TW528728B - Improved continuous process for preparing microgels - Google Patents

Abstract

Silica deposits formed during a continuous process for preparing polysilicate microgel are removed and purged form the process by elastically deforming the vessel walls, reducing plugging. A continuous process for preparing a polysilicate microgel comprising, in sequence: (a) mixing a water soluble silicate aqueous solution and a gel initiator in a mixing vessel to produce an aqueous mixture having a silica concentration of 0.5% to 15%, by weight; and (b) aging the mixture in an elongated aging vessel to partially gel the mixture; wherein said mixing vessel and/or said aging vessel are elastically deformable and are temporarily deformed during the process to dislodge deposits formed on the vessel walls and purge the deposits from said vessel.

Description

W8728 V. Description of the invention (1 Field of the present invention Benfayueguanguan ## An improved continuous method for preparing polysarcoate microgels, whereby the silicon oxide deposits are reduced or eliminated. Relevant technical description is lacking-polysilicon Acid salt microgels (that is, an aqueous solution formed by the partial gelation of w ^ ip metal-silicon bismuth salts) are known in the art to shield φ pA. Zizinin has been well known. Generally, partially gelled This is achieved by mixing the alkali metal silicate with a gum initiator, ageing the mixture for a short period of time, and then diluting the mixture to stop gelling. Mineral acids and alum are the most commonly used gum initiators. The resulting The microgels have commercial applications, used as a drainage and water retention aid in papermaking, as a flocculant in portable drinking water purification plants and similar applications. Although it is an excellent flocculant and harmless to the environment At present, several practical factors limit the commercial use of polysilicate microgels. For example: the microgel gel must be diluted so that it is not practical to transport a large number of long distances. Microgels can become gels Trend And silicon oxide deposits are formed in the equipment used to prepare the products. These problems can be overcome in the factory environment by equipment design and trained personnel, but there are major difficulties in field application, and the equipment there must be equivalent Easy to operate and maintain. The batch method for generating microgels is: aging the microgels in a large mixing and holding tank, which is not only expensive, but also introduces product unevenness and process control in the original batch method. The problem. A continuous method to generate and age the microgels has excellent consistency in product quality. Unfortunately, the oxidized stone deposits in the batch containment tank can be reduced by -4 than in the continuous process pipeline. -^ Paper size applies Chinese National Standard (CNS) A4 (210 X 297 mm) (Please read the precautions on the back before filling this page)

Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs -------- Order --------- · 528728

Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs, which is better tolerated, the sediment in the continuous method will block the equipment and cause frequent shutdowns for maintenance. U.S. Patent Nos. 5,279,807, 5,505,820 and 5,658,055 disclose improved continuous processes for preparing polysilicate microgels, in which silicon oxide deposits are mixed with soluble silicon under specific conditions Acid solution and gum initiator are greatly reduced. When the designs led in these patents have resulted in significantly improved performance and found commercial use, silicon oxide deposits still often occur 'which clog the lines and instruments of the microgel generator. Therefore, it is necessary to maintain regular process shutdowns and dissolve enough with an alkali such as sodium hydroxide to exclude the deposits. If continuous production is required, a spare generator must also be maintained. Therefore, there is a need to further improve the method for preparing polysilicate microgels. '' Summary of the Invention The present invention provides an improved continuous method for preparing polysilicate microgels, which sequentially comprises: (a) mixing an aqueous solution of a water-soluble silicate with a gel initiator in a mixing container, Producing an aqueous mixture having a silica concentration of about 0.5% to 15% by weight; and (b) aging the mixture in an elongated aging container to partially gel the mixture; and wherein the mixing container and / or the The aging container is elastically deformable and can be temporarily deformed during the manufacturing process to remove the deposit formed on the vessel wall and discharge the deposit from the container. · Install -------- Order --------- (Please read the precautions on the back before filling this page) -5- A7

