TWI843459B - Method for separating glue-like ethylene-co-vinyl acetate (eva) layers and substrate of soak-treated waste photovoltaic (pv) under specific wet conditions - Google Patents

Abstract

The present invention relates to a method for separating glue-like ethylene-co-vinyl acetate (EVA) layers and a substrate of a soak-treated solar photovoltaic (PV) under specific wet conditions. Primarily, the method comprises steps of putting a broken PV panel into a container filled with an organic solvent, wherein the organic solvent is composed of at least two of heptane, hexane and methyl-ethyl-ketone (MEK), and then placing the container into an oscillator for a certain time of supersonic oscillation. With the aforesaid wet soaking technique, the EVA layer of the soak-treated PV panel will be subject to an area expansion for separation from the substrate of the PV panel, in order to effectively dismantling and recycling the PV panel. Meanwhile, the organic solvent used in the present invention is non-toxic and harmless to the environment and creatures, thus the present invention is designed to have no damaging effect on the environment.

Description

Method for separating the adhesive layer of discarded solar panels by wet immersion

The present invention relates to a method for separating the adhesive layer of waste solar panels by wet immersion, and in particular to a wet immersion separation technology for decomposing the EVA adhesive layer in the solar panel as its application invention.

With the development of energy decarbonization and emission reduction, solar power generation is currently the world's main renewable energy, which does not require fuel and can maintain environmental sustainability. However, solar panels are mainly a composite material structure formed by sandwiching two layers of ethylene vinyl acetate (EVA) between solar cell modules and encapsulating them with glass plates and insulating backplanes. But when its service life ends, it also derives the problem of recycling and disposal.

Today’s solar panel recycling methods are divided into thermal treatment, dry recycling and wet recycling, including:

(1) This heat treatment is often used to treat the EVA layer in solar panels. The EVA layer is thermally cracked or burned to separate the solar panels. However, the disadvantages are the energy consumed by the high temperature in this process, and the exhaust gas or metal elements in the exhaust gas generated during the combustion process diffuse with the high temperature gas.

(2) Dry recycling mainly involves dismantling and physically separating solar panels. However, the disadvantage is that the cost of recycling is not pure. The solution is often to remove them through wet recycling.

(3) Wet recycling uses chemical solutions to separate solar panels based on their chemical properties. However, the solvents currently used are all highly hazardous substances. In addition to being harmful to operators, the treated wastewater is also extremely environmentally unfriendly.

Therefore, how to deal with discarded solar panels is a very urgent issue at present. In order to find a solution that is relatively friendly to the environment and less harmful, recycling companies regard it as an extremely important research trend to completely dismantle solar panels and recycle the resources therein.

Therefore, the inventor has been adhering to the rich design development and actual manufacturing experience in the relevant industry for many years, and has continued to develop and research in the spirit of continuous improvement, and has provided a method for separating the adhesive layer of waste solar panels by wet immersion, in order to achieve the purpose of having better practical value.

The main purpose of the present invention is to provide a method for separating the adhesive layer of waste solar panels by wet immersion, and more particularly to provide a wet immersion separation technology for decomposing the EVA adhesive layer in the solar panel.

The main purpose and effect of the method for separating the adhesive layer of waste solar panels by wet immersion of the present invention are achieved by the following specific technical means:

The broken solar panels are mainly taken and placed in a container. The container is injected with an organic solvent for soaking. The organic solvent is a mixed solution of at least two kinds of heptane, hexane and butanone. Then it is placed in an oscillator and subjected to ultrasonic vibration for a certain time. Through this wet immersion method, the EVA glue layer can be expanded, which promotes the separation of the EVA glue layer and the substrate, effectively dismantling and recycling the resources therein. At the same time, the mixed solution is non-toxic and has little harm, is extremely friendly to the environment and has a perfect environmental protection concept.

The present invention provides a preferred embodiment of the method for separating the adhesive layer of waste solar panels by wet immersion, wherein the heptane, hexane and butanone solution selected in the organic solvent are mixed in a ratio of 1:1.

The present invention discloses a preferred embodiment of a method for separating the adhesive layer of waste solar panels by wet immersion, wherein the organic solvent is a mixed solution of butanone and heptane.

