JP2017176744A - Foamed polyurethane material for ball hitting bat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foamed polyurethane material for a ball hitting bat which is a foamed polyurethane material using PTMG and MDI-based isocyanate, which is high in processability, can be manufactured easily, and satisfies a high modulus of repulsion elasticity while satisfying toughness even when balls are hit repeatedly.SOLUTION: A foamed polyurethane material for a ball hitting bat is composed of a cured material of a composition containing polytetramethyleneglycol, diphenylmethane diisocyanate-based isocyanate, a foaming agent, a catalyst, a foam stabilizer, and a cell opener. The apparent density is 250-500 kg/m, the closed cell ratio is 0-20%, and the modulus of repulsion elasticity is 50-75%.SELECTED DRAWING: None

Description

  The present invention relates to a foamed polyurethane material for a hit ball bat.

2. Description of the Related Art Conventionally, a hitting ball bat including a hitting ball portion, a tapered portion, and a grip portion, in which a recess is formed around at least a hitting ball portion, and an elastic body that forms an outer peripheral surface of the hitting ball portion in this recess is covered and integrated is known ( Patent Document 1). This hitting bat is popular because the flight distance of the hit ball is increased.
The urethane foam material used as the elastic body of the hit ball bat is superior in rebound resilience and compression set to extend the distance of the hit ball, and is not torn by impact during hitting. It is also required to have excellent toughness while maintaining softness. As such a foamed urethane material, a special foamed polyurethane material using a prepolymer obtained from polyester polyol and naphthalene isocyanate is suitably used.

Japanese Patent Laid-Open No. 2015-16039

  However, this special foamed polyurethane material has the following characteristics: 1) It is difficult to improve the rebound resilience any more, 2) The storage stability of the prepolymer is poor, and it must be used up on the day of synthesis. Therefore, there are many problems such as that the obtained polyurethane foam material is easily hydrolyzed, and 4) the raw material is expensive.

  Therefore, a polyurethane foam material using polytetramethylene glycol (hereinafter also referred to as “PTMG”) and diphenylmethane diisocyanate (MDI) -based isocyanate (hereinafter also referred to as “MDI-based isocyanate”) as a versatile and inexpensive raw material. Is being considered.

The foamed polyurethane material using PTMG and MDI isocyanate can increase the density of 250 to 500 kg / m ³ and satisfy the toughness by using a foam stabilizer, catalyst, etc. (Self-foaming), so if it is removed from the mold by heating (cure) in a short time, it will expand at the time of demolding and will shrink easily after cooling, resulting in unstable product dimensions or partial deformation For this reason, it is necessary to remove the mold after a long time of heating (curing) to obtain sufficient green strength. In addition, the finished product has a high compression set due to the self-foaming. Reducing the amount of catalyst used as a measure against this self-foaming causes unreacted product skin tears, foam deformation, foam breakage, etc. during short-time demolding. On the other hand, long-time demolding has low processability (productivity). .
Furthermore, since the closed-cell foamed polyurethane material becomes open-celled every time it is compressed due to impact, the resilience modulus and toughness change over time.
Thus, it has become clear that the foamed polyurethane material using PTMG and MDI-based isocyanate needs to be improved for use as a hitting ball bat.

  Therefore, in consideration of the above facts, the present invention is a foamed polyurethane material using PTMG and MDI-based isocyanate, which has high processability and is easy to manufacture, and is highly repulsive while satisfying toughness even by repeated hitting. It is an object to provide a urethane foam material for a hitting ball bat that satisfies the elastic modulus.

  The above problem is solved by the following means.

<1>
A cured product of a composition comprising polytetramethylene glycol, diphenylmethane diisocyanate-based isocyanate, a foaming agent, a catalyst, a foam stabilizer, and a cell opener;
A foamed polyurethane material for a hitting ball bat having an apparent density of 250 to 500 kg / m ³ , a closed cell ratio of 0 to 20%, and a rebound resilience of 50 to 75%.
<2>
The cell opener is at least one selected from the group consisting of a low molecular diol, a polypropylene glycol-based bifunctional polyol, a polyether acetate ester, a polybutene, and a paraffinic oil. Polyurethane material.
<3>
The foamed polyurethane material for a ball bat according to <2>, wherein the polypropylene glycol-based bifunctional polyol is a bifunctional polyol having an ethylene oxide content of 0 to 80 mol% and a number average molecular weight Mn of 400 to 4000.
<4>
The foamed polyurethane material for a hitting ball bat according to any one of <1> to <3>, wherein the composition further contains a polyfunctional polyol having 3 or more functional groups, and a 30% compression set is 15% or less.

