Water-based coating for special PP synthetic paper for dye ink with high heat laminating film adhesion and preparation method thereof

Abstract

The present application relates to the technical field of photographic paper coating, and particularly relates to a water-based coating for dye ink special PP synthetic photographic paper for increasing the film covering firmness of hot mounting film and a preparation method thereof, the water-based coating for dye ink special PP synthetic photographic paper for increasing the film covering firmness of hot mounting film contains the following components in 100% by mass: modified silicon dioxide 10-20%, polyvinyl alcohol 25-35%, polyurethane-acrylic hybrid emulsion 8-15%, nano boehmite 2.5-3.5%, dispersant 1.5-2.5%, thickening agent 0.5-0.7%, leveling agent 0.2-0.4%, defoaming agent 0.3-0.5%, expanding agent 2-4%, accelerator 0.5-1.5%, mildew-proof agent 0.1-0.3%, ammonia water 0.1-0.3%, and the rest is deionized water. The water-based coating prepared by the present application has good ink absorbability, strong film covering firmness after hot mounting film covering, and high ink adaptability.

Description

Technical Field

[0001] This invention relates to the field of photographic paper coating technology, specifically to a water-based coating for dye-based PP synthetic photographic paper that enhances the adhesion of heat-mounted films and inks, and its preparation method. Background Technology

[0002] In fields such as digital imaging, advertising production, and home decoration, PP synthetic photo paper, with its advantages of strong weather resistance, high flatness, and controllable cost, has gradually replaced traditional photo paper as one of the mainstream substrates for dye-based ink printing. As the market demands higher decorative effects and longer shelf life for printed materials, the application frequency of thermal lamination, a key post-processing step to enhance the abrasion resistance, water resistance, and color stability of photo paper, continues to increase. However, current PP synthetic photo paper specifically designed for dye-based inks faces numerous problems in practical use. For example, insufficient compatibility between the surface coating performance and thermal lamination, or the migration of some additives in the dye-based ink to the printed layer surface after drying, can significantly reduce the surface tension of the layer, resulting in low lamination adhesion and easy edge lifting and local peeling after lamination. Simultaneously, insufficient ink absorption in some coatings also seriously affects the lifespan and visual presentation of printed materials, becoming a core bottleneck restricting the application of PP synthetic photo paper in mid-to-high-end printing fields.

[0003] Patent CN104629608B discloses a coating solution for preparing inkjet high-gloss waterproof photographic paper. The coating solution comprises: 10-40 parts by weight of toner absorbent, 30-55 parts by weight of adhesive, 0.05-0.15 parts by weight of whitening agent, 0.05-0.15 parts by weight of dispersant, 2-5 parts by weight of defoamer, 1-3 parts by weight of neutralizing agent, and 140-200 parts by weight of distilled water; the adhesive is a cationic aqueous polyurethane emulsion. The patent also discloses photographic paper prepared using this coating solution and its preparation method. This coating solution is non-toxic and odorless, possesses good adhesion and waterproof properties, and exhibits good weather resistance, allowing it to withstand long-term sunlight exposure. The coating has high internal structural strength, good adhesion to the substrate, and good scratch resistance on the printed surface. The photographic paper prepared by this invention has a particularly fast drying speed after ink absorption, producing clear and sharp images; vibrant colors and high color fidelity, with no ink buildup; and excellent waterproof performance.

[0004] Patent CN115820017A discloses a water-based high-gloss coating for photographic paper and its preparation method. The coating is made from the following components in the indicated weight percentages: 35-45% methyl methacrylate, 10-15% isocyanate, 11-18% water-based polyamide resin, 3-8% sodium dodecylbenzenesulfonate, 3-8% diacetone, 3-5% fumed silica, 1-3% wetting agent, 0.1-2% defoamer, 1-5% ammonia, and the balance being deionized water. The preparation method includes crosslinking, ammoniation, filling, and mixing. The coated photographic paper produced by this invention achieves the gloss of laminated photographic paper, and its water resistance and ink absorption are better than those of laminated products on the market, making it a complete replacement. Compared with other coated products, it also has the advantage of high gloss. The resulting coated photographic paper has a bright surface and vivid, clear patterns. Moreover, this coating material is completely degradable in soil, producing no toxic or harmful substances, making it more environmentally friendly.

