A method for preparing recycled resin using PET recycled material and its application

Abstract

The present invention belongs to the technical field of plastic recycling, and discloses a method for preparing recycled resin with PET recycled material and its application. The method comprises the following steps: mixing PET recycled material, polyol and catalyst, heating for reaction, cooling, adding polyacid or polyacid anhydride for reaction, cooling after the reaction, and obtaining 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 greater than 2; the catalyst is selected from at least two of zinc acetate, manganese acetate and tetrabutyl titanate. The present invention applies recycled resin to the preparation of water-based ink, so that the water-based ink has the same printing expression as acrylic resin ink. No waste is generated during the polymerization process of the method of the present invention, and the recycling rate of waste plastics is 100%. Not only fossil raw materials are saved, but also PET recycled materials are fully utilized to achieve the purpose of turning waste into treasure.

Description

Technical Field

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

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

[0003] The production cost of PET recycled materials is relatively low, and it can also reduce the demand for new raw materials, save energy, reduce carbon emissions, and comply with environmental protection concepts. At present, relevant literature has mentioned that PET recycled materials can be degraded to prepare adhesives or inks, but there have been no reports on the direct degradation of PET recycled materials for the preparation of water-based inks.

[0004] Environmentally friendly water-based packaging printing ink binders are mainly water-based polyacrylic resins, and a small amount of high-end inks use polyurethane as a binder. Both polyacrylic resins and polyurethanes require petrochemical raw materials to be prepared through polymerization reactions. The production process consumes energy and petrochemical raw materials and produces certain polluting waste. Therefore, existing water-based inks have relatively common resource, energy consumption, and environmental protection problems.

[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. Summary of the invention

[0006] 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 materials and its application. The method of the present invention adopts PET recycled materials as the main body, uses specific polyols and polyacids / polyacid anhydrides as auxiliary materials, and selects specific catalysts for use in combination to prepare recycled resin, and the recycled resin is applied to the preparation of water-based ink. In the process of preparing water-based ink, alkali solution is used to make the water-based ink achieve the same printing expression as acrylic resin ink. No waste is generated during the polymerization process of the method of the present invention, and a 100% recycling rate of waste plastics is achieved. Not only does it save fossil raw materials, but it also makes full use of PET recycled materials to achieve the purpose of turning waste into treasure.

[0007] A first aspect of the present invention provides a method for preparing a recycled resin from PET recycled material.

[0008] Specifically, a method for preparing recycled resin from PET recycled material comprises the following steps:

[0009] 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 a recycled resin.

[0010] The polyol is selected from at least one of diethylene glycol, tripropylene glycol and polyethylene glycol;

[0011] The average functionality of the polyacid is >2;

[0012] The catalyst is selected from at least two of zinc acetate, manganese acetate and tetrabutyl titanate.

[0013] Preferably, the polyacid is triazine polycarboxylic acid; and the polyacid anhydride is trimellitic anhydride.

[0014] 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 combinations of catalysts will also affect the degradation efficiency and polymerization efficiency. The degradation efficiency and polymerization efficiency of the combination of zinc acetate and tetrabutyl titanate are better than those of manganese acetate and tetrabutyl titanate, and the combination of zinc acetate and manganese acetate is more preferred.

[0015] 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.

[0016] 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).

[0017] Preferably, the reaction temperature of the temperature-raising reaction is 170-260°C, preferably 180-260°C.

[0018] 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.

[0019] Preferably, the temperature-raising reaction is carried out under a protective atmosphere, for example, the protective atmosphere is nitrogen or a rare gas.

[0020] Preferably, the temperature-raising 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, the polyol, and the catalyst is subjected to a temperature-raising reaction at a certain speed.

[0021] 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.

[0022] Preferably, the reaction time of adding the polyacid or polyacid anhydride is 1.5-6 hours, preferably 2-6 hours, such as 2 hours, 3 hours, 4 hours, 5 hours, 6 hours.

[0023] Preferably, the reaction is carried out in a device equipped with a thermometer, a stirring device, a nitrogen bubbling device and a water separator.

