JP2017001303A - Translucent member with hydrophilic film, manufacturing method of translucent member with hydrophilic film, and in-vehicle camera equipped with translucent member with hydrophilic film - Google Patents

Abstract

A light-transmitting member with a hydrophilic film having a higher hydrophilic property than before, a method for manufacturing the light-transmitting member with a hydrophilic film, An in-vehicle camera provided with the light-transmitting member with a hydrophilic film is provided. A translucent member with a hydrophilic film according to the present invention is a translucent member with a hydrophilic film in which a hydrophilic film is formed on a surface of a translucent substrate, and the hydrophilic film is made of amorphous silica as a base material. A hydroxyalkyleneamino group is bonded to the surface region of the matrix through an organic chain X, and the organic chain X is an alkylene chain or an alkyleneoxyalkylene chain. [Selection] Figure 1

Description

  The present invention relates to a technique for suppressing image disturbance due to water droplet adhesion, and in particular, a translucent member (for example, a lens or a lens cover) having a hydrophilic film formed on the surface, a method for producing the translucent member with the hydrophilic film, and the hydrophilic The present invention relates to an in-vehicle camera including a translucent member with a film.

  In recent years, in-vehicle cameras for observing the situation outside the vehicle are rapidly spreading for the purpose of improving safety when driving a car. Such an in-vehicle camera may be installed inside the vehicle, but is preferably outside the vehicle when observing a wider range.

  However, when the in-vehicle camera is installed outside the vehicle, if a water droplet adheres to the lens of the in-vehicle camera due to weather conditions or the like, there is a weakness that it becomes difficult to observe the out-of-vehicle condition because light incident on the camera is scattered. Various techniques for overcoming such weak points have been studied.

  For example, in Patent Document 1 (Japanese Patent Laid-Open No. 2011-240910), a cleaning liquid supplied from a cleaning liquid tank capable of storing a cleaning liquid is sprayed onto a camera cover to which a camera can be attached and detached toward a lens surface of a camera lens. An in-vehicle optical sensor cover provided with a cleaning nozzle for cleaning a lens surface is disclosed. According to Patent Document 1, a compressed air generating unit for injecting compressed air is unnecessary, and while reducing costs and downsizing, it is possible to appropriately remove deposits adhering to the lens surface, and to properly It can be operated.

  Patent Document 2 (Japanese Translation of PCT International Publication No. 2005-523981) discloses an aqueous coating composition for providing a durable hydrophilic coating on the surface of an object, which is a) dispersed or emulsified in water and a polymer. A polyfunctional polymeric carrier capable of forming a matrix; b) a hydrophilic water-soluble organic monomer, oligomer, prepolymer, polymer or copolymer; c) a polyfunctional aqueous colloidal metal oxide; d) a polyfunctional crosslink. And a coating composition comprising: an agent; According to Patent Document 2, coating with the coating composition improves water sheeting and prevents water condensation, so that it can impart antifogging properties to the coated substrate.

  Patent Document 3 (Japanese Patent Application Laid-Open No. 2004-123996) discloses a hydrophilic film formed on a resin, the hydrophilic film being formed of an inorganic oxide, and having a size of 20 to 200 nm in the hydrophilic film. There is disclosed a hydrophilic film having voids, wherein the inorganic oxide is formed of an alkoxysilane compound polymer having silicon oxide and amino groups. According to Patent Document 3, it is said that a high-hardness hydrophilic film can be formed on the surface of a resin base material having a low heat-resistant temperature.

JP2011-240910A JP 2005-523981 A JP 2004-123996 A

  However, the technique described in Patent Document 1 has a demerit that a mechanism for ejecting the cleaning liquid and a space for housing the mechanism are required. In particular, in an in-vehicle device of an automobile, weight reduction and space saving of the device are one of the most important issues, and if possible, it is desirable not to require such a mechanism.

  On the other hand, in the techniques described in Patent Documents 2 and 3, by forming a hydrophilic coating (hydrophilic film) on a substrate such as a lens, water droplets can be formed without any special drive mechanism when water adheres to the substrate. It is expected that formation is suppressed (a water film is formed). However, when the present inventors investigated in detail the state of water droplet formation suppression (state of water film formation) in the techniques of Patent Documents 2 and 3, the initial stage of water adhesion (stage where the amount of water attached is relatively small). ), The formation of a water film was insufficient, and it was found that a certain amount of adhering water was required to form a uniform water film.

  This is because the degree of hydrophilicity in the conventional hydrophilic coating is not sufficiently high (for example, the contact angle with water is not sufficiently small), and the water film formation with a certain amount of adhering moisture is uniform. It was thought that it was necessary. In other words, in order to achieve uniform water film formation with a smaller amount of attached water, it was considered that a coating having higher hydrophilicity was necessary.

  Therefore, an object of the present invention is to enable a rapid water film formation even at the initial stage of moisture adhesion, and therefore, a light-transmitting member with a hydrophilic film having higher hydrophilicity than the conventional one, and the light-transmitting member with a hydrophilic film And a vehicle-mounted camera provided with the light-transmitting member with the hydrophilic film.

(I) One aspect of the present invention is a translucent member with a hydrophilic film in which a hydrophilic film is formed on the surface of the translucent substrate,
The hydrophilic film has amorphous silica as a parent phase, and a hydroxyalkyleneamino group is bonded to a surface region of the parent phase via an organic chain X,
The organic chain X is an alkylene chain or an alkyleneoxyalkylene chain, and provides a transparent member with a hydrophilic film.

