A low water vapor transmission rate coating for packaging material and a method for preparing the same

Abstract

This invention relates to the field of packaging materials technology, and more particularly to a low water vapor transmission rate coating for packaging materials and its preparation method. The aforementioned low water vapor transmission rate coating for packaging materials comprises, by mass percentage: 25-40% modified polyurethane resin, 5-20% linear alkane compound, 3-15% hydrophobic modified acrylic resin, 1-5% amino-terminated polyamide amine, 1-5% silica microparticles, 3-5% hydroxyethyl cellulose, 0.1-0.5% amino curing agent, 1-3% water-based additives, and the balance being water. The coating formed by this invention has an ultra-low water vapor transmission rate and also possesses heat-sealing capabilities. It eliminates the need for additional adhesive, lamination, or coating processes, simplifying the processing. The resulting coating is transparent, with a surface dyne value >42, and does not affect the appearance of paper or subsequent printing processes.

Description

Technical Field

[0001] This invention relates to the field of packaging materials technology, and in particular to a low water vapor permeability coating for packaging materials and its preparation method. Background Technology

[0002] In the field of packaging materials, coating technology is essential for industries with stringent barrier requirements, such as food, pharmaceuticals, and tobacco packaging materials.

[0003] Currently, packaging materials often employ metal plating (such as aluminum) or organic polymer coatings to achieve the function of blocking moisture and gas. However, these traditional methods have significant drawbacks. Taking aluminized inner liner paper as an example, although it forms a metal layer through physical vapor deposition and can effectively reduce water vapor permeability to approximately 30 g / (m³), its limitations remain. 2 •d) However, the material differences between the metal and the substrate make recycling and degradation difficult, which goes against environmental protection trends. At the same time, these coatings lack self-cleaning capabilities and are easily adhered to by environmental pollutants, affecting the appearance and hygiene of the packaging. More seriously, under high-temperature processing or storage conditions, the coating is prone to peeling or performance degradation, exhibiting poor high-temperature resistance, which limits its application in heat-sealing processes.

[0004] While polymer coatings can partially address the issue of material uniformity, traditional acrylic or polyurethane resins lack sufficient moisture barrier properties to meet ultra-low transmittance standards. Furthermore, the high surface energy of the coatings makes self-cleaning difficult, leading to the accumulation of dust and oil, which reduces the practicality and aesthetics of the packaging. Insufficient high-temperature resistance further exacerbates the problem; for example, during high-temperature sterilization or heat sealing, the coating may soften or decompose, causing barrier failure. These defects not only affect product shelf life but also increase production complexity, requiring additional processes such as lamination or coating to compensate for functional deficiencies.

[0005] Currently, how to develop coatings that combine ultra-low water vapor permeability, self-cleaning ability, and excellent high-temperature resistance to promote the sustainable development of the packaging materials industry and reduce dependence on traditional non-degradable materials has become an urgent technical problem to be solved. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by proposing a low water vapor permeability coating for packaging materials and its preparation method.

[0007] A low water vapor permeability coating for packaging materials comprises, by weight percentage: 25-40% modified polyurethane resin, 5-20% linear alkane compound, 3-15% hydrophobic modified acrylic resin, 1-5% amino-terminated polyamide amine, 1-5% silica microparticles, 3-5% hydroxyethyl cellulose, 0.1-0.5% amino curing agent, 1-3% water-based additives, and the balance being water.

[0008] This invention relates to a low water vapor transmission rate coating for packaging materials. The coating architecture consists of modified polyurethane resin, linear alkane compounds, hydrophobically modified acrylic resin, and amino-terminated polyamide amine. This provides excellent water-blocking performance while also exhibiting good film-forming ability. The hydrophobically modified acrylic resin, amino-terminated polyamide amine, and silica microparticles form a stable micro-nano composite rough structure, significantly increasing the water contact angle and enhancing hydrophobicity. This results in not only excellent waterproof performance but also superior stain and dirt resistance. The addition of hydroxyethyl cellulose (HFC) fills resin voids and allows the resin to encapsulate and aggregate around HFC, further increasing its density and significantly reducing the water vapor transmission rate of the original system. The addition of an amino curing agent lowers the film-forming and curing temperature of the coating, improving the surface condition after baking. This allows the coating to be dried and wound within the recommended board temperature range, preventing paper deformation and warping during coating and winding.

[0009] Preferably, the aqueous additives include at least one of ethanol, ethylene glycol, butyl ether, and isopropanol.

[0010] Preferably, the straight-chain alkane compound includes: oxidized polyethylene straight-chain alkane compound and / or aqueous polypropylene straight-chain alkane compound.

