Polyurethane multilayer film and method for producing the same

Abstract

The present invention discloses a polyurethane multilayer film and its manufacturing method. The manufacturing method includes the steps of: applying a flexible polyurethane coating liquid to the surface of a polyethylene terephthalate release film and drying it to form a flexible polyurethane film coating, and then performing plasma discharge treatment; applying a pressure-sensitive adhesive liquid to the surface of the flexible polyurethane film coating in step (1) to form a pressure-sensitive adhesive layer; applying a flexible polyurethane coating liquid to the surface of another polyethylene terephthalate release film and drying it to form a flexible polyurethane film coating, performing plasma discharge treatment, and then combining with the pressure-sensitive adhesive layer in step (2); peeling two polyethylene terephthalate release films, applying a coating containing a heat-shielding nano material to the surface of the flexible polyurethane film coating on one side, and baking and curing it; applying a pressure-sensitive adhesive liquid to the surface of the other flexible polyurethane film coating. In the present invention, the core structure is changed to the conventional TPU base film, so that the problem of poor smoothness of the TPU base film manufactured by the casting method can be solved.

Description

Technical Field

[0001] The present invention relates to the field of film manufacturing, and particularly to a polyurethane multilayer film and a method for manufacturing the same.

Background Art

[0002] Conventionally, there are a very large number of types of commercially available automotive paint protection films. Most of their structures are to attach a general PVC (polyvinyl chloride) adhesive film to the automotive paint to protect it from external frictional damage. Since the plasticizer contained in the PVC base film gradually moves to the surface over time, the PVC protection film gradually hardens and becomes brittle in the latter half of the usage period. When the plasticizer transfers to the adhesive layer, phenomena such as the protection film being damaged, bubbles being generated, or peeling occur, making it very unsightly. Therefore, currently, a thermoplastic polyurethane elastomer base film is gradually beginning to be used as an automotive paint protection film.

[0003] Furthermore, since the polyurethane elastomer base film has the effect of cushioning impacts, in addition to being used as an automotive paint protection film, it has come to exhibit heat insulation function, impact resistance, and scratch resistance simultaneously in place of the current PET automotive glass heat insulation film.

[0004] However, as an issue when applying a heat insulation film to the front glass of an automobile, general TPU (thermoplastic polyurethane elastomer rubber) base films are all manufactured by the casting method under high-temperature conditions (120 - 200°C), where TPU particles are melted and cast, and then cooled. Since the viscosity of the TPU melt is usually high, the smoothness of the TPU base film obtained from TPU particles by the casting method is poor, and ultimately the surface roughness of the TPU film becomes high. When used on the front glass of an automobile, since the front glass is inclined and forms an acute angle with the line of sight of a person, light is scattered due to the surface roughness of the TPU film, affecting the visibility. Therefore, a self-healing type heat insulation film with better smoothness is required.

Summary of the Invention

[0005] The present invention relates to a polyurethane multilayer film and a method for manufacturing the same.

[0006] In the present invention, an application method is adopted, and by using a core structure of a flexible PU coating / pressure-sensitive adhesive / flexible PU coating, the problem of poor smoothness of a TPU base film manufactured by a casting method can be solved instead of the conventional TPU base film.

[0007] According to the research results of the inventors, when a flexible polyurethane coating is directly formed by a method using a flexible polyurethane coating solution and then plasma discharge treatment is performed on the thin film layer, since the flexible polyurethane coating contains carboxylic acid silane-modified nano-silicon dioxide and 8-mercapto-1-octanethiol, not only can the adhesion strength of each layer of the thin film be improved, but also the adverse effect of light scattering of the thin film particles can be effectively avoided, and the smooth performance of the thin film can be made more excellent.

