TW202035466A - Process for producing superabsorbent particles - Google Patents
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- TW202035466A TW202035466A TW109102409A TW109102409A TW202035466A TW 202035466 A TW202035466 A TW 202035466A TW 109102409 A TW109102409 A TW 109102409A TW 109102409 A TW109102409 A TW 109102409A TW 202035466 A TW202035466 A TW 202035466A
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- C08F6/00—Post-polymerisation treatments
- C08F6/008—Treatment of solid polymer wetted by water or organic solvents, e.g. coagulum, filter cakes
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- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
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- C08F2/10—Aqueous solvent
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- C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
- C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B17/00—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement
- F26B17/02—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by belts carrying the materials; with movement performed by belts or elements attached to endless belts or chains propelling the materials over stationary surfaces
- F26B17/04—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by belts carrying the materials; with movement performed by belts or elements attached to endless belts or chains propelling the materials over stationary surfaces the belts being all horizontal or slightly inclined
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- B65G—TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS
- B65G45/00—Lubricating, cleaning, or clearing devices
- B65G45/10—Cleaning devices
- B65G45/12—Cleaning devices comprising scrapers
- B65G45/16—Cleaning devices comprising scrapers with scraper biasing means
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
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Abstract
Description
本發明係關於一種藉由聚合單體溶液或懸浮液來製備超吸收性顆粒之方法，其包含對空氣循環帶式乾燥器中之所得水性聚合物凝膠進行乾燥、研磨、分類且視情況熱表面後交聯，其中該水性聚合物凝膠藉助於振盪傳送帶引入至該空氣循環帶式乾燥器中，且返回傳送帶之頂面藉助於至少一個剝離器件來清潔。The present invention relates to a method for preparing superabsorbent particles by polymerizing a monomer solution or suspension, which comprises drying, grinding, sorting, and optionally heating the obtained aqueous polymer gel in an air circulating belt dryer. The surface is post-crosslinked, wherein the aqueous polymer gel is introduced into the air circulating belt dryer by means of an oscillating conveyor belt, and the top surface of the return conveyor belt is cleaned by means of at least one peeling device.
超吸收劑用於製備尿布、棉塞、衛生棉及其他衛生用品，且亦用作市場園藝中之保水劑。超吸收劑亦被稱作吸水性聚合物。Superabsorbents are used to prepare diapers, tampons, sanitary napkins and other sanitary products, and are also used as water retention agents in market gardening. Superabsorbents are also called water-absorbing polymers.
超吸收劑之製備描述於專題著作「現代超吸收性聚合物技術(Modern Superabsorbent Polymer Technology)」, F. L. Buchholz及A. T. Graham, Wiley-VCH, 1998, 第71至103頁中。The preparation of superabsorbents is described in the monograph "Modern Superabsorbent Polymer Technology", F. L. Buchholz and A. T. Graham, Wiley-VCH, 1998, pages 71 to 103.
為改良效能特性，例如在49.2 g/cm² (AUL0.7psi)之壓力下之凝膠床滲透性(gel bed permeability；GBP)及吸收，超吸收性顆粒通常經表面後交聯。此增大顆粒表面之交聯水準，從而可至少部分地解耦在49.2 g/cm² (AUL0.7psi)之壓力下之吸收及離心保留容量(centrifuge retention capacity；CRC)。可在水性凝膠相中執行此表面後交聯。然而，較佳地，乾燥、研磨及篩分之聚合物顆粒(基質聚合物)用表面後交聯劑表面塗佈且經熱表面後交聯。適用於彼目的之交聯劑為可與聚合物顆粒之至少兩個羧酸根基團形成共價鍵之化合物。To improve performance characteristics, such as gel bed permeability (GBP) and absorption under a pressure of 49.2 g/cm² (AUL0.7psi), superabsorbent particles are usually post-crosslinked through the surface. This increases the level of cross-linking on the particle surface, which can at least partially decouple the absorption and centrifuge retention capacity (CRC) under a pressure of 49.2 g/cm² (AUL0.7psi). This surface post-crosslinking can be performed in the aqueous gel phase. However, preferably, the dried, ground, and sieved polymer particles (matrix polymer) are surface-coated with a surface post-crosslinking agent and cross-linked after the hot surface. Crosslinking agents suitable for this purpose are compounds that can form covalent bonds with at least two carboxylate groups of the polymer particles.
WO 2008/087114 A1、WO 2010/139680 A2及EP 2 700 667 A1描述藉助於振盪傳送帶使空氣循環帶式乾燥器之輸送帶裝載有水性聚合物凝膠。WO 2008/087114 A1, WO 2010/139680 A2 and
本發明之一目的為提供一種用於製備超吸收劑，尤其所使用之振盪傳送帶之更穩定操作的改良方法。An object of the present invention is to provide an improved method for preparing superabsorbents, especially for more stable operation of the oscillating conveyor belt used.
目的係利用藉由聚合包含以下之單體溶液或懸浮液來製備超吸收劑之方法來達成：
a) 至少一種烯系不飽和單體，其攜帶酸基且至少經部分中和，
b) 至少一種交聯劑及
c) 至少一種引發劑，
該方法包含對空氣循環帶式乾燥器中之所得水性聚合物凝膠進行乾燥、研磨、分類且視情況熱表面後交聯，其中該水性聚合物凝膠藉助於振盪傳送帶引入至該空氣循環帶式乾燥器中，且返回傳送帶之頂面藉助於至少一個剝離器件1來清潔。The purpose is to use a method of preparing a superabsorbent by polymerizing a monomer solution or suspension containing the following:
a) At least one ethylenically unsaturated monomer, which carries an acid group and is at least partially neutralized,
b) At least one crosslinking agent and
c) At least one initiator,
The method includes drying, grinding, sorting and optionally heating the surface and crosslinking the obtained aqueous polymer gel in an air circulating belt dryer, wherein the aqueous polymer gel is introduced into the air circulating belt by means of an oscillating conveyor belt In a type dryer, and the top surface of the returning conveyor belt is cleaned by means of at least one
振盪傳送帶為以豎直軸線可週期性地樞轉之傳送帶。振盪傳送帶之傳送帶自身基本上以恆定速度運行。振盪傳送帶之傳送帶具有比空氣循環帶式乾燥器之傳送帶明顯較小之寬度。振盪傳送帶之週期性樞轉運動導致在總寬度內空氣循環帶式乾燥器之傳送帶均勻覆蓋有聚合物凝膠。The oscillating conveyor belt is a conveyor belt that can be pivoted periodically with a vertical axis. The conveyor belt itself basically runs at a constant speed. The conveyor belt of the oscillating conveyor belt has a significantly smaller width than the conveyor belt of the air circulating belt dryer. The periodic pivoting movement of the oscillating conveyor belt causes the conveyor belt of the air circulating belt dryer to be uniformly covered with polymer gel in the total width.
