JP5462751B2 - Ballpoint pen tip and ballpoint pen - Google Patents

Description

  The present invention relates to a ballpoint pen tip and a ballpoint pen, and more particularly to a ballpoint pen tip and a ballpoint pen having a ball covered with a carbonaceous film.

  A spherical ballpoint pen ball (hereinafter also simply referred to as a ball) is attached to the tip of a ballpoint pen used as a writing instrument. Writing is performed by the ink flowing out from the ink containing tube being transferred to a recording medium such as paper or penetrating by the rotation of the ball. When the ball and the ball holder that holds the ball are worn, the ball does not rotate smoothly, and the writing characteristics are greatly deteriorated, and finally, writing cannot be performed. For this reason, it is important to reduce the wear of the ball and the ball holder.

  In order to reduce ball wear, attempts have been made to use ceramic balls or to coat the surface of metal balls with a hard material. In addition, in order to reduce wear of the ball holder due to the ball, it has been attempted to coat not only the ball but also the ball holder with a hard material (see, for example, Patent Document 1).

JP 2004-338134 A

  However, it is difficult to reduce wear of the ball and the ball holder only by increasing the hardness of the ball and the ball holder. In order to reduce wear of the ball and the ball holder, it is important that an appropriate amount of ink is present at the interface between the ball and the ball holder, and the ball and the ball holder are not in direct contact with each other. When the affinity between the surface of the ball and the ink is low, the ink is repelled on the surface of the ball, and the ink cannot be held at the interface between the ball and the ball holder. In the conventional coating of the ball and the ball holder, the affinity with the ink is not considered, and there is a problem that the ball and the ball holder are in direct contact with each other and the ball and the ball holder are greatly worn.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and to realize a ballpoint pen tip that exhibits good writing characteristics over a long period of time, with which a ball and a ball holder are less likely to wear.

  In order to achieve the above object, the present invention is configured such that a ball-point pen tip has a carbonaceous film having a carbon-oxygen bond formed on at least one of a ball holder and a ball.

  Specifically, a first ballpoint pen tip according to the present invention includes a ball having a ball body and a carbonaceous film covering the ball body, and a ball holder that holds the ball rotatably. The carbonaceous film has carbon atoms and oxygen atoms bonded to carbon atoms, and the ratio of carbon atoms bonded to oxygen atoms on the surface of the carbonaceous film to all carbon atoms is 0.1 or more.

  In the first ballpoint pen tip, the ratio of carbon atoms bonded to oxygen atoms in the carbonaceous film covering the surface of the ball is 0.1 or more. For this reason, the surface of the ball has not only high hardness but also high affinity with ink. Therefore, an appropriate amount of ink can be held between the ball and the ball holder, and wear due to direct contact between the ball and the ball holder can be reduced. Accordingly, it is possible to realize a ball-point pen tip that is unlikely to deteriorate in writing characteristics over a long period of time.

  In the first ballpoint pen tip, the carbonaceous film may have a surface zeta potential of −25 mV or less. By doing so, the surface of the ball can be made sufficiently hydrophilic.

In the first ballpoint pen tip, the carbonaceous film may have a ratio of sp ³ carbon-carbon bond to sp ² carbon-carbon bond of 0.3 or more. By doing in this way, sufficient hardness can be ensured.

  In the first ballpoint pen tip, the ball has an intermediate layer formed between the ball main body and the carbonaceous film, and the intermediate layer may contain carbon and silicon.

  In the first ballpoint pen tip, the arithmetic average roughness on the surface of the ball main body may be 3 nm or less.

  In the first ballpoint pen tip, the ball holder may have a carbonaceous film covering at least a portion in contact with the ball. By doing in this way, wear of a ball holder can be reduced more.

  The second ballpoint pen tip according to the present invention includes a ball and a ball holder that holds the ball rotatably. The ball holder has a carbonaceous film that covers at least a portion in contact with the ball. The carbonaceous film has carbon atoms and oxygen atoms bonded to carbon atoms, and the ratio of carbon atoms bonded to oxygen atoms on the surface of the carbonaceous film to all carbon atoms is 0.1 or more.

  In the second ballpoint pen tip, the carbonaceous film may have a zeta potential of −25 mV or less. By doing so, the surface of the ball can be made sufficiently hydrophilic.

In the second ballpoint pen tip, the carbonaceous film may have a ratio of sp ³ carbon-carbon bond to sp ² carbon-carbon bond of 0.3 or more. By doing in this way, sufficient hardness can be ensured.

  In the second ballpoint pen tip, the carbonaceous film is formed on the surface of the ball holder via an intermediate layer, and the intermediate layer may contain carbon and silicon.

  The ballpoint pen according to the present invention includes the ballpoint pen tip of the present invention and an ink storage tube filled with ink, and the contact angle of ink on the surface of the carbonaceous film is 55 ° or less. By doing in this way, ink spreads enough on the surface of a ball, and it can be made hard to produce direct contact with a ball and a ball holder.

