High-strength light-weight packaging carton and preparation method thereof

Abstract

The invention relates to the technical field of packaging cartons, and discloses a high-strength light-weight packaging carton and a preparation method thereof. The preparation method comprises the following steps: S1, uniformly mixing trihydroxy heptaoctyl poss, 3-bromopropylene, sodium carbonate and tetrahydrofuran, and reacting at 50-60 DEG C for 3-5 hours to obtain modified poss; s2, hexamethylol melamine, ethanol and modified poss are taken, and modified etherified amino resin is prepared; s3, uniformly mixing the modified etherified amino resin, sulfydryl modified silicon dioxide and a photoinitiator to obtain an additive; taking acrylic emulsion, epoxy / acrylic core-shell emulsion, hyperbranched polyurethane acrylate and an additive, uniformly stirring to obtain a reinforced coating, coating the surface of the light-weight packaging carton with the reinforced coating, and drying and curing to obtain the high-strength light-weight packaging carton.

Description

Technical Field

[0001] The invention relates to the technical field of packaging cartons and discloses a high-strength and lightweight packaging carton and a preparation method thereof. Background Art

[0002] With the rapid development of the logistics and commodity packaging industries, the demand for packaging cartons continues to increase, and the development direction of "low weight, high strength, and lightweight" has become a major trend. In the existing technology, the strength and water resistance of lightweight packaging cartons still need to be improved. When facing a humid environment or needing to withstand greater pressure, packaging cartons are prone to deformation, breakage and other problems. In order to improve the performance of cartons, surface coating technology has received widespread attention. By spraying a specific coating on the surface of the carton, it can not only effectively prevent water from entering, but also significantly increase the strength of the carton. However, the existing coating technology still has some shortcomings in practical applications. For example, the adhesion of the coating is weak, and it is easy to fall off or peel off during transportation, folding or long-term storage, affecting the overall strength and performance of the carton. In summary, it is of great significance to study a high-strength lightweight packaging carton with good waterproofness and strong adhesion on the surface coating and a preparation method thereof. Summary of the Invention

[0003] The object of the present invention is to provide a high-strength and lightweight packaging carton and a preparation method thereof, so as to solve the problems raised in the above-mentioned background technology.

[0004] In order to solve the above technical problems, the present invention provides the following technical solution: a method for preparing a high-strength lightweight packaging carton, comprising the following steps:

[0005] S1: Mix trihydroxy heptaoctyl poss, 3-bromopropylene, sodium carbonate and tetrahydrofuran evenly, and react at 50-60°C for 3-5h to obtain modified poss;

[0006] S2: Take the silica composition, add it to a mixed solution of water and ethanol, heat it to 50-60°C, stir it evenly, add 3-mercaptopropyltriethoxysilane, keep it warm and stir it for 4-6 hours, remove the solvent, and obtain mercapto-modified silica;

[0007] S3: Take hexamethylol melamine, ethanol, and modified poss, stir evenly, adjust the pH value to 3-4, heat to 40-55°C, stir evenly, keep warm and react for 1-2 hours, adjust the pH to 8-10, control the vacuum degree to 0.06-0.09 MPa, and react at 90-105°C under vacuum conditions for 2-4 hours to obtain modified etherified amino resin;

[0008] S4: Take modified etherified amino resin, mercapto-modified silica, and photoinitiator, mix them evenly to obtain additives; take acrylic emulsion, epoxy / acrylic core-shell emulsion, hyperbranched polyurethane acrylate, and additives, stir them evenly to obtain reinforced coating: apply the reinforced coating on the surface of a lightweight packaging carton, dry and cure it to obtain a high-strength lightweight packaging carton.

[0009] More optimally, the molar ratio of trihydroxy heptaoctyl poss, 3-bromopropylene, and sodium carbonate is 1: (1-1.2): (1-1.2); the amount of tetrahydrofuran added is 4-10 times the total mass of trihydroxy heptaoctyl poss, 3-bromopropylene, and sodium carbonate; the mercapto-modified silica includes the following raw materials, calculated by mass: 10-15 parts of silica composition, 1-1.5 parts of 3-mercaptopropyltriethoxysilane, 50-80 parts of a mixed solution of water and ethanol (the volume ratio of water to ethanol is 1 :1); the molar ratio of hexahydroxymethylmelamine, ethanol and modified poss is 1:(3-5):(2-4); the additives include the following raw materials, calculated in parts by mass: 3-4 parts of modified etherified amino resin, 2-4 parts of mercapto-modified silica, and 0.1-0.2 parts of photoinitiator; the enhanced coating includes the following raw materials, calculated in parts by mass: 15-25 parts of acrylic emulsion, 6-10 parts of epoxy / acrylic core-shell emulsion, 10-15 parts of hyperbranched polyurethane acrylate, and 5-9 parts of additives.

