KR20230071507A - Roll-to-roll lamination process control method - Google Patents

Abstract

The present invention relates to a roll-to-roll lamination process control method, which is provided to perform a lamination process while a material is moved between rolls. In particular, the present invention relates to a roll-to-roll lamination process control method, which comprises: an initial value determination step of determining the initial value of the material and the rolls to determine the optimal operation condition initialization; a driving tension monitoring step of monitoring the driving tension value of the material after the initial value is determined in the initial value determination step; a driving tension control step of controlling the driving tension value such that the driving tension value may be operated in the range of a critical minimal driving tension value and a critical maximal driving tension value to be operated in a crease prevention area; a crease monitoring step of checking the image of the material to determine whether creases are caused at the material, which may be caused while the material is moved between the rolls; and a crease prevention control step of controlling after determining whether creases are caused in the material recognized in the crease monitoring step. Therefore, failures in lamination may be minimized.

Description

Roll-to-roll lamination process control method {Roll-to-roll lamination process control method}

The present invention is for a smart lamination system for manufacturing a roll-to-roll solar cell, and more specifically, when a lamination process is required in a process of producing a solar cell through roll-to-roll coating or printing, several substrates have defects such as wrinkles. It relates to a smart lamination system that allows lamination without this.

In general, when manufacturing a solar cell using a roll-to-roll method (described as an example), a process of laminating several substrates is necessarily accompanied. In the process of laminating several substrates of different materials, various quality defects such as wrinkles and bubbles occur after lamination depending on the tension, strain, and meandering characteristics of each substrate. Recently, various types of methods and techniques for minimizing such roll-to-roll lamination defects have been developed.

Background art is as follows when described by the applicant of the present application and registered No. 10-1247184 (2013.03.25).

5 is a flowchart showing a method for setting driving tension according to the background art.

First, the operating speed is determined in consideration of the drying temperature and time. (Step S10) In step S10, the operating speed is determined in consideration of the drying time and temperature according to the type of ink used and the length of the dryer.

Next, the operating tension for preventing slip is determined using the slip simulation. (Step S20)

In step S20, the driving tension for preventing slip is determined through simulation using the mathematical modeling presented in FIGS. 5A and 5B.

Then, it is determined whether peeling experiment data exists. (Step S30)

In step S30, it is determined whether there is the degree of peeling (%) obtained by using the peeling test of the final product and the peeling degree (ASTM class) data presented in ASTM D 3359, which is a peeling test standard.

If there is no peel test data, a peel test is performed. Prior to performing the peel test, the maximum bending radius occurring in the roll-to-roll process is determined (step S40).

Next, the operating tension factor to be applied to the peeling test is determined within the elastic limit. (Step S50)

Here, when determining the driving tension factor, it is preferable to determine two or more driving tension factors. That is, the maximum operating tension and the minimum operating tension are determined. Here, the minimum operating tension corresponds to the operating tension for preventing slip determined in step S20.

The maximum operating tension is determined as a percentage of the permissible yield stress of the laminate film, for example 10%.

Then, a peeling test is conducted, and the degree of peeling is determined. (Step S60)

The peeling test in step S60 is performed according to the sequence shown in FIG. 6 .

However, this device considered the operating tension setting method to prevent slip in the rewinding section, but the lamination system, such as the mechanical properties of each material for the laminating process, the operating tension range, and the operating speed, can prevent lamination defects from occurring. couldn't

The present invention has been made to solve the above problems, and an object of the present invention is to provide a roll-to-roll lamination control method.

Korea Intellectual Property Office Patent Registration No. 10-1256790 (2013.04.19) Republic of Korea Intellectual Property Office Patent Registration No. 10-1247184 (2013.03.25) Korea Intellectual Property Office Patent Registration No. 10-1671902 (2016.11.03) Korean Intellectual Property Office Publication No. 10-2020-0099393 (2020.)

The problem to be solved by the present invention is to solve the problem of enabling the lamination system to minimize lamination defects, such as the mechanical properties of each material for the laminating process, the operating tension range, and the operating speed through the roll-to-roll lamination process control method.

In order to solve the above problems, it has the following configuration.

