JP6932341B2 - Vehicle parts and their manufacturing methods - Google Patents

Description

The present invention relates to a vehicle component provided with a transparent portion and a method for manufacturing the same.

In a lamp unit or the like, which is a vehicle part having a transparent part, when the surface of the lens is cooled by the outside air while high humidity air has entered the housing, the water vapor inside condenses and the inner surface of the lens becomes cloudy. May occur. In order to prevent such fogging on the inner surface of the lens, in the technique described in Patent Document 1, an anti-fog paint is applied to the inner surface of the lens. The antifogging coating reduces the surface tension of water adhering to the surface of the coating film by the surface-active action of the surfactant to a water contact angle of 30 ° or less, improves the wettability to water, and generates fine water droplets. Instead, the antifogging property is ensured by forming a water film.

Further, there is known a technique of forming fine irregularities on the outermost surface of a functional agent to increase effects such as hydrophilicity and anti-fog property. For example, in the technique of Patent Document 2, a water film anti-fog function such as a cover plate of an instrument is realized by improving the wettability of a hydrophilic resin by utilizing nano-concavities and convexities controlled in a gap below visible light. ing.

Similarly, Patent Documents 3 to 6 and the like are known as a method for increasing the function of the hydrophilic film by using nano-concavities and convexities. When the liquid placed on the concavo-convex structure comes into complete contact with the solid surface, the concavo-convex structure of the surface causes the actual surface area to be larger than the apparent surface area. As a result, the wettability is emphasized. For example, in the case of water film anti-fog, it is known that the anti-fog function, the hydrophilic function, etc. are increased by forming the unevenness on the surface as compared with the case where the uneven surface is not formed. ing. The water contact angle of the film surface on the side where the nanostructure is formed is generally required to be 40 ° or less.

Japanese Unexamined Patent Publication No. 2011-140589 Japanese Unexamined Patent Publication No. 2015-78924 Japanese Unexamined Patent Publication No. 2015-13291 Japanese Unexamined Patent Publication No. 2015-3519 Japanese Unexamined Patent Publication No. 2011-53334 Japanese Unexamined Patent Publication No. 7-82397

In the technique described in Patent Document 1, when the amount of water in the housing of the lamp unit exceeds the allowable amount of water retention of the anti-fog paint, water flows along the surface of the anti-fog paint. As a result, the surfactant of the anti-fog paint flows over time, and the surfactant action is reduced. That is, it is difficult to obtain a long-term anti-fog effect by applying the anti-fog paint to the inner surface of the lens.

Further, since it is necessary to apply a coating film, if anti-fog property is given to a closed space of a free curved surface such as a head lamp or a tail lamp, liquid residue or uneven application occurs, which makes it difficult to manufacture a good product and the yield is poor. In addition, the adhesion between the plastic base material and the coating film is also a problem, and in some cases, film peeling or film cracking occurs.

The techniques of Patent Documents 2 to 6 are techniques for obtaining a hydrophilic function and an anti-fog function that exceed the characteristics of the material by using the uneven structure, but as in the case of Patent Document 1, the hydrophilic function is lost due to the adhesion of dirt. It is easy and difficult to maintain the function for a long period of time.

The present invention has been made to solve the above problems, and the problem to be solved by the present invention is to prevent fogging of the transparent portion for a long period of time only by using the material of the transparent portion and the uneven structure. Is to do so.

The above-mentioned problems are solved by the invention of each claim. The invention of claim 1 is a vehicle component provided with a transparent portion, and a large number of protrusions having a size of half a wavelength or less of visible light are formed at predetermined intervals on the back surface of the transparent portion to which the outside air does not come into direct contact. The protrusion dimension and the diameter dimension of the protrusion are set to 150 nm to 400 nm, the gap dimension of the protrusions adjacent to each other is set to 150 nm to 400 nm, and a plane representing the smoothness of the protruding end face of the protrusion. The degree Ra is 30 nm or less, and a large number of the protrusions are formed independently.

