A method for screening antioxidants in styrene butadiene resin

Abstract

The application provides a screening method of antioxidants in styrene butadiene resin, which comprises color observation and GPC test on samples added with different antioxidants, judging whether the selected antioxidants in the samples meet the requirements according to the time when the color of the samples changes and the increase rate of the area proportion of macromolecules in the samples, and then obtaining the samples meeting the requirements, and completing the screening of the antioxidants in the styrene butadiene resin. The screening method is short in time, fast in speed, high in efficiency, and very accurate in screening result, and provides a new method for the screening of antioxidants in styrene butadiene resin.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of styrene-butadiene resin, and particularly relates to a screening method for antioxidants in styrene-butadiene resin. BACKGROUND

[0002] Styrene-butadiene resin is a kind of block structure thermoplastic polymer material synthesized by using styrene and butadiene as monomers, alkyl lithium as initiator and adopting anionic solution polymerization technology. The styrene-butadiene resin has high transparency, good impact resistance, small density, excellent processing performance, non-toxicity and other advantages, and is widely applied to various fields such as packaging, medical devices, household appliances, high-grade daily necessities and office supplies.

[0003] There are double bonds in the polybutadiene in the styrene-butadiene resin. The double bonds are easily crosslinked under the influence of external conditions such as shearing, heat and impurities, which will eventually lead to the decrease of the mechanical properties of the styrene-butadiene resin and the color change, and then the crosslinking caused by the thermal oxidation needs to be inhibited by adding appropriate antioxidants. Since there are many types of antioxidants at present, and each type of antioxidant has its unique structure, it is necessary to screen among the many antioxidants to select the type and amount of antioxidant suitable for the prepared styrene-butadiene resin.

[0004] The conventional screening method is to test the yellow index and reflection changes of the styrene-butadiene resin particles under ultraviolet light, sunlight and in an oven (at a temperature of about 105 DEG C) for different time periods, and the screening process is very complex and time-consuming, which is not conducive to industrial production.

[0005] Therefore, it is a technical problem urgently to be solved in the field to develop a screening method for antioxidants in styrene-butadiene resin with short time and accurate results. SUMMARY

[0006] In view of the deficiencies of the prior art, the purpose of the present application is to provide a screening method for antioxidants in styrene-butadiene resin, which comprises color observation and GPC test on samples added with different antioxidants, and determines whether the selected antioxidant in the sample meets the requirements according to the time of color change of the sample and the increase rate of the area ratio of macromolecules in the sample, so as to obtain the sample meeting the requirements and complete the screening of the antioxidants in the styrene-butadiene resin. The screening method is short in time, fast in speed, high in efficiency and accurate in screening results, and provides a new method for the screening of antioxidants in styrene-butadiene resin.

[0007] To achieve this purpose, the following technical solutions are adopted in the present application:

[0008] The present application provides a screening method for antioxidants in styrene-butadiene resin, which comprises the following steps:

[0009] (1) adding different antioxidants in the styrene butadiene resin to obtain a group of samples;

[0010] (2) performing GPC test on each sample in the group of samples respectively to obtain the initial macromolecule area ratio of each sample;

[0011] (3) placing the group of samples in an oven for baking, observing the color change of each sample, recording the color change time of each sample respectively, and performing GPC test on each sample again after baking for 180 minutes to obtain the crosslinking macromolecule area ratio of each sample;

[0012] (4) calculating the macromolecule area ratio increase rate of each sample according to the initial macromolecule area ratio and the crosslinking macromolecule area ratio of each sample;

[0013] (5) determining the sample meeting the requirements according to the color change time and the macromolecule area ratio increase rate of each sample, and completing the screening of the antioxidant in the styrene butadiene resin.

[0014] The screening method of the antioxidant provided by the application firstly prepares samples, and the sample preparation specifically comprises adding different antioxidants in the styrene butadiene resin, and the type and amount of the selected antioxidant can be selected according to experience or convention, and a group of samples added with different types of antioxidants or different amounts of antioxidants are obtained; then GPC test is performed on each sample in the group of samples respectively, and the initial macromolecule area ratio of each sample is obtained from the obtained GPC spectrum (the initial macromolecule area ratio is the volume ratio of the area of the peak with the highest molecular weight in the GPC spectrum to the total area of all peaks); then the group of samples after GPC test are placed in the same oven to ensure the same baking conditions, the color change of each sample is observed, the color change time of each sample is recorded respectively, GPC test is performed on each sample again after baking for 180 minutes, the crosslinking macromolecule area ratio of each sample is obtained (the confirmation method of the crosslinking macromolecule area ratio is the same as that of the initial macromolecule area ratio), and then the macromolecule area ratio increase rate of each sample is calculated according to the initial macromolecule area ratio and the crosslinking macromolecule area ratio of each sample; finally, the sample meeting the requirements is determined according to the color change time and the macromolecule area ratio increase rate of each sample, and the screening of the antioxidant in the styrene butadiene resin is completed.

