JP6567902B2 - Tip body and method for producing the same - Google Patents

Description

  The present invention relates to a tip and a method for manufacturing the same for writing or applying an ink or a coating liquid to a desired location.

  The applicator is typically a writing instrument, marker or the like, and generally includes an ink tank filled with ink (coating liquid) in a shaft cylinder (gripping cylinder) or a coating liquid occlusion body impregnated with ink. Connect the rear end of the tip body to the tank or coating solution occlusion body directly or via a relay core (induction core), and connect the tip of the tip body to the shaft of the applicator (some types have a tip holder). The structure is exposed to the outside.

  The tip is for writing letters, figures, symbols, etc. The tip of the tip is sharp, bullet-shaped, hemispherical, flat, straight edge or inclined depending on the application. There are those formed on the edge (chisel shape) or the like. Conventionally, the method of manufacturing the tip body is a method in which plastic fibers are bundled in a rod shape, a short fiber is impregnated with a thermosetting resin or a thermoplastic resin and heat-cured to form a fiber aggregate, or a plastic extrusion molding In addition, a porous body made by plastic sintering is known.

  For example, Patent Document 1 describes a pen core having a two-layer structure including a pen core tip portion made of fine particles and a pen core root portion made of coarse particles. In this method for producing a pen core, first, a polyvinylidene fluoride resin powder having an apparent specific gravity of 0.35 is preliminarily heated in flowing air at 240 to 250 ° C. to obtain a baked polymer. The fired polymer is divided into an average particle size of about 200 μm and an average particle size of 100 μm, and a pen core mold is first filled with a fired polymer with an average particle size of 100 μm, and then a fired polymer with an average particle size of about 200 μm. Fill. And after making it sinter in 250 degreeC fluid air, it cools and a pen core is shape | molded by releasing from a pen core metal mold | die.

  Patent Document 2 describes a tip body composed of a porous tip body made of a synthetic resin and a batting incorporated in the tip body. The tip body of the tip body is made of a synthetic resin sintered body, and is entirely molded with the same porosity.

Japanese Patent Publication No.49-32969 JP 2014-83699 A

  However, in the pen core manufacturing method described in Patent Document 1, the tip of the pen core is formed by sintering a sintered polymer having an average particle diameter of 100 μm, and thus has a low porosity. For this reason, there exists a possibility that it cannot write or apply | coat to a desired location fully. Even if characters, figures, symbols, etc. can be written, there is a possibility that a person behind the room cannot read in a conference room, a lecture hall, a large classroom, or the like.

Moreover, since the pen core root part of the pen core described in Patent Document 1 is formed by sintering a sintered polymer having an average particle diameter of 200 μm, the porosity is high. For this reason, when the pen core is attached to the holder of the applicator, the holding force to the holder is weak, and by applying external force such as bending of the pen core due to writing pressure or vibration, impact during transportation to the applicator, There is a possibility that problems such as the applicator coming off from the holder or floating may occur.

  Furthermore, in the tip body described in Patent Document 2, by incorporating the batting in the tip body formed entirely with the same porosity, the coating liquid can be sufficiently supplied and can be applied widely. Patent Document 2 does not disclose that the tip body is formed in a two-layer structure.

  The present invention has been made in view of the above points, and provides a tip body that can sufficiently supply a coating liquid and can be applied widely, and further has improved holding power to a holder of an applicator, and a method for manufacturing the same. The purpose is to provide.

According to the present invention, as means for solving the above-mentioned problems, the invention described in claim 1 is to attach ink supplied from a coating liquid occlusion body mounted in a holder of the applicator to the holder of the applicator. A rod-shaped tip body, the tip body having a storage hole opened at a rear end, a tip body made of a synthetic resin sintered body having a writing end as a writing end, and a batting inserted into the storage hole The tip body is a layer with a high porosity at the writing end, a portion for holding the tip body in the holder is a layer with a low porosity, and the storage hole provided in the tip body is the writing hole. It extends to the inside of the end, the batting fills the storage hole, the rear part reaches or protrudes to the opening of the storage hole, and the tip body has a layer having a high porosity and a layer having a low porosity. And a flange portion having the same porosity as the low layer Made is, the flange portion is characterized in that a plurality of air exchange grooves which are disposed at predetermined intervals is formed.

