WRITING INSTRUMENT PART, METHOD FOR MANUFACTURING WRITING INSTRUMENT PART, AND WRITING INSTRUMENT

Abstract

A writing instrument part that improves the releasability of a core pin is provided. In a writing instrument part by the insert molding method in which a wooden barrel material made of natural wood flour and a water-soluble resin binder is injected into a mold, the wooden barrel material and a core pin having a paper straw inserted therein are integrated, and a two-layer structure having a paper straw layer as an inner layer and a wooden barrel layer as an outer layer is formed.

Claims

1. A writing instrument part is wherein a part in which a wooden barrel material and a core pin in which a paper straw is inserted are integrally molded by insert molding in which the wooden barrel material composed of wood flour and a binder of water-soluble resin is injected into a mold and a two-layer structure having a paper straw layer on an inner layer and a wooden barrel layer on an outer layer is formed by releasing the core pin.

2. The writing instrument part according to claim 1, wherein the wood flour is a powder of cedar, cypress, bamboo, or cork.

3. The writing instrument part according to claim 1, wherein the binder is cellulose or a cellulose derivative.

4. The writing instrument part according to claim 1, wherein the paper straw is biodegradable.

5. A method of manufacturing a writing instrument part, comprising the steps of: forming a space having the shape of a writing instrument part by setting a core pin to which a paper straw is attached in a mold; injecting a wooden barrel material composed of wood flour and a binder which is a water-soluble resin into the space from a mold spout provided in the mold; producing a first molded article in a state in which the wooden barrel material and the core pin are integrally formed by insert molding by removing the mold after injection; and obtaining a writing instrument part having a two-layer structure with a paper straw layer on the inner layer and a wooden barrel layer on the outer layer, by heating the first molded article to harden and releasing the core pin from the second molded article, which is the heated first molded article.

6. The method of manufacturing a writing instrument part according to claim 5, wherein a gate is formed in the mold, connected to the mold spout as a storage space for the wooden barrel material, the gate is provided circumferentially on the outer periphery of the core pin between the mold spout and the space, the writing instrument part having a two-layer structure is obtained by releasing the core pin from the second molded article and cutting off an excess portion formed in a shape of the gate.

7. The method of manufacturing a writing instrument part according to claim 5, wherein the heating of the first molded article is carried out under the condition of a temperature of 150 C. for one (1) hour.

8. The method of manufacturing a writing instrument part according to claim 5, wherein the wood flour is a powder of cedar, cypress, bamboo, or cork.

9. The method of manufacturing a writing instrument part according to claim 5, wherein the binder is cellulose or a cellulose derivative.

10. The method of manufacturing a writing instrument part according to claim 5, wherein the paper straw is biodegradable.

11. A writing instrument, comprising a writing instrument part according to claim 1.

12. A writing instrument, comprising a writing instrument part manufactured by the method of manufacturing a writing instrument part according to claim 5.

13. A writing instrument, comprising a writing instrument part according to claim 2.

14. A writing instrument, comprising a writing instrument part according to claim 3.

15. A writing instrument, comprising a writing instrument part according to claim 4.

16. A writing instrument, comprising a writing instrument part manufactured by the method of manufacturing a writing instrument part according to claim 6.

17. A writing instrument, comprising a writing instrument part manufactured by the method of manufacturing a writing instrument part according to claim 7.

18. A writing instrument, comprising a writing instrument part manufactured by the method of manufacturing a writing instrument part according to claim 8.

19. A writing instrument, comprising a writing instrument part manufactured by the method of manufacturing a writing instrument part according to claim 9.

20. A writing instrument, comprising a writing instrument part manufactured by the method of manufacturing a writing instrument part according to claim 10.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0024] FIG. 1 is a view illustrating an example of the configuration of a writing instrument according to the present invention.

[0025] FIG. 2 is a view illustrating an example of the configuration of a front barrel which is one of the writing instrument parts according to the present invention.

[0026] FIG. 3 is a view illustrating an example of a member for manufacturing which is to be used in the method of manufacturing the writing instrument part according to the present invention.

[0027] FIG. 4 is an exploded block structural view of a manufacturing member to be used in the method of manufacturing the writing instrument part according to the present invention and a manufactured writing instrument part.

[0028] FIG. 5 is a view illustrating an example of a method of manufacturing the writing instrument part according to the present invention.

[0029] FIG. 6 is a view illustrating an example of a method of manufacturing the writing instrument part according to the present invention.

[0030] FIG. 7 is a view illustrating an example of a method of manufacturing the writing instrument part according to the present invention.

[0031] FIG. 8 is a view illustrating an example of a method of manufacturing the writing instrument part according to the present invention.

