Recyclable, easy-to-rinse, low-density label and method for recycling same
Patent Information
- Application Number
- PCT/CN2025/140341
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-02-27
- Filing Date
- 2025-12-05
- Publication Date
- 2026-09-03
Smart Images
Figure PCTCN2025140341-FTAPPB-I100001 
Figure PCTCN2025140341-FTAPPB-I100002 
Figure PCTCN2025140341-FTAPPB-I100003
Abstract
Description
A recyclable, washable, low-density label and its recycling method
[0001] This application claims priority to Chinese Patent Application No. CN202510221310.4, filed on February 27, 2025, entitled "A Recyclable and Washable Low-Density Label and Its Recycling Method", the entire contents of which are incorporated herein by reference. Technical Field
[0002] This application relates to the field of shrink film processing technology, specifically to a recyclable, easy-to-wash, low-density label and its recycling method. Background Technology
[0003] Labels are commonly used in packaging materials for various foods and daily necessities, mainly as shrink sleeves, full-seal labels, bottle caps and bottle cap seals, etc. Compared with traditional label materials, label films have better adhesion, higher transparency, and better visibility of the packaged goods; at the same time, they also have better strength and wear resistance, and have been widely used in various fields in recent years.
[0004] Label films typically use heat shrink film as the main material. Heat shrink film has good gloss, adhesion and shrinkage properties. Due to the gloss and shrinkage of heat shrink film, the packaging pattern on the container is more vivid and can better stand out on the supermarket shelf, creating an unexpected shelf effect, and is therefore widely used for container packaging.
[0005] The main materials used for heat shrink film in labeling include polyvinyl chloride (PVC), polyethylene terephthalate-1,4-cyclohexanediol (PETG), and oriented polystyrene (OPS). PVC heat shrink film has characteristics such as high tensile strength, high elongation, good self-adhesion, and high transparency, but it also has the drawback of easily generating highly toxic dioxins during recycling and poor environmental performance, leading to its gradual ban. OPS heat shrink film has characteristics such as high strength, high rigidity, shape stability, good gloss and transparency, and is easy to process, easy to color, has good printability, and extremely high printing resolution, while also being inexpensive. PETG heat shrink film is non-toxic, odorless, high-strength, high heat shrinkage rate, good optical properties, mechanical elongation, and aesthetically pleasing packaging effects, resulting in the rapid growth in the use of OPS and PETG heat shrink films.
[0006] However, both PVC heat shrink film and OPS heat shrink film have the problem of high density. In the subsequent recycling process, when containers with a density greater than water, such as polyethylene terephthalate (PET) bottles, and PETG or OPS heat shrink film are cut into pieces for flotation, the container materials with a density greater than water, such as PET bottles, and PETG or OPS heat shrink film will sink in the water because the flotation medium is water. This makes it difficult to separate the container materials with a density greater than water, such as PET bottles, from PETG and / or OPS heat shrink film. If PETG and / or OPS heat shrink film are introduced into the container materials with a density greater than water, such as PET bottles, during the recycling process, the quality of the container materials will be weakened, making the recycled container materials unusable in the bottle blowing process, thus affecting the recycling of container materials with a density greater than water, such as PET bottles.
[0007] Meanwhile, the adhesion and stability of ink on labels in existing technologies still need to be improved. The ink printed on them cannot be maintained for a long time in humid environments, and cannot be washed off quickly and cleanly during the recycling process, which affects the quality of recycled materials.
[0008] Therefore, there is an urgent need for a low-density label that can improve ink adhesion and achieve impurity-free recovery after flotation and rinsing. Summary of the Invention
[0009] In order to overcome the problems existing in the prior art, this application provides a recyclable, easy-to-wash, low-density label and its recycling method that can improve ink adhesion and achieve impurity-free recovery after flotation and rinsing.
[0010] This application provides a recyclable and washable low-density label, which is prepared by surface modification of a low-density heat-shrinkable film with a surface modifier.
