A high-strength colorful laser film and its preparation method

Abstract

This application relates to the technical field of colorful laser films, and specifically discloses a high-strength colorful laser film and a preparation method thereof. The laser film comprises the following raw materials in parts by weight: 20-50 parts of chromite micropowder and 100-150 parts of modified nanocrystalline cellulose; the modified nanocrystalline cellulose comprises the following raw materials in parts by weight: 5-10 parts of photoinitiator, 50-80 parts of polyacrylic acid, 75-125 parts of solvent, 100-150 parts of oxidized modified nanocrystalline cellulose, and 35-40 parts of nanoaluminum; the modified nanocrystalline cellulose is obtained by a step of mixing the photoinitiator, polyacrylic acid, solvent, oxidized modified nanocrystalline cellulose and nanoaluminum and then irradiating with ultraviolet light; the oxidized modified nanocrystalline cellulose is obtained by a step of treating nanocrystalline cellulose with hydrogen peroxide. The colorful laser film of this application has the advantages of high tensile strength and good colorful effect.

Description

Technical Field

[0001] The present application relates to the technical field of colorful laser films, and more specifically, it relates to a high-strength colorful laser film and a preparation method thereof. Background Art

[0002] A colorful laser film is a special film that can present colorful laser effects such as rainbows and gratings, with decorative and anti-counterfeiting effects, and is widely used in fields such as packaging technology. In addition to its application in anti-counterfeiting marks, due to its colorful effect, colorful laser films are also widely used in decoration. For example, the ribbons of cakes and the pom-poms of cheerleading teams all require the use of colorful laser films.

[0003] Currently, when preparing laser films, some processes involve mixing laser aluminum paste or metal slurry with ink binder, additives, and solvents, and brushing them on the surfaces of substrates such as plastics and glasses to prepare a film with a colorful laser effect. There are also processes that prepare colorful laser films by alternately placing two different materials of films. It utilizes the principle of continuous reflection and interference of light in different materials to achieve the colorful laser effect, but this method has a complex process and requires the preparation of multiple layers of films. In addition, there is also a related technology that composites two polyamide layers with a colorful metallic texture to obtain a colorful laser film. It utilizes the crystal properties of polyamide, and there are crystalline polyamide and non-crystalline boundary polyamide in the polyamide layer, thereby achieving the laser effect.

[0004] Among them, when using the crystal properties of polymers to prepare the ribbons of cakes and the pom-poms of cheerleading teams, there are problems such as insufficient tensile strength, resulting in the ribbons being easily broken and the pom-poms being easily damaged; in addition, the colorful effects of such laser films are relatively single. Summary of the Invention

[0005] In order to improve the problems of poor tensile strength and single colorful effect of existing colorful laser films, the present application provides a high-strength colorful laser film and a preparation method thereof.

[0006] In the first aspect, the present application provides a high-strength colorful laser film, adopting the following technical solution:

[0007] A high-strength colorful laser film, comprising the following raw materials in parts by weight:

[0008] 20 - 50 parts of chromite fine powder, 5 - 10 parts of silane coupling agent, 100 - 150 parts of modified nanocrystalline cellulose, 5 - 10 parts of film-forming agent, and 75 - 95 parts of water;

[0009] Taking the weight of the modified nanocellulose crystals as a reference, the modified nanocellulose crystals comprise raw materials in the following parts by weight: 5-10 parts of photoinitiator, 50-80 parts of polyacrylic acid, 75-125 parts of solvent, 100-150 parts of oxidatively modified nanocellulose crystals, and 35-40 parts of nanoaluminum;

[0010] The modified nanocellulose crystals are prepared by a method comprising the following steps: mixing the photoinitiator, polyacrylic acid, solvent, oxidatively modified nanocellulose crystals, and nanoaluminum, and then carrying out an ultraviolet irradiation reaction;

[0011] The oxidatively modified nanocellulose crystals are obtained by treating the nanocellulose crystals through a step comprising treatment with a hydrogen peroxide solution.

[0012] Nanocellulose crystals have optical properties due to their liquid crystal properties. According to the crystal form of the liquid crystal, they are divided into smectic, nematic, and cholesteric types. Currently, most of the prepared nanocellulose crystals are cholesteric. The molecules within the cholesteric liquid crystal layer are arranged in parallel, and the long axis orientation directions of the molecules between layers are different. Moreover, between adjacent layers, the orientation of the long axis of the molecules regularly twists by a certain angle according to this rule, and accumulates layer by layer to form a helical structure. Therefore, cholesteric liquid crystals will exhibit beautiful colors under white light irradiation. In this application, after oxidizing the nanocellulose crystals, some of the hydroxyl groups on their molecules are converted into carboxyl groups or aldehyde groups to better adsorb nanoaluminum. In addition, after grafting polyacrylic acid onto the oxidatively modified nanocellulose crystals, their structural stability is more excellent, making the binding stability of the oxidatively modified nanocellulose crystals - nanoaluminum better, and at the same time, more nanoaluminum is loaded on the oxidatively modified nanocellulose crystals. Although the liquid crystal properties of the nanocellulose crystals decrease after oxidation modification and grafting of polyacrylic acid, they still maintain certain liquid crystal properties.