返回傳送帶之頂面為傳送帶之內部，並不意欲與聚合物凝膠形成接觸。返回傳送帶之底面為傳送帶之外部，其在轉回之後接收另一經定量之量的聚合物凝膠。The top surface of the return conveyor belt is the inside of the conveyor belt and is not intended to come into contact with the polymer gel. The bottom surface of the returning conveyor belt is the outside of the conveyor belt, which receives another quantitative amount of polymer gel after being turned back.
剝離器件1與傳送帶之排出端的距離較佳為傳送帶長度之5%至45%、更佳地20%至40%、極佳地15%至30%，傳送帶之長度為樞轉軸與排出端之距離。The distance between the
與傳送帶接觸之剝離構件1之部分應比返回傳送帶之頂面更軟。適合之材料為天然或合成橡膠，諸如聚矽氧橡膠；聚醚醚酮(polyetheretherketone；PEEK)；鹵化聚烯烴，諸如聚氯乙烯(PVC)或聚四氟乙烯(PTFE)；聚醯胺(PA)；聚丙烯(PP)或聚乙烯(PE)。聚四氟乙烯(PTFE)為較佳的。The part of the
返回傳送帶之頂面上之剝離構件1可相對於傳送帶經預拉，使得剝離構件1與傳送帶具有良好接觸。若產生之力超出預拉力，則並非以剛性方式配置之剝離構件1可被迫遠離傳送帶。預拉力較佳為10至500 N，更佳地50至400 N，極其特別地100至300 N，且預拉力可借助於彈簧來設定。The
剝離構件1較佳地以與傳送帶之運行方向成直角自運行方向上傳送帶之中部至邊緣旋轉。此產生「V形」，其尖端指向傳送帶之運行方向。因此，將位於返回傳送帶之頂面上之聚合物凝膠經推送至傳送帶之邊緣且移除。內角較佳為130°至175°，更佳地140°至170°，極佳地150°至165°。剝離構件1之「V形」可為夾架(1)。The
圖1展示驅動/偏轉滾輪(3)之間的返回傳送帶(2)上之作為剝離構件1之夾架(1)。夾架(1)由例如不鏽鋼製成，且可栓固於振盪傳送帶之框架上。Figure 1 shows the clamping frame (1) as the
本發明係基於聚合物凝膠可進入傳送帶下方之發現。此聚合物凝膠隨後進入驅動滾筒或偏轉滾筒之滾筒表面上。聚合物凝膠導致滾筒表面上之帶未對準，意謂滾筒上之循環傳送帶移動至側面。此外，驅動滾筒之表面上之聚合物凝膠導致滾筒之滑脫，亦即導致驅動功率降低。聚合物凝膠藉助於剝離構件1可靠地移除。因此防止帶未對準及驅動滾筒之滑脫。The present invention is based on the discovery that polymer gel can enter under the conveyor belt. This polymer gel then enters the roller surface of the driving roller or the deflecting roller. The polymer gel causes the belt on the drum surface to be misaligned, which means that the endless conveyor belt on the drum moves to the side. In addition, the polymer gel on the surface of the driving drum causes the slippage of the drum, that is, the driving power is reduced. The polymer gel is reliably removed by means of the
在本發明之一個較佳實施例中，返回傳送帶之底面藉助於至少一個剝離器件2來清潔黏著之聚合物凝膠。In a preferred embodiment of the present invention, the bottom surface of the returning conveyor belt is cleaned of the adhered polymer gel by means of at least one
返回傳送帶之底面為傳送帶之外部，其在轉回之後接收另一經定量之量的聚合物凝膠。返回傳送帶之頂面為傳送帶之內部，並不意欲與聚合物凝膠形成接觸。The bottom surface of the returning conveyor belt is the outside of the conveyor belt, which receives another quantitative amount of polymer gel after being turned back. The top surface of the return conveyor belt is the inside of the conveyor belt and is not intended to come into contact with the polymer gel.
剝離器件2與傳送帶之排出端的距離較佳地小於傳送帶長度之20%，更佳地小於傳送帶長度之10%，極佳地小於傳送帶長度之5%，傳送帶之長度為樞轉軸與排出端之距離。The distance between the
剝離器件2並不經受任何限制。舉例而言，與運行方向橫向地配置之電刷為適合的。亦有可能使用刮除器。刮除器為與傳送方向橫向地配置且由非可撓性材料製成之剝離器件。適合之非可撓性材料之實例為聚四氟乙烯。為防止損壞傳送帶，刮除器應與傳送帶具有極小之直接接觸或沒有直接接觸。刮除器應相對於返回傳送帶之運行方向呈一傾角。此有助於黏著之聚合物凝膠剝落，且防止傳送帶與刮除器之間的堵塞。經剝離掉之聚合物凝膠通常掉落在空氣循環帶式乾燥器之傳送帶上。The
刮除器相對於傳送帶之運行方向的垂線較佳地傾斜5°至45°，更佳地10°至35°，極佳地15°至25°。刮除器與返回傳送帶之底面的距離較佳為0.1至5 mm，更佳地0.2至2 mm，極佳地0.5至1.5 mm。The scraper is preferably inclined 5° to 45° with respect to the vertical line of the running direction of the conveyor belt, more preferably 10° to 35°, and extremely preferably 15° to 25°. The distance between the scraper and the bottom surface of the return conveyor belt is preferably 0.1 to 5 mm, more preferably 0.2 to 2 mm, and extremely preferably 0.5 to 1.5 mm.
剝離器件1與傳送帶之樞轉軸的距離應小於剝離器件2與傳送帶之樞轉軸的距離。若藉助於剝離構件2移除之聚合物凝膠掉落在返回傳送帶之頂面上，則其可藉助於剝離構件1自返回傳送帶之頂面立即移除。The distance between the
剝離器件1與剝離器件2之間的距離較佳為傳送帶長度之至少5%、更佳地至少10%、極佳地至少15%，傳送帶之長度為樞轉軸與排出端之距離。The distance between the
傳送帶具有較佳地2至10 m、更佳地2.5至8 m、最佳地3至6 m之長度，傳送帶之長度為樞轉軸與排出端之距離。The conveyor belt has a length of preferably 2 to 10 m, more preferably 2.5 to 8 m, and most preferably 3 to 6 m. The length of the conveyor belt is the distance between the pivot axis and the discharge end.
