JP2001205974A - Writing implement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a writing implement which is free of formation of bubbles in an ink accommodating part with elapse of time and is excellent in ink discharge properties. SOLUTION: The writing implement has the ink accommodating part formed in a vessel having a penpoint fitted to the fore end, and an ink composition and an ink backflow checking body are filled in the ink accommodating part. The ink composition contains at least a pigment, a dispersant, water and a water-soluble organic solvent having two or more hydroxyls in a molecule. The quantity of the organic solvent used herein is 40-70 wt.% to the whole quantity of the ink composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a writing instrument which does not generate air bubbles in an ink container over time and has an excellent ink discharge property.

[0002]

2. Description of the Related Art In a raw ink type writing instrument having an ink backflow preventive member at the rear end of an ink composition filled in an ink storage section, the ink composition is continuously discharged from a pen tip during writing, causing blurs and lines. Achieving continuous handwriting is an important quality. There are various causes for the occurrence of such blurring and broken lines. One of the causes is the presence of air bubbles in the ink composition. In other words, in a writing instrument, if air bubbles are present in the ink composition in the ink storage section, the movement of the ink is hindered by the air bubbles, and the supply of ink to the pen tip is reduced. May not be ejected and line breakage may occur. The main cause of the generation of air bubbles in the ink composition is that air is entrained in the ink composition at the time of manufacturing the ink composition or filling the ink container with the ink composition. Here, if the wettability between the inner surface of the ink container and the ink composition is poor, minute air particles adhere to the inner surface of the ink container and remain. On the other hand, since the gas component in the air is also dissolved in the ink composition, it is thought that the gas component collects in minute air particles adhered to the inner surface of the ink container over time and eventually grows as bubbles. Have been. Therefore, as a method for preventing the generation of these bubbles, a centrifugal force has been applied in the direction of the pen tip when filling the ink composition, thereby forcing the ink composition and the residual gas component to cause a specific gravity difference. A method of extruding minute air particles adhering to the inner surface of the ink container in the direction opposite to the pen tip has been adopted.

[0003]

However, even with the writing implement employing the above method, it is not possible to sufficiently remove fine air particles, and air bubbles are generated over a long period of time, resulting in blurred handwriting and lines. Had problems such as cutting. The present invention provides a writing implement that does not generate air bubbles in the ink composition over time and has excellent ink ejection properties.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a writing instrument comprising an ink container formed in a container having a pen tip attached to the tip, and an ink composition and an ink backflow preventer filled in the ink container. The ink composition contains at least a pigment, a dispersant, water, and a water-soluble organic solvent having two or more hydroxyl groups in a molecule, and the amount of the water-soluble organic solvent used is based on the total amount of the ink composition. A writing implement characterized in that the content is 40 to 70% by weight.

The details will be described below. A writing implement made by filling an ink composition into an ink storage section with a pen tip attached to the tip, and filling an ink backflow preventer at the rear end of the ink composition, uses a synthetic resin or metal cylinder as an ink. With a container, a pen tip consists of a chip with a ball placed at the tip, a so-called ball-point pen refill that is written by ink being transferred by the rotation of the ball, or a fiber core or plastic as a pen tip, and by capillary force There is a so-called marking pen which is written by discharging ink. The details of the ink composition to be filled in the ink storage section of these raw ink type writing instruments will be described below. The pigment is used as a colorant. The following can be illustrated as specific examples. Special Black 6,
S170, S610, 5, 5, 4, 4A, 55
0, 35, 250, 100, Printex 1
50T, U, V, 140U, 140V, 9
5, 90, 85, 80, 75, 55, 4
5, P, XE2, L6, L, 300, 3
# 0, # 3, # 35, # 25, # 200, #A, #G (all made by Degussa Japan KK), # 2400B, # 2
350, # 2300, # 2200B, # 1000, # 9
50, # 900, # 850, # MCF88, MA60
0, MA100, MA7, MA11, # 50, # 52,
# 45, # 44, # 40, # 33, # 32, # 30, C
F9, # 20B, # 4000B (Mitsubishi Chemical Industries, Ltd.), MONARCH 1300, MONARCH 1100,
1000, 900, 880, 800, 70
0, MOGUL L, REGAL 400R, 660
R, 500R, 330R, 300R, 99R,
ELFTEX 8, 12 and BLACK PEARLS
2000 (above, USA, Cabot Co. Ltd.
Manufactured), Raven7000, 5750, 5250,
5000, 3500, 2000, 1500, 1255, 1250, 1200, 1170, 1
060, 1040, 1035, 1020, 10
00, 890H, 890, 850, 790, 780, 760, 500, 450, 430, 420, 410, 22, 22, 16, 14, and 825
Oil Beads, H20, C, Conduc
carbon blacks such as tex 975, 900, and SC (all manufactured by Colombian Carbon Japan Co., Ltd.).

