Impregnating glue solution for testing tensile property of carbon fiber multifilament and application method of impregnating glue solution

Abstract

The invention provides a dipping glue solution for testing the tensile property of a carbon fiber multifilament. The dipping glue solution comprises the following components in parts by mass: 100 parts of epoxy resin and 23-32 parts of a curing agent. By reducing the viscosity of the epoxy resin, the epoxy resin glue solution and the carbon fiber multifilament can be fully infiltrated without an organic solvent, and the problem of occupational hazards caused by volatilization of a large amount of organic solvent in the carbon fiber sample preparation and curing process is solved; and meanwhile, the problem that the humidity of a laboratory cannot meet the method requirement due to the fact that southern enterprises start air exhaust in rainy seasons is solved. By optimizing the formula of the dipping glue solution, the tensile sample strip with a smooth appearance is prepared and can be used for tensile property sample preparation of various polyacrylonitrile-based carbon fibers.

Description

Technical Field

[0001] This invention belongs to the field of carbon fiber sample preparation technology, specifically relating to an impregnation solution for testing the tensile properties of carbon fiber multifilaments and its application method. Background Technology

[0002] Carbon fiber is a new type of high-strength fiber material with a carbon content of over 95%. It has excellent mechanical properties, a specific gravity of less than one-quarter that of steel, but a strength 7-8 times that of steel. It also has corrosion resistance and has broad application prospects in the future.

[0003] The booming development of China's carbon fiber industry has driven advancements in carbon fiber testing technology. The main mechanical properties of carbon fiber include tensile strength, tensile modulus of elasticity, and elongation at break. Currently, the main testing methods for carbon fiber mechanical properties include Chinese GB / T 3362, American ASTM D4018, and Japanese JIS K7073, all of which involve resin impregnation pretreatment of the carbon fiber to be tested.

[0004] The national standard GB / T 3362 clearly specifies and describes the types of epoxy resins, curing agents, resin content, and curing conditions. To obtain multifilament tensile specimens with an appropriate resin content, this method requires adjusting the concentration of the impregnation solution with a solvent.

[0005] Currently, toxic solvents such as acetone and tetrahydrofuran are often used in the production of carbon fiber reinforced composite materials and the testing of the mechanical properties of multifilaments, which directly endanger the occupational health of production and testing personnel.

[0006] CN103981715A discloses a solvent-free adhesive for testing the tensile properties of carbon fiber multifilaments, comprising 100 parts epoxy resin; 50-300 parts curing agent; 0.5-100 parts reactive diluent; and 0.5-5 parts accelerator. The reactive diluent is selected from at least one of butanediol diglycidyl ether, polyethanol diglycidyl ether, and polypropylene glycol diglycidyl ether. While this patent avoids the use of highly toxic organic solvents such as acetone and tetrahydrofuran, the use of ether-based reactive diluents still poses some risk to operators; furthermore, ethers are volatile, resulting in a short workability time for the formed solvent-free adhesive.

[0007] In summary, how to achieve full impregnation of epoxy resin adhesive with carbon fiber multifilament without relying on toxic solvents and harmful reactive diluents, while ensuring the safety and efficiency of the production and testing process, is an urgent problem to be solved. Summary of the Invention

[0008] The purpose of this invention is to provide an impregnation solution for testing the tensile properties of carbon fiber multifilaments. This solution achieves thorough wetting of the carbon fiber multifilaments with epoxy resin without relying on toxic solvents or harmful reactive diluents, while ensuring the safety and efficiency of the production and testing process. It solves the occupational hazard problem caused by the volatilization of large amounts of organic solvents during carbon fiber sample preparation and curing, and also addresses the issue of insufficient laboratory humidity in southern enterprises during the rainy season due to ventilation. The impregnation solution for testing the tensile properties of carbon fiber multifilaments described in this invention comprises the following components in parts by weight:

[0009] 100 parts epoxy resin;

[0010] 23-32 parts of curing agent;

[0011] The epoxy resin used is EPOLAM 2040 Resin, and the curing agent used is EPOLAM 2047 Hardener.

[0012] Furthermore, the viscosity of the impregnation solution for testing the tensile properties of carbon fiber multifilament, as described above, is 0.1–0.2 Pa·s at 25°C.

