阅读说明：本技术 一种提升pet食品包装喷墨涂层紫外性能的纳米材料的制备方法 (Preparation method of nano material for improving ultraviolet performance of PET food packaging ink-jet coating ) 是由 刘丽 丁磊 陈一帆 杜韫哲 钟正祥 黄玉东 于 2019-10-16 设计创作，主要内容包括：本发明公开了一种提升PET食品包装喷墨涂层紫外性能的纳米材料的制备方法,所述方法包括如下步骤：步骤一、二氧化硅包覆氧化锌ZnO@SiO<Sub>2</Sub>的制备；步骤二、颜料ZnO@SiO<Sub>2</Sub>的分散液的制备；步骤三、喷墨涂层涂布液的制备与涂布。本发明以量子点ZnO为核,SiO<Sub>2</Sub>为壳,制备得到一种耐UV-A紫外光纳米粒子,并以其为颜料,PET薄膜为基材,聚乙烯醇为胶粘剂,得到一种具有优异的耐紫外性能、良好的喷墨性能、可以屏蔽大部分UV-A紫外光的PET食品包装薄膜。本发明制备得到的ZnO@SiO<Sub>2</Sub>纳米粒子相比于商用的SiO<Sub>2</Sub>具有较高的孔隙率,这就大大提高了涂层的吸墨性能。(The invention discloses a preparation method of a nano material for improving ultraviolet performance of an ink-jet coating of PET food packaging, which comprises the following steps: step one, coating zinc oxide ZnO @ SiO with silicon dioxide 2 Preparing; step two, pigment ZnO @ SiO 2 Preparing the dispersion of (4); step three, preparing and coating the ink-jet coating liquid. The invention takes quantum dot ZnO as a core and SiO 2 The shell is used for preparing UV-A ultraviolet resistant nano particles, and the UV-A ultraviolet resistant nano particles are used as pigments, PET films are used as base materials, and polyvinyl alcohol is used as an adhesive, so that the UV-A ultraviolet resistant nano particles with excellent performance are obtainedThe PET food packaging film has different ultraviolet resistance, good ink spraying performance and can shield most of UV-A ultraviolet light. ZnO @ SiO prepared by the invention 2 Nanoparticles compared to commercial SiO 2 Has higher porosity, thus greatly improving the ink absorption performance of the coating.)

1. A preparation method of a nano material for improving the ultraviolet performance of an ink-jet coating of PET food packaging is characterized by comprising the following steps:

step one, coating zinc oxide ZnO @ SiO with silicon dioxide₂The preparation of (1):

(1) adding tetraethoxysilane into the stirring quantum dot zinc oxide solution according to the molar ratio of Zn atoms to Si atoms of 1:1 ~ 3, and then adding water into the stirring quantum dot zinc oxide solution according to the molar ratio of tetraethoxysilane to water of 1:4 ~ 8;

(2) stirring for 24 ~ 30h until a precipitate is generated;

(3) carrying out centrifugal washing treatment on the product, collecting the product, and carrying out freeze drying;

step two, pigment ZnO @ SiO₂Preparation of the dispersion of (4):

the ZnO @ SiO obtained in the step one₂Dispersing in water, and performing high-speed dispersion treatment on the water by using a homogenizing emulsifying machine to obtain uniformly dispersed dispersion liquid;

step three, preparing and coating the ink-jet coating liquid:

(1) taking 10 ~ 30 parts of PVA solution and 10 parts of pigment Zn according to parts by [email protected]₂70 ~ 90 parts of the dispersion liquid, 1 ~ 5 parts of boric acid and 5 ~ 10 parts of ethanol are mixed and dispersed at high speed under a homogenizing and emulsifying machine to obtain an evenly dispersed ink-jet coating liquid;

(2) and (3) taking the PET film with a clean surface, coating the ink-jet coating liquid by using a coating machine, and drying to obtain the PET film with the ink-jet coating.