[0010] More optimally, the base paper used to prepare the lightweight carton has a gram weight of less than 100 g / m2.

[0011] More optimally, the silicon dioxide composition comprises 1-3 μm silicon dioxide and 10-20 nm silicon dioxide in a mass ratio of (1-2):1.

[0012] More optimally, the silicon dioxide composition comprises 1 μm silicon dioxide and 20 nm silicon dioxide in a mass ratio of 2:1.

[0013] More optimally, the preparation of the epoxy / acrylic core-shell emulsion comprises the following steps: Step 1: mixing epoxy resin, phthalic anhydride, and dimethylethylenediamine, heating to 130° C. for reaction, reacting until the acid value is less than 8 mg KOH / g, adding capric acid, cooling to 115-120° C., condensing and refluxing for 2-4 hours to obtain a modified epoxy resin;

[0014] Step 2: Evenly mix 2,2,3,3,3-pentafluoro-2-fluoropropyl acrylate, acrylic acid, methacrylic acid, octadecyl acrylate, and hydroquinone to obtain a monomer composition; take α-methylstyrene and benzoyl peroxide, dissolve them in propylene glycol methyl ether, heat to 70-80°C, dropwise add the monomer composition, heat to 80-90°C and react for 3-4 hours, add modified epoxy resin, stir evenly, react at 110°C for 1-2 hours, cool to 50-55°C, add triethylamine and stir for 30-60 minutes, remove the solvent, add water, and stir at high speed to obtain an epoxy / acrylic core-shell emulsion.

[0015] More optimally, the epoxy / acrylic core-shell emulsion includes the following raw materials, calculated by mass: 12 to 15 parts of epoxy resin, 2 to 3 parts of phthalic anhydride, 0.04 to 0.06 parts of dimethylethylenediamine, 3 to 4 parts of decanoic acid, 0.8 to 1.5 parts of 2,2,3,3,3-pentafluoro-2-fluoropropyl acrylate, 3 to 4 parts of acrylic acid, 2 to 3 parts of methacrylic acid, 0.4 to 0.6 parts of octadecyl acrylate, 0.01 to 0.02 parts of hydroquinone, 1 to 2 parts of α-methylstyrene, 0.3 to 0.5 parts of benzoyl peroxide, 4 to 5 parts of propylene glycol methyl ether, and 4 to 5 parts of triethylamine; the amount of water added is 1.5 to 2 times the mass of the monomer composition.

[0016] More optimally, the preparation of the hyperbranched polyurethane acrylate includes the following steps: adding polytetramethylene glycol-1000 to acetone and stirring evenly, heating to 70-80°C, adding isophorone diisocyanate and dibutyltin dilaurate, stirring and reacting for 2-3 hours to obtain an isocyanate-terminated prepolymer; adding a chain extender, reacting at 60-70°C for 2-3 hours, adding hydroxyethyl methacrylate dropwise and stirring and reacting until the content of isocyanate groups in the system reaches the theoretical end point, and removing acetone by rotary evaporation to obtain the hyperbranched polyurethane acrylate.

[0017] More optimally, the hyperbranched polyurethane acrylate includes the following raw materials, calculated by mass: 20 to 30 parts of polytetramethylene glycol, 20 to 30 parts of acetone, 15 to 20 parts of isophorone diisocyanate, 0.5 to 1 part of dibutyltin dilaurate, and 3 to 5 parts of a chain extender.

[0018] More optimally, the chain extender comprises octahydroxybutyl poss and 1,3-propylene glycol in a mass ratio of (2-3): (1-2).

[0019] More optimally, when the enhanced coating is applied to the surface of lightweight packaging cartons, the coating amount on one side is 15 to 25 g / m 2 The curing process is: ultraviolet irradiation for 20 to 30 minutes, drying at 100 to 120°C for 1 to 2 hours.

[0020] Compared with the prior art, the present invention has the following beneficial effects: a reinforcing coating is applied to the surface of a lightweight packaging carton, wherein the reinforcing coating comprises an acrylic emulsion, an epoxy / acrylic core-shell emulsion, a hyperbranched polyurethane acrylate, and an additive;

