JP2002067569A - Writing instrument ink tank - Google Patents

Abstract

(57) [Problem] To provide an ink tank in which the remaining ink amount can be visually recognized well. SOLUTION: Block-like polypropylene resin is made of 23
After heating to 0 ° C, melt index 1, water cooling temperature 2
Extrusion molding at 5 ° C. yields an inner wall surface roughness Ra = 5
A transparent ink tank having a height of 20 nm and a maximum height difference PV of 5050 nm is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic resin ink tank for storing writing instrument ink, and more particularly, to a synthetic resin extruded pipe having a ballpoint pen tip as a pen tip connected to the tip. The present invention relates to an ink tank used for a ball-point pen-type writing instrument in which ink is directly filled in the inside.

[0002]

2. Description of the Related Art Conventionally, a writing instrument for directly storing ink in an ink tank is called a "raw ink type writing instrument" or the like.
It can hold a relatively large volume of ink, so that fresh handwriting can be maintained for a long time, and with ink tanks made of transparent wall members, it can be used to check the remaining amount of ink and ink color at a glance. I have. Above all, clarifying the remaining amount of ink that can be used may play a part of the design appearance element of the writing instrument,
Particular emphasis has been placed on them. However, if the ink stored during use adheres to the inner wall surface of the ink tank and remains, the remaining ink adheres to the ink tank, and the remaining ink amount cannot be known. Therefore, a method of improving the ink storage tube has been proposed. For example, Tokuhei 38
In No.-2913, an ink repellent treatment liquid such as silicone varnish is applied to the inner wall surface of the ink storage tube and dried. Further, as described in JP-A-5-270193, there is one in which a high-viscosity composition obtained by gelling polybutene with fine-particle silica is disposed in contact with the interface of the ink. The high viscosity composition can be expected to follow the movement of the ink interface accompanying the consumption of ink, and the effect of scraping off the ink adhering to the inner wall of the ink storage tube with the ink backflow preventer can be expected.

[0003]

In the case where the inner wall surface of an ink tank is subjected to an inner surface coating treatment such as applying an ink repellent treatment liquid such as silicone varnish to the inner wall surface, the treated film may be dyed depending on the type of ink. In some cases, an excessive coating liquid has an adverse effect such as agglomeration of ink. In addition, when the high-viscosity composition is placed in contact with the interface of the ink, various physical properties such as adjusting the viscosity of the high-viscosity fluid, adjusting the vapor pressure to prevent the ink from escaping, and having low compatibility with the ink, etc. The value must be taken into account, and it is difficult to cope with various kinds of inks which are also required to be multicolored, and the production becomes complicated.

[0004]

That is, the present invention relates to a synthetic resin ink tank containing ink for a writing instrument, wherein an inner wall surface of the ink tank has an arithmetic average roughness (R).
a) is 500 nm or less, and the maximum height difference (P−
V) is 5000 nm or less.

The shape of the ink tank can be used without limitation as long as it can be obtained by molding a synthetic resin, such as extrusion molding, injection molding, etc., in addition to cylindrical (pipe) having a circular cross section. However, when it is desired to obtain the surface roughness of the inner wall surface of the molded product depending on the surface condition of the core pin of the mold, it can be said that injection molding using the cavity as a split mold is preferable.

The synthetic resin material constituting the ink tank includes polypropylene resin, polyethylene resin,
Polyvinyl chloride resin, methacrylic resin, polyamide resin, polycarbonate resin, polystyrene resin, acrylonitrile butadiene styrene resin and the like can be used, among which, from the viewpoint of the permeability of the ink solvent and the transparency for visual recognition of the inner surface, polypropylene Resins, polyamide resins, polyvinyl chloride resins, and polyethylene resins are preferred. Further, in order to realize the surface roughness of the inner wall surface described above, a polypropylene resin or a polyamide resin is preferable.

