CN116219741A - Preparation method of conductive and electromagnetic shielding crosslinked dendrimer silver-plated meta-aramid fiber - Google Patents

Abstract

The invention discloses a preparation method of conductive and electromagnetic shielding crosslinked dendrimer silver-plated meta-aramid fiber, which comprises the following steps: adding ultra-pure water into hyperbranched polyamide-amine, dissolving, then dripping a cross-linking agent, magnetically stirring in a constant-temperature water bath, and performing cross-linking reaction to obtain hyperbranched polyamide-amine solution; extracting the aramid fiber with absolute ethyl alcohol, washing, drying, immersing in hyperbranched polyamide-amine solution, drying to obtain cross-linked hyperbranched polyamide-amine modified meta-aramid fiber, immersing in silver ammonia solution, starting ultrasonic treatment, carrying out silver ion ultrasonic adsorption, maintaining ultrasonic treatment after adsorption, dropwise adding glucose solution dropwise for ultrasonic reduction, standing, filtering, washing with ultrapure water, and vacuum drying to obtain the product. According to the invention, hyperbranched polyamide-amine is utilized to modify meta-aramid fiber, active sites capable of being combined with metal particles are added, silver plating meta-aramid fiber with excellent conductivity and electromagnetic shielding performance is obtained by chemical silver deposition, the plating layer is firmly bonded with fiber, and the mechanical property is kept good.

Description

Preparation method of conductive and electromagnetic shielding cross-linked dendrimers silver-plated meta-aramid fibers

technical field

The invention relates to silver-plated fibers, in particular to a preparation method for conductive and electromagnetic shielding cross-linked dendrimers silver-plated meta-aramid fibers.

Background technique

The full name of meta-aramid is polym-phenylene isophthalamide, commonly known as "aramid 1313", and the English abbreviation is PMIA. Its structure is composed of at least 85% of amide bonds directly connected with two benzene rings. The molecules show a strong three-dimensional network structure of hydrogen bonds, thus exhibiting excellent heat resistance, thermal stability, dimensional stability, self-extinguishing flame retardancy, electrical insulation, chemical stability, radiation resistance and outstanding Mechanical properties, etc., so it has great application value in aerospace, rail transit, high temperature filtration, electrical insulation, construction, marine fire protection, sports cars, protection and other fields.

However, in various flammable and explosive working environments, clothing made of flame-retardant meta-aramid fiber can easily cause static electricity on its surface due to its high insulation, and generate electric sparks, thereby causing explosion accidents. At the same time, non-anti-electric/magnetic meta-aramid protective clothing makes workers engaged in electronic equipment suffer from health damage due to electromagnetic radiation. Therefore, protective clothing with a single function can no longer meet complex needs, and multifunctional protective clothing with flame retardant, antistatic, and electromagnetic shielding needs to be solved urgently.

Conductive aramid is a high-performance material that eliminates static electricity through electron conduction and corona discharge. It usually refers to a material with a resistivity lower than 10 ⁸ Ω·cm at 20°C and 65% relative humidity in a standard state, and the resistivity reaches 10~ 10 ^-3 Ω·cm conductive aramid can shield electromagnetic waves.

Due to the ubiquitous excellent electrical conductivity of metals, metallizing the surface of PMIA can make it have the functions of eliminating static electricity, conducting electricity, and electromagnetic shielding. The realization of PMIA surface metallization not only shows the characteristics of metal, but also maintains the flexibility of PMIA, and has the advantages of being lighter, cheaper and more flexible than metal. The current surface metallization methods of aramid fibers mainly include electroless plating, sputtering plating, vacuum deposition, surface coating and blend spinning methods. Among them, the electroless plating method of surface metallization has become one of the most effective methods for depositing metal on meta-aramid due to its moderate cost, uniform coating on various substrates, and simple and convenient equipment. However, the reported electroless plating preparation of conductive materials has the disadvantages of relatively large mechanical damage to the aramid fiber and weak plating.

Contents of the invention

Aiming at the problems of large mechanical damage to the existing aramid metal coating fiber and weak coating, the invention provides a method for preparing conductive and electromagnetic shielding cross-linked dendrimers silver-plated meta-aramid fibers, the steps of which are: (1) to Add ultrapure water to the hyperbranched polyamidoamine, heat and stir to make it completely dissolve and disperse, drop in the crosslinking agent, stir in a constant temperature water bath with magnetic force, and carry out the crosslinking reaction to obtain a crosslinked hyperbranched polyamidoamine solution, keep it warm for later use (2) extract the aramid fiber with absolute ethanol, wash and dry it, then immerse it in the cross-linked hyperbranched polyamide-amine solution obtained in step (1), take it out and dry to obtain the cross-linked hyperbranched polyamido-amine Modified meta-aramid fiber; (3) immerse the cross-linked hyperbranched polyamide-amine modified meta-aramid fiber obtained in step (2) in the silver-ammonia solution, turn on the ultrasound, and carry out ultrasonic adsorption of silver ions. After the adsorption is completed, keep Ultrasound, add glucose solution drop by drop for ultrasonic reduction, stand still, filter, wash the filtrate with ultrapure water, and dry it in vacuum to obtain the cross-linked dendritic silver-coated meta-aramid fiber.

The aramid fibers used in the present invention can be aramid fiber filaments, staple fibers, or aramid non-woven fabrics or aramid woven fabrics.

