Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
  • B01D67/0081—After-treatment of organic or inorganic membranes
  • B01D67/0093—Chemical modification
  • B01D67/00931—Chemical modification by introduction of specific groups after membrane formation, e.g. by grafting
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/12—Chemical modification
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/12—Chemical modification
  • C08J7/16—Chemical modification with polymerisable compounds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2323/00—Details relating to membrane preparation
  • B01D2323/38—Graft polymerization
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S264/00—Plastic and nonmetallic article shaping or treating: processes
  • Y10S264/48—Processes of making filters
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S264/00—Plastic and nonmetallic article shaping or treating: processes
  • Y10S264/62—Processes of molding porous films

Definitions

• radical groups are introduced into the chain of the base polymer, for example by high-energy radiation, on which the grafting can be carried out by radical chain polymerization.
• the peptide bond can occur alone or in combination with other recurring structural units, e.g. in combination with the sulfone group:
• the polymers provided for the invention have a number of advantages which have led to their wide industrial use. Many representatives of polyamides are characterized by high mechanical strength and a high softening point, while the polyurethanes have very favorable elastic properties. In contrast, these polymers have certain disadvantages for practical use, which are in part due to the limited stability of the peptide or carbamic acid group. Degradation of these groups, for example as a result of hydrolytic, oxidative or radiation-chemical influences, leads to disadvantageous changes in the properties, as a result of which the field of use of the foils produced from these polymers is limited. Kind of monomers.
• Suitable amide-based monomers are: acrylamide, dimethylaminopropylmethacrylamide, methacrylamidopropyltrimethylammoniumc rid, 2-acrylamido-2-methyl-propanesulfonic acid, N- ylamidoglycolsulfonic acid, N-morphpolinopropyl methacrylamide, methacrylamidoglycolate methyl ether, N-hydroxyethyl methacrylamide, N- [tris (hydroxymethyl)] methyl methacrylamide.
• mono-ethylenically unsaturated monomers are: vinyl acetate, N-vinylpyrrolidone, 4-vinylpyridine, N-vinylimidazole.
• Graft polymerizations can be carried out both in the liquid phase, that is to say in the melt or solution, and in the solid phase, the base polymer generally having to be in a swollen form in order to allow the monomer to enter the chains of the base polymer enable.
• the swelling can take place either by the monomer itself or by a further component which is not involved in the polymerization itself.
• the grafting proceeds from the surface to the interior of the polymer. This can result in the resulting graft copolymer being soluble in the grafting medium, which accelerates the progress of the grafting because the diffusion paths do not lengthen during the grafting.
• the pores grow proportionally with an isotropic growth of the membrane matrix, the number of pores per unit area decreases, but their size increases, so that an overall increase in hydraulic permeability can be observed.
• the opposite occurs in the case of the pure surface grafting, ie if the grafting is restricted to the near-surface chain segments of the base polymer. Since the membrane matrix itself does not change its dimensions, but only an additional layer is grafted on, the outer dimensions also remain constant, and the grafted-on layer leads to a narrowing of the pores, so that the hydraulic permeability of the membrane decreases.
• inorganic and organic hypochlorites it is possible with a correspondingly long exposure time to quantitatively chlorinate, for example, nylon 6,6 membranes, ie to achieve the theoretical chlorine content of about 24% by weight of N-Cl-nylon.
• the surface grafting according to the invention already occurs much lower chlorine levels, in the order of 5-10% of this value.
• a certain disadvantage of the high chlorine contents required for surface grafting in the case of aqueous hyochlorite solutions is that on the one hand the damage to the membrane matrix due to oxidative side reactions, in particular at pH values above 6, the higher the higher the degree of chlorination is chosen, but only a tiny fraction of the imported chlorine is used for the grafting. If the residual chlorine remaining after the grafting is not completely removed by a separate reduction step, it will completely destroy the membrane when the material is stored.
• the pH of the chlorination liquor is of primary importance, although it can generally be said that the higher the pH, the greater the damage to the base polymer, in particular at values above 9.
• the rate of chlorination also decreases with increasing PH value.
• the preferred pH range is therefore between 5 and 7, with values around 6 being particularly preferred.
• a value of 6.3 seems to be particularly advantageous because the water solubility of the product decreases considerably.
• the preferred concentration range for chloramine T is between 0.1 and 3%, with values between 1 and 2% being particularly preferred.
• the chlorination can also be carried out with organic hypochlorites in organic solvents, such as, for example, t-butyl hypochlorite with methylene chloride, hexane and other inert organic solvents, the nature of the solvent having a considerable influence on the rate of chlorination and the achievable chlorine content.
• organic solvents such as, for example, t-butyl hypochlorite with methylene chloride, hexane and other inert organic solvents, the nature of the solvent having a considerable influence on the rate of chlorination and the achievable chlorine content.
• Solvents which have a swelling or dissolving power for the N-Cl derivative formed such as chlorinated hydrocarbons and aromatics, appear to lead to higher chlorine contents. Conversely, when using these solvents, the chlorination times must not be extended indefinitely, because otherwise the material can go into solution.
• the preferred reducing agent for the application of the method according to the invention is sodium dithionite and its secondary products, e.g. Rongalit.
• Other reducing agents such as hydrazine or ascorbic acid, the latter in the alkaline range, can also be used, but are less preferred.
• the redox potential according to the aspects of the invention is preferably kept constant by metering in the reducing agent concentrate, which is preferably a 2% solution of Na dithionite.
• the pH value is kept constant by lye dosing, unless it is preferred to buffer the liquor accordingly, which would make this unnecessary.
• Fig. 8 and 9 show the dependence of the area growth or the flow rate on the degree of grafting. Both the flow rate and the area growth are the same for the less chlorinated samples than the highly chlorinated samples with the same degree of grafting. The latter therefore preferably have surface grafting.
• emulsifier Arlatone G, ICI

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Health & Medical Sciences (AREA)
• Polymers & Plastics (AREA)
• General Chemical & Material Sciences (AREA)
• Medicinal Chemistry (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Inorganic Chemistry (AREA)
• Transplantation (AREA)
• Graft Or Block Polymers (AREA)
• Separation Using Semi-Permeable Membranes (AREA)

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Citations (3)

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• 1989
  • 1989-09-06 DE DE3929648A patent/DE3929648C1/de not_active Expired - Lifetime
• 1990
  • 1990-09-06 US US07/829,024 patent/US5215692A/en not_active Expired - Lifetime
  • 1990-09-06 DE DE9090913482T patent/DE59001328D1/de not_active Expired - Lifetime
  • 1990-09-06 EP EP90913482A patent/EP0490950B1/de not_active Expired - Lifetime
  • 1990-09-06 WO PCT/EP1990/001498 patent/WO1991003310A1/de not_active Ceased

Patent Citations (3)

Non-Patent Citations (3)

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