Method for measuring curing rate of optical fiber coating

Abstract

The invention discloses a method for measuring the curing rate of an optical fiber coating. The method comprises the following steps: S1, forming a thin film with a preset thickness from an optical fiber coating to be measured; s2, irradiating the thin film with at least five gradient energy values by adopting an ultraviolet light source, wherein the gradient energy values cover an energy interval from non-curing to complete curing; s3, preparing the cured film under each energy point into a mechanical test sample strip; s4, testing the static elastic modulus of the cured film under each energy point; s5, establishing a function relationship between the static elastic modulus and the ultraviolet radiation energy; and S6, in the function relation curve, defining the corresponding ultraviolet radiation energy when the static elastic modulus reaches the maximum elastic modulus preset percentage as the curing rate. The determination method directly quantifies the curing rate based on the function change rule of the static elastic modulus along with the ultraviolet energy, can be suitable for optical fiber coating systems with any colors and components, is simple in steps, can shorten the single detection period, and reduces the test cost.

Description

Technical Field

[0001] This invention relates to the field of optical fiber coating performance testing technology, and in particular to a method for measuring the curing rate of optical fiber coatings. Background Technology

[0002] In the application of optical fiber coatings, accurate measurement of ultraviolet (UV) curing rate is crucial for optimizing photoinitiator ratio and curing process, directly affecting coating quality (such as adhesion and weather resistance) and production efficiency.

[0003] Currently, the determination of the UV curing rate of optical fiber coatings mainly relies on Fourier transform infrared spectroscopy (FTIR), based on the group standard T / CEMIA 009-2018 for curing rate analysis using infrared spectroscopy. The core approach of this method is as follows: Monitoring chemical bond changes: by tracking characteristic absorption peaks (e.g., 810 cm⁻¹) -1 1410cm -1 1730cm -1 The decay of (etc.) was assessed to evaluate the changes in chemical bonds during the curing process; Calculate the degree of solidification: Based on the peak area integral of the characteristic absorption peak, calculate the double bond conversion rate (AU%). The specific calculation formula is: AU = S 1410 / S 1730 , is used to represent the ratio of absorption peak areas; Calculate the absolute degree of cure (RAU): The formula is RAU = (AU) 液体 -AU 样品 ) / AU 液体 , of which AU 液体 AU is the ratio of the peak areas of the two absorption peaks of the liquid. 样品 This represents the peak area integral ratio of the two absorption peaks of the sample. Calculate the relative degree of cure (R-RAU): The formula is R-RAU = RAU UV剂量 / RAU （1.00 J / cm²） RAU UV Dosage refers to the RAU value at different UV doses (Dose), RAU （1.00 J / cm²） This indicates 1.0 J / cm 2 RAU value under UV dose; Fitting the curing rate curve: Plot the curing rate curve with UV Dose on the x-axis and R-RAU on the y-axis. This curve determines the UV dose required to achieve a relative cure rate of 95%, which is the curing rate.

[0004] Although the FTIR method is widely used, it has the following technical drawbacks: 1) Spectral peak overlap interference: Acrylic ester C=C bond (810 cm⁻¹)-1 ) and epoxy groups (915cm) -1 The peak positions are close together, which can easily overlap in complex formulations, leading to integration errors; 2) Low operational efficiency: The testing steps are time-consuming. Due to technical limitations, sample preparation takes 20 minutes, spectrum acquisition takes 10 minutes (scanning times ≥32 times to improve signal-to-noise ratio), peak resolution takes 5 minutes, and professional software is required to deconvolve overlapping peaks, totaling 35 minutes, which makes the single test cycle long. 3) Not suitable for dark-colored coatings: such as carbon black / pigments, which strongly absorb infrared light, resulting in a low signal-to-noise ratio.

