A kind of expansion water-blocking non-woven fabric for cable and its preparation method and application

Abstract

The invention discloses a kind of expansion water-blocking non-woven fabric for cable and its preparation method and application, and the preparation method comprises the following steps: S1, dissolving microcrystalline cellulose in alkaline solution, then adding pore-forming agent, freeze-drying to obtain cellulose sponge, and then compressing and shaping; S2, adopting spandex staple fiber and polyester staple fiber to blend, combing it and adopting needle punching to obtain spandex-polyester non-woven fabric; S3, coating water-absorbing resin powder on the surface of the prepared spandex-polyester non-woven fabric, and then fixing the compressed and shaped cellulose sponge on the side of the spandex-polyester non-woven fabric coated with water-absorbing resin powder by needle punching to form a cellulose sponge layer; S4, covering the cellulose sponge layer with a cover non-woven fabric coated with adhesive, and obtaining a water-absorbing expansion non-woven fabric by hot pressing. The present invention uses water-absorbing resin powder and cellulose sponge as water-absorbing materials, has both water absorption and water-blocking functions, can absorb water, and can block the entry of subsequent water by expansion.

Description

Technical Field

[0001] The present invention relates to a water-blocking material, in particular to an expandable water-blocking non-woven fabric for cables, and a preparation method and application thereof. Background Art

[0002] With the development of the times, cables for power supply are increasingly used in various humid environments. In these environments, the erosion of water can cause the cable outer covering to age and crack. Therefore, the development of cable outer covering non-woven fabrics with water absorption and water blocking functions is imperative. At present, water-blocking powder (sodium polyacrylate, polyvinyl alcohol, carboxymethyl cellulose, etc.) with super absorbent resin as the main component is often coated on fibers such as polyester and glass fiber to make water-blocking yarn. When water vapor invades, it can quickly absorb water and expand to form a gel, blocking all possible water seepage channels, thereby providing completely reliable sealing and waterproof performance. For example, patent CN111172760A discloses a high-expansion water-blocking yarn and its production process. The water-blocking yarn includes fibers, an adhesive layer formed on the surface of the fibers, and a super absorbent resin layer on the surface of the adhesive layer. The super absorbent resin layer is formed by drying a mixed solution of a post-crosslinked absorbent resin solution, polyethylene glycol, and deionized water on the adhesive layer.

[0003] The strength of the coating material on the fiber surface increases with the increase in adhesive content, while the water absorption and expansion properties of the coating material are affected by the content of highly absorbent resin. When the adhesive content is high, the coating material has higher strength, but the dense surface formed wraps around the highly absorbent resin, which easily inhibits the expansion properties of the coating, resulting in a decrease in the initial water absorption rate, causing unqualified indicators and failure to achieve the protective effect for the cables and optical cables. To ensure the initial water absorption rate, the adhesive content in the water-blocking yarn formula is usually low. As a result, the highly absorbent resin in the water-blocking yarn coating is partially exposed to the air, causing the water-blocking yarn to easily absorb moisture, become sticky, and shed powder during use. The environmental humidity needs to be controlled during subsequent production and use, which undoubtedly increases production costs. Moreover, due to the low adhesive content, the water-absorbing component and the matrix have poor bonding, and the water-blocking capacity of each area varies greatly. In addition, the currently used water-absorbing resin layer has the problem of low water condensation, resulting in a short service life of the cable. Summary of the Invention

[0004] In response to the many problems of the above-mentioned water-blocking yarn due to the low adhesive content and the small amount of condensed water, the present invention provides an expandable water-blocking non-woven fabric for cables, and its preparation method and application. The water-blocking non-woven fabric uses a cellulose sponge with high water absorption, which not only has a high amount of condensed water, but also can serve as a sealing layer for the water-absorbing resin, reducing the amount of adhesive used and preventing the water-absorbing resin from being exposed and powdered.

[0005] In order to achieve the above object, the present invention provides a method for preparing an expandable water-blocking non-woven fabric for cables, which comprises the following steps:

[0006] S1, dissolving microcrystalline cellulose in an alkaline solution, then adding a pore-forming agent, freeze-drying to obtain a cellulose sponge, and then compressing and shaping it to a thickness of less than 3 mm;

[0007] S2, blending spandex staple fibers and polyester staple fibers, combing the fibers and then needle-punching the fibers to obtain a spandex-polyester nonwoven fabric;

[0008] S3, coating the surface of the prepared spandex-polyester non-woven fabric with water-absorbent resin powder, and then fixing the compressed and shaped cellulose sponge on the side of the spandex-polyester non-woven fabric coated with the water-absorbent resin powder by needle punching to form a cellulose sponge layer;

[0009] S4. Covering the cover non-woven fabric coated with an adhesive on the cellulose sponge layer, and hot pressing to obtain a water-absorbing and swellable non-woven fabric.