  With the ballpoint pen tip according to the present invention, it is possible to realize a ballpoint pen tip that is less likely to wear the ball and the ball holder and that exhibits good writing characteristics over a long period of time.

It is sectional drawing which shows the ball-point pen concerning one Embodiment. It is sectional drawing which shows the principal part of the ball-point pen tip concerning one Embodiment. It is sectional drawing which shows the cross section in the III-III line of FIG. It is a fragmentary sectional view showing a ball of a ball-point pen tip concerning one embodiment. It is a fragmentary sectional view showing the modification of the ball of the ball-point pen tip concerning one embodiment. It is sectional drawing which shows the principal part of the modification of the ball-point pen tip which concerns on one Embodiment. It is the result of the elemental analysis of the depth direction of the ball | bowl which formed the carbonaceous film. It is a table | surface which shows the specific example of the carbonaceous film | membrane which introduce | transduced the oxygen atom. It is a measurement result of the contact angle of ink. It is a result of the running test at the time of using water-based gel ink. It is a result of the running test at the time of using water-based gel ink. It is a result of the running test at the time of using oil-based ink. It is the result of the running test using water-based ink. It is the result of the running test at the time of forming a carbonaceous film on the ball holder side. It is the result of the running test at the time of forming a carbonaceous film on the surface of a ball body with different surface roughness. It is the result of the running test at the time of forming a carbonaceous film on the surface of a ball body with different surface roughness. It is the result of the running test at the time of forming a carbonaceous film on the surface of a ball body with different surface roughness. It is the result of the running test at the time of forming a carbonaceous film on the surface of a ball body with different surface roughness.

  As shown in FIG. 1, the ballpoint pen according to an embodiment includes an ink storage tube 10 that stores ink 15 and a ballpoint pen tip 20 that is attached to the tip of the ink storage tube 10. The ink storage tube 10 and the ballpoint pen tip 20 may be directly connected or may be connected via a connecting member (not shown). Moreover, although it is common to provide the case (not shown) which accommodates the ball-point pen refill which consists of the ink storage tube 10 and the ball-point pen tip 20, you may also set it as the structure where the ink storage tube 10 serves as a case. Is possible.

  As shown in FIG. 2, the ball-point pen tip 20 includes a ball 101 and a ball holder 111 that holds the ball 101. The ball holder 111 is made of a material such as ferritic stainless steel, and has a ball holding chamber 113 for holding the ball 101 and an ink passage 114 for supplying ink. The ball holding chamber 113 is a recess formed at the tip of the ball holder 111 and holds the ball 101 rotatably by the tip edge 118 and the bottom surface 116 of the ball holding chamber 113. The front edge 118 is caulked inward (in the direction of the center of the ball 101) at a predetermined caulking angle, and the ball 101 is rotatably held so that a part of the ball 101 protrudes from the front edge 118. In addition, the ball 101 is prevented from falling out of the ball holding chamber 113.

  FIG. 3 shows a cross section taken along the line III-III in FIG. In FIG. 3, the ball 101 is not shown. The ink passage 114 is provided at the center of the bottom surface 116 of the ball holding chamber 113, and serves as a main route when ink stored in the ink storage tube flows into the ball holding chamber 113 during writing. Around the ink passage 114, a plurality of grooves 115 provided radially with a predetermined width and interval are formed. At the time of writing, the ink that has passed through the ink passage 114 is supplied into the ball holding chamber 113 through the groove 115. A ball seat 117 is provided around the ink passage 114 on the bottom surface 116. The ball seat 117 is provided to suppress wear of the bottom surface 116 of the ball holding chamber 113 that is in contact with the ball 101 at the time of writing, and is formed in the same spherical shape as the ball 101.

  As shown in FIG. 4, the ball 101 has a ball main body 102 and a carbonaceous film 103 formed on the ball main body 102. The material of the ball body 102 is not particularly limited, and may be, for example, a simple substance of various metals, an alloy, ceramics, or the like. Specifically, a single metal such as steel, copper, aluminum or nickel may be used, or an alloy such as white or stainless steel may be used. Further, carbides such as metals, oxides, nitrides, borides, or suicides can be used. As the carbide, a carbide such as titanium, vanadium, chromium, tantalum, niobium, molybdenum, boron, zircon, tungsten, or silicon can be used. As the oxide, an oxide such as aluminum, chromium, magnesium, silicon, beryllium, thorium, titanium, calcium, or zircon can be used. As the nitride, a nitride such as titanium, boron, silicon, or aluminum can be used. As the boride, borides such as zircon, chromium or titanium can be used. As the silicide, a silicide such as molybdenum, titanium, or chromium can be used. Alternatively, a composite material of a metal such as cermet and ceramics may be used. The diameter of the ball body is not particularly limited, but is generally about 0.25 mm to 2.0 mm.

