A waterproof and heat-resistant color-printed composite packaging paper and its preparation method

Abstract

The present invention discloses a waterproof and heat-resistant color-printed composite packaging paper and a preparation method thereof, which relates to the technical field of color-printed composite packaging paper. The preparation method includes the following steps: S1: Composite aluminum foil on both sides of the cardboard; S2: Composite color-printed pages on the surfaces of the aluminum foil on both sides of the cardboard; S3: Composite PVC films on the surfaces of the color-printed pages on both sides of the cardboard; S4: Coat a waterproof and heat-resistant coating on the surfaces of the PVC films on both sides of the cardboard, heat to 80-85 °C, and dry for 12-16 h to obtain the color-printed composite packaging paper; the waterproof and heat-resistant coating is prepared from non-isocyanate polythiourethane, POSS-tricyclic thiocarbonate and polyetheramine; during the preparation process of the color-printed composite packaging paper, adhesives are coated between the cardboard and the aluminum foil, between the aluminum foil and the color-printed pages, and between the color-printed pages and the PVC films, and composite processing is carried out by means of hot pressing.

Description

Technical Field

[0001] The present invention relates to the technical field of color printing composite packaging paper, and specifically to a waterproof and heat-resistant color printing composite packaging paper and a preparation method thereof. Background Art

[0002] In recent years, with the diversification of consumer demands and the improvement of environmental protection awareness, the demand for high-performance and environmentally friendly packaging materials has gradually increased. Due to the limitations of its base materials and coatings, traditional color printing composite packaging paper often has problems of insufficient waterproofness and heat resistance, and it is difficult to meet the requirements for packaging paper under high humidity and high temperature conditions. Although commonly used coating materials such as isocyanate polyurethane and polyhydroxy polyurethane have good mechanical properties and adhesion properties, they also have certain defects: phosgene, which is toxic, needs to be used in the synthesis process of isocyanate, posing a safety hazard; while polyhydroxy polyurethane usually has poor waterproof performance due to the influence of the hydroxyl structure. At the same time, bisphenol A epoxy resin, as an important component of traditional epoxy resin, has potential health risks, forcing researchers to look for more environmentally friendly alternatives.

[0003] Therefore, it is of great significance to invent a waterproof and heat-resistant coating for color printing composite packaging paper. Summary of the Invention

[0004] The purpose of the present invention is to provide a waterproof and heat-resistant color printing composite packaging paper and a preparation method thereof to solve the problems raised in the prior art.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] A preparation method of a waterproof and heat-resistant color printing composite packaging paper: including the following steps S1: laminating aluminum foil on both sides of the cardboard;

[0007] S2: laminating color printing pages on the surfaces of the aluminum foil on both sides of the cardboard;

[0008] S3: laminating PVC films on the surfaces of the color printing pages on both sides of the cardboard;

[0009] S4: coating a waterproof and heat-resistant coating on the surfaces of the PVC films on both sides of the cardboard, heating to 80 - 85 °C, and drying for 12 - 16 h to obtain the color printing composite packaging paper;

[0010] Further, the coating thickness of the waterproof and heat-resistant coating is 20 - 30 μm;

[0011] Further, the waterproof and heat-resistant coating is prepared from non-isocyanate polythiourethane, POSS-tricyclic thiocarbonate, and polyetheramine;

[0012] Further, during the preparation of the color-printed composite packaging paper, an adhesive is coated between the cardboard and the aluminum foil, between the aluminum foil and the color-printed page, and between the color-printed page and the PVC film, and the composite processing is carried out by means of hot pressing.

[0013] Further, the adhesive includes ACTEBond ASB-908.

[0014] Further, the preparation method of the waterproof and heat-resistant coating includes the following steps: adding non-isocyanate polythiourethane and POSS-tricyclic thiocarbonate into a container, adding a catalyst solution, stirring evenly, adding a polyetheramine solution, and stirring evenly to obtain the waterproof and heat-resistant coating.

[0015] Further, during the preparation of the waterproof and heat-resistant coating, the mass ratio of non-isocyanate polythiourethane: POSS-tricyclic thiocarbonate: polyetheramine is (2.0 - 3.49):(0.6 - 1.2):(1.4 - 2.21).

