Method for detecting concentration of residual monomer in (methyl) acrylic resin

Abstract

The invention provides a method for detecting the concentration of residual monomers in (methyl) acrylic resin. According to the detection method, the residual monomers in the (methyl) acrylic resin can be accurately, rapidly and effectively separated, and the concentration of the residual monomers can be quantitatively analyzed; according to the detection method, a thermal analyzer is combined with a temperature programmed injection port-gas chromatography (PTV-GC), so that the influence of high-temperature decomposition of the (methyl) acrylic resin on the concentration of the residual monomer can be well reduced within a detection limit range, and a test structure of the concentration of the residual monomer is more accurate and stable.

Description

Technical Field

[0001] The present invention relates to the technical field of detection and analysis, and particularly relates to a method for detecting the concentration of residual monomers in (meth)acrylic resins. Background Art

[0002] (Meth)acrylic resins have advantages such as good acid resistance, ultraviolet resistance, and alkali resistance, and are widely used in many fields such as textiles, coatings, construction, adhesives, medical treatment, water treatment, and photoresists. Although (meth)acrylic resins have excellent performance and are safe, because most of their constituent monomers have strong irritation or corrosiveness, if they remain in the polymer product, they will not only affect the quality of the final product, but also pose potential safety hazards. For example, the content of residual monomers in the (meth)acrylic resin used in photoresists has a direct relationship with the lithography performance. Therefore, accurate detection of the content of residual monomers in (meth)acrylic resins is of great significance for the quality control of (meth)acrylic resins. Summary of the Invention

[0003] The inventors of the present application found through research that there are many types of (meth)acrylic resins, and a small amount of monomers that did not participate in the polymerization reaction remain in the (meth)acrylic resin during the polymerization process. However, there is no unified national standard for the detection of the concentration of residual monomers in (meth)acrylic resins. In many patent documents, the determination of the concentration of residual monomers in (meth)acrylic resins mostly uses high-performance liquid chromatography, gas chromatography, and redox titration. Among them, the determination limit of the redox titration method is relatively large, the sensitivity is low, and the operation is relatively cumbersome. Some (meth)acrylic resins have no strong ultraviolet absorption for the residual monomers, resulting in greater interference from the matrix and impurities when using high-performance liquid chromatography for determination. In comparison, gas chromatography is more suitable for determining the concentration of residual monomers in volatile (meth)acrylic resins.

[0004] Since (meth)acrylic resins have various forms such as aqueous solutions, emulsions, and solids, the matrix is relatively complex. In addition, the thermal decomposition temperature of (meth)acrylic resins usually varies within the temperature range of 150°C to 500°C. Therefore, for the detection of residual monomers, in addition to considering the boiling point of the target component, the chemical properties of the polymer also need to be considered. For example, when using the traditional gas chromatography method for detection, a single inlet temperature is relatively limited for the measurement of (meth)acrylic resins, and there are also disadvantages such as large interference and inability to confirm during the detection process. When using the ordinary gas chromatography-gas constant temperature injection mode, too high a temperature will cause the decomposition of (meth)acrylic resins, thus affecting the test results of residual monomers; too low a temperature will result in poor test stability and low repeatability. Therefore, it is necessary to develop an accurate, reliable, and sensitive method for determining the concentration of residual monomers in (meth)acrylic resins.

[0005] In order to improve the deficiencies of the prior art, the present invention provides a method for detecting the residual monomer concentration in a (meth)acrylic resin. The detection method effectively controls the decomposition of monomers in the (meth)acrylic resin by selecting a programmed inlet temperature, thereby achieving accurate and efficient testing of the residual monomer concentration in the (meth)acrylic resin. The detection method is characterized by being accurate, reliable, highly sensitive, and having good stability of test results.

[0006] In the present invention, the "(meth)acrylic resin" refers to a resin having a (meth)acrylic backbone. There is no particular limitation on the (meth)acrylic resin. For example, it can be a polymer of (meth)acrylic acid-based monomers such as (meth)acrylic acid and (meth)acrylate, or a copolymer of (meth)acrylic acid-based monomers and other monomers (such as polyethylene glycol monomethyl ether, polyethylene glycol monoethyl ether, or acrylonitrile).

[0007] In the present invention, the "(meth)acrylic acid" refers to "methacrylic acid" and / or "acrylic acid".

