Thermoplastic polyurethane, polyurethane resin composition containing same, and molded product obtained therefrom

Abstract

A thermoplastic polyurethane is disclosed as a product obtained from a reaction mixture containing (A) a polycarbonate polyol having a number average molecular weight Mn of more than 500 and less than 2000, (B) an alicyclic polyisocyanate, and (C) a chain extender. The thermoplastic polyurethane has hard segments (HS) accounting for less than 40% by weight, based on the total weight of the thermoplastic polyurethane.

Description

[Technical Field]

[0001] The present invention relates to thermoplastic polyurethanes (TPUs), polyurethane resin compositions containing TPUs, and molded articles obtained from the polyurethane resin compositions.

[0002] Background technology Resin glass is widely used as an alternative to conventional silica-based glass, for example in vehicle windows, as it is lightweight and shatter-resistant.

[0003] Such resin glasses are usually made of a plastic substrate, such as polyacrylate or polycarbonate, and a hard coating layer, such as a silica-based or polymeric material, applied to the substrate, i.e., the plastic substrate is covered with a hard coating layer to protect it.

[0004] For example, Japanese Patent No. 5944069 (Patent Document 1) discloses a polymer substrate, particularly one with good transparency to visible light, coated with a silicon oxide layer as a hard coating layer. The silicon oxide layer is obtained by plasma enhanced chemical vapor deposition (PE-CVD).

[0005] Furthermore, JP 2020-69749 A (Patent Document 2) discloses a laminated panel including a polycarbonate substrate and a thermoplastic elastomer, such as polystyrene, polyurethane, polyester, polyamide, etc., as a hard coating layer. JP 2020-69749 A recommends the use of a primer layer to improve adhesion between the substrate and the hard coating layer.

[0006] In Japanese Patent No. 5944069, a silicon-based inorganic material is used as the hard coating layer, which must be deposited on the substrate using special deposition equipment, such as that for plasma-enhanced chemical vapor deposition.

[0007] On the other hand, Japanese Patent Application Laid-Open No. 2020-69749 proposes the use of a polymer film as a hard coating layer for resin glass. However, according to Japanese Patent Application Laid-Open No. 2020-69749, before applying the hard coating layer made of a polymer, a primer must be applied to the plastic substrate to maintain the hard coating layer on the substrate.

[0008] technical challenges However, known materials do not necessarily have good initial transparency, low initial haze, or sufficient abrasion resistance for hard coating layers, particularly for application on plastic glass, particularly for hard coating layers that meet the ECE R43 standard for glass components in vehicles. Furthermore, it is desirable that resins or resin compositions that can be applied as hard coating layers be economically produced according to a simple procedure.

[0009] It is therefore an object of the present invention to provide a thermoplastic polyurethane that has good transparency, low haze, and good abrasion resistance, and that can be easily applied as a hard coating layer on a polymer substrate. Preferably, the application of the thermoplastic polyurethane to the substrate can be carried out economically.

[0010] Means to solve the problem The inventors have determined that the object of the present invention is to (A) a polycarbonate polyol having a number average molecular weight Mn of more than 500 and less than 2000; (B) an alicyclic polyisocyanate, and (C) Chain extender A thermoplastic polyurethane as a product from a reaction mixture comprising: Thermoplastic polyurethanes having hard segments (HS) occupying less than 40% by mass based on the total mass of the thermoplastic polyurethane; or (A) a polycarbonate polyol having a number average molecular weight Mn of more than 500 and less than 3,000; (B) an alicyclic polyisocyanate, and (C) at least two chain extenders A thermoplastic polyurethane as a product from a reaction mixture comprising: Thermoplastic polyurethane having hard segments (HS) occupying less than 50% by mass based on the total mass of the thermoplastic polyurethane. It was discovered that this can be solved by

[0011] MODE FOR CARRYING OUT THE INVENTION [Thermoplastic polyurethane (TPU1)] The thermoplastic polyurethane (TPU1) of the present invention is (A1) a polycarbonate polyol having a number average molecular weight Mn of more than 500 and less than 2000 (referred to as polyol (A1) or component (A1)); (B1) cycloaliphatic polyisocyanates (referred to as polyisocyanates (B1) or component (B1)), and (C1) is a product from a reaction mixture (RM1) containing a chain extender (referred to as chain extender (C1) or component (C1)).

[0012] In a thermoplastic polyurethane (TPU1) obtained from a reaction mixture (RM1) containing polyol (A1), polyisocyanate (B1), and chain extender (C1), the hard segments (HS) account for less than 40% by weight of the total weight of the thermoplastic polyurethane. The thermoplastic polyurethane has hard segments (HS) and soft segments (SS). The hard segments (HS1), which serve as crosslinking points in the TPU, are prepared from polyisocyanate (B1) and chain extender (C1), while the soft segments (SS1), which serve as the polymer matrix, are prepared from polyol (A1). The resulting TPU1 has good initial transparency, indicated by a low initial haze value that can be maintained over a long period of time, and good abrasion resistance.

