JP2021028162A - Anti-fingerprint structure - Google Patents

Abstract

To provide an anti-fingerprint structure capable of preventing sebum from remaining when a finger comes into contact with it.SOLUTION: An anti-fingerprint structure of the present invention is formed by laminating a porous layer, a modified layer, and an oil layer containing a fluorine-based oil in this order on a base material. Then, the modified layer is formed by bonding a bonding portion of a perfluoropolyether-based modifier to the porous layer, with a fluorine content of the modified layer as 38 to 60 mol%, and the fluorine-based oil satisfies the following formula (1), to transfer the fluorine-based oil in a part that came into contact with a finger to a finger (sebum) side. Therefore, it is possible to prevent sebum from remaining on a surface of the anti-fingerprint structure. Surface free energy [mJ/m2]×kinematic viscosity [cSt]≤700 ... Equation (1).SELECTED DRAWING: None

Description

The present invention relates to an anti-fingerprint structure, and more particularly to an anti-fingerprint structure that suppresses residual attached sebum.

Fingerprints on the surface of an article can make the article appear dirty and give an unpleasant impression.

According to the international publication 2013/008345 of Patent Document 1, the coating film having fine irregularities and containing a fluorine-containing compound has a small amount of sebum adhering to the coating film, and the sebum remaining adhering to the coating film is present. It is disclosed that dirt can be made inconspicuous because it is finely dispersed without agglomeration.

International release 2013/008645

However, in order to prevent the residual sebum that comes into contact with the surface of the article, the surface of the article must have super oil repellency (contact angle of sebum ≥ 150 degrees), and depending on the surface modification with a fluorine compound, it is super oil repellent. Is not possible, so sebum that inevitably adheres to the surface of the article remains.

Further, even if the fingerprints are made inconspicuous by preventing the aggregation of sebum remaining on the surface of the article, the sebum remains and accumulates on the surface of the article. Therefore, by making the dirt inconspicuous, the article may be made inconspicuous. Cannot prevent dirt.

The present invention has been made in view of the problems of the prior art, and an object of the present invention is to provide an anti-fingerprint structure capable of preventing residual contact of sebum.

As a result of diligent studies to achieve the above object, the present inventor divides the fluorine-based oil on the surface of the anti-fingerprint structure and contacts the finger when the finger (sebum) in contact with the anti-fingerprint structure separates. It has been found that the above object can be achieved by migrating the fluorine-based oil in the portion to the finger side together with the inevitably attached sebum, and the present invention has been completed.

That is, the fingerprint-proof structure of the present invention is formed by laminating a porous layer, a modified layer, and an oil layer containing a fluorine-based oil in this order on a base material.
Then, the modified layer is formed by bonding the bonding portion of the perfluoropolyether-based modifier to the porous layer.
The fluorine content of the modified layer is 38 to 60 mol%.
The above-mentioned fluorine-based oil satisfies the following formula (1);

Surface free energy [mJ / m ² ] x kinematic viscosity [cSt] ≤700 ・ ・ ・ Equation (1)

According to the present invention, since the fluorine-based oil in the portion in contact with the finger is transferred to the finger (sebum) side, it is possible to prevent the sebum inevitably adhering to the surface of the anti-fingerprint structure from remaining.

The anti-fingerprint structure of the present invention will be described in detail.
The fingerprint-proof structure is formed by laminating a porous layer, a modified layer, and an oil layer containing a fluorine-based oil in this order on a base material.

<Modified layer>
The modified layer is formed by binding the bonding portion of the perfluoropolyether-based modifier to the porous layer.

The modified layer reduces the surface energy of the porous layer, spreads the fluorine-based oil on the surface of the porous layer, and forms a smooth surface (oil layer) of the fluorine-based oil on the surface of the anti-fingerprint structure. ..

The modified layer of the present invention has a fluorine content of 38 to 60 mol%, and more preferably 44 mol% or more.

In the anti-fingerprint structure of the present invention, the modified layer has a fluorine content of 38 to 60 mol%, and the surface of the porous layer is covered with fluorine, which is a perfluoropolyether-based modifier. Even when the oil layer is pushed away and the finger (sebum) reaches the porous layer, the modified layer can repel the sebum.
Therefore, the sebum does not adhere to the porous layer through the modification defect and is not pinned, so that the sebum in contact with the anti-fingerprint structure does not remain.

