Ultrathin flexible hot melt adhesive film applied to body armor and preparation method of ultrathin flexible hot melt adhesive film

Abstract

The invention discloses an ultrathin flexible hot melt adhesive film applied to body armor and a preparation method of the ultrathin flexible hot melt adhesive film, and belongs to the technical field of preparation of hot melt adhesive films. The ultra-thin flexible hot melt adhesive film applied to the body armor is prepared from, by weight, 50-65 parts of ethylene-vinyl acetate copolymer, 22-34 parts of thermoplastic polyurethane elastomer, 8-12 parts of modified tackifier and 2-5 parts of modified antioxidant, the modified tackifier is prepared from tung oil, methyl alcohol, maleic anhydride, 1, 2-propylene glycol and 1, 3-propylene glycol, and the modified antioxidant is prepared from the following components in parts by weight: 1, 3-propylene glycol, 1, 3-propylene glycol and 1, 3-propylene glycol. The antioxidant is prepared from 1, 4-butanediol glycidyl ether, hydroxyethyl acrylamide, glycerol and gelatin, and the modified antioxidant is prepared from chitosan, sodium hydroxide, methanesulfonic acid and phosphorous acid. The ultrathin flexible hot melt adhesive film prepared by the method has excellent bonding strength, flexibility and oxidation resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of hot melt adhesive film preparation, and in particular relates to an ultra-thin flexible hot melt adhesive film used in bulletproof vests and a preparation method thereof. Background Art

[0002] As an important equipment to protect people from fatal injuries such as bullets and knives, the performance improvement of bulletproof vests has always been the focus of people's attention. Traditional bulletproof vests are mostly made of heavy metal or ceramic materials. Although the protective effect is significant, they are heavy and have poor flexibility, which seriously affects the wearer's mobility and comfort. Therefore, new lightweight and high-strength materials that can be used in bulletproof vests have emerged. Among them, high-strength fiber materials such as ultra-high molecular weight polyethylene fiber and aramid fiber have gradually become the preferred materials for the manufacture of bulletproof vests due to their excellent mechanical properties. However, the bonding problem of these materials has become a key factor restricting the further improvement of the performance of bulletproof vests.

[0003] The emergence of ultra-thin flexible hot melt adhesive film provides an effective solution to this problem. The hot melt adhesive film is made by advanced cast or blown film technology. The thickness is extremely thin, usually only a few microns to tens of microns, but it has extremely high bonding strength and good flexibility. It can be quickly heated and softened in a short time, and tightly combined with the fiber material in the bulletproof vest to form a solid protective layer. At the same time, due to its extremely thin thickness, it has little effect on the overall weight and thickness of the bulletproof vest, thus ensuring the wearer's mobility and comfort.

[0004] Patent CN108003819A discloses a PMMA ultra-thin hot melt adhesive film and its preparation method and use. The hot melt adhesive film is mainly used in traffic reflective film, which solves the shortcomings of existing hot melt adhesive films such as unstable residual melting, poor high temperature resistance, and poor weather resistance. The hot melt adhesive film is composed of PMMA, methyl methacrylate-butadiene-styrene terpolymer, and rutile titanium dioxide and thickener. The weight percentage is: PMMA 80%-90%, methyl methacrylate-butadiene-styrene terpolymer 3%-10%, rutile titanium dioxide 3%-10%, and thickener 1%-10%. However, the bonding strength, flexibility, and antioxidant properties of the hot melt adhesive film prepared by this method still have room for improvement. Summary of the invention

[0005] The purpose of the present invention is to provide an ultra-thin flexible hot-melt adhesive film used in bulletproof vests and a preparation method thereof, so as to solve the technical problems of poor bonding strength, flexibility and anti-oxidation performance of the hot-melt adhesive film in the prior art.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The invention provides an ultra-thin flexible hot-melt adhesive film applied to bulletproof vests. The ultra-thin flexible hot-melt adhesive film is composed of the following components in parts by weight: 50-65 parts of ethylene-vinyl acetate copolymer, 22-34 parts of thermoplastic polyurethane elastomer, 8-12 parts of modified tackifier, and 2-5 parts of modified antioxidant, wherein the modified tackifier is prepared from tung oil, methanol, maleic anhydride, 1,4-butanediol glycidyl ether, hydroxyethyl acrylamide, glycerol and gelatin, and the modified antioxidant is prepared from chitosan, sodium hydroxide, methanesulfonic acid and phosphorous acid.

[0007] Preferably, the preparation method of the modified tackifier comprises the following steps: Q1: Add tung oil, methanol and potassium hydroxide to a container equipped with a stirrer and a condenser, heat in a water bath for reaction, and after the reaction is completed, stand for stratification, take the upper layer of liquid for washing, heat and rotary evaporate to obtain a light yellow oily liquid; add the light yellow oily liquid and maleic anhydride to a container, introduce nitrogen, heat for reaction, cool, dissolve, adjust pH, rotary evaporate, add cyclohexane and deionized water, take the water layer, add sodium hydroxide, heat and react, add hydrochloric acid dropwise after heating, dissolve, dry, and rotary evaporate to obtain a white solid; Q2: Add the white solid and 1,4-butanediol glycidyl ether to isobutyl alcohol, heat to reflux, and after the reflux is completed, rotary evaporate to obtain a brown substance; Q3: Add hydroxyethyl acrylamide and glycerol into a container, then add a mixed solution of gelatin and phytic acid, heat and stir to react, then add 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone, after the reaction, add brown substance, continue stirring to obtain a precursor solution, cool, place at low temperature, and UV cure to obtain a modified toughening agent.