[0013] Details of the components (A1) to (C1) are as follows. [(A1) Polycarbonate polyol] Polycarbonate polyol (A1) is used to prepare TPU 1. Polyol (A) can be represented by the following formula (I): [ka]

[0014] In formula (I), n is in the range of 1 to 100, preferably in the range of 2 to 20, and R is a linear alkylene, preferably C2-C 16 Alkylene, more preferably C3-C 12 For the preparation of TPU1, a polycarbonate polyol (A1) having a number average molecular weight Mn in the range of more than 500 and less than 2000, more preferably in the range of 600 to 1600, and even more preferably in the range of 750 to 1200, is used. One or a combination of two or more polycarbonate polyols can be used as the polyol (A1).

[0015] In the present invention, the number average molecular weight Mn is determined as follows. Mn = (56100 x valence) / hydroxyl value In the above formula, the valence refers to the number of hydroxyl groups in the molecule. The valence of the polycarbonate diol in formula (1) is 2. Furthermore, the hydroxyl value is measured in accordance with JIS K 1557 (Method B).

[0016] [Method for producing polycarbonate polyol] The polyol (A1) of formula (I) may comprise an alcohol component, such as a C2-C 16 Alkylene diols, preferably C3-C 12 It can be produced by reacting an alkylene diol, more preferably a C4-C9 alkylene diol, with a carbonate diester component, such as dimethyl carbonate. Generally, the alcohol component and the carbonate diester component are used in a substantially equimolar ratio, and are usually subjected to a transesterification reaction in the presence of a catalyst.

[0017] The reaction temperature during the transesterification reaction is not particularly limited as long as it is a temperature at which a practical reaction rate can be obtained. The lower limit of the reaction temperature is usually 70°C, preferably 100°C, more preferably 130°C. The upper limit of the reaction temperature is usually 250°C, preferably 200°C, more preferably 190°C, even more preferably 180°C, and particularly preferably 170°C. The reaction pressure at the completion of the reaction is not particularly limited, but the upper limit at that time is usually 10 kPa, preferably 5 kPa, and more preferably 1 kPa.

[0018] The blend amount of polyol (A1) can be generally selected from 40 to 75 parts by weight, preferably 50 to 75 parts by weight, based on 100 parts by weight of all components in the reaction to obtain the thermoplastic polyurethane of the present invention. In the present invention, the blend amount of polyol (A1) does not have any adverse effect on the haze value. Furthermore, the use of polyol (A1) in the above blend ratio can shorten the cooling time of the TPU after injection molding.

[0019] The polyol (A1) has a linear structure, i.e., a linear structure without branching. However, a small amount, for example, less than 5 wt. % based on the total amount of the polyol (A1), of other types of polyols, such as branched polyols, may be included in the formulation for preparing TPU1. In the case of such branched polyols, R in formula (I) is a C3-C alkyl group having one or two C1-C3 alkyl side chains. 14 It may be alkylene.

[0020] Based on this technical understanding, good crystallinity is derived from linear polyols. Therefore, in the prior art, it has been believed that thermoplastic polyurethanes prepared using linear polyols, especially unbranched ones, are not recommended for obtaining products with good transparency. Contrary to this understanding, the use of polyol (A1) in the present invention contributes to imparting good initial transparency and small initial haze value to TPU1.

[0021] [(B1) Alicyclic polyisocyanate] As a component of TPU1, cycloaliphatic polyisocyanate (B1) is used. Examples of the alicyclic polyisocyanate (B1) include alicyclic diisocyanates such as cyclohexane diisocyanate, dicyclohexylmethane diisocyanate isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI), hydrogenated xylylene diisocyanate (hydrogenated XDI), and 1,4-bis(isocyanatomethyl)cyclohexane (1,4-H6XDI).

[0022] Among these, alicyclic diisocyanates having a completely or highly symmetric structure, such as 4,4'-dicyclohexylmethane diisocyanate, hydrogenated 1,4-xylylene diisocyanate, and 1,4-bis(isocyanatomethyl)cyclohexane, are preferred, and primary isocyanates, such as hydrogenated 1,4-xylylene diisocyanate and 1,4-bis(isocyanatomethyl)cyclohexane, are particularly preferred.

[0023] As polyisocyanate (B1) for preparing the thermoplastic polyurethane, one or more polyisocyanates can be used. Generally, the polyisocyanate (B1) is used in an amount such that there is completely or nearly equimolar NCO to OH groups in the polyol (A1), regardless of the functionality of the polyisocyanate (B1).

