Pressure sensing type dust-free paper and preparation method thereof

Abstract

The invention relates to the technical field of dust-free paper, in particular to pressure induction type dust-free paper which comprises an upper layer material, the upper layer material is a fiber web formed by hollow fibers and ES fibers through an air laying process, the outer diameter of the hollow fibers is 20-40 microns, the wall thickness is 1.5-4 microns, and the cavity rate is 20-35%; elastic microspheres are adhered to the outer walls of the hollow fibers or between adjacent hollow fibers, the particle size of the elastic microspheres is 40-200 [mu] m, the thickness of a shell layer is 0.8-2.0 [mu] m, the compression modulus is 0.3-1.2 MPa, and 20-60% of volume compression can occur under the action of external pressure of 5-20 kPa. The technical problems that existing dust-free paper is prone to liquid retention after being pressed, the back seepage amount is large, and absorption is uneven are solved. On the basis, the invention further provides a preparation method of the pressure induction type dust-free paper.

Description

Technical Field

[0001] This invention relates to the field of cleanroom paper technology, and in particular to a pressure-sensitive cleanroom paper and its preparation method. Background Technology

[0002] Existing cleanroom paper materials are widely used in the hygiene products industry. For example, Chinese Patent Publication No. CN119507270A discloses a high-diffusion cleanroom paper and its preparation process, which includes a top layer, a middle layer, and a bottom layer from top to bottom. The top layer has hydrophilic yarns distributed longitudinally. The middle layer has electrostatic spraying area A and electrostatic spraying area B. Salt crystals are present in electrostatic spraying area B of the middle layer, and wood pulp fibers are present in electrostatic spraying area A of the middle layer. The hydrophilic yarns are located in electrostatic spraying area A of the middle layer surface. Menstrual blood loses less capillary force in the top and middle layers and can diffuse over a large area in the bottom layer. Wood pulp fibers and sodium salt crystals are distributed alternately. Due to the good deformation resistance of ES fibers, the hollow structure of wood pulp fibers is protected from deformation under pressure. At the same time, it avoids the phenomenon of excessive wood pulp fiber absorption and agglomeration. It has multiple absorption capabilities and solves the technical problems of weak absorption capacity, poor diffusion effect, and easy local saturation blockage of existing cleanroom paper.

[0003] Current cleanroom paper materials primarily rely on static capillary action to conduct liquids. However, due to the disordered fiber arrangement and uneven pore size distribution, liquids tend to saturate and become trapped in high-pressure localized areas, leading to significant rewetting and uneven absorption. This is especially problematic in applications like sanitary napkins and diapers, where uneven body pressure significantly inhibits liquid diffusion in high-pressure zones, creating localized saturation and rewetting risks that severely impact user comfort and dryness. Traditional improvement methods primarily enhance liquid diffusion by adding hydrophilic modifications or absorbent fibers. However, under repeated pressurization cycles, the material often collapses significantly, weakening capillary force differences and making it difficult to maintain dynamic liquid conduction.

[0004] Therefore, developing a pressure-sensing and intelligently fluid-guiding paper is of great significance for improving the comfort, safety, and reliability of sanitary napkin products. Summary of the Invention

[0005] Therefore, to address the aforementioned problems, this invention proposes a pressure-sensitive cleanroom paper, which solves the technical problem that existing cleanroom papers easily retain liquid after being pressed, leading to large rewetting and uneven absorption. Based on this, a method for preparing the pressure-sensitive cleanroom paper is also proposed.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a pressure-sensitive cleanroom paper, comprising an upper layer material, wherein the upper layer material is a fiber web formed by airflow forming process comprising hollow fibers and ES fibers, wherein the outer diameter of the hollow fibers is 20μm-40μm, the wall thickness is 1.5μm-4μm, and the cavity ratio is 20%-35%;

[0007] Elastic microspheres are adhered to the outer wall of the hollow fiber or between adjacent hollow fibers. The elastic microspheres have a particle size of 40μm-200μm, a shell thickness of 0.8μm-2.0μm, and a compression modulus of 0.3MPa-1.2MPa. They can undergo 20%-60% volume compression under external pressure of 5kPa-20kPa.

