A sizing agent based on modified chlorinated polypropylene and its preparation method

Abstract

The present invention relates to a thermoplastic sizing agent for carbon fiber reinforced polypropylene composites, and particularly relates to a sizing agent based on modified chlorinated polypropylene and a preparation method thereof. The modified chlorinated polypropylene is dissolved to obtain an organic solution, the compound emulsifier is dissolved in water to obtain an aqueous solution, and the aqueous solution is dropped into the organic solution for emulsifying and stirring to obtain the sizing agent; the compound emulsifier is sulfonated castor oil and sodium dodecyl sulfate, and the addition amount of the compound emulsifier is 60-80% of the mass of the modified chlorinated polypropylene; the process of the emulsifying and stirring is as follows: first, low-speed stirring is carried out for 40-70 minutes, and then high-speed stirring is carried out for 20-30 minutes. The sizing agent based on modified chlorinated polypropylene prepared by the present invention has better emulsion stability, thereby increasing the storage time of the emulsion preparation, increasing its service life, and improving the efficiency of the sizing agent in the preparation process of carbon fiber reinforced polypropylene composites.

Description

Technical Field

[0001] The present invention relates to a thermoplastic sizing agent for carbon fiber reinforced polypropylene composites, and specifically relates to a sizing agent based on modified chlorinated polypropylene and a preparation method thereof. Background Art

[0002] Disclosing the information of this background art section is only intended to enhance the overall understanding of the present invention, and it is not necessarily regarded as an admission or any form of implication that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] Carbon fiber reinforced polypropylene composite is a carbon fiber reinforced thermoplastic resin composite, which has the advantages of good mechanical properties, fatigue resistance, high temperature resistance, short molding cycle, easy recycling and reuse, etc., and can be widely used in the fields such as automotive component production. At present, most of the carbon fibers sold on the market are coated with a thermosetting sizing agent that matches thermosetting epoxy resin. If this sizing agent is directly used for carbon fibers and thermoplastic resin matrix, it will lead to poor wettability between the above-mentioned carbon fibers and thermoplastic resin matrix, and further affect the interfacial shear strength of thermoplastic composites.

[0004] According to the research and understanding of the inventor, there are few sizing agents currently used for carbon fiber reinforced thermoplastic resin composites. Among them, modified chlorinated polypropylene produced by copolymerization of acrylate monomers and chlorinated polypropylene can be used as a sizing agent for carbon fiber reinforced polypropylene composites. However, according to the further research of the inventor, modified chlorinated polypropylene needs to be made into an emulsion for specific applications, and the emulsion made of modified chlorinated polypropylene has the defect of poor stability and cannot be stored for a long time; if it is prepared and used immediately, it will make the steps cumbersome and the efficiency low. Summary of the Invention

[0005] In order to solve the deficiencies of the prior art, the purpose of the present invention is to provide a sizing agent based on modified chlorinated polypropylene and a preparation method thereof. The sizing agent based on modified chlorinated polypropylene prepared by the present invention has better emulsion stability, thereby increasing the storage time of the emulsion preparation, increasing its service life, and improving the efficiency of the sizing agent in the preparation process of carbon fiber reinforced polypropylene composites.

[0006] In order to achieve the above purpose, the technical solution of the present invention is as follows:

[0007] On the one hand, a preparation method of a sizing agent based on modified chlorinated polypropylene, which is obtained by dissolving modified chlorinated polypropylene to obtain an organic solution, dissolving a compound emulsifier in water to obtain an aqueous solution, and dropping the aqueous solution into the organic solution and performing emulsifying stirring.

[0008] The modified chlorinated polypropylene is obtained by a polymerization reaction of chlorinated polypropylene with methyl methacrylate, butyl acrylate, acrylic acid, and isobornyl methacrylate.

[0009] The compound emulsifier is sulfonated castor oil and sodium dodecyl sulfate, and the addition amount of the compound emulsifier is 60-80% of the mass of the modified chlorinated polypropylene;

[0010] The process of emulsifying and stirring is as follows: first, stir at a low speed for 40-70 min, and then stir at a high speed for 20-30 min. The stirring rate of the low-speed stirring is 500-800 rpm, and the stirring rate of the high-speed stirring is 8000-12000 rpm.

