High-heat-insulation and high-purity phenolic aldehyde-based carbon fiber felt as well as preparation method and application thereof

Abstract

The invention relates to the field of special fibers. The invention provides a preparation method of a high-heat-insulation high-purity phenolic-based carbon fiber felt, which comprises the following steps: (1) reacting phenols and aldehydes under the action of a catalyst to obtain thermoplastic phenolic resin; (2) melting thermoplastic phenolic resin under the action of a cross-linking agent, and mixing the thermoplastic phenolic resin with a modifier to obtain modified phenolic resin; (3) carrying out melt spinning, curing crosslinking, washing and drying on the modified phenolic resin to obtain a phenolic fiber precursor; (4) carrying out the steps of chopping, opening, cotton carding, folding and needling on the phenolic fiber protofilament to obtain a phenolic fiber protofilament needled felt; and (5) carrying out high-temperature treatment on the phenolic fiber precursor needled felt to obtain the phenolic-based carbon fiber felt. The invention also provides the phenolic aldehyde-based carbon fiber felt. The invention also provides application of the phenolic aldehyde-based carbon fiber felt. The phenolic aldehyde-based carbon fiber felt prepared by the invention is uniform in texture, high in purity, good in high-temperature heat insulation performance, and easy for engineering amplification and large-scale industrial production.

Description

Technical Field

[0001] The invention belongs to the field of special fibers, and specifically relates to a high-insulation high-purity phenolic-based carbon fiber felt and a preparation method and application thereof. Background Art

[0002] Carbon fiber felt (hereinafter referred to as "carbon felt") has excellent high temperature resistance and heat insulation properties, especially in a high temperature environment of vacuum or inert gas above 1500°C, most materials such as metals and silicates have begun to melt, while carbon fiber felt can still maintain good thermal field stability without affecting various properties.

[0003] At present, domestic high-temperature thermal insulation carbon felt is mainly based on polyacrylonitrile and viscose. This type of carbon felt is limited by the properties of the original silk and fiber itself, and its comprehensive performance such as thermal insulation is relatively low. Its high-temperature thermal conductivity is relatively high and it is mainly used in the low-end thermal insulation industry. Phenolic-based carbon fiber felt prepared with phenolic resin as raw material has low high-temperature thermal conductivity and good high-temperature thermal insulation performance.

[0004] The reported research methods for phenolic carbon fiber felts include melt-blowing (CN118207689A) and electrospinning. The uniformity of carbon fiber diameter and the quality of felt produced by melt-blowing preparation process are too poor, which affects the overall performance of carbon fiber felt. The electrospinning felting process is only suitable for laboratory preparation, and the process is difficult to scale up and mass produce. Both methods have obvious defects and shortcomings.

[0005] Therefore, the prior art needs to be improved urgently. Summary of the invention

[0006] The present invention aims to provide a high-insulation high-purity phenolic carbon fiber felt and its preparation method and application in view of the deficiencies of the prior art. The purpose of the present invention is to provide a preparation method of phenolic carbon fiber felt with uniform texture, high purity and good high-temperature thermal insulation performance, and the preparation method is easy to scale up and industrialize, and can be applied to high-end high-temperature furnace insulation fields such as semiconductors, photovoltaics, and aerospace.

[0007] To solve the above problems, the present invention provides the following technical solutions: A method for preparing high-thermal insulation high-purity phenolic-based carbon fiber felt comprises the following steps: (1) Phenols and aldehydes react under the action of a catalyst to obtain thermoplastic phenolic resin; (2) The thermoplastic phenolic resin obtained in step (1) is melt-mixed with a modifier under the action of a cross-linking agent to obtain a modified phenolic resin; (3) The modified phenolic resin obtained in step (2) is melt-spinned, cured, cross-linked, washed and dried to obtain phenolic fiber precursor; (4) The phenolic fiber raw yarn obtained in step (3) is subjected to the steps of short cutting, opening, carding, folding, and needle punching to obtain a phenolic fiber raw yarn needle punched felt with a certain thickness and a certain density; (5) The phenolic fiber raw silk needle-punched felt obtained in step (4) is subjected to high temperature treatment to obtain phenolic-based carbon fiber felt.

[0008] The present invention uses thermoplastic resin as raw material, and prepares phenolic fiber precursor through resin modification, melt spinning, curing and cross-linking, washing and drying. Then, the phenolic fiber precursor is chopped, opened and carded to obtain fluffy and uniform phenolic fiber precursor mesh felt. Then, folding, needle-punching, and repeated folding and needle-punching are performed to obtain phenolic fiber precursor needle-punched felt with required thickness and density. Finally, high-temperature treatment is performed to obtain high-quality phenolic-based carbon fiber felt.

