CN111705539A - Preparation method of papermaking reinforcing agent - Google Patents
Preparation method of papermaking reinforcing agent Download PDFInfo
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- CN111705539A CN111705539A CN202010648748.8A CN202010648748A CN111705539A CN 111705539 A CN111705539 A CN 111705539A CN 202010648748 A CN202010648748 A CN 202010648748A CN 111705539 A CN111705539 A CN 111705539A
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
- D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
- D21H21/18—Reinforcing agents
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F251/00—Macromolecular compounds obtained by polymerising monomers on to polysaccharides or derivatives thereof
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- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08H—DERIVATIVES OF NATURAL MACROMOLECULAR COMPOUNDS
- C08H6/00—Macromolecular compounds derived from lignin, e.g. tannins, humic acids
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08H—DERIVATIVES OF NATURAL MACROMOLECULAR COMPOUNDS
- C08H8/00—Macromolecular compounds derived from lignocellulosic materials
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/20—Macromolecular organic compounds
- D21H17/21—Macromolecular organic compounds of natural origin; Derivatives thereof
- D21H17/23—Lignins
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/20—Macromolecular organic compounds
- D21H17/21—Macromolecular organic compounds of natural origin; Derivatives thereof
- D21H17/24—Polysaccharides
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/20—Macromolecular organic compounds
- D21H17/33—Synthetic macromolecular compounds
- D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/20—Macromolecular organic compounds
- D21H17/33—Synthetic macromolecular compounds
- D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- D21H17/37—Polymers of unsaturated acids or derivatives thereof, e.g. polyacrylates
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
- D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
- D21H21/18—Reinforcing agents
- D21H21/20—Wet strength agents
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Abstract
The invention discloses a preparation method of a papermaking reinforcing agent, and belongs to the technical field of preparation of papermaking additives. Decomposing straw residues with strong alkali liquor, filtering to extract an immersion liquid containing a large amount of lignin, cationizing with 2, 3-epoxypropyltrimethylammonium chloride, adjusting to be neutral, centrifugally precipitating and drying to obtain a cationic dispersant, reacting orthophosphate with the esterification of orthophosphate through the reaction of pyrophosphate as an intermediate, decomposing the two orthophosphates into pyrophosphate when being heated, reacting the generated pyrophosphate with starch light base to obtain starch phosphate, grafting acrylamide monomer with the starch phosphate as a matrix to obtain a starch phosphate graft, exerting the synergistic effect of the starch phosphate graft and effectively improving the wet strength and the dry strength of paper; according to the invention, the cationic dispersant prepared by taking the straw residues as the raw material is a lignin cationization product, and the lignin has a larger spatial structure, so that larger steric hindrance can be generated in the papermaking reinforcing agent, and the dispersion performance of particles in the papermaking reinforcing agent is improved.
Description
Technical Field
The invention discloses a preparation method of a papermaking reinforcing agent, and belongs to the technical field of preparation of papermaking additives.
Background
The paper-making industry in China is in a high-speed development stage, and because of the shortage of wood resources in China, the paper-making industry currently adopts grass and waste paper to recycle pulp and make paper. However, the use of grass and waste paper raw materials and fillers can cause strength loss, and the use of paper reinforcing agents can solve these problems in order to meet the demand of people for high-grade paper. The paper strengthening agent is a fine chemical for strengthening the strength of paper and paperboard, and is mainly used in the paper production process to improve the strength and tear resistance of paper made of straw pulp and waste paper.
The reinforcing agents can be divided into dry-strengthening agents and wet-strengthening agents according to different effects, wherein the dry-strengthening agents and the wet-strengthening agents belong to internal reinforcing agents, and the reinforcing mechanisms of the internal reinforcing agents are different.
Dry strength agents are fine chemicals used to improve the bonding between fibers to increase the physical strength (tensile strength, tear strength, burst strength, etc.) of paper without affecting its wet strength. In general, polymers which are soluble in water and which carry hydrogen bonds are suitable as dry strength aids. In fact, wood fibers contain hemicellulose, a natural dry strength agent. The hydrogen bonding and electrostatic adsorption between fibers are the reasons for the dry strength of paper, and particularly, the hydrogen bonding points are many, the bonding force is strong, and the dry strength is mainly caused. Common dry strength agents are starch derivatives (about 95% of the total amount), mainly cationic starch, amphoteric starch, and the like. The starch used in the paper industry is mostly modified starch, and the amount of the starch is almost 80-90% of the total amount of the paper-making chemicals.