[0011] The density of the low-density heat-shrinkable film is less than 0.96 g / cm³. 3 ;
[0012] The surface modifier is prepared by reacting tetraethyl orthosilicate, N-(2-N-benzylaminoethyl)-3-aminopropyltrimethoxysilane and acetoxyethyltrimethoxysilane via a sol-gel method.
[0013] This application achieves this by controlling the density of the heat-shrinkable film to be less than 0.96 g / cm³. 3 This allows it to float on the surface of water after being crushed, and be separated from other components by flotation due to density differences. The separation process is simple and efficient, and is suitable for large-scale recycling programs.
[0014] Furthermore, the surface modifier is prepared through the following steps:
[0015] (1) Add tetraethyl orthosilicate, p-toluenesulfonic acid and anhydrous ethanol to the reactor and stir until homogeneous to form solution a;
[0016] (2) In the reactor, N-(2-N-benzylaminoethyl)-3-aminopropyltrimethoxysilane, acetoxyethyltrimethoxysilane and anhydrous ethanol are added and stirred until homogeneous to form solution b;
[0017] (3) In the reactor, add solution a and solution b, heat to 40-50℃ and stir for 4-6 hours, then cool to obtain the surface modifier.
[0018] The surface modifier in this application has two advantages. First, its sol-gel form has a uniform size, which can be uniformly grafted onto the surface of the pretreated heat shrink film, improving the smoothness of the heat shrink film surface. This allows inks with uniform particle size to fully fill the surface of the heat shrink film, preventing air and other components from occupying it, thereby increasing the adhesion area of the ink and improving the adhesion effect. Second, its polyamino and benzene ring structure can form a stable network structure on the surface of the heat shrink film, which can not only prevent moisture intrusion in humid environments, but also improve the lightfastness of the ink. At the same time, its network structure can be rapidly decomposed under the influence of water-based rinsing solution, achieving rapid rinsing of the ink.
[0019] Furthermore, the mass ratio of tetraethyl orthosilicate, p-toluenesulfonic acid, and anhydrous ethanol in solution a is (15-20):(1-2):(35-50).
[0020] Further, the mass ratio of N-(2-N-benzylaminoethyl)-3-aminopropyltrimethoxysilane, acetoxyethyltrimethoxysilane and anhydrous ethanol in solution b is (10-12):(6-8):(35-50).
[0021] Furthermore, in step (3), the mass ratio of solution a to solution b is (6-8):(4-5).
[0022] Furthermore, the recyclable, washable, low-density label is prepared through the following steps:
[0023] (1) Add potassium permanganate and deionized water to the reactor, stir evenly, then slowly add concentrated sulfuric acid, heat to 35-40℃, then add low-density heat shrink film, stir and react for 10-15 minutes, then remove the low-density heat shrink film, wash and complete the pretreatment.
[0024] (2) The pretreated low-density heat shrink film is immersed in a surface modifier, stirred and reacted for 30-45 minutes, and then washed and dried to obtain the recyclable and easy-to-wash low-density label.
[0025] This application uses potassium permanganate and concentrated sulfuric acid to perform oxidative pretreatment on the label material, which not only allows the surface modifier to be effectively grafted onto the surface of the heat shrink film, but also modifies the uniformity of its surface, so that the surface modifier is uniformly attached to the surface of the heat shrink film.
[0026] Further, in step (1), the mass fraction of concentrated sulfuric acid is 90-98 wt%; the mass ratio of potassium permanganate, concentrated sulfuric acid and deionized water is (5-8):(1-2):(80-90).
[0027] The recycling method for any of the above recyclable, washable, low-density labels includes the following steps:
[0028] (1) Crushing: Crushing bottles containing recyclable, washable, low-density labels;
[0029] (2) Flotation: The crushed material is placed in an aqueous solution containing surfactant, and after stirring and shaking, the recyclable and washable low-density label floats on the water surface.
[0030] (3) Rinsing: Transfer the recyclable and easy-to-rinse low-density labels to the rinsing solution, heat to 35-40℃ and stir for 15-20 minutes, then filter, wash and dry to achieve the recycling of recyclable and easy-to-rinse low-density labels.