傳送帶具有較佳地0.5至1.5 m、更佳地0.6至1.2 m、最佳地0.7至0.9 m之寬度。The conveyor belt has a width of preferably 0.5 to 1.5 m, more preferably 0.6 to 1.2 m, and most preferably 0.7 to 0.9 m.
傳送帶速度較佳為0.2至2.0 m/s，更佳地0.3至1.5 m/s，最佳地0.4至1.0 m/s。The speed of the conveyor belt is preferably 0.2 to 2.0 m/s, more preferably 0.3 to 1.5 m/s, most preferably 0.4 to 1.0 m/s.
出於此目的，有可能使用習用之傳送帶。傳送帶之表面(亦即與聚合物凝膠發生接觸之側面)應為防水的，且在23℃下具有較佳地至少60°、更佳地至少80°、最佳地至少100°之水接觸角。接觸角為潤濕行為之量測值且根據DIN 53900量測。For this purpose, it is possible to use conventional conveyor belts. The surface of the conveyor belt (that is, the side in contact with the polymer gel) should be waterproof and have a water contact of preferably at least 60°, more preferably at least 80°, and optimally at least 100° at 23°C angle. The contact angle is a measure of the wetting behavior and is measured according to DIN 53900.
傳送帶上之聚合物凝膠之含水量較佳為20至80重量%，更佳地30至70重量%，最佳地40至60重量%。The water content of the polymer gel on the conveyor belt is preferably 20 to 80% by weight, more preferably 30 to 70% by weight, and most preferably 40 to 60% by weight.
傳送帶上之聚合物凝膠之溫度較佳為60℃至105℃，更佳地70℃至100℃且最佳地80℃至95℃。The temperature of the polymer gel on the conveyor belt is preferably 60°C to 105°C, more preferably 70°C to 100°C, and most preferably 80°C to 95°C.
超吸收劑之製備詳細描述於下文中： 超吸收劑藉由聚合單體溶液或懸浮液來製備，且通常為不溶於水的。The preparation of superabsorbent is described in detail below: Superabsorbents are prepared by polymerizing monomer solutions or suspensions, and are generally insoluble in water.
單體a)較佳為水溶性的，亦即其於水中之溶解度在23℃下通常為至少1 g/100 g水，較佳地至少5 g/100 g水，更佳地至少25 g/100 g水且最佳地至少35 g/100 g水。Monomer a) is preferably water-soluble, that is, its solubility in water at 23°C is usually at least 1 g/100 g of water, preferably at least 5 g/100 g of water, more preferably at least 25 g/ 100 g water and optimally at least 35 g/100 g water.
適合之單體a)為例如烯系不飽和羧酸，諸如丙烯酸、甲基丙烯酸及伊康酸(itaconic acid)。尤佳單體為丙烯酸及甲基丙烯酸。極其較佳為丙烯酸。Suitable monomers a) are, for example, ethylenically unsaturated carboxylic acids, such as acrylic acid, methacrylic acid and itaconic acid. Particularly preferred monomers are acrylic acid and methacrylic acid. Very preferred is acrylic acid.
單體a)通常包含作為儲存穩定劑之聚合抑制劑，較佳地氫醌單醚。Monomer a) usually contains a polymerization inhibitor as a storage stabilizer, preferably hydroquinone monoether.
適合之交聯劑b)為具有適用於交聯之至少兩個基團之化合物。此類基團為例如可自由基聚合至聚合物鏈中之烯系不飽和基團及可與單體a)之酸基形成共價鍵之官能基。另外，可與單體a)之至少兩個酸基形成配位鍵之多價金屬鹽亦適用作交聯劑b)。Suitable crosslinking agents b) are compounds having at least two groups suitable for crosslinking. Such groups are, for example, ethylenically unsaturated groups that can be free-radically polymerized into the polymer chain and functional groups that can form covalent bonds with the acid groups of monomer a). In addition, polyvalent metal salts that can form coordinate bonds with at least two acid groups of monomer a) are also suitable as crosslinking agents b).
交聯劑b)較佳為具有可自由基聚合至聚合物網路中之至少兩個可聚合基團的化合物。適合之交聯劑b)為例如乙二醇二甲基丙烯酸酯、二乙二醇二丙烯酸酯、聚乙二醇二丙烯酸酯、甲基丙烯酸烯丙酯、三羥甲基丙烷三丙烯酸酯、三烯丙基胺、氯化四烯丙銨、四烯丙氧基乙烷，如EP 0 530 438 A1中所描述；二丙烯酸酯及三丙烯酸酯(如EP 0 547 847 A1、EP 0 559 476 A1、EP 0 632 068 A1、WO 93/21237 A1、WO 03/104299 A1、WO 03/104300 A1、WO 03/104301 A1及DE 103 31 450 A1中所描述)、其混合丙烯酸酯；以及丙烯酸酯基；包含其他烯系不飽和基團(如DE 103 31 456 A1及DE 103 55 401 A1中所描述)；或交聯劑混合物，如例如DE 195 43 368 A1、DE 196 46 484 A1、WO 90/15830 A1及WO 02/032962 A2中所描述。The crosslinking agent b) is preferably a compound having at least two polymerizable groups that can be free-radically polymerized into the polymer network. Suitable crosslinking agents b) are, for example, ethylene glycol dimethacrylate, diethylene glycol diacrylate, polyethylene glycol diacrylate, allyl methacrylate, trimethylolpropane triacrylate, Triallylamine, tetraallylammonium chloride, tetraallyloxyethane, as described in EP 0 530 438 A1; diacrylate and triacrylate (such as EP 0 547 847 A1, EP 0 559 476 A1, EP 0 632 068 A1, WO 93/21237 A1, WO 03/104299 A1, WO 03/104300 A1, WO 03/104301 A1 and DE 103 31 450 A1), mixed acrylates thereof; and acrylates Group; containing other ethylenically unsaturated groups (as described in DE 103 31 456 A1 and DE 103 55 401 A1); or crosslinking agent mixtures, such as, for example, DE 195 43 368 A1, DE 196 46 484 A1, WO 90 /15830 A1 and WO 02/032962 A2.