The carbonaceous film 103 is a film containing sp ² carbon-carbon bonds (graphite bonds) and sp ³ carbon-carbon bonds (diamond bonds), which are typified by diamond-like films (DLC films). It may be an amorphous film such as a DLC film or a crystalline film such as a diamond film. Usually, it contains sp ² carbon-hydrogen bonds and sp ³ carbon-hydrogen bonds, but carbon-hydrogen bonds are not essential components. Further, silicon (Si), fluorine (F), or the like may be added. In order to improve the affinity between the ball 101 and the ink, the carbonaceous film 103 according to the present embodiment includes carbon-oxygen bonds at least on the surface thereof. The ratio of carbon atoms forming carbon-oxygen bonds on the surface of the carbonaceous film 103 to all carbon atoms is preferably 0.1 or more. The carbon-oxygen bond ratio will be described in detail later.

  The carbonaceous film 103 may be formed by a plasma chemical vapor deposition method (plasma CVD method) or a catalytic chemical vapor deposition method (CAT-CVD method) using a hydrocarbon gas as a raw material. Further, it may be formed by a sputtering method using a solid graphite as a raw material, an arc ion plating method, or the like. Furthermore, it may be formed by other methods, or may be formed by combining a plurality of methods.

  The introduction of carbon-oxygen bonds to the surface of the carbonaceous film 103 may be performed by irradiation with oxygen plasma or plasma of a gas containing oxygen, for example. Water vapor, air, or the like may be used as the gas containing oxygen. A gas such as an organic compound containing an oxygen atom can also be used. Furthermore, the carbonaceous film may be irradiated with ultraviolet rays in an atmosphere containing oxygen, or the carbonaceous film may be immersed in an oxidizing solution. Further, by increasing the oxygen concentration in the atmosphere when forming the carbonaceous film 103, it is possible to introduce carbon-oxygen bonds when forming the carbonaceous film. Immediately after the formation of the carbonaceous film, dangling bonds are present on the surface. For this reason, it is possible to introduce a carbon-oxygen bond by allowing the dangling bonds and oxygen to react by leaving the carbonaceous film immediately after deposition in an atmosphere containing oxygen.

  The film thickness of the carbonaceous film 103 is preferably in the range of 0.001 μm to 3 μm, and more preferably in the range of 0.005 μm to 1 μm. The carbonaceous film 103 can be directly formed on the surface of the ball main body 102, but in order to make the ball main body 102 and the carbonaceous film 103 more firmly adhere to each other, as shown in FIG. An intermediate layer 105 may be provided between the material film 103. Various materials can be used as the material of the intermediate layer 105 depending on the type of the ball body 102, but silicon (Si) and carbon (C), titanium (Ti) and carbon (C), or chromium (Cr). A known film such as an amorphous film made of carbon (C) can be used. Although the thickness is not specifically limited, the range of 0.001 micrometer-0.3 micrometer is preferable, More preferably, it is the range of 0.005 micrometer-0.1 micrometer. The intermediate layer 105 may be formed using, for example, a sputtering method, a CVD method, a plasma CVD method, a thermal spraying method, an ion plating method, or an arc ion plating method.

  The ball-point pen tip of this embodiment has a carbonaceous film 103 having a carbon-oxygen bond in which a ball 101 is formed on the surface of the ball main body 102. For this reason, the ball 101 has not only high durability but also high affinity between the ball 101 and ink. For this reason, ink is held at the interface between the ball 101 and the ball holder 111, and direct contact between the ball 101 and the inner wall surface of the ball holder 111 is less likely to occur. Therefore, it is possible to reduce the wear of the ball 101 and the ball holder 111 due to the direct contact between the ball 101 and the ball holder 111, and it is possible to realize a ballpoint pen that is excellent in durability and hardly causes deterioration in writing quality due to use. . Further, since the ink supply can be stabilized by improving the affinity between the ball 101 and the ink, more uniform handwriting and drawing can be realized. Ballpoint pen inks are mainly classified into water-based inks, water-based gel inks, and oil-based inks. Oil-based inks for ballpoint pens generally contain a component having a hydrophilic functional group such as an alcohol or glycol ether as a solvent. For this reason, the introduction of the carbon-oxygen bond into the carbonaceous film 103 can improve the durability and feeling of use not only for the water-based ink and water-based gel ink for ballpoint pens but also for the oil-based ink for ballpoint pens. it can.

  Since the ball-point pen tip of this embodiment has high affinity between the ball 101 and the ink, even when the ball holder 111 is formed of a general material, wear of the ball 101 and the ball holder 111 can be reduced. Wear of the ball 101 and the ball holder 111 can be further reduced by forming a carbonaceous film similar to the ball 101 on at least a portion of the ball holder 111 that contacts the ball 101. For example, by forming a carbonaceous film on the surface of the ball seat 117, it is possible to further reduce wear of the ball 101 and the ball holder 111. Moreover, as shown in FIG. 6, it is good also as a structure by which the carbonaceous film 121 was formed so that surfaces, such as the front-end | tip edge part 118 and the bottom face 116, may be covered. A carbonaceous film may also be formed outside the ball holder 111. Furthermore, a carbonaceous film may also be formed on portions other than the ball holder 111 of the ballpoint pen tip 20. Further, when a carbonaceous film is formed on the ball holder 111, a normal ball that is not covered with the carbonaceous film may be used.

