Printing – Printing members and inkers – Pad inker
Reexamination Certificate
2001-12-21
2004-07-27
Shosho, Callie (Department: 1714)
Printing
Printing members and inkers
Pad inker
C523S160000, C524S088000, C524S196000, C524S357000, C524S558000
Reexamination Certificate
active
06766739
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of printing marks on golf balls with color inks. More particularly, it relates to a golf ball printing method using pad printing process capable of efficient production control as well as to a golf ball having a colorful mark printed by the printing method.
2. Description of the Related Art
In general, a golf ball bears a printed mark of a brand name, logo, symbol, play number or the like on a surface thereof. Typical methods of printing a mark on a golf ball surface are classified into two groups, a pad printing process and a transfer printing process. The pad printing process comprises the steps of: transferring an image formed of an ink contained in an ink fountain to a pad, and pressing the pad against the ball surface to transfer the ink image on the pad to the ball surface. The transfer printing process comprises the step of pressing a transfer foil having an ink layer forming an image against the ball surface to transfer the ink image to the ball surface. Since the pad printing process is capable of accommodating to a small lot production, it is employed more widely than the transfer printing process.
Printing inks for use in golf ball printing are classified by the curing mechanism: one-component ink which is cured through evaporation of solvent therein, and two-component ink which is cured by the reaction between the two components. The two-component ink generally comprises a base resin and a curing agent.
One problem associated with one-component ink is that marks printed with such an ink generally have an insufficient strength, which leads not only to easy peeling or chipping of a printed portion upon iron shot or the like but also to staining of a club face with ink thus peeled off.
On the other hand, a two-component reacting ink is advantageous in that: a printed mark formed from cured ink has good durability due to three-dimensional structure of the cured ink; and the ink component such as base resin or curing agent has an affinity to the ball surface to provide a printed mark having high adhesion to the ball surface. However, two-component reacting inks call for control of the rate of curing reaction, because mixing the base resin with curing agent in the ink fountain causes the curing reaction therein to increase viscosity of the ink therein.
If the curing reaction proceeds so fast that the ink viscosity becomes too high, a transferring an image formed of ink from an ink fountain to a ball surface through a pad becomes difficult. Particularly, the transferability of the ink to dimpled portions of the ball surface lowers and, hence, a resulting printed mark is likely to suffer from blurring and chipping. For this reason, it is a common practice to control the ink viscosity by appropriately adding a solvent to the ink in accordance as the curing reaction of the ink proceeds in the ink fountain. In the event the ink viscosity control relied only upon the dilution of the ink with a solvent becomes impossible, the ink in the ink fountain is replaced with newly prepared ink.
If a sufficient pot life is ensured by the control of the curing reaction of the ink, it is possible to prolong the time interval for ink replacement as well as to decrease variations in the density of the printed mark which may occur depending on the curing reaction.
In these years it is a trend that fashionable golf balls are preferred. Printing colorful marks instead of black marks provides such golf balls. Such colorful marks include chromatically colored marks using pigments, and lustrous metallic marks. Recently, golfers tend to prefer marks having metallic luster. To meet such a demand, the art of forming a mark having metallic luster with an ink containing metal powder has been proposed (refer to Japanese Patent Laid-Open Gazette No. HEI 11-114093 for example).
In the case of an ink blended with a coloring agent containing a metal powder such as copper powder or brass powder, or a metal-containing pigment, however, such a metal component acts as a catalyst in the curing reaction between the base resin and the curing agent thereby facilitating the curing reaction. Accordingly, two-component inks containing metal powder or metal-containing pigments involve a faster increase in viscosity than two-component inks free of metal powder or metal-containing pigment and hence suffer from a difficulty in viscosity control, which raises the problem of a further shortened pot life. The pad printing using ink having a short pot life requires frequent ink replacements, makes the printing process control cumbersome and raises the cost of producing golf balls.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a golf ball printing method capable of efficient control of printing process using two-component reacting ink while ensuring a sufficient pot life.
According to the present invention, a method of printing a mark on a surface of a golf ball comprises a printing process using an ink comprising a resin having a hydroxyl group, an isocyanate, a coloring agent containing a metal, and a &bgr;-diketone.
It is to be noted that the term “mark”, as used herein, is meant to include symbols, letters representing a brand name, an owner's name, or the like, figures, numerals representing a player number or the like, and other indicia.
These and other objects, features and attendant advantages of the present invention will be more fully appreciated from the reading of the following detailed description.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The golf ball printing method of the present invention is characterized by using ink comprising a resin having a hydroxyl group, an isocyanate, a coloring agent containing a metal, and a &bgr;-diketone.
The ink used in the printing method of the present invention is first described.
The resin having a hydroxyl group reacts with the isocyanate to form a film in a printed mark. The resin having a hydroxyl group, hereinafter referred to as “OH-functional resin”, may have at least one hydroxyl group in its polymer chain or at the terminal of its polymer chain. The hydroxyl group may be derived from alcohol, carboxylic acid or epoxy which constitutes the resin. Specific examples of such OH-functional resins include epoxy resin, polyester resin, polyacrylic acid, polyvinyl alcohol, and polyamide resin. Among them, epoxy resin is preferably used because it is excellent in adhesion to a ball surface.
The isocyanate serves as a curing agent for the resin having a hydroxyl group. Specific examples of such an isocyanate include hexamethylene diisocyanate, xylylene diisocyanante, tetramethylxylylene diisocyanante, tolylene diisocyanante, and hydrogenated diphenyl diisocyanante.
The content ratio of the curing agent (i.e. isocyanate) to OH-functional resin is preferably not less than 0.05, more preferably not less than 0.07, much more preferably not less than 0.1. The upper limit of the content ratio (i.e. curing agent/OH-functional resin) is preferably 1.0. If the content ratio is less than 0.05, a resulting mark has lowered durability due to the insufficient three-dimensional structure of the cured resin. If it is more than 1.0, curing proceeds so fast that a sufficient pot life cannot be ensured, resulting in lowered workability.
The &bgr;-diketone forms a chelate with the coloring agent containing a metal or surrounds the coloring agent containing a metal, thereby reducing the frequency of contact between the film-forming components (i.e. the combination of the OH-functional resin and the isocyanate) and the metal-containing coloring agent. Thus, the &bgr;-diketone serves to restrain the curing reaction between the OH-functional resin and the isocyanate from being facilitated by the metal-containing coloring agent.
The &bgr;-diketone preferably has such a low boiling point as to allow easy volatilization thereof. More preferably, the boiling point of the &bgr;-diketone ranges between 130° C. and 160° C. This is because the &bgr;-diketone is contained i
Endo Seiichiro
Isogawa Kazuhiko
Birch & Stewart Kolasch & Birch, LLP
Shosho Callie
Sumitomo Rubber Industries Limited
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