JP2007021821A - Writing implement - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a writing implement which is equipped with an ink storage body of a type storing ink directly and enabling visual confirmation of the residual quantity of the ink from an outward appearance, wherein an ink-repellent layer excellent in close adhesion can be provided inside the ink storage body by a relatively inexpensive and easy method, without using any specific device, and which enables instantaneous visual confirmation of the residual quantity of the ink over a long time. <P>SOLUTION: The direct liquid type writing implement comprises the transparent or semitransparent ink storage body which directly stores the ink having a viscosity of 1-20 mPa s (25°C) and enables visual confirmation of the residual quantity of the ink from outside. The ink storage body is formed of a thermoplastic resin containing 0.01-10 mass% of a polymer surfactant having in a molecule at least one kind of hydrophilic group selected out of a carboxyl group and a sulfonic group, and the ink-repellent layer formed of a fluoroplastic having a perfluoroalkyl group is provided inside the body. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a direct liquid writing instrument of a type that can store ink directly and visually recognize the remaining amount of ink from the appearance.

  Conventionally, in writing instruments that discharge low-viscosity ink, such as fountain pens, ballpoint pens, and marking pens, there are two methods for storing ink: a direct liquid method in which ink is stored directly in the ink storage part, and ink that penetrates into the fiber converging body. A batting method for storing is known. Among these, the direct liquid method has an advantage that the remaining amount of ink can be visually recognized from the appearance by forming the ink storage portion with a transparent or translucent material.

  However, in the case of an ink using a solvent having a low surface tension such as alcohol as the main solvent, or an ink having a low surface tension due to the addition of a surfactant even if water is used as the main solvent, an olefin resin is used. Even if the ink reservoir is molded with a resin having a low critical surface tension as described above, the ink reservoir is wetted with the ink, so that the remaining amount of ink cannot be recognized instantaneously.

  In order to improve the remaining ink visibility of the direct liquid ink reservoir, the ink reservoir may be subjected to a liquid repellent treatment. A fluororesin having a perfluoroalkyl chain is effective for lyophobic liquid having a low surface tension. As a means for introducing a fluororesin having a liquid repellency into a thermoplastic resin generally used as a molding material for a writing instrument ink reservoir, a method of coating and drying the fluororesin liquid on the surface of the ink reservoir, There is a method of kneading a fluororesin into a resin forming an ink reservoir. Since the fluororesin is relatively expensive, it is preferable to use the fluororesin in a form in which the effect is manifested in a small amount. From this point of view, when these methods are compared, the method of kneading the fluororesin is not efficient because not all of the added fluororesins are distributed on the surface, whereas in the case of coating, the fluororesin layer is on the surface. Therefore, it is considered that the expected effect can be obtained efficiently.

  However, when coating is performed, the adhesion between the fluororesin layer and the substrate becomes a problem. In particular, in the case where the base material is a nonpolar material such as olefin, it is not possible to expect the adhesiveness due to electrostatic interaction, so the adhesiveness between the fluororesin layer and the base material is extremely weak. If the adhesion between the fluororesin layer and the substrate is poor, the resin layer will peel off and the effect will not continue. In order to improve the adhesion between the fluororesin layer and the substrate, surface modification of the substrate and a method of introducing an adhesive component between the fluororesin and the substrate are effective. As surface modification means, the surface of the base material is roughened by using sandpaper or sandblast, and the surface of the base material is activated by using corona discharge, plasma treatment, low wavelength UV irradiation, flame treatment, etc. Methods for introducing groups are known.

Patent Documents 1 to 4 disclose examples in which an ink repellent treatment with fluorine is performed in order to improve the ink remaining amount visibility of the writing instrument ink. Patent Document 1 proposes a writing instrument in which an ink repellent layer composed of an epoxy resin and a (meth) acrylic acid thermosetting resin having a perfluoroalkyl group is formed on the inner surface of an ink storage chamber formed of a thermoplastic resin. Has been. Patent Document 2 discloses a ballpoint pen in which an inner wall surface of an ink containing tube is formed at a fluorine interface. Regarding the adhesion of the ink repellent layer, Patent Document 4 considers the method of performing surface modification by performing an activation treatment such as plasma treatment or corona treatment, and Patent Document 3 considers the affinity with the fluororesin used. A method of providing an adhesive layer having a polysiloxane structure and methyl methacrylate is disclosed.
JP 7-81290 A JP-A-8-90982 JP 2002-293085 A JP 2005-81627 A

  However, although these methods can be said to be effective means for improving the adhesion between the fluororesin and the base material, special devices and processes are required, and further, processing is performed on the inner wall of the shaft-like ink reservoir. That itself is difficult.