[0013] In terms of strength, even though polyacrylic acid is grafted onto the oxidatively modified nanocellulose crystals, there is still a problem of poor strength. Therefore, nanoaluminum also has the effect of enhancing strength. The nanocellulose crystals in the modified nanocellulose crystals are oxidatively modified, and some of the hydroxyl groups on their molecules are converted into carboxyl groups or aldehyde groups, enabling the modified nanocellulose crystals to be better dispersed and stably bound and adsorbed to chromite fine powder. The chromite fine powder has high strength, so it can significantly improve the mechanical properties of the laser film. In this application, there is a certain particle size grading between nanoaluminum and chromite fine powder. Nanoaluminum is mainly filled within the oxidatively modified nanocellulose crystals - polyacrylic acid, and chromite fine powder is filled between the macroscopic particles of the modified nanocellulose crystals. Therefore, the tensile strength of the colorful laser film can be fully improved.

[0014] The present application achieves a dazzling color effect. On the one hand, it realizes the reflection and transmission of light based on the liquid crystal properties of nanocellulose crystals. On the other hand, it is achieved by the light reflection properties of nanoaluminum. In the solution of the present application, due to the advantage of the small particle size of nanoaluminum, nanoaluminum enters into the oxidized and modified nanofibrils of nanocellulose, and is further coated and stabilized by the network structure formed by polyacrylic acid and oxidized and modified nanocellulose crystals. Nanoaluminum is used to make up for the loss of liquid crystal properties caused by oxidation modification and grafting of oxidized and modified nanocellulose crystals, so as to ensure the excellent dazzling laser effect of the laser film.

[0015] Compared with nanocellulose crystals and nanoaluminum, chromite fine powder has poor metallic properties. Therefore, when achieving the improvement of tensile strength, the addition amount of chromite fine powder should not be too high, otherwise it will affect the dazzling color characteristics of the dazzling laser film.

[0016] Optionally, the oxidized and modified nanocellulose crystals are prepared by a method including the following steps: dispersing nanocellulose crystals into a hydrogen peroxide solution and stirring for reaction, and then washing with water and drying to obtain oxidized and modified nanocellulose crystals; the dosage ratio of the nanocellulose crystals to the hydrogen peroxide solution is 0.08 - 0.15 g of nanocellulose crystals / ml of hydrogen peroxide solution.

[0017] By adopting the above technical solution, the above method efficiently and effectively oxidizes nanocellulose crystals, realizes the conversion of some hydroxyl groups on the nanocellulose crystals into carboxyl groups or aldehyde groups, thereby improving its adsorption characteristics and ensuring the binding stability with nanoaluminum.

[0018] Further optionally, the hydrogen peroxide content in the hydrogen peroxide solution is 25 - 50 wt%.

[0019] Optionally, after dispersing the nanocellulose crystals into hydrogen peroxide, the stirring time is 5 - 10 min.

[0020] By adopting the above technical solution, the required oxidized and modified nanocellulose whiskers are obtained with the above stirring time: when the stirring time is too short, the oxidation degree of the nanocellulose crystals is too low, which will affect its adsorption effect on nanoaluminum, resulting in less nanoaluminum loaded on the modified nanocellulose crystals, and thus the dazzling color effect of the dazzling laser film is poor; when the stirring time is too long, the nanocellulose crystals are over-oxidized, affecting the liquid crystal properties of the nanocellulose crystals, and thus affecting the dazzling color effect of the dazzling laser film.

[0021] Optionally, when preparing the modified nanocellulose crystals, the ultraviolet irradiation time is 2 - 8 min, and the temperature during ultraviolet irradiation is 10 - 30 °C.

[0022] By adopting the above technical solutions, nano-crystalline cellulose and polyacrylic acid can be stably cross-linked and cured to better load and stabilize nano-aluminum, and then a modified nano-crystalline cellulose with a stable structure is formed.

[0023] Optionally, when preparing the modified nano-crystalline cellulose, the ultraviolet light intensity is 20 - 90 mw / cm 2 .

[0024] Optionally, the width of the nano-crystalline cellulose is 5 - 50 nm, and the length is 50 - 500 nm; the particle size of the nano-aluminum is 20 - 80 nm.

[0025] By adopting the above technical solutions, due to the particle size advantage of nano-aluminum, it has a relatively high specific surface area and surface energy. Therefore, nano-aluminum is easily dispersed on the nano-crystalline cellulose, and the combination of the two is stable.

