CN109957969A - A carbon fiber sizing agent, its preparation method, reinforced carbon fiber and carbon fiber composite material - Google Patents

Abstract

It include: modified epoxy, organic solvent, surfactant and water the invention discloses a kind of carbon fiber sizing agent, preparation method, enhancing carbon fiber and carbon fibre composite, the carbon fiber sizing agent；The modified epoxy is to be obtained by polyurethane and acrylic monomer to epoxy resin modification；The polyurethane is to react to obtain with hydroxy polymer by isocyanates.Starching is carried out to carbon fiber using carbon fiber sizing agent prepared by the present invention and obtains enhancing carbon fiber, again will enhancing carbon fiber with resin matrix is compound that carbon fibre composite is made, sizing agent transition zone between the carbon fiber and resin matrix of the carbon fibre composite is able to bear higher impact force and destructive power, therefore the binding force between the carbon fiber and resin matrix in carbon fibre composite increases.

Description

A kind of carbon fiber sizing agent, its preparation method, reinforced carbon fiber and carbon fiber composite Material

technical field

The invention belongs to the technical field of carbon fibers, and in particular relates to a carbon fiber sizing agent, a preparation method thereof, a reinforced carbon fiber and a carbon fiber composite material.

Background technique

Unsaturated resin is an important matrix material for resin-based composite materials. It has the advantages of high strength, good adhesion, heat resistance, chemical resistance, and easy processing. However, the cured product of unsaturated resin has poor adhesion to carbon fiber. , easy to crack, and it is difficult to meet the growing engineering and technical requirements. On the other hand, the surface of carbon fiber is entirely composed of graphitized carbon layers, so the surface activity of carbon fiber is very low. The shear strength between the material layers is very low, and the characteristics of light weight and high strength of carbon fiber itself cannot be exerted. In carbon fiber resin composites, the interface layer between carbon fiber and resin matrix plays an important role in the mechanical properties of the composite material. Good interfacial bonding increases the structural integrity of the composite material, so that the load can be effectively transferred to the carbon fiber through the resin matrix. In order to improve the bonding ability between the carbon fiber and the resin matrix, it is necessary to select a suitable sizing agent to sizing the carbon fiber, and the sizing agent acts as a transition bond between the carbon fiber and the resin matrix. bond between resins.

SUMMARY OF THE INVENTION

The present invention aims to provide a carbon fiber sizing agent capable of increasing the bonding force between carbon fibers and a resin matrix, a preparation method thereof, a reinforced carbon fiber and a carbon fiber composite material.

One aspect of the present invention provides a carbon fiber sizing agent, comprising: modified epoxy resin, organic solvent, surfactant and water; the modified epoxy resin is obtained by modifying epoxy resin with polyurethane and acrylic monomers ; The polyurethane is obtained by reacting isocyanate and hydroxyl polymer; the hydroxyl polymer is at least one of polytetrahydrofuran, polypropylene oxide, polycaprolactone, polylactic acid and polycarbonate.

Another aspect of the present invention provides a preparation method of a carbon fiber sizing agent, comprising:

S1: adding the epoxy resin, isocyanate, hydroxyl polymer, acrylic monomer and solvent in the above-mentioned carbon fiber sizing agent into the stirring tank, and mixing and stirring uniformly to obtain a preform;

S2: adding surfactant and water to the preform prepared in step S1, and stirring evenly to obtain a sizing agent.

Yet another aspect of the present invention provides a reinforced carbon fiber, wherein the reinforced carbon fiber is obtained by sizing the carbon fiber with the above-mentioned carbon fiber sizing agent.

Another aspect of the present invention provides a carbon fiber composite material, the carbon fiber composite material includes a resin matrix and the above-mentioned reinforced carbon fiber.