[0024] The concentration of the alicyclic polyisocyanate (B1) may suitably be in the range of 1.1 to 1.8 mol / kg, preferably in the range of 1.2 to 1.8, based on the total weight of components (A1) to (C1).

[0025] [(C1) Chain extender] A chain extender (C1) is used as a component of TPU1, and is at least one selected from the group consisting of 1,2-ethanediol, 1,3-propanediol (1,3-PD), 1,4-butanediol (1,4-BD), 1,5-pentanediol, 1,6-hexanediol (1,6-HD), 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol (1,9-ND), 3-methyl-1,5-pentanediol, 2-methyl-1,8-octanediol, diethylene glycol, and dipropylene glycol.

[0026] In other words, one or a combination of two or more of the above diols can be used as the chain extender (C1).

[0027] The use of 1,4-butanediol alone is preferred. Furthermore, a combination of 1,4-butanediol with one or more of 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,9-nonanediol (1,9-ND) is also preferred. This combination tends to improve the initial haze and abrasion resistance of the TPU.

[0028] [Hard segment (HS1)] The TPU1 of the present invention has a hard segment (HS1) content of less than 40% by mass, preferably 10 to 35% by mass, and particularly 15 to 30% by mass, based on the total mass of the TPU1. When the hard segment (HS1) content is less than 40% by mass, the resulting TPU1 has good abrasion resistance. Within the above range, not only the abrasion resistance of the TPU1 but also its chemical resistance and antifouling properties are improved. Furthermore, setting HS1 as described above allows for good processability, particularly with regard to moldability and film-forming properties.

[0029] The hard segment content can be controlled within the above range by appropriately selecting the blend amounts of the components in the reaction mixture (RM1) according to known methods. More specifically, the weight ratio of the polyol (A1) to the polyisocyanate (B1) can be in the range of (10:10) to (10:2), preferably in the range of (10:9) to (10:3), and particularly in the range of (10:7) to (10:5) ((A1):(B1)). At the same time, the weight ratio of the polyisocyanate (B1) to the chain extender (C1) can be in the range of (1:1) to (6:1), preferably in the range of (1:1) to (5:1), and particularly in the range of (1.5:1) to (3.5:1) ((B1):(C1)).

[0030] Another type of thermoplastic polyurethane (TPU2) is as good as TPU1 in terms of optical properties (initial transparency, initial haze) and mechanical strength (abrasion resistance).

[0031] [Thermoplastic polyurethane (TPU2)] The thermoplastic polyurethane (TPU2) of the present invention is (A2) a polycarbonate polyol having a number average molecular weight Mn of more than 500 and less than 3000 (referred to as polyol (A2) or component (A2)); (B2) cycloaliphatic polyisocyanates (referred to as polyisocyanates (B2) or component (B2)), and (C2) is a product from a reaction mixture (RM2) containing at least two chain extenders (referred to as chain extenders (C1) or components (C1)).

[0032] To prepare TPU2, two or more types of chain extenders are required in the reaction mixture (RM2) containing components (A2) to (C2).

[0033] Thermoplastic polyurethane (TPU2) is obtained from a reaction mixture (RM2) containing polyol (A2), polyisocyanate (B2), and chain extender (C2), where TPU2 accounts for less than 50% by weight based on the total weight of the thermoplastic polyurethane (TPU2). The thermoplastic polyurethane has hard segments (HS) and soft segments (SS). The hard segments (HS2), which serve as crosslinking points in the TPU, are prepared from polyisocyanate (B2) and chain extender (C2), while the soft segments (SS2), which serve as the polymer matrix, are prepared from polyol (A1). The resulting TPU2 has good initial transparency, indicated by a low initial haze value that can be maintained over a long period of time, and good abrasion resistance.

[0034] [(A2) Polycarbonate polyol] The polycarbonate polyol (A2) used in the preparation of TPU2 can be the same material as that of polyol (A1), except that the number average molecular weight Mn of polyol (A2) can be in the range of more than 500 and less than 3000. Other details, including the determination of the number average molecular weight Mn and examples of the preparation of polyol (A2), are also the same as those described for polyol (A1).

[0035] [(B2) Alicyclic polyisocyanate] The cycloaliphatic polyisocyanate (B1) that can be used in TPU1 is also used as the cycloaliphatic polyisocyanate (B2).

[0036] [(C2) Chain extender] At least two chain extenders (C2) are used as further components of TPU2 and are selected from the group consisting of 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,8-octanediol, diethylene glycol and dipropylene glycol.