The present invention discloses a preferred embodiment of a method for separating the adhesive layer of waste solar panels by wet immersion, wherein the oscillator is set to perform ultrasonic oscillation at a power of 120W and a frequency of 40KHZ.

The present invention discloses a preferred embodiment of a method for separating the adhesive layer of waste solar panels by wet immersion, wherein the medium inside the oscillator is water or ionized water.

In order to make the technical content, purpose of the invention and the effects achieved by the present invention more complete and clear, they are described in detail below, and please refer to the disclosed drawings and figure numbers:

First, the actual application technology and means of the present invention are shown in the first figure, which is a schematic diagram of the structure of the method for separating the glue layer of waste solar panels by wet immersion. The steps are as follows:

S1) placing the broken solar panel (1) in a container (3) filled with an organic solvent (2) for soaking, wherein the organic solvent (2) is a mixed solution of at least two of heptane, hexane and butanone;

S2) The container (3) is placed in an oscillator (4), a medium (5) is injected into the oscillator (4), and ultrasonic vibration is applied for a certain period of time to make the EVA rubber layer on the solar panel expand and separate.

However, the organic solvent (2) of the present invention uses three solutions of heptane, hexane and butanone, and at least two of them are mixed. Therefore, mixed solutions of different combinations can be derived. The performance of these mixed solutions can be further demonstrated by the following specific examples, which do not intend to limit the scope of the present invention in any form.

When it is actually implemented, step (S1) is first executed, in which the broken solar panel (1) is obtained to be soaked in an organic solvent (2). However, in order to understand the soaking results of different organic mixed solutions, the area of the broken solar panel (1) must be calculated in advance in the experimental process to compare the area before soaking with the area after soaking and vibration. The area is calculated using the Heron formula as follows:

The lengths of the four sides are A, B, C, and D;

The area of the quadrilateral is equal to

In this way, the area of each solar panel (1) can be known to facilitate subsequent experimental calculations. Then, the solar panel (1) is immersed in an organic solvent (2). During the experiment, heptane, hexane, and butanone are divided into three experimental groups: a butanone-hexane mixed solution, a butanone-heptane mixed solution, and a hexane-heptane mixed solution. During the immersion time, an ultrasonic oscillator (4) is used to oscillate the panel. The power is set to 1. 20W, frequency 40KHZ, and the medium (5) [water or ionized water is used here] in the ultrasonic oscillator (4) is replaced every half hour, and the amount of water used for each oscillation is 500ml. The initial water temperature is about 20℃. After oscillating for 30 minutes, the water temperature rises by about 30℃. Every 30 minutes, take out the solar panel (1) sample to measure the length of the four sides, and calculate the area and expansion ratio.

