Method for grading, classifying, recycling and resource recycling of PCB photosensitive dry film residues

Abstract

The invention provides a method for graded and classified recycling and resource recycling of PCB photosensitive dry film residues, and belongs to the technical field of chemical treatment and classified recycling of solid hazardous waste. The method comprises the following steps: S1, uniformly mixing PCB photosensitive dry film residues with a water-soluble organic solvent, and then filtering to obtain super-crosslinked film residue powder and a first extracting solution; s2, uniformly mixing the first extracting solution with a strong alkaline solution, and extracting to obtain an organic phase containing an initiator system and an alkaline water phase; s3, standing and separating the alkaline water phase to obtain an adhesive and a second extracting solution; s4, adjusting the pH value of the second extracting solution to be acidic, and then filtering to obtain flocculent solid and a clarified water phase; and S5, carrying out recycling and resource utilization on the corresponding separated substances. According to the method, the initiator system, polymethyl methacrylate and the copolymer adhesive in the original dry film waste residues are separated out, the high-quality activated carbon is prepared, the production process is simple, the solvent can be recycled, the cost is low, and secondary pollution is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical treatment and classified recycling of solid hazardous wastes, and particularly relates to a method for hierarchical classification recycling and resource-based circular utilization of PCB photosensitive dry film residues. Background Art

[0002] The photosensitive material in printed circuit boards / integrated circuits (PCBs), namely photosensitive dry film, is the core component of photoresist and a key material in the semiconductor industry, playing an irreplaceable role in multiple fields such as aerospace technology, computers, medical equipment, consumer electronics, and automotive electronics.

[0003] During the production process of printed circuit boards, organic dry films and wet films are mainly used as anti-electroplating resistors or anti-etching resistors. After electroplating or etching is completed, the organic film resistors are generally removed using NaOH solution, so waste residues such as developed dry film residues and stripped dry film residues are generated. The film residues generated after dry film removal are strongly alkaline and have a high COD (chemical oxygen demand), containing resin and a large amount of organic matter. The film residues are in a semi-solid state with a water content as high as 60% - 100%. Dry film residues belong to the HW13 sub-item in the list of hazardous wastes and have no economic value. They are all transported by HW13 qualified manufacturers to incineration plants for incineration treatment, resulting in secondary pollution.

[0004] During the natural drying process, due to the adhesiveness and poor water permeability of the waste film residues, some of the water inside the film residues still cannot volatilize. And currently, the most common treatment method for waste film residues is through high-temperature incineration. However, due to the strong corrosiveness and poor combustibility of the film residues, the treatment cost of the film residues has increased significantly. Moreover, with the continuous strengthening of environmental protection efforts, the treatment volume of such waste is also relatively limited. Therefore, the treatment of waste film residues has become a problem that still needs to be solved in the development of waste-producing enterprises and disposal industries.

[0005] Therefore, there is an urgent need for an environmentally friendly, high-value, and low-cost hazardous waste treatment technology for PCB waste film residues that does not require dehydration, uses a small amount of solvent, and can be hierarchically classified and recycled. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for hierarchical classification recycling and resource-based circular utilization of PCB photosensitive dry film residues. The present invention separates the initiator system, the main component of the dry film, polymethyl methacrylate (PMMA), and the copolymer from the original dry film waste residues and prepares high-quality activated carbon. It does not require the high energy required for incineration and does not require an external metal catalyst, which can greatly improve the environmental pollution problem caused by incineration. The production process of the present invention is simple, with low cost, and does not produce secondary pollution.

[0007] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0008] The present invention provides a method for hierarchical classification recycling and resource-based circular utilization of PCB photosensitive dry film waste residues, comprising the following steps:

[0009] S1. Mix the PCB photosensitive dry film waste residues with a water-soluble organic solvent evenly and then filter to obtain hypercrosslinked polyester film waste powder and a first extract; this step separates the insoluble hypercrosslinked polyester by using the principles of solvent swelling and dissolution.

