CN108203848A - A kind of hot high modulus pitch-based carbon fiber of high-strength highly-conductive and preparation method thereof - Google Patents

Abstract

The invention discloses hot high modulus pitch-based carbon fibers of a kind of high-strength highly-conductive and preparation method thereof, belong to technical field of carbon fiber preparation.Technical solution includes step：1) using mesophase pitch as raw material, the pitch based precursor that fibre diameter is 10 μm~30 μm is prepared through melt spinning；2) after asphaltic base gray filament winding made from step 1) being received silk, silk is received by active release silk, hot-rolling drying process, cure treatment, three-level charing process, pre- graphitization processing, graphitization processing, starching drying and final winding successively, the hot high modulus pitch-based carbon fiber of high-strength highly-conductive is prepared.The present invention passes through the introducing dried to hot-rolling, upgrading optimization, the classification again of charring process, the pre- graphited introducing of curing process, so as to reduce graphitization final temperature, in the Pitch-Based Graphite Fibers for preparing identical heat conduction, graphitization temperature is lower needed for this method, the service life of graphite heater is greatly extended, realizes the industrialization of high heat conduction Pitch-Based Graphite Fibers.

Description

A kind of pitch-based carbon fiber with high strength, high thermal conductivity and high modulus and preparation method thereof

technical field

The invention belongs to the technical field of carbon fiber preparation, and in particular relates to a pitch-based carbon fiber with high strength, high thermal conductivity and high modulus and a preparation method thereof.

Background technique

Pitch-based carbon fiber is a special fiber with a carbon content greater than 92% that is produced from petroleum pitch, coal pitch, and naphthalene through refining, spinning, pre-oxidation, carbonization, or graphitization of pitch. It is a new material with excellent mechanical properties. The tensile strength of carbon fiber resin composite materials is generally above 3500Mpa, which is 7 to 9 times that of steel, and the tensile modulus of elasticity is 230 to 430Gpa, which is also higher than that of steel. It has excellent properties such as high strength, high modulus, high temperature resistance, corrosion resistance, fatigue resistance, creep resistance, electrical conductivity and thermal conductivity, and is an indispensable engineering material in the aerospace industry.

However, in the actual production process, in order to prepare graphite fibers with higher modulus and thermal conductivity, it is necessary to improve the thermal conductivity of the fibers by increasing the graphitization temperature. Shortening limits the realization of the industrialization of high thermal conductivity graphite fibers.

Contents of the invention

The purpose of the present invention is to provide a high-strength, high-thermal-conductivity, high-modulus pitch-based carbon fiber and a preparation method thereof. The preparation method is simple in operation, strong in controllability, and prolongs the service life of a graphite heating element, thereby realizing a pitch-based graphite fiber with high thermal conductivity. industrialization.

The present invention is achieved through the following technical solutions:

The invention discloses a preparation method of pitch-based carbon fiber with high strength, high thermal conductivity and high modulus, which comprises the following steps:

1) Using mesophase pitch as a raw material, the pitch-based precursor fiber with a fiber diameter of 10 μm to 30 μm is prepared by melt spinning;

2) After the pitch-based raw silk obtained in step 1) is wound and collected, it is sequentially subjected to active unwinding, hot roller drying treatment, non-melting treatment, three-stage carbonization treatment, pre-graphitization treatment, graphitization treatment, and sizing and drying And the final winding and winding to prepare pitch-based carbon fibers with high strength, high thermal conductivity and high modulus.

Preferably, from the active wire feeding operation to the final winding and receiving process, the entire line running speed of the equipment operation line is 0.15m/min˜1m/min.

Preferably, the hot roller drying (the number of drying rollers is 2 to 4) is at 150°C to 220°C for 500s to 900s.

Preferably, the non-melting treatment is carried out at a temperature of 240°C to 350°C, a draft of 0.1% to 2%, a compressed air flow rate of 0.1m ³ /h to 10m ³ /h, and the treatment time is 700s ~2000s.

Preferably, the three-stage carbonization treatment specifically means that the fibers after the non-melting treatment are subjected to low-temperature carbonization treatment, medium-temperature carbonization treatment and high-temperature carbonization treatment in sequence; wherein, 5 temperature zones are set during the low-temperature carbonization treatment and medium-temperature carbonization treatment; 4 temperature zones are set during the carbonization process.