V. Description of the invention (3) In a preferred embodiment, the mixing in step (a) is carried out under the conditions described in US Patent Nos. 5'279,807 '5,503,820 and 5,65 8,055. ♦ Formation is minimized. The ions can also be present in step (a) this combination 'to form a modified polysilicate microgel that requires less aging time in step (b). Conveniently, use a flexible tube for the mixing and / or aging container. The tube is pressed through the tube by increasing or decreasing the pressure in the tube, or by mechanical means such as a roller set of rollers along the length of the tube, and the valley is easily deformed. Ultrasound or sonic can be used on semi-rigid or polymeric containers. The description of the county example is a polysilicate microgel, which is an aqueous solution formed by partially bonding an alkali metal silicate or a polysilicate, such as sodium polysilicate, which has the most common form. Shao Na 2 0 to 3.3 weight part of Si 2. The microgel is composed of water and linked silica particles having a diameter of 1 to 5 mm and a surface area of at least 5000 m 2 / g. The particles are bound together during the preparation (ie, during the 4-blade cementing period) to form a micelle with a three-dimensional network and bonds. This microgel solution has a low s compared to commercial colloidal hafnium oxide. This is as defined in El) and Doulton (〇 州 〇11); phys 6J) (1956), pages 955-957, is the weight of the oxide in the dispersed phase /. , Which is interpreted as the amount of micelles of the silica particles. The colloidal silica is shown in terms of Al and Daton, and is generally in the range of 80% to 90%. The oxide content of the oxidized stone microgel solution is generally less than 50%, and preferably less than 40%. i -------------- ^ --------- (Please read the precautions on the back before filling out this page) Printed by the Staff Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs-6 -

528728 A7 B7 V. Description of the invention (4) When the pH is lower than 5, polysilicate microgels are sometimes referred to as polysilicate microgels. As p Η increases, these products may contain a mixture of polysilicic acid and polyacrylic acid salt microgels, with a ratio depending on ρ Η. As used herein, the term "sugar salt and salt salt gel" includes this mixture of polyacrylic acid and polylithium salt microgels. Polysilicate microgels usually contain aluminate ions in their structure. The modification salt can be present in the entire polysilicate micelle, or only on its surface, depending on where the aluminum source is added to the process. Aluminum can be added to increase the rate of microgel formation And thus reduce the aging time. Aluminum also allows the microgel to maintain its charge under low pH conditions. The term used herein " polysilicate microgel " includes aluminum-containing polysilicate microparticles Gels, which are sometimes referred to in the art as polyaluminosilicate microgels. J Kunhe can choose a conventional water-soluble silicate solution and a gel initiator to form the mixture in step (a), which has a concentration of silica ranging from 0.5% by weight to 0.5% by weight, It is preferably 1% to 0% by weight. The microgels usually form too slowly for practical use at concentrations below 0.5%. Above 15% silica, the rate of cementation is too fast to be effectively controlled. Suitable gum initiators are well known in the art and include acid exchange resins, mineral acids, organic acids, acid salts, acid gases, metal salts of amphoteric metal acids (such as aluminate steel), and organic compounds, Such as: certain anhydrides, amidines, esters, lactones, nitriles, and sulfonamides. Mineral acids, typically sulfuric acid, and alum are common gum initiators. The gum initiator can be added with an aqueous concentrate, which can reach the limit of its solubility, or it can be diluted (please read the precautions on the back before filling this page). Loading -------- Order- --------, Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs

528728

Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs. 5. Description of the Invention (5) Solution to accelerate mixing. When the gum initiator is a mineral acid, the resulting mixture has a P Η range of 2 to 10, and the acid flow rate (or ratio to silica) is generally controlled by a ρ Η control system. If an organic acid is selected as the gel initiator, such as: carbonic acid or carbon dioxide, the flow rate of the gel initiator and / or the silica solution can be controlled by volume (in the range of pH 2 to 10) because of the slowness of the obtained carbonic acid. Rush effect. Volume control provides the advantage of avoiding a pH sensor that requires frequent cleaning, calibration, and replacement. If the selected gel initiator is alkaline, such as a solution of sodium bicarbonate or sodium aluminate, it is convenient to control the volume flow rate of the gel initiator and / or silicate solution, because both streams are alkaline of. The resulting mixture has a pH range of 7 to 1.3. If desired, the aluminum salt is conveniently added to the gum initiator or silicate solution as component A 'or another stream that can be separated and added to the mixture. in. An excellent polysilicate silicate microgel is prepared by adding an aluminum salt to a stream of the acid gel generator, and its portion yields an Al2O3 / Si02 molar ratio ranging from 1: 1,500 to 1 : 25, preferably i: i, 250 to 1: 5ο. In addition, the polysilicate microgel is prepared by using a polyaluminosilicate solution. The polyaluminosilicate solution is prepared by directly reacting an alkali metal aluminate with a silicate to form Al2O3. The Mo / SiO2 mole ratio is as high as about 2: 1. When any mixing conditions can be used in the practice of the present invention, it is particularly preferred to use the mixing conditions as guided in U.S. Patent Nos. 5,279,807, 5,503,820, and 5,658,055; herein incorporated by reference. The severe mixing conditions described here have been found to greatly reduce the colloid and oxygen during the aging of microgels. 8-size applies to Chinese National Standard (CNS) A4 (210 X 297 public love) (Please read the precautions on the back first) (Fill in this page again) -------- Order --------- · A7 B7 、 Invention description (6 Printed by the Intellectual Property Bureau Staff Consumer Cooperatives of the Ministry of Economic Affairs 2 The formation of deposits, and reached ㈣Salt solution and gel initiator flow collection: within a range of: 0 °; or (ii) use a ring-shaped mixing device 'wherein it is released from the internal officials-flow to the outer loop The second stream, and the two streams of Huimu. When the present invention does not require severe mixing conditions, it is preferred that the Reynolds number in the mixing zone is at least 丨, _, which is more than 630,000 The mixture is ageed—for a sufficient period of time to achieve the desired degree of cementation, which usually takes at least 10 seconds but not more than 15 minutes. Partial cementation produces a three-dimensional micelle network of high surface area silica particles. Roads and chains are known in the art as polypetrate microgels. The desired degree of gelling It varies with the selected ingredients and applications, but usually produces complete gelling in the brain to 9.% of the time. As a result, the skilled artisan can easily measure the flow rate by changing the flow rate through the aging container. Gel time and adjust the selected aging time. For example: the length and / or diameter of the aging container, and, the cloud # λ μ Iization. And the dynamic pressure can be used in the continuous method for special applications. 'Aging occurs when the mixture passes through an elongated container and must be completed when the mixture reaches the outlet of the container. The elongated capacity generally has a fixed diameter (ie: pipeline) to a selected diameter length To provide the dwell time so that the mixture "ages to the desired degree of privacy." The aging container has a diameter ranging from M cm to 2 $ cents (1 M to 10 mm) and a length of 60 cm To 150 meters (2 to 500 sighs) to provide a residence time of 10 seconds to 15 minutes. Usually, a time of 15 minutes or longer is used (Please read the precautions on the back before filling out this page) --- ----- Order .--------. Bu paper scale 剌 China Home mark iTcNS) A4 size (21〇: -9 ·

