Polyurethane foam and bat

Abstract

To provide a highly adaptable technology capable of improving durability of a polyurethane foam.SOLUTION: A polyurethane foam is derived from a polyurethane foam composition that comprises an isocyanate component and a compound with an active hydrogen group. The isocyanate component is an urethane prepolymer with an isocyanate group, derived from a composition that comprises a polyol and a polyisocyanate. An isocyanate index of the polyurethane foam composition is more than 120 and 170 or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to polyurethane foams and bats.

Background Art

[0002] Patent Document 1 describes a polyurethane foam obtained from a composition for a polyurethane foam containing an isocyanate component, a foaming agent, and a catalyst. The isocyanate component is a urethane prepolymer having an isocyanate group obtained from a polyol component, a polyrotaxane which is a compound having an active hydrogen group and has a cyclic portion, and an isocyanate. According to such a configuration, the durability against breakage, sagging, etc. can be improved.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The isocyanate component of Patent Document 1 is obtained from special raw materials. In order to improve the durability of the polyurethane foam, a highly versatile technique applicable to isocyanate components obtained from various raw materials is desired.

[0005] [[ID=!38]] The present disclosure has been made in view of the above circumstances, and an object thereof is to provide a highly versatile technique capable of improving the durability of a polyurethane foam. The present disclosure can be realized in the following forms.

Means for Solving the Problems

[0006] A polyurethane foam obtained from a composition for a polyurethane foam containing an isocyanate component and a compound having an active hydrogen group, It should be noted that there seems to be an incorrect tag ID in the original text where ID=19 is likely a misprint as it's repeated with an exclamation mark in the translation process. This might need to be corrected in the original source for proper handling in future translations.The isocyanate component is a urethane prepolymer having isocyanate groups obtained from a composition containing a polyol and a polyisocyanate. A polyurethane foam having an isocyanate index greater than 120 and 170 or less. [Effects of the Invention]

[0007] According to this disclosure, we can provide a highly versatile technology that can improve the durability of polyurethane foams. [Modes for carrying out the invention]

[0008] Herein lies a preferred example of this disclosure. The polyol in question is a polyurethane foam containing a bifunctional polyol. The polyurethane foam comprises a trifunctional polyether polyol with a weight-average molecular weight of 1,000-10,000. The polyurethane foam comprises 1,5-naphthalenediisocyanate as the polyisocyanate. A bat equipped with the polyurethane foam described above.

[0009] The disclosure is described in detail below. In this specification, when a numerical range is indicated using "-", it includes both the lower and upper limits unless otherwise specified. For example, the expression "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".

[0010] 1. Polyurethane foam The polyurethane foam is obtained from a polyurethane foam composition comprising an isocyanate component and a compound having an active hydrogen group, wherein the isocyanate component is a urethane prepolymer having an isocyanate group obtained from a composition comprising a polyol and a polyisocyanate, and the isocyanate index of the polyurethane foam composition is greater than 120 and 170 or less.

[0011] (1) Isocyanate component The isocyanate component is a urethane prepolymer having isocyanate groups obtained from a composition containing a polyol and polyisocyanate. The prepolymerization method using the urethane prepolymer facilitates the adjustment of the crystal distribution between soft and hard segments, making it easier to form a regular crystalline structure. As a result, a urethane elastomer with good crystallinity can be suitably obtained, improving the mechanical strength and durability of the polyurethane foam. The NCO% of the urethane prepolymer is not particularly limited. From the viewpoint of mechanical strength, flexibility, and durability, the NCO% of the urethane prepolymer is preferably 2.5% to 5.0%, and more preferably 3.0% to 5.0%.

[0012] (1-1) Polyol The polyol is not particularly limited. Preferably, the polyol includes a bifunctional polyol. Examples of bifunctional polyols include polytetramethylene glycol, polytrimethylene glycol, and polyalkylene glycol. Only one type of bifunctional polyol may be used, or two or more types may be used in combination. From the viewpoint of improving rebound elasticity, the bifunctional polyol is preferably polytetramethylene glycol and / or polytrimethylene glycol, and more preferably polytetramethylene glycol. Polytetramethylene glycol is a polyol having repeating units represented by [-CH2CH2CH2CH2-O-].