[0008] In the above process, tung oil is first used as a raw material to prepare a light yellow oily liquid, which is then subjected to a Diels-Alder reaction with maleic anhydride to obtain a brown substance, and then phytic acid and glycerol are used as binary solvents, hydroxyethyl acrylamide and gelatin are used as raw materials, and a modified toughening agent containing a network structure is prepared by ultraviolet curing, wherein the synthesis reaction formula of the brown substance is as follows:

[0009] The results of mass spectrometry analysis of the light yellow oily liquid were: m / z: 292.24 (100.0%), 293.24 (20.6%), 294.25 (2.1%); the results of mass spectrometry analysis of the white solid were: m / z: 394.24 (100.0%), 395.24 (24.4%), 396.24 (4.0%).

[0010] Preferably, in Q1, the amount ratio of tung oil, methanol and potassium hydroxide is (200-250) g: (54-81) g: (3-4.5) g, the reaction temperature in a water bath is 70-80°C, the time is 1-2 h, the mixture is washed with saturated sodium chloride and deionized water until neutral, and the temperature of heated rotary evaporation is 70-75°C; the amount ratio of light yellow oily liquid, maleic anhydride, cyclohexane and deionized water is (28-32) g: (9.2-10.3) g: (100-120) mL: (400-450) mL, the reaction temperature is 85-90°C, the time is 2-3 h, the mixture is cooled to 28-32°C, added to acetone for dissolution, the pH is adjusted to 7-7.2 with 50wt% sodium hydroxide solution, the reaction temperature is 70-80°C, the time is 2-3 h, the mixture is added to ethyl acetate for dissolution, and dried with anhydrous sodium sulfate.

[0011] Preferably, in Q2, the amount ratio of the white solid, 1,4-butanediol glycidyl ether and isobutyl alcohol is (15-17) g: (10-12) g: (40-50) mL, and the heating reflux temperature is 105-110° C. for 45-50 h.

[0012] Preferably, in Q3, the dosage ratio of hydroxyethyl acrylamide, glycerol, gelatin, phytic acid, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone and brown substance is (6-10) g: (8-12) mL: (3-4) g: (8-12) mL: (0.05-0.08) g: (2-2.5) g, the heating and stirring reaction temperature is 60-70°C, the time is 3-5h, the continued stirring time is 2-3h, the low temperature placement temperature is 3-5°C, the time is 30-45min, and the UV curing time is 5-10min.

[0013] Preferably, the preparation method of the modified antioxidant comprises the following steps: S1: adding chitosan to a sodium hydroxide solution, stirring the solution sufficiently, and then sealing and freezing the solution. After the solution is thawed, the solution is filtered, and dried to obtain modified chitosan. S2: Add the modified chitosan to the methanesulfonic acid solution, stir it thoroughly, transfer it to a container containing the phosphorous acid solution, stir it evenly, heat it, add the formaldehyde solution dropwise, condense and reflux it, after the reaction is completed, cool it, dialyze it, and distill it under reduced pressure to obtain a concentrated solution, add a mixture of anhydrous ethanol and acetone to the concentrated solution, precipitate it, let it stand, filter it, wash it, and dry it in vacuo to obtain a modified antioxidant.

[0014] In the above process, the synthetic reaction formula of the modified antioxidant is as follows:

[0015] Preferably, in S1, the ratio of chitosan to sodium hydroxide solution is (20-30) g: (50-70) mL, the mass fraction of the sodium hydroxide solution is 50 wt %, and the treatment time is 10-12 days.

[0016] Preferably, in S2, the dosage ratio of modified chitosan, methanesulfonic acid solution, phosphorous acid solution and formaldehyde solution is (0.5-0.75) g: (150-225) mL: (6-8) mL: (6-8) mL, the mass fraction of methanesulfonic acid solution is 5wt%, the volume fraction of phosphorous acid solution is 40vt%, the mass fraction of formaldehyde solution is 40wt%, the stirring time is 1-2h, the temperature is raised to 65-75°C, the condensation reflux reaction time is 4-8h, and the temperature is cooled to 28-32°C. During the dialysis process, the molecular weight cutoff of the dialysis bag is 12000kDa, the dialysis time is 68-72h, the standing time is 10-12h, the vacuum drying temperature is 50-60°C, and the time is 8-12h.

