KR20220014200A - Method for separating back sheet from solar cell module - Google Patents

Abstract

The present invention, in a method for separating a back sheet from a waste solar module comprising a solar cell, an encapsulant covering the upper and lower portions of the solar cell, and a front sheet and a back sheet covering the encapsulant, comprises the following steps: (a) manufacturing a mixed solvent containing N-methyl-2-pyrrolidone (NMP); (b) heating the manufactured mixed solvent; (c) immersing the waste solar module in the heated mixed solvent; and (d) recovering the separated back sheet from the waste solar module.

Description

How to separate the backsheet from the waste solar module {METHOD FOR SEPARATING BACK SHEET FROM SOLAR CELL MODULE}

The present invention relates to a method of separating a back sheet from a waste solar module in order to recycle some materials constituting the waste solar module.

1 is a view showing a cross-section of a general solar module. Referring to FIG. 1 , the photovoltaic module 100 is formed of a photovoltaic cell 110 and EVA (ethylene vinyl acetate) material, and an encapsulation layer (hereinafter, the first The protective sheet (hereinafter, formed to cover the encapsulation layer 120 and the second encapsulation layer 130), and the first encapsulation layer 120 and the second encapsulation layer 130, and protects the solar cell 110 It is composed of a front sheet 140 and a back sheet 150), and the components are supported by a frame 160 made of an aluminum material.

In the photovoltaic module 100 , the protective sheet must be able to protect the solar cell 110 from external shocks or the environment while transmitting sunlight, so the front sheet 140 is formed of a tempered glass material, and the back sheet 150 ) may be formed of a synthetic resin material.

The photovoltaic module 100 is a semiconductor device that converts solar energy into electrical energy. It does not emit harmful substances in the process of generating power, so it is used as eco-friendly energy. Ways to deal with it are being discussed.

In processing the waste solar module, silicon constituting most of the solar cell 110 and silver included in the electrode, tempered glass constituting the front sheet 140, aluminum constituting the frame 160, etc. are very Since they are expensive materials or can be widely used, the components are classified as objects for recycling, and the first and second encapsulation layers 120 and 130 and the backsheet 150 made of EVA material are discarded.

Therefore, it is important to efficiently separate the components classified as recycling objects from the first and second encapsulation layers 120 and 130 and the back sheet 150 when processing the waste solar module.

For example, the encapsulation layer made of EVA material may be removed from the surface of the solar cell 110 through thermal decomposition. In detail, the EVA component constituting the encapsulation layer may be removed by heating the waste solar module at about 500° C. for 30 minutes to 5 hours. Alternatively, before heating the waste photovoltaic module, it may be further subjected to a process of treatment with an acid or alkali solution or an organic solution.

On the other hand, even in the case of the back sheet 150 made of a synthetic resin material, it can be separated and removed through thermal decomposition. However, the backsheet 150 generates a malignant gas during the heating process, and white dust remains, making it somewhat difficult to work.

Accordingly, a technology capable of separating the back sheet 150 without high temperature has been developed. After removing the back sheet 150 by grinding the surface on which the back sheet 150 is formed with a sawtooth-shaped blade, or by applying heat at a level of 100 ° C to the waste solar module to weaken the adhesive force of the adhesive in contact with the back sheet 150 The back sheet 150 may be removed.

However, the method using a sawtooth-shaped blade generates a large amount of dust during the grinding process of the back sheet 150, and there is a limitation in that the back sheet 150 cannot be completely separated from the waste solar module. In addition, the method of weakening the adhesive force of the adhesive in contact with the back sheet 150 is a configuration that can serve as a support layer when the back sheet 150 is removed when the tempered glass forming the front sheet 140 is damaged a lot. There is a problem that it does not exist.

Japanese Patent Publication No. 2012-19134 discloses a method of immersing a waste photovoltaic module in an aromatic organic solvent mixture to recycle the waste photovoltaic module and then irradiating ultrasonic waves to separate the components of the waste photovoltaic module. .

One object of the present invention is to provide a method for separating a backsheet from a waste solar module without heat treatment.

Another object of the present invention is to provide a method for separating a backsheet from a waste solar module regardless of whether the tempered glass is damaged.

The present invention provides a method for separating the back sheet from a waste solar module comprising a solar cell, an encapsulant covering the upper and lower portions of the solar cell, and a front sheet and a back sheet covering the encapsulant, (a ) preparing a mixed solvent containing NMP (N-methyl-2-pyrrolidone); (b) heating the prepared mixed solvent; (c) immersing the waste solar module in the heated mixed solvent; and (d) recovering the separated back sheet from the waste solar module.