[0005] While the coatings in the above patents improve ink absorption, they do not correspondingly improve lamination adhesion. Therefore, there is an urgent need in the market for a water-based coating for PP synthetic photo paper specifically designed for dye inks that can increase the lamination adhesion of heat-laminated paper. Summary of the Invention

[0006] In view of the problems existing in the prior art, the purpose of this invention is to obtain a water-based coating that can not only increase the adhesion of heat lamination film, but also has good ink absorption.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] This invention provides a water-based coating for PP synthetic photographic paper specifically designed for dye-based inks, which enhances the adhesion of heat-mounted films. The coating, by weight percentage (100%), comprises the following components: 10-20% modified silica, 25-35% polyvinyl alcohol, 8-15% polyurethane-acrylic hybrid emulsion, 2.5-3.5% nano-boehmite, 1.5-2.5% dispersant, 0.5-0.7% thickener, 0.2-0.4% leveling agent, 0.3-0.5% defoamer, 2-4% swelling agent, 0.5-1.5% accelerator, 0.1-0.3% mildew inhibitor, 0.1-0.3% ammonia, with the balance being deionized water.

[0009] In some embodiments, the method for preparing the modified silica includes the following steps:

[0010] Add silica and silane coupling agent to methanol solution, stir at room temperature for 40-50 min, then add 1-amino-5-hexen-2-ol, adjust pH to 10-12, and react at 60-70℃ for 8-9 h to obtain modified silica.

[0011] In some embodiments, the silica has a particle size of 5-12 μm.

[0012] Preferably, the silane coupling agent is γ-glycidoxypropyltrimethoxysilane.

[0013] In some embodiments, the mass ratio of the silica to 1-amino-5-hexen-2-ol is 1:(0.08-0.15).

[0014] Adding silica to coatings can enhance the ink absorption and film adhesion of the coating. However, due to the poor dispersibility of silica, secondary particles are easily formed, leading to uneven coating and affecting printing quality and final film effect. First, this invention preferably uses silica with a suitable particle size for silane modification. This increases the compatibility of silica with other raw materials in the system and avoids the problems of weak adsorption of additives in dye inks due to excessively small particle size, which affects the printing effect, and excessively large particle size, which leads to uneven printing patterns and easy peeling and cracking. Second, 1-amino-5-hexen-2-ol is further reacted with a silane coupling agent to graft double bonds and hydroxyl groups on the silica surface, enabling it to disperse evenly in deionized water. At the same time, it can further react with polyurethane-acrylic hybrid emulsion to increase the crosslinking degree of the system, improve the film-forming effect of the coating, and improve printing quality.

[0015] In some embodiments, the method for preparing the polyurethane-acrylic hybrid emulsion includes the following steps:

[0016] (1) Add pentaerythritol triacrylate, N-vinylimidazolium and initiator to methanol, react at 65-75℃ for 1-2 h, filter, wash and dry to obtain polymer;

[0017] (2) Add polyether polyol, polyisocyanate, chain extender and catalyst to the reaction vessel and react at 75-85℃ for 4-6h to obtain prepolymer. Then cool down to 55-65℃, add polymer obtained in step (1), continue to cool down to 35-45℃, add neutralizer, react for 5-15min, add deionized water and stir, then add initiator, emulsifier and acrylic acid and react at 65-75℃ for 2-3h to obtain polyurethane-acrylic hybrid emulsion.

