JPH03237000A - Pen point of liquid writing utensil - Google Patents

Abstract

PURPOSE:To enhance writing life to a large extent by improving abrasion resistance and to inexpensively prepare pen point markedly improved in its writing feeling by stretching a non-stretched molded body of a crystalline polymer having ink outflow gaps while applying dielectric heating due to a microwave and external heating thereto in combination. CONSTITUTION:As a heating source, dielectric heating due to a microwave and external heating having a temp. gradient in an axial direction are together used and a molded body having ink outflow gaps obtained by molding a crystalline polymer is stretched in its axial direction under heating to obtain a highly stretched molded body. This molded body becomes the pen point of a liquid writing utensil excellent in writing characteristics, especially, in abrasion resistance and a writing feeling. The molded body is effectively heated by especially heating the non-crystalline part thereof from inside using a microwave and the crystalline part thereof is especially heated from the outside by together using external heating. Further, a temp. gradient is provided to the external heating to relax the heat reckless phenomena apt to be generated in microwave heating.

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 molding and pressurizing thermoplastic resins, and the resins used include single substances such as polyamide, polyurethane, and polyacetal, or composites of these resins mixed with fillers. materials commonly used together.

Although the liquid such as ink acts as a lubricant when pen nibs made of the above-mentioned materials undergo 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 used together or when used together with paper with a large 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 storage body into a cartridge, the writing life can be greatly extended, but the conventional pen nib with an irregular cross section and a gap for ink outflow has low abrasion resistance, which prevents liquid from flowing. Writing instruments that use an ink cartridge replacement system are rarely used for A.

[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. 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, making it difficult to draw. This had problems such as clogging and disturbing the drawn lines.

Therefore, the present invention has been made in consideration of the above circumstances.
The aim is to significantly improve writing life and abrasion resistance, which could not be achieved with conventional methods.
Moreover, it is an object of the present invention to provide a pen nib of a liquid writing instrument which has a much better writing taste and is manufactured at a low cost using an industrially simple method.

[Means to solve the problem]

As a result of intensive research to achieve the above object, the present inventor has
Dielectric heating using microwaves and a temperature gradient in the axial direction are used as heating sources when stretching a molded product obtained by molding a crystalline polymer, which has gaps for ink to flow out, at a high magnification in the axial direction. A molded article with a high draw ratio obtained by external heating has excellent writing properties, especially abrasion resistance and writing feel7.
The present invention was completed with the idea that it could be used as a pen nib for night-time 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 force causes a decrease in mechanical strength such as y < li properties.

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

Conventionally, the technique used to increase the elastic modulus of plastics was to heat the plastics externally using hot air, etc. to make them easier to move, stretch them, arrange the molecular chains, and crystallize them. Since the method involves heating from the outside, it is difficult to heat the inside sufficiently for large-diameter molded products in a short period of time, so if stretched at a high magnification, the material will break during stretching, and the stretching magnification is also limited to low magnifications. was.

In the present invention, microwaves are used in combination to heat the amorphous portion from the inside, thereby effectively heating the material, and external heating is used in combination to heat the crystalline portion from the outside. Additionally, a temperature gradient is added to the external heating to alleviate the thermal violence phenomenon (a phenomenon in which the sample temperature rises rapidly) that is common with microwave heating. By performing these methods simultaneously, continuous and effective stretching became possible.

The crystalline polymer used in the present invention is a known one, and commercially available polyacetal resins, polyamide resins, polyester resins, etc. can be used as long as they have polarity in the molecule. 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. From the viewpoint of production cost, it is preferable to use an extrusion molding machine. In any method, it is desirable that the speed of the melt flow and the melt temperature be sufficiently controlled.

Next, the hollow continuous body obtained by stretch molding and having gaps for ink outflow is stretched. The stretching device used here is composed of a microwave heating device for heating the molded product, a feeding machine that works to stretch the heated material, and a take-off machine. Microwave heating equipment uses an oscillator,
There is a cylindrical waveguide for heating, a rectangular waveguide to connect them, and a dummy to absorb excess microwaves.

Note that the oscillation frequency of the oscillator is 2450 MHz.

In addition, a heater for external heating was installed on the outer peripheral surface of the cylindrical waveguide for heating, so that the atmospheric temperature inside the cylindrical waveguide could be arbitrarily controlled. When stretching the molded product using this apparatus, any desired stretching ratio can be obtained by changing the speeds of the feeder and take-up machine. The obtained stretched product is cut into short lengths and the tip is polished into a pen point shape to create a highly stretched pen nib.

