Preparation method of dry film

Abstract

The invention discloses a preparation method of a dry film, and belongs to the technical field of medical films. The technical problems that in the prior art, a coloring agent adopted by a dry film is poor in color changing effect, and an adopted latex solution adhesive is poor in film forming property are solved. The preparation method of the dry film comprises the following steps: coating a PET (Polyethylene Terephthalate) base material with a modified SBR (Styrene Butadiene Rubber) latex solution to form a coating; the coating is coated with a photosensitive layer material to form a combined structure; drying and curing the combined structure, and laminating a polyurethane film to prepare a dry film; and the photosensitive layer material comprises thermosensitive dye microcapsules, a color developing agent and the like. According to the thermosensitive dye microcapsule, an intermediate A and 6, 7-dihydroxy-3-[(Z)-1-hydroxy-3-ketobutyl-1-alkenyl]-4-oxo-2, 3-dihydrochromene-5-carboxylic acid are subjected to a reaction, and a colored dye is synthesized; the prepared dry film has the advantages of being good in color changing effect, good in thermal performance and low in haze degree.

Description

Technical Field

[0001] The present invention relates to the technical field of medical films, in particular to a method for preparing dry films. Background Art

[0002] Medical imaging used to use X-ray film as the photosensitive material, resulting in only analog image information. Today, not only are X-ray projection photography used, but computed tomography and magnetic resonance imaging are also being used to generate digital image information and output it. Consequently, dry imaging film, the medium for digital information output in medical institutions, is becoming increasingly important. Among dry non-laser imaging technologies currently in use are dry flux thermal imaging, thermal dye sublimation, and direct thermal imaging.

[0003] Fluorans, as thermochromic compounds and solid acid developers, melt upon exposure to heat, producing a color-developing reaction. Consequently, these functional pigments are widely used as pressure- and heat-sensitive dyes. However, designing fluoran dyes and applying them to dry film with good color-changing properties and low color-changing temperatures remains a pressing technical challenge.

[0004] In addition, during the dry film preparation process, certain adhesives are often used to bond the substrate and the photosensitive layer material; after the polymer film is coated with the adhesive, the performance of the photosensitive layer material and the film performance need to be ensured; how to design the adhesive emulsion components to improve the film-forming properties of the photosensitive material and maintain good image preservation is also a technical problem that needs to be solved urgently.

[0005] In view of the technical defects in this aspect, a solution is now proposed. Summary of the Invention

[0006] The object of the present invention is to provide a method for preparing a dry film, which is used to solve the technical problems in the prior art that the dry film adopts a poor color change effect of a dye and a poor film-forming property of an adopted latex adhesive.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] A method for preparing a dry film comprises the following steps:

[0009] A modified SBR latex is coated on a PET substrate to form a coating; a photosensitive layer material is coated on the coating to form a composite structure; the composite structure is dried and cured at 60-180°C for 20-30 minutes, and a polyurethane film is laminated on the surface to prepare a dry film;

[0010] The photosensitive layer material comprises thermosensitive dye microcapsules, a developer, a sensitizer and a polymer matrix.

[0011] Furthermore, the preparation method of the modified SBR latex comprises the following steps:

[0012] A1 and 4,4'-bischloromethyl biphenyl are added to a dichloroethane solvent to obtain a 4,4'-bischloromethyl biphenyl solution; styrene-divinylbenzene copolymer and tin tetrachloride are then added to the 4,4'-bischloromethyl biphenyl solution, the temperature is raised to 70-80°C, and the mixture is reacted at this temperature for 5-8 hours to obtain a product; the product is subjected to a post-processing process to prepare a modified monomer B;

[0013] Using tin tetrachloride as a catalyst, the chloromethyl group of 4,4'-bischloromethylbiphenyl reacts with styrene-divinylbenzene copolymer to produce an alkylation reaction, thereby preparing a modified monomer B.

[0014] A2. Methyl methacrylate, modified monomer B, polymer emulsifier, polymerization initiator, chain transfer agent and solvent are mixed and reacted at 65-75° C. for 60-100 min under an inert gas atmosphere to obtain a reaction product; a stabilizer and a preservative are added to the reaction product and mixed to obtain a modified SBR latex.

