A sweat-resistant PUR hot melt adhesive and its preparation method

Abstract

The present invention relates to a sweat-resistant PUR hot melt adhesive and a preparation method thereof, and relates to the field of hot melt adhesives. The sweat-resistant PUR hot melt adhesive comprises the following raw materials in parts by weight: 35-42 parts of a fluorinated polyether polyol; 20-30 parts of a polyester polyol; 12-17 parts of hydroxyl-terminated polybutadiene; 16-20 parts of a diisocyanate; 0.05-0.2 parts of a catalyst; 10-18 parts of an acrylic resin; and 0.1-0.5 parts of an antioxidant. The present invention improves the PUR hot melt adhesive's resistance to sweat and sebum corrosion, thereby extending the service life of electronic wearable devices.

Description

Technical Field

[0001] The present invention relates to the field of hot melt adhesives, in particular to a sweat-resistant PUR hot melt adhesive and a preparation method thereof. Background Art

[0002] PUR hot melt adhesive, also known as moisture-curing reactive polyurethane hot melt adhesive, is primarily composed of isocyanate-terminated polyurethane prepolymers. PUR hot melt adhesives contain polar and chemically active urethane (-NHCOO-) or isocyanate (-NCO) groups in their molecular structure. These compounds, combined with active hydrogen-containing materials, offer excellent heat resistance, bond strength, chemical resistance, and aging resistance. They are widely used in packaging, wood processing, textiles, bookbinding, electrical and electronics, and other fields.

[0003] As wearable products become more and more intelligent, electronic wearable devices are growing rapidly. The internal parts of electronic wearable devices are connected with glue to form protection. PUR hot melt adhesive has the advantages of environmental protection, energy saving, fast positioning, and provides high initial adhesion strength. It is used in the bonding of electronic wearable devices.

[0004] However, when existing PUR hot melt adhesive is used in electronic wearable devices, due to long-term contact with the human body, the sweat and oil secreted by the body slowly penetrate into the interior of the electronic wearable devices. The existing PUR hot melt adhesive has poor resistance to sweat and sebum corrosion. Once sweat penetrates, it will destroy the bonding strength, causing debonding or even damage, which will shorten the life of the electronic wearable devices. Summary of the Invention

[0005] In order to improve the performance of PUR hot melt adhesive in resisting sweat and sebum corrosion and prolong the service life of electronic wearable devices, the present application provides a sweat-resistant PUR hot melt adhesive and a preparation method thereof.

[0006] The present application provides a sweat-resistant PUR hot melt adhesive and a preparation method thereof, which adopts the following technical solutions: In a first aspect, a sweat-resistant PUR hot melt adhesive comprises the following raw materials in parts by weight:

[0007] 35-42 parts of fluorinated polyether polyol;

[0008] 20-30 parts of polyester polyol;

[0009] 12-17 parts of hydroxy-terminated polybutadiene;

[0010] 16-20 parts of diisocyanate;

[0011] Catalyst 0.05-0.2 parts;

[0012] 10-18 parts of acrylic resin;

[0013] 0.1-0.5 parts of antioxidant.

[0014] The above technical solution is adopted, and end-hydroxyl polybutadiene is selected to modify the polyurethane hot melt adhesive. End-hydroxyl polybutadiene has the advantages of good oil resistance, excellent water resistance and aging resistance. The hydroxyl group at the end of the molecular chain is cross-linked and cured with diisocyanate, and the obtained polyurethane hot melt adhesive has excellent acid and alkali resistance, sweat corrosion resistance and good bonding strength. Fluorine-containing polyether polyol is adopted, and organic fluorine is introduced into the soft segment to make the polyurethane hot melt adhesive contain organic fluorine. The introduction of fluorine element is conducive to improving the oil and water repellency and chemical corrosion resistance of the polyurethane hot melt adhesive. The polyurethane hot melt adhesive is formed by cross-linking fluorine-containing polyether polyol, polyester polyol, end-hydroxyl polybutadiene and diisocyanate. It has good sweat and sebum corrosion resistance, is suitable for bonding electronic wearable devices, and extends the service life of electronic wearable devices.

