JP4744829B2 - Writing instrument - Google Patents

Description

  The present invention relates to a writing instrument including a sign pen, a marker, a whiteboard marker, a ballpoint pen, a brush pen, a correction fluid pen, a brush pen, an applicator, and the like. It is related with the writing instrument which gave the appropriate fitting force to the fitting part at least.

  Generally, when the sealing performance of the cap is increased, the fitting force between the cap and the writing instrument main body shaft increases, and thus there are many problems that the cap of the pen body cannot be easily removed.

In order to solve this problem, conventionally, a liquid lubricant has been applied to adjust the fitting force between the cap and the writing instrument body shaft. Also known is a writing instrument cap characterized in that a coating layer of an elastic synthetic resin of urethane type, epoxy type, ethylene-vinyl acetate type or butyral type is provided at least on the inner peripheral surface to be fitted to the writing tool shaft body. (For example, refer to Patent Document 1).
However, in the case where the above-described lubricant is applied or the one provided with a coating layer of an elastic synthetic resin, there is a problem that a sufficient fitting force adjustment effect cannot be obtained unless a large amount is applied. There is a problem that may adhere to other than the fitting portion.

In order to solve these problems, the present applicant applied a highly polymerized dimethylpolysiloxane having a viscosity of 300,000 cps to 10 million cps at 20 ° C. to the inner surface of the cap, and the cap and cap of the writing instrument characterized in that (See, for example, Patent Document 2).
This writing instrument cap gives an unprecedented excellent mating force, but this mating force is temporary and the adhesion between the resin effect film and the shaft material is insufficient, so it is mating While repeating the above, problems such as peeling of the cured film occur.
Japanese Utility Model Publication No. 55-83381 (Scope of claims for utility model registration) JP-A-8-300879 (Claims, Examples, etc.)

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art and the current state of the art, and an object of the present invention is to provide a writing instrument that has a stable fitting force adjustment effect even when repeated fitting is performed. To do.

  As a result of intensive studies to solve the above-described conventional problems, the present inventors have formed a cured film having specific physical properties at least at the fitting portion between the front shaft and the shaft tube of the cap and the writing instrument, The inventors have found that a writing instrument for the above purpose can be obtained, and have completed the present invention.

That is, the present invention resides in the following (1) to (7).
(1) A writing instrument, wherein a silicone-cured polymer film is formed at least in a fitting portion between a tip shaft and a shaft tube of a cap and a writing instrument.
(2) The writing instrument according to the above (1), wherein the silicone cured polymer film is formed by applying a silicone varnish and then drying.
(3) The writing instrument according to the above (2), wherein the curing mechanism of the silicone varnish is any one of a condensation type, an addition type, and a UV type.
(4) The writing instrument according to (2) or (3) above, wherein a silicone varnish containing 1 to 10% by weight of silica fine particles is applied.
(5) The silicone-cured polymer film is formed in any one of the above (1) to (4), which is formed after the activation treatment is performed on at least the fitting portion between the front shaft and the shaft tube of the cap and the writing instrument. Writing instrument as described.
(6) The silicone cured polymer film is formed in any one of the above (1) to (4), which is formed after the adhesive layer treatment is performed on at least a fitting portion between the front shaft and the shaft tube of the cap and the writing instrument. Writing instrument as described.
(7) The writing instrument according to any one of (1) to (6), wherein the silicone cured polymer film has a thickness of 0.05 to 200 μm.
The “writing instrument” defined in the present invention includes writing instruments such as a sign pen, a marker, a whiteboard marker, a ballpoint pen, a brush pen, a correction liquid pen, and an applicator such as a liquid applicator and a cosmetic liquid applicator. It is a waste.

According to the present invention, the cured silicone polymer film that adjusts the fitting force is not peeled off even when the tip shaft and cap member of the writing instrument and the tip shaft and the shaft tube are repeatedly fitted, and the fitting force adjustment effect that is stable for a long time can be obtained. A writing instrument is provided.

Hereinafter, embodiments of the present invention will be described in detail.
The writing instrument of the present invention is characterized in that a silicone-cured polymer film is formed on at least the fitting part between the cap and the front shaft and the barrel of the writing instrument, and a sign pen, a marker, a marker for whiteboard, In addition to writing instruments such as ballpoint pens, brush pens, correction liquid pens, etc., the present invention can be applied to applicators such as liquid applicators and cosmetic liquid applicators.

