CN115702268A

CN115702268A - Sulfonated polystyrene nonwovens

Info

Publication number: CN115702268A
Application number: CN202180038094.XA
Authority: CN
Inventors: C·科斯塔斯; G·T·笛; M·奥斯特兰德; J·D·芬奇; M·奥尔森
Original assignee: DDP Specialty Electronic Materials US LLC
Current assignee: DDP Specialty Electronic Materials US LLC
Priority date: 2020-05-11
Filing date: 2021-05-03
Publication date: 2023-02-14
Also published as: KR20230041959A; JP2023526197A; WO2021231114A1; EP4150143A1

Abstract

Sulfonated polystyrene fibers having an average diameter from 450nm to 2000nm and a capacity from 0.05meq/g to 2.0 meq/g.

Description

Sulfonated polystyrene nonwovens

Background

The present invention generally relates to sulfonated polystyrene nonwovens and methods for making the same.

It is known to functionalize polystyrene fibers by sulfonation. For example, nitanan Todsapon, pharmaceutical Journal of Pharmaceutical Research [ Journal of Tropical drug Research ],2014, 13 (2), 191-197 disclose the sulfonation of polystyrene fibers used in controlled release drug delivery. However, this reference does not disclose sulfonated fibers that can be used to form nonwoven fabric mats for metal ion removal.

Disclosure of Invention

The invention relates to a sulfonated polystyrene nonwoven having an average diameter of from 450nm to 2000nm and a capacity of from 0.05meq/g to 2.0 meq/g.

Detailed Description

Unless otherwise indicated, all percentages are weight percentages (wt%) and all temperatures are in ° c. Unless otherwise indicated, the average is an arithmetic average. All manipulations were carried out at room temperature (from 18 ℃ to 25 ℃) unless otherwise stated. By first using 4.0M NaNO ₃ The aqueous solution exchanges the acidic sites and the capacity is then measured using a mettlerthodo (Mettler Toledo) T90 autotitrator by titrating the resulting acidified solution with 0.1M NaOH or calculated by mass balance of the sulfonation reaction.

Preferably, the polystyrene used to make the fibers is a high thermal crystalline polystyrene, preferably one that is acceptable in pharmaceutical processing.

Preferably, the average diameter of the fibers is at least 480nm, preferably at least 500nm, preferably at least 520nm; preferably no more than 1750nm, preferably no more than 1500nm, preferably no more than 1200nm, preferably no more than 1000nm, preferably no more than 800nm, preferably no more than 750nm, preferably no more than 700nm.

Preferably, the fibers are produced by a Hybrid Membrane Technique (HMT). This technique is described, for example, in US 7618579. Preferably, the fibers are made from a solution of polystyrene in an aprotic solvent. Preferred solvents are those capable of dissolving polystyrene at room temperature, and include, for example, N-Dimethylformamide (DMF), dimethylacetamide, methyl ethyl ketone, dichloromethane, and toluene. Preferably, the solution is processed by electroblowing under conditions that can be adjusted by known techniques to alter the fiber characteristics to produce a nonwoven fiber mat. Preferably, the concentration of polystyrene in the solvent is from 15 to 30wt%, preferably 18 to 27wt%. Preferably, the solution is processed on a single or multi-well electroblowing unit. Preferably, the fibers are spun onto a rotating drum.

Preferably, the fibers are treated with a crosslinking agent capable of crosslinking the polystyrene prior to sulfonation. Preferred crosslinking agents are aldehydes and dialdehydes, preferably formaldehyde/sulfuric acid or glutaraldehyde/sulfuric acid, preferably formaldehyde/sulfuric acid. Preferably, at least 90wt%, preferably at least 94wt%, preferably at least 96wt%, preferably at least 98wt% of the polystyrene molecules contain cross-links. The wt% of crosslinked polystyrene molecules can be determined by immersing the fiber in methylene chloride and weighing the soluble material, which is the polymer containing the crosslinked polystyrene molecules. Preferably, the temperature is from 20 ℃ to 110 ℃, preferably at least 45 ℃, preferably at least 55 ℃; the fibers are treated with the crosslinking agent at a temperature preferably not greater than 100 c, preferably not greater than 95 c. Both time and temperature may be adjusted to produce the desired degree of crosslinking, however typical times are preferably in the range of from 30 minutes to 6 hours, preferably 1 to 4 hours. Preferably, the treatment with the crosslinking agent is carried out in the absence of a catalyst under the conditions given above. If a catalyst (e.g. Ag) is used ₂ SO ₄ ) The time at a given temperature will be much shorter and can be adjusted to provide the desired characteristics.