The mechanical strength of paper and paperboard is almost completely lost after being soaked in water, and generally only 4-10% of the dry paper strength can be maintained, while some special papers such as photographic base paper, blueprint base paper, military ground paper, banknote paper and the like not only have certain dry strength requirements, but also still can maintain certain mechanical strength and characteristics after being soaked in water, and therefore, a wet strength agent is required to be added to improve the wet strength of the paper. Wet strength is the ability of paper to retain some mechanical strength and properties after it has been saturated with water. After the wet strength agent is added, the wet strength of the paper can reach 20-40% of the original dry strength.
The polyethyleneimine is the cationic wet strength agent which is most applied and has a well-known effect at present, and the molecular chain of the polyethyleneimine contains a plurality of cationic groups, so that the polyethyleneimine can generate strong electrostatic adsorption with hydroxyl on cellulose to form a secondary valence crosslinking network.
At present, most of papermaking reinforcing agents on the market have single function, for example, modified starch can only be used for dry strength agents; high molecular polymers such as polyethyleneimine, urea-formaldehyde resin, melamine-formaldehyde resin and the like are used for the wet strength agent, and most of the high molecular polymers are toxic and are not suitable for being used in large quantities. The requirement of having both dry strength and wet strength cannot be met.
The aqueous solution polymerization process is simple, the polymerization yield is high, the environmental pollution is less, and the method is the preferred method for preparing the organic polymer. Aqueous solution polymerization has many advantages, but also has many disadvantages, and it is difficult to prepare a high-molecular-weight polymer having a high solid content. The utilization rate is low, the liquid product has high viscosity and poor fluidity, and the problems can be effectively solved by inverse emulsion, inverse suspension, precipitation polymerization and the like. However, the use of a large amount of organic solvent causes problems such as pollution and production cost, and the water solubility of the product is poor, which makes the use of the product very difficult.
Therefore, the invention of a papermaking reinforcing agent which has dry strength and wet strength and good fluidity is necessary for the technical field of preparation of papermaking additives.
Disclosure of Invention
The invention mainly solves the technical problem, and provides a preparation method of a papermaking reinforcing agent aiming at the defects that the conventional papermaking reinforcing agent is difficult to have double functions of a dry reinforcing agent and a wet reinforcing agent, solid particles in a reinforcing agent liquid product have poor water solubility and low utilization rate, and the liquid product has high viscosity and poor liquidity.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
the preparation method of the papermaking reinforcing agent comprises the following steps:
adding the starch phosphate graft and deionized water into a stirring kettle, stirring to be homogeneous, adding a low-molecular-weight cross-linking material and a cationic dispersant, adjusting the pH to 5.5-6.0 by using an acetic acid solution with the mass fraction of 50%, and adding water for dilution to obtain a papermaking reinforcing agent;
the preparation method of the cationic dispersant comprises the following specific steps:
putting 40-50 parts by weight of straw residues and 100-120 parts by weight of a 30% sodium hydroxide solution into a water bath reaction kettle with a stirrer, heating in a water bath to 70-80 ℃, starting the stirrer, stirring for 3-5 hours, filtering to remove filter residues, adding 2, 3-epoxypropyltrimethylammonium chloride into filtrate, stirring for reaction for 20-25 min, regulating the filtrate to be neutral by using 95% glacial acetic acid, performing centrifugal treatment, washing precipitates obtained by centrifugation for 2-3 times by using water, then transferring the precipitates into an oven with the set temperature of 70-80 ℃, and drying for 4-5 hours to obtain a cationic dispersant;
the starch phosphate graft specifically comprises the following preparation steps:
(1) adding starch and 20 mass percent sodium dihydrogen phosphate solution into a beaker, stirring for 10-15 min at room temperature, adding urea, heating to 45-50 ℃ in a water bath, reacting for 3-4 h under heat preservation, filtering to remove filtrate, and drying the precipitate in an oven at a set temperature of 50-55 ℃ for 4-5 h to obtain starch phosphate;
