Patent Publication Number: US-2023149971-A1

Title: Gravure Coater Test Apparatus and Gravure Coater

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a national phase entry under 35 U.S.C. § 371 of International Application No. PCT/KR2021/004255, filed on Apr. 6, 2021, which claims priority to Korean Patent Application No. 10-2020-0042334, filed on Apr. 7, 2020, the disclosures of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a gravure coater test apparatus and a gravure coater. More particularly, to a gravure coater test apparatus for allowing various phenomena (e.g., oozing phenomenon and coating phenomenon) to be confirmed with respect to the gravure coater and a gravure coater to which test results are applied 
     BACKGROUND ART 
     According to an example, the gravure coater includes a pressure-sensitive adhesive tray which accommodates a pressure-sensitive adhesive that is a coating material, a gravure roll which is partially submerged in the pressure-sensitive adhesive tray (latex tray) and is rotated in a state that pattern grooves formed on the surface of the gravure roll is filled with the pressure-sensitive adhesive, and a backup roll which is circumscribed on the gravure roll and is rotated. 
     When a coating film is advanced between the gravure roll and the backup roll while the gravure roll and backup roll that are circumscribed are being rotated relatively to each other, the pressure-sensitive adhesive filled in the pattern grooves is transferred to one surface of the coating film. 
     At this time, a doctor blade is provided on one side of the gravure roll to scrape the pressure-sensitive adhesive adhered to the surface of the gravure roll except for the pressure-sensitive adhesive filled in the pattern grooves. Therefore, the pressure-sensitive adhesive filled in the pattern grooves may be coated on the coating film to a set coating amount and required coatability. 
     The gravure coater is high-speed coating equipment, and oozing phenomenon may occur in which a pressure-sensitive adhesive or water-based pressure-sensitive adhesive flows from the surface of the gravure roll to the side edge thereof depending on the rotational speed of the gravure roll when the gravure coater is driven at a high speed. Therefore, the coating thickness (coating amount and coatability) of the pressure-sensitive adhesive or the water-based pressure-sensitive adhesive coated on the coating film becomes non-uniform, and contraction phenomenon of the coating film may occur at both sides in the width direction. 
     However, it has been possible to test the coating phenomenon only in a gravure coater mass-producing products in the field in a state that there is not a method capable of verifying such problems. Therefore, it has realistically been difficult to perform various tests for the gravure coater (e.g., oozing phenomenon due to the relationship between the doctor blade and the water-based pressure-sensitive adhesive, and coating phenomenon for the coating amount and coatability of the water-based pressure-sensitive adhesive). 
     DISCLOSURE 
     Technical Problem 
     An aspect of the present technology is to provide a gravure coater test apparatus capable of testing various phenomena (e.g., oozing phenomenon and coating phenomenon) with respect to the gravure coater. Further, other aspect of the present technology is to provide a gravure coater applied after completing a test with the gravure coater test apparatus. 
     Technical Solution 
     A gravure coater test apparatus according to an embodiment of the present invention includes a gravure roll and a backup roll which are circumscribed to each other, a motor which drives the gravure roll partially submerged in a water-based pressure-sensitive adhesive for coating, a controller which adjusts the rotational speed of the motor, a doctor blade which is selected from a plurality of types to scrape the water-based pressure-sensitive adhesive from the surface of the gravure roll being rotated, and an infrared analyzer which allows at least one of the type of the water-based pressure-sensitive adhesive corresponding to the selected doctor blade, the uniformity of the coating surface, and the amount of the coated water-based pressure-sensitive adhesive to be confirmed. 
     The doctor blade may include a tip part forming a curved surface toward the rotation direction of the gravure roll. 
     An extension line of the lower surface of the tip part in the doctor blade and a circumscribed line of the gravure roll may form an intersection angle of 60 to 120°. 
     The water-based pressure-sensitive adhesive may have a viscosity of 50 to 70 cPs (centipoise, g/cm s). 
     A gravure coater test apparatus according to an embodiment of the present invention may further include a viscometer for measuring the viscosity of the water-based pressure-sensitive adhesive, and a moisture meter for measuring the solid content of the water-based pressure-sensitive adhesive 
     A gravure coater according to an embodiment of the present invention includes a gravure roll and a backup roll which are circumscribed to each other, a motor which drives the gravure roll partially submerged in a water-based pressure-sensitive adhesive for coating, and a doctor blade which is selected from a plurality of types to scrape the water-based pressure-sensitive adhesive from the surface of the rotating gravure roll so that the water-based pressure-sensitive adhesive filled in the grooves of the gravure roll is gravure printed on a coating film advancing between the gravure roll and the backup roll. 
     Advantageous Effects 
     Since the gravure coater test apparatus of an embodiment controls the rotational speed of the gravure roll by adjusting the rotational speed of the motor driving the gravure roll with the controller, and can confirm at least one of the type of the coated water-based pressure-sensitive adhesive, the uniformity of the coating surface, and the amount of the coated water-based pressure-sensitive adhesive through the infrared analyzer, it enables an appropriate doctor blade to be selected from a plurality of types of doctor blades so as to correspond to the water-based pressure-sensitive adhesive. 
     Therefore, the gravure coater test apparatus of an embodiment can test and confirm various phenomena such as oozing phenomenon, coating phenomenon, etc. occurring when coating the water-based pressure-sensitive adhesive while changing the doctor blade and the water-based pressure-sensitive adhesive with respect to the gravure coater. 
     Further, the gravure coater of an embodiment may be used by applying the relationship between the test-completed doctor blade and the water-based pressure-sensitive adhesive to actual mass production after completing the test of a doctor blade through the gravure coater test apparatus. At this time, the gravure coater can be used in the production site after being manufactured larger at an appropriate ratio for mass production by applying the ratio relationship between test and mass production. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a block diagram of a gravure coater testing apparatus according to an embodiment of the present invention. 
         FIG.  2    is a perspective view illustrating a gravure coater test apparatus according to an embodiment of the present invention and a gravure coater. 
         FIG.  3    is a side view of  FIG.  2   . 
         FIG.  4    is a partially enlarged view illustrating an enlarged part of a state in which the doctor blade comes in contact with the gravure roll. 
     