交聯劑b)之量較佳為0.05重量%至1.5重量%，更佳地0.1重量%至1重量%且最佳地0.3重量%至0.6重量% (在各情況下基於所使用之單體a)之總量來計算)。隨著交聯劑含量上升，離心保留容量(CRC)下降且在21.0 g/cm² (AUL0.3psi)之壓力下之吸收達至最大值。The amount of crosslinking agent b) is preferably 0.05% to 1.5% by weight, more preferably 0.1% to 1% by weight, and most preferably 0.3% to 0.6% by weight (in each case based on the monomer used a) to calculate the total amount). As the content of crosslinking agent increases, the centrifuge retention capacity (CRC) decreases and the absorption reaches its maximum value under a pressure of 21.0 g/cm² (AUL0.3psi).
所使用之引發劑c)可為在聚合條件下產生自由基之所有化合物，例如熱引發劑、氧化還原引發劑或光引發劑。適合之氧化還原引發劑為過硫酸鈉/抗壞血酸、過氧化氫/抗壞血酸、過硫酸鈉/亞硫酸氫鈉及過氧化氫/亞硫酸氫鈉。較佳為使用熱引發劑及氧化還原引發劑之混合物，諸如過硫酸鈉/過氧化氫/抗壞血酸。所使用之還原組分較佳為2-羥基-2-磺酸基乙酸之二鈉鹽或2-羥基-2-亞磺酸基乙酸之鈉鹽、2-羥基-2-磺酸基乙酸之二鈉鹽及亞硫酸氫鈉的混合物。此類混合物可以Brüggolite® FF6及Brüggolite® FF7 (Brüggemann Chemicals；Heilbronn；德國)形式獲得。The initiator c) used can be all compounds that generate free radicals under polymerization conditions, such as thermal initiators, redox initiators or photoinitiators. Suitable redox initiators are sodium persulfate/ascorbic acid, hydrogen peroxide/ascorbic acid, sodium persulfate/sodium bisulfite and hydrogen peroxide/sodium bisulfite. It is preferable to use a mixture of a thermal initiator and a redox initiator, such as sodium persulfate/hydrogen peroxide/ascorbic acid. The reducing component used is preferably the disodium salt of 2-hydroxy-2-sulfoacetic acid or the sodium salt of 2-hydroxy-2-sulfinoacetic acid, or the sodium salt of 2-hydroxy-2-sulfoacetic acid. A mixture of disodium salt and sodium bisulfite. Such mixtures are available in the form of Brüggolite® FF6 and Brüggolite® FF7 (Brüggemann Chemicals; Heilbronn; Germany).
通常，使用單體水溶液。單體溶液之含水量較佳為40重量%至75重量%，更佳地45重量%至70重量%且最佳地50重量%至65重量%。亦有可能使用單體懸浮液，亦即溶解度超過單體a)之單體溶液，例如丙烯酸鈉。當含水量上升時，後續乾燥中之能量消耗上升，且當含水量下降時，僅可不充分地移除聚合熱。Generally, an aqueous monomer solution is used. The water content of the monomer solution is preferably 40% to 75% by weight, more preferably 45% to 70% by weight, and most preferably 50% to 65% by weight. It is also possible to use monomer suspensions, that is, monomer solutions with a solubility exceeding monomer a), such as sodium acrylate. When the water content increases, the energy consumption in the subsequent drying increases, and when the water content decreases, the heat of polymerization can only be insufficiently removed.
對於最佳作用，較佳的聚合抑制劑需要溶解氧。因此，單體溶液可在聚合之前藉由惰性化，亦即使惰性氣體(較佳地氮氣或二氧化碳)流過來釋放溶解氧。單體溶液之氧含量在聚合之前較佳地下降至小於1重量ppm，更佳地小於0.5重量ppm，最佳地小於0.1重量ppm。For optimal effect, the preferred polymerization inhibitors require dissolved oxygen. Therefore, the monomer solution can be inertized before polymerization, even if an inert gas (preferably nitrogen or carbon dioxide) flows over to release dissolved oxygen. The oxygen content of the monomer solution is preferably reduced to less than 1 ppm by weight before polymerization, more preferably less than 0.5 ppm by weight, and most preferably less than 0.1 ppm by weight.
用於聚合之適合反應器為例如捏合反應器或帶式反應器。如WO 2001/038402 A1中所描述，在捏合機中，單體水溶液或懸浮液之聚合中所形成之聚合物凝膠藉由例如反向旋轉攪拌器軸(contrarotatory stirrer shaft)連續地粉碎。帶上之聚合描述於例如DE 38 25 366 A1及US 6,241,928中。帶式反應器中之聚合形成必須在例如擠壓機或捏合機中粉碎之聚合物凝膠。Suitable reactors for polymerization are, for example, kneading reactors or belt reactors. As described in WO 2001/038402 A1, in the kneader, the polymer gel formed in the polymerization of the monomer aqueous solution or suspension is continuously pulverized by, for example, a contrarotatory stirrer shaft. Polymerization on the tape is described in, for example, DE 38 25 366 A1 and US 6,241,928. Polymerization in a belt reactor forms a polymer gel that must be comminuted in, for example, an extruder or kneader.
為改良乾燥特性，可額外擠壓藉助於捏合機獲得之經粉碎聚合物凝膠。In order to improve the drying characteristics, the pulverized polymer gel obtained by means of a kneader can be additionally extruded.