[0009] In the method for preparing the high-insulation high-purity phenolic-based carbon fiber felt as described above, the phenol in step (1) is any one of cresol, hydroquinone, resorcinol, and dimethylphenol, or a mixture of any two or more thereof.

[0010] In the method for preparing the high-insulation high-purity phenolic-based carbon fiber felt as described above, the aldehyde in step (1) is any one of formaldehyde and paraformaldehyde, or a mixture of any two or more thereof.

[0011] In the method for preparing the high-insulation high-purity phenolic-based carbon fiber felt as described above, the catalyst in step (1) is any one of hydrochloric acid, oxalic acid, sulfuric acid, and phosphoric acid, or a mixture of any two or more thereof.

[0012] In the method for preparing the high-insulation high-purity phenolic-based carbon fiber felt as described above, the cross-linking agent in step (2) is any one of m-phenylenediamine, isophoronediamine, melamine, p-phenylenediamine, and triethylamine, or a mixture of any two or more thereof.

[0013] In the method for preparing the high-insulation high-purity phenolic-based carbon fiber felt as described above, the modifier in step (2) is any one of polybutylene terephthalate, polyphenylene ether, polyvinyl butyral, bismaleimide, and polyamide, or a mixture of any two or more thereof.

[0014] In the method for preparing the high-insulation high-purity phenolic-based carbon fiber felt as described above, the melt spinning in step (3) is specifically as follows: the spinning temperature is 100-200°C, the drawing rate is 300-1000m / min, and the resin precursor with a uniform diameter of 5-20μm is spun.

[0015] In the method for preparing the high-insulation high-purity phenolic-based carbon fiber felt as described above, the reaction temperature of the curing and cross-linking in step (3) is 80-150°C.

[0016] In the method for preparing the high-insulation high-purity phenolic-based carbon fiber felt as described above, the length of the chopped phenolic fiber strands in step (4) is 5-20 cm.

[0017] In the method for preparing the high-insulation high-purity phenolic-based carbon fiber felt as described above, the combing in step (4) is mechanical combing or airflow combing, and the width of the phenolic fiber raw wire mesh felt is 0.5-2.0m.

[0018] In the method for preparing the high-insulation high-purity phenolic-based carbon fiber felt as described above, the folding and needling in step (4) are repeated folding and needling, wherein the number of folding and needling is 1-5 times.

[0019] In the method for preparing the high-insulation high-purity phenolic-based carbon fiber felt as described above, the temperature of the high-temperature treatment in step (5) is 1000-2800°C.

[0020] Based on the same inventive concept, the present invention provides a high-thermal-insulation high-purity phenolic-based carbon fiber felt, which is prepared according to the preparation method described above.

[0021] The high thermal insulation high purity phenolic-based carbon fiber felt as described above has a thickness of 2-20 mm and a density of 0.05-0.15 g / cm 3 , thermal conductivity at 1500℃ is 0.10-0.20 W / mK, and purity is 10-100ppm.

[0022] Based on the same inventive concept, the present invention provides a high thermal insulation and high purity phenolic-based carbon fiber felt prepared by the preparation method described above, or the application of the high thermal insulation and high purity phenolic-based carbon fiber felt described above in semiconductor, photovoltaic, and aerospace high temperature furnace insulation materials.

[0023] Compared with the existing technology, the effects and advantages of the present invention are: 1. The present invention provides a method for preparing a high-insulation high-purity phenolic carbon fiber felt, which uses a thermoplastic resin as a raw material, and obtains high-quality phenolic carbon fiber felt through resin modification, melt spinning, curing and cross-linking, washing and drying, short chopping, opening, carding, needling, repeated folding and needling, and high-temperature treatment. The present invention overcomes the shortcomings of the prior art, and the prepared phenolic carbon fiber felt has the characteristics of good uniformity, high purity, and good high-temperature thermal insulation performance. It is suitable for high-end high-temperature furnace insulation fields such as semiconductors, photovoltaics, and aerospace, and is easy to scale up and mass produce.

