Degradable hot melt adhesive and preparation method thereof

Abstract

The invention relates to the technical field of preparation of degradable hot melt adhesives, in particular to a degradable hot melt adhesive and a preparation method thereof.The preparation method comprises the steps that modified starch powder and other adhesive preparing components are added into a reaction kettle to be mixed and melted to prepare a hot melt adhesive body, and the prepared hot melt adhesive body is extruded and divided into a plurality of adhesive strip sections; pre-extruding each rubber strip section, determining the contour change condition of the rubber strip sections according to the images of each rubber strip section before and after pre-extruding so as to screen component enrichment abnormal rubber strip sections, determining a plurality of feature point positions for the abnormal rubber strip sections according to a preset interval distance, and instantaneously heating each feature point position, according to the color change condition of each feature point, the abnormal component enrichment category of the adhesive tape is judged so as to select an adjustment mode for preparation and processing of the hot melt adhesive, so that the preparation and processing mode of the hot melt adhesive is adjusted according to the mixing condition of the modified starch powder and other adhesive preparation components; the quality detection precision of the degradable hot melt adhesive and the stability of continuous preparation are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of degradable hot melt adhesive, and in particular to a degradable hot melt adhesive and a preparation method thereof. Background Art

[0002] In today's society, environmental awareness is increasing. Traditional hot melt adhesives are mainly composed of non-degradable petroleum-based polymers, which are difficult to decompose in the natural environment, causing serious "white pollution" problems. A large number of waste hot melt adhesive products are accumulated in the soil or water, which not only affects the appearance, but also poses a great threat to the balance of the ecosystem. New degradable hot melt adhesives have emerged;

[0003] However, the existing degradable hot melt adhesives still face many challenges in terms of performance and preparation process. On the one hand, the bonding performance of some degradable hot melt adhesives is not ideal. The bonding strength of degradable hot melt adhesives based solely on starch is relatively low, which cannot meet the application scenarios with high requirements for bonding strength. On the other hand, the processing performance of degradable materials in the preparation of hot melt adhesives also needs to be improved. The thermal stability of degradable hot melt adhesives is usually low, which affects the consistency of their quality and performance. The rheological properties of degradable hot melt adhesives are also relatively complex, and it is more difficult to control the process parameters during the preparation process, making it difficult to achieve efficient and stable industrial production. Therefore, it is a technical problem that needs to be solved urgently to quickly detect the mixing of modified starch powder and other adhesive making ingredients and improve the quality and stability of degradable hot melt adhesives.

[0004] For example, the Chinese patent authorization announcement number is: CN116908051B, which discloses a method for detecting the flow properties of hot melt adhesive, including: placing the hot melt adhesive sample to be tested in a transparent container, and placing the transparent container on the sample table of a thermomechanical analyzer; performing temperature control operation on the hot melt adhesive sample to be tested through the temperature control program of the thermomechanical analyzer; performing viscosity detection on the hot melt adhesive sample through a Brookfield viscometer at different temperatures to obtain a temperature-viscosity curve of the hot melt adhesive sample; selecting a qualified hot melt adhesive sample, repeating the above steps to obtain a standard temperature-viscosity curve of the qualified hot melt adhesive sample; and judging whether the flow properties of the hot melt adhesive sample to be tested are qualified according to the temperature-viscosity curve and the standard temperature-viscosity curve.

[0005] The prior art still has the following problems:

[0006] The prior art does not take into account that during the preparation of the degradable hot melt adhesive, the difference in polarity between the modified starch and other adhesive making ingredients causes poor melt mixing uniformity, which affects the fluidity of the hot melt adhesive. The prior art cannot adaptively adjust the preparation and processing method of the hot melt adhesive according to the mixing of the modified starch powder and other adhesive making ingredients, which affects the quality detection accuracy of the hot melt adhesive and the stability of continuous preparation. Summary of the invention

[0007] To this end, the present invention provides a degradable hot melt adhesive and a preparation method thereof, so as to overcome the problem that the prior art cannot adaptively adjust the preparation and processing method of the hot melt adhesive according to the mixing condition of the modified starch powder and other adhesive making ingredients, thus affecting the quality detection accuracy of the hot melt adhesive and the stability of continuous preparation.