[0011] The research of the present invention finds that since the modified chlorinated polypropylene is obtained by the polymerization reaction of chlorinated polypropylene with methyl methacrylate, butyl acrylate, acrylic acid, and isobornyl methacrylate, there are many units in its polymer chain. The emulsifier used usually needs to be compounded with multiple components, and the amount of emulsifier used is large, resulting in poor stability of the formed emulsion. The present invention uses sulfonated castor oil and sodium dodecyl sulfate as the compound emulsifier. The HLB value of sulfonated castor oil is 30.98, and the HLB value of sodium dodecyl sulfate is 40. According to the mixing additivity of the HLB value: HLB=(HLBa Wa+HLBb / Wb) / (Wa+Wb), ensure that the amount of the compound emulsifier is 60-80% of the mass of the modified chlorinated polypropylene, realize the stable emulsification of the non-ionic and anionic compound emulsifier, reduce the amount of emulsifier and external components, and thus reduce the influence on the sizing agent emulsion system; at the same time, in the present invention, stirring at a low speed first and then at a high speed can enable the water-oil system in the emulsification process to undergo an inversion, and the water-oil components can be transformed step by step, avoiding the demulsification caused by the instantaneous destruction of the water-oil system balance during high-speed stirring, improving the emulsion stability and the uniformity of particle size dispersion, thereby increasing the storage time of the emulsion and increasing its service life.

[0012] In further research, it is found that when adding a neutralizing agent to the organic solvent and mixing evenly first, then dropping the aqueous solution, and then carrying out emulsifying and stirring, it is beneficial to improve the interlaminar shear strength of the carbon fiber reinforced polypropylene composite material, thereby improving the performance of the composite material, and at the same time, it can also avoid the reduction of emulsion stability.

[0013] On the other hand, a sizing agent based on modified chlorinated polypropylene is obtained by the above preparation method.

[0014] On the third hand, an application of the above sizing agent based on modified chlorinated polypropylene in the preparation of carbon fiber reinforced polypropylene composite materials.

[0015] The beneficial effects of the present invention are as follows:

[0016] 1. In the preparation method of the sizing agent based on modified chlorinated polypropylene of the present invention, sulfonated castor oil and sodium dodecyl sulfate are selected as the compound emulsifier, which can achieve stable emulsification, reduce the dosage of the emulsifier and external components, and reduce the influence on the sizing agent emulsion system.

[0017] 2. The present invention adopts the emulsification stirring method of first low-speed stirring and then high-speed stirring to realize the step-by-step conversion of water and oil components, avoid demulsification, improve the emulsion stability and particle size uniformity, and increase the storage time of the emulsion.

[0018] 3. In the preparation method of the present invention, a neutralizing agent is added before dropping the aqueous solution; or a neutralizing agent is added after the polymerization of modified chlorinated polypropylene, which is beneficial to improving the interlaminar shear strength of the carbon fiber reinforced polypropylene composite material, thereby improving the performance of the composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0020] Figure 1 It is a picture of the sizing agent emulsion prepared in Example 5 of the present invention after being placed for half a year;

[0021] Figure 2 It is a picture of the sizing agent emulsion prepared in Comparative Example 1 of the present invention after being placed for 3 days;

[0022] Figure 3 It is a picture of the solution system formed in Comparative Example 2 of the present invention;

[0023] Figure 4 It is a picture of the product formed in Comparative Example 3 of the present invention;

[0024] Figure 5 It is a bar chart of the interlaminar shear strength of the composite materials prepared with the sizing agents of Examples 1, 5 and Comparative Examples 1, 3 of the present invention;

[0025] Figure 6 It is a bar chart of the interlaminar shear strength of the composite materials prepared with Examples 2-4 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0026] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0027] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should also be understood that when the terms "comprise" and / or "include" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0028] In view of the problems such as poor stability existing in the emulsion made of modified chlorinated polypropylene at present, the present invention proposes a sizing agent based on modified chlorinated polypropylene and its preparation method.

[0029] In a typical embodiment of the present invention, a preparation method of a sizing agent based on modified chlorinated polypropylene is provided, which is obtained by dissolving modified chlorinated polypropylene to obtain an organic solution, dissolving a compound emulsifier in water to obtain an aqueous solution, and dropping the aqueous solution into the organic solution and performing emulsifying stirring.

