CN103966887B - A method for reducing the difference between two sides of paper and the paper prepared therefrom - Google Patents

Abstract

The invention provides a method for reducing the difference between two sides of paper. The paper is designed as a multi-layer fiber layer structure, and each layer is independently prepared and beaten; the pulp enters the paper machine with multiple independent flow channels, and is stacked and formed at the same time in the forming area. The content of fine fibers with a diameter of less than 1 μm in I is higher than that of other layers of slurry, preferably 5-10%. The present invention also provides the low-difference paper prepared by the above method, especially the low-dual-difference glass fiber paper, and the coalescing filter element containing the low-difference glass fiber paper. The glass fiber paper with low two-sided difference provided by the invention has uniform fiber density in the thickness direction of the paper, and can significantly improve the efficiency and separation capacity of the coalescing filter element.

Description

A method for reducing the difference between two sides of paper and the paper prepared therefrom

technical field

The invention belongs to the field of papermaking, and in particular relates to a method for reducing double-sidedness of paper and the prepared paper with low double-sidedness.

Background technique

During the wet forming process of papermaking, due to the action of vacuum suction, on the side close to the paper forming wire, the fine fibers are easily lost along the water flow through the pores of the forming wire, so that the paper sheet on the side of the forming wire The fine fiber content is lower than the other side, resulting in obvious two-sidedness phenomenon, that is, there is a difference in the degree of fiber uniformity in the thickness direction of the paper sheet. For paper with high fine fiber content, such as high-precision filter paper, battery separator, etc., this two-sided difference is more obvious. This has had an important impact on the application of high-performance paper in the fields of filtration and separation.

For example, coalescing filters used for gas-liquid separation and liquid-liquid separation usually use multi-layer wound glass fiber filter paper as filter elements. The liquid particles to be removed can be intercepted by the fine diameter glass fibers by diameter interception, inertial impact or Brownian motion. Once the coalesced droplets on the fibers become large enough, they are separated and collected by falling from the surface of the fibrous filter paper through the viscous forces flowing through the filter paper and the gravity of the droplets.

The above-mentioned glass fiber filter paper is made of glass fiber by wet papermaking. Generally speaking, glass fibers are divided into glass fiber chopped strands (manufactured by melt drawing method, fiber diameter greater than or equal to 6 μm) and glass wool fibers (manufactured by flame blowing method, average fiber diameter is less than 3 μm) according to fiber diameter; Among the cotton fibers, those with an average fiber diameter greater than or equal to 1 μm are called coarse glass wool fibers, and those with an average fiber diameter of less than 1 μm are called fine glass wool fibers. When the paper sheet is formed, on the side close to the paper forming wire, the tiny fine glass wool fibers are easily lost by the vacuum suction force, so that the fine glass wool fiber content of the paper sheet on the forming wire side is lower than that of the other side. One side, resulting in obvious two-sided difference phenomenon. For coalescing filter elements with several to dozens of layers of glass fiber filter paper, if each glass fiber filter paper has two-sided differences, as the number of filter paper layers increases, the fiber uniformity in the thickness direction of the paper will decrease. The difference will be enlarged, resulting in the inability of the coalescing ability of the fluid from the inflow surface to the outflow surface to be consistent all the time, affecting the excellent coalescence and separation efficiency of the filter element in a limited space.

Therefore, the high-precision filtration represented by the coalescing filter element puts forward high requirements on the uniformity of the paper thickness direction. However, the disclosed technical documents rarely pay attention to the uniformity of the thickness direction of the paper sheet and the method for eliminating the difference between the two sides of the paper.

Chinese Utility Model Patent (notification number CN203284679U, date of announcement on November 13, 2013) discloses a top wire former capable of adjusting the difference between the two sides of the paper. Adjust the upward and downward dehydration of the paper sheet by setting independent top wire suction box and bottom wire suction box, thereby improving the difference in appearance on both sides of the paper sheet, but there are still differences in the fiber composition in the thickness direction of the entire paper sheet, uniform Sexual issues were not resolved.

Contents of the invention

In view of the above problems, an object of the present invention is to provide a method for reducing the difference between the two sides of the paper, so that the fiber composition of the paper, especially the glass fiber filter paper, is more uniform in the thickness direction of the paper; knot and breakaway properties.