The present invention specifically adopts the following process parameters to optimize the above-mentioned method, or to obtain a cross-linked dendrimer silver-plated meta-aramid fiber with excellent performance.

In step (1), the number-average molecular weight of the hyperbranched polyamidoamine is 500-1000, and the concentration is 0.5-40g/L. The hyperbranched polyamidoamine is a highly irregular structure containing a large number of holes and terminal primary amino functional groups. Branched spherical new three-dimensional macromolecules with unique physical and chemical properties. At present, hyperbranched polyamidoamines, which are easy to synthesize, low in cost, and can be produced in large quantities, have good applications in coating curing agents, drug carriers, sewage treatment, catalysts, molecular recognition, self-assembly, surfactants, and conductive materials. Therefore, the meta-aramid fiber/fabric is selected as the base material, and the hyperbranched polyamide-amine with highly branched and surface multifunctional functional groups is used as the surface modifier, which can introduce a large number of active sites on the surface of the fiber/fabric , while improving the mechanical and flexibility properties, followed by electroless silver plating as a secondary reaction platform to prepare conductive and electromagnetic shielding meta-aramid fibers/fabrics, which can effectively solve the damage to the mechanical properties of fibers/fabrics caused by electroless plating, The disadvantages are high cost of modifying reagents and poor adhesion between coating and fiber/fabric.

The crosslinking agent of the present invention is one of monoepoxy compounds, diepoxy compounds, diglycidyl esters or polyepoxy compounds. Specifically, the monoepoxide compound is epichlorohydrin, epibromohydrin or glycidyl acid; the diepoxide compound is diglycidyl ether, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether ether, 1,4-butanediol diglycidyl ether, poly(propylene glycol diglycidyl ether), bisphenol A diglycidyl ether, resorcinol diglycidyl ether, or poly(dimethylsiloxane) di Glycidyl ethers; diglycidyl esters are diglycidyl phthalate, diglycidyl adipate or diglycidyl aniline; polyepoxides are glycerol triglycidyl ether or pentaerythritol glycidyl ether . The molar ratio of crosslinking agent to hyperbranched polyamidoamine is (0.1-12):1; the crosslinking reaction time is 0.5-12h; the water bath temperature is 10-100°C, and the magnetic stirring rate is 120-2400rpm.

In step (2), the soaking time is 0.5-6h. In step (3), the ultrasonic frequency is 40KHz, the power is 120-360W, the ultrasonic adsorption time is 0.1-3h, and the ultrasonic reduction time is 0.5-4h; the vacuum drying temperature is 30-90°C, and the time is 6-24h.

The present invention can use the existing silver ammonia solution, but as a better choice, the invention provides a preparation method of the silver ammonia solution: drip ammonia water drop by drop into the silver nitrate aqueous solution to make the solution clear and transparent, and use hydrogen Potassium oxide adjusts the pH of the solution to 10-13, and continues to drop ammonia water to make the mixed solution clear and transparent again, and finally adds polyvinylpyrrolidone K30 to obtain silver ammonia solution. Wherein, the concentration of the silver nitrate aqueous solution is 5-40g/L, the concentration of potassium hydroxide is 3-9g/L, and the concentration of polyvinylpyrrolidone is 1-10g/L.

The composition of the glucose solution compatible with the above-mentioned silver ammonia solution is: 10-50g/L anhydrous glucose, 20-60mL/L absolute ethanol, and 60-90mg/L polyethylene glycol 2000; the glucose solution The dropping rate is 0.5-3 drops/second.

The present invention uses the cross-linked hyperbranched polyamide-amine to modify the meta-aramid through the surface physical coating modification method, which significantly increases the active sites that can be combined with metal particles, improves the mechanical properties, and improves The chemical reagent is cheap; the invention obtains the silver-plated meta-aramid fiber with excellent conductivity and electromagnetic shielding performance through chemical deposition of silver, the coating layer is firmly bonded to the fiber, the mechanical properties are kept good, and the experimental steps are simple and easy.

Description of drawings

Fig. 1 is the PMIA virgin fiber cleaned up in embodiment 2, the modified fiber PMIA/HP ₅ EGDE ₃ in embodiment 2, the PMIA/Ag fiber in comparative example 1, and the silver-plated fiber PMIA/Ag fiber in embodiment 2 SEM image of HP ₅ EGDE ₃ /Ag.

Fig. 2 is the PMIA virgin fiber cleaned up in embodiment 2, the modified fiber PMIA/HP ₅ EGDE ₃ in embodiment 2, the PMIA/Ag fiber in comparative example 1, and the silver-plated fiber PMIA/Ag fiber in embodiment 2 Atomic force microscopy image of HP ₅ EGDE ₃ /Ag.

FIG. 3 is the XRD pattern of the cleaned PMIA fiber in Example 13, the modified fiber PMIA/HP ₅ DGDE ₂ , the silver-plated fiber PMIA/HP ₅ DGDE ₂ /Ag, and the PMIA/Ag in Comparative Example 1.

Fig. 4 is the PMIA raw fiber cleaned up in embodiment 13, the modified fiber PMIA/HP ₅ DGDE ₂ in embodiment 13, the PMIA/Ag fiber in comparative example 1, and the silver-plated fiber PMIA/ in embodiment 13 Mechanical property analysis chart of HP ₅ DGDE ₂ /Ag.

Fig. 5 is a thermal weight loss curve of the cleaned PMIA fiber, modifier HP ₅ ECH ₂ , modified fiber PMIA/HP ₅ ECH ₂ , and silver-plated fiber PMIA/HP ₅ ECH ₂ /Ag in Example 14.

