A wood fiber softening penetrant and its preparation method

Abstract

The present invention relates to the technical field of pulp and paper making, and specifically relates to a softening and penetrating agent for wood fibers and a preparation method thereof. The present invention overcomes the problems of poor penetration effect of the penetrating agent, high power consumption, and poor pulp quality during the preparation process of chemical mechanical pulping. By impregnating the raw materials and then performing defibration, primary pre-impregnation, defibration, adding a substance containing a penetrating agent for secondary pre-impregnation, and then through steps such as primary grinding, primary low-concentration grinding, and secondary low-concentration grinding, high-quality pulp is prepared. By using synthetic penetrating agent one, the power consumption of the pulp is reduced and the tensile index is overall improved; by changing the ratio of penetrating agent one and penetrating agent two, changing the type and proportioning of penetrating agent two, the average power consumption per ton of pulp is reduced; by changing the dosage of the penetrating agent, changing the conditions of the pre-impregnation stage and the defibration conditions, the fineness of the pulp increases, the bulk thickness of the paper made from the pulp decreases, and the mechanical properties are improved; by changing the type and dosage of the defoaming agent, the power consumption is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of pulp and paper making, and specifically to a wood fiber softening penetrant and a preparation method thereof. Background Art

[0002] With the progress of the times and the improvement of living standards, people's demand for the quality of paper is getting higher and higher. The raw materials of paper include wood fibers, plant fibers, and various fibers. These fibers are pulped after pretreatment and further processed to obtain paper. The quality of the pulp is closely related to the pretreatment steps. The main components of wood fibers include cellulose, hemicellulose, lignin, and extractives. The pretreatment is mainly to remove hemicellulose, lignin, etc., so as to improve the quality of the pulp. The commonly used substance in the pretreatment is the penetrant. The quality of the penetrant has a direct positive relationship with the quality of the pulp obtained.

[0003] The penetrant is an auxiliary agent that promotes the rapid wetting of the surface of fibers or fabrics by water, improves the surface tension of the liquid phase, increases fluidity, and penetrates into the interior of the fibers, and promotes the penetration of substances such as sodium hydroxide into the interior of the fibers. The requirements that the penetrant needs to meet are to be resistant to hard water and alkali and have strong permeability. The raw materials for making paper are various fiber raw materials. The fiber raw materials need to be chopped and cooked into pulp first. Due to the different compositions and chemical components of these fiber materials, the penetrant cannot achieve good penetration, the wood chip fibers cannot be well softened, the yield and efficiency of the pulp fibers are low, and the power consumption increases, and the energy saving is poor.

[0004] To overcome the above technical problems, Patent CN115262256B discloses a small molecule fiber penetrant softener and a preparation method thereof. Using substances such as sugar, alcohol, acid, alkali, and modifier as the small molecule fiber penetrant softener, first using glucose containing highly active hemiacetal hydroxyl as the raw material, reacting with ethanol / n-butanol under the action of a catalyst to carry out an acetal reaction, and then compounding the obtained small molecule surfactant with N-methylmorpholine oxide and fast penetrant T to obtain the penetrant softener. The penetrant softener can reduce the surface tension of the impregnating liquid medicine. The small molecule acetal product can penetrate into the interior of the fibers, which is beneficial to the subsequent fibrillation of the fibers into pulp, and at the same time the usage amount of the chemical liquid medicine is also reduced. However, the freeness of the fibers is relatively high, the water filtration performance is poor, and the drug impregnation effect is reduced.

[0005] The literature "Jinglin T, Ziyan H, Yongxiang M, et al. Synthesis and Surface Properties of Polyether‐Based Silicone Surfactants with Different Siloxane Groups[J]. Journal of Surfactants and Detergents, 2019, 22(4): 875-883." discloses polyether-based silicone surfactants containing different siloxane groups. Such surfactants have good penetration and can significantly reduce the surface tension of water, but have poor degradation performance and environmental friendliness.

[0006] Patent CN113174770B discloses a method for pretreating poplar wood fibers by coupling steam explosion with penetrant and phosphoric acid infiltration. The method involves impregnating crushed poplar wood chips into a mixed impregnating solution containing a penetrant and a phosphoric acid solution, mixing evenly and impregnating, then performing explosion and post-treatment to complete the treatment process of the raw materials. The penetrant used is a condensate of ethylene oxide and higher fatty alcohols, which has good penetration effect, simple operation, low cost and high efficiency. The penetrant promotes the significant degradation of hemicellulose in poplar wood fibers, improving the problems of large fiber diameter, large fineness of the pulp, poor mechanical properties of the paper prepared from the pulp and low tensile index.

[0007] In the prior art, there are problems such as high power consumption, high fineness of the pulp, and poor mechanical properties of the paper made from the pulp when using penetrants in the pulping process of wood materials. In addition, due to low temperature and low alkali consumption in the production process of chemimechanical pulping, the raw materials cannot be fully softened, resulting in high power consumption, serious damage to fibers under stress, and low pulp quality. The actual penetration effect of similar products on the market for wood materials and non-wood materials is not ideal, and the pulp quality is low.

[0008] Therefore, a wood fiber softening penetrant and its preparation method are proposed. Summary of the Invention

[0009] The object of the present invention is to provide a wood fiber softening penetrant and its preparation method. By using alkyl glycoside as the main raw material, penetrant one is synthesized. The penetrant prepared from penetrant one is applied to the pulping of eucalyptus, poplar and Broussonetia papyrifera. The power consumption of the pulp is reduced, the fiber humidity is increased, and the overall tensile index is improved. By changing the ratio of penetrant one and penetrant two, changing the type and ratio of penetrant two, the average power consumption per ton of pulp is reduced. By changing the dosage of the penetrant, changing the temperature, time and defibration conditions in the pre-impregnation stage, the fineness of the pulp is increased, the bulk thickness of the paper made from the pulp is reduced, and the mechanical properties are improved. By changing the type, dosage and ratio of the defoamer, the power consumption is reduced.

