Method for preparing regenerated resin from pet recyclate and use thereof

Abstract

The present invention relates to the technical field of plastic recycling, and disclosed are a method for preparing a regenerated resin from PET recyclate and a use thereof. The method comprises the following steps: mixing PET recyclate, a polyol, and a catalyst; carrying out elevated temperature reaction; after cooling, adding a polybasic acid or a polybasic acid anhydride for reaction; and after the reaction is finished, cooling to obtain a regenerated resin. The polyol is selected from at least one of diethylene glycol, tripropylene glycol, and polyethylene glycol; the average functionality of the polybasic acid is greater than 2; and the catalyst is selected from at least two of zinc acetate, manganese acetate, and tetrabutyl titanate. According to the present invention, the regenerated resin is applied to the preparation of water-based ink, so that the water-based ink achieves the same printing performance as acrylic resin ink. In the method of the present invention, no waste is generated during polymerization, achieving a 100% recycling rate for waste plastic. Fossil raw materials are saved, and PET recyclate is also fully utilized, achieving the objective of turning waste into wealth.

Description

A method for preparing recycled resin from PET recycled material and its application Technical Field

[0001] The invention belongs to the technical field of plastic recycling, and in particular relates to a method for preparing recycled resin from PET recycled material and application thereof. Background Art

[0002] In recent years, the market for PET (polyethylene terephthalate) recycled materials has shown a positive growth trend. With the increasing attention and promotion of environmental protection and sustainable development, PET recycled materials are increasingly becoming the raw material of choice in industries such as consumer packaging and textiles.

[0003] The production cost of PET recycled materials is relatively low, while also reducing the need for new raw materials, saving energy, and lowering carbon emissions, all in line with environmental protection. While some literature has mentioned the use of recycled PET in adhesives and inks, there have been no reports of its direct use in water-based inks.

[0004] Environmentally friendly water-based packaging and printing inks primarily use water-based polyacrylic resins as the binder, with a small amount of high-end inks using polyurethane as a linker. Both polyacrylic resins and polyurethanes require petrochemical raw materials to be produced through polymerization reactions. The production process consumes energy and petrochemical raw materials, generating a certain amount of polluting waste. Consequently, existing water-based inks present widespread resource and energy consumption issues, as well as environmental concerns.

[0005] Therefore, there is an urgent need to provide a new method for utilizing PET recycled materials and at the same time solve the problems faced in preparing water-based inks from fossil raw materials.

[0006] Summary of the Invention

[0007] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention proposes a method for preparing a recycled resin from PET recycled material and its application. The method of the present invention uses PET recycled material as the main material, uses specific polyols and polyacids / polyacid anhydrides as auxiliary materials, and selects a specific catalyst for use in combination to prepare the recycled resin, and the recycled resin is applied to the preparation of water-based ink. During the preparation of the water-based ink, the addition of alkaline solution can make the water-based ink achieve the same printing performance as acrylic resin ink. The method of the present invention does not generate waste during the polymerization process, achieving a 100% recycling rate of waste plastics. Not only does it save fossil raw materials, but it also makes full use of PET recycled materials, achieving the goal of turning waste into treasure.

[0008] A first aspect of the present invention provides a method for preparing recycled resin from PET recycled material.

[0009] Specifically, a method for preparing recycled resin from PET recycled material comprises the following steps:

[0010] Mixing PET recycled material, polyol and catalyst, heating to react, cooling, adding polyacid or polyacid anhydride to react, cooling after the reaction, and obtaining recycled resin by cooling.

[0011] The polyol is selected from at least one of diethylene glycol, tripropylene glycol, and polyethylene glycol;

[0012] The average functionality of the polyacid is >2;

[0013] The catalyst is selected from at least two of zinc acetate, manganese acetate, and tetrabutyl titanate.

[0014] Preferably, the polyacid is triazine polycarboxylic acid; and the polyacid anhydride is trimellitic anhydride.

[0015] Preferably, the catalyst is a combination of zinc acetate and tetrabutyl titanate, a combination of manganese acetate and tetrabutyl titanate, or a combination of zinc acetate and manganese acetate. Different catalyst combinations also affect degradation efficiency and polymerization efficiency. The combination of zinc acetate and tetrabutyl titanate has better degradation efficiency and polymerization efficiency than the combination of manganese acetate and tetrabutyl titanate, and the combination of zinc acetate and manganese acetate is more preferred.

