Vegetable oil-based polyamide adhesive and preparation method thereof

Abstract

The invention belongs to the technical field of bio-based high polymer materials, and particularly relates to a vegetable oil-based polyamide adhesive and a preparation method thereof. And carrying out melt polycondensation reaction on the long-carbon-chain unsaturated aliphatic dicarboxylic acid and polyamine to obtain the plant oil-based polyamide adhesive. The fluorescent flame-retardant water-resistant plastic has the advantages of fluorescence characteristic, flame retardant property and excellent water resistance, and the mechanical property is obviously improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of bio-based polymer materials, and in particular relates to a plant oil-based polyamide adhesive and a preparation method thereof. Background Art

[0002] Adhesives have a wide range of applications and are frequently used in industries such as construction, automotive manufacturing, aviation, shipbuilding, electronic equipment, healthcare, and wood manufacturing. Currently, most common adhesives are formaldehyde-based resin adhesives, which release carcinogens such as formaldehyde during use, posing a serious threat to human health and the environment. Therefore, there is an urgent need for new, green and environmentally friendly adhesives to fill this market gap. In recent years, with the scarcity of natural resources and growing environmental awareness, bio-based materials have attracted considerable attention as a green, renewable alternative. Bio-based polyamide adhesives, as a bio-based material, are becoming a new force in the adhesive market due to their excellent performance and broad application prospects. Bio-based polyamide adhesives are polymer adhesives made from renewable biomass resources through biological or chemical methods. They retain the excellent physical and chemical properties of traditional polyamide adhesives while also possessing environmentally friendly properties such as biodegradability and renewability. The preparation process of bio-based polyamide adhesives primarily involves three steps: raw material selection, polymerization reaction, and post-processing. The polymerization reaction involves controlling reaction conditions to cause the amide groups in the raw materials to undergo polymerization to form a high-molecular-weight polymer. Post-processing includes purification and drying to produce a bio-based polyamide adhesive with stable performance. Excellent physical properties: Bio-based polyamide adhesives exhibit high adhesion, temperature resistance, abrasion resistance, and chemical resistance, meeting the requirements of use in a variety of complex environments. Environmental friendliness: Bio-based polyamide adhesives are made from renewable biomass resources and exhibit good biodegradability, meeting environmental requirements. Renewability: The raw materials for bio-based polyamide adhesives are derived from renewable resources, enabling resource recycling and reducing environmental impact. Bio-based polyamide adhesives have been widely used in various fields due to their unique performance advantages. Further development of new specialty adhesives based on bio-based adhesives is particularly important, as they can make adhesives suitable for even more demanding environments.

[0003] Chinese patent CN 106750264 A discloses a bio-based long-chain polyamide and its synthesis method. Bio-based 1,9-azelaic acid and 1,12-dodecanediamine, prepared from renewable plant oils, are used as monomers to synthesize bio-based polyazelazoyl dodecanediamine (PA129) through a direct melt polycondensation reaction under normal pressure. First, although the PA129 synthesized in this patent has a longer carbon chain than other common polyamides, its melting temperature is approximately 195°C, and its heat resistance is still poor compared to high-performance engineering plastics. Second, while PA129 has a certain degree of water resistance, it still suffers from a short lifespan in humid environments. Finally, the lack of flame retardancy in PA129 greatly limits its application areas. Summary of the Invention

[0004] The purpose of the present invention is to provide a vegetable oil-based polyamide adhesive having fluorescent properties and flame retardant properties, excellent water resistance, and significantly improved mechanical properties; the present invention also provides a preparation method of the vegetable oil-based polyamide adhesive.

[0005] The plant oil-based polyamide adhesive of the present invention has the following structural formula:

[0006] Where m2 = 3-11.

[0007] The preparation method of the vegetable oil-based polyamide adhesive of the present invention is to carry out melt polycondensation reaction of long carbon chain unsaturated fatty dicarboxylic acid and polyamine to obtain the vegetable oil-based polyamide adhesive.

[0008] The structural formula of long carbon chain unsaturated fatty dicarboxylic acid is as follows:

[0009] Where m2 = 3-11.

