Performance research method for color stability of polymer material additive under exposure of natural light

Abstract

The invention relates to the field of material performance research, in particular to a performance research method for color stability of a high polymer material additive under natural light exposure. The performance research method comprises the following steps: A) uniformly mixing an additive and a solvent in a transparent glass bottle to obtain a solution; sampling and detecting the light transmittance and the yellow index under a specific wavelength, and covering the transparent glass bottle with a sealing cover; b) exposing the transparent glass bottle with natural light, and regularly sampling to detect the light transmittance and the yellow index under a specific wavelength; and C) counting the light transmittance data and the yellow index data, comparing, and measuring the color stability of the additive under the exposure of natural light. According to the method, solution preparation, natural exposure, regular observation, light transmittance and yellow index detection are combined, data in a specific period are effectively accumulated, the color stability and the change rule of different additives under the natural light exposure condition are obtained, and the color change degree of the additives exposed in the natural light for each time period can be calculated according to the accumulated data.

Description

Technical Field

[0001] The invention relates to the field of material performance research, and in particular to a performance research method for color stability of a polymer material additive under natural light exposure. Background Art

[0002] The color and color stability of materials are one of the key concerns of the market. The color of materials is usually characterized by the yellow index, which indicates the degree of deviation from white or yellowing of polymer materials. The yellower the color, the larger the yellow index; the whiter the color, the smaller the yellow index, and the yellow index is usually required to be less than 3. The detection method is to use a magnesium oxide standard white board as a benchmark under a standard light source, and calculate the reflectivity (or transmittance) of the sample to red, green and blue light to obtain a measure of the depth of yellow. Measure with a colorimeter or colorimeter, or spectrophotometer under standard C light source. Sometimes polymer material processors also have a yellow index to judge the quality or aging of polymer material products.

[0003] In fact, the color and yellowness index of polymer materials are related to factors such as the quality of additives and material bases, processing equipment, and processing parameters such as temperature and shear strength. In particular, they are related to the types of additives, including antioxidants, light stabilizers, and ultraviolet absorbers, as well as the substances that may be generated during the use of these additives. They are also related to the amount of additives added and the characteristics of the formula.

[0004] Antioxidants are widely used in the fields of food, daily chemicals and medicine. Antioxidants can inhibit oxidation reactions in products and reduce product deterioration. Their main function is to extend the shelf life of products or maintain stable product quality. In order to improve the color stability of polymer materials such as plastics and rubber, antioxidants or light stabilizers are usually added to the materials. After antioxidants / light stabilizers are added to polymer materials, they can inhibit oxidation reactions by capturing free radicals and peroxides, thereby delaying the yellowing and aging of polymer products and extending the service life of products. For example, hindered phenol antioxidants are a type of antioxidant with excellent high-temperature stability. After being added to polymer materials such as plastics and rubber, they inhibit the oxidation reaction of products by capturing free radicals, thereby extending the service life of products. Phosphite antioxidants are also a type of antioxidant with good high-temperature stability. After being added to polymer materials such as plastics and rubber, they prevent oxidation chain reactions by capturing peroxides, thereby improving the heat resistance of products, effectively preventing yellowing of products at high temperatures, and maintaining the appearance of products. Thioester antioxidants are also a type of antioxidant that performs well at high temperatures. When added to polymer materials such as plastics and rubber, they decompose to produce free radical scavengers to inhibit the oxidation reaction of the product, thereby improving the heat resistance of the product and preventing the product from yellowing and aging at high temperatures.

[0005] The above are all the effects of antioxidants added to polymer products such as plastics and rubber on the stability of polymer products. There are many such studies in the prior art. For example, the aging resistance and heat resistance of products are improved after adding antioxidants to various material systems, and the effects of different antioxidants on the aging resistance of different material systems. However, most of the prior art focuses on the aging resistance, color stability, heat resistance, etc. of polymer products, and rarely pays attention to the color stability of the antioxidant itself.

