Separation and recovery solution for pet film and application thereof

Abstract

The application provides a separation and recovery solution for PET film and application thereof, and relates to the technical field of PET material recovery. The separation and recovery solution for PET film provided by the application contains, in terms of 100% by weight, raw material components: 1-5% of alkaline substances, 3-10% of organic solvents, 0.5-2% of surfactants, 0.1-0.5% of cationic flocculants, 2-8% of gas generating materials, and the balance of water; the gas generating materials can generate gas at 50-100 DEG C. The degumming rate is improved by adding the gas generating materials, and the tackiness of the adhesive is reduced by adding the cationic flocculants.

Description

Technical Field

[0001] This invention belongs to the field of PET material recycling technology, and relates to a separation and recycling solution for PET membranes and its application. Background Technology

[0002] One application of PET material is as an insulating protective film (PET film) to protect devices or similar objects. Before use, the insulating protective film typically consists of an insulating protective film, an adhesive layer, and a release film. Due to the presence of the adhesive layer, recycling the PET material from waste insulating protective films or production scraps requires overcoming the adhesive layer's bonding effect. The adhesive layer is mainly made of acrylic ester, and it is generally decomposed and broken down using an alkaline solution, allowing the adhesive layer to detach from the insulating protective film and thus obtain a high-purity insulating protective film. Chinese patent CN112706503A discloses a composition for the separation and recycling of PET composite films, comprising 4-12% sodium hydroxide, 8-30% dichloromethane, 2-10% alcohol, and the balance being water; it may also include 1-5% sodium diisobutylnaphthalenesulfonate, 4-5% sodium dodecylbenzeneiodate, or 3-5% ethylene glycol butyl ether. However, in practical applications, it has been found that the soaking time required in this existing technology is too long, generally 10 hours or longer. Furthermore, the degraded and detached adhesive fragments are easily adsorbed and remain on the PET film. The alkali resistance of PET film is generally poor, especially for polyester PET materials. Soaking in alkaline solutions for too long will cause the PET film to degrade. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a separation and recovery solution for PET membranes and its application.

[0004] The technical solution of the present invention is as follows:

[0005] A separation and recovery solution for PET membranes, by 100% weight, comprises: 1-5% alkaline substances, 3-10% organic solvents, 0.5-2% surfactants, 0.1-0.5% cationic flocculants, 2-8% gas-generating materials, and the balance being water; The gas-generating material can generate gas at 50-100°C.

[0006] Preferably, the alkaline substance is selected from one or more of sodium hydroxide, potassium hydroxide, and tetramethylammonium hydroxide.

[0007] Preferably, the solubility of the organic solvent in water at 20°C is not less than 3 g / L; The organic solvent has a boiling point at 1 atmosphere that exceeds the temperature at which the gas-generating material produces gas.

[0008] More preferably, the organic solvent is selected from one or more of ethylene glycol phenyl ether, ethanol, isopropanol, butyl acetate, ethyl acetate, tetrahydrofuran, N-methylpyrrolidone, benzyl alcohol, ethylene glycol monomethyl ether, acetone, diethylene glycol dimethyl ether, propylene glycol monomethyl ether, and diethylene glycol monobutyl ether.

[0009] Preferably, the surfactant is selected from nonionic surfactants; The nonionic surfactant is selected from one or more of fatty alcohol polyoxyethylene ethers, alkylphenol polyoxyethylene ethers, fatty acid polyoxyethylene esters, polyether surfactants, alkyl polysaccharide glycoside surfactants, organosilicon nonionic surfactants, and organofluorine nonionic surfactants.

[0010] Preferably, the cationic flocculant is selected from cationic polymeric flocculants; The cationic polymeric flocculant is selected from one or more of polyacrylamide and its copolymers, polyethyleneimine, and chitosan quaternary ammonium salts.

[0011] Preferably, the gas-generating material is selected from one or more of the following: bicarbonate, a combination of a first ammonium salt / sodium bicarbonate, a combination of a second ammonium salt / sodium nitrite, and a combination of a third ammonium salt / calcium hydroxide.

[0012] More preferably, the bicarbonate is selected from one or more of sodium bicarbonate, ammonium bicarbonate and potassium bicarbonate; The first ammonium salt, the second ammonium salt, and the third ammonium salt are individually selected from ammonium chloride and / or ammonium sulfate.

