JP7769493B2 - Liquid storage member for writing implement, refill for writing implement, and writing implement - Google Patents

Description

The present invention relates to a liquid container for a writing instrument, a refill for a writing instrument, and a writing instrument that uses a paper base material.

For example, refills for writing instruments such as ballpoint pens are produced by press-fitting the ballpoint pen tip, which is the writing element, or a joint that supports the ballpoint pen tip into one end (tip) of the ink reservoir tube, and are used while housed in the barrel of the ballpoint pen.

Ink reservoir tubes have traditionally been made of transparent or translucent plastics such as polypropylene to ensure ease of molding and visibility of the ink level.

In recent years, the issue of microplastics leaking into the ocean has been attracting attention, and there is growing momentum to address global environmental issues, such as by reducing the use of disposable plastics.

Proposals have also been made for the various components that make up writing instruments, focusing on eliminating the use of plastic. Patent Document 1 discloses a writing instrument equipped with a barrel made by spirally molding a composite material made by laminating a synthetic resin or metal such as aluminum, which has barrier properties, onto a paper base material.

To improve water resistance and gas barrier properties, the barrel used in this writing instrument has a structure in which, from the outside, two layers of aluminum foil label paper and liner paper, each with a kraft paper backing, are layered, followed by a polyethylene layer on the inside and then a polyester film with an aluminum vapor-deposited film on the outside.

By using a composite material containing a paper base, this barrel can provide a writing instrument that is low-pollution while maintaining resistance to contents.

Furthermore, Patent Document 2 below discloses a ballpoint pen refill in which an ink reservoir tube molded from plastic such as polypropylene is replaced with an ink reservoir tube containing a paper base material, thereby reducing the amount of plastic used and the impact on the environment. Specifically, the ink reservoir tube has at least three layers composed of a paper base laminate having two layers: an inner layer of a paper base material and an intermediate layer which is a metal layer or a silica vapor deposition layer formed on the outer peripheral surface of the inner layer; and an outer layer of the paper base material formed on the outer peripheral surface of the intermediate layer, and the density of the paper base material of the inner layer is 0.8 g/ ^cm3 or more.

Japanese Unexamined Patent Publication No. 62-70097 Japanese Patent Application Laid-Open No. 2021-16976

As mentioned above, products using paper as a base material are suitable for reducing pollution, and in particular, using materials containing pulp or paper as the base material can provide environmentally friendly products that can serve as an alternative to plastic.

On the other hand, refills for writing instruments such as ballpoint pens are produced by press-fitting a ballpoint pen tip, or a joint supporting the ballpoint pen tip, into the tip of an ink reservoir. In the process of press-fitting a joint or other component into the tip of the ink reservoir, the tip of the ink reservoir is pushed in until it abuts against the locking flange on the joint, as shown in Figure 8, for example. However, if an environmentally friendly paper-based ink reservoir is used instead of the plastic ink reservoir, the pressure from the inside to the outside caused by press-fitting a joint or other component may cause the ink reservoir to tear or the adhesive surface to peel. Furthermore, ink reservoirs for ballpoint pens and other devices, which are often written at a fixed angle, are prone to problems such as dimensional change (deformation) and breakage due to bending and twisting forces, which can cause an unstable writing feel. In other words, compared to plastic ink reservoirs, which have excellent rigidity, there is still room for improvement in terms of durability and reliability.

The present invention was made to solve the above-mentioned problems, and aims to provide a durable and reliable liquid storage member for a writing instrument, a refill for a writing instrument, and a writing instrument, by replacing liquid storage tubes (ink storage tubes) for writing instruments, such as ink storage tubes, which were previously molded using plastic, with liquid storage tubes for writing instruments that contain a paper base, thereby eliminating the use of plastic.

The liquid containing member for a writing instrument according to the present invention is composed of an innermost layer that comes into contact with the liquid, an intermediate layer formed of at least two or more layers, and an outermost layer, and the layers other than the outermost layer are formed as a paper substrate laminate layer in which a metal layer or a silica vapor deposition layer is laminated on the outer surface side of the inner layer formed of a paper substrate, or as a paper substrate layer, and the liquid containing member includes at least one paper substrate laminate layer and one paper substrate layer, and further the outermost layer is formed as a paper substrate layer, and the paper substrate layer has a structure in which a paper substrate laminate formed into a strip-shaped sheet is spirally wound with the inner layer facing inward, and the paper substrate layer has a structure in which a paper substrate formed into a strip-shaped sheet is spirally wound, and the innermost and outermost layers are spirally wound with the peripheral portions of the strip-shaped sheets in contact with each other so as to overlap.

In particular, it is desirable that the intermediate layer have a two-layer structure, and that for the innermost layer and the intermediate layer (layers other than the outermost layer), at least one of the three layers (the innermost layer plus the two intermediate layers) be formed as a layer of the paper substrate laminate.

According to the present invention, it is possible to obtain a highly reliable and durable liquid container that does not easily tear or peel off from the adhesive surface due to the repulsive force caused by overlapping contact points, even when pressure (load) is applied from the inside to the outside to the tip of the liquid container due to press-fitting, for example.

Furthermore, the liquid container for a writing instrument according to the present invention has an adhesive layer, which is a layer of adhesive containing polyolefin resin, between at least one of the layers from the innermost layer to the outermost layer. This increases the strength of the liquid container, thereby providing a certain level of effectiveness in preventing problems such as tearing of the liquid container and peeling of the adhesive surface.

Furthermore, in the liquid container for a writing instrument according to the present invention, the layers forming the intermediate layer are wound in a spiral shape with the peripheral portions of the strip-shaped sheet in contact with each other but not overlapping, or at least one layer is wound in a spiral shape with the peripheral portions in contact with each other but overlapping. As a result, for example, when the layers are wound in a spiral shape with contact but not overlapping, the tube thickness can be reduced, while when the layers are wound in a spiral shape with contact but overlapping, a liquid container for a writing instrument with even greater strength can be obtained.

Furthermore, in the liquid container for a writing instrument according to the present invention, the inner layer and the metal layer of the paper substrate laminate are bonded together with an adhesive containing a polyolefin resin. This results in a liquid container with even greater strength.

Furthermore, in the liquid container for a writing instrument according to the present invention, it is desirable that the paper substrate laminate and the paper substrate are strip-shaped sheets having a width of 4 to 20 mm. Furthermore, it is desirable that the liquid container for a writing instrument according to the present invention have a total length change rate of less than 0.7% after 300 m of writing. Furthermore, it is desirable that the liquid container for a writing instrument according to the present invention have a bending strength of 0.5 N or more when subjected to a load in a state tilted at 60°.

The writing instrument refill of the present invention is characterized by comprising the writing instrument liquid container of the present invention, writing instrument ink contained within the writing instrument liquid container, and a writing instrument.

Furthermore, it is desirable that the writing instrument refill of the present invention has the outer surface of the writing instrument liquid containing member removed until the metal layer or silica vapor deposition layer forming the paper substrate laminate layer is exposed, so that information can be displayed on the metal layer or silica vapor deposition layer.

The writing instrument of the present invention is configured so that the writing instrument refill of the present invention is housed in a barrel, and the barrel contains biomass-derived polyolefin.

The present invention makes it possible to provide a liquid container for a writing instrument, a refill for a writing instrument, and a writing instrument that are highly durable and reliable while eliminating the use of plastic.

1A and 1B are diagrams showing an example of the configuration of a writing instrument refill including a liquid containing member for a writing instrument according to the present invention. FIG. 2 is a diagram showing an example of the layer structure of a liquid containing member according to the present invention. FIG. 3 is a diagram showing an example of the amount of change in the overall length. FIG. 4 is a diagram showing how a load is applied to a staple-refill in a state inclined at 60 degrees. FIG. 5 is a diagram showing an example of a state in which character information is printed on the exposed metal layer or silica vapor deposition layer. FIG. 6 is a diagram showing an example of the configuration of a writing instrument in which a writing instrument refill is housed in a barrel. FIG. 7 is a diagram showing the layer structure of the liquid containing member in Comparative Examples 1 to 3. As shown in FIG. FIG. 8 is a diagram showing a conventional refill.

Embodiments of a liquid container for a writing instrument, a refill for a writing instrument, and a writing instrument according to the present invention will be described in detail below with reference to the accompanying drawings. Note that the present invention is not limited to these embodiments.

<Writing instrument refills>
FIG. 1 shows an example of the configuration of a writing instrument refill including a liquid containing member for a writing instrument according to the present invention, where FIG. 1(a) shows a front view of the appearance of the writing instrument refill, and FIG. 1(b) shows a cross-sectional view of the writing instrument refill taken along the line A-A'.

