High-strength, compression-resistant, balanced paper and method for making same

Abstract

The application relates to the technical field of balanced paper, in particular to high-strength compression-resistant balanced paper and a preparation method thereof. The preparation method comprises the following steps: S1: starch is subjected to viscosity reduction treatment, then the starch is grafted with a flame retardant to obtain modified starch; then the modified starch, paper pulp fiber, sodium alginate and deionized water are uniformly mixed to obtain paper pulp liquid; finally, high-strength base paper is obtained through sheet forming, pressing, drying and cutting; S2: chitosan is sequentially reacted with glycidyltrimethylammonium chloride, allyl hydroxyethyl ether and acrylamide and glycidyl acrylate to obtain reinforced resin liquid; then formaldehyde, melamine, the reinforced resin liquid, propylene glycol and deionized water are uniformly mixed to obtain melamine impregnation liquid, which is prepared for use; S3: a curing agent, a release agent and a penetrating agent are added to the melamine impregnation liquid, the high-strength base paper is immersed in the mixture, and the high-strength compression-resistant balanced paper is obtained through twice repeated immersion and drying.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of balance paper, in particular to a high-strength compression-resistant balance paper and a preparation method thereof. BACKGROUND

[0002] Balance paper is a kind of special paper with high quality, which is used for balancing the stress of wood floor after being impregnated with melamine resin and treated at high temperature and high pressure. The main function of balance paper is to stabilize the size of wood floor and prevent it from warping and deforming, so as to ensure the flatness of wood floor. In addition, balance paper can effectively prevent moisture from penetrating from the back of wood floor and improve the moisture resistance of wood floor.

[0003] However, the melamine resin is brittle after curing, which is not conducive to the protection of wood floor. Therefore, the present application prepares a high-strength compression-resistant balance paper by considering the original paper and the melamine impregnating solution. SUMMARY

[0004] The present application aims to provide a high-strength compression-resistant balance paper and a preparation method thereof to solve the problems in the background.

[0005] In order to solve the above technical problems, the present application provides the following technical scheme:

[0006] A preparation method of a high-strength compression-resistant balance paper, comprising the following steps:

[0007] S1: preparing a high-strength original paper:

[0008] S11: dispersing starch into deionized water at 40-50℃ to prepare a 40-50wt% starch suspension; then adding hydrochloric acid solution to adjust the pH to 2-4, stirring for 1-3h, then adding sodium hydroxide solution to adjust the pH to neutral, and finally filtering, washing, drying, crushing, and sieving to obtain a viscosity-reducing starch;

[0009] S12: (1) dispersing trichlorophosphazene and tetrabutylammonium bromide into ten times the weight of acetone, then heating to 60-80℃, and adding 2-hydroxy-5-amino pyridine, refluxing for 12-24h, stopping the reaction, and finally filtering, washing, and drying to obtain product A; (2) dispersing carboxymethyl chitosan into ten times the weight of 2-4v / v% dilute hydrochloric acid solution, then adding product A, condensing agent, and acylation catalyst, stirring at room temperature for 6-24h, stopping the reaction, then adding sodium hydroxide solution to adjust the pH to neutral, and finally filtering, washing, and drying to obtain a flame retardant;

[0010] S13: Disperse the viscosity-reducing starch into deionized water to prepare a 30-50 wt% viscosity-reducing starch suspension; then add 10-20 wt% acetic acid solution to adjust the pH to 2-4, heat to 60-80°C, and add the flame retardant thereto, reflux for 6-12 h, end the reaction, add sodium hydroxide solution to adjust the pH to neutral, and finally filter, wash, dry, crush, and sieve to obtain the modified starch;

[0011] S14: Disperse the paper pulp fibers into deionized water to prepare a 5-10 wt% paper pulp fiber suspension; then add the modified starch and sodium alginate, mix well, and obtain the paper pulp liquid; and finally sheet, press, dry, and cut to obtain the high-strength base paper.

[0012] S2: Prepare the melamine impregnation solution:

[0013] S21: (1) Disperse the chitosan into isopropyl alcohol to prepare a 5-10 wt% chitosan suspension, then heat to 70-80°C, slowly add the glycidyltrimethylammonium chloride thereto, react for 2-6 h, end the reaction, add anhydrous ethanol and stand for 1-2 h, precipitate, and finally filter, wash, and dry to obtain the modified chitosan I; (2) Mix the modified chitosan I and allyl hydroxyethyl ether in a reaction vessel, add the benzenesulfonic acid and hydroquinone, stir at 130-150°C for 10-30 min, end the reaction, and finally separate, wash, and dry to obtain the modified chitosan II; (3) Mix the modified chitosan II, acrylamide, and glycidyl acrylate in a reaction vessel, add the dibenzoyl peroxide, stir at 110-130°C for 1-3 h, end the reaction, and obtain the reinforcing resin solution;