2. The preparation method of the nano material for improving the ultraviolet performance of the ink-jet coating of the PET food packaging according to claim 1, characterized in that the preparation method of the quantum dot zinc oxide solution is as follows:

(1) dissolving anhydrous zinc acetate: taking 1 mol of Zn (Ac)₂Dispersing the mixture into 30 ~ 50mL of absolute ethyl alcohol, gradually heating to 75 ~ 80 ℃, and dispersing and dissolving for 2 ~ 3 h;

(2) dissolving sodium hydroxide, namely taking 1 ~ 3 mol of NaOH, dispersing the NaOH in 10 ~ 30mL of absolute ethyl alcohol, and carrying out ultrasonic treatment for 10 ~ 20min until the NaOH is dissolved;

(3) reacting Zn (Ac) in the step (1)₂And (3) mixing the solution with the NaOH solution in the step (2) according to the molar ratio of 1:1 ~ 3, placing the mixture at room temperature for stirring, and reacting for 1.5 ~ 3 h.

3. The preparation method of the nano material for improving the ultraviolet performance of the ink-jet coating of the PET food packaging according to claim 2, wherein the ultrasonic power is 480W, and the ultrasonic time is 10 ~ 20 min.

4. The method for preparing nano material for improving the ultraviolet performance of the ink-jet coating of the PET food package according to claim 1, wherein the rotation speed of the centrifugal washing is 9000 ~ 10000rmp/min, the times are 3 ~ 4 times, and each time is 10 min.

5. The method for preparing nano material for improving the ultraviolet performance of the ink-jet coating of the PET food packaging according to claim 1, wherein the mass concentration of the PVA solution is 2 ~ 20%.

6. The method for preparing nano material for improving the ultraviolet performance of the ink-jet coating of the PET food packaging according to claim 1, wherein the high-speed dispersion time is 40 ~ 50 min.

7. The method for preparing nano material for improving the ultraviolet performance of the ink-jet coating of the PET food packaging according to claim 1, wherein the drying temperature is 75 ~ 90 ℃.

Technical Field

The invention relates to a preparation method of a PET food packaging ink-jet coating nano material resistant to UV-A ultraviolet light.

Background

Ultraviolet radiation is radiation from the sun, the wavelength range of which is 200 ~ 400nm, wherein the high-energy short wave energy below 290 nm is almost completely absorbed by the atmosphere, and the wavelength of the ultraviolet radiation finally reaching the ground is about 290 ~ 400nm, wherein the ultraviolet radiation of 290 ~ 320 nm only accounts for 8 percent of the total ultraviolet radiation reaching the ground, and most of the ultraviolet radiation is ultraviolet radiation in the UV-A (320 ~ 400 nm) wave band.

Various transparent PET food packaging bags used in daily life are not qualified, and are directly irradiated by ultraviolet rays, so that food is deteriorated and seriously harms human health, and the transmittance of the transparent PET food packaging bags to the ultraviolet rays directly influences the human health. In order to solve the problem, various ultraviolet shielding agents appear in the modern society, the ultraviolet shielding problem becomes a topic which is objected to in the contemporary scientific community, and the ultraviolet shielding agents have wide application prospects.

At present, ultraviolet screening agents are mainly divided into organic screening agents and inorganic screening agents. The shielding performance of the organic shielding agent is gradually reduced along with the irradiation of ultraviolet light and has strong toxicity, which can substantially affect the ultraviolet shielding performance of the film. Inorganic ultraviolet shielding agents such as titanium dioxide, zinc oxide and the like have excellent ultraviolet shielding performance, but the phenomenon of photocatalytic degradation can occur, so that the performance of a packaging coating is reduced, and particularly, after long-time illumination, character images printed by ink jet on the surface of a packaging film become fuzzy, so that the application of a packaging material is influenced. And these inorganic uv screeners do not have the ink receptivity required for inkjet printing, further limiting the application of the material.

Disclosure of Invention

In order to solve the problems of poor UV-A ultraviolet resistance and poor ink-jet printing performance of the conventional transparent PET food packaging film, the invention provides a preparation method of a nano material for improving the ultraviolet performance of an ink-jet coating of PET food packaging. The invention takes quantum dot ZnO as a core and SiO₂The PET food packaging film has excellent ultraviolet resistance, good ink spraying performance and can shield most of UV-A ultraviolet light.

