A sports ball covered in leather.

Abstract

1. A game ball comprising a leather covering secured about a solid core, the leather covering having an inner surface in contact with the solid core and an opposing outer surface, the game ball comprising polyacrylate particles dispersed within, but not encapsulated around, the outer surface of the leather covering.

Description

[Technical Field]

[0001] Cross-reference of related applications This application claims the interests of U.S. Provisional Patent Application No. 63 / 245,964, filed on 20 September 2021, and U.S. Provisional Patent Application No. 63 / 314,493, filed on 28 February 2022, pursuant to Section 119(e) of the U.S. Patent Act. U.S. Provisional Patent Applications No. 63 / 245,964 and No. 63 / 314,493 are incorporated herein by reference.

[0002] The present invention relates to a sports ball, such as a baseball and a softball, which includes a solid core covered with leather. [Background technology]

[0003] Competition balls, covered with new leather, are typically rubbed with a mud-like compound before use to reduce shine and improve grip. This mud treatment process is time-consuming and can yield inconsistent results due to variations in mud composition and treatment techniques. After mud treatment, the ball's outer surface discolors, making it less visible to the batter and more difficult to detect foreign objects (e.g., unauthorized materials used to improve grip).

[0004] Rosin is used by athletes (e.g., weightlifters, rock climbers, baseball players, etc.) to improve hand grip. These materials typically consist of rosin and metal salts (e.g., magnesium chloride) and are applied directly to the hand or glove. Rosin has been shown to improve the coefficient of friction between fingers and a baseball in wet conditions, but its effect is less pronounced in dry conditions. See T. Yamaguchi et al., "Effects of Rosin Powder Application on the Frictional Behavior Between a Finger Pad and Baseball," Frontiers in Sports and Active Living 2:30 (2020). In practice, the improved grip provided by rosin is not durable and needs to be reapplied periodically.

[0005] Polymer coatings are used on golf balls to provide improved weather resistance and / or fluorescence. Such coatings are most commonly used on golf balls, including those with synthetic leather coatings. An example is a polyurethane material coated in multiple layers and cured after application to the outer surface of the golf ball. The resulting coating layer is several mils thick. Similar post-cured polyurethane coatings are also described as protective coatings for golf balls. For example, U.S. Patent No. 5091265 describes the use of a weather-resistant fluorescent coating for golf balls. The composition comprises a two-component polyester polyol resin and a polyisocyanate resin, a fluorescent pigment, and an organic solvent. The coating is applied and cured to form one or more crosslinked layers, each having a thickness of 25 μm to 51 μm (1 mil to 2 mil). The coating may additionally contain crystalline polypropylene to improve grip. The thickness of the crosslinked composition protects the ball (e.g., provides weather resistance) but at the same time wraps around the underlying ball coating. Thus, the texture and feel of the underlying coating are hidden by the crosslinked polyurethane coating.

[0006] The need for a leather-covered sports ball that is durable, has a uniform, predetermined level of grip, does not discolor, and as a result remains very visible to the batter, while also facilitating the detection of foreign objects on the outer surface of the sports ball, remains unmet. [Overview of the project]

[0007] The present invention includes a sports ball having a leather covering fixed around a solid core, the leather covering including an inner surface in contact with the solid core and an outer surface opposite to it. In one aspect of the present invention, the sports ball is characterized by containing polyacrylate particles dispersed on the outer surface of the leather covering but not surrounding it. In another aspect of the present invention, the outer surface of the leather covering is characterized by having a Fourier transform infrared (FTIR) spectrum having peaks corresponding to both leather and polyacrylate. In yet another aspect of the present invention, the outer surface of the leather covering is characterized by having an FTIR spectrum having a peak intensity ratio of 0.10 to 50.0, more preferably 0.25 to 25.0 between the polyacrylate peak and the leather peak. In yet another aspect, the present invention includes a method for producing a sports ball, comprising the steps of: i) obtaining a sports ball having a leather covering fixed around a solid core, the leather covering including an inner surface in contact with the solid core and an outer surface opposite to it; and ii) dispersing polyacrylate particles on the outer surface of the leather covering. Numerous embodiments are described. [Brief explanation of the drawing]

[0008] Various aspects of the present invention can be better understood by referring to the following description in conjunction with the accompanying drawings. These illustrations are for illustrative purposes only and are not intended to be to scale or otherwise limit the present invention. [Figure 1]This is an elevation view showing an embodiment of the present invention, which includes a sports ball (10) having a leather covering (12) including two panels (14) fixed around a solid core (not shown) by sutures (16). [Figure 2] This is a cross-sectional view showing an embodiment of the present invention, which includes a sports ball (10) having a leather covering (12) that includes an inner surface (20) in contact with a spherical solid core (18) and an outer surface (22) on the opposite side. [Modes for carrying out the invention]

