Thermoplastic polyurethane resin suitable for producing vehicle wrapping film

Abstract

To provide a thermoplastic polyurethane resin which is formed by a polymerization reaction of a reaction mixture and is suitable for producing a vehicle wrapping film.SOLUTION: A reaction mixture contains an isocyanate material, a polyol material, and a chain extender. A benzene ring is not contained in a chemical structure of the isocyanate material. The isocyanate material is at least one selected from the group consisting of dicyclohexylmethane diisocyanate (H12MDI), hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI). The polyol material is at least one selected from the group consisting of polycaprolactone polyol and polyether polyol. The chain extender is a diol chain extender.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a thermoplastic polyurethane resin, and in particular to a thermoplastic polyurethane resin suitable for producing car wrap films. [Background technology]

[0002] Thermoplastic polyurethane resins (TPU materials) used in conventional car wrap films tend to yellow over time and lose physical properties due to hydrolysis. Furthermore, the finished product after coating processing of conventional TPU materials for car wrap films is prone to crystal points and poor transparency, resulting in a lower quality of car wrap. Summary of the Invention [Problem to be solved by the invention]

[0003] Therefore, in view of the fact that the above-mentioned problems can be improved, the inventors conducted intensive research and applied scientific theory, and as a result, arrived at the present invention as a method that is rational in design and can effectively improve the above-mentioned problems.

[0004] The technical problem to be solved by the present invention is to provide a thermoplastic polyurethane resin suitable for producing car wrap films in response to the shortcomings of the prior art. [Means for solving the problem]

[0005] In order to solve the above technical problems, one technical means adopted by the present invention is to provide a thermoplastic polyurethane resin suitable for producing car wrap films, which is formed by polymerization of a reaction mixture. The reaction mixture includes an isocyanate material having no benzene ring in its chemical structure, a polyol material, and a chain extender which is a diol chain extender. The isocyanate material is dicyclohexylmethane diisocyanate (H 12The polyol material is at least one selected from the group consisting of polycaprolactone polyols and polyether polyols.

[0006] Preferably, the isocyanate material comprises a first isocyanate component and a second isocyanate component, the first isocyanate component being dicyclohexylmethane diisocyanate (H 12 MDI), and the second isocyanate component is at least one of hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI).

[0007] Preferably, the first weight ratio of the first isocyanate component is 70% to 98%, and the second weight ratio of the second isocyanate component is 2% to 30%, with the total weight of the first isocyanate component and the second isocyanate component being 100%.

[0008] Preferably, the polyol material is a polycaprolactone polyol formed by a polymerization reaction between a low molecular weight diol and a caprolactone monomer, and the low molecular weight diol is a diol having carbon numbers of C2 to C8.

[0009] Preferably, the low molecular weight diol is 1,6-hexanediol, the number average molecular weight (Mn) of the polyol material is 1,000 g / mol to 5,000 g / mol, and the chain extender is 1,4-butanediol (14BG).

[0010] Preferably, the NCO / OH equivalent ratio between the isocyanate group (-NCO) in the isocyanate material and the hydroxyl group (-OH) in the polyol material is 0.998 to 1.015.

[0011] Preferably, the reaction mixture further comprises a hydrolysis inhibitor which is a carbodiimide, and a chain terminator which is a long chain fatty alcohol having carbon numbers from C12 to C18.

[0012] Preferably, the chain terminator is at least one selected from the group consisting of stearyl alcohol, lauryl alcohol, and oleic alcohol.

[0013] Preferably, when the total weight of the reaction mixture is 100 parts by weight, the amount of the isocyanate material used is 20 parts by weight to 60 parts by weight, the amount of the polyol material used is 20 parts by weight to 60 parts by weight, the amount of the chain extender used is 5 parts by weight to 20 parts by weight, the amount of the hydrolysis inhibitor used is 0.1 parts by weight to 1 part by weight, and the amount of the chain terminator used is 0.01 parts by weight to 0.3 parts by weight.