  The carbonaceous film 121 formed on the ball holder 111 and the carbonaceous film 103 formed on the surface of the ball 101 may have the same introduction amount of functional groups. In addition, carbonaceous films having different amounts of introduced functional groups may be formed on the ball holder 111 and the ball 101.

  Next, the present invention will be described in more detail with reference to examples. The present invention is not limited to the following examples, and various improvements and design changes may be made without departing from the spirit of the present invention.

-Ball manufacturing method-
Tungsten carbide (WC, equivalent to ISO K-10) was used as the ball body. The diameter of the ball body was 0.5 mm or 0.7 mm. First, an intermediate layer (not shown) made of an amorphous film containing Si and C was formed on the surface of the ball body. An ionized vapor deposition method was used for film formation. The inside of the chamber for ionization deposition is adjusted to a predetermined pressure using a vacuum pump, and tetramethylsilane (Si (CH ₃ ) ₄ ) is introduced into the chamber, and a bias voltage of 1 kV is applied to the ball for 30 minutes. Discharge was performed. By rotating the ball body in the chamber during film formation, an intermediate layer was formed on the entire surface of the ball body.

  After the formation of the intermediate layer, the gas supplied into the chamber was changed to benzene in the case of DLC-1, and changed to acetylene in the case of DLC-2 to form a carbonaceous film. In the case of DLC-1, the inside of the chamber was adjusted to a predetermined pressure using a vacuum pump, and then a bias voltage of 1 kV was applied to the ball to discharge for 90 minutes. In the case of DLC-2, after the discharge was completed, the plasma was switched to plasma using a high frequency power source, and film formation was further performed under a pressure of 10 Pa for 60 seconds. A carbonaceous film was formed on the entire surface of the ball body by rotating the ball body in the chamber during film formation.

  Thereafter, plasma irradiation was performed in an atmosphere containing oxygen to introduce carbon-oxygen bonds into the carbonaceous film. In the plasma irradiation, the pressure in the chamber was adjusted to 100 Pa, the output was 10 W in the case of DLC-1, and the output was 50 W in the case of DLC-2.

-Evaluation method of carbonaceous film-
The composition of the obtained carbonaceous film was evaluated by X-ray photoelectron spectroscopy (XPS) measurement. The XPS measurement conditions were such that the detection angle with respect to the sample was 90 °, Al was used as the X-ray source, and the X-ray irradiation energy was 100 W. The time for one measurement was 0.1 ms, and one sample was measured 64 times.

The carbon 1s (C1s) peak obtained by XPS measurement is represented by sp ³ C—C and sp ² C—C in which carbons are bonded together, sp ³ C—H and sp ² C—H in which carbon and hydrogen are bonded, It was decomposed by curve fitting into seven components of C—O, C═O and O═C—O in which carbon and oxygen were bonded. The bond energy of sp ³ C—C is 283.8 eV, the bond energy of sp ² C—C is 284.3 eV, the bond energy of sp ³ C—H is 284.8 eV, and the bond energy of sp ² C—H is 285. The bond energy of 3 eV and C—O was 285.9 eV, the bond energy of C═O was 287.3 eV, and the bond energy of O═C—O was 288.8 eV. The value obtained by dividing the area of each peak obtained by curve fitting by the area of the entire C1s peak was taken as the composition ratio of each component. The sum of the composition ratios of C—O, C═O, and O═C—O was _{defined as the} ratio (CO _total ) of carbon atoms bonded by carbon-oxygen to all carbon atoms.

  The film thicknesses of the carbonaceous film and the intermediate layer were obtained by etching by Auger electron spectroscopy and performing elemental analysis in the depth direction. In Auger electron spectroscopy analysis, the acceleration voltage of the electron gun was 10 kV, the sample current was 500 nA, and the acceleration voltage of the argon ion gun was 2 kV. Analysis in the depth direction was performed on a 40 μm square region.

  For the contact angle measurement, an automatic contact angle measuring machine (DM-500 manufactured by Kyowa Interface Science Co., Ltd.) was used. 1 μl of ink was dropped on the surface of the carbonaceous film, and the contact angle was measured. The measurement timing was immediately after dropping in the case of water-based ink, and 3 seconds after dropping in the case of water-based gel ink and oil-based ink having high viscosity. The measured value was an average value of three points.

