WO2022163472A1 - Sensor cover and sensor - Google Patents

Abstract

The present invention provides a sensor cover and a sensor that have excellent bug stain removal properties and scratch resistance properties, have excellent bug stain removal properties after performing a scratch test, and suppress the generation of curling. This sensor cover has a base material and an antifouling layer. The percentage of fluorine atoms on the surface of the antifouling layer opposite the base material side is 20 atomic% or more. The percentages of fluorine atoms is 20 atomic% or more at each of a 50 nm depth position, a 100 nm depth position, a 150 nm depth position, a 200 nm depth position, and a 250 nm depth position, from the surface of the antifouling layer opposite the base material side, and along the thickness direction. The thickness of the antifouling layer is 500 nm to 20 μm.

Description

sensor cover, sensor

The present invention relates to sensor covers and sensors.

In order to realize driving support technology for vehicles such as automobiles and motorcycles, it is necessary to mount a sensor on the vehicle body for detecting information outside the vehicle. Such sensors include, for example, LiDAR (Light Detection and Ranging) systems.
Since there is a risk that the detection performance of the sensors described above may be degraded by various types of contamination, a sensor cover that protects the light-emitting element such as a laser is often placed in front of the light-emitting element.
Such a sensor cover is required to have excellent scratch resistance. For example, Patent Document 1 discloses a composition for forming a hard coat layer capable of forming a hard coat layer having excellent scratch resistance.

Patent No. 5651921

On the other hand, considering the application to vehicles and the like, it is desired that the sensor cover can be easily removed from insect stains. In other words, insects collide with the head of a vehicle moving at high speed, where the sensor is located, and "insect stains" are likely to occur. Therefore, it is demanded that this insect stain be easily removed. In other words, it is required to be excellent in insect stain removability.
In addition, when the vehicle moves at high speed, the sensor cover may be hit by a stone or the like, and there is a demand for the sensor cover to be excellent in removing insect stains even after going through such a situation. Therefore, even after the sensor cover is subjected to the abrasion test, it is required to have excellent insect stain removability.
The present inventors investigated the properties of the substrate having the hard coat layer described in Patent Document 1, and found that the hard coat layer had insufficient insect stain removability after being subjected to a scratch test. found that further improvements were needed.

In addition to the above-mentioned insect stain removability, the sensor cover is required to have scratch resistance as described above, and it is also required that the sensor cover does not curl when left standing in a predetermined environment.

In view of the above circumstances, the present invention provides a sensor cover that is excellent in insect stain removability and scratch resistance, is also excellent in insect stain removability after conducting a scratch test, and further suppresses curling. The task is to provide
Another object of the present invention is to provide a sensor.

The inventors have found that the above problems can be solved by the following configuration.

(1) A sensor cover having a substrate and an antifouling layer,
The ratio of fluorine atoms on the surface of the antifouling layer opposite to the base material is 20 atomic% or more,
50 nm depth position, 100 nm depth position, 150 nm depth position, 200 nm depth position, and 250 nm depth along the thickness direction from the surface of the antifouling layer opposite to the substrate side. The ratio of fluorine atoms at each position of the position is 20 atomic% or more,
A sensor cover, wherein the antifouling layer has a thickness of 500 nm to 20 μm.
(2) A sensor cover having a substrate and an antifouling layer,
The surface of the antifouling layer opposite to the substrate has a contact angle of 70° or more with respect to water and a contact angle of 40° or more with respect to methylene iodide,
50 nm depth position, 100 nm depth position, 150 nm depth position, 200 nm depth position, and 250 nm depth along the thickness direction from the surface of the antifouling layer opposite to the substrate side. The contact angle to water at each position of the position is 70 ° or more, and the contact angle to methylene iodide is 40 ° or more,
A sensor cover, wherein the antifouling layer has a thickness of 500 nm to 20 μm.
(3) The sensor cover according to (1) or (2), wherein the antifouling layer contains a fluorine-containing resin having a repeating unit derived from a fluorine-containing monomer.
(4) The sensor cover according to (3), wherein the fluorine-containing monomer has a polymerizable unsaturated group.
(5) The sensor cover according to (3) or (4), wherein the fluorine-containing monomer has 3 to 6 polymerizable unsaturated groups.
(6) The sensor cover according to any one of (3) to (5), wherein the fluorine atom content in the fluorine-containing monomer is 38.0 to 50.0% by mass.
(7) The sensor cover according to any one of (3) to (6), wherein the fluorine-containing resin has repeating units derived from a polyfunctional monomer having no fluorine atoms and having three or more polymerizable unsaturated groups. .
(8) The sensor cover according to any one of (1) to (7), wherein the antifouling layer contains inorganic particles.
(9) The sensor cover according to (8), wherein the inorganic particles are silica particles.
(10) A sensor comprising the sensor cover according to any one of (1) to (9).

According to the present invention, it is possible to provide a sensor cover that is excellent in insect stain removability and scratch resistance, is also excellent in insect stain removability after conducting a scratch test, and further suppresses curling.
A sensor can also be provided according to the present invention.

It is a schematic diagram which shows an example of 1st Embodiment of a sensor cover.

The present invention will be described in detail below. In this specification, the numerical range represented by "-" means a range including the numerical values described before and after "-" as lower and upper limits. First, terms used in this specification will be explained.

<<First Embodiment>>
A first embodiment of the sensor cover of the present invention is a sensor cover having a substrate and an antifouling layer, wherein the ratio of fluorine atoms on the surface of the antifouling layer opposite to the substrate is 20 atomic % or more. , along the thickness direction from the surface of the antifouling layer on the side opposite to the base material, at a depth of 50 nm, a depth of 100 nm, a depth of 150 nm, a depth of 200 nm, and The ratio of fluorine atoms at each position at a depth of 250 nm is 20 atomic % or more, and the antifouling layer has a thickness of 500 nm to 20 μm.
In the first embodiment, the ratio of fluorine atoms from the surface to the predetermined inside of the antifouling layer is within the predetermined range, so that the insect stain removability and scratch resistance, and the insect stain after the scratch test Excellent removability. Moreover, since the antifouling layer has a thickness within a predetermined range, it is excellent in scratch resistance and curl suppression.
The above embodiment will be described below with reference to the drawings. It should be noted that the figures shown below are shown in a form different in scale from actual data so that the contents of the invention can be easily understood.