[0009] The sports ball of the present invention includes a leather covering fixed around an internal solid core. The core is substantially spherical and preferably includes cork, elastomer (e.g., polycarbonate, polyurethane, polyvinyl chloride, diene rubber, etc.) or a combination thereof, for example, a compressed cork sphere encased in one or more layers of rubber to form a single sphere. The core may optionally be wound with one or more layers of yarn (e.g., wool, polyester, cotton, polyester-cotton blend, etc.) to form a spherical center, which may optionally be covered with one or more elastomer and / or adhesive outer layers to facilitate the attachment of the outer leather covering. Typical leather covering materials include natural leather, such as cowhide and horsehide, for example, full-grain cowhide or horsehide tanned with Grade A alum. In one class of embodiments, the leather covering may be fixed around the core by stitching. For example, two pieces of leather, conventionally pre-cut into a "figure eight" shape, can be stitched together around the core. In the case of a baseball, the stitching typically involves 108 double stitches (hand-stitched) using 10 / 5 red cotton thread lubricated with beeswax. Other threads (e.g., KEVLAR®, polyester, nylon, etc.) and stitching patterns (herringbone pattern) may also be used. Once assembled, the leather covering of a game ball includes an inner surface in contact with the core and an outer surface on the opposite side intended to be handled by the player. As discussed previously, the characteristics of the outer surface of a game ball are important. In particular, the "grip" of the outer surface is crucial for achieving an appropriate level of control during pitching.

[0010] In one embodiment, the subject of the sport is a baseball. While individual leagues may have different requirements, a baseball typically weighs approximately 141 to 149 grams and has a circumference of approximately 22.8 to 23.5 cm. In yet another embodiment, the subject of the sport is a softball. Similar to a baseball, but the core construction is more commonly polyurethane rather than cork wrapped in rubber. A softball typically has a circumference of approximately 30 to 30.8 cm and weighs approximately 177 to 199 grams.

[0011] The subject of this invention is a sports ball characterized by containing polyacrylate particles dispersed on the outer surface of a leather covering, but not surrounding it (i.e., not enveloping it). As used herein, the terms “surrounding” and “enveloping” mean forming a continuous film or barrier on the outer surface (around the periphery) such that the texture of the underlying leather is sealed and no longer provides any tactile sensation. For the purposes of this invention, the polyacrylate particles do not form a continuous coating that completely hides the surface texture of the leather. This is in contrast to leather coatings described in the art, which are typically applied in multiple layers, each more than 1 mil thick. In such known coatings, the “grip” provided by the surface texture of the leather is hidden, and the resulting tactile sensation is determined by the material used for the coating, not by the texture of the leather. In a preferred embodiment of this invention, the aforementioned polyacrylate particles are also dispersed on the stitching used to secure the leather covering around the core of the ball.

[0012] In one embodiment of the class, the outer surface of the leather covering is characterized by having a Fourier transform infrared (FTIR) spectrum with peaks corresponding to both leather and polyacrylate. For leather, 1630 cm⁻¹ -1 From 1655cm -1 The amide carbonyl peak between (1643 cm) -1 ) is a useful identifier. For polyacrylates, 1725 cm-1 ~1740cm -1 Acrylic ester carbonyl peak between (1732cm) -1 ) is a useful identifier. In both cases, the peak intensity is 1505 cm⁻¹ for the spectrum expressed in absorbance units. -1 ~1830cm -1 The baseline is used for calculation. In another embodiment, the peak intensity ratio between the polyacrylate peak and the leather peak is 0.10 to 50.0, more preferably 0.25 to 25.0. FTIR analysis is performed using a Thermo Nicolet iS50 Fourier Transfer Infrared (FTIR) spectrometer with an integrated single-reflection diamond attenuated total reflectance (ATR) accessory, using the following data acquisition parameters.

[0013] [Table 1]

[0014] The sampling method includes i) collecting a background spectrum, ii) pressing the outer surface of the leather coating of a sports ball against an ATR crystal, and iii) measuring the spectrum.