[0016] Further, the solvents of the catalyst solution and the polyetheramine solution are both tetrahydrofuran;

[0017] Further, the concentration of the catalyst solution is 1 wt%, and the catalyst is 1,8-diazabicyclo[5.4.0]undec-7-ene;

[0018] Further, the preparation method of the non-isocyanate polythiourethane includes the following steps:

[0019] Adding bio-based epoxy resin and lithium bromide into tetrahydrofuran, stirring evenly, adding carbon disulfide, stirring and reacting for 48 - 72 h under ice bath conditions, rotary evaporation, washing with ethyl acetate and deionized water, and vacuum drying at 60 - 80 °C for 48 h to obtain non-isocyanate polythiourethane.

[0020] Further, during the preparation of the non-isocyanate polythiourethane, the molar ratio of bio-based epoxy resin: lithium bromide: carbon disulfide is 1:1:2.2.

[0021] Further, the preparation method of the bio-based epoxy resin includes the following steps:

[0022] Adding gallic acid, epichlorohydrin and tetrabutylammonium bromide into a reaction vessel, adding 20 wt% aqueous sodium hydroxide solution under stirring, heating to 100 - 105 °C and reacting for 4 - 4.5 h, washing the solution with deionized water until neutral, rotary evaporation and drying to obtain bio-based epoxy resin.

[0023] Further, during the preparation of the bio-based epoxy resin, the molar ratio of gallic acid: epichlorohydrin is 1:20.

[0024] Furthermore, the preparation method of the POSS-tricyclic thiocarbonate comprises the following steps: step (1): adding phenyltrimethoxysilane, sodium hydroxide and deionized water to tetrahydrofuran, heating to 70-75°C for reaction for 4-4.5h, cooling to room temperature for reaction for 15-16h, rotary evaporation, and vacuum drying at 40-42°C for 24h to obtain heptaphenylsilsesquioxane trisodium silanol salt; adding heptaphenylsilsesquioxane trisodium silanol salt to tetrahydrofuran, adding dimethylchlorosilane under ice bath condition, heating to room temperature for reaction for 24h, filtering, rotary evaporation, adding methanol for precipitation, and vacuum drying the solid product at 40-42°C for 24h to obtain POSS-trihydrogen;

[0025] Step (2): POSS-3H and allyl glycidyl ether are added to toluene, purged with nitrogen for 30-45 min, Karstedt catalyst is added, heated to 90-92° C. for reaction for 36-48 h, cooled to room temperature, rotary evaporated, the product is extracted with dichloromethane, and vacuum dried at 40-42° C. for 48 h to obtain POSS-triepoxide;

[0026] Step (3): Add POSS-triepoxide and lithium bromide to tetrahydrofuran, stir evenly, add carbon disulfide, stir and react in an ice bath for 24-48 hours, rotary evaporate, wash with ethyl acetate and deionized water, extract the product with dichloromethane, and vacuum dry at 40-42° C. for 48 hours to obtain POSS-tricyclic thiocarbonate.

[0027] Furthermore, in the preparation process of the POSS-trihydrogen, the proportions of the components by mass include: 45-50 parts of phenyltrimethoxysilane, 0.96-1.04 parts of sodium hydroxide, 5.26-5.54 parts of deionized water, and 27.79-28.12 parts of dimethylchlorosilane;

[0028] Furthermore, in the preparation process of the POSS-triepoxide compound, the proportions of the components by mass include: 10-12.44 parts of POSS-3H, 6.16-6.36 parts of allyl glycidyl ether, and 0.03-0.04 parts of Karstedt catalyst;