In Figure 1, for example, a writing instrument refill 10 (hereinafter simply referred to as "refill 10") housed in the barrel of a ballpoint pen comprises a writing instrument liquid containing member 11 (hereinafter simply referred to as "liquid containing member 11"), which is a long, thin, cylindrical ink containing tube made of paper and containing ink (not shown), a joint 12 attached to the tip of this liquid containing member 11, and a ballpoint pen tip 13 attached to the tip of the joint 12 as a writing member.

Specifically, the joint 12 has a cylindrical rear end portion that joins with the liquid container 11, and a cylindrical front end portion with a smaller outer diameter than the rear end portion, with the ballpoint pen tip 13 attached to this front end portion. Furthermore, an adhesive is applied in advance to the rear end portion of the joint 12 to ensure a certain level of bonding strength at the joint with the liquid container 11, and in this state, the front end of the liquid container 11 is press-fitted into the rear end portion of the joint 12 to join the joint 12 and the liquid container 11. This connects the liquid container 11 and the ballpoint pen tip 13 via the joint 12, allowing ink to flow through.

The ballpoint pen tip 13 also contains a spring 13a inside, which presses the writing ball 13b at the tip of the ballpoint pen tip 13 forward. This prevents ink leakage when the pen is not in use.

The configuration of the refill 10 in this embodiment is merely an example and is not limited to the above. For example, as long as the liquid containing member 11 and the ballpoint pen tip 13 are connected so that ink can flow through them, the structure and shape of the joint 12 may differ from that shown in FIG. 1, or a joint may be unnecessary, with the liquid containing member 11 and the ballpoint pen tip 13 being directly connected.

<Ballpoint pen tip details>
Specifically, the ballpoint pen tip 13 having the above structure comprises the writing ball 13b, a holder 13c that holds the writing ball 13b at its tip, and a spring 13a that is a resilient member attached inside the holder 13c and urges the writing ball 13b forward. The holder 13c is made of bismuth-containing ferritic stainless steel with a Vickers hardness of 200 to 450. The rear end of the holder 13c is a cylindrical portion _13c1 , and the tip end of the holder 13c is a tapered portion _13c2 that is frustum-shaped. The inner periphery of the holder 13c is provided with a ball house _13c3 , which is the internal space of the tapered portion _13c2 , a back hole _13c4 , which is a hole that reaches from the rear end of the holder 13c to the vicinity of the ball house _{13c3 ,} and an ink hole _13c5 , which is a hole with a circular cross section that passes through between the ball house 13c3 and the back hole _13c4 .

The writing ball 13b that can be used with the ballpoint pen tip 13 may be made of a cemented carbide alloy primarily composed of tungsten carbide with cobalt, nickel, or chromium as the binder phase, or a sintered ceramic material primarily composed of silicon carbide, zirconia, or alumina. The ball diameter may be any conventional ball between 0.1 mm and 2.1 mm.

The holder 13c, which holds the writing ball 13b that can be used with the ballpoint pen tip 13, is made of a ferritic stainless steel material containing bismuth (Bi). Bismuth has similar properties to lead (Pb), a commonly used additive for machinability, but its ionization tendency is lower than that of lead. Therefore, it is less likely to leach into ink than lead. Unlike harmful lead, it is harmless and has no impact on the environment. Furthermore, the Vickers hardness of the holder material is preferably between 200 and 450. If the Vickers hardness is below 200, the ball seat, which is the contact point, will be significantly worn away by the rotation of the writing ball during writing, making it difficult to continue writing for long periods of time. Furthermore, if the Vickers hardness exceeds 450, it will be difficult to form a tip with a tapered tip. The Vickers hardness is measured at a position 0.2 mm from the outer surface of the holder toward the center. Other measurement methods conform to JIS Z2244.

<Configuration of Liquid Container Member>
The liquid containing member 11 according to this embodiment is composed of a first layer, which is the innermost layer that comes into contact with the liquid, second and third layers, which are intermediate layers, and a fourth layer, which is the outermost layer, and a layer 21 of adhesive containing a polyolefin resin (hereinafter simply referred to as "adhesive layer 21") is provided between at least one of the layers (between the first and second layers, between the second and third layers, and between the third and fourth layers). Note that Figure 1(b) shows, as an example, a case in which adhesive layers 21 are provided between all layers.

Figure 2 is a diagram showing an example of the layer structure of a liquid containing member according to the present invention. As described above, the liquid containing member 11 of this embodiment is composed of four layers, from layer 1 to layer 4. For example, the outermost layer, layer 4, is formed as a paper substrate layer. Furthermore, for layers 1 to 3, which are the innermost and middle layers, at least one of these layers is a paper substrate laminate, which is formed as a composite material in which a metal layer or a silica vapor deposition layer is laminated on the outer surface side of the inner layer formed as a paper substrate layer. In other words, if any one of layers 1 to 3 is a paper substrate laminate, the remaining two layers are formed as paper substrate layers. Furthermore, if any two of layers 1 to 3 are paper substrate laminates, the remaining layer is formed as a paper substrate layer. Furthermore, all of layers 1 to 3 may be paper substrate laminates. Although not shown, an adhesive layer 21 may be interposed between the layers of the paper substrate laminate (between the inner layer and the metal layer).

In this embodiment, the first to third layers (the innermost and middle layers) have a structure in which the paper substrate laminate formed into a strip-shaped sheet is spirally wound with the inner layer facing inward, or a structure in which the paper substrate formed into a strip-shaped sheet is spirally wound, and the fourth layer has a structure in which the paper substrate formed into a strip-shaped sheet is spirally wound. In this case, the first layer, which is the innermost layer, and the fourth layer, which is the outermost layer, are spirally wound with the peripheral edges of the strip-shaped sheets overlapping and in contact with each other. The overlap width at the contact points is preferably a maximum of 1 mm, more preferably 0.1 mm to 1 mm, and most preferably 0.2 mm to 0.8 mm. Limiting the overlap width to a maximum of 1 mm can prevent liquid leakage from the contact points (seams). Furthermore, even when pressure (load) is applied from the inside to the outside to the tip of the liquid containing member 11 due to press-fitting, the repulsive force caused by the overlapping contact points prevents tearing or peeling of the adhesive surface, resulting in a liquid containing member 11 with excellent reliability and durability. However, if the overlap width exceeds 1 mm, a step will form at the overlapping portion, which may lead to liquid leakage.

On the other hand, the second and third intermediate layers are wound spirally, for example, with the peripheral portions of the strip-shaped sheet in contact with each other so as not to overlap (see Figure 2(a)). This reduces the tube thickness. There are no particular limitations on the way the intermediate layers are wound. For example, at least one of the second and third layers may be wound spirally with the peripheral portions of the strip-shaped sheet in contact with each other so as to overlap. The overlap width at the contact points is the same as for the first and fourth layers. In the example of Figure 2(b), both the second and third layers are wound spirally with the peripheral portions of the strip-shaped sheet in contact with each other so as to overlap. By increasing the number of layers wound spirally with the peripheral portions of the strip-shaped sheet in contact with each other so as to overlap, the repulsive force is further strengthened, resulting in a liquid containing member 11 with even greater reliability and durability.

In addition, in this embodiment, the spacing of the seams (contact points) between adjacent layers is specified. For example, the spacing of the seams between adjacent layers (the seam between the first layer and the second layer, the seam between the second layer and the third layer, etc.) is preferably 1 mm or more and half the sheet width or less along the longitudinal direction of the liquid containing member 11, and more preferably 3 mm or more and half the sheet width or less.

In this embodiment, the intermediate layer has a two-layer structure (second and third layers) as an example, but this is not limited to this. The number of layers in the intermediate layer may be three or more, depending on the usage conditions of the writing instrument and the product specifications (materials, dimensions, etc.). If the intermediate layer has three or more layers, i.e., a three-layer structure, four-layer structure, etc., the outermost layer will be the fifth layer, sixth layer, etc. In this case, as with the layers other than the outermost layer (the innermost layer and intermediate layer), at least one of these layers will form a layer of the paper substrate laminate, as described above.

<Paper base material and paper base material laminate>
As the paper substrate (the paper substrate used in the first to fourth layers (including the inner layer of the paper substrate laminate)), various known materials can be used, such as fine paper, medium-quality paper, one-side glazed paper, kraft paper, one-side glazed kraft paper, bleached kraft paper, paperboard, white paperboard, liner, lightly coated paper, coated paper, art paper, cast-coated paper, glassine paper, parchment paper, and vulcanized fiber. The density of these paper substrates is preferably 0.8 g/cm ^or more. By using a paper substrate with a density of 0.8 g/cm or ^more , sufficient water resistance and oil resistance can be imparted. Furthermore, the paper substrate is more preferably glassine paper, parchment paper, or vulcanized fiber, and has a density of 0.8 g/cm or ^more .