    
    
     MODE FOR INVENTION 
     Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that a person with ordinary skill in the art to which the present invention pertains can easily implement them. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the scope of the present invention. The drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification. 
       FIG.  1    is a block diagram of a gravure coater test apparatus according to an embodiment of the present invention. Referring to  FIG.  1   , the gravure coater test apparatus according to an embodiment includes a gravure coater  1 , a controller  2 , and an infrared analyzer  3 . Furthermore, the gravure coater test apparatus may further include a viscometer  4  and a moisture meter  5 . 
       FIG.  2    is a perspective view illustrating a gravure coater test apparatus according to an embodiment of the present invention and a gravure coater. Referring to  FIGS.  1  and  2   , the gravure coater  1  according to an embodiment includes a gravure roll  11 , a backup roll  12 , a motor  13 , and a doctor blade  15 . 
     The gravure roll  11  and the backup roll  12  are circumscribed to each other and rotationally driven, and allow coating to be performed on one side of the coating film  16  while advancing the coating film  16  through therebetween. The gravure roll  11  is provided with pattern grooves (not shown) on the surface thereof so that a coating material CM (hereinafter, referred to as an example “water-based pressure-sensitive adhesive”) filled in the pattern grooves is transferred to the surface of the coating film  16 . 
     The motor  13  is installed on a drive shaft  111  of the gravure roll  11  to perform a rotational motion of the gravure roll  11 . According to the rotation of the gravure roll  11 , the backup roll  12  is circumscribed with the gravure roll  11  to advance the coating film  16  while it is being rotated in the reverse direction to the rotation of the gravure roll  11 . Although not shown, the motor may be installed at the backup roll to enable the gravure roll to be rotated by rotating the backup roll. 
     The gravure roll  11  is rotated by the motor  13  in a state that it is partially submerged in the water-based pressure-sensitive adhesive CM for coating. The water-based pressure-sensitive adhesive CM is accommodated in the pressure-sensitive adhesive tray  17 , and the gravure roll  11  is installed inside the pressure-sensitive adhesive tray  17  so that the gravure roll  11  enables its surface to be coated up with the water-based pressure-sensitive adhesive CM while being rotated. 
     As an example, the water-based pressure-sensitive adhesive CM may have a viscosity of 50 to 70 cPs (centipoise, g/cm s). When the viscosity is less than 50 cPs, the water-based pressure-sensitive adhesive CM is not sufficiently coated up on the gravure roll  11 , but is flown down. When the viscosity is more than 70 cPs, the water-based pressure-sensitive adhesive CM may not be sufficiently transferred to the gravure roll  11  by the coating film  16 . 
     Further, the water-based pressure-sensitive adhesive CM may be formed by adjusting the load level of latex by the rotational speed (rpm) of the gravure roll  11 . That is, the water-based pressure-sensitive adhesive CM may be formed with latex being contained in order to provide stickiness. 
     For example, a first water-based pressure-sensitive adhesive CM 1  has a viscosity of 50 to 70 cPs when measured using a viscometer  4  ( 62  meshes, 30 rpm), and it has a solid content of TSC 53 to 55% when measured using a moisture meter  5  (TSC). 
     For another example, a second water-based pressure-sensitive adhesive CM 2  has a viscosity of 100 cPs when measured using a viscometer  4  ( 62  meshes, 30 rpm), and it has a solid content of TSC 54% when measured using a moisture meter  5  (TSC). 
     The doctor blade  15  may be used after being selected from a plurality of types to scrape the water-based pressure-sensitive adhesive CM from the surface of the rotating gravure roll  11 . In the gravure coater test apparatus, a plurality of doctor blades  15  are provided, and may be selectively used depending on the type of the water-based pressure-sensitive adhesive CM and the coating phenomenon (i.e., the uniformity of the coating surface and the amount of the coated water-based pressure-sensitive adhesive). 
       FIG.  3    is a side view of  FIG.  2   . Referring to  FIGS.  1  to  3   , the controller  14  in the gravure coater test apparatus controls the rotational speed of the gravure roll  11  to implement a required coating speed with respect to the coating film  16 . 