(II) Another embodiment of the present invention is a method for producing a light-transmitting member with a hydrophilic film in which a hydrophilic film is formed on the surface of the light-transmitting substrate,
The hydrophilic film has amorphous silica as a parent phase, and a hydroxyalkyleneamino group is bonded to a surface region of the parent phase via an organic chain X,
The organic chain X is an alkylene chain or an alkyleneoxyalkylene chain,
The manufacturing method comprises preparing a hydrophilic film paint comprising an alkoxysilane having a silica structure, an alkoxysilane having a glycidyl group and the organic chain X, an amine having a hydroxy group, and a lower alcohol. Process,
A hydrophilic film forming step of forming the hydrophilic film using the hydrophilic film paint,
The hydrophilic film forming step includes a paint application step of applying the hydrophilic film paint to the surface of the light-transmitting substrate, and a film curing reaction step of heating the applied coating film to advance the curing reaction of the hydrophilic film. The manufacturing method of the translucent member with a hydrophilic film characterized by including this is provided.

(III) Still another aspect of the present invention is an in-vehicle camera disposed on the outer periphery of the vehicle,
A translucent member included in the in-vehicle camera is the above-described translucent member with a hydrophilic film according to the present invention.

  According to the present invention, in order to enable rapid water film formation even at the initial stage of water adhesion, a hydrophilic film-containing translucent member having higher hydrophilicity than the prior art, and production of the hydrophilic film-coated translucent member A method and a vehicle-mounted camera using the light-transmitting member with a hydrophilic film can be provided.

It is the chemical structure schematic diagram which showed the chemical structure example of the hydrophilic film in the translucent member with a hydrophilic film which concerns on this invention. It is the chemical structure schematic diagram which showed the other chemical structure example of the hydrophilic film in the translucent member with a hydrophilic film which concerns on this invention. It is a chemical structure schematic diagram which shows an example of the first stage of the film hardening reaction in a film hardening reaction process. It is a chemical structure schematic diagram which shows an example of the latter stage of the film hardening reaction in a film hardening reaction element process. It is a chemical structure schematic diagram which shows another example of the latter stage of the film hardening reaction in a film hardening reaction element process. It is a cross-sectional schematic diagram which shows an example of the vehicle-mounted camera which comprises the translucent member with a hydrophilic film which concerns on this invention. It is a cross-sectional SEM observation image which shows the transparent member with a hydrophilic film produced using the coating material D for hydrophilic films. It is a cross-sectional SEM observation image which shows the transparent member with a hydrophilic film produced using the coating material J for hydrophilic films.

The present invention can add the following improvements and changes to the above-described light-transmitting member with a hydrophilic film (I) according to the present invention.
(I) The hydroxyalkyleneamino group is a secondary or tertiary amino group.
(Ii) The hydroxyalkyleneamino group has an aromatic ring, and the amino group is directly bonded to the aromatic ring.
(Iii) The surface arithmetic average roughness of the hydrophilic film is 10 nm or less.
(Iv) The hydrophilic film further contains silica particles having an average particle diameter of 5 nm to 15 nm.
(V) A film made of silica (silicon oxide) or alumina (aluminum oxide) is further formed between the hydrophilic film and the translucent substrate.
(Vi) The contact angle between the hydrophilic film and water is less than 10 °.
(Vii) The hydrophilic film has a pencil hardness of 5H or more.

In addition, the present invention can be modified or changed as described below in the method (II) for producing a light-transmitting member with a hydrophilic film according to the present invention described above.
(Viii) In the film curing reaction step, the alkoxysilane having the silica structure and the alkoxysilane having the glycidyl group and the organic chain X are polymerized to form an amorphous silica film on the translucent substrate. An alkoxylane polymer process,
A glycidyl group-amino group compound process in which the glycidyl group and the amino group of the amine are combined.
(Ix) The coating for a hydrophilic film has the silica structure when the mixing ratio of the alkoxysilane having the silica structure and the alkoxysilane having the glycidyl group and the organic chain X is 100 parts by mass. Is contained in an amount of 10 to 50 parts by mass.
(X) The hydrophilic film-coating material further contains silica particles having an average particle diameter of 5 nm or more and 15 nm or less.
(Xi) The manufacturing method further includes a translucent base material preparation step of forming a silica film or an alumina film on the surface of the translucent base material.

(Basic idea of the present invention)
As described above, it has been considered that there is room for improvement in the degree of hydrophilicity of the conventional hydrophilic film. In order to improve the hydrophilicity, it is considered that one of the points is how many hydrophilic groups (for example, hydroxy group: —OH group) are unevenly distributed on the surface of the hydrophilic film. Therefore, the present inventors diligently studied a film forming process in which as many hydroxy groups as possible are unevenly distributed on the film surface.

  Through this research, the present inventors have found that two types of alkoxysilanes (alkoxysilane having a silica structure, alkoxysilane having a glycidyl group and an organic chain X) for forming a matrix phase of the hydrophilic film, and a hydrophilic group in the film. Has developed a novel coating for hydrophilic films, which is a mixture of an amine having a hydroxy group for supplying water and a lower alcohol as a solvent. And it was discovered that the hydrophilic film obtained using the said coating material for hydrophilic films increases hydrophilicity conventionally (it can reduce a contact angle with water).

  The reason for this is that during the curing reaction of the film, an amorphous silica film based on alkoxysilane is formed, and the glycidyl group and the amino group combine to form a hydroxy group resulting from ring opening of the glycidyl group. It was considered that the hydroxyl group of the amine was unevenly distributed on the surface of the amorphous silica film. The present invention has been completed based on this finding.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments described here, and can be appropriately combined and improved without departing from the technical idea of the present invention.

