Aramid paper and preparation method thereof

Abstract

The invention belongs to the technical field of papermaking, and relates to aramid paper and a preparation method thereof. According to the preparation method, aramid fibrid and ANF fiber are jointly used as raw materials, and the structural formula of ANF is as follows: # imgabs0 #, in the formula, n: m = (0.1-0.4): (0.6-0.9), m + n = 1, and-X is-F,-Cl,-Br or-I. The basis weight of the finally prepared aramid paper is 60 + / -1 g / m < 2 >, the thickness is 0.062-0.065 mm, the tensile strength is 4.58-5.5 kN / m, the tensile index is 48.1-51 N.m / g, the elongation at break is 7.88-8.9%, the electrical strength is 25-45 kV / mm, the effective diameter of an inhibition zone for staphylococcus aureus is 1.86-1.99 mm, the effective diameter of an inhibition zone for escherichia coli is 2.01-2.45 mm, and the effective diameter of an inhibition zone for candida albicans is 3.77-4.21 mm. The aramid paper has high insulativity and excellent mechanical property and antibacterial property, and the preparation method is simple and suitable for large-scale application.

Description

Technical Field

[0001] The invention belongs to the technical field of papermaking and relates to aramid paper and a preparation method thereof. Background Art

[0002] Aramid paper is made of short-cut fibers (aramid short-cut fibers) and pulp fibers (aramid precipitated fibers) in a certain ratio through a wet papermaking process. It has the characteristics of low density, high specific strength, high specific stiffness, impact resistance, corrosion resistance, self-extinguishing, good high-temperature stability and electromagnetic wave permeability. It is widely used in high-temperature insulation materials, aerospace and high-performance electronic equipment. In aramid paper, short-cut fibers are used as skeleton materials and are evenly dispersed in the paper, which determines the physical strength and mechanical properties of the paper. Pulp fibers are used as filling materials and bonding materials. They are partially melted during the hot pressing process, and the overall mechanical structure is formed by bonding the short-cut fibers and their own bonding, giving the paper overall strength and insulation properties.

[0003] However, the mechanical properties and insulation properties of the existing aramid paper need to be further improved, and the existing aramid paper does not have antibacterial properties, which limits its application in a wider range of fields, especially in situations where the material has high strength and high insulation requirements and good antibacterial properties, such as medical electronic equipment, food processing equipment, and high-end manufacturing fields that require a long-term sterile environment. In order to meet the demand for high-performance antibacterial materials in these fields, the research and development of aramid paper with enhanced mechanical properties, excellent insulation properties, and newly added antibacterial functions has become an important topic in the current field of materials science.

[0004] Reference 1 (Research on para-aramid paper reinforced with thermoplastic adhesive fibers [J]. Paper Science and Technology, 2013, 32(3), 33-38.) adds thermoplastic adhesive fibers to aramid paper. When the amount of thermoplastic adhesive fibers is 10%, the tensile index and tear index of the aramid paper are improved. However, on the one hand, this method requires the addition of components other than short-cut fibers and pulp fibers, and on the other hand, the aramid paper produced by this method does not have antibacterial properties.

[0005] Reference 2 (Reinforcement of Aramid 1414 Paper-based Composites by Modified Phenolic Resin [J]. Paper and Papermaking, 2012, 31(5): 33-37.) uses modified phenolic resin to reinforce aramid paper. Although this improves the mechanical properties of aramid paper, as mentioned above, on the one hand, this method requires the addition of components other than short-cut fibers and pulp fibers, and on the other hand, the aramid paper produced by this method does not have antibacterial properties. In addition, the addition of modified phenolic resin also reduces the insulation properties of aramid paper.

[0006] Therefore, it is necessary to develop a new aramid paper with excellent mechanical properties, insulation properties and antibacterial properties and a preparation method thereof. Summary of the invention

[0007] The purpose of the present invention is to solve the above problems existing in the prior art and to provide an aramid paper and a preparation method thereof.

[0008] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] A method for preparing aramid paper, using aramid fibrid and ANF fiber as raw materials, the structural formula of ANF is as follows:

[0010]

[0011] In the formula, n:m=0.1-0.4:0.6-0.9, and m+n=1, -X is -F, -Cl, -Br or -I.

[0012] As the preferred technical solution:

[0013] In the method for preparing aramid paper as described above, the mass ratio of aramid fibrid to ANF fiber is 1-2:3-4;

[0014] The water retention value of the aramid fibrid is 4.64-4.72 g / g, the average length of the aramid fibrid is 0.2-2 mm, the average diameter is 5-20 μm, and the aramid fibrid is para-aramid fibrid, meta-aramid fibrid or heterocyclic aramid fibrid;

[0015] The average length of ANF fiber is 2-8 mm, the linear density is 110-130 tex, the breaking strength is 31-38 cN / dtex, the tensile modulus is 990-1050 cN / dtex, the breaking elongation is 3.05-3.46%, the initial decomposition temperature is 510-550°C, the residual carbon rate at 800°C is 60-70%, the crystallinity is 50-52%, and the crystal axis orientation index is 0.941-0.955.

[0016] The method for preparing aramid paper as described above specifically comprises the following steps: preparing a mixed slurry of aramid fibrils, ANF fibers and water, pouring the mixed slurry into a paper former for mixing, drying (10 to 30 minutes) and hot rolling to obtain aramid paper.

[0017] In the method for preparing aramid paper as described above, the steps for preparing the mixed slurry are as follows:

[0018] (a) after mixing aramid fibrid with water, dispersing, beating and debonding are carried out in sequence to obtain slurry a; meanwhile, after mixing ANF fiber with water, debonding is carried out to obtain slurry b;

[0019] (b) Slurry a and slurry b are mixed and then dispersed to obtain a mixed slurry.

[0020] In the method for preparing aramid paper as described above, in step (a), the beating degree of slurry a is 65-70°SR, the concentration of slurry a is 0.7-1.0wt%, and the concentration of slurry b is 1.4-2.5wt%;

[0021] When preparing slurry a, dispersion and beating are carried out in a trough beater, the knife load is 0 kg during dispersion, the dispersion time is 1 to 2 minutes, the knife load is 5 to 10 kg during beating, the beating time is 30 to 120 minutes, and defibrination is carried out in a fiber disintegrator, and the defibrination speed is 60,000 to 80,000 r.

