Anti-yellowing TPU (thermoplastic polyurethane) pressure-sensitive adhesive for car clothing and preparation method of anti-yellowing TPU pressure-sensitive adhesive

Abstract

The invention discloses a yellowing-resistant TPU (thermoplastic polyurethane) pressure-sensitive adhesive for car clothing, which is prepared from the following raw materials in parts by weight: 75 to 80 parts of soft monomer, 65 to 75 parts of hard monomer, 10 to 11 parts of functional monomer, 230 to 250 parts of solvent, 0.1 to 0.5 part of initiator, 1 to 5 parts of curing agent, 10 to 15 parts of polymerization inhibitor and photocatalyst. The self-made photocatalyst is adopted, oxygen inside and outside the colloid is converted into singlet < 1 > O2, < 1 > O2 oxidized DMSO, DMF and other solvents under illumination, so that oxygen is consumed, the yellowing resistance time of the colloid is prolonged, and the adhesive has excellent persistent adhesion in a high-temperature environment, has the characteristics of yellowing resistance, high stripping, low climbing, small viscosity and strong persistent adhesion, and can be widely applied to the field of high-temperature environment. Not only is the operation difficulty of using the pressure-sensitive adhesive in the production process of the automobile cover film reduced, but also the quality of the automobile cover film produced by using the pressure-sensitive adhesive is ensured.

Description

Technical Field

[0001] The present invention relates to the field of adhesives, and particularly to a yellowing-resistant pressure-sensitive adhesive for TPU car wraps and a preparation method thereof. Background Art

[0002] TPU car wraps are materials widely used in automotive paint protection films, which have the characteristics of stable structure, water resistance, softness, self-healing, and high extensibility. Pressure-sensitive adhesives are an essential component structure in TPU car wraps. Currently, automotive car wraps are prone to yellowing and aging problems after long-term use. The main reason is that the pressure-sensitive adhesives on the car wraps are prone to yellowing and aging. Currently, car wrap films generally reduce yellowing by adding chemical additives such as ultraviolet absorbers and antioxidants, but the yellowing resistance is not persistent and the effect is not significant. Therefore, it is crucial to develop a pressure-sensitive adhesive that is resistant to yellowing and aging and does not affect the adhesive bonding, cohesion, and durability of the TPU car wrap colloid.

[0003] Chinese invention patent CN112708369A discloses a self-healing yellowing-resistant invisible car wrap protection film and its manufacturing process. Adding ultraviolet absorbers and antioxidants to the self-healing layer and the pressure-sensitive adhesive layer can increase the yellowing resistance and weather resistance of the invisible car wrap film. However, ultraviolet absorbers and antioxidants are unstable in the colloid and there is a risk of precipitation during long-term use, resulting in a decrease in the yellowing resistance effect. Chinese invention patent CN116120844A discloses a wear-resistant and yellowing-resistant car wrap film and its preparation method. Its glue layer is adhered to the automotive paint surface, and the wear-resistant and yellowing-resistant layer is exposed outside, which can reduce the scratching and yellowing of the automotive paint surface, but it cannot improve the aging and yellowing effect of the pressure-sensitive adhesive. Summary of the Invention

[0004] In order to develop a pressure-sensitive adhesive that is resistant to yellowing and aging and does not affect the adhesive bonding, cohesion, and durability of the TPU car wrap colloid, the first aspect of the present invention provides a yellowing-resistant pressure-sensitive adhesive for TPU car wraps. The preparation raw materials include at least: 75 - 80 parts by weight of soft monomers, 65 - 75 parts by weight of hard monomers, 10 - 11 parts by weight of functional monomers, 230 - 250 parts by weight of solvents, 0.1 - 0.5 parts by weight of initiators, 1 - 5 parts by weight of curing agents, and 10 - 15 parts by weight of inhibitors. The preparation raw materials also include a photocatalyst.

[0005] As an embodiment, the photocatalyst is selected from at least one of arylamine-based photocatalysts, nano-metal composite catalysts, or MOF-based catalysts.

[0006] As an embodiment, the usage amount of the photocatalyst is 0.4 - 0.9 parts by weight.