[0008] The present invention provides a method for manufacturing a polyurethane multilayer film, comprising the following steps: (1) A step of applying a flexible polyurethane coating solution onto the surface of a polyethylene terephthalate release film, drying it to form a flexible polyurethane film coating, and then performing plasma discharge treatment. (2) A step of applying a pressure-sensitive adhesive solution onto the surface of the flexible polyurethane film coating in step (1) to form a pressure-sensitive adhesive layer. (3) A step of applying a flexible polyurethane coating solution onto the surface of another polyethylene terephthalate release film, drying it to form a flexible polyurethane film coating, performing plasma discharge treatment, and then laminating it with the pressure-sensitive adhesive layer in step (2). (4) A step of peeling off two polyethylene terephthalate release films, applying a coating containing a heat-insulating nano material onto the surface of the flexible polyurethane film coating on one side, baking and curing it, and applying a pressure-sensitive adhesive solution onto the surface of the flexible polyurethane film coating on the other side. In steps (1) and (3), the raw material formulation of the flexible polyurethane coating solution is as follows: aqueous polyurethane resin, carboxylic acid silane-modified nano-silicon dioxide, metal oxide nanoparticles, 8-mercapto-1-octanethiol, wetting agent, defoaming agent, deionized water.

[0009] Among them, the pressure-sensitive adhesive liquid is preferably an acrylic pressure-sensitive adhesive.

[0010] In the present invention, 8-mercapto-1-octanethiol can effectively improve the dispersibility of particles. The mercapto group at the molecular end can modify nano-silicon dioxide and metal oxide nanoparticles, facilitating the dispersion of particles. The other hydroxyl group at the molecular end participates in the curing reaction of the aqueous polyurethane resin to form a spatial network structure. On the one hand, the particles are more uniformly dispersed in the polyurethane coating solution, and on the other hand, the adhesion performance and mechanical properties of the flexible polyurethane coating can also be improved.

[0011] Among them, the metal oxide nanoparticles are preferably any one or more of titanium dioxide nanoparticles, alumina nanoparticles, and zinc oxide nanoparticles.

[0012] Among them, the wetting agent is preferably the dispersant SN-5040.

[0013] Among them, the defoaming agent is preferably the defoaming agent CF-16. Among them, the aqueous polyurethane resin is preferably the polyurethane dispersion SYNTEGRA (registered trademark) purchased from Dow or the polyurethane dispersion Bayhydrol (registered trademark) purchased from Bayer.

[0014] Among them, the gas used for plasma discharge treatment is preferably nitrogen.

[0015] Among them, the carboxylic acid silane is preferably 4(4-carboxyanisyl)silane.

[0016] Among them, the carboxylic acid silane-modified nano-silicon dioxide is preferably produced by mixing silicon dioxide sol and carboxylic acid silane in a solvent DMF and heating and reacting them in a vacuum-sealed state. The temperature of the heating reaction is preferably 90 to 100 °C, and the time of the heating reaction is preferably 20 to 30 hours. The temperature of the firing and curing in step (4) is preferably 70 to 120 °C, and the time is preferably 1 to 8 minutes.

[0017] The present invention also provides a polyurethane multilayer film produced by the above-described production method.

[0018] The polyurethane multilayer film of the present invention is laminated and combined with a pressure-sensitive adhesive layer, a flexible polyurethane coating, a pressure-sensitive adhesive layer, a flexible polyurethane coating, and a heat-insulating nano material layer in order from the bottom. The thickness of the pressure-sensitive adhesive layer is preferably 10 to 20 microns. The thickness of the flexible polyurethane coating is preferably 20 to 50 microns. The thickness of the heat-insulating nano material layer is preferably 5 to 15 microns. Within the scope of common knowledge in the art, by arbitrarily combining the above-mentioned respective optimum conditions, each optimum embodiment of the present invention can be obtained. All the reagents and raw materials used in the present invention are commercially available.

[0019] The positive progressive effect obtained by the present invention: By using the core material structure of flexible PU coating / pressure-sensitive adhesive / flexible PU coating, the problem of poor smoothness of the TPU base film produced by the casting method can be solved instead of the conventional TPU base film.

Embodiments for Carrying Out the Invention

[0020] Specific Examples The present invention will be further described below through examples, but the present invention is not limited to the scope of the described examples. In the following examples, the experimental methods for which specific conditions are not explicitly stated shall follow the normal methods and conditions or select the product manuals.

[0021] Solvent resistance test method: Spray 1 milliliter of 2-methylbenzene onto the surface of the test material, and after 30 seconds, wipe it off with blotting paper. If no obvious change (such as melting deformation, peeling of the coating, etc.) is observed in the appearance of the material, it is considered that the solvent resistance test is qualified.

