Environment-friendly fragrant packaging film and preparation method thereof

Abstract

The invention provides an environment-friendly fragrant packaging film and a preparation method thereof, and relates to the field of packaging materials, the environment-friendly fragrant packaging film comprises a base film and a functional layer formed by coating the surface of the base film with a coating liquid, the coating liquid is prepared from the following components in parts by mass: 20 to 25 parts of waterborne polyurethane, 40 to 50 parts of waterborne acrylic acid, 2 to 8 parts of fragrant microcapsules, 0.5 to 1 part of a waterborne cross-linking agent, 0.5 to 1 part of isopropanol, 0.5 to 1.5 parts of propylene glycol monomethyl ether, 1 to 2 parts of a wetting agent, 0.5 to 1 part of a de-foaming agent and de-ionized water; the fragrant microcapsule and the water-based resin system are fused to prepare the fragrant packaging film, and due to the adoption of the water-based coating system, the fragrant packaging film is environment-friendly and suitable for industrial production; meanwhile, isopropyl alcohol and propylene glycol monomethyl ether are creatively compounded and applied to a water-based coating liquid system containing the fragrant microcapsules, and the technical problems that the fragrant microcapsules are poor in dispersion stability and prone to agglomeration in a water-based resin system are effectively solved.

Description

Technical Field

[0001] This invention relates to the field of packaging materials technology, specifically to an environmentally friendly scented packaging film and its preparation method. Background Technology

[0002] As the consumer market continues to upgrade, consumers' demands for products are no longer limited to basic functions, but rather they pursue personalized and differentiated experiences. From a market development perspective, the demand for personalized and functional products is growing, and the application areas of fragrance films are constantly expanding. They can be widely used in packaging, decoration, textiles, and other fields, giving products unique fragrance experiences and functional characteristics. For example, in food packaging, fragrance films can release natural fruit aromas to enhance product appeal; in interior decoration, they can release soothing fragrances according to environmental changes, creating a comfortable living environment. These applications can satisfy consumers' pursuit of a better life and improve the quality of life for the general public.

[0003] Currently, the main methods for preparing scented films are melt co-extrusion and coating. Melt co-extrusion involves mixing the scented substance with a resin substrate and then co-extruding it into a film using an extruder, as shown in patent application CN118952795A, which discloses a scented cigarette packaging film. However, such extrusion processes lead to the loss of scented substances through volatilization during processing, and the release rate is difficult to control, resulting in a significant weakening or even disappearance of the scent within a short period. Coating, on the other hand, involves dispersing the scented substance in a coating solution and then coating it onto the substrate surface, which can reduce scent loss. For example, patent application CN107163553A discloses a scented PU film using an oil-based resin as a matrix, with microcapsule fragrance applied to the coating solution. However, films produced by this coating method suffer from poor coating adhesion, excessively rapid or uneven scent release, and the tendency to generate bubbles during the coating process. Furthermore, it also presents problems with poor environmental compatibility.

[0004] While aqueous coating systems are environmentally friendly, the application of fragrance microcapsules in these systems is severely limited. The main reason for this is the technical bottleneck of achieving a balance between the compatibility and stability of the fragrance microcapsules and the coating solution. This poor compatibility and stability leads to poor dispersion stability of the microcapsules in the coating solution, making them prone to aggregation and sedimentation. Consequently, defects such as pinholes and craters are easily generated on the film surface during coating. Furthermore, after film drying, the weak adhesion between the microcapsules and the substrate makes them prone to detaching from the coating surface, resulting in a significantly shortened fragrance retention time and affecting the integrity and mechanical properties of the coating.

[0005] Therefore, this application aims to provide an environmentally friendly fragrance packaging film with good surface finish and more stable performance, as well as a method for its preparation. Summary of the Invention

[0006] This invention addresses the aforementioned problems in the prior art by providing an environmentally friendly fragrance packaging film and its preparation method. It solves the compatibility problem between fragrance microcapsules and the coating liquid matrix, resulting in a fragrance film with good surface finish and more stable performance, achieving long-lasting fragrance release and excellent coating performance.

[0007] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: On one hand, the present invention provides an environmentally friendly scented packaging film, characterized in that it comprises a base film and a functional layer formed by coating a coating liquid on the surface of the base film. The coating liquid comprises the following components and their mass parts: 20-25 parts of waterborne polyurethane, 40-50 parts of waterborne acrylic acid, 2-8 parts of scented microcapsules, 0.5-1 part of waterborne crosslinking agent, 0.5-1 part of isopropanol, 0.5-1.5 parts of propylene glycol methyl ether, 1-2 parts of wetting agent, 0.5-1 part of defoamer, and deionized water.

[0008] Furthermore, the base film is a PET film, preferably with a film thickness of 8-20 μm, and the thickness of the functional layer is preferably 2-8 μm.