[0013] 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 mg KOH / g or more and 200 mg KOH / g or less, more preferably 25 mg KOH / g or more and 150 mg KOH / g or less, and even more preferably 30 mg KOH / g or more and 120 mg KOH / g or less. In this disclosure, the weight-average molecular weight of the polyol is measured by gel permeation chromatography (GPC). If the polyol is a commercially available product, the catalog value may be used as the weight-average molecular weight.

[0014] From the viewpoint of improving the rebound modulus of polyurethane foam, the polytetramethylene glycol content is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, and even more preferably 70 parts by mass or more, when the total polyol is 100 parts by mass. The upper limit of the polytetramethylene glycol content may be 100 parts by mass or 95 parts by mass or less. From these viewpoints, the polytetramethylene glycol content is preferably 50 parts by mass or more and 100 parts by mass or less, more preferably 60 parts by mass or more and 100 parts by mass or less, and even more preferably 70 parts by mass or more and 95 parts by mass or less, when the total polyol is 100 parts by mass.

[0015] The polyol may contain a trifunctional polyether polyol with a weight-average molecular weight of 1,000-10,000, from the viewpoint of ensuring moldability. The polyether polyol is not particularly limited as long as it has three functional groups and a weight-average molecular weight of 1,000-10,000. In the following description, this polyol will also be referred to as a trifunctional polyether polyol. Only one type of trifunctional polyether polyol may be used, or two or more types may be used in combination.

[0016] The trifunctional polyether polyol can be obtained by randomly or blockwise, preferably blockwise, ring-opening addition of one or more alkylene oxides to a compound having three active hydrogen-containing groups. Examples of the alkylene oxide to be ring-opening added include ethylene oxide, propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, styrene oxide, and the like. The polyether polyol is preferably a polyether polyol containing at least propylene oxide units, more preferably a polyethylene oxide-polypropylene oxide copolymer, and even more preferably a polyethylene oxide-polypropylene oxide block copolymer with polyethylene oxide added to both ends.

[0017] The weight average molecular weight of the trifunctional polyether polyol is 1000 - 10000, preferably 2500 - 9000, and more preferably 4000 - 8000. The hydroxyl value of the polyether polyol is preferably 15 mgKOH / g or more and 180 mgKOH / g or less, more preferably 18 mgKOH / g or more and 70 mgKOH / g or less, and even more preferably 20 mgKOH / g or more and 45 mgKOH / g or less. When the total amount of the polyol is 100 parts by mass, the content of the trifunctional polyether polyol is 0 parts by mass or more, preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 7 parts by mass or more. The content of the trifunctional polyether polyol is, for example, 50 parts by mass or less.

[0018] When using polytetramethylene glycol and trifunctional polyether polyol in combination, the mass ratio of polytetramethylene glycol to trifunctional polyether polyol is not particularly limited. From the perspective of ensuring the resilience of the polyurethane foam and improving the moldability, the mass ratio of polytetramethylene glycol to trifunctional polyether polyol (polytetramethylene glycol:trifunctional polyether polyol) is 100:0 - 50:50, preferably 100:0 - 60:40, and more preferably 95:5 - 70:30.

[0019] The polyol may contain polyols other than polytetramethylene glycol and trifunctional polyether polyol (other polyols). Even in that case, the content of other polyols is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less.

[0020] (1 - 2) Polyisocyanate For the polyisocyanate, known aromatic isocyanates, alicyclic isocyanates, and aliphatic isocyanates used in the production of polyurethane foams can be used. Examples of aromatic isocyanates include 1,5 - naphthalene diisocyanate (NDI), tolylene diisocyanate (TDI), 4,4’ - diphenylmethane diisocyanate (MDI), polymeric MDI (crude MDI), xylylene diisocyanate, dimethylbiphenyl diisocyanate (TODI), etc. Examples of alicyclic isocyanates include cyclohexane - 1,4 - diisocyanate, isophorone diisocyanate, hydrogenated MDI, etc. Examples of aliphatic isocyanates include hexamethylene diisocyanate, isopropylenediisocyanate, methylene diisocyanate, etc.