[0006] Kronos KA-10, 10P, 15
20, 20, 35, 60, 80, 90, K
R-310, 380, 460, 480 (all manufactured by Titanium Industry Co., Ltd.), P25 (Nippon Aerosil Co., Ltd.)
T-Tone SR-1, R-310, R-65
0, R-3L, A-110, A-150, R-
5N (all manufactured by Sakai Chemical Industry Co., Ltd.), Taipaque R-5
50, R-580, R-615, R-630, R-830, R-930, A-100, A-22
0, CR-58 (all manufactured by Ishihara Sangyo Co., Ltd.), Bayer Titanium R-FD-1, R-FD-2, R-FB-
1, the same R-FB-3, the same R-KB-3, the same R-CK-2
0 (above, manufactured by Bayer AG, Germany), Thai Pure R-90
0, R-901 and R-931 (both manufactured by DuPont Japan Limited), Titanics JR-3
00, JR-600A, JR-800, JR-8
Titanium oxide such as 01 (all manufactured by Teica Corporation). Super Fine No. No. 22000WN, the same No. 1800
0WN (all manufactured by Daiwa Metal Powder Co., Ltd.), WB023
0, WXM0630, WXMU75C, BS-605,
No. 607 (manufactured by Toyo Aluminum Co., Ltd.), bronze powder P-555, and bronze powder P-777 (manufactured by Nakajima Metal Foil Industry Co., Ltd.), AA12, No. 900, No. 1
8000, bronze powder-3L5, 3L7 (above,
Metal powder pigments such as Fukuda Metal Foil Industry Co., Ltd.). Inorganic pigments such as black iron oxide, yellow iron oxide, red iron oxide, ultramarine, navy blue, cobalt blue, chrome green, and chromium oxide.

C. I. Pigment Red 2, 3, 5, 17, 22, 22, 38, 41, 48: 2, 48: 3, 49, 50: 1, 53: 1, 57:
1, 58: 2, 60, 63: 1, 63: 2, 64: 1, 88, 112, 122, 123, 144, 146, 149, 166, 168, 170, 176, 177, 178, 179, 180, 185, 190, 194, 206, 207, 209, 216, 245, C.I. I. Pigment Orange 5, 10, 13, 13, 16, 36
40, 43, C.I. I. Pigment Violet 1
9, 23, 31, 33, 36, 38, 5
0, C.I. I. Pigment Blue 2, 15 and 15:
1, 15: 2, 15: 3, 15: 4, 15:
5, 15: 8, 16, 16, 17, 22, 25, 60, 66, C.I. I. Pigment Brown 25, 2
6, C.I. I. Pigment Yellow 1, 3, 12, 13, 24, 74, 83, 93, 94, 9
5, 97, 98, 99, 108, 109, 110, 117, 120, 139, 153, 166, 167, 173, C.I. I. Organic pigments such as CI Pigment Green 5, 7, 10, and 36;

In addition, inorganic fluorescent pigments such as zinc sulfide, zinc silicate, cadmium zinc sulphate, calcium sulfide, strontium sulfide, calcium tungstate, and other known organic fluorescent pigments can be used. The above pigments are
One or more kinds can be appropriately selected and used. The amount used is preferably 0.5 to 30% by weight based on the total amount of the aqueous pigment ink.

[0009] The dispersant is necessary for stably dispersing the pigment, and can be selected from resins conventionally used generally and various surfactants according to the pigment to be used. Examples of the resin include gum arabic, tragacanth gum, guar gum, xanthan gum, dextran, processed starch, glucosides such as saponin, cellulose derivatives such as methylcellulose, carboxycellulose and hydroxymethylcellulose, and lignin sulfonate. There are natural or semi-synthetic polymers such as shellac, and unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, and itaconic acid or alkyl esters thereof, and monomers selected from monomers such as styrene, acrylonitrile, and vinyl acetate. From the above-mentioned monomer group
Synthetic polymers obtained by selecting and co-polymerizing at least one kind are used in the form of an alkali metal salt, an ammonium salt, or an amine salt, and synthetic polymers such as polyvinyl alcohol, polyvinylpyrrolidone, and polyethylene oxide. These can be used in dissolved or emulsion form.