(2) adding the starch phosphate and water into a three-neck flask of a condensation reflux device, heating the mixture to 50-60 ℃ in a water bath, stirring the mixture for 4-5 min at a constant temperature, adding an acrylamide monomer, adding an initiator, introducing nitrogen for protection, reacting the mixture for 1-2 h under a heat preservation condition, then pouring out a reaction solution, and air-drying the reaction solution at normal temperature to obtain a starch phosphate graft;
the preparation method of the low molecular weight cross-linked polymer comprises the following specific steps:
(1) adding 20-25 parts by weight of chitosan and 40-50 parts by weight of 2% acetic acid solution into a four-neck flask, stirring for 4-5 min, adding 30-35 parts by weight of 30% formaldehyde aqueous solution and 40-45 parts by weight of polyacrylamide, heating to 60-80 ℃, and reacting for 2-3 h to obtain a cross-linked substance;
(2) dialyzing the cross-linked product with distilled water to obtain a dialyzed reaction product, placing the dialyzed reaction product in a rotary evaporator, carrying out rotary evaporation at the rotating speed of 80-90 r/min for 20-25 min to obtain a rotary evaporation product, and then carrying out freeze drying at the temperature of-40 to-20 ℃ for 30-35 min to obtain the low-molecular-weight cross-linked product.
The papermaking reinforcing agent comprises the main components in the specific preparation steps of 40-50 parts by weight of starch phosphate graft, 30-40 parts by weight of low molecular weight cross-linking material and 20-25 parts by weight of cationic dispersant.
The viscosity of the papermaking reinforcing agent obtained after the papermaking reinforcing agent is diluted by water in the specific preparation step is 100-120 mPa & s.
In the specific preparation step of the cationic dispersant, the addition amount of 2, 3-epoxypropyltrimethylammonium chloride is 4-5% of the mass of the filtrate.
The starch phosphate graft is prepared by the following raw materials in part by weight in the step (1), wherein the raw materials comprise 40-45 parts of starch, 60-70 parts of sodium dihydrogen phosphate solution with the mass fraction of 20% and 5-10 parts of urea.
The starch phosphate graft specifically comprises, in the step (2), 5-6 parts of starch phosphate, 100-110 parts of water, 10-15 parts of acrylamide monomer and 4-5 parts of initiator by weight.
The initiator in the specific preparation step (2) of the starch phosphate graft is obtained by dissolving 1g of ammonium ceric nitrate in 50mL of nitric acid solution with the concentration of 1 mol/L.
The polyacrylamide in the specific preparation step (1) of the low molecular weight cross-linked substance is preferably anionic polyacrylamide.
The molecular weight cut-off of the low molecular weight cross-linking substance is controlled to be below 500KD in the dialysis process in the specific preparation step (2).
The invention has the beneficial effects that:
(1) the invention decomposes straw residue with strong alkali liquor, extracts immersion liquid containing a large amount of lignin by filtration, then carries out cationization with 2, 3-epoxypropyl trimethyl ammonium chloride, adjusts to be neutral, carries out centrifugal precipitation and drying to obtain cationic dispersant,
the method comprises the steps of utilizing esterification of orthophosphate, reacting through pyrophosphate as an intermediate, decomposing the orthophosphate into the pyrophosphate when the orthophosphate is heated, reacting the generated pyrophosphate with a starch light base to obtain starch phosphate, grafting an acrylamide monomer by using the starch phosphate as a matrix to obtain a starch phosphate graft, crosslinking anionic polyacrylamide and chitosan through a Mannich reaction principle to obtain a crosslinked substance, dialyzing to intercept the low-molecular-weight crosslinked substance, wherein the crosslinked substance is chitosan-anionic polyacrylamide, organically combining the reinforcement property of polyacrylamide and the reinforcement property of chitosan to play a synergistic effect, and effectively improving the wet strength of paper, and the starch phosphate graft belongs to a starch cationic derivative and can effectively improve the dry strength of the paper;
(2) the cationic dispersant prepared by taking straw residues as a raw material is a lignin cationization product, the lignin has a larger spatial structure, and can generate larger steric hindrance in a papermaking reinforcing agent, so that the improvement of the dispersion performance of particles in the papermaking reinforcing agent is facilitated, the liquid of the papermaking reinforcing agent is kept at uniform density and has good fluidity, the water solubility of solid particles can be improved by the anion of the prepared chitosan-anionic polyacrylamide cross-linked polymer, the viscosity of the reinforcing agent can be greatly reduced by the cross-linked polymer with low molecular weight, although the starch derivative is esterified, part of hydroxyl sites do not participate in the reaction, the starch derivative can also be dispersed in aqueous liquid, the utilization rate and the fluidity of the reinforcing agent liquid are improved, and the starch derivative has a wide application prospect.