  According to the present invention, a foamed polyurethane material using PTMG and MDI-based isocyanate, which has high processability and is easy to manufacture, and satisfies the toughness and the high rebound resilience while being repeatedly hit. A urethane foam material for bats can be provided.

  Embodiments that are examples of the present invention will be described below.

The foamed urethane material for a ball striking bat according to the present embodiment (hereinafter also referred to as “foamed urethane material”) includes polytetramethylene glycol (PTMG), diphenylmethane diisocyanate-based isocyanate (MDI-based isocyanate), a foaming agent, and a catalyst. And a cured product of a composition comprising a foam stabilizer and a cell opener.
The foamed polyurethane material has an apparent density of 250 to 500 kg / m ³ , a closed cell ratio of 0 to 20%, and a rebound resilience of 50 to 75%.

The foamed polyurethane material according to the present embodiment is obtained by reacting and foaming PTMG and MDI isocyanate together with a foaming agent, a catalyst, and a foam stabilizer in the presence of a cell opener. Depending on the ingredients of this raw material, the apparent density is in the above range as well as the toughness and the impact resilience are improved. Furthermore, due to the presence of the cell opener, the closed cell ratio is easily reduced to form continuous bubbles, and even when subjected to compression, changes in toughness and rebound elastic modulus over time are suppressed. And at the time of mold removal, generation | occurrence | production of expansion | swelling, shrinkage | contraction, skin tear, foam deformation | transformation, foam breakage, etc. is suppressed, and workability is high.
For this reason, the foamed polyurethane material according to the present embodiment is a foamed urethane material for a hitting ball bat that has high processability and is easy to manufacture, and that satisfies the toughness and satisfies the high rebound resilience even by repeated hitting.
And the hitting bat using the polyurethane foam material according to the present embodiment is not easily torn by impact at the time of hitting, and can increase the flight distance of the hit ball even by repeated hitting.

  Hereinafter, the details of the polyurethane foam material according to the present embodiment will be described.

  The composition for forming the urethane foam material according to the present embodiment includes PTMG, MDI-based isocyanate, a foaming agent, a catalyst, a foam stabilizer, and a cell opener. This composition may further contain a polyfunctional polyol having 3 or more functional groups. In particular, when the composition contains a polyfunctional polyol, the 30% compression set of the foamed urethane material is reduced (for example, the 30% compression set is reduced to 15% or less), and the hitting ball of the hitting bat using the foamed urethane material is used. The flight distance becomes easier to extend.

(PTMG)
Examples of PTMG include polyalkylene glycol obtained by ring-opening polymerization of tetrahydrofuran. PTMG may be a polyalkylene glycol having other alkylene structural units (ethyleneoxy structural units, propyleneoxy structural units, etc.) in addition to the tetramethyleneoxy structure. However, PTMG may have a tetramethyleneoxy structural unit of 50% by weight or more (preferably 80% by weight or more, more preferably 90% by weight or more).
PTMG may be used alone or in combination of two or more.

The number average molecular weight Mn of PTMG is preferably 650 to 3500, and more preferably 1000 to 3000.
When the number average molecular weight Mn of PTMG is within the above range, the resulting urethane material has high elongation, so it is tough and excellent in impact resilience. Furthermore, it is preferable because the hardness hardly increases even at low temperatures.

  Here, the number average molecular weight Mn is the molecular weight when the number of functional groups is determined as 2 from the measured value of the hydroxyl value according to JIS K0070. The average molecular weight of other components is measured in the same manner.

The content of PTMG is preferably 50 to 80% by weight, more preferably 55 to 75% by weight, based on the total solid content of the composition.
When the content of PTMG is within the above range, the resulting urethane material has high elongation, so that it is tough and excellent in impact resilience. Furthermore, it is preferable because the hardness hardly increases even at low temperatures.

(MDI isocyanate)
MDI-based isocyanate is an isocyanate having a diphenylmethane diisocyanate skeleton.
As the MDI-based isocyanate, diphenylmethane diisocyanate (MDI), crude MDI (cr-MDI), 4.4′-diphenylmethane diisocyanate (4.4′-MDI), 2.4′-MDI, 2.2′-MDI , Crude MDI (cr-MDI), carbodiimide-modified MDI, prepolymer-modified MDI, and the like. Among these, prepolymer-modified isocyanate which is a modified body of 4.4′-MDI and 4.4′-MDI is preferable because of high reactivity and excellent toughness and rebound resilience of the obtained urethane material.
One type of MDI isocyanate may be used alone, or two or more types may be used in combination.

The content of the MDI isocyanate is preferably 15 to 40 parts by weight, and more preferably 20 to 30 parts by weight with respect to PTMG.
When the content of the MDI isocyanate is within the above range, the balance between toughness and rebound resilience of the urethane material to be obtained is optimal, which is preferable.