[0005] In summary, the inherent limitations of existing FTIR methods in terms of detection accuracy, efficiency, and applicability make it difficult to meet the urgent need for a rapid and low-cost testing method for coating curing rates in industrial production. Therefore, there is an urgent need for a highly efficient, universal, and low-cost curing rate determination method based on entirely new fundamental principles. Summary of the Invention

[0006] To address the aforementioned technical problems, the present invention aims to provide a method for determining the curing rate of optical fiber coatings. This method is based on the functional variation of static elastic modulus with ultraviolet energy, directly quantifying the curing rate. It is applicable to optical fiber coating systems of any color and composition. Furthermore, the testing method is simple, shortens the single testing cycle, reduces testing costs, and supports the high-frequency testing requirements of industrial scenarios.

[0007] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution: A method for determining the curing rate of optical fiber coating, characterized by comprising the following steps: S1, the coating on the optical fiber to be tested is formed into a thin film of a predetermined thickness; S2, the film is irradiated with an ultraviolet light source at at least 5 gradient energy values, the gradient energy values ​​covering the energy range from uncured to fully cured; S3, prepare mechanical test specimens from the cured films at each energy point; S4, test the static elastic modulus of the cured film at each energy point; S5, establish the functional relationship between the static elastic modulus F and the ultraviolet radiation energy E: F=f(E); S6. In the function relationship curve, the ultraviolet radiation energy corresponding to the static elastic modulus reaching the preset percentage of the maximum elastic modulus is defined as the curing rate, denoted as V.

[0008] Further, in step S1, the coating material for the optical fiber under test is applied to a rigid substrate to form a thin film; the rigid substrate is selected from any of the following materials: a) Glass plate, 1-3 mm thick; b) Metal sheet, 0.5-2 mm thick; c) Engineering plastic sheets with an elastic modulus ≥3 GPa and a thickness of 2-5 mm.

[0009] Furthermore, the film thickness in step S1 is 100-200 μm.

[0010] Furthermore, step S2 is achieved through an ultraviolet irradiation system, which includes... An ultraviolet light source equipped with an energy sensor to monitor radiation energy in real time; The feedback controller dynamically adjusts the output of the ultraviolet light source to match the set gradient energy value with the actual radiation energy. A thin film conveying mechanism is used to transport a substrate carrying a thin film through an area irradiated by an ultraviolet light source.

[0011] Furthermore, in step S2, the gradient energy value is 0-1.5 J / cm². 2 .

[0012] Furthermore, in step S3, a custom mold is used to cut the cured film at each energy point into a mechanical test strip that is compatible with the universal tensile testing machine.

[0013] Furthermore, the dimensions of the mechanical test strip are: (10-20)mm × (70-90)mm × (0.1-0.2)mm.

[0014] Furthermore, in step S4, at least three mechanical test splines are tested at each different energy point, and the static elastic modulus F is taken as the arithmetic mean.

[0015] Furthermore, the test process in step S4 needs to be carried out at room temperature, and the environmental conditions are as follows: Temperature: 23±2℃, relative humidity: 50±5% RH. Before testing, the mechanical test specimens must be equilibrated in the test environment for at least 12 hours.

[0016] Furthermore, the universal tensile testing machine meets the ASTM D638 standard, with a maximum load ≤5 kN, a tensile testing rate of 0.1-10 mm / min, a strain measurement accuracy of ±0.001 MPa, and is equipped with a micro-clamp to perform tensile tests on cured films.

[0017] Furthermore, this universal tensile testing machine is a single-column tabletop model.

[0018] Furthermore, in step S6, the preset percentage is 90%-99%.

[0019] Furthermore, the curing rate (V) is used to determine the process window: when the actual ultraviolet radiation energy is greater than (1.1-1.5)V, the process enters the over-curing zone.

