A modified stripping agent for papermaking and preparation method thereof

Abstract

The present invention relates to the field of strippers, and in particular to a method for preparing a modified stripper for papermaking. The modified stripper for papermaking is prepared from the following raw materials in parts by weight: 45-55 parts of vinyl silicone oil, 2-4 parts of vinyltrimethylsilane, 2-4 parts of OP-10 emulsifier, 10-15 parts of modified polyurethane emulsion, 8-12 parts of butyl acrylate, 6-8 parts of octadecyl acrylate, and the like. The present invention achieves multi-dimensional optimization of stripper performance by innovatively designing an environmentally friendly material system and synergizing with dynamic functional components, combined with specific process regulation. Compared with the prior art, the present invention adopts a novel hydrophobic structure and an intelligent response network, significantly improving product stability and safety. At the same time, by strengthening interfacial bonding ability, the stripping force is ensured to be precisely controllable, and production and maintenance costs are reduced. The modified stripper is suitable for high-demand scenarios such as food packaging and high-speed paper machines, and has broad market application prospects.

Description

Technical Field

[0001] The present invention relates to the field of stripping agents, in particular to a modified stripping agent for papermaking and a preparation method thereof. Background Art

[0002] In the papermaking industry, release agents are a key auxiliary agent that improves paper production efficiency and finished product quality. Their main function is to reduce the adhesion between paper and the forming mold, drying cylinder or pressure roller, thereby avoiding paper tearing, surface damage or production interruption. With the development of high-speed papermaking technology, the performance requirements of release agents are increasing.

[0003] The main components of stripping agents are silicone oil, emulsifiers and polyurethane substances. Although silicone-based stripping agents have good lubricity, they are prone to oxidative decomposition in high temperature or high humidity environments, resulting in unstable stripping effects. Although polyurethane stripping agents can improve film-forming properties, the residues may affect the subsequent printing or coating performance of the paper.

[0004] In the existing technology, superhydrophobicity is achieved by adding perfluorinated compounds, which leads to the risk of persistent environmental pollution and biological toxicity problems in the materials. Although non-fluorinated superhydrophobic materials can increase the contact angle, the flexibility of their molecular chains decreases, which leads to increased brittleness of the film and makes it difficult to withstand the mechanical shear force of high-speed paper machines. Traditional strippers also have poor wear resistance, which affects the continuous production of high-speed paper machines.

[0005] Therefore, according to the above-mentioned related technologies, there is an urgent need to develop a modified stripping agent for papermaking and a preparation method thereof. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to propose a modified stripping agent for papermaking and a preparation method thereof, so as to solve the problems of poor environmental compliance, insufficient performance stability and poor wear resistance in the prior art.

[0007] Based on the above purpose, the present invention provides a modified stripping agent for papermaking and a preparation method thereof.

[0008] A modified stripping agent for papermaking is prepared from the following raw materials in parts by weight: 45-55 parts of vinyl silicone oil, 2-4 parts of vinyltrimethylsilane, 2-4 parts of OP-10 emulsifier, 10-15 parts of modified polyurethane emulsion, 8-12 parts of butyl acrylate, 6-8 parts of octadecyl acrylate, 1-3 parts of polyamide-amine dendrimer, 0.5-1 part of potassium persulfate, 1-1.5 parts of azobisisobutyronitrile, and 1-3 parts of glycidyl methacrylate.

[0009] The modified polyurethane emulsion is prepared from modified polyisocyanate and polyol containing phosphate groups.

[0010] A method for preparing a modified stripping agent for papermaking, the preparation method is as follows:

[0011] Step S1: Under a nitrogen atmosphere, vinyl silicone oil, vinyl trimethylsilane, and OP-10 emulsifier are added to deionized water, the temperature is raised to 20-30°C, and stirred for 20-40 minutes at a rotation speed of 1800-2200 rpm. The temperature is then raised to 70-80°C, potassium persulfate is added, and the mixture is stirred for 2-3 hours at a rotation speed of 400-600 rpm. The reaction is completed to obtain a silicone emulsion mixture;

[0012] Step S2: Add the silicone emulsion mixture to a flask, raise the temperature to 70-80°C, rotate at 200-400 rpm, add modified polyurethane emulsion, butyl acrylate, polyamide-amine dendrimer, octadecyl acrylate and azobisisobutyronitrile, react for 3-5 hours, cool to 50-60°C, add glycidyl methacrylate, stir and react for 50-70 minutes, rotate at 150-250 rpm, add 10 wt% citric acid solution, adjust the pH to 6.5-7, and filter to obtain a modified stripping agent;

[0013] Potassium persulfate and azobisisobutyronitrile are used as initiators, and glycidyl methacrylate is used as a crosslinking agent;

[0014] By constructing a fluorine-free super-hydrophobic organosilicon hybrid system, long-chain alkyl and polyamide-amine dendrimers are used to synergistically form a micro-nano rough structure to increase the contact angle, avoid the use of traditional perfluorinated compounds, and avoid the risk of persistent environmental pollution.