[0022] Self-repair test method: Make brush marks on the surface of the thin film with a linear wire brush, and then observe whether the brush marks disappear naturally within 1 hour or disappear under a heat source (such as pouring hot water). If it can disappear, it is considered that the material has a self-repair function.

[0023] Gloss evaluation method: Attach the flexible polymer substrate with a self-repair coating to a black metal plate, and observe the superiority or inferiority of the gloss of the material surface from the front and side (45 degrees). If the surface is smooth and has reflected light, and the reflection is clear and sharp, it is considered that the gloss is excellent; otherwise, it is considered that the gloss is inferior.

[0024] Stain resistance evaluation method: Mark the surface of the coating with an oil-based black marker (Dexy 6881). After the mark dries, leave it for 1 day, and then observe the removal situation of the mark by directly wiping it with a glasses wipe or wiping it with a glasses wipe containing anhydrous alcohol. If the mark can be completely wiped off without leaving any traces, it is considered that the stain resistance is excellent; if the mark cannot be wiped off, it is considered that the stain resistance is inferior; if the mark can be wiped off but there are slight traces, it is considered that the stain resistance is good.

[0025] Elongation at break test method: Cut the test material into a strip with a width of 5 centimeters and a length of 2 centimeters, mark the central 2-centimeter length, apply force to stretch it on both sides, mark the length of the marked part as L1 when cracks occur, and then calculate the elongation at break according to the following formula. Elongation at break (%) = (L1 - 2) / 2

[0026] The weather resistance test method is as follows: Use an Eye Super UV Tester W-151 (Iwaki Electric Co., Ltd.) to conduct a weather resistance performance test. One cycle is to hold for 5 hours under a temperature of 63°C, relative humidity of 50%, illuminance of 50 watts / square centimeter, and watering for 10 seconds / hour, and then hold for 1 hour under a temperature of 30°C and relative humidity of 95%. After repeating the above weather resistance cycle 300 times, observe the coating using the naked eye and a microscope (×250). If no cracks or local peeling are seen, it indicates that the surface of the coating is good and the weather resistance performance is excellent. Each composition is shown in parts by weight.

[0027] The pressure-sensitive adhesive layer is a pressure-sensitive adhesive formulation commonly used in the art. Specifically, it contains acrylic acid, methyl acrylate, myristic acid, [Chemical formula] , butadiene, and toluene.

[0028] For the coating of the heat-insulating nano material, adopt the heat-insulating coating commonly used in the art; each numerical value in the following examples is in parts by weight.

[0029] Example 1 The manufacturing process of the polyurethane multilayer film is as follows:

[0030] (1) Apply a flexible polyurethane coating solution to the surface of a polyethylene terephthalate release film and dry it to form a flexible polyurethane film coating, and then perform plasma discharge treatment; the gas used for the plasma discharge treatment is nitrogen, and the time is 10 minutes.

[0031] (2) Apply an acrylic pressure-sensitive adhesive solution to the surface of the flexible polyurethane film coating in step (1) to form a pressure-sensitive adhesive layer.

[0032] (3) Apply a flexible polyurethane coating solution to the surface of another polyethylene terephthalate release film, dry it to form a flexible polyurethane film coating, and perform plasma discharge treatment (the gas used for plasma discharge treatment is nitrogen, and the time is 10 minutes). Then, laminate it with the pressure-sensitive adhesive layer in step (2).

[0033] (4) Peel off two polyethylene terephthalate release films, apply a coating containing a heat-insulating nano material to the surface of the flexible polyurethane film coating on one side, and bake and cure it (bake at 70 °C for 8 minutes); apply an acrylic pressure-sensitive adhesive solution to the surface of the flexible polyurethane film coating on the other side.

[0034] In this example, the raw material formulation of the flexible polyurethane coating solution contains the following weight parts: 20 parts of aqueous polyurethane resin, 10 parts of carboxylic acid silane-modified nano silicon dioxide, 5 parts of metal oxide nano particles, 3 parts of 8-mercapto-1-octanethiol, 1 part of wetting agent, 1 part of defoaming agent, and 20 parts of deionized water.