1-4 is a writing instrument which shows 1st Embodiment of this invention.
FIG. 1 is a partial longitudinal sectional view showing a writing instrument according to a first embodiment of the present invention, and FIG. 2 is an operation state in which a tip shaft of the writing instrument is fitted to a shaft cylinder, and an operation in which a cap member is fitted to the tip axis. FIG. 3 is an enlarged partial vertical sectional view showing a fitting portion for forming a silicone-cured polymer film on a tip shaft that becomes a fitting portion between the cap and the shaft tube, and FIG. It is a front view which shows the state which removed.
As shown in FIGS. 1 to 3, the writing instrument A according to the first embodiment includes a shaft cylinder 12 including a front shaft 10 and a rear shaft 11 integrally having a tail plug portion, and an ink occlusion body 15 including a fiber bundle. , A relay core 20 made of a fiber bundle, an ink occlusion body 15 and a holding member 25 for holding the relay core 20, an ink guide tube 30, a pen tip 40 made of a fiber bundle, and a cap member 50. The cap member 50 includes an inner cap 51 and an outer cap 52.

The front shaft 10 is made of a synthetic resin or the like having visibility (transparent or translucent), and a small-diameter portion 10a having a tapered portion on the tip side and a large-diameter portion 10b are integrated. There is a structure in which the front portion of the ink guide tube 30 fitted with the pen tip 40 is mounted in the small diameter portion 10 a and the ink guide tube 30 is accommodated in the large diameter portion 10 b through the holding member 25. Yes.
As the front shaft 10, a synthetic resin having visibility (transparent or translucent), for example, a polyolefin resin such as polypropylene (PP), polyethylene (PE), cyclic polyolefin, poly (1-methyl-4-pentene), Polycarbonate (PC), polystyrene, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polyamide, and thermoplastic resin having visibility such as fluoroplastics such as fluororesin and vinylidene fluoride Can be used.

The outer peripheral surface of the small-diameter portion 10a of the front barrel 10 has a mating surface (mating portion) S ₁ the inner cap 51 of the cap member 50, fitting projections a, b are formed at predetermined intervals Yes. On the other hand, fitting protrusions c and d are also formed at predetermined intervals on the inner peripheral surface of the inner cap 51 of the cap member 50. The fitting projections c and d of the inner cap 51 get over the fitting projections a and b of the front shaft 10 so that the cap member 50 is fitted to the outer peripheral surface of the small-diameter portion 10a of the front shaft 10. is there.
Further, the rear side outer peripheral surface of the large diameter portion 10b of the front barrel 10 has a mating surface (mating portion) S ₂ a shaft 11 after the barrel, the fitting projection e is formed Yes. On the other hand, a fitting projection f is also formed on the inner peripheral surface of the rear shaft 11. The rear shaft 11 is fitted to the front shaft 10 by the fitting projection f of the rear shaft 11 getting over the fitting projection e of the front shaft 10.

In the present invention, as shown in FIG. 3, silicone cured polymer films are respectively applied to the fitting portion S _{1 on} the outer peripheral surface of the small diameter portion 10a of the tip shaft 10 and the fitting portion S ₂ on the outer peripheral surface of the large diameter portion 10b. It is formed.
The silicone cured polymer film formed on the fitting portions S ₁ and S ₂ is not particularly limited as long as it is a cured polymer film made of a silicone resin. For example, a silicone varnish having a dimethyl silicone is used. Can be mentioned. Examples of the curing mechanism of the silicone varnish include a condensation type, an addition type, and a UV type. Furthermore, the silicone varnish contains silica fine particles, and the acrylic resin contains dimethyl. Examples include those obtained by grafting silicone.

In the cured product of the silicone varnish constituting the silicone cured polymer film formed in the fitting portions S ₁ and S ₂ , the addition mold is excellent in that it has no by-product during curing and cures to a deep part. Further, the UV type has a short curing time and does not require heating, and therefore has excellent curing processing performance and handling performance. Further, the above condensation types include dealcohol, deoxime, deacetic, deamine, deamid, deamidoxy, deacetone, dehydrogenate, and dehydration types. There are types that cure with liquid or two liquids. As cured products of these silicone varnishes, a condensation type is preferred from the viewpoint of excellent workability, usability, cost, and strength, more preferably, even among cured products of silicone varnish, the strength is strong and the fitting force is most easily adjusted. A one-part deoxynium type is particularly desirable.