[0021] The acrylic emulsion uses Rosf's organic-inorganic composite special acrylic emulsion ROSF-5588, which has strong adhesion. The epoxy / acrylic core-shell emulsion combines the advantages of strong adhesion and good water resistance of epoxy resin and good film-forming property of acrylic resin, and adds fluorinated propyl acrylate and long-chain acrylate to further improve the waterproof performance of the coating. Hyperbranched polyurethane acrylate introduces the polyurethane structure to improve wear resistance, wherein the degree of branching is controlled by the addition ratio of octahydroxybutyl POSS and 1,3-propylene glycol. The addition of octahydroxybutyl POSS can increase the degree of branching and optimize the film-forming property. It also has a similar structure with the additive and improves the affinity between the two. However, the addition ratio should not be too high. Excessive addition leads to excessive branching, which reduces the compatibility of hyperbranched polyurethane acrylate with acrylic emulsion and epoxy / acrylic core-shell emulsion, and affects the performance. In summary, this scheme obtains a coating matrix by blending acrylic emulsion, epoxy / acrylic core-shell emulsion, and hyperbranched polyurethane acrylate and controlling the addition ratio to make them compatible, thereby obtaining a coating with strong adhesion and high strength.

[0022] The additives include modified etherified amino resin, mercapto-modified silica, and a photoinitiator; the modified etherified amino resin is obtained by reacting a hydroxyl-containing modified poss, ethanol, and hexahydroxymethyl melamine, and plays an auxiliary curing role in the coating; the modified poss contains a heptaoctyl group, which further improves the water resistance of the coating, and contains double bonds, which can participate in the cross-linking reaction in the subsequent step, thereby improving the compatibility of the additive with the above-mentioned coating matrix; the mercapto-modified silica is a silica composition modified by a mercaptosilane coupling agent, comprising 1 μm silica and 20 nm silica, with a particle size gradient, thereby improving dispersibility and strength; the amount of the mercapto-modified silica added also needs to be controlled. On the one hand, in order to reduce weight, the amount of inorganic filler added should not be too much. On the other hand, the mercapto group can cross-link with the double bonds in the modified etherified amino resin and hyperbranched polyurethane acrylate during ultraviolet light irradiation in the subsequent step, acting as a cross-linking agent, which can improve the compatibility between the two and increase the cross-linking degree to enhance strength. However, excessive addition leads to excessive cross-linking, which in turn leads to a decrease in performance. In summary, the additive prepared in this scheme can further improve the waterproofness, strength, and adhesion of the coating, and has good dispersibility. DETAILED DESCRIPTION

[0023] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0024] It should be noted that the purchasers of all raw materials involved in the present invention are not particularly restricted, and illustratively include: ethanol (CAS: 64-17-5); acrylic emulsion (ROSF-5588, Rosf); epoxy resin (E-20, Nanjing Bermuda Biotechnology); dimethylethylenediamine (CAS: 110-70-3); polytetramethylenediol-1000 (Shandong Suihua Biotechnology); octahydroxybutyl poss (3131, Xi'an Qiyue Biotechnology); 1,3-propylene glycol (CAS: 504-63-2); trihydroxyheptaoctyl poss (JH-P302, Shanghai Jiehua New Materials); sodium carbonate (anhydrous sodium carbonate); 1 μm silica, 20 nm silica (Zhejiang Manli Nanotechnology); hexahydroxymethylmelamine (CAS: 3089-11-0); photoinitiator (photoinitiator TPO, CAS: 75980-60-8);

[0025] Unless otherwise specified, the following are parts by mass and mass ratios;

[0026] Preparation of epoxy / acrylic core-shell emulsion: 14 parts of E-20 epoxy resin, 2.5 parts of phthalic anhydride, and 0.05 parts of dimethylethylenediamine were mixed, stirred, and slowly heated to 130°C for reaction. During the reaction, the acid value was detected. When the acid value was <8 mgKOH / g, 4 parts of decanoic acid were added, the temperature was lowered to 120°C, and condensed and refluxed for 4 hours to obtain a modified epoxy resin; 1 part of 2,2,3,3,3-pentafluoro-2-fluoropropyl acrylate, 3 parts of acrylic acid, 3 parts of methacrylic acid, and 0.5 parts of propylene glycol were mixed. 1 part of octadecyl acrylate and 0.01 part of hydroquinone are mixed to obtain a monomer composition; 1 part of α-methylstyrene and 0.4 part of benzoyl peroxide are dissolved in 5 parts of propylene glycol methyl ether, the temperature is raised to 70°C, the monomer composition is added dropwise, the temperature is raised to 90°C and the reaction is carried out for 4 hours, the modified epoxy resin is added, stirred evenly, the reaction is carried out at 110°C for 2 hours, the temperature is lowered to 55°C, 5 parts of triethylamine are added and stirred for 30 minutes, the solvent is removed, and water 1.5 times the mass of the monomer composition is added and stirred at high speed to obtain an epoxy / acrylic core-shell emulsion;

[0027] The silica composition is 1 μm silica to 20 nm silica in a mass ratio of 2:1;

[0028] In the mixed solution of water and ethanol, the volume ratio of water to ethanol is 1:1;