[0008] Furthermore, after a light calendering process with a linear pressing of 10N / mm-25N / mm, the basis weight of the upper layer material is 30g / m². 2 -45g / m 2 The thickness is 0.5mm-0.7mm;

[0009] Furthermore, the elastic microspheres are acrylate or polyolefin core-shell hollow microspheres. The elastic microspheres achieve volume reduction through reversible compression of the elastic shell. Under external pressure, volume compression can occur, releasing the stacking constraints between local fibers and causing the gaps between adjacent fibers to be passively opened. The elastic microspheres have an elastic recovery rate, and the recovery rate exceeds 90% after decompression, thereby maintaining the cyclic reversibility of the structure.

[0010] Furthermore, the hollow fiber is polypropylene or polyethylene terephthalate.

[0011] Furthermore, it also includes a lower layer material, which is a base fabric layer formed by carding and interlacing hydrophilic fine denier fibers and hydrophilic modified ES fibers. The mass ratio of hydrophilic fine denier fibers to hydrophilic modified ES fibers is 1:(7-9), and the linear density of the hydrophilic fine denier fibers is 1D-1.8D and the length is 6mm-8mm.

[0012] The electrostatic spraying process on the base fabric layer forms liquid guiding tracks in the longitudinal and transverse directions. The liquid guiding tracks are set in the transverse and / or longitudinal directions. The hydrophilicity of the liquid guiding tracks is enhanced by the hydrophilic coating of electrostatic spraying, while the non-liquid guiding tracks maintain weak hydrophilicity. The liquid migration is guided by the hydrophilic gradient.

[0013] Multiple temporary storage units are formed by hot pressing on the lower side of the liquid guiding trajectory. Each temporary storage unit has a microcavity structure and an area of ​​1 mm². 2 -10mm 2 The temporary storage unit is filled with highly hydrophilic modified fiber bundles.

[0014] Furthermore, the lower layer material is shaped by hot air or hot rolling, with a basis weight of 20 g / m³. 2 -35g / m 2 The thickness is 0.3mm-0.45mm.

[0015] Furthermore, the highly hydrophilic modified fiber is a maleic anhydride or sulfonate grafted modified fiber or other similar functional modified fiber, and the total mass of the highly hydrophilic modified fiber bundle does not exceed 8 wt% of the basis weight of the base fabric layer.

[0016] A method for preparing pressure-sensitive cleanroom paper based on the same inventive concept includes the following steps: upper layer material preparation:

[0017] Hollow fibers and ES fibers are mixed in a predetermined ratio. After the mixed fibers are opened and combed, an air-flow web forming process is used to form a fiber web.

[0018] An elastic microsphere emulsion is applied to a pre-defined high-pressure zone of the fiber web using a zoned spraying process. The elastic microsphere emulsion has a solid content of 30%-40%, and the spraying application rate is 3 g / m². 2 -8g / m 2 ;

[0019] After spraying, perform in-situ curing treatment and dry at 90℃-120℃ for 30s-120s.

[0020] The fiber web is subjected to penetrating hot air treatment at a temperature of 140℃-150℃ for 4s-8s, which melts the low-melting-point components of the ES fiber and forms bonding points.

[0021] The warp is lightly rolled.

[0022] Furthermore, the mixing ratio of hollow fiber to ES fiber is (0.2-0.8):1. Under external pressure, the cross-section of hollow fiber changes from circular to elliptical or partially collapses, resulting in an increase in equivalent pore size and a decrease in capillary pressure.

[0023] Furthermore, it also includes the preparation steps of the underlying material:

[0024] The base fabric is made of hydrophilic fine denier fibers as the main body and hydrophilic modified ES fibers as the skeleton, which are carded and interlaced to form a base layer;

[0025] Liquid-conducting tracks are formed in the longitudinal and transverse directions of the base fabric layer through electrostatic spraying.

[0026] On the lower side of the liquid guiding trajectory, multiple temporary storage units are hot-pressed at an array spacing of 3mm-10mm. Each temporary storage unit has a microcavity structure with an opening size of 1.0mm-3.0mm and a depth of 0.1mm-0.3mm.

[0027] Highly hydrophilic modified fiber bundles are filled and shaped within the temporary storage unit;

[0028] The lower layer material is shaped by hot air or hot rolling, with the weight controlled at 20 g / m². 2 -35g / m 2 The thickness is 0.3mm-0.45mm;

[0029] The upper layer material is partially or completely bonded, pressed, or welded to the lower layer material to form a whole.

