High-concentration superfine anthraquinone cooking aid and preparation method thereof

Abstract

The application provides a high-concentration superfine anthraquinone cooking aid, which comprises the following components in parts by weight: 10-15 parts of sulfonated anthraquinone, 15-25 parts of anthraquinone, 2-8 parts of sodium hyposulfite, 1.0-2.0 parts of wetting agent, 0.5-2.0 parts of dispersing agent, 0.2-0.8 parts of defoaming agent, 0.5-2.0 parts of NaOH, 0.5-1.5 parts of xanthan gum, 0.5-1.0 parts of ethyl hydroxyethyl cellulose, 0.1-0.3 parts of preservative and 50-65 parts of water. The application further provides a preparation method of the high-concentration superfine anthraquinone cooking aid, which specifically comprises the following steps: S1, pre-dispersion and alkalization reaction; S2, emulsification and dispersion; S3, suspension agent compounding; S4, fine grinding; S5, suspension stabilization; and the like. The high-concentration superfine anthraquinone cooking aid prepared by the application has the advantages of excellent suspension stability in a high-concentration state and smaller particle size to realize efficient penetration and catalysis.

Description

Technical Field

[0001] This invention relates to the field of pulping chemistry, specifically to a high-concentration, ultrafine anthraquinone cooking aid and its preparation method. Background Technology

[0002] Anthraquinone (AQ), as a highly efficient cooking aid, has been widely used in the pulp and paper industry. Its mechanism of action is as a redox catalyst, protecting cellulose and hemicellulose from alkaline degradation during cooking while accelerating the delignification reaction, thereby improving pulp yield and quality, and reducing energy and chemical consumption. However, traditional anthraquinone cooking aids still face many challenges in practical applications: (1) Poor solubility and dispersibility: Traditional anthraquinones have limited solubility and dispersibility in water or alkaline solutions, and often require high temperature or strong alkaline environment to dissolve well. When preparing high-concentration working solutions, anthraquinone particles are very easy to settle and agglomerate, resulting in uneven drug concentration, which affects the accuracy of addition and the effect of use.

[0003] (2) Insufficient stability: Especially at high concentrations, long-term storage can easily lead to stratification, precipitation, flocculation, etc., resulting in uneven distribution of effective ingredients and affecting their efficiency in the cooking process.

[0004] (3) There is still room for improvement in cooking efficiency: Although traditional anthraquinone adjuvants are effective, they still have potential in promoting the rapid penetration of the drug solution into the fiber and further increasing the delignification rate. Ultrafine particle size is considered an effective method because smaller particle size can increase the reaction surface area. However, ultrafine anthraquinone particles face serious agglomeration problems. How to maintain their ultrafine state and long-term stability in high-concentration suspensions is a key challenge.

[0005] To address the above problems, the following technical solutions have emerged in the existing technology: A common approach is to ultrafine anthraquinone into a dry powder, then mix it with a dispersant and a suspending agent to produce a dry powder form of easily dispersible anthraquinone. When used, the paper mill adds water on-site to prepare a slurry. However, this approach has the following drawbacks: (1) the dry powder product after ultrafine dry grinding is prone to moisture absorption and clumping during transportation and storage; (2) the on-site preparation is cumbersome, and the preparation effect is greatly affected by the operating conditions; (3) the paper mill still needs to have dedicated preparation equipment and operators for this product.

[0006] Another approach is to use a chemical conversion method, which reacts anthraquinone with a reducing agent in an alkaline environment to convert it into soluble anthraquinone, thereby obtaining a uniformly dispersed cooking aid. However, this method requires the reaction to be carried out at high temperatures (usually above 95°C), making the process more complex and energy-intensive. Furthermore, the reducing agent introduced during the chemical conversion process may have an adverse effect on pulp properties.

[0007] In addition, existing anthraquinone emulsion products typically have low anthraquinone solids concentrations, only 15-25%, and the anthraquinone particles in these products have relatively large particle sizes (D50 is usually 8-15μm), resulting in less than ideal dispersibility and poor stability in alkaline cooking liquor, which limits further improvement in the efficacy of the adjuvant.

[0008] Therefore, developing an anthraquinone cooking aid with high anthraquinone solid content, ultra-fine anthraquinone particle size, good suspension stability, and simple preparation process that does not require high-temperature treatment is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0009] This invention aims to overcome the technical shortcomings of existing anthraquinone cooking aids, such as poor solubility and dispersibility, insufficient storage stability, and limited improvement in cooking efficiency. It provides a high-concentration, ultrafine anthraquinone cooking aid with excellent stability and its preparation method. This aid significantly improves the permeability of the cooking solution, increases delignification efficiency, and is convenient for storage, transportation, and use.

