Polyurethane hot melt adhesive powder and preparation method and application thereof

Abstract

The present invention belongs to the technical field of hot melt adhesives, and specifically relates to a polyurethane hot melt adhesive powder and a preparation method and application thereof. The polyurethane hot melt adhesive powder provided by the present invention includes the following components in parts by weight: 35-40 parts of polyester polyol; 25-30 parts of polyether polyol; 12-15 parts of modified polyol; 30-35 parts of isocyanate; 6-8 parts of functionalized nanosilver; 3-5 parts of chain extender; 0.8-1 parts of coupling agent; 0.6-0.8 parts of antioxidant; 0.3-0.5 parts of catalyst; The present invention enhances the flame retardant and antibacterial properties of the polyurethane hot melt adhesive powder by adding functionalized nanosilver and modified polyol to the polyurethane hot melt adhesive powder components for modification. The polyurethane hot melt adhesive powder prepared by the present invention has good peel strength and mechanical properties, especially excellent flame retardant and antibacterial properties.

Description

Technical Field

[0001] The invention belongs to the technical field of hot melt adhesives, and in particular relates to polyurethane hot melt adhesive powder and a preparation method and application thereof. Background Art

[0002] White ink digital heat transfer (DTF heat transfer) is a special printing technology, which is mainly used to print the design pattern directly on the PET film, and then evenly sprinkle the hot melt powder on the pattern, melt it at high temperature and dry it, and finally cut the PET film, and use the hot press machine to attach the pattern to various types of clothing to complete the entire clothing printing process; With the rapid development of DTF heat transfer technology, the market of DTF hot melt powder has also expanded rapidly. Among them, thermoplastic polyurethane hot melt powder has become the first choice of DTF hot melt adhesive powder due to its own high peel strength, softness and elasticity, and environmental protection; Traditional polyurethane hot melt powder is usually made of components such as polyols, isocyanates and other additives, which react at a certain temperature. Some antibacterial or flame retardant products require that the printed pattern also has certain antibacterial or flame retardant properties, but using traditional polyurethane hot melt powder for DTF heat transfer cannot meet the production of functional products. Therefore, there are higher requirements for the functionality of polyurethane hot melt powder.

[0003] Chinese patent application number CN202111002271.7 discloses a halogen-containing flame retardant polyurethane hot melt adhesive and a preparation method thereof. The raw materials of the polyurethane hot melt adhesive are: polyester ether polyol, polyether polyol A, flame retardant polyether polyol, chain extender, catalyst, silane coupling agent, and diisocyanate, wherein the flame retardant polyether polyol is prepared by reacting polyoxypropylene ether diol, bromine-containing diol, double metal cyanide complex catalyst and propylene oxide as raw materials. By introducing reactive flame retardant polyether polyol and polyether polyol A containing benzene ring structure into the molecular structure of polyurethane hot melt adhesive, the flame retardant performance and temperature resistance of the hot melt adhesive are significantly improved; Chinese patent application number CN202311410950.7 discloses a flame retardant polyurethane hot melt adhesive having a flame retardant property. A flammable reactive moisture-curing polyurethane hot melt adhesive and a preparation method thereof, comprising the following components measured by weight: 10-50 parts of polyester polyol, 10-50 parts of polyether polyol, 5-10 parts of tackifying resin, 1-5 parts of flame retardant, 15-30 parts of filler and 0.1-1 part of stabilizer, wherein the flame retardant is a mixture of one or more of boron compounds, dibutylammonium phosphate, halogen flame retardant, etc., and the flame retardant performance of the polyurethane hot melt adhesive is improved by adding the flame retardant; although the above patents all add flame retardants to make the polyurethane hot melt adhesive have a certain flame retardant effect, they still cannot meet the requirements of high flame retardancy and multifunctionality. Therefore, it is necessary to develop a multifunctional polyurethane hot melt powder to meet the market demand for DTF heat transfer. Summary of the invention

[0004] The purpose of the present invention is to provide a polyurethane hot melt adhesive powder and a preparation method and application thereof in view of the deficiencies in the prior art. The present invention enhances the flame retardant and antibacterial properties of the polyurethane hot melt adhesive powder by adding functionalized nanosilver and modified polyols to the polyurethane hot melt adhesive powder components for modification. The polyurethane hot melt adhesive powder prepared by the present invention has good peel strength and mechanical properties, especially excellent flame retardant and antibacterial properties.