[0015] Optionally, the number average molecular weight of the fluorine-containing polyether polyol is 1500-3000, and the fluorine content is 10-30%.

[0016] By adopting the above technical solution, too high fluorine content will affect the toughness and elongation at break of the polyurethane hot melt adhesive. Controlling the number average molecular weight and fluorine content of the fluorinated polyether polyol makes the polyurethane hot melt adhesive have good fluidity and toughness and can withstand certain deformation.

[0017] Optionally, the fluorinated polyether polyol is prepared from the following raw materials in parts by weight:

[0018] 20-30 parts of isophorone diisocyanate;

[0019] 25-40 parts of octafluoropentanol;

[0020] 85-98 parts of glycidol;

[0021] 42-47 parts of tetrahydrofuran;

[0022] 0.3-0.8 parts of boron trifluoride etherate;

[0023] 1-3 parts of ethylene glycol;

[0024] 65-72 parts of solvent.

[0025] Using the above technical solution, isophorone diisocyanate, octafluoropentanol, and glycidol are selected to react to form a fluorinated epoxy compound, which is then reacted with tetrahydrofuran to form a fluorinated polyether polyol. The fluorinated polyether polyol contains isocyanate groups, which can react with polyester polyols and terminal hydroxyl polybutadiene during cross-linking, thereby increasing the cross-linking density of the polyurethane system, which is beneficial to improving the bonding strength and sweat and sebum corrosion resistance of the polyurethane hot melt adhesive.

[0026] Optionally, the hydroxyl-terminated polybutadiene is modified hydroxyl-terminated polybutadiene, and the modified hydroxyl-terminated polybutadiene is prepared from the following raw materials in parts by weight:

[0027] 10-14 parts of hydroxy-terminated polybutadiene;

[0028] 1.5-2.2 parts of 1-chloro-2,4-dinitrobenzene;

[0029] 20-25 parts of dichloromethane;

[0030] 1.7-2 parts of sodium hydroxide.

[0031] Using the above technical solution, 1-chloro-2,4-dinitrobenzene is selected to functionally modify the terminal carbon atoms of terminal hydroxyl polybutadiene, introducing phenyl and nitro groups. The benzene ring has a rigid structure, and the isocyanate group and the nitro group produce hydrogen bonds, which is beneficial to increase the cross-linking density of the polyurethane system and improve the mechanical properties and bonding strength of the polyurethane hot melt adhesive.

[0032] Optionally, the polyester polyol is polymerized from adipic acid and at least one diol selected from the group consisting of 1,4-butanediol, neopentyl glycol, ethylene glycol, diethylene glycol and 1,6-hexanediol.

[0033] Optionally, the diisocyanate is selected from one or more of diphenylmethane diisocyanate, toluene diisocyanate, xylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and carbodiimide-modified diisocyanate.

[0034] Optionally, the catalyst is one or more of dibutyltin dilaurate, stannous octoate, dibutylene acetate, triethylenediamine, and bismorpholinyl diethyl ether.

[0035] In a second aspect, the present application discloses a method for preparing a sweat-resistant PUR hot melt adhesive, comprising the following steps: adding polyester polyol, fluorinated polyether polyol, hydroxyl-terminated polybutadiene, and acrylic resin into a reactor, stirring and mixing them uniformly, heating to 120-130° C., vacuuming to -0.095-0.05 MPa, and dehydrating for 2-2.5 hours;

[0036] Cool down to 75-80℃, add diisocyanate and catalyst, and react at 85-90℃ for 2-3h; add antioxidant, and stir rapidly at 110-120℃ for 20-30min;

[0037] The material is quickly discharged and packaged under nitrogen protection to obtain PUR hot melt adhesive that is resistant to sweat corrosion.

[0038] By adopting the above technical solution, the preparation process is relatively simple. Under the synergistic effect of multiple raw materials, the prepared PUR hot melt adhesive improves the acid, alkali, sweat and sebum resistance while ensuring the bonding strength and mechanical properties.