Generally, when the warm air inside the transparent portion is cooled by the outside air outside the transparent portion, the water vapor in the air inside the transparent portion is attracted to the back surface of the transparent portion. According to the present invention, a large number of protrusions having a size of half a wavelength or less of visible light are formed at predetermined intervals on the back surface of the transparent portion. That is, the protruding structure formed on the back surface of the transparent portion is also an aggregate of concave recessed portions. Therefore, the water vapor attracted to the back surface of the transparent portion adheres to the flat surface between the recessed portion and grows, and the adhered water vapor grows individually and becomes water droplets. However, since the dimension of the plane between the recess and the recess is less than half the wavelength of visible light, it is possible to prevent water vapor from growing beyond the dimension of the plane between the recess and the recess to become water droplets. .. Therefore, it becomes easy to keep the water droplet in a size of half a wavelength or less of visible light. Then, the grown water droplets are held at the position of the protrusions or the position of the recessed portion at a contact angle larger than the contact angle of the water droplets on a flat surface where no protrusions or the like are present due to the action of surface tension. That is, when there are a large number of protrusions on the back surface of the transparent portion, it is difficult for the water droplets to gather together as compared with the case where the back surface of the transparent portion is a flat surface, and a large number of water droplets are held in a relatively small size. Further, since the size of the protrusion is less than half the wavelength of visible light, the size of the water droplet attached to the protrusion is also less than half the wavelength of the visible light and cannot be seen by humans. In this way, since the water droplets are invisible to humans, it is not recognized that the transparent portion has become cloudy. Further, since the protrusions do not change with time, it is possible to prevent fogging on the inner surface of the transparent portion for a long period of time.

According to the invention of claim 2 , the protruding dimension of the protrusion is 1 time or more and 3 times or less the gap size of the protrusions adjacent to each other.

According to the invention of claim 3, the contact angle when the back surface of the transparent portion on which the protrusion is formed is a flat surface is set to 60 ° to 100 °.

According to the invention of claim 4, the material of the transparent portion is a plastic material.

The invention of claim 5 is provided with a transparent portion, outside air projection of the half-wavelength size of visible light on the back surface of the transparent portion is not in direct contact are formed a large number at predetermined intervals, the projection of the projection The dimensions and diameter dimensions are set to 150 nm to 400 nm, the gap dimensions of the protrusions adjacent to each other are set to 150 nm to 400 nm, and the flatness Ra representing the smoothness of the protruding end faces of the protrusions is 30 nm or less. , A large number of the protrusions are independently formed as a method for manufacturing a vehicle part, and a reactive ion etching method (Reactive Ion Etching) is used for a molding surface for molding the back surface of the transparent portion in an injection molding mold. It has a step of forming the transparent portion by using the injection molding mold provided with the molding surface, and a step of injection molding the transparent portion.
As described above, by injection molding, protrusions having a size of half a wavelength or less can be formed on the back surface of the transparent portion, so that the protrusions can be easily formed.

According to the invention of claim 6 , the molding surface of the injection molding die is manufactured of a copper alloy. Therefore, since the thermal conductivity of the molding surface of the injection molding die is increased, the temperature control becomes easy, and the material of the transparent portion can be reliably supplied to the unevenness of the molding surface.

According to the present invention, anti-fog of transparent portions of vehicle parts can be prevented for a long period of time.

It is an overall perspective view of the headlamp unit which is a vehicle component which concerns on Embodiment 1 of this invention. It is a schematic vertical cross-sectional view (II-II arrow cross-sectional view of FIG. 1) of the headlamp unit. FIG. 5 is an enlarged schematic vertical sectional view of the back surface of the outer lens of the headlamp unit (enlarged sectional view taken along line III in FIG. 2). It is an enlarged schematic perspective view of the back surface of the outer lens of the headlamp unit. It is a schematic vertical sectional view of the injection molding mold which molds the outer lens of the headlamp unit. It is an enlarged vertical sectional view of the molding surface of the injection molding die which molds the outer lens of the headlamp unit (VI arrow view schematic enlarged view of FIG. 5). It is a schematic vertical sectional view which shows the state of dew condensation in the housing of the headlamp unit. It is a schematic vertical sectional view which shows the state of dew condensation in the housing of the headlamp unit. It is an enlarged vertical sectional view on the back surface of the outer lens of the headlamp unit which concerns on the modification.

[Embodiment 1]
Hereinafter, vehicle parts according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 9. The vehicle component according to the present embodiment is the headlamp unit 20 of the vehicle 10 which is an example of the lamp unit. The front, rear, left, right, and top and bottom shown in the figure correspond to the front, back, left, right, and top and bottom of the vehicle 10 to which the headlamp unit 20 is attached.

