Method for manufacturing filter membrane for inhibiting microorganisms

Abstract

A method for manufacturing a filter membrane for inhibiting microorganisms includes the following steps: obtaining a nano-zinc precursor and dissolving it into water, adding at least one reducing agent and interfacial agent to the water, thereby reducing zinc ions of the nano-zinc precursor to zinc particles so as to form liquid having nano-zinc particles; respectively placing the liquid having nano-zinc particles and a polymer material into plastic masterbatch process equipment, respectively volatilizing the fluid having nano-zinc particles and polymer material through the plastic masterbatch process equipment, performing air extraction and mixing by the plastic masterbatch process equipment, and adding at least one grafting agent to perform a mixed graft link, allowing the nano-zinc particles and polymer material to be linked together stably so as to form a plastic masterbatch having nano-zinc particles; and making the plastic masterbatch into a filer membrane through film making equipment.

Claims

1. A method for manufacturing a filter membrane for inhibiting microorganisms, comprising the following steps: (a) obtaining a nano-zinc precursor, and dissolving said nano-zinc precursor into water; (b) adding at least one reducing agent and at least one interfacial agent in said water dissolved with said nano-zinc precursor, thereby reducing zinc ions of said nano-zinc precursor to nano-zinc particles so as to form a liquid having nano-zinc particles; (c) respectively placing said liquid having nano-zinc particles and a polymer material into plastic masterbatch process equipment by means of melt grafting, respectively processing said liquid having nano-zinc particles and said polymer material to be in a volatile state with said plastic masterbatch process equipment, mixing and linking said volatilized liquid having nano-zinc particles with said volatilized polymer material in the process of air extraction, and adding at least one grafting agent to perform a mixed graft link so as to form a plastic masterbatch having nano-zinc particles; and (d) making said plastic masterbatch having nano-zinc particles into a filter membrane having nano-zinc particles through film making equipment.

2. The method according to claim 1, wherein said nano-zinc precursor is zinc chloride, zinc gluconate, zinc acetate, zinc sulfate or zinc carbonate.

3. The method according to claim 1, wherein said reducing agent is one or more than one selected from a group constituted by hydrazine compounds, dextrose, sodium ascorbate and ascorbic acid, sodium carboxymethyl cellulose (CMC), SO.sub.2 and NaBH.sub.4.

4. The method according to claim 1, wherein said interfacial agent is one or more than one selected from a group constituted by cetyl trimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), polyvinylpyrrolidone (PVP), 3-(trimethoxysilyl)propyl methacrylate, MSMA, sodium hydrogen, methylsul foliate, dibenzoyl-L-tartaric acid (DBTA), 3-aminopropyltrimethoxy-silane (APTMS), and (3-mercaptopropyl)trimethoxysilane (MPTMS).

5. The method according to claim 1, wherein said polymer material is PET, PA6, PP, PE, ABS, PC, PVDF, PS, PES, PVC or PAN.

6. The method according to claim 1, wherein in said step (c) of respectively placing said liquid having nano-zinc particles, said melt grafting is to place said liquid having nano-zinc particles and a polymer material respectively in a plastic masterbatch process equipment having twin screw extrusion mechanism and at least six suction holes, said twin screw extrusion mechanism being in a vacuum state; said liquid having nano-zinc particles and polymer material are respectively placed in said plastic masterbatch process equipment, said liquid having nano-zinc particles and polymer material having a weight ratio ranged between 1:10 and 1:1; said liquid having nano-zinc particles and polymer material are respectively processed to be in a volatile state with said plastic masterbatch process equipment, allowing said volatilized liquid having nano-zinc particles and volatilized polymer material to be mixed and linked together through said twin screw extrusion and six suction holes in the process of air extraction; and at this point, at least one grafting agent is added therein to perform mixing, grafting and linking, thereby forming a plastic masterbatch having nano-zinc particles.

