A surface modification method and product for improving the surface free energy of polyester film base for medical dry film

Abstract

The present invention provides a surface modification method for improving the surface free energy of a polyester sheet for medical dry film and its product, which relates to the field of medical dry film. The surface modification method for improving the surface free energy of a polyester sheet for medical dry film comprises the following operations: after spraying a PVP-Fe solution on the surface of a polyester sheet for medical dry film, spraying a tannic acid aqueous solution at least once. The surface modification method for improving the surface free energy of a polyester sheet for medical dry film of the present invention does not require corona treatment, effectively avoiding the problems of high-voltage discharge danger, high energy consumption, easy generation of harmful gases, dust and static electricity, and poor environmental friendliness existing in corona treatment; while effectively improving the surface free energy of a polyester sheet for medical dry film, it can increase the surface roughness of the polyester sheet, thereby facilitating the coating of a photosensitive layer, etc. in the subsequent medical dry film production process, and the preparation method has a high safety factor and high environmental friendliness.

Description

Technical Field

[0001] The present invention relates to the field of medical dry films, in particular to a surface modification method for improving the surface free energy of a polyester film base for medical dry films and a product thereof. Background Art

[0002] Dry medical film is a special film used for medical imaging, mainly used to record various medical images, such as X-rays, CT scans, and magnetic resonance imaging (MRI). Compared with traditional wet films, dry laser film has become the mainstream in medical imaging recording due to its high image quality, fast processing speed, and easy storage and transmission. Medical dry film uses a blue PET base as a support, with an imaging layer and a protective layer coated on both sides. The imaging layer and the protective layer need to be bonded to the PET base with an adhesive. However, PET material is a non-polar polymer, and its film surface free energy is low, the wettability is poor, and the surface adhesion is small. Theoretically, if the surface free energy of the material is less than 3.3×10 -6 J / cm 2 , then no currently known adhesive will be able to adhere to its surface. Therefore, to ensure that the imaging layer and protective layer materials are firmly attached to the surface of the PET substrate, the surface free energy of the PET substrate must be increased. Based on current processing technology, corona treatment is the most widely used method to increase the surface free energy of PET substrates. Corona treatment involves ionizing the PET surface under the impact of high-voltage, high-frequency spark discharges, generating polar functional groups, thereby converting its non-polar surface into a polar surface and increasing the surface free energy. In addition, corona treatment also impacts the PET substrate to "roughen" its surface, increasing its surface roughness. This in turn increases the contact area between the imaging layer, protective layer, and other materials and the PET substrate, further improving adhesion strength.

[0003] However, in actual production, corona treatment still faces significant limitations. First, the corona process requires high voltage electric fields, which poses a high risk. Second, the corona process produces harmful gases such as ozone and nitric oxide, which are harmful to human health and cause environmental pollution. Third, the corona treatment of PET film substrates generates dust, which adheres to the film and reduces the film's yield. Furthermore, films with dust particles attached to them are limited in their usability. Fourth, the corona process generates static electricity, which causes dust to attract the film and can cause adhesion during subsequent printing and development. Fifth, corona treatment can generate sparks, which can affect the coating of the imaging layer in subsequent production processes, increase the number of steps in the film production process, and reduce production efficiency. Furthermore, in the production of some medical dry films (such as thermal dry films), corona treatment cannot achieve the desired treatment results. Films prepared after corona treatment still suffer from poor adhesion of the imaging layer, significantly affecting film quality and printing efficiency.

[0004] Therefore, the development of a new method for increasing the surface free energy of polyester film base for medical dry film, which does not require corona treatment, effectively avoids the problems of high-voltage discharge danger, high energy consumption, easy generation of harmful gases, dust and static electricity, and poor environmental friendliness existing in corona treatment, has important technical significance and research value.