[0007] During the experiment, the inventor found that the TPU car wrap glue was prone to yellowing during long-term use, which affected the actual use of the invisible car wrap film. The inventor added a photocatalyst prepared by the inventor to the TPU car wrap glue, which could improve the yellowing resistance of the TPU car wrap glue and enhance the anti-aging effect. It was speculated that the possible reason was that the prepared photocatalyst could consume the oxygen inside and outside the TPU car wrap glue during use, avoiding the oxidation of monomers in the TPU car wrap glue, thereby reducing the yellowing effect in the TPU car wrap glue.

[0008] As an implementation method, the preparation raw materials of the arylamine photocatalyst at least include: 10 - 30 mL of glacial acetic acid, 500 - 550 mg of diphenylamine, 2 - 3 mg of cesium carbonate, 10 - 30 mL of toluene, and 90 - 100 mg of palladium catalyst. The preparation raw materials also include dibromobenzoyl and aminobenzene.

[0009] In the present invention, mg and mL are used to clarify the addition amounts, and weight units such as μg, g, kg, t, etc. can be selected, and volume units such as μL, L, etc. can be selected.

[0010] As an implementation method, the dibromobenzoyl is selected from at least one of 4,4 - dibromobenzoyl, 2,4 - dibromobenzoyl, 2,5 - dibromobenzoyl, or 2,6 - dibromobenzoyl.

[0011] As an implementation method, the aminobenzene is selected from at least one of 1,2 - phenylenediamine or 2,2 - diaminobiphenyl.

[0012] As an implementation method, the usage amount of the dibromobenzoyl is 1072 - 1872 mg, and the usage amount of the aminobenzene is 332 - 532 mg.

[0013] As an implementation method, the palladium catalyst is Pd2(dba)3.

[0014] The photocatalyst introduced in the present invention is an arylamination catalyst formed by the reaction of quinoxaline intermediate and diphenylamine under the catalysis of Pd2(dba)3. During the curing process, the TPU car wrap colloid formed has a large peel strength and strong cohesion. The introduced photocatalyst converts the oxygen inside and outside the colloid into singlet 1 O2 1 O2 oxidizes solvents such as DMSO and DMF, so that the oxygen is consumed, prolonging the yellowing resistance time of the colloid. At the same time, the monomers are added dropwise to the solvent through the reverse dropwise process for sufficient cross-linking reaction, improving the firmness and durability of the adhesion, thereby avoiding the yellowing and aging of the TPU car wrap glue.

[0015] As an implementation method, the preparation method of the photocatalyst includes the following steps:

[0016] S1 Mix dibromobenzoyl, aminobenzene and glacial acetic acid, reflux at 120 °C for 2 - 5 h under an inert gas atmosphere, cool to room temperature, distill under reduced pressure to obtain a crude product, purify by chromatography, and dry under vacuum to obtain an intermediate product;

[0017] S2 Mix the intermediate product, diphenylamine, cesium carbonate, toluene, and a palladium catalyst, reflux for 10 - 20 h under an inert gas atmosphere, cool to room temperature, distill under reduced pressure, purify by chromatography, and dry under vacuum to obtain a photocatalyst.

[0018] As an embodiment, the inert gas is argon.

[0019] As an embodiment, the vacuum drying temperature in step S1 is 30 - 50 °C, and the drying time is 3 - 8 h.

[0020] As an embodiment, the vacuum drying temperature in step S2 is 30 - 50 °C, and the drying time is 10 - 15 h.

[0021] As an embodiment, the solvent includes solvent I, solvent II, solvent III, and solvent IV, and the solvent I, solvent II, solvent III, and solvent IV are each selected from at least one of ethyl acetate, toluene, N,N - dimethylformamide, dimethyl sulfoxide, acetone, or isopropanol.

[0022] As an embodiment, the weight ratio of solvent I, solvent II, solvent III, and solvent IV is (75 - 85):(80 - 85):(35 - 40):(30 - 40).

[0023] As an embodiment, the weight ratio of solvent I, solvent II, solvent III, and solvent IV is 79.5:82:37:34.1.

[0024] As an embodiment, solvent I is a combination of ethyl acetate and acetone, and the weight ratio is (70 - 75):(5 - 10); as an embodiment, the weight ratio of ethyl acetate and acetone is 72:7.5.

[0025] As an embodiment, solvent II is a combination of ethyl acetate, toluene, and N,N - dimethylformamide, and the weight ratio is (50 - 60):(5 - 10):(15 - 20); as an embodiment, the weight ratio of ethyl acetate, toluene, and N,N - dimethylformamide is 55:8:19.

