Thermal insulation polyurethane composite thin film and preparation method therefor

Abstract

Disclosed in the present invention are a thermal insulation polyurethane composite thin film and a preparation method therefor. The preparation method comprises the following steps: under an inert atmosphere, uniformly mixing citric acid and polyethylene glycol 600, heating and stirring, adding an acidic catalyst, and stirring to react until the weight of the system no longer changes, obtaining a polyester polyol; in DMF, under the action of a catalyst, uniformly mixing the polyester polyol and a polylactic acid polyol then adding a polyisocyanate, and heating with stirring to react, obtaining a prepolymer; adding a chain extender, and stirring to react, obtaining a polyurethane elastomer solution; coating the polyurethane elastomer solution on a PET release film, and drying, obtaining a TPU base film; coating a pressure-sensitive adhesive layer on the back of the base film, baking and drying, peeling off the release film, and then applying a coating containing a thermal insulation nanomaterial to the surface of the base film and curing. The composite then film obtained by the present invention has high transparency, and achieves good self-healing functionality through the use of the polyurethane elastomer.

Description

Thermal insulation polyurethane composite film and preparation method thereof TECHNICAL FIELD

[0001] The present application relates to the field of film preparation, in particular to a thermal insulation polyurethane composite film and a preparation method thereof. BACKGROUND

[0002] At present, the TPU car protection film sold on the market is mainly used for the surface of car paint. It has excellent mechanical properties and durability, and can further improve the appearance of car paint and even the car while protecting the car paint from the damage of the external environment.

[0003] At present, the commonly used film body of the car glass film sold on the market is optical grade hard PET (polyethylene terephthalate), which has excellent optical performance and low haze and does not affect the line of sight. In use, unlike the TPU car paint protection film, the PET film is attached to the inner side of the glass (i.e. the side facing the car interior). One disadvantage of the inner attachment is that the VOC (volatile organic compounds) formed in the production process of the PET window film product formula, such as the residual solvent and monomers in the pressure-sensitive adhesive, can easily stay in the car interior for a long time, causing pollution in the car interior. If it can be changed to outer attachment, this problem can be avoided. However, the PET film itself has poor resistance to ultraviolet aging and hydrolysis, so even if it is attached outside, it cannot be used for a long time. At the same time, the PET film does not have the ability to resist external mechanical damage (such as scratching), which further limits the possibility of PET outer attachment. The TPU (polyurethane elastomer) film has heat repairability and excellent weather resistance, which can avoid the problem of poor durability caused by the use of PET film. However, the biggest problem of the TPU (polyurethane elastomer) protection film when attached to the car glass is poor transparency, mainly reflected in high transmission haze, which will affect the line of sight of the person inside the car. Especially when it is used on the surface of the front glass, since the front glass has a certain angle with the driver's line of sight, the defect of high transmission haze will be magnified in the case of poor night vision, which seriously affects the actual application of the product. Therefore, a film with low transmission haze, excellent repair performance and good outdoor durability is needed to replace the existing PET film and TPU film, so as to realize the application of car glass film outer attachment. SUMMARY

[0004] The present application relates to a thermal insulation polyurethane composite film and a preparation method thereof.

[0005] The composite film prepared by the solution method has high transparency, and the polyurethane elastomer realizes good self-repairing function, and the addition of the thermal insulation material layer makes the film have good thermal insulation effect.

[0006] The inventors find through research that the TPU film prepared by the solution method can replace PET as the window film substrate and achieve the optical performance of PET, while having the repairing and impact functions.

[0007] A preparation method of a thermal insulation polyurethane composite film, comprising the following steps:

[0008] (1) under an inert atmosphere, citric acid and polyethylene glycol 600 are uniformly mixed, heated and stirred, an acidic catalyst is added, and stirring is performed until the system weight is unchanged, to obtain a polyester polyol;

[0009] (2) the polyester polyol and polylactic acid polyol are uniformly mixed in a solvent under the action of a catalyst, and then a polyisocyanate is added, heated and stirred to obtain a prepolymer;

[0010] (3) a chain extender is added, and stirring is performed to obtain a polyurethane elastomer solution;

[0011] (4) the polyurethane elastomer solution is coated on a PET release film, and after drying, a TPU base film is obtained;

[0012] (5) a pressure-sensitive adhesive layer is coated on the back of the base film, and after baking and drying, the release film is peeled off;

[0013] (6) a coating layer containing thermal insulation nanomaterials is coated on the surface of the base film, and curing is performed.