Fig. 6 is embodiment 1-7, the surface resistivity analysis figure of the conductive fiber that embodiment 2 and 8-12 and comparative example 1 prepare (Fig. 6A is embodiment 1, embodiment 2, embodiment 3 successively from left to right , embodiment 4, embodiment 5, embodiment 6, embodiment 7; Fig. 6B is embodiment 8, embodiment 9, embodiment 2, embodiment 10, embodiment 11, embodiment 12, rectangular Shading is Comparative Example 1).

FIG. 7 is an analysis diagram of the firmness of the silver layer on the surface of the PMIA/HP ₅ EGDE ₅ /Ag fiber in Example 11.

Fig. 8 is the PMIA raw fabric that cleans up in embodiment 16, the modified fabric PMIA/HP ₅ DGDE ₃ , the PMIA/Ag fabric in comparative example 2, and the silver-plated fabric PMIA/HP ₅ DGDE ₃ /Ag of embodiment 16 scanning electron microscope image.

9 is the sheet resistance value of the silver-plated fabric PMIA/HP ₅ DGDE ₃ /Ag in Example 16.

Fig. 10 is the electromagnetic shielding effectiveness value of the silver-plated fabric PMIA/HP ₅ DGDE ₃ /Ag in Example 16.

Detailed ways

The present invention is described below in conjunction with examples, which are only used to explain the present invention and are not intended to limit the scope of the present invention.

The hyperbranched polyamide-amine used in the embodiment of the present invention is provided by Weihai Chenyuan Molecular New Material Co., Ltd., and the model is CYD-D014.

Example 1

A method for preparing conductive and electromagnetic shielding cross-linked dendritic silver-plated meta-aramid fibers, comprising the following steps:

1. Preparation of crosslinked hyperbranched polyamide-amine modifier

Add 50mL of ultrapure water (1g/L) to 0.05g of hyperbranched polyamidoamine (HPAMAM), heat and stir at 60°C to fully dissolve and disperse evenly; Glycol diglycidyl ether (EGDE), the molar ratio of EGDE to HPAMAM is 3:1, and the cross-linking reaction is carried out in a constant temperature water bath at 80°C and magnetic stirring at a speed of 360rpm for 1h, and the cross-linking modification reaction solution HP ₁ is obtained. EGDE ₃ .

2. Pretreatment of meta-aramid fibers

The meta-aramid fiber (PMIA) was placed in a Soxhlet extractor, extracted with absolute ethanol for 18 hours, and then vacuum-dried at 60°C for 8 hours.

3. Preparation of cross-linked hyperbranched polyamide-amine modified meta-aramid fibers

Soak 0.5g of the PMIA fiber pre-treated in step 2 in the HP ₁ EGDE ₃ mixture in step 1, carry out the fiber surface modification reaction at room temperature for 2 hours, and then dry it in vacuum at 60°C for 8 hours to obtain the modified meta-aramid fiber Fiber PMIA/HP ₁ EGDE ₃ .

4. Preparation of cross-linked hyperbranched polyamide-amine silver-coated conductive meta-aramid fibers

Add ammonia water drop by drop to 50mL 15g/L silver nitrate aqueous solution until the solution is clear and transparent, then adjust the pH of the solution to 12.0 with 8g/L KOH aqueous solution, continue to drop ammonia water to make the solution clear and transparent again, add 0.35g polyvinylpyrrolidone K30 (PVP), fully stirred to make it dissolve completely, and obtained silver ammonia solution;

Add 0.0042g of polyethylene glycol 2000 (PEG) and 2mL of absolute ethanol to 1.2g of anhydrous glucose, stir initially, and then add ultrapure water to 50mL to prepare a glucose reduction solution;

Immerse 0.25g of PMIA/HP ₁ EGDE ₃ prepared in step 3 into the silver ammonia solution, ultrasonically adsorb for 0.5h at 35°C, the ultrasonic frequency is 40KHz, and the power is 240W; The original solution was ultrasonically reduced for 0.5h at 30°C, the frequency was 40KHz, and the power was 240W; it was left to stand for a period of time to allow the silver particles to fully deposit on the fibers; then the fibers were filtered and washed with ultrapure water for 3 times until the The solution was no longer turbid; finally, the silver-plated fiber was placed in a vacuum drying oven at 60°C for 8 hours to obtain PMIA/HP ₁ EGDE ₃ /Ag conductive fiber.

Example 2

The only difference from Example 1 is: in step 1, the concentration of HPAMAM is 5g/L, and the obtained silver-plated conductive meta-aramid fiber is PMIA/HP ₅ EGDE ₃ /Ag.

Example 3

The only difference from Example 1 is: in step 1, the concentration of HPAMAM is 10g/L, and the obtained silver-plated conductive meta-aramid fiber is PMIA/HP ₁₀ EGDE ₃ /Ag.

Example 4

The only difference from Example 1 is: in step 1, the concentration of HPAMAM is 15g/L, and the obtained silver-plated conductive meta-aramid fiber is PMIA/HP ₁₅ EGDE ₃ /Ag.

Example 5

The only difference from Example 1 is: in step 1, the concentration of HPAMAM is 20g/L, and the obtained silver-plated conductive meta-aramid fiber is PMIA/HP ₂₀ EGDE ₃ /Ag.