[0031] Further, in step (2), the surfactant is selected from one of ethylenedimethylammonium chloride (dodecyl dimethyl ammonium chloride), propylenedimethylammonium chloride (hexadecyl dimethyl ammonium bromide), or ethylenedimethylammonium chloride (octadecyl dimethyl ammonium chloride); the amount of surfactant added is 0.3-1 wt% of the water mass.
[0032] This application improves the flotation recovery effect of labels by adding surfactants to the water during the flotation process, which can disrupt the surface tension between the components and the water, reduce the situation where high-density materials float on the water surface due to attached bubbles or surface tension.
[0033] Furthermore, the rinsing solution in step (3) is prepared by mixing ethyl acetate, pentaerythritol, cocamidopropyl betaine, triethanolamine and deionized water.
[0034] The beneficial effects of this application are:
[0035] (1) The recyclable and washable low-density label provided in this application is made by surface modification of low-density heat shrink film with surface modifier. The surface-modified label can not only improve the adhesion and stability of ink on its surface, but also make it quick to separate through simple flotation during recycling. Furthermore, the ink on the label can be effectively washed in the rinsing solution, improving the rinsing effect of the ink, thereby achieving the recycling of the label without impurities.
[0036] (2) The recyclable, washable, low-density label provided in this application controls the density of the heat-shrinkable film to be less than 0.96 g / cm³. 3 This allows it to float on the surface of water after being crushed, and be separated from other components by flotation due to density differences. The separation process is simple and efficient, and is suitable for large-scale recycling programs.
[0037] (3) The recycling method for recyclable and easy-to-wash low-density labels provided in this application can break the surface tension between each component and water by adding surfactants to the water during the flotation process, thereby reducing the situation where high-density materials float on the water surface due to attached bubbles or surface tension, and thus improving the flotation recycling effect of the labels.
[0038] (4) The recyclable and washable low-density label provided in this application is prepared by sol-gel method using tetraethyl orthosilicate, N-(2-N-benzylaminoethyl)-3-aminopropyltrimethoxysilane and acetoxyethyltrimethoxysilane to obtain a surface modifier. On the one hand, its sol-gel form has a uniform size, which can be uniformly grafted onto the surface of the pretreated heat shrink film, which can improve the smoothness of the heat shrink film surface, so that ink with uniform particle size can be fully filled on the surface of the heat shrink film, avoiding the occupation of air and other components, thereby increasing the adhesion area of the ink and improving the adhesion effect. On the other hand, its polyamino and benzene ring structure can form a stable network structure on the surface of the heat shrink film, which can not only avoid the intrusion of moisture in the humid environment, but also improve the lightfastness of the ink. At the same time, its network structure can be rapidly decomposed under the influence of water-based rinsing solution, realizing rapid rinsing of ink.
[0039] (5) The recyclable and washable low-density label provided in this application uses potassium permanganate and concentrated sulfuric acid to pre-oxidize the label material, which not only allows the surface modifier to be effectively grafted onto the surface of the heat shrink film, but also modifies the uniformity of its surface, so that the surface modifier is uniformly attached to the surface of the heat shrink film. Detailed Implementation
[0040] The present application will be described below with reference to specific implementation schemes. It should be noted that the following embodiments are examples of the present application and are only used to illustrate the present application, and are not intended to limit the present application. Other combinations and various modifications within the scope of the present application can be made without departing from the spirit or scope of the present application.
[0041] The CAS number of N-(2-N-benzylaminoethyl)-3-aminopropyltrimethoxysilane is 209866-89-7; the low-density heat-shrinkable film was prepared according to the method of patent CN202311725243.7; the commercially available silica sol was purchased from Yuanyang County Lutong Refractory Materials Co., Ltd. as JN-30; the commercially available rinsing solution was purchased from Changzhou Aozun Composite New Materials Co., Ltd. as No. 120 solvent oil; the remaining reagents and equipment are conventional reagents and equipment in this technical field.