[0026] As an embodiment, solvent III is ethyl acetate or toluene.

[0027] As an implementation manner, the solvent IV is a combination of toluene and isopropanol, and the weight ratio is (20 - 25):(5 - 10); as an implementation manner, the weight ratio of toluene to isopropanol is 24.5:9.6.

[0028] As an implementation manner, the soft monomer includes at least one of 2-ethylhexyl acrylate, ethyl acrylate, butyl acrylate, or isooctyl acrylate.

[0029] As an implementation manner, the hard monomer includes at least one of methyl acrylate, methyl methacrylate, or vinyl acetate.

[0030] As an implementation manner, the functional monomer includes at least one of acrylic acid, β-carboxyethyl acrylate, or methacrylic acid.

[0031] As an implementation manner, the initiator includes, but is not limited to, azobisisobutyronitrile.

[0032] As an implementation manner, the curing agent is acetylacetone, and the inhibitor is aluminum acetylacetonate.

[0033] The second aspect of the present invention provides a method for preparing a yellowing-resistant TPU car film pressure-sensitive adhesive, including the following steps:

[0034] M1: After mixing the solvent I evenly, heat it under reflux and maintain at 85 - 90 °C to obtain component A;

[0035] M2: Mix the photocatalyst, soft monomer, hard monomer, functional monomer, solvent II, and 60 - 70 wt% of the initiator evenly to obtain component B; mix the solvent III and the remaining initiator evenly to obtain component C; mix the solvent IV, curing agent, and inhibitor evenly to obtain component D;

[0036] M3: Dropwise add component B into component A, and the dropping time is 120 - 150 min. After dropping, keep warm for 50 - 70 min;

[0037] M4: After keeping warm, dropwise add component C, and the dropping time is 10 - 15 min. After dropping, keep warm for 150 - 200 min;

[0038] M5: After keeping warm, stop heating, cool down to below 40 °C, dropwise add component D, and the dropping time is 20 - 40 min. After dropping, stir for 30 - 40 min to obtain the yellowing-resistant TPU car film pressure-sensitive adhesive.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] (1) For the yellowing-resistant TPU car film pressure-sensitive adhesive of the present invention, a self-made photocatalyst is used to convert oxygen inside and outside the colloid into singlet oxygen under light.1 O2, 1 O2 oxidizes solvents such as DMSO and DMF, thereby consuming oxygen and prolonging the yellowing resistance time of the colloid.

[0041] (2) The photocatalyst in the yellowing-resistant TPU car wrap pressure-sensitive adhesive of the present invention synthesizes the intermediate quinoxaline from 4,4-dibromobenzil and 1,2-phenylenediamine. As an electron acceptor group and diphenylamine as an electron donor group, an organic small molecule photocatalyst is synthesized through a coupling reaction, which has excellent oxygen-consuming yellowing resistance effect.

[0042] (3) The yellowing-resistant TPU car wrap pressure-sensitive adhesive of the present invention has good viscosity, high peel strength in high-temperature environment, and has a long working time.

[0043] (4) The yellowing-resistant TPU car wrap pressure-sensitive adhesive of the present invention has good adhesion to the steel plate after being attached to the PET film, excellent adhesion in high-temperature environment, and has the characteristics of yellowing resistance, high peel and low creep, small viscosity and strong adhesion. It not only reduces the operation difficulty of using the pressure-sensitive adhesive in the production process of the car wrap film, but also ensures the quality of the car wrap film produced using this pressure-sensitive adhesive.

[0044] (5) The yellowing-resistant TPU car wrap pressure-sensitive adhesive of the present invention makes the TPU car wrap film not turn yellow within 3000h in the ultraviolet aging test machine, and the performance such as peel strength and cohesion is basically unchanged compared with the pressure-sensitive adhesive without introducing the photocatalyst, solving the problem of car wrap yellowing. Detailed implementation mode

[0045] Example 1

[0046] A yellowing-resistant TPU car wrap pressure-sensitive adhesive, the preparation raw materials include, by weight: 75 parts of soft monomer, 65 parts of hard monomer, 10 parts of functional monomer, 232.6 parts of solvent, 0.35 part of initiator, 3.5 parts of curing agent, 11.6 parts of inhibitor, and 0.5 part of photocatalyst.