[0009] Furthermore, the waterborne polyurethane is an aliphatic waterborne polyurethane, and the waterborne acrylic is a self-crosslinking waterborne acrylic emulsion. The combination of these two resins gives the prepared fragrance film both excellent mechanical properties and protective properties for the microcapsules, ensuring the longevity of its fragrance release.

[0010] Furthermore, the fragrance microcapsules are wall-encapsulated microcapsules, with the wall material being melamine resin or polyurethane and the core material being a fragrance-rich essential oil or perfume.

[0011] Furthermore, the mass ratio of isopropanol to propylene glycol methyl ether is 1:0.5-1.5. This specific combination of isopropanol and propylene glycol methyl ether has two advantages: firstly, isopropanol can effectively reduce the surface tension of the system and promote the wetting of microcapsules; secondly, some of the lipophilic groups in propylene glycol methyl ether can be better anchored on the hydrophobic surface of the microcapsules, while the hydrophilic groups are compatible with isopropanol and the aqueous phase. This results in a stronger and more stable transition layer between the microcapsules and the resin matrix, significantly improving dispersion stability and the overall performance of the final coating.

[0012] Furthermore, the aqueous crosslinking agent is a aziridine-based or isocyanate-based crosslinking agent.

[0013] Furthermore, the wetting agent is a polyether-modified silicone wetting agent, and the defoamer is a mineral oil-based or silicone-based defoamer.

[0014] On the other hand, the present invention provides a method for preparing the environmentally friendly scented packaging film as described above, characterized by comprising the following steps: The surface of the base film to be coated is subjected to corona treatment to make its surface dyne value ≥ 56 dyne / cm; the coating liquid is applied to the surface of the base film and dried to obtain the fragrance packaging film.

[0015] Furthermore, the preparation method of the coating liquid is as follows: waterborne polyurethane resin and waterborne acrylic acid are dispersed evenly, and then pretreated fragrance microcapsules, waterborne crosslinking agent, isopropanol, wetting agent, defoamer and deionized water are added to it and mixed evenly to obtain the coating liquid.

[0016] Furthermore, the pretreatment method for the fragrance microcapsules is as follows: the fragrance microcapsules are mixed evenly with propylene glycol methyl ether.

[0017] The beneficial effects of this invention are: 1. This invention uses a combination of fragrance microcapsules and an aqueous resin system to prepare a fragrance packaging film. Due to the use of an aqueous coating system, it is environmentally friendly and can be widely used in food packaging, daily necessities packaging and other fields, and is suitable for industrial production.

[0018] 2. This invention creatively combines isopropanol and propylene glycol methyl ether in an aqueous coating system containing fragrance microcapsules. The two work synergistically to effectively solve the technical problems of poor dispersion stability and easy aggregation of fragrance microcapsules in aqueous resin systems. This solves the compatibility problem of fragrance microcapsules in this aqueous system, overcomes the technical bottleneck of applying fragrance microcapsules in aqueous systems, and produces a fragrance packaging film with good surface effect, excellent coating performance, stable overall quality, and controllable fragrance release. Detailed Implementation

[0019] The principles and features of the present invention are described below. The embodiments given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0020] Example 1 The coating liquid in this embodiment mainly includes the following components and their weight proportions: 20 parts waterborne polyurethane (brand name 7625, solid content 35%, Guangzhou Hangeng New Materials Co., Ltd.), 40 parts self-crosslinking waterborne acrylic emulsion (brand name 309A, solid content 40%, Guangzhou Sanheshun Technology Co., Ltd.), 5 parts fragrance microcapsules (solid content 5%, wall material is melamine resin, core material is jasmine fragrance, Meisheng Biotechnology), 1 part waterborne crosslinking agent (brand name 160, Guangzhou Hangeng New Materials Co., Ltd.), 1 part isopropanol, 1.5 parts propylene glycol methyl ether, 2 parts wetting agent (brand name 5005, Guangzhou Hangeng New Materials Co., Ltd.), 1 defoamer (brand name 6525, Guangzhou Hangeng New Materials Co., Ltd.), and a small amount of deionized water.

[0021] The fragrance film in this embodiment is prepared according to the following steps: (1) Preparation of base film: PET base film with a thickness of 12μm is used, double-sided corona treatment, and the corona value is ≥56 dyne / cm; (2) Preparation of coating solution: Aqueous polyurethane resin solution was added to aqueous acrylic resin solution and dispersed using a magnetic stirrer at a speed of 350-500 r / min to obtain a mixed film-forming substance dispersion. After the flavor microcapsules are mixed evenly with propylene glycol methyl ether, they are added to the dispersion and mixed evenly using a magnetic stirrer at a speed of 200-350 r / min. Add the above-mentioned isopropanol, wetting agent, defoamer, deionized water and water-based crosslinking agent to the mixture and continue stirring for 3-5 minutes until the mixture is homogeneous to obtain the coating solution.