As various surfactants, anionic surfactants such as Demol EP and Homogenol L-
18, Poise 520, Poise 530 (all made by Kao Corporation)
And polyphthalic acid-type surfactants such as Demol N (manufactured by Kao Corporation) and the like, and naphthalene sulfonic acid formalin condensate-type surfactants such as Demol N (manufactured by Kao Corporation). Nonionic surfactants include Surfynol TG and 104E ( As described above, acetylene glycol-type activators such as Nissin Chemical Industry Co., Ltd., and polyoxyethylenes such as Pegnol O-6 (Toho Chemical Industry Co., Ltd.) and Neugen ET (Daiichi Kogyo Seiyaku Co., Ltd.) Alkyl ether type surfactant, Nonal 21
Polyoxyethylene alkyl phenyl ether type surfactants such as Nos. 0 and 212 (all manufactured by Toho Chemical Industry Co., Ltd.) and betaine type amphoteric surfactants.
One or more of these dispersants can be appropriately selected and used. The amount used is preferably 0.1 to 30 parts by weight based on 10 parts by weight of the pigment.

The water-soluble organic solvent having two or more hydroxyl groups in the molecule is used mainly for the purpose of suppressing the adhesion of minute air particles remaining in the ink composition to the inner surface of the ink container. Specific examples include ethylene glycol, diethylene glycol, propylene glycol, hexylene glycol, polyethylene glycol, thiodiethylene glycol, glycerin, sorbitan, and the like. One or more of these can be appropriately selected and used. The amount used should be 40 to 70% by weight based on the total amount of the ink composition. If the amount is less than 40% by weight, it is insufficient to prevent the generation of air bubbles. If the amount is more than 70% by weight, the pigment, dispersant,
Since the amount of water added is small, it is difficult to maintain physical properties suitable as an ink composition for a writing instrument.

Water is used as a solvent, and its amount is preferably 0.1 to 50% by weight based on the total amount of the ink composition.

Further, for the purpose of preventing the ink from freezing at low temperatures, glycol ether solvents such as ethylene glycol monophenyl ether and propylene glycol lower alkyl ether, and ester solvents such as ethyl acetate and ethyl lactate are used. Can also.

Further, as a viscosity modifier of the ink composition,
Natural or semi-synthetic water-soluble polymers such as gum arabic, gum tragacanth, guar gum, xanthan gum, dextran, processed starch, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, and synthetic water-soluble polymers such as polypyrylpyrrolidone, sodium polyacrylate, and polyethylene oxide A hydrophilic polymer or the like can also be used.

In addition, handwriting drying accelerators such as ethyl alcohol and isopropyl alcohol, rust inhibitors such as benzotriazole and ethylenediaminetetraacetate, urea,
Various additives such as wetting agents such as ethylene urea, preservatives such as benzothiazoline and omazine, antifoaming agents such as silicone surfactant, and leveling agents such as fluorine surfactant are appropriately selected. Can be used.

In producing the ink composition used in the present invention, various conventionally known methods can be employed. For example, each of the above components is blended, and the mixture is stirred and mixed by a stirrer such as a turbo mixer, a Henschel mixer, a homomixer, or uniformly mixed by a disperser such as a ball mill, an attritor, a sand grinder, a speed line mill, and a three-roll mill. It is easily obtained by dispersing.

The ink backflow preventive used in the present invention is used for the purpose of preventing evaporation of volatile components in the ink composition to be used and preventing the ink composition filled in the ink container from flowing out. Things. Specifically, a non-volatile organic liquid such as petrolatum, liquid paraffin, polybutene, α-olefin oligomer, ethylene-α-olefin oligomer, olive oil, or vegetable oil is used as a base material, and this base material is used as fine particle silica, hydrogenated castor oil. Gelling agents, cellulose gelling agents, dextrin gelling agents,
It is known to use a gelling agent such as metal soaps or bentonite.

