CN102126262A - Blade type processing equipment and processing method of plastic and plantfiber composite materials - Google Patents

Abstract

The invention provides blade-type processing equipment and a processing method for plastic and plant fiber composite materials. The blade type processing equipment consists of a group of blade type plastic feeding units that run through the rotor shaft and are connected in sequence, more than one group of odd groups of blade type plastic plasticizing and transporting units, a group of blade type plant fiber feeding units and more than one group of composite Composition of material mixing and transportation unit. A plastic feeding port and a feeding hopper on the feeding port are provided on the upper part of the plastic feeding unit, and a plant fiber metering feeder is provided on the upper part of the plant fiber feeding unit. The axial width ratio of the plant fiber feeding unit to the plastic feeding unit is 1:1~50, using the working volume difference between the two feeding units and the plant fiber metering feeder, the plant fiber and plastic are fed into the blade for plasticization Extrusion processing. The invention can independently and quantitatively introduce plant fibers and uniformly disperse and mix them with plastic substrates, effectively reduce the thermal degradation of plant fibers, maintain the aspect ratio of plant fibers, and improve the performance of composite material products.

Description

Blade-type processing equipment and processing method for plastic and plant fiber composite materials

technical field

The invention relates to a composite material processing method and equipment, in particular to a blade-type processing equipment and method for plastic and plant fiber composite materials

Background technique

For the molding and processing of plastic and plant fiber composite materials, the currently commonly used feeding method is that plant fiber, plastic and other additives are mixed evenly and added together through the feed port, and directly enter the screw extruder or injection machine for processing and molding. There are two main problems in this plant fiber introduction method: (1) During the plasticizing and transporting process, since the plant fiber needs to go through the solid transport, melt plasticization and melt transport process together with the plastic, the plant fiber will be on the metal wall. The friction force of the solid plastic, the extrusion shear force of the solid plastic, the viscous force of the melt, the force between the fibers, etc., cause the fiber length-to-diameter ratio to become smaller, especially for the solid conveying process and the melting process. The destructive effect of fiber is the most serious; (2) because the density of plant fiber and plastic is quite different, the stratification phenomenon of plant fiber and plastic can occur when feeding in the hopper, makes raw material mixing uneven and affects product quality.

Although there is currently a technical solution for setting up a separate feeding port behind the hopper to add fibers separately, but due to the limitations of the traditional screw extrusion conveying structure, there are still many problems such as uneven feeding and a large reduction in the length-to-diameter ratio of the plant fiber forming process. defect. CN200710018210.3 discloses a special conical twin-screw extruder for wood-plastic composite materials. By reasonably arranging the positions of the cooling section and the heating section on the barrel, and improving the exhaust and screw structure, it solves the problem of extrusion of wood-plastic composite materials. Overheating and decomposition of wood powder or other fiber materials, insufficient plasticization of raw materials, uneven mixing of various components of the material, material leakage at the exhaust port, and unstable extrusion process have not been eliminated, but they have not been able to get rid of the traditional screw processing method. Limitations of plastic and plant fiber composites. In traditional screw processing machinery, the plasticizing and transporting of materials mainly depends on the drag effect on the material when the screw rotates. The solid transport is friction drag, and the melt transport is viscous drag. The velocity gradient of the material is perpendicular to its flow and deformation direction. Flow and deformation are governed by shear stress. The forced shear dispersion obtained by the traditional screw plasticizing conveying method will cause the fiber length-to-diameter ratio in the product to be greatly reduced, and it is easy to cause local high temperature to degrade the material. There is a contradiction between forced mixing and low-temperature processing, and the material is plasticized. The defects of long thermomechanical process and high energy consumption during transportation are not conducive to the extrusion molding of plastic and plant fiber composite materials.

ZL200810026054.X discloses a method and equipment for plasticizing and transporting polymer materials based on extensional rheology. The principle is to achieve a polymer with a short thermomechanical history dominated by tensile deformation through periodic changes in the plasticizing transport space. The invention relates to plasticizing transportation, and discloses a plastic processing equipment composed of blade type plasticizing transportation units. However, the disclosed plasticizing transportation method and equipment are provided with only one feeding port, which cannot realize quantitative and uniform addition of plant fibers according to the ratio of plastics and plant fibers, and are not suitable for processing plastics and plant fiber composite materials.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned shortcomings existing in the prior art, and to provide a blade-type processing equipment and processing method for plastic and plant fiber composite materials, so as to solve the problem that the plasticizing capacity of the screw plasticizing transportation mainly depends on materials and metals. The problem of friction between the surface of the barrel and the internal friction of the material is solved, and the separate introduction of plastic and plant fiber is realized.

The vane-type processing equipment for plastic and plant fiber composite materials provided by the present invention consists of a vane-type plastic feeding unit that runs through the rotor shaft and is connected in sequence, more than one set of odd-group vane-type plastic plasticizing and transporting units, and more than one set The composite material mixing and transporting unit is composed of a plastic feeding port on the blade-type plastic feeding unit, a plastic feeding hopper is installed on the plastic feeding port, and a blade-type plant fiber feeding Feeding unit, a plant fiber metering feeder is installed on the blade type plant fiber feeding unit.

