Production method for extruding foamed polypropylene beads by using carbon dioxide
The production of foamed polypropylene beads through carbon dioxide extrusion method solves the problem of gas escape and narrow temperature during the polypropylene foaming process, realizes the industrial production and cost reduction of foamed polypropylene materials, and expands the scope of application.
Patent Information
- Application Number
- CN202510027188.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-08
- Publication Date
- 2025-04-11
AI Technical Summary
It is impossible to produce foamed polypropylene materials in China in industrialized production. The price of foamed polypropylene abroad is high and the transportation costs are high. It is difficult for gas to escape during the polypropylene foaming process and the temperature range is narrow, resulting in uneven bubble cells and low foaming ratio.
The carbon dioxide extrusion method is used to produce foamed polypropylene beads, combined with a heat exchanger through a twin-screw extruder, control temperature and pressure, use high melt strength polypropylene and high melt strength polyethylene, add flame retardant and foaming agent, and underwater pelletization is formed.
The industrial production of foamed polypropylene materials has been achieved, with high production efficiency and diversified formulas, which overcomes the problem of polypropylene foaming, reduces costs, and expands the application fields.
Smart Images
Figure CN119798853A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of foamed polypropylene granulation, in particular to a production method of foamed polypropylene beads by extruding carbon dioxide. Background Art
[0002] Foamed polypropylene products have excellent shock-absorbing properties, high recovery rate after deformation, good heat resistance, chemical resistance, oil resistance and heat insulation. In addition, they are light in weight and can significantly reduce the weight of items. Foamed polypropylene is also an environmentally friendly material. It is not only recyclable and reusable, but also naturally degradable and will not cause white pollution. Due to its good mechanical properties, excellent heat resistance and environmentally friendly properties, foamed polypropylene is a new generation of foam materials after traditional polystyrene foam, polyurethane foam and polyethylene foam, and has broad application prospects.
[0003] However, at present, almost all polypropylene foam products in China are produced by imported foamed polypropylene. There is no technical method for industrialized production in China, and the price of foreign foamed polypropylene is very high, and the transportation cost is high.
[0004] Although polypropylene foam has good performance and application prospects, it is very difficult to develop polypropylene foam. Polypropylene is a crystalline polymer. It hardly flows below the crystalline melting point, but the melt viscosity decreases sharply above the crystalline melting point. Therefore, the gas generated during the polypropylene foaming process is difficult to be enclosed by the melt. In addition, polypropylene releases a lot of heat when it changes from a molten state to a crystalline state, and it takes a long time to change from a melt to a solid. In addition, polypropylene has a high air permeability and the foaming gas is easy to escape. Therefore, the temperature range suitable for polypropylene foaming is narrow. Therefore, it is difficult to obtain products with uniform and fine bubbles and high foaming ratio.
[0005] In view of the above problems, the inventors proposed a production method of foamed polypropylene beads by extruding carbon dioxide to solve the above problems. Summary of the invention
[0006] In order to solve the above problems, the object of the present invention is to provide a method for producing polypropylene beads expanded by extrusion with carbon dioxide.
[0007] In order to solve the above technical problems, the present invention adopts the following technical solution: a method for producing polypropylene beads by extrusion with carbon dioxide, comprising the following steps:
[0008] S1, feeding 73 parts of polypropylene, 20 parts of highly branched polyethylene, 3 parts of foaming agent, 2 parts of flame retardant and 2 parts of auxiliary agent into a feeding system, and transporting them to an extruder through the feeding system for melt mixing;
[0009] S2. Control the temperature of the extruder. The extrusion temperature of the extruder is gradually reduced from the tail to the head. The melt temperature is controlled by the heat exchanger, the melt pressure is adjusted by the melt pump, and finally the finished product is produced by the underwater pelletizing device.
[0010] Preferably, the extrusion device is a twin-screw extruder.
[0011] Preferably, the polypropylene is a high melt strength polypropylene resin, the highly branched polyethylene is a high melt strength polyethylene, and the foaming agent is nitrogen, carbon dioxide, C 1～6 Alkanes, hydrofluorocarbons, methane halides or C 1～5 Any one of fatty alcohols, the flame retardant is an organic bromine flame retardant.
[0012] Preferably, the underwater pelletizer device is a pelletizing system, which meets the different temperatures and pressures required by different production processes.