[0020] The beneficial effects of this invention are as follows: This invention provides a direct, universal, and efficient method for determining curing rate, overcoming the inherent limitations of traditional FTIR (Fourier Transform Infrared Spectroscopy). This method establishes a functional relationship F=f(E) between ultraviolet radiation energy (E) and the static elastic modulus (F) of the cured film, defining the energy corresponding to the preset percentage of the modulus reaching its maximum value as the curing rate (V). This represents a fundamental shift from indirectly monitoring chemical bond changes to directly measuring the final macroscopic mechanical properties. This transformation brings several significant benefits: First, it completely eliminates the problems of poor measurement accuracy and limited applicability caused by FTIR methods due to factors such as overlapping spectral peaks and light absorption by dark coatings, making it suitable for fiber optic coating systems of any color and composition. Second, this method eliminates the complex steps of spectrum acquisition and analysis, greatly simplifies the operation process, significantly shortens the single detection cycle, and improves detection efficiency, better meeting the urgent needs of high-frequency and rapid feedback in industrial production. Finally, the obtained curing rate (V) is a physical quantity with clear engineering significance, directly characterizing the critical point at which the material obtains key mechanical properties, providing direct and reliable data support for optimizing curing process parameters and preventing energy waste and over-curing.

[0021] Furthermore, by collecting modulus data at at least five gradient energy points, this invention plots a complete "energy-modulus" response curve (F=f(E)), thereby accurately pinpointing the curing rate (V)—the minimum energy required for the modulus to reach its maximum performance critical point. This not only enables quantitative measurement of the curing rate, rather than qualitative judgment, but also precisely defines the process windows of the "under-cured zone," "rapid curing zone," and "over-cured zone," providing an irreplaceable data foundation for optimizing production cycle time, ensuring coating quality consistency, and minimizing energy consumption. Attached Figure Description

[0022] Figure 1 This is a flowchart of the testing process for the present invention.

[0023] Figure 2 The graph shows the relationship between the static elastic modulus and the UV Dose function obtained by the test method in Embodiment 1 of the present invention.

[0024] Figure 3 The graph shows the relationship between the static elastic modulus and the UV Dose function obtained by the test method in Embodiment 2 of the present invention.

[0025] Figure 4The graph shows the relationship between the static elastic modulus and the UV Dose function obtained by the test method in Embodiment 3 of the present invention.

[0026] Figure 5 The curing rate curve is obtained by the test method of Comparative Example 1.

[0027] Figure 6 The curing rate curve is obtained by the test method of Comparative Example 2.

[0028] Figure 7 The curing rate curve is obtained by the test method of Comparative Example 3.

[0029] Specific implementation methods The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0030] like Figure 1 As shown, the present invention provides a method for determining the curing rate of optical fiber coating, which includes the following steps: S1, the coating material for the optical fiber to be tested is applied onto a rigid substrate to form a thin film; the rigid substrate is selected from any of the following materials: a) Glass plate, 1-3 mm thick; b) Metal sheet, 0.5-2 mm thick; c) Engineering plastic sheets with an elastic modulus ≥3 GPa and a thickness of 2-5 mm; The film thickness formed in this step is 100-200 μm.

[0031] S2, the film is irradiated with an ultraviolet light source at at least five gradient energy values, the gradient energy values ​​covering the energy range from uncured to fully cured; preferably, the gradient energy values ​​range from 0-1.5 J / cm. 2 The gradient energy value is 0 J / cm². 2 At that time, the film was actually not exposed to ultraviolet light; Specifically, step S2 is implemented through an ultraviolet irradiation system, which includes... An ultraviolet light source equipped with an energy sensor to monitor radiation energy in real time; The feedback controller dynamically adjusts the output of the ultraviolet light source to match the set gradient energy value with the actual radiation energy. A thin film conveying mechanism is used to transport a substrate carrying a thin film through an area irradiated by an ultraviolet light source.

