Polyurethane

Abstract

The present invention provides a polyurethane that decomposes in water upon irradiation with ultraviolet light and a method for producing the same, as well as a polyol useful as a raw material for the polyurethane and a method for producing the same. The polyurethane is obtained by polymerizing a polyol and a polyisocyanate compound, wherein the polyol is represented by formula (I): TIFF0007732698000024.tif28159 (in the formula, R 1 and R 2 and each independently represent an alkylene group which may have a substituent.

Description

[Technical Field]

[0001] The present invention relates to polyurethanes. More specifically, the present invention relates to polyurethanes that can be prepared using bio-derived itaconic acid as a raw material and a method for producing the same, as well as to polyols that are useful as raw materials for the polyurethanes and a method for producing the same. [Background technology]

[0002] Polyurethane is a polymer of polyol and polyisocyanate, and is used in a wide range of fields, such as cushioning materials for sofas and the like, wall materials, flooring materials, heat insulating materials for household electrical appliances, coating agents, and adhesives (see, for example, Patent Document 1).

[0003] Generally, used polyurethane is disposed of by burying it in soil, incineration, etc. However, when polyurethane is buried in soil, there is a risk of causing deterioration of the soil, and when polyurethane is incinerated, there is a risk of generating toxic gases that cause air pollution (see, for example, Non-Patent Document 1).

[0004] Furthermore, coated fertilizers for plants that use polymers such as polyurethane as a coating shell allow the fertilizer components to gradually dissolve, thereby eliminating the need for additional fertilization, and the fertilizer components dissolve in accordance with plant growth, allowing for a reduction in the amount of fertilizer used, and therefore the use of such coated fertilizers has been increasing in recent years. However, on the other hand, there are concerns about the adverse impact on the natural environment when the coating shells of coated fertilizers are released into the ocean as microplastics, etc. (see, for example, Non-Patent Document 2).

[0005] For these reasons, there has been an urgent need in recent years to develop polymers such as polyurethanes that can be decomposed by ultraviolet rays contained in sunlight. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2019-019211 [Non-patent literature]

[0007] [Non-Patent Document 1] Yinglu Sun et al. Polymer, 2021, 233, 124208 [Non-patent document 2] J. Lian et al. Journal of Cleaner Production, 2021, 318, 128571 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made in view of the above-mentioned conventional techniques, and an object of the present invention is to provide a polyurethane that decomposes in water upon irradiation with ultraviolet light and a method for producing the same, as well as a polyol that is useful as a raw material for the polyurethane and a method for producing the same. [Means for solving the problem]

[0009] The present invention provides (1) A polyurethane obtained by polymerizing a polyol and a polyisocyanate compound, wherein the polyol is represented by the formula (I):

[0010] [ka]

[0011] (In the formula, R 1 and R 2 each independently represents an alkylene group which may have a substituent. A polyurethane characterized in that the polyol is represented by (2) A method for producing polyurethane by polymerizing a polyol and a polyisocyanate compound, wherein the polyol is a compound represented by the formula (I):

[0012] [ka]

[0013] (In the formula, R 1 and R 2 each independently represents an alkylene group which may have a substituent. and polymerizing the polyol with a polyisocyanate compound. (3) Formula (I):

[0014] [ka]

[0015] (In the formula, R 1 and R 2 each independently represents an alkylene group which may have a substituent. and a polyol represented by (4) Formula (II):

[0016] [ka]

[0017] (In the formula, R 1 represents an alkylene group which may have a substituent. and a carboxypyrrolidone compound represented by formula (III): H2N-R 2 -NH2(III) (In the formula, R 2 represents an alkylene group which may have a substituent. and a diamine represented by formula (I):

[0018] [ka]

[0019] (In the formula, R 1 and R 2 is the same as above) A method for producing a polyol represented by Regarding. [Effects of the Invention]

[0020] According to the present invention, there are provided a polyurethane that decomposes in water upon irradiation with ultraviolet light and a method for producing the same, as well as a polyol that is useful as a raw material for the polyurethane and a method for producing the same. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a graph showing the H-NMR spectrum of 1-(3-hydroxypropyl)-5-oxopyrrolidine-3-carboxylic acid obtained in Example 1. [Figure 2] 1 is a graph showing the ESI-MS spectrum of 1-(3-hydroxypropyl)-5-oxopyrrolidine-3-carboxylic acid obtained in Example 1. [Figure 3] 1 is a graph showing the 1H-NMR spectrum of the polyol obtained in Example 2. [Figure 4] 1 is a graph showing an ESI-MS spectrum of the polyol obtained in Example 2. [Figure 5] 1 is a graph showing 1H-NMR spectra of the polyurethanes obtained in Examples 3 to 6. [Figure 6] 1 is a graph showing the IR spectra of the polyurethanes obtained in Examples 3 to 6. [Figure 7] 1 is a photograph, substituted for a drawing, showing the change over time of the polyurethane obtained in Example 1 when the polyurethane is irradiated with ultraviolet light. DETAILED DESCRIPTION OF THE INVENTION

[0022] The polyurethane of the present invention is a polyurethane obtained by polymerizing a polyol and a polyisocyanate compound.

[0023] The polyol has the formula (I):

[0024] [ka]

[0025] (In the formula, R 1 and R 2 each independently represents an alkylene group which may have a substituent. The polyol is a polyol represented by formula (II):

[0026] [ka]

[0027] (In the formula, R 1 is the same as above) and a carboxypyrrolidone compound represented by formula (III): H2N-R 2 -NH2(III) (In the formula, R 2 is the same as above) The compound can be prepared by reacting the compound with a diamine represented by the formula:

[0028] In the present invention, R 1 and R 2 are each independently an alkylene group which may have a substituent. Examples of the alkylene group include alkylene groups having 2 to 12 carbon atoms, such as an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a 2-ethylhexylene group, a decylene group, an undecylene group, and a dodecylene group, but the present invention is not limited to these examples.

[0029] Examples of the substituent include alkoxy groups having 1 to 4 carbon atoms, such as methoxy, ethoxy, propoxy, and butoxy; hydroxyl groups; halogen atoms, such as fluorine, chlorine, bromine, and iodine; cyano groups; and nitrile groups, but the present invention is not limited to these examples. Among these substituents, alkoxy groups having 1 to 4 carbon atoms, hydroxyl groups, and halogen atoms are preferred. The halogen atom is preferably a fluorine atom, chlorine atom, bromine atom, or iodine atom, more preferably a fluorine atom, chlorine atom, or bromine atom, and even more preferably a fluorine atom or chlorine atom.