Preferably, the fibers resulting from treatment with the crosslinking agent are sulfonated by contacting them with a sulfonating agent, which is preferably at least 80wt% (the remaining at least 95% being water), preferably at least 90wt%, preferably at least 94%. Sulfonating agents are agents capable of sulfonating aromatic rings. Preferred sulfonating agents include sulfuric acid, chlorosulfonic acid and oleum; sulfuric acid is preferred. Preferably, the sulfonation is carried out at a temperature of from 30 ℃ to 160 ℃, preferably at least 50 ℃, preferably at least 70 ℃: preferably not largeAt a temperature of 120 ℃, preferably not more than 110 ℃. Both time and temperature can be adjusted to produce the desired capacity, however typical times are preferably in the range from 30 minutes to 6 hours, preferably 1 to 4 hours. Preferably, the fibers are contacted with concentrated sulfuric acid for a time sufficient to produce sulfonated polystyrene fibers having a capacity of from 0.4meq/g to 2.0meq/g or any desired range contained therein. Preferably, the sulfonation is carried out in the absence of a catalyst under the conditions given above. If a catalyst (e.g. Ag) is used ₂ SO ₄ Acetic anhydride, trifluoroacetic anhydride) the time at a given temperature will be much shorter and the time can be adjusted to provide the desired characteristics.

Preferably, the capacity of the sulfonated nonwoven is at least 0.2meq/g, preferably at least 0.4meq/g, preferably at least 0.45meq/g, preferably at least 0.50meq/g, preferably at least 0.55meq/g, preferably at least 0.60meq/g, preferably at least 0.65meq/g; preferably not more than 1.8meq/g, preferably not more than 1.6meq/g, preferably not more than 1.5meq/g, preferably not more than 1.4meq/g, preferably not more than 1.3meq/g, preferably not more than 1.2meq/g, preferably not more than 1.1meq/g.

Examples of the invention

In these examples, the number followed by "C" (e.g., 30C) is understood to be the temperature in degrees celsius.

Preparing fibers:

polystyrene (PS) solutions were prepared using PS 685 grade D polystyrene obtained from Aldrich (Aldrich). The solvent is Dimethylformamide (DMF). Solutions having concentrations in the range of 21 to 25wt% were detected. The sample solution was spun on a single-hole electroblowing unit. The fibers were spun onto a rotating cylinder and the sample nonwoven was collected from the cylinder after run. A typical sample was prepared from a 21wt% solution with 0.1wt% salt added based on the solution. Typical basis weights range from 60 to 100 gsm. The typical distance between the spin pack assembly and the collector drum is 33cm. A typical applied voltage is 100kV. A typical spinning chamber temperature is 30C. Typical sample average flow rate (mean flow pours) is 1 micron.

Treatment with sulfuric acid and formalin

The nanofiber membrane (mean fiber diameter 1700 nm) was immersed in a bath containing a mixture of reagent grade concentrated sulfuric acid and formalin (37 wt% formaldehyde), typically 90: 10 sulfuric acid: formalin (V/V). The bath is typically heated to 70C for 3h and gently shaken on an orbital shaker at 60-120 rpm. Next, the bath was cooled to < 50C, the reaction fluid was decanted, and the membrane was slowly hydrated with 50% sulfuric acid and gradually diluted to pure DI water.

