CN111039884A - Preparation method of liquid fluorescent whitening agent with stable quality for papermaking - Google Patents

Preparation method of liquid fluorescent whitening agent with stable quality for papermaking Download PDF

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CN111039884A
CN111039884A CN201911388724.7A CN201911388724A CN111039884A CN 111039884 A CN111039884 A CN 111039884A CN 201911388724 A CN201911388724 A CN 201911388724A CN 111039884 A CN111039884 A CN 111039884A
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acid
product
fluorescent whitening
whitening agent
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王真祥
董昕
弓振兴
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Shanxi Jinguang Chemical Co Ltd
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Shanxi Jinguang Chemical Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D251/00—Heterocyclic compounds containing 1,3,5-triazine rings
    • C07D251/02—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings
    • C07D251/12—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members
    • C07D251/26—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members with only hetero atoms directly attached to ring carbon atoms
    • C07D251/40—Nitrogen atoms
    • C07D251/54—Three nitrogen atoms
    • C07D251/70—Other substituted melamines
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/06—Luminescent, e.g. electroluminescent, chemiluminescent materials containing organic luminescent materials
    • 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
    • D21H21/30—Luminescent or fluorescent substances, e.g. for optical bleaching
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K2211/00—Chemical nature of organic luminescent or tenebrescent compounds
    • C09K2211/10—Non-macromolecular compounds
    • C09K2211/1003—Carbocyclic compounds
    • C09K2211/1007—Non-condensed systems
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K2211/00—Chemical nature of organic luminescent or tenebrescent compounds
    • C09K2211/10—Non-macromolecular compounds
    • C09K2211/1018—Heterocyclic compounds
    • C09K2211/1025—Heterocyclic compounds characterised by ligands
    • C09K2211/1059—Heterocyclic compounds characterised by ligands containing three nitrogen atoms as heteroatoms

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Abstract

The invention relates to a preparation method of a liquid fluorescent whitening agent for papermaking with stable quality, and aims to solve the technical problem of unstable product quality caused by unstable system pH in the production process of a bistriazine amino stilbene type tetrasulfonic acid fluorescent whitening agent. In the condensation reaction, the acid-binding agent and the reaction materials are added into the system by changing the adding mode of the acid-binding agent and adopting a fixed flow rate method, so that the influence of human factors on the product quality is reduced to the maximum extent, and the problem of unstable product quality is fundamentally solved; on the premise of ensuring the stable quality of raw materials, the liquid fluorescent whitening agent prepared by the invention has stable and reliable performance indexes of the final product, including enhanced whiteness, Ganz whiteness, chromatographic purity and the like, and the batch difference is controlled to be about +/-3-5%. The invention greatly simplifies the operation process without modifying the existing equipment, and the process is stable and reliable; the method is suitable for all processing processes of the tetrasulfonic acid whitening agent.

Description

Preparation method of liquid fluorescent whitening agent with stable quality for papermaking
Technical Field
The invention relates to a preparation method of a liquid fluorescent whitening agent for papermaking with stable quality.
Background
The whiteness of paper is an important quality index of various paper products such as writing, printing and the like. Residual lignin in the papermaking fiber raw material exists in a coloring system, so that the finished paper presents certain yellow light. In order to achieve satisfactory whiteness of paper and to increase the grade of paper products, some physical or chemical whitening treatment is required in the paper production process. In recent years, fluorescent whitening agents have been widely used in the paper industry due to a series of advantages such as small addition amount, low cost, no influence on paper characteristics, good whitening effect, and reduction of chemical consumption in the paper production process.
The bistriazine aminostilbene type fluorescent whitening agent is the earliest fluorescent whitening agent variety in research and application, is also the fluorescent whitening agent with the largest dosage in the paper making industry at present, and can be roughly divided into two, four and six sulfoacids according to the quantity of sulfonic acid groups contained in the compound. Among them, disulfonic acid type fluorescent whitening agents are mainly used for whitening paper pulp, but the water solubility is poor, and the disulfonic acid type fluorescent whitening agents are not suitable for producing products in liquid dosage form; the hexa-sulfonic acid product has good water solubility, but has poor whitening strength and low retention rate in the paper manufacturing process, so that the use amount of paper in unit yield is greatly increased, and the production cost is improved; the tetra-sulfonic acid product between the two products is better compatible with the advantages of the two products, ensures higher whiteness enhancing performance, and simultaneously has good water solubility which is very suitable for producing liquid dosage products, so that the tetra-sulfonic acid product can partially replace di-and hexa-sulfonic acid products in many occasions, wherein excellent tetra-sulfonic acid fluorescent whitening agents comprise C.I.220, C.I.210 and the like.