[0008] To achieve the above object, the present invention provides a method for preparing a degradable hot melt adhesive, comprising:

[0009] Drying and dehydrating the gelatinized modified starch, and grinding the dried and dehydrated modified starch to obtain modified starch powder;

[0010] Adding the modified starch powder and other adhesive-making ingredients into a reaction kettle, mixing and melting to prepare a hot melt adhesive colloid;

[0011] Extruding the prepared hot melt adhesive colloid and dividing the extruded adhesive strip into a plurality of adhesive strip segments at preset intervals, pre-extrude each adhesive strip segment, determining the change of the adhesive strip segment contour according to the image of each adhesive strip segment before and after the pre-extruded image, and screening the adhesive strip segment with abnormal component enrichment based on the change of the adhesive strip segment contour;

[0012] Determine a number of characteristic points at preset intervals for the abnormal rubber strip segment, instantaneously heat each characteristic point at a preset temperature value, and determine the abnormal category of component enrichment of the rubber strip according to the color change of each characteristic point;

[0013] Based on the abnormal category of component enrichment, the adjustment method for the hot melt adhesive preparation process is selected, including:

[0014] adjusting the duration of drying and dehydrating the modified starch according to the first image characterization factor;

[0015] or, adjusting the grinding time of the modified starch according to the second image characterization factor;

[0016] The first image characterization factor and the second image characterization factor are respectively determined based on the difference in color change of the feature point after instantaneous heating.

[0017] Furthermore, the difference in the profile of the rubber strip segment before and after the pre-extrusion is determined including:

[0018] determining a contour image of the rubber strip segment before pre-extrusion as a first contour image, and calculating the first contour image area according to the first contour image;

[0019] determining a contour image of the rubber strip segment after the pre-extrusion for a preset time as a second contour image, and calculating the area of ​​the second contour image according to the second contour image;

[0020] The absolute value of the difference between the first contour image area and the second contour image area is determined as the contour difference amount of the rubber strip segment.

[0021] Furthermore, the process of screening the component-enriched abnormal strip segments includes:

[0022] If the difference in the profile of the rubber strip segment before and after the pre-extrusion does not meet the normal component distribution condition, the rubber strip segment is screened as a rubber strip segment with abnormal component enrichment;

[0023] The normal component distribution condition is that the contour difference does not exceed a preset contour difference threshold.

[0024] Furthermore, determining the color change of the feature point includes:

[0025] Obtaining the grayscale value of each feature point before instantaneous heating and the grayscale value of each feature point after instantaneous heating;

[0026] The absolute value of the difference between the grayscale value of the feature point before instantaneous heating and the grayscale value after instantaneous heating is calculated, and the absolute value of the difference is determined as the feature coefficient of the feature point.

[0027] Further, determining the abnormal enrichment category of the components of the strip includes:

[0028] If the characteristic coefficients of the characteristic points in each abnormal rubber strip segment on the colloid meet the component stratification enrichment condition, the component enrichment abnormal category of the colloid is determined to be the enrichment stratification abnormal category;

[0029] If the characteristic coefficients of the characteristic points in each abnormal colloid strip segment on the colloid do not meet the component stratification enrichment condition, the component enrichment abnormal category of the colloid is determined to be a non-enriched stratification abnormal category.

[0030] Furthermore, the component stratification enrichment condition is that the difference between the characteristic coefficients of adjacent characteristic points does not exceed a preset characteristic coefficient threshold.

[0031] Further, the selected adjustment methods for the hot melt adhesive preparation process include:

[0032] If the component enrichment abnormal category is the enrichment stratification abnormal category, then adjusting the duration of drying and dehydrating the modified starch according to the first image representation factor;

[0033] If the component enrichment abnormal category is the non-enrichment stratification abnormal category, the grinding time of the modified starch is adjusted according to the second image characterization factor.

[0034] Furthermore, the average value of the absolute values ​​of the color change differences of adjacent feature points is determined as the first image characterization factor, and the sum of the maximum absolute value and the minimum absolute value of the color change differences of each feature point is determined as the second image characterization factor.

[0035] Furthermore, the adjustment amount of the time for drying and dehydrating the modified starch is positively correlated with the first image representation factor, and the adjustment amount of the time for grinding the modified starch is positively correlated with the second image representation factor.

