An extruder for a three-layer co-extruded pp straw process

Abstract

The utility model provides a kind of extruder of three-layer co-extrusion PP straw process, including inner layer extruder, middle layer extruder, outer layer extruder, three-layer co-extrusion mould and air intake regulating device;Inner layer extruder, middle layer extruder and outer layer extruder are respectively used to provide inner layer PP material, middle layer PP mixed material and outer layer PP material.The utility model provides a kind of extruder of three-layer co-extrusion PP straw process, through the independent speed regulation design of inner layer, middle layer and outer layer extruder and three-layer co-extrusion mould, the uniform extrusion and reliable bonding of ABA or ABC three-layer straw are realized.Middle layer can add 20-60% food-grade calcium carbonate or talcum powder, so that straw plastic consumption is reduced by 20-45%, different specifications of straw can be produced, suitable for a variety of market demand of environmental protection straw manufacturing, with remarkable advantages in environmental protection, economy and practicability, provide important technical support for the green development of PP straw industry.

Description

Technical Field

[0001] This utility model relates to the technical field of straw preparation equipment, specifically an extruder for a three-layer co-extrusion PP straw process. Background Technology

[0002] Polypropylene (PP) straws are widely used in the catering and beverage industries as disposable consumer products. Current PP straw production primarily employs a single-layer extrusion process, where heated PP material is extruded into shape using a single extruder. While this process produces straws with a simple structure and high production efficiency, it consumes a large amount of plastic, making it less environmentally friendly. Furthermore, the performance characteristics of single-layer straws (such as toughness and hardness) are limited by the material's singular nature, making it difficult to reduce costs while maintaining performance. In recent years, some double-layer co-extrusion technologies have been applied to straw production, using two extruders to feed materials separately to form inner and outer layers, thereby improving straw performance.

[0003] However, there is a lack of three-layer co-extrusion ABA or ABC structure straws and extruders. The so-called ABA or ABC structure means that the inner and outer layers are made of pure PP raw materials, with each layer accounting for 10-15% of the thickness. It has the toughness and elasticity of traditional plastic straws. Sometimes the outer layer can be mixed with different color masterbatches to produce straws of different colors. The middle layer, which accounts for 70-80% of the thickness, is a modified material with 20-60% food-grade calcium carbonate or talc added, or a micro-foaming process material. The purpose is to reduce the amount of plastic used, which can significantly reduce the amount of plastic used. Utility Model Content

[0004] The purpose of this invention is to provide an extruder for a three-layer co-extrusion PP straw process, which can realize three-layer co-extrusion, support flexible adjustment of thickness ratio, and meet the requirements for plastic reduction.

[0005] To achieve the above objectives, the present invention proposes the following technical solution: an extruder for a three-layer co-extrusion PP straw process, comprising an inner extruder (1), a middle extruder (2), an outer extruder (3), a three-layer co-extrusion die (4), and an air intake regulating device (5);

[0006] The inner layer extruder (1), the middle layer extruder (2) and the outer layer extruder (3) are respectively used to provide inner layer PP material, middle layer PP mixture material and outer layer PP material, and the thickness ratio of the inner layer, middle layer and outer layer is controlled by the independent speed adjustment of their respective screws;

[0007] The three-layer co-extrusion die (4) includes an inner layer flow channel (7), a middle layer flow channel (8) and an outer layer flow channel (9) connected in sequence, which are respectively connected to the inner layer extruder (1), the middle layer extruder (2) and the outer layer extruder (3), and are used to extrude the inner layer, middle layer and outer layer materials and form a PP straw with an ABA or ABC three-layer structure.

[0008] The air intake regulating device (5) includes an air intake connecting rod and an air volume regulating valve. The air intake connecting rod is installed on the top of the three-layer co-extrusion mold (4) and is used to control the diameter and wall thickness of the suction tube by adjusting the air volume.

[0009] The three-layer co-extrusion die (4) includes a die connecting sleeve (401), an inner extruder connector (402), and an outer extruder connector (403). The die connecting sleeve (401) is connected to the intermediate extruder (2). The inner extruder (1) and the outer extruder (3) are connected to the die connecting sleeve (401) through the inner extruder connector (402) and the outer extruder connector (403), respectively. The die connecting sleeve (401) is designed with useful... The die connecting sleeve (401) comprises an inner die sleeve (404), an outer die sleeve (406), and a middle die sleeve (405) for forming the straw. A die sleeve pressure ring (407) and a perforated plate (408) are also provided on the die connecting sleeve (401). The die sleeve pressure ring is used to fix and press tightly to seal the inner die sleeve (404), middle die sleeve (405), and outer die sleeve (406) within the die connecting sleeve (401), ensuring that each die sleeve remains stable during extrusion and does not shift or loosen. The perforated plate (408) is used for pre-distribution and filtration of the extruded material.

