Anti-fogging agent and anti-fogging method for vehicle lamp structure

Abstract

Provided is an anti-fogging agent is such that when a film of water is formed on a main surface of a base material that has been treated with the anti-fogging agent, the water film uniformity index WE expressed by formula (a) is 65% or higher. Equation (a): WE=(S / TS)×100 (In equation (a), TS represents the sum of the frequencies in an area distribution expressing the frequencies of the respective surface areas of black regions generated from an evaluation image having a size of 1824×1824 pixels obtained by imaging a subject having a checkerboard pattern including black squares and white squares having a side length of 0.5 mm through the base material on which a film of water has been formed, S represents the sum of the frequencies within in a predetermined surface area range of the area distribution, and the predetermined surface area range is a surface area range in which the frequency is at least 5% of the sum of the frequencies in the area distribution expressing the frequencies of the respective surface areas of black regions generated from a reference image having a size of 1824×1824 pixels obtained by imaging the subject through the base material., with the caveat that the distance between the subject and the base material is 2.5 cm, and the position of a digital camera imaging the subject is set so that 4900 black squares and white squares are included in the image having a size of 1824×1824 pixels.)

Description

Technical Field

[0001] The present invention relates to an anti-fogging agent and a method for preventing fogging of a vehicle lamp structure.

Background Art

[0002] A method of applying an anti-fogging agent composition containing a surfactant to the lamp chamber of a vehicle lamp structure such as an automobile, where there is a risk of fogging due to condensation, is known (see, for example, Patent Document 1). When moisture adheres to the coating film formed by the anti-fogging agent containing a surfactant, the moisture instantaneously forms a water film due to the effect of the surfactant, and the occurrence of fogging is suppressed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, recently, in an automobile headlight system, a method of controlling the lighting and extinguishing of a light source partially so as not to dazzle the drivers of oncoming vehicles or preceding vehicles has been adopted.

[0005] When such an anti-fogging agent is applied to a headlight, the formation of a water film on the treated surface by the anti-fogging agent can suppress the occurrence of fogging. However, from the viewpoint of making the above control function more effectively, it has been found that there is still room for further improvement in enhancing the uniformity of the water film in the anti-fogging agent. If the uniformity of the formed water film is low, the straightness and intensity of the transmitted light will be impaired, and there is a concern that the directivity and brightness of the light will decrease, and the area where the light is to be turned off (the area where no light is applied) will become blurred or distorted.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide an anti-fogging agent that is excellent in anti-fogging property and can sufficiently maintain the straightness and intensity of light transmitted when a water film is formed, and an anti-fogging method for a vehicle lamp structure using the same.

Means for Solving the Problems

[0007] One aspect of the present invention relates to an anti-fogging agent, wherein the water film uniformity index WE represented by the following formula (a) is 65% or more when a water film is formed on the main surface treated with the anti-fogging agent of the substrate. WE = (S / TS) × 100 …(a) [In formula (a), TS represents the total of the area and frequency of the black regions in the area distribution indicating the area and frequency of the black regions generated from an evaluation image of 1824 × 1824 pixels in size obtained by imaging a subject having a checkered pattern composed of a black square and a white square with a side length of 0.5 mm through the substrate on which the water film is formed. S represents the total of the frequencies included in a predetermined area range in the area distribution. The predetermined area range represents the area range in which the frequency is 5% or more of the total frequency in the area distribution indicating the area and frequency of the black regions generated from a reference image of 1824 × 1824 pixels in size obtained by imaging the subject through the substrate. However, the distance between the subject and the substrate is 2.5 cm, and the position of the digital camera for photographing the subject is set such that 4900 black squares and white squares are included in the image of 1824 × 1824 pixels in size.]

[0008] The anti-fogging agent with the water film uniformity index WE of 65% or more is excellent in anti-fogging property and can sufficiently maintain the straightness and intensity of light transmitted when a water film is formed.

[0009] The above anti-fogging agent may have an anti-fogging index AFI represented by the following formula (b) of 7 or more when water vapor is brought into contact with the main surface treated with the anti-fogging agent of the substrate. AFI = (S1 - S2) × 10 / (S0 - S2) …(b) [In formula (b), S1 represents the file size when the anti-fogging evaluation image obtained by imaging the above-described subject through the above-described base material contacted with water vapor is compressed by a predetermined compression method, S2 represents the file size when the image N obtained by imaging the above-described subject through the untreated base material contacted with water vapor is compressed by the above-described predetermined compression method, and S0 represents the file size when the image O obtained by imaging the above-described subject through the untreated base material is compressed by the above-described predetermined compression method. However, the sizes of the anti-fogging evaluation image, the image N, and the image O are 1824×1824 pixels, the distance between the subject and the base material is 2.5 cm, and the above-described predetermined compression method refers to compressing at a compression rate of 20% and resizing to 820×820 pixels.]

