Method for separating resin from coatings

Abstract

The present invention relates to the field of coating technology, and in particular to a method for separating resins from coatings. The present invention selects an organic solvent with a solubility parameter greater than 9.0 as the first solvent, which can fully dissolve resins with a molecular weight of 2000Da to 200,000Da and reactive diluents with a molecular weight of less than 1000Da; and uses triethylamine, diethylamine, tributylamine, ethylenediamine, diisopropylamine, and triethanolamine as the second solvent, which can fully dissolve the reactive diluent. However, the solubility of the resin in the second solvent is less than 0.1g, which can form a sufficient solubility difference so that the resin and the reactive diluent can be completely separated. The separation method is simple and efficient, has no special requirements for the viscosity of the coating, and can cover resins and reactive diluents with a large molecular weight range. It has a wide range of applications, good separation effect, can assist in obtaining more accurate results in resin analysis, and has good application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, in particular to a method for separating resin in coatings. Background Art

[0002] When analyzing resins in coatings, they are often interfered with by reactive diluents, making it difficult to accurately analyze the resin structure. Therefore, the two need to be separated to improve the accuracy of the analysis. Traditional separation methods are mainly divided into two categories: (1) filtration using permeable membranes; (2) washing and separation using organic solvents. However, since the resin information in the sample is mostly unknown, it is difficult to accurately select the permeable membrane pore size, and the material is often viscous, so the use of permeable membrane filtration has low efficiency and poor separation effect. Separation using organic solvent washing exploits the solubility difference between the resin and the reactive diluent. The former is insoluble in non-polar petroleum ether, while the latter can be dissolved in petroleum ether when its functional group content is low. Therefore, this method is only suitable for reactive diluents with low functionality (1-2 functional groups), such as 2-phenoxyethyl acrylate (PHEA), isobornyl acrylate (IBOA), 1,6-ethylene glycol diacrylate (HDDA), and tripropylene glycol diacrylate (TPGDA). Common reactive diluents with high functionality (3-6 functional groups), such as trimethylolpropane triacrylate (TMPTA), pentaerythritol triacrylate (PET4A), and polydipentaerythritol hexaacrylate (DPHA), are not well soluble in petroleum ether due to their large molecular weight and strong polarity, making this method unsuitable for separation. Furthermore, for samples with high viscosity, even those containing low-functionality reactive diluents can be difficult to disperse in petroleum ether, resulting in incomplete separation. Summary of the Invention

[0003] Based on this, it is necessary to provide a separation method with high efficiency, good separation effect and suitable for resin in coatings.

[0004] The present invention provides a method for separating resin in coatings, which comprises the following steps:

[0005] dissolving the coating in a first solvent to prepare a first solution;

[0006] adding the first solution to a second solvent under stirring to precipitate the resin and perform phase separation;

[0007] The coating comprises the resin and the reactive diluent, the molecular weight of the resin is 2000Da to 200000Da, and the molecular weight of the reactive diluent is less than or equal to 1000Da; the first solvent is an organic solvent with a solubility parameter greater than 9.0, and the second solvent is one or more of triethylamine, diethylamine, tributylamine, ethylenediamine, diisopropylamine and triethanolamine.

[0008] In some embodiments, the volume of the coating is 3% to 80% of the volume of the first solvent.

[0009] In some embodiments, the first solvent is one or more of tetrahydrofuran, chloroform, and acetone.

[0010] In some embodiments, the volume of the second solvent is at least 50 times the volume of the first solvent.

[0011] In some embodiments, the stirring speed is 200 rpm to 600 rpm, and the adding speed is 1 to 5 drops / second.

[0012] In some embodiments, the phase separation method is centrifugation, the centrifugal speed is 3000 rpm to 7000 rpm, and the centrifugal time is 5 min to 15 min.

[0013] In some embodiments, the resin obtained by phase separation is treated 1-2 times according to the following steps and then dried:

[0014] The resin is dissolved in another portion of the first solvent to prepare a second solution, and the second solution is added to another portion of the second solvent under stirring to precipitate the resin and perform phase separation.

[0015] In some embodiments, the resin structure includes at least one of the following groups: -OH, -COOH, and -COONH-.

