Separation and quantification method of starch-based adhesive

Abstract

The invention relates to the technical field of separation and quantification, in particular to a separation and quantification method of a starch-based adhesive, which is used for separating starch, polyvinyl alcohol and polyacrylamide in the starch-based adhesive according to the solubility difference of the starch, polyvinyl alcohol and polyacrylamide in a solvent. The accuracy of the method is verified through qualitative analysis and recovery rate calculation of the infrared spectrum of the separated product.

Description

Technical Field

[0001] The invention relates to the technical field of separation quantification, and in particular to a separation quantification method for a starch-based adhesive. Background Art

[0002] Starch is a renewable resource with good adhesion and film-forming properties. Adhesives produced with starch as raw material have the characteristics of high strength, no pollution, low cost, and non-toxicity, and are widely used in various application fields such as paper, wood, textiles, and packaging materials. In recent years, starch-based adhesives are often used as adhesives for corrugated box production. The most commonly used process is to improve its water resistance, heat resistance, and bonding strength through blending modification, among which polyvinyl alcohol modification and polyacrylamide modification are more common.

[0003] Starch, polyvinyl alcohol, and polyacrylamide are all water-soluble substances, which can make starch adhesives evenly mixed in aqueous solutions, so that this adhesive will not emit harmful substances during application. However, it also leads to the problem of difficulty in separating raw materials during formula analysis of this starch adhesive. It is difficult to identify whether polyvinyl alcohol and polyacrylamide are present in the starch adhesive, and it is also difficult to quantitatively analyze the three. Traditional analysis and separation methods rely on the different particle sizes of the three, and perform rough separation by sieving. However, since the particle size of each substance often exists in a certain range, this method has a large error.

[0004] Therefore, there is an urgent need in the market for a separation and quantification method that can accurately separate and quantify the content of various substances in starch-based adhesives. Summary of the invention

[0005] In view of the problems existing in the prior art, the purpose of the present invention is to obtain a separation and quantification method that can accurately separate and quantify the content of various substances in a starch-based adhesive.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] In one aspect, the present invention provides a method for separating and quantifying a starch-based adhesive, comprising the following steps:

[0008] S1. Weigh a starch-based adhesive, add a solvent, and heat for 0.5-1.5 hours to obtain a mixture;

[0009] S2, filtering the mixture obtained in step S1 with filter paper to obtain soluble matter, wherein the upper layer of the filter paper is a swollen transparent spherical gel and an insoluble white powder, drying the swollen transparent spherical gel to obtain sample 1, and drying the insoluble white powder to obtain sample 2;

[0010] S3, drying the soluble matter obtained in step S2 to obtain sample 3;

[0011] S4. Use an infrared spectrometer to detect the starch-based adhesive, sample 1 and sample 2 obtained in step S2, and sample 3 obtained in step S3 to obtain an infrared spectrum of each sample, determine the type of each sample according to the peak position of each standard and the infrared matching spectrum, and then calculate the content of each sample in the starch-based adhesive according to the mass of each sample.

[0012] In the prior art, the analysis and separation methods of starch-based adhesives often rely on the different particle sizes of the three, and perform rough separation by sieving. However, since the particle sizes of various substances often exist in a certain range, this method has a large error and cannot achieve accurate qualitative and quantitative analysis. Based on this, the present invention proposes a separation and quantitative analysis method that can accurately separate and quantify the content of various substances in starch-based adhesives. The method utilizes the difference in solubility of starch, polyvinyl alcohol and polyacrylamide in the starch-based adhesive in the solvent to perform qualitative and quantitative analysis, and verifies the accuracy of the method by infrared spectroscopy verification and recovery calculation of the separated products.

[0013] In some embodiments, the method for preparing the starch-based adhesive comprises the following steps: adding starch, polyacrylamide, and polyvinyl alcohol into a high-speed mixer and stirring at room temperature for 30-60 minutes.

[0014] Preferably, the rotation speed of the high-speed mixer is 500-800 rpm.

[0015] In some embodiments, the mass ratio of starch, polyacrylamide, and polyvinyl alcohol is 1:(0.01-0.3):(0.015-0.4).

[0016] In some embodiments, the operation of taking out the transparent spherical gel specifically comprises the following steps: using a solvent to rinse the surface of the transparent spherical gel during the process of taking out the transparent spherical gel.