[0015] By optimizing the formula, discarding the toxic components in traditional stripping agents, and introducing biocompatible raw materials butyl acrylate and glycidyl methacrylate, the toxicity of paper is reduced and the application range of paper is expanded.

[0016] Preferably, in step S1, the mass ratio of vinyl silicone oil, vinyltrimethylsilane, OP-10 emulsifier and potassium persulfate is 45-55:2-4:2-4:0.5-1.

[0017] Preferably, the mass ratio of the silicone emulsion mixture, modified polyurethane emulsion, butyl acrylate, polyamide-amine dendrimer, octadecyl acrylate, azobisisobutyronitrile and glycidyl methacrylate in step S2 is 50-60:12-15:8-10:1-3:6-8:1-1.5:1-3.

[0018] Preferably, the modified polyurethane emulsion is prepared as follows:

[0019] Add modified polyisocyanate and phosphate group-containing polyol into a three-necked flask, heat to 80-90°C, react for 2-4h, cool to 35-55°C, add dimethylol propionic acid and 1,4-butanediol, heat to 70-90°C, react for 60-90min, cool to 35-50°C, add catalyst dibutyltin dilaurate, heat to 60-80°C again, react for 3-5h, complete the reaction, cool to 30-50°C, neutralize with triethylamine, emulsify with deionized water, and distill under reduced pressure to obtain a modified polyurethane emulsion.

[0020] Preferably, the mass ratio of the modified polyisocyanate, the phosphate group-containing polyol, the dimethylol propionic acid, the 1,4-butanediol and the catalyst is 5.2-5.5:1:0.08-0.13:0.09-0.12:0.035-0.051.

[0021] Preferably, the modified polyisocyanate is prepared as follows:

[0022] Step A1: Add cyanuric chloride to a mixed solution of acetone and deionized water, add 4-(2-furyl)aniline, raise the temperature to 10-20°C, react for 20-40 minutes, then raise the temperature to 50-70°C, react for 2-3 hours, and complete the reaction to obtain intermediate 1;

[0023] The volume ratio of acetone to deionized water was 1:1.5.

[0024] Step A2: Add 4-maleimidephenol to toluene solvent, stir evenly, heat to 70-90°C, add intermediate 1, react for 5-7 hours, cool to 20-30°C, let stand for 50-70 minutes, filter, and dry to obtain intermediate 2;

[0025] Step A3: Add intermediate 2 and 1,5-pentane diisocyanate to a toluene solvent, stir evenly, add dibutyltin dilaurate as a catalyst, heat to 70-90°C, react for 2-4 hours, cool, and distill under low pressure to obtain a modified polyisocyanate;

[0026] By combining furan and maleimide groups, an intelligent response network is constructed to reduce the frequency of downtime maintenance during high-speed papermaking and improve paper production efficiency.

[0027] Through the triazine group and the phosphate group, the stripping agent can interact with the CaCO3 surface of the paper filler through electrostatic interaction and covalent bond. 2+ Combination, thereby enhancing the adhesion between the release agent and the substrate, ensuring the stability of continuous production of high-speed paper machines.

[0028] Preferably, the mass ratio of cyanuric chloride to 4-(2-furyl)aniline in step A1 is 1:2.4-2.6;

[0029] The mass ratio of 4-maleimide phenol to intermediate 1 in step A2 is 0.6-0.7:1;

[0030] The mass ratio of the intermediate 2, 1,5-pentane diisocyanate and dibutyltin dilaurate in step A3 is 1:0.4-0.5:0.003-0.008.

[0031] Preferably, the preparation method of the phosphate group-containing polyol is as follows:

[0032] Add polyether diol 400 to a beaker, heat to 90-100°C, dehydrate for 50-70 minutes, cool to 20-40°C, add toluene and triethylamine, stir evenly, then add phosphorus oxychloride, react for 3-5 hours, separate into layers, and distill under reduced pressure to obtain a polyol containing phosphate groups.

[0033] Preferably, the mass ratio of the polyether diol 400, toluene, triethylamine and phosphorus oxychloride is 7-8:0.9-1.1:1.8-2:1.

[0034] Beneficial effects of the present invention:

[0035] The present invention provides a modified stripping agent for papermaking and a preparation method thereof. The present invention realizes multi-dimensional optimization of the stripping agent performance through innovative design of an environmentally friendly material system and synergistic effects of dynamic functional components, combined with specific process regulation. Compared with the existing technology, this solution abandons traditional harmful ingredients and adopts a new hydrophobic structure and intelligent response network, which significantly improves the product stability and safety. At the same time, by strengthening the interface bonding ability, the stripping force is ensured to be precisely controllable and the production and maintenance costs are reduced. It is suitable for high-demand scenarios such as food packaging and high-speed paper machines, and has broad market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only for the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 The synthetic route of the modified polyisocyanate in the present invention is shown in FIG. DETAILED DESCRIPTION

[0038] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to specific embodiments.