[0006] There are many kinds of antioxidants on the market. Some antioxidants have poor stability and may change color during production and application. The reasons for the discoloration may be: long-term light exposure, high temperature, contact with oxygen, etc. Antioxidant discoloration not only affects the appearance quality of the product, but may also have a negative impact on the performance and service life of the product, reducing consumers' willingness to buy. However, some antioxidants are very stable, at least on the surface. For example, antioxidant 1010, antioxidant 168, etc., all have the appearance of white crystalline powder, and their chemical properties are very stable. The color remains basically unchanged after being stored for months or even years. Due to their stable properties, there are generally no special requirements for their storage, as long as they are conventionally moisture-proof and heat-insulated. Its color is usually expressed by visual inspection. For example, after a period of storage and use, if the raw material bottle is opened and visually observed to be still a white crystalline powder, it is considered that its color is stable.

[0007] The color and yellow index of polymer products are related to the factors mentioned above, as well as the color and color stability of additives such as antioxidants, light stabilizers, and other substances produced during the application process. However, at present, the color and color stability of the additives themselves are usually determined by visual inspection. If there is no change in the visual color, the antioxidant color is assumed to be stable. On the one hand, this visual inspection method cannot accurately express the degree and change of color digitally. On the other hand, it cannot express the effect of the additive added to the material on the discoloration of the antioxidant component during the long-term exposure to light during the use of the material product, which will cause misjudgment of the color stability of the additive, and then lead to inadequate analysis of the factors of the long-term color stability of polymer materials, which is not conducive to the study of the color stability of polymer materials. Factors affecting the color stability of materials are also the focus of polymer material production and product manufacturers, but some research conclusions are only theoretical, such as the chromophores produced during the aging process, the color pollution of amine antioxidants, and the quinone substances generated during the anti-aging process of phenolic antioxidants. However, there is no effective method to study the color stability and change rules of different additives in polymer materials including antioxidants. Summary of the invention

[0008] In view of this, the present invention provides a method for studying the color stability of polymer material additives under natural light exposure. The method of the present invention can simply and sensitively measure the color change of the additive.

[0009] The present invention provides a method for studying the color stability of a polymer material additive under exposure to natural light, comprising the following steps:

[0010] A) mixing the additive and the solvent in a transparent glass bottle to obtain a solution; sampling to detect the transmittance at a specific wavelength and the yellowness index, and covering the transparent glass bottle with a sealing cover;

[0011] B) exposing the transparent glass bottle to natural light, and regularly sampling to detect light transmittance and yellowness index at a specific wavelength;

[0012] C) Collect transmittance data and yellow index data, compare them, and measure the color stability of the additive under exposure to natural light.

[0013] Preferably, the additive is one of an antioxidant, a light stabilizer, a UV absorber, 2,4-di-tert-butylphenol, and 3,5-methyl ester.

[0014] Preferably, the additive is one of antioxidant 1010, antioxidant 168, antioxidant 57, UV-329, hindered amine light stabilizer 770, 2,4-di-tert-butylphenol, and 3,5-methyl ester.

[0015] Preferably, the solvent is toluene.

[0016] Preferably, the mass ratio of the additive to the solvent is 8:(16-8000).

[0017] Preferably, the specific wavelength is 500 nm and / or 425 nm.

[0018] Preferably, the light transmittance detection method comprises: pouring the sample into a cuvette, placing it in a spectrophotometer, using a blank solvent as a reference, and measuring the light transmittance at a specific wavelength;

[0019] The yellow index detection method comprises: installing a transmission target mask on the illumination window of the transmission sample chamber of a CM-5 spectrophotometer, then installing a colorimetric cell containing a sample to be tested on the instrument using a transmission measurement kit, selecting a transmission measurement mode, and testing the yellow index of the sample.

[0020] Preferably, in step A) and step B), before each sampling and testing, the color of the solution sample is observed and recorded.

[0021] Preferably, in step B), the periodic sampling and testing is performed once every certain period of time, and the time intervals between each time can be the same or different.