[0013] The application method of the impregnating adhesive solution in the tensile property testing of carbon fiber multifilament, as described above, includes the following steps:

[0014] (a) Add a curing agent to an epoxy resin and stir for at least 2 minutes to obtain the impregnation solution;

[0015] (b) Immerse the carbon fiber multifilament in the impregnation solution obtained in step (a) for 1 to 15 minutes, then perform a scraping process, and place the treated carbon fiber multifilament in a forced-air oven for curing.

[0016] Furthermore, in the application method of the impregnation solution in the tensile performance test of carbon fiber multifilament as described above, the curing process in step (b) can be selected as step curing or constant temperature curing. Step curing specifically includes: first step curing temperature 50-70℃, curing time 0.5 hours, second step curing temperature 120℃, curing time 2 hours; constant temperature curing specifically includes curing temperature 120℃, curing time 2 hours.

[0017] Furthermore, in the application method of the impregnation solution in the tensile performance test of carbon fiber multifilament as described above, the impregnation solution, after preparation, has an operable time of 60 minutes or more for impregnating carbon fiber multifilament at a temperature of 23±2℃ and a humidity of ≤50%RH.

[0018] Furthermore, in the application method of the impregnation solution in the tensile property test of carbon fiber multifilament as described above, the carbon fiber multifilament is one of 3K, 12K, 24K, and 48K.

[0019] Furthermore, in the application method of the impregnation solution in the tensile performance testing of carbon fiber multifilaments as described above, the carbon fiber multifilament samples prepared by the impregnation solution are subjected to tensile performance testing, and the discrete values ​​of the tensile strength test are all less than 4%, and the discrete values ​​of the tensile elastic modulus test are all less than 2%.

[0020] Without violating common sense in the field, the above-described implementation conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] (1) This invention uses epoxy resin and amine curing agent with low viscosity, without the need to add organic solvents and active diluents, which can achieve full impregnation of epoxy resin liquid with carbon fiber multifilament, solves the occupational hazard problem caused by the volatilization of a large amount of organic solvents during carbon fiber sample preparation and curing, and also solves the problem that the laboratory humidity in southern enterprises does not meet the method requirements due to the opening of exhaust ventilation during the rainy season.

[0023] (2) This invention optimizes the adhesive formulation to prepare smooth tensile specimens, which can be used for tensile property testing of various polyacrylonitrile-based carbon fibers. The tensile test results are comparable to those of tensile specimens prepared by impregnation with the adhesive recommended in method GB / T 3362, with smaller dispersion values ​​and less influence from environmental humidity.

[0024] (3) The impregnation solution of this invention has good wettability and environmental friendliness. The constant temperature curing process helps to reduce curing time and ensure the strength of carbon fibers. This impregnation solution has important prospects for widespread application in the research and production of fiber-reinforced composite materials.

[0025] (4) The impregnation solution of the present invention can be used for impregnating carbon fiber multifilaments for 60 minutes or more at a temperature of 23±2℃ and a humidity of ≤50%RH. This feature significantly reduces the necessity of frequently preparing the impregnation solution during the test, avoids the tediousness of preparing and using it immediately, and greatly improves the convenience of the overall operation and the efficiency of the test. Detailed Implementation

[0026] The present invention will be described below through specific embodiments, but the present invention is not limited to the following embodiments.

[0027] Tensile properties were tested according to the specifications in GB / T 3362. In the examples, the epoxy resin was EPOLAM 2040 Resin from XSON Ltd., and the curing agent was EPOLAM 2047 Hardener from XSON Ltd. EPOLAM 2040 Resin's main component is a mixture of a polymer of 4,4'-(1-methylethylidene)bisphenol and (chloromethyl)ethylene oxide with 2,2'-[1,4-butadiene di(oxomethylene)]di-ethylene oxide; EPOLAM 2047 Hardener's main component is a mixture of polyoxypropylene diamine and 5-amino-1,3,3-trimethylcyclohexylamine.

[0028] Example 1

[0029] The impregnation solution for testing the tensile properties of carbon fiber multifilaments according to the present invention comprises the following components in parts by weight:

[0030] 100 parts epoxy resin;

[0031] 32 parts of curing agent;

[0032] The application method of the above-mentioned impregnation solution in the tensile property testing of carbon fiber multifilament includes the following steps:

[0033] (a) Add curing agent to epoxy resin and stir for 2 minutes to obtain impregnation solution;

[0034] (b) Immerse the 3K carbon fiber multifilament produced by Shanghai Petrochemical into the impregnation solution obtained in step (a) for 1 minute; after scraping off the adhesive, place it in a forced-air oven for curing. The curing process conditions are as follows: curing temperature 120℃, curing time 2 hours.