[0014] In step (1), the acidic catalyst is preferably one or more of p-toluenesulfonic acid, concentrated sulfuric acid, and concentrated hydrochloric acid; and the solvent is preferably one or more of DMF, DMSO, THF, and methyl isobutyl ketone.

[0015] In step (1), the inert atmosphere is preferably a nitrogen atmosphere.

[0016] In step (2), the catalyst is preferably dibutyltin dilaurate, an organic bismuth catalyst, an organic zinc catalyst, or a tertiary amine catalyst.

[0017] In step (2), the prepolymer has a weight average molecular weight of preferably 1000-20000.

[0018] In step (4), the polyurethane elastomer solution is preferably coated on the PET release film by roll coating, spraying, or dipping.

[0019] The coating of the heat insulation nanomaterials is preferably a heat insulation coating in the art, and the formula of the heat insulation coating preferably comprises the following components by weight: 20-25 parts of heat insulation material slurry, 72-83 parts of film forming material, and 0.5-0.6 parts of antioxidant. The heat insulation material slurry is preferably a dispersion liquid of lanthanum hexaboride, indium tin oxide, antimony tin oxide or cesium tungstate powder. When ultraviolet light curing is used, the film forming material comprises 50-55 parts of diluent, 20-25 parts of oligomer and 2-3 parts of initiator. The diluent is preferably 1,6-hexanediol diacrylate (HDDA), trimethylolpropane triacrylate (TMPTA) or tripropylene glycol diacrylate (TPGDA). The oligomer is preferably polyurethane acrylate. The initiator is preferably an Irgacure series initiator product of IGM Company. When baking heat curing is used, the film forming material is polyacrylate or polyurethane. The antioxidant is preferably a Tinuvin series antioxidant product of BASF Company.

[0020] The polyisocyanate is preferably selected from diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), pentamethylene diisocyanate (PDI), hexamethylene diisocyanate (HDI), methylene bis(4-cyclohexyl isocyanate) (HMDI) and mixtures thereof.

[0021] In step (3), the weight average molecular weight of the polyurethane elastomer is preferably 10,000-200,000.

[0022] The polylactic acid polyol is preferably HPB500 or HPB1000 purchased from Anhui Huaihai Biological Technology Co., Ltd.

[0023] The chain extender is preferably one or more selected from ethane-1,2-diol, propane-1,3-diol, butane-1,4-diol and hexane-1,6-diol, diethylene glycol and triethylene glycol.

[0024] In step (5), the curing is preferably baking curing or UV curing, and more preferably baking curing.

[0025] The application further provides a heat insulation polyurethane composite film prepared by the above preparation method.

[0026] The heat insulation polyurethane composite film comprises a pressure sensitive adhesive layer, a base film and a heat insulation nanomaterial layer which are laminated and combined in sequence from bottom to top.

[0027] Preferably, the thickness of the pressure sensitive adhesive layer is 5-50 microns, and more preferably 8-30 microns.

[0028] Preferably, the thickness of the base film is 20-350 microns, and more preferably 50-200 microns.

[0029] Preferably, the thickness of the thermal insulation nanomaterial layer is 1-30 microns, preferably 5-20 microns.

[0030] On the basis of common knowledge in the art, the above-mentioned preferred conditions can be combined arbitrarily, thereby obtaining preferred examples of the present application.

[0031] The reagents and raw materials used in the present application are commercially available.

