CN1775513A - Preparation Method of Microwave In-Situ Polymerization of Long Glass Fiber Reinforced ABS Composites - Google Patents

Abstract

The present invention provides a preparation method of microwave in-situ polymerized long glass fibre reinforced ABS composite material. It is mainly characterized by that after the glass fibre cloth is impregnated with polymer monomer with low viscousity and oligopolymer, said glass fibre cloth is laid in a glass fibre reinforced plastic mould, then it utilizes microwave to make in-situ polymerization reaction so as to obtain the invented composite material plate.

Description

Preparation Method of Microwave In-Situ Polymerization of Long Glass Fiber Reinforced ABS Composites

technical field

The invention relates to a preparation method for preparing long glass fiber-reinforced ABS composite materials by microwave in-situ polymerization, which can be used for preparing high-performance glass fiber-reinforced thermoplastic composite materials and belongs to the field of polymer-based composite materials.

Background technique

ABS is a thermoplastic engineering plastic with excellent performance and relatively low price. As people have higher and higher requirements on the performance and environmental protection of engineering plastics, the research and development of glass fiber reinforced ABS thermoplastic composite materials with good cost performance is constantly being paid attention to by people, and the application prospects are broad.

One of the key technologies for preparing fiber-reinforced thermoplastic composites is the impregnation process of fibers and thermoplastic resins. The impregnation methods currently used in industry include melt impregnation method, melt impregnation method, suspension impregnation method, and hybrid fiber method. The process of melt impregnation is simple, and it is a composite method commonly used in industry at present. However, due to the high melt viscosity of thermoplastic resin, it is difficult for the resin to impregnate the surface of a single fiber in the fiber bundle, and the mixing of fibers and molten resin is generally done in It is carried out in an injection molding machine or a twin-screw, so the melt impregnation method is generally used in the preparation of short glass fiber reinforced thermoplastic composites in the industry; although the melt impregnation method and suspension impregnation method can make the polymer solution or polymer particles easier to soak Fiber bundles, but the solution diffuses along the polymer interface during the process of removing the solution will cause interface defects; the hybrid fiber method needs to solve the problem of uniform coating of reinforcing fibers during the melting process of thermoplastic fibers, and the production process is relatively complicated. This patent uses an in-situ polymerization method to well solve the problem of thermoplastic resin impregnating reinforcing fibers.

The application of microwave technology in polymer-based composite materials is a new technology developed in the past ten years, and most of them are used in the repair, connection and separation of composite materials. In the preparation of polymer-based composite materials, there are many researches on microwave vulcanization and resin curing. Lee et al. first applied microwave radiation to the curing of composite materials. The application of microwave radiation to resin polymerization was studied late. In 1994, Murray et al. applied microwave to emulsion polymerization for the first time. The innovation of this patent lies in the first use of microwave technology for in-situ polymerization to prepare thermoplastic composite materials.

In-situ polymerization is to impregnate thermoplastic polymer monomers with reinforcing fibers, and then simultaneously complete the two processes of monomer polymerization and fiber compounding during the heating process. The polymerization of this patent uses microwave radiation heating, which is different from the heat transfer from outside to inside of thermal polymerization, but heats inside and outside at the same time, with fast heating speed and high efficiency. At the same time, due to the heat transfer direction and thermal gradient direction of microwave heating Different heating can improve the bonding performance of the composite interface.

Therefore, the method for preparing composite materials by microwave in-situ polymerization proposed and used in the present invention has solved the problem of impregnating reinforcing fibers with thermoplastic resins, with fewer procedures and low cost. Compared with thermal polymerization using a flat vulcanizer, microwave technology , the heating speed is fast, the efficiency is high, the rubber phase distribution in the resin matrix is uniform and fine, and the prepared composite material has good mechanical properties.

Contents of the invention

The purpose of the present invention is to provide a method for preparing a long glass fiber reinforced ABS composite material with excellent performance by microwave in-situ polymerization.

The object of the present invention is implemented like this: styrene monomer is dissolved uncrosslinked butadiene rubber, puts acrylonitrile and initiator dibenzoyl peroxide (BPO) again, makes low-viscosity polymerization through slow stirring Then, the glass fiber cloth treated with silane coupling agent is fully impregnated and put into the mold, and the glass steel plate and stainless steel screw are closed, and heated and pressurized on the microwave heater to make long glass fiber reinforced ABS composite material. The process flow is shown in Figure 1.