[0047] The photocatalyst is self-made, and the preparation raw materials include: 20 mL of glacial acetic acid, 508 mg of diphenylamine (CAS: 122-39-4), 2.768 mg of cesium carbonate, 20 mL of toluene, 92 mg of palladium catalyst, 1472 mg of dibromobenzil, and 432 mg of aminobenzene.

[0048] The dibromobenzil is 4,4-dibromobenzil; the aminobenzene is 1,2-phenylenediamine (CAS: 95-54-5).

[0049] The palladium catalyst is Pd2(dba)3.

[0050] The preparation method of the photocatalyst includes the following steps:

[0051] S1 Mix dibromobenzoyl, aminobenzene and glacial acetic acid, reflux at 120 °C for 3 h under an inert gas atmosphere, cool to room temperature, distill under reduced pressure to obtain a crude product, purify by chromatography, and dry under vacuum to obtain an intermediate product;

[0052] S2 Mix the intermediate product, diphenylamine, cesium carbonate, toluene, and a palladium catalyst, reflux for 15 h under an inert gas atmosphere, cool to room temperature, distill under reduced pressure, purify by chromatography, and dry under vacuum to obtain a photocatalyst.

[0053] The inert gas is argon.

[0054] In step S1, the vacuum drying temperature is 40 °C and the drying time is 5 h.

[0055] In step S2, the vacuum drying temperature is 40 °C and the drying time is 12 h.

[0056] The solvent includes solvent I, solvent II, solvent III, and solvent IV, with a weight ratio of 79.5:82:37:34.1.

[0057] Solvent I is a combination of ethyl acetate and acetone, with a weight ratio of 72:7.5.

[0058] Solvent II is a combination of ethyl acetate, toluene, and N,N-dimethylformamide, with a weight ratio of 55:8:19.

[0059] Solvent III is ethyl acetate.

[0060] Solvent IV is a combination of toluene and isopropanol, with a weight ratio of 24.5:9.6.

[0061] The soft monomer is isooctyl acrylate; the hard monomer is methyl acrylate; the functional monomer is acrylic acid.

[0062] The initiator is azobisisobutyronitrile.

[0063] The curing agent is acetylacetone, and the inhibitor is aluminum acetylacetonate.

[0064] A preparation method of a yellowing-resistant TPU vehicle wrap pressure-sensitive adhesive includes the following steps:

[0065] M1: After mixing solvent I evenly, heat under reflux and maintain at 85 - 90 °C to obtain component A;

[0066] M2: Mix the photocatalyst, soft monomer, hard monomer, functional monomer, solvent II, and 68.57 wt% of the initiator evenly to obtain component B; mix solvent III and the remaining initiator evenly to obtain component C; mix solvent IV, curing agent, and inhibitor evenly to obtain component D;

[0067] M3: Dropwise add Component B into Component A over a dropping time of 120 - 150 min, and keep the temperature for 60 min after the addition.

[0068] M4: After keeping the temperature, dropwise add Component C over a dropping time of 10 - 15 min, and keep the temperature for 180 min after the addition.

[0069] M5: After keeping the temperature, stop heating, cool down to below 40 °C, dropwise add Component D over a dropping time of 30 min, and stir for 30 - 40 min after the addition to obtain the yellowing - resistant TPU vehicle wrap pressure - sensitive adhesive.

[0070] Example 2

[0071] A yellowing - resistant TPU vehicle wrap pressure - sensitive adhesive and its preparation method. The specific implementation method is the same as that of Example 1, except that 4,4 - dibromobenzil in the preparation raw materials of the photocatalyst is replaced by 2,4 - dibromobenzil.

[0072] Example 3

[0073] A yellowing - resistant TPU vehicle wrap pressure - sensitive adhesive and its preparation method. The specific implementation method is the same as that of Example 1, except that 4,4 - dibromobenzil in the preparation raw materials of the photocatalyst is replaced by 2,5 - dibromobenzil.

[0074] Example 4

[0075] A yellowing - resistant TPU vehicle wrap pressure - sensitive adhesive and its preparation method. The specific implementation method is the same as that of Example 1, except that 4,4 - dibromobenzil in the preparation raw materials of the photocatalyst is replaced by 2,6 - dibromobenzil.

