Laser medical film and preparation method thereof

Abstract

The invention discloses a laser medical film and a preparation method thereof. The laser medical film comprises a polyester base, an antistatic layer is provided on the reverse side of the polyester base, and a laser ink-absorbing layer is provided on the front side; the material of the polyester base is polyethylene terephthalate, the effective component in the antistatic layer is a cationic quaternary ammonium salt, and the laser ink-absorbing layer contains polymethyl methacrylate dispersion and water-based acrylic paint. The invention only requires one laser ink-absorbing layer coating liquid, and by replacing different PET base types, a variety of corresponding laser medical films can be produced, the operation is simple, the production efficiency is high, the production cycle of the medical film is shortened, the output per unit time is increased, and the invention is suitable for industrial production.

Description

Technical Field

[0001] The invention belongs to the technical field of medical films, and in particular relates to a laser medical film and a preparation method thereof. Background Art

[0002] With the continuous upgrading of the manufacturing technology of digital medical imaging equipment and its widespread application in medical institutions at all levels, as well as the innovation and development of printing technology, medical films have fully entered the digital printing stage. At present, the mainstream solution on the market is to use inkjet printing to print medical images onto PET substrate films coated with ink-absorbing coatings. However, inkjet printing is extremely slow, and the quality of ink varies. It is easily oxidized under the action of natural light and heat, causing the image to fade. Laser printing is fast and the toner is not easy to fade. If it can be applied to the output field of medical films, it is very ideal. However, the existing coating structure and composition of laser medical films can only meet the production of specific PET base films. If different types of laser medical films need to be produced at the same time, it is necessary to switch to coating liquids of different compositions for production, which will result in a longer film production cycle and poor versatility of film PET films.

[0003] A Chinese patent with publication number CN 106965586 A discloses a medical blue laser printing film and a preparation method thereof. The medical blue laser printing film comprises a transparent PET substrate; a laser printing coating is arranged on the front side of the transparent PET substrate, and a blue antistatic layer is arranged on the back side; the preparation method comprises the following steps: step ①: preparation of laser printing coating paint; step ②: coating of laser printing coating: using slide extrusion coating, heating and drying with steam, the drying temperature reaches above 100°C; the coating dry basis thickness is 10 microns; step ③: preparation of blue antistatic layer coating: step ④: coating of blue antistatic layer: using slide extrusion coating, heating and drying with steam, the drying temperature reaches above 100°C; the coating dry basis thickness is 2-2.5 microns. The patent is suitable for high-resolution laser printing, anti-adhesion, low friction coefficient, anti-static, high adhesion, high gloss, blue transparent appearance, acid and alkali resistance, strong wear resistance, green and environmentally friendly, simple manufacturing method, suitable for mass production, but the coating of the patent has a long ink absorption time, low contrast, poor gloss, low resolution, and can only be applied to the production of specific blue film-based laser medical films. The Chinese patent with publication number CN113895163A discloses a PET medical film with clear imaging and a preparation method, including a PET film body, a protective layer is provided on the surface of the PET film body, a UV coating is provided on one side of the protective layer, a substrate is provided on one side of the UV coating, an inkjet adhesive layer is provided on one side of the substrate, a photosensitive emulsion layer is provided on one side of the inkjet adhesive layer, and an anti-halo electrostatic layer is provided on one side of the photosensitive emulsion layer. The medical film of this patent has the advantages of anti-static, no deformation of the film, intuitive diagnosis, no need for viewing lights, energy saving and eye protection, three-dimensional, color, and functional imaging - all are clear at a glance. However, this patent cannot be applied to laser printing, and the printed film has poor corrosion resistance, and one coating liquid can only be used for the production of one type of medical film PET base film. Summary of the invention

[0004] In order to solve the deficiencies in the prior art, the present invention aims to provide a laser medical film and a preparation method thereof. The laser medical film only needs one laser ink-absorbing layer coating liquid, and can produce a variety of corresponding laser medical films by directly replacing different PET film base types. The operation is simple, the production efficiency is high, and the output per unit time is increased.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A laser medical film comprises a polyester base, wherein an antistatic layer is arranged on the reverse side of the polyester base and a laser ink-absorbing layer is arranged on the front side; the polyester base is made of polyethylene terephthalate, the effective ingredient in the antistatic layer is a cationic quaternary ammonium salt, and the laser ink-absorbing layer contains a polymethyl methacrylate dispersion and a water-based acrylic paint.