[0039] Example 1: A method for preparing a polyol containing phosphate groups.

[0040] Add 700g of polyether diol 400 into a beaker, heat to 90℃, dehydrate for 70min, cool to 20℃, add 90g of toluene and 180g of triethylamine, stir evenly, then add 100g of phosphorus oxychloride, react for 5h, separate layers, and distill under reduced pressure to obtain a polyol containing phosphate groups.

[0041] Example 2: A method for preparing a polyol containing phosphate groups.

[0042] Add 750g of polyether diol 400 into a beaker, heat to 95°C, dehydrate for 60min, cool to 30°C, add 95g of toluene and 190g of triethylamine, stir evenly, then add 100g of phosphorus oxychloride, react for 4h, separate layers, and distill under reduced pressure to obtain a polyol containing phosphate groups.

[0043] Example 3: A method for preparing a polyol containing phosphate groups.

[0044] Add 800g of polyether diol 400 into a beaker, heat to 100℃, dehydrate for 50min, cool to 40℃, add 100g of toluene and 200g of triethylamine, stir evenly, then add 100g of phosphorus oxychloride, react for 3h, separate layers, and distill under reduced pressure to obtain a polyol containing phosphate groups.

[0045] Example 4: A method for preparing a modified polyisocyanate

[0046] S1: Add 100 g of cyanuric chloride to a mixed solution of 200 mL of acetone and 300 mL of deionized water, add 240 g of 4-(2-furyl)aniline, heat to 10°C, react for 40 min, then heat to 50°C, react for 3 h. The reaction is complete to obtain intermediate 1;

[0047] S2: Add 60 g of 4-maleimide phenol to 200 mL of toluene solvent, stir evenly, heat to 70°C, add 100 g of intermediate 1, react for 7 h, and after the reaction is complete, cool to 20°C, let stand for 70 min, filter, and dry to obtain intermediate 2;

[0048] S3: Add 100 g of intermediate 2 and 40 g of 1,5-pentane diisocyanate to 150 mL of toluene solvent, stir evenly, add 0.3 g of catalyst dibutyltin dilaurate, heat to 70 ° C, react for 4 h, cool, and distill under low pressure to obtain modified polyisocyanate.

[0049] Example 5: Preparation method of modified polyisocyanate

[0050] S1: Add 100 g of cyanuric chloride to a mixed solution of 200 mL of acetone and 300 mL of deionized water, add 250 g of 4-(2-furyl)aniline, heat to 15°C, react for 30 min, then heat to 60°C, react for 2.5 h. The reaction is complete to obtain intermediate 1;

[0051] S2: Add 65 g of 4-maleimide phenol to 200 mL of toluene solvent, stir evenly, heat to 80°C, add 100 g of intermediate 1, react for 6 h, and after the reaction is complete, cool to 25°C, let stand for 60 min, filter, and dry to obtain intermediate 2;

[0052] S3: Add 100 g of intermediate 2 and 45 g of 1,5-pentane diisocyanate into 150 mL of toluene solvent, stir evenly, add 0.5 g of catalyst dibutyltin dilaurate, heat to 80 ° C, react for 3 h, cool, and distill at low pressure to obtain modified polyisocyanate.

[0053] Example 6: Preparation method of modified polyisocyanate

[0054] S1: Add 100 g of cyanuric chloride to a mixed solution of 200 mL of acetone and 300 mL of deionized water, add 260 g of 4-(2-furyl)aniline, heat to 20°C, react for 20 min, then heat to 70°C, react for 2 h. The reaction is complete to obtain intermediate 1;

[0055] S2: Add 70 g of 4-maleimide phenol to 200 mL of toluene solvent, stir evenly, heat to 90°C, add 100 g of intermediate 1, react for 5 h, and after the reaction is complete, cool to 30°C, let stand for 50 min, filter, and dry to obtain intermediate 2;

[0056] S3: Add 100 g of intermediate 2 and 50 g of 1,5-pentane diisocyanate to 150 mL of toluene solvent, stir evenly, add 0.8 g of catalyst dibutyltin dilaurate, heat to 90 ° C, react for 2 h, cool, and distill under low pressure to obtain modified polyisocyanate.

