Single-layer blown film extrusion die for producing lcp film

Abstract

This invention provides a single-layer blown film extrusion die for producing LCP films, comprising a die core, a die core outer sleeve, a die, and a die adjusting ring. The die core has a feed inlet at its bottom, and a cylindrical flow channel extends upward from the central region of its top surface. The outer surface of the cylindrical flow channel has at least two spiral grooves. The die core contains a main flow channel and at least two branch flow channels. The bottom of the main flow channel is connected to the feed inlet, and the bottom of the branch flow channels is connected to the top of the main flow channel. Each branch flow channel is connected to a spiral groove. The die core outer sleeve is attached to the top surface of the die core. The outer surface of the bottom of the cylindrical flow channel is tightly fitted to the die core outer sleeve, and the upper outer surface of the cylindrical flow channel forms an annular flow channel with the die core outer sleeve. The die is attached to the top surface of the cylindrical flow channel, and the die adjusting ring is attached to the top surface of the die core outer sleeve. An annular extrusion channel is formed between the die and the die adjusting ring. This invention can extrude cylindrical films with good extrusion quality.

Description

Technical Field

[0001] This invention relates to an extrusion die, and more particularly to a single-layer blown film extrusion die for producing LCP films. Background Technology

[0002] Due to the high frequency and high speed characteristics of 5G, the requirements for materials have become even more stringent, especially in reducing signal loss during transmission. LCP is currently the engineering plastic material with the lowest dielectric loss and the strongest overall advantages. Its use in base stations and mobile phones will increase significantly in the future. In the 5G mobile phone field, LCP, with its low and stable transmission loss, flexibility, dimensional stability, and low water absorption, is the material that best meets antenna requirements. Currently, PI (polyimide) substrate FPC (flexible printed circuit board) antenna modules are still the mainstream design solution for mobile phones. However, with the advent of the 5G era, it is expected that MPI and LCP substrate FPCs will be rapidly replaced. For example, Apple first introduced the LCP flexible board antenna solution in the iPhone 8, and in 2018, the three models XR / XS / XS Max continued to use the LCP antenna solution, using 3 / 3 / 2 LCP antennas respectively. This is Apple's early preparation for the 5G era. At the same time, LCP films can also be used in headphone diaphragms, high-barrier packaging films, automotive radar, and the Internet of Things (IoT) fields.

[0003] The main production methods for LCP membranes include solution casting, biaxial stretching, melt casting, and blown film.

[0004] The LCP raw material used in the solution casting method is not the thermotropic LCP commonly found on the market, but a lyotropic LCP polymerized from special monomers.

[0005] LCP materials exhibit significant differences in transverse and longitudinal strength, and are extremely prone to tearing in the transverse direction, necessitating substantial improvements to the stretching process and equipment. Biaxial stretching of LCP must be performed in a molten state, requiring the use of a supporting PTFE membrane to ensure the strength of the LCP after melting. This process demands the highest level of equipment quality, involves complex processing techniques, requires significant investment, and is accompanied by the high price of PTFE material.

[0006] LCP films produced by melt casting have a distinct longitudinal orientation and are extremely easy to tear laterally, but they should be called LCP sheets. LCP films manufactured by this method have high rigidity and are theoretically not suitable for flexible copper clad laminates, but are more suitable for rigid copper clad laminates. Summary of the Invention

[0007] To address the aforementioned problems, this invention aims to provide a single-layer blown film extrusion die for producing LCP films, which can effectively break the anisotropy of LCP molecular chains, enabling simultaneous stretching of LCP molecular chains in both longitudinal and transverse directions, resulting in good longitudinal and transverse matching and high-quality film extrusion.

[0008] The technical solution of this invention is a single-layer blown film extrusion die for producing LCP films, characterized in that it includes a die core, a die core outer sleeve, a die, and a die adjusting ring. The die core has a feed inlet at its bottom, and a cylindrical flow channel extends upward from the central region of its top surface. The outer surface of the cylindrical flow channel has at least two spiral grooves running upwards, with the lower and upper ends of the spiral grooves evenly distributed at equal angles along the circumference. The die core contains a main flow channel and at least two branch flow channels. The bottom of the main flow channel is connected to the feed inlet, and the bottom of each branch flow channel is connected to the top of the main flow channel. Each part is connected to the lower end of one of the spiral groove flow channels. The outer sleeve of the die core is connected to the top surface of the die core outside the cylindrical flow channel. The outer side of the bottom of the cylindrical flow channel is in close contact with the outer sleeve of the die core. The outer side of the upper part of the cylindrical flow channel and the outer sleeve of the die core have a gap to form an annular flow channel. The die is connected to the top surface of the cylindrical flow channel. The die adjusting ring is connected to the top surface of the die core outer sleeve. An annular extrusion channel is formed between the die and the die adjusting ring. The molten raw material enters through the feed port, passes through the main channel and the branch channel, and reaches the spiral groove flow channel. It then enters the annular extrusion channel through the annular flow channel and is extruded evenly.