Detailed Description
Putting 40-50 parts by weight of straw residues and 100-120 parts by weight of a 30% sodium hydroxide solution into a water bath reaction kettle with a stirrer, heating in a water bath to 70-80 ℃, starting the stirrer, stirring for 3-5 hours, filtering to remove filter residues, adding 4-5% by weight of 2, 3-epoxypropyltrimethylammonium chloride into the filtrate, stirring and reacting for 20-25 minutes, regulating the filtrate to be neutral by using 95% by weight of glacial acetic acid, centrifuging, washing the precipitate obtained by centrifuging for 2-3 times by using water, then transferring the precipitate into a drying oven with the set temperature of 70-80 ℃, and drying for 4-5 hours to obtain a cationic dispersant for later use; adding 40-45 parts of starch and 60-70 parts of 20% sodium dihydrogen phosphate solution into a beaker according to parts by weight, stirring for 10-15 min at room temperature, adding 5-10 parts of urea, heating to 45-50 ℃ in a water bath, reacting for 3-4 h at a constant temperature, filtering to remove filtrate, and drying the precipitate in an oven at a set temperature of 50-55 ℃ for 4-5 h to obtain starch phosphate; adding 5-6 parts of starch phosphate and 100-110 parts of water into a three-neck flask of a condensation reflux device according to parts by weight, heating the mixture in a water bath to 50-60 ℃, stirring the mixture at a constant temperature for 4-5 min, adding 10-15 parts of acrylamide monomer, adding an initiator, introducing nitrogen for protection, reacting the mixture after heat preservation for 1-2 h, then discharging a reaction solution, and drying the reaction solution at normal temperature to obtain a starch phosphate graft for later use, wherein the initiator is obtained by dissolving 1g of ammonium ceric nitrate in 50mL of nitric acid solution with the concentration of 1 mol/L. Adding 20-25 parts by weight of chitosan and 40-50 parts by weight of 2% acetic acid solution into a four-neck flask, stirring for 4-5 min, adding 30-35 parts by weight of 30% formaldehyde aqueous solution and 40-45 parts by weight of anionic polyacrylamide, heating to 60-80 ℃, and reacting for 2-3 h to obtain a cross-linked substance; dialyzing the cross-linked substance with distilled water, controlling the cut-off molecular weight to be below 500KD to obtain a dialyzed reaction product, placing the dialyzed reaction product in a rotary evaporator, carrying out rotary evaporation at the rotating speed of 80-90 r/min for 20-25 min to obtain a rotary evaporation product, and then carrying out freeze drying at the temperature of-40 to-20 ℃ for 30-35 min to obtain a low-molecular-weight cross-linked substance; adding 40-50 parts by weight of standby starch phosphate graft and 400-500 parts by weight of deionized water into a stirring kettle, stirring to a homogeneous phase, adding 30-40 parts by weight of the low molecular weight cross-linking material and 20-25 parts by weight of standby cationic dispersant, adjusting the pH to 5.5-6.0 by using an acetic acid solution with the mass fraction of 50%, and adding water to dilute until the viscosity is 100-120 mPa · s to obtain the papermaking reinforcing agent.
