A biaxial stretching process for pre-coating film for base film coating

Abstract

The present invention relates to a biaxial stretching process for a pre-coated film for a base film coating applied in the field of film stretching. During the biaxial stretching process, a pre-coating unit and a detection unit are used in conjunction to perform a marking coating on the base film before stretching. By analyzing the change of the mark each time the film is stretched, it is possible to effectively determine whether the stretching is uniform, and to promptly detect the occurrence of uneven stretching, thereby effectively ensuring the quality of the film stretching, and effectively avoiding the occurrence of batches of unqualified films, thereby reducing the waste of materials. At the same time, under the setting of a special preheating roller, the uniformity of the heat distribution on the surface of the preheating roller can be monitored, and the uneven temperature distribution can be detected in time, thereby effectively avoiding the occurrence of uneven stretching, and facilitating the staff to take timely countermeasures to the situation, thereby further improving the quality of the film after stretching.

Description

Technical Field

[0001] The present invention relates to a biaxial stretching process for a film, in particular to a biaxial stretching process for a pre-coated film for a base film coating applied in the field of film stretching. Background Art

[0002] During film production, the film is typically melted, then extruded through an extruder, and finally stretched into shape. Conventional film biaxial stretching typically involves sequentially stretching the film longitudinally and transversely through a longitudinal stretching machine and a transverse stretching machine. Following biaxial stretching, the film is heat-set, and finally, the film's stretching uniformity is tested.

[0003] However, this method is prone to a problem. When abnormal film stretching is subsequently detected, a batch of products often have the problem of uneven stretching, resulting in a significant increase in the scrap rate and waste of materials. Summary of the Invention

[0004] In view of the above-mentioned prior art, the technical problem to be solved by the present invention is that the method of stretching first and then testing, when there is a problem with stretching uniformity, it is easy to cause batches of films to be abnormal and the scrap rate to increase significantly.

[0005] To solve the above problems, the present invention provides a biaxial stretching process for a pre-coating film for a base film coating, comprising the following steps:

[0006] S1, the base film extruded from the extruder is wound up by a winding assembly, and a pre-coating unit and a detection unit are respectively set on the front and rear sides of the longitudinal stretching machine, and a detection unit is also set on the rear side of the longitudinal stretching machine;

[0007] S2, introducing the wound base film into the longitudinal stretching machine, passing the base film through the pre-coating unit and then into the longitudinal stretching machine, and performing a color ribbon coating process on both sides of the base film at intervals by the pre-coating unit, and then performing a longitudinal stretching process, and after stretching, comparing the stretching conditions of the two color ribbons by the detection unit;

[0008] S3. When the detection unit confirms that the changes of the two color ribbons are synchronized, it means that the stretching is uniform. At this time, the base film that has been stretched longitudinally is further stretched transversely, and then the stretching conditions of the two color ribbons are compared again through the detection unit;

[0009] S4. When the changes of the two color bands are still synchronized after transverse stretching, it means that the base film is stretched evenly. At this time, continue with the heat setting treatment:

[0010] S5. Finally, trimming is performed to remove the ribbon, followed by winding and slitting to complete biaxial stretching;

[0011] The pre-coating unit includes two coating columns located on both sides of the base film, each of which includes a base, a coating arm fixedly connected to the upper end of the base, and a film clamping unit installed at one end of the coating arm close to the other coating arm. The film clamping unit includes a reverse coating block fixed to the coating arm and a dynamic pressure plate connected to the coating arm via an electric slide rail. The dynamic pressure plate is located above the reverse coating block.

[0012] The detection unit includes two high-definition cameras, which are respectively installed at the rear end of the longitudinal stretching equipment and just above the discharge port at the rear end of the transverse stretching equipment.

[0013] In the above-mentioned biaxial stretching process of the pre-coated film for the base film coating, during the biaxial stretching process, the base film can be marked and coated by using the pre-coating unit and the detection unit in conjunction with each other before stretching. By analyzing the changes in the mark each time it is stretched, it can be effectively judged whether the stretching is uniform, which facilitates timely detection of uneven stretching, thereby effectively ensuring the quality of film stretching.