[0030] The modified chlorinated polypropylene is obtained by a polymerization reaction of chlorinated polypropylene with methyl methacrylate, butyl acrylate, acrylic acid, and isobornyl methacrylate.

[0031] The compound emulsifier is sulfonated castor oil and sodium dodecyl sulfate, and the addition amount of the compound emulsifier is 60-80% of the mass of the modified chlorinated polypropylene.

[0032] The process of the emulsifying stirring is as follows: first, stir at a low speed for 40-70 min, and then stir at a high speed for 20-30 min. The stirring rate of the low-speed stirring is 500-800 rpm, and the stirring rate of the high-speed stirring is 8000-12000 rpm.

[0033] In some embodiments, the mass ratio of sulfonated castor oil to sodium dodecyl sulfate is 1.5-2.5:0.5-1.

[0034] In some embodiments, the organic solvent for dissolving the modified chlorinated polypropylene is toluene or xylene. The ratio of the modified chlorinated polypropylene to the organic solvent is 1:10-20, g:ml.

[0035] In some embodiments, a neutralizing agent is first added to the organic solvent and mixed evenly, then the aqueous solution is dropped in, and then emulsifying stirring is carried out.

[0036] In one or more embodiments, the neutralizing agent is dimethylethanolamine and / or dimethylaminoethanol.

[0037] In one or more embodiments, the neutralizing agent adjusts the pH value of the sizing agent system to 6-8.

[0038] In some embodiments, the solid content of the emulsion formed after emulsification stirring is 1 to 50 wt%.

[0039] In some embodiments, the preparation method of the modified chlorinated polypropylene is as follows: dissolving chlorinated polypropylene to obtain a chlorinated polypropylene solution, dissolving methyl methacrylate, butyl acrylate, acrylic acid, and isobornyl methacrylate to obtain an acrylate monomer solution, adding an initiator to the acrylate monomer solution to dissolve it, heating the chlorinated polypropylene solution under an inert atmosphere condition, and then adding the acrylate monomer solution containing the initiator to carry out a polymerization reaction to obtain the product.

[0040] In one or more embodiments, a neutralizing agent is added after the polymerization reaction to adjust the pH to 7 to 8.

[0041] In one or more embodiments, the mass ratio of chlorinated polypropylene, methyl methacrylate, butyl acrylate, acrylic acid, and isobornyl methacrylate is 5 to 10: 3 to 5: 2 to 4: 1 to 3: 1 to 2.

[0042] Another embodiment of the present invention provides a sizing agent based on modified chlorinated polypropylene, which is obtained by the above preparation method.

[0043] The third embodiment of the present invention provides an application of the sizing agent based on modified chlorinated polypropylene in the preparation of carbon fiber reinforced polypropylene composites.

[0044] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in combination with specific examples and comparative examples.

[0045] Example 1

[0046] A preparation method of a sizing agent based on modified chlorinated polypropylene is as follows:

[0047] (1) Dissolution of chlorinated polypropylene: Weigh 10 g of chlorinated polypropylene (CPP) and dissolve it in 25 ml of butyl acetate, add it to a three-necked flask, and heat and stir at 70 °C for 20 min under a nitrogen atmosphere. Wait until the CPP is completely dissolved and set aside for use.

[0048] (2) Preparation of acrylate modified monomers: Weigh 5 g of methyl methacrylate (MMA), 4 g of butyl acrylate (BA), 3 g of acrylic acid (AA), and 2 g of isobornyl methacrylate (IBOMA).

[0049] (3) Weighing the initiator: Weigh 0.2 g of benzoyl peroxide (BPO) as the initiator, add the BPO to the acrylate monomer mixture, and stir evenly for use.

[0050] (4) Free radical polymerization reaction: Under a nitrogen atmosphere, add the CPP solution in step (1) to a four-necked flask equipped with a condenser, a constant pressure dropping funnel, and a stirring device. After heating to 110 °C, stir evenly. Dropwise add the acrylate-modified monomer in step (2), control the dropping rate so that the monomer is added dropwise within 1.5 h. After the monomer addition is completed, continue to maintain the constant temperature reaction for 2 h. After the reaction is completed, cool naturally.

