CN116459673A - Vertical flow filter element and preparation method thereof - Google Patents

Abstract

The application relates to the technical field of filtering devices, in particular to a vertical flow filtering element and a preparation method thereof. The scheme can improve the bonding performance between the liquid inlet guide screen and the filter layer, so that the membrane package can better maintain the integrity and the filter performance of the membrane in the processes of preparation, processing, use and storage.

Description

Vertical flow filter element and preparation method thereof

Technical Field

The application relates to the technical field of filtering devices, in particular to a vertical flow filtering element and a preparation method thereof.

Background

In the biomedical field, it is necessary to separate the product by means of a filter device in order to intercept compounds of a specific molecular weight. The membrane separation method relates to a radial flow filtration method and a vertical flow filtration method, wherein the vertical flow filtration method refers to a filtration method with the liquid flow direction and the filtration direction being perpendicular, and the liquid flows through a filtration medium while passing through a flow passage due to the shearing force generated on the surface of the filtration medium by the liquid flow, and meanwhile, the flowing liquid can further drive macromolecular substances blocked by the filtration medium to continuously flow forwards, so that filtrate for filtering out the macromolecular substances and concentrated solution containing the macromolecular substances are obtained by separation.

A membrane pack is a filter element commonly used for vertical flow filtration, and its conventional structure includes a filtrate unit and a liquid feed unit stacked in order, and a housing for fixing the above structures. Wherein the filtrate unit comprises a filter layer-runner-filter layer structure, and the liquid inlet unit is a screen with runners. When the liquid to be filtered flows in the screen, the shearing force can promote the liquid to pass through the filter layer, so that macromolecular substances are retained in the screen, and the separation and concentration effects are realized.

The filter layer plays the most critical role in the separation process, and among various filter layer materials, cellulose materials have wide application in many scenes due to good hydrophilicity. In the prior art, a membrane package of a cellulose membrane is often coated by silica gel, and the cellulose membrane and a screen are bonded together by the silica gel. But in the actual use process, the viscosity of the silica gel to the cellulose membrane is poor, and processing flaws easily occur in the process of processing the filter assembly, so that the quality and the yield of the filter assembly are affected.

Disclosure of Invention

In order to improve the yield of membrane package processing, the membrane package can better keep the integrity and the filtering performance of the membrane in the processes of preparation, processing, use and storage.

The vertical flow filter element has at least one liquid inlet end and at least one liquid outlet end, and specifically comprises the following components:

the liquid inlet diversion screen is provided with at least one first liquid inlet hole and at least one first filtrate hole;

the filtrate diversion screen is provided with at least one second liquid inlet hole and at least one second filtrate hole;

the filter layer is provided with a liquid inlet surface and a liquid outlet surface;

the liquid inlet guide screen meshes and the filtrate guide screen meshes are alternately stacked, and a filter layer is arranged between each two adjacent liquid inlet guide screen meshes and filtrate guide screen meshes; the liquid inlet surface of the filter layer faces the liquid inlet guide screen adjacent to the liquid inlet guide screen, the liquid outlet surface of the filter layer faces the filtrate guide screen adjacent to the liquid inlet guide screen, a liquid inlet flow channel is formed between the liquid inlet surfaces of two adjacent filter layers, and a filtrate flow channel is formed between the liquid outlet surfaces of two adjacent filter layers;

a first bonding layer is arranged between the filter layer and the liquid inlet guide screen and used for sealing and isolating a first filtrate hole and a filtrate flow passage, and the liquid inlet surface of the filter layer has an SEM average pore diameter not lower than 200nm, specifically, can have average pore diameters of 200nm, 300nm, 400nm, 500nm, 600nm, 800nm, 10000nm, 1200nm, 1500nm and 2000 nm; the first bonding layer is a thermosetting adhesive, and has a thermosetting temperature not higher than 150 ℃; the first adhesive layer has an adhesion of not less than 10000cps at room temperature, and the first adhesive layer has at least one temperature point when heated to 45-150deg.C so that the first adhesive layer has an adhesion of not more than 1000cps.

The thermosetting glue is a high molecular resin system which can generate internal physical or chemical reaction under the condition of heating so as to generate irreversible curing phenomenon, and can be optionally epoxy resin, polyurethane, phenolic resin, urea-formaldehyde resin, phenolic resin, furan resin or other resins with heating curing property, the thermosetting temperature is the lowest temperature at which the thermosetting glue can generate curing reaction, and most thermosetting resins can generate crosslinking reaction under the action of curing agents to form a curing system so as to lose fluidity.