[0014] Preferably, the melt index of the thermoplastic polyurethane resin is 1 g / 10 min / 200°C to 5 g / 10 min / 200°C. Effect of the Invention

[0015] An advantageous effect of the present invention is that the thermoplastic polyurethane resin suitable for producing the car wrap film of the present invention can effectively improve problems of conventional TPU materials such as yellowing over time, deterioration of physical properties due to hydrolysis, susceptibility to crystal points, and poor transparency after coating processing by "combining isocyanate materials and polyol materials and selecting them", and can effectively improve the quality of the car wrap film. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Certain specific embodiments will be described below, and those skilled in the art can understand the advantages and effects of the present invention based on the contents disclosed in this specification. The present invention can be implemented or applied by other different specific embodiments, and various modifications and changes can be made to each detail in this specification based on different perspectives and applications, without departing from the concept of the present invention. The technical contents according to the present invention will be described in more detail based on the following embodiments, but the disclosed contents do not limit the scope of protection of the present invention. It should be understood that, although various materials or parameters may be described in this specification using terms such as "first", "second", and "third", these materials or parameters are not limited by these terms. In addition, the term "or" used in this specification may include any one or more combinations of the items listed in relation to each other according to the actual situation.

[0017] [Thermoplastic polyurethane resin] As an object of the present invention, the present invention provides a thermoplastic polyurethane resin (TPU resin), particularly a thermoplastic polyurethane resin suitable for the manufacture of car wrap films.

[0018] Thermoplastic polyurethane resins according to embodiments of the present invention are formed by polymerization of a reaction mixture that includes an isocyanate material, a polyol material, a chain extender, an anti-hydrolysis agent, and a chain terminator.

[0019] It should be noted that in this embodiment, the reaction mixture may further include, but is not limited to, a UV absorber, a photo-stabilizer, other auxiliary additive components (such as antioxidants), and / or other solvent components.

[0020] The amount of the isocyanate material used is 20 parts by weight to 60 parts by weight, preferably 25 parts by weight to 55 parts by weight, and particularly preferably 30 parts by weight to 50 parts by weight, based on 100 parts by weight of the total weight of the reaction mixture. The amount of the polyol material used is 20 parts by weight to 60 parts by weight, preferably 25 parts by weight to 55 parts by weight, and particularly preferably 30 parts by weight to 50 parts by weight, based on 100 parts by weight of the total weight of the reaction mixture. The amount of the chain extender used is 5 parts by weight to 20 parts by weight, preferably 7 parts by weight to 18 parts by weight, and particularly preferably 9 parts by weight to 16 parts by weight, based on 100 parts by weight of the total weight of the reaction mixture, but the present invention is not limited thereto.

[0021] More specifically, the amount of the hydrolysis inhibitor is 0.1 to 1 part by weight, preferably 0.2 to 0.9 parts by weight, and particularly preferably 0.3 to 0.8 parts by weight. The amount of the chain extender is 0.01 to 0.3 parts by weight, and particularly preferably 0.05 to 0.2 parts by weight. The amount of the ultraviolet absorber is 0.1 to 0.5 parts by weight, and preferably 0.2 to 0.5 parts by weight. The amount of the light stabilizer is 0.1 to 0.5 parts by weight, and preferably 0.2 to 0.5 parts by weight. The other auxiliary additive components and / or other solvent components are the remaining amounts, but the present invention is not limited thereto.

[0022] As a material, the isocyanate material is dicyclohexylmethane diisocyanate (4,4'-diisocyanato dicyclohexylmethane, H 12 The isocyanate may be at least one selected from the group consisting of MDI (also called 4,4'-dicyclohexylmethane diisocyanate), hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI).

[0023] Dicyclohexylmethane diisocyanate (H 12 The chemical structure of MDI is as follows: [ka]

[0024] The chemical structure of hexamethylene diisocyanate (HDI) is shown below. [ka]

[0025] The chemical structure of isophorone diisocyanate (IPDI) is shown below. [ka]

[0026] Of particular note is the isocyanate material used in the embodiments of the present invention (e.g., H 12 None of the chemical structures of MDI, HDI, or IPDI contain a benzene ring.