[0039] Optionally, the fluorinated polyether polyol is prepared by the following steps:

[0040] Isophorone diisocyanate and octafluoropentanol are placed in a reactor, reacted at 40-45°C for 2-2.5 hours, then heated to 65-68°C, glycidol is added, and the reaction is continued for 2-2.5 hours to obtain a fluorinated epoxy compound;

[0041] Add solvent, ethylene glycol and boron trifluoride etherate to the reaction kettle, stir at 0-2°C for 15-20 minutes, add fluorinated epoxy compound and tetrahydrofuran dropwise, the temperature should not exceed 5°C during the addition process, and react for 5-6 hours;

[0042] Add a small amount of deionized water and stir for 20-30 minutes to stop the reaction. Wash with deionized water until the organic phase is neutral. Use a separatory funnel to separate the layers. Take the lower organic phase and distill under reduced pressure to obtain fluorinated polyether polyol.

[0043] Using the above technical solution, isophorone diisocyanate, octafluoropentanol, and glycidol are selected to react to form a fluorinated epoxy compound, which is then reacted with tetrahydrofuran to form a fluorinated polyether polyol. Ethylene glycol and boron trifluoride etherate are used as co-initiators and cationic initiators, respectively, making the polymerization process controllable and convenient for regulating the molecular weight of the fluorinated polyether polyol.

[0044] Optionally, when the hydroxy-terminated polybutadiene is modified hydroxy-terminated polybutadiene, the preparation steps are as follows:

[0045] Weigh terminal hydroxyl polybutadiene and dichloromethane into a stirring kettle, stir to dissolve, add sodium hydroxide under nitrogen protection and stir for 20-30 minutes, add 1-chloro-2,4-dinitrobenzene into the stirring kettle, stir for 2-3 hours, and then react at room temperature for 10-12 hours, wash with anhydrous methanol and n-hexane, stand for separation, and obtain modified terminal hydroxyl polybutadiene after distillation.

[0046] By adopting the technical solution, the preparation process is simple and the yield of the modified hydroxy-terminated polybutadiene is high.

[0047] In summary, this application has the following beneficial effects:

[0048] 1. Hydroxyl-terminated polybutadiene is used to modify the polyurethane hot melt adhesive. Hydroxyl-terminated polybutadiene has the advantages of good oil resistance, excellent water resistance, and aging resistance. The hydroxyl group at the end of the molecular chain is cross-linked and cured with diisocyanate. The resulting polyurethane hot melt adhesive has excellent acid and alkali resistance, sweat corrosion resistance, and good bonding strength. Fluorine-containing polyether polyol is used. By introducing organic fluorine into the soft segment, the polyurethane hot melt adhesive contains organic fluorine. The introduction of fluorine element is conducive to improving the oil and water repellency and chemical corrosion resistance of the polyurethane hot melt adhesive. The polyurethane hot melt adhesive is formed by cross-linking fluorine-containing polyether polyol, polyester polyol, hydroxyl-terminated polybutadiene, and diisocyanate. It has good sweat and sebum corrosion resistance and is suitable for bonding electronic wearable devices, extending the service life of electronic wearable devices.

[0049] 2. Isophorone diisocyanate, octafluoropentanol, and glycidol are reacted to form a fluorinated epoxy compound, which is then reacted with tetrahydrofuran to form a fluorinated polyether polyol. The fluorinated polyether polyol contains isocyanate groups, which can react with polyester polyols and terminal hydroxyl polybutadiene during cross-linking, thereby increasing the cross-linking density of the polyurethane system, which is beneficial to improving the bonding strength and sweat and sebum corrosion resistance of the polyurethane hot melt adhesive.