[0016] In some embodiments, the resin is one or more of polyurethane acrylate resin, polyester acrylate, polyether acrylate, epoxy acrylate, and pure acrylic resin.

[0017] In some embodiments, the molecular weight of the reactive diluent is 250 Da to 1000 Da.

[0018] In some embodiments, the reactive diluent has a functionality of 3 to 6.

[0019] In some embodiments, the reactive diluent is at least one of pentaerythritol triacrylate, pentaerythritol tetraacrylate, trimethylolpropane triacrylate, polydipentaerythritol hexaacrylate, and ditrimethylolpropane tetraacrylate.

[0020] By selecting an organic solvent with a solubility parameter greater than 9.0 as the first solvent, resins with a molecular weight of 2000Da to 200,000Da and reactive diluents with a molecular weight of less than 1000Da can be fully dissolved, thereby avoiding the problem of difficulty in dispersion in petroleum ether due to excessive viscosity in traditional methods. By using triethylamine, diethylamine, tributylamine, ethylenediamine, diisopropylamine, and triethanolamine as the second solvent, reactive diluents with a molecular weight of less than 1000Da can also be fully dissolved. However, the solubility of resins with a molecular weight of 2000Da to 200,000Da in the second solvent is less than 0.1g, thereby forming a sufficient solubility difference to completely separate the resin and reactive diluent. This separation method is simple and efficient, and does not require pre-analysis of sample information such as particle size; it has no special requirements for the viscosity of the coating, and even samples with higher viscosity can be well separated; it can cover resins and reactive diluents with a large molecular weight range, and has a wide range of applications, solving the problem that traditional organic solvent separation methods can only separate reactive diluents with low functionality; it has good separation effect, can assist in obtaining more accurate results in resin analysis, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The retention time of pentaerythritol tri / tetraacrylate (PET3 / 4A), polydipentaerythritol penta / hexaacrylate (DPH5 / 6A) and trimethylolpropane triacrylate (TMPTA) standards;

[0022] Figure 2 It is the HPLC chromatogram of Comparative Example 1;

[0023] Figure 3 The HPLC chromatogram of Example 1 is shown. DETAILED DESCRIPTION

[0024] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the accompanying drawings. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present disclosure.

[0025] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the invention, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In the description of the present invention, the meaning of "several" is at least one, such as one, two, etc., unless otherwise clearly and specifically defined.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0027] In the present invention, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0028] In the present invention, when referring to numerical ranges, unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values of the range, as well as every value between such minimum and maximum values. Furthermore, when a range refers to an integer, every integer between the minimum and maximum values of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges subsumed therein.

[0029] Unless otherwise specified, the percentage contents involved in the present invention refer to mass percentage for phase mixing and solid-solid mixing, and refer to volume percentage for liquid-liquid mixing.

[0030] The percentage concentrations mentioned in the present invention, unless otherwise specified, refer to the final concentration, which refers to the percentage of the added component in the system after the addition of the component.

[0031] The temperature parameters in the present invention, unless otherwise specified, allow for either constant temperature treatment or treatment within a certain temperature range. The constant temperature treatment allows for temperature fluctuations within the precision range controlled by the instrument.

[0032] In the present invention, unless otherwise specified, molecular weight refers to weight average molecular weight.

[0033] In the present invention, "precipitation" can refer to the separation of a solid from a liquid system to form a solid-liquid phase, or it can refer to the separation of a liquid from a liquid system to form an incompatible liquid-liquid phase; "phase separation" can refer to the separation of a solid-liquid phase, or it can refer to the separation of an incompatible liquid-liquid phase; "sedimentation" can refer to the precipitation of a solid from a liquid system, or it can refer to the accumulation of a denser liquid phase at the bottom of a container after phase separation of the liquid-liquid phase.

[0034] The present invention provides a method for separating resin in coatings, which comprises the following steps:

[0035] dissolving the coating in a first solvent to prepare a first solution;

[0036] The first solution is added dropwise to the second solvent under stirring to precipitate the resin and perform phase separation;

[0037] The coating includes a resin and a reactive diluent, the molecular weight of the resin is 2000Da to 200000Da, and the molecular weight of the reactive diluent is less than or equal to 1000Da; the first solvent is an organic solvent with a solubility parameter greater than 9.0, and the second solvent is one or more of triethylamine, diethylamine, tributylamine, ethylenediamine, diisopropylamine and triethanolamine.