[0015] It should be noted that the number of specific samples of the group of samples obtained in step (1) is not particularly limited, and can be determined according to the size of the oven and the experience of the antioxidant and styrene-butadiene resin; if the required sample is not obtained at last, the type and amount of antioxidant in the sample with the longest discoloration time and the smallest increase rate of macromolecular area ratio are referred to for adjustment, and the preparation and testing of the sample are re-performed until the required sample is obtained, and the antioxidant meeting the requirements is screened out.

[0016] The screening method provided by the present application includes color observation and GPC testing of samples added with different antioxidants, and whether the selected antioxidant in the sample meets the requirements is judged according to the time of color change of the sample and the increase rate of macromolecular area ratio in the sample, so as to obtain the sample meeting the requirements and complete the screening of the antioxidant in the styrene-butadiene resin; because the longer the sample is in the oven, the higher the macromolecular area ratio is, that is, the more macromolecules in the sample, because the butadiene will crosslink at high temperature for a long time, and the crosslinking will become more and more serious with the increase of time, so the aging resistance of the antioxidant system in the glue solution can be screened, and a better antioxidant ratio is obtained; and the color of the glue solution remains unchanged with the increasing amount of the appropriate antioxidant ratio of the antioxidant; the screening method is time-saving, fast, efficient, and the screening result is very accurate, which provides a new method for the screening of the antioxidant of the styrene-butadiene resin.

[0017] It should be noted that the longest discoloration time in the screening method provided by the present application is tested for 180 min.

[0018] Preferably, the raw material of the styrene-butadiene resin in step (1) comprises styrene and butadiene.

[0019] Preferably, the specific method of adding different antioxidants in the styrene-butadiene resin in step (1) comprises: adding antioxidants of the same type but different amounts in the styrene-butadiene resin respectively, to obtain 6-12 samples with different amounts of antioxidant addition;

[0020] Or adding antioxidants of different types but the same amount in the styrene-butadiene resin respectively, to obtain 6-12 samples with different types of antioxidants.

[0021] Preferably, the solvent for the GPC test in steps (2) and (3) is tetrahydrofuran.

[0022] Preferably, the temperature of the baking in step (3) is 160-180℃, for example, 162℃, 164℃, 166℃, 168℃, 170℃, 172℃, 174℃, 176℃ or 178℃, etc.

[0023] Preferably, the oven is an electric heating constant temperature drying oven.

[0024] Preferably, the specific method of observing the color change of each sample in step (3) comprises: observing the color change of each sample every 30-45 min (for example, 32 min, 34 min, 36 min, 38 min, 40 min, 42 min or 44 min, etc.).

[0025] Preferably, the color change in step (3) is that the color changes from colorless and transparent to yellow.

[0026] Preferably, the increase rate of the macromolecular area ratio in step (4) is calculated according to the formula I:

[0027] The increase rate of the macromolecular area ratio = (the crosslinked macromolecular area ratio - the initial macromolecular area ratio) / the crosslinked macromolecular area ratio x 100% formula I.

[0028] Preferably, the specific conditions for determining the sample meeting the requirements in step (5) are as follows:

[0029] If the color change time > 180 min and the increase rate of the macromolecular area ratio ≤ 5%, it meets the requirements, otherwise it does not meet the requirements.

