Backing material and semi-transparent film composite materialTechnical field
The present invention relates to technology field of membrane materials, in particular to a kind of backing material and semi-transparent film composite material.
Background technique
In sea water desalination, the purification of drinking water profound level, sanitary sewage disposal, drug concentration, haemodialysis, food concentration etc.Field, semi-permeable membrane is as a kind of efficient filtering material, with its higher efficiency and lower use cost, gradually by more nextMore concern, application and popularizations.Semi-permeable membrane is generally by cellulosic resin, polyester resin, polysulfones resinoid, polyamide-basedThe synthetic resin such as resin, fluororesin are constituted, and bulk strength is lower when these materials are used as semi-permeable membrane, it is difficult in semi-permeable membraneLong-term stable operation under nominal working conditions can not be used alone.As solution, semi-permeable membrane needs fid when in useMaterial provides intensity, i.e., uses it with the non-woven fabric compounded mode together as backing material.
United States Patent (USP) US6919026B2 discloses a kind of preparation method of reverse osmosis membrane backing material, patent of invention benefitWith chemical fibre and conventional papermaking process, the mode including cylinder, fourdrinier wire, inclined wire, to prepare backing material.Although the patent proposesA kind of method of reverse osmosis membrane backing material, but the unresolved problems of backing material in actual use, for example, it is hotThe problem of warpage is easy after processing.Specifically, semipermeable membrane support material material side coats the semi-permeable membrane film layer being formed by polyme, warpCross following process so that being formed by composite material has a degree of separating capacity, eventually become microfiltration membranes, ultrafiltration membrane,One of nanofiltration membrane and reverse osmosis membrane etc..Under normal circumstances, it needs first to dissolve the polymer in when prepared by semi-permeable membrane film layer moltenIt is configured to certain density solution in agent, is then coated in backing material surface, is solidified by coagulating bath and then remove solvent.It is moltenAgent volatilization generates stress and concentrates, and polymer is precipitated from solvent in coagulating bath and forms semi-permeable membrane film layer on backing material surfaceWhen, also stress can be generated in that side of its coated side concentrate.This stress concentration can eventually lead to film and generate warpage, meeting when seriousIt crimps, it is clear that this warpage is all unfavorable for production process and use.
Chinese patent CN 103429327B discloses a kind of supporter of film, which uses upper layer and lower layer construction stretchThe semipermeable membrane support material material that the mode of hot pressing more common than different lamellas is prepared, can avoid generating after coating polysulfones solutionBetween warpage the phenomenon that.Although the patent by upper layer and lower layer structure asymmetry handle in the way of attempt to solve coating polysulfones solutionThe phenomenon that generating warpage afterwards, but this is by allowing backing material to generate the warpage of coated side opposite direction come negative interaction coating in advanceFace warping phenomenon, i.e. backing material inherently have warpage when uncoated, when next step is processed since warpage equally can bandCarry out problems.In addition, also and not yet in effect solving the problems, such as that wherein one layer of draw ratio is excessive, influences the intensity of final products.
Summary of the invention
The main purpose of the present invention is to provide a kind of backing materials and semi-transparent film composite material, to solve in the prior artSemipermeable membrane support material material is easy the problem of warpage after heat treatment.
To achieve the goals above, according to an aspect of the invention, there is provided a kind of backing material, backing material includeMain fibre, the coated side and non-coated face that there is backing material through-thickness to be oppositely arranged, through-thickness, from coated sideThe section major diameter of the main fibre of backing material to the 1/5~1/3 of backing material thickness is R1, from non-coated face to supportThe section major diameter of the main fibre of backing material at the 1/5~1/3 of material thickness is R2, R1< R2。
Further, above-mentioned R1Between 6~14 μm.
Further, above-mentioned R2Between 7~20 μm.
Further, above-mentioned backing material further includes the adhesive fiber being distributed between main fibre；It is preferred that main body is fineThe melting temperature of dimension is higher than the melting temperature of adhesive fiber.
Further, aforementioned body fiber and adhesive fiber are each independently selected from polyester fiber, polyolefine fiber, gatherOne of nylon, aramid fiber, polyimide fiber or a variety of conjugate fibers.
Further, non-woven fabrics is used to prepare above-mentioned backing material for raw material, the non-woven fabrics for forming backing material is wet processNon-woven fabrics, electrospinning non-woven fabrics or the three-dimensional set non-woven fabrics that non-woven fabrics that papermaking obtains, the dry method of paper-making obtain.