[0015] SBR latex is obtained by emulsion polymerization of methyl methacrylate and modified monomer B. In addition to the monomers, additives such as polymer emulsifiers and chain transfer agents are also required. Additives such as dispersion stabilizers and preservatives are also added to the modified SBR latex to ensure the stability of the dry film applied with the modified SBR latex. The synthesized modified SBR latex can be used as a binder and film-forming aid.

[0016] Furthermore, the usage ratio of 4,4'-bischloromethylbiphenyl and solvent is 2.5-5g:50-60mL; the usage ratio of styrene-divinylbenzene copolymer, tin tetrachloride and 4,4'-bischloromethylbiphenyl solution is 5-10g:0.3-0.5g:52-65mL.

[0017] Furthermore, in step A2, the weight ratio of methyl methacrylate, modified monomer B, polymerization emulsifier, polymerization initiator, chain transfer agent, solvent, stabilizer and preservative is 20-30:30-50:3-5:0.3-0.5:1.5-2.5:200-300:0.5-0.8:0.05-0.1.

[0018] Furthermore, the preparation method of the thermosensitive dye microcapsules comprises the following steps:

[0019] B1, triphenylethylene bromide, methoxyphenylboric acid, sodium carbonate, deionized water, toluene and triphenylphosphine are mixed to obtain a reaction system; the reaction system is placed under an inert gas atmosphere and refluxed at 100-110° C. for 4-5 hours to obtain intermediate A;

[0020] The structural formula of intermediate A is as follows:

[0021]

[0022] B2, intermediate A and 6,7-dihydroxy-3-[(Z)-1-hydroxy-3-ketobut-1-enyl]-4-oxo-2,3-dihydrochromene-5-carboxylic acid are mixed and refluxed at 60-70° C. for 3-4 hours to obtain a product; the product is subjected to post-processing to obtain a colored dye; the colored dye is mixed with octadecylphosphoric acid to synthesize a dye;

[0023] Using triphenylphosphine as a catalyst, triphenylethylene bromide and methoxyphenylboronic acid undergo a Suzuki coupling reaction to synthesize solid intermediate A; intermediate A and 6,7-dihydroxy-3-[(Z)-1-hydroxy-3-ketobut-1-enyl]-4-oxo-2,3-dihydrochromene-5-carboxylic acid further undergo an addition polymerization reaction to synthesize a colored dye.

[0024] B3. Add the dye to toluene, heat to 50-60°C, and stir at this temperature until the dye is completely dissolved to obtain a core material solution; add the core material solution to the polyvinyl alcohol aqueous solution and stir at high speed to obtain an emulsion; add an initiator and methyl methacrylate to the emulsion and polymerize to obtain a microcapsule emulsion; centrifuge, wash, and dry the microcapsule emulsion to prepare thermosensitive dye microcapsules.

[0025] Polyvinyl alcohol and methyl methacrylate are used as unsaturated monomers, which undergo free radical addition polymerization to form microcapsules that encapsulate the core material dye.

[0026] Furthermore, in step B1, the amount ratio of brominated triphenylethylene, methoxyphenylboric acid, sodium carbonate, deionized water, toluene and triphenylphosphine is 3.35-6.70g:1.4-2.8g:3-5g:30mL:50mL:0.15-0.25g; in step B2, the amount ratio of intermediate A and 6,7-dihydroxy-3-[(Z)-1-hydroxy-3-ketobut-1-enyl]-4-oxo-2,3-dihydrochromene-5-carboxylic acid is 85-90g:3-6g; the post-processing steps of the product include: extracting the product with dichloromethane to extract the organic phase; drying the organic phase with anhydrous sodium sulfate, and the obtained solid is the colored dye.

[0027] Furthermore, in step B3, the ratio of the dye to toluene is 1.5-2.5 g:30-40 mL; the concentration of the polyvinyl alcohol aqueous solution is 25-35% wt, and the ratio of the polyvinyl alcohol aqueous solution to the core material solution is 50-60 mL:30-40 mL; the high-speed stirring speed is 6000-7000 r / min, and the high-speed stirring time is 15-25 min; the ratio of the emulsion, initiator and methyl methacrylate is 80-90 mL:0.3-0.5 g:10-15 g.