[0027] More specifically, dicyclohexylmethane diisocyanate (H 12 The chemical structure of hexamethylene diisocyanate (MDI) contains two cyclohexyls. The chemical structure of hexamethylene diisocyanate (HDI) contains one hexamethylene. Also, the chemical structure of isophorone diisocyanate (IPDI) contains one cyclohexyl. However, none of the chemical structures of the isocyanate materials contain a benzene ring (the state of the carbon-carbon bond in the benzene ring is between a single bond and a double bond). The isocyanate material used in the embodiment of the present invention can at least improve the problem of yellowing over time in conventional thermoplastic polyurethane resins.

[0028] In one preferred embodiment of the present invention, the isocyanate material may be a mixture of two isocyanates, which improves the problem of yellowing over time in thermoplastic polyurethane and the occurrence of crystal points due to coating processing, while simultaneously improving the scratch resistance and soft touch of the car wrap film.

[0029] More specifically, the isocyanate material includes a first isocyanate component and a second isocyanate component. The first isocyanate component is dicyclohexylmethane diisocyanate (H 12 MDI), and the second isocyanate component is at least one of hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI).

[0030] The total weight of the first isocyanate component and the second isocyanate component is taken as 100%, and the first isocyanate component (H 12 The first weight ratio of MDI) is 70% to 98%, preferably 80% to 98%, and particularly preferably 86.2% to 94%.

[0031] The second weight ratio of the second isocyanate component (HDI and / or IPDI) is 2% to 30%, preferably 2% to 20%, and particularly preferably 6% to 13.8%. 12 MDI) is the major isocyanate component and the second isocyanate component (HDI and / or IPDI) is a minor addition of the isocyanate component.

[0032] It is worth noting that the first isocyanate component (H 12 MDI) does not contain a benzene ring, but contains two positionally symmetrical cyclohexyls, which makes it possible to improve the problem of yellowing over time that occurs in conventional thermoplastic polyurethanes, as well as the crystal points that occur during coating processing, while maintaining the physical properties required for car wrap films.

[0033] In addition, the first isocyanate component (H 12 The molecular structure of the second isocyanate component (HDI and / or IPDI) is more flexible than aromatic diisocyanates (e.g., MDI) commonly used in conventional technology, and therefore the scratch resistance of the final car wrap film can be effectively improved. In addition, the second isocyanate component (HDI and / or IPDI) also makes the car wrap film softer to the touch and provides better scratch resistance.

[0034] More specifically, the polyol material of the present embodiment is at least one selected from the group consisting of polycaprolactone polyol (PCL) and polyether polyol, and is preferably polycaprolactone polyol.

[0035] Here, the polycaprolactone polyol is formed by a polymerization reaction between a low molecular diol and a caprolactone monomer, where the low molecular diol is a diol having carbon numbers of C2 to C8.

[0036] In one preferred embodiment of the present invention, the low molecular weight diol is a C6 diol, that is, the low molecular weight diol is 1,6-hexanediol.

[0037] The number average molecular weight (Mn) of the polyol material is 1,000 g / mol to 5,000 g / mol, and preferably 1,000 g / mol to 3,000 g / mol.

[0038] Of note, when the polycaprolactone polyol satisfies the above parameters, it can impart excellent transparency, hydrolysis resistance and processability to the final formed thermoplastic polyurethane resin (eg, TPU particles).

[0039] The low molecular weight diol is preferably 1,6-hexanediol. 1,6-hexanediol provides better processability to TPU particles than other diols (e.g., 1,4-butanediol). The thermoplastic polyurethane resin according to the embodiment of the present invention is synthesized with polycaprolactone polyol, and its physical properties (e.g., light transmittance) are superior to those of polyether polyol. In addition, polyester polyol is generally poor in hydrolysis resistance, and is not adopted in the present invention.