[0017] Preferably, the method for preparing the ultra-thin flexible hot melt adhesive film used in bulletproof vests comprises the following steps: Step (1): adding ethylene-vinyl acetate copolymer and thermoplastic polyurethane elastomer into a reaction vessel equipped with an electric heating jacket and a stirrer, heating and melting and mixing uniformly to obtain a resin mixture; Step (2): Add a modified tackifier and a modified antioxidant to the resin mixture, continue stirring, then add the mixture to a casting machine, extrude, cool, wind, cut, and inspect to obtain an ultra-thin flexible hot melt adhesive film for use in bulletproof vests.

[0018] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. The present invention first uses tung oil, methanol, maleic anhydride, 1,4-butanediol glycidyl ether, hydroxyethyl acrylamide, glycerol and gelatin as raw materials to prepare a modified thickener, and then uses chitosan, sodium hydroxide, methanesulfonic acid and phosphorous acid as raw materials to prepare a modified antioxidant. The obtained modified thickener and modified antioxidant are added into the preparation process of an ultra-thin flexible hot-melt adhesive film used in bulletproof vests, which can effectively improve its bonding strength, flexibility and antioxidant properties.

[0019] 2. The present invention adds the prepared modified tackifier to the ultra-thin flexible hot-melt adhesive film, which can effectively improve its bonding strength and flexibility. Tung oil, as a natural vegetable oil, has multiple conjugated double bonds in its molecular structure with high chemical reactivity. It reacts with maleic anhydride to generate a brown substance, which is added to an organic gel formed by physical crosslinking of polymer compounds such as polyhydroxyethyl acrylate and gelatin. The molecular segments contained in the brown substance can interact with other components in the organic gel to form a more complex network structure, thereby significantly enhancing the flexibility of the entire system. At the same time, the modified tackifier has good wettability and permeability, can quickly penetrate into the surface of the substrate and form a uniform coating, which helps to enhance the bonding strength of the hot-melt adhesive film, and the organic gel contained in the modified tackifier has self-healing ability. When it is damaged, the internal molecular segments can be rearranged and new crosslinking points can be formed, thereby restoring its original structure and performance.

[0020] 3. The present invention adds the prepared modified antioxidant to the ultra-thin flexible hot-melt adhesive film, which can effectively improve its antioxidant properties. The phosphorus atom in the phosphate group in the modified antioxidant has a pentavalent state, can form multiple covalent bonds, and has high chemical stability. When free radicals attack the phosphate group, the phosphorus atom can combine with the unpaired electrons in the free radical to form a stable chemical bond, thereby preventing the chain reaction of the free radical. The chitosan molecular chain contains a large number of amino and hydroxyl groups with high reactivity, which can also react with the free radicals to prevent them from further initiating a chain reaction, thereby improving the antioxidant properties of the ultra-thin flexible hot-melt adhesive film. DETAILED DESCRIPTION

[0021] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Example 1: This example discloses a method for preparing a modified tackifier, comprising the following steps: Q1: Add 225g of tung oil, 69.5g of methanol and 3.75g of potassium hydroxide to a container equipped with a stirrer and a condenser, heat in a water bath at 80°C for 2h, and after the reaction is completed, let it stand for stratification, take the upper layer of liquid, wash it with saturated sodium chloride and deionized water until neutral, heat and evaporate it at 75°C to obtain a light yellow oily liquid; add 30g of light yellow oily liquid and 9.7g of maleic anhydride to a container, introduce nitrogen, heat and react at 90°C for 2h, cool to 28°C, add to acetone for dissolution, adjust pH to 7 with 50wt% sodium hydroxide solution, evaporate it, add 110mL of cyclohexane and 425mL of deionized water, take the water layer, add sodium hydroxide, heat and react at 80°C for 3h, then drop hydrochloric acid, add to ethyl acetate for dissolution, dry with anhydrous sodium sulfate, evaporate it, and obtain a white solid; Q2: Add 16 g of white solid and 11 g of 1,4-butanediol glycidyl ether to 45 mL of isobutyl alcohol, heat and reflux at 110 °C for 48 h, and after reflux, rotary evaporate to obtain a brown substance; Q3: Add 8g of hydroxyethyl acrylamide and 10mL of glycerol into a container, then add a mixed solution of 3.5g of gelatin and 10mL of phytic acid, heat and stir at 65°C for 5h, then add 0.06g of 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone, after the reaction, add 2.25g of brown substance, continue stirring for 3h to obtain a precursor solution, cool, place at 3°C ​​for 45min, and UV cure for 10min to obtain a modified toughening agent.

[0023] This embodiment discloses a method for preparing a modified antioxidant, comprising the following steps: S1: adding 25 g of chitosan to 60 mL of 50 wt% sodium hydroxide solution, stirring thoroughly, sealing and freezing for 12 days, thawing after the treatment, filtering, and drying to obtain modified chitosan; S2: Add 0.62g of modified chitosan to 185mL of 5wt% methanesulfonic acid solution, stir thoroughly, transfer to a container containing 7mL of 40vt% phosphorous acid solution, stir evenly for 2h, heat to 65℃, drop 7mL of 40wt% formaldehyde solution, condense and reflux for 6h, after the reaction is completed, cool to 28℃, dialyze for 72h using a dialysis bag with a molecular weight cutoff of 12000kDa, distill under reduced pressure to obtain a concentrated solution, add a mixture of anhydrous ethanol and acetone to the concentrated solution, precipitate, let stand for 12h, filter, wash, and dry under vacuum at 60℃ for 12h to obtain a modified antioxidant.