[0036] Furthermore, the present invention also provides a degradable hot melt adhesive, comprising the following components in parts by weight: 50 parts of modified starch and 33 to 49 parts of other adhesive-making ingredients;

[0037] Among them, other glue-making ingredients include 9-11 parts of ethylene glycol, 6-8 parts of acetyl triethyl citrate, 4-8 parts of triethyl citrate, 1-2 parts of antioxidant, 3-5 parts of complexing agent, and 10-15 parts of modified rosin.

[0038] Compared with the prior art, the present invention has the beneficial effect that the present invention dries and dehydrates the gelatinized modified starch, grinds the dried and dehydrated modified starch to obtain modified starch powder, adds the modified starch powder and other glue-making ingredients into a reactor for mixing and melting to obtain a hot melt adhesive colloid, extrudes the obtained hot melt adhesive colloid, divides the extruded adhesive strip into a plurality of adhesive strip segments at preset intervals, pre-extrudes each adhesive strip segment, determines the change of the adhesive strip segment profile according to the image of each adhesive strip segment before and after the pre-extrusion, and screens the component enrichment based on the change of the adhesive strip segment profile. For abnormal rubber strip segments, several characteristic points are determined at preset intervals, and each characteristic point is instantaneously heated at a preset temperature value. The abnormal category of component enrichment of the rubber strip is determined according to the color change of each characteristic point. The adjustment method for the preparation and processing of the hot melt adhesive is selected based on the abnormal category of component enrichment. Furthermore, according to the mixing of modified starch powder and other adhesive making ingredients, the uniformity of the distribution of components inside the colloid can be judged, and the preparation and processing method of the hot melt adhesive can be adaptively adjusted, thereby improving the quality detection accuracy of the degradable hot melt adhesive and the stability of continuous preparation.

[0039] In particular, the present invention screens out abnormal rubber strip segments with abnormal component enrichment in the colloid through the difference in contours of the rubber strip segments before and after pre-extrusion. It can be understood that the colloid has a certain rebound ability. Under the condition of applying the same external force, colloids with the same components and uniform mixing should have the same rebound ability, while uneven distribution of components will lead to differences in local mechanical properties and changes in rebound ability, which will cause abnormal rubber strip segments and normal rubber strip segments to exhibit different reactions when subjected to force and deformation. When the contours of the rubber strip segments differ before and after pre-extrusion, it indicates that the rebound ability of the rubber strip segments has changed and the component distribution of the rubber strip segments is uneven. The present invention screens out abnormal rubber strip segments with abnormal component enrichment in the colloid through the difference in contours of the rubber strip segments before and after pre-extrusion, thereby achieving rapid identification of abnormal mixing of modified starch powder and other adhesive-making components, and improving the quality detection accuracy of the degradable hot melt adhesive and the stability of continuous preparation.

[0040] In particular, when the present invention instantaneously heats the characteristic points, the heat will cause the modified starch around the characteristic points to migrate and gather toward the characteristic points. As the modified starch gathers at the characteristic points, the color changes at the characteristic points can accurately reflect the distribution density and dynamic migration characteristics of the modified starch around the characteristic points. By obtaining the color changes of each characteristic point, the distribution characteristics of the modified starch in the abnormal glue strip segment can be intuitively reflected, thereby achieving rapid identification of abnormal mixing of modified starch powder and other glue-making ingredients, thereby improving the quality detection accuracy of the degradable hot melt adhesive and the stability of continuous preparation.

[0041] In particular, the present invention determines the abnormal category of component enrichment of the colloid by the color change of each characteristic point. It can be understood that when the color change of each characteristic point is relatively consistent, the content and distribution of modified starch around the characteristic point are similar. When the color change of each characteristic point is quite different, the amount of modified starch moving to the characteristic point during the heating process is different. The characteristic point with more modified starch distributed around it has a more obvious color change after heating, while the color change of the characteristic point with less modified starch distributed around it is relatively weak, indicating that the content and distribution of modified starch around each point are different. Furthermore, the present invention determines the abnormal category of component enrichment of the colloid by the color change of each characteristic point after instantaneous heating, realizes the rapid identification of abnormal mixing of modified starch powder and other glue-making ingredients, judges the uniformity of the distribution of components inside the colloid, and improves the quality detection accuracy of the degradable hot melt adhesive and the stability of continuous preparation.