In the roll-to-roll lamination process control method for performing the lamination process while the material moves between the rolls,

an initial value determination step of determining initial values of the material and the roll in order to optimally determine initialization of operating conditions;

a driving tension monitoring step of monitoring a driving tension value of the material after determining an initial value in the initial value determining step;

a driving tension control step of controlling the driving tension value so that the driving tension value is driven within a range of the threshold minimum driving tension value and the threshold maximum driving tension value and operated in an anti-wrinkle region;

A wrinkle monitoring step of checking an image of the material to determine whether or not the material is wrinkled while the material moves between the rolls;

It is characterized by a roll-to-roll lamination process control method having a wrinkle prevention control step of determining and controlling whether or not the material identified in the wrinkle monitoring step has wrinkles.

Here, the initial value determination step includes a material characteristic identification step of identifying the characteristics of the material;

Driving tension range setting step of setting the driving tension of the material to prevent deformation of the material;

A roll material friction coefficient measuring step for calculating a dynamic friction coefficient between the roll and the material by measuring a static friction coefficient between the roll and the material, roll roughness, and material roughness;

a material width and thickness characteristic determination step of determining a width of the material and a thickness characteristic of the material;

Critical tension for calculating the critical minimum driving tension function of the material, the critical maximum driving tension function of the material, and the roll misalignment critical distance function as a function to be calculated to keep the feed of the material stable and uniform within the wrinkle prevention area. distance function calculation step;

A material driving speed setting step of setting a driving speed of the material;

It is preferable to include an operating tension range setting step of determining an operating tension range through the critical minimum driving tension function and the critical maximum driving tension function.

Here, in the driving tension control step, when driving out of the wrinkle prevention area, it is preferable to perform feedback control through the tension control step.

Here, when wrinkles occur in the wrinkle prevention control step, it is preferable to perform feedback control through an AMBR (Active Motion Based Roller) control step.

Here, in the roll material friction coefficient measurement step, the static friction coefficient ( μ _st ), roll roughness ( Rq _roll ) and the material roughness ( Rq _web ) are calculated by Equations (1), Equations (2) and Equations (3) Through, the dynamic friction coefficient (μ _T ) between the roll and the material is calculated by the following function.

(1)

(One)

(2)

(2)

(3)

(3)

here,

μ _T : the dynamic friction coefficient

μ _st : the static friction coefficient

Rq : The equivalent surface roughness [m]

Rq _web : The web surface roughness [m]

Rq _roll : The roller surface roughness [m]

h ₀ : air gap between the roll and the material (the air gap between the roller and the web)

R : roll radius

W : board width (web width [m])

V : Material speed [m/s]

T : operating tension [N]

Here, in the critical tension distance function calculation step, the critical minimum driving tension function (T _slip ) of the material and the critical maximum driving tension function (T _cr ) and the roll misalignment critical distance function (Δd _cr ) are calculated, but the function values calculated by Equations (4), Equations (5) and Equations (6) are calculated.

(4)

(4)

(5)

(5)

(6)

(6)

(7)

(7)

(8)

(8)

here,

θ _cr : The critical roll misalignment angle [rad]

τ _cr : The critical shear stress [N/m ² ],

L : span length [m]

W : material width (web width [m])

E : Young modulus of web [N/m ² ]

ν: Poisson's ratio [ν] of web

t : material thickness (thickness of web [m])

T : operating tension [N]

η _air : dynamic viscosity of air; = 3.077e-7 [N·min/m ² ] at 27℃

Here, in the wrinkle monitoring step, it is preferable to additionally include a warning generating step when there is a wrinkle defect through monitoring in real time.

The effect of the invention is to optimally set the initialization of operating conditions so that the lamination system can minimize lamination defects such as mechanical properties of each material, operating tension range, and operating speed for the laminating process through the roll-to-roll lamination process control method. During the lamination process, lamination defects such as wrinkles can be monitored in real time, prevented in advance, and can be controlled to be minimized.

1 and 2 are diagrams showing a flow chart of a method constituting the present invention.
Figure 3 is a view showing that the material is wrinkled between rolls.
Figure 4 is a view showing the wrinkle prevention area.
Figure 5 is a diagram showing the background art.