[0013] Compared with the prior art, the present invention has the following beneficial effects:
[0014] 1. In the present invention, a special processing technology is adopted to produce foamed polypropylene particles. This production method is simple (one-step method), highly efficient, and has diversified formulations. It fills the technical gap of continuous production of foamed polypropylene materials in China. By adjusting the process, it can overcome the unfavorable factors of polypropylene in the foaming process and successfully produce foamed polypropylene materials.
[0015] 2. In the present invention, the industrialized production of polypropylene foam material will be of great significance to the development of the domestic synthetic resin industry, the expansion of the application field and market consumption of polypropylene foam material, and the development of automobile, packaging, food and environmental protection. As a replacement product of foamed polystyrene, foamed polypropylene has a broad market prospect;
[0016] 3. In the present invention, a new processing technology is adopted to produce foamed polypropylene particles, which has the characteristics of high production efficiency and diversified formulas. By adjusting the process, the partially recovered polypropylene or highly branched polyethylene material can be reused, thereby achieving repeated utilization and saving costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0018] Figure 1The present invention is a flow chart of a method for producing polypropylene beads expanded by extrusion with carbon dioxide. DETAILED DESCRIPTION
[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0020] Example: Figure 1 As shown, the present invention provides a method for producing polypropylene beads by extrusion with carbon dioxide, comprising the following steps:
[0021] S1. Prepare materials, select polypropylene and polyethylene resins with high melt strength, use carbon dioxide as the foaming agent, and use organic bromine flame retardant as the flame retardant;
[0022] S2. Through the weightless multi-component feeding system, the feeding amount of each component is accurately controlled. According to the predetermined production formula, the hourly feeding amount of polypropylene resin is set to 440kg / h, the feeding amount of polyethylene resin is set to 120kg / h, the amount of flame retardant is set to 12kg / h, and the amount of additive is set to 12kg / h;
[0023] S3, setting the working temperature of each part of the twin-screw extruder, dividing the barrel heating device of the twin-screw extruder into 7 heating zones, and setting the working temperatures of each zone to 190°C, 190°C, 195°C, 185°C, 180°C, 175°C, respectively, setting the temperature of the connecting section between the twin-screw extruder and the heat exchanger to 170°C, and setting the temperature of the heat exchanger to 170°C;
[0024] S4. Adjust the pressure of the twin-screw extruder, and then start to inject the foaming agent. The injection amount of the foaming agent butane is 18kg / h. The barrel pressure is maintained by adjusting the speed of the twin-screw extruder to prevent the foaming agent from flowing back. After the foaming agent is injected, the temperature of the twin-screw extruder should be properly adjusted to control the template pressure of the underwater pelletizing device to prevent the possibility that the template pressure is too low, resulting in some nozzles with large resistance not discharging materials during pelletizing;
[0025] S5. Control the underwater pelletizing device, set the vent valve temperature to 170°C, the template temperature to 160°C, the circulating water temperature to 80°C, the circulating water pressure to 8 bar, and the cutter speed to be determined according to the actual pellet production conditions;
[0026] S6. The cut foamed particles are sieved by a vibrating screen, and particles of different sizes are classified and temporarily stored. Finally, the particles of different specifications are transported to the packaging machine through the feeding system for packaging and storage.
[0027] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.
Claims
1. A method for producing polypropylene beads by extrusion with carbon dioxide, characterized in that: The following steps are involved: S1, feeding 73 parts of polypropylene, 20 parts of highly branched polyethylene, 3 parts of foaming agent, 2 parts of flame retardant and 2 parts of auxiliary agent into a feeding system, and transporting them to an extruder through the feeding system for melt mixing; S2. Control the temperature of the extruder. The extrusion temperature of the extruder is gradually reduced from the tail to the head. The melt temperature is controlled by the heat exchanger, the melt pressure is adjusted by the melt pump, and finally the finished product is produced by the underwater pelletizing device.
2. The method for producing polypropylene beads by extrusion foaming with carbon dioxide according to claim 1, characterized in that: The extrusion device adopts a twin-screw extruder.
3. The method for producing polypropylene beads by extrusion foaming with carbon dioxide according to claim 1, characterized in that: The polypropylene is a high melt strength polypropylene resin, the highly branched polyethylene is a high melt strength polyethylene, and the foaming agent is nitrogen, carbon dioxide, C 1～6 Alkanes, hydrofluorocarbons, methane halides or C 1～5 Any one of fatty alcohols, the flame retardant is an organic bromine flame retardant.
4. The method for producing polypropylene beads by extrusion foaming with carbon dioxide according to claim 1, characterized in that: The underwater pelletizer device is a pelletizing system, and the pelletizing system meets the different temperatures and pressures required by different production processes.