CN103341985B - Vacuum-assisted resin diffusion molding method for fiber-reinforced PBT composite material - Google Patents

Abstract

The invention provides a vacuum-assisted resin diffusion molding method for a fiber-reinforced PBT composite material. Attach the catalyst to the fiber cloth; place the fiber reinforced material in the mold pasted with high-temperature release cloth and embedded with high-temperature sealing strip; raise the temperature of the mold to 180-220°C, and the polytetrafluoroethylene heating tube feeds the resin into the pipeline Heat to 180-220°C, heat the CBT resin to 180-220°C with an oil bath; submerge the nozzle of the resin injection pipe into the melted CBT resin, and the CBT resin will be sucked into the mold under vacuum; put the mold at 180-220°C Keep warm for 30 minutes to 1 hour, so that the CBT resin can fully infiltrate the fiber reinforced material. At the same time, the CBT resin ring-opening polymerization crystallizes into high molecular weight PBT. After annealing treatment, the fiber reinforced PBT composite material is obtained by demoulding. The invention is a high-performance, low-cost process, and can be used for the manufacture of thin-walled articles and the production of large-scale composite material components.

Description

Vacuum Assisted Resin Diffusion Molding Method of Fiber Reinforced PBT Composites

technical field

The invention relates to a molding method of fiber-reinforced resin composite material, which is suitable for producing large-scale thermoplastic composite material components with high fiber content.

Background technique

In recent years, the research of continuous fiber reinforced thermoplastic resin matrix composites has been highly valued by aerospace industry and automobile manufacturing industry. Compared with thermosetting resin matrix composites, thermoplastic composites have many important advantages, such as better toughness and impact resistance, short molding cycle, low manufacturing cost, and waste can be recycled. However, due to the characteristics of the molecular structure of thermoplastic composite materials, thermoplastics are solid at room temperature; under heating and melting, the resin melt has a high viscosity (>1000Pa.s), and the melt flow is difficult, making it difficult for the resin to completely infiltrate the fiber. Due to the high viscosity of thermoplastic resins, their melt viscosity is much higher than that of thermosetting resins. Therefore, the preparation of thermoplastic composite materials mainly adopts winding molding, roll forming, pultrusion molding, thermocompression molding, vacuum molding and other molding processes. These molding processes have high molding temperature and molding pressure, high energy consumption, and strict requirements on mold equipment, so the production cost is relatively high, especially limited in the large-scale manufacturing of large components.

Cyclic butylene terephthalate (CBT) functional polymer has a macrocyclic oligoester structure and is a mixture of different low molecular weight cyclic oligomers. Its melt viscosity is extremely low, and it becomes It is a liquid like water (under the same conditions, the viscosity of PBT is about 5000 times that of it). Under the action of tin or titanium catalysts, CBT can undergo ring-opening polymerization to obtain thermoplastic engineering plastics polycyclic butylene terephthalate (PBT). There is no gas release during CBT processing, which is green and environmentally friendly, and can make the finished product have a good surface. The superiority of PBT properties makes fiber-reinforced PBT composites have high strength, impact resistance and recyclability, and has great application potential in the field of thermoplastic composites.

Contents of the invention

The purpose of the present invention is to provide a vacuum-assisted resin diffusion molding method for fiber-reinforced PBT composite materials with simple process, low cost, safety and environmental protection, low energy consumption and high efficiency.

The purpose of the present invention is achieved like this:

1) Attach the catalyst to the fiber cloth;

2) Use a certain thickness of fiber cloth with a catalyst as the fiber reinforcement material, place the fiber reinforcement material in a mold pasted with a high-temperature release cloth and embedded with a high-temperature sealing strip; the mold is connected to a resin injection valve with a valve pipeline and vacuum pipeline;

3) Heating with resistance wire to raise the temperature of the mold to 180-220°C, using a polytetrafluoroethylene heating tube to heat the resin injection pipeline to 180-220°C, and heating the CBT resin to 180-220°C with an oil bath;

4) Submerge the nozzle of the resin injection pipe into the melted CBT resin, open the valve of the injection pipeline, and the CBT resin will be sucked into the mold under the action of vacuum, and close the valve of the injection pipeline when the resin flows out of the vacuum pipeline;

5) Keep the mold at 180-220°C for 30min-1h, so that the CBT resin can fully infiltrate the fiber reinforced material. At the same time, the CBT resin ring-opening polymerization crystallizes into high molecular weight PBT. After annealing treatment, demoulding to obtain fiber-reinforced PBT composite Material.

