Fast characterization method of oca photocuring rate

Abstract

The present application relates to the technical field of material detection, and especially relates to a rapid characterization method of OCA photocuring rate.The rapid characterization method of OCA photocuring rate can dynamically monitor the OCA photocuring rate by testing the content and change rate of the photoinitiator 651, the free radical quenching product benzil and methyl benzoate in the OCA system, and combining the monomer conversion rate; in addition, the photocuring end point can be further obtained, and the optimal curing time is obtained. The present application can realize rapid and high-sensitivity characterization of the whole curing reaction process by monitoring the by-product generated by free radical self-quenching, and the method does not need to use organic solvents, and is safe and environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of materials testing technology, and in particular to a rapid characterization method for the curing rate of OCA (Optical Carbon Acrylic Acid). Background Technology

[0002] Optical transparent adhesives (OCAs) have wide applications in flexible display devices. Ultraviolet (UV) curing technology, due to its high efficiency and environmental friendliness, is the most commonly used curing method in OCA synthesis. The UV curing rate is a key indicator for evaluating product quality. It is closely related to properties such as peel strength and weather resistance. Accurate UV curing rate testing can assess the adhesion between the OCA and the substrate, preventing debonding due to insufficient curing or aging of the substrate resin due to over-curing. Currently, the industry mainly uses traditional characterization methods such as viscosity analysis, thermal analysis, hardness analysis, and chemical solvent extraction solids content method for UV curing rate testing. Although these methods are relatively mature, they generally rely on changes in macroscopic physical properties for indirect evaluation, often making high-precision measurement difficult in the later stages of UV curing (especially when the UV curing rate exceeds 95%), thus presenting certain limitations.

[0003] In view of this, the present invention is hereby proposed. Summary of the Invention

[0004] The purpose of this invention is to provide a rapid characterization method for the curing rate of OCA. This invention can achieve rapid and highly sensitive characterization of the entire curing reaction process by monitoring the byproducts generated by the self-quenching of free radicals. Moreover, the method does not require the use of organic solvents, making it safe and environmentally friendly.

[0005] To achieve the above-mentioned objectives of this invention, this invention provides a rapid characterization method for the photocurability of OCA, comprising the following steps:

[0006] (a) Take at least two parallel samples of cured OCA to be tested and name them as the first sample; continue to photocur one of the first samples for a time t to obtain the second sample; t is 5~10 s;

[0007] (b) The first sample and the second sample were subjected to Py-GC / MS tests to obtain the total ion chromatogram and the m / z 77 ion chromatogram; the m / z 77 ion chromatogram of the second sample was normalized by the peak area of ​​2,6-di-tert-butyl-p-cresol in the m / z 77 ion chromatogram of the first sample, and then the peak areas of methyl benzoate, azobenzoyl and photoinitiator 651 in the normalized m / z 77 ion chromatogram of the second sample were obtained, and the by-product conversion rate Tr was calculated.

[0008] Where, Tr=

[0009] , , The peak areas of photoinitiator 651, methyl benzoate, and azobenzoyl are respectively shown in the m / z 77 ion chromatogram of the first sample. , , The peak areas of photoinitiator 651, methyl benzoate, and azobenzoic acid are respectively shown in the normalized m / z 77 ion chromatogram of the second sample.

[0010] The photocuring rate R of the cured OCA to be tested is obtained from Tr.

[0011] If Tr satisfies: 0.1%≤Tr<25%, obtain the peak area of ​​each monomer in the total ion flow spectrum of the first sample, and calculate the photocuring rate R of the cured OCA to be tested;

[0012] Where R=

[0013] The OCA to be tested contains n monomers, A i C represents the peak area of ​​the monomer. i The response factor of the monomer. The peak area of ​​2,6-di-tert-butyl-p-cresol in the m / z 77 ion chromatogram of the first sample is denoted as S, where S is the mass percentage of 2,6-di-tert-butyl-p-cresol in the OCA to be tested.

[0014] If Tr satisfies: 25% ≤ Tr < 40%, then the photocuring rate R of the cured OCA to be tested is calculated according to the following formula:

[0015] Tr=59.376×R 3 – 186.73×R 2 + 195.5×R – 67.754

[0016] If Tr satisfies: 40%≤Tr<45%, then the photocuring rate of the cured OCA to be tested is 100%.

[0017] The OCA to be tested includes a photocurable monomer, photoinitiator 651, and 2,6-di-tert-butyl-p-cresol; the content of photoinitiator 651 is 0.5 wt% to 3 wt%.

[0018] In the Py-GC / MS test, the thermal decomposition temperature was 280~300℃.

[0019] In a specific embodiment of the present invention, the characterization method further includes: taking at least two first samples and continuing to perform photocuring treatment for 2t and 3t respectively to obtain a third sample and a fourth sample;

[0020] The third and fourth samples were subjected to Py-GC / MS testing to obtain total ion chromatograms and m / z 77 ion chromatograms. The m / z 77 ion chromatograms of the third and fourth samples were normalized using the peak area of ​​2,6-di-tert-butyl-p-cresol in the m / z 77 ion chromatogram of the first sample. Then, the peak areas of methyl benzoate, azobenzoyl, and photoinitiator 651 in the normalized m / z 77 ion chromatograms of the third and fourth samples were obtained respectively, and the byproduct conversion rates Tr' and Tr'' were calculated.

[0021] Where Tr'= ,Tr''= ,

[0022] , , The peak areas of photoinitiator 651, methyl benzoate, and azobenzoic acid are respectively in the m / z 77 ion chromatogram of the third sample after normalization. , , The peak areas of photoinitiator 651, methyl benzoate, and azobenzoic acid are respectively in the m / z 77 ion chromatogram of the fourth sample after normalization.

[0023] When Tr' and Tr'' satisfy: 40%≤Tr'<45%, 40%≤Tr''<45%, and Tr'=Tr'', then the curing time t'~t'+t of the OCA to be tested is taken as the light curing endpoint; t' is the cured time of the first sample.