There are various methods for filling the above ink composition and the ink backflow preventer into a writing implement. For example, one example is to put the produced ink composition into an ink container using a filling machine such as a syringe. The ink is then injected, and the ink backflow preventing body is similarly filled into the ink storage unit on the side opposite to the pen tip by a filling machine. After that, a ballpoint pen tip is set in the ink container, and a centrifugal force is applied in the direction of the pen tip to remove air existing between the ink composition and the ink backflow preventer, thereby performing centrifugal defoaming. .

[0019]

The reason why the writing implement of the present invention does not generate air bubbles in the ink storage portion with the passage of time and has excellent ink dischargeability is presumed as follows. The ink composition used in the writing instrument according to the present invention comprises a water-soluble organic solvent composition having two or more hydroxyl groups in a molecule, and an amount of 40 to the entire ink composition.
７０70% by weight. The water-soluble organic solvent having two or more hydroxyl groups in the molecule functions to improve the wettability between the inner surface of the ink container and the ink composition. Thereby, the adhesion force of the minute air particles entrained at the time of filling the ink to the inner surface of the ink storage portion is reduced. For this reason,
By centrifugal defoaming after filling the ink container with the ink composition and the ink backflow preventer, minute air particles in the ink container are easily removed, and fine air particles remaining in the ink composition are removed. The grains can be completely removed. Therefore, the writing implement manufactured by this, even over a long period of time, the aggregation of the gas components does not occur in the ink storage unit, without generating as bubbles, and by extension, an excellent writing implement that can maintain good writing dischargeability. Become.

[0020]

The present invention will be described below in more detail with reference to examples. Ink composition 1 WXMU75C (aluminum pigment, manufactured by Toyo Aluminum Co., Ltd.) 2.5 parts by weight WXM0630 (aluminum pigment, manufactured by Toyo Aluminum Co., Ltd.) 2.5 parts by weight Joncryl 450 (styrene acrylic emulsion, solid content 40) 24.0 parts by weight Xanthan gum 0.6 parts by weight Ethylene glycol 22.0 parts by weight Glycerin 22.0 parts by weight Proxel GXL (preservative, manufactured by Zeneca Corporation) 0.1% by weight Part Water 26.3 parts by weight Of the above components, each component other than xanthan gum was stirred with a propeller stirrer for 1 hour, xanthan gum was added, and the mixture was further stirred for 1 hour to obtain a metallic luster pigment ink composition.

Ink Composition 2 WXMU75C (aluminum pigment, manufactured by Toyo Aluminum Co., Ltd.) 5.0 parts by weight I. Pigment Yellow 83 4.0 parts by weight Joncryl 61J (styrene-acrylic acid copolymer, solid content 30.5% by weight, manufactured by Johnson Polymer Co., Ltd.) 10.0 parts by weight Xanthan gum 0.6 parts by weight Ethylene glycol 38.0 1 part by weight Glycerin 12.0 parts by weight Proxel GXL (preservative, manufactured by Zeneca Corporation) 0.1 part by weight Water 30.3 parts by weight After stirring each component other than xanthan gum among the above components with a propeller stirrer for 1 hour , Xanthan gum was added and the mixture was further stirred for 1 hour to obtain a yellow metallic luster pigment ink composition.

Ink composition 3 WB0230 (aluminum pigment, manufactured by Toyo Aluminum Co., Ltd.) 7.0 parts by weight C.I. I. Pigment Blue 15: 3 5.0 parts by weight Joncryl 450 (described above) 24.0 parts by weight Xanthan gum 0.6 parts by weight Diethylene glycol 60.0 parts by weight Proxel GXL (described above) 0.3 parts by weight Water 3.1 parts by weight described above After stirring each component of the components other than xanthan gum with a propeller stirrer for 2 hours, xanthan gum was added and the mixture was further stirred for 1 hour to obtain a blue metallic luster pigment ink composition.

Ink Composition 4 Super Fine No. 22000WN (aluminum pigment, manufactured by Daiwa Metal Powder Co., Ltd.) 7.0 parts by weight LUMIKOL NKW-2102 (green organic fluorescent pigment, solid content 54% by weight, manufactured by Nippon Fluorescent Chemical Co., Ltd.) 25.0 parts by weight Jonkrill 62 (styrene-acrylic acid copolymer, solid content 34% by weight, manufactured by Johnson Polymer Co., Ltd.) 17.0 parts by weight Propylene glycol 45.0 parts by weight Xanthan gum 0.5 parts by weight Proxel GXL (described above) 0.3 parts by weight Part Benzotriazole (rust inhibitor) 0.6 parts by weight Water 5.1 parts by weight Among the above components, each component other than xanthan gum is stirred for 1 hour with a propeller stirrer, and then xanthan gum is added and further stirred for 2 hours to obtain green. A metallic luster pigment ink composition was obtained.