[0010] To achieve the above object, the present invention provides the following technical solutions:

[0011] On the one hand, the present invention provides a preparation method of a wood fiber softening penetrant, comprising the following steps:

[0012] Heat up the maleic anhydride solution and then carry out a reflux reaction, and cool down to obtain an aqueous solution of maleic acid; adjust the pH of the aqueous solution of maleic acid to 3 using phosphoric acid, and then add 10.0 - 12.0 parts of polyethylene glycol thereto to obtain a mixed solution; heat up the mixed solution and carry out a reflux reaction for 1 h to obtain a solution of polyethylene glycol maleate; the average molecular weight of the polyethylene glycol is 200 - 1000;

[0013] Dissolve alkyl polyglycoside in deionized water to obtain an alkyl polyglycoside solution; add p-toluenesulfonic acid and the solution of polyethylene glycol maleate to the alkyl polyglycoside solution to obtain a penetrant precursor solution; add 3-(2,3-epoxypropoxy)propyltrimethoxysilanol and concentrated sulfuric acid to the penetrant precursor solution, continue the reaction, then carry out suction filtration and vacuum drying to obtain penetrant one; the degree of polymerization n of the alkyl polyglycoside is 1.1 - 3.0;

[0014] After mixing penetrant one and penetrant two in a volume ratio of 1 - 9:3 - 13 and stirring and mixing at 60 °C, a light yellow viscous liquid is obtained; cool down to room temperature to prepare the Kant KDHG-S518 penetrant, that is, the wood fiber softening penetrant; the components of penetrant two are any three of sodium dioctyl sulfosuccinate, fatty alcohol polyoxyethylene ether, isooctyl alcohol polyoxyethylene ether phosphate, linear alkylbenzene sulfonate, fatty alcohol polyoxyalkyl ether, and alkyl trimethyl ammonium salt; the volume ratio of the components of penetrant two is 1 - 7:1 - 5:2 - 8.

[0015] Alkyl polyglycoside non-ionic surfactant has the properties of both ionic and anionic surfactants, has good foaming property (rich and fine foam), is resistant to strong alkali and electrolyte, has good surface activity, and has good degradability compared with conventional high molecular surfactants. It is a "green" functional surfactant. Through its surface modification, polyethylene glycol and hydrolyzed epoxy silane are introduced, further improving its penetration into wood raw materials and enhancing the good absorption of wood materials to drugs.

[0016] The hydrophilicity of polyethylene glycol and alkyl polyglycoside and the lipophilicity of 3-(2,3-epoxypropoxy)propyltrimethoxysilanol constitute the main body of penetrant one. The effective combination of amphoteric functional groups, and at the same time controlling the molecular weight of polyethylene glycol and the degree of polymerization of alkyl polyglycoside, make the molecular weight of penetrant one within a reasonable range. If the molecular weight is small, the penetration is incomplete; if the molecular weight is large, the penetration resistance increases. Within an appropriate range, it enables all-round three-dimensional wetting and promotes the penetration process.

[0017] Preferably, the preparation method of 3-(2,3-epoxypropoxy)propyltrimethoxysilanol is as follows: Mix deionized water, methanol, and 29.7 parts of glycerol to obtain a mixed solvent; add 3-(2,3-epoxypropoxy)propyltrimethoxysilane to the mixed solvent, adjust the pH of the system to 4.0 with phosphoric acid, then stir at room temperature until the system becomes transparent after 30 minutes, and then dry the system to remove water and organic solvents to obtain 3-(2,3-epoxypropoxy)propyltrimethoxysilanol.

[0018] Preferably, the degree of polymerization n of the alkyl glycoside is 1.4 - 2.4, and the polyethylene glycol is one of PEG200, PEG300, PEG400, PEG600, and PEG1000.

[0019] Preferably, the degree of polymerization of the fatty alcohol polyoxyethylene ether is 3 or 9.

[0020] On the other hand, the present invention provides a wood fiber softening penetrant, which is the Kant KDHG-S518 penetrant; the wood fiber softening penetrant includes penetrant one and penetrant two; the volume ratio of penetrant one to penetrant two is 1 - 9:3 - 13; the components of penetrant two are any three of sodium dioctyl sulfosuccinate, fatty alcohol polyoxyethylene ether, isooctyl alcohol polyoxyethylene ether phosphate, linear alkylbenzene sulfonate, fatty alcohol polyoxyalkyl ether, and alkyltrimethyl ammonium salt; the volume ratio of the components of penetrant two is 1 - 7:1 - 5:2 - 8.