[0028] Furthermore, the coating thickness of the modified SBR latex on the PET substrate is 0.5-1 μm; the preparation method of the photosensitive layer material is as follows: according to parts by weight, 5-10 parts of thermosensitive dye microcapsules, 20-30 parts of developer, 10-15 parts of sensitizer and 15-20 parts of polymer matrix are mixed to obtain the photosensitive layer material; the coating amount of the photosensitive layer material is 3-5 g / m 2 The drying and curing time of the combined structure is 20-30 minutes, and the lamination pressure is 0.3-0.5MPa.

[0029] As another aspect of the present invention, a dry film is prepared by a dry film preparation method.

[0030] The present invention has the following beneficial effects:

[0031] 1. The dry film synthesized in the present invention comprises the following components: a PET substrate as a support; an adhesive-modified SBR latex is applied to the surface of the PET substrate to form a coating; a photosensitive layer material is uniformly and densely distributed on the coating layer with a developer and thermosensitive dye microcapsules; a polyurethane film is then placed on the photosensitive layer as a protective layer, and the film is dried and cured to form the dry film. The present invention uses the prepared modified SBR latex as an adhesive; styrene-divinylbenzene copolymer is crosslinked with 4,4'-bis(chloromethyl)biphenyl to form a modified monomer B with resin-like properties; and modified monomer B is reacted with methyl methacrylate to produce a toughened modified SBR latex with excellent mechanical properties. The modified SBR latex monomer has a high molecular weight and a high glass transition temperature, which facilitates thermal development of dry film. Furthermore, the synthesized modified SBR latex does not react with latex additives, thereby preventing fogging on dry imaging films and ensuring high-quality imaging.

[0032] 2. The thermosensitive dye is encapsulated in a microcapsule formed by a polymer. Under the action of heat, the microcapsule breaks, and the color developer reacts with the thermosensitive dye inside the microcapsule to form a color-developing dye; brominated triphenylethylene and methoxyphenylboronic acid are used to synthesize intermediate A; intermediate A reacts with 6,7-dihydroxy-3-[(Z)-1-hydroxy-3-ketobut-1-enyl]-4-oxo-2,3-dihydrochromene-5-carboxylic acid to synthesize a colored dye with a lactone ring. When the colored dye comes into contact with the color developer (proton donor), the lactone ring is opened, and the SP of the central carbon atom is converted to a color-developing dye. 3 Hybrid orbitals converted to SP 2 The hybrid orbital forms a planar π-conjugated system in the dye molecules, which increases the electron overlap efficiency and reduces the molecular excitation energy, causing its maximum absorbance to red-shift to the visible light region, thus producing a color development effect. The organic dye synthesized by the present invention has the advantages of large color density, wide chromatographic range, and good stability. DETAILED DESCRIPTION

[0033] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] The styrene-divinylbenzene copolymer used in Examples 1-3 of the present invention was purchased from Jiangsu Secosaisi Resin Co., Ltd., and the cross-linking degree was 1%;

[0035] The structural formula of 6,7-dihydroxy-3-[(Z)-1-hydroxy-3-ketobut-1-enyl]-4-oxo-2,3-dihydrochromene-5-carboxylic acid used in Example 4-6 of the present invention is as follows:

[0036]

[0037] The PET particles used in Examples 7-9 of the present invention were purchased from Yangzhou Xindong Trade Development Co., Ltd. and the brand is bg80.

[0038] Example 1

[0039] This embodiment provides a method for preparing a modified SBR latex for dry film, comprising the following steps:

[0040] A1. Add 2.5 g of 4,4'-bischloromethylbiphenyl to 50 mL of dichloroethane to obtain a 4,4'-bischloromethylbiphenyl solution. Then, add 5 g of styrene-divinylbenzene copolymer and 0.3 g of tin tetrachloride to 52 mL of the 4,4'-bischloromethylbiphenyl solution. Heat to 70°C and react at this temperature for 5 hours to obtain the product. The product is washed sequentially with acetone, 0.5 mol / L HCl solution, and deionized water, and then vacuum-dried at 70°C to a constant weight to prepare modified monomer B.