[0005] Furthermore, during the research and development process of surface modification using chemical methods to specifically improve the surface free energy of polyester film bases for medical dry films, the inventors discovered that due to the high hydrophobicity and low surface free energy of the polyester film base surface, conventional film-forming raw materials cannot form a uniform film on the surface of the polyester film base for medical dry films. Even if a film is formed, it cannot effectively adhere to the surface of the polyester film base for medical dry films. The film-forming effect and stability are poor, and it is impossible to increase the surface roughness of the polyester film base while effectively improving the surface free energy of the polyester film base for medical dry films. Summary of the Invention

[0006] In order to solve the technical problems existing in the prior art, the present invention provides a surface modification method for improving the surface free energy of a polyester film base for medical dry film. The method does not require corona treatment, effectively avoiding the problems of high-voltage discharge danger, high energy consumption, easy generation of harmful gases, dust and static electricity, and poor environmental friendliness existing in corona treatment. The method can effectively improve the surface free energy of the polyester film base for medical dry film while increasing the surface roughness of the polyester film base, thereby facilitating the coating of a photosensitive layer and the like in the subsequent medical dry film production process. The preparation method has a high safety factor and high environmental friendliness. The present invention also provides a product prepared by the above method.

[0007] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0008] A surface modification method for increasing the surface free energy of a polyester film base for medical dry film, characterized in that the surface modification method comprises the following operations: after uniformly spraying a PVP-Fe solution on the surface of the polyester film base for medical dry film, uniformly spraying a tannic acid aqueous solution at least once;

[0009] The PVP-Fe solution contains polyvinyl pyrrolidone and Fe 3+ of a mixed aqueous solution.

[0010] Preferably, in the PVP-Fe solution, the concentration of polyvinyl pyrrolidone is 2.0-3.9 g / L, and Fe 3+ The concentration is 0.5-1g / L.

[0011] Preferably, the concentration of tannic acid in the tannic acid aqueous solution is 8-12 g / L.

[0012] Preferably, the spraying amount of the PVP-Fe solution on each square centimeter of the polyester film base for medical dry film is 0.02-0.03 mL.

[0013] Preferably, the total spraying amount of the tannic acid aqueous solution on each square centimeter of the polyester film base for medical dry film is 0.02-0.03 mL.

[0014] Furthermore, the Fe in the PVP-Fe solution used 3+ Provided by FeCl3;

[0015] The weight ratio of FeCl3 in the PVP-Fe solution to tannic acid in the tannic acid aqueous solution is 1:4-5.5.

[0016] Furthermore, the surface modification method for increasing the surface free energy of a polyester film base for medical dry film comprises the following steps: preparing a PVP-Fe solution, preparing a tannic acid aqueous solution, and spraying to form a film;

[0017] The spray film forming method comprises the following steps: uniformly spraying a PVP-Fe solution onto the surface of a polyester film base for medical dry film, and then uniformly spraying a tannic acid aqueous solution onto the surface of the polyester film base for medical dry film at least once; after spraying the tannic acid aqueous solution, washing and removing excess liquid on the surface of the polyester film base for medical dry film, completing surface modification, and obtaining a surface-modified polyester film base for medical dry film.

[0018] Furthermore, the method for preparing the PVP-Fe solution is to dissolve polyvinyl pyrrolidone in deionized water, then add FeCl3 solution, mix well, and prepare the PVP-Fe solution;

[0019] The method for preparing the tannic acid aqueous solution comprises the following steps: placing tannic acid in deionized water and uniformly dispersing the tannic acid in deionized water to obtain the tannic acid aqueous solution.

[0020] Preferably, the spraying amount of the PVP-Fe solution per square centimeter of the polyester film base for medical dry film is equal to the total spraying amount of the tannic acid aqueous solution per square centimeter of the polyester film base for medical dry film.

[0021] A polyester film base for medical dry film is obtained by using the above-mentioned surface modification method.

