Forming System and Method for Functional Polymer Materials in Film Blowing Processing

Abstract

A forming system and method for functional polymer materials in blown film processing. The forming method includes forming a parison from the melt of the functional polymer material through a blown film die head; the parison is blown and formed into a film bubble with the assistance of a forming unit; and the film bubble is cooled and solidified to form a functional polymer material film. According to the usage requirements, the present invention can precisely and controllably adjust the anisotropy of the target functional polymer film by adjusting the transverse blow-up ratio, the temperature in the blow-forming stage, the draw ratio, etc. in the temperature-controlled forming stage.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer film processing, and in particular to a forming system and method for blow-molding functional polymer materials. Background Art

[0002] Film products of functional polymer materials such as polyphenylene sulfide, polyimide, polyether amide, thermotropic liquid crystal polymer, high melt index polyolefin material, nylon, polyether ether ketone, and polytetrafluoroethylene have huge application markets and potentials in fields such as high-frequency communication, aerospace, and electronic appliances due to their respective excellent use properties; biodegradable film products prepared from biodegradable materials such as polylactic acid, polybutylene succinate, and polyhydroxyalkanoate have gradually become the mainstream of soft packaging materials; however, although the above-mentioned film products of various functional polymer materials have very excellent use properties in their respective fields, they usually face problems such as too low or too high melt viscosity, poor melt strength, melt fracture, poor thermal stability, and difficulty in film formation when preparing films. Processing these film products often requires the use of various complex processing techniques, with high forming costs, and large-scale production and preparation are restricted by many factors.

[0003] Blow-molding processing technology is an economical and efficient polymer film forming technology, and among them, multi-layer co-extrusion blow-molding means that multi-layer materials are simultaneously extruded from a co-extrusion die head to obtain a multi-layer co-extrusion composite film. During multi-layer co-extrusion blow-molding, different extruded layer materials usually endow different properties, and most of these materials are blow-molding grade resins with excellent blow-molding processing properties or their blends. Therefore, how to use the multi-layer co-extrusion blow-molding technology to prepare film products of the above-mentioned functional polymer materials with excellent use properties but poor blow-molding processing properties or even difficult to blow-mold is of great significance. However, to achieve this goal, two problems need to be solved: First, how to continuously and uniformly extrude the target functional polymer material from the annular die; Second, how to achieve the inflation of the tubular parison into a film and ensure the uniformity of the formed film. Summary of the Invention

[0004] In view of this, one of the main purposes of the present invention is to provide a forming system and method for blow-molding functional polymer materials, in order to at least partially solve at least one of the above technical problems.

[0005] To achieve the above object, as one aspect of the present invention, there is provided a forming method for blow-molding functional polymer materials, including:

[0006] Forming a parison from the melt of the functional polymer material through a blow-molding die head;

[0007] The parison is blown and formed into a film bubble with the assistance of a forming unit;

[0008] The vesicles are cooled and solidified to form a functional polymer material film.

[0009] As another aspect of the present invention, there is also provided a forming system for a functional polymer material, comprising:

[0010] A die head, which is arranged at the end of an extruder, and

[0011] A forming unit, the forming unit is connected to the die orifice of the die head, and the forming unit comprises a forming mandrel or a forming mold cavity.

[0012] Based on the above technical solutions, the forming system and method for blow molding a functional polymer material of the present invention has at least one or a part of the following advantages over the prior art:

[0013] 1. The present invention adopts the method of multi-layer co-extrusion blow molding, and the fully plasticized functional polymer material is uniformly and continuously extruded from the multi-layer co-extrusion die orifice under the wrapping of a protective layer material with excellent processing performance;

[0014] 2. The present invention can precisely and controllably adjust the anisotropy of the target functional polymer film by adjusting the transverse blow-up ratio, the temperature in the temperature-controlled forming stage, the draw ratio, etc. according to the usage requirements;

[0015] 3. The forming system and method for blow molding a functional polymer material provided by the present invention has the advantages of simple process technology and wide application range, and can realize the blow molding of various functional polymer materials with poor blow molding processing performance or even difficult to blow mold. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention, and for those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0017] Figure 1 It is a schematic structural diagram of a five-layer co-extrusion blow molding die head and a temperature-controlled forming device provided in Embodiment 1 of the present invention;

[0018] Figure 2 It is a schematic structural diagram of a forming mold cavity provided in Embodiment 1 of the present invention;

[0019] Figure 3 It is a schematic structural diagram of a temperature-controlled forming device provided in Embodiment 2 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the following provides a further detailed description of the present invention in conjunction with specific embodiments and with reference to the accompanying drawings.