Further, the cured polymer film comprising silica fine particles in the silicone varnish can be made harder and stronger than the cured polymer film made of a cured silicone varnish alone. Silicone has essentially a low intermolecular force and an amorphous structure, so that its hardness and strength are slightly weak and the coating film may be easily broken. As a method for compensating for some of the drawbacks, hardness and strength can be improved by containing silica fine particles and the like. Silanol groups in the silica and the silanol groups after the silicone varnish are hydrolyzed and siloxane bonds by a dehydration condensation reaction and chemically bonded to improve hardness and strength.
Moreover, when using the silicone varnish containing the said silica fine particle, it is desirable to apply | coat after diluting the silicone varnish which a silica fine particle contains 1 to 10% with an organic solvent to 0.01 to 1% density | concentration. It is particularly desirable to use a silica varnish obtained after dilution in which the concentration of silica fine particles is 0.0001 to 0.1%, preferably 0.001 to 0.01%. Further, the silica is preferably amorphous silica.
As a material for forming these cured polymer films, specifically, X-31-608T (deoxynium type: containing 5 wt% of amorphous silica fine particles with respect to 20 wt% of silicone, manufactured by Shin-Etsu Chemical Co., Ltd.), SG-204 (polysiloxane graft polymer, manufactured by Nippon Shokubai Co., Ltd.), JS-025 (polysiloxane graft acrylic resin, manufactured by Nippon Paint Co., Ltd.), Teflon (registered trademark) AF1600 (manufactured by Mitsui DuPont Fluorochemical Co., Ltd.), Cytop TL110A CTL110S (Asahi Glass Co., Ltd.) or the like can be used.

Examples of a method for forming a silicone-cured polymer film on the fitting portions S ₁ and S ₂ include, for example, a silicone varnish (addition type, UV type, condensation type) having the dimethyl silicone or a silica fine particle, the graft Apply resin as it is, or by dissolving it in a solvent such as isohexane, methylcyclohexane, isopropyl alcohol / toluene mixed solvent, normal propyl alcohol, etc. A silicone-cured polymer film can be formed on at least a fitting portion between the cap and the front shaft of the writing instrument and the shaft tube by immersing the portion in each coating resin solution (dipping method) or the like.

In the present invention, in order to further strengthen the fitting portions S ₁ and S ₂ and to adhere the silicone cured polymer film, the silicone cured polymer film is formed after the surface of the fitting part is activated. The silicone cured polymer film may be formed after forming the adhesive layer on the surface, or the adhesive layer may be further formed after the surface activation treatment, and then the silicone cured polymer film may be formed.
Examples of the activation treatment include at least one activation treatment selected from ozone treatment, plasma treatment, corona treatment, ultraviolet irradiation treatment, high-pressure discharge treatment, and acid treatment.
Wood.
As ozone treatment, a member (including a shaft member) including fitting portions S ₁ and S ₂ to which a silicone cured polymer film is applied is placed in a container containing air, oxygen, nitrogen, carbon dioxide, argon, neon, etc., and glow discharge is performed. This is done by exposure to the plasma generated by The surface of the front shaft 10 is placed in a container containing oxygen, nitrogen, carbon dioxide, argon, neon, etc., and is exposed to plasma generated by glow discharge. In order to introduce functional groups such as carboxylic acid groups, carbonyl groups, amino groups, and the like, plasma discharge forms include DC discharge, low frequency discharge, radio wave discharge, microwave discharge, etc. It is not limited.

As the corona treatment, the fitting member surface can be activated by passing a front shaft member (fitting member) having a fitting portion in an electric field where corona discharge occurs.
As the ultraviolet irradiation treatment, the method of irradiating the surface of the fitting member with ultraviolet rays, when the surface of the fitting member is irradiated with ultraviolet rays, the ultraviolet ray is absorbed into a chemical structure such as a double bond in the surface region of the fitting member, The chemical bond is broken by the absorbed energy, and the purpose is to introduce carbonyl group, carboxyl group, etc. obtained by bonding oxygen in the air to the generated radical. A high pressure mercury lamp, an ultrahigh pressure mercury lamp, a xenon lamp, a metal halide lamp, or the like can be used, but is not particularly limited.
The high-pressure discharge treatment is a method in which a high voltage of several hundred thousand volts is applied between electrodes provided with a large number of fitting members, and the discharge is performed in the air. The discharge causes oxygen in the air and the surfaces of the fitting members to be discharged. When activated, oxygen is taken into the surface, and the surface of the fitting member can be activated by introducing a polar group.
The acid treatment can be performed by directly immersing the fitting member table in a chromium mixed acid solution, sodium hypochlorite / hydrochloric acid / water system, chlorate-sulfuric acid system, sulfuric acid, or the like.