[0030] As a preferred technical solution of the present application, the screening method specifically comprises the following steps:

[0031] (1) adding different antioxidants in the butadiene styrene resin to obtain a group of samples;

[0032] (2) performing GPC test on each sample in the group of samples respectively to obtain the initial macromolecular area ratio of each sample;

[0033] (3) placing the group of samples in an oven, drying at 160-180℃, observing the color change of each sample every 30-45 min, recording the color change time of each sample as the color change time, and performing GPC test on each sample again after 180 min of drying to obtain the crosslinked macromolecular area ratio of each sample;

[0034] (4) calculating the increase rate of the macromolecular area ratio of each sample according to the initial macromolecular area ratio and the crosslinked macromolecular area ratio of each sample according to the formula I;

[0035] The increase rate of the macromolecular area ratio = (the crosslinked macromolecular area ratio - the initial macromolecular area ratio) / the crosslinked macromolecular area ratio x 100% formula I;

[0036] (5) according to the discoloration time and the increase rate of the macromolecular area proportion of each sample, the sample meeting the requirements is determined, if the discoloration time is greater than 180 min and the molecular weight increase rate is less than or equal to 5%, it is confirmed that the antioxidant added in the sample meets the requirements, otherwise it is confirmed that the antioxidant added in the sample does not meet the requirements, the sample meeting the requirements is determined, and the screening of the antioxidant in the butyl benzene resin is completed.

[0037] Compared with the prior art, the present application has the following beneficial effects:

[0038] The screening method of the antioxidant in the butyl benzene resin provided by the present application includes color observation and GPC test on samples added with different antioxidants, whether the selected antioxidant in the sample meets the requirements is judged according to the time of color change of the sample and the increase rate of the macromolecular area proportion in the sample, and then the sample meeting the requirements is obtained, and the screening of the antioxidant in the butyl benzene resin is completed. The screening method is short in time, fast in speed, high in efficiency, and very accurate in screening result, and provides a new method for screening of the antioxidant in the butyl benzene resin. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 The GPC spectrum obtained by testing sample 1 in example 1 at step (2);

[0040] In the formula, 1-macromolecular absorption peak, 2-other peaks. DETAILED DESCRIPTION

[0041] The technical solutions of the present application will be further described by specific embodiments. Those skilled in the art should understand that the embodiments are only used to help understand the present application, and should not be regarded as specific limitation to the present application.

[0042] Preparation example 1

[0043] A butyl benzene resin, the preparation method thereof comprises the following steps: in a 10L reaction kettle, the maximum pressure of the reaction kettle is 1.6MPa, 6000g of cyclohexane is soaked at 45℃, and then the reaction kettle is purged with nitrogen gas and is ready for use; 4500g of cyclohexane is added into the reaction kettle, the temperature of the reaction kettle is raised to 45℃, then 650g of styrene and 5.923g of butyl lithium (20% concentration) are added, after the peak height, 250g of butadiene is added after 5 minutes of reaction, after the peak temperature, 1.723g of butyl lithium (20% concentration) is added, then 100g of styrene is added, after the peak height, 5 minutes of reaction, 5g of water is added as a terminating agent, and the butyl benzene resin is obtained.

[0044] Example 1

[0045] A screening method of an antioxidant in a butyl benzene resin, the screening method specifically comprises the following steps:

[0046] (1) adding different kinds of antioxidants into the styrene-butadiene resin (preparation example 1) (the formula of each group of antioxidants is shown in Table 1, and the total amount of the antioxidants added is 3000 ppm of the total mass of all the reaction monomers in the styrene-butadiene resin provided in preparation example 1) to obtain a group of samples;

[0047] (2) performing GPC testing on each sample in the group of samples respectively to obtain the initial macromolecule area ratio of each sample;

[0048] (3) placing the group of samples in an oven and drying at 170℃, observing the color change of each sample every 45 min, recording the color change time of each sample, and performing GPC testing on each sample again after 180 min of baking to obtain the macromolecule crosslinking area ratio of each sample;

[0049] (4) calculating the macromolecule area ratio increase rate of each sample according to the initial macromolecule area ratio and the macromolecule crosslinking area ratio of each sample according to the formula I:

[0050] Macromolecule area ratio increase rate = (macromolecule crosslinking area ratio - initial macromolecule area ratio) / macromolecule crosslinking area ratio x 100% Formula I;

[0051] (5) determining the sample meeting the requirements according to the color change time and the macromolecule area ratio increase rate of each sample, if the color change time > 180 min and the molecular weight increase rate ≤ 5%, it is confirmed that the antioxidant added in the sample meets the requirements, otherwise it is confirmed that the antioxidant added in the sample does not meet the requirements, the sample meeting the requirements is determined, and the screening of the antioxidant in the styrene-butadiene resin is completed.