[0042] Preparation of Surface Modifier-1
[0043] Surface modifier-1 was prepared by the following steps: by weight parts,
[0044] (1) In the reactor, add 1.5 parts of tetraethyl orthosilicate, 0.1 parts of p-toluenesulfonic acid and 5 parts of anhydrous ethanol, and stir until homogeneous to form solution a;
[0045] (2) In the reactor, add 1 part of N-(2-N-benzylaminoethyl)-3-aminopropyltrimethoxysilane, 0.8 parts of acetoxyethyltrimethoxysilane and 5 parts of anhydrous ethanol, and stir until homogeneous to form solution b;
[0046] (3) Add 8 parts of solution a and 5 parts of solution b to the reactor, heat to 50°C and stir for 4 hours, then cool to obtain the surface modifier-1.
[0047] Preparation of Surface Modifier-2
[0048] The preparation is basically the same as that of surface modifier-1, except that N-(2-N-benzylaminoethyl)-3-aminopropyltrimethoxysilane is replaced with an equal amount of acetoxyethyltrimethoxysilane.
[0049] Example 1
[0050] Recyclable, washable, low-density labels are prepared by the following steps: by weight parts
[0051] (1) In the reactor, add 0.5 parts of potassium permanganate and 9 parts of deionized water, stir evenly, and slowly add 0.2 parts of concentrated sulfuric acid with a mass fraction of 98wt%. Heat to 40°C and add low-density heat shrink film. Stir and react for 15 minutes, then remove the low-density heat shrink film, wash and complete the pretreatment.
[0052] (2) The pretreated low-density heat shrink film is immersed in surface modifier-1, stirred and reacted for 30 minutes, and then washed and dried to obtain the recyclable and easy-to-wash low-density label.
[0053] The density of the low-density heat-shrinkable film is 0.93 g / cm³. 3 ;
[0054] The following steps are used to recycle recyclable, washable, low-density labels:
[0055] (1) Crushing: Crushing bottles containing recyclable, washable, low-density labels;
[0056] (2) Flotation: The crushed material is placed in an aqueous solution containing 0.5 wt% ethylene bis(dodecyl dimethyl ammonium chloride), and after stirring and shaking, the recyclable and washable low-density label floats on the water surface;
[0057] (3) Rinsing: Transfer the recyclable and easy-to-rinse low-density labels to the rinsing solution, heat to 35°C and stir for 20 minutes, then filter, wash and dry to achieve the recycling of recyclable and easy-to-rinse low-density labels;
[0058] The rinsing solution was prepared by mixing 10 wt% ethyl acetate, 5 wt% pentaerythritol, 1.5 wt% cocamidopropyl betaine, 3.5 wt% triethanolamine and 80 wt% deionized water.
[0059] Example 2
[0060] The method is basically the same as in Example 1, except that the density of the low-density heat shrink film is 0.95 g / cm³. 3 During the flotation process, ethylenedimethylammonium chloride (EDMC) was replaced with an equal amount of propylenedimethylammonium bromide (CDI).
[0061] Example 3
[0062] The method is basically the same as in Example 1, except that the density of the low-density heat shrink film is 0.92 g / cm³. 3 During the flotation process, ethylenedimethylammonium chloride (EDMC) was replaced with an equal amount of ethylenedimethylammonium chloride (EDMC).
[0063] Comparative Example 1
[0064] The recycling steps are basically the same as in Example 1, except that the recyclable and washable low-density labels are not prepared, and instead, PET heat-shrinkable film is used instead.
[0065] Comparative Example 2
[0066] The process is basically the same as in Example 1, except that the surface modifier-1 in the preparation of the recyclable and washable low-density label is replaced with an equal amount of commercially available silica sol.
[0067] Comparative Example 3
[0068] The process is basically the same as in Example 1, except that surface modifier-1 is replaced with an equal amount of surface modifier-2 in the preparation of the recyclable, easy-to-wash, low-density label.