In order to realize the foregoing invention object, the present invention adopts following technical scheme:

A method to reduce the difference between two sides of paper. The paper is designed as a multi-layer fiber layer structure, and each layer is independently prepared and beaten; the pulp enters a paper machine with multiple independent flow channels, and is laminated and formed in the forming area at the same time. The content of fine fibers with a diameter of less than 1 μm in the slurry I next to the flow channel of the forming wire is higher than that of the other layers of slurry.

Preferably, the content of the fine fiber in the slurry I is 5-10% higher than the content of the fine glass fiber in the other layers of slurry.

Preferably, before papermaking, the rectification of the slurry is also included, so that the slurry presents a high-strength micro-turbulent flow state.

Preferably, the fiber types of each layer of slurry are the same; more preferably, except for the slurry I, the fiber composition and weight ratio of each layer of slurry are the same.

As a preferred embodiment of the present invention, the fiber composition of each layer of slurry is alkali-free glass fiber chopped strands, organic binder and glass wool fibers containing fine glass wool fibers with a diameter less than 1 μm, and the slurry I The content of medium and fine glass wool fibers is higher than that of the fine glass wool fibers of other layers of slurry, and is more preferably 5-10% higher.

Preferably, the glass wool fibers further include coarse glass wool fibers with a diameter greater than or equal to 1 μm but less than 3 μm.

Preferably, the glass wool fibers are selected from borate glass wool fibers or alkali-free glass wool fibers. ;

In the above-mentioned preferred embodiment, more preferably, during stock preparation, based on the total dry weight of each layer of fibers, the weight percentages of various fibers are:

15-25% of alkali-free glass fiber chopped strands, 0-65% of coarse glass wool fibers, 10-65% of fine glass wool fibers, and 5-10% of organic binders; wherein, the fine glass wool in the slurry I The fiber content is higher than the fine glass wool fiber content of other layers of slurry, and is more preferably 5-10% higher.

Preferably, the formulations of the other layers of slurry are the same.

Further preferably, when preparing pulp, based on the total dry weight of each layer of fibers, the weight percentages of various fibers are:

15-25% of alkali-free glass fiber chopped strands, 40-60% of coarse glass wool fibers, 15-30% of fine glass wool fibers, and 5-10% of organic binders; wherein, the fine glass wool in the slurry I The fiber content is higher than the fine glass wool fiber content of other layers of slurry, and is more preferably 5-10% higher.

Preferably, the formulations of the other layers of slurry are the same.

Another object of the present invention is to provide a paper with low two-sidedness, having a multilayer fibrous layer structure, prepared by the above method, wherein the first layer is formed by the operation of said slurry I next to the forming wire.

The present invention also provides a glass fiber paper with low two-sided difference, which has a multi-layer fiber layer structure, wherein the first layer is formed by the slurry I entering the flow channel next to the forming wire; the fiber composition of each layer of slurry is free Alkali glass fiber chopped strands, organic binder, and glass wool fibers containing fine glass wool fibers with a diameter less than 1 μm; the content of fine glass wool fibers in the slurry I is higher than that of the fine glass wool fibers of other layers of slurry The content is high, more preferably 5 to 10%.

Preferably, the glass wool fibers further include coarse glass wool fibers with a diameter greater than or equal to 1 μm but less than 3 μm.

Preferably, the glass wool fibers are selected from borate glass wool fibers or alkali-free glass wool fibers.

In the above-mentioned preferred embodiment, more preferably, during pulp preparation, based on the total dry weight of fibers of each layer, the weight percentages of various fibers are:

15-25% of alkali-free glass fiber chopped strands, 0-65% of coarse glass wool fibers, 10-65% of fine glass wool fibers, and 5-10% of organic binders; wherein, the fine glass wool in the slurry I The fiber content is higher than the fine glass wool fiber content of other layers of slurry, and is more preferably 5-10% higher.

Preferably, the formulations of the other layers of slurry are the same.

Further preferably, when preparing pulp, based on the total dry weight of each layer of fibers, the weight percentages of various fibers are:

15-25% of alkali-free glass fiber chopped strands, 40-60% of coarse glass wool fibers, 15-30% of fine glass wool fibers, and 5-10% of organic binders; The content is higher than the fine glass wool fiber content of other layers of slurry, and is more preferably 5-10% higher.