[0011] Preferably, the modified polyurethane resin has a particle size of 50-300 nm and a molecular weight of 150,000-200,000, and is a low-temperature baking film-forming resin.

[0012] Preferably, the modified polyurethane resin includes at least one of silicone-modified polyurethane, epoxy-modified polyurethane, and polycarbonate-modified polyurethane.

[0013] Preferably, the hydrophobically modified acrylic resin is prepared by the following steps: adding methyl methacrylate, butyl acrylate, methacrylic acid, acrylate-terminated siloxane, and vinyltriethoxysilane to water and stirring for 10-30 minutes, adding emulsifier and continuing to stir for 1-2 hours, adding initiator, and stirring at 70-80°C for 2-6 hours.

[0014] More preferably, the emulsifier is nonylphenol polyoxyethylene ether ammonium sulfate.

[0015] More preferably, the initiator is ammonium persulfate.

[0016] More preferably, the mass ratio of methyl methacrylate, butyl acrylate, methacrylic acid, acrylate-terminated siloxane, vinyltriethoxysilane, emulsifier, and initiator is 5-15:1-5:1-2:1-2:0.1-1:1-2:0.1-1.

[0017] Preferably, the silica microparticles are composed of silica microparticles with a particle size ≤100nm and silica microparticles with a particle size of 1-50μm, and the mass ratio of silica microparticles with a particle size ≤100nm to silica microparticles with a particle size of 1-50μm is 50-70:30-50.

[0018] Preferably, the silica microparticles are prepared by the following steps: nano silica, methyltriethoxysilane, and saturated ammonia are added to anhydrous ethanol and stirred for 5-15 hours, then filtered, washed, and vacuum dried.

[0019] More preferably, the mass ratio of nano-silica, methyltriethoxysilane, and saturated ammonia is 5-15:1-5:1-2.

[0020] Preferably, the amino-terminated polyamide amine (PAMAM) has an ethylenediamine core and a generation number of 2.0-4.0.

[0021] The preparation method of the above-mentioned low water vapor transmission rate coating for packaging materials includes the following steps:

[0022] (1) Hydroxyethyl cellulose was added to water and stirred to obtain mother liquor A;

[0023] (2) Add the modified polyurethane resin to mother liquor A and stir to obtain mother liquor B;

[0024] (3) Add terminal amino polyamide amine to hydrophobic modified acrylic resin and stir for 1-2 hours. Add silica microparticles and water and mix and grind for 1-2 hours to obtain masterbatch C.

[0025] (4) Add the straight-chain alkane compound, water-based additive and amino curing agent to the mother liquor B in sequence and stir. Add the masterbatch C and continue stirring.

[0026] Preferably, in step (1), the stirring speed is 250-300 r / min and the stirring time is 5-10 min.

[0027] Preferably, in step (2), the stirring speed is 300-350 r / min and the stirring time is 10-15 min.

[0028] Preferably, in step (3), the stirring speed is 100-400 r / min and the stirring time is 1-2 h.

[0029] Preferably, in step (3), the grinding speed is 500-700 r / min and the grinding time is 1-2 h.

[0030] Preferably, in step (4), the stirring speed is 300-350 r / min and the stirring time is 10-20 min.

[0031] The application method of the above-mentioned low water vapor transmission rate coating for packaging materials includes the following steps: applying the above-mentioned low water vapor transmission rate coating for packaging materials to the surface of the inner lining paper, with a coating amount ≥30g / m². 2 The coating is formed by drying.

[0032] Preferably, the coating method is roller coating, which is reverse coating.

[0033] Preferably, the drying temperature is 60-90℃ and the drying time is 15-30s.

[0034] Beneficial effects:

[0035] (1) The coating formed by the coating of the present invention has an ultra-low water vapor transmission rate. When the water vapor transmission rate is tested using methods such as GB / T 1037-2021, ISO-15106-2, or DIN 53122-1, the water vapor transmission rate value can be as low as 10 g / (m 2 •d) below, and far lower than the 30g / (m) of conventional aluminized inner lining paper. 2 •d) Water vapor transmission rate value, the coating is used for the inner liner paper, adheres tightly to the inner liner paper, and has excellent winding performance;

[0036] (2) The coating of the present invention ensures the water resistance of the substrate, as well as the uniformity and degradability of the substrate material. It does not contain halogen or metal components. During the recycling and degradation process after the packaging material is used, there is no problem of material inhomogeneity. It can be recycled, degraded, composted and other environmentally friendly treatments. The coating of the present invention can replace conventional non-degradable PVDC coating and aluminized inner lining paper when used for packaging inner lining paper.