[0017] The present application can further improve the accuracy of the test results by using a solvent to rinse the transparent spherical gel during the process of removing the transparent spherical gel. This may be because the transparent spherical gel is prone to adhere to some insoluble matter of smaller particle size that is difficult to distinguish with the naked eye when it is removed, which may lead to inaccurate test results. In addition, the present application can increase the amount of solvent by adding the operation of using a solvent to rinse the transparent spherical gel, thereby making it easier to separate the insoluble matter and the soluble matter, which is conducive to improving the separation effect.

[0018] In some embodiments, the solvent is 1,3-butanediol and / or propylene glycol.

[0019] In some embodiments, the mass ratio of the starch-based adhesive to the solvent in step S1 is 1:(30-50).

[0020] In some embodiments, the transparent spherical gel has a diameter of 0.5-2.5 mm.

[0021] In some embodiments, the heating temperature in step S1 is 175-190°C.

[0022] The present application found that using 1,3-butanediol and / or propylene glycol as solvents for starch adhesives unexpectedly caused the substances in the starch adhesive to appear in three states, soluble, insoluble, and gel-like swollen substances, which provided the possibility for accurate qualitative and quantitative analysis of starch-based adhesives. The possible reason is that polyvinyl alcohol molecules contain a large number of hydroxyl groups, which are polar and can form hydrogen bonds with polar solvents. 1,3-Butanediol or propylene glycol are both polar solvents, so they can form hydrogen bonds with the hydroxyl groups of polyvinyl alcohol to promote the dissolution of polyvinyl alcohol; while polyacrylamide contains a large number of cross-linked structures that make it difficult to dissolve in 1,3-butanediol or propylene glycol, but the molecular volume of the two solvents is relatively small, and it is easy to enter the gaps or cavities of polyacrylamide to swell the polyacrylamide. Therefore, 1,3-butanediol and / or propylene glycol as solvents for starch adhesives can significantly improve the separation efficiency of the three substances and improve the accuracy of the test data. However, the gel-like swollen substance is often adhered to the insoluble substance and is difficult to separate. The present application can successfully separate the three substances by limiting the mass ratio of the starch-based adhesive and the solvent, the heating temperature, the heating time and the diameter of the transparent spherical gel-like substance. This may be because the swelling degree of polyacrylamide can be regulated by adjusting the mass ratio of the starch-based adhesive and the solvent, the heating temperature and the heating time, and limiting the diameter of the transparent spherical gel can make the polyacrylamide easier to remove and less likely to carry out the insoluble substance.

[0023] In some embodiments, the drying temperature in step S2 is 55-65° C. and the drying time is 4-6 hours.

[0024] In some embodiments, the drying temperature in step S3 is 65-75° C. and the drying time is 6-8 hours.

[0025] During the testing process, the present application found that the sum of the masses of the three substances after separation often did not correspond to the initial mass of the starch adhesive. The present application unexpectedly discovered that accurate quantification can be achieved by limiting the drying temperature and time. This may be because polyacrylamide or polyvinyl alcohol will decompose or absorb water during the drying process, resulting in inaccurate quantitative results. Therefore, the accuracy of the quantitative results can be improved by adjusting the drying time and temperature.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The present invention proposes a separation and quantification method that can accurately separate and quantify the content of various substances in starch-based adhesives. The method utilizes the difference in solubility of starch, polyvinyl alcohol and polyacrylamide in solvents to perform qualitative and quantitative analysis on them, and verifies the accuracy of the method by infrared spectroscopy verification and recovery rate calculation of the separation products.

[0028] (2) The present invention can further improve the accuracy of the test results by using a solvent rinse operation in the process of removing the transparent spherical gel, and the present application can increase the amount of solvent by adding the operation of using a solvent to rinse the transparent spherical gel, thereby making it easier to separate the insoluble matter and the soluble matter, which is beneficial to improving the separation effect.

[0029] (3) The present invention preferably uses 1,3-butanediol and / or propylene glycol as the solvent of the starch adhesive, so that the substances in the starch adhesive can appear in three states, namely, soluble matter, insoluble matter and gel-like swollen matter, which provides the possibility for achieving accurate qualitative and quantitative analysis of starch-based adhesives.