[0014] S22: (1) Mix the formaldehyde and deionized water, and adjust the pH of the mixed solution to 8-10 to obtain the mixed solution I; (2) Add the melamine, reinforcing resin solution, and propylene glycol to the mixed solution I, heat to 80-90°C, stir for 1-2 h, then cool to room temperature, and obtain the melamine impregnation solution, ready for use;

[0015] S3: Add the curing agent, release agent, and penetrating agent to the melamine impregnation solution, mix well, then immerse the high-strength base paper in the solution, repeat the immersion and drying twice, and obtain the high-strength compression-resistant balanced paper.

[0016] Further, the starch includes but is not limited to any one of corn starch, pea starch, sweet potato starch, and sorghum starch.

[0017] Further, the molar ratio of the melamine phosphazene and 2-hydroxy-5-aminopyridine is 1:6.

[0018] Further, the tetrabutyl ammonium bromide is added in an amount of 3-5% of the mass of the trichloro phosphazene.

[0019] Further, the mass ratio of the carboxymethyl chitosan, the product A, the condensing agent, and the acylation catalyst is 1:(1-1.5):(0.01-0.02):(0.01-0.02).

[0020] Further, the condensing agent includes but is not limited to any one of dicyclohexyl carbodiimide, diisopropyl carbodiimide, and 1-(3-dimethyl aminopropyl)-3-ethyl carbodiimide.

[0021] Further, the acylation catalyst includes but is not limited to any one of 4-N,N-dimethyl pyridine and 1-hydroxy benzotriazole.

[0022] Further, the mass ratio of the viscosity-reducing starch and the flame retardant is 10:(1-2).

[0023] Further, the mass ratio of the pulp fiber, the modified starch, and the sodium alginate is 10:(0.5-1):2.

[0024] Further, the amount of the sheet is 60-80 g / m 2 .

[0025] Further, the mass ratio of the chitosan and the glycidyltrimethylammonium chloride is 1:(4-5).

[0026] Further, the mass ratio of the modified chitosan I, the allyl hydroxyethyl ether, the benzene sulfonic acid, and the hydroquinone is 1:(1-3):(0.2-0.5):(0.01-0.03).

[0027] Further, the mass ratio of the modified chitosan II, the acrylamide, the glycidyl acrylate, and the dibenzoyl peroxide is (1-2):10:5:(0.05-0.1).

[0028] Further, the melamine impregnation solution includes the following components: 100-150 parts of melamine, 150-250 parts of formaldehyde, 50-80 parts of enhanced resin liquid, 5-15 parts of propylene glycol, and 80-150 parts of deionized water by weight.

[0029] Further, the curing agent is TN-712, and is added in an amount of 4-5% of the mass of the melamine.

[0030] Further, the release agent is purchased from Shandong Defeng Polyurethane (Release Agent) Group Co., Ltd., specifically an aliphatic ethoxylated derivative, model DF-9727, and is added in an amount of 2-3% of the mass of the melamine.

[0031] Further, the penetrating agent model is TN-737, and the added amount is 2-3% of the mass of melamine.

[0032] Starch is a substance containing rich polar hydroxyl groups, which can form hydrogen bonds with the hydroxyl groups on the surface of pulp fibers, and the combination is more firm than the combination of fibers and fibers, so that the strength of the base paper can be enhanced. However, if it is ordinary starch, the viscosity of the suspension is large, which will result in that the viscosity of the starch slurry obtained by subsequent modification is also large (the flowability of the slurry is poor), which is not conducive to uniform dispersion of the pulp fibers, and finally affects the performance of the high-strength base paper prepared. Therefore, in the scheme, the starch is first subjected to acidolysis and viscosity reduction treatment, and then reacted with trichlorophosphazene and 2-hydroxy-5-aminopyridine and carboxymethyl chitosan to prepare a flame retardant grafted and prepare modified starch; the modified starch can be uniformly dispersed in the pulp slurry, and because it is grafted with the flame retardant (containing rich N, P elements and chitosan structure), the high-strength base paper prepared also has certain flame retardant and antibacterial effects, and the board can be better protected subsequently. In addition, considering that sodium alginate has the characteristics of antioxidant, antibacterial and thickening, it can improve the strength and other performances of the base paper together with the modified starch, so the scheme further adds sodium alginate to modify the base paper together with the modified starch, and finally a high-strength base paper with flame retardant, antibacterial and non-yellowing properties is prepared.