[0042] In particular, under the condition of enriched stratification abnormality category, the present invention adjusts the drying and dehydration time of the modified starch according to the first image characterization factor. It can be understood that in the preparation process of degradable hot melt adhesive, if the drying and dehydration time of the modified starch is insufficient, more water molecules will be retained in the starch granules. These water molecules will cause the modified starch to be poorly compatible with other components of the adhesive, resulting in internal component stratification caused by phase separation. By adjusting the drying and dehydration time of the modified starch, the moisture content in the modified starch can be reduced. Furthermore, the preparation and processing method of the hot melt adhesive can be adaptively adjusted according to the mixing of the modified starch powder and other adhesive components, thereby improving the quality detection accuracy of the degradable hot melt adhesive and the stability of continuous preparation.

[0043] In particular, the present invention adjusts the grinding time of the modified starch particles according to the second image characterization factor under the condition of non-enriched stratified abnormal category. It can be understood that under the condition of non-enriched stratified abnormal category, the uneven distribution of modified starch in the characterization colloid is caused by the difference in particle size of the modified starch. The difference in particle size of the modified starch leads to large differences in color changes at each characteristic point. By adjusting the grinding time of the modified starch particles, the particle size of the modified starch is made more uniform, thereby improving the quality detection accuracy of the degradable hot melt adhesive and the stability of continuous preparation.

[0044] In particular, the adjustment amount of the drying and dehydration time for the modified starch in the present invention is positively correlated with the first image characterization factor. It can be understood that by adjusting the drying and dehydration time, the drying degree of the modified starch can be optimized. The larger the first image characterization factor, the larger the average value of the color change difference of each characteristic point, which indicates that the modified starch contains more water. Appropriately extending the drying and dehydration time can remove excess water and make the modified starch more evenly distributed in the subsequent colloid stratification process, thereby improving the quality detection accuracy of the degradable hot melt adhesive and the stability of continuous preparation.

[0045] In particular, the adjustment amount of the grinding time for the modified starch particles in the present invention is positively correlated with the second image characterization factor. It can be understood that the sum of the maximum and minimum values ​​of the color change difference of the characteristic points can overall reflect the degree of heterogeneity of the modified starch particles. When the second image characterization factor is large, it means that there are large differences in the particle size of the modified starch, and a longer grinding time is required to reduce the particle size difference of the modified starch, so that the modified starch is more evenly distributed, thereby improving the quality detection accuracy of the degradable hot melt adhesive and the stability of continuous preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A step diagram of a method for preparing a degradable hot melt adhesive according to an embodiment of the present invention;

[0047] Figure 2 A logic flow chart for screening abnormal component-enriched rubber strip segments according to an embodiment of the present invention;

[0048] Figure 3 A logic flow chart for determining abnormal enrichment categories of components of a rubber strip according to an embodiment of the present invention;

[0049] Figure 4 A logic flow chart for selecting an adjustment method for hot melt adhesive preparation processing according to an embodiment of the present invention. DETAILED DESCRIPTION

[0050] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0051] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0052] It should be noted that, in the description of the present invention, terms such as "upper", "lower", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0053] See also Figure 1 As shown, it is a step diagram of a method for preparing a degradable hot melt adhesive according to an embodiment of the present invention. A method for preparing a degradable hot melt adhesive according to the present invention comprises:

[0054] Step S100, drying and dehydrating the gelatinized modified starch, and grinding the dried and dehydrated modified starch to obtain modified starch powder;

[0055] Step S200, adding the modified starch powder and other adhesive making ingredients into a reaction kettle, mixing and melting to make a hot melt adhesive colloid;

[0056] Step S300, extruding the prepared hot melt adhesive colloid and dividing the extruded adhesive strip into a plurality of adhesive strip segments at preset intervals, pre-extruding each adhesive strip segment, determining the change of the adhesive strip segment contour according to the image of each adhesive strip segment before and after the pre-extrusion, and screening the adhesive strip segment with abnormal component enrichment based on the change of the adhesive strip segment contour;

[0057] Specifically, the preset intervals for dividing the rubber strips into several sections can be set by those skilled in the art according to the detection accuracy requirement. The higher the accuracy requirement, the smaller the preset interval. Preferably, the preset interval can be 80 cm.