[0030] (4) The present invention can control the swelling degree of polyacrylamide by limiting the mass ratio of starch-based adhesive and solvent, heating temperature and time, and can make polyacrylamide easier to remove and less likely to carry out insoluble substances by limiting the diameter of the transparent spherical gel, thereby successfully separating the three substances. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The infrared spectrum and infrared matching spectrum of the starch-based adhesive in Example 1;

[0032] Figure 2 The infrared spectrum and infrared matching spectrum of sample 1 in Example 1;

[0033] Figure 3 The infrared spectrum and infrared matching spectrum of sample 2 in Example 1;

[0034] Figure 4 It is the infrared spectrum and infrared matching spectrum of sample 3 in Example 1. DETAILED DESCRIPTION

[0035] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following embodiments are examples of the present invention and are only used to illustrate the present invention, but not to limit the present invention. Other combinations and various modifications within the concept of the present invention may be performed without departing from the spirit or scope of the present invention.

[0036] The compounds and related reagents used in the following examples and comparative examples can all be purchased from the market.

[0037] Preparation Example 1

[0038] The preparation method of a starch-based adhesive comprises the following steps: adding 86.96 g of starch, 4.34 g of polyacrylamide, and 8.70 g of polyvinyl alcohol into a high-speed mixer, and stirring at a rotation speed of 600 rpm at room temperature for 45 minutes to obtain a starch-based adhesive.

[0039] Example 1

[0040] A quantitative separation method for a starch-based adhesive comprises the following steps:

[0041] S1, weigh 4 g of starch-based adhesive, record the mass as m1, add 160 g of 1,3-butanediol, and heat at 180° C. for 1 h to obtain a mixture;

[0042] S2, filtering the mixture obtained in step S1 with filter paper, the upper layer of the filter paper is a swollen transparent spherical gel and an insoluble white powder, taking out a transparent spherical gel with a diameter of 0.5-2.5 mm, and washing the surface of the transparent spherical gel with 1,3-butanediol during the process of taking out the transparent spherical gel, filtering the washing liquid with the filter paper, drying the transparent spherical gel at 60° C. for 5 h to obtain sample 1, weighing the mass and recording it as m2; taking the insoluble white powder and drying it to obtain sample 2, the mass of which is recorded as m3;

[0043] S3, drying the soluble matter obtained in step S2 at 70°C for 7h to obtain sample 3, with the mass recorded as m4;

[0044] S4. Use an infrared spectrometer to detect the starch-based adhesive, sample 1 and sample 2 obtained in step S2, and sample 3 obtained in step S3 to obtain an infrared spectrum of each sample, determine the type of each sample according to the peak position of each standard and the infrared matching spectrum, and then calculate the content of each sample in the starch-based adhesive according to the mass of each sample. The content of sample 1 is m2 / m1, the content of sample 2 is m3 / m1, and the content of sample 3 is m4 / m1.

[0045] Example 2

[0046] A quantitative separation method for a starch-based adhesive comprises the following steps:

[0047] S1, weigh 4 g of starch-based adhesive, record the mass as m1, add 160 g of 1,3-butanediol, and heat at 175° C. for 1.5 h to obtain a mixture;

[0048] S2, filtering the mixture obtained in step S1 with filter paper, the upper layer of the filter paper is a swollen transparent spherical gel and an insoluble white powder, taking out a transparent spherical gel with a diameter of 0.5-2.5 mm, and washing the surface of the transparent spherical gel with 1,3-butanediol during the process of taking out the transparent spherical gel, filtering the washing liquid with the filter paper, drying the transparent spherical gel at 55° C. for 6 h to obtain sample 1, weighing the mass and recording it as m2; taking the insoluble white powder and drying it to obtain sample 2, the mass of which is recorded as m3;

[0049] S3, drying the soluble matter obtained in step S2 at 65°C for 8h to obtain sample 3, with the mass recorded as m4;

[0050] S4. Use an infrared spectrometer to detect the starch-based adhesive, sample 1 and sample 2 obtained in step S2, and sample 3 obtained in step S3 to obtain an infrared spectrum of each sample, determine the type of each sample according to the peak position of each standard and the infrared matching spectrum, and then calculate the content of each sample in the starch-based adhesive according to the mass of each sample. The content of sample 1 is m2 / m1, the content of sample 2 is m3 / m1, and the content of sample 3 is m4 / m1.