The present invention adopts modified epoxy resin, organic solvent, surfactant and water to prepare carbon fiber sizing agent, wherein modified epoxy resin refers to the reaction of isocyanate and hydroxyl polymer to obtain polyurethane, and the polyurethane and acrylic monomers together make epoxy resin The modified epoxy resin is obtained by modification. The polyurethane has good elasticity, so using the polyurethane to modify the epoxy resin can increase the toughness of the sizing agent coated on the surface of the carbon fiber, making it less prone to interface cracking; The modification can introduce double bonds in the epoxy resin molecule, thereby increasing the compatibility and bonding force between the epoxy resin and the carbon fiber composite resin matrix. The carbon fiber sizing agent prepared by the present invention is used to sizing carbon fibers to obtain reinforced carbon fibers, and then the reinforced carbon fibers are compounded with a resin matrix to prepare a carbon fiber composite material. The transition layer of the sizing agent between the carbon fibers and the resin matrix of the carbon fiber composite material can withstand higher Therefore, the bonding force between the carbon fiber and the resin matrix in the carbon fiber composite material increases.

Detailed ways

The embodiments of the present invention will be described in detail below. It should be emphasized that the following descriptions are only exemplary, and are not intended to limit the scope and application of the present invention.

The invention provides a carbon fiber sizing agent, comprising: modified epoxy resin, organic solvent, surfactant and water; the modified epoxy resin is obtained by modifying epoxy resin with polyurethane and acrylic monomer; The polyurethane is obtained by reacting isocyanate with a hydroxyl polymer; the hydroxyl polymer is at least one of polytetrahydrofuran, polypropylene oxide, polycaprolactone, polylactic acid and polycarbonate. The present invention adopts isocyanate, hydroxyl polymer and acrylic monomer to modify epoxy resin (first, isocyanate and hydroxyl polymer react to obtain polyurethane, and then polyurethane and acrylic monomer jointly modify epoxy resin), which can increase carbon fiber The compatibility of the epoxy resin in the sizing agent with the resin matrix of the carbon fiber composite material can also increase the toughness of the sizing agent coated on the surface of the carbon fiber, making it less prone to interface cracking.

In the present invention, the hydroxyl polymer is preferably polytetrahydrofuran. Thus, the epoxy resin is modified by using isocyanate, polytetrahydrofuran and acrylic monomer (first, isocyanate and polytetrahydrofuran are reacted to obtain polytetrahydrofuran-type polyurethane, and then polytetrahydrofuran-type polyurethane and acrylic monomer are used to modify the epoxy resin together. It can improve the brittleness of the sizing agent layer under low temperature conditions, thereby ensuring the use effect of the prepared carbon fiber sizing agent under low temperature conditions.

In the present invention, the acrylic monomer is at least one of acrylic acid, methacrylic acid, phenyl-α-acrylic acid and acrylic acid-β-hydroxyethyl ester. Acrylic monomers are used as modifiers for epoxy resins, so that the modified epoxy resin molecules contain double bonds, which can improve different types of resins (ie epoxy resins in sizing agents and matrix resins in carbon fiber composites). ability to combine.

In the present invention, the isocyanate is at least one of toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate and naphthalene 1,5-diisocyanate.

In the present invention, the reaction between the isocyanate and the hydroxyl polymer is carried out under the catalysis of a catalyst; the isocyanate and the hydroxyl polymer are reacted to obtain a polyurethane, and the modification of the epoxy resin by the polyurethane is also carried out under the action of the catalyst. The catalyst is at least one of dibutyltin dilaurate and dibutyltin diacetate.

In the present invention, the epoxy resin is a bisphenol A epoxy resin, and the epoxy equivalent of the bisphenol A epoxy resin is 180-250, and a bisphenol A epoxy resin with a low epoxy equivalent ( That is, the number of active groups in the epoxy resin is large) can increase the probability of chemical bonding between the epoxy resin and the carbon fiber resin matrix, thereby improving the bonding force between the two.

In the present invention, the organic solvent is at least one of xylene, ethyl acetate and butyl acetate.