[0022] (3) Coating The coating liquid is evenly applied to the surface of the base film using a coating machine at a speed of 10 m / min. The film is then dried in an oven at 60°C to obtain a fragrance film with a coating thickness of 2-4 μm.

[0023] Example 2 The coating liquid in this embodiment mainly includes the following components and their weight proportions: 25 parts waterborne polyurethane (brand name 7625, solid content 35%, Guangzhou Hangeng New Materials Co., Ltd.), 50 parts self-crosslinking waterborne acrylic emulsion (brand name 309A, solid content 40%, Guangzhou Sanheshun Technology Co., Ltd.), 2 parts fragrance microcapsules (solid content 5%, wall material is melamine resin, core material is jasmine fragrance, Meisheng Biotechnology), 0.5 parts waterborne crosslinking agent (brand name 160, Guangzhou Hangeng New Materials Co., Ltd.), 1 part isopropanol, 0.5 parts propylene glycol methyl ether, 1 part wetting agent (brand name 5005, Guangzhou Hangeng New Materials Co., Ltd.), 0.5 parts defoamer (brand name 6525, Guangzhou Hangeng New Materials Co., Ltd.), and a small amount of deionized water.

[0024] The fragrance film in this embodiment is prepared according to the following steps: (1) Preparation of base film: PET base film with a thickness of 12μm is used, double-sided corona treatment, and the corona value is ≥56 dyne / cm; (2) Preparation of coating solution: Aqueous polyurethane resin solution was added to aqueous acrylic resin solution and dispersed using a magnetic stirrer at a speed of 350-500 r / min to obtain a mixed film-forming substance dispersion. After the flavor microcapsules are mixed evenly with propylene glycol methyl ether, they are added to the dispersion and mixed evenly using a magnetic stirrer at a speed of 200-350 r / min. Add the above-mentioned isopropanol, wetting agent, defoamer, deionized water and water-based crosslinking agent to it, and continue stirring for 3-5 minutes until it is evenly mixed to obtain the coating liquid.

[0025] (3) Coating The coating liquid is evenly applied to the surface of the base film using a coating machine at a speed of 10 m / min. The film is then dried in an oven at 60°C to obtain a fragrance film with a coating thickness of 2-4 μm.

[0026] Example 3 The coating liquid in this embodiment mainly includes the following components and their weight proportions: 20 parts waterborne polyurethane (brand name 7625, solid content 35%, Guangzhou Hangeng New Materials Co., Ltd.), 40 parts self-crosslinking waterborne acrylic emulsion (brand name 309A, solid content 40%, Guangzhou Sanheshun Technology Co., Ltd.), 8 parts fragrance microcapsules (solid content 5%, wall material is melamine resin, core material is jasmine fragrance, Meisheng Biotechnology), 0.5 parts waterborne crosslinking agent (brand name 160, Guangzhou Hangeng New Materials Co., Ltd.), 1 part isopropanol, 1.0 part propylene glycol methyl ether, 1 part wetting agent (brand name 5005, Guangzhou Hangeng New Materials Co., Ltd.), 0.5 parts defoamer (brand name 6525, Guangzhou Hangeng New Materials Co., Ltd.), and a small amount of deionized water.

[0027] The fragrance film in this embodiment is prepared according to the following steps: (1) Preparation of base film: PET base film with a thickness of 12μm is used, double-sided corona treatment, and the corona value is ≥56 dyne / cm; (2) Preparation of coating solution: Aqueous polyurethane resin solution was added to aqueous acrylic resin solution and dispersed using a magnetic stirrer at a speed of 350-500 r / min to obtain a mixed film-forming substance dispersion. After the flavor microcapsules are mixed evenly with propylene glycol methyl ether, they are added to the dispersion and mixed evenly using a magnetic stirrer at a speed of 200-350 r / min. Add the above-mentioned isopropanol, wetting agent, defoamer, deionized water and water-based crosslinking agent to it, and continue stirring for 3-5 minutes until it is evenly mixed to obtain the coating liquid.

[0028] (3) Coating The coating liquid is evenly applied to the surface of the base film using a coating machine at a speed of 10 m / min. The film is then dried in an oven at 60°C to obtain a fragrance film with a coating thickness of 2-4 μm.

[0029] Comparative Example 1 The coating liquid formulation and fragrance film preparation method of this comparative example are basically the same as those in Example 1, except that the waterborne polyurethane in the coating liquid is replaced with an equal mass of waterborne acrylic acid (same as in Example 1).

[0030] Comparative Example 2 The coating liquid formulation and fragrance film preparation method of this comparative example are basically the same as those of Example 1. The difference is that the fragrance microcapsules in the coating liquid are replaced with core material fragrance (with the same mass as the core material of the fragrance microcapsules in Example 1).