[0022] Preferably, in step B), the periodic sampling and testing are respectively performed on the 3rd day, the 7th day, the 15th day, the 30th day, the 60th day and one year.

[0023] The performance research method of the present invention combines solution preparation, natural exposure, regular observation, transmittance, and yellow index detection to effectively accumulate data under a specific period, and obtain the color stability (i.e., color change) and change rules of different additives under natural light exposure conditions. The degree of color change of the additive after exposure to natural light for various time periods can also be calculated based on the accumulated data. Compared with the visual inspection method, the color change and degree of the additive can be effectively and accurately measured, which is of great significance to color property research and formula design. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0025] Figure 1 This is a bar chart showing the trend of the transmittance at 425 nm after exposure aging of the samples in Example 1-2;

[0026] Figure 2 This is a bar chart showing the trend of the 500nm transmittance variation of the samples in Example 1-2 after exposure aging;

[0027] Figure 3 This is a bar chart showing the trend of the yellow index changes after exposure aging of the samples in Example 1-2;

[0028] Figure 4 The visual effect diagram of the sample of Example 1 on the first day and one year after exposure aging; wherein the sample on the left is the sample on the first day, and the sample on the right is the sample after one year of exposure aging;

[0029] Figure 5 The visual effect diagram of the solid sample of antioxidant 1010 on the first day and one year after exposure aging; the sample on the left is the sample on the first day, and the sample on the right is the sample after one year of exposure aging;

[0030] Figure 6 This is the liquid chromatogram of the sample in Example 1 after exposure and aging for one year;

[0031] Figure 7 The visual effect diagram of the samples of Example 2 on the first day and one year after exposure aging; wherein the sample on the left is the sample on the first day, and the sample on the right is the sample after one year of exposure aging;

[0032] Figure 8The visual effect diagram of the solid sample of antioxidant 168 on the first day and one year after exposure aging; the sample on the left is the sample on the first day, and the sample on the right is the sample after one year of exposure aging;

[0033] Fig. 9 This is the liquid chromatogram of the sample in Example 2 after exposure and aging for one year. DETAILED DESCRIPTION

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0035] The present invention provides a method for studying the color stability of a polymer material additive under exposure to natural light, comprising the following steps:

[0036] A) mixing the additive and the solvent in a transparent glass bottle to obtain a solution; sampling to detect the transmittance at a specific wavelength and the yellowness index, and covering the transparent glass bottle with a sealing cover;

[0037] B) exposing the transparent glass bottle to natural light, and regularly sampling to detect light transmittance and yellowness index at a specific wavelength;

[0038] C) Collect transmittance data and yellow index data, compare them, and measure the color stability of the additive under exposure to natural light.

[0039] [About Step A]:

[0040] A) mixing the additive and the solvent in a transparent glass bottle to obtain a solution; taking a sample to detect the transmittance at a specific wavelength and the yellowness index, and covering the transparent glass bottle with a sealing cover.

[0041] In the present invention, the additive is an additive in a polymer material, preferably one of an antioxidant, a light stabilizer, an ultraviolet absorber, 2,4-di-tert-butylphenol, and 3,5-methyl ester. Among them, 2,4-di-tert-butylphenol or 3,5-methyl ester is a raw material for preparing an antioxidant.

[0042] The antioxidant may be one of a hindered phenol antioxidant, a diphenylamine antioxidant, a phosphite antioxidant, a sulfur-containing antioxidant, a hydroxylamine antioxidant, and a benzofuranone antioxidant; wherein the hindered phenol antioxidant is preferably antioxidant 1010, antioxidant 1076, antioxidant 1330, antioxidant 3114, antioxidant 1135, antioxidant 1285, antioxidant 1315, antioxidant BHT, antioxidant 1024, antioxidant 1098, antioxidant 1790, antioxidant 245, antioxidant AO-80, antioxidant 565, antioxidant 1425, antioxidant 1035, or antioxidant 300. The diphenylamine antioxidant is preferably antioxidant 57 or antioxidant 405. The phosphite antioxidant is preferably antioxidant 168 or antioxidant 626. The sulfur-containing antioxidant is preferably antioxidant DSTDP, antioxidant 1520 or antioxidant 412S. The hydroxylamine antioxidant is antioxidant 186. The benzofuranone antioxidant is preferably antioxidant 136. The ultraviolet absorber is preferably UV-327 or UV-329. The light stabilizer is preferably a hindered amine light stabilizer, more preferably light stabilizer 622, light stabilizer 770, light stabilizer 292, light stabilizer 944. In addition to the above types, the additive can also be a nucleating agent, preferably 3988, 8000K or 8000I.

