A process for preparing microcapsules and a functional finishing process for nonwoven fabrics

Abstract

This invention relates to the technical field of functional finishing of nonwoven fabrics, specifically to a microcapsule preparation process and a functional finishing process for nonwoven fabrics. The microcapsule preparation process includes the following steps: dissolving bisphenol A in an aqueous sodium hydroxide solution to prepare a mixed solution; dissolving polytetrafluoroethylene emulsion and a water- and oil-repellent agent in a mixed solution of hexamethylene diisocyanate and trichloroethane; slowly and completely adding the mixed trichloroethane emulsion to the sodium hydroxide and bisphenol A mixed solution, stirring thoroughly to ensure uniform dispersion; heating the uniformly dispersed mixed solution to 45-55°C, causing hexamethylene diisocyanate and bisphenol A to undergo a condensation reaction at the particle interface, forming microcapsules with polyurethane as the wall material and a water- and oil-repellent agent as the core material. The microcapsules of this invention, used in the finishing process of nonwoven fabrics, can improve the stability of the treatment agent dispersion, while simultaneously improving the compatibility between components, the water- and oil-repellent properties of the woven fabric, and production efficiency.

Description

Technical Field

[0001] This invention relates to the technical field of functional finishing of nonwoven fabrics, specifically to a microcapsule preparation process and a functional finishing process for nonwoven fabrics. Background Technology

[0002] Nonwoven fabric is a type of fabric that does not require spinning or weaving. Instead, it is a new type of fiber product that is soft, breathable, and has a planar structure, formed by arranging short or long textile fibers in a directional or random manner to form a web structure, and then reinforcing it using mechanical, thermal bonding, or chemical methods.

[0003] Functional finishing is one of the main processes in nonwoven fabric production lines. Nonwoven materials produced using conventional processes often suffer from defects such as poor surface smoothness, poor oxidation resistance, and lack of water and oil resistance due to limitations in raw materials and processing technology, making them unsuitable for direct application. Therefore, nonwoven materials need to be combined with finishing agents or other functional materials through physical or chemical methods to improve their performance.

[0004] Traditional nonwoven fabric finishing mainly involves impregnating the nonwoven fabric with a treatment agent, followed by oven drying for setting. Currently, the main component of the treatment agents used in nonwoven fabric finishing is a water- and oil-repellent agent. This component is poorly soluble in water and is mainly processed as an emulsion. However, the dispersion stability of the emulsion is not high, and it often breaks down or precipitates due to the addition of other components. The solid content in the emulsion changes during production, becoming one of the key factors affecting the product's oil- and water-repellent properties. The quality of the mixed emulsion becomes unstable after long-term storage. Furthermore, the water- and oil-repellent properties only apply to the surface of the nonwoven fabric. Using an impregnation method to coat the entire nonwoven fabric with the treatment agent results in high agent consumption. Completely wetted nonwoven fabric material requires even more heat energy for drying, impacting electrical energy consumption and production capacity. Summary of the Invention

[0005] To address the issues of poor oil and water repellency and uniformity in existing nonwoven fabrics, this invention provides a microcapsule preparation process and a nonwoven fabric functional finishing process.

[0006] In a first aspect, the present invention provides a process for preparing microcapsules, comprising the following steps: (1) Dissolve bisphenol A in an aqueous sodium hydroxide solution to prepare a mixed solution for later use; The structural formula of bisphenol A is ; (2) Dissolve polytetrafluoroethylene emulsion and waterproof and oil-repellent agent in a mixed solution of hexamethylene diisocyanate and trichloroethane to obtain trichloroethane emulsion; (3) Add all the mixed trichloroethane emulsion to the sodium hydroxide and bisphenol A mixed solution in step (1) and stir thoroughly to disperse evenly; (4) Heat the uniformly dispersed solution from step (3) to 45-55°C to allow hexamethylene diisocyanate and bisphenol A to undergo a polycondensation reaction at the particle interface, forming microcapsules with polyurethane as the wall material and waterproof and oil-resistant agent as the core material.

[0007] Furthermore, in step (1), the concentration of bisphenol A is 40%-60%, the concentration of sodium hydroxide solution is 30%-40%, and the volume ratio of bisphenol A solution to sodium hydroxide solution is 1-2:5.