[0005] The technical solution adopted by the present invention to achieve the above-mentioned purpose is:

[0006] A polyurethane hot melt adhesive powder comprises the following components in parts by weight: 35-40 parts of polyester polyol; 25-30 parts of polyether polyol; 12-15 parts of modified polyol; 30-35 parts of isocyanate; 6-8 parts of functionalized nanosilver; 3-5 parts of chain extender; 0.8-1 part of coupling agent; 0.6-0.8 part of antioxidant; and 0.3-0.5 part of catalyst.

[0007] Furthermore, the polyester polyol is any one of poly(1,4-butylene adipate) glycol, poly(propylene carbonate) glycol, and polycaprolactone glycol, or a mixture of several of them.

[0008] Furthermore, the polyether polyol is any one of polytetramethylene glycol, polyoxypropylene glycol, and polyethylene glycol, or a mixture of several of them.

[0009] Furthermore, the isocyanate is any one of diphenylmethane diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate, or a mixture of several of them.

[0010] Furthermore, the chain extender is 1,4-butanediol or 1,6-hexanediol; and the coupling agent is γ-aminopropyltriethoxysilane or γ-glycidyloxypropyltrimethoxysilane.

[0011] Furthermore, the antioxidant is antioxidant 1010 or antioxidant 1076; and the catalyst is dibutyltin dilaurate or stannous octoate.

[0012] In the technical scheme of the present invention, the preparation method of the modified polyol is: adding flame retardant dimethyl hydantoin, 2-amino-1,3-propanediol and triethylamine into a reaction container containing acetonitrile, stirring evenly, and reacting at a temperature of 50-60° C. for 4-5 hours to obtain the modified polyol.

[0013] Furthermore, the molar ratio of the flame retardant dimethyl hydantoin, 2-amino-1,3-propanediol and triethylamine is 1:1.1-1.2:1.3-1.5.

[0014] In the technical solution of the present invention, the preparation method of the functionalized nanosilver is:

[0015] S1, adding γ-aminopropyltriethoxysilane to a reaction vessel containing 50-60wt% ethanol solution, stirring evenly, adjusting the pH value to 4-4.5 with dilute hydrochloric acid, adding nanosilver, stirring and reacting at a temperature of 50-60°C for 4-5h to obtain modified nanosilver;

[0016] S2. Add modified nanosilver, flame-retardant dimethylhydantoin and triethylamine into a reaction container containing ethanol, stir evenly, and react at a temperature of 60-70° C. for 5-6 hours to obtain functionalized nanosilver.

[0017] Furthermore, the mass ratio of the nano silver and γ-aminopropyltriethoxysilane in step S1 is 10:0.5-0.6; the mass ratio of the modified nano silver, flame retardant dimethyl hydantoin and triethylamine in step S2 is 1:0.3-0.4:0.08-0.1.

[0018] The preparation method of the modified polyol and the preparation method of the flame-retardant dimethyl hydantoin described in step S2 are both: firstly reacting p-chloroaniline with 5,5-dimethyl hydantoin to generate dimethyl hydantoin-aniline; then reacting dimethyl hydantoin-aniline with epichlorohydrin and 3-bromopropanol in sequence to generate hydroxylated dimethyl hydantoin; finally, reacting hydroxylated dimethyl hydantoin with diethylphosphite chloride and sodium hypochlorite in sequence to generate flame-retardant dimethyl hydantoin; specifically comprising the following steps:

[0019] First, 5,5-dimethylhydantoin and potassium hydroxide are added to a reaction container containing water and acetonitrile, stirred for 5-10 minutes, and then p-chloroaniline is added, and the reaction is carried out at a temperature of 75-80° C. for 7-8 hours to obtain dimethylhydantoin-aniline; the molar ratio of p-chloroaniline, 5,5-dimethylhydantoin and potassium hydroxide is 1:1-1.1:1.2-1.3;

[0020] Then, dimethylhydantoin-aniline is added to a reaction vessel containing chloroform, stirred evenly, and epichlorohydrin is slowly added dropwise. After the addition is completed, the reaction is carried out at a temperature of 35-40° C. for 4-5 hours, and then 3-bromopropanol and triethylamine are added. The reaction is continued for 5-6 hours at a temperature of 50-60° C. to obtain hydroxylated dimethylhydantoin; the molar ratio of the dimethylhydantoin-aniline, epichlorohydrin, 3-bromopropanol, and triethylamine is 1:1-1.1:1.1-1.2:1.3-1.5;

[0021] Finally, hydroxylated dimethyl hydantoin and triethylamine are added to a reaction vessel containing anhydrous chloroform, stirred evenly, placed in an ice bath, and diethylphosphite chloride is slowly added dropwise. After the addition is complete, the reaction is continued for 4-5 hours. The reaction is completed by TLC detection, and the temperature is naturally raised to room temperature. Sodium hypochlorite is then added and stirred for reaction for 1-2 hours to obtain flame-retardant dimethyl hydantoin; the molar ratio of the hydroxylated dimethyl hydantoin, diethylphosphite chloride, triethylamine, and sodium hypochlorite is 1:2.1-2.2:1.5-1.8:1.3-1.5.