  The tip body according to this section is configured in a two-layer structure including a layer having a high porosity (tip portion, that is, a writing end) and a layer having a porosity lower than that of the layer having a high porosity (body portion and flange portion). In addition, since the inside of the writing end of the tip body has a rod-like filling, the ink is sufficiently supplied to the writing end even if the body portion and the flange portion have no porosity. Can do. In addition, the ink supply at the writing end is good, the softness (soft touch feeling) is provided, the body part is rigid, and the tip of the tip body is very little bent due to the writing pressure. The phenomenon that the body gradually goes outward can be prevented.

In addition, the tip body according to this section prevents the tip body from sinking into the holder by providing an annular flange portion extending radially outward between the layer having a high porosity and the layer having a low porosity. In addition, by providing a plurality of air exchange grooves in the flange portion, air can be exchanged smoothly in the ink tank or the coating liquid storage body.

The invention described in claim 2 is the invention described in claim 1, wherein the low porosity layer extends from the lower surface of the flange portion to the vicinity of the center portion, and is arranged at a predetermined interval. A protrusion is formed.

In the tip body according to this section, a layer having a low porosity is provided with a plurality of protrusions extending from the lower surface of the flange portion to the vicinity of the center portion, and a resin layer (a layer having a low porosity) having a low porosity around this periphery. As a result, the tip body and the holder are firmly fitted, and the tip body from the holder of the applicator can be bent even if external force such as bending of the tip body due to writing pressure or vibration or impact during transportation is applied to the applicator. Can be prevented from coming off and floating.

Also, when mounting the tip member to the holder, a space between the protruding portion and the protruding portion in communication with the air exchange groove (air exchange passage) becomes a passage of air, air exchange groove and the ink tank or the coating liquid An occlusion body can be communicated appropriately.

  In the invention described in claim 4, the core pin is installed in the cavity of the mold, leaving a space around the core pin, and the ultrahigh molecular weight polyethylene powder is not covered at least at the tip of the core pin. A first filling step for filling the cavity, and mixing the ultrahigh molecular weight polyethylene powder and 50 to 80 mass percent of a water-soluble inorganic substance on the ultrahigh molecular weight polyethylene powder filled in the cavity A second filling step for filling the powder, a pressing step for pressing the ultrahigh molecular weight polyethylene powder and the mixed powder with a push pin provided in the die, and heating the die, A sintering step of sintering the high molecular weight polyethylene powder and the mixed powder to form a sintered product, and washing the formed sintered product to remove water-soluble inorganic substances from the sintered product. A soluble inorganic cleaning removal step, a batting insertion step of inserting a rod-shaped filling the molded article removing the water-soluble inorganic substance, a method characterized in that it consists of.

In the method of manufacturing the tip body according to this section, first, the core pin is installed in the cavity of the mold, leaving a space around the core pin (core pin installation step). Next, the ultra high molecular weight polyethylene powder is filled in the cavity without covering at least the tip of the core pin (first filling step), and then the ultra high molecular weight polyethylene powder is filled on the filled ultra high molecular weight polyethylene powder. The mixed powder obtained by mixing the body and 50 to 80 mass percent of the water-soluble inorganic substance is filled (second filling step). Next, the ultrahigh molecular weight polyethylene powder and the mixed powder body are pressurized with a push pin (pressurizing step). Next, the mold is heated to sinter the ultra-high molecular weight polyethylene powder and the mixed powder body (sintering process), and then the obtained sintered product is washed to remove water-soluble inorganic substances from the sintered product. (Water-soluble inorganic substance washing and removing step) to obtain a molded article (tip body). And a batting is inserted in the obtained head main body (batting insertion process).
By this method, the center position can be easily determined by installing the core pin in the cavity of the mold in the core pin installation step. In the first and second filling steps to the sintering step, after the ultra high molecular weight polyethylene powder is filled in the cavity, the ultra high molecular weight polyethylene powder and 50 to 80 mass percent of the water-soluble inorganic substance are mixed thereon. A sintered product can be obtained by filling the powder, pressurizing with a pressing pin, and maintaining the pressurized state and sintering. Thereafter, in the removal step, the water-soluble inorganic substance is removed by washing the sintered product, and a two-layer molded product (tip body) molded with different porosity can be obtained.