7. The method according to claim 1, wherein in said step (b) of adding at least one reducing agent, the manner of zinc ions of said nano-zinc precursor being reduced to said nano-zinc particles is to place zinc ions of Zn.sup.+2 concentration ranged from 110.sup.5 mole to 110.sup.3 mole in a glass bottle, deionized water (DI) is added in said glass bottle, and the concentration of sodium dodecyl sulfate the (SDS) is set to be ranged from 1 mM to 10000 mM, the concentration of cetyltrimethylammonium bromide (CTAB) from 1 mM to 10000 mM, the concentration of sodium carboxymethylcellulose (CMC) from 1 to 20 wt %; a solution in which a reducing agent Na.sub.2S.sub.2O.sub.5 is ranged from 1 to 5 gams and a strong reducing agent NaBH.sub.4 from 0.01 to 10M is added after stirred uniformly with a heating stirrer; in the process of stirring, said reducing agents are respectively added in; if said reducing agent has a high pH value, 0.1 to 40 l of concentrated hydrochloric acid is needed to drop in; at this point, the pH value of said solution is adjusted to about 1 to 5, and said solution is stirred continuously and placed into a hot water bath of temperature ranged from 50 to 90 degrees centigrade, and heated and stirred with a magnet electric heating stirrer, thereby reducing nano-zinc ions to nano-zinc particles.

8. The method according to claim 1, wherein in said step (b) of adding at least one reducing agent, the manner of zinc ions of said nano-zinc precursor being reduced to the nano-zinc particles uses a sonochemical method; said nano-zinc precursor is placed in a reaction bottle, and said reaction bottle is then placed in a ultrasonic oven, using ultrasonic oscillation to generate reduced free radicals to reduce metal ions so as to generate nano-zinc particles; metal salt aqueous solution is then placed in said reaction bottle, and said interfacial agent is added therein to stabilize said nano-zinc particles; said reaction bottle is placed in a ultrasonic oscillator and oscillated thereby, and a reaction is completed after 8 to 15 minutes is completed to reduce nano-zinc ions to nano-zinc particle.

9. The method according to claim 1, wherein in said step (b) of adding at least one reducing agent, said manner of zinc ions of said nano-zinc precursor being reduced to said nano-zinc particles uses an electrochemical method for generating metal nano-particles, the sizes of said nano-particles can be adjusted by controlling the current of electrolytic apparatus; thereby reducing said zinc ions of said nano-zinc precursor to said nano-zinc particles with said electrochemical method.

10. The method according to claim 1, wherein said grafting agent is maleic anhydride, acetic anhydride, glycidyl methacrylate, acrylamide or acrylic acid.

11. The method according to claim 1, therein said filter membrane having nano-zinc particles is a hollow fiber filter membrane, plate filer membrane.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a flow chart of a method for making a filter membrane for inhibiting microorganisms of the present invention;

(2) FIG. 2 shows a chemical formula of a nano-zinc being grafted on polyvinyl pyrrolidone (PVP);

(3) FIG. 3 shows a chemical formula of a nano-zinc being grafted on sodium dodecyl sulfate (SDS);

(4) FIG. 4 shows a process of a zinc ion of a nano-zinc precursor being reduced to a nano-zinc particle;

(5) FIG. 5 shows a chemical formula of nano-zinc particle grafted on PVDF through maleic anhydride (grafting agent);

(6) FIG. 6 shows a chemical formula of nano-zinc particle grafted on PES through maleic anhydride (grafting agent);

(7) FIG. 7 shows a chemical formula of nano-zinc particle grafted on PAN through maleic anhydride (grafting agent);

(8) FIG. 8 shows a chemical formula of nano-zinc particle grafted on PVC through maleic anhydride (grafting agent);

(9) FIG. 9 is a first test report of the method for manufacturing a filter membrane for inhibiting microorganisms of the present invention;

(10) FIG. 10 is a second test report of the method for manufacturing a filter membrane for inhibiting microorganisms of the present invention;