[0024] 2. The present invention provides a high-insulation high-purity phenolic-based carbon fiber felt with a thickness of 2-20 mm and a density of 0.05-0.15 g / cm 3The thermal conductivity at 1500℃ is 0.10-0.20 W / mK and the purity is 10-100ppm. It has excellent thermal insulation properties, is lightweight, and ensures the stability and reliability of the material at high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention is a schematic diagram of the preparation process of the high-thermal insulation high-purity phenolic-based carbon fiber felt. DETAILED DESCRIPTION

[0026] The following will combine the contents in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0028] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0029] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0030] Benzene cresol was purchased from Nanjing Datang Chemical Co., Ltd., CAS NO: 1319-77-3; Xylenol was purchased from Nanjing Datang Chemical Co., Ltd., CAS NO: 1300-71-6; Hydroquinone was purchased from Jiangsu Lisheng Chemical Co., Ltd., CAS NO: 123-31-9; Resorcinol was purchased from Jinan Liyang Chemical Co., Ltd., CAS NO: 108-46-3; Formaldehyde was purchased from Jinan Dianhua Chemical Technology Co., Ltd. with a concentration of 37.5%; Paraformaldehyde was purchased from Shandong Aldehyde Chemical Co., Ltd., CAS NO: 30525-89-4; Metaphenylenediamine was purchased from Nanjing Jirui Chemical Co., Ltd., CAS NO: 108-45-2; p-Phenylenediamine was purchased from Nanjing Jirui Chemical Co., Ltd., CAS NO: 106-50-3; Oxalic acid was purchased from Jiaxing Jiuxu Chemical Co., Ltd., CAS NO: 144-62-7; Hydrochloric acid was purchased from Maoming Xiongda Chemical Co., Ltd., CAS NO: 7647-01-0; Phosphoric acid was purchased from Shandong Gucheng Chemical Technology Co., Ltd., CAS NO: 7664-38-2; Sulfuric acid was purchased from Maoming Xiongda Chemical Co., Ltd., CAS NO: 7664-93-9; Triethylamine was purchased from Shandong Baihua Chemical Co., Ltd., CAS NO: 121-44-8; Isophorone diamine was purchased from Kain Chemical Company, CAS NO: 2855-13-2; Hexamethylenetetramine was purchased from Maoming Xiongda Chemical Co., Ltd., CAS NO: 100-97-0; Bismaleimide was purchased from Suzhou Qihang Biotechnology Co., Ltd., CAS NO: 106-50-3; Polybutylene terephthalate was purchased from Polyplastics of Japan, product model: C7640; Polyphenylene ether was purchased from Asahi Kasei Corporation, Japan, product model: 740V; Polyvinyl butyral was purchased from Hunan Yunbang Biotechnology Co., Ltd., product model: YB20419; Polyamide was purchased from Asahi Kasei Corporation of Japan, product model: 1300S.

[0031] A method for preparing high-thermal insulation high-purity phenolic-based carbon fiber felt comprises the following steps: (1) Phenols and aldehydes react under the action of a catalyst to obtain thermoplastic phenolic resin; (2) The thermoplastic phenolic resin obtained in step (1) is melt-mixed with a modifier under the action of a cross-linking agent to obtain a modified phenolic resin; (3) The modified phenolic resin obtained in step (2) is melt-spinned, cured, cross-linked, washed and dried to obtain phenolic fiber precursor; (4) The phenolic fiber raw yarn obtained in step (3) is subjected to the steps of short cutting, opening, carding, folding, and needle punching to obtain a phenolic fiber raw yarn needle punched felt with a certain thickness and a certain density; (5) The phenolic fiber raw silk needle-punched felt obtained in step (4) is subjected to high temperature treatment to obtain phenolic-based carbon fiber felt.

[0032] The present invention uses a self-made modified spinnable thermoplastic phenolic resin as a raw material, adopts a melt spinning process, and prepares a phenolic fiber precursor with highly uniform appearance and performance such as fiber diameter and strength, and then adopts a felting method of combing cotton and needle punching. After repeated folding and needle punching, the quality defects that may occur in a single-layer felt can be eliminated, and the texture uniformity of the precursor felt can be greatly improved. After high-temperature treatment, a high-quality phenolic-based carbon fiber felt is obtained. The present invention avoids the defects of uneven fiber diameter and uneven felt density of melt-blown felting, and does not have the problem that the electrospinning felting method is difficult to scale up, and can mass-produce high-quality phenolic-based carbon fiber felts with uniform texture.

[0033] In step (1) of the present invention, a thermoplastic phenolic resin having a softening point of 80°C-140°C and an average molecular weight of 500-1200 is synthesized by using phenols such as cresol, hydroquinone, resorcinol, and dimethylphenol and aldehydes such as formaldehyde and paraformaldehyde under the action of an acid as a catalyst. If the softening point and molecular weight are too low, for example, the softening point is lower than 80°C, the molecular chain is too short, and the average molecular weight is lower than 500, it is difficult to obtain a raw material resin with good spinnability even after subsequent high molecular weight polymer modification. Preferably, the thermoplastic phenolic resin prepared in step (1) has a softening point of 83°C-133°C and an average molecular weight of 515-1080.