Example 6

The only difference from Example 1 is: in step 1, the concentration of HPAMAM is 25g/L, and the obtained silver-plated conductive meta-aramid fiber is PMIA/HP ₂₅ EGDE ₃ /Ag.

Example 7

The only difference from example 1 is: in step 1, the concentration of HPAMAM is 30g/L, and the obtained silver-plated conductive meta-aramid fiber is PMIA/HP ₃₀ EGDE ₃ /Ag.

Example 8

A method for preparing conductive and electromagnetic shielding cross-linked dendritic silver-plated meta-aramid fibers, comprising the following steps:

1. Preparation of crosslinked hyperbranched polyamide-amine modifier

Add 50mL ultrapure water (5g/L) to 0.25g of HPAMAM, heat and stir at 65°C to make it fully dissolve and disperse evenly; then add 0.049mL EGDE dropwise to the obtained HPAMAM aqueous solution, the molar ratio of EGDE to HPAMAM is 1 :1, and carry out the cross-linking reaction for 1 h in a constant temperature water bath at 65°C and magnetic stirring at a speed of 400 rpm to obtain a cross-linking modified reaction liquid HP ₅ EGDE ₁ .

2. Pretreatment of meta-aramid fibers

The PMIA was placed in a Soxhlet extractor, extracted with absolute ethanol for 12 hours, and then vacuum-dried at 60° C. for 8 hours.

3. Preparation of cross-linked hyperbranched polyamide-amine modified meta-aramid fibers

Soak 0.5g of the PMIA fiber pre-treated in step 2 in the HP ₅ EGDE ₁ mixture in step 1, carry out the fiber surface modification reaction at room temperature for 1 h, and then vacuum dry at 60°C for 10 h to obtain the modified meta-aramid fiber Fiber PMIA/HP ₅ EGDE ₁ .

4. Preparation of cross-linked hyperbranched polyamide-amine silver-coated conductive meta-aramid fibers

Add ammonia water drop by drop to 50mL 15g/L silver nitrate aqueous solution until the solution is clear and transparent, then adjust the pH of the solution to 12.0 with 8g/L KOH aqueous solution, continue to drop ammonia water to make the solution clear and transparent again, add 0.5g PVP, fully stirred to make it completely dissolved, and obtained silver ammonia solution;

Add 0.0045g of PEG and 2mL of absolute ethanol to 2.5g of anhydrous glucose, stir initially, and then add ultrapure water to 50mL to prepare a glucose reduction solution;

Immerse 0.25g of PMIA/HP ₅ EGDE ₁ prepared in step 3 into the silver ammonia solution, ultrasonically adsorb for 0.5h at 25°C, the ultrasonic frequency is 40KHz, and the power is 120W; The original solution was ultrasonically reduced at 25°C for 2 hours, the frequency was 40KHz, and the power was 120W; it was left to stand for a period of time to allow the silver particles to fully deposit on the fiber; No more turbidity; finally put the silver-plated fiber into a vacuum drying oven at 60° C. for 8 hours to obtain PMIA/HP ₅ EGDE ₁ /Ag conductive fiber.

Example 9

The only difference from Example 8 is that in step 1, the molar ratio of EGDE to HPAMAM is 2:1, and the obtained silver-plated conductive meta-aramid fiber is PMIA/HP ₅ EGDE ₂ /Ag.

Example 10

The only difference from Example 8 is that in step 1, the molar ratio of EGDE to HPAMAM is 4:1, and the obtained silver-plated conductive meta-aramid fiber is PMIA/HP ₅ EGDE ₄ /Ag.

Example 11

The only difference from Example 8 is that in step 1, the molar ratio of EGDE to HPAMAM is 5:1, and the obtained silver-plated conductive meta-aramid fiber is PMIA/HP ₅ EGDE ₅ /Ag.

Example 12

The only difference from Example 8 is that in step 1, the molar ratio of EGDE to HPAMAM is 6:1, and the obtained silver-plated conductive meta-aramid fiber is PMIA/HP ₅ EGDE ₆ /Ag.

Example 13

A method for preparing conductive and electromagnetic shielding cross-linked dendritic silver-plated meta-aramid fibers, comprising the following steps:

1. Preparation of crosslinked hyperbranched polyamide-amine modifier

Add 50mL of ultrapure water (5g/L) to 0.25g of HPAMAM, heat and stir at 40-80°C to fully dissolve and disperse evenly; then add 0.125mL of diethylene glycol diglycidol dropwise to the obtained HPAMAM aqueous solution Ether (DGDE), the molar ratio of DGDE to HPAMAM is 2:1, and the cross-linking reaction is carried out under constant temperature water bath at 80°C and magnetic stirring at 360rpm for 5 hours to obtain the cross-linking modification reaction solution HP ₅ DGDE ₂ .

2. Pretreatment of meta-aramid fibers

The PMIA was placed in a Soxhlet extractor, extracted with absolute ethanol for 15 hours, and then vacuum-dried at 60° C. for 8 hours.

3. Preparation of cross-linked hyperbranched polyamide-amine modified meta-aramid fiber

Soak 0.5g of the PMIA fabric pretreated in step 2 in the HP ₅ DGDE ₂ mixed solution in step 1, carry out the fabric surface modification reaction at room temperature for 0.5h, and then vacuum dry at 60°C for 8h to obtain the modified meta aromatic Polyamide fiber PMIA/HP ₅ DGDE ₂ .