[0051] Example 3

[0052] A quantitative separation method for a starch-based adhesive comprises the following steps:

[0053] S1, weigh 4 g of starch-based adhesive, record the mass as m1, add 160 g of 1,3-butanediol, and heat at 190° C. for 0.5 h to obtain a mixture;

[0054] S2, filtering the mixture obtained in step S1 with filter paper, the upper layer of the filter paper is a swollen transparent spherical gel and an insoluble white powder, taking out a transparent spherical gel with a diameter of 0.5-2.5 mm, and washing the surface of the transparent spherical gel with 1,3-butanediol during the process of taking out the transparent spherical gel, filtering the washing liquid with the filter paper, drying the transparent spherical gel at 65° C. for 4 h to obtain sample 1, weighing the mass and recording it as m2; taking the insoluble white powder and drying it to obtain sample 2, the mass of which is recorded as m3;

[0055] S3, drying the soluble matter obtained in step S2 at 75°C for 6h to obtain sample 3, with the mass recorded as m4;

[0056] S4. Use an infrared spectrometer to detect the starch-based adhesive, sample 1 and sample 2 obtained in step S2, and sample 3 obtained in step S3 to obtain an infrared spectrum of each sample, determine the type of each sample according to the peak position of each standard and the infrared matching spectrum, and then calculate the content of each sample in the starch-based adhesive according to the mass of each sample. The content of sample 1 is m2 / m1, the content of sample 2 is m3 / m1, and the content of sample 3 is m4 / m1.

[0057] Example 4

[0058] A method for separating and quantifying a starch-based adhesive and a method for preparing the same, wherein the specific implementation manner is the same as that of Example 1, except that the amount of 1,3-butanediol added is 20 g.

[0059] Example 5

[0060] A method for separating and quantifying a starch-based adhesive and a method for preparing the same, wherein the specific implementation manner is the same as that of Example 1, except that the heating temperature in step S1 is 150°C.

[0061] Example 6

[0062] A method for separating and quantifying a starch-based adhesive and a method for preparing the same, wherein the specific implementation manner is the same as that of Example 1, except that the drying temperature in step S2 is 80°C.

[0063] Example 7

[0064] A method for separating and quantifying a starch-based adhesive and a method for preparing the same, the specific implementation manner is the same as that of Example 1, except that the drying temperature in step S3 is 100°C.

[0065] Example 8

[0066] A method for separating and quantifying a starch-based adhesive and a method for preparing the same comprise the following steps:

[0067] S1, weigh 4 g of starch-based adhesive, record the mass as m1, add 160 g of 1,3-butanediol, and heat at 180° C. for 1 h to obtain a mixture;

[0068] S2, filtering the mixture obtained in step S1 with filter paper, the upper layer of the filter paper is swollen transparent spherical gel and insoluble white powder, taking out the transparent spherical gel with a diameter of 0.5-2.5 mm, not using 1,3-butanediol to rinse the surface of the transparent spherical gel during the process of taking out the transparent spherical gel, drying the transparent spherical gel at 60° C. for 5 h to obtain sample 1, weighing the mass and recording it as m2; taking the insoluble white powder and drying it to obtain sample 2, the mass of which is recorded as m3;

[0069] S3, drying the soluble matter obtained in step S2 at 70°C for 7h to obtain sample 3, with the mass recorded as m4;

[0070] S4. Use an infrared spectrometer to detect the starch-based adhesive, sample 1 and sample 2 obtained in step S2, and sample 3 obtained in step S3 to obtain an infrared spectrum of each sample, determine the type of each sample according to the peak position of each standard and the infrared matching spectrum, and then calculate the content of each sample in the starch-based adhesive according to the mass of each sample. The content of sample 1 is m2 / m1, the content of sample 2 is m3 / m1, and the content of sample 3 is m4 / m1.

[0071] Performance Testing

[0072] (1) The performance of the sample obtained in Example 1 was tested using a Fourier transform infrared spectrometer:

[0073] Figure 1 The infrared spectrum and infrared matching spectrum of starch-based adhesives are shown in Figure 3118cm -1 、1147cm -1 、1076cm -1 、996cm -1 、850cm -1 The peak at 1633cm reflects the information of starch and matches the infrared spectrum of starch. Since both polyvinyl alcohol and starch have polyhydroxy structures, the starch information completely covers the polyvinyl alcohol information when it is strong, and it is impossible to distinguish whether polyvinyl alcohol exists in the infrared spectrum. -1 The peak at may reflect the information of polyacrylamide or it may be the peak of starch. Figure 2 The infrared spectrum and infrared matching spectrum of sample 1 are shown in Figure 1. -1 、1651cm -1 It is the characteristic peak of the amide bond and matches the infrared spectrum of polyacrylamide, proving that sample 1 is polyacrylamide. Figure 3 The infrared spectrum and infrared matching spectrum of sample 2 are shown in Figure 3, where 3278 cm -1 、2929cm -1 、1335cm -1 、1076cm -1 、848cm -1 The peak at 1633cm reflects the information of starch and matches the infrared spectrum of starch. -1 There is no peak nearby, indicating that polyacrylamide is completely separated. Figure 4 The infrared spectrum and infrared matching spectrum of sample 3 are shown in Figure 1. -1 、1375cm -1 、1268cm -1 、595cm -1The characteristic peak of polyvinyl alcohol is obtained, and the infrared spectrum of polyvinyl alcohol is matched, proving that sample 3 is polyvinyl alcohol. It can be seen that the present invention successfully separates starch, polyvinyl alcohol and polyacrylamide in the starch adhesive.

