WO2023202649A1 - Spunlace non-woven fabric and filter material prepared therefrom - Google Patents

Abstract

Disclosed in the present invention are a spunlace non-woven fabric and a filter material prepared therefrom. The spunlace non-woven fabric contains 40-100% by weight of superfine polyphenylene sulfide fibers and 0-60% by weight of ordinary polyphenylene sulfide fibers, wherein the average fineness of the superfine polyphenylene sulfide fibers is 0.6-1.1 dtex. In a longitudinal cross section of the spunlace non-woven fabric, the cross section of fibers is in a flat or round shape, and within the thickness range of 50 μm from the upper surface of the non-woven fabric, the proportion of the fibers having a flat cross section to all the fibers is 25% or more. The spunlace non-woven fabric of the present invention has the characteristics of a stable structure and a small pore size, and the filter material prepared therefrom has the characteristics of high trapping efficiency, low pressure loss and longer cycle time. The filter material of the present invention can be applied to the filtering fields of garbage incinerators, coal-fired boilers or metal smelting furnaces, etc., under the condition of a high filtering wind speed of 1.5 m/min.

Description

Spunlaced nonwoven fabric and filter material made from it Technical field

The invention relates to a spunlaced non-woven fabric and a filter material prepared therefrom.

Background technique

In recent years, the "smog" problem has become increasingly serious. At present, the country and local governments have promulgated increasingly strict emission standards. In order to cope with ultra-low emission requirements, ultra-fine mixed filter bags are commonly used in filters, and ultra-fine mixed fiber filters are used. Although the produced filter bag meets the 10 mg/Nm ³ emission standard for coal-fired power plants, there is still uncertainty within 5 mg/Nm ³ , and if the filter bag made of ultra-fine mixed fiber is to reach 5 mg/Nm ³ To achieve internal emissions, in addition to increasing the proportion of ultrafine fibers, it is also necessary to increase the overall weight and ultrafine mixing uniformity to meet the requirements, and it will also increase costs. In addition, the current filter bags are made of needle-punched non-woven fabrics. Due to the large pore size of the needle-punched non-woven fabrics, the filtration effect of the resulting felt is poor, and it is difficult to meet the emission requirements of 5mg/ ^Nm3 when the filtration wind speed exceeds 1.0m/min. Require.

For example, Chinese published patent CN101406779A discloses a filter material containing polyphenylene sulfide fiber reinforced fabric. The filter surface layer is a fine fiber layer composed of fine fibers with an average diameter of 3 to 12um. The fine fiber layer is made by needle punching. Needle-punched non-woven fabrics made by the method. However, the requirements for card clothing during carding are higher, requiring finer and denser needles, and there are also requirements for the needle type of the acupuncture machine. Whether the resulting filter material can reach 5mg /Nm ³ There is huge suspense.

Another example is the Chinese published patent CN109049910A, which discloses a double-surface high-precision filter felt with a superfine fiber surface compounded with a PTFE microporous membrane. The layer structure of the filter felt from the surface to the management surface is a PTFE microporous membrane layer - an ultrafine fiber layer. - Base fabric layer - Fiber mesh layer. Although the filter felt can meet ultra-low emission requirements, due to the low air permeability of the PTFE microporous membrane itself and the ultrafine fiber layer, when the filter is used in a dust collector, the initial pressure The loss is high, and the PTFE membrane is easily damaged. After one year of use, it may be difficult to reach 5 mg/Nm ³ due to membrane damage. In addition, PTFE-coated products have too high requirements for filtration wind speed, and the membrane will quickly fail when it exceeds 0.8m/minute.

Contents of the invention

The purpose of the present invention is to provide a spunlace non-woven fabric with stable structure and small pore size.

Another object of the present invention is to provide a filter material with high collection efficiency, low pressure loss and longer circulation time.

The technical solution of the present invention is as follows: the spunlaced nonwoven fabric of the present invention contains 40 to 100% by weight of polyphenylene sulfide ultrafine fibers and 0 to 60% by weight of polyphenylene sulfide ordinary fibers. The average fineness of the ether ultrafine fiber is 0.6 to 1.1 dtex. On the longitudinal section of the spunlace non-woven fabric, the fiber cross-section shape is flat and round, and the thickness range is 50 μm downward from the upper surface of the non-woven fabric. Flat cross-section fibers account for more than 25% of all fibers.

The ratio of the major axis to the minor axis of the flat cross-section fiber is preferably 1.5 to 15 times.

The sum of the warp strength and the weft strength of the spunlace nonwoven fabric of the present invention is preferably 450 N/5cm or more per 100 g/m ² gram weight.

The ratio of the warp strength and the weft strength of the spunlace nonwoven fabric of the present invention is preferably 1:1 to 1:3.

The air permeability of the spunlaced nonwoven fabric of the present invention is preferably 12 to 38 cm ³ /cm ² /s.

The spunlace nonwoven fabric of the present invention preferably has a basis weight of 80 to 160 g/m ² .

In the filter material made from the spunlace non-woven fabric of the present invention, the first layer is a spunlace non-woven fabric, and the second layer is a heat-resistant fiber mesh layer. The proportion of the number of polyphenylene sulfide ultrafine fibers in the distance between the contact surface extending 30 μm in the direction of the heat-resistant fiber mesh layer and the bottom surface of the heat-resistant fiber mesh layer is less than 2%.

In the filter material of the present invention, the proportion of pores with a pore size distribution greater than 20 μm in the entire material is preferably less than 20%.

The beneficial effects of the present invention are: since the spunlaced non-woven fabric of the present invention is composed of ultra-fine polyphenylene sulfide fibers and the longitudinal cross-section of the non-woven fabric has a flat and circular fiber cross-section shape, the spunlaced non-woven fabric of the present invention is The spunlaced non-woven fabric has the characteristics of small pore size and good uniformity. The filter material made from this spunlaced nonwoven fabric has the characteristics of high collection efficiency, low pressure loss and longer circulation time. The filter material of the present invention can be used in filtration systems such as garbage incinerators, coal-fired boilers or metal smelting furnaces, and can still meet the emission requirement of 5mg/ ^Nm3 when the filtration wind speed exceeds 1.0m/min.

