Abstract:
There are provided a vacuum chamber system of a coating apparatus and a coating method using the same that prevents the attraction phenomenon of a coating solution in intermittent coating, so that the failure rate of coating is reduced, thereby improving the quality of products. In one embodiment, a vacuum chamber system of a coating apparatus includes a vacuum chamber connected to a coating solution outlet of the coating apparatus. A sound pressure generating unit is connected to one region of the vacuum chamber to generate sound pressure. A buffer tank is provided between the vacuum chamber and the sound pressure generating unit. In the vacuum chamber system, a control unit is further provided between the vacuum chamber and the buffer tank. The control unit controls air to be selectively inhaled or blocked from the vacuum chamber and the sound pressure generating unit.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority to and the benefit of Korean Patent Application No. 10-2010-0074957, filed on Aug. 3, 2010, in the Korean Intellectual Property Office, the entire content of which is incorporated herein by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    An aspect of the present invention relates to a vacuum chamber system of a coating apparatus and a coating method using the same, and more particularly, to a vacuum chamber system of a coating apparatus and a coating method using the same that can improve the quality of products. 
         [0004]    2. Description of the Related Art 
         [0005]    In general, a coating apparatus includes a coating solution inlet and a coating solution outlet. If a coating solution is supplied to the coating solution inlet of the coating apparatus, it is sprayed through the coating solution outlet along a coating solution flow path. In this instance, coating is performed while a base material is transferred in one direction at the side of the coating solution outlet. 
         [0006]    When thin-film coating or high-speed coating is performed in the coating of the base material, a coating bead of the coating solution is pushed from an upstream side to a downstream side in the direction in which the coating is performed with respect to the base material. Therefore, the shape of the coating bead is modified, and accordingly, the coating may not be performed. 
       SUMMARY 
       [0007]    In one embodiment, there are provided a vacuum chamber system of a coating apparatus and a coating method using the same that includes a control unit for controlling air to be selectively inhaled into a vacuum chamber attached to the coating apparatus and a buffer tank, thereby preventing the attraction phenomenon of a coating solution in intermittent coating. 
         [0008]    According to an aspect of the present invention, there is provided a vacuum chamber system of a coating apparatus, the system including: a vacuum chamber connected to a coating solution outlet of the coating apparatus; a sound pressure generating unit connected to one region of the vacuum chamber to generate sound pressure; and a buffer tank provided between the vacuum chamber and the sound pressure generating unit, wherein a control unit is further provided between the vacuum chamber and the buffer tank, and the control unit controls air to be selectively inhaled into or blocked from the vacuum chamber and the sound pressure generating unit. 
         [0009]    The control unit may be formed with first and second control units that control the air to be independently inhaled into or blocked from the vacuum chamber and the sound pressure generating unit. 
         [0010]    The control unit may be formed as a 3-way switching valve. 
         [0011]    The 3-way switching valve may be operated automatically or manually. 
         [0012]    The buffer tank may temporarily absorb the pressure sound generated from the sound pressure generating unit in the operation of the control unit. 
         [0013]    The sound pressure generating unit may be formed as a fan. 
         [0014]    An intermittent unit for opening/closing the coating solution outlet may be further formed at the coating solution outlet. 
         [0015]    The coating apparatus may be used when an active material slurry is coated on a metal base material of a secondary battery. 
         [0016]    According to an aspect of the present invention, there is provided an intermittent coating method using the vacuum chamber system of the coating apparatus, the method including: forming a coating portion by controlling the first and second control units in the state that the air is blocked from the vacuum chamber and the sound pressure generating unit so that sound pressure is operated to the vacuum chamber; and forming a non-coating portion by controlling the first and second control units in the state that the air is independently inhaled to the vacuum chamber and the sound pressure generating unit. 
         [0017]    In the forming of the coating portion, the first control unit may control the vacuum chamber and the sound pressure generating unit to be connected to each other. 
         [0018]    In the forming of the coating portion, the second control unit may control the vacuum chamber and the sound pressure generating unit to be connected to each other. 
         [0019]    In the forming of the non-coating portion, the first control unit may control the air to be inhaled to the vacuum chamber while blocking the vacuum chamber and the sound pressure generating unit. 