(I) Experimental group of butanone-hexane mixed solution: this experiment mixed butanone solution with hexane solution in a ratio of 1:1, and used 10 samples for the experiment. The experimental data obtained are as follows: Before shock Four side lengths Sample number thickness Side length Side length Side length Side length Area Expansion ratio Corresponding to the last ratio No. 1 0.05 1.85 1.15 1.15 1 1.522734357 No. 2 0.05 1.15 1.1 1 0.7 0.947301884 No. 3 0.05 1.25 1.2 0.8 0.8 0.979521367 No. 4 0.05 1.2 1.05 1.1 1 1.177068492 No. 5 0.05 1 1 1 0.9 0.948811757 No. 6 0.05 1 1 1 1 1 No. 7 0.05 1.1 1.05 1 1 1.07466401 No. 8 0.05 1.15 1.05 1.1 1.1 1.208749354 No. 9 0.05 1.25 1.2 1 0.9 1.162377514 No. 10 0.05 1.4 1.3 1.3 1.25 1.719631024 Shock 30 minutes Four side lengths Area Expansion ratio Corresponding to the last ratio No. 1 0.05 1.8 1.5 1.5 1.3 2.292480916 1.505502851 No. 2 0.05 1.5 1.5 1.35 0.5 1.33064232 1.404665548 No. 3 0.05 1.7 1.5 1.2 1 1.749285568 1.785857488 No. 4 0.05 1.75 1.55 1.5 1.1 2.122875408 1.803527512 No. 5 0.05 1.5 1.5 1.5 1.4 2.173791331 2.291067027 No. 6 0.05 1.5 1.4 1.3 1.2 1.809972375 1.809972375 No. 7 0.05 1.6 1.5 1.4 1.25 2.049883286 1.907464348 No. 8 0.05 1.7 1.5 1.5 1.45 2.354282584 1.947701214 No. 9 0.05 1.65 1.45 1.4 1.4 2.164457207 1.862094871 No. 10 0.05 1.4 1.3 1.3 1.25 1.719631024 1 Shock 60 minutes Four side lengths Area Expansion ratio Corresponding to the last ratio No. 1 0.05 2.3 2.15 1.95 1.8 4.166167303 2.735977739 1.817318205 No. 2 0.05 1.8 1.7 1.5 1.1 2.258421739 2.384057054 1.697241779 No. 3 0.05 2 1.7 1.6 1.3 2.659323222 2.714921094 1.5202339 No. 4 0.05 1.9 1.5 1.7 1.7 2.869930313 2.438201628 1.351907088 No. 5 0.05 1.7 1.9 1.7 1.7 3.054701295 3.219501943 1.405241272 No. 6 0.05 1.8 1.7 1.65 1.55 2.797489946 2.797489946 1.545598145 No. 7 0.05 1.85 1.8 1.7 1.6 3.009774117 2.800665221 1.46826609 No. 8 0.05 2 1.85 1.65 1.55 3.075576356 2.544428542 1.306375189 No. 9 0.05 2.2 2 1.9 1.7 3.769880635 3.243249796 1.74172103 No. 10 0.05 1.9 1.75 1.65 1.5 2.868688725 1.668200146 1.668200146 Shock 90 minutes Four side lengths Area Expansion ratio Corresponding to the last ratio No. 1 0.05 2.25 2.1 1.9 1.65 3.850801865 2.528873041 0.924303223 No. 2 0.05 1.8 1.65 1.6 1.15 2.348110943 2.478735641 1.039713222 No. 3 0.05 2.25 1.8 1.6 1.3 2.89271546 2.953192811 1.087763772 No. 4 0.05 2.1 1.9 1.65 1.5 3.141433229 2.668861881 1.094602616 No. 5 0.05 1.8 1.8 1.8 1.65 3.102303517 3.269672297 1.015583266 No. 6 0.05 1.9 1.8 1.8 1.7 3.234996136 3.234996136 1.156392408 No. 7 0.05 1.9 1.8 1.7 1.6 3.049983607 2.838081092 1.013359637 No. 8 0.05 2.3 1.9 1.7 1.7 3.545208033 2.932955474 1.152697128 No. 9 0.05 1.9 1.85 1.6 1.5 2.904838569 2.499049177 0.770538606 No. 10 0.05 1.8 1.6 1.6 1.6 2.714682302 1.578642316 0.946314697 Shock 120 minutes Four side lengths Area Expansion ratio Corresponding to the last ratio No. 1 0.05 2.45 2.1 2 1.7 4.180760201 2.74556109 1.085685618 No. 2 0.05 2 1.9 1.55 1.15 2.61682059 2.762393524 1.114436521 No. 3 0.05 2.15 1.85 1.6 1.3 2.87631709 2.936451603 0.99433115 No. 4 0.05 2 1.65 1.6 1.5 2.809607888 2.386953612 0.894371353 No. 5 0.05 1.7 1.65 1.65 1.6 2.721249713 2.868060701 0.877170689 No. 6 0.05 1.8 1.8 1.7 1.6 2.968853946 2.968853946 0.917730291 No. 7 0.05 2 1.9 1.8 1.8 3.508645572 3.26487678 1.150381781 No. 8 0.05 2.3 2 1.8 1.6 3.636804057 3.00873299 1.025836572 No. 9 0.05 2.1 2 1.9 1.7 3.684184951 3.169525311 1.268292493 No. 10 0.05 1.9 1.7 1.7 1.6 2.963396489 1.723274614 1.091618156