[0018] This invention utilizes the reaction of pentaerythritol triacrylate with N-vinylimidazole to form a branched polymer. Adding this polymer to the polyurethane preparation process yields a novel waterborne polyurethane-acrylic hybrid emulsion. This emulsion not only improves lamination strength but also exhibits high adhesion to PP substrate paper and excellent ink compatibility. The likely reason is that the imidazole rings grafted onto the polymer chain possess strong polarity and reactivity. They can form strong hydrogen bonds and coordination bonds with the polar groups in the adhesives used for heat lamination, allowing for easier penetration and anchoring within the adhesive layer of the heat-laminated film. Under hot-pressing conditions, this forms a microscopic interpenetrating network, achieving a "hook-anchor" type mechanical interlocking, resulting in a strong lamination. The adhesion between the coating and the PP substrate is improved; at the same time, the branched structure provides more contact points and entanglement possibilities, which can effectively combine with the oxygen-containing polar groups generated after corona treatment on the PP surface, further strengthening the adhesion between the coating and the PP substrate and preventing peeling; in addition, there are a large number of hydrophilic groups in the tight cross-linked network, which can quickly absorb water in the dye ink, prevent ink droplet diffusion, and improve printing accuracy. The dense coating provides a stable fixation platform for the dye ink, further preventing surfactants, lubricants and other additives in the dye ink from migrating to the ink film surface after drying and film formation, forming a physical isolation layer or lubrication layer, which would reduce the lamination strength of the heat-laminated film.

[0019] In some embodiments, the chain extender is a mixture of 1,4-butanediol and dimethylolpropionic acid in a mass ratio of (0.6-0.9):1.

[0020] In some embodiments, the mass ratio of pentaerythritol triacrylate to N-vinylimidazole is 1:(0.16-0.3).

[0021] In some embodiments, the mass ratio of the polyether polyol to the polymer in step (2) is 1:(0.07-0.13).

[0022] In some embodiments, the nanoboehmite has a particle size of 5-15 nm.

[0023] In some embodiments, the degree of alcoholysis of the polyvinyl alcohol is 87-89 mol.

[0024] The second aspect of this invention provides a method for preparing a water-based coating for dye-based PP synthetic photographic paper that enhances the heat lamination adhesion, comprising the following steps:

[0025] Polyvinyl alcohol is added to a portion of deionized water, heated to 40-50℃ and stirred for 30-60 minutes. Then, the remaining deionized water, modified silica, and polyurethane-acrylic hybrid emulsion are added and stirred at 60-70℃ for 1-2 hours. Finally, nano-boehmite, dispersant, thickener, leveling agent, defoamer, expanding agent, accelerator, mildew inhibitor, and ammonia are added and stirred at room temperature for 1-2 hours to obtain a water-based coating.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The present invention prepares a water-based coating for dye ink-specific PP synthetic photographic paper suitable for increasing the heat lamination fastness by modifying silica, polyurethane-acrylic hybrid emulsion and other additives.

[0028] (2) In this invention, silica with a suitable particle size is preferred for silane modification, which increases the compatibility of silica with other raw materials in the system. At the same time, it avoids the problem that if the particle size is too small, the adsorption of the auxiliary agents in the dye ink will be weak, affecting the printing effect. If the particle size is too large, the printed pattern will not be delicate and will easily fall off and crack. Secondly, 1-amino-5-hexen-2-ol is used to further react with silane coupling agent to graft double bonds and hydroxyl groups on the surface of silica so that it can be evenly dispersed in deionized water. At the same time, it can further react with polyurethane-acrylic hybrid emulsion to increase the crosslinking degree of the system, improve the film-forming effect of the coating, and improve the printing quality.

[0029] (3) The present invention forms a branched polymer by reacting pentaerythritol triacrylate with N-vinylimidazole and adding it to the preparation process of polyurethane to obtain a novel waterborne polyurethane-acrylic hybrid emulsion that not only improves the film strength but also has high adhesion to PP substrate paper and excellent ink compatibility. Detailed Implementation

[0030] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0031] In the following examples and comparative examples, all compounds and related reagents used were commercially available. Specifically, silica with an average particle size of 10 μm was purchased from Qinghe County Ruijiang Metal Materials Co., Ltd.; silica with an average particle size of 3 μm was purchased from Donghai County Fucai Mineral Products Co., Ltd.; the polyether diol was DL-2000D; the thickener was ASE-60, brand Rohm and Haas; the leveling agent was BYK-349, and the defoamer was BYK-024, both brand BYK; the expanding agent was Acronal® PLUS8590, brand BASF; the mildew inhibitor was Acticide® MBS5050, brand Toll; and the nanoboehmite had an average particle size of 10 nm.