In the modified layer, it is preferable that the perfluoropolyether-based modifier bonded to the porous layer satisfies the following formula (2).

X / (X + Y) ≤ 0.20 or less ... Equation (2)

However, in equation (2),
X represents the total content [mol%] of the (-OR) bond and the (-CH _2- CH _{2-) bond of the alkoxysilane portion of the perfluoropolyether-based modifier.
Y is the total content of (-CF 2-} ) bond, (CF _2- O-) bond and (-CF ₃ ) bond of the perfluoropolyether main chain of the perfluoropolyether-based modifier [mol%]. ] Is represented.

As the perfluoropolyether-based modifier, a conventionally known fluorine-based silane coupling agent can be used, and specific examples thereof include perfluoropolyether-containing ethoxysilane.

The perfluoropolyether-based modifier has a perfluoropolyether main chain portion and an alkoxysilane portion having a plurality of alkoxy groups.
The perfluoropolyether-containing ethoxysilane is represented by the structural formula (1).

但し、構造式（１）中Ｒは、メトキシ基又はエトキシ基を表わし、ｎは整数を表わす。

However, in the structural formula (1), R represents a methoxy group or an ethoxy group, and n represents an integer.

In such a modifier, the alkoxy group (-OR) in the alkoxysilane portion is hydrolyzed to generate a silanol group (Si-OH), and this silanol group is dehydrated and condensed with a hydroxyl group on the surface of the porous layer to perfluoro. A modified layer is formed by binding the polyether modifier to the surface of the porous layer.

In the modifier bonded to the porous layer, the alkoxy group in the alkoxysilane portion is used for the bond to reduce the (-OR) bond, so that the (-OR) bond of the alkoxysilane portion in the modified layer and ( -CH ₂ -CH ₂ -) binding the total content of, i.e., X in formula (2) decreases.

Further, when Y in the formula (2) becomes large, the bulk of the perfluoropolyether main chain portion increases, and the range in which one molecule of the perfluoropolyether-based modifier can modify the porous layer becomes wide. , The above formula (2) is an index of modification defects.

That is, when X / (X + Y) ≦ 0.20 or less in the formula (2), it means that there are very few modification defects. The X / (X + Y) is more preferably 0.18 or less.

The perfluoropolyether-based modifier preferably has a Y of 18 to 25 [mol%]. If the main chain of the perfluoropolyether is too short, it may be difficult to obtain a sufficient modification effect. In addition, if the main chain of perfluoropolyether is too long, the entanglement with the molecules of the fluorine-based oil, which will be described later, becomes stronger, and the fluorine-based oil is strongly retained, so that the fluorine-based oil is on the finger side (skin oil side). It may be difficult to move to.

The alkoxysilane of (-OR) binding and _(-CH 2 -CH ₂ -) the total content of bound [mol%], perfluoropolyether main chain portion of the (-CF ₂ -) combined with (CF ₂ - The total content [mol%] of O-) bond and (-CF ₃ ) bond can be measured by X-ray photoelectron spectroscopy (hereinafter referred to as XPS analysis).

In the present invention, the elemental composition of the surface was measured under the following devices and conditions, and the ratio (mol%) of the number of fluorine atoms among the detected elements was measured. _{In addition, the proportions of -CF 2} -bond, -CF _2- O- bond, -CF ₃ bond, -CO bond, and- (CH ₂ ) n- bond on the sample surface were measured for carbon atom C1s.
Device name: X-ray photoelectron spectroscopy analyzer PHI Quantum-2000
X-ray source: Monochromated Al Kα ray (1486.6 eV) 40W
Photoelectron extraction angle: 45 ° (Measurement depth: Approximately 4 nm)
Measurement area: 200 μmφ
Sample pretreatment: The sample was processed to an appropriate size and measured.

In the modified layer of the present invention, the surface of the porous layer is washed by irradiating the porous layer with an ion beam in a clean vapor deposition tank, and the surface of the porous layer is excessive with respect to the OH groups on the surface of the porous layer in the vapor deposition tank. It can be formed by depositing a perfluoropolyether-based modifier of.