Further, above-mentioned non-woven fabrics is single-layer nonwoven or mostly forms at non-woven fabrics is stacked.
Further, above-mentioned backing material is formed by carrying out hot pressing to non-woven fabrics.
According to another aspect of the present invention, it provides a kind of semi-transparent film composite material, including backing material and is supported on branchThe semi-permeable membrane of the coated side of timbering material, the backing material which is any of the above-described kind.
Further, above-mentioned semi-permeable membrane is cellulosic resin film, polyester resin film, polysulfones resin film, polyamideResin film or fluororesin film.
It applies the technical scheme of the present invention, makes the close coated side of backing material and the main fibre close to non-coated faceSection major diameter generates difference, i.e. the section major diameter close to the main fibre of coating surface side is fine less than the main body close to non-coated surface sideThe section major diameter of dimension, i.e. R1< R2, coated side and non-coated face is made to have the bonding between different superficial density and fiber strongDegree, i.e., non-coated face porosity is lower, superficial density is bigger, while having stronger adhesive strength, has it than coated sideHigher intensity has so as to offset the stress generated during forming semi-permeable membrane after coated side coated polymer solutionAlleviate the generation for even being eliminated warping phenomenon in effect ground.Further, the coated side of the application backing material has higher holeGap rate makes polymer solution generate preferable infiltration within a short period of time, generates between backing material after removal of the solvent enoughBig interaction, to guarantee to form active force powerful enough between semi-permeable membrane and backing material, it is ensured that under applying working conditionStable operation.
Detailed description of the invention
The accompanying drawings constituting a part of this application is used to provide further understanding of the present invention, and of the invention showsExamples and descriptions thereof are used to explain the present invention for meaning property, does not constitute improper limitations of the present invention.In the accompanying drawings:
Fig. 1 shows the section SEM photograph of embodiment 1 according to the present invention；
Fig. 2 shows the coated side SEM photographs of embodiment 1 according to the present invention；
Fig. 3 shows the non-coated face SEM photograph of embodiment 1 according to the present invention.
Wherein, the above drawings include the following reference numerals:
11, main fibre；12, adhesive fiber；111, the section major diameter of main fibre.
Specific embodiment
It should be noted that in the absence of conflict, the features in the embodiments and the embodiments of the present application can phaseMutually combination.The present invention will be described in detail below with reference to the accompanying drawings and embodiments.
Term explanation:
Since in hot pressing, the interface of regular circle cross-section fibers will become oval, class ellipse or irregularShape, but along the direction with pressure perpendicular, can Formation cross-section major diameter, the direction parallel with pressure can Formation cross-sectionMinor axis, if it is irregular shape then section full-size become section major diameter.
As the application background technique is analyzed, it is easy warpage after the semipermeable membrane support material material heat treatment of the prior art, isSolve the problems, such as this, this application provides a kind of backing material and semi-transparent film composite material.
In a kind of typical embodiment of the application, a kind of backing material is provided, which includes main body fibreDimension, the coated side and non-coated face that there is backing material through-thickness to be oppositely arranged, wherein through-thickness, from coated sideThe section major diameter of the main fibre of backing material to the 1/5~1/3 of backing material thickness is R1, from non-coated face to supportThe section major diameter of the main fibre of backing material at the 1/5~1/3 of material thickness is R2, R1< R2。
It is poor that the section major diameter of the close coated side of the backing material of the application and the main fibre close to non-coated face generatesDifferent, i.e., the section major diameter close to the main fibre of coating surface side is less than the section major diameter of the main fibre close to non-coated surface side,That is R1< R2, make coated side and non-coated face that there is the adhesive strength between different superficial density and fiber, i.e., non-coated faceGap rate is lower, superficial density is bigger, while having stronger adhesive strength, it is made to have higher intensity than coated side, thusThe stress generated during forming semi-permeable membrane after coated side coated polymer solution can be offset, effectively alleviates and even is eliminatedThe generation of warping phenomenon.Further, the coated side of the application backing material has higher porosity, makes polymer solutionPreferable infiltration is generated within a short period of time, generates sufficiently large interaction between backing material after removal of the solvent, thusGuarantee to form active force powerful enough between semi-permeable membrane and backing material, it is ensured that the stable operation under applying working condition.