<Outline of configuration of headlamp unit 20>
The headlamp unit 20 is a pair of left and right lamps having the same specifications, and is formed symmetrically. As shown in FIGS. 1 and 2, the headlamp unit 20 includes a housing 21 having an opening 21h on the front surface side. A reflector 23 is provided in the housing 21 so as to cover the inner wall surface 21w of the housing 21. Further, a light source 25 made of an LED or the like is installed at the position of the bottom of the housing 21 and the reflector 23. The opening 21h on the front surface side of the housing 21 is closed by the outer lens 30. Further, a breathing hole 27 of the headlamp unit 20 is provided at the end position of the bottom portion of the housing 21.

<About the outer lens 30>
As shown in FIG. 2, the outer lens 30 transmits the light of the light source 25 on the inner peripheral side of the flange-shaped lens edge portion 32 fitted from the outside to the opening edge portion 21e of the housing 21 and the lens edge portion 32. It includes a lens body 34. A large number of protrusions 35 for preventing fogging are formed on the back surface 34b (inner surface) of the lens body 34. As described above, the outer lens 30 corresponds to the transparent portion of the present invention.

<About protrusion 35>
As shown in FIGS. 3 and 4, the protrusion 35 of the outer lens 30 (lens body 34) is formed in a truncated cone shape, for example, and the protrusion 35 has a protruding dimension of H and the protrusion 35 has a diameter of W. , The dimension between the adjacent protrusions 35 is set to L. Dimension H, Dimension W, and Dimension L are approximately equal values, and are set to dimensions of half a wavelength or less of visible light. In the outer lens 30 according to the present embodiment, for example, dimension H = dimension W = dimension L = 150 nm to 200 nm (nanometer) is set. Therefore, many protrusions 35 of the outer lens 30 cannot be seen with the naked eye.

<About the size of the protrusion 35>
The large number of protrusions 35 are for preventing the water vapor in the headlamp unit 20 from growing beyond half the wavelength of visible light when it adheres to the inner surface of the outer lens 30. Here, the growth of water droplets is determined by the coastal nuclear radius Rc obtained by the relationship between the free energy G (G = H-TS) of Gibbs and the interfacial moving velocity V. Therefore, if the gap dimension of the unevenness on the inner surface of the outer lens 30 caused by the protrusion 35 is too large than the coastal nucleus radius Rc, water droplets grow large and become more than half the wavelength of visible light, which causes fogging. On the contrary, if the gap size of the unevenness is too small, the grown water droplets get over the unevenness and become more than half the wavelength of visible light, which also causes fogging.

In the present embodiment, in order to set an appropriate gap size or the like of unevenness, the size or the like between adjacent protrusions 35 is set based on the coastal nuclear radius Rc.
Here, the coastal nuclear radius Rc is Rc = 2γ ÷ (ΔH−TΔS) ... (1)
RcforV = 0 ... (2)
It is represented by.
In the above equation, γ is the interfacial tension. That is, at the interface between water and air, when the room temperature is 1 atm, the coastal nuclear radius Rc is about 366.4 nm according to the equations (1) and (2). Therefore, the dimensions of the protrusions 35 and the dimensions between the adjacent protrusions 35 are preferably 400 nm or less. Further, it is desirable that the dimension between the adjacent protrusions 35 is 150 nm or more so that the grown water droplets do not get over the unevenness. Therefore, in the present embodiment, as described above, the dimension H = dimension W = dimension L = 150 nm to 200 nm in the protrusion 35 is set.

Further, the flatness Ra representing the smoothness of the protruding surface (tip surface) of the protrusion 35 is preferably 30 nm or less in order to suppress the growth of water droplets and the like. Further, the higher the protrusion 35, the more the interfacial movement between the irregularities can be restricted, and the growth of water droplets can be suppressed. Therefore, specifically, the height dimension of the protrusion 35 is preferably 1 time or more and 3 times or less the size between the adjacent protrusions 35. Further, the contact angle of the inner surface of the outer lens 30 on which the protrusion 35 is formed in a flat state is preferably within 60 ° to 100 °. Here, in the present embodiment, the anti-fog effect can be exhibited under the conditions of a humidity of 21% at a temperature of 24 ° C. and a humidity of 62% at a temperature of 12 ° C.

