Multi-layer co-extruded blown film production plant
The multi-layer co-extruded blown film production line addresses weldability challenges by structurally modifying the film production process to allow easy welding of PA layers, ensuring films retain desirable properties for greenhouse use.
Patent Information
- Application Number
- DE202024105887
- Authority / Receiving Office
- DE · DE
- Patent Type
- Utility models
- Current Assignee / Owner
- Priority Date
- 2024-02-19
- Filing Date
- 2024-10-14
- Publication Date
- 2024-12-12
- Estimated Expiration
- 2034-10-31
AI Technical Summary
Agricultural films with PA material on both sides face challenges in width limitations and poor weldability, limiting their use as greenhouse films due to high melting point and long heat sealing times, making them unsuitable for automatic machine welding.
A multi-layer co-extruded blown film production line with specific structural modifications, including annular material exit gap cavities and horizontal vortex flow channels, allows for the outermost and innermost layers to be partially absent, enabling easy welding of PA layers, and uses filler pieces that stabilize the flow without additional fastening measures.
The solution enables easy welding of PA layers, maintaining self-cleaning, mechanical, and thermal insulation properties while overcoming weldability issues, making the film suitable for greenhouse applications.
Smart Images
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Abstract
Description
Technical area
[0001] The present utility model belongs to the technical field of production and processing plants for plastic films as well as production and processing technology and relates in particular to a multi-layer coextruded blown film production plant. Background technology
[0002] The multi-layer coextruded blown film production line is designed to coextrude multiple layers of molten plastic materials to form a plastic film bubble with a multi-layer composite structure. The multi-layer coextruded blown film production line includes a film blowing machine head, the film blowing machine head being equipped with an annular extrusion outlet, an annular converging flow channel, and multiple sets of material spreading channels. Each set of material spreading channels directs the flow of a layer of molten plastic material (referred to as molten material) and spreads the layer of molten material into a ring shape. The downstream end of each set of material spreading channels is connected to the annular converging flow channel, and the annular converging flow channel is connected to the annular extrusion outlet.
[0003] During the operation of the multi-layer co-extruded blown film production line, the extruder melts various plastic raw materials into molten materials and forces them into the blown film head. The corresponding set of material spreading channels for various molten materials in the film blowing machine head gradually expands along the circumferential direction of the film blowing machine head, forming a circular ring. Afterward, the various molten materials merge in the annular converging flow channel and flow together to be extruded through the annular extrusion outlet, forming a multi-layer cylindrical composite film bubble. The cylindrical film bubble is then cut longitudinally (i.e., in a direction parallel to the central axis of the film bubble) to obtain a sheet-like plastic film.
[0004] In order to spread the molten material into a circular shape, the material spreading channel of the film blowing machine head mainly has two structural forms: the first structural form takes the form of a spiral groove flow channel and the second structural form takes the form of a horizontal vortex flow channel.
[0005] The internal structure and the functional principle of the first structural form (spiral groove flow channel form) are described in the Fig. 1 and Fig. 2. It is provided with multiple layers of sleeves 82 arranged concentrically inside and out. The sleeves 82 of each layer have a cylindrical shape. An annular gap 80 is formed between the peripheral sides of each inner and outer adjacent sleeve 82. The lower end of the annular gap 80 is connected to the circular converging flow channel; on the surface of the annular gap between each inner and outer adjacent sleeve 82, a plurality of spiral groove flow channels 81 are formed, each spiral groove flow channel 81 being evenly distributed along the circumferential direction of the sleeve. During the production process, the molten high-temperature material rotates and rises along each spiral groove flow channel 81.During the process of rotating and rising along the spiral groove flow channel 81, the molten material continues to leak upward from the annular gap 80 between every two sleeve layers (that is, it escapes from the spiral groove flow channel 81 and flows upward into the annular gap 80 between the two layers. Therefore, it is called leakage flow), as shown by the arrow in . Fig. 2. In this way, the molten material is gradually spread along the circumferential direction of the film blowing machine head to form a ring shape, then flow into the annular converging flow channel 16, and finally extruded from the annular extrusion outlet 15.
[0006] The internal structure and the functional principle of the second structural form (horizontal vortex flow channel form) are described in the Fig. 3, Fig. 4, Fig. 5 and Fig. 6. It is provided with modules 72 stacked upwards and downwards. A vertical gap is provided between the upper and lower modules 72. The vertical gap is formed into a circular material discharge slot cavity 70 (“circular shape” means that the horizontal projection shape is circular, and because the space cavity is flat and thin and looks like a slit, it is called a “slot cavity”). Furthermore, a plurality of horizontal vortex flow channels 71 are formed on the surface of the material discharge slot cavity 70, and each horizontal vortex flow channel 71 is evenly distributed along the circumferential direction of the film blowing machine head. The edge of one side of the material discharge slot cavity (near the central axis of the film blowing machine head, as shown in Fig. 3, i.e. the inside) is connected to the annular converging flow channel. The edge of the other side of the material outlet slot cavity (away from the center axis of the film blowing machine head, as shown in Fig. 3, i.e., the outside) is closed. During the manufacturing process, the molten high-temperature material flows along each horizontal vortex flow channel 71. During the flow process along the horizontal vortex flow channel 71, the molten material continues to leak from the horizontal vortex flow channel 71 into the material outlet slot cavity 70 (i.e., it exits the horizontal vortex flow channel 71 and flows into the vertical gap between the upper and lower modules 72. Therefore, it is referred to as leakage flow). As indicated by the arrow in Fig. 5, the molten material gradually spreads along the circumferential direction of the material discharge slot cavity 70 to form a ring shape and then flows into the annular converging flow channel 16. The number of horizontal vortex flow channels 71 on the surface of each material discharge slot cavity 70 may be four, eight, sixteen, etc. In the Fig. 5 and Fig. 4 For the sake of simplicity, only four are shown.