         [0020]    In the forming of the non-coating portion, the second control unit may control the air to be inhaled to the sound pressure generating unit while blocking the vacuum chamber and the sound pressure generating unit. 
         [0021]    As described above, according to embodiments of the present invention, the attraction phenomenon of a coating solution is prevented in intermittent coating, so that the failure rate of coating can be reduced, thereby improving the quality of products. Also, the intermittent coating is smoothly performed, thereby enhancing productivity. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    The accompanying drawings, together with the specification, illustrate exemplary embodiments of the present invention, and, together with the description, serve to explain the principles of the present invention. 
           [0023]      FIG. 1  is a schematic process view showing a process of preparing a coating material using a coating apparatus having a vacuum chamber system attached thereto according to an embodiment of the present invention. 
           [0024]      FIG. 2A  is a sectional view showing a state that the shape of a coating bead is modified in thin-film or high-speed coating. 
           [0025]      FIG. 2B  is a sectional view showing a state that sound pressure is generated in the coating bead using a vacuum chamber. 
           [0026]      FIG. 3  is a plan view showing a state that an attraction phenomenon occurs at an end of a coating portion, from which a non-coating portion is started. 
           [0027]      FIG. 4  is a sectional view showing a vacuum chamber system of a coating apparatus according to an embodiment of the present invention. 
           [0028]      FIG. 5  is a block diagram showing a state that air is not inhaled to the vacuum chamber system of the coating apparatus according to the embodiment of the present invention. 
           [0029]      FIG. 6  is a block diagram showing a state that air is inhaled to the vacuum chamber system of the coating apparatus according to the embodiment of the present invention. 
           [0030]      FIG. 7  is a plan view showing a state a material is coated using the vacuum chamber system of the coating apparatus according to the embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0031]    In the following detailed description, only certain exemplary embodiments of the present invention have been shown and described, simply by way of illustration. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not restrictive. In addition, when an element is referred to as being “on” another element, it can be directly on the another element or be indirectly on the another element with one or more intervening elements interposed therebetween. Also, when an element is referred to as being “connected to” another element, it can be directly connected to the another element or be indirectly connected to the another element with one or more intervening elements interposed therebetween. Hereinafter, like reference numerals refer to like elements. 
         [0032]    Hereinafter, a vacuum chamber system of a coating apparatus and a coating method using the same according to embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
         [0033]      FIG. 1  is a schematic process view showing a process of preparing a coating material using a coating apparatus having a vacuum chamber system attached thereto according to an embodiment of the present invention. 
         [0034]    Referring to  FIG. 1 , a base material  10  wound around rolls  20  at both sides thereof is mounted to be continuously transferred. A coating apparatus  30 , a drying apparatus  40  and a slitting apparatus  50  are sequentially mounted over the base material  10 . The coating apparatus  30  according to this embodiment may be used in various fields. However, a coating apparatus for coating an active material slurry on a metal base material of a secondary battery will be described in the following embodiments. 
         [0035]    First, a binder solution is made by mixing a binder with a solvent, and then an active material slurry is then prepared by mixing an active material and a conductive or additive agent in the binder solution. Subsequently, the active material slurry is coated on the base material  10  using the coating apparatus  30  and then dried using the drying apparatus  40 . After rolling is performed so as to increase the capacity density of the active material, slitting is performed using the slitting apparatus  50 , thereby obtaining a coating base material with a constant width. 
         [0036]    Here, the active material slurry refers to a state that it contains the solvent, and the active material refers to a state where the solvent is removed from the active material slurry by drying the active material slurry. 
         [0037]      FIG. 2A  is a sectional view showing a state that the shape of a coating bead is modified in thin-film or high-speed coating.  FIG. 2B  is a sectional view showing a state that sound pressure is generated in the coating bead using a vacuum chamber. 
         [0038]    Referring to  FIGS. 2A and 2B , thin-film or high-speed coating may be performed using body portions  30   a  and  30   b  (see  FIG. 4 ) of a coating apparatus such as a slot die. In this instance, a coating bead of a coating solution  100  sprayed through a coating solution outlet  32  formed between the body portions  30   a  and  30   b  of the coating apparatus is pushed from an upstream side to a downstream side in the direction in which the base material  10  is advanced. When the coating is performed using the body portions  30   a  and  30   b  of the coating apparatus, modifications  102  may occur in the shape of the coating bead. 