[0008] Furthermore, in step (2), the solid content of the polytetrafluoroethylene emulsion is 50%-65%, the particle size is 0.15μm-0.2μm, and the pH value is 9.5-10.5; the solid content of the waterproof and oil-repellent agent is 30%-40%; the solid content of the hexamethylene diisocyanate is 30%-50%; the solid content of the trichloroethane solution is 40%-60%; the mass ratio of the waterproof and oil-repellent agent to the polytetrafluoroethylene emulsion is 0.95-1:1; and the mass ratio of the trichloroethane solution to the hexamethylene diisocyanate is 2-2.5:1.

[0009] Furthermore, in step (2), the waterproof and oil-repellent agent is at least one of the following: paraffin-aluminum soap waterproof and oil-repellent agent, pyridine quaternary ammonium salt waterproof and oil-repellent agent, hydroxymethyl melamine derivative waterproof and oil-repellent agent, stearate chromium complex waterproof and oil-repellent agent, organosilicon waterproof and oil-repellent agent, and fluorine-based waterproof and oil-repellent agent.

[0010] Furthermore, in step (4), the mixed solution is heated by water bath heating or direct heating.

[0011] Furthermore, the microcapsules prepared in step (4) have a particle size of 1-200 μm, preferably 1-50 μm.

[0012] Secondly, the present invention provides a functional finishing process for nonwoven fabrics, specifically by covering at least one side of a nonwoven fabric material with microcapsules prepared by the above-mentioned preparation process, and drying to obtain the finished nonwoven fabric.

[0013] Furthermore, the microcapsules can be coated by spraying, scraping, or dipping.

[0014] Furthermore, the amount of microcapsules sprayed is 0.1%-10% of the finished felt material.

[0015] Furthermore, the drying temperature is 200-300℃, and the drying time is 1-30 minutes.

[0016] The beneficial effects of this invention are as follows: by optimizing the chemical treatment of nonwoven fabrics through microencapsulation finishing technology, functional substances and related polymer compounds are encapsulated and sealed by physical and chemical methods to produce solid particles with a particle diameter of 1-200 μm that are stable under normal conditions; the original basic properties of the microparticles are not lost and can be released at high temperatures; the dispersion stability and compatibility between components are improved; at the same time, the water and oil repellency and uniformity of nonwoven fabrics are improved, the consumption of various treatment agents and electrical energy is reduced, and the production efficiency is improved. Detailed Implementation

[0017] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0018] Example 1 A process for preparing microcapsules includes the following steps: (1) Dissolve 20 mL of 50% bisphenol A solution in 50 mL of 40% dilute sodium hydroxide solution; (2) Dissolve 4g of polytetrafluoroethylene emulsion with a solid content of 60% (particle size 0.15μm-0.17μm, pH value about 10) and 3.8g of waterproof and oil-repellent agent (Chuanhua E6) with a solid content of 38% in 10g of hexamethylene diisocyanate with a solid content of 40% and 24g of trichloroethane solution with a solid content of 50% and mix to obtain trichloroethane emulsion; (3) Slowly drip the trichloroethane emulsion into the mixed solution of sodium hydroxide and bisphenol A in step (1), and stir thoroughly to disperse it evenly; (4) Heat the uniformly dispersed mixed solution to 50°C in a water bath to allow hexamethylene diisocyanate and bisphenol A to undergo a condensation reaction at the particle interface to form microcapsules with polyurethane as the wall material and waterproof and oil-proof agent as the core material.

[0019] The microcapsules were sprayed onto the front surface of the nonwoven fabric, with a coating amount of 2.5% of the mass of the finished nonwoven fabric. After spraying, the fabric was dried in a high-temperature oven at 230°C for 5 minutes to obtain the finished nonwoven fabric.

[0020] The finished nonwoven fabric was tested for waterproof and oil-proof properties. The waterproof performance was rated as level 4, and the oil-proof performance was rated as level 4.

[0021] Comparative Example 1 12 kg of polytetrafluoroethylene emulsion with a solid content of 60% and 11.5 kg of waterproof and oil-repellent agent (Chuanhua E6) with a solid content of 38% were dissolved in 276.5 kg of water and stirred evenly to make a solution. The non-woven fabric was then impregnated in the solution and the excess emulsion was pressed out by a rolling mill. The fabric was then dried in an oven at 230°C for 5 minutes. After drying, the adhesive content was controlled at about 2.5% to obtain the finished non-woven fabric.

[0022] The finished nonwoven fabric was tested for waterproof and oil-proof properties. The waterproof performance was rated as level 2, and the oil-proof performance was rated as level 1.