[0037] It is preferred to use a smaller chain extender, such as 1,2-ethanediol or 1,3-propanediol (smaller CE), in combination with one or more larger chain extenders selected from 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol and 2-methyl-1,8-octanediol, diethylene glycol, and dipropylene glycol (larger CE). The blend ratio of the smaller CE to the larger CE is preferably within the range of (3:97) to (60:40), particularly within the range of (5:95) to (30:70).

[0038] [Hard Segment (HS2)] The TPU1 of the present invention has a hard segment (HS1) content of less than 50% by mass, preferably 10 to 40% by mass, and particularly 15 to 35% by mass, based on the total mass of TPU2. When the hard segment (HS2) content is less than 50% by mass, TPU2 with good abrasion resistance is obtained. Within the above range, not only the abrasion resistance of TPU2 but also its chemical resistance and antifouling properties are improved. Furthermore, setting HS2 as described above allows for good processability, particularly with regard to moldability and film-forming properties.

[0039] In the TPU (TPU1 or TPU2) of the present invention, the content of HS (HS1 or HS2) in the TPU is set by selecting the amounts of polyol (A), isocyanate (B), and chain extender (C) so as to satisfy the following formula, thereby selecting amounts within the above-mentioned ranges. HS content: {(moles of isocyanate (B) - moles of OH terminal groups of polyol (A)) * (mass of isocyanate (B)) + (mass of chain extender (C)} / (mass of isocyanate (B)) + mass of chain extender (C) + mass of polyol (A)) × 100

[0040] In other words, the hard segment content can be controlled within the above range by appropriately selecting the blend amounts of the components in the reaction mixture (RM2) according to known methods. More specifically, the weight ratio of the polyol (A2) to the polyisocyanate (B2) can be in the range of (10:10) to (10:2), preferably in the range of (10:8) to (10:4), and particularly in the range of (10:7) to (10:5) ((A2):(B2)). At the same time, the weight ratio of the polyisocyanate (B2) to the chain extender (C2) can be in the range of (1:1) to (6:1), preferably in the range of (1:1) to (4:1), and particularly in the range of (1.5:1) to (2.5:1) ((B2):(C2)).

[0041] Both thermoplastic polyurethanes, i.e., TPU1 and TPU2 of the present invention, have excellent optical properties despite slight differences in their formulations. In the present invention, a sample of TPU or TPU composition that is cooled to room temperature (25°C) under atmospheric pressure immediately after preparation and left in the same state for up to 88 hours without exposure to outdoor conditions is referred to as an "initial sample." The total transparency and haze values ​​of the initial sample are referred to as initial total transparency (TT) and initial haze. The TPU and TPU compositions of the present invention have excellent initial total transparency (TT) and low initial haze values. Furthermore, the thermoplastic polyurethanes of the present invention have good mechanical properties, such as sufficient hardness to protect the surface of plastic substrates as part of a resin glass, and improved abrasion resistance. Therefore, due to their good abrasion resistance, the thermoplastic polyurethanes maintain their initial transparency and initially low haze values ​​even after exposure to harsh environmental conditions.

[0042] [Thermoplastic polyurethane (TPU) manufacturing] Thermoplastic polyurethanes can be synthesized according to known methods using the above components (A) to (C) as raw materials, and optionally using a catalyst, a crosslinking agent, a crosslinking aid, etc. Polyurethanes can be produced by a batch process or a continuous process, both of which are carried out by known methods.

[0043] In continuous processes, polyurethanes are produced by a one-shot method, a prepolymer method, or the like, using, for example, a reactive extruder. Generally, the one-shot method is preferred due to production cost and time considerations. Meanwhile, semi-prepolymer and prepolymer methods may be used to advance the reaction and obtain a product of uniform quality and improved transparency. In these processes, components (A) to (C) are generally mixed continuously and generally reacted with each other immediately after mixing. When using an extruder such as a twin-screw extruder, components (A) to (C), as well as catalysts and / or additional materials, if any, are loaded into the extruder separately or in a premixed state. The temperature of the extruder can be raised to 120 to 240°C, preferably 150 to 220°C. The resulting polyurethane is then extruded, cooled, and pelletized.

[0044] From the viewpoint of durability and moldability, the weight-average molecular weight Mw of the thermoplastic polyurethane is preferably in the range of 80,000 to 250,000, more preferably 100,000 to 150,000. The molecular weight can generally be controlled by adjusting the molar ratio of the OH-containing component (the sum of the polyol and the chain extender) to the polyisocyanate component. The molecular weight can also be controlled by adding a monool (monoalcohol) such as methanol, ethanol, propanol, butanol, or 2-ethylhexyl alcohol to the reaction system.

