CN105176008A - Formula and preparing method of carbon fiber sizing agent for reinforcing polypropylene - Google Patents

Abstract

The invention discloses a formula and preparing method of a carbon fiber sizing agent for reinforcing polypropylene. Compared with traditional solvent type sizing agents, the prepared sizing agent has the advantages of being low in toxicity, low in cost, low in pollution and the like with water serving as the continuous phase. Besides, the sizing agent is suitable for a polypropylene resin matrix and solves the problem of poor cohesiveness between carbon fiber and polypropylene resin. When the sizing agent is used for sizing, the post processing capacity of carbon fiber is improved remarkably, the cohesiveness of the interface between carbon fiber and polypropylene matrix resin is high, and the macroscopical mechanical strength of a carbon fiber/polypropylene composite material is improved to a large extent.

Description

A kind of formula and preparation method of carbon fiber sizing agent for reinforced polypropylene

technical field

The invention relates to a formulation of an emulsion carbon fiber sizing agent and a preparation method thereof, in particular to a formulation of a graphene oxide modified emulsion carbon fiber sizing agent and a preparation method thereof.

Background technique

Carbon fiber has excellent properties such as high specific strength, high specific modulus, high temperature resistance, and corrosion resistance. It is used as a reinforcement of composite materials and is widely used in various fields. At present, the commonly used carbon fiber resin-based composite materials are mainly thermosetting resins. In the past two decades, with the rapid development of industry, composite materials have been widely used in various industries. The problem of volatilization of harmful gases and waste recycling of thermosetting resin-based composites is particularly difficult. Thermoplastic resin-based composites are attracting more and more attention in industrial production because of their recyclability, shorter product molding processing time and better toughness.

Polypropylene resin has excellent comprehensive performance and low price, which are the prerequisites for its wide application. However, its creep resistance and dimensional stability are poor, and its tensile, bending and impact properties cannot meet the requirements of actual production and application. Therefore, polypropylene mostly adopts the method of adding reinforcements to improve the above deficiencies. Carbon fiber is a kind of reinforced material with excellent performance, which is widely used in many fields such as aerospace, medical equipment and sports equipment. It is widely used as a reinforcement for polypropylene. However, carbon fibers exhibit surface chemical inertness, low surface energy, and few chemically active groups. In addition, polypropylene is a non-polar polymer, which makes it difficult for polypropylene to fully wet carbon fibers and form chemical bonds between the two when preparing carbon fiber/polypropylene composites. The interface bonding strength is poor, which seriously hinders It prevents the transmission of external stress from the matrix polypropylene to the reinforcing fiber, which seriously affects the reinforcing effect of carbon fiber.

In order to improve the interfacial bonding strength of carbon fiber and polypropylene, modification of the carbon fiber surface and polypropylene matrix is required. Maleic anhydride grafted polypropylene is usually used as a compatibilizer for polypropylene to improve the activity of polypropylene. The surface modification methods of carbon fibers usually include oxidation treatment, high-energy radiation, laser, plasma and other methods. They can effectively increase the active functional groups on the surface of carbon fibers, thereby increasing the interfacial bonding strength between them and the matrix resin. However, these fiber surface treatment methods consume too much energy, and have certain damage to the carbon fiber itself, which affects the strength of the carbon fiber.

Therefore, an economical method without compromising the strength of carbon fibers needs to be developed urgently.

Contents of the invention

In order to overcome the above disadvantages, the present invention provides a formula and preparation method of a carbon fiber epoxy resin sizing agent modified by graphene oxide. The sizing agent has the advantages of easy preparation, low environmental pollution, easy implementation and high stability.

Another object of the present invention is to provide a formula and a preparation method of a graphene oxide modified emulsion carbon fiber epoxy resin sizing agent. The formulation is simple to implement, and the problem of poor interfacial bonding between carbon fiber and polypropylene can be significantly improved due to the addition of graphene oxide.