[0058] Specifically, the extrusion pressure for pre-extruding each rubber strip segment may be 0.4 MPa.

[0059] Step S400, determining a number of characteristic points at preset intervals for the abnormal rubber strip segment, instantaneously heating each characteristic point at a preset temperature value, and determining the abnormal category of component enrichment of the rubber strip according to the color change of each characteristic point;

[0060] Specifically, the preset interval distances for determining a plurality of characteristic points may be set by those skilled in the art according to the length of the rubber strip segment. Preferably, when the length of the rubber strip segment is 80 cm, the preset interval distance may be 20 cm.

[0061] In practice, each feature point can be instantly heated by spraying high-temperature hot air onto the feature point. The high-temperature hot air is sprayed at a flow rate of 0.1 to 0.5 L / s, the temperature rise amplitude can be set to 15 to 30°C / second, and the heating time can be set to 0.5 to 1.5 seconds.

[0062] Step S500, based on the abnormal category of component enrichment, select an adjustment method for hot melt adhesive preparation and processing, including:

[0063] adjusting the duration of drying and dehydrating the modified starch according to the first image characterization factor;

[0064] or, adjusting the grinding time of the modified starch according to the second image characterization factor;

[0065] The first image characterization factor and the second image characterization factor are respectively determined based on the difference in color change of the feature point after instantaneous heating.

[0066] Specifically, the differences in the profiles of the rubber strip segments before and after pre-extrusion are determined as follows:

[0067] determining a contour image of the rubber strip segment before pre-extrusion as a first contour image, and calculating the first contour image area according to the first contour image;

[0068] determining a contour image of the rubber strip segment after the pre-extrusion for a preset time as a second contour image, and calculating the area of ​​the second contour image according to the second contour image;

[0069] The absolute value of the difference between the first contour image area and the second contour image area is determined as the contour difference amount of the rubber strip segment.

[0070] Specifically, the present invention does not limit the specific method of obtaining the first contour image area and the second contour image area. Preferably, after obtaining the contour image of the rubber strip segment through a camera, an edge algorithm is used to extract the rubber strip contour in the contour image, and image processing software is used to identify the pixel points in the image to obtain the first contour image area and the second contour image area. It will not be repeated here.

[0071] Specifically, the preset time length for completing the pre-extrusion may be 10 seconds.

[0072] Specifically, see Figure 2 As shown, it is a logic flow chart of screening component-enriched abnormal rubber strip segments according to an embodiment of the present invention. The process of screening component-enriched abnormal rubber strip segments includes:

[0073] If the difference in the profile of the rubber strip segment before and after the pre-extrusion does not meet the normal component distribution condition, the rubber strip segment is screened as a rubber strip segment with abnormal component enrichment;

[0074] If the difference in the profile of the rubber strip segment before and after the pre-extrusion meets the normal component distribution condition, the rubber strip segment is not screened;

[0075] The normal component distribution condition is that the contour difference does not exceed a preset contour difference threshold.

[0076] Specifically, the preset contour difference threshold can be set by a person skilled in the art according to the detection accuracy requirement. The higher the accuracy requirement, the smaller the contour difference threshold. Preferably, when the length of the rubber strip segment is 80 cm, the contour difference threshold can be 5 cm. 2 .

[0077] The present invention screens out abnormal rubber strip segments with abnormal component enrichment in the colloid through the difference in contours of the rubber strip segments before and after pre-extrusion. It can be understood that the colloid has a certain rebound ability. Under the condition of applying the same external force, colloids with the same components and uniform mixing should have the same rebound ability, while uneven component distribution will lead to differences in local mechanical properties and changes in rebound ability, which will cause the abnormal rubber strip segments and normal rubber strip segments to exhibit different reactions when subjected to force and deformation. When the contours of the rubber strip segments before and after pre-extrusion differ, it indicates that the rebound ability of the rubber strip segments has changed and the component distribution of the rubber strip segments is uneven. The present invention screens out abnormal rubber strip segments with abnormal component enrichment in the colloid through the difference in contours of the rubber strip segments before and after pre-extrusion, thereby achieving rapid identification of abnormal mixing of modified starch powder with other adhesive making components, and improving the quality detection accuracy of the degradable hot melt adhesive and the stability of continuous preparation.