[0038] It is understood that the coating of the present invention may be, for example, a light-curing coating, or other coating containing a reactive diluent, which is not particularly limited herein.

[0039] Alternatively, the molecular weight of the resin may be, for example, 4000 Da, 6000 Da, 8000 Da, 10000 Da, 15000 Da, 20000 Da, 25000 Da, 30000 Da, 35000 Da, 40000 Da, 45000 Da, 50000 Da, 55000 Da, 60000 Da, 65000 Da, 70000 Da, 75000 Da, 80000 Da, 85000 Da, 90000 Da, 95000 Da, 100,000 Da, 105,000 Da, 110,000 Da, 115,000 Da, 120,000 Da, 125,000 Da, 130,000 Da, 135,000 Da, 140,000 Da, 145,000 Da, 150,000 Da, 155,000 Da, 160,000 Da, 165,000 Da, 170,000 Da, 175,000 Da, 180,000 Da, 185,000 Da, 190,000 Da or 195,000 Da.

[0040] Alternatively, the molecular weight of the reactive diluent may be, for example, 100 Da, 150 Da, 200 Da, 250 Da, 300 Da, 350 Da, 400 Da, 450 Da, 500 Da, 550 Da, 600 Da, 650 Da, 700 Da, 750 Da, 800 Da, 850 Da, 900 Da or 950 Da.

[0041] Preferably, the second solvent is triethylamine, which has a high structural similarity to commonly used 3-6-functional active diluents, has a similar polarity, and has suitable acidity and alkalinity, resulting in a better separation effect.

[0042] The solubility of a resin is usually proportional to its molecular weight. Therefore, by selecting an organic solvent with a solubility parameter greater than 9.0 as the first solvent, resins with a molecular weight of less than 200,000 Da can be well dissolved, allowing the coating sample to be fully dispersed, avoiding the problem of difficulty in dispersion in petroleum ether due to excessive viscosity in traditional organic solvent separation methods; using triethylamine, diethylamine, tributylamine, ethylenediamine, diisopropylamine and triethanolamine as the second solvent can fully dissolve active diluents with a molecular weight of less than 1,000 Da, but the solubility of resins with a molecular weight of 2,000 Da to 200,000 Da in the second solvent is less than 0.1 g, so a sufficient solubility difference can be formed to completely separate the resin and the active diluent. This separation method is simple and efficient, and does not require pre-analysis of sample information such as particle size; it has no special requirements for the viscosity of the coating, and even samples with higher viscosity can be well separated; it can cover resins and reactive diluents with a large molecular weight range, and has a wide range of applications, solving the problem that traditional organic solvent separation methods can only separate reactive diluents with low functionality; it has good separation effect, can assist in obtaining more accurate results in resin analysis, and has good application prospects.

[0043] In some embodiments, the volume of the coating is 3% to 80% of the volume of the first solvent. Alternatively, the volume of the coating may be 45% to 55% of the volume of the first solvent, or may be 5%, 10%, 20%, 30%, 40%, 50%, 60%, or 70%. Controlling the volume percentage of the coating in the first solvent within an appropriate range can further improve the separation effect. If the volume percentage is too high, it will affect the dispersion of the first solution in the second solvent, causing the active diluent to be wrapped by the resin and unable to completely separate the two. If the volume percentage is too low, it will affect the precipitation of the resin, resulting in resin loss, reduced separation efficiency, and difficult to operate the experiment.

[0044] In some embodiments, the first solvent is one or more of tetrahydrofuran, chloroform, and acetone.

[0045] In some embodiments, the volume of the second solvent is at least 50 times the volume of the first solvent. If the amount of the second solvent is too small, the polarity of the mixed solution obtained by mixing the first solution and the second solvent will be too high, which will affect the precipitation of the resin and reduce the separation efficiency.