[0030] (1) Carboxypyrrolidone compounds The carboxypyrrolidone compound is a compound represented by formula (II) as described above, and is a useful compound as a raw material for the polyurethane of the present invention.

[0031] The carboxypyrrolidone compound can be prepared using itaconic acid (salt) and an amino alcohol. Itaconic acid (salt) refers to itaconic acid and / or an itaconate salt. Itaconic acid and an itaconate salt may be used alone or in combination.

[0032] Itaconic acid is readily available commercially from, for example, Fuso Chemical Co., Ltd., Iwata Chemical Co., Ltd., Cargill, etc. Itaconic acid may be produced using fungi such as Aspergillus terreus, or may be synthesized using petroleum as a raw material. Among these, itaconic acid produced using fungi such as Aspergillus terreus has the advantage of being more environmentally friendly than itaconic acid synthesized using petroleum as a raw material.

[0033] Examples of the itaconate include alkali metal itaconates such as sodium itaconate and potassium itaconate, and ammonium itaconate, but the present invention is not limited to these examples. Among the itaconates, alkali metal itaconates are preferred, and sodium itaconate is more preferred.

[0034] The amino alcohol can be obtained by reacting an alkylamine with an alkylene oxide, and can also be easily obtained commercially, for example, from Tokyo Chemical Industry Co., Ltd. Among the amino alcohols, an amino alcohol having an amino group and a hydroxyl group at the molecular terminal is preferred. Examples of the amino alcohol having an amino group and a hydroxyl group at the molecular terminal include those represented by the formula (IV): HO-R 1 -NH2(IV) (In the formula, R 1 is the same as above) Examples of the amino alcohols represented by formula (IV) include alkanolamines having 1 to 12 carbon atoms, such as ethanolamine, propanolamine, butanolamine, pentanolamine, hexanolamine, heptanolamine, octanolamine, 2-ethylhexanolamine, 10-amino-1-decanol, and 12-amino-1-dodecanol, but the present invention is not limited to these examples.

[0035] Since itaconic acid (salt) and amino alcohol react in stoichiometric amounts, the amount of amino alcohol per mole of itaconic acid (salt) is theoretically 1 mole. However, the amount of itaconic acid (salt) may be in excess of the amount of amino alcohol, or the amount of amino alcohol may be in excess of the amount of itaconic acid (salt). The amount of amino alcohol per mole of itaconic acid (salt) is usually preferably 0.9 to 1.1 moles.

[0036] The reaction temperature when reacting the itaconic acid (salt) with the amino alcohol is preferably about 80 to 120°C, from the viewpoint of efficiently reacting the itaconic acid (salt) with the amino alcohol. The atmosphere when reacting the itaconic acid (salt) with the amino alcohol may be air or an inert gas such as nitrogen gas or argon gas. The reaction time between the itaconic acid (salt) and the amino alcohol varies depending on the reaction temperature and cannot be determined in general, so it is usually preferably the time required for sufficient production of a carboxypyrrolidone compound.

[0037] By reacting the itaconic acid (salt) with the amino alcohol in the manner described above, the carboxypyrrolidone compound represented by formula (II) can be obtained.

[0038] (2) Preparation of polyol As described above, the polyol of the present invention is a compound represented by formula (I). The polyol can be obtained by reacting a carboxypyrrolidone compound represented by formula (II) with a diamine represented by formula (III).

[0039] Examples of diamines represented by formula (III) include 1,2-ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 2-methyl- ... pentanediamine, 3-methyl-1,5-pentanediamine, 3-ethyl-1,5-pentanediamine, 2-methyl-1,6-hexanediamine, 2-ethyl-1,6-hexanediamine, 3-methyl-1,6-hexanediamine, 3-ethyl-1,6-hexanediamine, 2-methyl-1,8-octanediamine, 3-methyl-1,8-octanediamine, 4-methyl-1,8-octanediamine, 2 Examples of alkylene diamines include alkylene diamines having 2 to 12 carbon atoms in the alkylene group, such as 2-ethyl-1,8-octanediamine, 3-ethyl-1,8-octanediamine, 4-ethyl-1,8-octanediamine, 3-propyl-1,8-octanediamine, 2-butyl-1,8-octanediamine, 3-butyl-1,8-octanediamine, 4-butyl-1,8-octanediamine, 2-methyl-1,9-nonanediamine, 3-methyl-1,9-nonanediamine, 4-methyl-1,9-nonanediamine, 2-ethyl-1,9-nonanediamine, 3-ethyl-1,9-nonanediamine, 4-ethyl-1,9-nonanediamine, 2-propyl-1,9-nonanediamine, 3-propyl-1,9-nonanediamine, and 4-propyl-1,9-nonanediamine, but the present invention is not limited to these examples. These diamines may be used alone or in combination of two or more. From the viewpoint of obtaining a polyurethane that is both decomposable in water and durable, the diamine is preferably an alkylene diamine having an alkylene group with 2 to 12 carbon atoms, and more preferably at least one diamine selected from the group consisting of 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptadiamine, 1,8-octanediamine, 1,9-nonanediamine, and 1,10-decanediamine.

[0040] Since the carboxypyrrolidone compound and the diamine react in stoichiometric amounts, the amount of the diamine per mole of the carboxypyrrolidone compound is theoretically 1 mole. However, the amount of the carboxypyrrolidone compound may be in excess of the amount of the diamine, or the amount of the diamine may be in excess of the amount of the carboxypyrrolidone compound. The amount of the diamine per mole of the carboxypyrrolidone compound is usually preferably 0.9 to 1.1 moles.

[0041] The reaction temperature when reacting the carboxypyrrolidone compound with the diamine is preferably about 100 to 150°C from the viewpoint of efficiently reacting the carboxypyrrolidone compound with the diamine. The atmosphere when reacting the carboxypyrrolidone compound with the diamine may be air or an inert gas such as nitrogen gas or argon gas. The reaction time between the carboxypyrrolidone compound and the diamine varies depending on the reaction temperature and cannot be determined in general, so it is usually preferably the time required for sufficient production of the polyol represented by formula (I).