[0032] FIG. 9 is a view illustrating an example of a method of manufacturing the writing instrument part according to the present invention.

[0033] FIG. 10 is a view illustrating an example of a method of manufacturing the writing instrument part according to the present invention.

[0034] FIG. 11 is a view illustrating an example of a method of manufacturing the writing instrument part according to the present invention.

DESCRIPTION OF EMBODIMENTS

[0035] A writing instrument part according to the present invention, a method of manufacturing the writing instrument part, and a writing instrument will be described in detail below with reference to the drawings. However, the present invention is not limited to these embodiments. In some cases, components that can be described similarly in the description and drawings of the present invention will be referred to by the same reference signs, and duplication of description will be omitted.

Configuration of Writing Instruments

[0036] FIGS. 1A to 1C are views illustrating an example of the configuration of a writing instrument according to the present embodiment, and FIG. 1A is a front view of the external appearance of the writing instrument, 1B is a cross-sectional view of the writing instrument, and 1C is a perspective view of the writing instrument. In the present embodiment, the configuration of a ballpoint pen is described as an example of a writing instrument.

[0037] A ballpoint pen 1 (writing instrument 1) according to the present embodiment has a barrel 2 having an approximately cylindrical shape and accommodates a refill 3 in the barrel 2. The barrel 2 is composed of a wooden barrel tip 4, a front barrel 5, and a rear barrel 6 in the order described from the tip end from which a ballpoint pen tip 3a protrudes which is part of the refill 3. The wooden barrel tip 4, the front barrel 5, and the rear barrel 6 are formed as writing instrument parts (barrel members) of the present embodiment by injection molding in which the wooden barrel material made of wood flour, a natural material, as a base material (main component) is injected into a predetermined mold. As for the barrel 2, the rear end of the wooden barrel tip 4 and the front end of the front barrel 5, and the rear end of the front barrel 5 and the front end of the rear barrel 6 are detachably fitted, respectively.

[0038] As described above, the refill 3 to be accommodated in the barrel 2 is provided with a long thin cylindrical ink reservoir 3b storing ink, a joint member 3c attached to the tip end of the ink reservoir 3b, and a ballpoint pen tip 3a attached to the tip end of the joint member 3c.

[0039] In FIG. 1B, the ballpoint pen 1 has a structure in which the upper surface 4a, the periphery of the opening, of the rear end of the wooden barrel tip 4 and the locking member 5a provided on the inner periphery near the tip end of the front barrel 5 sandwich the flange portion 3d, or the flange portion 3d provided on the joint member 3c, provided on the outer periphery of the refill 3, for receiving the writing pressure.

Configuration of Writing Instrument Part

[0040] FIGS. 2A to 2F are views illustrating an example of the configuration of the front barrel, which is one of the writing instrument parts according to the present embodiment; FIG. 2A is a front perspective view, FIG. 2B is a rear perspective view, FIG. 2C is a bottom view, FIG. 2D is a plan view, FIG. 2E is a front view, and FIG. 2F is a front cross-sectional view, respectively.

[0041] As shown in FIGS. 2A to 2F, the front barrel 5 has a penetrating hole 5b provided so that the ink reservoir 3b of the refill 3 can be inserted therethrough, and has a configuration in which a connecting portion 5c formed into an approximately cylindrical shape as a rear end portion to which the rear barrel 6 is connected by press-fitting, a cylindrical portion 5d formed into an approximately cylindrical shape having a larger outer diameter than the connecting portion 5c, and a tapered portion 5e tapered toward the tip end having a tip end opening (the tip end of the penetrating hole 5b) to be press-fitted to the wooden barrel tip 4, are connected.

[0042] In addition, the front barrel 5 is provided with an inner layer 5f of the paper straw (the paper straw layer 5f) in close contact with the wall surface of the penetrating hole 5b. That is, the front barrel 5 forms a two-layer structure together with the wooden barrel layer constituting the outer layer (the layer composed of the connecting portion 5c, the cylindrical portion 5d and the tapered portion 5e). The paper straw layer Sf is provided for the purpose of improving the releasability of the core pin described later. The material of the paper straw may be any tubular material made by agglomeration of plant fibers or other fibers, as long as it does not stick to the core pins when molded below 150 C. and integrates (including tightening and bonding by shrinkage) with the wood barrel material after drying. The wall thickness of the paper straw is preferably 0.2 mm to 2.0 mm.

Preferable Wooden Barrel Materials

[0043] For writing instrument parts according to the present embodiment, the preferred wooden barrel material will be described.

[0044] The wooden barrel material is composed of wood flour as a natural material and a water-soluble resin as a binder, for example, and the compounding ratio of the wood flour and the binder is preferably 9:1 to 6:4, and further preferably 9:1 to 7:3.

