A ballpoint pen is a writing instrument which features a tip that is automatically refreshed with ink. It consists of a precisely formed metal ball seated in a socket below a reservoir of ink. As the pen is moved along a writing surface, ink is delivered. Even though ballpoint pens were first patented in the late nineteenth century, they only started to reach commercial significance in the early 1950s. Now, ballpoint pens dominate the writing instrument market, selling over one hundred million pens each year worldwide.

History

While the idea of a ballpoint pen had been around for many years, it took three different inventors and almost 60 years to develop this modern writing instrument. The first patent for this invention was issued on October 30, 1888, to a man named John J. Loud. His ballpoint pen consisted of a tiny rotating ball bearing that was constantly coated with ink by a reservoir above it. While this invention worked, it was not well suited for paper because it leaked and caused smearing. Two other inventors, Ladislas Biro and his brother Georg, improved on Loud's invention and patented their own version, which became the first commercially significant ballpoint pen. These pens still leaked, but not as badly. They became popular worldwide, reaching the height of sales in 1944. The next year another inventor, Baron Marcel Bich, finally solved the leakage problem and began manufacturing Bic pens in Paris. Over the years, many improvements have been made in the technology and quality of the various parts of the pen, such as the ink, the ball, the reservoir, and the body.

Background

The ballpoint pen was developed as a solution to the problems related to writing with a fountain pen. Fountain pens require the user to constantly refresh the pen by dipping its tip in ink. This is not necessary with a ballpoint pen because it is designed with its own ink reservoir, which uses capillary action to keep the ink from leaking out. At the tip of the pen is a freely rotating ball seated in a socket. Only part of this ball is exposed; the rest of it is on the inside of the pen and is constantly being bathed by ink from the reservoir. Pressing the tip of the pen on the writing surface causes the ball to roll. This rolling action then transfers ink from the inside of the pen to the writing surface.

While different designs of ballpoint pens are available, many of the components are the same. Common components include a ball, a point, ink, an ink reservoir or cartridge, and an outer housing. Some pens are topped with a cap to prevent it from leaking or having its point damaged. Other pens use a retractable point system for the same reason. Here a small spring is attached to the outside of the ink reservoir, and when a button is pushed, the point is either exposed or retracted. Still other varieties of ballpoint pens have multiple ink cartridges, making it possible to write in different colors using one pen. Other pens have refillable ink cartridges. One type of pen has a pressurized cartridge that enables the user to write underwater, over grease, and in space.

Raw Materials

A variety of raw materials are used for making the components of a ballpoint pen, including metals, plastics, and other chemicals. When ballpoint pens were first developed, an ordinary steel ball was used. That ball has since been replaced by a textured tungsten carbide ball. This material is superior because it is particularly resistant to deforming. The ball is designed to be a perfect sphere that can literally grip most any writing surface. Its surface is actually composed of over 50,000 polished surfaces and pits. The pits are connected by a series of channels that are continuous throughout the entire sphere. This design allows the ink to be present on both the surface and interior of the ball.

The points of most ballpoint pens are made out of brass, which is an alloy of copper and zinc. This material is used because of its strength, resistance to corrosion, appealing appearance, and ability to be easily formed. Other parts, like the ink cartridge, the body, or the spring can also be made with brass. Aluminum is also used in some cases to make the pen body, and stainless steel can be used to make pen components. Precious metals such as gold, silver, or platinum are plated onto more expensive pens.

The ink can be specially made by the pen manufacturer. To be useful in a ballpoint pen, the ink must be slightly thick, slow drying in the reservoir, and free of particles. These characteristics ensure that the ink continues to flow to the paper without clogging the ball. When the ink is on the paper, rapid drying occurs via penetration and some evaporation. In an ink formulation, various pigments and dyes are used to provide the color. Other materials, such as lubricants, surfactants, thickeners, and preservatives, are also incorporated. These ingredients are typically dispersed in materials such as oleic acid, castor oil, or a sulfonamide plasticizer.

Plastics have become an important raw material in ballpoint pen manufacture. They have the advantage of being easily formed, lightweight, corrosion resistant, and inexpensive. They are primarily used to form the body of the pen, but are also used to make the ink cartridge, the push button, the cap, and part of the tip. Different kinds of plastics are used, based on their physical characteristics. Thermosetting plastics, like phenolic resins, which remain permanently hard after being formed and cooled, are typically used in constructing the body, cap, and other pieces. Thermoplastic materials remain flexible. These include materials like high-density polyethylene (HDPE) and vinyl resins, which can be used to make most of the pen components.