[0007] Furthermore, the polyester base has a thickness T of 100-200 μm, a light transmittance P of 20-75%, a haze H of 1-93%, and a density D of 0.1-0.6.

[0008] Furthermore, the antistatic layer also contains auxiliary materials of isopropyl alcohol, polyethylene wax emulsion and deionized water.

[0009] Furthermore, based on the total mass of the laser ink-absorbing layer water-based acrylic coating liquid, the laser ink-absorbing layer contains the following components in mass percentage: 1% of polymethyl methacrylate particles with a diameter of 10 μm, 3% of polyvinyl alcohol solution, 28% of water-based acrylic emulsion, 2% of branched alkyl ester copolymer sodium salt wetting agent, 1.2% of polyethylene wax emulsion lubricant, and the remainder is water; the mass fraction of the polyvinyl alcohol solution is 10%, the degree of polymerization is 1700-1900, and the degree of alcoholysis is 88%; the mass fraction of the water-based acrylic emulsion is 45%.

[0010] Furthermore, a method for preparing the above laser medical film comprises the following steps:

[0011] (1) preparing an antistatic coating liquid: preparing a cationic quaternary ammonium salt surfactant, the mass of which accounts for 20% of the total amount of the antistatic coating liquid, preparing isopropyl alcohol, the mass of which accounts for 5% of the total amount of the antistatic coating liquid, preparing a polyethylene wax emulsion, the mass of which accounts for 5% of the total amount of the antistatic coating liquid, taking deionized water, the mass of which accounts for 70% of the total amount of the antistatic coating liquid, mixing the above-prepared solution with deionized water at room temperature, stirring at 300-500 r / min for 1-1.5 h to make the mixture uniformly mixed, and obtaining a water-soluble antistatic coating liquid for standby use;

[0012] (2) Preparing a dispersion liquid for a laser ink-absorbing layer: Weigh polymethyl methacrylate particles with a diameter of 10 μm and water in a weight ratio of 1:9, put them into a beaker, and stir at 1000-1500 r / min for 15-30 min until no precipitated particle aggregation layer is seen at the bottom of the beaker, thereby obtaining a dispersion liquid for a laser ink-absorbing layer, which is set aside;

[0013] (3) preparing a laser ink-absorbing layer coating liquid: weighing the polymethyl methacrylate dispersion prepared in step (2), the mass of which accounts for 10% of the total mass of the laser ink-absorbing layer coating liquid; preparing a 10% by mass percentage polyvinyl alcohol solution, the mass of which accounts for 3% of the total mass of the laser ink-absorbing layer coating liquid; preparing a 45% by mass percentage aqueous acrylic emulsion, the mass of which accounts for 28% of the total mass of the laser ink-absorbing layer coating liquid; preparing a branched alkyl ester copolymer sodium salt wetting agent, the mass of which accounts for 2% of the total mass of the laser ink-absorbing layer coating liquid; preparing a polyethylene wax emulsion lubricant, the mass of which accounts for 1.2% of the total mass of the laser ink-absorbing layer coating liquid; mixing the above-prepared solutions with water, stirring them thoroughly for 1-1.5 hours, and mixing them evenly to obtain a laser ink-absorbing layer coating liquid for later use;

[0014] (4) Coating: First, the polyester film base is subjected to corona treatment. Then, the prepared antistatic layer coating liquid and laser ink absorption layer coating liquid are subjected to static defoaming and filtration treatments in turn. Finally, the laser ink absorption layer coating liquid and the antistatic layer coating liquid are coated on the front and back sides of the corona treated polyester film base respectively by using a slide extrusion coating method.

[0015] (5) placing the polyester film base coated in step (4) into a tunnel drying device for drying to obtain a laser medical film.