[0046] In some embodiments, the stirring speed is 200 rpm to 600 rpm, and the addition rate is 1 to 5 drops per second. Preferably, the stirring speed is 300 rpm to 500 rpm, and the addition rate is 1 to 2 drops per second. A slower addition rate and a suitable stirring speed facilitate the precipitation of the resin.

[0047] In some embodiments, the phase separation method is centrifugation at a speed of 3000 rpm to 7000 rpm for a time of 5 to 15 minutes. Preferably, the centrifugation speed is 5000 rpm to 6000 rpm for a time of 8 to 10 minutes. Appropriate centrifugation speed and time can better separate the precipitated resin from the system.

[0048] In some embodiments, if it is necessary to collect the active diluent and the sample contains only the resin and the active diluent, the liquid after phase separation can be dried to obtain the active diluent.

[0049] Optionally, the drying temperature can be, for example, 70° C. to 120° C., or 80° C., 90° C., 100° C. or 110° C. Preferably, the drying temperature is 105° C. A suitable drying temperature can completely volatilize the solvent without damaging the reactive diluent.

[0050] Optionally, the drying time may be, for example, 1 hour to 3 hours, preferably 2 hours.

[0051] In some embodiments, the resin obtained by phase separation is treated 1 to 5 times according to the following steps and then dried:

[0052] The resin is dissolved in another portion of the first solvent to prepare a second solution, and the second solution is added to another portion of the second solvent under stirring to precipitate the resin and perform phase separation.

[0053] In some embodiments, the stirring speed is 200 rpm to 600 rpm, and the addition rate is 1 to 5 drops per second. Preferably, the stirring speed is 300 rpm to 500 rpm, and the addition rate is 1 to 2 drops per second. A slower addition rate and a suitable stirring speed facilitate the precipitation of the resin.

[0054] Treating the resin multiple times according to the above steps can reduce the amount of residual reactive diluent in the resin and minimize interference with the analysis of the resin structure. Optionally, the number of treatments can be, for example, 2, 3, or 4 times.

[0055] In some embodiments, the drying temperature may be, for example, 70° C. to 120° C., or 80° C., 90° C., 100° C., or 110° C. Preferably, the drying temperature is 105° C. A suitable drying temperature can completely volatilize the solvent without damaging the resin.

[0056] In some embodiments, the resin structure includes at least one of the following groups: -OH, -COOH, and -COONH-. Groups such as hydroxyl and carboxyl groups have strong polarity, which can make the resin's solubility parameter closer to that of the first solvent, making it less soluble in the second solvent and resulting in a more pronounced solubility difference between the resin and the reactive diluent.

[0057] In some embodiments, the resin is one or more of polyurethane acrylate, polyester acrylate, polyether acrylate, epoxy acrylate, and pure acrylic resin.

[0058] In some embodiments, the molecular weight of the reactive diluent is 250 Da to 1000 Da.

[0059] In some embodiments, the functionality of the reactive diluent is 3 to 6. Commonly used reactive diluents with 3 to 6 functional groups have a similar structure to the second solvent and are miscible in any proportion, thereby effectively achieving separation from the resin.

[0060] In some embodiments, the reactive diluent is at least one of pentaerythritol triacrylate, pentaerythritol tetraacrylate, trimethylolpropane triacrylate, polydipentaerythritol hexaacrylate, and ditrimethylolpropane tetraacrylate.

[0061] The present invention is further described in detail below with reference to specific examples and comparative examples. For experimental parameters not specified in the following specific examples, reference should be made to the instructions provided in this application document. Reference may also be made to experimental manuals in the art or other experimental methods known in the art, or to the experimental conditions recommended by the manufacturer. It will be understood that the instruments and raw materials used in the following examples are relatively specific and may not be limited to these in other specific examples. For example, drying in an oven may not be limited thereto.