[0010] The long carbon chain unsaturated fatty dicarboxylic acid is one of octadec-9-enedioic acid, eicos-10-enedioic acid, hexacos-13-enedioic acid or deca-5-enedioic acid.

[0011] Long-chain unsaturated fatty dicarboxylic acids are prepared by olefin metathesis reaction of unsaturated fatty acids.

[0012] The unsaturated fatty acid is one of 10-undecenoic acid, oleic acid, ricinoleic acid, linoleic acid, linolenic acid, arachidonic acid or erucic acid.

[0013] Unsaturated fatty acids are obtained by cracking vegetable oils.

[0014] The polyamine is 1,3-bis(3-aminopropyl)tetramethyldisiloxane.

[0015] The molar ratio of the long carbon chain unsaturated fatty dicarboxylic acid to the polyamine is 1:0.5-2.

[0016] The temperature of the melt polycondensation reaction is 160-260° C., and the time of the melt polycondensation reaction is 4-6 hours.

[0017] The reaction equation for preparing the long carbon chain unsaturated fatty dicarboxylic acid of the present invention is as follows:

[0018] In formulas Ⅰ-Ⅴ, m1=0-7, m2=3-11.

[0019] The structural formula of Grubbs 2nd catalyst is as follows: .

[0020] When m1=7 and m2=7 in formula I, octadec-9-enedioic acid is obtained by metathesis of oleic acid; when m1=7 and m2=11 in formula I, hexadec-13-enedioic acid is obtained by metathesis of erucic acid; when m1=4 and m2=7 in formula II, octadec-9-enedioic acid is obtained by metathesis of linoleic acid; when m1=4 and m2=3 in formula III, dec-5-enedioic acid is obtained by metathesis of arachidonic acid; when m2=8 in formula IV, eicosapentaenoic acid is obtained by metathesis of 10-undecenoic acid; when m1=5 and m2=7 in formula V, octadec-9-enedioic acid is obtained by metathesis of ricinoleic acid.

[0021] Reaction equation of the present invention is as follows:

[0022] Where m2 = 3-11.

[0023] The beneficial effects of the present invention are as follows: The invention uses a long carbon chain unsaturated fatty dicarboxylic acid prepared by olefin metathesis reaction of unsaturated fatty acids in vegetable oil and a polyamine containing Si-O-Si groups to prepare a vegetable oil-based polyamide adhesive with fluorescent characteristics and flame retardant properties.

[0024] The raw materials used in the vegetable oil-based polyamide adhesive of the present invention all come from vegetable oil, and have the advantages of being green, environmentally friendly, pollution-free, and sustainable. It is expected to solve the problems that the synthesis of traditional adhesive materials generally relies on formaldehyde, and the release of formaldehyde during use seriously endangers human health.

[0025] The raw materials used in the present invention are abundant, low-priced and renewable vegetable oils, which give the polyamide adhesive good biodegradability; and the long-chain unsaturated fatty dicarboxylic acids obtained by cracking the vegetable oil give the polyamide good flexibility and softness, which allows the adhesive to adapt to certain external force impacts after curing, reduces the cracking of the adhesive layer caused by stress, and greatly improves the impact resistance of the adhesive.

