KR100666093B1 - Method for Retrieving PET and EVA from Laminating Film - Google Patents

Abstract

The present invention relates to a method for recovering PET and EVA from a laminating film in which an EVA layer is laminated on a PET layer. In particular, the PET layer and the EVA layer are separated from the PET layer and the EVA layer in a short time using a hydrogen peroxide solution that is used as an oxidizing agent and has a pollution-free property. And a method for recovering the EVA.

The recovery method of the present invention includes a pulverizing step of pulverizing a laminate film using a pulverizer to form a pulverized product, a precipitation step of precipitating the pulverized product in a sedimentation tank containing hydrogen peroxide for a predetermined time, and obtaining the pulverized product from the sedimentation tank. The punching step of injecting and hitting with an erection, and a separating step of putting the pulverized product discharged from the punching machine into a sedimentation tank and separating and letting out the EVA suspended in the upper layer and the PET precipitated in the lower layer due to the specific gravity difference. It characterized in that it comprises a dehydration step of dehydrating EVA and PET.

Hydrogen peroxide, PET, EVA, Recovery method

Description

Method for recovering ethylene vinyl acetate copolymer and polyethylene terephthalate from waste laminating film composed of ethylene vinyl acetate copolymer and polyethylene terephthalate

1 is a schematic block diagram of an apparatus implementing the recovery method of the present invention.

2 is a schematic cross-sectional view of the punching machine shown in FIG. 1.

3 is a schematic cross-sectional view of the sedimentation tank shown in FIG.

4 is a flow chart of a recovery method according to an embodiment of the present invention.

5 is a flow chart of a recovery method according to another embodiment of the present invention.

The present invention relates to a method for recovering PET and EVA from a laminating film in which an EVA layer is laminated on a PET layer. In particular, the PET layer and the EVA layer are separated from the PET layer and the EVA layer in a short time using a hydrogen peroxide solution that is used as an oxidizing agent and has a pollution-free property. And a method for recovering the EVA.

Laminated film with EVA layer laminated on PET layer is formed by thermally compressing EVA film on PET film or by melt-coating EVA resin.It is widely used for coating film, printing material or label because of its excellent properties. It has been pointed out that it is not economical in terms of recycling of resources because it is not being discarded, and above all, it has been pointed out that the problem of environmental pollution caused by waste film and the loss of social cost due to it are large.

The object of the present invention is the PET layer and EVA layer in a short time through the precipitating step of pulverizing the laminate film and then pulverizing the pulverized product in the sedimentation tank containing hydrogen peroxide solution and the punching step to strike the pulverized product by using a punching machine to promote peeling. It is to provide a method for peeling off and recovering.

The present invention is implemented by the embodiment having the following configuration in order to achieve the above object.

According to a first embodiment of the present invention, the recovery method of the present invention, a pulverization step of forming a pulverized product by pulverizing the laminate film using a pulverizer, and a precipitation step of precipitating the pulverized product in a precipitation tank in which hydrogen peroxide is stored for a predetermined time And, the punching step of injecting the crushed product from the sedimentation tank into the crusher, and the crushed product discharged from the crusher into the sedimentation separation tank and the PET precipitated in the upper layer and the EVA suspended in the lower layer due to the specific gravity difference Separation step to separate and discharge, characterized in that it comprises a dehydration step of dewatering the separated EVA and PET.

According to a second embodiment of the present invention, in the recovery method of the present invention, in the first embodiment, the separating step further includes a washing step, wherein the washing step is a crushed water discharged from the punching machine It is characterized by consisting of being precipitated in the precipitation separation tank containing.

According to a third embodiment of the present invention, in the recovery method of the present invention, in the second embodiment, the punching step includes a first punching step by a primary punching machine and a second punching step by a secondary punching machine. It is characterized by.

According to a fourth embodiment of the present invention, the recovery method of the present invention, in the third embodiment, characterized in that the dehydration step consists of a PET dehydration step to dehydrate the PET, and EVA dehydration step to wash the EVA. .

According to a fifth embodiment of the present invention, the recovery method of the present invention, in the fourth embodiment, the PET punching step and the PET hitting the PET is introduced into the PET punching machine between the separating step and the PET dehydration step It is characterized in that it further comprises a PET precipitation step of precipitating the PET outflow from the erection in the PET precipitation tank to peel off the residual EVA.

Applicants will now describe the above embodiments in detail with reference to the accompanying drawings.

4 to 5, the recovery method of the present invention, the grinding step (S1), the precipitation step (S2), punching step (S3), separation step (S4), PET dehydration step (S6) largely , EVA dehydration step (S8), PET storage step (S7) and consists of EVA storage step (S9).

The crushing step (S3) is a step of forming a pulverized product of a predetermined size by putting the waste laminate film laminated EVA layer on the PET layer in a known crusher 100 and finely pulverized. In the above crushing step, the pulverized product is formed at the same time as the crushed product is hit during the crushing process, cracks are generated, and the hydrogen peroxide solution described below can penetrate between the cracks, thereby enabling the peeling of the PET layer and the EVA layer. do.