[0022] The invention provides a method for preparing polyurethane hot melt adhesive powder. The method comprises the following steps: uniformly mixing polyester polyol, polyether polyol, modified polyol and chain extender according to weight proportion, vacuum dehydrating for 2-3 hours at a temperature of 120-130 DEG C, adding isocyanate, functionalized nano silver and catalyst under nitrogen protection, stirring and reacting for 1-1.5 hours at a temperature of 80-90 DEG C, adding coupling agent and antioxidant, continuing stirring for 0.5-1 hour, and after the reaction is completed, extruding granulation and crushing to obtain polyurethane hot melt adhesive powder.

[0023] The invention provides application of polyurethane hot melt adhesive powder in DTF heat transfer.

[0024] The present invention has the following beneficial effects:

[0025] The invention uses p-chloroaniline as a raw material, and sequentially reacts with 5,5-dimethylhydantoin, epichlorohydrin, 3-bromopropanol, diethylphosphite chloride and sodium hypochlorite to generate a flame retardant dimethylhydantoin containing a flame retardant bisphosphite group, an antibacterial chlorodimethylhydantoin group and a chlorinated hydrocarbon group in the structure; then the flame retardant dimethylhydantoin is reacted with 2-amino-1,3-propanediol to obtain a modified polyol containing a flame retardant bisphosphite group, an antibacterial chlorodimethylhydantoin group and a dihydroxyl group in the structure; in addition, the invention also uses nanoparticles to react with the modified polyol. Silver is used as a raw material, which first reacts with γ-aminopropyltriethoxysilane to introduce amino groups on the surface of nanosilver, and then reacts with the chlorinated hydrocarbon group in the flame-retardant dimethyl hydantoin to graft the flame-retardant dimethyl hydantoin onto the surface of the nanosilver to obtain functionalized nanosilver. The functionalized nanosilver and modified polyol are added to the polyurethane hot melt adhesive powder component, and both structures contain flame-retardant diphosphite groups and antibacterial chlorodimethyl hydantoin groups, which can act synergistically and greatly enhance the flame retardancy and antibacterial properties of the polyurethane hot melt adhesive powder.

[0026] In order to obtain multifunctional polyurethane hot melt adhesive powder, the present invention adds functionalized nano silver and modified polyols into the polyurethane hot melt adhesive powder components for modification, thereby enhancing the flame retardant and antibacterial properties of the polyurethane hot melt adhesive powder. The polyurethane hot melt adhesive powder prepared by the present invention has good peel strength and mechanical properties, especially excellent flame retardant and antibacterial properties, and can be applicable to the DTF heat transfer field. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; the technical features designed in different implementation modes of the present invention described below can be combined with each other as long as they do not conflict with each other; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] In the technical scheme of the present invention, the chemical reagents used are all commercially available, among which the molecular weights of polyester polyols (polybutylene adipate-1,4-diol, polypropylene carbonate diol, polycaprolactone diol) are all 1000-3000, the molecular weights of polyether polyols (polytetrahydrofuran diol, polyoxypropylene diol, polyethylene glycol) are all 1000-2000, and the molecular weights of diphenylmethane diisocyanate CAS No. 101-68- 8. Hexamethylene diisocyanate CAS No. 822-06-0, isophorone diisocyanate CAS No. 4098-71-9, 1,4-butanediol CAS No. 110-63-4, 1,6-hexanediol CAS No. 629-11-8, γ-aminopropyltriethoxysilane CAS No. 919-30-2, γ-glycidyloxypropyltrimethoxysilane CAS No. 2530-83-8, antioxidant 1010 CAS No. 6683-19-8, antioxidant 1076 CAS No. 2082-79-3, dibutyltin dilaurate CAS No. 77-58-7, stannous octoate CAS No. 301-10-0, p-aminobenzyl chloride CAS No. 65581-19-3, 5,5-dimethylhydantoin CAS No. 77-71-4, potassium hydroxide CAS No. 1310-58-3, epichlorohydrin CAS No. 106-89-8, 3-bromopropanol CAS No. 627-18-9, triethylamine CAS No. 121-44-8, diethylphosphite chloride CAS No. 589-57-1, sodium hypochlorite CAS No. 7681-52-9, 2-amino-1,3-propanediol CAS No. 534-03-2, acetonitrile CAS No. 75-05-8, chloroform CAS No. 67-66-3, ethyl acetate CAS No. 141-78-6.