[0041] A2. Mix 20 parts by weight of methyl methacrylate, 30 parts of modifying monomer B, 3 parts of abietic acid (polymeric emulsifier), 0.3 parts of potassium persulfate (polymerization initiator), 1.5 parts of dodecanethiol (chain transfer agent), and 200 parts of dichloromethane (solvent). Under a nitrogen atmosphere, react at 65°C for 60 minutes to obtain a reaction product. Add 0.5 parts of sodium carboxymethyl cellulose (stabilizer) and 0.05 parts of potassium sorbate (preservative) to the reaction product and mix thoroughly to prepare a modified SBR latex.

[0042] Example 2

[0043] This embodiment provides a method for preparing a modified SBR latex for dry film, comprising the following steps:

[0044] A1. Add 3.5 g of 4,4'-bischloromethylbiphenyl to 55 mL of dichloroethane to obtain a 4,4'-bischloromethylbiphenyl solution. Then, add 8 g of styrene-divinylbenzene copolymer and 0.4 g of tin tetrachloride to the 55 mL 4,4'-bischloromethylbiphenyl solution. Heat the mixture to 75°C and react at this temperature for 6 hours to obtain the product. The product is washed sequentially with acetone, 0.6 mol / L HCl solution, and deionized water, and then vacuum-dried at 75°C to a constant weight to obtain modified monomer B.

[0045] A2. Mix 25 parts by weight of methyl methacrylate, 35 parts of modifying monomer B, 4 parts of abietic acid (polymeric emulsifier), 0.5 parts of potassium persulfate (polymerization initiator), 2 parts of dodecanethiol (chain transfer agent), and 250 parts of dichloromethane (solvent). Under a nitrogen atmosphere, react at 70°C for 80 minutes to obtain a reaction product. Add 0.6 parts of sodium carboxymethyl cellulose (stabilizer) and 0.08 parts of potassium sorbate (preservative) to the reaction product and mix thoroughly to prepare a modified SBR latex.

[0046] Example 3

[0047] This embodiment provides a method for preparing a modified SBR latex for dry film, comprising the following steps:

[0048] A1. Add 5 g of 4,4'-bischloromethylbiphenyl to 60 mL of dichloroethane to obtain a 4,4'-bischloromethylbiphenyl solution. Then, add 10 g of styrene-divinylbenzene copolymer and 0.5% tin tetrachloride to 65 mL of the 4,4'-bischloromethylbiphenyl solution. Heat to 80°C and react at this temperature for 8 hours to obtain the product. The product is washed sequentially with acetone, 1 mol / L HCl solution, and deionized water, and then vacuum dried at 80°C to a constant weight to prepare modified monomer B.

[0049] A2. Mix 30 parts by weight of methyl methacrylate, 50 parts of modified monomer B, 5 parts of abietic acid (polymeric emulsifier), 0.5 parts of potassium persulfate (polymerization initiator), 2.5 parts of dodecanethiol (chain transfer agent), and 300 parts of dichloromethane (solvent). Under a nitrogen atmosphere, react at 75°C for 100 minutes to obtain a reaction product. Add 0.8 parts of sodium carboxymethyl cellulose (stabilizer) and 0.1 parts of potassium sorbate (preservative) to the reaction product and mix thoroughly to prepare a modified SBR latex.

[0050] Example 4

[0051] This embodiment provides a method for preparing thermosensitive dye microcapsules for dry film, comprising the following steps:

[0052] B1, 3.35 g of bromotriphenylethylene, and 1.4 g of methoxyphenylboronic acid were added to a 100 mL round-bottom flask. Then, 3 g of sodium carbonate, 30 mL of deionized water, 50 mL of toluene, and 0.15 g of triphenylphosphine were added and mixed to obtain a reaction system. The three-necked round-bottom flask was placed under a nitrogen atmosphere and refluxed at 100°C for 4 h to obtain Intermediate A.

[0053] B2. Add 3 g of 6,7-dihydroxy-3-[(Z)-1-hydroxy-3-ketobut-1-enyl]-4-oxo-2,3-dihydrochromene-5-carboxylic acid to 85 g of Intermediate A. Continue the reaction at reflux at 60°C for 3 hours to obtain the product. Extract the product with dichloromethane, and then dry the organic phase over anhydrous sodium sulfate to obtain a solid, which is the synthesized colored dye. Mix the colored dye and octadecylphosphoric acid in a 1:1 mass ratio to synthesize the dye.

