A method for preparing an emulsifier for high charge density AKD

Abstract

The present invention relates to the technical field of preparation of surfactant for AKD, and specifically to a method for preparing an emulsifier for AKD with high charge density, comprising the following steps: S1, preparing an aqueous solution of cassava starch; S2, adding an oxidant to the aqueous solution of cassava starch, adjusting the pH value of the system, and keeping the temperature at a first temperature for reaction; S3, after the reaction of step S2 is completed, heating to a second temperature, adding alkali solution, heating to a third temperature, adding a cationic etherifying agent, and keeping the temperature for reaction; S4, adding acid to the reaction system in step S3 to terminate the reaction; S5, adding a dispersant to the reaction product of step S4, heating to a fourth temperature, cooling after keeping the temperature, and obtaining a finished product. The emulsifier for AKD prepared by the present invention has a charge density of 179-187meq / g, enhances the bonding strength with AKD particles, has a good emulsification effect, is simple in preparation method, and is suitable for industrial-scale production.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of surfactant for AKD, and in particular to a preparation method of an emulsifier for AKD with high charge density. Background Art

[0002] AKD is the abbreviation of the English name alkyl ketene dimer, which means alkyl ketene dimer. AKD emulsion is a commonly used internal sizing agent in papermaking. Due to its low price and good water resistance, it is widely used in packaging paper, cultural paper, recycled paper and other aspects. Since AKD itself has no charge, it is difficult to retain on the fiber. Generally, a cationic emulsifier is needed to emulsify AKD so that AKD carries a positive charge and adsorbs on the negatively charged fiber. Cationic emulsifiers not only have high positive charge, but also have self-retention and synergistic effects, which effectively improve the stability of AKD emulsion, reduce the amount used, and shorten the sizing maturation time. At present, most of the AKD emulsions on the market are prepared with cationic starch as an emulsifier, but cationic starch has a low charge density, a large molecular weight, and a low bonding strength with AKD particles. The stability and sizing effect of the AKD emulsion prepared with it are poor.

[0003] CN146279451A discloses a high-substitution cationic starch and a preparation method thereof, the preparation method comprising the following steps:

[0004] (1) Mixing starch with an organic solvent aqueous solution having a concentration of 86-144 wt % and placing the mixture in a reaction container, wherein the mass ratio of the starch to the organic solvent is 1:4.5-3; (2) Dissolving a catalyst and an etherifying agent in water, adding the mixture to the reaction container, stirring and heating the mixture to 54-85° C., and reacting the mixture for 4.5-5 hours; (3) Adding an oxidant and reacting the mixture for 5-64 minutes; (4) Adding an acid until the pH value of the reaction system reaches 4-7; (5) Adding a cross-linking agent and reacting the mixture for 4-184 minutes; and (6) Vacuum drying the mixture at a temperature of 54-115° C. and a vacuum degree of 4.47-4.1 MPa to obtain the highly substituted cationic starch.

[0005] CN144193839A discloses a cationic starch and its preparation method and application. The preparation method comprises: (1) mixing starch with an organic solvent aqueous solution with a mass percentage of 54-94% and placing the mixture in a reaction vessel; (2) adding a catalyst, stirring and heating to 54-94°C; (3) adding an etherifying agent and reacting for 1-5 hours; (4) adding an oxidizing agent and reacting for 14-64 minutes; (5) adding an acid until the pH value of the reaction system is 4-7; (6) vacuum drying at a temperature of 54-94°C and a vacuum degree of 4.47-4.1MPa to obtain the cationic starch. The cationic starch prepared by the preparation method of the present invention can be used as an AKD emulsifier to stabilize the AKD emulsion for more than 3 months at room temperature.

[0006] The above patent first etherifies the starch and then oxidizes it. The oxidant will affect the charge of the etherified starch, causing the charge density of the cationic starch to decrease, thus affecting the emulsification property. Summary of the invention

[0007] In view of the problems of low charge density and poor emulsification performance of the prior art AKD emulsifier, the present invention provides a method for preparing an emulsifier for AKD with high charge density. The prepared emulsifier for AKD has a charge density of 179-187 meq / g, enhanced bonding strength with AKD particles, good emulsification effect, simple preparation method, and is suitable for industrial-scale production.