In the present invention, the back sheet, a transparent film layer; a first coating layer disposed between the encapsulation layer and one surface of the transparent film layer; and a first coating layer disposed on the other surface of the transparent film layer, wherein the first coating layer and the second coating layer are separated in step (c).

In the present invention, the step (c) is characterized in that the first coating layer is separated after the second coating layer is separated.

In the present invention, the first coating layer and the second coating layer, TiO ₂ It is characterized in that the layer coated with the paste.

In the present invention, the mixed solvent of step (a) is characterized in that it is prepared by mixing toluene in NMP (N-methyl-2-pyrrolidone) solvent.

In the present invention, the mixed solvent of step (a) is characterized in that it is prepared by mixing ethyl acetate (EA) in NMP (N-methyl-2-pyrrolidone) solvent.

In the present invention, the mixed solvent, NMP (N-methyl-2-pyrrolidone) solvent and toluene or NMP (N-methyl-2-pyrrolidone) solvent and ethyl acetate (EA) are mixed in a ratio of 7 to 3 characterized in that it is manufactured.

In the present invention, the step (b) is characterized in that the mixed solvent is heated to 60 to 80 ℃.

In the present invention, the step (c) is characterized in that it proceeds for 1 hour 30 minutes to 3 hours.

The present invention can separate the backsheet from the waste photovoltaic module without modifying and damaging other components of the waste photovoltaic module.

In addition, the present invention can separate the back sheet from the waste solar module regardless of whether the tempered glass forming the front sheet is damaged.

1 is a view showing a cross-section of a general solar module.
FIG. 2 is a view showing a detailed structure of a back sheet constituting the solar module of FIG. 1 .
3 is a view showing a process of a method for separating a backsheet from a waste solar module according to the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The examples described below are only examples for describing the present invention in detail, and it will be apparent to those of ordinary skill in the art that the scope of the present invention is not limited by the examples.

In addition, all terms related to technology used herein have the same meaning as commonly understood by those of ordinary skill in the art unless otherwise defined herein, and if the meanings conflict, definitions The description of the present specification including

Meanwhile, in this specification, in order to clearly explain the invention shown in the drawings, descriptions related thereto are omitted, and similar reference numerals are used for similar components. And, when a component "includes" other components, this means that other components may be further included, rather than excluding other components, unless otherwise stated. Also, in the specification, when a “part” is described with respect to a certain component, it should be understood to mean one unit or block performing a specific function.

In addition, in the steps described in this specification, identification numbers (eg, first, second, etc.) are used for convenience of description and should not be limited to describing the order of each step, and each step is Unless a specific order is clearly indicated, the implementation may be performed differently from the specified order. That is, the steps may be performed in the same order as specified, may be performed substantially simultaneously, or may be performed in the reverse order.

The present invention proposes a method for separating a backsheet from a waste solar module. According to the present invention, it is possible to separate the backsheet from the waste solar module without heat treatment, and in the process of separating the backsheet, other components of the waste solar module may not be deformed or damaged.

The structure of the photovoltaic module is shown in FIG. 1 , and the description of the structure of the photovoltaic module is replaced with the above description.

FIG. 2 is a view showing a detailed structure of a back sheet constituting the solar module of FIG. 1 .

The back sheet 150 may include a transparent film layer 151 and a first coating layer 152 and a second coating layer 153 coated on the transparent film layer 151 . Since the back sheet 150 serves to protect the solar cell 110 from external impact, moisture, dust, etc., the transparent film layer 151 is made of a synthetic resin material having excellent durability and hydrolysis resistance, for example, PET. It may be formed mainly of (polyethylene terephthalate) material, and may further include a fluororesin such as PVF (polyvinyl fluoride) to supplement the performance of PET.

On the other hand, both surfaces of the transparent film layer 151 may be coated by the first coating layer 152 and the second coating layer 153 . The first coating layer 152 and the second coating layer 153 may be layers coated with TiO ₂ paste. In the structure of the solar module 100 according to the present invention, the first coating layer 152 may be a layer disposed between the second encapsulation layer 130 and one surface of the transparent film layer 151 , and the second coating layer 153 . is a layer disposed on the other surface of the transparent film layer 151 , and may correspond to the rear surface of the solar module 100 .

3 is a diagram illustrating a process of a method for separating a backsheet from a waste solar module according to the present invention.

The present invention relates to a method for separating the backsheet 150 from the waste solar module having the above-described structure, (a) preparing a mixed solvent containing N-methyl-2-pyrrolidone (NMP) (S100) , (b) heating the mixed solvent prepared in the step (S200), (c) immersing the waste solar module in the mixed solvent heated in the step (S300) and (d) the waste solar module It may include a step (S400) of recovering the separated back sheet.

