A polyurethane coating and its preparation method and its application in preparing cigarette packaging paper

Abstract

The present invention relates to a polyurethane coating and a preparation method thereof and an application thereof in preparing cigarette packaging paper, and belongs to the technical field of polyurethane coating. The coating comprises the following components in parts by weight: 85-105 parts of an environmentally friendly water-based resin; 0.5-1.5 parts of silicon dioxide, 5-8 parts of aluminum oxide, 0.2-0.4 parts of a leveling agent, and 0.3-0.6 parts of a defoaming agent; wherein the environmentally friendly water-based resin is an aqueous anionic polyurethane resin. The polyurethane coating of the present invention has good adhesion, wear resistance, barrier properties, and environmental protection characteristics. Applying the polyurethane coating to cigarette packaging can reduce the pollution of cigarette packaging to the environment, which meets the requirements of sustainable development.

Description

Technical Field

[0001] The invention relates to the technical field of polyurethane coatings, and in particular to a polyurethane coating and a preparation method thereof and application thereof in the preparation of cigarette packaging paper. Background Art

[0002] Cigarettes are a commodity for consumers to smoke. Similar to ordinary food, the environmental protection, hygiene and safety of cigarette products have always been of great concern to consumers and the tobacco industry. According to the relevant definition of indirect additives of food and drugs by the US FDA, restricted substances that migrate from cigarette contact materials such as cigarette packaging paper and printing ink and remain in cigarettes should be considered indirect additives of cigarette products. Since cigarettes are directly touched and smoked by smokers, such pollutants potentially in cigarettes will pose a considerable threat to human health and the environment. At the same time, this is also one of the important factors affecting the quality of cigarette smoking.

[0003] At present, while colorful cigarette packaging brings great convenience to our lives, the printing ink on the surface of cigarette packaging has become a potential source of cigarette pollution. Benzophenone (BP) and 4-methylbenzophenone (4-MBP) in printing inks are ultraviolet (UV) absorbers (absorbing ultraviolet wavelengths of 290-360nm) and initiators. They are widely used in UV inks, but long-term contact with cigarettes may pose a health hazard. In addition, the above-mentioned UV coatings also have the problem of poor wear resistance. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a polyurethane coating having the advantages of good adhesion, excellent wear resistance, safety, non-toxicity and environmental protection, and a preparation method thereof and application in the preparation of cigarette packaging paper.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] In a first aspect, the present invention provides a polyurethane coating comprising the following components in parts by weight: 85-105 parts of an environmentally friendly water-based resin; 0.5-1.5 parts of silicon dioxide, 5-8 parts of aluminum oxide, 0.2-0.4 parts of a leveling agent, and 0.3-0.6 parts of a defoaming agent; wherein the environmentally friendly water-based resin is a water-based anionic polyurethane resin.

[0007] The water-retaining resin used in the present invention is an aqueous anionic polyurethane ink resin, which does not contain VOC (volatile organic compounds), greatly reducing the harm to the environment and human body. Moreover, compared with traditional polymer materials, the aqueous resin has better biodegradability. Moreover, the anionic aqueous polyurethane ink resin can maintain stable performance under high and low temperature environments, and has a fast drying speed, which can effectively improve production efficiency, and also help to keep the surface of the product clean and tidy, and reduce the generation of dust. Moreover, the resin is liquid at room temperature, and has good fluidity, which makes it easy to operate in coating, printing and dyeing processes, and improves production efficiency and product quality.

[0008] The environmentally friendly water-based resin is a single-component, water-based, free-isocyanate monomer anionic polyester polyurethane resin. More preferably, it is a mixture of AH-1502E and AH-1502F of Anhui Dawei Huatai New Material Technology Co., Ltd.; wherein AH-1502E is 55-65 parts and AH-1502F is 30-40 parts. The above two components are both single-component, water-based, free-isocyanate monomer anionic polyester polyurethane resins, and the combination of the two has a synergistic effect and can significantly improve the adhesion and wear resistance of the coating.

[0009] Preferably, the leveling agent is an organosilicon leveling agent. Organosilicon leveling agents can significantly reduce the surface tension of the coating, improve the substrate wetting ability of the coating and the fluidity of the paint film. This leveling agent can also improve the smoothness, scratch resistance and adhesion resistance of the coating. However, this type of leveling agent may have a tendency to stabilize foam and affect interlayer adhesion. In cigarette production, organosilicon leveling agents can be used to improve the smoothness and glossiness of cigarette packaging.

[0010] Preferably, the defoamer is an organosilicon defoamer. This type of defoamer mainly contains hydrophobic silicone oil as an active ingredient and has an excellent defoaming effect. In cigarette production, organosilicon defoamers can effectively eliminate the foam generated during the production process, thereby improving production efficiency and product quality.