Ink Composition 5 Kronos KR-380 (titanium oxide, manufactured by Titanium Industry Co., Ltd.) 13.0 parts by weight LUMIKOL NKW-2102 (described above) 21.0 parts by weight Demol EP (polycarboxylic acid type surfactant, 1.0 parts by weight Ethylene glycol 55.0 parts by weight Xanthan gum 0.5 parts by weight Proxel GXL (described above) 0.3 parts by weight Water 9.2 parts by weight Kronos KR-380 and Demol After uniformly mixing EP and 20 parts by weight of ethylene glycol, 3
This roll was passed 10 times, a liquid obtained by uniformly mixing the remaining components was added thereto, and the mixture was stirred for 1 hour with a stirrer.
A pastel green pigment ink composition was obtained.

Ink composition 6 C.I. I. Pigment Green 7 10.0 parts by weight John Krill 61J (described above) 8.0 parts by weight Kuraray Poval PVA203 (polyvinyl alcohol, manufactured by Kuraray Co., Ltd.) 11.0 parts by weight ethylene glycol 51.0 parts by weight thiodiethylene glycol 17.0 parts by weight Part Proxel GXL (described above) 0.3 part by weight Water 2.7 parts by weight Each of the above components was stirred with a propeller stirrer for 12 hours.
A green pigment ink composition was obtained.

Ink composition 7 PRINTEX 90 (carbon black, manufactured by Tegusa Japan K.K.) 5.0 parts by weight Joncryl 62 (described above) 10.0 parts by weight Nonal 212 (polyoxyethylene alkylphenyl ether type surfactant) 0.5 parts by weight Ethylene glycol 33.0 parts by weight Glycerin 15.0 parts by weight Proxel GXL (described above) 0.3 part by weight Water 26.2 parts by weight Each of the above-mentioned components is put into a propeller stirrer. And stir for 6 hours,
A black pigment ink composition was obtained.

Ink Composition 8 LUMIKOL NKW-2102 (described above) 21.0 parts by weight Demol EP (described above) 0.8 parts by weight Sorbitan 40.0 parts by weight Proxel GXL (described above) 0.3 parts by weight Water 37.9 parts by weight Part The above components were stirred for 4 hours with a propeller stirrer,
A green pigment ink composition was obtained.

Ink Composition 9 Ink composition 1 was prepared except that ethylene glycol and glycerin were added to ink composition 1 and water was added in the amounts.
In the same manner as in the above, a metallic luster pigment ink composition was obtained.

Ink Composition 10 A yellow metallic luster pigment ink composition was obtained in the same manner as in Ink Composition 2, except that glycerin was removed from Ink Composition 2 and water was added in the amount.

Ink Composition 11 A pastel green pigment ink composition was obtained in the same manner as in the ink composition 5, except that ethylene glycol was removed from the ink composition 5 and water was added in the same amount.

Ink composition 12 Ink composition 7 was prepared except that ethylene glycol and glycerin were added to ink composition 7 and water was added by the amounts.
In the same manner as in the above, a black pigment ink composition was obtained.

Ink backflow preventive body 1 Empara K43 (chlorinated paraffin, manufactured by Ajinomoto Co., Ltd.) 15.0 parts by weight Polybutene HV15 (manufactured by Nippon Petrochemical Co., Ltd.) 5.4 parts by weight Leopard KE (dextrin fatty acid ester, Chiba 0.5 parts by weight Aerosil R972 (fine particle silica, manufactured by Nippon Aerosil Co., Ltd.) 0.3 parts by weight The above components were mixed, and the mixture was stirred at 120 ° C. for 15 minutes with a hot stirrer to obtain a viscosity. An ink backflow preventive body 1 of 22,000 mPa · s (E-type viscometer, st rotor, 1 rpm, the same at 25 ° C. or less) was obtained.