The axial width ratio of the vane-type plant fiber feeding unit to the vane-type plastic feeding unit is 1:1-50, and this ratio can be changed according to the ratio range of the composite material to be processed. Since plant fiber with a certain ratio of plastic is added to the blade-type plant fiber feeding unit, the volume of the material in the feed unit increases, so the axial width of the blade-type plant fiber feeding unit needs to be increased. For example, when the volume content of plant fiber in the composite material is 50%, the ratio of the axial width of the vane-type plant fiber feeding unit to the vane-type plastic feeding unit is at least 2. When the fiber content is 90%, the width ratio is at least 10, but considering that the bulk density of plant fibers is relatively small, and the bulk density of different types of plant fibers is not the same, so the width ratio should be increased appropriately. The function of feeding the plant fiber into the blade plasticizing extrusion system is realized by using the working volume difference between the plant fiber feeding unit and the plastic feeding unit and the function of the plant fiber metering feeder.

The blade-type processing equipment for plastic and plant fiber composite materials mentioned above can be used not only as a blade-type extruder for plastic and plant fiber composite materials, but also as a blade-type plastic and plant fiber composite material pre-plasticizing unit combined with a plunger injection unit Plasticizing injection machine.

The present invention also provides a blade-type processing method for plastics and plant fiber composite materials, which is to introduce the polymer material plasticizing and transporting method based on extensional rheology into the processing process of plastics and plant fiber composite materials. The axial width of the blade-type plant fiber feeding unit in the equipment is enlarged, so that its working volume is larger than that of the blade-type plastic feeding unit, and the working volume difference between the two feeding units and the plant fiber metering feeder are used to realize Plant fibers and plastic are fed into the blades for plasticizing and extrusion processing.

The method provided by the present invention is specifically realized through the following scheme: under the drive of the rotor shaft 1, plastics and other additives are brought into the blade-type plastic feeding unit from the plastic feeding port, and because the transportation space changes from large to small Under the action of extrusion force, it enters the vane-type plasticizing and transporting unit. If the plasticizing effect is good after passing through a vane-type plasticizing and transporting unit, blades can be installed after the vane-type plasticizing and transporting unit. type plant fiber feeding unit; if the plastic needs to be further plasticized after passing through a blade-type plastic plasticizing and transporting unit, the melting and plasticizing of the plastic is completed through subsequent groups of even-group blade-type plasticizing and transporting units. This is because the upper part of the transportation unit behind the odd group of vane-type plasticizing transportation units is a suction area with gradually increasing volume, and the blade-type plant fiber feeding port can be opened behind the odd group of blade-type plasticizing transportation units. , and the upper part of the transport unit after the plasticized transport unit of the even number of blades is a pressure zone with a gradually decreasing volume, and the feeding port cannot be opened. Since the blade transport unit has positive displacement characteristics, the ratio of plant fiber to plastic can be controlled by adjusting the feeding speed of the plant fiber metering feeder.

The feature of the present invention is to utilize the effect of the polymer material plasticizing transport method based on extensional rheology, and set up a separate plant fiber feeding port behind the plastic feeding unit, which can realize the independent quantitative introduction of plant fiber and combine with the plastic base material Evenly disperse and mix, and can effectively reduce the thermal degradation of plant fibers, maintain the aspect ratio of plant fibers, thereby improving the performance of composite products, and achieve the purpose of adding plant fibers evenly according to the ratio requirements and better maintaining their aspect ratio. It solves the problem that the plasticizing capacity mainly depends on the friction force between the material and the surface of the metal barrel and the internal friction force of the material during the screw plasticizing transportation process, and realizes the separate introduction of plastic and plant fiber.

Compared with prior art, the present invention has following advantage:

1. The equipment provided by the present invention is to set up a separate plant fiber feeding unit behind the plastic feeding unit, which can independently and quantitatively introduce plant fibers, and overcome the problem of uneven proportioning caused by material layering when fed together by the same hopper.

2. The present invention introduces plant fibers in the state of plastic melting, avoiding the destruction of plant fiber aspect ratio by external force during stirring and mixing in the early stage and solid material conveying process.

3. The plasticizing and transporting process of the present invention is dominated by the tensile force field, and the fibers can be oriented quickly along the direction of the tensile deformation, which is beneficial to the disentanglement of the fiber aggregates and thus has a better dispersion effect; Under the action of the shear flow field, the bending deformation of the flexible fiber occurs during the rotational movement, resulting in the breaking of the fiber, which can maintain the large aspect ratio of the plant fiber, which is more suitable for the preparation of short plant fibers and polymer composite materials, and greatly improves The mechanical properties of the product.

4. The present invention greatly shortens the thermomechanical process experienced in the plasticization and transportation process, reduces the energy consumption of plasticization and transportation, and at the same time greatly reduces the residence time of materials, reducing the probability of material degradation.

5. The forced conveying based on the change of space volume narrows the distribution of thermomechanical history of the material, and the temperature distribution of the material is uniform, which can effectively reduce the processing temperature and reduce the fluctuation of product quality.