[0029] Example 1: S1: 25 parts of polytetramethylene glycol-1000 were added to 30 parts of acetone, stirred evenly, heated to 70°C, 20 parts of isophorone diisocyanate and 0.5 parts of dibutyltin dilaurate were added, and stirred for reaction for 3 hours to obtain an isocyanate-terminated prepolymer; 2 parts of octahydroxybutyl poss and 2 parts of 1,3-propylene glycol were added, and the mixture was reacted at 70°C for 3 hours, and hydroxyethyl methacrylate was added dropwise and stirred to react until the isocyanate group content of the system reached the theoretical end point as determined by toluene-di-n-butylamine titration method, and the acetone was removed by rotary evaporation to obtain a hyperbranched polyurethane acrylate;

[0030] S2: Trihydroxy heptaoctyl poss, 3-bromopropylene, sodium carbonate, and tetrahydrofuran were mixed evenly and reacted at 60°C for 4 hours to obtain modified poss; the molar ratio of trihydroxy heptaoctyl poss, 3-bromopropylene, and sodium carbonate was 1:1:1; the amount of tetrahydrofuran added was 6 times the total mass of trihydroxy heptaoctyl poss, 3-bromopropylene, and sodium carbonate;

[0031] S3: 15 parts of the silica composition were added to a mixed solution of 80 parts of water and ethanol, the temperature was raised to 60°C, and the mixture was stirred evenly. 1.5 parts of 3-mercaptopropyltriethoxysilane was added, and the mixture was stirred at this temperature for 6 hours. The solvent was removed to obtain mercapto-modified silica;

[0032] S4: Take hexahydroxymethyl melamine, ethanol, and modified poss in a molar ratio of 1:3:3, stir evenly, adjust the pH value to 3, heat to 50°C, stir evenly, keep warm for 2 hours, adjust the pH to 9, start the vacuum pump, control the vacuum degree to 0.06 MPa, and dealcoholize and dehydrate at 100°C under vacuum conditions for 4 hours to obtain a modified etherified amino resin;

[0033] S5: Take 3 parts of modified etherified amino resin, 4 parts of mercapto-modified silica, and 0.1 parts of photoinitiator, mix them evenly to obtain an additive; mix 20 parts of acrylic emulsion, 8 parts of epoxy / acrylic core-shell emulsion, 14 parts of hyperbranched polyurethane acrylate, and 7.1 parts of additives evenly to obtain a reinforced coating: apply the reinforced coating on the surface of the lightweight packaging carton, with a single-side coating amount of 18g / m 2 , irradiate with ultraviolet light for 30 minutes, and dry at 120℃ for 1 hour to obtain a high-strength and lightweight packaging carton.

[0034] Example 2: S1: Add 20 parts of polytetramethylene glycol-1000 to 30 parts of acetone, stir evenly, raise the temperature to 70°C, add 15 parts of isophorone diisocyanate and 0.5 parts of dibutyltin dilaurate, stir and react for 3 hours to obtain an isocyanate-terminated prepolymer; add 2 parts of octahydroxybutyl poss and 1 part of 1,3-propylene glycol, react at 70°C for 3 hours, add hydroxyethyl methacrylate dropwise and stir and react until the isocyanate group content of the system reaches the theoretical end point as determined by toluene-di-n-butylamine titration method, and remove acetone by rotary evaporation to obtain a hyperbranched polyurethane acrylate;

[0035] S2: Trihydroxy heptaoctyl poss, 3-bromopropylene, sodium carbonate, and tetrahydrofuran were mixed evenly and reacted at 60°C for 4 hours to obtain modified poss; the molar ratio of trihydroxy heptaoctyl poss, 3-bromopropylene, and sodium carbonate was 1:1.2:1.2; the amount of tetrahydrofuran added was 6 times the total mass of trihydroxy heptaoctyl poss, 3-bromopropylene, and sodium carbonate;

[0036] S3: 15 parts of the silica composition were added to a mixed solution of 80 parts of water and ethanol, the temperature was raised to 60°C, and the mixture was stirred evenly. 1.5 parts of 3-mercaptopropyltriethoxysilane was added, and the mixture was stirred at this temperature for 6 hours. The solvent was removed to obtain mercapto-modified silica;

[0037] S4: Take hexahydroxymethyl melamine, ethanol, and modified poss in a molar ratio of 1:3:4, stir evenly, adjust the pH value to 3, heat to 50°C, stir evenly, keep warm for 2 hours, adjust the pH to 9, start the vacuum pump, control the vacuum degree to 0.06 MPa, and dealcoholize and dehydrate at 100°C under vacuum conditions for 4 hours to obtain a modified etherified amino resin;

[0038] S5: Take 4 parts of modified etherified amino resin, 4 parts of mercapto-modified silica, and 0.1 parts of photoinitiator, mix them evenly to obtain an additive; mix 25 parts of acrylic emulsion, 10 parts of epoxy / acrylic core-shell emulsion, 15 parts of hyperbranched polyurethane acrylate, and 8.1 parts of additives evenly to obtain a reinforced coating: apply the reinforced coating on the surface of the lightweight packaging carton, with a single-side coating amount of 18g / m 2 , irradiate with ultraviolet light for 30 minutes, and dry at 120℃ for 1 hour to obtain a high-strength and lightweight packaging carton.