A sensor cover 10 shown in FIG. 1 has a base material 12 and an antifouling layer 14 . In FIG. 1, the substrate 12 and the antifouling layer 14 are in direct contact with each other.
Each member will be described in detail below.

<Base material>
The substrate plays a role of supporting the antifouling layer.
A transparent substrate is preferable as the substrate. The transparent substrate is intended to be a substrate having a visible light and near-infrared light transmittance of 60% or more, preferably 80% or more, more preferably 90% or more.
Note that visible light refers to light of 380 to 780 nm. Near-infrared light refers to light above 780 nm and 2500 nm.

The shape of the substrate is not particularly limited, and examples thereof include a flat plate shape and a hemispherical shape.

The type of base material is not particularly limited, and known base materials can be used, including plastic base materials and glass base materials.

A polymer is preferable as the material constituting the base material.
Examples of polymer films that can be used as a substrate include cellulose acylate films (e.g., cellulose triacetate film (refractive index: 1.48), cellulose diacetate film, cellulose acetate butyrate film, and cellulose acetate propionate film). films), polyolefin films such as polyethylene and polypropylene, polyester films such as polyethylene terephthalate and polyethylene naphthalate, polyethersulfone films, polyacrylic films such as polymethyl methacrylate, polyurethane films, polycarbonate films, polysulfone films, polyether films, poly Methylpentene film, polyether ketone film, (meth)acrylonitrile film, and polymer film having an alicyclic structure (norbornene resin (Arton: trade name, manufactured by JSR, amorphous polyolefin (Zeonex: trade name) , manufactured by Zeon Corporation))).

The base material may contain various additives (for example, fine particles, plasticizers, UV inhibitors, deterioration inhibitors, release agents, etc.).

The thickness of the substrate is not particularly limited, but is preferably 10 to 5000 μm, more preferably 50 to 1000 μm.
The thickness of the base material is obtained by measuring the thickness of the base material at arbitrary 20 points with a contact-type film thickness meter (manufactured by Mitutoyo) and averaging the measured values. That is, the thickness of the substrate is the average thickness. As the contact terminal, a columnar terminal having a bottom surface of 0.5 cm in diameter is used. The measurement pressure is 0.1N.

<Anti-fouling layer>
The antifouling layer is a layer arranged on the substrate, and is preferably arranged as the outermost layer of the sensor cover.

The ratio of fluorine atoms on the surface of the antifouling layer opposite to the base material is 20 atomic % or more. More specifically, the ratio of fluorine atoms on the surface 14S of the antifouling layer 14 opposite to the substrate 12 side shown in FIG. 1 is 20 atomic % or more.
The fluorine atom ratio is preferably 30 atomic % or more, more preferably 36 atomic % or more, from the viewpoint that at least one of insect stain removability, scratch resistance, and insect stain removal after a scratch test is superior. Although the upper limit is not particularly limited, it is often 55 atomic % or less, and more often 50 atomic % or less, from the viewpoint of handleability of the materials used.
The ratio of fluorine atoms is the ratio to the total amount of carbon atoms, fluorine atoms, oxygen atoms and nitrogen atoms on the surface of the antifouling layer.
The ratio of fluorine atoms on the surface of the antifouling layer can be confirmed by analysis by X-ray photoelectron spectroscopy (XPS). Specific analysis conditions are as follows.
X-ray source: monochromatic Al-α
Measurement area: F1s, C1s, O1s, N1s
Take-off angle: 45°

In addition, along the thickness direction from the surface of the antifouling layer on the side opposite to the substrate side, the depth position of 50 nm, the depth position of 100 nm, the depth position of 150 nm, the depth position of 200 nm, and the depth position of 250 nm. The ratio of fluorine atoms at each position of the depth position is 20 atomic % or more. More specifically, as shown in FIG. 1, along the thickness direction (toward the substrate 12 side) from the surface 14S on the side opposite to the substrate 12 side of the antifouling layer 14, a depth of 50 nm A position of 100 nm is defined as a depth position D1, a position of 100 nm is defined as a depth position D2, a position of 150 nm is defined as a depth position D3, a position of 200 nm is defined as a depth position D4, and a depth of 250 nm is defined as a depth position D4. When the depth position is defined as a depth position D5, the ratio of fluorine atoms at each depth position is 20 atomic % or more.
At any of the above positions (depth position D1, depth position D2, depth position D3, depth position D4, depth position D5), the ratio of the fluorine atoms , 20 atomic % or more is preferable, and 32 atomic % or more is more preferable, because at least one of the removal of insect stains after the abrasion test is superior. Although the upper limit is not particularly limited, it is often 55 atomic % or less, and more often 50 atomic % or less, from the viewpoint of handleability of the materials used.

As a method for calculating the ratio of fluorine atoms at each depth position, first, an etching process is performed from the surface of the antifouling layer to a predetermined depth position, and when the predetermined depth position is reached, at that position A method of calculating the ratio of fluorine atoms by performing analysis by the above-mentioned X-ray photoelectron spectroscopy may be used. The conditions for X-ray photoelectron spectroscopy are the same as those described above.
Moreover, an etching process implements an Ar etching process.

The antifouling layer has a thickness of 500 nm to 20 μm, preferably 4 μm or more and less than 18 μm, more preferably 8 μm or more and less than 16 μm, from the viewpoint of the balance between scratch resistance and curl suppression.
The thickness of the antifouling layer is obtained by measuring the thickness of the entire sensor cover at 20 arbitrary positions with a contact-type film thickness meter (manufactured by Mitutoyo), and subtracting the thickness of the base material from the average value of these. Ask for it. As the contact terminal, a cylindrical terminal having a bottom surface with a diameter of 0.5 cm is used. The measurement pressure is 0.1N.
In addition, the thickness of a base material is the thickness calculated by the method mentioned above.