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

[0023] (1) In the surface modification method for improving the surface free energy of the polyester film base for medical dry film of the present invention, the tannic acid used is a natural polyphenol compound, which contains a large number of pyrogallol hydroxyl groups in its molecular structure and has a strong chelating ability for metal ions. The inventors have found through research that tannic acid can form a metal polyphenol film on the surface of the polyester film base through coordination complexation and self-assembly with iron ions. The formed metal polyphenol film can effectively improve the polarity and hydrophilicity of the material surface, and the thickness and surface roughness of the metal polyphenol film can be regulated by controlling the reaction conditions. Based on this, the present invention adopts a "two-step method" strategy to modify the polyester film surface with a tannic acid iron film to increase its surface polarity and thereby improve its surface free energy. At the same time, in the process of modifying the polyester film surface with a tannic acid iron film, there is a problem of poor modification efficiency. In order to overcome this problem, the present invention uses a precursor solution (i.e., Fe 3+ The metal complexing agent polyvinyl pyrrolidone (PVP) with surface active effect was introduced into the solution, and the metal complexing agent polyvinyl pyrrolidone (PVP) was used to react with Fe 3+ The weak coordination effect and film-forming property of Fe on the surface of polyester film make Fe 3+ It is more evenly coated on the surface of the polyester base. At the same time, the introduction of PVP also helps to further improve the polarity and hydrophilicity of the PET base surface, and further improve the surface free energy of the polyester base.

[0024] (2) The surface modification method for improving the surface free energy of the polyester film base for medical dry film of the present invention is simple to implement. The method comprises spraying PVP and Fe 3+ A tannic acid iron film can be formed on the surface of the PET substrate by using an aqueous solution (i.e., PVP-Fe solution) and a tannic acid aqueous solution. The tannic acid iron film can reduce the surface free energy of the polyester substrate from 4.66×10 -6 J / cm 2 Increased to 6.25×10 -6 J / cm 2 The surface roughness of the polyester film base can be effectively increased, further facilitating the subsequent coating of adhesives, photosensitive layers, and protective layers in the production of medical dry films. Furthermore, compared with traditional corona treatment, the surface modification method of the present invention offers a higher safety factor and greater environmental friendliness, effectively avoiding the high-voltage discharge hazards, high energy consumption, and the generation of harmful gases, dust, and static electricity associated with corona treatment, which poses a significant environmental risk.

[0025] (3) The surface modification method of the present invention for increasing the surface free energy of the polyester film base for medical dry film can be completed by spraying PVP-Fe solution and ferric tannate solution in sequence. The raw materials are cheap and easy to obtain. The area of ​​the polyester film base can be expanded according to the production scale, and the volume of the spray solution required for surface modification can be increased accordingly, thereby realizing large-scale industrial production.

[0026] (4) Through the surface modification method of the present invention for improving the surface free energy of the polyester film base for medical dry film, the thickness of the tannic acid iron complex film on the surface of the surface modified polyester film base is 15-30 μm, and the surface roughness of the surface modified polyester film base is significantly increased, and the surface free energy is increased from 4.66×10 -6 J / cm 2 Increased to 6.25×10 -6 J / cm 2 . BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a scanning electron microscope image of the longitudinal section of the PET substrate modified with the iron tannate film prepared in Example 1.

[0028] Figure 2 These are scanning electron microscope images of the PET substrate surface before (a) and after (b) modification with the iron tannate film in Example 1.

[0029] Figure 3 1 and 2 are the contact angles of water on the PET substrate surface before (a) and after (b) modification with the iron tannate film in Example 1.

[0030] Figure 4 : The contact angles of formamide on the PET substrate surface before (a) and after (b) modification with the iron tannate film in Example 1. DETAILED DESCRIPTION

[0031] In order to provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention are now described. It should be noted that the following detailed description is illustrative and is intended to further illustrate the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0032] It should be noted that the terms used herein are intended only to describe specific embodiments and are not intended to limit the exemplary embodiments of the present invention. As used herein, "first," "second," and the like are used to distinguish similar objects and are not used to describe a specific order or precedence. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0033] The embodiment of the present invention provides a surface modification method for improving the surface free energy of a polyester film base for medical dry film, which is carried out by increasing the surface free energy and surface roughness of the PET film base. Specifically, the surface modification method comprises spraying a coating containing polyvinyl pyrrolidone (PVP) and Fe on the surface of the polyester film base for medical dry film. 3+ After the mixed aqueous solution (i.e., PVP-Fe solution) is applied, the tannic acid aqueous solution is sprayed at least once.