         [0039]    In order to prevent such a problem, a vacuum chamber  60  may be provided to pull the coating bead to the upstream side. Sound pressure is operated to the interior of the vacuum chamber  60  so that the coating bead is normally formed. A buffer tank  70  (see  FIG. 4 ) and a sound pressure generating unit  80  (see  FIG. 4 ) are further included in the vacuum chamber system so that the sound pressure is operated to the interior of the vacuum chamber  60 . Their detailed descriptions will be described later in  FIGS. 4 to 6 . 
         [0040]      FIG. 3  is a plan view showing a state that an attraction phenomenon occurs at an end of a coating portion, from which a non-coating portion is started. 
         [0041]    Referring to  FIG. 3 , in a case where continuous coating is performed using the coating apparatus having the vacuum chamber system of  FIG. 2B  attached thereto, it is smoothly performed by the operation of the sound pressure. However, in a case where intermittent coating is performed using the coating apparatus having the vacuum chamber system of  FIG. 2B  attached thereto, an attraction phenomenon  101  of the coating solution occurs as shown in  FIG. 3 . 
         [0042]    In a case where, the opening/closing of the coating solution outlet  32  is controlled using an intermittent valve for performing the intermittent coating, a coating portion  100   a  and a non-coating portion  100   b  are alternately formed on the base material  10 . Here, the non-coating portion  100   b  is a section in which the coating is not performed. That is, the coating portion  100   a  is intermittently formed. 
         [0043]    The reason why the attraction phenomenon  101  occurs is that the coating solution is attracted to the inside of the coating solution outlet  32  when the intermittent valve is closed. In this instance, the sound pressure operated in the vacuum chamber prevents the intermittent valve from attracting the coating solution. As a result, the attraction phenomenon occurs at every portion at which the intermittently coated coating portion  100   a  is finished. 
         [0044]      FIG. 4  is a sectional view showing a vacuum chamber system of a coating apparatus according to an embodiment of the present invention. 
         [0045]    Referring to  FIG. 4 , the vacuum chamber system of the coating apparatus according to this embodiment includes a vacuum chamber  60 , a buffer tank  70 , a sound pressure generating unit  80  and control units  90   a  and  90   b.    
         [0046]    The vacuum chamber  60  is connected to a coating solution outlet  32  of the coating apparatus  30 . The buffer tank  70  is connected to one region of the vacuum chamber  60  through a pipe or the like, and the sound pressure generating unit  80  is also connected to the buffer tank  70  through a pipe or the like. 
         [0047]    The coating apparatus  30  will be briefly described. The coating apparatus  30  includes a first body portion  30   a , a second body portion  30   b , a coating solution inlet  31  and a coating solution outlet  32 . The first and second body portions  30   a  and  30   b  are assembled with a certain gap interposed therebetween, and one side of the gap may be the coating solution outlet  32 . 
         [0048]    A coating solution supply unit (not shown) may be provided to the coating solution inlet  31 , and the coating solution inlet  31  may be extended to a coating solution flow path connected to the gap. A material  10  is transferred in a fixed direction by a roll  20  at the side of the coating solution outlet  32 , and coating is performed by a coating solution  100  sprayed from the coating solution outlet  32 . 
         [0049]    The sound pressure generating unit  80  is formed as a fan or the like, and generates sound pressure to supply the sound pressure to the vacuum chamber  60  via the buffer tank  70 . Here, the sound pressure refers to pressure lower than the air pressure, and the coating solution  100  sprayed through the coating solution outlet  32  connected to the vacuum chamber  60  is influenced by the sound pressure. 
         [0050]    The buffer tank  70  may temporarily absorb the sound pressure generated from the sound pressure generating unit  80  in the operation of the control units  90   a  and  90   b  which will be described below. That is, the buffer tank  70  may be a pressure or shock-absorbing tank that temporarily absorbs pressure generated in the operation of the control units  90   a  and  90   b . Accordingly, unstable sound pressure can be stabilized in the buffer tank  70  to supply the stabilized sound pressure to the vacuum chamber  60 . 
