An antifoaming agent, its preparation method and application

Abstract

This invention discloses an defoamer, its preparation method, and its application. By weight, it comprises the following components: 100-110 parts silicone paste; 5-8 parts polyether-modified silicone oil; 10-20 parts surfactant; 2-4 parts dispersing agent; and 200-250 parts distilled water. Based on the weight of the silicone paste, the silicone paste is prepared from raw materials comprising the following components: 100 parts organosiloxane; 6-8 parts active particles; and 1-1.5 parts silane coupling agent. The anionic surfactant of this invention helps to improve the defoaming speed of the defoamer, while simultaneously increasing the cloud point of the nonionic surfactant and improving its high-temperature resistance to prevent demulsification and failure. The nonionic surfactant assists in the fusion of the components in the defoamer, making it less prone to stratification and improving the defoamer's performance. Specifically, this invention involves adding the defoamer to the extraction and rinsing stages of black liquor during the pulping process in paper mills to achieve defoaming treatment of the black liquor.

Description

Technical Field

[0001] This invention relates to the field of papermaking chemicals, specifically to an antifoaming agent, its preparation method, and its application. Background Technology

[0002] Wastewater from the alkaline pulping process (caustic soda process and sulfate process) in the papermaking industry contains a large amount of lignin, giving it a dark brown color; this is known as black liquor. Black liquor is prone to foaming, mainly because a large amount of organic lignin, especially from pine wood, dissolves during the cooking process. After cooking, the high content of turpentine saponification results in fine, strong foam, which is also highly alkaline, viscous, and hot. Even with the use of defoamers, the adhesives in the black liquor easily clump together and clog the screen, reducing the washing effect and affecting the quality of the wood pulp.

[0003] Currently, silicone defoamers offer the best defoaming effect. Commonly used silicone defoamers are typically prepared as water-emulsion products by emulsifying a complex of dimethyl silicone oil and SiO2 using an emulsifier. The mechanism of action of silicone defoamers mainly involves the dispersion of hydrophobic SiO2 with a large specific surface area in dimethyl silicone oil. Due to the presence of SiO2 particles, the silicone oil can quickly spread in the foaming liquid, improving the dispersion efficiency of the silicone oil and thus enhancing the defoaming effect. Furthermore, an important function of SiO2 in defoamers is adsorption. Due to its small particle size, large specific surface area, high surface energy, and three-dimensional network structure, SiO2 can form a powerful adsorption force on bubbles. Together with silicone oil, it constitutes a force that attacks the bubbles. Specifically, SiO2 adsorbs and impacts the bubbles, creating weak points. Under the action of the low surface tension of silicone oil, the bubbles rupture, leading to bubble breakage. In other words, SiO2 in defoamers acts like a "needle tip," rapidly causing bubbles to break and achieving defoaming and foam suppression. However, papermaking black liquor, especially pine pulp black liquor, has high viscosity, high temperature, strong alkalinity, and fine bubbles. SiO2 will decompose under high temperature and strong alkaline conditions, resulting in a decrease in defoaming and foam suppression effects, and it is easy to break the emulsion, which leads to an increase in adhesives and poor dispersion. Summary of the Invention

[0004] To address the above problems, this invention provides a defoamer, its preparation method, and its application. When defoaming papermaking black liquor, especially pine pulp black liquor, it defoams quickly, suppresses foam for a long time, and requires very little dosage.

[0005] According to the purpose of this invention, an antifoaming agent is provided, comprising the following components by weight:

[0006] 100-110 parts of silicone paste;

[0007] 5-8 parts of polyether-modified silicone oil;

[0008] 10-20 parts of surfactant;

[0009] 2-4 parts of dispersing agent;

[0010] 200-250 parts distilled water.

[0011] Based on the weight parts of the silicone paste, the silicone paste is prepared from raw materials comprising the following components:

[0012] 100 parts of organosiloxane;

[0013] 6-8 parts of active particles;

[0014] 1 to 1.5 parts of silane coupling agent.