[0022] When preparing slurry b, the defiberization is carried out in a fiber disintegrator, and the defiberization speed is 6000-10000r;

[0023] In step (b), the defiberization is carried out in a fiber disintegrator at a defiberization speed of 1000 to 2000 r.

[0024] In the method for preparing aramid paper as described above, the preparation process of the mixed slurry is: after mixing aramid fibrid, ANF fiber and water, the mixed slurry is dispersed, beaten and decomposed in sequence to obtain the mixed slurry.

[0025] In the preparation method of aramid paper as described above, dispersion and beating are carried out in a trough beater, the knife load during dispersion is 0 kg, the dispersion time is 3 to 5 minutes, the knife load during beating is 12 to 16 kg, the beating time is 150 to 180 minutes, and defibrination is carried out in a fiber disintegrator, and the defibrination rotation number is 10,000 to 11,000 r.

[0026] In the preparation method of aramid paper as described above, during hot rolling forming, the hot pressing temperature is 260-300°C, the hot pressing pressure is 10-16MPa, the number of hot pressing times is 1-5 times, and the hot pressing time is 10-60s.

[0027] In the above-mentioned method for preparing aramid paper, the preparation steps of ANF fiber are as follows:

[0028] (i) Synthesis of XNB monomers;

[0029] Under the action of concentrated sulfuric acid, diphenylacetylene is reacted with nitric acid to generate p-nitrophenylacetylene, and then under the action of palladium carbon (Pd / C), p-nitrophenylacetylene is reduced with hydrogen to generate p-aminophenylacetylene, and then p-aminophenylacetylene is reacted with X2 (F2, Cl2, Br2 or I2) to generate XNB monomer;

[0030] The structural formula of XNB monomer is as follows:

[0031]

[0032] Wherein, -X is -F, -Cl, -Br or -I;

[0033] (ii) preparing ANF solution;

[0034] Under the protection of inert gas or nitrogen, DMAc (N, N-dimethylacetamide) and LiCl (lithium chloride) are first added to the reactor, stirring is started, and then p-phenylenediamine and XNB monomer are added. After being completely dissolved, the temperature is lowered to -4 to 0°C, and then the temperature of the reaction system is adjusted to 25 to 30°C, and terephthaloyl chloride is added in batches. After the addition is completed, the reaction is continued for 20 to 40 minutes, and finally LiOH (lithium hydroxide) is added for neutralization to obtain ANF solution;

[0035] The molar ratio of p-phenylenediamine, XNB monomer, terephthaloyl chloride, DMAc, LiCl and LiOH is 1:1-1.2:3.1-3.5:100-1000:1-5:2-4;

[0036] (iii) spinning;

[0037] The ANF solution is centrifuged to remove salt and then placed in a reaction tank for degassing, followed by spinning, stretching, washing, drying, dry heat stretching, oiling, heat setting, and winding to obtain ANF fibers;

[0038] The number of spinneret holes on the spinneret plate is 100 to 500, and the diameter of the spinneret holes is 0.08 mm;

[0039] The spinning process parameters include: spinning solution temperature 20°C; metering pump speed 4-7r / min; spinneret speed 7-12m / min; air bath height 10-15mm; coagulation bath (DMAc aqueous solution with a volume concentration of 30-60%) temperature 25-35°C; water washing temperature 70-90°C; dry heat stretching temperature 300-320°C; heat setting temperature 290-350°C; heat setting time 60-120s.

[0040] The present invention also provides an aramid paper, which is prepared by the method for preparing aramid paper as described in any one of the above items; the basis weight of the aramid paper is 60±1g / m 2 The thickness is 0.062-0.065mm, the tensile strength is 4.58-5.5kN / m, the tensile index is 48.1-51N·m / g, the elongation at break is 7.88-8.9%, the electrical strength is 25-45kV / mm, the effective diameter of the inhibition zone for Staphylococcus aureus is 1.86-1.99mm, the effective diameter of the inhibition zone for Escherichia coli is 2.01-2.45mm, and the effective diameter of the inhibition zone for Candida albicans is 3.77-4.21mm.

[0041] The aramid paper of the present invention has excellent insulation performance, and the principle is as follows:

[0042] After beating, the membrane structure of aramid fibrids is gradually destroyed, and the specific surface area is increased. After the introduction of ANF fibers, on the one hand, the X atoms on the surface of ANF fibers can fill the gaps between aramid fibrids and ANF fibers, and on the other hand, the X atoms on the surface of ANF fibers can form hydrogen bonds with the H atoms of the amide bonds of aramid fibrids. The hydrogen bonds have orientation and can fix the aramid fibrids, reduce their entanglement and curling, and expose more binding sites of aramid fibrids with ANF fibers, reducing the gaps between aramid fibrids and ANF fibers. This dual effect makes the sealing adhesion between aramid fibrids and ANF fibers high, and thus makes the insulation performance of aramid paper excellent.

[0043] The aramid paper of the present invention has excellent mechanical properties, and the principle is as follows:

[0044] ① By introducing the structural groups of ANF fibers, the surface hydrophobicity and molecular weight are improved. These changes strengthen the interaction between molecules, which is beneficial to the improvement of the uniformity of the paper. The improvement of uniformity promotes the stability of the membrane structure of aramid fibrils, so that the interface bonding between fibers is improved, and finally the overall bonding force of the paper is strengthened, and the mechanical properties are also improved;

[0045] ② After the introduction of ANF fiber into the system, on the one hand, the surface of ANF fiber is rich in -X groups, which is equivalent to the presence of a thin lubricating film on the surface. ANF fiber can act as a lubricant, so that the aramid fibrils can easily slide past each other without entanglement when they come into contact with each other. On the other hand, the viscosity of the system will be significantly increased, which will greatly limit the freedom of movement of the aramid fibrils in the system, effectively avoid direct contact between the aramid fibrils, reduce the flocculation phenomenon between the aramid fibrils, and thus improve the ability of the aramid fibrils to form and interweave. In addition, the higher viscosity will also make many aramid fibrils relax and become passive before they come into contact with each other when the stirring is stopped, and finally form a stable fiber network in the suspension of the mixed slurry. At the same time, this process also reduces the internal stress between the aramid fibrils.

