阅读说明：本技术 一种耐酸离子交换膜片及其制备方法 (Acid-resistant ion exchange membrane and preparation method thereof ) 是由 吕大为 于 2020-04-11 设计创作，主要内容包括：本发明涉及隔膜材料领域,具体涉及一种耐酸离子交换膜片及其制备方法,解决了传统离子交换膜片耐酸腐蚀性能差的问题。其中,一种耐酸离子交换膜片,以重量份数计,包括如下组分：离子交换树脂粉末5000-6000份、改性线性低密度聚乙烯3000-4000份以及聚乙烯蜡50-80份；所述改性线性低密度聚乙烯由纳米二氧化硅、海泡石粉、微晶纤维素以及硅烷偶联剂对线性低密度聚乙烯改性而成；线性低密度聚乙烯的熔融指数为2.0g/10min,密度为0.9225g/cm<Sup>3</Sup>。本发明提供的耐酸离子交换膜片具有耐酸腐蚀性能好、离子交换性能佳、使用寿命长的效果。(The invention relates to the field of diaphragm materials, in particular to an acid-resistant ion exchange diaphragm and a preparation method thereof, and solves the problem of poor acid corrosion resistance of the traditional ion exchange diaphragm. The acid-resistant ion exchange membrane comprises the following components in parts by weight: 6000 parts of ion exchange resin powder 5000-; the modified linear low-density polyethylene is prepared by modifying linear low-density polyethylene by nano silicon dioxide, sepiolite powder, microcrystalline cellulose and a silane coupling agent; melting of linear low density polyethyleneThe index is 2.0g/10min, and the density is 0.9225g/cm 3 . The acid-resistant ion exchange membrane provided by the invention has the effects of good acid corrosion resistance, good ion exchange performance and long service life.)

1. An acid-resistant ion exchange membrane characterized by: the paint comprises the following components in parts by weight:

6000 parts of ion exchange resin powder 5000-;

the modified linear low-density polyethylene is prepared by modifying linear low-density polyethylene by nano silicon dioxide, sepiolite powder, microcrystalline cellulose and a silane coupling agent;

the linear low density polyethylene has a melt index of 2.0g/10min and a density of 0.9225g/cm³。

2. The acid-resistant ion exchange membrane of claim 1, wherein: the ion exchange resin powder comprises cation exchange resin powder and anion exchange resin powder; the cation exchange resin powder is styrene sulfonic acid type cation exchange resin, and the anion exchange resin powder is styrene quaternary ammonium type anion exchange resin.

3. The acid-resistant ion exchange membrane of claim 1, wherein the modified linear low density polyethylene is prepared by mixing ① parts by weight of nano silicon dioxide 15-20 parts, sepiolite powder 3-7 parts and microcrystalline cellulose 1 part to obtain a blend, soaking the blend in hydrochloric acid solution for 3-5h, filtering, washing with distilled water to neutrality to obtain an acid treated blend;

② taking 0.5 part of silane coupling agent and 100 parts of 120 parts of ethanol solution with volume fraction of 75-95%, and obtaining silane hydrolysate after ultrasonic dispersion;

③ adding the acid treated blend into silane hydrolysate, stirring at 90-100 deg.C for 2-3h, vacuum filtering, washing with distilled water to neutrality, and drying to obtain modified blend;

④ adding modified blend 10-20% of the weight of the linear low density polyethylene, mixing at high speed, melting, extruding and granulating to obtain the modified linear low density polyethylene.

4. The acid-resistant ion exchange membrane of claim 1, wherein: the silane coupling agent is one of a silane coupling agent KH550, a silane coupling agent KH560 and a silane coupling agent KH 570.

5. The acid-resistant ion exchange membrane of claim 3, wherein the ultrasonic dispersion frequency of step ② is 80-100kHz and the dispersion time is 20-30 min.

6. The acid-resistant ion exchange membrane of claim 3, wherein the drying temperature of step ③ is 80-90 ℃ and the drying time is 8-10 h.

7. The acid-resistant ion exchange membrane as claimed in claim 3, wherein the linear low density polyethylene and the modified blend are blended at a high speed in step ④, and then placed in a twin-screw extruder, wherein the temperatures of the zones of the twin-screw extruder are 135-140 ℃ in the first zone, 145-145 ℃ in the second zone, 150-150 ℃ in the third zone, 150-155 ℃ in the fourth zone, 160-155 ℃ in the fifth zone, 165-170 ℃ in the sixth zone, 160-155 ℃ in the seventh zone, 160-155 ℃ in the die orifice and 160-100-120 r/min in the screw speed.