[0042] By reacting the carboxypyrrolidone compound with the diamine in the manner described above, the polyol represented by formula (I) can be obtained.

[0043] (3) Preparation of polyurethane The polyurethane can be obtained by reacting the polyol represented by formula (I) with a polyisocyanate compound.

[0044] The polyisocyanate compound means an isocyanate compound having at least two isocyanate groups.

[0045] Examples of the polyisocyanate compound include those represented by the formula (V): R 3 -(NCO) n (V) (In the formula, R3 is a monovalent aromatic group, a monovalent aliphatic group, or a monovalent alicyclic hydrocarbon group, and n is R 3 This indicates the number of isocyanate groups (NCO groups) bonded to the Examples of the polyisocyanate include polyisocyanates represented by the following formula:

[0046] Specific examples of polyisocyanates represented by formula (V) include aliphatic polyisocyanates, aromatic polyisocyanates, and alicyclic polyisocyanates. These polyisocyanates may be used alone or in combination of two or more. These polyisocyanates may also be modified. Examples of the modified products include prepolymer-type modified products, which are reaction products with polyols, isocyanurate-modified products, urea-modified products, carbodiimide-modified products, allophanate-modified products, and biuret-modified products, but the present invention is not limited to these examples. Among polyisocyanates, aliphatic polyisocyanates are preferred from the viewpoint of improving the solubility in water of polyurethanes prepared using the polyisocyanates.

[0047] Examples of aliphatic polyisocyanates include 1,6-hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and lysine diisocyanate, but the present invention is not limited to these examples. These aliphatic polyisocyanates may be used alone or in combination of two or more. All of these aliphatic polyisocyanates can be suitably used in the present invention. Among these aliphatic polyisocyanates, 1,6-hexamethylene diisocyanate is preferred from the viewpoint of improving the solubility of polyurethane in water.

[0048] The aromatic polyisocyanate is a polyisocyanate having an aromatic group. Examples of aromatic polyisocyanates include xylylene diisocyanate, diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, triphenylmethane triisocyanate, tolylene diisocyanate, naphthylene diisocyanate, phenylene diisocyanate, and methylene diphenyl diisocyanate, but the present invention is not limited to these examples. These aromatic polyisocyanates may be used alone or in combination of two or more. Among these aromatic polyisocyanates, xylylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, and tolylene diisocyanate are preferred.

[0049] Examples of alicyclic polyisocyanates include dicyclohexylmethane diisocyanate, isophorone diisocyanate, cyclohexane diisocyanate, and norbornane diisocyanate, but the present invention is not limited to these examples. These alicyclic polyisocyanates may be used alone or in combination of two or more. Among these alicyclic polyisocyanates, dicyclohexylmethane diisocyanate, isophorone diisocyanate, and cyclohexane diisocyanate are preferred, and dicyclohexylmethane diisocyanate is more preferred.

[0050] Examples of polyisocyanate compounds that can be suitably used in the present invention include aliphatic polyisocyanates such as 1,6-hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and lysine diisocyanate; aromatic polyisocyanates such as xylylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, tolylene diisocyanate, and hexamethylene diisocyanate; and alicyclic polyisocyanates such as dicyclohexylmethane diisocyanate, isophorone diisocyanate, and cyclohexane diisocyanate.

[0051] When reacting the polyol with the polyisocyanate compound, it is desirable to adjust the ratio of the polyol to the polyisocyanate compound so that the isocyanate index (the ratio of the total isocyanate groups in the polyisocyanate compound to the total hydroxyl groups in the polyol [total NCO groups / total OH groups] × 100) is preferably 80 to 200, more preferably 90 to 150.

[0052] When the polyol and the polyisocyanate compound are reacted, the polyol and the polyisocyanate compound may be dissolved in an organic solvent such as dimethyl sulfoxide, if necessary.

[0053] The reaction between the polyol and the polyisocyanate compound can be carried out at room temperature. The atmosphere during the reaction between the polyol and the polyisocyanate compound may be air or an inert gas such as nitrogen gas or argon gas. The reaction time between the polyol and the polyisocyanate compound varies depending on the reaction temperature and the like and cannot be determined in general, so it is usually the time required for sufficient polyurethane production.

[0054] The method for producing polyurethane is not particularly limited, and a commonly used method can be used. Examples of methods for producing polyurethane include a method of mixing the polyol and the polyisocyanate compound to prepare polyurethane, but the present invention is not limited to such a method. When preparing polyurethane, additives such as a catalyst, a chain extender, water, a silicone-based antifoaming agent, and a silicon-containing inorganic powder may be added to the polyol and / or the polyisocyanate compound as needed.

[0055] By reacting the polyol with the polyisocyanate compound in the manner described above, polyurethane can be obtained.

[0056] (4) Properties and uses of polyurethane The number average molecular weight of the polyurethane is not particularly limited, but from the viewpoint of improving the heat resistance of the polyurethane and improving its decomposition property by ultraviolet light, it is preferably 3,000 to 100,000, and more preferably 5,000 to 50,000. The number average molecular weight of the polyurethane can be determined by gel permeation chromatography (GPC) as described in the following examples.

[0057] The polyurethane of the present invention is soluble in organic solvents such as dimethyl sulfoxide and hexafluoroisopropanol, and thus a spinning dope can be prepared by dissolving the polyurethane in an organic solvent. The amount of organic solvent relative to the polyurethane of the present invention cannot be determined in general because it varies depending on the type of organic solvent. Generally, it is preferable to add an organic solvent to the polyurethane so that the spinning dope has the desired viscosity. Polyurethane fibers can be produced by extruding the spinning dope obtained above through the pores of a spinneret and volatilizing and removing the organic solvent.

[0058] Furthermore, since the polyurethane of the present invention has thermoplastic properties, the polyurethane can be heated and melted, and then melt-spun using a melt spinning apparatus by injecting the melt-spinned polyurethane from fine holes in a spinneret to produce polyurethane fibers.

[0059] The spinneret is generally made of an alloy such as an alloy of gold and platinum, an alloy of platinum and iridium, or an alloy of platinum and palladium. The hole diameter of the spinneret is determined appropriately depending on the fineness of the target polyurethane fiber, but is usually about 0.05 to 0.1 mm. The number of holes provided in the spinneret is not particularly limited, but is usually about 1 to 20,000.