The first bonding layer of the thermosetting adhesive material has fluidity which rises along with the rise of temperature, and can be firstly adhered to the surface of the liquid inlet guide screen in the sizing process, and the first bonding layer can permeate into the screen at low temperature due to larger pores of the screen. In this application, it is limited that the viscosity of first tie coat is not less than 10000cps under room temperature, and under this viscosity range, first tie coat can spread comparatively evenly in the feed liquor water conservancy diversion screen cloth, can realize better sealed effect and bonding effect. If a first adhesive layer with too low a viscosity is used, the first adhesive layer cannot be set on the liquid inlet guide screen, resulting in a filter element with poor integrity. After the liquid inlet diversion screen mesh and the filter layer are compounded, the first bonding layer is heated, and after the viscosity of the first bonding layer is reduced, the first bonding layer can be infiltrated into the filter layer through pores on the surface of the filter layer.

In this application, because the filter layer itself has two sides different pore size, under the general condition, because the flow direction of liquid is from feed liquor water conservancy diversion screen cloth flow direction filtrate water conservancy diversion screen cloth, consequently usually filter layer feed liquor level one side has bigger hole in liquid face one side, so set up can improve filterable effect, reduce the piling up of filter residue, increase the loading capacity of membrane package. In view of the above, the adhesive layer needs to be disposed between the liquid inlet guide screen and the filter layer, so that the thermosetting adhesive permeates into the filter layer, at least permeates to the surface of the filter layer, and further fixation and sealing are achieved.

In the above process, the heating temperature is not higher than 150 ℃, and the too high temperature can lead to the decrease of the permeability of the filter membrane, thereby affecting the filtering effect. Under the general condition, the first bonding layer lower than 1000cps can smoothly permeate into the pores of the liquid inlet surface of the filter layer under the action of extra negative pressure, and the filter layer and the liquid inlet guide screen can be bonded together after solidification, so that on one hand, the mechanical strength of the filter layer is improved through the supporting effect of the liquid inlet guide screen, the filter layer is not easy to damage in the preparation process, and on the other hand, the phenomena of cheapness and breakage of materials in the process flow are also reduced.

Preferably, the first adhesive layer has at least one temperature point in the range of 60 to 120 ℃ so that the viscosity of the first adhesive layer is 100 to 1000cps.

In the process that the thermosetting adhesive is heated and permeates into the pores of the filter layer, the thermosetting adhesive can permeate from the liquid inlet surface to the liquid outlet surface of the filter layer in the direction perpendicular to the plane of the filter layer, and can diffuse to the periphery along the plane of the filter layer, and in the actual production process, the trend of the thermosetting adhesive permeating and permeating into the filter layer can be enhanced by applying negative pressure on the liquid outlet surface of the filter layer. The viscosity in the range of 100-1000 cps is selected in the technical scheme, the limiting temperature is 60-120 ℃, the influence of the construction temperature range on the property of the filter layer is small, and the thermosetting adhesive in the viscosity range has proper fluidity, so that the thermosetting adhesive cannot cover excessive areas on the filter layer due to the excessively strong fluidity.

The properties of the best thermosetting glue that is suitable for use are also different for filter layers with different properties. Therefore, on the basis of the scheme, at least one temperature exists in the range of 60-120 ℃ in the one adhesive layer, and the viscosity and the area ratio of the inlet liquid level holes of the filter layer meet the following relation: y=k ₁ And/ln (2-x), wherein y is the viscosity of the first adhesive layer at the thermosetting temperature, x is the hole area ratio of the side of the filter layer facing the liquid inlet guide screen, and k ₁ Is constant and ranges from 75 to 300cps.

In a more preferred case, k ₁ The preferred range is 100-250 cps, and the film package has better integrity when the thermosetting adhesive used for the first adhesive layer is epoxy resin.

Preferably, the filter layer has a hole area ratio in the range of 30-60% on the side facing the liquid inlet guide screen.