The emulsion type carbon fiber epoxy resin sizing agent modified by graphene oxide of the present invention is made from the following raw materials in parts by weight:

Epoxy resin: 100 parts;

Diluent: 5~55.0 parts

Emulsifier: 5~15.0 parts;

Penetrant: 1~5.0 parts;

Graphene oxide: 0~15.0 parts;

Deionized water: 150 parts.

The main slurry selected by the sizing agent of the present invention is glycidyl ether type epoxy resin E-44, E-51 or E-55.

The diluent used in the present invention is acetone, methyl ethyl ketone or n-butanol.

The emulsifier selected in the present invention is octylphenol polyoxyethylene ether (OP-10), polyoxyethylene sorbitan monooleate (Tween-80), agricultural milk 1601 or castor oil polyoxyethylene ether (EL-40 ).

The penetrant of the present invention is secondary octanol polyoxyethylene ether (JFC-2).

The graphene oxide used in the present invention can be made from flake graphite by the improved Hummers method, or can be purchased directly from commercially available products. The performance parameters and characteristics of graphene oxide are: thickness 0.9~1.5nm, sheet diameter 2~5μm.

The water used in the present invention is deionized water. The water content of the sizing agent is controlled according to the required concentration of the sizing agent. Generally, in order to reduce the cost of the sizing agent during transportation, it is preferable to use less water when preparing the sizing agent, and then add additional water to dilute to the required concentration when sizing the fibers. In a preferred embodiment of the present invention, the mass ratio of water to main slurry is 1.5:1.

In a preferred embodiment, the graphene oxide modified emulsion type carbon fiber epoxy resin sizing agent is made of the following raw materials in parts by weight:

Epoxy resin: 100 parts;

Diluent: 10~50.0 parts

Emulsifier: 6.5~13.5 parts;

Penetrant: 1.5~4.5 parts;

Graphene oxide: 3~10.0 parts;

Deionized water: 150 parts.

The preparation method of described graphene oxide modified emulsion type carbon fiber epoxy resin sizing agent comprises as follows:

The preparation method of the sizing agent emulsion of the present invention is realized by a phase inversion emulsification method. Place the above-mentioned main slurry epoxy resin, emulsifier, diluent and penetrant in a beaker at 50°C, heat in a water bath, and stir to mix evenly. Use a high-shear dispersing emulsifier to disperse the above mixture at a constant rate of 6000~9000rpm at room temperature and normal pressure at a high speed, and at the same time add water dropwise to the above mixture at a rate of 2 parts/min. After 80 minutes, the sizing agent emulsion was obtained. Finally, the graphene oxide is poured into the above-mentioned emulsion in the form of an aqueous solution to obtain a graphene oxide-modified carbon fiber emulsion-type sizing agent.

The carbon fiber used in the present invention is the carbon fiber of model T700SC (12k) produced by Japan Toray Co., Ltd., and is subjected to desizing treatment before sizing. Soxhlet extraction method is used for desizing: on a stainless steel rectangular frame, carbon fiber bundles of appropriate length are evenly wound in it and placed in a Soxhlet extractor. Assemble the Soxhlet extraction device, add an appropriate volume of acetone-ethanol mixture, and adjust the siphon of the Soxhlet extractor 4 times per hour by controlling the voltage of the electric heating mantle. After 36 hours, the carbon fibers were rinsed with deionized water several times, then dried in a constant temperature drying oven at 100°C for 4 hours, cut into chopped fibers with an average length of 3 mm by machine, cooled and placed in a desiccator for later use.

The method for sizing carbon fiber by the carbon fiber sizing agent of the present invention is: adding water to dilute the above-mentioned carbon fiber sizing agent to a solid content of 0.5 to 3.0 wt%, and then adopting the dipping method to sizing the diluted graphene oxide modified emulsion carbon fiber epoxy resin coating on carbon fibers. The method is simple to operate and easy to implement.

In the above method for sizing carbon fibers, the immersion time of carbon fibers in the modified water-soluble carbon fiber sizing agent is 30s, and the carbon fibers are dried at 100° C. for 10 minutes after immersion.

The matrix polypropylene used in the present invention is provided by Dongguan Changping Yingke Plastic Raw Materials Management Department, and the polypropylene is graft-modified polypropylene containing 5.0-10.0 parts of maleic anhydride.

