JP4192390B2 - Ballpoint pen tip sealing member - Google Patents

Description

【００１８】
以上、詳細に説明したように、本発明のボールペン用ペン先封止部材は、重量減少率が１０％以下の場合は、長期間の経時後でもインキ吐出量が低下せず、線飛びやカスレが極力抑制された筆跡を保つ。[0001]
BACKGROUND OF THE INVENTION
The present invention provides a ballpoint pen tip seal capable of contacting an ink penetrating tip of the ballpoint pen tip nib disposed at the tip of a writing instrument body containing ink containing at least an organic solvent and closing the ink passage hole of the ballpoint pen tip nib. This relates to the member.
[0002]
[Prior art]
Ballpoint pens are used in many cases because they provide a relatively thin handwriting, and unlike writing instruments that have a fiber nib or resin nib, there is little change in the width of the nib due to wear of the nib even when used for a long time. Has been. The ballpoint pen ink includes a so-called oil-based ballpoint pen ink using only an organic solvent and a water-based ballpoint pen ink. Even in the case of water-based ballpoint pen ink, an organic solvent is often added for the purpose of preventing drying of ink at the tip of the pen. The ballpoint pen uses a so-called ballpoint pen tip in which a ball as a writing member is held in a state where the tip part protrudes from the ink passage hole of the ball holder, and the ink attached to the ball surface through the ink passage hole is used. Since the ball is rotated and transferred onto a writing surface such as paper, the gap between the ball and the ball holder that holds the ball is formed as an opening portion of the ink hole. However, the ink may leak from the gaps to stain the paper surface, or air may enter the ball holder and the ink around the ball may dry out, causing ink to cease and the handwriting to be blurred. In order to prevent such a problem, means for closing the gap of the ball-point pen tip with a rubber-like elastic sealing member or the like disposed in the cap when not writing is employed. Such a sealing member is required to have flexibility and restorability of the material from the point that adhesion to the holder member of the chip is required, and also needs non-reactivity with ink and solvent resistance. Silicone rubber, butyl rubber, nitrile rubber, ethylene / propylene rubber, etc. are used.
[0003]
[Problems to be solved by the invention]
In the case where the rubber-like elastic body as described above is used as a ballpoint pen tip sealing member, in a ballpoint pen using an ink containing an organic solvent, a phenomenon may occur in which the ink discharge amount is reduced or the handwriting is faded. there were.
This is because, when “rubber” is used as the ballpoint pen tip sealing member, the plasticizer mixed in the rubber, the remaining vulcanizing agent, or the reaction at the time of vulcanization is brought into contact with the ink. Substances generated in the ink are dissolved in the ink by the organic solvent of the ink, block the ink through holes, increase the viscosity of the ink in the chip by acting on the ink, and deteriorate the ink flow in the ballpoint pen chip. This is probably because of this.
[0004]
[Means for Solving the Problems]
The present invention provides a ballpoint pen tip seal capable of contacting an ink penetrating tip of the ballpoint pen tip nib disposed at the tip of a writing instrument body containing ink containing at least an organic solvent and closing the ink passage hole of the ballpoint pen tip nib. In the member, the material of the ballpoint pen tip pen sealing member is a nitrile rubber compounding composition, and a sample of the nitrile rubber compounding composition is weighed at room temperature and 10 times the weight of the sample in a container that can be sealed. After being immersed in ethanol, sealed and allowed to stand at 50 ° C. for 1 week, taken out from the immersion and left at 50 ° C. for 24 hours to remove ethanol, left to reach room temperature, and weighed again. The gist is a ballpoint pen tip sealing member whose weight reduction rate of the sample in the front and back weighing is 10% or less .
[0005]
Details will be described below.
The ballpoint pen tip nib sealing member of the present invention may have any shape such as a dish shape or a spherical shape as long as the ink penetrating hole of the ballpoint pen tip nib can be closed. Further, the pen tip sealing member may be disposed in the inner hole of the cap, or may be configured to be directly locked to the pen tip.
[0006]
The material of the ballpoint pen tip pen sealing member is rubber such as rubber, elastic rubber, such as silicone rubber, butyl rubber, nitrile rubber, ethylene / propylene rubber, styrene, olefin, urethane, ester, vinyl chloride And various thermoplastic elastomers.