[0069] Comparative Example 4
[0070] The process is basically the same as in Example 1, except that ethylene bis(dodecyl dimethyl ammonium chloride) is not added in the recovery step (2).
[0071] Comparative Example 5
[0072] The process is basically the same as in Example 1, except that the rinsing solution in the recovery step (3) is replaced with an equal amount of commercially available rinsing solution.
[0073] Performance testing
[0074] Ink adhesion test: According to the test method of GB / T 9286-2021 Cross-cut test for paints and varnishes, the PET heat shrink films in Examples 1-3 and Comparative Example 1, as well as the label films in Comparative Examples 2-3, were printed with conventional water-based inks, and the ink adhesion grade-1 was tested.
[0075] Moisture and heat resistance test: The PET heat shrink film of Examples 1-3 and Comparative Example 1 and the label film of Comparative Examples 2-3 were placed in an environment with a temperature of 45°C and a relative humidity of 98% for 144 hours and then their adhesion level-2 was tested again according to GB / T 9286-2021.
[0076] Lightfastness testing: The PET heat-shrinkable films from Examples 1-3 and Comparative Example 1, as well as the label films from Comparative Examples 2-3, were placed under an irradiation wavelength of 420 nm, a temperature of 40 °C, and an irradiation intensity of 1.5 W / m². 2 After being left to stand in the environment for 36 hours, its adhesion rating was tested again according to GB / T 9286-2021, and the rating was -3.
[0077] The test results are shown in the table below:
[0078] According to the comparison of the test results of Examples 1-3 and Comparative Example 1, the recyclable and washable low-density label provided in this application has excellent adhesion to ink compared with the label material in the prior art, and can improve the ink's resistance to damp heat and light, and improve the effect and stability of ink printing.
[0079] The test results of Examples 1-3 and Comparative Examples 2-3 show that the recyclable and washable low-density labels provided in this application, after being modified with surface modifiers, can significantly improve the adhesion and stability of inks and extend their service life.
[0080] Recycling effect test: The flotation rate and the content of impurities, including ink, of the labels in Examples 1-3 and Comparative Examples 1-5 were tested and recorded respectively. The flotation rate test method is as follows: Take 1000 labeled bottles, calculate the total weight of the labels (referred to as W1), clean the bottles using a bottle fragment recycling system, and crush and float them according to the method in the example or comparative example, collect the bottle fragments, screen and collect the labels that have not been separated and weigh them (referred to as W2), and then calculate the flotation rate according to the formula "flotation rate (%) = 1 - W2 / W1". The impurity content detection method is as follows: Randomly select 10 full-page printed sample label blocks of 10×10cm, rinse them according to the method in the example or comparative example, place them on graph paper (squares 1×1mm), read the number of squares with ink (squares with an area containing ink exceeding 50% are counted as one square, and squares with less than 50% are not counted), and record it as N1. The impurity content of each sample is N1 / 100, and the average impurity content of 10 samples is taken as the impurity content.
[0081] The test results are shown in the table below:
[0082] According to the comparison of the inspection results of Examples 1-3 and Comparative Example 1, the recyclable and easy-to-wash low-density label and its recycling method provided in this application have better flotation and rinsing effects than the label materials in the prior art, and can effectively recycle the label materials without impurities, thus providing their application value.
[0083] According to the comparison of the test results of Examples 1-3 and Comparative Examples 2-3, the recyclable and washable low-density labels and their recycling method provided in this application can improve the rinsing effect of the rinsing solution on the ink and reduce the impurity content by modifying the label material with a surface modifier.
[0084] According to the comparison of the test results of Examples 1-3 and Comparative Examples 4-5, the recyclable and easy-to-wash low-density labels and their recycling method provided in this application can improve the flotation and rinsing effects of the labels by adding surfactants during the flotation process and using rinsing solutions with specific components during the rinsing process.
[0085] The above embodiments are only for illustrating the technical concept and features of this application. Their purpose is to enable those skilled in the art to understand the content of this application and implement it. They should not be used to limit the scope of protection of this application. All equivalent changes or modifications made in accordance with the spirit and essence of this application should be included within the scope of protection of this application.