[0014] As a further improvement of the present application, the retrograde coating block includes a carrying plate, a fixed coating plate fixedly connected to the carrying plate, and a sponge coating layer fixedly embedded in the middle of the upper end of the fixed coating plate. The fixed coating plate is provided with a liquid storage cavity, two drainage holes and a transition liquid tank matching the sponge coating layer. The two drainage holes are respectively located on the left and right sides of the liquid storage cavity, and the two liquid storage cavities are respectively connected to the transition liquid tank and the bottom of the liquid storage cavity.

[0015] As a further improvement of the present application, the liquid storage chamber is filled with colored liquid, a liquid pushing plate is placed inside the liquid storage chamber, and an electric push rod is connected between the upper end of the liquid pushing plate and the top end of the liquid storage chamber.

[0016] As a further improvement of the present application, a liquid-conducting fluff layer is fixedly connected to the lower end of the sponge coating layer. The liquid-conducting fluff layer does not contact the bottom surface of the transition liquid tank. Both the liquid-conducting fluff layer and the sponge coating layer are made of water-absorbing materials, and a liquid level sensor is installed inside the transition liquid tank.

[0017] As another improvement of the present application, the preheating rollers of the transverse stretching equipment and the longitudinal stretching equipment both include a roller body, an outer sleeve wrapped around the outer end of the roller body, and two brackets connected to the two ends of the roller body through an electric rotating shaft. A plurality of detection grooves distributed vertically and horizontally are opened on the outer end of the roller body, and the parts of the outer sleeve corresponding to the detection grooves are embedded in the detection grooves. A heat-sensing unit is provided on the bracket and the roller body.

[0018] As another improved supplement to the present application, the thermal sensing unit includes a plurality of thermal strips respectively fixedly connected in the detection groove and a laser rangefinder fixedly installed on one of the brackets close to one end of the roller body. The plurality of thermal strips are distributed in a circular array, and the distance between the central axis of the laser rangefinder and the central axis of the outer sleeve is the same as the distance between the central axis of the plurality of thermal strips and the central axis of the outer sleeve.

[0019] As another improved supplement of the present application, the detection groove is filled with a hot-melt filler, and the hot-melt temperature of the hot-melt filler is consistent with the preset temperature of the corresponding preheating roller.

[0020] As another improved supplement to the present application, the thermal strip includes two positioning segments respectively fixedly connected to the two vertical inner walls of the detection groove, a pre-blocking segment located between the two positioning segments, and two connecting ropes respectively fixedly connected between the two positioning segments and the pre-blocking segments, and the connecting ropes are in a relaxed state.

[0021] As another improvement supplement to the present application, the positioning section and the outer sleeve are made of high-temperature resistant transparent materials, the pre-blocking section is an opaque structure, and when the detection slot is facing directly downward, in the absence of resistance, when the pre-blocking section naturally droops, the pre-blocking section is lower than the central axis of the laser rangefinder.

[0022] In summary, during the biaxial stretching process, through the coordinated use of the pre-coating unit and the detection unit, the base film can be marked and coated before stretching. By analyzing the changes in the mark each time the stretching is performed, it can be effectively determined whether the stretching is uniform, so that uneven stretching can be detected in time, thereby effectively ensuring the quality of the film stretching, and effectively avoiding the occurrence of unqualified batches of films, reducing material waste. At the same time, the thermal unit can also monitor the uniformity of heat distribution on the surface of the preheating roller, and can detect uneven temperature distribution in time, thereby effectively avoiding uneven stretching, so that the staff can take timely countermeasures to the uneven heat distribution of the preheating roller, and further improve the quality of the film after stretching. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the main flow chart of the first embodiment of this application;

[0024] Figure 2 This is a schematic diagram of the stretching uniformity detection according to the first embodiment of the present application;

[0025] Figure 3 Schematic diagram of the first embodiment of the present application before and after the edge trimming process;

[0026] Figure 4 This is a three-dimensional diagram of a marking column according to the first embodiment of the present application;

[0027] Figure 5 This is a cross-sectional view of the liquid receiving plate according to the first embodiment of the present application;

[0028] Figure 6 This is a schematic diagram of the first embodiment of the present application when the liquid receiving plate supplies liquid to the coating layer;

[0029] Figure 7This is a schematic diagram of coating a color ribbon on the edge of a base film in the first embodiment of the present application;

[0030] Figure 8 This is a schematic diagram of the first embodiment of the present application after the base film edge color band is formed;

[0031] Figure 9 This is a cross-sectional view of a preheating roller according to a second embodiment of the present application;

[0032] Figure 10 This is a comparison diagram of the heat distribution of the thermal unit of the second embodiment of the present application under different conditions of heat on the surface of the preheating roller.