[0021] The present invention provides a forming device and method for processing functional polymer materials by blown film to achieve the blown film processing of functional polymer materials with poor blown film processing performance or even difficult blown film processing; the present invention can precisely, continuously, and controllably adjust the anisotropy and mechanical balance of the functional polymer film; the film prepared by the present invention has good thickness uniformity and good surface flatness.

[0022] The present invention discloses a forming method for functional polymer materials, including:

[0023] Forming a parison from the melt of the functional polymer material through a blown film die head;

[0024] The parison is blown and formed into a film bubble with the assistance of a forming unit;

[0025] The film bubble is cooled and solidified to form a functional polymer material film.

[0026] In some embodiments of the present invention, in the blown forming step, for crystalline polymer materials, the temperature T p of the blown forming ranges from: T p ≥T c + 5°C, where T c is the crystallization temperature; for amorphous polymer materials, the temperature T p ≥T g + 10°C, where T g is the glass transition temperature;

[0027] In some embodiments of the present invention, in the cooling and solidifying step, for crystalline polymer materials, the temperature T s of the cooling and solidifying ranges from: T s ≤T c - 5°C, for amorphous polymer materials, the temperature T p ≤T g - 10°C.

[0028] In some embodiments of the present invention, the forming method further includes secondary blowing of the film bubble after the blown forming to form the film bubble and before cooling and solidifying;

[0029] In some embodiments of the present invention, in the secondary blowing step, for crystalline polymer materials, the temperature T e of the secondary blowing ranges from: T e ≥T c + 5°C, T cis the crystallization temperature; for amorphous polymer materials, the temperature T of the secondary blow-up e ≥T g + 15 °C, where T g is the glass transition temperature.

[0030] In some embodiments of the present invention, the forming method further includes heat setting the formed functional polymer material film after the cooling and curing step;

[0031] In some embodiments of the present invention, in the heat setting step, for crystalline polymer materials, the heat setting T h has a range of: T h ≥T c , where T c is the crystallization temperature; for amorphous polymer materials, the heat setting temperature T h ≥T g + 5 °C, where T g is the glass transition temperature.

[0032] In some embodiments of the present invention, the forming unit includes a forming mandrel or a forming die cavity.

[0033] In some embodiments of the present invention, the blown film die head is a co-extrusion die head;

[0034] The target functional polymer material is arranged in the flow channel near the middle in several flow channels of the co-extrusion die head, and the protective layer material is arranged in at least one flow channel of the remaining flow channels.

[0035] The present invention also discloses a forming system for blow-molding a functional polymer material, including:

[0036] A die head, which is arranged at the end of the extruder, and

[0037] A forming unit, the forming unit is connected to the die orifice of the die head, and the forming unit includes a forming mandrel or a forming die cavity.

[0038] In some embodiments of the present invention, the die head is a co-extrusion die head, and the co-extrusion die head includes several flow channels and a co-extrusion flow channel, and the ends of the several flow channels are all connected to the starting end of the co-extrusion flow channel;

[0039] In some embodiments of the present invention, a filtering structure is arranged in each of the flow channels.

[0040] In some embodiments of the present invention, the ratio of the diameter of the co-extrusion flow channel of the co-extrusion die head to the diameter of the die orifice of the co-extrusion die head is 0.2 to 50.

[0041] In some embodiments of the present invention, a smooth transition structure is arranged between the die orifice of the co-extrusion die head and the forming unit;

[0042] In some embodiments of the present invention, the forming system further includes a wind cooling circulation unit, and the outlet of the wind cooling circulation unit is arranged on the side wall of the forming system;

[0043] In some embodiments of the present invention, the wind cooling circulation unit includes a cooling air ring;

[0044] In some embodiments of the present invention, the forming system further includes a temperature control unit arranged on the side wall of the forming system, and the temperature control unit is used to adjust the temperature outside the film bubble;

[0045] In some embodiments of the present invention, the forming system further includes circulation air holes, and the circulation air holes are arranged on the side wall of the forming system.