[0008] In the present invention, the "residual monomers in the (meth)acrylic resin" refers to the monomers that did not participate in the polymerization reaction during the polymerization process and remained in the polymer.

[0009] The object of the present invention is achieved by the following technical solutions:

[0010] A method for detecting the residual monomer concentration in a (meth)acrylic resin, the detection method comprising the following steps:

[0011] 1) Detect a solid (meth)acrylic resin sample to be tested in a thermal analyzer to obtain a thermogravimetric curve, and obtain the initial pyrolysis temperature T1 °C of the (meth)acrylic resin according to the thermogravimetric curve;

[0012] 2) Prepare the (meth)acrylic resin sample to be tested into a (meth)acrylic resin solution to be tested, and detect the (meth)acrylic resin solution to be tested in a gas chromatograph to obtain the areas of the chromatographic peaks of each residual monomer in the (meth)acrylic resin solution to be tested; determine the concentration of the residual monomers in the (meth)acrylic resin to be tested according to the linear mapping relationship between the area and concentration of the chromatographic peaks of the residual monomer standards and the areas of the chromatographic peaks of each residual monomer in the (meth)acrylic resin solution to be tested; wherein, the inlet temperature of the gas chromatograph is programmed; the programmed inlet temperature method is to hold for a period of time (such as 20 - 30 min) at (T1 - 20) °C to T1 °C, and then increase the temperature at a heating rate of 100 - 200 °C / min to 260 - 300 °C, and hold for a period of time (such as 5 - 20 min) at 260 - 300 °C.

[0013] According to an embodiment of the present invention, the injection port is programmed to heat at (T1-10) ° C ~ T1 ° C for 20-25 minutes, then heated to 270-290 ° C at a heating rate of 120-180 ° C / min, and kept at 270-290 ° C for 8-15 minutes.

[0014] Illustratively, the injection port is programmed to heat at T1°C for 20 minutes, then heated to 280°C at a heating rate of 150°C / min, and kept at 280°C for 10 minutes.

[0015] According to an embodiment of the present invention, in step 1), the thermal analyzer is a thermal analyzer known in the art for testing the thermal decomposition temperature of solid samples, for example, a STA6000 thermal analyzer.

[0016] According to an embodiment of the present invention, in step 1), the test temperature range of the thermal analyzer is 30°C-600°C, and the heating rate is 5-20°C / min, such as 10-15°C / min.

[0017] According to an embodiment of the present invention, in step 1), if the (meth)acrylic resin sample to be tested is in liquid form, a dry solid (meth)acrylic resin sample to be tested is obtained by solvent precipitation and drying.

[0018] According to an embodiment of the present invention, in step 2), the solvent selected for the gas chromatograph is chromatographic grade acetone; and the material of the chromatographic column of the gas chromatograph is a quartz capillary column.

[0019] According to an embodiment of the present invention, in step 2), the gas chromatograph is a chromatograph known in the art that can detect residual monomers in (meth)acrylic resin.

[0020] In a preferred embodiment of the present invention, in step 2), the chromatographic conditions of the gas chromatograph meet the following requirements:

[0021] Chromatographic column: DB-624UI;

[0022] Carrier gas: nitrogen; injection volume: 1.0 μL;

[0023] Carrier gas flow rate: 2.0-2.5 mL / min; split ratio: 20:1;

[0024] Detector temperature: 250-300°C;

[0025] Tail blow flow rate: 30~40mL / min;

[0026] Air flow rate: 350-400 mL / min;

[0027] Hydrogen flow rate: 30 - 40 mL / min;

[0028] The column oven conditions are as follows: hold at 50 - 80 °C for 3 min, then increase the temperature to 250 - 280 °C at a heating rate of 10 - 15 °C / min and hold for 10 - 15 min.

[0029] In a preferred embodiment of the present invention, in step 2), the chromatographic conditions of the gas chromatograph satisfy:

[0030] Chromatographic column: HP-WAX;

[0031] Carrier gas: helium; injection volume: 1.0 μL;

[0032] Carrier gas flow rate: 1.5 - 2.0 mL / min; split ratio: 10:1;

[0033] Detector temperature: 250 - 300 °C;

[0034] Make-up gas flow rate: 30 - 40 mL / min;

[0035] Air flow rate: 350 - 400 mL / min;

[0036] Hydrogen flow rate: 30 - 40 mL / min;

[0037] The column oven conditions are as follows: hold at 50 - 80 °C for 1 min, then increase the temperature to 250 - 280 °C at a heating rate of 10 - 15 °C / min and hold for 15 - 20 min.