The carbon fiber reinforced polypropylene composite material in the present invention is prepared by extrusion-injection molding process. Wherein, the consumption of chopped carbon fiber is 10wt%.

The present invention has the following advantages:

1. The sizing agent is an emulsion type sizing agent, which uses water as the medium, does not pollute the environment, has low cost and good stability.

2. The soft lamellar structure of graphene oxide is conducive to the formation of a carbon fiber/polypropylene interface layer with better toughness.

3. After using the sizing agent for sizing, the wear resistance of carbon fiber is improved, the amount of fuzz is reduced, and the post-processing performance of carbon fiber is improved.

4. Both graphene oxide and the epoxy resin of the main slurry contain a large number of oxygen-containing functional groups, which can form chemical bonds with the anhydride groups of the matrix maleic anhydride-grafted polypropylene, thereby improving the interface of carbon fiber/polypropylene composites. Bond strength and significantly improve the mechanical strength of composite materials.

5. The preparation method of the sizing agent is simple and easy to implement.

Detailed ways

The present invention will be described in detail below in conjunction with specific preferred embodiments. Unless otherwise specified, the contents of each component of the sizing agent in the following embodiments are by weight.

Example 1

Take each raw material by the following parts by weight:

Epoxy resin E-44: 100 parts;

Acetone: 10.0 parts;

EL-40: 6.5 parts;

JFC-2: 1.5 copies;

Graphene oxide: 3.0 parts;

Deionized water: 150 parts.

Prepare graphene oxide modified emulsion type carbon fiber epoxy resin sizing agent as follows:

Place the above-mentioned main slurry epoxy resin, emulsifier, diluent and penetrant in a beaker at 50°C, heat in a water bath, and stir to mix evenly. A high-shear dispersing emulsifier was used to disperse the above mixture at a constant rate of 6000 rpm at room temperature and normal pressure at a high speed, and at the same time, water was added dropwise to the above mixture at a rate of 2 parts/min. After 80 minutes, the sizing agent emulsion was obtained. Finally, the graphene oxide is poured into the above-mentioned emulsion in the form of an aqueous solution to obtain a graphene oxide-modified carbon fiber emulsion-type sizing agent.

Example 2

Take each raw material by the following parts by weight:

Epoxy resin E-51: 100 parts;

Acetone: 50.0 parts;

Tween-80: 13.5 parts;

JFC-2: 4.5 copies;

Graphene oxide: 10 parts;

Deionized water: 150 parts.

Prepare graphene oxide modified emulsion type carbon fiber epoxy resin sizing agent as follows:

Place the above-mentioned main slurry epoxy resin, emulsifier, diluent and penetrant in a beaker at 50°C, heat in a water bath, and stir to mix evenly. A high-shear dispersing emulsifier was used to disperse the above mixture at a constant rate of 9000 rpm at room temperature and normal pressure at a high speed, and at the same time, water was added dropwise to the above mixture at a rate of 2 parts/min. After 80 minutes, the sizing agent emulsion was obtained. Finally, the graphene oxide is poured into the above-mentioned emulsion in the form of an aqueous solution to obtain a graphene oxide-modified carbon fiber emulsion-type sizing agent.

Example 3

Take each raw material by the following parts by weight:

Epoxy resin E-55: 100 parts;

Methyl ethyl ketone: 20 parts;

Agricultural Milk 1601: 10 servings;

JFC-2: 2.5 copies;

Graphene oxide: 5 parts;

Deionized water: 150 parts.

Prepare graphene oxide modified emulsion type carbon fiber epoxy resin sizing agent as follows:

Place the above-mentioned main slurry epoxy resin, emulsifier, diluent and penetrant in a beaker at 50°C, heat in a water bath, and stir to mix evenly. A high-shear dispersing emulsifier was used to disperse the above mixture at a constant rate of 7000 rpm at room temperature and normal pressure at a high speed, and at the same time, water was added dropwise to the above mixture at a rate of 2 parts/min. After 80 minutes, the sizing agent emulsion was obtained. Finally, the graphene oxide is poured into the above-mentioned emulsion in the form of an aqueous solution to obtain a graphene oxide-modified carbon fiber emulsion-type sizing agent.

