Water-based vacuum plastic suction adhesive and preparation method thereof
By adjusting the particle size and solid content of the waterborne polyurethane emulsion in the waterborne vacuum forming adhesive, the penetration problem on low-density fiberboard was solved, achieving a good bonding effect and meeting the application requirements in furniture manufacturing.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-12
- Publication Date
- 2026-03-13
AI Technical Summary
Existing water-based vacuum forming adhesives tend to penetrate low-density fiberboard, resulting in insufficient bonding strength and affecting the bonding effect. This is especially true for fiberboard with a density ≤0.68g/cm3, where the chip removal rate is difficult to meet industry application requirements.
By using an aqueous polyurethane emulsion with an average particle size of over 200 nm and a solid content of over 59%, and by adjusting the molecular weight and crosslinking density of the polyurethane emulsion, an aqueous vacuum forming adhesive was prepared, ensuring that it does not penetrate onto low-density fiberboard and provides good bonding effect.
It achieves anti-permeability on fiberboard with a density ≤0.68g/cm3, with a chip removal rate of over 90%, ensuring excellent adhesion between the PVC film and the board, and meeting the application requirements in the industry.
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Figure CN121652686A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of vacuum forming technology, and more specifically, to a water-based vacuum forming adhesive and its preparation method. Background Technology
[0002] Vacuum forming is a process that uses atmospheric pressure to tightly bond PVC film to materials such as fiberboard that have been treated with adhesive (vacuum forming glue). This process is not only simple to operate but also inexpensive to produce, making it widely used in furniture manufacturing, especially in the production of cabinets, paint-free doors, and sliding doors. Vacuum forming glues are divided into oil-based and water-based glues. With increasing consumer emphasis on environmental protection and health, most furniture factories now choose to use water-based vacuum forming glues. As market competition intensifies, furniture factories, driven by the need to reduce costs, are opting for lower-density fiberboard (lower-density fiberboard refers to fiberboard with a density ≤ 0.68 g / cm³). 3 Furniture is made from low-density fiberboard (HDF). However, existing water-based vacuum forming adhesives tend to penetrate HDF easily, resulting in insufficient adhesive on the board surface, affecting bonding strength and easily causing quality problems. In the performance evaluation system of vacuum forming adhesives, the chip residue rate is an important technical indicator for measuring its bonding performance with the substrate. The higher the chip residue rate, the better the bonding performance with the substrate. When the chip residue rate reaches 50% or more, the industry considers it to basically meet the requirements of practical applications, and when the chip residue rate reaches 80% or more, it is considered to have excellent bonding performance.
[0003] Therefore, it is particularly important to study a water-based vacuum forming adhesive that can achieve impermeability and good bonding effect on low-density fiberboard. Summary of the Invention
[0004] The purpose of this invention is to overcome the defects or shortcomings of existing water-based vacuum forming adhesives and to provide a water-based vacuum forming adhesive. This water-based vacuum forming adhesive has good anti-permeability effect when applied to low-density fiberboard, and also features strong adhesion and good chip removal effect.
[0005] Another object of the present invention is to provide a method for preparing the above-mentioned water-based vacuum forming adhesive.
[0006] To achieve the above objectives, the present invention provides the following technical solution: A water-based vacuum forming adhesive, comprising the following components in parts by weight: 40-60 parts of waterborne polyurethane emulsion; 40-60 parts of ethylene-vinyl acetate emulsion; Neutralizing agent 0.1~1 part; Leveling agent 0.1~1 part; Defoamer 0.05~1 part; Preservative 0.1 to 1 part; Thickener 0.1~1 part; The average particle size of the aqueous polyurethane emulsion is above 200 nm. The solid content of the waterborne polyurethane emulsion is above 59%.
[0007] The inventors discovered that using waterborne polyurethane with an average particle size of over 200nm and a solid content of over 59% as a raw material in waterborne vacuum forming adhesive can solve the penetration problem of existing waterborne vacuum forming adhesives on low-density fiberboards, and has a good film-forming effect on the board surface, providing a good bonding effect.
[0008] Preferably, the average particle size of the aqueous polyurethane emulsion is 200~350nm.
[0009] More preferably, the average particle size of the aqueous polyurethane emulsion is 200~300nm.
[0010] When the average particle size of waterborne polyurethane emulsion is greater than 300 nm, it is more prone to sedimentation, resulting in a shorter shelf life.
[0011] Most preferably, the average particle size of the aqueous polyurethane emulsion is 240~300nm.
