High-barrier lining bag production device and production process thereof

Abstract

The invention relates to the technical field of lining bag production, and discloses a high-barrier lining bag production device which comprises a ground, an extrusion assembly is arranged on the upper side of the ground, a first support is fixedly connected to the upper surface of the ground, a second support is fixedly connected to the upper side of the first support, and a three-legged electricity removal frame is fixedly connected to the interior of the first support. A limiting ring is fixedly connected into the first support, a grounding assembly is arranged on the side wall of the second support, a first transmission roller and a second transmission roller are rotationally connected into the second support, a guiding assembly is arranged outside the second support, and a winding machine is fixedly connected to the upper side of the ground. The extrusion assembly is started to blow out a cylindrical film blank composed of the ethylene-vinyl alcohol copolymer, the bonding resin and the modified polyethylene added with a small amount of the food-grade antistatic master batch, so that the effect of preparing the lining bag with high gas barrier and no electrostatic charge residue can be achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of inner liner bag production, in particular to a high-barrier inner liner bag production device and production process thereof. BACKGROUND

[0002] Inner liner bag production refers to a process of producing bag-shaped packaging products with waterproof, moisture-proof, anti-leakage, barrier or sealing functions by using polyethylene, polypropylene, polyamide, polyvinyl alcohol and other high molecular materials as main raw materials, combining different use requirements, and through a series of processes such as raw material pretreatment, film extrusion molding, compounding, printing, bag making, cutting, and testing. It is widely used in food, chemical, pharmaceutical, electronic, agricultural product and other fields to protect the contents from the external environment. The inner liner bag for packaging liquid needs to strengthen the heat sealing strength to prevent leakage, while the inner liner bag for packaging precision electronic components must have anti-static function, and attention should be paid to the environmental protection and safety of raw materials to avoid harmful substance migration.

[0003] Related inner liner bag production can achieve basic barrier and protection functions through multi-layer co-extrusion blown film process, but the related process has single material function and insufficient static control, which leads to easy residual static charge of the inner liner bag, unstable barrier performance, and affects the packaging safety of high sensitive contents. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application provides a high-barrier inner liner bag production device and production process thereof, which solves the problem of easy residual static charge of the inner liner bag, unstable barrier performance, and affects the packaging safety of high sensitive contents caused by the related inner liner bag production adopting multi-layer co-extrusion blown film process.

[0005] To achieve the above purpose, the present application realizes the following technical scheme: a high-barrier inner liner bag production device and production process thereof, comprising a ground, an extrusion assembly is arranged on the upper side of the ground, a support one is fixedly connected to the upper surface of the ground, a support two is fixedly connected to the upper side of the support one, a three-legged static eliminator is fixedly connected to the inside of the support one, a limiting ring is fixedly connected to the inside of the support one, a grounding assembly is arranged on the side wall of the support two, a transmission roller one and a transmission roller two are rotatably connected to the inside of the support two, a guide assembly is arranged on the outside of the support two, and a winding machine is fixedly connected to the upper side of the ground.

[0006] By adopting the technical scheme, after starting the extrusion assembly, the ethylene-vinyl alcohol copolymer, the adhesive resin and the modified polyethylene mixed with the food-grade antistatic master batch are blown out together; then, the tubular film blank passes through the limiting ring and the three-legged electric-removing frame in turn, wherein the limiting ring contacts the surface of the film blank to accelerate its cooling and shaping and inhibit excessive expansion; while the three-legged electric-removing frame extrudes the film blank to gradually flatten it into a sheet shape, the three-legged electric-removing frame forms a grounding loop with the ground through the support one, and then guides and removes the accumulated electric charge on the surface of the film blank; thereafter, the sheet-shaped film blank is guided to further shape by the transmission roller one and the transmission roller two, and is continuously moved by the grounding assembly; then, the grounding assembly is grounded through the support two and the support one, and further eliminates the residual electric charge on the surface of the film blank; finally, the film blank is conveyed to the winding machine to complete the winding and shaping, and the inner liner bag with high gas barrier property and no static residual is prepared.

[0007] Preferably, the extrusion assembly comprises a co-extrusion die, the upper side of the ground is fixedly connected with the co-extrusion die, the inside of the co-extrusion die is fixedly connected with a blow die head, the upper side of the ground is fixedly connected with a spiral feeder, and the outside of the spiral feeder is connected with the outside of the co-extrusion die.