Example 4

Take each raw material by the following parts by weight:

Epoxy resin E-51: 100 parts;

Butanol: 30 parts;

OP-10: 8 parts;

JFC-2: 3.5 copies;

Graphene oxide: 7 parts;

Deionized water: 150 parts.

Prepare graphene oxide modified emulsion type carbon fiber epoxy resin sizing agent as follows:

Place the above-mentioned main slurry epoxy resin, emulsifier, diluent and penetrant in a beaker at 50°C, heat in a water bath, and stir to mix evenly. A high-shear dispersing emulsifier was used to disperse the above mixture at a constant rate of 7000 rpm at room temperature and normal pressure at a high speed, and at the same time, water was added dropwise to the above mixture at a rate of 2 parts/min. After 80 minutes, the sizing agent emulsion was obtained. Finally, the graphene oxide is poured into the above-mentioned emulsion in the form of an aqueous solution to obtain a graphene oxide-modified carbon fiber emulsion-type sizing agent.

The sizing method of each sizing agent is as follows: dilute the sizing agent in the above-mentioned examples to a solid content of 1.5wt%, and attach the sizing agent to the carbon fiber by dipping. The dipping time is 30s. Dry for 10min. Finally, chopped carbon fibers with an average of 3 mm are cut for future use.

The standing stability of the sizing agent emulsion, the stiffness of the carbon fiber, the amount of wool, the number of abrasions and the impact strength, flexural strength and tensile strength of the carbon fiber reinforced polypropylene composite material were measured at room temperature and normal pressure. The results are listed in Table 1 .

The evaluation method is as follows:

1. The standing stability of sizing agent

Measure 30mL of sizing agent and place it in a plastic bottle with a stopper, and place it at room temperature for a certain period of time to observe whether there is delamination. Stability ratings are as follows:

Level Ⅰ: 20-day stratification;

Level Ⅱ: no layer for 30 days;

2. The amount of wool

The carbon fiber bundle is clamped by two polyurethane sponges with dimensions of 40mm (length) x 10mm (width) x 5mm (thickness), and the entire polyurethane sponge has a load of 200g. The carbon fiber bundle passes through the short side at a speed of 1m/min, and the weight of the wool attached to the sponge after 10 minutes is measured, which is the amount of friction hair of the carbon fiber bundle.

3. Stiffness

The performance of carbon fiber when it is subjected to bending force is very important, because carbon fiber will be subjected to repeated bending stress during the weaving process, especially when weaving multi-dimensional fabrics, the bending angle of carbon fiber on the loom is very large, and the bending effect is very large. Bending deformation will occur, so carbon fiber is required to have moderate flexibility. The stiffness of carbon fiber before and after sizing can reflect the flexibility of carbon fiber to a certain extent, the greater the stiffness, the lower the flexibility.

The determination of stiffness adopts the principle that a fixed-length fiber is suspended at its midpoint and will hang at a certain angle. The carbon fiber must first be unwound. Pass the carbon fiber through the yarn guide hook of the unwinding device, and wind it around three stainless steel wheels, and wind it on the winding drum with a speed of about 10mm/s, and start the motor for winding.

The fibers after unwinding were tested for stiffness. A stainless steel hook with a radius of 10mm is used as the suspension point, and there is a sliding ruler 60mm below the suspension point. Measure 500mm of unwound carbon fiber and hang it on the hook, so that the length of the sample protruding from both sides is equal, and after standing for 30s Measure the distance between the ends.

4. Wear resistance

The wear resistance test of carbon fiber was carried out on the LFY-109B wear tester. The diameter of the godet roller is 10mm, the diameter of the stainless steel roller with sandpaper is 15mm, and the included angle between the two godet rollers and the stainless steel roller is 120°. The load G is 200g, the carbon fiber bundle reciprocates at a constant speed of 120 times per minute, and rubs repeatedly with the sandpaper on the stainless steel roller, and records the number of times when the fiber is broken.