Here, as prepolymer-modified isocyanate (MDI isocyanate-containing prepolymer), ethylene glycol, propylene glycol, 1,3- or 1,4-butanediol, 1,6-hexanediol, neopentyl glycol and 1,10 -C2-C18 divalent alcohols such as decanediol; PPG glycol; PTGM glycol; Prepolymer modified isocyanate in which MDI isocyanate is modified with polycarbonate glycol or the like. In this prepolymer-modified isocyanate, the content of the MDI-based isocyanate with respect to the prepolymer is 10% by weight or more and 50% by weight or less (preferably 15% by weight or more and 45% by weight or less) from the viewpoint of toughness, impact resilience, and low temperature characteristics. There should be.
In addition, it is preferable that content of a MDI type isocyanate containing prepolymer is 20-100 weight part with respect to PTMG, and 30-80 weight part is more preferable.

(Foaming agent)
Examples of the foaming agent include water, low-boiling organic solvents (such as cyclopentane and dichloromethane), halogenated hydrocarbons, and mixed solutions thereof. Further, foaming by a so-called mechanical flossing method in which an inert gas such as air or nitrogen is agitated with a Oaks mixer or the like and bubbles are entrained in the raw material to be used is also preferable. A foaming agent may be used individually by 1 type, and may be used together 2 or more types.
When the foaming agent is water, the addition amount is preferably 0.1 to 3.0 parts, more preferably 0.5 to 1.2 parts with respect to 100 parts by weight of PTMG. When water is used as the foaming agent, the smaller the amount added, the lower the three-dimensional crosslink density of the foam, and the higher the resilience elastic modulus, the better for the rebound of the hit ball. On the other hand, if the amount of water added is small, there is a possibility of insufficient filling during molding, so the amount added needs to be determined in consideration of shape and performance.

(catalyst)
Examples of the catalyst include an organometallic compound catalyst and an amine catalyst.
Examples of the organometallic compound catalyst include tin-based, titanium-based, bismuth-based, nickel-based organometallic catalysts such as organotin compounds such as stannous octylate and stannic dibutyllaurate. is there.
Examples of amine-based catalysts include amine-based catalysts such as monoamines, diamines, triamines, cyclic amines, alcohol amines, ether amines, and the like, for example, triethylenediamine, triethylamine, n-methylmorpholine, n-ethyl. Formoline, N, N, N ′, N′-tetramethylbutanediamine and the like.
A catalyst may be used individually by 1 type and may be used together 2 or more types.

(Foam stabilizer)
Examples of the foam stabilizer include silicone compounds, fluorine compounds, and the like, which are representative examples of copolymers of polydimethylsiloxane and polyoxyalkylene polyol. One type of foam stabilizer may be used alone, or two or more types may be used in combination.
The content of the foam stabilizer is preferably 0.3 to 3 parts by weight, and more preferably 0.5 to 2 parts by weight with respect to PTMG.

(Cell opener)
The cell opener is a component that functions as a defoaming agent or an antifoaming agent.
As cell openers, well-known foam breakers such as low-molecular diols, polypropylene glycol monofunctional or bifunctional polyols, polyether acetates, polybutenes, liquid polybutadiene, polyethylene wax, paraffinic oils, long-chain aliphatic alcohols, etc. Or an antifoamer is mentioned. However, addition of a polypropylene glycol-based monofunctional polyol is not preferable because it causes an increase in compression set and a decrease in tensile strength / elongation.

  Among these, as a cell opener, from the viewpoint of effectively reducing the closed cell ratio of the urethane foam material, from the viewpoint of not adversely affecting other physical properties and not deteriorating the appearance of the product, a low molecular diol, a polypropylene glycol type At least one selected from the group consisting of bifunctional polyols, polyether acetates, polybutenes, and paraffinic oils is preferred, and in particular, polypropylene glycol-based bifunctional polyols (hereinafter also referred to as “PPG-based bifunctional polyols”). preferable. Since this PPG-based bifunctional polyol has a functional group, it does not become a small molecule that bleeds out when it is made into a product, so the adhesive or double-sided tape peels off when it is attached to the bat core in post-processing. hard. Further, since the functional group adheres firmly to the skin material or the bat core during molding, idling due to peeling hardly occurs. Furthermore, since printing is usually performed on the inner surface of a transparent skin material, there is little fear that the adhesiveness with the printing ink is impaired.

As the PPG-based bifunctional polyol, propylene oxide (hereinafter also referred to as “PO”) is added to a dihydric alcohol, or other alkylene oxides other than propylene oxide and propylene oxide (hereinafter also referred to as “EO”). And the like). The addition polymerization of propylene oxide and other alkylene oxides may be random addition polymerization or block addition polymerization.
Here, examples of the divalent alcohol include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1,10-decanediol, and the like. And a divalent alcohol having 2 to 10 carbon atoms.