[0021] Preferably, the application of the wood fiber softening penetrant in chemical mechanical pulping; the steps of the chemical mechanical pulping are as follows: Immerse the raw materials in hot water; perform one-stage extrusion and defibration after the immersion; perform one-stage pre-impregnation after the one-stage extrusion and defibration; perform two-stage extrusion and defibration after the one-stage pre-impregnation; perform two-stage pre-impregnation after the two-stage extrusion and defibration; obtain pulp after one-stage grinding, two-stage grinding, defoaming, screening, and beating steps; the two-stage grinding includes one-stage low-concentration grinding and two-stage low-concentration grinding; the screw compression ratio of the one-stage extrusion and defibration to the two-stage extrusion and defibration is 2 - 6:1; the material-liquid ratio of the raw materials to the hot water for immersion is 1:6.5; the temperature of the one-stage pre-impregnation is 80 - 90°C, and the time is 60 - 90 minutes; calculated as a percentage of 1 ton of pulp, the dosage of the penetrant in the two-stage pre-impregnation is 0.50% - 1.02%, the dosage of the defoamer is 0.10% - 0.32%, the dosage of sodium hydroxide is 1.5%, the dosage of sodium silicate is 1.2%, the dosage of hydrogen peroxide is 1.6%, the dosage of DTPA chelating agent is 0.005%, the temperature is 55 - 70°C, and the time is 30 - 40 minutes.

[0022] Preferably, the raw material is any one, two or three of eucalyptus, poplar, Broussonetia papyrifera, birch, acacia, rice straw, sorghum stalk, and corn stalk.

[0023] Preferably, the defoamer is obtained by mixing an alcohol defoamer, a phosphoric acid defoamer, and a silicone defoamer in a mass ratio of 1-4:1-3:1.

[0024] Preferably, the alcohol defoamer is any one of a fatty alcohol defoamer, a higher alcohol defoamer, ethanol, and n-propanol; the phosphoric acid defoamer is any one of tributyl phosphate and triisobutyl phosphate; the silicone defoamer is any one of a paper pulp black liquor defoamer and a general-purpose silicone defoamer.

[0025] Preferably, the wood fiber softening penetrant is prepared by the preparation method of any one of the above; using the wood fiber softening penetrant, the average power consumption per ton of pulp with eucalyptus as the raw material is 920-929 KWh / admt, the average wet weight of the fiber is 1.40-1.51, and the average tensile index is 18.6-21.5 N·m / g; the average power consumption per ton of pulp with poplar as the raw material is 912-920 KWh / admt, the average wet weight of the fiber is 1.28-1.43, and the average tensile index is 19.3-22.4 N·m / g; the average power consumption per ton of pulp with Broussonetia papyrifera as the raw material is 908-917 KWh / admt, the average wet weight of the fiber is 1.30-1.48, and the average tensile index is 19.0-21.7 N·m / g; the average power consumption per ton of pulp with birch as the raw material is 1031.2-1038.5 KWh / admt; the proportion of fibers with a high concentration of pulp greater than 50 mesh as the raw materials of rice straw, sorghum stalk, and corn stalk is 24.7%-28.5%, the Canadian freeness is 782-794 mL, and the whiteness is 25.99%-26.50%; the proportion of the second-stage low-concentration ground pulp with a particle size greater than 50 mesh as the raw materials of the rice straw, the sorghum stalk, and the corn stalk is 4.26%-4.87%, the bulk thickness of the paper is 2.20-2.58 cm 3 / g, the tensile index of the paper is 22.6-27.1 N·m / g, the outlet power of the first-stage low-concentration grinder is 2198-2205 KW, and the outlet power of the second-stage low-concentration grinder is 1128-1153 KW; the Canadian freeness of the pulp with eucalyptus and acacia as the raw materials is 402-418 mL, and the power consumption is 673-690 KW·h.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] 1. By using alkyl polyglycoside as the main raw material and grafting and synthesizing a grafted penetrant on its surface, it has good penetration effects on eucalyptus, poplar, and Broussonetia papyrifera. By reacting maleic anhydride, polyethylene glycol, and 3-(2,3-epoxypropoxy)propyltrimethoxysilanol with alkyl polyglycoside to polymerize, controlling the molecular weight and dosage of polyethylene glycol, and at the same time controlling the molecular polymerization degree of alkyl polyglycoside, the synthesized penetrant has good penetration effects on various woody materials during the chemi-mechanical pulping process. The power consumption for chemi-mechanical pulping is reduced. When the beating degree is certain, the wet weight of the pulp fibers is large, the tensile index is high, and the strength of the pulp is high.

[0028] 2. The present invention prepares an alkyl polyglycoside non-ionic polymer penetrant. By using it in a binary compounding with another penetrant, the penetration effect of the penetrant is improved, making plant fibers easy to be softened. The mechanical resistance generated by harder fibers during the beating process is reduced, and more current supply is required to overcome the corresponding resistance. By controlling the volume ratio between penetrant one and penetrant two, the type of penetrant two and the volume ratio of each component of penetrant two, the power consumption is reduced while ensuring the stability of the pulp quality, achieving the effect of energy conservation.

[0029] 3. The present invention controls the screw compression ratio, the dosage of the penetrant, and the temperature and impregnation time in the first and second pre-impregnation stages during the extrusion and defibration process, so that the proportion of fibers larger than 50 mesh after high-concentration residence is reduced, and the fiber diameter decreases, which is conducive to the subsequent beating process, improving the fineness of the pulp, but having no obvious influence on the freeness and whiteness of the pulp.

[0030] 4. The present invention pressurizes and defibrates the woody materials before pre-impregnation, controls the operating conditions of the defibrating instrument, and reasonably controls the dosage of the penetrant during the two-stage pre-impregnation process, and selects appropriate pre-impregnation temperature and pre-impregnation time. As a result, the fineness of the pulp from the two-stage low-concentration grinding decreases, the bulk density decreases, and the tensile index increases. In addition, on the premise of ensuring the pulp quality, the outlet power of the two-stage low-concentration grinding can be appropriately reduced.