In the present invention, the surfactant is at least one of Tween 60, Tween 80 and Symbian 20, and the surfactant helps the sizing agent to form an emulsion state and maintain stability.

In the present invention, in terms of weight, the carbon fiber sizing agent comprises: 20-50 parts of modified epoxy resin, 10-30 parts of organic solvent, 3-10 parts of surfactant and 30-50 parts of water.

In the present invention, the solid content of the carbon fiber sizing agent is 20-50%, and the solid content within this range can keep the emulsion formed by the sizing agent in a stable state. precipitation.

The invention provides a preparation method of a carbon fiber sizing agent, comprising:

S1: adding the epoxy resin, isocyanate, hydroxyl polymer, acrylic monomer and solvent in the above-mentioned carbon fiber sizing agent into the stirring tank, and mixing and stirring uniformly to obtain a preform;

S2: adding surfactant and water to the preform prepared in step S1, and stirring evenly to obtain a sizing agent.

In the present invention, the step S1 is preferably adding epoxy resin, isocyanate, hydroxyl polymer, acrylic monomer, catalyst and solvent into a stirring tank, and mixing and stirring uniformly to prepare a preform.

In the present invention, in the step S1, 10-30 parts of epoxy resin, 2-5 parts of isocyanate, 2-5 parts of hydroxyl polymer, 5-10 parts of acrylic monomer, 1-3 parts of catalyst, 10 - 30 parts of solvent, 3-10 parts of surfactant and 30-50 parts of water are added to the stirring tank, and the preform is prepared by mixing and stirring evenly.

In the present invention, in step S2, 3-10 parts of surfactant and 30-50 parts of water are added to the preform prepared in step S1, and the sizing agent is prepared by stirring uniformly.

The present invention provides a reinforced carbon fiber, wherein the reinforced carbon fiber is obtained by sizing the carbon fiber with the above-mentioned carbon fiber sizing agent. Preferably, the carbon fiber can be plasma treated before sizing, thereby increasing the active groups on the surface of the carbon fiber and improving the wettability and bonding force between the carbon fiber and the sizing agent.

The present invention provides a carbon fiber composite material, which comprises a resin matrix and the above-mentioned reinforced carbon fibers. The resin matrix is vinyl resin or unsaturated resin.

The present invention adopts modified epoxy resin, organic solvent, surfactant and water to prepare carbon fiber sizing agent, wherein modified epoxy resin refers to the reaction of isocyanate and hydroxyl polymer to obtain polyurethane, and the polyurethane and acrylic monomers together make epoxy resin The modified epoxy resin is obtained by modification. The polyurethane has good elasticity, so using the polyurethane to modify the epoxy resin can increase the toughness of the sizing agent coated on the surface of the carbon fiber, making it less prone to interface cracking; The modification can introduce double bonds in the epoxy resin molecule, thereby increasing the compatibility and bonding force between the epoxy resin and the carbon fiber composite resin matrix. The carbon fiber sizing agent prepared by the present invention is used to sizing carbon fibers to obtain reinforced carbon fibers, and then the reinforced carbon fibers are compounded with a resin matrix to prepare a carbon fiber composite material. The transition layer of the sizing agent between the carbon fibers and the resin matrix of the carbon fiber composite material can withstand higher Therefore, the bonding force between the carbon fiber and the resin matrix in the carbon fiber composite material increases.

The present invention will be further illustrated by the following examples. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention. The raw materials used in the examples and comparative examples are all obtained from commercial sources, which are not particularly limited in the present invention.

