A polyurethane hot melt adhesive composition and its application

Abstract

The present invention belongs to the technical field of hot melt adhesives, and specifically relates to a polyurethane hot melt adhesive composition and its application. The polyurethane hot melt adhesive composition includes the following components by weight: 40-50 parts of polyester polyol; 20-25 parts of bio-based polyether polyol; 25-30 parts of bio-based isocyanate; 15-20 parts of functionalized polydopamine; 5-10 parts of filler; 0.5-0.8 parts of catalyst; 0.5-1 parts of coupling agent; 1-3 parts of chain extender; Bio-based polyether polyol and bio-based isocyanate are added to the components of the polyurethane hot melt adhesive composition provided by the present invention, and the environmental protection performance is better. The polyurethane hot melt adhesive is modified by adding functionalized polydopamine to obtain a polyurethane hot melt adhesive composition with good adhesion, mechanical properties, waterproofness, flame retardancy and antibacterial properties, which is suitable for use in different fields.

Description

Technical Field

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

[0002] Hot melt adhesive is an adhesive whose physical state changes with temperature within a certain temperature range, but whose chemical properties remain unchanged. Hot melt adhesive has various forms, including hot melt adhesive blocks, hot melt adhesive particles, hot melt adhesive strips, hot melt adhesive powder, hot melt adhesive film, hot melt adhesive sheet, etc. According to the different synthetic raw materials, hot melt adhesive is mainly divided into polyurethane hot melt adhesive, ethylene-vinyl acetate copolymer (EVA) hot melt adhesive, polyolefin hot melt adhesive, etc. Among them, polyurethane hot melt adhesive has the advantages of excellent adhesion, flexibility, low temperature resistance, wear resistance, etc., and is widely used in textile collars, packaging, and construction. , automobile, electronics and other fields. Since polyester polyurethane contains ester groups with strong polarity, it is easy to crystallize and has excellent heat resistance and adhesion properties. Polyether polyurethane contains flexible ether bonds, is not easy to hydrolyze and has good water resistance. The two are usually mixed to obtain polyurethane hot melt adhesive with excellent comprehensive performance. The synthetic raw materials of traditional polyurethane hot melt adhesive mostly come from non-renewable petroleum-based raw materials, which is not conducive to the sustainable development of resources. Bio-based polyurethane hot melt adhesive with better environmental performance is gradually replacing traditional polyurethane hot melt adhesive and becoming a new research hotspot.

[0003] A Chinese patent with application number CN202211131650.0 discloses a method for preparing a heat-resistant biomass-based polyurethane hot melt adhesive and its application. First, polyester polyol, diphenylmethane diisocyanate, and modified lignin are reacted under the action of dibutyltin dilaurate to obtain biomass-based polyurethane, and then the biomass-based polyurethane, terpene resin, ethylene-vinyl acetate copolymer resin, defoamer, and plasticizer are compounded to obtain a heat-resistant biomass-based polyurethane hot melt adhesive, wherein the modified lignin is obtained by an imidization reaction of a novel bis(anhydride phenyl ester) DOPO compound and amino lignin. The heat resistance of the polyurethane hot melt adhesive is enhanced by grafting the DOPO structure and the imide ring structure into the polyurethane main chain. However, the bis(anhydride phenyl ester) DOPO compound contains a large amount of rigid benzene ring structure, which reduces the flexibility of the polyurethane hot melt adhesive.

[0004] A Chinese patent application with application number CN202410543799.2 discloses a bio-based polyurethane hot melt adhesive and a preparation method thereof. The raw materials include, by mass, 40-60 parts of bio-based polyester polyol, 15-25 parts of bio-based polyether polyol, 20-30 parts of bio-based isocyanate, 10-20 parts of filler, 1-2 parts of silane coupling agent, 0.1-0.3 parts of catalyst, 2-6 parts of viscosity regulator, 1.5-4.5 parts of antioxidant, 1-3 parts of plasticizer, 1-3 parts of tackifier, and 0.5-1.5 parts of chain extender. The synthetic raw materials of the bio-based polyurethane hot melt adhesive are all bio-based raw materials with excellent environmental protection performance. The anti-aging performance of the hot melt adhesive is improved by designing an anti-aging agent composed of antioxidants, light stabilizers and heat stabilizers. However, the bio-based polyurethane hot melt adhesive has deficiencies in flexibility, bonding strength and other aspects.

