CN112409521A - Film coating agent and preparation method and application thereof - Google Patents
Film coating agent and preparation method and application thereof Download PDFInfo
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- CN112409521A CN112409521A CN202011353220.4A CN202011353220A CN112409521A CN 112409521 A CN112409521 A CN 112409521A CN 202011353220 A CN202011353220 A CN 202011353220A CN 112409521 A CN112409521 A CN 112409521A
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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
- D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
- D21H27/002—Tissue paper; Absorbent paper
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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
- C08F210/00—Copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
- C08F210/02—Ethene
-
- 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
- C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
- C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
- C08F220/04—Acids; Metal salts or ammonium salts thereof
- C08F220/06—Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/12—Powdering or granulating
- C08J3/126—Polymer particles coated by polymer, e.g. core shell structures
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/12—Powdering or granulating
- C08J3/128—Polymer particles coated by inorganic and non-macromolecular organic compounds
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F11/00—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines
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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
- D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
-
- 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
- D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
- D21H11/12—Pulp from non-woody plants or crops, e.g. cotton, flax, straw, bagasse
-
- 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
- D21H19/00—Coated paper; Coating material
- D21H19/10—Coatings without pigments
- D21H19/14—Coatings without pigments applied in a form other than the aqueous solution defined in group D21H19/12
- D21H19/20—Coatings without pigments applied in a form other than the aqueous solution defined in group D21H19/12 comprising 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
- 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
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2333/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers
- C08J2333/02—Homopolymers or copolymers of acids; Metal or ammonium salts thereof
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/34—Silicon-containing compounds
- C08K3/36—Silica
Abstract
The invention relates to a coating agent and a preparation method and application thereof. The method comprises the following steps: mixing 5-30 parts by weight of acrylic acid and 10-80 parts by weight of ethylene under the pressure of 2-5 MPa, and adding 0.2-1 part by weight of azobisisobutyronitrile to obtain a reaction solution; and reacting the reaction solution for 1-3 hours under the conditions that the pressure is 2-5 MPa and the temperature is 40-80 ℃ to prepare the coating agent. When the film coating agent prepared by the method is applied to the preparation of the water-absorbent resin for manufacturing the water-absorbent paper by a wet method, a layer of film coating (semi-hydrophilic film) for adjusting the water absorption capacity of SAP particles is added on the surface of the traditional super-absorbent resin, and the semi-hydrophilic protective film can absorb a small amount of water and temporarily prevent SAP cores from absorbing water, so that the water absorption performance of the SAP cores is ensured, and ions and impurities in paper pulp can be prevented from entering the SAP cores, and the SAP performance can be furthest kept.
Description
The application is a divisional application of an invention patent application with the application date of '20/11/2019', the application number of '201911138136.8', and the invention name of 'a water-absorbent resin for manufacturing water-absorbent paper by a wet method and a preparation method thereof'.
Technical Field
The invention relates to the field of functional polymeric chemical additives, in particular to a coating agent and a preparation method and application thereof.
Background
The high water-absorbent resin is widely applied to the preparation of absorbent paper due to better water absorption and retention capacity, the manufacturing methods of the absorbent paper on the market are dry compounding methods at present, namely, glue is sprayed on the surface of a wood pulp layer, and then the high water-absorbent resin is dispersed on the surface of the wood pulp paper layer.
Chinese patent application CN201710966882.0 discloses a method for making absorbent material by wet-process composite high molecular absorbent resin, i.e. adding high molecular absorbent resin in the early stage of wood pulp paper layer formation, which can greatly increase the contact area between high molecular absorbent resin and paper fiber, and enhance the liquid conductivity between paper fiber and high molecular absorbent resin, thereby greatly increasing the liquid absorption capacity and absorption speed of absorbent material (absorbent paper). However, since the conventional super absorbent resin has strong hydrophilicity, when the conventional super absorbent resin is applied to wet papermaking, a large amount of liquid is absorbed in the mixing process with paper pulp, and after drying, the performance of the high polymer water absorbent resin (SAP) is seriously reduced, and when the conventional super absorbent resin is applied to a preparation process for manufacturing absorbent paper by a wet method, the problems that the absorption properties such as water retention rate, liquid permeability and the like of the high polymer water absorbent resin after wet processing are seriously reduced exist.
Disclosure of Invention
In order to solve the technical problems in the prior art, the invention provides a coating agent and a preparation method and application thereof. When the film coating agent prepared by the method is applied to the preparation of the water-absorbent resin for manufacturing the water-absorbent paper by a wet method, a layer of film coating (semi-hydrophilic film) for adjusting the water absorption capacity of SAP particles is added on the surface of the traditional super-absorbent resin, and the semi-hydrophilic protective film can absorb a small amount of water and temporarily prevent SAP cores from absorbing water, so that the water absorption performance of the SAP cores is ensured, and ions and impurities in paper pulp can be prevented from entering the SAP cores, and the SAP performance can be furthest kept.
The invention provides a preparation method of a film coating agent, which comprises the following steps:
(a) mixing 5-30 parts by weight of acrylic acid and 10-80 parts by weight of ethylene under the pressure of 2-5 MPa, and adding 0.2-1 part by weight of azobisisobutyronitrile to obtain a reaction solution;
(b) and (b) reacting the reaction solution obtained in the step (a) for 1-3 hours under the conditions that the pressure is 2-5 MPa and the temperature is 40-80 ℃ to obtain the coating agent.
Preferably, in the step (b), the reaction solution obtained in the step (a) reacts for 2 hours under the conditions that the pressure is 3-5 MPa and the temperature is 50 ℃ to prepare the film coating agent.
The invention also provides a film coating agent prepared by the preparation method of the film coating agent.
The invention also provides application of the coating agent prepared by the preparation method of the coating agent in preparation of the water-absorbent resin for manufacturing the water-absorbent paper by the wet method, wherein the preparation of the water-absorbent resin for manufacturing the water-absorbent paper by the wet method comprises the following steps:
(1) mixing acrylic acid, water, a cross-linking agent and hydrophobic silicon dioxide, introducing nitrogen to remove oxygen, adding an initiator to initiate polymerization, and performing heat preservation treatment to obtain a polymer colloid;
(2) granulating the polymerized colloid obtained in the step (1) to obtain resin particles;
(3) neutralizing the resin particles obtained in the step (2) with an alkaline solution, spraying a first surface treatment solution for carrying out first surface treatment, and drying and crushing the first surface treatment solution in sequence to obtain water-absorbent resin particles;
(4) spraying a second surface treatment liquid on the surfaces of the water-absorbent resin particles obtained in the step (3) to perform a second surface treatment to obtain high-molecular water-absorbent resin particles;
(5) and (3) heating the macromolecular water-absorbent resin particles obtained in the step (4) to 100-160 ℃, adding a coating agent, adding hydrophilic liquid silicon dioxide, uniformly stirring, and cooling to obtain the water-absorbent resin for manufacturing the water-absorbent paper by the wet method.
