A kind of film-forming method for improving liner microfiltration membranes surface flatnessTechnical field
The present invention relates to a kind of film-forming method for improving liner microfiltration membranes surface flatness, it is widely used in water processIn field.
Background technology
Belt material microfiltration membranes refer to lining-reinforced hollow-fibre membrane, are to increase bundle-shaped support in traditional hollowBody, to improve the intensity of film silk, its tensile strength and compression strength are significantly larger than common hollow-fibre membrane, and pulling force is more than50KG, its support body material is generally terylene material, and price is relatively inexpensive, the more braiding of current water treatment field supporterForm is compiled or crocheting method for high, and belt material microfiltration membranes are in simple terms equably to apply to spread separating layer in supporting body surface, bothWith reference to needing to keep certain adhesive force, antistripping effect will get well, and the film surface after smearing needs to reach certain smoothness,It is more smooth more uniform better in theory, to improve the contamination resistance of film in running.
Existing liquid phase separation masking method detailed process is resin, solvent, additive to be put into stir according to a certain percentageStirring and dissolving in kettle is mixed, enters coagulating bath split-phase, sizing through spinning kettle, filter, spinneret after casting solution deaeration, for belt materialFilm, supporter is combined through spinneret and in die orifice exit with casting solution, and casting solution is uniformly coated on supporting body surface shapeFilm forming silk, film silk by tentatively being shaped after coagulation bath, after by other gel grooves further by the DMAC (dimethyl in casting solutionAcetamide) separate out in aqueous, the principle of gel is the displacement of liquid liquid, and DMAC is diffused into water in feed liquid, and water diffuses to fenestraIn, wrapping wire, post-treating and other steps are eventually passed, ultimately form finished film silk.
As market competition is fierce all the more, some enterprises for doing film can reduce film production cost, and with lining form it is main intoOriginally it is supporter, when establishment density diminishes or mesh number is reduced, the gap of supporting body surface can increase, and casting solution was being smearedEasily occurs " bleed " (casting solution is flowed into or infiltered in supporter under incomplete gel state) problem in journey, after causing shapingFilm is rough, uneven, and needs to carry out formula some adjustment after there is this situation, but effect is not often obvious,And while change is formulated, film properties occur change, it is difficult to weigh.Want to reach same film surface flatness, needUsing mesh number supporter higher or the thicker separating layer of smearing, two methods can increase production cost, and supporter is worked outAfter density is less than to a certain degree, even if being also unable to reach the smooth effect in film surface by increasing smearing thickness.
The content of the invention
In order to overcome drawbacks described above present in existing film-forming method, the present invention to propose a kind of raising liner microfiltration membranes surfaceThe method of smoothness, the method is on the basis of not feed change, formula, to be optimized by spinning technique, in supporterAtomization process is carried out to supporter before smearing casting solution, the appropriate feed liquid gelation rate for accelerating casting solution and support contact level,Bleed is avoided the occurrence of, so as to reach the purpose of the smoothness for improving shaping caudacoria surface.Particular technique side of the inventionCase is as follows：
A kind of film-forming method for improving liner microfiltration membranes surface flatness, the method comprises the following steps：
(1) resin, solvent, additive are put into stirring and dissolving in stirred tank according to a certain percentage and form casting solution；
(2) spinneret is entered through spinning kettle, filter after making the casting solution deaeration to be formed；
(3) supporter is made to be combined with the casting solution so that casting solution is equably applied through spinneret and in die orifice exitOverlay on supporting body surface and form film silk；
(4) make film silk by tentatively being shaped after coagulation bath, after by other gel grooves further by the DMAC in casting solutionSeparate out in aqueous, and during water diffuses to fenestra, eventually pass wrapping wire, post processing and form finished film silk；
It is characterized in that：
The method be additionally included in supporter into atomization process is carried out to supporter before spinneret the step of.
Atomising device needed for above-mentioned atomization process is a sleeve, and sleeve is provided with multiple atomizers, can be by adjustingSeamless power and/or replacing different model atomizer change water-carrying capacity, reach different degrees of atomizing effect, general same ruleThe atomizer of lattice, pressure more high flow capacity is bigger, and the effect of atomization is stronger, can be turned on and off individually according to atomizing effect in additionAtomizer.According to the difference of fogging degree, casting solution can reach different degrees of gel effect after being contacted with supporter, typicallyFor, when from the supporter that cost is relatively low, mesh number is relatively low, need to be deeper to the atomization process degree of supporter, its principle isSolvent is exchanged with the mass transfer of non-solvent in homogeneous polymer solution surrounding environment, and phase point occurs from homogeneous polymer solutionFrom, it is transformed into a gel structure for three-dimensional macromolecular network type, final film-forming, and to the atomization process of supporter, canChange the combination speed of split-phase speed and film formation time, control casting solution and supporter, reach not only smooth but also bonded with certainThe purpose of power, fundamentally solves the problems, such as the film surface irregularity after film forming, reaches certain smoothness.
Feature of the present invention is due to being provided with the step of carrying out atomization process to supporter, so can be by reducing supporterMesh number or casting solution smearing thickness, reach the purpose of reduces cost, while the smoothness on film surface can be kept again, and atomization processIt is controllable, can arbitrarily be adjusted according to the characteristics of supporter and formula, atomization process cost is relatively low, need to only increase the mist machine and corresponding madeAtomizer, water consumption is less.
