JPH0247980Y2 - - Google Patents

Description

[Detailed explanation of the idea]

(Industrial Application Field) The present invention relates to golf balls, particularly white golf balls. (Prior Art and Problems Therewith) There are two types of golf balls: one-piece golf balls having a single rubber layer and multi-structure golf balls having an inner core and a cover layer (for example, two-piece golf balls or thread-wound golf balls). These golf balls usually have a white intermediate coat on top of the base coat and are further coated with a clear paint to give them a white appearance. Therefore, the white appearance of golf balls is given by white pigments such as titanium oxide and extender pigments that are added to intermediate coatings, but the reality is that a sufficiently clear whiteness has not yet been achieved. . JP-A-60-40071 discloses a technique for obtaining a clear white color by adding a white pigment and a brightening agent to the cover material of a golf ball itself. However, since the cover material, such as balata or ionomer resin itself does not have a white color, the color of these resins and the white color of the pigment etc. are mixed, and a sufficiently clear white color cannot be obtained. (Purpose of the invention) The object of the invention is to obtain a golf ball with extremely clear whiteness and no discoloration. (Means for Solving the Problems) That is, the present invention provides a golf ball having a white polyurethane coating layer using non-yellowing polyisocyanate containing a fluorescent whitening agent. Conventionally, intermediate polyurethane paints for golf balls usually use polyester preol resin and non-yellowing type polyisocyanate (e.g. toluene diisocyanate), and add a curing reaction catalyst to the resin system with flexibility, modulus, and chemical resistance. ,
It is obtained by adding a slip agent, an extender pigment, and an organic/inorganic pigment and enamelizing it. The whiteness of such paints can be increased by using white pigments such as titanium dioxide and organic/inorganic pigments for toning, but the desired bright whiteness cannot be obtained. In the present invention, the desired clear whiteness is obtained by adding an optical brightener. However, the addition of optical brighteners tends to accelerate yellowing of polyurethane, resulting in poor weather resistance of the golf ball. Therefore,
In the present invention, the problem is improved by using non-yellowing polyisocyanate. As mentioned above, the resin component of the polyurethane paint used in the present invention is produced by the reaction of a non-yellowing type polyisocyanate component and a polyol component.
Examples of non-yellowing type polyisocyanates include hexamethylene diisocyanate, xylene diisocyanate, hydrogenated xylene diisocyanate,
Examples include isophorone diisocyanate, hydrogenated 4,4'-diphenylmethane diisocyanate, and hydrogenated toluene diisocyanate. Preferably hexamethylene diisocyanate. Examples of polyol components that react with polyisocyanate include polyester polyol resins, polyether polyol resins, acrylic polyol resins, phenolic polyol resins, epoxy polyol resins,
Examples include polybutadiene polyol resin. A white polyurethane paint for golf balls is formed by mixing the resin component with conventional solvents, pigments, and other additives. Examples of optical brighteners used in the present invention include:
2,5-bis[5'-t-butylbenzoxazolyl(2)]thiophene (commercially available from Ciba Geigy Japan as Ubitex OB), 7-(2h-naphthol(1,2-d)-triazole-2- Yl)-3-phenyl-kusurin (Leucopure from Sanzos)
Biazoline derivatives (commercially available as Phorwhite K-2002 from Mobay Chemical Co., Ltd.), oxazole derivatives (commercially available as Phorwhite K-2002 from Mobay Chemical Co., Ltd.) and the like (commercially available as Phorwhite K-2002 from Sumitomo Chemical Company) are suitable.
Optical brighteners commercially available as PCS, B) and Hostalux KCB from Hoechst Japan may also be used. The optical brightener is used in an amount of 0.005 to 1.0% by weight, preferably 0.01 to 0.1% by weight, based on the solid content of the white polyurethane paint. If it is less than 0.005% by weight, there will be no sufficient whitening effect, and if it is more than 1.0% by weight, the whitening effect will not increase any further, making it uneconomical. Moreover, if a larger amount is added, the performance of the paint itself, especially the weather resistance, will be adversely affected. The white polyurethane paint of the above formulation may be applied to one-piece golf balls, but it can also be used for multilayer golf balls. For simplicity, the present invention will be described in more detail using the two-piece golf ball shown in FIG. A white polyurethane paint containing a fluorescent whitening agent is applied by a conventional painting method onto the golf ball before the cover layer 2 is applied to the inner core 1 to form a colored layer 3, and then a clear top layer is applied. The uppermost layer 4 may be formed by applying a coating material. Alternatively, the golf ball may be formed by first applying a primer coat, then applying the white polyurethane paint thereon, and then applying a clear top coat. Examples of the primer coat include epoxy primer paint, urethane primer paint, and the like. Examples of the clear top coat include urethane clear paint, acrylic clear paint, and epoxy paint. The present invention will be explained in more detail by way of examples. Example 1 Uvitex OB as a fluorescent whitening agent was added in varying amounts to a white polyurethane paint made of a combination of hexamethylene diisocyanate as a non-yellowing isocyanate and a polyester polyol resin to form a white paint. This paint was applied to a covered two-piece golf ball, and the whitening effect was measured using a Hunter colorimeter. As a control, a sample to which no brightener was added was prepared, and the difference from this control was defined as the whitening effect. The results are shown in Table-1.

[Table] Example 2 A weather resistance test was conducted in the same manner as in Example 1, with different amounts of optical brightener added. Each sample ball was placed on a 45° south-facing slope and left under natural light (sunlight) for two months. The degree of discoloration was visually tested under the following conditions. The results are shown in Table-2.

[Table] ^4. Items with a high degree of discoloration cannot be used, and items with a degree of discoloration of medium or lower cannot be used.
However, it is preferable to use one with minimal yellowing.
Further, the degree of discoloration was tested in the same manner as above using a non-yellowing type polyisocyanate (toluene diisocyanate) instead of the non-yellowing type polyisocyanate. The results are shown in Table-3.

[Table] (Effects of the invention) According to the invention, a golf ball with clear whiteness can be obtained, and it can also be weather resistant, that is, without discoloration.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the golf ball of the present invention. In the figure, 1 is the inner core, 2 is the cover layer, 3 is the colored layer, and 4 is the top layer.

Claims (1)

[Claims for Utility Model Registration] 1. A golf ball having a white polyurethane coating layer using non-yellowing polyisocyanate containing a fluorescent whitening agent. 2. The golf ball according to item 1, wherein the content of the optical brightener is 0.005 to 1.0% by weight based on the solid content of the white polyurethane paint. 3. The golf ball according to item 1, wherein the content of the optical brightener is 0.01 to 0.1% by weight based on the solid white polyurethane paint. 4. The golf ball according to item 1, wherein the non-yellowing polyisocyanate is hexamethylene diisocyanate, isophorone diisocyanate, or a mixture thereof. 5. The golf ball according to item 1, wherein a clear paint is applied on the white polyurethane paint layer.