4. Preparation of cross-linked hyperbranched polyamide-amine silver-coated conductive meta-aramid fibers

Add ammonia water drop by drop to 50mL 12g/L silver nitrate aqueous solution until the solution is clear and transparent, then use 6g/L KOH aqueous solution to adjust the pH of the solution to 11.0, continue to drop ammonia water to make the solution clear and transparent again, add 0.15g PVP, fully stirred to make it completely dissolved, and obtained silver ammonia solution;

Add 0.0035g of PEG and 1mL of absolute ethanol to 1.0g of anhydrous glucose, stir initially, and then add ultrapure water to 50mL to prepare a glucose reduction solution;

Immerse 0.25g of the PMIA/HP ₅ DGDE ₂ prepared in step 3 into the silver ammonia solution, ultrasonically adsorb at 30°C for 0.5h, the ultrasonic frequency is 40KHz, and the power is 252W; The original solution was ultrasonically reduced for 2 hours at 30°C, the frequency was 40KHz, and the power was 252W; it was left to stand for a period of time to allow the silver particles to fully deposit on the fiber; then the fiber was filtered and washed with ultrapure water for 3 times until the washing No more turbidity; finally put the silver-plated fiber into a vacuum drying oven at 60° C. for 8 hours to obtain PMIA/HP ₅ DGDE ₂ /Ag conductive fiber.

Example 14

A method for preparing conductive and electromagnetic shielding cross-linked dendritic silver-plated meta-aramid fibers, comprising the following steps:

1. Preparation of crosslinked hyperbranched polyamide-amine modifier

Add 50mL of ultrapure water (5g/L) to 0.25g of HPAMAM, heat and stir at 70°C to make it fully dissolve and disperse evenly; The molar ratio of HPAMAM to HPAMAM was 2:1, and the cross-linking reaction was carried out in a constant temperature water bath at 70°C and magnetic stirring at a speed of 300 rpm for 4 hours to obtain a cross-linking modification reaction liquid HP ₅ ECH ₂ .

2. Pretreatment of meta-aramid fibers

The PMIA was placed in a Soxhlet extractor, extracted with absolute ethanol for 12 hours, and then vacuum-dried at 60° C. for 8 hours.

3. Preparation of cross-linked hyperbranched polyamide-amine modified meta-aramid fibers

Soak 0.5g of the PMIA fiber pre-treated in step 2 in the HP ₅ ECH ₂ mixed solution in step 1, carry out the fiber surface modification reaction at room temperature for 3 hours, take it out after the reaction is over, make HP ₅ ECH ₂ solidify on the fiber surface, and then The fiber surface was washed with 1 g/L Na ₂ CO ₃ aqueous solution, and then vacuum-dried at 60° C. for 8 hours to obtain the modified meta-aramid fiber PMIA/HP ₅ ECH ₂ .

4. Preparation of cross-linked hyperbranched polyamide-amine silver-plated meta-aramid fiber for conductive and electromagnetic shielding

Add ammonia water drop by drop to 50mL 10g/L silver nitrate aqueous solution until the solution is clear and transparent, then adjust the pH of the solution to 10.0 with 4g/L KOH aqueous solution, continue to drop ammonia water to make the solution clear and transparent again, add 0.5g PVP, fully stirred to make it completely dissolved, and obtained silver ammonia solution;

Add 0.0030g of PEG and 3mL of absolute ethanol to 2.5g of anhydrous glucose, stir initially, and then add ultrapure water to 50mL to prepare a glucose reduction solution;

Immerse 0.25g of the PMIA/HP ₅ ECH ₂ prepared in step 3 into the silver ammonia solution, ultrasonically adsorb at 30°C for 2h, the ultrasonic frequency is 40KHz, and the power is 180W; then drop glucose reducing solution into it at a rate of 1 drop/second , and ultrasonic reduction at 30°C for 2 hours, the frequency is 40KHz, and the power is 180W; let it stand for a period of time, so that the silver particles are fully deposited on the fiber; then filter the fiber, wash the fiber with ultrapure water for 3 times, until the washing liquid is no longer Then cloudy; finally put the silver-plated fiber into a vacuum drying oven at 60° C. for 8 hours to obtain PMIA/HP ₅ ECH ₂ /Ag conductive fiber.

Example 15

A method for preparing conductive and electromagnetic shielding cross-linked dendritic silver-plated meta-aramid fibers, comprising the following steps:

1. Preparation of crosslinked hyperbranched polyamide-amine modifier

Add 100mL ultrapure water (5g/L) to 0.5g of HPAMAM, heat and stir at 60°C to make it fully dissolve and disperse evenly; then add 0.293mL EGDE dropwise to the obtained HPAMAM aqueous solution, the molar ratio of EGDE to HPAMAM is 3 :1, and carry out the cross-linking reaction for 2 hours in a constant temperature water bath at 60° C. and magnetic stirring at a speed of 240 rpm to obtain a cross-linking modified reaction liquid HP ₅ EGDE ₃ .

2. Pretreatment of meta-aramid fabric

The PMIA was placed in a Soxhlet extractor, extracted with absolute ethanol for 12 hours, and then vacuum-dried at 60° C. for 8 hours.

3. Preparation of cross-linked hyperbranched polyamide-amine modified meta-aramid fabric

Soak 1.0 g of the PMIA fabric pretreated in step 2 in the HP ₅ EGDE ₃ mixture in step 1, carry out the fabric surface modification reaction at room temperature for 1 h, and then vacuum dry at 60°C for 8 h to obtain the modified meta-aramid fiber Fabric PMIA/HP ₅ EGDE ₃ .