[0012] Preferably, the reaction raw materials of the waterborne polyurethane include diisocyanate, polyester diol, hydrophilic monomer and amine chain extender.
[0013] Preferably, the molar ratio of NCO groups in the diisocyanate to OH groups in the polyester diol is 1.4~1.6:1.
[0014] Preferably, the purity of the diisocyanate is 99% or higher.
[0015] Preferably, the diisocyanate is one or more of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, isophorone diisocyanate, 1,4-diisocyanate-cyclohexane, toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, phenylenediamine diisocyanate, naphthalene-1,5-diisocyanate, or tetramethylphenylenediamine diisocyanate.
[0016] More preferably, the diisocyanate is one or more of hexamethylene diisocyanate, isophorone diisocyanate, or toluene diisocyanate.
[0017] Preferably, the number average molecular weight of the polyester diol is 500 to 5000.
[0018] More preferably, the number average molecular weight of the polyester diol is 1000-3000.
[0019] Preferably, the polyester diol is one or more of poly(1,4-butanediol adipate), poly(1,6-hexanediol adipate), poly(hexanediol adipate), or poly(neopentylenediol adipate).
[0020] The hydrophilic monomer can be a commonly used hydrophilic monomer for synthesizing polyurethane. Preferably, the hydrophilic monomer is a sulfonate-type hydrophilic monomer; the sulfonate-type hydrophilic monomer contains two or more groups that are reactive with NCO groups.
[0021] More preferably, the hydrophilic monomer is a sulfonate-type hydrophilic monomer containing two groups reactive with the NCO group. Examples include sodium ethylenediaminoethanesulfonate, sodium 1,2-dihydroxy-3-propanesulfonate, or sodium diaminoethanesulfonate AAS-Na. The structural formula of sodium diaminoethanesulfonate AAS-Na is:
[0022] Wherein, R is one of an aromatic hydrocarbon, an alkane, or an alicyclic hydrocarbon. In this invention, there is no special limitation on the number of carbon atoms in the aromatic hydrocarbon, alkane, or alicyclic hydrocarbon of R; generally, commercially available products can meet this requirement.
[0023] Common examples include sodium ethylenediaminoethanesulfonate. The hydrophilic monomer can be a commercially available product, such as Evonik's Vestamin A95, Wanhua Chemical's ANS-50, or Guangzhou Xingusheng Chemical Technology Co., Ltd.'s Sagazone 095.
[0024] Preferably, the hydrophilic monomer is Sagazone 095 from Guangzhou Xingusheng Chemical Technology Co., Ltd.
[0025] Preferably, the amine chain extender is one or more of ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, isophoronediamine, or diethylenetriamine.
[0026] More preferably, the amine chain extender is ethylenediamine.
[0027] Preferably, the aqueous polyurethane emulsion is prepared by the following steps: S1. Stir and heat the diisocyanate and polyester diol to react. After the reaction is complete, the prepolymer is obtained. S2. Dissolve the prepolymer in a solvent, add hydrophilic monomers and amine chain extenders to react, and after the reaction is complete, polyurethane is obtained; S3. Disperse polyurethane in water and distill under reduced pressure to obtain the aqueous polyurethane emulsion.
[0028] In the preparation of waterborne polyurethane, when the hydrophilic monomer and other synthesis conditions are fixed, the amount of chain extender added plays a dominant role in the molecular weight and crosslinking structure of the system. This application uses a fixed amount of hydrophilic monomer and polyester diol, and adjusts the amounts of diisocyanate and chain extender to change the molecular weight and crosslinking density of the polyurethane, thereby affecting its dispersion behavior during emulsification and ultimately achieving effective control over the average particle size of the emulsion.
[0029] As is known to those skilled in the art, in the preparation of polyurethane, the main reactants (especially polyols) must undergo strict dehydration treatment to avoid side reactions between water and isocyanate groups, which could lead to uncontrolled crosslinking and gelation of the reaction system. A dehydration method may be to stir the reactants at 110-130°C and then dehydrate them under vacuum for 1-2 hours.
[0030] Those skilled in the art will know that catalysts can be added to increase the reaction rate during the preparation of polyurethane, such as one or more of dibutyltin dilaurate, stannous octoate, tetramethylbutanediamine, or triethylenediamine. Preferably, the catalyst is dibutyltin dilaurate.
[0031] As is known to those skilled in the art, in the preparation of polyurethane, the amount of catalyst added is generally 0.01 to 1% of the total mass of the reaction system.