[0062] Example 1

[0063] Coating sample: Contains 60% polyether polyurethane acrylic resin (molecular weight 20,000), 14% pentaerythritol tri / tetraacrylate (molecular weight 298 / 352) and 20% polydipentaerythritol penta / hexaacrylate (molecular weight 578 / 632);

[0064] (1) 2 mL of the coating sample was dissolved in 4 mL of tetrahydrofuran to obtain a tetrahydrofuran-coating solution; the tetrahydrofuran-coating solution was added dropwise at a rate of 1 drop / second to 200 mL of triethylamine stirred at 500 rpm to precipitate the resin;

[0065] (2) The system with the precipitated resin was centrifuged at 6000 rpm for 10 min to allow the resin to settle to the lower layer; the supernatant after the centrifugation was separated and placed in an oven at 105°C for 2 h to evaporate the solvent, thereby obtaining a dry active diluent;

[0066] (3) Take another 4 mL of tetrahydrofuran and dissolve the resin in the lower layer to obtain a tetrahydrofuran-resin solution; add the tetrahydrofuran-resin solution dropwise at a rate of 1 drop / second to 200 mL of triethylamine stirred at 500 rpm to precipitate the resin; centrifuge the system with the precipitated resin at 6000 rpm for 10 minutes to allow the resin to settle to the lower layer; repeat this step once;

[0067] (4) The resin finally obtained in step (3) was placed in an oven at 105° C. for 2 hours to dry the residual solvent to obtain a separated resin, and the yield was calculated.

[0068] Example 2

[0069] Paint sample: contains 24% epoxy acrylate resin (molecular weight 3000) and 17% trimethylolpropane triacrylate (molecular weight 296.4);

[0070] (1) Take 2 mL of the coating sample and dissolve it in 4 mL of chloroform to obtain a chloroform-coating solution; add the chloroform-coating solution dropwise at a rate of 2 drops / second to 200 mL of diethylamine stirred at 400 rpm to precipitate the resin;

[0071] (2) Centrifuging the system with the precipitated resin at 5000 rpm for 8 minutes to allow the resin to settle to the lower layer; separating the supernatant after the centrifugation, and placing it in an oven at 105°C for 2 hours to evaporate the solvent to obtain a dry active diluent;

[0072] (3) Take another 4 mL of chloroform and dissolve the resin in the lower layer to obtain a chloroform-resin solution; add the chloroform-resin solution to 200 mL of diethylamine stirred at 400 rpm at a rate of 2 drops / second to precipitate the resin; centrifuge the system with the precipitated resin at 5000 rpm for 8 minutes to allow the resin to settle to the lower layer; repeat this step once;

[0073] (4) The resin finally obtained in step (3) was placed in an oven at 105° C. for 2 hours to dry the residual solvent to obtain a separated resin, and the yield was calculated.

[0074] Example 3

[0075] Paint sample: contains 12% polyester acrylic resin (molecular weight 18200), 26% pure acrylic resin (molecular weight 26000), and 16% pentaerythritol tri / tetraacrylate (molecular weight 298 / 352);

[0076] (1) 2 mL of the coating sample was dissolved in 4 mL of tetrahydrofuran to obtain a tetrahydrofuran-coating solution; the tetrahydrofuran-coating solution was added dropwise at a rate of 2 drops / second to 200 mL of triethylamine stirred at 400 rpm to precipitate the resin;

[0077] (2) Centrifuging the resin-precipitated system at 7000 rpm for 10 min to allow the resin to settle to the lower layer; separating the supernatant after the centrifugation, and placing it in an oven at 105°C for 2 h to evaporate the solvent, thereby obtaining a dry active diluent;

[0078] (3) Take another 4 mL of tetrahydrofuran and dissolve the resin in the lower layer to obtain a tetrahydrofuran-resin solution; add the tetrahydrofuran-resin solution dropwise at a rate of 2 drops / second to 200 mL of triethylamine stirred at 400 rpm to precipitate the resin; centrifuge the system with the precipitated resin at 7000 rpm for 10 minutes to allow the resin to settle to the lower layer; repeat this step once;

[0079] (4) The resin finally obtained in step (3) was placed in an oven at 105° C. for 2 hours to dry the residual solvent to obtain a separated resin, and the yield was calculated.

[0080] Example 4

[0081] The results are basically the same as those in Example 1, except that the amount of tetrahydrofuran used in steps (1) and (3) is 40 mL, and the amount of triethylamine used in steps (1) and (3) is 500 mL.