[0052] The group of samples provided in example 1 contains 6 samples, and the types and proportions of the antioxidants in the 6 samples are shown in Table 1:

[0053] Table 1

[0054] Group Antioxidant formulation (mass ratio) Sample 1 No antioxidant added Sample 2 Antioxidant 1010 and antioxidant 1076 (1 : 1) Sample 3 Antioxidant 1010 and antioxidant 1076 (1 :2) Sample 4 Antioxidant 1010 and antioxidant 1076 (2:2) Sample 5 Antioxidant 1010 and antioxidant 1076 (1.5:2) Sample 6 Antioxidant 1010, antioxidant 1076 and antioxidant 168 (1 : 1 : 1) Sample 7 Antioxidant 1010, antioxidant 1076 and antioxidant 168 (1 :2: 1)

[0055] The color change time and the macromolecule area ratio of the 6 samples provided in example 1 are shown in Table 2:

[0056] Table 2

[0057]

[0058]

[0059] In Table 2, the macromolecule initial area ratio and the macromolecule crosslinking area ratio are both confirmed according to the GPC spectrum; for example, the GPC spectrum of the above sample 1 after step (2) is shown in Figure 1 , wherein 1 represents a macromolecule absorption peak, and 2 represents other peaks; the area ratio of the macromolecule absorption peak at 1 is the initial macromolecule area ratio of sample 1;

[0060] In the present application, since the solvent for the GPC test is THF, sample 1 is completely crosslinked after being placed in the oven for 180 min and cannot be dissolved for testing, and thus the macromolecule crosslinking area ratio is recorded as 100%.

[0061] As can be seen from Table 1, the discoloration time of sample 7 is >180 min and the macromolecule area ratio increase rate after 180 min is less than 5%, which meets the requirements, and thus it is confirmed that the antioxidant formula of adding antioxidants 1010, 1076 and 168 in a mass ratio of 1:2:1 in sample 7 meets the antioxidant requirements of the butylphenyl resin provided in Preparation Example 1.

[0062] Example 2

[0063] A screening method for antioxidants in a butylphenyl resin, which specifically comprises the following steps:

[0064] (1) adding antioxidants of the same type and different amounts (the antioxidants are a combination of antioxidants 1010, 1076 and 168 in a mass ratio of 1:2:1, and the specific addition amount of each group is shown in Table 1) in a butylphenyl resin (Preparation Example 1) to obtain a group of samples;

[0065] (2) performing GPC test on each sample in the group of samples respectively to obtain the initial macromolecule area ratio of each sample;

[0066] (3) placing each sample in the group of samples in an oven for drying at 170℃, observing the color change of each sample every 45 min, recording the time for each sample to turn yellow as the discoloration time, and performing GPC test on each sample again after 180 min of baking to obtain the macromolecule crosslinking area ratio of each sample;

[0067] (4) calculating the macromolecule area ratio increase rate of each sample according to the initial macromolecule area ratio and the macromolecule crosslinking area ratio of each sample according to the formula I shown below:

[0068] Macromolecule area ratio increase rate = (macromolecule crosslinking area ratio - initial macromolecule area ratio) / macromolecule crosslinking area ratio x 100% formula I;

[0069] (5) According to the discoloration time and the increase rate of the macromolecule area ratio of each sample, the sample meeting the requirements is determined. If the discoloration time is >180 min and the molecular weight increase rate is ≤5%, it is confirmed that the antioxidant added in the sample meets the requirements, otherwise, it is confirmed that the antioxidant added in the sample does not meet the requirements, the sample meeting the requirements is determined, and the screening of the antioxidant in the butadiene styrene resin is completed.

[0070] The group of samples provided in the embodiment contains 11 samples, the addition amount of the antioxidant in each sample (calculated based on the total mass of all reaction monomers in the butadiene styrene resin provided in Preparation Example 1 being 100%) and the test obtained macromolecule area ratio are shown in Table 3:

[0071] Table 3

[0072]

[0073] In Table 3, the initial macromolecule area ratio and the crosslinked macromolecule area ratio are confirmed according to the GPC spectrum, and in the present application, since the solvent for the GPC test is THF, sample 1 and sample 2 are completely crosslinked after being placed in the oven for 180 min and cannot be dissolved for testing, and thus the macromolecule area ratio is recorded as 100%.

[0074] As can be seen from Table 3, the discoloration time of sample 10 and sample 11 is >180 min and the increase rate of the macromolecule area ratio after 180 min is less than 5%.