[0024] In a specific embodiment of the present invention, the content of 2,6-di-tert-butyl-p-cresol in the OCA to be tested is 0.1wt% to 0.5wt%.

[0025] In a specific embodiment of the present invention, the photocurable monomer includes at least one of butyl acrylate, isooctyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, isobornyl acrylate, and dimethacrylamide.

[0026] In a specific embodiment of the present invention, the response factor of butyl acrylate is 2.9, the response factor of isooctyl acrylate is 2.9, the response factor of hydroxyethyl acrylate is 2.9, the response factor of hydroxypropyl acrylate is 1.8, the response factor of isobornyl acrylate is 1.9, and the response factor of dimethacrylamide is 3.

[0027] In a specific embodiment of the present invention, the irradiation intensity in the photocuring process is the same as the irradiation intensity used for the cured OCA to be tested. Further, the irradiation intensity is 12~14 mW / cm². 2 .

[0028] In a specific embodiment of the present invention, the lysis time in the Py-GC / MS test is 10~30s.

[0029] In a specific embodiment of the present invention, in the Py-GC / MS test, the chromatographic column is HP-5MS; the split ratio is (100~200):1; the interface temperature is 280~300℃; the inlet temperature is 280~300℃; the GC temperature program is as follows: hold at 40℃ for 2 min, then increase the temperature to 300℃ at 20℃ / min, and then hold at 300℃ for 10 min.

[0030] In a specific embodiment of the present invention, in the m / z 77 ion chromatogram, the retention time of 2,6-di-tert-butyl-p-cresol is 9.895 min ± 0.1 min, the retention time of methyl benzoate is 6.881 min ± 0.1 min, the retention time of azobenzoyl is 11.711 min ± 0.1 min, and the retention time of photoinitiator 651 is 12.044 min ± 0.1 min.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] This invention, by monitoring the byproducts generated from the self-quenching of free radicals, can accurately assess the dynamic development of the photocuring rate and further monitor the endpoint of the curing reaction, achieving rapid characterization of the entire photocuring process. The characterization method of this invention does not use organic solvents, making it safe and environmentally friendly. Attached Figure Description

[0033] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0034] Figure 1 The Py-GC / MS total ion chromatogram of photoinitiator 651 provided in the embodiments of the present invention;

[0035] Figure 2 The mass spectrum of photoinitiator 651 provided in an embodiment of the present invention;

[0036] Figure 3m / z 77 ion chromatograms of OCA with different UV irradiation times provided in embodiments of the present invention;

[0037] Figure 4 A graph showing the relationship between the content of photoinitiator 651 and the duration of continued ultraviolet irradiation after curing of OCA, provided in an embodiment of the present invention.

[0038] Figure 5 A graph showing the relationship between the methyl benzoate content and the duration of continued ultraviolet irradiation of cured OCA, as provided in an embodiment of the present invention.

[0039] Figure 6 The graph shows the relationship between the benzoyl content and the duration of UV irradiation after curing of OCA, as provided in an embodiment of the present invention. Detailed Implementation

[0040] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0041] Existing methods for characterizing the photocurability of OCA generally rely on indirect evaluation based on changes in macroscopic physical properties, which often struggles to achieve high-precision measurements in the later stages of photocuring (especially when the photocurability exceeds 95%), thus presenting certain limitations. To address these issues, this invention proposes a rapid characterization method for the photocurability of OCA based on free radical quenching. Photoinitiator 651 (2,2-dimethoxy-2-phenylacetophenone) generates benzoyl and α,α-dimethoxybenzyl free radicals under ultraviolet light. Most benzoyl free radicals react with the double bonds in the acrylate monomer to form copolymers; a small number of benzoyl free radicals self-quench, forming azobenzoyl. The α,α-dimethoxybenzyl free radicals have lower reactivity with double bonds than benzoyl free radicals; some participate in the double bond reaction, while others further decompose to produce methyl benzoate and methyl free radicals.

[0042] In the middle and early stages of curing (the photo-curing rate R satisfies: 0% < R ≤ 90%), there are a large number of double bonds in the resin system. Benzoyl radicals and α,α-dimethoxybenzyl radicals generated under ultraviolet light simultaneously participate in double bond initiation, chain elongation, and chain termination reactions. The by-products benzil and methyl benzoate generated by radical quenching are very low. The conversion rate of photoinitiator 651 to the sum of these two by-products is 0.1% - 25%. In the later stage of curing (the photo-curing rate R satisfies: 90% < R < 100%), most of the double bonds in the resin system have reacted completely. Continuing ultraviolet light irradiation, due to the higher activity of benzoyl radicals, benzoyl radicals will preferentially continue to participate in addition reactions, while α,α-dimethoxybenzyl radicals will decompose more to produce methyl benzoate. The content of benzil changes little in this stage, and the content of methyl benzoate increases rapidly. The conversion rate of photoinitiator 651 to the sum of these two by-products is 25% - 40%. After curing is completed (the photo-curing rate R = 100%), the double bonds in the OCA system have completely reacted. Continuing ultraviolet light irradiation, the OCA system begins to age, and the by-products benzil and methyl benzoate will both increase rapidly linearly. The conversion rate of photoinitiator 651 to the sum of these two by-products in this stage is 40% - 45%. By testing the content and change rate of photoinitiator 651, the radical quenching products benzil and methyl benzoate in the OCA system, and combining with the conversion rate of the monomer, the photo-curing rate of OCA can be dynamically monitored; in addition, the photo-curing end point can be further obtained to obtain the optimal curing time.

