Preparation method of enhanced modified cationic surface sizing agent

Abstract

The invention relates to the technical field of papermaking chemicals, in particular to a preparation method of an enhanced modified cationic surface sizing agent. According to the invention, the prepared antibacterial agent has excellent antibacterial performance under the synergistic effect of the nano titanium dioxide and the chitosan quaternary ammonium salt; furthermore, the cationic starch and the nano silicon dioxide are added, so that the binding force between the sizing agent and paper fibers is enhanced, and the mechanical property of the paper is enhanced; in addition, the prepared surface sizing agent can form a more compact protective film on the surface of paper, so that the water resistance of the paper is remarkably improved; in conclusion, the prepared surface sizing agent not only can effectively enhance the mechanical property of paper, but also can effectively improve the water resistance and antibacterial property of the paper, so that the service life of the paper is prolonged to a certain extent, and the quality of the paper is effectively ensured.

Description

Technical Field

[0001] The invention relates to the technical field of papermaking chemicals, and in particular to a preparation method of an enhanced modified cationic surface sizing agent. Background Art

[0002] Surface sizing is a crucial step in papermaking. Its purpose is to form a continuous protective film on the paper surface, thereby improving the paper's water resistance, surface strength, and other properties. Cationic surface sizing agents are widely used in paper surface sizing because they can electrostatically adsorb to negatively charged paper fibers.

[0003] The patent document with application number "CN201310142135.7" discloses a method for preparing and applying a paper surface sizing agent, which includes the following steps: (1) Preparation of nano-microcrystalline cellulose colloid: using microcrystalline cellulose as raw material, it is prepared by sulfuric acid hydrolysis. (2) Preparation process of surface sizing agent: first, place the gelatinized cationic starch in a beaker and stir it on a magnetic stirrer, while stirring, add the nano-microcrystalline cellulose colloid to the cationic starch, and finally stir evenly at the stirring speed to obtain a cationic starch composite sizing agent. (3) Application process: lay the base paper flat on a glass plate and fix one end, use a surface sizing rod to evenly apply a certain amount of sizing agent on the surface of the base paper, and then let the sized paper air dry for a certain period of time and then dry it in a dryer. Although the surface sizing agent prepared by this invention patent can significantly improve the physical properties of the paper surface such as tensile strength, tear resistance, and burst resistance, the degree of improvement is relatively small. At the same time, its own water resistance is relatively insufficient and its function is relatively simple. Therefore, the present invention provides a method for preparing an enhanced modified cationic surface sizing agent, aiming to solve the above-mentioned technical problems. Summary of the Invention

[0004] The object of the present invention is to provide a method for preparing an enhanced modified cationic surface sizing agent. The prepared surface sizing agent can not only effectively enhance the mechanical properties of paper, but also effectively improve its water resistance and antibacterial properties, thereby extending its service life to a certain extent and effectively ensuring its quality.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for preparing an enhanced modified cationic surface sizing agent comprises the following steps:

[0007] Step 1, cationic starch and deionized water are added into a reactor at a mass ratio of 1:8-10, and mixed and stirred at a speed of 250-350 r / min for 20-30 minutes; then the reactor temperature is raised to 80-90° C., and the reaction is kept at this temperature for 30-50 minutes. After the reaction is completed, the temperature is lowered to 70-80° C., and a styrene-acrylate copolymer emulsion with a mass 1-1.5 times that of the cationic starch is slowly added, and the mixture is stirred at a speed of 150-250 r / min for 15-20 minutes. The resulting mixed components are stored for future use;

[0008] Step 2: Add melamine formaldehyde resin with a mass ratio of 20-25% of cationic starch to the mixed components obtained in step 1, and add an appropriate amount of reaction accelerator. After mixing and stirring, raise the temperature of the resulting mixture to 60-70° C. and stir at a rate of 100-200 r / min for 2-3 hours; the resulting reaction product is stored for future use;

[0009] Step 3: After the reaction is completed, the reaction product obtained in step 2 is naturally cooled to 40-50°C, and then cetyltrimethylammonium bromide with a mass of 1-2% of the reaction product and an aqueous dispersion of an antibacterial agent with a volume of 6-12% of the reaction product and a concentration of 50-80g / L are added, and the mixture is mixed and stirred at a speed of 250-400r / min for 30-40min to obtain an enhanced modified cationic surface sizing agent.