[0060] The polyurethane fiber may be a single fiber (filament), or may be a fiber formed by converging a plurality of single fibers extruded from a plurality of holes into a single bundle.

[0061] The polyurethane fibers obtained as described above may be subjected to further treatments such as washing, drying and crimping, if necessary.

[0062] The fineness of the polyurethane fiber obtained as described above varies depending on the application of the polyurethane fiber and cannot be determined in general terms. Therefore, it is preferable to determine the fineness appropriately depending on the application of the polyurethane fiber. An example of the fineness of the polyurethane fiber is 1 to 30 decitex, but the present invention is not limited to this fineness. The fineness of the polyurethane fiber can be easily adjusted by adjusting the hole diameter of the spinneret or the draw ratio when drawing the polyurethane fiber.

[0063] The polyurethane fibers may be used in the form of long fibers or may be cut to a desired length and used as short fibers. The fiber length of the polyurethane fibers varies depending on the application of the polyurethane fibers, and is therefore preferably determined appropriately depending on the application of the polyurethane fibers.

[0064] Polyurethane fibers can be used, for example, for woven fabrics, nonwoven fabrics, and knitted fabrics such as fishing nets.

[0065] The knitted fabric can be produced using the polyurethane fiber and a knitting machine or the like. When producing a knitted fabric, the polyurethane fiber may be used as is, or a blend of the polyurethane fiber with synthetic fibers such as polyester fibers and acrylic fibers, or fibers such as cotton yarn, wool yarn, or raw silk may be used. Examples of knitted fabrics include plain knitting, rib knitting, and purl knitting, but the present invention is not limited to these examples.

[0066] The woven fabric can be manufactured using a loom or the like, using polyurethane fibers for the warp, weft, or both the warp and weft. The woven fabric may be a blended fabric using blended yarns containing polyurethane fibers in some or all of the warp and weft, a union fabric in which the warp and weft have different compositions and polyurethane fibers are used in the warp and / or weft, or a highly woven fabric using warp and weft threads containing polyurethane fibers but with different fiber diameters. Examples of weaves that woven fabrics have include plain weave, twill weave, twill weave, satin weave, and modified weave, but the present invention is not limited to these examples.

[0067] Nonwoven fabrics can be produced by dry or wet processes using fibers containing polyurethane fibers. The fibers used in nonwoven fabrics may be polyurethane fibers alone, or may be blends of polyurethane fibers with synthetic fibers such as polyester fibers and acrylic fibers, or fibers such as cotton yarn, wool yarn, and raw silk. Dry processes include, for example, mechanical bonding methods such as the chemical pond process, thermal pond process, needle punching, and airlaid process, but the present invention is not limited to these examples. Wet processes include, for example, hydroentanglement, but the present invention is not limited to these examples.

[0068] Polyurethane fibers using the polyurethane of the present invention are decomposable by irradiation with ultraviolet light and have appropriate mechanical strength, and therefore can be suitably used in a variety of applications, including clothing such as gloves, underwear, socks, shirts, and suits, as well as face masks, materials for disposable diapers, and cosmetic sheets such as lotion wipes. The polyurethane of the present invention can also be used in applications similar to those of conventionally used ether-based polyurethanes, such as materials for artificial leather and cushioning materials.

[0069] Furthermore, since the polyurethane of the present invention is soluble in organic solvents, it can be used as an organic solvent solution, and since it has thermoplastic properties, it can be used as a molten material melted by heating. Therefore, it can be used for coating shells such as coated fertilizers and coated seeds for plants, and can also be used as a molding material for injection molding and the like.

[0070] The polyurethane of the present invention may contain additives in appropriate amounts depending on the intended use, as needed. Examples of additives include colorants such as pigments and dyes, UV absorbers, UV stabilizers, antioxidants, rust inhibitors, antibacterial agents, plasticizers, algae inhibitors, mildew inhibitors, flame retardants, and foaming agents, but the present invention is not limited to these examples. These additives may be used alone or in combination of two or more. The amount of additive varies depending on the type of additive, so it cannot be determined in general. Therefore, it is preferable to determine the amount appropriately depending on the type of additive.

[0071] As explained above, the polyurethane of the present invention is decomposable by irradiation with ultraviolet light, and is therefore expected to be used in a variety of applications as an environmentally friendly polymer. [Example]

[0072] Next, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

[0073] The physical properties of the compounds obtained in each example were examined according to the following methods. [Compound Identification] The compound was analyzed by nuclear magnetic resonance ( 1 The compounds were characterized by H-NMR, mass spectrometry (MS) and Fourier transform infrared spectroscopy (FT-IR).

[0074] (1) Nuclear magnetic resonance ( 1 H-NMR) Nuclear magnetic resonance ( 1H-NMR was measured using a nuclear magnetic resonance spectrometer (manufactured by Bruker, trade name: AVANCE 400, 400 MHz) by dissolving 5 mg of sample in 0.5 mL of dimethyl sulfoxide (manufactured by Kanto Chemical Co., Ltd., DMSO-d6), placing the resulting solution in a glass sample tube, and measuring at a temperature of 20°C with 16 accumulations.

[0075] (2) Molecular weight of the monomer Using a mass spectrometer (manufactured by Bruker, trade name: SolariX), a charge was applied to the monomer by electrospray ionization (ESI) and mass analysis was performed in positive and negative modes to measure the molecular weight of the monomer.

[0076] (3) Average molecular weight of polyurethane The average molecular weights (weight average molecular weight and number average molecular weight) of the polyurethanes were measured by gel permeation chromatography (GPC). More specifically, the GPC measurement apparatus was equipped with a liquid pump unit (JASCO Corporation, product number: PU-2080), a column oven (GL Sciences Corporation, product number: CO631A, set temperature: 40°C), an ultraviolet-visible detector (JASCO Corporation, product number: UV-2075), a differential refractometer (JASCO Corporation, product number: RI-2031), and two columns (Showa Denko K.K., product name: Shodex GPC LF-604 (inner diameter: 6.0 mm, length: 150 mm)). Polymethyl methacrylate standards [molecular weight (Mp): 3070, 7360, 18500, 68800, 211000, 569000, or 1050000] were used as standard samples, hexafluoroisopropanol containing 5 mM sodium trifluoroacetate was used as the mobile phase, and the solution flow rate was 0.3 mL / min.