[0046] The aramid paper of the present invention has excellent antibacterial properties, and the principle is as follows:

[0047] On the one hand, when the -X group on the surface of ANF fiber comes into direct contact with bacteria, the X atom will insert into and pierce the bacterial cell membrane, causing mechanical damage to the cell membrane, leading to leakage of intracellular substances, and exerting significant cell membrane pressure on the bacteria, thus killing the bacteria. On the other hand, when aramid paper comes into contact with the bacterial cell membrane, the CX covalent bond on the surface of ANF fiber can be hydrolyzed in a water environment, resulting in charge transfer or reactive oxygen species, causing oxidative stress. The released halogens directly react with important bacterial cell components that affect metabolism and viability, disrupting the bacterial metabolic process and killing the bacteria. These two aspects work synergistically to achieve an excellent antibacterial effect.

[0048] Beneficial effects:

[0049] (1) The fibers of the aramid paper provided by the present invention are regularly interwoven and arranged, and have a high paper evenness.

[0050] (2) The aramid paper provided by the present invention has improved electrical strength and high insulation properties.

[0051] (3) The aramid paper of the present invention has improved tensile strength and tensile index and has good mechanical properties.

[0052] (4) The aramid paper of the present invention can inhibit Staphylococcus aureus, Escherichia coli and Candida albicans and has excellent antibacterial properties.

[0053] (5) The preparation method of the present invention has simple steps and is suitable for large-scale industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 It is the synthetic route diagram of XNB monomer;

[0055] Figure 2 It is a single XNB 1 HNMR test spectrum (X is F);

[0056] Figure 3 It is a single XNB 13 CNMR test spectrum (X is F);

[0057] Figure 4 It is a single XNB 1 HNMR test spectrum (X is Cl);

[0058] Figure 5 It is a single XNB 13 CNMR test spectrum (X is Cl);

[0059] Figure 6 It is a single XNB 1 HNMR test spectrum (X is Br);

[0060] Figure 7 It is a single XNB 13 CNMR test spectrum (X is Br);

[0061] Figure 8 It is a single XNB 1 HNMR test spectrum (X is I);

[0062] Fig. 9 It is a single XNB 13 CNMR test spectrum (X is I);

[0063] Fig.10 It is the synthesis pathway diagram of ANF (X is F). DETAILED DESCRIPTION

[0064] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0065] The following are the test methods for the relevant performance indicators in each embodiment:

[0066] (1) Water retention value of aramid fibrils: The test was conducted in accordance with GB / T 29286-2012 “Determination of water retention value of pulp”.

[0067] (2) Linear density, breaking strength, tensile modulus and elongation at break of ANF fibers: The tests were conducted using an electronic universal testing machine in accordance with GB / T 19975-2005. The test conditions were a gauge length of 500 mm and a tensile rate of 250 mm / min.

[0068] (3) Initial decomposition temperature of ANF fiber and residual carbon rate at 800°C: ANF fiber was made into powder and tested using TG 209 thermogravimetric analyzer. The test conditions were temperature 35-800°C, heating rate 10°C / min, nitrogen atmosphere, and the thermogravimetric (TG) curve of the sample was obtained to obtain the initial decomposition temperature of ANF fiber and the residual carbon rate at 800°C.

[0069] (4) Crystallinity and crystal axis orientation index of ANF fibers: ANF fibers were made into powder and tested using an X-ray diffraction spectrometer. The test conditions were Cu Kα target (wavelength of 0.15406 nm), tube voltage of 20-60 kV, tube current of 20-60 mA, scanning frequency of 12° / min, and scanning angle (2θ) of 5°-90°. The wide-angle X-ray diffraction spectrum (WAXD) and two-dimensional wide-angle X-ray diffraction spectrum (2D-WXRD) of ANF were obtained. The crystallinity of the fibers was calculated by peak fitting of the WAXD spectrum. The crystal axis orientation index (R) was calculated from the 2D-WXRD spectrum using the crystal axis orientation index analysis method. The specific calculation method is as follows: select the sharpest diffraction spot on the 2D-WXRD spectrum, select the X-ray azimuth angle of -90° to 90° for scanning integration along the concentric arc direction, and obtain the distribution curve of the diffraction intensity in the azimuth; according to the half-peak width (H) of the curve, calculate the crystal axis orientation index (R), the calculation formula R = (180°-H) / 180°, and obtain the crystallinity and crystal axis orientation index of the ANF fiber.

[0070] (5) Beating degree of aramid fibrid: The test was conducted in accordance with GB / T 3332-2004 “Determination of the beating degree of pulp (Schober-Riegle method)”.

[0071] (6) Tensile strength, tensile index and elongation at break of aramid paper: tested in accordance with GB / T 20629.2-2013 “Non-cellulose paper for electrical purposes Part 2: Test methods”.

[0072] (7) Electrical strength of aramid paper: Tested in accordance with GB / T 1408.1-2016 “Electrical strength test methods for insulating materials - Part 1: Tests at power frequency”.

[0073] (8) Antibacterial properties of aramid paper: The test was conducted in accordance with GB / T 20944.1-2007 “Evaluation of antibacterial properties of textiles Part 1: Agar plate diffusion method”.

[0074] Example 1

[0075] A method for preparing ANF fiber, the specific steps are as follows:

[0076] (i) Synthesis of XNB monomers;

[0077] The synthetic route of XNB monomer is as follows Figure 1 As shown, diphenylacetylene is reacted with nitric acid under the action of concentrated sulfuric acid (concentration 85wt%, solvent is deionized water) to generate p-nitrodiphenylacetylene, and then p-nitrodiphenylacetylene is reduced with hydrogen under the action of palladium carbon (palladium content is 0.5wt%) to generate p-aminodiphenylacetylene, and then p-aminodiphenylacetylene is reacted with F2 to generate XNB monomer; XNB monomer1 HNMR test spectrum Figure 2 As shown, XNB monomer 13 CNMR test spectrum Figure 3 As shown;

[0078] The structural formula of XNB monomer is as follows:

[0079]

[0080] Wherein, -X is -F;

[0081] (ii) preparing ANF solution;

[0082] The synthetic route of ANF is as follows Fig.10 As shown, under the protection of nitrogen, DMAc and LiCl were first added to the reactor, stirring was started, and then p-phenylenediamine and XNB monomers were added. After they were completely dissolved, the temperature was lowered to -4°C, and then the temperature of the reaction system was adjusted to 25°C. Terephthaloyl chloride was added in batches. After the addition was completed, the reaction was continued for 20 minutes, and finally LiOH was added for neutralization to obtain ANF solution.

