CN101066620B - Device and method for preparing foamed olefin polymer products by extrusion method - Google Patents

Abstract

The invention relates to a device and a method for manufacturing a foamed polyethylene or polypropylene product by using an extrusion method and a physical foaming agent. The device comprises a high-speed mixer, an extruder connected with the high-speed mixer, a quantitative pump for adding materials into the extruder, and a traction cutting device at the front part of the extruder, wherein a flat slit-shaped extrusion head is arranged at the head part of the extruder; the method comprises the steps of firstly, uniformly blending olefin polymer plastics and nucleating agents in a high-speed mixer, then, putting the mixture into a foamed plastic extruder, and heating the materials to form a molten material under the combined action of shearing and extrusion of a screw; after the materials are completely melted, adding an anti-shrinkage agent and a foaming agent by using a quantitative pump or only adding the foaming agent and uniformly mixing with the melted materials, and then cooling and decompressing and extruding the melted materials mixed with the anti-shrinkage agent and the foaming agent from a flat seam-shaped forming die of an extruder to form foamed plastics; and cutting the extruded foamed plastic by a traction cutting device after cooling.

Description

Device and method for preparing foamed olefin polymer products by extrusion method

technical field

The invention relates to a device and method for manufacturing foamed olefin polymer products, in particular to a device and method for manufacturing foamed polyethylene or polypropylene products by extrusion method and physical foaming agent.

Background technique

(High) foamed polyethylene is a product made of polyethylene (PE) as the main raw material, adding foaming agent and other processing aids through extrusion processing. Foam products are foamed plastics in which the gas is evenly distributed in the material, so they have the characteristics of high specific strength, light weight, sound absorption, shockproof, etc., and are widely used in the packaging of household appliances, furniture, mechanical parts, electronic instruments, and precision instruments. Due to the high-foaming, closed-cell foam characteristics of high-expansion polyethylene, it has excellent water resistance, heat insulation and good buoyancy. Compared with the traditional packaging material molded foam EPS, high foam polyethylene has the advantages of direct recycling, soft texture and no damage to the surface of the packaged object, and it is not easy to be damaged and used for many times, so it is gradually replacing PS in the field of electrical packaging Foaming materials, and become the main material of the packaging industry. At present, the production of foamed polyethylene at home and abroad adopts the method of producing polyethylene foamed extrusion coils with a single extruder or two extruders with a low boiling point liquid as a foaming agent. The extrusion foaming die is mainly in the shape of a ring, and the foam sheet products with a small thickness and width are produced mainly by changing the outer diameter of the shaping drum, adjusting the gap between the ring dies, and changing the traction speed. It is extruded to produce foamed products with a thickness of only 2.0-7.0mm. Because the thickness of the foamed product produced is small, it cannot meet the needs of the current packaging field.

Contents of the invention

The object of the present invention is to provide a novel production device and a production method thereof in view of the deficiency that the existing foamed olefin polymer production device can only produce foamed olefin polymer products with a small thickness.

The technical scheme of the present invention is: a device for preparing foamed olefin polymer products by extrusion, including a high-speed mixer, an extruder connected with the high-speed mixer, a quantitative pump for adding materials to the extruder, and an extruder. The traction and cutting device at the front of the extruder, the head of the extruder is provided with a flat slit extrusion head.

Preferably, the flat slit-shaped extrusion head includes upper and lower templates with flow channels, and side plates for sealing the templates.

Preferably, the gap between the slit-like openings formed between the upper and lower templates is 0-20mm.

Preferably, a calibrating sleeve is provided between the extrusion head and the traction and cutting device, and the calibrating sleeve is composed of two calibrating plates, on which a cooling water tank is opened and a heating device is provided.

Preferably, two movable inner panels are provided on both sides inside the two sizing plates of the sizing sleeve.

A method for preparing foamed olefin polymer products by extrusion using the above-mentioned device, first blending olefin polymer plastics and nucleating agents uniformly in a high-speed mixer, and then putting the mixture into a foamed plastic extruder , the material becomes a molten material through heating, shearing and extrusion of the screw; after the material is completely melted, use a quantitative pump to add an anti-shrinkage agent and a foaming agent or only add a foaming agent and mix it with the molten material evenly , then the molten material mixed with anti-shrinkage agent and foaming agent is cooled from the flat slit forming die of the extruder, and extruded under reduced pressure to form foamed plastic; the extruded foamed plastic is cooled and passed through the traction cutting device Make a cut.