After the thermosetting adhesive is heated, the fluidity is enhanced and the viscosity is weakened with the rise of the temperature before the thermosetting adhesive is cured, and in the filter layer, the larger the surface hole area ratio of the filter layer is, the easier the thermosetting adhesive is permeated into the filter layer, and the hole area ratio of the filter layer and the minimum viscosity of the thermosetting adhesive are in positive correlation.

After a plurality of experiments, the applicant finds that the parameters of the experimental result can be better fitted by adopting the formula, and the larger the area ratio of the holes is, the larger the viscosity range of the first bonding layer which can be accommodated by the filter layer is, and the thermosetting adhesive which is most suitable for a system can be calculated by utilizing the area ratio of the holes of the filter layer through the formula.

Preferably, the relevant parameters of the liquid inlet guide screen mesh and the viscosity of the thermosetting adhesive at room temperature have the following relation: y is ₂ ＝k ₂ d/l, wherein d is the diameter of a monofilament of the liquid inlet guide screen, l is the average distance between two adjacent filaments in the same direction in the liquid inlet guide screen, and k ₂ Is the parameter, its rangeThe circumference is 25000-150000 cps.

The thermosetting adhesive is required to be attached to the surface of the liquid inlet guide screen, and then is attached to the filter layer in a hot melting mode and the like. Therefore, in addition to having a certain relationship with the properties of the filter layer, the thermoset glue needs to adhere to the inlet guide screen at room temperature, and thus has a certain relationship with the properties of the inlet guide screen. The ratio between the monofilament diameter of the liquid inlet guide screen and the average distance between two adjacent filaments actually measures the density degree of fibers on the surface of the liquid inlet guide screen, when a sparser liquid inlet guide screen is selected, thermosetting adhesive with higher viscosity at normal temperature can be adopted, the thermosetting adhesive with high viscosity is not easy to rapidly diffuse along the plane of the liquid inlet guide screen, the filtering area of the liquid inlet guide screen and the filtering layer is potentially improved, and meanwhile, the spreading state of the adhesive liquid in the liquid inlet guide screen is also favorable for improving the sealing property and the integrity of a membrane package.

Preferably, the monofilament diameter of the liquid inlet guide screen is in the range of 50-500 μm.

Preferably, the average distance between two adjacent wires in the same direction in the liquid inlet guide screen is in the range of 50-500 μm.

Preferably, the inlet flow guide screen has a pore size of 200-800 μm.

Preferably, the liquid inlet guide screen has a porosity of 25-50%.

Experiments show that the liquid inlet guide screen mesh in the range is more suitable for bonding with thermosetting glue, and has better limiting effect on the adhesive capacity and the diffusion capacity of the thermosetting glue.

Preferably, a first isolation layer is arranged between the filter layer and the liquid inlet guide screen, and the thermosetting adhesive passes through the first isolation layer.

The first isolation layer can play roles in supporting the flow channel, improving the strength of the filter layer, improving the bonding strength and the like. The isolation layer can be made of non-woven fabrics and other materials. After the flow channel is regulated by the supporting layer, viruses, antibodies or other macromolecular proteins can pass through, so that the loss of materials is reduced. In addition, utilize the isolation layer and pass through the tie coat of isolation layer and fix the filter layer, can make the filter layer keep comparatively smooth state, reduce the deformation of filter layer, and then reduce the damage to the filter layer.

In the above scheme, the first bonding layer can directly penetrate through the first isolation layer, and a yielding space for the first bonding layer to penetrate through can also be formed in the first isolation layer. Because the aperture on the first isolation layer is not lower than the surface aperture of the filter layer under the general condition, the permeability of the first isolation layer to thermosetting glue can not produce a blocking effect, and the strength of the first isolation layer can play a supporting role on the filter layer.

The first isolation layer is internally provided with a hollow area, and the projection area of the hollow area on the plane of the liquid inlet guide screen occupies 40-95% of the effective area of the liquid inlet guide screen.

Preferably, the thickness of the first isolation layer is 0.1-1 mm.

In the above technical solution, the effective area refers to that liquid flows through the liquid inlet channel during the filtration process and permeates into the filter layer on one side or both sides during the flow process. After the support layer is added, the support layer is substantially located in the liquid inlet channel, and although in general, the support layer is made of a material such as non-woven fabric with larger pores so as to reduce the influence on the liquid flow, the influence still exists. The hollow area in the design part of the supporting layer can help to reduce the resistance in the liquid inlet process and improve the filtering effect.