[0078] Specifically, the color changes of the feature points are determined as follows:

[0079] Obtaining the grayscale value of each feature point before instantaneous heating and the grayscale value of each feature point after instantaneous heating;

[0080] The absolute value of the difference between the grayscale value of the feature point before instantaneous heating and the grayscale value after instantaneous heating is calculated, and the absolute value of the difference is determined as the feature coefficient of the feature point.

[0081] Specifically, the grayscale value can be obtained by an industrial camera to obtain a clear image of the abnormal component-enriched rubber strip segment, and the grayscale value of the characteristic point can be calculated according to the brightness information of the pixels in the image by image analysis software, which will not be repeated here.

[0082] Specifically, when the present invention instantaneously heats the characteristic points, the heat will cause the modified starch around the characteristic points to migrate and gather toward the characteristic points. As the modified starch gathers at the characteristic points, the color changes at the characteristic points can accurately reflect the distribution density and dynamic migration characteristics of the modified starch around the characteristic points. By obtaining the color changes of each characteristic point, the distribution characteristics of the modified starch in the abnormal glue strip segment can be intuitively reflected, thereby achieving rapid identification of abnormal mixing of modified starch powder and other glue-making ingredients, thereby improving the quality detection accuracy of the degradable hot melt adhesive and the stability of continuous preparation.

[0083] Specifically, see Figure 3 As shown, it is a logic flow chart for determining the abnormal category of component enrichment of the adhesive strip according to an embodiment of the present invention. Determining the abnormal category of component enrichment of the adhesive strip includes:

[0084] If the characteristic coefficients of the characteristic points in each abnormal rubber strip segment on the colloid meet the component stratification enrichment condition, the component enrichment abnormal category of the colloid is determined to be the enrichment stratification abnormal category;

[0085] If the characteristic coefficients of the characteristic points in each abnormal colloid strip segment on the colloid do not meet the component stratification enrichment condition, the component enrichment abnormal category of the colloid is determined to be a non-enriched stratification abnormal category.

[0086] Specifically, the component stratification enrichment condition is that the difference between the characteristic coefficients of adjacent characteristic points does not exceed a preset characteristic coefficient threshold.

[0087] Specifically, the preset characteristic coefficient threshold may be determined by those skilled in the art based on experimental data from several experiments. Preferably, the characteristic coefficient threshold may be 25.

[0088] Specifically, the present invention determines the abnormal category of component enrichment of the colloid by the color change of each characteristic point. It can be understood that when the color change of each characteristic point is relatively consistent, the content and distribution of modified starch around the characteristic point are similar. When the color change of each characteristic point is quite different, the amount of modified starch moving to the characteristic point during the heating process is different. The characteristic point with more modified starch distributed around it has a more obvious color change after heating, while the color change of the characteristic point with less modified starch distributed around it is relatively weak, indicating that the content and distribution of modified starch around each point are different. Furthermore, the present invention determines the abnormal category of component enrichment of the colloid by the color change of each characteristic point after instantaneous heating, realizes the rapid identification of abnormal mixing of modified starch powder and other glue-making ingredients, judges the uniformity of the distribution of components inside the colloid, and improves the quality detection accuracy of the degradable hot melt adhesive and the stability of continuous preparation.

[0089] Specifically, see Figure 4 As shown, it is a logic flow chart of selecting an adjustment method for hot melt adhesive preparation and processing according to an embodiment of the present invention. The selected adjustment method for hot melt adhesive preparation and processing includes:

[0090] If the component enrichment abnormal category is the enrichment stratification abnormal category, then adjusting the duration of drying and dehydrating the modified starch according to the first image representation factor;

[0091] If the component enrichment abnormal category is the non-enrichment stratification abnormal category, the grinding time of the modified starch is adjusted according to the second image characterization factor.