[0015] Preferably, the organosiloxane includes dimethyl silicone oil and hydroxyl silicone oil.

[0016] Preferably, the hydroxyl silicone oil includes hydroxyl-terminated polysiloxane and dihydroxyl-terminated polysiloxane with a hydroxyl content of 3-8%, and hydroxyl silicone oil with a viscosity of 50-100,000 cst.

[0017] More preferably, the hydroxyl silicone oil includes hydroxyl silicone oil with a viscosity of 10,000 to 100,000 cst.

[0018] Most preferably, the hydroxyl silicone oil comprises a hydroxyl silicone oil with a viscosity of 30,000 to 60,000 cst.

[0019] Preferably, the active particles include zeolites, molecular sieves, and metal-organic frameworks (MOFs).

[0020] More preferably, the zeolite is 4A zeolite, the molecular sieve includes 3A / 4A / 5A / 13X molecular sieve, and the metal-organic framework materials (MOFs) include MOF-5, MOF-74, and ZIF-8.

[0021] Most preferably, the active particles are selected from 4A molecular sieve and MOF-5.

[0022] Preferably, the method for preparing the silicone paste includes the following steps:

[0023] Organosiloxane, active particles and silane coupling agent are mixed and reacted at 80~110℃ for 3~6h to obtain silicone paste.

[0024] Preferably, the surfactant includes anionic surfactants, amphoteric surfactants, and nonionic surfactants.

[0025] Preferably, the dispersing agent includes sodium pyrophosphate, sodium polyphosphate, and acrylic acid-maleic anhydride polymer.

[0026] This invention provides a method for preparing the defoamer described in the above technical solution, comprising the following steps:

[0027] The defoamer is obtained by mixing silicone paste with polyether-modified silicone oil and surfactant, mixing dispersant and distilled water, and then adding the aqueous phase solution to the oil phase solution at 60-80℃.

[0028] This invention provides the application of the defoamer described in the above technical solution or the defoamer prepared by the preparation method described in the above technical solution in the defoaming treatment of papermaking black liquor.

[0029] In this invention, the raw materials for preparing the silicone paste include 100 parts of organosiloxane. Preferably, the organosiloxane comprises dimethyl silicone oil and hydroxyl silicone oil. The preferred mass ratio of dimethyl silicone oil to hydroxyl silicone oil in the organosiloxane is (1.5~2.4):1, more preferably (1.8~2.2):1, and most preferably (2.0~2.1):1.

[0030] In this invention, the dimethyl silicone oil preferably comprises low-viscosity dimethyl silicone oil and high-viscosity dimethyl silicone oil; the viscosity of the low-viscosity dimethyl silicone oil is preferably 300-500 cst, more preferably 350-450 cst; the viscosity of the high-viscosity dimethyl silicone oil is preferably 3000-10000 cst, more preferably 5000-8000 cst. In this invention, the mass ratio of low-viscosity dimethyl silicone oil to high-viscosity dimethyl silicone oil is preferably (1.5-8.5):1, more preferably (3-7):1, and most preferably (4-6):1. This invention does not have a special limitation on the source of the dimethyl silicone oil; commercially available dimethyl silicone oils known to those skilled in the art can be used.

[0031] In this invention, the hydroxyl silicone oil is most preferably a hydroxyl silicone oil with a viscosity of 30,000 to 60,000 cSt. This invention does not have a specific limitation on the source of the hydroxyl silicone oil; commercially available hydroxyl silicone oils well-known to those skilled in the art can be used.

[0032] In this invention, the raw materials for preparing the silicone paste include 6-8 parts of 4A molecular sieve or MOF-5, preferably 6.5-7.5 parts, and more preferably 7 parts. This invention does not have a specific limitation on the source of the active particles; commercially available products are acceptable. In this invention, the active particles have a larger specific surface area and do not decompose under high temperature and alkaline conditions, thus maintaining a long-lasting defoaming and foam-suppressing effect. The specific surface area of ​​the fumed silica is 200-400 m² / g. 2 / g, while the specific surface area of ​​4A molecular sieve can reach 600m². 2 / g, MOF-5 has a specific surface area of ​​up to 2000m². 2 / g.