[0026] Optionally, the particle size of the chromite fine powder is 30 - 50 μm.

[0027] Further optionally, the Mohs hardness of the chromite fine powder is 5.2 - 5.8; the content of Cr2O3 in the chromite fine powder is 25 - 40 wt%.

[0028] Optionally, the solvent is selected from one or more of water, isopropanol, and ethanol.

[0029] Optionally, the film-forming agent is selected from any one or more of acrylic resin film-forming agents, butadiene resin film-forming agents, polyurethane film-forming agents, and nitrocellulose film-forming agents.

[0030] In a second aspect, the present application provides a method for preparing a high-strength colorful laser film, adopting the following technical solutions:

[0031] A method for preparing a high-strength colorful laser film, the preparation method comprising the following steps:

[0032] Mix all the modified nano-crystalline cellulose, chromite fine powder, silane coupling agent, film-forming agent, and water evenly according to the ratio, and then press into shape and dry to obtain the high-strength colorful laser film.

[0033] Optionally, the pressure during pressing into shape is 8 - 15 kgf / cm 2 .

[0034] By adopting the above technical solutions, when pressing into shape with the above pressure, a colorful laser film with an appropriate thickness is obtained.

[0035] In summary, the present application has the following beneficial effects:

[0036] 1. The nanocellulose crystals and nanoaluminum in the present application endow the colorful laser film with a colorful laser effect; the nanoaluminum and chromite micropowder ensure a certain tensile strength of the colorful laser film; when the nanocellulose crystals, nanoaluminum and chromite micropowder are compounded together, in order to make the three stably combine and exert corresponding effects, oxidized modified nanocellulose crystals are first selected to improve their adsorption characteristics. Secondly, polyacrylic acid is grafted onto the oxidized modified nanocellulose crystals, and the network structure formed by the oxidized modified nanocellulose crystals and polyacrylic acid is also conducive to improving the adsorption and binding stability of the modified nanocellulose crystals to nanoaluminum and chromite micropowder.

[0037] 2. The width of the modified nanocellulose crystals in the present application is 5 - 50 nm, the length is 50 - 500 nm, the particle size of the nanoaluminum is 20 - 80 nm, and the particle size of the chromite micropowder is 30 - 50 μm. There are differences in the sizes of these three raw materials. The surface energy brought by the tiny particle size of the nanoaluminum enables it to be easily and stably loaded on the oxidized modified nanocellulose crystals; at the same time, the relatively large-particle chromite micropowder can significantly improve the tensile strength of the laser film, and the particle size is appropriate, so there will be no problem of sedimentation and aggregation of the chromite micropowder due to uneven dispersion.

[0038] 3. The colorful laser film is prepared by a pressing method in the present application. This method does not require heating and causes little thermal damage to the colorful laser film; under a pressure of 8 - 15 kgf / cm 2 a colorful laser film with a thickness of 15 - 35 μm is obtained. Detailed Embodiment

[0039] The present application will be further described in detail below with reference to the embodiments.

[0040] Unless otherwise specified, the raw materials involved in the present application are all commercially available.

[0041] Preparation Example of Modified Nanocellulose Crystals

[0042] The following preparation examples are only the implementation methods for preparing modified nanocellulose crystals. When the specific dosage of the modified nanocellulose crystals exceeds the amount of the prepared modified nanocellulose crystals, the required amount of the modified nanocellulose crystals in the embodiments can be obtained by preparing multiple times, or the amounts of each raw material can be enlarged in equal proportion to obtain the required amount of the modified nanocellulose crystals in the embodiments.

[0043] Preparation Example 1

[0044] Raw materials and their ratios for preparing modified nanocellulose crystals: 5 g of photoinitiator Darocur 2959, 50 g of polyacrylic acid, 75 g of water, 100 g of oxidatively modified nanocellulose crystals, and 35 g of nanoaluminum. Among them, polyacrylic acid is also known as acrylic resin and carbomer, and its CAS number is 9003-01-4; the purity of nanoaluminum is 99 wt%, and the particle size of nanoaluminum is 20 - 80 nm.

[0045] Preparation method of oxidatively modified nanocellulose crystals: Dispersed nanocellulose crystals into hydrogen peroxide solution at a ratio of 0.08 g of nanocellulose crystals / ml of hydrogen peroxide solution and stirred for reaction for 5 min. The hydrogen peroxide content in the hydrogen peroxide solution is 50 wt%; then washed with water three times, filtered, and the solid was dried to obtain oxidatively modified nanocellulose crystals. Among them, the CAS number of nanocellulose crystals is 9004-34-6, the width of nanocellulose crystals is 5 - 50 nm, and the length is 50 - 500 nm.