[0034] In the method for preparing the high-insulation high-purity phenolic-based carbon fiber felt as described above, the phenol in step (1) is any one of cresol, hydroquinone, resorcinol, and dimethylphenol, or a mixture of any two or more thereof. Preferably, the phenol in step (1) is any one of cresol and hydroquinone. Under this condition, compared with the traditionally used phenol, the presence of groups such as methyl and phenolic hydroxyl groups can improve the strength of the phenolic resin after cross-linking. Most preferably, the phenol in step (1) is cresol.

[0035] In the method for preparing the high-insulation high-purity phenolic-based carbon fiber felt as described above, the aldehyde in step (1) is any one of formaldehyde and paraformaldehyde or a mixture of any two or more thereof. Preferably, the aldehyde in step (1) is any one of formaldehyde and paraformaldehyde, and the aldehyde condenses the phenolic monomer in the reactant into a chain phenolic resin. Under this condition, it is most preferred that the aldehyde in step (1) is formaldehyde.

[0036] In the method for preparing the high-insulation high-purity phenolic-based carbon fiber felt as described above, the catalyst in step (1) is any one of hydrochloric acid, oxalic acid, sulfuric acid, and phosphoric acid, or a mixture of any two or more thereof. Preferably, the catalyst in step (1) is oxalic acid.

[0037] In step (2) of the present invention, one or more high molecular weight polymers such as polybutylene terephthalate, polyphenylene ether, polyvinyl butyral, bismaleimide, polyamide, etc. are melt-mixed into the prepared thermoplastic phenolic resin, and amino groups in cross-linking agents such as m-phenylenediamine, isophorone diamine, melamine, p-phenylenediamine, triethylamine, etc. react with phenolic hydroxyl groups in the phenolic resin to generate new CN bonds, so that the molecules of the phenolic resin are further cross-linked, the molecular weight is increased, and the spinnability of the resin body is improved; at the same time, the amino groups in the cross-linking agent can also be cross-linked to a certain extent with functional groups such as hydroxyl groups in the modifier, and are uniformly dispersed in the resin matrix, thereby further improving the spinnability and drawability of the thermoplastic phenolic resin, which is beneficial to the subsequent melt spinning of fibers.

[0038] In the method for preparing high-insulation high-purity phenolic-based carbon fiber felt as described above, the cross-linking agent in step (2) is any one of m-phenylenediamine, isophorone diamine, melamine, p-phenylenediamine, and triethylamine, or a mixture of any two or more thereof. Preferably, the cross-linking agent in step (2) is any one of m-phenylenediamine, triethylamine, and p-phenylenediamine. The amino groups in these three cross-linking agents have better reactivity with functional groups such as phenolic hydroxyl groups in phenolic resin and hydroxyl groups in modifiers, which is beneficial to further improve the drawability of thermoplastic phenolic resin and the subsequent melt spinning of fibers. Under this condition, it is most preferred that the cross-linking agent in step (2) is m-phenylenediamine.

[0039] In the method for preparing the high-insulation high-purity phenolic-based carbon fiber felt as described above, the modifier in step (2) is any one of polybutylene terephthalate, polyphenylene ether, polyvinyl butyral, bismaleimide, and polyamide, or a mixture of any two or more thereof. Preferably, the modifier in step (2) is any one of polybutylene terephthalate and polyphenylene ether, or a mixture of any two or more thereof. Most preferably, the modifier in step (2) is polybutylene terephthalate.

[0040] In step (3) of the present invention, the modified spinnable phenolic resin can be fully stretched during the melt spinning process and is not prone to breaking, thereby obtaining uncured phenolic raw fibers with uniform fiber diameters. The chain phenolic resin molecules are then cross-linked into a three-dimensional cross-linked structure through a cross-linking reaction of a curing liquid, and after washing and drying, phenolic fiber raw fibers with uniform fiber diameters and a dense structure are obtained.

[0041] In the method for preparing the high-insulation high-purity phenolic-based carbon fiber felt as described above, the melt spinning in step (3) is specifically as follows: the spinning temperature is 100-200°C, the drawing rate is 300-1000m / min, and the resin precursor with a uniform diameter of 5-20μm is spun. Preferably, the melt spinning in step (3) is specifically as follows: the spinning temperature is 130-180°C, and the drawing rate is 500-900m / min. Under this condition, the viscosity and drawing ratio of the raw resin are moderate, and the resin precursor with a uniform diameter of 8-16μm is spun, taking into account the flexibility and strength of the uncured precursor.