[0034] In the surface modification method for improving the surface free energy of a polyester film base for medical dry film of the present invention, polyvinyl pyrrolidone in a PVP-Fe solution is used as a metal complexing agent to bind with iron ions. The wettability and affinity of polyvinyl pyrrolidone for the surface of the high-molecular polyester film base are utilized to improve the uniform distribution of iron ions on the surface of the polyester film base, which is conducive to forming a uniform iron tannate film on the surface of the polyester film base when a tannic acid solution is subsequently sprayed. After the PVP-Fe solution is sprayed, the tannic acid aqueous solution is sprayed. A large amount of catechol is present in the tannic acid and the tannic acid-iron complex formed by the tannic acid and the iron ions, which can effectively bind to the surface of the polyester film base for medical dry film, reduce the hydrophobicity of the polyester film base surface, and improve the surface energy.

[0035] In the embodiment of the present invention, the concentration of polyvinylpyrrolidone (PVP) in the PVP-Fe solution is 2.0-3.9 g / L, preferably 2.5-3.5 g / L; Fe 3+ The concentration is 0.5-1 g / L, preferably 0.6-0.9 g / L.

[0036] In an embodiment of the present invention, the concentration of tannic acid in the tannic acid aqueous solution is 8-12 g / L, preferably 9-12 g / L.

[0037] Furthermore, in a preferred embodiment of the present invention, the preparation method of the PVP-Fe solution is as follows: a certain amount of PVP is weighed and dissolved in deionized water, and then a 0.1 g / mL FeCl3 solution is added to the above solution, and the mixture is mixed to obtain a polyvinylpyrrolidone PVP concentration of 2.0-3.9 g / L and a FeCl3 concentration of 1.5-2.9 g / L (corresponding to Fe 3+ Prepare a PVP-Fe solution with a concentration of 0.5-1 g / L for later use.

[0038] Furthermore, in a preferred embodiment of the present invention, the preparation method of the tannic acid aqueous solution is: weigh a certain amount of tannic acid and dissolve it in deionized water, mix it evenly to obtain a tannic acid aqueous solution with a tannic acid concentration of 8-10 g / L, and set it aside.

[0039] Specifically, the surface modification method for improving the surface free energy of the polyester film base for medical dry film comprises the following steps:3+ A mixed aqueous solution (i.e., PVP-Fe solution) is evenly sprayed on the surface of a polyester film base for medical dry film, and then a tannic acid aqueous solution is evenly sprayed on the surface of the polyester film base for medical dry film at least once. The two solutions can react upon contact to form a layer of tannic acid iron film on the surface of the polyester film base. After the tannic acid aqueous solution is sprayed, the surface of the polyester film base for medical dry film is washed with clean water to remove excess liquid that has not reacted, thereby completing the surface modification and obtaining a surface-modified polyester film base for medical dry film.

[0040] In the embodiment of the present invention, the weight ratio of FeCl3 in the PVP-Fe solution to tannic acid in the tannic acid aqueous solution is 1:4-5.5.

[0041] In the embodiment of the present invention, by spraying the tannic acid aqueous solution at least once, the controllability of the film thickness and roughness can be further improved while ensuring that the surface of the polyester film base for medical dry film is fully modified.

[0042] Furthermore, in a preferred embodiment of the present invention, the polyvinyl pyrrolidone (PVP) and Fe 3+ A mixed aqueous solution (i.e., a PVP-Fe solution) is evenly sprayed on the surface of a polyester film base for medical dry film, and then an equal volume of a tannic acid aqueous solution is evenly sprayed on the surface of the polyester film base for medical dry film, and the spraying amount of the PVP-Fe solution and the tannic acid aqueous solution is controlled to be 0.02-0.03 mL per square centimeter of the polyester film base for medical dry film. After the spraying of the tannic acid aqueous solution is completed, the surface of the polyester film base for medical dry film is washed with clean water to remove excess liquid that has not reacted, thereby completing the surface modification and obtaining a surface-modified polyester film base for medical dry film, the thickness of the tannic acid iron complex film on the surface of which is 15-30 μm.

[0043] The present invention will be further described below with reference to some specific embodiments.

[0044] The sources of some reagents used in the subsequent examples are as follows: tannic acid (99%), FeCl3, and polyvinylpyrrolidone PVP (molecular weight 40 kDa) were all purchased from Aladdin (China) Company.

