Recyclable easy-to-rinse low-density label and recycling method thereof

Abstract

The present invention discloses a recyclable, easy-to-rinse low-density label and a recycling method thereof. The recyclable, easy-to-rinse low-density label is prepared by surface-modifying a low-density heat shrink film with a surface modifier; the density of the low-density heat shrink film is less than 0.96g / cm3; the surface modifier is prepared by reacting ethyl orthosilicate, N-(2-N-benzylaminoethyl)-3-aminopropyltrimethoxysilane, and acetoxyethyltrimethoxysilane through a sol-gel process. The surface-modified label of the present invention can not only improve the adhesion and stability of the ink on its surface, but also can achieve rapid separation through simple flotation during the recycling process, and can effectively rinse the ink on the label in a rinsing solution, thereby improving the rinsing effect of the ink and achieving impurity-free recycling of the label.

Description

Technical Field

[0001] The invention relates to the technical field of shrink film processing technology, and in particular to a recyclable, easy-to-rinse low-density label and a recycling method thereof. Background Art

[0002] Labels are commonly used as packaging materials for various foods and daily necessities, mainly used as shrink sleeves, full-seal labels, bottle caps and bottle cover seals, etc. Compared with traditional label materials, label films have better adhesion, higher transparency, and better visualization of packaging; at the same time, they also have good strength and wear resistance. In recent years, they have been widely used in various fields.

[0003] Label film usually uses heat shrink film as the main material. Heat shrink film has good gloss, fit and shrinkage properties. The gloss and shrinkage of heat shrink film make the packaging pattern on the container more vivid, more prominent on the supermarket shelves, and produce an unexpected container effect, and is widely used in container packaging.

[0004] Existing heat shrink film materials for labels primarily include polyvinyl chloride (PVC), polyethylene terephthalate (PETG), and oriented polystyrene (OPS). PVC heat shrink film boasts high tensile strength, high elongation, good self-adhesion, and high transparency. However, it also suffers from the environmental concerns of generating highly toxic dioxins during recycling, leading to its gradual ban. OPS heat shrink film offers high strength, rigidity, stable form, good gloss, and transparency, as well as ease of processing, coloring, excellent printability, and high resolution, all at a low price. PETG heat shrink film, while non-toxic, odorless, high strength, high heat shrinkage, excellent optical properties, mechanical extensibility, and aesthetically pleasing packaging, has led to a rapid increase in the use of both OPS and PETG heat shrink films.

[0005] However, both PVC heat shrink film and OPS heat shrink film have the problem of high density. In the subsequent recycling process, when polyethylene terephthalate (PET) bottles and other containers with a density greater than water and PETG heat shrink film or OPS heat shrink film are cut into pieces for flotation, since the flotation medium is water, PET bottles and other container materials with a density greater than water and PETG heat shrink film or OPS heat shrink film will all sink into the water, making it difficult to separate PET bottles and other container materials with a density greater than water from PETG heat shrink film and / or OPS heat shrink film. If PETG heat shrink film and / or OPS heat shrink film material is introduced into PET bottles and other container materials with a density greater than water during the recycling process, the quality of the container material will be weakened, and the recycled container material will no longer be able to be used in the bottle blowing process, thereby affecting the recycling of PET bottles and other container materials with a density greater than water.

[0006] At the same time, the adhesion effect and stability of ink on labels in the existing technology still need to be improved. The printed ink cannot be maintained for a long time in humid environments, and cannot be washed off quickly and cleanly during the recycling process, affecting the quality of the recycled materials.

[0007] Therefore, there is an urgent need for a low-density label that can improve ink adhesion and can be recovered without impurities after flotation and rinsing. Summary of the Invention

[0008] In order to overcome the problems existing in the prior art, the present invention provides a recyclable, easy-to-rinse low-density label and a recycling method thereof, which can improve the ink adhesion effect and can be recovered without impurities after flotation and rinsing.

[0009] The present invention provides a recyclable, easy-to-rinse, low-density label, which is prepared by surface-modifying a low-density heat shrinkable film with a surface modifier.

[0010] The density of the low-density heat shrinkable film is less than 0.96 g / cm 3 ;

[0011] The surface modifier is prepared by reacting ethyl orthosilicate, N-(2-N-benzylaminoethyl)-3-aminopropyltrimethoxysilane and acetoxyethyltrimethoxysilane through a sol-gel method.

[0012] The present invention controls the density of the heat shrinkable film to be less than 0.96 g / cm 3 , so that it can float on the surface of the water after being crushed, and can be separated from other components by flotation due to the density difference. The separation process is simple and efficient, and is suitable for large-scale recovery procedures.

