Urethane prepolymer, polyurethane foam, and bat

Abstract

To improve the impact resilience of a polyurethane foam by using biomass-derived raw materials.SOLUTION: The present invention provides a urethane prepolymer with terminal isocyanate groups, which is a reaction product of polyols and polyisocyanates. The polyols include at least polytetramethylene glycol and castor oil polyol. The polyisocyanates include 1,5-naphthalene diisocyanate.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to urethane prepolymers, polyurethane foams, and batts. [Background technology]

[0002] Patent Document 1 discloses a two-component curable polyurethane foam resin composition containing a curing agent and a base agent containing an isocyanate-terminated urethane prepolymer. The isocyanate-terminated urethane prepolymer described is a urethane prepolymer using MDI, castor oil polyol, and polytetramethylene glycol. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2011 / 132490 Summary of the Invention [Problem to be solved by the invention]

[0004] From the perspective of SDGs (Sustainable Development Goals) and carbon neutrality, there is a demand for technology that uses biomass-derived raw materials and can reduce the impact on the global carbon concentration even when the material is disposed of. Furthermore, there is a demand for technology that can improve the impact resilience of polyurethane foam even when biomass-derived raw materials are used.

[0005] The present disclosure has been made in view of the above circumstances, and has an object to provide a technique capable of improving the impact resilience of a polyurethane foam by using a biomass-derived raw material. The present disclosure can be realized in the following aspects. [Means for solving the problem]

[0006] [1] A urethane prepolymer having an isocyanate group at its end, which is a reaction product of a polyol and a polyisocyanate, The polyol includes at least polytetramethylene glycol and castor oil polyol, The polyisocyanate includes 1,5-naphthalene diisocyanate. [2] A polyurethane foam obtained from a composition for polyurethane foam comprising the urethane prepolymer according to [1]. [3] A polyurethane foam obtained from a polyurethane foam composition comprising polytetramethylene glycol, castor oil polyol, and 1,5-naphthalene diisocyanate. [4] A bat comprising the polyurethane foam according to [2] or [3]. Effect of the Invention

[0007] According to the present disclosure, the impact resilience of a polyurethane foam can be improved by using a raw material derived from biomass. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The present disclosure will be described in detail below. In this specification, when a numerical range is described using "-", the lower limit and the upper limit are included unless otherwise specified. For example, the description "10-20" includes both the lower limit "10" and the upper limit "20". In other words, "10-20" has the same meaning as "10 or more and 20 or less". In this specification, the upper limit and the lower limit of each numerical range can be arbitrarily combined.

[0009] 1. Urethane prepolymer The urethane prepolymer is a urethane prepolymer having an isocyanate group at the end, which is a reaction product of a polyol and a polyisocyanate. The polyol includes at least polytetramethylene glycol and castor oil polyol. The polyisocyanate includes 1,5-naphthalene diisocyanate.

[0010] (1) Polyol (1.1) Polytetramethylene glycol The polyol includes polytetramethylene glycol, which is a polyol having a repeating unit represented by [-CH2CH2CH2CH2-O-].

[0011] The weight average molecular weight and hydroxyl value of polytetramethylene glycol are not particularly limited. The weight average molecular weight of polytetramethylene glycol is preferably 500-5000, more preferably 1000-4500, and even more preferably 1300-4000. The hydroxyl value of polytetramethylene glycol is preferably 20 mgKOH / g or more and 200 mgKOH / g or less, more preferably 25 mgKOH / g or more and 150 mgKOH / g or less, and even more preferably 30 mgKOH / g or more and 120 mgKOH / g or less. In the present disclosure, the weight average molecular weight of the polyol is a value measured by gel permeation chromatography (GPC). When the polyol is a commercially available product, the catalog value may be used as the weight average molecular weight.

[0012] From the viewpoint of improving the impact resilience of the polyurethane foam, the content of polytetramethylene glycol etc. is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, and even more preferably 65 parts by mass or more, based on 100 parts by mass of the entire polyol. The content of polytetramethylene glycol etc. is, for example, 98 parts by mass or less.

[0013] (1.2) Castor oil polyols Castor oil is a vegetable oil obtained from the seeds of the castor bean plant, which belongs to the Euphorbiaceae family. Castor oil is an ester of fatty acids and glycerin. The main component of castor oil fatty acids is ricinoleic acid. Ricinoleic acid usually accounts for 80% or more by mass of all fatty acids. Other components of castor oil fatty acids include unsaturated fatty acids such as oleic acid, linoleic acid, and linolenic acid, and saturated fatty acids such as palmitic acid and stearic acid.