[0054] B3. Add 1.5 g of the dye to 30 mL of toluene, heat to 50°C, and stir at this temperature until the dye is completely dissolved. Then cool to room temperature to prepare a core material solution. Prepare 50 mL of a 25% wt aqueous solution of polyvinyl alcohol. Add 30 mL of the core material solution to the polyvinyl alcohol aqueous solution and stir at 6000 rpm for 15 minutes to obtain an emulsion. Add 0.3 g of the initiator ammonium persulfate and 10 g of methyl methacrylate to 80 mL of the emulsion. Polymerize at 65°C for 4 hours to obtain a microcapsule emulsion. Centrifuge the microcapsule emulsion, wash, and dry to prepare thermosensitive dye microcapsules.

[0055] Example 5

[0056] This embodiment provides a method for preparing thermosensitive dye microcapsules for dry film, comprising the following steps:

[0057] B1, 5 g of bromotriphenylethylene, and 2.1 g of methoxyphenylboronic acid were added to a 100 mL round-bottom flask. Then, 4 g of sodium carbonate, 30 mL of deionized water, 50 mL of toluene, and 0.2 g of triphenylphosphine were added and mixed to obtain a reaction system. The three-necked round-bottom flask was placed under a nitrogen atmosphere and refluxed at 105°C for 4.5 h to obtain Intermediate A.

[0058] B2. Add 5 g of 6,7-dihydroxy-3-[(Z)-1-hydroxy-3-ketobut-1-enyl]-4-oxo-2,3-dihydrochromene-5-carboxylic acid to 88 g of Intermediate A. Continue the reaction at reflux at 65°C for 3.5 hours to obtain the product. Extract the product with dichloromethane, and then dry the organic phase over anhydrous sodium sulfate to obtain a solid, which is the synthesized colored dye. Mix the colored dye and octadecylphosphoric acid in a mass ratio of 1.5:1 to synthesize the dye.

[0059] B3. Add 2g of dye to 35mL of toluene, heat to 55°C, and stir at this temperature until the dye is completely dissolved. Then cool to room temperature to prepare a core material solution. Prepare 55mL of a 30% wt. polyvinyl alcohol aqueous solution. Add 35mL of the core material solution to the polyvinyl alcohol aqueous solution and stir at 6500 rpm for 20 minutes to obtain an emulsion. Add 0.4g of initiator ammonium persulfate and 12g of methyl methacrylate to 84mL of the emulsion. Polymerize at 70°C for 4.5 hours to obtain a microcapsule emulsion. Centrifuge the microcapsule emulsion, wash, and dry to prepare thermosensitive dye microcapsules.

[0060] Example 6

[0061] This embodiment provides a method for preparing thermosensitive dye microcapsules for dry film, comprising the following steps:

[0062] B1, 6.70 g of bromotriphenylethylene, and 2.8 g of methoxyphenylboronic acid were added to a 100 mL round-bottom flask. 5 g of sodium carbonate, 30 mL of deionized water, 50 mL of toluene, and 0.25 g of triphenylphosphine were added and mixed to obtain a reaction system. The three-necked round-bottom flask was placed under a nitrogen atmosphere and refluxed at 110°C for 5 h to obtain Intermediate A.

[0063] B2. Add 6 g of 6,7-dihydroxy-3-[(Z)-1-hydroxy-3-ketobut-1-enyl]-4-oxo-2,3-dihydrochromene-5-carboxylic acid to 90 g of Intermediate A. Continue the reaction at reflux at 70°C for 4 hours to obtain the product. Extract the product with dichloromethane, and then dry the organic phase over anhydrous sodium sulfate to obtain a solid, which is the synthesized colored dye. Mix the colored dye and octadecylphosphoric acid in a mass ratio of 2:1 to synthesize the dye.

[0064] B3. Add 2.5 g of the dye to 40 mL of toluene, heat to 60°C, and stir at this temperature until the dye is completely dissolved. Then cool to room temperature to prepare a core material solution. Prepare 60 mL of a 35% wt aqueous solution of polyvinyl alcohol. Add 40 mL of the core material solution to the polyvinyl alcohol aqueous solution and stir at 7000 rpm for 25 minutes to obtain an emulsion. Add 0.5 g of the initiator ammonium persulfate and 15 g of methyl methacrylate to 90 mL of the emulsion. Polymerize at 75°C for 5 hours to obtain a microcapsule emulsion. Centrifuge the microcapsule emulsion, wash, and dry to prepare thermosensitive dye microcapsules.