The precipitation step (S2) is a step of first peeling the PET layer and the EVA layer by leaving the pulverized product in the pulverized product precipitate tank 102 in which the hydrogen peroxide solution is stored for a predetermined time. Hydrogen peroxide solution is stored in the pulverized precipitate settlement tank 102, and when the pulverized substance is put into the pulverized precipitate settlement tank, the hydrogen peroxide solution penetrates between cracks formed in the pulverized substance. Hydrogen peroxide promotes decomposition when it comes into contact with organics, and generates heat of decomposition with oxygen as shown in the following reaction formula.

H ₂ O _2- > H ₂ 0 + 1 / 2O ₂ + 23.45Kcal

Oxygen gas generated here oxidizes the PET layer and the EVA layer, and decomposition heat weakens the adhesion between the PET layer and the EVA layer, thereby peeling off the PET and EVA. Generally, 35% hydrogen peroxide solution is suitable, but 50% hydrogen peroxide solution may be used if necessary.

The punching step (S3) is a step to increase the peeling efficiency by putting the crushed product into the punching machine 104 shown in FIG. The punching machine 104 is composed of a hitting portion having a housing 5 and a screwing wing 4 circumferentially mounted on a shaft 3 directly connected to the motor M. There is an inlet 2 for inflow and an outlet 6 for outflow of crushed products, and an inlet 1 for inflow of water is provided. When the pulverized material flows into the inlet, the pulverized material is discharged by moving to the outlet 6 while being hit by the strike blades 4 attached to the rotating shaft 3 directly connected to the motor M. This series of processes promotes the separation of the PET layer and the EVA layer. As shown in FIG. 1 and FIG. 5, if necessary, a plurality of punching machines 104 and 106 may be configured in series to increase the efficiency of peeling.

In the separation step (S4), the pulverized product discharged from the punching machine (104, 106) is immersed in the sedimentation separation tank (108) in which water is stored, and the PET is precipitated to the bottom by using a specific gravity difference and the EVA is floated to the upper layer to separate each other. It's a step. The sedimentation separation tank 108 is composed of a sedimentation tank 30, EVA recovery portion 10, PET recovery portion 20 and the diaphragm 40, the sedimentation tank 30 contains water (32). The EVA recovery part 10 is installed in the tube 13 and the tube 13 and consists of a screw 12 directly connected to the motor M, and recovers the EVA 51 suspended in the upper layer by rotating the screw. To the outside of the sedimentation tank. In addition, the PET recovery unit 20 is also made of a pipe 23 and a screw 12 installed in the pipe 23 and directly connected to the motor M, and the PET deposited on the floor by rotating the screw ( 52) Collect and discharge to the outside. The diaphragm 40 is installed in a predetermined position of the upper layer of the sedimentation separation tank 30, as shown in Figure 3, the EVA floating in the upper layer flows to the edge of the sedimentation separation tank past the end of the EVA recovery portion (10) Blocks the increase of the recovery rate of EVA. In addition, although not shown, it is also possible to blow the EVA floating in the upper layer to the end of the EVA recovery portion 10 by a blow provided at one end of the upper layer of the sedimentation separation tank. Using the above sedimentation tank, EVA and PET can be separated and discharged. In addition, since the water is stored in the sedimentation tank, when the pulverized product is immersed in the sedimentation tank, the hydrogen peroxide on the pulverized product is automatically washed, so there is no need to use a separate washing device.

The PET dehydration step (S6) is a step of dehydrating the water of the PET surface recovered using the known PET dehydrator 114, the EVA dehydration step (S8) is the water of the EVA surface recovered using the EVA dehydrator 118 Dehydration step.

The PET storage step (S7) is a step of storing the dehydrated PET in the PET storage tank 116, the EVA storage step (S9) is a step of storing the dehydrated EVA in the EVA storage tank (120).

According to another embodiment of the present invention, a PET punching step (S51) and a PET precipitation step (S52) may be added between the separating step (S4) and the PET dehydration step (S6). This is to additionally peel off the EVA may remain in the PET separated in the separation step (S4). The PET punching step (S51) is a step of peeling the EVA by additionally putting the PET discharged from the sedimentation separator 108 into the PET punching machine (110, see Fig. 2) and PET precipitation step (S52) The PET discharged from the erection 110 is immersed in the PET settling tank 112 in which water is stored, and the EVA is suspended in the upper layer and the PET is precipitated to the bottom to discharge the PET to the PET dehydrator 114. Although not shown, PET sedimentation tank 112 may have a structure of a sedimentation separation tank shown in FIG. 3, or may have a configuration of only PET recovery portion without EVA recovery portion in the sedimentation separation tank.

Applicants to demonstrate the effects of the present invention by measuring the time required for peeling when using a hydrogen peroxide solution and when using water.