[0029] Furthermore, in the preparation process of the POSS-tricyclic thiocarbonate, the molar ratio of POSS-triepoxide: lithium bromide: carbon disulfide is 1:1:2.2.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The present invention uses non-isocyanate polythiourethane, POSS-tricyclic thiocarbonate, and polyetheramine as raw materials to prepare a coating with excellent waterproof and fireproof properties to meet the requirements of waterproof and heat-resistant properties of color-printed composite packaging paper. Different from traditional isocyanate polyurethane and polyhydroxy polyurethane, the non-isocyanate polythiourethane prepared in the present invention has no safety hazard of toxic phosgene in the synthesis process of isocyanate in traditional isocyanate polyurethane raw materials, nor does it have the problem of poor waterproof performance caused by a large number of hydroxyl groups in the polyhydroxy polyurethane structure. Using natural renewable resource gallic acid as a raw material, through epoxidation treatment, a bio-based epoxy resin containing four epoxy groups is prepared, aiming to replace traditional bisphenol A epoxy resin and develop a more environmentally friendly and healthier alternative to isocyanate polyurethane and polyhydroxy polyurethane.

[0032] 2. Different from the problem in the preparation process of polyhydroxy polyurethane that the conversion rate of the five-membered cyclic carbonate pendant group of epoxy resin is slow and the conversion is incomplete, resulting in incomplete curing, long curing time, and low cross-linking degree of the subsequent coating during the curing process; in the present invention, through the fixation of carbon disulfide, the epoxy groups in the epoxy resin are converted into five-membered cyclic dithiocarbonate, and then react with amino groups to form thiocarbamate. Since the five-membered cyclic dithiocarbonate has a larger and more favorable ring strain, compared with the oxygen analogue five-membered cyclic carbonate, the five-membered cyclic dithiocarbonate has stronger reactivity with nucleophiles, which enables the reaction to proceed relatively quickly under milder conditions, greatly improving the cross-linking density and curing rate.

[0033] 3. In the present invention, by introducing self-made POSS-tricyclic thiocarbonate into the coating, on the one hand, the waterproof and heat-resistant properties of the coating are improved; on the other hand, due to the multi-epoxy groups of gallic acid epoxy resin and the multi-amino structure of polyetheramine, the coating curing process has a high cross-linking density. The addition of POSS-tricyclic thiocarbonate can greatly improve the toughness of the coating, achieving the purpose of enhancing toughness, tensile strength, and glass transition temperature. Detailed implementation manners

[0034] Next, the technical solutions in the embodiments of the present invention will be described clearly and completely in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0035] In the following examples, the specifications of bisphenol A epoxy resin: E51, purchased from Hangzhou Wuhuigang Adhesive Co., Ltd.; the cardboard specifications are kraft paper, purchased from Nine Dragons Paper; the aluminum foil is purchased from Shandong Zhongbo Aluminum Industry Technology Co., Ltd.; the PVC film specifications: the thickness is 0.30 mm, purchased from Foshan Bona Color Decoration Materials Co., Ltd.; the rest of the raw materials are commercially available.

[0036] In the following examples, the preparation method of the bio-based epoxy resin includes the following steps:

[0037] Add 1 mol of gallic acid, 20 mol of epichlorohydrin, and 0.4 g of tetrabutylammonium bromide to a reaction vessel, add 20 wt% sodium hydroxide aqueous solution under stirring, heat to 100 °C and react for 4 h, wash the solution with deionized water until neutral, rotary evaporate and dry to obtain bio-based epoxy resin.

[0038] In the following examples, the preparation method of the non-isocyanate polythiourethane includes the following steps:

[0039] Add 1 mol of bio-based epoxy resin and 1 mol of lithium bromide to 50 mL of tetrahydrofuran, stir evenly, add 2.2 mol of carbon disulfide, stir and react for 48 h under ice bath conditions, rotary evaporate, wash with ethyl acetate and deionized water, and vacuum dry at 80 °C for 48 h to obtain non-isocyanate polythiourethane.