[0065] Example 7

[0066] This embodiment provides a method for preparing a dry film, comprising the following steps:

[0067] S1. PET pellets were melt-extruded at a temperature of 75°C to obtain a PET raw material; the PET raw material was naturally cooled to room temperature and then cut into pieces of 10 cm × 10 cm × 0.1 mm in size to obtain a PET sample; the PET sample was added to a dedicated stretching machine, heated to 80°C, and stretched to 3 times its original length to obtain a PET substrate.

[0068] S2. The modified SBR latex prepared in Example 1 was coated on the PET substrate to obtain a coating with a coating thickness of 0.5 μm. 5 parts of the thermosensitive dye microcapsules prepared in Example 4, 20 parts of the developer bisphenol A, 10 parts of the sensitizer stearamide and 15 parts of the polymer matrix polyvinyl alcohol were mixed by weight to obtain a photosensitive layer material. The photosensitive layer material was set on the coating and micro-gravure coating was used with a coating amount of 3 g / m 2, obtaining a combined structure; the combined structure was dried and cured at 160°C for 20 minutes, and then a polyurethane film was laminated on its surface using a pressure roller with a pressure of 0.3 MPa to form a protective layer, and finally a dry film was prepared.

[0069] Example 8

[0070] This embodiment provides a method for preparing a dry film, comprising the following steps:

[0071] S1. PET pellets were melt-extruded at a temperature of 80°C to obtain a PET raw material; the PET raw material was naturally cooled to room temperature and then cut into pieces of 10 cm × 10 cm × 0.2 mm in size to obtain a PET sample; the PET sample was added to a dedicated stretching machine, heated to 90°C, and stretched to 4 times its original length to obtain a PET substrate.

[0072] S2. The modified SBR latex prepared in Example 2 was coated on the PET substrate to obtain a coating with a coating thickness of 0.8 μm. 8 parts of the thermosensitive dye microcapsules prepared in Example 5, 25 parts of the developer bisphenol A, 12 parts of the sensitizer stearamide and 18 parts of the polymer matrix polyvinyl alcohol were mixed by weight to obtain a photosensitive layer material. The photosensitive layer material was set on the coating and micro-gravure coating was used with a coating amount of 4 g / m 2 , obtaining a combined structure; the combined structure was dried and cured at 170°C for 25 minutes, and then a polyurethane film was laminated on its surface using a pressure roller with a pressure of 0.4 MPa to form a protective layer, and finally a dry film was prepared.

[0073] Example 9

[0074] This embodiment provides a method for preparing a dry film, comprising the following steps:

[0075] S1. PET pellets are melt-extruded at a temperature of 85°C to obtain a PET raw material; the PET raw material is naturally cooled to room temperature and then cut into pieces of 10 cm × 10 cm × 0.1 mm in size to obtain a PET sample; the PET sample is added to a dedicated stretching machine, heated to 100°C, and stretched to 4 times its original length to obtain a PET substrate.

[0076] S2. The modified SBR latex prepared in Example 3 was coated on the PET substrate to obtain a coating with a coating thickness of 1 μm. According to parts by weight, 10 parts of the thermosensitive dye microcapsules prepared in Example 6, 30 parts of the developer bisphenol A, 115 parts of the sensitizer stearamide and 20 parts of the polymer matrix polyvinyl alcohol were mixed to obtain a photosensitive layer material. The photosensitive layer material was set on the coating and micro-gravure coating was used with a coating amount of 5 g / m 2, obtaining a combined structure; the combined structure was dried and cured at 180°C for 30 minutes, and then a polyurethane film was laminated on its surface using a pressure roller with a pressure of 0.5 MPa to form a protective layer, and finally a dry film was prepared.

[0077] Comparative Example 1

[0078] The difference between this comparative example and Example 9 is that when preparing the modified SBR latex, the modified monomer B is replaced by styrene of equal mass.