[0032] S3, using a custom mold to cut the cured film at each energy point into mechanical test strips; the mechanical test strips are preferably test strips adapted to a universal tensile testing machine; the dimensions (length × width × thickness) of the mechanical test strips are preferably: (10-20)mm × (70-90)mm × (0.1-0.2)mm; The universal tensile testing machine meets ASTM D638 standards, with a maximum load ≤5 kN, a tensile testing rate of 0.1-10 mm / min, and a strain measurement accuracy of ±0.001 MPa. It is equipped with miniature clamps to perform tensile tests on cured films. The preferred model for this universal tensile testing machine is a single-column benchtop type.

[0033] S4, test the static elastic modulus of the cured film at each energy point; In step S4, at least three mechanical test splines are tested at each different energy point, and the static elastic modulus F is taken as the arithmetic mean. Furthermore, the testing process in step S4 must be conducted at room temperature, with the following environmental conditions: Temperature: 23±2℃, relative humidity: 50±5% RH. Before testing, the mechanical test specimens need to be equilibrated in the test environment for at least 12 hours.

[0034] S5, establish the functional relationship between the static elastic modulus F and the ultraviolet radiation energy E: F=f(E); S6. In the functional relationship curve, the ultraviolet radiation energy corresponding to the static elastic modulus reaching the preset percentage of the maximum elastic modulus is defined as the curing rate, denoted as V. The preset percentage of the maximum elastic modulus is 90%-99%, preferably 95%.

[0035] The curing rate (V) obtained from the test is used to determine the process window: when the actual ultraviolet radiation energy is > (1.1-1.5)V, it enters the over-curing zone.

[0036] The present invention will be further described below through specific embodiments.

[0037] Example 1 The method for determining the UV curing rate of the optical fiber coating in Example 1 includes the following steps: (1) Commercially available fiber optic coating sample A (Hanssen Coatings KS1076) was selected. The fiber optic coating to be tested was coated onto a 2mm glass plate to form a thin film with a thickness of 120±10μm. The film was irradiated with a UV light source at gradient energy values ​​E1, E2, ..., E9, with gradient energy values ​​UV Dose E being 0, 0.05, 0.10, 0.20, 0.40, 0.60, 0.80, 1.00 and 1.20 J / cm, respectively. 2The coating film was cut into strips of 15mm×80mm×0.12mm using a custom mold, in groups of three; the static modulus of elasticity was tested using a universal tensile testing machine, and the average value was calculated to obtain the average static tensile modulus F. (2) Plot the function relationship between UV Dose E and static elastic modulus F using UV Dose E as the abscissa and static elastic modulus F as the ordinate, as shown in the figure. Figure 2 In the f(E) curve, the UVDose (ultraviolet radiation energy) at the point where the maximum static elastic modulus is 95% is selected as the curing rate, denoted as V1.

[0038] Example 2 The method for determining the UV curing rate of the optical fiber coating in Example 2 includes the following steps: (1) Commercially available fiber optic coating sample B (Hanssen Coatings KS2046) was selected. The fiber optic coating to be tested was coated onto a 2mm metal plate to form a thin film with a thickness of 130±10μm. The film was irradiated with a UV light source at gradient energy values ​​E1, E2, ..., E9, where the gradient energy values ​​UV Dose E were 0, 0.05, 0.10, 0.20, 0.40, 0.60, 0.80, 1.00 and 1.20 J / cm, respectively. 2 The coating film was cut into strips of 15mm×80mm×0.12mm using a custom mold, in groups of 6. The static modulus of elasticity was tested using a universal tensile testing machine, and the average value was calculated to obtain the average static tensile modulus F. (2) Plot the function relationship between UV Dose E and static elastic modulus F using UV Dose E as the abscissa and static elastic modulus F as the ordinate, as shown in the figure. Figure 3 In the f(E) curve, the UVDose (ultraviolet radiation energy) at the point where the maximum static elastic modulus is 95% is selected as the curing rate, denoted as V2.

