A method for preparing multi-layer composite fabric

Abstract

The present invention relates to a method for preparing a fabric, and in particular to a method for preparing a multilayer composite fabric. The present invention adopts a new PTFE membrane modification method, wherein plasma surface treatment increases polar groups on the surface of the PTFE membrane, and acyl chloride-modified nanoparticles form covalent bonds with the PTFE membrane and the polyimide fabric, thereby improving the bonding strength between the composite fabrics and greatly improving the moisture permeability and air permeability of the composite fabrics.

Description

Technical Field

[0001] The invention relates to a method for preparing a fabric, and in particular to a method for preparing a multi-layer composite fabric. Background Art

[0002] Composite fabrics of polyimide (PI) fabrics and polytetrafluoroethylene (PTFE) membranes have shown great potential in high-end protective clothing, filter materials, and special environmental applications due to their unique combination of properties. PI fabrics are known for their excellent heat resistance, mechanical strength, and chemical stability, while PTFE membranes are favored for their excellent chemical resistance, low friction coefficient, and excellent electrical insulation properties. Combining these two materials through lamination technology can create a new type of composite fabric that has high strength, high temperature resistance, excellent chemical stability, and good air and moisture permeability. This composite fabric has broad application prospects in the fields of protective equipment, filter membranes, and high-performance textiles.

[0003] Although the composite fabric of PI fabric and PTFE membrane has many advantages, there are still some technical problems that need to be solved in its preparation process. Among them, the most critical problem is the low surface energy characteristics of PTFE membrane, which makes it difficult to achieve strong adhesion when it is laminated with PI fabric. The prior art uses chemical reagents such as sodium naphthalene to modify the surface of PTFE membrane to improve its bonding performance. However, sodium naphthalene is a highly corrosive chemical. Using this method not only poses the risk of environmental pollution, but also has an adverse effect on the moisture permeability and air permeability of PTFE membrane, thereby limiting the use of composite fabrics in application scenarios that require high air permeability and moisture permeability. Therefore, developing an environmentally friendly and efficient PTFE membrane surface modification method to achieve its strong adhesion with PI fabric, while maintaining or even improving the moisture permeability and air permeability of the composite fabric, has become an important direction of current research. Summary of the invention

[0004] In view of the above problems, the present invention provides a novel method for preparing a multi-layer composite fabric, which improves the moisture permeability and air permeability of the composite fabric while ensuring the bonding strength between the PTFE membrane and the polyimide fabric.

[0005] Specifically, the present invention provides a method for preparing a multilayer composite fabric, wherein the multilayer composite fabric includes a PTFE film layer located on both sides, a polyimide layer, and an acyl chloride-modified nanoparticle layer and a copolyamide hot melt adhesive layer located between the two layers. The method includes the following steps:

[0006] (A) Preparation of PTFE membrane by biaxial stretching: A PTFE film with a microfiber structure is prepared by heating, extrusion, biaxial stretching and heat setting steps;

[0007] (B) Preparing polyimide fabric: providing polyimide fabric of required size and thickness;

[0008] (C) Plasma surface treatment: placing the PTFE membrane prepared by the biaxial stretching method in a plasma surface treatment device and treating it at a power of 50-200 W for 1-10 minutes to increase the polar groups on the surface of the PTFE membrane;

[0009] (D) Coating of acyl chloride-modified nanoparticles: 1-3 g / m2 of nanoparticles were uniformly coated on the surface of the plasma-treated PTFE membrane. 2 The acyl chloride-modified nanoparticles form a coating layer;

[0010] (E) Lamination: Align the PTFE membrane coated with acyl chloride-modified nanoparticles with the polyimide fabric and apply 2-5 g / m 2 The copolyamide hot melt adhesive is then laminated at a temperature of 120-180°C and a pressure of 0.15-0.8MPa to obtain a laminated composite fabric of the PTFE membrane and the polyimide fabric.