[0039] Comparative Example 1 (changing the amount of raw materials added to the enhanced coating, and the remaining method steps are consistent with Example 1): S1: 25 parts of polytetramethylene glycol-1000 are added to 30 parts of acetone, stirred evenly, heated to 70 ° C, 20 parts of isophorone diisocyanate and 0.5 parts of dibutyltin dilaurate are added, and stirred for 3 hours to obtain an isocyanate-terminated prepolymer; 2 parts of octahydroxybutyl poss and 2 parts of 1,3-propylene glycol are added, and the mixture is reacted at 70 ° C for 3 hours. Hydroxyethyl methacrylate is added dropwise and stirred to react until the content of the isocyanate group in the system reaches the theoretical end point by toluene-di-n-butylamine titration method, and the acetone is removed by rotary evaporation to obtain a hyperbranched polyurethane acrylate;

[0040] S2: Trihydroxy heptaoctyl poss, 3-bromopropylene, sodium carbonate, and tetrahydrofuran were mixed evenly and reacted at 60°C for 4 hours to obtain modified poss; the molar ratio of trihydroxy heptaoctyl poss, 3-bromopropylene, and sodium carbonate was 1:1:1; the amount of tetrahydrofuran added was 6 times the total mass of trihydroxy heptaoctyl poss, 3-bromopropylene, and sodium carbonate;

[0041] S3: 15 parts of the silica composition were added to a mixed solution of 80 parts of water and ethanol, the temperature was raised to 60°C, and the mixture was stirred evenly. 1.5 parts of 3-mercaptopropyltriethoxysilane was added, and the mixture was stirred at this temperature for 6 hours. The solvent was removed to obtain mercapto-modified silica;

[0042] S4: Take hexahydroxymethyl melamine, ethanol, and modified poss in a molar ratio of 1:3:3, stir evenly, adjust the pH value to 3, heat to 50°C, stir evenly, keep warm for 2 hours, adjust the pH to 9, start the vacuum pump, control the vacuum degree to 0.06 MPa, and dealcoholize and dehydrate at 100°C under vacuum conditions for 4 hours to obtain a modified etherified amino resin;

[0043] S5: Take 3 parts of modified etherified amino resin, 4 parts of mercapto-modified silica, and 0.1 parts of photoinitiator, mix them evenly to obtain an additive; mix 30 parts of acrylic emulsion, 3 parts of epoxy / acrylic core-shell emulsion, 9 parts of hyperbranched polyurethane acrylate, and 7.1 parts of additives evenly to obtain a reinforced coating: apply the reinforced coating on the surface of the lightweight packaging carton, with a single-side coating amount of 18g / m 2 , irradiate with ultraviolet light for 30 minutes, and dry at 120℃ for 1 hour to obtain a high-strength and lightweight packaging carton.

[0044] Comparative Example 2 (octahydroxybutyl poss replaces 1,3-propylene glycol, and the remaining method steps are consistent with Example 1): S1: 25 parts of polytetramethylene glycol-1000 are added to 30 parts of acetone, stirred evenly, heated to 70 ° C, added 20 parts of isophorone diisocyanate and 0.5 parts of dibutyltin dilaurate, stirred and reacted for 3 hours to obtain an isocyanate-terminated prepolymer; 4 parts of octahydroxybutyl poss are added, reacted at 70 ° C for 3 hours, hydroxyethyl methacrylate is added dropwise and stirred to react until the content of the isocyanate group in the system reaches the theoretical end point by toluene-di-n-butylamine titration method, and the acetone is removed by rotary evaporation to obtain a hyperbranched polyurethane acrylate;

[0045] S2: Trihydroxy heptaoctyl poss, 3-bromopropylene, sodium carbonate, and tetrahydrofuran were mixed evenly and reacted at 60°C for 4 hours to obtain modified poss; the molar ratio of trihydroxy heptaoctyl poss, 3-bromopropylene, and sodium carbonate was 1:1:1; the amount of tetrahydrofuran added was 6 times the total mass of trihydroxy heptaoctyl poss, 3-bromopropylene, and sodium carbonate;