[0008] Preferably, the grounding assembly comprises a driving motor one, the side wall of the support two is fixedly connected with the driving motor one, the output end of the driving motor one is connected with a rotating column, and the outside of the rotating column is fixedly connected with a contact block.

[0009] Preferably, the guiding assembly comprises a guiding roller one, the outside of the guiding roller one is rotatably connected in the inside of the support two, and the inside of the support one is rotatably connected with a guiding roller two and a guiding roller three.

[0010] Preferably, the upper side of the ground is fixedly connected with a fixed block one, the outside of the fixed block one is fixedly connected with a driving motor two, the output end of the driving motor two is connected with a transmission roller three, and the outside of the transmission roller three is rotatably connected in the inside of the fixed block one.

[0011] Preferably, the upper surface of the ground is fixedly connected with a fixed block two, the side wall of the fixed block two is fixedly connected with a storage tank, the inside of the storage tank is provided with a spray head, the inside of the storage tank is rotatably connected with a rotating rod, the outside of the rotating rod is fixedly connected with a stirring block, the side wall of the rotating rod is provided with a conveyor belt, and the side wall of the conveyor belt is arranged outside the transmission roller three.

[0012] Preferably, the three-legged electric-removing frame and the limiting ring are both made of copper-aluminum alloy.

[0013] Preferably, the rotating column and the contact block are both made of stainless steel.

[0014] Preferably, a production process of a high-barrier inner liner bag production device comprises the following steps:

[0015] S1, raw material preparation and co-extrusion: the high molecular raw material is conveyed to the co-extrusion die through the screw feeder, and is extruded into a cylindrical film blank through the blow die head;

[0016] S2, cooling and shaping: the cylindrical film blank is preliminarily shaped by air cooling to form a stable film tube;

[0017] S3, static elimination and guidance: the film tube passes through the three-legged static eliminator to eliminate static electricity, and is preliminarily positioned by the limiting ring, and then is guided in the transmission direction by the transmission roller one and the transmission roller two;

[0018] S4, grounding treatment: the rotating column and the contact block are rotated by the driving motor one in the grounding assembly to continuously contact the film surface, and further discharge the residual static electricity;

[0019] S5, surface treatment and winding: the film material is tensioned and transmitted to the transmission roller three by the guide roller one, the guide roller two and the guide roller three, then the surface treatment agent is sprayed by the spray head, and finally is wound into a roll by the winding machine.

[0020] Preferably, in the step S5, when the surface treatment agent is sprayed, the stirring block in the storage tank is driven by the rotating rod to continuously uniformly stir the surface treatment agent; wherein the surface treatment agent is a polyurethane-acrylic composite emulsion.

[0021] Working principle: the present application synchronously extrudes and blow-molds multiple layers of high molecular materials by the co-extrusion die and the blow die head to form a cylindrical film blank with basic barrier and antistatic properties; then the limiting ring constrains the shape of the film blank and accelerates the cooling to provide a dimensionally stable substrate for subsequent processing; and the three-legged static eliminator preliminarily discharges static electricity from the film surface by virtue of the conductivity of the copper-aluminum alloy material;

[0022] Then the device continuously adheres to the film surface in rotation by the stainless steel contact block in the grounding assembly to further discharge the residual static electricity to the ground, ensuring that the film material is in a non-static state; and the transmission roller and the guide roller work together to maintain the smooth transmission of the film material and control its direction, providing uniform tension and stable travel path for the surface treatment stage;

[0023] At the same time, the stirring block is driven by the transmission roller three to keep the polyurethane-acrylic composite emulsion in a uniform suspended state, and the emulsion is sprayed on the film surface through the spray head; at this time, the transmission roller three pulls the film material while pressing it, so as to make the functional coating and the substrate tightly combined to form a dense composite barrier layer, and finally the high-performance inner liner bag roll material is formed by the winding machine.