[0031] 5. The present invention controls the addition ratio of the defoamer in the pre-impregnation section, controls the types and ratios of each component in the defoamer, and avoids generating large and small bubbles during the addition of the penetrant and other substances and during the stirring process, so that the penetration process proceeds stably. The freeness of the prepared pulp decreases, the freeness of the pulp is moderate, and the water filtration performance is good. In addition, the power consumption is reduced and the process is energy-saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a graph showing the bulk density and tensile index results of the two-stage pulp for Examples 25 - 32 of the present invention;

[0033] Figure 2This is the power consumption result graph of Examples 45 - 57 and Comparative Examples 6 - 9 of the present invention;

[0034] Figure 3 This is the process flow chart of the pulping process of the present invention. Detailed implementation manners

[0035] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0036] Please refer to Figures 1 to 3 , the present invention provides a wood fiber softening penetrant and a preparation method thereof, and the technical solutions are as follows:

[0037] The substance information involved in the present invention is as follows:

[0038] 3-(2,3-epoxypropoxy)propyltrimethoxysilane CAS: 2530-83-8; p-toluenesulfonic acid CAS: 104-15-4; sodium dioctyl sulfosuccinate CAS: 1639-66-3; isooctyl alcohol polyoxyethylene ether phosphate CAS: 68439-39-4; linear alkylbenzene sulfonate CAS: 25155-30-0; alkyltrimethylammonium salt CAS: 85409-24-1; tributyl phosphate CAS: 126-73-8; triisobutyl phosphate CAS: 126-71-6; fatty alcohol polyoxyethylene ether (N = 3) (AEO-3), fatty alcohol polyoxyalkyl ether, fatty alcohol polyoxyethylene ether (N = 9) (AEO-9) are all purchased from BASF Chemical Co., Ltd.; high-carbon alcohol defoamer, fatty alcohol defoamer, and pulp black liquor defoamer are all purchased from Foshan Nanhai Datian Chemical Co., Ltd.; general-purpose silicone defoamer is purchased from Hubei Chengfeng Chemical Co., Ltd.; Example 1

[0039] The preparation method of penetrant 1 is as follows:

[0040] Add 9.9 parts of maleic anhydride and 100 parts of deionized water into a round-bottom flask, and add 0.1 part of potassium hydroxide thereto, and mix evenly to obtain a maleic anhydride solution; heat up to 80 °C, reflux for 100 min, and cool down to obtain an aqueous solution of maleic acid; adjust the pH of the aqueous solution of maleic acid to 3 with phosphoric acid, and then add polyethylene glycol (average molecular weight 200) thereto to obtain a mixed solution; heat up the mixed solution to 115 °C, and continue to reflux for 1 h to obtain a solution of maleic acid polyethylene glycol ester.

[0041] Mix 31.0 parts of deionized water, 15.8 parts of methanol, and 29.7 parts of glycerol to obtain a mixed solvent; add 23.6 parts of 3-(2,3-epoxypropoxy)propyltrimethoxysilane to the mixed solvent, adjust the pH of the system to 4.0 using phosphoric acid, then stir at room temperature until the system becomes transparent after 30 min, and then dry the system to remove water and organic solvents to obtain 3-(2,3-epoxypropoxy)propyltrimethoxysilanol.

[0042] Dissolve 10 parts of alkyl polyglycoside (degree of polymerization n = 1.4) in 100 parts of deionized water to obtain an alkyl polyglycoside solution; transfer the alkyl polyglycoside solution to a high-temperature and high-pressure reactor, and add 1.2 parts of p-toluenesulfonic acid and a polyethylene glycol maleate solution, and react at 110 °C for 1.5 h to obtain a penetrant-precursor solution; add 19.5 parts of 3-(2,3-epoxypropoxy)propyltrimethoxysilanol and 1.5 parts of concentrated sulfuric acid to the penetrant-precursor solution, continue to raise the temperature to 120 °C, and stir and react for 5 h to obtain a penetrant-intermediate solution; cool the penetrant-intermediate solution to room temperature, then filter by suction and dry under vacuum to obtain penetrant one. All reactions are carried out under nitrogen protection.

[0043] The penetrant is composed of penetrant one and penetrant two mixed in a volume ratio of 3:7; penetrant two is prepared from sodium dioctyl sulfosuccinate, AEO-3, and polyoxyethylene isooctyl ether phosphate in a volume ratio of 1:1:2. After penetrant one and penetrant two are mixed, stir and mix at 60 °C to obtain a light yellow viscous liquid; cool to room temperature to prepare the Kant KDHG-S518 penetrant, that is, the wood fiber softening penetrant.

[0044] The overall process flow during the use of the penetrant is as follows, specifically as Figure 3 shown: Immerse the raw materials in hot water (material-liquid ratio 1:6.5), then carry out primary extrusion and defibration (screw compression ratio 4.5:1), primary pre-impregnation (10 Kg of sodium hydroxide per ton of pulp, 12 Kg of sodium silicate per ton of pulp, 13 Kg of hydrogen peroxide per ton of pulp, 0.5 Kg of DTPA per ton of pulp, 80 °C, 90 min), secondary extrusion and defibration (screw compression ratio 4.5:1), secondary pre-impregnation (6.0 Kg of penetrant per ton of pulp, 1.2 Kg of defoamer per ton of pulp, 15 Kg of sodium hydroxide per ton of pulp, 12 Kg of sodium silicate per ton of pulp, 16 Kg of hydrogen peroxide per ton of pulp, chelating agent DTPA 0.5 Kg of per ton of pulp, 70 °C, 45 min), primary grinding, secondary grinding (primary low-concentration grinding, secondary low-concentration grinding), dewatering, screening, beating, sheet forming, and performance testing.