Detailed ways

The spunlaced nonwoven fabric of the present invention contains 40 to 100% by weight of polyphenylene sulfide ultrafine fibers and 0 to 60% by weight of polyphenylene sulfide ordinary fibers. The average fineness of the polyphenylene sulfide ultrafine fibers is 0.6 ~ 1.1 dtex. When the spunlace non-woven fabric contains polyphenylene sulfide ordinary fiber, the average fineness of the polyphenylene sulfide ordinary fiber is 1.3 ~ 2.5 dtex. On the longitudinal section of the spunlace non-woven fabric, the fiber cross section The shape is flat or round, and within the thickness range of 50 μm from the upper surface of the non-woven fabric, the proportion of flat cross-section fibers in all fibers is more than 25%.

The finer the polyphenylene sulfide ultrafine fiber of the present invention and the greater the content, the smaller the pore size of the resulting spunlaced non-woven fabric, and the better the filtration performance of the filter material made from it. If the polyphenylene sulfide ultrafine fiber is If the fiber content is less than 40% by weight and the content of polyphenylene sulfide ordinary fibers is higher than 60% by weight, the amount of polyphenylene sulfide ultrafine fibers is not enough to fill the large gaps between polyphenylene sulfide ordinary fibers, and the resulting From the pore size distribution of the spunlace non-woven fabric, although the average pore size is small, there are still a small or trace amount of large pores. When the spunlace non-woven fabric is made into a filter material, it will lead to large pores that are never completely filled with dust. If it penetrates into the gap, it will be difficult to meet the emission requirements within 5mg/ ^Nm3 when the filtration wind speed exceeds 1m/min.

The average fineness of the polyphenylene sulfide ultrafine fiber of the present invention is 0.6 to 1.1 dtex. If the average fineness of the polyphenylene sulfide ultrafine fiber is greater than 1.1 dtex, the gap between the ultrafine fiber and the ultrafine fiber will also be larger. Although the resulting spunlace non-woven fabric eliminates large pores, due to the thicker ultrafine fibers, some medium-sized holes are formed. When the spunlace non-woven fabric is made into a filter material, it will make it easier for finer dust to be filtered. Penetrating the filter material, it is difficult to meet the emission requirements within 5mg/ ^Nm3 when the filtration wind speed exceeds 1m/min; if the average fineness of the polyphenylene sulfide ultrafine fiber is less than 0.6dtex, the polyphenylene sulfide fiber is too fine. , it is difficult to card and cannot produce normally, or the cotton net produced has too many neps and is too large, and the filtering performance of the resulting filter material becomes poor. Taking into account the filtration performance of the final filter material, the convenience of production, reducing the occurrence of neps, etc., the average fineness of polyphenylene sulfide ultrafine fibers is preferably 0.8 to 1.0 dtex.

When spunlaced non-woven fabrics contain polyphenylene sulfide ordinary fibers, if the average fiber of polyphenylene sulfide ordinary fibers is too large, the fibers are too thick, and the pores between thick fibers are too large. Generally, the large pores are Microfibers are relied on to fill the holes, but when the coarse fibers are too thick, the large holes formed will become correspondingly larger, and the number of microfibers cannot be completely filled. Therefore, although the average pore size of the resulting spunlace non-woven fabric is small, there are still a small or trace amount of large pores. When the spunlace non-woven fabric is made into a filter material, finer dust can easily penetrate the filter material during filtration, resulting in If the filtration effect is reduced, it will be difficult to meet the emission requirements within 5mg/ ^Nm3 when the filtration wind speed exceeds 1m/min. Taking into account the filtration performance of the final filter material, cardability during production, reduction of neps, etc., the average fineness of polyphenylene sulfide ordinary fibers is more preferably 1.5 to 2.0 dtex.

The fiber length of the PPS ultrafine fiber of the present invention is preferably 30 to 61 mm. When the length of the PPS ultrafine fiber is too long, carding is difficult and a large number of neps will be produced, making it difficult to achieve mass production processing; when the length of the PPS ultrafine fiber is too short, , the interaction between the fibers that form the fiber network is too weak and cannot be stably formed. Even after forming, the strength of the spunlaced non-woven fabric is relatively low.

In the longitudinal section of the spunlaced non-woven fabric of the present invention, the fiber cross-section shapes are flat and round, and within the thickness range of 50 μm downward from the upper surface of the non-woven fabric, the proportion of flat cross-section fibers in all fibers is more than 25%.

The flat shape may be an ellipse or a rectangle, or may be a shape between an ellipse and a rectangle.

The fiber with a flat cross-section may be the fiber raw material itself having a flat cross-section, or may be post-processed to form a flat cross-section, etc.

If the fiber raw material itself has a flat cross-section, the fibers of the flat cross-section are evenly distributed in the non-woven fabric, and the upper surface at this time is any side of the non-woven fabric; if the flat cross-section is formed after post-processing , the part of the flat section close to the processing surface has more fibers distributed, and the upper surface at this time is the processing surface.

In the longitudinal section of the spunlaced nonwoven fabric of the present invention, the fiber cross-section shapes are flat and circular. The circular cross-section fibers show a three-dimensional structure trend, and the circular cross-section fibers and the circular cross-section fibers show point-to-point contact, so the fit is not tight, while the flat cross-section fibers show a two-dimensional structural trend, and the flat cross-section fibers and the flat cross-section fibers There is surface-to-surface contact between fibers, and surface-to-point contact between flat cross-section fibers and circular cross-section fibers. The presence of flat cross-section fibers can make the fibers closer together.