[0013] More preferably, in the combination of the first ammonium salt and sodium bicarbonate, the molar ratio of the first ammonium salt to the sodium bicarbonate is 1:2-2:1; In the combination of the second ammonium salt and sodium nitrite, the molar ratio of the second ammonium salt to the sodium nitrite is 1:2-2:1; In the combination of the third ammonium salt and calcium hydroxide, the molar ratio of the third ammonium salt to the calcium hydroxide is 1:1 to 4:1.

[0014] An application of the separation and recovery solution described in any of the above embodiments for the separation and recovery of PET films containing adhesives.

[0015] The beneficial effects of this invention are as follows: In this invention, a cationic flocculant and a gas-generating material are added to the separation and recovery solution. After penetrating the adhesive layer, the gas-generating material generates gas upon heating, causing the adhesive to expand and form numerous gaps. This facilitates the continuous penetration of the separation and recovery solution and rapidly decomposes the adhesive. The cationic flocculant can adsorb the decomposed adhesive fragments and form precipitates, preventing the adhesive fragments from re-adsorbing onto the surface of the PET film. Therefore, the separation and recovery solution of this invention, used for the separation and recovery of PET films containing adhesives, can accelerate the separation of adhesives and prevent adhesive fragments from re-adsorbing onto the surface of the PET film. Attached Figure Description

[0016] Figure 1 The appearance of the blue film.

[0017] Figure 2 This shows the appearance of the blue film after it has been perforated.

[0018] Figure 3 The PET film after separation and recycling in Example 1. Detailed Implementation

[0019] The technical solution of the present invention will be further explained and described below through specific embodiments.

[0020] To address the problems of difficult separation, long processing time, and incomplete recovery of PET films containing adhesives (especially acrylic adhesives), this invention proposes a separation and recovery solution for PET films. By weight, the raw material components include: 1-5% alkaline substances, 3-10% organic solvents, 0.5-2% surfactants, 0.1-0.5% cationic flocculants, 2-8% gas-generating materials, and the balance being water. Gas-generating materials can produce gas at 50-100℃.

[0021] This invention contains a gas-generating material and a cationic flocculant in the separation and recovery solution. The solution gradually penetrates into the interface (adhesive interface) between the PET film and the adhesive layer. The gas-generating material, when heated, produces gas and expands, creating pores at the adhesive interface. These pores accelerate the penetration of the separation and recovery solution into the adhesive interface, thus forming a virtuous cycle. The gas-generating material's gas production and pore formation further accelerate the penetration of the separation and recovery solution into the adhesive interface, and the penetration of the solution further accelerates the formation of pores at the adhesive interface, even causing adhesive degradation and detachment. Therefore, the separation and recovery solution of this invention can significantly accelerate the recovery of PET film, with a short separation and recovery time, and the recovered PET film can still maintain a good condition.

[0022] Gas-generating materials can produce gas at 50-100℃. This gas-generating material can produce gas through its own decomposition or by the reaction of two or more materials. It is relatively stable at room temperature and does not or hardly produces gas. If the content of the gas-generating material is too low, or if gas production is too rapid and complete, the gas-generating effect will be weakened, leading to a decrease in the separation and recovery efficiency of the PET membrane. For example, the weight content of the gas-generating material can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, etc.

[0023] In some embodiments, the alkaline substance is selected from one or more of sodium hydroxide, potassium hydroxide, and tetramethylammonium hydroxide, which are strong bases and have a good decomposition effect on acrylic adhesives.

[0024] In some embodiments, the solubility of the organic solvent in water at 20°C is not less than 3 g / L; The boiling point of the organic solvent at 1 atmosphere is higher than the temperature at which the gas-generating material produces gas.

[0025] Organic solvents help improve the permeability of the separation and recovery solution and the swelling of the adhesive, reduce the bonding strength at the bonding interface, further enhance the permeability of the separation and recovery solution, and at the same time, the swollen adhesive is more easily decomposed by alkaline substances.

[0026] The boiling point of the organic solvent is higher than the temperature at which the gas-generating material produces gas, which can avoid excessive volatilization of the organic solvent when heating to produce gas.

[0027] In some embodiments, the organic solvent is selected from one or more of ethylene glycol phenyl ether, ethanol, isopropanol, butyl acetate, ethyl acetate, tetrahydrofuran, N-methylpyrrolidone, benzyl alcohol, ethylene glycol monomethyl ether, acetone, diethylene glycol dimethyl ether, propylene glycol monomethyl ether, and diethylene glycol monobutyl ether.