  For the measurement of zeta potential, monitoring particles (manufactured by Otsuka Electronics Co., Ltd.) dispersed in a 10 mM sodium chloride (NaCl) solution using a zeta potential / particle size measurement system (ELS-Z: manufactured by Otsuka Electronics Co., Ltd.) Was used. The monitor particles were electrophoresed at each level in the cell depth direction, and the apparent velocity distribution inside the cell was measured. Electrophoresis was performed under the conditions of an average electric field of 17.33 V / cm and an average current of 1.02 mA. By analyzing the apparent velocity distribution obtained based on the Mori-Okamoto equation, the surface potential of the carbonaceous film surface was obtained.

-Durability evaluation method-
A ball on which a carbonaceous film having a carbon-oxygen bond was formed was mounted on a ball holder of a commercially available ballpoint pen (Pilot Corporation), and a running test was performed. The material of the ball holder was ferritic stainless steel. In the running test, the ballpoint pen is held in a state inclined at 70 degrees with respect to the paper surface, rotated so as to draw a circle having a diameter of 32 mm, and the writing paper (JIS: P3201) is moved at a speed of 4 m / min. This is a test to check the writing distance of a ballpoint pen using The ballpoint pen draws a circle and writes a distance of about 10 cm. The distance from the ball holder to the ball tip position was measured every 100 m of the writing distance. Since the distance from the ball holder to the ball tip position is reduced due to wear of the ball and the ball holder, the amount of change (sink amount) of the ball tip position is defined as the wear amount.

-Evaluation results-
FIG. 7 shows the results of Auger electron spectroscopy analysis of the ball on which the carbonaceous film is formed. It is clear that only carbon atoms (C) are present at a depth of about 80 nm from the surface, and a carbonaceous film is formed. It is clear that Si atoms are present at a depth of 80 nm to 120 nm, and an intermediate layer made of SiC is formed. A ball body made of tungsten carbide (WC) is detected at a depth of 100 nm or more.

A carbon-oxygen bond was introduced to the surface of the carbonaceous film by irradiating the carbonaceous film with oxygen plasma. By changing the plasma irradiation conditions, two types of carbonaceous films having different carbon-oxygen bond ratios were obtained as shown in FIG. In FIG. 8, C—C is the sum of sp ³ C—C and sp ² C—C, and C—H is the sum of sp ³ C—H and sp ² C—H. In DLC-1, the output of the high-frequency power source was 10 W, and oxygen plasma was irradiated for 60 seconds. In DLC-2, the output of the high frequency power source was 50 W, and oxygen plasma was irradiated for 60 seconds. The ratio of carbon atoms bonded to oxygen atoms to all carbon atoms (CO _total ) was 0.16 for DLC-1 and 0.43 for DLC-2. The value of CO _total of DLC-2 having a higher power output when irradiating oxygen plasma was higher than that of DLC-1. When CO _total is examined in more detail, the ratio of C—O to the total carbon is almost the same in DLC-1 and DLC-2, but the ratio of C═O is about DLC-1 in DLC-2. The ratio of O = C—O was about 9 times that of DLC-1 in DLC-2.

  The ink for ballpoint pens mainly comprises a dye or pigment as a colorant and a solvent, and in the case of water-based gel ink, it further contains a thickener. In the case of water-based ink and water-based gel ink, the solvent is mainly water. For this reason, the affinity between the carbonaceous film and the ink is higher when the surface of the carbonaceous film is somewhat hydrophilic. In addition, since the organic solvent of the oil-based ink contains a component having a hydrophilic functional group such as alcohol or glycoether, it is more preferable that the surface of the carbonaceous film is somewhat hydrophilic. It is thought that the affinity with ink increases.

C—O having a composition determined by XPS mainly comprises hydroxyl groups and ethers, C═O mainly comprises carbonyl groups and ketones, and O═C—O mainly comprises carboxyl groups and esters. It is thought that it is composed. For this reason, it is considered that as the value of CO _total increases, the hydrophilicity on the surface of the carbonaceous film increases and the affinity between the carbonaceous film and the ink increases. The value of CO _total may be at least 0.1 or more. However, if the value of CO _total becomes too large, the bond between carbons decreases and the hardness decreases, so 0.5 or less is preferable.

FIG. 9 shows the results of measuring the contact angle for water-based ink, water-based gel ink, and oil-based ink. The water-based ink used is a commercially available ink (manufactured by Pilot Corporation) consisting of an organic solvent, water and a water-soluble dye-based colorant. The viscosity in an environment of 20 ° C. is 1 to 2 mPa · s. The water-based gel ink is an ink used for a commercially available gel ink ballpoint pen (manufactured by Pilot Corporation: G-2). Contains an organic solvent, a water-soluble dye-based colorant, a shear thinning agent, a moisturizing wetting agent and water. Under an environment of 20 ° C., the viscosity at a shear rate of 384.0 seconds− ¹ is 50 mPa · s. The oil-based ink is obtained by reducing the viscosity of an ink used in a commercially available oil-based ballpoint pen (manufactured by Pilot Corporation). In the case of oil-based inks, the lower the viscosity, the greater the wear on the ball seat, so the low viscosity ink was used. Includes organic solvents such as phenyl glycol and benzyl alcohol, oil-soluble dye-based colorants, resins, lubricants, viscosity modifiers, and the like. The viscosity in an environment of 20 ° C. is 1500 mPa · s. In addition, the digital viscometer (Brookfield company DV-II: CPE-42 rotor) was used for the measurement of a viscosity.