[0045] Examples 2-12

[0046] Comparative Examples 1-3

[0047] Different from Example 1, the detailed information of the preparation process of the example is shown in Table 1.

[0048] Table 1 Preparation method of penetrant 1

[0049] Example 13

[0050] The penetrants prepared in Examples 1-12 and Comparative Examples 1-3 were applied to the pilot test of the chemimechanical pulping process. The test time was from 16:00 on August 26, 2022 to 23:00 on August 28, 2022. The raw materials were tested using 1000 kg of eucalyptus, 1000 kg of poplar, and 1000 kg of Broussonetia papyrifera respectively. The on-site production status was 700 tons per day, and the penetrant was continuously added by using a metering pump. The power consumption, wet fiber weight (when the beating degree was 25), and tensile index during the test process were recorded. The determination of the tensile index was carried out according to GB / T 12914-2018 "Paper and paperboard - Determination of tensile strength - Constant rate of elongation method (20 mm / min)". The test results are shown in Table 2.

[0051] Table 2 Test results of penetrants in Examples 1-12 and Comparative Examples 1-3

[0052]

[0053] The penetrant prepared by the present invention is used in the chemimechanical pulping process, such as Figure 3As shown in the figure. After applying the penetrant, the average power consumption per ton of pulp with eucalyptus as the raw material is 920 - 929 KWh / admt, the average wet fiber weight is 1.40 - 1.51, and the average tensile index is 18.6 - 21.5 N·m / g; the average power consumption per ton of pulp with poplar as the raw material is 912 - 920 KWh / admt, the average wet fiber weight is 1.28 - 1.43, and the average tensile index is 19.3 - 22.4 N·m / g; the average power consumption per ton of pulp with Broussonetia papyrifera as the raw material is 908 - 917 KWh / admt, the average wet fiber weight is 1.30 - 1.48, and the average tensile index is 19.0 - 21.7 N·m / g. Before adding the penetrant and two days after adding it, the average power consumption per ton of pulp of the three wood materials increased compared with the examples, while the average wet fiber weight and the average tensile index decreased. The results of Examples 1 - 3 show that by changing the dosage of polyethylene glycol, the average power consumption per ton of pulp, the average wet fiber weight, and the average tensile index changed. The results of Examples 2, 4 - 7 show that with the increase in the molecular weight of polyethylene glycol, the average power consumption per ton of pulp changed insignificantly, while the average wet fiber weight and the average tensile index showed a trend of increasing first and then decreasing. The results of Examples 6, 8 - 12 show that when the degree of polymerization of alkyl polyglycoside is controlled within the range of 1.4 - 2.4, the power consumption and the strength of the pulp change. In Comparative Example 1, the molecular weight of polyethylene glycol was too large, resulting in no obvious change in the average power consumption per ton of pulp compared with the groups two days before and two days after adding the penetrant, and the increase in the average wet fiber weight and the average tensile index was not significant. In Comparative Examples 2 and 3, whether the degree of polymerization of alkyl polyglycoside was too high or too low, the improvement of the pulp strength was not obvious. In summary, compared with the groups two days before and two days after adding the penetrant, the power consumption decreased and the pulp strength increased in the examples and comparative examples. The average tensile index of poplar is the highest among eucalyptus and Broussonetia papyrifera, and the average wet fiber weight of eucalyptus is the highest among poplar and Broussonetia papyrifera.

[0054] Examples 14 - 23

[0055] Different from Example 9, the following preparation conditions changed, as shown in Table 3 specifically.

[0056] Table 3 Composition and dosage ratio of penetrant one and penetrant two

[0057]

[0058] Comparative Example 4

[0059] Different from Example 14, only penetrant one was added as the penetrant.

[0060] Comparative Example 5

[0061] Different from Example 14, the penetrant was added in the first-stage pre-impregnation stage. Example 24

[0062] The penetrants obtained in Example 9, Examples 14 - 23, and Comparative Examples 4 and 5 were used in the preparation of chemi-mechanical pulping of birch. The pilot process was as follows: At 10:00 on June 3, the penetrant of Kurita 1203 was used online (dosage: 0.8 kg / t pulp), and on June 8 at 14:00, the penetrants of the examples and comparative examples were switched respectively. During the experiment, the pulp quality remained stable. Only the process parameters were adjusted, and real-time records were made for the equipment with large energy consumption, including the 1# main grinder, 2# main grinder, 1# low-concentration grinder, 2# low-concentration grinder, and slag pulp grinder.

[0063] The power consumption results are shown in Table 4, and the specific recorded data of Example 14 are shown in Table 5.

[0064] Table 4 Power consumption results of examples and comparative examples

[0065]

[0066] Table 5 Specific test data of Example 14

[0067]

[0068]

