KR101873154B1

KR101873154B1 - Roll to roll Silver Mirror Coating Apparatus and Silver Mirror Coating Method using Thereof

Info

Publication number: KR101873154B1
Application number: KR1020170041326A
Authority: KR
Inventors: 이기학; 윤재훈
Original assignee: 주식회사 씨에프티
Priority date: 2017-03-31
Filing date: 2017-03-31
Publication date: 2018-07-02

Abstract

The present invention relates to a roll-to-roll silver film coating apparatus, capable of realizing continuous or high speed coating for a flexible base, and a silver film coating method using the same. According to one embodiment of the present invention, the roll-to-roll silver film coating apparatus comprises: a substrate unwinding unit to continuously feed a substrate to a silver film coating line, in which a silver film coating work for the substrate is advanced; a surface modification unit to modify a surface of the substrate in order to secure bonding force between silver and the substrate fed from the unwinding unit; a silver film coating tank, wherein a silver mirror reaction solution and a reducing agent are stored and the substrate completing a substrate surface modification step is immersed; a water washing tank, wherein deionized water is stored and the substrate completing a silver film coating step is immersed and washed; a drying unit to dry the substrate completing a washing process; and a rewinding unit disposed on a side opposite to an unwinding device to recover the substrate completing a drying process.

Description

[0001] The present invention relates to a roll-to-roll silver coating apparatus and a silver coating method using the silver-

More particularly, the present invention relates to a roll-to-roll film coating apparatus capable of continuous or high-speed coating of a flexible substrate by applying a roll-to-roll system, And a method of coating a silver film using the same.

As one of the conventional silver plating methods, there is a method of electroplating by forming a silver film by energizing a positive (+) power source and a negative (-) power source to a material to be processed and a metal material to be obtained in an electrolytic solution. This method requires heavy cost and facilities for treating wastewater because it releases heavy metals such as cyanide and hexavalent chromium which are harmful to the environment. It is not only a cause of environmental pollution but also applied to conductors, There was a problem.

In addition, the conventional silver electroplating film forming method as described above includes a vacuum deposition method in which a silver sealed film is deposited on the surface of a material by gasifying or ionizing metals and oxides by setting a certain sealed space in a vacuum state. There is a problem in that the facility investment cost is high and the productivity is low due to the limitation of the throughput.

Further, in the case of the substrate coated with the silver powder or the nanoparticles of silver mixed with the other organic material by spraying, knife coating or dipping, the silver density is relatively low and the binding force between the silver particles is low, There has been a limit in achieving effects such as conductivity, shielding ability, or antibacterial property. Korean Patent Laid-Open No. 10-2008-73995 (titled "vibration spraying type silver coating method and apparatus, published: 2008.08.12) discloses a vibration spraying gun capable of uniformly spreading a silver coating film liquid on a surface of a product through a vibrating spray gun A spraying type silver coating method and apparatus are disclosed.

SUMMARY OF THE INVENTION The present invention has been conceived in order to solve such problems, and it is an object of the present invention to provide a method and apparatus for continuous or high speed coating of a flexible substrate by applying a roll- A roll-to-roll silver film coating apparatus and a silver film coating method.

A roll-to-roll silver coating apparatus according to one aspect of the present invention includes a substrate unwinding unit for continuously supplying a substrate with a silver coating operation line on which a silver coating operation is performed on a substrate, A silver coating reaction tank containing a silver halide reaction liquid and a reducing agent and immersing a substrate after the substrate surface modification step is immersed in the substrate surface, A drying unit for drying the substrate having been subjected to the cleaning process; and a rewinding unit for recovering the substrate after the drying process is completed, the drying unit being located opposite to the unwinding device, .

The substrate surface modification unit may be any one of an atmospheric plasma, a frame plasma, a vacuum plasma, and a corona.

The silver coating bath may vibrate in a direction perpendicular to the advancing direction of the substrate in a state in which the substrate is immersed.

And a discharge port through which the silver halide reaction liquid and the reducing agent can be discharged may be provided on the inner wall of the predetermined height from the bottom of the silver coating vessel.