[0024] The present embodiment discloses an ultra-thin flexible hot melt adhesive film used in bulletproof vests, which is composed of the following components in parts by weight: 57.5 parts of ethylene-vinyl acetate copolymer, 28 parts of thermoplastic polyurethane elastomer, 10 parts of modified tackifier, and 3.5 parts of modified antioxidant.

[0025] This embodiment discloses a method for preparing an ultra-thin flexible hot melt adhesive film used in bulletproof vests, comprising the following steps: Step (1): adding ethylene-vinyl acetate copolymer and thermoplastic polyurethane elastomer into a reaction vessel equipped with an electric heating jacket and a stirrer, heating and melting and mixing uniformly to obtain a resin mixture; Step (2): Add a modified tackifier and a modified antioxidant to the resin mixture, continue stirring, then add the mixture to a casting machine, extrude, cool, wind, cut, and inspect to obtain an ultra-thin flexible hot melt adhesive film for use in bulletproof vests.

[0026] Example 2: This example discloses a method for preparing a modified tackifier, comprising the following steps: Q1: 200g tung oil, 54g methanol and 4.5g potassium hydroxide were added to a container equipped with a stirrer and a condenser, and the mixture was heated in a water bath at 80°C for 2h. After the reaction was completed, the mixture was allowed to stand for stratification, and the upper layer of liquid was washed with saturated sodium chloride and deionized water until neutral, and then heated and rotary evaporated at 75°C to obtain a light yellow oily liquid; 32g of light yellow oily liquid and 10.3g of maleic anhydride were added to a container, nitrogen was introduced, and the mixture was heated at 90°C for 2h, cooled to 28°C, added to acetone for dissolution, and the pH was adjusted to 7 with a 50wt% sodium hydroxide solution, and rotary evaporated, 120mL of cyclohexane and 400mL of deionized water were added, the water layer was taken, sodium hydroxide was added, and the mixture was heated at 80°C for 3h, and then hydrochloric acid was added dropwise, and the mixture was added to ethyl acetate for dissolution, dried with anhydrous sodium sulfate, and rotary evaporated to obtain a white solid; Q2: Add 15 g of white solid and 10 g of 1,4-butanediol glycidyl ether to 50 mL of isobutyl alcohol, heat and reflux at 110 °C for 48 h, and after reflux, rotary evaporate to obtain a brown substance; Q3: Add 10g of hydroxyethyl acrylamide and 12mL of glycerol into a container, then add a mixed solution of 4g of gelatin and 8mL of phytic acid, heat and stir at 65°C for 5h, then add 0.08g of 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone, after the reaction, add 2.5g of brown substance, continue stirring for 3h to obtain a precursor solution, cool, place at 3°C ​​for 45min, and UV cure for 10min to obtain a modified toughening agent.

[0027] This embodiment discloses a method for preparing a modified antioxidant, comprising the following steps: S1: adding 20 g of chitosan to 70 mL of 50 wt% sodium hydroxide solution, stirring thoroughly, sealing and freezing for 12 days, thawing after the treatment, filtering, and drying to obtain modified chitosan; S2: Add 0.5g of modified chitosan to 150mL of 5wt% methanesulfonic acid solution, stir thoroughly, transfer to a container containing 6mL of 40vt% phosphorous acid solution, stir evenly for 2h, heat to 65℃, drop 8mL of 40wt% formaldehyde solution, condense and reflux for 6h, after the reaction is completed, cool to 28℃, dialyze for 72h using a dialysis bag with a molecular weight cutoff of 12000kDa, distill under reduced pressure to obtain a concentrated solution, add a mixture of anhydrous ethanol and acetone to the concentrated solution, precipitate, let stand for 12h, filter, wash, and dry under vacuum at 60℃ for 12h to obtain a modified antioxidant.

[0028] The present embodiment discloses an ultra-thin flexible hot melt adhesive film used in bulletproof vests, which is composed of the following components in parts by weight: 50 parts of ethylene-vinyl acetate copolymer, 22 parts of thermoplastic polyurethane elastomer, 12 parts of modified tackifier, and 5 parts of modified antioxidant.

[0029] This embodiment discloses a method for preparing an ultra-thin flexible hot melt adhesive film used in bulletproof vests, comprising the following steps: Step (1): adding ethylene-vinyl acetate copolymer and thermoplastic polyurethane elastomer into a reaction vessel equipped with an electric heating jacket and a stirrer, heating and melting and mixing uniformly to obtain a resin mixture; Step (2): Add a modified tackifier and a modified antioxidant to the resin mixture, continue stirring, then add the mixture to a casting machine, extrude, cool, wind, cut, and inspect to obtain an ultra-thin flexible hot melt adhesive film for use in bulletproof vests.