[0013] Furthermore, the surface modifier is prepared by the following steps:

[0014] (1) Add ethyl orthosilicate, p-toluenesulfonic acid and anhydrous ethanol into a reactor and stir to form solution a;

[0015] (2) Add N-(2-N-benzylaminoethyl)-3-aminopropyltrimethoxysilane, acetoxyethyltrimethoxysilane and anhydrous ethanol into the reactor and stir to form solution b;

[0016] (3) Add solution a and solution b into a reactor, heat to 40-50°C, stir and react for 4-6 hours, and then cool to obtain the surface modifier.

[0017] The surface modifier of the present invention has, on the one hand, a uniform size in the form of a sol-gel and can be evenly grafted onto the surface of a pretreated heat-shrinkable film, thereby improving the flatness of the heat-shrinkable film surface and allowing ink with a uniform particle size to be fully filled onto the heat-shrinkable film surface, thereby preventing air and other components from occupying the surface. This increases the ink adhesion area and improves the adhesion effect. On the other hand, the structure of the polyamino group and benzene ring can form a stable network structure on the surface of the heat-shrinkable film, which not only prevents the intrusion of water in a humid environment but also improves the light resistance of the ink. At the same time, the network structure can be rapidly decomposed under the influence of a water-based rinsing liquid, thereby achieving rapid rinsing of the ink.

[0018] Furthermore, the mass ratio of ethyl orthosilicate, p-toluenesulfonic acid and anhydrous ethanol in the solution a is (15-20): (1-2): (35-50).

[0019] Furthermore, the mass ratio of N-(2-N-benzylaminoethyl)-3-aminopropyltrimethoxysilane, acetoxyethyltrimethoxysilane and anhydrous ethanol in the solution b is (10-12): (6-8): (35-50).

[0020] Furthermore, in step (3), the mass ratio of solution a to solution b is (6-8):(4-5).

[0021] Furthermore, the recyclable easy-to-rinse low-density label is prepared by the following steps:

[0022] (1) Add potassium permanganate and deionized water to the reactor, stir evenly and then slowly add concentrated sulfuric acid. Heat to 35-40°C and then add low-density heat shrink film. Stir and react for 10-15 minutes, then take out the low-density heat shrink film and wash it to complete the pretreatment.

[0023] (2) The pretreated low-density heat shrinkable film is immersed in a surface modifier, stirred for reaction for 30-45 minutes, and then washed and dried to obtain the recyclable and easy-to-rinse low-density label.

[0024] The present invention performs oxidation pretreatment on the label material by using potassium permanganate and concentrated sulfuric acid, which not only enables the surface modifier to be effectively grafted on the surface of the heat shrinkable film, but also modifies the uniformity of the surface, so that the surface modifier is evenly attached to the surface of the heat shrinkable film.

[0025] Furthermore, the mass fraction of concentrated sulfuric acid in step (1) is 90-98 wt %; and the mass ratio of potassium permanganate, concentrated sulfuric acid and deionized water is (5-8): (1-2): (80-90).

[0026] Any of the above methods for recycling recyclable easy-rinsable low-density labels, comprising the following steps:

[0027] (1) Crushing: Crushing the bottle with recyclable, easy-to-rinse, low-density label;

[0028] (2) Flotation: The crushed material is placed in an aqueous solution containing a surfactant, and after stirring and shaking, the recyclable, easy-to-rinse, low-density label floats on the water surface;

[0029] (3) Rinsing: Transfer the recyclable easy-rinsing low-density labels into the rinsing liquid, heat it to 35-40°C and stir it for 15-20 minutes, then filter, wash and dry it to achieve the recycling of the recyclable easy-rinsing low-density labels.

[0030] Furthermore, in step (2), the surfactant is selected from one of ethylene bis(dodecyldimethylammonium chloride), propylene bis(hexadecyldimethylammonium bromide) or ethylene bis(octadecyldimethylammonium chloride); and the amount of the surfactant added is 0.3-1 wt% of the mass of water.

[0031] The present invention adds a surfactant to water during the flotation process, thereby destroying the surface tension between each component and water, reducing the situation where materials with higher density float on the water surface due to attached bubbles or surface tension, and thus improving the flotation recovery effect of the label.

[0032] Furthermore, the rinsing liquid in step (3) is prepared by mixing ethyl acetate, pentaerythritol, cocamidopropyl betaine, triethanolamine and deionized water.

[0033] Beneficial effects of the present invention:

[0034] (1) The recyclable, easy-to-rinse low-density label provided by the present invention is obtained by surface-modifying a low-density heat shrinkable film with a surface modifier. The surface-modified label can not only improve the adhesion and stability of the ink on its surface, but also can be quickly separated by simple flotation during the recycling process, and the ink on the label can be effectively rinsed in the rinsing liquid, thereby improving the rinsing effect of the ink and realizing the impurity-free recycling of the label.