[0031] Comparative Example 3 The coating solution formulation and fragrance film preparation method of this comparative example are basically the same as those in Example 1, except that isopropanol and propylene glycol methyl ether are not added to the coating solution.

[0032] Comparative Example 4 The coating solution formulation and fragrance film preparation method of this comparative example are basically the same as those in Example 1, except that isopropanol and propylene glycol methyl ether in the coating solution are replaced with an equal amount of ethanol.

[0033] Comparative Example 5 The coating liquid formulation and fragrance film preparation method of this comparative example are basically the same as those in Example 1, except that the isopropanol and propylene glycol methyl ether in the coating liquid are replaced with an equal amount of n-propanol.

[0034] Comparative Example 6 The coating solution formulation and fragrance film preparation method of this comparative example are basically the same as those in Example 1, except that propylene glycol methyl ether was not added to the coating solution.

[0035] Comparative Example 7 The coating solution formulation and fragrance film preparation method of this comparative example are basically the same as those in Example 1, except that isopropanol was not added to the coating solution.

[0036] The performance of the samples from the examples and comparative examples was tested according to the following methods, and the performance parameters are shown in Table 1: (1) Fragrance persistence: subjective evaluation; (2) Adhesion: According to the national standard GB / T13217.7-2023, the cross-cut adhesion test is adopted, and the adhesion level is 0-5, with level 0 being the best; (3) Film surface effect: visual inspection; (4) Aroma stability: subjective evaluation.

[0037] Table 1

[0038] As shown in Table 1, the fragrance film prepared in the embodiments of the present invention has excellent fragrance persistence, retaining a noticeable fragrance even after 180 days. Furthermore, the film exhibits strong adhesion, no obvious defects on the film surface, and good surface finish. In contrast, in Comparative Example 1, replacing the waterborne polyurethane with an equal mass of waterborne acrylic acid significantly reduced adhesion. In Comparative Examples 3-7, replacing at least one of isopropanol and propylene glycol methyl ether in the coating solution with other substances resulted in films with persistent fragrance, but a significant increase in surface defects. This may be due to poor compatibility between materials in the coating solution system, leading to poor dispersion stability and easy aggregation of microcapsules in the coating solution, thus causing obvious defects on the coated film surface.

Claims

1. An environmentally friendly scented packaging film, characterized in that, It includes a base film and a functional layer formed by coating the surface of the base film with a coating liquid. The coating liquid comprises the following components and their mass parts: 20-25 parts of waterborne polyurethane, 40-50 parts of waterborne acrylic acid, 2-8 parts of fragrance microcapsules, 0.5-1 part of waterborne crosslinking agent, 0.5-1 part of isopropanol, 0.5-1.5 parts of propylene glycol methyl ether, 1-2 parts of wetting agent, 0.5-1 part of defoamer, and deionized water.

2. The environmentally friendly scented packaging film according to claim 1, characterized in that, The base film is a PET film.

3. The environmentally friendly scented packaging film according to claim 1, characterized in that, The waterborne polyurethane is an aliphatic waterborne polyurethane.

4. The environmentally friendly scented packaging film according to claim 1, characterized in that, The fragrance microcapsules are wall-encapsulated microcapsules, with the wall material being melamine resin or polyurethane and the core material being a fragrant essential oil or fragrance.

5. The environmentally friendly scented packaging film according to claim 1, characterized in that, The mass ratio of isopropanol to propylene glycol methyl ether is 1:0.5-1.

5.

6. The environmentally friendly scented packaging film according to claim 1, characterized in that, The aqueous crosslinking agent is a aziridine-based or isocyanate-based crosslinking agent.

7. The environmentally friendly scented packaging film according to claim 1, characterized in that, The wetting agent is a polyether-modified organosilicon wetting agent, and the defoamer is a mineral oil-based or organosilicon-based defoamer.

8. The method for preparing the environmentally friendly scented packaging film according to any one of claims 1-7, characterized in that, Includes the following steps: The surface of the base film to be coated is subjected to corona treatment to make its surface dyne value ≥ 56 dyne / cm; the coating liquid is applied to the surface of the base film and dried to obtain the fragrance packaging film.

9. The preparation method according to claim 8, characterized in that, The coating liquid is prepared by dispersing waterborne polyurethane resin and waterborne acrylic acid evenly, then adding pretreated fragrance microcapsules, waterborne crosslinking agent, isopropanol, wetting agent, defoamer and deionized water, and mixing evenly to obtain the coating liquid.

10. The preparation method according to claim 9, characterized in that, The pretreatment method for the fragrance microcapsules is as follows: the fragrance microcapsules are mixed evenly with propylene glycol methyl ether.

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