Glassine paper is a high-density, highly transparent paper made by extensively beating virgin pulp to increase its specific surface area, and then treating the paper with a supercalender to densify it and strengthen the bonds between the cellulose fibers. In this embodiment, glassine paper with a basis weight of 20 to 50 g/ ^m2 is used. Using glassine paper as a paper substrate makes it easy to impart water resistance and oil resistance. Alternatively, glassine paper with a basis weight of 20 to 50 g/ ^m2 may be used as a base paper, with one or both sides coated with a coating liquid such as an aqueous polyvinyl alcohol solution. The thickness of the glassine paper is usually 20 to 50 μm, preferably 20 to 30 μm.

Parchment paper and vulcanized fiber are made by treating them with concentrated sulfuric acid or zinc chloride solution during the manufacturing process, which strengthens the direct bonds between the cellulose fibers, i.e., increases the density of the cellulose hydrogen bonds between the cellulose fibers. Therefore, using parchment paper and vulcanized fiber as a paper base material can effectively reduce the generation of paper dust.

The parchment paper used has a basis weight of, for example, 20 to 100 g/ ^m² , and preferably has enhanced oil resistance so that the oil absorption is 13 g/ ^m² or less when mineral oil is used instead of water in accordance with the water absorption test method for paper and paperboard (Cobb method). The thickness of the parchment paper is usually 20 to 100 µm, and preferably 20 to 60 µm.

Due to differences in reactivity during the manufacturing process, vulcanized fiber can be made thicker than parchment paper. Therefore, it is suitable for cases where thick cardboard is required as the paper substrate. The thickness of the vulcanized fiber is typically 0.08 to 1 mm, preferably 0.1 to 0.5 mm, taking into consideration the compressive strength of the paper tube portion after the liquid containing member 11 is manufactured and ease of handling during manufacturing. Furthermore, the density of vulcanized fiber is higher than that of general paper tube base paper, typically 0.8 to 1.4 g/cm ^3. In this embodiment, a density of 0.8 to 1.3 g/cm ³ is preferred, taking into consideration the strength of the paper tube portion and ease of availability.

Parchment paper and vulcanized fiber may also be subjected to a resin impregnation or glass coating process. This treatment further strengthens the bonds between the cellulose fibers, and when these papers are used as paper substrates, the generation of paper dust can be reduced.

The paper substrate laminate is a composite material in which a metal layer or a silica vapor deposition layer is laminated on the outer surface side of an inner layer formed as a paper substrate layer. The metal layer that constitutes this paper substrate laminate may be formed by bonding a metal foil such as aluminum foil to one side of the paper substrate using an adhesive containing polyolefin resin, or by depositing aluminum or an alloy of aluminum and zinc by electron beam deposition under vacuum.

<Adhesive>
Here, we will explain the adhesive containing polyolefin resin used in the adhesive layer 21. The adhesive containing polyolefin resin may be an adhesive made of one or more polyolefin resins, or may be an adhesive made by mixing this polyolefin resin with other resins.

Specific examples of polyolefin resins include polyethylene ionomers, polypropylene ionomers, polypropylene elastomers, polyethylene elastomers, high-density polyethylene, and low-density polyethylene, as well as modified polyolefin resins such as maleic anhydride-modified polypropylene. Of these, polypropylene ionomers and maleic anhydride-modified polypropylene are preferred.

Specific examples of other resins include acrylic acid copolymers, ethylene-vinyl alcohol copolymers (EVOH), ethylene-acrylic acid copolymers (EAA), ethylene-methacrylic acid copolymers (EMAA), epoxy resins, carbodiimide crosslinkers, ethylene-vinyl acetate copolymers, and polyvinyl alcohol.

When polyolefin resin is mixed with other resins, the proportion of polyolefin resin in the total adhesive is approximately 60 to 97% by weight, preferably 90 to 97% by weight. Furthermore, when polyolefin resin and other resins are combined, the proportion of polyolefin resin is approximately 68 to 98% by weight, preferably 93 to 98% by weight.

The polyolefin resin-containing adhesive of this embodiment is used in the form of a dispersion or emulsion type resin liquid, with a polyolefin resin or a mixture of polyolefin resin and other resins as the base polymer. Additives such as silane coupling agents may be added to this resin liquid as needed. Of these, dispersion type adhesives such as polypropylene ionomer and maleic anhydride-modified polypropylene are preferred due to their excellent adhesive properties and ease of handling.

The adhesive containing the polyolefin resin described above is applied to at least one of the first and second layers, the second and third layers, and the third and fourth layers of the liquid containing member 11. That is, an adhesive layer 21 may be provided between any one of the first and second layers, the second and third layers, or the third and fourth layers, or between any two of these layers, or between all of these layers. An adhesive layer 21 may also be provided between each layer constituting the paper substrate laminate (between the inner layer and the metal layer). Applying an adhesive containing a polyolefin resin with excellent adhesion to paper and ink resistance ensures close contact between the layers, effectively preventing ink leakage outside the liquid containing member 11. Here, ink resistance refers to the degree to which the adhesive resin component is prevented from leaching into ink. Insufficient ink resistance can result in a decrease in refill strength, an increase in volatile loss, and even poor appearance of the refill due to ink leakage. When using an adhesive containing polyolefin resin, the compatibility with ink is low, so the polyolefin resin does not dissolve into the ink, and these effects on ink resistance can be expected.

In addition, by applying an adhesive containing a polyolefin resin with the above-mentioned effects between each of the first through fourth layers and between each of the layers that make up the paper base laminate (between the inner layer and the metal layer), the strength of the liquid containing member 11 is increased, which can provide a certain level of effectiveness in preventing problems such as tearing of the liquid containing member 11 and peeling of the adhesive surface.

In this embodiment, at least one of the first and second layers, the second and third layers, and the third and fourth layers of the liquid containing member 11 can be bonded together with an adhesive containing polyolefin resin. For layers that do not use an adhesive containing polyolefin resin, other adhesives, such as vinyl acetate resin, acrylic resin, or polyvinyl alcohol, may be used in combination.

<Production method>
Next, a method for manufacturing the liquid containing member 11 will be described. In this embodiment, as an example, a case will be described in which the first layer (innermost layer) is formed of a paper substrate laminate, and the second to fourth layers are formed as paper substrate layers. As an example, for the paper substrate laminate, a metal layer is laminated on the outer surface side of the inner layer formed as a paper substrate layer. In this embodiment, the first and fourth layers are spirally wound around the strip-shaped sheets with their peripheral edges in contact with each other so as to overlap, and the second and third layers are spirally wound around the strip-shaped sheets with their peripheral edges in contact with each other so as not to overlap.

Based on the above premise, for example, when forming the innermost layer, first, a polyolefin resin-containing adhesive is applied in a mound near the center of the inner layer or metal layer that constitutes the paper substrate laminate. Next, the inner layer and the metal layer are pressed together, and the adhesive is spread over the entire bonding surface, bonding the two layers together so as not to leave any air bubbles in the bonded area and to eliminate any adhesive defects. After the inner layer and the metal layer are bonded together, they are pressed together and fixed under pressure until the adhesive hardens. This results in a paper substrate laminate configured as a composite material. The amount of polyolefin resin-containing adhesive applied to the inner layer or metal layer is 5 to 50 g/ ^m² , preferably 5 to 25 g/ ^m² .

The paper substrate laminate may be formed using a paper substrate and a metal layer (or a silica vapor deposition layer) of the same thickness, or may be formed by appropriately combining paper substrates and metal layers (or silica vapor deposition layers) of different thicknesses. In the paper substrate laminate, the ratio of the thickness of the paper substrate to the thickness of the metal layer (or silica vapor deposition layer) is preferably approximately 2/1 to 1200/1.

Next, the paper substrate laminate formed as the composite material is cut into widths of 4 to 20 mm using a bobbin slitter or similar, to obtain a paper substrate laminate formed into a strip-shaped sheet.

The resulting paper base laminate is then spirally wound around a mandrel (paper tube manufacturing machine) for processing the liquid containing member 11, with the inner layer facing inward. At this time, the paper base laminate that forms the first layer is spirally wound with the peripheral edges of the strip-shaped sheets overlapping and in contact with each other.

The first layer (innermost layer) is formed through the above process. To facilitate removal of the mandrel after the first through fourth layers (innermost layer) have been formed, it is preferable to pre-treat the surface of the mandrel with an appropriate lubricant, or to apply an appropriate amount of lubricant to the surface of the inner layer that will be wound around the mandrel.