  In view of the above-described conventional problems, the present invention includes an ink storage body of a type that can store ink directly and visually recognize the remaining amount of ink from the appearance, does not use a special device, and is relatively inexpensive inside. It is an object of the present invention to provide a writing instrument that can provide an ink-repellent layer with excellent adhesion by an easy method, and can instantaneously visually recognize the remaining amount of ink over a long period of time.

  As a result of intensive investigations on the above-mentioned problems of the prior art, the inventors of the present invention can directly store ink having a viscosity of 1 to 20 mPa · s (25 ° C.) and can visually check the remaining amount of ink from the outside. Alternatively, in a direct liquid writing instrument provided with a translucent ink reservoir, a special ink can be formed by molding the ink reservoir with a thermoplastic resin containing a polymeric surfactant having a carboxyl group or a sulfonic acid group in the molecule. Without using an apparatus, an ink-repellent layer having excellent adhesion can be provided in a relatively inexpensive and easy method inside the axial cylindrical ink reservoir, thereby improving the adhesion of the fluororesin, The inventors have found that the remaining amount of ink can be instantaneously recognized over a long period of time, and have reached the present invention.

  That is, the present invention directly stores ink with a viscosity of 1 to 20 mPa · s (25 ° C.), and includes a transparent or translucent ink reservoir that can visually recognize the remaining amount of ink from the outside. The ink reservoir is formed of a thermoplastic resin containing 0.01 to 10% by mass of a polymeric surfactant having at least one hydrophilic group selected from a carboxyl group and a sulfonic acid group in the molecule. And a writing instrument characterized in that an ink repellent layer made of a fluororesin having a perfluoroalkyl group is provided on the inner surface thereof.

  According to the present invention, the surface of a polypropylene resin or the like is hydrophilized by adding a polymer type surfactant to the thermoplastic resin forming the ink reservoir, so that the inside thereof can be obtained without using a special device. In addition, it is possible to provide a writing instrument that can provide an ink-repellent layer with excellent adhesion by a relatively inexpensive and easy method, and that can instantaneously visually recognize the remaining amount of ink over a long period of time.

  In addition, in addition to the above effects, the appearance of the appearance that occurs when the dye component moves to the shaft is added to the shaft-cylinder type direct liquid writing instrument and cartridge type writing instrument that can store ink directly and visually recognize the remaining amount of ink from the appearance. Deterioration and deterioration of visibility can be prevented. For example, a phenomenon in which the nigrosine black dye migrates during use and the shaft is yellowed or browned and the remaining amount of ink cannot be seen can be prevented.

Hereinafter, the present invention will be described in detail.
As the thermoplastic resin used in the ink reservoir for a writing instrument of the present invention, a resin having transparency or translucency is used in order to give visibility of the remaining amount of ink. Examples thereof include polypropylene, polyethylene, polycarbonate, polyvinyl chloride, styrene butadiene copolymer, ethylene butadiene styrene block copolymer, and ethylene vinyl acetate copolymer. In particular, in the case of a polyolefin resin having no polar group, since the electrostatic interaction with the fluororesin of the coating layer cannot be obtained and the adhesiveness when the treatment is not performed is low, the obtained effect is great.

  Depending on the type of thermoplastic resin, there is a phenomenon in which solvent molecules volatilized in the reservoir pass through the inside of the molded product and exit to the outside (hereinafter referred to as “permeation”). As a result, ink discharge from the pen tip becomes worse. Considering the permeability of the stored ink, it is desirable to use polypropylene as the thermoplastic resin. In particular, when a highly volatile compound such as ethanol, which has a relatively small molecular size and easily transmits, is used as the solvent constituting the ink to be stored, it is necessary to pay sufficient attention to this point.

  The polymer surfactant having in the molecule at least one hydrophilic group selected from the carboxyl group and sulfonic acid group used in the present invention has a carboxyl group, a sulfonic acid group, or a carboxyl group and a sulfonic acid group in the molecule. What is necessary is just to have. By adding this to the thermoplastic resin, the adhesiveness of the fluororesin to be coated by making the thermoplastic resin hydrophilic is increased, and the effect is maintained for a long time without peeling with time. Examples of the polymer surfactant include a copolymer of a monomer having a carboxyl group and / or a sulfonic acid group in the molecule and one or more other monomers, and post-carboxylation of the polymer. Examples thereof include a polymer having a carboxyl group or a sulfonic acid group introduced after sulfonation. These mass average molecular weights are preferably 4,000 to 15,000 in consideration of the moldability of the ink reservoir.

  Examples of the monomer having a carboxyl group include acrylic acid, methacrylic acid, maleic acid, maleic acid monoester, itaconic acid, itaconic acid monoester, and the like. Examples of the monomer having a sulfonic acid group include styrene derivatives having a sulfonic acid group such as styrene sulfonic acid and α-methylstyrene sulfonic acid, and olefin sulfones such as ethylene sulfonic acid, propylene sulfonic acid, and butylene sulfonic acid. Examples include acids and diene sulfonic acids such as butadiene sulfonic acid.