  According to the cap of the present invention, it is possible to provide a tip body that can sufficiently supply a coating liquid and can be applied widely, and that has enhanced holding power to the holder of the applicator, and a method for manufacturing the same.

It is a top view in the state where the tip object concerning this embodiment was equipped in the applicator. It is a top view of the tip body shown in FIG. It is a bottom view of the tip body shown in FIG. It is sectional drawing which follows the AA line of the tip body shown in FIG. It is a perspective view of the tip body shown in FIG. It is the figure which showed the process of the manufacturing method of the tip shown in FIG. It is a chart which shows the synthetic resin material which molds the tip object concerning this embodiment, and evaluation.

Hereinafter, the configuration of the tip body 1 according to an embodiment of the present invention will be described in detail with reference to FIGS.
A tip body 1 according to an embodiment of the present invention includes a tip body 11 and a batting 13 built in the tip body 11, and a holder 5 of an applicator 3 containing an ink occlusion body or a coating liquid occlusion body 9. The ink or coating liquid is written or coated on paper, whiteboard or the like.

The material of the tip main body 11 is a substantially bottomed cylindrical porous body made of synthetic resin, and in particular, ultrahigh molecular weight polyethylene is used. The ultra high molecular weight polyethylene is a powder having an average molecular weight of 3.9 million to 5,000,000, preferably an average molecular weight of about 450, an average particle size of 85 μm to 150 μm, and preferably an average particle size of about 115 μm. In the present embodiment, ultra high molecular weight polyethylene (GUR2122, GUR4120) manufactured by Ticona under the trade name GUR (registered trademark) is used. Specifically, Ticona's GUR2122 is a powder having an average particle size of 115 μm, an average bulk specific gravity of 0.23 g / cm ³ , an average porosity of 70%, and an average strength of 1 MPa, and Ticona's GUR4120 has an average particle size of 120 μm. , An average bulk specific gravity of 0.40 g / cm ³ , an average porosity of 40%, and an average strength of 2.5 MPa. Further, as the shape of the ultra high molecular weight polyethylene powder, Ticona's GUR2122 has a kitchen shape, and Ticona's GUR4120 has a potato shape. In the present embodiment, when the tip main body 11 is molded, a powder obtained by adding a water-soluble inorganic substance such as sodium bicarbonate to an ultrahigh molecular weight polyethylene powder and mixing at room temperature with stirring is used in order to adjust the porosity. As this water-soluble inorganic substance, a powder having an average particle size of 25 μm is used, and the blending ratio is 50 to 80 mass percent by weight.

  As shown in FIGS. 2 to 5, the tip main body 11 has a layer 12 a (first layer) with a high porosity and a layer 12 b (second layer) with a low porosity following this at the tip portion (writing site). (See FIGS. 2 and 3). Even if it says the two-layer structure 12, in the intermediate part which two layers contact | connect, the layer (intermediate layer) which both layers entered and formed was formed. The tip body 11 includes a tip portion 15 (writing end), a body portion 17, and an annular flange portion 19 provided between the writing end 15 and the body portion 17 and extending in the outer circumferential direction. The writing end 15 belongs to the layer 12a having a high porosity, and the body portion 17 and the flange portion 19 belong to the layer 12b having a low porosity. Further, the tip body 11 is formed with a columnar accommodation hole 21 extending from the end of the body portion 17 to the vicinity of the approximate center of the writing end 15, that is, the layer 12a having a high porosity (see FIGS. 3 and 4). . In addition, although the flange part 19 is shape | molded in the layer 12b with a low porosity, you may shape | mold in the layer 12a or intermediate | middle layer with a high porosity. In this case, the point where the tip body 1 is mounted inside the holder 5 is required to have a low porosity, that is, a hard part.