[0045] Sawdust from coniferous trees such as cedar, cypress, or pine tree, or from deciduous trees such as beech, oak, or sawtooth oak, or cork or bamboo powder can be used as wood flour, preferably with a particle size of less than 3 mm to obtain better surface properties. When the particle size is 3 mm or more, it is undesirable because there may be irregularities on the surface of parts due to particles. Furthermore, the particle size of the wood flour is preferably 0.1 mm or more to prevent it from distorting during drying. When the particle size is less than 0.1 mm, it is undesirable because the pathways for moisture are likely to be closed during shrinkage during drying, and the wooden barrel material may be distorted so that a proper shape cannot be obtained.

[0046] As binders, water-soluble or hydrophilic substances are preferable, such as cellulose, cellulose derivatives (carboxymethyl cellulose, ammonium carboxymethyl cellulose, sodium carboxymethyl cellulose, methylcellulose), sodium alginate, polyvinyl alcohol, polyoxyethylene, polyacrylamide, copolymerized maleic acid resin.

Method of Manufacturing

[0047] Next, a method of manufacturing a writing instrument part according to the present embodiment will be described in detail. In the present embodiment, as an example of a method of manufacturing a writing instrument part, a method of manufacturing a front barrel 5 will be described, and a wooden barrel tip 4 and a rear barrel 6 can be similarly manufactured.

[0048] FIG. 3 is a view illustrating an example of a member for manufacturing which is to be used in the method of manufacturing the writing instrument part according to the present embodiment. FIG. 4 is an exploded block structural view of a manufacturing member to be used in the method of manufacturing the writing instrument part according to the present embodiment and a manufactured writing instrument part. As shown in FIG. 3, the front barrel 5 is manufactured by using a mold 11 formed so as to sandwich a first mold 11a and a second mold 11b and a core pin 14 to which a stripper washer 12 and a paper straw 13 are inserted at a predetermined position. Specifically, the core pin 14 (see FIG. 3), which is integrated by inserting the stripper washer 12 and the paper straw 13, is first set in the mold 11 (being sandwiched by the first mold 11a and the second mold 11b), and space for forming the front barrel 5 is made in the mold 11. Then, the front barrel 5 is formed by injecting the wooden barrel material described above through the mold spout 15 provided in the mold 11, i.e., by injection molding.

[0049] FIGS. 5A to 11F are views illustrating an example of the method of manufacturing a writing instrument part according to the present embodiment. The method of manufacturing the front barrel 5 will be more specifically described below with reference to FIGS. 5a to 11F.

[0050] FIGS. 5A and 5B are cross-sectional views of the mold 11 illustrating a state in which the core pin 14, including the stripper washer 12 and the paper straw 13, is placed in the mold 11; FIG. 5A is a front cross-sectional view viewed from the front side of the sandwiching surface, the first mold 11a and the second mold 11b, of the mold 11 and FIG. 5B is a side cross-sectional view viewed from the side of the mold 11. As shown in FIGS. 5A and 5B, the space 16 having the shape of the front barrel 5 (the wooden barrel tip 4, the front barrel 5, the rear barrel 6) is formed by setting the core pin 14 integrated with the stripper washer 12 and the paper straw 13 in the mold 11. In the state in which the core pin 14 is placed, a gate 15a connected to a mold spout 15 is formed in the mold 11 as a storage space for wooden barrel material. The gate 15a is circumferentially provided on the outer periphery of the core pin 14 between the mold spout 15 and the space 16 so that the wooden barrel material injected through the mold spout 15 is uniformly distributed in the space 16 (see FIGS. 5A and 5B).

[0051] In the above state, the wooden barrel material described above is loaded into a molding machine (not shown), and the molding machine pressure feeds the wooden barrel material into the gate 15a through the mold spout 15, and the wooden barrel material stored in the gate 15a is further pressure fed to the space 16. Then, the injection pressure is measured at the molding machine as the wooden barrel material is injected, and the injection is stopped when a sudden increase in pressure is detected (the completely filled state). FIGS. 6A and 6B are cross-sectional views of the mold 11 in a state in which the wooden barrel material is injected into the gate 15a; FIG. 6A is a front cross-sectional view and FIG. 6B is a side cross-sectional view. FIGS. 7A and 7B are cross-sectional views of the mold 11 in a state in which the mold is completely filled with the wooden barrel material; FIG. 7a is a front cross-sectional view and FIG. 7B is a side cross-sectional view.

[0052] After the injection is completed, the mold 11 (first mold 11a and second mold 11b) is removed to obtain a molded article 21 in a state in which the core pin 14 (including the stripper washer 12) and the wooden barrel material, which has entered the space 16 and the gate 15a, are integrated by insert molding. FIGS. 8A and 8B are cross-sectional views illustrating an example of the molded article 21; FIG. 8A is a front cross-sectional view and FIG. 8B is a side cross-sectional view.