The material contained in the antifouling layer is not particularly limited as long as it satisfies the above-mentioned requirements, but a fluorine-containing resin having a fluorine atom can be used because it easily satisfies the predetermined requirements. A fluorine-containing resin having a repeating unit derived from a fluorine-containing monomer is particularly preferred.
The fluororesin may have repeating units derived from one type of fluoromonomer, or may have repeating units derived from two or more types of fluoromonomers.

The content of the repeating unit derived from the fluorine-containing monomer in the fluorine-containing resin is not particularly limited, but at least one of insect stain removability, scratch resistance, and insect stain removal after the scratch test is superior, so the fluorine-containing It is preferably 0.1 to 100% by mass, more preferably 5% by mass or more and less than 95% by mass, based on the total repeating units of the resin.

A fluorine-containing monomer has a polymerizable group.
The type of polymerizable group is not particularly limited, and examples thereof include a polymerizable unsaturated group, an epoxy group, an oxetane group, and the like, and a polymerizable unsaturated group is preferable from the viewpoint of reactivity.
Examples of the polymerizable unsaturated group include vinyl group, allyl group, styryl group, acryloyl group, and methacryloyl group, and from the viewpoint of reactivity, acryloyl group or methacryloyl group is more preferable.

The number of polymerizable groups (in particular, polymerizable unsaturated groups) possessed by the fluorine-containing monomer is not particularly limited, and is often 1 to 10. Two or more are preferred, three to six are more preferred, and five to six are even more preferred because at least one of the removals is superior.

The content of fluorine atoms in the fluorine-containing monomer is not particularly limited, and is often 20.0 to 60.0% by mass. From the point that one is superior, 35.0% by mass or more and less than 55.0% by mass is preferable, and 38.0 to 50.0% by mass is more preferable.

A compound represented by the formula (1) is preferable as the fluorine-containing monomer.
Formula (1) Rf−{(L) _m −Y} _n
Rf represents an n-valent group containing at least a carbon atom and a fluorine atom.
Rf may further contain at least one of an oxygen atom and a hydrogen atom.
The group represented by Rf may be chain (linear or branched) or cyclic.
The number of carbon atoms contained in Rf is not particularly limited, but is preferably 1-10, more preferably 1-6.
Rf may have an oxygen atom, is preferably an n-valent hydrocarbon group having a fluorine atom, more preferably an n-valent hydrocarbon group having a fluorine atom.

As the group represented by Rf, for example, groups represented by formulas (2) to (7) are preferable. p in formula (2) represents an integer of 1-5. In formulas (2) to (7), * represents a bonding position.

Each Y independently represents a polymerizable group. The polymerizable group is preferably a polymerizable unsaturated group, preferably a group selected from the group consisting of an acryloyl group, a methacryloyl group, an allyl group, an α-fluoroacryloyl group, and -C(O)OCH= _CH2 , An acryloyl group or a methacryloyl group is more preferred.

Each L independently represents a divalent linking group. The divalent linking group includes an alkylene group (preferably an alkylene group having 1 to 10 carbon atoms, more preferably an alkylene group having 1 to 6 carbon atoms), an arylene group (preferably an arylene group having 6 to 10 carbon atoms). , —O—, —S—, —N(R)—, or combinations thereof. Examples of the combined group include, for example, a group obtained by combining an alkylene group having 1 to 10 carbon atoms and -O-, -S- or N(R)-, an arylene group having 6 to 10 carbon atoms and -O Groups obtained by combining -, -S- or N(R)- can be mentioned. R represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.
The alkylene group and arylene group represented by L are preferably substituted with a halogen atom, preferably with a fluorine atom.
L may contain an oxygen atom and is preferably an alkylene group having a fluorine atom, and may contain an oxygen atom and is more preferably an alkylene group having 1 to 6 carbon atoms and a fluorine atom.

m represents 0 or 1;
n represents an integer of 3 or more. Of these, 3 to 10 are preferred, 3 to 6 are more preferred, and 5 to 6 are even more preferred.

Examples of fluorine-containing monomers include the following M-1 to M-16 described in paragraphs 0062 to 0065 of JP-A-2006-284761. In addition, Cf in the following structural formula represents the content (% by mass) of fluorine atoms in the compound.

The fluorine-containing resin may have repeating units other than the repeating units derived from the fluorine-containing monomer (hereinafter also simply referred to as "other repeating units").
The fluororesin may have only one type of other repeating unit, or may have two or more types of other repeating units.

The content of other repeating units in the fluororesin is not particularly limited, but at least one of the insect stain removability, scratch resistance, and insect stain removal after the scratch test is superior, so that the total amount of the fluororesin is It is preferably 1 to 99.9% by mass, more preferably 5% by mass or more and less than 95% by mass, based on the repeating unit.
In the case where the other repeating unit is a polyfunctional monomer, which will be described later, the content of the repeating unit derived from the polyfunctional monomer is set to Therefore, 30% by mass or less is preferable.

Other repeating units include three or more polymerizable unsaturated groups that do not have fluorine atoms and are excellent in at least one of insect stain removability, scratch resistance, and insect stain removal after a scratch test. A repeating unit derived from a polyfunctional monomer (hereinafter also simply referred to as "polyfunctional monomer") having a

Examples of the polymerizable unsaturated group possessed by the polyfunctional monomer include polymerizable unsaturated groups which the fluorine-containing monomer may possess.
The number of polymerizable unsaturated groups possessed by the polyfunctional monomer is 3 or more, and at least one of insect stain removability, scratch resistance, and insect stain removal after a scratch test is superior, and 3 to 6 are preferred. preferable.

The polymerizable unsaturated group possessed by the polyfunctional monomer is not particularly limited, and a group selected from the group consisting of an acryloyl group, a methacryloyl group, an allyl group, an α-fluoroacryloyl group, and -C(O)OCH= _CH2 . An acryloyl group or a methacryloyl group is more preferred.