[0010] Furthermore, the degree of substitution of the cationic starch is 0.03 to 0.05.

[0011] Furthermore, the solid content of the styrene-acrylate copolymer emulsion is 40-50%.

[0012] Furthermore, the molecular weight of the melamine formaldehyde resin is between 500 and 1000.

[0013] Furthermore, the reaction accelerator is selected from any one of potassium persulfate and ammonium persulfate.

[0014] Furthermore, the preparation method of the antibacterial agent is as follows: chitosan quaternary ammonium salt is uniformly dissolved in a buffer solution at a dosage ratio of 50 to 80 g / L, glutaraldehyde is then added in a molar amount of 15 to 20% of the chitosan quaternary ammonium salt, and after stirring at room temperature for 2 to 5 hours, pre-treated nano-titanium dioxide in a molar amount of 0.3 to 0.5 times that of the chitosan quaternary ammonium salt is slowly added dropwise to the obtained product components, and after mixing and stirring evenly, the mixture is kept warm and stirred at a temperature of 55 to 65° C. for 6 to 10 hours; after the reaction is completed, the obtained product components are sequentially subjected to solid-liquid separation, washing and vacuum drying treatment to obtain the antibacterial agent.

[0015] Furthermore, the vacuum drying temperature is set to 70-90° C., and the vacuum drying time is set to 80-120 min.

[0016] Furthermore, the buffer solution is a phosphate buffered saline solution with a pH value of 7.4.

[0017] Furthermore, the preparation method of the pretreated nano titanium dioxide is: putting nano titanium dioxide into a high-temperature calcination device and calcining it at a temperature of 450-550°C for 3-4 hours; after the calcination is completed, naturally cooling it to room temperature to obtain the pretreated nano titanium dioxide.

[0018] Furthermore, the chitosan quaternary ammonium salt is selected from any one of hydroxypropyltrimethylammonium chloride chitosan, N-(2-hydroxypropyl)trimethylammonium chloride chitosan, and carboxymethyl chitosan quaternary ammonium salt.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention is earlier dissolved in the buffered solution with chitosan quaternary ammonium salt, then to wherein adding glutaraldehyde, question response is complete, in the gained resultant component, add pre-treatment nano titanium dioxide, mix and stir evenly after " bridge " effect of glutaraldehyde, make chitosan quaternary ammonium salt bond to the surface of pre-treatment nano titanium dioxide, finally make prepared antibacterial agent have excellent antimicrobial property under the synergistic coordination effect of nano titanium dioxide and chitosan quaternary ammonium salt. Moreover, the adding of cationic starch and nano silicon dioxide has strengthened the bonding force between sizing agent and the paper fiber, has strengthened the mechanical property of paper. In addition, the surface sizing agent prepared by the present invention can form more fine and close protective film on paper surface, thereby has significantly improved the water resistance of paper.

[0021] In summary, the surface sizing agent prepared by the present invention can not only effectively enhance the mechanical properties of paper, but also effectively improve its water resistance and antibacterial properties, thereby extending its service life to a certain extent and effectively ensuring its quality. DETAILED DESCRIPTION

[0022] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0023] Example 1

[0024] A method for preparing an enhanced modified cationic surface sizing agent comprises the following steps:

[0025] Step 1: cationic starch and deionized water are added to a reactor in a mass ratio of 1:8, and mixed and stirred at a speed of 250 r / min for 20 minutes; then the reactor temperature is raised to 80°C, and the reaction is kept at this temperature for 30 minutes. After the reaction is completed, the temperature is lowered to 70°C, and a styrene-acrylate copolymer emulsion of the same mass as the cationic starch is slowly added, and the mixture is stirred at a speed of 150 r / min for 15 minutes. The resulting mixed components are stored for future use;

[0026] Step 2: Add melamine formaldehyde resin with a mass ratio of 20% of cationic starch to the mixed components obtained in step 1, and add an appropriate amount of reaction accelerator. After mixing and stirring, raise the temperature of the resulting mixture to 60° C. and stir at a rate of 100 r / min for 2 hours. The resulting reaction product is stored for future use.