[0014] Castor oil polyol is usually a polyol produced using castor oil, castor oil fatty acid, hydrogenated castor oil obtained by hydrogenating castor oil, or hydrogenated castor oil fatty acid obtained by hydrogenating castor oil fatty acid. Such castor oil polyol may be one or more selected from the group consisting of castor oil, a reaction product of castor oil and polyhydric alcohol, an esterification reaction product of castor oil fatty acid and polyhydric alcohol, hydrogenated castor oil, a reaction product of hydrogenated castor oil and polyhydric alcohol, and an esterification reaction product of hydrogenated castor oil fatty acid and polyhydric alcohol. Examples of polyhydric alcohols for obtaining the esterification reaction product include ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,6-hexanediol, neopentyl glycol, trimethylolpropane, ditrimethylolpropane, trimethylolethane, glycerin, diglycerin, pentaerythritol, dipentaerythritol, polyester polyol, polycaprolactone polyol, polytetramethylene glycol polyol, polybutadiene polyol, polycarbonate polyol, and acrylic polyol. The castor oil polyol may be one or more of the above compounds.

[0015] Specific examples of castor oil polyols include URIC H-30, URIC H-31, URIC H-52, URIC H-57, URIC H-62, URIC H-73X, URIC H-81, URIC H-102, URIC H-420, URIC H-854, URIC H-870, URIC H-1823, URIC H-1824, URIC H-1830, POLYCASTOR #10, POLYCASTOR #30, URIC Y-403, URIC Y-406, URIC AC-005, URIC AC-006, URIC AC-009, URIC H-368, URIC PH-319, URIC PH-5001, and URIC HF-2009 manufactured by Ito Oil Mills, Ltd., and TLM, LM-R, ELA-DR, HS CM, and HS Examples of such materials include HS 2G-120, HS 2G-160R, HS 2G-270B, HS KA-001, HS CM-025P, HS CM-075P, and HS 3G-500B.

[0016] The average number of functional groups of castor oil polyol is not particularly limited. The average number of functional groups of castor oil polyol is preferably 1.5-3.5, more preferably 1.8-3.0, and even more preferably 2.0-2.5. The above-mentioned "functional group" refers to a hydroxyl group. The average number of functional groups refers to the number of functional groups per molecule, and can be, for example, the value listed in the catalog of the manufacturer of castor oil polyol.

[0017] The hydroxyl value (OHV) of the castor oil polyol is not particularly limited. The hydroxyl value of the castor oil polyol is preferably from 50 mgKOH / g to 300 mgKOH / g, more preferably from 55 mgKOH / g to 200 mgKOH / g, and even more preferably from 60 mgKOH / g to 160 mgKOH / g.

[0018] (1.3) Mass ratio of polytetramethylene glycol to castor oil polyol The mass ratio of polytetramethylene glycol to castor oil polyol is not particularly limited. The mass ratio of polytetramethylene glycol to castor oil polyol [polytetramethylene glycol:castor oil polyol] is preferably 70:30-98:2, more preferably 80:20-95:5, and even more preferably 85:15-95:5.

[0019] The polyol may contain polyols (other polyols) other than polytetramethylene glycol and castor oil polyol. Even in this case, the content of the other polyols is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, based on 100 parts by mass of the total polyols.

[0020] As the polytetramethylene glycol, it is preferable to use polytetramethylene glycol derived from biomass (e.g., derived from plants) from the viewpoint of consideration for the environment in the carbon neutral concept. As the castor oil polyol, it is preferable to use castor oil polyol derived from biomass (e.g., derived from plants) from the viewpoint of consideration for the environment in the carbon neutral concept. Since there is no difference in physical properties such as molecular weight, mechanical properties, and thermal properties between biomass-derived polyol and fossil fuel-derived polyol, the biomass plastic degree specified in ASTM D6866 is generally used to distinguish between them. When biomass-derived polytetramethylene glycol and / or castor oil polyol is used, the biomass plastic content of the polyurethane foam is not particularly limited. The biomass plastic content of the polyurethane foam is preferably 40% or more, more preferably 50% or more, and even more preferably 60% or more. The upper limit is not particularly limited, and is usually less than 100%.

[0021] (2) Polyisocyanate From the viewpoint of improving the impact resilience of the polyurethane foam, the polyisocyanate contains 1,5-naphthalene diisocyanate, and preferably contains only 1,5-naphthalene diisocyanate.