According to the present invention, in the back sheet 150, when the waste solar module is immersed in the heated mixed solvent, the first and second coating layers 152 and 153 coated on the surface of the transparent film layer 151 are separated. It can be separated from the waste photovoltaic module as it becomes, thus it becomes possible to separate only the backsheet 150 without physical and chemical damage to other components of the waste photovoltaic module.

Specifically, in the waste photovoltaic module, the second coating layer 153 corresponding to the rear surface of the waste photovoltaic module in a state immersed in the heated mixed solvent may be separated first, and then the transparent film layer 151 and the second coating layer 153 The first coating layer 152 disposed between the second encapsulation layers 130 may be separated.

Hereinafter, each step of the method of separating the backsheet from the waste solar module will be described.

(a) preparing a mixed solvent containing N-methyl-2-pyrrolidone (NMP) (S100)

According to the present invention, a mixed solvent containing N-methyl-2-pyrrolidone (NMP) may be used to separate the backsheet 150 from the waste solar module. The first and second coating layers 152 and 153 coated with the TiO ₂ paste may be expanded by a mixed solvent including NMP to be separated from the waste solar module.

In the present invention, the mixed solvent containing NMP may be prepared by mixing the NMP solvent and toluene (TOL) or ethyl acetate (EA). Toluene and ethyl acetate have excellent permeability, and can prevent curling of the solar module when the backsheet is separated from the waste solar module in step (c).

In addition, the mixed solvent is NMP solvent and toluene or NMP solvent and ethyl acetate (EA) It can be prepared by mixing in a ratio of 7 to 3.

(b) a mixed solvent containing NMP (N-methyl-2-pyrrolidone) heating step (S200)

According to the present invention, the mixed solvent prepared in step (a) may be sealed and heated in a bath. In this step, the mixed solvent is preferably heated to a temperature of 60 to 80 ℃. The backsheet 150 may be naturally separated while being immersed in the mixed solvent of the above temperature range, and may not be separated below the above temperature range or may require physical force for separation.

(c) immersing the waste solar module in a mixed solvent containing heated NMP (N-methyl-2-pyrrolidone) (S300)

According to the present invention, in order to separate the backsheet 150 from the waste photovoltaic module, the mixed solvent heated to 60 to 80° C. in step (b) is placed in an immersion box, and then the waste photovoltaic module in the immersion box is placed in the immersion box for a predetermined time. can be immersed. The immersion step may be performed in a closed space, or may be performed in an exposed space. In this step, under the above-described concentration and temperature conditions of the mixed solvent, the waste photovoltaic module may be performed for 1 hour 30 minutes to 3 hours, and through this, the backsheet 150 may be completely separated from the waste photovoltaic module.

(d) recovering the back sheet separated from the waste solar module (S400)

When it is confirmed that the back sheet 150 is separated from the waste solar module, the back sheet 150 can be recovered from the immersion box. At this time, the recovered back sheet 150 may be in a state in which the first and second coating layers 152 and 153 have been removed, and the waste solar module from which the back sheet 150 is separated may also be recovered.

In the present invention, an experiment was conducted to confirm the effect of the temperature and concentration of the NMP solvent and the mixed solvent containing the NMP prepared above in separating the backsheet from the waste solar module.

Experimental Example 1: Evaluation of the effect of the temperature of the NMP solvent on the backsheet separation

300 ml of a 99.0% pure NMP solvent was put into a 500 ml sealed container. The amount of NMP solvent input was fixed, and after heating in a bath at 40°C, 60°C and 80°C, the waste solar module was immersed in a sealed container heated to each temperature.

The waste solar module immersed in the NMP solvent heated to 40 ° C., the physical change of the backsheet 150 started to occur after 5 hours. After the lapse of time, the second coating layer 153 became detachable in the form of a sheet, but physical force was required to separate it from the waste solar module. Even after 72 hours had elapsed, no change was observed in this state.

In the waste photovoltaic module immersed in NMP solvent heated to 60° C., the physical change of the backsheet 150 occurred after 1 hour had elapsed. When 1 hour had elapsed, the second coating layer 153 became separable in the form of a sheet, but physical force was required as in the case of the NMP solvent heated to 40° C. in a bath. When about 3 hours have elapsed, the first coating layer 152 became a detachable state in the form of a sheet, but physical force was required. Even after 72 hours had elapsed, no change was observed in this state.

On the other hand, in the waste solar module immersed in the NMP solvent heated to 80° C., the second coating layer 153 was naturally separated when 1 hour had elapsed. After 2 hours had elapsed, the first coating layer 152 started to be separated, but physical force was required. After 4 hours, the first coating layer 152 was naturally separated and the back sheet 150 was separated.