[0016] The above-mentioned temperature-raising reaction is a degradation reaction, and the above-mentioned reaction carried out by adding the polyacid or polyacid anhydride is a polymerization reaction.

[0017] Preferably, the mass ratio of the PET recycled material, polyol, catalyst, and polyacid is 100:(160-400):(0.08-0.5):(50-100); further preferably, the mass ratio of the PET recycled material, polyol, catalyst, and polyacid is 100:(184-384):(0.1-0.5):(50-100).

[0018] Preferably, the reaction temperature of the temperature-elevated reaction is 170-260°C, preferably 180-260°C.

[0019] Preferably, the reaction time of the temperature-raising reaction is 0.8-6 hours, preferably 1-6 hours, for example, the reaction time is 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, or 6 hours.

[0020] Preferably, the temperature-elevated reaction is carried out under a protective atmosphere, such as nitrogen or a rare gas.

[0021] Preferably, the temperature-elevated reaction is carried out under stirring at a speed of 300-2000 r / min, for example, at a speed of about 300 r / min, 800 r / min, 1200 r / min, or 1800 r / min. That is, the mixture formed by mixing the PET recycled material, polyol, and catalyst is subjected to a temperature-elevated reaction at a certain speed.

[0022] Preferably, the cooling is to 100-240°C, preferably 120-240°C, for example, to about 120°C, 130°C, 140°C, 150°C, 160°C.

[0023] Preferably, the reaction time of adding the polyacid or polyacid anhydride is 1.5-6 hours, preferably 2-6 hours, for example 2 hours, 3 hours, 4 hours, 5 hours, or 6 hours.

[0024] Preferably, the reaction is carried out in a device equipped with a thermometer, a stirring device, a nitrogen bubbling device and a water separator.

[0025] The second aspect of the present invention provides an application of a method for preparing recycled resin using PET recycled material.

[0026] Specifically, the method for preparing recycled resin from PET recycled material is used in preparing water-based ink.

[0027] A water-based ink comprises recycled resin prepared by the method for preparing recycled resin from PET recycled material, alkali solution and additives.

[0028] Preferably, the alkali solution is selected from at least one of sodium hydroxide solution, potassium hydroxide solution, aqueous ammonia, and ethanolamine solution. Different types of alkali can affect the drying speed of water-based inks prepared using the recycled resin, thereby affecting printing efficiency. The present invention selects a specific alkali solution, which helps improve the drying speed of water-based inks prepared using the recycled resin.

[0029] Preferably, after adding the alkali solution, the mixture is dispersed for 10-30 minutes, preferably 15-30 minutes.

[0030] Preferably, the water-based ink further includes a color paste and / or a solvent.

[0031] Preferably, the color paste includes color pastes of various colors, such as blue color paste, red color paste, and orange color paste.

[0032] Preferably, the solvent comprises water.

[0033] Preferably, the additives include at least one of a defoamer, a leveling agent, an antifreeze agent, a preservative, a wetting agent, and a wax slurry, all of which are conventional commercial additives.

[0034] Preferably, the defoaming agent includes any one of mineral oils, alcohols, fatty acids and fatty acid esters, amides, phosphates, silicones, polyethers, and polyether-modified polysiloxane defoamers, such as BYK-012 defoamer.

[0035] Preferably, the leveling agent includes any one of polyacrylates and carboxymethyl cellulose.

[0036] Preferably, the antifreeze agent includes any one of ethanol, isopropanol, ethylene glycol, propylene glycol, diethylene glycol, ethylene glycol butyl ether, propylene glycol butyl ether, and ethylene glycol butyl ether acetate.

[0037] Preferably, the preservative includes any one of 5-chloro-2-methyl-4-isothiazolin-3-one, benzimidazole esters, Dovicil-75, and 1,2-benzisothiazolin-3-one.

[0038] Preferably, the wetting agent includes any one of a polyether wetting agent, a polyester wetting agent, and a sodium alkylbenzene sulfonate wetting agent.