[0043] The total ion current chromatogram and mass spectrum of photoinitiator 651 were tested by pyrolysis gas chromatography - mass spectrometry (Py - GC / MS), as shown respectively in Figure 1 and Figure 2 Shown. Take 99.3 parts by mass of isooctyl acrylate, add 0.2 parts by mass of 2,6 - di - tert - butyl - p - cresol and 0.5 parts by mass of photoinitiator 651 and mix them, and then carry out ultraviolet light irradiation treatment for different times t (0s, 20s, 40s, 60s, 120s, 180s). Through Py - GC / MS testing under the same conditions, the ion current chromatogram of m / z 77 was obtained, as shown in Figure 3As shown in the figure, the retention times of 6.881 min ± 0.1 min correspond to the peak times of methyl benzoate, 9.895 min ± 0.1 min to 2,6-di-tert-butyl-p-cresol, 11.711 min ± 0.1 min to azobenzoic acid, and 12.044 min ± 0.1 min to photoinitiator 651. With increasing light exposure time, the curing rate continuously increases, the content of photoinitiator 651 continuously decreases, the content of azobenzoic acid remains constant before increasing, and the content of methyl benzoate initially increases slowly before increasing rapidly. The cured OCA material (corresponding to the cured OCA sample obtained in step (1) of Example 3) was subjected to further ultraviolet irradiation, and Py-GC / MS tests were performed under the same conditions to obtain an m / z 77 ion chromatogram. The peak areas of photoinitiator 651, methyl benzoate, and benzoyl peroxide were plotted on the ordinate, and the duration of further ultraviolet irradiation was plotted on the abscissa. Figures 4-6 As shown in the figure, the content of photoinitiator 651 decreases linearly, the content of methyl benzoate increases linearly, and the content of azobenzoyl increases linearly.

[0044] In the early to mid-stages of curing, the photocuring rate is calculated by summing the conversion rates (Tr) of photoinitiator 651 to methyl benzoate and benzoyl peroxide. If Tr ≥ 0.1% and Tr < 25%, the photocuring rate can be obtained by calculating the acrylate monomer conversion rate. In the mid to late-stages of curing, if Tr ≥ 25% and Tr < 40%, the photocuring rate calculated based on the monomer conversion rate will have a large error. At this stage, the curing rate (x-axis) and Tr (y-axis) satisfy a relationship derived from a third-order polynomial curve obtained through fitting. Substituting Tr into the equation yields the photocuring rate. After curing is complete, Tr ≥ 40% and Tr < 45% and remains unchanged. By using different calculation methods for different stages, the photocuring rate and the photocuring endpoint of the sample can be obtained quickly.

[0045] Based on this, the present invention provides a rapid characterization method for the photocurability of OCA, comprising the following steps:

[0046] (a) Take at least two parallel samples of cured OCA to be tested and name them as the first sample; continue to photocur one of the first samples for a time t to obtain the second sample; t is 5~10 s;

[0047] (b) The first and second samples were subjected to Py-GC / MS tests to obtain the total ion chromatogram and the m / z 77 ion chromatogram; the m / z 77 ion chromatogram of the second sample was normalized by the peak area of ​​2,6-di-tert-butyl-p-cresol in the m / z 77 ion chromatogram of the first sample, and then the peak areas of methyl benzoate, azobenzoyl and photoinitiator 651 in the normalized m / z 77 ion chromatogram of the second sample were obtained, and the by-product conversion rate Tr was calculated.

[0048] Where, Tr=

[0049] , , The peak areas of photoinitiator 651, methyl benzoate, and azobenzoyl are respectively shown in the m / z 77 ion chromatogram of the first sample. , , The peak areas of photoinitiator 651, methyl benzoate, and azobenzoic acid are respectively shown in the normalized m / z 77 ion chromatogram of the second sample.

[0050] The photocuring rate R of the cured OCA to be tested is obtained from Tr.

[0051] If Tr satisfies: 0.1%≤Tr<25%, obtain the peak area of ​​each monomer in the total ion flow spectrum of the first sample, and calculate the photocuring rate R of the cured OCA to be tested;

[0052] Where R=

[0053] The OCA to be tested contains n monomers, where n is an integer ≥ 1, and A i C represents the peak area of ​​the monomer. i The response factor of the monomer. The peak area of ​​the characteristic ion of 2,6-di-tert-butyl-p-cresol in the m / z 77 ion chromatogram of the first sample is denoted as S, and S is the mass percentage of 2,6-di-tert-butyl-p-cresol in the OCA to be tested.

[0054] If Tr satisfies: 25% ≤ Tr < 40%, then the photocuring rate R of the cured OCA to be tested is calculated according to the following formula:

[0055] Tr=59.376×R 3 – 186.73×R 2 + 195.5×R – 67.754

[0056] If Tr satisfies: 40%≤Tr<45%, then the photocuring rate of the cured OCA to be tested is 100%.

[0057] The OCA to be tested includes a photocurable monomer, photoinitiator 651, and 2,6-di-tert-butyl-p-cresol; the content of photoinitiator 651 is 0.5 wt%~3 wt%.

[0058] In Py-GC / MS testing, the thermal decomposition temperature was 280~300℃.

[0059] In some implementations, the OCA to be tested refers to an uncured OCA system comprising a photocurable monomer, photoinitiator 651, and 2,6-di-tert-butyl-p-cresol. A cured OCA to be tested refers to an OCA to be tested that has been cured under an irradiation source at a certain irradiation intensity for a certain time t', where t' is not limited in specific time, for example, it can be 5 to 150 s.

[0060] In some embodiments, the content of photoinitiator 651 in the OCA to be tested is 0.5wt% to 3wt%, specifically it can be 0.5wt%, 0.8wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, or any combination thereof.

[0061] In some embodiments, the content of 2,6-di-tert-butyl-p-cresol in the OCA to be tested is 0.1 wt% to 0.5 wt%, specifically 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, or any combination thereof. 2,6-di-tert-butyl-p-cresol is introduced as an internal standard reference.

[0062] In some embodiments, the photocurable monomer includes at least one selected from butyl acrylate, isooctyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, isobornyl acrylate, and dimethacrylamide. OCA samples containing other photocurable monomers can also have their photocurability tested using the characterization methods of this invention.