[0092] Specifically, under the condition of enriched stratification abnormality category, the present invention adjusts the drying and dehydration time of the modified starch according to the first image characterization factor. It can be understood that in the preparation process of degradable hot melt adhesive, if the drying and dehydration time of the modified starch is insufficient, more water molecules will be retained in the starch granules. These water molecules will cause the modified starch to be poorly compatible with other components of the adhesive, resulting in internal component stratification caused by phase separation. By adjusting the drying and dehydration time of the modified starch, the moisture content in the modified starch can be reduced. Furthermore, the preparation and processing method of the hot melt adhesive is adaptively adjusted according to the mixing of the modified starch powder and other adhesive components, thereby improving the quality detection accuracy of the degradable hot melt adhesive and the stability of continuous preparation.

[0093] Specifically, the present invention adjusts the grinding time of the modified starch particles according to the second image characterization factor under the condition of non-enriched stratified abnormal category. It can be understood that under the condition of non-enriched stratified abnormal category, the uneven distribution of the modified starch in the characterization colloid is caused by the difference in the particle size of the modified starch. The difference in the particle size of the modified starch leads to a large difference in the color change of each characteristic point. By adjusting the grinding time of the modified starch particles, the particle size of the modified starch is made more uniform, thereby improving the quality detection accuracy of the degradable hot melt adhesive and the stability of continuous preparation.

[0094] Specifically, the average absolute value of the color change difference between adjacent feature points is determined as the first image characterization factor, and the sum of the maximum absolute value and the minimum absolute value of the color change difference of each feature point is determined as the second image characterization factor.

[0095] Specifically, the adjustment amount of the time for drying and dehydrating the modified starch is positively correlated with the first image representation factor, and the adjustment amount of the time for grinding the modified starch is positively correlated with the second image representation factor.

[0096] Specifically, the adjustment amount of the drying and dehydration time for the modified starch in the present invention is positively correlated with the first image characterization factor. It can be understood that by adjusting the drying and dehydration time, the drying degree of the modified starch can be optimized. The larger the first image characterization factor, the larger the average value of the color change difference of each characteristic point, which indicates that the modified starch contains more water. Appropriately extending the drying and dehydration time can remove excess water and make the modified starch more evenly distributed in the subsequent colloid stratification process, thereby improving the quality detection accuracy of the degradable hot melt adhesive and the stability of continuous preparation.

[0097] Specifically, the adjustment amount of the grinding time for the modified starch particles in the present invention is positively correlated with the second image characterization factor. It can be understood that the sum of the maximum and minimum values ​​of the color change difference of the characteristic points can overall reflect the degree of heterogeneity of the modified starch particles. When the second image characterization factor is large, it means that there are large differences in the particle size of the modified starch, and a longer grinding time is required to reduce the particle size difference of the modified starch, so that the modified starch is more evenly distributed, thereby improving the quality detection accuracy of the degradable hot melt adhesive and the stability of continuous preparation.

[0098] Specifically, a degradable hot melt adhesive includes the following components in parts by weight: 50 parts of modified starch and 33 to 49 parts of other adhesive-making ingredients;

[0099] Among them, other glue-making ingredients include 9-11 parts of ethylene glycol, 6-8 parts of acetyl triethyl citrate, 4-8 parts of triethyl citrate, 1-2 parts of antioxidant, 3-5 parts of complexing agent, and 10-15 parts of modified rosin.

[0100] Specifically, the antioxidant may be vitamin E, and the complexing agent may be manganese chloride.

[0101] In practice, the rosin can be heated to a molten state, and then glycerin and zinc oxide are added to react at 220-240° C. to obtain the modified rosin. This is prior art and will not be described in detail here.

[0102] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

[0103] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a degradable hot melt adhesive, characterized in that: include: Drying and dehydrating the gelatinized modified starch, and grinding the dried and dehydrated modified starch to obtain modified starch powder; Adding the modified starch powder and other adhesive-making ingredients into a reaction kettle, mixing and melting to prepare a hot melt adhesive colloid; Extruding the prepared hot melt adhesive colloid and dividing the extruded adhesive strip into a plurality of adhesive strip segments at preset intervals, pre-extrude each adhesive strip segment, determining the change of the adhesive strip segment contour according to the image of each adhesive strip segment before and after the pre-extruded image, and screening the adhesive strip segment with abnormal component enrichment based on the change of the adhesive strip segment contour; Determine a number of characteristic points at preset intervals for the abnormal rubber strip segment, instantaneously heat each characteristic point at a preset temperature value, and determine the abnormal category of component enrichment of the rubber strip according to the color change of each characteristic point; Based on the abnormal category of component enrichment, the adjustment method for the hot melt adhesive preparation process is selected, including: adjusting the duration of drying and dehydrating the modified starch according to the first image characterization factor; or, adjusting the grinding time of the modified starch according to the second image characterization factor; The first image characterization factor and the second image characterization factor are respectively determined based on the difference in color change of the feature point after instantaneous heating.