[0030] By adopting the aforementioned technical solution, the beneficial effects of the present invention are:

[0031] 1. Hollow fibers, being thin-walled hollow cylindrical structures, gradually change their cross-section from circular to elliptical or partially collapse under external pressure. This change in the fiber's outer contour reduces the bonding area between fibers, loosening their arrangement and resulting in an increased equivalent pore size. According to the Yang-Laplace equation, this increased pore size leads to a decrease in capillary pressure, weakening the liquid absorption capacity of the pressurized region and providing a driving force for liquid migration to the lower liquid guide rails. In contrast, elastic microspheres achieve volume reduction through the reversible compression of their elastic shells. Under external pressure, they can undergo volume compression, releasing the localized packing constraints between fibers and passively widening the gaps between adjacent fibers. Simultaneously, the elastic microspheres possess a certain elastic recovery rate, partially returning to their original shape after pressure relief, thus maintaining the cyclic reversibility of the structure. This design dynamically enlarges the pore size in the pressurized region, significantly reducing capillary pressure.

[0032] 2. By using light calendering, the weight and thickness of the upper layer material are controlled within a reasonable range, which ensures the structural strength and stability of the material while maintaining its good breathability and softness, thereby improving the overall performance and user experience of the product.

[0033] 3. Acrylic or polyolefin core-shell hollow microspheres are used as elastic elements. These microspheres can undergo reversible compression under external pressure, releasing the packing constraints between fibers, increasing fiber spacing, and quickly returning to their original shape after pressure relief. This maintains the material's cyclic reversibility and long-term stability, effectively extending the product's service life. Of course, other conventional materials capable of achieving the same functions can also be selected.

[0034] 4. Polypropylene or polyethylene terephthalate is selected as the hollow fiber material. These two materials have good chemical stability and mechanical properties, ensuring that the hollow fiber maintains its structural integrity during multiple pressurization-depressurization cycles, and is not easily deformed or damaged, thus guaranteeing the overall performance and reliability of the cleanroom paper. Of course, other conventional materials that can achieve the same function can also be selected.

[0035] 5. The lower layer material, through a combination of hydrophilic fine denier fibers and hydrophilic modified ES fibers, along with the design of liquid guiding tracks and temporary storage units, achieves rapid directional liquid transport and instantaneous buffering. The liquid guiding tracks ensure that liquid enters preferentially and is transported rapidly, while the temporary storage units can briefly accept a portion of the liquid during peak input, reducing the risk of backflow and improving the product's liquid absorption capacity and user comfort.

[0036] 6. By using hot air or hot rolling to shape the material, the weight and thickness of the lower layer are controlled, ensuring that it has sufficient structural strength to support the upper layer and transport liquids, while maintaining good softness and fit, thus improving the overall comfort and usability of the product.

[0037] 7. Limiting the total mass ratio of highly hydrophilic modified fiber bundles can ensure good liquid absorption performance of the underlying material while avoiding problems such as fiber bundle gel agglomeration clogging the microcavity structure or excessive cost caused by excessive fiber bundles, thus achieving a balance between performance and cost optimization.

[0038] 8. A method for preparing pressure-sensitive cleanroom paper ensures that the upper layer material has good pressure-sensing performance and structural stability by precisely controlling the preparation process of the upper layer material, including fiber mixing, airflow web formation, partitioned spraying of elastic microsphere emulsion, in-situ curing, penetrating hot air treatment and light calendering, thus providing a strong guarantee for the overall performance of the cleanroom paper.

[0039] 9. By optimizing the mixing ratio of hollow fibers and ES fibers, the pressure-bearing capacity and liquid conductivity of the upper layer material can be improved while ensuring good air permeability and softness. Under external pressure, the change in the cross-sectional area of ​​the hollow fibers helps to increase the equivalent pore size and reduce capillary pressure, thereby promoting rapid liquid conduction.

[0040] 10. The preparation method of the lower layer material ensures excellent liquid conductivity and buffering capacity by precisely controlling steps such as carding, web laying, electrostatic spraying of liquid guiding trajectory, hot pressing and temporary storage unit, and hot air or hot rolling for shaping of hydrophilic fine denier fibers and hydrophilic modified ES fibers. Combined with the upper layer material, this forms a highly efficient and stable liquid management system, significantly improving the overall performance and effectiveness of the cleanroom paper. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the structure of the upper layer material in this invention.

[0042] Figure 2 This is a schematic diagram of the structure of the lower layer material in this invention.