The number average molecular weight Mn of the PPG single bifunctional polyol is preferably 100 to 10,000, more preferably 400 to 4000.
When the number average molecular weight Mn of the PPG-based bifunctional polyol is in the above range, the cell is not roughened because the effect of reducing the closed cell rate is moderate, there is no adverse effect on other physical properties, and the product appearance is good. preferable.

Among these, the PPG-based bifunctional polyol has an ethylene oxide content of 0 to 80 mol% (preferably 0) from the viewpoint of effectively reducing the closed cell ratio of the foamed urethane material, toughness and low temperature characteristics. And a bifunctional polyol having a number average molecular weight Mn of 100 to 10,000 (preferably 400 to 4000).
Here, the ethylene oxide content is the ratio (molar ratio) of ethylene oxide to the total content of addition-polymerized alkylene oxide.

  A cell opener may be used individually by 1 type, and may be used together 2 or more types.

The content of the cell opener is preferably 1 to 15 parts by weight, more preferably 2 to 10 parts by weight with respect to PTMG.
When the content of the cell opener is within the above range, it is preferable since the closed cell ratio can be reduced without adversely affecting the product appearance.

(Polyfunctional polyol)
Examples of the polyfunctional polyol having 3 or more functional groups include a trifunctional polyol. Examples of the trifunctional polyol include polyether polyols obtained by addition polymerization of alkylene oxide (ethylene oxide, propylene oxide, etc.) to a trivalent alcohol. The addition polymerization of the plurality of types of alkylene oxides may be random addition polymerization or block addition polymerization. Here, as a trivalent alcohol, C3-C10 trivalent alcohol, such as glycerol and a trimethylol propane, is mentioned, for example.
Examples of polyfunctional polyols include tetrafunctional polyols, and specific examples include polyether polyols obtained by addition polymerization of alkylene oxide to ethylenediamine, pentaerythritol, or the like.

  In addition, examples of the polyfunctional polyol include ester-based polyols obtained by condensation of adipic acid and short-chain diols such as ethylene glycol and 1.4-butanediol with polyfunctional triols such as glycerin.

  Since the polyfunctional polyol is bifunctional and does not have an effect of improving compression set, the trifunctional or higher is good, and the compression set becomes better as the number of functional groups increases. However, the number of functional groups is preferably 3 to 4, and the trifunctional polyol is most preferable because the closed cell ratio is increased accordingly.

  A polyfunctional polyol may be used individually by 1 type, and may be used together 2 or more types.

The number average molecular weight Mn of the polyfunctional polyol is preferably 100 to 10,000, and more preferably 400 to 5,000.
It is preferable to set the number average molecular weight Mn of the polyfunctional polyol within the above range because the compression set can be effectively lowered without lowering the toughness (that is, not reducing the elongation) and without increasing the closed cell ratio.

The content of the polyfunctional polyol is preferably 1 to 20 parts by weight and more preferably 2 to 10 parts by weight with respect to PTMG.
When the content of the polyfunctional polyol is in the above range, it is preferable because the compression set can be effectively reduced without suppressing the decrease in elongation and without increasing the closed cell ratio.

(Other additives)
In addition to the above components, the composition for forming the foamed polyurethane material according to this embodiment contains known additives such as antioxidants, colorants, ultraviolet absorbers, inorganic fillers such as calcium carbonate, and the like. Also good.

(Characteristics of polyurethane foam material)
The apparent density of the foamed polyurethane material according to this embodiment is 250 to 500 kg / m ³ , preferably 300 to 450 kg / m ³ . By setting the apparent density of the foamed polyurethane material to 250 kg / m ³ or more, the toughness of the material is increased, and breakage due to impact at the time of hitting is suppressed. By setting the apparent density of the polyurethane foam material to 500 kg / m ³ or less, the weight of the bat is satisfied.

  The closed cell rate of the foamed polyurethane material according to the present embodiment is 0 to 20%, preferably 0 to 5%. By setting the closed cell ratio of the foamed polyurethane material to 0 to 20%, the specific deterioration of the material is suppressed even by repeated hitting. Further, when the foamed polyurethane material is formed, the production becomes easy even with an economical catalyst amount in the molding cycle. That is, it is difficult to shrink after expansion / cooling during demolding, the product dimensions are stable, partial deformation is unlikely to occur, and workability is enhanced.

  The resilience elastic modulus of the polyurethane foam material according to the present embodiment is 50 to 75%, preferably 60 to 70%. By setting the impact resilience of the foamed polyurethane material to 50% or more, the flight distance of the hit ball can be easily extended. As the bat material, the higher the impact resilience, the better. However, a composition exceeding 75% is not preferable because it hardly satisfies the bat standard.