[0030] Example 3: This example discloses a method for preparing a modified tackifier, comprising the following steps: Q1: Add 250g tung oil, 81g methanol and 3g potassium hydroxide to a container equipped with a stirrer and a condenser, heat in a water bath at 80°C for 2h, and after the reaction is completed, let it stand for stratification, take the upper layer of liquid, wash it with saturated sodium chloride and deionized water until neutral, heat and evaporate it at 75°C to obtain a light yellow oily liquid; add 28g of light yellow oily liquid and 9.2g of maleic anhydride to a container, introduce nitrogen, heat and react at 90°C for 2h, cool to 28°C, add to acetone for dissolution, adjust pH to 7 with 50wt% sodium hydroxide solution, evaporate it, add 100mL cyclohexane and 450mL deionized water, take the water layer, add sodium hydroxide, heat and react at 80°C for 3h, then add hydrochloric acid dropwise, add to ethyl acetate for dissolution, dry with anhydrous sodium sulfate, evaporate it, and obtain a white solid; Q2: Add 17 g of white solid and 12 g of 1,4-butanediol glycidyl ether to 40 mL of isobutyl alcohol, heat and reflux at 110 °C for 48 h, and after reflux, rotary evaporate to obtain a brown substance; Q3: Add 6g of hydroxyethyl acrylamide and 8mL of glycerol into a container, then add a mixed solution of 3g of gelatin and 12mL of phytic acid, heat and stir at 65°C for 5h, then add 0.05g of 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone, after the reaction, add 2g of brown substance, continue stirring for 3h to obtain a precursor solution, cool, place at 3°C ​​for 45min, and UV cure for 10min to obtain a modified toughening agent.

[0031] This embodiment discloses a method for preparing a modified antioxidant, comprising the following steps: S1: 30 g of chitosan was added to 50 mL of 50 wt% sodium hydroxide solution, and the mixture was sealed and frozen for 12 days after being fully stirred. After the treatment, the mixture was thawed, filtered, and dried to obtain modified chitosan; S2: Add 0.75g of modified chitosan to 225mL of 5wt% methanesulfonic acid solution, stir thoroughly, transfer to a container containing 8mL of 40vt% phosphorous acid solution, stir evenly for 2h, heat to 65℃, drop 6mL of 40wt% formaldehyde solution, condense and reflux for 6h, after the reaction is completed, cool to 28℃, dialyze for 72h using a dialysis bag with a molecular weight cutoff of 12000kDa, distill under reduced pressure to obtain a concentrated solution, add a mixture of anhydrous ethanol and acetone to the concentrated solution, precipitate, let stand for 12h, filter, wash, and dry under vacuum at 60℃ for 12h to obtain a modified antioxidant.

[0032] The present embodiment discloses an ultra-thin flexible hot melt adhesive film used in bulletproof vests, which is composed of the following components in parts by weight: 65 parts of ethylene-vinyl acetate copolymer, 34 parts of thermoplastic polyurethane elastomer, 8 parts of modified tackifier, and 2 parts of modified antioxidant.

[0033] This embodiment discloses a method for preparing an ultra-thin flexible hot melt adhesive film used in bulletproof vests, comprising the following steps: Step (1): adding ethylene-vinyl acetate copolymer and thermoplastic polyurethane elastomer into a reaction vessel equipped with an electric heating jacket and a stirrer, heating and melting and mixing uniformly to obtain a resin mixture; Step (2): Add a modified tackifier and a modified antioxidant to the resin mixture, continue stirring, then add the mixture to a casting machine, extrude, cool, wind, cut, and inspect to obtain an ultra-thin flexible hot melt adhesive film for use in bulletproof vests.

[0034] Example 4: This example discloses a method for preparing a modified tackifier, comprising the following steps: Q1: Add 210g tung oil, 62g methanol and 3.2g potassium hydroxide to a container equipped with a stirrer and a condenser, heat in a water bath at 80°C for 2h, and after the reaction is completed, let it stand for stratification, take the upper layer of liquid, wash it with saturated sodium chloride and deionized water until neutral, heat and evaporate it at 75°C to obtain a light yellow oily liquid; add 29g of light yellow oily liquid and 9.4g of maleic anhydride to a container, introduce nitrogen, heat and react at 90°C for 2h, cool to 28°C, add to acetone for dissolution, adjust pH to 7 with 50wt% sodium hydroxide solution, evaporate it, add 105mL cyclohexane and 410mL deionized water, take the water layer, add sodium hydroxide, heat and react at 80°C for 3h, then drop hydrochloric acid, add to ethyl acetate for dissolution, dry with anhydrous sodium sulfate, evaporate it, and obtain a white solid; Q2: Add 15.5 g of white solid and 10.5 g of 1,4-butanediol glycidyl ether to 42.5 mL of isobutyl alcohol, heat and reflux at 110 °C for 48 h, and after reflux, rotary evaporate to obtain a brown substance; Q3: Add 9 g of hydroxyethyl acrylamide and 9 mL of glycerol to a container, followed by a mixed solution of 3.2 g of gelatin and 11 mL of phytic acid, heat and stir at 65 °C for 5 h, then add 0.07 g of 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone. After the reaction, add 2.1 g of brown substance and continue stirring for 3 h to obtain a precursor solution. Cool, place at 3 °C for 45 min, and UV cure for 10 min to obtain a modified toughening agent.