[0028] In some embodiments, the surfactant is selected from nonionic surfactants; Nonionic surfactants are selected from one or more of the following: fatty alcohol polyoxyethylene ethers (such as AEO-3, AEO-9, AEO-12, etc.), alkylphenol polyoxyethylene ethers (such as NPEO, OPEO, DPEO, DNPEO, etc.), fatty acid polyoxyethylene esters (such as LAE-9, emulsifier A-100), polyether surfactants (such as PPO-PEO-PPO), alkyl polysaccharide glycoside surfactants, organosilicon nonionic surfactants (such as polyether-modified silicone oil, with high surface activity and low surface tension), and organofluorine nonionic surfactants (with low surface tension and high surface activity). Surfactants can be obtained directly from the market.

[0029] Nonionic surfactants are insensitive to both anionic and cationic environments and do not affect the role of cationic flocculants in the separation and recovery solution. Nonionic surfactants can reduce the surface tension of the separation and recovery solution, improve the wetting and penetration ability of the bonding interface, and also have certain emulsifying properties, which can emulsify and disperse detached adhesive fragments. They can also solubilize organic solvents with insufficient solubility.

[0030] In some embodiments, the cationic flocculant is selected from cationic polymeric flocculants; Cationic polymeric flocculants are selected from one or more of polyacrylamide and its copolymers, polyethyleneimine, and chitosan quaternary ammonium salts. Fragments produced by the decomposition of acrylic adhesives carry a negative charge and, although they can be emulsified and dispersed by surfactants, may still adsorb onto PET films. Cationic flocculants carry a positive charge and can adsorb acrylic adhesive fragments through electrostatic interactions, forming large flocculent particles that deposit in the treatment system and are easily separated, for example, by simple filtration. Cationic flocculants are commercially available.

[0031] In some embodiments, the gas-generating material is selected from one or more of bicarbonate, a combination of a first ammonium salt / sodium bicarbonate, a combination of a second ammonium salt / sodium nitrite, and a combination of a third ammonium salt / calcium hydroxide. Bicarbonate can decompose upon heating to produce carbon dioxide gas. The combinations of the first ammonium salt / sodium bicarbonate, the second ammonium salt / sodium nitrite, and the third ammonium salt / calcium hydroxide can react upon heating to produce gas.

[0032] In some embodiments, the bicarbonate is selected from one or more of sodium bicarbonate, ammonium bicarbonate and potassium bicarbonate; The first ammonium salt, the second ammonium salt, and the third ammonium salt are individually selected from ammonium chloride and / or ammonium sulfate.

[0033] In some embodiments, the molar ratio of the first ammonium salt to sodium bicarbonate in the first ammonium salt / sodium bicarbonate combination is 1:2-2:1. For example, the molar ratio can be 1:2, 2:3, 1:1, 3:2, 2:1, etc. The ammonium ions in the first ammonium salt react with the bicarbonate ions in the sodium bicarbonate in a molar ratio of 1:1 and decompose to produce ammonia and carbon dioxide. In the combination of second ammonium salt and sodium nitrite, the molar ratio of second ammonium salt to sodium nitrite is 1:2-2:1. For example, the molar ratio can be 1:2, 2:3, 1:1, 3:2, 2:1, etc. The ammonium ions in the second ammonium salt react with the nitrite ions in the sodium nitrite in a molar ratio of 1:1 and decompose to produce nitrogen gas. In the combination of tertiary ammonium salt and calcium hydroxide, the molar ratio of tertiary ammonium salt to calcium hydroxide is 1:1 to 4:1. For example, the molar ratio can be 1:1, 3:2, 2:1, 3:1, 4:1, etc. The ammonium ions in the tertiary ammonium salt react with the hydroxide ions in the calcium hydroxide in a molar ratio of 1:1 and decompose to produce ammonia gas.

[0034] In this invention, when preparing the separation and recovery solution, an alkaline substance and a portion of water can be used to prepare a first solution, a cationic flocculant, a surfactant, and a portion of water can be used to prepare a second solution, and a gas-generating material, an organic solvent, and the remaining water can be used to prepare a third solution. The first, second, and third solutions can be mixed before use.