[0040] It is particularly noteworthy that in one embodiment of the present invention, the NCO / OH equivalent ratio of the isocyanate group (-NCO) in the isocyanate material to the hydroxyl group (-OH) in the polyol material is preferably 0.998 to 1.015, particularly preferably 1.012 to 1.015, so that the finally formed thermoplastic polyurethane resin (e.g., TPU particles) has a stable melt index change rate.

[0041] More specifically, in one embodiment of the present invention, the type of the chain extender is a diol chain extender. The chain extender is preferably 1,4-butanediol (14BG). The amount of the chain extender used is 5 to 20 parts by weight, preferably 7 to 18 parts by weight, and particularly preferably 9 to 16 parts by weight. The chain extender can improve a specific physical property (e.g., hardness, heat resistance, or hydrolysis resistance) of the final polymer.

[0042] More specifically, in one embodiment of the present invention, the material of the hydrolysis inhibitor is preferably carbodiimide. The amount of the hydrolysis inhibitor used is 0.1 to 1 part by weight, preferably 0.2 to 0.9 parts by weight, and particularly preferably 0.3 to 0.8 parts by weight. The hydrolysis inhibitor can effectively improve the hydrolysis resistance of the final polymer.

[0043] To explain further, in one embodiment of the present invention, the chain terminator material is preferably a long-chain fatty alcohol (monohydric alcohol) having a carbon number of C12 to C18. For example, the chain terminator may be at least one selected from the group consisting of stearyl alcohol (a long-chain fatty alcohol having a carbon number of C18), lauryl alcohol (a long-chain fatty alcohol having a carbon number of C12), and oleic alcohol (a long-chain unsaturated fatty alcohol having a carbon number of C18), but the present invention is not limited thereto. The amount of the chain terminator used is 0.01 to 0.3 parts by weight, and preferably 0.05 to 0.2 parts by weight. Here, the chain terminator can control the melt index (MI) and molecular weight of the finally formed thermoplastic polyurethane resin (e.g., TPU particles).

[0044] It is particularly noteworthy that the melt index of the thermoplastic polyurethane resin is controlled to 1 g / 10 min / 200° C. to 5 g / 10 min / 200° C., preferably 1.5 g / 10 min / 200° C. to 4 g / 10 min / 200° C., and particularly preferably 1.6 g / 10 min / 200° C. to 3.1 g / 10 min / 200° C. The weight average molecular weight (Mw) of the thermoplastic polyurethane resin is 120,000 g / mol to 280,000 g / mol, preferably 150,000 g / mol to 250,000 g / mol, and particularly preferably 185,000 g / mol to 223,000 g / mol.

[0045] It should be noted that the "melt index" in this embodiment is the weight of a thermoplastic polyurethane resin extruded from a standard opening at 200°C in 10 minutes in a melt flow rate tester. The unit is g / 10 min / 200°C. The melt index indicates the fluidity of a resin in a molten state. The larger the melt index, the lower the molecular weight and the better the fluidity.

[0046] The molecular weight (weight average molecular weight, Mw) of the thermoplastic polyurethane resin was obtained by analysis using gel permeation chromatography (GPC).

[0047] More specifically, the UV absorber is intended to improve the UV resistance (i.e., improve the QUV level) of the final thermoplastic polyurethane resin. In one embodiment of the present invention, the UV absorber is at least one selected from the group consisting of benzotriazoles, benzophenones, triazines, and combinations thereof. In one specific example, the UV absorber is UV-328 UV absorber (2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol), but the present invention is not limited thereto. It is noteworthy that the UV-328 UV absorber is a phenolic benzotriazole compound.

[0048] In one embodiment of the present invention, the light stabilizer is a low molecular weight hindered amine light stabilizer (HALS). For example, the light stabilizer may be LS770 hindered amine light stabilizer (bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate), but the present invention is not limited thereto.

[0049] Based on the materials and compounding ratios of each component in the thermoplastic polyurethane resin, the thermoplastic polyurethane resin (e.g., TPU particles) exhibits good performance in the following specific physical properties:

[0050] <Workability> After the TPU particles are coated by the extruder (T-die), the film appearance has no coarse particles or crystal points, that is, the thermoplastic polyurethane resin has good processability.