[0024] The present application provides a high-barrier inner liner bag production device and its production process, which has the following beneficial effects:

[0025] 1. The application starts to blow the cylindrical film blank composed of ethylene-vinyl alcohol copolymer, adhesive resin and a small amount of food-grade antistatic master batch modified polyethylene, wherein the ethylene-vinyl alcohol copolymer is used to provide gas barrier properties for the inner liner bag, and the modified polyethylene with a small amount of food-grade antistatic master batch is used to provide antistatic properties for the inner liner bag, and then the cylindrical film blank is sequentially passed through the limiting ring and the three-legged electric field frame, so that the inner liner bag with high gas barrier and no static charge residue can be obtained.

[0026] 2. The application drives the driving motor two to drive the transmission roller three to rotate in the fixed block one, at this time the mold blank is further extruded and transported to the winding machine under the driving of the transmission roller three, in this process the transmission roller three drives the rotating rod along the inside of the storage tank through the conveyor belt, so that the effect of ensuring uniform spraying of the composite emulsion and forming a dense coating on the surface of the inner liner bag, further enhancing the high barrier property and antistatic property of the inner liner bag can be achieved.

[0027] 3. The application drives the transmission roller three to rotate by the driving motor two, and the film material smoothly passes under the nozzle; at the same time the transmission roller three drives the rotating rod and the stirring block in the storage tank through the conveyor belt, so that the effects of improving the gas barrier property, surface uniformity and antistatic property of the inner liner bag, and ensuring the consistency of the winding product quality can be achieved. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 A three-dimensional structure schematic diagram of a high-barrier inner liner bag production device is proposed for the application;

[0029] Figure 2 A blow molding head partial structure schematic diagram of a high-barrier inner liner bag production device is proposed for the application;

[0030] Figure 3 A three-legged electric field frame partial structure schematic diagram of a high-barrier inner liner bag production device is proposed for the application;

[0031] Figure 4 A transmission roller one partial structure schematic diagram of a high-barrier inner liner bag production device is proposed for the application;

[0032] Figure 5 A guide roller three partial structure schematic diagram of a high-barrier inner liner bag production device is proposed for the application;

[0033] Figure 6 A transmission roller three partial structure schematic diagram of a high-barrier inner liner bag production device is proposed for the application;

[0034] Figure 7 A conveyor belt partial structure schematic diagram of a high-barrier inner liner bag production device is proposed for the application;

[0035] Figure 8 A flowchart of a production process of a high-barrier inner liner bag production device according to the present application is shown.

[0036] Wherein, 1, ground; 2, extrusion assembly; 201, co-extrusion die; 202, blow die head; 203, screw feeder; 3, support one; 4, support two; 5, three-legged electric field removal frame; 6, limiting ring; 7, grounding assembly; 701, drive motor one; 702, rotating column; 703, contact block; 8, transmission roller one; 9, transmission roller two; 10, guide assembly; 1001, guide roller one; 1002, guide roller two; 1003, guide roller three; 11, fixed block one; 12, drive motor two; 13, transmission roller three; 14, fixed block two; 15, storage tank; 16, nozzle; 17, conveyor belt; 18, rotating rod; 19, stirring block; 20, winding machine. DETAILED DESCRIPTION

[0037] The technical solutions of the present application will be described clearly and completely below in combination with the drawings of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0038] Please refer to the drawings of the present application Figure 1 - the drawings of the present application Figure 4 The present application provides a high-barrier inner liner bag production device and its production process, which comprises a ground 1, an extrusion assembly 2 is arranged on the upper side of the ground 1, a support one 3 is fixedly connected to the upper surface of the ground 1, a support two 4 is fixedly connected to the upper side of the support one 3, a three-legged electric field removal frame 5 is fixedly connected in the support one 3, a limiting ring 6 is fixedly connected in the support one 3, a grounding assembly 7 is arranged on the side wall of the support two 4, a transmission roller one 8 and a transmission roller two 9 are rotatably connected in the support two 4, a guide assembly 10 is arranged on the outside of the support two 4, and a winding machine 20 is fixedly connected to the upper side of the ground 1.