[0040] In the following examples, the preparation method of the POSS-tricyclic thiocarbonate includes the following steps: Step (1): Add 45 parts of phenyltrimethoxysilane, 0.96 part of sodium hydroxide, and 5.26 parts of deionized water to 250 mL of tetrahydrofuran, heat to 70 °C and react for 4 h, cool to room temperature and react for 15 h, rotary evaporate, vacuum dry at 4 °C for 24 h to obtain heptaphenylsilsesquioxane trisodium silanolate; add heptaphenylsilsesquioxane trisodium silanolate to tetrahydrofuran, add 27.79 parts of dimethylchlorosilane under ice bath conditions, heat to room temperature and react for 24 h, filter, rotary evaporate, add methanol for precipitation, and vacuum dry the solid product at 40 °C for 24 h to obtain POSS-3H;

[0041] Step (2): Add 10 parts of POSS-3H and 6.16 parts of allyl glycidyl ether to 100 mL of toluene, purge with nitrogen for 30 min, add 0.03 part of Karstedt catalyst, heat to 90 °C and react for 36 h, cool to room temperature, rotary evaporate, extract the product with dichloromethane, and vacuum dry at 40 °C for 48 h to obtain POSS-tricyclic epoxide;

[0042] Step (3): Add 1 mol of POSS-trisepoxide and 1 mol of lithium bromide into tetrahydrofuran, stir evenly, add 2.2 mol of carbon disulfide, stir and react for 24 h under ice bath conditions, perform rotary evaporation, wash with ethyl acetate and deionized water, extract the product with dichloromethane, and dry in vacuum at 40 °C for 48 h to obtain POSS-tricyclic thiocarbonate.

[0043] Example 1: A preparation method of a waterproof and heat-resistant color-printed composite packaging paper: S1: Composite aluminum foil on both sides of the cardboard;

[0044] S2: Composite color-printed pages on the surfaces of the aluminum foils on both sides of the cardboard;

[0045] S3: Composite PVC films on the surfaces of the color-printed pages on both sides of the cardboard;

[0046] S4: Add 2 g of non-isocyanate polythiourethane and 0.6 g of POSS-tricyclic thiocarbonate into a container, add a tetrahydrofuran solution containing 0.05 g of 1,8-diazabicyclo[5.4.0]undec-7-ene, stir evenly, add a tetrahydrofuran solution containing 1.4 g of polyetheramine, stir evenly to obtain a waterproof and heat-resistant coating;

[0047] S5: Coat the waterproof and heat-resistant coating on the surfaces of the PVC films on both sides of the cardboard, with a coating thickness of 20 μm, heat to 80 °C, and dry for 12 h to obtain the color-printed composite packaging paper.

[0048] Example 2: A preparation method of a waterproof and heat-resistant color-printed composite packaging paper: S1: Composite aluminum foil on both sides of the cardboard;

[0049] S2: Composite color-printed pages on the surfaces of the aluminum foils on both sides of the cardboard;

[0050] S3: Composite PVC films on the surfaces of the color-printed pages on both sides of the cardboard;

[0051] S4: Add 2.78 g of non-isocyanate polythiourethane and 0.96 g of POSS-tricyclic thiocarbonate into a container, add a tetrahydrofuran solution containing 0.06 g of 1,8-diazabicyclo[5.4.0]undec-7-ene, stir evenly, add a tetrahydrofuran solution containing 1.78 g of polyetheramine, stir evenly to obtain a waterproof and heat-resistant coating;

[0052] S5: Coat the waterproof and heat-resistant coating on the surfaces of the PVC films on both sides of the cardboard, with a coating thickness of 20 μm, heat to 80 °C, and dry for 12 h to obtain the color-printed composite packaging paper.

[0053] Example 3: A preparation method of a waterproof and heat-resistant color-printed composite packaging paper: S1: Composite aluminum foil on both sides of the cardboard;

[0054] S2: Composite color printed pages on the aluminum foil surfaces on both sides of the cardboard;

[0055] S3: Composite PVC films on the color printed page surfaces on both sides of the cardboard;

[0056] S4: Add 3.49 g of non-isocyanate polythiourethane and 1.2 g of POSS-tricyclic thiocarbonate into a container, add a tetrahydrofuran solution containing 0.06 g of 1,8-diazabicyclo[5.4.0]undec-7-ene, stir evenly, add a tetrahydrofuran solution containing 2.21 g of polyetheramine, stir evenly to obtain a waterproof and heat-resistant coating;

[0057] S5: Coat the waterproof and heat-resistant coating on the PVC film surfaces on both sides of the cardboard, with a coating thickness of 20 μm, heat to 80 °C, and dry for 12 h to obtain a color printed composite wrapping paper.