[0051] <Light transparency> An injection-molded test piece having a thickness of 2 mm has a visible light transmittance of 90% or more, which means that the thermoplastic polyurethane resin has good light transmittance.

[0052] <Weather resistance> The color difference ΔE after irradiating a hot press molded test piece having a thickness of 0.2 mm with QUV 340 nm light for 1000 hours is 5 or less, and preferably 3 or less. That is, the thermoplastic polyurethane resin has good weather resistance, that is, it has a property of being unlikely to yellow over time. The measuring device may be a QUV ultraviolet weather resistance tester, and the measuring method may be ASTM G154-16.

[0053] <Hydrolysis resistance> After storing a hot press molded test piece having a thickness of 0.2 mm in an environment at a temperature of 60°C and a relative humidity of 90 RH% for 28 days, the tensile strength of the test piece is maintained at a rate of 80% or more. In other words, the thermoplastic polyurethane resin has good hydrolysis resistance.

[0054] [Method of manufacturing thermoplastic polyurethane resin] The above description is about the characteristics of the thermoplastic polyurethane resin material according to the embodiment of the present invention, and the manufacturing method of the thermoplastic polyurethane resin material according to the embodiment of the present invention will be described below. The manufacturing method includes steps S110, S120, and S130, but the present invention is not limited thereto.

[0055] In the step S110, a mixing step is carried out, which includes forming a reaction mixture by charging an isocyanate material, a polyol material, a chain extender, an anti-hydrolysis agent, and other components added in small amounts into a mixer based on predetermined usage amounts and mixing them. Examples of the other components added in small amounts include an ultraviolet absorber, a photo-stabilizer, etc.

[0056] In step S120, a reaction process is carried out, which includes introducing the reaction mixture into an extruder (e.g., a twin-screw reaction extruder) to carry out a polymerization reaction between the isocyanate material and the polyol material, and terminating the polymerization reaction by introducing a chain terminator into the reaction mixture in a rear section of the extruder to form a thermoplastic polyurethane resin.

[0057] Here, in order to ensure that the polymerization reaction proceeds sufficiently, the extrusion temperature of the twin-screw reactive extruder is preferably set to, for example, 150° C. to 250° C., but the present invention is not limited thereto.

[0058] In the step S130, the thermoplastic polyurethane resin is diced in an aqueous environment to form particulate thermoplastic polyurethane resin (i.e., TPU particles), which is a granulation step.

[0059] Here, the total weight of the reaction mixture is 100 parts by weight, and the amount of the isocyanate material used may be 20 parts by weight to 60 parts by weight, the amount of the polyol material used may be 20 parts by weight to 60 parts by weight, the amount of the chain extender used may be 5 parts by weight to 20 parts by weight, the amount of the hydrolysis inhibitor used may be 0.1 parts by weight to 1 part by weight, the amount of the chain terminator used may be 0.01 parts by weight to 0.3 parts by weight, the amount of the UV absorber used may be 0.1 parts by weight to 0.5 parts by weight, and the amount of the light stabilizer used may be 0.1 parts by weight to 0.5 parts by weight, but the present invention is not limited thereto.

[0060] [Measurement of experimental data] The present invention will be described in detail below with reference to Examples 1 to 4 and Comparative Examples 1 and 2. However, these Examples are provided to aid in understanding the present invention, and the present invention is not limited thereto. The experimental conditions and measurement results of Examples 1 to 4 and Comparative Examples 1 to 2 are shown in Table 1. Here, Examples 1 to 4 are preferred examples of the present invention, and Comparative Examples 1 to 2 were used as a control group to prove that Examples 1 to 4 have superior effects.