A water level sensor for measuring the water level of the silver cyanide reaction solution and the reducing agent in the silver coating bath and a pump for discharging the excess volume to the outside when the water level of the silver cyanide reaction solution and the reducing agent exceeds a predetermined value .

The silver coating vessel may further include a pressurizing unit to pressurize the substrate immersed in the silver coating bath so that the silver reaction liquid and the reducing agent penetrate into the inside of the substrate.

The pressing unit may include a mesh structure.

According to one aspect of the present invention, there is provided a roll-to-roll silver coating method comprising: a substrate unwinding step of continuously supplying a substrate with a silver coating operation line on which a silver coating process is performed on a substrate; A silver coating step of immersing the substrate having undergone the substrate surface modification step in a silver coating solution tank containing a silver halide reaction solution and a reducing agent; A washing step of immersing the base material in a dehydrated water containing deionized water and washing the base material, a drying step of drying the substrate after the washing step, and a rewinding step of winding the base material after the drying step is completed have.

The silver coating bath may vibrate in a direction parallel to or perpendicular to the advancing direction of the substrate in a state in which the substrate is immersed.

The apparatus may further include a pressurizing unit inside the silver coating vessel to press the substrate immersed in the silver coating bath during the silver coating process so that the silver halide reaction liquid and the reducing agent penetrate into the substrate more easily. .

The pressing unit may include a mesh structure.

According to the present invention, there is provided an environmentally-friendly roll-to-roll film coating apparatus and a silver coating apparatus capable of continuous or high-speed coating of a flexible substrate by applying a roll to roll system and producing or not emitting volatile organic compounds or poisons Method can be provided.

1 is a schematic view of a roll-to-roll silver coating apparatus according to an aspect of the present invention.
2 is a flow chart of a roll-to-roll silver coating method according to another aspect of the present invention.
3 to 5 are photographs of the nonwoven fabric before and after the roll-to-roll silver coating process of the present invention,
6 is a photograph of a urethane foam before and after the process according to the roll-to-roll silver coating method of the present invention,

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention may be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. The shape and the size of the elements in the drawings may be exaggerated for clarity and the same elements are denoted by the same reference numerals in the drawings.

1 is a schematic view of a roll-to-roll silver coating apparatus according to an aspect of the present invention. 1, the roll-to-roll film coating apparatus includes an unwinding unit 10, a substrate surface modification unit 20, a silver coating unit 30, a water treatment tank 32, a drying unit 50, and a rewinding unit 60 ).

The unwinding unit 10 continuously supplies the base material 12 to the silver coating processing operation line where the coating operation is performed on the base material 12 to be subjected to the silver coating. The base material 12 may have various materials and thicknesses and includes fibers, leather, artificial leather, non-woven fabric, and the like. Thicknesses can range from a few micrometers to tens of millimeters. It is preferable that the inner and outer surfaces of the base material 12 are in contact with or not contaminated with other foreign substances that interfere with the formation of the silver film in the state immediately after production.

The substrate surface modifying unit 20 is a unit for modifying the surface of the substrate 12 in order to secure the adhesion of silver to the substrate 12 supplied from the unwinding device. The surface modifying unit is a plasma processing apparatus for modifying the surface of the substrate 12 by plasma for securing the adhesion between the substrate 12 and the silver coating. The surface modifying unit is a plasma processing apparatus for modifying the surface of the substrate 12 by using atmospheric plasma (atmospheric pressure plasma apparatus) , Or by vacuum plasma. Here, in the case of surface modification by atmospheric plasma, a plasma is formed in the atmosphere or atmospheric pressure by electric discharge in the air or atmospheric pressure, and the plasma reacts violently with the surface molecules of the substrate 12 to change the surface molecular structure In the case of surface modification by frame plasma, oxygen or oxygen in the atmosphere is oxidized in the air at normal temperature and atmospheric pressure to form a plasma through the flame treatment to react with the surface of the substrate 12 to change the surface molecular structure. It is possible to form a plasma by discharge in a vacuum chamber and react with the surface molecules of the substrate 12 to change the surface molecular structure. It is preferable that the interval between the plasma knob and the substrate 12 designed to correspond to the width of the substrate 12 passing under the substrate surface modification unit 20 is within 10 mm. For the substrate surface modification process by plasma, the thickness of the substrate 12 is preferably 3 mm or less.