[0043] In the present invention, more preferably, the additive is one of antioxidant 1010, antioxidant 168, antioxidant 57, UV-329, hindered amine light stabilizer 770, 2,4-di-tert-butylphenol, and 3,5-methyl ester.

[0044] In the present invention, the solvent is preferably toluene. The present invention uses toluene as a solvent, which can fully dissolve the antioxidant and is stable, which is conducive to ensuring the accuracy of the test results. If other solvents are used, it will be detrimental to the test results.

[0045] In the present invention, the mass ratio of the additive to the solvent is preferably 8:(16-8000), more preferably 8:(16-800), further preferably 8:(16-500), further preferably 8:(50-100), and most preferably 8:80.

[0046] In the present invention, after the additive and the solvent are added into the transparent glass bottle, the mixing method can be stirring, shaking or ultrasonic dissolution, preferably ultrasonic treatment, so that the additive and the solvent are fully and evenly dissolved by ultrasonic treatment to obtain a solution.

[0047] In the present invention, after the solution is obtained, a sample is taken to detect the light transmittance and yellowness index at a specific wavelength.

[0048] in:

[0049] The sampling volume of the sampling is preferably 3.5 mL.

[0050] The transmittance at a specific wavelength is detected, wherein the specific wavelength is 500nm and / or 425nm, that is, the transmittance at 500nm is detected, or the transmittance at 425nm is detected, or the transmittance at both 500nm and 425nm is detected, and the transmittance at 425nm is more preferably detected. At the above specific wavelength, the transmittance change of the sample can be sensitively detected, and then its color stability / color change can be determined.

[0051] The transmittance detection method is preferably as follows: pour the sample into a cuvette, place it in a spectrophotometer, use a blank solvent as a reference, and measure the transmittance at a specific wavelength. The cuvette is preferably a quartz cuvette, more preferably a quartz cuvette with a diameter of 10 mm. The solvent used for the reference is the same as the solvent in the sample to be tested, preferably toluene.

[0052] The yellow index (YI) detection method is preferably as follows: install the transmission target mask on the illumination window of the transmission sample chamber of the CM-5 spectrophotometer, then install the cuvette containing the sample to be tested on the instrument using the transmission measurement kit, select the transmission measurement mode, and test the yellow index of the sample. The cuvette is preferably a quartz cuvette, more preferably a quartz cuvette with a diameter of 10 mm.

[0053] In the present invention, after sampling, the transparent glass bottle is covered with a sealing cap. There is no special restriction on the order of detecting the transmittance and yellow index at a specific wavelength and sealing the transparent glass bottle cap after sampling. After sampling, the glass bottle can be immediately covered with a sealing cap, and then the sample is tested, or the sample is tested first, and then the glass bottle is covered with a sealing cap.

[0054] The light transmittance and yellowness index data measured in step A) are the initial data, namely the initial light transmittance and initial yellowness index.

[0055] [About step B]:

[0056] B) exposing the transparent glass bottle to natural light, and regularly sampling to detect light transmittance and yellowness index at a specific wavelength.

[0057] In the present invention, the transparent glass bottle is fixed at the same position when exposed to natural light, that is, the sample exposed to natural light at the same position is monitored for a long time. The transparent glass bottle is preferably placed on a windowsill or window edge so that it can be exposed to natural light and is easy to observe at any time.