[0046] In some embodiments of the present invention, the forming system further includes a heat insulation layer for preventing heat convection in the film blowing and forming stage and the cooling and solidifying stage.

[0047] In some embodiments of the present invention, the forming system further includes a heating sleeve for heating the coextrusion die head, and the coextrusion die head is arranged inside the heating sleeve.

[0048] In an exemplary embodiment, the forming system for blow molding functional polymer materials in the present invention includes: a coextrusion die head with three or more layers and a supporting temperature control forming device, and by using the method of coextrusion of three or more layers, the blow molding processing of various polymer materials with poor blow molding processing performance or even difficult to perform blow molding processing can be realized; the functional polymer materials with poor blow molding processing performance or even difficult to perform blow molding processing and the protective layer materials are uniformly plasticized by different extruders and then enter the coextrusion die head with three or more layers.

[0049] The temperature control forming device is directly connected to the outlet of the die head, and the multi-layer coextruded parison enters the temperature control forming device immediately after being extruded from the die head;

[0050] The coextrusion die head with three or more layers is provided with a filtering structure on the die head flow divider. Before the material enters the coextrusion flow channel, the unfully plasticized solid particles can be filtered out. The ratio of the length of the die head coextrusion flow channel to the diameter of the die head is 0.2 - 50, for example, 0.2, 0.5, 0.8, 1.0, 2.0, 5.0, 8.0, 10, 20, 30, 40, 50. As this ratio increases, the uniformity of the multi-layer coextruded parison gradually improves, but too high a ratio will increase the difficulty of die head processing and preparation;

[0051] The target functional polymer material layer is arranged in the middle layer of the multi-layer co-extrusion. During the blown film process, under the covering of the protective layer material, a multi-layer co-extruded parison is extruded from the annular die, and then enters the supporting temperature control forming device. The temperature control forming device includes a forming component and a temperature control component. The forming component has structures such as a forming mandrel or a forming die cavity. The film bubble can be formed by adhering to the surface of the forming mandrel or the inner wall of the forming die cavity. The temperature control component can simultaneously and precisely regulate the temperature, air flow, etc. around the film bubble at different positions from the die, and perform blowing, curing, stretching, shaping, etc. on the tubular parison at different positions from the die according to the intrinsic characteristics of the processing raw material.

[0052] In the present invention, the innermost or outermost layer of the multi-layer co-extrusion, that is, the extrusion layer in direct contact with the forming mandrel or the forming die cavity during the temperature control forming stage, has a relatively small adhesion force between the material of this layer and the forming mandrel or the forming die cavity, preventing the film bubble from sticking to the forming mandrel or the forming die cavity during the forming process.

[0053] In the temperature control forming device described above, the forming mandrel and the forming die cavity can be selected according to the processing characteristics of the target polymer material, and are applicable to the blown film processing of functional polymer materials with various poor blown film processing performances, such as too low or too high melt viscosity, poor melt strength, melt fracture, poor thermal stability, and difficulty in film formation, or even difficult blown film processing.

[0054] In the present invention, the temperature control forming device precisely regulates external field conditions such as the temperature and air flow around the film bubble by controlling the heating power of the heating unit arranged therein through the temperature control system and controlling the flow rate and air volume of the circulating air flow by the air flow generating unit, and realizes steps such as lateral blowing, cooling and shaping, secondary blowing, and heat setting of the multi-layer tubular parison containing the functional polymer material layer.