[0035] (2) The recyclable, easy-to-rinse, low-density label provided by the present invention is obtained by controlling the density of the heat shrinkable film to be less than 0.96 g / cm 3 , so that it can float on the surface of the water after being crushed, and can be separated from other components by flotation due to the density difference. The separation process is simple and efficient, and is suitable for large-scale recovery procedures.

[0036] (3) The present invention provides a method for recovering recyclable, easy-to-rinse, low-density labels. By adding a surfactant to water during the flotation process, the surface tension between each component and water can be destroyed, thereby reducing the situation where materials with higher density float on the water surface due to attached bubbles or surface tension, thereby improving the flotation recovery effect of the labels.

[0037] (4) The recyclable, easy-to-rinse low-density label provided by the present invention is prepared by a sol-gel method using ethyl orthosilicate, N-(2-N-benzylaminoethyl)-3-aminopropyltrimethoxysilane and acetoxyethyltrimethoxysilane to obtain a surface modifier. On the one hand, the sol-gel form has a uniform size and can be evenly grafted on the surface of the pretreated heat shrink film, which can improve the flatness of the heat shrink film surface and enable ink with a uniform particle size to be fully filled on the heat shrink film surface, avoiding the occupation of components such as air, thereby increasing the adhesion area of ​​the ink and improving the adhesion effect; on the other hand, the structure of the polyamino group and benzene ring can form a stable network structure on the surface of the heat shrink film, which can not only avoid the intrusion of water in a humid environment, but also improve the light resistance of the ink. At the same time, the network structure can be quickly decomposed under the influence of a water-based rinse solution, thereby achieving rapid rinsing of the ink.

[0038] (5) The recyclable, easy-to-rinse, low-density label provided by the present invention is oxidized by pre-treating the label material with potassium permanganate and concentrated sulfuric acid, which not only allows the surface modifier to be effectively grafted onto the surface of the heat shrinkable film, but also modifies the uniformity of the surface, so that the surface modifier is evenly attached to the surface of the heat shrinkable film. DETAILED DESCRIPTION

[0039] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following examples are illustrative of the present invention and are intended only to illustrate the present invention and are not intended to limit the present invention. Other combinations and various modifications within the scope of the present invention may be made without departing from the spirit or scope of the present invention.

[0040] The CAS number of N-(2-N-benzylaminoethyl)-3-aminopropyltrimethoxysilane is 209866-89-7; the low-density heat shrinkable film is prepared according to the method of patent CN202311725243.7; the commercially available silica sol is JN-30 purchased from Yuanyang County Lutong Refractory Materials Co., Ltd.; the commercially available rinsing liquid is No. 120 solvent oil purchased from Changzhou Aozun Composite New Materials Co., Ltd.; the remaining reagents and equipment are conventional reagents and equipment in this technical field.

[0041] Preparation of surface modifier-1

[0042] Surface modifier-1 was prepared by the following steps: by weight,

[0043] (1) In a reactor, add 1.5 parts of ethyl orthosilicate, 0.1 parts of p-toluenesulfonic acid and 5 parts of anhydrous ethanol, and stir evenly to form solution a;

[0044] (2) In a reactor, add 1 part of N-(2-N-benzylaminoethyl)-3-aminopropyltrimethoxysilane, 0.8 parts of acetoxyethyltrimethoxysilane and 5 parts of anhydrous ethanol, and stir evenly to form solution b;

[0045] (3) In a reactor, 8 parts of solution a and 5 parts of solution b were added, the temperature was raised to 50° C., stirred and reacted for 4 hours, and then cooled to obtain the surface modifier-1.

[0046] Preparation of surface modifier-2

[0047] The preparation method is basically the same as that of surface modifier-1, except that N-(2-N-benzylaminoethyl)-3-aminopropyltrimethoxysilane is replaced by an equal amount of acetoxyethyltrimethoxysilane.