  The monomer copolymerized with the monomer is compatible with the thermoplastic resin serving as the base material of the ink reservoir, and may be anything as long as it does not impair the transparency of the ink reservoir. Examples thereof include vinyl arenes such as styrene, α-methyl styrene and vinyl toluene, olefins such as ethylene and propylene, and dienes such as butadiene and isoprene.

  Examples of the polymer suitable for sulfonation include styrene monomers such as styrene, α-methylstyrene, p-hydroxystyrene, vinyltoluene, or copolymers (for example, polystyrene, poly-α-methylstyrene, styrene-vinyl). Toluene copolymer), styrene-diene copolymer (for example, styrene-1,3-butadiene, styrene-isoprene copolymer), styrene-acrylic acid copolymer, styrene-acrylic acid ester copolymer (for example, Styrene-methyl methacrylate) and the like.

  Specific examples of the polymer surfactant include, for example, a styrene-acrylic acid copolymer, a styrene-maleic acid copolymer, a styrene-maleic acid monomethyl copolymer, a styrene-styrene sulfonic acid copolymer, and ethylene. Examples include acrylic acid copolymers, propylene-acrylic acid copolymers, ethylene-ethylene sulfonic acid copolymers, and propylene-ethylene sulfonic acid copolymers. Of these, styrene-acrylic acid copolymers are preferred.

  These polymer surfactants can be used alone or in combination. The amount used varies depending on the type of the polymeric surfactant, but is 0.01 to 10% by weight, preferably 0.05 to 5% by weight, more preferably 0.1 to 2% by weight, based on the total amount of the molded resin. It is. When the amount of the polymeric surfactant used is less than 0.01% by mass, the effect of improving the adhesion to the fluororesin cannot be obtained, and when it exceeds 10% by mass, there is a problem in molding the ink reservoir itself.

  As described above, by adding a small amount of high hydrophilic polymer to the molding resin, hydrophilic groups gather on the surface of the molded product and improve the polarity of the molded product surface. It is considered that the action is strengthened and the adhesion between the substrate and the coating layer is improved.

  In the writing instrument of the present invention, the ink repellent layer needs to be formed at least on the inner surface of the ink reservoir, but is formed on the surface of the ink reservoir (ie, the inner and outer surfaces) from the viewpoint of manufacturing convenience. May be. As a method of forming the ink repellent layer on the surface of the ink reservoir formed by molding the resin according to the above-described blending prescription, coating with a fluororesin solution is preferable from the viewpoint of workability and cost. As a fluororesin having a perfluoroalkyl group used for coating, for example, for coating such as FS-1010TH (manufactured by Fluoro Technology), FS-1020TH (manufactured by Fluoro Technology), ITN-332VC (manufactured by INT Screen) A fluororesin solution is mentioned. These fluororesin solutions can be coated on the ink reservoir by a method such as dipping, coating, or spraying, and the solvent can be dried to form an ink repellent layer.

  In the present invention, the ink reservoir produced by the above method directly stores ink for writing instruments having a viscosity of 1 to 20 mPa · s at 25 ° C., and allows the amount of ink remaining to be visually recognized from the appearance. The effect is greatly demonstrated by being mounted on the expression writing instrument. Therefore, the present invention can be applied to various types of writing instruments as long as the gist of the present invention is not changed. In particular, in the case of an ink having a low surface tension, since the remaining amount of ink is not very visible when the above treatment is not performed, it can be said that this problem is remarkably improved and more effective.

  The ink to be stored may be of any composition as long as it has a viscosity measured using an E-type viscometer of 1 to 20 mPa · s at 25 ° C. and 50 rpm. And adaptable to various forms. In the low-viscosity ink for writing instruments used for water-based ballpoint pens and marking pens, the ink viscosity is 1 to 20 mPa · s, which is a general value, and is slightly different depending on the form of the writing instrument such as the discharge part, but preferably 2 to 8 mPa · s. s. If the ink viscosity is less than 1 mPa · s (25 ° C), inconveniences such as leakage from the pen tip, blotting of the handwriting, and deterioration of fixability of the handwriting occur, and if it exceeds 20 mPa · s, ejection from the pen tip becomes worse. End up.

  In the present invention, examples of the writing instrument provided with the ink storage body include writing instruments having various ink discharge portions such as a fountain pen, a ballpoint pen, a refill for a ballpoint pen, a sign pen, a brush pen, and a marking pen.