With the increasing demand of people for paper quality, the demand of various chemical additives in paper is continuously updated, and for fluorescent whitening agents, the actual demand mainly lies in the following directions: the whitening agent has the advantages of high whitening performance, less addition amount, stable quality, excellent performance, suitability for continuous operation and automatic addition, small environmental pollution and the like, wherein how to ensure the quality stability of products among batches is one of the most needed problems of whitening agent manufacturers. If the batch difference of the whitening agent products is too large, in order to ensure the consistency of the whiteness and the chromatic light of the paper products in the use process, the addition amount of the whitening agent needs to be continuously and finely adjusted, for a paper machine with higher automation degree, the addition amount can be automatically adjusted according to the whiteness of the paper, the influence is relatively small, but for most paper machines with insufficient automation degree, the addition amount of the whitening agent is manually adjusted by continuously detecting the whiteness and the chromatic light of the paper, and obviously unrealistic. At present, the batch output of most of commercially available liquid fluorescent whitening agents for papermaking is about 30 tons, and the problem of poor batch of products is solved by common manufacturers by a method of mixing multiple batches of products, mixing and stirring 15-20 batches of materials before packaging finished products, and eliminating the influence of poor batch as much as possible.
It is well known that the stability of product quality is mainly affected by the stability of raw materials and processes. The most important raw material in the production of fluorescent whitening agents is DSD acid (4, 4-diaminostilbene-2, 2-disulfonic acid), which is a hygroscopic yellow or pale yellow crystal and an important dye intermediate, and the whitening agent molecules have fluorescence properties due to the special chemical structure of the DSD acid. Whether the reaction conditions (pH and stability) of the DSD acid are stable and whether all the addition amount can sufficiently and completely participate in the reaction is the most critical factor for determining whether the quality of the final product can be stable in the production process of the fluorescent whitening agent. It is known that, during the reaction process, the DSD acid and cyanuric chloride, another main raw material, are continuously subjected to condensation reaction to generate hydrochloric acid, the continuous reduction of the system pH is not beneficial to the forward reaction, and at this time, an acid-binding agent needs to be added for neutralization to promote the reaction, so that on the premise that the flow rate of the DSD acid solution is relatively fixed, the flow rate of the acid-binding agent can greatly affect the change of the system pH, and how to control the flow rate of the acid-binding agent to stabilize the medium environment of the system and keep the medium environment in a range suitable for the DSD acid reaction is a great challenge for various manufacturers. At present, most manufacturers often control the reaction pH value manually according to the actual experience of operators, and due to different proficiency of the operators, the phenomenon that the pH value is suddenly high and suddenly low in the reaction process inevitably occurs, so that the DSD acid cannot react in a relatively stable system: once the pH is too low, DSD acid can be separated out from the system and is difficult to dissolve again and participate in the reaction; too high a pH causes hydrolysis of cyanuric chloride and also prevents condensation with DSD acid, and these instability factors are the most important causes of instability in the yield and quality of the final product.
CN105482488A reports a liquid fluorescent whitening agent special for printing and dyeing and papermaking industries and a synthesis process thereof, wherein a 30% sodium hydroxide solution is adopted as an acid-binding agent in the reaction process to adjust the pH value of a system to be between 5.0 and 5.5, the pH value of the system is unstable in the reaction process due to the over-strong alkalinity of the acid-binding agent, DSD acid is not easy to completely react, the stability of the product quality is finally influenced, and the control of the product quality and the industrial production are not facilitated.
CN1287200A reports a special liquid fluorescent whitening agent for the paper making industry and a synthesis process thereof, which comprises four steps of raw material refining, organic reaction, semi-finished product purification and refining and concentration. The raw materials are ground by using the vibrating screen for purification, the steps are complex, the treatment cost is high, the quality of the semi-finished product is not easy to stably control, and the quality of the final product can be influenced to a great extent.
CN102093750A reports a preparation method of a liquid fluorescent whitening agent with low temperature stability, which is to stir disulfonic acid fluorescent whitening agent dye, cellosolve, polyethylene glycol compounds, polyol compounds, urea and water uniformly, heat and dissolve, cool and filter to obtain the product. Although the method is simple to operate, the quality of the final product is easily influenced by the quality of the disulfonic acid fluorescent whitening agent, so that the quality of the final product fluctuates.
CN101654894A discloses a method for preparing a stilbene triazine liquid fluorescent whitening agent composition, which takes cyanuric chloride, sulfanilic acid, 4 '-diaminostilbene-2, 2' -disulfonic acid (DSD acid), morpholine and diethanolamine as raw materials to prepare the stilbene triazine liquid fluorescent whitening agent composition containing symmetry and asymmetry. The acid-binding agent used in the preparation process is 20-45% NaOH solution and Na2CO3In the addition process of the DSD acid, the problem of system pH fluctuation can also occur in the solution, so that the DSD acid is remained, and the stability of the quality of a final product is influenced.