[0011] Preferably, the particle size of the nano silicon dioxide is 10-40 nm. This ultra-fine silicon dioxide has high sedimentation activity, strong adsorption and high specific surface area, and is suitable for use in cigarettes, such as improving combustion performance or as a combustion aid.

[0012] Preferably, the particle size of the nano-alumina is 20-40 nm, preferably 30 nm. This ultra-fine particle size alumina may be used in certain specific parts of cigarettes, such as improving combustion performance or as a combustion aid, and may also be used to prepare special filter materials.

[0013] The present invention uses nano-scale silicon dioxide and aluminum oxide, which can effectively improve the barrier properties of the coating, effectively prevent the penetration of substances such as oxygen and moisture, thereby extending the shelf life of cigarettes. It can also enhance the wear resistance of cigarette packaging, making it more durable and reducing damage during transportation and storage. The nano coating has a unique gloss and texture, which can enhance the aesthetics of cigarette packaging and attract the attention of consumers. In addition, nano inorganic fillers have excellent anti-ultraviolet properties. Adding them to cigarette coatings can effectively improve the anti-ultraviolet ability of the coating, thereby delaying the aging process of the coating and increasing the service life of the coating. In addition, due to the small size effect and high specific surface area of ​​the nano inorganic filler particles, they can improve the rheological properties of the coating, make the coating easier to apply, and improve the quality and uniformity of the coating.

[0014] In a second aspect, the present invention provides a method for preparing a polyurethane coating, comprising the following steps:

[0015] Firstly, all components of the polyurethane coating are pre-dispersed to obtain a mixture, and then the mixture is ground and filtered to obtain the polyurethane coating.

[0016] Preferably, the pre-dispersion parameters are: a dispersion speed of 500 to 1500 rpm / min, a temperature of 20 to 40° C., and a time of 10 to 40 min.

[0017] Preferably, the particle size of the milled mixture is <1 μm.

[0018] In a third aspect, the present invention provides an application of a polyurethane coating in the preparation of cigarette packaging paper. The use of a specific polyurethane coating to prepare the coating on the cigarette packaging paper means that after the cigarette packaging paper is used, the water-based resin can be more easily decomposed by nature, thereby reducing the long-term impact on the environment. It can also enable the cigarette packaging paper to maintain its original aesthetics and functionality under various climatic conditions.

[0019] Preferably, the method for using the polyurethane coating comprises the following steps: applying the polyurethane coating on the surface of cigarette packaging paper, and then curing the coating to form a coating on the cigarette packaging paper.

[0020] Preferably, the material of the surface of the cigarette packaging paper is polyethylene terephthalate (PET) or biaxially oriented polypropylene film (BOPP), and its polyurethane coating has excellent adhesion to PET and BOPP materials.

[0021] Preferably, the coating amount of the polyurethane coating is 8 to 20 g / m 2; The curing temperature is 150-300℃; The time is 1-5h. There are two main curing methods: one is self-drying at room temperature, that is, letting the nano solution dry naturally at a temperature of about 25℃, which usually requires waiting for about 24 hours. The other is drying, that is, setting the temperature at 100-120℃ through a heating device to allow the nano solution to dry in a shorter time (about 20 to 30 minutes). The curing temperature of nano coatings is usually between 150℃ and 300℃. Curing time is also a key factor, usually between 1 hour and 5 hours. Too short a time may result in insufficient hardness and wear resistance of the coating surface, while too long a time may make the coating material brittle, thereby affecting its performance. The use of the above parameters can enable the polyurethane coating to form a uniform, dense and highly adhesive coating on the surface of the packaging paper.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The polyurethane coating of the present invention does not add UV absorbers and initiators, which can greatly reduce the potential safety hazards of the coating. In addition, the environmentally friendly water-based resin of anionic water-based polyurethane ink resin is selected as the basic film-forming material of the coating, which can effectively improve the adhesion of the coating. Moreover, it does not contain VOC, which greatly reduces the harm to the environment and human body. Silicon dioxide and aluminum oxide are also introduced into the coating as performance enhancing additives, which can effectively enhance the wear resistance of the coating. The addition of these nanomaterials significantly improves the adhesion, wear resistance and environmental protection characteristics of the coating. At the same time, the leveling agent and defoaming agent are used to optimize the coating smoothness and defoaming performance of the coating. The polyurethane coating is applied to cigarette packaging, which can reduce the pollution of cigarette packaging to the environment and meet the requirements of sustainable development. DETAILED DESCRIPTION

[0024] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0025] The reagents involved in the following examples are as follows:

[0026] Water-based anionic polyurethane resin: the manufacturer is Anhui Dawei Huatai New Material Technology Co., Ltd., the brand is AH-1502E, AH-1502F;

[0027] Unless otherwise specified, other materials, reagents, etc. used in the examples can be obtained from commercial sources.