[0026] This study successfully developed a multifunctional polyamide adhesive through molecular structural design, whose performance advantages stem from a unique molecular structure-activity relationship. The introduction of long-chain unsaturated fatty dicarboxylic acids reduces the density of amide groups, achieving a dual effect: Firstly, the dense hydrophobic layer (a network structure formed by cross-linking multiple siloxane (Si-O-Si) groups) imparts excellent water resistance (contact angle >100°) to the vegetable oil-based polyamide adhesive. Secondly, the conjugated double bond system generates significant fluorescence (maximum emission wavelength 423nm) through an intramolecular charge transfer mechanism. Furthermore, the present invention constructs a multi-dimensional performance enhancement system through the grafting modification of siloxane groups (Si-O-Si): ① In terms of thermal stability, the high bond energy siloxane bond (452kJ / mol) increases the thermal decomposition temperature of the material to above 380°C; ② In terms of mechanical properties, the dynamic siloxane bonds on different chains form an interpenetrating network structure with the amide groups, and the tensile strength is significantly improved; ③ In terms of weather resistance, the UV shielding effect of siloxane can effectively extend the service life of the adhesive; ④ In terms of fluorescence enhancement, the steric protection of the unsaturated double bond chromophore by the rigid siloxane structure increases the quantum yield, effectively enhancing the fluorescence intensity of the polyamide adhesive; ⑤ Enhanced bonding strength: On the one hand, the polyamide The increase in the number of polar groups such as amino and carboxyl groups in the amide and the increase in the number of intermolecular hydrogen bonds increase the forces in the molecular chain, thereby increasing the viscosity of the polyamide adhesive. On the other hand, as the proportion of diamine monomers continues to increase, the content of Si-O-Si groups also increases. Si-O-Si groups have extremely high bond energy and can interact with polyamide molecular chains to form hydrogen bonds or chemical bonds, greatly increasing the degree of cross-linking of polyamide, thereby increasing the viscosity of polyamide. ⑥ Flame retardancy: The bond energy of Si-O-Si groups in vegetable oil-based polyamide adhesives is higher and more stable than CC bonds, which can effectively delay the decomposition of polyamide at high temperatures. The present invention achieves the synergistic optimization of bonding strength, hydrophobicity, flame retardancy and fluorescence properties, and shows important application prospects in the fields of flexible electronic packaging and smart sensor coatings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the H NMR spectrum of eicosapentaenoic acid obtained in Example 1.

[0028] Figure 2 This is the C NMR spectrum of eicosapentaenoic acid obtained in Example 1.

[0029] Figure 3 This is the nuclear magnetic hydrogen spectrum of the vegetable oil-based polyamide adhesive prepared in Example 1.

[0030] Figure 4 This is the H NMR spectrum of octadec-9-enedioic acid obtained in Example 5.

[0031] Figure 5 This is the C NMR spectrum of octadec-9-enedioic acid obtained in Example 5.

[0032] Figure 6 This is the H-NMR spectrum of the vegetable oil-based polyamide adhesive prepared in Example 5.

[0033] Figure 7 This is the infrared analysis result of C20-PA1, C20-PA2, C20-PA3 and C20-PA4.

[0034] Figure 8 This is the infrared analysis result of C18-PA1, C18-PA2, C18-PA3 and C18-PA4.

[0035] Figure 9 This is the thermogravimetric analysis results of C20-PA1, C20-PA2, C20-PA3 and C20-PA4.

[0036] Figure 10 This is the thermogravimetric analysis result of C18-PA1, C18-PA2, C18-PA3 and C18-PA4.

[0037] Figure 11 It is the differential scanning calorimetry results of C20-PA1, C20-PA2, C20-PA3 and C20-PA4.

[0038] Figure 12 It is the differential scanning calorimetry results of C18-PA1, C18-PA2, C18-PA3 and C18-PA4.

[0039] Figure 13 This is the shear strength analysis result graph of C20-PA1, C20-PA2, C20-PA3 and C20-PA4.

[0040] Figure 14 This is the shear strength analysis result graph of C18-PA1, C18-PA2, C18-PA3 and C18-PA4.

[0041] Figure 15These are the water contact angle analysis results of C20-PA2 and C18-PA2. In the figure, a is the water contact angle analysis result of C20-PA2, and b is the water contact angle analysis result of C18-PA2.

[0042] Figure 16 This is a physical picture of the vertical combustion test. In the picture, a is the physical picture of the long strip sample before combustion, and b is the physical picture of the long strip sample after combustion.

[0043] Figure 17 1 is a fluorescence intensity detection curve diagram of Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0044] The present invention is further described below with reference to the following examples.

[0045] Example 1 446 mg of Grubbs 2nd catalyst was added to a three-necked flask and purged with nitrogen three times. Then, 27.86 ml of 10-undecenoic acid was added under nitrogen flow and reacted at 48°C for 4 hours. After completion of the reaction, a brown solid, i.e., a crude product, was obtained. The crude product was added to methanol / ethyl acetate for recrystallization to obtain a white solid. The obtained white solid was dried in a vacuum drying oven at 60°C for 24 hours to remove the residual solvent to obtain eicosapentaenoic acid. The H NMR spectrum is shown in FIG. Figure 1 , NMR carbon spectrum see Figure 2 .