8. A method for preparing an acid-resistant ion exchange membrane sheet according to any one of claims 1 to 7, wherein: the method comprises the following steps:

s1, weighing the ion exchange resin powder and the modified linear low-density polyethylene according to the proportion, and mixing at a high speed to obtain a mixture;

s2, mixing the mixture for 8-10min at the temperature of 180-200 ℃, then adding polyethylene wax, and mixing uniformly to obtain a mixed material;

s3, heating the mixture in a two-roller machine to 210 ℃ and 230 ℃, adding the mixed mixture, extruding and shearing the mixture for 20-30min through a roller, adjusting the distance between the two rollers, and pulling out a first-stage membrane;

s4, adjusting the distance between rollers of the calender, adjusting the temperature of the rollers of the calender to 185-220 ℃, putting the primary membrane into the calender, and obtaining the acid-resistant ion exchange membrane after calendering, drawing, stripping, cooling, forming and cutting.

9. The method of claim 8, wherein the acid-resistant ion exchange membrane is prepared by the following steps: the high-speed mixing speed of S1 is 3000-4000r/min, and the mixing time is 5-10 min.

Technical Field

The invention relates to the technical field of diaphragm materials, in particular to an acid-resistant ion exchange diaphragm and a preparation method thereof.

Background

The ion exchange membrane is a high molecular membrane which contains ion groups and has selective permeability to ions in a solution, and is mainly used for desalting brackish water, desalting and concentrating the solution, softening and desalting boiler water and the like, wherein Electrodeionization (EDI) is one of innovative and innovative technologies in the field of water treatment in recent years, and is a water treatment technology combining electroosmosis and ion exchange, generally, the water purification process mainly comprises three times of filtration, namely ① primary filtration for removing substances such as insoluble silt and the like in water through a primary filtration membrane, ② secondary filtration for removing soluble divalent ions such as calcium ions and magnesium ions in water through a reverse osmosis membrane, ③ tertiary filtration for removing monovalent ions such as sodium ions and chloride ions in water through an ion exchange membrane, and ultrapure water can be obtained after the tertiary filtration.

Disclosure of Invention

Aiming at the defects in the prior art, the first object of the invention is to provide an acid-resistant ion exchange membrane which has the advantages of good acid corrosion resistance, good ion exchange performance and long service life.

The second purpose of the invention is to provide a preparation method of the acid-resistant ion exchange membrane, which has the advantages of simple processing technology and easy control.

In order to achieve the first object, the invention provides the following technical scheme: an acid-resistant ion exchange membrane comprises the following components in parts by weight:

6000 parts of ion exchange resin powder 5000-; the modified linear low-density polyethylene is prepared by modifying linear low-density polyethylene by nano silicon dioxide, sepiolite powder, microcrystalline cellulose and a silane coupling agent;

the linear low density polyethylene has a melt index of 2.0g/10min and a density of 0.9225g/cm³。

By adopting the technical scheme, the linear low-density polyethylene has good flexibility, strength, heat resistance and processability, the linear low-density polyethylene is used for replacing common polyethylene, the mechanical properties such as tensile strength, tensile strength and the like of the membrane can be improved, and the required strength can be achieved without hot-press molding of the membrane and mesh cloth; the modified linear low-density polyethylene has good compatibility with ion exchange resin powder, and can remove the coupling agent in the raw material; the polyethylene wax is used as a macromolecular dispersing agent, so that the dispersing uniformity of the ion exchange resin powder and the modified linear low-density polyethylene can be further improved; the raw materials of the ion exchange membrane do not need to be added with an antioxidant and a coupling agent containing metal ions, so that the membrane can not react with hydrochloric acid, when the ion exchange membrane is applied to an electrodeionization membrane stack, the membrane can not be corroded by the hydrochloric acid after scaling and is chemically cleaned, the water production resistivity of the membrane can still be above 16M omega cm, the performance and the service life of the membrane can not be influenced by the hydrochloric acid, and the service life of the membrane can be greatly prolonged.