[0048] Example 1

[0049] The recyclable easy-rinse low-density label is prepared by the following steps: by weight,

[0050] (1) In the reactor, add 0.5 parts of potassium permanganate and 9 parts of deionized water, stir evenly, then slowly add 0.2 parts of 98 wt% concentrated sulfuric acid, heat to 40 °C, add low-density heat shrink film, stir and react for 15 minutes, remove the low-density heat shrink film, wash and complete the pretreatment;

[0051] (2) soaking the pretreated low-density heat shrinkable film in surface modifier-1, stirring and reacting for 30 minutes, washing, and drying to obtain the recyclable and easy-to-rinse low-density label;

[0052] The density of the low-density heat shrinkable film is 0.93 g / cm 3 ;

[0053] Recycle recyclable easy rinse low density labels using the following steps:

[0054] (1) Crushing: Crushing the bottle with recyclable, easy-to-rinse, low-density label;

[0055] (2) Flotation: The crushed material is placed in an aqueous solution containing 0.5 wt% of ethylene bis (dodecyl dimethyl ammonium chloride), and after stirring and shaking, the recyclable, easy-to-rinse, low-density label floats on the water surface;

[0056] (3) Rinsing: Transfer the recyclable easy-rinsing low-density labels into the rinsing liquid, heat it to 35°C, stir it for 20 minutes, filter it, wash it, and dry it to achieve the recycling of the recyclable easy-rinsing low-density labels;

[0057] The rinsing liquid is prepared by mixing 10 wt % of ethyl acetate, 5 wt % of pentaerythritol, 1.5 wt % of cocamidopropyl betaine, 3.5 wt % of triethanolamine and 80 wt % of deionized water.

[0058] Example 2

[0059] The same as Example 1, except that the density of the low-density heat shrinkable film is 0.95 g / cm 3 During the flotation process, ethylene bis(dodecyldimethylammonium chloride) was replaced with an equal amount of propylene bis(hexadecyldimethylammonium bromide).

[0060] Example 3

[0061] The same as Example 1, except that the density of the low-density heat shrinkable film is 0.92 g / cm 3 During the flotation process, ethylene bis(dodecyldimethylammonium chloride) was replaced with an equal amount of ethylene bis(octadecyldimethylammonium chloride).

[0062] Comparative Example 1

[0063] The recycling steps are basically the same as those in Example 1, except that the preparation of the recyclable easy-rinsable low-density label is not performed, and the recyclable easy-rinsable low-density label is replaced by a PET heat shrink film.

[0064] Comparative Example 2

[0065] The process is basically the same as Example 1, except that the surface modifier-1 in the preparation of the recyclable, easy-to-rinse, low-density label is replaced by an equal amount of commercially available silica sol.

[0066] Comparative Example 3

[0067] The method is basically the same as Example 1, except that the surface modifier-1 is replaced with an equal amount of surface modifier-2 in the preparation of the recyclable, easy-to-rinse, low-density label.

[0068] Comparative Example 4

[0069] The process is basically the same as Example 1, except that ethylene bis(dodecyldimethylammonium chloride) is not added in the recovery step (2).

[0070] Comparative Example 5

[0071] The process is basically the same as Example 1, except that the rinsing liquid in the recovery step (3) is replaced with an equal amount of commercially available rinsing liquid.

[0072] Performance Testing

[0073] Ink Adhesion Test: According to the cross-cut test method for paints and varnishes (GB / T 9286-2021), the PET heat shrink films of Examples 1-3 and Comparative Example 1, as well as the label films of Comparative Examples 2-3, were printed using conventional water-based inks. The ink adhesion was tested to Grade -1.

[0074] Moisture and heat resistance test: 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 placed in an environment at a temperature of 45°C and a relative humidity of 98% for 144 hours. The adhesion level was then retested according to GB / T 9286-2021 to -2.

[0075] Light resistance test: The PET heat shrinkable films in Examples 1-3 and Comparative Example 1 and the label films in 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 / m 2 After standing in an environment for 36 hours, the adhesion level was tested again according to GB / T 9286-2021 -3.

[0076] The test results are shown in the following table:

[0077]

[0078] According to the comparison of the test results of Examples 1-3 with those of Comparative Example 1, the recyclable, easy-to-rinse, low-density label provided by the present invention has excellent adhesion to ink compared with the label material in the prior art, and can improve the moisture and heat resistance and light resistance of the ink, thereby improving the effect and stability of ink printing.

[0079] According to the comparison of the test results of Examples 1-3 and Comparative Examples 2-3, the recyclable, easy-to-rinse, low-density label provided by the present invention can significantly improve the adhesion and stability of the ink after being modified with a surface modifier, thereby increasing the service life.

[0080] Recovery effect detection: The flotation rates of the labels in Examples 1-3 and Comparative Examples 1-5 and the contents of impurities including ink were detected and recorded respectively.

[0081] The test results are shown in the following table:

[0082]

[0083] According to the comparison of the inspection results of Examples 1-3 and Comparative Example 1, the recyclable, easy-to-rinse low-density labels and the recycling method thereof provided by the present invention have better flotation and rinsing effects than the label materials in the prior art, and can effectively recycle the label materials without impurities, thereby providing its application value.