The specific implementation process is detailed as follows:

1. Preparation

1) Raw material preparation

Monomer distillation: Use a rotary evaporator to distill styrene monomer and acrylonitrile monomer separately to remove impurities and polymerization inhibitors in the monomer.

Dissolve the rubber into distilled styrene in a certain proportion, and let it stand for 5-6 hours to dissolve the rubber. Then put in a certain amount of distilled acrylonitrile and BPO initiator, and stir slowly with a glass rod. If necessary, if there are too many bubbles, vacuumize for one to five minutes until the solution is clear. The weight ratio of styrene and acrylonitrile is between (6-8):(2-:4), butadiene rubber accounts for 0-10% of the melt weight, and the weight of BPO is 1.0-1.5% of the melt weight.

2) Surface treatment of glass fiber cloth

The main function of the reinforcing material in the composite material is to bear the load and improve the strength or toughness of the composite material. Surface treatment of glass fiber with coupling agent can improve the bonding force between glass fiber and organic resin in the resin composite structure.

Adjust the water to pH 4-5 with acetic acid, then slowly add the silane coupling agent under stirring, the preferred silane coupling agent is KH-550 silane coupling agent, continue stirring until the solution is transparent, and the hydrolysis work is completed. Among them, the chemical name and chemical structural formula of KH-550 are γ-aminopropyltriethoxysilane and [NH ₂ (CH ₂ ) ₃ Si(OC ₂ H ₅ ) ₃ ], respectively.

Adjust the water to a pH value of about 4-5 with acetic acid, then slowly add silane coupling agent accounting for 1-2% of the total water under stirring, and continue stirring until the solution is transparent, and the hydrolysis work is completed. The weight of water is 20 to 60 times greater than the weight of the glass fiber cloth to be treated.

Place the glass fiber cloth that needs to be surface treated in the wetting agent, soak it for 10-15 minutes, then take it out, put it in a container and place it in a drying oven to dry until the glass fiber cloth is dry.

3) Mold preparation

Take white silica gel with a thickness of 5mm, cut it into a rectangular frame structure with an outer frame of 170mm×130mm, an inner frame of 130mm×90mm, with a margin of about 20mm, and paste the mold on the release paper.

4) Preparation of reinforcement materials

Cut the glass fiber cloth that has been surface-treated by the coupling agent into a square with a slightly smaller inner frame size, and weigh the glass fiber cloth. The weight of the glass fiber cloth divided by the weight of the final composite material is the composite material. Glass fiber content in the material.

2. Molding process

Take the upper and lower two glass steel plates that can be fastened with screws on the four sides that are larger than the size of the mold, spread a layer of release paper on the lower glass steel plate, and then place the mold in the center of the glass steel plate. First pour a layer of resin solution evenly in the mold, and then lay the pre-prepared glass fiber cloth inside, so that the solution can soak the glass fiber cloth evenly without leaving air bubbles. Take a piece of release paper and cover it on the fiberglass cloth. Then cover with a glass plate. A thermometer is installed on the surface of the upper glass steel plate. Six stainless steel screws are fastened between the upper and lower two steel plates, and the screws are tightened with a torque wrench to control the pressure during polymerization.

1. Microwave polymerization: put the above mold into a 1000W microwave heater, and radiate heating at a microwave frequency of 2.45GHz. to long extension) to control the temperature of microwave heating. The specific microwave polymerization process is:

The heating temperature is gradually increased in three stages: 80°C-120°C-160°C;

Heating time: 60 minutes per heating section;

The applied pressure of each heating section is: 2MPa-4MPa-6MPa.

2. Thermal polymerization: put the above mold into the oven, the specific thermal polymerization process is:

The heating temperature is gradually increased in three stages: 80°C-120°C-160°C;

The heating time is: three sections are: 3 hours, 2 hours and 3 hours;

The applied pressure of each heating section is: 2MPa-4MPa-6MPa.

The characteristics of the preparation method of the microwave in-situ polymerization long glass fiber reinforced ABS composite material provided by the invention are:

1. Use low-viscosity monomers or prepolymers to infiltrate fibers, with good infiltration, fast infiltration speed, and easy production, which fundamentally solves the difficulty of resin impregnating glass fibers in the production process of long glass fiber reinforced thermoplastic composites. The problem.

