JPH025600B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a water-based ink metal tip ballpoint pen, and more specifically, the tip material is brass, which has good machinability and improved corrosion resistance to ink. This invention relates to an improved water-based ink metal tip ballpoint pen. Conventionally, resins such as polyacetal have been generally used as the tip material for water-based ink ballpoint pens, and there has been no problem of tip corrosion due to long-term contact with ink or being placed in an ink atmosphere. In addition, the ball used for the ball point of the pen nib has W, Co, and C as chemical components.
It is made of a cemented carbide ball, which is generally referred to as a cemented carbide ball, and is inherently less corrosive. Even when corrosion occurs depending on the type of ink, benzotriazole and sodium salt of ethylenediaminetetraacetic acid are used as rust preventive agents. The addition of these substances had a sufficient suppressing effect. The characteristics of these resin tip ballpoint pens are that they provide a very smooth writing feel and clear writing lines, but because of the resin tip, they are weak when writing with strong writing pressure, and the ball may fly off. It has poor pressure-sensitive copying properties that require such heavy writing. In addition, there are drawbacks such as difficulty in adapting to writing instruments that are becoming increasingly fine-grained.In recent years, metals such as stainless steel, brass, and nickel silver have been used as tip materials for water-based ink ballpoint pens. A water-based ink metal tip ballpoint pen capable of pressure-sensitive copying has been developed, but new problems have arisen because the tip material is metal. In other words, among the stainless steel chips, SUS304, SUS303, and
Corrosion-resistant stainless steels such as SUS316 have poor machinability, and free-cutting stainless steels such as SUS416, which have relatively good machinability, have the problem of being easily corroded by ink.
On the other hand, among copper alloys such as brass and nickel silver, so-called free-cutting brass and free-cutting nickel silver are generally used because they have good cutting properties, but because they are severely corroded by ink, rust preventive agents such as benzotriazole are used Although attempts have been made to suppress corrosion by adding it, the current situation is that sufficient rust prevention effects have not been achieved. Therefore, the object of the present invention is to improve the corrosivity caused by ink as a tip material, use brass with good machinability, and improve the corrosivity to the tip as a water-based ink without impairing the general performance of a water-based ink ballpoint pen. The present invention provides a water-based ink metal tip ballpoint pen with improved corrosion resistance over time. In order to complete the desired water-based ink metal tip ballpoint pen, the present inventors conducted fundamental research on corrosion in ink and metal, including the chemical composition of ink compositions and metal materials, ink compositions and metal crystal structures, and Ink composition and metal crystal grain size, etc.
Chemical structure of dyes and metal materials in ink compositions, inorganic salts and metal materials contained in dyes in ink compositions, types of water-soluble organic solvents and metal materials in ink compositions, inorganic salts in ink compositions We conducted research on the content, PH of metal materials and ink compositions, and corrosion of metal materials, etc., and also investigated the chemical composition and machinability of metal materials, the crystal structure of metal materials, crystal grain size, hardness, machinability, etc. As a result of extensive research into issues related to processability, the present invention has been completed. That is, the gist of the present invention is a water-based ink metal tip ballpoint pen characterized in that the tip material is brass that satisfies the following condition 1, and the ink is a water-based ink that satisfies the following condition 2. The specific conditions are shown in the following sections. Regarding brass <Condition 1> Among the chemical components, Cu component is 59-63%, Pb component is
1.8 to 3.7%, the metal crystal structure of brass is α single phase, the crystal grain size of brass is 0.015 mm or less, and the hardness of brass is Vickers hardness with a load of 5 kg.
Must be 150-200Kg/ ^mm2 . Regarding water-based inks <Condition 2> The dye is one or a mixture of two or more selected from azo dyes, xanthene dyes, and triphenylmethane dyes, sodium chloride, which is an inorganic salt contained in the dye, and /or the total content of sodium sulfate is
The total content of sodium chloride and/or sodium sulfate, which are inorganic salts, contained in the total amount of water-based ink must be 3000 ppm or less, and the water-soluble organic solvent must be ethylene glycol, diethylene glycol, propylene glycol, The ink must be one type or a mixture of two or more types of propylene glycol, the rust inhibitor must be benzotriazole and/or its derivatives, and the pH of the water-based ink must be 6.5 or higher. As described above, the present invention uses a material that satisfies <condition 1> as a chip material, and as a water-based ink,
By using a water-based ink that satisfies <Condition 2>, it is possible to provide a water-based ink metal tip ballpoint pen that satisfies the initial objective for the first time. Next, the chip material of the present invention, its corrosivity, and machinability will be explained. Table 1 summarizes representative examples of analytical values, corrosion resistance, and machinability of the characteristics of various brasses used as chip materials.