[0037] (3) The hydrophobic modified acrylic resin used in this invention can effectively provide low surface energy. The siloxane groups on its molecular chain and the silanol groups on the surface of silica particles form a strong covalent network through the bridging effect of the terminal amino polyamide amine. This not only effectively fixes the silica particles in the matrix and forms a stable micro-nano composite rough structure, but also greatly increases the water contact angle and enhances the hydrophobic properties. It not only has excellent waterproof performance, but also prevents pollutants from effectively adhering to its surface, resulting in excellent anti-fouling and anti-staining effects. At the same time, while having ultra-low water vapor permeability, the dense cross-linked network significantly improves the thermal stability of the coating and gives it excellent high temperature resistance.

[0038] (4) The coating formed by the present invention has a heat-sealing function. In the process of forming the inner liner paper of the packaging, no additional glue, coating or lamination process is required, and the processing technology is simpler. The coating equipment used is ordinary coating equipment, which does not require large equipment such as vacuum metallization machine used in conventional metallization, and the production control process is simpler. At the same time, the production input cost is also lower. The coating formed by the present invention is a water-based transparent coating. After coating, the surface dyne value is >42, which does not affect the appearance of the paper and subsequent printing and other processes. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the structure of the inner lining paper obtained after coating with the coating obtained in this application. Wherein: 1, coating layer; 2, paper base.

[0040] Figure 2 The diagram shows a comparison of the water contact angle and water vapor transmission rate of the lining paper after coating treatment with the coatings obtained in Examples 1-7 and Comparative Examples 1-2.

[0041] Figure 3 The graph shows a comparison of the static water contact angle change rate of the inner lining paper after heat treatment, obtained by coating with the coatings obtained in Examples 1-7 and Comparative Examples 1-2. Detailed Implementation

[0042] The present invention will be further explained below with reference to specific embodiments.

[0043] The modified polyurethane resin used below is a silicone-modified polyurethane, purchased from a certain company (Jining) Chemical Technology Co., Ltd., with a solid content of 30±1% (the amount of modified polyurethane resin used below is based on the effective solid content), MFT=10℃. The straight-chain alkane compound used below is from BYKAQUACER535, sourced from BYK (Germany). The terminal amino-terminated polyamide amine (PAMAM) used below is from Xi'an Mouxi Biotechnology Co., Ltd., with ethylenediamine as the core and a generation number of 2.0. The hydroxyethyl cellulose used below is produced by Shandong Mousuo Chemical Technology Co., Ltd., with an aqueous solution solid content of 30-35%. The amino curing agent used below is Cytec 303, a water-oil dual-purpose curing agent produced by Zhanxin (China). The nonylphenol polyoxyethylene ether ammonium sulfate used below is from Nantong Mouruiyang Chemical Co., Ltd. The water-based additive used below is ethanol, a commercially available chemically pure reagent. The water used below is deionized water. The silicone-modified acrylic resin used below was produced by Zongyang Moujin Pigment Co., Ltd., with a molecular weight of 120,000-150,000 and Tg < -10℃.

[0044] Example 1

[0045] A low water vapor permeability coating for packaging materials comprises the following raw materials by mass percentage: 35% modified polyurethane resin, 15% linear alkane compound, 9% hydrophobic modified acrylic resin, 3% amino-terminated polyamide amine, 3% silica microparticles, 4% hydroxyethyl cellulose, 0.3% amino curing agent, 2% water-based additives, and the balance being deionized water.

[0046] The hydrophobically modified acrylic resin was prepared by the following steps: 10g of methyl methacrylate, 3g of butyl acrylate, 1.5g of methacrylic acid, 1.5g of acrylate-terminated siloxane, and 0.5g of vinyltriethoxysilane were added to 45g of deionized water and stirred at 250r / min for 20min. Then, 1.5g of nonylphenol polyoxyethylene ether ammonium sulfate was added and stirring was continued for 90min. Finally, 0.5g of ammonium persulfate was added and the mixture was stirred at 75℃ for 4h.

[0047] Silica microparticles are prepared by the following steps: 10g of silica particles, 3g of methyltriethoxysilane, and 1.5g of saturated ammonia are added to 40g of anhydrous ethanol and stirred at 500r / min for 10h. The mixture is then filtered, washed, and vacuum dried.

