JPS58138697A - Pen point made of ceramic - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to a ceramic pen nib.

In general, the materials for writing pen nibs are wear-resistant,
It is required to have properties such as excellent corrosion resistance and impact resistance, and good writing characteristics when made into a product. On the other hand, in recent years, with the automation of office equipment, there has been an increase in the use of writing instruments used to create drawings using computer output, and automated drawings used for computer-based design and drafting in various fields such as automobiles, shipbuilding, and architecture. The field of use has expanded and the methods of use have become more diverse, such as writing instruments for machines, writing instruments adapted to high-speed drafting machines, and writing instruments for dot printers, and there is a strong demand for writing instruments with nibs with excellent impact resistance. In particular, writing instruments for dot printers are required to meet strict requirements for impact resistance.

Conventional writing instruments use felt, plastic, stainless steel, etc. for the nib, but these lack some of the properties required for a nib, such as poor wear resistance or corrosion resistance. It wasn't possible.

Recently, a pen nib made of alumina sintered body has been developed and put into practical use, but even though this nib does not have any problems in terms of wear resistance and corrosion resistance, it is used in automated and high-speed drawing machines, for example. When used continuously for long periods of time, such as dot printers, which are necessary for creating output images for office automation, the movement with the paper surface becomes poor, the coefficient of friction increases, and the ink becomes blurred or interrupted. Furthermore, since it has low impact resistance, it is easily damaged and becomes unusable.

The inventors of the present invention have aimed to improve these drawbacks of the pen nibs of conventional writing instruments, meet the various requirements required for the pen nibs, and adapt them to various usages, especially for long-term use in dot printers. As a result of various research conducted to develop a pen nib with extremely excellent writing characteristics, we found that a nib made from a zirconia sintered body containing zirconia with a tetragonal crystal structure was extremely satisfactory. It was found that the present invention was excellent, and based on this knowledge, the present invention was completed.

That is, the present invention provides a ceramic pen nib made of a zirconia sintered body containing zirconia having at least a tetragonal crystal structure.

Writing instruments in which the pen nib of the present invention is used include, for example, vibrator pens used for handwritten general drafting, automatic drafting, pen-written oscillographs, etc.; refillable pens such as drafting drawers, fountain pens, fiber core writing instruments, etc. In addition to writing instruments, the pen nib of the present invention includes needle pens, writing instruments for office automation, etc., and the pen nib of the present invention is provided in various shapes depending on the usage thereof.

Next, the present invention will be explained with reference to the attached drawings. The attached drawings show an example of a writing instrument having a thin tube-shaped pen tip, and FIG. 1 is a sectional view taken along a plane including the shaft of the writing instrument.
FIG. 2 is an enlarged perspective view of the ink guiding rod. In the figure, an ink guide core 2 is inserted into and held by a thin tube-shaped pen tip 1, and the rear end of the core 2 is firmly inserted into the end of the center hole of an ink guide rod 3. The ink guiding rod 3 is formed with an ink groove 4 over its entire length that reaches the center hole, and the ink in the ink chamber 4 is guided through the middle core 4f! It has the function of guiding

In this writing instrument, the core 2 is closer to the tip of the nib.
(Although it protrudes somewhat, it is designed to be able to move in the axial direction within the nib, and when writing, the center moves back due to pressure from above, and the nib receives that pressure and records.)

The pen tip of the present invention is made of a zirconia sintered body. Zirconia has tetragonal, cubic, and monoclinic crystal structures, but in the present invention, zirconia sintered zirconia containing at least zirconia having a tetragonal crystal structure (hereinafter referred to as tetragonal zirconia) is used. Use your body. Preferably, 30 moles or more of tetragonal zirconia is used.

Particularly preferred are all tetragonal zirconia or
Alternatively, it is a zirconia sintered body in which tetragonal zirconia has a molar ratio of 50 or more, and the remainder is zirconia having a cubic crystal structure (hereinafter referred to as cubic zirconia).

In this way, when a zirconia sintered body contains tetragonal zirconia, the crystal structure transforms from a tetragonal system to a monoclinic system when an external force is applied, and the energy required for this transformation is reduced by stress. It works in the direction of alleviating the stress, giving the pen tip high mechanical strength.

It is desirable for a writing instrument nib to have as high impact resistance and mechanical strength as possible, and these properties increase as the proportion of tetragonal zirconia in the zirconia sintered body increases. It is advantageous to use a material with a high abundance of crystalline zirconia.

On the other hand, the coexistence of cubic zirconia in the zirconia sintered body improves thermal stability, so its presence can be said to be desirable to some extent. However, when zirconia with a monoclinic crystal structure (hereinafter referred to as monoclinic zirconia) exists, microcracks are usually generated around it when it transforms from a tetragonal crystal structure, and it is not susceptible to external forces. ° When the micro-cracks are applied, the fracture progresses starting from these micro-cracks, which causes a decrease in mechanical strength. It is preferable to use 10 molti or less.

The amount of tetragonal, cubic, and monoclinic zirconia present in such a zirconia sintered body can be determined, for example, as follows.

In other words, to determine the amount of tetragonal zirconia, first analyze the surface of the polished pen tip with an automatic recording X-ray diffraction device using a Geiger counter, and determine the amount of cubic zirconia (400).
The diffraction patterns of the tetragonal zirconia (004) plane and the tetragonal zirconia (220) plane are recorded on the chart. Next, from this chart, cubic zirconia (400)
The area intensity of the diffraction peak of the surface is determined, and this area intensity is also read from the chart.
7 (“°°) plane? According to the diffraction angle θ, the formula L= (1+ c
os22θ)/5in2θ・co82θ, 24KV, 1
0mA, rate meter time constant 4 seconds, goniometer rotation speed 0.25 degrees/min, chart speed 20m.
This is achieved by selecting /minute.