[0050] 3. 1-Chloro-2,4-dinitrobenzene is used to functionally modify the terminal carbon atoms of the hydroxy-terminated polybutadiene, introducing phenyl and nitro groups. The benzene ring has a rigid structure, and the isocyanate group and the nitro group produce hydrogen bonds, which is beneficial to increase the cross-linking density of the polyurethane system and improve the mechanical properties and bonding strength of the polyurethane hot melt adhesive. DETAILED DESCRIPTION

[0051] The present application is further described in detail below in conjunction with Examples 1-8 and Comparative Examples 1-2.

[0052] Preparation Example

[0053] Preparation Example 1

[0054] The preparation of fluorinated polyether polyol includes the following raw materials in parts by weight:

[0055] 20 parts of isophorone diisocyanate;

[0056] 25 parts of octafluoropentanol;

[0057] 85 parts of glycidol;

[0058] 42 parts of tetrahydrofuran;

[0059] 0.3 parts of boron trifluoride etherate;

[0060] 1 part of ethylene glycol;

[0061] 65 parts of solvent, dichloromethane is selected as the solvent.

[0062] Fluorinated polyether polyols are prepared by the following steps:

[0063] Isophorone diisocyanate and octafluoropentanol were placed in a reactor, reacted at 40°C for 2 hours, then heated to 65°C, glycidol was added and the reaction was continued for 2 hours to obtain a fluorinated epoxy compound;

[0064] Add solvent, ethylene glycol and boron trifluoride etherate to the reaction kettle, stir at 0°C for 15 minutes, add fluorinated epoxy compound and tetrahydrofuran dropwise at a temperature not exceeding 5°C, and react at 0°C for 5 hours;

[0065] Add a small amount of deionized water and stir for 20 minutes to stop the reaction. Wash with deionized water twice the volume of the reaction solution and stir for 5 minutes until the organic phase is neutral. Use a separatory funnel to separate the reaction solution into layers, take the lower organic phase and distill it under reduced pressure to obtain fluorinated polyether polyol.

[0066] The molecular weight of the prepared fluorinated polyether polyol is 1600 and the fluorine content is 12%.

[0067] Preparation Example 2

[0068] The preparation of fluorinated polyether polyol includes the following raw materials in parts by weight:

[0069] 30 parts of isophorone diisocyanate;

[0070] 40 parts of octafluoropentanol;

[0071] 98 parts of glycidol;

[0072] 47 parts of tetrahydrofuran;

[0073] 0.8 parts of boron trifluoride etherate;

[0074] 3 parts of ethylene glycol;

[0075] 72 parts of solvent, 52 parts of dichloromethane and 20 parts of chloroform are selected as the solvent.

[0076] Fluorinated polyether polyols are prepared by the following steps:

[0077] Isophorone diisocyanate and octafluoropentanol were placed in a reactor, reacted at 45°C for 2.5 hours, then heated to 68°C, glycidol was added, and the reaction was continued for 2.5 hours to obtain a fluorinated epoxy compound;

[0078] Add the solvent, ethylene glycol and boron trifluoride etherate to the reaction kettle, stir at 2°C for 20 minutes, add the fluorinated epoxy compound and tetrahydrofuran dropwise at a temperature not exceeding 5°C, and react at 2°C for 6 hours;

[0079] Add a small amount of deionized water and stir for 30 minutes to stop the reaction. Wash with deionized water twice the volume of the reaction solution and stir for 5 minutes until the organic phase is neutral. Use a separatory funnel to separate the reaction solution into layers, remove the lower organic phase and perform vacuum distillation to obtain fluorinated polyether polyol.

[0080] The molecular weight of the prepared fluorinated polyether polyol is 2200 and the fluorine content is 23%.

[0081] Preparation Example 3

[0082] The modified hydroxy-terminated polybutadiene is prepared from the following raw materials in parts by weight:

[0083] 10 parts of hydroxy-terminated polybutadiene;

[0084] 1.5 parts of 1-chloro-2,4-dinitrobenzene;

[0085] 20 parts of dichloromethane;

[0086] 1.7 parts of sodium hydroxide.