[0010] In this technical solution, the absorbent resin powder and cellulose sponge serve as the absorbent materials, combining both water-absorbing and water-blocking functions. They absorb water while also expanding to block subsequent water ingress. The hydrogen bonds within the cellulose sponge interact with those within the spandex fibers of the nonwoven fabric, effectively enhancing the bond between the absorbent material and the nonwoven substrate. The cellulose sponge's high expansion ratio and water retention not only provide a water-blocking effect, but also provide a favorable humidity environment for the expansion of the absorbent resin powder, thereby enhancing the water-blocking properties of the water-blocking nonwoven fabric and extending its service life.

[0011] Preferably, in step S1, the alkaline solution is a mixed solution of urea and sodium hydroxide or a mixed solution of urea and potassium hydroxide, the concentration of urea in the mixed solution is 80-100 g / L, and the concentration of sodium hydroxide or potassium hydroxide is 100-120 g / L.

[0012] The role of alkaline solution is to dissolve cellulose. The mechanism is: the hydrated ion radius of the alkali metal ions in the alkali solution is very small, which makes it easier for them to enter the cellulose, open the hydrogen bonds, and destroy the mutual forces, making the cellulose dissolve in the alkali solution.

[0013] Preferably, in step S1, the pore-forming agent is anhydrous sodium sulfate, anhydrous calcium chloride, anhydrous magnesium chloride or polyvinyl alcohol, with a particle size of 0.125-0.18 mm. Compared with 100 g of microcrystalline cellulose, the added amount is 120-140 g.

[0014] The function of the pore former is to occupy a certain volume to form pores. After subsequent washing or solvent removal, the sodium sulfate will be removed, leaving the pores.

[0015] Preferably, in step S2, the length of the spandex and polyester staple fibers is 12-15 cm, and the combing speed is 10-30 m / min.

[0016] Preferably, in step S2, the spandex-polyester non-woven fabric has a thickness of 1.2-2.0 mm and a gram weight of 25-30 g / m2.

[0017] Preferably, in step S3, the water-absorbing resin powder is a copolymer of methyl acrylate and vinyl acetate, the ratio is (2-3):1, and the amount used is 40-50 g / m2.

[0018] The advantages of copolymers of methyl acrylate and vinyl acetate over other water-absorbing resins are:

[0019] (1) Excellent mechanical properties: Copolymers generally have good toughness and strength, can withstand large external forces without breaking easily, and are suitable for applications that need to withstand mechanical stress.

[0020] (2) Excellent weather resistance: The copolymer has strong resistance to ultraviolet rays and environmental factors, can maintain stability in outdoor environments, and is suitable for outdoor applications.

[0021] (3) Good water absorption: Compared with other resins, the copolymer of methyl acrylate and vinyl acetate performs well in water absorption and can effectively absorb water, making it suitable for hydrogels and water-absorbing materials.

[0022] Preferably, in step S3, the adhesive is vinyl acetate acrylic latex or styrene acrylic latex, and the amount used is 20-30 g / m2.

[0023] Specifically, in step S4, the hot pressing conditions are 70-80° C., 20-30 MPa, 20-30 min, and ambient humidity ≤30%.

[0024] A second aspect of the present invention provides an expandable water-blocking nonwoven fabric produced by the above-mentioned preparation method.

[0025] A third aspect of the present invention provides use of the above-mentioned expandable water-blocking non-woven fabric in the preparation of cables.

[0026] Through the above technical solution, the present invention achieves the following beneficial effects:

[0027] The present invention utilizes water-absorbing resin powder and cellulose sponge as the absorbent materials, combining both water-absorbing and water-blocking functions. It absorbs water while also expanding to block subsequent water ingress. The hydrogen bonds within the cellulose sponge interact with those within the spandex fibers of the nonwoven fabric, effectively enhancing the bonding strength between the absorbent material and the nonwoven fabric substrate. The cellulose sponge boasts a high expansion ratio and excellent water retention, providing both its own water-blocking properties and a favorable humidity environment for the expansion of the water-absorbing resin powder. This enhances the water-blocking properties of the water-blocking nonwoven fabric, while also extending its service life. DETAILED DESCRIPTION

[0028] The following is a detailed description of the specific embodiments of the present invention in conjunction with the examples. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0029] Example 1

[0030] The preparation method of the water-blocking nonwoven fabric includes:

[0031] S1. Dissolve 100 g of microcrystalline cellulose in a solution containing 80 g / L urea and 120 g / L sodium hydroxide, then add 140 g of anhydrous sodium sulfate, freeze-dry, and prepare a cellulose sponge. Compress and shape the sponge to a thickness of less than 3 mm.