  The compression set of the foamed polyurethane material according to this embodiment is preferably 15% or less, and more preferably 10% or less. By setting the compression set of the foamed polyurethane material to 15% or less, the flight distance of the hit ball can be easily extended.

  The tensile strength of the foamed polyurethane material according to the present embodiment is preferably 1000 kPa or more, more preferably 1500 kPa or more. By setting the tensile strength of the polyurethane foam material to 1000 kPa or more, the toughness of the material is increased, and breakage due to impact at the time of hitting the ball is easily suppressed.

  The tensile elongation of the foamed polyurethane material according to this embodiment is preferably 200% or more, and more preferably 300% or more. By setting the tensile elongation of the foamed polyurethane material to 200% or more, the toughness of the material is increased, and breakage due to impact at the time of hitting the ball is easily suppressed. In addition, by flexibly deforming at the time of ball impact, conversion of kinetic energy into thermal energy is suppressed, and a high rebound resilience can be obtained. The upper limit of tensile elongation is preferably 600% or less from the viewpoint of maintaining the directionality of the hit ball.

  The compression hardness of the polyurethane foam material according to this embodiment is preferably 0.2 to 2.0 MPa, and more preferably 0.4 to 1.0 MPa. When the compression hardness of the foamed polyurethane material satisfies the above range, the toughness of the material is increased, and breakage due to impact at the time of hitting the ball is easily suppressed. In addition, the bottom of the ball does not occur even when the ball is hit.

  In addition, each said characteristic of the foaming polyurethane raw material which concerns on this embodiment is acquired by adjusting the kind and quantity of a component for obtaining a foaming polyurethane raw material.

(Manufacture of polyurethane foam material)
The foamed polyurethane material according to this embodiment can be produced according to a known method. For example, after mixing components other than MDI-based isocyanate, MDI-based isocyanate is mixed with this mixed solution to prepare a urethane raw material solution. Using this urethane raw material liquid, it is poured into a die having a desired shape or a hitting portion of a hitting bat, and then heated. Thereby, a foamed polyurethane material is obtained. Alternatively, the foamed polyurethane material may be attached later to the hitting portion of the hitting bat.

  Examples of the present invention will be described below, but the present invention is not limited to these examples. In the following description, unless otherwise specified, “parts” and “%” relating to blending amounts (contents and addition amounts) are all based on weight.

<Example 1>
The above polyol component preheated to 50 ° C. is precisely weighed in a polycup, and is supplied to “High Speed Emulsification / Dispersing Machine TK Homo Disperser 2.5 Model (DH-2.5 / 1001)” manufactured by PRIMIX Corporation. And stirring at 3000 rpm for 1 minute to prepare a polyol component-containing solution.

-Polyol component-
Main polyol: Polytetramethylene glycol “PTMG3000 (Mitsubishi Chemical Corporation, functional group = 2, Mn = 3000)” 100 parts Trifunctional polyol: Polyether glycol “Sanix GP3000 (Sanyo Chemical Industries, Ltd.) , PO / EO (molar ratio) = 100/0, functional group number f = 3, Mn = 3000) ”3 parts Cell opener: Polyether glycol“ Sanix PL910 (manufactured by Sanyo Chemical Industries, Ltd., PO / EO ( Mole ratio) = 84/16, number of functional groups f = 2, Mn = 900) 5 parts ・ Foam stabilizer: Non-reactive silicone foam stabilizer “DOW CORNING TORAY SZ-1642 (manufactured by Toray Dow Corning Co., Ltd.)” 1 part ・ Catalyst: Amine catalyst “DABCO 33-LV (manufactured by Air Products Japan)” 0.7 part Foams: distilled water 0.8 parts

  Next, 22.7 parts (equivalent to Index = 105) of isocyanate [monomeric MDI “Millionate MT (manufactured by Tosoh Corporation)] preheated to 50 ° C. was added to the resulting polyol component-containing solution. Stir at 5000 rpm for 10 seconds with “High-speed emulsification / dispersing machine TK.

Next, the obtained urethane raw material liquid is a rectangular frame composed of an aluminum frame mold (inner diameter: 180 mm × width: 140 mm × thickness: 10 mm) and a lower plate (thickness: 10 mm) that has been heated to 50 ° C. in advance. A predetermined amount (about 95 g) is put into the depression. After the urethane raw material liquid is charged, the upper lid (made of aluminum, thickness 10 mm) is quickly put on and fixed at four locations with a vise.
In addition, the inside of the aluminum frame mold and the inside of the top lid (urethane raw material liquid contact surface) is coated in advance with a release agent “Rim Rikei N848 (manufactured by Chukyo Yushi Co., Ltd.)” so that it can be peeled off after curing. Warm at 100 ° C. for 30 minutes.