[0005] Therefore, it is necessary to develop a bio-based hot melt adhesive with excellent comprehensive performance to meet market demand. Summary of the invention

[0006] The purpose of the present invention is to provide a polyurethane hot melt adhesive composition and its application in view of the deficiencies in the prior art. Bio-based polyether polyols and bio-based isocyanates are added to the components of the polyurethane hot melt adhesive composition, which has better environmental performance. The polyurethane hot melt adhesive is modified by adding functionalized polydopamine to obtain a polyurethane hot melt adhesive composition with good adhesion, mechanical properties, waterproofness, flame retardancy and antibacterial properties, which is suitable for use in different fields.

[0007] The technical solution adopted by the present invention to achieve the above-mentioned purpose is:

[0008] A polyurethane hot melt adhesive composition comprises the following components in parts by weight: 40-50 parts of polyester polyol; 20-25 parts of bio-based polyether polyol; 25-30 parts of bio-based isocyanate; 15-20 parts of functionalized polydopamine; 5-10 parts of filler; 0.5-0.8 parts of catalyst; 0.5-1 parts of coupling agent; and 1-3 parts of chain extender.

[0009] Furthermore, the polyester polyol is any one of poly(1,4-butylene adipate diol), poly(caprolactone diol) and poly(hexane adipate diol) or a mixture of several of them.

[0010] Furthermore, the bio-based polyether polyol is polytrimethylene ether glycol; the bio-based isocyanate is any one of diphenylmethane diisocyanate, 1,5-pentane diisocyanate, and dicyclohexylmethane diisocyanate, or a mixture of several thereof.

[0011] Furthermore, the filler is any one of talc, calcium carbonate, titanium dioxide or a mixture of the two or more thereof; and the catalyst is dibutyltin dilaurate or dibutyltin dioctoate.

[0012] Furthermore, the coupling agent is any one of anilinemethyl triethoxysilane, vinyl triethoxysilane, γ-aminopropyl triethoxysilane, or a mixture of several of them; the chain extender is any one of 1,4-butanediol, 1,2-propylene glycol, and 1,6-hexanediol, or a mixture of several of them.

[0013] In the technical solution of the present invention, the preparation method of the functionalized polydopamine is:

[0014] (1) Add dopamine hydrochloride to a reaction vessel containing Tris-HCl buffer, stir evenly, adjust the pH value to 8.5-8.6 with an alkaline solution, react for 20-22 hours at room temperature, and after the reaction is completed, centrifuge, wash the product with water, and dry it to obtain polydopamine;

[0015] (2) Add polydopamine, a functional modifier and triethylamine to a reaction vessel containing a solvent, stir evenly, and react at a temperature of 50-60° C. for 4-5 hours. After the reaction is completed, centrifuge, wash the product with water, and dry it to obtain functionalized polydopamine.

[0016] Furthermore, in step (1), the content of dopamine hydrochloride in each milliliter of Tris-HCl buffer is 3-4 mg; and the alkaline solution is a 20-30 wt % sodium hydroxide or potassium hydroxide solution.

[0017] Furthermore, the solvent in step (2) is a 50-60% ethanol solution; the mass ratio of the polydopamine, the functional modifier, the triethylamine, and the solvent is 10:2-3:0.3-0.5:150-200.

[0018] In the technical solution of the present invention, the functional modifier is prepared by sequentially reacting 4-chlorophenethylamine with dodecyldimethyl tertiary amine, epichlorohydrin, diethylphosphite chloride, and 2,6-difluorobenzyl chloride; the preparation method of the functional modifier is:

[0019] S1. Add 4-chlorophenylethylamine and dodecyldimethyl tertiary amine to a reaction vessel containing ethanol, stir evenly, and reflux at 80° C. for 10-11 hours to obtain intermediate 1;

[0020] S2, add intermediate 1 to a reaction vessel containing anhydrous chloroform, stir evenly, slowly drop epichlorohydrin, after the dropwise addition is complete, stir and react for 4-5 hours at a temperature of 35-40°C, then place the reaction vessel in an ice bath, add triethylamine, stir evenly, drop diethylphosphite chloride, after the dropwise addition is complete, continue to react for 3-4 hours under ice bath conditions to obtain intermediate 2;

[0021] S3. Add intermediate 2, 2,6-difluorobenzyl chloride, potassium iodide and potassium carbonate to a reaction vessel containing N,N-dimethylformamide, stir evenly, and react for 5-6 hours at room temperature to obtain a functional modifier.

