Low-volatility carton material and preparation method thereof
By applying modified polylactic acid and nano-silica composites, the problem of weak bonding between fibers in biomass carton materials has been solved, the mechanical strength and structural stability of the carton have been improved, and high-end packaging needs have been met.
Patent Information
- Application Number
- CN202511191094.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-25
- Publication Date
- 2025-10-10
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
Existing biomass carton materials have weak inter-fiber bonding, insufficient structural stability, and mechanical strength that cannot meet high-end packaging requirements.
Modified polylactic acid and nano-silica composites were used to prepare modified epoxy chain extenders through suspension polymerization. Pulp suspension was prepared by combining wheat straw and bagasse. Methyl cellulose was added and then papermaking and drying were carried out. Finally, low-volatile carton materials were obtained through hot pressing.
It improves the mechanical strength and inter-fiber bonding force of the carton material and enhances the structural stability of the material.
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Figure CN120759153A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of packaging materials, in particular to a low-volatile carton material and a preparation method thereof. Background Art
[0002] As the packaging industry's requirements for sustainable development and environmental protection continue to increase, traditional carton materials face the dual challenges of resource consumption and performance optimization. Most mainstream cartons on the market use wood fiber as the main raw material, and achieve basic strength requirements through multi-layer corrugated structure design, but its production process relies on wood resources, and adhesives, waterproofing agents and other additives used in some processes may release volatile organic compounds, posing an environmental pollution risk. In recent years, biomass conversion materials have become a research hotspot for replacing traditional materials due to their renewability and biodegradability. For example, environmentally friendly cardboard prepared from agricultural waste (such as straw, sugarcane bagasse) and bamboo fiber can reduce dependence on wood resources. However, although existing biomass carton materials have good low volatility properties, they generally have problems such as weak inter-fiber bonding and insufficient structural stability, which makes it difficult for their mechanical strength to meet high-end packaging requirements, limiting their application in high-intensity scenarios. Summary of the Invention
[0003] (1) Technical problems solved
[0004] In view of the shortcomings of the prior art, the present invention provides a low-volatile carton material and a preparation method thereof. The low-volatile carton material prepared by the present invention improves the mechanical strength of the carton material while ensuring low volatility.
[0005] (2) Technical solution
[0006] To achieve the above objectives, the present invention provides the following technical solution: a low-volatile cardboard material, comprising the following components by weight: 30-36 parts by weight of wheat straw, 20-24 parts by weight of bagasse, 3-5 parts by weight of methyl cellulose, 8-12 parts by weight of modified polylactic acid, and 2-4 parts by weight of nano-silicon dioxide.
[0007] Preferably, the preparation method of the modified polylactic acid is as follows: 48-52 g of polylactic acid vacuum-dried at 80° C. for 8-12 h and 0.5-0.7 g of a modified epoxy chain extender are added to an internal mixer, and melt-blended at 170-190° C. and 20-40 rpm for 5-10 min to obtain the modified polylactic acid.
[0008] Preferably, the preparation method of the modified epoxy chain extender comprises the following steps:
[0009] (1) Add 3.66-4.26 g of cis-11-dodecenoic acid to a reactor, heat to 165-175 ° C, add 1.8-2.4 mL of a water-carrying agent and 3.4-3.7 g of hydroxyethylethylenediamine, reflux for 1-3 hours, heat to 220-230 ° C and continue to react for 2.5-4.5 hours. After the reaction is completed, vacuum distillation is performed to obtain an imidazoline intermediate;
[0010] (2) Add 10-10.4 g of 6,7-dihydroxy-2-naphthoic acid, 6.4-6.9 g of imidazoline intermediate, and 0.2-0.28 g of 4-dimethylaminopyridine catalyst to 60-90 mL of sulfolane solvent, stir and mix, heat to reaction temperature, introduce nitrogen protection, react for 5.5-7.5 h, and after the reaction is completed, wash, filter, and vacuum dry to obtain intermediate 1;
[0011] (3) Add 4.3-4.7 g of intermediate 1 and 18.4-18.6 g of epichlorohydrin to 30-50 mL of isopropanol solvent, heat to 45-55 ° C, introduce nitrogen protection, stir and dissolve, then continue to heat to 62-70 ° C, add 0.78-0.82 g of sodium hydroxide, and continue to react for 3-4 hours. After the reaction is completed, remove the solvent by filtration under reduced pressure, wash and vacuum dry to obtain an epoxy functional monomer;