[0015] The polyacrylate particles are preferably uniformly dispersed on the outer surface of the leather covering. In this context, the term “uniformly” means that FTIR peaks for both the leather and the polyacrylate are detectable at at least three, four, preferably six sample locations, each containing a circle with a diameter of 1.5 mm located on the outer surface of the leather covering at equal distances from each other (e.g., top, bottom, front, back, left, and right). In another embodiment, the aforementioned FTIR peak values ​​and peak ratios are based on FTIR analysis using the average of the aforementioned six sample locations.

[0016] In another embodiment, the leather covering (and optionally the thread) of the sports ball includes 10 mg to 150 mg, 10 mg to 100 mg, 20 mg to 90 mg, 30 mg to 80 mg or 40 mg to 70 mg of polyacrylate particles dispersed thereon. The total amount of polyacrylate present can be determined by measuring the difference in weight between the untreated (new) ball and the ball immediately after treatment (i.e., after applying an aqueous emulsion of polyacrylate to the outer surface of the leather covering). This weight difference is then multiplied by the % solids (polyacrylate) of the aqueous emulsion used to treat the ball.

[0017] When dispersed in the amounts indicated above, the subject polyacrylate maintains important aspects of the natural texture of the leather while improving the "grip" by hand of the outer surface of the leather covering. This technical effect avoids excessive grip, such as that which would result in a significant change (e.g., spin rate) from the grip achieved by traditional mud treatment techniques, while providing sufficient grip for the pitcher to have proper control.

[0018] The level of grip can be correlated with the loop tack of the polyacrylate, determined by ASTM D6195-03(2019) Test Method A using an Instron model No.5564 equipped with a 100N load cell. Briefly stated, "loop tack" is the force required to separate the polymer from the surface at the interface immediately after contact under a load equal to only the weight of the polymer and backing for a contact area of 25 mm × 25 mm. This test method involves bringing a loop of the polymer with a backing substrate into controlled contact with a 25 × 25 mm stainless steel surface, and the applied force is only the weight of the loop itself. Then, the polymer is removed from the stainless steel surface, and the maximum force corresponding to the removal of the polymer is measured as the loop tack. For the purposes of this description, a polymer (polyacrylate) of the subject matter of approximately 0.7 mil to 0.8 mil (e.g., approximately 20 grams per square meter (gsm) - dry weight) is coated on one side of a 2 mil, 175 mm PET strip, dried at 80 °C for approximately 5 minutes, and then equilibrated at room temperature (approximately 23 °C) and 50% relative humidity for 60 minutes. In a series of embodiments, the subject polyacrylate, when coated at a thickness of 0.5 mil to 1 mil, more preferably 0.7 mil to 0.8 mil, has an average loop tack value (average of at least 3 test measurements) of less than 300 g, 200 g, and even 100 g. These loop tack values are much lower than those of conventional polyacrylate pressure-sensitive adhesives, which have loop tack values exceeding 500 grams when measured under the same test conditions.

[0019] The level of grip may correlate with the coefficient of friction (COF) of the outer surface of the leather covering. The COF of the leather used to assemble the ball can be determined by measuring the friction between the outer surface of the leather and a rubber probe mounted on a balance arm assembly that measures the force required to move the rubber probe across the outer surface of the leather. The test speed is set to 600 mm / min. The measurement distance is pre-programmed to 40 mm. After the measurement is complete, the coefficient of friction is calculated using an analytical tool. The test is performed using a Dia-Stron® Model No. MTT175 Miniature Tensile Tester, used in conjunction with a Universal Control Unit Model UV1000 and UvWin® software. The rubber probe (product code 176.0699) can be purchased from Dia-Stron. Leather samples are tested in a controlled environment, i.e., room temperature (approximately 23°C) and approximately 50% relative humidity. In one class of embodiments, the COF of leather undergoes a change of less than 50%, 45%, or even 40% as a result of the application of the subject polyacrylate particles. In another embodiment, the COF of leather increases by 5% to 40% as a result of the application of the subject polyacrylate particles. This greatly ensures that the ball retains the COF of untreated (i.e., without polyacrylate) leather. In context, the outer surface of an untreated leather coating has a COF of approximately 0.33, while in one class of embodiments, a treated (i.e., containing the subject polyacrylate particles) leather coating has a COF of 0.20 to 0.60, 0.25 to 0.55, or even 0.30 to 0.50. In another class of embodiments, the outer surface of a leather covering containing polyacrylate particles dispersed thereon has a COF of less than 1.00, 0.90, 0.80, 0.70, 0.60, 0.55, or even 0.5 (based on the average using at least three measurements).