[0046] 8 mmol of eicosapentaenoic acid and 4 mmol of 1,3-bis(3-aminopropyl)tetramethyldisiloxane were added to a three-necked flask. The metal bath was preheated to 160°C in advance. After reaching the temperature, the three-necked flask was added to the metal bath. Nitrogen was then passed through the three-necked flask to ensure that the reaction mixture was in a nitrogen atmosphere. After all the solids melted, stirring was started and the mixture was gradually heated to 260°C. The heating process was controlled within 4 hours. The pressure was reduced by a vacuum pump to remove excess water. The reaction was continued for 2 hours to obtain a vegetable oil-based polyamide adhesive named C20-PA1. The H NMR spectrum is shown in FIG. Figure 3 .

[0047] The reaction equation is as follows:

[0048] Example 2 8 mmol of eicosapentaenoic acid and 8 mmol of 1,3-bis(3-aminopropyl)tetramethyldisiloxane were added to a three-necked flask. The metal bath was preheated to 160°C in advance. After reaching the temperature, the three-necked flask was added to the metal bath. Nitrogen was then passed through the three-necked flask to ensure that the reaction mixture was in a nitrogen atmosphere. After all the solids melted, stirring was started and the mixture was gradually heated to 260°C. The heating process was controlled within 2 hours. The pressure was reduced with a vacuum pump to remove excess water. The reaction was continued for 2 hours to obtain a vegetable oil-based polyamide adhesive, named C20-PA2.

[0049] Example 3 8 mmol of eicosapentaenoic acid was added to a three-necked flask, followed by 12 mmol of 1,3-bis(3-aminopropyl)tetramethyldisiloxane. The metal bath was preheated to 160°C in advance. After reaching the temperature, the three-necked flask was added to the metal bath. Nitrogen was then passed through the three-necked flask to ensure that the reaction mixture was in a nitrogen atmosphere. After all the solids melted, stirring was started and the mixture was gradually heated to 260°C. The heating process was controlled within 3 hours. The pressure was reduced using a vacuum pump to remove excess water. The reaction was continued for 2 hours to obtain a vegetable oil-based polyamide adhesive, named C20-PA3.

[0050] Example 4 8 mmol of eicosapentaenoic acid was added to a three-necked flask, followed by 16 mmol of 1,3-bis(3-aminopropyl)tetramethyldisiloxane. The metal bath was preheated to 160°C in advance. After reaching the temperature, the three-necked flask was added to the metal bath. Nitrogen was then passed through the three-necked flask to ensure that the reaction mixture was in a nitrogen atmosphere. After all the solids melted, stirring was started and the mixture was gradually heated to 260°C. The heating process was controlled within 4 hours. The pressure was reduced with a vacuum pump to remove excess water. The reaction was continued for 2 hours to obtain a vegetable oil-based polyamide adhesive, named C20-PA4.

[0051] Example 5 446 mg of Grubbs 2nd catalyst was added to a three-necked flask and purged with nitrogen three times. Then, 47.61 ml of oleic acid was added under nitrogen flow and reacted at 48°C for 4 hours. After the reaction was completed, a brown solid, i.e., a crude product, was obtained. The crude product was added to methanol / ethyl acetate for recrystallization to obtain a white solid. The obtained white solid was dried in a vacuum drying oven at 60°C for 24 hours to remove the residual solvent to obtain octadec-9-enedioic acid. The H NMR spectrum is shown in FIG. Figure 4 , NMR carbon spectrum see Figure 5 .

[0052] 8 mmol of octadec-9-enedioic acid and 4 mmol of 1,3-bis(3-aminopropyl)tetramethyldisiloxane were added to a three-necked flask. The metal bath was preheated to 160°C in advance. After reaching the temperature, the three-necked flask was added to the metal bath. Nitrogen was then passed through the three-necked flask to ensure that the reaction mixture was in a nitrogen atmosphere. After all the solids melted, stirring was started and the mixture was gradually heated to 260°C. The heating process was controlled within 4 hours. The pressure was reduced by a vacuum pump to remove excess water. The reaction was continued for 2 hours to obtain a vegetable oil-based polyamide adhesive named C18-PA1. The H NMR spectrum is shown in FIG. Figure 6 .