[0033] In the scheme, the chitosan is further modified, first reacted with glycidyltrimethylammonium chloride to prepare quaternized chitosan (modified chitosan I); then etherification reaction is carried out with allyl hydroxyethyl ether to introduce unsaturated bonds to obtain modified chitosan II; and finally polycondensation is carried out with acrylamide and glycidyl acrylate to obtain a reinforcing resin solution. The reinforcing resin solution is actually a polyacrylate, which can crosslink with melamine resin, thereby improving the toughness of the melamine resin and improving the compression resistance of the balanced paper. In addition, after impregnation and curing, the hydrophobicity of the balanced paper is enhanced, and due to the presence of quaternized chitosan structure in the reinforcing resin solution, the balanced paper has excellent antibacterial property (which can effectively prevent the wood board from mildewing) and excellent antistatic property (if the antistatic property is poor, dust is easily attached, which affects the subsequent lamination with the wood board and cannot effectively protect the wood board).

[0034] Compared with the prior art, the beneficial effects achieved by the present application are:

[0035] (1) The strength of the base paper is enhanced, and the base paper also has flame retardant, antibacterial and other properties by modifying the starch and adding sodium alginate together with the modified starch to modify the base paper.

[0036] (2) Since the traditional melamine impregnating solution is easy to be brittle after curing, the enhanced resin solution is added in the scheme to modify it, which can significantly improve the toughness of the melamine resin, and then the mechanical properties of the balanced paper are improved;

[0037] (3) Through the modification design of the base paper and the impregnating solution, the impregnating solution has better wettability for the base paper, and finally a high-strength compression-resistant balanced paper is obtained, which also has the properties of flame retardant, antibacterial and hydrophobic, and can more effectively protect the wood board. DETAILED DESCRIPTION

[0038] The following is a preferred embodiment of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. For ordinary skilled in the art, all other embodiments obtained without creative labor under the premise of not departing from the principles of the embodiments of the present application, belong to the scope of protection of the present application.

[0039] Embodiment 1: A preparation method of a high-strength compression-resistant balanced paper:

[0040] S1: Preparation of high-strength base paper:

[0041] S11: Disperse 150 parts of corn starch into deionized water at 45℃ to prepare a 45wt% starch suspension; then add hydrochloric acid solution to adjust the pH to 2.5, stir for 2h, then add 5wt% sodium hydroxide solution to adjust the pH to neutral, and finally filter, wash, dry, crush, and sieve to obtain a viscosity-reducing starch;

[0042] S12: (1) Disperse 7 parts of trichlorophosphazene and 0.29 parts of tetrabutylammonium bromide into 73 parts of acetone, then heat to 70℃, and add 13.2 parts of 2-hydroxy-5-aminopyridine, reflux for 15h, and then filter, wash, and dry to obtain product A; (2) Disperse 10 parts of carboxymethyl chitosan into 100 parts of 3v / v% dilute hydrochloric acid solution, then add 13 parts of product A, 0.15 parts of dicyclohexyl carbodiimide, and 0.15 parts of 4-N,N-dimethylpyridine, and stir at room temperature for 18h, then adjust the pH to neutral with 5wt% sodium hydroxide solution, and finally filter, wash, and dry to obtain a flame retardant;

[0043] S13: 100 parts of viscosity-reducing starch is dispersed in deionized water to prepare a 40wt% viscosity-reducing starch suspension; then 15wt% acetic acid solution is added to adjust the pH to 2.5, the temperature is raised to 70°C, and 15 parts of flame retardant is added, and refluxed for 8h, the reaction is stopped, 5wt% sodium hydroxide solution is added to adjust the pH to neutral, and finally filtered, washed, dried, crushed, and sieved to obtain modified starch;

[0044] S14: 1000 parts of paper pulp fiber is dispersed in deionized water to prepare a 8wt% paper pulp fiber suspension; then 75 parts of modified starch and 200 parts of sodium alginate are added and stirred to obtain a paper pulp solution; finally, high-strength base paper is obtained by sheet forming (sheet forming amount 70g / m 2 ), pressing, and drying;

[0045] S2: Preparation of melamine impregnation solution:

[0046] S21: (1) 5 parts of chitosan is dispersed in isopropyl alcohol to prepare a 5wt% chitosan suspension, then the temperature is raised to 75°C, and 22 parts of glycidyltrimethylammonium chloride is slowly added, and reacted for 5h, the reaction is stopped, 40 parts of anhydrous ethanol is added and left for 2h, the precipitate is separated, and finally filtered, washed, and dried to obtain modified chitosan I; (2) 10 parts of modified chitosan I and 20 parts of allyl hydroxyethyl ether are added to a reaction vessel and stirred to mix uniformly, then 3 parts of benzenesulfonic acid and 0.2 parts of hydroquinone are added, and stirred at 140°C for 20min, the reaction is stopped, and finally separated, washed, and dried to obtain modified chitosan II; (3) 8 parts of modified chitosan II, 50 parts of acrylamide, and 25 parts of glycidyl acrylate are added to a reaction vessel and stirred to mix uniformly, then 0.35 parts of dibenzoyl peroxide is added, and stirred at 120°C for 2h, the reaction is stopped, and an enhanced resin solution is obtained;