[0058] Comparative Example 1: A preparation method of a waterproof and heat-resistant color printed composite wrapping paper: The preparation method of the non-isocyanate polythiourethane includes the following steps:

[0059] Add 1 mol of bisphenol A epoxy resin and 1 mol of lithium bromide into 50 mL of tetrahydrofuran, stir evenly, add 2.2 mol of carbon disulfide, stir and react for 48 h under ice bath conditions, perform rotary evaporation, wash with ethyl acetate and deionized water, and vacuum dry at 80 °C for 48 h to obtain non-isocyanate polythiourethane;

[0060] S1: Composite aluminum foil on both sides of the cardboard;

[0061] S2: Composite color printed pages on the aluminum foil surfaces on both sides of the cardboard;

[0062] S3: Composite PVC films on the color printed page surfaces on both sides of the cardboard;

[0063] S4: Add 2 g of non-isocyanate polythiourethane and 0.6 g of POSS-tricyclic thiocarbonate into a container, add a tetrahydrofuran solution containing 0.05 g of 1,8-diazabicyclo[5.4.0]undec-7-ene, stir evenly, add a tetrahydrofuran solution containing 1.4 g of polyetheramine, stir evenly to obtain a waterproof and heat-resistant coating;

[0064] S5: Coat the waterproof and heat-resistant coating on the PVC film surfaces on both sides of the cardboard, with a coating thickness of 20 μm, heat to 80 °C, and dry for 12 h to obtain a color printed composite wrapping paper.

[0065] Comparative Example 2: A preparation method of a waterproof and heat-resistant color printed composite wrapping paper: The preparation method of the non-isocyanate polythiourethane includes the following steps:

[0066] Add 10 g of bio-based epoxy resin to N,N-dimethylformamide, add 2.38 g of tetrabutylammonium bromide, heat to 80 °C, introduce carbon dioxide, keep the temperature for reaction for 80 h, wash with vinyl acetate and deionized water, rotary evaporate at 60 °C, and vacuum dry at 80 °C to obtain polyhydroxy polyurethane;

[0067] S1: Laminate aluminum foil on both sides of the cardboard;

[0068] S2: Laminate color printing pages on the surfaces of the aluminum foil on both sides of the cardboard;

[0069] S3: Laminate PVC film on the surfaces of the color printing pages on both sides of the cardboard;

[0070] S4: Add 2 g of polyhydroxy polyurethane and 0.6 g of POSS-tricyclic thiocarbonate to a container, add a tetrahydrofuran solution containing 0.05 g of 1,8-diazabicyclo[5.4.0]undec-7-ene, stir evenly, add a tetrahydrofuran solution containing 1.4 g of polyetheramine, and stir evenly to obtain a waterproof and heat-resistant coating;

[0071] S5: Coat the waterproof and heat-resistant coating on the surfaces of the PVC film on both sides of the cardboard, with a coating thickness of 20 μm, heat to 80 °C, and dry for 12 h to obtain a color printing composite packaging paper.

[0072] Comparative Example 3: A preparation method of a waterproof and heat-resistant color printing composite packaging paper: The preparation method of the POSS-tricyclic thiocarbonate includes the following steps: Step (1): Add 45 parts of phenyltrimethoxysilane, 0.96 part of sodium hydroxide, and 5.26 parts of deionized water to 250 mL of tetrahydrofuran, heat to 70 °C and react for 4 h, cool to room temperature and react for 15 h, rotary evaporate, and vacuum dry at 4 °C for 24 h to obtain heptaphenylsilsesquioxane trisodium silanolate; Add heptaphenylsilsesquioxane trisodium silanolate to tetrahydrofuran, add 27.79 parts of dimethylchlorosilane under ice bath conditions, heat to room temperature and react for 24 h, filter, rotary evaporate, add methanol for precipitation, and place the solid product in a vacuum at 40 °C for 24 h to obtain POSS-3H;