In order to further increase the active force between semi-permeable membrane and backing material, preferably above-mentioned R1Between 6~14 μm.It willR1Control can make the main fibre of coated side sufficiently fine and be distributed more uniform, it is easier to generate and divide between 6~14 μmCloth is uniform and sizeable surface hole defect, more preferably permeates so that polymer solution be made to generate within a short period of time, withGuarantee the raising to the active force between semi-permeable membrane and backing material.
Master for the backing material at the non-coated face to the 1/5~1/3 of the backing material thickness of the applicationThe section major diameter of body fiber is meeting R1< R2On the basis of, it is selected within the scope of common section major diameter from the prior art,It is preferred that R2Between 7~20 μm, to provide higher support strength.
In backing material, in order to improve the support strength of backing material, preferably above-mentioned backing material further includes being distributed inAdhesive fiber between main fibre.Main fibre is bonded using adhesive fiber, improves the knot between fiberWith joint efforts, and then integrated support intensity is improved.
In the hot pressing for being subsequently formed semi-permeable membrane, in order to improve the effect performance of adhesive fiber and guarantee main fibreIntensity, the preferably melting temperature of aforementioned body fiber are higher than the melting temperature of adhesive fiber.Further preferred aforementioned body is finePeacekeeping adhesive fiber is each independently selected from polyester fiber, polyolefine fiber, Fypro, aramid fiber, polyimidesOne of fiber or a variety of conjugate fibers.
According to the customary preparation methods of current backing material, it is preferred to use non-woven fabrics is that raw material prepares backing material, shapeNon-woven fabrics at backing material is non-woven fabrics, the electrospinning non-woven fabrics or vertical that non-woven fabrics, the dry method of paper-making that wet papermaking obtains obtainBody set non-woven fabrics.The above-mentioned obtained non-woven fabrics of various forms can be used as the raw material of the backing material of the application.
Since the Main change of the backing material of the application concentrates on coated side and non-coated face, either single layer withoutWoven fabric or multi-layer nonwoven fabrics can be employed as preparing the raw material of above-mentioned backing material, i.e., non-woven fabrics be single-layer nonwoven or mostly atNon-woven fabrics is stacked to be formed.
Preferably, above-mentioned backing material is formed by carrying out hot pressing to non-woven fabrics.In hot pressing, by adjusting hot pressingTemperature or pressure and other parameters the fiber on two surfaces of non-woven fabrics can be made to form differentiation, for example there is above-mentioned section major diameterDifferentiation.Above-mentioned hot-pressing processing is processed using roll-type commonly used in the art or caterpillar hot-press equipment.
In hot pressing, since the melting temperature (or heat distortion temperature) of main fibre is higher than the melting of adhesive fiberTemperature, then adhesive fiber melts at processing temperatures or when deformation occurs, main fibre still is able to maintain fiber substantiallyOverall structure, in the case where heating pressurized treatments, deformation occurs for main fibre, but when deformation occurs, also not up to main fibreMelting temperature, the main still generation (i.e. on section) on perpendicular to length direction of the deformation of main fibre.
Due to adhesive fiber melting, flowing after non-woven fabrics hot pressing processing, the shape of original fiber has been lost, andThe amorphous shape for being similar to round or polygon is formed, although the sectional dimension of finally formed backing material can not be effectiveMeasurement, but according to the difference of coated side and non-coated face process conditions, the change in size for being formed by adhesive fiber is also abided byFollow the law of dimension of main fibre.Electronic Speculum shows that the dispersibility of the adhesive fiber of coated side is better than non-coated faceThe dispersibility of adhesive fiber.
Following embodiment is schematically given at the respective cross-section major diameter data formed under special process, and being not offered as can only beIt can just be obtained under specific technique.Above-mentioned hot pressing is at corresponding R1Between 6~14 μm, R2Between 7~20 μm and divideThe concrete technology condition of the depth of cloth, you can get it by general adjustment by those skilled in the art, such as the hot pressing processing usedWhen technique, the section major diameter of final surface fiber can all be influenced according to the change of speed, pressure, raw material material, temperature etc., and beMake for same material, it is fine in order to obtain same coated side surface body fiber width and non-coated face surface bodyWidth is tieed up, kinds of processes parameter can also be used.It is believed that the combination of this technological parameter, is more.Therefore withUnder embodiment in, in order to more intuitively reflect the beneficial effect of the invention patent, only directly list the fibre after final moldingThe parameter of dimension.