[0010] The above anti-fogging agent may contain colloidal silica, at least one selected from the group consisting of a cross-linking agent, a binder, and a metal chelate, and a liquid medium.

[0011] One aspect of the present invention relates to an anti-fogging method for a vehicle lamp structure, in which the inner surface of the lens included in the vehicle lamp structure is treated with the above anti-fogging agent. According to this method, it is possible to impart anti-fogging properties to the vehicle lamp structure and form an anti-fogging film that can sufficiently maintain the straightness and intensity of the light transmitted when a water film is formed.

Effects of the Invention

[0012] According to the present invention, it is possible to provide an anti-fogging agent having excellent anti-fogging properties and capable of sufficiently maintaining the straightness and intensity of the light transmitted when a water film is formed, and an anti-fogging method for a vehicle lamp structure using the same.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0014] Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings as appropriate. However, the present invention is not limited to the following embodiments. The materials exemplified below may be used alone or in combination of two or more unless otherwise specified. The content of each component in the composition means the total amount of the plurality of substances corresponding to each component in the composition when there are a plurality of substances corresponding to each component in the composition, unless otherwise specified. The numerical range indicated by using "~" indicates a range including the numerical values described before and after "~" as the minimum value and the maximum value, respectively. In the numerical ranges described stepwise in this specification, the upper limit value or the lower limit value of a certain step's numerical range may be replaced with the upper limit value or the lower limit value of another step's numerical range. In the numerical ranges described in this specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.

[0015] <Antifogging agent> The antifogging agent of this embodiment has a water film uniformity index WE represented by the following formula (a) of 65% or more when a water film is formed on the main surface treated with the antifogging agent of the base material. WE = (S / TS) × 100 …(a) [In formula (a), TS represents the total frequency in the area distribution showing the area and frequency of the black regions generated from an evaluation image of size 1824×1824 pixels obtained by imaging a subject having a checkered pattern composed of black and white squares with a side length of 0.5 mm through the above-mentioned substrate on which a water film is formed. S represents the total frequency included in a predetermined area range in the above area distribution. The predetermined area range represents the area range in which the frequency is 5% or more of the total frequency in the area distribution showing the area and frequency of the black regions generated from a reference image of size 1824×1824 pixels obtained by imaging the above subject through the above substrate. However, the distance between the above subject and the above substrate is 2.5 cm, and the position of the digital camera for photographing the above subject is set such that 4900 black and white squares are included in an image of size 1824×1824 pixels.]

[0016] Further, the anti-fogging agent of the present embodiment may have an anti-fogging index AFI represented by the following formula (b) of 7 or more when water vapor is brought into contact with the main surface treated with the anti-fogging agent of the substrate. AFI = (S1 - S2) × 10 / (S0 - S2) …(b) [In formula (b), S1 represents the file size when the anti-fogging property evaluation image obtained by imaging the above subject through the above substrate in contact with water vapor is compressed by a predetermined compression method. S2 represents the file size when the image N obtained by imaging the above subject through the untreated substrate in contact with water vapor is compressed by the above predetermined compression method. S0 represents the file size when the image O obtained by imaging the above subject through the untreated substrate is compressed by the above predetermined compression method. However, the sizes of the anti-fogging property evaluation image, the image N, and the image O are 1824×1824 pixels, the distance between the above subject and the above substrate is 2.5 cm, the position of the digital camera for photographing the above subject is set such that 4900 black and white squares are included in an image of size 1824×1824 pixels, and the above predetermined compression method refers to compressing at a compression rate of 20% and resizing to 820×820 pixels.]

[0017] A method for calculating the water film uniformity index WE and the anti-fogging index AFI will be described in detail.

[0018] <Water film uniformity index WE> The water film uniformity index WE can be obtained by the following method. First step: Prepare a sample in which the main surface of the substrate is treated with an anti-fogging agent. Second step: Image a subject having a pattern in which a plurality of regions having a predetermined luminance are arranged in a predetermined area (hereinafter, also referred to as a "sample image") through a sample in which a water film is formed on the main surface treated with the anti-fogging agent to obtain an evaluation image. Third step: Derive a water film uniformity index indicating the uniformity of the water film based on the area distribution of the regions having a predetermined luminance in the evaluation image.

[0019] (First step) FIG. 1 is a schematic diagram for explaining a method for calculating the water film uniformity index WE and the anti-fogging index AFI, and shows an example of a method for preparing a sample in the first step. (A) of FIG. 1 shows a step (coating step) of forming a coating film by spraying an anti-fogging agent 2 onto the main surface S1 of the substrate 1 with a spray 3. (B) of FIG. 1 shows a sample 10 obtained by drying the coating film. The sample 10 has a film (hereinafter, also referred to as an "anti-fogging film") 5 formed from an anti-fogging agent on the main surface S1 of the substrate 1.

