1. A film blow molding device is characterized by comprising a blow molding unit (1), a traction adjusting unit (2) and an annealing unit (3);

the blow molding unit (1) comprises a heat preservation box body (11), wherein an annular die head (111), a heat preservation blow molding air ring (112) and a sizing heat preservation cylinder (113) are coaxially arranged in the heat preservation box body (11) from bottom to top in sequence;

the annular die head (111) is communicated with an extrusion outlet pipeline of the extruder (4);

the heat-preservation blow molding air ring (112) is communicated with the fan (5) through a heating pipeline (114);

the traction adjusting unit (2) is arranged on the blow molding unit (1), and the traction adjusting unit (2) pulls the film bubble obtained by blow molding to the annealing unit (3) through an annular opening formed in the upper part of the heat preservation box body (11).

2. The film blow molding device according to claim 1, wherein the sizing heat-preservation cylinder (113) is provided with an upper opening and a lower opening on the heat-preservation blowing air ring (112), and the ratio of the height to the inner diameter of the sizing heat-preservation cylinder (113) is 2-5: 1;

preferably, the sizing heat-preserving cylinder (113) can be vertically adjusted up and down and is used for controlling the distance between the sizing heat-preserving cylinder and the heat-preserving blow molding air ring (112);

preferably, the bottom of the sizing heat-preserving cylinder (113) is provided with a trumpet-shaped opening;

preferably, the inner wall of the sizing heat-preserving cylinder (113) is coated with a Teflon coating.

3. The film blow molding apparatus according to claim 1, wherein the traction adjustment unit (2) includes a width controller (21), a chevron plate (22), and a traction roller set (23);

preferably, the width controller (21), the herringbone plate (22) and the traction roller group (23) are arranged coaxially with the sizing heat-preserving cylinder (113).

4. The film blow molding device according to claim 3, wherein the herringbone plate (22) is a stainless steel plate coated with a Teflon layer coating on the surface, and the thickness of the Teflon layer coating is preferably 0.5-1.5 mm;

preferably, the included angle of the herringbone plate (22) is 60-120 degrees.

5. The film blow molding apparatus according to claim 3, wherein the width controller (21) is mainly composed of a guide wheel set and an infrared distance measuring sensor;

preferably, the set of drawing rolls (23) consists essentially of 1 heatable mirror roll and 1 rubber roll.

6. The film blow molding apparatus according to claim 1, wherein the annealing unit (3) consists essentially of 4 to 6 heatable mirror rollers.

7. A liquid crystal polymer film, which is produced mainly by the film blow molding apparatus according to any one of claims 1 to 6.

8. A method for preparing a liquid crystal polymer film according to claim 7, comprising the steps of:

extruding the molten liquid crystal polymer resin through an annular die head (111), and blowing the extruded tubular blank film under the heating gas blown out by a heat-preservation blow molding air ring (112) to form a film bubble; then, the film bubble sequentially passes through the sizing heat-preserving cylinder (113) and an upper annular opening of the heat-preserving box body (11) to the traction adjusting unit (2); and then the film bubble obtained by blow molding is drawn to an annealing unit (3) by a drawing adjusting unit (2) to obtain the formed liquid crystal polymer film.

9. The method for preparing a liquid crystal polymer film according to claim 8, wherein the temperature of the resin extruded from the annular die head (111) is 280-325 ℃.

10. The method for producing a liquid crystal polymer film according to claim 8, wherein the inflation ratio is 4.4, and the stretching ratio is 3.2;

preferably, the blown heated gas comprises one of hot air, hot nitrogen or hot argon.

Background

The 5G communication is an important basic network for bearing emerging industries such as ultra-high-speed mobile communication, Internet of things, artificial intelligence, intelligent transportation, remote medical treatment and the like in the future, and is highly valued and continuously invested in major countries in the world. The biggest characteristics of 5G communication over 4G communication are high frequency, high speed, large bandwidth and low latency, where the frequency will gradually transition to over 24GHz and the overall communication speed will be 100 times that of 4G.

Thermotropic Liquid Crystal Polymer (TLCP) thin films are considered to be the most ideal insulating material for the rf antenna flexible board of 5G terminal electronics because of their lower dielectric loss (less than 0.003), dimensional stability and low water absorption (less than 0.1%) compared to polyimide materials. Thermotropic liquid crystal polymer presents a rigid rod-like molecular structure, so that molecular chains of the thermotropic liquid crystal polymer are difficult to form chain entanglement in a molten state and are easy to be subjected to shearing force to generate orientation, and the melt viscosity of the thermotropic liquid crystal polymer is more sensitive to the change of shearing frequency and temperature compared with the traditional polymer. The characteristics of the liquid crystal polymer are easy to cause anisotropy of physical properties due to high molecular chain orientation in the film forming process. Currently, the main methods for producing thermotropic liquid crystalline polymer films include extrusion blow molding and extrusion-casting-biaxial stretching. Among them, the extrusion blow molding method has received the most widespread attention and application due to relatively low equipment investment and process difficulty.

