with a 2000 mj 365 nm UV curing lamp for 20 min, and then winding to obtain a pressure-sensitive tape; performing performance tests on the pressure-sensitive tape, and the results are shown in Table 1:

[0120] Refer to GB / T2792 - 2014 "Test Method for Peel Strength of Adhesive Tapes" to test the peel strength of the pressure-sensitive tape;

[0121] Refer to the standard GB / T2408 - 2021 "Test Method for Flammability of Plastics Horizontal and Vertical Methods" to determine the flame retardant performance of the pressure-sensitive tape;

[0122] Refer to the standard GB / T2406.1 - 2008 "Plastics - Determination of Flammability by the Oxygen Index Method" to determine the oxygen index and dripping situation of the pressure-sensitive tape.

[0123] Table 1:

[0124]

[0125] As can be seen from the data shown in Table 1 above: The adhesives obtained in Examples 1 - 8 of the present invention have high peel strength, UL-94 vertical burning test grade of V-0, oxygen index above 35%, and no dripping during combustion, which are significantly better than those in Comparative Examples 1 - 4, fully indicating that the obtained adhesives of the present invention have good flame retardant effect, anti-dripping, excellent bonding performance and other characteristics, and have broad application prospects.

[0126] Comparing Example 1 with Comparative Examples 1 and 2, it can be seen that the P-N type flame retardant of the present invention can significantly enhance the peel strength of the adhesive and effectively inhibit the combustion of the adhesive. Comparing Example 1 with Comparative Examples 3 and 4, it can be seen that there is a synergistic effect between the P-N type flame retardant and the synergist, jointly improving the flame retardant performance of the adhesive, making its oxygen index reach more than 35%, passing the UL-94 vertical burning test at V-0 level, and there is no dripping and no obvious smoke generation during the combustion process.

[0127] This specific embodiment is only an explanation of the present invention and is not a limitation thereof. Those skilled in the art can make modifications to this embodiment without creative contributions according to needs after reading this specification, but as long as it is within the scope of the claims of the present invention, it is protected by the patent law.

Claims

1. A flame retardant UV curing adhesive, characterized in that: The invention comprises the following raw materials in parts by weight: 40-80 parts of acrylic resin, 20-50 parts of active diluent, 20-30 parts of polyvinyl alcohol, 10-20 parts of mercaptopropyl isobutyl cage-shaped silsesquioxane, 3-10 parts of photoinitiator, 10-20 parts of PN type flame retardant, 3-8 parts of synergist, and 0.5-2 parts of defoamer; The preparation method of the PN type flame retardant comprises the following steps: adding 1,4-bis(3-aminopropyl)piperazine to ethanol, mixing evenly, slowly adding an aqueous solution of phytic acid, and reacting at 60-70°C for 10-20 hours after the dropwise addition is completed within 5-10 minutes. After the reaction is completed, centrifuging, washing, drying, and purifying to obtain the PN type flame retardant; The synergist is obtained by mixing α-zirconium phosphate, organic bentonite and calcium metaborate in a mass ratio of 1:5:

4.

2. The flame retardant UV curing adhesive according to claim 1, characterized in that: The mass ratio of the aqueous solution of 1,4-bis(3-aminopropyl)piperazine, ethanol and phytic acid is 6g:40-60g:13.2-22g; The content of phytic acid in the aqueous solution of phytic acid is 30-50wt%.

3. The flame retardant UV curing adhesive according to claim 1, characterized in that: The active diluent is at least one of isooctyl acrylate, dipropylene glycol diacrylate, isobornyl acrylate, tetraethylene glycol dimethacrylate, neopentyl glycol diacrylate, diethylene glycol diacrylate, glycidyl methacrylate, and dodecyl methacrylate.

4. The flame retardant UV curing adhesive according to claim 1, characterized in that: The photoinitiator is at least one of 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methylphenyl acetone, (2,4,6-trimethylbenzoyl) diphenyl phosphine oxide, ethyl 2,4,6-trimethylbenzoyl phenyl phosphonate, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy) phenyl]-1-propanone and benzophenone.

5. The flame retardant UV curing adhesive according to claim 1, characterized in that: The defoaming agent is at least one of BYK-051, BYK-530, BYK-025, BYK-1723, BYK-1724, BYK-1611, and BYK-1617.

6. A method for preparing the flame retardant UV curing adhesive according to any one of claims 1 to 5, characterized in that: The following steps are involved: According to the formula, acrylic resin, active diluent and defoamer are mixed, heated to 50-70°C, stirred for 1-2 hours, heated to 80-90°C, polyvinyl alcohol, mercaptopropyl isobutyl cage silsesquioxane, PN flame retardant and synergist are added, and stirred for 1-2 hours; cooled to 50-75°C, photoinitiator is added, and stirred for 1-2 hours to obtain a flame retardant UV curing adhesive.

7. A flame retardant UV curing adhesive according to any one of claims 1 to 5 used in a pressure sensitive adhesive tape.

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