[0048] The preparation method of the above-mentioned low water vapor transmission rate coating for packaging materials includes the following steps:

[0049] (1) Add hydroxyethyl cellulose to deionized water and stir for 10 min at a stirring speed of 300 r / min to obtain mother liquor A;

[0050] (2) Add the modified polyurethane resin to the mother liquor A and stir for 15 minutes at a stirring speed of 350 r / min to obtain mother liquor B;

[0051] (3) Add amino-terminated polyamide amine to the hydrophobic modified acrylic resin and stir for 2 hours at a stirring speed of 400 r / min; add silica microparticles and deionized water and mix and grind for 2 hours at a grinding speed of 700 r / min to obtain masterbatch C;

[0052] (4) Add the straight-chain alkane compound, water-based additive and amino curing agent to the mother liquor B in sequence and stir for 15 min at a stirring speed of 350 r / min; add the masterbatch C and continue stirring for 20 min.

[0053] Comparative Example 1

[0054] A low water vapor permeability coating for packaging materials comprises, by weight percentage: 35% modified polyurethane resin, 15% linear alkane compound, 15% organosilicon modified acrylic resin, 4% hydroxyethyl cellulose, 0.3% amino curing agent, 2% water-based additives, and the balance being deionized water.

[0055] The preparation method of the above-mentioned low water vapor transmission rate coating for packaging materials includes the following steps:

[0056] (1) Add hydroxyethyl cellulose to deionized water and stir for 10 min at a stirring speed of 300 r / min to obtain mother liquor A;

[0057] (2) Add the modified polyurethane resin to the mother liquor A and stir for 15 minutes at a stirring speed of 350 r / min to obtain mother liquor B;

[0058] (3) Add the silicone-modified acrylic resin, straight-chain alkane compound, water-based additive and amino curing agent to the mother liquor B in sequence and stir for 15 min at a stirring speed of 350 r / min.

[0059] Comparative Example 2

[0060] A low water vapor permeability coating for packaging materials comprises, by weight percentage: 35% modified polyurethane resin, 15% linear alkane compound, 15% organosilicon modified acrylic resin, 0.3% amino curing agent, 2% water-based additives, and the balance being deionized water.

[0061] The preparation method of the above-mentioned low water vapor transmission rate coating for packaging materials includes the following steps:

[0062] (1) Add the modified polyurethane resin to deionized water and stir for 15 min at a stirring speed of 350 r / min to obtain mother liquor B;

[0063] (2) Add the silicone-modified acrylic resin, straight-chain alkane compound, water-based additive and amino curing agent to the mother liquor B in sequence and stir for 15 min at a stirring speed of 350 r / min.

[0064] Comparative Example 3

[0065] A low water vapor permeability coating for packaging materials comprises, by weight percentage: 35% modified polyurethane resin, 15% linear alkane compound, 15% organosilicon modified acrylic resin, 4% hydroxyethyl cellulose, 2% water-based additives, and the balance being deionized water.

[0066] The preparation method of the above-mentioned low water vapor transmission rate coating for packaging materials includes the following steps:

[0067] (1) Add hydroxyethyl cellulose to deionized water and stir for 10 min at a stirring speed of 300 r / min to obtain mother liquor A;

[0068] (2) Add the modified polyurethane resin to the mother liquor A and stir for 15 minutes at a stirring speed of 350 r / min to obtain mother liquor B;

[0069] (3) Add the silicone-modified acrylic resin, straight-chain alkane compound and water-based additive to the mother liquor B in sequence and stir for 15 minutes at a stirring speed of 350 r / min.

[0070] Comparative Example 4

[0071] A low water vapor permeability coating for packaging materials comprises, by weight percentage: 45% modified polyurethane resin, 15% linear alkane compound, 15% organosilicon modified acrylic resin, 4% hydroxyethyl cellulose, 0.3% amino curing agent, 2% water-based additives, and the balance being deionized water.

[0072] The preparation method of the above-mentioned low water vapor transmission rate coating for packaging materials includes the following steps:

[0073] (1) Add hydroxyethyl cellulose to deionized water and stir for 10 min at a stirring speed of 300 r / min to obtain mother liquor A;

[0074] (2) Add the modified polyurethane resin to the mother liquor A and stir for 15 minutes at a stirring speed of 350 r / min to obtain mother liquor B;

[0075] (3) Add the silicone-modified acrylic resin, straight-chain alkane compound, water-based additive and amino curing agent to the mother liquor B in sequence and stir for 15 min at a stirring speed of 350 r / min.