[0038] According to the embodiment of the present invention, in step 2), the linear mapping relationship between the area and concentration of the chromatographic peak of the residual monomer standard satisfies the fitting linear equation R 2 ≥ 0.999.

[0039] According to the embodiment of the present invention, in step 2), the linear mapping relationship between the area and concentration of the chromatographic peak of the residual monomer standard is obtained by the following method:

[0040] a) Prepare a series of mixed standard solutions of residual monomers with different mass concentrations as standard solutions;

[0041] b) Inject the standard solution obtained in step a) under the above chromatographic conditions for determination, and record the peak area; use the mass concentration (mg / L) of the standard as the abscissa and the peak area (y) as the ordinate to plot a standard curve, which is the linear mapping relationship between the area and mass concentration of the chromatographic peak of the residual monomer standard.

[0042] According to an embodiment of the present invention, in step a), during the preparation of the standard solution, a residual monomer with a purity ≥ 99% is selected.

[0043] According to an embodiment of the present invention, in step a), the different mass concentrations can be 100 mg / L, 50 mg / L, 20 mg / L, 10 mg / L, and 5 mg / L.

[0044] According to an embodiment of the present invention, in step 2), the (meth)acrylic resin solution to be tested is prepared by the following method: Weigh a certain amount of the (meth)acrylic resin to be tested, dissolve it with acetone, and make up to the mark to obtain the (meth)acrylic resin solution to be tested.

[0045] According to an embodiment of the present invention, in step 2), the (meth)acrylic resin solution to be tested is preferably passed through a filter membrane with a size of 0.22 μm before entering the gas chromatography. The purpose of this operation is to avoid introducing impurity particle components into the gas chromatography and affecting the accuracy of the test results.

[0046] According to an embodiment of the present invention, the residual monomers in the (meth)acrylic resin include, but are not limited to, at least one of methyl methacrylate (MMA), ethyl methacrylate (EMA), allyl methacrylate (AMA), n-butyl methacrylate (n-BMA), isobutyl methacrylate (i-BMA), cyclohexyl methacrylate (CHMA), lauryl methacrylate (LMA), 3-methacryloyl-4-butyrolactone (β-GBLMA), isobornyl methacrylate (IBOMA), 1-ethylcyclopentyl methacrylate (ECPMA), 2-carboxy-4-norbornanolide-5-methyl acrylate (MNL), 2-hydroxyethyl methacrylate (HEMA), glycidyl methacrylate (GMA), 1-butoxyethyl methacrylate (BEMA), 1-methyl-1-cyclohexyl isobutyrate (MCHMA), and diethylaminohexyl methacrylate (DEAM).

[0047] Advantages of the present invention:

[0048] The present invention provides a method for detecting the concentration of residual monomers in a (meth)acrylic resin. The detection method can accurately and quickly separate the residual monomers in the (meth)acrylic resin effectively and quantitatively analyze the concentration of the residual monomers; the detection method combines a thermal analyzer with programmed temperature vaporizer-gas chromatography (PTV-GC), which can well reduce the influence of the high-temperature decomposition of the (meth)acrylic resin on the concentration of the residual monomers within the detection limit range, making the test results of the concentration of the residual monomers more accurate and stable. Description of the drawings

[0049] Figure 1 Thermogravimetric curve chromatogram of the methacrylic resin provided in Example 1 of the present invention.

[0050] Figure 2 Variation trend of the peak area of residual monomers in the methacrylic resin provided in Example 2 of the present invention with the inlet temperature.

[0051] Figure 3 Chromatogram of the residual monomer standard provided in Example 3 of the present invention.

[0052] Figure 4 Chromatogram of the methacrylic resin provided in Example 4 of the present invention. Detailed Description of the Specific Embodiments

[0053] The detection method of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only for illustrative and explanatory purposes of the present invention, and should not be construed as limiting the protection scope of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0054] The experimental methods used in the following embodiments are all conventional methods unless otherwise specified; the reagents, materials, etc. used in the following embodiments can all be obtained from commercial channels unless otherwise specified.

[0055] To introduce the detection method of the residual monomer concentration in the (meth)acrylic resin provided by the present invention more clearly and in detail, the present invention will be further described below in conjunction with specific embodiments. The embodiments of the present invention will test the concentrations of 6 residual monomers, namely MMA, EMA, HEMA, GMA, BEMA, and BMA, in the methacrylic resin. This test method is also applicable to the test of the concentrations of the remaining residual monomers. The experimental methods used are all conventional methods unless otherwise specified.