 Experimental condition

30HP grinder, cylindrical punching machine 1M in length and 0.45M in diameter, square mill settling tank 6M in length, 1M in height and 1.2M in width, sedimentation separation 6M in length, 2.2M in height and 1.2M in width Experiment using the bath according to the process shown in FIG. 4. In addition, when the amount of waste laminating film discharged without being separated from the total amount of waste laminating film added is expressed as a percentage, this is called a recovery rate, and the time required for recovery to be 90%, 70%, and 50% is water. And measure by dividing the case of 35% hydrogen peroxide solution. And even in the case of using 35% hydrogen peroxide solution, the recovery rate is reduced when the hydrogen peroxide solution is dissolved in the settling tank and the pulverized product is immediately precipitated (Test Examples 1 to 3), and when precipitated after a predetermined time has passed (Comparative Example 4). Each time is measured up to 70%.

Test Example 1

6 tons of waste laminating film is placed in a sedimentation tank containing 10 tons of 35% hydrogen peroxide solution and the recovery time reaches 90%. It takes about 8 hours.

Test Example 2

6 tons of the waste laminating film was placed in a sedimentation tank containing 10 tons of 35% hydrogen peroxide solution and the recovery time reached 70%.

Test Example 3

6 tons of the waste laminating film was placed in a sedimentation tank containing 10 tons of 35% hydrogen peroxide solution, and the recovery time reached 50%. It took about 5 hours.

Comparative Example 1

6 tons of waste laminating film was placed in a sedimentation tank containing 10 tons of water, and the recovery time reached 90%, but after 72 hours, it did not reach 90%.

Comparative Example 2

6 tons of waste laminating film was placed in a sedimentation tank containing 10 tons of water, and the recovery time reached 70%. However, it did not reach 70% even after 72 hours.

Comparative Example 3

6 tons of the waste laminating film was placed in a sedimentation tank containing 10 tons of water, and the time required for the recovery to reach 50% was approximately 24 hours.

Comparative Example 4

After 10 tons of 35% hydrogen peroxide solution was dissolved in the settling tank and flowed for 7 hours, 6 tons of waste laminating film was added to measure the time taken for the recovery to reach 70%, which took approximately 9 hours.

In the comparative examples 1 to 3 and Comparative Examples 1 to 3, the recovery rate in Comparative Examples 1 to 2 using water did not reach 90%, 70%, and compared to Comparative Example 3 having a recovery rate of 50%. In the case of Test Examples 1 to 3 using a hydrogen peroxide solution, it was confirmed that the peeling time can be significantly reduced.

In addition, comparing Test Example 2 with Comparative Example 4, when the hydrogen peroxide solution in the settling tank and put the waste laminating film after a predetermined time, it was confirmed that the peeling time is significantly increased compared to Test Example 2, which is hydrogen peroxide in the atmosphere Since the generator generates oxygen and heat of decomposition at the time of exposure, it seems that the hydrogen peroxide oxidizes and the amount of heat of decomposition decreases after a certain time since exposure.

Applicants have described the embodiments of the present invention, but various modifications and variations of the present invention should also be construed as falling within the scope of the present invention as long as the technical spirit of the present invention is embodied.

The present invention has the following effects by the above configuration.

The recovery method of the present invention is economically advantageous in that it can efficiently recycle the waste laminating film that is discarded by peeling the laminating film composed of the PET layer and the EVA layer using hydrogen peroxide solution and the punching step in a short time, and environmental pollution The problem can be solved together.

Since the recovery method of the present invention uses a hydrogen peroxide solution having pollution-free characteristics, it is possible to obtain an effect of reducing the problem of environmental pollution in the wastewater treatment step after use.

Claims (5)

A pulverizing step of pulverizing the laminate film using a pulverizer to form a pulverized product, and a precipitation step of precipitating the pulverized product in a pulverized precipitate settling tank in which hydrogen peroxide is stored so as to first peel the PET layer and the EVA layer, The punching step of injecting and crushing the pulverized product from the crushing tank, and putting the pulverized product discharged from the crusher into the sedimentation separation tank and separating and discharging the PET suspended in the upper layer and the PET precipitated in the lower layer due to the specific gravity difference. And a dehydration step of dehydrating the separated EVA and PET. The method of claim 1, wherein the separating step further comprises a washing step, wherein the washing step is characterized in that the pulverized product discharged from the punching machine is precipitated in a sedimentation separation tank containing water. The recovery method according to claim 2, wherein the punching step comprises a first punching step by a first punching machine and a second punching step by a second punching machine. 4. The method of claim 3, wherein the dehydration step comprises a PET dehydration step of dehydrating PET and an EVA dehydration step of dehydrating EVA. 5. The PET precipitation step of claim 4, wherein the PET punching step of injecting PET into the PET punching machine and the PET spilled from the PET punching machine are separated from the PET punching tank between the separation step and the PET dehydration step to separate the residual EVA. Recovery method characterized in that it further comprises a step.

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