A degradable hot melt adhesive and preparation method thereof

Abstract

The present invention relates to the technical field of preparation of degradable hot melt adhesives, and in particular to a degradable hot melt adhesive and a preparation method thereof. The present invention prepares a hot melt adhesive colloid by adding modified starch powder and other adhesive-making ingredients into a reactor for mixing and melting, extruding the prepared hot melt adhesive colloid and dividing it into a plurality of adhesive strip segments, pre-extruded each adhesive strip segment, determining the contour change of the adhesive strip segment based on images of each adhesive strip segment before and after pre-extrusion to screen out adhesive strip segments with abnormal component enrichment, determining a plurality of characteristic points at preset intervals for the abnormal adhesive strip segment, instantaneously heating each characteristic point, determining the abnormal category of component enrichment of the adhesive strip based on the color change of each characteristic point, and selecting an adjustment method for the preparation and processing of the hot melt adhesive, thereby achieving adjustment of 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, and improving the quality detection accuracy and continuous preparation stability of the degradable hot melt adhesive.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of degradable hot melt adhesives, 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, whose main components are mostly non-degradable petroleum-based polymers, are difficult to decompose in the natural environment, causing serious "white pollution" problems. A large amount of waste hot melt adhesive products accumulate 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 come into being.

[0003] However, 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, rapid detection of the mixing of modified starch powder and other adhesive-making ingredients and improving the quality and stability of degradable hot melt adhesives are technical problems that need to be solved urgently.

[0004] For example, China Patent Authorization Announcement No.: CN116908051B, the invention discloses a method for testing 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 stage 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; testing the viscosity of 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 based on the temperature-viscosity curve and the standard temperature-viscosity curve.

[0005] The following problems also exist in the prior art:

[0006] The existing technology does not take into account that during the preparation of degradable hot melt adhesive, the difference in polarity between the modified starch and other adhesive ingredients causes poor melt mixing uniformity, which affects the fluidity of the hot melt adhesive. The existing technology cannot adaptively adjust the preparation and processing method of the hot melt adhesive according to the mixing conditions of the modified starch powder and other adhesive 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 of modified starch powder and other adhesive making ingredients, thereby 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 and dividing the extruded adhesive strip into a plurality of adhesive strip segments at preset intervals, pre-extruding each adhesive strip segment, determining an outline change of each adhesive strip segment based on images of each adhesive strip segment before and after pre-extrusion, and screening adhesive strip segments with abnormal component enrichment based on the outline change of the adhesive strip segment;

[0012] 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 based on the color change of each characteristic point;

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

[0014] adjusting the drying and dehydration time of 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 points after instantaneous heating.

[0017] Furthermore, the difference in the profile of the rubber strip segment before and after 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 based on the first contour image;

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

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

[0021] Furthermore, the process of screening for abnormal component enrichment of the strip segments includes:

[0022] If the difference in the profile of the rubber strip segment before and after 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] Furthermore, 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, then the component enrichment abnormality category of the colloid is determined to be the enrichment stratification abnormality 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 and enrichment conditions, the component enrichment abnormality category of the colloid is determined to be a non-enrichment stratification abnormality 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] Furthermore, the selected adjustment methods for the hot melt adhesive preparation process include:

[0032] If the component enrichment abnormality category is the enrichment stratification abnormality category, adjusting the drying and dehydration time of 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 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 to 11 parts of ethylene glycol, 6 to 8 parts of acetyl triethyl citrate, 4 to 8 parts of triethyl citrate, 1 to 2 parts of antioxidant, 3 to 5 parts of complexing agent, and 10 to 15 parts of modified rosin.

[0038] Compared with the prior art, the present invention has the following advantages: 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, and divides the extruded adhesive strip into a plurality of adhesive strip segments at preset intervals, pre-extrudes each adhesive strip segment, determines the change in the profile of each adhesive strip segment based on images of each adhesive strip segment before and after pre-extrusion, and screens the component enrichment based on the change in the profile of the adhesive strip segment. 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. Based on the abnormal category of component enrichment, the adjustment method for the preparation and processing of the hot melt adhesive is selected. 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 of the colloid through the difference in the 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 composition 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 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 of the colloid through the difference in the contours of the rubber strip segments before and after pre-extrusion, thereby realizing rapid identification of abnormal mixing of modified starch powder and other glue-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 realizing the 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 moved 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, thereby realizing rapid identification of abnormal mixing of modified starch powder and other glue-making ingredients, judging the uniformity of component distribution inside the colloid, and improving the quality detection accuracy of degradable hot melt adhesive and the stability of continuous preparation.

[0042] In particular, the present invention adjusts the drying and dehydration time of the modified starch according to the first image characterization factor under the condition of enrichment of stratification abnormality category. 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 the color changes 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.

[0044] In particular, the adjustment amount of the drying and dehydration time of 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 greater 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, so that the modified starch is 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 This is a step diagram of a method for preparing a degradable hot melt adhesive according to an embodiment of the present invention;

[0047] Figure 2 This is a logic flow chart for screening for abnormal component enrichment of a strip segment according to an embodiment of the present invention;

[0048] Figure 3 A logic flow chart for determining abnormal enrichment categories of components in 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 merely used to explain the present invention and are not intended 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 scope of protection 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 accompanying 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 and dividing the extruded adhesive strip into a plurality of adhesive strip segments at preset intervals, pre-extruding each adhesive strip segment, determining a change in the adhesive strip segment profile based on images of each adhesive strip segment before and after the pre-extrusion, and screening adhesive strip segments with abnormal component enrichment based on the change in the adhesive strip segment profile;

[0057] Specifically, the preset intervals for dividing the rubber strip segments may 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 may 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 based on the color change of each characteristic point;

[0060] Specifically, the preset interval distances for determining the 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 instantaneously 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 drying and dehydration time of 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 points after instantaneous heating.