[0032] The positive progress achieved by the present application is that the composite film obtained by the present application has very high transparency, and the use of polyurethane elastomer realizes very good self-repairing function. DETAILED DESCRIPTION

[0033] The present application will be further described by way of examples below, but the present application is not limited to the scope of the examples. The experimental methods not specified in the following examples are selected according to conventional methods and conditions, or according to the instructions of the goods.

[0034] Solvent resistance test method: 1 ml of xylene is sprayed onto the surface of the material to be tested, and after 30 seconds, the material is wiped dry with a wiping paper. If there is no obvious change in the appearance of the material (such as swelling, deformation, coating peeling, etc.), it is considered that the solvent resistance test is qualified.

[0035] Self-repairing test method: after a straight copper wire brush is used to brush a scratch on the surface of the film, it is observed whether the scratch can disappear automatically within 1 hour or under the condition of a heat source (such as hot water pouring). If it can disappear, it is considered that the material has self-repairing function.

[0036] Gloss evaluation method: the flexible polymer substrate coated with the self-repairing coating is adhered to a black metal plate, and the gloss of the material surface is observed from the front and side (45 degrees) respectively. If the surface is smooth and reflective, and the reflection is clear and sharp, it is considered that the gloss is excellent, otherwise it is considered that the gloss is poor.

[0037] Stain resistance evaluation method: marks are made on the surface of the coating with a Dali 6881 black oil-based marker, and after 10 minutes, the marks are wiped with a mirror-cleaning paper directly or with a mirror-cleaning paper soaked with anhydrous alcohol, and the removal of the marks is observed. If the marks can be completely wiped off without leaving any traces, it is considered that the stain resistance is excellent. If the marks cannot be wiped off, it is considered that the stain resistance is poor. If the marks can be wiped off but with a small amount of traces, it is considered that the stain resistance is good.

[0038] The elongation at break test method is as follows: the material to be tested is cut into a sample with a size of 25 cm (length) and 2.5 cm (width), and the middle 5 cm length is marked. A KJ-1065 electronic tensile testing machine (Guangdong Kejian Instrument Co., Ltd.) is used with a 50 kg sensor, the clamp distance is set to 5 cm, and the speed is set to 10 cm / min. The elongation at break data is recorded.

[0039] The weather resistance test method is as follows: a Q-lab QUV ultraviolet accelerated aging tester is used, a UV lamp tube with a peak wavelength of 340 nm is used, and outdoor weather resistance simulation test is carried out. One test cycle includes two steps:

[0040] Step 1: temperature 60°C, irradiation intensity 0.71 Mw / cm2

[0041] Step 2: 4 hours of rain, temperature 40°C.

[0042] After repeating the above cycle for a total test time of 1000 hours,

[0043] (1) Observe the coating with the naked eye.

[0044] (2) Test the color change before and after weather resistance test with BYK-mac i colorimeter, and use ΔE to represent it.

[0045] If no cracks or local peeling are observed, and ΔE is less than 3, it indicates good outdoor weather resistance.

[0046] The transparency test method is as follows: the transparency of the composite film is represented by the transmission haze value, and the specific test method is as follows: the composite film is attached to the surface of a 1 mm thick glass plate, and the haze value is tested by a transmission haze instrument of BYK-Garden. The lower the haze value, the better the transparency.

[0047] Each component in the formula is calculated by weight.

[0048] The pressure-sensitive adhesive layer is a conventional pressure-sensitive adhesive formula used in the art, which specifically includes: acrylic acid, methyl acrylate, laurylene, , butadiene, toluene.

[0049] The coating of the heat insulation nanomaterial is a conventional heat insulation coating in the art, and the embodiment of the present application uses the following formula for heat insulation material slurry (cesium tungstate powder dispersion liquid, solid content 40%) 25 parts, diluent (1,6-hexanediol diacrylate (HDDA)) 50 parts, oligomer (polyurethane acrylate) 25 parts, initiator (Irgacure 651) 3 parts, antioxidant (Tinuvin P) 0.5 parts; the parts in the following examples all refer to weight parts.