In summary, in the production process of most of the liquid fluorescent whitening agents in China at present, the problem of unstable system pH generally exists because the addition speed and the addition amount of DSD acid and an acid-binding agent are controlled by the experience of operators, so that the DSD acid is not reacted completely and remains in a final product, the stability of the product quality is influenced, and the practical application of the whitening agent is limited to a certain extent. Therefore, it is very important to develop a process capable of stably controlling the product quality under the limitation of the existing personnel, equipment and automation degree.
Disclosure of Invention
The invention aims to solve the technical problem of unstable product quality caused by unstable system pH in the production process of a bistriazine aminostilbene type tetrasulfonic acid fluorescent whitening agent, and provides a preparation method of a liquid fluorescent whitening agent for papermaking with stable quality.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
a preparation method of a liquid fluorescent whitening agent for papermaking with stable quality comprises the following steps:
1) under the action of an acid-binding agent, cyanuric chloride and sulfanilic acid are subjected to a first-step condensation reaction to obtain a product I, namely 4- (4, 6-dichlorotriazine-2-amino) benzenesulfonic acid, wherein the structural formula is as follows:
Figure BDA0002344317160000041
2) adding 4, 4-diaminostilbene-2, 2-disulfonic acid into a NaOH solution with the concentration of 8-15%, mixing, and stirring until solid materials are completely dissolved until the solid materials are clear and bright to obtain a DSD-NaOH solution;
3) dripping the DSD-NaOH solution prepared in the step 2) into the product I prepared in the step 1) at a constant speed, and carrying out a second condensation reaction to obtain a product II, wherein the structural formula is as follows:
Figure BDA0002344317160000051
4) adding diethanolamine into the product II prepared in the step 3), and adding an acid-binding agent to obtain a compound III, wherein the structural formula is as follows:
Figure BDA0002344317160000052
5) and (2) stirring the reaction solution containing the compound III, cooling to below 55 ℃, performing suction filtration by using a Buchner funnel, removing water-insoluble impurities, and performing desalination and concentration on the filtrate by using a WTM-1812D type nanofiltration membrane at 30 ℃ and under the pressure of 1.2MPa to obtain the liquid fluorescent whitening agent for papermaking, which has stable quality.
Further, the acid-binding agent in the step 1) is 10% Na2CO3Solution or 10% NaOH solution.
Further, the acid-binding agent in the step 4) is NaOH solid.
Further, the preparation method of the liquid fluorescent whitening agent for papermaking with stable quality comprises the following specific steps:
1) according to the formula of cyanuric chloride, sulfanilic acid and 10% Na2CO3The molar ratio of the solution is 1.0: 1.15-1.25: 2.1-2.2, dispersing cyanuric chloride in ice water mixed solution, adding sulfanilic acid, and dripping 10% Na at constant speed2CO3The solution is used as an acid-binding agent, the pH value of a reaction system is slowly increased from 2.0-4.0 to 4.0-6.0, then a first-step condensation reaction is carried out at 0-10 ℃, and the reaction is carried out until the amino value disappears to obtain a product I;
2) according to the weight ratio of 4, 4-diaminostilbene-2, 2-disulfonic acid: adding 8-15% NaOH solution into 4, 4-diaminostilbene-2, 2-disulfonic acid according to the molar ratio of 1.0: 3.8-4.5, stirring until solid materials are completely dissolved to be clear and bright to obtain DSD-NaOH solution;
3) adding the DSD-NaOH solution prepared in the step 2) into the product I prepared in the step 1) at a constant speed to enable the pH value of a reaction system to be 6.0-7.0, then carrying out a second-step condensation reaction at 15-45 ℃ until the amino value disappears to obtain a product II;
4) according to product II: diethanolamine-1.0: 2.5-4.0, adding diethanolamine into the product II, and stirring for 0.1-1.0 h; according to the weight ratio of diethanolamine: NaOH solid 1.0: 0.6-0.8, adding NaOH solid into the reaction system at one time to slowly reduce the pH value of the system from 12.0-10.0 to 7.0-8.0, and carrying out a third condensation reaction at 80 ℃ until the pH value of the system is not changed to obtain a compound III;
5) and (2) stirring the reaction solution containing the compound III, cooling to below 55 ℃, performing suction filtration by using a Buchner funnel, removing water-insoluble impurities, and performing desalination and concentration on the filtrate by using a WTM-1812D type nanofiltration membrane at 30 ℃ and under the pressure of 1.2MPa to obtain the liquid fluorescent whitening agent for papermaking, which has stable quality.