<Manufacturing method of outer lens 30>
The outer lens 30 is formed by melting materials such as polyacrylic, polystyrene, polycarbonate, synchroolefin polymer, and synchroolefin copolymer and press-fitting them into the injection molding mold 40. As shown in FIG. 5, the injection molding die 40 includes a first molding die 41 for molding the front surface side of the outer lens 30, and a second molding die 43 for molding the back surface side of the outer lens 30. Then, in a state where the first molding die 41 and the second molding die 43 of the injection molding die 40 are molded, a space Sk for molding the outer lens 30 is formed inside the injection molding die 40. The first molding die 41 of the injection molding die 40 is formed with a first molding surface 41f for molding the front surface 34f (see FIG. 2) of the outer lens 30, and the second molding die 43 is formed with the back surface 34b of the outer lens 30. A second molding surface 43f is formed.

As shown in FIG. 6, a large number of recesses 43z are formed on the second molding surface 43f of the second molding mold 43 in order to form a large number of protrusions 35 on the back surface 34b of the outer lens 30. The recess 43z of the second molding surface 43f of the second molding die 43 is molded by using a reactive ion etching method (Reactive Ion Etching). Further, the second molding die 43 is manufactured by using a copper alloy having a high thermal conductivity in the second molding surface 43f and a portion in the vicinity thereof. Therefore, the temperature control of the second molding surface 43f and the portion in the vicinity thereof at the time of injection molding becomes easy, and the material such as polystyrene can be reliably supplied to the recess 43z of the second molding surface 43f. By injection molding the outer lens 30 using the injection molding mold 40 having the above configuration, a large number of protrusions 35 can be formed on the back surface 34b of the outer lens 30.

<About the function of the protrusion 35 of the outer lens 30>
When high-humidity air enters the headlamp unit 20 and the warmed air is cooled by the outside air, as shown in FIG. 7, the initial nucleus W0 (hereinafter referred to as water vapor) of water vapor in the headlamp unit 20 is released. It is attracted to the back surface 34b of the outer lens 30. Here, on the back surface 34b of the outer lens 30, a large number of protrusions having a size (150 nm to 200 nm) of half a wavelength or less of visible light are formed. The protrusion dimension H of the protrusion 35, the diameter dimension W of the protrusion 35, and the dimension L between the adjacent protrusions 35 are set to substantially equal values.

That is, the protrusion structure formed on the back surface 34b of the outer lens 30 is also an aggregate of concave recesses. Therefore, as shown in FIG. 8, the water vapor attracted to the back surface 34b of the outer lens 30 adheres to the dent portion and the plane between the dent portions and grows, and the adhered water vapor grows individually without being collected. It becomes water vapor Wt. However, since the dimension of the plane between the recess and the recess is less than half the wavelength of visible light, it is possible to prevent water vapor from growing beyond the dimension of the plane between the recess and the recess to become water droplets. .. Therefore, it becomes easy to keep the water droplet in a size of half a wavelength or less of visible light. Further, the water vapor adhering to the protrusion 35 and the water vapor adhering to the recessed portion between the protrusions 35 do not gather and grow individually to form water droplets Wt.

Then, the grown water droplet Wt is held at the position of the protrusion 35 or the position of the recessed portion at a contact angle larger than the contact angle of the water droplet on the flat surface where the protrusion 35 does not exist due to the action of surface tension. That is, when there are a large number of protrusions 35 on the back surface 34b of the outer lens 30, it is difficult for the water droplets Wt to collect together as compared with the case where the back surface 34b of the outer lens 30 is a flat surface, and a large number of water droplets Wt are held in a relatively small size. NS. Here, as described above, since the size of the protrusion 35 is less than half the wavelength of visible light, the size of the water droplet Wt adhering to the protrusion 35 is also less than half the wavelength of the visible light and is invisible to humans. .. That is, since the water droplet Wt is invisible to humans, it is not recognized that the outer lens 30 (lens body 34) has become cloudy. Further, since the protrusion 35 does not change with time, it is possible to prevent fogging of the lens body 34 of the outer lens 30 for a long period of time.

<Advantages of the headlamp unit 20 according to this embodiment>
According to the headlamp unit 20 according to the present embodiment, a large number of protrusions (150 nm to 200 nm) having a size of half a wavelength or less of visible light are formed on the back surface of the outer lens 30 (transparent portion) at predetermined intervals. Therefore, the water vapor attracted to the back surface of the outer lens 30 adheres to the protrusion 35 and the recessed portion between the protrusions 35 and grows. Therefore, it is difficult for the water droplets Wt to gather together, and a large number of water droplets Wt are held in a relatively small size. Here, since the size of the protrusion 35 is less than half the wavelength of visible light, the water droplet Wt adhering to the protrusion 35 is also invisible to humans. In this way, since the water droplet Wt is invisible to humans, it is not recognized that the outer lens 30 (lens body 34) has become cloudy. Further, since the protrusion 35 does not change with time, it is possible to prevent fogging on the inner surface of the outer lens 30 for a long period of time.