     The controller  14  controls driving of the motor  13  in order to select the doctor blade  115  corresponding to the water-based pressure-sensitive adhesive CM. Therefore, although the controller  14  does not mean a controller (not shown) controlling the motor  13  in the gravure coater, it may also be used in common. 
     In the gravure coater test apparatus, the infrared analyzer  3  enables the type of the water-based pressure-sensitive adhesive CM corresponding to the doctor blade  15  selected from the plurality of doctor blades  15 , and the coating phenomenon (i.e., the uniformity of the coating surface and the amount of the coated water-based pressure-sensitive adhesive) to be confirmed. 
     As an example, the infrared analyzer  3  enables the coating surface to be analyzed by irradiating infrared rays toward the coating film  16  that has passed through the surface of the gravure roll  11  and receiving a signal that is returned after being reflected from the coating surface of the coating film  16 . 
     As a result of checking the received signal of the infrared analyzer  3  in the controller  14 , that is, the relationship between the doctor blade  15 , and the type of the water-based pressure-sensitive adhesive CM and the coating phenomenon (i.e., the uniformity of the coating surface and the amount of the coated water-based pressure-sensitive adhesive) is confirmed to enable the doctor blade  15  corresponding to the water-based pressure-sensitive adhesive CM to be selected from the plurality of doctor blades  15 . 
     In the test-completed gravure coater, a plurality of doctor blades  15  are provided, and may be actually selected and used depending on the type of the water-based pressure-sensitive adhesive CM to be used and the coating phenomenon (i.e., the uniformity of the coating surface and the amount of the coated water-based pressure-sensitive adhesive CM). 
     Further, the gravure coater test apparatus according to an embodiment may further include a viscometer  4  or a moisture meter  5 . The viscometer  4  may measure the viscosity of a water-based pressure-sensitive adhesive CM used. The moisture meter  5  may measure the solid content in the water-based pressure-sensitive adhesive CM. That is, the solid content is for confirming the solid content finally remaining in the coating film  16  in a state that the solid content is dried after coating a solid content on the coating film  16 . 
       FIG.  4    is a partially enlarged view illustrating an enlarged part of a state in which the doctor blade comes in contact with the gravure roll. Referring to  FIGS.  2  to  4   , the doctor blade  15  has an intersection angle θ. 
     The intersection angle θ is formed by the intersection of an extension line L 1  of the lower surface of the tip part having a curved surface facing the rotation direction of the gravure roll  11  in the doctor blade  15  and a circumscribed line L 2  of the gravure roll  11 . The intersection angle θ may form 60 to 120°. 
     The intersection angle (θ) makes it possible to suppress a phenomenon that the water-based pressure-sensitive adhesive CM coated on the surface of the gravure roll  11  goes over the top of the doctor blade  15  and remains by high-speed rotation of the gravure roll in the process of scraping the water-based pressure-sensitive adhesive CM on the surface of the gravure roll  11  by the doctor blade  15 . That is, the intersection angle θ suppresses the phenomenon that the water-based pressure-sensitive adhesive CM coated on a portion except for the pattern grooves is less scraped and goes over the top of the doctor blade  15  and remains on the surface of the gravure roll  11 . 
     When the intersection angle θ is less than 60°, the doctor blade  15  cannot pressurize the surface of the gravure roll  11  and is excessively flexibly contacted therewith so that the doctor blade  15  may not be able to scrape the water-based pressure-sensitive adhesive CM on the surface of the gravure roll  11  with sufficient force. In this case, the water-based pressure-sensitive adhesive CM is less scraped and may go over the top of the doctor blade  15  and remain on the surface of the gravure roll  11 . 
     When the intersection angle θ is more than 120°, the doctor blade  15  may not be able to make sufficient contact with the surface of the gravure roll  11  due to the tendency of the doctor blade  15  to lift from the surface of the gravure roll  11  and the water-based pressure-sensitive adhesive CM. Even in this case, the water-based pressure-sensitive adhesive CM may go over the top of the doctor blade  15  without being scraped by the doctor blade  15  and may remain on the surface of the gravure roll  11 . 