The smart lamination system refers to the process of producing a solar cell through roll-to-roll coating or printing using roll-to-roll lamination (shown as an example). It refers to lamination without it.

In addition, the span between the rolls 20 and the rolls 20 is referred to as a span area.

The present invention has the following steps.

The smart lamination process for roll-to-roll solar cell production (a solar cell is an example of the lamination process, and it is applied to all devices requiring a lamination process.) The lamination system, such as speed, sets the initialization of operating conditions optimally so that lamination defects can be minimized.

In addition, through the smart lamination system, the surface wrinkling state of the material can be identified in real time, and the operator can grasp the wrinkling state in real time through an alarm when wrinkling occurs. In addition, through meandering control according to the direction of wrinkles and automatic control of appropriate drive tension suitable for the wrinkle prevention area, it is possible to restore from a wrinkled state to a normal state.

1 and 2 will be described step by step as follows.

In the roll-to-roll lamination process control method for performing the lamination process while moving the material 10 between the rolls 20, the initial values of the material 10 and the roll 20 are optimally set to initialize operating conditions. Has an initial value determination step for determining (S100)

Here, the initial value determining step (S100) includes the following steps.

The following steps are not necessarily performed in sequence, and it does not matter if the order of the flowchart is partially reversed.

It has a material characteristic identification step of identifying the characteristics of the material 10. (S110)

Identify Young's modulus [E], Yield stress [σ _Y ], and Poisson's ratio [ν], which are the characteristics of different materials used in lamination. Use ASTM D638 or ASTM E345, which are standard tests used to characterize plastic or iron foils.

In order to prevent deformation of the material 10, it has a driving tension range setting step of setting the driving tension of the material 10. (S120)

Set the driving tension range to prevent plastic deformation of the material. Tension is determined within the range of 10% to 20% of the yield stress (yield stress [σ _Y ]). Tension can be calculated as the product of the material's cross-sectional area and stress.

Between the roll 20 and the material 10 through the measurement of the static friction coefficient (μ _st ), roll roughness ( Rq _roll ) and material roughness ( Rq _web ) between the roll 20 and the material 10 It has a roll material friction coefficient measurement step for calculating the dynamic friction coefficient (μ _T ). (S130)

Determine the frictional force [μ _T ] between the roll and the material. The static friction coefficient (μ _ST) is measured using the ASTM G143 test, and the material roughness (Rq _web) and roll roughness (Rq _roll) characteristics are used as in Equations 1 to 3.

In addition, in the roll material friction coefficient measurement step (S130), the static friction coefficient (μ _st ), roll roughness ( Rq _roll ) and the material roughness ( Rq _web ) are Equation (1), Equation (2) and Equation (3) ) The dynamic friction coefficient (μ _T ) between the roll 20 and the material 10 through calculation is calculated by the following function.

(1)

(One)

Here, the dynamic friction coefficient μ _T has the same value as the static friction coefficient μ _st when h ₀ < Rq .

h ₀

3Rq 인 경우에는 동적마찰계수μ_T는 Rq

h ₀

In the case of 3Rq , the dynamic friction coefficient μ _T is

의 값과 같다.

is equal to the value of

The dynamic friction coefficient μ _T has a value of 0 when h _{0 >} 3 Rq .

Here, h _{0 and} Rq are as follows.

(2)

(2)

(3)

(3)

here,

μ _T : the dynamic friction coefficient

μ _st : the static friction coefficient

Rq : The equivalent surface roughness [m]

Rq _web : The web surface roughness [m]

Rq _roll : The roller surface roughness [m]

h ₀ : air gap between the roll and the material (the air gap between the roller and the web)

R : roll radius

W : board width (web width [m])

V : Material speed [m/s]

T : operating tension [N]

_Equation 1 is a relational expression for obtaining the friction coefficient experimentally when air is introduced between a material with different surface roughness and a _roller . have

Equation 2 is an equation for determining the thickness of the air layer formed between the roll and the material, which is experimentally determined according to the width of the material used, the diameter of the roll that transports the material, the tension of the material, and the speed at which the material is transported.

The air layer thickness determined here is used to determine the coefficient of friction between the material and the roller in Equation 1.