[0083] The molar ratio of p-phenylenediamine, XNB monomer, terephthaloyl chloride, DMAc, LiCl, and LiOH is 1:1:3.1:100:1:2;

[0084] The structural formula of ANF is as follows:

[0085]

[0086] Wherein, n:m=0.1:0.9, and m+n=1, -X is -F;

[0087] (iii) spinning;

[0088] The ANF solution is centrifuged to remove salt and then placed in a reaction tank for degassing, followed by spinning, stretching, washing, drying, dry heat stretching, oiling, heat setting, and winding to obtain ANF fibers;

[0089] The number of spinneret holes on the spinneret plate is 100, and the diameter of the spinneret holes is 0.08 mm;

[0090] Spinning process parameters: spinning solution temperature 20℃; metering pump speed 4r / min; spinneret speed 7m / min; air bath height 10mm; coagulation bath (DMAc aqueous solution with a volume concentration of 30%) temperature 25℃; water washing temperature 70℃; dry heat stretching temperature 300℃; heat setting temperature 290℃; heat setting time 60s.

[0091] The final ANF fiber has a linear density of 110tex, a breaking strength of 31cN / dtex, a tensile modulus of 990cN / dtex, an elongation at break of 3.05%, an initial decomposition temperature of 510°C, a carbon residue rate of 60% at 800°C, a crystallinity of 50%, and a crystal axis orientation index of 0.941.

[0092] Example 2

[0093] A method for preparing ANF fiber, the specific steps are as follows:

[0094] (i) Synthesis of XNB monomers;

[0095] The synthetic route of XNB monomer is as follows Figure 1 As shown, diphenylacetylene is reacted with nitric acid under the action of concentrated sulfuric acid (concentration is 92wt%, solvent is deionized water) to generate p-nitrodiphenylacetylene, and then p-nitrodiphenylacetylene is reduced with hydrogen under the action of palladium carbon (palladium content is 5wt%) to generate p-aminodiphenylacetylene, and then p-aminodiphenylacetylene is reacted with Cl2 to generate XNB monomer; XNB monomer 1 HNMR test spectrum Figure 4 As shown, XNB monomer 13 CNMR test spectrum Figure 5 As shown;

[0096] The structural formula of XNB monomer is as follows:

[0097]

[0098] Wherein, -X is -Cl;

[0099] (ii) preparing ANF solution;

[0100] Under the protection of nitrogen, DMAc and LiCl were first added to the reactor, and stirring was started. Then, p-phenylenediamine and XNB monomers were added. After they were completely dissolved, the temperature was lowered to -2°C. Then, the temperature of the reaction system was adjusted to 27°C, and terephthaloyl chloride was added in batches. After the addition was completed, the reaction was continued for 30 minutes. Finally, LiOH was added for neutralization to obtain ANF solution.

[0101] The molar ratio of p-phenylenediamine, XNB monomer, terephthaloyl chloride, DMAc, LiCl, and LiOH is 1:1.1:3.4:500:3:3;

[0102] The structural formula of ANF is as follows:

[0103]

[0104] Wherein, n:m=0.2:0.8, and m+n=1, -X is -Cl;

[0105] (iii) spinning;

[0106] The ANF solution is centrifuged to remove salt and then placed in a reaction tank for degassing, followed by spinning, stretching, washing, drying, dry heat stretching, oiling, heat setting, and winding to obtain ANF fibers;

[0107] The number of spinneret holes on the spinneret plate is 200, and the diameter of the spinneret holes is 0.08 mm;

[0108] Spinning process parameters: spinning solution temperature 20℃; metering pump speed 5r / min; spinneret speed 9m / min; air bath height 12mm; coagulation bath (DMAc aqueous solution with a volume concentration of 45%) temperature 30℃; water washing temperature 75℃; dry heat stretching temperature 310℃; heat setting temperature 320℃; heat setting time 75s.

[0109] The final ANF fiber has a linear density of 116tex, a breaking strength of 34cN / dtex, a tensile modulus of 1020cN / dtex, an elongation at break of 3.25%, an initial decomposition temperature of 530°C, a carbon residue rate of 63% at 800°C, a crystallinity of 51%, and a crystal axis orientation index of 0.945.

[0110] Example 3

[0111] A method for preparing ANF fiber, the specific steps are as follows:

[0112] (i) Synthesis of XNB monomers;

[0113] The synthetic route of XNB monomer is as follows Figure 1 As shown, diphenylacetylene is reacted with nitric acid under the action of concentrated sulfuric acid (concentration is 88wt%, solvent is deionized water) to generate p-nitrodiphenylacetylene, and then p-nitrodiphenylacetylene is reduced with hydrogen under the action of palladium carbon (palladium content is 8wt%) to generate p-aminodiphenylacetylene, and then p-aminodiphenylacetylene is reacted with Br2 to generate XNB monomer; the XNB monomer 1 HNMR test spectrum Figure 6 As shown, XNB monomer 13 CNMR test spectrum Figure 7 As shown;

[0114] The structural formula of XNB monomer is as follows:

[0115]

[0116] Wherein, -X is -Br;

[0117] (ii) preparing ANF solution;

[0118] Under the protection of argon, DMAc and LiCl were first added to the reactor, and stirring was started. Then, p-phenylenediamine and XNB monomers were added. After they were completely dissolved, the temperature was lowered to -1°C. Then, the temperature of the reaction system was adjusted to 28°C, and terephthaloyl chloride was added in batches. After the addition was completed, the reaction was continued for 35 minutes. Finally, LiOH was added for neutralization to obtain ANF solution.

