High-temperature-resistant advertising paper, preparation method thereof and high-temperature-resistant polyurethane adhesive

Abstract

The application relates to the technical field of advertising paper, and particularly discloses a high-temperature-resistant advertising paper, a preparation method thereof and a high-temperature-resistant polyurethane adhesive. The high-temperature-resistant advertising paper comprises an aluminum foil layer and environment-friendly isolation paper, the aluminum foil layer and the environment-friendly isolation paper are bonded by the high-temperature-resistant polyurethane adhesive; the high-temperature-resistant polyurethane adhesive is composed of polyurethane resin, anti-aging agent, leveling agent, defoaming agent, modified inorganic heat-resistant flame retardant and water; the preparation method comprises the following steps: stirring and mixing the polyurethane resin and the water, then adding the anti-aging agent, the leveling agent, the defoaming agent and the modified heat-resistant flame retardant, and stirring and mixing to obtain the high-temperature-resistant polyurethane adhesive; coating the high-temperature-resistant polyurethane adhesive on the surface of the aluminum foil layer, then arranging the environment-friendly isolation paper, and thus the high-temperature-resistant advertising paper is obtained. The high-temperature-resistant advertising paper disclosed by the application does not deform and turn yellow at 250 DEG C for 6 hours, can be applied to high-temperature places such as electric heating panels and outdoor wall decoration, and has good high-temperature resistance and flame retardation.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of advertising paper, in particular to a high-temperature-resistant advertising paper and a preparation method thereof and a high-temperature-resistant polyurethane adhesive. BACKGROUND

[0002] Advertising paper is a kind of paper designed for advertising, which has various types, each of which has specific characteristics and purposes to meet different advertising needs.

[0003] PVC advertising paper is a classic advertising paper material, which has the characteristics of water resistance, ultraviolet resistance, strong flexibility and difficulty in tearing. Therefore, PVC advertising paper is often used in exhibition boards, light box advertising and other scenes.

[0004] Because in a high-temperature environment, the movement between PVC molecules will accelerate, which may cause the polymer chain to break and initiate thermal decomposition. Therefore, when PVC advertising paper is applied in high-temperature scenes such as electric heating panels or outdoor wall decoration materials, the PVC advertising paper is prone to deformation, color yellowing, and even melting, which greatly reduces the aesthetic and durability of the advertisement. SUMMARY

[0005] In order to improve the high-temperature resistance of the advertising paper, the application provides a high-temperature-resistant advertising paper, a preparation method thereof and a high-temperature-resistant polyurethane adhesive.

[0006] In a first aspect, the application provides a high-temperature-resistant advertising paper, which adopts the following technical solution:

[0007] A high-temperature-resistant advertising paper, comprising an aluminum foil layer and an environmentally friendly release paper, wherein the aluminum foil layer and the environmentally friendly release paper are bonded by a high-temperature-resistant polyurethane adhesive;

[0008] The high-temperature-resistant polyurethane adhesive is composed of the following components by weight percentage:

[0009] Polyurethane resin 38-45%;

[0010] Anti-aging agent 2-4%;

[0011] Leveling agent 4-6%;

[0012] Defoaming agent 1-3%;

[0013] Modified inorganic heat-resistant flame retardant 3-5;

[0014] Water 41-50%;

[0015] The preparation method of the modified inorganic heat-resistant flame retardant comprises the following steps:

[0016] A1: stirring and mixing the amino silane coupling agent and the aqueous ethanol solution, adding the mixture of inorganic heat-resistant agent and inorganic flame retardant, and stirring and mixing to obtain a silane-modified mixture;

[0017] A2: adding chitosan and epoxy resin into the silane-modified mixture, and stirring and mixing to obtain a heat-resistant and flame-retardant modifier.

[0018] The silanol generated after the hydrolysis of the amino silane coupling agent can be bonded with the hydroxyl groups on the surface of the inorganic heat-resistant agent and the inorganic flame retardant, thereby grafting the amino groups on the surface of the inorganic heat-resistant agent and the inorganic flame retardant. Since the chitosan contains a large number of hydroxyl groups and the epoxy resin contains a large number of epoxy groups, the amino groups in the silane-modified mixture can react with the hydroxyl groups in the chitosan and the epoxy groups in the epoxy resin, thereby obtaining the modified inorganic heat-resistant and flame-retardant agent grafted with the chitosan and the epoxy resin on the surface.