[0046] Preparation method of modified nanocellulose crystals: Mix the above-mentioned amounts of photoinitiator Darocur 2959, polyacrylic acid, water, oxidatively modified nanocellulose crystals, and nanoaluminum evenly, and then under the conditions of ultraviolet light intensity of 20 mw / cm 2 and temperature of 30 °C, irradiate with ultraviolet light for 8 min, then filter, wash the solid with water and filter and dry to obtain modified nanocellulose crystals.

[0047] Preparation Example 2

[0048] Raw materials and their ratios for preparing modified nanocellulose crystals: 7.5 g of photoinitiator Darocur 2959, 65 g of polyacrylic acid, 100 g of isopropanol, 135 g of oxidatively modified nanocellulose crystals, and 38 g of nanoaluminum. Among them, polyacrylic acid and nanoaluminum are the same as in Preparation Example 1.

[0049] Preparation method of oxidatively modified nanocellulose crystals: Dispersed nanocellulose crystals into hydrogen peroxide solution at a ratio of 0.12 g of nanocellulose crystals / ml of hydrogen peroxide solution and stirred for reaction for 7.5 min. The hydrogen peroxide content in the hydrogen peroxide solution is 28 wt%; then washed with water three times, filtered, and the solid was dried to obtain oxidatively modified nanocellulose crystals. The nanocellulose crystals therein are the same as in Preparation Example 1.

[0050] Preparation method of modified nanocellulose crystals: Mix the above-mentioned amounts of photoinitiator Darocur 2959, polyacrylic acid, water, oxidatively modified nanocellulose crystals, and nanoaluminum evenly, and then under the conditions of ultraviolet light intensity of 75 mw / cm 2、Under the condition that the temperature is 25 °C, irradiate with ultraviolet light for 5 min, then filter. Wash the solid with water and then filter and dry to obtain modified nanocrystalline cellulose.

[0051] Preparation Example 3

[0052] Raw materials and their ratios for preparing modified nanocrystalline cellulose: 10 g of photoinitiator Darocur 2959, 80 g of polyacrylic acid, 125 g of ethanol, 150 g of oxidized modified nanocrystalline cellulose, and 40 g of nano-aluminum. Among them, the polyacrylic acid and nano-aluminum are the same as those in Preparation Example 1.

[0053] Preparation method of oxidized modified nanocrystalline cellulose: Dispersed nanocrystalline cellulose into hydrogen peroxide solution at a ratio of 0.15 g of nanocrystalline cellulose / ml of hydrogen peroxide solution and stirred for 10 min. The hydrogen peroxide content in the hydrogen peroxide solution is 25 wt%. Then wash three times with water, filter and dry the solid to obtain oxidized modified nanocrystalline cellulose. The nanocrystalline cellulose therein is the same as that in Preparation Example 1.

[0054] Preparation method of modified nanocrystalline cellulose: Mix the above-mentioned amounts of photoinitiator Darocur 2959, polyacrylic acid, water, oxidized modified nanocrystalline cellulose, and nano-aluminum evenly, and then under the condition of ultraviolet light intensity of 90 mw / cm 2 、Irradiate with ultraviolet light for 2 min under the condition that the temperature is 10 °C, then filter. Wash the solid with water and then filter and dry to obtain modified nanocrystalline cellulose.

[0055] Preparation Example 4

[0056] The difference between this preparation example and Preparation Example 2 is that when preparing modified nanocrystalline cellulose, nanocrystalline cellulose of equal weight is used to replace oxidized modified nanocrystalline cellulose, and the others are the same as Preparation Example 2.

[0057] Preparation Example 5

[0058] The difference between this preparation example and Preparation Example 2 is that when preparing modified nanocrystalline cellulose, the preparation raw materials do not contain nano-aluminum. The specific raw materials and their ratios for preparing modified nanocrystalline cellulose are: 7.5 g of photoinitiator Darocur 2959, 65 g of polyacrylic acid, 100 g of isopropanol, and 135 g of oxidized modified nanocrystalline cellulose.

[0059] Preparation Example 6

[0060] The difference between Preparation Example 0 and Preparation 2 lies in the different addition amounts of nano-aluminum when preparing the modified nano-cellulose crystals. The specific raw materials and their ratios for preparing the modified nano-cellulose crystals are as follows: photoinitiator Darocur 2959, 7.5 g; polyacrylic acid, 65 g; isopropanol, 100 g; oxidized modified nano-cellulose crystals, 135 g; nano-aluminum, 30 g.

[0061] Preparation Example 7

[0062] The difference between Preparation Example 6 and Preparation 2 lies in the different addition amounts of nano-aluminum when preparing the modified nano-cellulose crystals. The specific raw materials and their ratios for preparing the modified nano-cellulose crystals are as follows: photoinitiator Darocur 2959, 7.5 g; polyacrylic acid, 65 g; isopropanol, 100 g; oxidized modified nano-cellulose crystals, 135 g; nano-aluminum, 35 g.