[0050] Example 1

[0051] Under the condition of nitrogen atmosphere, 100 g of citric acid and 200 g of polyethylene glycol 600 were added into a round-bottom flask and mixed uniformly, heated to 150°C and stirred for 2 hours, then 0.1 g of p-toluenesulfonic acid was added, and the reaction was continued for 1 hour. The reaction system was vacuumed to remove small molecular byproducts until the weight of the reaction system did not change significantly, and then the reaction was stopped to obtain a polyester polyol;

[0052] In a round-bottom flask, the polyester polyol and polylactic acid polyol (purchased from Anhui Huaihai Biological Technology Co., Ltd., model HPB500) were mixed uniformly in DMF, heated to 120°C for 2 hours, then diphenylmethane diisocyanate (MDI) and a catalytic amount of dibutyltin dilaurate were added, and the reaction was continued at 100°C for 3 hours to obtain a prepolymer;

[0053] A chain extender butane-1,4-diol was added, and the reaction was continued at 100°C to obtain a polyurethane elastomer solution;

[0054] The polyurethane elastomer solution was coated on a PET release film by roll coating method, and after drying, a TPU base film was obtained. An acrylic pressure-sensitive adhesive solution was coated on the back of the base film to form a pressure-sensitive adhesive layer, and after drying, the release film was peeled off. A coating layer containing thermal insulation nanomaterials was coated on the surface of the base film, and then it was cured by ultraviolet light.

[0055] The composite film prepared in this example comprises a pressure-sensitive adhesive layer, a base film, and a thermal insulation nanomaterial layer stacked and combined in order from bottom to top. The thickness of the pressure-sensitive adhesive layer is 25 microns, the thickness of the base film is 100 microns, and the thickness of the thermal insulation nanomaterial layer is 10 microns.

[0056] The detection results are as follows:

[0057] (1) The adhesion of the polyurethane coating is good and it is not easy to fall off. The grid test reaches 5B;

[0058] (2) The elongation at break reaches 400%, the breaking strength reaches 44 MPa, and it has self-repairing function;

[0059] (3) Good scratch resistance, 0000# copper wire load 1 kg back and forth friction 1000 times or more without damage;

[0060] (4) Good weather resistance, after 1000 hours of repeated weathering cycle, no cracks or local peeling are observed on the surface of the coating, and ΔE = 2.2;

[0061] (5) The film is flat and has excellent leveling performance, and the 20-degree gloss is 96;

[0062] (6) Good transparency, the transmission haze value is 1.2, reaching the optical performance of PET.

[0063] Example 2

[0064] Under the condition of nitrogen atmosphere, 100 g of citric acid and 200 g of polyethylene glycol 600 were added into a round-bottom flask and mixed uniformly, heated to 150℃ and stirred for 2 hours, then 0.1 g of concentrated sulfuric acid was added, and the reaction was continued for 1 hour with stirring. The reaction system was vacuumed to remove small molecular byproducts until there was no significant change in the weight of the reaction system, and then the reaction was stopped to obtain a polyester polyol;

[0065] In a round-bottom flask, the polyester polyol and polylactic acid polyol (purchased from Anhui Huaihai Biological Technology Co., Ltd., model HPB1000) were mixed uniformly in DMF. After heating at 120℃ for 2 hours, hexamethylene diisocyanate and a catalytic amount of dibutyltin dilaurate were added, and the reaction was continued at 100℃ for 3 hours to obtain a prepolymer.

[0066] A chain extender, hexane-1,6-diol, was added, and the reaction was continued at 100℃ to obtain a polyurethane elastomer solution.

[0067] The polyurethane elastomer solution was coated on a PET release film by roll coating method, and after drying, a TPU base film was obtained. An acrylic pressure-sensitive adhesive solution was coated on the back of the base film to form a pressure-sensitive adhesive layer, and after drying, the release film was peeled off. A coating layer containing thermal insulation nanomaterials was then coated on the surface of the base film, and it was cured by ultraviolet light.