In another typical embodiment of the application, a kind of semi-transparent film composite material, including backing material are providedWith the semi-permeable membrane for the coated side for being supported on backing material, the backing material which is any of the above-described kind.
Since the warpage issues of the backing material of the application are improved, the support strength of semi-permeable membrane is also obtainedImprove；Simultaneously because the coated side of the application backing material has higher porosity, make polymer solution in the short periodThe interior preferable infiltration of generation, generates sufficiently large interaction, to guarantee semi-permeable membrane between backing material after removal of the solventActive force powerful enough is formed between backing material, it is ensured that the stable operation under applying working condition.
The backing material of the application due to be physical structure variation, application range is wider, when semi-permeable membrane be fibreWhen tieing up plain resin film, polyester resin film, polysulfones resin film, polyamide-based resin film or fluororesin film, this can be usedThe backing material of application is supported.
The beneficial effect of the application is further illustrated below with reference to embodiment and comparative example.
In following embodiment, the Specifications reference standard of semipermeable membrane support material material is as follows:
" grammes per square metre " of semipermeable membrane support material material is measured according to GB/T 451.2-2002 method.
" thickness " of semipermeable membrane support material material is measured according to GB/T 451.3-2002 method.
" fluffing " of semipermeable membrane support material material is measured according to the method mentioned in Chinese patent CN103429327A.Specific as follows: by the non-woven fabrics doubling of width 30cm, with the diameter 5cm of stainless steel, the cylindrical roller of length 40cm is in folding linePlace rolls three times back and forth, the fluffing radical of the fiber generated by visual observation or at microscopical method calculating folding line.At least surveyThree different locations are tried, its average value is calculated.
0~10: fluffing is few, is very good level.
11~20: for good level.
21~30: for the threshold level used.
31 or more: for not available level.
" air permeability " of semipermeable membrane support material material is measured according to JIS L1096, using frazier type testing machine, unitFor cc/cm2s。
When the coated side of semipermeable membrane support material material coats semi-permeable membrane, observe whether it can crimp to coating surface side.HalfThe crimpiness of permeable membrane backing material, if crimping, is labeled as labeled as "●" if not finding to crimp by visually observing“○”。
When measuring the fibre section major diameter of semipermeable membrane support material material, it can be observed by directlying adopt scanning electron microscopeThe width (i.e. perpendicular to the data in fibre length direction) of main fibre in coated side and non-coated face, can also be by by semi-permeable membraneObserve its section after backing material low-temperature brittle fracture, fibre section is general oval or irregular, edge close to ellipseThe size in pressure perpendicular direction is fibre section major diameter, and being parallel to pressure direction is fibre section minor axis.Following embodimentSection major diameter with comparative example is to directly adopt scanning electron microscope to observe main fibre on its coated side and non-coated faceWidth.
Embodiment 1
Composition: main fibre is the polyester fiber of high melt temperature, and adhesive fiber is the polyester fiber of low melting glass,Wherein, main fibre mass fraction is 60%, and melting temperature is that 260 DEG C of adhesive fiber mass fractions are 40%, melting temperatureIt is 180 DEG C.
After preparing non-woven fabrics using dry method of paper-making method, hot pressing working process is carried out, wherein hot pressing temperature is 200 DEG C, line pressurePower is 150kg/cm, and be supported material.
The section major diameter of the main fibre of coated side is 6 μm, and the section major diameter of the main fibre in non-coated face is 10 μm.
The structure of above-mentioned backing material can be referring to figs. 1 to Fig. 3, wherein Fig. 1 shows the partial cross section of the backing materialSEM photograph, wherein it can be observed that main fibre 11 and adhesive fiber 12, main fibre 11 is in apparent fine in Fig. 1 to 3Shape is tieed up, can obviously observe the section major diameter 111 of main fibre, and the shape of adhesive fiber 12 is then irregular, comparison diagram 2With Fig. 3 it is evident that the section major diameter of the main fibre of coated side is less than the section major diameter of the main fibre in non-coated face.
Embodiment 2
Composition: main fibre is the polyester fiber of high melt temperature, and adhesive fiber is the polyester fiber of low melting glass,Wherein main fibre mass fraction is 60%, and melting temperature is 265 DEG C, and adhesive fiber mass fraction is 40%, melting temperatureIt is 150 DEG C).