[0075] The applicant declares that the present application is illustrated by the above-mentioned embodiment as a screening method of an antioxidant in a butadiene styrene resin, but the present application is not limited to the above-mentioned embodiment, i.e. it does not mean that the present application must rely on the above-mentioned embodiment to be implemented. It should be understood by those skilled in the art that any improvement of the present application, equivalent replacement of each raw material of the product of the present application, addition of auxiliary ingredients, selection of specific modes, etc. fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for screening antioxidants in a styrene butadiene resin, characterized by, The screening method comprises the following steps: (1) adding different antioxidants into the styrene-butadiene resin to obtain a group of samples; (2) performing GPC test on each sample in the group of samples respectively to obtain the initial macromolecular area ratio of each sample, wherein the initial macromolecular area ratio is the volume ratio of the area of the peak with the highest molecular weight in the GPC spectrum in the total peak area; (3) placing the group of samples into an oven for baking, observing the color change of each sample, recording the time when the color of each sample changes as the color change time respectively, and performing GPC test on each sample again after baking for 180 minutes to obtain the crosslinked macromolecular area ratio of each sample, wherein the confirmation method of the crosslinked macromolecular area ratio is the same as that of the initial macromolecular area ratio; (4) calculating the macromolecular area ratio increase rate of each sample according to the initial macromolecular area ratio and the crosslinked macromolecular area ratio of each sample; (5) determining the sample meeting the requirements according to the color change time and the macromolecular area ratio increase rate of each sample, and completing the screening of the antioxidants in the styrene-butadiene resin. The specific conditions for determining the sample meeting the requirements in step (5) are as follows: If the color change time is greater than 180 minutes and the macromolecular area ratio increase rate is less than or equal to 5%, the sample meets the requirements, otherwise, the sample does not meet the requirements.

2. The screening method according to claim 1, characterized in that, The raw materials of the styrene-butadiene resin in step (1) comprise styrene and butadiene.

3. The screening method according to claim 1, characterized by, The specific method for adding different antioxidants into the styrene-butadiene resin in step (1) comprises: adding antioxidants of the same type but with different dosages into the styrene-butadiene resin to obtain 6-12 samples with different antioxidant dosages; Or adding antioxidants of different types but with the same dosage into the styrene-butadiene resin to obtain 6-12 samples with different antioxidant types.

4. The screening method according to claim 1, characterized by, The solvents for the GPC test in steps (2) and (3) are both tetrahydrofuran.

5. The screening method according to claim 1, wherein, The baking temperature in step (3) is 160-180 DEG C.

6. The screening method according to claim 1, wherein, The oven is an electric heating constant temperature drying oven.

7. The screening method according to claim 1, wherein The specific method for observing the color change of each sample in step (3) comprises: observing the color change of each sample every 30-45 minutes.

8. The screening method according to claim 1, wherein, The color change specifically refers to the change from colorless and transparent to yellow.

9. The screening method according to claim 1, wherein, The macromolecular area ratio increase rate is calculated according to the formula I: Macromolecular area ratio increase rate=(crosslinked macromolecular area ratio-initial macromolecular area ratio) / crosslinked macromolecular area ratio*100% formula I.

10. The screening method according to claim 1, wherein, The screening method specifically comprises the following steps: (1) adding different antioxidants into the styrene-butadiene resin to obtain a group of samples; (2) performing GPC test on each sample in the group of samples respectively to obtain the initial macromolecular area ratio of each sample; (3) placing the group of samples into an oven, baking at 160-180 DEG C, observing the color change of each sample every 30-45 minutes, recording the time when the color of each sample changes as the color change time respectively, and performing GPC test on each sample again after baking for 180 minutes to obtain the crosslinked macromolecular area ratio of each sample; (4) According to the initial molecular area proportion of macromolecules and the crosslinking area proportion of macromolecules in each sample, the increase rate of macromolecular area proportion in each sample is calculated according to the formula I; The increase rate of macromolecular area proportion = (the crosslinking area proportion of macromolecules - the initial area proportion of macromolecules) / the crosslinking area proportion of macromolecules × 100% formula I; (5) According to the discoloration time and the increase rate of macromolecular area proportion of each sample, the sample meeting the requirements is determined, if the discoloration time > 180 min, and the increase rate of macromolecular area proportion ≤ 5%, it is confirmed that the antioxidant added in the sample meets the requirements, otherwise it is confirmed that the antioxidant added in the sample does not meet the requirements, the sample meeting the requirements is determined, and the screening of the antioxidant in the butadiene styrene resin is completed.

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