[0087] The preparation method of modified hydroxy-terminated polybutadiene comprises the following steps:

[0088] Weigh terminal hydroxyl polybutadiene and dichloromethane into a stirring kettle, stir to dissolve, add sodium hydroxide under nitrogen protection and stir for 20 minutes, add 1-chloro-2,4-dinitrobenzene to the stirring kettle, stir for 2 hours, and then react at room temperature for 10 hours, wash with anhydrous methanol and n-hexane several times, pour into a separating funnel, stand still for separation, and obtain modified terminal hydroxyl polybutadiene after distillation.

[0089] Preparation Example 4

[0090] The modified hydroxy-terminated polybutadiene is prepared from the following raw materials in parts by weight:

[0091] 14 parts of hydroxy-terminated polybutadiene;

[0092] 2.2 parts of 1-chloro-2,4-dinitrobenzene;

[0093] 25 parts of dichloromethane;

[0094] 2 parts of sodium hydroxide.

[0095] The preparation method of modified hydroxy-terminated polybutadiene comprises the following steps:

[0096] Weigh terminal hydroxyl polybutadiene and dichloromethane into a stirring kettle, stir to dissolve, add sodium hydroxide under nitrogen protection and stir for 30 minutes, add 1-chloro-2,4-dinitrobenzene to the stirring kettle, stir for 3 hours, and then react at room temperature for 12 hours, wash with anhydrous methanol and n-hexane several times, pour into a separating funnel, stand still for separation, and obtain modified terminal hydroxyl polybutadiene after distillation.

[0097] Example

[0098] Example 1

[0099] The sweat-resistant PUR hot melt adhesive comprises the following raw materials in parts by weight:

[0100] 35 parts of fluorinated polyether polyol, specifically BHD-1801F, with a number average molecular weight of 3000 and a fluorine content of 25%, purchased from Beijing Beihua Engineering Technology Co., Ltd.;

[0101] 20 parts of polyester polyol, specifically a polyester polyol with an average molecular weight of 2000 prepared by polymerization of adipic acid and 1,6-hexanediol;

[0102] 12 parts of hydroxy-terminated polybutadiene;

[0103] 16 parts of diisocyanate, specifically hexamethylene diisocyanate;

[0104] 0.05 parts of catalyst, specifically dibutyltin dilaurate;

[0105] 10 parts of acrylic resin, specifically BASF 682 acrylic resin;

[0106] 0.1 part of antioxidant, specifically antioxidant 1010.

[0107] A method for preparing a sweat-resistant PUR hot melt adhesive comprises the following steps:

[0108] Add polyester polyol, fluorinated polyether polyol, hydroxyl-terminated polybutadiene and acrylic resin into a reactor, stir and mix evenly, heat to 120°C, vacuum to -0.095MPa, and dehydrate for 2h;

[0109] Cool down to 75°C, add diisocyanate and catalyst, and react at 85°C for 2h; add antioxidant, and stir rapidly at 110°C for 20min;

[0110] The material is quickly discharged and packaged under nitrogen protection to obtain PUR hot melt adhesive that is resistant to sweat corrosion.

[0111] Example 2

[0112] The sweat-resistant PUR hot melt adhesive comprises the following raw materials in parts by weight:

[0113] 42 parts of fluorinated polyether polyol, specifically FX1402, with a number average molecular weight of 2400 and a fluorine content of 15%, purchased from Tianjin Feixin Trading Co., Ltd.;

[0114] 30 parts of polyester polyol, specifically a polyester polyol with an average molecular weight of 2400 prepared by polymerization of adipic acid and neopentyl glycol;

[0115] 17 parts of hydroxy-terminated polybutadiene;

[0116] 20 parts of diisocyanate, specifically diphenylmethane diisocyanate;

[0117] 0.2 parts of catalyst, specifically bismorpholinyl diethyl ether;

[0118] 18 parts of acrylic resin, specifically Xinlian 902 acrylic resin;

[0119] 0.5 parts of antioxidant, specifically antioxidant 168.