The paper base laminate is preferably a strip-shaped sheet cut to a width of 4 to 20 mm, and more preferably a strip-shaped sheet cut to a width of 5 to 15 mm. By spirally winding such a wide paper base laminate, the required length of the liquid containing member 11 can be achieved without multiple windings. As a result, the number of contact points between the paper base laminates, i.e., the number of seams, can be reduced, and leakage of the liquid contained in the liquid containing member 11 can be suppressed.

Next, a paper substrate formed into a strip-shaped sheet is spirally wound around the outer surface of the first layer to form the second layer. The paper substrate forming the second layer is spirally wound with the peripheral edges of the strip-shaped sheet in contact with each other so as not to overlap. The second layer is preferably formed using a paper substrate with a width of 4 to 20 mm, and more preferably a paper substrate with a width of 6 to 15 mm. As with the paper substrate laminate described above, reducing the number of seams helps prevent leakage of liquid from the liquid containing member 11. The paper substrate forming the second layer can also be the same as the paper substrate forming the inner layer of the paper substrate laminate described above. Alternatively, a polyolefin resin-containing adhesive may be applied to the metal layer on the outer surface of the first layer, and the second layer may be bonded to this metal layer. The amount of polyolefin resin-containing adhesive used here is approximately the same as the amount applied to the inner layer or metal layer of the paper substrate laminate.

Next, a paper substrate formed into a strip-shaped sheet is spirally wound around the outer surface of the second layer to form the third layer. In this case, the paper substrate forming the third layer is spirally wound, similar to the second layer, with the peripheral edges of the strip-shaped sheet in contact with each other so as not to overlap. Similarly to the second layer, the third layer is preferably formed using a paper substrate with a width of 4 to 20 mm, and more preferably a paper substrate with a width of 6 to 15 mm. As above, reducing the number of seams helps prevent leakage of liquid from the liquid containing member 11. The paper substrate forming the third layer can be the same as the paper substrate forming the inner layer and second layer of the paper substrate laminate. Alternatively, an adhesive containing a polyolefin resin can be applied to the outer surface of the second layer, and the paper substrate for the third layer can be adhered to this adhesive-coated surface. The amount of adhesive containing a polyolefin resin used here is approximately the same as the amount applied to the inner layer or metal layer of the paper substrate laminate.

Finally, a paper substrate formed into a strip-shaped sheet is spirally wound around the outer surface of the third layer to form the fourth layer (outermost layer). The paper substrate forming the outermost layer is spirally wound with the peripheral edges of the strip-shaped sheet overlapping each other. As with the third layer, the outermost layer is preferably formed using a paper substrate with a width of 4 to 20 mm, and more preferably a paper substrate with a width of 6 to 15 mm. As above, reducing the number of seams helps prevent leakage of liquid from the liquid containing member 11. The paper substrate forming the outermost layer can be the same as the paper substrate forming the inner, second, and third layers of the paper substrate laminate. Alternatively, an adhesive containing a polyolefin resin can be applied to the outer surface of the third layer, and the paper substrate for the outermost layer can be adhered to this adhesive-coated surface. The amount of adhesive containing a polyolefin resin used here is approximately the same as the amount applied to the inner layer or metal layer of the paper substrate laminate.

After the first, second, third, and fourth layers are formed, the mandrel is removed, and the cylindrical molded body is cut to the specified length required for the liquid containing member 11. The desired liquid containing member 11 is obtained by drying for several hours at an appropriate temperature and humidity. Note that in this embodiment, for the sake of convenience, the second and third layers are spirally wound with their peripheral edges in contact and not overlapping, but this is not a limitation. Similar to the first and fourth layers, the second and third layers can also be spirally wound with their peripheral edges in contact and overlapping. Also, in this embodiment, the second and third layers are formed as paper substrate layers, but this is not a limitation. Similar to the first layer, they may be formed from a paper substrate laminate.

The outer diameter of the liquid containing member 11 manufactured as described above is typically 20 mm or less, preferably 15 mm or less, and more preferably 10 mm or less, with the lower limit of this outer diameter typically being 1 mm or more, and preferably 2 mm or more.

The tube thickness of the liquid containing member 11 is typically 0.07 to 0.6 mm, specifically 0.2 to 0.4 mm. By keeping the tube thickness of the liquid containing member 11 within this range, it is possible to contain a sufficient amount of liquid, while improving barrier properties and making it easier to prevent liquid leakage and deterioration.

Furthermore, it is preferable that the rate of change in the overall length of the liquid containing member 11 after filling with ink (i.e., the initial period) and after 300 m of writing is less than 0.7%. The change in overall length refers to the shortening of the overall length in the axial direction due to deformation, such as bending, of the liquid containing member 11 caused by creep stress constantly applied to the ink containing tube 11 during writing. Figure 3 is a diagram that schematically illustrates an example of the amount of change in overall length relative to the initial length, showing the state of a writing instrument refill before and after writing. The rate of change in overall length (%) can be expressed by the following formula (1):

Overall length change rate = (change amount/initial length) × 100 (%) ... (1)

If the overall length change rate is 0.7% or more, it may have an adverse effect on the writing feel, particularly before the ink runs out. Because the liquid containing member 11 manufactured with the configuration of this embodiment has excellent reliability and durability as described above, it is possible to achieve an overall length change rate of less than 0.7%.

Furthermore, when the refill 10 is used at an angle of 60°, i.e., when a load is applied to the refill 10 at an angle of 60°, it is preferable that the bending strength of the liquid containing member 11 be 0.5 N or greater. Figure 4 is a diagram showing how a load is applied to the refill 10 at an angle of 60°. If the bending strength of the liquid containing member 11 is less than 0.5 N, it may easily buckle when writing. The liquid containing member 11 manufactured with the configuration of this embodiment has excellent reliability and durability as described above, making it possible to achieve a bending strength of 0.5 N or greater.

It is also preferable that the difference between the outer diameter and inner diameter of the liquid containing member 11 be 0.3 mm or more.

In addition, in this embodiment, a laser or the like is used to remove the outer surface of the liquid containing member 11 in the refill 10 until the metal layer or silica vapor deposition layer is exposed. This allows for the visual difference between the outer surface of the liquid containing member 11 and the metal layer or silica vapor deposition layer to add (print) text information such as the product name or lot number. Figure 5 is a diagram showing an example of text information printed on the exposed metal layer or silica vapor deposition layer. In Figure 5, as an example, the text information "20210822" is printed on the surface of the metal layer or silica vapor deposition layer of the paper base laminate that forms the third layer.

<Effects>
As described above, the liquid containing member 11 of this embodiment is composed of a first layer, which is the innermost layer that comes into contact with the liquid, second and third layers, which are intermediate layers, and a fourth layer, which is the outermost layer. At least one of the first, second, and third layers is formed as a paper substrate laminate layer in which a metal layer or a silica vapor deposition layer is laminated on the outer surface side of the inner layer formed from a paper substrate, the other layers are formed as paper substrate layers, and the fourth layer is formed as a paper substrate layer. Furthermore, the paper substrate laminate layer has a structure in which a paper substrate laminate formed into a strip-shaped sheet is spirally wound with the inner layer facing inward, and the paper substrate layer has a structure in which a paper substrate formed into a strip-shaped sheet is spirally wound, and the first and fourth layers are spirally wound with the peripheral portions of the strip-shaped sheets in contact with each other so as to overlap. This makes it possible to obtain a liquid container 11 that is highly reliable and durable, and that does not easily tear or peel off from the adhesive surface due to the repulsive force caused by the overlapping of contact points, even when pressure (load) is applied from the inside to the outside to the tip of the liquid container 11 due to press-fitting.

Although there are no particular limitations on the refill 10 including the liquid containing member 11 of this embodiment, it is preferable to use the following inks:

<Ink>
A suitable ink to be contained in the liquid containing member 11 of this embodiment is an ink composition containing at least a black coloring component, and one or a mixture of two or more selected from salt forming dyes containing at least C.I. Acid Yellow 36, C.I. Acid Yellow 23, C.I. Acid Yellow 36 or C.I. Acid Yellow 23 as a constituent element, an amphoteric surfactant, and zinc ions, and a black coloring component, and at least C.I. Acid Yellow 36, C.I. Acid Yellow 23, C.I. Acid Yellow 36 or C.I. Acid Yellow 23 as a constituent element, and a mixture of two or more selected from the group consisting of C.I. Acid Yellow 36, C.I. Acid Yellow 23, C.I. Acid Yellow 23 as a constituent element ... The ink contains a black ink composition containing at least one or a mixture of two or more salt-forming dyes containing Acid Yellow 23 as a constituent element, and an amphoteric surfactant.