[0053] The reaction equation is as follows:

[0054] Example 6 8 mmol of octadec-9-enedioic acid and 8 mmol of 1,3-bis(3-aminopropyl)tetramethyldisiloxane were added to a three-necked flask. The metal bath was preheated to 160°C in advance. After reaching the temperature, the three-necked flask was added to the metal bath. Nitrogen was then flowed into the three-necked flask to ensure that the reaction mixture was in a nitrogen atmosphere. After all the solids melted, stirring was started and the mixture was gradually heated to 260°C. The heating process was controlled within 4 hours. The pressure was reduced with a vacuum pump to remove excess water. The reaction was continued for 2 hours to obtain a vegetable oil-based polyamide adhesive, named C18-PA2.

[0055] Example 7 8 mmol of octadec-9-enedioic acid and 12 mmol of 1,3-bis(3-aminopropyl)tetramethyldisiloxane were added to a three-necked flask. The metal bath was preheated to 160°C in advance. After reaching the temperature, the three-necked flask was added to the metal bath. Nitrogen was then flowed into the three-necked flask to ensure that the reaction mixture was in a nitrogen atmosphere. After all the solids melted, stirring was started and the mixture was gradually heated to 260°C. The heating process was controlled within 4 hours. The pressure was reduced with a vacuum pump to remove excess water. The reaction was continued for 2 hours to obtain a vegetable oil-based polyamide adhesive, named C18-PA3.

[0056] Example 8 8 mmol of octadec-9-enedioic acid and 16 mmol of 1,3-bis(3-aminopropyl)tetramethyldisiloxane were added to a three-necked flask. The metal bath was preheated to 160°C in advance. After reaching the temperature, the three-necked flask was added to the metal bath. Nitrogen was then flowed into the three-necked flask to ensure that the reaction mixture was in a nitrogen atmosphere. After all the solids melted, stirring was started and the mixture was gradually heated to 260°C. The heating process was controlled within 4 hours. The pressure was reduced with a vacuum pump to remove excess water. The reaction was continued for 2 hours to obtain a vegetable oil-based polyamide adhesive, named C18-PA4.

[0057] Comparative Example 1 1,3-bis(3-aminopropyl)tetramethyldisiloxane was replaced with 1,9-diaminononane, and other steps were the same as in Example 1.

[0058] The reaction equation is as follows:

[0059] Product testing: 1. Nuclear Magnetic Resonance Testing (NMR) The monomers and polymers were characterized using a Bruker Avance (III) HD 400 from Bruker, Switzerland, with tetramethylsilane (TMS) as the internal standard. Based on the solubility of the monomers and polymers, deuterated dimethyl sulfoxide (DMSO-d6) was used as the solvent for the monomers and deuterated trifluoroacetic acid (CF3COOD) was used as the solvent for the polymers. All tests required full dissolution.

[0060] 2. Fourier transform infrared spectroscopy (FT-IR) Fourier transform infrared spectroscopy was performed on a Shimadzu IRAffinity-1S infrared spectrometer. The test range was 4000-500 cm -1 Before the test, KBr was dried in an oven at 120°C for 4 hours. Since the prepared polymer had high adhesiveness and could not be ground into powder, hexafluoroisopropanol was used as solvent to dissolve the polyamide adhesive obtained in Example 1-8 in a vial. The polyamide adhesive was then dripped onto the pressed KBr tablet using a capillary tube for testing. The test results are shown in Figure 7 and Figure 8 .

[0061] 3. Thermogravimetric analysis (TG) The thermal stability of the polyamide adhesives prepared in Examples 1-8 was analyzed using a Swiss Mettler TGA / DSC1 thermogravimetric test. Due to the special properties of polyamide adhesives, they cannot be ground into powder. Therefore, the adhesive was prepared into a 10mm×10mm×2mm rectangular block using a polytetrafluoroethylene mold. After being fixed in a crucible, the temperature was increased at a rate of 5°C / min under a nitrogen atmosphere, and the temperature range was from room temperature to 600°C. The test results are shown in FIG. Figure 9 and Figure 10 .