         [0051]    The control units  90   a  and  90   b  may be further provided between the vacuum chamber  60  and the buffer tank  70 . The control units  90   a  and  90   b  may be operated so that air is selectively inhaled or blocked from the vacuum chamber  60  and the sound pressure generating unit  80 . 
         [0052]    The control units may be formed with first and second control units  90   a  and  90   b  operated so that air is inhaled or blocked from the vacuum chamber  60  and the sound pressure generation unit  80 . The control units  90   a  and  90   b  may be formed as 3-way switching valves. In this instance, the 3-way switching valve may be operated manually or automatically. 
         [0053]      FIG. 5  is a block diagram showing a state where air is not inhaled into the vacuum chamber system of the coating apparatus according to the embodiment of the present invention. 
         [0054]    Referring to  FIG. 5 , in a case where coating is intermittently performed using the vacuum chamber system of the coating apparatus according to this embodiment, the sound pressure of the vacuum chamber  60  may be supplied or blocked by controlling the first and second control units  90   a  and  90   b.    
         [0055]    In a case where a coating portion  100   a  (see  FIG. 7 ) is formed, the first and second control units  90   a  and  90   b  are controlled in the state where air is blocked from the vacuum chamber  60  and the sound pressure generating unit  80  so that the sound pressure is operated to the vacuum chamber  60 . 
         [0056]    In this instance, the first control unit  90   a  may be controlled so that the vacuum chamber  60  is connected to the sound pressure generating unit  80 . The first control unit  90   a  may control openings/closings in three directions A, B and C: the vacuum chamber  60  (A), the sound pressure generating unit  80  (B) and a first air supply unit  91   a  (C). That is, while the coating portion  100   a  is formed, the first control unit  90   a  may open A and B and close C. 
         [0057]    The second control unit  90   b  may also be controlled so that the vacuum chamber  60  is connected to the sound pressure generating unit  80 . The second control unit  90   b  may control openings/closings in three directions D, E and F: the vacuum chamber  60  (D), the sound pressure generating unit  80  (E) and a second air supply unit  91   b  (F). That is, while the coating portion  100   a  is formed, the second control unit  90   b  may open D and E and close F. 
         [0058]    Accordingly, the sound pressure can be formed in the vacuum chamber  60  when the coating portion  100   a  is formed. 
         [0059]      FIG. 6  is a block diagram showing a state where air is inhaled into the vacuum chamber system of the coating apparatus according to the embodiment of the present invention. 
         [0060]    Referring to  FIG. 6 , in a case where a non-coating portion  100   b  (see  FIG. 7 ) is formed, the first and second control units  90   a  and  90   b  are controlled in the state where air is independently inhaled into the vacuum chamber  60  and the sound pressure generating unit  80 . 
         [0061]    In this instance, the first control unit  90   a  may control the air to be inhaled into the vacuum chamber  60  while blocking the vacuum chamber  60  and the sound pressure generating unit  80 . The first control unit  90   a  may control the openings/closing in the three directions A, B and C: the vacuum chamber  60  (A), the sound pressure generating unit  80  (B) and the first air supply unit  91   a  (C). That is, while the non-coating portion  100   b  is formed, the first control unit  90   a  may control the air to be inhaled by opening A and C and closing B. 
         [0062]    The second control unit  90   b  may control the air to be independently inhaled into the buffer tank  70  and the sound pressure generating unit  80  while blocking the vacuum chamber  60  and the sound pressure generating unit  80 . The second control unit  90   b  may control the openings/closing in the three directions D, E and F: the vacuum chamber  60  (D), the sound pressure generating unit  80  (E) and the second air supply unit  91   b  (F). That is, while the non-coating portion  100   b  is formed, the second control unit  90   b  may control the air to be inhaled by opening E and F and closing D. 
         [0063]      FIG. 7  is a plan view showing a state a material is coated using the vacuum chamber system of the coating apparatus according to the embodiment of the present invention. 