[0019] By adopting the above technical solutions, the chitosan with biocompatibility and the epoxy resin with heat resistance are grafted on the surface of the inorganic heat-resistant and flame-retardant agent, the compatibility and dispersibility of the modified inorganic heat-resistant and flame-retardant agent in the polyurethane resin are improved, and the polyurethane adhesive has high heat resistance and flame retardance. Meanwhile, the wrought aluminum foil used for the aluminum foil layer also has good heat resistance. Therefore, the advertising paper made of the polyurethane adhesive, the aluminum foil layer and the environment-friendly release paper has good high-temperature resistance and flame retardance, does not deform and turn yellow at 250°C for 6 hours, can be applied in high-temperature places such as electric heating panels and outdoor wall decoration, has a service life of 15 years, and does not have the safety hazard of easy ignition and combustion during use.

[0020] Preferably, in the preparation method of the modified inorganic heat-resistant and flame-retardant agent, the weight ratio of the mixture, the amino silane coupling agent, the chitosan, the epoxy resin and the aqueous ethanol solution is 1:(0.38-0.56):(0.15-0.22):(0.08-0.16):(2-5).

[0021] By adopting the above technical solutions, the modified heat-resistant and flame-retardant agent prepared by mixing in the above weight ratio is grafted with the silane coupling agent, the chitosan and the epoxy resin on the surface, has good hydrophilicity and lipophilicity, is easy to disperse in the polyurethane resin and has high compatibility, and can effectively improve the heat resistance and flame retardance of the prepared adhesive.

[0022] Preferably, in the preparation method of the modified inorganic heat-resistant and flame-retardant agent, the weight ratio of the mixture, the amino silane coupling agent, the chitosan, the epoxy resin and the aqueous ethanol solution is 1:(0.40-0.52):0.20:(0.10-0.14):4.

[0023] By adopting the technical scheme, by increasing the amount of amino silane coupling agent and epoxy resin, a large amount of amino silane coupling agent and epoxy resin is subjected to ring-opening reaction, a large amount of heat-resistant three-dimensional network structure film layer is formed on the surface of the modified heat-resistant flame retardant, and the heat resistance of the prepared adhesive is improved.

[0024] Preferably, in the preparation method of the modified inorganic heat-resistant flame retardant, the epoxy resin is alicyclic epoxy resin.

[0025] By adopting the technical scheme, since the epoxy groups in the alicyclic epoxy resin are directly connected to the alicyclic ring, the three-dimensional network structure formed after the ring-opening of the amino and epoxy groups has a large density and a large rigid structure, and has higher thermal stability, thereby improving the heat resistance of the prepared adhesive.

[0026] Preferably, the alicyclic epoxy resin has a viscosity of 300-450 cps at 25 DEG C and an epoxy equivalent weight of 131-143 g / Eq.

[0027] By adopting the technical scheme, the alicyclic epoxy resin has a high glass transition temperature and good processing performance, the film layer formed on the surface of the modified heat-resistant flame retardant has excellent thermal stability, and the heat resistance of the prepared adhesive is improved.

[0028] Preferably, in the heat-resistant polyurethane adhesive, the polyurethane resin is anionic aliphatic waterborne polyurethane dispersion, has a viscosity of 50-2000 mPa s, a pH value of 6-8, and a solid content of 44-46.

[0029] By adopting the technical scheme, the anionic aliphatic waterborne polyurethane dispersion has the advantages of fast initial adhesion speed, high bonding strength, and high thermal stability, and has high compatibility with the raw materials of the modified heat-resistant flame retardant. Therefore, the adhesive prepared by using the anionic aliphatic waterborne polyurethane dispersion as the main raw material has high heat resistance, flame retardance, and bonding performance.

[0030] Preferably, in the heat-resistant polyurethane adhesive, the inorganic flame retardant is white silver flame retardant.

[0031] By adopting the technical scheme, the white silver flame retardant, especially the white silver special flame retardant magnesium hydroxide, is a high-purity magnesium hydroxide produced by chemical synthesis, has a regular hexagonal flake structure, a narrow particle size distribution, and good dispersion of single crystals, has good flame retardance, and is easy to be subjected to silane surface treatment.