[0039] Specifically, by starting the extrusion assembly 2 to blow out the cylindrical film blank composed of ethylene-vinyl alcohol copolymer, adhesive resin and a small amount of food-grade antistatic masterbatch modified polyethylene, wherein the ethylene-vinyl alcohol copolymer is used to provide the inner liner bag with gas barrier properties, and the modified polyethylene with a small amount of food-grade antistatic masterbatch is used to provide the inner liner bag with antistatic properties, then the cylindrical film blank passes through the limiting ring 6 and the three-legged electric field removal frame 5 in turn, wherein the limiting ring 6 is in contact with the cylindrical film blank to accelerate its heat dissipation and limit the blank shape to avoid excessive expansion of the blank, then the cylindrical film blank gradually becomes a sheet shape after being extruded by the three-legged electric field removal frame 5, and in this process, the three-legged electric field removal frame 5 is in contact with the ground 1 through the support 1 to realize grounding, and then the three-legged electric field removal frame 5 discharges the surface charge of the film blank, and the sheet-shaped film blank is further shaped into a sheet shape by the guidance of the transmission roller 8 and the transmission roller 9, at this time the grounding assembly 7 is started to drive the film blank to move, at the same time the grounding assembly 7 is in contact with the ground 1 through the support 2 and the support 1 to realize grounding, and then the grounding assembly 7 further discharges the residual charge on the surface of the film blank, and then the film blank is pulled to the winding machine 20 by the guide assembly 10 for shaping and storage, thereby the inner liner bag with high gas barrier and no static charge is obtained.

[0040] Referring to the accompanying drawings Figure 2 The extrusion assembly 2 comprises a co-extrusion die 201, the upper side of the ground 1 is fixedly connected with the co-extrusion die 201, the inside of the co-extrusion die 201 is fixedly connected with a blow die head 202, the upper side of the ground 1 is fixedly connected with a spiral feeder 203, and the outside of the spiral feeder 203 is connected with the outside of the co-extrusion die 201.

[0041] Specifically, by putting the modified polyethylene with a small amount of food-grade antistatic masterbatch, the adhesive material and the ethylene-vinyl alcohol copolymer into different spiral feeders 203 respectively, and then the co-extrusion die 201 extrudes the above-mentioned raw materials, and the blow die head 202 blows the extruded raw materials into a cylindrical film blank, wherein the co-extrusion die 201, the blow die head 202 and the spiral feeder 203 are prior art and will not be described in detail here.

[0042] Referring to the accompanying drawings Figure 4 The grounding assembly 7 comprises a drive motor 701, the side wall of the support 2 is fixedly connected with the drive motor 701, the output end of the drive motor 701 is connected with a rotating column 702, and the outside of the rotating column 702 is fixedly connected with a contact block 703.

[0043] Specifically, by starting the drive motor 701 to drive the rotating column 702 to rotate in the inside of the support 2, and then the contact block 703 rotates synchronously under the drive of the rotating column 702, at this time the rotating column 702 is in contact with the film blank and guides the residual static charge of the film blank to the ground.

[0044] Referring to the drawings Figure 4 and the drawings Figure 5 , the guide assembly 10 comprises a guide roller one 1001, the outer part of which is rotatably connected to the inner part of the support two 4, and the inner part of the support one 3 is rotatably connected with a guide roller two 1002 and a guide roller three 1003.

[0045] Specifically, since the guide roller one 1001, the guide roller two 1002 and the guide roller three 1003 are arranged in sequence from top to bottom, the film blank is wound along the installation direction of the guide roller one 1001, the guide roller two 1002 and the guide roller three 1003 by the winding machine 20, the transmission roller three 13 and the contact block 703.

[0046] Referring to the drawings Figure 1 , the drawings Figure 6 and the drawings Figure 7 , the upper side of the ground 1 is fixedly connected with a fixed block one 11, the outer part of which is fixedly connected with a driving motor two 12, the output end of which is connected with a transmission roller three 13, the outer part of which is rotatably connected to the inner part of the fixed block one 11; the upper surface of the ground 1 is fixedly connected with a fixed block two 14, the side wall of which is fixedly connected with a storage tank 15, the inner part of which is provided with a spray head 16, the inner part of the storage tank 15 is rotatably connected with a rotating rod 18, the outer part of which is fixedly connected with a stirring block 19, the side wall of the rotating rod 18 is provided with a conveyor belt 17, and the side wall of the conveyor belt 17 is arranged outside the transmission roller three 13.