(11) FIG. 11 is a third test report of the method for manufacturing a filter membrane for inhibiting microorganisms of the present invention; and

(12) FIG. 12 is a fourth test report of the method for manufacturing a filter membrane for inhibiting microorganisms of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(13) Referring to FIG. 1, a method for manufacturing a filter membrane for inhibiting microorganisms of the present invention includes the following steps:

(14) step 100: obtaining a nano-zinc precursor capable of being dissolved in water, and dissolving the nano-zinc precursor into water, where the nano-zinc precursor may be zinc chloride, zinc gluconate, zinc acetate, zinc sulfate or zinc carbonate capable of being dissolved in water; for example, zinc dioxide being dissolved in water: Zn.sup.2+(s)+2e.sup..fwdarw.Zn (aq)

(15) step 110: adding at least one reducing agent and at least one interfacial agent into the water in which the nano-zinc precursor is dissolved, thereby reducing the zinc ions of the nano-zinc precursor to nano-zinc particles so as to form a liquid having nano-zinc particles; namely, reducing nano-zinc ions to nano-particles with the reducing agent, and then using the interfacial agent to be in combination with the nano-zinc particles by means of chemical grafting, allowing the reduced nano-zinc particles not to be in combination with other particles (i.e. preventing secondary agglomeration from being generated among the nano-zinc particles), thereby forming the reduced stable nano-zinc particles, where the reducing agent may be one or more than one selected from a group constituted by hydrazine compounds, dextrose, sodium ascorbate and ascorbic acid, sodium carboxymethyl celluiose (CMC), SO.sub.2, NaBH.sub.4, and the like.

(16) The interfacial agent may be one or more than one selected from a group constituted by cetyl trimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), polyvinylpyrrolidone (PVP), 3-(trimethoxysilyl)propyl methacrylate, sodium hydrogen methylsulfonate (MSMA), Dibenzoyl-L-tartaric acid (DBTA), 3-aminopropyltrimethoxy-silane (APTMS), (3-Mercaptopropyl)trimethoxysilane (MPTMS).

(17) step 120: respectively placing the liquid having nano-zinc particles and a polymer material into plastic masterbatch process equipment by means of melt grafting, respectively processing the liquid having nano-zinc particles and polymer material to be in a volatile state through the plastic masterbatch process equipment, performing air extraction and mixing with the plastic masterbatch process equipment, allowing the volatilized liquid having nano-zinc particles and volatilized polymer material to be added with at least one grafting agent so as to carry out a mixed graft link in the process of air extraction, thereby forming a plastic masterbatch having nano-zinc particles, where the polymer material may be plastics such as PET, PA6(NYLON), PP, PE, ABS, PC, PVDF, PS, PES, PVC, PAN, and the like.

(18) step 130: making the plastic masterbatch having nano-zinc particles into a filter membrane having nano-zinc particles through film making equipment.

(19) In the step 110, the interfacial agent grafting the nano-zinc particles by means of chemical grafting in the process of nano-zinc particle being linked with the interfacial agent is a modification process, which allows the nano-zinc particles not to be liked with other particles. Furthermore, the nano-zinc particles are then formed into a composite material after the nano-zinc particles interact with the interfacial agent through chemical grafting process. For example, after PVP interacts with the nano-zinc particle after chemical grafting process, the chemical formula thereof is shown in FIG. 2, and after SDS interacts with the nano-zinc particles through chemical grafting process, the chemical formula thereof is shown in FIG. 3.

(20) In the step 110, when CMC is selected for the interfacial agent, with CMC being dissolvable in water solution to cause it to be sticky and thick, allowing the nano-zinc particles to move more slowly in the sticky and thick water solution so that the chance of the collision and agglomeration thereof is reduced, thereby stabilizing them. In addition, the size distribution of the nano-zinc particles can be changed by changing temperature and/or adjusting the concentration of the reducing agent, achieving the purpose of handling particle size.