     The intersection angle θ may be adjusted within the range of 60 to 120° by the diameter or rotational speed of the gravure roll  11  and the viscosity of the water-based pressure-sensitive adhesive CM. That is, the intersection angle θ is adjusted within the range in which the doctor blade  15  can effectively scrape a water-based pressure-sensitive adhesive CM having a viscosity by appropriately pressurizing the surface of the gravure roll  11 , and it may also be adjusted depending on the material of the doctor blade  15  and the viscosity of the water-based pressure-sensitive adhesive CM. 
     As an example, the doctor blade  15  includes a tip part  151  which forms a curved surface forming the intersection angle θ with the gravure roll  11  and a plate-shaped installation part  152  which is connected to the tip part  151  and formed long in the longitudinal direction of the gravure roll  11 . 
     The doctor blade  15  is disposed in a region A 1  which is formed to the lower side where a horizontal line passing through the center of the gravure roll  11  and a vertical line intersect. Accordingly, the tip part  151  of the curved surface comes into contact with the gravure roll  11  at an intersection angle θ, and the installation part  152  is disposed within the region A 1  which is formed to the lower side where the horizontal line and the vertical line intersect. Further, the region A 1  and the doctor blade  15  disposed in the region A 1  do not require an additional space required for the installation of the gravure coater  1  while implementing the effects of the present technology. 
     The gravure coater test apparatus is designed to be small to enable laboratory-level testing and controls the motor  13  through the controller  2 , thereby enabling the rotational speed of the gravure roll  11  connected to the motor  13  to be easily adjusted. 
     Since the gravure coater test apparatus enables the doctor blade  15  to be easily changed, it may enable the structure of the doctor blade  15  to be applied to a water-based pressure-sensitive adhesive CM for each type of latex. In addition, the gravure coater test apparatus makes it possible to easily confirm the coating phenomenon, i.e., coatability according to the coating amount by using the infrared analyzer  3 . That is, the gravure coater test apparatus enables the coating phenomenon to be easily analyzed and confirmed. 
     The gravure coater  1  applied to the gravure coater test apparatus is reduced and configured to ⅓ the size of an actual gravure coater applied to mass production. For example, when the diameter of the gravure roll is formed to be 60 cm in the mass production facility, the diameter of the gravure roll  11  in the present embodiment may be formed to be 20 cm. 
     At this time, the coating speed can be implemented three times in line with the mass production site. For example, when the coating speed in the mass production site is 160 rpm, the coating speed of the embodiment may be 480 rpm, which is three times that. The controller  14  according to an embodiment may control the rotational speed of the gravure roll  11  to 0 to 900 rpm through the motor  13 . 
     Meanwhile, after the gravure coater  1  according to an embodiment completes a test of the doctor blade  15  through the gravure coater test apparatus, the relationship between the test-completed doctor blade  15  and the water-based pressure-sensitive adhesive CM may be applied to and used in the actual mass production. At this time, the gravure coater  1  may be used in the production site after being manufactured larger at a ratio suitable for mass production by applying the ratio relationship between the test and mass production. 
     The gravure coater  1  in which the doctor blade  15  according to an embodiment was installed to an intersection angle θ of 120° ° on the gravure roll  11  and the case where the doctor blade of Comparative Example had intersection angles of 30° and 120° were compared. First and second water-based pressure-sensitive adhesives CM 1  and CM 2  were used. 
     At this time, a small amount of the oozing phenomenon occurred in Comparative Example where the gravure roll had a coating speed, i.e., a rotational speed of 400 rpm and a coating amount of 17 μm. In contrast, the oozing phenomenon did not occur in Example where the gravure roll  11  had a rotational speed of 400 rpm and a coating amount of 17 μm. 
     Table 
     Referring to Table 1, oozing phenomena were compared in unit areas (cm2) where the first and second water-based pressure-sensitive adhesives CM 1  and CM 2  were coated to a coating amount of 17 μm at rotational speeds of the gravure roll  11  of 300, 400, 500, and 600 rpm. 
     