[0029] Embodiment 1

[0030] The present embodiment provides a method for preparing flame-retardant dimethyl hydantoin, which comprises reacting p-chloroaniline with 5,5-dimethyl hydantoin to generate dimethyl hydantoin-aniline; then reacting dimethyl hydantoin-aniline with epichlorohydrin and 3-bromopropanol in sequence to generate hydroxylated dimethyl hydantoin; and finally reacting hydroxylated dimethyl hydantoin with diethylphosphite chloride and sodium hypochlorite in sequence to generate flame-retardant dimethyl hydantoin. The method specifically comprises the following steps:

[0031] ;

[0032] First, 19.9 g of 5,5-dimethylhydantoin and 10.3 g of potassium hydroxide were added to a reaction vessel containing 300 mL of water and 400 mL of acetonitrile, and stirred for 10 min. Then, 20.0 g of p-chloroaniline was added, and the reaction was carried out at a temperature of 75° C. for 8 h. The reaction was completed by TLC detection, and acetonitrile was removed. Ethyl acetate was added for extraction, and the organic phase was concentrated under reduced pressure to obtain 25.6 g of dimethylhydantoin-aniline; wherein the molar ratio of p-chloroaniline, 5,5-dimethylhydantoin and potassium hydroxide was 1:1.05:1.3; dimethylhydantoin-aniline: ESI (m / z): 220.2 [M+H] + , 1 H-NMR (600 MHz, DMSO-d 6 , δppm): 10.86 (s, 1H), 7.12 (d, J=8.4Hz, 2H), 6.22 (d, J=8.4Hz, 2H), 4.52 (s, 2H), 1.48 (s, 6H).

[0033] ;

[0034] Then, 25.0 g of dimethyl hydantoin-aniline was added to a reaction vessel containing 600 mL of chloroform, stirred evenly, and 11.1 g of epichlorohydrin was slowly added dropwise. After the addition was completed, the mixture was reacted at 40° C. for 4 h. Then, 17.4 g of 3-bromopropanol and 15.0 g of triethylamine were added. The mixture was reacted at 60° C. for 5 h. The reaction was completed by TLC detection. The chloroform was removed, and water and ethyl acetate were added for extraction. The organic phase was concentrated under reduced pressure to obtain hydroxylated dimethyl hydantoin; wherein the molar ratio of dimethyl hydantoin-aniline, epichlorohydrin, 3-bromopropanol, and triethylamine was 1:1.05:1.1:1.3; hydroxylated dimethyl hydantoin: ESI (m / z): 370.9 [M+H] + , 1 H-NMR (600 MHz, DMSO-d 6, δppm): 10.84 (s, 1H), 7.09 (d, J=8.4Hz, 2H), 6.90 (d, J=8.4Hz, 2H), 5.37 (s, 1H), 4.43 (s, 1H ), 3.86-3.90 (m, 1H), 3.52-3.63 (m, 4H), 3.33-3.38 (m, 4H), 1.72-1.79 (m, 2H), 1.49 (s, 6H).

[0035] ;

[0036] Finally, 29.0 g of hydroxylated dimethyl hydantoin and 11.9 g of triethylamine were added to a reaction vessel containing 400 mL of anhydrous chloroform, stirred evenly, placed in an ice bath, and 25.8 g of diethylphosphite chloride was slowly added dropwise. After the addition was completed, the reaction was continued for 5 h. The reaction was completed by TLC detection. The temperature was naturally raised to room temperature, and 7.6 g of sodium hypochlorite was added. The reaction was stirred for 1 h, chloroform was removed, water and ethyl acetate were added for extraction, and the organic phase was concentrated under reduced pressure to obtain 41.5 g of flame-retardant dimethyl hydantoin; wherein the molar ratio of hydroxylated dimethyl hydantoin, diethylphosphite chloride, triethylamine, and sodium hypochlorite was 1:2.1:1.5:1.3; flame-retardant dimethyl hydantoin: ESI (m / z): 645.5 [M+H] + , 1 H-NMR (600 MHz, DMSO-d 6 , δppm): 7.10 (d, J=8.4Hz, 2H), 6.91 (d, J=8.4Hz, 2H), 3.80-3.90 (m, 11H), 3 .60-3.65 (m, 2H), 3.32-3.38 (m, 4H), 1.71-1.78 (m, 8H), 1.25-1.30 (m, 12H).

