High-temperature-resistant hot melt adhesive film and preparation method thereof

Abstract

The application belongs to the technical field of adhesives, and relates to a high-temperature-resistant hot melt adhesive film and a preparation method thereof.The high-temperature-resistant hot melt adhesive film comprises the following raw material components in parts by weight: polybutylene adipate glycol 60-80 parts, diphenyl methane diisocyanate 25-40 parts, chain extender 3-6 parts, 2,2-difluoroethyl-2-hydroxybenzoate 1-2 parts, and antioxidant 0.3-0.8 parts.The chain extender is obtained by the reaction of dehydroascorbic acid and 3,5-dimethoxyphenol, and can improve the stability of the hot melt adhesive film in a high-temperature environment.The 2,2-difluoroethyl-2-hydroxybenzoate is obtained by the reaction of salicylic acid and 2,2-difluoroethanol, and can enhance the bonding strength between the hot melt adhesive film and a textile fabric.The preparation method is simple in process, is suitable for industrialized production, and expands the application of the hot melt adhesive film to various textile fabrics such as shoe materials, clothes, and bags.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of adhesives, and particularly relates to a high-temperature-resistant hot melt adhesive film and a preparation method thereof. BACKGROUND

[0002] Hot melt adhesive is a thermoplastic adhesive, which is solid at room temperature, melts and flows after heating, solidifies after cooling, and has an unchanged chemical structure, and is widely used in shoe materials, clothing, luggage and various textile fabrics. Common resin systems on the market include ethylene-vinyl acetate copolymer EVA, polyamide PA, copolyester PET / PES, polyethylene PE and polyurethane PU / TPU, and product forms include hot melt adhesive particles, adhesive powder, adhesive sticks and adhesive films. Among them, the hot melt adhesive film is preformed into a film, and only simple hot pressing is needed to complete the bonding, without the need for complex equipment, with zero volatile organic compound (VOC) emission in the whole process, and with precise and uniform adhesive amount, the hot melt adhesive film is widely used and becomes the preferred solution for modern efficient, precise and green manufacturing.

[0003] The bonding strength of hot melt adhesive is usually weaker than that of other adhesives such as epoxy resin or cyanoacrylate, and the bonding strength will be weakened when subjected to shear force or peeling force. At the same time, most hot melt adhesives are thermoplastic materials, and when the ambient temperature is close to or higher than the softening point, melting and flowing or creep phenomenon will occur. For example, the softening point of hot melt adhesive made of common thermoplastic resin (such as EVA) is generally not higher than 100 DEG C, which is not suitable for use in high-temperature and long-time use environment. Therefore, for high-temperature environment or long-time high-temperature environment, the high-temperature resistance of hot melt adhesive film still needs to be researched to enable the hot melt adhesive film to maintain stable bonding strength in high-temperature environment. SUMMARY

[0004] In order to overcome the shortcomings of the prior art, one of the purposes of the present application is to provide a high-temperature-resistant hot melt adhesive film.

[0005] The second purpose of the present application is to provide a preparation method of the high-temperature-resistant hot melt adhesive film.

[0006] In order to achieve the above-mentioned purposes, the present application adopts the following technical solutions:

[0007] The present application provides a high-temperature-resistant hot melt adhesive film, which comprises the following raw material components in parts by weight: polybutylene adipate glycol 60-80 parts, diphenyl methane diisocyanate 25-40 parts, chain extender 3-6 parts, 2,2-difluoroethyl-2-hydroxybenzoate 1-2 parts, antioxidant 0.3-0.8 parts; the chemical structural formula of the chain extender is:

[0008] .

[0009] Preferably, the preparation method of the chain extender comprises the following steps: adding dehydroascorbic acid into tetrahydrofuran, stirring uniformly, then adding 3,5-dimethoxyphenol and glacial acetic acid, stirring and reacting, and then concentrating under reduced pressure and purifying to obtain the product.

[0010] Preferably, the ratio of the amounts of dehydroascorbic acid, tetrahydrofuran, 3,5-dimethoxyphenol and glacial acetic acid is 10 mmol: 50 mL: 15-18 mmol: 18-20 mL.

[0011] Preferably, the stirring and reaction time is 8-10 h.

[0012] Preferably, the preparation method of 2,2-difluoroethyl-2-hydroxybenzoate comprises the following steps: adding salicylic acid into anhydrous N,N-dimethylformamide, then adding 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 4-dimethylaminopyridine and 2,2-difluoroethanol, reacting at room temperature, and then concentrating under reduced pressure and purifying to obtain the product.