[0076] Example 2

[0077] A low water vapor permeability coating for packaging materials comprises the following raw materials by mass percentage: 35% modified polyurethane resin, 8% linear alkane compound, 9% hydrophobic modified acrylic resin, 2% amino-terminated polyamide amine, 4% silica microparticles, 4% hydroxyethyl cellulose, 0.3% amino curing agent, 2% water-based additives, and the balance being deionized water.

[0078] The hydrophobically modified acrylic resin was prepared by the following steps: 10g of methyl methacrylate, 3g of butyl acrylate, 1.5g of methacrylic acid, 1.5g of acrylate-terminated siloxane, and 0.5g of vinyltriethoxysilane were added to 45g of deionized water and stirred at 250r / min for 20min. Then, 1.5g of nonylphenol polyoxyethylene ether ammonium sulfate was added and stirring was continued for 90min. Finally, 0.5g of ammonium persulfate was added and the mixture was stirred at 75℃ for 4h.

[0079] Silica microparticles are prepared by the following steps: 10g of silica particles, 3g of methyltriethoxysilane, and 1.5g of saturated ammonia are added to 40g of anhydrous ethanol and stirred at 500r / min for 10h. The mixture is then filtered, washed, and vacuum dried.

[0080] The preparation method of the above-mentioned low water vapor transmission rate coating for packaging materials includes the following steps:

[0081] (1) Add hydroxyethyl cellulose to deionized water and stir for 10 min at a stirring speed of 300 r / min to obtain mother liquor A;

[0082] (2) Add the modified polyurethane resin to the mother liquor A and stir for 15 minutes at a stirring speed of 350 r / min to obtain mother liquor B;

[0083] (3) Add amino-terminated polyamide amine to the hydrophobic modified acrylic resin and stir for 2 hours at a stirring speed of 400 r / min; add silica microparticles and deionized water and mix and grind for 2 hours at a grinding speed of 700 r / min to obtain masterbatch C;

[0084] (4) Add the straight-chain alkane compound, water-based additive and amino curing agent to the mother liquor B in sequence and stir for 15 min at a stirring speed of 350 r / min; add the masterbatch C and continue stirring for 20 min.

[0085] Example 3

[0086] A low water vapor permeability coating for packaging materials comprises, by weight percentage: 35% modified polyurethane resin, 20% linear alkane compound, 3% hydrophobic modified acrylic resin, 1% amino-terminated polyamide amine, 1% silica microparticles, 4% hydroxyethyl cellulose, 0.3% amino curing agent, 2% water-based additives, and the balance being deionized water.

[0087] The hydrophobically modified acrylic resin was prepared by the following steps: 7g of methyl methacrylate, 4g of butyl acrylate, 1.2g of methacrylic acid, 1.8g of acrylate-terminated siloxane, and 0.2g of vinyltriethoxysilane were added to 48g of deionized water and stirred at 200r / min for 25min. Then, 1.2g of nonylphenol polyoxyethylene ether ammonium sulfate was added and stirring was continued for 110min. Finally, 0.2g of ammonium persulfate was added and the mixture was stirred at 77℃ for 2.5h.

[0088] Silica microparticles are prepared by the following steps: 12g of silica particles, 2g of methyltriethoxysilane, and 1.8g of saturated ammonia are added to 35g of anhydrous ethanol and stirred at 550r / min for 7h. The mixture is then filtered, washed, and vacuum dried.

[0089] The preparation method of the above-mentioned low water vapor transmission rate coating for packaging materials includes the following steps:

[0090] (1) Add hydroxyethyl cellulose to deionized water and stir for 10 min at a stirring speed of 300 r / min to obtain mother liquor A;

[0091] (2) Add the modified polyurethane resin to the mother liquor A and stir for 15 minutes at a stirring speed of 350 r / min to obtain mother liquor B;

[0092] (3) Add amino-terminated polyamide amine to the hydrophobic modified acrylic resin and stir for 2 hours at a stirring speed of 400 r / min; add silica microparticles and deionized water and mix and grind for 2 hours at a grinding speed of 700 r / min to obtain masterbatch C;

[0093] (4) Add the straight-chain alkane compound, water-based additive and amino curing agent to the mother liquor B in sequence and stir for 15 min at a stirring speed of 350 r / min; add the masterbatch C and continue stirring for 20 min.

[0094] Example 4

[0095] A low water vapor permeability coating for packaging materials comprises the following raw materials by mass percentage: 35% modified polyurethane resin, 5% linear alkane compound, 9% hydrophobic modified acrylic resin, 3% amino-terminated polyamide amine, 3% silica microparticles, 4% hydroxyethyl cellulose, 0.3% amino curing agent, 2% water-based additives, and the balance being deionized water.