[0020] When calculating the water film uniformity index WE and the anti-fogging index AFI, a polycarbonate substrate can be used as the substrate 1. The thickness of the substrate 1 can be 2 mm.

[0021] The size of the substrate 1 can be 10 cm square so that a sufficient number of pixels can be obtained in the evaluation image.

[0022] The substrate 1 can have a visible light transmittance of 85% or more. The visible light transmittance of the substrate can be measured, for example, with a U-3500 type recording spectrophotometer (manufactured by Hitachi, Ltd.).

[0023] The base material 1 can have a haze of 1.0 or less. The haze of the base material can be measured, for example, by a haze meter (NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0024] The base material 1 can have a YI of 1.5 or less. The YI of the base material 1 can be measured, for example, by a colorimeter (300A, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0025] The main surface S1 of the base material 1 has not been treated with anything other than the anti-fogging agent (untreated) and can be washed with isopropyl alcohol.

[0026] Figure 1 shows the case where the treatment with the anti-fogging agent is by spraying and drying after coating, but the treatment method can be appropriately selected according to practical use.

[0027] The coating method of the anti-fogging agent may be a spin coating method, a dip coating method, a flow coating method, a bar coating method, a gravure coating method, or the like.

[0028] The coating amount is not limited because it depends on the components of the anti-fogging agent, its content, etc., but for example, it can be 10 -9 ~10 3 g / m 2 and can be set as such.

[0029] The temperature of the anti-fogging agent used in the coating process may be, for example, 1 to 50 °C, or may be 10 to 30 °C. The coating time of the anti-fogging agent can be, for example, 1 second to 1 hour, and can be 5 to 30 minutes.

[0030] The drying temperature may be, for example, 5 to 300 °C, or may be 10 to 200 °C. The drying time can be 30 seconds to 150 hours.

[0031] When calculating the water film uniformity index WE and the anti-fogging index AFI, the thickness of the anti-fogging film 5 can be set to 1 μm. The film thickness of the anti-fogging film can be measured, for example, using a non-contact film thickness gauge, Optical NanoGauge C13027 (manufactured by Hamamatsu Photonics K.K.). The above-mentioned coating amount, coating temperature, coating time, drying temperature, and drying time can be appropriately set so that the thickness of the anti-fogging film 5 falls within the above range.

[0032] (Second Step) FIG. 2 shows an example of an apparatus for obtaining an evaluation image in the second step. In the apparatus shown in FIG. 2, water 20 is placed in a water bath having an open upper surface and capable of temperature adjustment, and a sample image 30 is placed at a position with a depth D2 from the water surface, with the surface S2 having a pattern facing the water surface side. Further, above the water bath, a digital camera 40 is arranged facing the water surface side at a distance D3 from the surface S2 of the sample image 30.

[0033] The sample image 30 is a subject having a checkerboard pattern composed of black squares and white squares with a side length of 0.5 mm. FIG. 3 is a diagram showing the sample image. The image shown in FIG. 3 is a checkerboard pattern in which black squares and white squares are arranged alternately vertically and horizontally, and black squares and white squares are provided. In this checkerboard pattern, the side length of the square is 0.5 mm, and its area is 0.25 mm 2 ². Also, the difference between the black squares and the white squares can be set such that when the reference image described later is converted to 8 bits of 0 to 255, the luminance difference between the two regions is 150 or more.

[0034] As the digital camera 40, one that can output an 8-bit numerical value of 0 to 255 for each pixel can be used.

[0035] The distance D3 between the digital camera 40 and the surface S2 of the sample image 30 can be set so that only the sample image is captured, and can be set to 17 cm. When using the sample image (a 0.5 mm × 0.5 mm square checkered pattern) shown in Fig. 3, the distance D3 can be set so that 4,900 squares are included in an image of size 1824 × 1824 pixels.

[0036] The sample image 30 is placed in water at a depth D2 from the water surface, and D2 can be set to 1 cm.

[0037] Although not shown in Fig. 2, the surface S2 of the sample image 30 can be illuminated using a light source so as to obtain an image with appropriate exposure.

[0038] In this embodiment, in order to form a water film on the main surface treated with the anti-fogging agent of the substrate, the sample 10 is arranged above the water bath at a distance D1 from the water surface of the water 20 so that the main surface S1 of the substrate faces the water surface.

[0039] The distance D1 between the main surface S1 and the water surface can be set to 1.5 cm.

[0040] When the sample 10 is arranged above the water bath, the water 20 may be heated to a predetermined temperature. A water film or fogging can be formed on the main surface treated with the anti-fogging agent of the substrate by water vapor (steam) generated from the water surface. In this specification, the water film means a film of water formed on the main surface treated with the anti-fogging agent of the substrate. The formation of the water film can be visually confirmed.