[0010] S2. Mix the first extract with a strong alkaline solution evenly and then perform extraction to obtain an organic phase containing an initiator system and an alkaline aqueous phase; this step separates the small molecule initiator system by using the principle of solvent extraction, enabling the initiator to dissolve in the organic phase.

[0011] S3. Let the alkaline aqueous phase stand for separation to obtain a lower-layer viscous solid and a second extract, and filter to separate and obtain an adhesive sample.

[0012] S4. Adjust the pH of the second extract to acidic and then filter to obtain a flocculent solid and a clarified aqueous phase; this step precipitates polymethyl methacrylate under acidic conditions to obtain polyester powder.

[0013] S5. Recycle and resourcefully utilize the corresponding separated substances; adopt various resource utilization methods according to requirements.

[0014] Preferably, the mass ratio of the PCB photosensitive dry film waste residues to the water-soluble organic solvent in S1 is 1:(5 - 10).

[0015] Preferably, the water-soluble organic solvent is one of methanol, ethanol, acetone, tetrahydrofuran, and acetonitrile.

[0016] Preferably, the mixing time in S1 is 5 - 10 h, and the mixing temperature is 20 - 30 °C.

[0017] Preferably, the volume ratio of the first extract to the strong alkaline solution in S2 is 100:(20 - 200).

[0018] Preferably, the strong alkaline solution includes but is not limited to one of aqueous sodium hydroxide solution and aqueous potassium hydroxide solution; the concentration of the strong alkaline solution is 0.5 - 1.5 wt%.

[0019] Preferably, the solvent used for extraction in S2 is one of dichloromethane, chloroform, dichloroethane, CCl 4 One of them.

[0020] Preferably, the standing time in S3 is 2 - 10 h.

[0021] Preferably, the pH is adjusted to 0.5 - 4 in S4.

[0022] Preferably, the pH regulator is HCl or H 2 2 SO 4 4 solution with a concentration of 0.1 - 5 mol / L.

[0023] Preferably, the corresponding isolates in S5 are recycled and reused in one or more of the following ways:

[0024] The hypercrosslinked membrane residue powder obtained from S1 is sintered to prepare high-quality carbon materials;

[0025] The organic phase containing the initiator system separated in S2 is obtained the initiator system by removing the solvent;

[0026] The adhesive obtained from S3 is dried to obtain an adhesive product;

[0027] The flocculent solid separated in S4 is dried to obtain polymethacrylate powder;

[0028] The clarified aqueous phase separated in S4 is concentrated under reduced pressure and dried to obtain crystal powder.

[0029] More preferably, the vacuum drying conditions in each step are: vacuum degree ≥ 0.06 Mpa, temperature ≥ 60 °C, and drying time ≥ 10 h.

[0030] More preferably, the sintering process of the hypercrosslinked membrane residue powder adopts a gradient heating method at 5 °C / min and stays at 700 °C, 800 °C, and 900 °C for 1 h each.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] After treating the PCB photosensitive dry film residue by the method of the present invention, the initiator system, the main component of the dry film polymethyl methacrylate (PMMA), copolymer, and high-quality activated carbon in the original dry film waste residue can be separated. Such a chemical treatment method does not require the high energy required for incineration, does not require an external metal catalyst, and can greatly improve the environmental pollution problem caused by incineration. The production process of the present invention is simple, with low cost and no secondary pollution. Description of the Drawings

[0033] Figure 1 1H-NMR spectrum of the initiator system separated and recovered in Example 1;

[0034] Figure 2 1H-NMR spectrum of the adhesive sample separated and recovered in Example 1;

[0035] Figure 3 FT-IR spectrum of the flocculent precipitate polyester sample separated and recovered in Example 1;

[0036] Figure 4 Raman spectrum of the high-quality activated carbon material prepared by separation in Example 1. Detailed Description of the Invention

[0037] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be construed as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0038] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0039] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0040] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of this application are only exemplary.

[0041] Regarding the use of "comprising", "including", "having", "containing", etc. herein, they are all open-ended terms, meaning including but not limited to.