[0010] To achieve the above technical solution, the present invention provides a high-concentration ultrafine anthraquinone cooking aid, comprising the following raw material components by weight: 10-15 parts sulfonated anthraquinone, 15-25 parts anthraquinone, 2-8 parts sodium dithionite, 1.0-2.0 parts wetting agent, 0.5-2.0 parts dispersant, 0.2-0.8 parts defoamer, 0.5-2.0 parts NaOH, 0.5-1.5 parts xanthan gum, 0.5-1.0 parts ethyl hydroxyethyl cellulose, 0.1-0.3 parts preservative, and 50-65 parts water.

[0011] In the above technical solution, by compounding sulfonated anthraquinone with anthraquinone and combining it with the reducing effect of sodium dithionite, the water solubility of the sulfonation product is utilized, and the partially water-soluble anthraquinone (AHQ) is generated, synergistically and significantly improving the solubility and dispersibility of the anthraquinone component in the aqueous system. The addition of wetting agents, dispersants, and defoamers aims to optimize the interfacial properties of the system and prevent foaming and agglomeration; while the suspension system of xanthan gum and ethyl hydroxyethyl cellulose provides excellent long-term storage stability for the final product and prevents the sedimentation of ultrafine particles. This synergistic formulation successfully prepared a high-concentration, stable, and highly active anthraquinone cooking aid with a solid content of 30-35 wt%.

[0012] Preferably, by weight, the sulfonated anthraquinone comprises 12 parts, anthraquinone 18 parts, and sodium dithionite 5 parts. This defines an optimal ratio of sulfonated anthraquinone (12 parts), anthraquinone (18 parts), and sodium dithionite (5 parts). This ratio ensures sufficient anthraquinone conversion to generate effective anthraquinone, improving water solubility and catalytic activity, while retaining an appropriate amount of unconverted ultrafine anthraquinone particles as the solid phase for subsequent grinding and suspension. The synergistic effect of these two factors achieves optimal cooking effect and system stability.

[0013] Preferably, the wetting agent is octylphenol polyoxyethylene ether, in parts by weight of 1.3. The wetting agent is specifically octylphenol polyoxyethylene ether (OP-10), whose excellent wetting and penetrating properties, combined with subsequent fine grinding processes, can effectively coat and modify the surface of anthraquinone particles, reducing their surface energy and preventing particle agglomeration. Simultaneously, it enhances the penetration ability of the additives in raw materials such as wood chips, thereby improving cooking efficiency.

[0014] Preferably, the dispersant is sodium dodecylbenzenesulfonate, in parts by weight of 0.6. Sodium dodecylbenzenesulfonate (SDBS), an anionic surfactant, provides strong electrostatic repulsion and can combine with the physical wetting action of the wetting agent octylphenol polyoxyethylene ether, further ensuring the dispersion stability of ultrafine particles in the liquid phase after fine grinding and preventing particle size rebound.

[0015] Preferably, the defoamer is polyether-modified silicone oil, in parts by weight of 0.4. Polyether-modified silicone oil can effectively eliminate foam generated during high-speed stirring, grinding, and surfactant introduction, ensuring the stability of the entire preparation process, especially the liquid level control and pumping process, and avoiding the reduction in effective concentration and suspension stability caused by excessive bubbles in the finished product.

[0016] Preferably, the preservative is 2-methylbenzisothiazolinone, in parts by weight of 0.2. 2-Methylbenzisothiazolinone (MIT) is highly efficient and low in toxicity, making it suitable for aqueous systems. It effectively inhibits microbial growth and extends the stability and shelf life of the additives of this invention (especially those containing natural high-molecular-weight xanthan gum) during storage.