[0047] S22: (1) 200 parts of formaldehyde and 120 parts of deionized water are mixed, and the pH of the mixed solution is adjusted to 9 to obtain mixed solution I; (2) 120 parts of melamine, 65 parts of enhanced resin solution, and 10 parts of propylene glycol are added to mixed solution I, and the temperature is raised to 80°C, and stirred for 2h, then cooled to room temperature to obtain melamine impregnation solution, which is ready for use;

[0048] S3: 5.4 parts of TN-712 type curing agent, 3 parts of DF-9727 type release agent, and 3 parts of TN-737 type penetrating agent are added to the melamine impregnation solution, and stirred to mix uniformly, then the high-strength base paper is immersed in the melamine impregnation solution, and dried after two repeated immersions to obtain high-strength compression-resistant balanced paper.

[0049] Example 2: A method for preparing high-strength compression-resistant balanced paper:

[0050] S1: preparing high-strength base paper:

[0051] S11: dispersing 150 parts of corn starch into deionized water to prepare a 45wt% starch suspension; then adding hydrochloric acid solution to adjust the pH to 2.5, stirring for 2h, then adding 5wt% sodium hydroxide solution to adjust the pH to neutral, and finally filtering, washing, drying, crushing, and sieving to obtain a viscosity-reducing starch;

[0052] S12: (1) dispersing 7 parts of trimeric phosphorus chloride into 73 parts of acetone, then heating to 70℃, and adding 13.2 parts of 2-hydroxy-5-amino pyridine, refluxing for 12h, and finally filtering, washing, and drying to obtain product A; (2) dispersing 10 parts of carboxymethyl chitosan into 100 parts of 3v / v% dilute hydrochloric acid solution, then adding 10 parts of product A, 0.15 parts of condensing agent, 0.15 parts of dicyclohexyl carbodiimide, and 0.15 parts of 4-N,N-dimethyl pyridine, adjusting the pH to neutral with 5wt% sodium hydroxide solution, and finally filtering, washing, and drying to obtain a flame retardant;

[0053] S13: dispersing 100 parts of viscosity-reducing starch into deionized water to prepare a 40wt% viscosity-reducing starch suspension; then adding 15wt% acetic acid solution to adjust the pH to 2.5, heating to 70℃, and adding 10 parts of flame retardant, refluxing for 6h, adjusting the pH to neutral with 5wt% sodium hydroxide solution, and finally filtering, washing, drying, crushing, and sieving to obtain modified starch;

[0054] S14: dispersing 1000 parts of paper pulp fiber into deionized water to prepare an 8wt% paper pulp fiber suspension; then adding 50 parts of modified starch and 200 parts of sodium alginate, stirring to mix uniformly, and finally sheeting (sheeting amount 70g / m 2 ), pressing, and drying to obtain high-strength base paper;

[0055] S2: preparing melamine impregnation solution:

[0056] S21: (1) Disperse 5 parts of chitosan in isopropanol to prepare a 5wt% chitosan suspension. Then heat to 75°C and slowly add 20 parts of glycidyl trimethylammonium chloride. React for 5 hours, then stop the reaction. Add 40 parts of anhydrous ethanol and let stand for 2 hours to precipitate. Finally, filter, wash and dry to obtain modified chitosan I; (2) Add 10 parts of modified chitosan I and 10 parts of allyl hydroxyethyl ether to the reaction vessel and mix thoroughly. After mixing, add 3 parts of benzenesulfonic acid and 0.2 parts of hydroquinone, stir at 140°C for 20 min, stop the reaction, and finally separate, wash and dry to obtain modified chitosan II; (3) Add 5 parts of modified chitosan II, 50 parts of acrylamide and 25 parts of glycidyl acrylate to the reaction vessel and mix evenly, then add 0.35 parts of benzoyl peroxide, stir at 120°C for 2 h, stop the reaction and obtain the reinforced resin liquid;

[0057] S22: (1) Mix 200 parts of formaldehyde and 120 parts of deionized water, and adjust the pH of the mixed solution to 9 to obtain mixed solution I; (2) Add 120 parts of melamine, 65 parts of reinforcing resin liquid and 10 parts of propylene glycol to mixed solution I, heat to 80°C, stir for 2 hours, and then let it return to room temperature to obtain melamine impregnation solution for later use;

[0058] S3: Add 5.4 parts of TN-712 type curing agent, 3 parts of DF-9727 type release agent, and 3 parts of TN-737 type penetrant to the melamine impregnation solution. After stirring and mixing evenly, impregnate the high-strength base paper into the melamine impregnation solution. After repeated impregnation and drying twice, a high-strength compression-resistant balanced paper is obtained.

