JP2741056B2 - Liquid writing instrument nib - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a nib of a liquid applicator having a gap for ink outflow, particularly obtained by molding a compounded composition containing a thermoplastic liquid crystal polymer.

(Prior art) Conventionally, a nib having an ink outflow gap has been obtained by extruding a thermoplastic resin such as polyamide, polyurethane, or polyacetal. In these nibs, the ink serves as a lubricant. Nevertheless, there is a drawback in that the wear due to rubbing during writing is relatively large, and this lack of wear resistance limits the life of the liquid writing instrument and is a great disadvantage in design. That is, the amount of ink in the ink occluding body must be limited due to the large wear of the pen tip, and it has not been possible to convert the ink occluding body into a cartridge for a replacement system. In addition, since these resin nibs have low flexural modulus and bending strength, they have the disadvantage that the nibs are deformed or loosened during writing, and this also shortens the life of the writing implement. By the way, if it is merely to improve the wear resistance of the pen tip, for example, it may be made of glass, ceramics or various metals, but this kind of pen tip has a drawback that the writing quality is extremely poor, especially the writing line width. There is a tendency that the thinner the image, the worse the writing quality. In addition, this type of pen tip also has drawbacks such as clogging due to paper fibers penetrating into the gap for discharging the ink flow 4 and disturbing drawing lines.

In order to solve the above-mentioned drawbacks of the conventional pen tip, the present applicant has filed a new application (Japanese Patent Application No. 62-324382) by molding a compounded composition containing a thermoplastic liquid crystal polymer. A pen tip for liquid writing implements was proposed.

(Problems to be Solved by the Invention) However, subsequent studies have revealed that a pen tip obtained by molding a compounded composition containing a liquid crystal polymer has the following adverse effects on production. That is, machining such as cutting or polishing is required to complete the pen tip, but due to the large degree of molecular orientation of the liquid crystal polymer, cracks and fluffing are likely to occur during this machining,
Further, since the melt viscosity of the liquid crystal polymer is low and the spinnability is large, the polishing powder is fused to the work in the polishing process and is difficult to be discharged. .

Therefore, the present invention makes use of the advantages of the liquid crystal polymer, has excellent abrasion resistance, has a high elastic modulus and high strength, has excellent writing taste, and has excellent workability without the above-mentioned adverse effects during machining. The purpose is to provide a new liquid writing instrument nib.

(Means for Solving the Problems) In order to achieve the above object, the pen of the liquid writing implement of the present invention has a liquid writing implement having an ink outflow gap obtained by molding a compounded composition containing a thermoplastic liquid crystal polymer. Characterized in that a powder having an average particle size of 20 μm or less and a softening temperature or a decomposition temperature higher than a molding temperature is added to the above-mentioned composition.

Here, the thermoplastic liquid crystal polymer used in the present invention is an aromatic polyester-based resin, generally, para-hydroxybenzoic acid or para-acetoxybenzoic acid, terephthalic acid, 6-hydroxy-2naphthalene carboxylic acid, biphenol, It is obtained by copolymerizing one or more kinds such as polyethylene terephthalate. In the present invention, a known or commercially available thermoplastic liquid crystal polymer can be used. The matrix resin in the compounded composition of the present invention must be entirely the above-mentioned liquid crystal polymer or at least contain the liquid crystal polymer, but in order to effectively exhibit the performance of the liquid crystal polymer, the matrix resin is required. The content of the liquid crystal polymer in the above is preferably 50% by weight or more.
The other components of the matrix resin include a thermoplastic resin capable of polymer blending with a liquid crystal polymer, for example, one or more resins such as polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, polyamide, and polycarbonate. Can be selected as needed.

The powder to be added to the compounded composition in the present invention may be organic or inorganic, but it is necessary that the softening temperature or the decomposition temperature is higher than the molding temperature so that melting and decomposition do not occur during molding, and the average particle size Should be 20 μm or less, and preferably 10 μm or less. The amount of powder to be added depends on the type and mixing ratio of the liquid crystal polymer of the matrix resin, the type and mixing ratio of the resin other than the liquid crystal polymer of the matrix resin,
It varies depending on the particle size of the powder to be added, the aspect ratio, the oil absorption, the properties of the powder itself such as surface functional groups, the stretching ratio at the time of molding, the properties of the intended nib, and the like.
It is good to mix 1 to 50% by weight, preferably 1 to 20% by weight. The surface of the powder may be pretreated by a conventional method using a surfactant or a coupling agent in advance. In addition, since the addition of the powder has an effect that the improvement of the abrasion resistance and the increase of the flexural modulus and the flexural strength of the liquid crystal polymer are slightly hindered, the profile of the powder is minimized in order to minimize this effect. A needle-like or scale-like material with a large aspect ratio is good, and in particular, since the liquid crystal polymer has the property of one-dimensionally aligning, it should be scale-like in consideration of the balance between anisotropy and isotropicity. Is preferred. Also, to improve the moldability by improving the lubricity of the compound composition,
It is preferable to select a powder having a lubricating surface for the purpose of improving the writing taste as a pen tip during writing and minimizing wear of the pen tip. In addition, it is expected that the ink used for the pen tip is inevitably varied, and the color of the pen tip is preferably white or light. Therefore, the color of the powder is also preferably white or light.