Within the thickness range of 50 μm downward from the upper surface of the spunlace nonwoven fabric of the present invention, the proportion of flat cross-section fibers in all fibers is more than 25%. If it is less than 25%, there will be too much fiber in the circular cross-section and insufficient fiber in the flat cross-section in this area, and the resulting spunlace non-woven fabric will be fluffy and loose. When the spunlace non-woven fabric is made into filter material , dust will easily penetrate the filter material from the fluffy part, and its filtration effect will be difficult to meet the emission requirements within 5mg/ ^Nm3 when the filtration wind speed exceeds 1.0m/min. Considering that it is necessary to maintain good filtration performance without making ventilation too low, resulting in excessive pressure loss, it is preferable that the proportion of flat cross-section fibers in this range is 30 to 80% of all fibers. If the proportion of flat cross-section fibers in all fibers is higher than 80%, the flat fibers will be slightly closer to each other, and most of the micropores will be blocked and disappear, resulting in a decrease in the air permeability of the non-woven fabric and a slightly biased pressure loss. big.

The ratio of the major axis to the minor axis of the flat cross-section fiber is preferably 1.5 to 15 times. If it is too small, the fiber cross-section shape will tend to have a circular structure. The circular cross-section fibers and the circular cross-section fibers will have point-to-point contact, so the fit will not be tight, and the resulting spunlaced non-woven fabric will appear more complex. In the fluffy state, when the spunlaced non-woven fabric is made into filter material, dust will easily penetrate the filter material from the pores in the fluffy part, and its filtration effect will be difficult to support when the filtration wind speed exceeds 1.0m/min. /Nm ³ ; if it is too large, the fit between fibers will appear in a two-dimensional plane state, and the overlap between fibers will be too close. Although the pore size of the spunlaced non-woven fabric is Small. Although the produced filter material can meet the emission requirements of high wind speeds within 5mg/ ^Nm3 , the pressure loss of the filter material is too high and the injection cycle time is too short, which will lead to increased energy consumption during actual use. In order to simultaneously achieve high filtration at high wind speed and low pressure loss, the ratio of the long axis to the short axis of the flat cross-section fiber is more preferably 3 to 8 times.

The sum of the warp strength and the weft strength of the spunlace non-woven fabric of the present invention is preferably more than 450N/5cm at a weight of ² grams per 100g/m. The strength of the non-woven fabric depends on the uniformity of carding and the density of spunlace. , when the warp strength and weft strength of the spunlace non-woven fabric are greater, it means that the structure of the spunlace non-woven fabric is stronger, and it can be used for a long time even under the harsh dust friction conditions on site; if the spunlace non-woven fabric If the sum of the warp strength and weft strength of the cloth at a weight of ² grams per 100g/m is too small, it means that the spunlace tightness is insufficient and the density is low, which will lead to excessive air permeability of the non-woven fabric and the resulting filter material. The filtration performance cannot meet the requirement of 5mg/ ^Nm3 , and the strength of the non-woven fabric is too small, which will also affect its service life and cannot meet the needs of more than 4 years of use.

The ratio of the warp strength and the weft strength of the spunlace nonwoven fabric of the present invention is preferably 1:1 to 1:3. By laying the net in a semi-cross manner, or by a combination of semi-cross and straight laying, the ratio of warp strength and weft strength can meet the optimal requirements, and the service life of the filter material can be better guaranteed. Since the force direction during blowing is mainly in the weft direction, when the ratio of the warp strength and the weft strength is too small, the weft direction of the spunlace non-woven fabric will be easily damaged after long-term use; since the warp direction also bears a certain amount of blowing force Pressure, so when the ratio of warp strength and weft strength is too large, the warp direction of the non-woven fabric is easy to break.

The air permeability of the spunlace non-woven fabric of the present invention is preferably 12 to 38cm ³ /cm ² /s. When the air permeability of the spunlace non-woven fabric is too large, it means that the fibers are relatively fluffy and dust is easier to invade. Inside the filter material, the filtration effect is reduced and the emission requirement of 5 mg/Nm ³ cannot be met; when the air permeability of the spunlaced non-woven fabric is too small, the overall pressure loss of the non-woven fabric will be high. Considering the need to balance the relationship between dust filtration effect and air permeability, the air permeability of the needle-punched nonwoven fabric of the present invention is more preferably 18 to 30 cm ³ /cm ² /s.

The spunlace nonwoven fabric of the present invention preferably has a weight of 80 to 160 g/m ² , a thickness of 0.25 to 0.50 mm, and a density of 0.32 to 0.55 g/cm ³ . The weight, thickness and density of the non-woven fabric affect the air permeability. When the weight of the non-woven fabric is close to 80g/ ^m2 , it is necessary to appropriately reduce the thickness and increase the density to improve the air permeability of the non-woven fabric; when the non-woven fabric ^When the weight is close to 160g/m2, its thickness can be increased and its density reduced to ensure the breathability of the non-woven fabric. Considering the need to balance the relationship between dust filtration effect, air permeability, and cost to improve air permeability, the weight of the spunlaced nonwoven fabric of the present invention is more preferably 100 to 130 g/m ² , and the thickness is more preferably 0.30 to 0.42 mm, and the density is more preferably 0.34 to 0.45 g/cm ³ .

In the filter material made from the spunlace non-woven fabric of the present invention, the first layer is a spunlace non-woven fabric, and the second layer is a heat-resistant fiber mesh layer. The proportion of the number of polyphenylene sulfide ultrafine fibers in the distance between the contact surface extending 30 μm in the direction of the heat-resistant fiber mesh layer and the bottom surface of the heat-resistant fiber mesh layer is less than 2%.