[0016] Furthermore, in the step (4), the corona treatment is performed by applying high-frequency high-voltage electricity between two electrodes under normal pressure, first corona treating the back side of the polyester base and then corona treating the front side of the polyester base, and the corona conductivity is 320 S / m.

[0017] Furthermore, in the step (4), the antistatic layer coating liquid is directly filtered through a 200-mesh filter cloth; the laser ink-absorbing layer coating liquid is first filtered through a 20 μm filter bag and then placed in a static pot for standby use, and then filtered through a 10 μm filter element of the coating system during coating.

[0018] Furthermore, the environmental conditions for coating in step (4) are: temperature of 19-25° C. and humidity of 35-55%.

[0019] Furthermore, in the step (5), the thickness of the laser ink-absorbing layer coating on the front side of the polyester film base after drying is 10-15 μm; the thickness of the antistatic layer coating on the back side of the polyester film base after drying is 3-5 μm.

[0020] Furthermore, in step (5), the drying temperature is 75-80° C. and the drying time is 30-60 min.

[0021] Furthermore, the specific coating process in step (4) is as follows: after the back coating is first performed using a wire rod, it directly enters the back coating drying channel for drying, and then it is top-coated by slide extrusion coating and then enters the top coating drying channel for forming.

[0022] Polyester film is made of polyethylene terephthalate (PET) as raw material, extruded into thick sheets, and then biaxially stretched to form a film material. It is a colorless, transparent, and glossy plastic film (additive particles can be added to give it color). The common transparent polyester PET film without additive particles has excellent mechanical properties, high rigidity, hardness and toughness, puncture resistance, friction resistance, high and low temperature resistance, chemical resistance, oil resistance, printability, good air tightness and fragrance retention. White polyester PET film and blue polyester PET film show their respective color differences because of the different colors of the additive particles added to each.

[0023] Compared with the prior art, the present invention has the following positive and beneficial effects:

[0024] (1) The present invention adds polymethyl methacrylate to the laser ink-absorbing layer coating liquid. Since polymethyl methacrylate has excellent light transmittance and a light transmittance of up to 92%, the light transmittance of the laser ink-absorbing layer coating liquid added with polymethyl methacrylate is also relatively high after drying and forming a film. The laser ink-absorbing layer coating liquid added with polymethyl methacrylate can be coated not only on conventional white polyester PET film base for producing white laser medical films, but also on blue polyester PET film bases and transparent polyester PET with higher requirements on light transmittance for producing blue and transparent laser medical films. Therefore, the present invention can realize the production of different types of laser medical films under the premise of using the same laser ink-absorbing layer coating liquid, shortening the production cycle of simultaneously producing different types of laser medical films, improving the production efficiency of laser medical films, and being suitable for industrial production.

[0025] (2) In the coating process of the present invention, after being coated by the back coating wire rod, it directly enters the back coating drying channel for drying and forming, and then the top coating enters the top coating drying channel after being coated by the slope extrusion coating, thereby realizing one-time online coating of the product and improving the production efficiency of laser medical film.

[0026] (3) The present invention provides an antistatic layer so that the laser medical film has an antistatic function. In addition, the laser medical film of the present invention also has wear resistance, corrosion resistance, scratch resistance and waterproof functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the cross-sectional structure of the laser medical film of the present invention;

[0028] Among them, 1. polyester film base; 2. antistatic layer; 3. laser ink absorbing layer. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Example 1

[0031] A white laser medical film comprises a white polyester base 1. The back side of the white polyester base 1 is provided with an antistatic layer 2, and the front side is provided with a laser ink absorbing layer 3.

[0032] The white polyester base 1 is composed of polyethylene terephthalate PET, with a thickness T of 125 μm, a transmittance P of 24.4%, a haze H of 92.57%, a density D of 0.56, and a smooth appearance, neat edges, and no scratches on the surface.

[0033] The effective component of the antistatic layer 2 is cationic quaternary ammonium salts, and the auxiliary materials are isopropyl alcohol, polyethylene wax emulsion and deionized water.