  The writing end 15 has a substantially dome shape or a bullet shape, and includes a straight portion 23 extending in a vertical direction from the upper surface of the flange portion 19 and a semicircular portion 25 (a bullet portion). In addition, although the writing end 15 is provided with the straight part 23, only the semicircular part 25 may be sufficient. The trunk portion 17 has a rear end (an end opposite to the writing end 15) having a reduced diameter, extends downward from the lower surface of the flange portion 19 in the axial direction, and is provided with a plurality of intervals along the circumferential direction. A substantially rectangular protrusion 27 is formed (see FIG. 3). Since the plurality of protrusions 27 are hard portions with a low porosity, when the tip body 1 is attached to the applicator 3, it is securely fitted to the inner peripheral surface of the holder 5 of the applicator 3 (FIG. 1). reference). Further, a passage 29 serving as an air exchange passage is formed between the projecting portions 27 at the two opposing positions, and the air exchange passage 29 communicates with two air exchange grooves 31 described later. It has a role as an air passage for exchanging with the ejected ink. In the present embodiment, six protrusions 27 are formed (see FIG. 3). Note that the number of the protrusions 27 can be changed as appropriate. The protrusion 27 has a rectangular shape when viewed from the bottom, but may have a shape such as a semicircular shape when viewed from the bottom, a quadrangular shape when viewed from the bottom, or an arc shape when viewed from the bottom having a width in the circumferential direction.

The annular flange portion 19 extends radially outward from the lower portion of the straight portion 23 of the writing end 15. The flange portion 15 is formed with an air exchange groove 31 provided at intervals along the circumferential direction for exchanging air with the coating liquid storage body 9. The air exchange grooves 31 are not arranged coaxially with the six protrusions 27, and are formed at two positions with an interval of 90 ° (FIG. 3).
reference). The number of air exchange grooves 31 can be changed as appropriate.

  The batting 13 is the same material as the coating liquid occlusion body 9 used in a conventional writing instrument or the like, and is made of polyester, acrylic, polypropylene, polyethylene, nylon or other fibers having a porosity of about 80 to 90%, crimped An aggregate of the fibers is used. These fiber assemblies (filling 13) have a function of holding abundant coating liquid. Further, the batting 13 is formed in a rod-like body so that it can be easily handled in production, and a binder is applied only to the outer periphery thereof, or in the case of a synthetic resin fiber, a weak heat is applied to weld a part of the outer peripheral fiber. Thus, the rod-shaped body is held. When the batting 13 is formed in a rod shape, the gap formed in the peripheral wall is reduced as much as possible by binder or welding.

Next, the manufacturing method of the tip 1 according to the embodiment of the present invention will be described in detail based on FIG.
First, as shown in FIG. 6A, the jig 47 in which the core pin 45 is integrated is attached to the lower mold 43 of the mold 41 (core pin attaching step). At this time, the core pin 45 is prepared so that the shape of the rod-like batting 13 built in the tip body 11 (see FIG. 4), that is, the diameter, length, etc. of the batting 13 are substantially the same.

  Next, as shown in FIG. 6B, the core pin 45 is installed in the cavity 51 formed in the middle mold 49 of the mold 41 (core pin installation step). At this time, in the middle mold 49, the positioning pins 55 provided in the lower mold 43 are inserted into the positioning holes 53 of the middle mold 49 in order to align the positions of the cavity 51 and the core pin 45. The cavity 51 is formed larger than the outer diameter of the core pin 45 and is formed so as to exceed the upper end of the core pin 45. As a result, a gap 57 is formed between the core pin 45 and the cavity 51.

  Next, as shown in FIG.6 (c), the space | gap 57 (refer FIG.6 (b)) between the core pin 45 and the cavity 51 is filled with the ultra high molecular weight polyethylene powder 59 (1st filling process). At this time, the ultra high molecular weight polyethylene powder 59 is filled so as not to exceed the upper end surface (tip portion) of the core pin 45. This ultra high molecular weight polyethylene powder 59 uses GUR2122 made by Ticona or GUR4120 made by Ticona, and is filled with powder that has been sieved into a 40 mesh pass. The first filling step corresponds to the body portion 17 and the flange portion 19 of the tip body 11.

  Next, as shown in FIG. 6 (d), a mixture in which ultrahigh molecular weight polyethylene powder and 50 to 80 mass percent of a water-soluble inorganic substance are mixed on the ultrahigh molecular weight polyethylene powder 59 filled in the cavity 51. The powder 61 is filled (second filling step). At this time, the mixed powder 61 is filled until it is flush with the upper end surface 49 a of the middle mold 49. The mixed powder 61 is filled with powder sieved to 40 mesh pass by adding 50 to 80 mass percent baking soda to GUR2122 manufactured by Ticona and mixing at room temperature with stirring. In the second filling step, it corresponds to the writing end 15 of the tip body 11.