[0119] The molar ratio of p-phenylenediamine, XNB monomer, terephthaloyl chloride, DMAc, LiCl, and LiOH is 1:1.2:3.3:700:2:4;

[0120] The structural formula of ANF is as follows:

[0121]

[0122] Wherein, n:m=0.3:0.7, and m+n=1, -X is -Br;

[0123] (iii) spinning;

[0124] The ANF solution is centrifuged to remove salt and then placed in a reaction tank for degassing, followed by spinning, stretching, washing, drying, dry heat stretching, oiling, heat setting, and winding to obtain ANF fibers;

[0125] The number of spinneret holes on the spinneret plate is 300, and the diameter of the spinneret holes is 0.08 mm;

[0126] Spinning process parameters: spinning solution temperature 20℃; metering pump speed 6r / min; spinneret speed 10m / min; air bath height 13mm; coagulation bath (50% DMAc aqueous solution by volume concentration) temperature 32℃; water washing temperature 80℃; dry heat stretching temperature 315℃; heat setting temperature 340℃; heat setting time 90s.

[0127] The final ANF fiber has a linear density of 120tex, a breaking strength of 36cN / dtex, a tensile modulus of 1035cN / dtex, an elongation at break of 3.34%, an initial decomposition temperature of 540°C, a carbon residue rate of 65% at 800°C, a crystallinity of 51.4%, and a crystal axis orientation index of 0.948.

[0128] Example 4

[0129] A method for preparing ANF fiber, the specific steps are as follows:

[0130] (i) Synthesis of XNB monomers;

[0131] The synthetic route of XNB monomer is as follows Figure 1As shown, diphenylacetylene is reacted with nitric acid under the action of concentrated sulfuric acid (concentration is 98wt%, the solvent is deionized water) to generate p-nitrodiphenylacetylene, and then p-nitrodiphenylacetylene is reduced with hydrogen under the action of palladium carbon (palladium content is 15wt%) to generate p-aminodiphenylacetylene, and then p-aminodiphenylacetylene is reacted with I2 to generate XNB monomer; the XNB monomer 1 HNMR test spectrum Figure 8 As shown, XNB monomer 13 CNMR test spectrum Fig. 9 As shown;

[0132] The structural formula of XNB monomer is as follows:

[0133]

[0134] Wherein, -X is -I;

[0135] (ii) preparing ANF solution;

[0136] Under the protection of nitrogen, DMAc and LiCl were first added to the reactor, and stirring was started. Then, p-phenylenediamine and XNB monomers were added. After they were completely dissolved, the temperature was lowered to 0°C. Then, the temperature of the reaction system was adjusted to 30°C, and terephthaloyl chloride was added in batches. After the addition was completed, the reaction was continued for 40 minutes. Finally, LiOH was added for neutralization to obtain ANF solution.

[0137] The molar ratio of p-phenylenediamine, XNB monomer, terephthaloyl chloride, DMAc, LiCl, and LiOH is 1:1.2:3.5:1000:5:4;

[0138] The structural formula of ANF is as follows:

[0139]

[0140] Wherein, n:m=0.4:0.6, and m+n=1, -X is -I;

[0141] (iii) spinning;

[0142] The ANF solution is centrifuged to remove salt and then placed in a reaction tank for degassing, followed by spinning, stretching, washing, drying, dry heat stretching, oiling, heat setting, and winding to obtain ANF fibers;

[0143] The number of spinneret holes on the spinneret plate is 500, and the diameter of the spinneret holes is 0.08 mm;

[0144] Spinning process parameters: spinning solution temperature 20℃; metering pump speed 7r / min; spinneret speed 12m / min; air bath height 15mm; coagulation bath (DMAc aqueous solution with a volume concentration of 60%) temperature 35℃; water washing temperature 90℃; dry heat stretching temperature 320℃; heat setting temperature 350℃; heat setting time 120s.

[0145] The final ANF fiber has a linear density of 130tex, a breaking strength of 38cN / dtex, a tensile modulus of 1050cN / dtex, an elongation at break of 3.46%, an initial decomposition temperature of 550°C, a residual carbon rate of 70% at 800°C, a crystallinity of 52%, and a crystal axis orientation index of 0.955.

[0146] Example 5

[0147] A method for preparing aramid paper, the specific steps are as follows:

[0148] (1) Preparation of raw materials;

[0149] Aramid fiber: water retention value is 4.65g / g, average length is 0.2mm, average diameter is 5μm, and the aramid fiber is meta-aramid fiber;

[0150] ANF ​​fiber: obtained by cutting the ANF fiber of Example 1, with an average length of 2 mm;

[0151] (2) Preparation of mixed slurry;

[0152] Aramid fibrids, ANF fibers and water are prepared into a mixed slurry, wherein the mass ratio of aramid fibrids to ANF fibers is 1:4, and the mass ratio of aramid fibrids to water is 1:100;

[0153] The preparation process of the mixed slurry is as follows: after mixing aramid fibrils, ANF fibers and water, the mixed slurry is dispersed, beaten and deflaked in sequence to obtain the mixed slurry; the dispersion and beating are carried out in a trough-type beating machine, the knife load is 0 kg during the dispersion, the dispersion time is 3 min, the knife load is 12 kg during the beating, the beating time is 150 min, and the deflaking is carried out in a fiber disintegrator, and the deflaking speed is 10000 r;

[0154] (3) Hot rolling forming;

[0155] The mixed slurry was poured into a paper former for mixing, drying for 10 minutes, and hot rolling to obtain aramid paper. During hot rolling, the hot pressing temperature was 260°C, the hot pressing pressure was 10 MPa, the hot pressing number was 1, and the hot pressing time was 10 seconds.

[0156] The final aramid paper has a basis weight of 59 g / m 2, thickness is 0.062mm, tensile strength is 4.58kN / m, tensile index is 48.1N·m / g, elongation at break is 7.88%, electrical strength is 25kV / mm, the effective diameter of the inhibition zone for Staphylococcus aureus is 1.99mm, the effective diameter of the inhibition zone for Escherichia coli is 2.45mm, and the effective diameter of the inhibition zone for Candida albicans is 4.21mm.

[0157] Comparative Example 1

[0158] A method for preparing aramid paper is basically the same as that of Example 5, except that the ANF fibers are replaced with para-aramid chopped fibers of equal mass.