[Translucent member with hydrophilic film]
FIG. 1 is a chemical structure schematic diagram showing an example of a chemical structure of a hydrophilic film in a light-transmitting member with a hydrophilic film according to the present invention. FIG. 2 is a chemical structure schematic diagram showing another example of the chemical structure of the hydrophilic film in the transparent member with a hydrophilic film according to the present invention. FIG. 1 shows the case where diethanolamine is used as the amine having a hydroxy group in the coating for a hydrophilic film, and FIG. 2 shows the case where 4-aminobenzyl alcohol is used as the amine having a hydroxy group.

  As shown in FIG. 1, the transparent member 100 with a hydrophilic film according to the present invention is such that a hydrophilic film 20 is formed on the surface of a transparent substrate 10, and the hydrophilic film 20 is an amorphous silica film. 21 is a parent phase, and a hydroxyalkyleneamino group 22 is bonded to the surface region of the parent phase via an organic chain X (an alkylene chain or an alkyleneoxyalkylene chain). Similarly, the hydrophilic film 20 ′ of the transparent member with a hydrophilic film 100 ′ shown in FIG. 2 has an amorphous silica film 21 as a parent phase, and a hydroxyalkyleneamino group 22 ′ is an organic chain in the surface region of the mother phase. It is connected through X.

  The hydroxy group of the hydroxyalkyleneamino group 22 in FIG. 1 includes a hydroxy group resulting from ring opening of a glycidyl group in addition to the hydroxy group of diethanolamine as a hydrophilic film coating component. Similarly, the hydroxy group of the hydroxyalkyleneamino group 22 ′ in FIG. 2 includes a hydroxy group resulting from ring opening of the glycidyl group in addition to the hydroxy group of 4-aminobenzyl alcohol of the hydrophilic film coating component. . Further, as the glycidyl group is opened, the hydroxyalkyleneamino group 22, 22 'becomes a secondary or tertiary amino group. By the above reaction, more hydroxy groups can be unevenly distributed in the surface region of the hydrophilic film 20, and the hydrophilicity of the hydrophilic film 20 can be enhanced.

[Method for producing translucent member with hydrophilic film]
The present invention will be described in more detail along with a method for producing a transparent member with a hydrophilic film.

(Translucent base material preparation process)
A translucent substrate is prepared. In the present invention, the translucent substrate 10 is not particularly limited, and conventional materials (for example, glass and resin) can be used. Further, if necessary, another functional light-transmitting film (for example, an antireflection film, a weather-resistant film, an acid-resistant film) may be formed on the surface of the light-transmitting substrate before forming the hydrophilic film.

  For example, when a material having a high ion binding property (for example, lanthanum-boron glass) is used as the light-transmitting substrate, when exposed to water in which atmospheric sulfur oxide or nitrogen oxide is dissolved, There is a possibility that a part of the water permeates the transparent substrate through the hydrophilic film. In order to prevent such erosion, it is preferable to form a silica film (silicon oxide film) or an alumina film (aluminum oxide film) on the surface of the translucent substrate.

(Paint preparation process for hydrophilic film)
A coating preparation process for a hydrophilic film for preparing a coating for forming the hydrophilic film is performed. The coating for a hydrophilic film used in the present invention comprises two types of alkoxysilanes (alkoxysilane having a silica structure, alkoxysilane having a glycidyl group and an organic chain X) for forming a matrix of the hydrophilic film, and a hydrophilic group in the film. Is a mixture of an amine having a hydroxy group for supplying a lower alcohol as a solvent.

  Each component of the coating for hydrophilic film will be specifically described.

(1) Alkoxysilane having a silica structure The alkoxysilane having a silica structure used in the present invention is a compound commonly referred to as silica sol, and forms the matrix (amorphous silica film 21) of the hydrophilic film of the present invention. . This compound is prepared, for example, by heating a compound having a tetraalkoxysilane structure (for example, tetramethylorthosilicate, tetraethylorthosilicate) in weak acidity for several tens of minutes, and polymerizing until the molecular weight reaches tens of thousands. be able to.

(2) Alkoxysilane having glycidyl group and organic chain X The alkoxysilane having glycidyl group and organic chain X used in the present invention is a compound in which the glycidyl group is bonded to alkoxysilane via organic chain X, The glycidyl group is combined with the alkoxysilane having the above silica structure while making the glycidyl group unevenly distributed in the surface region of the amorphous silica film 21, thereby forming a part of the parent phase of the hydrophilic film. The glycidyl group unevenly distributed in the surface region of the amorphous silica film 21 serves as a joint for coupling with an amine having a hydroxy group described later. Specifically, as an alkoxysilane having a glycidyl group and an organic chain X, it is preferable to use a compound having a general formula represented by the following compounds 1 to 4.

Here, R and R1 in the above compounds 1 to 4 are alkyl groups, and examples thereof include a methyl group (—CH ₃ ), an ethyl group (—C ₂ H ₅ ), and a propyl group (—C ₃ H ₇ ). It is done.

In addition, the organic chain X in the compounds 1 to 4 is an alkylene group or an alkyleneoxyalkylene group, and the number of carbon atoms in these groups is preferably 10 or less so as to be easily dissolved in a solvent. For example, a methylene group (—CH ₂ —), an ethylene group (—C ₂ H ₄ —), a propylene group (—C ₃ H ₆ —), a butylene group (—C ₄ H ₈ —), an octane group (—C ₈ H ₁₆ -), decane group (-C ₁₀ H ₂₀ -), methyleneoxy methylene _{(-CH 2 -O-CH 2 -} ), ethylene oxymethylene group _{(-C 2 H 4 -O-CH} 2 -), Propyleneoxymethylene group (—C ₃ H ₆ —O—CH—), Butyleneoxymethylene group (—C ₄ H ₈ —O—CH ₂ —), Propyleneoxyethylene group (—C ₃ H ₆ —OC ₂ H ₄₎ -), propylene oxypropylene group _{(-C 3 H 6 -OC 3 H} 6 -) and the like.