Example 1
Preparation of cationic dispersant:
putting 40 parts of straw residues and 100 parts of 30% sodium hydroxide solution by mass into a water bath reaction kettle with a stirrer, heating the mixture in a water bath to 70 ℃, starting the stirrer, stirring the mixture for 3 hours, filtering to remove filter residues, adding 4% of 2, 3-epoxypropyltrimethylammonium chloride by mass into the filtrate, stirring and reacting for 20 minutes, adjusting the mixture to be neutral by using 95% glacial acetic acid by mass, performing centrifugal treatment, washing the precipitate obtained by centrifugation with water for 2 times, transferring the precipitate into a drying oven with the set temperature of 70 ℃, and drying the precipitate for 4 hours to obtain a cationic dispersant for later use;
preparation of starch phosphate graft:
adding 40 parts of starch and 60 parts of 20% sodium dihydrogen phosphate solution into a beaker according to parts by weight, stirring for 10min at room temperature, adding 5 parts of urea, heating to 45 ℃ in a water bath, carrying out heat preservation reaction for 3h, filtering to remove filtrate, and drying the precipitate in an oven at a set temperature of 50 ℃ for 4h to obtain starch phosphate;
adding 5 parts of the starch phosphate and 100 parts of water into a three-neck flask of a condensation reflux device according to parts by weight, heating the mixture in a water bath to 50 ℃, stirring the mixture at a constant temperature for 4min, adding 10 parts of acrylamide monomer, adding an initiator, introducing nitrogen for protection, reacting the mixture for 1h under a heat preservation condition, then pouring out a reaction solution, and drying the reaction solution at a normal temperature to obtain a starch phosphate graft for later use, wherein the initiator is obtained by dissolving 1g of ammonium ceric nitrate in 50mL of nitric acid solution with the concentration of 1 mol/L.
Preparation of the papermaking reinforcing agent:
adding 20 parts by weight of chitosan and 40 parts by weight of 2% acetic acid solution into a four-neck flask, stirring for 4min, adding 30 parts by weight of 30% formaldehyde aqueous solution and 40 parts by weight of anionic polyacrylamide, heating to 60 ℃, and reacting for 2h to obtain a cross-linked substance;
dialyzing the cross-linked substance with distilled water, controlling the cut-off molecular weight to be below 500KD to obtain a dialyzed reaction product, placing the dialyzed reaction product in a rotary evaporator, carrying out rotary evaporation at the rotating speed of 80r/min for 20min to obtain a rotary evaporation product, and then carrying out freeze drying at the temperature of-40 ℃ for 30min to obtain a low-molecular-weight cross-linked substance;
adding 40 parts of standby starch phosphate graft and 400 parts of deionized water into a stirring kettle, stirring to be homogeneous, adding 30 parts of the low-molecular-weight cross-linking material and 20 parts of standby cationic dispersant, adjusting the pH to 5.5 by using an acetic acid solution with the mass fraction of 50%, and adding water to dilute until the viscosity is 100mPa & s to obtain the papermaking reinforcing agent.
Example 2
Preparation of cationic dispersant:
according to the weight parts, 45 parts of straw residues and 110 parts of sodium hydroxide solution with the mass fraction of 30% are placed into a water bath reaction kettle with a stirrer, the water bath is heated to 75 ℃, the stirrer is started to stir for 4 hours, filter residues are removed, 2, 3-epoxypropyltrimethylammonium chloride with the mass fraction of 4% of the filtrate is added into the filtrate, the mixture is stirred and reacted for 22 minutes, glacial acetic acid with the mass fraction of 95% is used for adjusting the mixture to be neutral, then centrifugal treatment is carried out, water is used for washing and centrifuging the obtained precipitate for 2 times, then the precipitate is moved into a drying oven with the set temperature of 75 ℃, and drying is carried out for 4.5 hours, so as to obtain a cationic dispersing agent for later use;
preparation of starch phosphate graft:
adding 42 parts of starch and 65 parts of 20% sodium dihydrogen phosphate solution into a beaker according to parts by weight, stirring at room temperature for 12min, adding 7 parts of urea, heating in a water bath to 47 ℃, carrying out heat preservation reaction for 3.5h, filtering to remove filtrate, and drying the precipitate in an oven with the set temperature of 52 ℃ for 4.5h to obtain starch phosphate;
adding 5 parts of the starch phosphate and 105 parts of water into a three-neck flask of a condensation reflux device according to parts by weight, heating the mixture in a water bath to 55 ℃, stirring the mixture at a constant temperature for 4min, adding 12 parts of acrylamide monomer, adding an initiator, introducing nitrogen for protection, reacting for 1.5h at a constant temperature, pouring out a reaction solution, and air-drying the reaction solution at normal temperature to obtain a starch phosphate graft for later use, wherein the initiator is obtained by dissolving 1g of ammonium ceric nitrate in 50mL of nitric acid solution with the concentration of 1 mol/L.