In the present invention, additives such as stabilizers and lubricants can be added to the blended composition, if necessary, in addition to the above essential elements.

In order to obtain the pen tip by molding the above composition, first disperse or knead the composition using a commonly used thermoplastic resin disperser or kneader, and granulate as necessary. A molding pellet may be formed by a conventional method using a known molding machine used for molding a normal thermoplastic resin, and then the molding may be performed in a usual manner. From the viewpoint, it is preferable to employ an extrusion molding method, and more preferably a modified extrusion molding method. However, whichever method is employed, it is preferable that the speed of the melt flow of the resin and the melting temperature can be sufficiently controlled. Next, the above-mentioned molded product may be cut into a predetermined size using an ordinary plastic processing machine, and the end may be polished into a predetermined shape.

(Function) The liquid crystal polymer has a property that the whole structure is composed of rigid molecules, and the molecules are orderly largely bent in a molten state. As a result, it is possible to obtain a molded product having a crystal structure in which the degree of orientation is larger as the surface is closer to the surface and the structure is denser. However, this anisotropy is not suitable for cutting or cutting of a molded product, and causes troubles such as cracking and fluffing as described above. Therefore, when a powder having an average particle size of 20 μm or less and a softening temperature or a decomposition temperature higher than a molding temperature is added to the compounded composition as in the present invention, the orientation of the liquid crystal polymer is hindered to the extent that the excellent advantages are not impaired. As a result, it is possible to prevent the molded product from being damaged during machining. In addition, the spinnability of the liquid crystal polymer is suppressed by the addition of the powder, and as a result, the problem that the polishing powder is smoothly discharged during the polishing process and the gap for ink outflow is filled is eliminated. It should be noted that selecting a scale-like powder makes it easier to balance anisotropy and isotropicity, and selecting a powder having lubricity on its surface makes it easier to write as a nib. And the moldability is also improved, and the dimensional accuracy is improved.

(Example) Thermoplastic liquid crystal polymer 80% by weight (Vectra A950 manufactured by Polyplastics) Polyethylene terephthalate 15% by weight (Berbet DGFG-1 manufactured by Kanegafuchi Chemical Industry) Talc powder 5% by weight Biaxially blended composition comprising the above composition The mixture is dispersed and kneaded using a screw-type kneading machine, and the discharged product is hot-cut to obtain a molding pellet. After the hot-melt extrusion molding, the pellet is fused into a state having a gap for ink outflow of an irregular cross section. Using an extruder equipped with a die with a large number of small holes at the tip, a molded product with a diameter of 0.5 mm is obtained.Then, after cooling this molded product, short cuts are made using a shear cutter. Then, one end face was processed into a hemispherical shape using a polishing machine equipped with an 80-mesh whetstone to obtain a nib product.

Check the defect rate during cutting and polishing in the manufacturing process of the pen tip of the above embodiment, and assemble the pen tip into a writing implement,
The coefficient of friction was measured by a friction coefficient tester, the amount of wear on the pen tip was measured by a mechanical writing tester, the sensory test of writing taste by a skilled person, and the three-point bending test of bending elastic modulus and bending strength were performed. . In addition, a pen tip of a comparative example was obtained by using the same processing machine as the example with the compounding composition obtained by removing the talc powder from the compounding composition of the above example, and the same measurement and test as the pen tip of the above example were performed. Was done. The results are shown in the table below. In addition, in the wear amount measurement, the condition of the writing test by the mechanical writing test machine was 100 gf only for the writing load,
Others conformed to [JIS-S-6037-1986 marqueg pen].

(Effects of the Invention) The present invention is as described above, and as is apparent from the above test results, does not significantly impair the advantages of the liquid crystal polymer, that is, has excellent flexural modulus and flexural strength with excellent wear resistance. In addition, while maintaining good writing quality, there is an effect that the machinability is extremely improved to prevent cracking and fluffing of the pen tip and also to prevent clogging of the ink outflow gap due to abrasive powder.

Claims (4)

(57) [Claims] In a pen tip of a liquid writing instrument having an ink outflow gap obtained by molding a composition containing a thermoplastic liquid crystal polymer, the composition has an average particle size of 20 μm.
A nib of a liquid writing instrument, wherein a powder having a softening temperature or a decomposition temperature higher than a molding temperature at a temperature of m or less is added. 2. The nib of a liquid writing instrument according to claim 1, wherein the powder has a scaly shape. 3. The nib of a liquid writing instrument according to claim 1, wherein the powder has lubricity on its surface. 4. The nib of a liquid writing instrument according to claim 1, wherein the color of the powder is white or light.