Spoon residence time has no merit. According to the present invention, the mixture is formed and / or aged in an elastically deformable, elongated container (such as a pipeline or officer), which is sometimes temporarily deformed to remove deposits formed on the vessel wall. As it continues through the container, the removed deposits are discharged from the container as an aged mixture. This deposit consists of silicon oxide; for many applications, it is not necessary to separate and remove it from the mixture leaving the vessel. The advantages of the present invention are particularly evident when used in the mixing and early aging steps, with particular tendency to form deposits. The grainer can include auxiliary equipment such as valves, mixers, and process instruments. The trough is constructed with a material that has a higher elasticity than silicon oxide deposits, and (ii) a surface property that allows the container to deform to overcome the adhesion between the container and the deposit. Therefore, when the container deforms, the deposit is caused Removal. The selected material will vary with the selected device to temporarily deform the wall. The material usually has a smooth surface to assist in the removal of oxidized stone deposits. In one embodiment, the wall of the container is expanded or contracted by increasing or decreasing the internal pressure of the container, while temporarily deforming the wall surface. This pressure change can be achieved by any method known in the art, such as: (i) periodically changing the pressure of the feed stream; (ii) using a feed pump with discontinuous feeding characteristics, such as a piston pump; (iii) Periodically control the flow resistance of the valve with a program; periodically introduce a liquid or gas, or a combination thereof, that does not unduly affect the aging process. In this embodiment, examples of suitable materials for constructing the container include: polymer materials, such as: vinyl plastic, "Viton" co-fluorinated polymer, "Teflon" polytetrafluoroethylene Fluoroethylene, silicone rubber, polybutylene rubber and its -10- t S @ (CNS) A4liiT210 x 297 ^ (Please read the precautions on the back before filling this page) --------- · Printed by W728 A7, Consumer Cooperatives, Intellectual Property Bureau, Ministry of Economic Affairs

Member of the Intellectual Property Bureau of the Ministry of Economic Affairs, X Consumer Cooperative, printed 1 rubber or elastomer, which can withstand regular elastic deformation without breaking I 'and has chemical resistance to aging mixtures. In a second embodiment, the container is temporarily deformed by applying a mechanical force to the wall. This mechanical force can be applied by any known device in the art, including but not limited to squeezing, or bending and releasing the wall surface with rollers, presses, or other mechanical devices, and changing the pressure of the surrounding fluid. The application of the mechanical force ^ may be to lengthen the container longitudinally to reduce its diameter and then load the dagger. A particularly preferred method is one in which one or more pairs of rollers are moved along the tubular container = longitudinal axis. This particular embodiment would select a similar phase as described above, where the internal pressure of the container would vary. In three specific embodiments, the wall of the device is temporarily deformed by a vibration force, such as: vibration is transmitted from a liquid having a submerged vibrator around to the container. Generally for this purpose, an ultrasonic vibrator is chosen. In addition, the mixture contained in this container can vibrate and transmit vibrations, causing the container to deform elastically. In this specific embodiment, the container is generally constructed of a semi-rigid material, such as steel or non-recorded steel, which has greater elasticity than oxygen cut sinkers, or polymer materials as described above. Polysilicate microgels are usually processed to stop or have a minimal amount of further gel formation. This treatment can be a simple dilution step, which reduces oxygen

If the temperature is less than 1G% by weight, preferably less than 5% by weight, or the pH step, or a combination of dilution and pH adjustment, the gelation is stopped or: stagnant or both . Other techniques known in the art can be chosen to stop the formation of glue. Loading -------- Order --------- CPlease read the notes on the back before filling in this page) -11-^ 28728

V. Description of the invention (9 Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs, and then the microgels can be searched for $ ,, 若, π, 合, and the desired use. In addition, then ": was consumed for many moments" If due to its intended use, it can be further gelatinized, no need to dilute or adjust the microgel 5IP. Right, the aged microgel can be filtered to remove the unacceptable oxidation of the maggot Silicon deposits, which will be excluded in the practice of the present invention. The polycalcium salt microgels prepared in this article can be used to consume this micro: ... for the purpose of whitening the glue, In use, the microparticles: glue can be reliably produced in this field. For example, the microgel can be used as a coagulant to remove bone cement from an aqueous suspension, or as a water-holding aid for paper, often with other Polymers and / or chemicals are used for this purpose. The present invention has been described, and is now illustrated by the following examples, but is not limited thereto. Example Example 1 The preparation of a polyaluminosilicate particulate gel solution is Dilute sodium silicate solution with dilute sodium aluminate The solution was reacted in a ring-shaped connection mixer. That is, a sodium oxalate solution containing 2% by weight of Si02 was passed through a Swagelok ½ inch (1.27 cm) T-tube at 1.9 gallons (7.2 liters per minute) was fed into a circular reaction zone. The τ-shaped tube was connected to a 100-in. (30.5-m) L2-inch (丨 27 cm) diameter reinforced Tygon ) [B44-4K formula plastic tube, available from Norton Performance Plastics Corp., Wein, New Jersey,