[0032] Preparation Example 1

[0033] The preparation method of modified silica-1 includes the following steps:

[0034] 10g of silica (average particle size 10μm) and 2g of γ-glycidoxypropyltrimethoxysilane were added to 100ml of 95wt% methanol solution and stirred at room temperature for 45min. Then 1g of 1-amino-5-hexen-2-ol was added, the pH was adjusted to 11 with sodium hydroxide, and the reaction was carried out at 65℃ for 8.5h to obtain modified silica-1.

[0035] Preparation Example 2

[0036] The preparation method of modified silica-2 is the same as that in preparation example 1, except that the amount of 1-amino-5-hexen-2-ol added is 2g.

[0037] Preparation Example 3

[0038] The preparation method of modified silica-3 is the same as that in preparation example 1, except that the particle size of silica is 3 μm.

[0039] Preparation Example 4

[0040] The preparation method of polyurethane-acrylic hybrid emulsion-1 includes the following steps:

[0041] (1) 10g pentaerythritol triacrylate, 2.4g N-vinylimidazolium and 0.12g azobisisobutyronitrile were added to 100ml anhydrous methanol and reacted at 70℃ for 1.5h. The mixture was then filtered, washed and dried to obtain the polymer.

[0042] (2) 100g of polyether diol, 60g of hexamethylene diisocyanate, 2.4g of 1,4-butanediol, 3g of dimethylolpropionic acid and 0.1g of dibutyltin dilaurate were added to the reaction vessel and reacted at 80℃ for 5h to obtain a prepolymer. Then the temperature was lowered to 60℃, 10g of the polymer obtained in step (1) was added, and the temperature was further lowered to 40℃. 2.1g of triethylamine was added and reacted for 10min. Deionized water was added and stirred at 1500rpm for 30min. Then 1.6g of azobisisobutyronitrile, 1.5g of sodium dodecyl sulfate and 40g of acrylic acid were added and reacted at 70℃ for 2.5h to obtain polyurethane-acrylic hybrid emulsion-1.

[0043] Preparation Example 5

[0044] The preparation method of polyurethane-acrylic hybrid emulsion-2 is the same as that of preparation example 4, except that the amount of N-vinylimidazole added is 3.5g.

[0045] Preparation Example 6

[0046] The preparation method of polyurethane-acrylic hybrid emulsion-3 is the same as that of preparation example 4, except that the amount of polymer added is 16g.

[0047] Preparation Example 7

[0048] The preparation method of polyurethane-acrylic hybrid emulsion-4 is the same as that of preparation example 4, except that pentaerythritol triacrylate is replaced with methyl methacrylate in equal amounts.

[0049] Preparation Example 7

[0050] The preparation method of polyurethane-acrylic hybrid emulsion-5 includes the following steps:

[0051] 100g of polyether diol, 60g of hexamethylene diisocyanate, 2.4g of 1,4-butanediol, 3g of dimethylolpropionic acid, and 0.1g of dibutyltin dilaurate were added to a reaction vessel and reacted at 80℃ for 5h to obtain a prepolymer. Then, the temperature was lowered to 60℃, 10g of pentaerythritol triacrylate was added, and the temperature was further lowered to 40℃. 2.1g of triethylamine was added, and the reaction was carried out for 10min. Deionized water was added and stirred at 1500rpm for 30min. Then, 1.6g of azobisisobutyronitrile, 1.5g of sodium dodecyl sulfate, and 40g of acrylic acid were added, and the reaction was carried out at 70℃ for 2.5h to obtain polyurethane-acrylic hybrid emulsion-5.

[0052] Example 1

[0053] A water-based coating for PP synthetic photographic paper with dye inks that enhances the adhesion of heat-mounted films contains the following components by weight percentage (100%): modified silica-1 15%, PVA1788 27%, polyurethane-acrylic hybrid emulsion-1 10%, nano-boehmite 3%, PEG-1000 2%, thickener 0.6%, leveling agent 0.3%, defoamer 0.4%, expanding agent 3%, N-methyldiethanolamine 1%, mildew inhibitor 0.2%, 25wt% ammonia water 0.2%, and the balance being deionized water.