In order to make the first spunlace non-woven fabric layer and the second heat-resistant fiber web layer fully adhere to each other and prevent them from being separated by being blown, the heat-resistant surface is formed from the contact surface between the spunlace non-woven fabric layer and the heat-resistant fiber web layer. There will be a certain amount of the first layer of polyphenylene sulfide ultrafine fibers in the distance between the fiber web layer and the bottom surface of the heat-resistant fiber web layer extending 30 μm in the direction, thereby ensuring that the first spunlace non-woven fabric layer is in contact with the third layer of polyphenylene sulfide. The two heat-resistant fiber web layers are fully complexed, but the contact surface of the spunlace non-woven layer and the heat-resistant fiber web layer extends 30 μm in the direction of the heat-resistant fiber web layer, and the distance between it and the bottom surface of the heat-resistant fiber web layer, The proportion of polyphenylene sulfide ultrafine fibers will not be very large. If it is too large, it means that there are a large number of polyphenylene sulfide ultrafine fibers in this area, which further explains that in the second heat-resistant fiber mesh layer The fibers will also be brought into the first spunlace non-woven fabric layer, and when the relatively thick fibers in the second heat-resistant fiber web layer are brought into the first spunlace non-woven fabric layer, the thick fibers will be It will destroy the dense microporous structure of the first spunlace non-woven fabric layer, resulting in low filtration efficiency and high air permeability of the made filter material. Considering the need to balance the filtering effect and the strong bonding between the two layers. The number of polyphenylene sulfide ultrafine fibers extending 30 μm from the contact surface of the spunlace non-woven fabric layer and the heat-resistant fiber web layer in the direction of the heat-resistant fiber web layer to the bottom surface of the heat-resistant fiber web layer The proportion is preferably 1% or less, more preferably 0.5% or less.

The form of the above-mentioned second heat-resistant fiber web layer can be a needle-punched non-woven fabric, a spun-entangled non-woven fabric, or a spun-bonded non-woven fabric. Since the needle-punched non-woven fabric has sufficient hairiness, when the first spun-entangled non-woven fabric When the first layer and the second heat-resistant fiber web layer are bonded by flame, it is easier to bond, so the form of the second heat-resistant fiber web layer is preferably needle-punched non-woven fabric. The heat-resistant fiber material can be a thermoplastic fiber with a melting point exceeding 250 degrees, such as PPS, PET, nylon, etc., because PPS fiber has better heat resistance than other thermoplastic fibers above 250 degrees and is easy to be melted by flames. Therefore, thermoplasticity The fiber is preferably PPS fiber.

In the filter material of the present invention, the proportion of pores with a pore size distribution greater than 20 μm in the entire material is preferably less than 20%. If the proportion is too large, it means that there are too many large pores in the entire filter material, resulting in dust easily penetrating the filter material. It cannot meet the emission requirements of high wind speed within 5mg/ ^Nm3 . Taking into account the filtration efficiency and air permeability of the filter material, the pores with a pore size distribution greater than 20 μm in the filter material preferably account for less than 15% of the entire material, and the pores with a pore size distribution greater than 30 μm in the filter material preferably account for 5% of the entire material. Hereinafter, the proportion of pores in the filter material with a pore size distribution greater than 40 μm preferably accounts for less than 0.5% of the entire material. That is, the fewer large pores the filter material has, the better the filtration effect. In order to obtain a filter material with high air permeability and low pressure loss, the average pore size is preferably 5 to 10 μm.

The manufacturing method of filter material of the present invention includes the following steps:

(1) Preparation of PPS spunlace non-woven fabric: Mix and feed fiber raw materials - open and blend cotton - carding - laying web - spunlace - drying - winding into cloth, and perform post-processing such as shaping and calendering as needed to prepare Spunlaced non-woven fabric is used as the first layer of filter material;

(2) Preparation of the heat-resistant fiber web layer: Use heat-resistant fibers with a diameter of 7 to 30 μm, and go through opening-carding-laying. The heat-resistant fiber web layers obtained are used as the second heat-resistant fiber web layer and The fourth heat-resistant fiber mesh layer;

(3) Preparation of fabric reinforcement layer: Use 100wt% heat-resistant fiber to weave a woven fabric with a weight of 80-200g/ ^m2 as the fabric reinforcement layer as the third layer;

(4) Preparation of filter material: Stack the prepared spunlace non-woven fabric layer, the upper layer of the heat-resistant fiber mesh, the fabric reinforcement layer, and the lower layer of the heat-resistant fiber mesh in sequence, and integrate them by needle punching and/or spunlace. , and finally obtain the filter material. Or first, the upper layer of the heat-resistant fiber mesh, the fabric reinforcement layer and the lower layer of the heat-resistant fiber mesh are laminated in sequence, integrated by needle punching and/or hydroentangling to form a support layer, and then the flame hot melt lamination method is used. Or the hot pressing method or the needle punching or spunlace method, the spunlace non-woven fabric layer is bonded to the surface of the upper layer of the heat-resistant fiber mesh, and finally the filter material is produced.

In order to maintain the compactness and integrity of the first layer structure, the present invention prefers the flame hot melt laminating method. First, use a flame to melt the fibers on the upper surface of the heat-resistant fiber mesh, and then quickly combine the spunlace non-woven fabric layer with the heat-resistant fiber mesh. The molten surface of the upper layer of the fiber mesh is bonded and pressure is applied. This method can not only maintain a high air permeability of the filter material, but also make the upper and lower layers firmly fit together. The higher air permeability can make the filter material more durable. The initial pressure loss is reduced, thereby reducing the overall pressure of the filter bag and further increasing the service life of the filter material. The increased bonding fastness between the two layers can prevent the filter material from being separated and damaged by the upper and lower layers in a long-term spray environment. In addition, compared with acupuncture and spunlace lamination, the flame hot melt lamination method will not cause damage to the spunlace non-woven fabric layer on the surface, nor will it be penetrated. During actual use, it will not cause any damage due to dust. Penetrate pinholes or water holes, causing the filtering performance of the filter material to decrease and the pressure loss to increase. Compared with the hot-pressing laminating method, the flame hot-melt laminating method has higher bonding strength, and the upper and lower layers are not easy to peel off after blowing.

The diameter of the heat-resistant fibers constituting the upper layer of the heat-resistant fiber web and the lower layer of the heat-resistant fiber web in step (2) is preferably 7.0 to 30.0 μm. When the diameter of the heat-resistant fiber is too small, the porosity of the fiber network is low, and the air permeability of the resulting filter material is low. During actual operation, the pressure loss of the filter material rises quickly; when the diameter of the heat-resistant fiber is too large, the air permeability of the resulting filter material is low. The porosity of the fiber mesh is large, the air permeability of the resulting filter material is large, and the dust particle collection efficiency is low. Considering the pressure loss, cost and processability of the filter material, the diameter of the heat-resistant fibers constituting the upper layer of the heat-resistant fiber mesh and the lower layer of the heat-resistant fiber mesh is more preferably 12.0 to 16.0 μm.