[0042] As used in the present invention, "room temperature" and "normal temperature" are both calculated as 25 ± 2°C unless otherwise specified.

[0043] All raw materials used in the following examples of the present invention are obtained commercially.

[0044] The PCB waste film residue used in the following examples:

[0045] Example 1:

[0046] S1. Take 3 g of PCB waste film residue, pulverize it and place it in a beaker. Add 60 mL of methanol and stir at 25 °C for 5 h. Filter to obtain 0.7183 g of hypercrosslinked film residue powder and the first extraction solution;

[0047] Subject the hypercrosslinked film residue powder to sintering using a gradient temperature increase method, with a heating rate of 5 °C / min, and hold for 1 h at 700 °C, 800 °C, and 900 °C respectively to obtain a high-quality activated carbon material;

[0048] S2. Add 30 mL of 1 wt% sodium hydroxide solution to the first extraction solution and mix well. Place the mixed solution in a separatory funnel and perform extraction and separation with dichloromethane to obtain an organic phase and an alkaline aqueous phase. Subject the organic phase to a reduced pressure concentration step to obtain 0.2410 g of an initiator system, and at the same time recover the organic solvent.

[0049] S3. Let the alkaline aqueous phase stand for 5 h to separate out the adhesive and the upper clear and transparent solution (the second extraction solution);

[0050] S4. Add 3 mol / L HCl solution to the second extraction solution to adjust the acidity to pH = 1.75, and perform centrifugal separation to obtain a flocculent precipitate and a transparent solution.

[0051] S5. Subject the centrifuged transparent solution to reduced pressure concentration to obtain a salt compound.

[0052] Control the vacuum temperature of the separated gel and flocculent precipitate at 80 °C and keep it dry for 12 h. After drying, discharge the material to obtain 0.2650 g of purple polymethacrylic acid gel and 0.1045 g of resin powder.

[0053] Detect the separated and recovered substances as shown in Figures 1-4 .

[0054] Example 2:

[0055] S1. Take 3 g of PCB waste film residue, pulverize it and place it in a beaker. Add 60 mL of ethanol and stir at 20 °C for 10 h. Filter to obtain 0.7037 g of hypercrosslinked film residue powder and the first extraction solution;

[0056] Subject the hypercrosslinked film residue powder to sintering using a gradient temperature increase method, with a heating rate of 5 °C / min, and hold for 1 h at 700 °C, 800 °C, and 900 °C respectively to obtain a high-quality activated carbon material;

[0057] S2. Add 60 mL of 0.5 wt% sodium hydroxide solution to the first extraction solution and mix well. Place the mixed solution in a separatory funnel and perform extraction and separation with chloroform to obtain an organic phase and an alkaline aqueous phase. Subject the organic phase to a reduced pressure concentration step to obtain 0.2336 g of an initiator system, and at the same time recover the organic solvent.

[0058] S3. Leave the alkaline aqueous phase to stand for 2 h to separate the adhesive and the upper clear and transparent solution (the second extract).

[0059] S4. Add 0.1 mol / L HCl solution to the second extract to adjust the acidity to pH = 4, and obtain a flocculent precipitate and a transparent solution by centrifugal separation.

[0060] S5. Subject the centrifuged transparent solution to vacuum concentration to obtain a salt compound.

[0061] Control the vacuum temperature of the separated gel and flocculent precipitate at 80 °C and keep drying for 12 h. After drying, discharge the material to obtain 0.3925 g of purple polymethacrylic acid gel and 0.1163 g of resin powder.

