Expansion water-blocking non-woven fabric for cable as well as preparation method and application thereof

Abstract

The invention discloses an expansion water-blocking non-woven fabric for a cable and a preparation method and application thereof, and the preparation method comprises the following steps: S1, dissolving microcrystalline cellulose in an alkaline solution, then adding a pore-forming agent, freeze-drying to prepare cellulose sponge, and then compressing and shaping; s2, blending spandex short fibers and polyester short fibers, carding the blended spandex short fibers and polyester short fibers, and performing needling forming to obtain spandex-polyester non-woven fabric; s3, coating the surface of the prepared spandex-terylene non-woven fabric with water-absorbent resin powder, and then fixing compressed and shaped cellulose sponge on the surface, coated with the water-absorbent resin powder, of the spandex-terylene non-woven fabric by a needling method to form a cellulose sponge layer; and S4, covering the cellulose sponge layer with the covering layer non-woven fabric coated with the adhesive, and performing hot pressing to obtain the water-swelling non-woven fabric. The water-absorbing resin powder and the cellulose sponge are used as water-absorbing materials, so that the water-absorbing and water-blocking functions are achieved, water can be absorbed, and subsequent water entering can be blocked through expansion.

Description

Technical Field

[0001] The invention relates to a water-blocking material, in particular to an expanded water-blocking nonwoven 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 will cause the aging and cracking of the cable outer covering. Therefore, the development of cable outer covering non-woven fabrics with water absorption and water blocking functions is imperative. Now, water-blocking powder (sodium polyacrylate, polyvinyl alcohol, carboxymethyl cellulose, etc.) with super absorbent resin as the main component is mostly 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 gel, blocking all possible water seepage channels, thereby providing completely reliable sealing and waterproof performance. For example, patent CN111172760A discloses a high expansion rate water-blocking yarn and its production process. The water-blocking yarn includes fibers, an adhesive layer formed on the surface of the fiber, 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 of the adhesive content, while the water absorption and expansion performance of the coating material is affected by the content of highly absorbent resin. When the adhesive content is high, the strength of the coating material is higher, but the dense surface formed wraps the highly absorbent resin, which easily inhibits the expansion performance of the coating, resulting in a decrease in the initial water absorption rate, causing unqualified indicators and failing to achieve the protective effect on cables and optical cables. In order to ensure the initial water absorption rate, the adhesive content in the water-blocking yarn formula is usually low, and 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 and become sticky, and lose powder during use. The environmental humidity needs to be controlled during subsequent production and use, which undoubtedly pushes up the production cost. Moreover, because the adhesive content is low, the water-absorbing component and the matrix are not well bonded, and the water-blocking capacity of each area varies greatly. In addition, the currently used water-absorbing resin layer has the problem of small condensation amount, resulting in a short service life of the cable. Summary of the invention

[0004] In view of the many problems of the above-mentioned water-blocking yarn due to low adhesive content and small condensation amount, the present invention provides an expandable water-blocking non-woven fabric for cables and a preparation method and application thereof. The water-blocking non-woven fabric adopts cellulose sponge with high water absorption, which not only has high condensation amount, but also can be used as a sealing layer for water-absorbing resin, thereby reducing the amount of adhesive used and avoiding exposure and powdering of the water-absorbing resin.

[0005] In order to achieve the above object, the present invention provides a method for preparing a swellable water-blocking nonwoven fabric for a cable, which comprises the following steps: 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 control the thickness to be less than 3 mm; 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 adhesive on the cellulose sponge layer, and obtaining a water-absorbing and swellable non-woven fabric by heat pressing.

[0006] In the above technical solution, water-absorbent resin powder and cellulose sponge are used as water-absorbent materials, which have both water-absorbing and water-blocking functions. They can absorb water and block the subsequent entry of water by expansion. The hydrogen bonds in the cellulose sponge interact with the hydrogen bonds in the spandex fibers of the non-woven fabric, effectively improving the bonding strength between the water-absorbent material and the non-woven fabric matrix. The cellulose sponge has a good expansion multiple and water storage effect. It not only has a water-blocking effect itself, but also provides a good humidity environment for the expansion of the water-absorbent resin powder, thereby improving the water-blocking performance of the water-blocking non-woven fabric and having a long service life.

[0007] 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.

[0008] The role of alkaline solution is to dissolve cellulose. The mechanism is: the hydrated ion radius of alkali metal ions in the alkali solution is very small, so it is easier to enter cellulose, open hydrogen bonds, and destroy the interaction between them, so that cellulose dissolves in the alkali solution. Preferably, in step S1, the pore-forming agent is anhydrous sodium sulfate, anhydrous calcium chloride, anhydrous magnesium chloride or polyvinyl alcohol, and has a particle size of 0.125-0.18 mm. Compared with 100 g of microcrystalline cellulose, the added amount is 120-140 g.

[0009] 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.

[0010] Preferably, in step S2, the spandex and polyester staple fibers have a length of 12-15 cm, and the combing speed is 10-30 m / min.

[0011] 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.

[0012] 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 / ㎡.

[0013] The advantages of copolymers of methyl acrylate and vinyl acetate over other water-absorbing resins are: (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.

[0014] (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.

[0015] (3) Good water absorption: Compared with other resins, copolymers of methyl acrylate and vinyl acetate perform well in water absorption and can effectively absorb water, making them suitable for hydrogels and absorbent materials.

[0016] Preferably, in step S3, the adhesive is vinyl acetate latex or styrene acrylic latex, and the amount used is 20-30 g / m2.

[0017] Specifically, in step S4, the hot pressing conditions are 70-80° C., 20-30 MPa, 20-30 min, and ambient humidity ≤30%.