Preparation of the papermaking reinforcing agent:
adding 22 parts by weight of chitosan and 45 parts by weight of 2% acetic acid solution into a four-neck flask, stirring for 4min, adding 32 parts by weight of 30% formaldehyde aqueous solution and 42 parts by weight of anionic polyacrylamide, heating to 70 ℃, and reacting for 2.5h to obtain a cross-linked substance;
dialyzing the cross-linked substance with distilled water, controlling the cut-off molecular weight to be below 500KD to obtain a dialyzed reaction product, placing the dialyzed reaction product in a rotary evaporator, carrying out rotary evaporation for 22min at the rotating speed of 85r/min to obtain a rotary evaporation product, and then carrying out freeze drying for 32min at the temperature of-30 ℃ to obtain a low-molecular-weight cross-linked substance;
adding 45 parts of standby starch phosphate graft and 450 parts of deionized water into a stirring kettle, stirring to be homogeneous, adding 35 parts of the low-molecular-weight cross-linking material and 22 parts of standby cationic dispersant, adjusting the pH to 5.7 by using an acetic acid solution with the mass fraction of 50%, and adding water to dilute until the viscosity is 110mPa & s to obtain the papermaking reinforcing agent.
Example 3
Preparation of cationic dispersant:
putting 50 parts of straw residues and 120 parts of a sodium hydroxide solution with the mass fraction of 30% into a water bath reaction kettle with a stirrer, heating the mixture in a water bath to 80 ℃, starting the stirrer, stirring the mixture for 5 hours, filtering the mixture to remove filter residues, adding 2, 3-epoxypropyltrimethylammonium chloride with the mass fraction of 5% of the filtrate into the filtrate, stirring the mixture to react for 25 minutes, regulating the mixture to be neutral by using glacial acetic acid with the mass fraction of 95%, centrifuging the mixture, washing the precipitate obtained by centrifuging the precipitate for 3 times by using water, transferring the precipitate into a drying oven with the set temperature of 80 ℃, and drying the precipitate for 5 hours to obtain a cationic dispersant for later use;
preparation of starch phosphate graft:
adding 45 parts of starch and 70 parts of 20% sodium dihydrogen phosphate solution into a beaker according to parts by weight, stirring for 15min at room temperature, adding 10 parts of urea, heating to 50 ℃ in a water bath, carrying out heat preservation reaction for 4h, filtering to remove filtrate, and drying the precipitate in an oven at a set temperature of 55 ℃ for 5h to obtain starch phosphate;
adding 6 parts of the starch phosphate and 110 parts of water into a three-neck flask of a condensation reflux device according to parts by weight, heating the mixture in a water bath to 60 ℃, stirring the mixture at a constant temperature for 5min, adding 15 parts of acrylamide monomer, adding an initiator, introducing nitrogen for protection, reacting the mixture after 2h of heat preservation, then pouring out a reaction solution, and drying the reaction solution at normal temperature to obtain a starch phosphate graft for later use, wherein the initiator is obtained by dissolving 1g of ammonium ceric nitrate in 50mL of nitric acid solution with the concentration of 1 mol/L.
