JPH0117877B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to an easy-to-cut plastic pen body. In particular, the present invention relates to an easy-to-cut plastic pen body formed from a homogeneous compatible material obtained by melting and homogeneously blending two or more thermoplastic resins having different chemical structures. More specifically, in cases where the initial point shape of a pen body that can be easily cut with various types of cutting tools has become deformed due to wear during writing, making it impossible to write in fine print, The aim is to provide a plastic pen body that can be recycled to maintain fine writing and that can be easily cut into a tip shape suitable for the purpose. Conventional technology Pen bodies of the type molded by melt extrusion molding of thermoplastic resin and having ink passages running through the inside of the molded body in the axial direction have been used as pen bodies of marking pens, but A pen body made of a homogeneously compatible material, which is a melt-molded product made of one resin and a homogeneous melt blend of two or more types of thermoplastic resins with different chemical structures, has not been put to practical use, and no proposals related to this have been disclosed. . Problems to be Solved by the Invention The present inventors investigated the machinability of thermoplastic resins using knives and other cutting tools, and found that
It was discovered that a material made by homogeneously melt-blending different types of thermoplastic resins can be cut more easily than a single resin system, and the easy-cutting plastic pen body of the present invention was completed. Means for Solving the Problems The present invention is a plastic pen body (illustrated in FIGS. 1 and 2) that is molded by extrusion molding of a thermoplastic resin and has an ink passage extending through the molded body in the internal axial direction. is molded from a homogeneous compatible material with a flexural modulus of 0.7×10 ⁴ Kg/cm ² or more and a Rockwell hardness of R130 or less, which is a homogeneous melt blend of two or more thermoplastic resins with different chemical structures. ,
The pen body is made of easy-to-cut plastic, in which the proportion of each thermoplastic resin in the total weight of the material is at least 5% by weight. In the above, a system in which the proportion of each thermoplastic resin is less than 5% by weight does not sufficiently exhibit machinability, and more preferably a system in which the proportion is approximately 10% by weight or more is effective. In addition, a pen body made of a melt-blended material having a bending elastic modulus of 0.7×10 ⁴ Kg/cm ² or more and a Rockwell hardness of R130 or less is more preferable in terms of machinability. In other words, systems with a bending modulus of elasticity of less than 0.7×10 ⁴ Kg/cm ² are deformed by external force when a cutting tool is pressed against them, making it difficult to cut into the desired shape. It is undesirable because it has a large cutting property and a feeling of resistance. In thermoplastic resin, flexural modulus is 0.7×10 ⁴
Kg/cm ² or more and Rockwell hardness of R130 or less, styrene resins and their copolymer resins, vinyl chloride resins and their copolymer resins, nonyl resins, methacrylic resins, polysulfone resins, polyacetal resins, Examples include butylene terephthalate resin, polycarbonate resin, polyamide resin, vinylidene fluoride resin, cellulose resin, polypropylene resin, etc. However, the ease of cutting as in the pen body of the present invention cannot be obtained by using any of these resins alone. A pen body made of a material obtained by homogeneously melting and blending two or more resins selected from the above resin group (hereinafter referred to as the base resin group) is a pen body made of any of the above single resins. Improved machinability can be seen compared to the conventional type. This point will be explained using an example. Comparing a pen body with an ink passage running through the internal axis of a melt-molded polyacetal resin body and a pen body made of a homogeneous melt