[0020] In another embodiment, the polyacrylate of the subject has a dynamic shear storage modulus (G') greater than 0.1 MPa, greater than 0.5 MPa, or greater than 1.0 MPa (e.g., 0.1 MPa to 15 MPa, 0.5 MPa to 12 MPa, or 1 MPa to 10 MPa) when measured at room temperature. The dynamic shear storage modulus measurement is performed on a TA Instruments ARES-G2 rheometer equipped with an air-cooling accessory (ACS-3) using an 8 mm diameter aluminum disposable plate fixture. Using the dynamic temperature gradient mode, the sample is tested from 160°C to -80°C at a cooling rate of 2° / min with an applied frequency of 6.28 rad / s. The AutoStrain option should be used to ensure that the test remains in a linear viscoelastic regime, with an initial strain of 0.5% and a maximum strain limit of 5%. The fixture is zeroed at the initial test temperature of 160°C. The thickness of the sample can be measured using the instrument's micrometer after the sample is loaded between parallel plates. The test is started after equilibration at 160°C for approximately 10 to 15 minutes. The test sample may be provided as an aqueous emulsion. Pour each emulsion into a ChemWare® Petri dish and dry in a convection hood for several days. Then, invert the resulting coating and expose the bottom surface to air. Dry ice may be used to smoothly remove the coating from the Petri dish. Then, return the inverted coating to the convection hood and leave for several more days. Then, until the time of the test, place the dish with the coating under vacuum at ambient temperature.

[0021] Polyacrylate may be dispersed on the outer surface of the leather covering (and optionally the thread used to sew the covering) before assembling the ball, but preferably the polyacrylate is applied after the ball is assembled, for example, after the leather covering is sewn around the core. The polyacrylate is preferably applied as an aqueous emulsion. Techniques for applying the emulsion are not particularly limited and include spraying techniques (e.g., air spraying, air-assisted spraying, aerosol spraying, high-volume low-pressure spraying, etc.), dipping, padding, tumble drum coating, and brushing. In another embodiment, a relatively dilute aqueous emulsion, for example, with a solid content of 3% to 15%, is used, compared to the 20% to 30% solid content used in conventional leather treatments (e.g., leather furniture, leather seats for automobiles, etc.). Where used herein, the term "% solid content" refers to the non-volatile components of the emulsion. Volatile components volatilize under ambient temperature and standard pressure conditions. Examples of volatile components include organic solvents, water, and ammonia. The emulsion may be applied to the outer surface of the leather covering in one or more sequential applications. After the emulsion is applied, it may be dried at a high temperature, for example, 165°C to 195°C for approximately 30 to 180 seconds. Examples of drying processes include air drying and infrared heating. If the emulsion is applied in several application steps, it is preferably dried before subsequent applications.

[0022] Unlike many traditional leather treatments, the polyacrylate of the subject is substantially reacted before being applied to the ball. That is, the polyacrylate does not form chemical bonds with the outer surface or stitching of the leather coating. In addition, the aqueous emulsion of the subject containing the polyacrylate is preferably free of organic solvents.

[0023] A typical class of polyacrylates includes repeating units represented by formula I.

[0024] [ka] In the formula, R1 is independently selected from hydrogen and methyl (preferably hydrogen), and R2 is independently selected from hydrogen and alkyl groups having 1 to 24 carbon atoms. Such polymers include homopolymers, copolymers, and blends, as well as so-called "core-shell" polymers prepared by well-known multi-stage emulsion polymerization processes. The applicable polymer is preferably predominantly composed of repeating units represented by formula I, i.e., at least 50%, 60%, 70%, 80%, 90%, 95%, and even 99% by weight of the total repeating units. The polymer of the subject may initially be provided as an aqueous emulsion before being applied to the leather of a sports ball. In one class of embodiments, the emulsion contains polyacrylate having an average volume particle (droplet) size distribution (Dv50) of 50 nm to 1000 nm, 80 nm to 500 nm, or 90 nm to 300 nm, as measured by laser diffraction technique using a Mastersizer 3000 (a division of Malvern Panalytical-Spectris (Egham, Surrey, UK)) with a Hydro SV attachment. The term "Dv" represents the average volume particle size of the dispersed particles. Dv50 is the particle size measured at a volume corresponding to 50% of the cumulative particle population. Within this particle size range, the particles do not penetrate the pores of the leather and are mainly maintained on the surface of the leather.