[0096] The hydrophobically modified acrylic resin was prepared by the following steps: 13g of methyl methacrylate, 2g of butyl acrylate, 1.8g of methacrylic acid, 1.2g of acrylate-terminated siloxane, and 0.8g of vinyltriethoxysilane were added to 42g of deionized water and stirred at 300r / min for 15min. Then, 1.8g of nonylphenol polyoxyethylene ether ammonium sulfate was added and stirring was continued for 70min. Finally, 0.8g of ammonium persulfate was added and the mixture was stirred at 73℃ for 5.5h.

[0097] Silica microparticles are prepared by the following steps: 8g of silica particles, 4g of methyltriethoxysilane, and 1.2g of saturated ammonia are added to 45g of anhydrous ethanol and stirred at 450r / min for 13h. The mixture is then filtered, washed, and vacuum dried.

[0098] The preparation method of the above-mentioned low water vapor transmission rate coating for packaging materials includes the following steps:

[0099] (1) Add hydroxyethyl cellulose to deionized water and stir for 10 min at a stirring speed of 300 r / min to obtain mother liquor A;

[0100] (2) Add the modified polyurethane resin to the mother liquor A and stir for 15 minutes at a stirring speed of 350 r / min to obtain mother liquor B;

[0101] (3) Add amino-terminated polyamide amine to the hydrophobic modified acrylic resin and stir for 2 hours at a stirring speed of 400 r / min; add silica microparticles and deionized water and mix and grind for 2 hours at a grinding speed of 700 r / min to obtain masterbatch C;

[0102] (4) Add the straight-chain alkane compound, water-based additive and amino curing agent to the mother liquor B in sequence and stir for 15 min at a stirring speed of 350 r / min; add the masterbatch C and continue stirring for 20 min.

[0103] Example 5

[0104] A low water vapor permeability coating for packaging materials comprises the following raw materials by mass percentage: 25% modified polyurethane resin, 15% linear alkane compound, 9% hydrophobic modified acrylic resin, 3% amino-terminated polyamide amine, 3% silica microparticles, 4% hydroxyethyl cellulose, 0.3% amino curing agent, 2% water-based additives, and the balance being deionized water.

[0105] The hydrophobically modified acrylic resin was prepared by the following steps: 8g of methyl methacrylate, 3.5g of butyl acrylate, 1.4g of methacrylic acid, 1.6g of acrylate-terminated siloxane, and 0.3g of vinyltriethoxysilane were added to 46g of deionized water and stirred at 220r / min for 22min. Then, 1.3g of nonylphenol polyoxyethylene ether ammonium sulfate was added and stirring was continued for 100min. Finally, 0.4g of ammonium persulfate was added and the mixture was stirred at 76℃ for 3.5h.

[0106] Silica microparticles were prepared by the following steps: 11g of silica particles, 2.5g of methyltriethoxysilane, and 1.7g of saturated ammonia were added to 38g of anhydrous ethanol and stirred at 520r / min for 8h. The mixture was then filtered, washed, and vacuum dried.

[0107] The preparation method of the above-mentioned low water vapor transmission rate coating for packaging materials includes the following steps:

[0108] (1) Add hydroxyethyl cellulose to deionized water and stir for 10 min at a stirring speed of 300 r / min to obtain mother liquor A;

[0109] (2) Add the modified polyurethane resin to the mother liquor A and stir for 15 minutes at a stirring speed of 350 r / min to obtain mother liquor B;

[0110] (3) Add amino-terminated polyamide amine to the hydrophobic modified acrylic resin and stir for 2 hours at a stirring speed of 400 r / min; add silica microparticles and deionized water and mix and grind for 2 hours at a grinding speed of 700 r / min to obtain masterbatch C;

[0111] (4) Add the straight-chain alkane compound, water-based additive and amino curing agent to the mother liquor B in sequence and stir for 15 min at a stirring speed of 350 r / min; add the masterbatch C and continue stirring for 20 min.

[0112] Example 6

[0113] A low water vapor permeability coating for packaging materials comprises the following raw materials by mass percentage: 35% modified polyurethane resin, 15% linear alkane compound, 15% hydrophobic modified acrylic resin, 5% amino-terminated polyamide amine, 5% silica microparticles, 4% hydroxyethyl cellulose, 0.3% amino curing agent, 2% water-based additives, and the balance being deionized water.