Preferably, the formulations of the other layers of slurry are the same.

In the preferred embodiment above, more preferably, the first layer accounts for 15-30% of the total weight of the low double-sided difference glass fiber paper, and more preferably 20-25%.

Yet another object of the present invention is to provide the above-mentioned application of the glass fiber paper with low two-sided difference in the preparation of a filter element; preferably, the filter element is a coalescing filter element.

The present invention also provides a coalescing filter element, comprising the above-mentioned glass fiber paper with low two-sided difference.

The organic binder in the present invention can be selected from commonly used ones in this field, such as acrylic resin, phenolic resin and the like.

The low two-sidedness paper and the low two-sidedness glass fiber paper of the present invention, before each layer is formed, the pulp is diluted to a conventional solid weight percentage concentration; step. In order to adjust the air permeability of the paper, the glass fiber paper with low two-sided difference of the present invention is preferably added with coarse glass wool fibers having a diameter larger than that of the fine glass wool fibers.

For the paper sheet using the traditional wet papermaking method, when the paper sheet is formed, the side close to the paper forming wire is subjected to the suction force of vacuum dehydration, and the tiny fibers with a diameter of less than 1 μm are easy to pass through along the water flow. The pores of the forming wire are lost so that the fine fiber content of the sheet is lower on the forming wire side than on the other side. What Fig. 1 shows is exactly in the prior art, the paper sheet fiber distribution schematic diagram of difference on both sides of the forming wire, wherein 1 represents the formed paper sheet, 2 represents fine fibers, 3 represents the forming wire. The density of the fine fibers 2 on the side close to the forming wire 3 is lower than that on the side away from the forming wire. The common coalescing filter element is obtained by winding the double-sided glass fiber paper prepared by the above-mentioned method in the prior art. Fig. 2 shows a schematic structural view of the filter element, wherein 4 indicates an inflow surface, and 5 indicates an outflow surface. It can be seen from Figure 2 that during the process of the fluid from the inflow surface 4 to the outflow surface 5, due to the uneven density of the fibers, the coalescence ability of the filter paper to the fluid will fluctuate up and down, which will affect the separation ability of the filter element.

The present invention adopts a multi-layer structure in the design of the paper, each layer is independently prepared and beaten, and realizes multi-layer papermaking and dehydration at the same time through the multi-channel papermaking forming technology; The slurry in the runner increases a certain proportion of fine fibers. In this way, the higher proportion of fine fibers in the slurry I can make up for the loss of fine fibers during dehydration, and the fiber composition between the layers is close to uniform, so that the proportion of fine fibers in the thickness direction of the paper sheet after forming will not change greatly. Thereby reducing the difference between the two sides of the paper. The schematic diagram of the fiber distribution of the low two-sidedness paper prepared by the method of the present invention is shown in Figure 3, wherein 1 represents the formed paper, 2 represents the fine fibers, and 3 represents the forming wire. In the thickness direction of the paper sheet 1, the distribution uniformity of the fine fibers 2 has been greatly improved. The glass fiber paper with low two-sided difference prepared by the method of the present invention, the structural schematic diagram of the coalescing filter element obtained by multi-layer winding, as shown in Figure 4, wherein 4 indicates the inflow surface, and 5 indicates the outflow surface. It can be seen from Fig. 4 that the density of the fibers is basically consistent during the process of the fluid from the inflow surface 4 to the outflow surface 5. Therefore, the fluctuation of the coalescence ability of the common coalescing filter element in the prior art is overcome, and the filter element is improved. separation ability. The results of Test Example 1 show that after 4000 hours of operation of the air compressor using the ordinary coalescing filter element, the lubricating oil level drops below the warning line, and the air compressor cannot operate safely and stably, and the lubricating oil needs to be added again. However, the low two-sidedness glass fiber paper manufactured by the method of the present invention is used to make a coalescing filter of the same specification and size. Under the same conditions, the working time of the air compressor can reach 5000h, reducing the frequency of lubricating oil addition. It shows that the low two-sidedness glass fiber paper manufactured by the method of the present invention effectively improves the coalescence efficiency of lubricating oil droplets in compressed air.