[0032] In the second aspect, the application provides a preparation method of heat-resistant advertising paper, which adopts the following technical scheme:

[0033] A preparation method of a high-temperature-resistant advertising paper, comprising the following steps:

[0034] S1: stirring and mixing polyurethane resin and water at 90-95 DEG C for 3-4 h, cooling to 30-35 DEG C, then adding anti-aging agent, leveling agent, defoaming agent and modified heat-resistant flame retardant, stirring and mixing to obtain high-temperature-resistant polyurethane adhesive;

[0035] S2: coating the high-temperature-resistant polyurethane adhesive on the surface of the aluminum foil layer, and setting the environment-friendly release paper on the side of the aluminum foil layer coated with the high-temperature-resistant polyurethane adhesive, thereby obtaining the high-temperature-resistant advertising paper.

[0036] By using the above technical scheme, the polyurethane resin and water are fully mixed at 90-95 DEG C, which is conducive to the compatibility and dispersion of the modified heat-resistant flame retardant and other raw materials in the polyurethane resin aqueous solution, and the polyurethane adhesive uniformly dispersed with the modified heat-resistant flame retardant is obtained, and the polyurethane adhesive layer formed after curing on the aluminum foil has good high-temperature resistance and flame retardance.

[0037] In a third aspect, the application provides a high-temperature-resistant polyurethane adhesive, which adopts the following technical scheme:

[0038] A high-temperature-resistant polyurethane adhesive, which is composed of the following components by weight percentage:

[0039] Polyurethane resin 38-45%;

[0040] Anti-aging agent 2-4%;

[0041] Leveling agent 4-6%;

[0042] Defoaming agent 1-3%;

[0043] Modified inorganic heat-resistant flame retardant 3-5;

[0044] Water 41-50%;

[0045] The preparation method of the modified inorganic heat-resistant flame retardant comprises the following steps:

[0046] A1: stirring and mixing amino silane coupling agent and ethanol aqueous solution, then adding a mixture of inorganic heat-resistant agent and inorganic flame retardant, stirring and mixing to obtain a silane-modified mixture;

[0047] A2: adding chitosan and epoxy resin into the silane-modified mixture, stirring and mixing to obtain a heat-resistant flame-retardant modifier.

[0048] By adopting the above technical solution, on the one hand, chitosan, with its good biocompatibility, can improve the compatibility of modified inorganic heat-resistant flame retardants in polyurethane resins, allowing the modified inorganic heat-resistant flame retardants to be uniformly dispersed in the polyurethane resins and less prone to precipitation, which is beneficial to improving the heat resistance and flame retardant properties of the prepared adhesives. On the other hand, the three-dimensional network structure formed by the reaction of amino groups and epoxy resins has high thermal stability and is not easily decomposed, which is beneficial to improving the heat resistance of the prepared adhesives.

[0049] Meanwhile, epoxy resin has good hydrophobicity. By grafting chitosan and epoxy resin onto the surface of the modified inorganic heat-resistant flame retardant, it can achieve both hydrophilicity and hydrophobicity, thus exhibiting good compatibility and dispersibility in polar resins. This can further improve the heat resistance and flame retardant properties of the prepared adhesive.

[0050] In summary, this application has the following beneficial effects:

[0051] 1. Since the aluminum foil and polyurethane adhesive used in this application have good heat resistance, the high-temperature resistant advertising paper prepared by bonding the aluminum foil layer and the environmentally friendly release paper with polyurethane adhesive has excellent high-temperature resistance and can be used in high-temperature places without deformation or yellowing.

[0052] 2. The method for preparing high-temperature resistant advertising paper in this application involves thoroughly mixing all the raw materials in the polyurethane adhesive, coating it onto the surface of aluminum foil, and then setting an environmentally friendly release paper. The preparation method is simple and suitable for large-scale production.

[0053] 3. This application grafts chitosan and epoxy resin onto the surface of inorganic heat resistant agents and inorganic flame retardants. Because chitosan has good biocompatibility, epoxy resin can form a thermally stable three-dimensional network structure after ring-opening reaction. Therefore, the inorganic heat resistant and flame retardant has good compatibility and dispersibility in polyurethane resin and is not easy to precipitate after curing, which is beneficial to improving the high temperature resistance of the cured polyurethane adhesive. Detailed Implementation

[0054] The present application will be further described in detail below with reference to the embodiments.

[0055] Unless otherwise specified below, all raw materials used in the embodiments of this application are commercially available.