However, because the liquid crystal polymer has the characteristics of extremely fast cooling and solidifying speed, strong molecular orientation, high rigidity and the like in the extrusion molding process, the traditional film blowing machine which is lack of targeted process control has the problems of easy film breaking, uneven thickness, serious MD/TD anisotropy of the film, poor smoothness and serious folding caused by severe torsional pendulum of the bubble film and the like when the traditional film blowing machine blows the liquid crystal polymer film.

Therefore, it is necessary and urgent to develop a film blowing apparatus for preparing a liquid crystal polymer film to alleviate the problems of easy film rupture during blowing, uneven thickness, severe MD/TD anisotropy of the film, etc. during blowing of the liquid crystal polymer film due to the characteristics of the liquid crystal polymer film such as very fast cooling and solidification speed, strong molecular orientation, and high rigidity during extrusion molding.

In view of the above, the present invention is particularly proposed.

Disclosure of Invention

The first purpose of the invention is to provide a film blow molding device, which can perform the film blow molding process under the heat preservation condition, effectively reduce the cooling speed of the liquid crystal polymer blank film, and alleviate the problems of easy film breaking, uneven thickness, serious MD/TD anisotropy of the film and the like in the blowing process of the liquid crystal polymer film in the existing preparation method.

The second objective of the present invention is to provide a liquid crystal polymer film, which has advantages of reliable performance and good appearance compared to the existing liquid crystal polymer film prepared by blow molding.

The third objective of the present invention is to provide a method for preparing a liquid crystal polymer film, wherein the method has characteristics of simple process, high finished product yield, and suitability for large-scale industrial production, and the prepared liquid crystal polymer film has characteristics of excellent continuous film forming property, flat and smooth appearance, uniform thickness, and excellent mechanical property.

The invention provides a film blow molding device which comprises a blow molding unit, a traction adjusting unit and an annealing unit, wherein the blowing unit is used for blowing a film to be molded;

the blow molding unit comprises a heat insulation box body, and an annular die head, a heat insulation blow molding air ring and a sizing heat insulation cylinder are coaxially arranged in the heat insulation box body from bottom to top in sequence;

the annular die head is communicated with an extrusion port pipeline of the extruder;

the heat-preservation blow molding air ring is communicated with the fan through a heating pipeline;

the traction adjusting unit is arranged on the blow molding unit and pulls the film bubble obtained by blow molding to the annealing unit through an annular opening arranged at the upper part of the heat preservation box body.

Further, the upper and lower openings of the sizing heat-preserving cylinder are arranged on a heat-preserving blow molding air ring, and the ratio of the height to the inner diameter of the sizing heat-preserving cylinder is 2-5: 1;

preferably, the sizing heat-preserving cylinder can be vertically adjusted up and down and is used for controlling the distance between the sizing heat-preserving cylinder and the heat-preserving blow molding air ring;

preferably, a trumpet-shaped opening is formed in the bottom of the sizing heat-preserving cylinder;

preferably, the inner wall of the sizing heat-preserving cylinder is coated with a Teflon coating.

Further, the traction adjusting unit comprises a width controller, a herringbone plate and a traction roller set;

preferably, the width controller, the herringbone plate and the traction roller set are arranged coaxially with the sizing heat-preserving cylinder.

Furthermore, the herringbone plate is a stainless steel plate coated with a Teflon layer coating on the surface, and the thickness of the Teflon layer coating is preferably 0.5-1.5 mm;

preferably, the included angle of the herringbone plate is 60-120 degrees.

Furthermore, the width controller mainly comprises a guide wheel set and an infrared distance measuring sensor.

Preferably, the traction roller group mainly comprises 1 heatable mirror surface roller and 1 rubber roller.

Furthermore, the annealing unit mainly comprises 4-6 heatable mirror rollers.

The liquid crystal polymer film provided by the invention is mainly prepared by the film blow molding device.

The invention provides a preparation method of the liquid crystal polymer film, which comprises the following steps:

extruding the molten liquid crystal polymer resin through an annular die head, and blowing the extruded tubular blank film under the heating gas blown out by a heat-preservation blow molding air ring to form a film bubble; then the film bubble sequentially passes through the sizing heat-insulation cylinder and an upper annular opening of the heat-insulation box body to the traction adjusting unit; and then drawing the film bubble obtained by blow molding to an annealing unit by a drawing adjusting unit to obtain the formed liquid crystal polymer film.