[0042] In step (3) of the present invention, curing and crosslinking are carried out in the presence of a crosslinking agent in a solution with hydrochloric acid, phosphoric acid or other acid as a catalyst, and the reaction temperature is 80-150°C to obtain phenolic fiber precursor. Preferably, the reaction temperature of curing and crosslinking in step (3) is 90-150°C. Most preferably, the reaction temperature of curing and crosslinking in step (3) is 90-120°C. In step (3), the crosslinking agent for curing and crosslinking is any one of formaldehyde, paraformaldehyde and hexamethylenetetramine.

[0043] In step (4) of the present invention, the phenolic fiber raw yarn is subjected to the steps of short cutting, opening, carding, folding and needle punching to obtain a phenolic fiber raw yarn needle punched felt with a certain thickness and a certain density.

[0044] In the method for preparing the high-insulation high-purity phenolic-based carbon fiber felt as described above, the length of the chopped phenolic fiber precursor in step (4) is 5-20 cm. Optionally, the length of the chopped phenolic fiber precursor in step (4) is 6-20 cm. Optionally, the length of the chopped phenolic fiber precursor in step (4) is 6-15 cm. Preferably, the length of the chopped phenolic fiber precursor in step (4) is 10 cm.

[0045] In the method for preparing the high-insulation high-purity phenolic-based carbon fiber felt as described above, the cotton combing in step (4) is mechanical cotton combing or air-flow cotton combing, and the width of the phenolic fiber original wire mesh felt is 0.5-2.0m. According to the size requirements of the target phenolic-based carbon fiber felt. Preferably, the cotton combing in step (4) is mechanical cotton combing, and the width of the phenolic fiber original wire mesh felt is 1-2m. Preferably, the cotton combing in step (4) is mechanical cotton combing, and the width of the phenolic fiber original wire mesh felt is 1.5m.

[0046] In the method for preparing the high-insulation high-purity phenolic-based carbon fiber felt as described above, the folding and needling in step (4) are repeated folding and needling, wherein the number of folding and needling is 1-5 times. Preferably, the number of folding and needling is 3-4 times. If the phenolic fiber raw wire mesh felt after carding is directly needled, the phenolic fiber needle-punched felt and the subsequent phenolic-based carbon felt will have the same uneven defect due to the unevenness of the initial mesh felt. After repeated folding and needling, this quality defect can be eliminated, and a high-quality phenolic fiber raw wire needle-punched felt with uniform texture can be obtained.

[0047] According to the method for preparing the high-insulation high-purity phenolic-based carbon fiber felt, the phenolic fiber raw silk needle-punched felt of a certain thickness and a certain density in step (4) has a thickness of 5-25 mm and a density of 0.05-0.20 g / cm 3 Preferably, the phenolic fiber raw silk needle felt of a certain thickness and a certain density in step (4) is 12-25 mm in thickness and 0.12-0.20 g / cm in density. 3 Optionally, the phenolic fiber raw silk needle felt of a certain thickness and a certain density in step (4) is 15-20 mm thick and 0.15-0.17 g / cm2 in density. 3 Phenolic fiber raw silk needle felt.

[0048] In step (5) of the present invention, the phenolic fiber raw yarn needle-punched felt is subjected to high temperature treatment to obtain phenolic-based carbon fiber felt. The three-dimensional cross-linked molecular structure of the phenolic fiber made of phenolic resin as the raw material is directly carbonized without going through the melting rearrangement stage during high-temperature carbonization. Adjacent carbon molecular clusters are cross-arranged, and it is difficult to form a neatly arranged graphite lattice structure. It has low high-temperature thermal conductivity and good high-temperature thermal insulation performance.

[0049] In the method for preparing the high-insulation high-purity phenolic-based carbon fiber felt as described above, the heating rate of the high-temperature treatment in step (5) is 100-180°C / min. Preferably, the heating rate of the high-temperature treatment in step (5) is 150-180°C / min.

[0050] In the method for preparing the high-insulation high-purity phenolic carbon fiber felt as described above, the temperature of the high-temperature treatment in step (5) is 1000-2800°C. Preferably, the temperature of the high-temperature treatment in step (5) is 1500-2800°C. The high-temperature treatment at this temperature can remove N, O heteroatoms and other metal heteroatoms in the fiber to obtain a high-purity phenolic carbon fiber felt. Preferably, the temperature of the high-temperature treatment in step (5) is 1800-2800°C.

[0051] Based on the same inventive concept, the present invention provides a high-thermal-insulation high-purity phenolic-based carbon fiber felt, which is prepared according to the preparation method described above.

