Preparation method of modified PVB peelable optical cleaning film

Abstract

The invention discloses a preparation method of a modified PVB peelable optical cleaning film. The preparation method comprises the following steps: 1) successively adding triethylamine and perfluorooctanoyl chloride into a 5%-10% PVB solution, and then reacting for 0.5-6 hours under the closed condition of 25-60 DEG C to obtain a modified PVB solution; 2) cooling the modified PVB solution, and washing with water for 2-4 times to enable the pH value of the solution to be 6.5-7.5; 3) drying the washed modified PVB solution in vacuum until the water content is less than 5%; 4) dissolving the dried modified PVB in a composite organic solvent to obtain a modified PVB coating solution; and 5) coating the surface of an instrument with the modified PVB film coating solution, and drying to form the modified PVB peelable optical cleaning film. The modified PVB peelable optical cleaning film prepared by the method provided by the invention has good film-forming property and cleaning ability.

Description

Technical Field

[0001] The invention relates to the field of cleaning and protection of optical and precision instruments, and in particular to a method for preparing a modified PVB peelable optical cleaning film. Background Art

[0002] Traditional cleaning of optical instruments usually uses mechanical methods for cleaning, which is not only not comprehensive enough for cleaning optical components, but also may cause damage to the components. Replacing the traditional mechanical cleaning method with a strippable coating cleaning method has the advantages of comprehensive and fast cleaning, easy operation, and no damage to optical components. The film-forming material of the strippable coating is mainly composed of polymers, and the common ones are polyurethane, polyvinyl alcohol, polyvinyl butyral ester, silicone, acrylic resin, chloroacetic resin, ethyl cellulose, etc. However, the film-forming time of common strippable coatings is long, and the toughness is not enough, especially the peeling force with the clean surface is high, it is not easy to peel off a large area, and it is easy to damage the surface functional coating of the optical component during the peeling process. The polyvinyl butyral ester (PVB) film has good solubility, easy film formation, good mechanical properties, can withstand a certain tensile force without being torn, and is soluble in a variety of non-toxic or low-toxic organic solvents such as ketones, alcohols, esters, etc. It is environmentally friendly and has good aging resistance, weather resistance, water resistance, insulation and other excellent properties. However, the hydroxyl group on the surface of PVB has a high adhesion to the optical surface and is not easy to peel off after film formation. Therefore, it cannot be directly used as a raw material for the peelable coating of optical components. Summary of the invention

[0003] The purpose of the present invention is to solve the problems and shortcomings of the cleaning method used in optical instruments, and to provide a method for preparing a modified PVB strippable optical cleaning film. The present invention grafts a perfluorinated structure onto a PVB molecule through the reaction of an acyl chloride group with a hydroxyl group in PVB, prepares a fluorinated modified PVB strippable optical cleaning coating film, reduces the surface tension of the PVB strippable solution, improves the hydrophobicity and permeability of the PVB strippable optical cleaning film, and the fluorine-modified PVB strippable film has a low peeling force with the surface, and is easily stripped after film formation, thereby avoiding damage to the optical surface.

[0004] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is as follows:

[0005] A method for preparing a modified PVB strippable optical cleaning film comprises the following steps:

[0006] 1) Synthesis of modified PVB solution (synthesized by solution free radical copolymerization):

[0007] The dried polyvinyl butyral ester and anhydrous tetrahydrofuran are stirred and dissolved in a mass ratio of 1:10-20 to obtain a 5%-10% PVB solution; the acetalization degree of the polyvinyl butyral ester is 68.0-80.0%, the residual hydroxyl content is greater than 20%, and the free acid is less than 0.05%;

[0008] Triethylamine and perfluorooctanoyl chloride are added to the PVB solution in sequence, wherein the molar ratio of triethylamine to hydroxyl groups in PVB is 1:1.2-1.5, and the molar ratio of perfluorooctanoyl chloride to hydroxyl groups in PVB is 1:1.2-1.5, and then reacted at 25-60° C. under closed conditions for 0.5-6 hours to obtain a modified PVB solution.