[0054] The method for preparing the water-based coating for dye-based ink-specific PP synthetic photographic paper to enhance the heat lamination adhesion of this embodiment includes the following steps:

[0055] Add PVA1788 to half of the mass of deionized water, heat to 45℃ and stir for 45 min, then add the remaining deionized water, modified silica-1, and polyurethane-acrylic hybrid emulsion-1 and stir at 65℃ for 1.5 h. Finally, add nano boehmite, PEG-1000, thickener, leveling agent, defoamer, expanding agent, N-methyldiethanolamine, mildew inhibitor, and 25wt% ammonia water and stir at room temperature for 1.5 h to obtain the water-based coating.

[0056] Example 2

[0057] A water-based coating for dye-based PP synthetic photographic paper that enhances the adhesion of heat-mounted films contains the following components by weight percentage (100%): modified silica-1 10%, PVA1788 25%, polyurethane-acrylic hybrid emulsion 18%, nano-boehmite 2.5%, PEG-1000 1.5%, thickener 0.5%, leveling agent 0.2%, defoamer 0.3%, expanding agent 2%, N-methyldiethanolamine 0.5%, mildew inhibitor 0.1%, 25wt% ammonia water 0.1%, and the balance being deionized water.

[0058] The method for preparing the water-based coating for dye-based ink-specific PP synthetic photographic paper to enhance the heat lamination adhesion of this embodiment includes the following steps:

[0059] Add half the mass of PVA1788 to deionized water, heat to 40℃ and stir for 60 min. Then add the remaining deionized water, modified silica-1, and polyurethane-acrylic hybrid emulsion-1 and stir at 60℃ for 2 h. Finally, add nano boehmite, PEG-1000, thickener, leveling agent, defoamer, expanding agent, N-methyldiethanolamine, mildew inhibitor, and 25wt% ammonia water and stir at room temperature for 1 h to obtain water-based coating.

[0060] Example 3

[0061] A water-based coating for PP synthetic photographic paper with dye inks, designed to enhance the adhesion of heat-mounted films, comprises the following components by weight percentage (100%): modified silica-1 20%, PVA1788 35%, polyurethane-acrylic hybrid emulsion-1 15%, nano-boehmite 3.5%, PEG-1000 2.5%, thickener 0.7%, leveling agent 0.4%, defoamer 0.5%, expanding agent 4%, N-methyldiethanolamine 1.5%, mildew inhibitor 0.3%, 25wt% ammonia water 0.3%, with the balance being deionized water.

[0062] The method for preparing the water-based coating for dye-based ink-specific PP synthetic photographic paper to enhance the heat lamination adhesion of this embodiment includes the following steps:

[0063] Add half the mass of PVA1788 to deionized water, heat to 50℃ and stir for 30 minutes. Then add the remaining deionized water, modified silica-1, and polyurethane-acrylic hybrid emulsion-1 and stir at 70℃ for 1 hour. Finally, add nano boehmite, PEG-1000, thickener, leveling agent, defoamer, expanding agent, N-methyldiethanolamine, mildew inhibitor, and 25wt% ammonia water and stir at room temperature for 2 hours to obtain the water-based coating.

[0064] Example 4

[0065] A water-based coating for dye-based PP synthetic photographic paper that enhances the adhesion of heat-mounted films and its preparation method are disclosed. The specific implementation method is the same as in Example 1, except that modified silica-1 is replaced with modified silica-2 in equal amounts.

[0066] Example 5

[0067] A water-based coating for dye-ink-specific PP synthetic photographic paper that enhances the adhesion of heat-mounted films and its preparation method are described. The specific implementation method is the same as in Example 1, except that modified silica-1 is replaced with modified silica-3 in equal amounts.

[0068] Example 6

[0069] A water-based coating for dye-based PP synthetic photographic paper that enhances the adhesion of heat-mounted films and its preparation method are disclosed. The specific implementation method is the same as in Example 1, except that polyurethane-acrylic hybrid emulsion-1 is replaced with an equal amount of polyurethane-acrylic hybrid emulsion-2.

[0070] Example 7

[0071] A water-based coating for dye-based PP synthetic photographic paper that enhances the adhesion of heat-mounted films and its preparation method are disclosed. The specific implementation method is the same as in Example 1, except that polyurethane-acrylic hybrid emulsion-1 is replaced with an equal amount of polyurethane-acrylic hybrid emulsion-3.