By the way, this method is a so-called simple method, and strictly speaking, it gives an approximate value of the amount of tetragonal zirconia, but it does not pose any particular problem in real life.

, ``The amount CM (molti) of monoclinic zirconia can also be determined according to the following formula in exactly the same manner as in the case of tetragonal zirconia.

However, D = Diffraction line intensity of tetragonal zirconia (111) plane E: Diffraction line intensity of monoclinic zirconia (111) plane F: Diffraction line intensity of monoclinic zirconia (111) plane Next, used in the present invention The zirconia sintered body is 0.1 to 5
It is preferable to have an average crystal grain size of μ, particularly 0.1 to 1 μ. Having such a dense structure provides even higher impact resistance, and when processed into a pen tip, it makes smoother contact with the paper surface, improving the wettability of the ink to the paper surface and improving the writing quality. There is an advantage. In addition, mechanical strength is improved, so damage during processing is reduced and quality stability is increased.

Further, the zirconia sintered body used in the present invention preferably has a porosity of 2% or less, preferably 1 inch or less. This porosity P (*) is determined according to the following formula.

In this way, if the pen nib is made of a zirconia sintered body with high porosity, the impact resistance will be improved by two layers, and the fine irregularities on the surface of the nib will be reduced to 4k1. Therefore, the slippage between the pen tip and the writing surface is improved significantly, and the phenomenon of marks such as ink and paper remaining on the pen tip is significantly reduced, which is preferable.

Furthermore, the surface of the zirconia sintered body, which is made up of microcrystals and has a small porosity, is extremely easy to polish, resulting in a high quality nib with a smooth surface. ``The zirconia sintered body used in the present invention as described above can be obtained by dissolving a stabilizer such as zirconia or calcia as a solid solution. can be obtained by

When such a stabilizer is used, sintering can be performed at a relatively low temperature, so the crystal grain size can be reduced, and the crystals become denser, resulting in a sintered body with even higher mechanical strength. It has the advantage of being able to obtain in this case,
Ittria is added at a rate of 1 to 5 molti based on the total amount, and calcia is added at a rate of 1 to 9 molty based on the total amount. Moreover, itria and calcia can be used together, but in that case, it is preferable to select them so that the total amount of both is within the range of 2 to 12 moles.

The pen nib of the present invention can be manufactured, for example, as follows.

First, zirconyl oxychloride (ZrO
Cl2) and yttrium chloride (ycz, ) aqueous solution,
Zirconia (Zr05) and Ittria (y2o5)
Prepare a liquid mixture at a molar ratio of 95:5 to 99:1. Next, this is heated to slowly raise the temperature to about 200° C. to remove moisture, and then further heated to about 1000° C. and calcined for several hours. The obtained zirconia-yttria mixed powder was wet-pulverized in a ball mill, and the pulverized product was calcined again at a temperature of about 1000°C and the pulverization operation was repeated to obtain ZrO2-Y2.
A homogeneous solid solution powder of O3 is prepared. Next, a binder such as methyl cellulose or wax is added to the obtained raw material powder and mixed, and the pen tip is formed into a desired shape using an extrusion method.
Heating is performed at a rate of 100 to 100°C up to a temperature of 0°C, and from approximately 1000°C at a rate of 50 to 100°C, and after reaching a temperature of approximately 1600°C, it is held at this temperature for several hours and baked. conclude.

The sintered body is then cooled at a rate of 200 to about 600° C. to about 1000° C., and then furnace cooled from about 100 to about 600° C. to room temperature.

The surface of the zirconia sintered body thus obtained is subjected to barrel processing using a centrifugal barrel processing machine to obtain a pen nib having an extremely smooth surface.

In the above sintering process, the pen tip-shaped molded body is fired at a temperature lower than the above sintering temperature conditions, for example, 1300 to 1400°C, and then heated to 1300 to 1500°C under an argon gas pressure of 2000 to 3000 kf/cd. By using the so-called hot isostatic pressure sintering method (H-P), which involves sintering at a temperature of can be further improved.

The pen tip made from the zirconia sintered body containing at least tetragonal zirconia of the present invention, when subjected to external force, sufficiently transforms the crystal structure from tetragonal to monoclinic at the tip of the stress, The energy required for this transformation acts in the direction of stress relief, so it has excellent mechanical strength, especially impact resistance and toughness, and has a lower free energy of formation than alumina or ceramic pen nibs, so it It has low chemical reactivity, such as, and therefore has excellent corrosion resistance, and also has excellent abrasion resistance and good sliding on the paper surface, and has excellent writing characteristics that keep the initial clear writing state for a long time.

The above-mentioned excellent properties as a pen nib are more pronounced when the average particle diameter of the zirconia sintered body is within the range of 0.1 to 5 μm, and when the porosity is 2% or less.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an example of a writing instrument having a capillary nib;
FIG. 2 is an enlarged perspective view of the ink guiding rod. The code (1) in the figure is a thin tubular nib, (2) is a core, and (3
) is an ink guide rod. Patent applicant: Mitsubishi Pencil Co., Ltd. (1 other person) Agent: Akira Agata

Claims (1)

[Claims] l A ceramic pen nib made of a zirconia sintered body containing zirconia having at least a tetragonal crystal structure. 2. The pen nib according to claim 1, wherein the zirconia sintered body contains 30 moles or more of zirconia having a tetragonal crystal structure.