[0035] Finally, tensile specimens were prepared, and the tensile properties of carbon fiber multifilaments are shown in Table 2.

[0036] Example 2

[0037] The impregnation solution for testing the tensile properties of carbon fiber multifilaments according to the present invention comprises the following components in parts by weight:

[0038] 100 parts epoxy resin;

[0039] 32 parts of curing agent;

[0040] The application method of the above-mentioned impregnation solution in the tensile property testing of carbon fiber multifilament includes the following steps:

[0041] (a) Add curing agent to epoxy resin and stir for 2 minutes to obtain impregnation solution;

[0042] (b) Immerse the 12K carbon fiber multifilament produced by Shanghai Petrochemical into the impregnation solution obtained in step (a) for 1 minute; after scraping off the adhesive, place it in a forced-air oven for curing. The curing process conditions are as follows: curing temperature 120℃, curing time 2 hours.

[0043] Finally, tensile specimens were prepared, and the tensile properties of carbon fiber multifilaments are shown in Table 2.

[0044] Example 3

[0045] The impregnation solution for testing the tensile properties of carbon fiber multifilaments according to the present invention comprises the following components in parts by weight:

[0046] 100 parts epoxy resin;

[0047] 32 parts of curing agent;

[0048] The application method of the above-mentioned impregnation solution in the tensile property testing of carbon fiber multifilament includes the following steps:

[0049] (a) Add curing agent to epoxy resin and stir for 2 minutes to obtain impregnation solution;

[0050] (b) Immerse the 24K carbon fiber multifilament produced by Shanghai Petrochemical into the impregnation solution obtained in step (a) for 1 minute; after scraping off the adhesive, place it in a forced-air oven for curing. The curing process conditions are as follows: curing temperature 120℃, curing time 2 hours.

[0051] Finally, tensile specimens were prepared, and the tensile properties of carbon fiber multifilaments are shown in Table 2.

[0052] Example 4

[0053] The impregnation solution for testing the tensile properties of carbon fiber multifilaments according to the present invention comprises the following components in parts by weight:

[0054] 100 parts epoxy resin;

[0055] 32 parts of curing agent;

[0056] The application method of the above-mentioned impregnation solution in the tensile property testing of carbon fiber multifilament includes the following steps:

[0057] (a) Add curing agent to epoxy resin and stir for 2 minutes to obtain impregnation solution;

[0058] (b) Immerse the 48K carbon fiber multifilament produced by Shanghai Petrochemical into the impregnation solution obtained in step (a) for 1 minute; after scraping off the adhesive, place it in a forced-air oven for curing. The curing process conditions are as follows: curing temperature 120℃, curing time 2 hours.

[0059] Finally, tensile specimens were prepared, and the tensile properties of carbon fiber multifilaments are shown in Table 2.

[0060] Example 5

[0061] The impregnation solution for testing the tensile properties of carbon fiber multifilaments according to the present invention comprises the following components in parts by weight:

[0062] 100 parts epoxy resin;

[0063] 23 parts curing agent;

[0064] The application method of the above-mentioned impregnation solution in the tensile property testing of carbon fiber multifilament includes the following steps:

[0065] (a) Add curing agent to epoxy resin and stir for 2 minutes to obtain impregnation solution;

[0066] (b) Immerse the 48K carbon fiber multifilament produced by Shanghai Petrochemical into the impregnation solution obtained in step (a) for 1 minute; after scraping off the adhesive, place it in a forced-air oven for curing. The curing process conditions are as follows: curing temperature 120℃, curing time 2 hours.

[0067] Finally, tensile specimens were prepared, and the tensile properties of carbon fiber multifilaments are shown in Table 2.