[0046] S3: 15 parts of the silica composition were added to a mixed solution of 80 parts of water and ethanol, the temperature was raised to 60°C, and the mixture was stirred evenly. 1.5 parts of 3-mercaptopropyltriethoxysilane was added, and the mixture was stirred at this temperature for 6 hours. The solvent was removed to obtain mercapto-modified silica;

[0047] S4: Take hexahydroxymethyl melamine, ethanol, and modified poss in a molar ratio of 1:3:3, stir evenly, adjust the pH value to 3, heat to 50°C, stir evenly, keep warm for 2 hours, adjust the pH to 9, start the vacuum pump, control the vacuum degree to 0.06 MPa, and dealcoholize and dehydrate at 100°C under vacuum conditions for 4 hours to obtain a modified etherified amino resin;

[0048] S5: Take 3 parts of modified etherified amino resin, 4 parts of mercapto-modified silica, and 0.1 parts of photoinitiator, mix them evenly to obtain an additive; mix 20 parts of acrylic emulsion, 8 parts of epoxy / acrylic core-shell emulsion, 14 parts of hyperbranched polyurethane acrylate, and 7.1 parts of additives evenly to obtain a reinforced coating: apply the reinforced coating on the surface of the lightweight packaging carton, with a single-side coating amount of 18g / m 2 , irradiate with ultraviolet light for 30 minutes, and dry at 120℃ for 1 hour to obtain a high-strength and lightweight packaging carton.

[0049] Comparative Example 3 (changing the preparation method of the additive, the remaining method steps are consistent with Example 1): S1: 25 parts of polytetramethylene glycol-1000 are added to 30 parts of acetone, stirred evenly, heated to 70 ° C, 20 parts of isophorone diisocyanate and 0.5 parts of dibutyltin dilaurate are added, and stirred for 3 hours to obtain an isocyanate-terminated prepolymer; 2 parts of octahydroxybutyl poss and 2 parts of 1,3-propylene glycol are added, and the mixture is reacted at 70 ° C for 3 hours. Hydroxyethyl methacrylate is added dropwise and stirred to react until the content of the isocyanate group in the system reaches the theoretical end point by toluene-di-n-butylamine titration method, and the acetone is removed by rotary evaporation to obtain a hyperbranched polyurethane acrylate;

[0050] S2: Take hexahydroxymethyl melamine, ethanol, and trihydroxy heptaoctyl poss in a molar ratio of 1:3:3, stir evenly, adjust the pH value to 3, heat to 50°C, stir evenly, keep warm for 2 hours, adjust the pH to 9, start the vacuum pump, control the vacuum degree to 0.06 MPa, and dealcoholize and dehydrate at 100°C under vacuum conditions for 4 hours to obtain a modified etherified amino resin;

[0051] S3: Take 3 parts of modified etherified amino resin and 4 parts of silica composition, mix them evenly to obtain additives; mix 20 parts of acrylic emulsion, 8 parts of epoxy / acrylic core-shell emulsion, 14 parts of hyperbranched polyurethane acrylate, and 7 parts of additives evenly to obtain a reinforcing coating: apply the reinforcing coating on the surface of the lightweight packaging carton, with a single-side coating amount of 18g / m 2 , irradiate with ultraviolet light for 30 minutes, and dry at 120℃ for 1 hour to obtain a high-strength and lightweight packaging carton.

[0052] Comparative Example 4 (changing the amount of raw materials added to the enhanced coating, and the remaining method steps are consistent with Example 1): S1: 25 parts of polytetramethylene glycol-1000 are added to 30 parts of acetone, stirred evenly, heated to 70 ° C, 20 parts of isophorone diisocyanate and 0.5 parts of dibutyltin dilaurate are added, and stirred for 3 hours to obtain an isocyanate-terminated prepolymer; 2 parts of octahydroxybutyl poss and 2 parts of 1,3-propylene glycol are added, and the mixture is reacted at 70 ° C for 3 hours. Hydroxyethyl methacrylate is added dropwise and stirred to react until the content of the isocyanate group in the system reaches the theoretical end point by toluene-di-n-butylamine titration method, and the acetone is removed by rotary evaporation to obtain a hyperbranched polyurethane acrylate;

[0053] S2: Trihydroxy heptaoctyl poss, 3-bromopropylene, sodium carbonate, and tetrahydrofuran were mixed evenly and reacted at 60°C for 4 hours to obtain modified poss; the molar ratio of trihydroxy heptaoctyl poss, 3-bromopropylene, and sodium carbonate was 1:1:1; the amount of tetrahydrofuran added was 6 times the total mass of trihydroxy heptaoctyl poss, 3-bromopropylene, and sodium carbonate;