[0007] From the perspective of the horizontal projection form, if the above-mentioned "horizontal vortex flow channel" is placed in a plane polar coordinate system, the projection point of the central axis of the film blowing machine head is the center of the polar coordinates, and the forward flow direction of the molten material in this flow channel is the direction in which the polar angle increases, the polar diameter of the flow channel continues to decrease or increase with the increase of the polar angle. This flow channel forms a spiral shape and is therefore called a "vortex flow channel"; and because the "vortex flow channel" is on the horizontal plane, it is called a "horizontal vortex flow channel." If the polar diameter of the flow channel decreases with the increase of the polar angle, as shown in the Fig. 3, Fig. 4 and Fig. As shown in Figure 5, its starting point 710 is located at the outer edge of the material exit slot cavity 70, and the molten material continues to approach the inner side during the feed process in the horizontal vortex flow channel 71. Therefore, it is called an "internally rotating horizontal vortex flow channel"; in contrast, if the polar diameter of the flow channel increases with increasing polar angle, it is called an "externally rotating horizontal vortex flow channel." As in the externally rotating horizontal vortex flow channel 11 in Fig. 6, the starting point 110 is located at the inner edge of the material discharge slot cavity 10, and the molten material continues to approach the outside during the feeding process in the externally rotating horizontal vortex flow channel 11; The outer edge of the material discharge slot cavity corresponding to the externally rotating horizontal vortex flow channel 11 is connected to the annular converging flow channel 16, and its inner edge is closed.
[0008] In the prior art, the modules of the second structural form (horizontal vortex flow channel form) are stacked in multiple layers, and each module is located either inside the annular converging flow channel or on the side of the annular converging flow channel. On the outside, that is, in the same multi-layer coextruded blown film production line, the horizontal vortex flow channels are either internally rotating or externally rotating.
[0009] The film produced by blown film production equipment can be used as agricultural film. Agricultural film is divided into mulch film and greenhouse film. The structure of the multi-layer composite agricultural film can consist of five or seven layers, among which the plastic layer on the surface of the agricultural film is called the surface layer. Since the surface of the agricultural film has two sides (i.e., a top side and a bottom side), it has two surface layers, corresponding to the innermost layer and the outermost layer in the uncut cylindrical film bubble shape.
[0010] In recent years, agricultural films with double-sided surface layers made of PA (polyamide) material have been developed. The performance of this agricultural film is even better than before. Its advantages are as follows: first, the PA material has good self-cleaning properties and is dustproof, which ensures the light transmittance of the film after long-term use; second, the greenhouse film made of PA material has good mechanical properties, which can extend the service life of the greenhouse film by about two years (compared with polyethylene greenhouse film); third, the gas barrier properties of PA material are better than those of polyethylene greenhouse film, and the thermal insulation effect is better, which has a positive impact on plant production in the greenhouse.
[0011] However, agricultural films whose surface layers on both sides are made of PA material (polyamide) have the following problems: Generally, the required width for greenhouse film often exceeds ten meters, and the width of a single piece of agricultural film obtained by film blowing can only be equivalent to 3.14 times the diameter of the film bubble after inflation. However, the diameter of the film bubble (after inflation) containing PA material on both sides is limited by various factors and generally rarely exceeds about 10 meters. Therefore, when the plastic film obtained by film blowing is used as agricultural greenhouse film, multiple plastic films must be welded together in the transverse direction one after the other. However, PA (polyamide) material has a high melting point, a long heat-sealing time, poor welding performance, and is not suitable for automatic machine welding.Therefore, despite many of the excellent properties mentioned above, the aforementioned films, whose double-sided surface layers are made of PA material, are currently used in most cases only as mulch films. There are still difficulties in promoting its use as greenhouse film, which has become a bottleneck. Contents of the utility model
[0012] The purpose of the present utility model is to overcome the above-mentioned deficiencies and provide a multi-layer coextruded blown film production line. The outermost plastic layer and the innermost plastic layer of the resulting film bubbles are partially removed to meet special requirements such as welding.