[0013] Preferably, the ratio of the amounts of salicylic acid, anhydrous N,N-dimethylformamide, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 4-dimethylaminopyridine and 2,2-difluoroethanol is 20 mmol: 50 mL: 30-35 mmol: 10-12 mmol: 25-30 mmol.

[0014] Preferably, the reaction time is 16-24 h.

[0015] Preferably, the molecular weight of the polybutylene adipate glycol is 1000-2000 g / mol; and the antioxidant is antioxidant 1076 or antioxidant 168.

[0016] The application provides a preparation method of the high-temperature-resistant hot melt adhesive film, which comprises the following steps: weighing each raw material component according to a proportion, mixing, melt extruding, granulating, casting and shaping to obtain the product.

[0017] Preferably, the melt extruding temperature is 150-200 DEG C; and the thickness of the obtained high-temperature-resistant hot melt adhesive film is 0.05-0.5 mm.

[0018] Compared with the prior art, the application has the following beneficial effects:

[0019] The application provides a high-temperature-resistant hot melt adhesive film, and a chain extender in a raw material composition is obtained by reaction of dehydroascorbic acid and 3,5-dimethoxyphenol, wherein a rigid aromatic ring structure and symmetrical dimethoxy are introduced, a conjugated system is formed with dehydroascorbic acid, the system contains multiple reactive sites, and a three-dimensional crosslinking network can be formed when the system is crosslinked with polymer chains in the hot melt adhesive, thereby effectively limiting the movement of the polymer chains, reducing thermal degradation and flow of the hot melt adhesive film at high temperatures, and improving the stability of the hot melt adhesive film in a high-temperature environment. Meanwhile, the increase of crosslinking points increases the crosslinking density, and the introduction of methoxy can further improve the thermal decomposition temperature of the reaction product, thereby improving the mechanical properties and heat resistance of the hot melt adhesive film, so that the hot melt adhesive film is not easy to decompose in a high-temperature environment and still maintains good performance.

[0020] In the raw material composition of the application, 2,2-difluoroethyl-2-hydroxybenzoate is obtained by reaction of salicylic acid and 2,2-difluoroethanol, wherein a polar group can form a strong hydrogen bond network with a polar group on the surface of a textile fabric, thereby significantly enhancing the adhesion between the hot melt adhesive film and the textile fabric. Meanwhile, the hydrophobicity of the fluorine atom helps the hot melt adhesive film to better penetrate the microporous structure of the textile fabric, realize closer interfacial contact, and further enhance the adhesion. Furthermore, the introduction of the fluorine atom in 2,2-difluoroethanol can significantly improve the thermal stability of the product, so that the product is not easy to decompose in a high-temperature environment, thereby improving the heat resistance of the hot melt adhesive film. In addition, salicylic acid itself has certain antioxidant and light stability, and the introduction of 2,2-difluoroethanol can further enhance the antioxidant and light stability, and the presence of the fluorine atom can absorb more ultraviolet rays, thereby more effectively preventing the hot melt adhesive film from being degraded due to ultraviolet irradiation.

[0021] The application provides a preparation method of the high-temperature-resistant hot melt adhesive film, which is simple in process and suitable for industrial production, and expands the application of the hot melt adhesive film in various textile fabrics such as shoe materials, clothing, and bags. DETAILED DESCRIPTION

[0022] The application will be further described below in combination with specific embodiments. It should be noted that, under the premise of no conflict, the embodiments described below or the technical features between the embodiments can be combined in any manner to form new embodiments. The specific conditions not mentioned in the embodiments are carried out according to conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used, such as the conventional products obtained through the market channel, are not specifically mentioned.

[0023] Example 1

[0024] The embodiment provides a high-temperature-resistant hot melt adhesive film, which comprises the following raw material components in parts by weight: polybutylene adipate glycol (molecular weight is 1000 g / mol) 70 parts, diphenyl methane diisocyanate 30 parts, chain extender 5 parts, 2,2-difluoroethyl-2-hydroxybenzoate 1.5 parts, antioxidant (antioxidant 1076) 0.5 parts.