4. Preparation of cross-linked hyperbranched polyamide-amine silver-plated meta-aramid fabric for conductive and electromagnetic shielding

Add ammonia water drop by drop to 100mL 20g/L silver nitrate aqueous solution until the solution is clear and transparent, then adjust the pH of the solution to 11.0 with 6g/L KOH aqueous solution, continue to drop ammonia water to make the solution clear and transparent again, add 0.3g PVP, fully stirred to make it completely dissolved, and obtained silver ammonia solution;

Add 0.0065g of PEG and 2mL of absolute ethanol to 1.5g of anhydrous glucose, stir initially, and then add ultrapure water to 100mL to prepare a glucose reduction solution;

Immerse 0.5g of the PMIA/HP ₅ EGDE ₃ prepared in step 3 into the silver ammonia solution, ultrasonically adsorb at 30°C for 1h, the ultrasonic frequency is 40KHz, and the power is 120W; then drop glucose reducing solution into it at a rate of 2 drops/second , and ultrasonic reduction at 30°C for 1 hour, the frequency is 40KHz, and the power is 120W; let it stand for a period of time, so that the silver particles are fully deposited on the fabric; then filter the fabric, and wash the fabric 3 times with ultra-pure water until the washing liquid is no longer Then cloudy; finally put the silver-plated fabric into a vacuum drying oven at 60°C to dry for 8 hours to obtain a PMIA/HP ₅ EGDE ₃ /Ag conductive and electromagnetic shielding fabric.

Example 16

A method for preparing conductive and electromagnetic shielding cross-linked dendritic silver-plated meta-aramid fibers, comprising the following steps:

1. Preparation of crosslinked hyperbranched polyamide-amine modifier

Add 100mL ultrapure water (5g/L) to 0.5g of HPAMAM, heat and stir at 50°C to make it fully dissolve and disperse evenly; then add 0.374mL DGDE dropwise to the obtained HPAMAM aqueous solution, the molar ratio of DGDE to HPAMAM is 3 :1, and carry out the cross-linking reaction for 4 hours in a constant temperature water bath at 50° C. and magnetic stirring at a speed of 480 rpm to obtain a cross-linking modification reaction liquid HP ₅ DGDE ₃ .

2. Pretreatment of meta-aramid fabric

The PMIA was placed in a Soxhlet extractor, extracted with absolute ethanol for 12 hours, and then vacuum-dried at 60° C. for 8 hours.

3. Preparation of cross-linked hyperbranched polyamide-amine modified meta-aramid fabric

Soak 1.0 g of the PMIA fabric pretreated in step 2 in the HP ₅ DGDE ₃ mixture in step 1, carry out the fabric surface modification reaction at room temperature for 2 hours, and then vacuum dry at 60°C for 8 hours to obtain modified meta-aramid fiber Fabric PMIA/HP ₅ DGDE ₃ .

4. Preparation of cross-linked hyperbranched polyamide-amine silver-plated meta-aramid fabric for conductive and electromagnetic shielding

Add ammonia water drop by drop to 100mL 15g/L silver nitrate aqueous solution until the solution is clear and transparent, then adjust the pH of the solution to 11.0 with 5g/L KOH aqueous solution, continue to drop ammonia water to make the solution clear and transparent again, add 0.5g PVP, fully stirred to make it completely dissolved, and obtained silver ammonia solution;

Add 0.0060g of PEG and 1mL of absolute ethanol to 3.0g of anhydrous glucose, stir initially, and then add ultrapure water to 100mL to prepare a glucose reduction solution;

Immerse 0.5g of the PMIA/HP ₅ DGDE ₃ prepared in step 3 into the silver ammonia solution, ultrasonically adsorb at 30°C for 0.5h, the ultrasonic frequency is 40KHz, and the power is 252W; stock solution, and ultrasonically reduce it at 30°C for 2 hours, the frequency is 40KHz, and the power is 252W; let it stand for a period of time, so that the silver particles are fully deposited on the fabric; then filter the fabric, wash the fabric 3 times with ultrapure water, until the washing liquid No more turbidity; finally, place the silver-plated fabric in a vacuum drying oven at 60°C for 8 hours to obtain a PMIA/HP ₅ DGDE ₃ /Ag conductive and electromagnetic shielding fabric.

Example 17

A method for preparing conductive and electromagnetic shielding cross-linked dendritic silver-plated meta-aramid fibers, comprising the following steps:

1. Preparation of crosslinked hyperbranched polyamide-amine modifier

Add 100mL of ultrapure water (5g/L) to 0.5g of HPAMAM, heat and stir at 70°C to fully dissolve and disperse evenly; then drop 0.156mL of ECH into the obtained HPAMAM aqueous solution, and the molar ratio of ECH to HPAMAM is 3 :1, and carry out the cross-linking reaction for 2 hours in a constant temperature water bath at 70° C. and magnetic stirring at a speed of 240 rpm to obtain a cross-linking modification reaction liquid HP ₅ ECH ₃ .

2. Pretreatment of meta-aramid fabric

The PMIA was placed in a Soxhlet extractor, extracted with absolute ethanol for 12 hours, and then vacuum-dried at 60° C. for 8 hours.