[0056] The methacrylic resin used in the following embodiments is the methacrylic resin produced in the same batch.

[0057] The model of the gas chromatograph used in the following embodiments is Shimadzu GC-2010Pro, and the detector is an FID detector. The chromatographic conditions for gas chromatography are as follows:

[0058] Chromatographic column: DB-624UI, specification 30m × 0.32mm × 1.8μm;

[0059] Carrier gas: nitrogen; injection volume: 1.0 μL;

[0060] Carrier gas flow rate: 2.0 mL / min; split ratio: 20:1;

[0061] Detector temperature: 300 °C;

[0062] Makeup gas flow rate: 30 mL / min;

[0063] Air flow rate: 400 mL / min;

[0064] Hydrogen flow rate: 40 mL / min;

[0065] The column oven heats the chromatographic column by means of programmed temperature rise. The specific operating conditions for programmed temperature rise are: hold at 50 °C for 3 min, and then increase the temperature to 280 °C at a rate of 10 °C / min and hold for 10 min.

[0066] Example 1

[0067] Precipitate and dry the liquid methyl methacrylate resin sample with n-hexane to obtain a dry solid methyl methacrylate resin sample. Turn on the STA6000 thermal analyzer and stabilize for 30 min; set the temperature rise conditions of the thermal analyzer to 30 °C - 600 °C, with a temperature rise rate of 10 °C / min; place 5.0 mg of the dry solid methyl methacrylate resin sample on the sample weighing pan of the thermal analyzer for test analysis. After the test analysis is completed, a Figure 1 thermogravimetric curve as shown Figure 1 is obtained, where the abscissa in Figure 1 represents temperature, with the unit of °C,

[0068] From Figure 1 the thermogravimetric curve, it can be seen that the weight of the methyl methacrylate resin to be measured gradually decreases from 150 °C to 170 °C until the temperature reaches 450 °C and then stops decreasing, at which time the resin weight is zero. It can be concluded that the methyl methacrylate resin to be measured starts to decompose at a temperature of 150 °C (i.e., T1 °C). Therefore, when detecting the concentration of residual monomers in this methyl methacrylate resin, the inlet temperature of the gas chromatograph should be ≤ 150 °C preferably.

[0069] Example 2

[0070] Weigh 0.5 g of methyl methacrylate resin, place it in a 10 mL centrifuge tube, and make up the volume to 10 mL with acetone. Ultrasonic it and vortex mix it evenly to obtain a methyl methacrylate resin solution to be measured with a concentration of 50 mg / mL; filter the methyl methacrylate resin solution to be measured through a 0.22 μm organic microporous membrane into a disposable injection vial to prepare a sample solution to be measured.

[0071] The prepared sample solution to be measured was detected by gas chromatography. Among them, the inlet temperature of the gas chromatography was set at a constant inlet temperature. Specifically, the constant inlet temperatures were set as: 100 °C, 120 °C, 150 °C, 170 °C, 180 °C, 200 °C, and 220 °C; the chromatographic peak areas of each residual monomer in the methacrylic resin under different inlet temperature conditions were measured by gas chromatography, and the results are shown in Table 1 and Figure 2 as shown below.

[0072] Table 1 Chromatographic peak areas of each residual monomer in methacrylic resin under different inlet temperature conditions in Example 2

[0073]

[0074] From Table 1 and Figure 2 it can be concluded that during the gas chromatography detection of the six residual monomers in the methacrylic resin, when the inlet temperature of the gas chromatograph is set below 150 °C, the test results (peak areas) of the residual monomers are relatively stable. When the inlet temperature of the gas chromatograph is set above 150 °C, as the inlet temperature increases, the peak areas of the residual monomers also increase. This is because as the inlet temperature increases, the injected methacrylic resin will decompose accordingly, and the decomposition products generated will affect the determination of the residual monomer concentration.

[0075] Combined with the test results of the thermal analyzer in Example 1, it can be analyzed that the optimal inlet temperature of the gas chromatograph is set at 100 °C to 150 °C. To increase the vaporization degree of the sample and ensure the repeatability and accuracy of the sample, the preferred inlet temperature is 130 - 150 °C.