Equation 3 is an equation that calculates the equivalent roughness between the material surface and the roll according to the roughness of the material surface and the roll surface, and is used to determine the dynamic friction coefficient of Equation 1.

It has a material width and thickness characteristic determination step of determining the width (W) of the material 10 and the thickness (t) of the material 10 (S140).

The critical minimum driving tension value (T _slip) and the critical maximum driving tension value (T _cr ) and a critical tension distance function calculation step of calculating a roll misalignment critical distance function (Δd _cr ) (S150).

An anti-wrinkle window (FIG. 3) is derived using Equations 4, 5, and 6.

The anti-wrinkle window is defined by the tension function of the material (T _slip , T _cr function in Equations 1 and 2) and the misalignment distance function (Δd _cr function in Equation 6).

The wrinkle free zone is divided into three lines, T _slip , T _{cr , and} Δd _cr , and in the wrinkle free zone, the material is transported in a stable and uniform state. If a material defect such as slip or wrinkle occurs, it means that it is outside the range of the wrinkle prevention window, and conversely, if there is a state outside the range of the wrinkle prevention window, a material defect can be inferred.

When the driving tension is greater than the critical minimum tension T _slip (Eq. 4) or less than the critical maximum tension T _cr (Eq. 5), the material operates normally without slipping or wrinkling. If the driving tension T is smaller than T _slip or larger than T _cr , wrinkles occur in the material. If the roll misalignment distance function Δd _cr (Eq. 6) is smaller than the material, the material is stably conveyed without creating shear wrinkles.

In the critical tension distance function calculation step (S150), the critical minimum driving tension function (T _slip ) of the material 10, the material Calculate the critical maximum driving tension function (T _cr ) and the roll misalignment critical distance function (Δd _cr ) of (10), but calculate the function value calculated by Equations (4), Equations (5) and Equation (6) .

The function values described below are mathematical models derived through experiments with respect to the surface roughness of the material and the roller, the conveying speed of the material, and the diameter of the roller.

here,

(4)

(4)

(5)

(5)

(6)

(6)

(7)

(7)

(8)

(8)

θ _cr : The critical roll misalignment angle [rad]

τ _cr : The critical shear stress [N/m ² ],

L : span length [m]

W : material width (web width [m])

E : Young modulus of web [N/m ² ]

ν: Poisson's ratio [ν] of web

t : material thickness (thickness of web [m])

T : operating tension [N]

η _air : dynamic viscosity of air; = 3.077e-7 [N·min/m ² ] at 27℃

Equation 4 is a slip tension determination equation determined experimentally according to the surface roughness of the material, the width of the material, the diameter and surface roughness of the roll that transports the material, and the speed at which the material is transported.

Equation 5 is a function determined through experiments considering the thickness of the material, the Poisson's ratio of the material, and the static and static friction coefficients between the material and the roller. Equation 2 is affected by the air gap between the material and the roller, which is experimentally determined according to the material width, tension, and material transport speed.

Equation 6 is the calculated circumferential travel at the end of the roll according to the misalignment angle (in radians) of the rolls across the span shown in Equation 7.

It is shown in Figure 2.

Equation 8 is an equation that defines the critical shear stress of a material considering the Poisson's ratio and thickness of the material.

As such, functions 4, 5, and 6 are relational expressions that must be experimentally determined when a lamination process is selected.

Wrinkles can be divided into two types: wrinkles caused by misalignment of rolls and wrinkles caused by driving tension. As the misalignment of the rolls increases downstream of the span in the material transport direction, the material shear stress increases. When the shear stress increases, the stress that causes plastic deformation of the material, that is, the critical buckling stress of the material, is exceeded and wrinkles occur in the material.

When the roll misalignment distance is greater than the critical misalignment distance (Δd _cr ) expressed by Equation 5 (300, 400), wrinkles occur.

An area below the critical misalignment distance (Δd _cr ) line is the anti-wrinkle area 100, which is an area where there are no wrinkles in the material moving on the span or on the roll.

Reference numeral 200 indicates that the material in the roll is not wrinkled in the anti-wrinkle area.