3. Preparation of cross-linked hyperbranched polyamide-amine modified meta-aramid fabric

Soak 1.0g of the PMIA fabric pre-treated in step 2 in the HP ₅ ECH ₃ mixed solution in step 1, carry out the fabric surface modification reaction at room temperature for 1.5h, and then vacuum dry at 60°C for 8h to obtain the modified meta-position aromatic Polyamide fabric PMIA/HP ₅ ECH ₃ .

4. Preparation of cross-linked hyperbranched polyamide-amine silver-coated conductive meta-aramid fabric

Add ammonia water dropwise to 100mL 12g/L silver nitrate aqueous solution until the solution is clear and transparent, then adjust the pH of the solution to 10.0 with 5g/L KOH aqueous solution, continue to drop ammonia water to make the solution clear and transparent again, and add 0.25g PVP, fully stirred to make it completely dissolved, and obtained silver ammonia solution;

Add 0.0075g of PEG and 2mL of absolute ethanol to 3.0g of anhydrous glucose, stir initially, and then add ultrapure water to 100mL to prepare a glucose reduction solution;

Immerse 0.5g of the PMIA/HP ₅ ECH ₃ prepared in step 3 into the silver ammonia solution, ultrasonically adsorb at 30°C for 0.5h, the ultrasonic frequency is 40KHz, and the power is 252W; stock solution, and ultrasonically reduce it at 30°C for 1 hour, the frequency is 40KHz, and the power is 252W; let it stand for a period of time, so that the silver particles are fully deposited on the fabric; then filter the fabric, and wash the fabric 3 times with ultrapure water until the washing liquid No more turbidity; finally put the silver-plated fabric into a vacuum drying oven at 60° C. for 8 hours to obtain a PMIA/HP ₅ ECH ₃ /Ag conductive and electromagnetic shielding fabric.

Comparative example 1

The only difference from Example 1 is that steps 1 and 3 are not performed, and the meta-aramid fabric cleaned in step 2 is directly electroless-plated with silver to prepare PMIA/Ag fibers.

Comparative example 2

The only difference from Example 15 is that steps 1 and 3 are not performed, and the meta-aramid fabric cleaned in step 2 is directly electroless silver-plated to prepare PMIA/Ag fabric.

test 1

Use scanning electron microscope to observe in embodiment 2 clean PMIA original fiber, modified fiber PMIA/HP ₅ EGDE ₃ , PMIA/Ag in comparative example 1, and the silver-plated fiber PMIA/HP ₅ EGDE ₃ /Ag of embodiment 2 The surface morphology is shown in Figure 1. It can be seen from Figure 1 that the surface of PMIA is very clean, but there are some axial grooves. After modification, the surface grooves are covered by HP ₅ EGDE ₃ and become smooth. After further electroless silver plating, the silver layer is uniform and dense. The silver layer appears on the surface of the modified fiber, while the silver layer on the surface of the unmodified directly silver-plated fiber is discontinuous.

test 2

Use atomic force microscope to analyze the PMIA virgin fiber cleaned up in embodiment 2, the modified fiber PMIA/HP ₅ EGDE ₃ , the PMIA/Ag in comparative example 1, and the silver-plated fiber PMIA/HP ₅ EGDE ₃ /Ag of embodiment 2 The surface roughness is shown in Figure 2. It can be seen from Figure 2 that the roughness of the modified fabric is slightly reduced because the surface becomes smooth and smooth. After electroless plating, the roughness increases significantly due to the thick silver layer covering the surface of the fabric. Without modification The dents on the surface of the directly silver-plated fiber are filled with a small amount of silver particles and the roughness is reduced.

test 3

Carry out XRD analysis to the PMIA fiber cleaned in embodiment 13, modified fiber PMIA/HP ₅ DGDE ₂ , silver-plated fiber PMIA/HP ₅ DGDE ₂ /Ag, and PMIA/Ag in comparative example 1, the results are shown in Figure 3 . It can be seen from Figure 3 that PMIA has obvious diffraction peaks between 15° and 30°, indicating that the meta-aramid fibers are partially crystalline, and the crystallinity of the fibers increases after being modified by HP ₅ DGDE ₂ , and after silver plating, respectively The characteristic diffraction peaks of silver appear at 38.08°, 44.26°, 64.46°, 77.42°, and 81.58°, corresponding to the (111), (200), (220), (311) and (222) crystal planes of silver, respectively. (JCPDSNo.04-0783), and the characteristic diffraction peaks of the fibers are retained to a certain extent, but the PMIA characteristic diffraction peaks of the direct silver-plated fibers using PMIA are basically covered.

test 4

The PMIA fiber cleaned up in embodiment 13, the modified fiber PMIA/HP ₅ DGDE ₂ , the PMIA/Ag fiber in comparative example 1, and the silver-plated fiber PMIA/HP ₅ DGDE ₂ /Ag in embodiment 13 are mechanically Performance analysis, the results are shown in Figure 4. It can be seen from Fig. 4 that the tensile strength of PMIA/HP ₅ DGDE ₂ modified fiber and PMIA/HP ₅ DGDE ₂ /Ag silver-coated fiber are increased compared with the original PMIA, but the mechanical properties of PMIA/Ag are reduced, It shows that the modifier can protect the PMIA fiber from being corroded by the silver plating solution.

test 5

Characterize the thermal stability of the cleaned PMIA fiber, modifier HP ₅ ECH ₂ , modified fiber PMIA/HP ₅ ECH ₂ , and silver-plated fiber PMIA/HP ₅ ECH ₂ /Ag in embodiment 14, the results are shown in Figure 5 . It can be seen from Figure 5 that both the modified fiber and the silver-plated fiber maintain the good thermal stability of the original fiber.