[0076] Example 5

[0077] A yellowing - resistant TPU vehicle wrap pressure - sensitive adhesive and its preparation method. The specific implementation method is the same as that of Example 1, except that 1,2 - phenylenediamine (CAS: 95 - 54 - 5) in the preparation raw materials of the photocatalyst is replaced by 2,2 - diaminobiphenyl (1454 - 80 - 4).

[0078] Example 6

[0079] A yellowing - resistant TPU vehicle wrap pressure - sensitive adhesive and its preparation method. The specific implementation method is the same as that of Example 1, except that the preparation raw materials of the photocatalyst include: 20 mL of glacial acetic acid, 508 mg of diphenylamine (CAS: 122 - 39 - 4), 2.768 mg of cesium carbonate, 20 mL of toluene, 92 mg of palladium catalyst, 1072 mg of dibromobenzil, and 432 mg of aminobenzene.

[0080] Example 7

[0081] A pressure-sensitive adhesive for a yellowing-resistant TPU vehicle wrap and its preparation method. The specific implementation method is the same as that of Example 1, except that the raw materials for preparing the photocatalyst include: 20 mL of glacial acetic acid, 508 mg of diphenylamine (CAS: 122-39-4), 2.768 mg of cesium carbonate, 20 mL of toluene, 92 mg of palladium catalyst, 1872 mg of dibromobenzoyl, and 432 mg of aminobenzene.

[0082] Example 8

[0083] A pressure-sensitive adhesive for a yellowing-resistant TPU vehicle wrap and its preparation method. The specific implementation method is the same as that of Example 1, except that the raw materials for preparing the photocatalyst include: 20 mL of glacial acetic acid, 508 mg of diphenylamine (CAS: 122-39-4), 2.768 mg of cesium carbonate, 20 mL of toluene, 92 mg of palladium catalyst, 1472 mg of dibromobenzoyl, and 332 mg of aminobenzene.

[0084] Example 9

[0085] A pressure-sensitive adhesive for a yellowing-resistant TPU vehicle wrap and its preparation method. The specific implementation method is the same as that of Example 1, except that the raw materials for preparing the photocatalyst include: 20 mL of glacial acetic acid, 508 mg of diphenylamine (CAS: 122-39-4), 2.768 mg of cesium carbonate, 20 mL of toluene, 92 mg of palladium catalyst, 1472 mg of dibromobenzoyl, and 532 mg of aminobenzene.

[0086] Example 10

[0087] A pressure-sensitive adhesive for a yellowing-resistant TPU vehicle wrap and its preparation method. The specific implementation method is the same as that of Example 1, except that the raw materials in parts by weight include: 75 parts of soft monomer, 65 parts of hard monomer, 10 parts of functional monomer, 232.6 parts of solvent, 0.35 part of initiator, 3.5 parts of curing agent, 11.6 parts of inhibitor, and 0.3 part of photocatalyst.

[0088] Example 11

[0089] A pressure-sensitive adhesive for a yellowing-resistant TPU vehicle wrap and its preparation method. The specific implementation method is the same as that of Example 1, except that the raw materials in parts by weight include: 75 parts of soft monomer, 65 parts of hard monomer, 10 parts of functional monomer, 232.6 parts of solvent, 0.35 part of initiator, 3.5 parts of curing agent, 11.6 parts of inhibitor, and 0.7 part of photocatalyst.

[0090] Example 12

[0091] A pressure-sensitive adhesive for yellowing-resistant TPU vehicle wrap and its preparation method. The specific implementation manner is the same as that of Example 1, except that the preparation raw materials include, by weight: 75 parts of soft monomer, 65 parts of hard monomer, 10 parts of functional monomer, 232.6 parts of solvent, 0.35 part of initiator, 3.5 parts of curing agent, 11.6 parts of inhibitor, and 0.9 part of photocatalyst.

[0092] Comparative Example 1

[0093] A pressure-sensitive adhesive for yellowing-resistant TPU vehicle wrap and its preparation method. The specific implementation manner is the same as that of Example 1, except that the preparation raw materials include, by weight: 75 parts of soft monomer, 65 parts of hard monomer, 10 parts of functional monomer, 232.6 parts of solvent, 0.35 part of initiator, 3.5 parts of curing agent, 11.6 parts of inhibitor, and 0 part of photocatalyst.