[0022] (3) Method for producing urethane prepolymer The urethane prepolymer can be produced by mixing the polyisocyanate so that the isocyanate group of the polyisocyanate is in excess of the hydroxyl group of the polyol. Specifically, a predetermined amount of polytetramethylene glycol and castor oil polyol are charged into a tank or the like, heated to a predetermined temperature (e.g., 130°C), and while maintaining the heated temperature and filling the tank with nitrogen, a predetermined amount of polyisocyanate is charged and reacted while stirring, to obtain a urethane prepolymer having an isocyanate group at its end.

[0023] When producing the urethane prepolymer, the equivalent ratio of the isocyanate groups in the isocyanate to the hydroxyl groups in the polyol, expressed as [NCO] / [OH], is preferably 1.01 / 1-10 / 1, more preferably 1.2 / 1-9 / 1, and even more preferably 1.5 / 1-7.5 / 1.

[0024] The isocyanate group content (hereinafter also referred to as "NCO %) of the urethane prepolymer is preferably 2.5% or more and 5.0% or less, more preferably 3.0% or more and 5.0% or less, from the viewpoints of mechanical strength, flexibility, and durability.

[0025] (4) Effects of urethane prepolymer According to the urethane prepolymer of the present embodiment, the impact resilience of the polyurethane foam can be improved by using the biomass-derived castor oil polyol. The reason is not clear, but is presumed as follows. Note that the present disclosure is not limited to this presumed reason.

[0026] The structure derived from polytetramethylene glycol and 1,5-naphthalene diisocyanate is believed to contribute to improving the crystallinity of polyurethane. When the crystallinity of polyurethane is increased, the resilience modulus of polyurethane foam can be improved. Furthermore, when castor oil polyol is used in combination, an alkyl chain (chain-like hydrocarbon structure) derived from castor oil polyol can be arranged in the straight chain of the urethane prepolymer. The presence of an alkyl chain derived from castor oil polyol in the straight chain of the urethane prepolymer gives flexibility to the polyurethane, and it is presumed that the resilience modulus can be improved compared to the case where only polytetramethylene glycol is used as the polyol. In addition, according to the prepolymer method using the urethane prepolymer, it is easy to adjust the distribution of the structures derived from each component of polytetramethylene glycol, castor oil polyol, and 1,5-naphthalene diisocyanate in the polyurethane. As a result, it is presumed that the resilience of the polyurethane foam can be suitably improved.

[0027] 2. Polyurethane foam (part 1) The polyurethane foam (1) is obtained from the polyurethane foam composition (A) containing the above-mentioned urethane prepolymer. In the polyurethane foam composition (A), the explanation in the section "1. Urethane prepolymer" is applied as it is, and the explanation is omitted.

[0028] (1) Composition for polyurethane foam (A) The polyurethane foam composition (A) is a composition used in the prepolymer method. The polyurethane foam composition (A) contains, for example, a urethane prepolymer and a compound having an active hydrogen group. The polyurethane foam composition (A) may contain a catalyst.

[0029] The compound having an active hydrogen group is preferably a compound having a number average molecular weight of 18-1000. Examples of the compound having an active hydrogen group include water, polyethylene glycol, polypropylene glycol, polyester polyol, castor oil, etc. Among these, water is preferred. When the compound having an active hydrogen group is water, it reacts with the urethane prepolymer to generate carbon dioxide gas, and the carbon dioxide gas causes foaming. When the compound having an active hydrogen group is water, it is more preferred to use it in combination with an emulsifier. Examples of the emulsifier include nonionic emulsifiers such as polyoxyethylene nonylphenyl ether and polyethylene glycol ester, anionic emulsifiers such as sodium salt of castor oil, sodium salt of sulfonated castor oil, and alkylbenzene sulfonate salt, and cationic emulsifiers such as alkylamine salt and alkyltrimethylammonium salt, and may be used alone or in combination of two or more kinds. The amount of water is preferably 0.3 to 5 parts by mass based on 100 parts by mass of the urethane prepolymer having an isocyanate group, and the amount of emulsifier is preferably 0.01 to 10 parts by mass based on 100 parts by mass of the urethane prepolymer having an isocyanate group.

[0030] The catalyst contained in the polyurethane foam composition (A) may be a known urethanization catalyst. Examples include amine catalysts such as triethylamine, triethylenediamine, diethanolamine, and tetramethylguanidine, tin catalysts such as stannous octoate and dibutyltin dilaurate, and metal catalysts such as lead octenate (also called organometallic catalysts). The amount of catalyst to be added is preferably 0.001 to 0.5 parts by mass per 100 parts by mass of the urethane prepolymer having an isocyanate group.

[0031] The polyurethane foam composition (A) may appropriately contain other components, such as a compatibilizer, a plasticizer, a foam stabilizer, a synthetic resin stabilizer such as an antioxidant or a light stabilizer, a filler, a colorant, and a flame retardant.