[0057] Example 7: Preparation method of modified polyurethane emulsion

[0058] Add 52g of modified polyisocyanate and 10g of polyol containing phosphate group into a three-necked flask, heat to 80℃, react for 4h, cool to 35℃, add 0.8g of dihydroxymethylpropionic acid and 0.9g of 1,4-butanediol, heat to 90℃, react for 60min, cool to 50℃, add 0.35g of catalyst dibutyltin dilaurate, heat to 60℃ again, react for 5h, complete the reaction, cool to 30℃, neutralize with triethylamine, emulsify with deionized water, and distill under reduced pressure to obtain modified polyurethane emulsion.

[0059] Example 8: Preparation method of modified polyurethane emulsion

[0060] Add 53g of modified polyisocyanate and 10g of polyol containing phosphate group into a three-necked flask, heat to 85℃, react for 3h, cool to 40℃, add 1g of dihydroxymethylpropionic acid and 1g of 1,4-butanediol, heat to 80℃, react for 75min, cool to 40℃, add 0.4g of catalyst dibutyltin dilaurate, heat to 70℃ again, react for 4h, complete the reaction, cool to 40℃, neutralize with triethylamine, emulsify with deionized water, and distill under reduced pressure to obtain modified polyurethane emulsion.

[0061] Example 9: Preparation method of modified polyurethane emulsion

[0062] Add 55g of modified polyisocyanate and 10g of polyol containing phosphate group into a three-necked flask, heat to 90℃, react for 2h, cool to 55℃, add 1.3g of dihydroxymethylpropionic acid and 1.2g of 1,4-butanediol, heat to 70℃, react for 90min, cool to 35℃, add 0.51g of catalyst dibutyltin dilaurate, heat to 60℃, react for 5h, complete the reaction, cool to 30℃, neutralize with triethylamine, emulsify with deionized water, and distill under reduced pressure to obtain modified polyurethane emulsion.

[0063] Example 10: Preparation method of a modified stripping agent for papermaking

[0064] S1: Under a nitrogen atmosphere, 45 g of vinyl silicone oil, 2 g of vinyltrimethylsilane, and 2 g of OP-10 emulsifier were added to 100 g of deionized water, heated to 20°C, stirred for 40 min at a speed of 1800 rpm, then heated to 80°C, 0.5 g of potassium persulfate was added, and the mixture was stirred for 2 h at a speed of 600 rpm. The reaction was completed to obtain a silicone emulsion mixture;

[0065] S2: Add 50g of silicone emulsion mixture into a flask, heat to 70℃, rotate at 400rpm, add 12g of modified polyurethane emulsion, 8g of butyl acrylate, 6g of polyamide-amine dendrimer, 1g of octadecyl acrylate and 1g of azobisisobutyronitrile, react for 5h, and after the reaction is complete, cool to 50℃, add glycidyl methacrylate, stir and react for 70min, rotate at 150rpm, add 10wt% citric acid solution, adjust the pH to 6.5-7, filter, and obtain a modified stripping agent.

[0066] Example 11: Preparation method of a modified stripping agent for papermaking

[0067] S1: Under a nitrogen atmosphere, 50 g of vinyl silicone oil, 3 g of vinyltrimethylsilane, and 3 g of OP-10 emulsifier were added to 100 g of deionized water, heated to 25°C, stirred for 30 min at a speed of 2000 rpm, then heated to 75°C, 0.8 g of potassium persulfate was added, and the mixture was stirred for 2.5 h at a speed of 500 rpm. The reaction was completed to obtain a silicone emulsion mixture;

[0068] S2: Add 55g of silicone emulsion mixture into a flask, heat to 75°C, rotate at 300rpm, add 13g of modified polyurethane emulsion, 9g of butyl acrylate, 2g of polyamide-amine dendrimer, 7g of octadecyl acrylate and 1.2g of azobisisobutyronitrile, react for 4h, and after the reaction is complete, cool to 55°C, add 2g of glycidyl methacrylate, stir and react for 60min, rotate at 200rpm, add 10wt% citric acid solution, adjust the pH to 6.5-7, filter, and obtain a modified stripping agent.

[0069] Example 12: Preparation method of a modified stripping agent for papermaking

[0070] S1: Under a nitrogen atmosphere, 55 g of vinyl silicone oil, 4 g of vinyltrimethylsilane, and 4 g of OP-10 emulsifier were added to 100 g of deionized water, heated to 30°C, stirred for 20 min at 2200 rpm, then heated to 70°C, potassium persulfate was added, and the mixture was stirred for 3 h at 400 rpm. The reaction was completed to obtain a silicone emulsion mixture;

[0071] S2: Add 60g of silicone emulsion mixture into a flask, heat to 80℃, rotate at 200rpm, add 15g of modified polyurethane emulsion, 10g of butyl acrylate, 3g of polyamide-amine dendrimer, 8g of octadecyl acrylate and 1.5g of azobisisobutyronitrile, react for 5h, and after the reaction is complete, cool to 50℃, add 3g of glycidyl methacrylate, stir and react for 70min, rotate at 150rpm, add 10wt% citric acid solution, adjust the pH to 6.5-7, filter, and obtain a modified stripping agent.