Further preferably, the low-temperature carbonization treatment is carried out in a nitrogen atmosphere at 400°C to 700°C and the stretching condition is -1% to -2%, for 200s to 500s; the medium temperature carbonization treatment is carried out in a nitrogen atmosphere at 800°C ～1200℃, drafting -1%～-2%, treatment 200s～500s; high temperature carbonization treatment is under nitrogen atmosphere, 1200℃～1800℃, drafting 0.5%～1.5% conditions, treatment 200s～400s.

Further preferably, the pre-graphitization treatment is performed in an argon atmosphere at 2100° C. to 2300° C. and a stretching of 0.5% to 1% for 100s to 200s.

Further preferably, the graphitization treatment temperature is under the conditions of 2600° C. to 2800° C. and a stretching of 1% to 1.5% in an argon atmosphere for 100s to 200s.

Preferably, the sizing and drying is performed with an epoxy resin-based sizing agent, and the fiber sizing rate is controlled at 1.0% to 3.0%; the drying is performed at 150°C to 200°C.

The present invention also discloses the high-strength, high-thermal-conduction, high-modulus pitch-based carbon fiber prepared by the above-mentioned preparation method. The high-strength, high-thermal-conduction, high-modulus pitch-based carbon fiber has a tensile strength above 3300MPa, a modulus above 800GPa, and a thermal conductivity of 500W. /m*K or above, bulk density above 2.17g/cm ³ .

Compared with the prior art, the present invention has the following beneficial technical effects:

The preparation method of pitch-based carbon fiber with high strength, high thermal conductivity and high modulus disclosed by the present invention uses mesophase pitch as a raw material, prepares pitch-based precursors with a fiber diameter of 10 μm to 30 μm by melt spinning, and then winds the pitch-based precursors After the wire is collected, the high-strength, high-thermal-conductivity, high-modulus asphalt is prepared through active wire release, hot roller drying treatment, non-melting treatment, three-stage carbonization treatment, pre-graphitization treatment, graphitization treatment, sizing drying, and winding and winding. base carbon fiber. First of all, the introduction of hot roller drying treatment makes the fiber fully dry during the process of passing through the hot roller, and then the non-melting treatment process is more conducive to the infiltration of oxygen, so that the oxidation is more sufficient and the oxygen distribution in the radial direction is more uniform. Secondly, the introduction of the three-stage carbonization treatment makes the carbonization treatment time of the fiber longer, the orientation degree of the fiber is maintained, and the severe reaction that avoids damage to the structure of the fiber is beneficial to the improvement of the mechanical properties of the fiber, and at the same time makes the fiber more dense. , which is conducive to the increase of fiber density. Thirdly, the introduction of pre-graphitization can apply greater draft to the fiber, which is beneficial to improve the degree of densification of the fiber, which leads to the improvement of fiber mechanics, thermal conductivity and bulk density. After high-temperature graphitization treatment, the degree of graphitization of the fiber Higher, higher density, which is conducive to the improvement of fiber strength, modulus and thermal conductivity. The method of the invention has simple operation, smooth operation of the whole line and strong controllability.

Further, the three-stage carbonization treatment specifically means that the fibers after the non-melting treatment are subjected to low-temperature carbonization treatment, medium-temperature carbonization treatment and high-temperature carbonization treatment in sequence; wherein, five temperature zones are set during the low-temperature carbonization treatment and medium-temperature carbonization treatment; 4 temperature zones are set during the carbonization process. This division of temperature zones is more reasonable, the temperature difference between adjacent temperature zones is smaller, and the temperature rise slope of the carbonization section is smaller.

Furthermore, the introduction of pre-graphitization can ensure that the condensation and denitrification reaction of the fiber is completed at 2100°C to 2300°C, the porosity Vp reaches the highest value, and the R value of the Raman spectrum shows an inflection point around 2200°C, indicating that the graphite layer is orderly. The stacking degree began to gradually improve.

When the present invention prepares fibers with the same thermal conductivity, the graphitization temperature is reduced by 100°C to 150°C. Taking graphite fibers with a thermal conductivity of 500W/m*K in the prior art as an example, the domestic graphitization temperature should be 2700 °C ± 50 °C, but produced according to the preparation method of the present invention, its graphitization temperature is 2500 °C ± 50 °C. At the same time, the service life of the graphite heating element is extended by more than 2 times.

Detailed ways

The present invention will be further described in detail below in conjunction with specific embodiments, which are explanations of the present invention rather than limitations.