[0008] The present invention provides a method for preparing an emulsifier for high charge density AKD, comprising the following steps:

[0009] S1, preparing an aqueous solution of tapioca starch;

[0010] S2, adding an oxidant to the aqueous solution of cassava starch, adjusting the pH value of the system, and keeping the reaction at a first temperature;

[0011] S3, after the reaction of step S2 is completed, the temperature is raised to the second temperature, an alkali solution is added, the temperature is raised to the third temperature, a cationic etherifying agent is added, and the temperature is kept for reaction;

[0012] S4, adding acid to the reaction system in step S3 to terminate the reaction;

[0013] S5. Add a dispersant to the reaction product of step S4, raise the temperature to a fourth temperature, keep the temperature and then cool down to obtain a finished product.

[0014] Furthermore, in step S2, the aqueous solution of cassava starch begins to cool down when the oxidant is added, and the first temperature is 15-24°C.

[0015] Furthermore, in step S2, the oxidant is sodium hypochlorite.

[0016] Furthermore, in step S2, the pH value of the system is adjusted to 8.5-9.5.

[0017] Furthermore, in step S3, the second temperature is 44-74° C., the third temperature is 54-84° C., and the insulation reaction time is 2-12 hours.

[0018] Furthermore, in step S3, the cationic etherifying agent is one or more of 3-chloro-2-hydroxypropyltrimethylammonium chloride, 3-chloro-2-hydroxypropyltriethylammonium chloride, and 2,3-epoxypropyltrimethylammonium chloride.

[0019] Furthermore, in step S5, the dispersant is one or more of dispersant NNO, sodium polyacrylate dispersant, and quaternary ammonium salt dispersant.

[0020] Furthermore, in step S5, the fourth temperature is 85-95° C., and the insulation time is 1-5 hours.

[0021] Furthermore, the charge density of the prepared high charge density AKD emulsifier is 179-187 meq / g.

[0022] The beneficial effects of the present invention are:

[0023] (1) The preparation method of the high charge density AKD emulsifier provided by the present invention uses water as a solvent to disperse fresh cassava starch, which is energy-saving and environmentally friendly, does not cause secondary pollution, and the produced product can be directly used for the emulsification of AKD;

[0024] (2) The method for preparing the high charge density AKD emulsifier provided by the present invention first uses an oxidant to oxidize the cassava starch solution to degrade the residual protein in the starch, etc., which can effectively improve the stability of the starch slurry;

[0025] (3) The method for preparing the high charge density AKD emulsifier provided by the present invention is to first oxidize the cassava starch and then etherify it, thereby avoiding the influence of the subsequent oxidant on the etherified starch and improving the charge density of the prepared emulsifier;

[0026] (4) The AKD emulsifier prepared by the present invention has high charge density, stable product quality, and excellent AKD emulsification performance. When used in paper, it can play the role of colloid protection and retention and synergistic effect. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments 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 creative work should fall within the scope of protection of the present invention.

[0028] Example 1

[0029] A method for preparing an emulsifier for high charge density AKD comprises the following steps:

[0030] (1) In a 1444 ml three-necked flask with a mechanical stirring device and a condensation reflux tube, 244 g of water was added, and 244 g of fresh tapioca starch was added to the water under stirring at room temperature, and stirred for 14 to 24 minutes to fully disperse the tapioca starch to obtain an aqueous solution;

[0031] (2) adding 12.4 g of sodium hypochlorite solution to the aqueous solution of tapioca starch, adjusting the pH value to 8.5-9.5, cooling the reaction solution to control the temperature to 15-24° C., and keeping the temperature for 4 hours;

[0032] (3) The reaction solution was heated to 44°C, 24 g of liquid caustic soda was added until the pH value reached 11.4 to 13.4, the temperature was raised to 54°C, 144 g of 3-chloro-2-hydroxypropyltriethylammonium chloride was added, and the reaction was kept warm for 12 hours;

[0033] (4) After the reaction solution is kept warm, 16 g of glacial acetic acid is added, and the mixture is kept warm for 9 hours.