[0069] During the preparation process of chemi-mechanical pulping, by using the penetrants prepared in the examples and comparative examples, the average power consumption per ton of pulp is in the range of 1031.2 - 1038.5 KWh / admt. The results of Examples 14 - 16 show that by changing the proportions of the components in penetrant two, the power consumption gradually increases. Sodium dioctyl sulfosuccinate is mainly an anionic surfactant. The sulfosuccinic acid therein can act on the moisture on the fiber surface, and the ester can enter the interior of the fiber, thereby reducing the surface tension, promoting the penetration and dispersion of substances such as sodium hydroxide and hydrogen peroxide, promoting the decomposition of non-wood fiber substances such as sugars and lignin in wood materials, and promoting the fibrillation of wood fibers. AEO-3 is a condensate of fatty alcohol and ethylene oxide, and isooctyl alcohol polyoxyethylene ether phosphate. Both are non-ionic surfactants and act synergistically with penetrant one to improve the penetration ability for fibers. The results of Examples 14, 17 - 19 show that by increasing the proportion of penetrant one, the average power consumption per ton of pulp first decreases and then increases, indicating that the volume ratio of penetrant one and penetrant two needs to be controlled within a reasonable range. The results of Examples 14, 20 show that using sodium dioctyl sulfosuccinate in penetrant two results in lower power consumption. This may be because compared with linear alkylbenzene sulfonate, its special structural composition makes its permeability stronger. The results of Examples 14, 21 - 23 show that when replacing isooctyl alcohol polyoxyethylene ether phosphate with alkyltrimethylammonium salt, the power consumption increases. Alkyltrimethylammonium salt is a cationic surfactant, and the ammonium salt adheres to the surface of wood materials, hindering the progress of the wetting process, thereby reducing the penetration effect. Combining the data in Table 5, it can be seen that using Kurita 1203 penetrant in the first half and then using the penetrant prepared by the present invention in the second half significantly reduces the power consumption. Comparative Example 4 only adds penetrant one as the penetrant, and the power consumption increases compared with the examples. In Comparative Example 5, the penetrant is added in the first-stage pre-impregnation section, and the addition time is too early, resulting in a decrease in the penetration effect and an increase in power consumption.

[0070] Examples 25 - 42

[0071] Comparative Example 6

[0072] Different from Example 21, the following preparation conditions are changed, as shown in Table 6 specifically.

[0073] Table 6 Condition changes during the preparation process

[0074] Example 43

[0075] According to the methods of Examples 25 - 42 and Comparative Example 6, the freeness, whiteness and fibers of the chemi-mechanical pulp prepared from the raw materials (15% rice straw + 45% sorghum stalk + 40% corn stalk) are classified. The penetrant is added continuously at a flow rate of 170 mL / min, and the quality of the pulp in the high-concentration refining section is tested.

[0076] The Canadian standard freeness tester is used to measure the drainage performance of the pulp suspension, so as to evaluate the freeness of the pulp. The pulp suspension is diluted to a concentration of 0.3%, and the temperature is 20.5 °C. The whiteness is measured in accordance with GB / T 7974-2002 "Paper, board and pulp - Determination of brightness (whiteness) (diffuse / vertical method)", and the test is carried out using a WS-SD chromaticity whiteness meter manufactured by Wenzhou Instrument and Meter Co., Ltd. The test results are shown in Table 7. The specific results of the test processes of Example 32 and Comparative Example 6 are shown in Tables 8 and 9.

[0077] Table 7 Test results of fiber ratio, freeness and whiteness

[0078]

[0079] In the example, the proportion of fibers with a mesh size greater than 50 at the outlet of the high - consistency refining section (i.e., the high - consistency pulp after the first - stage refining) is 24.7% - 28.5%, the Canadian freeness is 782 - 794 mL, and the whiteness is 25.99% - 26.50%. The results show that by controlling the dosage of the penetrant, the compression ratio of the first - stage extrusion and defibration screw, the temperature and time of the first - stage pre - impregnation, and the temperature and time of the second - stage pre - impregnation, there is no obvious effect on the freeness and whiteness of the pulp, but the fineness of the formed pulp is improved. The possible reason is that the whiteness of the pulp is related to the dosage of hydrogen peroxide, and the freeness of the pulp is related to the wood raw materials used and the instrument parameters of the beater, so the performance does not change significantly. However, the proportion of fibers with a mesh size greater than 50 decreases. In Examples 25 - 32, as the dosage of the penetrant gradually increases, the proportion of fibers with a mesh size greater than 50 gradually decreases. The increase in the dosage of the penetrant increases the softness of the wood pulp, making it easier for sodium hydroxide and other substances to penetrate into it, and it is more likely to break under the same mechanical force, thus reducing the fiber diameter and increasing the fineness. In Comparative Example 6, no penetrant is added, the penetration effect decreases, and the hardness of the wood material increases, so the fiber diameter increases after beating. The results of Examples 32 - 36 show that by changing the compression ratio of the first - stage extrusion and defibration screw, when the ratio of Example 34 is 6:1, the fineness is the smallest. The results of Examples 34, 37 - 42 show that by controlling the pre - impregnation time and temperature of the first - stage and the second - stage, the permeability of the penetrant and other components is enhanced, thereby reducing the fineness of the pulp. Combining the results in Table 8, it can be seen that the freeness and whiteness of the pulp are in an overall dynamic change process. After being treated with the penetrant and conditions of Example 32 of the present invention, the freeness decreases and the whiteness increases, but the change is not significant. The results in Table 9 show that the overall fineness decreases under the conditions of Example 32.

[0080] Table 8 Specific results of freeness and whiteness of Example 32 and Comparative Example 6

[0081]

[0082] Table 9 Results of fiber classification and proportion of >50 mesh in Example 32 and Comparative Example 6

[0083] Example 44

[0084] The raw materials (15% rice straw + 45% sorghum straw + 40% corn straw) were processed according to the methods of Examples 25 - 42 and Comparative Example 6, and the chemi-mechanical pulps prepared were tested for the power consumption, bulk, strength, and proportion of fibers of fixed size in the first-stage and second-stage grinding. The penetrant was added continuously at a flow rate of 170 mL / min. The pulp was made into paper, and the thickness and strength were determined according to the method of GB / T 24323―2009 "Pulp - Laboratory Sheet - Determination of Physical Properties". The test results are shown in Table 10. The bulk and tensile index results of the second-stage pulp in Examples 25 - 32 are as Figure 1 shown. The basic situations such as power consumption during the test of Example 32 and Comparative Example 6 are shown in Table 11, and the fiber diameter information at the outlet of the second-stage low-concentration grinder is shown in Table 12.