[0045] The molecular weight of polyurethane is determined using GPC (gel permeation chromatography), using polystyrene as the standard polymer and THF as the eluent, and preparing a sample solution with a concentration of approximately 0.1%. The measurement was performed using a Tosoh HLC-8220 GPC at a flow rate of 0.35 ml / min and a temperature of 40°C for a measurement time of 15 minutes. The same applies to the following examples.

[0046] As mentioned above, the polyurethanes according to the present invention can be initially prepared, typically in pellet form, but can also be in powder form. Further TPU processing can then be carried out by known methods such as injection molding, calendering, extrusion, etc. In particular, when forming TPU sheets for use as hard coatings on resin substrates, it is preferred to use a twin-screw extruder.

[0047] Further materials such as catalysts, crosslinking agents and crosslinking aids can be used in the production of polyurethanes according to the present invention. The types of applicable materials are not particularly limited as long as the object of the present invention can be achieved.

[0048] Specific examples of catalysts include tin-containing organometallic compounds such as dibutyltin dilaurate (DBTDL), dioctyltin dilaurate, dibutyltin diacetate, and tin(II) bis(2-ethylhexanoate); titanate esters; zirconium compounds; bismuth-containing organometallic compounds such as bismuth carboxylates, including bismuth(III) neodecanoate and bismuth(III) 2-ethylhexanoate; iron-containing organometallic compounds; amine catalysts such as triethylamine, triethylenediamine, N-methylimidazole, N-ethylmorpholine, and 1,8-diazabicyclo[5,4,0]-7-undecene (DBU); potassium acetate; and phosphorus compounds such as tributylphosphine, phospholene, and phospholene oxide. These may be used alone or in combination.

[0049] The total amount of catalyst used is preferably 5% by mass or less, more preferably in the range of 0.001% by mass to 2% by mass, based on the total mass of components (A) to (C).

[0050] The thermoplastic polyurethane of the present invention can be molded without further additives. The molded product obtained exhibits excellent transparency and abrasion resistance. Furthermore, if any modification is required, it is possible to further add additives to the TPU.

[0051] In the present invention, the transparency is evaluated using the total light transmittance (Tt) in accordance with JIS K 7361-1:1997 and the haze in accordance with JIS K 7136:2000.

[0052] [Thermoplastic polyurethane composition] As mentioned above, one or more additives can be added to the finished TPU. Such additives include antioxidants, light stabilizers, UV absorbers, nucleating agents, surface modifiers, optical brighteners, lubricants, hydrolysis inhibitors, crosslinkers, antistatic agents, antiblocking agents, heat stabilizers, flame retardants, heat resistance improvers, weather resistance improvers, reaction retarders, plasticizers, conductivity improvers, antibacterial agents, antifungal agents, inorganic and organic fillers, fiber reinforcing agents, and colorants. Thermoplastic polyurethane compositions with various properties can be obtained by using these additives depending on the application or intended use.

[0053] Additives to impart weather resistance may be added to the polyurethane, such as antioxidants, light stabilizers, ultraviolet light inhibitors, or a combination of two or more thereof, depending on the intended use of the polyurethane composition.

[0054] An antioxidant is preferably added to the polyurethane or polyurethane composition when the molded product is used outdoors or exposed to other environmental conditions where oxidative deterioration is expected. The type of antioxidant is not particularly limited, and known materials can be used.

[0055] Additionally, phosphorus-based antioxidants (e.g., tris(2,4-di-tert-butylphenyl)phosphite (Irgafos™ 168, manufactured by BASF Japan Ltd.) and vitamin E-based antioxidants (e.g., 3,4-dihydro-2,5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl)-2H-benzopyran-6-ol (Irganox™ E 201, manufactured by BASF Japan Ltd.) can also be used.

[0056] The use of amine-based antioxidants is not preferred if the polyurethane or polyurethane composition is not to be colored.

[0057] The antioxidant can be used in an amount of 0.01 to 2% by weight, preferably 0.1 to 1% by weight, and especially 0.1 to 0.5% by weight, based on the total weight of the thermoplastic polyurethane.

[0058] Furthermore, as described above, an ultraviolet absorber may be added to the polyurethane composition. The type of ultraviolet absorber is not particularly limited, and known materials can be used. Specific examples of ultraviolet absorbers include cinnamic acid esters, diphenylcyanoacrylate, formamidine, benzylidene malonate, diaryl butadiene, triazine-based UV absorbers, and benzotriazole-based UV absorbers (e.g., Tinuvin™ 329 manufactured by BASF Japan Ltd.).

[0059] As described above, the polyurethane of the present invention exhibits excellent transparency with low haze that can be maintained for a long period of time without relying on ultraviolet absorbers. Therefore, ultraviolet absorbers are not usually added to polyurethanes. In contrast, when a molded product is constantly exposed to strong ultraviolet rays, such as when installed outdoors, it is preferable to use an ultraviolet absorber.