[0009] The synthesis equation is shown below;

[0010]

[0011] Formula 1 Synthesis reaction formula of modified PVB solution

[0012] 2) Water washing: After cooling the modified PVB solution, add it dropwise into the stirred deionized water to precipitate the white filamentous modified PVB, filter it, and then wash it with water for 2 to 4 times until the pH value of the solution is 6.5 to 7.5;

[0013] 3) Dehydration and drying: vacuum drying the modified PVB solution after washing until the moisture content is less than 5%;

[0014] 4) Dissolving: dissolving 10 to 25 parts of the dried modified PVB into 40 to 120 parts of the composite organic solvent by mass to obtain a modified PVB coating solution;

[0015] The composite organic solvent is composed of 10 to 30 parts of anhydrous ethanol, 10 to 40 parts of propylene glycol methyl ether, 10 to 20 parts of dimethyl acetal, and 10 to 30 parts of ethyl acetate in parts by mass;

[0016] 5) Preparation of cleaning film: The modified PVB coating solution is coated on the surface of the instrument and dried at a temperature of 25 to 45° C. for 0.5 to 24 h to form a modified PVB strippable optical cleaning film.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] 1. The present invention grafts a perfluorinated structure onto PVB by reacting an acyl chloride functional group with a hydroxyl group, thereby reducing the surface energy and bonding performance of PVB, reducing the peeling force between the modified PVB and the clean surface, improving the cleaning effect and protective ability of PVB, and enabling the cleaning film to remove surface pollutants more quickly and efficiently, thereby improving the cleaning efficiency.

[0019] 2. The present invention can not only play a good cleaning and protection effect on optical instruments, but also has good transparency and clarity. The surface of the prepared modified PVB peelable optical cleaning film is hydrophobic, which can effectively resist the erosion of moisture and humid environment, and keep the film surface clean and dry.

[0020] 3. The modified PVB peelable optical cleaning film has good peelability. When used to remove pollutants on the surface, it can be easily peeled off from the surface of the object to avoid damage to the surface.

[0021] 4. The modified PVB coating solution has relatively little impact on the environment during use, mainly because it is used as a coating or coating, and does not involve large-scale energy consumption or pollutant emissions. The modified PVB coating solution prepared by the present invention is non-toxic or low-toxic, environmentally friendly, and easy to store. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a FTIR comparison chart of the existing PVB and the modified PVB of the present invention;

[0023] Figure 2 This is a comparison chart of stain removal of the existing PVB and the modified PVB of the present invention under an optical microscope;

[0024] Figure 3 Comparison of peel strength between existing PVB and modified PVB of the present invention. DETAILED DESCRIPTION

[0025] Example 1

[0026] A method for preparing a modified PVB strippable optical cleaning film comprises the following steps:

[0027] 1) Synthesis of modified PVB solution:

[0028] The dried PVB and anhydrous tetrahydrofuran were uniformly stirred at a mass ratio of 1:10 to obtain a 10% PVB solution; triethylamine and perfluorooctanoyl chloride were added to the PVB solution in sequence, wherein the molar ratio of the triethylamine to the hydroxyl group in the PVB was 1:1.2, and the molar ratio of the perfluorooctanoyl chloride to the hydroxyl group in the PVB was 1:1.2, and then the mixture was reacted at 50° C. under a closed condition for 4 hours to obtain a modified PVB solution;

[0029] 2) Washing with water: After cooling the modified PVB solution, add it dropwise into the stirred deionized water to precipitate the white filamentous modified PVB, filter it, and then wash it with water for 3 times until the pH value of the solution reaches 7.0;

[0030] 3) Dehydration and drying: vacuum drying the modified PVB solution after washing until the moisture content is less than 5%;

[0031] 4) Dissolving: Dissolving 18 parts of the dried modified PVB into 75 parts of the composite organic solvent by mass to obtain a modified PVB coating solution;

[0032] Wherein, the composite organic solvent is composed of 15 parts of anhydrous ethanol, 25 parts of propylene glycol methyl ether, 15 parts of dimethyl acetal, and 20 parts of ethyl acetate (by mass);

[0033] 5) Preparation of cleaning film: The modified PVB coating solution is coated on the surface of the instrument and dried at room temperature for 24 hours to form a modified PVB peelable optical cleaning film.