  The adhesive layer improves adhesion with the fitting member and improves long-term durability. For example, a layer having a polysiloxane structure and a methyl methacrylate group is applied, or a metal alkoxide is applied by a sol-gel method. It can be formed by applying a solution obtained by hydrolysis and polycondensation and irradiating with ultraviolet rays.

The thickness of the silicone cured polymer film formed on the fitting portions S ₁ and S ₂ is preferably 0.02 to 200 μm, more preferably 0.05 to 50 μm. The formation of this thickness can be adjusted by changing the number of coatings, the concentration of the coating solution, and the like.
When the thickness of the cured polymer film of silicone is less than 0.02 μm, the effect of adjusting the fitting force is weak. On the other hand, when the thickness exceeds 200 μm, the fitting force is weakened.

In the writing instrument A of the embodiment configured as described above, a silicone cured polymer film made of silicone varnish or the like is formed on the fitting portions S ₁ and S ₂ between the cap and the front shaft of the writing instrument. Even if it does, the cured silicone polymer film that adjusts the fitting force does not peel off, and a writing instrument having an effect of adjusting the fitting force that is stable for a long period of time can be obtained.
Preferably, in the silicone cured polymer film comprising at least 0.1 to 10% by weight of silica fine particles in the ricone varnish forming the silicone cured polymer film, the writing instrument further has a stable fitting force adjusting effect. It can be.
Furthermore, after the surface of the fitting part is activated, a silicone cured polymer film is formed, or after forming an adhesive layer on the surface of the fitting part, a silicone cured polymer film is formed, and the surface of the fitting part is activated. In the case where the adhesive layer is further formed and the silicone cured polymer film is subsequently formed, the fitting portions S ₁ and S ₂ can be further strengthened, and the silicone cured polymer film can be closely adhered. Therefore, even if it repeats fitting, it can be set as the writing instrument which has the durability which the silicone cured polymer film does not peel and has the outstanding durability, and also the adjustment effect of the stable fitting force.

In this writing instrument A, as shown in FIGS. 1 to 4, the ink impregnated in the ink occlusion body 15 passes through the ink guide tube 30 through the relay core 20 and permeates the pen tip 40 and can be written. In addition, since the ink end sign from the ink occlusion body 15 can be detected by visually recognizing the ink guide tube 30 through the front shaft 10 serving as a visual recognition portion, the pen tip 40 In this case, it is possible to clearly and easily determine visually whether the ink scum is caused by drying at the nib 40 or due to the ink being consumed.
In addition, the air replacement accompanying the ink consumption is performed by passing through the air hole leading from the pen tip 40 and through the air passage inside the shaft tube to the pad end surface portion. Further, the end surface of the ink occlusion body 15 on the side where the ink guide tube 30 and the ink occlusion body 15 are joined is closed with respect to the outside air, and the O-ring 11 a Since the ink guide tube 30 is closed with respect to the outside air by being inserted through the ink, there is no inflow of outside air (air) into the ink guide tube 30 and the ink is interrupted by an impact such as a drop. It has a structure that does not happen.
Further, in the present embodiment, as shown in FIG. 2, since the tip shaft 10 is removable, the ink occlusion body 15, the relay core 20, the ink guide tube 30, the pen tip 40, and the like serving as the batting are cartridges. Therefore, the structure can be easily replaced and can be used again.

Writing instrument of the present invention is not limited to the above you施形state, it goes without saying that the change in various forms within the scope not changing the gist of the present invention.
Since the gist of the present invention is a structure formed by forming a silicone-cured polymer film on at least the fitting portion between the front shaft and the shaft cylinder of the cap and the writing instrument, the configuration not changing this gist is particularly limited. Instead, various known writing instrument structures can be used, and the pen tip and ink type can be applied to ballpoint pens, sign pens, marking pens, marking pens, white bird markers, writing pens, etc., to provide writing instruments suitable for various uses. It is something that can be done.
Furthermore, the present invention may be applied to applicators that use ink for writing instruments as liquid cosmetics such as correction liquids, coating liquids, and cosmetics.