[0018] The second aspect of the present invention provides an expandable water-blocking nonwoven fabric obtained by the above-mentioned preparation method.

[0019] A third aspect of the present invention provides use of the above-mentioned expandable water-blocking nonwoven fabric in the preparation of cables.

[0020] Through the above technical solution, the present invention achieves the following beneficial effects: The present invention uses water-absorbing resin powder and cellulose sponge as water-absorbing materials, which have both water-absorbing and water-blocking functions. It can absorb water and block the subsequent entry of water by expansion. The hydrogen bonds in the cellulose sponge interact with the hydrogen bonds in the spandex fibers of the non-woven fabric, effectively improving the bonding strength between the water-absorbing material and the non-woven fabric substrate. The cellulose sponge has a good expansion multiple and water storage effect. It not only has a water-blocking effect itself, but also provides a good humidity environment for the expansion of the water-absorbing resin powder, thereby improving the water-blocking performance of the water-blocking non-woven fabric, and has a long service life. DETAILED DESCRIPTION

[0021] The specific implementation of the present invention is described in detail below in conjunction with the examples. It should be understood that the specific implementation described herein is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0022] Example 1 The preparation method of the water-blocking nonwoven fabric comprises: S1, dissolving 100g of microcrystalline cellulose in a solution containing 80g / L urea and 120g / L sodium hydroxide, then adding 140g of anhydrous sodium sulfate, freeze-drying to obtain a cellulose sponge, and then compressing and shaping it to control the thickness to be less than 3mm; S2, combing the 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 forming them by needle punching to obtain a spandex-polyester non-woven fabric, the spandex-polyester non-woven fabric having a thickness of 1.2 mm and a gram weight of 25 g / ㎡; 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; S4. Cover the cellulose sponge layer with a cover non-woven fabric coated with 20 g of vinyl acetate latex or styrene acrylic latex, and obtain a water-absorbing and swellable non-woven fabric by hot pressing.

[0023] Example 2 The preparation method of the water-blocking nonwoven fabric comprises: S1, dissolving 100g of microcrystalline cellulose in a solution containing 100g / L urea and 100g / L sodium hydroxide, then adding 120g of anhydrous sodium sulfate, freeze-drying to obtain a cellulose sponge, and then compressing and shaping it to control the thickness to be less than 3mm; S2, combing the 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 forming them by needle punching to obtain a spandex-polyester non-woven fabric, the spandex-polyester non-woven fabric having a thickness of 2.0 mm and a gram weight of 30 g / ㎡; 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; S4. Cover the cellulose sponge layer with a cover non-woven fabric coated with 25 g of vinyl acetate latex or styrene acrylic latex, and obtain a water-absorbing and swellable non-woven fabric by hot pressing.

[0024] Example 3 The preparation method of the water-blocking nonwoven fabric comprises: S1, dissolving 100g of microcrystalline cellulose in a solution containing 80g / L urea and 120g / L potassium hydroxide, then adding 130g of anhydrous calcium chloride, freeze-drying to obtain a cellulose sponge, and then compressing and shaping it to control the thickness to be less than 3mm; S2, combing the 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 forming them by needle punching to obtain a spandex-polyester non-woven fabric, the spandex-polyester non-woven fabric having a thickness of 1.6 mm and a gram weight of 28 g / ㎡; 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; S4. Cover the cellulose sponge layer with a cover non-woven fabric coated with 25 g of vinyl acetate latex or styrene acrylic latex, and obtain a water-absorbing and swellable non-woven fabric by hot pressing.

[0025] Comparative Example 1 Other conditions were the same as in Example 1, except that no cellulose sponge was used.

[0026] Comparative Example 2 Other conditions are the same as in Example 1, except that no water-absorbing resin is used.

[0027] Performance Testing The nonwoven fabrics prepared in the examples and comparative examples were subjected to the following performance tests: According to GB / T 18944.1-2003 "Porous polymer elastic material sponges and porous rubber products" Part 1: Sheet test water barrier swelling rate, water barrier swelling height, and moisture content. According to GB / T 20027.1-2016 "Determination of bursting strength of rubber or plastic coated fabrics" Part 1: Steel ball method to measure tensile strength.

[0028] Long-term stability: Test the water-blocking expansion rate after placing in a 90°C environment for 24 hours.

[0029] The results are shown in Table 1.

[0030] Table 1 Performance test results

[0031] From Table 1 we can see that: (1) The water-blocking swelling speed, swelling 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 indicates 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, allowing water molecules to contact the water-absorbent resin more effectively. 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 combined effect makes the two combined to form a greater water storage capacity.), which greatly improves the water absorption and water-blocking properties of the non-woven fabric; (2) The tensile strength of the non-woven fabric made by using 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, the overall mechanical properties of the material are enhanced. 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 to prevent local concentration, thereby effectively improving the force uniformity of the non-woven fabric and also improving the tensile strength.

[0032] (3) After the non-woven fabric made of water-absorbent resin powder and cellulose sponge in Example 1 was treated at 90°C for 24 hours, the water-blocking expansion rate decreased by 15%, while the non-woven fabric made of water-absorbent resin powder or cellulose sponge alone decreased by 25%, respectively. This shows 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.

[0033] The preferred implementation modes of the present invention are described in detail above in combination with the embodiments; however, the present invention is not limited to the specific details in the above implementation modes. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical scheme of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0034] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0035] In addition, 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 a swellable 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 shape; 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 adhesive on the cellulose sponge layer, and obtaining a water-absorbing and swellable non-woven fabric by heat pressing.

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, anhydrous calcium chloride, anhydrous magnesium chloride or polyvinyl alcohol, and the particle size is 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 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 / ㎡.

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 obtained by the preparation 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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