[0010] Furthermore, in this invention, the length-to-diameter ratio of the inner extruder (1) and the outer extruder (3) is 28:1, and the length-to-diameter ratio of the middle extruder (2) is 28:1 or 33:1.

[0011] Furthermore, in this invention, the intermediate layer accounts for 70-80% of the total thickness of the straw, while the inner and outer layers each account for 10-15%.

[0012] Furthermore, in this utility model, the three-layer co-extrusion mold (4) also includes a mold core (6) and a mold sleeve. The mold core (6) is connected to the mold sleeve through an adjustment device to adjust the centering of the mold in order to control the uniformity and straightness of the suction tube wall thickness.

[0013] Furthermore, in this utility model, the inner layer flow channel (7), the middle layer flow channel (8) and the outer layer flow channel (9) are made of alloy steel or mold material, and the flow channel gaps are 0.25mm, 1mm and 0.25mm respectively. The surface of the flow channel is polished to ensure the uniformity of material extrusion.

[0014] Furthermore, in this utility model, the air inlet connecting rod is a stainless steel part with a vent diameter of 5mm, which is fixed to the top of the three-layer co-extrusion mold (4) by thread, and the air volume regulating valve has an adjustment range of 0-3L / min, which is used to control the diameter of the suction tube within the range of 4-12mm.

[0015] Furthermore, in this utility model, the screw speed range of the intermediate layer extruder (2) is 50-100 rpm, and the screw speed range of the inner layer extruder (1) and the outer layer extruder (3) is 20-50 rpm, so as to achieve matching extrusion of inner, intermediate and outer layer materials.

[0016] Furthermore, in this invention, the flow channel temperature of the three-layer co-extrusion mold (4) is controlled at 210-240℃ to ensure the bonding reliability of the inner, middle and outer layer materials.

[0017] Beneficial effects: The technical solution of this application has the following technical effects:

[0018] This utility model provides an extruder for a three-layer co-extrusion process of PP straws. Through independent speed control design of the inner, middle, and outer extruders, and a three-layer co-extrusion die, it achieves uniform extrusion and reliable bonding of ABA or ABC three-layer straws. Sometimes, different color masterbatches can be mixed into the outer layer to produce straws of various colors. The middle layer can contain 20-60% food-grade calcium carbonate or talc, reducing the amount of plastic used in the straw by 20-45%. This allows for the production of straws of various specifications, suitable for manufacturing environmentally friendly straws to meet diverse market demands. It has significant advantages in terms of environmental friendliness, economy, and practicality, providing important technical support for the green development of the PP straw industry.

[0019] It should be understood that all combinations of the foregoing concepts and the additional concepts described in more detail below can be considered as part of the utility model subject matter of this disclosure, provided that such concepts do not contradict each other.

[0020] The foregoing and other aspects, embodiments, and features of the present invention will be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the present invention, such as features and / or beneficial effects of exemplary embodiments, will become apparent from the following description or may be learned through practice of specific embodiments according to the teachings of the present invention. Attached Figure Description

[0021] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the present invention will now be described by way of example and with reference to the accompanying drawings, wherein:

[0022] Figure 1 This is a schematic diagram of the structure of this utility model.

[0023] Figure 2 This is a schematic diagram of the structure of this utility model.

[0024] Figure 3This is a schematic diagram of the structure of the three-layer co-extrusion mold of this utility model.

[0025] In the figure, the meanings of the various reference numerals are as follows: 1. Inner extruder; 2. Intermediate extruder; 3. Outer extruder; 4. Three-layer co-extrusion die; 401. Die connecting sleeve; 402. Inner extruder connector; 403. Outer extruder connector; 404. Inner die sleeve; 405. Intermediate die sleeve; 406. Outer die sleeve; 407. Die sleeve pressure ring; 408. Perforated plate. Detailed Implementation

[0026] To better understand the technical content of this utility model, specific embodiments are described below in conjunction with the accompanying drawings. Various aspects of this utility model are described in this disclosure with reference to the accompanying drawings, which illustrate numerous illustrative embodiments. The embodiments of this disclosure are not necessarily defined to include all aspects of this utility model. It should be understood that the various concepts and embodiments described above, as well as those described in more detail below, can be implemented in any of many ways, because the concepts and embodiments disclosed in this utility model are not limited to any particular implementation. Furthermore, some aspects of this utility model can be used alone or in any suitable combination with other aspects disclosed in this utility model.