5. The impact strength, flexural strength and tensile strength of chopped carbon fiber/polypropylene composites are measured according to GB/T1043-93, GB/T1447-2005 and GB/T1449-2005 respectively.

Table 1

sample Stability series Amount of carbon fiber wool (mg) Carbon fiber stiffness (mm) Carbon fiber wear resistance (times) Composite material impact strength (KJ/m ² ) Composite bending strength (MPa) Composite tensile strength (MPa) Example 1 I 4.9 70 1624 8.6 83.84 63.19 Example 2 II 3.9 65 1765 9.1 95.26 69.79 Example 3 II 4.4 69 1671 8.8 86.59 66.29 Example 4 II 4.1 67 1697 8.9 89.29 67.28

Claims (8)

1. a prescription and preparation method thereof of the carbon fiber sizing agent of reinforced polypropylene, it is characterized in that, described graphene oxide modified emulsion type carbon fiber epoxy resin sizing agent adopts the raw material of following parts by weight to make: Epoxy resin: 100 parts; Diluent: 5~55.0 parts Emulsifier: 5~15.0 parts; Penetrant: 1~5.0 parts; Graphene oxide: 0~15.0 parts; Deionized water: 150 parts. 2. graphene oxide modified emulsion type carbon fiber epoxy resin sizing agent as claimed in claim 1, is characterized in that, described graphene oxide modified emulsion type carbon fiber epoxy resin sizing agent is to adopt the raw material of following parts by weight production: Epoxy resin: 100 parts; Diluent: 10~50.0 parts Emulsifier: 6.5~13.5 parts; Penetrant: 1.5~4.5 parts; Graphene oxide: 3~10.0 parts; Deionized water: 150 parts. 3. The graphene oxide modified emulsion type carbon fiber epoxy resin sizing agent according to claim 1 or 2, characterized in that: the thickness of graphene oxide is 0.9~1.5nm, and the sheet diameter is 2~5μm. 4. root on the graphene oxide modified emulsion type carbon fiber epoxy resin as described in any one of claim 1-3 The slurry is characterized in that the mass ratio of deionized water to the main slurry is 1.5:1. 5. The emulsion type carbon fiber epoxy resin sizing agent modified by graphene oxide as claimed in any one of claims 1-4, characterized in that: the epoxy resin comprises E-44, E-51 or E-55 The diluent is acetone, methyl ethyl ketone or n-butanol; the emulsifier is octylphenol polyoxyethylene ether (OP-10), polyoxyethylene sorbitan monooleate (Tween-80), agricultural milk 1601 or castor oil ethoxylate (EL-40); the penetrant 2-octyl alcohol ethoxylate (JFC-2). 6. the preparation method of the carbon fiber epoxy resin sizing agent of graphene oxide modification as described in any one of claim 1-5 comprises the steps: Put a certain amount of main slurry epoxy resin, emulsifier, diluent and penetrant in a beaker at 50°C and heat it in a water bath, and stir and mix evenly. Disperse the above mixture at high speed under normal pressure, and at the same time add water dropwise to the above mixture at a rate of 2 parts/min. After 80 minutes, a sizing agent emulsion is obtained. Finally, graphene oxide is poured into the above emulsion in the form of an aqueous solution to obtain the oxidized Graphene modified carbon fiber emulsion type sizing agent. 7. The emulsion type carbon fiber epoxy resin sizing agent modified by graphene oxide as claimed in any one of claims 1-6 is diluted with water to 0.5 ~ 3.0wt%, and then the diluted sizing agent is attached to the carbon fiber by dipping method surface, and to test the post-processing properties of sized carbon fibers. 8. According to the formula, preparation and sizing method of the graphene oxide modified emulsion type carbon fiber epoxy resin sizing agent according to any one of claims 1-7, prepare carbon fiber reinforced polypropylene thermoplastic resin composite material, and test mechanical properties , wherein the polypropylene resin is a polypropylene resin containing 5.0 to 10.0 parts of maleic anhydride graft-modified.