The multi-channel paper machine used in the method of the present invention can adopt the structure disclosed in the invention patent application (publication number CN103137931A, publication date June 5, 2013). Taking the three-channel inclined-wire paper machine as an example, the structural diagram is shown in Figure 5. Among them, A is the pulp distributor of the inclined wire paper machine. The pulp distributor A is divided into three independent flow channels, which are represented by 1, 2 and 3 respectively, and the pulp will not mix when entering it. B is the rectification area of the paper machine, which is also divided into three flow channels, which match the flow channels 1 and 2 of the pulp distributor A. The function of the rectification area B is to rectify the slurry from the slurry distributor A to produce a high-strength micro-turbulent flow state without eddy currents, so that the flow state of the slurry is stable, so as to ensure that the three-layer slurry is formed. No mixing takes place and good homogeneity is obtained. After passing through the rectification zone B, the pulp reaches the dewatering forming zone C of the inclined wire paper machine, and the three-layer pulp from the rectifying zone B is dehydrated and formed at the dewatering forming zone C by vacuum dehydration. The slurry I of the present invention enters the flow channel 3 of the slurry distributor A, and the slurry of other layers enters the flow channel 1 or 2 respectively. In this way, the pulp I is formed close to the forming wire, and its relatively high fine fiber content makes up for the loss of fine fibers during dehydration, so that the fiber distribution of the paper in the thickness direction is uniform, and the two-sided difference is reduced.

Description of drawings

Below, describe embodiment of the present invention in detail in conjunction with accompanying drawing, wherein:

Figure 1 shows a schematic diagram of the fiber distribution of a double-sided paper sheet on a forming wire in the prior art, wherein 1 indicates a formed double-sided paper sheet, 2 indicates fine fibers, and 3 indicates a forming wire.

Figure 2 shows a schematic structural view of a coalescing filter element made of glass fiber paper with two-sided difference, in which 4 indicates the inflow surface, 5 indicates the outflow surface, and the direction of the arrow indicates the flow method of the fluid.

Figure 3 shows the fiber distribution diagram of the paper sheet with low double-sided difference on the forming wire prepared by the method of the present invention, wherein 1 represents the formed low double-sidedness paper sheet, 2 represents fine fibers, and 3 represents the forming wire.

Figure 4 shows a schematic structural view of a coalescing filter element made of glass fiber paper with low two-sided difference, in which 4 indicates the inflow surface, 5 indicates the outflow surface, and the direction of the arrow indicates the flow method of the fluid.

Figure 5 shows a schematic diagram of the structure of the three-channel inclined wire paper machine, where A represents the pulp distributor of the inclined wire paper machine, 1, 2, and 3 represent the three independent flow channels of the pulp distributor A, B represents the rectification area, and C Indicates the forming area, and D indicates the formed multilayer paper.

detailed description

The present invention will be described below with reference to specific examples. Those skilled in the art can understand that these examples are only used to illustrate the present invention and do not limit the scope of the present invention in any way.

The experimental methods in the following examples are conventional methods unless otherwise specified. The medicinal raw materials, reagent materials, etc. used in the following examples are all commercially available products unless otherwise specified.

Among them, the diameter of the alkali-free glass fiber chopped strands is 6 μm;

The average diameter of borate coarse glass wool fibers is 2.6μm, and the grade is 475;

The average diameter of alkali-free coarse glass wool fibers is 2.6 μm;

The average diameter of borate fine glass wool fibers is 0.8μm, and the grade is 475;

The average diameter of alkali-free fine glass wool fibers is 0.8 μm;

The softwood fiber is flash-dried kraft softwood pulp;

The hardwood fiber is parrot eucalyptus hardwood pulp;

The polyester fiber is Jinsilu brand PET fiber, with a fineness of 1.67dtex and a length of 3mm;

Acrylic resin A is produced by Guangzhou Wuwei Special Material Development Co., Ltd., brand G408;

Acrylic resin B is produced by Guangzhou Wuwei Special Material Development Co., Ltd., brand PR3647;

Fluorocarbon resin is produced by Japan Daikin Fluorochemical Co., Ltd., brand TG580.