[0041] In the second step, the sample image 30 is captured through the sample on which the water film is formed. By checking in advance the time from when the sample 10 is arranged until the water film is formed, the imaging timing can be set using the passage of time as an index.

[0042] The time from when the sample 10 is placed until the water film is formed can be imaged 40 seconds after the start when the temperature of the water 20 is 40°C and the distance D1 is 1.5 cm.

[0043] (Third step) In the third step, a water film uniformity index indicating the uniformity of the water film is derived based on the area distribution of the black regions (corresponding to the black squares) in the evaluation image.

[0044] Figure 4 shows evaluation images with different water film uniformities. The evaluation image in (B) is an image when the water film uniformity is low, and it can be seen that there is a greater variation in the area of the black regions (corresponding to the black squares) than in the evaluation image in (A). Therefore, the uniformity of the water film can be measured based on the area distribution of the black regions in the evaluation image.

[0045] The water film uniformity index can be calculated by comparing the sample image with a reference image captured through the substrate in a state where no water film is formed. The reference image can be, for example, an image captured immediately after placing the substrate not treated with an anti-fogging agent (0 seconds after placement).

[0046] The water film uniformity index is derived by the following image processing from the evaluation image and the reference image obtained under the following imaging conditions using a sample image having a checkerboard pattern shown in Figure 3.

[0047] [Imaging conditions] Digital camera: Canon PowerShot SX70 HS (Focal length in 35mm film equivalent: 15 mm, Image size 1824×1824 pixels, Save format jpg)

[0048] [Image processing] (1) Using image processing software (ImageJ), load the evaluation image and the reference image and convert them to 8-bit (Image→type→8-bit). (2) Set the threshold of the boundary to "90 - 255" (Image → Adjust → Threshold → Set to "90 - 255" → apply). (3) Binarize it (Process → Binary → Make Binary). (4) Set "Area" as the measurement condition (Analyze → Set Measurements → Check Area). (5) Calculate the area of 1 pixel angle or more using particle analysis (Analyze → Analyze Particles → Set "Size" to "1 - Infinity", "Show" to "Outlines", check "Display results" and "Clear Results", and click OK). (6) From the information in (5) of the reference image, create a frequency distribution with an interval of 20 pixels in the range of 0 - 1000 pixels as the area distribution, and obtain the area range RA where the frequency is 5% or more of the total frequency. (7) From the information in (5) of the evaluation image, create a frequency distribution with an interval of 20 pixels in the range of 0 - 1000 pixels as the area distribution, calculate the ratio (%) of the number of particles (frequency) included in the area range in (6) to the total number of particles (total frequency), and use this as the water film uniformity index.

[0049] Figure 5 is a diagram showing an example of the area distribution created in (6) and (7) above. Note that the reference image and the evaluation image are images obtained by the method shown in Figure 2. The reference image is an image taken immediately after placing a substrate (polycarbonate plate) not treated with an anti - fogging agent (0 seconds after placement), and the evaluation image is an image taken 40 seconds after placing a sample obtained by applying an anti - fogging agent (here, one with low water film uniformity) to the polycarbonate plate and drying it. D1, D2, and D3 in Figure 2 are 1 cm, 1.5 cm, and 17 cm respectively, and the water temperature is 40°C.

[0050] The area range RA in the reference image is the range where the area is 300 - 400 pixels (the range indicated by B in Figure 5), and the water film uniformity index of the evaluation image is calculated to be 36%.

[0051] <Anti-fogging Index AFI> The anti-fogging index AFI can be obtained by the following method. Step 4: After bringing water vapor into contact with the main surface of the sample prepared in the above Step 1, image a predetermined subject through the sample to obtain an anti-fogging evaluation image. Step 5: Derive an anti-fogging index indicating the anti-fogging property of the anti-fogging agent based on the file capacity after compression when the anti-fogging evaluation image is compressed by a predetermined compression method.

[0052] (Step 4) The contact with water vapor can be performed by the apparatus shown in FIG. 2 described above. That is, the water temperatures of D1, D2, and D3, and water 20 in FIG. 2 can be set to the values described in Step 2. Further, by checking in advance the time from when the base material is placed until fogging is generated, the imaging timing can be set using the passage of time as an index. The time from when the base material is placed until fogging is generated depends on the type of the base material, the temperature of water 20, the distance D1, etc. However, when the base material is a polycarbonate plate, the temperature of water 20 is 40° C., and the distance D1 is 1.5 cm, imaging can be performed after 10 seconds have elapsed.

[0053] The anti-fogging evaluation image can be obtained by arranging the sample prepared in Step 1 as shown in FIG. 2 and imaging a sample image after a predetermined time has elapsed (for example, 10 seconds) that has been confirmed in advance.