[0013] Its purpose can be achieved according to the following scheme: a multi-layer coextruded blown film production line configured to coextrude multiple layers of molten materials to form a plastic film bubble having a multi-layer composite structure, the multi-layer coextruded blown film production line comprising a film blowing machine head, the film blowing machine head being equipped with an annular extrusion outlet, an annular converging flow channel, and a plurality of sets of material spreading channels, each set of material spreading channels directing the flow of a layer of molten material and spreading the layer of molten material into a ring shape, the downstream end of each set of material spreading channels being connected to the annular converging flow channel,and the annular converging flow channel is connected to the annular extrusion outlet;, wherein the material spreading flow channel corresponding to the outermost layer of molten material comprises an annular outermost material exit gap cavity, the outermost material exit gap cavity being vertically joined by an annular outer upper module and an annular outer lower module, the outer upper module being located above the outer lower module, and a vertical gap being located between the inner parts of the outer upper module and the inner parts of the outer lower module, the vertical gap forming the outermost material exit gap cavity, the outer edge of the outermost material exit gap cavity being closed, and the inner edge of the outermost material exit gap cavity being connected to the annular converging flow channel; wherein a plurality of internally rotating horizontal vortex flow channels are formed on the surface of the outermost material exit slot cavity; wherein the proximal portion of the outermost material exit slot cavity has a taper that is smaller towards the top and larger towards the bottom, wherein the part of the outermost material exit slot cavity that is not the proximal portion is referred to as the main portion of the outermost material exit slot cavity; wherein the outermost material exit slot cavity is provided with a first filler piece, wherein the first filler piece comprises an inclined portion of the first filler piece and a horizontal portion of the first filler piece, which are designed as a single piece, wherein the inclined portion of the first filler piece is arranged in a proximal portion of the outermost material exit slot cavity and the horizontal portion of the first filler piece is arranged in the main portion of the outermost material exit slot cavity; wherein the material spreading flow channel corresponding to the innermost layer of molten material comprises an annular innermost material exit slot cavity, wherein the innermost material exit slot cavity is vertically joined by an annular inner upper module and an annular inner lower module, wherein the inner upper module is located above the inner lower module, wherein the outer lower module is located at the outer edge of the inner lower module, and the outer upper module is located at the outer edge of the inner upper module; wherein a vertical gap is located between the outer part of the inner upper module and the outer part of the inner lower module, wherein the vertical gap forms the innermost material exit slot cavity; wherein the outer edge of the innermost material exit slot cavity is connected to the annular converging flow channel, and the inner edge of the innermost material exit slot cavity is closed;wherein a plurality of externally rotating horizontal vortex flow channels are formed on the surface of the innermost material exit slot cavity; wherein the distal portion of the outermost material outlet slot cavity has a larger taper towards the top and a smaller taper towards the bottom, wherein the part of the outermost material outlet slot cavity which is not the distal portion is referred to as the main portion of the innermost material outlet slot cavity; wherein the outermost material outlet slot cavity is provided with a second filler piece, wherein the second filler comprises an inclined second filler portion and a horizontal second filler portion formed as a single piece, the inclined second filler portion being disposed in a distal portion of the innermost material exit slot cavity and the horizontal second filler portion being disposed in the main portion of the innermost material exit slot cavity; the second filler and the first filler having the same orientation relative to the central axis of the film blowing machine head.
[0014] The first filler piece has a circumference dimension of 8 to 30 cm and the second filler piece has a circumference dimension of 8 to 30 cm.
[0015] The multi-layer coextruded blown film production line is a seven-layer coextrusion blown film production line; further provided between the annular inner sub-module and the annular outer sub-module are a first sleeve, a second sleeve, a third sleeve, and a fourth sleeve in sequence from the inside to the outside, wherein the inner sub-module, the first sleeve, the second sleeve, the third sleeve, the fourth sleeve, and the outer sub-module are collectively referred to as sleeves, the vertical center axis position of each sleeve being the same, the upper end surfaces of the first and second sleeves having a reverse taper that is larger toward the top and smaller toward the bottom, while the upper end surfaces of the third and fourth sleeves have a positive taper that is smaller toward the top and larger toward the bottom;and an annular gap is formed between each inner and outer adjacent sleeve, and a plurality of spiral groove flow channels are formed on the surface of the annular gap between each inner and outer adjacent sleeve, wherein the annular gap and the spiral groove flow channel form a material spreading flow channel for a layer of molten material between each two adjacent sleeve layers; The annular converging flow channel includes an annular vertical converging flow channel, an annular positive conical converging flow channel, and an annular inverted conical converging flow channel, wherein the annular vertical converging flow channel, the annular positive conical converging flow channel, and the annular inverted conical converging flow channel form an inverted Y-shape in radial cross-section; the annular inverted converging flow channel is formed by the annular gap between the lower part of the inner upper module and the upper end surface of the second sleeve; the annular positive conical converging flow channel is formed by the annular gap between the lower part of the outer upper module and the upper end surface of the third sleeve;there is a radial gap between the upper part of the outer upper module and the upper part of the inner upper module, the radial gap forming part of the annular vertical converging flow channel; The outer edge of the innermost material outlet slot cavity is directly connected to the lower end of the annular inverted converging flow channel, the upper end of the annular gap between the inner sub-module and the first sleeve being directly connected to the lower end of the annular inverted converging flow channel, the upper end of the annular gap between the first sleeve and the second sleeve being directly connected to the lower end of the annular inverted converging flow channel, the upper end of the annular gap between the second sleeve and the third sleeve being connected to the lower end of the annular vertical converging flow channel, and the upper end of the annular gap between the third sleeve and the fourth sleeve being directly connected to the lower end of the annular positive converging flow channel.wherein the upper end of the annular gap between the fourth sleeve and the outer sub-module is directly connected to the lower end of the annular positive conical converging flow channel, wherein the inner edge of the outermost material exit slot cavity is directly connected to the lower end of the annular positive conical converging flow channel.,
[0016] An outer connection module is further provided above the outer top module, and an inner connection module is further provided above the inner top module, wherein a radial gap is located between the outer connection module and the inner connection module, which forms an upper portion of an annular vertical converging flow channel, while the radial gap between the upper part of the outer top module and the upper part of the inner top module forms a lower portion of the annular vertical converging flow channel.
