JPH03246099A - Pen point of liquid writing utensil - Google Patents

Abstract

PURPOSE:To enhance writing life and to improve a writing feeling by externally heating a molded body composed of a crystalline polymer having gaps for the outflow of ink to specific temp. to stretch the same in its axial direction. CONSTITUTION:As a crystalline polymer, a polyacetal resin or a polyamide or polyester resin having a polar group in its molecule is used. For example, the polyacetal resin is melted under heating and subjected to extrusion molding by an extrusion molding machine whose leading end is equipped with a die having a large number of small holes arranged thereto so as to obtain a state having gaps of a profile cross-section after extrusion molding. This molded body is externally heated to 150 deg.C or lower by a heater to be stretched and the stretched one is further shortly cut to obtain a pen point having gaps of a profile cross-section. For example, a pipe 3 is mounted on the outer peripheral part of the pen point 2 wherein the gaps 1 are radially opened to the outer surface thereof in the radius direction if necessary before use.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pen nib for a liquid writing instrument having a gap for ink outflow, and more specifically, to a nib of a liquid writing instrument that significantly increases the writing life by improving wear resistance. Moreover, the present invention relates to a pen nib of a liquid writing instrument that has a much better writing taste.

[Conventional technology]

Conventionally, most pen nibs of this type have been obtained by extrusion processing thermoplastic resins, and the resins used include single substances such as polyamide, polyurethane, and polyacetal, or composites of these resins mixed with fillers. materials were commonly used.

Although the liquid such as ink acts as a lubricant when pen nibs made of the above-mentioned materials cause sliding friction during writing, they have the disadvantage of relatively high wear, especially for people who write with high pressure. This tendency was noticeable when using paper with high surface roughness. In other words, all of the resins mentioned above have problems with respect to abrasion resistance, which affects the writing life of the pen tip. Therefore, this low abrasion resistance is a major obstacle in the design of liquid writing instruments.
In particular, the following two points can be mentioned.

The point is that there needs to be a balance between the amount of ink stored in the ink absorber and the amount of wear on the pen tip, but since conventional pen tips have a large amount of wear, there is enough ink remaining. Despite this, the lifespan of liquid writing instruments is limited by nib wear.

Another point is that by making the ink absorbing body into a cartridge, the writing life can be greatly extended, but with the conventional pen nib that has a gap for ink flow with an irregular cross section, the wear resistance is low, and the liquid It is hardly useful to have a writing instrument with a replaceable ink cartridge.

[Problem to be solved by the invention]

By the way, the present inventor has been researching pen nibs with various gaps for ink to flow out, and has found materials with high wear resistance,
Although abrasion can be solved by using glass, ceramics, various metals, etc., compared to pen nibs made of plastic materials, these materials reduce the writing quality, which is another important characteristic of a writing instrument nib. It has the disadvantage of being extremely poor, and in particular, the thinner the line width is, the worse the writing quality tends to be, and the paper fibers etc. get stuck in the gaps for ink to flow out, causing eye irritation. This had problems such as clogging and disturbing the drawn lines.

Therefore, the present invention has been made in consideration of the above circumstances.
Its purpose has traditionally been j! To provide a pen nib of a liquid writing instrument whose writing life is greatly improved by improving abrasion resistance and which has a much better writing taste, manufactured at a low cost using an industrially simple method. It is in.

[Means to solve the problem]

As a result of intensive research to achieve the above object, the present inventor has
The molded product obtained by molding a crystalline polymer is used as a heat source when stretching the molded product in the axial direction at a high magnification, and the molded product obtained by external heating improves the writing properties, especially the abrasion resistance and writing feel. The present invention was completed with the idea of creating an excellent nib for liquid writing instruments.

That is, a molded product of an unstretched crystalline polymer usually has a mixture of crystalline parts in which the molecular chains are properly arranged and amorphous parts in which the molecular chains are disordered. This amorphous portion causes a decrease in mechanical strength such as elastic modulus.

Therefore, in order to improve mechanical strength, the molecular arrangement of this amorphous part is adjusted and crystallized, and the crystalline part becomes a lamellar crystal with folded molecular chains. It is necessary to unravel the molecular chains and orient them in one direction.

The crystalline polymer used in the present invention is a known one, and as long as it has a polar group in the molecule, commercially available polyacetal resins, polyamide resins, polyester resins, etc. can be used, but in particular polyacetal resins can be used. is a material in which rearrangement of molecular chains can easily occur due to its simple molecular structure and weak dipole interaction, and is preferable for reasons such as formability as a pen tip, abrasion resistance, and ink wettability.

In order to obtain the desired pen nib of the present invention, it is preferable to use a known extrusion molding machine or injection molding machine that is used for molding ordinary thermoplastic resins. It is preferable to use an extrusion molding machine from the viewpoint of manufacturing cost. In any method, it is desirable that the speed of the melt flow and the melt temperature can be sufficiently controlled.