[0011] As a preferred embodiment, the specific steps of preparing the PTFE membrane by biaxial stretching method include:

[0012] (1) heating the PTFE resin to 327-350°C to soften it;

[0013] (2) Extruding the softened PTFE resin into a sheet through an extrusion device;

[0014] (3) placing the PTFE resin sheet into a biaxial stretching machine, and simultaneously stretching it longitudinally and transversely at a temperature of 220-320° C., with a stretching ratio of 2-15 times, to form a PTFE film with a fine fiber structure;

[0015] (4) The biaxially stretched PTFE film is subjected to heat setting treatment at a temperature of 200-360° C. for 30 seconds to 10 minutes.

[0016] As a preferred embodiment, the acyl chloride-modified nanoparticles are porous nanoparticles, specifically one or more of porous silica, porous alumina or porous barium titanate, and the particle size range is 50-200 nm.

[0017] As a preferred embodiment, the steps for preparing the acyl chloride-modified nanoparticles include:

[0018] (1) Select the type of nanoparticles;

[0019] (2) adding the selected nanoparticles to a toluene solution containing pyridine and phosphorus trichloride, setting the reaction temperature to 40-80° C. and the reaction time to 2-6 h;

[0020] (3) The porous nanoparticles after the reaction are washed and dried to obtain acyl chloride-modified porous nanoparticles.

[0021] As a preferred embodiment, in the toluene solution, the mass concentration of pyridine is 0.01-0.04wt%, and the mass concentration of phosphorus trichloride is 2-8wt%.

[0022] As a preferred embodiment, the thickness of the PTFE membrane is 0.05-0.2 mm, and the thickness of the polyimide fabric is 0.1-0.3 mm.

[0023] As a preferred embodiment, the power of the plasma surface treatment is 100 W and the treatment time is 5 minutes.

[0024] As a preferred embodiment, in the lamination step, the lamination temperature is set to 150° C., the lamination time is set to 2-5 minutes, and the lamination pressure is set to 0.5 MPa.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] First, the present invention adopts a new PTFE membrane modification method. Plasma surface treatment increases the polar groups on the surface of the PTFE membrane. The acyl chloride-modified nanoparticles form covalent bonds with the PTFE membrane and the polyimide fabric, thereby improving the bonding strength between the composite fabrics.

[0027] Secondly, the specific modification method of PTFE avoids the pollution problem caused by the treatment of PTFE membrane with sodium naphthalene and the micropore deformation problem of the membrane, and the porous nanoparticles modified with acyl chloride provide additional breathable and moisture permeable channels, thereby greatly improving the moisture permeability and breathability of the composite fabric. DETAILED DESCRIPTION

[0028] Example 1

[0029] A method for preparing a multi-layer composite fabric, the specific steps are as follows:

[0030] (A) Preparation of PTFE membrane by biaxial stretching:

[0031] (A1) heating the PTFE resin to 338° C. to soften it;

[0032] (A2) extruding the softened PTFE resin into a sheet through an extrusion device;

[0033] (A3) placing a PTFE resin sheet in a biaxial stretching machine, and simultaneously stretching it longitudinally and transversely at a temperature of 270° C., with a stretching ratio of 8 times, to form a PTFE film having a fine fiber structure;

[0034] (A4) The biaxially stretched PTFE film was subjected to heat setting treatment at 280° C. for 5 minutes. The thickness of the obtained PTFE film was 0.1 mm.

[0035] (B) Preparing polyimide fabric: Provide polyimide fabric of required size and thickness of 0.2 mm.

[0036] (C) Plasma surface treatment: The PTFE membrane prepared by the biaxial stretching method was placed in a plasma surface treatment device and treated at a power of 100 W for 5 minutes to increase the polar groups on the surface of the PTFE membrane.

[0037] (D) Coating of acyl chloride-modified nanoparticles;

[0038] (D1) Select porous silica nanoparticles with a particle size of 100 nm;

[0039] (D2) adding the selected nanoparticles to a toluene solution containing pyridine and phosphorus trichloride, wherein the mass concentration of pyridine is 0.025wt%, the mass concentration of phosphorus trichloride is 5wt%, and the reaction temperature is set to 60°C.

[0040] The reaction time is 4h;

[0041] (D3) washing and drying the porous nanoparticles after the reaction to obtain acyl chloride-modified porous silica nanoparticles.

[0042] (D4) 2g / m2 was uniformly coated on the surface of the plasma treated PTFE membrane. 2 The porous silica nanoparticles are modified with acyl chloride to form a coating layer.