[0082] Example 5

[0083] The results are basically the same as those in Example 1, except that the amount of tetrahydrofuran used in steps (1) and (3) is 2.5 mL, and the amount of triethylamine used in steps (1) and (3) is 125 mL.

[0084] Example 6

[0085] The process is basically the same as that of Example 1, except that the triethylamine in steps (1) and (3) is replaced by diisopropylamine.

[0086] Comparative Example 1

[0087] The process is basically the same as that of Example 1, except that the triethylamine in steps (1) and (3) is replaced by petroleum ether.

[0088] Comparative Example 2

[0089] The results are basically the same as those in Example 1, except that the amount of triethylamine used in steps (1) and (3) is 160 mL.

[0090] Comparative Example 3

[0091] The method is basically the same as that of Example 1, except that the molecular weight of the polyether polyurethane acrylic resin is 1500 Da.

[0092] Comparative Example 4

[0093] The method is basically the same as Example 1, except that the active diluent is changed to ethoxylated trimethylolpropane triacrylate (TMP20EOTA) with a molecular weight of 1120 Da and the content remains unchanged at 34%.

[0094] Comparative Example 5

[0095] The method is basically the same as Example 1, except that the dripping rate in steps (1) and (3) is 8 drops / second.

[0096] Comparative Example 6

[0097] The process is basically the same as that of Example 1, except that the rotation speed in steps (1) and (3) is 100 rpm.

[0098] Comparative Example 7

[0099] The results are basically the same as those in Example 1, except that the amount of tetrahydrofuran used in steps (1) and (3) is 200 mL, and the amount of triethylamine used in steps (1) and (3) is 10 L.

[0100] Comparative Example 8

[0101] The results are basically the same as those in Example 1, except that the amount of tetrahydrofuran used in steps (1) and (3) is 2.3 mL, and the amount of triethylamine used in steps (1) and (3) is 115 mL.

[0102] Characterization Tests:

[0103] Take 0.06 g of the resin separated in each example and comparative example, dilute it to 30 g with acetonitrile, fully dissolve it, filter it through a 0.45 μm organic filter membrane, and test it using the following instruments and parameters:

[0104] High-performance liquid chromatography (Agilent 1260)

[0105] Column: Eclipse Plus C18, 5 μm, 4.6 × 25 cm

[0106] Diode array detector (DAD): 210 nm

[0107] Column oven temperature: 30°C

[0108] Flow rate: 1 mL / min

[0109] Injection volume: 5 μL

[0110] Mobile phase: gradient elution

[0111]

[0112] The reactive diluents involved in the examples and comparative examples, namely pentaerythritol tri / tetraacrylate (PET3 / 4A), polydipentaerythritol penta / hexaacrylate (DPH5 / 6A) and trimethylolpropane triacrylate (TMPTA), were prepared as standard samples, and HPLC tests were performed using the above instrument and according to the above parameters to obtain the retention time of each sample (see Figure 1 ), and then integrate the corresponding positions in the graphs of each embodiment and comparative example to determine the residual amount of the active diluent. The results are listed in Table 1; the instrumental method detection limit is 0.5%. If the active diluent content is less than 0.5%, it is confirmed that the separation degree between the resin and the active diluent in the sample has exceeded 99%.

[0113] Table 1

[0114] Group Resin yield Total residual active diluent Example 1 ＞95％ ＜0.5％ Example 2 ＞90％ ＜0.5％ Example 3 ＞93％ ＜0.5％ Example 4 ＞90％ ＜0.5％ Example 5 ＞92％ ＜0.5％ Example 6 ＞90％ ＜0.5％ Comparative Example 1 Cannot be separated 12.0％ Comparative Example 2 ＜85％ Cannot be completely separated Comparative Example 3 Cannot be completely separated and cannot be calculated Cannot be completely separated Comparative Example 4 Cannot be completely separated and cannot be calculated 20.0％ Comparative Example 5 Cannot be completely separated and cannot be calculated 2.8％ Comparative Example 6 Cannot be completely separated and cannot be calculated 1.7％ Comparative Example 7 ＜80％ ＜0.5％ Comparative Example 8 Cannot be completely separated and cannot be calculated 5.5％

[0115] from Figure 3 It can be seen that in Example 1, no active diluent remains after separation, and no peak appears at the corresponding position. As can be seen from Table 1, the active diluent content in Examples 1 to 6 is less than 0.5%, and the separation degree between the resin and the active diluent in the samples exceeds 99%. The recovery rate is maintained at more than 90%. Compared with the preferred Example 1, the resin recovery rate of Examples 4 to 6 is reduced.