         [0064]    Referring to  FIG. 7 , a coating solution is intermittently coated on a base material. In this instance, the base material  10  is transferred from the left to the right, and a coating portion  100   a  and a non-coating portion  100   b  are alternately formed. If coating is performed using the vacuum chamber system of the coating apparatus according to this embodiment, an attraction phenomenon is less likely to occur at an end portion H of the coating portion  100   a  as shown in  FIG. 7 . 
         [0065]    As described in  FIGS. 5 and 6 , while the coating portion  100   a  is formed (G to H), the first and second control units  90   a  and  90   b  control the air to be blocked from the vacuum chamber  60  and the sound pressure generating unit  80 . While the non-coating portion  100   b  is formed (H to I), the first and second control units  90   a  and  90   b  control the air to be independently inhaled into the vacuum chamber  60  and the sound pressure generating unit  80 . Accordingly, it is possible to prevent the attraction phenomenon from occurring at the end portion H of the coating portion  100   a.    
       Exemplary Embodiment 
       [0066]    In intermittent coating using the vacuum chamber system of the coating apparatus according to this embodiment, the intermittent coating is performed in a coating thickness of 100 μm at a coating speed of 5.3 m/min using a slurry with a viscosity of 1500 cPs. In this instance, the coating portion  100   a  has a width of 5 m and the non-coating portion  100   b  has a width of 1 m. 
         [0067]    In a case where the vacuum chamber  60  is not used, the length of the end portion of the coating portion  100   a  at which the attraction phenomenon occurs is less than 0.5 mm, which is very small. However, in a case where the intermittent coating is performed using the vacuum chamber  60 , the length of the end portion of the coating portion  100   a  at which the attraction phenomenon occurs is about 2 mm. In this instance, the sound pressure of the vacuum chamber  60  is 0.3 kPa. 
         [0068]    In order to improve the attraction phenomenon that occurs at the end portion of the coating portion  100   a , coating is performed using the vacuum chamber system according to this embodiment, and the attraction length of the end portion of the coating portion  100   a  is measured. The measured attraction length of the end portion of the coating portion  100   a  is 0.5 mm, which is restored to the attraction length when the vacuum chamber  60  is not used. 
         [0069]    Hereinafter, the operation of the vacuum chamber system of the coating apparatus according to this embodiment will be described. 
         [0070]    In the vacuum chamber system of the coating apparatus, the first and second control units  90   a  and  90   b  are provided between the vacuum chamber  60  and the buffer tank  70 . The first and second control units  90   a  and  90   b  control the air to be independently inhaled to the vacuum chamber  60  and the sound pressure generating unit  80 . 
         [0071]    The first and second control units  90   a  and  90   b  may be automatically configured to operate in conjunction with an intermittent coating process. When the coating is performed, air is not inhaled into the vacuum chamber  60  and the sound pressure generating unit  80 , but sound pressure is formed in the vacuum chamber  60 . That is, the air in the vacuum chamber  60  is attracted to the side of the sound pressure generating unit  80 . 
         [0072]    When a coating solution is blocked to perform the intermittent coating, the first and second control units  90   a  and  90   b  control the air to be independently inhaled into the vacuum chamber  60  and the sound pressure generating unit  80 . That is, the air is independently inhaled into the vacuum chamber  60  and the sound pressure generating unit  80 , so that the air in the vacuum chamber  60  is not inhaled into the sound pressure generating unit  80 . In this instance, the air of the first air supply unit  91   a  connected to the first control unit  90   a  is inhaled into the vacuum chamber  60  so that the sound pressure is removed. The air of the second air supply unit  91   b  connected to the second control unit  90   b  is inhaled into the sound pressure generating unit  80 . 
         [0073]    Here, it is likely that an offset is provided at the times when the first and second control units  90   a  and  90   b  are on/off, respectively. Accordingly, a unit for finely adjusting the times when the first and second control units  90   a  and  90   b  are on/off, respectively, may be additionally provided. 
         [0074]    In a case where a coating portion  100   a  and a non-coating portion  100   b  are formed through the aforementioned process and a coating portion  100   a  is the formed again, coating is performed in the state that the positions of the first and second control units  90   a  and  90   b  is returned to the original positions, respectively. 
         [0075]    While the present invention has been described in connection with certain exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, and equivalents thereof.