[0034] The laser ink-absorbing layer 3 contains the following components in percentage by mass: based on the total mass of the aqueous acrylic coating liquid, 1% of polymethyl methacrylate particles with a diameter of 10 μm, 3% of polyvinyl alcohol solution, 28% of aqueous acrylic emulsion, 2% of branched alkyl ester copolymer sodium salt wetting agent, 1.2% of polyethylene wax emulsion lubricant, and the balance is water; the mass fraction of the polyvinyl alcohol solution is 10%, the degree of polymerization is 1700-1900, and the degree of alcoholysis is 88%; the mass fraction of the aqueous acrylic emulsion is 45%.

[0035] A method for preparing a white laser medical film comprises the following steps:

[0036] (1) preparing an antistatic coating liquid: preparing a cationic quaternary ammonium salt surfactant, the mass of which accounts for 20% of the total amount of the antistatic coating liquid, preparing isopropyl alcohol, the mass of which accounts for 5% of the total amount of the antistatic coating liquid, preparing a polyethylene wax emulsion, the mass of which accounts for 5% of the total amount of the antistatic coating liquid, taking deionized water, the mass of which accounts for 70% of the total amount of the antistatic coating liquid, mixing the above-prepared solution with deionized water at room temperature, stirring at 500 r / min for 1 h to make the mixture uniformly mixed, and obtaining a water-soluble antistatic coating liquid for standby use;

[0037] (2) Preparing a dispersion liquid for a laser ink-absorbing layer: Weigh polymethyl methacrylate particles with a diameter of 10 μm and water in a weight ratio of 1:9, put them into a beaker, and stir at 1000 r / min for more than 15 min until no precipitated particle aggregation layer is observed at the bottom of the beaker, thereby obtaining a dispersion liquid for a laser ink-absorbing layer, which is then set aside;

[0038] (3) preparing a laser ink-absorbing layer coating liquid: weighing the polymethyl methacrylate dispersion prepared in step (2), the mass of which accounts for 10% of the total mass of the laser ink-absorbing layer coating liquid; preparing a 10% by mass percentage polyvinyl alcohol solution, the mass of which accounts for 3% of the total mass of the laser ink-absorbing layer coating liquid; preparing a 45% by mass percentage aqueous acrylic emulsion, the mass of which accounts for 28% of the total mass of the laser ink-absorbing layer coating liquid; preparing a branched alkyl ester copolymer sodium salt wetting agent, the mass of which accounts for 2% of the total mass of the laser ink-absorbing layer coating liquid; preparing a polyethylene wax emulsion lubricant, the mass of which accounts for 1.2% of the total mass of the laser ink-absorbing layer coating liquid; mixing the above-prepared solutions with water, stirring them thoroughly for 1 hour, and mixing them evenly to obtain a laser ink-absorbing layer coating liquid for later use;

[0039] (4) Coating: First, corona treat the back and front sides of the polyester base 1 in turn, and the conductivity of the corona treatment is 320S / m. Secondly, the prepared antistatic layer coating liquid is directly filtered through a 200-mesh filter cloth. The laser ink-absorbing layer coating liquid is first filtered through a 20 μm filter bag and then placed in a static pot for standby use. During coating, it is filtered through a 10 μm filter element of the coating system. Finally, back coating is performed using a wire rod and then directly enters the back coating drying channel for drying. Then, top coating is performed by slide extrusion coating and then enters the top coating drying channel for forming. The thickness of the double-sided coating after drying is 15-20 μm in total;

[0040] (5) placing the coated polyester film base 1 in step (4) into a tunnel drying device for drying to obtain a laser medical film; after drying, the thickness of the laser ink-absorbing layer coating 3 on the front side of the polyester film base 1 is 10-15 μm, and the thickness of the antistatic layer coating 2 on the back side of the polyester film base 1 is 3-5 μm; the drying temperature is 75-80° C., and the drying time is 30-60 min.