Embodiment 1 A kind of glass fiber paper with low two-sided difference

A glass fiber paper with low two-sidedness, with a basis weight of 85g/m ² , consisting of two fiber layers, prepared by the following method:

1. Each layer is prepared and flowed separately

The raw materials are mixed with water according to the formula shown in Table 1, dispersed and diluted to a solid weight percent concentration of 0.8%, to obtain slurry I and slurry II, wherein the content of borate fine glass wool fibers in slurry I is higher than that of slurry 7.5% more II;

2. Copy into shape

Slurry I and II are respectively sent to the multi-channel inclined wire paper machine, wherein the slurry I enters the flow channel close to the forming area, and the two layers are simultaneously sheeted and formed, and after dehydration treatment, sizing, drying, and curling, the target paper is obtained. product. The first layer of the glass fiber paper with low double-sided difference is formed by slurry I, and the second layer is formed by slurry II.

Embodiment 2 A kind of glass fiber paper with low two-sided difference

A glass fiber paper with low two-sidedness, with a basis weight of 85g/m ² , consisting of 3 fiber layers, prepared by the following method:

1. Each layer is prepared and flowed separately

The raw material is mixed with water according to the formula shown in Table 1, dispersed, diluted to a solid weight percent concentration of 0.67%, to obtain slurry I, slurry II and slurry III, wherein the borate fine glass wool fiber in slurry I Content is 7.5% more than slurry II and slurry III;

2. Copy into shape

Slurries I, II, and III are sent to the multi-channel inclined-wire paper machine respectively, and the slurry I enters the flow channel close to the forming area, and the three layers are simultaneously copied and formed. After dehydration treatment, sizing, drying, and curling, that is get the target product. For the glass fiber paper with low two-sided difference, the first layer is formed by slurry I, the second layer is formed by slurry II, and the third layer is formed by slurry III.

Embodiment 3 A kind of glass fiber paper with low two-sided difference

A glass fiber paper with low two-sidedness, with a basis weight of 85g/m ² , consisting of 3 fiber layers, prepared by the following method:

1. Each layer is prepared and flowed separately

Prepare each raw material according to the formula shown in Table 1, then mix with water, disperse, and dilute to a solid weight percentage concentration of 0.67%, to obtain slurry I, slurry II and slurry III, wherein the alkali-free fine glass wool in slurry I The fiber content is 5% more than pulp II and pulp III;

2. Copy into shape

Slurries I, II, and III are sent to the multi-channel inclined-wire paper machine respectively, and the slurry I enters the flow channel close to the forming area, and the three layers are simultaneously copied and formed. After dehydration treatment, sizing, drying, and curling, that is get the target product. For the glass fiber paper with low two-sided difference, the first layer is formed by slurry I, the second layer is formed by slurry II, and the third layer is formed by slurry III.

Embodiment 4 A kind of glass fiber paper with low two-sided difference

A glass fiber paper with low two-sidedness, with a basis weight of 100g/m ² , consisting of 3 fiber layers, prepared by the following method:

1. Each layer is prepared and flowed separately

Prepare each raw material according to the formula shown in Table 1, then mix with water, disperse, and dilute to a solid weight percentage concentration of 0.67%, to obtain slurry I, slurry II and slurry III, wherein the alkali-free fine glass wool in slurry I The fiber content is 10% more than that of pulp II and pulp III;

2. Copy into shape

Slurries I, II, and III are sent to the multi-channel inclined-wire paper machine respectively, and the slurry I enters the flow channel close to the forming area, and the three layers are simultaneously copied and formed. After dehydration treatment, sizing, drying, and curling, that is get the target product. For the glass fiber paper with low two-sided difference, the first layer is formed by slurry I, the second layer is formed by slurry II, and the third layer is formed by slurry III.

The fiber dry weight formula (weight percent, %) of table 1 embodiment 1-4

Embodiment 5 A kind of engine air filter paper with low double-sided difference

An engine air filter paper with low two-sidedness, with a basis weight of 120g/m ² , composed of 3 fiber layers, prepared by the following method:

1. Each layer is prepared and flowed separately

Prepare each raw material according to the formula shown in Table 2, then mix with water, disperse, and dilute to a solid weight percentage concentration of 2.0%, to obtain slurry I, slurry II and slurry III, wherein the alkali-free fine glass wool in slurry I The fiber content is 5% more than pulp II and pulp III;

2. Copy into shape

Slurries I, II, and III are sent to the multi-channel inclined-wire paper machine respectively, and the slurry I enters the flow channel close to the forming area, and the three layers are formed at the same time. After dehydration treatment, pre-drying, sizing, and post-drying , curly, the target product is obtained. The engine air filter paper with low two-sided difference, the first layer is formed by slurry I, the second layer is formed by slurry II, and the third layer is formed by slurry III.