[0021] From the perspective of improving the resilience ratio of the polyurethane foam, the polyisocyanate preferably contains at least 1,5 - naphthalene diisocyanate, and preferably contains only 1,5 - naphthalene diisocyanate.

[0022] (2) Compounds having an active hydrogen group Compounds having active hydrogen groups are preferred, and these compounds have a number-average molecular weight of 18-1000. Examples of compounds having active hydrogen groups include water, polyethylene glycol, polypropylene glycol, polyester polyol, and castor oil. Among these, water is preferred. When the compound having active hydrogen groups is water, it reacts with the urethane prepolymer to generate carbon dioxide, and foaming occurs due to this carbon dioxide. When the compound having active hydrogen groups is water, it is more preferable to use it in combination with an emulsifier. Examples of emulsifiers 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, and cationic emulsifiers such as alkylamine salts and alkyltrimethylammonium salts, which may be used alone or in combination of two or more. The amount of water added is preferably 0.3 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the urethane prepolymer having isocyanate groups. The amount of emulsifier added is preferably 0.01 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the urethane prepolymer having isocyanate groups.

[0023] (3) Other ingredients The polyurethane foam composition may contain other components as appropriate. These other components may include catalysts, plasticizers, compatibilizers, foam stabilizers, synthetic resin stabilizers such as antioxidants and light stabilizers, fillers, colorants, and flame retardants. Furthermore, the polyurethane foam composition may contain foaming aids in addition to foaming agents.

[0024] As catalysts included in the polyurethane foam composition, known urethane catalysts can be used. Examples include amine catalysts such as triethylamine, triethylenediamine, diethanolamine, and tetramethylguanidine, tin catalysts such as stanus octoate and dibutyltin dilaurate, and metal catalysts such as lead octenoate (also called organometallic catalysts). The amount of catalyst blended is preferably 0.001 parts by mass or more and 0.5 parts by mass or less per 100 parts by mass of urethane prepolymer having isocyanate groups.

[0025] (4) Isocyanate index of polyurethane foam composition From the viewpoint of improving durability, the isocyanate index of the polyurethane foam composition is greater than 120, preferably greater than 125, more preferably 130 or higher, and even more preferably 140 or higher, or 145 or higher. From the viewpoint of improving moldability, the isocyanate index of the polyurethane foam composition is 170 or lower, preferably 165 or lower, and more preferably 160 or lower. From these viewpoints, the isocyanate index of the polyurethane foam composition is greater than 120 and 170 or lower, preferably greater than 125 and 165 or lower, and more preferably 130 or higher and 160 or lower. The isocyanate index is an index used in the field of polyurethane foams, and is a numerical value expressed as a percentage of the equivalent ratio of isocyanate groups to active hydrogen groups in the polyurethane foam composition [equivalent of NCO groups / equivalent of active hydrogen groups × 100].

[0026] The reason why the durability of polyurethane foam can be improved when the isocyanate index of the polyurethane foam composition is greater than 120 and 170 or less is not clear, but it is presumed to be as follows. This disclosure is not to be interpreted as being limited to this presumed reason. Polyurethane foams become brittle and less durable when the proportion of urea bonds in the polyurethane is high. Urea bonds in polyurethane are formed, for example, when the compound having an active hydrogen group is water, as follows: When the isocyanate component contained in the polyurethane foam composition reacts with water, an amine and carbon dioxide are produced. The produced amine reacts with the excess isocyanate component, extending the chain by producing urea. On the other hand, the water contained in the polyurethane foam composition consumes the isocyanate component, thus hindering the main reaction, urethane formation. In other words, when the NCO% of the isocyanate component is the same, a smaller amount of water suppresses the formation of urea bonds and promotes the formation of urethane bonds, etc. This is thought to lower the proportion of urea bonds in the polyurethane and improve the durability of the polyurethane foam. When the NCO% of the isocyanate component is the same, the isocyanate index [equivalent amount of NCO groups / equivalent amount of active hydrogen groups × 100] becomes larger as the equivalent amount of active hydrogen groups (amount of water) decreases. In other words, a high isocyanate index in a polyurethane foam composition is one indicator of a low amount of water, i.e., a low ratio of urea bonds in the polyurethane. Thus, it is presumed that by making the isocyanate index higher than a predetermined value (e.g., 120), the ratio of urea bonds in the polyurethane can be suppressed, thereby improving the durability of the polyurethane foam.