An acid dye binds to the positively charged portion of the amphoteric surfactant, and zinc ions react with the negatively charged portion, dissolving in the ink as a black colorant, creating highly black handwriting.

The amphoteric surfactant is used to bond with the acid dye in the ink composition at the positively charged portion and to undergo a bonding reaction with zinc ions at the negatively charged portion.

Examples of amphoteric surfactants include betaine-type amphoteric surfactants and imidazoline-type amphoteric surfactants. Specifically, betaine-type amphoteric surfactants such as NIKKOL AM 301 (lauryldimethylaminoacetic acid betaine, manufactured by Nikko Chemicals Co., Ltd.), NIKKOL AM 3130N (coconut oil fatty acid amidopropyl betaine, manufactured by Nikko Chemicals Co., Ltd.), NIKKOL AM 101 (2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, manufactured by Nikko Chemicals Co., Ltd.), AMOGEN SH (lauryl betaine, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), ADEKA AMFORT PB-30L (laurylamidopropylacetic acid betaine, manufactured by Adeka Corporation), and AMOGEN AB-35L (laurylaminoacetic acid betaine, manufactured by Adeka Corporation) can be used; and imidazoline-type amphoteric surfactants such as AMOGEN K (alkylamine carboxylic acid derivative, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) and AOL (lauryldimethylamino oxide, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) can be used. In particular, the betaine-type amphoteric surfactant NIKKOL AM 3130N (coconut oil fatty acid amidopropyl betaine, manufactured by Nikko Chemicals Co., Ltd.) is preferred because the acid dye bonds with this amphoteric surfactant and then undergoes a bonding reaction with zinc ions to produce a black color, thereby producing handwriting with a high degree of blackness. These amphoteric surfactants may be used alone or in combination of two or more. The amount of amphoteric surfactant blended is preferably 0.005% by weight or more and 10.0% by weight or less of the total amount of the ink composition.

The acid dye is not particularly limited as long as it contains at least C.I. Acid Yellow 36 and/or C.I. Acid Yellow 23. Furthermore, when a salt-forming dye formed from C.I. Acid Yellow 36 and/or C.I. Acid Yellow 23 and a basic dye is used as the black coloring component, the unreacted material from the salt-forming reaction may be used.

The zinc ions may be zinc ions ionized by blending a zinc-containing compound into the ink composition, or may be zinc ions eluted from a metal component that is made of zinc or a zinc-containing alloy and comes into contact with the ink composition.

Examples of zinc-containing compounds include zinc chloride, zinc oxide, zinc oxalate, zinc acetate, zinc borate, zinc formate, zinc lactate, zinc phosphate, zinc pyrophosphate, zinc salicylate, zinc stearate, zinc sulfate, and zinc sulfide. The amount of zinc-containing compounds is preferably 0.005% by weight or more and 10.0% by weight or less of the total amount of the ink composition.

An example of a metal component that comes into contact with the ink composition is the ball holder used in ballpoint pen tips. The material of the metal component is not particularly limited as long as it contains zinc. Specific examples include copper-zinc alloys such as red brass, brass, and copper for detonators; copper-zinc-lead alloys such as free-cutting brass and brass for nipples; copper-zinc-tin alloys such as naval brass and condenser brass; copper-zinc-nickel alloys such as nickel silver, cupronickel, nickel silver for springs, and nickel silver for forging; copper-zinc-nickel-lead alloys such as free-cutting nickel silver; copper-zinc-lead-manganese-tin alloys such as brass for musical instrument valves; copper-tin-phosphorus-zinc alloys such as phosphor bronze for springs; copper-zinc-aluminum-iron-manganese-nickel alloys such as high-strength brass; and aluminum-zinc alloys. Nickel silver is particularly preferred due to its excellent workability and beautiful appearance.

Black coloring components include conventionally known acid dyes, basic dyes, and salt-forming dyes. Salt-forming dyes made from an acid dye and a basic dye are particularly preferred.

Specific examples that can be used include a salt-forming dye made from C.I. Acid Yellow 36 and C.I. Basic Violet 3, a salt-forming dye made from C.I. Acid Yellow 23 and C.I. Basic Violet 3, and a salt-forming dye made from C.I. Acid Yellow 23 and C.I. Basic Violet 1.

The amount of black coloring component in the ink composition is preferably 10% by weight or more and 50% by weight or less, based on the total amount of the ink composition.

In addition, the ink composition of this embodiment may contain pigments, organic solvents, resins, etc. as appropriate.

Examples of pigments include carbon black, insoluble azo pigments, azo lake pigments, condensed azo pigments, diketopyrrolopyrrole pigments, phthalocyanine pigments, quinacridone pigments, isoindolinone pigments, isoindoline pigments, anthraquinone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, quinophthalone pigments, perinone, and organic pigments such as perylene pigments. These pigments may be used alone or in combination of two or more.

Organic solvents include ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, ethylene glycol dibutyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monohexyl ether, ethylene glycol mono-2-ethylhexyl ether, ethylene glycol monoallyl ether, diethylene glycol monophenyl ether, diethylene glycol monobenzyl ether, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol monoethyl ether, diethylene glycol Diethylene glycol diethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoisobutyl ether, diethylene glycol dibutyl ether, diethylene glycol monohexyl ether, diethylene glycol mono 2-ethylhexyl ether, triethylene glycol monomethyl ether, triethylene glycol dimethyl ether, triethylene glycol monobutyl ether, polyethylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol tert-butyl ether, propylene glycol monophenyl ether glycol ethers such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol dimethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monobutyl ether, 3-methyl-3-methoxy-1-butyl acetate, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, hexylene glycol, octylene glycol, glycerin, polyethylene glycol, 3-methyl-1,3-butanediol, 1,3-propanediol, 1,3-butanediol, 1,5 Examples of suitable organic solvents include glycols such as 1-pentanediol, benzyl alcohol, β-phenylethyl alcohol, α-methylbenzyl alcohol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 3-methoxy-1-butanol, 3-methyl-3-methoxy-1-butanol, 3-methyl-3-methoxypentanol, lauryl alcohol, tridecyl alcohol, isodecyl alcohol, and isotridecyl alcohol; ethers such as methyl isopropyl ether, ethyl ether, ethyl propyl ether, ethyl butyl ether, isopropyl ether, butyl ether, hexyl ether, and 2-ethylhexyl ether; and esters such as 2-ethylhexyl acetate, isobutyl isobutyrate, ethyl lactate, and butyl lactate. These may be used alone or in combination. The amount of these organic solvents is preferably 10% by weight or more and 90% by weight or less of the total ink weight.

Resins are added to disperse pigments, impart threadability, prevent show-through, adjust viscosity, and promote dye dissolution. Examples include ester gum, xylene resin, alkyd resin, polyvinylpyrrolidone, acrylic ester resin, melamine resin, cellulose resin, condensation resins of ketones such as cyclohexanone, acetophenone, and urea with formaldehyde, cyclohexanone condensation resins and hydrogenated resins thereof, maleic acid resin, copolymers of styrene and maleic acid ester, copolymers of styrene and acrylic acid or its ester, polyamides which are condensates of polymerized fatty acids and polyamines, epoxy resin, polyvinyl alkyl ether, coumarone-indene resin, polyterpene, rosin resins and their hydrogenated derivatives, rosin-modified maleic acid resins, and rosin-modified acrylic acid resins. Examples of suitable resins include phenolic resins, vinylpyrrolidone-vinyl acetate copolymers, polymethacrylates, polyoxyethylene, polyvinyl butyral resins, polyvinyl alcohol resins, polyvinyl acetal resins, copolymers of vinyl acetate and polyvinylpyrrolidone, acrylic resin salts, copolymers of acrylic acid and alkyl methacrylates or their salts, cellulose derivatives such as hydroxypropyl cellulose, hydroxyethyl cellulose, ethylhydroxyethyl cellulose, and ethyl cellulose, polysaccharides such as hydroxypropylated guar gum, methyl cellulose, ethyl cellulose, polyvinyl acetamide, polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl methyl ether, polyacrylic acid, and carboxyvinyl polymers, and benzylidene sorbitol. Polyvinyl butyral resins are particularly preferred because they exhibit minimal viscosity change over time and provide excellent pigment dispersion stability and fixation. These resins may be used alone or in combination. The amount of these resins is preferably 0.05% by weight or more and 30.0% by weight or less of the total weight of the ink composition.

The ink viscosity at 25° C. and a shear rate of 100 s ⁻¹ is preferably 10 mPa·s or more and 5000 mPa·s or less, and more preferably 200 mPa·s or more and 1000 mPa·s or less.

The pH is preferably 3.0 or higher and 10.0 or lower. A pH of 6.0 or higher and 8.0 or lower is particularly preferred.