Please refer to the second figure, (a) represents the state after 30 minutes of vibration, (b) represents the state after 60 minutes of vibration, (c) represents the state after 90 minutes of vibration, and (d) represents the state after 120 minutes of vibration. Based on the above experimental data, it is calculated that the EVA rubber layer area of the solar panel (1) treated with a mixture of butanone and hexane and then vibrated has a good expansion ratio. Please refer to the curve diagram in the third figure and the following table: Immersion in butanone-hexane mixed solution and shaking time (minutes) EVA rubber layer area expansion ratio 0 min 1.00 30 min 1.73 60 min 2.65 90 min 2.70 120 min 2.78

(II) Experimental group of butanone-heptane mixed solution: this experiment mixed butanone solution with heptane solution in a ratio of 1:1, and used 5 samples for the experiment. The experimental data obtained are as follows: Before shock Four side lengths Sample number thickness Side length Side length Side length Side length Area Expansion ratio Corresponding to the last ratio No. 1 0.05 1.3 1.2 1 0.8 1.119662337 No. 2 0.05 1.2 1.2 1.1 0.9 1.195826074 No. 3 0.05 0.95 0.9 0.9 0.9 0.832178757 No. 4 0.05 1.2 1.15 1.1 1 1.232283037 No. 5 0.05 1.4 1.2 1 0.5 0.948258272 Shock 30 minutes Four side lengths Area Expansion ratio Corresponding to the last ratio No. 1 0.05 1.6 1.2 1.2 1.1 1.58445377 1.415117502 No. 2 0.05 2 1.5 1.2 1.2 2.053921554 1.717575489 No. 3 0.05 1.4 1.2 1.1 1 1.357790024 1.631608608 No. 4 0.05 1.5 1.5 1.5 1.4 2.173791331 1.764035749 No. 5 0.05 2 1.2 1.1 0.5 1.088852607 1.148265868 Shock 60 minutes Four side lengths Area Expansion ratio Corresponding to the last ratio No. 1 0.05 2.1 1.9 1.7 1.6 3.292904303 2.940979787 2.078258366 No. 2 0.05 2.1 2.1 1.7 1.5 3.356188314 2.806585662 1.634039191 No. 3 0.05 1.6 1.5 1.5 1.4 2.244994432 2.697731001 1.653417975 No. 4 0.05 2 1.9 1.7 1.6 3.214965008 2.608950144 1.478966708 No. 5 0.05 2.5 2.4 1.8 0.9 3.248999846 3.426281576 2.983874792 Shock 90 minutes Four side lengths Area Expansion ratio Corresponding to the last ratio No. 1 0.05 2.15 2.1 1.9 1.5 3.596075498 3.211749987 1.092068025 No. 2 0.05 2.15 2 1.8 1.7 3.626860245 3.032932901 1.080648612 No. 3 0.05 1.7 1.6 1.5 1.5 2.473624618 2.972467869 1.101839979 No. 4 0.05 2 2 1.9 1.6 3.490142368 2.832257089 1.085592646 No. 5 0.05 2.75 2.2 2 1.6 4.388302589 4.627750392 1.350662603 Shock 120 minutes Four side lengths Area Expansion ratio Corresponding to the last ratio No. 1 0.05 2 2 1.7 1.5 3.195997497 2.85442976 0.88874594 No. 2 0.05 2.15 2.1 1.75 1.7 3.664986357 3.064815558 1.010512154 No. 3 0.05 1.7 1.7 1.5 1.4 2.463933593 2.960822504 0.996082257 No. 4 0.05 2.2 2 2 1.95 4.1418866 3.361148758 1.186738581 No. 5 0.05 2.6 2.3 1.9 1.1 3.607515592 3.80435974 0.822075397

Please refer to the fourth figure, (a) represents the state after 30 minutes of vibration, (b) represents the state after 60 minutes of vibration, (c) represents the state after 90 minutes of vibration, and (d) represents the state after 120 minutes of vibration. Based on the above experimental data, it is calculated that the EVA rubber layer area expansion ratio of the solar panel (1) treated with a mixture of butanone and heptane solution and vibration is better than that of the mixture of butanone and hexane solution, and when soaked for 90 minutes, the expansion ratio is as high as 3.33. Please refer to the curve diagram of the fifth figure and the following table: Immersion in butanone-hexane mixed solution and shaking time (minutes) EVA rubber layer area expansion ratio 0 min 1.00 30 min 1.53 60 min 2.89 90 min 3.33 120 min 3.21