[0068] Example 6

[0069] The impregnation solution for testing the tensile properties of carbon fiber multifilaments according to the present invention comprises the following components in parts by weight:

[0070] 100 parts epoxy resin;

[0071] 28 parts of curing agent;

[0072] The application method of the above-mentioned impregnation solution in the tensile property testing of carbon fiber multifilament includes the following steps:

[0073] (a) Add curing agent to epoxy resin and stir for 2 minutes to obtain impregnation solution;

[0074] (b) Immerse the 48K carbon fiber multifilament produced by Shanghai Petrochemical into the impregnation solution obtained in step (a) for 1 minute; after scraping off the adhesive, place it in a forced-air oven for curing. The curing process conditions are as follows: curing temperature 120℃, curing time 2 hours.

[0075] Finally, tensile specimens were prepared, and the tensile properties of carbon fiber multifilaments are shown in Table 2.

[0076] Example 7

[0077] The impregnation solution for testing the tensile properties of carbon fiber multifilaments according to the present invention comprises the following components in parts by weight:

[0078] 100 parts epoxy resin;

[0079] 32 parts of curing agent;

[0080] The application method of the above-mentioned impregnation solution in the tensile property testing of carbon fiber multifilament includes the following steps:

[0081] (a) Add curing agent to epoxy resin and stir for 2 minutes to obtain impregnation solution;

[0082] (b) Place the impregnation solution obtained in step (a) in an environment with a temperature of 23±2℃ and a humidity of ≤50%RH for 60 minutes;

[0083] (c) Immerse the 48K carbon fiber multifilament produced by Shanghai Petrochemical into the impregnation solution obtained in step (b) for 1 minute; after scraping off the adhesive, place it in a forced-air oven for curing. The curing process conditions are as follows: curing temperature 120℃, curing time 2 hours.

[0084] Finally, tensile specimens were prepared, and the tensile properties of carbon fiber multifilaments are shown in Table 2.

[0085] Example 8

[0086] The impregnation solution for testing the tensile properties of carbon fiber multifilaments according to the present invention comprises the following components in parts by weight:

[0087] 100 parts epoxy resin;

[0088] 32 parts of curing agent;

[0089] The application method of the above-mentioned impregnation solution in the tensile property testing of carbon fiber multifilament includes the following steps:

[0090] (a) Add curing agent to epoxy resin and stir for 2 minutes to obtain impregnation solution;

[0091] (b) Immerse the 48K carbon fiber multifilament produced by Shanghai Petrochemical into the impregnation solution obtained in step (a) for 1 minute; after scraping off the adhesive, place it in a forced-air oven for curing. The curing process conditions are as follows: first step curing temperature 60℃, curing time 0.5 hours, second step curing temperature 120℃, curing time 2 hours.

[0092] Finally, tensile specimens were prepared, and the tensile properties of carbon fiber multifilaments are shown in Table 2.

[0093] The impregnation and curing methods of carbon fiber multifilaments in Examples 1-8 are shown in Table 1.

[0094] Table 1. Impregnation and curing methods for carbon fiber multifilaments

[0095]

[0096] Comparative Example 1

[0097] The tensile test results of the tensile specimens prepared by Shanghai Petrochemical using the impregnation solution recommended in GB / T 3362 for the production of 3K carbon fiber multifilament are shown in Table 2.

[0098] Comparative Example 2

[0099] The tensile test results of the tensile specimens prepared by Shanghai Petrochemical using the impregnation solution recommended in GB / T 3362 for the production of 12K carbon fiber multifilament are shown in Table 2.

[0100] Comparative Example 3

[0101] The tensile test results of the tensile specimens prepared by Shanghai Petrochemical using the impregnation solution recommended in GB / T 3362 for the production of 24K carbon fiber multifilament are shown in Table 2.

[0102] Comparative Example 4

[0103] The tensile test results of the 48K carbon fiber multifilament produced by Shanghai Petrochemical using the impregnation solution recommended in GB / T 3362 are shown in Table 2.

[0104] Table 2 Tensile properties of carbon fiber multifilament

[0105]

[0106] The tensile modulus of elasticity was measured using a contact extensometer.

[0107] Elongation at break = Tensile strength / Tensile modulus.