Next, the hollow continuous body obtained by extrusion molding and having gaps for ink flow is stretched. The temperature of the molded product during stretching must be 150°C or lower. This is because the melting point of polyacetal resin is close to that of polyacetal resin, and even if the resin is stretched in a molten state, the same strength will not be improved. In other words, the temperature at which stretching is performed to obtain a high modulus of elasticity is related to the crystal relaxation temperature, which is the temperature at which segments begin to move within the crystal. Doesn't improve. At this time, liquid flow is occurring, and internal stress does not work sufficiently, so even though the apparent shape changes, the physical properties of the sample do not change. Therefore, the temperature of the molded product during stretching is 130 to 150°C, and in the case of polyacetal resin, the optimum temperature is around 140°C.

Then, the obtained stretched product is cut into short lengths and the tip is polished into a pen point shape, thereby making it possible to create a highly stretched pen point.

[For production]

The highly stretched pen nib obtained by the present invention has the following excellent advantages.

(1) Because it has a unidirectionally oriented and dense crystal structure,
Excellent abrasion resistance when writing.

(2) The strength of the pen core itself is increased, so even people who use high writing pressure will not damage the pen tip.

(3) Since the structural member of the pen tip is made of plastic, it has excellent writing quality, unlike pen nibs made of glass, ceramics, various metals, etc.

(4) Since the molding equipment can be used as is, a normal thermoplastic resin equipment, mass production is possible and the unit price per piece is low.

〔Example〕

Next, the present invention will be explained in more detail based on examples.

In this example, polyacetal resin is used as the crystalline polymer, but other than this, polyamide resin, polyester resin, etc. can be used as long as it has a polar group in the molecule.

In this example, polyacetal resin is heated and melted, and after extrusion molding, a die with a large number of small holes is attached to the tip so as to have gaps in the irregular cross section, and extrusion molding is carried out. The stretching ratio of this molded product was set to 12 times, and the temperature was set to 150.
It was stretched by external heating using a heater or the like so that the temperature was below 0.degree. C., and then cut into short lengths to obtain a pen nib having a gap with an irregular cross section.

This pen nib was assembled into a writing instrument, and the wear amount of the nib was measured when writing was performed using a mechanical writing tester, and a sensory test was conducted by an experienced evaluator to determine the writing feel. Moreover, the bending elastic modulus was measured using the pen tip as it was. The results are shown in Table 1.

Next, an embodiment of a gap of irregular cross section for ink to flow out at the pen tip will be described with reference to FIGS. 1 to 7. The first embodiment shown in Fig. 1 is a pen nib 2 in which a radial gap 1 is opened radially on the outer surface, and if necessary, a vibrator 3 is attached to the outer periphery as shown in Fig. 2 for use. . In addition, in the second embodiment shown in FIG. 3, a branch-like gap 1 in the circumferential direction is connected to a pen nib 2 in the middle of a radial gap 1 opened on the outer surface in the radial direction.
It is.

Furthermore, the third embodiment shown in FIG. 4 is a semicircular pen nib 2 with several parallel gaps 1 opened on the flat surface, and as shown in FIG. They are combined and a vibrator 3 is attached to the outer periphery and fixed.

The fourth embodiment shown in FIG. 6 has a fan-shaped gap 1 with a complicated shape that opens toward the center, and as shown in FIG. and fix it.

[Comparative example]

Polyacetal resin is heated and melted, and after extrusion molding, it is molded using an extrusion molding machine equipped with a die equipped with a large number of small holes at the tip so that there are gaps in the irregular cross section, and then cut into short lengths to create gaps in the irregular cross section. A pen nib having the following characteristics was obtained.

Measurement of the bending elastic modulus of the pen tip obtained by the above operation,
After assembling it into a writing instrument, the amount of wear was measured using a military writing tester, and the writing quality was tested using a sensory test by an expert. The results are also shown in Table 1.

〔Test results〕

Table 1 However, in the abrasion loss test, the conditions for the writing test using a mechanical writing tester were that only the writing load was 100 gf, but the other conditions were in accordance with JIS-3-6037-1986 Marking Ben.

〔Effect of the invention〕

As explained above, the pen tip according to the present invention has writing characteristics,
In particular, it has excellent abrasion resistance and writing quality, and as is clear from the test results above, with conventional pen nibs, even though there is still sufficient ink remaining, it becomes impossible to write after a short writing distance. However, it has become possible to write over much longer distances.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of the present invention, FIG. 2 is a cross-sectional view showing another usage form of the first embodiment, and FIG. 3 is a cross-sectional view showing a second embodiment of the present invention. FIG. 4 is a cross-sectional view showing a third embodiment of the present invention, FIG. 5 is a cross-sectional view showing another usage form of the third embodiment, and FIG. 6 is a fourth embodiment of the present invention. FIG. 7 is a cross-sectional view showing another mode of use of the fourth embodiment. 1... Gap, 2... Pen tip, 3... Pipe.

Claims (1)

[Claims] A pen nib for a liquid writing instrument, characterized in that it is made by stretching a crystalline polymer molded product in the axial direction while externally heating it to a temperature of 150° C. or lower, which has a gap for ink to flow out.