[For production]

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

(1) Both the amorphous portion and the crystalline portion are effectively heated, and stretching stress can be applied effectively. Furthermore, since it is oriented in one direction and has a dense crystal structure, it has excellent abrasion resistance during writing.

(2) Since it is possible to stretch to a high magnification, the strength of the pen core itself is increased, and even people who use high writing pressure will not damage the pen tip.

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

(4) Since ordinary thermoplastic resin molding equipment can be used as is, 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 in combination as the crystalline polymer, and in addition to this, polyamide resin, polyester resin, etc. can be used as long as they have 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. This molded product was stretched using a microwave heating stretching device at a stretching ratio of 12 times, and cut into short lengths to obtain a pen tip having a gap in 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.

Furthermore, the bending elastic modulus was measured using the pen tip as it was.

The results are shown in Table 1.

Next, the microwave heating stretching apparatus will be explained based on FIG. 1.

In the figure, extrusion molding is performed using an extrusion molding machine 10, and cooling tank 1
- The stretching device for stretching the hollow continuous body having an ink flow gap obtained through step 1 includes a microwave heating device 2o for heating this molded body, and a feeding machine that works to stretch the heated body. 12, and a collection machine 13. The microwave heating device 20 includes an oscillator 21, a cylindrical waveguide 22 for heating, a rectangular waveguide 23 connecting these,
It is more powerful than Dummy 24, which absorbs excess microwaves. Note that the oscillation frequency of the oscillator 21 is 2450MHz
It is.

Further, a heater for external heating was installed on the outer peripheral surface of the cylindrical waveguide 22 for heating, so that the atmospheric temperature inside the cylindrical waveguide 22 could be arbitrarily controlled.

Here, a temperature gradient is applied to the external heating from a low temperature to a high temperature along the stretching direction to alleviate the thermal runaway phenomenon that tends to occur in microwave heating. When stretching the molded product using this apparatus, by changing the speeds of the feeder 12 and take-off machine 13, any stretching ratio can be obtained. The obtained stretched product is cut into short lengths and the tip is polished into a pen point shape to create a highly stretched pen nib.

By the way, an embodiment of a gap having an irregular cross section for ink to flow out in the pen tip will be described with reference to FIGS. 2 to 8. The eleventh embodiment shown in Fig. 2 has a pen nib 2 with a radial gap 1 opened radially to the outer surface, and if necessary, a vibrator 3 can be attached to the outer periphery as shown in Fig. 3 for use. do. Also,
The second embodiment shown in FIG. 4 is a pen nib] 0 2 in which branch-shaped gaps 1 in the circumferential direction are communicated in the middle of a radial gap 1 opened on the outer surface in the radial direction.

Furthermore, the third embodiment shown in FIG. 5 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 fixed by attaching a pipe 3 to the outer periphery.

The fourth embodiment shown in FIG. 7 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 at the tip with many small holes arranged 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 properties 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 writing tester, and the writing feel was tested using a sensory test by an expert. The results are also shown in the table below.

〔Test results〕

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 similar to J15-6037-1.986 marking pen.

〔Effect of the invention〕

As explained above, the pen nib according to the present invention has excellent writing characteristics, especially abrasion resistance and writing quality, and as is clear from the above test results, ink still remains sufficiently in the conventional pen nib. Although it used to be impossible to write at short writing distances, it has now become possible to write at significantly longer distances.

1...Gap, 2...Nib, 3...Pipe,]
0...fllllll shape, 20... microwave heating device 21... oscillator, 22... cylindrical waveguide for addition.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a microwave heating stretching apparatus used in carrying out the present invention, FIG. 2 is a cross-sectional view showing an eleventh embodiment of the present invention, and FIG. 3 is a diagram showing other embodiments of the present invention. FIG. 4 is a cross-sectional view showing a second embodiment of the present invention, FIG. 5 is a cross-sectional view showing a third embodiment of the present invention, and FIG. 6 is a cross-sectional view showing a third embodiment of the present invention. FIG. 7 is a cross-sectional view showing a fourth embodiment of the present invention, and FIG. 8 is a cross-sectional view showing another combination of the fourth embodiment.

Claims (1)

[Claims] An unstretched crystalline polymer material with gaps for ink flow is heated using dielectric microwaves and external heating with a temperature gradient from low to high ambient temperature along the stretching direction. A pen nib for a liquid writing instrument that is characterized by being stretched while stretching.