[0024] The second aspect of the present invention provides an application of a method for preparing a recycled resin using PET recycled material.

[0025] Specifically, the method for preparing recycled resin using PET recycled material is used in preparing water-based ink.

[0026] A water-based ink comprises the recycled resin prepared by the method for preparing recycled resin with PET recycled material, alkali solution and additives.

[0027] Preferably, the alkali solution is selected from at least one of sodium hydroxide solution, potassium hydroxide solution, ammonia water, and ethanolamine solution. Different types of alkali will affect the printing drying speed corresponding to the water-based ink prepared using the recycled resin, thereby affecting the printing efficiency. The present invention selects a specific alkali solution, which helps to improve the printing drying speed corresponding to the water-based ink prepared using the recycled resin.

[0028] Preferably, after adding the alkali solution, the dispersion is carried out for 10-30 minutes, preferably 15-30 minutes.

[0029] Preferably, the water-based ink further includes color paste and / or solvent.

[0030] Preferably, the color paste includes color pastes of various colors, such as blue color paste, red color paste, and orange color paste.

[0031] Preferably, the solvent comprises water.

[0032] Preferably, the additives include at least one of a defoamer, a leveling agent, an antifreeze agent, a preservative, a wetting agent, and wax slurry, all of which are conventional commercial additives.

[0033] Preferably, the defoamer 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.

[0034] Preferably, the leveling agent includes any one of polyacrylates and carboxymethyl cellulose.

[0035] 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.

[0036] Preferably, the preservative includes any one of 5-chloro-2-methyl-4-isothiazoline-3-one, benzimidazole esters, Dovicil-75, and 1,2-benzisothiazolin-3-one.

[0037] Preferably, the wetting agent includes any one of a polyether wetting agent, a polyester wetting agent, and a sodium alkylbenzene sulfonate wetting agent.

[0038] According to a preferred embodiment of the present invention, the water-based ink, calculated by weight, comprises 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, calculated by weight, comprises 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.

[0039] Preferably, the water-based ink also includes water, and the water content is 10-40 parts, more preferably 15.7-29.5 parts.

[0040] A method for preparing a water-based ink comprises the following steps:

[0041] The recycled resin prepared by the method for preparing recycled resin from PET recycled materials, alkali solution and additives are mixed, and the pH is adjusted to alkaline to prepare the water-based ink.

[0042] Preferably, when the recycled resin is added, color paste and / or solvent are also added.

[0043] Preferably, the pH is adjusted to 8.5±1.1, more preferably the pH is adjusted to 8.5±1.1.

[0044] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0045] The method of the present invention uses PET recycled material as the main body, uses specific polyols and polyacids / polyacid anhydrides with an average functionality of >2 as auxiliary materials, and selects specific catalysts for use in combination to prepare recycled resin, and the recycled resin is applied to the preparation of water-based ink, and is combined with alkali solution so that the water-based ink can achieve the same printing performance as acrylic resin ink. No waste is generated during the polymerization process of the method of the present invention, and the recycling rate of waste plastics is 100%. The prepared recycled resin is directly mixed with color paste, alkali solution, and additives to prepare water-based ink. The process does not require separation and impurity removal of the recycled resin, and no pollutants are generated, and the raw materials are fully utilized. Not only does it save fossil raw materials, but it also makes full use of PET recycled materials to achieve the purpose of turning waste into treasure. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a schematic diagram of determining the initial drying property of ink by finger touch test method;

[0047] Figure 2 Sample pictures of water-based ink printed on kraft paper for Application Example 3, Standard Example 3 and Comparative Application Example 3;

[0048] Figure 3 The sample pictures are printed on white cardboard using water-based ink for Application Example 3, Standard Example 3 and Comparative Application Example 3. DETAILED DESCRIPTION

[0049] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

[0050] 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.

[0051] The sources of raw materials used in the following examples and comparative examples are as follows:

[0052] The PET recycled materials come from Dongguan Xingyu New Materials Co., Ltd.