[0032] S2. Combing spandex staple fibers and polyester staple fibers with a length of 12 to 15 cm in a carding machine at a speed of 30 m / min for 20 min, and then needle-punching to obtain a spandex-polyester non-woven fabric having a thickness of 1.2 mm and a gram weight of 25 g / m2;

[0033] S3, coating the surface of the prepared spandex-polyester non-woven fabric with 30g of methyl acrylate and 10g of vinyl acetate copolymer, and then fixing the compressed and shaped cellulose sponge on the side of the spandex-polyester non-woven fabric coated with the water-absorbent resin powder by needle punching to form a cellulose sponge layer;

[0034] S4. Covering the cellulose sponge layer with a cover non-woven fabric coated with 20 g of vinyl acetate latex or styrene acrylic latex, and hot pressing to obtain a water-absorbing and swellable non-woven fabric.

[0035] Example 2

[0036] The preparation method of the water-blocking nonwoven fabric includes:

[0037] S1. Dissolve 100 g of microcrystalline cellulose in a solution containing 100 g / L urea and 100 g / L sodium hydroxide, then add 120 g of anhydrous sodium sulfate, freeze-dry to obtain a cellulose sponge, and then compress and shape it to a thickness of less than 3 mm.

[0038] S2. Combing spandex staple fibers and polyester staple fibers with a length of 12 to 15 cm in a carding machine at a speed of 10 m / min for 25 min, and then needle-punching to obtain a spandex-polyester non-woven fabric having a thickness of 2.0 mm and a gram weight of 30 g / m2;

[0039] S3, coating the surface of the prepared spandex-polyester non-woven fabric with 20g of methyl acrylate and 10g of vinyl acetate copolymer, and then fixing the compressed and shaped cellulose sponge on the side of the spandex-polyester non-woven fabric coated with the water-absorbent resin powder by needle punching to form a cellulose sponge layer;

[0040] S4. Covering the cellulose sponge layer with a cover non-woven fabric coated with 25 g of vinyl acetate latex or styrene acrylic latex, and hot pressing to obtain a water-absorbing and swellable non-woven fabric.

[0041] Example 3

[0042] The preparation method of the water-blocking nonwoven fabric includes:

[0043] S1. Dissolve 100 g of microcrystalline cellulose in a solution containing 80 g / L urea and 120 g / L potassium hydroxide, then add 130 g of anhydrous calcium chloride, freeze-dry to obtain a cellulose sponge, and then compress and shape it to a thickness of less than 3 mm.

[0044] S2. Combing spandex staple fibers and polyester staple fibers with a length of 12 to 15 cm in a carding machine at a speed of 20 m / min for 20 min, and then needle-punching to obtain a spandex-polyester non-woven fabric having a thickness of 1.6 mm and a gram weight of 28 g / m2;

[0045] S3, coating the surface of the prepared spandex-polyester non-woven fabric with 30g of methyl acrylate and 10g of vinyl acetate copolymer, and then fixing the compressed and shaped cellulose sponge on the side of the spandex-polyester non-woven fabric coated with the water-absorbent resin powder by needle punching to form a cellulose sponge layer;

[0046] S4. Covering the cellulose sponge layer with a cover non-woven fabric coated with 25 g of vinyl acetate latex or styrene acrylic latex, and hot pressing to obtain a water-absorbing and swellable non-woven fabric.

[0047] Comparative Example 1

[0048] Other conditions were the same as in Example 1, except that no cellulose sponge was used.

[0049] Comparative Example 2

[0050] Other conditions are the same as in Example 1, except that no water-absorbing resin is used.

[0051] Performance Testing

[0052] The nonwoven fabrics prepared in the Examples and Comparative Examples were subjected to the following performance tests: water swelling rate, water swelling height, and moisture content were measured according to GB / T 18944.1-2003, "Porous Polymer Elastomer Sponges and Porous Rubber Products," Part 1: Sheet Testing. Tensile strength was measured according to GB / T 20027.1-2016, "Rubber or Plastic Coated Fabrics - Determination of Bursting Strength," Part 1: Steel Ball Method.

[0053] Long-term stability: Test the water-blocking expansion rate after placing it in a 90°C environment for 24 hours.

[0054] The results are shown in Table 1.