[0055] In the present invention, there is no strict requirement for the form of the temperature control system and the heating unit. Various known heating forms can be adopted, including but not limited to electric heating, infrared heating, high-frequency electromagnetic heating, electron beam heating, etc. From the perspective of practicality, electric heating is preferably adopted. The heating elements include but not limited to heating blocks, heating plates, heating wires, heating tubes, etc. Here, the main shape of the film bubble is cylindrical. From the perspective of heating uniformity, the appearance shape of the temperature control forming device is set as a cylindrical shape with a diameter larger than the film bubble. The lower end of the temperature control forming device is connected to the die outlet plane, and is sequentially divided into a lateral blowing stage and a cooling and shaping stage according to functions. A secondary blowing stage and a heat setting stage can also be set according to requirements. Among them, the temperature difference between the lateral blowing stage and the cooling stage is relatively large, and an adiabatic layer is arranged in the transition region between the two. The adiabatic layer in the present invention is filled with adiabatic materials in the lateral blowing stage and the cooling and shaping stage. The adiabatic materials include but not limited to mica plates, foamed glass plates, etc.

[0056] The present invention has no strict requirements on the form of the airflow generating unit, and various known airflow generating methods can be used, including but not limited to centrifugal fans, axial flow fans, rotary fans, etc. From a practical point of view, it is preferred to use a centrifugal fan with stepless speed regulation.

[0057] Transverse blowing stage: The temperature-controlled molding device maintains the temperature around the film bubble according to the characteristics of the processed raw materials, so that the functional polymer material still has good molding and blowing capabilities, and realizes transverse blowing film formation with the assistance of the coating of the protective layer material and the molding core rod or the molding mold cavity. The core rod and the mold cavity are directly connected to the die and have a smooth transition structure with the die outlet. The changing shape is designed according to the intrinsic characteristics of the raw materials, and the maximum size is determined by the maximum transverse blowing ratio that needs to be achieved.

[0058] During the transverse inflation stage, the temperature of the atmosphere around the film bubble is heated to T by the temperature control system. p For crystalline polymer materials, the temperature T p The range is: T p ≥T c +5℃, T c is the crystallization temperature; for amorphous polymer materials, the temperature of this stage is T p ≥T g +10℃, T g is the glass transition temperature; at this time, the polymer preform extruded from the die head is still in a stretchable deformable state, and the preform is sleeved on the outer surface of the forming core rod. Due to the traction of the traction roller, the preform moves longitudinally along the forming core rod, and the lateral size of the preform gradually increases with the increase of the diameter of the forming core rod, so as to achieve lateral expansion. The preform can also be attached to the inner surface of the forming mold cavity. The compressed gas blown in from the air inlet of the mold core blows the preform to the inner wall of the forming mold cavity, and gradually increases with the increase of the diameter of the cavity, so as to achieve lateral expansion. The initial outer diameter of the forming core rod and the initial inner diameter of the forming mold cavity are the same as the inner diameter of the preform. The outer diameter of the forming core rod and the inner diameter of the forming mold should be smoothly transitioned and gradually increased. Here, the co-extrusion die head also includes an airflow generating unit. The airflow generated by the airflow generating unit forms an airflow layer between the film bubble and the forming unit to reduce the adhesion between the film bubble and the forming unit. Compared with the conventional film blowing processing method, the used forming core rod and the forming mold cavity assist the lateral expansion of the polymer material with poor film blowing processing performance or even difficult film blowing processing;

[0059] Cooling and shaping stage: The film bubble after lateral expansion in the lateral expansion stage is pulled by the traction roller to the cooling and shaping stage for cooling. The applied cooling airflow gradually cools and solidifies the formed film bubble to prevent wrinkling and warping during the solidification process. Generally, for crystalline polymer materials, the temperature T in this stage is s The range is: T s≤T c -5 °C. For amorphous polymer materials, the temperature T in this stage p ≤T g -10 °C; In the cooling and shaping stage, a cooling air ring is provided. The cooling air ring is connected to an air flow generating unit. The air flow generating unit blows cooling air into the cooling air ring. The cooling air blows from the air outlet of the air ring towards the formed film bubble. The hot air is discharged from the circulating air outlet of the temperature control forming device to cool the film bubble. A temperature control system is connected between the air flow generating unit and the cooling air ring, which can control the temperature of the blown cooling air. Finally, by jointly controlling the temperature and flow rate of the air flow, the purpose of regulating the cooling rate of the film bubble is achieved, realizing controllable cooling; In the cooling and shaping stage, the temperature control forming device applies cooling air with different temperatures and flow rates to the film bubble, realizing the gradual cooling and solidification of the film bubble, and reducing the wrinkling phenomenon of the film during the solidification process.