[0025] The preparation method of the chain extender in the embodiment comprises the following steps:

[0026]

[0027] Dehydroascorbic acid is added into tetrahydrofuran, and then 3,5-dimethoxyphenol and glacial acetic acid are added after stirring, wherein the amount ratio of dehydroascorbic acid, tetrahydrofuran, 3,5-dimethoxyphenol and glacial acetic acid is 10 mmol:50 mL:16 mmol:19 mL; the obtained solution is stirred for 9 h, and the reaction mixture is concentrated under reduced pressure and purified by flash silica gel column chromatography (V 正己烷 :V 乙酸乙酯 =1:1), to obtain the chain extender. The obtained chain extender has the following properties: 1 H NMR (400 MHz, DMSO-d6): 7.86(s, 1H), 6.31 (s, 2H), 4.73 (d, 1H), 4.36 (s, 1H), 4.20 (s, 1H), 4.10 (q,1H), 3.96 (s, 1H), 3.82 (s, 3H), 3.73 (s, 3H), 3.60-3.54 (m, 2H);HRMS-ESI (m / z):[M+H] + calcd for C 14 H 16 O9, 327.08; found, 327.08.

[0028] The preparation method of 2,2-difluoroethyl-2-hydroxybenzoate in the embodiment comprises the following steps:

[0029]

[0030] The salicylic acid is added to anhydrous N,N-dimethylformamide, and then 1-(3- dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 4-dimethylaminopyridine and 2,2- difluoroethanol are added, wherein the amount ratio of salicylic acid, anhydrous N,N- dimethylformamide, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 4- dimethylaminopyridine and 2,2-difluoroethanol is 20 mmol: 50 mL: 32 mmol: 11 mmol: 28 mmol; the reaction is carried out at room temperature for 20 h; the obtained mixture is extracted with ethyl acetate, the organic phases are combined, washed with saturated brine three times, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure; the crude product is purified by silica gel column chromatography (V 二氯甲烷 : V 甲醇 = 50: 1) to obtain 2,2-difluoroethyl-2-hydroxybenzoate. The obtained 2,2-difluoroethyl-2- hydroxybenzoate has the following structure: 1 H NMR (400 MHz, DMSO-d6): 15.1 (s, 1H), 7.85 (d, 1H), 7.47 (t,1H), 6.70 (d, 1H), 6.89 (s, 1H), 5.78-5.75 (m, 1H), 4.63 (td, 2H); HRMS-ESI (m / z): [M+H] + calcd for C9H8F2O3, 203.04; found, 203.05.

[0031] The preparation method of the high-temperature resistant hot melt adhesive film in this embodiment is as follows: the raw material components are weighed according to the proportion, mixed, melted and extruded at 180°C, and then granulated, cast and shaped to obtain the high-temperature resistant hot melt adhesive film. The thickness of the obtained high-temperature resistant hot melt adhesive film is 0.1 mm.

[0032] Example 2

[0033] The high-temperature resistant hot melt adhesive film provided in this embodiment comprises the following raw material components in parts by weight: polybutylene adipate glycol (molecular weight 2000 g / mol) 80 parts, diphenyl methane diisocyanate 40 parts, chain extender 6 parts, 2,2-difluoroethyl-2-hydroxybenzoate 2 parts, antioxidant (antioxidant 168) 0.8 parts.

[0034] The preparation method of the chain extender in this embodiment comprises the following steps: dehydroascorbic acid is added to tetrahydrofuran, and then 3,5-dimethoxyphenol is added after stirring to uniformity, and then glacial acetic acid is added, wherein the amount ratio of dehydroascorbic acid, tetrahydrofuran, 3,5-dimethoxyphenol and glacial acetic acid is 10 mmol: 50 mL: 18 mmol: 20 mL; the obtained solution is stirred to react for 10 h, the reaction mixture is concentrated under reduced pressure, and the product is purified by flash silica gel column chromatography (V 正己烷 : V乙酸乙酯 = 1 : 1) purification, to obtain the chain extender. The chain extender obtained has 1 H NMR is the same as that of Example 1.

[0035] The preparation method of 2,2-difluoroethyl-2-hydroxybenzoate in the embodiment comprises the following steps: salicylic acid is added into anhydrous N,N-dimethylformamide, and then 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride, 4-dimethylaminopyridine and 2,2-difluoroethanol are added, wherein the amount ratio of salicylic acid, anhydrous N,N-dimethylformamide, 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride, 4-dimethylaminopyridine and 2,2-difluoroethanol is 20 mmol: 50 mL: 35 mmol: 12 mmol: 30 mmol; the reaction is carried out at room temperature for 24 h; the obtained mixture is extracted with ethyl acetate, the organic phases are combined, washed with saturated brine for three times, dried with anhydrous sodium sulfate, filtered and concentrated under reduced pressure; the crude product is subjected to silica gel column chromatography (V 二氯甲烷 : V 甲醇 = 1 : 1) purification, to obtain 2,2-difluoroethyl-2-hydroxybenzoate. The 2,2-difluoroethyl-2-hydroxybenzoate obtained has 1 H NMR is the same as that of Example 1.