[0034] (5) After the reaction solution was kept warm for reaction, 6 g of dispersant NNO was added, the temperature was raised to 95° C. and kept warm for 5 hours, and water was added to adjust the content to obtain an emulsifier for AKD with a solid content of 34.18%.

[0035] Example 2

[0036] A method for preparing an emulsifier for high charge density AKD comprises the following steps:

[0037] (1) In a 1444 ml three-necked flask with a mechanical stirring device and a condensation reflux tube, 244 g of water was added, and 244 g of fresh tapioca starch was added to the water under stirring at room temperature, and stirred for 14 to 24 minutes to fully disperse the tapioca starch to obtain an aqueous solution;

[0038] (2) adding 12.4 g of sodium hypochlorite solution to the aqueous solution of cassava starch, adjusting the pH value to 8.5-9.5, cooling the reaction solution to a temperature of 15-24° C., and keeping the temperature for 4 hours;

[0039] (3) The reaction solution was heated to 74° C., 18 g of liquid caustic soda was added until the pH value reached 11.6, and the temperature was raised to 84° C., 94 g of 3-chloro-2-hydroxypropyltrimethylammonium chloride was added, and the reaction was kept warm for 2 hours;

[0040] (4) After the reaction solution was kept warm, 19 g of oxalic acid was added, and the reaction was kept warm for 9 hours after the addition was completed;

[0041] (5) After the reaction solution was kept warm for reaction, 4 g of quaternary ammonium salt dispersant was added, the temperature was raised to 85° C. and kept warm for 3 hours, and water was added to adjust the content to obtain an emulsifier for AKD with a solid content of 29.19%.

[0042] Example 3

[0043] A method for preparing an emulsifier for high charge density AKD comprises the following steps:

[0044] (1) In a 1444 ml three-necked flask with a mechanical stirring device and a condensation reflux tube, 244 g of water was added, and 244 g of fresh tapioca starch was added to the water under stirring at room temperature, and stirred for 14 to 24 minutes to fully disperse the tapioca starch to obtain an aqueous solution;

[0045] (2) adding 12.4 g of sodium hypochlorite solution to the aqueous solution of tapioca starch, adjusting the pH value to 8.5-9.5, cooling the reaction solution to control the temperature to 15-24° C., and keeping the temperature for 4 hours;

[0046] (3) The reaction solution was heated to 64° C., 19 g of liquid caustic soda was added until the pH value reached 12.5, the temperature was raised to 74° C., 78 g of glycidyltrimethylammonium chloride was added, and the reaction was kept warm for 8 hours;

[0047] (4) After the reaction solution is kept warm, 28 g of 31% hydrochloric acid is added. After the addition is complete, the reaction is kept warm for 9 hours.

[0048] (5) After the reaction solution was kept warm for reaction, 3 g of quaternary ammonium salt dispersant was added, the temperature was raised to 94° C. and kept warm for 1 hour, and water was added to adjust the content to obtain an emulsifier for AKD with a solid content of 32%.

[0049] Comparative Example 1

[0050] Comparative Example 1 is different from Example 1 in that the preparation method does not include step (2) in Example 1, and the specific steps are:

[0051] (1) In a 1444 ml three-necked flask with a mechanical stirring device and a condensation reflux tube, 244 g of water was added, and 244 g of fresh tapioca starch was added to the water under stirring at room temperature, and stirred for 14 to 24 minutes to fully disperse the tapioca starch to obtain an aqueous solution;

[0052] (2) heating the aqueous solution of tapioca starch to 44° C., adding 24 g of liquid caustic soda until the pH value reaches 11.4 to 13.4, heating the aqueous solution to 54° C., adding 144 g of 3-chloro-2-hydroxypropyltriethylammonium chloride, and keeping the temperature for reaction for 12 hours;

[0053] (3) After the reaction solution is kept warm, 16 g of glacial acetic acid is added, and the mixture is kept warm for 9 hours.

[0054] (4) After the reaction mixture was kept warm for reaction, 6 g of dispersant NNO was added, the temperature was raised to 95° C. and kept warm for 5 hours, and water was added to adjust the content to obtain an emulsifier for AKD.