[0076] Example 3

[0077] Weigh 100.0 mg of pure substances of MMA, EMA, BMA, HEMA, GMA, and BEMA with a purity of ≥99% into a 100 mL graduated volumetric flask, dissolve them with acetone, and make up the volume to the mark. A mixed standard stock solution with a monomer concentration of 1000 mg / L is prepared; according to the operation method in Table 2, take different volumes of the mixed standard stock solution and make up the volume to the mark with acetone, then a series of mixed standard solutions of residual monomers with gradient mass concentrations can be prepared.

[0078] Table 2 Preparation of a series of mixed standard solutions of residual monomers with gradient mass concentrations

[0079] Concentration Preparation operation 100 mg / L Transfer 5 mL of the 1000 mg / L mixed standard stock solution to a 50 mL volumetric flask and make up the volume with acetone 50 mg / L Transfer 5 mL of the 1000 mg / L mixed standard stock solution to a 100 mL volumetric flask and make up the volume with acetone 20 mg / L Transfer 10 mL of the 50 mg / L mixed standard stock solution to a 25 mL volumetric flask and make up the volume with acetone 10 mg / L Transfer 10 mL of the 50 mg / L mixed standard solution to a 50 mL volumetric flask and make up the volume with acetone 5 mg / L Transfer 10 mL of the 50 mg / L mixed standard solution to a 100 mL volumetric flask and make up the volume with acetone

[0080] The mixed standard solutions of 5 groups of residual monomers with different mass concentrations prepared in Table 2 were detected by gas chromatography. Among them, the inlet temperature of the gas chromatography was the PTV inlet temperature. Specifically, the PTV inlet temperature was set as follows: keep warm at 150 °C for 20 min, then increase the temperature to 280 °C at a heating rate of 150 °C / min, and keep warm at 280 °C for 10 min.

[0081] Figure 3 Figure 4 is the chromatogram of the standard solutions of 6 residual monomers. Table 3 shows the test results of the retention time, tailing factor and resolution of 6 residual monomers; Table 4 shows the mass concentration and corresponding peak area of the mixed standard solution of 6 residual monomers; Table 5 shows the linear fitting equation and correlation coefficient.

[0082] Table 3 Gas chromatography test results of 6 residual monomers (including retention time, tailing factor and resolution)

[0083]

[0084] Table 4 Mass concentration and corresponding peak area of the mixed standard solution of 6 residual monomers

[0085]

[0086] Table 5 Linear fitting equation and correlation coefficient

[0087]

[0088] It can be seen from Table 3, Table 4 and Table 5 above that the detection method used in Example 3 can make the resolution between residual monomers reach at least 7.511 (the national standard requirement for resolution > 1.5); the tailing factors are all around 1, and the peak shapes are symmetrical; the linear correlation coefficients are all above 0.999. According to the requirements of "GB / T 27417-2017", this method meets the detection requirements for the concentration of residual monomers in (meth)acrylic resins.

[0089] Example 4

[0090] Weigh 0.5 g of methacrylic resin, place it in a 10 mL centrifuge tube, and make up the volume to 10 mL with acetone. After ultrasonic treatment, vortex and mix it to obtain a methacrylic resin solution to be tested with a concentration of 50 mg / mL; filter the methacrylic resin solution to be tested through a 0.22 μm organic microporous membrane into a disposable injection vial to prepare a sample solution to be tested.

[0091] The prepared sample solution to be tested is detected by gas chromatography. Among them, the inlet temperature of the gas chromatography uses the PTV inlet temperature. Specifically, the PTV inlet temperature is set as follows: keep the temperature at 150 °C for 20 min, then increase the temperature to 280 °C at a heating rate of 150 °C / min, and keep the temperature at 280 °C for 10 min. The gas chromatogram obtained by detecting the prepared sample solution to be tested by gas chromatography is as shown in Figure 4 shown, and the test result data is shown in Table 6.

[0092] Table 6 Detection results of residual monomers in the methacrylic resin of Example 4

[0093]

[0094] It can be seen from Table 6 above that the minimum resolution of the chromatographic peaks of the six residual monomers MMA, EMA, HEMA, GMA, BEMA, and BMA in the methacrylic resin to be tested is 3.639 (the national standard requirement for resolution > 1.5), indicating that a good separation effect has been achieved, and the retention time of the monomer peak is very close to the monomer retention time of the standard product solution. Thus, it can be seen that the detection method for the concentration of residual monomers in the methacrylic resin provided in this example is not affected by other mixed impurities in the solution to be tested, has good detection stability, and high accuracy.