所得聚合物凝膠之酸基通常經部分中和。較佳在單體階段地實行中和。此通常藉由混合呈水溶液形式或另外較佳地呈固體形式之中和劑來實行。中和度較佳為40至85 mol%，更佳地50至80 mol%且最佳地60至75 mol%，其中可使用習用中和劑，較佳地鹼金屬氫氧化物、鹼金屬氧化物、鹼金屬碳酸鹽或鹼金屬碳酸氫鹽以及其混合物。亦有可能使用銨鹽而非鹼金屬鹽。尤佳的鹼金屬為鈉及鉀，但極其較佳為氫氧化鈉、碳酸鈉或碳酸氫鈉以及其混合物。固態碳酸鹽及碳酸氫鹽亦可以囊封形式引入於此，較佳地在聚合之前直接地引入至單體溶液中，在聚合期間或之後且在其乾燥之前引入至聚合物凝膠中。囊封藉由用不溶或僅逐漸溶解之材料塗佈表面(例如，藉助於成膜聚合物、惰性無機材料或可熔性有機材料)來實現，該材料將固態碳酸鹽或碳酸氫鹽之溶解及反應延遲至不釋放二氧化碳之此類程度直至乾燥過程為止，且所形成之超吸收劑具有較高內部孔隙率。The acid groups of the resulting polymer gel are usually partially neutralized. The neutralization is preferably carried out in the monomer stage. This is usually carried out by mixing the neutralizing agent in the form of an aqueous solution or otherwise preferably in the form of a solid. The degree of neutralization is preferably 40 to 85 mol%, more preferably 50 to 80 mol% and most preferably 60 to 75 mol%. Among them, conventional neutralizing agents can be used, preferably alkali metal hydroxides, alkali metal oxidation , Alkali metal carbonate or alkali metal bicarbonate and mixtures thereof. It is also possible to use ammonium salts instead of alkali metal salts. Particularly preferred alkali metals are sodium and potassium, but extremely preferred are sodium hydroxide, sodium carbonate or sodium bicarbonate and mixtures thereof. Solid carbonate and bicarbonate can also be introduced here in encapsulated form, preferably directly into the monomer solution before polymerization, and into the polymer gel during or after polymerization and before drying. Encapsulation is achieved by coating the surface with an insoluble or only gradually dissolving material (for example, with the aid of film-forming polymers, inert inorganic materials or fusible organic materials) that dissolves solid carbonate or bicarbonate And the reaction is delayed to such an extent that no carbon dioxide is released until the drying process, and the superabsorbent formed has a higher internal porosity.
聚合物凝膠隨後通常經空氣循環帶式乾燥器乾燥直至殘餘水分含量較佳為0.5至10重量%，更佳地1至7重量%且最佳地2至5重量%為止，殘餘水分含量藉由EDANA建議之測試方法第WSP 230.2-05號「加熱後之質量損失(Mass Loss Upon Heating)」來測定。在殘餘水分含量太高之情況下，經乾燥之聚合物凝膠具有太低之玻璃轉變溫度Tg 且僅可困難地進一步處理。在殘餘水分含量太低之情況下，經乾燥之聚合物凝膠太脆，且在後續粉碎步驟中，獲得不合需要地大量具有過低粒度之聚合物顆粒(「細粒」)。在乾燥之前聚合物凝膠之固體含量較佳為25重量%至90重量%，更佳地35重量%至70重量%，最佳地40重量%至60重量%。隨後，經乾燥之聚合物凝膠經壓碎且視情況粗略地粉碎。The polymer gel is then usually dried by an air circulating belt dryer until the residual moisture content is preferably 0.5 to 10% by weight, more preferably 1 to 7% by weight, and most preferably 2 to 5% by weight, the residual moisture content is determined by It is determined by the test method No. WSP 230.2-05 "Mass Loss Upon Heating" recommended by EDANA. In the case of too high residual moisture content, the dried polymer gel has a glass transition temperature T g that is too low and can only be processed further with difficulty. In the case where the residual moisture content is too low, the dried polymer gel is too brittle, and in the subsequent pulverization step, an undesirably large amount of polymer particles ("fine particles") with too low particle size are obtained. The solid content of the polymer gel before drying is preferably 25% to 90% by weight, more preferably 35% to 70% by weight, most preferably 40% to 60% by weight. Subsequently, the dried polymer gel is crushed and roughly pulverized as appropriate.
其後，通常對經乾燥之聚合物凝膠進行研磨及分類，且用於研磨之裝置可通常為單級或多級輥磨機，較佳地二級或三級輥磨機、針磨機、錘磨機或振動球磨機。After that, the dried polymer gel is usually ground and classified, and the device for grinding can usually be a single-stage or multi-stage roller mill, preferably a two-stage or three-stage roller mill, a pin mill , Hammer mill or vibrating ball mill.
作為產物級分移除之聚合物顆粒之平均粒度較佳為150至850 µm，更佳地250至600 µm，極其特定地300至500 µm。產物級分之平均粒度可藉助於EDANA建議之測試方法第WSP 220.2 (05)號「粒度分佈(Particle Size Distribution)」來測定，其中以篩檢級分之質量計之比例以累積形式繪製且平均粒度以圖形方式判定。此處之平均粒度為產生累積50重量%之篩孔尺寸之值。The average particle size of the polymer particles removed as the product fraction is preferably 150 to 850 µm, more preferably 250 to 600 µm, and very specifically 300 to 500 µm. The average particle size of the product fraction can be determined by means of the test method No. WSP 220.2 (05) "Particle Size Distribution" recommended by EDANA, in which the ratio of the mass of the screening fraction is plotted in cumulative form and averaged The granularity is determined graphically. The average particle size here is the value of the mesh size that produces a cumulative 50% by weight.
為進一步改良特性，聚合物顆粒可經熱表面後交聯。適合之表面後交聯劑為包含可與聚合物顆粒之至少兩個羧酸根基團形成共價鍵的基團之化合物。適合之化合物為例如多官能胺，多官能醯胺基胺、多官能環氧化物，如EP 0 083 022 A2、EP 0 543 303 A1及EP 0 937 736 A2中所描述；二官能醇或多官能醇，如DE 33 14 019 A1、DE 35 23 617 A1及EP 0 450 922 A2中所描述；或β-羥烷基醯胺，如DE 102 04 938 A1及US 6,239,230中所描述。To further improve the properties, the polymer particles can be cross-linked after being heated to the surface. Suitable surface post-crosslinking agents are compounds containing groups that can form covalent bonds with at least two carboxylate groups of the polymer particles. Suitable compounds are, for example, polyfunctional amines, polyfunctional amidoamines, polyfunctional epoxides, as described in EP 0 083 022 A2, EP 0 543 303 A1 and EP 0 937 736 A2; difunctional alcohols or polyfunctional Alcohols, as described in DE 33 14 019 A1, DE 35 23 617 A1 and EP 0 450 922 A2; or β-hydroxyalkylamides, as described in DE 102 04 938 A1 and US 6,239,230.
在各情況下按聚合物顆粒計，表面後交聯劑之量較佳為0.001重量%至2重量%，更佳地0.02重量%至1重量%且最佳地0.05重量%至0.2重量%。In each case, based on the polymer particles, the amount of the surface post-crosslinking agent is preferably 0.001% to 2% by weight, more preferably 0.02% to 1% by weight, and most preferably 0.05% to 0.2% by weight.
在本發明之一較佳實施例中，除表面後交聯劑以外，將多價陽離子施用於顆粒表面。In a preferred embodiment of the present invention, in addition to the surface post-crosslinking agent, a multivalent cation is applied to the surface of the particle.