The application also designs a preparation method of the vertical flow filter element, which comprises the following steps:

s1, directly or indirectly combining a liquid inlet guide screen with a filter layer;

s2, attaching thermosetting adhesive to the first liquid inlet hole position on the liquid inlet guide screen, and enabling the thermosetting adhesive to enter the liquid inlet guide screen through negative pressure and diffuse to the filter membrane;

s3, heating the thermosetting adhesive to enable the thermosetting adhesive to permeate the filter layer and solidify;

s4, alternately stacking the filter layer-liquid inlet guide screen-filter layer composite system and the filtrate guide screen, and packaging and fixing the combination through a shell to form the vertical flow filter element.

Preferably, in step S3, while heating, a pressure is applied to the liquid inlet guide screen and the filter layer in opposite directions, so that the liquid inlet guide screen and the filter layer are directly or indirectly attached.

The thermosetting adhesive permeates to the liquid inlet surface side of the filter layer through one side of the liquid inlet guide screen, and the fluidity and the fluid power of the thermosetting adhesive are further provided through heating and negative pressure. The liquid can be permeated into the surface of the filter layer by a certain degree of negative pressure or pressure in the direction perpendicular to the filter layer, and the filtering effect of the filter layer is not obviously influenced. Under the heating state, the viscosity of the first bonding layer is reduced, gaps between the filter layer and the liquid inlet guide screen mesh can be well sealed, good sealing performance is achieved, and meanwhile, the thermosetting adhesive has good stripping resistance effect after thermosetting.

In the preparation process, filter layers are required to be installed on two sides of the liquid inlet guide screen to form a filter layer-liquid inlet guide screen-filter layer composite system, wherein the filter layers and the liquid inlet guide screen can be directly attached, and a supporting layer can be arranged in the middle of the filter layers and the liquid inlet guide screen to adjust a flow channel and a fixing mode.

After solidification, the composite system of the filter layer-the liquid inlet guide screen is attached to the filtrate guide screen, the filter layer and the filtrate guide screen can be connected through an elastic system positioned on the surface of the filtrate guide screen, and the filter layer and the filtrate guide screen can be connected in a sealing manner only through elastic extrusion, and can be bonded in an auxiliary manner by adopting a viscose system with certain viscosity.

The vertical flow filter element prepared by the preparation process has good integrity, sealing performance and filtering effect.

In summary, this application is anticipated is providing a structure of membrane package with cellulose-based filter layer, and this membrane package bonds the feed liquor level and the feed liquor water conservancy diversion screen cloth of filter layer through having the thermosetting glue of low mobility under the high temperature, low temperature, makes thermosetting glue can permeate the filter layer betterly, and then realizes bonding and sealing, and overall structure is stable, and the leakproofness is good, has outstanding positive influence to performance and the yields that improve the membrane package.

Drawings

FIG. 1 is an SEM image of the filter layer of example 1 at 10000 times enlarged in cross section, wherein the upper side is the liquid inlet surface and the lower side is the liquid outlet surface

FIG. 2 is a SEM image at 1000 Xmagnification of the inlet surface of the filter layer of example 1;

FIG. 3 is a schematic view showing the overall appearance of the filter element of example 1;

fig. 4 is a schematic structural diagram of the inlet flow guiding screen, the filter layer and the filtrate flow guiding screen in example 1.

In the figure, 1, a liquid inlet diversion screen; 11. a first liquid inlet hole; 12. a first filtrate aperture; 2. a filtrate diversion screen; 21. a second liquid inlet hole; 22. a second filtrate aperture; 3. a filter layer; 33. a third liquid inlet hole; 34. a third filtrate aperture; 4. a first support layer; 41. hollow areas; 5. a first adhesive layer; 6. a second support layer; 7. and a second adhesive layer.

Detailed Description

The following description of the embodiments of the present invention will be made apparent and fully in view of the accompanying drawings, in which some, but not all embodiments of the invention are shown. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.