[0052] The high thermal insulation high purity phenolic carbon fiber felt as described above has a thickness of 2-20 mm and a density of 0.05-0.15 g / cm 3 , the thermal conductivity at 1500°C is 0.10-0.20 W / mK, and the purity is 10-100 ppm. Preferably, the high thermal insulation high purity phenolic carbon fiber felt has a thickness of 8-20 mm and a density of 0.08-0.15 g / cm 3 , thermal conductivity at 1500℃ is 0.12-0.16 W / mK, and purity is 10-80ppm.

[0053] Based on the same inventive concept, the present invention provides a high thermal insulation and high purity phenolic-based carbon fiber felt prepared by the preparation method described above, or the application of the high thermal insulation and high purity phenolic-based carbon fiber felt described above in semiconductor, photovoltaic, and aerospace high temperature furnace insulation materials.

[0054] Figure 1 Schematic diagram of the preparation process of the high-insulation high-purity phenolic-based carbon fiber felt of the present invention. Figure 1 As shown, the present invention provides a method for preparing high-insulation high-purity phenolic-based carbon fiber felt, comprising the following steps: phenols and aldehydes react under the action of a catalyst to obtain a thermoplastic phenolic resin; the thermoplastic phenolic resin is melted and mixed with a modifier under the action of a cross-linking agent to obtain a modified phenolic resin; the modified phenolic resin is melt-spun, cured and cross-linked, washed and dried to obtain a phenolic fiber precursor; the phenolic fiber precursor is subjected to the steps of short-cutting, opening, carding, folding, and needle-punching to obtain a phenolic fiber precursor needle-punched felt; the phenolic fiber precursor needle-punched felt is subjected to high-temperature treatment to obtain a phenolic-based carbon fiber felt. The specific steps and parameters are shown in the embodiment.

[0055] Example 1 Thermoplastic phenolic resin with a softening point of 112°C and an average molecular weight of 710 was synthesized by reacting cresol, formaldehyde and oxalic acid (molar ratio of 1:0.88:0.02) at 98°C for 3.5 hours, and 8% polybutylene terephthalate (polybutylene terephthalate) was melt-mixed into the thermoplastic phenolic resin under the action of cross-linking agent m-phenylenediamine (accounting for 1.2% of the mass of the thermoplastic phenolic resin); melt spinning was carried out at 160°C, and the drafting rate was 700 m / min to spin phenolic resin precursor with a diameter of 12 microns. Then, the phenolic fiber precursor was cross-linked and cured at 120°C in a mixed solution of polyformaldehyde (concentration 18%) and hydrochloric acid (concentration 15%), washed and dried to obtain phenolic fiber precursor, which was chopped to 10 cm and then opened and combed. Mechanical combing was used, and the width of the phenolic fiber precursor felt was 1.5 meters.

[0056] The phenolic fiber raw wire mesh was folded and needled, and the folding and needled were repeated three times to obtain a thickness of 15 mm and a density of 0.15 g / cm 3 The phenolic fiber raw silk needle felt was then heated to 2800℃ at 150℃ / min and kept at this temperature for 1 hour to obtain a 12mm thick and 0.10g / cm 3 High quality phenolic carbon fiber felt, the thermal conductivity of the phenolic carbon fiber felt is 0.14W / mK at 1500℃ and the purity is 10ppm.

[0057] Example 2 Hydroquinone, polyformaldehyde, and hydrochloric acid (molar ratio 1:0.85:0.015) react at 95°C for 3.0 hours to synthesize a thermoplastic phenolic resin with a softening point of 105°C and an average molecular weight of 650. Under the action of triethylamine (accounting for 1.5% of the mass of the thermoplastic phenolic resin), 2% polyphenylene ether and 1% bismaleimide accounting for the mass of the thermoplastic phenolic resin are melt-mixed; melt spinning is carried out at 140°C, and the drafting rate is 900 m / min to spin out resin precursor with a diameter of 8 microns. Then, it is cross-linked and cured at 90°C in a mixed solution of formaldehyde (concentration 16%) and phosphoric acid (concentration 12%), washed and dried to obtain phenolic fiber precursor, which is chopped to 15 cm and then opened and combed. Mechanical combing is used, and the width of the phenolic fiber precursor mesh is 2 meters.

[0058] The phenolic fiber raw wire mesh felt was folded and needled, and the folding and needled were repeated 4 times to obtain a thickness of 20 mm and a density of 0.17 g / cm 3 The phenolic fiber raw silk needle felt was then heated to 1800℃ at 100℃ / min and kept at this temperature for 2 hours to obtain a 16mm thick and 0.12g / cm 3 High quality phenolic carbon fiber felt, the thermal conductivity of the phenolic carbon fiber felt is 0.15W / mK at 1500℃ and the purity is 60ppm.