[0055] Comparative Example 2

[0056] Comparative Example 2 is different from Example 1 in that the preparation method is first etherified and then oxidized, and the specific steps are:

[0057] (1) In a 1444 ml three-necked flask with a mechanical stirring device and a condensation reflux tube, 244 g of water was added, and 244 g of fresh tapioca starch was added to the water under stirring at room temperature, and stirred for 14 to 24 minutes to fully disperse the tapioca starch to obtain an aqueous solution;

[0058] (2) heating the aqueous solution of tapioca starch to 44° C., adding 24 g of liquid caustic soda until the pH value reaches 11.4 to 13.4, heating the aqueous solution to 54° C., adding 144 g of 3-chloro-2-hydroxypropyltriethylammonium chloride, and keeping the temperature for reaction for 12 hours;

[0059] (3) adding 12.4 g of sodium hypochlorite solution to the aqueous solution of tapioca starch, adjusting the pH value to 8.5-9.5, cooling the reaction solution to a temperature of 15-24° C., and keeping the temperature for 4 hours;

[0060] (4) After the reaction solution was kept warm, 16 g of glacial acetic acid was added, and the mixture was kept warm for 9 hours.

[0061] (5) After the reaction mixture was kept warm for reaction, 6 g of dispersant NNO was added, the temperature was raised to 95° C. and kept warm for 5 hours, and water was added to adjust the content to obtain an emulsifier for AKD.

[0062] The performance indicators of the emulsifiers for AKD prepared in various embodiments and comparative examples of the present invention are shown in Table 1.

[0063] Table 1 Performance indexes of emulsifiers for AKD prepared in various embodiments and comparative examples of the present invention

[0064] index Example 1 Comparative Example 1 Comparative Example 2 Example 2 Example 3 pH 4.18 4.66 4.41 3.28 4.56 Viscosity, mPa.s 127.4 144.3 94.24 85.4 49.4 Solid content, % 34.18％ 26.31％ 24.13％ 29.19％ 32％ Charge density, meq / g 186.9 98.1 89.32 179.6 185.3

[0065] It can be seen from Table 1 that the emulsifier for AKD prepared in the present invention has a higher charge density than that of the comparative example, improves the bonding strength with AKD particles, and plays a role in helping retention and enhancing efficiency.

[0066] The emulsifiers prepared in the above examples 1-3 were used to emulsify AKD, and the emulsification process was as follows: 54 grams of AKD and 84 grams of emulsifier were mixed, and then high-speed shearing (rotation speed 2444-5444 r / min) was performed for 14-24 minutes, and then homogenized using a high-pressure homogenizer, and appropriate water was added to dilute to obtain an AKD emulsion. The three AKD emulsions were subjected to a stability test in a 54°C constant temperature aging box, and the three AKD emulsions were placed in the aging test box for 7 days without stratification or demulsification.

[0067] Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and such modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily conceive of changes or substitutions within the technical scope disclosed by the present invention, and such changes or substitutions shall be within the scope of protection of the present invention.

Claims

1. A method for preparing an emulsifier for high charge density AKD, characterized in that: The steps include: S1, preparing an aqueous solution of tapioca starch; S2, adding an oxidant to the aqueous solution of cassava starch, adjusting the pH value of the system, and keeping the reaction at a first temperature; S3, after the reaction of step S2 is completed, the temperature is raised to the second temperature, an alkali solution is added, the temperature is raised to the third temperature, a cationic etherifying agent is added, and the temperature is kept for reaction; S4, adding acid to the reaction system in step S3 to terminate the reaction; S5, adding a dispersant to the reaction product of step S4, heating to a fourth temperature, keeping the temperature and then cooling to obtain a finished product; In step S2, the aqueous solution of tapioca starch begins to cool down when the oxidant is added, and the first temperature is 15-24° C.; In step S2, the oxidant is sodium hypochlorite; In step S2, the pH value of the system is adjusted to 8.5-9.5; In step S3, the second temperature is 40-70°C, the third temperature is 50-80°C, and the insulation reaction time is 2-12 hours; In step S3, the cationic etherifying agent is 3-chloro-2-hydroxypropyltriethylammonium chloride; The charge density of the prepared high charge density AKD emulsifier is 179~187meq / g; In step S5, the dispersant is dispersant NNO; In step S5, the fourth temperature is 85-95° C., and the insulation time is 1-5 hours.