[0032] Those skilled in the art will know that the content of NCO groups in the reaction system can be determined by titration to determine the degree of reaction. Preferably, the condition for determining the completeness of the reaction in step S1 or S2 is that the reaction solution is titrated with -NCO value, and the deviation of the titration result from the theoretical value is ≤5%, then the reaction is determined to be complete.
[0033] Preferably, the reaction temperature in step S1 is 80~90℃.
[0034] Preferably, the solvent in step S2 is one or more of acetone, N,N-dimethylformamide, N,N-dimethylacetamide, or dimethyl sulfoxide.
[0035] Preferably, the reaction temperature in step S2 is 30~50℃.
[0036] As is known to those skilled in the art, shear rate is a key parameter for controlling the average particle size and distribution of waterborne polyurethane emulsions during polyurethane dispersion in water. If the shear rate is too high, the provided shear force is excessive, causing the emulsion droplets to break up, resulting in an emulsion with a smaller average particle size and narrower distribution. Therefore, it is necessary to control the shear dispersion rate during polyurethane dispersion. Preferably, the dispersion rate in step S3 is 600~800 r / min. Preferably, the dispersion time in step S3 is 0.5~1 h.
[0037] As is known to those skilled in the art, ethylene-vinyl acetate emulsion is the most commonly used base resin in water-based vacuum forming adhesives, which can increase the adhesion of PVC films. In the vacuum forming process, the ethylene-vinyl acetate emulsion needs to soften and melt rapidly at the vacuum forming temperature; therefore, products with a glass transition temperature (Tg) of -10 to 10°C are typically selected, such as, but not limited to, one or more of DA102 from Dalian Chemical or EP708 from Wacker Chemie.
[0038] In this invention, commonly used neutralizing agents in the prior art can be selected, such as, but not limited to, one or more of triethanolamine, triethylamine, or 2-amino-2-methyl-1-propanol. Preferably, the neutralizing agent is 2-amino-2-methyl-1-propanol.
[0039] In this invention, commonly used leveling agents in the prior art can be selected, such as, but not limited to, one or more of BYK333, BYK346, and BYK348 from BYK Chemical. Preferably, the leveling agent is BYK346 from BYK Chemical.
[0040] In this invention, commonly used defoamers in the prior art can be selected, such as, but not limited to, one or more of BYK011, BYK014, BYK019, BYK022, BYK024, BYK025, BYK028, BYK-1786, or BYK-094 from BYK Chemical. Preferably, the defoamer is BYK028 from BYK Chemical.
[0041] In this invention, commonly used preservatives in the prior art can be selected. The preservative should be able to broadly kill bacteria, fungi, yeasts, and algae, among other microorganisms. Examples include, but are not limited to, one or more of 2-methyl-4-isothiazolin-3-one, 2-methyl-5-chloro-4-isothiazolin-3-one, 1,2-benzisothiazolin-3-one, 2,2-dibromo-3-hypopropamide, bis(hydroxymethyl)imidazolidinyl urea, phenyl p-hydroxybenzoate, potassium dihydroxymethyldimethylhydantoin sorbate, or polyhexamethylene biguanide hydrochloride. Preferably, the preservative is a mixture of 2-methyl-4-isothiazolin-3-one and 2-methyl-5-chloro-4-isothiazolin-3-one, such as Dow Chemical's KATHON LXE.
[0042] In this invention, commonly used thickeners in the prior art can be selected, such as, but not limited to, one or more of polyurethane associative thickeners, acrylate alkali-swellable thickeners, or cellulose. Preferably, the thickener is a polyurethane associative thickener, such as Borchi® Gel 0620 or Borchi® Gel 0625 from Borchis.
[0043] The preparation method of the above-mentioned water-based vacuum forming adhesive is also within the scope of protection of this invention, including the following steps: first, water-based polyurethane emulsion, ethylene-vinyl acetate emulsion and neutralizing agent are stirred and mixed evenly, and then leveling agent, defoamer, preservative and thickener are added in sequence and stirred and mixed evenly to obtain the water-based vacuum forming adhesive.
[0044] As is known to those skilled in the art, vacuum forming adhesive is a specialized adhesive used to bond fiberboard to PVC film. Due to differences in manufacturing processes, fiberboard typically has different density specifications. Fiberboards of different densities exhibit significant differences in properties such as surface porosity and mechanical strength, which directly affects the penetration of the vacuum forming adhesive onto their surface. Preferably, the density of the fiberboard is 0.3~0.68 g / cm³. 3 More preferably, the density of the fiberboard is 0.5~0.65 g / cm³. 3 .