Further, the temperature of the resin extruded by the annular die head is 280-325 DEG^℃。

Further, the blow-up ratio is 4.4, and the draw ratio is 3.2;

preferably, the blown heated gas comprises one of hot air, hot nitrogen or hot argon.

Compared with the prior art, the invention has the beneficial effects that:

the invention provides a film blow molding device, which comprises a blow molding unit, a traction adjusting unit and an annealing unit; the blow molding unit comprises a heat insulation box body, and an annular die head, a heat insulation blow molding air ring and a sizing heat insulation cylinder are coaxially arranged in the heat insulation box body from bottom to top in sequence; wherein the annular die head is communicated with an extrusion outlet pipeline of the extruder and is used for extruding the resin in the extruder; the heat-preservation blow molding air ring is communicated with a fan through a heating pipeline, and the extruded tubular blank film is blown by heating gas under the heat-preservation condition; the sizing heat-preserving cylinder can further preserve heat of the blown bubble film to gradually cool the blown bubble film, and can play a role in preventing the bubble from twisting and stabilizing the diameter of the bubble; meanwhile, a traction adjusting unit is arranged on the blow molding unit and pulls the film bubble obtained by blow molding to the annealing unit through an annular opening formed in the upper part of the heat preservation box body. Therefore, the film blow molding device can be used for performing the film blow molding process under the heat preservation condition, effectively reducing the cooling speed of the liquid crystal polymer blank film, and relieving the problems that the film is easy to break, the thickness is uneven, the MD/TD anisotropy of the film is serious and the like in the blowing process when the liquid crystal polymer film is blown due to the characteristics of extremely high cooling and solidification speed, strong molecular orientation, high rigidity and the like of the liquid crystal polymer in the extrusion molding process in the conventional preparation method.

The liquid crystal polymer film provided by the invention is mainly prepared by the film blow molding device. Compared with the existing liquid crystal polymer film prepared by blow molding, the liquid crystal polymer film has the advantages of reliable performance and good appearance.

The preparation method of the liquid crystal polymer film provided by the invention comprises the following steps of firstly extruding liquid crystal polymer resin in a molten state through an annular die head, and blowing the extruded tubular blank film under heating gas blown out by a thermal blow molding air ring to form a film bubble; then the film bubble sequentially passes through the sizing heat-insulation cylinder and an upper annular opening of the heat-insulation box body to the traction adjusting unit; and then drawing the film bubble obtained by blow molding to an annealing unit by a drawing adjusting unit to obtain the formed liquid crystal polymer film. The preparation method has the advantages of simple process, high finished product yield and suitability for large-scale industrial production, and simultaneously, the prepared liquid crystal polymer film has excellent continuous film forming property, flat and smooth appearance, uniform thickness and excellent mechanical property.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a schematic view of an overall structure of a film blow molding apparatus according to embodiment 1 of the present invention;

fig. 2 is a schematic structural diagram of a blowing unit of the film blow molding apparatus according to embodiment 1 of the present invention;

fig. 3 is a schematic structural diagram of a drawing adjustment unit and an annealing unit of the film blow molding apparatus provided in embodiment 1 of the present invention.

Icon: 1-a blow molding unit; 2-a traction adjustment unit; 3-an annealing unit; 11-a heat preservation box body; 111-an annular die; 112-insulating blow molding air ring; 113-sizing a heat preservation cylinder; 4-an extruder; 114-heating the pipe; 5, a fan; 21-width controller; 22-herringbone plates; 23-set of traction rollers.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

According to one aspect of the present invention, a film blow molding apparatus includes a blowing unit 1, a draft adjusting unit 2, and an annealing unit 3;

the blow molding unit 1 comprises a heat preservation box body 11, wherein an annular die head 111, a heat preservation blow molding air ring 112 and a sizing heat preservation cylinder 113 are coaxially arranged in the heat preservation box body 11 from bottom to top in sequence;

the annular die head 111 is communicated with an extrusion outlet pipeline of the extruder 4;

the heat-preservation blow molding air ring 112 is communicated with the fan 5 through a heating pipeline 114;

the traction adjusting unit 2 is arranged on the blow molding unit 1, and the traction adjusting unit 2 draws the film bubble obtained by blow molding to the annealing unit 3 through an annular opening formed in the upper portion of the heat preservation box body 11.