[0159] The final aramid paper has a tensile strength of 4.23 kN / m, a tensile index of 46 N·m / g, an elongation at break of 7.51%, an electrical strength of 23 kV / mm, an effective diameter of the inhibition zone for Staphylococcus aureus of 0 mm, an effective diameter of the inhibition zone for Escherichia coli of 0 mm, and an effective diameter of the inhibition zone for Candida albicans of 0 mm.

[0160] By comparing Example 1 with Comparative Example 5, it can be seen that after the ANF fiber is replaced, the tensile strength, tensile index, elongation at break, electrical strength, etc. of the aramid paper are reduced, and the inhibition zone against Staphylococcus aureus, Escherichia coli, and Candida albicans is also reduced. This is because compared with the para-aramid chopped fiber, the ANF fiber is better combined with the aramid precipitated fiber, and the prepared aramid paper has better performance.

[0161] Example 6

[0162] A method for preparing aramid paper, the specific steps are as follows:

[0163] (1) Preparation of raw materials;

[0164] Aramid fiber: water retention value is 4.72g / g, average length is 2mm, average diameter is 20μm, and the aramid fiber is para-aramid fiber;

[0165] ANF ​​fiber: obtained by cutting the ANF fiber of Example 2, with an average length of 5 mm;

[0166] (2) Preparation of mixed slurry;

[0167] Aramid fibrids, ANF fibers and water are prepared into a mixed slurry, wherein the mass ratio of aramid fibrids to ANF fibers is 2:3, and the mass ratio of aramid fibrids to water is 1:150;

[0168] The preparation process of the mixed slurry is as follows: after mixing aramid fibrils, ANF fibers and water, the mixed slurry is dispersed, beaten and deflaked in sequence to obtain the mixed slurry; the dispersion and beating are carried out in a trough-type beating machine, the knife load is 0 kg during the dispersion, the dispersion time is 5 min, the knife load is 16 kg during the beating, the beating time is 180 min, and the deflaking is carried out in a fiber disintegrator, and the deflaking speed is 11000 r;

[0169] (3) Hot rolling forming;

[0170] The mixed slurry was poured into a paper former for mixing, drying for 15 minutes, and hot rolling to obtain aramid paper. During hot rolling, the hot pressing temperature was 290°C, the hot pressing pressure was 15 MPa, the hot pressing times were 4 times, and the hot pressing time was 50 seconds.

[0171] The final aramid paper has a basis weight of 60.5 g / m 2 , thickness is 0.065mm, tensile strength is 5.14kN / m, tensile index is 49.8N·m / g, elongation at break is 8.56%, electrical strength is 40kV / mm, the effective diameter of the inhibition zone for Staphylococcus aureus is 1.9mm, the effective diameter of the inhibition zone for Escherichia coli is 2.34mm, and the effective diameter of the inhibition zone for Candida albicans is 3.97mm.

[0172] Example 7

[0173] A method for preparing aramid paper, the specific steps are as follows:

[0174] (1) Preparation of raw materials;

[0175] Aramid fiber: water retention value is 4.64g / g, average length is 0.4mm, average diameter is 8μm, and the aramid fiber is meta-aramid fiber;

[0176] ANF ​​fiber: obtained by cutting the ANF fiber of Example 3, with an average length of 8 mm;

[0177] (2) Preparation of mixed slurry;

[0178] Aramid fibrids, ANF fibers and water are prepared into a mixed slurry, wherein the mass ratio of aramid fibrids to ANF fibers is 1:3.5;

[0179] The preparation process of the mixed slurry is as follows:

[0180] (a) After mixing aramid fiber with water, the aramid fiber is dispersed, beaten and deflaked in sequence to obtain slurry a. Meanwhile, after mixing ANF fiber with water, the aramid fiber is deflaked to obtain slurry b. When preparing slurry a, the dispersion and beating are carried out in a trough beater, the knife load is 0 kg during the dispersion, the dispersion time is 1 min, the knife load is 5 kg during the beating, the beating time is 30 min, the deflaking is carried out in a fiber disintegrator, and the deflaking speed is 60000 r. When preparing slurry b, the deflaking is carried out in a fiber disintegrator, and the deflaking speed is 6000 r. The beating degree of slurry a is 65° SR, the concentration of slurry a is 0.7 wt%, and the concentration of slurry b is 1.4 wt%;

[0181] (b) mixing slurry a and slurry b, and then defibrinating the slurry in a fiber disintegrator at a defibrination speed of 1000 r to obtain a mixed slurry;

[0182] (3) Hot rolling forming;

[0183] The mixed slurry was poured into a paper former for mixing, drying for 20 minutes, and hot rolling to obtain aramid paper. During hot rolling, the hot pressing temperature was 280°C, the hot pressing pressure was 12 MPa, the hot pressing times were 2 times, and the hot pressing time was 20 seconds.

[0184] The final aramid paper has a basis weight of 59.5 g / m 2 , thickness is 0.063mm, tensile strength is 4.66kN / m, tensile index is 48.5N·m / g, elongation at break is 7.99%, electrical strength is 30kV / mm, the effective diameter of the inhibition zone for Staphylococcus aureus is 1.86mm, the effective diameter of the inhibition zone for Escherichia coli is 2.01mm, and the effective diameter of the inhibition zone for Candida albicans is 3.77mm.

[0185] Comparative Example 2

[0186] A method for preparing aramid paper is basically the same as Example 7, except that the ANF fibers are replaced with para-aramid chopped fibers of equal mass.

[0187] The final aramid paper has a tensile strength of 4.65 kN / m, a tensile index of 48.1 N·m / g, an elongation at break of 7.88%, an electrical strength of 29 kV / mm, an effective diameter of the inhibition zone for Staphylococcus aureus of 0 mm, an effective diameter of the inhibition zone for Escherichia coli of 0 mm, and an effective diameter of the inhibition zone for Candida albicans of 0 mm.

[0188] By comparing Example 7 with Comparative Example 2, it can be seen that the tensile strength, tensile index, elongation at break, electrical strength, etc. of the aramid paper are all reduced, and the inhibition zones against Staphylococcus aureus, Escherichia coli, and Candida albicans are also reduced. This is because compared with para-aramid chopped fibers, ANF fibers are better combined with aramid precipitated fibers, and the prepared aramid paper has better performance.