[0059] Example 3: A method for preparing a high-strength, compression-resistant balance paper:

[0060] S1: Preparation of high-strength base paper:

[0061] S11: At 45℃, 150 parts of corn starch were dispersed in deionized water to prepare a 45wt% starch suspension; then hydrochloric acid solution was added to adjust the pH to 2.5, and after stirring for 2 hours, 5wt% sodium hydroxide solution was added to adjust the pH to neutral. Finally, the suspension was filtered, washed, dried, pulverized and sieved to obtain the viscosity-reducing starch.

[0062] S12: (1) 7 parts of trichlorophosphazene, 0.29 parts of tetrabutylammonium bromide were dispersed into 73 parts of acetone, then heated to 70℃, and 13.2 parts of 2-hydroxy-5-aminopyridine was added thereto, and refluxed for 24h, and the reaction was ended, and finally, the product A was obtained by filtration, washing, and drying; (2) 10 parts of carboxymethyl chitosan was dispersed into 100 parts of 3v / v% dilute hydrochloric acid solution, then 15 parts of product A, 0.15 parts of dicyclohexyl carbodiimide, and 0.15 parts of 4-N,N-dimethylpyridine were added, and stirred at room temperature for 24h, and the reaction was ended, then 5wt% sodium hydroxide solution was added to adjust the pH to neutral, and finally, the flame retardant was obtained by filtration, washing, and drying;

[0063] S13: 100 parts of viscosity-reducing starch was dispersed into deionized water to prepare a 40wt% viscosity-reducing starch suspension; then 15wt% acetic acid solution was added to adjust the pH to 2.5, and heated to 70℃, and 20 parts of the flame retardant was added thereto, and refluxed for 12h, and the reaction was ended, and 5wt% sodium hydroxide solution was added to adjust the pH to neutral, and finally, the modified starch was obtained by filtration, washing, drying, crushing, and sieving;

[0064] S14: 1000 parts of paper pulp fibers were dispersed into deionized water to prepare an 8wt% paper pulp fiber suspension; then 100 parts of the modified starch, and 200 parts of sodium alginate were added, and stirred to mix uniformly to obtain a paper pulp liquid; and finally, the high-strength base paper was obtained by sheeting (sheeting amount: 70g / m 2 ), pressing, and drying;

[0065] S2: Preparation of melamine impregnation solution:

[0066] S21: (1) 5 parts of chitosan was dispersed into isopropyl alcohol to prepare a 5wt% chitosan suspension, then heated to 75℃, and 25 parts of glycidyltrimethylammonium chloride was slowly added thereto, and reacted for 5h, and the reaction was ended, and 40 parts of anhydrous ethanol was added and left to stand for 2h, and the precipitate was obtained, and finally, the modified chitosan I was obtained by filtration, washing, and drying; (2) 10 parts of the modified chitosan I, and 30 parts of allyl hydroxyethyl ether were added into a reaction vessel and mixed uniformly, then 3 parts of benzenesulfonic acid, and 0.2 parts of hydroquinone were added, and stirred at 140℃ for 20min, and the reaction was ended, and finally, the modified chitosan II was obtained by separation, washing, and drying; (3) 10 parts of the modified chitosan II, 50 parts of acrylamide, and 25 parts of glycidyl acrylate were added into a reaction vessel and mixed uniformly, then 0.35 parts of dibenzoyl peroxide was added, and stirred at 120℃ for 2h, and the reaction was ended, and the reinforcing resin solution was obtained;

[0067] S22: (1) mixed 200 parts of formaldehyde and 120 parts of deionized water, and adjusted the pH value of the mixed solution to 9 to obtain a mixed solution I; (2) added 120 parts of melamine, 65 parts of reinforcing resin liquid and 10 parts of propylene glycol into the mixed solution I, and heated to 80℃, stirred for 2h, then cooled to room temperature to obtain a melamine impregnating solution, which was used for standby;

[0068] S3: added 5.4 parts of TN-712 type curing agent, 3 parts of DF-9727 type release agent and 3 parts of TN-737 type penetrating agent into the melamine impregnating solution, and after stirring and mixing uniformly, immersed the high-strength base paper into the melamine impregnating solution, and repeated the immersion and drying twice to obtain the high-strength compression-resistant balanced paper.