[0058] In the present invention, under exposure to natural light, samples are taken regularly to detect the transmittance at the wavelength and the yellow index. Wherein, the regular refers to sampling and testing at intervals, and the time intervals between each time can be the same or different. In some embodiments of the present invention, samples are taken and tested on the 3rd day, the 7th day, the 15th day, the 30th day, the 60th day, and the 1st year.

[0059] In the present invention, the detection of light transmittance at a specific wavelength and the detection of the yellow index are the same as the detection method in step A), and will not be described in detail here.

[0060] [About Step C]:

[0061] C) Collect transmittance data and yellow index data, compare them, and measure the color stability of the additive under exposure to natural light.

[0062] In the present invention, counting the transmittance data and the yellow index data and comparing them means counting all the transmittance data and the yellow index data of steps A) to B), and comparing each data item, examining the changes in the transmittance data and the yellow index data of the sample as the exposure time to natural light increases, thereby determining the color stability and color change of the additive under exposure to natural light, and also studying the color change law under exposure to natural light.

[0063] In the present invention, after the transmittance data and the yellowness index data are statistically analyzed, the degree of color change of the additive after being exposed to natural light for a certain period of time can also be calculated, which can be specifically reflected by the change in transmittance and / or the change in yellowness index. The calculation method is shown in formula (1) and formula (2):

[0064] Transmittance change = transmittance at a certain period - initial transmittance (1);

[0065] Yellowness index change ΔYI = yellowness index at a certain period - initial yellowness index (2);

[0066] Through the above calculation method, the degree of color change of the additive after exposure to natural light for different time periods can be obtained.

[0067] During the testing process of the present invention, before each sampling test, it is preferred to visually observe the color of the sample and record it so as to compare the visual observation effect with the test effect.

[0068] The performance research method of the present invention combines solution preparation, natural light exposure, regular observation, transmittance, and yellowness index detection to effectively accumulate data under a specific period, and obtain the color stability and change rules of different additives under natural light exposure conditions. The color change degree of the additive after exposure to natural light for various time periods can also be calculated based on the accumulated data. Compared with a single visual inspection method, the color change and the degree of change of the additive can be effectively and accurately measured, which is of great significance to color property research and formula design.

[0069] The invention has the following beneficial effects: the method of the invention is based on the characteristics of polymer material additives and is combined with the use status of the additives in the polymer material, especially after the antioxidant is added to the polymer material, it mainly works by moving to the near-surface layer of the polymer sub-material, and the region is close to the polymer material solution of the additive. During use, the additive is easily affected by light, and the additive is prepared into a toluene solution of a certain concentration to achieve uniform illumination of the sample; the method of the invention adopts a method combining a transparent solution and a transparent container, which is conducive to sufficient illumination, convenient for visual observation, and sensitive to color changes; the experimental process of the method of the invention is intuitive and simple, the phenomenon is obvious, and the data is accurate.

[0070] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0071] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods. Experimental instruments: 20-100 ml cylindrical glass bottle with metal cover (height 4-12 cm), diameter 37 cm; spectrophotometer, Yidian Jingke 721G-100 visible spectrophotometer; Japan KonicMinolta CM-5 spectrophotometer CM-5, CM-A98 quartz cuvette.

[0072] Example 1

[0073] 1. Test of Antioxidant 1010

[0074] A) Weigh 8g (accurate to 0.001g) of antioxidant 1010 and add it to a 100mL glass bottle. Then add 80g of toluene to the glass bottle and dissolve it completely by ultrasonic to obtain a solution. Observe the color of the solution, take a sample of 3.5mL, and test the transmittance at 425nm, the transmittance at 500nm, and the yellowness index YI, which are the initial data. Cover the transparent glass bottle with a sealing cap.

[0075] The transmittance test was performed as follows: 3.5 mL of the solution was poured into a quartz cuvette with a diameter of 10 mm, placed in a spectrophotometer, and toluene was used as a reference to measure the transmittance at wavelengths of 425 nm and 500 nm, respectively.