Next, an aluminum container (container made of a frame mold and an upper lid) fixed with a vise is held in an oven at 50 ° C. for 10 minutes, and then removed from the oven and cooled at room temperature for 10 minutes. Thereafter, the vise is removed, the upper lid and the lower plate are taken out, and the foamed polyurethane foam is taken out from the frame mold.
And after confirming the expansion | swelling (shrinkage | contraction) and skin breaking condition of the obtained polyurethane foam foam, it put into 75 degreeC oven for the purpose of reaction completion for 8 hours.

  The intended foamed urethane material was obtained by the above operation.

<Examples 2-28 and Comparative Examples 1-15>
According to Table 1-Table 7, the objective foaming urethane raw material was obtained like Example 1 except having changed the kind and quantity (parts) of the component.

(Evaluation)
While measuring the characteristics of the foamed urethane material obtained in each example, various tests were performed for evaluation.

  Hereinafter, various measurement methods and various tests performed in this example will be described. In addition, the various values of this invention are values measured by the measuring method shown below.

(Measuring method)
-Apparent density-
The apparent density is measured by the following method.
First, a sample to be measured (approximate size: 180 mm long × 140 mm wide × 10 mm thick) is prepared in an environment of 23 ± 3 ° C. Next, the weight of the sample is measured with a precision balance with an accuracy of 1/100 g. Next, using a digital gauge, the thickness of the sample is measured at nine locations with an accuracy of 1/100 mm using a probe having a diameter of 10 mm and a load of about 0.6 N, and an average value is obtained. The vertical dimension and the horizontal dimension of the sample are measured at three locations using a digital caliper, and the average is obtained. The volume of the sample is calculated from the obtained dimensions. Then, the apparent density is obtained by the formula: apparent density = weight / volume.

-Rebound resilience-
The impact resilience is measured according to JIS K 6400 (1997 / A method). For measurement, a sample to be measured (approximate size: length 180 mm × width 140 mm × thickness 10 mm) is stored in an environment of 23 ± 3 ° C. for one day or more. This is performed using “FR-1 type” manufactured by Kobunshi Keiki Co., Ltd. in an environment of 23 ± 3 ° C.

−Tensile strength / elongation−
The tensile strength / elongation is measured according to JIS K 6400-5. Measurement is performed by punching the measurement object into a dumbbell No. 2, obtaining a sample, and using the obtained sample, “Tensilon Universal Material Testing Machine UCT-500” manufactured by Orion Tech Co., Ltd. at a speed of 200 mm / min. Do. And the intensity | strength and elongation at the time of a sample fracture | rupture are measured.

-Closed cell ratio-
The closed cell ratio is measured according to the Beckman method (air comparison specific gravity measurement method: ASTM D 2856-70). Specifically, a sample having a size of 20 mm × 20 mm × thickness mm was cut out from the measurement object, and the volume (cm ³ ) of the obtained sample was measured using BECKMAN-TOSHIBA, LTD. Measured with an “air comparison type hydrometer 930 type” (pressurization method). The measured volume of the sample is taken as the measurement value. On the other hand, the volume was measured in a state where the sample was not put into the “air comparison type hydrometer 930 type”, and a background measurement value (blank value) was obtained. And the closed cell rate (closed cell rate per space volume) Vc (%) is calculated by the following formula.
Formula: Vc (%) = [(ΔV−E) / (V−E)] × 100
ΔV: {(measured value) − (blank value)} (cm ³ )
V: Apparent volume of sample by submersion method (cm ³ )
E: Volume of resin (polyurethane) (cm ³ ) = {(weight of sample) / (true specific gravity of sample)}

-30% compression hardness-
The 30% compression hardness is measured in accordance with JIS K 6400-2 (2012). Specifically, a sample having a size of 20 mm × 20 mm is cut out from the measurement object, and the thickness of the obtained sample is measured. Next, the sample is compressed at a speed of 10 mm / min by using “Tensilon Universal Material Testing Machine UCT-500” manufactured by Orion Tech Co., Ltd. And the stress at the time of 30% compression is measured with respect to the sample thickness, and the measured value is defined as 30% compression hardness.