The preparation method of the pitch-based carbon fiber with high strength, high thermal conductivity and high modulus disclosed in the present invention, the basic process flow is as follows:

Precursor spinning—winding and receiving—active unwinding—hot roller drying—non-melting treatment—low temperature carbonization treatment—medium temperature carbonization treatment—high temperature carbonization treatment—pre-graphitization treatment—graphitization treatment—sizing treatment—drying—winding Shrink.

Taking 1K pitch-based raw silk as an example, the specific process steps are as follows:

Step 1: Using mesophase pitch as a raw material, 1K pitch-based precursors are prepared by melt spinning, and the fiber diameter is 10 μm to 30 μm. For the specific preparation method of the raw silk, please refer to the contents disclosed in the application number 201410307876.0 and the publication number CN104047066A.

Step 2: After the pitch-based raw silk obtained in step 1) is wound and collected, it is sequentially subjected to active unwinding, hot roller drying treatment, non-melting treatment, three-stage carbonization treatment, pre-graphitization treatment, graphitization treatment, and sizing Drying and final winding to prepare 1K pitch-based carbon fiber with high strength, high thermal conductivity and high modulus. The running speed of the whole line is 0.15m/min～1m/min.

2.1. Heat roller drying treatment (the number of drying rollers is 2 to 4), the drying temperature is 150°C to 220°C, and the time is controlled at 500s to 900s.

2.2. Non-melting treatment, the treatment temperature is 240℃～350℃, the drafting is 0.1%～2%, the compressed air flow rate is 0.1m ³ /h～10m ³ /h, and the residence time of the fiber in the furnace is controlled at 700s～2000s.

2.3. Low-temperature carbonization treatment, 5 temperature zones, treatment temperature 400℃～700℃, drafting -1%～-2%, nitrogen protection, fiber residence time in the furnace is controlled at 200s～500s.

2.4, medium temperature carbonization treatment, 5 temperature zones, treatment temperature 800℃～1200℃, drafting -1%～-2%, nitrogen protection, fiber residence time in the furnace is controlled at 200s～500s.

2.5. High temperature carbonization treatment, 4 temperature zones, treatment temperature 1200℃～1800℃, drafting 0.5%～1.5%, nitrogen protection, fiber residence time in the furnace is controlled at 200s～400s.

2.6. Pre-graphitization treatment, the treatment temperature is 2100 ℃ ~ 2300 ℃, the draft is 0.5% ~ 1%, the argon gas is protected, and the fiber stays in the furnace for 100s ~ 200s.

2.7. Graphitization treatment, the treatment temperature is 2600°C-2800°C, the draft is 1%-1.5%, protected by argon, and the fiber stays in the furnace for 100s-200s.

2.8. Use epoxy resin-based sizing agent for sizing treatment (the concentration of sizing solution is 1.0% to 3.0%). The fiber sizing rate is controlled at 1.0% to 3.0%, and then dried. The drying temperature is controlled at 150°C to 200°C.

2.9. Winding and receiving.

Example 1

A method for preparing pitch-based carbon fibers with high strength, high thermal conductivity and high modulus, comprising the following steps:

1) Using mesophase pitch as raw material, 1K pitch-based precursors were prepared by melt spinning, and the fiber diameter (average value) was 15 μm;

2) Carry out hot roller drying treatment, the treatment temperature of four drying rollers is 150°C, 170°C, 190°C, 210°C in sequence, and the residence time of fibers on the hot roller is controlled at 650s;

3) After being drawn by three rollers, it enters the oxidation furnace for non-melting treatment. The starting temperature of the treatment is 240°C and the final temperature is 300°C (making the draft reach 1%). The compressed air flow rate is 6m ³ /h, and the fiber stays in the furnace The time is controlled at 1000s;

4) After being drawn by three rollers, it enters the low-temperature carbonization furnace for low-temperature carbonization treatment. The treatment temperature starts at 450°C and ends at 700°C (the first zone is 450°C, the second zone, 525°C, the third zone, 600°C and the fourth zone is 650°C) , five zones, 700°C) (drawing -1.5%), nitrogen protection, the residence time of the fiber in the furnace is controlled at 400s; it enters the final temperature carbonization furnace through three rollers, and carries out medium temperature carbonization treatment. The treatment temperature starts at 800°C, The final temperature is 1000°C (800°C in the first zone, 850°C in the second zone, 900°C in the third zone, 950°C in the fourth zone, 1000°C in the fifth zone) (drawing -1%), nitrogen protection, and the residence time of the fiber in the furnace is controlled at 400s ; After entering the high-temperature carbonization furnace through five-roll rollers, high-temperature carbonization treatment is carried out. The treatment temperature starts at 1200°C and ends at 1800°C (the first zone is 1200°C, the second zone is 1400°C, the third zone is 1600°C, and the fourth zone is 1800°C) (drawing 0.5%), nitrogen protection, the residence time of the fiber in the furnace is controlled at 200s;