[0055] Table 1 Performance test results

[0056]

[0057] From Table 1 we can see that:

[0058] (1) The water-blocking expansion speed, expansion height and moisture content of the non-woven fabric made by using water-absorbent resin powder and cellulose sponge at the same time are much higher than those of the non-woven fabric made by using water-absorbent resin powder or cellulose sponge alone, and higher than the sum of the two. This shows that there is a synergistic effect between the water-absorbent resin powder and the cellulose sponge (this is because the porous structure of the cellulose sponge can provide a large surface area, so that water molecules can more effectively contact the water-absorbent resin. This structure can enhance the retention and transfer of water in the material. When the water-absorbent resin powder absorbs water in the pores of the cellulose sponge, it can help enhance the water absorption capacity of the sponge itself. This combination effect makes the two together to form a greater water storage capacity.), which greatly improves the water absorption and water-blocking properties of the non-woven fabric;

[0059] (2) The tensile strength of non-woven fabrics made by using both water-absorbent resin powder and cellulose sponge is good. This is because the water-absorbent resin powder can form a certain cross-linking structure in the non-woven fabric, and through the combination with the cellulose sponge, it enhances the overall mechanical properties of the material. This cross-linking can improve the tensile strength of the non-woven fabric, making it less likely to break when stretched. The water-absorbent resin powder can be evenly dispersed in the cellulose sponge during the preparation process, preventing local concentration, thereby effectively improving the uniformity of the force applied to the non-woven fabric and also improving the tensile strength.

[0060] (3) The water-blocking expansion rate of the non-woven fabric made by using both water-absorbent resin powder and cellulose sponge in Example 1 decreased by 15% after being treated at 90°C for 24 hours, while that of the non-woven fabric made by using only water-absorbent resin powder or cellulose sponge decreased by 25%, respectively. This indicates that the synergistic effect of water-absorbent resin powder and cellulose sponge can not only enhance the water absorption capacity of the product, but also extend its service life.

[0061] The preferred embodiments of the present invention are described in detail above in conjunction with the embodiments. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0062] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0063] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing an expandable water-blocking nonwoven fabric for cables, characterized in that: The steps include: S1, dissolving microcrystalline cellulose in an alkaline solution, then adding a pore-forming agent, freeze-drying to obtain a cellulose sponge, and then compressing to set the sponge; S2, blending spandex staple fibers and polyester staple fibers, combing the fibers and then needle-punching the fibers to obtain a spandex-polyester nonwoven fabric; S3, coating the surface of the prepared spandex-polyester non-woven fabric with water-absorbent resin powder, and then fixing the compressed and shaped cellulose sponge on the side of the spandex-polyester non-woven fabric coated with the water-absorbent resin powder by needle punching to form a cellulose sponge layer; S4. Covering the cover non-woven fabric coated with an adhesive on the cellulose sponge layer, and hot pressing to obtain a water-absorbing and swellable non-woven fabric.

2. The preparation method according to claim 1, characterized in that In step S1, the alkaline solution is a mixed solution of urea and sodium hydroxide or a mixed solution of urea and potassium hydroxide, the concentration of urea in the mixed solution is 80-100 g / L, and the concentration of sodium hydroxide or potassium hydroxide is 100-120 g / L.

3. The preparation method according to claim 1, characterized in that In step S1, the pore-forming agent is anhydrous sodium sulfate with a particle size of 0.125-0.18 mm. Compared with 100 g of microcrystalline cellulose, the added amount is 120-140 g.

4. The preparation method according to claim 1, characterized in that In step S2, the length of the spandex and polyester staple fibers is 12-15 cm, and the combing speed is 10-30 m / min.

5. The preparation method according to claim 1, characterized in that In step S2, the spandex-polyester non-woven fabric has a thickness of 1.2-2.0 mm and a gram weight of 25-30 g / m2.

6. The preparation method according to claim 1, characterized in that In step S3, the water-absorbing resin powder is a copolymer of methyl acrylate and vinyl acetate, the ratio is (2-3):1, and the amount used is 40-50 g / m2.

7. The preparation method according to claim 1, characterized in that In step S3, the adhesive is vinyl acetate latex or styrene acrylic latex, and the amount used is 20-30 g / m2.

8. The preparation method according to claim 1, characterized in that In step S4, the hot pressing conditions are 70-80° C., 20-30 MPa, 20-30 min, and ambient humidity ≤30%.

9. The expandable water-blocking nonwoven fabric produced by the method according to any one of claims 1 to 8.

10. Use of the expandable water-blocking nonwoven fabric according to claim 9 in the preparation of cables.

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