[0017] The present utility model has the following advantages and effects: I. The present utility model can produce a bubble film with a multi-layer plastic composite structure in which the outermost plastic layer is missing in the direction corresponding to the first filler and the innermost plastic layer is partially missing in the direction corresponding to the second filler to meet specific needs. Furthermore, if the outermost plastic layer and the innermost plastic layer are both made of polyamide, the plastic film obtained by cutting the bubble film along the missing part of the polyamide material can be easily welded.The thus obtained multilayer composite film not only retains the advantages of good self-cleaning properties, good mechanical properties and good thermal insulation properties of the polyamide layer, but also avoids the disadvantages of difficult weldability of polyamide and is suitable for advertising and application as agricultural greenhouse films. II. The material spreading channels corresponding to the outermost layer of molten material and the innermost layer of molten material take the form of horizontal vortex flow channels. This means that the corresponding modules are stacked up and down, and the distal section of the innermost material outlet slot cavity has a larger taper towards the top and smaller taper towards the bottom, while the proximal section of the outermost material outlet slot cavity has a smaller taper towards the top and larger taper towards the bottom. The first (second) inclined section of the filler is located within the tapered section of the material outlet slot cavity, and the first (second) horizontal section of the filler is located within the main section of the material outlet slot cavity. This structure also brings the following advantages: 1. After the filler piece is installed, the filler piece can withstand the extrusion pressure without any additional reinforcement measures (for example, thread locking measures or clamping measures are eliminated by concave and convex fits embedded in the surface of the flow channel); 2. The filler requires no additional fastening measures during installation. Especially when the upper module is not yet installed (meaning the upper and lower modules have not yet been able to clamp and fix the filler), the filler can also be stably placed on top of the lower module without moving or falling off. After that, the upper module is installed on the filler, making the filler installation process simple. 3. If necessary, the filler can be removed to produce ordinary film bubbles, which do not require partial material removal from the surface layer. Furthermore, the filler does not require additional fastening measures, meaning the flow channel surface remains smooth after the filler is removed. (In other words, if the installation of the filler requires thread locking measures or clamping measures due to concave and convex fits, the removal of the filler will inevitably result in partial unevenness of the flow channel surface, resulting in poor flow of the molten material on the uneven local surface. This, in turn, can lead to problems such as crystallization, decomposition, and even scorching.) Figures Fig. 1 is a schematic diagram of a sectional structure of a conventional blown film machine head in the form of a spiral groove flow channel. Fig. Figure 2 is a schematic diagram of the working principle of the spiral groove flow channel of a blown film machine head. Fig. Figure 3 is a schematic diagram of a sectional structure of a conventional blown film machine head in the form of an internally rotating horizontal vortex flow channel. Fig. Figure 4 is a schematic diagram of the three-dimensional structure of one of the Fig. 3 modules shown. Fig. 5 is a schematic diagram of a horizontal projection structure of the Fig. 4 shown module. Fig. Figure 6 is a schematic diagram of a horizontally projected structure of a module in the form of an externally rotating horizontal vortex flow channel. Fig. 7 is a schematic diagram of a sectional structure of a specific embodiment of the utility model. Fig. 8 is a partially enlarged schematic diagram of the upper left corner of the drawing area of Fig. 7. Fig. 9 is a simplified schematic diagram of the Fig. Structure shown in Figure 8. Fig. Figure 10 is a partially enlarged schematic diagram of A in Fig. 7. Fig. Figure 11 is a schematic diagram of the horizontal projected position of the first filler piece and the second filler piece in Fig. 7 in the entire blown film machine head. Fig. 12 is a schematic diagram of the three-dimensional shape of the first filler piece. Fig. Figure 13 is a schematic diagram of the horizontally projected shape of the first filler piece. Fig. 14 is a schematic diagram of the lateral shape of the second filler piece. Specific embodimentsEmbodiment I