[0094] Comparative Example 2

[0095] A pressure-sensitive adhesive for yellowing-resistant TPU vehicle wrap. The specific implementation manner is the same as that of Example 1, except that

[0096] A preparation method of a pressure-sensitive adhesive for yellowing-resistant TPU vehicle wrap, comprising the following steps:

[0097] M1: After mixing the solvent I evenly, heat it under reflux and maintain at 85 - 90 °C to obtain Component A;

[0098] M2: Mix the photocatalyst, soft monomer, hard monomer, functional monomer, solvent II and 68.57 wt% of the initiator evenly to obtain Component B; Mix the solvent III and the remaining initiator evenly to obtain Component C; Mix the solvent IV, curing agent, and inhibitor evenly to obtain Component D;

[0099] M3: Drop Component A into Component B, and the dropping time is 120 - 150 min. After dropping, keep it warm for 60 min;

[0100] M4: After keeping warm, drop Component C, and the dropping time is 10 - 15 min. After dropping, keep it warm for 180 min;

[0101] M5: After keeping warm, stop heating, cool down to below 40 °C, drop Component D, and the dropping time is 30 min. After dropping, stir for 30 - 40 min to obtain the pressure-sensitive adhesive for yellowing-resistant TPU vehicle wrap.

[0102] Comparative Example 3

[0103] A pressure-sensitive adhesive for yellowing-resistant TPU vehicle wrap and its preparation method. The specific implementation manner is the same as that of Example 1, except that the photocatalyst is TiO2.

[0104] Comparative Example 4

[0105] A yellowing-resistant pressure-sensitive adhesive for TPU vehicle wrap and its preparation method. The specific implementation is the same as that of Example 1, except that the photocatalyst is g-C3N4.

[0106] Performance testing

[0107] 1. Preparation of TPU film: The structure of the TPU film from bottom to top is PET base film, self-healing coating, TPU base film. The pressure-sensitive adhesives prepared in the examples and comparative examples, and release film.

[0108] The preparation method of the TPU film includes the following steps:

[0109] a: Coating the pressure-sensitive adhesives prepared in the examples and comparative examples with a thickness of 25 - 28 μm on a 75 μm release film, and drying at 110 °C for 140 s;

[0110] b: Then coating 130 μm of TPU;

[0111] c: After drying, coating a 6 - 8 μm self-healing layer and drying at 110 °C for 90 s;

[0112] d: Aging at 50 °C for 72 h to obtain the TPU film.

[0113] Viscosity, ultraviolet aging experiment, and peel strength test are carried out.

[0114] Viscosity: Place the pressure-sensitive adhesives of the examples and comparative examples in a constant temperature water bath at 25 °C, and measure with a viscometer after the glue reaches 25 °C.

[0115] Ultraviolet aging experiment: Place it in an ultraviolet aging test machine for testing, and observe the time when yellowing occurs.

[0116] 180° peel strength: Refer to the PSTC-101 standard to test the 180° peel strength after 20 min, 24 h, 7 d, and 14 d.

[0117] Peel strength.

[0118] 2. Preparation of PET film: The structure of the PET film from bottom to top is PET base film, the pressure-sensitive adhesives prepared in the examples and comparative examples, and release film.

[0119] The preparation method of the PET film includes the following steps:

[0120] A: Coating the pressure-sensitive adhesives prepared in the examples and comparative examples with a thickness of 25 - 27 μm on a 50 μm PET base film, and drying at 120 °C for 180 s;

[0121] B: Aging at 65 °C for 24 h to obtain the PET film.

[0122] The PET film is attached to the steel plate and the holding tackiness test is carried out according to the PSTC-107 method at 120 °C for 48 h.

[0123] The test results are shown in Table 1.

[0124] Table 1

[0125]

[0126]

[0127]

[0128] The present invention introduces a self-synthesized organic photocatalyst. The monomer is added dropwise to the solvent through a reverse dropwise process to synthesize the car wrap glue. Compared with common photocatalysts and the process of adding traditional solvents to monomers, the synthesized acrylate car wrap glue has the characteristics of yellowing resistance, high peel strength and low creep, small viscosity and strong holding adhesion. It not only reduces the operation difficulty of using pressure-sensitive adhesive in the production process of car wrap films, but also ensures the quality of car wrap films produced using this pressure-sensitive adhesive.