  The mixing ratio of the alkoxysilane having a silica structure and the alkoxysilane having a glycidyl group and an organic chain X is 10 to 50 parts by mass of the alkoxysilane having a silica structure when the total of both is 100 parts by mass. The alkoxysilane having a group and an organic chain X is preferably the remainder (90 to 50 parts by mass). More preferably, the alkoxysilane having a silica structure is 25 to 45 parts by mass, and the alkoxysilane having a glycidyl group and the organic chain X is the remainder (75 to 55 parts by mass).

  When the mixing ratio of the alkoxysilane having a silica structure is less than 10 parts by mass, the hardness of the formed hydrophilic film becomes too low, and the abrasion resistance and durability of the hydrophilic film become insufficient. As the hardness of the hydrophilic film, a pencil hardness of 2H or more is required from the viewpoint of the abrasion resistance and durability of the hydrophilic film. On the other hand, when the mixing ratio of the alkoxysilane having the glycidyl group and the organic chain X is less than 50 parts by mass, the effect of improving hydrophilicity cannot be sufficiently obtained.

(3) Amine having a hydroxy group The amine having a hydroxy group used in the present invention is a compound for supplying and unevenly distributing a hydrophilic group on the surface of a hydrophilic film, and the amino group is a primary or secondary amino group. A compound having at least one hydroxy group is preferable. By combining the amino group and the previous glycidyl group, the hydroxy group resulting from ring opening of the glycidyl group and the hydroxy group of the present amine can be unevenly distributed on the surface of the hydrophilic film. From the viewpoint of improving hydrophilicity, an amine having two or more hydroxy groups is more preferable.

  In addition, the amine may or may not have an aromatic ring in the molecular structure. An amine having an aromatic ring in the molecular structure (particularly an amine in which an amino group is directly bonded to the aromatic ring) is more hydrophobic than an amine having no aromatic ring in the molecular structure. It tends to be unevenly distributed on the layer side (near the film surface), and has the effect of further improving the hydrophilicity of the film after the curing reaction. However, an amine having an aromatic ring in the molecular structure requires a higher reaction temperature than an amine having no aromatic ring in the molecular structure in the film curing reaction. Therefore, when the transparent substrate forming the hydrophilic film is made of a material with relatively low heat resistance (for example, a resin material with low heat resistance), it has an aromatic ring in the molecular structure as an amine having a hydroxy group. It is preferable to use an amine that does not.

  Examples of amines that do not have an aromatic ring in the molecular structure and have one hydroxy group include monoethanolamine, 2- (2-aminoethoxy) ethanol, 1-amino-2-propanol, 2-amino-1- Propanol, 1-amino-2-butanol, 2-amino-1-butanol, 2-aminocyclohexanol, 3-aminocyclohexanol, 4-aminocyclohexanol, 4-aminocyclohexanoethanol, 4-amino-1-butanol 5-amino-1-pentanol, 6-amino-1-hexanol, 8-amino-1-octanol, 10-amino-1-decanol, 12-amino-1-dodecanol, 4- (2-aminoethyl) And cyclohexanol.

  Examples of amines that do not have an aromatic ring in the molecular structure and have two hydroxy groups include diethanolamine, 2-amino-1,3-propanediol, and 3-amino-1,2-propanediol.

  Examples of the amine having an aromatic ring in the molecular structure and one hydroxy group include 2-aminobenzyl alcohol, 3-aminobenzyl alcohol, 4-aminobenzyl alcohol, 2-aminophenol, 3-aminophenol, 4 -Aminophenol, 2-amino-4-bromophenol, 3-amino-4-bromophenol, 4-amino-2-bromophenol, 4-amino-3-bromophenol, 2-amino-3-cresol, 2- Amino-4-cresol, 3-amino-2-cresol, 4-amino-2-cresol, 4-amino-3-cresol, 5-amino-2-cresol, 6-amino-3-cresol, 2-amino- 4-fluorophenol, 2-amino-5-fluorophenol, 4-amino-2-fluorophenol, 4-amino-3-fluorophenol, 2'-amino-3'-hydroxyacetophenone, 1-amino-4-hydroxy Anthraquinone, 2- Amino-3-hydroxyanthraquinone, 2-amino-3-phenol, 2-amino-4-phenol, 2-amino-5-phenol, 4-amino-2-phenol, 4-amino-3-phenol, 2- ( 2-amino-1-phenyl) ethanol, 2- (4-amino-1-phenyl) ethanol, 2- (4-amino-1-phenyl) ethylamine, 3-amino-3-phenyl-1-propanol, 2- Examples include aniline ethanol and 3-anilino-1-propanol.

  Examples of the amine having an aromatic ring and two hydroxy groups in the molecular structure include 5-amino-N, N′-bis (2,3-dihydroxypropyl) isophthalamide, 3-aminophenylboronic acid. Is mentioned. Note that “—OH” in the molecular structure of an amine having a phenylboronic acid structure is not a hydroxy group in a strict chemical meaning, but is included in the amine in the present invention.

  As described above, since the amine having a hydroxy group is a compound for supplying and unevenly distributing a hydrophilic group on the surface of the hydrophilic film, it is slightly smaller than the alkoxysilane that forms the parent phase of the hydrophilic film. Mixing quantities is sufficient. Specifically, it is preferable to mix with a glycidyl group and an alkoxysilane having an organic chain X at a mass ratio of 1/500 to 1/100. When the mass mixing ratio is less than 1/500, the effect of improving hydrophilicity cannot be sufficiently obtained. On the other hand, even if the mass mixing ratio exceeds 1/100, the material cost is wasted because the effect is saturated.