[0043] Figure label:

[0044] 1. Upper layer material; 11. Hollow fiber; 12. ES fiber; 13. Elastic fiber; 2. Lower layer material; 21. Base fabric layer; 22. Liquid guiding track; 23. Temporary storage unit; 24. Hydrophobic microstrip. Detailed Implementation

[0045] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0046] refer to Figure 1 , Figure 2 This embodiment provides a pressure-sensitive cleanroom paper, including an upper material 1. The upper material 1 is a fiber web formed by airflow forming process, comprising hollow fibers 11 and coarse denier weakly hydrophilic ES fibers 12. The hollow fibers 11 have an outer diameter of 20μm-40μm, a wall thickness of 1.5μm-4μm, and a cavity ratio of 20%-35%.

[0047] The outer diameter can be 20μm, 25μm, 30μm, 35μm, or 40μm, or other values ​​between 20μm and 40μm. The wall thickness can be 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, or 4μm, or other values ​​between 1.5μm and 4μm. The cavity ratio can be 20%, 25%, 30%, or 35%, or other values ​​between 20% and 35%.

[0048] Elastic microspheres are adhered to the outer wall of the hollow fiber 11 or between adjacent hollow fibers 11. The elastic microspheres have a particle size of 40μm-200μm, a shell thickness of 0.8μm-2.0μm, and a compression modulus of 0.3MPa-1.2MPa. They can undergo 20%-60% volume compression under an external pressure of 5kPa-20kPa.

[0049] The particle size can be 40μm, 80μm, 120μm, 160μm, or 200μm, or other values ​​within the range of 40μm-200μm. The shell thickness can be 0.8μm, 1μm, 1.2μm, 1.4μm, 1.6μm, 1.8μm, or 2.0μm, or other values ​​within the range of 0.8μm-2.0μm. The compressive modulus can be 0.3MPa, 0.5MPa, 0.7MPa, 0.9MPa, 1MPa, or 1.2MPa, or other values ​​within the range of 0.3MPa-1.2MPa. The external pressure can be 5kPa, 10kPa, 15kPa, or 20kPa, or other values ​​within the range of 5kPa-20kPa. The volume compression rate can be 20%, 30%, 40%, 50% or 60%, or other values ​​between 20% and 60%.

[0050] After light calendering with a linear pressing of 10N / mm-25N / mm, the weight of the upper layer material is 30g / m³ per gram. 2 -45g / m 2 The thickness is 0.5mm-0.7mm.

[0051] The linear compression can be 10 N / mm, 15 N / mm, 20 N / mm, or 25 N / mm, or other values ​​between 10 N / mm and 25 N / mm. The basis weight of the upper material can be 30 g / m³. 2 33g / m 2 36g / m 2 39g / m 2 42g / m 2 Or 45g / m 2 Of course, you can also choose 30g / m 2 -45g / m 2 Other values ​​within the range are also possible. The thickness can be 0.5mm, 0.55mm, 0.6mm, 0.65mm or 0.7mm, or other values ​​between 0.5mm and 0.7mm.

[0052] The elastic microspheres are core-shell hollow microspheres made of acrylate or polyolefin. The elastic microspheres achieve volume reduction through the reversible compression of the elastic shell. Under external pressure, volume compression can occur, releasing the stacking constraints between local fibers and causing the gaps between adjacent fibers to be passively opened. The elastic microspheres have an elastic recovery rate, and the recovery rate after decompression exceeds 90%, such as 90%, 92%, 94%, 96%, 98%, or 99%, thereby maintaining the cyclic reversibility of the structure.

[0053] The hollow fiber 11 is polypropylene or polyethylene terephthalate, or other materials with similar properties and functions.

[0054] It also includes a lower layer material 2, which is a base fabric layer 21 formed by carding and interlacing hydrophilic fine denier fibers and hydrophilic modified ES fibers 12. The mass ratio of hydrophilic fine denier fibers to hydrophilic modified ES fibers 12 is 1:(7-9), such as 1:7, 1:8, or 1:9. The linear density of the hydrophilic fine denier fibers is 1D-1.8D, and the length is 6mm-8mm.

[0055] The linear density can be 1D, 1.2D, 1.4D, 1.6D, or 1.8D, or other values ​​between 1D and 1.8D. The length can be 6mm, 6.5mm, 7mm, 7.5mm, or 8mm, or other values ​​between 6mm and 8mm.