[0072] Example 8

[0073] A water-based coating for dye-based PP synthetic photographic paper that enhances the adhesion of heat-mounted films and its preparation method are disclosed. The specific implementation method is the same as in Example 1, except that polyurethane-acrylic hybrid emulsion-1 is replaced with an equal amount of polyurethane-acrylic hybrid emulsion-4.

[0074] Example 9

[0075] A water-based coating for dye-based PP synthetic photographic paper that enhances the adhesion of heat-mounted films and its preparation method are disclosed. The specific implementation method is the same as in Example 1, except that polyurethane-acrylic hybrid emulsion-1 is replaced with an equal amount of polyurethane-acrylic hybrid emulsion-5.

[0076] Example 10

[0077] A water-based coating for dye-based PP synthetic photographic paper that enhances the heat-mounting adhesion of lamination and inks, and its preparation method, are described in the same manner as in Example 1, except that the preparation method includes the following steps:

[0078] Add half the mass of PVA1799 to deionized water, heat to 95℃ and stir for 45 min. Then add the remaining deionized water, modified silica-1, and polyurethane-acrylic hybrid emulsion-1 and stir at 65℃ for 1.5 h. Finally, add nano boehmite, PEG-1000, thickener, leveling agent, defoamer, expanding agent, N-methyldiethanolamine, mildew inhibitor, and 25wt% ammonia water and stir at room temperature for 1.5 h to obtain water-based coating.

[0079] Comparative Example 1

[0080] A water-based coating for dye-based PP synthetic photographic paper that enhances the heat-mounting adhesion of the film and its preparation method are disclosed. The specific implementation method is the same as in Example 1, except that modified silica-1 is replaced in equal amounts with silica with an average particle size of 10 μm.

[0081] Performance testing

[0082] The following tests were conducted on the water-based coatings for dye-based PP synthetic photographic paper with improved heat-lamination adhesion obtained in the above embodiments and comparative examples:

[0083] 1. Ink absorption and clarity: The surface of untreated PP synthetic photographic paper was coated with the water-based coating prepared in this invention, with a coating amount of 32 g / m². 2 After drying, processed PP synthetic photographic paper is obtained. The ink absorption is tested according to the specification

[0078] of patent CN107674457B. Then, a 10-29x magnifying glass is used to observe the black lines of 2 pixels to see if there is ink bleeding and burrs, and to test the clarity.

[0084] 2. Coating adhesion: The surface of untreated PP synthetic photographic paper is coated with the water-based coating prepared in this invention, with a coating amount of 32 g / m². 2 After drying, processed PP synthetic photographic paper is obtained. Then, photos are printed with standard K&N ink. After corona treatment, the photos are thermally laminated using a laminating machine. Afterward, the paper is vigorously rubbed, and the time it takes for the film surface to peel and turn white is observed and recorded.

[0085] The test results are shown in Table 1:

[0086] Table 1

[0087]

[0088] As shown in Table 1, the water-based coating inks obtained in Examples 1-3 of this invention exhibit good absorbency, high film adhesion, and high printing clarity. A comparison between Example 4 and Example 1 shows that changing the ratio of 1-amino-5-hexen-2-ol to silica may clog the pores of silica, reducing its absorbency of additives in the ink and consequently decreasing ink absorption, film adhesion, and clarity. A comparison between Example 5 and Example 1 shows that excessively small silica particle size leads to a decrease in all properties. A comparison between Example 1 and Example 6 shows that changing the ratio of pentaerythritol triacrylate to N-vinylimidazole may cause imidazole ring accumulation, resulting in excessively strong interaction with the ink and decreased clarity. A comparison between Example 7 and Example 1... As can be seen, changing the ratio of polyether polyol and polymer may lead to excessive cross-linking, making the ink difficult to absorb, and reducing the ink's absorbency, coating strength, and clarity. A comparison between Example 8 and Example 1 shows that replacing pentaerythritol triacrylate with methyl methacrylate in equal amounts may lead to changes in cross-linking, causing the ink's additives to easily migrate to the surface, resulting in decreased coating strength. A comparison between Example 9 and Example 1 shows that without the addition of polymer to the polyurethane-acrylic hybrid emulsion, both coating strength and clarity decrease. A comparison between Example 10 and Example 1 shows that changing the degree of hydrolysis of polyvinyl alcohol reduces both the ink's absorbency and coating strength. A comparison between Comparative Example 1 and Example 1 shows that directly using silica reduces all performance characteristics.