[0035] When the gas-generating material consists of two materials (such as a second ammonium salt and sodium nitrite), the alkaline substance, sodium nitrite and some water can be used to make a first solution, the cationic flocculant, surfactant and some water can be used to make a second solution, and the second ammonium salt, organic solvent and remaining water can be used to make a third solution. The first solution, the second solution and the third solution can be mixed before use.

[0036] On the other hand, the present invention also proposes an application of the separation and recovery solution described in any of the above embodiments for the separation and recovery of PET films containing adhesives. The separation and recovery solution of the present invention can quickly decompose the adhesive on the PET film and prevent the decomposed adhesive fragments from being re-adsorbed onto the PET film. To accelerate the penetration of the separation and recovery solution into the bonding interface, multiple small holes can be punched in the PET film, the holes penetrating the adhesive layer, or the PET film can be rubbed, folded, or subjected to other operations to reduce the bonding strength of the bonding interface.

[0037] The technical solution of the present invention will be further described and illustrated below with reference to various embodiments. Unless otherwise specified, the parts mentioned in the following embodiments are parts by weight.

[0038] Example 1 The separation and recovery solution for PET membranes, by weight, comprises the following raw material components: 5% sodium hydroxide, 8% anhydrous ethanol, 1.2% surfactant AEO-3, 0.5% polyacrylamide cationic flocculant, 5% gas-generating material, and the balance being water. The gas-generating material consists of ammonium chloride and sodium nitrite in a molar ratio of 1:1, and can decompose to produce nitrogen gas at 70-90℃.

[0039] Sodium hydroxide, sodium nitrite, and 30% water are mixed to obtain the first solution; polyacrylamide cationic flocculant, AEO-3, and 30% water are mixed to obtain the second solution; and ammonium chloride, anhydrous ethanol, and the remaining water are mixed to obtain the third solution.

[0040] Example 2 The difference between this embodiment and Embodiment 1 is that in Embodiment 1, the content of the gas-generating material was adjusted from 5% to 2%, and the amount of water was increased accordingly. The remaining steps remain unchanged.

[0041] Example 3 The difference between this embodiment and Embodiment 1 is that in Embodiment 1, the content of the gas-generating material was adjusted from 5% to 8%, and the amount of water was reduced accordingly. The remaining steps remain unchanged.

[0042] Example 4 The difference between this embodiment and Embodiment 1 is that in Embodiment 1, the gas-generating material was changed to an equal weight of ammonium bicarbonate, which was added to the third solution. The remaining steps remained unchanged.

[0043] Example 5 The difference between this embodiment and Embodiment 1 is that in Embodiment 1, the content of polyacrylamide cationic flocculant was adjusted from 0.5% to 0.1%, and the amount of water was increased accordingly. The remaining steps remain unchanged.

[0044] Example 6 The difference between this embodiment and Embodiment 1 is that in Embodiment 1, the sodium hydroxide content was adjusted from 5% to 1%, and the amount of water was increased accordingly. The remaining steps remain unchanged.

[0045] Example 7 The difference between this embodiment and Embodiment 1 is that in Embodiment 1, the 1.2% surfactant AEO-3 was changed to 0.5% surfactant LAE-9, and the amount of water was increased accordingly. The remaining steps remain unchanged.

[0046] Comparative Example 1 The difference between this comparative example and Example 1 is that in Example 1, the gas-generating material was changed from 5% to 0%, and the amount of water was increased accordingly. The remaining steps remained unchanged. That is, no gas-generating material was added in this comparative example.

[0047] Comparative Example 2 The difference between this comparative example and Example 1 is that in Example 1, no cationic polyacrylamide flocculant was added, and the amount of water was increased accordingly. The remaining steps remained unchanged. That is, no cationic polyacrylamide flocculant was added in this comparative example.

[0048] Performance testing Select two PET films of the same size. Each PET film has an acrylic adhesive layer. The two PET films are bonded together with the adhesive to form a set of blue films (appearance as shown in the attached image). Figure 1 (As shown).

[0049] Each set of blue membranes has the same number of small holes punched through it (as shown in the attached image). Figure 2(As shown). The first and second solutions of the separation and recovery solution to be tested were mixed, and then the blue membrane to be tested was added. The mixture was stirred at room temperature for 5 minutes, and then the third solution was added. The stirring was continued and the temperature was raised to 80°C (in Example 4, ammonium bicarbonate was used, and the temperature was raised to 60°C). The time for the two PET membranes in a set of blue membranes to completely separate (degumming time) and the number of PET membranes with adhesive residue (residual adhesive) after separation were observed. Ten sets of blue membranes were placed in each separation and recovery solution to be tested. The shorter the degumming time, the faster the degumming speed; the more re-adhesive membranes, the easier it is for adhesive fragments to be re-adsorbed onto the surface of the PET membrane.