[0023] It can be seen that the waterproof and oil-proof properties of the finished nonwoven fabric obtained in Example 1 are significantly better than those in Comparative Example 1; moreover, it reduces the consumption of various treatment agents.

[0024] Example 2 A process for preparing microcapsules includes the following steps: (1) Dissolve 20 mL of 40% bisphenol A in 50 mL of 30% dilute sodium hydroxide aqueous solution; (2) Dissolve 4g of polytetrafluoroethylene emulsion with a solid content of 50% (particle size 0.15μm-0.17μm, pH value about 10) and 3.8g of waterproof and oil-repellent agent (Chuanhua E6) with a solid content of 40% in 10g of hexamethylene diisocyanate with a solid content of 40% and 24g of trichloroethane solution with a solid content of 50% and mix to obtain trichloroethane emulsion; (3) Slowly drip the trichloroethane emulsion into the mixed solution of sodium hydroxide and bisphenol A in step (1), and stir thoroughly to disperse it evenly; (4) Heat the uniformly dispersed mixed solution to 50°C in a water bath to allow hexamethylene diisocyanate and bisphenol A to undergo a condensation reaction at the particle interface to form microcapsules with polyurethane as the wall material and waterproof and oil-proof agent as the core material.

[0025] The microcapsules were sprayed onto the front surface of the nonwoven fabric material, with a coating amount of 3% of the mass of the finished nonwoven fabric material. After spraying, the material was dried in a high-temperature oven at 230°C for 5 minutes to obtain the finished nonwoven fabric material.

[0026] The finished nonwoven fabric material was tested for waterproof and oil-proof properties. The waterproof performance was rated as level 3, and the oil-proof performance was rated as level 3.

[0027] Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention.

Claims

1. A process for preparing microcapsules, characterized in that, Includes the following steps: (1) Dissolve bisphenol A in an aqueous sodium hydroxide solution to prepare a mixed solution for later use; (2) Dissolve polytetrafluoroethylene emulsion and waterproof and oil-repellent agent in a mixed solution of hexamethylene diisocyanate and trichloroethane to obtain trichloroethane emulsion; (3) Add all the mixed trichloroethane emulsion to the sodium hydroxide and bisphenol A mixed solution in step (1) and stir thoroughly to disperse evenly; (4) Heat the uniformly dispersed solution from step (3) to 45-55°C to allow hexamethylene diisocyanate and bisphenol A to undergo a polycondensation reaction at the particle interface, forming microcapsules with polyurethane as the wall material and waterproof and oil-proof agent as the core material. The prepared microcapsules are coated on at least one side of the nonwoven fabric material and dried to obtain the finished nonwoven fabric; the coating method of the microcapsules is spraying.

2. The preparation process according to claim 1, characterized in that, In step (1), the concentration of bisphenol A is 40%-60%, the concentration of sodium hydroxide solution is 30%-40%, and the volume ratio of bisphenol A solution to sodium hydroxide solution is 1-2:

5.

3. The preparation process according to claim 1, characterized in that, In step (2), the solid content of the polytetrafluoroethylene emulsion is 50%-65%, the particle size is 0.15μm-0.2μm, and the pH value is 9.5-10.5; the solid content of the waterproof and oil-repellent agent is 30%-40%; the solid content of the hexamethylene diisocyanate is 30%-50%; the solid content of the trichloroethane solution is 40%-60%; the mass ratio of the waterproof and oil-repellent agent to the polytetrafluoroethylene emulsion is 0.95-1:1; and the mass ratio of the trichloroethane solution to the hexamethylene diisocyanate is 2-2.5:

1.

4. The preparation process according to claim 1, characterized in that, In step (2), the waterproof and oil-repellent agent is at least one of the following: paraffin-aluminum soap waterproof and oil-repellent agent, pyridine quaternary ammonium salt waterproof and oil-repellent agent, hydroxymethyl melamine derivative waterproof and oil-repellent agent, chromium stearate complex waterproof and oil-repellent agent, organosilicon waterproof and oil-repellent agent, and fluorine-based waterproof and oil-repellent agent.

5. The preparation process according to claim 1, characterized in that, In step (4), the mixed solution is heated by water bath heating or direct heating.

6. The preparation process according to claim 1, characterized in that, The microcapsules prepared in step (4) have a particle size of 1-200 μm.

7. The preparation process according to claim 1, characterized in that, The coverage of microcapsules is 0.1%-10% of the finished felt material.

8. The preparation process according to claim 1, characterized in that, The drying temperature is 200-300℃, and the drying time is 1-30 minutes.