There are many contaminants such as hydrocarbons in the air, and even if the surface of the porous layer is washed outside the vapor deposition tank, the contaminants will adhere before they are put into the vapor deposition tank, and the adhered contamination will cause perfluoropolyether. The binding of the system modifier is inhibited and a modification defect occurs.

In the present invention, the surface of the porous layer is washed by irradiating the porous layer in the clean thin-film deposition tank with an ion beam, and the porous layer is excessively charged without leaving the vapor deposition tank. Since the perfluoropolyether-based modifier is vapor-deposited, the occurrence of modification defects can be significantly reduced.

_{Further, it is preferable that SiO 2} is vapor-deposited on the porous layer washed in a clean thin-film deposition tank, and then a perfluoropolyether-based modifier is vapor-deposited.

_{By vapor-depositing SiO 2} before depositing the perfluoropolyether-based modifier, _{OH groups derived from SiO 2} are formed on the surface of the porous layer, and the OH groups form the perfluoropolyether-based modifier. Is more likely to bond to the porous layer, and the occurrence of modification defects can be prevented.

By applying heat treatment, the modified layer is fixed on the surface of the perfluoropolyether-based modifier porous layer, and even when the finger (sebum) reaches the porous layer, modification defects occur. Can be suppressed. The heating temperature depends on the modifier, but is preferably 120 to 180 ° C.

<Oil layer>
The oil layer of the anti-fingerprint structure of the present invention contains a fluorine-based oil.
The fluorine-based oil satisfies the following formula (1).

Surface free energy [mJ / m ² ] x kinematic viscosity [cSt] ≤700 ・ ・ ・ Equation (1)

The fluorine-based oil satisfying the above formula (1) has high repellent resistance to sebum, low kinematic viscosity (20 ° C.), and low cohesive force between molecules. Therefore, when the finger touching the anti-fingerprint structure is separated, the finger The fluorinated oil is divided at the part where it comes into contact with the finger, and the fluorinated oil slightly shifts to the finger side. Therefore, the sebum that has come into contact with the anti-fingerprint structure does not remain on the anti-fingerprint structure side.

On the other hand, a fluorine-based oil that does not satisfy the above formula (1) inevitably adheres to the surface of the fluorine-based oil because it has a large cohesive force and is difficult to transfer to the finger side even if it has a repellent property against sebum. Sebum is likely to remain on the surface.

The 20 ° C. kinematic viscosity can be measured using a glass capillary viscometer according to JIS K2283: 2000.
As described in this JIS standard, the method of calculating the kinematic viscosity by the glass capillary viscometer can be expressed by the following formula using the characteristic items of the viscometer.

なお，式中のＥはガラス製毛管式粘度計毎に規定された値を用いる。

For E in the formula, the value specified for each glass capillary viscometer is used.

It is preferable that the fluorine-based oil further satisfies the following formula (3).

Surface free energy [mJ / m ² ] x kinematic viscosity [cSt] ≤ 450 ... Equation (3)

In the fluorine-based oil having a low kinematic viscosity (20 ° C.) that satisfies the formula (3), the fluorine-based oil in the portion in contact with the finger is more easily divided, and the inevitably attached sebum remains on the surface of the fingerprint-proof structure. Can be prevented.

The surface free energy (25 ° C.) of the fluorine-based oil is preferably ^{16.6 to 23 [mJ / m 2].} If the surface free energy of the fluorine oil is too low, the weight loss due to evaporation becomes large, and sufficient heat resistance cannot be obtained. The surface energy of sebum is ^{about 30 [mJ / m 2} ], and if the surface free energy of fluorine oil becomes too high, sebum may easily remain on the fluorine oil.

The surface free energy of a liquid such as fluorine-based oil is measured by various methods, and a simple method is a suspension method. When a liquid is pushed out from the tip of a vertically downward thin tube, droplets hang from the tip of the thin tube. These hanging droplets are called "suspended droplets". Since the shape of the suspension depends on the amount, density, and surface free energy of the hanging liquid, the surface free energy can be obtained by analyzing the shape of the suspension. In the case of fluorine-based oil, the surface free energy is small, so it is difficult to maintain the hanging "suspended" state, and it may be difficult to measure. In that case, if the tip of the vertically downward thin tube is immersed in a liquid such as water, it is relatively easy to maintain the "suspended" state, and it is easy to measure. Further, there are several methods in the suspension method depending on the analysis method of the suspension shape. For example, the maximum diameter de of the suspension and the suspension diameter ds at a position above the lowermost end of the suspension by de. The ds / de method for actually measuring and calculating the surface tension can be applied.