[0063] Preparation Example 8

[0064] The difference between Preparation Example 12 and Preparation 2 lies in the different addition amounts of nano-aluminum when preparing the modified nano-cellulose crystals. The specific raw materials and their ratios for preparing the modified nano-cellulose crystals are as follows: photoinitiator Darocur 2959, 7.5 g; polyacrylic acid, 65 g; isopropanol, 100 g; oxidized modified nano-cellulose crystals, 135 g; nano-aluminum, 40 g.

[0065] Preparation Example 9

[0066] The difference between Preparation Example 18 and Preparation 2 lies in the different addition amounts of nano-aluminum when preparing the modified nano-cellulose crystals. The specific raw materials and their ratios for preparing the modified nano-cellulose crystals are as follows: photoinitiator Darocur 2959, 7.5 g; polyacrylic acid, 65 g; isopropanol, 100 g; oxidized modified nano-cellulose crystals, 135 g; nano-aluminum, 45 g.

[0067] Preparation Example 10

[0068] The difference between Preparation Example 24 and Preparation 2 lies in the different addition amounts of oxidized modified nano-cellulose crystals when preparing the modified nano-cellulose crystals. The specific raw materials and their ratios for preparing the modified nano-cellulose crystals are as follows: photoinitiator Darocur 2959, 7.5 g; polyacrylic acid, 65 g; isopropanol, 100 g; oxidized modified nano-cellulose crystals, 90 g; nano-aluminum, 38 g.

[0069] Preparation Example 11

[0070] The difference between this Preparation Example and Preparation 2 lies in the different addition amounts of oxidized modified nanocellulose crystals when preparing modified nanocellulose crystals. The specific raw materials and their ratios for preparing modified nanocellulose crystals are as follows: photoinitiator Darocur 2959, 7.5 g; polyacrylic acid, 65 g; isopropanol, 100 g; oxidized modified nanocellulose crystals, 100 g; nanoaluminum, 38 g.

[0071] Preparation Example 12

[0072] The difference between this Preparation Example and Preparation 2 lies in the different addition amounts of oxidized modified nanocellulose crystals when preparing modified nanocellulose crystals. The specific raw materials and their ratios for preparing modified nanocellulose crystals are as follows: photoinitiator Darocur 2959, 7.5 g; polyacrylic acid, 65 g; isopropanol, 100 g; oxidized modified nanocellulose crystals, 150 g; nanoaluminum, 38 g.

[0073] Preparation Example 13

[0074] The difference between this Preparation Example and Preparation 2 lies in the different addition amounts of oxidized modified nanocellulose crystals when preparing modified nanocellulose crystals. The specific raw materials and their ratios for preparing modified nanocellulose crystals are as follows: photoinitiator Darocur 2959, 7.5 g; polyacrylic acid, 65 g; isopropanol, 100 g; oxidized modified nanocellulose crystals, 160 g; nanoaluminum, 38 g.

[0075] Preparation Example 14

[0076] The difference between this Preparation Example and Preparation 2 lies in that when preparing oxidized modified nanocellulose crystals, the dosage ratio of nanocellulose crystals to hydrogen peroxide solution is 0.04 g of nanocellulose crystals / ml of hydrogen peroxide solution.

[0077] Preparation Example 15

[0078] The difference between this Preparation Example and Preparation 2 lies in that when preparing oxidized modified nanocellulose crystals, the dosage ratio of nanocellulose crystals to hydrogen peroxide solution is 0.19 g of nanocellulose crystals / ml of hydrogen peroxide solution.

[0079] Example

[0080] Example 1

[0081] Raw materials and their ratios for preparing high-strength colorful laser film: 20 g of chromite micropowder, 5 g of silane coupling agent KH-550, 100 g of modified nanocellulose crystals, 5 g of acrylic resin film-forming agent CAP-800, and 75 g of water. Among them, the modified nanocellulose crystals are prepared according to Preparation Example 1 of modified nanocellulose crystals; the chromite micropowder is purchased from Duyixin Friction Powder Co., Ltd., Daye City, with a Mohs hardness of 5.5, a Cr2O3 content of about 35 wt%, and a particle size of 30-50 μm.

[0082] Method for preparing high-strength colorful laser film: Mix all the modified nanocellulose crystals, chromite micropowder, silane coupling agent KH-550, acrylic resin film-forming agent CAP-800, and water evenly according to the ratio, and then press and form at a pressure of 8 kgf / cm 2 and dry to obtain a colorful laser film with a thickness of about 35 μm, namely, a high-strength colorful laser film.