[0028] Examples 1 to 7

[0029] The components of Examples 1 to 7 are shown in Table 1.

[0030] The preparation method of the polyurethane coating of Examples 1 to 7 is:

[0031] First, all components of the polyurethane coating are pre-dispersed to obtain a mixture, and then the mixture is ground to a particle size of less than 1 μm, and filtered to obtain the polyurethane coating. The pre-dispersion parameters are: a dispersion speed of 500 to 1500 rpm / min, a temperature of 20 to 40° C., and a time of 10 to 40 minutes.

[0032] Table 1 Formulation of polyurethane coatings of Examples 1 to 7

[0033]

[0034] Example 8

[0035] The difference between Example 8 and Example 1 is that in Example 8, AH-1502E is replaced by polyurethane resin AH-1720A from the same manufacturer.

[0036] Example 9

[0037] The difference between Example 9 and Example 1 is that in Example 8, AH-1502F is replaced by polyurethane resin AH-1720A from the same manufacturer.

[0038] Example 10

[0039] The difference between Example 10 and Example 1 is that the particle size of silicon dioxide and aluminum oxide in Example 10 is 10 μm.

[0040] Comparative Example 1

[0041] The difference between Comparative Example 1 and Example 1 is that in Comparative Example 1, the waterborne polyurethane resin is replaced by acrylic resin.

[0042] Comparative Example 2

[0043] The difference between Comparative Example 2 and Example 1 is that: in Comparative Example 2, 6 parts of silicon dioxide and 1 part of aluminum oxide are added.

[0044] Coating Application

[0045] The polyurethane coatings of Examples 1 to 10 and Comparative Examples 1 to 2 were respectively applied to prepare cigarette packaging, corresponding to Application Examples 1 to 10 and Comparative Application Examples 1 to 2, respectively.

[0046] Application Examples 1 to 10 and Comparative Application Examples 1 to 2

[0047] The method for using the polyurethane coating comprises the following steps: applying the polyurethane coating on the surface of cigarette wrapping paper, and then curing the coating to form a coating on the cigarette wrapping paper. The material of the surface of the cigarette wrapping paper is polyethylene terephthalate (PET). The coating amount of the polyurethane coating is 15 g / m 2; The curing temperature is 200℃; The time is 2h.

[0048] Comparative Application Example 3

[0049] Comparative Application Example 3 uses the polyurethane coating of Example 1, and the difference between it and Application Example 1 is that the curing temperature of Comparative Application Example 3 is 140° C. and the curing time is 5.5 hours.

[0050] Comparative Application Example 4

[0051] Comparative Application Example 4 uses the polyurethane coating of Example 1, and the difference between it and Application Example 1 is that the curing temperature of Comparative Application Example 4 is 310° C. and the curing time is 0.5 h.

[0052] Performance Testing

[0053] The cigarette packaging papers of Application Examples 1 to 10 and Comparative Application Examples 1 to 4 were subjected to the following tests:

[0054] 1. Adhesion test at room temperature and high temperature: Place each group of samples at room temperature (25-30℃), 150℃ and 200℃ for 24 hours, then take them out to test the shear strength and pull-off strength of the coating.

[0055] 2. Abrasion resistance test: Tested according to the method shown in ASTM D 4060-19, grinding wheel CS-17, load 1000g.

[0056] 3. Gloss test: Measure according to the method shown in GB / T9754, 60°.

[0057] 4. Barrier performance test: Use a water vapor permeability tester to test the water vapor permeability. According to the method of GB / T1038-2000, use a gas permeability tester to measure the oxygen permeability of the packaging paper.

[0058] The above test results are detailed in Table 2.

[0059] Table 2 Test results of the coating of cigarette packaging paper of application examples 1 to 10 and comparative application examples 1 to 3

[0060]

[0061]

[0062] It can be seen from Table 2 that the adhesion, wear resistance and barrier effect of the coatings of Application Examples 4 to 5 and Application Examples 8 to 9 are lower than those of Application Example 1. This is because only one water-based resin is added in Application Examples 4 to 5, and AH-1502E or AH-1502F is replaced with other types of polyurethane resins in Application Examples 8 to 9 respectively. Combined with the data, it can be seen that the combination of AH-1502E and AH-1502F selected in Example 1 has a synergistic effect and can maintain stable performance in high and low temperature environments, which enables the cigarette packaging paper to maintain its original aesthetics and functionality under various climatic conditions.