[0120] A method for preparing a sweat-resistant PUR hot melt adhesive comprises the following steps:

[0121] Add polyester polyol, fluorinated polyether polyol, hydroxyl-terminated polybutadiene and acrylic resin into a reactor, stir and mix evenly, heat to 130°C, vacuum to 0.05 MPa, and dehydrate for 2.5 hours;

[0122] Cool down to 80℃, add diisocyanate and catalyst, and react at 90℃ for 3h; add antioxidant, and stir rapidly at 120℃ for 30min;

[0123] The material is quickly discharged and packaged under nitrogen protection to obtain PUR hot melt adhesive that is resistant to sweat corrosion.

[0124] Example 3

[0125] The sweat-resistant PUR hot melt adhesive comprises the following raw materials in parts by weight:

[0126] 38 parts of fluorinated polyether polyol, specifically FX3302, with a number average molecular weight of 2000 and a fluorine content of 20%, purchased from Tianjin Feixin Trading Co., Ltd.;

[0127] 25 parts of polyester polyol, specifically a polyester polyol with an average molecular weight of 2800 prepared by polymerization of adipic acid, 1,4-butanediol and diethylene glycol;

[0128] 14 parts of hydroxy-terminated polybutadiene;

[0129] 18 parts of diisocyanate, specifically toluene diisocyanate;

[0130] 0.13 parts of catalyst, specifically stannous octoate;

[0131] 15 parts of acrylic resin, specifically Hanhua Soluryl-70 acrylic resin;

[0132] 0.3 parts of antioxidant, specifically antioxidant 1010.

[0133] A method for preparing a sweat-resistant PUR hot melt adhesive comprises the following steps:

[0134] Add polyester polyol, fluorinated polyether polyol, hydroxyl-terminated polybutadiene and acrylic resin into a reactor, stir and mix evenly, heat to 125°C, vacuum to 0.03 MPa, and dehydrate for 2 hours;

[0135] Cool down to 78°C, add diisocyanate and catalyst, and react at 87°C for 3 hours; add antioxidant and stir rapidly at 115°C for 25 minutes;

[0136] The material is quickly discharged and packaged under nitrogen protection to obtain PUR hot melt adhesive that is resistant to sweat corrosion.

[0137] Example 4

[0138] The difference between this embodiment and embodiment 1 is that the fluorine-containing polyether polyol in the raw material is different.

[0139] The fluorinated polyether polyol of this embodiment is the fluorinated polyether polyol prepared in Preparation Example 1.

[0140] Example 5

[0141] The difference between this embodiment and embodiment 1 is that the fluorine-containing polyether polyol in the raw material is different.

[0142] The fluorinated polyether polyol of this embodiment is the fluorinated polyether polyol prepared in Preparation Example 2.

[0143] Example 6

[0144] The difference between this embodiment and embodiment 1 is that the hydroxy-terminated polybutadiene in the raw material is different.

[0145] The hydroxy-terminated polybutadiene of this embodiment is the modified hydroxy-terminated polybutadiene prepared in Preparation Example 3.

[0146] Example 7

[0147] The difference between this embodiment and embodiment 1 is that the hydroxy-terminated polybutadiene in the raw material is different.

[0148] The hydroxy-terminated polybutadiene of this embodiment is the modified hydroxy-terminated polybutadiene prepared in Preparation Example 4.

[0149] Example 8

[0150] The difference between this embodiment and embodiment 1 is that the fluorine-containing polyether polyol and the hydroxyl-terminated polybutadiene in the raw materials are different.

[0151] The fluorinated polyether polyol of this embodiment is the fluorinated polyether polyol prepared in Preparation Example 2, and the hydroxy-terminated polybutadiene is the modified hydroxy-terminated polybutadiene prepared in Preparation Example 3.

[0152] Comparative Example

[0153] Comparative Example 1

[0154] The difference between this comparative example and Example 1 is that no hydroxyl-terminated polybutadiene is added to the hot melt adhesive raw material.

[0155] Comparative Example 2

[0156] The difference between this comparative example and Example 1 is that in this comparative example, polytetramethylene ether glycol with a molecular weight of 2000 is selected instead of fluorine-containing polyether polyol.