[0063] In some implementations, the number of photocurable monomers n in the OCA to be tested is greater than or equal to 1, for example, it can be 1, 2, 4, 6, 8, 10 or any combination thereof, but is not limited thereto.

[0064] In some embodiments, the response factor of butyl acrylate is 2.9, the response factor of isooctyl acrylate is 2.9, the response factor of hydroxyethyl acrylate is 2.9, the response factor of hydroxypropyl acrylate is 1.8, the response factor of isobornyl acrylate is 1.9, the response factor of dimethacrylamide is 3, and the response factor of other unspecified photocurable monomers is 2.5.

[0065] In some implementations, the photocuring conditions for the cured OCA to be tested are not limited, such as the irradiation source including but not limited to ultraviolet mercury lamps, and the irradiation intensity including but not limited to 13±1mW / cm². 2 .

[0066] In some embodiments, the preparation of the cured OCA to be tested may include: mixing a photocurable monomer, photoinitiator 651, and 2,6-di-tert-butyl-p-cresol in a certain proportion to obtain the OCA to be tested; placing it in a light-transmitting container (such as a glass bottle) and heating it under a mercury lamp at 13±1 mW / cm². 2The OCA to be tested is cured by irradiation at a certain intensity for a certain time t', and then stored in the dark to obtain cured OCA. This is not to limit the preparation method of cured OCA, but only to provide an optional preparation method.

[0067] In some implementations, during the continued photocuring of the sample, the irradiation source and irradiation intensity are kept the same as the photocuring conditions of the already cured OCA to be tested.

[0068] In some implementations, in step (b), at least two first samples and at least two second samples can be taken for parallel experiments, and the average value is used to calculate the byproduct conversion rate Tr.

[0069] In some implementations, in step (b), the Py-GC / MS test is performed in a thermal pyrolysis-gas chromatography-mass spectrometry system.

[0070] In some implementations, the test conditions in Py-GC / MS testing include: a thermal decomposition temperature of 280~300℃, specifically a range of 280℃, 285℃, 290℃, 295℃, 300℃ or any combination thereof; and a decomposition time of 10~30s, specifically a range of 10s, 15s, 20s, 25s, 30s or any combination thereof.

[0071] In some implementations, the Py-GC / MS test uses an HP-5MS column; the split ratio is (100–200):1, specifically 100:1, 120:1, 150:1, 180:1, 200:1, or any combination thereof; the interface temperature is 280–300°C, specifically 280°C, 285°C, 290°C, 295°C, 300°C, or any combination thereof; and the inlet temperature is 280–300°C, specifically 280°C, 285°C, 290°C, 295°C, 300°C, or any combination thereof.

[0072] In some implementations, the GC temperature program for Py-GC / MS testing is as follows: hold at 40°C for 2 min, then increase the temperature to 300°C at a rate of 20°C / min, and then hold at 300°C for 10 min. Further, the sample mass in the Py-GC / MS testing is 0.1~0.5 mg.

[0073] Parameters not mentioned in the Py-GC / MS test are standard parameter settings.

[0074] In some embodiments, in the m / z 77 ion chromatogram, the retention time of 2,6-di-tert-butyl-p-cresol is 9.895 min ± 0.1 min, the retention time of methyl benzoate is 6.881 min ± 0.1 min, the retention time of azobenzoyl is 11.711 min ± 0.1 min, and the retention time of photoinitiator 651 is 12.044 min ± 0.1 min.

[0075] In some embodiments, the characterization method further includes: taking at least two first samples and continuing to photocuring them for 2t and 3t respectively to obtain a third sample and a fourth sample;

[0076] The third and fourth samples were subjected to Py-GC / MS analysis to obtain total ion chromatograms and m / z 77 ion chromatograms. The m / z 77 ion chromatograms of the third and fourth samples were normalized using the peak area of ​​2,6-di-tert-butyl-p-cresol in the m / z 77 ion chromatogram of the first sample. Then, the peak areas of methyl benzoate, azobenzoyl, and photoinitiator 651 in the normalized m / z 77 ion chromatograms of the third and fourth samples were obtained respectively, and the byproduct conversion rates Tr' and Tr'' were calculated.

[0077] Where Tr'= ,Tr''= ,

[0078] , , The peak areas of photoinitiator 651, methyl benzoate, and azobenzoic acid are respectively in the m / z 77 ion chromatogram of the third sample after normalization. , , The peak areas of photoinitiator 651, methyl benzoate, and azobenzoic acid are respectively in the m / z 77 ion chromatogram of the fourth sample after normalization.

[0079] When Tr' and Tr'' satisfy: 40%≤Tr'<45%, 40%≤Tr''<45%, and Tr'=Tr'', then the curing time t'~t'+t of the OCA to be tested is taken as the light curing endpoint; t' is the curing time of the first sample.

[0080] In practice, when characterizing the photocuring endpoint of the OCA under test, the OCA can be photocured for a certain time t', and then the test calculations can be performed according to the method described above. The photocuring time t' is adjusted until Tr' and Tr'' satisfy: 40%≤Tr'<45%, 40%≤Tr''<45%, and Tr'=Tr''; then the curing time t'~t'+t of the OCA under test is taken as the photocuring endpoint. Evaluating the photocuring endpoint of OCA can reduce the problem of excessive aging of OCA after curing.

[0081] The following embodiments further verify the accuracy and reliability of the testing method of the present invention.