[0114] The hydrophobically modified acrylic resin is prepared by the following steps: 15g of methyl methacrylate, 5g of butyl acrylate, 2g of methacrylic acid, 2g of acrylate-terminated siloxane, and 1g of vinyltriethoxysilane are added to 50g of deionized water and stirred at 400r / min for 30min. Then, 2g of nonylphenol polyoxyethylene ether ammonium sulfate is added and stirring is continued for 2h. Finally, 1g of ammonium persulfate is added and stirred at 80℃ for 6h.

[0115] Silica microparticles are prepared by the following steps: 15g of silica particles, 5g of methyltriethoxysilane, and 2g of saturated ammonia are added to 50g of anhydrous ethanol and stirred at 600r / min for 15h. The mixture is then filtered, washed, and vacuum dried.

[0116] The preparation method of the above-mentioned low water vapor transmission rate coating for packaging materials includes the following steps:

[0117] (1) Add hydroxyethyl cellulose to deionized water and stir for 10 min at a stirring speed of 300 r / min to obtain mother liquor A;

[0118] (2) Add the modified polyurethane resin to the mother liquor A and stir for 15 minutes at a stirring speed of 350 r / min to obtain mother liquor B;

[0119] (3) Add amino-terminated polyamide amine to the hydrophobic modified acrylic resin and stir for 2 hours at a stirring speed of 400 r / min; add silica microparticles and deionized water and mix and grind for 2 hours at a grinding speed of 700 r / min to obtain masterbatch C;

[0120] (4) Add the straight-chain alkane compound, water-based additive and amino curing agent to the mother liquor B in sequence and stir for 15 min at a stirring speed of 350 r / min; add the masterbatch C and continue stirring for 20 min.

[0121] Example 7

[0122] A low water vapor permeability coating for packaging materials comprises the following raw materials by mass percentage: 35% modified polyurethane resin, 15% linear alkane compound, 3% hydrophobic modified acrylic resin, 1% amino-terminated polyamide amine, 1% silica microparticles, 4% hydroxyethyl cellulose, 0.3% amino curing agent, 2% water-based additives, and the balance being deionized water.

[0123] The hydrophobically modified acrylic resin is prepared by the following steps: 5g of methyl methacrylate, 1g of butyl acrylate, 1g of methacrylic acid, 1g of acrylate-terminated siloxane, and 0.1g of vinyltriethoxysilane are added to 40g of deionized water and stirred at 100r / min for 10min. Then, 1g of nonylphenol polyoxyethylene ether ammonium sulfate is added and stirring is continued for 1h. Finally, 0.1g of ammonium persulfate is added and stirred at 70℃ for 2h.

[0124] Silica microparticles are prepared by the following steps: 5g of silica particles, 1g of methyltriethoxysilane, and 1g of saturated ammonia are added to 30g of anhydrous ethanol and stirred at 400r / min for 5h. The mixture is then filtered, washed, and vacuum dried.

[0125] The preparation method of the above-mentioned low water vapor transmission rate coating for packaging materials includes the following steps:

[0126] (1) Add hydroxyethyl cellulose to deionized water and stir for 10 min at a stirring speed of 300 r / min to obtain mother liquor A;

[0127] (2) Add the modified polyurethane resin to the mother liquor A and stir for 15 minutes at a stirring speed of 350 r / min to obtain mother liquor B;

[0128] (3) Add amino-terminated polyamide amine to the hydrophobic modified acrylic resin and stir for 2 hours at a stirring speed of 400 r / min; add silica microparticles and deionized water and mix and grind for 2 hours at a grinding speed of 700 r / min to obtain masterbatch C;

[0129] (4) Add the straight-chain alkane compound, water-based additive and amino curing agent to the mother liquor B in sequence and stir for 15 min at a stirring speed of 350 r / min; add the masterbatch C and continue stirring for 20 min.

[0130] Comparative tests were conducted using the coatings obtained in Examples 1-7 and Comparative Examples 1-4, as follows: Each group of coatings was applied in reverse to the surface of the inner lining paper (Hengfeng 70g ordinary inner lining paper, with a rough back side) using a roller coating method, with a wet film weight of 35g / m². 2 The coating is formed on the surface of the inner lining paper by drying at 85℃ for 15 seconds. The inner lining paper obtained after the above coating treatments is as follows: Figure 1As shown, a coating 1 (formed by coating each group of paints) is formed on the surface of the paper base 2 (i.e., the inner lining paper).

[0131] The reference example is 70g Hengfeng aluminized inner lining paper. The winding performance and surface appearance of each group are shown in Table 1.