The present invention may also include:

1. The specific operation of attaching the catalyst to the fiber cloth is as follows: pour the catalyst into the isopropanol solution, stir at 80°C for 10 minutes with a magnetic stirrer to completely dissolve the catalyst, and brush the uniform catalyst solution on the Put it on the fiber cloth or soak the fiber cloth in the catalyst solution with a uniform solution, then take it out, dry it at 130°C for 30 minutes, and turn the fiber cloth over halfway.

2. The fiber cloth is one of glass fiber cloth, basalt fiber cloth or carbon fiber cloth or a composite of at least two of them.

3. The catalyst is a tin catalyst, which is dihydroxybutyl tin chloride.

4. The structural formula of the CBT resin is:

The CBT resin is dried at a temperature of 105° C. for more than 10 hours before use.

5. The specific operation of the annealing treatment is: heating to 230-250° C., stopping heating after 30 minutes at a constant temperature, and naturally cooling to room temperature.

The fiber-reinforced PBT composite material obtained by the molding method of the present invention has been tested, wherein the fiber volume content can reach more than 70%.

By adopting the above technical scheme, the present invention has the following advantages: 1) Compared with the prior art, the present invention applies the vacuum-assisted resin diffusion molding process only applicable to thermosetting composite materials to the production of thermoplastic composite materials, avoiding higher The molding temperature and molding pressure effectively reduce the cost and energy consumption. 2) The catalyst is attached to the fiber cloth in advance, instead of directly adding to the CBT resin, the catalyst and the CBT resin are separated in space, and the CBT resin is polymerized in situ on the fiber cloth. This greatly reduces the injection viscosity of the resin and enhances the infiltration of the resin to the fiber. 3) The forming method has simple process, easy operation, low cost, safety and environmental protection, and high production efficiency. Due to the low viscosity of the resin, this method can be used for the molding of thin-walled fiber-reinforced thermoplastic composites and large-scale fiber-reinforced thermoplastic composite components, which is conducive to popularization and application. 4) The fiber-reinforced PBT composite parts produced by this molding process have high fiber volume content and good mechanical properties of the parts.

Aiming at the characteristic of low viscosity of CBT, the present invention proposes a new preparation process of fiber reinforced PBT composite material, that is, under the condition of vacuum negative pressure, the flow and penetration of resin are used to achieve the fiber fabric reinforcement material in the closed mold cavity. Impregnated, then polymerized and crystallized. Compared with traditional thermoplastic composite molding processes, this is a high-performance, low-cost process, and can be used for the manufacture of thin-walled articles and the production of large-scale composite components.

Description of drawings

Accompanying drawing is the flowchart of the present invention.

Detailed ways

The present invention will be described in more detail below with examples in conjunction with the accompanying drawings.

The technological process of the vacuum-assisted resin diffusion molding method of the fiber-reinforced PBT composite material of the present invention is provided in the accompanying drawings, wherein: 1 is CBT resin, 2 is an oil bath heater, 3 is a heating tetrafluoroethylene pipe, and 4 is a ball valve , 5 is a mould, 6 is a resistance wire, 7 is a resin collector, and 8 is a vacuum pump.

Specific implementation plan one:

The catalyst used is dihydroxybutyl tin chloride PC-4101 produced by Guangzhou Yuansu Chemical Co., Ltd.; the fiber reinforcement used is glass fiber with an area density of 300g/ ^m2 produced by Yixing Fuxing Glass Fiber Co., Ltd. Unidirectional cloth; the CBT resin used is a model of CBT100 produced by Cyclics in the United States, and it is dried in an oven at 105°C for 10 hours before use.