  EXAMPLES Next, although this invention is demonstrated in detail based on an Example and a comparative example, this invention is not limited to the following Example.

[Examples 1-3 and Comparative Examples 1-3]
Use the Mitsubishi Pencil Whiteboard Marker (PWB-120, conforming to FIGS. 1 to 4) composed of a front shaft, a rear shaft, an ink holding member, an ink occlusion body, a pen tip, a cap member, an ink composition and the like having the following configuration. It was.
(1) Lead shaft 10 (fitting member)
Made of polypropylene (total light transmittance about 85%), large diameter part length 20mm, total length 36mm
(2) Ink occlusion body 15
Consists of polyethylene terephthalate (PET) batting (porosity 80%), diameter 12mm, length 65mm
(3) Relay core 20
Constructed from PET (porosity 60%), diameter 2.9 mm, length 22.5 mm, length 9.5 mm where rear end portion fits into ink occlusion body 15

(4) Ink guide tube length 36 mm, ink flow path volume about 89 mm ³
(5) Pen tip Consists of acrylic fiber sliver core (porosity 55%), length 15 mm
(6) Cap member Made of polypropylene (non-visibility), total length 32mm, outer cap inner diameter 15mm, inner cap inner diameter 0.9mm

(7) Ink composition [Ink composition (ink composition for whiteboard marker, 100% by weight in total)]
Carbon black M-800 4.9% by weight
Denkabutyral # -3000-4 4.9% by weight
Monoethanolamine salt of carboxylated polyoxyethylene lauryl ether 0.1% by weight
Polybutylene glycol distearate 11.7% by weight
Ethyl alcohol 63.7% by weight
n-propyl alcohol 14.7% by weight
Ink surface tension (25 ° C.) 22 mN / m, ink viscosity coefficient (25 ° C.) 5.5 mPa · s, impregnation amount into ink occlusion body 4 g

Example 1
Plasma treatment is applied to the outer peripheral surface of the front shaft to be a fitting member, and X-31-608-T (Oxium type: containing 5 wt% of amorphous silica particles with respect to 20 wt% of silicone, manufactured by Shin-Etsu Chemical Co., Ltd.) is 0 .05% diluted with xylene was applied by dipping method to volatilize the solvent, and then put into a dryer at 80 ° C. and heat treated for 3 hours to form a silicone cured polymer film on the fitting part S ₁ (Thickness 0.1 μm) was formed.
(Example 2)
In Example 1 described above, Example 2 was prepared using a 0.1% diluted solution.
(Example 3)
In Example 1 described above, Example 3 was prepared using a 0.025% diluted solution.

(Unprocessed product)
What did not process any front axis | shaft used as a fitting member was used.
(Comparative Example 1)
Mekuru the mating portion S ₁ of the front barrel to be fitted member (plus Inc., thickness 20 [mu] m) was used as the coated.
(Comparative Example 2)
Ethylene according to mating portion _{S 1} of the front barrel to be fitted member in Japanese Unexamined Utility Model Publication No. 55-83381 - vinyl acetate [(manufactured by Mitsui Poly Chemical Co.) El Pax 40 5%, 95% toluene, thickness 10μm ] Was used.
(Comparative Example 3)
Fitting member and comprising front barrel mating portion _{S 1} in JP-coated high polymer dimethylpolysiloxane solution at 20 ° C. kinematic viscosity 1000000 cst described in 8-300879 JP Example 1 (thickness 0.5 [mu] m) What was done was used.

Using the above Examples, Comparative Examples, and untreated products, the fitting force, sealing property, and durability test (appearance, fitting force, sealing property) were evaluated by the following methods.
These results are shown in Table 1 below.

[Measuring method of mating force]
Each of the above-mentioned Examples, Comparative Examples, and untreated product front shafts was used to produce whiteboard markers having the above-described configuration. The fitting force was measured by pulling the cap at a speed of 10 cm / min with an Imada push gauge (100 N) in a state where the cap was fitted to the pen, and measuring the maximum stress until the cap was pulled out.