[0076] The yellow index test is as follows: install the transmission target mask on the illumination window of the transmission sample chamber of the CM-5 spectrophotometer, then install the 10mm diameter quartz colorimetric cell containing the solution to be tested on the instrument using the transmission measurement kit, select the transmission measurement mode, and test the yellow index of the sample.

[0077] B) Place the transparent glass bottle on the laboratory windowsill to expose it to natural light, observe and record the color changes regularly, and take samples regularly to test the transmittance and yellowness index at a specific wavelength. Specifically, the regular testing is: testing and recording on the 3rd day, 7th day, 15th day, 30th day, 60th day, and 1 year.

[0078] The performance research method of light transmittance and yellowness index is the same as step A).

[0079] C) Count all the transmittance data and yellow index data obtained in steps A) to B) and compare them to measure the color stability of the additive under natural light exposure. The results are shown in Tables 1 and Figures 1 to 3 ;in, Figure 1 This is a bar chart showing the trend of the 425nm transmittance of the samples in Example 1-2 after exposure and aging. Figure 2 This is a bar chart showing the trend of the 500nm transmittance variation of the samples in Example 1-2 after exposure aging. Figure 3 This is a bar chart showing the trend of the yellow index changes after exposure aging of the samples in Example 1-2.

[0080] In addition, the color of the sample solution in Example 1 was recorded. Figure 4 As shown, Figure 4 The visual effect diagram of the sample of Example 1 after exposure aging. In addition, the solid sample of antioxidant 1010 was visually inspected after exposure aging. The results are as follows Figure 5 As shown, Figure 5 This is a visual observation of the exposure aging effect of the solid sample of antioxidant 1010.

[0081] Table 1: Color change test results of antioxidant 1010

[0082]

[0083] Note: In visual inspection, no change means that the solution color / solid-like properties are unchanged compared to the initial sample, and the change cannot be discerned by the naked eye.

[0084] From the visual inspection method in Table 1, the solid sample of the antioxidant itself has no obvious change with the extension of exposure time under natural light, and the change in the appearance of the antioxidant 1010 can hardly be observed by the naked eye. According to the conventional mindset in this field, it is believed that its color stability is good and the color does not change. From the visual inspection (solution) item in Table 1, it can be clearly observed that the initial color and the color after 1 year of exposure have changed significantly, but the changes in the process are relatively similar; and from the other test items and the graphical test results in Table 1, it can be seen that with the extension of exposure time under natural light, the transmittance and yellow index of the antioxidant 1010 have changed significantly, and accurate data have been achieved, indicating that the antioxidant 1010 will change color when exposed to natural light in a dispersed state of solution molecules. It proves that the visual inspection method cannot measure the color change of the solid antioxidant 1010, and the performance research method of the present invention can effectively and sensitively measure its color change.

[0085] In addition, the samples after one year of exposure and aging were tested by liquid chromatography. The results are as follows: Figure 6 As shown, it can be seen that after one year of exposure to toluene solution, the 1010 component has undergone significant changes, generating more 3,5-methyl ester and other impurities, and the 1010 content has decreased significantly.

[0086] 2. Calculation of color change degree:

[0087] According to the test results in Table 1, the degree of color change after each exposure aging period is calculated respectively. The results are shown in Table 2.

[0088] Table 2: Color change of antioxidant 1010 after exposure and aging for different time periods

[0089]

[0090] It can be seen from the test results in Table 2 that within 60 days of exposure aging, the change in transmittance at a wavelength of 425nm is more obvious than that at 500nm. Therefore, at the preferred wavelength of 425nm, the transmittance test effect is more sensitive.

[0091] 3. Blank experiment:

[0092] The performance study method in Section 1 was followed, except that no antioxidant 1010 was added and a blank test of toluene solvent was performed. The results are shown in Table 3.