[0025] The polyacrylate of the subject preferably has a weight-average molecular weight (Mw) of 10,000 to 12,000,000, 50,000 to 5,000,000, more preferably 500,000 to 1,500,000 (Daltons), as determined by gel permeation chromatography (GPC). More specifically, GPC separation may be carried out using an Agilent 1260 system consisting of a pump, degasser, autosampler, and Wyatt T-rEX refractive index (RI) detector, operated at 35°C. The system preferably has a column set consisting of two Shodex KF-806L columns (8 mm inner diameter × 300 mm length), and the temperature is maintained at 35°C. A mobile phase of tetrahydrofuran (THF) / formic acid (FA) in a ratio of 100:5 is flowed at a rate of 1 mL / min. The sample was prepared at 2 mg / mL in THF / FA, shaken at room temperature for several hours until completely dissolved, and then filtered before analysis (using a 0.45 μm PTFE w / GMF filter). The sample injection volume was 100 μL, and the run length was 30 minutes. The column was calibrated using a set of narrow polystyrene (PS) standards (EasiCal PS-1) purchased from Agilent. System control, data acquisition, and processing were performed using Wyatt's Astra software.

[0026] In another embodiment, the subject polyacrylate has a glass transition temperature (Tg) of less than 20°C, more preferably less than 10°C, and even more preferably less than 0°C, as determined by dynamic mechanical analysis (DMA). The DMA measurement is performed on a TA Instruments ARES-G2 rheometer equipped with an air-cooling accessory (ACS-3) using an aluminum disposable plate fixture with a diameter of 8 mm. Using the dynamic temperature ramp mode, the sample is tested from 160°C to -80°C at a cooling rate of 2°C / min using an applied frequency of 6.28 rad / sec. To test with an initial strain of 0.5% and a maximum strain limit of 5%, the AutoStrain option is used to ensure that the test remains within the linear viscoelastic regime. The fixture is zero-adjusted at an initial test temperature of 160°C. The thickness of the sample is measured using the instrument's micrometer after loading the sample between the parallel plates. The test is started after equilibration at 160°C for approximately 10 to 15 minutes. The dynamic storage modulus and the dynamic loss modulus (G' and G", respectively) are recorded as a function of temperature for each sample, together with tanδ (= G" / G'). δTg is determined as the peak temperature from tanδ. For multi-stage polymers and blends, the "polymer" may exhibit multiple glass transition temperatures corresponding to each polymer component. For example, in the case of a classical two-stage polymer, the first stage (core) may include a relatively soft polymer having a Tg of -70°C to 10°C (more preferably -45°C to 10°C) and may constitute more than 50% by weight of the total weight of the multi-stage polymer, and includes a relatively hard polymer having a Tg of 20°C to 150°C and constituting less than 50% by weight of the total weight of the multi-stage polymer, for example 5% to 25% by weight of the total weight of the multi-stage polymer for the second stage (shell). For the purposes of multi-stage polymers and blends, the Tg may be expressed as a weighted value based on the relative weights of each of the individual polymer components (i.e., each of the individual polymer segments and / or blend components). For copolymer components, the weighted average Tg is given by the well-known Fox equation: 1 / T g = w1 / T g(1) + w2 / T g(2)This can be calculated using the formula where w1 and w2 refer to the weight fractions of the two comonomers, T g(1) and T g(2) This refers to the glass transition temperature (Kelvin) of two corresponding homopolymers. For polymers containing three or more monomers, an additional section is added (w n / T g(n) If no actual measured Tg value is available, the Tg of the polymer phase can be calculated by using the glass transition temperature values ​​of homopolymers reported in the literature, for example, in Polymer Handbook, 4th edition, edited by J. Brandrup, E. H. Mimmergut and E. A. Grulke, John Wiley and Sons, New York. Thus, the polyacrylate of the subject may contain one or more polyacrylate components. When multiple components are present, the glass transition temperature (Tg) of the polyacrylate components constituting more than 50% by weight, 60% by weight, and in some embodiments 75% by weight of the total weight of the polyacrylate is less than 20°C, less than 10°C, and in some embodiments less than 0°C.

[0027] Applicable polyacrylates are classically derived from the polymerization (e.g., free radical polymerization) of monoethylene unsaturated organic monomers and, optionally, polyethylene unsaturated organic monomers. See, for example, U.S. Patents 7,323,500 and 1,0100,377. As used herein, (i) the term “monoethylene unsaturated organic monomer” (preferably α-monoethylene unsaturated monomer) refers to a compound containing a single polymerizable carbon-carbon double bond that is readily subjected to free radical polymerization under suitable reaction conditions, and (ii) the term “polyethylene unsaturated organic monomer” refers to a compound containing at least two polymerizable carbon-carbon double bonds that is readily subjected to free radical polymerization under suitable reaction conditions. Also as used herein, the use of the term “(meth)” followed by another term such as acrylate refers to both acrylates and methacrylates. For example, the term "(meth)acrylate" refers to either acrylate or methacrylate, the term "(meth)acrylic" refers to either acrylic or methacrylic, and the term "(meth)acrylamide" refers to either acrylamide or methacrylamide.