[0189] Example 8

[0190] A method for preparing aramid paper, the specific steps are as follows:

[0191] (1) Preparation of raw materials;

[0192] Aramid fiber: water retention value is 4.68g / g, average length is 1.1mm, average diameter is 12μm, and the aramid fiber is a hybrid aramid fiber;

[0193] ANF ​​fiber: obtained by cutting the ANF fiber of Example 4, with an average length of 3 mm;

[0194] (2) Preparation of mixed slurry;

[0195] Aramid fibrids, ANF fibers and water are prepared into a mixed slurry, wherein the mass ratio of aramid fibrids to ANF fibers is 1:3;

[0196] The preparation process of the mixed slurry is as follows:

[0197] (a) After mixing aramid fiber with water, the aramid fiber is dispersed, beaten and deflaked in sequence to obtain slurry a. Meanwhile, after mixing ANF fiber with water, the aramid fiber is deflaked to obtain slurry b. When preparing slurry a, the dispersion and beating are carried out in a trough beater. During the dispersion, the knife load is 0 kg and the dispersion time is 1.5 min. During the beating, the knife load is 7.5 kg and the beating time is 75 min. The deflaking is carried out in a fiber disintegrator at a deflaking speed of 70000 r. When preparing slurry b, the deflaking is carried out in a fiber disintegrator at a deflaking speed of 8000 r. The beating degree of slurry a is 67° SR, the concentration of slurry a is 0.85 wt%, and the concentration of slurry b is 1.9 wt%.

[0198] (b) mixing slurry a and slurry b, and then defibrinating the slurry in a fiber disintegrator at a defibrination speed of 1500 r to obtain a mixed slurry;

[0199] (3) Hot rolling forming;

[0200] The mixed slurry was poured into a paper former for mixing, drying for 25 minutes, and hot rolling to obtain aramid paper. During hot rolling, the hot pressing temperature was 270°C, the hot pressing pressure was 14 MPa, the hot pressing times were 3 times, and the hot pressing time was 35 seconds.

[0201] The final aramid paper has a basis weight of 60 g / m 2 , thickness is 0.064mm, tensile strength is 4.90kN / m, tensile index is 49.2N·m / g, elongation at break is 8.33%, electrical strength is 35kV / mm, the effective diameter of the inhibition zone for Staphylococcus aureus is 1.9mm, the effective diameter of the inhibition zone for Escherichia coli is 2.3mm, and the effective diameter of the inhibition zone for Candida albicans is 3.97mm.

[0202] Example 9

[0203] A method for preparing aramid paper, the specific steps are as follows:

[0204] (1) Preparation of raw materials;

[0205] Aramid fiber: water retention value is 4.71g / g, average length is 1.7mm, average diameter is 17μm, and the aramid fiber is para-aramid fiber;

[0206] ANF ​​fiber: obtained by cutting the ANF fiber of Example 1, with an average length of 6 mm;

[0207] (2) Preparation of mixed slurry;

[0208] Aramid fibrids, ANF fibers and water are prepared into a mixed slurry, wherein the mass ratio of aramid fibrids to ANF fibers is 2:3;

[0209] The preparation process of the mixed slurry is as follows:

[0210] (a) After mixing aramid fiber with water, the aramid fiber is dispersed, beaten and deflaked in sequence to obtain slurry a. Meanwhile, after mixing ANF fiber with water, the aramid fiber is deflaked to obtain slurry b. When preparing slurry a, the dispersion and beating are carried out in a trough beater. During the dispersion, the knife load is 0 kg and the dispersion time is 2 min. During the beating, the knife load is 10 kg and the beating time is 120 min. The deflaking is carried out in a fiber disintegrator at a deflaking speed of 80000 r. When preparing slurry b, the deflaking is carried out in a fiber disintegrator at a deflaking speed of 10000 r. The beating degree of slurry a is 70° SR, the concentration of slurry a is 1.0 wt%, and the concentration of slurry b is 2.5 wt%.

[0211] (b) mixing slurry a and slurry b, and then defibrinating the slurry in a fiber disintegrator at a defibrination speed of 2000 r to obtain a mixed slurry;

[0212] (3) Hot rolling forming;

[0213] The mixed slurry was poured into a paper former for mixing, drying for 30 minutes, and hot rolling to obtain aramid paper. During hot rolling, the hot pressing temperature was 300°C, the hot pressing pressure was 16 MPa, the hot pressing times were 5 times, and the hot pressing time was 60 seconds.

[0214] The final aramid paper has a basis weight of 61 g / m 2 , thickness is 0.065mm, tensile strength is 5.22kN / m, tensile index is 50.3N·m / g, elongation at break is 8.85%, electrical strength is 44kV / mm, the effective diameter of the inhibition zone for Staphylococcus aureus is 1.95mm, the effective diameter of the inhibition zone for Escherichia coli is 2.33mm, and the effective diameter of the inhibition zone for Candida albicans is 4mm.

[0215] Example 10

[0216] A method for preparing aramid paper is basically the same as that of Example 9, except that the aramid fibrids are heterocyclic aramid (Armos fiber, aramid F-12) fibrids.

[0217] The final aramid paper has a tensile strength of 5.5 kN / m, a tensile index of 51 N·m / g, an elongation at break of 8.9%, an electrical strength of 45 kV / mm, an effective diameter of the inhibition zone for Staphylococcus aureus of 1.98 mm, an effective diameter of the inhibition zone for Escherichia coli of 2.35 mm, and an effective diameter of the inhibition zone for Candida albicans of 4.1 mm.

[0218] Embodiment 11

[0219] A method for preparing aramid paper is basically the same as Example 9, except that: the preparation process of the mixed slurry is: after mixing aramid precipitated fibers, ANF fibers and water, they are dispersed, pulped and deflaked in sequence to obtain a mixed slurry; the dispersion and beating are carried out in a trough beater, the knife load during dispersion is 0 kg, and the dispersion time is 2 min, the knife load during pulping is 10 kg, and the pulping time is 120 min, and the deflaking is carried out in a fiber separator, and the deflaking speed is 82000 r.

[0220] The final aramid paper has a tensile strength of 5.1 kN / m, a tensile index of 50 N·m / g, an elongation at break of 8.7%, an electrical strength of 43.5 kV / mm, an effective diameter of the inhibition zone for Staphylococcus aureus of 1.94 mm, an effective diameter of the inhibition zone for Escherichia coli of 2.25 mm, and an effective diameter of the inhibition zone for Candida albicans of 3.88 mm.