Part of the backsheet 150 separated at the above temperature was separated while maintaining the sheet shape, and part was separated in a torn shape. In this process, TiO ₂ constituting the coating layer was dissolved in the NMP solvent, resulting in turbidity of the solvent.

In addition, there was a problem in that the processing of the waste solar module was difficult due to the curling phenomenon of the waste solar module due to the high temperature. That is, it can be confirmed that the temperature change of the mixed solvent acts very sensitively in separating the backsheet from the waste solar module.

division Condition evaluation immersion time note 1h 2h 3h 4h 5h Temperature 40℃ separation
Whether x x x x 1 layer
separation physical force required 60℃ separation
Whether 1 layer
separation 1 layer
separation very
separation very
separation very
separation physical force required 70℃ separation
Whether 1 layer
separation 1 layer
separation very
separation very
separation very
separation nature
separation 80℃ separation
Whether 1 layer
separation very
separation very
separation very
separation very
separation nature
separation

(1 layer separation: separation of the second coating layer, complete separation: separation of the first and second coating layers)

Experimental Example 2: Evaluation of the effect of NMP solvent concentration on backsheet separation

According to Experimental Example 1, it was confirmed that the NMP solvent was effective in separating the backsheet when the solvent was heated to 80 °C in a bath.

This experiment was conducted to solve the turbidity of the NMP solvent and the curling phenomenon of the waste solar module.

In order to maintain the separation characteristics of the NMP solvent, distilled water was used to control the concentration. 300ml of NMP aqueous solution was put in a sealed container of 500ml. The bath temperature of the NMP aqueous solution was fixed at 80° C., where the backsheet separation effect was confirmed, and the amount of distilled water in the NMP aqueous solution was adjusted to 0%, 20%, and 40%. After immersing the waste solar module in each airtight container, the effect of separating the backsheet 150 as a predetermined time elapsed was compared.

In the case of the waste solar module in the sealed container containing the NMP aqueous solution containing 0% distilled water, the backsheet was naturally separated after 4 hours, but the NMP aqueous solution containing 20% distilled water and the NMP aqueous solution containing 40% distilled water The waste solar module in the sealed container was at a level where separation of the second coating layer 153 was possible only by physical force when 4 hours had elapsed.

In particular, in the case of the second coating layer 153 , the entire area is directly exposed to the NMP aqueous solution and it is confirmed that the NMP is affected, but in the case of the first coating layer 152 , between the transparent film layer 151 and the second encapsulation layer 130 . , the separation effect can occur only when NMP penetrates each interface.

When the NMP solvent is mixed with distilled water, it is confirmed that the water molecules have a relatively large size and thus impede penetration into the interface described above to separate the first coating layer 152. Therefore, when mixing the NMP solvent with distilled water It can be seen that the separation effect of the back sheet 150 is rapidly reduced even under the above temperature conditions.

division Condition evaluation immersion time note 1h 2h 3h 4h 5h NMP
density 100 separation
Whether 1 layer
separation very
separation very
separation very
separation very
separation nature
separation 80 separation
Whether change
none change
none change
none 1 layer
separation 1 layer
separation physical force required 60 separation
Whether change
none change
none change
none 1 layer
separation 1 layer
separation physical force required

(1 layer separation: separation of the second coating layer, complete separation: separation of the first and second coating layers)

Experimental Example 3: Evaluation of the Effect of NMP Mixed Solvent on Backsheet Separation

According to Experimental Example 1, it was confirmed that the NMP solvent was effective in separating the backsheet when the solvent was heated to 80 °C in a bath.

This experiment was conducted to solve the turbidity of the NMP solvent and the curling phenomenon of the waste solar module.

Through Experimental Example 2 conducted above, it was confirmed that, when distilled water was mixed with the NMP solvent, a result of reducing the backsheet separation effect was generated.

Therefore, in this experiment, the effect of the mixed solution prepared by mixing the NMP solvent with ethyl acetate (EA), toluene (TOL) and KOH having excellent permeability, respectively, on the backsheet separation was evaluated.

300ml of NMP aqueous solution was put in a sealed container of 500ml. The bath temperature of the NMP aqueous solution was fixed at 80 ° C, where the backsheet separation effect was confirmed, and the mixed solvent was mixed with 70% NMP, ethyl acetate (EA), toluene (TOL) and KOH by 30% each, and put in an airtight container. . After immersing the waste solar module in each airtight container, the effect of separating the backsheet 150 as a predetermined time elapsed was compared.