(21) In a first preferred embodiment of the present invention, the zinc ions of the nano-zinc precursor being reduced to the nano-zinc particles in the step 110 is specifically described. The zinc ions of Zn.sup.+2 concentration ranged from 110.sup.5 mole to 110.sup.3 mole are placed in a glass bottle, deionized water (DI) is added in the bottle, and the concentration of sodium dodecyl sulfatethe (SDS) is set to be ranged from 1 mM to 10000 mM, the concentration of cetyltrimethylammonium bromide (CTAB) from 1 mM to 10000 mM, the concentration of sodium carboxymethylcellulose (CMC) from 1 to 20 wt %. Thereafter, a solution in which a reducing agent Na.sub.2S.sub.2O.sub.5 is ranged from 1 to 5 grams and a strong reducing agent NaBH.sub.4 from 0.01 to 10M is added after stirred uniformly with a heating stirrer. In the process of stirring, the reducing agents are respectively added in. At this point, it should be noted that if the reducing agent has a high pH value, 0.1 to 40 l of concentrated hydrochloric acid is needed to drop in; at this point, the pH value of the solution is adjusted to about 1 to 5, and the solution is stirred continuously and placed into a hot water bath of temperature ranged from 50 to 90 degrees centigrade, and heated and stirred with a magnet electric heating stirrer, thereby reducing nano-zinc ions to nano-zinc particles, the process of which is shown in FIG. 4.

(22) In a second preferred embodiment of the present invention, the zinc ions of the nano-zinc precursor being reduced to the nano-zinc particles is further specifically described. A sonochemical method (i.e. the use of ultrasound to promote the reduction) is used; the nano-zinc precursor is placed in a reaction bottle, and the reaction bottle is then placed in a ultrasonic oven, using ultrasonic oscillation to generate reduced free radicals to reduce metal ions so as to generate nano-zinc particles. Furthermore, metal salt aqueous solution is then placed in the reaction bottle, and the interfacial agent is added therein to stabilize the nano-zinc particles. Thereafter, the reaction bottle is placed in a ultrasonic oscillator and oscillated thereby, and the reaction is completed after 8 to 15 minutes to obtain the nano-zinc particles; the reaction mechanism thereof is H.sub.2O.fwdarw.H+OH (sonolysis)-OH(H)+RH.fwdarw.R (reducing species)+H.sub.2O (H.sub.2)RH.fwdarw.R (reducing species)+-H (sonolysis)-R(reducing species)+Zn(M1)++H++R+. The driving force of this reaction mechanism comes from air pockets generated from shock waves, or .OH or .H formed between air pockets and the solution, and the reduction of carbon chain molecules generates .R free radicals; or RH between interfaces is oscillated to form .R free radicals, which have redox reaction with metal ions to reduce the metal ions to metal nanoparticles of zero-valence.

(23) In a third preferred embodiment of the present invention, the zinc ions of the nano-zinc precursor being reduced to the nano-zinc particles is further specifically described. An electrochemical method is used; this electrochemical method is published by Reetz, M. T. and Helbig, W. in year 1994, being used to generate metal nano-particles, the sizes of which can be adjusted by controlling the current of electrolytic apparatus. Therefore, the present invention can use the electrochemical method to reduce the zinc ions of the nano-zinc precursor to nano-zinc particles; the process thereof is shown as the following:

(24) $\begin{array}{cc}\mathrm{Anode}\text{:}& {\mathrm{Met}}_{\mathrm{bulk}}.fwdarw.{\mathrm{Met}}^{n+}+n{e}^{-}\\ \mathrm{Cathode}\text{:}& {\mathrm{Met}}^{n+}+n{e}^{-}+\mathrm{stabilizer}.fwdarw.\\ & {\mathrm{Met}}_{\mathrm{coll}}\text{/}\mathrm{stabilizer}\\ \mathrm{Sum}\text{:}& {\mathrm{Met}}_{\mathrm{bulk}}+\mathrm{stabilizer}.fwdarw.\\ & {\mathrm{Met}}_{\mathrm{coll}}\text{/}\mathrm{stabilizer}\end{array}$