Examples of polyfunctional monomers include alkylene glycol (meth)acrylic acid diesters, polyoxyalkylene glycol (meth)acrylic acid diesters, polyhydric alcohol (meth)acrylic acid diesters, ethylene oxide or propylene oxide adducts ( meth)acrylic acid diesters, epoxy (meth)acrylates, urethane (meth)acrylates, polyester (meth)acrylates, and the like.
Among them, esters of polyhydric alcohol and (meth)acrylic acid are preferred. For example, pentaerythritol tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, PO-modified trimethylolpropane tri(meth)acrylate, EO Modified phosphoric acid tri(meth)acrylate, trimethylolethane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate ) acrylate, dipentaerythritol hexa(meth)acrylate, pentaerythritol hexa(meth)acrylate, 1,2,3-chlorohexanetetramethacrylate, polyurethane polyacrylate, polyester polyacrylate, and caprolactone-modified tris(acryloxyethyl) isocyanate nurate and the like.
The (meth)acrylate is a generic term including acrylate and methacrylate.

The content of the fluorine-containing resin in the antifouling layer is not particularly limited, but at least one of insect stain removability, scratch resistance, and insect stain removal after the scratch test is superior, so that the total mass of the antifouling layer is On the other hand, 1 to 100% by mass is preferable, and 5% by mass or more and less than 95% by mass is more preferable.

The antifouling layer may contain materials other than the fluorine-containing resin described above.
For example, the antifouling layer may contain inorganic particles.
Examples of inorganic particles include metal particles and metal oxide particles, and metal oxide particles are preferred from the viewpoint of transparency and scratch resistance. Materials constituting the metal oxide particles include, for example, silica (silicon oxide), titanium oxide, and zirconium oxide, with silica being preferred.
Although the average particle size of the inorganic particles is not particularly limited, it is preferably 5 nm or more and less than 500 μm, more preferably 10 nm or more and 300 μm, from the viewpoint of transparency.

The content of the inorganic particles in the antifouling layer is not particularly limited, but at least one of insect stain removability, scratch resistance, and insect stain removal after the scratch test is superior, so that the total mass of the antifouling layer is 1% by mass or more and less than 50% by mass, and more preferably 10% by mass or more and less than 40% by mass.

In addition to the inorganic particles described above, other materials include, for example, surface modifiers, UV inhibitors, and deterioration inhibitors.

The surface modifier is used for the purpose of improving the leveling property during application of the antifouling layer-forming composition described below, and for the purpose of enhancing the slip resistance of the antifouling layer to improve scratch resistance.
Examples of surface modifiers include various additives that modify surface physical properties and are commercially available under the names of surface conditioners, leveling agents, smoothness imparting agents, antifouling agents, and the like. Among them, fluorine-based surface modifiers and silicone-based surface modifiers are preferred.
Specific examples include perfluoroalkyl group-containing compounds such as perfluoroalkyl group-containing carboxylic acids or salts thereof, perfluoroalkyl group-containing sulfonic acids or salts thereof, perfluoroalkyl group-containing phosphoric acids or phosphoric acid esters thereof, A perfluoroalkenyl group-containing compound in which the perfluoroalkyl group is replaced with a perfluoroalkenyl group, a perfluoroether group-containing compound in which the above perfluoroalkyl group is replaced with a perfluoroether group, a fluorine-containing group/lipophilic group-containing oligomer, Oligomer containing fluorine group/hydrophilic group, oligomer containing fluorine group/hydrophilic group/lipophilic group, oligomer containing fluorine group/hydrophilic group/lipophilic group/carboxyl group, fluorine group/UV reactive group containing oligomer Examples include oligomers, silicone-based polymers and oligomers having silicone chains and polyalkylene oxide chains, and silicone-based polymers and oligomers having silicone chains and polyester chains.
Specific products include perfluorobutanesulfonate (product name “Megafac F-114”, manufactured by DIC Corporation), perfluoroalkyl group-containing carboxylate (product name “Megafac F-410”, DIC Co., Ltd.), perfluoroalkyl group/phosphoric acid group-containing phosphate ester (product name “Megafac F-510”, DIC Corporation), modified perfluoropolyether (product name “OPTOOL DAC-HP”) , manufactured by Daikin Industries, Ltd., product names "KY-108", "KY-164", "X-71-195", "KY-1900", manufactured by Shin-Etsu Chemical Co., Ltd.), fluorine-containing group, parent Oily group-containing oligomers (product names “Megaface F-281”, “Megaface F-253”, “Megaface F-251” manufactured by DIC Corporation), fluorine-containing group/hydrophilic group-containing oligomers (product names "Megafac F-430", "Megafac F-551", "Megafac F-552", manufactured by DIC Corporation), fluorine-containing group-hydrophilic group-lipophilic group-containing oligomer (product name "Megafac F-477", manufactured by DIC Corporation), fluorine-containing group-hydrophilic group-lipophilic group-carboxyl group-containing oligomer (product name "Megafac F-570" manufactured by DIC Corporation), fluorine-containing group- UV-reactive group-containing oligomers ((product names “Megafac RS-56”, “Megafac RS-90”, “Megafac RS-75”, manufactured by DIC Corporation), (product name “KY-1203”, manufactured by Shin-Etsu Chemical Co., Ltd.).
The content of the surface modifier in the composition for forming an antifouling layer, which will be described later, is not particularly limited. 0.05 to 10% by mass is preferred, and 0.1 to 10% by mass is more preferred.

The first embodiment of the sensor cover of the present invention may have layers other than the substrate and antifouling layer described above.
For example, an adhesion layer may be provided between the substrate and the antifouling layer to improve adhesion between the two.

The manufacturing method of the first embodiment of the sensor cover of the present invention is not particularly limited, and known methods can be used. Among them, a method of applying a composition for forming an antifouling layer containing a fluorine-containing monomer onto a substrate and subjecting the obtained coating film to a curing treatment is preferable.
The above method will be described in detail below.