Example 1

By weight, 10 parts of bisphenol A epoxy resin, 5 parts of methacrylic acid, 2.5 parts of toluene diisocyanate, 2.5 parts of polypropylene oxide, 2 parts of dibutyltin dilaurate and 20 parts of xylene were added to the stirred tank , the temperature was controlled at 60 °C, and the preform was prepared by stirring at a constant temperature for 5 h; 3 parts of Tween 60 and 30 parts of distilled water were added to the preform obtained above, and stirred at room temperature for 2 h to obtain a sizing agent (solid content of 33%);

The carbon fibers were sizing with a sizing agent, the sizing speed was 1 m/min, the drying temperature was 120 °C, and the drying time was 1 min to obtain reinforced carbon fibers;

The carbon fiber composite material S1 is prepared by winding the reinforced carbon fiber and the resin matrix.

Example 2

By weight, 20 parts of bisphenol A epoxy resin, 8 parts of methacrylic acid, 3.5 parts of diphenylmethane diisocyanate, 3.5 parts of polycarbonate, 3 parts of dibutyltin dilaurate and 20 parts of ethyl acetate were added to the In the stirring tank, the temperature was controlled at 60 °C, and the preform was stirred at a constant temperature for 5 h to obtain a preform; 5 parts of Tween 60 and 40 parts of distilled water were added to the preform obtained above, and stirred at room temperature for 2 h to obtain a sizing agent. (Solid content is 41%);

The carbon fibers were sizing with a sizing agent, the sizing speed was 1 m/min, the drying temperature was 120 °C, and the drying time was 1 min to obtain reinforced carbon fibers;

The carbon fiber composite material S2 is prepared by winding the reinforced carbon fiber and the resin matrix.

Example 3

By weight, 30 parts of bisphenol A epoxy resin, 8 parts of acrylic acid, 4 parts of hexamethylene diisocyanate, 4 parts of polytetrahydrofuran, 3 parts of dibutyltin dilaurate and 30 parts of xylene were added to the stirring tank, The temperature was controlled at 60°C and stirred at a constant temperature for 5 h to obtain a preform; 5 parts of Tween 80 and 40 parts of distilled water were added to the preform obtained above, and stirred at room temperature for 2 h to obtain a sizing agent (solid content of 43%);

The carbon fibers were sizing with a sizing agent, the sizing speed was 1 m/min, the drying temperature was 120 °C, and the drying time was 1 min to obtain reinforced carbon fibers;

The carbon fiber composite material S3 is prepared by winding the reinforced carbon fiber and the resin matrix.

Example 4

By weight, 30 parts of bisphenol A epoxy resin, 10 parts of β-hydroxyethyl acrylate, 4.5 parts of xylylene diisocyanate, 4.5 parts of polytetrahydrofuran, 3 parts of dibutyltin diacetate, and 30 parts of xylene are combined The preform was prepared by adding 8 parts of Tween 80 and 50 parts of distilled water to the preform prepared above, and stirred at room temperature for 2 h to obtain the preform. Sizing agent (42% solid content);

The carbon fibers were sizing with a sizing agent, the sizing speed was 1 m/min, the drying temperature was 120 °C, and the drying time was 1 min to obtain reinforced carbon fibers;

The carbon fiber composite material S4 is prepared by winding the reinforced carbon fiber and the resin matrix.

Example 5

By weight, 30 parts of bisphenol A epoxy resin, 8 parts of phenyl-alpha-acrylic acid, 5 parts of naphthalene 1,5-diisocyanate, 5 parts of polylactic acid, 3 parts of dibutyltin diacetate and 30 parts of butyl acetate are combined The preform was prepared by adding 10 parts of Saipan 20 and 50 parts of distilled water to the preform obtained above, and stirring at room temperature for 2 h to obtain the preform. Sizing agent (43% solid content);

The carbon fibers were sizing with a sizing agent, the sizing speed was 1 m/min, the drying temperature was 120 °C, and the drying time was 1 min to obtain reinforced carbon fibers;

The carbon fiber composite material S5 is prepared by winding the reinforced carbon fiber and the resin matrix.