Further, 10% of Na is dripped at a constant speed in the step 1)2CO3The solution is used as an acid-binding agent, and the dropping time is controlled within 2-4 h.
Further, in the step 3), DSD-NaOH solution is added into the product I at a constant speed, and the dropping time is 1.0-2.0 h.
The invention has the beneficial effects that:
aiming at the problem of unstable product quality caused by unstable system pH in the production process of the bistriazine amino stilbene type tetrasulfonic acid fluorescent whitening agent, the invention changes the adding mode of the acid-binding agent in the condensation reaction and adopts a fixed flow rate method to add the acid-binding agent and reaction materials into the system, thereby reducing the influence of human factors on the product quality to the maximum extent, fundamentally solving the problem of unstable product quality, and achieving the effective control of the whiteness of the finished paper by fixing the adding amount of the whitening agent in the process of using the whitening agent. The operation process is simple and easy, effectively avoids the fluctuation of the pH value of the system, is easy to stably control the product quality, and has the advantages that compared with the traditional process:
1. in the first step of condensation reaction, the flow rate of the acid-binding agent is fixed, the acid-binding agent with fixed dosage is completely added in a certain time, and experiments show that the pH value of the system can slowly and stably rise along with the reaction, and the pH value at the initial stage of the reaction is lower, so that the hydrolysis of cyanuric chloride can be reduced; the stability of the pH value in the middle reaction stage ensures the stable reaction, and the improvement of the pH value in the later reaction stage ensures the full reaction of the cyanuric chloride and the sulfanilic acid;
2. in the second step of condensation reaction, the acid-binding agent with thinner concentration and the DSD acid are mixed uniformly and added into the one-step condensation product within a certain time, which is the most important characteristic of the invention and is the biggest difference from the traditional process. Experiments show that the pH value of the reaction system is always stable at about 5.0-7.0, and no obvious fluctuation occurs, which indicates that the acid-binding agent is mixed with the DSD acid to ensure that the reaction with the one-step condensation product is also carried out under the condition of a stable medium, thereby ensuring that the DSD acid can fully and completely participate in the reaction and providing the basic elements of stable quality of final products; in the invention, the second condensation reaction is the most critical part in the whole reaction, the reactant (DSD acid) and the acid-binding agent are directly mixed and added into the reaction system at a constant speed, rather than the traditional mode of respectively adding the DSD acid and the acid-binding agent, the influence of human factors on the system medium environment is avoided, the pH value in the reaction process is effectively stabilized, the DSD acid is enabled to react under the relatively stable medium condition, the full and complete participation of the DSD acid in the reaction is ensured, and the key guarantee is provided for the stability of the quality of the final product.
3. In the third step of condensation reaction, the solid acid-binding agent is added at one time, the pH value of the system is slightly higher in the initial stage of the reaction, and the pH value is slowly reduced and gradually stabilized at 8.0-11.0 along with the reaction, because the reaction of the diethanolamine and the secondary condensation product requires the conditions of high temperature and high pH value, the reaction speed is slow, the initial high pH value can promote the reaction to be carried out towards the positive direction, and then the pH value is slowly reduced and kept stable, which shows that the reaction of the diethanolamine is also carried out under the condition of stable medium, thereby further ensuring the stability of the product quality.
4. The method adopts a nanofiltration membrane filtration mode to carry out post-treatment and processing on the product, replaces the traditional acid precipitation process with large wastewater amount, incomplete desalination and a salting-out process with multiple steps and serious raw material waste, utilizes the nanofiltration membrane with selective permeability to concentrate and desalt the target product under the push of a high-pressure pump, removes most of inorganic salts generated in the reaction process, obtains the liquid fluorescent whitening agent with good salt content and storage stability, and further ensures the stability of the product.
5. The liquid fluorescent whitening agent prepared by the invention is amber liquid and odorless, and has a maximum absorption wavelength of 349nm and a maximum fluorescence emission wavelength of 434 nm. On the premise of ensuring the stable quality of raw materials, all performance indexes of the final product are stable and reliable, including enhanced whiteness, Ganz whiteness, chromatographic purity and the like, and the batch difference is controlled to be about +/-3-5%. In the process of using in a paper mill, under the premise of stabilizing paper making raw materials such as paper pulp and the like, the using amount of a whitening agent is almost not required to be adjusted when the same paper-making whiteness is achieved, so that the stable operation of a paper machine system is effectively ensured, and the maximum problem of the tetrasulfonic acid liquid fluorescent whitening agent in the paper making process is solved; the method greatly simplifies the operation process on the premise of not modifying the existing equipment, reduces the influence of human factors on the final quality of the product to the maximum extent, and has stable and reliable process; meanwhile, the method is a universal method and is suitable for the processing process of all the tetrasulfonic acid whitening agents.