The higher the driving tension, the more the material can make the span wrinkle-free, and the higher tension is applied to eliminate the wrinkle in the span due to the misalignment distance of the rollers. However, if the drive tension is too high, creases will form on the roll. When tension is applied to the material, the material exerts pressure on the rolls and experiences a compressive stress supported by frictional forces between the material and the rolls. The compressive stress acts like a hoop stress in a thin-walled pressure cylinder vessel. The compressive stress of a material on a roll is proportional to the applied tension.

The compressive stress in the material goes to zero at the edges of the material width and increases along the center of the material with a slope determined by traction.

In addition, if the compressive stress of the material applied to the roll is greater than the critical buckling stress of the shell-type material, the material becomes unstable and wrinkles occur on the upper surface of the roll. Therefore, the driving tension should be smaller in order to prevent the material from being wrinkled in the roll.

It has a material driving speed setting step of setting the driving speed of the material 10. (S160)

Set the material speed [V] according to the needs of the production volume.

and an operating tension range setting step (S170) of determining an operating tension range through the critical minimum driving tension function (T _slip ) and the critical maximum driving tension function (T _cr ).

After the initial value is determined in the initial value determining step (S100), a driving tension monitoring step of monitoring the driving tension value of the material 10 is provided. (S200)

Tension is monitored through a load cell.

A driving tension control step of controlling the driving tension value so that the driving tension value is driven within the range of the threshold minimum driving tension value (T _slip) and the threshold maximum driving tension value (T _cr ) so that the driving tension value is operated in an anti-wrinkle region. Have (S300)

If the checked tension value satisfies T _slip < T _oper < T _cr , it goes to the next step. Otherwise, the driving tension must be controlled within the range of T _slip < T _oper < T _cr .

In the driving tension control step (S300), when driven outside the wrinkle prevention area 100, it is preferable to perform feedback control through the tension control step (S350).

In order to determine whether or not the material 10 is wrinkled while the material 10 moves between the rolls 20, a wrinkle monitoring step of checking an image of the material 10 is performed. (S400)

In the wrinkle monitoring step (S400), it is preferable to additionally have a warning generating step when there is a wrinkle defect through monitoring in real time.

Grasp the shape of the material through the camera. Administrators can recognize and respond to wrinkle defect states in real time.

It has a wrinkle prevention control step of determining and controlling whether or not the material 10 identified in the wrinkle monitoring step has wrinkles. (S500)

In addition, when wrinkles are generated in the wrinkle prevention control step (S500), it is preferable to perform feedback control through an AMBR (Active Motion Based Roller) control step (S550).

AMBR measures the degree of misalignment and controls the misalignment of the roll below the misalignment threshold where no creasing occurs.

According to FIG. 4, if the driving tension is controlled, it is within the range of 100 and 300, and the material in the span and roller is prevented from being wrinkled by the driving tension.

In the wrinkle prevention control step (S500), the misalignment of the rollers is controlled so that wrinkles do not occur.

Therefore, a wrinkle free zone (region 100 in FIG. 4) is realized by simultaneously monitoring and controlling the tension of the material and the misalignment of the roller in real time.

Area 200 in FIG. 4 is an area where wrinkles do not occur due to roller misalignment, but wrinkles occur in the roll due to excessive tension.

Area 300 in FIG. 4 is an area where wrinkles do not occur in the span due to tension, but wrinkles occur on the span due to excessive misalignment.

Area 400 in FIG. 4 corresponds to an area where wrinkles occur in the roll and span due to excessive tension and misalignment.

When the vision system detects a wrinkle defect, it measures the angle and sends the measured value to the meandering controller.

The meandering controller receiving the value prevents the wrinkle defect by controlling and compensating through logic. If no wrinkle defects are found, proceed to the next step.

If you want to repeat the control of the above process, it goes to the driving tension monitoring step (S200) of monitoring the driving tension value of the material (10).

If you do not proceed further, you move to the end stage.

The terms or words used in this specification and claims should not be construed as being limited to ordinary or dictionary meanings, and the inventors may appropriately define the concept of terms in order to explain their invention in the best way. It should be interpreted as a meaning and concept consistent with the technical idea of the present invention based on the principle that there is.

Therefore, the embodiments described in this specification and the configurations shown in the drawings are only one of the most preferred embodiments of the present invention, and do not represent all the technical ideas of the present invention, so at the time of this application, they can be replaced. It should be understood that there may be many equivalents and variations.

