JPH0638712Y2 - Writing instrument cap - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a cap for a writing instrument.

[Prior art and its problems]

For writing instruments that use water-based ink, if the ink evaporates from the pen when not in use, the ink will run out at the beginning of writing and writing will not be possible, so a pen with a highly airtight cap will be fitted over the writing instrument to cover the pen. I am trying. In other words, the pen body is placed in a sealed space to prevent the ink from drying, but when the cap is fitted, it is pushed in a little further after it becomes airtight, so the pressure inside the cap momentarily becomes high. , Ink adhering to the pen body or ink from the relay core flows back into the writing instrument. For this reason, the ink may run out at the beginning of writing and writing may become impossible. On the contrary, when the cap is removed, the cap is pulled out slightly in the airtight state, so that the inside of the cap is momentarily depressurized, and at this time, the ink is excessively discharged into the cap. Further, when the cap is left in a fitted state, the pressure rises when the inside temperature becomes high, and the ink may flow back into the writing instrument also at this time. That is, various problems occur due to changes in the pressure inside the cap.

[Purpose of device]

Therefore, an object of the present invention is to provide a writing instrument cap that has an ink evaporation preventing function, suppresses pressure change inside the cap, and does not cause excessive ink discharge or ink shortage.

[Constitution of the device and its action]

The writing instrument cap according to the present invention has a ventilation opening formed at the top or the peripheral surface thereof, and the ventilation opening has a pore size of 1 or less.
It is characterized by being covered with a thin film provided with a large number of micropores of up to 60 microns.

That is, the pore size is 1-60 in the thin film that covers the ventilation opening.
Since a large number of micron-sized holes are provided, when the pressure difference between the inside and the outside of the cap exceeds a predetermined value, ventilation is performed through these holes. Therefore, the pressure change inside the cap is suppressed, and the problem caused by the pressure change can be eliminated. Further, since the thin film has a small pore size, the vapor of the water-based ink does not easily pass therethrough, and the function of preventing evaporation of the water-based ink is ensured.

〔Example〕

The present invention will be described in detail below with reference to the embodiments shown in the drawings.

The writing instrument main body 1 is, for example, a ballpoint pen that uses water-based ink, and the water-based ink contained therein is transmitted to the pen body 12 for writing. The cap 2 is fitted to the writing instrument body 1 with good airtightness to cover the pen body 12. A ventilation opening 21 is provided at the top of the cap 2, and the ventilation opening 21 is covered with the thin film 3. The ventilation opening 21 may be provided on the peripheral surface of the cap 2. The thin film 3 is made of, for example, a fluororesin and has a film thickness of about 0.1 to 0.2 mm. The thin film 3 is provided with a large number of micropores having a pore size of 1 to 60 μm. The inside and outside of the cap 2 is ventilated through these micropores, and the thin film 3 acts as a ventilation membrane, but the permeation initiation pressure when the pore size of the micropores is 1 micron (minimum pressure difference between the inside and outside of the cap 2 where ventilation begins). Is about 0.25 kg / cm ² , and if the micropores are smaller than this, the permeation initiation pressure is too large to allow easy ventilation, and the effect of suppressing the pressure change inside and outside the cap 2 is insufficient. Conversely, the pore size of the micropores is 60
The permeation initiation pressure at the time of micron is about 0.01 kg / cm ² ,
If the micropores are larger than this, the permeation initiation pressure is too small, and the vapor of the water-based ink easily passes through the micropores, and it is not possible to ensure a sufficient evaporation prevention function for the water-based ink, and it is left for a long time. The ink attached to the pen body 12 evaporates, and the ink runs out at the beginning of writing.

Then, when the cap 2 is left in a fitted state, the pressure becomes high when the inside temperature becomes high, but when this pressure exceeds the permeation start pressure of the thin film 3, the air in the cap 2 becomes a minute amount of the thin film 3. Since it escapes to the outside through the hole, the pressure in the cap 2 does not become so high, and the ink adhering to the pen body or the ink of the relay core does not flow back into the writing instrument. Further, when the cap 2 is fitted to the writing instrument main body 1, the pressure in the cap 2 increases momentarily as described above, but at this time also, the air in the cap 2 passes through the minute holes of the thin film 3 to the outside. Therefore, the pressure in the cap 2 does not become so high. Conversely, when the cap 2 is removed, the pressure inside the cap 2 is instantaneously reduced, but air enters the cap 2 through the micropores of the thin film 3 and the pressure drop inside the cap 2 is mitigated. Ink will not be discharged excessively into the cap 2. That is, in any case, the pressure change inside the cap 2 is suppressed, and the problem caused by the pressure change can be eliminated. Also, the thin film 3
Since the pore size of the micropores is small, it is difficult for the vapor of the water-based ink to pass through, and the function of preventing evaporation of the water-based ink is secured.

[Effect of device]

As described above, in the writing instrument cap of the present invention, the ventilation opening formed in the cap is covered with a thin film provided with a large number of micropores having a pore size of 1 to 60 microns, so that the pressure difference between the inside and outside of the cap is increased. When the value exceeds a predetermined value, air is ventilated through these minute holes. Therefore, the pressure change inside the cap is suppressed, and excessive ink discharge or ink shortage does not occur. Further, since the pore size of the micropores is small, the water-based ink attached to the pen body does not evaporate even after being left for a long time, and the original function of the cap can be sufficiently ensured.

[Brief description of drawings]

 The drawing is a cross-sectional view of an embodiment of the present invention. 1 ... Writing instrument main body, 12 ... Pen body, 2 ... Cap 21 ... Vent opening, 3 ... Thin film

Claims (1)

[Scope of utility model registration request] 1. A ventilation opening is formed on the top or the peripheral surface,
A writing instrument cap, wherein the ventilation opening is covered with a thin film provided with a large number of micropores having a pore size of 1 to 60 microns.