[0056] The electrostatic spraying process on the base fabric layer 21 forms liquid guiding tracks 22 in the longitudinal and transverse directions. The liquid guiding tracks 22 are arranged in the transverse and / or longitudinal directions. The liquid guiding tracks 22 have strong hydrophilic properties, while the non-liquid guiding tracks maintain weak hydrophilic properties.

[0057] Multiple temporary storage units 23 are formed by hot pressing on the lower side of the liquid guiding trajectory 22. Each temporary storage unit 23 has a microcavity structure and an area of ​​1 mm². 2 -10mm 2 The temporary storage unit 23 is filled with highly hydrophilic modified fiber bundles.

[0058] Among them, the highly hydrophilic modified fiber is maleic anhydride or sulfonate grafted modified fiber or other similar functional modified fiber. The total mass percentage of the highly hydrophilic modified fiber bundle does not exceed 8 wt% of the base fabric layer 21 basis weight, such as 8 wt%, 7.5 wt%, 7 wt%, 6 wt%, 4 wt% or 2 wt%. The lower the total mass percentage, the worse the effect.

[0059] The area of ​​the temporary storage unit 23 can be 1 mm². 2 2mm 2 4mm 2 6mm 2 7mm 2 9mm 2 or 10mm 2 Of course, you can also choose 1mm. 2 -10mm 2 Other values ​​between.

[0060] The lower layer material 2 is shaped by hot air or hot rolling, with a basis weight of 20g / m³. 2 -35g / m 2 The thickness is 0.3mm-0.45mm.

[0061] The basis weight of the lower layer material can be 20 g / m³. 2 23g / m 2 26g / m 2 29g / m 2 32g / m 2 Or 35g / m 2 Of course, you can also choose 20g / m 2 -35g / m 2 Other values ​​within the range are also possible. The thickness can be 0.3mm, 0.35mm, 0.4mm or 0.45mm, or other values ​​between 0.3mm and 0.45mm.

[0062] A method for preparing pressure-sensitive cleanroom paper based on the same inventive concept includes the following steps: preparation of upper material 1:

[0063] Hollow fiber 11 and ES fiber 12 are mixed in a predetermined ratio. After the mixed fibers are opened and combed, an air-flow web forming process is used to form a fiber web.

[0064] An elastic microsphere emulsion is applied to a pre-defined high-pressure zone of the fiber web using a zoned spraying process. The elastic microsphere emulsion has a solid content of 30%-40%, and the spraying application rate is 3 g / m². 2 -8g / m 2 ;

[0065] To prevent particle migration and burial, in-situ curing treatment is performed after spraying, and drying is carried out at 90℃-120℃ for 30s-120s.

[0066] The fiber web is subjected to penetrating hot air treatment at a temperature of 140℃-150℃ for 4s-8s, which melts the low-melting-point components of ES fiber 12 and forms bonding points, fixing the overall structure without affecting the compressibility of hollow fiber 11 and microspheres.

[0067] The warp is lightly rolled.

[0068] The above-mentioned process parameter ranges can be arbitrarily selected within the numerical range. For example, the solid content of the elastic microsphere emulsion can be 30%, 32%, 34%, 36%, 38%, or 40%, and the coating amount can be 3g / m³. 2 4g / m 2 5g / m 2 6g / m 2 7g / m 2 or 8g / m 2 .

[0069] The mixing ratio of hollow fiber 11 to ES fiber 12 is (0.2-0.8):1, such as 0.2:1, 0.4:1, 0.6:1, or 0.8:1.

[0070] Under external pressure, the cross-section of the hollow fiber 11 changes from a circle to an ellipse or collapses locally, resulting in an increase in the equivalent pore size and a decrease in capillary pressure.

[0071] Hollow fiber 11 is a thin-walled hollow cylindrical structure. Under external pressure, the fiber cross-section gradually changes from circular to elliptical or partially collapses. This change in the fiber's outer contour reduces the bonding area between fibers, loosening their arrangement and resulting in an increased equivalent pore size. According to the Yang-Laplace equation, the increased pore size leads to a decrease in capillary pressure, weakening the liquid absorption capacity of the pressurized area and providing a driving force for the liquid to migrate to the lower liquid guide rail. In contrast, elastic microspheres achieve volume reduction through the reversible compression of their elastic shell. Under external pressure, they can undergo volume compression, releasing the localized packing constraints between fibers and passively widening the gaps between adjacent fibers. Simultaneously, the elastic microspheres possess a certain elastic recovery rate, partially returning to their original shape after pressure relief, thus maintaining the cyclic reversibility of the structure. This design dynamically enlarges the pore size in the pressurized area, significantly reducing capillary pressure.