[0061] Example 1: 40g of isocyanate (94% H 12 MDI and 6% HDI), 39g of polyol (polycaprolactone polyol, Mn=2,000g / mol), 11.4g of chain extender (14BG), 0.3g of hydrolysis inhibitor (carbodiimide), 0.1g of chain terminator (stearyl alcohol), 0.3g of ultraviolet absorber (UV328), and 0.3g of light stabilizer (LS770) were introduced into a twin-screw reactive extruder to mix and react. Here, the chain terminator was introduced into the rear section of the twin-screw reactive extruder to terminate the polymerization reaction and form a thermoplastic polyurethane resin, and then the resin was granulated to form TPU particles. Here, the NCO / OH equivalent ratio of the isocyanate and polyol was 1.012, the weight average molecular weight (Mw) of the TPU particles was 185,000g / mol, and the melt index MI was 2.5g / 10min / 200℃.

[0062] Example 2: 40.2 g of isocyanate (86.2% H 12 MDI and 13.8% HDI), 39.4g polyol (polycaprolactone polyol, Mn=2,000g / mol), 11.5g chain extender (14BG), 0.5g hydrolysis inhibitor (carbodiimide), 0.1g chain terminator (stearyl alcohol), 0.3g UV absorber (UV328), and 0.3g light stabilizer (LS770) were introduced into a twin-screw reactive extruder to mix and react. Here, the chain terminator was introduced into the rear section of the twin-screw reactive extruder to stop the polymerization reaction and form a thermoplastic polyurethane resin, and then the resin was granulated to form TPU particles. Here, the NCO / OH equivalent ratio between the isocyanate and the polyol was 1.015, the weight average molecular weight (Mw) of the TPU particles was 223,000 g / mol, and the melt index MI was 3.1 g / 10 min / 200°C.

[0063] Example 3: 40.5 g of isocyanate (91.4% H 12 MDI and 8.6% IPDI), 38.6g of polyol (polycaprolactone polyol, Mn=2,000g / mol), 11.3g of chain extender (14BG), 0.5g of hydrolysis inhibitor (carbodiimide), 0.1g of chain terminator (stearyl alcohol), 0.3g of ultraviolet absorber (UV328), and 0.3g of light stabilizer (LS770) were introduced into a twin-screw reactive extruder to mix and react. Here, the chain terminator was introduced into the rear section of the twin-screw reactive extruder to stop the polymerization reaction and form a thermoplastic polyurethane resin, and then the resin was granulated to form TPU particles. Here, the NCO / OH equivalent ratio between the isocyanate and the polyol was 1.015, the weight average molecular weight (Mw) of the TPU particles was 219,000 g / mol, and the melt index MI was 2.4 g / 10 min / 200°C.

[0064] Example 4: 40.5 g of isocyanate (91.4% H 12 MDI and 8.6% IPDI), 38.9g of polyol (polycaprolactone polyol, Mn=2,000g / mol), 11.3g of chain extender (14BG), 0.5g of hydrolysis inhibitor (carbodiimide), 0.1g of chain terminator (stearyl alcohol), 0.3g of ultraviolet absorber (UV328), and 0.3g of light stabilizer (LS770) were introduced into a twin-screw reactive extruder to mix and react. Here, the chain terminator was introduced into the rear section of the twin-screw reactive extruder to stop the polymerization reaction and form a thermoplastic polyurethane resin, and then the resin was granulated to form TPU particles. Here, the NCO / OH equivalent ratio between the isocyanate and the polyol was 1.015, the weight average molecular weight (Mw) of the TPU particles was 206,000 g / mol, and the melt index MI was 1.6 g / 10 min / 200°C.

[0065] Comparative Example 1: 40.8g of isocyanate (containing 100% MDI), 48g of polyol (polycaprolactone polyol, Mn=2,000g / mol), 11.2g of chain extender (14BG), 0.5g of hydrolysis inhibitor (carbodiimide), 0.1g of chain terminator (stearyl alcohol), 0.3g of ultraviolet absorber (UV328), and 0.3g of light stabilizer (LS770) were introduced into a twin-screw reactive extruder to mix and react. Here, the chain terminator was introduced into the rear section of the twin-screw reactive extruder to stop the polymerization reaction and form a thermoplastic polyurethane resin, and then the resin was granulated to form TPU particles. Here, the NCO / OH equivalent ratio between the isocyanate and the polyol was 1.012, the weight average molecular weight (Mw) of the TPU particles was 206,000 g / mol, and the melt index MI was 4.0 g / 10 min / 200°C.