[0032] (2) Manufacturing method of polyurethane foam (part 1) The polyurethane foam (part 1) can be produced by a known foaming method. Foaming may be either slab foaming or mold foaming. Slab foaming is a method in which a mixed polyurethane foam composition is discharged onto a belt conveyer and foamed at atmospheric pressure and room temperature, while mold foaming is a method in which a mixed polyurethane foam composition is filled into a mold (metal mold) and foamed within the mold.

[0033] From the viewpoint of ensuring impact resilience and durability, the isocyanate index (INDEX) in the polyurethane foam composition (A) is, for example, 90 to 170, preferably 120 to 160, and more preferably 130 to 150. The isocyanate index is an index used in the field of polyurethane foams, and is a numerical value that represents the equivalent ratio of isocyanate groups to active hydrogen groups in the polyurethane foam composition, expressed as a percentage [NCO group equivalent / active hydrogen group equivalent×100].

[0034] 3. Polyurethane foam (part 2) The polyurethane foam (part 2) is obtained from a polyurethane foam composition (B) containing polytetramethylene glycol, castor oil polyol, and 1,5-naphthalene diisocyanate.

[0035] In the polyurethane foam composition (B), the explanations for polytetramethylene glycol, castor oil polyol, and 1,5-naphthalene diisocyanate in the section "1. Urethane prepolymer" regarding "(1) Polyol" and "(2) Polyisocyanate" apply as is, and the explanations therefor are omitted.

[0036] The polyurethane foam composition (B) is a composition used in the one-shot method. The polyurethane foam composition (B) may contain, in addition to polytetramethylene glycol, castor oil polyol, and 1,5-naphthalene diisocyanate, a compound having an active hydrogen group and a catalyst. The explanations for the compound having an active hydrogen group and the catalyst in the section "2. Polyurethane foam (part 1)" apply as is, and the description thereof will be omitted. The polyurethane foam (part 2) can be produced by a known foaming method.

[0037] The isocyanate index (INDEX) in the polyurethane foam composition (B) is, for example, 80-120, preferably 90-110, and more preferably 95-105, from the viewpoint of ensuring impact resilience and durability.

[0038] According to polyurethane foam (part 2), the presence of alkyl chains derived from castor oil polyol within the polyurethane straight chain gives the polyurethane flexibility, and it is presumed that the rebound resilience can be improved compared to when only polytetramethylene glycol is used as the polyol.

[0039] 4. Properties and Applications of Polyurethane Foam The physical properties of the polyurethane foam can be appropriately set depending on the application, etc. The polyurethane foam preferably has the following physical properties. (1) Density (apparent density) The density (JIS K7222:2005) is preferably 0.20 g / cm 3 More than 0.50g / cm 3 More preferably, it is 0.25 g / cm 3 More than 0.50g / cm 3 More preferably, it is 0.28 g / cm or less. 3 More than 0.45g / cm 3 The following is the result. (2) Rebound elasticity The rebound resilience (JIS K6255 (Lupke method): 2013) is preferably 70% or more, more preferably 75% or more, and even more preferably 80% or more. The upper limit of the rebound resilience is not particularly limited, and is, for example, 90% or less. (3) Tensile strength The tensile strength (JIS K6251:2017) is preferably 1.5 MPa or more, more preferably 2.0 MPa or more. The upper limit of the tensile strength is not particularly limited, and is, for example, 5.0 MPa or less. (4) Elongation (elongation at break) The elongation (JIS K6251:2017) is preferably 250% or more, more preferably 280% or more, and even more preferably 300% or more. The upper limit of the elongation is not particularly limited, and is, for example, 400% or less.

[0040] (5)Applications The article in which the polyurethane foam is used is not particularly limited. The technology of the present disclosure is suitable for a bat equipped with a polyurethane foam. The polyurethane foam is preferably provided on the hitting portion of a bat for baseball, softball, etc. Specifically, the bat may include a bat body having an attachment portion between the grip end and the tip portion, and a hitting portion in which a polyurethane foam formed in a cylindrical shape is attached to the attachment portion. In addition, the polyurethane foam of the present disclosure is suitable for articles requiring high resilience, such as the soles of sports shoes. EXAMPLES