(III) Hexane-heptane mixed solution test group: This test mixed the hexane solution at a ratio of 1:heptane solution 1, and used 5 samples for the test. The experimental data obtained are as follows: Before shock Four side lengths Sample number thickness Side length Side length Side length Side length Area Expansion ratio Corresponding to the last ratio No. 1 0.05 1.15 1.15 1.1 1 1.206358156 No. 2 0.05 1.2 1.2 1 1 1.2 No. 3 0.05 1.2 1.1 1 0.9 1.089954127 No. 4 0.05 1 1 0.9 0.9 0.9 No. 5 0.05 1.15 1.1 0.95 0.9 1.039987981 Shock 30 minutes Four side lengths Area Expansion ratio Corresponding to the last ratio No. 1 0.05 1.3 1.25 1.1 1.05 1.369990876 1.135641906 No. 2 0.05 1.3 1.2 1.2 1 1.369176303 1.140980253 No. 3 0.05 1.4 1.2 1.2 1.05 1.454284484 1.334262101 No. 4 0.05 1.15 1.15 1.05 1 1.178471434 1.309412705 No. 5 0.05 1.25 1.2 1.05 1 1.25499004 1.206735138 Shock 60 minutes Four side lengths Area Expansion ratio Corresponding to the last ratio No. 1 0.05 1.85 1.25 1.25 1.15 1.8 1.492094194 1.313877363 No. 2 0.05 1.8 1.5 1.45 1.25 2.209637979 1.841364983 1.613844743 No. 3 0.05 1.7 1.4 1.2 1.15 1.806113641 1.657054729 1.241925951 No. 4 0.05 1.5 1.4 1.4 1.3 1.954993606 2.172215118 1.658923202 No. 5 0.05 1.5 1.45 1.3 1.3 1.9171454 1.843430343 1.52761802 Shock 90 minutes Four side lengths Area Expansion ratio Corresponding to the last ratio No. 1 0.05 1.5 1.4 1.35 1.2 1.844855071 1.529276411 1.024919484 No. 2 0.05 1.9 1.65 1.5 1.4 2.563151061 2.135959217 1.159986878 No. 3 0.05 2.1 1.8 1.75 1.7 3.35073307 3.074196414 1.855217188 No. 4 0.05 1.75 1.7 1.5 1.5 2.5871406 2.874600667 1.323349904 No. 5 0.05 1.8 1.7 1.5 1.4 2.534955621 2.437485498 1.322255277 Shock 120 minutes Four side lengths Area Expansion ratio Corresponding to the last ratio No. 1 0.05 1.9 1.8 1.8 1.4 2.941214673 2.438094076 1.594279528 No. 2 0.05 1.8 1.7 1.6 1.5 2.70998155 2.258317958 1.057285149 No. 3 0.05 1.7 1.7 1.5 1.2 2.28604872 2.097380672 0.682253308 No. 4 0.05 1.8 1.7 1.5 1.4 2.534955621 2.816617357 0.97982909 No. 5 0.05 1.7 1.7 1.5 1.3 2.375878785 2.284525234 0.937246698

Please refer to the sixth figure, (a) represents the state after 30 minutes of vibration, (b) represents the state after 60 minutes of vibration, (c) represents the state after 90 minutes of vibration, and (d) represents the state after 120 minutes of vibration. Based on the above experimental data, it is calculated that the EVA rubber layer area of the solar panel (1) treated with a mixed solution of hexane and heptane and then vibrated has a good expansion ratio. Please refer to the curve diagram of the seventh figure and the following table: Immersion in butanone-hexane mixed solution and shaking time (minutes) EVA rubber layer area expansion ratio 0 min 1.00 30 min 1.22 60 min 1.80 90 min 2.41 120 min 2.38