(25) In the step 120, the melt grafting is to place the liquid having nano-zinc particles and a polymer material respectively in a plastic masterbatch process equipment, which has twin screw extraction mechanism and at least six suction holes, where the twin screw extraction mechanism is in a vacuum state. The liquid having nano-zinc particles and the polymer material are respectively placed in the plastic masterbatch process equipment, where the liquid having nano-zinc particles and polymer material have a weight ratio ranged between 1:10 and 1:1. Whereby, the liquid having nano-zinc particles and polymer material are respectively processed to be in a volatile state with the plastic masterbatch process equipment, allowing the volatilized liquid having nano-zinc particles and volatilized polymer material to be mixed and linked together through the twin screw extraction and six suction holes in the process of air extraction. At this point, at least one grafting agent is added therein to perform the mixed graft link, thereby forming a plastic masterbatch having nano-zinc particles, where the addition amount of the grafting agent is between 0.1% and 5% by weight based on the weight percent of the polymer material weight.

(26) The grafting agent may be maleic anhydride (MAA), which has a molecular formula C.sub.4H.sub.2O.sub.3 and chemical formula

(27) ##STR00001##

(28) The grafting agent may also be glycidyl methacrylate (GMA), which has a molecular formula C.sub.7H.sub.10O.sub.3 and chemical formula

(29) ##STR00002##

(30) The grafting agent may also be acrylamide (AM), which has a molecular formula CH.sub.2CHCONH.sub.2 and chemical formula

(31) ##STR00003##

(32) The grafting agent may also be acrylic acid (AAM), which has a molecular formula C.sub.3H.sub.4O.sub.2 and chemical formula

(33) ##STR00004##

(34) In a preferred embodiment, the chemical formulae for the nano-zinc particles of the present invention grafted on PVDF, PES, PAN, and PVC are explained, where FIG. 5 shows a formula for the nano-zinc particle of the present invention being grafted on PVDF through maleic anhydride (MAA); FIG. 6 shows a formula for the nano-zinc particle of the present invention added being grafted on PES through maleic anhydride (MAA); FIG. 7 shows a formula for the nano-zinc particle of the present invention being grafted on PAN through maleic anhydride (MAA); and FIG. 8 shows a formula for the nano-zinc particle of the present invention being grafted on PVC through maleic anhydride (MAA).

(35) Therefore, the present invention is featured in that a nano-zinc precursor is first reduced to obtain nano-zinc particles, nano-zinc ions being reduced to nano-zinc particles with a reducing agent, an interfacial agent is used to be linked with the nano-zinc particles by means of chemical grafting, allowing the reduced nano-zinc particles not to be in combination with other particles any more, preventing secondary agglomeration from being generated among nano-zinc particles, thereby obtaining the stable reduced nano-zinc particles; thereafter, at least one grafting agent is then added to perform a mixed graft link to form a plastic masterbatch having nano-zinc particles by means of melt grafting, which is to use plastic masterbatch process equipment to respectively process the liquid having nano-zinc particles and a polymer material to be in a volatile state, and mix them in the process of air extraction, allowing the nano-zinc particles to be linked with the polymer material uniformly and stably to form a plastic masterbatch having nano-zinc particles; finally, the plastic masterbatch having nano-zinc particles is made into a filter membrane having nano-zinc particles through film making equipment. Here, the filter membrane having nano-zinc particles so made is a hollow fiber filter membrane, a plate filer membrane or other type of filter membrane.