[0082] Example 1

[0083] This embodiment provides a rapid characterization method for the photocurability of OCA, including the following steps:

[0084] (1) Weigh 90 parts by weight of butyl acrylate monomer, 9 parts by weight of isobornyl acrylate monomer, 0.5 parts by weight of 2,6-di-tert-butyl-p-cresol and 0.5 parts by weight of photoinitiator 651, add them to a 250 mL three-necked flask, purge with protective nitrogen for 5 min and mix well to obtain the OCA to be tested. Dispense 0.5 mL / bottle into two 2 mL glass vials, purge with nitrogen to remove air, tighten the caps and store in the dark;

[0085] When placed under an ultraviolet mercury lamp, the irradiation intensity is (13±1) mW / cm 2 The OCA sample was cured by irradiation for a certain period of time (40 s) to obtain a cured sample for testing. One of the cured OCA samples was placed under a mercury lamp with an irradiation intensity of (13±1) mW / cm². 2 Continue curing for 10 seconds to obtain the second sample.

[0086] (2) Weigh 0.3 mg of the solidified OCA sample and the second sample respectively, and perform Py-GC / MS testing to obtain the total ion chromatogram and the ion chromatogram at m / z 77. In the Py-GC / MS test, the pyrolysis temperature was set to 280℃, the pyrolysis time was 10 s; the column type was HP-5MS, and the GC temperature program was: 40℃ for 2 min, then increased to 300℃ at 20℃ / min, and then held at 300℃ for 10 min; the split ratio was 100:1; the interface temperature was 300℃, and the inlet temperature was 300℃. All samples were tested in parallel, and the average value of the results was taken.

[0087] The m / z 77 ion chromatogram of the second sample was normalized using the peak area of ​​2,6-di-tert-butyl-p-cresol (retention time 9.895 min ± 0.1 min) in the m / z 77 ion chromatogram of the cured OCA sample. Then, the peak areas of retention times of 6.881 min ± 0.1 min (corresponding to methyl benzoate), 11.711 min ± 0.1 min (corresponding to azobenzoyl), and 12.044 min ± 0.1 min (corresponding to photoinitiator 651) in the normalized m / z 77 ion chromatogram of the second sample were obtained. The byproduct conversion rate Tr was calculated according to the following formula.

[0088] Where, Tr=

[0089] , , The peak areas of photoinitiator 651, methyl benzoate, and azobenzoic acid are respectively shown in the m / z 77 ion chromatogram of the cured OCA sample to be tested. , , The peak areas of photoinitiator 651, methyl benzoate, and azobenzoic acid are respectively shown in the normalized m / z 77 ion chromatogram of the second sample.

[0090] The calculated Tr = 21.23%, which satisfies 0.1% ≤ Tr < 25%.

[0091] Then, based on the total ion chromatogram of the solidified OCA sample to be tested, the peak areas of each monomer (butyl acrylate and isobornyl acrylate) were obtained by integration. The peak area of ​​the characteristic ion of butyl acrylate was 209,124,829, with a response factor of 2.9, and the peak area of ​​isobornyl acrylate was 35,406,746, with a response factor of 1.9.

[0092] The photocuring rate R of the cured OCA to be tested is calculated according to the following formula;

[0093] Where R=

[0094] The OCA sample to be tested contains two monomers, A i C represents the peak area of ​​the monomer. i The response factor of the monomer. The peak area of ​​2,6-di-tert-butyl-p-cresol in the m / z 77 ion chromatogram of the cured OCA sample to be tested is S, where S is the mass percentage of 2,6-di-tert-butyl-p-cresol in the OCA to be tested. The value is 23,546,782, and S is 0.5%.

[0095] The calculated value is R = 1 - (209124829 × 2.9 + 35406746 × 1.9) / 23546782 × 0.5% = 85.69%.

[0096] Take 50g of the cured OCA sample obtained in step (1), add 200mL of ethyl acetate, extract at 60℃, filter, and vacuum dry at 50℃. The photocuring rate calculated by the chemical solvent extraction solid content method is 83.76%, which is too low. If the unreacted photoinitiator 651, 2,6-di-tert-butyl-p-cresol and some soluble dimer and trimer are deducted, the result is consistent, and the method is accurate.

[0097] Example 2

[0098] This embodiment provides a rapid characterization method for the photocurability of OCA, including the following steps:

[0099] (1) Weigh out 60 parts by weight of isooctyl acrylate, 5 parts by weight of isobornyl acrylate, 20 parts by weight of hydroxyethyl acrylate, 13.7 parts by weight of dimethylacrylamide, 0.3 parts by weight of 2,6-di-tert-butyl-p-cresol, and 1 part by weight of photoinitiator 651. Add them to a 250 mL three-necked flask, purge with protective nitrogen for 5 min and mix thoroughly to obtain the OCA to be tested. Dispense 0.5 mL / bottle into two 2 mL glass vials, purge with nitrogen to remove air, tighten the caps and store in the dark.

[0100] When placed under an ultraviolet mercury lamp, the irradiation intensity is (13±1) mW / cm 2 The OCA sample was cured by irradiation for a certain period of time (85 s) to obtain a cured sample for testing. One of the cured OCA samples was placed under a mercury lamp with an irradiation intensity of (13±1) mW / cm². 2 Continue curing for 8 seconds to obtain the second sample.

[0101] (2) Weigh 0.4 mg of the solidified OCA sample and the second sample respectively, and perform Py-GC / MS testing to obtain the total ion chromatogram and the ion chromatogram at m / z 77. In the Py-GC / MS test, the pyrolysis temperature was set to 290℃, the pyrolysis time was 15 s; the column type was HP-5MS, and the GC temperature program was: 40℃ for 2 min, then increased to 300℃ at 20℃ / min, and then held at 300℃ for 10 min; the split ratio was 150:1; the interface temperature was 290℃, and the inlet temperature was 290℃. All samples were tested in parallel, and the average value of the results was taken.

[0102] The m / z 77 ion chromatogram of the second sample was normalized using the peak area of ​​2,6-di-tert-butyl-p-cresol (retention time 9.895 min ± 0.1 min) in the m / z 77 ion chromatogram of the cured OCA sample. Then, the peak areas of retention times of 6.881 min ± 0.1 min (corresponding to methyl benzoate), 11.711 min ± 0.1 min (corresponding to azobenzoyl), and 12.044 min ± 0.1 min (corresponding to photoinitiator 651) in the normalized m / z 77 ion chromatogram of the second sample were obtained. The byproduct conversion rate Tr was calculated according to the following formula.