  As a control, measurement was also performed on a tungsten carbide (WC) ball on which no carbonaceous film was formed. For any of the water-based ink, water-based gel ink, and oil-based ink, the contact angle of DLC-1 was smaller than that of WC, and the contact angle of DLC-2 was further decreased. In the case of water-based ink, the contact angle, which was about 60 ° for untreated WC balls, is reduced to about 55 ° for DLC-1 and about 3 ° for DLC-2. You can see that Also for the water-based gel ink, the contact angle, which was about 44 ° with the untreated WC ball, became 39 ° with DLC-1, and decreased to about 22 ° with DLC-2. In the case of oil-based inks, the contact angle, which was about 32 °, has decreased to about 25 ° and 20 °. In either ink, the ink is formed by forming a carbonaceous film having a carbon-oxygen bond. It is clear that the affinity with is improved.

  It is considered that when a carboxyl group is generated by introducing a carbon-oxygen bond, the zeta potential on the surface of the carbonaceous film is lowered. The zeta potential in DLC-1 was about -25 mV, and the zeta potential in DLC-2 was -50 mV or less. Thus, in the carbonaceous film having a carbon-oxygen bond, the zeta potential shows a negative value, and since the DLC-2 having a high ratio of O═C—O shows a particularly low value, It is considered that a carboxyl group is formed on the surface of the film.

  FIG. 10 shows the results of running tests on the aqueous gel ink having the same composition as the measurement of the contact angle described above. The ball pen refill ball of a commercially available water-based gel ink ballpoint pen (manufactured by Pilot Corporation: G-2) was replaced with a ball on which DLC-1 or DLC-2 was formed. The ink containing cylinder was filled with an aqueous gel ink having the same composition as that used for measuring the contact angle. The diameter of the ball is 0.7 mm, and the average value measured for 10 ballpoint pens is shown. The load applied to the ballpoint pen was 100 gf (about 0.98 N). In addition, as a control, the same applies to a ballpoint pen mounted with a ball on which a DLC film (DLC-0) without active functional group introduction and a ballpoint pen with an untreated ball not formed with a DLC film are mounted. Measurements were made.

  In the case of an untreated ball with no carbonaceous film formed, the amount of wear increased as the writing distance increased, and at a writing distance of 1000 m, wear of 0.01 mm or more was observed. In addition, in the case of conventional DLC (DLC-0) which does not actively introduce functional groups on the surface, the wear amount was stabilized at about 0.001 mm in the first half of the test, but when the writing distance became 600 m or more. An increase in the amount of wear was observed. On the other hand, in the case of DLC-1, almost no wear was observed up to a writing distance of 800 m, and only about 0.001 mm of wear was observed even at 1000 m. In the case of DLC-2, no wear was observed. In general, it is considered that the ball seat in the ball holder is most easily worn, and the increase in the wear amount (sink amount) is due to the wear of the ball seat. In water-based gel inks, mixed lubrication between the ball and the ball seat is considered, but in the case of DLC-1 and DLC-2, the affinity between the ball and the water-based gel ink is improved. This is considered to be because the ink and the ball seat are not easily worn and the ball and the ball seat are less likely to wear. Moreover, in DLC-2 with higher affinity with water-based gel ink, it is thought that the amount of wear was further reduced.

  FIG. 11 shows the results of a running test when the ball diameter is 0.5 mm. In this case, the binder of the WC ball is changed from cobalt (Co) to nickel (Ni). The ball diameter is 0.5 mm, and the average value measured for 10 ballpoint pens prepared in the same manner as in the case where the ball diameter is 0.7 mm is shown. The load applied to the ballpoint pen was 100 gf (about 0.98 N). As in the case of the ball diameter of 0.7 mm, the amount of wear increased as the writing distance increased. When the writing distance was 900 m, wear of about 0.01 mm occurred. In addition, in the case of the conventional DLC (DLC-0) in which the functional group is not actively introduced on the surface, no wear was observed in the first half of the test, but an increase in wear was recognized from a writing distance of 700 m. . On the other hand, in the case of DLC-1, the writing distance was not worn up to 500 m, and even at 1000 m, the wear amount was 0.001 mm or less. In the case of DLC-2, almost no wear was observed even at a writing distance of 1000 m. As in the case where the ball diameter is 0.7 mm, the affinity between the ball and the ink is improved, the ink is sufficiently held between the ball and the ball seat, and the direct contact between the ball and the ball seat is prevented. This is probably because the ball and the ball seat are less likely to wear. Moreover, in DLC-2 with higher affinity with water-based gel ink, it is thought that the amount of wear is further reduced.