(36) It should be noted that using the melt grafting manner allows the nano-zinc particles to be linked with polymers without affecting the mechanical properties of polymers, and even allows plastics to have very good physical performance, for example, the improvement of ductility and toughness. Therefore, the present invention can prevent the defects generated from traditional manufacturing in which any type of organic or inorganic antibacterial agent is added in casting solution; the present invention has grafted nano-zinc particles on the polymer material before film-forming, allowing the polymer material to be formed into a homogeneous casting solution after dissolved in a film-forming solution such as DMF, DMAC or NMP, preventing effectively the serious issue of the uneven dispersion or agglomeration of the antibacterial agent. Furthermore, the casting solution is allowed to reduce effectively the dissolution amount of zinc particles in the process of water bath for phase change, ensuring the zinc equivalent of the filter membrane products, and obtaining a concentration that inhibits microorganisms. For example, the filter membrane of the nano-zinc particles prepared by the present invention can reach the standard of more than 600 ppm per unit particle.

(37) Referring to FIG. 9, which shows a first test report, the test date is Feb. 9, 2015, and it can be known from the test result that a plastic masterbatch made from the zinc containing plastic solvent of the present invention has zinc content per unit up to 12,700 ppm.

(38) Referring to FIG. 10, which shows a second test report, the test date is Apr. 27, 2015, and it can be known from the test result that a hollow silk film made of the plastic masterbatch having nano-zinc particles of the present invention has the zinc content up to 851 ppm.

(39) Referring to FIG. 11, which shows a third test report, the test date is Sep. 30, 2015, and it can be known from the test result that a PS hollow silk film made of the plastic masterbatch having nano-zinc particles of the present invention has zinc content up to 845 ppm.

(40) Therefore, it can be known from the above three test reports that the method for making a filter membrane still can have similar or close results even under the same construction method, the same formula, different time and different equipment condition, which proves that the plastic masterbatch having nano-zinc particles of the present invention is repeatable; it is undoubted that the present invention has this advantage.

(41) Referring to FIG. 12, which shows a fourth test report, the test date is Sep. 30, 2016; it can be known from the test result that the amount of zinc elements washed from the plastic masterbatch having nano-zinc particles is only 3 ppm in the process of casting solution phase transition water bath; the instrument can not detect if the washed zinc element is less than 2 ppm according to this test method. So, it can be concluded form the test data that zinc elements are not easy to be washed out from the plastic masterbatch having nano-zinc particles of the present invention, and most of them are remained in fiber film silk; the detected washed-out zinc amount 3 ppm can be proved to be quite low.

(42) The filter membrane having nano-zinc particles so made can be used for the filtration of liquid or gas; zinc particle being antibacterial allows the filter membrane having nano-zinc particles to be capable of decomposition of bacteria and inhibition of bacterial growth. In addition, nano-zinc particles being stably linked with polymer material allows nano-zinc particles not to be easy to be lost gradually from the filter membrane having nano-zinc particles after water wash, capable of maintaining the antibacterial capacity of the filter membrane effectively.

(43) It is worth noting that the filter membrane having nano-zinc particles of the present invention being capable of inhibiting bacterial growth is using a constant 3.3 eV power gap carried by nano-zinc oxide to force the extracellular molecules of microbial bacteria or ammonia molecules to break when the nano-zinc oxide is in contact with microbial bacteria or ammonia molecules to cause, for example, mechanisms such as the metabolism, nutrition in the outer membrane of bacteria to be lost, and thus to promote cell death, thereby achieving the decomposition of bacterial and inhibition of bacterial growth.

(44) Furthermore, the power gap will cause water molecules H.sub.2O in the air to be free when the filter membrane having nano-zinc particles of the present invention is applied to the filtration of ammonia gas molecules; this kind of reaction needs H.sub.2O to participate to form (OH) radicals, which will react with NH.sub.3 to take H away from it to form NH.sub.2 gradually, and finally, N is further in combination with other N to form a stable N.sub.2 molecule, the decomposition formula of the entire NH.sub.3 is shown as the following:
NH.sub.(m-1)+OH.fwdarw.NH.sub.m.sup.+H2O,
and finally, the free nitrogen atom will be in combination with a nitrogen atom: N+N.fwdarw.N2 to form nitrogen gas.