Ink backflow preventer 2 Polybutene HV15 (described above) 17.5 parts by weight Leopard KE (described above) 1.2 parts by weight Aerosil R972 (described above) 1.3 parts by weight The above components were mixed, and heated to 120 ° C. with a hot stirrer. For 15 minutes to obtain an ink backflow preventive body 2 having a viscosity of 55000 mPa · s.

Example 1 A polypropylene pipe (having an inner diameter of 3.2 m) having a ballpoint pen tip comprising a 0.8 mm diameter ball (material: ceramic) and a stainless steel holder attached to one end.
m) was filled with the ink composition 1. Further, 0.1 g of the ink backflow preventive body 1 was filled in the upper part of the ink composition 1 (the side opposite to the ballpoint pen tip), and centrifugal defoaming was performed to prepare a ballpoint pen.

Example 2 A ballpoint pen was prepared in the same manner as in Example 1 except that the ink composition 2 was used instead of the ink composition 1.

Example 3 A ballpoint pen was prepared in the same manner as in Example 1 except that the ink composition 3 was used instead of the ink composition 1.

Example 4 A ballpoint pen was prepared in the same manner as in Example 1 except that the ink composition 4 was used instead of the ink composition 1.

Example 5 A ballpoint pen was prepared in the same manner as in Example 1 except that the ink composition 5 was used instead of the ink composition 1.

Example 6 A ballpoint pen was prepared in the same manner as in Example 1 except that the ink composition 6 was used instead of the ink composition 1.

Example 7 A polypropylene pipe having one end fitted with a fiber nib (material: polyester) and an elastic valve (material: EPDM) having a central portion provided with a slit through which ink flows only during writing. (Inner diameter: 6.8 mm) 2.5 g of the ink composition 7 and the ink backflow preventer 2 were filled and centrifugally defoamed to prepare a marking pen.

Example 8 A marking pen was prepared in the same manner as in Example 7, except that the ink composition 8 was used instead of the ink composition 7.

Comparative Example 1 A ballpoint pen was prepared in the same manner as in Example 1 except that the ink composition 9 was used instead of the ink composition 1.

Comparative Example 2 A ballpoint pen was prepared in the same manner as in Example 2 except that the ink composition 10 was used instead of the ink composition 2.

Comparative Example 3 A ballpoint pen was prepared in the same manner as in Example 1 except that the ink composition 11 was used instead of the ink composition 2.

Comparative Example 4 A marking pen was prepared in the same manner as in Example 7, except that the ink composition 12 was used instead of the ink composition 7.

Using the ballpoint pens and marking pens obtained in Examples 1 to 8 and Comparative Examples 1 to 4 as test samples,
A bubble generation confirmation test and an ink ejection property test were performed. Table 1 shows the results.

[0047]

[Table 1]

Test Method Bubble generation confirmation test After each test sample was allowed to stand for 10 days in a thermostat at 50 ° C with the pen pointed downward, the state of bubble generation at the interface between the ink composition in the ink storage unit and the ink backflow preventer Was visually checked. Evaluation criteria: ○: Almost no bubble generation is observed Δ: One bubble of about 0.5 mm is confirmed X: A plurality of bubbles of about 0.5 mm are confirmed. Alternatively, larger bubbles are observed.

2. Ink ejection test Rotation type continuous spiral writing tester (writing tester MODEL
Using TS-4C-20 (manufactured by Seiki Kogyo Kenkyusho), 100 m continuous writing was performed at a writing speed of 7 cm / sec, a load of 100 g, and a writing angle of 70 °. The weight change (g) before and after writing of the test sample was determined as the amount of ink consumed at that time.

[0050]

As described in detail above, the writing implement of the present invention does not generate air bubbles in the ink storage part with the passage of time, and is excellent in ink dischargeability.

Claims (4)

[Claims] 1. A writing instrument comprising an ink container formed in a container having a pen tip attached to a tip thereof, and an ink composition and an ink backflow preventer filled in the ink container.
The ink composition contains at least a pigment, a dispersant, water, and a water-soluble organic solvent having two or more hydroxyl groups in a molecule, and the amount of the water-soluble organic solvent used is based on the total amount of the ink composition. Writing instrument characterized in that the content is 40 to 70% by weight. 2. The writing implement according to claim 1, wherein the pen tip is a ballpoint pen. 3. The writing instrument according to claim 1, wherein the pen tip is a fiber core or a resin molded product. 4. The writing implement according to claim 2, wherein the pigment contains at least aluminum powder or titanium oxide.