[0072] Comparative Example 1:

[0073] Compared with Example 10, this comparative example does not add polyamide-amine dendrimers during the preparation of the modified stripping agent. The remaining steps and parameters are the same and will not be repeated in this comparative example. Finally, a modified stripping agent is obtained.

[0074] Comparative Example 2:

[0075] Compared with Example 10, this comparative example only replaces "vinyl silicone oil and vinyltrimethylsilane" with "equal mass of perfluorooctanoic acid", and the remaining steps and parameters are the same, which will not be repeated in this comparative example, and finally a modified stripping agent is obtained.

[0076] Comparative Example 3:

[0077] Compared with Example 10, this comparative example only replaces the "polyol containing phosphate group" with "polyether diol 400", and the remaining steps and parameters are the same, which will not be repeated in this comparative example, and finally a modified stripping agent is obtained.

[0078] Comparative Example 4:

[0079] Compared with Example 10, this comparative example only replaces "potassium persulfate" with "ammonium persulfate", and the remaining steps and parameters are the same, which will not be repeated in this comparative example, and finally a modified stripping agent is obtained.

[0080] Comparative Example 5:

[0081] Compared with Example 10, this comparative example only replaces "4-maleimidephenol" with "4-aminophenol", and the remaining steps and parameters are the same, which will not be repeated in this comparative example, and finally a modified stripping agent is obtained.

[0082] Comparative Example 6:

[0083] Compared with Example 10, this comparative example only increases the amount of butyl acrylate to 15 g during the preparation of the modified stripping agent. The remaining steps and parameters are the same and will not be repeated in this comparative example. Finally, a modified stripping agent is obtained.

[0084] Experimental sample preparation

[0085] 100 g of ethanol and 50 g of propylene glycol methyl ether were added to 700 g of deionized water and stirred evenly. The modified stripping agents prepared in Examples 10-12 and Comparative Examples 1-6 were added respectively at a rotation speed of 800-1000 rpm. The pH was adjusted to 6.5-7.0 with 10% wt citric acid solution to obtain experimental samples.

[0086] Performance testing:

[0087] Peel force test

[0088] Refer to GB / T2792-2014 test standard and use MTS-Criterion universal material testing machine;

[0089] 1. Take the experimental samples of Examples 10-12 and Comparative Examples 1-6 respectively, and evenly apply them on 80g / m 2 Place the coated paper and CaCO3-filled paper in a constant temperature and humidity chamber at 25°C ± 1°C and 50% RH ± 5% for curing for 24 hours;

[0090] 2. Take it out and fix it on the peeling fixture. The peeling angle is 180° and the stretching speed is 300 mm / min. The average peeling force of the stable section is measured in N / m.

[0091] Wear resistance test

[0092] Refer to ASTM D4060-19 test standard and use Taber-5135 abrasion tester;

[0093] The experimental samples of Examples 10-12 and Comparative Examples 1-6 were coated on paper, cut into discs with a diameter of 100 mm, and fixed on the abrasion machine turntable. The load was 500 g / wheel, and the abrasion cycle was 100 revolutions. The mass loss of the sample after abrasion and the visual surface wear grade were recorded, and the wear resistance index was calculated:

[0094]

[0095] Contact angle test

[0096] Refer to ISO 19403-2:2017 test standard and use DSA25 contact angle meter;

[0097] The experimental samples of Examples 10-12 and Comparative Examples 1-6 were respectively coated on paper, and the paper was cut into 20 mm × 20 mm pieces. 3 μL of deionized water was added. The droplet morphology was recorded using a high-speed camera, and the software automatically calculated the contact angle in degrees. Five different positions of each sample were measured, and the average value was taken.

[0098] Table 1 Test data of Examples 10-12 and Comparative Examples 1-6

[0099]

[0100] Thermal stability test

[0101] Refer to GB / T 1735-2009 test standard, using UF110 high temperature oven and Q500 thermogravimetric analyzer;

[0102] 1. Static heat aging: Take the experimental samples of Examples 10-12 and Comparative Examples 1-6 and apply them on the samples respectively. Place them in an oven and heat them to 100℃±2℃ for 24 hours. Observe whether the coatings are cracked, peeled or discolored.

[0103] 2. Dynamic Thermal Analysis: 10 mg of each dried experimental sample from Examples 10-12 and Comparative Examples 1-6 was placed in a crucible. Under a nitrogen atmosphere, the temperature was raised at a rate of 10°C / min over a temperature range of 30-600°C. The thermal decomposition temperature (Td, the temperature corresponding to 5% weight loss) and the residual carbon rate were recorded.