Further, since the protruding dimension H of the protrusion 35, the diameter dimension W of the protrusion 35, and the dimension L between the adjacent protrusions 35 are set to substantially the same value, the grown water droplet Wt is increased by the action of surface tension. The contact angle can be maintained at the position of the protrusion 35 or the position of the recess. That is, it becomes difficult for the individually grown water droplets Wt to gather at the position of the protrusion 35 or the position of the recessed portion. Further, since the protrusion 35 of the outer lens 30 (lens body 34) can be formed by injection molding, the protrusion 35 can be easily formed. Further, the second molding surface 43f of the second molding mold 43 and the portion in the vicinity thereof are manufactured by using a copper alloy having high thermal conductivity. Therefore, the temperature control of the second molding surface 43f and the portion in the vicinity thereof at the time of injection molding becomes easy, and the material of the outer lens 30 can be reliably supplied to the recess 43z of the second molding surface 43f.

<Change example>
The present invention is not limited to the above embodiment, and changes can be made without departing from the gist of the present invention. For example, in the present embodiment, as shown in FIG. 3 and the like, an example in which a truncated cone-shaped protrusion 35 is formed on the back surface 34b of the outer lens 30 is shown. However, as shown in FIG. 9, it is also possible to form a chevron-shaped protrusion 50 in which the protruding end of the protrusion is not flat. Further, in the present embodiment, the headlamp unit 20 is illustrated as a vehicle component, but the present invention can be applied to other lamp units. In addition to the lamp unit, the present invention can also be applied to, for example, the back surface of a transparent portion that covers instruments of an instrument panel. Further, the outer lens or the like (transparent portion) of the lamp unit or the like may be colorless or colored.

20 ... Headlamp unit (vehicle parts)
30 ... Outer lens (transparent part)
34 ... Lens body 34b ... Back side 35 ... Protrusion 40 ... Injection molding 43z ... Recess 43 ... Second molding 43f ... Second molding surface ( Molding surface)
Wt ... Water droplets

Claims (6)

A vehicle part with a transparent part
On the back surface of the transparent portion to which the outside air does not come into direct contact, a large number of protrusions having a size of half a wavelength or less of visible light are formed at predetermined intervals.
The protruding dimension and the diameter dimension of the protrusion are set to 150 nm to 400 nm.
The gap size of the protrusions adjacent to each other is set to 150 nm to 400 nm.
The flatness Ra, which represents the smoothness of the protruding end face of the protrusion, is 30 nm or less.
A large number of the protrusions are independently formed vehicle parts. The vehicle part according to claim 1.
A vehicle part in which the protrusion dimension of the protrusion is 1 time or more and 3 times or less the gap size of the protrusions adjacent to each other. The vehicle part according to claim 1 or 2.
A vehicle component in which the contact angle is set to 60 ° to 100 ° when the back surface of the transparent portion on which the protrusion is formed is flat. The vehicle part according to any one of claims 1 to 3.
The material of the transparent part is a vehicle part which is a plastic material. A large number of protrusions having a size of half a wavelength or less of visible light are formed at predetermined intervals on the back surface of the transparent portion which is provided with a transparent portion and is not in direct contact with the outside air .
The protruding dimension and the diameter dimension of the protrusion are set to 150 nm to 400 nm.
The gap size of the protrusions adjacent to each other is set to 150 nm to 400 nm.
The flatness Ra, which represents the smoothness of the protruding end face of the protrusion, is 30 nm or less.
A large number of the protrusions are independently formed methods for manufacturing vehicle parts.
A step of molding the molding surface for molding the back surface of the transparent portion in an injection molding die by using a reactive ion etching method (Reactive Ion Etching).
A step of injection molding the transparent portion using the injection molding die provided with the molding surface, and
Manufacturing method of vehicle parts having. The method for manufacturing a vehicle part according to claim 5.
A method for manufacturing a vehicle part in which the molding surface of the injection molding die is made of a copper alloy.

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