[0012] (4) Add 5.7-5.9 g of 2-amino-1-methylimidazole to 40-60 mL of ethanol solvent, stir and dissolve, add 1.2-1.6 mL of concentrated hydrochloric acid to adjust the pH value to 2-3, introduce nitrogen protection, heat to 90-100 ° C, add 5.2-5.5 mL of formaldehyde solution, 5.4-5.6 g of N-vinyl pyrrolidone, and 0.02-0.04 g of hydroquinone polymerization inhibitor, react for 4-7 hours, and after the reaction is completed, remove the solvent by rotary evaporation, wash and vacuum dry to obtain a Mannich base intermediate;
[0013] (5) Under a nitrogen atmosphere, 2.3-2.5 g of a Mannich base intermediate, 0.03-0.05 g of a triethylamine catalyst, and 0.02-0.04 g of a hydroquinone polymerization inhibitor were added to 50-80 mL of tetrahydrofuran solvent, and the mixture was stirred and mixed. 2.8-3.2 g of acryloxypropyltrimethoxysilane was added thereto, and the mixture was heated to 30-45° C. and reacted for 2.5-4 h. After the reaction was completed, the mixture was filtered, washed, and vacuum-dried to obtain a silane-modified Mannich base monomer;
[0014] (6) under the atmosphere of nitrogen, 0.035-0.045g of activated white clay, 0.1-0.3g of polyvinyl alcohol are added into 15-25mL of deionized water solvent, stirred at 48-54℃ for 20-30min to form a dispersion system, 0.6-1.2g of styrene, 1.7-2g of methyl methacrylate, 0.4-0.8g of silane modified mannich base monomer, 0.9-1.3g of epoxy functional monomer are mixed, 0.03-0.07g of initiator, 0.01-0.03g of chain transfer agent are added, after ultrasonic dissolution, pour into the dispersion system, heat to 76-84℃ for 4.5-6.5h, then heat to 95-105℃ for 2-3h, after the reaction is completed, filter under reduced pressure, wash and vacuum dry to obtain a modified epoxy chain extender.
[0015] Preferably, the water carrying agent in the step (1) is xylene.
[0016] Preferably, the reaction temperature in the step (2) is 178-182℃.
[0017] Preferably, the mass fraction of the formaldehyde solution in the step (4) is 36%-38%.
[0018] Preferably, the initiator in the step (6) is benzoyl peroxide, and the chain transfer agent is dodecyl mercaptan.
[0019] Preferably, the preparation method of the low volatile paper box material is: the wheat straw and sugarcane residue are crushed and then put into water for cooking for 3-5h, after filtration, pulp suspension is obtained by beating, the modified polylactic acid and nano silicon dioxide are dispersed at 1800-2400rpm for 4-8min to obtain a modified polylactic acid nano composite, methyl cellulose and the modified polylactic acid nano composite are added into the pulp suspension, and after stirring at 400-700rpm for 1.5-2.5h, the papermaking machine is injected for papermaking, and the paper obtained by papermaking is dried at 65-75℃, and the low volatile paper box material is obtained by hot pressing process after drying.
[0020] (Three) beneficial technical effects
[0021] The present application uses styrene, methyl methacrylate, silane modified mannich base monomer, epoxy functional monomer as polymerization monomer, and uses suspension polymerization method to prepare modified epoxy chain extender, and then the modified epoxy chain extender and polylactic acid are melt blended to obtain modified polylactic acid, and then the wheat straw and sugarcane residue are used to prepare pulp suspension, and then the modified polylactic acid and nano silicon dioxide are mixed to obtain a modified polylactic acid nano composite, and then methyl cellulose and the modified polylactic acid nano composite are added into the pulp suspension, and after stirring and mixing, the papermaking and drying are carried out, and then the low volatile paper box material is obtained by hot pressing process after drying.
[0022] The epoxy group in the modified epoxy chain extender can react with the terminal carboxyl or hydroxyl group of polylactic acid to form an ester bond or an ether bond, thereby increasing the molecular weight of polylactic acid, realizing the expansion and branching of the polylactic acid molecular chain, increasing the chain entanglement density, and thereby improving the mechanical properties of polylactic acid; the bicyclic aromatic structure of the naphthyl group in the epoxy functional monomer has greater steric hindrance than the benzene ring, which can limit the rotation and slip of the polylactic acid molecular chain, increase the chain segment rigidity, and thereby improve the mechanical properties of polylactic acid; the silane group in the silane-modified Mannich base monomer connects the silica filler to the polylactic acid molecular chain through coupling with the silica filler, further improving the mechanical properties; the nitrogen atoms in the pyrrole group and the imidazole group act as hydrogen bond acceptors, enhancing the hydrogen bonding between polylactic acid and pulp fiber materials, and improving the bonding force between fibers; through the above beneficial effects, the mechanical strength of the carton material is synergistically improved. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 This is the synthetic reaction formula for epoxy functional monomers.