[0018] One in the Fig. 7, Fig. 8 and Fig. The seven-layer coextrusion blown film production line shown in Figure 9 is configured to coextrude seven layers of molten plastic materials to form a plastic film bubble having a seven-layer composite structure. It comprises a film blowing machine head, the film blowing machine head being equipped with an annular extrusion outlet 15, an annular converging flow channel, and seven sets of material spreading channels. Each set of material spreading channels directs the flow of a layer of molten material and spreads the layer of molten material into a ring shape. The downstream end of each set of material spreading channels is connected to the annular converging flow channel, and the annular converging flow channel is connected to the annular extrusion outlet 15. as in the Fig. 7, Fig. 8, Fig. 9 and Fig. 10, the material spreading flow channel corresponding to the outermost layer of molten material comprises an annular outermost material exit gap cavity 70, the outermost material exit gap cavity 70 being vertically joined by an annular outer upper module 8 and an annular outer lower module 6, the outer upper module 8 being located above the outer lower module 6, and a vertical gap being located between the inner parts of the outer upper module 8 and the inner parts of the outer lower module 6, the vertical gap forming the outermost material exit gap cavity 70; the outer edge (the edge of the annulus where point B in Fig. 9) of the outermost material exit gap cavity 70 is closed, and the inner edge (the edge of the circular ring where point D in Fig. 9) of the outermost material outlet slot cavity 70 is connected to the annular converging flow channel; a plurality of internally rotating horizontal vortex flow channels 71 are formed on the surface of the outermost material outlet slot cavity 70; each internally rotating horizontal vortex flow channel 71 is evenly distributed along the circumferential direction of the film blowing machine head, and the shape and structure of the internally rotating horizontal vortex flow channel is in the Fig. 4 and Fig. 5 to see; the proximal section 702 (section CD in Fig. 9) of the outermost material exit slot cavity has a smaller taper towards the top and a larger taper towards the bottom, with the part of the outermost material exit slot cavity which is not the proximal section being referred to as the main section 701 (section BC in Fig. 9) of the outermost material exit slot cavity; as shown in the Fig. 7 and Fig. 10, the outermost material outlet slot cavity 70 is provided with a first filler piece 91, the shape of the first filler piece 91 in the Fig. 12 and Fig. 13, the circumferential size of the first filler piece 91 is 20 cm, the first filler piece 91 comprises an inclined first filler piece portion 912 and a horizontal first filler piece portion 911 which are formed as one piece, the inclined first filler piece portion 912 being arranged in a proximal portion 702 of the outermost material exit slot cavity and the horizontal first filler piece portion 911 being arranged in the main portion 701 of the outermost material exit slot cavity, as shown in the Fig. 11, Fig. 10 and Fig. 7 shown; as in the Fig. 7, Fig. 8, Fig. 9 and Fig. 10, the material spreading flow channel corresponding to the innermost layer of molten material comprises an annular innermost material exit slot cavity 10, wherein the innermost material exit slot cavity 10 is vertically joined by an annular inner upper module 7 and an annular inner lower module 5, wherein the inner upper module 7 is located above the inner lower module 5, the outer lower module 6 is located at the outer edge of the inner lower module 5, and the outer upper module 8 is located at the outer edge of the inner upper module 7; a vertical gap is located between the outer part of the inner upper module 7 and the outer part of the inner lower module 5, wherein the vertical gap forms the innermost material exit slot cavity 10; the outer edge (the edge of the annulus at which the point E in Fig. 9) of the innermost material exit gap cavity 10 is connected to the annular converging flow channel, and the inner edge (the edge of the annulus where the point G in Fig. 9) of the innermost material outlet slot cavity 10 is closed; a plurality of externally rotating horizontal vortex flow channels 11 are formed on the surface of the innermost material outlet slot cavity; each externally rotating horizontal vortex flow channel 11 is evenly distributed along the circumferential direction of the film blowing machine head, and the shape and structure of the externally rotating horizontal vortex flow channel is in Fig. 6 to see; the distal section 102 (section EF in Fig. 9) of the innermost material outlet slot cavity has a larger taper towards the top and a smaller taper towards the bottom, with the part of the innermost material outlet slot cavity which is not the distal section being referred to as the main section 101 (section FG in Fig. 9) of the innermost material outlet slot cavity; the innermost material outlet slot cavity 10 is provided with a second filler piece 92, the second filler piece 92 having a circumferential dimension of 20 cm and the second filler piece 92 comprising an inclined second filler piece portion 922 and a horizontal second filler piece portion 921, which are formed as one piece, as shown in Fig. 14, wherein the inclined portion 922 of the second filler piece is arranged in a distal portion of the 102 innermost material exit slot cavity and the horizontal portion 921 of the second filler piece is arranged in the main portion 101 of the innermost material exit slot cavity, as shown in the Fig. 14, Fig. 10, Fig. 11 and Fig. 7 shown;
[0019] As in the Fig. 11 and Fig. 7, the number of the second filling piece 92 and the first filling piece 91 is one each, wherein the second filling piece 92 and the first filling piece 91 have the same orientation relative to the center axis of the film blowing machine head, and the second filling piece 92 and the first stuffing piece 91 have the same shape and structure.