[0035] This embodiment discloses a method for preparing a modified antioxidant, comprising the following steps: S1: adding 22 g of chitosan to 55 mL of 50 wt% sodium hydroxide solution, stirring thoroughly, sealing and freezing for 12 days, thawing after the treatment, filtering, and drying to obtain modified chitosan; S2: Add 0.55g of modified chitosan to 160mL of 5wt% methanesulfonic acid solution, stir thoroughly, transfer to a container containing 6.5mL of 40wt% phosphorous acid solution, stir evenly for 2h, heat to 65℃, drop 6.5mL of 40wt% formaldehyde solution, condense and reflux for 6h, after the reaction is completed, cool to 28℃, dialyze for 72h using a dialysis bag with a molecular weight cutoff of 12000kDa, distill under reduced pressure to obtain a concentrated solution, add a mixture of anhydrous ethanol and acetone to the concentrated solution, precipitate, let stand for 12h, filter, wash, and dry under vacuum at 60℃ for 12h to obtain a modified antioxidant.

[0036] The present embodiment discloses an ultra-thin flexible hot melt adhesive film used in bulletproof vests, which is composed of the following components in parts by weight: 55 parts of ethylene-vinyl acetate copolymer, 26 parts of thermoplastic polyurethane elastomer, 9 parts of modified tackifier, and 2.5 parts of modified antioxidant.

[0037] This embodiment discloses a method for preparing an ultra-thin flexible hot melt adhesive film used in bulletproof vests, comprising the following steps: Step (1): adding ethylene-vinyl acetate copolymer and thermoplastic polyurethane elastomer into a reaction vessel equipped with an electric heating jacket and a stirrer, heating and melting and mixing uniformly to obtain a resin mixture; Step (2): Add a modified tackifier and a modified antioxidant to the resin mixture, continue stirring, then add the mixture to a casting machine, extrude, cool, wind, cut, and inspect to obtain an ultra-thin flexible hot melt adhesive film for use in bulletproof vests.

[0038] Example 5: This example discloses a method for preparing a modified tackifier, comprising the following steps: Q1: 240g tung oil, 73g methanol and 4.1g potassium hydroxide were added to a container equipped with a stirrer and a condenser, and the mixture was heated in a water bath at 80°C for 2h. After the reaction was completed, the mixture was allowed to stand for stratification, and the upper layer of liquid was washed with saturated sodium chloride and deionized water until neutral, and then heated and rotary evaporated at 75°C to obtain a light yellow oily liquid; 31g of light yellow oily liquid and 10.17g of maleic anhydride were added to a container, nitrogen was introduced, and the mixture was heated at 90°C for 2h, cooled to 28°C, and added to acetone for dissolution, and the pH was adjusted to 7 with a 50wt% sodium hydroxide solution, and rotary evaporated, 115mL of cyclohexane and 440mL of deionized water were added, the water layer was taken, sodium hydroxide was added, and the mixture was heated at 80°C for 3h, and then hydrochloric acid was added dropwise, and the mixture was added to ethyl acetate for dissolution, and the mixture was dried with anhydrous sodium sulfate, and rotary evaporated to obtain a white solid; Q2: Add 16.5 g of white solid and 11.5 g of 1,4-butanediol glycidyl ether to 47.5 mL of isobutyl alcohol, heat and reflux at 110 °C for 48 h, and after reflux, rotary evaporate to obtain a brown substance; Q3: Add 7g of hydroxyethyl acrylamide and 11mL of glycerol to a container, followed by a mixed solution of 3.8g of gelatin and 9mL of phytic acid, heat and stir at 65°C for 5h, then add 0.06g of 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone, after the reaction, add 2.4g of brown substance, continue stirring for 3h to obtain a precursor solution, cool, place at 3°C ​​for 45min, and UV cure for 10min to obtain a modified toughening agent.

[0039] This embodiment discloses a method for preparing a modified antioxidant, comprising the following steps: S1: adding 28 g of chitosan to 65 mL of 50 wt% sodium hydroxide solution, stirring thoroughly, sealing and freezing for 12 days, thawing after the treatment, filtering, and drying to obtain modified chitosan; S2: Add 0.7g of modified chitosan to 210mL of 5wt% methanesulfonic acid solution, stir thoroughly, transfer to a container containing 7.5mL of 40wt% phosphorous acid solution, stir evenly for 2h, heat to 65℃, drop 7.5mL of 40wt% formaldehyde solution, condense and reflux for 6h, after the reaction is completed, cool to 28℃, dialyze for 72h using a dialysis bag with a molecular weight cutoff of 12000kDa, distill under reduced pressure to obtain a concentrated solution, add a mixture of anhydrous ethanol and acetone to the concentrated solution, precipitate, let stand for 12h, filter, wash, and dry under vacuum at 60℃ for 12h to obtain a modified antioxidant.