[0095] Example 5

[0096] Prepare mixed standard solutions of residual monomers at three concentrations of low, medium, and high within the linear range according to the method of Example 3, and use the gas chromatography conditions in Example 3 to perform three repeated detections on the mixed standard solutions of residual monomers with different mass concentrations. Substitute the peak area of the target peak of the detection results into the standard curve to calculate the concentration, and calculate the coefficient of variation (Cv value) according to the following formula:

[0097]

[0098] where Cv is the coefficient of variation, S is the standard deviation, is the arithmetic mean.

[0099] The obtained results are shown in Table 7.

[0100] Table 7 Detection results of three repeated detections in Example ⑤

[0101]

[0102] As can be seen from Table 7, the coefficient of variation in the mixed standard solutions of residual monomers at low, medium, and high concentrations within the linear range all meet the requirements of the coefficient of variation in the national standard. According to the relevant requirements of "GB / T 27417-2017", it can be shown that the precision of the detection method provided in this embodiment meets the requirements.

[0103] Example 6

[0104] Weigh 0.5 g of methacrylic resin, place it in a 10 mL centrifuge tube, and make up the volume to 10 mL with acetone. After ultrasonic treatment, vortex and mix it evenly to obtain a methacrylic resin solution to be tested with a concentration of 50 mg / mL; filter the methacrylic resin solution to be tested through a 0.22 μm organic microporous membrane into a disposable injection vial to prepare a sample solution to be tested.

[0105] The prepared sample solution to be tested is detected by gas chromatography. Among them, the injection port temperature of the gas chromatography is set as:

[0106] Injection condition 1: Adopt a constant injection port temperature. Specifically, the constant injection port temperature is set as: keep the temperature at 150 °C for 25 min;

[0107] Injection condition 2: Adopt a PTV injection port temperature. Specifically, the PTV injection port temperature is set as: keep the temperature at 150 °C for 20 min, then increase the temperature to 280 °C at a heating rate of 150 °C / min, and keep the temperature at 280 °C for 10 min;

[0108] Injection condition 3: Adopt a constant injection port temperature. Specifically, the constant injection port temperature is set as: keep the temperature at 250 °C for 25 min (refer to the injection port temperature range of 250 - 300 °C given in "GB / T 32699-2016").

[0109] The sample is repeatedly detected 6 times, and the coefficient of variation (Cv value) of the sample is calculated. The analysis results are shown in Table 8.

[0110] Table 8 Detection results of 6 repeated detections in Example 6

[0111]

[0112] It can be concluded from Table 8 that when testing at the temperature of 250 - 300 °C given in "GB / T 32699-2016", the sample decomposes severely and the precision is poor. When using a low-temperature constant injection port for sample testing, due to the relatively low injection port temperature setting, the methacrylic resin is severely enriched in the injection port liner, resulting in an increase in the Cv of the measurement result and poor precision. Therefore, this standard constant temperature mode cannot meet the measurement requirements for this resin.

[0113] In summary, it can be seen that by selecting the inlet temperature with a programmed temperature increase, the decomposition of monomers in the (meth)acrylic resin can be effectively controlled, and accurate and efficient testing of the residual monomer concentration in the (meth)acrylic resin can be achieved. The detection method has the characteristics of accuracy, reliability, high sensitivity, and good stability of test results.

[0114] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for detecting the concentration of residual monomers in a (methyl)methacrylic resin, the method comprising the following steps: 1) testing a solid (meth)acrylic resin sample in a thermal analyzer to obtain a thermogravimetric curve, and determining the initial pyrolysis temperature T1° C. of the (meth)acrylic resin based on the thermogravimetric curve; 2) Prepare the (meth)acrylic resin sample to be tested into a (meth)acrylic resin solution to be tested, and detect the (meth)acrylic resin solution to be tested in a gas chromatograph to obtain the areas of the chromatographic peaks of each residual monomer in the (meth)acrylic resin solution to be tested; determine the concentration of the residual monomer in the (meth)acrylic resin to be tested according to the linear mapping relationship between the area and the concentration of the chromatographic peak of the residual monomer standard product and the areas of the chromatographic peaks of each residual monomer in the (meth)acrylic resin solution to be tested; wherein, The injection port temperature of the gas chromatograph is increased by injection port programming; the injection port programming method is to keep the temperature at (T1-20) ° C ~ T1 ° C for a period of time (for example, 20-30 minutes), then increase the temperature to 260-300 ° C at a heating rate of 100-200 ° C / min, and keep it at 260-300 ° C for a period of time (for example, 5-20 minutes).