Wayne, New Jersey). Sodium aluminate solution containing 2% by weight of Al2O3 passes through -12- This paper size applies Chinese National Standard (CNS) A4 specification (2Ox 297 mm) ---- 1 .--.----- -· U--p--Λι --- Order --------- (Please read the precautions on the back before filling out this page) 528728 A7 B7 Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs Description of the invention) A 1/4 inch (0.635 cm) diameter stainless steel tube is introduced into the annular mixing zone through a 1/2 inch T-shaped tube about 8 inches (20 cm) downstream of the silicate. ▲ Ming salt is fed into the mixing zone at a rate that maintains Ak / 6 / SiO2 weight ratio of 1/6. The mixing of Shixi's old salt and ming acid salt was completed in a Tygon tube. The gasified deposits in the Tygon official became apparent after about an hour of operation. The sediment was removed by passing the pipeline between two plastic rollers and squeezing the Tygon tube slightly. After passing the roller once, no silicate deposits were found in the tube. A total of about 400 gallons (15 14 liters) of polyaluminosilicate particulate gel solution was prepared using the apparatus described above. All silicate deposits were removed from the device using plastic rollers to deform the pipeline. The polyaluminosilicate particulate gel solution was found to be excellent in water holding and drainage aids for paper making. Example 2 This example illustrates how to use ultrasonic vibration to elastically deform a process container while avoiding the formation of silicon oxide deposits when a polyaluminosilicate particulate gel solution is produced. Diluted 3.2 ratio of sodium silicate and sulfuric acid are mixed in a stainless steel T-shaped mixer, and at an average flow rate of pH 8 7 and 13 gallons per minute (49 liters per minute), 3.2 weights are produced. % SiO solution. After leaving the T-junction mixer, the solution was introduced into a reinforced Thai steel tube with an inner diameter of i-7 m) (0.95 cm) long. Tycoon tube is then connected to a section of stainless steel tube with an outer diameter of 8 忖 (20 cm) and a length of 1/2 (1.27 cm). This stainless steel tube is then connected to a section of 6 pairs (15 cm) of polyvinyl chloride. T «on rubber-lined elastic tube. The downstream of the poly-gas sintering liner is connected to the Mu Deyi rust-adding device —... (Please read the precautions on the reverse side before filling out this page) -13- For the paper size, Zhongguanjia standard is 297 mm) 528728

Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs A7 V. Description of the invention (11) (Lakewood instruments) pH electrode combination of type 72 to control the pH of the petrate / acid mixture. The polychloroprene rubber-lined tube, stainless steel, and a portion of the Tygon tube were immersed in a Branson Model 3200 ultrasonic bath operating at 4 to 7 kilohertz (kHz). After operation at 65 o'clock, no silica deposits are visible in any of the lines immersed in the ultrasonic bath. On the pH electrode combination not in the ultrasonic bath, a clear coverage of silicon oxide deposits was seen. The combination was soaked in warm sodium hydroxide solution i and oxidized; the sediment can be removed from the PP electrode assembly. Analysis of the sodium hydroxide solution revealed that 0.77 g of SiO was deposited on the pH electrode assembly. Example 1 This example shows how to use ultrasonic vibration to elastically deform a process container while avoiding the formation of aluminosilicate deposits when a polyaluminosilicate microgel solution is produced. 100 ml / min of 2% by weight SiO2, sodium silicate diluted at a ratio of 3.2, and 20 ml / min of 2% by weight A1 of sodium aluminate solution were mixed in a T-shaped mixer. The mixed solution was pumped through a stainless steel tube with an outer diameter of 1/4 inch (0.635 cm). The stainless steel tube was connected to a section of Nalgene 180 transparent plastic special tube, Class VI, 5/32 inch (0.4 cm) on the inside diameter. A part of the Nalgene tube was immersed in a Brasson model 3200 ultra wave bath operating at 4 to 7 kilohertz (kHz). All stainless steel tubes were immersed in the ultrasonic bath except at about ^ ”(centimeters) at both ends. After about i hours, there was a significant difference in the Nalgene tube outside the ultrasonic bath. Aluminosilicate deposits. Deposition in a Nalgene tube outside the ultrasonic bath. --1 (Please read the notes on the back before filling this page)