[0074] (2) Calculate the content of the samples obtained in each embodiment in the starch adhesive. The results are shown in Table 1:

[0075] Table 1

[0076]

[0077]

[0078] It can be seen from the data in Table 1 that the separation and quantification method of the starch-based adhesive in Examples 1-3 of the present invention can achieve accurate quantification. From the comparison between Examples 4 and 5 and Example 1, it can be seen that changing the ratio of 1,3-butanediol and starch-based adhesive or the heating temperature will make polyacrylamide less likely to swell, resulting in a low content of polyacrylamide and a high content of starch; from the comparison between Example 6 and Example 1, it can be seen that changing the drying temperature in step S2 will cause the polyacrylamide to degrade, resulting in inaccurate quantification; from the comparison between Example 7 and Example 1, it can be seen that changing the drying temperature in step S3 will cause the polyvinyl alcohol segment to degrade, resulting in inaccurate quantification; from the comparison between Example 8 and Example 1, it can be seen that not using solvent for cleaning in the process of taking the transparent spherical gel will cause the polyacrylamide content to be high and the starch content to be low.

[0079] The above implementation modes are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A quantitative separation method for starch-based adhesives, characterized in that: The following steps are involved: S1. Weigh a starch-based adhesive, add a solvent, and heat for 0.5-1.5 hours to obtain a mixture; S2, filtering the mixture obtained in step S1 with filter paper to obtain soluble matter, wherein the upper layer of the filter paper is a swollen transparent spherical gel and an insoluble white powder, drying the swollen transparent spherical gel to obtain sample 1, and drying the insoluble white powder to obtain sample 2; S3, drying the soluble matter obtained in step S2 to obtain sample 3; S4. Use an infrared spectrometer to detect the starch-based adhesive, sample 1 and sample 2 obtained in step S2, and sample 3 obtained in step S3 to obtain an infrared spectrum of each sample, determine the type of each sample according to the peak position of each standard and the infrared matching spectrum, and then calculate the content of each sample in the starch-based adhesive according to the mass of each sample.

2. The method for separating and quantifying starch-based adhesives according to claim 1, characterized in that: The preparation method of the starch-based adhesive comprises the following steps: adding starch, polyacrylamide and polyvinyl alcohol into a high-speed mixer and stirring at room temperature for 30-60 minutes to obtain the adhesive.

3. The method for separating and quantifying starch-based adhesives according to claim 2, characterized in that: The mass ratio of the starch, polyacrylamide and polyvinyl alcohol is 1:(0.01-0.3):(0.015-0.4).

4. The method for separating and quantifying starch-based adhesives according to claim 1, characterized in that: The operation of taking out the transparent spherical gel specifically comprises the following steps: in the process of taking out the transparent spherical gel, washing the surface of the transparent spherical gel with a solvent.

5. The quantitative separation method of starch-based adhesive according to claim 1 or 4, characterized in that: The solvent is 1,3-butanediol and / or propylene glycol.

6. The method for separating and quantifying starch-based adhesives according to claim 1, characterized in that: The mass ratio of the starch-based adhesive to the solvent in step S1 is 1:(30-50).

7. The method for separating and quantifying starch-based adhesives according to claim 1, characterized in that: The diameter of the transparent spherical gel is 0.5-2.5 mm.

8. The method for separating and quantifying starch-based adhesives according to claim 1, characterized in that: The heating temperature in step S1 is 175-190°C.

9. The method for separating and quantifying starch-based adhesives according to claim 1, characterized in that: The drying temperature in step S2 is 55-65° C. and the drying time is 4-6 hours.

10. The method for separating and quantifying starch-based adhesives according to claim 1, characterized in that: The drying temperature in step S3 is 65-75° C. and the drying time is 6-8 hours.

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