[0033] Description of the numbers in the figure:

[0034] 1 base, 2 coating arm, 3 retrograde coating block, 301 liquid storage chamber, 302 drainage hole, 303 transition liquid tank, 31 bearing plate, 32 fixed coating plate, 33 sponge coating layer, 4 dynamic pressure plate, 51 electric push rod, 52 liquid pushing plate, 6 liquid guiding villi layer, 71 roller body, 72 external sleeve, 73 bracket, 8 thermal strip, 81 positioning section, 82 pre-shielding section, 83 connecting rope, 9 laser rangefinder. DETAILED DESCRIPTION

[0035] Two implementation modes of the present application are described in detail below with reference to the accompanying drawings.

[0036] The first implementation method:

[0037] Figure 1 A biaxial stretching process for a pre-coating film for a base film coating is shown, comprising the following steps:

[0038] S1, the base film extruded from the extruder is wound up by a winding assembly, and a pre-coating unit and a detection unit are respectively set on the front and rear sides of the longitudinal stretching machine, and a detection unit is also set on the rear side of the longitudinal stretching machine;

[0039] S2, introducing the wound base film into the longitudinal stretching machine, passing the base film through the pre-coating unit and then into the longitudinal stretching machine, and performing a color ribbon coating process on both sides of the base film at intervals by the pre-coating unit, and then performing a longitudinal stretching process, and after stretching, comparing the stretching conditions of the two color ribbons by the detection unit;

[0040] S3, such as Figure 2 When the detection unit confirms that the changes of the two color ribbons are synchronized, it means that the stretching is uniform. At this time, the base film that has been stretched longitudinally continues to be stretched transversely, and then the stretching conditions of the two color ribbons are compared again through the detection unit;

[0041] S4. When the changes of the two color bands are still synchronized after transverse stretching, it means that the base film is stretched evenly, and then continue with the heat setting treatment:

[0042] S5, such as Figure 3 , and finally perform trimming to remove the ribbon, and then perform winding and slitting to complete biaxial stretching;

[0043] Among them, the pre-coating unit includes two coating columns located on both sides of the base film, the coating column includes a base 1, a coating arm 2 fixedly connected to the upper end of the base 1, and a film clamping unit installed on the coating arm 2 near one end of the other coating arm 2, the film clamping unit includes a retrograde coating block 3 fixed to the coating arm 2 and a dynamic pressure plate 4 connected to the coating arm 2 through an electric slide rail, and the dynamic pressure plate 4 is located above the retrograde coating block 3; the detection unit includes a high-definition camera, and the two high-definition cameras are respectively installed at the rear end of the longitudinal stretching equipment and directly above the discharge port at the rear end of the transverse stretching equipment.

[0044] It is also worth noting that a high-definition camera can be installed on the top of the detection unit in front of the longitudinal stretching equipment to obtain the initial shape of the ribbon. The changes in the ribbon can then be directly compared with the initial shape for detection. After transverse stretching, the edge of the ribbon can be detected with higher accuracy. At the same time, if the initial shape obtained is different from the expected rectangle and there is any defect, the ribbon can be re-coated to prevent subsequent detection results from being easily affected.