Brief description of the drawings
In order to be easier to understand technical scheme and beneficial technique effect, by referring to what is be shown in the drawingsSpecific embodiment of the invention is described in detail to the present invention.These accompanying drawings depict only typical case of the invention to be implementedMode, does not constitute the limitation to protection scope of the present invention, wherein：
Fig. 1 is the stream of the film-forming method of the raising liner microfiltration membranes surface flatness of an implementation method of the inventionCheng Tu.
Fig. 2 is used by the film-forming method of the raising liner microfiltration membranes surface flatness of above-mentioned implementation method of the inventionAtomising device perspective view.
It is micro- that Fig. 3-6 is respectively bleed degree when atomization quantity is 12cc/min, 20cc/min, 35cc/min and 47cc/minPhoto.
In the reference indicated in Fig. 1-2：
1：Stirred tank；2：Spinning kettle；3：Nitrogen pot；4：Supporter；5：Atomising device；6：Spinneret；7：Coagulating bath；8：ReceiveSilk machine；9：Sleeve；10：Atomizer.
Specific embodiment
Reference picture 1, a kind of masking of raising liner microfiltration membranes surface flatness of an implementation method of the inventionMethod is specially and resin, solvent, additive is put into stirring and dissolving formation casting solution in stirred tank 1 according to a certain percentage；Make shapeInto casting solution deaeration after through spinning kettle 2, filter enter spinneret 6.Optionally, spinning kettle 2 is connected with nitrogen pot 3, pastNitrogen is passed through in spinning kettle 2 for promoting casting solution spinning, nitrogen is advantageous in that stabilization, and casting solution is difficult to be oxidized.SupportBody 4 enters spinneret 6 and is combined with the casting solution so that casting solution is equal in the exit of spinneret 6 after being atomized through atomising device 5The surface of supporter 4 is coated in evenly forms film silk；Film silk tentatively shaped by after coagulation bath 7, after enter one by other gel groovesWalk and separate out in aqueous the DMAC in casting solution, and during water diffuses to fenestra, eventually pass wrapping wire, post processing and form finished productIn film silk income receive silk machine 8.
Atomising device 5 needed for above-mentioned atomization process is a sleeve 9, and sleeve is provided with atomizer 10.In the implementationIn mode, the internal diameter of sleeve 9 is 90mm, and external diameter is 100mm, and two groups of atomizers, every group of atomizer number are provided with sleeve 9It is four to measure, and four nozzles 10 in every group of atomizer are uniformly distributed along the circumferencial direction of sleeve, two groups of atomizers itBetween distance be 120mm, the distance of every group of atomizer sleeve ends nearest with it (can calculate the length of sleeve for 40mmIt is 200mm to spend).Water-carrying capacity can be changed by adjusting the atomizer 10 of pressure and replacing different model, reached in various degreeAtomizing effect, general same specification atomizer 10, pressure more high flow capacity is bigger, and the effect of atomization is stronger, in addition can rootIndivedual atomizers 10 are turned on and off according to atomizing effect.According to the difference of fogging degree, casting solution can after being contacted with supporter 4Different degrees of gel effect is reached, in general, when from the supporter 4 that cost is relatively low, mesh number is relatively low, need to be to supporter4 atomization process degree is deeper, its principle be homogeneous polymer solution surrounding environment in solvent exchanged with the mass transfer of non-solvent, fromIt is separated in homogeneous polymer solution, is transformed into a gel structure for three-dimensional macromolecular network type, is finally solidified intoFilm, and to the atomization process of supporter 4, split-phase speed and film formation time, the combination speed of control casting solution and supporter 4 can be changedDegree, reaches not only smooth but also with the purpose of certain cohesive force, fundamentally solves the problems, such as the film surface irregularity after film forming, reachesTo certain smoothness.
A diameter of 1.5-2.0mm of general supporter 4, and be according to the volume that above-mentioned size can calculate sleeve 91271.7cm3If the residence time in sleeve 9 of supporter 4 is 1 second, for the atomization process of supporter 4, its atomizer10 sizes should be at 100-150 μm, and atomization quantity is adjustable in 10-50cc/min, appropriate to add so as to realize different atomization process effectsThe feed liquid gelation rate of fast casting solution and the contact surface of supporter 4, it is to avoid the occurrence of bleed, so as to improve shaping caudacoria surfaceSmoothness.Fig. 3-6 is respectively bleed degree when atomization quantity is 12cc/min, 20cc/min, 35cc/min and 47cc/min and showsMicro- photo.It can be seen that film surface flatness effect is related to bleed degree from Fig. 3-6, bleed is more serious, and film surface is more notSmooth, as shown in figure 3, bleed is lighter, flat smooth is got on film surface, no concave-convex injustice phenomenon, as shown in Figure 6.
Certainly, those skilled in the art can according to actual needs to sleeve 9 size and the number of atomizer 10 andDistribution is adjusted, naturally it is also possible to the size of atomizer 10 and the numerical value of atomization quantity are adjusted according to atomizing effect, this is simultaneouslyWithout departing from protection scope of the present invention.
The present invention by the atomization process to supporter, can be reduced while film surface flatness is ensured supporter intoThis, preparation process is simple, controllable, and an adjustable variable is increased during casting solution is combined with supporter, increasesThe wide in range property of product.
The present invention can be embodied in other specific forms, but this is without departing from protection scope of the present invention, thisThe protection domain of invention is defined only by the following claims.