[0043] (E) Lamination: Align the PTFE membrane coated with acyl chloride-modified nanoparticles with the polyimide fabric and apply 3 g / m 2 The polyamide hot melt adhesive is then laminated at a temperature of 150° C. and a pressure of 0.5 MPa. The lamination time is set to 3 minutes to obtain a laminated composite fabric of the PTFE membrane and the polyimide fabric.

[0044] Example 2

[0045] This embodiment differs from Embodiment 1 in that step (C) plasma surface treatment is omitted.

[0046] Example 3

[0047] This example differs from Example 1 in that step (D) of coating the acyl chloride-modified nanoparticles is omitted.

[0048] Example 4

[0049] The difference between this embodiment and embodiment 1 is that nanoparticles which are not modified with acyl chloride are used in step (D).

[0050] The test samples of Examples 1-4 were tested for peel strength, moisture permeability, air permeability and hydrostatic pressure resistance under the same test conditions. The results are shown in Table 1.

[0051] Table 1

[0052]

[0053] While the present invention has been shown and described in connection with the embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A method for preparing a multi-layer composite fabric, characterized in that The following steps are involved: (A) Preparation of PTFE membrane by biaxial stretching: A PTFE film with a microfiber structure is prepared by heating, extrusion, biaxial stretching and heat setting steps; (B) Preparation of polyimide fabric: Provide polyimide fabric of required size and thickness; (C) Plasma surface treatment: Place the PTFE membrane prepared by biaxial stretching in a plasma surface treatment device and treat it at a power of 50-200W for 1-10 minutes to increase the polar groups on the surface of the PTFE membrane; (D) Coating of acyl chloride-modified nanoparticles: Evenly coat 1-3g / m² of acyl chloride-modified nanoparticles on the surface of the plasma-treated PTFE membrane. to form a coating layer; (E) lamination: aligning the PTFE membrane coated with acyl chloride-modified nanoparticles with the polyimide fabric, applying 2-5 g / m² of copolyamide hot melt adhesive between the two, and then laminating at a temperature of 120-180°C and a pressure of 0.15-0.8 MPa to obtain a laminated composite fabric of the PTFE membrane and the polyimide fabric; the acyl chloride-modified nanoparticles are porous nanoparticles, specifically selected from one or more of porous silica, porous alumina or porous barium titanate; the preparation steps of the acyl chloride-modified nanoparticles include: (1) selecting the type of nanoparticles; (2) adding the selected nanoparticles to a toluene solution containing pyridine and phosphorus trichloride, setting the reaction temperature to 40-80°C and the reaction time to 2-6 hours; (3) washing and drying the porous nanoparticles after the reaction to obtain acyl chloride-modified porous nanoparticles.

2. The method according to claim 1, characterized in that The specific steps of preparing PTFE membrane by biaxial stretching method include: (1) heating PTFE resin to 327-350°C to soften it; (2) extruding the softened PTFE resin into thin sheets through an extrusion device; (3) placing the thin sheet of PTFE resin into a biaxial stretching machine, and stretching it longitudinally and transversely at a temperature of 220-320°C at a stretching multiple of 2-15 times to form a PTFE film with a fine fiber structure; (4) heat-setting the biaxially stretched PTFE film at a temperature of 200-360°C for 30 seconds to 10 minutes.

3. The method according to claim 1, characterized in that The particle size range of the acyl chloride-modified nanoparticles is 50-200 nm.

4. The method according to claim 1, characterized in that: In the toluene solution, the mass concentration of pyridine is 0.01-0.04wt%, and the mass concentration of phosphorus trichloride is 2-8wt%.

5. The method according to claim 1, characterized in that: The thickness of the PTFE film is 0.05-0.2 mm, and the thickness of the polyimide fabric is 0.1-0.3 mm.

6. The method according to claim 1, characterized in that The power of the plasma surface treatment is 100 W, and the treatment time is 5 minutes.

7. The method according to claim 1, characterized in that In the lamination step, the lamination temperature was set to 150° C., the lamination time was set to 2-5 minutes, and the lamination pressure was set to 0.5 MPa.

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