[0041] In step (4), the corona treatment is to apply high-frequency and high-voltage electricity between two electrodes under normal pressure. When the voltage exceeds the ionization resistance of the air gap, continuous discharge can be generated, thereby generating a plasma formed by corona discharge in the gap between the discharge knife holder and the blade. When treating the surface of the substrate, firstly, the high-frequency and high-voltage electricity ionizes the air between the electrodes to generate a large amount of plasma gas and ozone, which directly or indirectly interact with the surface molecules of the plastic to generate polar groups such as carbonyl and nitrogen-containing groups on the surface molecular chains, and the surface tension is significantly increased; secondly, after the electric spark impacts the substrate, the surface of the substrate is roughened, thereby improving the wettability and contact area of ​​the adhesive and the coating liquid.

[0042] The environmental conditions for coating in step (4) are: temperature of 19-25° C. and humidity of 35-55%.

[0043] The finished product test results of the white laser medical film obtained in this embodiment are as follows: thickness T = 135 μm, transmittance P = 24.2%, haze H = 92.68%, density D = 0.55.

[0044] Since the white medical laser film produced by the white film base forms a contrast with the base color through its own laser ink absorption image after printing, it does not need to be observed on the film viewing light. Therefore, there is no requirement for the transmittance and haze performance of the white medical laser film, that is to say, there is no need to make an in-depth comparison of the performance difference between the original white film base and the finished product.

[0045] Example 2

[0046] A blue laser medical film comprises a blue polyester base 1. The reverse side of the white polyester base 1 is provided with an antistatic layer 2, and the front side is provided with a laser ink absorbing layer 3.

[0047] The blue polyester base 1 is composed of polyethylene terephthalate PET, with a thickness T of 175 μm, a transmittance P of 74.4%, a haze H of 1.97%, and a density D of 0.15. It has a smooth appearance, neat edges, and no scratches on the surface.

[0048] The components of the antistatic layer and the laser ink-absorbing layer, and the preparation method of the blue laser medical film are the same as those in the embodiment.

[0049] The finished product test results of the blue laser medical film obtained in this embodiment are as follows: thickness T=185 μm, transmittance P=75.0%, haze H=37.62%, density D=0.14.

[0050] Since the blue laser medical film needs to be placed on a film viewing lamp for observation after printing the image when in use, the light transmittance of the finished product has a high requirement, that is, for the blue polyester film base, before and after coating the antistatic layer and the laser ink absorbing layer, the light transmittance index of the blue film base and the finished blue medical film should reach a certain value and should not be reduced too much. Therefore, by replacing the blue polyester PET film base produced by different manufacturers, the index test results of the original film base and the corresponding blue medical film products produced by each manufacturer measured according to the steps in Example 2 are shown in Table 1 below.

[0051] Table 1 Index test results of different blue polyester film bases and their corresponding blue medical films

[0052] type Thickness Tμm Light transmittance P% Haze H% Density D Blue polyester film base 1 175 70.4 12.31 0.18 Blue medical film 1 184 71.5 38.80 0.16 Blue polyester film base 2 174 74.9 2.57 0.14 Blue medical film 2 182 75.2 31.69 0.14 Blue polyester film base 3 175 74.7 2.47 0.15 Blue medical film 3 183-184 74.6 31.70 0.15

[0053] As can be seen from Table 1, when the laser ink-absorbing layer coating liquid of the present invention is coated on different blue polyester PET film bases, the coating after coating and drying has little effect on the transmittance and density of the finished blue medical film, which is almost negligible, and even has a slightly enhanced effect on the transmittance of the blue medical film product. This is mainly due to the addition of polymethyl methacrylate (PMMA) in the laser ink-absorbing layer coating liquid. The polymethyl methacrylate (PMMA) particles themselves are colorless and transparent, and the transmittance is as high as 90%-92%. Therefore, as a component raw material in the laser ink-absorbing layer coating liquid of the blue medical film, directly coating the laser ink-absorbing layer coating liquid on the blue polyester PET does not affect the final transmittance of the laser ink-absorbing layer after drying. In addition, the addition ratio of polymethyl methacrylate particles in the present invention is relatively small, so it has little effect on the performance of the laser ink-absorbing layer coating liquid after film coating.