Preferably, the foamed plastic extruded from the flat slit-shaped molding die of the extruder is cooled or heated through a sizing sleeve.

Preferably, the nucleating agent is citric acid, or talcum powder, or calcium carbonate, or carbon black, or metal powder; the blowing agent is a physical blowing agent, which is chlorofluorocarbons or butane , or carbon dioxide, or nitrogen, or a mixture of several of the above-mentioned substance groups.

Preferably, the temperature of the flat slot forming die of the extruder is 50-180°C.

Preferably, the olefin polymer plastic is polyethylene plastic or polypropylene plastic.

Preferably, the polypropylene plastic is high melt strength polypropylene plastic or modified polypropylene plastic.

The beneficial effects of the present invention are: using the flat slit forming die head with a gap between 0 and 20 mm, and the adjustable gap opening degree of the sizing sleeve at the front end, and at the same time controlling the thickness and density of the foamed product in conjunction with the temperature. Continuous extrusion produces polyethylene or polypropylene plastic high-foaming sheets and profiles, and makes high-foaming products with a thickness of 5-200mm, so as to meet the needs of packaging materials in household appliances, furniture and other fields.

Description of drawings

Fig. 1 is the process flow chart of the specific embodiment of the present invention;

Fig. 2 is the structural representation of the flat slit forming die head of specific embodiment of the present invention;

Fig. 3 is a structural schematic view of another perspective of the flat slit-shaped forming die of a specific embodiment of the present invention;

Fig. 4 is the structural representation of the shaping sleeve of the specific embodiment of the present invention;

Fig. 5 is a structural schematic view of another perspective of the calibrating sleeve according to the specific embodiment of the present invention;

Fig. 6 is another workflow flowchart of the specific embodiment of the present invention.

Detailed ways

As shown in Figures 1 to 5, a specific embodiment of the present invention, a device for preparing foamed polyethylene or polypropylene products by extrusion, comprising a high-speed mixer 1, an extruder 2 connected to the high-speed mixer 1 , a quantitative pump 3 for adding materials into the extruder 2, and a traction cutting device 7 at the front of the extruder 2, the head of the extruder 2 is provided with a flat slit-shaped extrusion head 5. The flat slot-shaped extrusion head 5 includes upper and lower templates 9, 10 with flow channels, and side plates 11, 12 for sealing the templates. The gap between the slit-like openings 4 formed between the upper and lower templates 9, 10 is 0-20mm. A sizing sleeve 6 is arranged between the flat slit extrusion head 5 and the traction and cutting device 7, the sizing sleeve 6 is composed of two sizing plates 13, 14, the sizing plate 6 is provided with a cooling water tank, And is equipped with a heating device. Two movable inner panels are arranged on both sides inside the two sizing plates 13 and 14 of the sizing sleeve 6 . The traction and cutting device is composed of a driving device 15 and two clamping rollers 16. The driving device 15 can be steplessly adjusted in speed. Driven by the driving device 15, the two racking rollers 16 clamp and pull the formed foamed sheet, and perform cutting according to the needs. cutting.

In the first specific embodiment of the production method of the present invention, at first the polyethylene plastic (melt index is 2) and the 2000 mesh talc powder nucleating agent added in an amount of 1.5% are mixed uniformly in the high-speed mixer 1 and then dropped into plastic foaming In the extruder 2, the plastic foaming extruder is a two-stage extrusion system, the first stage is a twin-screw extruder with a diameter of 60mm, and the diameter of the second-stage screw is 150mm, and the material passes through the first-stage twin-screw extruder The extruder is heated, and its temperature is controlled above the melting temperature of polyethylene plastic. Barrel heating temperatures are 120°C, 150°C, 180°C, 180°C respectively. Under the joint action of twin-screw shearing and extrusion, the molten material is plasticized. After the material is completely melted, the quantitative pump 3 is used to add the anti-shrinkage agent, and the addition is 3.5%; the quantitative pump 3 is used to add the blowing agent, and the addition is 12%, and make it mix evenly with the molten material under the action of the twin-screw, the rotating speed of the twin-screw extruder is controlled at 35 rpm, and the evenly mixed material enters the second-stage extruder through the online runner, and passes through Adjust the temperature of the second-stage plastic extrusion foam molding machine. The temperature process condition is that the temperature should gradually drop from the melting temperature of 180°C to 90°C. The screw speed of the plastic extrusion foam molding machine is controlled at 40 rpm. The internal pressure of the plastic extrusion foam molding machine is controlled at 10MPa, the temperature of the molten mixture is controlled at 100°C after passing through the flat slit-shaped die head 5, and the opening of the gap is adjusted to 1.2mm. The molten material is cooled and shaped by the cooling/heating sizing sleeve 6, the width of the opening of the cooling/heating sizing sleeve 6 is 600 mm, and the foamed thickness is 35 mm, the width is 600 mm and the density is 35 kg/m ³ products. Then the foamed sheet material 8 is gripped and drawn by the drawing and cutting device 7, and cut according to the required length.