blend of polyacetal resin and polyamide resin, the former pen body can be used with a pencil sharpener. If you try to sharpen it, the cutting resistance will be large and it will not be possible to cut it, whereas the latter type of pen body can be easily cut with low cutting resistance, making it possible to obtain a sharpened pen body. Even with bladed tools such as knives, the former pen body has high rigidity and caking properties, and the blade has poor penetration and high cutting resistance, making it difficult to cut, whereas the latter pen body is difficult to cut. Good and easy to cut. Similarly, in contrast to a pen body made of a single polyamide resin, a pen body made of a melt blend of polyamide resin and polyacetal resin exhibits easier machinability. Furthermore, in the same way, any system such as styrene resin-polyacetal resin system, polyamide resin-styrene resin system, polyacetal resin-styrene resin system, polybutylene terephthalate resin-polyamide resin system, polybutylene terephthalate resin-styrene resin system, etc. However, it shows easier machinability compared to single resin systems. Furthermore, systems of combinations of three different resins, e.g.
Polyacetal resin-polyamide resin-styrene resin system, polyamide resin-methyl methacrylate resin-vinyl chloride resin system, polybutylene terephthalate resin-polyamide resin-polyacetal resin-styrene resin copolymer (e.g.
(AS resin, ABS resin, etc.) also exhibits easier machinability compared to any single resin pen body. Furthermore, the present invention uses polyester elastomers, polyurethane elastomers, polyethylene resins, and ethylene-vinyl acetate copolymers that have a flexural modulus of less than 0.7×10 ⁴ Kg/cm ² and are deformed by cutting pressure and difficult to sharpen into a desired shape. A homogeneous product obtained by melt-blending one or more types selected from a group of resins (referred to as auxiliary resin group) such as polymer resins, vinylidene chloride resins, and synthetic rubber resins with one or more types selected from the base resin group. A pen body formed from compatible materials can be easily cut, which cannot be achieved with a single resin system of this kind of auxiliary resin group. A supplementary explanation will be given below by illustrating some aspects. (1) A pen body that is hard and easy to cut can be obtained by combining two or more resins selected from the base resin group, and can be made easier by blending a resin selected from the auxiliary resin group. You can change the writing style without damaging it. (2) In order to be hard, have characteristics for fine writing, and have good cutting properties with a pencil sharpener, etc., the bending elastic modulus is preferably in the range of approximately 1.5×10 ⁴ Kg/cm ² or more. (3) The pen body, which is hard, wear-resistant, and easy to cut, is mainly made of base resins such as polyacetal resin, polyamide resin, polybutylene terephthalate resin, etc., and these resins can be blended with each other or mixed as necessary. Add auxiliary resins such as polyethylene resin, polyurethane elastomer, and polyester elastomer. At this time, in the blend within the base resin group, when each resin accounts for at least 5% by weight or more, preferably 10% by weight or more, the machinability effect is effectively exhibited. (4) Taking advantage of the hardness and rigidity of styrene resin,
In order to obtain a pen body that is more wear resistant and easier to cut than this type of resin alone, abrasion resistant resins such as polyamide resin, polyacetal resin, and polyethylene resin are blended. . (5) In order to obtain a pen body that is relatively soft and can be used as an art material and easily shaped into any desired shape by cutting, the blending ratio of resins selected from the group of auxiliary resins should be increased. (In this case, a range that satisfies the bending elastic modulus of 0.7×10 ⁴ Kg/cm ² or more is preferable.) Production example (1) Preparation of melt blend material Melt homogeneously at a temperature higher than the melting point of each resin used for blending. Obtained by blending.