[0132] Table 1. Winding performance and surface appearance of each group

[0133]

[0134] Since the inner lining paper obtained after coating treatment with the coatings obtained in Comparative Examples 3 and 4 was unqualified, only the inner lining paper obtained after coating treatment with the coatings obtained in Examples 1-7 and Comparative Examples 1-2 was used to further determine the water contact angle and water vapor transmission rate.

[0135] The static water contact angle of each group of inner lining paper was measured using a contact angle meter. The water vapor transmission rate of each group of inner lining paper was determined according to GB / T 1037-2021 "Determination of Water Vapor Transmission Performance of Plastic Films and Sheets - Cup Method for Weight Gain and Loss". The instrument used was a water vapor transmission rate tester manufactured by Guangzhou Biaoji. The test conditions were 38℃ × 90% humidity, with the coated area facing the high temperature and high humidity side.

[0136] like Figure 2 As shown, the lining paper treated with the coating obtained in Example 1 has the largest static water contact angle, which is slightly better than the reference example and Example 2 (the difference is not significant), and significantly better than the other groups. Moreover, the static water contact angle of the lining paper treated with the coating obtained in Examples 1-7 is significantly better than that of Comparative Examples 1-2. At the same time, the water vapor transmission rate of the lining paper treated with the coating obtained in Example 1 is the smallest, which is slightly better than that of Comparative Example 1 and Example 2 (the difference is not significant), and significantly better than the other groups.

[0137] Each group of inner lining paper was placed in a high-temperature environment of 100℃ for 6 hours. After being removed, the static water contact angle was measured again, and the change rate of static water contact angle was calculated to characterize the heat resistance of the coating.

[0138] Rate of change of static water contact angle = (original static water contact angle - static water contact angle after heat treatment) ÷ original static water contact angle × 100%.

[0139] like Figure 3 As shown, the static water contact angle change rate of the inner lining paper obtained after coating treatment with the coating obtained in Example 1 is the smallest, slightly better than Example 2 (the difference is not significant), and significantly better than the other groups.

[0140] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A low water vapor permeability coating for packaging materials, characterized in that, Its raw materials, by mass percentage, include: 25-35% modified polyurethane resin, 5-20% linear alkane compound, 3-15% hydrophobic modified acrylic resin, 1-5% amino-terminated polyamide amine, 1-5% silica microparticles, 4% hydroxyethyl cellulose, 0.3% amino curing agent, 2% water-based additives, and the balance being water. Straight-chain alkane compounds include: straight-chain alkane compounds of oxidized polyethylene and / or straight-chain alkane compounds of aqueous polypropylene; The silica microparticles are prepared by the following steps: nano silica, methyltriethoxysilane and saturated ammonia are added to anhydrous ethanol and stirred for 5-15 hours, then filtered, washed and vacuum dried. The hydrophobically modified acrylic resin is prepared by the following steps: methyl methacrylate, butyl acrylate, methacrylic acid, acrylate-terminated siloxane, and vinyltriethoxysilane are added to water and stirred for 10-30 minutes. An emulsifier is added and stirring is continued for 1-2 hours. An initiator is added and stirred at 70-80°C for 2-6 hours.

2. The low water vapor permeability coating for packaging materials according to claim 1, characterized in that, The aqueous additive is ethanol.

3. The low water vapor permeability coating for packaging materials according to claim 1, characterized in that, The modified polyurethane resin is an organosilicon-modified polyurethane.

4. The low water vapor permeability coating for packaging materials according to claim 1, characterized in that, The mass ratio of methyl methacrylate, butyl acrylate, methacrylic acid, acrylate-terminated siloxane, vinyltriethoxysilane, emulsifier, and initiator is 5-15:1-5:1-2:1-2:0.1-1:1-2:0.1-1.

5. A method for preparing a low water vapor transmission rate coating for packaging materials as described in any one of claims 1-4, characterized in that, Includes the following steps, (1) Hydroxyethyl cellulose was added to water and stirred to obtain mother liquor A; (2) Add the modified polyurethane resin to mother liquor A and stir to obtain mother liquor B; (3) Add terminal amino polyamide amine to hydrophobic modified acrylic resin and stir for 2 hours. Add silica microparticles and water and mix and grind for 2 hours to obtain masterbatch C. (4) Add the straight-chain alkane compound, water-based additive and amino curing agent to the mother liquor B in sequence and stir. Add the masterbatch C and continue stirring.

6. A method for applying a low water vapor transmission rate coating for packaging materials as described in any one of claims 1-4, characterized in that, Includes the following steps: The packaging material is coated onto the surface of the inner liner paper with a low water vapor permeability coating at a coating weight of 35 g / m². 2 The coating is formed by drying.

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