[0027] Example 1

[0028] This embodiment uses the three-layer co-extrusion PP straw process of the present invention to produce standard ABA or ABC three-layer PP straws. The inner and outer layers are made of pure PP material, while the middle layer contains food-grade calcium carbonate or talc filler. The extruder includes an inner layer extruder 1, a middle layer extruder 2, an outer layer extruder 3, a three-layer co-extrusion die 4, and an air intake regulating device 5. The specific operation is as follows:

[0029] Raw material preparation: The inner and outer layers are made of pure PP with a melt index of 2.5-3.0 g / 10 min, and the middle layer is made of a mixture of PP and food-grade calcium carbonate.

[0030] Extruder settings: Inner layer extruder 1 screw speed set to 30 rpm, heating temperature controlled at 210–230℃; intermediate layer extruder 2 screw speed set to 70 rpm, heating temperature controlled at 220–235℃; outer layer extruder 3 screw speed set to 35 rpm, heating temperature controlled at 210–230℃. Each extruder has independent speed control to ensure that the thickness ratios of the inner, intermediate, and outer layers are 10%, 80%, and 10%, respectively.

[0031] Die forming: The three-layer co-extrusion die 4 includes an inner layer runner, a middle layer runner, and an outer layer runner. The runner material is stainless steel with a polished surface. The die temperature is controlled at 220-240℃. The die sleeve 406 is adjusted for centering using a six-point bolt adjustment device to control the uniformity of the suction tube wall thickness, with a deviation of less than ±0.05mm.

[0032] Air intake adjustment: The air intake adjustment device 5 uses a stainless steel air intake connecting rod with a vent diameter of 5mm, which is fixed to the top of the mold by threads and connected to an external air pump. The air volume adjustment valve is set to an air volume of 1.5L / min, so that the suction tube diameter is controlled at 6mm and the wall thickness is 0.16mm.

[0033] Cooling and cutting: The extruded straws are cooled in a water cooling tank at a water temperature of 15℃, and then cut into finished straws with a length of 230mm.

[0034] The resulting straw was tested and found that the toughness of the inner and outer layers met food-grade standards. Adding talc to the middle layer reduced the overall plastic usage by 30%. The three layers were firmly bonded, and the defect rate was less than 0.5%. This straw meets the requirements of EU Regulation 10 / 2011 for food contact materials.

[0035] Example 2

[0036] This embodiment uses the extruder of the present invention to produce micro-foamed ABA or ABC three-layer PP straws. The middle layer uses a micro-foaming process to further reduce the amount of plastic used. The equipment structure is the same as in Embodiment 1, and the specific operation is as follows:

[0037] Raw material preparation: The inner and outer layers are made of high-toughness modified PP with a melt index of 2-3.5 g / 10 min, and the middle layer is made of a mixture of PP and food-grade chemical foaming agent.

[0038] Extruder settings: Inner layer extruder 1 screw speed set to 60 rpm, heating temperature controlled at 195℃; middle layer extruder 2 screw speed set to 90 rpm, heating temperature controlled at 205℃; outer layer extruder 3 screw speed set to 60 rpm, heating temperature controlled at 195℃. The speed control thickness ratios for each extruder are 15%, 70%, and 15%.

[0039] Mold forming: The flow channel structure of the three-layer co-extrusion mold 4 is the same as in Example 1, and the mold temperature is controlled at 215℃. The die sleeve 406 is optimized for centering using an adjustment device to ensure that the straightness deviation of the suction tube is less than 0.05mm. The micro-foaming process of the intermediate layer achieves a foaming ratio of 1.3 times, and the density of the intermediate layer is 0.7g / cm³. 3 .

[0040] Air intake adjustment: The air intake adjustment device 5 is set to an air volume of 2.0L / min, so that the diameter of the straw is controlled at 8mm and the wall thickness is 0.17mm.

[0041] Cooling and cutting: The extruded straws are cooled in a water cooling tank at a water temperature of 10℃ and then cut into finished straws with a length of 230mm.

[0042] The resulting straws were tested and found that the micro-foamed intermediate layer reduced the amount of plastic used by 40%. The overall strength and toughness of the straws met the usage requirements, the three layers were bonded together without peeling, and the product defect rate was less than 0.3%. This straw is suitable for market applications with larger diameters and higher environmental protection requirements.