[0093] Table 3: Test results of toluene solvent

[0094]

[0095] From the test results in Table 3, it can be seen that with the extension of exposure time, the transmittance and yellowness index of toluene basically do not change, and the color stability of toluene itself is good, and basically does not change within 1 year. This proves that the changes in transmittance and yellowness index in the test results of Section 1 come from antioxidant 1010.

[0096] Example 2

[0097] 1. Test of Antioxidant 168

[0098] The method was implemented according to Example 1, except that the antioxidant 1010 was replaced by the antioxidant 168. The test results are shown in Tables 4 and Figures 1 to 3 ,7~8; among them, Figure 7 This is a visual effect diagram of the exposure aging of the sample in Example 2. Figure 8 This is a visual observation of the exposure aging effect of the solid sample of antioxidant 168.

[0099] Table 4: Color change test results of antioxidant 168

[0100]

[0101] From the visual inspection method in Table 4, with the extension of exposure time under natural light, there is no obvious change in the solid antioxidant 168, and the change in appearance is almost impossible to observe with the naked eye. The color of the 168 solution is very stable in the first 15 days, but the color turns yellow significantly on the 60th day, and turns orange-red after one year of exposure. As can be seen from the other test items and the graphical test results in Table 2, with the extension of exposure time under natural light, the transmittance and yellowness index of the antioxidant 168 change significantly, indicating that the antioxidant 168 will change color when exposed to natural light. It proves that the visual inspection method cannot detect the color change of the solid antioxidant 168, and the performance research method of the present invention can effectively and sensitively measure its color change law in a molecularly dispersed state.

[0102] In addition, the samples after one year of exposure and aging were tested by liquid chromatography. The results are as follows: Fig. 9 As shown, it can be seen that after one year of exposure to toluene solution, component 168 has undergone significant changes, generating some 2,4-di-tert-butylphenol and a large number of unknown impurities, and component 168 can no longer be detected.

[0103] 2. Calculation of color change degree:

[0104] According to the test results in Table 4, the degree of color change after each exposure aging period is calculated respectively. The results are shown in Table 5.

[0105] Table 5: Color change of antioxidant 168 after exposure and aging for different time periods

[0106]

[0107] It can be seen from the test results in Table 5 that the light transmittance change at a wavelength of 425 nm is more obvious than that at 500 nm. Therefore, at the preferred wavelength of 425 nm, the light transmittance test effect is more sensitive.

[0108] Example 3

[0109] Color stability tests and data of other additives, such as 2,4-di-tert-butylphenol, 3,5-methyl ester, antioxidant 57, UV-329, hindered amine light stabilizer 770, etc.

[0110] The method was implemented according to Example 1, except that the antioxidant 1010 was replaced by 2,4-di-tert-butylphenol, 3,5-methyl ester, antioxidant 57, UV-329, and hindered amine light stabilizer 770. The test results of the 425nm transmittance, 500nm transmittance, and YI index are shown in Tables 6, 7, and 8.

[0111] Table 6: Test data of light transmittance of each additive at 425nm wavelength versus exposure time

[0112] 425nm transmittance initial Day 3 Day 7 Day 15 Day 30 Day 60 1 year 2,4-Di-tert-butylphenol 99.1 98.8 98.7 98.6 98.5 96.4 28.1 3,5-Methyl ester 99.8 93.3 88.9 73.7 54.2 34.5 0.33 Antioxidant 57 80.3 49.5 36.1 18.7 5.5 2.5 0.17 UV-329 92.6 92.4 92.2 91.5 89.9 88.4 86.4 Hindered Amine Light Stabilizer 770 99.7 99.3 99 99.1 98.9 98 94.1

[0113] Table 7: Test data of light transmittance of each additive at 425nm wavelength versus exposure time

[0114] 500nm transmittance initial Day 3 Day 7 Day 15 Day 30 Day 60 1 year 2,4-Di-tert-butylphenol 99.3 100.1 100.2 99.5 99.6 99 52.9 3,5-Methyl ester 100.1 96.6 98.4 95.3 90.9 87.6 9.87 Antioxidant 57 85.8 58.5 47.6 29.8 11.4 3.1 0.01 UV-329 99.1 98.9 98.8 98.9 96.7 96.6 96.1 Hindered Amine Light Stabilizer 770 99.7 99.7 99 99.5 99.5 98.3 96.1