[0028] Suitable examples of ethylenically unsaturated monomers include (meth)acrylates, for example, C1-C 24 Examples include alkyl (meth)acrylates, hydroxyalkyl (meth)acrylates, and ionic (meth)acrylates, such as acid-containing (meth)acrylates, amine-containing (meth)acrylates, and amide-containing (meth)acrylates. Preferred C1-C 24Examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate. Preferred hydroxyalkyl (meth)acrylates include hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate. Other suitable examples of ethylenically unsaturated monomers include acid-containing monomers, such as (meth)acrylic acid and phosphoethyl (meth)acrylate; difunctional acids, such as itaconic acid; maleic acid; and anhydrides such as maleic anhydride, which form an acid in the presence of water. Other suitable ethylenically unsaturated monomers include styrene; substituted styrenes, such as alpha-methylstyrene; vinyl acetate or other vinyl esters; vinyl monomers, such as vinyl chloride, vinylidene chloride, N-vinylpyrrolidone; and (meth)acrylonitrile. Other suitable ethylenically unsaturated monomers include polyethylenically unsaturated monomers such as allyl (meth)acrylate, diallyl phthalate, 1,4-butylene glycol di(meth)acrylate, 1,2-ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and divinylbenzene; and crosslinkable monomers such as methylol (meth)acrylamide, acetacetate monomer, and acetacetamide monomer. Examples of acetacetate monomers include vinyl acetacetate, acetacetoxyethyl (meth)acrylate, acetacetoxypropyl (meth)acrylate, allyl acetacetate, acetacetoxybutyl (meth)acrylate, and 2,3-di)acetacetoxy)propyl (meth)acrylate. Examples of acetacetamide monomers include vinyl acetacetamide and acetacetoxyethyl (meth)acrylamide.

[0029] As described above, applicable polyacrylates can be prepared using conventional aqueous emulsion polymerization processes. In such emulsion polymerization processes, conventional surfactants, such as anionic and / or nonionic emulsifiers, may be used, for example, alkali metal salts or ammonium salts of alkyl sulfates, alkyl sulfonic acids, fatty acids, and oxyethylated alkylphenols. The amount of surfactant used is usually in the range of 0.1% to 6% by weight, based on the weight of the monomer. Either a thermal initiation process or a redox initiation process may be used. The monomer mixture may be added neat or as an emulsion in water. The monomer mixture may be added in one or more additions or continuously over the allocated reaction period. Conventional thermal free radical initiators that can be used include hydrogen peroxide, sodium peroxide, potassium peroxide, t-butyl hydroperoxide, cumene hydroperoxide, ammonium and / or alkali metal persulfates, sodium perborate, superphosphate and its salts, potassium permanganate, and ammonium or alkali metal salts of peroxydisulfate. These initiators are typically used at levels of 0.01% to 3.0% by weight, based on the total weight of the organic monomers. Usable redox initiators typically include oxidizing agents + reducing agents in combination effective for generating free radicals, including the same free radical initiators listed above as oxidizing agents; as well as suitable reducing agents, e.g., sodium sulfoxylate formaldehyde, ascorbic acid, isoascorbic acid, alkali metal salts and ammonium salts of sulfur-containing acids, e.g., sodium sulfite, sodium bisulfite, sodium thiosulfite, sodium hydrosulfite, sodium sulfide, sodium hydrosulfide or sodium dithionite, sodium formamidine sulfinate, sodium hydroxymethanesulfonate, sodium acetone bisulfite; amines, e.g., ethanolamine, glycolic acid, glyoxylic acid hydrate, lactic acid, glyceric acid, malic acid, tartaric acid, and salts of the aforementioned acids that may be used. Metal salts of iron, copper, manganese, silver, platinum, vanadium, nickel, chromium, palladium, or cobalt may be optionally used to catalyze the redox reaction.The initiator or initiator system may be added sequentially, linearly, or otherwise, in one or more additions over the reaction period, or as a combination thereof. Several azotype organic free radical initiators can be used in the monomer swelling process, such as azobis-isobutyronitrile and azobispropionitrile. A chain transfer agent, such as a mercaptan, may be used to reduce the molecular weight of the polymer.