[0020] As in the Fig. 7, Fig. 8, Fig. 9 and Fig. 10, between the annular inner sub-module and the annular outer sub-module, a first sleeve 1, a second sleeve 2, a third sleeve 3 and a fourth sleeve 4 are further provided in the order from the inside to the outside, wherein the upper end surfaces of the first sleeve 1 and second sleeve 2 have a larger upwards and smaller downwards reverse taper, while the upper end surfaces of the third sleeve 3 and fourth sleeve 4 have a smaller upwards and larger downwards positive taper; The inner sub-module 5, the first sleeve 1, the second sleeve 2, the third sleeve 3, the fourth sleeve 4, and the outer sub-module 6 are collectively referred to as sleeves. The vertical center axis position of each sleeve is the same, and an annular gap is formed between each inner and outer adjacent sleeve; and a plurality of spiral groove flow channels are formed on the surface of the annular gap between each inner and outer adjacent sleeve, the spiral groove flow channels being evenly distributed between every two adjacent sleeve layers along the circumferential direction of the sleeves; the annular gap and the spiral groove flow channel between every two adjacent sleeve layers form a material spreading flow channel for a layer of molten material.In particular, the annular gap 20 and the spiral groove flow channel 21 between the inner sub-module 5 and the first sleeve 1 form a material spreading flow channel for the second layer of molten material; the annular gap 30 and the spiral groove flow channel 31 between the first sleeve 1 and the second sleeve 2 form a material spreading flow channel for the third layer of molten material; the annular gap 40 and the spiral groove flow channel 41 between the second sleeve 2 and the third sleeve 3 form a material spreading flow channel for the fourth layer of molten material; the annular gap 50 and the spiral groove flow channel 51 between the third sleeve 3 and the fourth sleeve 4 form a material spreading flow channel for the fifth layer of molten material;the annular gap 60 and the spiral groove flow channel 61 between the fourth sleeve 4 and the fifth sleeve 5 form a material spreading flow channel for the sixth layer of molten material; the annular converging flow channel comprises an annular vertical converging flow channel, an annular positive conical converging flow channel 14 and an annular reverse-conical converging flow channel 13. Between the upper part of the outer upper module 8 and the upper part of the inner upper module 7 there is a radial gap, the radial gap forming the component of the annular vertical converging flow channel, and in particular it is the lower section 12 of the annular vertical converging flow channel (corresponding to the flow channel of section KH in Fig. 9); an outer connection module 90 is arranged above the outer upper module 8, and an inner connection module 9 is arranged above the inner upper module 7. Between the outer connection module 90 and the inner connection module 9 there is a radial gap, wherein the radial gap forms an upper section 17 of the annular vertical converging flow channel (corresponds to the flow channel of section KH in Fig. 9); the upper portion 17 of the annular vertical converging flow channel and the lower portion 12 of the annular vertical converging flow channel form an annular vertical converging flow channel, and the upper end of the annular vertical converging flow channel is connected to the annular extrusion outlet 15.
[0021] The annular inverted-conical converging flow channel 13 (corresponds to the flow channel of section HE in Fig. 9) is formed by the annular gap between the lower part of the inner upper module 7 and the upper end surface of the second sleeve 2; the annular positive conical converging flow channel 14 (corresponds to the flow channel of section HD in Fig. 9) is formed by the annular gap between the lower part of the outer upper module 8 and the upper end face of the third sleeve 3; the annular vertical converging flow channel, the annular positive conical converging flow channel 14 and the annular reverse-conical converging flow channel 13 form an inverted Y-shape in radial cross section, as shown in the Fig. 8, Fig. 9 and Fig. 10. In particular, the flow channel MH, the flow channel HD and the flow channel HE, as shown in Fig. 9, an inverted Y-shape; as in the Fig. 7, Fig. 8, Fig. 9 and Fig.10, the outer edge of the innermost material exit slot cavity 10 is directly connected to the lower end of the annular inverted-conical converging flow channel 13, wherein the upper end of the annular gap between the inner sub-module 5 and the first sleeve 1 is directly connected to the lower end of the annular inverted-conical converging flow channel 13, wherein the upper end of the annular gap between the first sleeve 1 and the second sleeve 2 is directly connected to the lower end of the annular inverted-conical converging flow channel 13, wherein the upper end of the annular gap between the second sleeve 2 and the third sleeve 3 is connected to the lower end of the annular vertical converging flow channel (iethe lower end of the lower section 12 of the annular vertical converging flow channel); wherein the upper end of the annular gap between the third sleeve 3 and the fourth sleeve 4 is directly connected to the lower end of the annular positive conical converging flow channel 14, wherein the upper end of the annular gap between the fourth sleeve 4 and the outer sub-module 6 is directly connected to the lower end of the annular positive conical converging flow channel 14, wherein the inner edge of the outermost material exit slot cavity 70 is directly connected to the lower end of the annular positive conical converging flow channel 14.
[0022] In the above embodiment, the circumferential dimension of the first filler 91 and the second filler 92 can be changed to 8 cm or 30 cm. Example II