[0062] Example 3:

[0063] S1. Take 3 g of PCB waste film residue, crush it and place it in a beaker, add 60 mL of acetone, stir at 30 °C for 5 h, and filter to obtain 0.8534 g of hypercrosslinked film residue powder and the first extract;

[0064] Subject the hypercrosslinked film residue powder to sintering by a gradient heating method, with a heating rate of 5 °C / min, and stay at 700 °C, 800 °C, and 900 °C for 1 h each to obtain a high-quality activated carbon material;

[0065] S2. Add 120 mL of 1.5 wt% sodium hydroxide solution to the first extract and mix evenly. Place the mixed solution in a separatory funnel, and separate the organic phase and the alkaline aqueous phase by extraction with dichloroethane. Subject the organic phase to vacuum concentration to obtain 0.3161 g of an initiator system, and recover the organic solvent at the same time.

[0066] S3. Leave the alkaline aqueous phase to stand for 10 h to separate the adhesive and the upper clear and transparent solution (the second extract);

[0067] S4. Add 5 mol / L HCl solution to the second extract to adjust the acidity to pH = 0.5, and obtain a flocculent precipitate and a transparent solution by centrifugal separation.

[0068] S5. Subject the centrifuged transparent solution to vacuum concentration to obtain a salt compound.

[0069] Control the vacuum temperature of the separated gel and flocculent precipitate at 80 °C and keep drying for 12 h. After drying, discharge the material to obtain 0.7463 g of purple polymethacrylic acid gel and 0.3247 g of resin powder.

[0070] Test example

[0071] The product detection in the separation or recovery preparation in Example 1 is as follows Figures 1 to 4 As shown, it shows that the separation and recovery method of the present invention can separate and recycle various substances in the PCB photosensitive dry film waste; at the same time, this method uses less solvent and can be recycled.

[0072] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and retouches can be made, and these improvements and retouches should also be regarded as the protection scope of the present invention.

Claims

1. A method for recycling and reusing PCB photosensitive dry film residue by classification and classification, characterized in that: The following steps are involved: S1. The PCB photosensitive dry film residue is mixed evenly with a water-soluble organic solvent and then filtered to obtain a super-crosslinked film residue powder and a first extract; S2. The first extract is mixed with a strong alkaline solution and then extracted to obtain an organic phase containing an initiator system and an alkaline aqueous phase; S3. The alkaline aqueous phase is allowed to stand for separation to obtain an adhesive and a second extract; S4. The pH of the second extract is adjusted to acidic and then filtered to obtain a flocculent solid and a clear aqueous phase; S5. Recycle the corresponding separated materials for resource utilization.

2. The method according to claim 1, characterized in that The mass ratio of the PCB photosensitive dry film residue to the water-soluble organic solvent in S1 is 1:(5-10).

3. The method according to claim 2, characterized in that The water-soluble organic solvent is one of methanol, ethanol, acetone, tetrahydrofuran and acetonitrile.

4. The method according to claim 1, characterized in that: The mixing time in S1 is 5 to 10 hours, and the mixing temperature is 20 to 30°C.

5. The method according to claim 1, characterized in that The volume ratio of the first extracting solution to the strong alkaline solution in S2 is 100:(20-200).

6. The method according to claim 5, characterized in that The strong alkaline solution includes but is not limited to one of a sodium hydroxide aqueous solution and a potassium hydroxide aqueous solution; the concentration of the strong alkaline solution is 0.5-1.5 wt %.

7. The method according to claim 1, characterized in that The solvent used for the extraction in S2 is one of dichloromethane, chloroform, dichloroethane and CCl4.

8. The method according to claim 1, characterized in that The pH in S4 is adjusted to 0.5-4.

9. The method according to claim 8, characterized in that The pH regulator is 0.1-5 mol / L HCl or H2SO4 solution.

10. The method according to claim 1, characterized in that The corresponding separated materials in S5 are recycled and utilized as resources in one or more of the following ways: The super-crosslinked film slag powder obtained in S1 is sintered to prepare high-quality carbon material; The organic phase containing the initiator system separated in S2 is subjected to solvent removal to obtain the initiator system; The adhesive obtained in S3 is dried to obtain an adhesive product; The flocculent solid separated in S4 is dried to obtain polymethacrylate powder; The clarified aqueous phase separated in S4 is concentrated under reduced pressure and dried to obtain sodium chloride crystal powder.

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