Perfluoropolyether oil can be used as the fluorine-based oil. Since the perfluoropolyether oil has a perfluoropolyether chain like the above-mentioned modifier, it has a high affinity with the above-mentioned modified layer, and the depletion of the fluorine-based oil is suppressed.

The average molecular weight of the fluorine-based oil is not particularly limited as long as it satisfies the above formula (1), but is preferably 1500 to 4000, and more preferably 2000 to 3500.

If the average molecular weight is too small, the entanglement with the modifier molecule is small and it may be easily worn, and if the average molecular weight is too large, the entanglement with the modifier molecule becomes large and shifts to the finger side. It can be difficult.

The structure of the fluorine-based oil may be either a linear type having no side chain or a side chain type having a side chain, but a side chain type fluorine-based oil is preferable.

The linear type fluorine-based oil has a larger van der Waals force than the side chain type, and the binding force of the modifier with the perfluoropolyether main chain portion is increased, making it difficult to transfer to the finger side. Sometimes.

Examples of the side chain type fluorine-based oil include Crytox 100 to 102 manufactured by DuPont, and examples of the linear type fluorine-based oil include Fomblin M03 manufactured by Solvay. it can.

When the fluorine-based oil is left at 120 ° C. for 24 hours, the evaporation loss of the fluorine-based oil is preferably 35% by mass or less. If the evaporation weight loss exceeds 35% by mass, the durability of the anti-fingerprint structure may easily decrease.

The oil layer can be formed by applying the fluorine-based oil to the porous layer on which the modified layer is formed and wiping off the excess fluorine-based oil.

<Porous layer>
The porous layer is a so-called sponge-like structure in which a plurality of pores communicate with each other and are randomly arranged three-dimensionally, and holds the fluorine-based oil in and / or on the surface of the pores.

The porous layer is preferably made of a metal oxide mainly composed of silicon oxide.
Since the porous layer is a metal oxide containing silicon oxide having high hardness, the sliding resistance is improved and the durability of the anti-fingerprint structure is improved.

Examples of the metal oxide constituting the porous layer include quartz glass, soda glass, borosilicate glass and the like containing 60 wt% or more of _{silicon oxide (SiO 2).}

The average film thickness (h) of the porous layer is preferably 50 to 1000 nm. When the average film thickness of the porous layer is 50 nm or more, the fluorine-based oil can be sufficiently retained, and the durability of the anti-fingerprint structure is improved.
Further, when it is 1000 nm or less, it is possible to prevent the occurrence of cracks due to volume shrinkage or the like during the production of the porous layer.

The porous layer can be formed by a conventionally known method, and examples of the method for forming the porous layer include a sol-gel method and the like.

<Base material>
The base material is not particularly limited as long as a porous layer can be formed, and for example, an inorganic base material such as a steel plate or glass or an organic base material such as a resin or a coating film can be used.

The anti-fingerprint structure of the present invention includes automobile parts such as rear-view mirrors, room mirrors, liquid crystal screens for car navigation systems, meter panels, etc., whose visibility is reduced by fingerprints, as well as instrument panels, consoles, door knobs, etc. It can also be suitably used for automobile parts whose design is deteriorated.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following Examples.

[Example 1]
(Preparation of porous layer)
Solution A was prepared by mixing 1.16 g of pure water, 1.50 g of TEG (triethylene glycol), 0.78 g of IPA (isopropyl alcohol), and 0.30 g of concentrated sulfuric acid in this order.
Further, _{8.04 g of Si 5} O ₄ (OEt) ₁₂ (ethyl silicate 40 manufactured by Corcote) and 0.78 g of IPA (isopropyl alcohol) were mixed in this order to prepare Solution B.

Solution B is added while stirring solution A with a magnetic stirrer at 1500 rpm, and after the temperature rise has stopped, IPA is added so that it is diluted 5 times, and then stirred at 1500 rpm for 1 minute. A coating solution was obtained.