The heat-resistant fibers that constitute the heat-resistant fiber web layer are preferably thermoplastic fibers. The thermoplastic fibers can be one or more of polyphenylene sulfide, polyester, nylon, PTFE, aramid, and PI fibers, or can be PTFE, aramid, or PI fibers. One or more mixed fibers of polyester, PI fiber and PPS fiber. Considering the overall high temperature resistance of the filter material and the fact that the first layer of the filter material is a spunlace non-woven layer, the thermoplastic fiber is preferably PPS fiber.

In step (3), the heat-resistant fiber can be one or more of PPS, PTFE, aramid, and polyester, and is not limited to the above fibers.

In order to improve the overall corrosion resistance of the filter material, a PTFE film can be added to the first PPS spunlace non-woven fabric layer. The PTFE film is obtained by PTFE impregnation or PTFE coating.

The present invention will be described in more detail below through examples. The measurement methods of each physical property in the present invention are as follows.

【Fiber content】

Use a scanning electron microscope (SEM) to test the cross section of the sample. Randomly select 10 points for sample preparation and testing. The test magnification for each point is 600 times. Mark the fiber diameters in all samples in the photo. The diameters range from 7.5 μm to 10.5 μm. Those within the μm range are judged to be ultrafine fibers, and those with a diameter greater than 10.5μm are judged to be ordinary fibers. Count the number of ultrafine fibers and ordinary fibers respectively, and then calculate the ratio of their weights. The relationship between its radius and weight is: superfine fiber weight: ordinary fiber weight = number of ultrafine fibers × π × average radius of ultrafine fibers ² : number of ordinary fibers × π × average radius of ordinary fibers ² , where the average radius of the fiber The average radius of the fibers is obtained by adding the diameters of all the fibers tested and dividing them by 2, and then dividing them by the number of fibers tested.

[Proportion of flat cross-section fibers]

Use a scanning electron microscope (SEM) to test the cross-section of the sample with a thickness of more than 50 μm on the surface of the spunlace non-woven fabric. Randomly select 10 points for testing. The test magnification for each point is 600 times. View all fibers in the photo. Count the number of flat cross-section fibers and the number of ordinary circular cross-section fibers, and then calculate the ratio. The calculation formula for the proportion of flat cross-section fibers is as follows: the number of all flat cross-section fibers ÷ (the number of all ordinary circular cross-section fibers + the number of all flat cross-section fibers). In the same way, a total of 5 samples were made, tested separately, and the average value was taken.

[The ratio of the major axis to the minor axis of flat cross-section fibers]

Use a scanning electron microscope (SEM) to test the cross section of the sample. Randomly select 10 points for sample preparation and testing. The test magnification for each point is 600 times. Check all the fibers in the photo, mark all the flat cross-section fibers, and then measure The distance between the major axis and the distance between the minor axis of the flat cross-section fiber is calculated, and then the ratio of the major axis to the minor axis of the flat cross-section fiber is calculated. In the same way, a total of 5 samples were made, tested separately, and the average value was taken.

[Circular fiber diameter, average fiber fineness]

Use a scanning electron microscope (SEM) to test the surface of the sample. Randomly select 20 points for sample preparation and testing. The test magnification for each point is 600 times. The diameter of the structural fiber in the sample is randomly marked. Each point is marked with at least 10 The diameter of the root fiber. A total of at least 200 microscopic diameters should be marked, and the average value should be taken. The fiber fineness can be calculated from the fiber diameter, and the fiber fineness D=πd ² /4×L×ρ×10 ^-6 (L is 10000m, ρ is density, g/cm ³ ).

[Average fineness of flat fibers]

Use a scanning electron microscope (SEM) to test the surface of the sample. Randomly select 20 points for sample preparation and testing. The test magnification for each point is 600 times. The length L1 and width L2 of the flat structural fibers in the sample are randomly marked. Each point is The points mark the length and width of at least 10 flat fibers. A total of at least 200 microscopic lengths and widths are marked, and the average length is L _length and the average _{width is} L width. Fiber fineness can be calculated from the fiber cross-sectional area. Fiber fineness D=L _length ×L _width ×L×ρ×10 ^-6 (L is 10000m, ρ is density, g/cm ³ ).

[The sum of meridional strong force and latitudinal strong force]

Based on the provisions of the JISL1096 standard, samples were taken from the warp and weft directions respectively, and 5 samples were randomly selected from each. The sample size was 20cm × 5cm, the tensile speed was 100m/min, and the chuck spacing was 10cm. The warp strength and the weft strength of the sample are measured, and the sum of the warp strength and the weft strength is their sum. In the same way, a total of 5 samples were made, tested separately, and the average value was taken.

[The ratio of meridional strength to latitudinal strength]

Based on the provisions of the JISL1096 standard, samples were taken from the warp and weft directions respectively, and 5 samples were randomly selected from each. The sample size was 20cm × 5cm, the tensile speed was 100m/min, and the chuck spacing was 10cm. The warp strength and weft strength of the sample are measured, and the warp strength is compared with the weft strength to obtain their ratio. In the same way, a total of 5 samples were made, tested separately, and the average value was taken.

【Gram weight】

Cut the spunlace non-woven fabric into squares of 20cm×20cm. Calculate the unit area weight of the spunlace non-woven fabric from the weight. Measure 5 times and take the average of the 5 times for the final result.

【Breathability】

The air permeability of spunlace nonwoven fabrics was measured according to the Fraser type fabric air permeability test method stipulated in JISL 1096. The measurement locations were randomly selected at 10 points for measurement. In the same way, a total of 5 samples were made, tested separately, and the average value was taken.