[0079] Comparative Example 2

[0080] The difference between this comparative example and Example 9 is that, when preparing the thermosensitive dye microcapsules, step B2 is omitted, and the preparation process of the dye specifically includes the following steps:

[0081] 90 g of intermediate A was extracted with dichloromethane to obtain an organic phase, which was then dried over anhydrous sodium sulfate to obtain a solid, which was the synthesized colored dye. The colored dye and octadecylphosphoric acid were mixed in a mass ratio of 2:1 to synthesize a dye.

[0082] Comparative Example 3

[0083] The difference between this comparative example and Example 9 is that step B1 and step B2 are omitted, and the synthesized dye is replaced by 3-diethylamino-7-(2'-chloroanilino)fluoran of the same mass.

[0084] Performance testing:

[0085] 1. The color change temperatures of the dry films prepared in Examples 7-9 and Comparative Examples 1-3 were measured using a micro melting point meter.

[0086] 2. The dry films prepared in Examples 7-9 and Comparative Examples 1-3 were heated at 50°C for 90 seconds, then naturally cooled to room temperature and observed for color change. The color change was evaluated based on two criteria: the significance of the color change (dark, relatively dark, relatively light, and light) and the speed of the color change (fast, relatively fast, relatively slow, and slow).

[0087] 3. The glass transition temperatures of the modified SBR latex in the dry films prepared in Examples 7-9 and Comparative Examples 1-3 were tested in turn.

[0088] 4. The fog values ​​of the dry films prepared in Examples 7-9 and Comparative Examples 1-3 were tested in sequence. The specific test results are shown in Table 1:

[0089] Table 1. Performance test data of samples

[0090]

[0091]

[0092] Data Analysis: A comparative analysis of the data in Table 1 shows that the dry films prepared in Examples 7-9 of the present invention all have relatively low color change temperatures; however, the dry films prepared in Comparative Examples 2 and 3 have relatively high color change temperatures. The dry films prepared in Examples 7-9 of the present invention exhibit excellent color change effects, particularly those prepared in Examples 7-9, which exhibit rapid color development and high color concentration. However, in Comparative Example 2, 6,7-dihydroxy-3-[(Z)-1-hydroxy-3-ketobut-1-enyl]-4-oxo-2,3-dihydrochromene-5-carboxylic acid was not added during the preparation of the thermosensitive dye microcapsules. This prevented the formation of a lactone ring, reduced planar co-π systems, decreased electron overlap efficiency, and low color density, resulting in poor color development. Comparative Example 3, in which the commercially available 3-diethylamino-7-(2'-chloroanilino)fluoran was substituted for the synthesized dye, exhibited inferior color development to that of the dye prepared in Example 9, demonstrating that the dye prepared in accordance with the present invention exhibits superior dyeing effects.

[0093] The dry films prepared in Examples 7-9 of the present invention all have high glass transition temperatures and excellent thermal properties of the polymers. The high glass transition temperature of the prepared modified SBR latex facilitates the dry film's use of thermal energy for image development. However, in Comparative Example 1, styrene was used in place of the modified monomer B in the preparation of the modified SBR latex; the resulting polymer had a reduced molecular weight and poor adhesion properties, manifested as a lower glass transition temperature and increased haze value for the synthesized latex.

[0094] The above content is merely an example and explanation of the structure of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described, or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they shall fall within the scope of protection of the present invention.

[0095] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0096] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to specific embodiments. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a dry film, characterized in that: The following steps are involved: A modified SBR latex is applied to a PET substrate to form a coating; a photosensitive layer material is applied to the coating to form a composite structure; the composite structure is dried and cured at 60-180°C, and a polyurethane film is laminated on the surface to prepare a dry film; The photosensitive layer material comprises thermosensitive dye microcapsules, a developer, a sensitizer and a polymer matrix.

2. A dry film preparation method according to claim 1, characterized in that: The preparation method of the modified SBR latex comprises the following steps: A1 and 4,4'-bischloromethyl biphenyl are added to dichloroethane to obtain a 4,4'-bischloromethyl biphenyl solution; styrene-divinylbenzene copolymer and tin tetrachloride are then added to the 4,4'-bischloromethyl biphenyl solution, the temperature is raised to 70-80°C, and the mixture is reacted at this temperature for 5-8 hours to obtain a product; the product is subjected to post-processing to prepare a modified monomer B; A2. Methyl methacrylate, modified monomer B, polymer emulsifier, polymerization initiator, chain transfer agent and solvent are mixed and reacted at 65-75° C. for 60-100 min under an inert gas atmosphere to obtain a reaction product; a stabilizer and a preservative are added to the reaction product and mixed to obtain a modified SBR latex.