[0054] For the sample image, the checkered pattern shown in FIG. 3 can be used. In this case, the distance D3 can be set so that 4900 squares are included in an image having a size of 1824×1824 pixels.

[0055] (Step 5) In Step 5, an anti-fogging index indicating the anti-fogging property of the anti-fogging agent is derived based on the file capacity after compression when the anti-fogging evaluation image obtained in Step 4 is compressed by a predetermined compression method.

[0056] Regarding the file size after compression, for example, when compressing a JPG image, the information of the parts that have turned white due to cloudiness is compressed, and the number of image files decreases. That is, due to the compression of the image, the parts that have turned white due to cloudiness lose their color gradation and are replaced with the average color, resulting in a decrease in the number of image files. On the other hand, since the information of the non-cloudy parts is difficult to compress, the number of image files remains high.

[0057] As compression methods, irreversible compression and resizing are used.

[0058] In this embodiment, when the file size when the anti-fog evaluation image is compressed by the above compression method is S1, the file size when the image N obtained by imaging the predetermined subject through the fogged substrate after contacting the untreated substrate with water vapor is compressed by the above compression method is S2, and the file size when the image O obtained by imaging the above subject through the untreated substrate is compressed by the above compression method is S0, the anti-fog index AFI calculated by the following formula can be used. AFI=(S1 - S2)×10 / (S0 - S2)

[0059] When calculating the above anti-fog index AFI, the imaging conditions and compression conditions of the anti-fog evaluation image, image N, and image O are to obtain a jpg image of size 1824×1824 pixels, compress this at a compression rate of 20% (compression level 20), and further resize it to 820×820 pixels.

[0060] Image O and image N can be obtained by arranging a substrate not treated with an anti-fog agent and imaging sample images immediately after arrangement (0 seconds after arrangement) and after a predetermined time has elapsed (for example, 10 seconds later). Also, S0 and S1 may be calculated in advance from these images.

[0061] The anti-fog agent of this embodiment may have a water film uniformity index WE of 65% or more, 70% or more, 80% or more, or 90% or more.

[0062] As a method for increasing the water film uniformity index WE of the anti-fogging agent, for example, combining colloidal silica described later with a specific colloidal silica binding material, increasing the hydrophilicity of the material, and increasing the smoothness of the coating film surface can be mentioned.

[0063] The anti-fogging agent of this embodiment may have an anti-fogging index AFI of 6.0 or more, 7.0 or more, or 8.0 or more.

[0064] As a method for increasing the anti-fogging index AFI of the anti-fogging agent, for example, increasing the amount of hydrophilic groups and adding hydrophilic materials can be mentioned.

[0065] The anti-fogging agent of this embodiment may be capable of forming a film having a contact angle with water of 10° or less, 8° or less, or 5° or less.

[0066] The contact angle can be calculated by using a contact angle meter, for example, as the average value of 10 measurements for a 1 μL droplet of ultrapure water.

[0067] The anti-fogging agent of this embodiment may be a non-surfactant-based anti-fogging agent from the viewpoints of anti-fogging property and transparency when a water film is formed. Here, the non-surfactant-based means that the content of the surfactant known as a component of the anti-fogging agent is 1% by mass or less based on the total amount of the non-volatile components of the anti-fogging agent. The anti-fogging agent may particularly not contain a surfactant such as an anionic surfactant, a cationic surfactant, a nonionic surfactant, or an amphoteric surfactant, or the content thereof may be 1% by mass or less based on the total amount of the non-volatile components of the anti-fogging agent.

[0068] The anti-fogging agent may contain colloidal silica, at least one selected from the group consisting of a cross-linking agent, a binder, and a metal chelate (colloidal silica binding material), and a liquid medium.

[0069] (Colloidal silica) As the colloidal silica, those having an average particle diameter (secondary particle diameter) of 1 to 1000 nm can be used. Since the particles are less likely to aggregate in the anti-fogging agent when the average particle diameter is 1 nm or more, the particles are likely to adhere to the substrate. On the other hand, when the average particle diameter is 1000 nm or less, the specific surface area of the particles increases, and the particles are likely to adhere to the substrate. From this viewpoint, the average particle diameter of the colloidal silica may be 3 to 700 nm, or may be 5 to 500 nm.

[0070] The average particle diameter can be measured, for example, by the following procedure. First, weigh about 100 μL (L represents liter; the same applies hereinafter) of the colloidal silica dispersion, and dilute it with ion-exchanged water so that the content of the colloidal silica is around 0.05 mass% (the content at which the transmittance (H) during measurement is 60 to 70%) to obtain a diluted solution. Then, put the diluted solution into the sample cell of a laser diffraction particle size distribution analyzer (manufactured by Horiba, Ltd., trade name: LA-920, refractive index: 1.93, light source: He-Ne laser, absorption 0) to measure the average particle diameter.