[0077] (4) Fourier transform infrared spectroscopy (FT-IR) Fourier transform infrared spectroscopy (FT-IR) was performed using a Fourier transform infrared spectrometer (Perkin Elmer, product name: Spectrum 100 FT-IR Spectrometer) in the measurement wavenumber range of 400 to 4000 cm -1 The measurement was performed using the ATR method with four accumulations.

[0078] [Properties of polyurethane] The properties of the polyurethane were investigated by thermogravimetric analysis (TGA) and UV irradiation.

[0079] (1) Thermogravimetric analysis (TGA) Thermogravimetric analysis of polyurethane was performed using a thermogravimetric differential thermal analyzer (Hitachi High-Tech Science Corporation, Model No. STA7200) with a sample weight of 4 to 8 mg. The sample was heated in a nitrogen gas atmosphere (nitrogen gas flow rate: 250 mL / min) at a heating rate of 10°C / min in the temperature range from 20°C to 800°C using a platinum pan as a reference blank (no sample). The decomposition onset temperature (T do The temperatures at which the sample mass decreased by 5% and 10% were measured as the 5% weight loss temperatures (T d5 ) or 10% weight loss temperature (T d10 ) was decided.

[0080] (2) UV irradiation Using an ultraviolet irradiation device (LUMEN DYNAMICS, product number: Omni Cure SERIES 1000), ultraviolet light with a wavelength of 400 nm or less was irradiated at an intensity of 80 mW / cm. 2 The properties of polyurethane were investigated when it was irradiated with .

[0081] The reagents used in the following examples are as follows: Methanol (MeOH): Kanto Chemical Co., Ltd., Grade 1, Purity: 99.5% Ethyl acetate: Kanto Chemical Co., Ltd., Grade 1, purity: 99.3% Dimethyl sulfoxide (DMSO): Kanto Chemical Co., Ltd., special grade, purity: 98.0% Itaconic acid: Iwata Chemical Industry Co., Ltd., purity: 99.7% 1,10-Diaminodecane: Tokyo Chemical Industry Co., Ltd., purity: 98.0% 3-Amino-1-propanol: Tokyo Chemical Industry Co., Ltd., purity: 99.0% 1,6-Hexamethylene diisocyanate (HDI): Tokyo Chemical Industry Co., Ltd., purity: 98.0% Dicyclohexylmethane-4,4'-diisocyanate (CDI): Tokyo Chemical Industry Co., Ltd., purity: 90.0% Methylenediphenyl-4,4'-diisocyanate (MDI): Tokyo Chemical Industry Co., Ltd., purity: 97.0% m-Xylylene diisocyanate (XDI): Tokyo Chemical Industry Co., Ltd., purity: 98.0%

[0082] Example 1 (Preparation of Carboxypyrrolidone Compound) Carboxypyrrolidone compounds were prepared based on the following reaction pathway.

[0083] [ka]

[0084] More specifically, the carboxypyrrolidone compound was obtained by the following procedure. 3.24 g (24.9 mmol) of itaconic acid and 2.06 g (27.5 mmol) of 3-amino-1-propanol were mixed in the air at room temperature, and 25 mL of methanol was added to the resulting mixture, which was then heated at 110°C for 18 hours with stirring to obtain a reaction solution containing a carboxypyrrolidone compound.

[0085] The reaction solution obtained above was added to methanol at room temperature in the air to dissolve the carboxypyrrolidone compound contained in the reaction solution, and the resulting mixed solution was added dropwise to ethyl acetate, and the precipitated pale yellow oily substance was collected. The oily substance obtained above was dried under reduced pressure to obtain 4.26 g of 1-(3-hydroxypropyl)-5-oxopyrrolidine-3-carboxylic acid as the carboxypyrrolidone compound (yield: 90.8%). The 1-(3-hydroxypropyl)-5-oxopyrrolidine-3-carboxylic acid obtained above has the formula:

[0086] [ka]

[0087] It was a compound represented by the formula:

[0088] The 1-(3-hydroxypropyl)-5-oxopyrrolidine-3-carboxylic acid obtained above 1 The results of H-NMR and mass spectrometry are as follows: 1 The H-NMR spectrum is shown in Figure 1, and the ESI-MS spectrum is shown in Figure 2.

[0089] 1 H-NMR (400MHz, DMSO-d6): δ1.58 (m, 2H, J=6.8, CH), 1.79 (m, 2H, J=6.5, CH), 2.50 (m, 4H, J=6.7, CH), 3.22 (m, 1H,J=7.0, CH), 3.30 (t, 2H, J=6.3, CH), 3.49 (m, 2H, J=5.5, CH), 3.56 (m, 2H, J=8.9, CH), 4.01 (t, 1H, J=6.3, CH). Mass spectrometry (ESI-MS): C8H 13 NO4, theoretical value 186.079673; measured value 186.077181.

[0090] 1-(3-hydroxypropyl)-5-oxopyrrolidine-3-carboxylic acid shown in FIG.1 In the H-NMR spectrum, no peaks attributable to the vinylene group (CH=CH) of itaconic acid were observed around 5-6 ppm, but peaks attributable to the pyrrolidone ring were observed at 2.50 ppm, 3.22 ppm, and 3.56 ppm, confirming that the reaction between itaconic acid and 3-amino-1-propanol had proceeded sufficiently.

[0091] 2, a peak corresponding to the theoretical molecular mass of 1-(3-hydroxypropyl)-5-oxopyrrolidine-3-carboxylic acid, 187.0845, was clearly observed in the ESI-MS spectrum, confirming that 1-(3-hydroxypropyl)-5-oxopyrrolidine-3-carboxylic acid was obtained.

[0092] Example 2 (Preparation of Polyol) The polyol was prepared based on the following reaction pathway:

[0093] [ka]

[0094] More specifically, the polyol was obtained by the following procedure. At room temperature in the atmosphere, 4.26 g (22.8 mmol) of the 1-(3-hydroxypropyl)-5-oxopyrrolidine-3-carboxylic acid obtained above was mixed with 1.31 g (7.59 mmol) of diaminodecane, and the resulting mixture was heated at 140°C for 2 hours with stirring to obtain a reaction solution containing a polyol.