The fiber dry weight formula (percentage by weight, %) of the fiber dry weight formula of table 2 embodiment 5

Embodiment 6 A coalescing filter element

For the glass fiber paper with low two-sided difference of embodiment 2 and embodiment 3, according to the conventional method in the art, the glass fiber filter paper of embodiment 2 is first wound 10 layers, and then wound 4 layers with the glass fiber filter paper of embodiment 3 to prepare multi-layer Layer-wound coalescing filter element, the filter element is cylindrical, with an inner diameter of Φ110mm, an outer diameter of Φ150mm, and a height of 200mm.

Test Example 1 Coalescing filter element performance test

Test object:

1) Coalescing filter element (hereinafter referred to as "low two-sidedness filter element") prepared from glass fiber paper with low two-sidedness difference according to the present invention: Preparation in Example 6

2) Coalescing filter element (hereinafter referred to as "two-sided filter element") prepared from double-sided glass fiber paper in the prior art: a cylindrical filter element with an inner diameter of Φ110mm, an outer diameter of Φ150mm, and a height of 200mm. According to a conventional method in the art, use American H&V Company 1399 type glass fiber filter paper is first wound 10 layers, and then US H&V Company 1477 type glass fiber filter paper is wound 4 layers.

testing method:

Put the oil-injected screw air compressor equipped with the above test object under the conditions of motor power of 37kW, working pressure of 0.8MPa, volumetric flow rate of 6m ³ /min, and Shell Corena S3R (46#) as lubricating oil. , work continuously, and record the working time when the lubricating oil level drops below the warning line.

Test Results:

1) Low two-sided difference filter element: 5000 hours

2) Two-sided difference filter element: 4000 hours

in conclusion:

The low two-sidedness glass fiber paper of the present invention has more uniform fiber density in the thickness direction of the paper, can significantly improve the coalescence efficiency, and improve the separation ability of the coalescing filter element.

In conclusion, the present invention provides a method for reducing double-sidedness of paper, and the paper with low double-sidedness prepared therefrom, especially glass fiber paper with low double-sidedness. Through the method of the invention, the fiber distribution in the thickness direction of the paper is more uniform. The multi-layer winding coalescing filter element made of glass fiber paper with low two-sided difference provided by the invention can avoid the fluctuation of fluid coalescing ability caused by uneven distribution of fiber density. Experiments have proved that the glass fiber paper with low two-sided difference of the present invention can significantly improve the efficiency and separation capacity of the coalescing filter element.

The above description of the specific embodiments of the present invention does not limit the present invention, and those skilled in the art can make various changes or deformations according to the present invention, as long as they do not depart from the spirit of the present invention, all should belong to the scope of the appended claims of the present invention.

Claims (18)

1. reduce the poor method in paper two sides, it is characterized in that, paper is designed to multi-layer fiber layerStructure, the kinds of fibers of every layer of slurry is identical, every layer of standby slurry, making beating independently; Slurry has entered multipleThe paper machine of independent runner, the stacked shaping of manufacturing paper with pulp simultaneously in shaping district, wherein enters the stream that is close to forming netIn the slurry I in road, diameter is less than the fines content of 1 μ m than the described fines content of other each layer of slurryHigh by 5～10%; Before manufacturing paper with pulp, also comprise the rectification of slurry, make slurry present the mobile shape of high-strength micro-turbulenceState.

2. method according to claim 1, is characterized in that, except described slurry I, otherFibrous and the weight proportion of each layer of slurry is identical.

3. want the method described in 2 according to right, it is characterized in that, the fibrous of every layer of slurry is nothingThe short chopping of alkali containing glass fibre, organic binder bond and contain the fine glass wool fiber that diameter is less than 1 μ mMicroglass fiber, in described slurry I, the content of fine glass wool fiber is than the fine glass wool of other each layer of slurryFiber content is high by 5～10%.