[0040] The present embodiment discloses an ultra-thin flexible hot melt adhesive film used in bulletproof vests, which is composed of the following components in parts by weight: 60 parts of ethylene-vinyl acetate copolymer, 32 parts of thermoplastic polyurethane elastomer, 11 parts of modified tackifier, and 4.5 parts of modified antioxidant.

[0041] This embodiment discloses a method for preparing an ultra-thin flexible hot melt adhesive film used in bulletproof vests, comprising the following steps: Step (1): adding ethylene-vinyl acetate copolymer and thermoplastic polyurethane elastomer into a reaction vessel equipped with an electric heating jacket and a stirrer, heating and melting and mixing uniformly to obtain a resin mixture; Step (2): Add a modified tackifier and a modified antioxidant to the resin mixture, continue stirring, then add the mixture to a casting machine, extrude, cool, wind, cut, and inspect to obtain an ultra-thin flexible hot melt adhesive film for use in bulletproof vests.

[0042] Comparative Example 1: Compared with Example 1, in the process of preparing the modified tackifier in Comparative Example 1, no tung oil was added, and other conditions remained unchanged.

[0043] Comparative Example 2: Compared with Example 1, in the process of preparing the modified antioxidant in Comparative Example 2, no chitosan was added, and other conditions remained unchanged.

[0044] Comparative Example 3: Compared with Example 1, in the process of preparing the ultra-thin flexible hot-melt adhesive film in Comparative Example 3, no modified tackifier is added, and other conditions remain unchanged.

[0045] Comparative Example 4: Compared with Example 1, in Comparative Example 4, during the process of preparing the ultra-thin flexible hot-melt adhesive film, no modified antioxidant was added, and other conditions remained unchanged.

[0046] Experimental example: The elongation at break of the sample was tested according to GB / T 30776-2014, and the bonding strength of the sample was determined by tower shear. The prepared sample was placed between the surface of wood and plastic. The wood and plastic were clamped with a binder clip for 3 minutes before the test to ensure good contact between the two and the sample. After curing, a tensile test was performed using a tensile machine. The bonding strength was calculated by dividing the maximum load by the corresponding bonding area. The aging resistance of the sample was tested according to GB / T 7141-2008. The test results are shown in Table 1: Table 1 project Elongation at break / % Adhesion strength / MPa Adhesion strength reduction rate / % Example 1 115.6 10.24 1.32 Example 2 114.8 10.18 1.37 Example 3 114.9 10.14 1.42 Example 4 115.1 10.12 1.41 Example 5 114.6 10.09 1.44 Comparative Example 1 102.3 8.23 1.45 Comparative Example 2 114.5 10.03 3.89 Comparative Example 3 100.5 8.14 1.47 Comparative Example 4 114.3 10.02 3.95 It can be seen from the test results in Table 1 that the ultra-thin flexible hot melt adhesive film prepared in Examples 1-5 of the present invention has excellent flexibility, bonding strength and antioxidant properties. By comparing Comparative Example 1 with Examples 1-5, it can be seen that the addition of tung oil can effectively improve the flexibility and bonding strength of the ultra-thin flexible hot melt adhesive film; by comparing Comparative Example 2 with Examples 1-5, it can be seen that the addition of chitosan can effectively improve the antioxidant properties of the ultra-thin flexible hot melt adhesive film; by comparing Comparative Example 3 with Examples 1-5, it can be seen that the addition of a modified tackifier can effectively improve the flexibility and bonding strength of the ultra-thin flexible hot melt adhesive film; by comparing Comparative Example 4 with Examples 1-5, it can be seen that the addition of a modified antioxidant can effectively improve the antioxidant properties of the ultra-thin flexible hot melt adhesive film.

[0047] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

[0048] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. An ultra-thin flexible hot melt adhesive film used in bulletproof vests, characterized in that: The invention is composed of the following components in parts by weight: 50-65 parts of ethylene-vinyl acetate copolymer, 22-34 parts of thermoplastic polyurethane elastomer, 8-12 parts of modified tackifier, and 2-5 parts of modified antioxidant, wherein the modified tackifier is prepared from tung oil, methanol, maleic anhydride, 1,4-butanediol glycidyl ether, hydroxyethyl acrylamide, glycerol and gelatin, and the modified antioxidant is prepared from chitosan, sodium hydroxide, methanesulfonic acid and phosphorous acid.

2. The ultra-thin flexible hot melt adhesive film for use in bulletproof vests according to claim 1, characterized in that: The preparation method of the modified tackifier comprises the following steps: Q1: Add tung oil, methanol and potassium hydroxide to a container equipped with a stirrer and a condenser, heat in a water bath for reaction, and after the reaction is completed, stand for stratification, take the upper layer of liquid for washing, heat and rotary evaporate to obtain a light yellow oily liquid; add the light yellow oily liquid and maleic anhydride to a container, introduce nitrogen, heat for reaction, cool, dissolve, adjust pH, rotary evaporate, add cyclohexane and deionized water, take the water layer, add sodium hydroxide, heat and react, add hydrochloric acid dropwise after heating, dissolve, dry, and rotary evaporate to obtain a white solid; Q2: Add the white solid and 1,4-butanediol glycidyl ether to isobutyl alcohol, heat to reflux, and after the reflux is completed, rotary evaporate to obtain a brown substance; Q3: Add hydroxyethyl acrylamide and glycerol into a container, then add a mixed solution of gelatin and phytic acid, heat and stir to react, then add 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone, after the reaction, add brown substance, continue stirring to obtain a precursor solution, cool, place at low temperature, and UV cure to obtain a modified toughening agent.