[0103] Where, Tr=

[0104] , , The peak areas of photoinitiator 651, methyl benzoate, and azobenzoic acid are respectively shown in the m / z 77 ion chromatogram of the cured OCA sample to be tested. , , The peak areas of photoinitiator 651, methyl benzoate, and azobenzoic acid are respectively shown in the normalized m / z 77 ion chromatogram of the second sample.

[0105] The calculated Tr = 38.11%, which satisfies 25% ≤ Tr < 40%.

[0106] At this stage, the curing rate R and Tr satisfy the following 3rd order polynomial curve equation relationship. Based on the 3rd order polynomial curve equation relationship, Tr is substituted into the equation to obtain the curing rate R.

[0107] Tr=59.376×R 3 – 186.73×R 2 + 195.5×R – 67.754

[0108] The calculated value is R = 99.14%.

[0109] Take 50g of the cured OCA sample obtained in step (1), add 200mL of ethyl acetate, extract at 60℃, filter and dry under vacuum at 50℃. The photocuring rate calculated by the chemical solvent extraction solid content method is 96.7%. The test result of this method is too small, and there are soluble dimers, trimers and other substances that cannot be calculated. Therefore, the chemical solvent extraction solid content method is not applicable to the calculation of the curing rate near the curing endpoint.

[0110] Example 3

[0111] This embodiment provides a rapid characterization method for the photocurability of OCA, including the following steps:

[0112] (1) Weigh out 50 parts by weight of butyl acrylate monomer, 30 parts by weight of hydroxyethyl acrylate monomer, 17.7 parts by weight of dimethylacrylamide monomer, 0.3 parts by weight of 2,6-di-tert-butyl-p-cresol and 2 parts by weight of photoinitiator 651, add them to a 250mL three-necked flask, purge with protective nitrogen for 5min and mix well to obtain the OCA to be tested. Dispense 0.5mL / bottle into two 2mL glass vials, purge with nitrogen to remove air, tighten the caps and store in the dark;

[0113] When placed under an ultraviolet mercury lamp, the irradiation intensity is (13±1) mW / cm 2 The OCA sample was cured by irradiation for a certain period of time (120 s) to obtain a cured sample for testing. One of the cured OCA samples was placed under a mercury lamp with an irradiation intensity of (13±1) mW / cm². 2 Continue curing for 9 seconds to obtain the second sample.

[0114] (2) Weigh 0.45 mg of the solidified OCA sample and the second sample respectively, and perform Py-GC / MS testing to obtain the total ion chromatogram and the ion chromatogram at m / z 77. In the Py-GC / MS test, the pyrolysis temperature was set to 300℃, the pyrolysis time was 25 s; the column type was HP-5MS, and the GC temperature program was: 40℃ for 2 min, then increased to 300℃ at 20℃ / min, and then held at 300℃ for 10 min; the split ratio was 180:1; the interface temperature was 280℃, and the inlet temperature was 280℃. All samples were tested in parallel, and the average value of the results was taken.

[0115] The m / z 77 ion chromatogram of the second sample was normalized using the peak area of ​​2,6-di-tert-butyl-p-cresol (retention time 9.895 min ± 0.1 min) in the m / z 77 ion chromatogram of the cured OCA sample. Then, the peak areas of retention times of 6.881 min ± 0.1 min (corresponding to methyl benzoate), 11.711 min ± 0.1 min (corresponding to azobenzoyl), and 12.044 min ± 0.1 min (corresponding to photoinitiator 651) in the normalized m / z 77 ion chromatogram of the second sample were obtained. The byproduct conversion rate Tr was calculated according to the following formula.

[0116] Where, Tr=

[0117] , , The peak areas of photoinitiator 651, methyl benzoate, and azobenzoic acid are respectively shown in the m / z 77 ion chromatogram of the cured OCA sample to be tested. , , The peak areas of photoinitiator 651, methyl benzoate, and azobenzoic acid are respectively shown in the normalized m / z 77 ion chromatogram of the second sample.

[0118] The calculated Tr = 40.8%, which satisfies 40% ≤ Tr < 45%.

[0119] The photocuring rate R of the cured OCA to be tested is 100%.

[0120] Take 50g of the cured OCA sample obtained in step (1), add 200mL of ethyl acetate, extract at 60℃, filter and dry under vacuum at 50℃. The photocuring rate calculated by the chemical solvent extraction solid content method is 99.1%. The test result of this method is too small, and there are soluble dimers, trimers and other substances that cannot be calculated. Therefore, the chemical solvent extraction solid content method is not applicable to the calculation of the curing rate of fully cured samples.

[0121] Example 4

[0122] This embodiment provides a rapid characterization method for OCA photocurability and photocuring endpoint, including the following steps:

[0123] (1) Weigh out 50 parts by weight of butyl acrylate, 20 parts by weight of hydroxypropyl acrylate, 20 parts by weight of isooctyl acrylate, 8.8 parts by weight of dimethacrylamide, 0.4 parts by weight of 2,6-di-tert-butyl-p-cresol, and 0.8 parts by weight of photoinitiator 651. Add them to a 250 mL three-necked flask, purge with protective nitrogen for 5 min and mix thoroughly to obtain the OCA to be tested. Dispense 0.5 mL / bottle into four 2 mL glass vials, purge with nitrogen to remove air, tighten the caps and store in the dark.

[0124] When placed under an ultraviolet mercury lamp, the irradiation intensity is (13±1) mW / cm 2 The samples were cured by irradiation for a certain period of time (55 s) to obtain cured OCA samples for testing. Three of the cured OCA samples were placed under a UV mercury lamp with an irradiation intensity of (13±1) mW / cm². 2 The samples were cured for 10 s, 20 s, and 30 s respectively to obtain the second, third, and fourth samples.