[0045] Example 1

[0046] This embodiment provides a surface modification method for increasing the surface free energy of a polyester film base for medical dry film, specifically modifying the surface of the polyester film base for medical dry film with an iron tannate film:

[0047] 1. Preparation of PVP-Fe solution

[0048] Weigh 0.6 g of polyvinylpyrrolidone (PVP) and dissolve it in 200 mL of deionized water. Then, add 4 mL of a 0.1 g / mL FeCl3 solution to the above solution and mix well to prepare a PVP-Fe solution for later use.

[0049] 2. Preparation of tannic acid aqueous solution

[0050] Weigh 2.0 g of tannic acid and dissolve it in 200 mL of deionized water. Mix well to prepare a tannic acid aqueous solution for later use.

[0051] 3. Spraying film

[0052] A polyester film base for medical dry film having a side length of 50 cm × 50 cm was taken, and 50 mL of the above-mentioned PVP-Fe solution was first evenly sprayed on the surface of the polyester film base. After the PVP-Fe solution was sprayed, an equal volume of tannic acid aqueous solution was continued to be evenly sprayed on the surface of the polyester film base. After the tannic acid aqueous solution was sprayed, the surface of the polyester film base for medical dry film was washed with clean water to remove excess liquid that had not reacted, thereby completing the surface modification and obtaining a surface-modified polyester film base for medical dry film.

[0053] The weight ratio of FeCl3 in the PVP-Fe solution to tannic acid in the tannic acid aqueous solution is 1:5.1.

[0054] The spraying amount of the PVP-Fe solution and the tannic acid aqueous solution on each square centimeter of the polyester film base for medical dry film is 0.02 mL.

[0055] This embodiment also provides a polyester film base for medical dry film after surface modification prepared by the above method. Figure 1 From the scanning electron microscope characterization pictures of the polyester film base for medical dry film after surface modification, it can be seen that the thickness of the tannic acid iron complex film modified on the surface of the polyester film base for medical dry film using the surface modification method of this embodiment is about 18 μm, and the surface is obviously rough after the surface modification is completed (such as Figure 2 As shown), the surface roughness of the polyester base for medical dry film is effectively increased, which is beneficial for the subsequent adhesion of adhesives, imaging layers, protective layers and other materials on the surface of the polyester base.

[0056] The surface free energy of the polyester film base for medical dry film after surface modification in this embodiment is calculated by the following method:

[0057] The surface free energy of contact between solid and liquid can be expressed by the formula: ;

[0058] Among them, γ sv is the surface free energy, γ P svis the polar part of the surface free energy, γ d sv is the dispersion part of the surface free energy. P sv and γ d sv It can be calculated by the following formula:

[0059] ;

[0060] Where θ is the contact angle of the liquid on the solid surface, γ LV is the interfacial free energy between liquid and air (liquid-gas) (constant, which can be obtained by looking up the table), γ d LV and γ p LV They are the dispersion part and polar part of the liquid-gas interface free energy respectively (obtained by looking up the table).

[0061] Therefore, the surface free energy of the polyester film base for medical dry film can be calculated by measuring the contact angles of liquid water and formamide on its surface and then substituting them into the above formula.

[0062] like Figure 3-4 As shown in Table 1, at 20°C, the contact angles of water on the surface of the polyester film base for medical dry film and the surface of the polyester film base for medical dry film modified with the iron tannate film were 84.3° and 31.6°, respectively. The contact angles of formamide on the surface of the polyester film base for medical dry film and the surface of the polyester film base for medical dry film modified with the iron tannate film were 50.9° and 20.5°, respectively. The liquid-gas interfacial free energy data of water and formamide are shown in Table 1 below. Substituting them into the above formula, the surface free energy of the polyester film base for medical dry film before modification is 46.6 mN / m (4.66×10 -6 J.cm -2 ), the surface free energy of the polyester film base for medical dry film after modification with iron tannate film is 62.5mN / m (6.25×10 -6 J.cm -2 The results show that the modification of the iron tannate film in this embodiment can effectively increase the surface free energy of the polyester film base for medical dry film, which is beneficial to the adhesion of subsequent adhesives and imaging layers, protective layers and other materials to the surface of the polyester film base for medical dry film.

