JP2007169310A - Coating agent and portable electronic instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating film without making fingerprints or peeled off parts conspicuous. <P>SOLUTION: This coating film is formed on the surface of a portable information instrument. The coating agent for forming the coating film contains a resin and fine particles having 0.3-1.0 μm range particle diameter. Further, the mass ratio of the resin to fine particles is (100:20 to 500). As a result, on the coating film, the glossiness of a zone of fingerprint oils and fats and a zone of other than the fingerprint oils and fats resemble closely with each other so as not to make the fingerprint conspicuous. In addition, since it is possible to make the coating film thin, the peeled off parts become not conspicuous. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a coating film that makes fingerprint marks and peeled portions inconspicuous.

  The casing of a portable electronic device such as a notebook computer, PDA, or mobile phone is preferably lightweight so that it is easy to carry and scratches and scratches are less likely to occur on the surface. Therefore, a lightweight, inexpensive, and relatively strong aluminum alloy is used as a structural material, and the surface is covered with a protective film having a high hardness such as a titanium compound. However, since the surface of a metal film having high hardness such as a titanium compound is mirror-like, if the fingerprint oil or fat adheres, dirt is noticeable and the aesthetic appearance is impaired.

  As a countermeasure, a coating agent in which fine particles with a particle size of 3 to 15 μm are mixed in a transparent paint is applied to the surface of the protective film, and the glossiness (gross) of the part where the fingerprint oil is attached and the other part are approximated. The method is adopted. Since there is a large difference in hardness between the coating film and the protective film, the coating film tends to peel off. When the amount of fine particles necessary for adjusting the glossiness is mixed in the paint, the particle size of the fine particles is relatively large, so that the coating film is less transparent. When the protective film is exposed due to the occurrence of scratches or scratches on the surface of the housing, there is a problem that the color difference between the coating film and the protective film is conspicuous and the appearance is impaired.

  In addition, in order to make the place where the coating film is peeled off while adjusting the glossiness, the transparency of the coating film is ensured by mixing fine particles having a particle diameter of 0.01 μm or less with a transparent paint, There is a method of approximating the glossiness to that of fingerprint oil. In this case, since the transparency of the coating film is ensured, even if the protective film is exposed, the portion is hardly noticeable.

Patent Document 1 discloses a film-formed product that can reduce the occurrence of light interference even if fingerprint oil or machine oil adheres to the surface, thereby making the adhesion trace inconspicuous. As described in the summary, the film-formed product of this document is formed as a transparent cured film having a composition in which fine particles are uniformly dispersed in a film-forming resin. One of the film-forming resin and the fine particles has a refractive index smaller than the refractive index n of the fingerprint oil or machine oil, and the other has a refractive index larger than the refractive index n, and the cured film has a refractive index. Is adjusted to be substantially n. As a result, it is possible to reduce the interference of light that occurs between a cured film having a refractive index substantially equal to that of fingerprint oil or machine oil. The fine particles contained in the cured film are made of titanium nitride or silicon monoxide as a material, have a particle diameter of 0.05 to 0.2 μm, and the mixing ratio with respect to the paint main agent is 1 to 90% by mass ratio. .
JP 2004-181735 A

  Conventionally, attention has been focused on the transparency of the coating film as a point of focus when forming a coating film that is not conspicuous even when the glossiness is approximated. In this case, it was considered necessary to ensure transparency by setting the particle diameter of the fine particles to 0.01 μm or less. Hereinafter, in this specification, the property that the place where the coating film is peeled off is inconspicuous is referred to as peeled portion aesthetics. Moreover, when adjusting a refractive index with the technique described in patent document 1, it is necessary to make the particle diameter of microparticles into 0.2 micrometer or less.

  In the conventional technique, in order to form a coating film in which fingerprint marks are not conspicuous by adjusting glossiness and refractive index, the particle diameter of the fine particles mixed into the coating agent is very small, such as 0.01 μm or less or 0.2 μm or less. There was a need to make things. Since it is difficult to produce fine particles having such a particle size by mechanically pulverizing large fine particles, the production cost increases.

  Further, in the technique described in Patent Document 1, when the particle diameter is 0.2 μm or more in the paragraph 0035, the particle diameter may be greater than or equal to the film thickness of the cured film, which may deteriorate the film strength of the cured film. Since it is described as being present, the particle size cannot be 0.2 μm or more. Since the surface coating layer formed on the casing of portable electronic devices is often carried in bags or pockets together with metals such as keys and stationery, the surface coating layer may be peeled off due to scratches or scratches. In this case, it is necessary to keep aesthetics.