The silver coating tank contains a silver halide reaction liquid and a reducing agent, and is a place where silver halide coating is performed by immersing the substrate 12 after the substrate surface modification step. In order to uniformly form a silver film on the substrate 12 to be silver-coated, silver nitrate was dissolved in deionized water together with a sodium hydroxide aqueous solution or an aqueous potassium hydroxide solution, and then an aqueous solution of a reducing agent such as sodium gluconate prepared by adding ammonia water was applied to a silver coating 30) so as to deposit a silver film so as to deposit silver. At this time, the silver nitrate solution and the reducing solution are added at appropriate ratios according to the kind of the substrate 12 and the coating speed. Meanwhile, the silver coating bath 30 may be formed in duplicate so that the temperature of the mixed solution of the silver halide reaction solution and the reducing agent aqueous solution in the silver coating coating tank 30 is in the range of 15 to 45 ° C, or a temperature control device can do. In an embodiment, the silver coating solution 30 may be mixed with the silver coating solution so that silver precipitates to the inside of the base material 12 while the mixed solution in the silver coating coating solution 30 gradually flows along the progressing direction of the base material 12, It can vibrate lightly by intensity. At this time, the oscillation of the silver film coating tank 30 is preferably 10 to 120 times / minute, and the oscillation reciprocating distance is about 10 to 50 mm. The vibrating direction of the silver coating coating vessel 30 may be parallel to the conveying direction of the substrate, or may be vibrated in the direction perpendicular to the conveying direction of the substrate (left or right direction) have. The silver halide reaction liquid and the reducing agent mixed solution in the silver coating bath 30 may be maintained at a predetermined level at the left and right sides of the silver coating vessel 30 at the end of the substrate 12 in the traveling direction and in the inner wall of the traveling direction silver coating vessel 30 (Not shown) so that the solution can flow out at a predetermined height. Or a water level sensor (not shown) may be installed to pump the excess volume to the waste solution collecting tank (not shown) by pumping the excess volume to maintain the water level of the mixed solution. In order to improve the coating efficiency with respect to substrates of various thicknesses, it is preferable that the level of the silver halide reaction solution and the reducing agent can be finely adjusted freely. To this end, a variable height take-off hose (not shown) may be connected to the membrane coating tank, and an auxiliary discharge pump (not shown) may be installed. The collected waste liquid is subjected to a purification treatment process in a state in which the outflow to the outside is blocked, so that leakage of the chemical substance can be prevented thoroughly. Further, the odorous or minute gas generated during the process is also sucked into the concentrated exhaust duct (not shown), purified through the nonwoven fabric and the carbon filter, and then subjected to the exhaust treatment. On the other hand, the silver coating bath 30 in which the silver halide reaction solution and the reducing agent are supplied is maintained at a slope angle of 0.1 to 5 degrees with respect to the substrate entering portion and the advancing portion so that the solution can easily flow out when the filtrate exceeds the appropriate water level.

Table 1 is an embodiment of a silver coating agent.

Ingredients Weight ratio (wt%) Silver complex aqueous solution ^{* 1)} 40 to 90 Reducing agent ^{* 2)} 60-10 Sum 100 * 1) A 1 molar aqueous solution of silver nitrate is prepared by mixing 1 molar aqueous solution of potassium hydroxide.
* 2) A 1 molar aqueous solution of sodium gluconate is used.

Meanwhile, the silver coating vessel 30 may further include a pressing unit (not shown). A pressurizing unit (not shown) may assist in facilitating the uniform penetration of the solution of the silver coating bath 30 into the substrate 12. [ The pressurizing unit (not shown) can operate lightly up and down in a mesh structure according to the thickness and shape of the substrate 12. [ The mesh size of the mesh is preferably 2 to 6 mm, and the mesh material is preferably made of a material hard to fix silver particles, such as nylon or Teflon.