(4) Solvent As the solvent used in the present invention, it is preferable to use a linear or branched lower alcohol (alcohol having 5 or less carbon atoms in the molecular structure). Further, the lower alcohol used as the solvent is preferably a liquid in a standard state (0 ° C., 1 atm) and having a boiling point of 140 ° C. or lower. For example, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 1-pentanol, 3-methyl-1-butanol, 2-methyl-2-butanol Is mentioned.

  These lower alcohols have a resin (for example, a solvent such as acetone or 2-butanone) or an ester solvent (for example, ethyl acetate or butyl acetate) or an ether solvent (for example, diethyl ether). Since the erosion property with respect to an acrylic resin, a polyethylene terephthalate resin, and a polycarbonate resin is low, it can be suitably used also for a resin translucent substrate. Furthermore, since the boiling point is low, it can be volatilized and removed quickly when the hydrophilic film is cured after coating. A small amount of ketone solvent, ester solvent, or ether solvent may be added and mixed for the purpose of promoting the volatilization removal of the alcohol solvent.

(5) Inorganic oxide particles Although not an essential constituent in the coating for hydrophilic films used in the present invention, in order to increase the hydrophilicity of the hydrophilic film, mixing chemically stable inorganic oxide fine particles is not possible. preferable. As the inorganic oxide to be mixed, an inorganic oxide that is colorless and transparent in the visible light region and has a refractive index equivalent to that of a hydrophilic film or a light-transmitting substrate is preferable so as not to inhibit light transmission. For example, silica (SiO ₂ ) can be preferably used.

  The average particle size of the inorganic oxide particles to be mixed is preferably 5 nm or more and 15 nm or less. When the average particle size exceeds 15 nm, the surface smoothness of the hydrophilic film decreases (surface roughness increases), which causes scattering of incident light (hydrophobic white turbidity). On the other hand, when the average particle size is less than 5 nm, the cohesiveness between particles becomes strong and it becomes easy to form large secondary particles, resulting in the same problem as when the average particle size is too large.

  The mixing ratio of the inorganic oxide particles to the coating for the hydrophilic film is preferably adjusted so that the arithmetic average roughness Ra of the surface of the formed hydrophilic film is 10 nm or less. For example, it is preferable to mix inorganic oxide particles at 1.2 parts by mass or less with respect to 100 parts by mass of the coating for hydrophilic film. When the arithmetic average roughness Ra of the hydrophilic film surface exceeds 10 nm, it becomes a scattering factor of incident light.

(Hydrophilic film forming process)
A hydrophilic film forming step of forming the hydrophilic film 20 on the translucent substrate 10 is performed using the hydrophilic film coating material prepared above. The hydrophilic film forming process includes a paint application process for applying a hydrophilic film paint on the translucent substrate and a film curing reaction process for heating the applied coating film to advance a film curing reaction.

  In the paint application process, there is no particular limitation on the method for applying the hydrophilic film paint, and conventional methods (for example, dip coating, spray coating, spin coating) can be used.

  The film curing reaction step is a characteristic part in producing the light-transmitting member with a hydrophilic film of the present invention. FIG. 3A is a chemical structure schematic diagram showing an example of the previous stage of the film curing reaction in the film curing reaction process. FIG. 3A shows a case where diethanolamine is used as the amine having a hydroxy group in the hydrophilic film coating material as in FIG. 1 (the same applies to FIG. 3B).

  When the coating film is heated, first, as shown in FIG. 3A, two types of alkoxysilanes (alkoxysilane having a silica structure, alkoxysilane having a glycidyl group and an organic chain X) are polymerized and formed on the translucent substrate 10. An amorphous silica film 21 is formed (alkoxylane polymer process). At this time, the alkoxysilane having the glycidyl group and the organic chain X and the amine having the hydroxy group are more hydrophobic than the translucent substrate 10 and the amorphous silica film 21, and therefore the air layer of the coating film It tends to be unevenly distributed on the side (that is, the surface side of the coating film). In other words, the amorphous silica film 21 is formed so that glycidyl groups are unevenly distributed in the surface region of the coating film.

  FIG. 3B is a chemical structure schematic diagram showing an example of a later stage of the film curing reaction in the film curing reaction element process. As shown in FIG. 3B, when the solvent is volatilized and the curing reaction proceeds, the glycidyl group that is unevenly distributed in the surface region of the coating film and the amino group of diethanolamine are combined (glycidyl group-amino group compound process). Since this compound is a chemical reaction for ring opening of the glycidyl group, in addition to the hydroxy group originally possessed by diethanolamine, a hydroxyalkyleneamino group 22 is newly generated in the form of a hydroxy group resulting from the ring opening of the glycidyl group. Form. As a result, more hydroxy groups can be unevenly distributed in the surface region of the hydrophilic film 20, and the hydrophilicity of the hydrophilic film 20 can be increased (see FIG. 1).

  FIG. 4 is a chemical structure schematic diagram showing another example of the later stage of the film curing reaction in the film curing reaction element process. FIG. 4 shows a case where 4-aminobenzyl alcohol is used as the amine having a hydroxy group in the hydrophilic film paint, as in FIG.

  As shown in FIG. 4, when the coating curing reaction proceeds, glycidyl groups that are unevenly distributed on the surface area of the coating and amino groups of 4-aminobenzyl alcohol combine (glycidyl group-amino group compound process). . As a result, in addition to the hydroxy group that 4-aminobenzyl alcohol originally has, a hydroxyalkyleneamino group 22 'is formed in the form of a new hydroxy group resulting from ring opening of the glycidyl group. Therefore, more hydroxy groups can be unevenly distributed in the surface region of the hydrophilic film 20, and the hydrophilicity of the hydrophilic film 20 can be increased (see FIG. 2).