[0022] Furthermore, the molar ratio of 4-chlorophenylethylamine and dodecyldimethyl tertiary amine in step S1 is 1:1.1-1.2; the molar ratio of intermediate 1, epichlorohydrin, diethylphosphite chloride and triethylamine in step S2 is 1:1-1.1:1.1-1.2:1.3-1.5; the molar ratio of intermediate 2, 2,6-difluorobenzyl chloride, potassium iodide and potassium carbonate in step S3 is 1:1.1-1.2:1.1-1.2:1.3-1.4.

[0023] The invention provides an application of a polyurethane hot melt adhesive composition in the fields of packaging, automobile industry and construction.

[0024] The present invention also provides a method for preparing a polyurethane hot melt adhesive composition, comprising the following steps:

[0025] Step 1: Add polyester polyol, bio-based polyether polyol and functionalized polydopamine into a reaction container according to weight ratio, heat to 120-130° C., and dehydrate for 1.5-2 hours under vacuum to obtain a mixture;

[0026] Step 2: Cool the mixture to 70°C, add bio-based isocyanate and catalyst under nitrogen protection, heat to 80-90°C, stir for 1.5-2h, add filler, coupling agent and chain extender, continue stirring for 1-1.5h to obtain a hot melt adhesive composition.

[0027] The present invention has the following beneficial effects:

[0028] The invention uses dopamine hydrochloride as a raw material, first polymerizes to form polydopamine, and then utilizes the amino group in the polydopamine to react with the chlorinated hydrocarbon group in the functional modifier, and grafts the functional modifier containing an antibacterial long-chain quaternary ammonium salt group, a hydrophobic difluorophenyl group, and a flame retardant phosphite group into the polydopamine to obtain functionalized polydopamine; the invention adds the functionalized polydopamine into the polyurethane hot melt adhesive composition, and the rigid benzene ring structure contained in the functionalized polydopamine ensures the strength of the polyurethane hot melt adhesive, while the flexible dodecyl long-chain quaternary ammonium salt group can also give the polyurethane hot melt adhesive good flexibility; the polydopamine structure containing the catechol group itself has good bonding performance and antibacterial effect, can participate in the synthesis of polyurethane, and is helpful to improve the bonding performance of the polyurethane hot melt adhesive; the functional modifier grafted into the functionalized polydopamine can also further enhance the antibacterial, flame retardant and waterproof properties of the polyurethane hot melt adhesive.

[0029] Compared with traditional polyurethane hot melt adhesives, the polyurethane hot melt adhesive composition provided by the present invention has better environmental protection performance by adding bio-based polyether polyols and bio-based isocyanates to the components. The polyurethane hot melt adhesive is modified by adding functionalized polydopamine to obtain a polyurethane hot melt adhesive composition with good adhesion, mechanical properties, waterproofness, flame retardancy and antibacterial properties, which is suitable for use in different fields. DETAILED DESCRIPTION

[0030] 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 application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, 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.

[0031] In the technical solution of the present invention, the chemical reagents used are all commercially available, including 1,4-butanediol CAS No. 110-63-4, 1,2-propylene glycol CAS No. 57-55-6, 1,6-hexanediol CAS No. 629-11-8, dopamine hydrochloride CAS No. 62-31-7, sodium hydroxide CAS No. 1310-73-2, potassium hydroxide CAS No. 1310-58-3, 4-chlorophenylethylamine CAS No. 156-41-2; dodecyl dimethyl tertiary amine CAS No. 112-18-5; 2,6-dimethoxy-1,4-diol CAS No. 110-63-4; 1,2 ... Fluorobenzyl chloride CAS No. 697-73-4, potassium iodide CAS No. 7681-11-0, potassium carbonate CAS No. 584-08-7, epichlorohydrin CAS No. 106-89-8; diethylphosphite chloride CAS No. 589-57-1; triethylamine CAS No. 121-44-8, ethanol CAS No. 64-17-5, chloroform CAS No. 67-66-3, ether CAS No. 60-29-7, N,N-dimethylformamide CAS No. 68-12-2, ethyl acetate CAS No. 141-78-6.

[0032] Embodiment 1

[0033] This embodiment provides a method for preparing a functional modifier.