[0060] Similarly, as described above, a light stabilizer may be added to the polyurethane of the present invention. The type of light stabilizer is not particularly limited, and known materials can be used. A hindered amine light stabilizer (HALS) may be used as the light stabilizer. Examples of commercially available HALS stabilizers are described in "Plastic Additives Handbook" (5th Edition, H. Zweifel, Hanser Publishing Co., Munich, 2001, pp. 123-136). The number average molecular weight of the hindered amine light stabilizer is preferably 500 g / mol to 10,000 g / mol, more preferably 1,000 g / mol to 5,000 g / mol. Particularly preferred hindered amine light stabilizers are bis(1,2,2,6,6-pentamethylpiperidyl) sebacate (Tinuvin™ 765, manufactured by BASF Japan Ltd.), the condensation product of 1-hydroxyethyl-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid (Tinuvin™ 622, manufactured by BASF Japan Ltd.), and polymeric sterically hindered amine (Chisorb™ 622LT, manufactured by Double Bond Chemical Ind., Co., Ltd.). The condensation product of 1-hydroxyethyl-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid (Tinuvin™ 622) is particularly preferred. The concentration of the HALS compound used is preferably 0.01 to 3% by mass, more preferably 0.1 to 2.0% by mass, and even more preferably 0.1 to 1.0% by mass, based on the mass of the polyurethane.

[0061] Furthermore, a nucleating agent can be added to the polyurethane of the present invention. The type of nucleating agent is not particularly limited. Known nucleating agents can be used. Specific examples include dibenzylidene sorbitol-based nucleating agents (e.g., Millad™ NX8000, manufactured by Milliken Chemical Co. Ltd.), metal benzoate-based nucleating agents, phosphate ester-based nucleating agents, and rosin-based nucleating agents. The blend ratio of the nucleating agent can be 0.3% by mass or less, more preferably 0.1 to 0.25% by mass, based on the mass of the polyurethane. When the amount of nucleating agent added is 0.3% by mass or less, the resulting polyurethane molded product will have excellent haze value and yellowing resistance.

[0062] Surface modifiers can be used as further additives in the polyurethane of the present invention. The type of surface modifier is not particularly limited. Known surface modifiers, such as waxes or lubricants, can be used. Specific examples include petroleum-derived hydrocarbon waxes, such as ozokerite, paraffin wax, Montan acid ester wax, animal wax, beeswax, shellac wax, wool wax, vegetable waxes, such as carnauba wax, candelilla wax, and rice wax, fatty acid amide waxes, such as ethylene bisstearamide (EBS), N,N'-ethylene bisoleamide (EBO), or erucamide, polyolefin waxes, such as polyethylene wax, polypropylene wax, Fischer-Tropsch wax, polyethylene oxide wax, and modified polyolefin waxes, such as graft or copolymer polyolefins. Furthermore, acrylic polymer lubricants (e.g., Metabrene L1000, manufactured by Mitsubishi Chemical Corporation) can be used as surface modifiers. In the present invention, Montan acid ester waxes (e.g., Licolub WE4, manufactured by Clariant Japan Co., Ltd.) and acrylic polymer lubricants are particularly preferred. As a result, products molded from polyurethane have improved lubricity and good mold release properties. Also, by adjusting the amount of additive, bleeding over time can be suppressed.

[0063] As mentioned above, the surface modifiers can be added singly or in combination of two or more. The amount of the surface modifier can be 0.01 to 1% by mass, preferably 0.01 to 0.5% by mass, based on the mass of the polyurethane.

[0064] Known colorants can be added to the polyurethane composition of the present invention. The type of colorant is not particularly limited. A blue pigment can be used as a bluing agent to reduce the initial yellowness. The appearance of the polyurethane composition can be further improved by using a fluorescent whitening agent in combination.

[0065] [Preparation of polyurethane composition (TPU composition)] To prepare a TPU composition, i.e., a mixture of the above-mentioned TPU and additional components, a predetermined amount of one or more additives is appropriately metered into the TPU, followed by mixing using known mixing equipment, including kneaders and mixers. The TPU is typically processed into pellet or powder form using known methods such as injection molding, calendaring, or extrusion. For example, the TPU is fed into a post-extruder, where it is typically kneaded and melted at temperatures of about 150-230°C in an ambient atmosphere. The TPU is then extruded into the desired shape. Twin-screw mixers, continuous single-screw or twin-screw mixers with continuous kneading extruders can be used.

[0066] The TPU composition may be in the form of a powder, flake, rod, sheet or block, or may be in the form of pellets or granules, for example, by strand cutting or underwater cutting.