[0084] According to the comparison of the test results of Examples 1-3 and Comparative Examples 2-3, the recyclable, easy-to-rinse, low-density label and its recycling method provided by the present invention can improve the rinsing effect of the rinsing liquid on its ink and reduce the impurity content by modifying the label material with a surface modifier.

[0085] According to the comparison of the test results of Examples 1-3 and Comparative Examples 4-5, the recyclable, easy-to-rinse, low-density labels and the recycling method thereof provided by the present invention can improve the flotation effect and rinsing effect of the labels by adding a surfactant during the flotation process and using a rinsing liquid with specific components during the rinsing process.

[0086] The above embodiments are only for illustrating the technical concept and features of the present invention. Its purpose is to enable people familiar with this technology to understand the content of the present invention and implement it. It cannot be used to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A recyclable, easy-to-rinse, low-density label, characterized in that: The recyclable easy-to-rinse low-density label is prepared by surface-modifying a low-density heat shrinkable film with a surface modifier; The density of the low-density heat shrinkable film is less than 0.96 g / cm3; The surface modifier is prepared by reacting ethyl orthosilicate, N-(2-N-benzylaminoethyl)-3-aminopropyltrimethoxysilane and acetoxyethyltrimethoxysilane through a sol-gel method; The surface modifier is prepared by the following steps: (1) Add ethyl orthosilicate, p-toluenesulfonic acid and anhydrous ethanol into a reactor and stir to form solution a; (2) Add N-(2-N-benzylaminoethyl)-3-aminopropyltrimethoxysilane, acetoxyethyltrimethoxysilane and anhydrous ethanol into the reactor and stir to form solution b; (3) Add solution a and solution b into a reactor, heat to 40-50°C, stir and react for 4-6 hours, and then cool to obtain the surface modifier.

2. The recyclable easy-rinsing low-density label according to claim 1, characterized in that: The mass ratio of ethyl orthosilicate, p-toluenesulfonic acid and anhydrous ethanol in the solution a is (15-20): (1-2): (35-50).

3. The recyclable easy-rinsing low-density label according to claim 1, characterized in that: The mass ratio of N-(2-N-benzylaminoethyl)-3-aminopropyltrimethoxysilane, acetoxyethyltrimethoxysilane and anhydrous ethanol in the solution b is (10-12): (6-8): (35-50).

4. The recyclable easy-rinsing low-density label according to claim 1, characterized in that: The mass ratio of solution a to solution b in step (3) is (6-8):(4-5).

5. The recyclable easy-rinsing low-density label according to claim 1, characterized in that: The recyclable easy-rinse low-density label is prepared by the following steps: (1) Add potassium permanganate and deionized water to the reactor, stir evenly and then slowly add concentrated sulfuric acid. Heat to 35-40°C and then add low-density heat shrink film. Stir and react for 10-15 minutes, then take out the low-density heat shrink film and wash it to complete the pretreatment. (2) The pretreated low-density heat shrinkable film is immersed in a surface modifier, stirred for reaction for 30-45 minutes, and then washed and dried to obtain the recyclable and easy-to-rinse low-density label.

6. The recyclable easy-rinsing low-density label according to claim 5, characterized in that: The mass fraction of concentrated sulfuric acid in step (1) is 90-98 wt %; the mass ratio of potassium permanganate, concentrated sulfuric acid and deionized water is (5-8): (1-2): (80-90).

7. The method for recycling recyclable easy-rinsable low-density labels according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) Crushing: Crushing the bottle with recyclable, easy-to-rinse, low-density label; (2) Flotation: The crushed material is placed in an aqueous solution containing a surfactant, and after stirring and shaking, the recyclable, easy-to-rinse, low-density label floats on the water surface; (3) Rinsing: Transfer the recyclable easy-rinsing low-density labels into the rinsing liquid, heat it to 35-40°C and stir it for 15-20 minutes, then filter, wash and dry it to achieve the recycling of the recyclable easy-rinsing low-density labels.

8. The method for recycling recyclable easy-rinsable low-density labels according to claim 7, characterized in that: In step (2), the surfactant is selected from one of ethylene bis(dodecyldimethylammonium chloride), propylene bis(hexadecyldimethylammonium bromide) or ethylene bis(octadecyldimethylammonium chloride); the amount of the surfactant added is 0.3-1 wt% of the mass of water.

9. The method for recycling recyclable easy-rinsable low-density labels according to claim 7, characterized in that: The rinsing liquid in step (3) is prepared by mixing ethyl acetate, pentaerythritol, cocamidopropyl betaine, triethanolamine and deionized water.

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