[0033] In this invention, the raw materials for preparing the silicone paste include 1-1.5 parts of a silane coupling agent, preferably 1.1-1.4 parts, and more preferably 1.2-1.3 parts. In this invention, the silane coupling agent preferably includes silane coupling agents KH550 and / or KH560. When the silane coupling agent includes silane coupling agents KH550 and KH560, this invention does not have a specific limitation on the addition ratio of silane coupling agents KH550 and KH560, and any addition ratio can be used; preferably, the addition ratios of silane coupling agents KH550 and KH560 are equal. In this invention, the silane coupling agent plays a bridging role in the defoamer, which can improve the bonding force between organosiloxane and silica, making silica less prone to precipitation, stable under alkaline conditions, and less prone to decomposition, thus improving the alkali resistance of silica and consequently improving the performance of the defoamer.

[0034] The defoamer provided by this invention comprises 5-8 parts of polyether-modified silicone oil, preferably 6-7.5 parts, and more preferably 7 parts. This invention does not specifically limit the type or model of the polyether-modified silicone oil; any polyether-modified silicone oil well-known to those skilled in the art can be used. In the embodiments of this invention, Dow Corning OFX-0190 polyether-modified silicone oil and Jiaxing Yincheng Chemical 204 polyether-modified silicone oil are specifically used. In this invention, the polyether-modified silicone oil can improve the foam-suppressing effect of the defoamer.

[0035] The defoamer provided by this invention comprises 10-20 parts of surfactant, preferably 12-18 parts, and more preferably 15-16 parts. In this invention, the surfactant preferably includes anionic surfactants, amphoteric surfactants, and nonionic surfactants. In this invention, the mass ratio of the anionic surfactant, amphoteric surfactant, and nonionic surfactant is preferably (0.5-1):(0.5-1):(4-7), more preferably (0.6-0.9):(0.6-0.9):(4.5-6.5), or (0.7-0.8):(0.7-0.8):(5-6).

[0036] This invention does not specifically limit the type of anionic surfactant; any anionic surfactant well-known to those skilled in the art can be used, such as sodium di-2-octyl maleate sulfonate (fast penetrant T). In this invention, the anionic surfactant helps to improve the defoaming speed of the defoamer, while simultaneously increasing the cloud point of the nonionic surfactant and improving its high-temperature resistance to prevent demulsification and failure.

[0037] This invention does not specifically limit the type of amphoteric surfactant; any amphoteric surfactant well-known to those skilled in the art, such as lecithin, can be used. In this invention, the amphoteric surfactant can assist in the fusion of the components in the papermaking black liquor defoamer, making it less prone to stratification and thus improving the defoamer's performance.

[0038] This invention does not specifically limit the type of nonionic surfactant; any nonionic surfactant well-known to those skilled in the art can be used. In this invention, the nonionic surfactant is preferably a polyether-based nonionic surfactant, more preferably including fatty alcohol polyoxyethylene ether and fatty alcohol polyoxypropylene ether. In this invention, the mass ratio of the fatty alcohol polyoxyethylene ether to the fatty alcohol polyoxypropylene ether is preferably (2~3):(2~4), more preferably (2.2~2.8):(2.5~3.5), and most preferably 2.5:3. This invention does not specifically limit the type of fatty alcohol polyoxyethylene ether; any fatty alcohol polyoxyethylene ether well-known to those skilled in the art can be used, specifically such as isomeric decaol polyoxyethylene ether. This invention does not specifically limit the type of fatty alcohol polyoxypropylene ether; any fatty alcohol polyoxypropylene ether well-known to those skilled in the art can be used, specifically such as cetearyl alcohol polyoxypropylene ether. In this invention, the nonionic surfactant can assist in the fusion of the components in the defoamer, making it less prone to stratification, which is beneficial to improving the performance of the defoamer; at the same time, it can improve the foam-suppressing effect of the defoamer.