In the following examples, the SEM average pore size of the liquid inlet or outlet surface of the filter layer, or the SEM average pore size of the cross section, can be measured by computer software (e.g. Matlab, NIS-Elements, etc.) or manually after the morphology of the membrane structure is characterized by using a scanning electron microscope, and calculated accordingly. In practice, the surface of the film can be characterized by electron microscopy to obtain a corresponding SEM image, and a certain area, such as 1 μm, can be selected because the pores on the surface of the film are substantially uniform ² (1 μm by 1 μm) or 25 μm ² (5 μm by 5 μm), measuring the pore diameters of all the pores on the specific area by corresponding computer software or manually according to the actual condition, and calculating to obtain the average pore diameter of the pores on the surface; of course, the person skilled in the art can also obtain the above parameters by other measuring means, which are only used as reference.

In the following examples, the adhesion between the filter layer and the inlet guide screen may be characterized by the following method: after the filter layer and the liquid inlet guide screen are bonded, the positions of the edges of the filter layer and the first bonding layer are clamped by rubber head tweezers at room temperature, and the filter layer is pulled to one side far away from the liquid inlet guide screen in the direction perpendicular to the filter layer until the filter layer and the liquid inlet guide screen are separated or the filter layer is completely broken, and only the part with the edge free of tilting is left. In general, since the cohesion of the filter layer is generally less than the cohesion between the filter layer and the screen during normal bonding, the area of the residue can be used to measure the tightness of the bond between the filter layer and the inlet flow screen.

The viscosities of the first and second tie layers were measured by a coaxial dual cylinder rotational viscometer.

The roughness of the filter layer was measured by a commercially available roughness tester.

The integrity test is carried out by a seed air diffusion flow test, and the specific test method is as follows:

the prepared filter element was wetted with water, the liquid inlet end of the element was connected to compressed air, and a pressure of 0.1mPa was applied to the liquid inlet end, and then the air flow rate was measured at the liquid outlet end to evaluate the integrity. The smaller the air flow, the better the integrity of the film package.

In the following examples, the filter elements were each prepared with a membrane area of 0.46m ² And (3) packaging the filtering membrane, wherein in the case, the qualified product is obtained when the liquid outlet end has the air flow rate of less than or equal to 50mL/min, and the lower the air flow rate is, the better the integrity is.

Example 1, a vertical flow filter element, referring to fig. 1-4, can be used alone or in combination, having an overall rectangular membrane packet shape, comprising the following components:

feed liquor water conservancy diversion screen cloth 1: the liquid inlet guide screen 1 is rectangular, and the two opposite sides of the liquid inlet guide screen 1 are provided with a first liquid inlet hole 11 and a first filtrate hole 12, and the first liquid inlet holes 11 and the first filtrate holes 12 on the same side of the liquid inlet guide screen 1 are alternately arranged, and in general, the aperture of the first liquid inlet hole 11 is larger than that of the first filtrate hole 12.

The filtrate guiding screen 2 is rectangular, and second liquid inlet holes 21 and second filtrate holes 22 are formed in two opposite sides of the filtrate guiding screen 2, wherein the first liquid inlet holes 11 and the second liquid inlet holes 21 are aligned in the direction perpendicular to the planes of the liquid inlet guiding screen 1 and the filtrate guiding screen 2 to form liquid inlet ends of the filter element;

the feed water diversion screen 1 and the filtrate diversion screen 2 have the following parameters:

average distance between two adjacent wires is 490 μm

A filter layer 3 is arranged between any adjacent liquid inlet guide screen 1 and filtrate guide screen 2, the filter layer 3 is provided with a liquid inlet surface 31 and a liquid outlet surface 32, wherein the liquid inlet surface 31 faces the liquid inlet guide screen 1, and the liquid outlet surface 32 faces the filtrate guide screen 2. A liquid inlet flow channel is formed between liquid inlet surfaces 31 of the adjacent filter layers 3, and a filtrate flow channel is formed between liquid outlet surfaces 32 of the adjacent filter layers 3; the filter layer 3 has third liquid inlet holes 33 aligned with the first liquid inlet holes 11 and the second liquid inlet holes 21 and third filtrate holes 34 aligned with the first filtrate holes 12 and the second filtrate holes 22.

In this example, the filter layer was a single-layer regenerable cellulose filter membrane, the preparation of which can be performed with reference to CN115770490a, and the prepared filter membrane is shown in fig. 1, and has the following parameters:

thickness of 43.1 μm

The roughness of the liquid inlet surface is 0.29nm

The area ratio of the holes on the liquid inlet surface is 47 percent

PMI pore diameter 20.1nm

In this embodiment, a first supporting layer 4 is disposed between the liquid inlet guide screen 1 and the liquid inlet surface 31 of the filtering layer 3, the first supporting layer 4 is a non-woven fabric structure, and a first through hole aligned and communicated with the first liquid inlet hole 11 and the second liquid inlet hole 21 and a second through hole aligned and communicated with the first filtrate hole 12 and the second filtrate hole 22 are formed on the first supporting layer 4.