Preparation of the papermaking reinforcing agent:
adding 25 parts by weight of chitosan and 50 parts by weight of 2% acetic acid solution into a four-neck flask, stirring for 5min, adding 35 parts by weight of 30% formaldehyde aqueous solution and 45 parts by weight of anionic polyacrylamide, heating to 80 ℃, and reacting for 3h to obtain a cross-linked substance;
dialyzing the cross-linked substance with distilled water, controlling the cut-off molecular weight to be below 500KD to obtain a dialyzed reaction product, placing the dialyzed reaction product in a rotary evaporator, carrying out rotary evaporation at the rotating speed of 90r/min for 25min to obtain a rotary evaporation product, and then carrying out freeze drying at the temperature of-20 ℃ for 35min to obtain a low-molecular-weight cross-linked substance;
adding 50 parts by weight of standby starch phosphate graft and 500 parts by weight of deionized water into a stirring kettle, stirring to be homogeneous, adding 40 parts by weight of the low molecular weight cross-linking material and 25 parts by weight of standby cationic dispersant, adjusting the pH to 6.0 by using an acetic acid solution with the mass fraction of 50%, and adding water to dilute until the viscosity is 120mPa · s to obtain the papermaking reinforcing agent.
Comparative example 1: essentially the same procedure as in example 2 was followed except that the cationic dispersant was absent.
Comparative example 2: essentially the same procedure as in example 2 was followed except that the starch phosphate graft was absent.
Comparative example 3: a paper strengthening agent manufactured by a company of Guangzhou city.
The viscosity was measured with a rotor viscometer.
Water soluble type test: 10g of sample is taken, 200 g of water is added, the sample is soaked for 15min, a magnetic stirrer is used for stirring for 5min at the speed of 100r/min, and whether the sample is completely dissolved or not is observed.
And (3) testing the strength: the reinforcing agents for papermaking in examples and comparative examples were used in papermaking, and after drying, they were allowed to equilibrate at standard temperature and humidity conditions for 24 hours, and their tensile strength, folding endurance, and burst index were measured.
Table 1: results of measurement of Performance of papermaking reinforcing agent
| Detecting items | Example 1 | Example 2 | Example 3 | Comparative example 1 | Comparative example 2 | Comparative example 3 |
| Folding endurance (second) | 8 | 9 | 10 | 4 | 5 | 7 |
| Tensile Strength (kg/15 mm) | 10.3 | 10.5 | 10.6 | 5.2 | 6.3 | 6.5 |
| Burst index (kPa.m)2/g） | 1.87 | 1.90 | 1.92 | 1.23 | 1.32 | 1.44 |
| Viscosity (Pa s) | 5.5 | 5.2 | 5.0 | 7.5 | 7.8 | 6.9 |
| Water solubility | Completely dissolve | Completely dissolve | Completely dissolve | Is not completely dissolved | Is not completely dissolved | Is not completely dissolved |
In summary, it can be seen from table 1 that the papermaking reinforcing agent of the present invention has low viscosity, good fluidity, good water solubility, high utilization rate, high dry strength and wet strength, and has a wide application prospect.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, but rather as the subject matter of the invention is to be construed in all aspects and as broadly as possible, and all changes, equivalents and modifications that fall within the true spirit and scope of the invention are therefore intended to be embraced therein.
Claims (9)
1. A preparation method of a papermaking reinforcing agent is characterized by comprising the following specific preparation steps:
adding the starch phosphate graft and deionized water into a stirring kettle, stirring to be homogeneous, adding a low-molecular-weight cross-linking material and a cationic dispersant, adjusting the pH to 5.5-6.0 by using an acetic acid solution with the mass fraction of 50%, and adding water for dilution to obtain a papermaking reinforcing agent;
the preparation method of the cationic dispersant comprises the following specific steps:
putting 40-50 parts by weight of straw residues and 100-120 parts by weight of a 30% sodium hydroxide solution into a water bath reaction kettle with a stirrer, heating in a water bath to 70-80 ℃, starting the stirrer, stirring for 3-5 hours, filtering to remove filter residues, adding 2, 3-epoxypropyltrimethylammonium chloride into filtrate, stirring for reaction for 20-25 min, regulating the filtrate to be neutral by using 95% glacial acetic acid, performing centrifugal treatment, washing precipitates obtained by centrifugation for 2-3 times by using water, then transferring the precipitates into an oven with the set temperature of 70-80 ℃, and drying for 4-5 hours to obtain a cationic dispersant;