[0045] like Figure 4 and Figure 5 The retrograde coating block 3 includes a carrying plate 31, a fixed coating plate 32 fixedly connected to the carrying plate 31, and a sponge coating layer 33 fixedly embedded in the middle of the upper end of the fixed coating plate 32. The lower end of the sponge coating layer 33 is fixedly connected to a liquid-conducting fluff layer 6. The liquid-conducting fluff layer 6 does not contact the bottom surface of the transition liquid tank 303, and the liquid-conducting fluff layer 6 and the sponge coating layer 33 are both made of water-absorbing materials. The fixed coating plate 32 is internally provided with a liquid storage cavity 301, two drainage holes 302 and A transition liquid tank 303 is matched with the sponge coating layer 33, a liquid level sensor is installed in the transition liquid tank 303, two drainage holes 302 are respectively located on the left and right sides of the liquid storage chamber 301, and the two liquid storage chambers 301 are respectively connected to the transition liquid tank 303 and the bottom of the liquid storage chamber 301, the liquid storage chamber 301 is filled with colored liquid, a liquid push plate 52 is placed inside the liquid storage chamber 301, and an electric push rod 51 is connected between the upper end of the liquid push plate 52 and the top of the liquid storage chamber 301. Figure 6 When the film needs to be coated, the electric push rod 51 can be used to control the liquid pushing plate 52 to move downward to squeeze the colored solution so that it enters the transition liquid tank 303 along the drainage hole 302. The liquid level sensor can effectively control the liquid level therein to prevent it from contacting the sponge coating layer 33. At the same time, the liquid-guiding fluff layer 6 can be partially immersed in the liquid surface, so that the sponge coating layer 33 can absorb the colored liquid. Figure 7-8At this time, the dynamic pressure plate 4 is controlled to move downward by the electric slide rail, so that the dynamic pressure plate 4 and the sponge coating layer 33 are in conflict with each other across the base film. As the base film moves, the coating operation occurs. When the expected coating length is reached, the dynamic pressure plate 4 is controlled to separate from the reverse coating block 3 by the electric slide rail, so that the base film, the reverse coating block 3 and the dynamic pressure plate 4 are independent of each other and do not contact each other, so that the coating of the color ribbon on the base film by the reverse coating block 3 can be reflected as discontinuous.

[0046] It is worth noting that after the colored liquid enters the transition liquid tank 303, the liquid level sensor controls the liquid level to prevent it from contacting the sponge coating layer 33 and to be higher than the lower end surface of the liquid-conducting fluff layer 6, so that the sponge coating layer 33 does not adsorb too much colored liquid, thereby effectively ensuring that the color ribbon formed on the base film is not prone to dripping, dripping or blurred edges due to excessive content of colored liquid, thereby making the color ribbon uniform, so that the subsequent comparison of the changes in two corresponding color ribbons can increase the accuracy of judging whether the stretching is uniform.

[0047] In the above-mentioned biaxial stretching process of the pre-coated film for the base film coating, during the biaxial stretching process, the base film can be marked and coated by using the pre-coating unit and the detection unit in conjunction with each other before stretching. By analyzing the changes in the mark each time it is stretched, it can be effectively judged whether the stretching is uniform, which facilitates timely detection of uneven stretching, thereby effectively ensuring the quality of film stretching.

[0048] The second implementation method:

[0049] Based on the first embodiment, this embodiment adds a thermal sensing unit for detecting the heat uniformity distribution of the preheating roller and a laser rangefinder 9, and the rest of the parts remain the same as the first embodiment.

[0050] Figure 9 The preheating rollers of the transverse stretching equipment and the longitudinal stretching equipment shown include a roller body 71, an outer sleeve 72 wrapped around the outer end of the roller body 71, and two brackets 73 connected to the two ends of the roller body 71 via an electric rotating shaft. The outer end of the roller body 71 is bored with multiple detection grooves distributed vertically and horizontally. The portion of the outer sleeve 72 corresponding to the detection groove is embedded in the detection groove. A heat-sensing unit is provided on the bracket 73 and the roller body 71. The heat-sensing unit includes multiple thermal strips 8 fixedly connected to the detection grooves and a laser rangefinder 9 fixedly installed on one of the brackets 73 near one end of the roller body 71. The multiple thermal strips 8 are distributed in a circular array, and the distance between the central axis of the laser rangefinder 9 and the central axis of the outer sleeve 72 is the same as the distance between the central axis of the multiple thermal strips 8 and the central axis of the outer sleeve 72. As the preheating roller rotates, when the detection groove rotates to the bottom and faces the laser rangefinder 9, the light emitted by the laser rangefinder 9 is just facing the thermal strips 8, so that the data on the laser rangefinder 9 is larger than when it is irradiated at a position other than the detection groove.