Step 1), attach the catalyst to the glass fiber unidirectional cloth. The specific operation is: pour the catalyst with a mass of 0.6% of the mass injected into the CBT resin into an appropriate amount of isopropanol solution, and use a magnetic stirrer to stir at 80°C for 10 minutes. Dissolve the catalyst completely, brush the solution evenly on the glass fiber cloth, put it in an oven at 130°C, bake for 30 minutes, and turn the glass fiber cloth over halfway.

Step 2), select a flat mold with a cavity thickness of 2 mm, paste high-temperature release cloth in the cavity, embed high-temperature sealing strips, and lay 12 layers of glass fiber unidirectional cloth in sequence, with the laying angle of 0 degrees. Mold, tighten the fastening mold bolts. Connect the resin injection pipeline and the vacuum pipeline with valves on the mold. The resin injection port and the vacuum port of the mold are respectively arranged at two ends of the mould, and the resin injection port is provided with a resin diversion groove.

Step 3) Heat the mold with resistance wire to 190°C, use a polytetrafluoroethylene heating tube to heat the resin injection pipeline to 190°C, and heat the CBT resin to 190°C with an oil bath. Submerge the nozzle of the resin injection pipe into the melted CBT resin, open the valve of the injection pipeline, and the CBT resin will be sucked into the mold under the action of vacuum, and close the valve of the injection pipeline when the resin flows out of the vacuum pipeline. Keep the mold at 190°C for 30 minutes to infiltrate the glass fiber reinforced material with the CBT resin, and at the same time, the ring-opening polymerization of the CBT resin crystallizes into high molecular weight PBT.

Step 4), heat the prepared glass fiber reinforced PBT composite material to 240°C (above the melting point of PBT) for annealing treatment, stop heating after 30 minutes at a constant temperature, naturally cool to room temperature, and demould to obtain a glass fiber with a thickness of 1.86mm Reinforced PBT composite laminates.

In this scheme, the temperature lower than the melting point of PBT is selected to carry out ring-opening polymerization of CBT, and the polymerization reaction and the crystallization process of PBT are carried out at the same time, which is easy to operate and reduces energy consumption. After the CBT is polymerized and crystallized, the prepared glass fiber reinforced PBT composite material is heated to above the melting point of PBT for annealing treatment, so that the crystallization of PBT is more complete, the strength and modulus are improved, and the mechanical properties of the composite material are enhanced. The obtained glass fiber reinforced PBT composite laminate has a fiber volume content of 75%. The resin of the laminate has good wettability to the fibers, no delamination, no internal voids, dry spots and other quality defects, and the appearance quality of the laminate is good.

Specific implementation plan two:

The catalyst used is dihydroxybutyltin chloride PC-4101 produced by Guangzhou Yuansu Chemical Co., Ltd.; the fiber reinforcement used is basalt fiber weaving with an area density of 424g/ ^m2 produced by Sichuan Tuoxin Research Institute Cloth; the CBT resin used is the model CBT100 resin produced by Cyclics Company of the United States, and it was dried in an oven at 105°C for 10 hours before use.

Step 1), attach the catalyst to the basalt fiber woven cloth, the specific operation is: pour the catalyst with a mass of 0.6% of the mass injected into the CBT resin into an appropriate amount of isopropanol solution, and use a magnetic stirrer to stir at 80°C for 10 minutes to make The catalyst is completely dissolved, brush the solution evenly on the fiber cloth, put it in an oven at 130°C, bake for 30 minutes, and turn the fiber woven cloth over halfway.

Step 2) Select a flat mold with a cavity thickness of 4mm, paste a high-temperature release cloth in the cavity, embed a high-temperature sealing strip, cover 20 layers of basalt fiber woven cloth in sequence, close the mold, and tighten the mold bolts. Connect the resin injection pipeline and the vacuum pipeline with valves on the mold. The resin injection port and the vacuum port of the mold are respectively arranged at two ends of the mould, and the resin injection port is provided with a resin diversion groove.