The water treatment tank 32 is a place where deionized water is contained and the base material 12 having been subjected to the silver film coating step is immersed and washed. The electric resistance value of the deionized water used as the washing water is 4 to 18 MΩ. The water treatment tank 32 is inclined by about 0.1 to 5 degrees in the direction opposite to the silver coating bath 30 and is vibrated more strongly than the vibration in the silver coating tank 30, Wash out the reaction filtrate. When the number of the water treatment tanks 32 is one or more, and the cleaning of the substrate 12 is insufficient by one time, the water washing tank 32 is added to perform cleaning.

In the next step, the cleaned base material 12 is pressed by the pressing roller 14 to remove a large amount of water, and air, which has been removed from the air injection device 40 by removing air, oil, moisture, The water of the substrate 12 is blown out secondarily. Then, the base material 12 is passed through the drying unit 50 to remove moisture remaining in the inside and outside of the fabric, thereby firmly sintering the silver film. The drying unit 50 can continuously blow hot air of 30 to 90 DEG C against the substrate 12. [ The time for the substrate 12 to stay in the drying unit 50 may be from 10 minutes to 120 minutes.

The substrate 12 having passed through the drying unit 50 is wound again by the rewinding unit 60 and recovered. The rewinding unit 60 serves to recover the substrate 12, which has been subjected to the silver coating process, in a roll form in the coating operation line. The unwinding unit 10 serves to supply the substrate 12 to the silver coating line, while the rewinding unit 60 serves to recover the substrate 12 after the silver coating process has been completed, But the same structure can be applied.

2 is a flow chart of a roll-to-roll silver coating method according to another aspect of the present invention. Referring to FIG. 2, first, the substrate unwinding unit continuously supplies a substrate to a silver coating operation line where a silver coating process is performed on a substrate (S100). The supply of the substrate continues as long as the substrate on the reel is exhausted or maintenance of the equipment does not proceed.

Next, the surface of the substrate is modified by the substrate surface modifying unit to secure adhesion between the substrate and silver (S200). The substrate surface modification process may be any one of an atmospheric plasma, a frame plasma, a vacuum plasma, and a corona.

Subsequently, the substrate having undergone the substrate surface modification step is immersed in a silver coating bath containing a silver halide reaction solution and a reducing agent to coat the substrate with a silver coating (S300). The silver coating vessel can vibrate in a state in which the substrate is immersed, thereby allowing silver to penetrate well into the inside of the substrate. The vibrating direction of the silver coating coating vessel 30 may be parallel to the conveying direction of the substrate, or may be vibrated in the direction perpendicular to the conveying direction of the substrate (left or right direction) have.

In one embodiment, the pressurized unit is further included in the silver coating bath to pressurize the substrate immersed in the silver coating bath so that the silver reaction liquid and the reducing agent penetrate into the inside of the substrate. The pressing unit may be in the form of a mesh. The mesh material is preferably made of a material hard to fix silver particles, such as nylon or Teflon.

Next, the substrate having undergone the silver coating process is immersed in a water bath containing deionized water and washed (S400). The cleaning process (S400) is performed more than once. If the cleaning process is insufficient for removing the residues by one time cleaning with respect to the substrate, the cleaning process (S400) is repeated by adding several water baths.

Next, the substrate having undergone the cleaning process is dried (S500). After the cleaning process is completed, the base material is pressed by the pressing roller 14 to remove a large amount of water, and air, which has been subjected to the air purification treatment, is removed from the air injection device 40, ) In the second order. Then, the base material 12 is passed through the drying unit 50 to remove moisture remaining in the inside and outside of the fabric, thereby firmly sintering the silver film. The drying unit 50 can continuously blow hot air of 30 to 90 DEG C against the substrate 12. [ The time for the substrate 12 to stay in the drying unit 50 may be from 10 minutes to 120 minutes.

Next, the substrate on which the drying process is completed is wound around the rewinding unit to recover (S600).

FIGS. 3 to 5 are photographs of the nonwoven fabric before and after the step (a) and the step (b), respectively, according to the roll-to-roll silver coating method of the present invention. a) before the process and after the process (b)

Table 2 is the electrical resistance values of the substrate before and after the process according to the roll-to-roll silver coating method according to one embodiment of the present invention.