test 6

The surface resistivity of the conductive fibers prepared in Examples 1-7, Examples 2 and 8-12 and Comparative Example 1 was tested, and the results are shown in FIG. 6 . It can be seen from Figure 6A that when the concentration of HPAMAM is 5g/L, the resistivity is the smallest and the conductivity is the best, which is 1.03×10 ^-4 Ω·cm; it can be seen from Figure 6B that when the molar ratio of EGDE to HPAMAM is 3 :1, the resistivity is the smallest, which is 1.03×10 ^-4 Ω·cm; while the direct silver-plated meta-aramid fiber has poor conductivity, and the resistivity is 7.81×10 ^-4 Ω·cm.

test 7

Example 11 was used to test the firmness of the silver layer on the surface of the PMIA/HP ₅ EGDE ₅ /Ag fiber, and the results are shown in FIG. 7 . It can be seen from Figure 7 that in the first 50 minutes of ultrasound, the silver layer is firmly bonded to the fiber, and even at 60 minutes the resistivity is only 2.98 times that before ultrasound.

test 8

Use a scanning electron microscope to observe the PMIA original fabric cleaned up in embodiment 16, the modified fabric PMIA/HP ₅ DGDE ₃ , the PMIA/Ag fabric in comparative example 2, and the silver-plated fabric PMIA/HP ₅ DGDE ₃ / of embodiment 16 The surface morphology of Ag, the results are shown in Figure 8. It can be seen from Figure 8 that the surface of the PMIA fabric is very smooth and clean, and the surface is covered by HP ₅ DGDE ₃ after modification. The silver layer on the surface of the silver fabric is loose and discontinuous.

test 9

A four-probe tester was used to investigate the conductivity of the silver-plated fabric PMIA/HP ₅ DGDE ₃ /Ag in Example 16, and the results are shown in FIG. 9 . It can be seen from Fig. 9 that the square resistance of the PMIA/HP ₅ DGDE ₃ /Ag fabric is as low as 10.14 mΩ/sq.

test 10

The electromagnetic shielding performance of the silver-plated fabric PMIA/HP ₅ DGDE ₃ /Ag in Example 16 was investigated using a vector network analyzer, and the results are shown in FIG. 10 . It can be seen from Figure 10 that the electromagnetic shielding effectiveness of the PMIA/HP ₅ DGDE ₃ /Ag fabric is as high as about 105dB.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (6)

1. The preparation method of the conductive and electromagnetic shielding crosslinked dendrimer silver-plated meta-aramid fiber is characterized by comprising the following steps of:

(1) Adding ultra-pure water into hyperbranched polyamide-amine, heating and stirring to completely dissolve and disperse the ultra-pure water, dripping a cross-linking agent, magnetically stirring in a constant-temperature water bath, performing cross-linking reaction to obtain a cross-linked hyperbranched polyamide-amine solution, and preserving heat for later use;

(2) Extracting the aramid fiber with absolute ethyl alcohol, washing, drying, immersing the aramid fiber into the cross-linked hyperbranched polyamide-amine solution obtained in the step (1), taking out and drying to obtain the cross-linked hyperbranched polyamide-amine modified meta-aramid fiber;

(3) Immersing the cross-linked hyperbranched polyamide-amine modified meta-aramid fiber obtained in the step (2) into silver ammonia solution, starting ultrasonic, performing silver ion ultrasonic adsorption, after the adsorption is completed, maintaining ultrasonic, dropwise adding glucose solution dropwise for ultrasonic reduction, standing, filtering, washing the filtrate with ultrapure water, and vacuum drying to obtain the cross-linked dendrimer silver-plated meta-aramid fiber.

2. The method of claim 1, wherein the aramid is one of an aramid fiber, an aramid nonwoven, or an aramid woven.

3. The process according to claim 1 or 2, characterized in that in step (1), the hyperbranched polyamide-amine has a number average molecular weight ranging from 500 to 1000 and a concentration ranging from 0.5 to 40g/L; the cross-linking agent is one of monoepoxy compound, dicycloxy compound, diglycidyl ester or polyepoxy compound, and the molar ratio of the cross-linking agent to hyperbranched polyamide-amine is (0.1-12) 1; the crosslinking reaction time is 0.5-12h; the water bath temperature is 10-100 ℃, and the magnetic stirring speed is 120-2400rpm.

4. A method according to claim 3, wherein the monoepoxy compound is epichlorohydrin, epibromohydrin or epoxypropionic acid; the bisoxy compound is diglycidyl ether, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, 1, 4-butanediol diglycidyl ether, poly (propylene glycol diglycidyl ether), bisphenol a diglycidyl ether, resorcinol diglycidyl ether or poly (dimethylsiloxane) diglycidyl ether; the diglycidyl esters are diglycidyl phthalate, diglycidyl adipate or diglycidyl aniline; the polyepoxy compound is glycerol triglycidyl ether or pentaerythritol triglycidyl ether.

5. The method according to claim 1 or 2, wherein in step (2), the soaking time is 0.5 to 6 hours.

6. The method according to claim 1 or 2, wherein in step (3), the ultrasonic frequency is 40KHz, the power is 120-360W, the ultrasonic adsorption time is 0.1-3h, and the ultrasonic reduction time is 0.5-4h; the vacuum drying temperature is 30-90 ℃ and the time is 6-24h.

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