The invention provides a film blow molding device, which comprises a blow molding unit 1, a traction adjusting unit 2 and an annealing unit 3; the blow molding unit 1 comprises a heat preservation box body 11, wherein an annular die head 111, a heat preservation blow molding air ring 112 and a sizing heat preservation cylinder 113 are coaxially arranged in the heat preservation box body 11 from bottom to top in sequence; wherein the annular die head 111 is in pipe communication with an extrusion port of the extruder 4 for extruding the resin from the extruder 4; the heat-preservation blow molding air ring 112 is communicated with a fan 5 through a heating pipeline 114, and the extruded tubular blank film is subjected to blow molding by using heating gas under the heat-preservation condition; the sizing heat-preserving cylinder 113 can further preserve heat of the blown bubble film to gradually cool the blown bubble film, and can play a role in preventing the bubble from twisting and stabilizing the diameter of the bubble; meanwhile, a traction adjusting unit 2 is arranged on the blow molding unit 1, and the traction adjusting unit 2 draws the film bubble obtained by blow molding to the annealing unit 3 through an annular opening formed in the upper part of the heat preservation box body 11. Therefore, the film blow molding device can ensure that the film blow molding process is carried out under the heat preservation condition, effectively reduces the cooling speed of the blank film of the liquid crystal polymer, and relieves the problems of extremely high cooling and solidifying speed, strong molecular orientation, high rigidity and the like of the liquid crystal polymer in the extrusion molding process, easy film breaking, uneven thickness, serious MD/TD anisotropy of the film and the like in the blowing process of the liquid crystal polymer film.

In a preferred embodiment of the present invention, the thermal insulation box 11 is composed of a tempered glass and an aluminum alloy frame which can withstand a long-term high temperature of 250 ℃ or higher, has a structure in which both the front and back surfaces can be opened and closed, has a visual window, and can be conveniently opened and closed. Meanwhile, the upper part of the heat preservation box body 11 is provided with an annular opening to enable the bubble film to leave the heat preservation room.

As a preferred embodiment, the heat-insulating box body 11 can isolate the annular die head 111, the heat-insulating blow air ring 112 and the sizing heat-insulating cylinder 113 from the external environment, prevent the influence of environmental dust, temperature and air flow on the film blowing process, keep the balance and stability of the internal environment, and make the film blowing process more stable and controllable.

In a preferred embodiment of the present invention, the heat-insulating blow-molding air ring 112 may blow 25-250 ℃ hot air, the hot air is heated by the heating pipeline 114, and the air duct design and the air outlet duct arrangement of the heat-insulating blow-molding air ring 112 should ensure that the hot air is uniformly blown out on the circumference. The arrangement of the heat-preservation blow molding air ring 112 can effectively slow down the cooling and solidification speed of the liquid crystal polymer tubular blank film extruded by the annular die head, and increase the time of the tubular blank film in a stretching state, thereby being beneficial to the transverse uniform blowing of the blank film and solving the problems of molecular chain orientation and uneven thickness.

In a preferred embodiment, the heating ducts 114 are provided with air volume adjusting switches, and are uniformly distributed around the heat-preserving blowing air ring 112 (at 90 degrees intervals). The design of the air duct and the arrangement of the air outlet duct of the heat-preservation blow-molding air ring 112 are not particularly limited, as long as the hot air can be effectively ensured to be uniformly blown out on the heat-preservation blow-molding air ring 112. The hot air temperature control range of the air ring is 25-250 ℃, and the air speed control range is 0-5 m/s.

In a preferred embodiment of the present invention, the sizing heat-insulating cylinder 113 is a cylinder having an upper and lower opening, and is provided on the heat-insulating blow ring 112, and a ratio of a height to an inner diameter of the sizing heat-insulating cylinder 113 is 2 to 5: 1; the specific dimensional specification and height/inner diameter ratio can be adjusted according to actual production needs and material classes.

In the above preferred embodiment, the sizing heat-preserving cylinder 113 is vertically adjustable for controlling the distance from the heat-preserving blow molding air ring 112;

in the above preferred embodiment, the bottom of the sizing heat-preserving cylinder 113 is provided with a trumpet-shaped opening, so that part of the hot air from the air ring can enter the cylinder, thereby playing a heat-preserving effect on the bubble film and reducing the cooling speed.

In the above preferred embodiment, the inner wall of the sizing heat-insulating cylinder 113 is coated with a teflon coating, or the inner wall of the sizing heat-insulating cylinder 113 is mirror-finished, so as to reduce the influence of the friction force when the bubble contacts the inner wall of the heat-insulating cylinder on the film surface.

Preferably, the sizing heat-preserving cylinder 113 can be vertically lifted and lowered by a slide rail, so as to adjust the distance between the sizing heat-preserving cylinder 113 and the heat-preserving blow molding air ring 112.

In a preferred embodiment of the invention, the traction adjustment unit 2 comprises a width controller 21, a chevron plate 22 and a traction roller set 23;

preferably, the width controller 21, the herringbone plate 22 and the traction roller group 23 are arranged coaxially with the sizing heat-preserving cylinder 113.