[0030] Emulsion polymerization may be carried out in a single polymerization step, or as a multi-stage polymerization process in which two or more polymer stages with different compositions are successively prepared. Polymerization techniques used to prepare such aqueous multi-stage polymer particles are well known in the art, for example, in U.S. Patents 4,325,856, 4,654,397, 4,814,373, 5,723,182, 7,323,500, and 1,0100,377.

[0031] Numerous embodiments of the present invention are described, and in some examples, certain embodiments, selections, scopes, components, or other features are characterized as “preferred.” Such designations of “preferred” features should not be construed as essential or important aspects of the present invention. The expressed scope includes the specifically designated endpoints. [Examples]

[0032] Unless otherwise specified, all preparations and tests were carried out at room temperature (RT) at standard pressure (1 atm or 760 mmHg) using the test methods described above.

[0033] Example 1: A monomer emulsion was prepared by mixing deionized (DI, 29 parts) water, an anionic surfactant (sodium lauryl sulfate, 2 parts), ethyl acrylate (EA, 94 parts), and acrylic acid (AA, 4 parts). DI water (118 parts) was added to a four-necked round-bottom flask equipped with a paddle-type stirring rod, thermometer, nitrogen inlet, and reflux condenser. The monomer emulsion was then added to the flask and the reaction was initiated using a redox pair (ammonium persulfate and sulfite reducing agent). The temperature was controlled to below 96°C. After the reaction was complete, the batch was held at that temperature for 15 minutes and then cooled to 60°C. During cooling, the redox pair (t-butyl hydroperoxide and sulfite reducing agent) was added to reduce the residual monomer, and the batch was neutralized to pH 7.5 using ammonia (30% aqueous solution) and 1.8 parts zinc oxide. The particle size was approximately 80 nm. The Tg (transition time) was calculated using the Fox formula and was approximately -19°C. The emulsion had a solid content of 35%.

[0034] Example 2: A monomer emulsion was prepared by mixing deionized (DI, 29 parts) water, an anionic surfactant (sodium lauryl sulfate, 2 parts), butyl acrylate (butyl acrylate, BA, 40 parts), ethyl acrylate (EA, 54 parts), and acrylic acid (MAA, 6 parts). DI water (118 parts) was added to a four-necked round-bottom flask equipped with a paddle-type stirring rod, thermometer, nitrogen inlet, and reflux condenser. The monomer emulsion was then added to the flask and the reaction was initiated using a redox pair (ammonium persulfate and sulfite reducing agent). The temperature was controlled to below 97°C. After the reaction was complete, the batch was held at that temperature for 15 minutes and then cooled to 60°C. During cooling, the redox pair (t-butyl hydroperoxide and sulfite reducing agent) was added to reduce the residual monomer, and the batch was neutralized to pH 7.5 using ammonia (30% aqueous solution) and 2.7 parts zinc oxide. The particle size was approximately 80 nm. The Tg (transition time) was calculated using the Fox formula and was approximately -32°C. The emulsion had a solid content of 34%.

[0035] Example 3: A monomer emulsion was prepared by mixing deionized (DI, 26 parts) water, anionic surfactants (sodium lauryl sulfate and sodium dodecylbenzenesulfonate, totaling 1.5 parts), butyl acrylate (BA, 77 parts), and methacrylic acid (MAA, 3 parts). DI water (97 parts) was added to a four-necked round-bottom flask equipped with a paddle-type stirring rod, thermometer, nitrogen inlet, and reflux condenser. The monomer emulsion was then added to the flask, and simultaneously, an aqueous redox initiator pair (ammonium persulfate and sulfite reducing agent) was added separately. The temperature was controlled to below 88°C by adjusting the feed rate. After the reaction was complete, the batch was cooled to 64°C, and then MMA (20 parts) was added along with another part of the aqueous redox initiator pair. The batch was reacted, held for 15 minutes, and then cooled. During cooling, a redox pair (t-butyl hydroperoxide and sulfite reducing agent) was added to reduce the residual monomer, and the batch was neutralized to pH 7.5 using triethylamine. The particle size was approximately 105 nm. The Tg values, calculated using the Fox formula, were approximately -49.6°C (core) and 105°C (shell). The emulsion had a solid content of 36%.