[0069] Based on Example 1, the following comparative experiments were carried out, specifically Comparative Examples 1-5, which are described as follows:

[0070] Comparative Example 1: Comparative Example 1 was based on Example 1, and the adjustment was that the starch was not subjected to viscosity reduction treatment, and other processes remained unchanged, specifically:

[0071] S11: (1) dispersed 7 parts of trichlorophosphazene and 0.29 parts of tetrabutylammonium bromide into 73 parts of acetone, then heated to 70℃, and added 13.2 parts of 2-hydroxy-5-aminopyridine into the solution, refluxed for 15h, and then filtered, washed and dried to obtain product A; (2) dispersed 10 parts of carboxymethyl chitosan into 100 parts of 3v / v% dilute hydrochloric acid solution, then added 13 parts of product A, 0.15 parts of dicyclohexyl carbodiimide and 0.15 parts of 4-N,N-dimethylpyridine, and stirred at room temperature for 18h, then added 5wt% sodium hydroxide solution to adjust the pH to neutral, and finally filtered, washed and dried to obtain a flame retardant;

[0072] S12: dispersed 100 parts of corn starch into deionized water to prepare a 40wt% viscosity-reduced starch suspension; then added 15wt% acetic acid solution to adjust the pH to 2.5, heated to 70℃, and added 15 parts of the flame retardant into the solution, refluxed for 8h, then added 5wt% sodium hydroxide solution to adjust the pH to neutral, and finally filtered, washed, dried, crushed and sieved to obtain modified starch;

[0073] S13: dispersed 1000 parts of paper pulp fiber into deionized water to prepare an 8wt% paper pulp fiber suspension; then added 75 parts of modified starch and 200 parts of sodium alginate, and stirred and mixed uniformly to obtain a paper pulp liquid; finally, sheeted (sheeted amount 70g / m 2 ), pressed and dried to obtain high-strength base paper.

[0074] Comparative Example 2: Comparative Example 2 is based on Example 1, with the following adjustment: corn starch is only subjected to viscosity reduction treatment, and other processes remain unchanged, specifically:

[0075] S11: 150 parts of corn starch were dispersed in deionized water to prepare a 45 wt% starch suspension at 45°C; then hydrochloric acid solution was added to adjust the pH to 2.5, and after stirring for 2 h, 5 wt% sodium hydroxide solution was added to adjust the pH to neutral; finally, filtration, washing, drying, crushing, and sieving were performed to obtain viscosity-reduced starch;

[0076] S12: 1000 parts of pulp fibers were dispersed in deionized water to prepare an 8 wt% pulp fiber suspension; then 75 parts of viscosity-reduced starch and 200 parts of sodium alginate were added and stirred to obtain a pulp liquid; finally, sheeting (sheeting amount 70 g / m 2 ), pressing, and drying were performed to obtain high-strength base paper.

[0077] Comparative Example 3: Comparative Example 3 is based on Example 1, with the following adjustment: no sodium alginate is added to the pulp liquid, and other processes remain unchanged, specifically:

[0078] S14: 1000 parts of pulp fibers were dispersed in deionized water to prepare an 8 wt% pulp fiber suspension; then 75 parts of modified starch were added and stirred to obtain a pulp liquid; finally, sheeting (sheeting amount 70 g / m 2 ), pressing, and drying were performed to obtain high-strength base paper.

[0079] Comparative Example 4: Comparative Example 4 is based on Example 1, with the following adjustment: no modified chitosan II is added to the melamine impregnation solution, and other processes remain unchanged, specifically:

[0080] S21: 50 parts of acrylamide and 25 parts of glycidyl acrylate were added to a reaction container and mixed uniformly, then 0.35 parts of dibenzoyl peroxide was added, and stirring was performed at 120°C for 2 h to complete the reaction, thereby obtaining a reinforcing resin solution;

[0081] S22: (1) 200 parts of formaldehyde and 120 parts of deionized water were mixed, and the pH of the mixed solution was adjusted to 9 to obtain mixed solution I; (2) 120 parts of melamine, 65 parts of the reinforcing resin solution, and 10 parts of propylene glycol were added to mixed solution I, and the temperature was raised to 80°C, stirring was performed for 2 h, and then the solution was allowed to cool to room temperature to obtain a melamine impregnation solution, which was reserved.