[Table] The above resins were mixed in a blender at room temperature, then put into an extrusion molding machine, kneaded and extruded at about 190°C to form continuous rods, and pelletized with a pelletizer. In addition, parts in the above formulation examples indicate parts by weight (the same applies below). As the resin used for blending, appropriate resins such as pellets and powders are effective.

[Table] A melt-blended material of each of the above resins was produced according to the above Preparation Example.

[Table] *3 Mitsubishi Monsanto Chemical Co., Ltd. “Toughflex”
261”
*4 Toyobo Co., Ltd. “Pelprene P150B”
A melt-blended material of each resin having the above formulation was produced according to the above Preparation Example. (However, the kneading and extrusion temperature is approximately 220℃)

[Table] A melt blended material having the above formulation was produced according to the above Preparation Example. (However, the kneading and extrusion temperature is approximately 240℃)

[Table] A melt blended material having the above formulation was produced according to the above Preparation Example. (However, the kneading and extrusion temperature is approximately 240°C) (2) Example of manufacturing a pen body The above-mentioned melt-blended materials (material groups 1 to 5)
(Group) using the manufacturing method described in Japanese Patent Publication No. 49-2132 and Japanese Patent Publication No. 53-27973 (a process in which a molten thermoplastic resin is A plurality of filaments are formed by extrusion, and the filaments are brought into contact and fused with each other in a state where the surfaces of the filaments have fusion properties, and a space that becomes an ink conduction path is formed in the axial direction without contacting or fusion bonding. Figure 1,
Pen bodies of 3 mmφ and 7 mmφ with the cross-sectional shapes shown in FIG. 2 were obtained. Performance test method and test results (1) Cut sample and cutting tool The molded body with an outer diameter of 7 mmφ was cut into appropriate lengths and used as a cut sample, and the molded body with an outer diameter of 7 mmφ was cut into a low-foaming sample with an outer diameter of 7 mmφ. It was inserted into the center of an ABS resin rod and used as a cutting sample. As cutting tools, a commercially available electric pencil sharpener (National KP-56) and knife (NT Cutter A-300) were used. In addition, as a comparative sample,
A pen body made of a single resin such as styrene resin, methacrylic resin, polyacetal resin, polybutylene terephthalate resin, or polyamide resin with the same outer diameter and cross-sectional shape as the sample was manufactured, processed in the same way, and used as a sample. . (2) Test Results The cut sample of the present invention could be sharpened smoothly with a pencil sharpener and easily sharpened with a knife. By cutting the tip with a knife, it was possible to create various shapes. On the other hand, the comparative samples had too much cutting resistance with a pencil sharpener, and the motor did not drive smoothly.
It was not possible to obtain a sharpened pen body. Moreover, the cutability (penetration) with a knife was poor, and it was extremely difficult to form a sharp point, and the above-mentioned shaping process was also difficult. Effects of the Invention As seen in the above test results, the pen body of the present invention can be easily cut into various shapes using various cutting tools, and when the writing tip changes to a wide width due to wear, it does not become sharp. You can write fine print continuously,
If used as a pen tip for illustrations, art supplies, etc.
Users can cut it into various shapes according to their purposes and use it for practical purposes. In addition to being easy to cut, the pen body is made of a material that is a homogeneous melt blend of different resins, so it has a variety of writing tastes and abrasion properties that cannot be achieved with a pen body made of a single resin. We can provide a unique pen body. As a specific application example of the pen body of the present invention, for example, in a felt-tip pen, the neck barrel is made of low-foamed ABS resin.
If the pen body of the present invention is assembled by inserting the pen body of the present invention into the neck tube and is made of an easy-to-cut material such as low-foamed polyolefin resin, when the writing tip becomes thicker due to wear, it can be used with a pencil sharpener or The writing tip can be easily cut to its original sharp state with a cutting tool such as a knife, and the pen can satisfy its practicality as a fine writing felt-tip pen.

[Brief explanation of drawings]

FIGS. 1 and 2 are sectional views of specific examples of the pen body of the present invention. 1...Pen body, 2...Ink conduction path.

Claims (1)

[Claims] 1. In a plastic pen body formed by extrusion molding of a thermoplastic resin and having an ink passage extending through the molded body in the internal axial direction, two or more thermoplastic resins having different chemical structures are homogeneously formed. It is molded from a melt-blended homogeneous compatible material with a flexural modulus of 0.7×10 ⁴ Kg/cm ² or more and a Rockwell hardness of R130 or less, and the proportion of each thermoplastic resin in the total weight of the material is at least An easily cuttable plastic pen body characterized by having a content of 5% by weight. 2 Styrene resin and its copolymer resin, vinyl chloride resin and its copolymer resin, nonyl resin, methacrylic resin, polysulfone resin, polyacetal resin, polybutylene terephthalate resin, polycarbonate resin, polyamide resin,
Two or more resins selected from the resin group vinylidene fluoride resin, cellulose resin, and polypropylene resin are homogeneously melt-blended, or one or more resins selected from the resin group are combined with polyester elastomer, polyurethane elastomer, A patent claim made of a homogeneous compatible material obtained by homogeneously melt-blending one or more resins selected from the group of resins polyethylene resin, ethylene-vinyl acetate copolymer resin, vinylidene chloride resin, and synthetic rubber resin. The easy-to-cut plastic pen body according to item 1.