[0108] A comparison of Example 1 and Comparative Example 1 shows that the tensile strength, tensile modulus, and elongation of the 3K carbon fiber multifilament prepared using the impregnation solution described in this invention are comparable to those of the 3K carbon fiber multifilament prepared using the impregnation solution recommended in method GB / T 3362. A comparison of Example 2 and Comparative Example 2 shows that the tensile strength, tensile modulus, and elongation of the 12K carbon fiber multifilament prepared using the impregnation solution described in this invention are comparable to those of the 12K carbon fiber multifilament prepared using the impregnation solution recommended in method GB / T 3362. A comparison of Example 3 and Comparative Example 3 shows that the tensile strength, tensile modulus, and elongation of the 24K carbon fiber multifilament prepared using the impregnation solution described in this invention are comparable to those of the 24K carbon fiber multifilament prepared using the impregnation solution recommended in method GB / T 3362. A comparison of Examples 4-8 and Comparative Example 4 shows that the tensile strength, tensile modulus, and elongation of the 48K carbon fiber multifilaments prepared using the impregnation solution described in this invention are comparable to those of the 48K carbon fiber multifilaments prepared using the impregnation solution recommended in method GB / T 3362. Furthermore, the dispersion values ​​of all tensile strength tests and the dispersion values ​​of all tensile modulus tests for the carbon fiber multifilament samples prepared using the impregnation solution described in this invention are less than 4%, fully demonstrating the effectiveness of this invention.

Claims

1. An impregnation solution for testing the tensile properties of carbon fiber multifilaments, characterized in that: The impregnation solution contains the following components in parts by weight: 100 parts epoxy resin; 23-32 parts of curing agent; The epoxy resin used is EPOLAM 2040 Resin. The curing agent used is EPOLAM 2047 Hardener.

2. The impregnation solution for testing the tensile properties of carbon fiber multifilament according to claim 1, characterized in that: The viscosity of the impregnating adhesive solution at 25°C is 0.1–0.2 Pa·s.

3. A method for applying the impregnation solution as described in claim 1 or 2 to the tensile property testing of carbon fiber multifilament, characterized in that: The method includes the following steps: (a) Add a curing agent to an epoxy resin and stir for at least 2 minutes to obtain the impregnation solution; (b) Immerse the carbon fiber multifilament in the impregnation solution obtained in step (a) for 1 to 15 minutes, then perform a scraping process, and place the treated carbon fiber multifilament in a forced-air oven for curing.

4. The method for applying the impregnation solution according to claim 3 in the tensile property testing of carbon fiber multifilament, characterized in that: The curing process described in step (b) can be either stepped curing or constant temperature curing. Stepped curing specifically involves: first step curing temperature of 50-70℃ and curing time of 0.5 hours, and second step curing temperature of 120℃ and curing time of 2 hours. The constant temperature curing process specifically involves a curing temperature of 120℃ and a curing time of 2 hours.

5. The method for applying the impregnation solution according to claim 3 in the tensile property testing of carbon fiber multifilament, characterized in that: The impregnation solution, after preparation, can be used for impregnating carbon fiber multifilaments at a temperature of 23±2℃ and a humidity of ≤50%RH for 60 minutes or more.

6. The method for applying the impregnation solution according to claim 3 in the tensile property testing of carbon fiber multifilament, characterized in that: The carbon fiber multifilament is one of 3K, 12K, 24K or 48K.

7. The method for applying the impregnation solution according to claim 3 in the tensile property testing of carbon fiber multifilament, characterized in that: The carbon fiber multifilament strips prepared by the impregnation solution according to claim 1 or 2 are subjected to tensile property tests, and the discrete values ​​of the tensile strength test are all less than 4%, and the discrete values ​​of the tensile elastic modulus test are all less than 2%.

8. The method for applying the impregnation solution according to claim 3 in the tensile property testing of carbon fiber multifilament, characterized in that: The curing process described in step (b) can be either stepped curing or constant temperature curing. Stepped curing specifically involves: first step curing temperature of 50-70℃ and curing time of 0.5 hours, and second step curing temperature of 120℃ and curing time of 2 hours. The constant temperature curing is specifically a curing temperature of 120℃ and a curing time of 2 hours; the carbon fiber multifilament is one of 3K, 12K, 24K or 48K.

9. The method for applying the impregnation solution according to claim 8 in the tensile property testing of carbon fiber multifilament, characterized in that: The impregnation time in step (b) is 1 minute; the working time for impregnating carbon fiber multifilaments after the impregnation solution is prepared is 60 minutes or more at a temperature of 23±2℃ and a humidity of ≤50%RH.

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