[0060] In some embodiments of the present invention, temperature control forming stages such as secondary blowing and heat setting of the film can also be provided; The film is continuously heated to the forming processing temperature in the secondary blowing stage, and with the assistance of the forming mandrel, the forming die cavity and the blowing air flow, the second transverse blowing and stretching of the film are realized; In the heat setting stage of the film, the atmosphere around the film bubble is heated to the specified heat setting temperature to eliminate the internal stress in the film and increase the dimensional stability of the film. Specifically:

[0061] Secondary blowing stage: If the blowing ratio of the film bubble of some materials in the transverse forming stage is not sufficient to meet the requirements or the achievable blowing ratio is limited, then secondary blowing is required. The structure of the forming unit required in the secondary blowing stage is similar to that in the transverse blowing stage, and is arranged at the rear end of the traction roller. The initial outer diameter of the forming mandrel and the initial inner diameter of the forming die cavity are equal to the diameter of the film bubble obtained in the cooling and shaping stage. The temperature control element heats the temperature of the atmosphere around the film bubble to near the stretchable deformation temperature of the film bubble again. For crystalline polymer materials, the temperature T in this stage e The range is: T e ≥T c +5 °C. For amorphous polymer materials, the temperature T in this stage e ≥T g +15 °C; The film bubble is sleeved on the outer surface of the forming mandrel. Due to the traction of the second traction roller arranged above in the secondary blowing stage, the film bubble moves longitudinally along the forming mandrel, and the transverse size of the film bubble also gradually increases as the diameter of the forming mandrel increases, realizing secondary blowing. The film bubble can also adhere to the inner surface of the forming die cavity, and compressed gas is blown into the film bubble to blow the film bubble to the inner wall of the forming die cavity and gradually increases as the inner diameter of the cavity increases, realizing secondary blowing;

[0062] Heat setting stage: Some materials need to be heat set after blown film forming to eliminate internal stress in the film, improve the degree of crystallization perfection, etc. Then heat setting is required. Heat setting is set between the cooling and setting stage and the haul-off roll or between the secondary inflation stage and the second haul-off roll. In the heat setting stage, the molecular chains of the polymer material should be in a state where they can move, and the film should not produce macroscopic deformation. The selection of the ambient temperature around the film bubble in this stage is more critical. For crystalline polymer materials, the temperature T h has a range of: T h ≥T c . For amorphous polymer materials, the temperature T h ≥T g +5°C. For specific films, further adjustment is required according to actual needs. A temperature control system is set in this stage to maintain the temperature of the ambient atmosphere around the film bubble at T h .

[0063] The shaped film bubble is finally hauled by the haul-off roll and wound up to obtain a multilayer coextruded composite film. For the obtained multilayer coextruded composite film, processes such as peeling and laminating can be carried out on the composite film according to the film characteristics and usage requirements to obtain the target functional polymer film. The present invention uses the method of multilayer coextrusion and the described temperature-controlled forming device to solve the problems such as poor melt strength, melt fracture, uneven extrusion, and difficult film forming in the forming process of functional polymer films.

[0064] In the present invention, when preparing a single-layer target functional polymer film, the material of the coextruded layer directly connected to the middle functional polymer layer and the target functional polymer material must have a low adhesion force, and the difference in melting points of different materials is less than 250°C to facilitate the peeling process after film forming.

[0065] The functional polymer material is a polymer material with poor blown film processing performance, and even difficult to carry out blown film processing; including but not limited to liquid crystal polymer materials, polyethylene terephthalate, polyphenylene sulfide, polyimide, polyether amide, high melt index polyolefin materials, nylon, etc. with low melt viscosity and poor melt strength; polyether ether ketone, polytetrafluoroethylene, etc. with high melt viscosity and difficult thermoforming; polylactic acid, polybutylene succinate, polyhydroxy fatty acid ester, etc. with a narrow processing window and poor thermal stability; the functional polymer material can be a pure resin of the foregoing, or a blend containing one or more of the foregoing resins.