[0034] Table 1 FTIR comparative analysis of existing PVB and modified PVB of the present invention

[0035]

[0036]

[0037] FTIR comparison of existing PVB and modified PVB of the present invention Figure 1 As shown, modified PVB 3448cm -1 The -OH absorption peak at 1272 cm -1 The CF stretching vibration absorption peak appears at , indicating that PVB is successfully grafted onto the perfluorinated structure.

[0038] Example 2

[0039] A method for preparing a modified PVB strippable optical cleaning film comprises the following steps:

[0040] 1) Synthesis of modified PVB solution:

[0041] The dried PVB and anhydrous tetrahydrofuran were uniformly stirred at a mass ratio of 1:15 to obtain a 6.7% PVB solution; triethylamine and perfluorooctanoyl chloride were successively added to the PVB solution, wherein the molar ratio of the triethylamine to the hydroxyl group in the PVB was 1:1.35, and the molar ratio of the perfluorooctanoyl chloride to the hydroxyl group in the PVB was 1:1.35, and then the mixture was reacted at 50° C. under a closed condition for 4 hours to obtain a modified PVB solution;

[0042] 2) Water washing: After cooling the modified PVB solution, add it dropwise into the stirred deionized water to precipitate the white filamentous modified PVB. After filtering, wash it with water for 3 times until the pH value of the solution reaches 7.0.

[0043] 3) Dehydration and drying: vacuum drying the modified PVB solution after washing until the moisture content is less than 5%;

[0044] 4) Dissolving: Dissolving 12 parts of the dried modified PVB into 75 parts of the composite organic solvent by mass to obtain a modified PVB coating solution;

[0045] Wherein, the composite organic solvent is composed of 20 parts of anhydrous ethanol, 20 parts of propylene glycol methyl ether, 15 parts of dimethyl acetal, and 20 parts of ethyl acetate (by mass);

[0046] 5) Preparation of cleaning film: The modified PVB coating solution is coated on the surface of the instrument and dried at room temperature for 24 hours to form a modified PVB peelable optical cleaning film.

[0047] The stain removal effect of the modified PVB peelable optical cleaning film and the existing PVB under an optical microscope is as follows Figure 2 shown.

[0048] like Figure 2 As shown, the contaminated samples are not coated with the existing PVB and the modified PVB coating solution of the present invention on the left side, and are coated with the existing PVB and the modified PVB coating solution of the present invention on the right side, and are peeled off from the substrate surface after drying. It can be seen from the figure that the existing PVB still has a small amount of contaminants remaining on the right side, and has not been completely peeled off, while the modified PVB coating solution of the present invention has basically completely peeled off the contaminants, and no residual contaminants are seen.

[0049] Example 3

[0050] A method for preparing a modified PVB strippable optical cleaning film comprises the following steps:

[0051] 1) Synthesis of modified PVB solution:

[0052] The dried polyvinyl butyral ester and anhydrous tetrahydrofuran were uniformly stirred at a mass ratio of 1:20 to obtain a 5% PVB solution; triethylamine and perfluorooctanoyl chloride were successively added to the PVB solution, wherein the molar ratio of the triethylamine to the hydroxyl group in the PVB was 1:1.5, and the molar ratio of the perfluorooctanoyl chloride to the hydroxyl group in the PVB was 1:1.5, and then the mixture was reacted at 50° C. under a closed condition for 4 hours to obtain a modified PVB solution;

[0053] 2) Water washing: After cooling the modified PVB solution, add it dropwise into the stirred deionized water to precipitate the white filamentous modified PVB. After filtering, wash it with water for 3 times until the pH value of the solution reaches 7.0.