Next, as shown in FIG. 6 (e), the inside of the cavity 51 is pressed by a pressing pin 65 having a substantially dome-shaped recess 65 a provided in the upper die 63 by pressing of a press machine (not shown). The ultrahigh molecular weight polyethylene powder 59 and the mixed powder 61 filled in are pressed to obtain a green compact 70 (pressurizing step). At this time, in order to align the push pin 65 of the upper die 63 with the cavity 51 of the middle die 49, the positioning pin 55 of the lower die 43 is inserted into the positioning hole 67 provided in the upper die 63. Further, the mixed powder 61 rises by the pressing of the push pin 65 and fills the recess 65 a of the push pin 65. In addition, by adjusting the pressing force, that is, the pressing force of the pressing pin 65, the density of the ultrahigh molecular weight polyethylene powder 59 and the density of the mixed powder 61 are changed, and the porosity of the tip body 11 is appropriately changed. be able to. Further, the height of the writing end 15 can be changed as appropriate by changing the depth of the recess 65a of the push pin 65.

  Next, as shown in FIG. 6 (f), the ultrahigh molecular weight polyethylene powder 59 and the mixed powder 61 are pressurized and heated by a heating means 69 (for example, an electric furnace) at a heating temperature of 180 ° C. for 20 minutes. The sintered product 71 is obtained by heating and sintering (sintering step). At this time, before heating by the heating means 69, it adheres to the mold 41 and removes dust and the like.

  Next, as shown in FIG. 6G, after the pressurization by the press machine is released and the upper mold 63 is raised, the sintered product 41 is released from the cavity 51 (release process). At this time, the core pin 45 is not released together with the sintered product 71 because the jig 47 is fixed to the lower mold 43. Next, the sintered product 71 released from the mold 41 is washed in order to elute the built-in water-soluble inorganic material to obtain a molded product 73 (tip body 11) (water-soluble inorganic material washing and removing step, Not shown). Then, as shown in FIG.6 (h), the rod-shaped batting 13 is inserted in the accommodation hole 21 opened at the rear end surface of the molded product 73 (the tip body 11), and the tip body 1 is obtained (batting step). .

  As shown in FIG. 1, when the tip 1 manufactured as described above is used to manufacture an applicator, a coating liquid storage body 9 impregnated with a coating liquid such as ink is placed in a shaft cylinder 7 as shown in FIG. 1. The tip 1 is mounted on the holder 5, and the screw part 5 a of the holder 5 and the screw part 7 a of the shaft cylinder 7 are screwed together. At the time of mounting, it is desirable to connect so that the rear end portion of the tip body 1 is embedded in the front end portion of the coating liquid storage body 9.

  In addition, in the manufacturing process of the tip 1, the core pin 45 is filled with the ultrahigh molecular weight polyethylene powder 59 and the mixed powder 61 and sintered. Alternatively, the ultra-high molecular weight polyethylene powder 59 and the mixed powder 61 may be sequentially filled around the padding 13 and sintered.

  According to the tip body 1 according to an embodiment of the present invention, the tip body 11 includes a layer 12a (writing end 15) having a high porosity and a layer 12b in which the porosity is lower or absent than the layer 12a having a high porosity. Since the rod-shaped batting 13 is built up to the inside of the writing end 15 of the tip main body 11, the body portion 17 and the flange portion are formed. Even if there is no void in 17, ink can be sufficiently supplied to the writing end 15. Furthermore, the writing end 15 has a good supply of ink and has a softness (soft touch feeling), and the body portion 17 has a firmness and the bending of the tip body 1 due to the writing pressure is extremely small. It is possible to prevent the tip body 1 from gradually going outward by writing.

  Further, according to the tip body 1 according to one embodiment of the present invention, the tip body 1 is prevented from sinking into the holder 5 by providing the annular flange portion 19 extending radially outward from the lower portion of the writing end 15. In addition, by providing the two air exchange grooves 31 in the flange portion 19, it is possible to smoothly exchange air with respect to the coating liquid storage unit 9.