[0157] Performance testing

[0158] The PUR hot melt adhesives prepared in Examples 1-8 and Comparative Examples 1-2 were tested. When using PUR hot melt adhesive, the heating system was first turned on, the temperature was set to 100-130°C, and the adhesive was applied with a glue gun. The application process was ensured to be completed within the open time, and then the test was performed according to the regulations.

[0159] The bonding strength, sweat corrosion resistance, and sebum corrosion resistance of the PUR hot melt adhesive were tested, and the test results are recorded in Table 1.

[0160] Adhesion strength: Refer to GB / T 7124-2008 to prepare samples and test the tensile shear strength of PUR hot melt adhesive bonded to PC materials. The samples were cured for 7 days at 25°C and 50% RH.

[0161] Sweat corrosion resistance: PUR hot melt adhesive was used to stick PC material to prepare samples. The samples were immersed in artificial simulated sweat, packaged (sealed) with PE bags, and immersed in a constant temperature and humidity chamber at 25°C and 50% RH for 7 days. The samples were taken out and dried, and the corresponding shear strength was tested, and the attenuation rate 1 was calculated.

[0162] Sebum corrosion resistance: PUR hot melt adhesive was pasted to PC material to prepare samples. The samples were immersed in artificial sebum that complies with ASTM D4265-14. The samples were packaged (sealed) with PE bags and placed in a constant temperature and humidity chamber at 25°C and 50% RH for 7 days. The samples were taken out and dried, and the corresponding shear strength was tested. The attenuation rate 2 was calculated.

[0163] Table 1

[0164]

[0165] As can be seen from Table 1, the PUR hot melt adhesive prepared in this application is a combination of fluorinated polyether polyol and polyester polyol, and the polyurethane hot melt adhesive is modified by end-hydroxy polybutadiene. The cross-linked polyurethane hot melt adhesive has good bonding strength and excellent resistance to sweat and sebum corrosion, and is suitable for the bonding of electronic wearable devices.

[0166] Compared with Example 1, Example 4-5 uses homemade fluorinated polyether polyol. The fluorinated polyether polyol contains isocyanate groups, which can participate in the reaction with hydroxyl groups, increase the cross-linking density of the polyurethane system, and help improve the bonding strength and sweat and sebum corrosion resistance of the polyurethane hot melt adhesive.

[0167] Compared with Example 1, Example 6-7 uses 1-chloro-2,4-dinitrobenzene to functionally modify the terminal carbon atom of the terminal hydroxyl polybutadiene, introducing a rigid benzene ring structure. At the same time, the introduced nitro group can produce hydrogen bonds with the isocyanate group, thereby enhancing the intermolecular force and the cross-linking density of the system, which is beneficial to improving the bonding strength. At the same time, the polyurethane system with strong cross-linking properties can better withstand corrosion from sweat and skin, and is less prone to degumming and damage.

[0168] Compared with Example 1, Comparative Examples 1-2 lack the introduction of organic fluorine and the modification of terminal hydroxyl polybutadiene in the raw materials of the hot melt adhesive, respectively, which reduces the oil resistance and water resistance of the PUR hot melt adhesive and reduces the resistance to sweat and sebum corrosion.

[0169] This specific implementation manner is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the specific implementation manner as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A sweat-resistant PUR hot melt adhesive, characterized in that: The invention comprises the following raw materials in parts by weight: 35-42 parts of fluorinated polyether polyol; 20-30 parts of polyester polyol; 12-17 parts of hydroxy-terminated polybutadiene; 16-20 parts of diisocyanate; Catalyst 0.05-0.2 parts; 10-18 parts of acrylic resin; 0.1-0.5 parts of antioxidant; The fluorinated polyether polyol is prepared from the following raw materials in parts by weight: 20-30 parts of isophorone diisocyanate; 25-40 parts of octafluoropentanol; 85-98 parts of glycidol; 42-47 parts of tetrahydrofuran; 0.3-0.8 parts of boron trifluoride etherate; 1-3 parts of ethylene glycol; 65-72 parts of solvent; The hydroxyl-terminated polybutadiene is 1-chloro-2,4-dinitrobenzene modified hydroxyl-terminated polybutadiene.