In the above preferred embodiment, the herringbone plate 22 is a stainless steel plate coated with a teflon layer coating on the surface, and the thickness of the teflon layer coating is preferably 0.5-1.5 mm;

preferably, the included angle of the herringbone plate 22 is 60-120 degrees.

In a preferred embodiment, the chevron plate 22 can effectively prevent the bubble film from locally deforming due to excessive friction force when the bubble slides in contact with the chevron plate 22 during convergence, thereby preventing film surface defects.

In the above preferred embodiment, the width controller 21 is mainly composed of a guide wheel set and an infrared distance measuring sensor.

As a preferred embodiment, the width controller 21 is composed of three sets of guide wheels (four guide wheels each having a diameter of 10mm) and an infrared distance measuring sensor, and is used for further preventing the bubble membrane from twisting and measuring the inner diameter of the bubble membrane; meanwhile, the extruder 4 and the metering pump are fed back to adjust the extrusion amount according to the change of the inner diameter.

In the preferred embodiment described above, the set of pulling rolls 23 consists essentially of 1 heatable mirror-surface roll and 1 rubber roll.

In a preferred embodiment, the traction roller set 23 is composed of a combination of a heatable mirror roller and a rubber roller, the temperature control range of the mirror roller is 25-200 ℃, the surface of the rubber roller is coated with silica gel, and the diameters and the lengths of the mirror roller and the rubber roller can be designed and adjusted according to actual production requirements. The temperature-controllable drawing roller group 23 can effectively prevent the film bubble from wrinkling caused by too fast cooling when the film bubble is folded.

Preferably, the herringbone plate 22 and the traction roller are fixed on a lifting upright post, and the lifting range is 0-800 mm.

In a preferred embodiment of the invention, the annealing unit 3 consists essentially of 4 to 6 heatable mirror rollers.

As a preferred embodiment, the annealing unit 3 is composed of 4 heatable mirror surface rollers, the temperature control range is 25-200 ℃, the rollers are arranged in a zigzag manner, the surface temperature of the rollers is distributed in a gradient cooling mode, the film is annealed to eliminate internal stress, the film is gradually cooled, and the problems of warping of the film appearance and the like are solved.

According to one aspect of the present invention, a liquid crystal polymer film is mainly produced by the above film blow molding apparatus.

The liquid crystal polymer film provided by the invention is mainly prepared by the film blow molding device. Compared with the existing liquid crystal polymer film prepared by blow molding, the liquid crystal polymer film has the advantages of reliable performance and good appearance.

The film blow molding apparatus of the present invention may be used for blow molding of other film products. For example, when the non-liquid crystal polymer film is blown, the heat retaining and annealing unit 3 of the film blow molding apparatus of the present invention may be closed.

According to an aspect of the present invention, a method for preparing the liquid crystal polymer film comprises the following steps:

extruding the melted liquid crystal polymer resin through an annular die head 111, and blowing the extruded tubular blank film under the heating gas blown out by a heat-preservation blowing air ring 112 to form a film bubble; then the film bubble sequentially passes through the sizing heat-preserving cylinder 113 and the upper annular opening of the heat-preserving box body 11 to the traction adjusting unit 2; and then the drawing adjusting unit 2 draws the film bubble obtained by blow molding to an annealing unit 3 to obtain the formed liquid crystal polymer film.

The preparation method of the liquid crystal polymer film provided by the invention comprises the following steps of firstly extruding liquid crystal polymer resin in a molten state through an annular die head 111, and blowing the extruded tubular blank film under heating gas blown by a heat-preservation blow molding air ring 112 to form a film bubble; then the film bubble sequentially passes through the sizing heat-preserving cylinder 113 and the upper annular opening of the heat-preserving box body 11 to the traction adjusting unit 2; and then the drawing adjusting unit 2 draws the film bubble obtained by blow molding to an annealing unit 3 to obtain the formed liquid crystal polymer film. The preparation method has the advantages of simple process, high finished product yield and suitability for large-scale industrial production, and simultaneously, the prepared liquid crystal polymer film has excellent continuous film forming property, flat and smooth appearance, uniform thickness and excellent mechanical property.

In a preferred embodiment of the present invention, the temperature of the resin extruded from the annular die 111 is 280 to 325 ℃.

In a preferred embodiment of the present invention, the blow-up ratio is 4.4, the draw ratio is 3.2;

in a preferred embodiment, the blow-up ratio is in the range of 3 to 5, and the draw ratio is preferably in the range of 3 to 4.

Preferably, the blown heated gas comprises one of hot air, hot nitrogen or hot argon.

The technical solution of the present invention will be further described with reference to the following examples.