2. The detection method according to claim 1, wherein The injection port is programmed to heat at (T1-10)°C to T1°C for 20-25 minutes, then heated to 270-290°C at a heating rate of 120-180°C / min, and kept at 270-290°C for 8-15 minutes.

3. The detection method according to claim 3, wherein, The injection port temperature was programmed to be kept at T1°C for 20 minutes, then heated to 280°C at a heating rate of 150°C / min, and kept at 280°C for 10 minutes.

4. The detection method according to any one of claims 1 to 3, wherein, In step 1), the test temperature range of the thermal analyzer is 30° C.-600° C., and the heating rate is 5-20° C. / min.

5. The detection method according to any one of claims 1-4, wherein, In step 2), the chromatographic conditions of the gas chromatograph meet the following conditions: Chromatographic column: DB-624UI; Carrier gas: nitrogen; injection volume: 1.0 μL; Carrier gas flow rate: 2.0-2.5 mL / min; split ratio: 20:1; Detector temperature: 250-300°C; Tail blow flow rate: 30~40mL / min; Air flow rate: 350-400 mL / min; Hydrogen flow rate: 30-40 mL / min; The column oven conditions were as follows: keeping at 50-80°C for 3 min, heating to 250-280°C at a heating rate of 10-15°C / min and keeping at that temperature for 10-15 min.

6. The detection method according to any one of claims 1-4, wherein, In step 2), the chromatographic conditions of the gas chromatograph meet the following conditions: Column: HP-WAX; Carrier gas: helium; injection volume: 1.0 μL; Carrier gas flow rate: 1.5-2.0 mL / min; split ratio: 10:1; Detector temperature: 250-300°C; Tail blow flow rate: 30~40mL / min; Air flow rate: 350-400 mL / min; Hydrogen flow rate: 30-40 mL / min; The column oven conditions were as follows: keep warm at 50-80°C for 1 min, increase the temperature to 250-280°C at a heating rate of 10-15°C / min and keep warm for 15-20 min.

7. The detection method according to any one of claims 1-6, wherein, In step 2), the linear mapping relationship between the area and concentration of the chromatographic peak of the residual monomer standard is obtained by the following method: a) preparing a series of mixed standard solutions of residual monomers with different mass concentrations as standard solutions; b) Inject the standard solution obtained in step a) under the above chromatographic conditions for determination, and record the peak area. Using the mass concentration (mg / L) of the standard as the abscissa and the peak area (y) as the ordinate, plot a standard curve, which is the linear mapping relationship between the area and the mass concentration of the chromatographic peak of the residual monomer standard. Preferably, in step a), the different mass concentrations are 100 mg / L, 50 mg / L, 20 mg / L, 10 mg / L, and 5 mg / L.

8. The detection method according to any one of claims 1-7, wherein, In step 2), the linear mapping relationship between the area and concentration of the chromatographic peak of the residual monomer standard satisfies the fitting linear equation R 2 ≥ 0.

999.

9. The detection method according to any one of claims 1-8, wherein, In step 2), the (meth)acrylic resin solution to be tested passes through a filter membrane with a size of 0.22 μm before entering the gas chromatography.

10. The detection method according to any one of claims 1-9, wherein, The residual monomers in the (meth)acrylic resin include, but are not limited to, at least one of methyl methacrylate (MMA), ethyl methacrylate (EMA), allyl methacrylate (AMA), n-butyl methacrylate (n-BMA), isobutyl methacrylate (i-BMA), cyclohexyl methacrylate (CHMA), lauryl methacrylate (LMA), 3-methacryloyl-4-butyrolactone (β-GBLMA), isobornyl methacrylate (IBOMA), 1-ethylcyclopentyl methacrylate (ECPMA), 2-carboxy-4-norbornanolide-5-methyl methacrylate (MNL), 2-hydroxyethyl methacrylate (HEMA), glycidyl methacrylate (GMA), 1-butoxyethyl methacrylate (BEMA), 1-methyl-1-cyclohexyl isobutyrate (MCHMA), and diethylaminohexyl methacrylate (DEAM).

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