[0104] Table 2 Thermal stability data of Examples 10-12 and Comparative Examples 1-6

[0105]

[0106] Environmental testing

[0107] According to the GB18582-2020 test standard, a UNITY2 thermal desorber and an Agilent -7890B gas chromatograph were used. The chromatographic column was a DB-5 capillary column, 30m×0.25mm×0.25μm, the injection port temperature was 250℃, and the detector temperature was 280℃.

[0108] 1. Take 5 g of each of the experimental samples of Examples 10-12 and Comparative Examples 1-6, place them in a clean aluminum foil weighing dish, place in a nitrogen atmosphere at a flow rate of 50 mL / min, place in an oven, heat to 105°C, bake for 1 hour, and carry the volatiles into the adsorption tube;

[0109] 2. Connect the adsorption tube to the thermal desorber, set the desorption temperature to 280℃, the desorption time to 10min, and introduce the desorbed gas directly into the GC inlet, initially at 50℃ for 2min, then increase the temperature to 250℃ at a rate of 10℃ / min and hold for 5min;

[0110] 3. VOC content formula:

[0111]

[0112] Where: m0: mass of blank adsorption tube (g);

[0113] m2: total mass of adsorption tube and volatiles (g);

[0114] m1: initial mass of the sample (g).

[0115] Table 3 Thermal stability data of Examples 10-12 and Comparative Examples 1-6

[0116]

[0117] Dynamic response capability testing

[0118] Take 5 mL of each of Examples 10-12 and Comparative Examples 1-6, apply the sample evenly on the lower plate, slowly close the clamp to a gap of 1 mm, start the DHR-3 rotational rheometer, set the initial temperature to 25 ° C, keep the temperature constant for 5 minutes, increase the temperature to 80 ° C at 2 ° C / min, keep it for 5 minutes, cool it down to 25 ° C at 2 ° C / min, keep it for 5 minutes; the shear rate is constant for 100 seconds -1 , data acquisition frequency 1Hz;

[0119] By integrating the viscosity difference area of ​​the heating and cooling curves, the area (unit: Pa·s·℃) is calculated. The viscosity recovery rate is calculated as follows: (η 峰值 Maximum viscosity at 80°C)

[0120]

[0121] Table 4 Dynamic response capability test data of Examples 10-12 and Comparative Examples 1-6

[0122]

[0123] Data Analysis:

[0124] As can be seen from Tables 1-4, the modified stripping agent prepared by the present invention has better interfacial bonding strength, wear resistance, hydrophobicity, thermal stability, environmental protection and dynamic response ability;

[0125] In Comparative Example 1, since no polyamide-amine dendrimers were added, the surface structure was loose, the wear resistance was reduced, and the paper filler could not be effectively bonded, resulting in weakened adhesion. The thermal stability and dynamic response capabilities were also reduced due to the lack of a cross-linked network. This is because the polyamide-amine dendrimers can produce a synergistic effect with the long-chain alkyl group, thereby improving the hydrophobicity and interfacial bonding strength of the stripper by constructing a rough structure.

[0126] In Comparative Example 2, since the vinyl silicone oil and vinyltrimethylsilane are replaced with perfluorooctanoic acid of equal mass, the contact angle is increased, but the VOC content increases dramatically. The reason is that perfluorooctanoic acid contains a large number of CF bonds, which are superhydrophobic. Although the contact angle is improved by the superhydrophobicity of the CF bond, the carboxylic acid group of perfluorooctanoic acid undergoes decarboxylation reaction at high temperature, releasing CO2 and fluorinated fragments, resulting in a sharp increase in VOC content. At the same time, perfluorooctanoic acid itself has been listed as a persistent organic pollutant. In addition, its self-repair mechanism decreases. The reason is that the bond energy of the CF bond in perfluorooctanoic acid is high. Although it has a certain chemical inertness, it also enhances the rigidity of its molecular chain. The electronegativity of the fluorine atom is extremely large, which makes the CF bond highly polar. However, the intermolecular force is mainly van der Waals force, which makes it difficult for the perfluoro compound to form effective compatibility with other polar components, destroying the flexibility of the dynamic network, and the rigid molecular chain is difficult to undergo conformational changes when subjected to force, which limits the deformation ability of the material under mechanical stress, resulting in a decrease in the dynamic response recovery rate.