[0082] Comparative Example 5: Comparative Example 5 is based on Example 1, with the following adjustment: no reinforcing resin solution is added to the melamine impregnation solution, and other processes remain unchanged, specifically:

[0083] S21: (1) 200 parts of formaldehyde, 120 parts of deionized water were mixed, and the pH value of the mixed solution was adjusted to 9 to obtain a mixed solution I; (2) 120 parts of melamine, 10 parts of propylene glycol were added to the mixed solution I, and the temperature was raised to 80℃, stirred for 2h, then cooled to room temperature to obtain a melamine impregnating solution, ready for use.

[0084] In the above examples, all raw materials are as follows: trichlorophosphazene, 2-hydroxy-5-amino pyridine, purity 98%, purchased from Zhengzhou Alpha Chemical Co., Ltd.; tetrabutylammonium bromide, carboxymethyl chitosan, chitosan, dicyclohexyl carbodiimide, 4-N,N-dimethylpyridine, sodium alginate, glycidyltrimethylammonium chloride, benzene sulfonic acid, melamine, purity 99%, Hubei Jusheng Technology Co., Ltd.; allyl hydroxyethyl ether, hydroquinone, acrylamide, glycidyl acrylate, propylene glycol, methanol, purity 99%, purchased from Shanghai Jinjinle Industry Co., Ltd.; TN-712 type curing agent, TN-737 type penetrant, purchased from Changzhou Tianuo Environmental Protection New Material Co., Ltd.; DF-9727 type release agent, purchased from Shandong Defeng Polyurethane (Release Agent) Group Co., Ltd.

[0085] Performance test: the high-strength compression-resistant balanced paper prepared in examples 1-3 and comparative examples 1-5 was tested for related performance, as follows:

[0086] (1) According to the standard of GB / T 454-2020, the burst resistance test was carried out;

[0087] (2) According to the standard of GB / T 12914-2018, the tensile strength test was carried out;

[0088] (3) According to the standard of UL94-2018, the flame retardant performance test was carried out;

[0089] (4) The water contact angle was measured by a contact angle measuring instrument to evaluate the hydrophobicity; the specific test results are shown in Table 1 below:

[0090]

[0091] Result analysis: from the data in Table 1 above, it can be seen that by further modifying the viscosity-reducing starch in the scheme, modified starch is prepared, which significantly improves the strength of the base paper together with sodium alginate; in addition, the reinforcing resin solution is further prepared in the present application, which also has a significant improvement effect on the strength of melamine resin, and at the same time endows the prepared balanced paper with excellent flame retardant performance and hydrophobicity. That is, the present application finally prepares a high-strength compression-resistant balanced paper, which also has excellent flame retardant performance and hydrophobicity, and can effectively protect the wood floor.

[0092] Finally, it should be noted that: the above only for the preferred embodiments of the present application, but the scope of the present application does not limit this, within the spirit and principles of the present application, any skilled in the art of the technical personnel in the technical range of the present application, can easily think of changes or replacement, should be covered in the scope of the present application; in the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other. Therefore, the scope of protection of the present application should be subject to the scope of protection of the claims.

Claims

1. A method of making a high-strength, compression-resistant, balanced paper, characterized by: The method comprises the following steps: S1: preparing high-strength base paper: first, starch is subjected to viscosity reduction treatment, and then grafted with a flame retardant to obtain modified starch; then, the modified starch, pulp fibers, sodium alginate and deionized water are uniformly mixed to obtain a pulp liquid; finally, the high-strength base paper is obtained through sheet forming, pressing, drying and cutting; The preparation method of the flame retardant is as follows: (1) dispersing trichlorophosphazene and tetrabutylammonium bromide into ten times the weight of acetone, then heating to 60-80℃, adding 2-hydroxy-5-aminopyridine into the solution, refluxing for 12-24h, ending the reaction, and finally filtering, washing and drying to obtain product A; (2) dispersing carboxymethyl chitosan into ten times the weight of 2-4v / v% dilute hydrochloric acid solution, then adding product A, a condensation agent and an acylation catalyst, stirring at room temperature for 6-24h, ending the reaction, adding sodium hydroxide solution to adjust the pH to neutral, and finally filtering, washing and drying to obtain the flame retardant; S2: preparing melamine impregnating solution: first, chitosan is sequentially reacted with glycidyltrimethylammonium chloride, allyl hydroxyethyl ether and acrylamide and glycidyl acrylate to obtain an enhanced resin solution; then, formaldehyde, melamine, the enhanced resin solution, propylene glycol and deionized water are uniformly mixed to obtain the melamine impregnating solution; The preparation method of the enhanced resin solution is as follows: (1) dispersing chitosan into isopropyl alcohol to prepare a 5-10wt% chitosan suspension, then heating to 70-80℃, slowly adding glycidyltrimethylammonium chloride into the solution, reacting for 2-6h, adding anhydrous ethanol and standing for 1-2h to precipitate, and finally filtering, washing and drying to obtain modified chitosan I; (2) adding modified chitosan I and allyl hydroxyethyl ether into a reaction container, uniformly mixing, adding benzenesulfonic acid and hydroquinone, stirring at 130-150℃ for 10-30min, ending the reaction, and finally separating, washing and drying to obtain modified chitosan II; (3) adding modified chitosan II, acrylamide and glycidyl acrylate into a reaction container, uniformly mixing, adding dibenzoyl peroxide, stirring at 110-130℃ for 1-3h, ending the reaction, and obtaining the enhanced resin solution; S3: adding a curing agent, a release agent and a penetrating agent into the melamine impregnating solution, uniformly mixing, and then impregnating the high-strength base paper into the solution, repeating the impregnation twice, and drying to obtain the high-strength compression-resistant balanced paper.