The black oil-based ink composition of this embodiment can be produced by the following method.

The black coloring component and/or acid dye and amphoteric surfactant are thoroughly mixed in a stirrer such as a homomixer, and the acid dye is bonded to the positively charged portion of the amphoteric surfactant. After that, pigments, organic solvents, resins, etc. are added as needed and mixed in the stirrer. Next, a zinc-containing compound is added and thoroughly mixed in the stirrer, and zinc ions are bonded to the negatively charged portion of the amphoteric surfactant.

If zinc or a zinc-containing alloy is used for the metal component that comes into contact with the ink composition, the black coloring component and/or acid dye and amphoteric surfactant are thoroughly mixed in a stirrer such as a homomixer, and the acid dye is bound to the positively charged portion of the amphoteric surfactant. After that, pigments, organic solvents, resins, etc. are added as needed and mixed in the stirrer.

The agitator can also be replaced with a dispersing machine such as a homogenizer for mixing and dispersion, or the resulting black oil-based ink can be filtered or centrifuged to remove coarse particles and insoluble components. It is also possible to heat the ink using an electric heater or band heater, or cool it using a cooling machine. It is preferable to keep the ink temperature during production between 5°C and 95°C.

In the refill 10 of this embodiment, the black oil-based ink composition is filled into a liquid containing member 11, which has a ballpoint pen tip 13 attached to its tip via a joint 12. Then, by placing this refill 10 in a barrel, a ballpoint pen, which is the writing instrument of this embodiment, is obtained.

<Writing instrument configuration>
Figure 6 shows an example of the configuration of a ballpoint pen, which is a writing instrument in which a writing instrument refill is housed in a barrel, where Figure 6(a) shows a front view of the appearance of the writing instrument in a writing state, Figure 6(b) shows a cross-sectional view of the writing instrument in a writing state, Figure 6(c) shows a front view of the appearance of the writing instrument in a stored state, and Figure 6(d) shows a cross-sectional view of the writing instrument in a stored state.

In Figure 6, the writing instrument 30 comprises a barrel 31, which is a cylindrical member molded into a cylindrical shape; a cylindrical operating member 32 provided at the front of the barrel 31; and the refill 10 described above, with the operating member 32 moving in the front-to-rear direction relative to the barrel 31. At this time, the state in which the tip of the ballpoint pen tip 13 protrudes from the operating member 32 is referred to as the writing state, and the state in which the tip of the ballpoint pen tip 13 is retracted into the operating member 32 is referred to as the storage state.

The barrel 31 has a cylindrical barrel body 31a with a closed rear end, and a columnar refill holder 31b that extends forward from the inner surface of the closed rear end of the barrel body 31a, beyond the barrel body itself. A spiral ridge-like convex portion protruding radially inward is formed on the inner peripheral surface of the rear portion of the barrel body 31a, and this convex portion as a whole forms a female thread portion 31c.

The refill holding portion 31b also has an insertion hole for inserting the refill 10, and at the back of the insertion hole is a fitting portion 31d that fits with the rear end of the refill 10. The inner diameter of the fitting portion 31d is approximately the same as or slightly smaller than the outer diameter of the rear end of the refill 10. Therefore, when the refill 10 is inserted into the insertion hole of the refill holding portion 31b, it is fixed and held in place by the fitting between the rear end of the refill 10 and the fitting portion 31d of the refill holding portion 31b, preventing it from easily coming out.

Note that the configuration of the writing instrument 30 in this embodiment is merely an example and is not limited to the above. For example, any structure and shape is acceptable as long as writing is possible with the refill 10 stored inside.

<Materials of barrel and operating member>
The barrel and the operating member contain biomass-derived polyolefin as an environmentally friendly material. Biomass-derived polyolefin uses biomass-derived ethylene as a raw material. Biomass-derived ethylene can be produced using biomass-derived ethanol as a raw material. In particular, it is preferable to use biomass-derived fermented ethanol obtained from plant raw materials. The plant raw material is not particularly limited, and conventionally known plants can be used. Examples include corn, sugarcane, beet, and manioc.

Biomass-derived polyolefins are produced by polymerizing monomers containing biomass-derived ethylene. When biomass-derived ethylene is used as the raw material monomer, the polymerized polyolefin is biomass-derived. Note that the raw material monomer for polyolefins does not have to contain 100% biomass-derived ethylene by mass.

The monomers used as raw materials for biomass-derived polyolefins may further contain at least one selected from fossil fuel-derived ethylene and fossil fuel-derived α-olefins, or may further contain biomass-derived α-olefins.

The number of carbon atoms in the α-olefin is not particularly limited. The number of carbon atoms in the α-olefin is usually an integer from 3 to 20. The α-olefin is preferably butylene, hexene, or octene.

Because there are no differences in molecular weight, mechanical properties, thermal properties, or other physical properties between biomass-derived polyolefins and fossil fuel-derived polyolefins, the biomass plastic content defined in ASTM D6866 is commonly used to distinguish between them. Radioactive carbon-14C exists in the atmosphere at a ratio of 1 in 1012 particles, and this ratio is the same for atmospheric carbon dioxide, so it remains the same even in plants that fix this carbon dioxide through photosynthesis. For this reason, the carbon in biomass-derived polyolefins contains radioactive carbon-14C. In contrast, the carbon in petroleum-derived resins contains almost no radioactive carbon-14C. Therefore, by measuring the concentration of radioactive carbon-14C in the resin using an accelerator mass spectrometer, the proportion of plant-derived resin in the resin, i.e., the biomass plastic content, can be determined.

The biomass plastic content of biomass-derived polyolefins is not particularly limited. From the perspective of being carbon neutral and environmentally friendly, the biomass plastic content of biomass-derived polyolefins is preferably at least 80%. The upper limit is not particularly limited, but is usually less than 99% due to the possibility of other agents being mixed in during molding. Therefore, the biomass plastic content of biomass-derived polyolefins is preferably at least 80% but less than 99%.

Suitable examples of biomass-derived polyolefins include polyethylene-based resins and polypropylene-based resins. Polyethylene-based resins are preferred because silanol crosslinking can improve the recovery rate. Examples of polyethylene-based resins include high-density polyethylene (HDPE) with a density of 0.941 g/cm or ^more , ^{linear low} -density polyethylene (LLDPE) with a density of 0.910 g/cm ^or more but less than 0.94 g/cm, and low-density polyethylene (LDPE) with a density of 0.910 g/cm ^or more but less than 0.940 g/cm. The melt flow rate (MFR) of the polyolefin is not particularly limited. From the standpoint of moldability, the MFR (JIS K6922-1:1997 Appendix (190°C, 21.18 N load)) is preferably 1 g to 30 g/10 min, more preferably 1 g to 25 g/10 min, and even more preferably 1 g to 20 g/10 min.

Examples of biomass-derived polyolefins that can be used include Braskem products such as "SHA7260" (HDPE), "SBC818" (LDPE), and "SLL118/21" (LLDPE).

Example 1
<Manufacturing of Liquid Container Member>
In Example 1, the first layer (innermost layer) was formed from a paper substrate laminate, and the second to fourth layers were formed as paper substrate layers. In Example 1, as shown in Figure 2(a), the first and fourth layers were spirally wound with the peripheral portions of the strip sheets in contact with each other so as to overlap, and the second and third layers were spirally wound with the peripheral portions in contact with each other so as not to overlap.

Specifically, for the first layer (innermost layer), 25 μm thick glassine paper (basis weight 25 g/m ² , density 1.0 g/cm ³ ) and 6.5 μm thick aluminum foil were laminated together using a polyolefin resin-containing adhesive, Chemipearl S500, manufactured by Mitsui Chemicals, Inc. The laminate, with a total thickness of 38 μm including the 6.5 μm thick adhesive layer, was then cut into 13 mm wide strips using a bobbin slitter.

Then, 12 g/ ^m2 of the adhesive containing the polyolefin resin was applied to the aluminum foil side (outer layer) of the strip-shaped adhesive sheet using a roll applicator, and the sheet was spirally wrapped around the outer peripheral surface of a mandrel of a paper tube manufacturing machine (Langston) with the glassine paper facing inward. The adhesive sheet was spirally wrapped around the outer peripheral surface of the mandrel with the edges overlapping each other. The overlap width at the contact points was 0.5 mm.

Next, for the second layer, a 66 μm thick coated paper (basis weight 85 g/ ^m2 ) cut to a width of 13 mm using a bobbin slitter was spirally wound around the aluminum foil, which was the outer layer of the adhesive paper. The coated paper was wound spirally so that its peripheral edges were in contact with each other and butted against each other without overlapping. The seams of the first and second layers were spaced 3 mm apart in the longitudinal direction.