[0050] Example 1: The appearance of the PET film after degumming is shown in the attached figure. Figure 3 As shown, there is no adhesive residue on the surface.

[0051] The results are shown in Table 1 below.

[0052] Table 1

[0053] Therefore, as can be seen from the data results in Table 1 above, the present invention can quickly achieve the separation and recycling of PET film, the added gas-generating material can significantly accelerate the degumming speed, and the added cationic flocculant can significantly reduce the residual adhesive caused by the re-adhesion of adhesive fragments.

[0054] As described above, the basic principles, main features, and advantages of the present invention have been shown and described. Those skilled in the art should understand that the present invention is not limited to the above embodiments, which are merely preferred embodiments and should not be construed as limiting the scope of the invention. All equivalent changes and modifications made in accordance with the scope of the patent and the description should still fall within the scope of the present invention. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A separation and recovery solution for PET membranes, characterized in that, By weight, the raw material composition includes: 1-5% alkaline substances, 3-10% organic solvents, 0.5-2% surfactants, 0.1-0.5% cationic flocculants, 2-8% gas-generating materials, and the balance being water; The gas-generating material can generate gas at 50-100°C.

2. The separation and recovery solution for PET membranes according to claim 1, characterized in that, The alkaline substance is selected from one or more of sodium hydroxide, potassium hydroxide, and tetramethylammonium hydroxide.

3. The separation and recovery solution for PET membranes according to claim 1, characterized in that, The solubility of the organic solvent in water at 20°C is not less than 3 g / L; The organic solvent has a boiling point at 1 atmosphere that exceeds the temperature at which the gas-generating material produces gas.

4. The separation and recovery solution for PET membranes according to claim 3, characterized in that, The organic solvent is selected from one or more of ethylene glycol phenyl ether, ethanol, isopropanol, butyl acetate, ethyl acetate, tetrahydrofuran, N-methylpyrrolidone, benzyl alcohol, ethylene glycol monomethyl ether, acetone, diethylene glycol dimethyl ether, propylene glycol monomethyl ether, and diethylene glycol monobutyl ether.

5. The separation and recovery solution for PET membranes according to claim 1, characterized in that, The surfactant is selected from nonionic surfactants; The nonionic surfactant is selected from one or more of fatty alcohol polyoxyethylene ethers, alkylphenol polyoxyethylene ethers, fatty acid polyoxyethylene esters, polyether surfactants, alkyl polysaccharide glycoside surfactants, organosilicon nonionic surfactants, and organofluorine nonionic surfactants.

6. The separation and recovery solution for PET membranes according to claim 1, characterized in that, The cationic flocculant is selected from cationic polymeric flocculants; The cationic polymeric flocculant is selected from one or more of polyacrylamide and its copolymers, polyethyleneimine, and chitosan quaternary ammonium salts.

7. The separation and recovery solution for PET membranes according to claim 1, characterized in that, The gas-generating material is selected from one or more of the following: bicarbonate, a combination of a first ammonium salt / sodium bicarbonate, a combination of a second ammonium salt / sodium nitrite, and a combination of a third ammonium salt / calcium hydroxide.

8. The separation and recovery solution for PET membranes according to claim 7, characterized in that, The bicarbonate is selected from one or more of sodium bicarbonate, ammonium bicarbonate and potassium bicarbonate; The first ammonium salt, the second ammonium salt, and the third ammonium salt are individually selected from ammonium chloride and / or ammonium sulfate.

9. The separation and recovery solution for PET membranes according to claim 7, characterized in that, In the first ammonium salt / sodium bicarbonate combination, the molar ratio of the first ammonium salt to the sodium bicarbonate is 1:2-2:1; In the combination of the second ammonium salt and sodium nitrite, the molar ratio of the second ammonium salt to the sodium nitrite is 1:2-2:1; In the combination of the third ammonium salt and calcium hydroxide, the molar ratio of the third ammonium salt to the calcium hydroxide is 1:1 to 4:

1.

10. An application of the separation and recovery solution according to any one of claims 1-9, characterized in that, Separation and recycling of PET films containing adhesives.

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