[0051] (5) Neutralization of the polymerization system: Slowly dropwise add 12 wt% dimethylethanolamine to the system, and control the pH value between 7 and 8.

[0052] (6) Obtaining the precipitate: Add the mixture to methanol to obtain a precipitate. The precipitate is washed twice with acetone solution. Then, it is dried in a vacuum drying oven at 70 °C for 12 h to obtain the modified chlorinated polypropylene resin.

[0053] (7) Dissolution and emulsification of the precipitate: Weigh 1 g of the above-mentioned modified chlorinated polypropylene resin and dissolve it in 15 ml of xylene. Then, dissolve 0.6 g of the compound emulsifier (sulfonated castor oil: sodium dodecyl sulfate = 1.5:1, mass ratio) in 100 ml of deionized water, and slowly add it dropwise to the above system using a constant pressure funnel. First, stir at a speed of 500 rpm for 40 min, and then stir at a speed of 8000 rpm for 20 min to obtain the final aqueous sizing agent emulsion.

[0054] The sizing agent emulsion prepared in this example can still maintain a uniform and stable emulsion state after being placed for half a year.

[0055] Example 2

[0056] A preparation method of a sizing agent based on modified chlorinated polypropylene is as follows:

[0057] (1) Dissolution of chlorinated polypropylene: Weigh 8 g of chlorinated polypropylene (CPP) and dissolve it in 20 ml of butyl acetate. Add it to a three-necked flask and heat and stir at 70 °C for 20 min under a nitrogen environment. After the CPP is completely dissolved, set it aside for use.

[0058] (2) Preparation of acrylate-modified monomer: Weigh 3.5 g of methyl methacrylate (MMA), 3 g of butyl acrylate (BA), 2 g of acrylic acid (AA), and 2 g of isobornyl methacrylate (IBOMA).

[0059] (3) Weighing the initiator: Weigh 0.2 g of benzoyl peroxide (BPO) as the initiator, add BPO to the acrylic monomer mixture, and stir evenly for use.

[0060] (4) Free radical polymerization reaction: Under a nitrogen atmosphere, add the CPP solution in step (1) to a four-necked flask equipped with a condenser, a constant pressure dropping funnel, and a stirring device. After heating to 110 °C, stir evenly. Dropwise add the acrylate modified monomer in step (2), and control the dropping rate so that the monomer is added dropwise within 2 h. After the monomer addition is completed, continue to maintain the constant temperature reaction for 2.5 h. After the reaction is completed, cool naturally.

[0061] (5) Neutralization of the polymerization system: Slowly dropwise add 12 wt% dimethylethanolamine to the system, and control the pH value between 7 and 8.

[0062] (6) Obtaining the precipitate: Add the mixture to methanol to obtain a precipitate. The precipitate is washed twice with acetone solution. Then, it is dried in a vacuum drying oven at 75 °C for 12 h to obtain the modified chlorinated polypropylene resin.

[0063] (7) Dissolution and emulsification of the precipitate: Weigh 1 g of the above-mentioned modified chlorinated polypropylene resin and dissolve it in 20 ml of toluene. Then, dissolve 0.7 g of the compound emulsifier (sulfonated castor oil: sodium dodecyl sulfate = 2:1, mass ratio) in 100 ml of deionized water, and slowly add it dropwise to the above system using a constant pressure funnel. First, stir at a speed of 600 rpm for 50 min, and then stir at a speed of 9000 rpm for 25 min to obtain the final aqueous sizing agent emulsion.

[0064] The sizing agent emulsion prepared in this example can still maintain a uniform and stable emulsion state after being placed for half a year.

[0065] Example 3

[0066] A preparation method of a sizing agent based on modified chlorinated polypropylene is as follows:

[0067] (1) Dissolution of chlorinated polypropylene: Weigh 8 g of chlorinated polypropylene (CPP) and dissolve it in 15 ml of butyl acetate. Add it to a three-necked flask and heat and stir at 70 °C for 20 min under a nitrogen environment. After the CPP is completely dissolved, set it aside for use.

[0068] (2) Preparation of acrylate modified monomer: Weigh 3 g of methyl methacrylate (MMA), 2 g of butyl acrylate (BA), 2 g of acrylic acid (AA), and 1.5 g of isobornyl methacrylate (IBOMA).