[0071] The number of silanol groups per gram of colloidal silica is 10×10 18 ~1000×10 18 per g, may be 50×10 18 ~800×10 18 per g, or may be 100×10 18 ~700×10 18 per g. When the number of silanol groups per gram of colloidal silica is 10×10 18 or more per g, the number of chemical bonding points with the functional groups of the substrate increases, so the adhesion to the substrate is likely to be improved. On the other hand, when the number of silanol groups is 1000×10 18 or less per g, the rapid polycondensation reaction between colloidal silicas during the preparation of the anti-fogging solution can be suppressed, and the reduction of the chemical bonding points with the functional groups of the substrate can be suppressed.

[0072] In this embodiment, the number of silanol groups (ρ [per g]) can be measured and calculated by the following titration.

[0073] [1] First, weigh 15 g of colloidal silica into a container (X [g]) whose mass has been measured, and disperse it in an appropriate amount (100 ml or less) of water. In the case of a dispersion in which colloidal silica is dispersed in a medium such as water, weigh the dispersion into the container so that the amount of colloidal silica is 15 g.

[0074] [2] Next, adjust the pH to 3.0 - 3.5 with 0.1 mol / L hydrochloric acid, measure the mass (Y [g]) at this time, and obtain the total mass of the liquid (Y - X [g]).

[0075] [3] Weigh an amount of liquid corresponding to 1 / 10 of the mass obtained in [2] ((Y - X) / 10 [g]) into another container. The amount of colloidal silica (A [g]) contained in the liquid at this stage is 1.5 g.

[0076] [4] Add 30 g of sodium chloride thereto, and further add ultrapure water to make the total amount 150 g. Adjust the pH to 4.0 with 0.1 mol / L sodium hydroxide solution to obtain a titration sample.

[0077] [5] Add 0.1 mol / L sodium hydroxide dropwise to this titration sample until the pH reaches 9.0, and obtain the amount of sodium hydroxide (B [mol]) required for the pH to change from 4.0 to 9.0.

[0078] [6] Calculate the silanol group number of colloidal silica from the following formula (1). ρ = B·N A / A·S BET ···(1) (In formula (1), N A [mol⁻¹] represents Avogadro's number. S BET [m² 2 / g] represents the BET specific surface area of colloidal silica.)

[0079] The above-mentioned BET specific surface area S BETIt is determined according to the BET specific surface area method. As a specific measurement method, for example, colloidal silica is placed in a dryer and dried at 150°C, then put into a measurement cell and vacuum degassed at 120°C for 60 minutes. For the sample, it can be determined by the one-point method or multi-point method of adsorbing nitrogen gas using a BET specific surface area measuring device. More specifically, first, the colloidal silica dried at 150°C is finely crushed with a mortar (magnetic, 100 ml) and put into a measurement cell as a measurement sample. Using a BET specific surface area measuring device (product name NOVE-1200) manufactured by Yuasa Ionics Co., Ltd., the BET specific surface area S BET is measured.

[0080] The degree of aggregation of colloidal silica may be, for example, 5.0 or less, 4.0 or less, 3.0 or less, 2.5 or less, or 2.0 or less. The degree of aggregation may be 1.0 or more, 1.3 or more, or 1.5 or more.

[0081] Here, in this specification, the degree of aggregation of colloidal silica in the colloidal silica dispersion refers to the ratio of the average particle diameter of the secondary particles of colloidal silica in the dispersion to the biaxial average primary particle diameter of colloidal silica (average particle diameter of secondary particles / biaxial average primary particle diameter). The average primary particle diameter can be measured, for example, by a known transmission electron microscope (for example, product name: H-7100FA manufactured by Hitachi High-Tech Corporation). For example, an image of the particles is taken using an electron microscope, the biaxial average primary particle diameter is calculated for a predetermined number of arbitrary particles, and the average value of these is obtained. In the case of colloidal silica, since the particle sizes are generally uniform, the number of particles to be measured may be, for example, about 20 particles. The average particle diameter of the secondary particles refers to the value obtained by the method described above.

[0082] The shape of colloidal silica is not particularly limited, and examples include pearl necklace shape, chain shape, spherical shape, cocoon shape, aggregated shape, and confectionery sugar shape. Among these, from the viewpoint of water retention, the pearl necklace shape and chain shape are preferred, and from the viewpoints of moisture resistance and water resistance, the pearl necklace shape is more preferred.

[0083] The colloidal silica may have its surface subjected to a coupling treatment with a modifier. The modifier is not particularly limited, and examples thereof include a silane coupling agent having a cationic group represented by the following general formula (2), a silane coupling agent having a sulfonic acid group which is an anionic group, or a compound having a functional group that can be converted into a silane coupling agent for the purpose of hydrophobization treatment, etc.