x 297 mm) 528728 A7 B7 V. Description of the invention (12 :. It can be easily removed by deforming the pipeline, such as: stretched, bent or squeezed 4 hours after the production of polysilicate microgel, dip No deposits were found in the Nalgene tube of the ultrasonic bath 2. No deposits were found in the stainless steel tube 2 either, indicating that the ultrasonic bath caused immersion in the ultrasonic bath and a distance outside the ultrasonic h bath. The stainless steel tube is deformed elastically. Example 4 Printed by the Consumers ’Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs When deforming a glass container with a low elasticity, it creates a pressure greater than the formed "silicate = the adhesion strength of the product. 100 liters / minute containing 2% by weight SiO2, a dilution ratio of 3.2 Sodium silicate is mixed with 20 ml / min of a 2 weight sodium aluminate solution in a τ-connected mixer. The mixture is suitable for passage through a 6 忖 (15 cm) length 5/32 忖(040 cm) inner diameter; glass tube pumped in. About 3 inches 7.5 cm) glass tube was immersed in a Branson model 3200 ultrasonic bath operating at 叼 kilohertz (kHz). The glass tube was connected to a 1/4 inch (0.635 cm) inner diameter A part of the transparent plastic tube was also immersed in the ultrasonic bath. After about 1 hour, the whole glass section (inside and outside the ultrasonic bath) and Nalgene outside the ultrasonic bath A part of the tube had clearly visible aluminosilicate deposits. After 4 hours of operation where the entire glass tube was covered with broken salt deposits, the Nalgene tube immersed in the ultrasonic bath was not visible -15- This paper size applies Chinese National Standard (CMS) A4 (210 X 297 mm)

Claims (1)

"^ 5 " Patent Application No. 4 ^ Chinese Application ^ Amendment of Patent Scope (9 Amendment of Patent Scope (June 91) A8 B8 C8 D8« L 6. The scope of the patent application is supplemented by a continuous method for preparing polyacrylate microgels, which sequentially includes: (a) mixing an aqueous solution of a water-soluble silicate with a gum initiator in a mixing trough to produce a An aqueous mixture having a silica concentration of 0.5% to 15% by weight; and (b) aging the mixture in an elongated aging container to partially gel the mixture; wherein the mixing container and / or the aging container are It is elastically deformable and can be temporarily deformed during the production process to remove the deposit formed on the vessel wall and discharge the deposit from the container. 2. The method of claim 1 in which the elongated container is temporarily deformed to increase the internal pressure of the container. 3. The method according to the scope of application for patent, wherein the container is temporarily deformed to reduce the internal pressure of the container. 4. The method according to item 1 of the patent application range, wherein the container is temporarily deformed by periodically changing the external flow resistance. 5. The method of claim 1 in which the container is mechanically deformed to temporarily deform the container. 6. The method of claim 5 in which the mechanical force is applied by a wave, a squeeze, or an external pressure fluid. 7. The method of claim 6, wherein the mechanical force is applied by moving one or more pairs of rollers along the longitudinal axis of the container. 8. The method of claim 1 in which the container is temporarily deformed by exposure to vibration. 9. If the method of applying for the item No. 8 of the patent scope, wherein the vibration has been immersed in this paper, the size of the paper applies the Chinese National Standard (CNS) A4 specification (210 X 297 mm) 8 8 8 8 A BCD VI. Patent Application Scope The liquid surrounding the vibrator is transferred to the container. 10. A method as claimed in claim 8 wherein the mixture aged in the container transmits vibrations to the container. -2- This paper size is applicable to China National Standard (CNS) A4 (210 X 297 mm)