[0053] TLAY2 orange, TLAY6 blue and TLAY4 red are from Guangdong Tianlong Ink Co., Ltd.

[0054] LW-6502C comes from Nanjing Tianshi New Material Technology Co., Ltd.

[0055] BYK-012 is from BYK Chemicals.

[0056] 0663 resin is a polyacrylic resin, which comes from Guangdong Tianlong Ink Co., Ltd.

[0057] Example 1

[0058] A method for preparing recycled resin from PET recycled material comprises the following steps:

[0059] Add PET recycled material, diethylene glycol, zinc acetate and tetrabutyl titanate into a four-necked bottle equipped with a thermometer, a stirring device, a nitrogen bubbling device and a water separator, heat to 230°C at a speed of 1500r / min and a nitrogen atmosphere, react (degradation reaction) for 1 hour to obtain a degradation product, then cool to 160°C, add meta-triazine polycarboxylic acid and continue to react (polymerization reaction) for 2 hours, wait until the water volume in the water separator reaches the theoretical value, and wait until the temperature drops to room temperature to discharge the material to obtain a recycled resin.

[0060] The preparation process of the recycled resin 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. The specific parameters are shown in Table 1.

[0061] Table 1: Reaction conditions

[0062]

[0063]

[0064] Note: “ / ” in Table 1 means 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.

[0065] 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 were as follows. The test results are shown in Tables 2 and 3.

[0066] Acid value: refer to GB / T2895-2008 "Determination of partial acid value and total acid value of plastic polyester resin";

[0067] Hydroxyl value: refer to GB / T12008.3-2009 "Plastic polyether polyols Part 3: Determination of hydroxyl value";

[0068] Softening point: refer to GB / T 4507-2014 "Bitumen softening point determination method - ring and ball method";

[0069] Table 2: Degradation product test results

[0070]

[0071]

[0072] 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.

[0073] As can be seen from Table 2, when the type of catalyst for the degradation reaction is changed, the time required for the degradation reaction is greatly affected. When the types of polyols and polyacids are changed, the time required for the degradation reaction is also affected. That is, the selection of polyols, polyacids and catalysts will significantly affect the degradation efficiency.

[0074] Table 3: Regenerated resin test results

[0075] Acid value (mgKOH / g) Hydroxyl value (mgKOH / g) Softening point(℃) Example 1 95 273 119 Example 2 101 271 121 Example 3 109 255 133 Comparative Example 1 87 214 97 Comparative Example 2 92 202 103 Comparative Example 3 / / / Comparative Example 4 62 282 105 Comparative Example 5 16 244 113

[0076] 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 carry out the next polymerization reaction, and thus the reaction was terminated.

[0077] As can be seen from Table 3, the selection of polyacid and polyol has a significant effect on the acid value, hydroxyl value and softening point of the prepared recycled resin. The functionality of the polyacid in Comparative Example 5 is equal to 2, so the acid value of the recycled resin prepared in Comparative Example 5 is very low. The high acid value of the recycled resin is conducive to improving the printing effect of the finally prepared water-based ink.

[0078] Application Examples

[0079] The preparation of water-based ink using the recycled resin prepared in Examples 1-3 and Comparative Examples 1-5 comprises the following steps:

[0080] (1) Fully mix the regenerated resin, alkali solution and water with the same mass as the alkali solution at 60°C, wait for the regenerated resin to be completely dissolved, and filter through a 200-mesh filter bag to obtain the regenerated resin liquid;

[0081] (2) Then, the regenerated resin liquid, color paste, solvent, defoamer and wax paste are mixed and the pH is adjusted to 8.5 to prepare a water-based ink.

[0082] The specific types and amounts of raw materials are shown in Table 4.

[0083] Table 4

[0084]

[0085]

[0086] Sample preparation method: The water-based ink prepared in the application example, comparative application example, and standard example was printed using a standard 180-line flexographic printing tester with a capacity of 16.6 cu.cm / sq.m. The samples were printed on kraft paper and white card paper respectively.