[0083] Example 2

[0084] Raw materials and their ratios for preparing high-strength colorful laser film: 35 g of chromite micropowder, 7.5 g of silane coupling agent KH-550, 135 g of modified nanocellulose crystals, 7.5 g of acrylic resin film-forming agent CAP-800, and 85 g of water. Among them, the modified nanocellulose crystals are prepared according to Preparation Example 2 of modified nanocellulose crystals; the chromite micropowder is the same as in Example 1.

[0085] Method for preparing high-strength colorful laser film: Mix all the modified nanocellulose crystals, chromite micropowder, silane coupling agent KH-550, acrylic resin film-forming agent CAP-800, and water evenly according to the ratio, and then press and form at a pressure of 12 kgf / cm 2 and dry to obtain a colorful laser film with a thickness of about 18 μm, namely, a high-strength colorful laser film.

[0086] Example 3

[0087] Raw materials and their ratios for preparing high-strength colorful laser film: 50 g of chromite micropowder, 10 g of silane coupling agent KH-550, 150 g of modified nanocellulose crystals, 10 g of acrylic resin film-forming agent CAP-800, and 95 g of water. Among them, the modified nanocellulose crystals are prepared according to Preparation Example 3 of modified nanocellulose crystals; the chromite micropowder is the same as in Example 1.

[0088] Method for preparing high-strength colorful laser film: Mix all the modified nanocellulose crystals, chromite micropowder, silane coupling agent KH-550, acrylic resin film-forming agent CAP-800, and water evenly according to the ratio, and then press and form at a pressure of 15 kgf / cm 2It is pressed and dried under pressure to obtain a high-strength colorful laser film with a thickness of about 15 μm, namely, a high-strength colorful laser film.

[0089] Example 4

[0090] The difference between this example and Example 2 is that the modified nanocrystalline cellulose used to prepare the high-strength colorful laser film is prepared according to Preparation Example 7 of modified nanocrystalline cellulose, and the others are the same as in Example 2.

[0091] Example 5

[0092] The difference between this example and Example 2 is that the modified nanocrystalline cellulose used to prepare the high-strength colorful laser film is prepared according to Preparation Example 8 of modified nanocrystalline cellulose, and the others are the same as in Example 2.

[0093] Example 6

[0094] The difference between this example and Example 2 is that the modified nanocrystalline cellulose used to prepare the high-strength colorful laser film is prepared according to Preparation Example 11 of modified nanocrystalline cellulose, and the others are the same as in Example 2.

[0095] Example 7

[0096] The difference between this example and Example 2 is that the modified nanocrystalline cellulose used to prepare the high-strength colorful laser film is prepared according to Preparation Example 12 of modified nanocrystalline cellulose, and the others are the same as in Example 2.

[0097] Example 8

[0098] The difference between this example and Example 2 is that the modified nanocrystalline cellulose used to prepare the high-strength colorful laser film is prepared according to Preparation Example 14 of modified nanocrystalline cellulose, and the others are the same as in Example 2.

[0099] Example 9

[0100] The difference between this example and Example 2 is that the modified nanocrystalline cellulose used to prepare the high-strength colorful laser film is prepared according to Preparation Example 15 of modified nanocrystalline cellulose, and the others are the same as in Example 2.

[0101] Comparative Example

[0102] Comparative Example 1

[0103] The difference between this comparative example and Example 2 is that the modified nanocrystalline cellulose used to prepare the high-strength colorful laser film is prepared according to Preparation Example 4 of modified nanocrystalline cellulose, and the others are the same as in Example 2.

[0104] Comparative Example 2

[0105] The difference between this comparative example and Example 2 is that the modified nanocellulose crystals used to prepare the high-strength colorful laser film are prepared from Modified Nanocellulose Crystal Preparation Example 5, and the others are the same as Example 2.

[0106] Comparative Example 3

[0107] The difference between this comparative example and Example 2 is that the modified nanocellulose crystals used to prepare the high-strength colorful laser film are prepared from Modified Nanocellulose Crystal Preparation Example 6, and the others are the same as Example 2.

[0108] Comparative Example 4

[0109] The difference between this comparative example and Example 2 is that the modified nanocellulose crystals used to prepare the high-strength colorful laser film are prepared from Modified Nanocellulose Crystal Preparation Example 9, and the others are the same as Example 2.

[0110] Comparative Example 5

[0111] The difference between this comparative example and Example 2 is that the modified nanocellulose crystals used to prepare the high-strength colorful laser film are prepared from Modified Nanocellulose Crystal Preparation Example 10, and the others are the same as Example 2.

[0112] Comparative Example 6

[0113] The difference between this comparative example and Example 2 is that the modified nanocellulose crystals used to prepare the high-strength colorful laser film are prepared from Modified Nanocellulose Crystal Preparation Example 13, and the others are the same as Example 2.

[0114] Comparative Example 7

[0115] The difference between this comparative example and Example 2 is that the raw materials used to prepare the high-strength colorful laser film do not contain chromite fine powder, and the others are the same as Example 2.