[0027] Step 3, after the reaction is completed, the reaction product obtained in step 2 is naturally cooled to 40 ° C, and then cetyltrimethylammonium bromide with a mass of 1% of the reaction product and an antibacterial agent aqueous dispersion with a volume of 6% of the reaction product and a concentration of 50g / L are added, and mixed and stirred at a speed of 250r / min for 30min to obtain an enhanced modified cationic surface sizing agent;

[0028] The substitution degree of cationic starch is 0.03; the solid content of styrene-acrylate copolymer emulsion is 40%; the molecular weight of melamine formaldehyde resin is 500; and potassium persulfate is selected as a reaction accelerator.

[0029] The preparation method of the antibacterial agent comprises the following steps: uniformly dissolving chitosan quaternary ammonium salt in a buffer solution at a dosage ratio of 50 g / L, then adding glutaraldehyde in a molar amount of 15% of the chitosan quaternary ammonium salt, stirring at room temperature for 2 hours, slowly dropwise adding pre-treated nano-titanium dioxide in a molar amount of 0.3 times that of the chitosan quaternary ammonium salt to the resulting component, stirring evenly, and then stirring at a temperature of 55° C. for 10 hours; after the reaction is completed, sequentially performing solid-liquid separation, washing, and vacuum drying on the resulting component to obtain the antibacterial agent;

[0030] The vacuum drying temperature is set to 70°C, and the vacuum drying time is set to 120 minutes; the buffer solution is a phosphate buffered saline solution with a pH value of 7.4; the chitosan quaternary ammonium salt is hydroxypropyltrimethylammonium chloride chitosan;

[0031] The preparation method of pre-treated nano titanium dioxide is as follows: putting nano titanium dioxide into a high-temperature calcination device and calcining it at a temperature of 450° C. for 4 hours; after the calcination is completed, naturally cooling it to room temperature to obtain pre-treated nano titanium dioxide.

[0032] Example 2

[0033] A method for preparing an enhanced modified cationic surface sizing agent comprises the following steps:

[0034] Step 1: cationic starch and deionized water are added to a reactor in a mass ratio of 1:9, and mixed and stirred at a speed of 300 r / min for 20 to 30 minutes; then the reactor temperature is raised to 85°C, and the reaction is kept at this temperature for 40 minutes. After the reaction is completed, the temperature is lowered to 75°C, and a styrene-acrylate copolymer emulsion with a mass 1.2 times that of the cationic starch is slowly added, and the mixture is stirred at a speed of 200 r / min for 20 minutes. The resulting mixed components are stored for future use;

[0035] Step 2: Add melamine formaldehyde resin with a mass ratio of 25% of cationic starch to the mixed components obtained in step 1, and add an appropriate amount of reaction accelerator. After mixing and stirring, raise the temperature of the resulting mixture to 65° C. and stir at a rate of 150 r / min for 3 hours; the resulting reaction product is stored for future use;

[0036] Step 3, after the reaction is completed, the reaction product obtained in step 2 is naturally cooled to 45 ° C, and then cetyltrimethylammonium bromide with a mass of 1.5% of the reaction product and an antibacterial agent aqueous dispersion with a volume of 10% of the reaction product and a concentration of 60g / L are added, and mixed and stirred at a speed of 250-400r / min for 35min to obtain an enhanced modified cationic surface sizing agent;

[0037] The substitution degree of cationic starch is 0.04; the solid content of styrene-acrylate copolymer emulsion is 45%; the molecular weight of melamine formaldehyde resin is 500; and ammonium persulfate is selected as the reaction accelerator.

[0038] The preparation method of the antibacterial agent comprises the following steps: uniformly dissolving chitosan quaternary ammonium salt in a buffer solution at a dosage ratio of 60 g / L, then adding glutaraldehyde in a molar amount of 20% of the chitosan quaternary ammonium salt, stirring at room temperature for 3 hours, slowly dropwise adding pre-treated nano-titanium dioxide in a molar amount of 0.4 times that of the chitosan quaternary ammonium salt to the resulting component, stirring evenly, and then stirring at 60° C. for 8 hours; after the reaction is completed, sequentially performing solid-liquid separation, washing, and vacuum drying on the resulting component to obtain the antibacterial agent;

[0039] The vacuum drying temperature is set to 80° C., and the vacuum drying time is set to 100 min. The buffer solution is a phosphate buffered saline solution with a pH value of 7.4. The chitosan quaternary ammonium salt is N-(2-hydroxypropyl)trimethylammonium chloride chitosan.