[0041] 1. Polyurethane foam manufacturing Polyol and isocyanate were mixed in the ratio shown in Table 1 and reacted for about 30 minutes at 130° C. in a nitrogen gas stream to produce a urethane prepolymer (liquid B). The details of each raw material are as follows: Polytetramethylene glycol: Biomass-derived polytetramethylene glycol, functional group number 2, hydroxyl value 53-59mgKOH / g, weight average molecular weight 2000, product number: BioPTMG2000, manufactured by Mitsubishi Chemical Corporation Castor oil polyol: Functionality 2.3, hydroxyl value 72-92gKOH / g, viscosity 700-1600mPa·s / 25℃, product number: URIC H-1830, manufactured by Ito Oil Mills Polyisocyanate: 1,5-naphthalene diisocyanate, NCO%: 40%, product code: Cosmonate ND, manufactured by Mitsui Chemicals

[0042] The working example is an example in which polytetramethylene glycol and castor oil polyol are used as the polyol, and the comparative example is an example in which only polytetramethylene glycol is used as the polyol. The "NCO% of urethane prepolymer" in Table 1 is a theoretical value of NCO% obtained by calculation, and was calculated according to the following formula. NCO% = [[Number of moles of NCO groups - (number of moles of OH groups of polytetramethylene glycol + number of moles of OH groups of castor oil polyol)] x molecular weight of NCO] / [amount of isocyanate + amount of polytetramethylene glycol + amount of castor oil polyol] x 100 [Table 1]

[0043] A mixture containing a compound having an active hydrogen group and a catalyst was prepared as liquid A in the ratio shown in Table 2. A compatibilizer was added to liquid A to adjust the ratio of liquid A and liquid B and to increase the volume of liquid A for stable mixing and stirring. The details of each raw material are as follows: Foaming agent: A mixture of castor oil and water (a compound with active hydrogen groups), product number: Advate SV (castor oil and water weight ratio 50:50), manufactured by Rhein Chemie Japan Catalyst: Amine catalyst, product number: Addocat PP, manufactured by Rhein Chemie Japan Compatibilizer: Polyoxyethylene monooleate, Brownon 200SA, manufactured by Aoki Oil Industries Co., Ltd. [Table 2]

[0044] Liquid B (urethane prepolymer) and Liquid A were mixed in the amounts shown in Table 3 and injected into a mold to produce a polyurethane foam by mold foaming. The mold used had a cavity (molding space) of 200 mm x 110 mm x 30 mm thick. [Table 3]

[0045] 2. Evaluation Method The appearance of the polyurethane foams of the Examples and Comparative Examples was visually observed to evaluate the moldability. When the moldability was good, it was rated as "good". When some molding defects were observed but the foam was usable, it was rated as "fair", and the specific details of the defects were noted in parentheses.

[0046] The density was measured for a test piece (200 mm wide × 110 mm long × 30 mm thick, with skin layers on six sides) in accordance with JIS K7222:2005. The rebound resilience was measured by slicing the test piece to a thickness of 12.5 mm (with the skin layer on the upper surface) and punching it to a diameter of 29 mm to prepare a sample, in accordance with JIS K6255 (Lübke method): 2013, so that the striking end of the Lübke pendulum hit the skin layer. The tensile strength and elongation were measured in accordance with JIS K6251:2017 by slicing the test pieces to a thickness of 2 mm (without the skin layer) and punching them into dumbbell-shaped No. 2 samples.

[0047] 3.Results The results are shown in Table 3. The comparative example is a polyurethane foam using only polytetramethylene glycol as the polyol. The comparative example had a resilience of 70%. The examples are polyurethane foams using polytetramethylene glycol and castor oil polyol as polyols. The impact resilience of the examples was 80%. The moldability of the examples was also "good", which was better than that of the comparative examples. Furthermore, the examples had a density of 0.20 g / cm 3 More than 0.50g / cm3 The density was below 2.0 MPa, which was suitable for practical use. The examples had a tensile strength of 2.0 MPa or more and an elongation of 250% or more, which was suitable for practical use.

[0048] According to the above examples, the impact resilience of the polyurethane foam could be improved by using raw materials derived from biomass.

[0049] The present disclosure is not limited to the embodiments described above in detail, and various modifications and variations are possible within the scope of the present disclosure.

Claims

1. A urethane prepolymer having an isocyanate group at its end, which is a reaction product of a polyol and a polyisocyanate, The polyol includes at least polytetramethylene glycol and castor oil polyol, The polyisocyanate includes 1,5-naphthalene diisocyanate.

2. A polyurethane foam obtained from a polyurethane foam composition comprising the urethane prepolymer according to claim 1.

3. A polyurethane foam obtained from a polyurethane foam composition comprising polytetramethylene glycol, castor oil polyol, and 1,5-naphthalene diisocyanate.

4. A bat comprising the polyurethane foam according to claim 2 or 3.

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