[0047] Specifically, by starting the driving motor two 12 to drive the transmission roller three 13 to rotate in the inner part of the fixed block one 11, at this time the mold blank is further extruded and transported to the winding machine 20 under the driving of the transmission roller three 13, in this process the transmission roller three 13 drives the rotating rod 18 to rotate along the inner part of the storage tank 15 through the conveyor belt 17, at the same time since the stirring block 19 is connected with the rotating rod 18, the stirring block 19 rotates under the driving of the rotating rod 18, and the stirring block 19 stirs the polyurethane-acrylic composite emulsion in the storage tank 15 uniformly, at this time the spray head 16 is started to spray the uniformly stirred composite emulsion on the surface of the mold blank as a coating, and the coating is further combined with the mold blank through the extrusion of the transmission roller three 13, so as to ensure that the composite emulsion is sprayed uniformly, and a dense coating is formed on the surface of the inner liner bag, further enhancing the high barrier property and antistatic effect of the inner liner bag.

[0048] Referring to the drawings Figure 5 , the three-legged electric field removing frame 5 and the limiting ring 6 are made of copper-aluminum alloy.

[0049] Specifically, the copper-aluminum alloy has good conductivity and durability, which enables the three-legged electric field removing frame 5 and the limiting ring 6 to be used for a long time and to preliminarily remove static electricity from the mold blank.

[0050] Referring to the drawings Figure 4 The rotating column 702 and the contact block 703 are made of stainless steel.

[0051] Specifically, the stainless steel has good electrical conductivity and weather resistance, which prolongs the service life of the rotating column 702 and the contact block 703 and enables the static charge to be removed again.

[0052] Referring to the drawings Figures 1-8 A production process of a high-barrier inner liner bag production device includes the following steps:

[0053] S1, raw material preparation and co-extrusion: the high molecular raw material is transported to the co-extrusion die 201 through the screw feeder 203, and is extruded into a cylindrical film blank through the blow die head 202;

[0054] S2, cooling and shaping: the cylindrical film blank is preliminarily shaped by air cooling to form a stable film tube;

[0055] S3, static elimination and guidance: the film tube is guided in the transmission direction by the transmission roller one 8 and the transmission roller two 9 after the static electricity is eliminated by the three-legged electric eliminator 5 and preliminarily positioned by the limiting ring 6;

[0056] S4, grounding treatment: the rotating column 702 and the contact block (703) are rotated by the driving motor one 701 in the grounding assembly 7 to continuously contact the film surface and further discharge the residual static electricity;

[0057] S5, surface treatment and winding: the film material is tensioned and transmitted to the transmission roller three 13 by the guide roller one 1001, the guide roller two 1002 and the guide roller three 1003, then the surface treatment agent is sprayed by the spray head (16), and finally wound into a roll by the winding machine 20.

[0058] In step S5, when the surface treatment agent is sprayed, the stirring block 19 in the storage box 15 is driven by the rotating rod 18 to continuously uniformly stir the surface treatment agent; wherein the surface treatment agent is a polyurethane-acrylic composite emulsion.

[0059] Specifically, the transmission roller three 13 is driven to rotate by the driving motor two 12, and the film material is smoothly pulled through the lower part of the spray head 16; at the same time, the transmission roller three 13 drives the rotating rod 18 and the stirring block 19 in the storage box 15 to continuously stir by the transmission belt 17, so as to ensure that the polyurethane-acrylic composite emulsion is uniform and has no precipitation; then the emulsion is uniformly sprayed on the film surface by the spray head 16, and the coating is tightly combined with the film material by the extrusion of the transmission roller three 13, forming a dense functional layer, so as to improve the gas barrier property, surface uniformity and antistatic property of the inner liner bag, and ensure the consistency of the quality of the wound product.

[0060] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be effected without departing from the spirit and scope of the present application, which is not limited to the exact construction and arrangement described. It is intended, therefore, to cover all modifications and adaptions that fall within the scope of the claims and their equivalents.