[0036] The preparation method of the high-temperature-resistant hot melt adhesive film in the embodiment is as follows: the raw material components are weighed according to the proportion, mixed, melt-extruded at 200°C, granulated, cast and shaped, and then obtained. The thickness of the obtained high-temperature-resistant hot melt adhesive film is 0.1 mm.

[0037] Example 3

[0038] The embodiment provides a high-temperature-resistant hot melt adhesive film, which comprises the following raw material components in parts by weight: polybutylene adipate glycol (molecular weight is 1000 g / mol) 60 parts, diphenyl methane diisocyanate 25 parts, chain extender 3 parts, 2,2-difluoroethyl-2-hydroxybenzoate 1 part and antioxidant (antioxidant 1076) 0.3 part.

[0039] The preparation method of the chain extender in the embodiment comprises the following steps: dehydroascorbic acid is added into tetrahydrofuran, 3,5-dimethoxyphenol is added after stirring uniformly, and glacial acetic acid is added, wherein the amount ratio of dehydroascorbic acid, tetrahydrofuran, 3,5-dimethoxyphenol and glacial acetic acid is 10 mmol: 50 mL: 15 mmol: 18 mL; the obtained solution is stirred for 8 h, the reaction mixture is concentrated under reduced pressure, and the product is subjected to rapid silica gel column chromatography (V 正己烷 : V 乙酸乙酯 = 1 : 1) purification, to obtain the chain extender. The chain extender obtained has 1 H NMR is the same as that of Example 1.

[0040] The preparation method of 2,2-difluoroethyl-2-hydroxybenzoate in the embodiment comprises the following steps: salicylic acid is added into anhydrous N,N-dimethylformamide, and then 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 4-dimethylaminopyridine and 2,2-difluoroethanol are added, wherein the amount ratio of salicylic acid, anhydrous N,N-dimethylformamide, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 4-dimethylaminopyridine and 2,2-difluoroethanol is 20 mmol: 50 mL: 30 mmol: 10 mmol: 25 mmol; the reaction is carried out at room temperature for 16 h; the obtained mixture is extracted with ethyl acetate, the organic phases are combined, washed with saturated brine for three times, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure; the crude product is purified by silica gel column chromatography (V 二氯甲烷 :V 甲醇 = 50:1) to obtain 2,2-difluoroethyl-2-hydroxybenzoate. 1 The HNMR of the obtained 2,2-difluoroethyl-2-hydroxybenzoate is the same as that of Example 1.

[0041] The preparation method of the high-temperature-resistant hot melt adhesive film in the embodiment is as follows: the raw material components are weighed according to the proportion, mixed, melt-extruded at 150 ℃, granulated, cast and shaped to obtain the high-temperature-resistant hot melt adhesive film. The thickness of the obtained high-temperature-resistant hot melt adhesive film is 0.1 mm.

[0042] Comparative Example 1

[0043] The difference between the comparative example and Example 1 is that the chain extender is replaced by ascorbic acid.

[0044] Comparative Example 2

[0045] The difference between the comparative example and Example 1 is that 2,2-difluoroethyl-2-hydroxybenzoate is replaced by methyl salicylate.

[0046] Test Example

[0047] 1. According to GB / T2792-2014 “180° Peeling Strength Test Method of Pressure Sensitive Adhesive Tape”, the high-temperature-resistant hot melt adhesive films obtained in Examples 1-3 and Comparative Examples 1-2 are respectively hot-pressed with nylon mesh cloth (160 ℃, 5 min) to determine the peeling strength, and the results are shown in Table 1.

[0048] 2. The loop softening point of the high-temperature-resistant hot melt adhesive films obtained in Examples 1-3 and Comparative Examples 1-2 is tested according to ASTM D6493, and the results are shown in Table 1.

[0049] 3. The high-temperature resistant hot melt adhesive films obtained in Examples 1-3 and Comparative Example 1-2 were respectively hot-pressed with nylon mesh (160℃, 5min), and then placed in an aging oven (85℃, 85% RH) for 168h. The adhesive opening and yellowing were observed after taking out, and the results are shown in Table 1.