The antifouling layer-forming composition contains a fluorine-containing monomer. The fluorine-containing monomer is as described above.
The antifouling layer-forming composition may contain materials other than the fluorine-containing monomer. Other materials include, for example, the polyfunctional monomers described above.
The contents of the fluorine-containing monomer and the polyfunctional monomer in the antifouling layer-forming composition are not particularly limited, and may be appropriately adjusted so that the content of the fluorine-containing resin in the antifouling layer is within the preferred range. is preferred.

The antifouling layer-forming composition may contain a polymerization initiator.
Polymerization initiators include known polymerization initiators, including photopolymerization initiators and thermal polymerization initiators, with photopolymerization initiators being preferred.
Photopolymerization initiators include acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones, azo compounds, peroxides, 2,3-dialkyldione compounds, disulfide compounds, fluoroamine compounds, aromatic sulfoniums, lophine dimers, onium salts, borate salts, active esters, active halogens, inorganic complexes, and coumarins.
The content of the polymerization initiator in the antifouling layer-forming composition is not particularly limited, but is preferably 0.1% by mass or more and less than 15% by mass with respect to the total mass of the monomers in the antifouling layer-forming composition. 1 mass % or more and less than 10 mass % is more preferable.

The antifouling layer-forming composition may contain a solvent. The type of solvent is not particularly limited, and includes water and organic solvents.
Examples of organic solvents include ketone-based solvents, alcohol-based solvents, ester-based solvents, and fluorine-based solvents.
Although the content of the solvent in the antifouling layer-forming composition is not particularly limited, it is preferably 10% by mass or more and less than 95% by mass based on the total mass of the antifouling layer-forming composition from the viewpoint of coating properties. % by mass or more and less than 80% by mass is more preferable.

The coating method is not particularly limited, and examples thereof include spin coating, spray coating, brush coating, roller coating, bar coating, and dip coating.
In addition, if necessary, after applying the antifouling layer-forming composition, a treatment for drying the coating film applied on the base material may be performed. The solvent can be removed from the coating film by performing a drying treatment.

The procedure of curing treatment applied to the coating film is not particularly limited, and includes photocuring treatment and heat curing treatment. Among them, light irradiation treatment is preferable, and ultraviolet irradiation treatment is more preferable.
A light source such as an ultraviolet lamp is used for ultraviolet irradiation.
Although the irradiation amount of light (eg, ultraviolet rays) is not particularly limited, it is generally preferably 100 to 800 mJ/cm ² .
The atmosphere for the light irradiation is not particularly limited, and the light irradiation may be carried out in the air, or the light irradiation may be carried out in an inert atmosphere.

<<Second Embodiment>>
A second embodiment of the sensor cover of the present invention is a sensor cover having a base material and an antifouling layer, wherein the contact angle to water on the surface of the antifouling layer opposite to the base material side is 70°. and a contact angle to methylene iodide of 40° or more, and a depth of 50 nm and a depth of 100 nm along the thickness direction from the surface of the antifouling layer opposite to the substrate side. 150 nm depth position, 200 nm depth position, and 250 nm depth position, the contact angle to water at each position is 70° or more, and the contact angle to methylene iodide is 40° or more. and the antifouling layer has a thickness of 500 nm to 20 μm.

The base material of the second embodiment of the sensor cover of the present invention is the same as the base material in the above-described first embodiment, so the description is omitted.

In the second embodiment of the sensor cover of the present invention, the surface of the antifouling layer opposite to the substrate has a contact angle to water of 70° or more and a contact angle to methylene iodide of 40° or more. is.
The contact angle with water is preferably 80° or more, more preferably 85° or more, in that at least one of insect stain removability, scratch resistance, and insect stain removal after a scratch test is superior. The upper limit of the contact angle with water is not particularly limited, and is often 150° or less, more often 120° or less.
As a method for measuring the contact angle with water on the surface of the antifouling layer opposite to the substrate side, first, a contact angle meter (“CA-X” type contact angle meter, manufactured by Kyowa Interface Science Co., Ltd.) , in a dry state (20 ° C./65% RH), using pure water as a liquid, a droplet with a diameter of 1.0 mm is made at the tip of the needle, and this is brought into contact with the surface of the antifouling layer to form the antifouling layer Make a droplet on top. Next, an angle formed by a tangent line to the surface of the antifouling layer and the surface of the antifouling layer at the point where the antifouling layer and the liquid contact is defined as a contact angle, which is the angle on the side containing the liquid, and is measured.

Further, the contact angle with respect to methylene iodide is preferably 55° or more from the viewpoint that at least one of insect stain removability, scratch resistance, and insect stain removal after a scratch test is superior. The upper limit of the contact angle to methylene iodide is not particularly limited, and is often 140° or less, more often 100° or less.
As a method for measuring the contact angle to methylene iodide on the surface of the antifouling layer opposite to the substrate side, there is a method using methylene iodide instead of water in the above-described method for measuring the contact angle to water. mentioned.

In the second embodiment of the sensor cover of the present invention, from the surface of the antifouling layer on the side opposite to the substrate side, along the thickness direction, the depth position of 50 nm, the depth position of 100 nm, and the depth position of 150 nm , 200 nm depth, and 250 nm depth, the contact angle to water is 70° or more, and the contact angle to methylene iodide is 40° or more. More specifically, from the surface 14S of the antifouling layer on the side opposite to the substrate side, along the thickness direction (toward the substrate side), the depth position of 50 nm is defined as the depth position D1, and the depth position is 100 nm. A depth position of 150 nm is defined as a depth position D2, a depth position of 150 nm is defined as a depth position D3, a depth position of 200 nm is defined as a depth position D4, and a depth position of 250 nm is defined as a depth position D5. In fact, the contact angle to water at each depth position is 70° or more, and the contact angle to methylene iodide is 40° or more.
At any of the above positions (depth position D1, depth position D2, depth position D3, depth position D4, depth position D5), the water contact angle , 80° or more is preferable, and 82° or more is more preferable, because at least one of the removal of insect stains after the abrasion test is more excellent. The upper limit of the contact angle with water is not particularly limited, and is often 150° or less, more often 120° or less.
Further, at any of the above positions (depth position D1, depth position D2, depth position D3, depth position D4, depth position D5), the contact angle to the methylene iodide was An angle of 55° or more is preferable in that at least one of abrasion resistance and removal of insect stains after the abrasion test is superior. The upper limit of the contact angle to methylene iodide is not particularly limited, and is often 140° or less, more often 100° or less.