The coating liquid was spin-coated on a soda lime glass plate (5 cm x 10 cm x 1.8 mm thick) treated with atmospheric pressure plasma under the following conditions, and then immediately taken out from the spinner and allowed to stand on a flat surface for 2 minutes and air-dried. did.
Spin coating conditions The dropping amount of the coating liquid was set to 1500 [μL], and the coating solution was applied at 100 rpm for 3 seconds, further at 500 rpm for 5 seconds, and at 1000 rpm for 15 seconds.

(Baking)
After leaving it in a dryer at 150 ° C. for 1 hour for temporary firing, it was taken out from the dryer and left to room temperature. Further, put it in a muffle furnace at room temperature, raise the temperature to 500 ° C. over 30 to 45 minutes, hold it for a while, stop heating, slowly cool it to 150 ° C. in the muffle furnace, take it out, and leave it to room temperature to make it porous. A layer was formed.

(Modified layer)
The substrate on which the porous layer was formed was placed in a clean vapor deposition tank, and the porous layer was irradiated with an ion beam to clean the surface of the porous layer. Subsequently, a pretreatment for vapor deposition of SiO _{2 was performed in the vapor deposition tank.} An excess perfluoropolyether-based modifier (DAIKIN Optool DSX) was vapor-deposited on the porous layer on which _{SiO 2 was vapor-deposited to form a modified layer having a film thickness of 7 nm.}

(Oil layer)
Fluorine-based oil (Dupont: Krytox101, molecular weight: 1780, surface free energy: 16.6 [mJ / m ² ], kinematic viscosity: 17.4 [cSt]) is added to the modified layer to add excess fluorine oil. Was wiped off to obtain a fingerprint-proof structure having a retention amount of fluorooil of 0.0011 [g].

[Example 2]
An anti-fingerprint structure is obtained in the same manner as in Example 1 except that an excess perfluoropolyether-based modifier is vapor-deposited to form a modified layer having a film thickness of 15 nm without performing a pretreatment for vapor-depositing SiO _2. It was.

[Example 3]
Anti-fingerprint in the same manner as in Example 1 except that the fluorine-based oil is replaced with DuPont: Krytox102 (molecular weight: 2190, surface free energy: 16.8 [mJ / m ^{2], kinematic viscosity: 38 [cSt]).} Obtained a structure.

[Example 4]
Example 1 except that the fluorine-based oil is replaced with a low molecular weight component fractionated product (molecular weight: 3200, surface free energy: 23 [mJ / m ² ], kinematic viscosity: 19 [cSt]) manufactured by Solvay S.A. The anti-fingerprint structure was obtained in the same manner.

[Example 5]
Anti-fingerprint structure in the same manner as in Example 1 except that the fluorine-based oil is replaced with Solvay: Fomblin M03 (molecular weight: 3900, surface free energy: 23 [mJ / m ^{2], kinematic viscosity: 30 [cSt]).} Got

[Example 6]
Anti-fingerprint in the same manner as in Example 1 except that the fluorine-based oil is replaced with DuPont: Krytox100 (molecular weight: 1550, surface free energy: 16.4 [mJ / m ^{2], kinematic viscosity: 12 [cSt]).} Obtained a structure.

[Example 7]
(Preparation of porous layer)
Solution A was prepared by mixing 0.52 g of pure water and 0.48 g of 1N hydrochloric acid.
Further, 0.93 g of tetrabutyl orthotitanate (Tetrabutyl Orthotitanate manufactured by Tokyo Chemical Industry Co., Ltd.) and 14.42 g of ethanol were mixed to prepare Solution B.

Solution B was added while stirring the solution A at 1500 rpm with a magnetic stirrer, and the mixture was stirred for 30 minutes after the temperature stopped rising to obtain a coating liquid.

An anti-fingerprint structure was obtained in the same manner as in Example 2 except that the porous layer was formed by using the above coating liquid.

[Example 8]
An anti-fingerprint structure was obtained in the same manner as in Example 1 except that a modified layer having a film thickness of 10 nm was formed.

[Example 9]
After forming the modified layer having a film thickness of 10 nm, an anti-fingerprint structure was obtained in the same manner as in Example 7 except that the modified layer was heated at 150 ° C. for 30 minutes.

[Example 10]
After forming the modified layer having a film thickness of 7 nm, an anti-fingerprint structure was obtained in the same manner as in Example 1 except that the modified layer was heated at 150 ° C. for 30 minutes.