[0043] All standard parts used in this application can be purchased from the market, and can be customized according to the description and drawings. The specific connection methods of each part adopt conventional methods such as bolts, rivets, and welding that are mature in the prior art. The machinery, parts and equipment adopt conventional models in the prior art. The control method is automatic control through a controller. The control circuit of the controller can be implemented by simple programming by those skilled in the art and is common knowledge in the field. Since this application is mainly used to protect mechanical devices, the control method and circuit connection will not be explained in detail in this application.

[0044] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Those skilled in the art to which this invention pertains can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of this invention shall be determined by the claims.

Claims

1. An extruder for a three-layer co-extrusion PP straw process, characterized in that, It includes an outer layer extruder (3), an intermediate layer extruder (2), an inner layer extruder (1), a three-layer co-extrusion die (4), and an air intake regulating device (5); The inner layer extruder (1), the middle layer extruder (2) and the outer layer extruder (3) are respectively used to provide inner layer PP material, middle layer PP mixture material and outer layer PP material, and the thickness ratio of the inner layer, middle layer and outer layer is controlled by the independent speed adjustment of their respective screws; The three-layer co-extrusion die (4) includes an inner layer flow channel (7), a middle layer flow channel (8) and an outer layer flow channel (9) connected in sequence, which are respectively connected to the inner layer extruder (1), the middle layer extruder (2) and the outer layer extruder (3), and are used to extrude the inner layer, middle layer and outer layer materials and form a PP straw with an ABA or ABC three-layer structure. The air intake regulating device (5) includes an air intake connecting rod and an air volume regulating valve. The air intake connecting rod is installed on the top of the three-layer co-extrusion mold (4) and is used to control the diameter and wall thickness of the suction tube by adjusting the air volume.

2. The extruder for a three-layer co-extrusion PP straw process according to claim 1, characterized in that, The length-to-diameter ratio of the outer extruder (3) and the inner extruder (1) is 28:1, and the length-to-diameter ratio of the middle extruder (2) is 28:1 or 33:

1.

3. The extruder for a three-layer co-extrusion PP straw process according to claim 1, characterized in that, The three-layer co-extrusion die (4) includes a die connecting sleeve (401), an inner extruder connector (402), and an outer extruder connector (403). The die connecting sleeve (401) is connected to the intermediate extruder (2). The inner extruder (1) and the outer extruder (3) are connected to the die connecting sleeve (401) through the inner extruder connector (402) and the outer extruder connector (403), respectively. The die connecting sleeve (401) is designed with an inner die sleeve (404), an outer die sleeve (406), and an intermediate die sleeve (405) for straw forming. The die connecting sleeve (401) is also provided with a die sleeve pressure ring (407) and a perforated plate (408).

4. The extruder for a three-layer co-extrusion PP straw process according to claim 1, characterized in that, The middle layer accounts for 70-80% of the total thickness of the straw, while the inner and outer layers each account for 10-15%.

5. The extruder for a three-layer co-extrusion PP straw process according to claim 1, characterized in that, The three-layer co-extrusion die (4) also includes a die core (6) and a die sleeve. The die core (6) is connected to the die sleeve through an adjustment device to adjust the centering of the die in order to control the uniformity and straightness of the suction tube wall thickness.

6. The extruder for a three-layer co-extrusion PP straw process according to claim 1, characterized in that, The inner flow channel (7), middle flow channel (8) and outer flow channel (9) are made of alloy steel or mold steel, with flow channel gaps of 0.25 mm, 1 mm and 0.25 mm respectively, and the surface of the flow channel is polished to ensure the uniformity of material extrusion.

7. The extruder for a three-layer co-extrusion PP straw process according to claim 1, characterized in that, The air intake connecting rod is a stainless steel part with an air intake hole diameter of 5mm, which is fixed to the top of the three-layer co-extrusion mold (4) by thread. The air volume regulating valve has an adjustment range of 0-3L / min and is used to control the suction tube diameter within the range of 4-12mm.

8. The extruder for a three-layer co-extrusion PP straw process according to claim 1, characterized in that, The screw speed range of the intermediate layer extruder (2) is 50-100 rpm, and the screw speed range of the inner layer extruder (1) and the outer layer extruder (3) is 20-50 rpm, so as to achieve matching extrusion of inner, intermediate and outer layer materials.

9. The extruder for a three-layer co-extrusion PP straw process according to claim 1, characterized in that, The flow channel temperature of the three-layer co-extrusion die (4) is controlled at 210-240℃ to ensure the bonding reliability of the inner, middle and outer layer materials.

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