As a method for measuring the contact angle with water at each of the above positions (depth position D1, depth position D2, depth position D3, depth position D4, depth position D5), first, from the surface of the antifouling layer to a predetermined A method of measuring the contact angle of water on the surface of the antifouling layer on the side opposite to the base material side with respect to the exposed surface when the etching process is performed to the depth position and the predetermined depth position is reached. Measure the contact angle with water in the same manner as
In addition, an etching process implements an Ar etching process.
As a method for measuring the contact angle of methylene iodide at each of the above positions (depth position D1, depth position D2, depth position D3, depth position D4, depth position D5), instead of water in the method described above, A method using methylene iodide is mentioned.

In the second embodiment of the sensor cover of the present invention, the thickness of the antifouling layer is 500 nm to 20 μm, preferably 4 μm or more and less than 18 μm, and more preferably 8 μm or more and less than 16 μm, in terms of the balance between scratch resistance and curl suppression. more preferred.
The thickness of the antifouling layer is obtained by measuring the thickness of the entire sensor cover at 20 arbitrary positions with a contact-type film thickness meter (manufactured by Mitutoyo), and subtracting the thickness of the base material from the average value. Ask for it. As the contact terminal, a cylindrical terminal having a bottom surface with a diameter of 0.5 cm is used. The measurement pressure is 0.1N.
In addition, the thickness of a base material is the thickness calculated by the method mentioned above.

The materials contained in the antifouling layer and the manufacturing method of the antifouling layer of the second embodiment of the sensor cover of the present invention are the same as the materials contained in the antifouling layer and the manufacturing method of the antifouling layer of the first embodiment described above. Therefore, the description is omitted.

The sensor cover of the present invention (first and second embodiments described above) can be suitably used as a cover for protecting a light-emitting element such as a laser and a camera.
The sensor cover of the present invention may have a three-dimensional shape.
When the sensor cover has a three-dimensional shape, the manufacturing method of the sensor cover includes a method of manufacturing a flat sensor cover and then molding it so as to have a three-dimensional shape, and a method of forming an antifouling layer on a base material having a three-dimensional shape. There is a method of pasting. Alternatively, the antifouling layer may be formed by applying the antifouling layer-forming composition onto a substrate having a three-dimensional shape by spray coating or dip coating.
Preferably, the sensor includes a light emitting element and a light receiving element.
The type of light-emitting element included in the sensor is not particularly limited, and an optimum light-emitting element is selected according to the intended use. Examples of light-emitting devices include semiconductor light-emitting devices such as laser diodes and light-emitting diodes.
The light-receiving element is configured to output a light-receiving signal corresponding to the amount of incident light. Examples of light-receiving elements include photodiodes, phototransistors, and photoresistors.
The sensor may also include other components (eg, a processor), if desired.

A sensor including the sensor cover of the present invention can be used in a variety of applications. For example, there is LiDAR using infrared rays. More specifically, for example, a sensor including the sensor cover of the present invention is mounted on a vehicle as a moving body, irradiates a laser beam in front of the moving body by two-dimensional scanning, and emits laser light from the moving body to the front of the moving body. can measure the distance to an object in The sensor cover of the present invention is preferably used for sensors containing lasers with emission wavelengths of 800 to 2000 nm, and more preferably for sensors containing lasers with emission wavelengths of 905 nm or 1550 nm.
In addition, the sensor to which the sensor cover of the present invention is applied is not limited to a vehicle sensor. can also be used for

The features of the present invention will be described more specifically below with reference to examples and comparative examples. The materials, amounts used, proportions, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the gist of the present invention. Therefore, the scope of the present invention should not be construed as being restricted by the specific examples shown below.

<Example 1>
The following compound M-1 (the numerical value in the structural formula represents the content of fluorine atoms in the compound.) 94 parts by mass, and the initiator (Irgacure (registered trademark) 127 (manufactured by BASF Corporation)) 6 mass and the resulting mixture was mixed with methyl ethyl ketone to prepare composition 1 for forming an antifouling layer.
The content of methyl ethyl ketone in the composition for forming an antifouling layer was 95% by mass with respect to the total mass of the composition for forming an antifouling layer.

A composition 1 for forming an antifouling layer was applied onto a polycarbonate film (Technolloy C000 (registered trademark), film thickness 125 μm, manufactured by Sumitomo Chemical Co., Ltd.) as a transparent substrate using a wire bar. The resulting coating film on the transparent substrate was dried at 100°C. Thereafter, while purging with nitrogen to create an atmosphere with an oxygen concentration of 1.0% by volume or less, an air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) of 160 W/cm was used with an illuminance of 400 mW/cm ² and an irradiation amount. The coating film was cured by irradiating ultraviolet rays of 500 mJ/cm ² to form an antifouling layer having a thickness of 10 μm, and a sensor cover 1 was obtained.

<Examples 2 to 14, Comparative Examples 1 to 4>
As shown in Table 1, which will be described later, the type and amount of the fluorine-containing monomer used were changed, other materials were used, and the thickness of the formed antifouling layer was adjusted. According to the same procedure, sensor covers 2 to 14 and sensor covers C1 to C4 were obtained.
The content of methyl ethyl ketone in the antifouling layer-forming composition prepared in each of Examples and Comparative Examples was 95% by mass with respect to the total mass of the antifouling layer-forming composition.