[0009] Preferably, the depth of the spiral groove gradually decreases from bottom to top, and the gap of the annular flow channel gradually increases from bottom to top.

[0010] Preferably, the gap at the top of the annular flow channel corresponds to the gap size at the bottom of the annular extrusion channel.

[0011] Preferably, the annular extrusion channel includes a bottom inlet section, a middle variable diameter section, and a top shaping extrusion section. The inlet section corresponds to the annular flow channel. The gap between the lower and middle regions of the variable diameter section gradually increases, and the gap between the middle and upper regions of the variable diameter section gradually decreases. The lower region of the variable diameter section is in a tapering state from bottom to top. The shaping extrusion section is arranged axially.

[0012] Preferably, the die is connected to the top surface of the cylindrical flow channel via a screw.

[0013] Preferably, the outer sleeve of the mold core is connected to the top surface of the mold core by screws, and the die adjusting ring is connected to the top surface of the outer sleeve of the mold core by screws.

[0014] Preferably, the feed inlet is located in the central area of ​​the bottom surface of the mold core, the main flow channel is vertically arranged above the feed inlet, and the branch flow channel is inclined upward from the top of the main flow channel outward.

[0015] Preferably, the number of spiral groove channels and branch channels is 2, 4, 6 or other even numbers.

[0016] This invention can effectively break the anisotropy of LCP molecular chains, enabling simultaneous stretching of LCP molecular chains in both longitudinal and transverse directions, resulting in good longitudinal and transverse matching and high film extrusion quality. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a structural schematic diagram from another perspective of the present invention; Figure 3 To illustrate the cross-sectional view of the internal flow channel of this invention; Figure 4 This is an exploded view of the present invention; Figure 5 for Figure 4 A structural diagram from another perspective; Figure 6 This is a schematic diagram of the mold core in this invention (dashed lines show the feed inlet, main channel, and branch channels). Wherein: 1—Die core; 11—Feed inlet; 12—Cylindrical flow channel; 121—Spiral groove flow channel; 13—Main flow channel; 14—Branch flow channel; 2—Die core outer sleeve; 3—Die; 4—Die adjusting ring; 5—Annular flow channel; 6—Annular extrusion channel; 61—Inlet section; 62—Variable diameter section; 63—Shaping extrusion section. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to the accompanying drawings.

[0019] like Figures 1 to 6As shown, this invention provides a single-layer blown film extrusion die for producing LCP films, including a die core 1, a die core outer sleeve 2, a die 3, and a die adjusting ring 4. The die core 1 has a feed inlet 11 at its bottom. A cylindrical flow channel portion 12 extends upward from the central region of the top surface of the die core 1. At least two spiral groove flow channels 121 running from bottom to top are provided on the outer surface of the cylindrical flow channel portion 12. The lower and upper ends of the spiral groove flow channels 121 are evenly distributed at equal angles along the circumferential direction. The die core 1 contains a main flow channel 13 and at least two branch flow channels 14. The bottom of the main flow channel 13 is connected to the feed inlet 11, and the bottom of the branch flow channels 14 is connected to the top of the main flow channel 13. Each branch flow channel 14 has a corresponding branch flow channel 14. The die core 1 is connected to the top surface of the die core 1 outside the cylindrical flow channel 12, and the outer side of the bottom of the cylindrical flow channel 12 is in close contact with the die core 1. The outer side of the upper part of the cylindrical flow channel 12 is separated from the die core 1 by a gap to form an annular flow channel 5. The die 3 is connected to the top surface of the cylindrical flow channel 12, and the die adjusting ring 4 is connected to the top surface of the die core 12. An annular extrusion channel 6 is formed between the die 3 and the die adjusting ring 4. The molten raw material enters through the feed port 11, passes through the main flow channel 13 and the branch flow channel 14, and reaches the spiral groove flow channel 121. It then enters the annular extrusion channel 6 through the annular flow channel 5 and is extruded evenly.

[0020] In the above scheme, the depth of the spiral groove channel 121 gradually decreases from bottom to top, and the gap of the annular channel 5 gradually increases from bottom to top.

[0021] Furthermore, the gap at the top of the annular flow channel 5 corresponds to the gap size at the bottom of the annular extrusion channel 6.

[0022] Specifically, the annular extrusion channel 6 includes a bottom inlet section 61, a middle variable diameter section 62, and a top shaping extrusion section 63. The inlet section 61 corresponds to the annular flow channel 5. The gap between the lower and middle regions of the variable diameter section 62 gradually increases, and the gap between the middle and upper regions of the variable diameter section 62 gradually decreases. The lower region of the variable diameter section 62 is in a tapering state from bottom to top. The shaping extrusion section 63 is arranged axially to ensure that the gap in the region of the shaping extrusion section 63 remains unchanged.

[0023] In addition, the die 3 is connected to the top surface of the cylindrical flow channel 12 by a screw.

[0024] Specifically, the outer sleeve 2 of the mold core body is connected to the top surface of the mold core body 1 by screws, and the die adjusting ring 4 is connected to the top surface of the outer sleeve 2 of the mold core body by screws.