[0037] Embodiment 2

[0038] This embodiment provides a method for preparing a modified polyol:

[0039] ;

[0040] 20.0 g of flame retardant dimethyl hydantoin, 3.1 g of 2-amino-1,3-propanediol and 4.1 g of triethylamine were added to a reaction vessel containing 200 mL of acetonitrile, stirred evenly, and reacted at a temperature of 55°C for 5 h. The reaction was completed by TLC detection, and acetonitrile was removed. Water and ethyl acetate were added for extraction. The organic phase was concentrated under reduced pressure to obtain 18.7 g of modified polyol; wherein the molar ratio of flame retardant dimethyl hydantoin, 2-amino-1,3-propanediol and triethylamine was 1:1.1:1.3; modified polyol: ESI (m / z): 700.1 [M+H] + ,1 H-NMR (600 MHz, DMSO-d 6 , δppm): 7.72 (s, 1H), 7.08 (d, J=8.4Hz, 2H), 6.90 (d, J=8.4Hz, 2H), 4.49 (s, 2H), 3.80-3.89 (m, 10H), 3.50-3 .61 (m, 6H), 3.33-3.38 (m, 3H), 2.81-2.88 (m, 1H), 2.56-2.62 (m, 2H), 1.72-1.78 (m, 8H), 1.26-1.30 (m, 12H).

[0041] Embodiment 3

[0042] A polyurethane hot melt adhesive powder comprises the following components in parts by weight: 40 parts of polyester polyol; 28 parts of polyether polyol; 15 parts of modified polyol; 35 parts of isocyanate; 8 parts of functionalized nano silver; 5 parts of chain extender; 1 part of coupling agent; 0.7 parts of antioxidant; and 0.5 parts of catalyst.

[0043] The polyester polyol is poly(1,4-butylene adipate) diol; the polyether polyol is polytetramethylene glycol; the isocyanate is diphenylmethane diisocyanate; the chain extender is 1,4-butanediol; the coupling agent is γ-aminopropyltriethoxysilane; the antioxidant is antioxidant 1010; and the catalyst is dibutyltin dilaurate.

[0044] The preparation method of functionalized nanosilver is as follows:

[0045] S1. Add γ-aminopropyltriethoxysilane to a reaction vessel containing 60wt% ethanol solution, stir evenly, adjust the pH value to 4.5 with dilute hydrochloric acid, add nanosilver, and react with stirring at 60°C for 4h to obtain modified nanosilver; wherein the mass ratio of nanosilver to γ-aminopropyltriethoxysilane is 10:0.6; the amount of 60wt% ethanol solution is 10 times the mass of nanosilver; and the concentration of dilute hydrochloric acid is 1mol / L;

[0046] S2. Add modified nanosilver, flame retardant dimethylhydantoin and triethylamine into a reaction vessel containing ethanol, stir evenly, and react at 60°C for 6 hours to obtain functionalized nanosilver; wherein the mass ratio of modified nanosilver, flame retardant dimethylhydantoin and triethylamine is 1:0.4:0.1; and the amount of ethanol used is 10 times the mass of the modified nanosilver.

[0047] A preparation method of polyurethane hot melt adhesive powder, comprising the following steps: According to the weight ratio, mix polyester polyol, polyether polyol, modified polyol, and chain extender evenly, dehydrate under vacuum at a temperature of 130 °C for 2 h, under nitrogen protection, add isocyanate, functionalized nano-silver, and catalyst, stir and react at a temperature of 90 °C for 1 h, then add coupling agent and antioxidant, continue to stir for 0.8 h, after the reaction is completed, extrude and granulate, and crush to obtain polyurethane hot melt adhesive powder.

[0048] Example 4

[0049] A polyurethane hot melt adhesive powder, which comprises the following components in parts by weight: 38 parts of polyester polyol; 30 parts of polyether polyol; 13 parts of modified polyol; 33 parts of isocyanate; 7 parts of functionalized nano-silver; 4 parts of chain extender; 0.8 part of coupling agent; 0.8 part of antioxidant; 0.4 part of catalyst.

[0050] The polyester polyol is poly(propylene carbonate) diol; the polyether polyol is poly(propylene oxide) diol; the isocyanate is isophorone diisocyanate; the chain extender is 1,6-hexanediol; the coupling agent is γ-glycidoxypropyltrimethoxysilane; the antioxidant is antioxidant 1076; the catalyst is stannous octoate.