[0095] The reaction solution obtained above was added to methanol at room temperature in the air to dissolve the polyol, and the resulting mixed solution was added dropwise to ethyl acetate to precipitate a pale yellow oily substance, which was then recovered. The oily solid obtained above was dried under reduced pressure to obtain 3.29 g of N,N'-(decane-1,10-diyl)bis(1-(3-hydroxypropyl)-5-oxopyrrolidine-3-carboxamide) as a polyol (yield: 84.9%). The N,N'-(decane-1,10-diyl)bis(1-(3-hydroxypropyl)-5-oxopyrrolidine-3-carboxamide) obtained above has the formula:

[0096] [ka]

[0097] It was a compound represented by the formula:

[0098] The N,N'-(decane-1,10-diyl)bis(1-(3-hydroxypropyl)-5-oxopyrrolidine-3-carboxamide) obtained above 1 The results of H-NMR and mass spectrometry are as follows: 1 The H-NMR spectrum is shown in FIG. 3, and the ESI-MS spectrum is shown in FIG.

[0099] 1 H-NMR (400MHz, DMSO-d6) δ1.25 (m, 12H, J=3.72, CH), 1.39 (m, 4H, J=6.2, CH), 1.57 (m, 4H, J=6.72, CH), 2.37 (m, 4H,J=8.52, CH), 2.76 (t, 4H, J=7.40, CH), 3.04 (m, 2H, J=5.48, CH), 3.17 (m, 4H, J=5.04, CH), 3.37 (m, 4H, J=5.36, CH), 3.49 (m, 4H, J=7.28, CH), 4.44 (m, 2H, J=2.68, NH), 8.02 (m, 2H, J=5.84, OH). Mass spectrometry (ESI-MS): C 26 H 46 N4O6, theoretical value 511.34516; measured value 511.349012.

[0100] As shown in Figure 3 1 In the H-NMR spectrum, a peak b derived from an alcohol was observed at around 5 ppm, and a peak a derived from an amide bond was observed at around 8 ppm.

[0101] Furthermore, in the ESI-MS spectrum shown in Figure 4, a peak corresponding to the theoretical molecular mass of 510.3417 for N,N'-(decane-1,10-diyl)bis(1-(3-hydroxypropyl)-5-oxopyrrolidine-3-carboxamide) was confirmed. This confirmed that N,N'-(decane-1,10-diyl)bis(1-(3-hydroxypropyl)-5-oxopyrrolidine-3-carboxamide) was obtained.

[0102] Example 3 (Preparation of Polyurethane A) Polyurethane A (HDI-PU) was prepared based on the following reaction pathway.

[0103] [ka]

[0104] More specifically, polyurethane A was obtained by the following procedure. At room temperature in the atmosphere, 2.11 g (4.13 mmol) of the N,N'-(decane-1,10-diyl)bis(1-(3-hydroxypropyl)-5-oxopyrrolidine-3-carboxyamide) obtained above was added to 2.0 mL of dimethyl sulfoxide (DMSO) and dissolved to prepare a diol solution.

[0105] Furthermore, 0.69 g (4.13 mmol) of 1,6-hexamethylene diisocyanate (HDI) was added to 2.0 mL of dimethyl sulfoxide (DMSO) at room temperature in the air and dissolved therein to obtain a diisocyanate solution.

[0106] At room temperature in the atmosphere, while stirring the diisocyanate solution obtained above, the diol solution obtained above was slowly added dropwise to the diisocyanate solution obtained above, and 1,6-hexamethylene diisocyanate and N,N'-(decane-1,10-diyl)bis(1-(3-hydroxypropyl)-5-oxopyrrolidine-3-carboxyamide) were polymerized for 18 hours, thereby obtaining a reaction solution containing polyurethane A.

[0107] The reaction solution obtained above was added dropwise to 200 mL of methanol while stirring the methanol at room temperature in the air, and the precipitated pale yellow fibrous solid was collected. The obtained solid was dried under reduced pressure to obtain a compound of the formula:

[0108] [ka]

[0109] Thus, 1.08 g of polyurethane A having a repeating unit represented by the formula: was obtained (yield: 38.6%).

[0110] Polyurethane A was dissolved in hexafluoroisopropanol (HFIP) containing 5 mM sodium trifluoroacetate, and the number-average molecular weight and weight-average molecular weight of the resulting solution were measured by gel permeation chromatography (GPC). The number-average molecular weight of Polyurethane A was found to be 25,000, and the weight-average molecular weight was found to be 50,000.

[0111] Example 4 (Preparation of Polyurethane B) Polyurethane B (CDI-PU) was prepared based on the following reaction pathway.

[0112] [ka]

[0113] More specifically, polyurethane B was obtained by the following procedure. At room temperature in the air, 5.05 g (9.90 mmol) of N,N'-(decane-1,10-diyl)bis(1-(3-hydroxypropyl)-5-oxopyrrolidine-3-carboxamide) prepared as a polyol in the same manner as above was added to 2.0 mL of dimethyl sulfoxide (DMSO) and dissolved therein to prepare a diol solution.

[0114] Furthermore, 2.60 g (9.90 mmol) of dicyclohexylmethane-4,4′-diisocyanate (CDI) was added to 2.0 mL of dimethyl sulfoxide (DMSO) at room temperature in the air and dissolved therein to obtain a diisocyanate solution.

[0115] At room temperature in the atmosphere, while stirring the diisocyanate solution obtained above, the diol solution obtained above was slowly added dropwise to the diisocyanate solution obtained above, and dicyclohexylmethane-4,4'-diisocyanate and N,N'-(decane-1,10-diyl)bis(1-(3-hydroxypropyl)-5-oxopyrrolidine-3-carboxamide) were polymerized for 1 hour, thereby obtaining a reaction solution containing polyurethane B.

[0116] The reaction solution obtained above was added dropwise to 200 mL of methanol while stirring the methanol at room temperature in the air, and the precipitated pale yellow fibrous solid was collected. The obtained solid was dried under reduced pressure to obtain a compound of the formula:

[0117] [ka]

[0118] Thus, 1.21 g of polyurethane B having a repeating unit represented by the formula: was obtained (yield: 15.8%).