[0035] In this example, the metal oxide nano particles are titanium dioxide nano particles, the wetting agent is dispersant SN-5040, the defoaming agent is defoaming agent CF-16, and the aqueous polyurethane resin is polyurethane dispersion SYNTEGRA (registered trademark) purchased from Dow.

[0036] The carboxylic acid silane-modified nano silicon dioxide is produced by mixing silicon dioxide sol and 4-(4-carboxyanisyl) silane in solvent DMF and heating and reacting them under a vacuum-sealed state. The temperature of the heating reaction is 90 °C, and the time of the heating reaction is 30 hours.

[0037] The polyurethane multilayer film produced in this example is laminated and compounded in order from bottom to top with a pressure-sensitive adhesive layer, a flexible polyurethane coating, a pressure-sensitive adhesive layer, a flexible polyurethane coating, and a heat-insulating nano material layer. The thickness of the pressure-sensitive adhesive layer is 10 microns. The thickness of the flexible polyurethane coating is 20 microns. The thickness of the heat-insulating nano material layer is 5 microns.

[0038] The test results are as follows: (1) The adhesion strength of the polyurethane coating is excellent, it does not peel off easily, and it reaches ASTM 5B in the cross-cut test.

[0039] (2) The elongation at break reaches 400%, and the breaking strength reaches 45 MPa.

[0040] (3) It has excellent abrasion resistance and will not be scratched even after reciprocating friction more than a thousand times with a load of 1 kg of 0000# steel wire.

[0041] (4) It has excellent weather resistance. After repeating the weather cycle 300 times, no cracks or local peeling were still found on the surface of the coating.

[0042] (5) The thin film is smooth, has excellent smoothness performance, and the gloss at 20 degrees is 98.

[0043] Example 2 The manufacturing process of the polyurethane multilayer film is as follows:

[0044] (1) Apply a flexible polyurethane coating solution on the surface of a polyethylene terephthalate release film and dry it to form a flexible polyurethane film coating, and then perform plasma discharge treatment. The gas used for the plasma discharge treatment is nitrogen, and the time is 15 minutes.

[0045] (2) Apply an acrylic pressure-sensitive adhesive solution on the surface of the flexible polyurethane film coating in step (1) to form a pressure-sensitive adhesive layer.

[0046] (3) Apply a flexible polyurethane coating solution on the surface of another polyethylene terephthalate release film and dry it to form a flexible polyurethane film coating, and perform plasma discharge treatment (the gas used for the plasma discharge treatment is nitrogen, and the time is 15 minutes), and then laminate it with the pressure-sensitive adhesive layer in step (2).

[0047] (4) Peel off two polyethylene terephthalate release films, apply a coating containing a heat-insulating nano material on the surface of the polyurethane film coating on one side, and bake and cure it (bake at 100 °C for 5 minutes). Apply an acrylic pressure-sensitive adhesive solution on the surface of the polyurethane film coating on the other side.

[0048] In this example, the raw material formulation of the flexible polyurethane coating solution contains the following parts by weight: 25 parts of aqueous polyurethane resin, 13 parts of carboxylic acid silane-modified nano silicon dioxide, 7 parts of metal oxide nanoparticles, 3 parts of 8-mercapto-1-octanethiol, 1 part of wetting agent, 1 part of defoaming agent, and 30 parts of deionized water.

[0049] In this example, the metal oxide nanoparticles are alumina nanoparticles, the wetting agent is dispersant SN-5040, the defoaming agent is defoaming agent CF-16, and the aqueous polyurethane resin is polyurethane dispersion Bayhydrol® purchased from Bayer.

[0050] The carboxylic acid silane-modified nano silicon dioxide is produced by mixing silicon dioxide sol and 4-(4-carboxyanisyl)silane in solvent DMF and heating and reacting them under vacuum sealing. The temperature of the heating reaction is 100 °C and the time of the heating reaction is 25 hours.

[0051] The polyurethane multilayer film produced in this example is laminated and compounded in order from bottom to top with a pressure-sensitive adhesive layer, a flexible polyurethane coating, a pressure-sensitive adhesive layer, a flexible polyurethane coating, and a heat-insulating nano material layer. The thickness of the pressure-sensitive adhesive layer is 20 microns. The thickness of the flexible polyurethane coating is 50 microns. The thickness of the heat-insulating nano material layer is 15 microns.