[0056] The aminosilane coupling agent is 3-aminopropylmethyldimethoxysilane;

[0057] An aqueous solution of ethanol with a mass fraction of 75%;

[0058] Inorganic heat resistant agent, hydrophilic nano-silica, content 99.6%, 3000 mesh;

[0059] Inorganic flame retardant, specifically magnesium hydroxide for Baiyin special flame retardants, with magnesium hydroxide content ≥99.0%, silicon dioxide content ≤0.1%, acid-insoluble matter ≤0.05%, particle size D50 <1.5μm, moisture ≤0.5%, chloride ion content ≤0.1%, iron ion content ≤0.005%, and specific surface area ≤8m². 2 / g, whiteness > 97;

[0060] Chitosan, industrial grade, with a degree of deacetylation of 85%, loss on drying ≤12%, pH value 6.5-8.5, and insoluble matter ≤2%.

[0061] Preparation Example

[0062] Preparation Example 1

[0063] A modified inorganic heat-resistant flame retardant, the raw materials and their corresponding weights (kg) are shown in the table below.

[0064]

[0065] The preparation method of the above-mentioned modified inorganic heat-resistant flame retardant includes the following steps:

[0066] A1: After stirring and mixing the aminosilane coupling agent and the ethanol aqueous solution for 20 min, add the mixture of inorganic heat resistant agent and inorganic flame retardant, and stir and mix at 400 r / min for 30 min to obtain the silane modified mixture;

[0067] A2: Add chitosan to the silane-modified mixture, stir and mix at 600 r / min for 10 min, then add epoxy resin and stir and mix for 30 min to obtain a temperature-resistant flame-retardant modifier.

[0068] In the preparation example of this application, the epoxy resin is designated Syna-Epoxy 21, with a viscosity of 300-450 cps at 25°C and an epoxy equivalent of 131-143 g / Eq.

[0069] Preparation Examples 2-5

[0070] A modified inorganic heat-resistant flame retardant, which differs from Preparation Example 1 in that the raw materials and their corresponding weights (kg) are shown in the table below.

[0071]

[0072] Preparation Example 6

[0073] A modified inorganic heat-resistant flame retardant, which differs from Preparation Example 1 in that the epoxy resin is designated Syna-Epoxy27, has a viscosity of ≤20 cps at 25°C, and an epoxy equivalent of 105–120 g / Eq.

[0074] Preparation Example 7

[0075] A modified inorganic heat-resistant flame retardant, which differs from Preparation Example 1 in that the epoxy resin is Wuxi Phoenix brand epoxy resin 618, with a viscosity of 1000 mPas and an epoxy equivalent of 184-195 g / Eq.

[0076] Preparation Example 8

[0077] A modified inorganic heat-resistant flame retardant, differing from Preparation Example 1 in that the preparation method of the inorganic heat-resistant flame retardant includes the following steps:

[0078] A1: After stirring and mixing the aminosilane coupling agent and the ethanol aqueous solution for 20 min, add the mixture of inorganic heat resistant agent and inorganic flame retardant, and stir and mix at 400 r / min for 30 min to obtain the silane modified mixture;

[0079] A2: Add epoxy resin to the silane-modified mixture, stir and mix at 600 r / min for 10 min, then add chitosan and stir and mix for 30 min to obtain a temperature-resistant flame-retardant modifier.

[0080] Preparation Example 9

[0081] A modified inorganic heat-resistant flame retardant, which differs from Preparation Example 1 in that an equal weight of waterborne polyamide resin is used instead of epoxy resin, wherein the waterborne polyamide resin is an anionic aliphatic waterborne polyurethane dispersion with a viscosity of 50-2000 mPa·s, a pH value of 6-8, and a solid content of 44-46%.

[0082] Example

[0083] Example 1

[0084] A high-temperature resistant advertising paper includes an aluminum foil layer and an environmentally friendly release paper, which are bonded together by a high-temperature resistant polyurethane adhesive.

[0085] The components and their corresponding weights (kg) of the above-mentioned high-temperature resistant polyurethane adhesive are shown in the table below.

[0086]

[0087] The preparation method of the above-mentioned high-temperature resistant advertising paper includes the following steps:

[0088] S1: Polyurethane resin and water are stirred and mixed at 90-95°C (90°C in this application example) for 3-4 hours (4 hours in this application example), then cooled to 30-35°C, and then antioxidant, leveling agent, defoamer and modified heat-resistant flame retardant are added and stirred to obtain high-temperature resistant polyurethane adhesive.

[0089] In this embodiment, the polyurethane resin is... PU-645 is an anionic aliphatic waterborne polyurethane dispersion with a viscosity of 50–2000 mPa·s, a pH of 6–8, and a solid content of 44–46%.