[In-vehicle camera using translucent member with hydrophilic film]
FIG. 5 is a schematic cross-sectional view showing an example of an in-vehicle camera provided with a transparent member with a hydrophilic film according to the present invention. As shown in FIG. 5, in the in-vehicle camera 200 according to the present invention, a translucent member 100 with a hydrophilic film is attached to a camera housing 32 via a packing 31. In addition, an image element 33 (for example, a CCD image sensor) is disposed inside the camera housing 32 so as to capture image information that has entered through the transparent member 100 with a hydrophilic film. Is transmitted to an image processing apparatus (not shown).

  The in-vehicle camera 200 is equipped with a transparent film 100 with a hydrophilic film that has higher hydrophilicity than before, so it is possible to quickly form a water film even at the initial stage of moisture adhesion to the surface of the transparent film In order to suppress the formation of water droplets, a clear image without disturbance can be captured. That is, it is possible to provide an in-vehicle camera that is less affected by weather conditions than before.

  According to the study by the present inventors, when the distance between the translucent member 100 with a hydrophilic film and the image element 33 is about 4 mm, the amount of light received by the image element 33 is smaller than when the distance is 3 mm. Decreased by about 2%. On the other hand, when the distance between the translucent member 100 with the hydrophilic film and the image element 33 is 3 mm, the amount of light received by the image element 33 is about 0.5% lower than when the distance is 0 mm. . From such a result, in the in-vehicle camera 200, the distance between the transparent member 100 with the hydrophilic film and the image element 33 is preferably 3 mm or less.

  Further, in this specification, the in-vehicle camera 200 has been described in the image of an in-vehicle camera for an automobile, but the in-vehicle camera 200 of the present invention is not limited to an automobile. For example, it may be an in-vehicle camera for a construction machine vehicle, an in-vehicle camera for a railway vehicle, an in-vehicle camera for a cableway vehicle, or an in-vehicle camera for an aircraft. Also good.

  Next, the present invention will be described more specifically with reference to examples and comparative examples. The present invention is not limited to these examples.

[Experiment 1]
(1-1) Preparation of coating material for hydrophilic film Tetraethoxysilane (20 parts by mass) was dissolved in ethanol (980 parts by mass), a very small amount of nitric acid was added, and the mixture was heated at 50 ° C for 1 hour. Thereby, a silica sol solution (1000 parts by mass) having a silica concentration of about 2% by mass after the film curing reaction was prepared. This solution becomes a solution (referred to as solution a) containing an alkoxysilane having a silica structure.

  3-glycidoxypropyltrimethoxysilane (2 parts by mass) was dissolved in ethanol (98 parts by mass). This solution becomes a 2% by mass solution of alkoxysilane having a glycidyl group and an organic chain X (referred to as solution b).

  Diethanolamine (2 parts by mass) was dissolved in ethanol (98 parts by mass). This solution becomes a 2% by mass solution of an amine having a hydroxy group (referred to as solution c).

  The above-mentioned solutions a to c were mixed at a ratio shown in Table 1 described later to prepare hydrophilic film paints A to H.

(1-2) Preparation of translucent member with hydrophilic film and evaluation of hydrophilic film As a translucent base material, an acrylic resin (PMMA) flat plate and an acrylic resin convex lens are prepared, and on the translucent base material, for a hydrophilic film Coating materials A to H were applied by a spin coating method (2500 rpm, 30 seconds). Thereafter, the coated light-transmitting substrate was heated at 80 ° C. for 60 minutes to cause solvent volatilization and film curing reaction to form a hydrophilic film, thereby preparing a light-transmitting member with a hydrophilic film.

  FIG. 6 is a cross-sectional SEM observation image showing a transparent member with a hydrophilic film prepared using the coating material D for hydrophilic film. As shown in FIG. 6, it can be seen that a smooth hydrophilic film is formed on the translucent substrate. The arithmetic average roughness Ra of the hydrophilic film surface was measured and found to be about 3 nm.

  As the hydrophilicity evaluation of the obtained hydrophilic film, the contact angle with water on the hydrophilic film surface was measured. In addition, for a sample using an acrylic resin flat plate as a light-transmitting substrate, the pencil hardness of the hydrophilic film was measured as an evaluation of the abrasion resistance and durability of the hydrophilic film. The results are also shown in Table 1.

  In this experiment, since it was difficult to accurately measure a contact angle of less than 10 °, all cases where the contact angle was less than 10 ° were described as “<10 °”. Further, since it is said that the pencil hardness of 5H is sufficient for the abrasion resistance / durability of the hydrophilic film, all cases where the pencil hardness of 5H is passed are described as “5H ≦”. The same applies to the subsequent experiments.

  As shown in Table 1, it was confirmed that the hydrophilic film formed with the hydrophilic film paints A to D has a contact angle with water of less than 10 ° and exhibits high hydrophilicity. Further, it was found that the hydrophilic film formed with the coatings C to H for the hydrophilic film has a pencil hardness of 5H or more and has high abrasion resistance and durability. That is, it was found that the hydrophilic film formed with the coatings A to D for the hydrophilic film satisfies both the hydrophilicity and the scuff resistance / durability at the same time.

[Experiment 2]
(2-1) Preparation of hydrophilic film paint Silica particles (average particle diameter 10 nm) were mixed with the hydrophilic film paint E (100 parts by mass) prepared in Experiment 1 in the ratio of Table 2 described later. The coatings IL for hydrophilic films were prepared.