-30% compression set-
The 30% compression set is measured according to JIS K 6400-4 A method (2004). Specifically, a sample having a size of 20 mm × 20 mm is cut out from the measurement object, and the thickness of the obtained sample is measured. Next, the sample is sandwiched between two stainless plates through a spacer having a thickness corresponding to 70% of the sample thickness, and fixed in a compressed state of 30%. In that state, it is kept in an oven at 70 ° C. for 22 hours. Next, remove the sample from the stainless steel plate out of the oven. Thereafter, the thickness of the sample left at room temperature of 23 ° C. for 30 minutes is measured. Then, a 30% compression set is calculated based on the following formula.
Formula: CS = (t0−t) / t0 × 100
t0: thickness of the sample before compression t: thickness of the sample after compression

-Demolding situation-
After removing the polyurethane foam from the frame mold. The state of demolding of the obtained polyurethane foam was evaluated.
The condition at the time of demolding confirmed the state of expansion (or contraction) and skin breakage of the urethane foam. In addition, odor (isocyanate odor) was also confirmed. In the table, the situation where the urethane foam is excessively expanded (or contracted) is referred to as “expanded (or contracted)”, and the condition where the foamed urethane foam is slightly expanded (or contracted) is “expanded (or contracted)”. The situation of slightly expanding (or contracting) was expressed as “slightly expanding (or slightly contracting)”. In addition, when there was no particular problem at the time of demolding, it was described as “good”.

-Repeated durability test-
A repeated durability test was performed on Example 28 and Comparative Examples 14 to 15.
The repeated endurance test was performed in accordance with a repeated compressive residual strain test “JIS K6400-4 B method (constant displacement method)”. Then, the retention rate of the sample thickness after the test (sample thickness after the test / sample thickness before the test × 100) and the resilience modulus of the sample before and after the test were examined. The conditions of the repeated compression residual strain test are as follows.
・ Sample thickness: 15mm
・ Compression rate: 50%
-Cycle: 60 times / minute-Number of compressions: 80,000 times continuously

  Hereinafter, the measurement results of the physical characteristics of each example and the results of various tests are listed in Tables 1 to 8. In Tables 1 to 8, the notation “←” indicates the same content (or the same value) as the left column.

From the above results, it can be seen that the urethane foam material of the present example has a high apparent density and high rebound resilience, a low closed cell ratio, and is suitable as a urethane foam material for a hit ball bat. It can be seen that the urethane foam material of this example can also reduce compression set (for example, see comparison between Examples 1 to 3 and Example 4). Thereby, it can be seen that the hitting bat using the polyurethane foam material of the present example is not easily torn by impact at the time of hitting and can increase the flight distance of the hit ball even by repeated hitting.
It can also be seen that the foamed urethane material of this example does not cause expansion (or contraction), skin breakage, or the like at the time of demolding, has high workability and is easy to manufacture.

  The details of the abbreviations in the table are as follows.

-Polyol-
PTMG3000: Polytetramethylene glycol “PTMG3000 (manufactured by Mitsubishi Chemical Corporation, functional group number f = 2, Mn = 3000)”
PTMG2000: Polytetramethylene ether glycol “PTMG2000” manufactured by Mitsubishi Chemical Corporation, functional group number f = 2, Mn = 2000) ”
PTMG1000: Polytetramethylene ether glycol “PTMG1000” manufactured by Mitsubishi Chemical Corporation, functional group number f = 2, Mn = 1000) ”
PTMG850: polytetramethylene ether glycol “PTMG850 (Mitsubishi Chemical Corporation, functional group number f = 2, Mn = 850)”

S3011: Polyether polyol “Preminol S3011 (Asahi Glass Co., Ltd., functional group number f = 3, Mn = 10000):
GP3000: Polyether glycol “SANNICS GP3000 (manufactured by Sanyo Chemical Industries, Ltd., PO / EO (molar ratio) = 100/0, number of functional groups f = 3, Mn = 3000)”
GP1500: Polyether glycol “Sanix GP1500 (manufactured by Sanyo Chemical Industries, PO / EO (molar ratio) = 100/0, number of functional groups f = 3, Mn = 1500)”
PP2000: Polyether glycol “Sanix PP2000 (manufactured by Sanyo Chemical Industries, Ltd., PO / EO (molar ratio) = 100/0, number of functional groups f = 2, Mn = 2000)”
PP1000: Polyether glycol “Sanix PP1000 (manufactured by Sanyo Chemical Industries, Ltd., PO / EO (molar ratio) = 100/0, number of functional groups f = 2, Mn = 1000)”

-Functional polyol-
GP3000: Polyether glycol “SANNICS GP3000 (manufactured by Sanyo Chemical Industries, Ltd., PO / EO (molar ratio) = 100/0, number of functional groups f = 3, Mn = 3000)”
S3011: Polyether polyol “Preminol S3011 (Asahi Glass Co., Ltd., functional group number f = 3, Mn = 10000)”
-EP551C: Polyether glycol Actol EP551C (PO / EO = 85/15, functional group number f = 3, MW = 3000) manufactured by Mitsui Chemicals, Inc.
GP400: polyether glycol “Sanix GP1000 (manufactured by Sanyo Chemical Industries, Ltd., PO / EO (molar ratio) = 100/0, number of functional groups f = 3, Mn = 400)
Glycerol: Glycerol (functional group number f = 3)
IR94: Trimethylolpropane ethylene oxide adduct “IR-94”, Mitsui Chemicals, Inc., functional group number f = 3, molecular weight = 183) ”