  Therefore, the coating film formed on the surface of the portable electronic device is required to have a function of keeping the peeled portion aesthetic so as not to make the peeled place inconspicuous, in addition to the function of making the fingerprint oil and fat inconspicuous. SUMMARY OF THE INVENTION An object of the present invention is to provide a coating agent for forming a coating film that makes a fingerprint mark and a peeled area inconspicuous. Furthermore, the objective of this invention is providing the portable electronic device provided with the coating film formed with such a coating agent.

  In the present invention, the glossiness is adjusted by selecting the particle diameter while paying attention to a new parameter such as the thickness of the coating film, unlike the conventional technique in which the particle diameter is selected by using transparency and refractive index as parameters. Furthermore, in the present invention, the thickness of the coating film is made as thin as possible. The coating agent concerning this invention contains resin and the microparticles | fine-particles which have a particle diameter in the range of 0.3 micrometer-1.0 micrometer. The mass ratio of the resin to the fine particles is 100: 20 to 500. When the coating agent having such a configuration is applied to the surface of the mirror-like base layer to form a coating film, the fingerprint trace becomes inconspicuous because the glossiness of the fingerprint fat and oil is similar to the glossiness of portions other than the fingerprint fat. In addition, when particles having a particle diameter in the range of 0.3 μm to 1.0 μm are mixed in the resin, the coating film can be applied so that the thickness of the coating film becomes thin. The step between the protective film and the protective film is lowered, and the peeled portion aesthetics can be maintained.

  The coating agent may contain fine particles having various particle sizes in the range of 0.3 μm to 1.0 μm, but fine particles having a particle size close to 0.3 μm are more than fine particles having a particle size close to 1.0 μm. In many cases, when the mass ratio of the resin and the fine particles is set to 100: 100 to 500, the glossiness and the thickness of the coating film can be easily adjusted. Further, when the number of fine particles close to 1.0 μm is larger than the fine particles close to 0.3 μm, the gloss ratio and the thickness of the coating film are set when the mass ratio of the resin to the fine particles is 100: 20 to 200. Is easy to adjust. As the resin, known materials can be used as paints for portable electronic devices such as melamine resins and epoxy resins having a molecular weight in the range of 500 to 2000. However, using a transparent resin improves the transparency of the coating film. Thus, the aesthetic appearance of the peeled portion can be kept better.

  A multilayer protective film including a titanium nitride layer has high hardness and is difficult to peel off, so it is convenient for use in portable electronic devices, but the surface of the titanium nitride layer becomes a mirror surface and fingerprint marks are conspicuous. . Since the coating film formed by applying a coating agent in which the particle diameter of the fine particles and the mass ratio of the resin and fine particles are adjusted on the titanium nitride layer has an approximate glossiness, fingerprint marks are not noticeable. Moreover, since the thickness of the coating film can be 0.5 μm or less, the peeled portion aesthetics can be maintained.

  According to the present invention, it has been possible to provide a coating agent for forming a coating film that makes a fingerprint mark and a peeled area inconspicuous. Furthermore, according to the present invention, a portable electronic device provided with a coating film formed with such a coating agent could be provided.

  FIG. 1 is a perspective view showing the outer shape of the notebook computer 1. 2A is a cross-sectional view of the casing of the notebook computer 1, and FIG. 2B is a diagram illustrating a state where the scratch 119 is generated in the coating film 100. FIG. 2A, in the case of the notebook computer 1, the body 11 is formed of an aluminum alloy, and the multilayer coating film 10 is formed thereon as a protective film for protecting the case from scratches and scratches. ing. On the surface of the multilayer coating film 10, the coating film 100 is formed by applying the coating agent according to the present embodiment so as not to make fingerprint marks conspicuous. The coating film 100 is required to make the fingerprint trace inconspicuous, to be easily attached to the metal layer, and to be durable and inexpensive.

  The multilayer coating film 10 has a three-layer structure of a bright nickel layer 13, a nickel phosphate layer 15, and a titanium nitride layer 17. The body 11 need not be limited to an aluminum alloy, and any type of metal material that can be electroplated can be used. The aluminum alloy 11 has a Vickers hardness (Hv) of 100 to 200. A bright nickel layer 13 having a thickness of 5 to 15 μm is formed on the surface of the aluminum alloy 11 by electroplating. Hv of the bright nickel layer is 500, which is larger than that of the aluminum alloy. The bright nickel layer also serves to protect the aluminum alloy from the low pH electrolyte used in the subsequent plating step of the nickel phosphate layer 15.

  On the surface of the bright nickel layer 13, a nickel phosphate layer 15 is further formed by electroplating to a thickness of 3 μm to 15 μm. Hv of the nickel phosphate layer 15 is 640, which is larger than Hv of the bright nickel layer 13. The bright nickel layer 13 and the nickel phosphate layer 15 constitute an intermediate layer. A titanium nitride layer 17 is formed on the surface of the nickel phosphate layer 15 by physical vapor deposition such as sputtering or ion plating. The titanium nitride layer 17 is a surface layer formed on the outermost side of the multilayer coating film 10 and has a thickness of 0.05 μm to 10 μm. Hv of the titanium nitride layer 17 is 800 to 1100, which is larger than Hv of the nickel phosphate layer 15. The reason why the physical vapor deposition method is employed for forming the titanium nitride layer 17 is to improve adhesion to the nickel phosphate layer 15 serving as a base layer so that it is not easily peeled off.

  The hardness of the multilayer coating film 10 was measured by a coin test method because it cannot be directly measured by a Vickers hardness tester. In the coin test method, a scratch is formed with a coin to which a force of 10 kg / cm 2 is applied in advance on the surface of a reference material whose Hv is known in advance, and the scratch is also formed on the multilayer coating film 10 by the same method. Then, when the traces of both scratches are compared and approximated, Hv of the reference material is adopted as Hv of the multilayer coating film 10. As a result, the Hv of the multilayer coating film 10 was 800 to 1100. The reason why a relatively large hardness was obtained despite the thin surface layer was due to the action of the intermediate layer having a hardness higher than that of the aluminum alloy 11.

  The intermediate layer can be freely selected as long as it is a material capable of electroplating having an intermediate hardness between the base material and the surface layer. For example, the hardness may be selected from a single element selected from copper, nickel, and chromium, or a composition containing two or more elements, and the layers may be sequentially stacked. As the number of intermediate layers increases, the peel resistance improves, but the cost increases, so about two layers are desirable.

  Next, the coating film 100 will be described. The principle that the coating film 100 can make the fingerprint mark inconspicuous is that fine particles are mixed into the paint to approximate the glossiness of the fingerprint oil and the gloss of the area other than the fingerprint oil. The paint is composed of basic elements composed of a resin, a pigment, and a solvent. The resin is a portable electronic device such as durability that is difficult to be decomposed by light, oxygen, water, acid, alkali, etc., affinity for an underlayer such as the titanium nitride layer 17, fluidity during coating, and curability in the drying process. The material is selected from materials having general functions required for the housing of the device.

  As the resin according to the present embodiment, any one kind selected from melamine resin, epoxy resin, urethane resin, phenol resin, alkyd resin, or a mixture thereof can be adopted. The coating film 100 needs to make the fingerprint marks inconspicuous while adhering to the surface of the multilayer coating film 10, but was peeled off when it was partially peeled off from the surface of the multilayer coating film 10 due to scratches or scratches. It is necessary to have the aesthetics of the peeling part so that the place is not conspicuous. Therefore, it is desirable that the paint is transparent when the base is a metal layer, but when the base is plastic, it is desirable to mix a pigment for coloring the plastic. For the solvent, a well-known material is selected in order to ensure fluidity during coating.

  The fine particles are produced using any one kind selected from silicon dioxide, titanium dioxide, talc, and kaolinite, or a mixture of a plurality of kinds as raw materials. Glossiness is defined as the ratio of direct reflection to diffuse reflection of an object. By mixing fine particles into the resin, the ratio of the diffuse reflection from the particles on the surface of the coating film 100 increases, and the ratio of the direct reflection from the fingerprint oil to the diffuse reflection and the diffusion of the direct reflection from the region other than the fingerprint oil. The ratio to the reflection approaches and the glossiness of both approaches. When the thickness of the coating film 100 is small, as shown in FIG. 2B, the area of the step portions 113 and 115 with respect to the surface 117 of the base layer of the coating film 100 generated in the scratch 119 becomes small, so that the peeling occurs. The part becomes inconspicuous. Therefore, in order to ensure the peeled portion aesthetics, it is necessary to make the coating film 100 as thin as possible. In the coating agent according to the present embodiment, since the fine particles having a particle diameter of 0.3 μm to 1.0 μm are mixed in the resin, the thickness of the coating film can be reduced. Therefore, the coating film 100 can adjust the glossiness and retain the peeled portion aesthetics.

  FIG. 3 is a diagram schematically illustrating the relationship between the thickness of the coating film 100 and the particle diameter of the fine particles. A coating film 100 is formed on the titanium nitride layer 17 as an underlayer, which is coated with a liquid coating agent and then dried and cured. The coating film 100 is formed by mixing well-known additives for adjusting the function in addition to the fine particles 101 and the resin 103. The coating agent is diluted with a diluent to adjust the flowability and is applied to the controlled thickness in a known manner.

  The coating agent can be applied so that the minimum thickness t of the resin 103 where the fine particles 101 are not present in the coating film 100 is about half of the maximum particle size of the fine particles contained in the coating agent. Since the thickness of the coating film 100 is different between the place where the fine particles exist and the place where only the resin is present, the thickness of the coating film is defined as the minimum thickness of the resin portion in this specification. The thickness of the coating film 100 can be measured in a non-contact manner by cutting the coated housing and checking the cross section with a microscope, or using a laser measuring device. When the coating film 100 has a scratch 119 or peels off, the surface 111 of the coating film 100 and the surface of the base layer are formed on the resin 103 as described with reference to FIG. The cross-sections 113 and 115 whose upper and lower sides are defined at 117 are formed. In the coating film 100, since the areas of the cross sections 113 and 115 are small, the peeled portion is hardly noticeable, and the peeled portion aesthetics can be maintained.

  In order to ensure the peelable part aesthetics, a sensory test was conducted by 12 inspectors in order to determine the allowable thickness of the coating film. The sensory test was carried out by a method in which a coating film having a thickness of 8 levels was formed between 0.5 μm and 2 μm, and the size and conspicuousness of the level difference were inspected. As a result, it was found that when the thickness of the coating film was 0.5 μm or less, the peeled portion aesthetics were good, and when it exceeded 1.0 μm, the peeled portion was conspicuous. In the coating agent according to the present embodiment, by setting the upper limit of the particle diameter to 1.0 μm, the thickness of the coating film can be reduced to 0.5 μm or less. It can be done.

  The particle diameter of the fine particles mixed in the conventional coating film for adjusting the glossiness is 3 μm to 15 μm. In this case, the thickness of the coating film is about 1.5 μm or more. On the other hand, the thickness of the coating film 100 according to the present embodiment is 0.5 μm or less by using fine particles of 0.3 μm to 1.0 μm, and is reduced to about 1/3 compared with the conventional case. be able to.

  As the amount of fine particles mixed in the resin increases, the thickness of the coating film becomes governed by the particle diameter of the fine particles, so the mixing ratio of the fine particles to the resin is set to 20 to 500 with respect to the resin 100 in mass ratio. ing. The fine particles to be mixed into the paint are composed of particles having various particle sizes in order to use the fine particles produced by pulverizing the large particles and removing the large fine particles with a filter. When the number of fine particles close to 0.3 μm is larger than the fine particles close to 1.0 μm, it is desirable that the ratio of fine particles to resin is 100 to 500 fine particles to resin 100 by mass ratio. When the number of fine particles close to 1.0 μm is larger than the fine particles close to 0.3 μm, the ratio of fine particles to resin is desirably about 20 to 200 fine particles to resin 100 in terms of mass ratio.

  The lower limit of the mass ratio of the fine particles to the resin is set as a range in which glossiness can be adjusted so that fingerprint marks are not noticeable. When the amount of fine particles decreases, a sufficient amount of diffuse reflection from the fine particles cannot be obtained, and the glossiness cannot be adjusted. In addition, the upper limit of the mass ratio of the fine particles is set to ensure the reliability of the coating film in addition to the purpose of managing the thickness of the coating film. When the amount of fine particles increases, the particles approach each other and cause cohesive failure, and the coating film becomes brittle and lacks reliability.

  If the particle diameter is larger than 1.0 μm, the coating film cannot be formed thin, so that the peeled portion becomes conspicuous and the function of maintaining the peeled portion aesthetics is deteriorated. Further, as the particle diameter of the fine particles becomes larger than 1.0 μm, the transparency of the coating film 100 gradually decreases, so that when the underlayer is a metal, the difference in color between the underlayer and the coating film increases. , The function of maintaining the peeled portion aesthetics is reduced. Further, as the particle diameter of the fine particles becomes smaller than 0.3 μm, the production of the fine particles becomes increasingly difficult and the cost increases. In addition, in order for the resin to be three-dimensionally bonded and cured on the base layer, the resin thickness needs to be at least about 0.4 μm to 0.5 μm, so the coating film cannot be made thinner. Therefore, even if the particle diameter of the fine particles is 0.3 μm or less, it is not effective in thinning the coating film.

  In order to manufacture a coating agent for forming the coating film 100, first, a dispersion machine is used for suspending relatively large fine particles such as silicon dioxide or titanium dioxide and a relatively high boiling point and high viscosity such as glycol ester. A solvent is added at a constant ratio and stirred for a long time to produce fine particles having a particle size of 0.3 μm to 1.0 μm. As the disperser, a pebble mill, a sand mill, a roll mill, or a glass mill can be used. Subsequently, the resin is added, and after stirring for a predetermined time, fine particles having a particle size of 1.0 μm or more are removed with a filter.

  Even if fine particles having a small particle diameter are initially introduced into the resin and stirred, so-called flocking occurs in which the fine particles stick to each other, and the particle diameter of the fine particles cannot be maintained within a predetermined range. According to the manufacturing method according to the present embodiment, large particles and small particles are simultaneously present in the disperser so that the resin surrounds the small particles, so that the particles having a predetermined particle size are appropriately obtained. Distributed coatings can be produced. Subsequently, a diluent is mixed with the resin and fine particle mixture to form a coating agent. As the diluting solvent, a coating film having a thin and uniform thickness can be formed by mixing a very volatile solvent and a very volatile solvent. As a method of applying the coating material to the underlayer, a known method such as brush coating, spray coating, or roll coating can be employed.

  Although the present invention has been described with the specific embodiments shown in the drawings, the present invention is not limited to the embodiments shown in the drawings, and is known so far as long as the effects of the present invention are achieved. It goes without saying that any configuration can be adopted.

  The present invention can be applied to a coating film that is easy to adhere fingerprint oil and fat and that does not stand out even if it is peeled off.

It is a perspective view which shows the external shape of a notebook computer. It is sectional drawing of the housing | casing of a notebook computer. It is a figure explaining the thickness of a coating film.

Explanation of symbols

100 Coating Film 101 Fine Particle 103 Resin 119 Scratch

Claims (12)

A coating agent for forming a coating film on the surface of a portable information device,
Resin,
Fine particles having a particle diameter in the range of 0.3 μm to 1.0 μm,
The coating agent whose mass ratio of the said resin and the said microparticles has become a ratio of 100: 20-500.   2. The coating agent according to claim 1, wherein the mass ratio is 100: 100 to 500 when the fine particles having a particle diameter close to 0.3 μm are larger than the fine particles having a particle diameter close to 1.0 μm.   2. The coating agent according to claim 1, wherein the mass ratio is 100: 20 to 200 when the number of fine particles having a particle diameter close to 1.0 μm is larger than the number of fine particles having a particle diameter close to 0.3 μm.   The coating agent according to claim 1, wherein the fine particles are composed of any one element or a plurality of elements selected from the group consisting of silicon dioxide, titanium dioxide, talc, and kaolinite.   The coating agent according to claim 1, wherein the resin is composed of any one element or a plurality of elements selected from the group consisting of a melamine resin, an epoxy resin, a urethane resin, a phenol resin, and an alkyd resin.   The coating agent according to claim 1, wherein the resin is transparent.   The coating agent according to claim 1, wherein the resin has a molecular weight of 500 to 2,000. A portable electronic device comprising a housing, wherein the housing is
A structure,
A protective film formed on the surface of the structure;
A coating film applied on the protective film,
The portable electronic device in which the said coating film was formed with the coating agent in any one of Claims 1-7.   The portable electronic device according to claim 8, wherein the protective film has a multilayer structure in which an uppermost layer is a titanium nitride layer.   The portable electronic device according to claim 8, wherein a surface of the protective film is in a mirror state.   The particle diameter of the fine particles and the mass ratio of the resin and the fine particles are adjusted so that the glossiness of the fingerprint oil and fat adhering to the coating film and the glossiness of the area of the coating film other than the fingerprint oil and fat are approximated. The portable electronic device according to claim 8. The portable electronic device according to claim 8, wherein the coating film has a thickness of 0.5 μm or less.

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