Example 6

By weight, 30 parts of bisphenol A epoxy resin, 8 parts of acrylic acid, 4 parts of toluene diisocyanate, 4 parts of polycaprolactone, 3 parts of dibutyltin dilaurate and 30 parts of xylene were added to the stirring tank, and the temperature was Control the temperature at 60 °C, stir at a constant temperature for 5 h to obtain a preform; add 5 parts of Tween 80 and 40 parts of distilled water to the preform obtained above, and stir at room temperature for 2 h to obtain a sizing agent (solid content of 43 %);

The carbon fibers were sizing with a sizing agent, the sizing speed was 1 m/min, the drying temperature was 120 °C, and the drying time was 1 min to obtain reinforced carbon fibers;

The carbon fiber composite material S6 is prepared by winding the reinforced carbon fiber and the resin matrix.

Comparative Example 1

By weight, 20 parts of bisphenol A epoxy resin and 20 parts of xylene were added to the stirring tank, the temperature was controlled at 60 °C, and the temperature was stirred for 5 h to prepare a preform; to the preform prepared above, 3 parts of Tween 60 and 30 parts of distilled water, and stirred at room temperature for 2 h to prepare a sizing agent (solid content of 31%);

The carbon fibers were sizing with a sizing agent, the sizing speed was 1 m/min, the drying temperature was 120 °C, and the drying time was 1 min to obtain reinforced carbon fibers;

The carbon fiber composite material D1 is prepared by winding the reinforced carbon fiber and the resin matrix.

Comparative Example 2

By weight, 20 parts of bisphenol A epoxy resin, 3.5 parts of diphenylmethane diisocyanate, 3.5 parts of polytetrahydrofuran, 3 parts of dibutyltin diacetate and 20 parts of xylene were added to the stirring tank, and the temperature was controlled at 60 ° C , stirred at a constant temperature for 5 h to obtain a preform; 5 parts of Tween 60 and 40 parts of distilled water were added to the preform obtained above, and stirred at room temperature for 2 h to obtain a sizing agent (solid content of 36%);

The carbon fibers were sizing with a sizing agent, the sizing speed was 1 m/min, the drying temperature was 120 °C, and the drying time was 1 min to obtain reinforced carbon fibers;

The carbon fiber composite material D2 is prepared by winding the reinforced carbon fiber and the resin matrix.

Comparative Example 3

By weight, 20 parts of bisphenol A epoxy resin, 8 parts of acrylic acid, 3 parts of dibutyltin diacetate and 20 parts of xylene were added to the stirring kettle, the temperature was controlled at 60°C, and the preform was prepared by stirring at a constant temperature for 5 h. 5 parts of Tween 80 and 40 parts of distilled water were added to the preform obtained above, and stirred for 2 h at room temperature to obtain a sizing agent (solid content of 37%);

The carbon fibers were sizing with a sizing agent, the sizing speed was 1 m/min, the drying temperature was 120 °C, and the drying time was 1 min to obtain reinforced carbon fibers;

The carbon fiber composite material D3 is prepared by winding the reinforced carbon fiber and the resin matrix.

Performance Testing

1. Fiber appearance test: use the visual method to observe whether there are filaments or broken fibers on the surface of carbon fiber;

2. Interlaminar shear test: GB/T 1450.1-2005 is used to test the bonding ability between fiber and resin.

The test results are shown in Table 1.

Table 1

sample Exterior interlaminar shear strength S1 Good, no hair breakage 65MPa S2 Good, no hair breakage 63MPa S3 Good, no hair breakage 68MPa S4 Good, no hair breakage 67MPa S5 Good, no hair breakage 63MPa S6 Good, no hair breakage 64MPa D1 Good, no hair breakage 42MPa D2 Good, no hair breakage 55MPa D3 Good, no hair breakage 48MPa