[0007]
For example, nitrile rubber is obtained by vulcanizing a copolymer of butadiene and acrylonitrile with a vulcanizing agent such as sulfur or a sulfur compound, but if there is a large amount of acrylonitrile, it is excellent in oil resistance and mechanical strength and comes into contact with oil-based ink. In this case, deformation due to swelling is eliminated, but on the other hand, the elongation and elasticity are lowered, and the adhesion to the ballpoint pen tip tends to be deteriorated. Therefore, in order to adjust the balance between oil resistance and appropriate hardness, reinforcing agents, plasticizers and the like are added. Reinforcing agents are added to improve the tensile strength, modulus, hardness, elasticity, friction resistance, tear resistance, etc. of rubber. Carbon black, zinc oxide, calcium carbonate, fine powder silica, clay, diatomaceous earth, talc , Mica and barium sulfate. Plasticizers are added to swell and depolymerize rubber to adjust its hardness and strength. Plant oils such as fatty acids, fatty oils and pine oil, mineral oils such as process oils and extenders, and polybutenes. And synthetic compounds such as dibutyl terephthalate and dioctyl phthalate.
[0008]
Acceptance / rejection of the material of the ballpoint pen tip sealing member of the present invention is determined by the following method. Basically, the ballpoint tip nib sealing member itself after molding can be handled as a sample, but in order to suppress errors due to shape factors as much as possible, cut into a specific shape such as a cube. It can also be used as a sample. If the material does not change before and after molding, the raw material itself can be used as a sample, and the shape can be easily measured at that time. First, a sample weighed accurately (assumed to be Ag) is immersed in 10 times the amount (10 Ag) of absolute ethanol and sealed in a stainless steel or glass container with a lid that can be sealed. At this time, the shape of the container is selected so that the sample is completely immersed in ethanol. In addition, when the sample floats, the pressure is reduced to remove bubbles on the sample surface and allow the sample to sink. Next, the container containing the sample and ethanol is allowed to stand in a thermostatic chamber at 50 ° C., and after 1 week, the sample is taken out from a stainless steel wire mesh and left in the thermostatic chamber at 50 ° C. for 24 hours to 48 hours to adhere to the ethanol. Remove. Then, it is allowed to cool at room temperature, and when the sample cools, the weight of the sample (referred to as Bg) is measured. Then, the weight reduction rate (%) of the sample is calculated by the following formula.
[0009]
[Formula 1]
Weight reduction rate (%) = {(A−B) / A} × 100
[0010]
A ballpoint tip nib sealing member having a weight reduction rate calculated from Equation 1 of 10% or less is used.
On the other hand, when a ballpoint pen tip sealing member having a weight reduction rate exceeding 10% is used, it can be said that the phenomenon that the ink discharge amount is reduced or the handwriting is faint is likely to occur. In a severe case, there will be a problem that no ink is produced.
[0011]
[Action]
The plasticizer in the ballpoint pen tip pen sealing member that dissolves in the organic solvent of the ink, the remaining vulcanizing agent, and the substances newly generated by the reaction during vulcanization are present uniformly in the pen tip sealing member. It seems that there is. Therefore, the amount of these penetrating into the ballpoint pen tip in contact with the ballpoint pen tip is the amount of the plasticizer in the penpoint sealing member, the remaining vulcanizing agent, and the substance newly generated by the reaction during vulcanization. It is considered that the amount is almost proportional, and the larger the amount is, the more the amount of leaching into the ink increases. Therefore, in the pen point sealing member whose weight reduction rate by the calculation method using the above-mentioned formula 1 is 10% or less, the plasticizer, the vulcanizing agent, and the reaction that dissolves in the organic solvent of the ink and enters the ink. Even if the newly generated substance is in the ink flow path of the ball-point pen tip nib, it is not enough to greatly reduce the ink discharge amount. .
[0012]
【Example】
Examples and comparative examples are shown below.