5) Pre-graphitization treatment is carried out on the five-roller roller, the treatment temperature is 2200°C (drawing 0.75%), the argon gas protection is used, and the residence time of the fiber in the furnace is controlled at 150s;

6) Pass five rollers for graphitization treatment, the treatment temperature is 2600°C (drawing 1.5%), and the residence time of the argon-protected fiber in the furnace is controlled at 100s;

7) Epoxy resin-based sizing agent is used for sizing treatment, the fiber sizing rate is controlled at 1.0% to 3.0%, and then dried, and the drying temperature is controlled at 150°C to 200°C; winding and winding.

The performance of the pitch-based carbon fiber that present embodiment makes is as shown in table 1:

The performance test result of the pitch-based carbon fiber that table 1 embodiment 1 makes

Fiber number Specification Strength MPa Modulus GPa Thermal conductivity W/m*K Bulk density g/cm ³ 1 ^# 1K 3435 834 521 2.18

At the same time, in order to verify the performance of the pitch-based carbon fiber prepared by the method of the present invention, the pitch-based carbon fiber obtained by the process of the present invention is compared with the pitch-based carbon fiber obtained by the existing traditional treatment process. The processing parameters and conditions are shown in Table 2. The performance comparison results are shown in Table 3:

Table 2 Treatment Process Comparison

Table 3. Comparison of fiber properties

Fiber number Specification Strength MPa Modulus GPa Thermal conductivity W/m*K Bulk density g/cm ³ 2 ^# 1K 3310 804 502 2.18 1 ^# 1K 3435 833 521 2.18

Example 2

A method for preparing pitch-based carbon fibers with high strength, high thermal conductivity and high modulus, comprising the following steps:

1) Using mesophase pitch as raw material, 2K pitch-based precursors were prepared by melt spinning, and the fiber diameter (average value) was 20 μm.

2) Carry out hot roller drying treatment, the treatment temperature is 150°C, 180°C, 210°C, and the residence time of the fiber in the drying roller is controlled at 600s;

3) Pass through the three rollers for non-melting treatment, the treatment temperature starts at 240°C, ends at 350°C (drawing 1%), the compressed air flow rate is 6m ³ /h, and the residence time of the fiber in the furnace is controlled at 1200s;

4) Carry out low-temperature carbonization treatment through three rollers, the treatment temperature starts at 450°C and ends at 700°C (zone 1 450°C, zone 2, 525°C, zone 3, 600°C, zone 4 650°C, zone 5, 700°C) (drawing-1.5%), under nitrogen protection, the residence time of the fiber in the furnace is controlled at 480s. Medium-temperature carbonization treatment is carried out on three-roll rollers. The treatment temperature starts at 800°C and ends at 1000°C (1st zone 800°C, 2nd zone 850°C, 3rd zone 900°C, 4th zone 950°C, 5th zone, 1000°C) (drawing- 1%), under nitrogen protection, the residence time of the fiber in the furnace is controlled at 480s. High-temperature carbonization treatment is carried out on five-roll rollers. The treatment temperature starts at 1200°C and ends at 1800°C (1200°C for the first zone, 1400°C for the second zone, 1600°C for the third zone, and 1800°C for the fourth zone) (drawing 0.5%), nitrogen protection , The residence time of the fiber in the furnace is controlled at 240s.

5) Pre-graphitization treatment is carried out by passing through five rollers, the treatment temperature is 2200°C (drawing 0.75%), the fiber is protected by argon, and the residence time of the fiber in the furnace is controlled at 180s.

6) Pass five rollers for graphitization treatment, the treatment temperature is 2600°C (drawing 1.5%), and the residence time of the argon-protected fiber in the furnace is controlled at 120s.

7) Go through five rollers for sizing treatment, use epoxy resin-based sizing agent for sizing (the concentration of the sizing solution is 1.5%), control the fiber sizing rate at 1.0% to 3.0%, and then dry, the drying temperature is controlled at 150°C to 200°C ℃; winding and winding. The properties of the prepared pitch-based carbon fiber are shown in Table 4 below:

Table 4 Performance test results of pitch-based carbon fiber

Fiber number Specification Strength MPa Modulus GPa Thermal conductivity W/m*K Bulk density g/cm ³ 3 ^# 2K 3442 831 514 2.18

In summary, the present invention reduces the final temperature of graphitization by re-planning the heat treatment process, introducing hot roller drying, upgrading and optimizing the non-melting process, regrading the carbonization process, and introducing pre-graphitization. When preparing pitch-based graphite fibers with the same thermal conductivity, the graphitization temperature required by the method is lower, which greatly prolongs the life of the graphite heating element and realizes the industrialization of pitch-based graphite fibers with high thermal conductivity.