The arithmetic average roughness (Ra) is JIS B060
The center line average roughness defined in 1 was measured on the measurement surface (6400
(μm ² , square of 80 μm on ^each side), three-dimensionally extended, and a value obtained by averaging the absolute values of deviations from the reference plane to the designated plane was used. The surface roughness was measured using a model name (SPI3800N, manufactured by Seiko Epson Corporation).

The maximum height difference (PV) is the difference between the maximum height (Zmax) and the minimum height (Zmin) on the measurement surface.

[0009]

The arithmetic mean roughness (Ra) and the maximum height difference (P-
V) is considered to be a factor affecting flow resistance when the contacting ink moves. That is, when Ra is a small value, it indicates that the concaves and convexes formed thereon are gentle, and it is considered that the ink does not easily diffuse along the concaves (grooves). In addition, the fact that PV is small means that the height of the projections of the unevenness is low, and it is considered that this is unlikely to hinder the movement of the ink. In any case, it is unlikely that the value will become zero as a practical problem, so it is considered preferable to reduce the value by devising the molding conditions and the inner surface treatment of the mold.

[0010]

EXAMPLES Examples and comparative examples are shown below. Using a polypropylene resin or a nylon resin, ink tanks for writing instruments shown below were prepared. Each of the ink tanks was formed into a pipe having a circular cross section with an outer diameter of 6.2 mm and an inner diameter of 4.7 mm, and had various inner surface roughnesses.

Example 1 After heating a block-shaped polypropylene resin to 230 ° C., a melt index 1 (a value indicating fluidity when extruding a melted resin raw material, and the value is JIS)
K, measured by the method described in K691-2-2), a pipe having an inner wall surface roughness of Ra = 480 nm and a maximum height difference of PV = 4780 nm is produced by extrusion molding under a condition of a water cooling temperature of 25 ° C., and a transparent writing instrument. Was obtained.

Example 2 A block-shaped polypropylene resin was heated to 230 ° C., then melt-indexed 2 (adjustment of the melt-index was performed by mixing a release material containing calcium carbonate as a main component in a molten resin) and water cooling. Extrusion molding at a temperature of 25 ° C. gave an inner wall surface roughness Ra = 220 nm and PV =
A 3020 nm pipe was produced to obtain an ink tank for a transparent writing instrument.

Example 3 A block-shaped polypropylene resin was heated to 230 ° C., and then extruded under conditions of a melt index of 2.5 and a water-cooling temperature of 25 ° C. to obtain an inner wall surface roughness Ra = 195 nm, P
A pipe of −V = 2170 nm was produced to obtain an ink tank for a transparent writing instrument.

Example 4 A block-shaped 12 nylon resin was heated to 250 ° C., and then extruded under the conditions of a melt index of 1 and a water cooling temperature of 25 ° C. to obtain an inner wall surface roughness Ra = 73 nm and PV = PV.
A 520 nm pipe was prepared to obtain an ink tank for a transparent writing instrument.

Example 5 A block-shaped 12 nylon resin was heated and melted at 250 ° C., and then extruded under conditions of a melt index of 2.2 and a water cooling temperature of 25 ° C. to obtain an inner wall surface roughness Ra = 54 nm, P
A pipe of −V = 310 nm was produced to obtain an ink tank for a transparent writing instrument.

COMPARATIVE EXAMPLE 1 A block-like polypropylene resin was heated to 230 ° C., and then extruded under a cooling condition of a melt index of 1 and a water temperature of 50 ° C. to obtain an inner wall surface roughness Ra = 350 nm, PV
= 7548 nm pipe was produced to obtain an ink tank for a transparent writing instrument.

COMPARATIVE EXAMPLE 2 After heating a block-like polypropylene resin to 240 ° C., the inner wall surface roughness was Ra = 734 nm by extrusion molding under a cooling condition of a melt index of 3 and a water temperature of 50 ° C., PV
= 10210 nm was produced to obtain a transparent writing instrument ink tank.