(2-2) Production of light-transmitting member with hydrophilic film and evaluation of hydrophilic film Prepare the same acrylic resin flat plate as in Experiment 1 as the light-transmitting substrate, and apply the coatings I to L for the hydrophilic film on the light-transmitting substrate. In the same manner as in Experiment 1, a hydrophilic film was formed, and a transparent member with a hydrophilic film was produced.

  FIG. 7 is a cross-sectional SEM observation image showing a transparent member with a hydrophilic film produced using the coating J for hydrophilic film. As shown in FIG. 7, it can be seen that a hydrophilic film containing silica particles is formed on the translucent substrate. The arithmetic average roughness Ra of the hydrophilic film surface was measured and found to be about 9 nm.

  As an evaluation of the hydrophilicity of the obtained hydrophilic film, the contact angle with water on the surface of the hydrophilic film was measured in the same manner as in Experiment 1. Further, as an evaluation of the translucency of the hydrophilic film, the arithmetic average roughness Ra of the hydrophilic film surface and the light transmittance at a wavelength of 400 nm in the translucent member with the hydrophilic film were measured. The results are also shown in Table 2.

  As shown in Table 2, the hydrophilic film formed with the hydrophilic film paints I to L had a contact angle with water of less than 10 °. Compared to the base coating E for hydrophilic film, the contact angle with water was reduced from 25 ° to less than 10 °, and it was confirmed that the hydrophilicity of the hydrophilic film was improved by mixing silica particles.

  On the other hand, it was found that by mixing silica particles, the arithmetic average roughness Ra of the hydrophilic film surface increases and the light transmittance decreases. This is presumably because the incident light was scattered by the increase in the surface roughness of the hydrophilic film and the light transmittance was lowered.

  The surface arithmetic average roughness and light transmittance of the acrylic resin flat plate as a light transmissive substrate were separately measured and found to be about 3 nm and 92%, respectively. Comparing the results of the acrylic resin flat plate with the results shown in Table 2, it is possible to mix silica particles in the range where the arithmetic average roughness Ra of the hydrophilic film surface is 10 nm or less from the viewpoint of hydrophilicity and light transmittance. It was confirmed that it was preferable.

  Here, considering the results of Experiments 1 and 2, the mixing ratio of the two types of alkoxysilanes in the hydrophilic film paint (mixing ratio of alkoxysilane having a silica structure and alkoxysilane having a glycidyl group and an organic chain X) Is expressed as “a / (a + b)” in Experiment 1, “10% ≦ a / (a + b) ≦ 50%” is preferable, and “25% ≦ a / (a + b) ≦ 45%” is more preferable. confirmed.

[Experiment 3]
(3-1) Preparation of paint for hydrophilic film 4-Aminobenzyl alcohol (2 parts by mass) was dissolved in ethanol (98 parts by mass) as an amine having a hydroxy group. This solution becomes a 2% by mass solution of an amine having an aromatic ring in the molecular structure (referred to as solution d).

  The solutions a to b of Experiment 1 and the solution d were mixed at a ratio shown in Table 3 to be described later to prepare hydrophilic film paints M to R.

(3-2) Preparation of translucent member with hydrophilic film and evaluation of hydrophilic film As a translucent base material, a silica glass flat plate and a silica glass convex lens are prepared, and on these translucent base materials, a coating M for hydrophilic film M ~ R was applied by spin coating (2500 rpm, 30 seconds). Thereafter, the coated translucent substrate was heated at 130 ° C. for 60 minutes to cause solvent volatilization and film curing reaction to form a hydrophilic film, thereby producing a translucent member with a hydrophilic film.

  As in Experiment 1, as an evaluation of the hydrophilicity of the obtained hydrophilic film, the contact angle with water on the surface of the hydrophilic film was measured, and as an evaluation of the abrasion resistance and durability of the hydrophilic film, the pencil hardness of the hydrophilic film was measured. It was measured. The results are also shown in Table 3.

  As shown in Table 3, it was confirmed that the hydrophilic film formed with the hydrophilic film paints MP has a contact angle with water of less than 10 ° and exhibits high hydrophilicity. Further, it was found that the hydrophilic film formed with the coatings O to R for the hydrophilic film has a pencil hardness of 5H or more and has high abrasion resistance and durability. In other words, it was found that the hydrophilic film formed of the coatings for hydrophilic films M to P satisfies both the hydrophilicity and the scuff resistance / durability at the same time.

  Since 4-aminobenzyl alcohol used in Experiment 3 has an aromatic ring in the molecular structure, it is considered to be more hydrophobic than diethanolamine used in Experiment 1. Therefore, 4-aminobenzyl alcohol tends to be unevenly distributed on the air layer side (near the membrane surface) when forming the hydrophilic film, and the hydrophilic film of Experiment 3 is expected to exhibit higher hydrophilicity than the hydrophilic film of Experiment 1. .

[Experiment 4]
(4-1) Preparation of translucent base material A lanthanum-boron glass convex lens is used as the translucent base material, a base material obtained by sputtering a silica film (thickness: 50 nm) on the surface of the glass lens, and a single glass lens Two types of base materials were prepared.

(4-2) Production and Evaluation of Translucent Member with Hydrophilic Film The hydrophilic film coating material A prepared in Experiment 1 was applied to the above two types of translucent substrates by spin coating (2500 rpm, 30 seconds). . Thereafter, the coated translucent substrate was heated at 100 ° C. for 60 minutes to cause solvent volatilization and film curing reaction to form a hydrophilic film, thereby producing a translucent member with a hydrophilic film. A sample in which a hydrophilic film is formed on a substrate obtained by sputtering a silica film on the surface of a glass lens is referred to as a translucent member S, and a sample in which a hydrophilic film is directly formed on a glass lens substrate is referred to as a translucent member T. Called.