[0089] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A water-based coating for dye-based ink-specific PP synthetic photographic paper that enhances the adhesion of heat-laminating films, characterized in that, Based on a 100% mass percentage, it contains the following components: 10-20% modified silica, 25-35% polyvinyl alcohol, 8-15% polyurethane-acrylic hybrid emulsion, 2.5-3.5% nano-boehmite, 1.5-2.5% dispersant, 0.5-0.7% thickener, 0.2-0.4% leveling agent, 0.3-0.5% defoamer, 2-4% expanding agent, 0.5-1.5% accelerator, 0.1-0.3% mildew inhibitor, 0.1-0.3% ammonia, and the balance being deionized water; The method for preparing the modified silica includes the following steps: Add silica and silane coupling agent to methanol solution, stir at room temperature for 40-50 min, then add 1-amino-5-hexen-2-ol, adjust pH to 10-12, react at 60-70℃ for 8-9 h to obtain modified silica. The preparation method of the polyurethane-acrylic hybrid emulsion includes the following steps: (1) Add pentaerythritol triacrylate, N-vinylimidazolium and initiator to methanol, react at 65-75℃ for 1-2 h, filter, wash and dry to obtain polymer; (2) Add polyether polyol, polyisocyanate, chain extender and catalyst to the reaction vessel and react at 75-85℃ for 4-6h to obtain prepolymer. Then cool down to 55-65℃, add polymer obtained in step (1), continue to cool down to 35-45℃, add neutralizer, react for 5-15min, add deionized water and stir, then add initiator, emulsifier and acrylic acid and react at 65-75℃ for 2-3h to obtain polyurethane-acrylic hybrid emulsion.

2. The water-based coating for dye-based ink-specific PP synthetic photographic paper to enhance heat lamination adhesion as described in claim 1, characterized in that, The silica has a particle size of 5-12 μm.

3. The water-based coating for dye-based ink-specific PP synthetic photographic paper to enhance heat lamination adhesion as described in claim 1, characterized in that, The mass ratio of silicon dioxide to 1-amino-5-hexen-2-ol is 1:(0.08-0.15).

4. The water-based coating for dye-based ink-specific PP synthetic photographic paper to enhance heat lamination adhesion as described in claim 1, characterized in that, The mass ratio of pentaerythritol triacrylate to N-vinylimidazole is 1:(0.16-0.3).

5. The water-based coating for dye-based ink-specific PP synthetic photographic paper to enhance heat lamination adhesion as described in claim 1, characterized in that, The mass ratio of the polyether polyol and the polymer in step (2) is 1:(0.07-0.13).

6. The water-based coating for dye-based ink-specific PP synthetic photographic paper to enhance heat lamination adhesion as described in claim 1, characterized in that, The nanoboehmite has a particle size of 5-15 nm.

7. The water-based coating for dye-based ink-specific PP synthetic photographic paper to enhance heat lamination adhesion as described in claim 1, characterized in that, The degree of alcoholysis of the polyvinyl alcohol is 87-89 mol.

8. A method for preparing a water-based coating for dye-based ink-specific PP synthetic photographic paper with improved heat-lamination film adhesion as described in any one of claims 1-7, characterized in that, Includes the following steps: Polyvinyl alcohol is added to a portion of deionized water, heated to 40-50℃ and stirred for 30-60 minutes. Then, the remaining deionized water, modified silica, and polyurethane-acrylic hybrid emulsion are added and stirred at 60-70℃ for 1-2 hours. Finally, nano-boehmite, dispersant, thickener, leveling agent, defoamer, expanding agent, accelerator, mildew inhibitor, and ammonia are added and stirred at room temperature for 1-2 hours to obtain a water-based coating.

Images