  FIG. 12 shows the results of running tests on oil-based ink having the same composition as that used for measuring the contact angle. The ball diameter is 0.5 mm, and an average value obtained by measuring 10 ballpoint pens prepared in the same manner as in the case of the water-based gel ink is shown. The ink containing cylinder was filled with an oily gel ink having the same composition as that used for measuring the contact angle. In the oil ballpoint pen, since the writing pressure becomes high, the load applied to the ballpoint pen was set to 400 gf (about 3.92 N). In the case of a ball not formed with a carbonaceous film, the amount of wear increases as the writing distance increases as in the case of the water-based gel ink. When the writing distance is 1000 m, wear of about 0.01 mm occurs and 1500 m Then, wear of about 0.02 mm occurred. In addition, in the case of the conventional DLC (DLC-0) which does not actively introduce functional groups on the surface, no wear was observed in the first half of the test, but an increase in wear was observed from a writing distance of 900 m. It was. On the other hand, in the case of DLC-1 and DLC-2, almost no wear was observed at a writing distance of 1500 m. In general, oil-based ink is considered to be fluid lubrication between a ball and a ball seat, but is mixed lubrication because of its low viscosity. In the case of DLC-1 and DLC-2, the affinity between the ball and the oil-based ink is improved, the ink is sufficiently held between the ball and the ball seat, and the direct contact between the ball and the ball seat occurs. This is probably because the ball and the ball seat are less likely to wear. Thus, the durability was greatly improved not only in the aqueous gel ink but also in the oil-based ink. In the case of oil-based ink, the amount of wear of the ball seat is larger than that of water-based gel ink because of the load applied to the ballpoint pen.

  FIG. 13 shows the results of running tests on water-based ink having the same composition as that used for contact angle measurement. The ball diameter is 0.5 mm, and an average value obtained by measuring 10 ballpoint pens prepared in the same manner as in the case of the water-based gel ink is shown. The ink containing cylinder was filled with water-based ink having the same composition as that used for measuring the contact angle. The load applied to the ballpoint pen was 100 gf (about 0.98 N). Even in the case of the water-based ink, when the carbonaceous film was not formed, the wear amount increased as the writing distance increased, and when the writing distance was 1000 m, the wear was about 0.01 mm. In addition, in the case of conventional DLC (DLC-0) which does not actively introduce functional groups on the surface, no wear is recognized in the first half of the test, but the writing distance is recognized from 200 m, and from 600 m. Increased wear was observed. On the other hand, in the case of DLC-1, the wear at a writing distance of 600 m was about 0.001 mm, and at 1000 m, it was about 0.002 mm. In the case of DLC-2, almost no wear was observed even at a writing distance of 1000 m. Even in water-based ink, it is considered that the mixed lubrication between the ball and the ball seat is, but when the carbonaceous film having a carbon-oxygen bond is formed, the affinity between the ball and the water-based ink is improved. It is considered that the direct contact between the ball and the ball seat is less likely to occur, so that the ball and the ball seat are less likely to be worn.

If a carbonaceous film is formed not only on the surface of the ball but also on the surface of the ballpoint pen tip, the wear resistance is further improved. In this case, a carbonaceous film may be formed so as to cover at least a portion of the ball holder that contacts the ball. The carbonaceous film formed on the surface of the ballpoint pen tip may be the same as or different from the carbonaceous film formed on the surface of the ball in terms of the amount of functional groups introduced or the value of CO _total . Further, when a carbonaceous film is formed on the surface of the ballpoint pen tip, an intermediate layer may be formed between the carbonaceous film and the ballpoint pen tip.

  For example, a carbonaceous film having the same composition as DLC-1 is formed on the surface of the ballpoint pen tip in the same manner as the running test in the case of the oil-based ink shown in FIG. 12, and DLC-1 or DLC-2 is formed on the ballpoint pen tip. A running test was conducted on ten ballpoint pens equipped with the formed balls. In this case, almost no wear was observed at a writing distance of 1000 m in both the ball formed with DLC-1 and the ball formed with DLC-2. Also, even when a carbonaceous film having the same composition as DLC-2 is formed on the surface of the ballpoint pen tip, both the ball formed with DLC-1 and the ball formed with DLC-2 are almost at a writing distance of 1000 m. No wear was observed.

  When a carbonaceous film is formed on the ball holder, it is possible to use a ball not covered with the carbonaceous film. FIG. 14 shows the results of a running test when the ball is a normal ball not covered with a carbonaceous film and the carbonaceous film is formed on the surface of the ballpoint pen tip. As shown in FIG. 6, conventional DLC (DLC-0), DLC-1 and DLC-2 ball holders are formed so as to cover the front edge 118, bottom surface 116, ball seat 117, and the like of the ball holder 111. Formed. The ball was a WC ball having a diameter of 0.5 mm with a normal cobalt binder. The average value measured about ten ball-point pen refills which filled oil ink of the same composition as what was used for the measurement of a contact angle in an ink storage cylinder is shown. The load applied to the ballpoint pen was 400 gf (about 3.92 N).