[0066] The described protective layer materials include various materials that can be processed by blown film, such as polyethylene, polypropylene, polybutene, ethylene / acrylic acid copolymer, ethylene / methacrylic acid copolymer, ethylene / vinyl acetate copolymer, ethylene / vinyl alcohol copolymer, polyvinyl chloride, polystyrene, poly(4-methylpentene), polyethylene terephthalate, nylon, aromatic liquid crystal polyester, polybutylene adipate / terephthalate, fluororesin, etc.; the protective layer materials can be a single one of the aforementioned blown film resins or a blend containing one or more of the aforementioned blown film resins.

[0067] The prepared functional polymer film has good thickness uniformity, and the anisotropy of the film can be precisely and controllably adjusted according to different usage requirements.

[0068] The protective layer in the multi-layer co-extruded composite film can be peeled off as a protective film for the functional polymer film after molding or before use, or can be used as an adhesive layer to assist in the lamination, compounding, etc. of the functional polymer film.

[0069] The technical solutions of the present invention will be further described below through specific embodiments in conjunction with the accompanying drawings. It should be noted that the following specific embodiments are only for illustration purposes, and the protection scope of the present invention is not limited thereto.

[0070] The chemical reagents and raw materials used in the following embodiments are all commercially available or prepared by known preparation methods.

[0071] Example 1

[0072] As Figure 1-2As shown in the figure, an embodiment of the present invention provides a forming device for processing functional polymer materials by blown film, including a five-layer co-extrusion die head 1 and a temperature control forming device 13; the target functional polymer material and the protective layer material are respectively added into the extruder, and after being melted and plasticized by the extruder, they enter the co-extrusion die head 1. The target functional polymer material enters the flow channel 4, and the protective layer materials enter the flow channels 2, 3, 5, and 6 respectively. After the materials enter the flow channels 2, 3, 4, 5, and 6, they first pass through a filtering structure in their respective flow channels to filter out the unfully melted solid particles, and finally converge into the co-extrusion flow channel 9. The ratio of the length of the co-extrusion flow channel to the die diameter is 0.2 - 50. Adjusting this ratio can regulate the thickness distribution of the functional polymer material in the die co-extrusion stage and ensure the circumferential uniformity of the materials. The heating sleeve 8 ensures that the processed materials after filtering are always in a molten state; the target functional polymer material forms co-extruded materials under the wrapping of the protective layer and is evenly extruded from the annular die 11, and then enters the temperature control forming device 13. The blowing air flow enters the inside of the annular parison from the die core air inlet 10. Adjust the temperature control module 16 at the lower part of the side wall of the temperature control forming device 15 in the film blowing and forming stage so that the parison 12 is still in a plastic stage. The internal blowing air flow blows the parison / blown film 12 to the inner wall of the forming mold cavity 14. Under the support of the forming mold cavity 14, the blown film 12 is gradually blown up along with the change of the shape and size of the inner wall of the forming mold cavity 14. The material of the forming mold cavity can be polytetrafluoroethylene material, and the structure is as Figure 2 shown. In order to further weaken the adhesion between the blown film 12 and the forming mold cavity 14, auxiliary air flow can also be input between the two, and an air flow component is set. The air flow generated by the air flow component is used to form an air flow layer to realize the auxiliary blowing of the forming mold cavity 14 to the blown film 12 while weakening the influence on its longitudinal traction; the blown film 12 after transverse blowing is pulled to the film cooling and solidification stage. Since there is a large temperature difference between the film blowing and forming stage and the cooling and solidification stage, an insulating layer 17 is provided at the middle position of the side wall of the temperature control forming device to prevent heat convection; in addition to gradually reducing the ambient temperature to Ts in the film cooling and solidification stage, a blowing and cooling circulation unit is provided. The cooling air ring 18 blows the cooling air flow to the blown film 12, and the hot air flow is discharged from the circulating air holes 19 until the target functional polymer film is solidified and formed.