The nano silicon dioxide is non-toxic, tasteless and pollution-free, has good ultraviolet resistance, can improve the ageing resistance, strength and acid corrosion resistance of a polyethylene material, the sepiolite is fibrous hydrous magnesium silicate, is non-toxic and nonradioactive, has good high temperature resistance, salt resistance and rheological property, can be dissolved in hydrochloric acid, is odorless and tasteless, mainly comprises β -1, 4-glucoside bond-combined straight-chain polysaccharide substance, has a lower polymer and a larger specific surface area, is insoluble in dilute acid, is modified by using the nano silicon dioxide, sepiolite powder, microcrystalline cellulose and a silane coupling agent, can enhance the linear low-density polyethylene to improve the mechanical strength of the linear low-density polyethylene, can still have good high-temperature oxidation resistance during membrane processing under the premise of removing an antioxidant, is beneficial to the fiber structure of the sepiolite powder and the reticular particle structure of the nano silicon dioxide after melt blending modification treatment, can also improve the mechanical strength of the linear low-density polyethylene and the ion exchange resin compatibility, can also improve the mechanical property of the linear low-density polyethylene, and can further improve the mechanical aging resistance and the mechanical aging resistance of the linear low-density polyethylene after melt blending modification.

Further, the ion exchange resin powder includes cation exchange resin powder and anion exchange resin powder; the cation exchange resin powder is styrene sulfonic acid type cation exchange resin, and the anion exchange resin powder is styrene quaternary ammonium type anion exchange resin.

By adopting the technical scheme, the styrene sulfonic acid type cation exchange resin and the styrene quaternary ammonium type anion exchange resin have better chemical and physical stability, and have the advantages of high strength, high exchange capacity and good selectivity.

The modified linear low-density polyethylene is further prepared by the following method, by weight, ① taking 15-20 parts of nano silicon dioxide, 3-7 parts of sepiolite powder and 1 part of microcrystalline cellulose, mixing the nano silicon dioxide, the sepiolite powder and the microcrystalline cellulose to obtain a blend, placing the blend in a hydrochloric acid solution, soaking for 3-5 hours, then carrying out suction filtration on the blend, washing the blend to be neutral by using distilled water to obtain an acid-treated blend;

② taking 0.5 part of silane coupling agent and 100 parts of 120 parts of ethanol solution with volume fraction of 75-95%, and obtaining silane hydrolysate after ultrasonic dispersion;

③ adding the acid treated blend into silane hydrolysate, stirring at 90-100 deg.C for 2-3h, vacuum filtering, washing with distilled water to neutrality, and drying to obtain modified blend;

④ adding modified blend 10-20% of the weight of the linear low density polyethylene, mixing at high speed, melting, extruding and granulating to obtain the modified linear low density polyethylene.

By adopting the technical scheme, the acid-soluble substances in the nano silicon dioxide, the sepiolite powder and the microcrystalline cellulose can be removed after the nano silicon dioxide, the sepiolite powder and the microcrystalline cellulose are subjected to acid treatment; after the silane coupling agent and an ethanol solution are subjected to ultrasonic dispersion to obtain silane hydrolysate, the acid treatment blend is subjected to modification treatment, so that the modification efficiency of the silane coupling agent on the acid treatment blend is improved; and then the modified blend and the linear low density polyethylene are subjected to melt blending modification, so that the modified blend is dispersed in a molecular chain network of the linear low density polyethylene, and the mechanical property of the linear low density polyethylene is improved.

Further, the silane coupling agent is one of a silane coupling agent KH550, a silane coupling agent KH560 and a silane coupling agent KH 570.

By adopting the technical scheme, the chemical name of the silane coupling agent is gamma-aminopropyltriethoxysilane, the chemical name of the silane coupling agent KH560 is gamma-glycidoxypropyltrimethoxysilane, and the chemical name of the silane coupling agent KH570 is gamma- (methacryloyloxy) propyltrimethoxysilane; the silane coupling agents KH550, KH560 and KH570 can be used for coupling the blend consisting of nano silicon dioxide, sepiolite powder and microcrystalline cellulose and the linear low-density polyethylene, and the dispersibility and compatibility of the blend and the linear low-density polyethylene can be improved, so that the obtained modified linear low-density polyethylene has good tensile strength and good compatibility with ion exchange resin; therefore, the coupling agent and the antioxidant containing metal ions can be removed in the formula of the product, so that the acid resistance of the membrane is improved.

Further, the ultrasonic dispersion frequency of step ② is 80-100kHz, and the dispersion time is 20-30 min.

By adopting the technical scheme, the dispersibility of the silane coupling agent in the ethanol solution is favorably improved under the condition that the ultrasonic dispersion frequency is 80-100 kHz.

Further, the drying temperature of the step ③ is 80-90 ℃, and the drying time is 8-10 h.

By adopting the technical scheme, the modified blend is dried at the temperature of 80-90 ℃, so that the moisture in the modified blend can be removed, and the stability of the performance of the membrane is improved.