[0017] This invention also provides a method for preparing a high-concentration ultrafine anthraquinone cooking aid, specifically including the following steps: S1. Pre-dispersion and alkalization reaction: Take 10-15 parts of sulfonated anthraquinone and 15-25 parts of anthraquinone according to the formula, dilute with water, and add 0.5-2.0 parts of NaOH and 2-8 parts of sodium dithionite in sequence while stirring. Stir and react at room temperature for 15-30 minutes to convert some anthraquinone into anthraquinone. S2. Emulsification and dispersion: Add 1.0-2.0 parts wetting agent, 0.5-2.0 parts dispersant, 0.2-0.8 parts defoamer and 0.1-0.3 parts preservative to the above system in sequence, and stir thoroughly to form a stable emulsion; S3, Suspension agent compounding: Dissolve 0.5-1.5 parts xanthan gum and 0.5-1.0 parts ethyl hydroxyethyl cellulose separately in water, and then compound them into a suspension agent at an oven-dry weight ratio of 1:1 to 2:1. S4. Fine grinding: The obtained emulsion is finely ground until the particle size D50 < 2μm and D90 < 10μm. S5. Suspension stability: Add the pre-mixed xanthan gum and ethyl hydroxyethyl cellulose compound suspending agent to the ground material, and stir thoroughly until uniformly dispersed to form a uniform and stable high-concentration suspension.

[0018] In the above technical solution, this preparation method systematically solves the technical difficulties in the preparation of traditional anthraquinone adjuvants through a step-by-step process of "chemical conversion + physical emulsification + fine grinding + suspension stabilization". Step S1 is carried out under alkalization and reduction conditions at room temperature and controlled pH, resulting in a mild reaction and avoiding the energy consumption and safety risks caused by high temperature and high pressure. The fine grinding step in step S4 achieves an ultrafine particle size of D50 < 2 μm and D90 < 10 μm, which greatly increases the specific surface area of ​​the particles and the reactivity, solving the problems of slow dissolution, low catalytic efficiency and easy scaling caused by the coarse particles of traditional AQ. Step S5 uses a "xanthan gum-ethyl hydroxyethyl cellulose" compound suspension technology, in which xanthan gum provides high shear thinning properties for easy pumping, and ethyl hydroxyethyl cellulose provides long-term static stability. The two work together to solve the problems of easy sedimentation and agglomeration of high-concentration ultrafine particle suspensions, so that the final product has both high activity and high stability.

[0019] Preferably, in step S1, the pH of the system is controlled to be maintained between 6.0 and 8.0, with no foaming. This provides a suitable alkaline and mild environment for the reduction of anthraquinone by sodium dithionite, avoids excessive alkalinity from corroding the equipment, and suppresses side reactions and excessive foaming, which is beneficial for obtaining a stable intermediate product.

[0020] Preferably, in step S4, fine grinding is performed using a sand mill or a ball mill, with zirconia beads as the grinding media. This grinding method can achieve efficient and uniform nano- to micron-level pulverization, and is particularly suitable for grinding partially converted AQ / AHQ solid particles together with a liquid system into a uniform ultrafine emulsion / suspension.

[0021] Preferably, in step S5, the solids concentration in the high-concentration suspension is controlled to be 30-35%. This concentration ensures both the content of active ingredients per unit volume (high concentration) and the ability of the xanthan gum / ethyl hydroxyethyl cellulose composite suspension system to form a sufficiently strong three-dimensional network structure at this concentration, thereby giving the product excellent long-term static stability and shear recovery, facilitating industrial storage, transportation, and pumping.

[0022] The beneficial effects of the high-concentration ultrafine anthraquinone cooking aid and its preparation method provided by this invention are as follows: (1) The high-concentration ultrafine anthraquinone cooking aid provided by the present invention, through the unique combination of sulfonated anthraquinone, anthraquinone compound and the reducing effect of sodium dithionite, and in combination with the wetting and dispersion system and xanthan gum / ethyl hydroxyethyl cellulose composite suspension technology, achieves a solid content of up to 30-35% of active ingredients, which is significantly higher than the general solid content level of 15-23% of existing anthraquinone emulsion products. It can form a stable suspension without hard sedimentation for a long time (≥6 months) and can be restored to a uniform state with slight shaking, which is significantly better than similar products on the market.

[0023] (2) The present invention uses a fine grinding process to make the active particles reach the submicron to micron level (D50 < 2μm), which is much smaller than the D50 of ordinary anthraquinone emulsion in the prior art (8-15μm). This greatly increases the reaction contact area. Combined with the penetration effect of the wetting agent, it can enter the interior of plant fibers faster and deeper, accelerate the delignification process, shorten the cooking time, and improve pulp yield and quality.