可用於本發明之方法中之多價陽離子為例如二價陽離子，諸如鋅、鎂、鈣及鍶之陽離子；三價陽離子，諸如鋁、鐵、鉻、稀土及錳之陽離子；四價陽離子，諸如鈦及鋯之陽離子。可能的相對離子為氯離子、溴離子、氫氧根、硫酸根、硫酸氫根、碳酸根、碳酸氫根、硝酸根、磷酸根、磷酸氫根、二氫磷酸根及羧酸根，諸如乙酸根及乳酸根。氫氧化鋁、硫酸鋁及乳酸鋁為較佳的。Multivalent cations that can be used in the method of the present invention are, for example, divalent cations, such as zinc, magnesium, calcium, and strontium; trivalent cations, such as aluminum, iron, chromium, rare earth and manganese cations; and tetravalent cations, such as Cation of titanium and zirconium. Possible counter ions are chloride, bromide, hydroxide, sulfate, hydrogen sulfate, carbonate, hydrogen carbonate, nitrate, phosphate, hydrogen phosphate, dihydrophosphate and carboxylate, such as acetate And lactate. Aluminum hydroxide, aluminum sulfate and aluminum lactate are preferred.
在各情況下按聚合物計，所使用之多價陽離子之量為例如0.001重量%至1.5重量%，較佳地0.005重量%至1重量%且更佳地0.02重量%至0.8重量%。In each case, based on the polymer, the amount of the polyvalent cation used is, for example, 0.001% to 1.5% by weight, preferably 0.005% to 1% by weight, and more preferably 0.02% to 0.8% by weight.
表面後交聯通常以將表面後交聯劑之溶液噴霧至經乾燥之聚合物顆粒上之此方式執行。在噴霧施加之後，塗佈有表面後交聯劑之聚合物顆粒經表面後交聯及乾燥，且可在乾燥之前及乾燥期間均發生表面後交聯反應。Surface post-crosslinking is usually performed by spraying a solution of the surface post-crosslinking agent onto the dried polymer particles. After spray application, the polymer particles coated with the surface post-crosslinking agent are surface post-crosslinked and dried, and the surface post-crosslinking reaction can occur before and during drying.
表面後交聯劑之溶液之噴霧施加較佳地於具有移動混合工具之混合器(諸如螺桿混合器、圓盤式混合器及槳葉式混合器)執行。尤其較佳為臥式混合器(諸如槳葉式混合器)，極其較佳的為立式混合器。臥式混合器與立式混合器之間的區別在於混合軸之位置，亦即臥式混合器具有水平安裝之混合軸且立式混合器具有豎直安裝之混合軸。適合之混合器為例如臥式Pflugschar®犁鏵式混合器(plowshare mixer) (Gebr. Lödige Maschinenbau GmbH；Paderborn；德國)、Vrieco-Nauta連續混合器(Hosokawa Micron BV；Doetinchem；荷蘭)、Processall Mixmill混合器(Processall Incorporated；Cincinnati；美國)及Schugi Flexomix® (Hosokawa Micron BV；Doetinchem；荷蘭)。然而，亦有可能在流體化床中噴霧表面後交聯劑溶液。The spray application of the solution of the surface post-crosslinking agent is preferably performed in a mixer with a moving mixing tool (such as a screw mixer, a disc mixer, and a paddle mixer). Especially preferred is a horizontal mixer (such as a paddle mixer), and extremely preferred is a vertical mixer. The difference between the horizontal mixer and the vertical mixer is the position of the mixing shaft, that is, the horizontal mixer has a horizontally installed mixing shaft and the vertical mixer has a vertically installed mixing shaft. Suitable mixers are, for example, horizontal Pflugschar® plowshare mixer (Gebr. Lödige Maschinenbau GmbH; Paderborn; Germany), Vrieco-Nauta continuous mixer (Hosokawa Micron BV; Doetinchem; Netherlands), Processall Mixmill mixer (Processall Incorporated; Cincinnati; USA) and Schugi Flexomix® (Hosokawa Micron BV; Doetinchem; Netherlands). However, it is also possible to spray the surface post-crosslinker solution in a fluidized bed.
表面後交聯劑通常以水溶液之形式使用。表面後交聯劑至聚合物顆粒中之穿透深度(penetration depth)可經由非水性溶劑之含量及溶劑之總量來調整。The surface post-crosslinking agent is usually used in the form of an aqueous solution. The penetration depth of the surface post-crosslinking agent into the polymer particles can be adjusted by the content of the non-aqueous solvent and the total amount of the solvent.
表面後交聯較佳地於接觸式乾燥器、更佳地鏟式乾燥器、最佳地圓盤式乾燥器中執行。適合之乾燥器為例如Hosokawa Bepex®水平槳葉式乾燥器(Horizontal Paddle Dryer) (Hosokawa Micron GmbH；Leingarten；德國)、Hosokawa Bepex®碟式乾燥器(Hosokawa Micron GmbH；Leingarten；德國)、Holo-Flite®乾燥器(Metso Minerals Industries Inc.；Danville；美國)及Nara槳葉式乾燥器(NARA Machinery Europe；Frechen；德國)。此外，亦可使用流體化床乾燥器。Surface post-crosslinking is preferably performed in contact dryers, more preferably shovel dryers, and best disc dryers. Suitable dryers are, for example, Hosokawa Bepex® Horizontal Paddle Dryer (Hosokawa Micron GmbH; Leingarten; Germany), Hosokawa Bepex® Dish Dryer (Hosokawa Micron GmbH; Leingarten; Germany), Holo-Flite ® Dryer (Metso Minerals Industries Inc.; Danville; USA) and Nara paddle dryer (NARA Machinery Europe; Frechen; Germany). In addition, fluidized bed dryers can also be used.
表面後交聯可藉由加熱護套或吹入暖氣於混合器自身中來實行。同樣適合的為下游乾燥器(downstream dryer)，例如箱形乾燥器、旋轉管式烘箱或可加熱螺桿。尤其有利於在流體化床乾燥器中實行混合及熱表面後交聯。The post-crosslinking of the surface can be performed by heating the jacket or blowing heating into the mixer itself. Also suitable are downstream dryers, such as box dryers, rotary tube ovens or heatable screws. It is especially beneficial for mixing and crosslinking after hot surface in a fluidized bed dryer.