[0040] The preparation method of pre-treated nano titanium dioxide is as follows: putting nano titanium dioxide into a high-temperature calcination device and calcining it at a temperature of 500°C for 4 hours; after the calcination is completed, cooling it naturally to room temperature to obtain pre-treated nano titanium dioxide.

[0041] Example 3

[0042] A method for preparing an enhanced modified cationic surface sizing agent comprises the following steps:

[0043] Step 1: cationic starch and deionized water are added to a reactor in a mass ratio of 1:10, and mixed and stirred at a speed of 350 r / min for 30 minutes; then the reactor temperature is raised to 90°C, and the reaction is kept at this temperature for 50 minutes. After the reaction is completed, the temperature is lowered to 80°C, and a styrene-acrylate copolymer emulsion with a mass 1.5 times that of the cationic starch is slowly added, and the mixture is stirred at a speed of 250 r / min for 20 minutes. The resulting mixed components are stored for future use;

[0044] Step 2: Add melamine formaldehyde resin with a mass ratio of 25% of cationic starch to the mixed components obtained in step 1, and add an appropriate amount of reaction accelerator. After mixing and stirring, raise the temperature of the resulting mixture to 70° C. and stir at a rate of 200 r / min for 3 hours. The resulting reaction product is stored for future use.

[0045] Step 3, after the reaction is completed, the reaction product obtained in step 2 is naturally cooled to 50 ° C, and then cetyltrimethylammonium bromide with a mass of 2% of the reaction product and an antibacterial agent aqueous dispersion with a volume of 12% of the reaction product and a concentration of 80g / L are added, and mixed and stirred at a speed of 400r / min for 40min to obtain an enhanced modified cationic surface sizing agent;

[0046] The substitution degree of cationic starch is 0.05; the solid content of styrene-acrylate copolymer emulsion is 50%; the molecular weight of melamine formaldehyde resin is 1000; and potassium persulfate is selected as a reaction accelerator.

[0047] The preparation method of the antibacterial agent comprises the following steps: uniformly dissolving chitosan quaternary ammonium salt in a buffer solution at a dosage ratio of 80 g / L, then adding glutaraldehyde in a molar amount of 20% of the chitosan quaternary ammonium salt, stirring at room temperature for 5 hours, slowly dropwise adding pre-treated nano-titanium dioxide in a molar amount of 0.5 times that of the chitosan quaternary ammonium salt to the resulting component, stirring evenly, and then stirring at a temperature of 65° C. for 6 hours; after the reaction is completed, sequentially performing solid-liquid separation, washing, and vacuum drying on the resulting component to obtain the antibacterial agent;

[0048] The vacuum drying temperature is set to 90°C, and the vacuum drying time is set to 80 minutes; the buffer solution is a phosphate buffered saline solution with a pH value of 7.4; the chitosan quaternary ammonium salt is a carboxymethyl chitosan quaternary ammonium salt;

[0049] The preparation method of pre-treated nano titanium dioxide is as follows: putting nano titanium dioxide into a high-temperature calcination device and calcining it at a temperature of 550° C. for 3 hours; after the calcination is completed, naturally cooling it to room temperature to obtain pre-treated nano titanium dioxide.

[0050] Performance Test: The base paper was laid flat on a glass plate and fixed at one end. The surface sizing agents prepared in Examples 1 to 3 were uniformly applied to the surface of the base paper using a surface sizing rod. The surface sizing agent was added in an amount of 0.3 wt % at a sizing speed of 50 m / min. The sized paper was air-dried for 3 minutes and then dried in a dryer for 3 minutes at 105°C. The relevant properties of each group of sized paper were then tested, and the test results are recorded in the following table:

[0051]

[0052] Comparison and analysis of the relevant data in the table show that the surface sizing agent prepared by the present invention not only effectively enhances the mechanical properties of paper, but also effectively improves its water resistance and antibacterial properties, extending its service life to a certain extent while effectively ensuring its quality. This demonstrates that the preparation method of the enhanced modified cationic surface sizing agent provided by the present invention has a broader market prospect and is more suitable for promotion.