[0024] (3) The present invention adopts a process route of grinding first and then adding suspending agent to ensure that the anthraquinone particles reach an ultrafine particle size before being suspended and stabilized by xanthan gum / ethyl hydroxyethyl cellulose composite suspension technology, which effectively prevents the agglomeration and sedimentation of ultrafine particles. The resulting product has good suspension stability and can be directly used in the pulping and cooking process without the need for on-site mixing in paper mills, thus simplifying the operation process.

[0025] (4) The entire process of this invention is carried out at room temperature, without heating, and has low energy consumption; no organic solvents are required, making it environmentally friendly; the process steps are simple, the operation is convenient, and it is suitable for industrial-scale production. Attached Figure Description

[0026] Figure 1 This is a flowchart of the preparation method of the present invention. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention. Unless otherwise specified, all raw materials, reagents, instruments, and equipment used in the present invention can be purchased from the market or prepared by existing methods. Example 1

[0028] A high-concentration, ultrafine anthraquinone cooking aid is prepared according to the following components and steps: (1) Raw material preparation (parts by weight): 12 parts sulfonated anthraquinone, 18 parts anthraquinone, 5 parts sodium dithionite, 1.3 parts octylphenol polyoxyethylene ether (wetting agent), 0.6 parts sodium dodecylbenzenesulfonate (dispersant), 0.4 parts polyether modified silicone oil (defoamer), 1 part NaOH, 1 part xanthan gum, 0.5 parts ethyl hydroxyethyl cellulose, 0.2 parts 2-methylbenzisothiazolinone (preservative), 60 parts deionized water.

[0029] (2) Preparation method: S1. Pre-dispersion and alkalization reaction: Add 50 parts of deionized water to a stirred tank, start stirring, and slowly add 18 parts of anthraquinone powder and 12 parts of sulfonated anthraquinone, stirring until a slurry is formed. Then add 1 part of NaOH and 5 parts of sodium dithionite in sequence, and continue stirring at room temperature for 25 minutes. During this time, monitor and control the pH of the system at around 7.0. No foam is generated during the reaction, and a brownish-red mixture is obtained.

[0030] S2, Emulsification and Dispersion: Add 1.3 parts of octylphenol polyoxyethylene ether (wetting agent), 0.6 parts of sodium dodecylbenzenesulfonate (dispersant), 0.4 parts of polyether modified silicone oil (defoamer), and 0.2 parts of 2-methylbenzisothiazolinone (preservative) to the reaction solution of S1 in sequence, and stir at high speed for 30 minutes to form a uniform and stable dark emulsion.

[0031] S3. Suspension agent compounding: In a separate container, dissolve 1 part xanthan gum and 0.5 parts ethyl hydroxyethyl cellulose separately in the remaining 10 parts water by heating. After cooling to room temperature, mix them evenly to form a suspension agent for later use.

[0032] S4. Fine Grinding: The emulsion obtained in S2 is transferred to a sand mill, and zirconia beads with a particle size of 0.8 mm are used as the grinding media for circulating grinding. The particle size distribution of the material is controlled at the end of the grinding process to be D50=1.5μm and D90=8.2μm.

[0033] S5. Suspension Stability: Transfer the material ground in S4 to the final product reactor. While stirring at a medium speed, slowly add the xanthan gum and ethyl hydroxyethyl cellulose suspension solution prepared in S3. After the addition is complete, continue stirring for 60 minutes until the system is completely homogeneous, forming a pale yellow, highly concentrated suspension with good flowability. The solid content of the final product is approximately 31%.

[0034] The resulting product was observed after being sealed and left to stand at room temperature for 30 days. There was no clear liquid layer at the top and no hard precipitate at the bottom. It could be restored to a uniform suspension state with slight shaking, meeting the requirements for high concentration stability. Example 2

[0035] A high-concentration, ultrafine anthraquinone cooking aid is prepared according to the following components and steps: (1) Raw material preparation (parts by weight): 15 parts of sulfonated anthraquinone, 20 parts of anthraquinone, 6 parts of sodium dithionite, 1.5 parts of octylphenol polyoxyethylene ether (wetting agent), 0.8 parts of sodium dodecylbenzenesulfonate (dispersant), 0.5 parts of polyether modified silicone oil (defoamer), 1 part of NaOH, 1 part of xanthan gum, 1 part of ethyl hydroxyethyl cellulose, 0.2 parts of 2-methylbenzisothiazolinone (preservative), and 53 parts of deionized water.