[0034] The synthetic route of intermediate 1 is:

[0035] ;

[0036] S1. Add 4-chlorophenethylamine and dodecyldimethylamine to a reaction vessel containing 500 mL of ethanol, stir evenly, reflux at 80° C. for 11 h, detect the completion of the reaction by TLC, remove ethanol, add 50 mL of ether, stir for 30 min, filter, wash the filter residue with ether, and dry to obtain the intermediate 1, wherein the molar ratio of 4-chlorophenethylamine to dodecyldimethylamine is 1:1.1;

[0037] Intermediate 1: ESI (m / z): 370.0 [M+H] + , 1 H-NMR (600 MHz, DMSO-d 6 , δppm): 7.22 (d, J=8.6Hz, 2H), 7.04 (d, J=8.6Hz, 2H), 3.72 (s, 6H), 3.05-3.15 (m, 4H), 2. 83-2.90 (m, 2H), 1.71-1.79 (m, 2H), 1.60 (s, 2H), 1.26-1.32 (m, 18H), 0.88-0.93 (m, 3H).

[0038] The synthetic route of intermediate 2 is:

[0039] ;

[0040] S2, add 31.0g intermediate 1 to a reaction vessel containing 500mL anhydrous chloroform, stir evenly, slowly add 8.2g epichlorohydrin dropwise, after the addition is complete, stir the reaction at a temperature of 40°C for 5h, then place the reaction vessel in an ice bath, add 11.1g triethylamine, stir evenly, add 14.5g diethylphosphite chloride dropwise, after the addition is complete, continue to react for 4h under ice bath conditions, TLC detection reaction is complete, remove anhydrous chloroform, add 60mL ether, stir for 30min, filter, wash the filter residue with ether, and dry to obtain 35.2g intermediate 2, the molar ratio of intermediate 1, epichlorohydrin, diethylphosphite chloride, and triethylamine is 1:1.05:1.1:1.3;

[0041] Intermediate 2: ESI (m / z): 582.6 [M+H] + , 1 H-NMR (600 MHz, DMSO-d 6 , δppm): 7.20 (d, J=8.6Hz, 2H), 7.03 (d, J=8.6Hz, 2H), 3.85-3.91 (m, 5H), 3.63-3.72 (m, 8H), 3.35-3.38 (m, 1H), 3. 21-3.26 (m, 2H), 2.71-2.88 (m, 5H), 2.51-2.57 (m, 1H), 1.72-1.79 (m, 2H), 1.24-1.32 (m, 24H), 0.89-0.92 (m, 3H).

[0042] The synthetic route of the functional modifier is:

[0043] ;

[0044] S3, to a reaction vessel containing 500 mL of N,N-dimethylformamide, add 35.0 g of intermediate 2, 10.8 g of 2,6-difluorobenzyl chloride, 11.0 g of potassium iodide, and 10.8 g of potassium carbonate, stir evenly, react at room temperature for 6 h, TLC detection shows that the reaction is complete, add water and ethyl acetate for extraction, and concentrate the aqueous phase under reduced pressure to obtain 36.1 g of a functional modifier; the molar ratio of intermediate 2, 2,6-difluorobenzyl chloride, potassium iodide, and potassium carbonate is 1:1.1:1.1:1.3;

[0045] Functional modifier: ESI (m / z): 708.8 [M+H] + , 1 H-NMR (600 MHz, DMSO-d 6, δppm): 7.74 (t, J=8.7Hz, 1H), 7.40 (d, J=8.5Hz, 2H), 7.21 (d, J=8.6Hz, 2H), 7.02 (d, J=8.6Hz, 2H), 3.84-3.89 (m, 5H), 3.72 (s, 6H), 3.61-3.65 (m, 3H), 3.35-3.39 (m, 1H), 3.22-3.29 (m, 2H), 2.60-2.69 (m, 5H), 2.35- 2.39 (m, 1H), 1.72-1.78 (m, 2H), 1.25-1.32 (m, 24H), 0.88-0.92 (m, 3H).

[0046] Embodiment 2

[0047] A polyurethane hot melt adhesive composition comprises the following components in parts by weight: 45 parts of polyester polyol; 25 parts of bio-based polyether polyol; 30 parts of bio-based isocyanate; 20 parts of functionalized polydopamine; 10 parts of filler; 0.8 parts of catalyst; 1 part of coupling agent; and 2 parts of chain extender.