[0069] (3) Weighing the initiator: Weigh 0.3 g of benzoyl peroxide (BPO) as the initiator, add BPO to the acrylic monomer mixture, and stir evenly for use.

[0070] (4) Free radical polymerization reaction: Under a nitrogen atmosphere, add the CPP solution in step (1) to a four-necked flask equipped with a condenser, a constant pressure dropping funnel, and a stirring device. After heating to 110 °C, stir evenly. Dropwise add the acrylate-modified monomer in step (2), and control the dropping rate so that the monomer is added dropwise within 1.5 h. After the monomer addition is completed, continue to maintain the constant temperature reaction for 3 h. After the reaction is completed, cool naturally.

[0071] (5) Neutralization of the polymerization system: Slowly dropwise add 12 wt% dimethylaminoethanol to the system, and control the pH value between 7 and 8.

[0072] (6) Obtaining the precipitate: Add the mixture to methanol to obtain a precipitate. The precipitate is washed twice with acetone solution. Then, it is dried in a vacuum drying oven at 80 °C for 12 h to obtain the modified chlorinated polypropylene resin.

[0073] (7) Dissolution and emulsification of the precipitate: Weigh 1 g of the above-mentioned modified chlorinated polypropylene resin and dissolve it in 15 ml of toluene. Then, dissolve 0.8 g of the compound emulsifier (sulfonated castor oil: sodium dodecyl sulfate = 2.5:1.5, mass ratio) in 100 ml of deionized water, and slowly add it dropwise to the above system using a constant pressure funnel. First, stir at a speed of 700 rpm for 60 min, and then stir at a speed of 10,000 rpm for 30 min to obtain the final aqueous sizing agent emulsion.

[0074] The sizing agent emulsion prepared in this example can still maintain a uniform and stable emulsion state after being placed for half a year.

[0075] Example 4

[0076] A preparation method of a sizing agent based on modified chlorinated polypropylene is as follows:

[0077] (1) Dissolution of chlorinated polypropylene: Weigh 6 g of chlorinated polypropylene (CPP) and dissolve it in 15 ml of butyl acetate. Add it to a three-necked flask and heat and stir at 70 °C for 20 min under a nitrogen environment. Wait until the CPP is completely dissolved and set aside.

[0078] (2) Preparation of acrylate-modified monomer: Weigh 3 g of methyl methacrylate (MMA), 2 g of butyl acrylate (BA), 1.5 g of acrylic acid (AA), and 1 g of isobornyl methacrylate (IBOMA).

[0079] (3) Weigh the initiator: Weigh 0.2 g of benzoyl peroxide (BPO) as the initiator, add BPO to the acrylic monomer mixture, and stir evenly for use.

[0080] (4) Free radical polymerization reaction: Under a nitrogen atmosphere, add the CPP solution in step (1) into a four-necked flask equipped with a condenser, a constant pressure dropping funnel, and a stirring device. After heating to 110 °C, stir evenly. Dropwise add the acrylate modified monomer in step (2), and control the dropping rate so that the monomer is added dropwise within 2 h. After the monomer addition is completed, continue to maintain the constant temperature reaction for 2 h. After the reaction is completed, cool naturally.

[0081] (5) Neutralization of the polymerization system: Slowly dropwise add 12 wt% dimethylethanolamine to the system, and control the pH value between 7 and 8.

[0082] (6) Obtaining the precipitate: Add the mixture to methanol to obtain a precipitate. The precipitate is washed twice with acetone solution. Then, it is dried in a vacuum drying oven at 75 °C for 12 h to obtain the modified chlorinated polypropylene resin.

[0083] (7) Dissolution and emulsification of the precipitate: Weigh 1 g of the above-mentioned modified chlorinated polypropylene resin and dissolve it in 10 ml of toluene. Then, dissolve 0.75 g of the compound emulsifier (sulfonated castor oil: sodium dodecyl sulfate = 2.5:1, mass ratio) in 100 ml of deionized water, and slowly add it dropwise to the above system using a constant pressure funnel. First, stir at a speed of 800 rpm for 70 min, then stir at a speed of 11000 rpm for 30 min, and after ultrasonic treatment for 20 min, the final aqueous sizing agent emulsion is obtained.