Detailed Description
The present invention will be further illustrated with reference to the following examples.
Example 1 preparation of a quality-Stable liquid optical brightener for papermaking
1) Adding 300g of crushed ice and 300g of water into a 2000ml beaker, cooling in an ice bath, adding 30g of cyanuric chloride into the beaker, stirring and pulping for 1.5 hours, and dispersing the cyanuric chloride into an ice water mixed solution. Then 30g of sulfanilic acid is added into the reaction system at one time, the mixture is stirred for 10min, and 180g of 10 percent Na is added2CO3Adding the solution into a reaction system at a constant speed within 2.5h, slowly increasing the pH value of the reaction system from 2.0-4.0 to 4.0-6.0, increasing the temperature of the reaction system from 5 ℃ to 10 ℃, carrying out a first-step condensation reaction until the amino value disappears, and obtaining a product I, namely 4- (4, 6-dichlorotriazine-2-amino) benzenesulfonic acid, wherein the structural formula is as follows:
Figure BDA0002344317160000091
2) adding 27g of DSD acid (4, 4-diaminostilbene-2, 2-disulfonic acid) into 120g of 10% NaOH solution, mixing and stirring until solid materials are completely dissolved until the solid materials are clear and bright to obtain a DSD-NaOH solution;
3) adding the DSD-NaOH solution prepared in the step 2) into the product I prepared in the step 1) at a constant speed within 1.5h, enabling the pH value of a reaction system to be 6.0-7.0, slowly increasing the temperature from 15 ℃ to 40 ℃, preserving the temperature for carrying out a second-step condensation reaction, and reacting until an amino value disappears to obtain a product II, wherein the structural formula is as follows:
Figure BDA0002344317160000092
4) adding 25g of diethanolamine into the reaction solution obtained in the step 3), and stirring for 0.1-1.0 h; and then adding 7.5g of NaOH solid into the reaction system at one time, slowly reducing the pH value of the system from 12.0-10.0 to 7.0-8.0, heating to 80 ℃ to carry out a third step of condensation reaction, and reacting until the pH value of the system is not changed, so as to obtain a compound III, wherein the structural formula is as follows:
Figure BDA0002344317160000093
5) stirring the reaction solution containing the compound III, cooling to below 55 ℃, performing suction filtration by using a Buchner funnel to remove water insoluble impurities, performing desalination and concentration on the filtrate by a WTM-1812D type nanofiltration membrane at the temperature of 30 ℃ and the pressure of 1.2MPa, and stopping nanofiltration when the conductivity is 550-300 mu S/cm (diluted by 200 times). Concentrating to a specified strength to obtain the liquid fluorescent whitening agent for papermaking with stable quality.
Example 2 preparation of a quality-Stable liquid optical brightener for papermaking
1) Adding 300g of crushed ice and 300g of water into a 2000ml beaker, cooling in an ice bath, adding 30g of cyanuric chloride into the beaker, stirring and pulping for 1.5 hours, and dispersing the cyanuric chloride into an ice water mixed solution. Then adding 30g of sulfanilic acid into the reaction system at one time, stirring for 10min, then adding 140g of 10% NaOH solution into the reaction system at a constant speed within 2.5h, slowly increasing the pH value of the reaction system from 2.0-4.0 to 4.0-6.0, increasing the temperature of the reaction system from 5 ℃ to 10 ℃, carrying out a first-step condensation reaction until the amino value disappears, and obtaining a product I, namely 4- (4, 6-dichlorotriazine-2-amino) benzenesulfonic acid, wherein the structural formula is as follows:
Figure BDA0002344317160000101
3) adding 27g of DSD acid (4, 4-diaminostilbene-2, 2-disulfonic acid) into 120g of 10% NaOH solution, mixing and stirring until solid materials are completely dissolved until the solid materials are clear and bright to obtain a DSD-NaOH solution;
3) adding the DSD-NaOH solution prepared in the step 2) into the product I prepared in the step 1) at a constant speed within 1.5h, enabling the pH value of a reaction system to be 6.0-7.0, slowly increasing the temperature from 15 ℃ to 40 ℃, preserving the temperature for carrying out a second-step condensation reaction, and reacting until an amino value disappears to obtain a product II, wherein the structural formula is as follows:
Figure BDA0002344317160000102
4) adding 25g of diethanolamine into the reaction solution obtained in the step 3), and stirring for 0.1-1.0 h; and then adding 7.5g of NaOH solid into the reaction system at one time, slowly reducing the pH value of the system from 12.0-10.0 to 7.0-8.0, heating to 80 ℃ to carry out a third step of condensation reaction, and reacting until the pH value of the system is not changed, so as to obtain a compound III, wherein the structural formula is as follows:
Figure BDA0002344317160000111
5) stirring the reaction solution containing the compound III, cooling to below 55 ℃, performing suction filtration by using a Buchner funnel to remove water insoluble impurities, performing desalination and concentration on the filtrate by a WTM-1812D type nanofiltration membrane at the temperature of 30 ℃ and the pressure of 1.2MPa, and stopping nanofiltration when the conductivity is 550-300 mu S/cm (diluted by 200 times). Concentrating to a specified strength to obtain the liquid fluorescent whitening agent for papermaking with stable quality.