The purpose of the invention is realized by the following technical scheme:

a preparation method of a nano material for improving the ultraviolet performance of a PET food packaging coating comprises the following steps:

step one, preparation of a quantum dot zinc oxide solution:

(1) anhydrous zinc acetate (Zn (Ac)₂) Dissolving: taking 1 mol of Zn (Ac)₂Dispersing the mixture into 30 ~ 50mL of absolute ethyl alcohol, gradually heating to 75 ~ 80 ℃, and dispersing and dissolving for 2 ~ 3 h;

(2) dissolving sodium hydroxide (NaOH), namely taking 1 ~ 3 mol of NaOH, dispersing the NaOH in 10 ~ 30mL of absolute ethyl alcohol, and carrying out ultrasonic treatment for 10 ~ 20min under the power of 480W until the NaOH is dissolved;

(3) reacting Zn (Ac) in the step (1)₂Mixing the solution with the NaOH solution in the step (2) according to the molar ratio of 1:1 ~ 3, stirring at room temperature, and reacting for 1.5 ~ 3 h;

step two, coating zinc oxide (ZnO @ SiO) by silicon dioxide₂) The preparation of (1):

(1) adding tetraethoxysilane into the stirring quantum dot zinc oxide solution according to the molar ratio of Zn atoms to Si atoms of 1:1 ~ 3, and then adding water into the stirring quantum dot zinc oxide solution according to the molar ratio of tetraethoxysilane to water of 1:4 ~ 8;

(2) stirring for 24 ~ 30h, and stopping stirring until precipitate is generated;

(3) centrifuging and washing the product at 9000 ~ 10000rmp/min for 3 ~ 4 times (10 min each), collecting the product, and freeze drying;

step three, pigment ZnO @ SiO₂Preparation of the dispersion of (4):

the ZnO @ SiO obtained in the second step₂Dispersing in a certain amount of water, and dispersing at high speed with homogenizing emulsifier to obtain uniformly dispersed dispersion, i.e. pigment ZnO @ SiO₂The dispersion of (1);

step four, preparing and coating the ink-jet coating liquid:

(1) taking 10 ~ 30 parts of 2 ~ 20wt% PVA solution and 10 parts of pigment ZnO @ SiO₂70 ~ parts of the dispersion liquid, 1 ~ parts of boric acid and 5 ~ parts of ethanol are mixed and dispersed at high speed for 40 ~ min under a homogenizing emulsifying machine, and then the uniformly dispersed ink-jet coating liquid can be obtained;

(2) and (3) taking the PET film with a clean surface, coating the ink-jet coating liquid by using a coating machine, and then drying in an oven at 75 ~ 90 ℃ to obtain the PET film with the ink-jet coating.

Compared with the prior art, the invention has the following advantages:

1. introduction of ZnO quantum dots: the ZnO quantum dots can absorb most of ultraviolet light in the UV-A wave band, when the nano particles are used as the pigment of the ink-jet coating, the ZnO quantum dots can play the advantage of shielding the UV-A ultraviolet light, and when the coating is applied to the field of food packaging, the phenomenon that food is deteriorated due to ultraviolet radiation can be effectively prevented, so that the quality guarantee period of the food is prolonged.

2、SiO₂Coating ZnO quantum dots: when the ZnO quantum dot is used alone as an ultraviolet shielding agent, the ultraviolet can be shielded, and the photocatalytic degradation effect of the ultraviolet on the ZnO quantum dot, namely SiO, can not be avoided₂The coating of ZnO quantum dots greatly reduces the photocatalytic degradation effect. ZnO @ SiO₂When used as ink-jet coating pigment, the pigment avoids the reduction of printing effect caused by photodegradation, and can be applied to jet printingAnd (4) ink printing.

3. ZnO and SiO₂The combination of (1): ZnO @ SiO prepared by the invention₂Nanoparticles compared to commercial SiO₂Has higher porosity, thus greatly improving the ink absorption performance of the coating.

Drawings

FIG. 1 is a commercial SiO₂(A-200) nanoparticles and the pigment ZnO @ SiO prepared by the invention₂Nitrogen adsorption and desorption curves for nanoparticles.

FIG. 2 shows ZnO quantum dots and ZnO @ SiO₂Degradation of nanoparticles under 365nm ultraviolet light (with rhodamine B as a dye), a: ZnO quantum dots, b: ZnO @ SiO₂Nanoparticles.

FIG. 3 shows a simple PET film, a PVA coating and the addition of ZnO @ SiO₂Uv transmission spectrum of PVA coating of nanoparticles.

Detailed Description

The technical solution of the present invention is further described below with reference to the accompanying drawings, but not limited thereto, and any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention shall be covered by the protection scope of the present invention.