[0221] By comparing Example 11 with Example 9, it can be seen that the tensile strength, tensile index, elongation at break, electrical strength, etc. of the aramid paper of Example 11 are reduced relative to those of Example 9, and the inhibition zone against Staphylococcus aureus, Escherichia coli, and Candida albicans is also reduced. This is because the debonding and dispersion effects of Example 11 are not good.

Claims

1. A method for preparing aramid paper, characterized in that: Aramid fiber and ANF fiber are used as raw materials. The structural formula of ANF is as follows: In the formula, n:m=0.1-0.4:0.6-0.9, and m+n=1, -X is -F, -Cl, -Br or -I.

2. The method for preparing aramid paper according to claim 1, characterized in that: The mass ratio of aramid fibrid to ANF fiber is 1-2:3-4; The water retention value of the aramid fibrid is 4.64-4.72 g / g, the average length of the aramid fibrid is 0.2-2 mm, the average diameter is 5-20 μm, and the aramid fibrid is para-aramid fibrid, meta-aramid fibrid or heterocyclic aramid fibrid; The average length of ANF fiber is 2-8 mm, the linear density is 110-130 tex, the breaking strength is 31-38 cN / dtex, the tensile modulus is 990-1050 cN / dtex, the breaking elongation is 3.05-3.46%, the initial decomposition temperature is 510-550°C, the residual carbon rate at 800°C is 60-70%, the crystallinity is 50-52%, and the crystal axis orientation index is 0.941-0.

955.

3. The method for preparing aramid paper according to claim 1, characterized in that: The specific process is: after aramid fibrils, ANF fibers and water are made into a mixed slurry, the mixed slurry is poured into a paper former for mixing, drying and hot rolling to obtain aramid paper.

4. The method for preparing aramid paper according to claim 3, characterized in that: The steps for preparing the mixed slurry are as follows: (a) after mixing aramid fibrid with water, dispersing, beating and debonding are carried out in sequence to obtain slurry a; meanwhile, after mixing ANF fiber with water, debonding is carried out to obtain slurry b; (b) Slurry a and slurry b are mixed and then dispersed to obtain a mixed slurry.

5. The method for preparing aramid paper according to claim 4, characterized in that: In step (a), the beating degree of slurry a is 65-70°SR, the concentration of slurry a is 0.7-1.0wt%, and the concentration of slurry b is 1.4-2.5wt%; When preparing slurry a, dispersion and beating are carried out in a trough beater, the knife load is 0 kg during dispersion, the dispersion time is 1 to 2 minutes, the knife load is 5 to 10 kg during beating, the beating time is 30 to 120 minutes, and defibrination is carried out in a fiber disintegrator, and the defibrination speed is 60,000 to 80,000 r. When preparing slurry b, the defiberization is carried out in a fiber disintegrator, and the defiberization speed is 6000-10000r; In step (b), the defiberization is carried out in a fiber disintegrator at a defiberization speed of 1000 to 2000 r.

6. The method for preparing aramid paper according to claim 3, characterized in that: The preparation process of the mixed slurry is as follows: after mixing aramid fibrils, ANF fibers and water, the aramid fibrils are dispersed, beaten and decomposed in sequence to obtain the mixed slurry.

7. The method for preparing aramid paper according to claim 6, characterized in that: Dispersion and beating are carried out in a trough beater. During dispersion, the knife load is 0kg and the dispersion time is 3-5min. During beating, the knife load is 12-16kg and the beating time is 150-180min. Defiberization is carried out in a fiber disintegrator and the defiberization speed is 10000-11000r.

8. The method for preparing aramid paper according to claim 3, characterized in that: During hot rolling forming, the hot pressing temperature is 260-300°C, the hot pressing pressure is 10-16MPa, the number of hot pressing times is 1-5 times, and the hot pressing time is 10-60s.

9. The method for preparing aramid paper according to claim 1, characterized in that: The preparation steps of ANF fibers are as follows: (i) Synthesis of XNB monomers; The structural formula of XNB monomer is as follows: (ii) preparing ANF solution; Under the protection of inert gas or nitrogen, DMAc and LiCl are first added to the reactor, stirring is started, and then p-phenylenediamine and XNB monomer are added. After being completely dissolved, the temperature is lowered to -4 to 0°C, and then the temperature of the reaction system is adjusted to 25 to 30°C, and terephthaloyl chloride is added in batches. After the addition is completed, the reaction is continued for 20 to 40 minutes, and finally LiOH is added for neutralization to obtain ANF solution; The molar ratio of p-phenylenediamine, XNB monomer, terephthaloyl chloride, DMAc, LiCl and LiOH is 1:1-1.2:3.1-3.5:100-1000:1-5:2-4; (iii) spinning; The ANF solution is centrifuged to remove salt and then placed in a reaction tank for degassing, followed by spinning, stretching, washing, drying, dry heat stretching, oiling, heat setting, and winding to obtain ANF fibers; The number of spinneret holes on the spinneret plate is 100 to 500, and the diameter of the spinneret holes is 0.08 mm; The spinning process parameters include: spinning solution temperature 20°C; metering pump speed 4-7r / min; spinneret speed 7-12m / min; air bath height 10-15mm; coagulation bath temperature 25-35°C; water washing temperature 70-90°C; dry heat stretching temperature 300-320°C; heat setting temperature 290-350°C; heat setting time 60-120s.

10. Aramid paper, characterized in that: The aramid paper is prepared by the method for preparing aramid paper according to any one of claims 1 to 9; the basis weight of the aramid paper is 60±1g / m 2 The thickness is 0.062-0.065mm, the tensile strength is 4.58-5.5kN / m, the tensile index is 48.1-51N·m / g, the elongation at break is 7.88-8.9%, the electrical strength is 25-45kV / mm, the effective diameter of the inhibition zone for Staphylococcus aureus is 1.86-1.99mm, the effective diameter of the inhibition zone for Escherichia coli is 2.01-2.45mm, and the effective diameter of the inhibition zone for Candida albicans is 3.77-4.21mm.

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