[0039] According to a preferred embodiment of the present invention, the water-based ink comprises, by weight, 10-35 parts of recycled resin, 0-50 parts of color paste, 5-20 parts of alkali solution, and 0.5-5 parts of additives; further preferably, the water-based ink comprises, by weight, 10-30 parts of recycled resin, 40-50 parts of color paste, 6.3-17.2 parts of alkali solution, and 1.5-2.2 parts of additives.

[0040] Preferably, the water-based ink further comprises water, and the water content is 10-40 parts, more preferably 15.7-29.5 parts.

[0041] A method for preparing a water-based ink comprises the following steps:

[0042] The recycled resin prepared by the above method of preparing recycled resin from PET recycled material, alkali solution and additives are mixed, and the pH is adjusted to alkaline to prepare the water-based ink.

[0043] Preferably, when the recycled resin is added, color paste and / or solvent are also added.

[0044] Preferably, the pH is adjusted to 8.5±1.1, more preferably to 8.5±1.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] The method described herein utilizes recycled PET as the main material, with specific polyols and polyacids / anhydrides with an average functionality greater than 2 as auxiliary materials, and a selected catalyst for use in combination to produce a recycled resin. This recycled resin is then used in the preparation of water-based inks. Combined with alkali solution, the water-based inks achieve the same printing performance as acrylic resin inks. The polymerization process described herein produces no waste, achieving a 100% recycling rate for waste plastics. The resulting recycled resin is then directly mixed with color paste, alkali solution, and additives to produce water-based inks. This process eliminates the need for separation and impurity removal of the recycled resin, generates no pollutants, and fully utilizes the raw materials. This not only conserves fossil raw materials but also fully utilizes recycled PET, achieving the goal of turning waste into valuable resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] FIG1 is a schematic diagram of the finger touch test method for measuring the initial drying of ink;

[0048] Figure 2 shows sample images of water-based ink printed on kraft paper in Application Example 3, Standard Example 3, and Comparative Application Example 3;

[0049] Figure 3 shows sample images of water-based ink printed on white cardboard for Application Example 3, Standard Example 3, and Comparative Application Example 3. DETAILED DESCRIPTION

[0050] In order to make the technical solution of the present invention more clearly understood by those skilled in the art, the following examples are given for illustration. It should be noted that the following examples do not limit the scope of protection claimed by the present invention.

[0051] Unless otherwise specified, the raw materials, reagents, or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0052] The sources of raw materials used in the following examples and comparative examples are as follows:

[0053] The PET recycled materials come from Dongguan Xingyu New Materials Co., Ltd.

[0054] TLAY2 orange, TLAY6 blue, and TLAY4 red are sourced from Guangdong Tianlong Ink Co., Ltd.

[0055] LW-6502C comes from Nanjing Tianshi New Material Technology Co., Ltd.

[0056] BYK-012 is from BYK Chemicals.

[0057] 0663 resin is a polyacrylic resin sourced from Guangdong Tianlong Ink Co., Ltd.

[0058] Example 1

[0059] A method for preparing recycled resin from PET recycled material comprises the following steps:

[0060] PET recycled material, diethylene glycol, zinc acetate and tetrabutyl titanate are added to a four-necked flask equipped with a thermometer, a stirring device, a nitrogen bubbling device and a water separator. The temperature is raised to 230°C at a speed of 1500 r / min and a nitrogen atmosphere. The reaction (degradation reaction) is carried out for 1 hour to obtain a degradation product. The temperature is then lowered to 160°C, and meta-triazine polycarboxylic acid is added to continue the reaction (polymerization reaction) for 2 hours. When the water volume in the water separator reaches the theoretical value and the temperature drops to room temperature, the material is discharged to obtain a recycled resin.

[0061] The preparation process of the recycled resins in Examples 2-3 and Comparative Examples 1-5 is similar to that in Example 1, except that the types or amounts of polyols, polyacids / polyacid anhydrides, catalysts, reaction temperatures or times are different. Specific parameters are shown in Table 1.

[0062] Table 1: Reaction conditions

[0063] Note: “ / ” in Table 1 indicates that since no catalyst was added in Comparative Example 3, the molecular weight of the degradation product was too large and the obtained degradation product could not undergo polymerization reaction.