[0048] The polyester polyol is poly(1,4-butylene adipate) diol; the bio-based polyether polyol is polytrimethylene ether glycol; the bio-based isocyanate is diphenylmethane diisocyanate; the filler is calcium carbonate; the catalyst is dibutyltin dilaurate; the coupling agent is aniline methyl triethoxysilane; and the chain extender is 1,4-butanediol.

[0049] The preparation method of functionalized polydopamine is as follows:

[0050] (1) Add dopamine hydrochloride to a reaction vessel containing Tris-HCl buffer, stir evenly, adjust the pH value to 8.6 with an alkaline solution, react for 22 hours at room temperature, centrifuge after the reaction is completed, wash the product with water, and dry to obtain polydopamine; the content of dopamine hydrochloride in each milliliter of Tris-HCl buffer is 4 mg; the alkaline solution is a 30wt% sodium hydroxide solution;

[0051] (2) Add polydopamine, a functional modifier and triethylamine to a reaction vessel containing a solvent, stir evenly, and react at a temperature of 55° C. for 5 hours. After the reaction is completed, centrifuge, wash the product with water, and dry to obtain functionalized polydopamine; the solvent is a 60% ethanol solution; the mass ratio of polydopamine, functional modifier, triethylamine, and solvent is 10:3:0.5:200.

[0052] A method for preparing a polyurethane hot melt adhesive composition comprises the following steps:

[0053] Step 1: Add polyester polyol, bio-based polyether polyol and functionalized polydopamine into a reaction container according to weight ratio, heat to 130° C., and dehydrate for 1.5 hours under vacuum to obtain a mixture;

[0054] Step 2: Cool the mixture to 70°C, add bio-based isocyanate and catalyst under nitrogen protection, heat to 85°C, stir for 2h, add filler, coupling agent and chain extender, continue stirring for 1h to obtain a hot melt adhesive composition.

[0055] Embodiment 3

[0056] A polyurethane hot melt adhesive composition comprises the following components in parts by weight: 50 parts of polyester polyol; 23 parts of bio-based polyether polyol; 28 parts of bio-based isocyanate; 18 parts of functionalized polydopamine; 7 parts of filler; 0.6 parts of catalyst; 0.5 parts of coupling agent; and 3 parts of chain extender.

[0057] The polyester polyol is polycaprolactone diol; the bio-based polyether polyol is polytrimethylene ether glycol; the bio-based isocyanate is dicyclohexylmethane diisocyanate; the filler is talc; the catalyst is dibutyltin dioctoate; the coupling agent is γ-aminopropyltriethoxysilane; and the chain extender is 1,2-propylene glycol.

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

[0059] (1) Add dopamine hydrochloride to a reaction vessel containing Tris-HCl buffer, stir evenly, adjust the pH value to 8.5 with an alkaline solution, react for 20 hours at room temperature, centrifuge after the reaction is completed, wash the product with water, and dry to obtain polydopamine; the content of dopamine hydrochloride in each milliliter of Tris-HCl buffer is 3 mg; the alkaline solution is a 20wt% potassium hydroxide solution;

[0060] (2) Add polydopamine, a functional modifier and triethylamine to a reaction vessel containing a solvent, stir evenly, and react at 60°C for 4 hours. After the reaction is completed, centrifuge, wash the product with water, and dry to obtain functionalized polydopamine; the solvent is a 50% ethanol solution; the mass ratio of polydopamine, functional modifier, triethylamine, and solvent is 10:2:0.3:150.

[0061] A method for preparing a polyurethane hot melt adhesive composition comprises the following steps:

[0062] Step 1: Add polyester polyol, bio-based polyether polyol and functionalized polydopamine into a reaction container according to weight ratio, heat to 120° C., and dehydrate for 2 hours under vacuum to obtain a mixture;

[0063] Step 2: Cool the mixture to 70°C, add bio-based isocyanate and catalyst under nitrogen protection, heat to 90°C, stir for 1.5 hours, add filler, coupling agent and chain extender, and continue stirring for 1.3 hours to obtain a hot melt adhesive composition.

[0064] Embodiment 4

[0065] A polyurethane hot melt adhesive composition comprises the following components in parts by weight: 40 parts of polyester polyol; 20 parts of bio-based polyether polyol; 25 parts of bio-based isocyanate; 15 parts of functionalized polydopamine; 5 parts of filler; 0.5 parts of catalyst; 0.7 parts of coupling agent; and 1 part of chain extender.