[0051] The thermal strip 8 includes two positioning segments 81 respectively fixedly connected to the two vertical inner walls of the detection groove, a pre-shielding segment 82 located between the two positioning segments 81, and two connecting ropes 83 respectively fixedly connected between the two positioning segments 81 and the pre-shielding segment 82. The connecting ropes 83 are in a relaxed state, so that the pre-shielding segment 82 can droop in a natural state and be misaligned with the positioning segment 81.

[0052] The positioning section 81 and the outer sleeve 72 are both made of high-temperature resistant transparent materials. The pre-shielding section 82 is an opaque structure. When the detection notch is facing directly downward, when there is no resistance, the pre-shielding section 82 naturally droops and is lower than the central axis of the laser rangefinder 9, so that the surface temperature of the preheating roller reaches the preset temperature. When the heat is evenly distributed, the pre-shielding section 82 does not block the laser light of the laser rangefinder 9, so that the distance data detected by the laser rangefinder 9 is clearly distinguished, which makes it easier for the staff to judge the heat distribution on the surface of the preheating roller based on the data.

[0053] The detection tank is filled with hot melt filler, and the hot melt temperature of the hot melt filler is consistent with the preset temperature of the corresponding preheating roller. Figure 10 When the heat distribution on the surface of the preheating roller is uniform and the temperature is normal, the hot-melt filler is in a hot-melt state and has fluidity. The pre-shielding section 82 can move in the detection tank under the action of gravity. When the detection tank rotates to the bottom with the preheating roller, the pre-shielding section 82 sinks. At this time, it does not block the light beam of the laser rangefinder 9, and the distance data measured by it is the largest.

[0054] When there is a local uneven heat distribution, the hot-melt filler in the lower temperature part has weak fluidity and will harden locally because it is lower than the hot-melt temperature, so that the pre-shielding section 82 cannot sink completely and presents a certain tilt state, resulting in a decrease in the data on the laser rangefinder 9;

[0055] When the detection slot is located directly above, the pre-blocking section 82 will fall back and be located between the two positioning sections 81. At this time, the light beam of the laser rangefinder 9 can be directly blocked, and the data on the laser rangefinder 9 is minimum.

[0056] In summary, during the biaxial stretching process, through the coordinated use of the pre-coating unit and the detection unit, the base film can be marked and coated before stretching. By analyzing the changes in the mark each time the stretching is performed, it can be effectively determined whether the stretching is uniform, so that uneven stretching can be detected in time, thereby effectively ensuring the quality of the film stretching, and effectively avoiding the occurrence of unqualified batches of films, reducing material waste. At the same time, the thermal unit can also monitor the uniformity of heat distribution on the surface of the preheating roller, and can detect uneven temperature distribution in time, thereby effectively avoiding uneven stretching, so that the staff can take timely countermeasures to the uneven heat distribution of the preheating roller, and further improve the quality of the film after stretching.

[0057] In view of current actual needs, the protection scope of the above-mentioned implementation mode adopted in this application is not limited to this. Various changes made within the knowledge scope of technical personnel in this field without departing from the concept of this application still fall within the protection scope of the present invention.