2. The sweat-resistant PUR hot melt adhesive according to claim 1, characterized in that: The number average molecular weight of the fluorine-containing polyether polyol is 1500-3000, and the fluorine content is 10-30%.

3. The sweat-resistant PUR hot melt adhesive according to claim 1, characterized in that: The hydroxyl-terminated polybutadiene is modified hydroxyl-terminated polybutadiene, and the modified hydroxyl-terminated polybutadiene is prepared by the following raw materials in parts by weight: 10-14 parts of hydroxy-terminated polybutadiene; 1.5-2.2 parts of 1-chloro-2,4-dinitrobenzene; 20-25 parts of dichloromethane; 1.7-2 parts of sodium hydroxide.

4. The sweat-resistant PUR hot melt adhesive according to claim 1, characterized in that: The polyester polyol is prepared by polymerizing adipic acid with at least one diol selected from 1,4-butanediol, neopentyl glycol, ethylene glycol, diethylene glycol and 1,6-hexanediol.

5. The sweat-resistant PUR hot melt adhesive according to claim 1, characterized in that: The diisocyanate is selected from one or more of diphenylmethane diisocyanate, toluene diisocyanate, xylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and carbodiimide-modified diisocyanate.

6. The sweat-resistant PUR hot melt adhesive according to claim 1, characterized in that: The catalyst is one or more of dibutyltin dilaurate, stannous octoate, dibutylene acetate, triethylenediamine, and bismorpholinyl diethyl ether.

7. The method for preparing a sweat-resistant PUR hot melt adhesive according to any one of claims 1 to 6, characterized in that: The following steps are involved: Add polyester polyol, fluorinated polyether polyol, hydroxyl-terminated polybutadiene and acrylic resin into a reaction kettle, stir and mix evenly, heat to 120-130°C, vacuum degree to -0.095-0.05MPa, and dehydrate for 2-2.5h; Cool down to 75-80℃, add diisocyanate and catalyst, and react at 85-90℃ for 2-3h; add antioxidant, and stir rapidly at 110-120℃ for 20-30min; The material is quickly discharged and packaged under nitrogen protection to obtain PUR hot melt adhesive that is resistant to sweat corrosion.

8. The method for preparing a sweat-resistant PUR hot melt adhesive according to claim 7, characterized in that: The fluorinated polyether polyol is prepared by the following steps: Isophorone diisocyanate and octafluoropentanol are placed in a reactor, reacted at 40-45°C for 2-2.5 hours, then heated to 65-68°C, glycidol is added, and the reaction is continued for 2-2.5 hours to obtain a fluorinated epoxy compound; Add solvent, ethylene glycol and boron trifluoride etherate to the reaction kettle, stir at 0-2°C for 15-20 minutes, add fluorinated epoxy compound and tetrahydrofuran dropwise, the temperature should not exceed 5°C during the addition process, and react for 5-6 hours; Add a small amount of deionized water and stir for 20-30 minutes to stop the reaction. Wash with deionized water until the organic phase is neutral. Use a separatory funnel to separate the layers. Take the lower organic phase and distill under reduced pressure to obtain fluorinated polyether polyol.

9. The method for preparing a sweat-resistant PUR hot melt adhesive according to claim 7, characterized in that: When the hydroxy-terminated polybutadiene is modified hydroxy-terminated polybutadiene, the preparation steps are as follows: Weigh terminal hydroxyl polybutadiene and dichloromethane into a stirring kettle, stir to dissolve, add sodium hydroxide under nitrogen protection and stir for 20-30 minutes, add 1-chloro-2,4-dinitrobenzene into the stirring kettle, stir for 2-3 hours, and then react at room temperature for 10-12 hours, wash with anhydrous methanol and n-hexane, stand for separation, and obtain modified terminal hydroxyl polybutadiene after distillation.

Images