4. want the method described in 3 according to right, it is characterized in that, described microglass fiber also comprises directlyFootpath is more than or equal to 1 μ m but is less than the raw glass cotton fiber of 3 μ m.

5. want the method described in 3 according to right, it is characterized in that, described microglass fiber is selected from boric acidSalt microglass fiber or alkali-free glass cotton fiber.

6. method according to claim 3, is characterized in that, when standby slurry, with every layer of fiberGross dry weight amount is benchmark, and the percentage by weight of various fibers is:

The short chopping 15～25% of alkali-free glass fibre, raw glass cotton fiber 0～65%, fine glass wool fiber10～65%, organic binder bond 5～10%; Wherein, the content ratio of fine glass wool fiber in described slurry IThe fine glass wool fiber content of other each layer of slurry is high by 5～10%; The formula phase of described other each layer of slurryWith.

7. want the method described in 6 according to right, it is characterized in that, when standby slurry, always dry with every layer of fiberWeight is benchmark, and the percentage by weight of various fibers is:

The short chopping 15～25% of alkali-free glass fibre, raw glass cotton fiber 40～60%, fine glass wool fiber15～30%, organic binder bond 5～10%; In described slurry I, the content of fine glass wool fiber is more each than otherThe fine glass wool fiber content of layer slurry is high by 5～10%; The formula of described other each layer of slurry is identical.

8. the poor paper in low two sides, has multi-layer fiber layer structure, by claim 1 to 7Method described in any one prepares, and wherein, ground floor is caused near forming net behaviour by described slurry IShape.

9. the poor all-glass paper in low two sides, has multi-layer fiber layer structure, wherein ground floor byThe slurry I behaviour who enters the runner of next-door neighbour's forming net causes shape; The fibrous of every layer of slurry is alkali-free glassThe short chopping of fiber, organic binder bond and contain the mineral wool that diameter is less than the fine glass wool fiber of 1 μ mFiber; In described slurry I, the content of fine glass wool fiber contains than the fine glass wool fiber of other each layer of slurryMeasure high by 5～10%.

10. the poor all-glass paper in low two sides according to claim 9, is characterized in that, described inMicroglass fiber also comprises that diameter is more than or equal to 1 μ m but is less than the raw glass cotton fiber of 3 μ m.

The 11. poor all-glass papers in low two sides according to claim 9, is characterized in that, described inMicroglass fiber is selected from borate glass cotton fiber or alkali-free glass cotton fiber.

The 12. poor all-glass papers in low two sides according to claim 9, is characterized in that standby slurryTime, taking each layer of fiber gross dry weight amount as benchmark, the percentage by weight of various fibers is:

The short chopping 15～25% of alkali-free glass fibre, raw glass cotton fiber 0～65%, fine glass wool fiber10～65%, organic binder bond 5～10%; Wherein, the content ratio of fine glass wool fiber in described slurry IThe fine glass wool fiber content of other each layer of slurry is high by 5～10%; The formula phase of described other each layer of slurryWith.

The 13. poor all-glass papers in low two sides according to claim 12, is characterized in that, standbyWhen slurry, taking every layer of fiber gross dry weight amount as benchmark, the percentage by weight of various fibers is:

The short chopping 15～25% of alkali-free glass fibre, raw glass cotton fiber 40～60%, fine glass wool fiber15～30%, organic binder bond 5～10%; In described slurry I, the content of fine glass wool fiber is more each than otherThe fine glass wool fiber content of layer slurry is high by 5～10%; The formula of described other each layer of slurry is identical.

The 14. poor all-glass papers in low two sides according to claim 9, is characterized in that, described inGround floor accounts for 15～30% of the poor all-glass paper gross weight in described low two sides.

The 15. poor all-glass papers in low two sides according to claim 14, is characterized in that instituteState ground floor and account for 20～25% of the poor all-glass paper gross weight in described low two sides.

Prepared by the poor all-glass paper in low two sides in 16. claims 9 to 15 described in any oneApplication in filter filter core.

17. application according to claim 16, is characterized in that, described filter is coagulation typeFilter.

18. 1 kinds of coagulation type filter elements, comprise in claim 9 to 15 low described in any oneThe all-glass paper that two sides is poor.