Preferably, the amount of each raw material for preparing the water absorbent resin for wet-process water absorbent paper is as follows: 100-300 parts of acrylic acid, 100-300 parts of alkaline solution, 5-20 parts of cross-linking agent, 100-700 parts of water, 1-6 parts of hydrophobic silica, 0.5-2.5 parts of initiator, 20-100 parts of first surface treatment liquid, 3-25 parts of second surface treatment liquid, 5-10 parts of coating agent and 1-3 parts of hydrophilic liquid silica.
Preferably, the cross-linking agent is one or more of tetraallyloxyethane, trimethylolpropane triacrylate, N-methylene bisacrylamide and N-hydroxymethyl acrylamide; preferably, the cross-linking agent is a composite long-chain cross-linking agent formed by compounding two or three of tetraallyloxyethane, trimethylolpropane triacrylate, N-methylene diacrylamide and N-hydroxymethyl acrylamide; more preferably, the crosslinking agent is composed of trimethylolpropane triacrylate and tetraallyloxyethane, and the mass ratio of the trimethylolpropane triacrylate to the amount of tetraallyloxyethane used is 1: (0.8 to 1.4).
Preferably, the initiator is a redox initiator, the oxidizing agent in the redox initiator is one or more of hydrogen peroxide, ammonium persulfate and potassium persulfate, and the reducing agent in the redox initiator is sodium bisulfite and/or ascorbic acid; preferably, the mass ratio of the oxidant to the reducing agent is 1: (1.2-2.5).
Preferably, the first surface treatment liquid is one or more of polyols, polyamine compounds and epoxy compounds; preferably, the polyalcohol is one or more of ethylene glycol, butanediol, glycerol and triethylene glycol; the polyamine compound is one or more of ethylenediamine, diethylenediamine and triethylenediamine; the epoxy compound is one or more of butanediol diglycidyl ether, polyglycerol polyglycidyl ether and sorbitol polyglycidyl ether; more preferably, the first surface treatment liquid consists of a glycerol solution with the concentration of 60-80 wt% and polyglycerol polyglycidyl ether, and the mass ratio of the glycerol solution to the polyglycerol polyglycidyl ether is (4-6): 1; or the first surface treatment liquid consists of a glycerol solution with the concentration of 60-80 wt% and sorbitol polyglycidyl ether, and the mass ratio of the glycerol solution to the sorbitol polyglycidyl ether is (4-6) to 1; and/or the second surface treatment liquid is an aqueous solution containing aluminum sulfate and sodium sulfate, the mass of the sodium sulfate in the aqueous solution is not more than 50% of that of the aluminum sulfate, and the total mass fraction of the aluminum sulfate and the sodium sulfate in the aqueous solution is 20% -40%.
Preferably, after the initiator is added in the step (1) to initiate the polymerization reaction, the polymerization reaction is naturally heated, and after the temperature of the polymerization reaction system does not rise any more, the heat preservation treatment is carried out; wherein the peak temperature of the natural heating is 80-90 ℃, and the temperature of the heat preservation treatment is the peak temperature of the natural heating; and/or in the step (3), neutralizing the resin particles obtained in the step (2) with an alkaline solution until the pH value is 6.0-6.5; and/or the alkaline solution is one or more of a sodium hydroxide solution, a potassium hydroxide solution, a lithium hydroxide solution, a sodium carbonate solution, a potassium carbonate solution, a lithium carbonate solution, a sodium bicarbonate solution, a potassium bicarbonate solution and a lithium bicarbonate solution; and/or the concentration of the alkaline solution is 45 wt% -50 wt%.
The invention also provides the water-absorbing resin obtained by the application of the invention and used for manufacturing the water-absorbing paper by a wet method.
In addition, the invention also provides a preparation method of the water-absorbent resin for manufacturing the water-absorbent paper by the wet method, which comprises the following steps: (1) mixing acrylic acid, water, a cross-linking agent and hydrophobic silicon dioxide, introducing nitrogen to remove oxygen, adding an initiator to initiate polymerization, and performing heat preservation treatment to obtain a polymer colloid; (2) granulating the polymerized colloid obtained in the step (1) to obtain resin particles; (3) neutralizing the resin particles obtained in the step (2) with an alkaline solution, spraying a first surface treatment solution for carrying out first surface treatment, and drying and crushing the first surface treatment solution in sequence to obtain water-absorbent resin particles; (4) spraying a second surface treatment liquid on the surfaces of the water-absorbent resin particles obtained in the step (3) to perform a second surface treatment to obtain high-molecular water-absorbent resin particles; (5) and (3) heating the macromolecular water-absorbent resin particles obtained in the step (4) to 100-160 ℃, adding a coating agent, adding hydrophilic liquid silicon dioxide, uniformly stirring, and cooling to obtain the water-absorbent resin for manufacturing the water-absorbent paper by the wet method.
In addition, the invention also provides the water-absorbent resin for the wet-process water-absorbent paper, which is prepared by the preparation method of the water-absorbent resin for the wet-process water-absorbent paper.
Compared with the prior art, the invention has at least the following beneficial effects.
(1) When the water-absorbent resin for manufacturing the water-absorbent paper by the wet method is prepared, the post-treatment process of the traditional super absorbent resin (SAP) is optimized by the special coating material (coating agent) and the special surface treatment technology, so that a layer of coating for adjusting the water absorption capacity of SAP particles is added on the surface of the traditional super absorbent resin, namely, a semi-hydrophilic film with certain toughness is formed on the surface of the traditional super absorbent resin product, and thus, when the super absorbent resin product meets water, the semi-hydrophilic protective film can absorb a small amount of water, the SAP core is temporarily prevented from absorbing water, the water absorption performance of the SAP core is ensured, meanwhile, ions and impurities in paper pulp can be prevented from entering the SAP core, the SAP performance can be furthest reserved, and the SAP gel strength can be further improved; when the water-absorbent resin for manufacturing the water-absorbent paper by the wet method is applied to the production of the water-absorbent paper, the water-absorbent resin has unique performance, and can delay the initial absorption of water in the compounding process of the water-absorbent resin and paper pulp, thereby ensuring that the full mixing of the super-absorbent resin (high-molecular water-absorbent resin) and the paper pulp does not influence the absorption performance of the super-absorbent resin and the paper pulp, and being very suitable for the preparation process of the water-absorbent paper by the wet method.
(2) In the process of preparing the water-absorbent resin for manufacturing the water-absorbent paper by the wet method, when the polymer colloid is prepared, acrylic acid, water, a cross-linking agent and hydrophobic silica are mixed, wherein the hydrophobic silica is added to jointly act with a semi-hydrophilic film formed on the surface of a high-molecular water-absorbent resin particle, so that the super-absorbent resin prepared by the method has unique performance, can delay the initial absorption of water in the compounding process with paper pulp, ensures the full mixing of the super-absorbent resin and the paper pulp and does not influence the absorption performance of the super-absorbent resin and the paper pulp, and is very suitable for the preparation process of the water-absorbent paper by the wet method; the super absorbent resin prepared by the invention solves the problems that the common super absorbent resin can absorb a large amount of liquid in the mixing process with paper pulp when being applied to wet papermaking due to strong hydrophilicity, and the performance of SAP is seriously reduced after drying.