[0073] Step (2): Add 10 parts of POSS-3H and 6.16 parts of allyl glycidyl ether to 100 mL of toluene, purge with nitrogen for 30 min, add 0.03 part of Karstedt catalyst, heat to 90 °C and react for 36 h, cool to room temperature, rotary evaporate, extract the product with dichloromethane, and vacuum dry at 40 °C for 48 h to obtain POSS-tricyclic epoxide;

[0074] Step (3): 13 g of POSS-triepoxide, 0.5 g of tetra-n-butylammonium iodide, 0.45 g of 1,3-bis(hexafluoro-2-hydroxyisopropyl)benzene, and 15 mL of anhydrous toluene were introduced, nitrogen was passed through, heated to 80 °C, the pressure was increased to 6 MPa, reacted for 48 h, cooled to room temperature, the solvent was removed, and extracted with dichloromethane to obtain POSS-trimercaptopolyurethane.

[0075] S1: The aluminum foil was laminated on both sides of the cardboard;

[0076] S2: The color printing pages were laminated on the surfaces of the aluminum foils on both sides of the cardboard;

[0077] S3: The PVC films were laminated on the surfaces of the color printing pages on both sides of the cardboard;

[0078] S4: 2 g of polyhydroxy polyurethane and 0.6 g of POSS-trimercaptopolyurethane were added to a container, a tetrahydrofuran solution containing 0.05 g of 1,8-diazabicyclo[5.4.0]undec-7-ene was added and stirred evenly, a tetrahydrofuran solution containing 1.4 g of polyetheramine was added and stirred evenly to obtain a waterproof and heat-resistant coating;

[0079] S5: The waterproof and heat-resistant coating was coated on the surfaces of the PVC films on both sides of the cardboard, with a coating thickness of 20 μm, heated to 80 °C, and dried for 12 h to obtain a color-printed composite packaging paper.

[0080] Comparative Example 4: A method for preparing a waterproof and heat-resistant color-printed composite packaging paper: S1: The aluminum foil was laminated on both sides of the cardboard;

[0081] S2: The color printing pages were laminated on the surfaces of the aluminum foils on both sides of the cardboard;

[0082] S3: The PVC films were laminated on the surfaces of the color printing pages on both sides of the cardboard;

[0083] S4: 4.22 g of non-isocyanate polythiourethane and 0.6 g of POSS-trithiocarbonate were added to a container, a tetrahydrofuran solution containing 0.05 g of 1,8-diazabicyclo[5.4.0]undec-7-ene was added and stirred evenly, a tetrahydrofuran solution containing 1.4 g of polyetheramine was added and stirred evenly to obtain a waterproof and heat-resistant coating;

[0084] S5: The waterproof and heat-resistant coating was coated on the surfaces of the PVC films on both sides of the cardboard, with a coating thickness of 20 μm, heated to 80 °C, and dried for 12 h to obtain a color-printed composite packaging paper.

[0085] Comparative Example 5: A method for preparing a waterproof and heat-resistant color-printed composite packaging paper: S1: The aluminum foil was laminated on both sides of the cardboard;

[0086] S2: The color printing pages were laminated on the surfaces of the aluminum foils on both sides of the cardboard;

[0087] S3: Laminate the surfaces of the color-printed pages on both sides of the cardboard with PVC films;

[0088] S4: Put 2 g of non-isocyanate polythiourethane and 0.4 g of POSS-tricyclic thiocarbonate into a container, add a tetrahydrofuran solution containing 0.05 g of 1,8-diazabicyclo[5.4.0]undec-7-ene, stir evenly, add a tetrahydrofuran solution containing 1.4 g of polyetheramine, and stir evenly to obtain a waterproof and heat-resistant coating;

[0089] S5: Coat the waterproof and heat-resistant coating on the surfaces of the PVC films on both sides of the cardboard, with a coating thickness of 20 μm, heat to 80 °C, and dry for 12 h to obtain a color-printed composite wrapping paper.

[0090] Experiment: Water absorption test: Immerse the color-printed composite wrapping paper samples of the above-mentioned examples and comparative examples in deionized water, take them out after soaking at room temperature for 72 h, wipe the water stains on the surface, weigh the samples, and calculate the water absorption rate;

[0091] Water absorption rate (%) = (weight after soaking - weight before soaking) / weight before soaking × 100%.