After preparing non-woven fabrics using wet papermaking method, hot pressing working process is carried out, wherein hot pressing temperature is 200 DEG C, line pressurePower is 150kg/cm, and be supported material.
The section major diameter of the main fibre of coated side is 6 μm, and the section major diameter of the main fibre in non-coated face is 7 μm.
Embodiment 3
Composition: main fibre is the polyester fiber of high melt temperature, and adhesive fiber is polyolefine fiber, wherein main bodyFiber quality score is 60%, and melting temperature is 255 DEG C, and adhesive fiber mass fraction is 40%, and melting temperature is 135 DEG C).
After preparing non-woven fabrics using dry method of paper-making method, hot pressing working process is carried out, wherein hot pressing temperature is 200 DEG C, line pressurePower is 150kg/cm, and be supported material.
The section major diameter of the main fibre of coated side is 14 μm, and the section major diameter of the main fibre in non-coated face is 20 μm.
Embodiment 4
Composition: main fibre is the aramid fiber of high melt temperature, and adhesive fiber is polyester fiber, wherein main body is fineTieing up mass fraction is 60%, and without specific melting temperature, adhesive fiber mass fraction is 40%, and melting temperature is 175 DEG C).
After preparing non-woven fabrics using wet papermaking method, hot pressing working process is carried out, wherein hot pressing temperature is 200 DEG C, line pressurePower is 150kg/cm, and be supported material.
The section major diameter of the main fibre of coated side is 8 μm, and the section major diameter of the main fibre in non-coated face is 13 μm.
Embodiment 5
Composition: main fibre is the polyester fiber of high melt temperature, and adhesive fiber is the polyester fiber of low melting glass,Wherein, main fibre mass fraction is 60%, and melting temperature is 255 DEG C, and adhesive fiber mass fraction is 40%, melting temperatureIt is 135 DEG C).
After preparing non-woven fabrics using dry method of paper-making method, hot pressing working process is carried out, wherein hot pressing temperature is 200 DEG C, line pressurePower is 150kg/cm, and be supported material.
The section major diameter of the main fibre of coated side is 5 μm, and the section major diameter of the main fibre in non-coated face is 10 μm.
Embodiment 6
Composition: main fibre is the polyester fiber of high melt temperature, and adhesive fiber is the polyester fiber of low melting glass,Wherein, main fibre mass fraction is 60%, and melting temperature is 255 DEG C, and adhesive fiber mass fraction is 40%, melting temperatureIt is 135 DEG C).
After preparing non-woven fabrics using dry method of paper-making method, hot pressing working process is carried out, wherein hot pressing temperature is 200 DEG C, line pressurePower is 150kg/cm, and be supported material.
The section major diameter of the main fibre of coated side is 7 μm, and the section major diameter of the main fibre in non-coated face is 30 μm.
Embodiment 7
Composition: main fibre is the polyester fiber of high melt temperature, and adhesive fiber is polyolefine fiber, wherein main bodyFiber quality score is 60%, and melting temperature is 255 DEG C, and adhesive fiber mass fraction is 40%, and melting temperature is 135 DEG C).
After preparing non-woven fabrics using dry method of paper-making method, hot pressing working process is carried out, wherein hot pressing temperature is 200 DEG C, line pressurePower is 150kg/cm, and be supported material.
The section major diameter of the main fibre of coated side is 16 μm, and the section major diameter of the main fibre in non-coated face is 20 μm.
Comparative example 1
Composition: main fibre is the polyester fiber of high melt temperature, and adhesive fiber is the polyester fiber of low melting glass,Wherein, main fibre mass fraction is 60%, and melting temperature is 255 DEG C, and adhesive fiber mass fraction is 40%, melting temperatureIt is 135 DEG C).
After preparing non-woven fabrics using dry method of paper-making method, hot pressing working process is carried out, wherein hot pressing temperature is 200 DEG C, line pressurePower is 150kg/cm, and be supported material.
The section major diameter of the main fibre of coated side is 6 μm, and the section major diameter of the main fibre in non-coated face is 6 μm.
Comparative example 2
Composition: main fibre is the polyester fiber of high melt temperature, and adhesive fiber is the polyester fiber of low melting glass,Wherein, main fibre mass fraction is 60%, and melting temperature is 255 DEG C, and adhesive fiber mass fraction is 40%, melting temperatureIt is 135 DEG C).