Further, in the step ④, after the linear low density polyethylene and the modified blend are blended at a high speed, the blend is placed in a twin-screw extruder, and the temperatures of the zones of the twin-screw extruder are respectively 135-140 ℃, 140-145 ℃, 145-150 ℃, 150-155 ℃, 155-160 ℃, 165-170 ℃, 160-160 ℃, 155-160 ℃, 160-160 ℃ and 120-r/min.

In order to achieve the second object, the invention provides the following technical scheme:

a preparation method of an acid-resistant ion exchange membrane comprises the following steps:

s1, weighing the ion exchange resin powder and the modified linear low-density polyethylene according to the proportion, and mixing at a high speed to obtain a mixture;

s2, mixing the mixture for 8-10min at the temperature of 180-200 ℃, then adding polyethylene wax, and mixing uniformly to obtain a mixed material;

s3, heating the mixture in a two-roller machine to 210 ℃ and 230 ℃, adding the mixed mixture, extruding and shearing the mixture for 20-30min through a roller, adjusting the distance between the two rollers, and pulling out a first-stage membrane;

s4, adjusting the distance between rollers of the calender, adjusting the temperature of the rollers of the calender to 185-220 ℃, putting the primary membrane into the calender, and obtaining the acid-resistant ion exchange membrane after calendering, drawing, stripping, cooling, forming and cutting.

By adopting the technical scheme, after the ion exchange resin powder and the modified linear low-density polyethylene are mixed at a high speed, the mixing uniformity of the ion exchange resin powder and the modified linear low-density polyethylene can be improved, then the added polyethylene wax is divided into the high-molecular dispersing agent, the mixing uniformity of the raw materials can be improved, the massive mixed material with certain toughness is formed, the obtained mixed material can be further mixed after being extruded and sheared, and the prepared membrane has good acid corrosion resistance, ion exchange performance and long service life.

Further, the high-speed mixing speed of S1 is 3000-4000r/min, and the mixing time is 5-10 min.

By adopting the technical scheme, the raw materials are mixed at the speed of 3000-4000r/min, which is beneficial to improving the uniformity of the raw material mixing.

In summary, compared with the prior art, the invention has the following beneficial effects:

1. after the antioxidant and the coupling agent containing metal ions are removed from the raw materials of the ion exchange membrane, the ion exchange membrane still has good mechanical properties such as tensile yield strength and the like, and can reach the required strength without hot-press molding of the membrane and mesh cloth; after the linear low-density polyethylene is modified, the dispersion uniformity of the ion exchange resin in the polymer can be improved; the acid-resistant ion exchange membrane prepared by the invention is applied to the electrodeionization membrane stack, the membrane is not corroded by hydrochloric acid after being chemically cleaned after scaling, the water production resistivity of the electrodeionization membrane stack is not changed, and the membrane stack type performance and the service life are not influenced by hydrochloric acid;

2. the linear low-density polyethylene is modified by adopting the nano silicon dioxide, the sepiolite powder, the microcrystalline cellulose and the silane coupling agent, the raw materials are nontoxic and tasteless, secondary pollution to a water body is avoided, and the modified linear low-density polyethylene also has certain light aging resistance, so that the service life of the diaphragm is further prolonged.

Detailed Description

The present invention will be described in further detail below.

Preparation examples the nano-silica in the following preparation examples was selected from nanoscale spherical silica with a fineness of 2000 mesh, model R202, provided by corridor morning kun chemical building materials ltd; the sepiolite powder is sepiolite powder with the fineness of 400 meshes provided by Hebei Hemiangguan mineral products GmbH; the microcrystalline cellulose is selected from the group consisting of cellulose provided by Hibei Koron-Kelong-Biotech, Inc.; silane coupling agent KH550, silane coupling agent KH560 and silane coupling agent KH570 are prepared from south AmericaThe linear low density polyethylene is selected from LL DPE of model L D100AC provided by Yanshan petrochemical company, the melt index is 2.0g/10min, and the density is 0.9225g/cm³。

Preparation example 1 of modified Linear Low Density polyethylene ① A blend is obtained by mixing 15kg of nano-silica, 3kg of sepiolite powder and 1kg of microcrystalline cellulose, immersing the blend in 20 wt% hydrochloric acid solution for 3h, then carrying out suction filtration, washing with distilled water to neutrality, and obtaining an acid treated blend;

② dispersing 0.5kg of silane coupling agent KH550 and 100kg of 75% ethanol solution under the ultrasonic frequency of 80kHz for 20min to obtain silane hydrolysate;