[0062] 4. Differential Scanning Calorimetry (DSC) The glass transition temperature and melting point of the polyamide adhesives prepared in Examples 1-8 were tested using a Swiss Mettler DSC1. The test conditions were as follows: 5 mg of polyamide adhesive sample was weighed and placed in an aluminum crucible, ensuring that the sample was accurately distributed at the bottom of the crucible. Another empty aluminum crucible was used as a control group. The temperature was then gradually increased under a nitrogen atmosphere, and the data was recorded. The heating rate of the polyamide adhesive sample was 5°C / min, and the temperature range was 30-500°C. The test results are shown in Figure 2. Figure 11 and Figure 12 .

[0063] 5. Adhesion performance test The shear strength of an adhesive is a key indicator for determining whether its bonding performance meets standards. According to GB / T 7124-2008, wooden planks were cut using cutting tools to prepare the test specimens required for the experiment. The test specimens were 50 mm × 10 mm × 2 mm wooden strips. The polyamide adhesive prepared in Examples 1-8 was evenly applied to one end of the wooden strips. The two strips were then spliced together, with the bonding area between each pair of strips being 10 mm × 10 mm. After bonding, the two strips were pressed firmly for several seconds. The bonded samples were left to rest for 24 hours to eliminate internal stress, resulting in plywood specimens. Shear strength testing of the plywood specimens was performed using a Meters Industrial Systems CMT6103 universal testing machine. The testing method strictly complies with the Chinese national standard GB / T 7124-2008 (Determination of tensile shear strength of adhesives). Each set of plywood samples was tested in parallel, and the average shear strength value was used as the final result. To investigate the water resistance of the polyamide adhesive, a wet shear strength test was performed. Each group of plywood samples were immersed in cold water (20±3℃) for 24h and in hot water (60±3℃) for 6h. The samples were tested immediately after immersion. The test results are shown in Figure 13 and Figure 14 .

[0064] 6. Water contact angle test Water contact angle test is a common test method for the water resistance of materials. When the water contact angle is greater than 90°, the material is hydrophobic. When the water contact angle is less than 90°, the material is hydrophilic. Water contact angle tests were conducted on C20-PA2 and C18-PA2. The test results are shown in Figure 15 .

[0065] 7. Flame retardant performance test The vegetable oil-based polyamide adhesive prepared in Example 1 was tested using the vertical combustion method. The vegetable oil-based polyamide adhesive prepared in Example 1 was prepared into five strips of samples with a length of 130 mm, a width of 13 mm, and a thickness of 10 mm. The strips were then pretreated at 25°C and 50% humidity for 48 hours. Finally, the strips were tested on a British FTT0082 horizontal vertical combustion tester in accordance with GB / T2408. The test results are shown in Table 1. Figure 16 and Table 1.

[0066]

[0067] As shown in Table 1, the vegetable oil-based polyamide adhesive prepared in Example 1 exhibits flame retardancy, achieving a V-2 rating in the vertical combustion test. The flame retardancy of the vegetable oil-based polyamide adhesive is due to the presence of a large number of Si-O-Si groups in the polyamide adhesive. Si-O-Si groups have higher bond energies and are more stable than C-C bonds, effectively slowing the decomposition of the polyamide at high temperatures. During combustion, Si-O-Si groups decompose at high temperatures to form inorganic ceramic phases such as silicon dioxide and silicon carbide. Silicon dioxide and silicon carbide can form a dense, insulating layer on the surface of the polyamide material, effectively blocking heat transfer, oxygen diffusion, and the release of combustible volatile products. Furthermore, Si-O-Si groups decompose during combustion to form silicon-containing free radicals (e.g., Si· and SiO·). These free radicals can combine with active free radicals (e.g., H· and HO·) in the gas phase, effectively interrupting the combustion chain reaction. In summary, the flame retardant effect of Si-O-Si groups is a multi-dimensional, synergistic flame retardant effect.