[0116] from Figure 2 As shown in Table 1, in Comparative Example 1, due to the insufficient solubility of petroleum ether for the active diluent, although it can form a solubility difference with tetrahydrofuran, it still leads to the residue of active diluent, and the total residue is as high as 12%; in Comparative Example 2, the amount of triethylamine used is too small, resulting in the resin wrapping the active diluent during precipitation, causing residue; in Comparative Example 3, the molecular weight of the resin is too small, and it cannot form a good solubility difference with the active diluent, and cannot be well precipitated and completely separated; in Comparative Example 4, the molecular weight of the active diluent is too large, and the solubility in triethylamine is too low. The solubility is poor, resulting in residue; in Comparative Example 5, the dripping speed is too fast, and the resin easily wraps the active diluent when precipitating, resulting in residue; in Comparative Example 6, the rotation speed is too slow, which also affects the precipitation of the resin, resulting in a low recovery rate and active diluent residue; in Comparative Example 7, the volume proportion of the coating in tetrahydrofuran is too low. Although there is almost no active diluent residue, it leads to a large loss of resin during separation, high cost, and difficult experiment operation; in Comparative Example 8, the volume proportion of the coating in tetrahydrofuran is too high, and the resin wraps the active diluent when precipitating, resulting in residue.

[0117] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0118] The above-described embodiments merely represent several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art may make several modifications and improvements without departing from the concept of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be based on the appended claims, and the description and drawings may be used to interpret the content of the claims.

Claims

1. A method for separating resin from coatings, characterized in that: The following steps are involved: dissolving the coating in a first solvent to prepare a first solution; adding the first solution to a second solvent under stirring to precipitate the resin and perform phase separation; The coating comprises the resin and the reactive diluent, the molecular weight of the resin is 2000Da to 200000Da, and the molecular weight of the reactive diluent is less than or equal to 1000Da; the first solvent is an organic solvent with a solubility parameter greater than 9.0, and the second solvent is one or more of triethylamine, diethylamine, tributylamine, ethylenediamine, diisopropylamine and triethanolamine.

2. The separation method according to claim 1, wherein The volume of the coating is 3% to 80% of the volume of the first solvent.

3. The separation method according to claim 1, characterized in that The first solvent is one or more of tetrahydrofuran, chloroform and acetone.

4. The separation method according to claim 1, wherein The volume of the second solvent is at least 50 times the volume of the first solvent.

5. The separation method according to claim 1, characterized in that The stirring speed is 200 rpm to 600 rpm, and the adding speed is 1 to 5 drops / second; and / or The phase separation method is centrifugation, the centrifugal speed is 3000 rpm to 7000 rpm, and the centrifugal time is 5 min to 15 min.

6. The separation method according to claim 1, characterized in that The resin obtained by phase separation is treated 1 to 5 times according to the following steps and then dried: The resin is dissolved in another portion of the first solvent to prepare a second solution, and the second solution is added to another portion of the second solvent under stirring to precipitate the resin and perform phase separation.

7. The separation method according to any one of claims 1 to 6, characterized in that The resin structure includes at least one of the following groups: -OH, -COOH, and -COONH-.

8. The separation method according to any one of claims 1 to 6, characterized in that The resin is one or more of polyurethane acrylic resin, polyester acrylate, polyether acrylate, epoxy acrylate, and pure acrylic resin.

9. The separation method according to any one of claims 1 to 6, characterized in that The molecular weight of the reactive diluent is 250Da to 1000Da; and / or The functionality of the reactive diluent is 3 to 6.

10. The separation method according to any one of claims 1 to 6, characterized in that The reactive diluent is at least one of pentaerythritol triacrylate, pentaerythritol tetraacrylate, trimethylolpropane triacrylate, polydipentaerythritol hexaacrylate and ditrimethylolpropane tetraacrylate.

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