[0051] The preparation method of the functionalized nano-silver is as follows:

[0052] S1. Add γ-aminopropyltriethoxysilane to a reaction vessel containing a 50 wt% ethanol solution, stir evenly, adjust the pH value to 4 using dilute hydrochloric acid, add nano-silver, and stir and react at a temperature of 50 °C for 5 h to obtain modified nano-silver; the mass ratio of nano-silver to γ-aminopropyltriethoxysilane is 10:0.5; the dosage of the 50 wt% ethanol solution is 10 times the mass of nano-silver; the concentration of the dilute hydrochloric acid is 1 mol / L;

[0053] S2. Add the modified nano-silver, flame-retardant dimethylhydantoin, and triethylamine to a reaction vessel containing ethanol, stir evenly, and stir and react at a temperature of 70 °C for 5 h to obtain functionalized nano-silver; the mass ratio of the modified nano-silver, flame-retardant dimethylhydantoin, and triethylamine is 1:0.3:0.08; the dosage of ethanol is 10 times the mass of the modified nano-silver.

[0054] A preparation method of polyurethane hot melt adhesive powder, comprising the following steps: According to the weight ratio, mix polyester polyol, polyether polyol, modified polyol, and chain extender evenly, dehydrate under vacuum at a temperature of 120 °C for 3 h, under nitrogen protection, add isocyanate, functionalized nano-silver, and catalyst, stir and react at a temperature of 80 °C for 1.5 h, then add coupling agent and antioxidant, continue to stir for 1 h, after the reaction is completed, extrude and granulate, and crush to obtain polyurethane hot melt adhesive powder.

[0055] Embodiment 5

[0056] A polyurethane hot melt adhesive powder comprises the following components in parts by weight: 35 parts of polyester polyol; 25 parts of polyether polyol; 12 parts of modified polyol; 30 parts of isocyanate; 6 parts of functionalized nano silver; 3 parts of chain extender; 0.9 parts of coupling agent; 0.6 parts of antioxidant; and 0.3 parts of catalyst.

[0057] The polyester polyol is polycaprolactone diol; the polyether polyol is polyethylene glycol; the isocyanate is hexamethylene diisocyanate; the chain extender is 1,6-hexanediol; the coupling agent is γ-aminopropyltriethoxysilane; the antioxidant is antioxidant 1076; and the catalyst is dibutyltin dilaurate.

[0058] The preparation method of functionalized nanosilver is as follows:

[0059] S1. Add γ-aminopropyltriethoxysilane to a reaction vessel containing 55wt% ethanol solution, stir evenly, adjust the pH value to 4.2 with dilute hydrochloric acid, add nanosilver, and react with stirring at a temperature of 55°C for 4.5h to obtain modified nanosilver; wherein the mass ratio of nanosilver to γ-aminopropyltriethoxysilane is 10:0.55; the amount of 55wt% ethanol solution is 10 times the mass of nanosilver; and the concentration of dilute hydrochloric acid is 1mol / L;

[0060] S2. Add modified nanosilver, flame retardant dimethylhydantoin and triethylamine into a reaction vessel containing ethanol, stir evenly, and react at a temperature of 65°C for 5.5 hours to obtain functionalized nanosilver; wherein the mass ratio of modified nanosilver, flame retardant dimethylhydantoin and triethylamine is 1:0.35:0.09; and the amount of ethanol used is 10 times the mass of the modified nanosilver.

[0061] A preparation method of polyurethane hot melt adhesive powder comprises the following steps: uniformly mixing polyester polyol, polyether polyol, modified polyol and chain extender according to weight ratio, vacuum dehydrating at 125°C for 2.5 hours, adding isocyanate, functionalized nano silver and catalyst under nitrogen protection, stirring and reacting at 85°C for 1.2 hours, adding coupling agent and antioxidant, continuing stirring for 0.5 hours, and after the reaction is completed, extruding granulation and crushing to obtain polyurethane hot melt adhesive powder.

[0062] Comparative Example 1

[0063] Compared with Example 3, the functionalized nanosilver in the polyurethane hot melt adhesive powder component is replaced with modified nanosilver.

[0064] A polyurethane hot melt adhesive powder comprises the following components in parts by weight: 40 parts of polyester polyol; 28 parts of polyether polyol; 15 parts of modified polyol; 35 parts of isocyanate; 8 parts of modified nano silver; 5 parts of chain extender; 1 part of coupling agent; 0.7 parts of antioxidant; and 0.5 parts of catalyst.

[0065] The polyester polyol is poly(1,4-butylene adipate) diol; the polyether polyol is polytetramethylene glycol; the isocyanate is diphenylmethane diisocyanate; the chain extender is 1,4-butanediol; the coupling agent is γ-aminopropyltriethoxysilane; the antioxidant is antioxidant 1010; and the catalyst is dibutyltin dilaurate.