[0054] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a laser medical film, characterized in that: The following steps are involved: (1) preparing an antistatic coating liquid: preparing a cationic quaternary ammonium salt surfactant, the mass of which accounts for 20% of the total amount of the antistatic coating liquid, preparing isopropyl alcohol, the mass of which accounts for 5% of the total amount of the antistatic coating liquid, preparing a polyethylene wax emulsion, the mass of which accounts for 5% of the total amount of the antistatic coating liquid, taking deionized water, the mass of which accounts for 70% of the total amount of the antistatic coating liquid, mixing the above-prepared solution with deionized water at room temperature, stirring at 300-500 r / min for 1-1.5h to make them evenly mixed, to obtain a water-soluble antistatic coating liquid for standby use; (2) Preparation of laser ink absorption layer dispersion: Weigh polymethyl methacrylate particles with a diameter of 10 μm and water in a weight ratio of 1:9, put them into a beaker, and stir at 1000-1500 r / min for 15-30 min until no precipitated particle aggregation layer is seen at the bottom of the beaker. The polymethyl methacrylate dispersion of the laser ink absorption layer is obtained and set aside. (3) Preparing a laser ink-absorbing layer coating liquid: Weigh the polymethyl methacrylate dispersion prepared in step (2), the mass of which accounts for 10% of the total mass of the laser ink-absorbing layer coating liquid; prepare a 10% by mass percentage polyvinyl alcohol solution, the mass of which accounts for 3% of the total mass of the laser ink-absorbing layer coating liquid; prepare a 45% by mass percentage aqueous acrylic emulsion, the mass of which accounts for 28% of the total mass of the laser ink-absorbing layer coating liquid; prepare a branched alkyl ester copolymer sodium salt wetting agent, the mass of which accounts for 2% of the total mass of the laser ink-absorbing layer coating liquid; prepare a polyethylene wax emulsion lubricant, the mass of which accounts for 1.2% of the total mass of the laser ink-absorbing layer coating liquid; mix the above-prepared solutions with water, stir thoroughly for 1-1.5 hours, mix evenly, and obtain a laser ink-absorbing layer coating liquid for standby use; The mass fraction of the polyvinyl alcohol solution is 10%, the degree of polymerization is 1700-1900, and the degree of alcoholysis is 88%; (4) Coating: First, the polyester film base is subjected to corona treatment. Then, the prepared antistatic layer coating liquid and laser ink absorption layer coating liquid are subjected to static defoaming and filtration treatments in turn. Finally, the laser ink absorption layer coating liquid and the antistatic layer coating liquid are coated on the front and back sides of the corona treated polyester film base respectively by using a slope extrusion coating method. The material of the polyester base is polyethylene terephthalate; (5) placing the polyester film base coated in step (4) into a tunnel drying device for drying to obtain a laser medical film; In the step (5), the thickness of the laser ink-absorbing layer coating on the front side of the polyester film base after drying is 10-15 μm; the thickness of the antistatic layer coating on the back side of the polyester film base after drying is 3-5 μm.

2. The method for preparing laser medical film according to claim 1, characterized in that: The polyester base has a thickness T of 100-200 μm, a light transmittance P of 20-75%, a haze H of 1-93%, and a density D of 0.1-0.

6.

3. The method for preparing laser medical film according to claim 1, characterized in that: In the step (4), the corona treatment is performed by applying high-frequency high-voltage electricity between two electrodes under normal pressure, first corona treating the back side of the polyester base and then corona treating the front side of the polyester base, and the corona conductivity is 320 S / m.

4. The method for preparing laser medical film according to claim 1, characterized in that: In the step (4), the antistatic layer coating liquid is directly filtered through a 200-mesh filter cloth; the laser ink-absorbing layer coating liquid is first filtered through a 20 μm filter bag and then placed in a static pot for standby use, and is then filtered through a 10 μm filter element of the coating system during coating.

5. The method for preparing laser medical film according to claim 1, characterized in that: The coating environment conditions in step (4) are: temperature of 19-25° C. and humidity of 35-55%.

6. The method for preparing laser medical film according to claim 1, characterized in that: The drying temperature in step (5) is 75-80°C and the drying time is 30-60 minutes.

7. A laser medical film prepared by the preparation method according to any one of claims 1 to 6.

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