[0085] Table 10 Test Results of Pulp Physical Properties in Examples 25 - 42 and Comparative Example 6

[0086]

[0087] The proportion of >50 mesh in the second-stage low-concentration ground pulp of the present invention is 4.26% - 4.87%, the bulk of the paper is 2.20 - 2.58 cm 3 / g, the tensile index of the paper is 22.6 - 27.1 N·m / g, the power at the outlet of the first-stage low-concentration grinder is 2198 - 2205 KW, and the power at the outlet of the second-stage low-concentration grinder is 1128 - 1153 KW. In Example 44, the proportion of >50 mesh in the second-stage ground pulp is much lower than that of the >50 mesh fibers at the outlet of the high-concentration grinder in Example 43. As the chemi-mechanical pulp preparation process progresses, the fineness of the pulp gradually decreases. In Example 43, compared with the group in Comparative Example 6 without adding penetrant, the proportion of >50 mesh in the second-stage ground pulp decreases significantly. The results of the bulk of the second-stage pulp in Table 10 show that as the proportion of >50 mesh in the second-stage ground pulp decreases, the bulk generally shows a decreasing trend, while the tensile index of the second-stage pulp increases instead. When the pulp is made into paper, according to the Page theory, the paper sheet is a network structure randomly composed of fibers. Fibers with small sizes combine more times in the same area and can fill the gaps between larger fibers, making the structure of the paper more compact and the strength greater. Table 12 details the specific changes in the pulp fineness of Comparative Example 6 and Example 32. Therefore, the bulk decreases, the tensile index increases, and the mechanical properties of the paper prepared from the pulp are improved. Combining Figure 1The results show that as the dosage of the penetrant increases, the bulk decreases and the tensile index increases. The results of Examples 25-42 in Table 10 compared with the control group of Example 6 without penetrant show that the power at the outlet of the first-stage low-concentration refiner does not change significantly, but the power at the outlet of the second-stage low-concentration refiner decreases compared with the control group, and the decrease value is 14-39 KW. The specific data during the application of Example 32 are shown in detail in Table 11. By adding the penetrant according to the dosage of the present invention and controlling the process treatment conditions, the fineness of the pulp increases, the power consumption decreases, and at the same time, the mechanical strength of the paper made from the pulp is improved.

[0088] Table 11 Power consumption information during the tests of Example 32 and Comparative Example 6

[0089]

[0090] Table 12 Fiber diameter information at the outlet of the second-stage low-concentration refiner of Example 32 and Comparative Example 6

[0091]

[0092] Examples 45-57

[0093] Comparative Examples 7-9

[0094] The defoamer is obtained by mixing three types of substances in a fixed mass ratio. Different from Example 34, the types and dosages of the defoamer change, as shown in Table 13. The three types of substances in Table 13 are alcohol defoamers, phosphoric acid defoamers, and silicone defoamers in sequence.

[0095] Table 13 Changes in the types and dosages of the defoamer

[0096]

[0097] Example 58

[0098] The defoamers prepared in Examples 45-57 and Comparative Examples 6-9 are used in high-bulk chemimechanical pulping, where the raw materials used are 80% eucalyptus and 20% acacia, the production capacity is 1360 tons per day, the penetrant is continuously added through a metering pump, and the test time is from 08:40 on September 10, 2024 to 08:40 on September 12, 2024. The test results of the freeness and power consumption are shown in Table 14. The changes in the freeness and power consumption during the production process of Example 45 are shown in Table 15.

[0099] Table 14 Changes in the freeness and power consumption of Examples 45-57 and Comparative Examples 7-9

[0100]

[0101] The results in Table 14 show that the Canadian freeness of the slurry prepared by the present invention is 402 - 418 mL, and the power consumption is 673 - 690 KW·h. The results of Examples 45 - 50 show that as the dosage of the defoamer increases, the freeness shows a trend of first increasing and then decreasing. When the dosage of the defoamer in Example 50 is the highest, the freeness is the lowest, and the power consumption shows a trend of decreasing, increasing, and then decreasing. In Example 45, when the dosage of the defoamer is the least, the freeness and power consumption are moderate. The results of Examples 45, 51 - 53 show that by using a higher alcohol defoamer as the type of alcohol defoamer, as shown in Example 51, the power consumption is the lowest. The higher alcohol defoamer has good compatibility with the penetrant, which promotes the function of the penetrant. In Example 54, triisobutyl phosphate is used as the phosphate defoamer, and there is little difference from using tributyl phosphate. The results of Examples 51 and 55 show that the effect of using the pulp black liquor defoamer is better than that of the general-purpose silicone defoamer. The results of Examples 51, 56, and 57 show that when the ratio of the three types of substances in Example 56 is 4:3:3, the power consumption is the lowest, which is 6750 KW·h. Comparing the results of Comparative Examples 6 - 8 with those of Example 45, in the comparative examples, only one type of defoamer is used, and the power consumption and freeness are relatively high. However, the results of Examples 45 - 57 and Comparative Examples 7 - 9 are better than those of Comparative Example 6 without adding the penetrant. The results in Table 15 show that the freeness and power consumption during the production process of Example 45 are lower than those of Comparative Example 6 without adding the penetrant.