[0054] S3: 15 parts of the silica composition were added to a mixed solution of 80 parts of water and ethanol, the temperature was raised to 60°C, and the mixture was stirred evenly. 1.5 parts of 3-mercaptopropyltriethoxysilane was added, and the mixture was stirred at this temperature for 6 hours. The solvent was removed to obtain mercapto-modified silica;

[0055] S4: Take hexahydroxymethyl melamine, ethanol, and modified poss in a molar ratio of 1:3:3, stir evenly, adjust the pH value to 3, heat to 50°C, stir evenly, keep warm for 2 hours, adjust the pH to 9, start the vacuum pump, control the vacuum degree to 0.06 MPa, and dealcoholize and dehydrate at 100°C under vacuum conditions for 4 hours to obtain a modified etherified amino resin;

[0056] S5: Take 3 parts of modified etherified amino resin, 4 parts of mercapto-modified silica, and 0.1 parts of photoinitiator, mix them evenly to obtain an additive; mix 10 parts of acrylic emulsion, 15 parts of epoxy / acrylic core-shell emulsion, 17 parts of hyperbranched polyurethane acrylate, and 7.1 parts of additives evenly to obtain a reinforced coating: apply the reinforced coating on the surface of the lightweight packaging carton, with a single-side coating amount of 18g / m 2 , irradiate with ultraviolet light for 30 minutes, and dry at 120℃ for 1 hour to obtain a high-strength and lightweight packaging carton.

[0057] Performance test: Take the high-strength lightweight packaging cartons prepared in Examples 1 to 2 and Comparative Examples 1 to 4; (1) Test the bursting strength in accordance with GB / T6545-1998; (2) Test the static contact angle; (3) Place 600-grit sandpaper on the surface of each carton and drag the sandpaper 10 times under the pressure of a 400g weight, each dragging distance being 20cm, and then test the static contact angle after friction again; see Table 1 for details.

[0058] Table 1:

[0059]

[0060] Conclusion: Comparative Example 1 changes the amount of raw materials added to the enhanced coating, the amount of acrylic emulsion added increases, epoxy / propylene Acid core The added amount of shell emulsion and hyperbranched polyurethane acrylate is reduced, and the performance is reduced, which shows the importance of the raw material ratio; Comparative Example 2 replaces 1,3-propylene glycol with octahydroxybutyl poss, resulting in too high a degree of branching of the hyperbranched polyurethane acrylate and a decrease in performance; Comparative Example 3 changes the preparation method of the additive, and directly uses hexahydroxymethylmelamine, ethanol, and trihydroxyheptaoctyl poss to prepare a modified etherified amino resin, and mixes the modified etherified amino resin and a silica composition to obtain an additive, which reduces the compatibility of the additive with other components, and the overall cross-linking degree is also reduced, resulting in a decrease in performance; Comparative Example 4 increases the added amount of epoxy / acrylic core-shell emulsion, and the performance is not as good as the embodiment; In summary, the high-strength and lightweight packaging carton prepared by the present invention has good bursting strength, strong water resistance, good bonding between the coating and the carton body, and good wear resistance.

[0061] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing a high-strength and lightweight packaging carton, characterized by: The following steps are involved: S1: Mix trihydroxy heptaoctyl poss, 3-bromopropylene, sodium carbonate and tetrahydrofuran evenly, and react at 50-60°C for 3-5h to obtain modified poss; S2: Take the silica composition, add it to a mixed solution of water and ethanol, heat it to 50-60°C, stir it evenly, add 3-mercaptopropyltriethoxysilane, keep it warm and stir it for 4-6 hours, remove the solvent, and obtain mercapto-modified silica; S3: Take hexamethylol melamine, ethanol, and modified poss, stir evenly, adjust the pH value to 3-4, heat to 40-55°C, stir evenly, keep warm and react for 1-2 hours, adjust the pH to 8-10, control the vacuum degree to 0.06-0.09 MPa, and react at 90-105°C under vacuum conditions for 2-4 hours to obtain modified etherified amino resin; S4: Take modified etherified amino resin, mercapto-modified silica, and photoinitiator, mix them evenly to obtain additives; take acrylic emulsion, epoxy / acrylic core-shell emulsion, hyperbranched polyurethane acrylate, and additives, stir them evenly to obtain reinforced coating: apply the reinforced coating on the surface of a lightweight packaging carton, dry and cure it to obtain a high-strength lightweight packaging carton.