[0066] The polyester polyol is poly(hexanediol adipate) ester diol; the bio-based polyether polyol is polytrimethylene ether glycol; the bio-based isocyanate is 1,5-pentanediisocyanate; the filler is titanium dioxide; the catalyst is dibutyltin dioctoate; the coupling agent is vinyltriethoxysilane; and the chain extender is 1,6-hexanediol.

[0067] The preparation method of functionalized polydopamine is as follows:

[0068] (1) Add dopamine hydrochloride to a reaction vessel containing Tris-HCl buffer, stir evenly, adjust the pH value to 8.6 with an alkaline solution, react for 21 hours at room temperature, centrifuge after the reaction is completed, wash the product with water, and dry to obtain polydopamine; the content of dopamine hydrochloride in each milliliter of Tris-HCl buffer is 3.5 mg; the alkaline solution is a 20wt% sodium hydroxide solution;

[0069] (2) Add polydopamine, a functional modifier and triethylamine to a reaction vessel containing a solvent, stir evenly, and react at 50°C for 4.5 hours. After the reaction is completed, centrifuge, wash the product with water, and dry to obtain functionalized polydopamine; the solvent is 55% ethanol solution; the mass ratio of polydopamine, functional modifier, triethylamine, and solvent is 10:2.5:0.4:180.

[0070] A method for preparing a polyurethane hot melt adhesive composition comprises the following steps:

[0071] Step 1: Add polyester polyol, bio-based polyether polyol and functionalized polydopamine into a reaction container according to weight ratio, heat to 125° C., and dehydrate for 1.8 hours under vacuum to obtain a mixture;

[0072] Step 2: Cool the mixture to 70°C, add bio-based isocyanate and catalyst under nitrogen protection, heat to 80°C, stir for 1.8 hours, add filler, coupling agent and chain extender, and continue stirring for 1.5 hours to obtain a hot melt adhesive composition.

[0073] Embodiment 5

[0074] A polyurethane hot melt adhesive composition comprises the following components in parts by weight: 44 parts of polyester polyol; 24 parts of bio-based polyether polyol; 30 parts of bio-based isocyanate; 16 parts of functionalized polydopamine; 7 parts of filler; 0.6 parts of catalyst; 1 part of coupling agent; and 2 parts of chain extender.

[0075] The polyester polyol is poly(1,4-butylene adipate) diol; the bio-based polyether polyol is polytrimethylene ether glycol; the bio-based isocyanate is 1,5-pentanediisocyanate; the filler is talc; the catalyst is dibutyltin dilaurate; the coupling agent is γ-aminopropyltriethoxysilane; and the chain extender is 1,2-propylene glycol.

[0076] The preparation method of functionalized polydopamine is as follows:

[0077] (1) Add dopamine hydrochloride to a reaction vessel containing Tris-HCl buffer, stir evenly, adjust the pH value to 8.5 with an alkaline solution, react for 22 hours at room temperature, centrifuge after the reaction is completed, wash the product with water, and dry to obtain polydopamine; the content of dopamine hydrochloride in each milliliter of Tris-HCl buffer is 4 mg; the alkaline solution is a 30wt% potassium hydroxide solution;

[0078] (2) Add polydopamine, a functional modifier and triethylamine to a reaction vessel containing a solvent, stir evenly, and react at 60°C for 5 hours. After the reaction is completed, centrifuge, wash the product with water, and dry to obtain functionalized polydopamine; the solvent is 50% ethanol solution; the mass ratio of polydopamine, functional modifier, triethylamine, and solvent is 10:2.7:0.5:160.

[0079] A method for preparing a polyurethane hot melt adhesive composition comprises the following steps:

[0080] Step 1: Add polyester polyol, bio-based polyether polyol and functionalized polydopamine into a reaction container according to weight ratio, heat to 130° C., and dehydrate for 2 hours under vacuum to obtain a mixture;

[0081] Step 2: Cool the mixture to 70°C, add bio-based isocyanate and catalyst under nitrogen protection, heat to 85°C, stir for 1.5 hours, add filler, coupling agent and chain extender, continue stirring for 1 hour to obtain a hot melt adhesive composition.

[0082] Comparative Example 1

[0083] Compared with Example 2, in this comparative example, the functionalized polydopamine in the polyurethane hot melt adhesive composition is replaced with polydopamine.