[0066] The preparation method of modified nanosilver is the same as step S1 in Example 3.

[0067] The preparation method of a polyurethane hot melt adhesive powder is the same as that of Example 3.

[0068] Comparative Example 2

[0069] Compared with Example 3, the modified polyol in the polyurethane hot melt adhesive powder component is replaced with 2-amino-1,3-propanediol.

[0070] A polyurethane hot melt adhesive powder comprises the following components in parts by weight: 40 parts of polyester polyol; 28 parts of polyether polyol; 15 parts of 2-amino-1,3-propylene glycol; 35 parts of isocyanate; 8 parts of functionalized nano silver; 5 parts of chain extender; 1 part of coupling agent; 0.7 parts of antioxidant; and 0.5 parts of catalyst.

[0071] The polyester polyol is poly(1,4-butylene adipate) diol; the polyether polyol is polytetramethylene glycol; the isocyanate is diphenylmethane diisocyanate; the chain extender is 1,4-butanediol; the coupling agent is γ-aminopropyltriethoxysilane; the antioxidant is antioxidant 1010; and the catalyst is dibutyltin dilaurate.

[0072] The preparation method of functionalized nano silver and polyurethane hot melt adhesive powder is the same as that in Example 3.

[0073] Comparative Example 3

[0074] Compared with Example 3, the functionalized nanosilver in the polyurethane hot melt adhesive powder component is replaced by modified nanosilver, and the modified polyol is replaced by 2-amino-1,3-propanediol.

[0075] A polyurethane hot melt adhesive powder comprises the following components in parts by weight: 40 parts of polyester polyol; 28 parts of polyether polyol; 15 parts of 2-amino-1,3-propylene glycol; 35 parts of isocyanate; 8 parts of modified nano silver; 5 parts of chain extender; 1 part of coupling agent; 0.7 parts of antioxidant; and 0.5 parts of catalyst.

[0076] The polyester polyol is poly(1,4-butylene adipate) diol; the polyether polyol is polytetramethylene glycol; the isocyanate is diphenylmethane diisocyanate; the chain extender is 1,4-butanediol; the coupling agent is γ-aminopropyltriethoxysilane; the antioxidant is antioxidant 1010; and the catalyst is dibutyltin dilaurate.

[0077] The preparation method of a polyurethane hot melt adhesive powder is the same as that of Example 3.

[0078] Performance Testing

[0079] The performance tests were conducted on the polyurethane hot melt adhesive powders prepared in Examples 3 to 5 and Comparative Examples 1 to 3, wherein the viscosity was in accordance with the HG / T 3660-1999 standard; the peel strength was in accordance with the GB / T 2790-1995 standard, and the peel strength of the polyester cloth was tested by a tensile testing machine; the tensile strength was in accordance with the GB / T 7124-2008 standard; the elongation at break was in accordance with the GB / T 1040.3-2006 standard; the limiting oxygen index was in accordance with the GB / T 2406-2009 standard; the antibacterial property was tested by the inhibition zone method, and the test bacteria were Staphylococcus aureus (ATCC6538) and Escherichia coli (ATCC8739). The test sample was a polyurethane hot melt adhesive powder cured adhesive layer disc (diameter 5 mm, thickness 1 mm), and 200 μL of activated bacterial solution (the same amount of concentration was 10 6 cfu / mL of Staphylococcus aureus suspension and Escherichia coli suspension), the gelatin disc was placed in the center of the culture dish, cultured in a cell culture incubator at 37°C for 24 hours, and the diameter of the inhibition zone was measured; the test results are shown in Table 1 below.

[0080] Table 1 Performance test results

[0081]

[0082] From the results in Table 1, it can be seen that the viscosity, peel strength, tensile strength, elongation at break, limiting oxygen index and inhibition zone diameter of the polyurethane hot melt adhesive powder of Examples 3 to 5 are significantly higher than those of Comparative Examples 1 to 3, indicating that the polyurethane hot melt adhesive powder prepared by the present invention has good peel strength and mechanical properties, especially excellent flame retardant and antibacterial properties; compared with Comparative Examples 1 to 3, the polyurethane hot melt adhesive powder of the present invention adds functionalized nanosilver and modified polyols, wherein the functionalized nanosilver is grafted with flame retardant bisphosphite groups and antibacterial chlorodimethylhydantoin groups on the surface, and thus has good flame retardant and antibacterial effects; the modified polyol also contains flame retardant bisphosphite groups and antibacterial chlorodimethylhydantoin groups, which can introduce these groups into the polyurethane molecular structure during the reaction process, and synergize with the functionalized nanosilver, thereby greatly enhancing the flame retardant and antibacterial properties of the polyurethane hot melt adhesive powder.

