阅读说明：本技术 一种耐水型pva膜制备方法 (Preparation method of water-resistant PVA film ) 是由 李淑君 何婷 陈志俊 王慧 任世学 马艳丽 于 2018-07-03 设计创作，主要内容包括：本发明公开了一种耐水型PVA膜制备方法。本发明提高了现有PVA膜对水作用的抵抗能力。利用聚乙烯醇(PVA)作为膜材料。本发明所述的一种耐水型PVA膜制备方法如下：(一)槲皮素的提取：将富含槲皮素的原料进行提取、多级分离提纯。(二)槲皮素纳米晶体的制备：将提取的槲皮素溶于四氢呋喃-水混合溶剂体系中；(三)耐水型PVA膜制备：将槲皮素纳米晶体溶液和PVA溶液混合搅拌,干燥处理。本发明所述的耐水型PVA膜在水中浸泡1min后取出,形状基本保持不变,体积变化率小于10％,且不发生卷曲现象。(The invention discloses a preparation method of a water-resistant PVA film. The invention improves the resistance of the existing PVA film to water action. Polyvinyl alcohol (PVA) was used as the membrane material. The preparation method of the water-resistant PVA film comprises the following steps: firstly, extracting quercetin: extracting raw materials rich in quercetin, and performing multi-stage separation and purification. (II) preparing quercetin nanocrystals: dissolving the extracted quercetin in a tetrahydrofuran-water mixed solvent system; (III) preparing a water-resistant PVA film: mixing the quercetin nanocrystal solution and the PVA solution, stirring, and drying. The water-resistant PVA film disclosed by the invention is taken out after being soaked in water for 1min, the shape is basically kept unchanged, the volume change rate is less than 10%, and the curling phenomenon is avoided.)

1. A preparation method of a water-resistant PVA film is characterized by comprising the following steps: firstly, extracting quercetin: the raw material rich in quercetin is subjected to multi-stage extraction, separation and purification. (II) preparing quercetin nanocrystals: dissolving the extracted quercetin in a mixed solvent system of tetrahydrofuran-water; (III) preparing a water-resistant PVA film: mixing and stirring the quercetin nanocrystal solution and the PVA solution, and then drying. The invention solves the problems that the existing PVA film has good hydrophilicity, is easy to swell when contacting liquid and has a hole breaking phenomenon, and fundamentally ensures the water resistance of the PVA film.

2. The method for preparing a water-resistant PVA film according to claim 1, wherein the raw material in the step (one) is rich in quercetin, such as lotus leaf, sophora flower bud, tea leaf, etc.

3. The method for preparing a water-resistant PVA film according to claim 1, wherein the extraction, separation and purification of quercetin in the step (I) mainly comprises reflux extraction, ultrasonic extraction, etc.

4. The method for preparing a water-resistant PVA film according to claim 1, wherein in the step (two), when preparing the quercetin nanocrystals, the quercetin is dissolved in a tetrahydrofuran-water system at a volume fraction ratio of 1:9 to 1:1, preferably 2: 8.

5. the method for preparing a water-resistant PVA film according to claim 1, wherein the mass ratio of two kinds of PVA with different polymerization degrees (DP 1750 and DP 1788) in the polyvinyl alcohol solution in the step (III) is 1: 9-9: 1, preferably 1: 1.

6. the method for preparing a water-resistant PVA film according to claim 1, wherein in the third step (c), the mass ratio of the quercetin to the polyvinyl alcohol solid is 1:100 to 1:1000, preferably 1: 500.

Technical Field

The invention relates to a preparation method of a high polymer material, and in particular relates to a preparation method of a water-resistant PVA film.

Background

Polyvinyl alcohol (PVA), a water-soluble polymer obtained by hydrolysis of polyvinyl acetate. The main chain of the molecule is a carbon-carbon chain, and the side chain of the molecule also comprises a plurality of hydrophilic compounds of hydroxyl. The water-soluble chitosan-chitosan composite material not only contains hydrophilic high-activity hydroxyl, but also contains hydrophobic acetyl, and the ratio, polymerization degree and spatial structure of the two have great influence on the properties of the water-soluble chitosan-chitosan composite material. The film prepared by PVA has the characteristics of no toxicity, no odor, high transparency, no dust absorption, good mechanical property and the like, and particularly has the outstanding characteristics of complete biodegradation and good water solubility, and meets the requirement of green environmental protection development. The existing PVA film is easy to swell when contacting liquid, and the phenomenon of hole breaking occurs.

Disclosure of Invention

The invention aims to solve the problems that the existing PVA film is easy to swell and generate holes when contacting liquid, and fundamentally ensures the water resistance of the PVA film.

The invention relates to a preparation method of a water-resistant PVA film, which is characterized by comprising the following steps: firstly, extracting quercetin: the raw material rich in quercetin is subjected to multi-stage extraction, separation and purification. (II) preparing quercetin nanocrystals: dispersing the extracted quercetin in a tetrahydrofuran-water (v/v ═ 1: 9-1: 1) mixed solvent system; (III) preparation of a water-resistant PVA film: mixing and stirring the quercetin nanocrystal solution and the PVA solution, and then drying. Wherein the selected raw materials are rich in quercetin, such as folium Nelumbinis, flos Sophorae Immaturus, folium Camelliae sinensis, etc.; in order to obtain pure quercetin as far as possible, different purification modes such as a reflux method, ultrasonic extraction and the like are adopted; when preparing the quercetin nanocrystals, dissolving quercetin in a tetrahydrofuran-water system, wherein the volume fraction ratio of the two in the solvent system is 1: 9-1: 1; the mass ratio of two kinds of PVA with different polymerization degrees (DP 1750 and DP 1788) in the polyvinyl alcohol solution is 1: 9-9: 1, preferably 1: 1; the mass ratio of the quercetin to the polyvinyl alcohol solid is 1: 100-1: 1000, and preferably 1: 500.

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

1. quercetin widely exists in nature, is a phenolic compound, does not need complicated synthetic process, has simple extraction process, convenient operation and no pollution, and does not relate to chemical reaction, thereby greatly simplifying the preparation process.

2. Solves the problems that the existing PVA film is easy to swell and generate holes when contacting liquid, and fundamentally ensures the water resistance of the PVA film. The water-resistant PVA film is taken out after being soaked in water for 1min, the shape is basically kept unchanged, the volume change rate is less than 10 percent, and the curling phenomenon is avoided.

Drawings

Fig. 1 is a sectional SEM image of a general water-insoluble PVA (DP 1750) film.

FIG. 2 is a sectional SEM photograph of a water-resistant PVA film obtained in the first embodiment.

Detailed Description