Example 1

As shown in fig. 1 and 2, a film blow molding apparatus includes a blowing unit 1, a draft adjusting unit 2, and an annealing unit 3;

the blow molding unit 1 comprises a heat preservation box body 11, wherein an annular die head 111, a heat preservation blow molding air ring 112 and a sizing heat preservation cylinder 113 are coaxially arranged in the heat preservation box body 11 from bottom to top in sequence;

the annular die head 111 is communicated with an extrusion outlet pipeline of the extruder 4;

the heat-preservation blow molding air ring 112 is communicated with the fan 5 through a heating pipeline 114;

the traction adjusting unit 2 is arranged on the blow molding unit 1, and the traction adjusting unit 2 draws the film bubble obtained by blow molding to the annealing unit 3 through an annular opening formed in the upper portion of the heat preservation box body 11.

The film blow molding device comprises a blow molding unit 1, a traction adjusting unit 2 and an annealing unit 3; the blow molding unit 1 comprises a heat preservation box body 11, wherein an annular die head 111, a heat preservation blow molding air ring 112 and a sizing heat preservation cylinder 113 are coaxially arranged in the heat preservation box body 11 from bottom to top in sequence; wherein the annular die head 111 is in pipe communication with an extrusion port of the extruder 4 for extruding the resin from the extruder 4; the heat-preservation blow molding air ring 112 is communicated with a fan 5 through a heating pipeline 114, and the extruded tubular blank film is subjected to blow molding by using heating gas under the heat-preservation condition; the sizing heat-preserving cylinder 113 can further preserve heat of the blown bubble film to gradually cool the blown bubble film, and can play a role in preventing the bubble from twisting and stabilizing the diameter of the bubble; meanwhile, a traction adjusting unit 2 is arranged on the blow molding unit 1, and the traction adjusting unit 2 draws the film bubble obtained by blow molding to the annealing unit 3 through an annular opening formed in the upper part of the heat preservation box body 11. Therefore, the film blow molding device can ensure that the film blow molding process is carried out under the heat preservation condition, effectively reduces the cooling speed of the blank film of the liquid crystal polymer, and relieves the problems of extremely high cooling and solidifying speed, strong molecular orientation, high rigidity and the like of the liquid crystal polymer in the extrusion molding process, easy film breaking, uneven thickness, serious MD/TD anisotropy of the film and the like in the blowing process of the liquid crystal polymer film.

In this embodiment, the heat-insulating box body 11 is composed of tempered glass and an aluminum alloy frame, which can withstand a long-term high temperature of more than 250 ℃, has a structure in which both the front surface and the back surface can be opened and closed, has a visual window, and can be conveniently opened and closed. Meanwhile, the upper part of the heat preservation box body 11 is provided with an annular opening to enable the bubble film to leave the heat preservation room.

As a preferred embodiment, the heat-insulating box body 11 can isolate the annular die head 111, the heat-insulating blow air ring 112 and the sizing heat-insulating cylinder 113 from the external environment, prevent the influence of environmental dust, temperature and air flow on the film blowing process, keep the balance and stability of the internal environment, and make the film blowing process more stable and controllable.

In this embodiment, the heat-insulating blow-molding air ring 112 may blow 25-250 ℃ hot air, the hot air is heated by the heating pipeline 114, and the air duct design and the air outlet duct arrangement of the heat-insulating blow-molding air ring 112 should ensure that the hot air is uniformly blown out on the circumference. The arrangement of the heat-preservation blow molding air ring 112 can effectively slow down the cooling and solidification speed of the liquid crystal polymer tubular blank film extruded by the annular die head, and increase the time of the tubular blank film in a stretching state, thereby being beneficial to the transverse uniform blowing of the blank film and solving the problems of molecular chain orientation and uneven thickness.

Preferably, the heating pipes 114 are provided with air volume adjusting switches, and are uniformly distributed around the heat-preserving blowing air ring 112 (at 90 degrees intervals). The design of the air duct and the arrangement of the air outlet duct of the heat-preservation blow-molding air ring 112 are not particularly limited, as long as the hot air can be effectively ensured to be uniformly blown out on the heat-preservation blow-molding air ring 112. The hot air temperature control range of the air ring is 25-250 ℃, and the air speed control range is 0-5 m/s.

Referring to fig. 2, the sizing heat-preserving cylinder 113 is in a cylindrical shape with an upper opening and a lower opening, and is arranged on the heat-preserving blowing air ring 112, and the ratio of the height to the inner diameter of the sizing heat-preserving cylinder 113 is 2-5: 1; the specific dimensional specification and height/inner diameter ratio can be adjusted according to actual production needs and material classes.

Preferably, the sizing heat-preserving cylinder 113 can be vertically adjusted up and down, and is used for controlling the distance between the sizing heat-preserving cylinder and the heat-preserving blow molding air ring 112;

referring to fig. 2, a trumpet-shaped opening is formed in the bottom of the sizing heat-preserving cylinder 113, so that part of hot air coming out of the air ring can enter the cylinder, the heat-preserving effect on the bubble film is achieved, and the cooling speed of the bubble film is reduced.