3. The ultra-thin flexible hot melt adhesive film for use in bulletproof vests according to claim 2, characterized in that: In the Q1, the amount ratio of tung oil, methanol and potassium hydroxide is (200-250) g: (54-81) g: (3-4.5) g, the reaction temperature in a water bath is 70-80°C, the time is 1-2 h, the product is washed with saturated sodium chloride and deionized water until neutral, and the temperature of heated rotary evaporation is 70-75°C; the amount ratio of light yellow oily liquid, maleic anhydride, cyclohexane and deionized water is (28-32) g: (9.2-10.3) g: (100-120) mL: (400-450) mL, the reaction temperature is 85-90°C, the time is 2-3 h, the product is cooled to 28-32°C, added to acetone for dissolution, the pH is adjusted to 7-7.2 with 50wt% sodium hydroxide solution, the reaction temperature is 70-80°C, the time is 2-3 h, the product is added to ethyl acetate for dissolution, and dried with anhydrous sodium sulfate.

4. The ultra-thin flexible hot melt adhesive film for use in bulletproof vests according to claim 2, characterized in that: In the Q2, the dosage ratio of the white solid, 1,4-butanediol glycidyl ether and isobutyl alcohol is (15-17) g: (10-12) g: (40-50) mL, the heating reflux temperature is 105-110° C., and the time is 45-50 h.

5. The ultra-thin flexible hot melt adhesive film for use in bulletproof vests according to claim 2, characterized in that: In Q3, the dosage ratio of hydroxyethyl acrylamide, glycerol, gelatin, phytic acid, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone and brown substance is (6-10) g: (8-12) mL: (3-4) g: (8-12) mL: (0.05-0.08) g: (2-2.5) g, the heating and stirring reaction temperature is 60-70°C, the time is 3-5h, the stirring time is continued for 2-3h, the low temperature storage temperature is 3-5°C, the time is 30-45min, and the UV curing time is 5-10min.

6. The ultra-thin flexible hot melt adhesive film for use in bulletproof vests according to claim 1, characterized in that: The preparation method of the modified antioxidant comprises the following steps: S1: adding chitosan to a sodium hydroxide solution, stirring the solution sufficiently, and then sealing and freezing the solution. After the solution is thawed, the solution is filtered, and dried to obtain modified chitosan. S2: Add the modified chitosan to the methanesulfonic acid solution, stir it thoroughly, transfer it to a container containing the phosphorous acid solution, stir it evenly, heat it, add the formaldehyde solution dropwise, condense and reflux it, after the reaction is completed, cool it, dialyze it, and distill it under reduced pressure to obtain a concentrated solution, add a mixture of anhydrous ethanol and acetone to the concentrated solution, precipitate it, let it stand, filter it, wash it, and dry it in vacuo to obtain a modified antioxidant.

7. The ultra-thin flexible hot melt adhesive film for use in bulletproof vests according to claim 6, characterized in that: In the S1, the dosage ratio of chitosan to sodium hydroxide solution is (20-30) g: (50-70) mL, the mass fraction of the sodium hydroxide solution is 50 wt %, and the treatment time is 10-12 days.

8. The ultra-thin flexible hot melt adhesive film for use in bulletproof vests according to claim 6, characterized in that: In the S2, the dosage ratio of modified chitosan, methanesulfonic acid solution, phosphorous acid solution and formaldehyde solution is (0.5-0.75) g: (150-225) mL: (6-8) mL: (6-8) mL, the mass fraction of methanesulfonic acid solution is 5wt%, the volume fraction of phosphorous acid solution is 40vt%, and the mass fraction of formaldehyde solution is 40wt%. The stirring time is 1-2h, the temperature is raised to 65-75°C, the condensation reflux reaction time is 4-8h, and the temperature is cooled to 28-32°C. During the dialysis process, the molecular weight cutoff of the dialysis bag is 12000 kDa, the dialysis time is 68-72h, the standing time is 10-12h, the vacuum drying temperature is 50-60°C, and the time is 8-12h.

9. The method for preparing an ultra-thin flexible hot melt adhesive film for use in bulletproof vests as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved: Step (1): adding ethylene-vinyl acetate copolymer and thermoplastic polyurethane elastomer into a reaction vessel equipped with an electric heating jacket and a stirrer, heating and melting and mixing uniformly to obtain a resin mixture; Step (2): Add a modified tackifier and a modified antioxidant to the resin mixture, continue stirring, then add the mixture to a casting machine, extrude, cool, wind, cut, and inspect to obtain an ultra-thin flexible hot melt adhesive film for use in bulletproof vests.

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