The compounds listed in Table 1 are as follows.
Compound M-4 (hereinafter, see the structural formula. The numerical value in the structural formula represents the content of fluorine atoms in the compound.)

Compound M-9 (see the structural formula below. The numerical value in the structural formula represents the content of fluorine atoms in the compound.)

Compound M-12 (see the structural formula below. The numerical value in the structural formula represents the content of fluorine atoms in the compound.)

Compound M-16 (see the structural formula below. The numerical value in the structural formula represents the content of fluorine atoms in the compound.)

Megafac RS-90: Megafac RS-90 (manufactured by DIC Corporation)
DPHA: KAYARAD DPHA (mixture of dipentaerythritol hexaacrylate/dipentaerythritol pentaacrylate) (manufactured by Nippon Kayaku Co., Ltd.)
PET-30: KAYARAD PET-30 (mixture of pentaerythritol triacrylate/pentaerythritol tetraacrylate) (manufactured by Nippon Kayaku Co., Ltd.)
Particles: Organosilica sol (registered trademark) MEK-AC-2140Z (manufactured by Nissan Chemical Industries, Ltd.)

In Table 1, the "number of polymerizable groups" column represents the number of polymerizable groups in the fluorine-containing monomer.
The "fluorine content" column represents the content (% by mass) of fluorine atoms in the fluorine-containing monomer.
The "Thickness (μm)" column represents the thickness (μm) of the antifouling layer. A method for measuring the thickness of the antifouling layer will be described in detail later.

<Measurement>
(Ratio of fluorine atoms on the surface of the antifouling layer opposite to the substrate side)
The ratio of fluorine atoms on the surface opposite to the transparent substrate side of the antifouling layer of the sensor cover obtained in each example and comparative example was confirmed by analysis by X-ray photoelectron spectroscopy. Specific analysis conditions are as follows. The results are collectively shown in Table 2, which will be described later.
The ratio of fluorine atoms is the ratio (atomic %) to the total amount of fluorine atoms, carbon atoms, oxygen atoms and nitrogen atoms on the surface of the antifouling layer opposite to the transparent substrate.
X-ray source: monochromatic Al-α
Measurement area: F1s, C1s, O1s, N1s
Take-off angle: 45°

(Ratio of fluorine atoms inside the antifouling layer)
Predetermined depth positions from the surface opposite to the transparent substrate side of the antifouling layer of the sensor cover obtained in each example and comparative example (depths from the surface of 50 nm, 100 nm, 150 nm, 200 nm, and 250 nm each position), and when it reaches a predetermined depth position, at that position (ratio of fluorine atoms on the surface opposite to the base material side of the antifouling layer). Analysis by X-ray photoelectron spectroscopy was performed under the conditions of , and the ratio of fluorine atoms was calculated. In addition, the etching process implemented Ar etching process. The results are collectively shown in Table 2, which will be described later.

(Contact angle on the surface opposite to the substrate side of the antifouling layer)
As a method for measuring the contact angle with water on the surface of the antifouling layer of the sensor cover obtained in each example and comparative example opposite to the transparent substrate side, first, a contact angle meter ("CA-X "type contact angle meter, manufactured by Kyowa Interface Science Co., Ltd.), in a dry state (20 ° C. / 65% RH), using pure water as a liquid, make a droplet with a diameter of 1.0 mm on the tip of the needle, This was brought into contact with the surface of the antifouling layer to form droplets on the antifouling layer. Next, the contact angle was defined as the angle formed by the tangent to the liquid surface and the surface of the antifouling layer at the point where the antifouling layer and the liquid were in contact, and the angle on the side containing the liquid was taken as the contact angle.
The contact angle to methylene iodide on the surface of the antifouling layer of the sensor cover opposite to the transparent base material side was measured in the same manner except that methylene iodide was used instead of water. The results are collectively shown in Table 3, which will be described later.

(Contact angle inside antifouling layer)
Predetermined depth positions from the surface opposite to the transparent substrate side of the antifouling layer of the sensor cover obtained in each example and comparative example (depths from the surface of 50 nm, 100 nm, 150 nm, 200 nm, and 250 nm ), and when reaching a predetermined depth position, the same conditions as described above (contact angle on the surface of the antifouling layer on the side opposite to the base material side) at that position The contact angle to water and the contact angle to methylene iodide were measured. In addition, the etching process implemented Ar etching process. The results are collectively shown in Table 3, which will be described later.

(Thickness of antifouling layer)
The thickness of the antifouling layer of the sensor cover obtained in each example and comparative example was measured by measuring the thickness of the entire sensor cover at 20 arbitrary positions with a contact-type film thickness meter (manufactured by Mitutoyo). It was obtained by subtracting the thickness of the transparent substrate from the averaged value. As the contact terminal, a cylindrical terminal having a bottom surface with a diameter of 0.5 cm is used. The measurement pressure is 0.1N.
The thickness (average thickness) of the transparent base material was obtained by measuring the thickness of the transparent base material at 20 arbitrary positions with a contact-type film thickness meter (manufactured by Mitutoyo) and averaging the results.

<Evaluation>
(Scratch resistance evaluation)
Using HEIDON-18S, a rubbing test was performed on the surface of the antifouling layer of the sensor cover obtained in each of the examples and comparative examples on the side opposite to the transparent substrate side. More specifically, a rubbing material was wrapped around the rubbing tip (1 cm×1 cm) of the tester that was in contact with the antifouling layer, and the band was fixed, and a rubbing test was performed under the conditions described later.
Evaluation environmental conditions: 25°C, 60% RH
Rubbing material: Steel wool (Nippon Steel Wool Co., Ltd., Gelade No. 0000)
Travel distance (one way): 10 cm,
Scraping speed: 100 mm/sec,
Load: 250 g/cm ² ,
Tip contact area: 1 cm x 1 cm,
Number of times of rubbing: 20000 reciprocations.
After rubbing, apply oil-based black ink to the back surface of the sensor cover (the surface opposite to the antifouling layer side of the transparent base material), and visually observe with reflected light, and check the following for scratches on the rubbed part of the antifouling layer. was evaluated according to the criteria of
A: No flaws are visible even when viewed very carefully.
B: Slightly weak scratches can be seen when viewed very carefully, but are acceptable for practical use.
C: Weak scratches are visible.