[0063] Table 1: Liquid-air interface free energy parameters

[0064]

[0065] Example 2

[0066] This embodiment provides a surface modification method for increasing the surface free energy of a polyester film base for medical dry film, specifically modifying the surface of the polyester film base for medical dry film with an iron tannate film:

[0067] 1. Preparation of PVP-Fe solution

[0068] Weigh 0.7 g of polyvinylpyrrolidone (PVP) and dissolve it in 200 mL of deionized water. Then, add 4.8 mL of 0.1 g / mL FeCl3 solution to the above solution and mix well to prepare PVP-Fe solution for later use.

[0069] 2. Preparation of tannic acid aqueous solution

[0070] Weigh 1.9 g of tannic acid and dissolve it in 200 mL of deionized water. Mix well to prepare a tannic acid aqueous solution, which is set aside.

[0071] 3. Spraying film

[0072] A polyester film base for medical dry film having a side length of 50 cm × 50 cm was taken, and 50 mL of the above-mentioned PVP-Fe solution was first evenly sprayed on the surface of the polyester film base. After the PVP-Fe solution was sprayed, an equal volume of tannic acid aqueous solution was continued to be evenly sprayed on the surface of the polyester film base. After the tannic acid aqueous solution was sprayed, the surface of the polyester film base for medical dry film was washed with clean water to remove excess liquid that had not reacted, thereby completing the surface modification and obtaining a surface-modified polyester film base for medical dry film.

[0073] The weight ratio of FeCl3 in the PVP-Fe solution to tannic acid in the tannic acid aqueous solution is 1:4.

[0074] The spraying amount of the PVP-Fe solution and the tannic acid aqueous solution on each square centimeter of the polyester film base for medical dry film is 0.02 mL.

[0075] This embodiment also provides a surface-modified polyester film base for medical dry film prepared using the aforementioned method. Testing revealed that the water contact angle of the surface of the surface-modified polyester film base for medical dry film was 35.5°, and the formamide contact angle was 22.1°. The surface free energy of the surface-modified polyester film base for medical dry film calculated using the aforementioned method was 60.1 mN / m (6.01×10 -6 J.cm -2 ).

[0076] Example 3

[0077] This embodiment provides a surface modification method for increasing the surface free energy of a polyester film base for medical dry film, specifically modifying the surface of the polyester film base for medical dry film with an iron tannate film:

[0078] 1. Preparation of PVP-Fe solution

[0079] Weigh 0.5 g of polyvinylpyrrolidone (PVP) and dissolve it in 200 mL of deionized water. Then, add 4.5 mL of 0.1 g / mL FeCl3 solution to the above solution and mix well to prepare PVP-Fe solution for later use.

[0080] 2. Preparation of tannic acid aqueous solution

[0081] Weigh 2.4 g of tannic acid and dissolve it in 200 mL of deionized water. Mix well to prepare a tannic acid aqueous solution, which is set aside.

[0082] 3. Spraying film

[0083] A polyester film base for medical dry film having a side length of 50 cm × 50 cm was taken, and 50 mL of the above-mentioned PVP-Fe solution was first evenly sprayed on the surface of the polyester film base. After the PVP-Fe solution was sprayed, an equal volume of tannic acid aqueous solution was continued to be evenly sprayed on the surface of the polyester film base. After the tannic acid aqueous solution was sprayed, the surface of the polyester film base for medical dry film was washed with clean water to remove excess liquid that had not reacted, thereby completing the surface modification and obtaining a surface-modified polyester film base for medical dry film.

[0084] The weight ratio of FeCl3 in the PVP-Fe solution to tannic acid in the tannic acid aqueous solution is 1:5.4.

[0085] The spraying amount of the PVP-Fe solution and the tannic acid aqueous solution on each square centimeter of the polyester film base for medical dry film is 0.02 mL.

[0086] This embodiment also provides a surface-modified polyester film base for medical dry film prepared using the aforementioned method. Testing has shown that the water contact angle of the surface of the surface-modified polyester film base for medical dry film is 36.8°, and the formamide contact angle is 23.1°. The surface free energy of the surface-modified polyester film base for medical dry film calculated using the aforementioned method is 59.3 mN / m (5.93×10 -6 J.cm -2 ).