As can be seen from the test results in Table 1: the carbon fiber sizing agent of the present invention is used to sizing carbon fibers to prepare reinforced carbon fibers, and the reinforced carbon fibers are entangled with the resin matrix to prepare carbon fiber composite materials S1-S6, and the appearance of the prepared carbon fiber composite material samples S1-S6 Good, there is no phenomenon of broken wires and hairs, and the interlaminar peel strengths of carbon fiber composite materials S1-S6 are all greater than 60 MPa. Comparative Examples 1, 2 and 3 do not use the carbon fiber sizing agent of the present invention (Comparative Example 1 does not modify epoxy resin, Comparative Example 2 uses polyurethane to modify epoxy resin, and Comparative Example 3 uses acrylic monomer to modify epoxy resin. It can be seen from the test results that the interlaminar peel strength of the carbon fiber composite D1 prepared by the sizing agent without epoxy resin modification is at least 42MPa, and only polyurethane is used to modify epoxy resin or only acrylic acid is used. The interlaminar peel strengths of carbon fiber composites D2 and D3 prepared from epoxy resin-modified sizing agents were also lower, specifically 55 MPa and 48 MPa. That is to say, the use of the carbon fiber sizing agent of the present invention can significantly increase the bonding force between the carbon fibers in the carbon fiber composite material and the resin matrix.

Although the embodiments of the present invention have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Embodiments are subject to variations, modifications, substitutions and variations.

Claims (10)

1. a kind of carbon fiber sizing agent characterized by comprising modified epoxy, organic solvent, surfactant and water； The modified epoxy is to be obtained by polyurethane and acrylic monomer to epoxy resin modification；The polyurethane is by isocyanide Acid esters reacts to obtain with hydroxy polymer；The hydroxy polymer is polytetrahydrofuran, polypropylene oxide, polycaprolactone, poly- cream At least one of acid and polycarbonate.

2. carbon fiber sizing agent according to claim 1, which is characterized in that the acrylic monomer is acrylic acid, first At least one of base acrylic acid, phenyl-alpha-acrylic and senecioate-hydroxyl ethyl ester.

3. carbon fiber sizing agent according to claim 1, which is characterized in that the isocyanates is toluene diisocynate Ester, methyl diphenylene diisocyanate, bis- isocyanide of hexamethylene diisocyanate, benzene dimethylene diisocyanate and naphthalene 1,5- At least one of acid esters.

4. carbon fiber sizing agent according to claim 1, which is characterized in that the epoxy resin is bisphenol type epoxy tree Rouge；The epoxide equivalent of the bisphenol A type epoxy resin is 180-250；The organic solvent is dimethylbenzene, ethyl acetate and acetic acid At least one of butyl ester；The surfactant is at least one of polysorbate60, Tween 80 and Saipan 20.

5. carbon fiber sizing agent described in any one of -4 according to claim 1, which is characterized in that by weight, the carbon fiber Tieing up sizing agent includes: 20-50 parts of modified epoxies, 10-30 parts of organic solvents, 3-10 parts of surfactants and 30-50 parts of water.

6. carbon fiber sizing agent according to claim 5, which is characterized in that the solid content of the carbon fiber sizing agent is 20-50%。

7. a kind of preparation method of carbon fiber sizing agent characterized by comprising

S1: by epoxy resin, isocyanates, the hydroxyl polymeric in carbon fiber sizing agent of any of claims 1-6 Stirred tank is added in object, acrylic monomers and solvent, and obtained precast body is mixed evenly；

S2: surfactant and water are added in the precast body of step S1 preparation, stirs evenly obtained sizing agent.

8. a kind of enhancing carbon fiber, which is characterized in that the enhancing carbon fiber is using of any of claims 1-6 described Carbon fiber sizing agent carries out starching to carbon fiber and forms.

9. a kind of carbon fibre composite, which is characterized in that the carbon fibre composite includes resin matrix and claim 8 The enhancing carbon fiber.

10. carbon fibre composite according to claim 9, which is characterized in that the resin matrix is vinylite Or unsaturated-resin.