[0066] Comparative Example 2: 47.7g of isocyanate (containing 100% MDI), 39.9g of polyol (polyether polyol, Mn=1,800g / mol), 12.4g of chain extender (14BG), 0.2g of hydrolysis inhibitor (carbodiimide), 0.1g of chain terminator (stearyl alcohol), 0.3g of ultraviolet absorber (UV328), and 0.3g of light stabilizer (LS770) were introduced into a twin-screw reactive extruder to mix and react. Here, the chain terminator was introduced into the rear section of the twin-screw reactive extruder to stop the polymerization reaction and form a thermoplastic polyurethane resin, and then the resin was granulated to form TPU particles. Here, the NCO / OH equivalent ratio between the isocyanate and the polyol was 1.015, the weight average molecular weight (Mw) of the TPU particles was 206,000 g / mol, and the melt index MI was 2.9 g / 10 min / 200°C.

[0067] Next, the physicochemical properties of the thermoplastic polyurethane resins produced in Examples 1 to 4 and Comparative Examples 1 and 2 were measured to obtain the physicochemical properties of those thermoplastic polyurethane resins. For example, processability (coating appearance), visible light transmittance (%), color difference (ΔE) by weather resistance QUV measurement, and hydrolysis resistance (tensile strength retention rate %) can be mentioned. The measurement method is as follows. The measurement results are shown in Table 1 below.

[0068] <Workability> After the TPU particles were coated by the extruder (T-die), the appearance of the film was observed to see if there were any coarse particles or crystal points. If the film did not have any coarse particles or crystal points, the processability of the TPU particles was good.

[0069] <Transparency> The visible light transmittance of the injection molded test piece having a thickness of 2 mm was measured using a light transmittance meter, and the visible light transmittance (%) was recorded.

[0070] <Weather resistance> A 0.2 mm thick TPU specimen was prepared by hot pressing, and the 0.2 mm thick hot press molded specimen was irradiated with QUV 340 nm light for 1000 hours, after which the ΔE*ab (CIE color difference) of the molded specimen was measured.

[0071] <Hydrolysis resistance> A hot press molded test piece having a thickness of 0.2 mm was stored in an environment at a temperature of 60° C. and a relative humidity of 90 RH% for 28 days, and then the retention rate of the tensile strength of the test piece was measured.

[0072] [Table 1-1] [Table 1-2]

[0073] [Consideration of measurement results] According to the above experimental results, the TPU particles according to Examples 1 to 4 have good processability, without coarse particles or crystal points in the appearance of the film even after coating by an extruder (T-die). The injection molded test piece having a thickness of 2 mm has a visible light transmittance of 91.5% to 92.1%, which is a good light transmittance. The TPU hot press molded test piece having a thickness of 0.2 mm has a color difference (ΔE) of 0.98 to 1.34 after 1000 hours of irradiation with QUV 340 nm light, which has excellent weather resistance, that is, it has a property of not easily yellowing over time. After storing the hot press molded test piece having a thickness of 0.2 mm in an environment at a temperature of 60°C and a relative humidity of 90 RH% for 28 days, the tensile strength retention rate of the test piece was 80.3% to 82.3%, which has good hydrolysis resistance.

[0074] Generally speaking, the TPU particles according to Examples 1 to 4 contain H as an isocyanate material. 12By primarily using MDI in combination with small amounts of HDI and IPDI, and further compounding it with polycaprolactone polyol, it has achieved a light transmittance of over 90% and also has excellent weather resistance (resistance to yellowing) and hydrolysis resistance.

[0075] Aromatic MDI was used as the isocyanate material for all of the TPU particles in Comparative Examples 1 and 2. The color difference ΔE of Comparative Examples 1 and 2 was 20.6 to 26.4, which was poorer in weather resistance than Examples 1 to 4, and yellowing was likely to occur over time. Furthermore, the hydrolysis resistance of Comparative Example 1 was also poorer than Examples 1 to 4. Comparative Example 2 was provided with a slightly lower light transmittance (90%) than Examples 1 to 4 by using polyether polyol.