[0092] Coat the waterproof and heat-resistant coating prepared in the above-mentioned examples and comparative examples on a polytetrafluoroethylene plate to prepare a coating sample of 30 × 5 × 1 mm for mechanical property testing.

[0093] Mechanical property test: The tensile test is carried out at room temperature, using a universal testing machine, and the tensile rate is 130 mm / min.

[0094] Glass transition temperature test: Measure the glass transition temperature of the coating sample by dynamic mechanical thermal analysis.

[0095] The experimental data are shown in Table 1 below.

[0096] Table 1 Data table of performance test

[0097] Water absorption rate / % Tensile strength / MPa Glass transition temperature / °C Example 1 3.1 28.1 51.2 Example 2 2.4 31.6 53.5 Example 3 1.8 33.5 56.1 Comparative example 1 6.4 24.1 43.2 Comparative example 2 5.6 25.7 45.6 Comparative example 3 5.1 26.5 48.1 Comparative example 4 3.5 22.1 48.5 Comparative example 5 4.9 24.6 44.9

[0098] Conclusion: The waterproof and heat-resistant coating prepared by the present invention has excellent waterproof and heat-resistant properties, and the color-printed composite wrapping paper prepared with it also has excellent waterproof and heat-resistant properties.

[0099] In Comparative Example 1, replacing the bio-based epoxy resin with a traditional bisphenol A epoxy resin resulted in a decrease in water absorption, tensile strength, and glass transition temperature; in Comparative Example 2, replacing the non-isocyanate polythiourethane with a polyhydroxy polyurethane led to a decrease in various properties; in Comparative Example 3, replacing the POSS-tricyclic thiocarbonate with a POSS-tricyclic hydroxyurethane resulted in a decrease in various properties; in Comparative Example 4, an increase in the amount of non-isocyanate polythiourethane led to an increase in crosslink density and a decrease in various properties; in Comparative Example 5, a decrease in the content of POSS-tricyclic thiocarbonate led to a decrease in various properties.

[0100] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced by the present invention. Any reference signs in the claims should not be construed as limiting the claims concerned.

Claims

1. A preparation method of a waterproof and heat-resistant color-printed composite packaging paper, characterized in that: It includes the following steps: S1: Composite aluminum foil on both sides of the cardboard; S2: Composite color printing pages on the surfaces of the aluminum foils on both sides of the cardboard; S3: Composite PVC films on the surfaces of the color printing pages on both sides of the cardboard; S4: Coat a waterproof and heat-resistant coating on the surfaces of the PVC films on both sides of the cardboard, heat to 80 - 85 °C, and dry for 12 - 16 h to obtain a color-printed composite packaging paper; The coating thickness of the waterproof and heat-resistant coating is 20 - 30 μm; The waterproof and heat-resistant coating is prepared from non-isocyanate polythiourethane, POSS-tricyclic thiocarbonate, and polyetheramine; During the preparation process of the color-printed composite packaging paper, adhesives are coated between the cardboard and the aluminum foil, between the aluminum foil and the color printing page, and between the color printing page and the PVC film, and they are composite by hot pressing.

2. The preparation method of a waterproof and heat-resistant color-printed composite packaging paper according to claim 1, characterized in that: The preparation method of the waterproof and heat-resistant coating includes the following steps: Add non-isocyanate polythiourethane and POSS-tricyclic thiocarbonate into a container, add a catalyst solution, stir evenly, add a polyetheramine solution, and stir evenly to obtain the waterproof and heat-resistant coating.

3. The preparation method of a waterproof and heat-resistant color printing composite packaging paper according to claim 2, characterized in that: During the preparation process of the waterproof and heat-resistant coating, the mass ratio of non-isocyanate polythiourethane:POSS-tricyclic thiocarbonate:polyetheramine is (2.0 - 3.49):(0.6 - 1.2):(1.4 - 2.21).