[0102] Table 15 Changes in freeness and power consumption during the production process of Example 45

[0103]

[0104] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A preparation method of a wood fiber softening penetrant, characterized in that: It includes the following steps: Heat up the maleic anhydride solution and carry out a reflux reaction, then cool down to obtain an aqueous solution of maleic acid; adjust the pH of the aqueous solution of maleic acid to 3 with phosphoric acid, and then add 10.0 - 12.0 parts of polyethylene glycol to obtain a mixed solution; heat up the mixed solution and carry out a reflux reaction for 1 h to obtain a solution of polyethylene glycol maleate; the average molecular weight of the polyethylene glycol is 200 - 1000; Dissolve alkyl polyglycoside in deionized water to obtain an alkyl polyglycoside solution; add p-toluenesulfonic acid and the solution of polyethylene glycol maleate to the alkyl polyglycoside solution to obtain a precursor solution of penetrant I; add 3-(2,3-epoxypropoxy)propyltrimethoxysilanol and concentrated sulfuric acid to the precursor solution of penetrant I, continue the reaction, then carry out suction filtration and vacuum drying to obtain penetrant I; the degree of polymerization n of the alkyl polyglycoside is 1.1 - 3.0; Mix penetrant I and penetrant II in a volume ratio of 1 - 9:3 - 13, and stir and mix at 60 °C to obtain a light yellow viscous liquid; cool down to room temperature to prepare the wood fiber softening penetrant; the components of penetrant II are any three of sodium dioctyl sulfosuccinate, isooctyl alcohol polyoxyethylene ether phosphate, linear alkylbenzene sulfonate, fatty alcohol polyoxyalkylene ether, and alkyl trimethyl ammonium salt; the volume ratio of the components of penetrant II is 1 - 7:1 - 5:2 - 8.

2. The preparation method of a wood fiber softening and penetrating agent according to claim 1, characterized in that: The preparation method of 3-(2,3-epoxypropoxy)propyltrimethoxysilanol is as follows: mix the deionized water, methanol, and 29.7 parts of glycerol to obtain a mixed solvent; add 3-(2,3-epoxypropoxy)propyltrimethoxysilane to the mixed solvent, adjust the pH of the system to 4.0 with phosphoric acid, then stir at room temperature until the system becomes transparent after 30 min, and then dry the system to remove water and organic solvents to obtain 3-(2,3-epoxypropoxy)propyltrimethoxysilanol.

3. The preparation method of a wood fiber softening penetrant according to claim 1, characterized in that: The degree of polymerization n of the alkyl polyglycoside is 1.4 - 2.4; the polyethylene glycol is one of PEG200, PEG300, PEG400, PEG600, and PEG1000.

4. A wood fiber softening and penetrating agent, characterized in that: The wood fiber softening penetrant is prepared by the preparation method according to any one of claims 1 - 3; the wood fiber softening penetrant is Kant KDHG-S518 penetrant; the wood fiber softening penetrant includes penetrant I and penetrant II; the volume ratio of penetrant I and penetrant II is 1 - 9:3 - 13; the components of penetrant II are any three of sodium dioctyl sulfosuccinate, isooctyl alcohol polyoxyethylene ether phosphate, linear alkylbenzene sulfonate, fatty alcohol polyoxyalkylene ether, and alkyl trimethyl ammonium salt; the volume ratio of the components of penetrant II is 1 - 7:1 - 5:2 - 8.

5. The wood fiber softening and penetrating agent according to claim 4, characterized in that: The application of the wood fiber softening penetrant in chemi-mechanical pulping; the steps of the chemi-mechanical pulping are as follows: impregnate the raw materials with hot water; carry out one-stage extrusion and defibration after the impregnation; carry out one-stage pre-impregnation after the one-stage extrusion and defibration; carry out two-stage extrusion and defibration after the one-stage pre-impregnation; After the two-stage extrusion and defibration, two-stage pre-impregnation is carried out; after the two-stage pre-impregnation, pulp is obtained through steps of first-stage beating, second-stage beating, defoaming, screening, and refining; the second-stage beating includes first-stage low-concentration beating and second-stage low-concentration beating; the screw compression ratios of the first-stage extrusion and defibration and the second-stage extrusion and defibration are 2-6:1; the material-liquid ratio of the raw material and the hot water for impregnation is 1:6.5; the temperature of the first-stage pre-impregnation is 80-90°C and the time is 60-90 min; calculated as a percentage of 1 ton of pulp, the dosage of the wood fiber softening and penetrating agent in the second-stage pre-impregnation is 0.50%-1.02%, the dosage of the defoaming agent is 0.10%-0.32%, the dosage of sodium hydroxide is 1.5%, the dosage of sodium silicate is 1.2%, the dosage of hydrogen peroxide is 1.6%, the dosage of DTPA chelating agent is 0.005%, the temperature is 55-70°C, and the time is 30-40 min.

6. The wood fiber softening and penetrating agent according to claim 5, wherein: The raw material is any one, two or three of eucalyptus, poplar, Broussonetia papyrifera, birch, acacia, rice straw, sorghum stalk, and corn stalk.

7. The wood fiber softening and penetrating agent according to claim 5, characterized in that: The defoaming agent is obtained by mixing an alcohol defoaming agent, a phosphoric acid defoaming agent, and an organosilicon defoaming agent according to a mass ratio of 1-4:1-3:

1.

8. The wood fiber softening penetrant according to claim 7, characterized in that: The alcohol defoaming agent is any one of fatty alcohol defoaming agent, ethanol, and n-propanol; the phosphoric acid defoaming agent is any one of tributyl phosphate and triisobutyl phosphate; the organosilicon defoaming agent is any one of pulp black liquor defoaming agent and general-purpose organosilicon defoaming agent.

Images