Step 3) Heat the mold with resistance wire to 190°C, use a polytetrafluoroethylene heating tube to heat the resin injection pipeline to 190°C, and heat the CBT resin to 190°C with an oil bath. Submerge the nozzle of the resin injection pipe into the melted CBT resin, open the valve of the injection pipeline, and the CBT resin will be sucked into the mold under the action of vacuum, and close the valve of the injection pipeline when the resin flows out of the vacuum pipeline. The mold was kept at 190°C for 30 minutes to infiltrate the CBT resin into the basalt fiber reinforcement, and at the same time, the ring-opening polymerization of the CBT resin crystallized into high molecular weight PBT.

Step 4), heat the prepared basalt fiber reinforced PBT composite material to 240°C (above the melting point of PBT) for annealing treatment, stop heating after 30 minutes at a constant temperature, cool naturally to room temperature, and demould to obtain a braided basalt with a thickness of 3.86mm Fiber reinforced PBT composites.

In this scheme, the temperature lower than the melting point of PBT is selected to carry out ring-opening polymerization of CBT, and the polymerization reaction and the crystallization process of PBT are carried out at the same time, which is easy to operate and reduces energy consumption. After the CBT is polymerized and crystallized, the prepared fiber-reinforced PBT composite material is heated to above the melting point of PBT for annealing treatment, so that the crystallization of PBT is more complete, the strength and modulus are improved, and the mechanical properties of the composite material are enhanced. The obtained fiber-reinforced PBT composite laminate has a fiber volume content of 70%. The resin of the laminate has good wettability to the fibers, no delamination phenomenon, no internal voids, dry spots and other quality defects, and the appearance quality of the laminate is good. .

Claims (6)

1. a vacuum assisted resin diffusion forming method for fiber reinforcement PBT composite, is characterized in that comprising the steps:

1) catalyst is attached in fiber cloth;

2) with the certain thickness fiber cloth with catalyst for fibre reinforced materials, fibre reinforced materials is placed in and posts High temperature release cloth, be embedded with in the mould of elevated-temperature seal bar; The valvular resin injection pipeline of connecting band and vacuum-pumping pipeline on described mould;

3) with Resistant heating, make mould be warming up to 180 ~ 220 DEG C, with polytetrafluoroethylene (PTFE) heating tube to resin injection pipeline heating to 180 ~ 220 DEG C, the oil bath of CBT resin is heated to 180 ~ 220 DEG C;

4) submerged by the resin injection pipe mouth of pipe in the CBT resin after melting, open filling line valve, CBT resin sucks in mould under vacuum, when having resin to flow out in vacuum-pumping pipeline, closes filling line valve;

5) mould is incubated 30min ~ 1h at 180 ~ 220 DEG C, CBT resin is fully infiltrated fibre reinforced materials, the crystallization of CBT resin ring-opening polymerisation is simultaneously the PBT of HMW, and after carrying out annealing in process, the demoulding obtains fiber reinforcement PBT composite.

2. the vacuum assisted resin diffusion forming method of fiber reinforcement PBT composite according to claim 1, it is characterized in that: the described concrete operations be attached to by catalyst in fiber cloth are: poured into by catalyst in aqueous isopropanol, magnetic stirring apparatus is utilized to stir 10min at 80 DEG C, catalyst is dissolved completely, the catalyst solution brush of dissolution homogeneity is taken out in fiber cloth or in catalyst solution fiber cloth being immersed in dissolution homogeneity again, at 130 DEG C of temperature, dry 30min, midway is fiber cloth turn-over.

3. the vacuum assisted resin diffusion forming method of fiber reinforcement PBT composite according to claim 1, is characterized in that: described fiber cloth is a kind of in glass fabric, basalt fiber cloth or carbon cloth or the wherein compound of at least two kinds.

4. the vacuum assisted resin diffusion forming method of fiber reinforcement PBT composite according to claim 1, is characterized in that: described catalyst is dihydroxy dibutyl tin oxide.

5. the vacuum assisted resin diffusion forming method of fiber reinforcement PBT composite according to claim 1, is characterized in that: the structural formula of described CBT resin is:

Described CBT resin first dries more than 10h before use at 105 DEG C of temperature.

6. the vacuum assisted resin diffusion forming method of fiber reinforcement PBT composite according to claim 1, is characterized in that: the concrete operations of described annealing in process are: be heated to 230 ~ 250 DEG C, stops heating, naturally cool to room temperature after constant temperature 30min.