6. The present invention utilizes the positive displacement conveying characteristics of the blade conveying unit, so that the plasticizing conveying ability does not depend on the physical properties of the material, and is especially suitable for conveying short plant fibers with low bulk density, thus improving the stability of plasticizing conveying , Improve adaptability to materials.

Description of drawings

Fig. 1 is the structural representation of the vane type extruder of plastics and plant fiber composite material;

Fig. 2 is a schematic structural diagram of a vane-type plasticizing injection machine for plastic and plant fiber composite materials.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and examples, but the protection scope of the present invention is not limited to the range expressed in the examples.

Example 1

Referring to Fig. 1, the vane type extruder of plastic and plant fiber composite material is composed of a group of vane type plastic feeding units 4, a group of vane type plastic plasticizing and transporting units 5, a group of The blade-type plant fiber feeding unit 6 and two groups of composite material mixing and transporting units 7 and 8 are formed. A plastic feeding port is provided on the upper part of the plastic feeding unit, and the plastic feeding hopper 2 is set above the feeding port of the blade type plastic feeding unit 4 . Driven by the rotor shaft 1, plastics and other additives are fed into the blade-type plastic feeding unit 4 from the plastic feeding port, and enter into the blade-type plastic feeding unit 4 under the action of extrusion force due to the change of the transportation space. The transport unit 5 completes the melting and plasticizing of the plastic. Afterwards, the plastic melt enters the vane-type plant fiber feeding unit 6 , and the width of the vane-type plant fiber feeding unit 6 in the axial direction is greater than the width of the vane-type plastic feeding unit 4 in the axial direction. Because the volume of the vane-type plant fiber feeding unit 6 is greater than that of the front vane-type plasticizing and transporting unit 5, the melt pressure is reduced, so the plant fiber can be taken in by the plant fiber feeding port arranged at the corresponding suction area of the unit stator. A plant fiber metering feeder 3 is arranged above the plant fiber feeding port. Since the blade transport unit has positive displacement characteristics, the ratio of plant fiber to plastic can be controlled by adjusting the feeding speed of the plant fiber metering feeder 3 . Finally, the product is obtained by extruding through a die connected to the transition sleeve of the composite material mixing and transporting unit 8, cooling, and shaping.

In addition, the specific ratio of the axial width of the vane-type plant fiber feeding unit to the vane-type plastic feeding unit is adjusted according to the volume ratio of the plant fibers used in the composite material and the bulk density of the plant fibers.

Example 2

Referring to Fig. 2, the blade-type plasticizing injection machine based on plasticized plastic and plant fiber composite material is mainly composed of plastic and plant fiber composite material pre-plasticizing unit 9, plunger injection unit 13 and collector 10, wherein, The plunger injection unit 13 is composed of an injection cylinder 11 and an injection piston 12 . The feed end face of the material collector 10 is fixedly connected to the discharge end face of the plastic and plant fiber composite material pre-plasticizing unit 9, and the discharge end face of the material collector 10 is fixed to the feed end face of the injection barrel 11 of the plunger injection unit. connect. The composite material melt plasticized by the plastic and plant fiber composite material pre-plasticizing unit 9 enters the injection cylinder 11 of the plunger injection unit through the collector 10, and the injection of the plunger injection unit 13 under the pressure of the melt The piston 12 retreats, and when the amount of material stored in the injection barrel 11 reaches the metering value required by the injection product, the plastic and plant fiber composite material pre-plasticizing unit 9 stops plasticizing, and the plasticizing metering process of the injection machine ends. After the injection machine completes the mold filling and pressure maintaining processes, the plastic and plant fiber composite material pre-plasticizing unit 9 starts plasticizing during the product cooling stage, and the injection machine starts a new cycle of product molding.

Claims (4)

1. A blade-type processing equipment for plastic and plant fiber composite materials, which consists of a blade-type plastic feeding unit that runs through the rotor shaft and is connected in sequence, more than one set of odd-group blade-type plastic plasticizing and transporting units, and more than one set Composite material mixing and transporting unit, characterized in that the blade-type plastic feeding unit is provided with a plastic feeding port, a plastic feeding hopper is installed on the plastic feeding port, and the rear end of the blade-type plasticizing and transporting unit is A blade-type plant fiber feeding unit is installed, and a plant fiber metering feeder is installed on the blade-type plant fiber feeding unit. 2. The equipment according to claim 1, characterized in that the axial width ratio of the blade-type plant fiber feeding unit to the blade-type plastic feeding unit is 1:1-50. 3. The device according to claim 1, characterized in that a plunger injection unit is connected to the end of the last group of composite material kneading and transporting units. 4. A method for processing plastics and plant fiber composite materials according to one of claims 1 to 3, characterized in that the axial width of the blade type plant fiber feeding unit is increased to make the plant fiber feeding unit work The volume is larger than the working volume of the blade-type plastic feeding unit. Using the working volume difference between the two feeding units and the plant fiber metering feeder, the plant fiber and plastic are fed into the blade for plasticizing and extrusion processing.

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