Type of substrate Electric resistance value before coating Electric resistance value after coating Nonwoven fabric A ∞ 0.2 to 0.5Ω Nonwoven fabric B ∞ 1 to 3 Ω Urethane foam film A ∞ 9 to 15Ω Urethane foam film B ∞ 45 to 90Ω

Measured with 3244 HiTESTER manufactured by HIOKI, Japan

Referring to Table 1, it can be seen that the electric resistance value of the substrate after the process according to the roll-to-roll silver coating method of the present invention has improved the electric conductivity.

Table 3 shows the potential difference measurements of the substrate before and after the process according to the roll-to-roll silver coating method according to one embodiment of the present invention.

Type of substrate Potential difference measurement before coating Potential difference measurement after coating Nonwoven fabric A -1.26 KV + 0.01KV Nonwoven fabric B + 3.5KV + 0.08KV Urethane foam film A + 0.19KV + 0.03 KV Urethane foam film B + 1.12KV + 0.04KV

Measured by FMX-004 Electrostatic Fieldmeter manufactured by SIMCO, Japan

Referring to Table 2, it can be confirmed that the electrical conductivity of the base material is significantly improved because the uniformity of the potential difference of the base material after the process according to the roll-to-roll silver coating method of the present invention is significantly improved.

The present invention is not limited to the above-described embodiments and the accompanying drawings. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims, .

10: Unwinding unit 12: Base
14: Compression roller 20: Substrate surface modification unit
30: Silver coating tank 32:
40: air injector 50: drying unit
60: rewinding unit

Claims

An unwinding unit for continuously supplying a substrate with a silver coating operation line on which a silver coating process is performed on the substrate;
A base material surface modification unit for modifying the surface of the base material to secure adhesion to the base material supplied from the unwinding unit;
A silver film coating tank containing a silver halide reaction liquid and a reducing agent and immersed in the substrate after the substrate surface modification step and vibrating in a direction parallel or perpendicular to the advancing direction of the substrate in a state in which the substrate is immersed;
A water bath containing deionized water and immersed in the substrate after the immersion process in the silver coating bath;
A drying unit for drying the substrate that has undergone the cleaning process in the water treatment tank; And
And a rewinding unit located on the opposite side of the unwinding unit for winding and recovering a substrate having been dried in the drying unit.

The method according to claim 1,
Wherein the substrate surface modifying unit is any one of an atmospheric plasma, a frame plasma, a vacuum plasma, and a corona.

delete

The method according to claim 1,
A water level sensor for measuring a water level of the silver halide reaction solution and the reducing agent in the silver coating bath; And
And a pump for discharging an excess volume of the silver halide reaction solution and the reducing agent to the outside of the silver coating bath when the water level of the silver halide reaction solution and the reducing agent exceeds a preset value of the water level sensor.

The method according to claim 1,
Further comprising a pressurization unit inside the silver coating vessel to pressurize the substrate immersed in the silver coating bath so that the silver reaction liquid and the reducing agent penetrate into the inside of the substrate more effectively.

The method according to claim 6,
Wherein the pressing unit includes a mesh structure.

A substrate unwinding step of continuously supplying a substrate through an unwinding unit to a silver coating operation line on which a silver coating process is performed on the substrate;
A base material surface modification step of modifying the surface of the base material to secure adhesion to the base material supplied from the unwinding unit;
A silver coating step of immersing the substrate which has undergone the substrate surface modification step in a silver coating bath containing a silver halide reaction liquid and a reducing agent and oscillating in a direction parallel or perpendicular to the progress of the substrate in a state in which the substrate is immersed;
A washing step of immersing the substrate having undergone the silver coating process in a water bath containing deionized water to wash the substrate;
A drying step of drying the substrate after the washing step; And
And a rewinding step of winding and recovering the substrate on which the drying step has been completed.

delete

9. The method of claim 8,
And a pressurizing unit for further pressurizing the base material immersed in the silver coating bath during the silver coating process so as to allow the silver halide reaction liquid and the reducing agent to penetrate into the inside of the base material more preferably, By weight.

11. The method of claim 10,
Wherein the pressing unit comprises a mesh structure.