[0045] Compared with the prior art, the beneficial effects of the present invention include: This invention provides a water-based vacuum forming adhesive. By adjusting the average particle size and solid content of the water-based polyurethane emulsion in the water-based vacuum forming adhesive, this invention improves the anti-permeability effect of the adhesive, making it less likely for the adhesive to penetrate into the pores of fiberboards of various densities, especially those with a density ≤0.68 g / cm³. 3 This allows the PVC film to form a good film on fiberboard of various densities, providing a good bond between the PVC film and the board, thus solving the penetration problem of existing water-based vacuum forming adhesives on lower density fiberboards. Attached Figure Description
[0046] Figure 1 This is a diagram showing the bonding effect of the water-based vacuum forming adhesive prepared in Example 1 of the present invention.
[0047] Figure 2 This is a diagram showing the bonding effect of the water-based vacuum forming adhesive prepared in Comparative Example 1 of the present invention. Detailed Implementation
[0048] The present invention will be further described below with reference to embodiments and comparative examples. These embodiments are merely typical descriptions of the present invention, but the present invention is not limited thereto. Unless otherwise specified, the test methods used in the following embodiments and comparative examples are conventional methods, and the raw materials and reagents used are commercially available from conventional commercial sources.
[0049] The raw materials used in each embodiment and comparative example are shown in Table 1:
[0050] Example 1 This embodiment provides a water-based vacuum forming adhesive, the preparation method of which includes the following steps: 100g of water-based polyurethane emulsion and 100g of ethylene-vinyl acetate emulsion 1 are added to a container equipped with an electric stirrer. 1g of neutralizing agent is added at a stirring speed of 200r / min and stirred for 20min. Then, 0.1g of defoamer, 0.2g of preservative, 0.2g of leveling agent, and 0.2g of thickener are added sequentially and stirred at high speed for 2h until uniform, thus obtaining the water-based vacuum forming adhesive.
[0051] The preparation method of the above-mentioned waterborne polyurethane emulsion includes the following steps: S1. In a glass reactor equipped with an electric stirrer, a reflux condenser, and a thermocouple thermometer, add 100g of PBA2000 and dehydrate under vacuum at 120℃ for 2h. Then add 13g of hexamethylene diisocyanate and 0.008g of dibutyltin dilaurate catalyst and react at 85℃ for 2h to obtain the prepolymer. S2. Add 140g of acetone to dilute the prepolymer. When the temperature drops to 40℃, add 6g of sodium ethylenediamine ethanesulfonate (Sagazone 095) and 0.85g of ethylenediamine and react for 45min to obtain polyurethane. S3. Under a shear force of 600 r / min, the polyurethane is dispersed in 80 g of deionized water and dispersed for 30 min. Then, acetone is removed under reduced pressure at 60 °C. 0.2 g of defoamer and 0.1 g of preservative are added and stirred for 10 min to obtain the waterborne polyurethane emulsion.
[0052] The solid content and average particle size of the waterborne polyurethane emulsion prepared in this embodiment are shown in Table 5.
[0053] Examples 2-9 Examples 2-9 provide different water-based vacuum forming adhesives, differing from Example 1 only in the water-based polyurethane emulsion used. Specific formulations are shown in Table 2. The water-based polyurethane emulsions prepared according to the formulations in Table 2 using the preparation method of Example 1 are shown in Table 5. The solid content and average particle size of the water-based polyurethane emulsions prepared in each example are shown in Table 5.
[0054] Table 2 Formulations for the preparation of aqueous polyurethane emulsions in Examples 1-10 (Unit: g)
[0055] In the table, the R value refers to the molar ratio of NCO groups in the diisocyanate to OH groups in the polyester diol.
[0056] Examples 11-14 Examples 11-14 provide different water-based vacuum forming adhesives, differing from Example 1 only in the preparation formula of the water-based vacuum forming adhesive, as shown in Table 3. Examples 11-14 all use the water-based polyurethane emulsion prepared in Example 1 as their corresponding water-based polyurethane emulsion.
[0057] Table 3. Formulation of water-based vacuum forming adhesive for Examples 1 and 11-14 (unit: g)
[0058] Comparative Example 1 This comparative example provides an aqueous vacuum forming adhesive, which differs from Example 1 only in the use of a different aqueous polyurethane emulsion. The specific formulation is shown in Table 4. The aqueous polyurethane emulsion prepared according to the formulation in Table 4 using the preparation method of the aqueous polyurethane emulsion in Example 1 is shown in Table 5.