[0076] [Advantageous Effects of the Embodiments] An advantageous effect of the embodiment of the present invention is that the thermoplastic polyurethane resin suitable for producing the car wrap film of the present invention can effectively improve the problems of conventional TPU materials, such as yellowing over time, deterioration of physical properties due to hydrolysis, susceptibility to crystal points, and poor transparency after coating processing, by "combining isocyanate materials and polyol materials and selecting them", and can effectively improve the quality of the car wrap film.

[0077] The above disclosure is merely a preferred embodiment of the present invention, and the scope of the claims of the present invention is not limited thereto. Therefore, all equivalent technical modifications made by utilizing the contents of the specification and drawings of the present invention are included in the scope of the claims of the present invention.

Claims

1. A thermoplastic polyurethane resin formed by polymerization of a reaction mixture, the thermoplastic polyurethane resin being suitable for producing a car wrap film, The reaction mixture comprises: An isocyanate material that does not contain a benzene ring in its chemical structure; A polyol material; a chain extender which is a diol chain extender; The isocyanate material is dicyclohexylmethane diisocyanate (H １２ At least one selected from the group consisting of hexamethylene diisocyanate (MDI), hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI); The thermoplastic polyurethane resin, wherein the polyol material is at least one selected from the group consisting of polycaprolactone polyols and polyether polyols.

2. The isocyanate material includes a first isocyanate component and a second isocyanate component, the first isocyanate component being dicyclohexylmethane diisocyanate (H １２ 10. The thermoplastic polyurethane resin of claim 1, wherein the first isocyanate component is at least one of hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI).

3. 3. The thermoplastic polyurethane resin of claim 2, wherein a first weight ratio of the first isocyanate component is 70% to 98% and a second weight ratio of the second isocyanate component is 2% to 30%, where the total weight of the first isocyanate component and the second isocyanate component is 100%.

4. 2. The thermoplastic polyurethane resin according to claim 1, wherein the polyol material is a polycaprolactone polyol formed by a polymerization reaction between a low molecular weight diol and a caprolactone monomer, and the low molecular weight diol is a diol having a carbon number of C2 to C8.

5. The thermoplastic polyurethane resin of claim 4, wherein the low molecular weight diol is 1,6-hexanediol, the number average molecular weight (Mn) of the polyol material is 1,000 g / mol to 5,000 g / mol, and the chain extender is 1,4-butanediol (14BG).

6. The thermoplastic polyurethane resin according to claim 1, wherein the NCO / OH equivalent ratio of the isocyanate group (-NCO) in the isocyanate material to the hydroxyl group (-OH) in the polyol material is 0.998 to 1.

015.

7. 2. The thermoplastic polyurethane resin of claim 1, wherein the reaction mixture further comprises a hydrolysis inhibitor which is a carbodiimide and a chain terminator which is a long chain fatty alcohol having from C12 to C18 carbon atoms.

8. 8. The thermoplastic polyurethane resin according to claim 7, wherein the chain terminator is at least one selected from the group consisting of stearyl alcohol, lauryl alcohol, and oleic alcohol.

9. The thermoplastic polyurethane resin according to claim 7, wherein, relative to a total weight of the reaction mixture of 100 parts by weight, the amount of the isocyanate material used is 20 parts by weight to 60 parts by weight, the amount of the polyol material used is 20 parts by weight to 60 parts by weight, the amount of the chain extender used is 5 parts by weight to 20 parts by weight, the amount of the hydrolysis inhibitor used is 0.1 parts by weight to 1 part by weight, and the amount of the chain terminator used is 0.01 parts by weight to 0.3 parts by weight.

10. The thermoplastic polyurethane resin according to any one of claims 1 to 9, having a melt index of 1 g / 10 min / 200 ° C to 5 g / 10 min / 200 ° C.

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