In summary, the adhesive layer separation method of the present invention includes two parts: organic solvent immersion and ultrasonic vibration heat treatment. In this process, the present invention immerses the solar panel (1) (photovoltaic module) in an organic solvent such as heptane, hexane, butanone, etc. to dissolve the EVA adhesive layer and recover the tempered glass; and in the heat treatment process of the vibration device (4), the present invention removes the EVA adhesive layer remaining on the solar panel (1) and can fully recover the tempered glass. However, no matter the solar panel (photovoltaic module) is immersed in a butanone-hexane mixed solution, a butanone-heptane mixed solution or a hexane-heptane mixed solution, the EVA adhesive layer has a good expansion rate, especially after being immersed in the butanone-heptane mixed solution for 90 minutes, the expansion rate is as high as 3.33, which can effectively promote the separation of the EVA adhesive layer from the substrate (tempered glass), effectively dismantle and recycle the resources therein. In addition, the organic solvent (2) and heat treatment of the adhesive layer separation method of the present invention can not only effectively recycle the solar panel module, but also the mixed solution of the organic solvent is non-toxic and has little hazard, is extremely friendly to the environment and has a perfect environmental protection concept, and is more conducive to the environment and human health.

However, the aforementioned embodiments or drawings do not limit the product structure or usage of the present invention. Any appropriate changes or modifications by a person having ordinary knowledge in the relevant technical field should be deemed to be within the patent scope of the present invention.

In summary, the embodiments of the present invention can achieve the expected effects, and the specific structure disclosed therein has not been seen in similar products, nor has it been disclosed before the application. It fully complies with the provisions and requirements of the Patent Law. Therefore, an application for an invention patent is filed in accordance with the law, and we sincerely request your review and grant of the patent. We would be grateful for your kindness.

1: Solar panels

2: Organic solvents

3: Container

4: Oscillator

5: Medium

Figure 1: Schematic diagram of the present invention

FIG. 2 : Schematic diagram of the solar panel of the present invention immersed in a mixture of butanone and hexane for (a) immersion and vibration for 30 minutes, (b) immersion and vibration for 60 minutes, (c) immersion and vibration for 90 minutes, and (d) immersion and vibration for 120 minutes.

Figure 3: A diagram showing the expansion ratio of butanone to hexane of the present invention.

FIG. 4 : Schematic diagram of the solar panel of the present invention immersed in a mixture of butanone and heptane for (a) immersion and vibration for 30 minutes, (b) immersion and vibration for 60 minutes, (c) immersion and vibration for 90 minutes, and (d) immersion and vibration for 120 minutes.

Figure 5: a diagram showing the expansion ratio of butanone to heptane of the present invention.

Figure 6: Schematic diagram of the solar panel of the present invention immersed in a hexane-heptane mixed solution for (a) immersion and vibration for 30 minutes, (b) immersion and vibration for 60 minutes, (c) immersion and vibration for 90 minutes, and (d) immersion and vibration for 120 minutes.

Figure 7: Hexane-heptane expansion ratio diagram of the present invention.

1: Solar panels

2: Organic solvents

3:Container

4: Oscillator

5: Medium

Claims (5)

A method for separating the adhesive layer of waste solar panels by wet immersion, the steps are as follows: S1) Place the broken solar panels in a container filled with an organic solvent for immersion, and the organic solvent is a mixed solution of at least two of heptane, hexane, and butanone; S2) Place the container in an oscillator, inject a medium into the oscillator, and apply ultrasonic vibration for a certain time to make the EVA adhesive layer on the solar panel expand and separate. As described in claim 1, the method for separating the adhesive layer of waste solar panels by wet immersion, wherein the heptane, hexane and butanone solution selected in the organic solvent are mixed in a ratio of 1:1. A method for separating the adhesive layer of waste solar panels by wet immersion as described in claim 1, wherein the organic solvent is a mixed solution of butanone and heptane. A method for separating the adhesive layer of waste solar panels by wet immersion as described in claim 1, wherein the oscillator is set to a power of 120W and a frequency of 40KHZ for ultrasonic oscillation. The method for separating the adhesive layer of waste solar panels by wet immersion as described in claim 1, wherein the medium inside the oscillator is water.