[0116] Comparative Example 8

[0117] The difference between this comparative example and Example 2 is that the modified nanocellulose crystals are replaced with an equal weight of nanocellulose crystals, and the others are the same as Example 2.

[0118] Performance Detection Test

[0119] 1. Perform performance detection on the prepared colorful laser film. Among them, the tensile strength is detected according to the relevant regulations of GB / T 1040.3-2006. The colorful metallic texture effect is determined by the visual method: select quality inspectors with the ability to judge in this field for visual observation and make evaluation results of *, **, or *** respectively. Among them, '*' means no colorful effect or poor colorful effect; '**' means there is an obvious three-primary-color colorful effect visible to the naked eye; '***' means there is an obvious multiple three-primary-color colorful effect visible to the naked eye. The specific detection results are shown in Table 1.

[0120] Table 1 Tensile properties and color-changing effects of different color-changing laser films

[0121]

[0122]

[0123] As can be seen from the data results in Table 1, the color-changing laser film obtained in this application has excellent tensile properties and color-changing effects. Specifically, however, the transverse tensile strength of the color-changing laser film is better than the longitudinal tensile strength, which may be related to the distribution direction of nanocellulose crystals: nanocellulose crystals tend to be distributed along the horizontal direction of the color-changing laser film, making the adsorbed nano-aluminum and chromite micropowders also more distributed in the horizontal direction of the color-changing laser film. Therefore, the transverse tensile strength of the color-changing laser film is better than the longitudinal tensile strength.

[0124] By comparing the data results of Example 2, Examples 4-5, and Comparative Examples 3-4, it can be seen that when preparing modified nanocellulose crystals, the amount of loaded nano-aluminum is recommended to be within 35-40 parts (such as Example 2, Examples 4-5). Beyond this range (such as Comparative Examples 3-4), the tensile strength and color-changing effects of the color-changing laser film will be significantly reduced. This may be because too little addition of nano-aluminum (such as Comparative Example 3) results in too little nano-aluminum loaded on the nanocellulose crystals, which will directly affect the tensile strength of the color-changing laser film; and the color-changing effect of the color-changing laser film is mainly achieved by nano-aluminum and nanocellulose crystals. When the amount of nano-aluminum is too small, in the case of adding chromite micropowders, the metal properties of the chromite micropowders are poor, which will significantly affect the optical properties of the nanocellulose crystals, and a small amount of nano-aluminum is not enough to make up for this loss, resulting in a significant reduction in the color-changing effect of the color-changing laser film. Too much addition of nano-aluminum (such as Comparative Example 4) will directly affect the actual loading amount and loading stability of nano-aluminum, and thus will still affect the tensile strength of the color-changing laser film; however, the color-changing effect of the color-changing laser film in Comparative Example 4 is relatively excellent.

[0125] By comparing the data results of Example 2, Examples 6-7 and Comparative Examples 5-6, it is reflected that when preparing modified nanocrystalline cellulose, the addition amount of oxidized modified nanocrystalline cellulose is recommended to be in the range of 100-150 parts (such as Example 2, Examples 6-7). Beyond this range (such as Comparative Examples 5-6), the tensile strength of the colorful laser film will be significantly reduced. In addition, the colorful effect of the colorful laser film is relatively single. This may be because too little addition amount of oxidized modified nanocrystalline cellulose (such as Comparative Example 5) will directly affect the actual loading amount and loading stability of nanoaluminum, thereby affecting the tensile strength of the colorful laser film; in addition, this will also directly lead to poor colorful effect of the colorful laser film. If the addition amount of oxidized modified nanocrystalline cellulose is too much (such as Comparative Example 6), the amount of nanoaluminum loaded on the nanocrystalline cellulose is relatively small, and the strengthening effect of nanoaluminum is not obvious, thereby affecting the tensile strength of the colorful laser film; however, overall, the colorful effect of the colorful laser film is relatively excellent.

[0126] By comparing the data of Example 2, Examples 8-9 and Comparative Example 1, it can be seen that when the nanocrystalline cellulose is oxidized, the degree of oxidation will also have a certain impact on the tensile strength of the colorful laser film: when the relative amount of the oxidant hydrogen peroxide solution is small (such as Example 8), the number of hydroxyl groups converted into carboxyl or aldehyde groups on the nanocrystalline cellulose is small, resulting in insufficient adsorption amount and / or poor adsorption stability of the oxidized modified nanocrystalline cellulose to nanoaluminum and chromite fine powder, thereby affecting the tensile strength and colorful effect of the colorful laser film. When the relative amount of the oxidant hydrogen peroxide solution is large (such as Example 9), the number of hydroxyl groups converted into carboxyl or aldehyde groups on the nanocrystalline cellulose is too much, which will still lead to poor adsorption stability of the oxidized modified nanocrystalline cellulose to nanoaluminum and chromite fine powder, and ultimately will still affect the tensile strength and colorful effect of the colorful laser film. However, when the nanocrystalline cellulose in Comparative Example 1 is not oxidized and modified, it will have a greater impact on its adsorption characteristics, resulting in a significant reduction in the tensile strength and colorful effect of the colorful laser film when directly using nanocrystalline cellulose to load nanoaluminum and chromite fine powder to prepare the colorful laser film.