Comparative Example 3 A block-shaped polypropylene resin was heated to 240 ° C., and then extruded under a cooling condition of a melt index of 1 and a water temperature of 50 ° C. to form an inner wall surface having a roughness of Ra = 620 nm and PV.
= 4530 nm pipe was obtained to obtain an ink tank for a transparent writing instrument.

[0019]

With respect to each of the ink tanks shown in the above Examples and Comparative Examples, it was confirmed whether or not ink adhered to the inner wall surface of the pipe.

Ink Adhesion Confirmation Test Each of the ink tanks of the examples and comparative examples was connected with the following nibs for the corresponding inks, and filled with the inks shown below to prepare the structure of the writing implement.
After standing for 10 days in an environment of 60 ° C. and 60% humidity, a writing speed of 10 cm / second, a writing load of 100 g, and a writing angle of 70 ° were applied to NS- <55> Kaete paper manufactured by Intec Co., Ltd. Spiral writing was performed using a TS-4C-10 model. The adhesion of the ink to each ink tank after writing 700 m was visually checked. Table 1 shows the results.

Ink 1 (water-based gel ink) MA100 (carbon black, manufactured by Mitsubishi Kasei Kogyo Co., Ltd.) 8.0% by weight Carboxymethylhydroxypropylated gar gum (water-soluble thickening polysaccharide) 1.5% by weight Carrageenan (water-soluble) Thickening polysaccharide) 0.2% by weight NP-20 (polyoxyethylene nonylphenyl ether, manufactured by Nikko Chemicals Co., Ltd.) 2.0% by weight Benzoic acid (rust inhibitor) 0.4% by weight propylene glycol 9.0 80.9% by weight of water 80.9% by weight In the above components, components other than carboxymethylhydroxypropylated guar gum and carrageenan were mixed and stirred by a ball mill for 3 hours, and then carboxymethylhydroxypropylated gargam and carrageenan were added and dispersed again for 2 hours. Was carried out to obtain a black aqueous ink composition having a viscosity of 2018 cp.
The viscosity was measured with a Tokimec ELD viscometer ST rotor 2.5 rpm.

Ink 2 (oil-based ink) Ethylene glycol monophenyl ether 44.0% by weight Benzyl alcohol 15.0% by weight Dioxyethylene lauryl ether 1.5% by weight Dodecylethanolamine 0.5% by weight Hilac 110H (ketone resin) 8.0% by weight Varifast Violet # 1701 (Dye, manufactured by Orient Chemical Industry Co., Ltd.) 25.0% by weight Varifast Black # 1807 (Dye, manufactured by Orient Chemical Industry Co., Ltd.) 5.0% by weight Polyvinylpyrrolidone K-90 (manufactured by BASF) 1.0% by weight The above mixture was stirred at 80 ° C. for 6 hours to have a viscosity of 6,870 cp.
(25 ° C.) black ink was obtained. The viscosity was measured with an ELD viscometer ST rotor 10 rpm manufactured by Tokimec.

Pen tip 1 (ball-point pen tip for water-based gel ink) A ball-point pen in which a stainless steel ball holder connected to the tip of a refill KF5 of a water-based gel ink ballpoint pen hybrid (K105) manufactured by Pentel Co., Ltd. holds a carbide ball. Chips.

Pen tip 2 (ballpoint pen tip for oil-based ink) Refill B of oil-based ballpoint pen BK70 manufactured by Pentel Co., Ltd.
A ballpoint pen tip in which a stainless steel ball holder connected to KL7 holds a carbide ball.

[0025]

[Table 1]

As described above, it has been found that the ink tank of the writing instrument of the present invention can prevent the adhesion of the ink to the inner wall surface of the pipe. This fact makes it possible to provide a writing instrument with a clear ink remaining amount.

Claims (1)

[Claims] 1. An ink tank made of a synthetic resin which contains ink for a writing instrument, wherein an inner wall surface of the ink tank has an arithmetic average roughness (Ra) of 500 nm or less and a maximum height difference (PV). Is 5000 nm or less.