[0090] S2: Apply high-temperature resistant polyurethane adhesive to the surface of the aluminum foil layer, and then place environmentally friendly release paper on the side of the aluminum foil layer coated with high-temperature resistant polyurethane adhesive to obtain high-temperature resistant advertising paper.

[0091] Examples 2-3

[0092] A high-temperature resistant advertising paper, which differs from Example 1 in that the components and their corresponding weights (kg) of the above-mentioned high-temperature resistant polyurethane adhesive are shown in the table below.

[0093]

[0094] Examples 4-10

[0095] A high-temperature resistant advertising paper, which differs from Example 1 in that the modified inorganic heat-resistant flame retardant is prepared using the preparation examples in the table below.

[0096]

[0097] Comparative Example

[0098] Comparative Example 1

[0099] A type of PVC advertising paper, available commercially.

[0100] Comparative Example 2

[0101] An advertising paper differs from Example 1 in that it uses an equal weight of inorganic heat-resistant flame retardant instead of modified inorganic heat-resistant flame retardant, wherein the inorganic heat-resistant flame retardant is composed of an inorganic heat resistant agent and an inorganic flame retardant mixed in a weight ratio of 1:1.

[0102] Comparative Example 3

[0103] An advertising paper, which differs from Example 1 in that the modified inorganic heat-resistant flame retardant is prepared by Preparation Example 9.

[0104] Performance testing

[0105] 1. The high-temperature resistance performance of the high-temperature resistant advertising paper prepared in the embodiments of this application and the PVC advertising paper of Comparative Example 1 were tested. The testing method was as follows:

[0106] After tearing off the environmentally friendly release paper from the high-temperature resistant advertising paper, place it together with the PVC advertising paper in a 250℃ oven for 6 hours and test whether the high-temperature resistant advertising paper or the advertising paper will deform or yellow.

[0107] The performance test results are shown in the table below:

[0108]

[0109] Data analysis of the table above shows that the high-temperature resistant advertising papers prepared in Examples 1-11 of this application do not deform or yellow after being placed in a 250℃ oven for 6 hours. In contrast, the PVC advertising paper prepared in Comparative Example 1 deforms and yellows after being placed in a 250℃ oven for 6 hours. This indicates that the high-temperature resistant advertising papers prepared in Examples 1-11 of this application have high high-temperature resistance and can be used in high-temperature applications such as electric heating panels and outdoor wall decorations.

[0110] 2. The high-temperature resistant polyurethane adhesives prepared in the embodiments and comparative examples of this application were subjected to shear strength and flame retardant performance tests. The test methods are as follows:

[0111] Shear strength: After curing the high-temperature resistant polyurethane adhesive at 85℃ / 85%RH for 7 days, it was placed in a 120℃ oven for 24 hours, and then its shear strength was tested in a 120℃ high and low temperature tensile tester.

[0112] Flame retardant performance: Samples were prepared according to standard ANSI / UL 94-1985, and the flame retardant rating was tested according to the UL94 vertical burning test standard.

[0113] The performance test results are shown in the table below:

[0114]

[0115] Data analysis of the table above shows that the high-temperature resistant polyurethane adhesives prepared in Examples 1, 4, and 5 have higher shear strength than those prepared in Examples 6 and 7. This indicates that when the weight ratio of the modified inorganic heat-resistant flame retardant mixture, aminosilane coupling agent, chitosan, epoxy resin, and ethanol aqueous solution in the total raw materials for preparing the high-temperature resistant polyurethane adhesive of this application is 1:(0.40~0.52):0.20:(0.10~0.14):4, the high-temperature resistance of the high-temperature resistant polyurethane adhesive can be improved.

[0116] Compared to the high-temperature resistant polyurethane adhesives prepared using alicyclic epoxy resins in Examples 1 and 8, the high-temperature resistant polyurethane adhesive prepared using bisphenol A epoxy resin in Example 9 exhibits a significantly reduced shear strength. This indicates that using alicyclic epoxy resin to prepare a modified inorganic heat-resistant flame retardant in the total raw materials for preparing the high-temperature resistant polyurethane adhesive of this application can improve the high-temperature resistance of the adhesive.

[0117] Compared to the high-temperature resistant polyurethane adhesive prepared using a modified inorganic heat-resistant and flame-retardant agent in Example 1, the high-temperature resistant polyurethane adhesive prepared using a mixture of inorganic heat-resistant agent and inorganic flame-retardant agent in Comparative Example 2 has a relatively lower shear strength of 23.24% and a flame retardant rating of V-2.