10: material 20: roll 100: non-wrinkled area
200: Wrinkles do not occur due to misalignment, but wrinkles occur in the roll due to excessive tension
300: Wrinkles are not generated in the span by tension, but wrinkles are generated on the span due to excessive misalignment.
400: Areas of wrinkles in rolls and spans due to excessive tension and misalignment

Claims (7)

In the roll-to-roll lamination process control method for performing the lamination process while the material moves between the rolls,
an initial value determination step of determining initial values of the material and the roll in order to optimally determine initialization of operating conditions;
a driving tension monitoring step of monitoring a driving tension value of the material after determining an initial value in the initial value determining step;
a driving tension control step of controlling the driving tension value so that the driving tension value is driven within a range of the threshold minimum driving tension value and the threshold maximum driving tension value and operated in an anti-wrinkle region;
A wrinkle monitoring step of checking an image of the material to determine whether or not the material is wrinkled while the material moves between the rolls;
A roll-to-roll lamination process control method having a wrinkle prevention control step of determining and controlling whether or not the material identified in the wrinkle monitoring step has wrinkles. The method of claim 1 , wherein the initial value determination step comprises: a material characteristic determination step of determining the characteristics of the material;
Driving tension range setting step of setting the driving tension of the material to prevent deformation of the material;
A roll material friction coefficient measuring step for calculating a dynamic friction coefficient between the roll and the material by measuring a static friction coefficient between the roll and the material, roll roughness, and material roughness;
a material width and thickness characteristic determination step of determining a width of the material and a thickness characteristic of the material;
Critical tension for calculating the critical minimum driving tension function of the material, the critical maximum driving tension function of the material, and the roll misalignment critical distance function as a function to be calculated to keep the feed of the material stable and uniform within the wrinkle prevention area. distance function calculation step;
A material driving speed setting step of setting a driving speed of the material;
A roll-to-roll lamination process control method comprising the step of setting an operating tension range for determining an operating tension range through the critical minimum driving tension function and the critical maximum driving tension function. 3. The roll-to-roll lamination process control method according to claim 1 or 2, wherein, in the driving tension control step, when the drive is driven outside the wrinkle prevention region, feedback control is performed through the tension control step. [Claim 3] The roll-to-roll lamination process control method according to claim 1 or 2, characterized in that the feedback control is performed through the AMBR control step when wrinkles are generated in the anti-wrinkle control step. The method of claim 2, wherein the static friction coefficient (μ _st ), roll roughness ( Rq _roll ) and the material roughness ( Rq _web ) in the roll material friction coefficient measuring step are Equations (1), Equations (2) and Equations (3) ) Through the calculation by the roll-to-roll lamination process control method, characterized in that the dynamic friction coefficient (μ _T ) between the roll and the material is calculated as a function as follows.
here,

(One)

(2)

(3)
μ _T : the dynamic friction coefficient
μ _st : the static friction coefficient
Rq : The equivalent surface roughness [m]
Rq _web : The web surface roughness [m]
Rq _roll : The roller surface roughness [m]
h ₀ : air gap between the roll and the material (the air gap between the roller and the web)
R : roll radius
W : board width (web width [m])
V : Material speed [m/s]
T : operating tension [N] The method of claim 2, wherein in the critical tension distance function calculation step, the critical minimum driving tension function (T_slip), the critical maximum driving tension function of the material (T_cr) and the roll misalignment critical distance function (Δd_cr), but calculating the function value calculated by Equation (4), Equation (5) and Equation (6).
here,

(4)

(5)

(6)

(7)

(8)
θ _cr : The critical roll misalignment angle [rad]
τ _cr : The critical shear stress [N/m²]),
L: span length (span length [m])
W: Board width (web width [m])
E: Young modulus of web [N/m²])
ν: Poisson's ratio [ν] of web
t: Thickness of web [m]
T: operating tension [N]
η _air : dynamic viscosity of air; = 3.077e-7 [N min/m²] at 27℃) The roll-to-roll lamination process control method according to claim 1, wherein the wrinkle monitoring step further includes a warning generating step when there is a wrinkle defect through monitoring in real time.

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