(3) According to the invention, the coating agent and the hydrophilic liquid silicon dioxide are added into the obtained high polymer water-absorbent resin particles, because the high polymer water-absorbent resin particles need to be heated to 100-160 ℃ when the coating agent is used for coating the surface of the high polymer water-absorbent resin particles, and under the condition, the coating agent is melted at high temperature, so that the high polymer water-absorbent resin particles are bonded into blocks.
(4) When the water-absorbent resin (super absorbent resin) is applied to the production of wet-process water-absorbent paper, the absorption characteristic of the super absorbent resin (SAP) can be retained to the greatest extent, the contact area of the high-molecular water-absorbent resin and paper fiber can be greatly improved, the conductivity of the paper fiber and the super absorbent resin to liquid can be obviously enhanced, the absorption capacity and the absorption speed of the water-absorbent paper to the liquid can be greatly improved, the repeated liquid absorption capacity of the water-absorbent paper can be greatly improved, and a new 'wet-process water-absorbent paper preparation method' is created by adding the super absorbent resin.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
The present invention provides in a first aspect a method for producing a water-absorbent resin for use in the wet process for producing water-absorbent paper, the method comprising the steps of: (1) mixing acrylic acid, water, a cross-linking agent and hydrophobic silicon dioxide, introducing nitrogen to remove oxygen (for example, introducing nitrogen to remove oxygen to enable the oxygen content to be within 1 ppm), adding an initiator to initiate a polymerization reaction, and performing heat preservation treatment to obtain a polymer colloid; (2) granulating the polymerized colloid obtained in the step (1) to obtain resin particles; (3) neutralizing the resin particles obtained in the step (2) with an alkaline solution, spraying a first surface treatment liquid (surface treatment liquid I) for carrying out first surface treatment, and drying and crushing the first surface treatment liquid in sequence to obtain water-absorbent resin particles; (4) spraying a second surface treatment liquid (surface treatment liquid II) on the surfaces of the water-absorbent resin particles obtained in the step (3) to perform second surface treatment to obtain high-molecular water-absorbent resin particles; (5) heating the macromolecular water-absorbent resin particles obtained in the step (4) to 100-160 ℃ (for example, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃, 150 ℃ or 160 ℃), preferably to 120 ℃, then adding a coating agent, then adding liquid silicon dioxide (hydrophilic silicon dioxide), uniformly stirring, and finally cooling to obtain the water-absorbent resin (super water-absorbent resin) for manufacturing the water-absorbent paper by the wet method; preferably, heating the macromolecular water-absorbent resin particles obtained in the step (4) to 100-160 ℃, then adding a coating agent and uniformly stirring, then adding liquid silicon dioxide and uniformly stirring, and finally cooling to obtain the super absorbent resin for manufacturing the absorbent paper by the wet method; in the present invention, the coating agent may be, for example, an amphiphilic oligomer.
According to the method, a post-treatment process of the traditional super absorbent resin (SAP) is optimized through a special coating material (amphiphilic oligomer) and a special surface treatment technology, so that a layer of coating for adjusting the water absorption capacity of SAP particles is added on the surface of the traditional super absorbent resin, namely, a semi-hydrophilic film with certain toughness is formed on the surface of the traditional super absorbent resin product, and thus, when the super absorbent resin product meets water, the semi-hydrophilic protective film can absorb a small amount of water and temporarily prevent SAP cores from absorbing water, so that the water absorption performance of SAP cores is ensured, and meanwhile, ions and impurities in paper pulp can be prevented from entering the SAP cores, and the SAP performance can be retained to the maximum extent; according to the invention, the coating agent is added to carry out special surface treatment on the high-molecular water-absorbent resin particles, so that the SAP gel strength can be further improved.
In the invention, the hydrophobic silicon dioxide and the semi-hydrophilic film formed on the surface of the high molecular water-absorbent resin particles act together, so that the super absorbent resin prepared by the invention has unique performance, and can delay the absorption of water in the initial stage in the compounding process of the super absorbent resin and paper pulp, thereby ensuring that the full mixing of the super absorbent resin and the paper pulp does not influence the absorption performance of the super absorbent resin and the paper pulp, and being very suitable for the preparation process of wet absorbent paper; the super absorbent resin prepared by the invention solves the problems that the common super absorbent resin can absorb a large amount of liquid in the mixing process with paper pulp when being applied to wet papermaking due to strong hydrophilicity, and the performance of SAP is seriously reduced after drying; in the invention, the hydrophilic liquid silicon dioxide is added to effectively prevent the high molecular water-absorbent resin particles from being bonded after the coating treatment, so that the water-absorbent resin for manufacturing the water-absorbent paper by a wet method can be uniformly dispersed.
According to some preferred embodiments, the amount of each raw material for preparing the water absorbent resin for wet-process water absorbent paper is as follows: 100 to 300 parts by weight (e.g., 100, 150, 200, 250 or 300 parts by weight) of acrylic acid, 100 to 300 parts by weight (e.g., 100, 104, 150, 196, 200, 222, 250 or 300 parts by weight) of an alkaline solution, 5 to 20 parts by weight (e.g., 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5, 16, 16.5, 17, 17.5, 18, 18.5, 19, 19.5 or 20 parts by weight) of a crosslinking agent, 100 to 700 parts by weight (e.g., 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650 or 700 parts by weight) of water, 1 to 6 parts by weight (e.g., 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, or 0.5 parts by weight (e.5 parts by weight) of a first treating agent, 0.5 to 5 parts by weight (e.5 parts by weight) of a surface treating agent, 0.5 to 5 parts (e.5 parts by weight) of a second, 25. 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 or 100 parts by weight), 3 to 25 parts by weight (for example, 3, 5, 5.5, 8, 10, 12, 15, 18, 20, 22 or 25 parts by weight) of the second surface treatment liquid, 5 to 10 parts by weight (for example, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5 or 10 parts by weight) of the coating agent, and 1 to 3 parts by weight (for example, 1, 1.5, 2, 2.5 or 3 parts by weight) of the liquid silica.
According to some preferred embodiments, the coating agent is prepared by the following steps: (a) mixing 5 to 30 parts by weight (e.g., 5, 10, 15, 20, 25 or 30 parts by weight) of acrylic acid with 10 to 80 parts by weight (e.g., 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75 or 80 parts by weight) of ethylene under a pressure of 2 to 5MPa (e.g., 2, 2.5, 3, 3.5, 4, 4.5 or 5MPa) and adding 0.2 to 1 part by weight (e.g., 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1 part by weight) of azobisisobutyronitrile to obtain a reaction solution; (b) and (b) reacting the reaction solution obtained in the step (a) for 1-3 h (for example, 1, 1.5, 2, 2.5 or 3h) under the conditions that the pressure is 2-5 MPa (for example, 2, 2.5, 3, 3.5, 4, 4.5 or 5MPa) and the temperature is 40-80 ℃ (for example, 40 ℃, 45 ℃, 50 ℃, 55 ℃, 60 ℃, 65 ℃, 70 ℃, 75 ℃ or 80 ℃) to obtain the film coating agent.
In the present invention, preferably, the coating agent is the amphiphilic oligomer coating agent self-prepared in the steps (a) and (b) of the present invention, and the inventors found that the self-prepared coating agent of the present invention is more beneficial to forming a semi-hydrophilic film with certain toughness on the surface of the polymer water-absorbent resin particles, so as to better adjust the water absorption capacity of the SAP particles and maximally retain the absorption performance of the SAP.
According to some specific embodiments, the self-made coating agent is prepared by the following steps: putting 5-30 parts by weight of acrylic acid and 10-80 parts by weight of ethylene into a reaction kettle under the pressurizing condition of the pressure of 3-5 MPa, adding 0.2-1 part by weight of azobisisobutyronitrile, reacting for 2 hours under the condition that the pressure is 3-5 MPa and the temperature is heated to 50 ℃ to obtain the coating agent, and preserving the heat at 80 ℃ for later use.
According to some preferred embodiments, the cross-linking agent is one or more of tetraallyloxyethane, trimethylolpropane triacrylate, N-methylenebisacrylamide, N-methylolacrylamide; preferably, the cross-linking agent is a composite long-chain cross-linking agent formed by compounding two or three of tetraallyloxyethane, trimethylolpropane triacrylate, N-methylene diacrylamide and N-hydroxymethyl acrylamide; more preferably, the crosslinking agent is composed of trimethylolpropane triacrylate and tetraallyloxyethane, and the mass ratio of the trimethylolpropane triacrylate to the amount of tetraallyloxyethane used is 1: (0.8 to 1.4); in the present invention, for example, it is preferable to use a complex long-chain crosslinking agent to make the molecular chain of the produced super absorbent resin more spread and the internal network more uniform.
According to some preferred embodiments, the initiator is a redox initiator, the oxidizing agent in the redox initiator is one or more of hydrogen peroxide, ammonium persulfate and potassium persulfate, and the reducing agent in the redox initiator is sodium bisulfite and/or ascorbic acid. When the initiator is a redox initiator, the amount of the initiator is the sum of the amounts of the oxidizing agent and the reducing agent, and preferably the mass ratio of the amount of the oxidizing agent to the amount of the reducing agent is 1: (1.2-2.5).
According to some preferred embodiments, the first surface treatment liquid (first surface cross-linking liquid) is one or more of a polyol, a polyamine compound, and an epoxy compound; and/or the second surface treatment liquid (second surface cross-linking liquid) is an aqueous solution containing aluminum sulfate and sodium sulfate, the sodium sulfate in the aqueous solution is not more than 50% by mass of the aluminum sulfate, and the total mass fraction of the aluminum sulfate and the sodium sulfate contained in the aqueous solution is 20% to 40% (e.g., 20%, 25%, 30%, 35%, or 40%). In the present invention, an aqueous solution containing aluminum sulfate and sodium sulfate is also referred to as an aluminum sulfate sodium sulfate solution.
According to some preferred embodiments, the polyhydric alcohol is one or more of ethylene glycol, butylene glycol, glycerol, triethylene glycol; and/or the polyamine compound is one or more of ethylenediamine, diethylenediamine and triethylenediamine; and/or the epoxy compound is one or more of butanediol diglycidyl ether, polyglycerol polyglycidyl ether and sorbitol polyglycidyl ether.
According to some more preferred embodiments, the first surface treatment liquid is composed of a glycerol solution having a concentration of 60 to 80 wt% (e.g., 60 wt%, 65 wt%, 70 wt%, 75 wt%, or 80 wt%), preferably 70 wt%, and a polyglycerol polyglycidyl ether, and the mass ratio of the glycerol solution to the polyglycerol polyglycidyl ether is (4 to 6): 1.
According to some more preferred embodiments, the first surface treatment liquid is composed of a glycerol solution having a concentration of 60 to 80 wt% (e.g., 60 wt%, 65 wt%, 70 wt%, 75 wt%, or 80 wt%), preferably 70 wt%, and sorbitol polyglycidyl ether, and the mass ratio of the glycerol solution to the sorbitol polyglycidyl ether is (4 to 6): 1.
According to some preferred embodiments, after the nitrogen is introduced to remove oxygen in the step (1), the initiator is added at the temperature of 3-5 ℃.
According to some preferred embodiments, after the initiator is added in the step (1) to initiate the polymerization reaction, the polymerization reaction is naturally heated, and after the temperature of the polymerization reaction system does not rise any more, the heat preservation treatment is carried out; wherein the peak temperature of the natural temperature rise is 80 to 90 ℃ (e.g., 80 ℃, 81 ℃, 82 ℃, 83 ℃, 84 ℃, 85 ℃, 86 ℃, 87 ℃, 88 ℃, 89 ℃ or 90 ℃), and the temperature of the heat preservation treatment is the peak temperature of the natural temperature rise; in the present invention, the temperature of the heat-preserving treatment may be, for example, 3 to 6 hours (e.g., 3, 3.5, 4, 4.5, 5, 5.5, or 6 hours), and preferably 4 hours.
According to some preferred embodiments, in step (3), the resin particles obtained in step (2) are neutralized with an alkaline solution to a pH of 6.0 to 6.5 (e.g., 6.0, 6.1, 6.2, 6.3, 6.4, or 6.5); and/or the alkaline solution is one or more of a sodium hydroxide solution, a potassium hydroxide solution, a lithium hydroxide solution, a sodium carbonate solution, a potassium carbonate solution, a lithium carbonate solution, a sodium bicarbonate solution, a potassium bicarbonate solution and a lithium bicarbonate solution; and/or the concentration of the alkaline solution is 45 wt% to 50 wt% (e.g., 45 wt%, 46 wt%, 47 wt%, 48 wt%, 49 wt%, or 50 wt%); in the present invention, the alkaline solution may preferably be, for example, a sodium hydroxide solution having a concentration of 48 wt% (mass concentration).
According to some preferred embodiments, the temperature of the drying in the step (3) is 110 to 130 ℃.
According to some specific embodiments, the raw materials required for preparing the water-absorbent resin (super absorbent resin) for wet papermaking according to the present invention are: 100-300 parts of acrylic acid, 100-300 parts of a 48 wt% sodium hydroxide solution, 5-20 parts of a cross-linking agent, 100-700 parts of water, 1-6 parts of hydrophobic silica, 0.5-2.5 parts of an initiator, 20-100 parts of a surface treatment liquid, 3-25 parts of a surface treatment liquid, 5-10 parts of a coating agent and 1-3 parts of liquid silica; the preparation process is as follows.
Firstly, mixing acrylic acid, water, a cross-linking agent and hydrophobic silicon dioxide, introducing nitrogen to remove oxygen, adjusting the temperature to 3-5 ℃, adding an initiator to initiate polymerization reaction, and naturally heating the polymerization reaction; the cross-linking agent is preferably the compound of two or three of tetraallyloxyethane, trimethylolpropane triacrylate, N-methylene diacrylamide and N-hydroxymethyl acrylamide.
And secondly, regarding the temperature of the polymerization reaction as the reaction is finished when the temperature of the polymerization reaction does not rise any more, preserving the heat at the temperature of 80-90 ℃ after the reaction is finished to obtain a polymer colloid, and granulating the polymer colloid to obtain the resin particles.
Neutralizing the resin particles with a sodium hydroxide solution until the pH value is 6.0-6.5, spraying a first surface treatment solution to perform surface treatment, and drying and crushing the first surface treatment solution in sequence to obtain the water-absorbent resin particles.
And fourthly, spraying surface treatment liquid onto the surfaces of the water-absorbent resin particles to obtain the high-molecular water-absorbent resin particles.
Fifthly, heating the high molecular water-absorbent resin particles to 120 ℃, adding the coating agent, uniformly stirring at a high speed, then adding the liquid silicon dioxide, continuously uniformly stirring, and finally cooling to normal temperature to obtain the water-absorbent resin for manufacturing the water-absorbent paper by the wet method.
According to the invention, a semi-hydrophilic film with certain toughness is formed on the surface of the product through a special surface treatment method (a surface treatment method of adding a coating agent for coating), when the product meets water, the protective film can absorb a small amount of water and temporarily prevent the inner core from absorbing water, so that the water absorption performance of the SAP inner core is ensured, the common super absorbent resin has strong hydrophilicity, so that a large amount of liquid can be absorbed in the mixing process of the common super absorbent resin and paper pulp when the common super absorbent resin is applied to wet papermaking, and the performance of the SAP is seriously reduced after drying; when the super absorbent resin prepared by the method is applied to the production of absorbent paper, the super absorbent resin has unique performance, can be fully mixed with paper pulp without influencing the absorption performance of the super absorbent resin, and is very suitable for the preparation process of wet absorbent paper; the invention optimizes the traditional SAP post-treatment process to further improve the SAP gel strength, and adds a layer of coating for adjusting the water absorption capacity of SAP particles by special coating materials (amphiphilic oligomers) and technology, wherein the coating has certain toughness, can absorb a small amount of water, can prevent ions and impurities in paper pulp from entering SAP cores, and can furthest maintain the SAP performance.
The present invention provides, in a second aspect, a water-absorbent resin (super absorbent resin) for use in the wet process for producing water-absorbent paper, which is produced by the production method according to the first aspect of the present invention. The super absorbent resin provided by the invention is a novel super absorbent resin special for manufacturing absorbent paper by a wet method, when the super absorbent resin is applied to the production of the wet method absorbent paper, the absorption characteristic of the super absorbent resin (SAP) can be retained to the greatest extent, the contact area of the high polymer water absorbent resin and paper fibers can be greatly increased, the conductivity of the paper fibers and the super absorbent resin to liquid is obviously enhanced, so that the absorption capacity and the absorption speed of the absorbent paper to the liquid are greatly increased, the repeated liquid absorption capacity of the absorbent paper can be greatly increased, and a novel method for manufacturing the absorbent paper by the wet method is created by adding the super absorbent resin.
The invention also provides a method for manufacturing the absorbent paper by a wet method, which comprises the following steps: s1, respectively forming the surface sizing agent and the bottom sizing agent through netting to obtain wet surface paper and wet bottom paper; s2 spraying the wet top sheet and the wet bottom sheet obtained in step S1 with the super absorbent resin for wet manufacturing of absorbent paper according to the first aspect of the present invention, respectively, and combining the wet top sheet and the wet bottom sheet, to which the super absorbent resin is sprayed, respectively, to obtain wet paper sheets; and S3, pressing and drying the wet paper sheet prepared in the step S2 in sequence to prepare the absorbent paper.
In particular, the method for manufacturing absorbent paper by wet process provided by the present invention can adopt other technologies, for example, the related technology in chinese patent application CN201710966882.0, except that the super absorbent resin used in the method for manufacturing absorbent paper by wet process according to the first aspect of the present invention is the super absorbent resin used in the method for manufacturing absorbent paper by wet process.
According to some preferred embodiments, the method further comprises, before step S1, pulping and refining the raw materials of the surface slurry and the bottom slurry, respectively, and then preparing the pulp to obtain the surface slurry and the bottom slurry, respectively; preferably, the concentration of the crushed pulp is 4 wt% to 6 wt%; the pulping time is 10-20 min; the grinding power of the grinding is 280-360 kW; the passing amount of the pulp in the pulp grinding process is 1800-2100L/min; the concentration of the ground pulp is 3.8-4.2 wt%; adding an additive in the pulp mixing process, wherein the additive consists of a wet strength agent and/or a softening agent; and/or the method further comprises the step of winding, cutting and packaging the absorbent paper prepared in the step S3 in sequence.
According to some preferred embodiments, the feedstock of the top and/or bottom pulp consists of wood and/or straw pulp; the wood pulp consists of softwood pulp and/or hardwood pulp; preferably, the raw materials of the surface sizing agent and/or the bottom sizing agent consist of softwood pulp and hardwood pulp, and the weight ratio of the softwood pulp to the hardwood pulp is (20-40): (60-80).
According to some preferred embodiments, the concentration of the upper wire in step S1 is 0.6 wt% to 0.8 wt%; the relative water content of the wet surface layer paper and/or the wet bottom layer paper prepared in the step S1 is 50-80%; the dry wet face layer paper prepared in the step S1 has a gram weight of 20-50 g/m2The dry basis weight of the wet bottom layer paper is 20-60 g/m2(ii) a In the step S2, the spraying (spraying) amount of the super absorbent resin on the wet surface layer paper and/or the wet bottom layer paper is 35-60 g/m2(ii) a The relative water content of the absorbent paper prepared in the step S3 is 6-8%.
Example 1: the raw materials for preparing the super absorbent resin for wet papermaking comprise: 100 parts by weight of acrylic acid, 700 parts by weight of deionized water, 2 parts by weight of hydrophobic silica, 3 parts by weight of trimethylolpropane triacrylate, 2.5 parts by weight of tetraallyloxyethane, 0.4 parts by weight of potassium persulfate, 0.6 parts by weight of sodium bisulfite, 104 parts by weight of 48% by weight of sodium hydroxide solution, 29 parts by weight of 70% by weight of glycerol solution, 5 parts by weight of polyglycerol polyglycidyl ether, 40% by weight (total mass fraction of aluminum sulfate and sodium sulfate) of aluminum sulfate sodium sulfate solution 5.5 parts by weight (aluminum sulfate: sodium sulfate: 2:1), 5 parts by weight of a film coating agent and 1.2 parts by weight; the coating agent is an amphiphilic oligomer coating agent prepared by the invention, and the preparation process comprises the following steps: putting 10 parts by weight of acrylic acid and 20 parts by weight of ethylene into a reaction kettle under the pressurizing condition of the pressure of 3MPa, adding 0.5 part by weight of azobisisobutyronitrile, reacting for 2 hours under the condition of the pressure of 3MPa and the temperature of heating to 50 ℃ to obtain a coating agent, and preserving heat at 80 ℃ for later use.
The specific preparation process of the super absorbent resin for wet papermaking comprises the following steps: mixing acrylic acid, deionized water, trimethylolpropane triacrylate, tetraallyloxyethane and hydrophobic silicon dioxide, introducing nitrogen to remove oxygen, adding potassium persulfate and sodium bisulfite to initiate polymerization reaction at 5 ℃, and naturally heating the polymerization reaction; secondly, the temperature of the polymerization reaction is not increased any more, namely the reaction is finished, the temperature peak is 85 ℃, the temperature is kept for 4 hours, the polymerization colloid is obtained, and the resin particles are obtained by granulating the polymerization colloid; thirdly, neutralizing the resin particles with 48 wt% of sodium hydroxide solution until the pH value is 6.0, then spraying a mixed solution of glycerol and polyglycerol polyglycidyl ether for surface treatment, and drying and crushing the mixture in sequence to obtain water-absorbent resin particles; fourthly, spraying an aluminum sulfate sodium sulfate solution on the surfaces of the water-absorbent resin particles to obtain high-molecular water-absorbent resin particles; fifthly, heating the high polymer water-absorbent resin particles to 120 ℃, adding the coating agent, stirring uniformly at a high speed, then adding the liquid silicon dioxide, continuously stirring uniformly, and finally cooling to normal temperature to obtain the super absorbent resin.
Example 2: the raw materials for preparing the super absorbent resin for wet papermaking comprise: 200 parts by weight of acrylic acid, 600 parts by weight of deionized water, 4 parts by weight of hydrophobic silica, 5.5 parts by weight of trimethylolpropane triacrylate, 0.7 part by weight of potassium persulfate, 1.3 parts by weight of ascorbic acid, 48 parts by weight of sodium hydroxide solution 196, 70 parts by weight of glycerol solution 48, 10 parts by weight of polyglycerol polyglycidyl ether, 30 parts by weight (total mass fraction of aluminum sulfate and sodium sulfate) of aluminum sulfate sodium sulfate solution 15 (aluminum sulfate: sodium sulfate 3:1), 7.5 parts by weight of a film coating agent and 1.5 parts by weight of liquid silica; the coating agent is an amphiphilic oligomer coating agent prepared by the invention, and the preparation process comprises the following steps: putting 15 parts by weight of acrylic acid and 15 parts by weight of ethylene into a reaction kettle under the pressurizing condition of the pressure of 3MPa, adding 0.3 part by weight of azobisisobutyronitrile, reacting for 2 hours under the condition of the pressure of 3MPa and the temperature of 60 ℃ to obtain a coating agent, and preserving heat at 80 ℃ for later use.
The specific preparation process of the super absorbent resin for wet papermaking comprises the following steps: mixing acrylic acid, deionized water, trimethylolpropane triacrylate and hydrophobic silicon dioxide, introducing nitrogen to remove oxygen, adding potassium persulfate and ascorbic acid to initiate polymerization reaction at 3 ℃, and naturally heating the polymerization reaction; secondly, the temperature of the polymerization reaction is not increased any more, namely the reaction is finished, the temperature peak is 86 ℃, the temperature is kept for 4 hours, the polymerization colloid is obtained, and the resin particles are obtained by granulating the polymerization colloid; thirdly, neutralizing the resin particles with 48 wt% of sodium hydroxide solution until the pH value is 6.2, then spraying a mixed solution of glycerol and polyglycerol polyglycidyl ether for surface treatment, and drying and crushing the mixture in sequence to obtain water-absorbent resin particles; fourthly, spraying an aluminum sulfate sodium sulfate solution on the surfaces of the water-absorbent resin particles to obtain high-molecular water-absorbent resin particles; fifthly, heating the high polymer water-absorbent resin particles to 120 ℃, adding the coating agent, stirring uniformly at a high speed, then adding the liquid silicon dioxide, continuously stirring uniformly, and finally cooling to normal temperature to obtain the super absorbent resin.
Example 3: the raw materials for preparing the super absorbent resin for wet papermaking comprise: 250 parts of acrylic acid, 600 parts of deionized water, 5 parts of hydrophobic silica, 5.5 parts of tetraallyloxyethane, 0.6 part of potassium persulfate, 1.3 parts of ascorbic acid, 222 parts of 48 wt% of sodium hydroxide solution, 57 parts of 70 wt% of glycerol solution, 13 parts of sorbitol polyglycidyl ether, 20 wt% (total mass fraction of aluminum sulfate and sodium sulfate) of aluminum sulfate sodium sulfate solution 18 (aluminum sulfate: sodium sulfate ═ 7:3), 10 parts of coating agent and 1.8 parts of liquid silica; the coating agent is an amphiphilic oligomer coating agent prepared by the invention, and the preparation process comprises the following steps: adding 30 parts by weight of acrylic acid and 10 parts by weight of ethylene into a reaction kettle under the pressurizing condition of the pressure of 3MPa, adding 1 part by weight of azobisisobutyronitrile, reacting for 2 hours under the temperature condition of the pressure of 3MPa and heating to 70 ℃ to obtain a coating agent, and preserving heat at 80 ℃ for later use.
The specific preparation process of the super absorbent resin for wet papermaking comprises the following steps: mixing acrylic acid, deionized water, tetraallyloxyethane and hydrophobic silicon dioxide, introducing nitrogen to remove oxygen, adding potassium persulfate and ascorbic acid to initiate polymerization reaction at 5 ℃, and naturally heating the polymerization reaction; secondly, the temperature of the polymerization reaction is not increased any more, namely the reaction is finished, the temperature peak is 83 ℃, the temperature is kept for 4 hours, the polymerization colloid is obtained, and the resin particles are obtained by granulating the polymerization colloid; thirdly, neutralizing the resin particles with 48 wt% of sodium hydroxide solution until the pH value is 6.5, then spraying a mixed solution of glycerol and sorbitol polyglycidyl ether for surface treatment, and drying and crushing the mixture in sequence to obtain water-absorbent resin particles; fourthly, spraying an aluminum sulfate sodium sulfate solution on the surfaces of the water-absorbent resin particles to obtain high-molecular water-absorbent resin particles; fifthly, heating the high polymer water-absorbent resin particles to 120 ℃, adding the coating agent, stirring uniformly at a high speed, then adding the liquid silicon dioxide, continuously stirring uniformly, and finally cooling to normal temperature to obtain the super absorbent resin.
Example 4: the raw materials for preparing the super absorbent resin for wet papermaking comprise: 300 parts by weight of acrylic acid, 500 parts by weight of deionized water, 6 parts by weight of hydrophobic silica, 4.5 parts by weight of trihydroxypropane triacrylate, 6 parts by weight of tetraallyloxyethane, 0.7 parts by weight of potassium persulfate, 1.6 parts by weight of sodium bisulfite, 250 parts by weight of 48% by weight of sodium hydroxide solution, 79 parts by weight of 70% by weight of glycerol solution, 15 parts by weight of sorbitol polyglycidyl ether, 25% by weight (total mass fraction of aluminum sulfate and sodium sulfate) of aluminum sulfate sodium sulfate solution 22 (aluminum sulfate: sodium sulfate: 5:2), 8 parts by weight of a coating agent and 2.5 parts by weight of liquid silica; the coating agent is an amphiphilic oligomer coating agent prepared by the invention, and the preparation process comprises the following steps: putting 25 parts by weight of acrylic acid and 35 parts by weight of ethylene into a reaction kettle under the pressurizing condition of the pressure of 3MPa, adding 0.5 part by weight of azobisisobutyronitrile, reacting for 2 hours under the condition of the pressure of 3MPa and the temperature of 60 ℃ to obtain a coating agent, and preserving heat at 80 ℃ for later use.
The specific preparation process of the super absorbent resin for wet papermaking comprises the following steps: mixing acrylic acid, deionized water, trimethylolpropane triacrylate, tetraallyloxyethane and hydrophobic silicon dioxide, introducing nitrogen to remove oxygen, adding potassium persulfate and sodium bisulfite to initiate polymerization reaction at 5 ℃, and naturally heating the polymerization reaction; secondly, the temperature of the polymerization reaction is not increased any more, namely the reaction is finished, the temperature peak is 87 ℃, the temperature is kept for 4 hours, the polymerization colloid is obtained, and the resin particles are obtained by granulating the polymerization colloid; thirdly, neutralizing the resin particles with 48 wt% of sodium hydroxide solution until the pH value is 6.0, then spraying a mixed solution of glycerol and sorbitol polyglycidyl ether for surface treatment, and drying and crushing the mixture in sequence to obtain water-absorbent resin particles; fourthly, spraying an aluminum sulfate sodium sulfate solution on the surfaces of the water-absorbent resin particles to obtain high-molecular water-absorbent resin particles; fifthly, heating the high polymer water-absorbent resin particles to 120 ℃, adding the coating agent, stirring uniformly at a high speed, then adding the liquid silicon dioxide, continuously stirring uniformly, and finally cooling to normal temperature to obtain the super absorbent resin.
Comparative example 1: the preparation method of the high-molecular water-absorbent resin comprises the following steps: the paint comprises, by weight, 200 parts of acrylic acid, 600 parts of deionized water, 12 parts of N, N-methylene bisacrylamide, 0.3 part of potassium persulfate, 0.7 part of ascorbic acid, 200 parts of 48 wt% sodium hydroxide solution, 30 parts of ethanol, 10 parts of glycerol, 4 parts of 50 wt% butanediol diglycidyl ether solution and 3 parts of liquid silicon dioxide.
The preparation process comprises the following steps: mixing acrylic acid, deionized water and N, N-methylene diacrylamide, introducing nitrogen to remove oxygen, adding potassium persulfate and ascorbic acid to initiate polymerization reaction at 5 ℃, and naturally heating the polymerization reaction; secondly, the temperature of the polymerization reaction is not increased any more, namely the reaction is finished, after the reaction is finished, the temperature is kept at 85 ℃ to obtain polymerized colloid, and the polymerized colloid is granulated to obtain resin particles; thirdly, neutralizing the resin particles with 48 wt% of sodium hydroxide solution until the pH value is 6.3, then spraying 50 wt% of butanediol diglycidyl ether solution for surface treatment, and drying and crushing the solution in sequence to obtain water-absorbent resin particles; mixing and stirring the obtained water-absorbent resin particles with ethanol and glycerol uniformly, adding liquid silicon dioxide, continuously stirring uniformly, and finally drying at 120 ℃ to obtain the high-molecular water-absorbent resin.
Comparative example 2: the preparation method of the high-molecular water-absorbent resin comprises the following steps: the liquid silicon dioxide cleaning agent comprises, by weight, 100 parts of acrylic acid, 700 parts of deionized water, 7 parts of N-hydroxymethyl acrylamide, 0.2 part of potassium persulfate, 0.6 part of sodium bisulfite, 100 parts of 48 wt% sodium hydroxide solution, 20 parts of ethanol, 8 parts of glycerol, 2 parts of 50 wt% butanediol diglycidyl ether solution and 1.2 parts of liquid silicon dioxide.
The preparation process comprises the following steps: mixing acrylic acid, deionized water and N-hydroxymethyl acrylamide, introducing nitrogen to remove oxygen, adding potassium persulfate and ascorbic acid to initiate polymerization reaction at 5 ℃, and naturally heating the polymerization reaction; secondly, the temperature of the polymerization reaction is not increased any more, namely the reaction is finished, after the reaction is finished, the temperature is kept at 86 ℃ to obtain polymerized colloid, and the polymerized colloid is granulated to obtain resin particles; thirdly, neutralizing the resin particles with 48 wt% of sodium hydroxide solution until the pH value is 6.2, then spraying 50 wt% of butanediol diglycidyl ether solution for surface treatment, and then drying and crushing the solution in sequence to obtain water-absorbent resin particles; mixing and stirring the obtained water-absorbent resin particles with ethanol and glycerol uniformly, adding liquid silicon dioxide, continuously stirring uniformly, and finally drying at 120 ℃ to obtain the high-molecular water-absorbent resin.
In the present invention, the water retention and liquid permeability of the super absorbent resins (before wet processing) obtained in examples 1 to 4 and comparative examples 1 to 2 were measured under the conditions specified in GB/T22905-2008, and the results are shown in Table 1. In the present invention, absorbent cores comprising the super absorbent resins of examples 1 to 4 and comparative examples 1 to 2 were produced by the related wet processing technique referred to in CN201710966882.0, wherein the water retention of the super absorbent resin after wet processing was measured by the following method: the water retention rate R1 of the absorbent core containing superabsorbent resin obtained by wet processing and the water retention rate R2 of the absorbent core containing no superabsorbent resin of the same area were measured, and the water retention rate of the superabsorbent resin after wet processing was determined by subtracting R2 from R1, and the results are shown in table 1; the method for testing the liquid passing capacity of the super absorbent resin processed by the wet method comprises the following steps: the absorbent core containing the super absorbent resin obtained by wet processing is cut into a circle and placed in a holder, a water inlet pipe is arranged in the middle of the upper layer of the holder, water outlets are arranged at the periphery of the lower layer of the holder, and under the condition that the pressure is 0.3Psi, the water yield within a specific time is measured to represent the liquid passing performance (liquid passing capacity) of the super absorbent resin after wet processing, and the results are shown in table 1.
Table 1: the indices of the super absorbent resin prepared in the examples and comparative examples are as follows.
As can be seen from the data in Table 1, the super absorbent resins prepared by examples 1 to 4 of the present invention have greatly improved index compared to the super absorbent resin prepared by comparative example, and the super absorbent resin prepared by the present invention maintains the absorption characteristics of SAP to the maximum extent when applied to the production of wet absorbent paper.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. The preparation method of the film coating agent is characterized by comprising the following steps:
(a) mixing 5-30 parts by weight of acrylic acid and 10-80 parts by weight of ethylene under the pressure of 2-5 MPa, and adding 0.2-1 part by weight of azobisisobutyronitrile to obtain a reaction solution;
(b) and (b) reacting the reaction solution obtained in the step (a) for 1-3 hours under the conditions that the pressure is 2-5 MPa and the temperature is 40-80 ℃ to obtain the coating agent.
2. The method of claim 1, wherein:
in the step (b), the reaction solution obtained in the step (a) reacts for 2 hours under the conditions that the pressure is 3-5 MPa and the temperature is 50 ℃ to obtain the film coating agent.
3. A coating agent obtained by the production method according to claim 1 or 2.
4. Use of the coating agent obtained by the production method according to claim 1 or 2 for producing a water-absorbent resin for wet-process production of water-absorbent paper, wherein the production of the water-absorbent resin for wet-process production of water-absorbent paper comprises the steps of:
(1) mixing acrylic acid, water, a cross-linking agent and hydrophobic silicon dioxide, introducing nitrogen to remove oxygen, adding an initiator to initiate polymerization, and performing heat preservation treatment to obtain a polymer colloid;
(2) granulating the polymerized colloid obtained in the step (1) to obtain resin particles;
(3) neutralizing the resin particles obtained in the step (2) with an alkaline solution, spraying a first surface treatment solution for carrying out first surface treatment, and drying and crushing the first surface treatment solution in sequence to obtain water-absorbent resin particles;
(4) spraying a second surface treatment liquid on the surfaces of the water-absorbent resin particles obtained in the step (3) to perform a second surface treatment to obtain high-molecular water-absorbent resin particles;
(5) and (3) heating the macromolecular water-absorbent resin particles obtained in the step (4) to 100-160 ℃, adding a coating agent, adding hydrophilic liquid silicon dioxide, uniformly stirring, and cooling to obtain the water-absorbent resin for manufacturing the water-absorbent paper by the wet method.
5. The use according to claim 4, wherein the water-absorbent resin for wet-process water-absorbent paper production is prepared from the following raw materials in the following amounts:
100-300 parts of acrylic acid, 100-300 parts of alkaline solution, 5-20 parts of cross-linking agent, 100-700 parts of water, 1-6 parts of hydrophobic silica, 0.5-2.5 parts of initiator, 20-100 parts of first surface treatment liquid, 3-25 parts of second surface treatment liquid, 5-10 parts of coating agent and 1-3 parts of hydrophilic liquid silica.
6. Use according to claim 4, characterized in that:
the cross-linking agent is one or more of tetraallyloxyethane, trimethylolpropane triacrylate, N-methylene diacrylamide and N-hydroxymethyl acrylamide;
preferably, the cross-linking agent is a composite long-chain cross-linking agent formed by compounding two or three of tetraallyloxyethane, trimethylolpropane triacrylate, N-methylene diacrylamide and N-hydroxymethyl acrylamide;
more preferably, the crosslinking agent is composed of trimethylolpropane triacrylate and tetraallyloxyethane, and the mass ratio of the trimethylolpropane triacrylate to the amount of tetraallyloxyethane used is 1: (0.8 to 1.4).
7. Use according to claim 4, characterized in that:
the initiator is a redox initiator, an oxidant in the redox initiator is one or more of hydrogen peroxide, ammonium persulfate and potassium persulfate, and a reducing agent in the redox initiator is sodium bisulfite and/or ascorbic acid;
preferably, the mass ratio of the oxidant to the reducing agent is 1: (1.2-2.5).
8. Use according to claim 4, characterized in that:
the first surface treatment liquid is one or more of polyalcohol, polyamine compound and epoxy compound;
preferably, the polyalcohol is one or more of ethylene glycol, butanediol, glycerol and triethylene glycol; the polyamine compound is one or more of ethylenediamine, diethylenediamine and triethylenediamine; the epoxy compound is one or more of butanediol diglycidyl ether, polyglycerol polyglycidyl ether and sorbitol polyglycidyl ether;
more preferably, the first surface treatment liquid consists of a glycerol solution with the concentration of 60-80 wt% and polyglycerol polyglycidyl ether, and the mass ratio of the glycerol solution to the polyglycerol polyglycidyl ether is (4-6): 1; or the first surface treatment liquid consists of a glycerol solution with the concentration of 60-80 wt% and sorbitol polyglycidyl ether, and the mass ratio of the glycerol solution to the sorbitol polyglycidyl ether is (4-6) to 1; and/or
The second surface treatment liquid is an aqueous solution containing aluminum sulfate and sodium sulfate, the mass of sodium sulfate in the aqueous solution is not more than 50% of that of aluminum sulfate, and the total mass fraction of aluminum sulfate and sodium sulfate in the aqueous solution is 20% -40%.
9. Use according to claim 4, characterized in that:
adding an initiator in the step (1) to initiate polymerization reaction, naturally heating the polymerization reaction, and performing heat preservation treatment after the temperature of a polymerization reaction system does not rise any more; wherein the peak temperature of the natural heating is 80-90 ℃, and the temperature of the heat preservation treatment is the peak temperature of the natural heating; and/or
In the step (3), neutralizing the resin particles obtained in the step (2) with an alkaline solution until the pH value is 6.0-6.5; and/or
The alkaline solution is one or more of a sodium hydroxide solution, a potassium hydroxide solution, a lithium hydroxide solution, a sodium carbonate solution, a potassium carbonate solution, a lithium carbonate solution, a sodium bicarbonate solution, a potassium bicarbonate solution and a lithium bicarbonate solution; and/or
The concentration of the alkaline solution is 45 wt% -50 wt%.
10. Water-absorbent resin for wet-process manufacture of water-absorbent paper, obtained by the use according to any one of claims 4 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011353220.4A CN112409521B (en) | 2019-11-20 | 2019-11-20 | Film coating agent and preparation method and application thereof |
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| CN111793226B (en) * | 2020-07-28 | 2022-05-06 | 山东诺尔生物科技有限公司 | Antistatic super absorbent resin and preparation method and application thereof |
| CN112266435B (en) * | 2020-11-03 | 2022-08-26 | 山东诺尔生物科技有限公司 | Super-absorbent resin with super-strong conductivity and preparation method and application thereof |
| CN115363860A (en) * | 2022-07-11 | 2022-11-22 | 广州华一生物科技有限公司 | High-water-absorption negative-pressure wound protection device |
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| CN112522995A (en) | 2021-03-19 |
| CN112341642A (en) | 2021-02-09 |
| CN110628051B (en) | 2020-10-30 |
| CN110628051A (en) | 2019-12-31 |
| CN112409521B (en) | 2022-06-17 |
| CN112341642B (en) | 2022-03-25 |
| CN112522995B (en) | 2022-04-12 |
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