In a preferred embodiment, the inner wall of the sizing heat-preserving cylinder 113 is coated with a teflon coating, or the inner wall of the sizing heat-preserving cylinder 113 is mirror-finished, so as to reduce the influence of the friction force when the bubble contacts the inner wall of the heat-preserving cylinder on the film surface.

Preferably, the sizing heat-preserving cylinder 113 can be vertically lifted and lowered by a slide rail, so as to adjust the distance between the sizing heat-preserving cylinder 113 and the heat-preserving blow molding air ring 112.

Referring to fig. 3, the traction adjustment unit 2 in this embodiment includes a width controller 21, a chevron plate 22, and a traction roller group 23; the width controller 21, the herringbone plate 22 and the traction roller group 23 are arranged coaxially with the sizing heat-preserving cylinder 113.

In the above preferred embodiment, the herringbone plate 22 is a stainless steel plate coated with a teflon layer coating on the surface, and the thickness of the teflon layer coating is preferably 0.5-1.5 mm; the included angle of the herringbone plate 22 is 60-120 degrees.

In a preferred embodiment, the chevron plate 22 can effectively prevent the bubble film from locally deforming due to excessive friction force when the bubble slides in contact with the chevron plate 22 during convergence, thereby preventing film surface defects.

Referring to fig. 3, the width controller 21 is mainly composed of a guide wheel set and an infrared distance measuring sensor.

Preferably, the width controller 21 comprises three sets of guide wheels (each set having a diameter of 10mm) and an infrared distance measuring sensor, and plays roles in further preventing the bubble membrane from twisting and measuring the inner diameter of the bubble membrane; meanwhile, the extruder 4 and the metering pump are fed back to adjust the extrusion amount according to the change of the inner diameter.

In this embodiment, the traction roller set 23 mainly includes 1 heatable mirror roller and 1 rubber roller. In a preferred embodiment, the traction roller set 23 is composed of a combination of a heatable mirror roller and a rubber roller, the temperature control range of the mirror roller is 25-200 ℃, the surface of the rubber roller is coated with silica gel, and the diameters and the lengths of the mirror roller and the rubber roller can be designed and adjusted according to actual production requirements. The temperature-controllable drawing roller group 23 can effectively prevent the film bubble from wrinkling caused by too fast cooling when the film bubble is folded.

Preferably, the herringbone plate 22 and the traction roller are fixed on a lifting upright post, and the lifting range is 0-800 mm.

In this embodiment, the annealing unit 3 is mainly composed of 4 to 6 heatable mirror rollers. The temperature control range of the annealing unit 3 is 25-200 ℃, the annealing unit is arranged in a Z shape, the temperature of the roller surface is distributed in a gradient cooling mode, the film is annealed to eliminate internal stress, the film is gradually cooled, and the problems of warping of the film appearance and the like are solved.

Example 2

A liquid crystal polymer film produced by the film blow molding apparatus of example 1;

the preparation method of the liquid crystal polymer film comprises the following steps:

(1) and carrying out vacuum drying treatment on the liquid crystal polymer resin in a vacuum oven at the treatment temperature of 140 ℃ and 160 ℃ for 4-12 h. The liquid crystal polymer resin is mainly synthesized by 73 percent of p-hydroxybenzoic acid and 27 percent of 6-hydroxy-2-naphthoic acid through a solid phase polycondensation method, and a small amount of a third monomer can be introduced on the basis of the two monomers, wherein the melting point of the resin is 280-283 ℃.

And then, melting the dried liquid crystal polymer resin raw material at the temperature of 280-295 ℃ charging barrel by a single-screw extruder 4 to uniformly plasticize the liquid crystal polymer resin raw material, wherein the diameter of the screw is 35mm, the length-diameter ratio of the screw is 32, removing infusible substances and impurities by a filter screen, and stably supplying the melt by a metering pump, wherein the extrusion capacity is 13 kg/h.

(2) Further compressing and homogenizing the liquid crystal polymer resin melt extruded by the extruder 4 in the step (1) through an annular die head 111, and extruding a tubular blank film, wherein the diameter of the annular die head 111 is 45mm, the gap is 0.8mm, and the temperature of the die head is controlled at 282 ℃.