[0059] Embodiment 3: Thermoplastic phenolic resin with a softening point of 83°C and an average molecular weight of 515 was synthesized by reacting dimethylphenol, formaldehyde and sulfuric acid (molar ratio 1:0.82:0.01) at 96°C for 2.5 hours, and 5% polyvinyl butyral accounting for the mass of thermoplastic phenolic resin was melt-mixed under the action of cross-linking agent isophorone diamine (accounting for 1.0% of the mass of thermoplastic phenolic resin); melt spinning was carried out at 130°C, and the drafting rate was 600 m / min to spin phenolic resin precursor with a diameter of 14 microns. Then, it was cross-linked and cured at 150°C in a mixed solution of hexamethylenetetramine (concentration 15%) and hydrochloric acid (concentration 13%), washed and dried to obtain phenolic fiber precursor, which was chopped to 6 cm and then opened and combed. Air-flow combing was used, and the width of the phenolic fiber precursor felt was 1.0 m.

[0060] The phenolic fiber raw wire mesh felt was folded and needled, and the folding and needled were repeated 5 times to obtain a thickness of 25 mm and a density of 0.20 g / cm 3 The phenolic fiber raw silk needle felt was then heated to 2400℃ at 120℃ / min and kept at this temperature for 1.5 hours to obtain a 20mm thick and 0.15g / cm 3 High quality phenolic carbon fiber felt, the thermal conductivity of the phenolic carbon fiber felt at 1500℃ is 0.16W / mK and the purity is 30ppm.

[0061] Embodiment 4: Resorcinol, formaldehyde, phosphoric acid (molar ratio 1:0.80:0.012) react at 93℃ for 4.5 hours to synthesize a thermoplastic phenolic resin with a softening point of 133℃ and an average molecular weight of more than 1080. Under the action of cross-linking agent p-phenylenediamine (accounting for 0.8% of the mass of the thermoplastic phenolic resin), 2% polyvinyl butyral, 2% bismaleimide, and 2% polyamide accounting for the mass of the thermoplastic phenolic resin are melt-mixed; melt spinning is carried out at 180℃, and the drafting rate is 500 meters / minute to spin phenolic resin precursor with a diameter of 16 microns. Then, it is cross-linked and cured at 100℃ in a mixed solution of formaldehyde (concentration 17%) and hydrochloric acid (concentration 14%), washed and dried to obtain phenolic fiber precursor, which is chopped to 20 cm and then opened and combed. Mechanical combing is used, and the width of the phenolic fiber precursor mesh is 1.25 meters.

[0062] The phenolic fiber raw wire mesh felt was folded and needled, and the folding and needled were repeated twice to obtain a thickness of 12 mm and a density of 0.12 g / cm 3 The phenolic fiber raw silk needle felt was then heated to 1500℃ at 180℃ / min and kept at this temperature for 2.5 hours to obtain a felt with a thickness of 8mm and a density of 0.08g / cm 3 High quality phenolic carbon fiber felt, the thermal conductivity of the phenolic carbon fiber felt at 1500℃ is 0.12W / mK and the purity is 80ppm.

[0063] Comparative Example 1: Thermoplastic phenolic resin with a softening point of 112°C and an average molecular weight of 710 was synthesized by reacting cresol, formaldehyde and oxalic acid (molar ratio 1:0.88:0.02) at 98°C for 3.5 hours. The melt spinning was carried out at 160°C, and the drafting rate was 700 m / min. There were many broken ends during spinning, and the diameter of the raw fiber was 20-30 microns, and the uniformity was poor. Then, the raw fiber was cross-linked and cured at 120°C in a mixed solution of polyformaldehyde (concentration 18%) and hydrochloric acid (concentration 15%), and then washed and dried to obtain phenolic fiber raw fiber. The phenolic fiber raw fiber was chopped to 10 cm and then opened for mechanical combing. Because it was not modified with a high molecular polymer, the raw resin had poor drafting properties, and the fiber diameter was thick and uneven. Too thick a fiber diameter would increase the fiber brittleness, and it could not pass the subsequent combing process, and the subsequent felting process could not be carried out.

[0064] Comparative Example 2: Hydroquinone, polyformaldehyde, and hydrochloric acid (molar ratio 1:0.85:0.015) react at 95°C for 3.0 hours to synthesize a thermoplastic phenolic resin with a softening point of 105°C and an average molecular weight of 650. Under the action of triethylamine (accounting for 1.5% of the mass of the thermoplastic phenolic resin), 2% polyphenylene ether and 1% bismaleimide accounting for the mass of the thermoplastic phenolic resin are melt-mixed; melt spinning is carried out at 140°C, and the drafting rate is 900 m / min to spin out resin precursor with a diameter of 8 microns. Then, it is cross-linked and cured at 90°C in a mixed solution of formaldehyde (concentration 16%) and phosphoric acid (concentration 12%), washed and dried to obtain phenolic fiber precursor, which is chopped to 15 cm and then opened and combed. Mechanical combing is used, and the width of the phenolic fiber precursor mesh is 2 meters.