Claims
1. A recyclable, washable, low-density label, characterized in that, The recyclable and washable low-density label is prepared by surface modification of a low-density heat-shrinkable film using a surface modifier. The density of the low-density heat-shrinkable film is less than 0.96 g / cm³. 3 ; The surface modifier is prepared by reacting tetraethyl orthosilicate, N-(2-N-benzylaminoethyl)-3-aminopropyltrimethoxysilane and acetoxyethyltrimethoxysilane via a sol-gel method.
2. The recyclable, washable, low-density label according to claim 1, characterized in that, The surface modifier is prepared by the following steps: (1) Add tetraethyl orthosilicate, p-toluenesulfonic acid and anhydrous ethanol to the reactor and stir until homogeneous to form solution a; (2) In the reactor, N-(2-N-benzylaminoethyl)-3-aminopropyltrimethoxysilane, acetoxyethyltrimethoxysilane and anhydrous ethanol are added and stirred until homogeneous to form solution b; (3) In the reactor, add solution a and solution b, heat to 40-50℃ and stir for 4-6 hours, then cool to obtain the surface modifier.
3. The recyclable, washable, low-density label according to claim 2, characterized in that, The mass ratio of tetraethyl orthosilicate, p-toluenesulfonic acid and anhydrous ethanol in solution a is (15-20):(1-2):(35-50).
4. The recyclable, washable, low-density label according to claim 2, characterized in that, The mass ratio of N-(2-N-benzylaminoethyl)-3-aminopropyltrimethoxysilane, acetoxyethyltrimethoxysilane and anhydrous ethanol in solution b is (10-12):(6-8):(35-50).
5. The recyclable, washable, low-density label according to claim 2, characterized in that, In step (3), the mass ratio of solution a to solution b is (6-8):(4-5).
6. The recyclable, washable, low-density label according to claim 1, characterized in that, The recyclable, washable, low-density label is prepared through the following steps: (1) Add potassium permanganate and deionized water to the reactor, stir evenly, then slowly add concentrated sulfuric acid, heat to 35-40℃, then add low-density heat shrink film, stir and react for 10-15 minutes, then remove the low-density heat shrink film, wash and complete the pretreatment. (2) The pretreated low-density heat shrink film is immersed in a surface modifier, stirred and reacted for 30-45 minutes, and then washed and dried to obtain the recyclable and easy-to-wash low-density label.
7. The recyclable, washable, low-density label according to claim 6, characterized in that, In step (1), the mass fraction of concentrated sulfuric acid is 90-98 wt%; the mass ratio of potassium permanganate, concentrated sulfuric acid and deionized water is (5-8):(1-2):(80-90).
8. The recycling method for recyclable, washable, low-density labels according to any one of claims 1-7, characterized in that, Includes the following steps: (1) Crushing: Crushing the bottles containing recyclable, washable, low-density labels; (2) Flotation: The crushed material is placed in an aqueous solution containing surfactant, and after stirring and shaking, the recyclable and washable low-density label floats on the water surface. (3) Rinsing: Transfer the recyclable and easy-to-rinse low-density labels to the rinsing solution, heat to 35-40℃ and stir for 15-20 minutes, then filter, wash and dry to achieve the recycling of recyclable and easy-to-rinse low-density labels.
9. The recycling method for recyclable, washable, low-density labels according to claim 8, characterized in that, In step (2), the surfactant is selected from one of ethylenedimethylammonium chloride (dodecyl dimethyl ammonium chloride), propylenedimethylammonium chloride (hexadecyl dimethyl ammonium bromide), or ethylenedimethylammonium chloride (octadecyl dimethyl ammonium chloride); the amount of surfactant added is 0.3-1 wt% of the water mass.
10. The recycling method for recyclable, washable, low-density labels according to claim 8, characterized in that, The rinsing solution in step (3) is prepared by mixing ethyl acetate, pentaerythritol, cocamidopropyl betaine, triethanolamine and deionized water.