[0072] It also includes the preparation steps of the lower layer material 2:

[0073] The base fabric layer 21 is formed by combing and interlacing hydrophilic fine denier fibers as the main body and hydrophilic modified ES fibers 12 as the skeleton.

[0074] By electrostatically spraying a hydrophilic coating, liquid-conducting tracks 22 are formed in the longitudinal and transverse directions of the base fabric layer 21. The liquid-conducting tracks have strong hydrophilicity, while the non-liquid-conducting tracks maintain weak hydrophilicity. The liquid migration is guided by the hydrophilicity gradient.

[0075] On the lower side of the liquid guiding trajectory 22, multiple temporary storage units 23 are hot-pressed at an array spacing of 3mm-10mm. These temporary storage units 23 are fabricated using a hot-pressed microcavity method, with highly hydrophilic modified fiber bundles simultaneously filled and shaped within them. The forming method involves using a mold heated to 160℃-185℃ and pressing the fiber web instantaneously for 1-5 seconds under a pressure of 0.5MPa-2.0MPa. Each temporary storage unit 23 has a microcavity structure with an opening size of 1.0mm-3.0mm and a depth of 0.1mm-0.3mm. The highly hydrophilic modified fiber bundles are then filled and shaped within the temporary storage unit 23. During the hot-pressing process, the hot-melt components in the base fabric layer 21 melt and flow to the vicinity of the microcavities, achieving self-sealing and effectively preventing the filler from migrating or falling off during use. This design allows for the brief reception of a portion of the liquid during peak input and the gradual release of the liquid to the absorbent core after pressure relief, thereby buffering instantaneous impacts and reducing the risk of backflow.

[0076] The lower layer material 2 is shaped by hot air or hot rolling, with a controlled basis weight of 20 g / m³. 2 -35g / m 2 The thickness is 0.3mm-0.45mm;

[0077] The upper material 1 and the lower material 2 are partially or completely bonded, pressed, or welded together to form a whole.

[0078] In addition, hydrophobic microstrips 24 are constructed on both sides of the liquid guiding track 22 on the base fabric layer 21. The width of the hydrophobic microstrips 24 is controlled between 0.5mm and 1.5mm, and the contact angle is increased to more than 110°, thereby forming a lateral barrier in terms of capillary force and inhibiting the diffusion of liquid out of the track.

[0079] During use, when the pore size of the high-pressure area of ​​the upper material 1 is passively enlarged and the capillary pressure decreases, the liquid will automatically flow to the liquid guide rail area with smaller pore size and higher capillary pressure under pressure, and will be quickly transferred to the absorbent core under the sanitary napkin through the lower material 2.

[0080] Although the invention has been specifically shown and described in conjunction with preferred embodiments, those skilled in the art should understand that various changes in form and detail may be made to the invention without departing from the spirit and scope of the invention as defined in the appended claims, all of which shall be within the scope of protection of the invention.

Claims

1. A pressure-sensitive cleanroom paper, characterized in that: The material includes an upper layer, which is a fiber web formed by airflow forming process of hollow fibers and ES fibers. The hollow fibers have an outer diameter of 20μm-40μm, a wall thickness of 1.5μm-4μm, and a cavity ratio of 20%-35%. Elastic microspheres are adhered to the outer wall of the hollow fiber or between adjacent hollow fibers. The elastic microspheres have a particle size of 40μm-200μm, a shell thickness of 0.8μm-2.0μm, and a compression modulus of 0.3MPa-1.2MPa. They can undergo 20%-60% volume compression under external pressure of 5kPa-20kPa.

2. The pressure-sensitive cleanroom paper according to claim 1, characterized in that: After light calendering with a linear pressing of 10N / mm-25N / mm, the basis weight of the upper layer material is 30g / m². 2 -45g / m 2 The thickness is 0.5mm-0.7mm.