[0084]

Chemical formula

[0085] Specific examples of R include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, a pentyl group, an isopentyl group, a neopentyl group, a hexyl group, an isohexyl group, etc. An alkyl group having 1 to 3 carbon atoms is preferred, and a methyl group and an ethyl group are more preferred.

[0086] Specific examples of R' include a methyl group, an ethyl group, a propyl group, an isopropyl group, etc. A methyl group and an ethyl group are preferred.

[0087] Among R'', specific examples of the hydrocarbon having 1 to 4 carbon atoms include a methylene group, an ethylene group, a propylene group, an isopropylene group, a butylene group, an isobutylene group, etc. An alkylene group having 2 to 4 carbon atoms is preferred, and an ethylene group, a propylene group, and a butylene group are preferred.

[0088] Among “R”, specific examples of the hydrocarbon group having 1 to 4 carbon atoms substituted with an amino group include an aminomethylene group, an aminoethylene group, an aminopropylene group, an aminoisopropylene group, an aminobutylene group, an aminoisobutylene group, etc., and an aminoethylene group and an aminopropylene group are preferred.

[0089] Examples of the compound represented by the general formula (2) include aminopropyltrimethoxysilane, (aminoethyl)aminopropyltrimethoxysilane, aminopropyltriethoxysilane, aminopropyldimethylethoxysilane, aminopropylmethyldiethoxysilane, aminobutyltriethoxysilane, etc. These may be used alone or in combination.

[0090] Examples of the silane coupling agent having a functional group that can be chemically converted into a sulfonic acid group include: 1) a silane coupling agent having a sulfonic acid ester group that can be converted into a sulfonic acid group by hydrolysis; and 2) a silane coupling agent having a mercapto group and / or a sulfide group that can be converted into a sulfonic acid group by oxidation. Since the sulfonic acid modification of the colloidal silica surface is carried out in a solution, in order to improve the modification efficiency, it is preferable to use the latter silane coupling agent having a mercapto group and / or a sulfide group.

[0091] Examples of the silane coupling agent having a mercapto group include 3-mercaptopropyltrimethoxysilane, 2-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, etc.

[0092] Examples of the silane coupling agent having a sulfide group include bis(3-triethoxysilylpropyl)disulfide.

[0093] The silane coupling agent having a mercapto group and the silane coupling agent having a sulfide group may be used alone or in combination.

[0094] Examples of the silane coupling agent for the purpose of hydrophobization treatment include silylating agents and the like. A silylation reaction is carried out by containing a disiloxane compound and / or a monoalkoxysilane compound. Examples of the disiloxane compound as the silylating agent include compounds represented by the following general formula (I).

[0095]

Chemical formula

[0096] Examples of the disiloxane compound include hexamethyldisiloxane, 1,3-dibutyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, 1,3-divinyltetramethyldisiloxane, hexaethyldisiloxane, 3-glycidoxypropylpentamethyldisiloxane, etc., and hexamethyldisiloxane is preferred.

[0097] Examples of the monoalkoxysilane compound as the silylating agent include compounds represented by the following general formula (II).

[0098]

Chemical formula

[0099] Examples of the monoalkoxysilane compound include trimethylmethoxysilane, trimethylethoxysilane, trimethylpropoxysilane, phenyldimethylmethoxysilane, chloropropyldimethylmethoxysilane, etc., and trimethylmethoxysilane, trimethylethoxysilane, and trimethylpropoxysilane are preferred.

[0100] The silylating agent may be used alone or in combination of two or more kinds.

[0101] The colloidal silica may contain metal oxides other than silicon dioxide. The type of the metal oxide is not particularly limited, and for example, alumina can be mentioned. Examples of such colloidal silica include colloidal silica in which a sufficient amount of aluminosilicate is firmly formed on the surface of the colloidal silica for the stabilization of the silica sol.

[0102] The content of the colloidal silica can be 1 to 20% by mass based on the total amount of the anti-fogging agent. When the content is 1% by mass or more, sufficient anti-fogging properties are likely to be exhibited. On the other hand, when it is 20% by mass or less, the polycondensation reaction of the silanol groups between the particles is suppressed, and the anti-fogging property (hydrophilicity) is likely to be maintained. From this viewpoint, the content of the colloidal silica can be 1.5 to 15% by mass, can be 2 to 13% by mass, and can be 3 to 10% by mass.

[0103] The colloidal silica is available as a colloidal silica dispersion. Examples of the dispersion medium include water, isopropyl alcohol, 1-methoxy-2-propyl alcohol, ethyl alcohol, methyl alcohol, ethylene glycol, ethylene glycol-n-propyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, dimethylacetamide, N-methylpyrrolidone, toluene, methyl ethyl ketone, methyl isobutyl ketone, cyclohexane, ethyl acetate, etc. The dispersion medium may be water, alcohols, or a mixture of water and alcohols. Among these, water is preferred from the viewpoint of versatility.