       
         
           
               
               
             
               
                   
                 TABLE 1 
               
             
            
               
                   
                   
               
               
                   
                 Coating 
               
            
           
           
               
               
               
               
            
               
                   
                 Doctor 
                 Oozing area (cm 2 ) by 
                 phenomenon 
               
               
                   
                 blade 
                 rotational speed (rpm) 
                 Coatability/coating 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 blade 
                 300 
                 400 
                 500 
                 600 
                 amount 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 First water-base 
                 Comparative 
                 0 
                 10 
                 30 
                 60 
                 uniform/17 μm 
               
               
                 pressure-sensitive 
                 Example 
               
               
                 adhesive 
                 Example 
                 0 
                 0 
                 10 
                 20 
                 uniform/17 μm 
               
               
                 Second water-base 
                 Comparative 
                 0 
                 15 
                 40 
                 60 
                 uniform/17 μm 
               
               
                 pressure-sensitive 
                 Example 
               
               
                 adhesive 
                 Example 
                 0 
                 0 
                 10 
                 20 
                 uniform/17 μm 
               
               
                   
               
            
           
         
       
     
     The first and second water-based pressure-sensitive adhesives CM 1  and CM 2  were used, and the rotation speed of the gravure roll  11  was changed to 300, 400, 500, and 600 rpm so that the first and second water-based pressure-sensitive adhesives CM 1  and CM 2  were coated to a coating amount of 17 μm on the coating film  16 . 
     As a whole, the coating phenomenon, that is, the coatability with respect to the coating amount, appeared uniformly. Compared to Comparative Example, the oozing phenomenon was less occurred in Example when coating at 400, 500, and 600 rpm. Therefore, Example can effectively prevent the oozing phenomenon. 
     It can be seen in Comparative Example compared to Example that the first and second water-based pressure-sensitive adhesives CM 1  and CM 2  coated on the gravure roll  11  are flown down further to the side of the gravure roll  11  as the physical bonding of latex within the first and second water-based pressure-sensitive adhesives CM 1  and CM 2  is lowered due to high-speed rotation of the gravure roll  11 . 
     Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto, the preferred embodiments can be implemented in various modified forms within the scope of the claims, the description of the invention, and the accompanying drawings, and it goes without saying that these various modified forms also fall within the scope of the present invention. 
     
       
         
           
               
             
               
                   
               
               
                 (Explanation of marks) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 1: Gravure coater 
                 2: Controller 
               
               
                 3: Infrared analyzer 
                 4: Viscometer 
               
               
                 5: Moisture meter 
                 11: Gravure roll 
               
               
                 12: Backup roll 
                 13: Motor 
               
               
                 15: Doctor blade 
                 16: Coating film 
               
               
                 17: Pressure-sensitive adhesive tray 
                 111: Drive shaft 
               
               
                 151: Tip part 
                 152: Installation part 
               
               
                 A1: Region 
               
            
           
           
               
            
               
                 CM: Coating material (water-based pressure-sensitive adhesive) 
               
               
                 CM1, CM2: First and second water-based pressure-sensitive adhesives 
               
            
           
           
               
               
            
               
                 L1: Extension line 
                   
               
               
                 L2: Circumscribed line 
                 θ: Intersection angle