[0083] It should be noted that, in this article, terms such as "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0084] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A polyurethane hot melt adhesive powder, characterized in that: The polyurethane hot melt adhesive powder comprises the following components by weight: 35-40 parts of polyester polyol; 25-30 parts of polyether polyol; 12-15 parts of modified polyol; 30-35 parts of isocyanate; 6-8 parts of functionalized nanosilver; 3-5 parts of chain extender; 0.8-1 parts of coupling agent; 0.6-0.8 parts of antioxidant; 0.3-0.5 parts of catalyst; The preparation method of the modified polyol is as follows: adding flame-retardant dimethyl hydantoin, 2-amino-1,3-propanediol and triethylamine into a reaction container containing acetonitrile, stirring evenly, and reacting at a temperature of 50-60° C. for 4-5 hours to obtain the modified polyol; The preparation method of the functionalized nanosilver is as follows: S1, adding γ-aminopropyltriethoxysilane to a reaction vessel containing 50-60wt% ethanol solution, stirring evenly, adjusting the pH value to 4-4.5 with dilute hydrochloric acid, adding nanosilver, stirring and reacting at a temperature of 50-60°C for 4-5h to obtain modified nanosilver; S2, adding modified nanosilver, flame retardant dimethylhydantoin and triethylamine into a reaction vessel containing ethanol, stirring evenly, and reacting at a temperature of 60-70° C. for 5-6 hours to obtain functionalized nanosilver; The preparation method of the modified polyol and the preparation method of the flame-retardant dimethyl hydantoin described in step S2 are both: firstly reacting p-chloroaniline with 5,5-dimethyl hydantoin to generate dimethyl hydantoin-aniline; then reacting dimethyl hydantoin-aniline with epichlorohydrin and 3-bromopropanol in sequence to generate hydroxylated dimethyl hydantoin; finally, reacting hydroxylated dimethyl hydantoin with diethylphosphite chloride and sodium hypochlorite in sequence to generate flame-retardant dimethyl hydantoin; the chemical structure of the flame-retardant dimethyl hydantoin is: 。 2. The polyurethane hot melt adhesive powder according to claim 1, characterized in that: In the preparation method of the modified polyol, the molar ratio of the flame retardant dimethyl hydantoin, 2-amino-1,3-propanediol and triethylamine is 1:1.1-1.2:1.3-1.

5.

3. The polyurethane hot melt adhesive powder according to claim 1, characterized in that: The mass ratio of the nano silver and γ-aminopropyltriethoxysilane in step S1 is 10:0.5-0.6; the mass ratio of the modified nano silver, flame retardant dimethyl hydantoin and triethylamine in step S2 is 1:0.3-0.4:0.08-0.

1.

4. The polyurethane hot melt adhesive powder according to claim 1, characterized in that: The polyester polyol is any one of poly(1,4-butylene adipate) diol, poly(propylene carbonate) diol and poly(caprolactone) diol or a mixture of several of them.

5. The polyurethane hot melt adhesive powder according to claim 1, characterized in that: The polyether polyol is any one of polytetrahydrofuran diol, polyoxypropylene diol and polyethylene glycol or a mixture of several of them.

6. The polyurethane hot melt adhesive powder according to claim 1, characterized in that: The isocyanate is any one of diphenylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate or a mixture of several of them.

7. The polyurethane hot melt adhesive powder according to claim 1, characterized in that: The chain extender is 1,4-butanediol or 1,6-hexanediol; the coupling agent is γ-aminopropyltriethoxysilane or γ-glycidyloxypropyltrimethoxysilane.

8. The polyurethane hot melt adhesive powder according to claim 1, characterized in that: The antioxidant is antioxidant 1010 or antioxidant 1076; the catalyst is dibutyltin dilaurate or stannous octoate.

9. A method for preparing the polyurethane hot melt adhesive powder according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: uniformly mixing polyester polyol, polyether polyol, modified polyol and chain extender according to weight proportion, vacuum dehydrating for 2-3 hours at a temperature of 120-130 DEG C, adding isocyanate, functionalized nano silver and catalyst under nitrogen protection, stirring and reacting for 1-1.5 hours at a temperature of 80-90 DEG C, adding coupling agent and antioxidant, continuing stirring for 0.5-1 hour, and after the reaction is completed, extruding granulation and crushing to obtain polyurethane hot melt adhesive powder.

10. Use of the polyurethane hot melt adhesive powder according to any one of claims 1 to 8 in DTF heat transfer.

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