[Example 11]
After forming the modified layer having a film thickness of 5 nm, an anti-fingerprint structure was obtained in the same manner as in Example 1 except that the modified layer was heated at 150 ° C. for 30 minutes.

[Comparative Example 1]
The surface of the porous layer is plasma-cleaned, and a perfluoropolyether-based modifier (DAIKIN Optool DSX) is spray-coated to form a modified layer having a film thickness of 30 nm, in the same manner as in Example 2. An anti-fingerprint structure was obtained.

[Comparative Example 2]
A fingerprint-proof structure was obtained in the same manner as in Comparative Example 1 except that a modified layer having a film thickness of 30 nm was formed by dip-coating with a perfluoropolyether-based modifier (Fluorosurf FG-5020TH).

[Comparative Example 3]
Anti-fingerprint in the same manner as in Example 1 except that the fluorine-based oil is replaced with DuPont: Krytox103 (molecular weight: 2660, surface free energy: 17.3 [mJ / m ^{2], kinematic viscosity: 82 [cSt]).} Obtained a structure.

[Comparative Example 4]
Anti-fingerprint in the same manner as in Example 1 except that the fluorine-based oil is replaced with DuPont: Krytox 104 (molecular weight: 3480, surface free energy: 18.3 [mJ / m ^{2], kinematic viscosity: 177 [cSt]).} Obtained a structure.

[Comparative Example 5]
A conical unevenness having a pitch of 100 nm and a height of 10 nm was formed on the surface of the triacetyl cellulose film by a nanoimprint method to form a porous layer. The surface of this porous layer was plasma-cleaned and spray-coated with a perfluoropolyether-based modifier (DAIKIN Optool DSX) to form a modified layer having a film thickness of 30 nm to obtain an anti-fingerprint structure.

Table 1 shows the configurations of the anti-fingerprint structures of Examples 1 to 11 and Comparative Examples 1 to 5.

<Evaluation>
A simulated fingerprint was attached to the anti-fingerprint structure of Examples 1 to 11 and Comparative Examples 1 to 5 and evaluated by the following method. Table 2 shows the evaluation results together with the XPS analysis results of the modified layer.

[Adhesion of simulated fingerprint]
Adhesion of the simulated fingerprint to the anti-fingerprint structure is as follows: (1) preparation of simulated fingerprint liquid, (2) preparation of simulated fingerprint sheet, (3) transfer of simulated fingerprint liquid to silicone rubber, (4) molding of simulated fingerprint. It was carried out in 4 steps of adhesion to the material surface.

(1) Preparation of simulated fingerprint solution The following materials were weighed at the following ratios and then stirred with a magnetic stirrer for 30 minutes to obtain a simulated fingerprint solution.

14 parts by mass of oleic acid Silica particles (number average particle size 2 μm) 6 parts by mass Isopropyl alcohol 80 parts by mass

The number average particle size of the silica particles is such that the silica particles are mixed with a dispersion medium (isopropyl alcohol) at a solid content concentration of 5% by mass, dispersed by ultrasonic waves, and then dropped onto a conductive tape to prepare an observation sample. I asked for it.

(2) Preparation of simulated fingerprint sheet Wire the simulated fingerprint solution to "Lumirror" (registered trademark) U46 (manufactured by Toray Industries, Inc.) in which an easily adhesive paint is applied on a PET resin film as a supporting base material. It was coated with a bar (# 7) and dried at 50 ° C. for 2 minutes to obtain a simulated fingerprint sheet.

(3) Transfer of simulated fingerprint to silicone rubber JIS K6253: 1997 silicone rubber having a rubber hardness of 50 was polished to a surface roughness of JIS B0601: 2001 with # 250 water resistant paper to Ra = 3 μm.
Next, the silicone rubber polished with the water resistant paper was pressed against the simulated fingerprint sheet at a pressure of 30 KPa.

Adhesion amount of simulated fingerprint liquid was ^{0.9g / m 2 ~1.1g / m 2} .
The amount of the simulated fingerprint liquid attached to the silicone rubber (g / m ² ) was determined from the area of the silicone rubber and the mass difference before and after the adhesion.

(4) Adhesion of simulated fingerprint to the anti-fingerprint structure The silicone rubber to which the simulated fingerprint liquid is transferred is pressed against the surface of the anti-fingerprint structure at 30 KPa, and the trace formed on the surface of the anti-fingerprint structure is referred to as the simulated fingerprint. did.