Example 3 preparation of a quality-Stable liquid optical brightener for papermaking
1) Adding 300g of crushed ice and 300g of water into a 2000ml beaker, cooling in an ice bath, adding 30g of cyanuric chloride into the beaker, stirring and pulping for 1.5 hours, and dispersing the cyanuric chloride into an ice water mixed solution. Then 30g of sulfanilic acid is added into the reaction system at one time, the mixture is stirred for 10min, and 180g of 10 percent Na is added2CO3Adding the mixture into a reaction system at a constant speed within 4h, slowly increasing the pH value of the reaction system from 2.0-4.0 to 4.0-6.0, increasing the temperature of the reaction system from 5 ℃ to 10 ℃, and carrying out a first-step condensation reaction until the amino value disappears to obtain a product I, namely 4- (4, 6-dichlorotriazine-2-amino) benzenesulfonic acid, wherein the structural formula is as follows:
Figure BDA0002344317160000112
2) adding 27g of DSD acid (4, 4-diaminostilbene-2, 2-disulfonic acid) into 120g of 10% NaOH solution, mixing and stirring until solid materials are completely dissolved until the solid materials are clear and bright to obtain a DSD-NaOH solution;
3) adding the DSD-NaOH solution prepared in the step 2) into the product I prepared in the step 1) at a constant speed within 2.0h, enabling the pH value of a reaction system to be 6.0-7.0, slowly increasing the temperature from 15 ℃ to 40 ℃, preserving the temperature for carrying out a second-step condensation reaction, and reacting until an amino value disappears to obtain a product II, wherein the structural formula is as follows:
Figure BDA0002344317160000121
4) adding 25g of diethanolamine into the reaction solution obtained in the step 3), and stirring for 0.1-1.0 h; and then adding 7.5g of NaOH solid into the reaction system at one time, slowly reducing the pH value of the system from 12.0-10.0 to 7.0-8.0, heating to 80 ℃ to carry out a third step of condensation reaction, and reacting until the pH value of the system is not changed, so as to obtain a compound III, wherein the structural formula is as follows:
Figure BDA0002344317160000122
5) stirring the reaction solution containing the compound III, cooling to below 55 ℃, performing suction filtration by using a Buchner funnel to remove water insoluble impurities, performing desalination and concentration on the filtrate by a WTM-1812D type nanofiltration membrane at the temperature of 30 ℃ and the pressure of 1.2MPa, and stopping nanofiltration when the conductivity is 550-300 mu S/cm (diluted by 200 times). Concentrating to a specified strength to obtain the liquid fluorescent whitening agent for papermaking with stable quality.