A first adhesive layer 5 is further disposed between the liquid inlet guiding screen 1 and the filter layer 3, in this embodiment, the first adhesive layer 5 is made of epoxy resin, and can penetrate through the first supporting layer 4 and seal and isolate the first filtrate hole 12 and the filtrate channel.

There is second supporting layer 6 between filter layer 3 and filtrate water conservancy diversion screen cloth 2, and first supporting layer and second supporting layer 6 are the non-woven fabrics, are equipped with fretwork district 41 in the middle of the first supporting layer 4, and fretwork district 41 accounts for 90% of the area of first supporting layer 4 for improve the filter effect.

A second adhesive layer 7 is further arranged between the filter layer 3 and the filtrate guiding screen 2, and the second adhesive layer 7 is silica gel in this embodiment, the viscosity of the second adhesive layer 7 is 20000cps, and the second adhesive layer is a permeable second support layer 6, and seals and isolates the second liquid inlet 21 and the liquid inlet channel.

The preparation method of the vertical flow filter element in the embodiment comprises the following steps:

s1, paving a liquid inlet guide screen;

s2, paving the first supporting layer and the filter layer on the liquid inlet guide screen on which the first bonding layer is paved, aligning the third liquid inlet hole with the first liquid inlet hole, aligning the third filtrate hole with the first filtrate hole, applying thermosetting glue on the first filtrate hole, and applying negative pressure on the first liquid inlet hole to enable glue solution to permeate into the liquid inlet guide screen;

s3, heating the system to 60 ℃, enabling the glue solution to permeate into the liquid inlet surface of the filter layer along the liquid inlet guide screen through the first support layer, and diffusing the glue solution to the periphery around the first liquid inlet hole at the same time so as to form a glue ring sealed at the periphery of the first liquid inlet hole; then keeping the temperature to cure the first bonding layer for 24 hours to obtain a liquid inlet unit after curing; in the above process, a certain pressure is moderately applied in the thickness direction to compress the material;

s4, paving a second supporting layer on the filtrate diversion screen, paving a second bonding layer at a position surrounding the second liquid inlet hole, alternately stacking the second bonding layer and the liquid inlet unit, and then forming an elastic sealing structure through extrusion.

In this embodiment, after the membrane package is mounted on a specific fixture, the stock solution enters a first liquid inlet hole through the liquid inlet end and enters the liquid inlet flow channel through the first liquid inlet hole. In the flowing process of the liquid inlet flow channel, the preservation liquid or gas in the membrane package can be discharged through other liquid inlet ends to generate reflux liquid as shown in fig. 3-4, then the liquid inlet ends without liquid inlet are subjected to sealing treatment, the liquid enters the filtrate flow channel through the filter membrane and is discharged through the liquid outlet ends to obtain filtrate, and in the process, viruses can be trapped by the filter membrane, so that the virus removal effect of the membrane package is realized.

In an example, the viscosity of the first adhesive layer at room temperature was 240cps, and after heating to 60 ℃ during the heating process of step S3, the viscosity of the first adhesive layer was measured as 23261cps (three measurements averaged).

In this and subsequent examples, the pore shape of the filter membrane inlet surface was irregular and the depth region was not apparent, so that it was actually difficult to determine the exact average pore diameter, but it was apparent that the pore diameter of the surface was significantly greater than 500 nm.

Example 2 the parameters shown in table 2 were obtained by changing the first adhesive layer material according to the filter layer based on example 1.

TABLE 2

In this embodiment, the thermosetting adhesives are epoxy resins, and their properties are different according to the substituent groups and the molecular weights, for example, changing an intermediate monomer having a larger conjugated system (such as a biphenyl structure or a condensed ring structure) as epoxy may increase the thermosetting temperature of the first adhesive layer, increasing the molecular weight of the epoxy resin may increase the viscosity of the epoxy resin, and so on.

For parameter adjustment of the filter layer, reference can be made to CN115770490a to form filter membranes with different meniscus void fractions and surface roughness.