Ballpoint pen tip pen sealing members (sealing members 1 to 5) made of five types of nitrile rubbers having different compounding compositions, which were formed into a cylindrical shape having a diameter of 6 mm and a thickness of 2 mm, were prepared. Each of these sealing members 1 to 5 is accurately weighed at room temperature, placed in a screw vial S-30 manufactured by Nidec Rika Glass Co., Ltd., and absolute ethanol manufactured by Kanto Chemical Co., Ltd., which is 10 times the weight of each. In addition, each sealing member was immersed. After sealing with the lid attached to the screw vial S-30, the plate was allowed to stand in a thermostatic chamber at 50 ° C. for 1 week, and then the removed sealing members were placed on a 2 mm stainless steel wire net so as not to overlap each other. After leaving it to stand in a thermostatic chamber for 24 hours, it was taken out, allowed to stand at room temperature, and accurately weighed.
[0013]
Writing instruments 1 to 10 in which the sealing members 1 to 5 were installed in a cap were prepared. The writing tools 1 to 5 are filled with the following ink 1 into K105 manufactured by Pentel Co., Ltd., a ballpoint pen using a white ballpoint pen tip nib (using a 0.5 mm diameter super steel ball). A ballpoint pen using a stainless steel ballpoint pen tip (using a 0.7 mm diameter super steel ball), BK-100 manufactured by Pentel Co., Ltd. is filled with the following ink 2, and each of the sealing members 1 to 3 in the order of the writing instrument number. Corresponding cap with 5 installed.
[0014]
Ink 1
Ethylene glycol (organic solvent) 8.0% by weight
Glycerin (organic solvent) 5.0% by weight
Propylene glycol (organic solvent) 5.0% by weight
Carbon black (black pigment) 4.5% by weight
Styrene-acrylic acid copolymer (polymer surfactant) 3.0% by weight
Water 72.1% by weight
Carboxyvinyl polymer (thickening polymer compound) 0.4% by weight
Triethanolamine (basic pH adjuster) 2.0% by weight
[0015]
Ink 2
Ethylene glycol monophenyl ether (organic solvent) 42.5% by weight
Benzyl alcohol (organic solvent) 14.0% by weight
Dioxyethylene lauryl ether (surfactant) 1.5% by weight
High rack 110H (viscosity adjusting resin) 11.5% by weight
Bali First Violet 1701 (purple dye) 25.0% by weight
Bali First Black 1807 (black dye) 5.0% by weight
Polyvinylpyrrolidone K-90 (viscosity modifier) 0.5% by weight
[0016]
【The invention's effect】
Each writing instrument after filling in the writing test ink is in a state where the cap is never mounted (the ballpoint tip nib is never in contact with the sealing member), and a writing angle of 70 ° with a writing tester manufactured by Seiki Kogyo Co., Ltd. The writing weight was 100 g, the writing speed was 7 cm / sec, 0.1 m per cycle was written in a spiral for 20 m, and the ink discharge amount (C) at that time was measured.
Next, a cap is attached to each writing instrument (at this time, each ball-point pen tip nib is in a state of being inserted into each sealing member sample by 1.2 mm), and the writing instrument is in a horizontal state (a state in which it is laid down) It left still in a 25 degreeC thermostat. After 6 months, it was taken out and written again under the same conditions as before mounting the cap, and the ink discharge amount (D) was measured. In addition, the judgment of the state of writing is performed by determining the writing line skip when there is a break in the handwriting of 0.1 to 1.0 mm, and writing spiral when there is a break longer than 1.0 mm. I counted the number.
The results are shown in Table 1.
[0017]
[Table 1]

[0018]
As described above in detail, when the weight reduction rate is 10% or less, the pen point sealing member for the ballpoint pen of the present invention does not decrease the ink discharge amount even after a long period of time. Keeps the handwriting suppressed as much as possible.

Claims (1)

At least an ink containing an organic solvent is in contact with the ballpoint pen tip pen which is disposed at the distal end of the writing instrument body housing, in the ballpoint pen tip pen ink hole capable occlusion ballpoint pen tip nib sealing member, wherein The material of the ballpoint pen tip pen sealing member is a nitrile rubber compounding composition, and a sample of this nitrile rubber compounding composition is weighed at room temperature and placed in ethanol that is 10 times the weight of the sample in a sealable container. Sealed in an immersed state and allowed to stand at 50 ° C. for 1 week, taken out from the immersion, left at 50 ° C. for 24 hours to remove ethanol, left to reach room temperature, and weighed again before and after A ballpoint pen tip sealing member in which the weight reduction rate of the sample in the weighing is 10% or less .