【table】

[Table] As shown in the previous table, commercially available free-cutting brass has a chemical composition of
It has a high Pb content, has a crystal structure consisting of both α and β phases, and has a Vickers hardness of 133 to 138 Kg/mm ² , so it has very good machinability, but with regard to corrosion, it has a high Pb content. Corrosion also occurred with the test ink to which benzotriazole, a rust inhibitor, was added because the β phase was included in the crystal structure. In addition, commercially available 6:4 brass has a low Pb content, which makes the metal sticky and has poor machinability, but the low Pb content and α single phase make it difficult to cut. , the corrosion resistance against ink compositions is good. According to the findings obtained from various tests conducted by the present inventors, including the above, in the case of brass, Pb in the chemical components of brass
The larger the amount, the better the machinability becomes, but the easier it is to corrode.Also, it is the Pb component and β phase that are corroded in the crystal structure, and if the Pb component is in a small amount, Although no effect on corrosivity was observed due to differences in grain size, it was found that as the Pb content increased and the grain size became smaller, corrosion did not occur. Furthermore, in terms of machinability, increasing the Pb content and hardness of 150Kg/mm ² to 200Kg/mm ² in terms of Vickers hardness at a 5Kg load, the metal tip ballpoint pen using water-based ink has good machinability. The inventors have discovered that the wear resistance of the chips is good, and have arrived at the present invention. Furthermore, each characteristic of the chip material will be explained in detail. Among the chemical components, the Cu component is 59-63%, and 63%
If it is above 59%, the material becomes tough and machinability is poor, and if it is less than 59%, the corrosion resistance against water-based inks is poor. The Pb component in the chemical components is 1.8-3.7% and 3.7%
If the content is above 1.8%, the machinability improves, but the corrosion resistance against water-based inks deteriorates, and if it is less than 1.8%, the machinability deteriorates. The optimum value for both machinability and corrosion resistance against water-based inks is 2.3 to 3.3%. In addition, Fe contained as an impurity in the same chemical component
The Sn component and the Sn component are preferably 0.5% and 0.8% or less, respectively, and if they are too large, they affect machinability and/or corrosion resistance against water-based inks. The metal crystal structure of brass, which is the chip material, is determined by the amount of Zn, which is the second component in the chemical components, and the conditions in the raw material processing process, but if there is a large amount of β phase, the corrosion resistance against ink will be poor. Therefore, α single phase is preferable. The crystal grain size of brass, which is a chip material, is 0.015 mm or less when the Pb component is limited to 1.8 to 3.7% in the metal chemical composition as in the present invention in order to improve machinability. This is important in terms of corrosion resistance against ink. If it is 0.015 mm or more, good corrosion resistance cannot be obtained. Furthermore, the hardness of brass, which is the chip material, has a very important meaning in terms of machinability and wear resistance of the chip. General free-cutting brass on the market has a Bitkers hardness of 130 to 140 at a load of 5 kg.
Good machinability can be obtained at Kg/mm ² , but when used in a water-based ink metal tip ballpoint pen, the contact area with the ball is generally made of cemented carbide due to the high speed rotation of the ball during normal writing. When the tip wears out, the ball may sink into the tip or fall off, making it impossible to write. In the present invention, by setting the hardness of the chip material to 150 to 200 Kg/ ^mm2 in terms of Vickers hardness at a load of 5 kg, it is possible to improve the machinability of the chip material and the wear resistance of the chip. Ta. If the Vickers hardness at a load of 5Kg is less than 150Kg/mm ² , the wear resistance of the chip is poor, and if it is more than 200Kg/mm ² , the chip material cannot be cut. Next, the water-based ink of the present invention will be explained in detail. There are various possible mechanisms of corrosion between water-based ink and brass, which is the chip material. Since the β phase, which has a high content of Zn, which is a more base metal, is anodic to the α phase, the β phase corrodes preferentially, and Zn removal occurs, causing corrosion. In the case of α single-phase brass, Zn removal occurs to a small extent. These Zn-free