(3) The extruded tubular blank film is blown up by blowing-up gas at the temperature of 180 ℃ at the heat preservation temperature (the wind speed is 0.5m/s) of hot air at the temperature of 210 ℃ blown out from a heat preservation blow molding air ring 112 (the blowing-up ratio is 4.4, and the stretching ratio is 3.2) to form stable film bubbles, and the stable film bubbles enter a sizing heat preservation cylinder 113 and are gradually cooled, solidified and shaped (the vertical distance between the sizing heat preservation cylinder 113 and the air ring is 150mm, the inner diameter is 210mm, and the height is 420mm), so that the cylindrical sizing heat preservation cylinder 113 can prevent the twisting of the bubble film in the upward drafting process, and the diameter of the film bubbles can be controlled and stabilized; and then enters the width controller 21 through the annular opening at the upper part of the heat preservation box body 11 to carry out real-time detection and feedback adjustment on the size of the bubble.

(4) And (3) after the blown liquid crystal polymer film bubble is converged by the herringbone plate 22 with the included angle of 80-surface fluorine coating, the liquid crystal polymer film bubble enters a traction roller (the temperature of a mirror roller is controlled to be 150 ℃, the diameters of the two rollers are both 350mm, and the lengths of the two rollers are both 350mm), and then the liquid crystal polymer film bubble is gradually cooled to be below the glass transition temperature through 4 annealing roller sets with the temperatures set according to 130, 110, 90 and 70 ℃ gradients, is subjected to edge cutting and rolling to obtain the liquid crystal polymer film with the width of 320mm and the thickness of 50 um.

Example 3

A method for blow molding a liquid crystal polymer film, which is different from embodiment 2 in that:

the extrusion amount in the step (1) is 20 kg/h;

and (4) cutting edges and rolling to obtain the liquid crystal polymer film with the width of 320mm and the thickness of 75 um.

Example 4

A method for blow molding a liquid crystal polymer film, which is different from embodiment 2 in that:

the extrusion amount in the step (1) is 28 kg/h;

the die gap of the annular die head 111 in the step (2) is 1.0 mm;

and (4) cutting edges and rolling to obtain the liquid crystal polymer film with the width of 320mm and the thickness of 100 um.

Example 5

A method for blow molding a liquid crystal polymer film, which is different from embodiment 2 in that:

the liquid crystal polymer resin used in the step (1) is synthesized by 80 percent of p-hydroxybenzoic acid and 20 percent of 6-hydroxy-2-naphthoic acid through a solid phase polycondensation method, and the melting point of the resin is 320 ℃; the melting and plasticizing temperature of the single-screw extruder 4 is 320-335 ℃;

the temperature of the die head in the step (2) is 321 ℃;

the temperature of hot air blown out by the hot air ring in the step (3) is 240 ℃, and the temperature of inflation gas is 210 ℃;

and (4) cutting edges and rolling to obtain the liquid crystal polymer film with the width of 320mm and the thickness of 50 um.

Comparative example 1

A method for blow molding a liquid crystal polymer film, which is different from embodiment 2 in that:

in the step (3), the function of the heat-preservation blow molding air ring 112 is not started or the temperature is less than 160 ℃;

comparative example 2

A method for blow molding a liquid crystal polymer film, which is different from embodiment 2 in that:

the sizing heat-preserving cylinder 113 is not arranged in the step (3);

comparative example 3

A method for blow molding a liquid crystal polymer film, which is different from embodiment 2 in that:

the temperatures of the traction mirror surface roller and the annealing roller set in the step (4) are both normal temperature;

experimental example 1

The liquid crystal polymer film prepared by the method has the advantages of balanced mechanical properties, good thickness uniformity and capability of obviously eliminating defects such as uneven appearance or folds of the film. Now, the liquid crystal polymer films prepared in examples 2 to 5 and comparative examples 1 to 3 are subjected to performance detection, and the specific detection method is as follows:

(1) the tensile property was tested according to ASTM D882, the apparatus being an electronic universal tensile tester, at a tensile rate of 20 mm/min.

(2) Judging standard of appearance wrinkle defect: observing a 500 meter film sample, no less than 3 wrinkles observed is considered superior, 3-10 wrinkles observed is considered good, 11-50 wrinkles observed is considered medium, and more than 50 wrinkles observed is considered poor.

(3) The test criteria for film thickness uniformity are as follows: taking a 4m sample in the MD direction of the liquid crystal polymer film, measuring the thickness at intervals of 20cm, and counting the variance value of 20 points to evaluate the thickness uniformity of the film in the MD direction; a600 mm sample was taken in the TD direction of the liquid crystal polymer film, and then thickness measurement was conducted at intervals of 50mm, and the thickness uniformity of the film in the TD direction was evaluated by counting the standard deviation of 12 points.

The specific test results are shown in the following table:

the detection results show that the liquid crystal polymer film prepared by the film blow molding device provided by the invention has balanced MD (longitudinal direction)/TD (transverse direction) mechanical properties and good thickness uniformity, and can obviously eliminate the defects of uneven film appearance, wrinkles and the like.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.