[0067] [Manufacturing of molded products] The TP composition thus obtained is molded into a product of the desired shape using, for example, a suitable molding device or mold. Any known molding device or mold can be used as long as it can mold the polyurethane composition into the desired shape.

[0068] The uses of the molded products obtained from the TPU composition are not particularly limited. The TPU of the present invention has excellent transparency that can be well maintained even after being exposed to environmental stress for a long time, and has good hardness, so it is particularly applicable as a hard coating film for vehicle or building windows. Further uses of the TPU of the present invention include molded articles such as exterior parts of automobiles, motorcycles, bicycles, ships, trains, or airplanes.

[0069] [Substrate] The TPU or TPU composition as such of the present invention can be applied to a substrate, for example, as a hard coating film on the substrate. Examples of the substrate include resins such as polycarbonate resin, polymethyl methacrylate resin, methyl methacrylate resin, transparent acrylonitrile-butadiene-styrene resin, transparent polystyrene resin, transparent epoxy resin, polyarylate, polysulfone, polyethersulfone, transparent nylon resin, transparent polybutylene terephthalate, transparent fluororesin, poly-4-methylpentene-1, transparent phenoxy resin, polyimide resin, and transparent phenol resin.

[0070] Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto. Unless otherwise specified, "parts" and "%" are based on mass.

[0071] Examples

[0072] [Examples 1-1 to 1-⑨, and 2-1 to 2-3, and Comparative Examples 2-1 to 2-5, and 2-1 to 2-4] <TPU Synthesis> For the examples and comparative examples, the following operations were carried out using the materials shown in Table 1 in the indicated amounts.

[0073] The polyol (A) and chain extender (C) were weighed into a cylindrical 2-L metal container with a temperature range of 90-95°C. Antioxidants, light stabilizers, UV absorbers, lubricants, nucleating agents, and catalysts were added, and the mixture was stirred at 200-300 rpm until uniformly mixed. Next, polyisocyanate (B), preheated to 50°C, was loaded into the container, and the mixture was stirred until the temperature reached 105°C.

[0074] After reaching 105°C, the resulting liquid mixture was transferred to a Teflon container and then annealed at 95°C for 15 hours to increase the molecular weight into a polymer. This resulted in a TPU resin in the form of a slab. The slab was cut and crushed to form flakes.

[0075] The flakes were fed from a feeder into a twin-screw extruder (Werner & Pfleiderer, ZSK30, 30 mm diameter). The temperature in the region from the hopper to the die head was set at 180 to 210°C. The flakes were melt-mixed and extruded into strands while the screws were rotating at 100 to 110 rpm. The strands were placed in a water bath, cooled there, and then cut with a pelletizer to continuously obtain a TPU composition produced in uniform pellet form.

[0076] <Molding of test samples> The above TPU composition was subjected to injection molding using an injection molding machine (TM130F2, manufactured by Toyo Machinery & Metal Co., Ltd.) under the following conditions. The molding temperature at the nozzle tip of the injection molding machine was set to a temperature in the range of 200 to 210°C. The cylinder temperature was gradually decreased by 5°C toward the hopper. The temperature at the bottom of the hopper was set to 180 to 190°C. The mold temperature was set to 25°C.

[0077] After heating and melting the TPU composition, a 40 mm diameter screw was used, and the injection speed was 10% (11 mm / sec) and the injection pressure was 90 kgf / (1130 kgf / cm 2 ) was injected at 80kgf / (1070kgf / cm 2After cooling the mold by holding it at the pressure of ) for 40 seconds, a plate-shaped molded product with dimensions of 160 mm (length) × 105 mm (width) × 2 mm (thickness) was obtained. All test samples were found to have excellent surface smoothness without dents or scratches on the surface. These samples were used to evaluate the Shore A hardness. The same samples were also used to evaluate the optical properties.

[0078] The test samples were found to have excellent surface smoothness without dents or scratches on the surface. Here, after cooling to 25°C under atmospheric pressure and then holding for 88 hours under the same conditions, the test samples in the initial state (initial state samples) were used for the following tests.

[0079] <Determination of HS content (%)> The hard segment (HS) of the initial state samples was set to have the values listed in Table 1 by weighing the polyol (A), isocyanate (B), and chain extender (C) so as to satisfy the following formula. Content of HS: {((mol of isocyanate (B) - mol of OH end groups of polyol (A)) * (mass of isocyanate (B)) + (mass of chain extender (C))) / ((mass of isocyanate (B)) + mass of chain extender (C) + mass of polyol (A))} × 100

[0080] [Evaluation of optical properties] <Evaluation of total light transmittance (TT)> In accordance with JIS K 7361-1:1997, the total light transmittance of the initial state samples was evaluated. The obtained value was described in Table 1 as the initial total light transmittance, that is, "initial TT".