[0127] Comparative Example 3 replaces the polyol containing phosphate group with polyether diol 400, which results in the loss of adhesion between the stripper and the substrate, increased peeling force, easy peeling of the coating, and failure to form an effective hydrophobic structure. The reason is that the negative charge of the phosphate group can directly attract Ca 2+, forming ion pairs, thereby providing initial interfacial bonding force, allowing the stripper to quickly adsorb on the filler surface. At the same time, the long chain structure of the polyol can enable the phosphate group to form multiple anchor points on the filler surface, further improving the bonding stability. In addition, the stable bonding can prevent the stripper from falling off under mechanical stress, maintaining the integrity of the coating, thereby optimizing the wear resistance index, and the phosphate group and Ca 2+ The bond energy of the Ca-OP bond is high and is not easily broken at high temperatures, which leads to a higher thermal decomposition temperature of the stripping agent containing phosphate groups;

[0128] In Comparative Example 4, since potassium persulfate is replaced by ammonium persulfate, the crosslinking density is insufficient, which affects the thermal stability and dynamic response ability. At the same time, the residual by-products increase VOC emissions. The reason is that the decomposition temperature of potassium persulfate is higher than that of ammonium persulfate, and potassium persulfate as an initiator has a moderate free radical release rate, which is conducive to controlling the polymerization process, avoiding local overreaction, and ensuring a uniform crosslinked network. The high crosslinking network can improve its thermal stability and mechanical strength. In addition, the decomposition product of potassium persulfate is a water-soluble inorganic salt, which is easy to clean and has a small residual amount, so the VOC emission is low, while the decomposition product of ammonium persulfate contains NH + 4. It will react with carboxylic acid groups to generate ammonia, which will lead to an increase in VOC content;

[0129] In Comparative Example 5, since 4-maleimide aniline is replaced by 4-aminophenol, the dynamic network is lost, resulting in decreased interfacial bonding strength, poor thermal stability, and inability to respond to mechanical stress. The reason is that the maleimide group and the furan group form a six-membered ring structure through the Diels-Alder reaction. When the temperature is below 100°C, a stable ring structure is formed. When the temperature is above 120°C, the ring structure dissociates and returns to maleimide and furan groups. This reversibility gives the material dynamic bonding ability, allowing it to self-repair under mechanical damage or thermal stimulation. The dynamic bonds form a three-dimensional network through chemical cross-linking, which can enhance the bonding strength between the stripper and the paper filler. Moreover, at high temperatures, the dynamic bonds absorb energy by decomposition, which can delay the decomposition of the material, thereby reducing the thermal decomposition of the stripper and improving its utilization rate.

[0130] In Comparative Example 6, excessive butyl acrylate resulted in uneven crosslinking density, reduced surface roughness, and an imbalance between flexibility and rigidity, affecting wear resistance and peel force control. This is because butyl acrylate, as a flexible monomer, participates in the formation of a crosslinked network through free radical polymerization. Its long alkyl chain imparts flexibility and adhesion to the material. In the formulation, butyl acrylate maintains a balance with octadecyl acrylate and the crosslinker glycidyl methacrylate, forming a uniform three-dimensional network. While the flexible segments of butyl acrylate increase material fluidity, they also smooth the surface during curing, reducing the formation of rough structures on the surface by polyamide-amine dendrimers. Excess butyl acrylate also interferes with the aggregation of octadecyl acrylate, hindering the formation of rough structures and further reducing surface roughness. Furthermore, the -COO- bonds of the excess butyl acrylate form hydrogen bonds with the CaCO3 filler paper, enhancing peel resistance. Furthermore, the excessive use of butyl acrylate leads to uneven crosslinking, reducing the material's cohesive strength, resulting in cohesive failure in some areas during peeling, further increasing the actual peel force, resulting in an increased peel force.

[0131] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention is limited to these examples. Within the scope of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