[0025] Furthermore, the feed inlet 11 is located in the center area of ​​the bottom surface of the mold core 1, the main channel 13 is vertically arranged above the feed inlet 11, and the branch channel 14 is inclined upward from the top of the main channel 13 outward.

[0026] Furthermore, the number of the spiral groove flow channel 121 and the branch flow channel 14 is 2, 4, 6 or other even number.

[0027] In this invention, the following description uses two branch channels 14 and a spiral groove channel 121 as an example. The molten raw material enters from the feed port 11, passes through the main channel 13 and enters the left and right branch channels 14. It is divided into two groups and enters the left and right spiral groove channels 121 respectively. The raw material flows upward in two spirals. After reaching the upper part of the cylindrical channel section 12, due to the gradual increase of the gap of the annular channel 5 and the gradual decrease of the depth of the spiral groove channel 121, the raw material will gradually diffuse upward in a circular shape. Finally, the raw material flows upward out of the top of the annular channel 5 and enters the inlet section 61 of the annular extrusion channel 6 in a circular shape. After passing through the upper variable diameter section 62 for buffering and stabilization, a uniform pressure annular fluid state is formed. The raw material continues to be extruded upward through the shaping extrusion section 63. The gap of the shaping extrusion section 63 corresponds to the thickness of the required extruded film to form a cylindrical film.

[0028] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, equivalent changes, or alterations made to the above embodiments based on the technical principles of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A single-layer blown film extrusion die for producing LCP films, characterized in that: The mold includes a core body (1), a core body outer sleeve (2), a die (3), and a die adjusting ring (4). The core body (1) has a feed inlet (11) at its bottom. A cylindrical flow channel (12) extends upward from the center of the top surface of the core body (1). At least two spiral groove flow channels (121) are provided on the outer side of the cylindrical flow channel (12) from bottom to top. The lower and upper ends of the spiral groove flow channels (121) are evenly distributed at equal angles along the circumference. The core body (1) has a main flow channel (13) and at least two branch flow channels (14). The bottom of the main flow channel (13) is connected to the feed inlet (11), and the bottom of the branch flow channels (14) is connected to the top of the main flow channel (13). The top of each branch flow channel (14) is connected to the lower end of one of the spiral groove flow channels (121). The head is connected, the outer sleeve of the mold core (2) is connected to the top surface of the mold core (1) outside the cylindrical flow channel (12), the bottom outer side of the cylindrical flow channel (12) is tightly fitted with the outer sleeve of the mold core (2), and there is a gap between the upper outer side of the cylindrical flow channel (12) and the outer sleeve of the mold core (2) to form an annular flow channel (5); the die (3) is connected to the top surface of the cylindrical flow channel (12), the die adjusting ring (4) is connected to the top surface of the outer sleeve of the mold core (2), and an annular extrusion channel (6) is formed between the die (3) and the die adjusting ring (4); the molten raw material enters through the feed port (11), passes through the main channel (13) and the branch channel (14) and reaches the spiral groove channel (121), and enters the annular extrusion channel (6) through the annular flow channel (5) and is then uniformly extruded.

2. The single-layer blown film extrusion die for producing LCP films according to claim 1, characterized in that: The depth of the spiral groove channel (121) gradually decreases from bottom to top, and the gap of the annular channel (5) gradually increases from bottom to top.

3. The single-layer blown film extrusion die for producing LCP films according to claim 1, characterized in that: The gap at the top of the annular flow channel (5) corresponds to the gap size at the bottom of the annular extrusion channel (6).

4. A single-layer blown film extrusion die for producing LCP films according to claim 1, characterized in that: The annular extrusion channel (6) includes a bottom inlet section (61), a middle variable diameter section (62), and a top shaping extrusion section (63). The inlet section (61) corresponds to the annular flow channel (5). The gap between the lower and middle regions of the variable diameter section (62) gradually increases, and the gap between the middle and upper regions of the variable diameter section (62) gradually decreases. The lower region of the variable diameter section (62) is in a tapering state from bottom to top. The shaping extrusion section (63) is arranged axially.

5. A single-layer blown film extrusion die for producing LCP films according to claim 1, characterized in that: The die (3) is connected to the top surface of the cylindrical flow channel (12) by a screw.

6. A single-layer blown film extrusion die for producing LCP films according to claim 1, characterized in that: The outer sleeve (2) of the mold core body is connected to the top surface of the mold core body (1) by screws, and the die adjusting ring (4) is connected to the top surface of the outer sleeve (2) of the mold core body by screws.

7. A single-layer blown film extrusion die for producing LCP films according to claim 1, characterized in that: The feed inlet (11) is located in the center area of ​​the bottom surface of the mold core (1), the main channel (13) is vertically arranged above the feed inlet (11), and the branch channel (14) is inclined upward from the top of the main channel (13) outward.

8. A single-layer blown film extrusion die for producing LCP films according to claim 1, characterized in that: The number of the spiral groove channel (121) and the branch channel (14) is 2, 4, 6 or other even number.

Images