[0036] (2) Preparation method: S1. Pre-dispersion and alkalization reaction: Add 45 parts of deionized water to a stirred tank, start stirring, and slowly add 20 parts of anthraquinone powder and 15 parts of sulfonated anthraquinone, stirring until a slurry is formed. Then add 1 part of NaOH and 6 parts of sodium dithionite in sequence, and continue stirring at room temperature for 25 minutes. During this period, monitor and control the pH of the system at around 7.0. No foam is generated during the reaction, and a brownish-red mixture is obtained.

[0037] S2, Emulsification and Dispersion: Add 1.5 parts of octylphenol polyoxyethylene ether (wetting agent), 0.8 parts of sodium dodecylbenzenesulfonate (dispersant), 0.5 parts of polyether modified silicone oil (defoamer), and 0.2 parts of 2-methylbenzisothiazolinone (preservative) to the reaction solution of S1 in sequence, and stir at high speed for 30 minutes to form a uniform and stable dark emulsion.

[0038] S3. Suspension agent compounding: In a separate container, dissolve 1 part xanthan gum and 1 part ethyl hydroxyethyl cellulose separately in the remaining 8 parts water by heating. After cooling to room temperature, mix them evenly to form a suspension agent for later use.

[0039] S4. Fine Grinding: The emulsion obtained in S2 is transferred to a sand mill, and zirconia beads with a particle size of 0.8 mm are used as the grinding media for circulating grinding. The particle size distribution of the material is controlled at the end of the grinding process to be D50=1.5μm and D90=8.2μm.

[0040] S5. Suspension Stability: Transfer the material ground in S4 to the final product reactor. While stirring at a medium speed, slowly add the xanthan gum and ethyl hydroxyethyl cellulose suspension solution prepared in S3. After the addition is complete, continue stirring for 60 minutes until the system is completely homogeneous, forming a pale yellow, highly concentrated suspension with good flowability. The solid content of the final product is approximately 35%.

[0041] The resulting product was observed after being sealed and left to stand at room temperature for 30 days. There was no clear liquid layer at the top and no hard precipitate at the bottom. It could be restored to a uniform suspension state with slight shaking, meeting the requirements for high concentration stability.

[0042] Comparative Example 1 The formulation uses 30 parts of anthraquinone, without adding sulfonated anthraquinone, and the rest of the formulation and preparation steps are the same as in Example 1.

[0043] In actual production, due to the extreme hydrophobicity of the surface of ordinary anthraquinone powder, without sulfonated anthraquinone as a "bridge," the reduction reaction only occurs on the very surface of the particles after adding NaOH and sodium dithionite. Because of the lack of negative charge repulsion from the sulfonate groups, the anthraquinone particles agglomerate in the aqueous phase. After stirring and dispersing, the slurry appears as a grayish-brown viscous mass, rather than the brownish-red flowing mixture in Example 1.

[0044] The product was observed after being sealed and left to stand at room temperature for 30 days. A small amount of clear liquid layer was found at the top (accounting for about 10% to 15% of the total volume), and there was no hard sediment at the bottom. It could only be restored to a uniform suspension state after vigorous shaking, which could not fully meet the requirements for high concentration stability.

[0045] Comparative Example 2 The formulation uses 30 parts of sulfonated anthraquinone, without adding anthraquinone, and the rest of the formulation and preparation steps are the same as in Example 1.

[0046] In actual production, sulfonated anthraquinones have excellent water solubility, dissolving quickly or forming colloids upon contact with water. With the addition of sodium dithionite, the reduction reaction is completed instantaneously in a homogeneous or near-homogeneous state, rapidly turning the solution a deep brownish-red color without any suspended particles. The system essentially becomes a "dye solution" rather than a "slurry." Furthermore, since sulfonated anthraquinones mostly exist in dissolved or microcrystalline form, when fed into a sand mill, the zirconia beads face a liquid medium rather than solid particles, resulting in significant energy wastage and an undefined grinding endpoint. After 30 days of settling, the resulting product shows no clear liquid layer at the top, but a fine, sludge-like soft precipitate (recrystallized particles) appears at the bottom. Although there are no hard lumps, the crystals have grown after shaking, making it difficult to restore the initial fine and uniform state, and the system color lightens.

[0047] Comparative Example 3 The same formulation as in Example 1 is used, but the fine grinding operation in step S4 is omitted, i.e., the suspension solution is added directly after coarse mixing and emulsification.

[0048] The anthraquinone particles in the obtained product have a large particle size (D50 is about 18μm), and obvious stratification and precipitation occur after standing for 24 hours, indicating poor suspension stability.