Next, for the third layer, a 66 μm thick coated paper (basis weight 85 g/ ^m2 ) cut to a width of 13 mm using a bobbin slitter was spirally wound around the paper substrate of the second layer. The coated paper was wound spirally so that its peripheral edges were in contact and butted together without overlapping. The seams of the second layer and the third layer were spaced 3 mm apart in the longitudinal direction.

Next, for the fourth layer (outermost layer), a 66 μm thick coated paper (basis weight 85 g/ ^m2 ) cut to a width of 13 mm using a bobbin slitter was spirally wound around the paper substrate of the third layer. The coated paper was spirally wound with its peripheral edges overlapping and in contact with each other. The overlap width at the contact points was 0.5 mm. The seams of the third and fourth layers were spaced 3 mm apart in the longitudinal direction.

After the first, second, third, and fourth layers were formed, the mandrel was removed and the cylindrical spiral tube was cut to a length of 89.3 mm. This was then dried for several hours at moderate temperature and humidity to obtain a liquid containing member (ink containing tube) of Example 1 with an inner diameter of 3.8 mm.

<Evaluation of Liquid Container Member>
The tip of the obtained liquid containing member of Example 1 was press-fitted into the joint, and the liquid containing member was checked for tearing or peeling of the adhesive surface. As a result, the liquid containing member of Example 1 was evaluated as good (A) without tearing or peeling of the adhesive surface (see Table 1).

Furthermore, the reduction in the total length of Example 1 after writing for 300 m was evaluated. The reduction in the total length of Example 1 after writing for 300 m was evaluated as follows:
・Writing load: 200g
・Speed: 4.5m/min
・Writing angle: 60°
The test was conducted under the conditions of (1), with the rest being in accordance with JIS S6039 (oil-based ballpoint pens and refills). The reduction in overall length is the rate of change in overall length, calculated by the above formula (1), for the overall length of the liquid containing member excluding the joint and ballpoint pen tip. As a result, the rate of change in overall length for the liquid containing member of Example 1 was 0.3% (less than 0.7%), and the evaluation was good (see Table 1).

In addition, in a refill state in which the liquid containing member of Example 1 is attached, the liquid containing member is gripped at a position 10 mm forward from the rear end thereof,
・Descent speed 10mm/min
- 60° inclination (see Figure 4)
The load until the liquid containing member buckled (bended) was measured under the conditions above. As a result, the bending strength of the liquid containing member of Example 1 was 1.3 N (0.5 N or more), and the evaluation was good (see Table 1).

Example 2
<Manufacturing of Liquid Container Member>
In Example 2, the first layer (innermost layer) was formed from a paper substrate laminate, and the second to fourth layers were formed as paper substrate layers, as in Example 1. In Example 2, as shown in Figure 2(b), all layers (first to fourth layers) were spirally wound with the peripheral portions of the strip-shaped sheets overlapping and in contact with each other.

Specifically, first, for the first layer (innermost layer), a paper substrate laminate layer was formed using the same procedure as in Example 1 described above. Next, for the second layer, a 66 μm thick coated paper (basis weight 85 g/ ^m2 ) cut to a width of 13 mm using a bobbin slitter was spirally wound around the aluminum foil, which was the outer layer of the adhesive paper. At this time, the coated paper was spirally wound with its peripheral edges overlapping and in contact with each other. The overlap width at the contact points was 0.5 mm. The winding was performed so that the seams of the first layer and the second layer were 3 mm apart along the longitudinal direction.

Next, for the third layer, a 66 μm thick coated paper (basis weight 85 g/ ^m2 ) cut to a width of 13 mm using a bobbin slitter was spirally wound around the paper substrate of the second layer. The coated paper was spirally wound with its peripheral edges overlapping and in contact with each other. The overlap width at the contact points was 0.5 mm. The seams of the second and third layers were spaced 3 mm apart in the longitudinal direction.

Next, for the fourth layer (outermost layer), a paper substrate layer was formed using the same procedure as in Example 1 described above.

After the first, second, third, and fourth layers were formed, the mandrel was removed and the cylindrical spiral tube was cut to a length of 89.3 mm. This was then dried for several hours at moderate temperature and humidity to obtain a liquid containing member (ink containing tube) of Example 2 with an inner diameter of 3.8 mm.

<Evaluation of Liquid Container Member>
The tip of the obtained liquid containing member of Example 2 was press-fitted into the joint, and the liquid containing member was checked for tearing or peeling of the adhesive surface. As a result, the liquid containing member of Example 2 was evaluated as good (A) without tearing or peeling of the adhesive surface (see Table 1).

Furthermore, for Example 2, the reduction in overall length after 300 m of writing was evaluated. The evaluation of the reduction in overall length after 300 m of writing was carried out under the same conditions as for Example 1. As a result, the overall length change rate for the liquid containing member of Example 2 was 0.3% (less than 0.7%), and the evaluation was good (see Table 1).

In addition, with the refilled container equipped with the liquid containing member of Example 2, the load required to cause the liquid containing member to buckle (bend) was measured under the same conditions as in Example 1. As a result, the bending strength of the liquid containing member of Example 2 was 1.5 N (over 0.5 N), and the evaluation was good (see Table 1).

<Comparative Example 1>
<Manufacturing of Liquid Container Member>
7A and 7B are diagrams showing the layer configurations of the liquid containing members in Comparative Examples 1 to 3. In Comparative Example 1, as in Example 1, the first layer (innermost layer) was formed from a paper substrate laminate, and the second to fourth layers were formed as paper substrate layers. In Comparative Example 1, as shown in FIG. 7A, all layers (first to fourth layers) were spirally wound with the peripheral portions of the strip-shaped sheets in contact with each other so as not to overlap.

Specifically, for the first layer (innermost layer), 25 μm thick glassine paper (basis weight 25 g/m ² , density 1.0 g/cm ³ ) and 6.5 μm thick aluminum foil were laminated together using a polyolefin resin-containing adhesive, Chemipearl S500, manufactured by Mitsui Chemicals, Inc. The laminate, with a total thickness of 38 μm including the 6.5 μm thick adhesive layer, was then cut into 13 mm wide strips using a bobbin slitter.

Then, 12 g/ ^m2 of the adhesive containing the polyolefin resin was applied to the aluminum foil side (outer layer) of the strip-shaped adhesive paper using a roll applicator, and the adhesive was spirally wrapped around the outer periphery of the mandrel of a paper tube manufacturing machine (Langston) with the glassine paper facing inward. At this time, the adhesive paper was spirally wrapped so that the peripheral edges were in contact with each other and not overlapping, but were butting against each other.

Next, for the second layer, a 66 μm thick coated paper (basis weight 85 g/ ^m2 ) cut to a width of 13 mm using a bobbin slitter was spirally wound around the aluminum foil, which was the outer layer of the adhesive paper. The coated paper was wound spirally so that its peripheral edges were in contact with each other and butted against each other without overlapping. The seams of the first and second layers were spaced 3 mm apart in the longitudinal direction.

Next, for the third layer, a 66 μm thick coated paper (basis weight 85 g/ ^m2 ) cut to a width of 13 mm using a bobbin slitter was spirally wound around the paper substrate of the second layer. The coated paper was wound spirally so that its peripheral edges were in contact and butted together without overlapping. The seams of the second layer and the third layer were spaced 3 mm apart in the longitudinal direction.

Next, for the fourth layer (outermost layer), a 66 μm thick coated paper (basis weight 85 g/ ^m2 ) cut to a width of 13 mm using a bobbin slitter was spirally wound around the paper substrate of the third layer. The coated paper was wound spirally so that its peripheral edges were in contact with each other and butted against each other without overlapping. The seams of the third and fourth layers were spaced 3 mm apart in the longitudinal direction.

After the first, second, third, and fourth layers were formed, the mandrel was removed and the cylindrical spiral tube was cut to a length of 89.3 mm. This was then dried for several hours at moderate temperature and humidity to obtain a liquid containing member (ink containing tube) of Comparative Example 1 with an inner diameter of 3.8 mm.

<Evaluation of Liquid Container Member>
The tip of the obtained liquid containing member of Comparative Example 1 was press-fitted into the joint, and the liquid containing member was checked for tearing and peeling of the adhesive surface. As a result, the liquid containing member of Comparative Example 1 was found to have both tearing and peeling of the adhesive surface, and was rated as poor (B) (see Table 1).

Furthermore, for Comparative Example 1, the reduction in overall length after 300 m of writing was evaluated. The evaluation of the reduction in overall length after 300 m of writing was carried out under the same conditions as in Example 1. As a result, the overall length change rate for the liquid containing member of Comparative Example 1 was 2.8% (over 0.7%), and the evaluation was poor (see Table 1).