[0073] Experimental Example 2

[0074] Using the forming device and method for functional polymer materials in blow film processing provided in the above specific embodiment 1, a biodegradable polymer poly(3-hydroxybutyrate-co-4-hydroxybutyrate) film is prepared. The melting point of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) is 150 °C, the crystallization temperature is 126 °C, the protective layer materials are polyethylene and modified polybutylene adipate / terephthalate, and their melting points are 112 °C and 125 °C respectively. Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) has a low melt viscosity, a narrow processing temperature window, and poor thermal stability, and cannot be directly processed by blow film. As Figure 1 shown, the poly(3-hydroxybutyrate-co-4-hydroxybutyrate) material enters the flow channel 4, polyethylene enters the flow channels 3 and 5, and the modified polybutylene adipate / terephthalate enters the flow channels 2 and 6. The die temperature is 160 °C, the temperature in the film blowing and forming stage is 131 - 135 °C, the blow-up ratio is 2.5, and the modified polybutylene adipate / terephthalate has good opening properties and does not adhere to the Figure 2 shown forming die cavity; the temperature in the film cooling and solidifying stage is 115 - 121 °C, and the total thickness of the finally obtained five-layer co-extruded film is 180 μm. The bonding force between polyethylene and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) is low, and the protective layer material can be directly peeled off to obtain a single-layer poly(3-hydroxybutyrate-co-4-hydroxybutyrate) film with a thickness of about 30 μm; the outer layer of polybutylene adipate / terephthalate film can also be peeled off from the polyethylene layer to obtain a polybutylene adipate / terephthalate film.

[0075] Experimental Example 3

[0076] Using the same method as in Example 2, the difference from Example 2 is that the temperature in the film blowing and forming stage is 140 - 145 °C, the blow-up ratio is 3.5, the temperature in the film cooling and solidifying stage is 80 - 85 °C, the total thickness of the finally obtained five-layer co-extruded film is 140 μm, and the protective layer material is directly peeled off to obtain a single-layer poly(3-hydroxybutyrate-co-4-hydroxybutyrate) film with a thickness of about 24 μm.

[0077] Example 4

[0078] Using the same method as in Example 1, the difference from Example 1 is that: as Figure 3 shown, the forming die cavity 14 in Example 1 is changed to a forming mandrel 20. The transverse blowing and stretching of the film bubble mainly depends on the increase in the transverse dimensions at different positions of the forming mandrel 20 from the die 11. For materials that are prone to phenomena such as melt fracture during the blowing process, by designing the forming mandrel 20 with different size-changing shapes, the uniform transverse blowing and stretching of the film bubble is achieved.

[0079] Experimental Example 5

[0080] Using the forming device and method for blow-molding functional polymer materials provided in the above specific Embodiment 4, a polyphenylene sulfide film was prepared. The melting point of polyphenylene sulfide is 285°C, and the protective layer material is a blow-molding grade polypropylene resin containing 2% antiblocking agent, with a melting point of 150°C. The processing temperature of polyphenylene sulfide is high and the melt viscosity is unstable. Its film products usually need to be obtained by using complex lamination techniques. As Figure 1 shown, the polyphenylene sulfide material enters the flow channel 4, and polyethylene enters the flow channels 2, 3, 5, and 6. The die temperature is 300°C, the temperature in the film blowing and forming stage is 295 - 305°C, and the blow-up ratio is 2.0; the temperature in the film cooling and solidifying stage is 50 - 80°C. Finally, the total thickness of the five-layer co-extruded film obtained is 200 μm. The bonding force between polypropylene and polyphenylene sulfide is low, and the protective layer material can be directly peeled off to obtain a single-layer polyphenylene sulfide film with a thickness of about 40 μm.

[0081] In summary, the forming device and method for blow-molding functional polymer materials provided by the present invention can achieve the blow-molding processing of various functional polymer materials with poor blow-molding processing performance or even difficult blow-molding processing. At the same time, the anisotropy of the film can be controllably adjusted according to different usage requirements; the film forming device and method have a simple processing process and a wide application range.

[0082] The parts not elaborated in detail in the present invention belong to the well-known technologies in the art.

[0083] It should be noted that although the present invention has been shown and described with reference to specific exemplary embodiments of the present invention, those skilled in the art should understand that the present invention is not limited to the above embodiments. Any modifications or variations to the present invention that do not depart from the spirit and scope of the present invention, provided that these modifications and variations fall within the scope of the claims of the present invention and the equivalent technical scope, then the present invention also means including these modifications and variations.