[0049] Comparative Example 4 The same formulation and steps as in Example 1 were followed, but the order of steps S4 and S5 was reversed, i.e., the suspending agent solution was added first and then the grinding was performed.

[0050] The viscosity of the resulting product increases significantly during the grinding process, and the grinding efficiency decreases. The grinding time needs to be extended by more than 2 times in order to achieve the target particle size of D50 < 2μm.

[0051] Comparative Example 5 No xanthan gum was added to the formulation, and no xanthan gum was added in step S3. The rest of the formulation and preparation steps were the same as in Example 1.

[0052] After standing for 30 days, the resulting product showed obvious hard precipitates at the bottom and a small amount of clear liquid at the top. Even with shaking, the hard lumps were difficult to completely redisperse evenly. The possible reason is that xanthan gum is an anionic polysaccharide with strong pseudoplasticity (shear thinning) and a high yield value. In a static state, its three-dimensional network structure formed by its molecular chains provides sufficient dynamic yield stress to support ultrafine anthraquinone particles (D50=1.5μm) with a density much greater than water. Comparative Example 3, relying solely on 0.5 parts of ethyl hydroxyethyl cellulose (EHEC), had a viscosity at low shear rates much lower than xanthan gum, resulting in insufficient yield value to resist gravity sedimentation. Furthermore, lacking the coating and steric stabilizing effect of xanthan gum, the high specific surface area ultrafine particles after grinding were highly prone to flocculation under Brownian motion and van der Waals forces. After small particles flocculated into large particles, the settling speed increased dramatically, and under gravity, they were continuously compacted, forming dense, "wet cake" hard lumps. Without the elastic network support provided by xanthan gum, this hard lump is difficult to resuspend by simple shaking.

[0053] Comparative Example 6 The formulation does not include 0.5 parts of ethyl hydroxyethyl cellulose, and step S3 does not include 0.5 parts of ethyl hydroxyethyl cellulose. The remaining formulation and preparation steps are the same as in Example 1.

[0054] After standing for 30 days, no hard precipitate formed at the bottom (because xanthan gum was still present), but a thick layer of clear liquid precipitated at the top (i.e., stratification / dehydration shrinkage), and the overall fluidity of the system may have deteriorated. The possible reason is that ethyl hydroxyethyl cellulose (EHEC) is a non-ionic water-soluble polymer with extremely strong hydrophilicity and water retention capacity, which can bind a large amount of free water, increasing the viscosity of the continuous phase. Without EHEC, although the xanthan gum network can suspend solid particles, its own gel network undergoes dehydration shrinkage during long-term standing, squeezing out the bound free water from the gel network, resulting in a large amount of clear liquid precipitating at the top. Moreover, the solid content of this system is as high as approximately 31%, classifying it as a high-concentration suspension system. As an auxiliary suspending agent, one of the functions of EHEC is to fill the pores of the xanthan gum network and adjust the density matching between the continuous and dispersed phases. Without EHEC, the viscosity of the continuous phase decreases significantly, and although the high-density anthraquinone particles do not settle to the bottom, they will "collapse" downwards under their own gravity, squeezing out the upper aqueous phase, thus causing severe stratification at the top.

[0055] The data from Examples 1, 5, and 6 show that xanthan gum and ethyl hydroxyethyl cellulose constitute a synergistic dual suspension system in the compound suspension system: xanthan gum is responsible for solving the "hard sediment at the bottom" problem (verified in Comparative Example 5); ethyl hydroxyethyl cellulose is responsible for solving the "water separation / stratification at the top" problem (verified in Comparative Example 6). Both are indispensable; using either alone will result in the final product failing to meet the stringent stability requirements of "no clear liquid at the top, no hard lumps at the bottom, and recovery upon slight shaking."

[0056] Application Example: Cooking Effect Test The high-concentration, ultrafine anthraquinone cooking aid obtained in Example 1 was added to the sulfate pulp cooking system at an effective anthraquinone dosage of 0.08% of the oven-dry raw material. The cooking conditions were: good quality eucalyptus chips, alkali dosage of 14.5%, 15.5%, and 16.0% (calculated as Na2O), liquor ratio of 1:4, maximum temperature of 165℃, heating time of 120 min, and holding time of 120 min. A control group and a commercially available aid group were compared. The commercially available aid was anthraquinone-based QY-Z1 produced by Weihai Weineng Chemical Co., Ltd.