4. The preparation method of a waterproof and heat-resistant color-printed composite packaging paper according to claim 2, characterized in that: The preparation method of the non-isocyanate polythiourethane includes the following steps: Add bio-based epoxy resin and lithium bromide into tetrahydrofuran, stir evenly, add carbon disulfide, stir and react for 48 - 72 h under ice bath conditions, rotary evaporate, wash with ethyl acetate and deionized water, and vacuum dry at 60 - 80 °C for 48 h to obtain non-isocyanate polythiourethane.

5. The preparation method of a waterproof and heat-resistant color printing composite packaging paper according to claim 4, characterized in that: During the preparation process of non-isocyanate polythiourethane, the molar ratio of bio-based epoxy resin:lithium bromide:carbon disulfide is 1:1:2.

2.

6. The preparation method of a waterproof and heat-resistant color printing composite packaging paper according to claim 4, characterized in that: The preparation method of the bio-based epoxy resin includes the following steps: Add gallic acid, epichlorohydrin, and tetrabutylammonium bromide into a reaction container, add 20 wt% sodium hydroxide aqueous solution under stirring, heat to 100 - 105 °C and react for 4 - 4.5 h, wash the solution with deionized water until neutral, rotary evaporate and dry to obtain bio-based epoxy resin.

7. The preparation method of a waterproof and heat-resistant color printing composite packaging paper according to claim 6, characterized in that: During the preparation process of bio-based epoxy resin, the molar ratio of gallic acid:epichlorohydrin is 1:

20.

8. The preparation method of a waterproof and heat-resistant color printing composite packaging paper according to claim 2, wherein: The preparation method of the POSS-tricyclic thiocarbonate includes the following steps: Step (1): Add phenyltrimethoxysilane, sodium hydroxide, and deionized water into tetrahydrofuran, heat to 70 - 75 °C and react for 4 - 4.5 h, cool to room temperature and react for 15 - 16 h, rotary evaporate, and vacuum dry at 40 - 42 °C for 24 h to obtain heptaphenylsilsesquioxane trisodium silanolate; Add heptaphenylsilsesquioxane trisodium silanolate into tetrahydrofuran, under ice bath conditions, add dimethylchlorosilane, heat to room temperature and react for 24 h, filter, rotary evaporate, add methanol to precipitate, and place the solid product in a vacuum drying environment at 40 - 42 °C for 24 h to obtain POSS-trihydrogen; Step (2): Add POSS-3H and allyl glycidyl ether into toluene, purge with nitrogen for 30 - 45 min, add Karstedt catalyst, heat to 90 - 92 °C and react for 36 - 48 h, cool to room temperature, rotary evaporate, extract the product with dichloromethane, and vacuum dry at 40 - 42 °C for 48 h to obtain POSS-tricyclic epoxide; Step (3): Add POSS-tricyclic epoxide and lithium bromide into tetrahydrofuran, stir evenly, add carbon disulfide, stir and react under ice bath conditions for 24 - 48 h, rotary evaporate, wash with ethyl acetate and deionized water, extract the product with dichloromethane, and vacuum dry at 40 - 42 °C for 48 h to obtain POSS-tricyclic thiocarbonate.

9. The preparation method of a waterproof and heat-resistant color-printed composite packaging paper according to claim 8, characterized in that: In the preparation process of POSS-trihydrogen, the proportion of each component by mass fraction includes: 45 - 50 parts of phenyltrimethoxysilane, 0.96 - 1.04 parts of sodium hydroxide, 5.26 - 5.54 parts of deionized water, and 27.79 - 28.12 parts of dimethylchlorosilane; In the preparation process of POSS-tricyclic epoxide, the proportion of each component by mass fraction includes: 10 - 12.44 parts of POSS-3H, 6.16 - 6.36 parts of allyl glycidyl ether, and 0.03 - 0.04 parts of Karstedt catalyst; In the preparation process of POSS-tricyclic thiocarbonate, the molar ratio of POSS-tricyclic epoxide: lithium bromide: carbon disulfide is 1:1:2.

2.

10. A color-printed composite packaging paper prepared by the preparation method of a waterproof and heat-resistant color-printed composite packaging paper according to any one of claims 1 - 9.