[0027] 2. Method for manufacturing polyurethane foam Polyurethane foam is produced by reacting the isocyanate component of a polyurethane foam composition with a compound having an active hydrogen group, and then foaming the mixture. Foaming can be done by either slab foaming or mold foaming. Slab foaming is a method in which a mixed polyurethane foam composition is discharged onto a belt conveyor 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 and foamed within the mold.

[0028] 3. Physical properties and applications of polyurethane foam The physical properties of polyurethane foam can be appropriately set according to the application and other factors. Polyurethane foam preferably possesses the following physical properties: (1) Density (apparent density) The density (JIS K7222:2005) is preferably 0.20 g / cm³. 3 More than 0.60g / cm 3 The following, and more preferably 0.30 g / cm³ 3 More than 0.60g / cm 3 The following applies: (2) Tensile strength The tensile strength (according to JIS K6251:2017 (Dumbbell-shaped No. 2)) is preferably 2.0 MPa or higher, more preferably 2.5 MPa or higher, and even more preferably 3.0 MPa or higher. The upper limit of the tensile strength is not particularly limited, and is, for example, 5.0 MPa or lower. (3) Elongation (elongation at break) The elongation (JIS K6251:2017) is preferably 250% or more, more preferably 300% or more, and even more preferably 350% or more. The upper limit of the elongation is not particularly limited, and is, for example, 500% or less.

[0029] (4) Rebound The polyurethane foam preferably has a rebound of 55% or more, more preferably 60% or more, and even more preferably 70% or more. The upper limit of the rebound is not particularly limited, but 85% is an example. The rebound was measured using a commercially available pitching machine. A ball (M-size ball, approved by the All Japan Amateur Baseball Federation) was launched from the pitching machine and struck a test piece (200mm wide x 110mm long x 30mm thick) fixed to a vertical concrete wall, ensuring that the ball did not deviate from the test piece (more preferably near the center of the test piece). The velocity of the ball before impact with the test piece and the velocity of the ball after it bounced back were measured, and the rebound was calculated using the following formula. Rebound (%) = Speed ​​of the bounced ball / Speed ​​of the ball before impact × 100

[0030] The distance between the pitching machine's launch port and the concrete wall is 1 meter, and the ball's speed upon impact with the test piece surface is 100 km / h. The velocity of the ball before impact with the test piece and the velocity of the ball after it bounced back were measured by installing a velocity measurement board with vertical lines drawn at 100mm intervals from 500mm to 200mm from the concrete wall, next to the ball's path near the test piece. The ball's tip crossed the vertical lines on the velocity measurement board and impacted the test piece. A high-speed camera was used to photograph the ball's movement until the tip of the bounced ball passed 500mm from the concrete wall. The time it took for the ball's tip to travel 300mm before impact with the test piece (the distance from 500mm to 200mm from the concrete wall) was measured. The time it took for the ball to bounce off the test piece and travel 300mm from the test piece (the distance from 200mm to 500mm from the concrete wall) was also measured. The velocity of the ball before impact was calculated from the ball's travel distance of 300mm and the measured time until the ball impacted the test piece. The velocity of the bounced ball was calculated from the distance the ball traveled (300 mm) and the time elapsed after it bounced off the measured test piece.