2. The method for preparing a degradable hot melt adhesive according to claim 1, characterized in that: Determine the difference in the profile of the rubber strip segment before and after pre-extrusion including: determining a contour image of the rubber strip segment before pre-extrusion as a first contour image, and calculating the first contour image area according to the first contour image; determining a contour image of the rubber strip segment after the pre-extrusion for a preset time as a second contour image, and calculating the area of ​​the second contour image according to the second contour image; The absolute value of the difference between the first contour image area and the second contour image area is determined as the contour difference amount of the rubber strip segment.

3. The method for preparing a degradable hot melt adhesive according to claim 2, characterized in that: The process of screening components to enrich abnormal strip segments includes: If the difference in the profile of the rubber strip segment before and after the pre-extrusion does not meet the normal component distribution condition, the rubber strip segment is screened as a rubber strip segment with abnormal component enrichment; The normal component distribution condition is that the contour difference does not exceed a preset contour difference threshold.

4. The method for preparing a degradable hot melt adhesive according to claim 3, characterized in that: Determine the color change of the feature points include: Obtaining the grayscale value of each feature point before instantaneous heating and the grayscale value of each feature point after instantaneous heating; The absolute value of the difference between the grayscale value of the feature point before instantaneous heating and the grayscale value after instantaneous heating is calculated, and the absolute value of the difference is determined as the feature coefficient of the feature point.

5. The method for preparing a degradable hot melt adhesive according to claim 4, characterized in that: Determine the abnormal category of component enrichment of the strip, including: If the characteristic coefficients of the characteristic points in each abnormal rubber strip segment on the colloid meet the component stratification enrichment condition, the component enrichment abnormal category of the colloid is determined to be the enrichment stratification abnormal category; If the characteristic coefficients of the characteristic points in each abnormal colloid strip segment on the colloid do not meet the component stratification enrichment condition, the component enrichment abnormal category of the colloid is determined to be a non-enriched stratification abnormal category.

6. The method for preparing a degradable hot melt adhesive according to claim 5, characterized in that: The component stratification enrichment condition is that the difference between the characteristic coefficients of adjacent characteristic points does not exceed a preset characteristic coefficient threshold.

7. The method for preparing a degradable hot melt adhesive according to claim 6, characterized in that: Selected adjustments to the hot melt adhesive preparation process include: If the component enrichment abnormal category is the enrichment stratification abnormal category, then adjusting the duration of drying and dehydrating the modified starch according to the first image representation factor; If the component enrichment abnormal category is the non-enrichment stratification abnormal category, the grinding time of the modified starch is adjusted according to the second image characterization factor.

8. The method for preparing a degradable hot melt adhesive according to claim 7, characterized in that: The average value of the absolute values ​​of the color change differences of adjacent feature points is determined as the first image characterization factor, and the sum of the maximum absolute value and the minimum absolute value of the color change differences of each feature point is determined as the second image characterization factor.

9. The method for preparing a degradable hot melt adhesive according to claim 7, characterized in that: The adjustment amount of the time for drying and dehydrating the modified starch is positively correlated with the first image representation factor, and the adjustment amount of the time for grinding the modified starch is positively correlated with the second image representation factor.

10. A degradable hot melt adhesive prepared by the method for preparing a degradable hot melt adhesive according to any one of claims 1 to 9, characterized in that: The invention comprises the following components in parts by weight: 50 parts of modified starch and 33 to 49 parts of other glue-making ingredients; Among them, other glue-making ingredients include 9-11 parts of ethylene glycol, 6-8 parts of acetyl triethyl citrate, 4-8 parts of triethyl citrate, 1-2 parts of antioxidant, 3-5 parts of complexing agent, and 10-15 parts of modified rosin.

Images