[0081] <Evaluation of initial haze> The haze value of the initial state samples was evaluated in accordance with JIS K 7136:2000, and the measured value was described in Table 1 as "initial haze".

[0082] Generally, the transparency of a sample is affected by the haze. Generally, a sample having an initial total light transmittance of 85% or more and an initial haze of 10% or less is acceptable for a product requiring transparency.

[0083] Good transparency is observed when the initial total light transmittance is 85% or more, particularly 90% or more, and particularly 95% or more, and the initial haze is 5% or less, particularly 3.5 or less, and particularly 3.0 or less. The above initial haze value is applicable when the initial sample has a thickness of 2 mm or less, particularly 150 μm or less.

[0084] <Evaluation of the difference in haze value after Taber abrasion test> To evaluate the abrasion resistance of the samples, the samples were subjected to a Taber abrasion test at 500 revolutions in accordance with ASTM D1044 (Taber 500). The haze value of the sample after the Taber abrasion test was measured in accordance with JIS K 7136:2000. The difference (%) (Δ haze) between the haze value of the sample after the Taber abrasion test and the initial haze was obtained. ΔHaze (%) = Haze (%) of sample after Taber 500 - Initial haze (%) The results are shown as "Taber 500 (Δ haze)" in Table 1. Needless to say, the lower the Δ haze value, the better the abrasion resistance.

[0085] [Evaluation of mechanical properties] <Shore A hardness evaluation> To determine the Shore A hardness, the test samples were subjected to measurements in accordance with JIS K 7311-1995. The Shore A hardness was measured using a Type A durometer on three stacked test samples, with a total thickness of 6 mm for each example and comparative example. The evaluation results are shown in Table 1.

[0086] [Table 1]

[0087] The materials listed in Table 1 are as follows: Polycarbonate polyol: 1,6-hexanediol polycarbonate with number average molecular weight Mn of 500, 1000, 2000 and 3000 H6XDI: 1,4-bis(isocyanatomethyl)cyclohexane 1,3-PD: 1,3-propanediol 1,4-BD: 1,4-butanediol 1,9-ND: 1,9-nonanediol

[0088] Table 2 shows the weight ratio of the polyol (A) and the weight ratio of the chain extender (C), calculated from the mass of the polyol (A) and the mass of the chain extender (C) in Table 1.

[0089] [Table 2]

[0090] As can be seen from Table 1, the TPU compositions of the present invention not only exhibit excellent optical properties, but also good mechanical properties.

[0091] It is understood that modifications and variations of the novel polyurethanes and compositions described herein can be made, provided they come within the scope of the appended claims or the equivalents thereof.

Claims

1. (A) a polycarbonate polyol having a number average molecular weight Mn of more than 500 and less than 2000; (B) an alicyclic polyisocyanate, and (C) Chain extender A thermoplastic polyurethane as a product from a reaction mixture comprising: A thermoplastic polyurethane having hard segments (HS) that account for less than 40% by mass based on the total mass of the thermoplastic polyurethane.

2. (A) a polycarbonate polyol having a number average molecular weight Mn of more than 500 and less than 3,000; (B) an alicyclic polyisocyanate, and (C) at least two chain extenders A thermoplastic polyurethane as a product from a reaction mixture comprising: A thermoplastic polyurethane having hard segments (HS) that account for less than 50% by mass based on the total mass of the thermoplastic polyurethane.

3. The polycarbonate polyol (A) is C ２ -C １６ 3. The thermoplastic polyurethane of claim 1, which is the reaction product of an alkylene diol and a carbonate diester.

4. The thermoplastic polyurethane according to claim 1, wherein the chain extender (C) is at least one selected from the group consisting of 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,8-octanediol, diethylene glycol, and dipropylene glycol.

5. The thermoplastic polyurethane according to claim 2, wherein the chain extender (C) comprises a combination of at least two selected from the group consisting of 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,8-octanediol, diethylene glycol, and dipropylene glycol.

6. 6. The thermoplastic polyurethane of claim 1, 2, 4, or 5, wherein the concentration of the cycloaliphatic polyisocyanate (B) is in the range of 1.2 to 1.8 mol / kg, based on the total weight of the polycarbonate polyol (A), the cycloaliphatic polyisocyanate (B), and the chain extender / chain extenders (C).

7. The thermoplastic polyurethane according to claim 1 or 2, and an antioxidant A polyurethane resin composition comprising:

8. A molded article obtained from a polyurethane composition according to any one of the resin compositions of claim 7.

9. 9. The molded product of claim 8 in the form of a sheet to be applied to a substrate for resin glazing.

10. 10. The molded product of claim 9, wherein the 2 mm thick sheet has an initial haze value of 5% or less.

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