[0084] In particular, without departing from the spirit and teachings of the present invention, the features recited in the various embodiments and / or claims of the present invention can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly recited in the present invention. All such combinations and / or combinations are within the protection scope of the present invention. Therefore, the scope of the present invention is not only determined by the appended claims, but also should be defined by the equivalents of the appended claims.

Claims

1. A forming method for a functional polymer material, comprising: Forming a parison from the melt of the functional polymer material through a blown film die; The parison is blown and formed into a film bubble with the assistance of a forming unit; The film bubble is cooled and solidified to form a functional polymer material film; Wherein, the functional polymer material includes one or more of liquid crystal polymer materials, polyethylene terephthalate, polyphenylene sulfide, polyimide, polyether amide, high melt index polyolefin materials, and nylon with low melt viscosity and poor melt strength; The blown film die is a co-extrusion die; The co-extrusion die includes a plurality of flow channels and a co-extrusion flow channel, and the ends of the plurality of flow channels are all connected to the starting end of the co-extrusion flow channel; The ratio of the length of the co-extrusion flow channel of the co-extrusion die to the diameter of the die orifice of the co-extrusion die is 0.2 to 50; Target functional polymer material is arranged in the flow channel near the middle in a plurality of flow channels of the co-extrusion die, and protective layer material is arranged in at least one flow channel of the remaining flow channels; In the blow molding step, for crystalline polymer materials, the temperature T of blow molding p is in the range of: T p ≥ T c + 5°C, where T c is the crystallization temperature; for amorphous polymer materials, the temperature T of blow molding p ≥ T g + 10°C, where T g is the glass transition temperature; In the cooling and solidifying step, for the crystalline polymer material, the temperature T of cooling and solidifying s is in the range of: T s ≤T c ≤ -5°C; for the amorphous polymer material, the temperature T of cooling and solidifying s ≤T g ≤ -10°C.

2. The forming method according to claim 1, characterized in that, The forming method further includes secondary blowing of the film bubble after the blown forming to form the film bubble and before cooling and solidification; In the secondary blow molding step, for crystalline polymer materials, the temperature T of the secondary blow molding e is in the range of: T e ≥ T c + 5°C, where T c is the crystallization temperature; for amorphous polymer materials, the temperature T of the secondary blow molding e ≥ T g + 15°C, where T g is the glass transition temperature.

3. The forming method according to claim 1, characterized in that, The forming method further includes heat setting the formed functional polymer material film after the cooling and solidification step; In the heat setting step, for crystalline polymer materials, the heat setting temperature T h is in the range of: T h ≥ T c , where T c is the crystallization temperature; for amorphous polymer materials, the heat setting temperature T h ≥ T g + 5°C, where T g is the glass transition temperature.

4. The forming method according to claim 1, characterized in that, The forming unit includes a forming mandrel or a forming die cavity.

5. A forming system for blow molding a functional polymer material applicable to the forming method according to any one of claims 1-4, comprising: A die, which is arranged at the end of an extruder; And A forming unit, the forming unit is connected to the die orifice of the die, and the forming unit includes a forming mandrel or a forming die cavity.

6. The forming system according to claim 5, characterized in that, The die is a co-extrusion die, and the co-extrusion die includes a plurality of flow channels and a co-extrusion flow channel, and the ends of the plurality of flow channels are all connected to the starting end of the co-extrusion flow channel; A filtering structure is arranged in each of the flow channels.

7. The forming system according to claim 5, characterized in that, The ratio of the length of the co-extrusion flow channel of the co-extrusion die to the diameter of the die orifice of the co-extrusion die is 0.2 to 50.

8. The forming system according to claim 5, characterized in that, A smooth transition structure is arranged between the die orifice of the co-extrusion die and the forming unit; The forming system further includes a wind cooling circulation unit, and the outlet of the wind cooling circulation unit is arranged on the side wall of the forming system; The wind cooling circulation unit includes a cooling air ring; The forming system further includes a temperature control unit arranged on the side wall of the forming system, and the temperature control unit is used to adjust the temperature outside the film bubble; The forming system further includes circulating air holes, and the circulating air holes are arranged on the side wall of the forming system.

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