[0125] (2) Weigh 0.35 mg of each of the solidified OCA sample to be tested, the second sample, the third sample, and the fourth sample, and perform Py-GC / MS tests to obtain the total ion chromatogram and the ion chromatogram at m / z 77. In the Py-GC / MS test, the pyrolysis temperature was set to 300℃, the pyrolysis time was 20 s; the column type was HP-5MS, and the GC temperature program was: 40℃ for 2 min, then increased to 300℃ at 20℃ / min, and then held at 300℃ for 10 min; the split ratio was 150:1; the interface temperature was 300℃, and the inlet temperature was 300℃. All samples were tested in parallel, and the average value of the results was taken.

[0126] The m / z 77 ion chromatograms of the four samples were normalized using the peak area of ​​2,6-di-tert-butyl-p-cresol (retention time 9.895 min ± 0.1 min) in the m / z 77 ion chromatogram of the cured OCA sample. Then, the peak areas of retention times of 6.881 min ± 0.1 min (corresponding to methyl benzoate), 11.711 min ± 0.1 min (corresponding to azobenzoyl), and 12.044 min ± 0.1 min (corresponding to photoinitiator 651) in the m / z 77 ion chromatograms of the cured OCA sample, the normalized second sample, the third sample, and the fourth sample were obtained respectively. The byproduct conversion rate Tr was calculated according to the following formula.

[0127] Where, Tr=

[0128] , , The peak areas of photoinitiator 651, methyl benzoate, and azobenzoic acid are respectively shown in the m / z 77 ion chromatogram of the cured OCA sample to be tested. , , The peak areas of photoinitiator 651, methyl benzoate, and azobenzoic acid are respectively shown in the normalized m / z 77 ion chromatogram of the second sample.

[0129] The calculated Tr = 38.25%, which satisfies 25% ≤ Tr < 40%.

[0130] At this stage, the curing rate R and Tr satisfy the following 3rd order polynomial curve equation relationship. Based on the 3rd order polynomial curve equation relationship, Tr is substituted into the equation to obtain the curing rate R.

[0131] Tr=59.376×R 3 – 186.73×R 2 + 195.5×R – 67.754

[0132] The calculated value is R = 99.70%.

[0133] (3) Calculate the by-product conversion rates Tr' and Tr'' according to the following formula;

[0134] Where Tr'= ,Tr''= ,

[0135] , , The peak areas of photoinitiator 651, methyl benzoate, and azobenzoic acid are respectively the peak areas of photoinitiator 651, methyl benzoate, and azobenzoic acid in the m / z 77 ion chromatogram of the third sample after normalization in step (2). , , The peak areas of photoinitiator 651, methyl benzoate, and azobenzoic acid are respectively the peak areas of the fourth sample after normalization in step (2) at m / z 77 ion chromatogram.

[0136] The calculation yields Tr'=40.3% and Tr''=40.3%;

[0137] Tr' and Tr'' satisfy: 40%≤Tr'<45%, 40%≤Tr''<45%, and Tr'=Tr'', indicating that the second sample has been cured and the photocuring rate of the second sample is 100%. Based on this, for the OCA sample in this embodiment, the curing time t'~t'+t (55s~55s+10s) is taken as the photocuring endpoint of the OCA to be tested.

[0138] Comparative Example 1

[0139] Comparative Example 1 follows the characterization method of Example 1, except that: in step (1), 2,6-di-tert-butyl-p-cresol is not added; in step (2), no normalization is performed, and the peak areas of retention times of 6.881 min ± 0.1 min (corresponding to methyl benzoate), 11.711 min ± 0.1 min (corresponding to azobenzoyl), and 12.044 min ± 0.1 min (corresponding to photoinitiator 651) in the ion chromatogram of the cured OCA sample and the second sample at m / z 77 are directly obtained. The peak areas of each peak after normalization in Example 1 are replaced by the peak areas after normalization. The calculated Tr = 78.86% > 45%, and the photocuring rate of the cured OCA sample cannot be further calculated.

[0140] Comparative Example 2

[0141] Comparative Example 2 uses the same characterization method as Example 1, except that in step (2), the thermal decomposition temperature is set to 450°C in the Py-GC / MS test;

[0142] At this temperature, 2,6-di-tert-butyl-p-cresol also undergoes cleavage. After normalization, the data has a large error, and the calculated Tr = 22.83%.

[0143] Based on the total ion chromatogram of the solidified OCA sample to be tested, the peak areas of the characteristic ions of each monomer (butyl acrylate and isobornyl acrylate) were obtained by integration. The peak area of ​​the characteristic ion of butyl acrylate was 732,467,145, and the peak area of ​​isobornyl acrylate was 956,393,267. The calculated R was 1 - (732,467,145 × 2.9 + 956,393,267 × 1.9) / 21,758,923 × 0.5% = 9.43%.

[0144] Compared to the 83.76% curing rate achieved by the chemical reagent extraction method in Example 1, the error is significant, and the photocuring rate of the sample cannot be accurately obtained. The main reason is that some of the polymerized monomers undergo chain scission reactions at this pyrolysis temperature, generating the original monomers.

[0145] Comparative Example 3

[0146] Comparative Example 3 follows the characterization method of Example 1, except that in step (1), the amount of photoinitiator 651 is 0.02 parts by weight.

[0147] Following the method of Example 1, , , , , All values ​​are 0, so Tr cannot be calculated. The photocuring rate of the cured OCA sample cannot be further calculated. This is mainly because the amount of photoinitiator 651 in the cured OCA sample is too small, and it has already reacted completely, while only a small portion of the monomers in the cured OCA sample have cured at this point.

[0148] The generation of free radicals, chain initiation, chain elongation, chain termination, and the production of byproducts through free radical self-quenching can reflect the progress of the curing reaction. This invention, by monitoring the byproducts generated through free radical self-quenching, can accurately assess the dynamic development of the photocuring rate and further monitor the endpoint of the curing reaction, achieving rapid and highly sensitive characterization of the entire photocuring process.