2. A process for the preparation of high strength, compression resistant, balanced paper as claimed in claim 1, wherein: The specific steps of S1 include: S11: dispersing starch into deionized water at 40-50℃ to prepare a 40-50wt% starch suspension; then adding hydrochloric acid solution to adjust the pH to 2-4, stirring for 1-3h, adding sodium hydroxide solution to adjust the pH to neutral, and finally filtering, washing, drying, crushing and sieving to obtain viscosity-reduced starch; S12: Disperse the viscosity-reducing starch into deionized water to prepare a 30-50wt% viscosity-reducing starch suspension; then add 10-20wt% acetic acid solution to adjust the pH to 2-4, heat to 60-80℃, and add the flame retardant thereto, reflux for 6-12h, end the reaction, add sodium hydroxide solution to adjust the pH to neutral, and finally filter, wash, dry, crush, and sieve to obtain the modified starch; S13: Disperse the pulp fibers into deionized water to prepare a 5-10wt% pulp fiber suspension; then add the modified starch and sodium alginate, mix uniformly, and obtain the pulp liquid; and finally sheet, press, and dry to obtain the high-strength base paper.

3. A process for the preparation of high strength, compression resistant, balanced paper as claimed in claim 1, wherein: The molar ratio of the phosphazene trichloride and 2-hydroxy-5-aminopyridine is 1:6; the amount of the tetrabutylammonium bromide added is 3-5% of the mass of the phosphazene trichloride; and the mass ratio of the carboxymethyl chitosan, product A, condensing agent, and acylation catalyst is 1:(1-1.5):(0.01-0.02):(0.01-0.02).

4. A process for the preparation of high strength, compression resistant, balanced paper as claimed in claim 2, wherein: The mass ratio of the viscosity-reducing starch and flame retardant is 10:(1-2).

5. A process for the preparation of high strength, compression resistant, balanced paper as claimed in claim 2, wherein the said process is characterized by: The mass ratio of the pulp fiber, modified starch, and sodium alginate is 10:(0.5-1):

2.

6. A process for the preparation of high strength, compression resistant, balanced paper as claimed in claim 3, wherein the said process is characterized by: The condensing agent includes any one of dicyclohexyl carbodiimide, diisopropyl carbodiimide, and 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide; and the acylation catalyst includes any one of 4-N,N-dimethylpyridine and 1-hydroxybenzotriazole.

7. A process for the preparation of high strength, compression resistant, balanced paper as claimed in claim 1, wherein the said process is characterized by: The specific steps of S2 include: (1) mixing formaldehyde and deionized water, and adjusting the pH of the solution to 8-10 to obtain a mixed solution I; (2) adding melamine, enhanced resin liquid, and propylene glycol to the mixed solution I, heating to 80-90℃, stirring for 1-2h, and then waiting for it to return to room temperature to obtain a melamine impregnation liquid.

8. A process for the preparation of high strength, compression resistant, balanced paper as claimed in claim 1, wherein: The mass ratio of the chitosan and glycidyltrimethylammonium chloride is 1:(4-5); the mass ratio of the modified chitosan I, allyl hydroxyethyl ether, benzenesulfonic acid, and hydroquinone is 1:(1-3):(0.2-0.5):(0.01-0.03); and the mass ratio of the modified chitosan II, acrylamide, glycidyl acrylate, and dibenzoyl peroxide is (1-2):10:5:(0.05-0.1).

9. A process for the preparation of high strength, compression resistant, balanced paper as claimed in claim 7, wherein: The melamine impregnation liquid includes the following components: by weight, melamine 100-150 parts, formaldehyde 150-250 parts, enhanced resin liquid 50-80 parts, propylene glycol 5-15 parts, and deionized water 80-150 parts.

10. A high-strength compression-resistant balanced paper prepared by the method according to any one of claims 1-9.

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