[0084] A polyurethane hot melt adhesive composition comprises the following components in parts by weight: 45 parts of polyester polyol; 25 parts of bio-based polyether polyol; 30 parts of bio-based isocyanate; 20 parts of polydopamine; 10 parts of filler; 0.8 parts of catalyst; 1 part of coupling agent; and 2 parts of chain extender.

[0085] The polyester polyol is poly(1,4-butylene adipate) diol; the bio-based polyether polyol is polytrimethylene ether glycol; the bio-based isocyanate is diphenylmethane diisocyanate; the filler is calcium carbonate; the catalyst is dibutyltin dilaurate; the coupling agent is aniline methyl triethoxysilane; and the chain extender is 1,4-butanediol.

[0086] The preparation method of polydopamine is the same as step (1) of Example 2.

[0087] The preparation method of a polyurethane hot melt adhesive composition is the same as that of Example 2.

[0088] Comparative Example 2

[0089] Compared with Example 2, the polyurethane hot melt adhesive composition in this comparative example does not contain functionalized polydopamine.

[0090] A polyurethane hot melt adhesive composition comprises the following components in parts by weight: 45 parts of polyester polyol; 25 parts of bio-based polyether polyol; 30 parts of bio-based isocyanate; 10 parts of filler; 0.8 parts of catalyst; 1 part of coupling agent; and 2 parts of chain extender.

[0091] The polyester polyol is poly(1,4-butylene adipate) diol; the bio-based polyether polyol is polytrimethylene ether glycol; the bio-based isocyanate is diphenylmethane diisocyanate; the filler is calcium carbonate; the catalyst is dibutyltin dilaurate; the coupling agent is aniline methyl triethoxysilane; and the chain extender is 1,4-butanediol.

[0092] The preparation method of a polyurethane hot melt adhesive composition is the same as that of Example 2.

[0093] Performance Testing

[0094] The performance tests were performed on the polyurethane hot melt adhesive compositions prepared in Examples 2 to 5 and Comparative Examples 1 to 2, wherein the adhesion was tested according to GB / T 2791-1995 standard, and the initial and final adhesion were tested; the tensile strength and elongation at break were tested according to GB / T 528-2009 standard, and the test conditions were 25°C and 50% RH; the hydrophobicity was tested according to GB / T 30693-2014 standard; the limiting oxygen index was tested according to GB / T 2406-2009 standard; the antibacterial property was tested by the inhibition zone method, and the cured adhesive layer was cut into small pieces of 0.5×0.5 cm, and 200 μL of Escherichia coli suspension (10 6cfu / mL) were applied to the PDA plate culture medium, and the small piece of the gelatin layer was placed in the center of the culture dish. The culture was cultured at 37°C for 24 hours, and the diameter of the inhibition zone was measured. The test results are shown in Table 1 below.

[0095] Table 1 Performance test results

[0096]

[0097] As shown in Table 1, the adhesion, tensile strength, elongation at break, water contact angle, limiting oxygen index and antibacterial zone diameter of the polyurethane hot melt adhesive compositions prepared in Examples 2 to 5 are all higher than those in Comparative Examples 1 to 2, indicating that the polyurethane hot melt adhesive composition provided by the present invention has good adhesion, mechanical properties, waterproofness, flame retardancy and antibacterial properties; compared with Comparative Examples 1 to 2, functionalized polydopamine is added to the components of the polyurethane hot melt adhesive composition in Example 2 of the present invention, and the polydopamine structure containing catechol groups itself has good adhesion and antibacterial effects, can participate in the synthesis of polyurethane, and is helpful to improve the adhesion of the polyurethane hot melt adhesive; the functional modifier containing antibacterial long-chain quaternary ammonium salt groups, hydrophobic difluorophenyl groups, and flame retardant phosphite groups grafted into the functionalized polydopamine can also further enhance the antibacterial, flame retardant and waterproof properties of the polyurethane hot melt adhesive; the rigid benzene ring structure contained in the functionalized polydopamine can ensure the strength of the polyurethane hot melt adhesive, while the flexible long-chain (dodecyl) quaternary ammonium salt group can also give the polyurethane hot melt adhesive good flexibility.

[0098] 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.