(Evaluation of insect stain removability)
After the cricket placed on the antifouling layer of the sensor cover obtained in each example and comparative example was completely crushed by applying a load, the transparent base material with the antifouling layer whose surface was contaminated was dried at 80°C for 30 minutes. let me Next, using an air spray gun (W-101-101G, manufactured by Anest Iwata Co., Ltd.), water is sprayed for 10 minutes at a condition of 95 mL / min, dried, and then the antifouling layer is visually observed. Observations were made and the degree of staining was evaluated according to the following criteria. The results are collectively shown in Table 4, which will be described later. The distance between the air spray gun and the transparent substrate with antifouling layer was 10 cm. The results are collectively shown in the "Before abrasion test" column of the "Insect stain removal" column in Table 4, which will be described later.
A: No dirt can be seen even when viewed very carefully.
B: Stain is slightly visible when viewed very carefully, but acceptable for practical use.
C: Dirt is visible.

(Evaluation of insect stain removability after scratch test)
The above-described (insect stain removability evaluation) was performed on the antifouling layer surface of the sensor cover obtained by performing the above-described (scratch resistance evaluation). The results are collectively shown in the "After Scratch Test" column of the "Insect Stain Removability" column in Table 4, which will be described later.

(Curl evaluation)
The sensor cover obtained in each example and comparative example was cut into a square with a side of 10 cm, and the obtained sample was placed on a horizontal surface with the antifouling layer side up and stored in an environment of 23 ° C. and 50% RH for 48 hours. did. After that, the height from the horizontal plane of the four warped ends of the obtained sample was measured, and the average value was taken as the curl height, and evaluated according to the following criteria. A value of B or higher is regarded as a practically acceptable range. The results are collectively shown in Table 4, which will be described later.
A: Curl height of less than 5 mm B: Curl height of 5 mm or more and less than 15 mm C: Curl height of 15 mm or more

As shown in Table 4, it was confirmed that the sensor cover of the present invention exhibited the desired effect.
Further, from a comparison between Example 5 and other examples, it was confirmed that when the number of polymerizable groups (polymerizable unsaturated groups) in the fluorine-containing monomer is 5 or more, the scratch resistance is more excellent.
Further, from the comparison of Examples 12 to 14, it was confirmed that when the content of the inorganic particles was 10% by mass or more, the scratch resistance was more excellent.
Further, from comparison with Examples 8 to 10, it was confirmed that when the content of the polyfunctional monomer was 30% by mass or less, the curl was more excellent.
From the results of the above Examples, it was confirmed that when the ratio of fluorine atoms on the surface of the antifouling layer opposite to the substrate side is 36 atomic % or more, the insect stain removability before the scratch test is more excellent.
From the results of the above Examples, it was confirmed that when the ratio of fluorine atoms at each depth position of the antifouling layer was 32 atomic % or more, the insect stain removability after the abrasion test was more excellent.
From the results of the above Examples, it was confirmed that when the contact angle to water on the surface of the antifouling layer opposite to the substrate side is 85° or more, the insect stain removability before the scratch test is more excellent.
From the results of the above Examples, it was confirmed that when the contact angle with respect to water at each depth position of the antifouling layer was 82° or more, the insect stain removability after the scratch test was more excellent.

The sensor cover obtained in each example was placed in front of an optical system sensor such as a commercially available camera or LiDAR with the antifouling layer facing outward to fabricate the sensor. The resulting sensor was confirmed to be functional.

10 sensor cover 12 base material 14 antifouling layer

Claims (10)

1. A sensor cover having a base material and an antifouling layer,
   The ratio of fluorine atoms on the surface of the antifouling layer opposite to the base material is 20 atomic% or more,
   From the surface of the antifouling layer opposite to the substrate, along the thickness direction, a depth position of 50 nm, a depth position of 100 nm, a depth position of 150 nm, a depth position of 200 nm, and a depth position of 250 nm. The ratio of fluorine atoms at each position of the depth position is 20 atomic% or more,
   The sensor cover, wherein the antifouling layer has a thickness of 500 nm to 20 μm.
2. A sensor cover having a base material and an antifouling layer,
   The surface of the antifouling layer opposite to the substrate has a contact angle of 70° or more with respect to water and a contact angle of 40° or more with respect to methylene iodide,
   From the surface of the antifouling layer opposite to the substrate, along the thickness direction, a depth position of 50 nm, a depth position of 100 nm, a depth position of 150 nm, a depth position of 200 nm, and a depth position of 250 nm. The contact angle to water at each position of the depth position is 70 ° or more, and the contact angle to methylene iodide is 40 ° or more,
   The sensor cover, wherein the antifouling layer has a thickness of 500 nm to 20 μm.
3. The sensor cover according to claim 1 or 2, wherein the antifouling layer contains a fluorine-containing resin having a repeating unit derived from a fluorine-containing monomer.
4. The sensor cover according to claim 3, wherein the fluorine-containing monomer has a polymerizable unsaturated group.
5. The sensor cover according to claim 3 or 4, wherein the fluorine-containing monomer has 3 to 6 polymerizable unsaturated groups.
6. The sensor cover according to any one of claims 3 to 5, wherein the fluorine atom content in the fluorine-containing monomer is 38.0 to 50.0% by mass.
7. The sensor cover according to any one of claims 3 to 6, wherein the fluorine-containing resin has repeating units derived from a polyfunctional monomer having no fluorine atoms and having three or more polymerizable unsaturated groups.
8. The sensor cover according to any one of claims 1 to 7, wherein the antifouling layer contains inorganic particles.
9. The sensor cover according to claim 8, wherein the inorganic particles are silica particles.
10. A sensor comprising the sensor cover according to any one of claims 1 to 9.

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