[0064] The degradation products and regenerated resins prepared in Examples 1-3 and Comparative Examples 1-5 were tested for their relevant properties. The test standards are as follows. The test results are shown in Tables 2 and 3.

[0065] Acid value: refer to GB / T2895-2008 "Determination of partial acid value and total acid value of plastic polyester resin";

[0066] Hydroxyl value: refer to GB / T12008.3-2009 "Plastic polyether polyols - Part 3: Determination of hydroxyl value";

[0067] Softening point: Refer to GB / T 4507-2014 "Determination of softening point of asphalt - Ring and ball method".

[0068] Table 2: Degradation product test results

[0069] Note: The “ / ” in Table 2 indicates that since no catalyst was added in Comparative Example 3, the degradation product precipitated at room temperature due to its large molecular weight and could not be dissolved, so the specific acid value and hydroxyl value could not be measured.

[0070] As can be seen from Table 2, changing the type of degradation catalyst significantly affects the degradation time. Changing the types of polyol and polyacid also affects the degradation time. In other words, the choice of polyol, polyacid, and catalyst significantly influences the degradation efficiency.

[0071] Table 3: Recycled resin test results

[0072] Note: The “ / ” in Table 3 indicates that since no catalyst was added in Comparative Example 3, the degradation product precipitated at room temperature due to its excessive molecular weight, making it difficult to proceed with the next polymerization reaction, and thus the reaction was terminated.

[0073] Table 3 shows that the choice of polyacid and polyol significantly affects the acid value, hydroxyl value, and softening point of the resulting recycled resin. The functionality of the polyacid in Comparative Example 5 is 2, resulting in a very low acid value for the recycled resin. A high acid value in the recycled resin improves the printing quality of the resulting water-based ink.

[0074] Application Examples

[0075] The preparation of water-based ink using the recycled resin prepared in Examples 1-3 and Comparative Examples 1-5 comprises the following steps:

[0076] (1) Fully mix the regenerated resin, alkali solution and water with the same mass as the alkali solution at 60°C, wait until the regenerated resin is completely dissolved, and filter through a 200-mesh filter bag to obtain the regenerated resin liquid;

[0077] (2) Then, the recycled resin liquid, color paste, solvent, defoaming agent and wax paste are mixed and the pH is adjusted to 8.5 to prepare a water-based ink.

[0078] The specific types and amounts of raw materials are shown in Table 4.

[0079] Table 4

[0080] Sample Preparation Method: The water-based inks prepared in the application examples, comparative application examples, and standard examples were printed using a standard 180-line flexographic printing tester with a capacity of 16.6 cu.cm / sq.m. Samples were printed on kraft paper and white cardboard, respectively.

[0081] Viscosity: Tested in accordance with GB / T13217.4-2008 “Test method for viscosity of liquid inks”.

[0082] pH: Use a pH meter to measure the pH of water-based ink at 30°C, and measure twice to take the average.

[0083] Resolubility: Use the observation method, with Standard Examples 1-3 as standard references, to record the ease of cleaning the flexographic printing tester after printing different groups of inks.

[0084] Initial drying: Use the finger touch test method to display the same color standard sample ink and application sample and comparison application sample ink on a standard black and white card. After printing, use a stopwatch to time the printing. Use the index and middle fingertips to touch the ink sample from bottom to top at the same frequency of 1 time / s on the black card area. After the first column is filled, touch the second column to the left and right respectively until no fingerprints are left. Stop timing at each time to judge the initial drying degree compared with the standard sample and record the initial drying time.

[0085] Abrasion resistance: Refer to GB / T 7706-2008 "Letterpress Decorative Printing" Chapter 6.8 "Ink layer abrasion resistance" related standard test.

[0086] Color rendering: CIE L*a*b* colorimetry was performed using an X-Rite Pantone eXact scanning spectrophotometer. L represents brightness, a represents red and green content and chroma, and b represents yellow and blue content and chroma.

[0087] The test results were evaluated based on the performance of comparative application examples 1-3 and three types of polyacrylic resin water-based inks (i.e., standard examples 1-3). In addition to the evaluation of specific data indicators, the comparative evaluation levels were divided into five grades: poor, slightly poor, standard, slightly better, and excellent. The results are shown in Tables 5 and 6.