[0039] The defoamer provided by this invention includes 2-4 parts of dispersing aid to improve the dispersion stability of active particles.

[0040] This invention provides the application of the defoamer described in the above-described technical solutions or the defoamer prepared by the above-described preparation methods in the defoaming treatment of papermaking black liquor. This invention does not impose any particular limitation on the application method of the defoamer in the defoaming treatment of papermaking black liquor; any application method well known to those skilled in the art can be used. Specifically, in this invention, the defoamer is added during the extraction and rinsing stages of papermaking black liquor in the pulping process of a paper mill to achieve defoaming treatment of the papermaking black liquor.

[0041] The beneficial effects of this invention are:

[0042] This invention utilizes anionic surfactants to improve the defoaming speed of defoamers, while simultaneously increasing the cloud point and improving the high-temperature resistance of nonionic surfactants to prevent demulsification and failure. Nonionic surfactants assist in the fusion of components within the defoamer, preventing stratification and improving its effectiveness; they also enhance the defoaming suppression effect. Dispersing agents improve the dispersion stability of active particles. Specifically, this invention involves adding a defoamer during the extraction and rinsing stages of black liquor extraction in paper mill pulping to achieve defoaming treatment of the black liquor. Detailed Implementation

[0043] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0044] Example 1

[0045] A method for preparing an antifoaming agent includes the following steps:

[0046] (1) By weight, 100 parts of organosiloxane (including 50 parts of dimethyl silicone oil with a viscosity of 350~450cst, 15 parts of dimethyl silicone oil with a viscosity of 5000~8000cst, and 35 parts of hydroxyl silicone oil with a viscosity of 30000cst) are heated to 50°C and mixed with 6 parts of 4A molecular sieve and 1 part of silane coupling agent KH550 under stirring. The temperature is then raised to 100°C and reacted for 5 hours to obtain silicone paste.

[0047] (2) The silicone paste in step (1) is mixed with 6 parts of polyether modified silicone oil (Dow Corning OFX-0190 model) and 14 parts of surfactant (including 9 parts of cetearyl alcohol polyoxypropylene ether and 5 parts of isomeric decaol polyoxyethylene ether) for the first time and stirred for 1.5 hours to obtain the initial mixture.

[0048] (3) Cool the initial mixture in step (2) to 60°C, dissolve 2 parts of sodium pyrophosphate in 200 parts of distilled water, add it to the initial mixture in step (2) for secondary mixing, stir for 1.5 hours, and obtain defoamer.

[0049] Example 2

[0050] A method for preparing an antifoaming agent includes the following steps:

[0051] (1) By weight, 100 parts of organosiloxane (including 45 parts of dimethyl silicone oil with a viscosity of 350~500cst, 25 parts of dimethyl silicone oil with a viscosity of 5000~6000cst, and 30 parts of hydroxyl silicone oil with a viscosity of 10000cst) are heated to 50°C and mixed with 7 parts of MOF-5 and 1.5 parts of silane coupling agent KH550 under stirring. The temperature is then raised to 110°C and the initial reaction is carried out for 3 hours to obtain silicone paste.

[0052] (2) The silicone paste in step (1) is mixed with 8 parts of polyether modified silicone oil (Yincheng Chemical 204 model) and 18 parts of surfactant (including 1.5 parts of fast penetrant T, 1.5 parts of lecithin, 9 parts of cetearyl alcohol polyoxypropylene ether and 6 parts of isomeric decaol polyoxyethylene ether) for the first time and stirred for 1 hour to obtain the first mixture.

[0053] (3) Cool the initial mixture in step (2) to 70°C, dissolve 4 parts of acrylic acid-maleic anhydride polymer in 240 parts of distilled water, add it to the initial mixture in step (2) for secondary mixing, stir for 1 hour, and obtain defoamer.