[0087] Comparative Example 1

[0088] Comparative Example 1 adopts the technical solution of Example 1, except that the addition of polyvinylpyrrolidone (PVP) is omitted, and a solution containing only FeCl3 is used instead of the PVP-Fe solution for spraying, and then a tannic acid aqueous solution is used for spraying.

[0089] After testing, the water contact angle of the surface of the polyester film base for medical dry film after surface modification in Comparative Example 1 was 53.3°, and the formamide contact angle was 35.3°. The surface free energy of the polyester film base for medical dry film after surface modification calculated by the above method was 49.1 mN / m (4.91×10 -6 J.cm -2 ). The test data of Comparative Example 1 shows that the introduction of polyvinyl pyrrolidone (PVP) plays an important role in reducing the surface free energy of the polyester substrate surface during film modification. Analysis shows that when the addition of polyvinyl pyrrolidone (PVP) is omitted, the iron ions cannot be evenly coated on the polyester substrate surface, resulting in poor film-forming properties and uniformity of the iron tannate film formed on the polyester substrate surface, ultimately leading to poor surface modification results.

[0090] Unless otherwise specified, all percentages used in the present invention are by mass.

[0091] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A surface modification method for increasing the surface free energy of a polyester film base for medical dry film, characterized in that: The surface modification method comprises the following steps: evenly spraying a PVP-Fe solution on the surface of a polyester film base for medical dry film, and then evenly spraying a tannic acid aqueous solution at least once; The PVP-Fe solution contains polyvinyl pyrrolidone and Fe 3+ The PVP-Fe solution, the concentration of polyvinyl pyrrolidone is 2.0-3.9g / L, Fe 3+ Concentration is 0.5-1g / L; In the tannic acid aqueous solution, the concentration of tannic acid is 8-12 g / L; The spraying amount of the PVP-Fe solution on each square centimeter of the polyester film base for medical dry film is 0.02-0.03 mL; The total spraying amount of the tannic acid aqueous solution on each square centimeter of the polyester film base for medical dry film is 0.02-0.03 mL.

2. The surface modification method for increasing the surface free energy of a polyester film base for medical dry film according to claim 1, characterized in that: The Fe content in the PVP-Fe solution used 3+ Provided by FeCl3; The weight ratio of FeCl3 in the PVP-Fe solution to tannic acid in the tannic acid aqueous solution is 1:4-5.

5.

3. The surface modification method for increasing the surface free energy of a polyester film base for medical dry film according to claim 1, characterized in that: The method comprises the following steps: preparing a PVP-Fe solution, preparing a tannic acid aqueous solution, and spraying to form a film; The spray film forming method comprises the following steps: uniformly spraying a PVP-Fe solution onto the surface of a polyester film base for medical dry film, and then uniformly spraying a tannic acid aqueous solution onto the surface of the polyester film base for medical dry film at least once; after spraying the tannic acid aqueous solution, washing and removing excess liquid on the surface of the polyester film base for medical dry film, completing surface modification, and obtaining a surface-modified polyester film base for medical dry film.

4. The surface modification method for increasing the surface free energy of a polyester film base for medical dry film according to claim 3, characterized in that: The method for preparing the PVP-Fe solution is to dissolve polyvinyl pyrrolidone in deionized water, then add FeCl3 solution, mix well, and prepare the PVP-Fe solution; The method for preparing the tannic acid aqueous solution comprises the following steps: placing tannic acid in deionized water and uniformly dispersing the tannic acid in deionized water to obtain the tannic acid aqueous solution.

5. The surface modification method for increasing the surface free energy of a polyester film base for medical dry film according to claim 3, characterized in that: The spraying amount of the PVP-Fe solution on each square centimeter of the polyester film base for medical dry films is equal to the total spraying amount of the tannic acid aqueous solution on each square centimeter of the polyester film base for medical dry films.

6. A polyester film base for medical dry film, characterized in that: The surface modification method according to any one of claims 1 to 5 is used for treatment.

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