Claims (10)

1. A preparation method of high-strength, high-thermal-conductivity, high-modulus pitch-based carbon fiber, characterized in that, comprising the following steps: 1) Using mesophase pitch as a raw material, the pitch-based precursor fiber with a fiber diameter of 10 μm to 30 μm is prepared by melt spinning; 2) After the pitch-based raw silk obtained in step 1) is wound and collected, it is sequentially subjected to active unwinding, hot roller drying treatment, non-melting treatment, three-stage carbonization treatment, pre-graphitization treatment, graphitization treatment, and sizing and drying And the final winding and winding to prepare pitch-based carbon fibers with high strength, high thermal conductivity and high modulus. 2. The preparation method of high-strength, high-thermal-conductivity, and high-modulus pitch-based carbon fiber according to claim 1, characterized in that, from the active unwinding operation to the final winding and winding process, the entire line running speed of the equipment operation line is 0.15 m/min～1m/min. 3. The method for preparing high-strength, high-thermal-conductivity, and high-modulus pitch-based carbon fibers according to claim 1, characterized in that, the hot roller drying treatment is at 150°C-220°C for 500s-900s. 4. The method for preparing high-strength, high-thermal-conductivity, and high-modulus pitch-based carbon fibers according to claim 1, wherein the non-melting treatment is carried out at a temperature of 240° C. to 350° C., a draft of 0.1% to 2%, The compressed air flow rate is 0.1m ³ /h to 10m ³ /h, and the processing time is 700s to 2000s. 5. The method for preparing high-strength, high-thermal-conductivity, and high-modulus pitch-based carbon fibers according to claim 1, wherein the three-stage carbonization treatment specifically means that the fibers after infusibility treatment are sequentially subjected to low-temperature carbonization treatment and medium-temperature carbonization treatment and high-temperature carbonization treatment; among them, 5 temperature zones are set during low-temperature carbonization treatment and medium-temperature carbonization treatment; 4 temperature zones are set during high-temperature carbonization treatment. 6. The method for preparing high-strength, high-thermal-conductivity, and high-modulus pitch-based carbon fibers according to claim 5, characterized in that the low-temperature carbonization treatment is carried out at 400°C to 700°C at 400°C to 700°C and stretched at -1% to -2 % under the condition of 200s~500s; medium temperature carbonization treatment is in nitrogen atmosphere, at 800 ℃ ~ 1200 ℃, drafting -1% ~ -2% conditions, treatment 200s ~ 500s; high temperature carbonization treatment is in nitrogen atmosphere Under the atmosphere, under the condition of 1200℃～1800℃, stretching 0.5%～1.5%, process for 200s～400s. 7. The method for preparing high-strength, high-thermal-conductivity, and high-modulus pitch-based carbon fibers according to claim 1, wherein the pre-graphitization treatment is carried out at 2100° C. to 2300° C. and stretched by 0.5% under an argon atmosphere. Under the condition of ~1%, the treatment time is 100s~200s. 8. The method for preparing high-strength, high-thermal-conductivity, and high-modulus pitch-based carbon fibers according to claim 1, wherein the graphitization treatment temperature is at 2600° C. to 2800° C. and stretched by 1% under an argon atmosphere. Under the condition of ~1.5%, treat for 100s ~ 200s. 9. The preparation method of high-strength, high-thermal-conductivity, and high-modulus pitch-based carbon fibers according to claim 1, characterized in that, the sizing and drying process is carried out with an epoxy resin-based sizing agent, and the fiber sizing rate is controlled at 1.0% to 3.0% %; Drying is carried out at 150°C to 200°C. 10. The high-strength, high-thermal conductivity and high-modulus pitch-based carbon fiber prepared by the preparation method according to any one of claims 1 to 9, characterized in that the tensile strength of the high-strength, high-thermal conductivity and high-modulus pitch-based carbon fiber is 3300 MPa above, the modulus is above 800GPa, the thermal conductivity is above 500W/m*K, and the bulk density is above 2.17g/cm ³ .