[0059] Comparative Example 2 This comparative example provides an aqueous vacuum forming adhesive, which differs from Example 1 only in the use of a different aqueous polyurethane emulsion. The specific formulation is shown in Table 4. The aqueous polyurethane emulsion prepared according to the formulation in Table 4 using the preparation method of the aqueous polyurethane emulsion in Example 1 is shown in Table 5.
[0060] Comparative Example 3 This comparative example provides an aqueous vacuum forming adhesive, which differs from Example 1 only in the use of a different aqueous polyurethane emulsion. The specific formulation is shown in Table 4. The aqueous polyurethane emulsion prepared according to the formulation in Table 4 using the preparation method of the aqueous polyurethane emulsion in Example 1 is shown in Table 5.
[0061] Table 4. Formulations for the preparation of aqueous polyurethane emulsions in Comparative Examples 1-3 (Unit: g)
[0062] In the table, the R value refers to the molar ratio of NCO groups in the diisocyanate to OH groups in the polyester diol.
[0063] Performance testing and characterization (1) Characterization of waterborne polyurethane emulsion The average particle size and solid content of the aqueous polyurethane emulsions (PUDs) prepared in Examples 1-10 and Comparative Examples 1-3 were determined, and the results are shown in Table 5 below. The specific test methods are as follows: 1. Determination of solid content: Clean the watch glass and weigh it using an electronic balance; this mass is M1. Place 1-2g of waterborne polyurethane emulsion into the watch glass and weigh it; this mass is M2. Place the watch glass containing the waterborne polyurethane emulsion in a 130℃ oven and bake for 2 hours; weigh the dried watch glass, M3. Calculate the solid content using the following formula:
[0064] 2. Determination of average particle size: The average particle size was determined using a Zetaplus / 90plus Zeta potential and laser particle size analyzer (Brookhaven, USA).
[0065] Table 5. Solid content and average particle size test results of the waterborne polyurethane emulsions prepared in Examples 1-10 and Comparative Examples 1-3.
[0066] (2) Performance testing of water-based vacuum forming adhesive Application Test 1 The adhesive properties of the water-based vacuum forming adhesives prepared in Examples 1-14 and Comparative Examples 1-3 were tested, and the results are shown in Table 6 below. Figure 1 and Figure 2 As shown. The specific test method is as follows: 1. Evaluation of bonding effect: First, at a density of 0.65 g / cm³... 3 The prepared water-based vacuum forming adhesive was sprayed onto the fiberboard and allowed to dry at room temperature for 1 hour. The adhesive-coated board was then placed in a vacuum forming machine (negative pressure machine) for vacuum forming (forming conditions: PVC film thickness 25 mils, forming temperature 180℃, forming time 180s). Finally, the vacuum-formed sample was cooled to room temperature, and the PVC film was peeled off the fiberboard. The material damage effect was observed, with the chipping rate used as the evaluation index. The chipping rate was calculated using the following formula:
[0067] Table 6. Water-based vacuum forming adhesive at a density of 0.65 g / cm³ 3 Bonding performance test results on fiberboard
[0068] Table 6 shows that when the PVC film density is 0.65 g / cm³... 3When peeled from fiberboard, the chipping rate exceeds 90%, indicating that the water-based vacuum forming adhesive provided by this invention has excellent bonding performance. Simultaneously, the high chipping rate also indicates excellent anti-permeability properties. During the adhesive drying process, the water-based vacuum forming adhesive cannot penetrate into the pores of the fiberboard, thus ensuring sufficient adhesive remains on the fiberboard surface, thereby forming a continuous adhesive layer with excellent bonding performance. Conversely, when the average particle size or solid content of the water-based vacuum forming adhesive does not meet the requirements, it is prone to penetration into fiberboards of the same density, thus affecting its bonding performance, resulting in a chipping rate of only 30% at most, which cannot meet the application requirements in the industry. Figure 1 and Figure 2 The difference in the shaving rate of PVC film after using different water-based vacuum forming adhesives is clearly visible.
[0069] Application Test 2 The water-based vacuum forming adhesives prepared in Examples 1, 3, 9 and Comparative Examples 1-3 have a density of 0.5 g / cm³. 3 The bonding performance was tested on the board material, and the results are shown in Table 7 below.