[0057] After cooking, the cooking yield (the proportion of fiber retained, the higher the value, the better the raw material utilization) and kappa value (reflecting the degree of wood pulp delignification, the lower the value, the more complete the delignification) were measured, as shown in Table 1. Table 1. Cooking Effect Table

[0058] As can be seen from the data in Table 1: (1) Particle size comparison analysis: The self-made ultrafine anthraquinone has a D50 of 1.512 μm; the commercially available QY-Z1 has a D50 of 10.377 μm. The particle size of the self-made product is only about 1 / 7 of that of the commercially available adjuvant. Anthraquinone adjuvants rely on penetrating into the cell wall of wood chips to react with lignin. The smaller the particle size, the larger the specific surface area, the stronger the dispersibility and permeability in the alkaline cooking solution, and the higher the efficiency of contact reaction with lignin. This is the core reason for the advantages in subsequent delignification and yield retention.

[0059] (2) Analysis of Ka values ​​(delignification capacity): The lower the Ka value, the better the delignification effect, and the higher the pulp cleanliness under the same alkali conditions, which can reduce the consumption of subsequent bleaching chemicals. From the data of the blank group (without anthraquinone adjuvant), it can be seen that simply increasing the alkali content only slightly reduces the Ka value, and delignification is seriously insufficient under low alkali conditions; without anthraquinone catalysis, the alkali solution has low efficiency in degrading lignin, and a large amount of residual lignin adheres to the fiber. Comparison between the commercially available QY-Z1 group and the blank: the Ka values ​​under the same alkali conditions are all lower than the blank, proving that QY-Z1 anthraquinone has the standard catalytic delignification effect; however, the Ka values ​​in the 15.5% and 16.0% high alkali ranges are almost the same as the blank, the catalytic enhancement effect is weak under high alkali conditions, the penetration of large anthraquinone particles is limited, and the catalytic gain decreases rapidly with the increase of alkali content. Compared with the control group, the self-made ultrafine anthraquinone adjuvant group showed a significant decrease in kappa value across all three alkali levels, with the largest decrease in the low alkali range (14.5%), from 18.9 to 15.8, indicating that the ultrafine anthraquinone exhibits extremely strong catalytic advantages under low alkali conditions. Compared with the commercially available QY-Z1 adjuvant: at 14.5% low alkali: QY-Z1 Ka=17.7, while the self-made one is only 15.8, demonstrating a significantly better delignification effect; at 15.5% medium alkali: QY-Z1 Ka=16.6, while the self-made one is 15.0, with the gap widening further; at 16.0% high alkali: QY-Z1 Ka=15.7, while the self-made one is 14.3, maintaining a stable advantage. Regardless of low, medium, or high alkali levels, the self-made ultrafine anthraquinone consistently outperformed Weihai Weineng QY-Z1 in delignification; the high penetration and high reactivity resulting from the finer particle size were effective across the entire cooking alkalinity range.

[0060] (3) Analysis of cooking yield results (fiber retention, raw material economy): Cooking yield represents the proportion of fiber retained after cooking. The higher the yield, the more pulp is produced from the same amount of wood chips, and the lower the raw material cost. One of the core functions of anthraquinone adjuvants is to inhibit the alkaline degradation of cellulose, protect fibers, and improve yield. From the yield data of the blank group, it can be seen that: without anthraquinone, as the alkali used increases, cellulose degrades in large quantities, the yield continues to decline, and fiber loss is serious during high-alkali cooking. Comparison of yield of commercially available QY-Z1 group with blank: the yield of all three alkali levels is higher than that of the blank, proving that QY-Z1 can inhibit fiber degradation; however, the increase in yield is limited as the alkali used increases, and the yield of the 15.5% alkali level declines significantly, indicating that the fiber protection ability is average. The yield of self-made ultrafine anthraquinone adjuvant group relative to the blank: the yield of all three levels is improved, and the decline in yield under high-alkali conditions is much smaller than that of the blank. Compared to commercially available QY-Z1 additives: 14.5% low alkali: self-made 49.33% > QY-Z1 48.05%; 15.5% medium alkali: self-made 48.78% > QY-Z1 47.26%, the difference is significantly larger; 16.0% high alkali: self-made 48.92% > QY-Z1 47.38%. The possible reasons are: ultrafine anthraquinones can quickly and evenly disperse inside the wood chips, comprehensively encapsulating cellulose and effectively blocking the degradation of carbohydrates by high-temperature strong alkali; compared to large-particle QY-Z1, the fiber protection effect is stronger, the pulp yield is more stable and higher, and factories can reduce wood chip consumption and improve economic efficiency.