Sulphonation of

The nanofiber membrane treated with sulfuric acid/formalin was immersed in concentrated sulfuric acid (typically 96%), and then heated to 90C for 0 to 8h while shaking on a rail. Next, the bath was cooled to < 50C, the reaction fluid was decanted, and the membrane was slowly hydrated with 50% sulfuric acid, and then gradually diluted to pure DI water.

1. Conditions for sulfuric acid/formalin treatment in the top compartment, and conditions for sulfonation in the bottom compartment.

2. The results of the last two rows are obtained from the compressed fiber mat, which typically significantly degrades the properties measured herein. However, the acquisition of acceptable properties indicates that felts with a capacity of 0.49 or even lower are acceptable.

From the following PS membranes and AmberTec ^TM UP1400 ion exchange resin washes metal residues:

47mm disk nonwoven PS membrane (average fiber diameter: 1718nm, capacity: 0.67 meq/g), UP1400 resin (strongly acidic cation exchange) (d =4em, h =6 cm)

Reagent: low metal level HCl

Volume flow rate: the membrane was 6.9ml/min and the ion exchange resin was 5ml/min.

The metal content of the nonwoven PS film was reduced to 9.76ppb in 210 minutes, at which time the resin still had a metal content of 20.26 ppb.

After HCl washing, the medium is further rinsed with DI water to at least a pH > 5.

The metals were removed from the spiked solvent using PS membranes and ion exchange resins.

Propylene Glycol Methyl Ether Acetate (PGMEA) doped with 100ppb of each of Al, ca, cr, cu, fe, mg, mn, ni, K, na, sn, ti and Zn was passed through a column of 4cm x 6cm (D x h) packed with UP1400 resin and 47mm PS disks washed with HCl and DI water as described above. Volume flow rate: the membrane was 6.9ml/min and the ion exchange resin was 5ml/min. The residence time in the resin bed was 15min, while the residence time in the PS membrane disc was 3.5 seconds. The total metal content in the initial resin bed effluent was 512.7ppb and the total metal in the membrane disc effluent was 823.4ppb. The membrane disc removed 96% of the initial metal at a first residence time of 3.5 seconds, while the ion exchange membrane removed 94% of the initial metal at a first residence time of 15 min.

Claims

1. A sulfonated polystyrene nonwoven comprising fibers having an average diameter of from 450nm to 2000nm and a capacity of from 0.05meq/g to 2.0 meq/g.

2. The nonwoven of claim 1 having a capacity of from 0.4 to 1.5 meq/g.

3. The nonwoven of claim 2, wherein said fibers have an average diameter of from 450nm to 1750 nm.

4. The nonwoven of claim 3, wherein at least 90 weight percent of the polystyrene molecules contain cross-links.

5. A process for producing a sulfonated polystyrene nonwoven; the method comprises the following steps:

a) Providing polystyrene nonwoven fibers having an average diameter of from 450nm to 2000 nm;

b) Contacting the polystyrene fibers with a crosslinking agent at a temperature of from 30 ℃ to 150 ℃; and

c) Contacting the product of step b) with at least 90wt% sulfuric acid at a temperature of from 30 ℃ to 150 ℃.

6. A method according to claim 5, wherein the fibres have an average diameter of from 450 to 1750 nm.

7. The method of claim 6, wherein step c) is performed for a time sufficient to produce sulfonated polystyrene fibers having a capacity of from 0.4 to 2.0 meq/g.

8. The method of claim 7, wherein the crosslinking agent is sulfuric acid and an aldehyde or dialdehyde and wherein step b) is performed for a time sufficient to produce sulfonated polystyrene fibers, wherein at least 90wt% of the fibers contain crosslinks.

9. The method of claim 8, wherein step c) is performed for a time sufficient to produce sulfonated polystyrene fibers having a capacity of from 0.4meq/g to 1.5 meq/g.

10. A method for removing metal from a liquid, the method comprising contacting the liquid with a polystyrene nonwoven comprising fibers having an average diameter from 450nm to 2000nm and a capacity from 0.05meq/g to 2.0 meq/g.