The Zn component reacts with the dye in the ink, making the dye insoluble and forming a precipitate, which inhibits the rotation of the ball in a ballpoint pen, resulting in poor writing quality or even the inability to write. In addition, the Pb component, which is added as a free-cutting component to brass in addition to Zn-free corrosion, exists in the brass in the form of particles, and the Pb component is also preferentially corroded. In this case, desorption and corrosion occur on the surface as well as on the Zn component. In addition, Cu, the main component of brass,
Since it is a noble metal, desorption does not occur, but corrosion occurs on the surface. Corrosion of these metal components in brass on the metal surface is called rust, and it depends on the type of metal,
There are various reaction components, but the main ones include metal oxides, chlorides, and sulfides. It also creates a reaction product with the dye. In terms of functionality as a ballpoint pen, these products on the metal surface inhibit the rotation of the arrow ball, causing poor writing quality and impossibility of writing, as well as the appearance of the tip surface. This causes discoloration and a decrease in value. The inventors use it as a chip material. Regarding the corrosivity of brass, based on these theoretical findings, we also conducted various studies from the perspective of water-based inks.
Through intensive research and improvements in the chip material, we finally arrived at the present invention. Regarding water-based inks, various proposals have been made in the past, mainly rust preventive agents, but according to the knowledge of the present inventors, benzotriazole is the most effective rust preventive agent for brass, but in recent years it has also been used for writing instruments. Consumers' demands for quality have become higher and product warranty periods have become longer, and even in the water-based ink metal tip ballpoint pen of the present invention, the addition of benzotriazole alone is insufficient to guarantee the product for a long period of time. Of course, benzotriazole and/or its derivatives are also used as essential components in the aqueous ink of the present invention. Hereinafter, the water-based ink used in the present invention will be sequentially explained. First, the PH of the water-based ink is PH6.5.
The above conditions are optimal. If the pH is below 6.5, especially if acidic substances are present, corrosion will occur even if the chip material of the present invention is used. Some of the dyes used in the water-based ink of the present invention have a pH of 6.5 or lower, but in this case, it is necessary to adjust the pH to 6.5 or higher by adding an alkaline substance such as sodium hydroxide, sodium carbonate, or potassium hydroxide. be. Next, regarding the types of dyes, there are basic dyes, acid dyes, direct dyes, and food-grade dyes that are generally used in water-based inks for writing instruments. It cannot be used because it is difficult to dissolve at the high concentration required for water-based inks. It has been found that among acid dyes, direct dyes, and food colorings, the dyes that can be used in the water-based ink of the present invention can be classified according to the chemical structure of the dye. As a result of a corrosion test for brass, which is the chip material of the present invention, azo dyes, xanthene dyes, and triphenylmethane dyes were suitable. In the present invention, one kind or a combination of two or more kinds selected from these are used. Specific examples of azo dyes, xanthene dyes, and triphenylmethane dyes that can be used include the following:
The total content of sodium chloride and/or sodium sulfate, which are inorganic salts contained in the dyes defined in the present invention, must be 30,000 ppm or less. <Examples of azo dyes> Daiwa Yellow No. 4 (Color Index No.: Food Yellow 4, hereinafter abbreviated as CI) Water Yellow #1 (CI Acid Yellow 23) Daiwa Yellow No. 5 (CI Food Yellow 3) Direct First Yellow GC (CI Direct Yellow 14) Solar Light Orange GX (CI Acid Orange 10) Supranor Orange G (CI Acid Orange 56) Water Orange #18 (similar to CI Acid Orange 56) Daiwa Orange #100 (special azo type) Dyes) Direct First Orange S (CI Direct Orange 26) Daiwa Red No. 2 (CI Food Red 9) Daiwa Red No. 102 (CI Food Red 7) Water Red #1 (CI Assured Red 18) Solar Rubin Extra (CI Assured Red 14) Direct First Scarlet 4BS (CI Direct Red 23) Serious Red 4B (CI Direct Red 81) Kayanor Navy Blue R (CI Acid Blue 92) Direct Blue 2B (CI Direct Blue 6) Direct Sky Blue 5B (CI Direct Blue 15) ) Direct Dark Green B (CI Direct Green 1) Water Black #100-L (CI Direct Black 19) Direct Deep Black XA (similar to CI Direct Black 38) <Example of xanthene dye> Daiwa Red No. 3 (CI Food Red 14) ) Daiwa Red No. 103 (CI Assured Dred 87) Water Red #2 (CI Assured Dred 87) Daiwa Red No. 104 (CI Assured Dred 92) Water Pink #2 (CI Assured Dred 92) Daiwa Red No. 105 (CI Assured Dred 94) Eisen Assault Rhodamine BH (CI Assit Dred 52) <Examples of triphenylmethane dyes> Daiwa Purple No. 1 (CI Food Violet 2) Assit Violette 5B (CI Assit Violet 49) Daiwa Blue No. 1 (CI Food Blue 2) Water Blue #9 (CI Acid Blue 9) Spranol Blue B (CI Acid Blue 15) Orient Solble Blue OBC (CI Acid Blue 22) Water Blue #115 (CI Acid Blue