[0065] The phenolic fiber raw wire mesh felt was folded and needled without repeated folding and needled to obtain a thickness of 3 mm and a density of 0.05 g / cm 3 The phenolic fiber raw silk needle felt was then heated to 1800℃ at 100℃ / min and kept at this temperature for 2 hours to obtain a 2mm thick and 0.025g / cm 3 The phenolic-based carbon fiber felt has obvious uneven defects between the phenolic fiber needle-punched felt and the phenolic-based carbon felt because it has not been repeatedly folded and needle-punched. The thermal conductivity of the phenolic-based carbon fiber felt at 1500℃ is 0.25W / mK, and the purity is 60ppm.

[0066] It should be pointed out that the specific implementation methods are only representative examples of the present invention. Obviously, the technical solution of the present invention is not limited to the above-mentioned embodiments, and there are many variations. Those skilled in the art who can obtain the invention clearly disclosed in the present invention or without objection based on the written description of the document should be considered as the scope of protection of this patent.

Claims

1. A method for preparing high-insulation high-purity phenolic-based carbon fiber felt, characterized in that: The following steps are involved: (1) Phenols and aldehydes react under the action of a catalyst to obtain thermoplastic phenolic resin; (2) The thermoplastic phenolic resin obtained in step (1) is melt-mixed with a modifier under the action of a cross-linking agent to obtain a modified phenolic resin; (3) The modified phenolic resin obtained in step (2) is melt-spinned, cured, cross-linked, washed and dried to obtain phenolic fiber precursor; (4) The phenolic fiber raw yarn obtained in step (3) is subjected to the steps of short cutting, opening, carding, folding, and needle punching to obtain a phenolic fiber raw yarn needle punched felt with a certain thickness and a certain density; (5) The phenolic fiber raw silk needle-punched felt obtained in step (4) is subjected to high temperature treatment to obtain phenolic-based carbon fiber felt.

2. The method for preparing high-thermal-insulation high-purity phenolic-based carbon fiber felt according to claim 1, characterized in that: The cross-linking agent in step (2) is any one of m-phenylenediamine, isophoronediamine, melamine, p-phenylenediamine, and triethylamine, or a mixture of any two or more thereof.

3. The method for preparing high-thermal-insulation high-purity phenolic-based carbon fiber felt according to claim 1, characterized in that: The modifier in step (2) is any one of polybutylene terephthalate, polyphenylene ether, polyvinyl butyral, bismaleimide, and polyamide, or a mixture of any two or more thereof.

4. The method for preparing high-thermal-insulation high-purity phenolic-based carbon fiber felt according to claim 1, characterized in that: The melt spinning in step (3) is specifically as follows: the spinning temperature is 100-200° C., the drawing rate is 300-1000 m / min, and the resin raw fibers with a uniform diameter of 5-20 μm are spun.

5. The method for preparing high-thermal-insulation high-purity phenolic-based carbon fiber felt according to claim 1, characterized in that: The reaction temperature of curing and cross-linking in step (3) is 80-150°C.

6. The method for preparing high-thermal-insulation high-purity phenolic-based carbon fiber felt according to claim 1, characterized in that: In the step (4), the folding and needling are repeated folding and needling, wherein the number of folding and needling is 1-5 times.

7. The method for preparing high-thermal-insulation high-purity phenolic-based carbon fiber felt according to claim 1, characterized in that: The temperature of the high temperature treatment in step (5) is 1000-2800°C.

8. A high-insulation high-purity phenolic-based carbon fiber felt, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 7.

9. The high thermal insulation high purity phenolic-based carbon fiber felt according to claim 8, characterized in that: The high-insulation high-purity phenolic-based carbon fiber felt has a thickness of 2-20 mm and a density of 0.05-0.15 g / cm 3 , thermal conductivity at 1500℃ is 0.10-0.20 W / mK, and purity is 10-100ppm.

10. Application of the high thermal insulation and high purity phenolic-based carbon fiber felt prepared by the preparation method according to any one of claims 1 to 7 or the high thermal insulation and high purity phenolic-based carbon fiber felt according to any one of claims 8 to 9 in semiconductor, photovoltaic, and aerospace high temperature furnace insulation materials.

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