Example 4 preparation of a quality-Stable liquid optical brightener for papermaking
1) Adding 300g of crushed ice and 300g of water into a 2000ml beaker, cooling in an ice bath, adding 30g of cyanuric chloride into the beaker, stirring and pulping for 1.5 hours, and dispersing the cyanuric chloride into an ice water mixed solution. Then 30g of sulfanilic acid is added into the reaction system at one time, the mixture is stirred for 10min, and 180g of 10 percent Na is added2CO3Adding the mixture into a reaction system at a constant speed within 2h, slowly increasing the pH value of the reaction system from 2.0-4.0 to 4.0-6.0, increasing the temperature of the reaction system from 5 ℃ to 10 ℃, and carrying out a first-step condensation reaction until the amino value disappears to obtain a product I, namely 4- (4, 6-dichlorotriazine-2-amino) benzenesulfonic acid, wherein the structural formula is as follows:
Figure BDA0002344317160000131
2) adding 27g of DSD acid (4, 4-diaminostilbene-2, 2-disulfonic acid) into 120g of 10% NaOH solution, mixing and stirring until solid materials are completely dissolved until the solid materials are clear and bright to obtain a DSD-NaOH solution;
3) adding the DSD-NaOH solution prepared in the step 2) into the product I prepared in the step 1) at a constant speed within 1.0h, enabling the pH value of a reaction system to be 6.0-7.0, slowly increasing the temperature from 15 ℃ to 40 ℃, preserving the temperature for carrying out a second-step condensation reaction, and reacting until an amino value disappears to obtain a product II, wherein the structural formula is as follows:
Figure BDA0002344317160000132
4) adding 25g of diethanolamine into the reaction solution obtained in the step 3), and stirring for 0.1-1.0 h; and then adding 7.5g of NaOH solid into the reaction system at one time, slowly reducing the pH value of the system from 12.0-10.0 to 7.0-8.0, heating to 80 ℃ to carry out a third step of condensation reaction, and reacting until the pH value of the system is not changed, so as to obtain a compound III, wherein the structural formula is as follows:
Figure BDA0002344317160000133
5) stirring the reaction solution containing the compound III, cooling to below 55 ℃, performing suction filtration by using a Buchner funnel to remove water insoluble impurities, performing desalination and concentration on the filtrate by a WTM-1812D type nanofiltration membrane at the temperature of 30 ℃ and the pressure of 1.2MPa, and stopping nanofiltration when the conductivity is 550-300 mu S/cm (diluted by 200 times). Concentrating to a specified strength to obtain the liquid fluorescent whitening agent for papermaking with stable quality.
The whitening effect of the whitening agent prepared in each example above was tested according to the relevant provisions of "assay for the whitening intensity and color of fluorescent whitening agents" in GB/T23979.2-2009.
Four samples were taken for each example, and a multi-batch repeat test was performed to perform an in-pulp addition test, and the whiteness and color of the finished paper were compared to examine the stability of the sample quality. The test data are as follows:
examples of the invention CIE whiteness L brightness a red green difference Difference of yellow and blue
Example 1 sample No. 1# 108.3 98.3 1.31 -0.84
EXAMPLE 1 sample No. 2# 108.1 98.2 1.30 -0.83
EXAMPLE 1 sample No. 3# 108.1 98.4 1.34 -0.83
Example 1 sample 4# 108.4 98.3 1.34 -0.84
Example 2 sample No. 1# 108.7 98.5 1.39 -0.80
Example 2 sample 2# 108.7 98.1 1.38 -0.82
Example 2 sample 3# 108.4 98.1 1.38 -0.82
Example 2 sample 4# 108.5 98.2 1.36 -0.83
Example 3 sample No. 1# 108.4 98.4 1.34 -0.83
Example 3 sample 2# 108.5 98.3 1.35 -0.84
Example 3 sample 3# 108.4 98.4 1.36 -0.83
Example 3 sample 4# 108.3 98.3 1.38 -0.82
Example 4 sample No. 1# 108.7 98.2 1.37 -0.83
Example 4 sample 2# 108.6 98.1 1.37 -0.80
Example 4 sample 3# 108.6 98.3 1.34 -0.82
Example 4 sample 4# 108.7 98.2 1.35 -0.84
From the above data it can be seen that the quality of the liquid fluorescent whitening agents prepared according to the present invention is stable with lot variation < + > 3%.
The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The above description is only a preferred embodiment of the present invention, and is not intended to limit the technical solutions of the present invention in any way. Any simple modification, equivalent change and modification of the above embodiments according to the technical spirit of the present invention fall within the scope of the present invention.

Claims (6)

1. A preparation method of a liquid fluorescent whitening agent for papermaking with stable quality is characterized by comprising the following steps: the method comprises the following steps:
1) under the action of an acid-binding agent, cyanuric chloride and sulfanilic acid are subjected to a first-step condensation reaction to obtain a product I, namely 4- (4, 6-dichlorotriazine-2-amino) benzenesulfonic acid, wherein the structural formula is as follows:
Figure FDA0002344317150000011
2) adding 4, 4-diaminostilbene-2, 2-disulfonic acid into a NaOH solution with the concentration of 8-15%, mixing, and stirring until solid materials are completely dissolved until the solid materials are clear and bright to obtain a DSD-NaOH solution;
3) dripping the DSD-NaOH solution prepared in the step 2) into the product I prepared in the step 1) at a constant speed, and carrying out a second condensation reaction to obtain a product II, wherein the structural formula is as follows:
Figure FDA0002344317150000012
4) adding diethanolamine into the product II prepared in the step 3), and adding an acid-binding agent to obtain a compound III, wherein the structural formula is as follows:
Figure FDA0002344317150000013
5) and (2) stirring the reaction solution containing the compound III, cooling to below 55 ℃, performing suction filtration by using a Buchner funnel, removing water-insoluble impurities, and performing desalination and concentration on the filtrate by using a WTM-1812D type nanofiltration membrane at 30 ℃ and under the pressure of 1.2MPa to obtain the liquid fluorescent whitening agent for papermaking, which has stable quality.