[0054] 3) Dehydration and drying: vacuum drying the modified PVB solution after washing until the moisture content is less than 5%;

[0055] 4) Dissolving: Dissolving 25 parts of the dried modified PVB into 75 parts of the composite organic solvent by mass to obtain a modified PVB coating solution;

[0056] Wherein, the composite organic solvent is composed of 30 parts of anhydrous ethanol, 20 parts of propylene glycol methyl ether, 10 parts of dimethyl acetal, and 15 parts of ethyl acetate (by mass);

[0057] 5) Preparation of cleaning film: The modified PVB coating solution is coated on the surface of the instrument and dried at room temperature for 24 hours to form a modified PVB peelable optical cleaning film.

[0058] Table 2 Mechanical properties of samples

[0059] Sample name <![CDATA[Peeling strength (N / m -1 )]]> PVB-F 4.74 PVB 6.68

[0060] The 90° peel strength comparison diagram of the existing PVB and the modified PVB of the present invention is shown in the figure. Figure 3 shown.

[0061] like Figure 3 As shown, the peel strength of the modified PVB of the present invention is 4.74N / m -1 The existing PVB peel strength is 6.68N / m -1 The modified PVB of the present invention has lower peeling strength than the existing PVB, which means that it is easier to be peeled off from the surface of the substrate and is not easy to leave residue on the surface of the substrate.

Claims

1. A method for preparing a modified PVB strippable optical cleaning film, characterized in that: The following steps are involved: 1) Preparation of modified PVB solution: In a 5% to 10% PVB solution, triethylamine and perfluorooctanoyl chloride are added successively, the molar ratio of triethylamine to hydroxyl in PVB is 1:1.2 to 1.5, and the molar ratio of perfluorooctanoyl chloride to hydroxyl in PVB is 1:1.2 to 1.5, and then reacted at 25 to 60° C. under closed conditions for 0.5 to 6 hours to obtain a modified PVB solution; 2) Washing with water: After cooling the modified PVB solution, add it dropwise into the stirred water to precipitate the white filamentous modified PVB, filter it, and then wash it with water for 2 to 4 times until the pH value of the solution is 6.5 to 7.5; 3) Dehydration and drying: vacuum dry the washed modified PVB until the moisture content is less than 5%; 4) Dissolving: dissolving 10 to 25 parts of the dried modified PVB in 40 to 120 parts of the composite organic solvent by mass to obtain a modified PVB coating solution; 5) Preparation of cleaning film: The modified PVB coating solution is coated on the surface of the instrument, and after drying, a modified PVB strippable optical cleaning film is formed.

2. The method for preparing a modified PVB peelable optical cleaning film according to claim 1, characterized in that: The preparation method of the PVB solution in step 1) is: stirring and dissolving the dried polyvinyl butyral ester and anhydrous tetrahydrofuran in a mass ratio of 1:10-20 to obtain a 5%-10% PVB solution.

3. The method for preparing a modified PVB peelable optical cleaning film according to claim 1, characterized in that: The acetalization degree of the polyvinyl alcohol butyral ester is 68.0-80.0%, the residual hydroxyl content is greater than 20%, and the free acid is less than 0.05%.

4. The method for preparing a modified PVB peelable optical cleaning film according to claim 1, characterized in that: The molar ratio of the triethylamine in step 1) to the hydroxyl group in PVB is 1:1.35-1.5, and the molar ratio of the perfluorooctanoyl chloride to the hydroxyl group in PVB is 1:1.35-1.

5.

5. The method for preparing a modified PVB peelable optical cleaning film according to claim 1, characterized in that: In parts by mass, the composite organic solvent described in step 4) is composed of 10 to 30 parts of anhydrous ethanol, 10 to 40 parts of propylene glycol methyl ether, 10 to 20 parts of dimethyl acetal, and 10 to 30 parts of ethyl acetate.

6. The method for preparing a modified PVB peelable optical cleaning film according to claim 1, characterized in that: Step 5) The drying is carried out at a temperature of 25-45° C. for 0.5-24 hours.

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