90) Daiwa Green No. 2 (CI Food Green 2) Daiwa Green #70S (Special triphenylmethane type) As mentioned above, in water-based inks, the corrosion of the chip material due to the difference in the type of dye has a large effect. Upon completion of the present invention, it was found that the content of sodium chloride and/or sodium sulfate, which are inorganic salts mixed as impurities, also has a great effect on the corrosion of the chip material. The total content of inorganic salts, sodium chloride and/or sodium sulfate, in the total amount of water-based ink must be 3000 ppm or less. Most of the inorganic salts, sodium chloride and/or sodium sulfate, in water-based inks are derived from dyes, and these inorganic salts are produced during the dye synthesis stage, and are normally added to dyes in large quantities. Mixed. In order to reduce the total content of inorganic salts such as sodium chloride and/or sodium sulfate in the aqueous ink to 3000 ppm or less, the dye used in the present invention is
In any dye, it is essential that the total content of these inorganic salts, sodium chloride and/or sodium sulfate, be 30,000 ppm or less. In addition, in normal ballpoint pen water-based inks,
Various water-soluble organic solvents are added as solubilizers for dyes, as anti-drying agents for ink at the ball point, and as anti-freeze agents for water-based inks in cold weather, but in the present invention, Ethylene glycol, diethylene glycol, propylene glycol, and dipropylene glycol are listed as water-soluble organic solvents that simultaneously satisfy these three functions and have the best corrosivity to chip materials.
They are used either as a species or as a combination of two or more species. Furthermore, the water-based ink of the present invention contains benzotriazole and/or its derivatives as an essential component as a rust preventive agent in order to maintain the initial quality of the water-based ink metal tip ballpoint pen over a long period of time. The present invention uses brass that satisfies the various physical properties described in this specification as the chip material, and furthermore limits the pH, dye, amount of inorganic salt, and water-soluble organic solvent in the water-based ink. In order to prevent corrosion of the tip of a ballpoint pen more reliably and for a longer period of time, the aqueous ink is characterized by containing benzotriazole and/or its derivatives. Benzotriazole and/or its derivatives are
Among the chemical components of brass, which is the chip material, it selectively reacts with the Cu component to form a strong monomolecular film of a chelate compound that is insoluble in water-based ink on the brass surface, inhibiting corrosion. The water in the aqueous ink composition preferably contains less ions that affect corrosion, such as chlorine ions and sulfate ions, and less ions that make dyes insoluble, such as calcium and magnesium. Specific examples include ion-exchanged water, Distilled water is preferred. The above-mentioned water-based ink dyes, water-soluble organic solvents,
The amounts of rust preventive and water used are 2.0 to 15.0% by weight, 3.0 to 50.0% by weight, 0.1 to 3.0% by weight, and 30.0 to 30.0% by weight, respectively.
95.0% by weight is preferred. The tip material and water-based ink of the water-based ink metal tip ballpoint pen of the present invention have been explained above, but as long as the water-based ink does not have a negative effect on the corrosivity of the tip material, adjustment of ink discharge and/or ink penetration into the writing paper. Addition of anionic and/or nonionic surfactants and/or water-soluble silicones for the purpose of adjustment, addition of preservatives and antifungal agents for the purpose of preventing rotting and mold formation of water-based ink, and prevention of ink drying at the pen tip. Addition of urea for this purpose and addition of lubricants for smooth rotation of the ball may be carried out as necessary. The present invention will be explained in more detail below using examples. Note that in Examples and Comparative Examples regarding water-based inks, parts simply refer to parts by weight. <Chip material used in Examples and Comparative Examples> In both cases, the chip material is a wire rod processed into a centerless material with a diameter of 2.5 mm.