[0087] Viscosity: Tested in accordance with GB / T13217.4-2008 “Test Method for Liquid Ink Viscosity”.

[0088] pH: Use a pH meter to measure the pH of the water-based ink at 30°C and measure twice to take the average.

[0089] 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.

[0090] Initial drying: Use the finger touch test method to display the same color of standard example ink and application example and comparison application example ink on the standard black and white card. After printing, use a stopwatch to time. Use the index finger and middle finger to touch the ink sample from bottom to top at the same frequency at a frequency of 1 time / s in 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 respectively to judge the initial drying degree compared with the standard sample, and record the initial drying time.

[0091] Abrasion resistance: Refer to GB / T 7706-2008 "Letterpress Decorative Printing" Chapter 6.8 "Ink layer abrasion resistance" related standard test.

[0092] Color rendering: X-Rite Pantone eXact scanning spectrophotometer was used to measure CIE L*a*b* color. The L value represents brightness, the a value represents the red and green content and chroma, and the b value represents the yellow and blue content and chroma.

[0093] 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.

[0094] Table 5

[0095]

[0096]

[0097] Table 6

[0098]

[0099] It can be seen from Tables 5-6 that 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.

[0100] Figure 1 This is a schematic diagram of determining the initial drying property of ink by finger touch test method; Figure 1 In the figure, a represents the standard black and white card; b represents standard example 2; c represents application example 2; d represents the point where the second column of fingerprints in standard example 2 disappears; and e represents the point where the second column of fingerprints in application example 2 disappears. Figure 1It can be seen that the initial drying property of application example 2 is better than that of standard example 2.

[0101] Figure 2 Sample pictures of water-based ink printed on kraft paper for Application Example 3, Standard Example 3 and Comparative Application Example 3; Figure 2 (a) corresponds to the ink of Application Example 3, (b) corresponds to the ink of Standard Example 3, and (c) corresponds to the ink of Comparative Application Example 3.

[0102] Figure 3 Sample pictures of water-based ink printed on white cardboard for Application Example 3, Standard Example 3 and Comparative Application Example 3; Figure 3 (a) corresponds to the ink of Application Example 3, (b) corresponds to the ink of Standard Example 3, and (c) corresponds to the ink of Comparative Application Example 3.

[0103] from Figure 2-3 It can be seen that the printing color rendering effect of the application example is better than that of the standard example and the comparative application example.

[0104] In summary, when the type of catalyst for the degradation reaction is changed, the time required for the degradation reaction is greatly affected. When the types of polyols and polyacids are changed, the time required for the degradation reaction is also affected. That is, the selection of polyols, polyacids and catalysts will significantly affect the degradation efficiency. The selection of polyacids and polyols also has a significant impact on the acid value, hydroxyl value and softening point of the prepared recycled resin. Ultimately, it also affects the printing effect 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 a recycled resin. When the polyol is diethylene glycol, the catalyst is a combination of zinc acetate and tetrabutyl titanate, and the polyacid is triazine polycarboxylic acid; Or, when the polyol is tripropylene glycol, the catalyst is a combination of manganese acetate and tetrabutyl titanate, the polyacid is triazine polycarboxylic acid, and the polyacid anhydride is trimellitic anhydride; Alternatively, when the polyol is polyethylene glycol, the catalyst is a combination of zinc acetate and manganese acetate, and the polyacid anhydride is trimellitic anhydride.

2. The method according to claim 1, 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).

3. The method according to any one of claims 1 to 2, 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.

4. The method according to any one of claims 1 to 2, characterized in that: The reaction time of adding the polyacid or polyacid anhydride is 1.5-6 hours.

5. A water-based ink, characterized in that: The invention comprises a regenerated resin, an alkali solution and an auxiliary agent prepared by the method according to any one of claims 1 to 4; the alkali solution comprises any one of ammonia water, diethylamine or triethylamine.

6. The method for preparing the water-based ink according to claim 5, 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; The recycled resin is prepared by the method according to any one of claims 1 to 4.

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