2. Since the monomer is used as the raw material instead of the polymer, the polymerization and compounding processes are combined into one, so compared with the existing production process of long glass fiber reinforced thermoplastic composite materials, the process can be greatly reduced and the cost can be saved.

3. Microwave polymerization is fast and efficient.

4. The interface bonding performance of the glass fiber reinforced ABS composite material is good, the distribution of the rubber phase in the resin matrix is uniform and fine, and the mechanical properties are better than those of the in-situ polymerized long glass fiber reinforced ABS composite material thermally polymerized by a flat vulcanizer The mechanical properties are better.

Description of drawings

Fig. 1, microwave in-situ polymerization long glass fiber reinforced ABS composite material process flow chart of the present invention;

Fig. 2, the photograph of the fracture surface of the ABS sample prepared by microwave polymerization and thermal polymerization of the present invention.

In Fig. 2 (a) is a scanning electron microscope fracture photograph of an ABS sample prepared by microwave polymerization, and (b) is a scanning electron microscope fracture photograph of an ABS sample prepared by thermal polymerization.

Detailed ways

The following examples help to understand the present invention, but are not limited to the content of the present invention:

Example 1:

According to the above-mentioned process steps, the long glass fiber reinforced ABS composite material with a butadiene glass fiber content of 46% and a diene rubber content of 7% of the total resin content was prepared. The total polymerization time and main mechanics of microwave polymerization and thermal polymerization were two cases. The performance comparison is shown in Table 1. The thermal polymerization process is at 80°C, the molding time is 4 hours, and then the temperature is increased by 20°C every hour until the temperature rises to 160°C.

Table 1 Comparison of microwave polymerization and thermal polymerization of composite materials with rubber content of 7% total resin content aggregation type Total aggregation time (h) Layer shear strength (MPa) Notched impact strength (J·m ^-1 ) In-situ Microwave Polymerization of Long Fiber Reinforced ABS 3 18.8 676.9 In-situ Thermal Polymerization of Long Glass Fiber Reinforced ABS 8 15.1 587.5

It can be seen from Table 1 that compared with thermal polymerization, the total polymerization time, layer shear strength and notched impact strength of microwave polymerization are 38%, 125% and 115% of thermal polymerization.

Example 2:

A long glass fiber reinforced ABS composite material with a glass fiber content of 52% and a butadiene rubber content of 5% of the total resin content was prepared. The total polymerization time and main mechanical properties of microwave polymerization and thermal polymerization are compared in Table 2 .

Table 2 Comparison of microwave polymerization and thermal polymerization of composite materials with rubber content of 5% total resin content aggregation type Total aggregation time (h) Layer shear strength (MPa) Notched impact strength (J·m ^-1 ) In-situ Microwave Polymerization of Long Glass Fiber Reinforced ABS 3 21.6 638.2 In-situ Thermal Polymerization of Long Glass Fiber Reinforced ABS 8 15.1 633.1

It can be seen from Table 2 that compared with thermal polymerization, the total polymerization time, layer shear strength and notched impact strength of microwave polymerization are 38%, 143% and 101% of thermal polymerization.

Example 3:

A long glass fiber reinforced ABS composite material with a glass fiber content of 58% and a butadiene rubber content of 3% of the total resin content was prepared. The total polymerization time and main mechanical properties of microwave polymerization and thermal polymerization are compared in Table 3 .

Table 3 Comparison of microwave polymerization and thermal polymerization of composite materials with rubber content of 5% total resin content aggregation type Total aggregation time (h) Layer shear strength (MPa) Notched impact strength (J·m ^-1 ) In-situ Microwave Polymerization of Glass Fiber Reinforced ABS 3 24.33 617.1 In-situ Thermal Polymerization of Glass Fiber Reinforced ABS 8 19.20 612.6

It can be seen from Table 3 that compared with thermal polymerization, the total polymerization time, layer shear strength and notched impact strength of microwave polymerization are 38%, 127% and 101% of thermal polymerization.

Example 4:

Table 4 shows the comparison of the total polymerization time and main mechanical properties of the butadiene rubber content of 10% of the total resin content and the glass fiber-free ABS under microwave polymerization and in-situ polymerization.