[0063] The adhesion, abrasion resistance and barrier effect of the coating of Application Example 6-7 are also lower than those of Application Example 1. The total amount of water-based resin in Examples 6-7 and Example 1 is the same, but the ratio between AH-1502E and AH-1502F is different. If it is lower than 55-65 parts of AH-1502E and higher than 30-40 parts of AH-1502F, it will cause the "broken package" phenomenon. If it is higher than 55-65 parts of AH-1502E and lower than 30-40 parts of AH-1502F, it will affect the tensile strength and barrier properties of the coating, and also affect the subsequent processing of the coating. Therefore, setting AH-1502E to 55-65 parts and AH-1502F to 30-40 parts in the water-based resin can obtain a polyurethane coating with the best performance, thereby obtaining a packaging coating with the best performance.

[0064] The adhesion, wear resistance and barrier effect of the coating of Application Example 10 are also lower than those of Application Example 1. This is because the aluminum dioxide and silicon dioxide added to the coating of Example 10 are both micron-sized, which reduces the uniformity and adhesion of the coating during coating. Application Example 1 uses nano-sized aluminum dioxide and silicon dioxide, which can form a uniform and dense coating on the surface of the packaging paper during subsequent coating, which can significantly improve the barrier properties, wear resistance, aesthetics and environmental protection performance of the cigarette packaging.

[0065] The coating of comparative application example 1 is acrylic resin, and its adhesion and wear resistance are not as good as those of application examples 1, 8 to 9, which shows that compared with this resin, polyurethane can greatly improve the barrier property, wear resistance and aesthetics of the coating.

[0066] The addition amount of silicon dioxide and aluminum oxide in the coating of comparative application example 2 is opposite to that in application example 1. The addition amount of aluminum oxide in the coating of the present invention is significantly more than that of silicon dioxide. This is determined by chemical properties and stability: aluminum oxide is an inorganic oxide with high hardness and heat resistance, which enables it to provide stable performance in the cigarette manufacturing process. In contrast, although silicon dioxide also has its unique properties, such as high sedimentation activity and strong adsorption, it may not be as stable as aluminum oxide in terms of operation.

[0067] During the curing process of the coating of comparative application example 3, the curing time is too long, causing the coating material to become brittle. During the curing process of the coating of comparative application example 4, the temperature is too high, resulting in excessive volatilization of volatile substances in the resin when the composite material or epoxy resin is cured at too high a temperature. This will cause the resin to shrink, and then produce holes and cracks in the product. This is caused by the accelerated chemical reaction rate and increased side reactions caused by high temperature. At a suitable temperature, the resin can form a stable three-dimensional network structure, thereby improving the performance of the product. However, when the temperature is too high, this stable structure may be destroyed. These defects not only affect the appearance of the product, but more importantly, they will reduce the quality and performance of the product.

[0068] In summary, the polyurethane coating of the present invention can exert excellent adhesion, wear resistance, barrier properties and aesthetics on cigarette packaging paper by limiting key aspects such as the selection and dosage of water-based resin, the ratio of nano-inorganic materials, the selection and addition amount of additives, the optimization of pre-dispersion and grinding processes, and the precise control of coating parameters.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A polyurethane coating, characterized in that: The invention comprises the following components in parts by weight: 85-105 parts of an environmentally friendly water-based resin; 0.5-1.5 parts of silicon dioxide, 5-8 parts of aluminum oxide, 0.2-0.4 parts of a leveling agent, and 0.3-0.6 parts of a defoaming agent; the environmentally friendly water-based resin is a mixture of AH-1502E and AH-1502F; the particle size of the silicon dioxide is 10-40 nm; and the particle size of the aluminum oxide is 20-40 nm.

2. The polyurethane coating according to claim 1, characterized in that At least one of the following (I) to (II): (I) The leveling agent is an organosilicon leveling agent; (II) The defoaming agent is an organosilicon defoaming agent.

3. The method for preparing the polyurethane coating according to claim 1 or 2, characterized in that: The following steps are involved: Firstly, all components of the polyurethane coating are pre-dispersed to obtain a mixture, and then the mixture is ground and filtered to obtain the polyurethane coating.

4. The method for preparing the polyurethane coating according to claim 3, characterized in that: The parameters of the pre-dispersion are: a dispersing rotation speed of 500 to 1500 rpm / min, a temperature of 20 to 40° C., and a time of 10 to 40 min.

5. The method for preparing the polyurethane coating according to claim 3, characterized in that: The particle size of the milled mixture was <1 μm.

6. Use of the polyurethane coating according to claim 1 or 2 in the preparation of cigarette packaging paper.

7. The use of the polyurethane coating as claimed in claim 6 in preparing cigarette packaging paper, characterized in that: The method for using the polyurethane coating comprises the following steps: coating the polyurethane coating on the surface of cigarette packaging paper, and then curing the coating to form a coating on the cigarette packaging paper.

8. The use of the polyurethane coating as claimed in claim 7 in preparing cigarette packaging paper, characterized in that: The coating amount of the polyurethane coating is 8 to 20 g / m 2 ; The curing temperature is 150~300℃; The time is 1~5h.

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