  1 and 2 show an embodiment of the writing instrument of the present invention. FIG. 1 is a side sectional view showing an example of a water-based ballpoint pen equipped with an ink reservoir, and FIG. 2 is a side sectional view showing an example of an oil-based marking pen whose axis is an ink reservoir. 1 and 2, reference numeral 1 denotes a shaft, 2 denotes an ink discharge portion, 3 denotes a cross-sectional comb-like ink reservoir member, 4 denotes an ink guide core, 5 denotes an ink reservoir, and 6 denotes a cap.

  In the water-based ballpoint pen of FIG. 1, the ink reservoir 5 contains 0.01 to 10% by mass of a polymer surfactant having in the molecule thereof at least one hydrophilic group selected from a carboxyl group and a sulfonic acid group. An ink repellent layer made of a fluororesin having a perfluoroalkyl group is provided on the inner surface thereof. The ink discharge unit 2 is composed of a metal chip with a ball attached to the tip.

  In the oil-based marking pen of FIG. 2, the entire shaft 1 contains 0.01 to 10% by mass of a polymeric surfactant having at least one hydrophilic group selected from a carboxyl group and a sulfonic acid group in the molecule. An ink repellent layer made of a fluororesin having a perfluoroalkyl group is provided on the inner surface of the ink reservoir 5. The ink discharge part 2 is comprised with the fiber core.

  The above shows one example of a writing instrument provided with the ink reservoir of the present invention, and can be applied to various forms of writing instruments as long as the effects of the present invention are not impaired.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

(Examples 1-6, Comparative Examples 1-4)
An example of a direct liquid writing instrument provided with the ink reservoir of the present invention will be described. First, the following polymeric surfactant was added to the following thermoplastic resin in the formulation shown in Table 1 and kneaded to form an ink reservoir.
Thermoplastic resin A ... high density polyethylene (JT200, Mitsubishi Kasei Corporation)
Thermoplastic resin B ... Amorphous polypropylene (Novatech MG03B, Nippon Polychem Co., Ltd.)
Polymer surfactant A: Styrene-acrylic acid copolymer Mass average molecular weight: 11,000 (John Crill 815, Johnson Polymer Co., Ltd.)
Polymer surfactant B: Styrene-maleic acid copolymer (SMA1440H, ARCO chemical company)

  Next, the obtained molded body was immersed in a fluororesin solution for coating ITN-332VC (manufactured by INT Screen), coated with a fluororesin, dried to form an ink repellent layer, and heated at 80 ° C. for 5 hours. Heat-treated.

  Using the ink reservoir thus obtained, Examples 1 to 4 and Comparative Examples 1 and 2 show the water-based ballpoint pen shown in FIG. 1, and Examples 5 to 6 and Comparative Examples 3 to 4 show in FIG. An oil-based marking pen was assembled.

  The water-based ballpoint pen was tested using an aqueous pigment black ink (viscosity 4.62 mPa · s) and an oil-based marking pen using an oil-based dye black ink (viscosity 4.86 mPa · s).

(Evaluation methods)
(1) Formability was confirmed by visual observation of the shape of the ink reservoir after molding. At this time, it was evaluated as ◯ that could be molded without any problem, △ when the short shot was generated, and x when the surface condition was extremely bad and deformed.
(2) The stability over time was confirmed by visual observation of the remaining amount of ink after the writing instrument was allowed to stand at 50 ° C. for 2 weeks. At this time, when the remaining ink amount can be visually recognized within 10 seconds, the remaining ink amount can be visually recognized within 10 seconds, but when the ink repellent layer is partly removed, the ink is within 10 seconds. Those whose remaining amount could not be visually recognized were evaluated as x.

  The above evaluation results are shown in Table 1.

  As is clear from Table 1, the writing instrument provided with the ink reservoir of the present invention can provide an ink repellent layer having excellent adhesion by a relatively inexpensive and easy method without using a special device. It has become possible to visually recognize the remaining ink amount for a long time.

  On the other hand, a writing instrument provided with an ink reservoir formed of a resin to which no polymer surfactant is added or a resin whose content of the polymer surfactant is not within the range of 0.01 to 10% by mass is Stability was poor.

It is a sectional side view which shows an example of the water-based ball-point pen provided with the ink reservoir. It is a sectional side view which shows an example of the oil-based marking pen provided with the ink storage body.

Explanation of symbols

1 axis 2 ink ejection part (pen nib)
3 cross-sectional comb-like ink reservoir member 4 ink guide core 5 ink reservoir 6 cap

Claims (1)

In a direct liquid writing instrument having a transparent or translucent ink reservoir that can directly store ink having a viscosity of 1 to 20 mPa · s (25 ° C.) and visually recognize the remaining amount of ink from the outside,
The ink reservoir is formed of a thermoplastic resin containing 0.01 to 10% by mass of a polymer surfactant having in its molecule at least one hydrophilic group selected from a carboxyl group and a sulfonic acid group; A writing instrument comprising an ink repellent layer made of a fluororesin having a perfluoroalkyl group on its inner surface.

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