[0118] Compared to the modified inorganic heat-resistant flame retardant prepared with chitosan and epoxy resin in Example 1, the modified inorganic heat-resistant flame retardant prepared with chitosan and waterborne polyamide resin in Comparative Example 3 showed a 15.68% decrease in shear strength and a reduction in flame retardant rating to V-1. This indicates that modifying the inorganic heat-resistant agent and inorganic flame retardant with chitosan and epoxy resin in the total raw materials for preparing the high-temperature resistant polyurethane adhesive of this application can improve the high-temperature resistance of the high-temperature resistant polyurethane adhesive.

[0119] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A high-temperature resistant advertising paper, characterized in that, It includes an aluminum foil layer and an environmentally friendly release paper, which are bonded together by a high-temperature resistant polyurethane adhesive; The high-temperature resistant polyurethane adhesive is composed of the following components by weight percentage: Polyurethane resin 38-45%; Anti-aging agent 2-4%; Leveling agent 4-6%; Defoamer 1-3%; Modified inorganic heat-resistant flame retardant 3-5; Water content: 41-50%; The preparation method of the modified inorganic heat-resistant flame retardant includes the following steps: A1: After stirring and mixing the aminosilane coupling agent and the ethanol aqueous solution, add the mixture of inorganic heat resistant agent and inorganic flame retardant, stir and mix to obtain a silane modified mixture; A2: Add chitosan and epoxy resin to the silane-modified mixture, stir and mix to obtain a temperature-resistant flame-retardant modifier; The inorganic heat-resistant agent is hydrophilic nano-silica; The inorganic flame retardant is magnesium hydroxide, a special flame retardant for silver.

2. The high-temperature resistant advertising paper according to claim 1, characterized in that, In the preparation method of the modified inorganic heat-resistant flame retardant, the weight ratio of the mixture, aminosilane coupling agent, chitosan, epoxy resin and ethanol aqueous solution is 1:(0.38~0.56):(0.15~0.22):(0.08~0.16):(2~5).

3. The high-temperature resistant advertising paper according to claim 2, characterized in that, In the preparation method of the modified inorganic heat-resistant flame retardant, the weight ratio of the mixture, aminosilane coupling agent, chitosan, epoxy resin and ethanol aqueous solution is 1:(0.40~0.52):0.20:(0.10~0.14):

4.

4. The high-temperature resistant advertising paper according to claim 1, characterized in that, In the preparation method of the modified inorganic heat-resistant flame retardant, the epoxy resin is an alicyclic epoxy resin.

5. The high-temperature resistant advertising paper according to claim 4, characterized in that, The alicyclic epoxy resin has a viscosity of 300-450 cps at 25°C and an epoxy equivalent of 131-143 g / Eq.

6. The high-temperature resistant advertising paper according to claim 1, characterized in that, In the high-temperature resistant polyurethane adhesive, the polyurethane resin is an anionic aliphatic waterborne polyurethane dispersion with a viscosity of 50–2000 mPa·s, a pH value of 6–8, and a solid content of 44–46%.

7. The method for preparing the high-temperature resistant advertising paper according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1: After stirring and mixing polyurethane resin and water at 90-95℃ for 3-4 hours, cool to 30-35℃, then add antioxidant, leveling agent, defoamer and modified heat-resistant flame retardant, stir and mix to obtain high-temperature resistant polyurethane adhesive. S2: Apply high-temperature resistant polyurethane adhesive to the surface of the aluminum foil layer, and then place environmentally friendly release paper on the side of the aluminum foil layer coated with high-temperature resistant polyurethane adhesive to obtain high-temperature resistant advertising paper.

8. A high-temperature resistant polyurethane adhesive, characterized in that, It consists of the following components by weight percentage: Polyurethane resin 38-45%; Anti-aging agent 2-4%; Leveling agent 4-6%; Defoamer 1-3%; Modified inorganic heat-resistant flame retardant 3-5; Water content: 41-50%; The preparation method of the modified inorganic heat-resistant flame retardant includes the following steps: A1: After stirring and mixing the aminosilane coupling agent and the ethanol aqueous solution, add the mixture of inorganic heat resistant agent and inorganic flame retardant, stir and mix to obtain a silane modified mixture; A2: Add chitosan and epoxy resin to the silane-modified mixture, stir and mix to obtain a temperature-resistant flame-retardant modifier; The inorganic heat-resistant agent is hydrophilic nano-silica; The inorganic flame retardant is magnesium hydroxide, a special flame retardant for silver.

Images