③ adding the acid treated blend into silane hydrolysate, stirring for 2h at 90 deg.C, vacuum filtering, washing with distilled water to neutrality, and drying to obtain modified blend;

④ adding modified blend with 10% of the weight of the linear low density polyethylene, mixing at 3000r/min for 20min, putting the mixture into a double screw extruder, wherein the temperatures of the zones of the screw extruder are 135 ℃ in the first zone, 140 ℃ in the second zone, 145 ℃ in the third zone, 150 ℃ in the fourth zone, 155 ℃ in the fifth zone, 165 ℃ in the sixth zone, 155 ℃ in the seventh zone, 155 ℃ in the die orifice and 100r/min in the screw, melting, extruding and granulating to obtain the modified linear low density polyethylene.

Preparation example 2 of modified Linear Low Density polyethylene ① A blend was obtained by mixing 17.5kg of Nano silica, 5kg of sepiolite powder and 1kg of microcrystalline cellulose, immersing the blend in 20 wt% hydrochloric acid solution for 4 hours, then suction-filtering, washing with distilled water to neutrality, and then obtaining an acid-treated blend;

② dispersing 0.5kg of silane coupling agent KH560 and 110kg of ethanol solution with volume fraction of 85% under the ultrasonic frequency of 90kHz for 25min to obtain silane hydrolysate;

③ adding the acid treated blend into silane hydrolysate, stirring for 2.5h at 95 deg.C, vacuum filtering, washing with distilled water to neutrality, and drying to obtain modified blend;

④ adding a modified blend accounting for 15 percent of the weight of the linear low density polyethylene, mixing at a high speed of 3000r/min for 20min, placing the mixture into a double-screw extruder, wherein the temperatures of the zones of the screw extruder are respectively 138 ℃ in the first zone, 142 ℃ in the second zone, 148 ℃ in the third zone, 152 ℃ in the fourth zone, 158 ℃ in the fifth zone, 168 ℃ in the sixth zone, 158 ℃ in the seventh zone, 158 ℃ in the die orifice and 110r/min in the screw, and melting, extruding and granulating the mixture to obtain the modified linear low density polyethylene.

Preparation example 3 of modified Linear Low Density polyethylene ① preparation example 20kg of Nano silicon dioxide, 7kg of sepiolite powder and 1kg of microcrystalline cellulose were taken and mixed to obtain a blend, the blend was placed in a 20 wt% hydrochloric acid solution to be soaked for 5 hours, then the blend was filtered by suction and washed to neutrality with distilled water to obtain an acid treated blend;

② dispersing 0.5kg of silane coupling agent KH570 and 120kg of 95% ethanol solution under 100kHz ultrasonic frequency for 30min to obtain silane hydrolysate;

③ adding the acid treated blend into silane hydrolysate, stirring for 3h at 100 deg.C, vacuum filtering, washing with distilled water to neutrality, and drying at 90 deg.C for 10h to obtain modified blend;

④ adding a modified blend accounting for 20 percent of the weight of the linear low density polyethylene into the linear low density polyethylene, mixing the mixture at a high speed of 3000r/min for 20min, placing the mixture into a double-screw extruder, wherein the temperatures of all zones of the screw extruder are respectively 140 ℃ in the first zone, 145 ℃ in the second zone, 150 ℃ in the third zone, 155 ℃ in the fourth zone, 160 ℃ in the fifth zone, 170 ℃ in the sixth zone, 160 ℃ in the seventh zone, 160 ℃ in a die orifice and 120r/min in the screw, and melting, extruding and granulating the mixture to obtain the modified linear low density polyethylene.

Preparation example 4 of modified linear low density polyethylene this preparation example differs from preparation example 1 of modified linear low density polyethylene in that the raw material of step ① is obtained by replacing nano silica and sepiolite powder with an equal amount of microcrystalline cellulose.

Preparation of modified linear low density polyethylene 5 this preparation differs from preparation 1 of modified linear low density polyethylene in that the blend of step ① has not been acid treated.

Preparation example 6 of modified Linear Low Density polyethylene this preparation differs from preparation example 1 of modified Linear Low Density polyethylene in that the modified blend was added in an amount of 9% by weight of the linear low density polyethylene in step ④.

Preparation example 7 of modified Linear Low Density polyethylene this preparation example differs from preparation example 1 of modified Linear Low Density polyethylene in that the modified blend was added in an amount of 21% by weight of the linear low density polyethylene in step ④.