[0054] The performance of the papermaking black liquor defoamers prepared in Examples 1-2 of this invention was tested, and the results are shown in Table 1. The specific steps are as follows:

[0055] 100 mL of black liquor from a paper mill was used as the foaming agent. The foam was circulated using a bubbler to create a foam height of 20 cm. 5 μL of defoamer was added (the defoamer was the paper mill black liquor defoamer in Examples 1-2 of this invention). The time it took for the defoamer to eliminate 10 cm of foam and the foam suppression time were recorded.

[0056] Table 1. Comparison of performance between the papermaking black liquor defoamer and commercially available defoamers in Example 3 of this invention.

[0057] Types of defoamers Time required to remove 10cm of foam Foam suppression time Adhesive Example 1 3.3 seconds 8 minutes and 25 seconds trace amounts Example 2 3.0 seconds 8 minutes and 54 seconds trace amounts Commercially available products 3.9 seconds 7 minutes and 11 seconds More

[0058] The test results above show that the defoamer provided by this invention can quickly defoam and suppress foam for a long time when defoaming papermaking black liquor, and produces very little adhesive residue, which is superior to commercially available defoamer products.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An antifoam agent characterized in that, By weight parts, including the following components: Silicone paste 100~110 parts; Polyether modified silicone oil 5~8 parts; Surfactant 10~20 parts; Dispersion aid 2-4 parts; Distilled water 200-250 parts; The silicone paste is prepared from raw materials including the following components, with the weight parts of the silicone paste as the basis: Organic siloxane 100 parts; Active particles 6~8 parts; Silane coupling agent 1~1.5 parts; The active particles include zeolites, molecular sieves and metal organic framework materials (MOFs), the zeolites are 4A zeolites, the molecular sieves include 3A / 4A / 5A / 13X molecular sieves, and the metal organic framework materials (MOFs) include MOF-5, MOF-74 and ZIF-8; The preparation method of the silicone paste includes the following steps: mixing organic siloxane, active particles and silane coupling agent, and reacting at 80~110℃ for 3~6h to obtain a silicone paste; The surfactant includes anionic surfactants, amphoteric surfactants and nonionic surfactants; The dispersion aid includes sodium pyrophosphate, sodium polyphosphate and acrylic acid-maleic anhydride polymer.

2. The defoaming agent according to claim 1, characterized in that, The organic siloxane includes dimethyl silicone oil and hydroxy silicone oil, and the mass ratio of the dimethyl silicone oil and the hydroxy silicone oil is preferably (1.5~2.4):1; the hydroxy silicone oil includes hydroxy-terminated polysiloxane and dihydroxy-terminated polysiloxane with a hydroxyl content of 3~8%, and hydroxy silicone oil with a viscosity of 50~100000cst.

3. The defoaming agent according to claim 2, characterized in that, The dimethyl silicone oil preferably includes low-viscosity dimethyl silicone oil and high-viscosity dimethyl silicone oil; the viscosity of the low-viscosity dimethyl silicone oil is preferably 300~500cst; the viscosity of the high-viscosity dimethyl silicone oil is preferably 3000~10000cst; The mass ratio of low-viscosity dimethyl silicone oil and high-viscosity dimethyl silicone oil in the dimethyl silicone oil is preferably (1.5~8.5):1; The hydroxy silicone oil includes hydroxy silicone oil with a viscosity of 30000~60000cst.

4. The defoaming agent according to claim 1, characterized in that, The active particles are selected from 4A molecular sieves and MOF-5.

5. The method of preparing an antifoam agent according to any one of claims 1 to 4, characterized in that, Including the following steps: Mixing the silicone paste with polyether modified silicone oil and surfactant, mixing the dispersion aid and distilled water, and then adding the aqueous phase feed liquid to the oil phase feed liquid at 60-80℃ to obtain a defoaming agent.

6. The use of a defoamer according to any one of claims 1 to 4, characterized in that The application of the defoaming agent in the defoaming treatment of papermaking black liquor.