較佳的反應溫度在100℃至250℃、較佳地110℃至220℃、更佳地120℃至210℃、最佳地130℃至200℃之範圍內。此溫度下之較佳停留時間較佳為至少10分鐘，更佳地至少20分鐘，最佳地至少30分鐘，且通常至多60分鐘。The preferred reaction temperature is in the range of 100°C to 250°C, preferably 110°C to 220°C, more preferably 120°C to 210°C, and most preferably 130°C to 200°C. The preferred residence time at this temperature is preferably at least 10 minutes, more preferably at least 20 minutes, most preferably at least 30 minutes, and usually at most 60 minutes.
隨後，可再次分類經表面後交聯之聚合物顆粒，其中將過小及/或過大的聚合物顆粒移除且再循環至方法中。Subsequently, the surface-post-crosslinked polymer particles can be sorted again, in which polymer particles that are too small and/or too large are removed and recycled to the process.
為進一步改良特性，可塗佈或再潤濕經表面後交聯之聚合物顆粒。To further improve the properties, the polymer particles that have been cross-linked after the surface can be coated or rewet.
再潤濕較佳地在30℃至80℃下，更佳地在35℃至70℃下，最佳地在40℃至60℃下執行。在過低溫度下，聚合物顆粒趨向於形成結塊，且在較高溫度下，水已經蒸發至可辨程度。用於再潤濕之水量較佳為1重量%至10重量%，更佳地2重量%至8重量%且最佳地3重量%至5重量%。再潤濕增大聚合物顆粒之機械穩定性且降低其靜態充電之傾向。在熱表面後交聯之後，再潤濕有利地於冷卻器中執行。The rewetting is preferably performed at 30°C to 80°C, more preferably 35°C to 70°C, and most preferably 40°C to 60°C. At too low temperatures, polymer particles tend to form agglomerates, and at higher temperatures, the water has evaporated to a discernible degree. The amount of water used for re-wetting is preferably 1% to 10% by weight, more preferably 2% to 8% by weight, and most preferably 3% to 5% by weight. Rewetting increases the mechanical stability of polymer particles and reduces their tendency to static charge. After the hot surface is post-crosslinked, rewetting is advantageously performed in the cooler.
用於改良自由膨脹速率及凝膠床滲透性(GBP)之適合塗料為例如無機惰性物質，諸如不溶於水的金屬鹽；有機聚合物；陽離子聚合物及二價或多價金屬陽離子。用於灰塵結合之適合塗料為例如多元醇。用於抵抗聚合物顆粒之非所需結塊傾向之適合塗料為例如煙霧狀二氧化矽，諸如Aerosil® 200；經沈澱矽石，諸如Sipernat® D17；及界面活性劑，諸如Span® 20。Suitable coatings for improving the free expansion rate and gel bed permeability (GBP) are, for example, inorganic inert substances such as water-insoluble metal salts; organic polymers; cationic polymers and divalent or multivalent metal cations. Suitable coatings for dust binding are, for example, polyols. Suitable coatings for resisting the undesired tendency of polymer particles to agglomerate are, for example, fumed silica, such as Aerosil® 200; precipitated silica, such as Sipernat® D17; and surfactants, such as Span® 20.
本發明進一步提供包含由本發明之方法製備之超吸收劑的衛生用品。The present invention further provides sanitary products containing the superabsorbent prepared by the method of the present invention.
方法： 下文中所描述及「WSP」所特指之標準測試方法描述於以下中：由Worldwide Strategic Partners EDANA (Herrmann-Debrouxlaan 46, 1160 Oudergem, Belgium, www.edana.org)及INDA (1100 Crescent Green, Suite 115, Cary, North Carolina 27518, 美國, www.inda.org)聯合公開之「Standard Test Methods for the Nonwovens Industry」, 2005版。此公開案可自EDANA及INDA二者獲得。method: The standard test methods described below and specified by "WSP" are described in the following: Worldwide Strategic Partners EDANA (Herrmann-Debrouxlaan 46, 1160 Oudergem, Belgium, www.edana.org) and INDA (1100 Crescent Green, Suite 115, Cary, North Carolina 27518, USA, www.inda.org) "Standard Test Methods for the Nonwovens Industry", 2005 edition published jointly. This public case is available from both EDANA and INDA.
除非另外陳述，否則量測應在23±2℃之環境溫度及50±10%之相對空氣濕度下進行。吸水性聚合物顆粒在量測之前經充分地混合。Unless otherwise stated, the measurement should be performed at an ambient temperature of 23±2°C and a relative humidity of 50±10%. The water-absorbing polymer particles are thoroughly mixed before the measurement.
離心保留容量 離心保留容量(CRC)藉由EDANA建議之測試方法第WSP 241.2 (05)號「離心後鹽水中之流體保留容量(Fluid Retention Capacity in Saline, After Centrifugation)」來測定。Centrifugal retention capacity The centrifugal retention capacity (CRC) is determined by the test method No. WSP 241.2 (05) recommended by EDANA "Fluid Retention Capacity in Saline (After Centrifugation)".
可萃取物 吸水性聚合物顆粒之可萃取物之含量藉由EDANA建議之測試方法第WSP 270.2 (05)號「可萃取(Extractable)」來測定。Extractables The extractable content of the water-absorbent polymer particles is determined by the test method No. WSP 270.2 (05) "Extractable" recommended by EDANA.
實例 藉由連續地混合去離子水、50重量%之氫氧化鈉溶液及丙烯酸，丙烯酸/丙烯酸鈉溶液經製備以使得中和度對應於71.3 mol%。單體溶液之固體含量為38.8重量%。Instance By continuously mixing deionized water, 50% by weight sodium hydroxide solution, and acrylic acid, the acrylic acid/sodium acrylate solution was prepared so that the degree of neutralization corresponds to 71.3 mol%. The solid content of the monomer solution was 38.8% by weight.
所使用之聚烯系不飽和交聯劑為聚乙二醇-400二丙烯酸酯(二丙烯酸酯由具有400 g/mol之平均莫耳質量之聚乙二醇進行製備)。所使用之量為每t單體溶液2 kg交聯劑。The polyethylenically unsaturated crosslinking agent used is polyethylene glycol-400 diacrylate (diacrylate is prepared from polyethylene glycol with an average molar mass of 400 g/mol). The amount used is 2 kg of crosslinker per t monomer solution.
為引發自由基聚合，每t單體溶液使用1.03 kg之0.25重量%過氧化氫水溶液、3.10 kg之15重量%過二硫酸鈉水溶液及1.05 kg之1重量%抗壞血酸水溶液。To initiate free radical polymerization, 1.03 kg of 0.25% by weight aqueous hydrogen peroxide solution, 3.10 kg of 15% by weight sodium peroxodisulfate aqueous solution and 1.05 kg of 1% by weight ascorbic acid aqueous solution were used per t monomer solution.