  As shown in FIG. 14, when DLC-1 or DLC-2 is formed on the ball holder side, the writing distance of 1000 m is almost the same as when DLC-1 or DLC-2 is formed on the ball side. No wear was observed. On the other hand, when the untreated ball holder or the conventional DLC-0 was formed, wear of about 0.01 mm to 0.005 mm occurred as the writing distance increased.

  In the results of the running tests shown in FIGS. 10 to 13, it was recognized that slight wear occurred even when DLC-1 or DLC-2 was formed. The inventors of the present application have found that the slight wear that occurs when DLC-1 or DLC-2 is formed is affected by the surface roughness of the ball body before the carbonaceous film is formed.

  FIG. 15 shows the results of running tests on water-based gel inks with DLC-1 formed on the surface of WC balls having different arithmetic average roughnesses (Ra). In the results of the running test, ◎ indicates that no wear was observed at all, and ◯ indicates that slight wear of about 0.003 mm was observed. When DLC-1 was formed on a ball body having an Ra of less than 3 nm, no wear was observed even at a writing distance of 1000 m. On the other hand, when DLC-1 was formed on a ball body having a Ra of 3 nm or more, wear of about 0.003 mm was observed at a writing distance of 1000 m. As shown in FIG. 16, the same result as in the case of 0.5 mm was obtained when the diameter of the ball body was 0.7 mm. Further, as shown in FIGS. 17 and 18, similar results were obtained in the case of oil-based ink. Since the results of the running test are not significantly different between the water-based ink and the water-based gel ink, it is considered that the same result can be obtained with the water-based ink. Also, in the case of DLC-2, it is considered that the same result can be obtained although the difference in the amount of wear is small. Thus, the amount of wear can be further reduced by setting the Ra of the ball body forming the DLC film having the functional group introduced therein to less than 3 nm. The ball body used was a commercially available WC ball (manufactured by Tsubaki Nakashima Co., Ltd.), and the value of Ra used was the value attached to the product. The same effect can be obtained not only when the ball body is a WC ball but also when it is made of other ceramics or stainless steel.

  The ballpoint pen tip and the ballpoint pen according to the present invention are useful as a ballpoint pen tip and a ballpoint pen because the ball and the ball holder are less likely to wear and show good writing characteristics over a long period of time.

DESCRIPTION OF SYMBOLS 10 Ink receiving tube 15 Ink 20 Ball-point pen tip 101 Ball 102 Ball main body 103 Carbonaceous film 111 Ball holder 113 Ball holding chamber 114 Ink passage 115 Groove part 116 Bottom face 117 Ball seat 118 Tip edge part 121 Carbonaceous film

Claims (11)

A ball having a ball body and a carbonaceous film covering a surface of the ball body;
A ball holder for rotatably holding the ball;
The carbonaceous film has a carbon atom and an oxygen atom bonded to the carbon atom,
The ratio of carbon atoms bonded to oxygen atoms on the surface of the carbonaceous film to all carbon atoms is 0.1 or more.   The ballpoint pen tip according to claim 1, wherein the carbonaceous film has a zeta potential of -25 mV or less on the surface thereof. ^3. The ballpoint pen tip according to claim 1, wherein the carbonaceous film has a ratio of sp ³ carbon-carbon bond to sp ² carbon-carbon bond of 0.3 or more. The ball has an intermediate layer formed between the ball body and the carbonaceous film,
The ballpoint pen tip according to claim 1, wherein the intermediate layer includes carbon and silicon.   The ballpoint pen tip according to any one of claims 1 to 4, wherein the arithmetic mean roughness on the surface of the ball body is 3 nm or less.   The ballpoint pen tip according to claim 1, wherein the ball holder has a carbonaceous film covering at least a portion in contact with the ball. With the ball,
A ball holder for rotatably holding the ball;
The ball holder has a carbonaceous film covering at least a portion in contact with the ball,
The carbonaceous film has a carbon atom and an oxygen atom bonded to the carbon atom,
The ratio of carbon atoms bonded to oxygen atoms on the surface of the carbonaceous film to all carbon atoms is 0.1 or more.   The ballpoint pen tip according to claim 7, wherein the carbonaceous film has a zeta potential of −25 mV or less on a surface thereof. 9. The ballpoint pen tip according to claim 7, wherein the carbonaceous film has a ratio of sp ³ carbon-carbon bond to sp ² carbon-carbon bond of 0.3 or more. The carbonaceous film is formed on the surface of the ball holder via an intermediate layer,
The said intermediate | middle layer contains carbon and a silicon | silicone, The ball-point pen tip of any one of Claims 7-9 characterized by the above-mentioned. The ballpoint pen tip according to any one of claims 1 to 10,
An ink containing tube filled with ink,
The contact point of the ink on the surface of the carbonaceous film is 55 ° or less.

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