  Furthermore, according to the tip 1 according to the embodiment of the present invention, the trunk portion 17 is provided with a plurality of protrusions 27 extending from the lower surface of the flange portion 19 to the vicinity of the center portion of the trunk portion 17, and the periphery of the projection portion 27 has a porosity. Since the resin layer is low (layer 12b having a low porosity), the fitting between the tip body 1 and the holder 5 of the applicator 3 is strengthened, and external forces such as vibration and impact during transportation are applied to the applicator 3. In addition, the tip body 1 can be prevented from coming off from the holder 5 of the applicator 3 and floating. When the tip 1 is mounted on the holder 5, the air exchange passage 29 between the two opposing protrusions 27 communicating with the air exchange groove 31 serves as a passage for the air. The exchange groove 31 and the coating liquid storage body 9 can be communicated appropriately.

According to the method for manufacturing the tip 1 according to the embodiment of the present invention, the center position can be easily determined by using the core pin 45 in the core pin installation step (see FIG. 6B). In the first and second filling steps to the sintering step (see FIGS. 6 (c) to (f)), after the ultrahigh molecular weight polyethylene powder 59 is filled in the cavity 51, the ultrahigh molecular weight polyethylene powder and By filling the mixed powder 61 mixed with 50 to 80 mass percent of the water-soluble inorganic substance, pressurizing with the pressing pin 65, and maintaining this state to sinter, the sintered product 71 of the two-layer structure 12 is obtained. Can be obtained. Thereafter, in the water-soluble inorganic material washing and removing step, the water-soluble inorganic material is removed by washing the sintered product 71, and a molded product 71 (tip body 11) composed of the layer 12a having a high porosity and the layer 12b having a low porosity is obtained. be able to. The porosity can be easily changed by the addition amount of the water-soluble inorganic substance and the pushing force of the push pin 65 in the pressing step.

Next, the evaluation test of Examples 1 and 2 and the tip 1 of the target example molded by the above manufacturing method will be described with reference to FIG.
As shown in FIG. 7, in the evaluation test of the tip 1, the holding strength of the tip 1 and the ink followability were evaluated (see Table 1 described later).
The evaluation test of the holding power was evaluated based on the core removal (core removal force) when the tip body 1 was pressed while the tip body 1 was mounted on the holder 5 of the applicator 3.
In the ink followability evaluation test, the ink consumption (goodness of ink flow) was evaluated.

Next, the materials used for Examples 1 and 2 and the tip 1 of the target example will be described.
In Example 1, as a material for the layer 12a (tip portion 15) having a high porosity, that is, as a powder to be filled in the second filling step (see FIG. 6D), TURona GUR2122 (average particle diameter 115 μm, average) A powder having a bulk specific gravity of 0.23 g / cm ³ , an average porosity of 70%, and an average strength of 1 MPa was added with sodium bicarbonate (70 mass percent) as a water-soluble inorganic substance and mixed at room temperature with stirring, and the porosity was The material of the lower layer 12b (the body portion 17 and the flange portion 19), that is, the powder to be filled in the first filling step (see FIG. 6C), without adding Ticona GUR2122 powder to other substances. Using. Using these powders, the tip main body 11 was formed by the above-described manufacturing method. After the tip body 11 was washed and dried, a rod-shaped batting 13 was inserted from the storage hole 21 at the rear end.

In Example 2, as the powder to be filled in the second filling step, a mixed powder obtained by adding sodium bicarbonate (70 mass percent) to Ticona GUR2122 powder and stirring and mixing at room temperature is used. As a powder, GUR4120 (average particle size 120 μm, average bulk specific gravity 0.40 g / cm ³ , average porosity 40%, average strength 2.5 MPa) manufactured by Ticona was used. Using these powders, the tip main body 11 was formed by the above-described manufacturing method. After the tip body 11 was washed and dried, a rod-shaped batting 13 was inserted from the storage hole 21 at the rear end.