3. The pressure-sensitive cleanroom paper according to claim 1, characterized in that: The elastic microspheres are core-shell hollow microspheres made of acrylate or polyolefin. The elastic microspheres achieve volume reduction through the reversible compression of the elastic shell. Under external pressure, volume compression can occur, releasing the stacking constraints between local fibers and causing the gaps between adjacent fibers to be passively opened. The elastic microspheres have an elastic recovery rate, and the recovery rate exceeds 90% after decompression, thereby maintaining the cyclic reversibility of the structure.

4. The pressure-sensitive cleanroom paper according to claim 1, characterized in that: The hollow fiber is made of polypropylene or polyethylene terephthalate.

5. The pressure-sensitive cleanroom paper according to claim 1, characterized in that: It also includes a lower layer material, which is a base fabric layer formed by carding and interlacing hydrophilic fine denier fibers and hydrophilic modified ES fibers. The mass ratio of hydrophilic fine denier fibers to hydrophilic modified ES fibers is 1:(7-9). The linear density of the hydrophilic fine denier fibers is 1D-1.8D and the length is 6mm-8mm. The base fabric layer is coated with an electrostatic spraying process to form liquid guiding tracks in the longitudinal and transverse directions. The liquid guiding tracks are set in the transverse and / or longitudinal directions. The hydrophilicity of the liquid guiding tracks is enhanced by the electrostatic spraying hydrophilic coating, while the non-liquid guiding tracks maintain weak hydrophilicity. The liquid migration is guided by the hydrophilic gradient. Multiple temporary storage units are formed by hot pressing on the lower side of the liquid guiding trajectory. Each temporary storage unit has a microcavity structure and an area of ​​1 mm². 2 -10mm 2 The temporary storage unit is filled with highly hydrophilic modified fiber bundles.

6. The pressure-sensitive cleanroom paper according to claim 5, characterized in that: The lower layer material is shaped by hot air or hot rolling, with a basis weight of 20g / m³. 2 -35g / m 2 The thickness is 0.3mm-0.45mm.

7. The pressure-sensitive cleanroom paper according to claim 5, characterized in that: The highly hydrophilic modified fiber is a maleic anhydride or sulfonate grafted modified fiber, and the total mass of the highly hydrophilic modified fiber bundle does not exceed 8 wt% of the basis weight of the base fabric layer.

8. A method for preparing pressure-sensitive cleanroom paper, using the pressure-sensitive cleanroom paper according to any one of claims 1 to 7, characterized in that, Including the upper layer material preparation steps: Hollow fibers and ES fibers are mixed in a predetermined ratio. After the mixed fibers are opened and combed, an air-flow web forming process is used to form a fiber web. An elastic microsphere emulsion is applied to a pre-defined high-pressure zone of the fiber web using a zoned spraying process. The elastic microsphere emulsion has a solid content of 30%-40%, and the spraying application rate is 3 g / m². 2 -8g / m 2 ; After spraying, perform in-situ curing treatment and dry at 90℃-120℃ for 30s-120s. The fiber web is subjected to penetrating hot air treatment at a temperature of 140℃-150℃ for 4s-8s, which melts the low-melting-point components of the ES fiber and forms bonding points.

9. The method for preparing pressure-sensitive cleanroom paper according to claim 8, characterized in that: The mixing ratio of hollow fiber to ES fiber is (0.2-0.8):

1. Under external pressure, the cross-section of hollow fiber changes from circular to elliptical or partially collapses, resulting in an increase in equivalent pore size and a decrease in capillary pressure.

10. The method for preparing pressure-sensitive cleanroom paper according to claim 8, characterized in that, It also includes the preparation steps of the underlying material: The base fabric is made of hydrophilic fine denier fibers as the main body and hydrophilic modified ES fibers as the skeleton, which are carded and interlaced to form a base layer; Liquid-conducting tracks are formed in the longitudinal and transverse directions of the base fabric layer through electrostatic spraying. On the lower side of the liquid guiding trajectory, multiple temporary storage units are hot-pressed at an array spacing of 3mm-10mm. Each temporary storage unit has a microcavity structure with an opening size of 1.0mm-3.0mm and a depth of 0.1mm-0.3mm. Highly hydrophilic modified fiber bundles are filled and shaped within the temporary storage unit; The lower layer material is shaped by hot air or hot rolling, with the weight controlled at 20 g / m². 2 -35g / m 2 The thickness is 0.3mm-0.45mm; The upper layer material is partially or completely bonded, pressed, or welded to the lower layer material to form a whole.

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