[0050] 4. The high-temperature resistant hot melt adhesive films obtained in Examples 1-3 and Comparative Example 1-2 were subjected to QUV yellowing resistance test according to GB / T 16422.3-2022 "Plastics - Laboratory light source exposure test methods - Part 3: Fluorescent UV lamps", and the results are shown in Table 1.

[0051] Table 1

[0052]

[0053] According to Table 1, the adhesion performance, thermal stability and photo-oxidation of the high-temperature resistant hot melt adhesive films obtained in Examples 1-3 are all better than those of Comparative Example 1-2. Specifically, the chain extender of the present application is obtained by reacting dehydroascorbic acid with 3,5-dimethoxyphenol, which introduces rigid aromatic ring structure and symmetrical dimethoxy group, forms a conjugated system with dehydroascorbic acid, and can form a three-dimensional crosslinked network when crosslinking with the polymer chains in the hot melt adhesive, thereby improving the stability of the hot melt adhesive film in high temperature environment. The 2,2-difluoroethyl-2-hydroxybenzoate obtained by reacting salicylic acid and 2,2-difluoroethanol can form a strong hydrogen bond network with the polar groups on the surface of the textile fabric, and the hydrophobicity of the fluorine atom helps the hot melt adhesive film to better penetrate the microporous structure of the textile fabric, realizing closer interfacial contact, thereby significantly enhancing the bonding strength between the hot melt adhesive film and the textile fabric.

[0054] The above embodiments are only preferred embodiments of the present application, and cannot be used to limit the scope of protection of the present application. Any non-essential changes and substitutions made by those skilled in the art based on the present application are within the scope of the present application.

Claims

1. A high temperature resistant hot melt adhesive film, characterized by, By weight parts, including the following raw material components: polybutylene adipate glycol 60-80 parts, diphenyl methane diisocyanate 25-40 parts, chain extender 3-6 parts, 2, 2-difluoroethyl-2-hydroxybenzoic acid 1-2 parts, antioxidant 0.3-0.8 parts; the chemical structural formula of the chain extender is: 。 2. The high temperature resistant hot melt adhesive film according to claim 1, characterized in that, The preparation method of the chain extender comprises the following steps: adding dehydroascorbic acid into tetrahydrofuran, stirring uniformly, then adding 3, 5-dimethoxyphenol, glacial acetic acid, stirring and reacting, and then concentrating under reduced pressure and purifying to obtain.

3. The high temperature resistant hot melt adhesive film according to claim 2, characterized in that, The amount ratio of the dehydroascorbic acid, tetrahydrofuran, 3, 5-dimethoxyphenol and glacial acetic acid is 10 mmol: 50 mL: 15-18 mmol: 18-20 mL.

4. The high temperature resistant hot melt adhesive film according to claim 2, wherein, The stirring and reaction time is 8-10 h.

5. The high temperature resistant hot melt adhesive film according to claim 1, wherein, The preparation method of the 2, 2-difluoroethyl-2-hydroxybenzoate comprises the following steps: adding salicylic acid into anhydrous N, N-dimethylformamide, then adding 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride, 4-dimethylaminopyridine and 2, 2-difluoroethanol, reacting at room temperature, and then concentrating under reduced pressure and purifying to obtain.

6. The high temperature resistant hot melt adhesive film according to claim 5, wherein, The amount ratio of the salicylic acid, anhydrous N, N-dimethylformamide, 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride, 4-dimethylaminopyridine and 2, 2-difluoroethanol is 20 mmol: 50 mL: 30-35 mmol: 10-12 mmol: 25-30 mmol.

7. The high temperature resistant hot melt adhesive film according to claim 5, wherein, The reaction time is 16-24 h.

8. The high temperature resistant hot melt adhesive film according to claim 1, wherein, The molecular weight of the polybutylene adipate glycol is 1000-2000 g / mol; and the antioxidant is antioxidant 1076 or antioxidant 168.

9. The method of claim 1-8, wherein the method further comprises the step of, The preparation method is as follows: weighing each raw material component according to the proportion, mixing, melt extruding, granulating, casting, and shaping to obtain.

10. The method for preparing the high-temperature resistant hot melt adhesive film according to claim 9, characterized in that, The melt extrusion temperature is 150-200 DEG C; and the thickness of the obtained high-temperature-resistant hot melt adhesive film is 0.05-0.5 mm.

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