[0127] In addition, the results of both Comparative Example 2 and Comparative Example 8 consistently reflect the importance of loading nanoaluminum in ensuring the tensile strength and colorful effect of the colorful laser film. Through the results of Comparative Example 7, it is found that the addition of chromite fine powder has the greatest impact on the tensile strength of the colorful laser film. When preparing the colorful laser film without adding chromite fine powder, the tensile strength of the prepared colorful laser film is the worst; however, the colorful effect of the colorful laser film is excellent, and it can still present a variety of three-primary-color colorful effects.

[0128] 2. The glossiness of the prepared colorful laser film was detected, specifically referring to the relevant regulations of GB / T 8807-1988 for detection.

[0129] The glossiness of the colorful laser films prepared in Example 2, Comparative Example 2, Comparative Example 7 and Comparative Example 8 of the present application are 90%, 80%, 92% and 80% respectively. From the results of Example 2 and Comparative Example 7, it can be seen that although chromite micropowder is added when preparing the colorful laser film in the present application, which will have a certain impact on the glossiness of the colorful laser film, overall, the colorful laser film still has relatively excellent glossiness. In addition, the results of Comparative Example 2 and Comparative Example 8 both consistently show that the addition of nano-aluminum significantly improves the glossiness of the colorful laser film.

[0130] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications without creative contributions to this embodiment as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A high-strength colorful laser film, characterized in that, It comprises the following raw materials in parts by weight: 20 - 50 parts of chromite fine powder, 5 - 10 parts of silane coupling agent, 100 - 150 parts of modified nanocellulose crystals, 5 - 10 parts of film-forming agent, 75 - 95 parts of water; Taking the weight of the modified nanocellulose crystals as a reference, the modified nanocellulose crystals comprise the following raw materials in parts by weight: 5 - 10 parts of photoinitiator, 50 - 80 parts of polyacrylic acid, 75 - 125 parts of solvent, 100 - 150 parts of oxidized modified nanocellulose crystals, 35 - 40 parts of nano-aluminum; The modified nanocellulose crystals are prepared by a method comprising the following steps: mixing the photoinitiator, polyacrylic acid, solvent, oxidized modified nanocellulose crystals and nano-aluminum, and then obtaining the product through ultraviolet irradiation reaction; The oxidized modified nanocellulose crystals are obtained by treating nanocellulose crystals through a step comprising treatment with hydrogen peroxide solution; Among them, the width of the modified nanocellulose crystals is 5 - 50 nm, the length is 50 - 500 nm, the particle size of nano-aluminum is 20 - 80 nm, and the particle size of chromite fine powder is 30 - 50 μm.

2. The colorful laser film according to claim 1, characterized in that, The oxidized modified nanocellulose crystals are prepared by a method comprising the following steps: dispersing nanocellulose crystals into hydrogen peroxide solution and stirring for reaction, then washing with water and drying to obtain oxidized modified nanocellulose crystals; the dosage ratio of the nanocellulose crystals to the hydrogen peroxide solution is 0.08 - 0.15 g of nanocellulose crystals / ml of hydrogen peroxide solution.

3. The colorful laser film according to claim 2, characterized in that, After dispersing the nanocellulose crystals into hydrogen peroxide solution, the stirring time is 5 - 10 min.

4. The colorful laser film according to claim 1, wherein When preparing the modified nanocellulose crystals, the ultraviolet irradiation time is 2 - 8 min, and the temperature during ultraviolet irradiation is 10 - 30 °C.

5. The colorful laser film according to claim 1, wherein When preparing the modified nanocrystalline cellulose, the ultraviolet light intensity is 20-90 mw / cm 2 .

6. The colorful laser film according to claim 1, characterized in that, The film-forming agent is selected from any one or more of acrylic resin film-forming agent, butadiene resin film-forming agent, polyurethane film-forming agent and nitrocellulose film-forming agent.

7. A method for preparing the high-strength colorful laser film according to any one of claims 1-6, characterized in that, The preparation method comprises the following steps: Mix all the modified nanocellulose crystals, chromite fine powder, silane coupling agent, film-forming agent and water evenly according to the ratio, then press into shape and dry to obtain the high-strength colorful laser film.

8. The preparation method of the high-strength colorful laser film according to claim 7, wherein The pressure during pressing forming is 8 - 15 kgf / cm 2 .

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