[0053] The molded article 21 is then heated in a dryer (not shown) at 150 C. for one hour to harden the wooden barrel material portion shown in FIGS. 8A and 8B. For the molded article 21 after heating, the core pin 14 is pulled out of the hardened wooden barrel material portion (mold releasing) by pushing in the stripper washer 12 (see FIGS. 9A and 9B), and a molded article 21 is obtained in a state in which the front barrel 5 and the excess portion 22 formed in the shape of the gate 15a are integrated (see FIGS. 10A and 10B). By releasing the core pin 14, the front barrel 5 is obtained having a two-layer structure comprising a paper straw layer 5f composed of paper straw 13 on the inner layer and a wooden barrel layer composed of the connecting portion 5c, the cylindrical portion 5d, and the tapered portion 5e on the outer layer. FIGS. 9A and 9B are cross-sectional views illustrating the molded article 21 in a state in which the stripper washer 12 is pushed in; FIG. 9A is a front cross-sectional view and FIG. 9B is a side cross-sectional view. FIGS. 10A and 10B are cross-sectional views of an example of the molded article 21; FIG. 10A is a front cross-sectional view and FIG. 10b is a side cross-sectional view.

[0054] At last, the front barrel 5 formed in a predetermined shape is obtained by cutting the excess portion 22 formed in the shape of the gate 15a (final process). FIGS. 11A to 11F are views illustrating the final process; FIG. 11A is a front perspective view, FIG. 11B is a rear perspective view, FIG. 11C is a front view, FIG. 11D is a front cross-sectional view, FIG. 11E is a side view, and FIG. 11F is a side cross-sectional view.

[0055] In the present embodiment, the method of manufacturing a writing instrument part as an example of barrel material including the wooden barrel tip 4, the front barrel 5, and the rear barrel 6 constituting the barrel 2 of the ballpoint pen 1, it is not limited to the embodiment and the manufacturing method can be applied to any writing instrument having a barrel material which can be manufactured by injection molding.

Advantageous Effects

[0056] As described above, for example, the writing instrument parts of this embodiment are manufactured by insert molding, in which a wooden barrel material composed of wood flour, a natural material, and a binder, a water-soluble resin, is injected into the mold 11 to integrate the wooden barrel material and the core pin 14 into which the paper straw 13 is inserted, and then the core pin 14 is released, thereby forming a two-layer structure having a paper straw layer 5f on the inner layer and a wooden barrel layer (layers of connecting portion 5c, cylindrical portion 5d, and tapered portion 5e) on the outer layer.

[0057] In the manufacturing method of the writing instrument parts of the present embodiment, the space 16 having the shape of the writing instrument part is first formed in the mold 11 by setting the core pin 14 to which the paper straw 13 is attached. Then, the wooden barrel material composed of wood flour and a binder which is a water-soluble resin is injected into the space 16 through the mold spout 15 provided on the mold 11. After the injection is completed, the mold 11 is removed and the molded article 21 is manufactured in the state in which the wooden barrel material and the core pin 14 are integrated by insert molding. Then, by heating the molded article 21 to harden and releasing the core pin 14 from the heated molded article 21, the writing instrument part having the two-layer structure with the paper straw layer 5f on the inner layer thereof and the wooden barrel layer on the outer layer thereof is obtained.

[0058] Thus, the core pin 14 is made slippery by the paper straw layer 5f, which is the paper straw 13, and the releasability when the core pin 14 is pulled out can be greatly improved.

INDUSTRIAL APPLICABILITY

[0059] As described above, the writing instrument part and the method of manufacturing the writing instrument part according to the present invention are useful as one of the endeavors to global environmental problems such as reducing the use of plastics.

LIST OF REFERENCE SIGNS

[0060] 1 ballpoint pen (writing instrument) [0061] 2 barrel [0062] 3 refill [0063] 3a ballpoint pen tip [0064] 3b ink reservoir [0065] 3c joint member [0066] 3d flange portion [0067] 4 wooden barrel tip [0068] 4a upper surface [0069] 5 front barrel [0070] 5a locking member [0071] 5b penetrating hole [0072] 5c connecting portion [0073] 5d cylindrical portion [0074] 5e tapered portion [0075] 5f inner layer (paper straw layer) [0076] 6 rear barrel [0077] 11 mold [0078] 11a first mold [0079] 11b second mold [0080] 12 stripper washer [0081] 13 paper straw [0082] 14 core pin [0083] 15 mold spout [0084] 15a gate [0085] 16 space [0086] 21 molded article [0087] 22 excess portion