The results using a mixed solvent of NMP and KOH were similar to the results when NMP solvent was applied alone. The second coating layer 153 was naturally separated when 1 hour had elapsed after immersion, and the first coating layer 152 started to be separated in the form of a sheet from the time when 2 hours had elapsed after immersion, and was naturally separated after 4 hours. . However, in the case of KOH, the solar cell 110 was partially dissolved by penetrating between the front sheet 140 and the solar cell 110 in the waste solar module.

On the other hand, in the case of using a mixed solvent of NMP and EA, and a mixed solvent of NMP and TOL, the backsheet 150 naturally began to separate from the time point when 2 hours of the waste solar module immersed in the mixed solvent had elapsed. Compared with the result of natural separation of the backsheet 150 after 4 hours when NMP was used as the sole solvent, the separation effect of the backsheet 150 was maintained while the permeability of NMP in the mixed solvent was improved. confirmed to be In addition, in the case of the mixed solvent, as the reaction rate was increased, the time during which the waste solar module was exposed to a temperature of 80 °C decreased, so that curling did not occur.

On the other hand, in the case of the mixed solvent of NMP and TOL, the first and second coating layers 152 and 153 were completely separated in the form of a sheet, so that turbidity of the solvent did not appear, and it was confirmed that it was reusable.

division Condition evaluation immersion time note 1h 2h 3h 4h 5h ratio menstruum mix
menstruum 7:3 NMP
Exclusive separation
Whether 1 layer
separation very
separation very
separation very
separation very
separation curling
phenomenon KOH
including separation
Whether 1 layer
separation very
separation very
separation very
separation very
separation curling
phenomenon EA
including separation
Whether 1 layer
separation very
separation very
separation very
separation very
separation menstruum
muddiness TOL
including separation
Whether 1 layer
separation very
separation very
separation very
separation very
separation none

(1 layer separation: separation of the second coating layer, complete separation: separation of the first and second coating layers)

In the present invention, since the backsheet is naturally separated from the mixed solvent containing NMP, it is possible to separate the backsheet from the waste photovoltaic module without modifying or damaging other components of the waste photovoltaic module. In addition, the present invention can separate the back sheet from the waste solar module regardless of whether the tempered glass forming the front sheet is damaged.

In the above, preferred embodiments of the present invention have been described, but the present invention is not limited to the above-described embodiments and experimental examples, and various changes and modifications may be made within the scope without departing from the technical spirit of the present invention.

Claims (9)

In the method of separating the back sheet from a waste solar module comprising a solar cell, an encapsulant covering the upper and lower portions of the solar cell, and a front sheet and a back sheet covering the encapsulant,
(a) preparing a mixed solvent containing NMP (N-methyl-2-pyrrolidone);
(b) heating the prepared mixed solvent;
(c) immersing the waste solar module in the heated mixed solvent; and
(d) recovering the separated backsheet from the waste photovoltaic module, characterized in that it comprises the step of separating the backsheet from the waste photovoltaic module. According to claim 1,
The back sheet, a transparent film layer;
a first coating layer disposed between the encapsulation layer and one surface of the transparent film layer; and
A first coating layer disposed on the other surface of the transparent film layer,
Method for separating the backsheet from the waste solar module, characterized in that the first coating layer and the second coating layer are separated in step (c). 3. The method of claim 2,
In the step (c), the method of separating the backsheet from the waste solar module, characterized in that the first coating layer is separated after the second coating layer is separated. 3. The method of claim 2,
The first coating layer and the second coating layer, TiO ₂ A method of separating a backsheet from a waste solar module, characterized in that it is a layer coated with a paste. According to claim 1,
The mixed solvent of step (a) is a method of separating a backsheet from a waste solar module, characterized in that it is prepared by mixing toluene in NMP (N-methyl-2-pyrrolidone) solvent. According to claim 1,
The mixed solvent of step (a) is a method of separating a backsheet from a waste solar module, characterized in that it is prepared by mixing ethyl acetate (EA) in NMP (N-methyl-2-pyrrolidone) solvent. 7. The method according to claim 5 or 6,
The mixed solvent is prepared by mixing NMP (N-methyl-2-pyrrolidone) solvent and toluene or NMP (N-methyl-2-pyrrolidone) solvent and ethyl acetate (EA) in a ratio of 7 to 3 A method of separating the backsheet from the waste solar module. According to claim 1,
In the step (b), the method for separating the backsheet from the waste solar module, characterized in that heating the mixed solvent to 60 ℃ to 80 ℃. According to claim 1,
The step (c), characterized in that it proceeds for 1 hour 30 minutes to 3 hours, a method of separating the backsheet from the waste solar module.

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