Table 4 rubber content is the comparison of ABS microwave polymerization and thermal polymerization with resin total content of 10% aggregation type Total aggregation time (h) Tensile strength (MPa) Elongation (%) Microwave polymerized ABS 3 28.66 19.49 heat polymerized ABS 8 18.10 13.65

It can be seen from Table 4 that compared with thermal polymerization, microwave polymerization also greatly improves the performance of the resin matrix.

Example 5:

The microstructure of ABS samples prepared by microwave polymerization and thermal polymerization was observed by scanning electron microscope (SEM). Figure 2 (a) and (b) are the high magnification SEM fracture photos of microwave polymerized ABS and thermal polymerized ABS respectively. The white particles in the photo are the rubber phase. It can be clearly seen from the photos that the rubber phase in microwave polymerized ABS (photo a) is very fine and uniform, while the rubber phase in thermally polymerized ABS (photo b) is coarse and unevenly distributed. Compared with thermal polymerization, microwave polymerization makes the rubber phase distribution in ABS more uniform and fine, which should be an important reason for the better performance of microwave in-situ polymerization ABS composites.

Claims (8)

1. A method for microwave in-situ polymerization of long glass fiber reinforced ABS composite materials, which is characterized in that styrene monomer is dissolved in uncrosslinked butadiene rubber, and then acrylonitrile and initiator dibenzoyl peroxide are added , and slowly stirred to make a low-viscosity polymer monomer solution, and then fully impregnated the low-viscosity polymer monomer solution and the glass fiber cloth treated with the silane coupling agent, then put the layer into the mold, close the glass steel plate, and use Microwave heaters or ovens are heated and pressurized to make long glass fiber reinforced ABS composites. 2. A method for microwave in-situ polymerization of long glass fiber reinforced ABS composite materials as claimed in claim 1, characterized in that the low-viscosity polymer monomer solution is dissolved in rubber into styrene, and then put into propylene Nitrile and initiator dibenzoyl peroxide, stir until the solution is clear, the weight ratio of styrene and acrylonitrile is (8:2) ~ (6:4), butadiene rubber accounts for 0 ~ 10% of the melt weight %, the weight of dibenzoyl peroxide is 1.0-1.5% of the melt weight, and the melt weight is the total weight of styrene, rubber, acrylonitrile and initiator. 3. A method for microwave in-situ polymerization of long glass fiber reinforced ABS composite materials as claimed in claim 1, characterized in that the glass fiber cloth treated with the silane coupling agent is soaked in the sizing agent 10-15 minutes, dry; the wetting agent is acetic acid aqueous solution with pH 4-5 containing gamma-aminopropyltriethoxysilane coupling agent with a total water content of 1-2%. 4. A method for microwave in-situ polymerization of long glass fiber reinforced ABS composite materials as claimed in claim 3, characterized in that the weight of the aqueous solution containing the sizing agent is greater than 20 to 60 times the weight of the glass fiber cloth . 5. A method for microwave in-situ polymerization of long glass fiber reinforced ABS composite materials as claimed in claim 1, characterized in that the mold is a silicone mold pasted on release paper, and a layer of Low-viscosity polymer monomer solution, then lay glass fiber cloth inside, release paper is covered on the glass fiber cloth, and the mold is placed in the upper and lower glass steel plates; the lower glass steel plate is covered with a layer of release paper 6. A method for microwave in-situ polymerization of long glass fiber reinforced ABS composite materials as claimed in claim 1, characterized in that the microwave heating pressure is to put the mold as claimed in claim 5 into a microwave heater Polymerization was carried out in three stages of heating and pressure gradually: 80°C/2MPa, 120°C/4MPa and 160°C/6MPa; each heating stage was 60 minutes. 7. A method for microwave in-situ polymerization of long glass fiber-reinforced ABS composite materials as claimed in claim 1, characterized in that the heating and pressure in the oven are performed by putting the mold described in claim 5 into the oven for heating Thermal polymerization with pressure: gradually increase 80°C/2MPa, 120°C/4MPa and 160°C/6MPa in three stages; the heating and pressure time of each stage are: 3 hours, 2 hours and 3 hours respectively. 8. A method for microwave in-situ polymerization of long glass fiber reinforced ABS composite materials as claimed in claim 2, characterized in that said styrene monomer and acrylonitrile monomer are first distilled to remove impurities in the monomer and inhibitors.

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