[0052] The test results are as follows: (1) The adhesion strengths of the polyurethane coatings are all excellent, they are not easily peeled off, and reach ASTM 5B in the cross-cut test.

[0053] (2) The elongation at break reaches 400%, and the breaking strength reaches 46 MPa.

[0054] (3) It has excellent abrasion resistance. Even when the load of the #0000 steel wire is 1 kg and it reciprocates and rubs more than a thousand times, it will not be scratched.

[0055] (4) It has excellent weather resistance. After repeating the weather cycle 300 times, no cracks or local peeling were still observed on the surface of the coating.

[0056] (5) The thin film is smooth, has excellent smoothness performance, and the gloss at 20 degrees is 99.

[0057] Comparative Example 1 In this comparative example, the raw material formulation of the flexible polyurethane coating solution does not contain carboxylic acid silane-modified nano-silicon dioxide, and other parameter conditions are the same as those in Example 1. A polyurethane multilayer film is manufactured. When its performance is tested, the surface of the thin film is not smooth to the naked eye, and the gloss at 20 degrees is 81.

[0058] Comparative Example 2 In this comparative example, 8-mercapto-1-octanethiol in the raw material formulation of the flexible polyurethane coating solution is replaced by n-octanethiol, and other parameter conditions are the same as those in Example 1. A polyurethane multilayer film is manufactured. When its performance is tested, the surface of the thin film is not smooth to the naked eye, and the gloss at 20 degrees and the orange peel value are 85.

Claims

1. (1) A step of applying a flexible polyurethane coating solution onto the surface of a polyethylene terephthalate release film, drying it to form a flexible polyurethane film coating, and then performing a plasma discharge treatment; (2) A step of applying a pressure-sensitive adhesive solution onto the surface of the flexible polyurethane film coating in step (1) to form a pressure-sensitive adhesive layer; (3) A step of applying a flexible polyurethane coating solution onto the surface of another polyethylene terephthalate release film, drying it to form a flexible polyurethane film coating, performing a plasma discharge treatment, and then laminating it with the pressure-sensitive adhesive layer in step (2); (4) Peeling off two sheets of polyethylene terephthalate release film, applying a coating containing a heat-insulating nanomaterial onto the surface of the flexible polyurethane film coating on one side, and baking and curing the flexible polyurethane film coating; A step of applying a pressure-sensitive adhesive solution onto the surface of the flexible polyurethane film coating on the other side, and In steps (1) and (3), The raw material formulation of the flexible polyurethane coating solution is as follows: aqueous polyurethane resin, carboxylic acid silane-modified nano-silicon dioxide, metal oxide nanoparticles, 8-mercapto-1-octanethiol, wetting agent, defoaming agent, deionized water A method for manufacturing a polyurethane multilayer film, characterized in that.

2. The method for manufacturing a polyurethane multilayer film according to claim 1, characterized in that the pressure-sensitive adhesive solution is an acrylic pressure-sensitive adhesive.

3. The method for manufacturing a polyurethane multilayer film according to claim 1, characterized in that the metal oxide nanoparticles are any one or more of titanium dioxide nanoparticles, alumina nanoparticles, and zinc oxide nanoparticles.

4. The gas used in the plasma discharge treatment is nitrogen A method for manufacturing a polyurethane multilayer film according to claim 1, characterized in that.

5. The carboxylic acid silane is tetrakis(4-carboxyphenyl)silane, characterized in that The method for manufacturing a polyurethane multilayer film according to claim 1.

6. The carboxylic acid silane-modified nano-silicon dioxide is manufactured by the following method: Mixing silicon dioxide sol and carboxylic acid silane in a solvent DMF, and heating and reacting in a vacuum-sealed state; The temperature of the heating reaction is 90 to 100 °C; The time of the heating reaction is 20 to 30 hours; A method for manufacturing a polyurethane multilayer film according to claim 1, characterized in that.

7. The method for producing a polyurethane multilayer film according to any one of claims 1 to 6, characterized in that the temperature of the baking and curing of the project (4) is 70 to 120 ° C and the time is 1 to 8 minutes.

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