In the second specific embodiment of the production method of the present invention, at first the polypropylene plastic (melt index is 2) and the 2000 mesh talcum powder nucleating agent added in an amount of 1.5% are mixed uniformly in the high-speed mixer 1 and then put into plastic foaming In extruder 2, the plastic foaming extruder is a two-stage extrusion system. The first stage is a twin-screw extruder with a diameter of 60mm, and the diameter of the second-stage screw is 150mm. The material is extruded through the first-stage twin-screw extruder Machine heating, and its temperature is controlled above the melting temperature of polyethylene plastic. Barrel heating temperatures are 120°C, 150°C, 180°C, 180°C respectively. Under the joint action of twin-screw shearing and extrusion, the molten material is plasticized. When the material is completely melted, the quantitative pump 3 adds foaming agent, and the addition amount is 12%, and it is mixed with the molten material under the action of the twin-screw. The material is mixed evenly, and the speed of the twin-screw extruder is controlled at 40 rpm. The uniformly mixed material enters the second-stage extruder through the online flow channel, and the temperature of the second-stage plastic extrusion foam molding machine is adjusted. The process conditions are that the temperature should be gradually lowered, from the melting temperature of 180 ° C to 90 ° C, the screw speed of the plastic extrusion foam molding machine is controlled at 45 rpm, the internal pressure of the plastic extrusion foam molding machine is controlled at 12 MPa, and the molten mixture After the material passes through the flat slit forming die 5, the temperature is controlled at 90°C, and the opening of the gap is adjusted to 2.2 mm. The material is extruded at the die and released under reduced pressure, and then the molten material is cooled and shaped by the cooling/heating sizing sleeve 6. The width of heating setting cover 6 is 600mm, and height is 120mm. A product with a foamed thickness of 120 mm, a width of 600 mm and a density of 35 kg/m ^was obtained. Then the foamed sheet material 8 is gripped and drawn by the drawing and cutting device 7, and cut according to the required length.

The third embodiment of the production method of the present invention as shown in Figure 6, the extruder is a two-stage extrusion device composed of two extrusion systems, and the first-stage extrusion device is a single-screw or twin-screw extruder . At first polyethylene plastic (melt index is 2) and the talcum powder nucleating agent that addition is 1%, drop in the plastic foaming extruder 2 after blending in high-speed mixer 1, and described plastic foaming is extruded The extruder is a two-stage extrusion system, the diameter of the first-stage screw is 135mm, and the diameter of the second-stage screw is 150mm. The material is heated by the first-stage extruder, and its temperature is controlled above the melting temperature of polyethylene plastic. The heating temperatures were 120°C, 150°C, 180°C, and 180°C, respectively. Under the joint action of shearing and extrusion of the screw, the molten material is plasticized. After the material is completely melted, the anti-shrinkage agent is added with the quantitative pump 3, and the addition is 3%; and the foaming agent is added, and the addition is 8%. And make it mix evenly with the molten material under the action of the screw. The screw speed of the plastic extrusion foam molding machine is controlled at 40 rpm. The evenly mixed material enters the second-stage extruder through the online channel. For the temperature of the second-stage plastic extrusion foam molding machine, the temperature process condition is that the temperature should gradually drop from the melting temperature of 180°C to 90°C, and the screw speed of the plastic extrusion foam molding machine should be controlled at 35 rpm. The internal pressure of the foam molding machine is controlled at 8MPa. The temperature of the molten mixture is controlled at 100°C after passing through the flat slit forming die 5, and the opening of the gap is adjusted to 0.8mm. /Heating the sizing sleeve 6 to cool and shape the molten material, the opening width of the cooling/heating sizing sleeve 6 is 600 mm, and the height is 25 mm. A product with a foamed thickness of 25 mm, a width of 600 mm and a density of 35 kg/m ^was obtained. Then the foamed sheet material 8 is gripped and drawn by the drawing and cutting device 7, and cut according to the required length.