[0031] The thickness of the test piece (polyurethane foam) is preferably 15 mm or more, and more preferably 25 mm or more. There is no particular upper limit to the thickness of the test piece, but it is preferably less than 50 mm, and more preferably less than 40 mm. If the thickness of the test piece is less than 15 mm, there is a possibility that the ball will bottom out when it hits the test piece, and the rebound properties of the test piece itself may not be properly evaluated. The rebound properties of the polyurethane foam in this disclosure were evaluated with a test piece thickness of 30 mm.

[0032] (5)Durability The polyurethane foam of this disclosure preferably has a durability of 300 or more drops before failure in the following drop impact test. There is no particular upper limit to the number of drops before failure. In the drop test, a test piece consisting of an annular shape with an outer diameter of 30 mm, an inner diameter of 10 mm, and a height of 30 mm is inserted onto a shaft protruding from a metal plate, and a sleeve is placed over the test piece along the shaft. A 50 kg weight is dropped from a position 110 mm above the sleeve at intervals of 6 times per minute, impacting the top surface of the test piece, and the number of impacts before the test piece fails is measured. The weight is made of metal with a dense interior (not hollow inside) and is disc-shaped with a diameter larger than the outer diameter of the test piece.

[0033] The drop height for the weight in the drop impact test is set for the following reason: The All Japan Amateur Baseball Federation certified ball, size M, weighs approximately 138g (0.138kg), and the kinetic energy when it collides with the hitting part of a bat at a speed of 100km / h is approximately 53J. On the other hand, when a 50kg weight is allowed to free fall, the drop distance (height) at which the potential energy is approximately 53J is approximately 110mm (0.110m), and the drop height for the drop impact test was set to 110mm above the sleeve. However, this drop impact test uses a metal weight, and the impact when dropped onto the test piece is greater compared to the All Japan Amateur Baseball Federation certified ball, which is soft and hollow inside.

[0034] (6)Applications The articles in which polyurethane foam is used are not particularly limited. The technology of this disclosure is suitable for bats equipped with polyurethane foam. The polyurethane foam is preferably provided in the hitting portion of a bat for baseball, softball, etc. Specifically, the bat may comprise a bat body having a mounting portion between the grip end and the tip, and a hitting portion in which a cylindrical polyurethane foam is attached to the mounting portion. In addition, the polyurethane foam of this disclosure is suitable for articles requiring high resilience and durability, such as the soles of sports shoes. [Examples]

[0035] 1. Preparation of NCO-terminated urethane prepolymer (liquid B) Polyols and isocyanates were mixed in the proportions shown in Table 1 and reacted at 130°C for approximately 30 minutes under a nitrogen gas stream to prepare a urethane prepolymer (solution B). Details of each ingredient are as follows: • Polyol 1: Polytetramethylene glycol, 2 functional groups, hydroxyl value 56 mgKOH / g, number average molecular weight 2000, catalog number; PTG2000, manufactured by Hodogaya Chemical Co., Ltd. • Polyol 2: Polyether polyol, 3 functional groups, hydroxyl value 29 mgKOH / g, weight-average molecular weight 6000, catalog number: Preminol 7001K, manufactured by Asahi Glass Co., Ltd. • Isocyanate (NDI); 1,5-naphthalene diisocyanate, NCO%; 40%, catalog number; Cosmonate ND, manufactured by Mitsui Chemicals, Inc. Polyol 1 corresponds to a bifunctional polyol. Polyol 2 corresponds to a trifunctional polyether polyol with a weight-average molecular weight of 1000-10000.

[0036] The "NCO% of urethane prepolymer" in Table 1 represents the theoretical value of NCO% obtained through calculation, and was calculated using the following formula. NCO% = [[Moles of NCO group - (Moles of polytetramethylene glycol + Moles of polyether polyol)] × Molecular weight of NCO] / [Amount of isocyanate + Amount of polytetramethylene glycol + Amount of polyether polyol] × 100 [Table 1]