[0088] Table 5

[0089] Table 6

[0090] As can be seen from Tables 5-6, the performance of the water-based ink prepared in Application Examples 1-3 is significantly better than that in the comparative application examples, and even better than that in Standard Examples 1-3.

[0091] Figure 1 is a schematic diagram of the fingertip test method for measuring the initial setting of ink. In Figure 1, a represents a standard black and white card; b represents Standard Example 2; c represents Application Example 2; d represents the point where the fingerprint disappears in the second column of Standard Example 2; and e represents the point where the fingerprint disappears in the second column of Application Example 2. As can be seen from Figure 1, Application Example 2 exhibits better initial setting than Standard Example 2.

[0092] Figure 2 shows sample images of water-based inks printed on kraft paper for Application Example 3, Standard Example 3, and Comparative Application Example 3; (a) in Figure 2 corresponds to the ink for Application Example 3, (b) corresponds to the ink for Standard Example 3, and (c) corresponds to the ink for Comparative Application Example 3.

[0093] Figure 3 shows sample pictures of water-based inks printed on white cardboard for Application Example 3, Standard Example 3, and Comparative Application Example 3; (a) in Figure 3 corresponds to the ink for Application Example 3, (b) corresponds to the ink for Standard Example 3, and (c) corresponds to the ink for Comparative Application Example 3.

[0094] As can be seen from Figures 2-3, the printing color rendering effect of the application example is better than that of the standard example and the comparative application example.

[0095] In summary, changing the type of degradation catalyst significantly impacts the degradation reaction time. Changing the types of polyols and polyacids also influences the degradation reaction time. In other words, the choice of polyol, polyacid, and catalyst significantly influences degradation efficiency. The choice of polyacid and polyol also significantly affects the acid value, hydroxyl value, and softening point of the resulting recycled resin, ultimately impacting the printing quality of water-based inks.

Claims

1. A method for preparing recycled resin from PET recycled material, characterized in that: The following steps are involved: The PET recycled material, polyol and catalyst are mixed, heated to react, cooled, and then polyacid or polyacid anhydride is added to react. After the reaction is completed, the temperature is cooled to obtain the recycled resin. The polyol is selected from at least one of diethylene glycol, tripropylene glycol and polyethylene glycol; The average functionality of the polyacid is >2; The catalyst is selected from at least two of zinc acetate, manganese acetate and tetrabutyl titanate.

2. The method according to claim 1, characterized in that The polyacid is triazine polycarboxylic acid; and the polyacid anhydride is trimellitic anhydride.

3. The method according to claim 1, characterized in that The catalyst is a combination of zinc acetate and tetrabutyl titanate, a combination of manganese acetate and tetrabutyl titanate, or a combination of zinc acetate and manganese acetate.

4. The method according to any one of claims 1 to 3, characterized in that The mass ratio of the PET recycled material, polyol, catalyst, polyacid or polyacid anhydride is 100:(160-400):(0.08-0.5):(50-100).

5. The method according to any one of claims 1 to 3, characterized in that: The reaction temperature of the temperature-raising reaction is 170-260° C.; and / or, the reaction time of the temperature-raising reaction is 0.8-6 hours; and / or, the temperature-raising reaction is carried out under a protective atmosphere; and / or, the temperature-raising reaction is carried out under stirring at a rotation speed of 300-2000 r / min.

6. The method according to any one of claims 1 to 3, characterized in that The reaction time of adding the polyacid or polyacid anhydride for reaction is 1.5-6 hours.

7. A water-based ink, characterized in that: The invention comprises a regenerated resin prepared by the method according to any one of claims 1 to 6, an alkali solution and an auxiliary agent.

8. The method for preparing the water-based ink according to claim 7, characterized in that: The following steps are involved: The regenerated resin, alkali solution and additives are mixed, and the pH is adjusted to alkaline to prepare the water-based ink.

9. The preparation method according to claim 8, characterized in that: The alkali solution is selected from at least one of sodium hydroxide solution, potassium hydroxide solution, ammonia water and ethanolamine solution.

10. The preparation method according to claim 8 or 9, characterized in that: The recycled resin is prepared by the method according to any one of claims 1 to 6.

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