In addition, with the refill equipped with the liquid containing member of Comparative Example 1, the load required to cause the liquid containing member to buckle (bend) was measured under the same conditions as in Example 1. As a result, the bending strength of the liquid containing member of Comparative Example 1 was 0.49 N (less than 0.5 N), and the evaluation was poor (see Table 1).

<Comparative Example 2>
<Manufacturing of Liquid Container Member>
In Comparative Example 2, the first layer (innermost layer) was formed from a paper substrate laminate, and the second to fourth layers were formed as paper substrate layers, as in Example 1. In Comparative Example 2, as shown in Fig. 7(b), the first to third layers were spirally wound with the peripheral portions of the strip-shaped sheets in contact with each other so as not to overlap, and the fourth layer was spirally wound with the peripheral portions in contact with each other so as to overlap.

Specifically, first, for the first layer (innermost layer), a paper substrate laminate layer was formed using the same procedure as in Comparative Example 1 described above. Next, for the second and third layers, paper substrate layers were formed using the same procedure as in Comparative Example 1 described above. Then, for the fourth layer (outermost layer), a paper substrate layer was formed using the same procedure as in Example 1 described above.

After the first, second, third, and fourth layers were formed, the mandrel was removed and the cylindrical spiral tube was cut to a length of 89.3 mm. This was then dried for several hours at moderate temperature and humidity to obtain a liquid containing member (ink containing tube) of Comparative Example 2 with an inner diameter of 3.8 mm.

<Evaluation of Liquid Container Member>
The tip of the obtained liquid containing member of Comparative Example 2 was press-fitted into the joint, and the liquid containing member was checked for tearing and peeling of the adhesive surface. As a result, the liquid containing member of Comparative Example 2 was found to have both tearing and peeling of the adhesive surface, and was rated as poor (B) (see Table 1).

Furthermore, for Comparative Example 2, the reduction in overall length after 300 m of writing was evaluated. The evaluation of the reduction in overall length after 300 m of writing was carried out under the same conditions as in Example 1. As a result, the overall length change rate for the liquid containing member of Comparative Example 2 was 0.6% (less than 0.7%), and the evaluation was good (see Table 1).

In addition, with the refill equipped with the liquid containing member of Comparative Example 2, the load required to cause the liquid containing member to buckle (bend) was measured under the same conditions as in Example 1. As a result, the bending strength of the liquid containing member of Comparative Example 2 was 0.85 N (over 0.5 N), and the evaluation was good (see Table 1).

<Comparative Example 3>
<Manufacturing of Liquid Container Member>
In Comparative Example 3, the first layer (innermost layer) was formed from a paper substrate laminate, and the second to fourth layers were formed as paper substrate layers, as in Example 1. In Comparative Example 3, as shown in Fig. 7(c), the peripheral portions of the strip-shaped sheet for the first layer were in contact with each other so as to overlap, and the peripheral portions of the second to fourth layers were in contact with each other so as not to overlap, and were spirally wound.

Specifically, first, for the first layer (innermost layer), a paper substrate laminate layer was formed using the same procedure as in Example 1 described above. Next, for the second to fourth layers, paper substrate layers were formed using the same procedure as in Comparative Example 1 described above.

After the first, second, third, and fourth layers were formed, the mandrel was removed and the cylindrical spiral tube was cut to a length of 89.3 mm. This was then dried for several hours at moderate temperature and humidity to obtain a liquid containing member (ink containing tube) of Comparative Example 3 with an inner diameter of 3.8 mm.

<Evaluation of Liquid Container Member>
The tip of the obtained liquid containing member of Comparative Example 3 was press-fitted into the joint, and the liquid containing member was checked for tearing and peeling of the adhesive surface. As a result, the liquid containing member of Comparative Example 3 did not tear and was rated as good (A), but peeling of the adhesive surface occurred and was rated as poor (B) (see Table 1).

Furthermore, for Comparative Example 3, the reduction in overall length after 300 m of writing was evaluated. The evaluation of the reduction in overall length after 300 m of writing was carried out under the same conditions as in Example 1. As a result, the overall length change rate for the liquid containing member of Comparative Example 3 was 0.5% (less than 0.7%), and the evaluation was good (see Table 1).

In addition, with the refill equipped with the liquid containing member of Comparative Example 3, the load required to cause the liquid containing member to buckle (bend) was measured under the same conditions as in Example 1. As a result, the bending strength of the liquid containing member of Comparative Example 3 was 1.1 N (over 0.5 N), and the evaluation was good (see Table 1).

<Summary>
Table 1 summarizes the evaluation results of Example 1, Example 2, Comparative Example 1, Comparative Example 2, and Comparative Example 3. In Table 1, "OW" means overlap (the peripheral edges of the strip sheets are in contact with each other so as to overlap), "butt" means no overlap, "A" means a good evaluation, and "B" means a poor evaluation.

10 Refill 11 Liquid storage member for writing instrument (liquid storage member)
12 Joint 13 Ballpoint pen tip 13a Spring 13b Writing ball 13c Holder 13c ₁ Cylindrical portion 13c ₂ Tapered portion 13c ₃ Ball house 13c ₄ Back hole 13c ₅ Ink hole 21 Adhesive layer 30 Writing implement 31 Shaft tube 31a Shaft tube main body 31b Refill holding portion 31c Female thread portion 31d Fitting portion 32 Operation member

Claims (12)

The innermost layer is in contact with the liquid, the intermediate layer is made up of at least two layers, and the outermost layer is composed of the innermost layer.
The layers other than the outermost layer are formed as a paper substrate laminate layer in which a metal layer or a silica vapor deposition layer is laminated on the outer surface side of an inner layer formed from a paper substrate, or as a paper substrate layer, and the sheet includes at least one paper substrate laminate layer and at least one paper substrate layer ,
Furthermore, the outermost layer is formed as a paper base layer,
The layer of the paper base laminate has a structure in which a paper base laminate formed into a strip-shaped sheet is spirally wound with the inner layer facing inward, and the layer of the paper base has a structure in which a paper base formed into a strip-shaped sheet is spirally wound,
The innermost layer and the outermost layer are wound in a spiral shape with the peripheral edges of the belt-shaped sheets overlapping and in contact with each other.
A liquid containing member for a writing implement. The intermediate layer has a two-layer structure,
With regard to the innermost layer and the intermediate layer, which are layers other than the outermost layer, at least one layer of the three layers, including the innermost layer and the intermediate layer, is formed as a layer of the paper base laminate.
2. The liquid containing member for a writing implement according to claim 1. an adhesive layer, which is a layer of an adhesive containing a polyolefin resin, is provided between at least one of the layers from the innermost layer to the outermost layer;
3. The liquid containing member for a writing instrument according to claim 1 or 2. The layers forming the intermediate layer are wound spirally around the belt-shaped sheet such that the peripheral edges of the sheets are in contact with each other without overlapping.
4. The liquid containing member for a writing implement according to claim 1, 2 or 3. At least one of the layers forming the intermediate layer is spirally wound around the belt-shaped sheet with peripheral edge portions thereof overlapping and in contact with each other.
4. The liquid containing member for a writing implement according to claim 1, 2 or 3. The paper base laminate has the inner layer and the metal layer bonded together with an adhesive containing a polyolefin resin.
6. The liquid containing member for a writing instrument according to claim 1, wherein the liquid containing member is a liquid containing member for a writing instrument. The paper base laminate and the paper base are formed into a strip-shaped sheet having a width of 4 to 20 mm.
7. The liquid containing member for a writing implement according to claim 1, wherein the liquid containing member is a liquid containing member for a writing implement. The total length change rate after 300m of writing is less than 0.7%.
8. The liquid containing member for a writing implement according to claim 1, wherein the liquid containing member is a liquid containing member for a writing implement. The bending strength is 0.5N or more when loaded at an angle of 60°.
9. The liquid containing member for a writing implement according to claim 1, wherein the liquid containing member is a liquid containing member for a writing implement. A liquid containing member for a writing instrument according to any one of claims 1 to 9;
ink for a writing instrument contained inside the liquid containing member for a writing instrument;
A writing member;
Equipped with
A refill for a writing instrument. removing the outer surface of the liquid containing member for a writing instrument until the metal layer or the silica vapor deposition layer forming the paper base laminate layer is exposed, thereby making it possible to display information on the metal layer or the silica vapor deposition layer;
11. The writing instrument refill according to claim 10. The writing instrument refill according to claim 10 or 11 is housed in a barrel,
The barrel contains a biomass-derived polyolefin.
A writing instrument characterized by: