JP2006307157A - Electrodeposition coating material, electrodeposition coated film, sliding member and card reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly general-purpose electrodeposition coating material having not only heat resistance/discharge performance, but also sliding properties. <P>SOLUTION: The electrodeposition coating material for an electrodeposition coated film is obtained by using a heat-resistant resin material as a base material, and adding a solid lubricating agent and an electroconductive inorganic filler. The pH of an electrodeposition liquid containing the dispersing elements of the electrodeposition coating material is kept within the span of control of pH 3-4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrodeposition coating material, an electrodeposition coating film, a sliding member, and a card reader that are used when a coating object is coated by electrodeposition coating.

  Conventionally, from the viewpoints of appearance, rust prevention, insulation, etc., for example, an organic coating film is generally formed on a component of a card reader as an electronic device. With higher precision, the demand for thinner organic coatings is increasing.

  Electrodeposition coating is a technique for forming an organic coating film. In this method, an electrodeposition resin material is deposited on the surface of an electrodeposition coating object (work) by an electrophoretic reaction, and a coating film is formed by drying and curing in post-processing. It can be said that this is a technique that can be easily made into a thin film. In addition, this electrodeposition coating not only facilitates thinning of the film, but also eliminates the need for dimensioning by secondary processing, does not waste paint, enhances the adhesion to the substrate, Various benefits such as good uniformity can be obtained.

  For these reasons, in recent years, electrodeposition coating having many advantages has been attracting attention as a method for forming an organic coating film (see, for example, Patent Document 1).

JP-A-11-108050 (paragraph number [0054])

  However, conventional electrodeposition coating materials use resin materials such as acrylic-melamine-based materials, epoxy-melamine-based materials, alkyd-melamine-based materials, and acrylic-urethane-based materials as their base materials.・ Sliding (wear resistance) was lacking. That is, when a mating member such as resin, metal, or ceramic is slid on the surface on which an organic coating film (: electrodeposition coating film) is formed by electrodeposition coating, frictional heat of about 150 degrees or more is generated, and the temperature exceeds a certain temperature. Under these conditions, the seizure phenomenon may be increased.

  In addition, the organic coating film (electrodeposition coating film) formed by electrodeposition coating has low electrical conductivity, and the electric charge charged by sliding of the contact member does not readily discharge, so the upper part of the part that has been subjected to electrodeposition coating. There is a risk of adversely affecting the device.

  As described above, the conventional electrodeposition coating materials are often used for limited applications that do not require slidability and discharge properties, and their greatest disadvantage is that they are not versatile.

  The present invention has been made in view of these points, and its purpose is not only to have heat resistance and discharge properties, but also to have sliding properties, so that it is highly versatile electrodeposition coating. To provide materials.

  In order to solve the above problems, the present invention adds a solid lubricant and a conductive inorganic filler to a heat-resistant resin material in order to ensure its heat resistance, slidability, and discharge performance. Furthermore, the pH of the electrodeposition liquid containing the dispersion of the electrodeposition coating material is controlled.

  More specifically, the present invention provides the following.

  The present invention is an electrodeposition coating material of an electrodeposition coating film comprising a heat-resistant resin material as a base material and containing a solid lubricant and a conductive inorganic filler, and includes a dispersion of the electrodeposition coating material The pH of the electrodeposition liquid is maintained within a control range of pH 3-4.

  According to this invention, the electrodeposition coating material is obtained by adding a solid lubricant and a conductive inorganic filler to a base material made of a heat-resistant resin material. Since the electrodeposition liquid is electrodeposited while maintaining the pH within the control range of pH 3 to 4, the coating amount of the solid lubricant can be limited, and not only heat resistance and discharge properties but also excellent sliding properties It will be something that combines.

That is, in the prior art, the electrodeposition coating material having heat resistance does not have sufficient slidability with respect to a specific member (resin, metal, ceramic, etc.), so that the objects frequently come into contact with each other. Although it was not suitable for painting on a sliding part, according to the present invention, since it has both heat resistance and sliding property, it is suitable for painting on such a part. In particular, in order to limit the coating amount of the solid lubricant that affects the slidability, the pH of the electrodeposition liquid containing the dispersion of the electrodeposition coating material is maintained within the control range of 3 to 4. It is only necessary to manage it, and excellent slidability can be ensured.
In addition, conventionally, physical processing is performed on the components of the electronic device (for example, the insulating portion is cut), and the charge that is charged due to sliding with the contact member is released. Accordingly, the electrical conductivity can be increased by the action of the conductive inorganic filler, so that such a complicated processing operation becomes unnecessary, and as a result, it is possible to contribute to the improvement of the versatility of the electrodeposition coating material. .

  Therefore, the application of the electrodeposition coating material can be expanded, and as a result, the versatility of the electrodeposition coating material can be enhanced.

  Examples of the solid lubricant include those having a layered molecular structure with a relatively long interlayer distance, such as polytetrafluoroethylene, molybdenum disulfide, tungsten disulfide, and graphite.

  Some conductive inorganic fillers have not only electrical conductivity but also self-lubricating properties and wear resistance, and can further improve the slidability of the above-mentioned electrodeposition coating material.

  In the present invention, it is preferable that polyimide is used as the heat resistant resin material, polytetrafluoroethylene is used as the solid lubricant, and graphite is used as the solid lubricant and the conductive inorganic filler.

According to this invention, in the electrodeposition coating material described above, polytetrafluoroethylene as a solid lubricant is added to polyimide as a heat-resistant resin material, and graphite is added as a solid lubricant and a conductive inorganic filler. Therefore, it not only has heat resistance but also has slidability and electric discharge, which can contribute to the improvement of versatility of the electrodeposition coating material. In particular, since solid lubricants are expensive, it is necessary to increase the efficiency of use.However, since solid lubricants generally precipitate without being dispersed in the base resin, they are not suitable for electrodeposition coating. Tetrafluoroethylene has good coating efficiency by electrodeposition coating,
Cost reduction is possible.

  Here, the “polyimide” in the present invention may have an alicyclic portion on either the acid side or the amine side constituting the polyimide. Of course, you may have an alicyclic part in both the acid side and the amine side.

  In addition, since graphite is comparatively cheap, it can also contribute to the manufacturing cost reduction of the components in which the electrodeposition coating material is used.

  Further, the present invention includes 10 to 20% by weight of the polyimide, the polytetrafluoroethylene includes a weight ratio of 20 ± 5% by weight of the polyimide, and the graphite has a weight ratio of 2 to 5% of the polyimide. % Is preferable.

  According to this invention, the above-mentioned electrodeposition coating material is composed of 10 to 20% by weight of polyimide, 20 ± 5% by weight of polytetrafluoroethylene in terms of solid content of polyimide, and 2 to 5% in weight of graphite by weight of polyimide. Since it contains by weight, not only has heat resistance, but also has slidability and discharge properties, which in turn can contribute to improving the versatility of the electrodeposition coating material.

  In this case, when the content of the polyimide as the heat resistant resin material is less than 10% by weight, the polytetrafluoroethylene as the solid lubricant tends to precipitate during the electrodeposition coating of the electrodeposition coating object. This is not preferable, and if the polyimide content is more than 20% by weight, the surface energy tends to be low, and the appearance of coating such as repellency tends to be poor.

  Further, if the content of polytetrafluoroethylene as a solid lubricant is less than 20-5% by weight, it is not preferable because the lubricity tends to be insufficient, and the content of polytetrafluoroethylene is not preferable. If the amount is more than 20 + 5% by weight, for example, the conductive inorganic filler added for adding discharge property tends to settle in the electrodeposition coating tank without being uniformly dispersed in the electrodeposition coating solution.

  Furthermore, if the content of graphite as the conductive inorganic filler is less than 2% by weight, the discharge property tends to be insufficient, and it is not preferable, and if the content of graphite is more than 5% by weight. Since graphite tends to precipitate during the electrodeposition coating of the object to be electrodeposited, it is not preferable.

  Further, according to the present invention, the amount of polytetrafluoroethylene deposited is 4% to 25 in terms of the weight ratio of fluorine to carbon on the surface of the coating film, as determined by semi-quantitative elemental analysis of the electrodeposition coating film using a scanning electron microscope. % Is preferred.

  According to the present invention, the amount of polytetrafluoroethylene deposited on the above-mentioned electrodeposition coating film is in the range of 4% to 25% by weight ratio of fluorine and carbon on the surface of the coating film. Function can be improved. As a result, it can contribute to improving the versatility of the electrodeposition coating material.

  In this case, if the amount of polytetrafluoroethylene deposited exceeds a range of 4% to 25%, the electrodeposition coating film may peel off. In particular, in the case where the coating film surface is slid, the sliding resistance is different at the place where peeling occurs, and therefore slip and chatter phenomenon occur, which is not preferable.

  In addition, the semi-quantitative analysis of elements by a scanning electron microscope here is a typical analysis technique using a SEM semi-quantitative value (fluorine: F) method using a scanning electron microscope (SEM). Any analysis means may be used as long as it can perform qualitative and quantitative analysis of elements.

  In the present invention, the amount of polytetrafluoroethylene deposited on the surface of the electrodeposition coating film is equal to or greater than the amount of polytetrafluoroethylene deposited in the electrodeposition coating film. It is preferable to contain.

  According to this invention, since the surface of the electrodeposition coating film contains a large amount of polytetrafluoroethylene, it is possible to further improve the slidability function. As a result, it can contribute to improving the versatility of the electrodeposition coating material.

  Moreover, it is preferable that this invention is a sliding member provided with the sliding part in which the electrodeposition coating film was formed with the said electrodeposition coating material.

  According to the present invention, the sliding member on which the contact member (for example, IC card) slides is configured to include the sliding portion in which the electrodeposition coating film is formed by the above-described electrodeposition coating material. The sliding member has heat resistance, slidability, and discharge property, and its application can be expanded.

  Furthermore, it is preferable that this invention is a card reader which comprised the card | curd travel reference surface using the said sliding member.

  According to this invention, since the card reader uses the sliding member described above to constitute the card travel reference surface, it is possible to prevent wear deterioration of the inserted card and the inserted card is a card. Charges that are charged due to sliding with the running reference surface can be released.

  According to this invention, the electrodeposition coating material is obtained by adding a solid lubricant and a conductive inorganic filler to a base material made of a heat-resistant resin material. Since the pH of the electrodeposition liquid is maintained within the control range of pH 3 to 4, the coating amount of the solid lubricant can be limited, and it has not only heat resistance and discharge properties but also excellent sliding properties. it can.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

[Method of synthesizing electrodeposition coating materials]
First, an example of a method for synthesizing an electrodeposition coating material according to an embodiment of the present invention will be described. The method for synthesizing the electrodeposition coating material is not limited to the following method.

  The heat-resistant resin material that is the base of the electrodeposition coating material according to the embodiment of the present invention is polyimide, and this polyimide is an acid component (for example, bicyclooct-7-ene-2, 3, 5,6-tetracarboxylic dianhydride, etc.) are dissolved in a solvent (eg, N-methylpyrrolidone, etc.), the solution is stirred for several hours, and the resulting solution is placed in a dialysis tube. It is synthesized by removing miscellaneous ions such as organic solvents. The polyimide synthesized in this embodiment is a cationic one that is positively charged, but the present invention is not limited to this, and may be an anionic one that is negatively charged. . Moreover, the dialysis performed using a dialysis tube is performed until the solution becomes almost neutral. Note that this adjustment example is an example, and the present invention is not limited to this.

  Next, polytetrafluoroethylene is added as a solid lubricating material for improving lubricity at a polyimide solid content weight ratio of 5 to 40% by weight to 10 to 20% by weight of the polyimide obtained through the above-described steps. Here, it is preferable to add polytetrafluoroethylene at a polyimide solid content weight ratio of 10 to 30% by weight (particularly 20 ± 5% by weight). Polytetrafluoroethylene having a particle diameter of 0.2 μm to 5.0 μm was used. As a result, the solution can be prevented from becoming a gel (semi-solid) or precipitation can be prevented, and the management of the electrodeposition solution (solution) is facilitated. In the present embodiment, polytetrafluoroethylene is added as a solid lubricating material. However, the present invention is not limited to this, and inorganic fillers such as carbon-based molybdenum disulfide (MoS2) such as graphite, CNF, and carbon black. May be added.

  Next, conductive inorganic fillers such as graphite, carbon black, and metal particles are added at a solid content weight ratio of 3 to 15% by weight to the solution containing the solid lubricant obtained through the above steps. . Here, considering the combined addition with polytetrafluoroethylene, it is preferable to add a conductive inorganic filler at a solid content weight ratio of 3 to 5% by weight of the polyimide. Thereby, it is possible to obtain an electrodeposition coating material that has both lubricity and electric resistance (discharge property) and is optimal for the management of the electrodeposition liquid.

  In addition, in order to make the electrodeposition coating material obtained by obtaining the above-mentioned process water-soluble, a solvent such as ion-exchanged water, weak acid such as lactic acid / acetic acid, or IPA / butyl cellosolve may be added.

[Electrodeposition conditions]
Next, an example of the conditions for the electrodeposition liquid according to the embodiment of the present invention will be described. The conditions for the electrodeposition liquid are not limited to the following.
The electrodeposition liquid in which the electrodeposition coating material is dispersed (immersed) gradually deviates from the pH value during the bathing after the start of the electrophoresis reaction. Therefore, after the start of the reaction, the pH is controlled within a range of 3 to 4 by, for example, replenishment of the electrodeposition solution, substitution, ion exchange, or acid addition.

[Electrodeposition coating]
FIG. 1 is a process explanatory view for schematically explaining a process of an electrodeposition coating film forming method using an electrodeposition coating material according to an embodiment of the present invention.

In FIG. 1, the electrodeposition coating material according to the embodiment of the present invention is mixed with ion-exchanged water, and the pH is adjusted as appropriate by acid addition or the like. The object to be coated (work) 2 is immersed.
In such a state, the electrodeposition coating object 2 set in the electrolytic cell 3 is a cathode, the electrode 20 serving as a counter electrode is an anode, a DC power source 4 is connected between them, and a DC voltage is applied ( FIG. 1 (a)). Note that the temperature, current density, and the like of the electrodeposition liquid 1 at this time are set to optimum conditions depending on the type of the electrodeposition coating object 2. For example, in the embodiment of the present invention, the applied voltage is 10 to 300 V, the soft start is 10 to 120 seconds, the electrodeposition time is 60 to 180 seconds, and constant voltage control (constant current control) can be performed.

  Next, when a certain period of time elapses in the step of FIG. 1A, a chemical reaction proceeds in the electrodeposition liquid 1, and the pH value increases and becomes an alkali side. As described above, the pH is controlled within the range of 3 to 4 by replenishing and replacing the electrodeposition solution, ion exchange, acid addition or the like. According to this pH control, the conductivity is 450 μs / cm to 550 μs / cm. In this state, the electrodeposition liquid 1 around the electrodeposition object 2 that is a cathode is gradually condensed to form an insoluble resin (polymer) to form an electrodeposition coating film 5 (FIG. 1B). . In addition, on the said conditions, a film thickness can be about 5-25 micrometers.

In addition, the coating amount of polytetrafluoroethylene on the surface of the electrodeposition coating film (several μm in the depth direction) is determined by the SEM semi-quantitative value ( fluorine) method using a scanning electron microscope. The weight ratio with carbon can be in the range of 4 wt% to 25 wt%.

Finally, after the electrodeposition coating film 5 is formed on the electrodeposition coating object 2 in the step of FIG. 1B in the electrodeposition coating process as described above, in this embodiment, the electrodeposition coating object 2 The electrodeposition coating film 5 is cured and electrodeposited by sequentially performing a heat curing process for about 40 minutes at a temperature of about 230 degrees after passing through a drying process at about 110 ° C. for about 15 minutes. The coating film 5 is formed to complete the formation of the electrodeposition coating film (FIG. 1C).
The processing conditions (temperature / time) here are predetermined processing conditions and are not limited. In addition, as shown in FIG.1 (c), it is not necessary to cover all the circumference | surroundings of the electrodeposition coating object 2 with the electrodeposition coating film 5, and you may coat only one part. By providing such a non-film forming part (non-coating part), it is possible to provide the electrodeposition coating object 2 with a ground for releasing the staying charge.

Further, when it is desired to further add polytetrafluoroethylene, it is possible to add an immersion treatment step in the polytetrafluoroethylene dispersion during the electrodeposition coating film forming step. In the immersion treatment process, polytetrafluoroethylene is further imparted to the electrodeposition coating film 5 by immersing in the polytetrafluoroethylene dispersion either after the electrodeposition coating process, after the drying process, or after the thermosetting treatment. can do. Specifically, in this embodiment, after the electrodeposition coating step, the electrodeposition coating film 5 is further immersed in the polytetrafluoroethylene dispersion 80 at room temperature to further adhere polytetrafluoroethylene to the electrodeposition coating film 5. can do. The polytetrafluoroethylene dispersion 80 is preferably agitated during the immersion treatment step, but is not limited thereto. Further, the temperature of the polytetrafluoroethylene dispersion 80 can be changed as appropriate. Moreover, in the immersion treatment step, it is not necessary to immerse the entire periphery of the electrodeposition coating film 5 in the polytetrafluoroethylene dispersion 80, and only a part may be immersed.
In particular, the electrodeposition coating 5 is in a state where voids are formed in the resin as the base material before the thermosetting treatment step, and the polytetrafluoroethylene in the polytetrafluoroethylene dispersion 80 is the electrodeposition coating. 5 is easy to immerse.
Polytetrafluoroethylene having a particle diameter of 0.2 μm to 5.0 μm was used. The immersion time was about 1 minute, and the concentration of polytetrafluoroethylene was determined as follows.
In the dipping process, the apparatus uses a tank for storing the polytetrafluoroethylene dispersion 80 and, if necessary, a known one such as agitation, so the explanation in the figure here is Omitted.

FIG. 2 is a graph showing the correlation between the amount of polytetrafluoroethylene deposited on the electrodeposition coating film 5 quantified by the SEM method and the concentration of the polytetrafluoroethylene dispersion, and the horizontal axis represents the polytetrafluoroethylene in the dispersion. The solid content concentration is shown, and the vertical axis shows the semi-quantitative fluorine value (% by weight) for quantifying the content value of polytetrafluoroethylene.
FIG. 2 (a) is a graph showing the result of immersion in the polytetrafluoroethylene dispersion after the electrodeposition coating process, and FIG. 2 (b) is the result of immersion in the polytetrafluoroethylene dispersion after the drying process. It is a graph which shows. In any graph, the fluorine quantitative value (indicated by a diamond symbol) on the surface of the electrodeposition coating film 5 (hereinafter referred to as electrodeposition coating material 2) formed on the electrodeposition coating material 2, and the internal Fluorine quantitative values (indicated by square symbols) are measured.
Here, the “surface” is based on the detection range of the scanning electron microscope used in this example, and refers to a thickness of about 0.2 μm to 0.25 μm from the surface of the electrodeposition coating film 5. . On the other hand, “inside” indicates a coating portion deeper than this “surface”.
The polytetrafluoroethylene dispersion may be any one as long as it contains polytetrafluoroethylene, and a commercially available one can be used.

  As shown in FIG. 2 (a), the concentration of the polytetrafluoroethylene dispersion to be immersed after the electrodeposition coating process is also determined from the degree of saturation of the amount of polytetrafluoroethylene on the surface of the electrodeposited coating 2 and inside. It can be seen that the partial concentration may be 0.5 to 20% by weight, preferably about 4%. Further, as shown in FIG. 2 (b), the concentration of the polytetrafluoroethylene dispersion to be immersed after the drying step is increased from about 0.5%, and the surface of the electrodeposition coated article 2 and the inside thereof are increased by about 4%. Since the amount of polytetrafluoroethylene in this sample is almost saturated and reaches 20% saturation, it is understood that the solid content concentration may be 0.5 to 20% by weight, preferably about 4%.

  Further, in FIG. 2A, the semi-quantitative value of fluorine only when the electrodeposition coating process is performed under the above predetermined conditions is shown as a polytetrafluoroethylene dispersion solid content concentration of 0%. On the other hand, when the immersion treatment is performed in the polytetrafluoroethylene dispersion liquid after the electrodeposition coating process, that is, when the immersion process is performed, the concentration of the polytetrafluoroethylene dispersion liquid is 4%. The number of polytetrafluoroethylenes in the interior is increased by several percent.

  Similarly, in FIG. 2B, the fluorine semi-quantitative value only when the electrodeposition coating process is performed under the above-mentioned predetermined conditions is shown as a polytetrafluoroethylene dispersion solid content concentration of 0%. On the other hand, when the immersion process is performed in the polytetrafluoroethylene dispersion after the drying process, that is, when the immersion process is performed, the surface of the electrodeposition-coated article 2 and the concentration of the polytetrafluoroethylene dispersion are 4%, and The amount of internal polytetrafluoroethylene is increased by 2% to 3%, respectively.

  Thus, in the case where the immersion treatment process is performed after the electrodeposition coating process shown in FIG. 2A, and also in the case where the immersion treatment process is performed after the drying process shown in FIG. The polytetrafluoroethylene content on the surface of the electrodeposition coated product 2 is increased with respect to the polytetrafluoroethylene content inside the coated product 2. Therefore, polytetrafluoroethylene is more adhered to the surface of the electrodeposition coated article 2 by the dipping process.

  Further, in any case, the polytetrafluoroethylene content in the electrodeposited product 2 that has only undergone the electrodeposition coating process (the value of 0% in FIG. 2 (a) and FIG. 2 (b)) However, the polytetrafluoroethylene content on the surface of the electrodeposited article 2 is higher than the polytetrafluoroethylene content inside the electrodeposited article 2.

  Therefore, when the electrodeposition coating film is formed using this electrodeposition material, the polytetrafluoroethylene content on the surface of the electrodeposition coating material 2 is compared with the polytetrafluoroethylene content in the electrodeposition coating material 2. In addition to the higher content, the polytetrafluoroethylene content on the surface of the electrodeposition coated product 2 can be further increased when an immersion treatment process is performed.

  Therefore, when an electrodeposition coating film is formed on the sliding surface of the card reader listed below as an example of the use of the electrodeposition coating material in this process, only when the electrodeposition coating process is performed (without the immersion treatment process) Even when the immersion treatment process is performed as appropriate, a larger amount of polytetrafluoroethylene is contained on the sliding surface side, so that an electrodeposition coating film with further excellent slidability is formed. It becomes.

  Also, when immersed in a polytetrafluoroethylene dispersion after the electrodeposition coating step → drying step → thermosetting treatment step, that is, when the concentration of the polytetrafluoroethylene dispersion is increased even after the immersion treatment step. The content of polytetrafluoroethylene in the surface of the electrodeposition coated article 2 and the inside thereof is increasing (not shown).

  Furthermore, after the electrodeposition coating process, it may be subjected to an immersion treatment process in a polytetrafluoroethylene dispersion liquid having a predetermined concentration, and may further be subjected to an immersion treatment process in a polytetrafluoroethylene dispersion liquid having a predetermined concentration after the drying process, or You may pass through the immersion treatment process to the polytetrafluoroethylene dispersion liquid after the thermosetting treatment process after passing through the immersion treatment process to the polytetrafluoroethylene dispersion liquid of a predetermined density | concentration after a drying process. That is, any combination may be used that undergoes an immersion treatment step in the polytetrafluoroethylene dispersion after the above steps.

  The electrodeposition coating object 2 formed with the electrodeposition coating film 5 through the above-described steps has not only heat resistance but also slidability and discharge properties. It can be used as a sliding member having a sliding portion on which a mating member such as ceramic slides. Further, if the card running reference surface of the card reader is configured by using this sliding member, even if the card made of vinyl chloride is repeatedly slidably contacted with the electrodeposition coating film 5, the charge charged by static electricity can be released. As a result, it is possible to prevent malfunction of the card reader such as reading error or jitter failure. In addition, this electrodeposition coating film 5 is formed in the thickness of about 10 μm to 15 μm in the present embodiment.

[Examples of using electrodeposition coating materials]
FIG. 3 is a cross-sectional view showing the internal structure of the card reader 11 in the embodiment of the present invention. 3A is a horizontal sectional view in a direction parallel to the inserted vinyl chloride card 19, and FIG. 3B is a vertical sectional view in a direction parallel to the traveling direction of the card 19. FIG. FIG. 3C is a vertical sectional view in a direction perpendicular to the traveling direction of the card 19. In addition, although the use example of an electrodeposition coating material is demonstrated using a manual type card reader here, this invention is not limited to this, For example, this invention is applied to the roller conveyance type card reader using a motor. It is also possible.

  3 (a) to 3 (c), the manual card reader 11 is opposed to a frame 12 (see FIG. 3 (c)) having a substantially U-shaped cross section and a bottom 13 of the frame 12 sandwiched therebetween. Two side plate portions 14 and 15 (see FIG. 3B) and a magnetic head 17 (see FIG. 3B) projecting into the card passage 16 on at least one side of these side plate portions 14 and 15. is doing.

  A card travel reference plane S is formed on the bottom 13 of the U-shaped frame 12 (see FIGS. 3A and 3C). The bottom portion 13 on which the card travel reference surface S is formed corresponds to an example of the sliding portion described in the claims.

  Here, on the bottom portion 13, a coating film 18 (hatched portions in FIGS. 3A to 3C) made of the electrodeposition coating material according to the present invention is formed by the above-described electrodeposition coating. In the present embodiment, the bottom portion 13 is formed of resin integrally with the frame 12, but can also be formed by, for example, pressing a stainless steel plate. In that case, in order to securely fix the coating film 18 to the surface of the bottom portion 13 and to reduce sliding resistance between the card 19 and the bottom portion 13, the surface of the bottom portion 13 on which the coating film 18 is formed. The roughness is preferably as rough as possible. A coating film 18 made of the electrodeposition coating material according to the present invention is also formed on the opposing surfaces 14a and 15a of the two side plate portions 14 and 15 constituting the card passage 16 (the hatched portion in FIG. 3C). ). In addition, the coating film 18 uses what has not performed the immersion treatment process as shown in FIG.

  Thus, by forming the coating film 18 made of the electrodeposition coating material according to the present invention, which has both heat resistance and slidability, on the portion that is in sliding contact with the card 19, friction between the portion and the card 19 is achieved. It is possible to minimize heat generation due to the card, and to prevent card fatigue (wear). Further, as described above, the coating film 18 made of the electrodeposition coating material according to the present invention has a discharge property in addition to a heat resistance and a sliding property, and is charged due to the sliding with the contact member. This eliminates the need for complicated processing operations (for example, cutting the back surface of the frame 12) in order to escape the problem, which can contribute to improving the versatility of the electrodeposition coating material.

  4 and 5 are diagrams showing the results of an experiment performed using the card reader 11 according to the embodiment of the present invention. In this experiment, as in FIG. 3, the coating film used was not subjected to the immersion treatment step as shown in FIG. FIG. 4 (a) is a diagram showing the results of an accelerated pass test in which the card is moved faster than the normal speed. The horizontal axis shows the number of squeals due to friction, and the vertical axis shows the electrodeposition coating employed. Indicates the type of material. FIG. 4B is a diagram showing a card load amount (friction load amount) after the acceleration pass test of FIG. 4A, the horizontal axis shows the types of typical electrodeposition coating materials, and the vertical axis shows It shows the force (card load) required to pull out the inserted card. FIG. 3C is a diagram showing the relationship between the number of passes of the acceleration pass test of FIG. 4A and the charge amount of the electrodeposition coating material, and the horizontal axis is the pass of the acceleration pass test of FIG. The number of times is shown, and the vertical axis shows the charge amount of the electrodeposition coating material.

  FIG. 5 (a) is a diagram showing the correlation between the amount of polytetrafluoroethylene deposited on the electrodeposition coating film 5 determined by the SEM method and the pH of the electrodeposition liquid 1, and the horizontal axis shows the pH. The vertical axis represents the fluorine semi-quantitative value (% by weight). FIG. 5B is a diagram showing the correlation between the pH and the conductivity of the electrodeposition liquid, the horizontal axis indicates the pH, and the vertical axis indicates the conductivity (μS / cm).

According to FIG. 4 (a), when the current coating material based on epoxy resin is used (bottom), it begins to squeal twice on average about 30,000 passes, whereas polytetrafluoro It can be seen that when only ethylene (indicated by “PTFE” in the figure) is added at a polyimide solid content weight ratio of 30% by weight (second from the bottom), no squeal occurs even at an average of about 100,000 passes twice. . In other words, when polytetrafluoroethylene is added as a solid lubricating material, the number of times of squealing has increased by at least about 3 times (from 30,000 times to 100,000 times), improving slidability. I understand that. Although the maximum number of passes in FIG. 4A is 100,000, the accelerated pass test is performed only 100,000 times in this experiment. Therefore, the electrodeposition coating material when only polytetrafluoroethylene is added at a polyimide solid content weight ratio of 30% by weight can potentially withstand an accelerated pass test of 100,000 times or more.

Next, polytetrafluoroethylene is added at a polyimide solid content weight ratio of 20% by weight, and graphite (shown as “Gr” in FIG. 4) is added at a polyimide solid content weight ratio of 4% by weight (from the bottom). The third) shows that no noise is generated in the 100,000 pass test. In addition, when polytetrafluoroethylene is added at a polyimide solid content weight ratio of 10% by weight and graphite is added at a polyimide solid content weight ratio of 7% by weight (fourth from the bottom), an average of about 100,000 passes twice. You can see that it starts to sing. That is, even when graphite is added to improve the discharge performance, it is understood that the slidability is not lowered if the electrodeposition coating material is synthesized by the above distribution.

Next, when polytetrafluoroethylene is added at a polyimide solid content weight ratio of 5% by weight and graphite is added at a polyimide solid content weight ratio of 12% by weight (fifth from the top), approximately 20,000 passes. It begins to squeal and it can be seen that the slidability is significantly reduced. In addition, when molybdenum disulfide (indicated as “MoS ₂ ” in FIG. 4) instead of graphite is used as the conductive inorganic filler (third and fourth from the top), it begins to squeal at about 5000 passes. Also in this case, the slidability is significantly reduced.

  In DLC 1 μm, it starts to sound in about 35000 passes, and in the blank, it starts to sound in about 100,000 passes.

  Thus, according to FIG. 4 (a), in order to obtain a versatile electrodeposition coating material having both slidability and discharge property, polytetrafluoroethylene is used as the solid content weight ratio of polyimide. It can be seen that it is preferable to add 10 to 30% by weight (particularly 20 ± 5% by weight) and to add graphite at a polyimide solid content weight ratio of 2 to 5% by weight.

  Next, according to FIG. 4B, the card load of the current electrodeposition coating material is an average of about 120 g five times, whereas polytetrafluoroethylene is 20% by weight of the polyimide solid content, and It can be seen that when graphite is added at a polyimide solid content weight ratio of 4% by weight (right end), the average is about 60 g for 5 times. That is, when polytetrafluoroethylene is added as a solid lubricating material at a solid content weight ratio of 20% by weight, and graphite is added as a solid lubricating material and a conductive inorganic filler at a solid content weight ratio of 4% by weight, an insertion card is obtained. Since the force required when pulling out the wire is reduced by about half (from 120 g to 60 g), it can be seen that the slidability is improved.

  Thus, according to FIG. 4 (b), in order to obtain a versatile electrodeposition coating material having both slidability and dischargeability, polytetrafluoroethylene is used as the solid content weight ratio of polyimide. It can be seen that it is preferable to add 20% by weight and to add graphite at a polyimide solid content weight ratio of 4% by weight.

  Further, according to FIG. 4C, the change in charge amount with respect to the number of passes of the current electrodeposition coating material (black rhombus in the figure) shows the charge amount when the number of passes in the accelerated pass test is about 10,000. Is reduced from about 10 kV to about 3 kv, resulting in a discharge effect. On the other hand, when polytetrafluoroethylene is added at a polyimide solid content weight ratio of 30% by weight (black square in the figure), a discharge effect is produced even if the number of passes in the accelerated pass test exceeds 20,000. Absent.

Here, if graphite is added in order to prevent the discharge effect from being lowered due to the addition of polytetrafluoroethylene, the discharge effect is remarkably improved. That is, when polytetrafluoroethylene is added at a polyimide solid content weight ratio of 20% by weight and graphite is added at a polyimide solid content weight ratio of 4% by weight (black triangle in the figure), the pass of the acceleration pass test When the number of times is about 6000, the charge amount decreases from about 10 kV to about 5 kV, and a discharge effect is generated. Also, when polytetrafluoroethylene is added at a polyimide solid content weight ratio of 5% by weight and graphite is added at a polyimide solid content weight ratio of 7% by weight (indicated by a cross in the figure), the pass of the accelerated pass test When the number of times is about 6000, the charge amount decreases from about 10 kV to about 2 kV, and a discharge effect is generated.

  Thus, according to FIG. 4 (c), considering only the discharge performance, polytetrafluoroethylene was added at a polyimide solid content weight ratio of 5% by weight, and graphite was added at a polyimide solid content weight ratio of 7% by weight. However, considering the versatility and considering both slidability and discharge, polytetrafluoroethylene is added at a polyimide solid content weight ratio of 20% by weight, and graphite is added to the polyimide. It can be seen that the addition of 4 wt% of the solid content is optimal.

  On the other hand, according to FIG. 5 (a), when the pH of the electrodeposition liquid 1 was set to about 3.2 (left end), the fluorine semi-quantitative value was about 14% by weight on average for four times. On the other hand, when the pH was set to about 4.6 (right end), the fluorine semi-quantitative value was about 5% by weight on an average of 4 times. Further, when the pH of the solution 1 was set to about 4.3 (middle), the fluorine semi-quantitative value was about 6% by weight on an average of 4 times. As a result, as the pH was increased, the fluorine semi-quantitative value decreased and showed a negative correlation. That is, when the pH is set at 3 during the electrophoresis reaction and maintained as the electrodeposition condition, when the pH is set to 3, the polytetrafluoroethylene is compared with the case where the pH is set to about 4.5. The amount of precipitation is improved about 3 times. That is, when the pH is set to 3 to 4, the amount of polytetrafluoroethylene deposited can be in the range of 4% to 20% by weight, and the polytetrafluoroethylene in the electrodeposition coating adhered to the electrodeposition coating object When the amount of precipitation becomes an appropriate amount, slidability can be improved.

  Further, according to FIG. 5B, when the pH of the electrodeposition liquid 1 is set to about 3.2 (left end), the conductivity is 550 (μS / cm), and the pH is about 4.3. When set to, the conductivity was 450 (μS / cm). As a result, when the conductivity is in the range of 450 to 550 (μS / cm), the amount of polytetrafluoroethylene deposited can be in the range of 4 to 20% by weight as described above. When the amount of polytetrafluoroethylene deposited in the electrodeposition coating film adhering to the electrodeposition coating object becomes an appropriate amount, the slidability can be improved.

  Although not shown in the figure, when the pH is set to the extremely acidic side, a pinhole phenomenon occurs. Therefore, as described above, it is necessary to maintain the liquid management width at pH 3 to 4, during the electrophoresis reaction. It can be seen that pH control is important.

  FIG. 6 is a diagram showing a result of an experiment performed using the card reader 11 according to the embodiment of the present invention. Specifically, FIG. 8 is a comparative diagram showing the card static load (g) of the card reader 11 that has undergone the dipping process shown in FIG. 2 and the card static load (g) of the card reader 11 that is only in the electrodeposition coating process. It is. Here, the result when a load of 500 g is applied is shown. As a result, the static frictional force between the electrode coating film 18 formed on the opposing surfaces 14a and 15a of the two side plate portions 14 and 15 constituting the card passage 16 shown by the hatched portion in FIG. In comparison, the horizontal axis shows the electrodeposition coating process only (left side of the paper) and the electrodeposition coating process after immersion treatment (right side of the paper), and the vertical axis shows the static friction force of the card against the card (right side) Static load).

  According to FIG. 6, the static load of the electrodeposition coating film 18 only in the electrodeposition coating process is about 120 g on an average of five times, whereas the electrodeposition coating film 18 subjected to the immersion treatment after the electrodeposition coating process has a static load. It can be seen that the load is about 85 g on an average of 5 times. That is, since the static friction force is smaller after the immersion treatment step, the force required when pulling out the insertion card is reduced to about 2/3 (from 120 g to 85 g), so that the slidability is improved. I understand that.

  Thus, according to FIG. 6, it can be seen that it is preferable to go through an immersion treatment step in order to form the electrodeposition coating film 18 having good slidability.

[Modification]
In the above, the amount of polytetrafluoroethylene deposited was adjusted by controlling the pH conditions of the electrodeposition liquid 1, but after adjusting the pH, the applied voltage was further adjusted and the soft start was performed to further increase the amount of polytetrafluoroethylene. The amount of precipitation can be improved.

  FIG. 7 (a) is a diagram showing the correlation between the amount of polytetrafluoroethylene deposited determined by the SEM method and the applied voltage, the horizontal axis indicates voltage (V), and the vertical axis indicates the fluorine semi-quantitative value (weight). %). FIG. 7 (b) is a graph showing the correlation between the amount of polytetrafluoroethylene deposited determined by the SEM method and the soft start, the horizontal axis indicates the number of seconds of the soft start time, and the vertical axis indicates the semi-quantitative determination of fluorine. The value (% by weight) is shown.

  According to Fig.7 (a), when an applied voltage is set to 50V (left end), a fluorine semi-quantitative value is about 4 weight% on average 4 times. Further, when the applied voltage is set to 100 V (second from the left), the fluorine semi-quantitative value is about 7% by weight on average for four times, and when the applied voltage is further increased to about 180 V (right end) The fluorine semi-quantitative value was about 12% by weight on average over 4 times. As a result, as the applied voltage was increased, the fluorine semi-quantitative value increased, indicating a positive correlation. Although not shown, a positive correlation is obtained up to an applied voltage of 300V. Thus, the amount of polytetrafluoroethylene deposited can be controlled by increasing or decreasing the applied voltage. In other words, in addition to controlling the pH to 3-4, by simultaneously controlling the applied voltage, it can be in the range of 4 wt% to 20 wt%, and the electrodeposition coating film adhered to the electrodeposition coating object The slidability can be improved when the amount of polytetrafluoroethylene deposited therein becomes an appropriate amount.

  Further, according to FIG. 7B, when the soft start time is set to 20 seconds (middle), the fluorine semi-quantitative value is about 14% by weight, and the soft start time is set to about 40 seconds ( At the left end), the fluorine semi-quantitative value was about 9% by weight. Therefore, the amount of polytetrafluoroethylene deposited can be managed by increasing or decreasing the soft start time. In other words, in addition to controlling the pH to 3-4, by simultaneously controlling the applied voltage, it can be in the range of 4 wt% to 20 wt%, and the electrodeposition coating film adhered to the electrodeposition coating object The slidability can be improved when the amount of polytetrafluoroethylene deposited therein becomes an appropriate amount.

  That is, in the present invention, in managing the amount of polytetrafluoroethylene deposited, the liquid management width of the electrodeposition liquid 1 is set to pH 3 to 4 (in this case, the conductivity is 450 to 550 μs / cm), and further, electricity. It has been found that conditions where the applied voltage is about 50 V to 180 V and / or soft start is 10 seconds to 40 seconds during the electrophoresis reaction are most preferable. By controlling the amount of polytetrafluoroethylene deposited in this way, the slidability can be improved.

  Further, the electrodeposition coating target can be applied to other than the above-mentioned sliding portion of the card reader, and may be a sliding portion of a lead screw, for example.

  The electrodeposition coating material, the electrodeposition coating film, the sliding member, and the card reader according to the present invention can also be applied to applications that require slidability and discharge performance. It is useful as a material that can enhance the versatility of the material.

It is process explanatory drawing for demonstrating typically the process of the electrodeposition coating using the electrodeposition coating material which concerns on embodiment of this invention. It is a figure which shows the correlation with the precipitation amount of the polytetrafluoroethylene of the electrodeposition coating film quantified by SEM method which concerns on embodiment of this invention, and the density | concentration of a dispersion liquid. It is sectional drawing which shows the internal structure of the card reader in embodiment of this invention. It is a figure which shows the experimental result conducted using the card reader which concerns on embodiment of this invention. It is a figure which shows the experimental result conducted using the card reader which concerns on embodiment of this invention. It is a figure which shows the experimental result conducted using the card reader which concerns on embodiment of this invention. It is a figure which shows the experimental result conducted using the card reader which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrodeposition liquid 2 Electrodeposition object 3 Electrolysis tank 4 DC power supply 5 Electrodeposition coating 11 Card reader 12 Frame 13 Bottom part 14, 15 Side board part 16 Card path 17 Magnetic head 18 Coating film 19 Insertion card

Claims (7)

  An electrodeposition coating material of an electrodeposition coating film comprising a heat-resistant resin material as a base material and having a solid lubricant and a conductive inorganic filler added thereto, wherein the electrodeposition liquid containing the dispersion of the electrodeposition coating material An electrodeposition coating material, characterized in that the pH is maintained within a control range of pH 3-4.   2. The electrodeposition coating material according to claim 1, wherein polyimide is used as the heat-resistant resin material, polytetrafluoroethylene is used as the solid lubricant, and graphite is used as the solid lubricant and a conductive inorganic filler. .   The polyimide contains 10 to 20% by weight, the polytetrafluoroethylene contains 20% to 5% by weight of the polyimide, and the graphite contains 2 to 5% by weight of the polyimide. The electrodeposition coating material according to claim 1 or 2.   The amount of polytetrafluoroethylene deposited in the quantitative value obtained by semi-quantitative analysis of the elements with a scanning electron microscope of the electrodeposition coating film is 4% to 25% in terms of the weight ratio of fluorine to carbon on the surface of the electrodeposition coating film. The electrodeposition coating material according to claim 1, wherein the electrodeposition coating material is provided.   The amount of polytetrafluoroethylene deposited on the surface of the electrodeposition coating film is equal to or greater than the amount of polytetrafluoroethylene deposited in the electrodeposition coating film. The electrodeposition coating film according to claim 4, which is characterized by the following.   The sliding member according to any one of claims 1 to 5, further comprising a sliding portion in which the electrodeposition coating film is formed of the electrodeposition coating material. 7. The card reader according to claim 6, wherein a card travel reference surface is configured by using the sliding member.

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