[0036] Example 4: Pressure-sensitive adhesive A polyacrylate emulsion based on 98% by weight of butyl acrylate monomer and 2% by weight of methacrylic acid was prepared as described in Example 2, Sample 2 of U.S. Patent No. 3,740,366. The particle size was approximately 381 nm. The Tg was approximately -52°C, calculated by the Fox formula.

[0037] [Table 2] * Average value based on 5 measurements. The loop tack of PET without polyacrylate was approximately 22g.

[0038] Example 5: Leather samples used to produce coatings for sports balls were tested, and the coefficient of friction (COF) was determined according to the methodology described above. Measurements were performed on untreated control samples along with leather samples treated with polyacrylate particles from Examples 1-4. This treatment involved spraying each of the aqueous emulsions (5% solids) of the polyacrylates described in Examples 1-4. Two consecutive spray treatments were applied, resulting in approximately 110 mg / ft per sample. 2 The total dry solids content loading level was achieved. The treated samples were dried at 185°C for 2 minutes between each spray application. The test results are shown in the table below.

[0039] [Table 3]

[0040] Example 6: New (untreated) sports balls were treated by spraying them with the aqueous emulsion (5% solids) of Example 3. Four consecutive spray treatments were applied to the sample sports balls to achieve a total dry solids content loading level of approximately 50 mg to 60 mg per ball. The treated samples were dried at 185°C for 2 minutes between each spray application. Next, the samples were subjected to FTIR analysis using four equidistant sample positions per ball according to the method described above. A leather peak of -0.011 (standard deviation 0.006) was observed at 1643 cm². -1 ) Intensity and polyacrylate peak (1732cm²) of -0.130 (standard deviation 0.060) -1 Intensities were observed.

Claims

1. A sports ball comprising a leather covering fixed around a solid core, wherein the leather covering includes an inner surface in contact with the solid core and an outer surface on the opposite side, The leather covering is characterized by containing polyacrylate particles that are dispersed on the outer surface but do not surround it. The outer surface of the leather covering is characterized by having a Fourier transform infrared (FTIR) spectrum with peaks corresponding to leather and polyacrylate. A competition ball with a peak intensity ratio between the polyacrylate peak and the leather peak of 0.10 to 50.

0.

2. The sports ball according to claim 1, wherein the leather covering contains 10 mg to 150 mg of polyacrylate particles dispersed thereon.

3. The sports ball according to claim 1, wherein the leather covering contains 10 mg to 100 mg of polyacrylate particles dispersed thereon.

4. The sports ball according to claim 1, characterized in that the outer surface of the leather covering has a coefficient of friction (COF) of less than 1.

5. The sports ball according to claim 1, wherein the polyacrylate contains one or more polyacrylate components, and the glass transition temperature (Tg) of the polyacrylate components constituting more than 50% by weight of the total weight of the polyacrylate is less than 20°C.

6. The sports ball according to claim 1, wherein the polyacrylate particles have an average volume particle size distribution (Dv50) of 80 nm to 500 nm.

7. The sports ball according to claim 1, wherein the polyacrylate has a dynamic shear storage modulus (G') greater than 0.5 MPa when measured at room temperature.

8. The competition ball according to claim 1, wherein the polyacrylate has a loop tack of less than 200 g.

9. The sports ball according to claim 1, wherein the polyacrylate particles have a weight-average molecular weight (Mw) of 10,000 to 12,000,000.

10. The polyacrylate particles include a polyacrylate containing repeating units represented by formula I, 【Chemistry 1】 In the formula, R １ R is independently selected from hydrogen and methyl, ２ These are independently selected from hydrogen and alkyl groups having 1 to 24 carbon atoms. The competition ball according to claim 1.

11. A method for handling a game ball, i) A step of obtaining a sports ball including a leather covering fixed around a solid core, wherein the leather covering includes an inner surface in contact with the solid core and an outer surface on the opposite side, and ii) A step of dispersing polyacrylate particles on the outer surface of the leather covering. Includes A method wherein the polyacrylate particles are dispersed on the outer surface of the leather coating such that the leather coating has a Fourier transform infrared (FTIR) spectrum having peaks corresponding to both leather and polyacrylate, and the peak intensity ratio between the polyacrylate peak and the leather peak is 0.10 to 50.

0.

12. A sports ball comprising a leather covering fixed around a solid core, wherein the leather covering comprises an inner surface in contact with the solid core and an outer surface opposite to it, and is characterized in that it contains polyacrylate particles dispersed on the outer surface of the leather covering but not surrounding it, and the leather covering contains 10 mg to 150 mg of polyacrylate particles dispersed thereon.

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