[0039] Example 3 The method for determining the UV curing rate of the coating in Example 3 includes the following steps: (1) Commercially available fiber optic coating sample C (Feikai Coating KG190) was selected. The fiber optic coating to be tested was coated onto a 2mm engineering plastic plate to form a thin film with a thickness of 140±10μm. The film was irradiated with a UV light source at gradient energy values ​​E1, E2, ..., E9, where the gradient energy values ​​UV Dose E were 0, 0.05, 0.10, 0.20, 0.40, 0.60, 0.80, 1.00 and 1.20 J / cm, respectively. 2The coating film was cut into strips of 15mm×80mm×0.12mm using a custom mold, in groups of 6. The static modulus of elasticity was tested using a universal tensile testing machine, and the average value was calculated to obtain the average static tensile modulus F.

[0040] (2) Plot the function relationship between UV Dose E and static elastic modulus F using UV Dose E as the abscissa and static elastic modulus F as the ordinate, as shown in the figure. Figure 4 In the f(E) curve, the UVDose (ultraviolet radiation energy) at the point where the maximum static elastic modulus is 95% is selected as the curing rate, denoted as V3.

[0041] Comparative Example 1 Comparative Example 1 relates to a method for determining the curing rate of a coating using infrared spectroscopy. A commercially available fiber optic coating sample A (Hanssen Coatings KS1076) was selected. The coating was coated onto a 2mm glass plate to form a thin film with a thickness of 120±10μm. The film was irradiated with a UV light source at gradient energy values ​​E1, E2, ..., E9, where the UV Dose gradient energy values ​​were 0, 0.05, 0.10, 0.20, 0.40, 0.60, 0.80, 1.00, and 1.20 J / cm², respectively. 2 First, the liquid coating was tested using an infrared spectrometer at a depth of 1410 cm⁻¹. -1 Integrate the absorption peak and then use the standard absorption peak at 1730 cm⁻¹. -1 The absorption peak integral, the area integral ratio of the two absorption peaks S1410 / S1730, is used to locate AU. 液体 The cured film was then tested using an infrared spectrometer at a depth of 1410 cm⁻¹. -1 Integrate the absorption peak and then use the standard absorption peak at 1730 cm⁻¹. -1 The absorption peak integral, the area integral ratio of the two absorption peaks S1410 / S1730, is used to locate the AU. 样品 ; Absolute Curing Degree RAU = (AU) 液体 -AU 样品 ) / AU 液体 ×100%, Relative Curing Degree R-RAU=RAU （UV Dose） / RAU （1.00 J / cm²） ×100%; where RAU is... （UV Dose） RAU for different UV Dose, RAU （1.00 J / cm²） 1.00 J / cm 2 The RAU is then plotted. Plotting R-RAU on the ordinate and UV Dose on the abscissa yields a curing rate curve, as shown below. Figure 5 The UV Dose at a relative curing degree of 95% is obtained from the curve and is taken as the curing rate, denoted as V1´.

[0042] Comparative Example 2 Comparative Example 2 relates to a method for determining the curing rate of a coating using infrared spectroscopy. The test method is basically the same as that of Comparative Example 1, except that fiber optic coating sample A is replaced with fiber optic coating sample B (Hanssen Coatings KS2046). The fiber optic coating to be tested is coated onto a 2 mm metal plate, forming a thin film with a thickness of 130 ± 10 μm. The resulting curve is the curing rate curve, as shown below. Figure 6 The curing rate is denoted as V2'.

[0043] Comparative Example 3 Comparative Example 3 relates to a method for determining the curing rate of a coating using infrared spectroscopy. The test method is basically the same as that of Comparative Example 1, except that fiber optic coating sample A is replaced with fiber optic coating sample C (Feikai Coating KG190). The fiber optic coating to be tested is coated onto a 2mm engineering plastic plate, forming a thin film with a thickness of 140±10 μm. The obtained curve is the curing rate curve, as shown below. Figure 7 The curing rate is denoted as V3'.

[0044] The curing rate was tested using the static modulus of elasticity method (Examples 1-3) and the curing rate was tested using infrared spectroscopy (Comparative Examples 1-3). The test results are shown in Table 1.