[Proportion of the number of polyphenylene sulfide microfibers]

Use a scanning electron microscope (SEM) to test the cross section of the sample, and randomly select 10 points for sample preparation and testing. The test points must be located from the contact surface of the spunlace non-woven layer and the heat-resistant fiber mesh layer to the heat-resistant surface. The distance between the fiber mesh layer extending 30 μm and the bottom surface of the heat-resistant fiber mesh layer is 600 times. Check all the fibers in the photo and mark out all the polyphenylene sulfide ultrafine fibers, poly The calculation formula for the ratio of the number of polyphenylene sulfide ultrafine fibers is as follows: the number of polyphenylene sulfide ultrafine fibers/the number of all fibers × 100%. In the same way, a total of 5 samples were made, tested separately, and the average value was taken.

[The proportion of pores with a pore size distribution greater than 20 μm in the overall material]

Cut the material to be tested into a circle with a diameter of 1.5cm. After soaking in the surfactant for 30 minutes, place the material with the filter side upward into the test slot of the capillary flow porosity tester. Tighten the lid of the slot and conduct the test. , the test results are directly converted to the distribution of the proportion (%) of each pore size (μm) of the filter material in the entire material (including average pore size, maximum pore size μm, minimum pore size μm, and pore size distribution). Measure 3 times, and the final result is The average of three times was used to measure the proportion of pores with a pore size distribution greater than 20 μm in the overall filter material.

The pore diameter of the material is calculated as follows:

Among them, d: fiber diameter (denier),

ρw: Density of filter material (g/cm ³ ),

ρp: density of fiber (g/cm ³ ).

[VDI3926 collection efficiency, outlet dust concentration, pressure loss, cycle time]

The performance of filter materials is measured based on the standard of VDI3926. The size of the experimental sample is a circle with a diameter of 150mm. The fed dust concentration is 5.0±0.5g/m ³ , which corresponds to the VDI filtration speed of 1.0m/min at the actual use site. The wind speed is 2m/min (air volume 1.85m ³ /h), which corresponds to the VDI filtration of 1.2m/min at the actual use site. The wind speed is 2.4m/min. The order of the experiment is 30 initial rounds + 5000 stabilization rounds + the last 30 rounds. The method for the initial 30 times and the last 30 times is as follows: as the running time prolongs, the pressure difference on both sides of the filter material will gradually increase. When the pressure difference reaches 1000Pa, pulse air will clean the dust on the surface of the filter material, and then proceed. In the next process, this process is repeated 30 times. During the experiment, the changes in experimental time (t/s) and pressure are recorded, and the weight M (g) of dust that penetrates the filter material is weighed. The stabilization process refers to cleaning the filter material at intervals of 5 seconds during operation, with a cleaning pressure of 5 bar and a cleaning frequency of 5,000 times.

The outlet dust concentration C = the weight of dust passing through the filter material M/(1.85×time t/3600). The unit of the outlet dust concentration C is mg/Nm ³ . When the VDI outlet concentration is less than 0.12mg/ ^Nm3 , on-site use can meet the emission requirement of 5mg/ ^Nm3 .

Collection efficiency = (1 - outlet dust concentration C/5) × 100%.

The pressure loss is the pressure loss automatically recorded by the equipment after the last injection of the last 30 rounds.

The cycle time is the total time spent in the last 30 cycles.

[Durability (blow resistance)]

The evaluation method of durability (injection resistance) is as follows: ◎ means no damage after 40,000 injections, ○ means no damage after 30,000 injections, △ means no damage after 10,000 injections, × It means it will be damaged if it cannot be returned after 10,000 sprays.

Example 1

(1) Preparation of PPS spunlace non-woven fabric (PPS-SP): Feed 100% by weight of PPS ultrafine fiber raw material with an average fineness of 0.9dtex - opening - carding - laying - spunlace - drying - rolling Wind it into a cloth, and then process it through shaping and calendering to obtain a non-woven fabric with a weight of 120g/ ^m2 as the first layer. On the longitudinal section of the spunlaced non-woven fabric, the fiber cross-section shape is flat and round. Shape, and within the thickness range of 50 μm from the upper surface of the non-woven fabric, the proportion of flat cross-section fibers in all fibers is 65%;

(2) Preparation of heat-resistant fiber web layer: PPS fiber with a diameter of 14.5 μm is used, and after opening, carding and laying, the PPS fiber web layer is used as the second PPS fiber web layer and the fourth PPS fiber respectively. network layer;

(3) Preparation of fabric reinforcement layer: Polyphenylene sulfide short fibers with a fineness of 2.2dtex and an average diameter of 14.5μm are used for weaving, and a polyphenylene sulfide plain fabric with a weight of 107g/ ^m2 is produced as the third fabric. enhancement layer;

(4) Preparation of filter material: First, the upper layer of the heat-resistant fiber mesh, the fabric reinforcement layer and the lower layer of the heat-resistant fiber mesh are laminated in sequence, and integrated by needle punching to obtain a support layer with a weight of 460g/ ^m2 . , and then melt the PPS fibers on the support layer through flame hot melt lamination, and then laminate the first PPS spunlaced non-woven fabric layer to the surface of the support layer to finally obtain the filter of the present invention. Material. The polyphenylene sulfide extends 30 μm from the contact surface of the first PPS spunlace non-woven fabric layer and the second PPS fiber web layer in the direction of the second PPS fiber web layer to the bottom surface of the second PPS fiber web layer. The number of ultrafine fibers accounts for 0%, and the pores with a pore size distribution greater than 20 μm in the filter material account for 6% of the entire material. The physical properties of the filter material of the present invention are shown in Table 1.

Examples 2 to 15

The preparation process is the same as in Example 1, and the specific formula and physical properties are as shown in Table 1 and Table 2.