[0023] A method for producing seven-layer coextrusion blown films using the seven-layer coextrusion blown film production line of the above-mentioned embodiment 1 comprises the following steps: (1) Each layer of molten plastic flows into the corresponding set of material spreading flow channels; Among them, the innermost molten resin is made of PA material, and the innermost molten resin flows from the starting point of each externally rotating horizontal vortex flow channel 11 along the externally rotating horizontal vortex flow channel 11. During this process, the innermost molten resin also discharges into the innermost material discharge slot cavity 10 adjacent to the externally rotating horizontal vortex flow channel 11, so that the innermost molten resin is spread (expanded) into a circular ring shape. However, when the innermost layer of molten resin approaches the outer edge of the innermost material discharge slot cavity 10, the innermost layer of molten resin is missing due to the occupation of the second filler 92 at the corresponding position; The second layer of molten plastic consists of PE (polyethylene) + TIE (adhesive resin). The second layer of molten plastic flows upward along the spiral groove flow channel 21 between the inner-bottom module 5 and the first sleeve 1 and continuously discharges upward from the annular gap 20 between the inner-bottom module 5 and the first sleeve 1, so that the second layer of molten plastic expands into a circular ring shape. The third layer of molten plastic is made of PE (polyethylene). The third layer of molten plastic flows upward along the spiral groove flow channel 31 between the first sleeve 1 and the second sleeve 2 and continuously discharges upward from the annular gap 30 between the first sleeve 1 and the second sleeve 2, so that the third layer of molten plastic expands into a circular ring shape. The fourth layer of molten plastic is made of PE (polyethylene). The fourth layer of molten plastic flows upwards along the spiral groove flow channel 41 between the second sleeve 2 and the third sleeve 3 and continuously from the annular gap 40 between the second sleeve 2 and the third sleeve 3 upwards, so that the fourth layer of molten plastic expands into a circular ring shape; The fifth layer of molten plastic is made of PE (polyethylene). The fifth layer of molten plastic flows upward along the spiral groove flow channel 51 between the third sleeve 3 and the fourth sleeve 4 and continuously discharges upward from the annular gap 50 between the third sleeve 3 and the fourth sleeve 4, so that the fifth layer of molten plastic expands into a circular ring shape. The sixth layer of molten plastic consists of PE (polyethylene) + TIE (adhesive resin). The sixth layer of molten plastic flows upward along the spiral groove flow channel 61 between the fourth sleeve 4 and the outer sub-module 6 and continuously discharges upward from the annular gap 60 between the fourth sleeve 4 and the outer sub-module 6, so that the sixth layer of molten plastic expands into a circular ring shape. The outermost molten plastic is made of PA material, and the outermost molten plastic flows from the starting point 710 of each internally rotating horizontal vortex flow channel 71 along the internally rotating horizontal vortex flow channel 71. During this process, the outermost molten plastic also flows into the outermost material discharge slot cavity 70 adjacent to the internally rotating horizontal vortex flow channel 71, so that the outermost molten plastic is spread (expanded) into a circular ring shape. However, as the outermost layer of molten plastic approaches the inner edge of the outermost material discharge slot cavity 70, the outermost layer of molten plastic is missing due to the occupation of the first filler 92 at the corresponding position; (2) The innermost layer of molten plastic, the second layer of molten plastic, and the third layer of molten plastic merge at the lower end of the annular inverted converging flow channel 13 and then flow upward along the annular inverted converging flow channel 13 to form a first converging flow; the outermost layer of molten plastic, the sixth layer of molten plastic, and the fifth layer of molten plastic merge at the lower end of the annular positive conical converging flow channel 14 and then flow upward along the annular positive conical converging flow channel 14 to form a second converging flow; the first converging flow,The fourth layer of molten plastic and the second converging flow further fuse at the lower end of the lower section 12 of the annular vertical converging flow channel. In this way, the seven layers of UA molten plastic fuse and flow into the lower section 12 of the annular vertical converging flow channel, then flow upward from the upper section 17 of the annular vertical converging flow channel, and are finally extruded together from the annular extrusion outlet 15 to form a film bubble. The resulting film bubble has a seven-layer plastic composite structure. From inside to outside, these are the innermost plastic layer, the second plastic layer, the third plastic layer, the fourth plastic layer, the fifth plastic layer, the sixth plastic layer, and the outermost plastic layer.wherein the innermost plastic layer and the outermost plastic layer are made of PA material, and the outermost plastic layer is missing at the position corresponding to the first filler piece 91. The innermost plastic layer is missing at the position corresponding to the second filler piece 92. The missing part of the outermost plastic layer and the missing part of the innermost plastic layer are located at the same position (i.e., overlap inside and outside); (3) The obtained cylindrical film bubble is cut longitudinally, and the cutting line is located in the middle of the missing part of the innermost plastic layer and the outermost plastic layer, so that the cylindrical film bubble becomes a sheet-shaped plastic film; the sheet-shaped plastic film is cut transversely to form a plurality of plastic films; overlap the edges of different plastic films and weld them together. For every two plastic films welded together, the welded part of the first plastic film is located at the missing part of the innermost plastic (ie, the part where the PA material is missing), and the welded part of the second plastic film is located at the missing part of the outermost plastic (ie, the part where the PA material is missing).In other words, the actual surface layers for welding are the second layer of the first plastic film and the sixth layer of the second plastic film. Therefore, it is easy to weld and can be welded (overlapped) in the transverse direction to form a wide greenhouse film suitable for advertising and use. The welding part of the first plastic film can be the right edge of the plastic film, and the welding part of the second plastic film can be the left edge of the plastic film; or the welding part of the first plastic film can be the left edge of the plastic film, and the welding part of the second plastic film can be the right edge of the plastic film.