[Evaluation method of sealability]
A hole was made in the pen cap, and a hose for flowing compressed air was connected to the hole. The pen body was placed in a water tank, and 0.05 MPas of compressed air was allowed to flow, and the presence or absence of air leakage was evaluated according to the following evaluation criteria.
Evaluation criteria:
○: No bubbles are generated.
Δ: Slight bubbles are observed.
X: Bubbles are generated vigorously.

  After removing the cap 1000 times, a sensory evaluation was made that the cured film was not peeled off visually, and the fitting force was measured and the sealing performance was evaluated in the same manner as described above.

As apparent from the results of Table 1 above, the writing instruments of Examples 1 to 3 that are the scope of the present invention are more effective for adjusting the fitting force than the writing instruments of Comparative Examples 1 to 3 that are outside the scope of the present invention. It was found that the durability was high and the sealing performance was also excellent.
When a comparative example etc. are seen individually, since an untreated product has too strong fitting force, there exists a weak problem in usability. In Comparative Example 1, it was found that by repeatedly removing and attaching the cap, the Mekool was wiped off, the fitting force was increased, and the appearance was also deteriorated. In Comparative Examples 2 and 3, the cured coating film peels off by repeatedly removing the cap, so that it is not possible to continue to maintain a good fitting force, and the sealing properties also deteriorate due to the coating film peeling off. It was.

It is a fragmentary longitudinal cross-section which shows the writing instrument of 1st Embodiment of this invention. It is a partial longitudinal cross-sectional view which shows the operation state which fits the front axis | shaft of the writing instrument used as 1st Embodiment to a shaft cylinder, and the operation state which fits a cap member to a front axis | shaft. In the writing instrument of 1st Embodiment, it is an expanded partial longitudinal cross-sectional view which shows the fitting part which forms a silicone cured polymer film in the front axis | shaft used as a fitting part with a cap and a shaft cylinder. It is a front view which shows the state which removed the cap in the writing instrument of 1st Embodiment.

Explanation of symbols

A Writing instrument S _{1 to} S ₄ Part for forming a silicone cured polymer film 10 Lead shaft 11 Rear shaft 12 Shaft cylinder 15 Ink occlusion body 20 Relay core 30 Ink guide tube 40 Pen tip 50 Cap member

Claims (5)

  A cap member, a shaft serving as a rear shaft for accommodating the ink occlusion body, a front shaft having a small diameter portion fitted to the cap member and a large diameter portion fitted to the shaft tube, and inserted into the front shaft The ink detector tube having visibility, the relay core supported by the ink detector tube and contacting the ink occluding body, and opposed to the relay core supported by the ink detector tube with a gap therebetween, A pen tip that is exposed from the tip shaft, and supplies the ink impregnated in the ink occlusion body in the shaft cylinder to the pen tip through the ink detector tube, and at the same time can visually recognize the ink end sign from the ink occlusion body In the writing instrument for detecting by visually recognizing the ink detector tube through the shaft, a fitting protrusion is formed on the outer peripheral surface of the small-diameter portion of the tip shaft on the surface to be fitted with the cap member, and the inner periphery of the cap member The cap member is formed with a fitting protrusion on the surface. The cap protrusion fits on the outer peripheral surface of the small diameter portion of the front shaft by the fitting protrusion on the peripheral surface over the fitting protrusion on the front shaft, and the fitting protrusion on the outer peripheral surface of the large diameter portion of the front shaft In addition, a rear end is fitted to the front shaft by forming a fitting protrusion on the inner peripheral surface of the rear shaft, and the rear surface fitting protrusion projects over the front shaft fitting protrusion. A silicone cured polymer film is formed on the inner peripheral surface of the cap, the outer peripheral surface of the small diameter portion of the front shaft, and the fitting portion between the outer peripheral surface of the large diameter portion of the front shaft and the inner peripheral surface of the shaft cylinder. Writing instrument characterized by that.   2. The writing instrument according to claim 1, wherein the silicone cured polymer film is formed by drying after applying a silicone varnish.   The writing instrument according to claim 2, wherein the curing mechanism of the silicone varnish is one of a condensation type, an addition type, and a UV type.   The writing instrument according to claim 2 or 3, wherein a silicone varnish containing 1 to 10% by weight of silica fine particles is applied. The writing instrument according to any one of claims 1 to 4 , wherein the silicone cured polymer film has a thickness of 0.05 to 200 µm.

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