[0024] Figure 2 This is the synthetic reaction formula for silane-modified Mannich base monomer. DETAILED DESCRIPTION
[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.
[0026] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific embodiments.
[0027] Example 1
[0028] (1) Add 3.66 g of cis-11-dodecenoic acid to a reactor, heat to 165° C., add 1.8 mL of xylene water-carrying agent and 3.4 g of hydroxyethylethylenediamine, reflux for 1 h, heat to 220° C., and continue to react for 2.5 h. After the reaction is completed, vacuum distillation is performed to obtain an imidazoline intermediate;
[0029] (2) Add 10 g of 6,7-dihydroxy-2-naphthoic acid, 6.4 g of imidazoline intermediate, and 0.2 g of 4-dimethylaminopyridine catalyst to 60 mL of sulfolane solvent, stir and mix, heat to 178 ° C, introduce nitrogen protection, react for 5.5 h, and after the reaction is completed, wash, filter and vacuum dry to obtain intermediate 1;
[0030] (3) Add 4.3 g of intermediate 1 and 18.4 g of epichlorohydrin to 30 mL of isopropanol solvent, heat to 45° C., introduce nitrogen protection, stir and dissolve, then continue to heat to 62° C., add 0.78 g of sodium hydroxide, and continue to react for 3 h. After the reaction is completed, remove the solvent by filtration under reduced pressure, wash and vacuum dry to obtain an epoxy functional monomer;
[0031] (4) Add 5.7 g of 2-amino-1-methylimidazole to 40 mL of ethanol solvent, stir and dissolve, add 1.2 mL of concentrated hydrochloric acid to adjust the pH value to 2, introduce nitrogen protection, heat to 90° C., add 5.2 mL of 36% formaldehyde solution, 5.4 g of N-vinyl pyrrolidone, and 0.02 g of hydroquinone inhibitor, and react for 4 h. After the reaction is completed, remove the solvent by rotary evaporation, wash and vacuum dry to obtain a Mannich base intermediate;
[0032] (5) Under a nitrogen atmosphere, 2.3 g of a Mannich base intermediate, 0.03 g of a triethylamine catalyst, and 0.02 g of a hydroquinone polymerization inhibitor were added to 50 mL of tetrahydrofuran solvent, and the mixture was stirred and mixed. 2.8 g of acryloxypropyltrimethoxysilane was added thereto, and the mixture was heated to 30° C. and reacted for 2.5 h. After the reaction was completed, the mixture was filtered, washed, and vacuum-dried to obtain a silane-modified Mannich base monomer;
[0033] (6) Under nitrogen atmosphere, 0.035 g of activated clay and 0.1 g of polyvinyl alcohol were added to 15 mL of deionized water solvent, and stirred at 48 ° C for 20 min to form a dispersion system. 0.6 g of styrene, 1.7 g of methyl methacrylate, 0.4 g of silane-modified Mannich base monomer, and 0.9 g of epoxy functional monomer were mixed, and 0.03 g of benzoyl peroxide initiator and 0.01 g of dodecyl mercaptan chain transfer agent were added thereto. After ultrasonic dissolution, the mixture was poured into the dispersion system, heated to 76 ° C for reaction for 4.5 h, and then heated to 95 ° C for aging for 2 h. After the reaction was completed, the mixture was filtered under reduced pressure, washed, and vacuum dried to obtain a modified epoxy chain extender;
[0034] (7) 48 g of polylactic acid dried under vacuum at 80° C. for 8 h and 0.5 g of a modified epoxy chain extender were added to an internal mixer and melt-blended at 170° C. and 20 rpm for 5 min to obtain modified polylactic acid;
[0035] (8) 30 parts by weight of wheat straw and 20 parts by weight of bagasse were crushed and put into water and cooked for 3 hours. After filtration, pulp suspension was obtained. 8 parts by weight of modified polylactic acid and 2 parts by weight of nano-silicon dioxide were dispersed at 1800 rpm for 4 minutes to obtain a modified polylactic acid nanocomposite. 3 parts by weight of methyl cellulose and the modified polylactic acid nanocomposite were added to the pulp suspension. After stirring at 400 rpm for 1.5 hours, the mixture was injected into a papermaking machine for papermaking. The paper obtained by papermaking was dried at 65°C. After drying, a low-volatility paper box material was obtained by a hot-pressing process.
[0036] Example 2
[0037] (1) 4.26 g of cis-dodec-11-enoic acid was added to a reactor, and the temperature was raised to 175°C. 2.4 mL of xylene water-carrying agent and 3.7 g of hydroxyethyl ethylenediamine were added thereto. After refluxing for 3 hours, the temperature was raised to 230°C and the reaction was continued for 4.5 hours. After the reaction was completed, distillation was performed under reduced pressure to obtain an imidazoline intermediate;
[0038] (2) 10.4 g of 6,7-dihydroxy-2-naphthoic acid, 6.9 g of the imidazoline intermediate, and 0.28 g of 4-dimethylaminopyridine catalyst were added to 90 mL of sulfolane solvent, and stirred and mixed. The temperature was raised to 182°C, and nitrogen was introduced for protection. After the reaction was continued for 7.5 hours, the reaction was completed. After washing, filtration, and vacuum drying, an intermediate 1 was obtained.
[0039] (3) 4.7 g of the intermediate 1 and 18.6 g of epichlorohydrin were added to 50 mL of isopropyl alcohol solvent. After stirring and dissolving, the temperature was raised to 70°C, and 0.82 g of sodium hydroxide was added thereto. After the reaction was continued for 4 hours, the reaction was completed. After removing the solvent by suction filtration under reduced pressure, washing, and vacuum drying, an epoxy-functional monomer was obtained.
[0040] (4) 5.9 g of 2-amino-1-methylimidazole was added to 60 mL of ethanol solvent, and stirred and dissolved. 1.6 mL of concentrated hydrochloric acid was added to adjust the pH to 3, and nitrogen was introduced for protection. After the temperature was raised to 100°C, 5.5 mL of a 38% mass fraction formaldehyde solution, 5.6 g of N-vinylpyrrolidone, and 0.04 g of hydroquinone polymerization inhibitor were added thereto. After the reaction was continued for 7 hours, the reaction was completed. After removing the solvent by rotary evaporation, washing, and vacuum drying, a Mannich base intermediate was obtained.
[0041] (5) Under a nitrogen atmosphere, 2.5 g of the Mannich base intermediate, 0.05 g of triethylamine catalyst, and 0.04 g of hydroquinone polymerization inhibitor were added to 80 mL of tetrahydrofuran solvent, and stirred and mixed. 3.2 g of acryloyloxypropyltrimethoxysilane was added thereto, and the temperature was raised to 45°C. After the reaction was continued for 4 hours, the reaction was completed. After filtration, washing, and vacuum drying, a silane-modified Mannich base monomer was obtained.
[0042] (6) Under nitrogen atmosphere, 0.045 g of activated clay and 0.3 g of polyvinyl alcohol were added to 25 mL of deionized water solvent, and stirred at 54 ° C for 30 min to form a dispersion system. 1.2 g of styrene, 2 g of methyl methacrylate, 0.8 g of silane-modified Mannich base monomer, and 1.3 g of epoxy functional monomer were mixed, and 0.07 g of benzoyl peroxide initiator and 0.03 g of dodecyl mercaptan chain transfer agent were added thereto. After ultrasonic dissolution, the mixture was poured into the dispersion system, heated to 84 ° C for reaction for 6.5 h, and then heated to 105 ° C for aging for 3 h. After the reaction was completed, the mixture was filtered under reduced pressure, washed and vacuum dried to obtain a modified epoxy chain extender;
[0043] (7) 52 g of polylactic acid and 0.7 g of modified epoxy chain extender dried under vacuum at 85°C for 12 h were added to an internal mixer and melt-blended at 190°C and 40 rpm for 10 min to obtain modified polylactic acid;
[0044] (8) 36 parts by weight of wheat straw and 24 parts by weight of bagasse were crushed and put into water for steaming for 5 hours, filtered and pulped to obtain a pulp suspension, 12 parts by weight of modified polylactic acid and 4 parts by weight of nano-silicon dioxide were dispersed at 2400 rpm for 8 minutes to obtain a modified polylactic acid nanocomposite, 5 parts by weight of methyl cellulose and modified polylactic acid nanocomposite were added to the pulp suspension, stirred at 700 rpm for 2.5 hours, and then injected into a papermaking machine for papermaking, and the paper sheets obtained were dried at 75°C. After drying, they were subjected to a hot pressing process to obtain a low-volatile carton material.
[0045] Example 3
[0046] (1) Add 3.96 g of cis-11-dodecenoic acid to a reactor, heat to 170° C., add 2.1 mL of xylene water-carrying agent and 3.55 g of hydroxyethylethylenediamine, reflux for 2 h, heat to 225° C., and continue to react for 3.5 h. After the reaction is completed, vacuum distillation is performed to obtain an imidazoline intermediate;
[0047] (2) Add 10.2 g of 6,7-dihydroxy-2-naphthoic acid, 6.65 g of imidazoline intermediate, and 0.24 g of 4-dimethylaminopyridine catalyst to 75 mL of sulfolane solvent, stir and mix, heat to 180° C., introduce nitrogen protection, react for 6.5 h, and after the reaction is completed, wash, filter, and vacuum dry to obtain intermediate 1;
[0048] (3) Add 4.5 g of intermediate 1 and 18.5 g of epichlorohydrin to 40 mL of isopropanol solvent, heat to 50° C., introduce nitrogen protection, stir and dissolve, then continue to heat to 66° C., add 0.8 g of sodium hydroxide, and continue to react for 3.5 hours. After the reaction is completed, remove the solvent by filtration under reduced pressure, wash and vacuum dry to obtain an epoxy functional monomer;
[0049] (4) Add 5. g of 2-amino-1-methylimidazole to 50 mL of ethanol solvent, stir and dissolve, add 1.4 mL of concentrated hydrochloric acid to adjust the pH to 2.5, introduce nitrogen protection, heat to 95° C., add 5.4 mL of 37% formaldehyde solution, 5.5 g of N-vinyl pyrrolidone, and 0.03 g of hydroquinone inhibitor, and react for 5.5 h. After the reaction is completed, remove the solvent by rotary evaporation, wash and vacuum dry to obtain a Mannich base intermediate;
[0050] (5) Under nitrogen atmosphere, 2.4 g of Mannich base intermediate, 0.04 g of triethylamine catalyst, and 0.03 g of hydroquinone polymerization inhibitor were added to 65 mL of tetrahydrofuran solvent, and the mixture was stirred and mixed. 3 g of acryloxypropyltrimethoxysilane was added thereto, and the temperature was raised to 38° C. and reacted for 3.2 h. After the reaction was completed, the mixture was filtered, washed, and vacuum-dried to obtain a silane-modified Mannich base monomer;
[0051] (6) Under nitrogen atmosphere, 0.04 g of activated clay and 0.2 g of polyvinyl alcohol were added to 20 mL of deionized water solvent, and stirred at 51 ° C for 25 min to form a dispersion system. 0.9 g of styrene, 1.85 g of methyl methacrylate, 0.6 g of silane-modified Mannich base monomer, and 1.1 g of epoxy functional monomer were mixed, and 0.05 g of benzoyl peroxide initiator and 0.02 g of dodecyl mercaptan chain transfer agent were added thereto. After ultrasonic dissolution, the mixture was poured into the dispersion system, heated to 80 ° C for reaction for 5.5 h, and then heated to 100 ° C for aging for 2.5 h. After the reaction was completed, the mixture was filtered under reduced pressure, washed, and vacuum dried to obtain a modified epoxy chain extender;
[0052] (7) 50 g of polylactic acid and 0.6 g of modified epoxy chain extender dried under vacuum at 82°C for 10 h were added to an internal mixer and melt-blended at 180°C and 30 rpm for 8 min to obtain modified polylactic acid;
[0053] (8) 33 parts by weight of wheat straw and 22 parts by weight of sugarcane bagasse were crushed and put into water for cooking for 4 hours, filtered and pulped to obtain a pulp suspension, 10 parts by weight of modified polylactic acid and 3 parts by weight of nano-silicon dioxide were dispersed at 2100 rpm for 6 minutes to obtain a modified polylactic acid nanocomposite, 4 parts by weight of methyl cellulose and modified polylactic acid nanocomposite were added to the pulp suspension, stirred at 550 rpm for 2 hours, and then injected into a papermaking machine for papermaking, and the paper sheets obtained were dried at 70°C. After drying, they were subjected to a hot pressing process to obtain a low-volatile carton material.
[0054] Example 4
[0055] (1) Add 3.66 g of cis-11-dodecenoic acid to a reactor, heat to 165° C., add 1.8 mL of xylene water-carrying agent and 3.4 g of hydroxyethylethylenediamine, reflux for 1 h, heat to 220° C., and continue to react for 2.5 h. After the reaction is completed, vacuum distillation is performed to obtain an imidazoline intermediate;
[0056] (2) Add 10 g of 6,7-dihydroxy-2-naphthoic acid, 6.4 g of imidazoline intermediate, and 0.2 g of 4-dimethylaminopyridine catalyst to 60 mL of sulfolane solvent, stir and mix, heat to 178 ° C, introduce nitrogen protection, react for 5.5 h, and after the reaction is completed, wash, filter and vacuum dry to obtain intermediate 1;
[0057] (3) Add 4.3 g of intermediate 1 and 18.4 g of epichlorohydrin to 30 mL of isopropanol solvent, heat to 45° C., introduce nitrogen protection, stir and dissolve, then continue to heat to 62° C., add 0.78 g of sodium hydroxide, and continue to react for 3 h. After the reaction is completed, remove the solvent by filtration under reduced pressure, wash and vacuum dry to obtain an epoxy functional monomer;
[0058] (4) Add 5.9 g of 2-amino-1-methylimidazole to 60 mL of ethanol solvent, stir and dissolve, add 1.6 mL of concentrated hydrochloric acid to adjust the pH value to 3, introduce nitrogen protection, heat to 100° C., add 5.5 mL of 38% formaldehyde solution, 5.6 g of N-vinyl pyrrolidone, and 0.04 g of hydroquinone inhibitor, and react for 7 h. After the reaction is completed, remove the solvent by rotary evaporation, wash and vacuum dry to obtain a Mannich base intermediate;
[0059] (5) Under a nitrogen atmosphere, 2.5 g of a Mannich base intermediate, 0.05 g of a triethylamine catalyst, and 0.04 g of a hydroquinone inhibitor were added to 80 mL of tetrahydrofuran solvent, and the mixture was stirred and mixed. 3.2 g of acryloxypropyltrimethoxysilane was added thereto, and the mixture was heated to 45° C. and reacted for 4 h. After the reaction was completed, the mixture was filtered, washed, and vacuum-dried to obtain a silane-modified Mannich base monomer;
[0060] (6) Under nitrogen atmosphere, 0.045 g of activated clay and 0.3 g of polyvinyl alcohol were added to 25 mL of deionized water solvent, and stirred at 54 ° C for 30 min to form a dispersion system. 1.2 g of styrene, 2 g of methyl methacrylate, 0.8 g of silane-modified Mannich base monomer, and 1.3 g of epoxy functional monomer were mixed, and 0.07 g of benzoyl peroxide initiator and 0.03 g of dodecyl mercaptan chain transfer agent were added thereto. After ultrasonic dissolution, the mixture was poured into the dispersion system, heated to 84 ° C for reaction for 6.5 h, and then heated to 105 ° C for aging for 3 h. After the reaction was completed, the mixture was filtered under reduced pressure, washed and vacuum dried to obtain a modified epoxy chain extender;
[0061] (7) 50 g of polylactic acid and 0.6 g of modified epoxy chain extender dried under vacuum at 82°C for 10 h were added to an internal mixer and melt-blended at 180°C and 30 rpm for 8 min to obtain modified polylactic acid;
[0062] (8) 33 parts by weight of wheat straw and 22 parts by weight of sugarcane bagasse were crushed and put into water for cooking for 4 hours, filtered and pulped to obtain a pulp suspension, 10 parts by weight of modified polylactic acid and 3 parts by weight of nano-silicon dioxide were dispersed at 2100 rpm for 6 minutes to obtain a modified polylactic acid nanocomposite, 4 parts by weight of methyl cellulose and modified polylactic acid nanocomposite were added to the pulp suspension, stirred at 550 rpm for 2 hours, and then injected into a papermaking machine for papermaking, and the paper sheets obtained were dried at 70°C. After drying, they were subjected to a hot pressing process to obtain a low-volatile carton material.
[0063] Example 5
[0064] (1) Add 3.96 g of cis-11-dodecenoic acid to a reactor, heat to 170° C., add 2.1 mL of xylene water-carrying agent and 3.55 g of hydroxyethylethylenediamine, reflux for 2 h, heat to 225° C., and continue to react for 3.5 h. After the reaction is completed, vacuum distillation is performed to obtain an imidazoline intermediate;
[0065] (2) Add 10.2 g of 6,7-dihydroxy-2-naphthoic acid, 6.65 g of imidazoline intermediate, and 0.24 g of 4-dimethylaminopyridine catalyst to 75 mL of sulfolane solvent, stir and mix, heat to 180° C., introduce nitrogen protection, react for 6.5 h, and after the reaction is completed, wash, filter, and vacuum dry to obtain intermediate 1;
[0066] (3) Add 4.5 g of intermediate 1 and 18.5 g of epichlorohydrin to 40 mL of isopropanol solvent, heat to 50° C., introduce nitrogen protection, stir and dissolve, then continue to heat to 66° C., add 0.8 g of sodium hydroxide, and continue to react for 3.5 hours. After the reaction is completed, remove the solvent by filtration under reduced pressure, wash and vacuum dry to obtain an epoxy functional monomer;
[0067] (4) Add 5.7 g of 2-amino-1-methylimidazole to 40 mL of ethanol solvent, stir and dissolve, add 1.2 mL of concentrated hydrochloric acid to adjust the pH value to 2, introduce nitrogen protection, heat to 90° C., add 5.2 mL of 36% formaldehyde solution, 5.4 g of N-vinyl pyrrolidone, and 0.02 g of hydroquinone inhibitor, and react for 4 h. After the reaction is completed, remove the solvent by rotary evaporation, wash and vacuum dry to obtain a Mannich base intermediate;
[0068] (5) Under a nitrogen atmosphere, 2.3 g of a Mannich base intermediate, 0.03 g of a triethylamine catalyst, and 0.02 g of a hydroquinone polymerization inhibitor were added to 50 mL of tetrahydrofuran solvent, and the mixture was stirred and mixed. 2.8 g of acryloxypropyltrimethoxysilane was added thereto, and the mixture was heated to 30° C. and reacted for 2.5 h. After the reaction was completed, the mixture was filtered, washed, and vacuum-dried to obtain a silane-modified Mannich base monomer;
[0069] (6) Under nitrogen atmosphere, 0.035 g of activated clay and 0.1 g of polyvinyl alcohol were added to 15 mL of deionized water solvent, and stirred at 48 ° C for 20 min to form a dispersion system. 0.6 g of styrene, 1.7 g of methyl methacrylate, 0.4 g of silane-modified Mannich base monomer, and 0.9 g of epoxy functional monomer were mixed, and 0.03 g of benzoyl peroxide initiator and 0.01 g of dodecyl mercaptan chain transfer agent were added thereto. After ultrasonic dissolution, the mixture was poured into the dispersion system, heated to 76 ° C for reaction for 4.5 h, and then heated to 95 ° C for aging for 2 h. After the reaction was completed, the mixture was filtered under reduced pressure, washed, and vacuum dried to obtain a modified epoxy chain extender;
[0070] (7) 52 g of polylactic acid and 0.7 g of modified epoxy chain extender dried under vacuum at 85°C for 12 h were added to an internal mixer and melt-blended at 190°C and 40 rpm for 10 min to obtain modified polylactic acid;
[0071] (8) 36 parts by weight of wheat straw and 24 parts by weight of bagasse were crushed and put into water for steaming for 5 hours, filtered and pulped to obtain a pulp suspension, 12 parts by weight of modified polylactic acid and 4 parts by weight of nano-silicon dioxide were dispersed at 2400 rpm for 8 minutes to obtain a modified polylactic acid nanocomposite, 5 parts by weight of methyl cellulose and modified polylactic acid nanocomposite were added to the pulp suspension, stirred at 700 rpm for 2.5 hours, and then injected into a papermaking machine for papermaking, and the paper sheets obtained were dried at 75°C. After drying, they were subjected to a hot pressing process to obtain a low-volatile carton material.
[0072] Comparative Example 1
[0073] Compared with Example 5, this comparative example differs in that step (6) does not contain a silane-modified Mannich base monomer.
[0074] Comparative Example 2
[0075] Compared with Example 5, this comparative example differs in that glycidyl methacrylate is used instead of the epoxy functional monomer in step (6).
[0076] The low-volatile carton materials used in Examples 1-5 and Comparative Examples 1-2 were tested for flat crush strength, edge crush strength, and carton burst resistance using a cardboard flat crush tester, a cardboard edge crush tester, and a carton burst tester. Flat crush strength was tested according to GB / T 2679.6, edge crush strength was tested according to GB / T 6546, and burst resistance was tested according to GB / T 454-2002. The test results are shown in Table 1.
[0077] Table 1: Carton material performance test.
[0078]
[0079]
[0080] As can be seen from Table 1, the low-volatile carton materials in Examples 1-5 of the present invention have better mechanical strength than the low-volatile carton materials in Comparative Examples 1-2.
[0081] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.
[0082] The above examples are only used to illustrate the technical solutions of the present application, but not limit the present application; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can be modified, or some technical features can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.
[0083] Those skilled in the art should understand that the above only describes several specific embodiments of the present application, but not all embodiments. It should be noted that many modifications and improvements can be made by those skilled in the art, and all modifications and improvements that do not exceed the scope of the claims should be considered as the protection scope of the present application.
Claims
1. A low-volatile carton material, characterized in that: The invention comprises the following components by weight: 30-36 parts by weight of wheat straw, 20-24 parts by weight of bagasse, 3-5 parts by weight of methyl cellulose, 8-12 parts by weight of modified polylactic acid, and 2-4 parts by weight of nano silicon dioxide.
2. The low-volatile carton material according to claim 1, characterized in that: The preparation method of the modified polylactic acid is as follows: 48-52 g of polylactic acid vacuum-dried at 80-85° C. for 8-12 hours and 0.5-0.7 g of a modified epoxy chain extender are added to an internal mixer, and melt-blended at 170-190° C. and 20-40 rpm for 5-10 minutes to obtain the modified polylactic acid.
3. The low-volatile carton material according to claim 2, characterized in that: The preparation method of the modified epoxy chain extender comprises the following steps: (1) Add 3.66-4.26 g of cis-11-dodecenoic acid to a reactor, heat to 165-175 ° C, add 1.8-2.4 mL of a water-carrying agent and 3.4-3.7 g of hydroxyethylethylenediamine, reflux for 1-3 hours, heat to 220-230 ° C and continue to react for 2.5-4.5 hours. After the reaction is completed, vacuum distillation is performed to obtain an imidazoline intermediate; (2) Add 10-10.4 g of 6,7-dihydroxy-2-naphthoic acid, 6.4-6.9 g of imidazoline intermediate, and 0.2-0.28 g of 4-dimethylaminopyridine catalyst to 60-90 mL of sulfolane solvent, stir and mix, heat to reaction temperature, introduce nitrogen protection, react for 5.5-7.5 h, and after the reaction is completed, wash, filter, and vacuum dry to obtain intermediate 1; (3) Add 4.3-4.7 g of intermediate 1 and 18.4-18.6 g of epichlorohydrin to 30-50 mL of isopropanol solvent, heat to 45-55 ° C, introduce nitrogen protection, stir and dissolve, then continue to heat to 62-70 ° C, add 0.78-0.82 g of sodium hydroxide, and continue to react for 3-4 hours. After the reaction is completed, remove the solvent by filtration under reduced pressure, wash and vacuum dry to obtain an epoxy functional monomer; (4) Add 5.7-5.9 g of 2-amino-1-methylimidazole to 40-60 mL of ethanol solvent, stir and dissolve, add 1.2-1.6 mL of concentrated hydrochloric acid to adjust the pH value to 2-3, introduce nitrogen protection, heat to 90-100 ° C, add 5.2-5.5 mL of formaldehyde solution, 5.4-5.6 g of N-vinyl pyrrolidone, and 0.02-0.04 g of hydroquinone polymerization inhibitor, react for 4-7 hours, and after the reaction is completed, remove the solvent by rotary evaporation, wash and vacuum dry to obtain a Mannich base intermediate; (5) Under a nitrogen atmosphere, 2.3-2.5 g of a Mannich base intermediate, 0.03-0.05 g of a triethylamine catalyst, and 0.02-0.04 g of a hydroquinone polymerization inhibitor were added to 50-80 mL of tetrahydrofuran solvent, and the mixture was stirred and mixed. 2.8-3.2 g of acryloxypropyltrimethoxysilane was added thereto, and the mixture was heated to 30-45° C. and reacted for 2.5-4 h. After the reaction was completed, the mixture was filtered, washed, and vacuum-dried to obtain a silane-modified Mannich base monomer; (6) Under nitrogen atmosphere, 0.035-0.045 g of activated clay and 0.1-0.3 g of polyvinyl alcohol were added to 15-25 mL of deionized water solvent, and stirred at 48-54 ° C for 20-30 min to form a dispersion system. 0.6-1.2 g of styrene, 1.7-2 g of methyl methacrylate, 0.4-0.8 g of silane-modified Mannich base monomer, and 0.9-1.3 g of epoxy functional monomer were mixed, and 0.03-0.07 g of initiator and 0.01-0.03 g of chain transfer agent were added thereto. After ultrasonic dissolution, the mixture was poured into the dispersion system, heated to 76-84 ° C for reaction for 4.5-6.5 h, and then heated to 95-105 ° C for aging for 2-3 h. After the reaction was completed, the mixture was filtered under reduced pressure, washed, and vacuum dried to obtain a modified epoxy chain extender.
4. The low-volatile carton material according to claim 3, characterized in that: The water-carrying agent in step (1) is xylene.
5. The low-volatile carton material according to claim 3, characterized in that: The reaction temperature in step (2) is 178-182°C.
6. The low-volatile carton material according to claim 3, characterized in that: The mass fraction of the formaldehyde solution in step (4) is 36%-38%.
7. The low-volatile carton material according to claim 3, characterized in that: In the step (6), the initiator is benzoyl peroxide and the chain transfer agent is dodecyl mercaptan.
8. A method for preparing the low-volatile carton material according to any one of claims 1 to 7, characterized in that: The preparation method of the low-volatile cardboard material comprises the following steps: pulverizing wheat straw and bagasse, boiling them in water for 3-5 hours, filtering and beating the pulp to obtain a pulp suspension, dispersing modified polylactic acid and nano-silicon dioxide at 1800-2400 rpm for 4-8 minutes to obtain a modified polylactic acid nanocomposite, adding methyl cellulose and the modified polylactic acid nanocomposite to the pulp suspension, stirring at 400-700 rpm for 1.5-2.5 hours, injecting the pulp into a papermaking machine for papermaking, drying the paper sheets obtained at 65-75°C, and subjecting the drying to a hot pressing process to obtain the low-volatile cardboard material.
Citation Information
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CN121949689A