The opening of the sizing sleeve can be adjusted so as to produce foamed plastic products with different widths. The splint is designed as a structure that can move up and down to adjust the height of the opening.

In addition, as in the conventional manufacturing process of foamed plastics, the user can further adjust the thickness of the foamed polyethylene or foamed polypropylene by adjusting the pulling speed of the pulling structure in a conventional way.

The obtained product indicators are as follows:

Foaming ratio Relative density Kg/m³ Thickness range mm Compression deformation % Load Creep %  Instability loadkPa Thermal conductivity w/m k  Buoyancy Kg/m³ Tensile strength kPa Tensile elongation% Tear strength N/mm 5 90～100 5～200 10 1.3 212 0.063 905 481 25 2.9 15 70～80 5～200 12 1.6 126 0.058 925 393 34 2.4 25 40～50 5～200 13 2.5 73 0.059 965 345 67 2.3 35 35～40 5～200 14 2.5 56 0.063 970 294 62 2.0 45 25～30 5～200 14 2.1 49 0.064 975 245 59 1.9

Claims (8)

1. A device for preparing foamed olefin polymer products by extrusion, comprising a high-speed mixer, an extruder connected to the high-speed mixer, a quantitative pump for adding materials to the extruder, and a front part of the extruder The drawing and cutting device is characterized in that: the head of the extruder is provided with a flat slit-shaped extrusion head, and a shaping sleeve is arranged between the extrusion head and the drawing and cutting device, and the shaping The sleeve is composed of two shaped plates, on which there is a cooling water tank and a heating device. 2. The device for preparing foamed olefin polymer products by extrusion as claimed in claim 1, wherein the flat slit-shaped extrusion head comprises upper and lower templates with flow channels, and Side panels for sealing the formwork. 3. The device for preparing foamed olefin polymer products by extrusion method as claimed in claim 2, characterized in that: the gap between the slit-shaped openings formed between the upper and lower die plates is 0-20 mm. 4. The device for preparing foamed olefin polymer products by extrusion method as claimed in claim 1, characterized in that: two movable inner plates are arranged on both sides inside the two sizing plates of the sizing sleeve. 5. A method for preparing foamed olefin polymer products using the extrusion method of the device described in claim 1, first olefin polymer plastics and nucleating agent are blended uniformly in a high-speed mixer, and then the mixture is dropped into foam In the plastic extruder, the material becomes a molten material through the combined action of heating, shearing and extrusion of the screw; after the material is completely melted, the anti-shrinkage agent and foaming agent are added by a quantitative pump or only the foaming agent is added and combined with The molten material is mixed evenly, and the characteristic is that the molten material mixed with anti-shrinkage agent and foaming agent is cooled from the flat slit forming die of the extruder, and extruded under reduced pressure to form continuous polyethylene or polypropylene plastic foam. Foam sheet or profile; the extruded plastic foam sheet or profile is cut by a traction cutting device after cooling; the foamed plastic extruded by the flat slit forming die of the extruder is cooled or heated through a calibrator Styling treatment. 6. Extrusion method as claimed in claim 5 prepares the method for foamed olefin polymer product, it is characterized in that: described nucleating agent is citric acid or talcum powder or calcium carbonate or carbon black or metal Powder; the foaming agent is a physical foaming agent, which is chlorofluorocarbons, or butane, or carbon dioxide, or nitrogen, or a mixture of multiple types of the above-mentioned substance groups. 7. The method for preparing foamed olefin polymer products by extrusion as claimed in claim 5, characterized in that: the temperature of the flat slit forming die of the extruder is 50-180°C. 8. The method for preparing foamed olefin polymer products by extrusion as claimed in claim 6 or 7, is characterized in that: described olefin polymer plastic is polyethylene plastic or polypropylene plastic, and described polypropylene plastic is High melt strength polypropylene plastic or modified polypropylene plastic.

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