Claims

1. A yellowing-resistant pressure-sensitive adhesive for TPU vehicle wraps, characterized in that, The preparation raw materials include, by weight parts, at least: 75 - 80 parts of soft monomer, 65 - 75 parts of hard monomer, 10 - 11 parts of functional monomer, 230 - 250 parts of solvent, 0.1 - 0.5 parts of initiator, 1 - 5 parts of curing agent, and 10 - 15 parts of inhibitor. The preparation raw materials also include a photocatalyst.

2. The pressure-sensitive adhesive for yellowing-resistant TPU vehicle wraps according to claim 1, wherein The photocatalyst is selected from at least one of arylamine photocatalysts, nano-metal composite catalysts, or MOF-based catalysts.

3. The pressure-sensitive adhesive for yellowing-resistant TPU vehicle wraps according to claim 1, wherein, The usage amount of the photocatalyst is 0.4 - 0.9 weight parts.

4. The pressure-sensitive adhesive for yellowing-resistant TPU vehicle wraps according to claim 2, wherein, The preparation raw materials of the arylamine photocatalyst include at least: 10 - 30 mL of glacial acetic acid, 500 - 550 mg of diphenylamine, 2 - 3 mg of cesium carbonate, 10 - 30 mL of toluene, and 90 - 100 mg of palladium catalyst. The preparation raw materials also include dibromobenzoyl and aminobenzene.

5. The pressure-sensitive adhesive for yellowing-resistant TPU vehicle wraps according to claim 4, wherein The dibromobenzoyl is selected from at least one of 4,4-dibromobenzoyl, 2,4-dibromobenzoyl, 2,5-dibromobenzoyl, or 2,6-dibromobenzoyl.

6. The pressure-sensitive adhesive for yellowing-resistant TPU vehicle wraps according to claim 4, characterized in that, The aminobenzene is selected from at least one of 1,2-phenylenediamine or 2,2-diaminobiphenyl.

7. The pressure-sensitive adhesive for yellowing-resistant TPU vehicle wrap according to claim 4, characterized in that, The usage amount of the dibromobenzoyl is 1072 - 1872 mg, and the usage amount of the aminobenzene is 332 - 532 mg.

8. The pressure-sensitive adhesive for yellowing-resistant TPU vehicle wrap according to claim 4, characterized in that, The preparation method of the photocatalyst includes the following steps: S1 Mix dibromobenzoyl, aminobenzene, and glacial acetic acid, reflux for 2 - 5 h under an inert gas atmosphere, cool to room temperature, perform vacuum distillation to obtain a crude product, purify by chromatography, and vacuum dry to obtain an intermediate product; S2 Mix the intermediate product, diphenylamine, cesium carbonate, toluene, and palladium catalyst, reflux for 10 - 20 h under an inert gas atmosphere, cool to room temperature, perform vacuum distillation, purify by chromatography, and vacuum dry to obtain the photocatalyst.

9. The pressure-sensitive adhesive for yellowing-resistant TPU vehicle wrap according to claim 1, wherein, The solvent includes Solvent Ⅰ, Solvent Ⅱ, Solvent Ⅲ, and Solvent Ⅳ. Solvent Ⅰ, Solvent Ⅱ, Solvent Ⅲ, and Solvent Ⅳ are each selected from at least one of ethyl acetate, toluene, N,N-dimethylformamide, dimethyl sulfoxide, acetone, or isopropanol.

10. A preparation method of the yellowing-resistant pressure-sensitive adhesive for TPU vehicle wraps according to claim 9, characterized in that, It includes the following steps: M1: After mixing Solvent Ⅰ evenly, heat under reflux and maintain at 85 - 90 °C to obtain Component A; M2: Mix the photocatalyst, soft monomer, hard monomer, functional monomer, Solvent Ⅱ, and 60 - 70 wt% of the initiator evenly to obtain Component B; Mix Solvent Ⅲ and the remaining initiator evenly to obtain Component C; Mix Solvent Ⅳ, curing agent, and inhibitor evenly to obtain Component D; M3: Dropwise add Component B into Component A, with the dropping time being 120 - 150 min, and keep warm for 50 - 70 min after dropping; M4: After keeping warm, dropwise add Component C, with the dropping time being 10 - 15 min, and keep warm for 150 - 200 min after dropping; M5: After keeping warm, stop heating, cool to below 40 °C, dropwise add Component D, with the dropping time being 20 - 40 min, and stir for 30 - 40 min after dropping to obtain the yellowing-resistant TPU car wrap pressure-sensitive adhesive.

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