[0149] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A rapid characterization method for the photocurability of OCA, characterized in that, Includes the following steps: (a) Take at least two parallel samples of cured OCA to be tested and name them as the first sample; continue to photocur one of the first samples for a time t to obtain the second sample; t is 5~10 s; (b) Perform Py-GC / MS tests on the first sample and the second sample to obtain the total ion chromatogram and the m / z 77 ion chromatogram; The peak area of ​​2,6-di-tert-butyl-p-cresol in the m / z 77 ion chromatogram of the first sample was normalized to the m / z 77 ion chromatogram of the second sample. Then, the peak areas of methyl benzoate, azobenzoyl, and photoinitiator 651 in the normalized m / z 77 ion chromatogram of the second sample were obtained, and the byproduct conversion rate Tr was calculated. Where, Tr= , , The peak areas of photoinitiator 651, methyl benzoate, and azobenzoyl are respectively shown in the m / z 77 ion chromatogram of the first sample. , , The peak areas of photoinitiator 651, methyl benzoate, and azobenzoyl in the m / z 77 ion chromatogram of the second sample after normalization are respectively. The photocuring rate R of the cured OCA to be tested is obtained from Tr. If Tr satisfies: 0.1%≤Tr<25%, obtain the peak area of ​​each monomer in the total ion flow spectrum of the first sample, and calculate the photocuring rate R of the cured OCA to be tested; Where R= The OCA to be tested contains n monomers, A i C represents the peak area of ​​the monomer. i The response factor of the monomer. The peak area of ​​2,6-di-tert-butyl-p-cresol in the m / z 77 ion chromatogram of the first sample is denoted as S, where S is the mass percentage of 2,6-di-tert-butyl-p-cresol in the OCA to be tested. If Tr satisfies: 25% ≤ Tr < 40%, then the photocuring rate R of the cured OCA to be tested is calculated according to the following formula: Tr = 59.376 x R 3 - 186.73 x R 2 + 195.5 x R - 67.754 If Tr satisfies: 40%≤Tr<45%, then the photocuring rate of the cured OCA to be tested is 100%. The OCA to be tested includes a photocurable monomer, photoinitiator 651, and 2,6-di-tert-butyl-p-cresol; the content of photoinitiator 651 is 0.5 wt% to 3 wt%. In the Py-GC / MS test, the thermal decomposition temperature was 280~300℃.

2. The rapid characterization method for OCA photocurability according to claim 1, characterized in that, Also includes: At least two first samples were further photocured for 2t and 3t respectively to obtain third and fourth samples; The third and fourth samples were subjected to Py-GC / MS tests to obtain total ion chromatograms and m / z 77 ion chromatograms. The m / z 77 ion chromatograms of the third and fourth samples were normalized using the peak area of ​​2,6-di-tert-butyl-p-cresol in the m / z 77 ion chromatogram of the first sample. Then, the peak areas of methyl benzoate, azobenzoyl, and photoinitiator 651 in the normalized m / z 77 ion chromatograms of the third and fourth samples were obtained respectively, and the byproduct conversion rates Tr' and Tr'' were calculated. Where Tr'= ,Tr''= , , , The peak areas of photoinitiator 651, methyl benzoate, and azobenzoic acid are respectively in the m / z 77 ion chromatogram of the third sample after normalization. , , The peak areas of photoinitiator 651, methyl benzoate, and azobenzoic acid are respectively in the m / z 77 ion chromatogram of the fourth sample after normalization. When Tr' and Tr'' satisfy: 40%≤Tr'<45%, 40%≤Tr''<45%, and Tr'=Tr'', then the curing time t'~t'+t of the OCA to be tested is taken as the light curing endpoint; t' represents the curing time of the first sample.

3. The rapid characterization method for OCA photocurability according to claim 1, characterized in that, The content of 2,6-di-tert-butyl-p-cresol in the OCA to be tested is 0.1 wt% to 0.5 wt%.

4. The rapid characterization method for OCA photocurability according to claim 1, characterized in that, The photocurable monomer includes at least one of butyl acrylate, isooctyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, isobornyl acrylate, and dimethacrylamide.

5. The rapid characterization method for OCA photocurability according to claim 4, characterized in that, The response factor of butyl acrylate is 2.9, the response factor of isooctyl acrylate is 2.9, the response factor of hydroxyethyl acrylate is 2.9, the response factor of hydroxypropyl acrylate is 1.8, the response factor of isobornyl acrylate is 1.9, and the response factor of dimethacrylamide is 3.

6. The rapid characterization method for OCA photocurability according to claim 1, characterized in that, In the photocuring process, the irradiation intensity is the same as that used for the cured OCA to be tested.

7. The rapid characterization method for OCA photocurability according to claim 6, characterized in that, The irradiation intensity is 12~14 mW / cm² 2 .

8. The rapid characterization method for OCA photocurability according to claim 1, characterized in that, In the Py-GC / MS test, the lysis time was 10~30s.

9. The rapid characterization method for OCA photocurability according to claim 1, characterized in that, In the Py-GC / MS test, the column type was HP-5MS; the split ratio was (100~200):1; the interface temperature was 280~300℃; and the inlet temperature was 280~300℃. The GC heating program is as follows: hold at 40℃ for 2 min, then increase the temperature to 300℃ at a rate of 20℃ / min, and then hold at 300℃ for 10 min.

10. The rapid characterization method for OCA photocurability according to claim 1, characterized in that, In the m / z 77 ion chromatogram, the retention times of 2,6-di-tert-butyl-p-cresol were 9.895 min ± 0.1 min, methyl benzoate was 6.881 min ± 0.1 min, azobenzoyl was 11.711 min ± 0.1 min, and photoinitiator 651 was 12.044 min ± 0.1 min.

Images