[Color of diffuse reflected light of fingerprint ΔE ^* ]
A black vinyl tape is attached to the surface (base material side) of the anti-fingerprint structure opposite to the oil layer, and the anti-fingerprint structure before the simulated fingerprint is attached and the anti-fingerprint structure to which the simulated fingerprint is attached are diffused. The reflected color of light was measured using a spectrophotometer CM-3600A manufactured by Konica Minolta Co., Ltd. based on JIS Z8722: 2009 under the condition of Sb10W10 using a specular reflected light trap (de: 8 °), and a fingerprint. ^{The color difference ΔE *} before and after the adhesion was determined.

[Sensory evaluation]
Each anti-fingerprint structure to which the simulated fingerprint was attached was fixed on the navigation LCD screen of the car in fine weather, and the ease of concern was evaluated from the average score of the evaluations of multiple panelists seated in the driver's seat.

"I don't care at all" is 5 points, "I don't care much" is 4 points, "I don't care much" is 3 points, "I'm a little worried" is 2 points, and "Very worrisome" is 1 point. did.

Average score is 4 points or more: ◎
Average score is 3 points or more and less than 4 points: ○
Average score is 2 points or more and less than 3 points: △
Average score is less than 2 points: ×

From the above evaluation results, it can be seen that in Examples 1 to 11 in which the fluorine content of the modified layer satisfies 38 to 60 mol% and the formula (1) is provided, fingerprint residue is suppressed and fingerprint stains are not a concern. ..
Further, from the comparison between Example 1 and Example 2, when SiO ₂ vapor deposition (pretreatment) is performed, the occurrence of modification defects is suppressed, and even when pressed, sebum is not pinned to the porous layer and fingerprints are formed. It can be seen that the residue of is suppressed.
Furthermore, Example 4 using the side-chain type fluorine-based oil has a larger molecular weight than the fluorine-based oils of Examples 1 to 3, but fingerprint residue is suppressed. Therefore, the fluorine-based oil is used. It can be seen that when is a side chain type, it easily shifts to the finger side and the fingerprint residue is suppressed.
In Example 6, the residue of fingerprints could be suppressed, but the amount of evaporation was large and the durability was lowered as compared with other examples.
In addition, in Examples 9 to 11 which were heat-treated after forming the modified layer, the occurrence of modification defects was suppressed even when the modifier was fixed on the porous surface and the finger (sebum) reached the porous layer. It can be seen that the occurrence of fingerprint stains is prevented.
From the comparison between Examples 1 and 8 and the comparison between Examples 9 to 11, it can be seen that the thicker the film thickness of the modified layer, the higher the fluorine content. This is because the excess film-forming modifier contains functional groups such as silanol that are not bonded to the base material in the film, which makes it difficult for the film itself to be uniformly formed, and the fluorine content is rather low. It is presumed that it will be.

Claims (7)

A porous layer, a modified layer, and an oil layer containing a fluorine-based oil are laminated in this order on the base material.
The modified layer is formed by bonding the bonding portion of the perfluoropolyether-based modifier to the porous layer.
The fluorine content of the modified layer is 38 to 60 mol%.
A fingerprint-proof structure in which the above-mentioned fluorine-based oil satisfies the following formula (1).

Surface free energy [mJ / m ² ] x kinematic viscosity [cSt] ≤700 ・ ・ ・ Equation (1)
The anti-fingerprint structure according to claim 1, wherein the modified layer has a fluorine content of 44 to 60 mol%. The anti-fingerprint structure according to claim 1 or 2, wherein the fluorine-based oil satisfies the following formula (3).

Surface free energy [mJ / m ² ] x kinematic viscosity [cSt] ≤ 450 ... Equation (3)
The anti-fingerprint structure according to any one of claims 1 to 3, wherein the fluorine-based oil has an evaporation loss of 35% by mass or less when left at 120 ° C. for 24 hours. The anti-fingerprint structure according to any one of claims 1 to 4, wherein the fluorine-based oil is a perfluoropolyether oil. The anti-fingerprint structure according to any one of claims 1 to 5, wherein the porous layer is made of a metal oxide. An automobile part having the anti-fingerprint structure according to any one of claims 1 to 6.