After preparing non-woven fabrics using dry method of paper-making method, hot pressing working process is carried out, wherein hot pressing temperature is 200 DEG C, line pressurePower is 150kg/cm, and be supported material.
The section major diameter of the main fibre of coated side is 12 μm, and the section major diameter of the main fibre in non-coated face is 8 μm.
Backing material described in embodiment and comparative example is successively carried out to coating polysulfones solution, wherein polysulfones in polysulfones solutionMass fraction be 15%, according to 15mL/m2Polysulfones solution coated weight coated.After coating obtains polymer film, 110DEG C drying.Observe the crimpiness of complex.
Dependence test and evaluation acquired results are carried out such as to semipermeable membrane support material material in Examples 1 to 7 and comparative example 1~2Shown in table 1.
Table 1
Note: zero * indicates very slight crimp.
In Examples 1 to 7, it is all satisfied after the main fibre hot pressing on semipermeable membrane support material material coated side and non-coated face surfaceThe present invention claims ranges.It is found by test performance, the backing material of embodiment 1 to 7 will not generate curling after preparation, togetherWhen, it will not crimp after coated polymer film, in addition to this, other performances meet requirement.
Comparative examples 1 and embodiment 1 to 7, it is found that when the main fibre on coated side and non-coated face surface passes throughWhen section major diameter after hot pressing processing is consistent, the surface strength of two sides is consistent, after coating polysulfones solution, because of coating surface sideThe tension of generation is larger, integrally can there is a phenomenon where crimp.
Comparative examples 2 and embodiment 1 to 7, it is found that when the section major diameter of the main fibre on coated side surface is greater thanWhen the section major diameter of the main fibre on non-coated face surface, after coating polysulfones solution, the tension that coating surface side generates is larger, wholeThere is a phenomenon where crimp.
Comparative example 5 and embodiment 1 to 4, it is found that although after hot pressing is processed, the main body on coated side surfaceThe section major diameter of fiber is less than the section major diameter of the main fibre on non-coated face surface, but non-coated face surface body fiber is cutFace major diameter is smaller, can not generate enough surface strengths and be completely counterbalanced by the surface tension generated after coated side coating polysulfones, stillThe phenomenon that slight curling has occurred.Simultaneously because coated side main fibre is smaller by pressure, bonding effect good enough is not generated,Cause fluffing relatively poor.
Comparative example 6 and embodiment 1 to 4, it is found that although after hot pressing is processed, the main body on coated side surfaceThe section major diameter of fiber is less than the section major diameter of the main fibre on non-coated face surface, after backing material surface coats polysulfones,Surface strength is sufficiently large, will not integrally crimp, but since the section major diameter of the main fibre in non-coated face is excessive, causesThe air permeability on final non-coated face surface is smaller.
Comparative example 7 and embodiment 1 to 4, it is found that although after hot pressing is processed, the main body on coated side surfaceThe section major diameter of fiber is less than the section major diameter of the main fibre on non-coated face surface, after backing material surface coats polysulfones,Surface strength is sufficiently large, will not integrally crimp, but since the section major diameter of the main fibre of coated side is excessive, causes mostThe air permeability on non-coated face surface is smaller eventually.
It can be seen from the above description that the above embodiments of the present invention realized the following chievements:
It is poor that the section major diameter of the close coated side of the backing material of the application and the main fibre close to non-coated face generatesDifferent, i.e., the section major diameter close to the main fibre of coating surface side is less than the section major diameter of the main fibre close to non-coated surface side,That is R1< R2, make coated side and non-coated face that there is the adhesive strength between different superficial density and fiber, i.e., non-coated faceGap rate is lower, superficial density is bigger, while having stronger adhesive strength, it is made to have higher intensity than coated side, thusThe stress generated during forming semi-permeable membrane after coated side coated polymer solution can be offset, effectively alleviates and even is eliminatedThe generation of warping phenomenon.Further, the coated side of the application backing material has higher porosity, makes polymer solutionPreferable infiltration is generated within a short period of time, generates sufficiently large interaction between backing material after removal of the solvent, thusGuarantee to form active force powerful enough between semi-permeable membrane and backing material, it is ensured that the stable operation under applying working condition.
The foregoing is only a preferred embodiment of the present invention, is not intended to restrict the invention, for the skill of this fieldFor art personnel, the invention may be variously modified and varied.All within the spirits and principles of the present invention, made any to repairChange, equivalent replacement, improvement etc., should all be included in the protection scope of the present invention.