Claims
[1] A multi-layer co-extruded blown film production line configured to co-extrude multiple layers of molten materials to form a plastic film bubble having a multi-layer composite structure, the multi-layer co-extruded blown film production line comprising a film blowing machine head, the film blowing machine head being equipped with an annular extrusion outlet, an annular converging flow channel, and a plurality of sets of material spreading channels, each set of material spreading channels directing the flow of a layer of molten material and spreading the layer of molten material into a ring shape, the downstream end of each set of material spreading channels being connected to the annular converging flow channel, and the annular converging flow channel being connected to the annular extrusion outlet; wherein the material spreading flow channel corresponding to the outermost layer of molten material comprises an annular outermost material exit gap cavity, the outermost material exit gap cavity being vertically joined by an annular outer upper module and an annular outer lower module, the outer upper module being located above the outer lower module, and a vertical gap being located between the inner parts of the outer upper module and the inner parts of the outer lower module, the vertical gap forming the outermost material exit gap cavity, the outer edge of the outermost material exit gap cavity being closed, and the inner edge of the outermost material exit gap cavity being connected to the annular converging flow channel; wherein a plurality of internally rotating horizontal vortex flow channels are formed on the surface of the outermost material exit slot cavity; characterized bythat the proximal section of the outermost material outlet slot cavity has a taper that is smaller towards the top and larger towards the bottom, wherein the part of the outermost material outlet slot cavity that is not the proximal section is referred to as the main section of the outermost material outlet slot cavity; wherein the outermost material outlet slot cavity is provided with a first filler piece, wherein the first filler piece comprises an inclined section of the first filler piece and a horizontal section of the first filler piece, which are designed as a single piece, wherein the inclined section of the first filler piece is arranged in a proximal section of the outermost material outlet slot cavity and the horizontal section of the first filler piece is arranged in the main section of the outermost material outlet slot cavity; that the material spreading flow channel corresponding to the innermost layer of molten material comprises an annular innermost material exit slot cavity, wherein the innermost material exit slot cavity is vertically joined by an annular inner upper module and an annular inner lower module, wherein the inner upper module is located above the inner lower module, wherein the outer lower module is located at the outer edge of the inner lower module, and the outer upper module is located at the outer edge of the inner upper module; wherein a vertical gap is located between the outer part of the inner upper module and the outer part of the inner lower module, wherein the vertical gap forms the innermost material exit slot cavity; wherein the outer edge of the innermost material exit slot cavity is closed, and the inner edge of the innermost material exit slot cavity is connected to the annular converging flow channel;wherein a plurality of internally rotating horizontal vortex flow channels are formed on the surface of the innermost material exit slot cavity; that the distal portion of the outermost material exit slot cavity has a larger taper towards the top and smaller taper towards the bottom, wherein the part of the outermost material exit slot cavity that is not the distal portion is referred to as the main portion of the innermost material exit slot cavity;wherein the outermost material exit slot cavity is provided with a second filler piece, wherein the second filler piece comprises an inclined portion of the second filler piece and a horizontal portion of the second filler piece, which are formed as a single piece, wherein the inclined portion of the second filler piece is arranged in a distal portion of the innermost material exit slot cavity and the horizontal portion of the second filler piece is arranged in the main portion of the innermost material exit slot cavity; wherein the second filler piece and the first filler piece have the same orientation relative to the central axis of the film blowing machine head. [2] Multilayer coextruded blown film production plant according to claim 1, characterized bythat the multi-layer co-extruded blown film production line is a seven-layer co-extruded blown film production line; wherein between the annular inner sub-module and the annular outer sub-module, a first sleeve, a second sleeve, a third sleeve and a fourth sleeve are further provided in sequence from the inside to the outside, wherein the inner sub-module, the first sleeve, the second, the third sleeve, the fourth sleeve and the outer sub-module are collectively referred to as sleeves, the vertical center axis position of each sleeve being the same, the upper end surfaces of the first and second sleeves having a reverse taper that is larger towards the top and smaller towards the bottom, while the upper end surfaces of the third and fourth sleeves have a positive taper that is smaller towards the top and larger towards the bottom;wherein an annular gap is formed between the inner and outer sleeves, and a plurality of spiral groove flow channels are formed on the surface of the annular gap between each inner and outer adjacent sleeve, wherein the annular gap and the spiral groove flow channel form a material spreading flow channel for the molten material between each two adjacent sleeve layers; that the annular converging flow channel comprises an annular vertical converging flow channel, an annular positive conical converging flow channel, and an annular inverted conical converging flow channel, wherein the annular vertical converging flow channel, the annular positive conical converging flow channel, and the annular inverted conical converging flow channel form an inverted Y-shape in radial cross-section; wherein the annular inverted converging flow channel is formed by the annular gap between the lower part of the inner upper module and the upper end surface of the second sleeve; wherein the annular positive conical converging flow channel is formed by the annular gap between the lower part of the outer upper module and the upper end surface of the third tube;wherein between the upper part of the outer upper module and the upper part of the inner upper module there is a radial gap which forms part of the annular vertical converging flow channel; that the outer edge of the innermost material outlet slot cavity is directly connected to the lower end of the annular inverted-conical converging flow channel, wherein the upper end of the annular gap between the inner sub-module and the first sleeve is directly connected to the lower end of the annular inverted-conical converging flow channel, wherein the upper end of the annular gap between the first sleeve and the second sleeve is directly connected to the lower end of the annular inverted-conical converging flow channel, wherein the upper end of the annular gap between the second sleeve and the third sleeve is connected to the lower end of the annular vertical converging flow channel, wherein the upper end of the annular gap between the third sleeve and the fourth sleeve is directly connected to the lower end of the annular positive conical converging flow channel,wherein the upper end of the annular gap between the fourth sleeve and the outer sub-module is directly connected to the lower end of the annular positive conical converging flow channel, wherein the inner edge of the outermost material exit slot cavity is directly connected to the lower end of the annular positive conical converging flow channel., [3] Multilayer coextruded blown film production plant according to claim 2, characterized bythat an outer connection module is further provided above the outer upper module, and an inner connection module is further provided above the inner upper module, wherein a radial gap is located between the outer connection module and the inner connection module, which forms an upper portion of an annular vertical converging flow channel, while the radial gap between the upper part of the outer upper module and the upper part of the inner upper module forms a lower portion of the annular vertical converging flow channel. [4] Multilayer coextruded blown film production plant according to claim 1, 2 or 3, characterized by that the first filler piece has a circumference dimension of 8 to 30 cm and the second filler piece has a circumference dimension of 8 to 30 cm.
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CN122626463A