Example 16

Preparation of PPS spunlace nonwoven fabric (PPS-SP): uniformly mix 65% by weight of flat cross-section PPS fibers with an average fineness of 0.9dtex and 35% by weight of circular cross-section PPS fibers with an average fineness of 0.9dtex - feed -Opening-carding-laying-spunlace-drying-winding into cloth, and then through shaping processing, a non-woven fabric with a weight of 120g/ ^m2 is produced as the first layer. The spunlace non-woven fabric is measured In the longitudinal section, the fiber cross-section shapes are flat and round, and within the thickness range of 50 μm downward from the upper surface of the non-woven fabric, the proportion of flat cross-section fibers in all fibers is 30%. The rest of the preparation process is the same as in Example 1, and the specific formula and physical properties are shown in Table 2.

Comparative example 1

(1) Preparation of PPS spunlace non-woven fabric: Feed 100% by weight of PPS ultrafine fiber raw material with an average fineness of 1.2 dtex - opening - carding - laying net - spunlace - drying - winding into cloth, and then After shaping and calendering, a non-woven fabric with a weight of ^120m2 was produced as the first layer. On the longitudinal section of the spunlaced non-woven fabric, the fiber cross-section shape was flat and round, and from the non-woven fabric Within the thickness range of 50 μm from the upper surface, the proportion of flat cross-section fibers in all fibers is 65%;

(2) The preparation of the heat-resistant fiber mesh layer and fabric reinforcement layer is the same as in Example 1;

(3) Preparation of filter material: First, the upper layer of the heat-resistant fiber mesh, the fabric reinforcement layer and the lower layer of the heat-resistant fiber mesh are laminated in sequence, and integrated by needle punching to obtain a support layer with a weight of 460g/ ^m2 . , and then laminate the first PPS spunlace non-woven fabric layer to the surface of the support layer through a needle punching method, and finally obtain a filter material. The polyphenylene sulfide extends 30 μm from the contact surface of the first PPS spunlace non-woven fabric layer and the second PPS fiber web layer in the direction of the second PPS fiber web layer to the bottom surface of the second PPS fiber web layer. The number of ultrafine fibers accounts for 4%, and the pores with a pore size distribution greater than 20 μm in the filter material account for 18% of the entire material. The physical properties of this filter material are shown in Table 3.

Comparative example 2

(1) Preparation of PPS spunlaced non-woven fabric: 20% by weight of PPS ultrafine fibers with an average fineness of 0.9 dtex and 80% by weight of PPS ordinary fibers with an average fineness of 1.5 dtex are mixed, fed - opened - carded - Laying the net - spunlace - drying - winding into cloth, and then processed by shaping and calendering to obtain a non-woven fabric with a weight of 120g/ ^m2 as the first layer. Measure the longitudinal section of the spunlace non-woven fabric On the top, the fiber cross-section shapes are flat and round, and within the thickness range of 50 μm from the upper surface of the non-woven fabric, the proportion of flat cross-section fibers in all fibers is 65%;

(2) The preparation of the heat-resistant fiber mesh layer and fabric reinforcement layer is the same as in Example 1;

(3) Preparation of filter material: In the filter material, pores with a pore size distribution greater than 20 μm account for 21% of the entire material. The rest are the same as in Example 1. See Table 3 for specific parameters and physical properties.

Comparative example 3

(1) Preparation of PPS spunlace non-woven fabric: Feed 100% by weight of PPS ultrafine fiber raw material with an average fineness of 0.9 dtex - opening - carding - laying net - spunlace - drying - winding into cloth, and then After shaping and post-processing, a non-woven fabric with a weight of 120g/ ^m2 was produced as the first layer. It was measured that the fibers in the spunlaced non-woven fabric had a circular cross-section;

(2) The preparation of the heat-resistant fiber mesh layer and fabric reinforcement layer is the same as in Example 1;

(3) Preparation of filter material: In the filter material, pores with a pore size distribution greater than 20 μm account for 24% of the entire material. The rest are the same as in Example 1. See Table 3 for specific parameters and physical properties.

Comparative example 4

50% by weight of polyphenylene sulfide fibers with an average diameter of 14.5 μm and 50% by weight of polyphenylene sulfide fibers with an average diameter of 10 μm are used for blending, opening, carding, and laying. The needle punching density is 50 fibers/ ^cm2 are needled to form a polyphenylene sulfide fiber mesh with a weight of 220g/ ^m2 as a filter layer;

Polyphenylene sulfide short fibers with a fineness of 2.2dtex and an average diameter of 14.5μm are used for weaving to obtain a polyphenylene sulfide with a warp density of 79 fibers/5cm, a weft density of 30 fibers/5cm, and a weight of 120g/ ^m2. Phenyl sulfide plain weave fabric middle fabric reinforcement layer;

100% by weight of polyphenylene sulfide fibers with an average diameter of 14.5 μm are used for opening, carding, and netting, and then needled with a needle punching density of 50 fibers/cm ² to form a poly(phenylene sulfide) fiber with a weight of 220 g/m ² Phenyl sulfide fiber mesh serves as a non-filter layer;

Then, the filter layer, the intermediate fabric reinforcement layer, and the non-filter layer are stacked in sequence, and then needle-punched and compounded to obtain the filter material. The physical properties of the filter material are shown in Table 3.

Comparative example 5

(1) Preparation of PPS spunlace non-woven fabric: Feed 100% by weight of PPS ultrafine fiber raw material with an average fineness of 0.9 dtex - opening - carding - laying net - spunlace - drying - winding into cloth, and then After shaping and calendering, a non-woven fabric with a weight of 120g/ ^m2 was produced as the first layer. On the longitudinal section of the spunlaced non-woven fabric, the fiber cross-section shape was flat and round, and the fiber cross-section was flat and round. Within the thickness range of 50 μm from the upper surface of the woven fabric, the proportion of flat cross-section fibers in all fibers is 24%;

(2) The preparation of the heat-resistant fiber mesh layer, fabric reinforcement layer and filter material is the same as in Example 1. See Table 3 for specific parameters and physical properties.

Table 1

Table 2

table 3

According to the above table, (1) it can be seen from Example 1 and Example 2 that under the same conditions, the content of polyphenylene sulfide ultrafine fibers in the first layer of PPS spunlace non-woven fabric in the former is higher than that in the latter. The filter obtained by the former The material has a long cycle time and low dust concentration at the outlet.