2. The preparation method of the papermaking liquid fluorescent whitening agent with stable quality according to claim 1, characterized in that: the acid-binding agent in the step 1) is 10% Na2CO3Solution or 10% NaOH solution.
3. The preparation method of the papermaking liquid fluorescent whitening agent with stable quality according to claim 1, characterized in that: the acid binding agent in the step 4) is NaOH solid.
4. The preparation method of the papermaking liquid fluorescent whitening agent with stable quality according to any one of claims 1 to 3, characterized by comprising the following steps:
1) according to the formula of cyanuric chloride, sulfanilic acid and 10% Na2CO3The molar ratio of the solution is 1.0: 1.15-1.25: 2.1-2.2, dispersing cyanuric chloride in ice water mixed solution, adding sulfanilic acid, and dripping 10% Na at constant speed2CO3The solution is used as an acid-binding agent, the pH value of a reaction system is slowly increased from 2.0-4.0 to 4.0-6.0, then a first-step condensation reaction is carried out at the temperature of 5-10 ℃, and the reaction is carried out until the amino value disappears to obtain a product I;
2) according to the weight ratio of 4, 4-diaminostilbene-2, 2-disulfonic acid: adding 8-15% NaOH solution into 4, 4-diaminostilbene-2, 2-disulfonic acid according to the molar ratio of 1.0: 3.8-4.5, stirring until solid materials are completely dissolved to be clear and bright to obtain DSD-NaOH solution;
3) adding the DSD-NaOH solution prepared in the step 2) into the product I prepared in the step 1) at a constant speed to enable the pH value of a reaction system to be 6.0-7.0, then carrying out a second-step condensation reaction at 15-45 ℃ until the amino value disappears to obtain a product II;
4) according to product II: diethanolamine-1.0: 2.5-4.0, adding diethanolamine into the product II, and stirring for 0.1-1.0 h; according to the weight ratio of diethanolamine: NaOH solid 1.0: 0.6-0.8, adding NaOH solid into the reaction system at one time to slowly reduce the pH value of the system from 12.0-10.0 to 7.0-8.0, and carrying out a third condensation reaction at 80 ℃ until the pH value of the system is not changed to obtain a compound III;
5) and (2) stirring the reaction solution containing the compound III, cooling to below 55 ℃, performing suction filtration by using a Buchner funnel, removing water-insoluble impurities, and performing desalination and concentration on the filtrate by using a WTM-1812D type nanofiltration membrane at 30 ℃ and under the pressure of 1.2MPa to obtain the liquid fluorescent whitening agent for papermaking, which has stable quality.
5. The preparation method of the papermaking liquid fluorescent whitening agent with stable quality according to claim 4, characterized in that: dripping 10% Na at constant speed in the step 1)2CO3The solution is used as an acid-binding agent, and the dropping time is controlled within 2-4 h.
6. The preparation method of the papermaking liquid fluorescent whitening agent with stable quality according to claim 4, characterized in that: and in the step 3), DSD-NaOH solution is added into the product I at a constant speed, and the dropping time is 1.0-2.0 h.
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114933702A (en) * 2022-06-20 2022-08-23 陕西科技大学 Preparation method and application of high-molecular fluorescent whitening agent
CN116004027A (en) * 2022-09-14 2023-04-25 河北三川化工有限公司 Stable acid-resistant whitening agent and preparation process thereof

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CN105482488A (en) * 2015-11-25 2016-04-13 山西青山化工有限公司 Liquid fluorescent whitener and preparation method thereof
CN106478536A (en) * 2016-08-31 2017-03-08 山西青山化工有限公司 A kind of preparation method of paper grade (stock) liquid fluorescent whitening agent

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Publication number Priority date Publication date Assignee Title
CN105482488A (en) * 2015-11-25 2016-04-13 山西青山化工有限公司 Liquid fluorescent whitener and preparation method thereof
CN106478536A (en) * 2016-08-31 2017-03-08 山西青山化工有限公司 A kind of preparation method of paper grade (stock) liquid fluorescent whitening agent

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114933702A (en) * 2022-06-20 2022-08-23 陕西科技大学 Preparation method and application of high-molecular fluorescent whitening agent
CN114933702B (en) * 2022-06-20 2023-06-27 陕西科技大学 Preparation method and application of high-molecular fluorescent whitening agent
CN116004027A (en) * 2022-09-14 2023-04-25 河北三川化工有限公司 Stable acid-resistant whitening agent and preparation process thereof

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