[0115] Table 8: Yellowness index (YI) test data of each additive with exposure time

[0116] YI initial Day 3 Day 7 Day 15 Day 30 Day 60 1 year 2,4-Di-tert-butylphenol -1.13 -1.02 0.28 0.29 0.26 1.15 59.88 3,5-Methyl ester -2.16 2.33 4.73 22.39 23.57 35.93 187.97 Antioxidant 57 8.97 41.87 73.76 89.22 226.73 409 889.1 UV-329 3.87 3.99 4.13 4.01 4.2 4.66 5.87 Hindered Amine Light Stabilizer 770 -2.96 -1.86 -1.52 -1.5 -1.47 0.68 2.91

[0117] Comparative Example 1

[0118] The method was implemented according to Example 1, except that the transmittance was measured at a wavelength of 360 nm. The test results were compared with those of Example 1, and the results are shown in Table 9.

[0119] Table 9: Color change test results of antioxidant 1010

[0120]

[0121] It can be seen from the test results in Table 9 that the transmittance at a wavelength of 360 nm is generally lower than that at 425 nm and 500 nm, which is not conducive to accurately reflecting its color stability; compared with 425 nm, it has a low degree of integration with the color change; compared with 500 nm, it has a low degree of integration with the visual solution transparency.

[0122] Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enable any technician in the field to practice the present invention, including making and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements similar to the literal expression of the claims, or if they include equivalent structural elements that are not substantially different from the literal expression of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A method for studying the color stability of polymer material additives under natural light exposure, characterized in that: The following steps are involved: A) mixing the additive and the solvent in a transparent glass bottle to obtain a solution; sampling to detect the transmittance at a specific wavelength and the yellowness index, and covering the transparent glass bottle with a sealing cover; B) exposing the transparent glass bottle to natural light, and regularly sampling to detect light transmittance and yellowness index at a specific wavelength; C) Collect transmittance data and yellow index data, compare them, and measure the color stability of the additive under natural light exposure.

2. The performance research method according to claim 1, characterized in that: The additive is one of an antioxidant, a light stabilizer, an ultraviolet absorber, 2,4-di-tert-butylphenol, and 3,5-methyl ester.

3. The performance research method according to claim 1 or 2, characterized in that: The additive is one of antioxidant 1010, antioxidant 168, antioxidant 57, UV-329, hindered amine light stabilizer 770, 2,4-di-tert-butylphenol, and 3,5-methyl ester.

4. The performance research method according to claim 1, characterized in that: The solvent is toluene.

5. The performance research method according to claim 1, characterized in that: The mass ratio of the additive to the solvent is 8:(16-8000).

6. The performance research method according to claim 1, characterized in that: The specific wavelength is 500 nm and / or 425 nm.

7. The performance research method according to claim 1, characterized in that: The light transmittance detection method comprises: pouring the sample into a cuvette, placing it in a spectrophotometer, using a blank solvent as a reference, and measuring the light transmittance at a specific wavelength; The yellow index detection method comprises: installing a transmission target mask on the illumination window of the transmission sample chamber of a CM-5 spectrophotometer, then installing a colorimetric cell containing a sample to be tested on the instrument using a transmission measurement kit, selecting a transmission measurement mode, and testing the yellow index of the sample.

8. The performance research method according to claim 1, characterized in that: In step A) and step B), before each sampling test, the color of the solution sample is observed and recorded.

9. The performance research method according to claim 1, characterized in that: In step B), the periodic sampling and testing is to perform sampling and testing at intervals of a certain period of time, and the time intervals between each time can be the same or different.

10. The performance research method according to claim 1 or 9, characterized in that: In step B), the periodic sampling and testing are respectively performed on the 3rd day, the 7th day, the 15th day, the 30th day, the 60th day and one year.

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