  In the target example, the material of the high porosity 12a and the low layer 12b, that is, Ticona is used as a powder to be filled until the second filling step is omitted and the upper end surface 49a of the middle die 49 is flush with the first filling step. A mixed powder obtained by adding sodium bicarbonate (70 mass percent) as a water-soluble inorganic substance to a GUR2122 powder manufactured by a company and stirring and mixing at room temperature was used. Using this powder, the tip main body 11 was formed by the above-described manufacturing method. After the tip body 11 was washed and dried, a rod-shaped batting 13 was inserted from the storage hole 21 at the rear end.

Next, the conditions of the evaluation test and the manufacturing method will be described with reference to Table 1.

  As shown in FIG. 7, the pressure (insertion force) for inserting the tip 1 into the holder 5 of the applicator 3 was 1200 g in Example 1, 1800 g in Example 2, and 200 g in the target example. . In the holding power evaluation test, as shown in FIG. 7, the tip 1 floated from the holder 5 of the applicator 3 at 1500 g in Example 1, 2000 g in Example 2, and 700 g in the target example. . In the ink follow-up evaluation test, in Examples 1 and 2, the ink consumption was 2.8 (g / 100 m) (see Table 1), and equivalent ink follow-up was obtained. The consumption was 2.9 (g / 100 m) (see Table 1), and it was found that the ink followability was better than in Examples 1 and 2. As shown in FIG. 7, the porosity of the entire sintered body 71 (tip body 11) of Example 1 is about 75%, and the porosity of the entire sintered body 71 of Example 2 is about 70%. The porosity of the entire sintered body (tip body) of the target example was about 80%.

  As a result, in Examples 1 and 2 which are the tip body 11 having the two-layer structure, the tip body 1 is firmly held in the holder 5 of the applicator 3, and external forces such as vibration and impact during transportation are applied. 1 was found to prevent the tip 1 from coming off from the holder 5 and floating. In Examples 1 and 2, although the ink flow was slightly inferior to the ink flow of the target example, the ink flow was good as shown in the evaluation results of the ink followability. In the target example, it was found that the ink flow was better than in Examples 1 and 2.

  DESCRIPTION OF SYMBOLS 1 ... Tip body, 3 ... Applicator, 5 ... Holder, 7 ... Shaft cylinder, 9 ... Coating liquid occlusion body, 11 ... Tip body, 12 ... Two-layer structure, 12a ... High porosity layer, 12b ... Porosity Lower layer, 13 ... Filling, 15 ... Tip (writing end), 17 ... Body, 21 ... Storage hole

Claims (3)

A rod-shaped tip attached to the holder of the applicator and for leading out the ink supplied from the application liquid storage body in the shaft cylinder of the applicator,
The tip body is provided with a storage hole opened at the rear end, consisting of a tip main body made of a synthetic resin sintered body with the tip end as a writing end, and a batting inserted into the storage hole,
The tip body is a layer with a high porosity at the writing end, and a portion that holds the tip body in the holder is a layer with a low porosity.
The storage hole provided in the tip body extends to the inside of the writing end, the batting fills the storage hole, and the rear part reaches or projects the opening of the storage hole ,
The tip body is formed between the layer having a high porosity and the layer having a low porosity, and a flange portion having the same porosity as the low layer is formed.
The tip body is characterized in that a plurality of air exchange grooves arranged at predetermined intervals are formed in the flange portion . Low porosity said layer, according to claim 1, characterized in that extending from the lower surface of the flange portion to the vicinity of the central portion, a plurality of projections arranged at predetermined intervals are formed Tip body. A core pin installation step in which the core pin is installed in the cavity of the mold, leaving a gap around the core pin; and
A first filling step of filling an ultrahigh molecular weight polyethylene powder into the cavity without covering at least the tip of the core pin;
A second filling step of filling the ultrahigh molecular weight polyethylene powder filled in the cavity with a mixed powder obtained by mixing ultrahigh molecular weight polyethylene powder and 50 to 80 mass percent of a water-soluble inorganic substance;
A pressing step of pressing the ultrahigh molecular weight polyethylene powder and the mixed powder with a push pin provided in the mold; and
A sintering step of heating the mold, sintering the ultrahigh molecular weight polyethylene powder and the mixed powder, and molding a sintered product;
Washing the formed sintered product and removing the water-soluble inorganic material from the sintered product,
A method for producing a tip body comprising: a batting insert step of inserting a rod-like batting into a molded product from which the water-soluble inorganic material has been removed.

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