[Table] Machinability tests were conducted on each chip material using a lathe. Further, from each of them, a ballpoint pen tip using a 0.6 mm diameter ball for water-based ink was prepared using an automatic tip processing machine, and used in Examples and Comparative Examples. <Water-based ink used in Examples and Comparative Examples>

【table】

[Table] Each of the water-based inks was prepared by gradually adding dyes and other additives to a mixed solution of water and a water-soluble organic solvent while stirring, and stirring for 2 hours. The inorganic salt content in the ink was measured by electrophoresis for both sodium chloride and sodium sulfate, and the total value was taken as the inorganic salt content. Also, the ink PH is PH
Measured with a meter. <Examples and Comparative Examples> After filling each ink for Examples and Comparative Examples using parts for normal water-based ink ballpoint pens other than the tip and ink, processing was performed using each tip material for Examples and Comparative Examples. The prepared metal tip was set on the shaft and assembled into a writable state to produce water-based ink metal tip ballpoint pens for use in Examples and Comparative Examples. Test results of Examples and Comparative Examples are shown below.

【table】

【table】

【table】

[Table] <Corrosion on the surface of the chip> Take the cap of the sample subjected to the forced aging test,
The corrosion state of the metal chip surface was observed using a microscope and judged based on the following criteria. ◎: No change at all from before the test 〇: The surface is cloudy and slightly discolored △: There is a little rust on the surface ×: There is a lot of rust on the surface <Writing performance> Samples subjected to forced aging test JIS, P3201 Handwritten notes were made on writing paper A, and judgments were made based on the following criteria. : No change at all from before the test〇 : Writing quality is slightly inferior △ : Writing quality is poor and the writing line becomes broken × : The ball does not rotate and writing is impossible (corrosion inside the tip) Samples subjected to forced aging test The metal chip was removed and the ball was removed by pressing it with a needle from the rear of the chip, and the state of corrosion inside the chip was observed under a microscope and judged using the same criteria as for ``corrosion on the surface of the chip.'' As shown in the results in the table above, the water-based ink metal tip ballpoint pen of the present invention has excellent machinability of the metal tip material and does not corrode even over a long period of time.

Claims (1)

[Scope of Claims] 1. A water-based ink metal tip ballpoint pen, characterized in that the chip material is brass that satisfies the following condition 1, and the ink is a water-based ink that satisfies the following condition 2. <Condition 1> Among the chemical components of brass, Cu content is 59-63%, Pb
The content of the brass must be 1.8 to 3.7%, the metal crystal structure of the brass must be α single phase, the crystal grain size of the brass must be 0.015 mm or less, and the hardness of the brass must be Vickers hardness with a load of 5 kg.
Must be 150-200Kg/ ^mm2 . <Condition 2> The dye is one or a mixture of two or more of azo dyes, xanthene dyes, and triphenylmethane dyes, and the total amount of inorganic salts such as sodium chloride and/or sodium sulfate contained in the dye is The content is
The total content of sodium chloride and/or sodium sulfate, which are inorganic salts, contained in the total amount of water-based ink must be 3000 ppm or less. The water-soluble organic solvent must be ethylene glycol, diethylene glycol, propylene glycol, or dipropylene. The ink must be one or a mixture of two or more glycols, the rust inhibitor must be benzotriazole and/or its derivatives, and the pH of the water-based ink must be 6.5 or higher.