In example 1 and example 2, the formula y=k is followed ₁ /ln (2-x), calculated k ₁ The values and their corresponding experimental results are shown in table 3. Wherein y is the viscosity of the first bonding layer at the thermosetting temperature, and x is the area ratio of holes on one side of the filter layer facing the liquid inlet guide screen.

TABLE 3 Table 3

Example 3 on the basis of example 1, a different first tie layer was further adapted, as specifically shown in table 4.

TABLE 4 Table 4

According to the formula y=k ₁ /ln (2-x), calculated k ₁ Values.

According to formula y ₂ ＝k ₂ d/l, calculated k ₂ Values. Wherein d is the diameter of a monofilament of the liquid inlet guide screen, l is the average distance between two adjacent filaments in the same direction in the liquid inlet guide screen, and y ₂ Is the viscosity of the first adhesive layer at room temperature.

k ₁ 、k ₂ The values and the results of the related experiments are shown in Table 5.

TABLE 5

Example 4 based on example 1, a bilayer membrane structure was used as the filter layer, wherein the parameters of the filter layer are shown in table 6.

TABLE 6

For example 4, k ₁ The values and the results of the related experiments are shown in Table 7.

TABLE 7

Through the experimental data of examples 1 to 4, it was possible to smoothly achieve the adhesion of the filter membrane in the selection of the first adhesive layer, which is generally required to have a viscosity of less than 1000cps at the thermosetting temperature. The adhesion performance is similar in terms of single-layer and multi-layer filters, but when the viscosity exceeds 1000cps at the curing temperature, the adhesion between the glue and the filter layer is poor, which can adversely affect the integrity of the membrane package in addition to the adhesion between the filter and the screen.

For viscosity at the heat set temperature of the first tie layer, the formula y=k is compared ₁ As can be seen in/ln (2-x), when k ₁ When the parameter selection range is 75-300 cps, the adhesive has better bonding and sealing effects compared with the content outside the range. If the viscosity is too low (examples 3-8), the spreading area of the first adhesive layer along the plane in the construction process is too large, and the filtration area of the membrane package is affected. On the other hand, too high a viscosity (examples 3-2, 3-4, etc.) results in insufficient adhesion to adequately bond the filter layer and the inlet flow screen, and thus in a decrease in the integrity of the membrane package. In addition, on the basis of the above, when k ₁ When the value range is 100-250 cps, the integrity of the film package is better than other schemes, and the film package is a more preferable technical scheme.

Example 5, further replacing different screens on the basis of example 1, the specific inlet guide screen parameters are shown in table 8.

TABLE 8

In corresponding example 5, the calculated k ₂ The values and the spreading of the first adhesive layer are shown in table 9.

TABLE 9

For the viscosity of the first adhesive layer at room temperature, reference is made toY is as follows ₂ ＝k ₂ d/l can be calculated to obtain the applicable range k ₂ The value of (2) is preferably 25000 to 150000cps. When the viscosity is too high, the adhesive is laid on the liquid inlet guide screen too slowly, and uneven areas are easily formed on the surface of the first adhesive layer, so that the integrity of the film package is affected. Too low viscosity can cause too large a laying range of the first bonding layer on the liquid inlet guide screen, so that the bonding with the filter layer is difficult to occur, and meanwhile, the effective filtering area is reduced.

The above embodiments are only preferred embodiments of the present invention, and the scope of the present invention is not limited thereto, but any insubstantial changes and substitutions made by those skilled in the art on the basis of the present invention are intended to be within the scope of the present invention as claimed.

Claims (17)

1. A vertical flow filter element comprising in particular the following components:

the liquid inlet diversion screen is provided with at least one first liquid inlet hole and at least one first filtrate hole;

the filtrate diversion screen is provided with at least one second liquid inlet hole and at least one second filtrate hole;

the filter layer is arranged between the liquid inlet guide screen and the filtrate guide screen and is provided with a liquid inlet surface and a liquid outlet surface;

the liquid inlet guide screen meshes and the filtrate guide screen meshes are alternately stacked, and a filter layer is arranged between each two adjacent liquid inlet guide screen meshes and filtrate guide screen meshes; the liquid inlet surface of the filter layer faces the liquid inlet guide screen adjacent to the liquid inlet guide screen, the liquid outlet surface of the filter layer faces the filtrate guide screen adjacent to the liquid inlet guide screen, a liquid inlet flow channel is formed between the liquid inlet surfaces of the adjacent filter layers, and a filtrate flow channel is formed between the liquid outlet surfaces of the adjacent filter layers;