[0045] Table 1 As shown in Table 1, the curing rates tested by the two methods in the examples and comparative examples are highly consistent. The examples reduce testing costs by using a universal tensile testing machine to test the static elastic modulus; the curing rate is directly obtained by plotting UV Does against the static elastic modulus F, which is a simple method; and it can be used to test different coatings, making it widely applicable and a viable alternative to infrared spectroscopy for determining the curing rate.

[0046] The above description is only a preferred embodiment of the present invention. It should be noted that the parameters such as UVDose gradient and stretching rate in the embodiments should not be construed as limiting the present invention. Any equivalent substitutions or adaptive modifications made by those skilled in the art without departing from the core principles of the present invention, such as using other static mechanical testing methods, adjusting function algorithms, and optimizing the structure of the online detection system, and any improvements and transformations based on the inventive concept of using static modulus to replace infrared spectroscopy to calculate curing rate, fall within the scope of protection of the claims of the present invention.

Claims

1. A method for determining the curing rate of optical fiber coating, characterized in that, Includes the following steps: S1, the coating on the optical fiber to be tested is formed into a thin film of a predetermined thickness; S2, the film is irradiated with an ultraviolet light source at at least 5 gradient energy values, the gradient energy values ​​covering the energy range from uncured to fully cured; S3, prepare mechanical test specimens from the cured films at each energy point; S4, test the static elastic modulus of the cured film at each energy point; S5, establish the functional relationship between the static elastic modulus F and the ultraviolet radiation energy E: F=f(E); S6. In the function relationship curve, the ultraviolet radiation energy corresponding to the static elastic modulus reaching the preset percentage of the maximum elastic modulus is defined as the curing rate, denoted as V.

2. The method for determining the curing rate of optical fiber coating according to claim 1, characterized in that, In step S1, the coating material for the optical fiber under test is applied to a rigid substrate to form a thin film; the rigid substrate is selected from any of the following materials: a) Glass plate, 1-3 mm thick; b) Metal sheet, 0.5-2 mm thick; c) Engineering plastic sheets with an elastic modulus ≥3 GPa and a thickness of 2-5 mm.

3. The method for determining the curing rate of optical fiber coating according to claim 1, characterized in that, The film thickness in step S1 is 100-200 μm.

4. The method for determining the curing rate of optical fiber coating according to claim 1, characterized in that, Step S2 is achieved through an ultraviolet irradiation system, which includes... An ultraviolet light source equipped with an energy sensor to monitor radiation energy in real time; The feedback controller dynamically adjusts the output of the ultraviolet light source to match the set gradient energy value with the actual radiation energy. A thin film conveying mechanism is used to transport a substrate carrying a thin film through an area irradiated by an ultraviolet light source.

5. The method for determining the curing rate of optical fiber coating according to claim 1, characterized in that, In step S2, the gradient energy value is 0-1.5 J / cm. 2 .

6. The method for determining the curing rate of optical fiber coating according to claim 1, characterized in that, In step S3, a custom mold is used to cut the cured film at each energy point into mechanical test strips that are compatible with the universal tensile testing machine.

7. The method for determining the curing rate of optical fiber coating according to claim 1, characterized in that, The dimensions of the mechanical test strip are: (10-20)mm × (70-90)mm × (0.1-0.2)mm.

8. The method for determining the curing rate of optical fiber coating according to claim 1, characterized in that, In step S4, at least three mechanical test splines are tested at each different energy point, and the static elastic modulus F is taken as the arithmetic mean.

9. The method for determining the curing rate of optical fiber coating according to claim 1, characterized in that, In step S6, the preset percentage is 90%-99%.

10. The method for determining the curing rate of optical fiber coating according to claim 1, characterized in that, The curing rate is used to determine the process window: when the actual ultraviolet radiation energy is greater than (1.1-1.5)V, it enters the over-curing zone.

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