the starch phosphate graft specifically comprises the following preparation steps:
(1) adding starch and 20 mass percent sodium dihydrogen phosphate solution into a beaker, stirring for 10-15 min at room temperature, adding urea, heating to 45-50 ℃ in a water bath, reacting for 3-4 h under heat preservation, filtering to remove filtrate, and drying the precipitate in an oven at a set temperature of 50-55 ℃ for 4-5 h to obtain starch phosphate;
(2) adding the starch phosphate and water into a three-neck flask of a condensation reflux device, heating the mixture to 50-60 ℃ in a water bath, stirring the mixture for 4-5 min at a constant temperature, adding an acrylamide monomer, adding an initiator, introducing nitrogen for protection, reacting the mixture for 1-2 h under a heat preservation condition, then pouring out a reaction solution, and air-drying the reaction solution at normal temperature to obtain a starch phosphate graft;
the preparation method of the low molecular weight cross-linked polymer comprises the following specific steps:
(1) adding 20-25 parts by weight of chitosan and 40-50 parts by weight of 2% acetic acid solution into a four-neck flask, stirring for 4-5 min, adding 30-35 parts by weight of 30% formaldehyde aqueous solution and 40-45 parts by weight of polyacrylamide, heating to 60-80 ℃, and reacting for 2-3 h to obtain a cross-linked substance;
(2) dialyzing the cross-linked product with distilled water to obtain a dialyzed reaction product, placing the dialyzed reaction product in a rotary evaporator, carrying out rotary evaporation at the rotating speed of 80-90 r/min for 20-25 min to obtain a rotary evaporation product, and then carrying out freeze drying at the temperature of-40 to-20 ℃ for 30-35 min to obtain the low-molecular-weight cross-linked product.
2. The method for preparing a papermaking reinforcing agent according to claim 1, wherein: the papermaking reinforcing agent comprises the main components in the specific preparation steps of 40-50 parts by weight of starch phosphate graft, 30-40 parts by weight of low molecular weight cross-linking material and 20-25 parts by weight of cationic dispersant.
3. The method for preparing a papermaking reinforcing agent according to claim 1, wherein: the viscosity of the papermaking reinforcing agent obtained after the papermaking reinforcing agent is diluted by water in the specific preparation step is 100-120 mPa & s.
4. The method for preparing a papermaking reinforcing agent according to claim 1, wherein: in the specific preparation step of the cationic dispersant, the addition amount of 2, 3-epoxypropyltrimethylammonium chloride is 4-5% of the mass of the filtrate.
5. The method for preparing a papermaking reinforcing agent according to claim 1, wherein: the starch phosphate graft is prepared by the following raw materials in part by weight in the step (1), wherein the raw materials comprise 40-45 parts of starch, 60-70 parts of sodium dihydrogen phosphate solution with the mass fraction of 20% and 5-10 parts of urea.
6. The method for preparing a papermaking reinforcing agent according to claim 1, wherein: the starch phosphate graft specifically comprises, in the step (2), 5-6 parts of starch phosphate, 100-110 parts of water, 10-15 parts of acrylamide monomer and 4-5 parts of initiator by weight.
7. The method for preparing a papermaking reinforcing agent according to claim 1, wherein: the initiator in the specific preparation step (2) of the starch phosphate graft is obtained by dissolving 1g of ammonium ceric nitrate in 50mL of nitric acid solution with the concentration of 1 mol/L.
8. The method for preparing a papermaking reinforcing agent according to claim 1, wherein: the polyacrylamide in the specific preparation step (1) of the low molecular weight cross-linked substance is preferably anionic polyacrylamide.
9. The method for preparing a papermaking reinforcing agent according to claim 1, wherein: the molecular weight cut-off of the low molecular weight cross-linking substance is controlled to be below 500KD in the dialysis process in the specific preparation step (2).
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116535671A (en) * | 2023-05-06 | 2023-08-04 | 中联煤层气(山西)有限责任公司 | Environment-friendly salt-resistant calcium-resistant high-temperature-resistant filtrate reducer and preparation method and application thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116535671A (en) * | 2023-05-06 | 2023-08-04 | 中联煤层气(山西)有限责任公司 | Environment-friendly salt-resistant calcium-resistant high-temperature-resistant filtrate reducer and preparation method and application thereof |
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