it is characterized in that the method comprises the steps of,

a first bonding layer is arranged between the filter layer and the liquid inlet guide screen and used for sealing and isolating a first filtrate hole and a filtrate flow passage, and the liquid inlet surface of the filter layer is provided with an SEM average pore diameter not less than 200 nm; the first bonding layer is a thermosetting adhesive, and has a thermosetting temperature not higher than 150 ℃; the first adhesive layer has an adhesion of not less than 10000cps at room temperature, and the first adhesive layer has at least one temperature point when heated to 45-150deg.C so that the first adhesive layer has an adhesion of not more than 1000cps.

2. A vertical flow filter element according to claim 1 wherein the first bonding layer has at least one temperature point in the range of 60 to 120 ℃ such that the viscosity of the first bonding layer is 100 to 1000cps.

3. A vertical flow filter element according to claim 2 wherein said adhesive layer has at least one temperature in the range of 60 to 120 ℃ and the viscosity and the layer inlet level pore area ratio satisfy the following relationship: y=k ₁ And/ln (2-x), wherein y is the viscosity of the first adhesive layer at the thermosetting temperature, x is the hole area ratio of the side of the filter layer facing the liquid inlet guide screen, and k ₁ Is constant and ranges from 75 to 300cps.

4. A vertical flow filter element according to claim 3, wherein the filter layer has a void area ratio in the range of 30-60% on the side facing the inlet flow screen.

5. A vertical flow filter element according to claim 3, wherein the liquid inlet side of the filter layer has a surface tension in the range 50-80 mN/m.

6. A vertical flow filter element according to claim 3, wherein the liquid outlet face of the filter layer has a roughness of 0.1-0.5 μm.

7. A vertical flow filter element according to claim 1, wherein the parameters associated with the inlet guide screen and the viscosity of the thermoset glue at room temperature have the following relationship: y is ₂ ＝k ₂ d/l, whereinD is the diameter of a monofilament of the liquid inlet guide screen, l is the average distance between two adjacent filaments in the same direction in the liquid inlet guide screen, and k ₂ Is a parameter, and ranges from 25000 to 150000cps.

8. The vertical flow filter element of claim 7, wherein the inlet guide screen has a monofilament diameter in the range of 50 to 500 μm.

9. The vertical flow filter element of claim 7, wherein the average distance between two wires in the same direction in the feed-liquid diversion screen is in the range of 50-500 μm.

10. The vertical flow filter element of claim 7, wherein the feed water diversion screen has a pore size of 200-800 μm.

11. The vertical flow filter element of claim 7, wherein the feed water diversion screen has a porosity of 25-50%.

12. The vertical flow filter element of claim 1, wherein a first barrier is provided between the filter layer and the inlet flow screen, and the thermosetting glue passes through the first barrier.

13. The vertical flow filter element of claim 12, wherein the first separator layer has a hollow region therein, and wherein the projected area of the hollow region on the plane of the liquid inlet guide screen is 40-95% of the effective area of the liquid inlet guide screen.

14. A vertical flow filter element according to claim 12, wherein the thickness of the first spacer layer is 0.1-1 mm.

15. A vertical flow filter element according to claim 1, wherein the filter layer is a cellulose filter layer.

16. A method of producing a vertical flow filter element as claimed in any one of claims 1 to 15, comprising at least the steps of:

s1, directly or indirectly combining a liquid inlet guide screen with a filter layer;

s2, attaching thermosetting adhesive to the first liquid inlet hole position on the liquid inlet guide screen, and enabling the thermosetting adhesive to enter the liquid inlet guide screen through negative pressure and diffuse to the filter membrane;

s3, heating the thermosetting adhesive to enable the thermosetting adhesive to permeate the filter layer and solidify;

s4, alternately stacking the filter layer-liquid inlet guide screen-filter layer composite system and the filtrate guide screen, and packaging and fixing the combination through a shell to form the vertical flow filter element.

17. The method of producing a vertical flow filter element according to claim 16, wherein in step S3, the inlet guide screen and the filter layer are directly or indirectly bonded by applying opposing pressure to each other while heating.