單體溶液之輸送量為20 t/h。反應溶液具有23.5℃之饋入溫度。The throughput of the monomer solution is 20 t/h. The reaction solution has a feeding temperature of 23.5°C.
個別組分以以下量連續地定量至具有6.3 m³之容量的List Contikneter連續捏合機反應器(LIST AG，Arisdorf，Switzerland)中： 20 t/h 單體溶液 40 kg/h 聚乙二醇-400二丙烯酸酯 82.6 kg/h 過氧化氫溶液/過二硫酸鈉溶液 21 kg/h 抗壞血酸溶液The individual components are continuously quantified in the following quantities into the List Contikneter continuous kneader reactor (LIST AG, Arisdorf, Switzerland) with a capacity of 6.3 m³: 20 t/h Monomer solution 40 kg/h Polyethylene glycol-400 diacrylate 82.6 kg/h hydrogen peroxide solution/sodium peroxodisulfate solution 21 kg/h Ascorbic acid solution
在交聯劑之添加點與引發劑之添加位點之間，單體溶液用氮氣惰性化。Between the point of addition of the crosslinking agent and the point of addition of the initiator, the monomer solution is inertized with nitrogen.
在約50%之滯留時間之後，藉由研磨及篩分自製備方法獲得的細粒額外定量的添加(1000 kg/h)至反應器中。反應混合物於反應器中之停留時間為15分鐘。After a residence time of about 50%, the fine particles obtained from the preparation method by grinding and sieving are additionally quantitatively added (1000 kg/h) to the reactor. The residence time of the reaction mixture in the reactor is 15 minutes.
所獲得之水性聚合物凝膠藉助於振盪傳送帶施加於空氣循環帶式乾燥器之傳送帶。The obtained aqueous polymer gel is applied to the conveyor belt of the air circulating belt dryer by means of an oscillating conveyor belt.
空氣循環帶式乾燥器具有48 m之長度。空氣循環帶式乾燥器之傳送帶具有4.4 m之有效寬度。The air circulation belt dryer has a length of 48 m. The conveyor belt of the air circulation belt dryer has an effective width of 4.4 m.
振盪傳送帶具有5 m之長度。傳送帶具有0.8 m之寬度及0.5 m之有效寬度。水性聚合物凝膠於傳送帶上之靜止角為約15°。聚合物凝膠床於傳送帶上之橫截面為約0.04 m²。傳送帶之速度為0.5 m/s。The oscillating conveyor belt has a length of 5 m. The conveyor belt has a width of 0.8 m and an effective width of 0.5 m. The angle of repose of the aqueous polymer gel on the conveyor belt is about 15°. The cross section of the polymer gel bed on the conveyor belt is about 0.04 m². The speed of the conveyor belt is 0.5 m/s.
自一端位置行進，振盪傳送帶經由13°之第一樞轉角β1 加速至33°/s之角速度，經由20°之第二樞轉角β2 減速至17°/s之角速度且經由第三樞轉角β3 減速至另一端位置。總樞轉角為50°。雙程(自第一端位置至另一端位置且返回)持續約7 s。循環傳送帶具有聚四氟乙烯(PTFE)之表面。Moving from one end position, the oscillating conveyor is accelerated to an angular velocity of 33°/s through a first pivot angle β 1 of 13°, decelerated to an angular velocity of 17°/s through a second pivot angle β 2 of 20°, and passes through a third pivot angle β 3 decelerates to the other end position. The total pivot angle is 50°. The round trip (from the first end position to the other end position and back) lasts about 7 s. The endless conveyor belt has a surface of polytetrafluoroethylene (PTFE).
振盪傳送帶上之水性聚合物凝膠之溫度為90℃。The temperature of the aqueous polymer gel on the oscillating conveyor belt is 90°C.
如圖1中所展示，剝離構件1安裝於返回傳送帶之頂面上。剝離器件1與排出端之距離為約1 m。所使用之剝離構件1為由不鏽鋼製成之夾架(1)。與傳送帶接觸之夾架(1)之部分由聚四氟乙烯製成且具有約5 mm之厚度。夾架(1)之前拐角上之內角為約160°。將夾架(1)栓固至振盪傳送帶之框架且藉助於彈簧按壓至傳送帶上。As shown in Fig. 1, the peeling
剝離器件2位於振盪傳送帶之底面上。剝離器件2為與返回傳送帶之運行方向橫向地安裝之細長刮除器。刮除器相對於返回傳送帶之運行方向具有20°之傾角。剝離器件2與排出端之距離為約5 cm，亦即剝離構件2位於偏轉滾輪之區域中。剝離器件2與返回傳送帶之距離為1 mm。剝離器件2剝離掉黏著於返回傳送帶之外部上之水性聚合物凝膠。The
循環傳送帶之操作不困難。剝離構件1防止掉落在返回傳送帶之頂面上之聚合物凝膠進入滾筒與傳送帶之間。The operation of the circulating conveyor belt is not difficult. The peeling
在空氣循環帶式乾燥器上，空氣/氣體混合物圍繞水性聚合物凝膠連續地流動且使其乾燥。空氣循環帶式乾燥器中之滯留時間為37分鐘。On the air circulation belt dryer, the air/gas mixture continuously flows around the aqueous polymer gel and dries it. The residence time in the air circulating belt dryer is 37 minutes.
將經乾燥之聚合物凝膠研磨且篩分至150至850 µm之粒度級分。The dried polymer gel is ground and sieved to a particle size fraction of 150 to 850 µm.
所得吸水性聚合物顆粒具有34.9 g/g之離心保留容量(CRC)及8.5重量%之可萃取物含量。The obtained water-absorbing polymer particles have a centrifuge retention capacity (CRC) of 34.9 g/g and an extractable content of 8.5% by weight.
1:夾架 2:返回傳送帶 3:驅動/偏轉滾輪1: Clip frame 2: Return to the conveyor belt 3: drive/deflection roller
圖1展示驅動/偏轉滾輪(3)之間的返回傳送帶(2)上之作為剝離構件1之夾架(1)。Figure 1 shows the clamping frame (1) as the peeling
1:夾架 1: Clip frame
2:返回傳送帶 2: Return to the conveyor belt
3:驅動/偏轉滾輪 3: drive/deflection roller
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