(2) It can be seen from Example 1, Example 3 and Example 4 that under the same conditions, the fineness of the polyphenylene sulfide ultrafine fibers in the first layer of PPS spunlace non-woven fabric in Example 1 is within the preferred range, and the obtained The filter material has longer circulation time and lower outlet dust concentration.

(3) It can be seen from Example 2 and Example 5 that under the same conditions, in the former, the proportion of flat cross-section fibers to all fibers within the thickness range of 50 μm from the upper surface of the non-woven fabric is within the preferred range, which is consistent with the latter. In comparison, the filter material obtained by the former has a long cycle time and low pressure loss.

(4) It can be seen from Example 5 and Example 8 that under the same conditions, the average fineness of the polyphenylene sulfide ordinary fiber in the former is within a more preferred range. Compared with the latter, the filter material obtained by the former has a long circulation time and export dust. Concentration is low.

(5) It can be seen from Example 1, Example 6 and Example 7 that under the same conditions, the weight of the spunlace non-woven fabric in Example 1 is within the preferred range, and the circulation time of the obtained filter material is longer.

(6) It can be seen from Example 1, Example 9 and Example 10 that under the same conditions, the method of laminating the spunlace non-woven fabric and the support layer in Example 1 is the flame hot melt method, and the outlet dust concentration of the resulting filter material is Smaller, longer cycle times, lower pressure losses.

(7) It can be seen from Example 1, Example 11 and Example 15 that under the same conditions, the ratio of the long axis to the short axis of the flat cross-section fiber in Example 11 is not within the preferred range, and the circulation time of the obtained filter material is slightly shorter. , the pressure loss is slightly larger.

(8) It can be seen from Example 1 and Example 14 that under the same conditions, the ratio of the warp strength and the weft strength of the non-woven fabric in Example 14 is not within the preferred range. Compared with the former, the filter material obtained by the latter has Durability slightly reduced.

(10) It can be seen from Example 2 and Example 16 that under the same conditions, the flat-shaped cross-section fibers in Example 2 are post-processed to form a flat-shaped cross-section, while the flat-shaped cross-section fibers in Example 16 are the fiber raw materials themselves. Compared with the latter, the circulation time of the filter material obtained by the former is slightly longer and the pressure loss is slightly smaller.

(11) It can be seen from Example 10 and Comparative Example 1 that under the same conditions, the fiber of the polyphenylene sulfide ultrafine fiber in Comparative Example 1 is too thick, and the pores between the fibers become larger, resulting in the outlet dust concentration of the filter material. Large, and because the number of fibers per unit area decreases, the bonding strength decreases, resulting in slightly poorer durability of the filter material.

(12) It can be seen from Example 1 and Comparative Example 2 that under the same conditions, the content of polyphenylene sulfide ultrafine fibers in the first layer of PPS spunlace non-woven fabric in Comparative Example 2 is too low, and the cycle time of the resulting filter material is short. , the outlet dust concentration is high.

(13) It can be seen from Example 1 and Comparative Example 3 that under the same conditions, when all the fibers in the first layer of spunlaced non-woven fabric in Comparative Example 3 have a circular cross-section, the resulting filter material has a short circulation time and no dust. The outlet concentration is high.

(14) It can be seen from Example 1 and Comparative Example 4 that under the same conditions, when no spunlaced non-woven fabric is used in Comparative Example 4, the outlet concentration of the filter material obtained is large, and the outlet concentration is extremely large at high wind speeds.

(15) From Example 1 and Comparative Example 5, it can be seen that under the same conditions, in Comparative Example 5, within the thickness range of 50 μm from the upper surface of the non-woven fabric, the proportion of flat cross-section fibers to all fibers is too low, and the resulting filter material The cycle time is short, the dust outlet concentration is high, and the pressure loss is high.

Claims (8)

1. A kind of spunlace non-woven fabric, characterized in that: the spunlace non-woven fabric contains 40 to 100 wt% of polyphenylene sulfide ultrafine fibers and 0 to 60 wt% of polyphenylene sulfide ordinary fibers, said The average fineness of polyphenylene sulfide ultrafine fibers is 0.6 to 1.1 dtex. On the longitudinal section of the spunlaced non-woven fabric, the fiber cross-section shape is flat and round, and the thickness is 50 μm downward from the upper surface of the non-woven fabric. Within the range, the proportion of flat cross-section fibers in all fibers is more than 25%.
2. The spunlace nonwoven fabric according to claim 1, characterized in that the ratio of the long axis to the short axis of the flat cross-section fibers is 1.5 to 15 times.
3. The spunlaced non-woven fabric according to claim 1, characterized in that: the sum of the warp strength and the weft strength of the non-woven fabric per 100g/ ^m2 grams is 450N/5cm or more.
4. The spunlace nonwoven fabric according to claim 3, characterized in that the ratio of the warp strength and the weft strength of the nonwoven fabric is 1:1 to 1:3.
5. The spunlaced nonwoven fabric according to claim 1, wherein the air permeability of the nonwoven fabric is 12 to 38cm ³ /cm ² /s.
6. The spunlaced non-woven fabric according to claim 1, characterized in that the weight of the non-woven fabric is 80-160 g/m ² .
7. A filter material made from the spunlace non-woven fabric according to claim 1, characterized in that: the first layer of the filter material is a spunlace non-woven fabric layer, and the second layer is a heat-resistant fiber mesh layer, The distance from the contact surface of the spunlace non-woven fabric layer and the heat-resistant fiber web layer to the heat-resistant fiber web layer extending 30 μm in the direction of the heat-resistant fiber web layer and the bottom surface of the heat-resistant fiber web layer, the polyphenylene sulfide ultrafine fiber The proportion of roots is less than 2%.
8. The filter material according to claim 7, characterized in that: in the filter material, the proportion of pores with a pore size distribution greater than 20 μm in the entire material is less than 20%.