[0119] Polyurethane B was dissolved in hexafluoroisopropanol (HFIP) containing 5 mM sodium trifluoroacetate, and the resulting solution was used to measure the number-average molecular weight and weight-average molecular weight of Polyurethane B. The number-average molecular weight of Polyurethane B was 30,000, and the weight-average molecular weight was 70,000.

[0120] Example 5 (Preparation of Polyurethane C) Polyurethane C (MDI-PU) was prepared based on the following reaction pathway.

[0121] [ka]

[0122] More specifically, polyurethane C was obtained by the following procedure. At room temperature in the air, 2.10 g (4.11 mmol) of N,N'-(decane-1,10-diyl)bis(1-(3-hydroxypropyl)-5-oxopyrrolidine-3-carboxyamide) prepared as a polyol in the same manner as above was added to 1.0 mL of dimethyl sulfoxide (DMSO) and dissolved therein to prepare a diol solution.

[0123] Furthermore, 1.03 g (4.11 mmol) of methylenediphenyl-4,4′-diisocyanate (MDI) was added to 1.0 mL of dimethyl sulfoxide (DMSO) at room temperature in the air and dissolved therein to obtain a diisocyanate solution.

[0124] At room temperature in the atmosphere, while stirring the diisocyanate solution obtained above, the diol solution obtained above was slowly added dropwise to the diisocyanate solution obtained above, and methylenediphenyl-4,4'-diisocyanate and N,N'-(decane-1,10-diyl)bis(1-(3-hydroxypropyl)-5-oxopyrrolidine-3-carboxamide) were polymerized for 1 hour, thereby obtaining a reaction solution containing polyurethane C.

[0125] The reaction solution obtained above was added dropwise to 200 mL of methanol while stirring the methanol at room temperature in the air, and the precipitated pale yellow fibrous solid was collected. The obtained solid was dried under reduced pressure to obtain a compound of the formula:

[0126] [ka]

[0127] Thus, 0.94 g of polyurethane C having a repeating unit represented by the following formula was obtained (yield: 30.0%).

[0128] Polyurethane C was dissolved in hexafluoroisopropanol (HFIP) containing 5 mM sodium trifluoroacetate, and the number-average molecular weight and weight-average molecular weight of the resulting solution were measured by gel permeation chromatography (GPC). The number-average molecular weight of Polyurethane C was 5,000, and the weight-average molecular weight was 20,000.

[0129] Example 6 (Preparation of Polyurethane D) Polyurethane D (XDI-PU) was prepared based on the following reaction pathway.

[0130] [ka]

[0131] More specifically, polyurethane D was obtained by the following procedure. At room temperature in the air, 0.93 g (2.75 mmol) of N,N'-(decane-1,10-diyl)bis(1-(3-hydroxypropyl)-5-oxopyrrolidine-3-carboxamide) prepared as a polyol in the same manner as above was added to 2.0 mL of dimethyl sulfoxide (DMSO) and dissolved therein to prepare a diol solution.

[0132] Furthermore, 0.52 g (2.75 mmol) of m-xylylene diisocyanate (XDI) was added to 2.0 mL of dimethyl sulfoxide (DMSO) at room temperature in the air and dissolved therein to obtain a diisocyanate solution.

[0133] At room temperature in the atmosphere, while stirring the diisocyanate solution obtained above, the diol solution obtained above was slowly added dropwise to the diisocyanate solution obtained above, and m-xylylene diisocyanate and N,N'-(decane-1,10-diyl)bis(1-(3-hydroxypropyl)-5-oxopyrrolidine-3-carboxyamide) were polymerized for 5 hours, thereby obtaining a reaction solution containing polyurethane D.

[0134] The reaction solution obtained above was added dropwise to 200 mL of methanol while stirring the methanol at room temperature in the air, and the precipitated pale yellow fibrous solid was collected. The obtained solid was dried under reduced pressure to obtain a compound of the formula:

[0135] [ka]

[0136] Thus, 0.22 g of polyurethane D having a repeating unit represented by the formula: was obtained (yield: 15.2%).

[0137] Polyurethane D was dissolved in hexafluoroisopropanol (HFIP) containing 5 mM sodium trifluoroacetate, and the number-average molecular weight and weight-average molecular weight of the resulting solution were measured by gel permeation chromatography (GPC). The number-average molecular weight of Polyurethane D was found to be 50,000, and the weight-average molecular weight was found to be 100,000.

[0138] The polyurethanes A to D obtained above 1 The H-NMR spectrum (400 MHz, DMSO-d6) is shown in Figure 5, and the IR spectrum is shown in Figure 6.

[0139] In the figure, HDI-PU, CDI-PU, MDI-PU and XDI-PU represent polyurethanes A to D, respectively.

[0140] As shown in Figure 5 1 In the H-NMR spectrum, a peak derived from a urethane bond was confirmed to exist around 6 ppm.

[0141] In addition, in the IR spectrum shown in FIG. -1 The absorption due to CO stretching vibration is observed around 1250cm. -1 Absorption due to CN stretching vibration near 1620cm -1 Absorption due to NH vibration, 1560cm -1 Absorption due to C=O stretching vibration near 3450cm -1 Absorption due to NH stretching vibration was confirmed around this region. These findings indicate that urethane bonds are formed in polyurethanes A to D.

[0142] [Thermal properties of polyurethane] The thermal properties of polyurethanes A to D were investigated by thermogravimetric analysis (TGA), and the 5% weight loss temperature (T d5 ) and 10% weight loss temperature (T d10 The results are shown in Table 1. Ta.

[0143] [Table 1]

[0144] From the results shown in Table 1, it can be seen that polyurethanes A to D have good heat resistance, since their 5% weight loss temperatures are 260°C or higher and their 10% weight loss temperatures are 280°C or higher. Furthermore, among polyurethanes A to D, polyurethane A has a 10% weight loss temperature (T d10) is the highest, which indicates that it has the best heat resistance. Furthermore, when thermogravimetric analysis was performed on polyurethanes A to D, a two-stage thermal decomposition was confirmed, which suggests that the urethane bond, which has a weak bonding strength, was thermally decomposed, followed by the thermal decomposition of bonds such as amide bonds, CC bonds, CH bonds, and C=C bonds.