-Cell opener-
PL910: Polyether glycol “SANNICS PL910 (manufactured by Sanyo Chemical Industries, Ltd., PO / EO (molar ratio) = 84/16, functional group number f = 2, Mn = 900)
PP4000: Polyether glycol “SANNICS PP4000 (manufactured by Sanyo Chemical Industries, Ltd., PO / EO (molar ratio) = 100/0, number of functional groups f = 2, Mn = 4000)”
PP2000: Polyether glycol “Sanix PP2000 (manufactured by Sanyo Chemical Industries, Ltd., PO / EO (molar ratio) = 100/0, number of functional groups f = 2, Mn = 2000)”
PP600: Polyether glycol “Sanix PP600 (manufactured by Sanyo Chemical Industries, Ltd., PO / EO (molar ratio) = 100/0, number of functional groups f = 2, Mn = 600)”
PP400: Polyether glycol “Sanix PP400 (manufactured by Sanyo Chemical Industries, Ltd., PO / EO (molar ratio) = 100/0, number of functional groups f = 2, Mn = 400)”
-DPG: Dipropylene Glycol (dipropylene glycol (terminal secondary alcohol)), manufactured by Wako Pure Chemical Industries, Ltd.-DEG: Diethylene Glycol (diethylene glycol (terminal primary alcohol)), manufactured by Wako Pure Chemical Industries, Ltd.-LV100 : Polybutene “Nisseki Polybutene LV-100 (manufactured by JX Energy Co., Ltd., functional group number f = 0)”
HV15: Polybutene “Nisseki Polybutene HV-15 (manufactured by JX Energy Co., Ltd., functional group number f = 0)
PS32: Liquid paraffin (polyethylene wax) “Diana Process Oil PS32 (manufactured by Idemitsu Kosan Co., Ltd., functional group number f = 0)”
Oxo 900: isononanol “Oxocol 900 (manufactured by KH Neochem, functional group number f = 1, Mn = 142.24)
SPX80N: Polyether acetate ester “Sunfresh SPX-80N (manufactured by Sanyo Chemical Industries, Ltd., functional group number f = 0)
1,4-BD: 1,4-butanediol (terminal primary alcohol, functional group number f = 2, MW = 91) manufactured by BASF Idemitsu Co., Ltd.
80-4000: Sanyo Kasei Kogyo Co., Ltd. polyether glycol Newpol 80-4000 (PO / EO = 20/80, functional group number f = 2, MW = 4000)

-Foam stabilizer-
SZ-1642: Non-reactive silicone foam stabilizer “DOW CORNING TORAY SZ-1642 (manufactured by Dow Corning Toray)”

-Catalyst-
33-LV: Amine catalyst “DABCO 33-LV (manufactured by Air Products Japan)”

-Isocyanate-
・ M-MT: Monomeric MDI “Millionate MT (manufactured by Tosoh Corporation)”
T65: Toluene diisocyanate “Coronate T-65 (manufactured by Tosoh Corporation)”
DC6974: Prepolymer of 4,4-diphenylmethane diisocyanate and polypropylene glycol (isocyanate content 13.1% by weight) “DC6974 (Nippon Polyurethane Co., Ltd.)”

Claims (4)

A cured product of a composition comprising polytetramethylene glycol, diphenylmethane diisocyanate-based isocyanate, a foaming agent, a catalyst, a foam stabilizer, and a cell opener;
A foamed polyurethane material for a hitting ball bat having an apparent density of 250 to 500 kg / m ³ , a closed cell ratio of 0 to 20%, and a rebound resilience of 50 to 75%.   2. The foam for a hitting ball bat according to claim 1, wherein the cell opener is at least one selected from the group consisting of a low molecular diol, a polypropylene glycol-based bifunctional polyol, a polyether acetate ester, a polybutene, and a paraffinic oil. Polyurethane material.   The foamed polyurethane material for a hit ball bat according to claim 2, wherein the polypropylene glycol-based bifunctional polyol is a bifunctional polyol having an ethylene oxide content of 0 to 80 mol% and a number average molecular weight Mn of 400 to 4000.   The foamed polyurethane material for a ball striking bat according to any one of claims 1 to 3, wherein the composition further comprises a polyfunctional polyol having 3 or more functional groups and a 30% compression set is 15% or less.