Claims

1. A biaxial stretching process for a pre-coating film for a base film coating, characterized in that: The following steps are involved: S1, the base film extruded from the extruder is wound up by a winding assembly, and a pre-coating unit and a detection unit are respectively set on the front and rear sides of the longitudinal stretching machine, and a detection unit is also set on the rear side of the transverse stretching machine; S2, introducing the wound base film into the longitudinal stretching machine, passing the base film through the pre-coating unit and then into the longitudinal stretching machine, and performing a color ribbon coating process on both sides of the base film at intervals by the pre-coating unit, and then performing a longitudinal stretching process, and after stretching, comparing the stretching conditions of the two color ribbons by the detection unit; S3. When the detection unit confirms that the changes of the two color ribbons are synchronized, it means that the stretching is uniform. At this time, the base film that has been stretched longitudinally is further stretched transversely, and then the stretching conditions of the two color ribbons are compared again through the detection unit; S4. When the changes of the two color bands are still synchronized after transverse stretching, it means that the base film is stretched evenly, and then continue with the heat setting treatment: S5. Finally, trimming is performed to remove the ribbon, followed by winding and slitting to complete biaxial stretching; The pre-coating unit comprises two marking columns respectively located on both sides of the base film, the marking column comprising a base (1), a coating arm (2) fixedly connected to the upper end of the base (1), and a film clamping unit installed on the coating arm (2) at one end close to the other coating arm (2), the film clamping unit comprising a reverse coating block (3) fixed to the coating arm (2) and a dynamic pressure plate (4) connected to the coating arm (2) via an electric slide rail, and the dynamic pressure plate (4) is located above the reverse coating block (3); The detection unit includes a high-definition camera, and two high-definition cameras are respectively installed on the rear end of the longitudinal stretching device and directly above the discharge port of the rear end of the transverse stretching device; The preheating rollers of the transverse stretching equipment include a roller body (71), an outer sleeve (72) wrapped around the outer end of the roller body (71), and two brackets (73) connected to the two ends of the roller body (71) through an electric rotating shaft. The outer end of the roller body (71) is provided with a plurality of detection grooves distributed vertically and horizontally. The portion of the outer sleeve (72) corresponding to the detection groove is embedded in the detection groove. A heat-sensing unit is provided on the bracket (73) and the roller body (71). The heat-sensing unit includes a plurality of heat-sensitive strips (8) respectively fixedly connected in the detection groove and a laser rangefinder (9) fixedly installed on one end of one of the brackets (73) close to the roller body (71). The plurality of heat-sensitive strips (8) are annular. The laser rangefinder (9) is distributed in an array, and the distance between the central axis of the laser rangefinder (9) and the central axis of the outer sleeve (72) is the same as the distance between the central axis of the plurality of thermal strips (8) and the central axis of the outer sleeve (72). The detection groove is filled with a hot melt filler, and the hot melt temperature of the hot melt filler is consistent with the preset temperature of the corresponding preheating roller. The thermal strip (8) includes two positioning segments (81) respectively fixedly connected to the two vertical inner walls of the detection groove, a pre-shielding segment (82) located between the two positioning segments (81), and two connecting ropes (83) respectively fixedly connected between the two positioning segments (81) and the pre-shielding segment (82), and the connecting ropes (83) are in a relaxed state.

2. The biaxial stretching process for a pre-coating film for a base film coating according to claim 1, characterized in that: The retrograde coating block (3) comprises a carrier plate (31), a fixed coating plate (32) fixedly connected to the carrier plate (31), and a sponge coating layer (33) fixedly embedded in the middle of the upper end of the fixed coating plate (32), wherein the fixed coating plate (32) is provided with a liquid storage cavity (301), two drainage holes (302) and a transition liquid tank (303) matching the sponge coating layer (33), the two drainage holes (302) are respectively located on the left and right sides of the liquid storage cavity (301), and the two liquid storage cavities (301) are respectively connected to the transition liquid tank (303) and the bottom of the liquid storage cavity (301).

3. The biaxial stretching process for a pre-coating film for a base film coating according to claim 2, characterized in that: The liquid storage chamber (301) is filled with colored liquid, a liquid pushing plate (52) is placed inside the liquid storage chamber (301), and an electric push rod (51) is connected between the upper end of the liquid pushing plate (52) and the top end of the liquid storage chamber (301).

4. The biaxial stretching process for a pre-coating film for a base film coating according to claim 3, characterized in that: The lower end of the sponge coating layer (33) is fixedly connected to a liquid-conducting fluff layer (6), the liquid-conducting fluff layer (6) does not contact the bottom surface of the transition liquid tank (303), and the liquid-conducting fluff layer (6) and the sponge coating layer (33) are both made of water-absorbing materials. A liquid level sensor is installed inside the transition liquid tank (303).

5. The biaxial stretching process for a pre-coating film for a base film coating according to claim 1, characterized in that: The positioning section (81) and the outer sleeve (72) are both made of a high-temperature resistant transparent material. The pre-shielding section (82) is an opaque structure. When the detection notch portion faces directly downward, in the absence of resistance, when the pre-shielding section (82) naturally droops, the pre-shielding section (82) is lower than the central axis of the laser rangefinder (9).

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