[0084] The sizing agent emulsion prepared in this example can still maintain a uniform and stable emulsion state after being placed for half a year.

[0085] Example 5

[0086] A preparation method of a sizing agent based on modified chlorinated polypropylene is as follows:

[0087] (1) Dissolution of chlorinated polypropylene: Weigh 10 g of chlorinated polypropylene (CPP) and dissolve it in 25 ml of butyl acetate. Add it to a three-necked flask and heat and stir at 70 °C for 20 min under a nitrogen environment. Wait until the CPP is completely dissolved and set aside.

[0088] (2) Preparation of acrylate modified monomer: Weigh 5 g of methyl methacrylate (MMA), 4 g of butyl acrylate (BA), 3 g of acrylic acid (AA), and 2 g of isobornyl methacrylate (IBOMA).

[0089] (3) Weigh the initiator: Weigh 0.2 g of benzoyl peroxide (BPO) as the initiator, add BPO to the acrylic monomer mixture, and stir evenly for use.

[0090] (4) Free radical polymerization reaction: Under a nitrogen atmosphere, add the CPP solution in step (1) to a four-necked flask equipped with a condenser, a constant pressure dropping funnel, and a stirring device. After heating to 110 °C, stir evenly. Dropwise add the acrylate modified monomer in step (2), control the dropping rate, and complete the dropping of the monomer within 1.5 h. After the monomer dropping is completed, continue to maintain the constant temperature reaction for 2 h. After the reaction is completed, cool naturally.

[0091] (5) Obtain the precipitate: Add the mixture to methanol to obtain the precipitate. Wash the precipitate twice with acetone solution. Then, dry it in a vacuum drying oven at 70 °C for 12 h to obtain the modified chlorinated polypropylene resin.

[0092] (6) Dissolution and emulsification of the precipitate: Weigh 1 g of the above-mentioned modified chlorinated polypropylene resin and dissolve it in 15 ml of xylene. Then, dissolve 0.8 g of the compound emulsifier (sulfonated castor oil: sodium dodecyl sulfate = 2:1, mass ratio) in 100 ml of deionized water, and slowly add it dropwise to the above system using a constant pressure funnel. First, stir at a speed of 600 rpm for 50 min, and then stir at a speed of 9000 rpm for 30 min to obtain the final aqueous sizing agent emulsion.

[0093] After the sizing agent emulsion prepared in this example was placed for half a year, it could still maintain a uniform and stable emulsion state, as Figure 1 shown.

[0094] Comparative Example 1

[0095] This comparative example is the same as Example 5, except that:

[0096] In step (7), sodium dodecyl sulfate: fatty acid polyethylene 10 ester (SE10) = 2:1 (mass ratio) is used as the compound emulsifier, and the addition amount of the compound emulsifier is 1 g.

[0097] After the sizing agent emulsion prepared in this comparative example was placed for 3 days, the emulsion was stratified, as Figure 2 shown.

[0098] Comparative Example 2

[0099] This comparative example is the same as Example 5, except that:

[0100] In step (7), directly stir at a speed of 9000 rpm (high speed) for 45 min.

[0101] This comparative example could not prepare a uniform and stable emulsion, and there were flocs in the stirred system, as Figure 3 shown.

[0102] Comparative Example 3

[0103] This comparative example is the same as Example 1, except that: step (7) is the same as Comparative Example 1.

[0104] A uniform and stable emulsion could not be prepared in this comparative example. After stirring, the system was in a gel state, as Figure 4 shown.

[0105] Experimental process for testing the interlaminar shear strength of the composite material:

[0106] The sizing agent on the surface of commercial carbon fiber was removed by heat treatment in a muffle furnace. The concentration of the prepared sizing agent was adjusted to 1.5%. After sizing the carbon fiber, it was dried at 105 °C for 20 min to obtain sized carbon fiber. According to the JC / T 773-2010 standard, interlaminar shear test samples were prepared, and a universal tensile tester was used to measure the interlaminar shear strength of the sized carbon fiber / polypropylene resin composite material. The size of the composite material sample was 20×10×2 mm. The ILSS was calculated according to the following formula:

[0107]

[0108] In the formula, P max —the maximum load (N) at the shear fracture of the specimen; b—the width (m) of the sample; h—the thickness (m) of the sample. Each group of samples was tested 10 times, and the average value was taken.