[0145] [Polyurethane Solubility] The solubility of polyurethanes A to D in various solvents was investigated. More specifically, 2 mg of each polyurethane was used, and each polyurethane was added to 1 mL of various organic solvents or 1 mL of water. The mixture was allowed to stand at room temperature (approximately 20°C) under atmospheric pressure, and the solution was visually inspected for its dissolution in the solvent. If the polyurethane did not dissolve in the solvent one hour after the start of polyurethane addition, the solvent was heated to 60°C to check for its dissolution. The results are shown in Table 2.

[0146] The meanings of the abbreviations in Table 2 are as follows: NMP: N-methylpyrrolidone DMF: N,N-dimethylformamide DMAc: N,N-dimethylacetamide DMSO: Dimethyl sulfoxide THF: Tetrahydrofuran HFIP: Hexafluoroisopropanol

[0147] The solubility evaluations shown in Table 2 are as follows:

[0148] [Evaluation criteria] +:dissolution Dissolved by heating to ±60°C -: Insoluble

[0149] [Table 2]

[0150] The results shown in Table 2 show that all of the polyurethanes A to D are soluble in HFIP, but are insoluble in THF, acetone, dichloromethane, water, methanol, and acetic acid.

[0151] Therefore, it is possible to select an organic solvent that can dissolve the polyurethane depending on the type of polyurethane, and cast the solution obtained by dissolving the polyurethane in the organic solvent to form a film, or to use the solution as a molding material. Furthermore, these polyurethanes are solvent-resistant to THF, acetone, dichloromethane, water, methanol, and acetic acid, making them suitable for applications requiring solvent resistance to these solvents.

[0152] [Decomposition of polyurethane by ultraviolet irradiation] Polyurethane A was immersed in water at 20°C and exposed to ultraviolet light with a wavelength of 250 to 400 nm at an intensity of 80 mW / cm. 2 The polyurethane A was irradiated with UV light for 12 hours. The appearance of the polyurethane A was visually inspected 2, 4, 6, and 12 hours after the start of UV irradiation. A control sample was immersed in water at 20°C for 12 hours without UV irradiation. The results are shown in Figure 7. Figure 7 is a photograph showing the change over time of polyurethane A when irradiated with UV light. In Figure 7, "0 h" indicates polyurethane A immersed in water at 20°C for 12 hours without UV irradiation, and "2 h," "4 h," "6 h," and "12 h" indicate polyurethane A 2, 4, 6, and 12 hours after the start of UV irradiation, respectively.

[0153] The results shown in Figure 7 show that polyurethane A becomes brittle and begins to crumble when immersed in water and exposed to ultraviolet light. Furthermore, when a part of polyurethane A was touched with a finger two hours after ultraviolet light exposure, it was confirmed that polyurethane A was brittle, and when a part of polyurethane A was touched with a finger 12 hours after ultraviolet light exposure, it was confirmed that polyurethane A crumbled with just a little force.

[0154] Furthermore, polyurethane A was immersed in water at 20°C and irradiated with ultraviolet light, and the mass loss rate of polyurethane A was measured after 12 hours. As a result, the mass loss rate of polyurethane A after 12 hours without ultraviolet light irradiation was approximately 8.7% by mass, whereas the mass loss rate of polyurethane A after 12 hours of ultraviolet light irradiation was approximately 20.5% by mass. This indicates that polyurethane is easily dissolved into water by ultraviolet light irradiation.

[0155] Next, polyurethane A was immersed in water at 20°C and irradiated with ultraviolet light for 12 hours. After that, polyurethane A was filtered, and the resulting filtrate was 1 The 1H-NMR of the filtrate was examined. 1 A peak thought to be due to NH was observed around 7 ppm in the H-NMR spectrum, and a peak thought to be due to COOH was observed around 12.5 ppm. From this, it is thought that the pyrrolidone ring in polyurethane A opens upon irradiation with ultraviolet light, generating a carboxyl group and a secondary amine, which causes polyurethane A to become water-soluble.

[0156] In contrast, polyurethane A was immersed in water at 20°C for 12 hours without UV irradiation, and then the polyurethane A was filtered. 1 When H-NMR was examined, none of the above-mentioned peaks were observed. Therefore, it is considered that, when ultraviolet light was not irradiated, the pyrrolidone ring did not open, and therefore, polyurethane A did not become water-soluble.

[0157] From the above results, it is clear that polyurethane A decomposes in water when irradiated with ultraviolet light and dissolves in water.

[0158] [Degradability of polyurethane under acidic conditions] 5 mL of 0.1 M hydrochloric acid was added to 10 mg of polyurethane A, and the resulting mixture was stirred at room temperature for 24 hours. However, polyurethane A did not completely dissolve in the hydrochloric acid. Therefore, the mixture was heated at 60°C for 3 hours under stirring, and then filtered at the same temperature. 1 The H-NMR spectrum was examined. 1 In the H-NMR spectrum, a peak due to NH was observed around 7 ppm and a peak due to COOH was observed around 12.5 ppm.

[0159] This shows that polyurethane A dissolves under acidic conditions, just as when polyurethane A is irradiated with ultraviolet light, and therefore polyurethane A has the property of dissolving in water under acidic conditions. [Industrial Applicability]

[0160] The polyurethane of the present invention is decomposable in water when irradiated with ultraviolet light, and decomposes when released into the ocean and under acidic conditions. Therefore, it is expected to be used as a coating material for, for example, fibers, clothing such as gloves, underwear, socks, shirts, and suits, face masks, materials for disposable diapers, wipes for lotion, materials for artificial leather, cushioning materials, coated fertilizers for plants, coated seeds, and the like.

Claims

1. A polyurethane obtained by polymerizing a polyol and a polyisocyanate compound, wherein the polyol is represented by formula (I): 【Chemical 1】 (In the formula, R 1 and R 2 each independently represents an alkylene group which may have a substituent. A polyurethane characterized in that the polyol is represented by the following formula:

2. A method for producing polyurethane by polymerizing a polyol and a polyisocyanate compound, wherein the polyol is a compound represented by formula (I): 【Chemistry 2】 (In the formula, R 1 and R 2 each independently represents an alkylene group which may have a substituent. and polymerizing the polyol with a polyisocyanate compound.

Images