[0061] This invention employs a process route of grinding followed by adding a suspending agent to ensure that the anthraquinone particles reach an ultrafine particle size before being suspended and stabilized using xanthan gum / ethyl hydroxyethyl cellulose composite suspension technology. This effectively prevents the aggregation and sedimentation of ultrafine particles. The resulting product exhibits excellent suspension stability and can be directly used in the pulping and cooking process, eliminating the need for on-site mixing at the paper mill and simplifying the operational procedures.

[0062] The above description is only a preferred embodiment of the present invention, but the present invention should not be limited to the content disclosed in the embodiments and drawings. Therefore, any equivalent or modified embodiments made without departing from the spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A high-concentration, ultrafine anthraquinone cooking aid, characterized in that, By weight, it includes the following raw material components: 10-15 parts sulfonated anthraquinone, 15-25 parts anthraquinone, 2-8 parts sodium dithionite, 1.0-2.0 parts wetting agent, 0.5-2.0 parts dispersant, 0.2-0.8 parts defoamer, 0.5-2.0 parts NaOH, 0.5-1.5 parts xanthan gum, 0.5-1.0 parts ethyl hydroxyethyl cellulose, 0.1-0.3 parts preservative, and 50-65 parts water.

2. The high-concentration ultrafine anthraquinone cooking aid as described in claim 1, characterized in that, By weight, the sulfonated anthraquinone comprises 12 parts, the anthraquinone comprises 18 parts, and the sodium dithionite comprises 5 parts.

3. The high-concentration ultrafine anthraquinone cooking aid as described in claim 1, characterized in that, The wetting agent is octylphenol polyoxyethylene ether, with a weight ratio of 1.3 parts.

4. The high-concentration ultrafine anthraquinone cooking aid as described in claim 1, characterized in that, The dispersant is sodium dodecylbenzenesulfonate, in parts by weight of 0.

6.

5. The high-concentration ultrafine anthraquinone cooking aid as described in claim 1, characterized in that, The defoamer is polyether-modified silicone oil, with a weight ratio of 0.4 parts.

6. The high-concentration ultrafine anthraquinone cooking aid as described in claim 1, characterized in that, The preservative is 2-methylbenzisothiazolinone, in parts by weight of 0.

2.

7. A method for preparing a high-concentration, ultrafine anthraquinone cooking aid, characterized in that... Specifically, the steps include the following: S1. Pre-dispersion and alkalization reaction: Take 10-15 parts of sulfonated anthraquinone and 15-25 parts of anthraquinone according to the formula, dilute with water, and add 0.5-2.0 parts of NaOH and 2-8 parts of sodium dithionite in sequence while stirring. Stir and react at room temperature for 15-30 minutes to convert some anthraquinone into anthraquinone. S2. Emulsification and dispersion: Add 1.0-2.0 parts wetting agent, 0.5-2.0 parts dispersant, 0.2-0.8 parts defoamer and 0.1-0.3 parts preservative to the above system in sequence, and stir thoroughly to form a stable emulsion; S3, Suspension agent compounding: Dissolve 0.5-1.5 parts xanthan gum and 0.5-1.0 parts ethyl hydroxyethyl cellulose separately in water, and then compound them into a suspension agent at an oven-dry weight ratio of 1:1 to 2:

1. S4. Fine grinding: The obtained emulsion is finely ground until the particle size D50 < 2μm and D90 < 10μm. S5. Suspension stability: Add the pre-mixed xanthan gum and ethyl hydroxyethyl cellulose compound suspending agent to the ground material, and stir thoroughly until uniformly dispersed to form a uniform and stable high-concentration suspension.

8. The method for preparing the high-concentration ultrafine anthraquinone cooking aid as described in claim 7, characterized in that, In step S1, the pH of the control system is maintained between 6.0 and 8.0, with no foaming.

9. The method for preparing the high-concentration ultrafine anthraquinone cooking aid as described in claim 7, characterized in that, In step S4, fine grinding is carried out using a sand mill or a ball mill, with zirconium oxide beads as the grinding media.

10. The method for preparing the high-concentration ultrafine anthraquinone cooking aid as described in claim 7, characterized in that, In step S5, the solid content in the high-concentration suspension is controlled to be 30-35%.

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