Claims

1. A high-barrier inner liner bag production apparatus, characterized in that, The system includes a ground (1), an extrusion assembly (2) is provided on the upper side of the ground (1), a bracket (3) is fixedly connected to the upper surface of the ground (1), a bracket (4) is fixedly connected to the upper side of the bracket (3), a tripod electric elimination frame (5) is fixedly connected inside the bracket (3), a limit ring (6) is fixedly connected inside the bracket (3), a grounding assembly (7) is provided on the side wall of the bracket (4), a transmission roller (8) and a transmission roller (9) are rotatably connected inside the bracket (4), a guide assembly (10) is provided on the outside of the bracket (4), and a winding machine (20) is fixedly connected to the upper side of the ground (1).

2. The high-barrier inner liner bag production apparatus according to claim 1, characterized in that, The extrusion assembly (2) includes a co-extrusion die (201), which is fixedly connected to the upper side of the ground (1). A blow die head (202) is fixedly connected inside the co-extrusion die (201), and a screw feeder (203) is fixedly connected to the upper side of the ground (1). The outside of the screw feeder (203) is connected to the outside of the co-extrusion die (201).

3. The high-barrier inner liner bag production apparatus according to claim 1, characterized in that, The grounding assembly (7) includes a drive motor (701), the side wall of the bracket (4) is fixedly connected to the drive motor (701), the output end of the drive motor (701) is connected to a rotating column (702), and the outside of the rotating column (702) is fixedly connected to a contact block (703).

4. The high-barrier inner liner bag production apparatus according to claim 1, characterized in that, The guide assembly (10) includes a guide roller one (1001), the outside of which is rotatably connected to the inside of the bracket two (4), and the inside of the bracket one (3) is rotatably connected to guide roller two (1002) and guide roller three (1003).

5. The high-barrier inner liner bag production apparatus according to claim 1, characterized in that, A fixed block (11) is fixedly connected to the upper side of the ground (1). A drive motor (12) is fixedly connected to the outside of the fixed block (11). A transmission roller (13) is connected to the output end of the drive motor (12). The transmission roller (13) is rotatably connected to the inside of the fixed block (11).

6. The high-barrier inner liner bag production apparatus according to claim 1, characterized in that, A fixing block two (14) is fixedly connected to the upper surface of the ground (1). A storage box (15) is fixedly connected to the side wall of the fixing block two (14). A nozzle (16) is provided inside the storage box (15). A rotating rod (18) is rotatably connected inside the storage box (15). A stirring block (19) is fixedly connected to the outside of the rotating rod (18). A conveyor belt (17) is provided on the side wall of the rotating rod (18). The side wall of the conveyor belt (17) is located outside the transmission roller three (13).

7. The high-barrier inner liner bag production apparatus according to claim 1, characterized in that, The tripod electric discharger (5) and the limiting ring (6) are both made of copper-aluminum alloy.

8. The high-barrier inner liner bag production apparatus according to claim 3, characterized in that, Both the rotating column (702) and the contact block (703) are made of stainless steel.

9. A production process for a high-barrier inner liner bag production device, characterized in that, An apparatus for producing a high-barrier inner liner bag according to any one of claims 1-8, comprising the following steps: S1. Raw material preparation and co-extrusion: The polymer raw material is conveyed to the co-extrusion die (201) by the screw feeder (203) and extruded through the blown die head (202) to form a cylindrical film preform; S2. Cooling and Shaping: The cylindrical preform is initially shaped by air cooling to form a stable membrane tube; S3. Static electricity elimination and guidance: The membrane tube is static electricity eliminated by the tripod (5) and initially positioned by the limiting ring (6). Then, the transmission direction is guided by the first transmission roller (8) and the second transmission roller (9). S4. Grounding treatment: The rotating column (702) and the contact block (703) are driven to rotate by the drive motor (701) in the grounding component (7) and continue to contact the membrane surface to further discharge residual static electricity; S5. Surface treatment and winding: The film material is tensioned and transmitted to the transmission roller 3 (13) by the guide roller 1 (1001), guide roller 2 (1002) and guide roller 3 (1003), then the surface treatment agent is sprayed by the nozzle (16), and finally the film is wound into a roll by the winding machine (20).

10. The production process of a high-barrier inner liner bag production device according to claim 9, characterized in that, In step S5, when the surface treatment agent is sprayed, the stirring block (19) in the storage tank (15) is driven by the rotating rod (18) to continuously and uniformly stir the surface treatment agent; wherein the surface treatment agent is a polyurethane-acrylic composite emulsion.

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