[0066] Specifically, the differences in the profile of the rubber strip segment 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 based on the first contour image;

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

[0069] An absolute value of a difference between the first contour image area and the second contour image area is determined as a 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, the contour image of the rubber strip segment can be obtained by a camera, and then the edge algorithm can be used to extract the rubber strip contour in the contour image. The image processing software can be used to identify the pixel points in the image to obtain the first contour image area and the second contour image area. No further details will be given 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 for abnormal component-enriched rubber strip segments according to an embodiment of the present invention. The process of screening for abnormal component-enriched rubber strip segments includes:

[0073] If the difference in the profile of the rubber strip segment before and after 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 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 those 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 of the colloid through the difference in the 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 composition 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 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 of the colloid through the difference in the contours of the rubber strip segments before and after pre-extrusion, thereby realizing rapid identification of abnormal mixing of modified starch powder and other glue-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 enrichment strip segment, and the grayscale value of the feature point can be calculated based on the brightness information of the pixels in the image through 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 realizing the 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 in FIG, it is a logic flow chart for determining the abnormal category of component enrichment of a rubber strip according to an embodiment of the present invention. Determining the abnormal category of component enrichment of the rubber 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, then the component enrichment abnormality category of the colloid is determined to be the enrichment stratification abnormality 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 and enrichment conditions, the component enrichment abnormality category of the colloid is determined to be a non-enrichment stratification abnormality 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 can be determined by those skilled in the art based on experimental data from several experiments. Preferably, the characteristic coefficient threshold can 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 moved 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, thereby realizing rapid identification of abnormal mixing of modified starch powder and other glue-making ingredients, judging the uniformity of component distribution inside the colloid, and improving the quality detection accuracy of degradable hot melt adhesive and the stability of continuous preparation.

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

[0090] If the component enrichment abnormality category is the enrichment stratification abnormality category, adjusting the drying and dehydration time of 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, the present invention adjusts the drying and dehydration time of the modified starch according to the first image characterization factor under the condition of enrichment of stratification abnormality category. 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.

[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 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 the color changes 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 of 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 greater 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, so that the modified starch is 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 unevenness 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. 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 comprises 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 to 11 parts of ethylene glycol, 6 to 8 parts of acetyl triethyl citrate, 4 to 8 parts of triethyl citrate, 1 to 2 parts of antioxidant, 3 to 5 parts of complexing agent, and 10 to 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] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

[0103] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection 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 and dividing the extruded adhesive strip into a plurality of adhesive strip segments at preset intervals, pre-extruding each adhesive strip segment, determining an outline change of each adhesive strip segment based on images of each adhesive strip segment before and after pre-extrusion, and screening adhesive strip segments with abnormal component enrichment based on the outline change of the adhesive strip segment; 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 based on the color change of each characteristic point; Determining the color change of the characteristic points includes obtaining the grayscale value of each characteristic point before instantaneous heating and the grayscale value of each characteristic point after instantaneous heating, calculating the absolute value of the difference between the grayscale value of the characteristic point before instantaneous heating and the grayscale value after instantaneous heating, and determining the absolute value of the difference as the characteristic coefficient of the characteristic point; If the characteristic coefficients of the characteristic points in each abnormal rubber strip segment on the colloid meet the component stratification enrichment condition, then 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 do not meet the component stratification and enrichment conditions, the component enrichment abnormality category of the colloid is determined to be a non-enrichment stratification abnormality category; Based on the abnormal category of component enrichment, the adjustment method for hot melt adhesive preparation and processing is selected, including: If the component enrichment abnormality category is the enrichment stratification abnormality category, adjusting the drying and dehydration time of the modified starch according to the first image characterization factor; If the component enrichment abnormality category is the non-enrichment stratification abnormality category, adjusting the grinding time of the modified starch according to the second image characterization factor; Among them, the first image characterization factor and the second image characterization factor are respectively determined based on the difference in color change of the feature points after instantaneous heating, the average 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.

2. The method for preparing a degradable hot melt adhesive according to claim 1, wherein: 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 based on the first contour image; determining a contour image of the rubber strip segment after pre-extrusion for a preset time as a second contour image, and calculating an area of ​​the second contour image based on the second contour image; An absolute value of a difference between the first contour image area and the second contour image area is determined as a contour difference amount of the rubber strip segment.

3. The method for preparing a degradable hot melt adhesive according to claim 2, wherein: The process of screening for abnormally enriched strip segments includes: If the difference in the profile of the rubber strip segment before and after 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: 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.

5. The method for preparing a degradable hot melt adhesive according to claim 4, 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.

6. A degradable hot melt adhesive prepared by the method for preparing a degradable hot melt adhesive according to any one of claims 1 to 5, 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 adhesive-making ingredients; Among them, other glue-making ingredients include 9 to 11 parts of ethylene glycol, 6 to 8 parts of acetyl triethyl citrate, 4 to 8 parts of triethyl citrate, 1 to 2 parts of antioxidant, 3 to 5 parts of complexing agent, and 10 to 15 parts of modified rosin.

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