[0053] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0054] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing an enhanced modified cationic surface sizing agent, characterized in that: The following steps are involved: Step 1, cationic starch and deionized water are added into a reactor at a mass ratio of 1:8-10, and mixed and stirred at a speed of 250-350 r / min for 20-30 minutes; then the reactor temperature is raised to 80-90° C., and the reaction is kept at this temperature for 30-50 minutes. After the reaction is completed, the temperature is lowered to 70-80° C., and a styrene-acrylate copolymer emulsion with a mass 1-1.5 times that of the cationic starch is slowly added, and the mixture is stirred at a speed of 150-250 r / min for 15-20 minutes. The resulting mixed components are stored for future use; Step 2: Add melamine formaldehyde resin with a mass ratio of 20-25% of cationic starch to the mixed components obtained in step 1, and add an appropriate amount of reaction accelerator. After mixing and stirring, raise the temperature of the resulting mixture to 60-70° C. and stir at a rate of 100-200 r / min for 2-3 hours; the resulting reaction product is stored for future use; Step 3: After the reaction is completed, the reaction product obtained in step 2 is naturally cooled to 40-50°C, and then cetyltrimethylammonium bromide with a mass of 1-2% of the reaction product and an aqueous dispersion of an antibacterial agent with a volume of 6-12% of the reaction product and a concentration of 50-80g / L are added, and the mixture is mixed and stirred at a speed of 250-400r / min for 30-40min to obtain an enhanced modified cationic surface sizing agent.

2. The method for preparing a reinforced modified cationic surface sizing agent according to claim 1, wherein: The substitution degree of the cationic starch is 0.03 to 0.

05.

3. The method for preparing a reinforced modified cationic surface sizing agent according to claim 1, wherein: The solid content of the styrene-acrylate copolymer emulsion is 40-50%.

4. The method for preparing a reinforced modified cationic surface sizing agent according to claim 1, wherein: The molecular weight of the melamine formaldehyde resin is between 500 and 1000.

5. The method for preparing a reinforced modified cationic surface sizing agent according to claim 1, characterized in that: The reaction accelerator is selected from potassium persulfate and ammonium persulfate.

6. The method for preparing a reinforced modified cationic surface sizing agent according to claim 1, characterized in that: The preparation method of the antibacterial agent comprises the following steps: uniformly dissolving chitosan quaternary ammonium salt in a buffer solution at a dosage ratio of 50 to 80 g / L, then adding glutaraldehyde in a molar amount of 15 to 20% of the chitosan quaternary ammonium salt, stirring at room temperature for reaction for 2 to 5 hours, slowly dropwise adding pre-treated nano-titanium dioxide in a molar amount of 0.3 to 0.5 times that of the chitosan quaternary ammonium salt to the obtained product components, stirring and mixing evenly, and then stirring and reacting at a temperature of 55 to 65° C. for 6 to 10 hours; and after the reaction is completed, sequentially performing solid-liquid separation, washing and vacuum drying on the obtained product components to obtain the antibacterial agent.

7. The method for preparing a reinforced modified cationic surface sizing agent according to claim 6, characterized in that: The vacuum drying temperature is set to 70-90° C., and the vacuum drying time is set to 80-120 min.

8. The method for preparing a reinforced modified cationic surface sizing agent according to claim 6, characterized in that: The buffer solution is a phosphate buffered saline solution with a pH value of 7.

4.

9. The method for preparing a reinforced modified cationic surface sizing agent according to claim 6, characterized in that: The preparation method of the pretreated nano titanium dioxide is as follows: putting the nano titanium dioxide into a high temperature calcination device and calcining it at a temperature of 450-550° C. for 3-4 hours; after the calcination is completed, cooling it naturally to room temperature to obtain the pretreated nano titanium dioxide.

10. The method for preparing a reinforced modified cationic surface sizing agent according to claim 6, characterized in that: The chitosan quaternary ammonium salt is selected from any one of hydroxypropyl trimethyl ammonium chloride chitosan, N-(2-hydroxypropyl) trimethyl ammonium chloride chitosan, and carboxymethyl chitosan quaternary ammonium salt.

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