2. The method for preparing a high-strength and lightweight packaging carton according to claim 1, characterized in that: The molar ratio of trihydroxyheptaoctyl poss, 3-bromopropylene and sodium carbonate is 1:(1-1.2):(1-1.2); the mercapto-modified silica includes the following raw materials, calculated in parts by mass: 10-15 parts of silica composition, 1-1.5 parts of 3-mercaptopropyltriethoxysilane; the molar ratio of hexahydroxymethylmelamine, ethanol and modified poss is 1:(3-5):(2-4); the additives include the following raw materials, calculated in parts by mass: 3-4 parts of modified etherified amino resin, 2-4 parts of mercapto-modified silica, 0.1-0.2 parts of photoinitiator; the enhanced coating includes the following raw materials, calculated in parts by mass: 15-25 parts of acrylic emulsion, 6-10 parts of epoxy / acrylic core-shell emulsion, 10-15 parts of hyperbranched polyurethane acrylate, and 5-9 parts of additives.

3. The method for preparing a high-strength and lightweight packaging carton according to claim 1, characterized in that: The silicon dioxide composition comprises silicon dioxide with a mass ratio of (1-2):1 with a size of 1-3 μm and silicon dioxide with a size of 10-20 nm.

4. The method for preparing a high-strength and lightweight packaging carton according to claim 1, characterized in that: The preparation of the epoxy / acrylic acid core-shell emulsion comprises the following steps: Step 1: Mix epoxy resin, phthalic anhydride, and dimethylethylenediamine, heat to 130°C for reaction, and add capric acid when the acid value is less than 8mg KOH / g. Cool to 115-120°C, condense and reflux for 2-4 hours to obtain a modified epoxy resin; Step 2: Evenly mix 2,2,3,3,3-pentafluoro-2-fluoropropyl acrylate, acrylic acid, methacrylic acid, octadecyl acrylate, and hydroquinone to obtain a monomer composition; take α-methylstyrene and benzoyl peroxide, dissolve them in propylene glycol methyl ether, heat to 70-80°C, dropwise add the monomer composition, heat to 80-90°C and react for 3-4 hours, add modified epoxy resin, stir evenly, react at 110°C for 1-2 hours, cool to 50-55°C, add triethylamine and stir for 30-60 minutes, remove the solvent, add water, and stir at high speed to obtain an epoxy / acrylic core-shell emulsion.

5. The method for preparing a high-strength and lightweight packaging carton according to claim 4, characterized in that: The epoxy / acrylic core-shell emulsion includes the following raw materials, calculated by mass: 12 to 15 parts of epoxy resin, 2 to 3 parts of phthalic anhydride, 0.04 to 0.06 parts of dimethylethylenediamine, 3 to 4 parts of decanoic acid, 0.8 to 1.5 parts of 2,2,3,3,3-pentafluoro-2-fluoropropyl acrylate, 3 to 4 parts of acrylic acid, 2 to 3 parts of methacrylic acid, 0.4 to 0.6 parts of octadecyl acrylate, 0.01 to 0.02 parts of hydroquinone, 1 to 2 parts of α-methylstyrene, 0.3 to 0.5 parts of benzoyl peroxide, 4 to 5 parts of propylene glycol methyl ether, and 4 to 5 parts of triethylamine; the amount of water added is 1.5 to 2 times the mass of the monomer composition.

6. The method for preparing a high-strength and lightweight packaging carton according to claim 1, characterized in that: The preparation of the hyperbranched polyurethane acrylate comprises the following steps: Add polytetramethylene glycol to acetone and stir evenly, raise the temperature to 70-80°C, add isophorone diisocyanate and dibutyltin dilaurate, stir and react for 2-3 hours to obtain an isocyanate-terminated prepolymer; add a chain extender, react at 60-70°C for 2-3 hours, add hydroxyethyl methacrylate dropwise and stir and react until the content of isocyanate groups in the system reaches the theoretical end point, and remove acetone by rotary evaporation to obtain a hyperbranched polyurethane acrylate.

7. The method for preparing a high-strength and lightweight packaging carton according to claim 6, characterized in that: The hyperbranched polyurethane acrylate comprises the following raw materials, calculated by mass: 20 to 30 parts of polytetramethylene glycol, 20 to 30 parts of acetone, 15 to 20 parts of isophorone diisocyanate, 0.5 to 1 part of dibutyltin dilaurate, and 3 to 5 parts of a chain extender.

8. The method for preparing a high-strength and lightweight packaging carton according to claim 7, characterized in that: The chain extender comprises octahydroxybutyl poss and 1,3-propylene glycol in a mass ratio of (2-3): (1-2).

9. The method for preparing a high-strength and lightweight packaging carton according to claim 1, characterized in that: When the enhanced coating is applied to the surface of lightweight packaging cartons, the coating amount on one side is 15 to 25 g / m 2 The curing process is: ultraviolet irradiation for 20 to 30 minutes, drying at 100 to 120°C for 1 to 2 hours.

10. A high-strength lightweight packaging carton prepared according to the method for preparing a high-strength lightweight packaging carton according to any one of claims 1 to 9.

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