[0070] Table 7. Water-based vacuum forming adhesive at a density of 0.5 g / cm³ 3 Bonding performance test results on fiberboard
[0071] As shown in Table 7, when the PVC film density is 0.5 g / cm³... 3 When peeled from fiberboard, the chipping rate exceeds 80%, indicating that the water-based vacuum forming adhesive provided by this invention has excellent bonding performance. Simultaneously, the high chipping rate also indicates excellent anti-permeability properties. During the adhesive drying process, the water-based vacuum forming adhesive cannot penetrate into the pores of the fiberboard, thus ensuring sufficient adhesive remains on the fiberboard surface, thereby forming a continuous adhesive layer with excellent bonding performance. Conversely, when the average particle size or solid content of the water-based vacuum forming adhesive does not meet the requirements, it is prone to penetration into fiberboards of the same density, thus affecting its bonding performance, resulting in a chipping rate of only 15% at most, which cannot meet the application requirements in the industry.
[0072] Application Test 3 The water-based vacuum forming adhesives prepared in Examples 1, 3, 9 and Comparative Examples 1-3 have a density of 0.3 g / cm³. 3 The bonding performance was tested on the board material, and the results are shown in Table 8 below.
[0073] Table 8. Water-based vacuum forming adhesive at a density of 0.3 g / cm³ 3 Bonding performance test results on fiberboard
[0074] As can be seen from the data in Table 8, even in fiberboard with a density of only 0.3 g / cm³, the phenomenon of water-based vacuum forming adhesive provided by the present invention penetrating into the pores of the fiberboard is greatly alleviated, so that a sufficiently strong adhesive layer can still be formed on the surface of the fiberboard, thereby achieving a chip removal rate of 50%, which basically meets the application requirements in the industry.
[0075] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.
Claims
1. A water-based vacuum forming adhesive, characterized in that, The water-based vacuum forming adhesive comprises the following components in parts by weight: 40-60 parts of waterborne polyurethane emulsion; 40-60 parts of ethylene-vinyl acetate emulsion; Neutralizing agent 0.1~1 part; Leveling agent 0.1~1 part; Defoamer 0.05~1 part; Preservative 0.1 to 1 part; Thickener 0.1~1 part; The average particle size of the aqueous polyurethane emulsion is above 200 nm. The solid content of the waterborne polyurethane emulsion is above 59%.
2. The water-based vacuum forming adhesive according to claim 1, characterized in that, The reaction raw materials for the waterborne polyurethane emulsion include diisocyanate, polyester diol, hydrophilic monomer and amine chain extender.
3. The water-based vacuum forming adhesive according to claim 2, characterized in that, The molar ratio of NCO groups in the diisocyanate to OH groups in the polyester diol is 1.4~1.6:
1.
4. The water-based vacuum forming adhesive according to claim 2, characterized in that, The number-average molecular weight of the polyester diol is 500-5000.
5. The water-based vacuum forming adhesive according to claim 2, characterized in that, The polyester diol is one or more of poly(1,4-butanediol adipate), poly(1,6-hexanediol adipate), poly(hexanediol adipate), or poly(neopentyl adipate-1,6-hexanediol adipate).
6. The water-based vacuum forming adhesive according to claim 2, characterized in that, The diisocyanate is one or more of the following: tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, isophorone diisocyanate, 1,4-diisocyanate-cyclohexane, toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, phenylenediamine diisocyanate, naphthalene-1,5-diisocyanate, or tetramethylphenylenediamine diisocyanate.
7. The water-based vacuum forming adhesive according to claim 2, characterized in that, The hydrophilic monomer is a sulfonate-type hydrophilic monomer; the sulfonate-type hydrophilic monomer contains two or more groups that are reactive with NCO groups.
8. The water-based vacuum forming adhesive according to claim 2, characterized in that, The amine chain extender is one or more of ethylenediamine, propylenediamine, butanediamine, hexamethylenediamine, isophorone diamine, or diethylenetriamine.
9. The water-based vacuum forming adhesive according to claim 1, characterized in that, The glass transition temperature of the ethylene-vinyl acetate emulsion is -10 to 10°C.
10. A method for preparing the water-based vacuum forming adhesive according to any one of claims 1 to 9, characterized in that, Includes the following steps: First, the water-based polyurethane emulsion, ethylene-vinyl acetate emulsion, and neutralizer are stirred and mixed evenly. Then, the leveling agent, defoamer, preservative, and thickener are added in sequence and stirred and mixed evenly to obtain the water-based vacuum forming adhesive.