  As an evaluation of the weather resistance of the obtained translucent member with a hydrophilic film (translucent member S, translucent member T), an accelerated weathering test method (JIS B 7753) was conducted (commonly known as a SWOM test), The contact angle measurement similar to Experiment 1 and the light transmittance measurement similar to Experiment 2 were performed.

  As a result, in the contact angle measurement, there was no particular change before and after the SWOM test in any sample, and it was confirmed that the formed hydrophilic film had practically sufficient weather resistance. On the other hand, in the light transmittance measurement, no particular change was observed in the light transmissive member S, but in the light transmissive member T, the light transmittance clearly decreased after the SWOM test. This was considered because the glass lens base material of the translucent member T was eroded by the SWOM test. In other words, when using a material with high ion binding property as the light-transmitting substrate, it was confirmed that it is preferable to form a weather resistant film made of silica or the like between the hydrophilic film and the light-transmitting substrate.

  The above-described embodiments and examples are specifically described in order to help understanding of the present invention, and the present invention is not limited to including all the configurations described. For example, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Furthermore, a part of the configuration of each embodiment can be deleted, replaced with another configuration, or added with another configuration.

100, 100 '... light-transmitting member with a hydrophilic film, 10 ... light-transmitting substrate, 20, 20' ... hydrophilic film,
21 ... Amorphous silica film, 22,22 '... hydroxyalkyleneamino group,
200: in-vehicle camera, 31: packing, 32: camera housing, 33: image element.

Claims (14)

A transparent member with a hydrophilic film in which a hydrophilic film is formed on the surface of the transparent substrate,
The hydrophilic film has amorphous silica as a parent phase, and a hydroxyalkyleneamino group is bonded to a surface region of the parent phase via an organic chain X,
The translucent member with a hydrophilic film, wherein the organic chain X is an alkylene chain or an alkyleneoxyalkylene chain. In the translucent member with a hydrophilic film according to claim 1,
The translucent member with a hydrophilic film, wherein the hydroxyalkyleneamino group is a secondary or tertiary amino group. In the translucent member with a hydrophilic film according to claim 1 or 2,
The translucent member with a hydrophilic film, wherein the hydroxyalkyleneamino group has an aromatic ring, and the amino group is directly bonded to the aromatic ring. In the translucent member with a hydrophilic film in any one of Claims 1 thru | or 3,
A transparent member with a hydrophilic film, wherein the hydrophilic film has a surface arithmetic average roughness of 10 nm or less. In the translucent member with a hydrophilic film in any one of Claims 1 thru | or 4,
The hydrophilic film further includes silica particles having an average particle diameter of 5 nm or more and 15 nm or less. In the translucent member with a hydrophilic film in any one of Claims 1 thru | or 5,
A light-transmitting member with a hydrophilic film, wherein a film made of silica or alumina is further formed between the hydrophilic film and the light-transmitting substrate. In the translucent member with a hydrophilic film in any one of Claims 1 thru | or 6,
A translucent member with a hydrophilic film, wherein a contact angle between the hydrophilic film and water is less than 10 °. In the translucent member with a hydrophilic film according to claim 7,
A light-transmitting member with a hydrophilic film, wherein the hydrophilic film has a pencil hardness of 5H or more. A method for producing a translucent member with a hydrophilic film in which a hydrophilic film is formed on the surface of the translucent substrate,
The hydrophilic film has amorphous silica as a parent phase, and a hydroxyalkyleneamino group is bonded to a surface region of the parent phase via an organic chain X,
The organic chain X is an alkylene chain or an alkyleneoxyalkylene chain,
The manufacturing method comprises preparing a hydrophilic film paint comprising an alkoxysilane having a silica structure, an alkoxysilane having a glycidyl group and the organic chain X, an amine having a hydroxy group, and a lower alcohol. Process,
A hydrophilic film forming step of forming the hydrophilic film using the hydrophilic film paint,
The hydrophilic film forming step includes a paint application step of applying the hydrophilic film paint to the surface of the light-transmitting substrate, and a film curing reaction step of heating the applied coating film to advance the curing reaction of the hydrophilic film. The manufacturing method of the translucent member with a hydrophilic film characterized by including this. In the manufacturing method of the translucent member with a hydrophilic film according to claim 9,
In the film curing reaction step, the alkoxysilane having the silica structure and the alkoxysilane having the glycidyl group and the organic chain X are polymerized to form an amorphous silica film on the translucent substrate. A polymer process,
A method for producing a translucent member with a hydrophilic film, comprising a glycidyl group-amino group compound process in which the glycidyl group and the amino group of the amine are combined. In the manufacturing method of the translucent member with a hydrophilic film according to claim 9 or 10,
The coating material for hydrophilic film comprises an alkoxysilane having the silica structure when the mixing ratio of the alkoxysilane having the silica structure and the alkoxysilane having the glycidyl group and the organic chain X is 100 parts by mass. A method for producing a light-transmitting member with a hydrophilic film, comprising silane in an amount of 10 to 50 parts by mass. In the manufacturing method of the translucent member with a hydrophilic film in any one of Claims 9 thru | or 11,
The method for producing a translucent member with a hydrophilic film, wherein the coating material for a hydrophilic film further contains silica particles having an average particle diameter of 5 nm or more and 15 nm or less. In the manufacturing method of the translucent member with a hydrophilic film in any one of Claims 9 thru | or 12,
A method for producing a translucent member with a hydrophilic film, further comprising a translucent base material preparation step of forming a silica film or an alumina film on the surface of the translucent base material. An in-vehicle camera disposed on the outer periphery of the vehicle,
The in-vehicle camera, wherein the in-vehicle camera is a translucent member with a hydrophilic film according to any one of claims 1 to 8.

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