3. A dry film preparation method according to claim 2, characterized in that: In step A1, the ratio of 4,4'-bischloromethylbiphenyl to solvent is 2.5-5 g:50-60 mL; the ratio of styrene-divinylbenzene copolymer, tin tetrachloride and 4,4'-bischloromethylbiphenyl solution is 5-10 g:0.3-0.5 g:52-65 mL.

4. The method for preparing a dry film according to claim 2, wherein: In step A1 and step A2, the weight ratio of methyl methacrylate, modified monomer B, polymerization emulsifier, polymerization initiator, chain transfer agent, solvent, stabilizer and preservative is 20-30:30-50:3-5:0.3-0.5:1.5-2.5:200-300:0.5-0.8:0.05-0.

1.

5. The method for preparing a dry film according to claim 1, wherein: The preparation method of the thermosensitive dye microcapsule comprises the following steps: B1, triphenylethylene bromide, methoxyphenylboric acid, sodium carbonate, deionized water, toluene and triphenylphosphine are mixed to obtain a reaction system; the reaction system is placed under an inert gas atmosphere and refluxed at 100-110° C. for 4-5 hours to obtain intermediate A; B2, intermediate A and 6,7-dihydroxy-3-[(Z)-1-hydroxy-3-ketobut-1-enyl]-4-oxo-2,3-dihydrochromene-5-carboxylic acid are mixed and refluxed at 60-70° C. for 3-4 hours to obtain a product; the product is subjected to post-processing to obtain a colored dye; the colored dye is mixed with octadecylphosphoric acid to synthesize a dye; B3. Add the dye to toluene, heat to 50-60°C, and stir at this temperature until the dye is completely dissolved to obtain a core material solution; add the core material solution to the polyvinyl alcohol aqueous solution and stir at high speed to obtain an emulsion; add an initiator and methyl methacrylate to the emulsion and polymerize to obtain a microcapsule emulsion; centrifuge, wash, and dry the microcapsule emulsion to prepare thermosensitive dye microcapsules.

6. A dry film preparation method according to claim 5, characterized in that: In step B1, the amount ratio of bromotriphenylethylene, methoxyphenylboric acid, sodium carbonate, deionized water, toluene and triphenylphosphine is 3.35-6.70 g:1.4-2.8 g:3-5 g:30 mL:50 mL:0.15-0.25 g; in step B2, the amount ratio of intermediate A and 6,7-dihydroxy-3-[(Z)-1-hydroxy-3-ketobut-1-enyl]-4-oxo-2,3-dihydrochromene-5-carboxylic acid is 85-90 g:3-6 g; the post-processing steps of the product include: extracting the product with dichloromethane, extracting the organic phase; and drying the organic phase with anhydrous sodium sulfate to obtain a solid, which is a colored dye.

7. The method for preparing a dry film according to claim 5, characterized in that: In step B3, the amount ratio of the dye and toluene is 1.5-2.5g:30-40mL; the concentration of the polyvinyl alcohol aqueous solution is 25-35%wt, and the amount ratio of the polyvinyl alcohol aqueous solution and the core material solution is 50-60mL:30-40mL; the high-speed stirring speed is 6000-7000r / min, and the high-speed stirring time is 15-25min; the amount ratio of the emulsion, initiator and methyl methacrylate is 80-90mL:0.3-0.5g:10-15g.

8. The method for preparing a dry film according to claim 1, wherein: The thickness of the coating of the modified SBR latex on the PET substrate is 0.5-1 μm. The preparation method of the photosensitive layer material is as follows: according to parts by weight, 5-10 parts of thermosensitive dye microcapsules, 20-30 parts of developer, 10-15 parts of sensitizer and 15-20 parts of polymer matrix are mixed to obtain the photosensitive layer material; the coating amount of the photosensitive layer material is 3-5 g / m 2 The drying and curing time of the combined structure is 20-30 minutes, and the lamination pressure is 0.3-0.5MPa.

9. A dry film, characterized in that: The dry film is prepared by the dry film preparation method according to any one of claims 1 to 8.

Images