[0109] The interlaminar shear strengths of the composite materials prepared with the sizing agents of Example 1, 5 and Comparative Examples 1, 3 are as Figure 5 shown. The interlaminar shear strength of the carbon fiber / polypropylene resin composite material prepared with the emulsifier prepared by compounding non-sulfonated castor oil and sodium dodecyl sulfate was relatively low. Using the emulsifier prepared by compounding non-sulfonated castor oil and sodium dodecyl sulfate could significantly improve the interlaminar shear strength of the composite material. By comparing Example 1 and Example 5, it can be seen that adding a neutralizing agent could further increase the interlaminar shear strength of the composite material.

[0110] The interlaminar shear strengths of the composite materials prepared with Examples 2-4 are as Figure 6 shown, indicating that the interlaminar shear strength of the formed carbon fiber / polypropylene resin composite material is higher.

[0111] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a sizing agent based on modified chlorinated polypropylene, characterized in that, dissolve the modified chlorinated polypropylene to obtain an organic solution, dissolve the compound emulsifier in water to obtain an aqueous solution, drop the aqueous solution into the organic solution, and carry out emulsifying stirring to obtain it; the modified chlorinated polypropylene is obtained by a polymerization reaction of chlorinated polypropylene with methyl methacrylate, butyl acrylate, acrylic acid, and isobornyl methacrylate; the compound emulsifier is sulfonated castor oil and sodium dodecyl sulfate, and the addition amount of the compound emulsifier is 60-80% of the mass of the modified chlorinated polypropylene; the process of the emulsifying stirring is: first stir at a low speed for 40-70 min, and then stir at a high speed for 20-30 min. The stirring rate of the low-speed stirring is 500-800 rpm, and the stirring rate of the high-speed stirring is 8000-12000 rpm.

2. The preparation method of the sizing agent based on modified chlorinated polypropylene according to claim 1, characterized in that, the mass ratio of sulfonated castor oil to sodium dodecyl sulfate is 1.5-2.5:0.5-1.

3. The preparation method of the sizing agent based on modified chlorinated polypropylene according to claim 1, characterized in that, the organic solution for dissolving the modified chlorinated polypropylene is toluene or xylene, and the ratio of the modified chlorinated polypropylene to the organic solution is 1:10-20, g:mL.

4. The preparation method of the sizing agent based on modified chlorinated polypropylene according to claim 1, characterized in that, first add a neutralizing agent to the organic solution and mix evenly, then drop the aqueous solution, and then carry out emulsifying stirring.

5. The preparation method of the sizing agent based on modified chlorinated polypropylene according to claim 4, characterized in that, the neutralizing agent is dimethylethanolamine and / or dimethylaminoethanol; or, the neutralizing agent adjusts the pH value of the sizing agent system to 6-8.

6. The preparation method of the sizing agent based on modified chlorinated polypropylene according to claim 1, characterized in that, the solid content of the emulsion formed after emulsifying stirring is 1-50 wt%.

7. The preparation method of the sizing agent based on modified chlorinated polypropylene according to claim 1, characterized in that, the preparation method of the modified chlorinated polypropylene is: dissolve the chlorinated polypropylene to obtain a chlorinated polypropylene solution, dissolve methyl methacrylate, butyl acrylate, acrylic acid, and isobornyl methacrylate to obtain an acrylate monomer solution, add an initiator to the acrylate monomer solution and dissolve it, under an inert atmosphere condition, heat the chlorinated polypropylene solution, and then add the acrylate monomer solution containing the initiator, and carry out a polymerization reaction to obtain it.

8. The preparation method of the sizing agent based on modified chlorinated polypropylene according to claim 7, characterized in that, add a neutralizing agent after the polymerization reaction to adjust the pH to 7-8; or, the mass ratio of chlorinated polypropylene, methyl methacrylate, butyl acrylate, acrylic acid, and isobornyl methacrylate is 5-10:3-5:2-4:1-3:1-2.

9. A sizing agent based on modified chlorinated polypropylene, characterized in that, obtained by the preparation method according to any one of claims 1-8.

10. Use of the sizing agent based on modified chlorinated polypropylene according to claim 9 in the preparation of carbon fiber reinforced polypropylene composites.

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