[0068] The composite film prepared in this example comprises a pressure-sensitive adhesive layer, a base film, and a thermal insulation nanomaterial layer stacked and combined from bottom to top. The thickness of the pressure-sensitive adhesive layer is 20 microns, the thickness of the base film is 50 microns, and the thickness of the thermal insulation nanomaterial layer is 20 microns.

[0069] The detection results are as follows:

[0070] (1) The adhesion of the polyurethane coating is good, and it is not easy to fall off, with a grid test of 5B;

[0071] (2) The elongation at break is 360%, the breaking strength is 33 MPa, and it has self-repairing function;

[0072] (3) Good scratch resistance, 0000# copper wire load 1 kg back and forth friction 1000 times or more without damage;

[0073] (4) Good weather resistance, after repeated weathering for 1000 hours, no cracks or local peeling were observed on the surface of the coating, and ΔE = 1.9;

[0074] (5) The film is flat, and the leveling performance is excellent, with a 20-degree gloss of 98;

[0075] (6) Good transparency, with a transmission haze value of 1.3, reaching the optical performance of PET.

Claims

1. A method for preparing a heat-insulating polyurethane composite film, comprising the following steps: (1) Under an inert atmosphere, citric acid and polyethylene glycol 600 are mixed evenly, heated and stirred, an acidic catalyst is added, and the reaction is stirred until the weight of the system does not change to obtain a polyester polyol; (2) In a solvent, under the action of a catalyst, polyester polyol and polylactic acid polyol are mixed evenly, and then polyisocyanate is added, and heated and stirred to react to obtain a prepolymer; (3) adding a chain extender and stirring the reaction to obtain a polyurethane elastomer solution; (4) coating the polyurethane elastomer solution on the PET release film and drying it to obtain the TPU base film; (5) Coating a pressure-sensitive adhesive layer on the back of the base film, baking and drying it, and then peeling off the release film; (6) Apply a coating containing thermal insulation nanomaterials on the surface of the base film and solidify it.

2. The preparation method according to claim 1, wherein In step (1), the acidic catalyst is one or more of p-toluenesulfonic acid, concentrated sulfuric acid, and concentrated hydrochloric acid; and the solvent is one or more of DMF, DMSO, THF, and methyl isobutyl ketone.

3. The preparation method according to claim 1, wherein In step (2), the catalyst is dibutyltin dilaurate, an organic bismuth catalyst, an organic zinc catalyst, or a tertiary amine catalyst; In step (2), the weight average molecular weight of the precursor is 1000-20000; In step (4), the polyurethane elastomer solution is preferably coated on the PET release film by roller coating, spraying or dipping.

4. The preparation method according to claim 1, wherein The polyisocyanate is selected from diphenylmethane diisocyanate, toluene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, methylene bis(4-cyclohexyl isocyanate) and mixtures thereof; In step (3), the weight average molecular weight of the polyurethane elastomer is 10,000-200,000.

5. The preparation method according to claim 1, wherein The chain extender is selected from one or more of ethane-1,2-diol, propane-1,3-diol, butane-1,4-diol, hexane-1,6-diol, diethylene glycol, and triethylene glycol.

6. The preparation method according to claim 1, wherein In step (5), the curing is baking curing or UV curing, preferably baking curing.

7. The preparation method according to claim 1, wherein The coating formula of the thermal insulation nanomaterial includes the following components in parts by weight: 20-25 parts of thermal insulation material slurry, 72-83 parts of film-forming material, and 0.5-0.6 parts of antioxidant; the thermal insulation material slurry is preferably a dispersion of lanthanum hexaboride, indium tin oxide, antimony tin oxide or cesium tungstate powder; when ultraviolet light curing is adopted, the film-forming material includes 50-55 parts of diluent, 20-25 parts of oligomer, and 2-3 parts of initiator; the diluent is preferably 1,6-hexanediol diacrylate, trimethylolpropane triacrylate or tripropylene glycol diacrylate; the oligomer is preferably polyurethane acrylate; when baking thermal curing is adopted, the film-forming material is polyacrylate or polyurethane.

8. A thermal insulating polyurethane composite film prepared by the preparation method according to any one of claims 1 to 7.

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