[0037] As Solution A, a compound containing a compound having an active hydrogen group and a catalyst was prepared in the proportions shown in Table 2. In Solution A, a plasticizer was added to ensure an appropriate mixing ratio between the NCO-terminated urethane prepolymer and the foaming liquid, and to ensure stable mixing and stirring. Details of each ingredient are as follows: • Foaming agent: A mixture containing water and an emulsifier (a mixture of sodium salt of sulfonated castor oil, sodium salt of highly sulfonated fatty acid, etc.), product number; Advade SV (weight ratio of water to emulsifier 50:50), manufactured by Rhein Chemie Japan. • Plasticizer: Diisononyl adipate (DINA), manufactured by Daihachi Chemical Co., Ltd. • Catalyst: Amine catalyst, Part number: Addocat PP, manufactured by Rhein Chemie Japan Co., Ltd. [Table 2]

[0038] Liquid B (urethane prepolymer) and liquid A were mixed in the proportions 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) measuring 200 mm x 110 mm x 30 mm in thickness. The isocyanate index of the polyurethane foam composition in Example 1 is 151. The isocyanate index of the polyurethane foam composition in Example 2 is 156. 。 [Table 3]

[0039] 2. Evaluation Method Density was measured in accordance with JIS K7222:2005 for a test piece (200mm wide x 110mm long x 30mm thick, with a skin layer on all six sides). Tensile strength and elongation were measured in accordance with JIS K6251:2017 by slicing a test piece to a thickness of 2 mm (without the skin layer), punching out a dumbbell-shaped sample (size 2), and performing the measurements. The appearance was evaluated visually to assess moldability. Good moldability was marked "Good," while poor moldability was marked "Poor." "-" indicates that moldability was not evaluated. Rebound properties were evaluated using the test piece (200 x 110 x 30 mm) as is (with skin layers on all top, bottom, and sides) and the method described in the embodiment. "-" indicates that rebound properties were not evaluated. Durability was assessed by creating a test piece from the test piece (200 x 110 x 30 mm) that had an annular shape with an outer diameter of 30 mm, an inner diameter of 10 mm, and a height of 30 mm (with a skin layer only on the top and bottom surfaces). The presence or absence of damage was evaluated when a weight was dropped 300 times in the drop impact test described in the embodiment. The evaluation was based on the following criteria. Good: The polyurethane foam is usable, with at least a portion of the test piece failing after more than 300 cycles. Defective: The number of cycles until at least part of the test piece breaks is less than 300, or the polyurethane foam is unsuitable for practical use.

[0040] 3.Results The results are shown in Table 3. The comparative example had an isocyanate index of 120 or less for the polyurethane foam composition. The comparative example showed damage in a drop impact test and had poor durability. Examples 1 and 2 are polyurethane foam compositions with an isocyanate index greater than 120 and less than or equal to 170. Examples 1 and 2 showed no damage in drop impact tests and demonstrated good durability.

[0041] Examples 1 and 2 exhibited a rebound of 70% or more, demonstrating sufficient rebound properties. Furthermore, Examples 1 and 2 had a density of 0.30 g / cm³. 3 More than 0.60g / cm 3 The density was suitable for practical use, as described below. Examples 1 and 2 had a tensile strength of 2.0 MPa or higher and an elongation of 250% or higher, indicating suitable mechanical strength for practical use. Examples 1 and 2 had a good appearance and were polyurethane foams suitable for practical use.

[0042] The above examples demonstrate a highly versatile technology that can improve the durability of polyurethane foams.

[0043] This disclosure is not limited to the embodiments detailed above, and various modifications or changes are possible within the scope of this disclosure.

Claims

1. A polyurethane foam obtained from a composition for polyurethane foams comprising an isocyanate component and a compound having an active hydrogen group, The isocyanate component is a urethane prepolymer having isocyanate groups obtained from a composition containing a polyol and a polyisocyanate. The isocyanate index of the aforementioned polyurethane foam composition is greater than 120 and less than or equal to 170. The aforementioned polyols include a difunctional polyol and a trifunctional polyether polyol with a weight-average molecular weight of 1,000 to 10,000. The polyurethane foam comprises 1,5-naphthalenediisocyanate as the polyisocyanate.

2. A bat comprising the polyurethane foam described in claim 1.

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