[0132] The present invention is intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A modified stripping agent for papermaking, characterized in that: The invention is prepared from the following raw materials in parts by weight: 45-55 parts of vinyl silicone oil, 2-4 parts of vinyltrimethylsilane, 2-4 parts of OP-10 emulsifier, 10-15 parts of modified polyurethane emulsion, 8-12 parts of butyl acrylate, 6-8 parts of octadecyl acrylate, 1-3 parts of polyamide-amine dendrimer, 0.5-1 part of potassium persulfate, 1-1.5 parts of azobisisobutyronitrile, and 1-3 parts of glycidyl methacrylate. The modified polyurethane emulsion is prepared from modified polyisocyanate and polyol containing phosphate groups; The modified polyisocyanate is prepared as follows: Step A1: Add cyanuric chloride to a mixed solution of acetone and deionized water, add 4-(2-furyl)aniline, raise the temperature to 10-20°C, react for 20-40 minutes, then raise the temperature to 50-70°C, react for 2-3 hours, and complete the reaction to obtain intermediate 1; Step A2: Add 4-maleimidephenol to toluene solvent, stir evenly, heat to 70-90°C, add intermediate 1, react for 5-7 hours, cool to 20-30°C, let stand for 50-70 minutes, filter, and dry to obtain intermediate 2; Step A3: Add intermediate 2 and 1,5-pentane diisocyanate to a toluene solvent, stir evenly, add dibutyltin dilaurate as a catalyst, heat to 70-90°C, react for 2-4 hours, cool, and distill under low pressure to obtain a modified polyisocyanate; The mass ratio of cyanuric chloride to 4-(2-furyl)aniline in step A1 is 1:2.4-2.6; The mass ratio of 4-maleimide phenol to intermediate 1 in step A2 is 0.6-0.7:1; The mass ratio of the intermediate 2, 1,5-pentane diisocyanate and dibutyltin dilaurate in step A3 is 1:0.4-0.5:0.003-0.008; The preparation method of the modified stripping agent for papermaking is as follows: Step S1: Under a nitrogen atmosphere, vinyl silicone oil, vinyl trimethylsilane, and OP-10 emulsifier are added to deionized water, the temperature is raised to 20-30°C, and stirred for 20-40 minutes at a rotation speed of 1800-2200 rpm. The temperature is then raised to 70-80°C, potassium persulfate is added, and the mixture is stirred for 2-3 hours at a rotation speed of 400-600 rpm. The reaction is completed to obtain a silicone emulsion mixture; Step S2: Add the silicone emulsion mixture to a flask, raise the temperature to 70-80°C, rotate at 200-400 rpm, add modified polyurethane emulsion, butyl acrylate, polyamide-amine dendrimer, octadecyl acrylate and azobisisobutyronitrile, react for 3-5 hours, cool to 50-60°C, add glycidyl methacrylate, stir and react for 50-70 minutes, rotate at 150-250 rpm, adjust the pH to 6.5-7, filter, and obtain a modified stripping agent.

2. A method for preparing a modified stripping agent for papermaking according to claim 1, characterized in that: The following steps are involved: Step S1: Under a nitrogen atmosphere, vinyl silicone oil, vinyl trimethylsilane, and OP-10 emulsifier are added to deionized water, the temperature is raised to 20-30°C, and stirred for 20-40 minutes at a rotation speed of 1800-2200 rpm. The temperature is then raised to 70-80°C, potassium persulfate is added, and the mixture is stirred for 2-3 hours at a rotation speed of 400-600 rpm. The reaction is completed to obtain a silicone emulsion mixture; Step S2: Add the silicone emulsion mixture to a flask, raise the temperature to 70-80°C, rotate at 200-400 rpm, add modified polyurethane emulsion, butyl acrylate, polyamide-amine dendrimer, octadecyl acrylate and azobisisobutyronitrile, react for 3-5 hours, cool to 50-60°C, add glycidyl methacrylate, stir and react for 50-70 minutes, rotate at 150-250 rpm, adjust the pH to 6.5-7, filter, and obtain a modified stripping agent.

3. The method for preparing a modified stripping agent for papermaking according to claim 2, wherein: In step S2, the mass ratio of the silicone emulsion mixture, modified polyurethane emulsion, butyl acrylate, polyamide-amine dendrimer, octadecyl acrylate, azobisisobutyronitrile and glycidyl methacrylate is 50-60:12-15:8-10:1-3:6-8:1-1.5:1-3.

4. The method for preparing a modified stripping agent for papermaking according to claim 2, wherein: The modified polyurethane emulsion is prepared as follows: Add modified polyisocyanate and phosphate group-containing polyol into a three-necked flask, heat to 80-90°C, react for 2-4h, cool to 35-55°C, add dimethylol propionic acid and 1,4-butanediol, heat to 70-90°C, react for 60-90min, cool to 35-50°C, add catalyst dibutyltin dilaurate, heat to 60-80°C again, react for 3-5h, complete the reaction, cool to 30-50°C, neutralize with triethylamine, emulsify with deionized water, and distill under reduced pressure to obtain a modified polyurethane emulsion.

5. The method for preparing a modified stripping agent for papermaking according to claim 4, wherein: The mass ratio of the modified polyisocyanate, the polyol containing a phosphate group, the dimethylol propionic acid, the 1,4-butanediol and the catalyst is 5.2-5.5:1:0.08-0.13:0.09-0.12:0.035-0.

051.

6. The method for preparing a modified stripping agent for papermaking according to claim 4, wherein: The preparation method of the phosphate group-containing polyol is as follows: Add polyether diol 400 to a beaker, heat to 90-100°C, dehydrate for 50-70 minutes, cool to 20-40°C, add toluene and triethylamine, stir evenly, then add phosphorus oxychloride, react for 3-5 hours, separate into layers, and distill under reduced pressure to obtain a polyol containing phosphate groups.

7. The method for preparing a modified stripping agent for papermaking according to claim 6, wherein: The mass ratio of the polyether glycol 400, toluene, triethylamine and phosphorus oxychloride is 7-8: 0.9-1.1:1.8-2:1。

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