[0099] Although the embodiments of the present application 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 application, and that the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A polyurethane hot melt adhesive composition, characterized in that: The polyurethane hot melt adhesive composition comprises the following components by weight: 40-50 parts of polyester polyol; 20-25 parts of bio-based polyether polyol; 25-30 parts of bio-based isocyanate; 15-20 parts of functionalized polydopamine; 5-10 parts of filler; 0.5-0.8 parts of catalyst; 0.5-1 parts of coupling agent; 1-3 parts of chain extender; the preparation method of the functionalized polydopamine is: (1) Add dopamine hydrochloride to a reaction vessel containing Tris-HCl buffer, stir evenly, adjust the pH value to 8.5-8.6 with an alkaline solution, react for 20-22 hours at room temperature, and after the reaction is completed, centrifuge, wash the product with water, and dry it to obtain polydopamine; (2) Add polydopamine, a functional modifier and triethylamine to a reaction vessel containing a solvent, stir evenly, and react at a temperature of 50-60° C. for 4-5 hours. After the reaction is completed, centrifuge, wash the product with water, and dry it to obtain functionalized polydopamine; the functional modifier is prepared by reacting 4-chlorophenylethylamine with dodecyldimethyl tertiary amine, epichlorohydrin, diethylphosphite chloride, and 2,6-difluorobenzyl chloride in sequence; the chemical structure of the functional modifier is: 。 2. A polyurethane hot melt adhesive composition according to claim 1, characterized in that: In step (1), the content of dopamine hydrochloride in each milliliter of Tris-HCl buffer is 3-4 mg; and the alkaline solution is a 20-30 wt % sodium hydroxide or potassium hydroxide solution.

3. A polyurethane hot melt adhesive composition according to claim 1, characterized in that: The solvent in step (2) is a 50-60% ethanol solution; the mass ratio of the polydopamine, the functional modifier, the triethylamine, and the solvent is 10:2-3:0.3-0.5:150-200.

4. The polyurethane hot melt adhesive composition according to claim 1, characterized in that: The preparation method of the functional modifier in step (2) is: S1. Add 4-chlorophenylethylamine and dodecyldimethyl tertiary amine to a reaction vessel containing ethanol, stir evenly, and reflux at 80° C. for 10-11 hours to obtain intermediate 1; S2, add intermediate 1 to a reaction vessel containing anhydrous chloroform, stir evenly, slowly drop epichlorohydrin, after the dropwise addition is complete, stir and react for 4-5 hours at a temperature of 35-40°C, then place the reaction vessel in an ice bath, add triethylamine, stir evenly, drop diethylphosphite chloride, after the dropwise addition is complete, continue to react for 3-4 hours under ice bath conditions to obtain intermediate 2; S3. Add intermediate 2, 2,6-difluorobenzyl chloride, potassium iodide and potassium carbonate to a reaction vessel containing N,N-dimethylformamide, stir evenly, and react for 5-6 hours at room temperature to obtain a functional modifier.

5. A polyurethane hot melt adhesive composition according to claim 4, characterized in that: The molar ratio of 4-chlorophenylethylamine and dodecyldimethyl tertiary amine in step S1 is 1:1.1-1.2; the molar ratio of intermediate 1, epichlorohydrin, diethylphosphite chloride and triethylamine in step S2 is 1:1-1.1:1.1-1.2:1.3-1.5; the molar ratio of intermediate 2, 2,6-difluorobenzyl chloride, potassium iodide and potassium carbonate in step S3 is 1:1.1-1.2:1.1-1.2:1.3-1.

4.

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

7. The polyurethane hot melt adhesive composition according to claim 1, characterized in that: The bio-based polyether polyol is polytrimethylene ether glycol; the bio-based isocyanate is any one of diphenylmethane diisocyanate, 1,5-pentane diisocyanate, and dicyclohexylmethane diisocyanate, or a mixture of several of them.

8. The polyurethane hot melt adhesive composition according to claim 1, characterized in that: The filler is any one of talcum powder, calcium carbonate and titanium dioxide or a mixture of the two or more thereof; the catalyst is dibutyltin dilaurate or dibutyltin dioctoate.

9. The polyurethane hot melt adhesive composition according to claim 1, characterized in that: The coupling agent is any one of aniline methyl triethoxysilane, vinyl triethoxysilane, and γ-aminopropyl triethoxysilane, or a mixture of several of them; the chain extender is any one of 1,4-butanediol, 1,2-propylene glycol, and 1,6-hexanediol, or a mixture of several of them.

10. Use of the polyurethane hot melt adhesive composition according to any one of claims 1 to 9 in the fields of packaging, automobile industry and construction.

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