[0068] 8. Fluorescence spectrophotometer test The polyamide adhesives of Example 1 and Comparative Example 1 were tested by fluorescence spectrophotometer, and the test curves are shown in FIG. Figure 17, Example 1 and Comparative Example 1 both have a certain fluorescence intensity due to the presence of unsaturated double bonds in the molecular chain, but the fluorescence intensity of Example 1 prepared by using 1,3-bis(3-aminopropyl)tetramethyldisiloxane is significantly better than that of Comparative Example 1 prepared by using 1,9-diaminononane without Si-O-Si groups. The main reason is that Si-O-Si is generally a non-fluorescent chromophore and does not have the ability to directly generate or enhance fluorescence, but the Si-O-Si group is the basic structural unit of siloxane, which has good stability, film-forming properties, and chemical inertness. When Si-O-Si groups are introduced into the polyamide molecular chain, it helps to construct a specific molecular structure, so that the fluorescent chromophore is in a more favorable microenvironment, reducing the fluorescence quenching factor, indirectly playing a certain stabilizing and protective role on the fluorescence, thereby showing a fluorescence enhancement effect to a certain extent; and the carbon-carbon double bond in the polyamide molecular chain interacts with the Si-O-Si group, and energy transfer occurs. The Si-O-Si group transfers energy to the carbon-carbon double bond, thereby enhancing fluorescence emission; on the other hand, the addition of the Si-O-Si group can reduce the crystallinity of the polyamide, reduce the fluorescence quenching caused by close stacking, thereby enhancing fluorescence. The adhesive with fluorescent properties prepared by the present invention is widely used. It can be used for emergency evacuation instructions and decoration in the field of construction and decoration. It can be used for electronic component packaging and electrical appliance housing decoration in the field of electronics and electrical appliances. It can be used for road signs and vehicle interiors in the field of transportation. The advertising and sign industry is used to make advertising signs and commercial signs. The safety and fire protection field is used for fire equipment and personal safety signs. In addition, in the manufacture of toys and handicrafts, it can also be used to paste luminous components and create artistic effects to meet the functional and aesthetic requirements of different scenes.

Claims

1. A vegetable oil-based polyamide adhesive, characterized in that The structural formula is as follows: Where m2 = 3-11.

2. A method for preparing the vegetable oil-based polyamide adhesive according to claim 1, characterized in that The long carbon chain unsaturated fatty dicarboxylic acid and polyamine undergo melt polycondensation reaction to obtain a vegetable oil-based polyamide adhesive.

3. The preparation method of the vegetable oil-based polyamide adhesive according to claim 2, characterized in that The structural formula of long carbon chain unsaturated fatty dicarboxylic acid is as follows: Where m2 = 3-11.

4. The method for preparing the vegetable oil-based polyamide adhesive according to claim 2, wherein The long carbon chain unsaturated fatty dicarboxylic acid is one of octadec-9-enedioic acid, eicos-10-enedioic acid, hexacos-13-enedioic acid or deca-5-enedioic acid.

5. The preparation method of the vegetable oil-based polyamide adhesive according to claim 2, characterized in that Long-chain unsaturated fatty dicarboxylic acids are prepared by olefin metathesis reaction of unsaturated fatty acids.

6. The method for preparing the vegetable oil-based polyamide adhesive according to claim 5, characterized in that The unsaturated fatty acid is one of 10-undecenoic acid, oleic acid, ricinoleic acid, linoleic acid, linolenic acid, arachidonic acid or erucic acid.

7. The method for preparing the vegetable oil-based polyamide adhesive according to claim 5, characterized in that Unsaturated fatty acids are obtained by cracking vegetable oils.

8. The method for preparing the vegetable oil-based polyamide adhesive according to claim 2, wherein The polyamine is 1,3-bis(3-aminopropyl)tetramethyldisiloxane.

9. The method for preparing the vegetable oil-based polyamide adhesive according to claim 2, wherein The molar ratio of the long carbon chain unsaturated fatty dicarboxylic acid to the polyamine is 1:0.5-2.

10. The method for preparing the vegetable oil-based polyamide adhesive according to claim 2, characterized in that The temperature of the melt polycondensation reaction is 160-260° C., and the time of the melt polycondensation reaction is 4-6 hours.

Images