[0104] The pH of the colloidal silica dispersion may be from 2 to 10. When the pH is from 6 to 8, if there are alkoxy groups on the surface of the colloidal silica, the hydrolysis reaction rate thereof becomes slow. Thereby, it is easy to form a coating film of colloidal silica with alkoxy groups remaining. In this case, since the polycondensation reaction of silanol groups due to moisture absorption can be suppressed, it is easy to maintain the anti-fog property (hydrophilicity) of the film surface. When the pH is from 2 to 5 or from 8 to 10, if there are alkoxy groups on the surface of the colloidal silica, the hydrolysis reaction rate thereof becomes fast. Thereby, more silanol groups can be generated, and the adhesion to the substrate is liable to be improved.

[0105] The pH of the colloidal silica dispersion can be measured with a pH meter (for example, manufactured by Electrochemical Instruments Co., Ltd., model number: PHL-40). As the measured value of the pH, after three-point calibration using standard buffer solutions (phthalate pH buffer solution pH: 4.01 (25 °C), neutral phosphate pH buffer solution pH: 6.86 (25 °C), borate pH buffer solution pH: 9.18 (25 °C)), the electrode is placed in the dispersion, and the value after at least 2 minutes has elapsed and it has become stable is adopted.

[0106] The zeta potential of the colloidal silica in the dispersion is preferably from -50 mV to 40 mV. When the zeta potential is from -10 mV to 10 mV, the repulsion between particles becomes small when coating, and it adheres closely to the substrate, so the hydrophilicity of the substrate is liable to be improved. When the zeta potential is from -50 mV to -11 mV, or from 11 mV to 40 mV, the particles are liable to repel each other in the dispersion, and the dispersibility becomes high, so it is easy to suppress the aggregation of the particles.

[0107] The zeta potential of colloidal silica can be measured with a zeta potential measuring instrument (for example, manufactured by Beckman Coulter, model number: Coulter Delsa 440). As a method for measuring the zeta potential, first, pure water is added to the colloidal silica dispersion so that the silica particle concentration becomes 5 ppm based on the total amount of the test solution, and a test solution in which silica particles are dispersed by ultrasonic treatment is prepared. Next, the test solution is put into a measurement cell with platinum electrodes attached to both sides, and when a voltage of 10 V is applied to both electrodes, the silica particles with charges move to the electrode side with the pole opposite to their charges. Then, the moving speed of the silica particles with charges is determined.

[0108] As the raw material of colloidal silica, water glass or alkoxysilane may be used, and it is not particularly limited.

[0109] The production process in the case where the raw material is water glass is not particularly limited. For example, sodium silicate is heated and concentrated by a hydrothermal synthesis method to produce particles. For example, an aggregate with a three-dimensional network structure may be produced in a state where the growth of primary particles is suppressed at an acidic pH and then crushed, or a block-shaped aggregate may be produced by accelerating the growth of primary particles at an alkaline pH and then crushed.

[0110] The production process in the case where the raw material is alkoxysilane is not particularly limited. For example, alkoxysilane is subjected to sol-gel synthesis to produce particles. For example, after promoting the hydrolysis reaction of alkoxysilane and then promoting the polycondensation reaction to obtain a gel, the internal solvent may be removed by heat treatment. Alternatively, after obtaining the gel, solvent substitution may be performed with a predetermined solvent.

[0111] Commercially available products may be used as the colloidal silica dispersion. For example, ST-PS-SO (manufactured by Nissan Chemical Industries, Ltd.), ST-PS-MO (manufactured by Nissan Chemical Industries, Ltd.), ST-PS-M (manufactured by Nissan Chemical Industries, Ltd.), ST-PS-S (manufactured by Nissan Chemical Industries, Ltd.), ST-UP (manufactured by Nissan Chemical Industries, Ltd.), ST-OUP (manufactured by Nissan Chemical Industries, Ltd.), IPA-ST-UP (manufactured by Nissan Chemical Industries, Ltd.), MA-ST-UP (manufactured by Nissan Chemical Industries, Ltd.), PGM-ST-UP (manufactured by Nissan Chemical Industries, Ltd.), MEK-ST-UP (manufactured by Nissan Chemical Industries, Ltd.), IPA-ST (manufactured by Nissan Chemical Industries, Ltd.), IPA-ST-L (manufactured by Nissan Chemical Industries, Ltd.), IPA-ST-ZL (manufactured by Nissan Chemical Industries, Ltd.), MA-ST-M (manufactured by Nissan Chemical Industries, Ltd.), MA-ST-L (manufactured by Nissan Chemical Industries, Ltd.), MA-ST-ZL (manufactured by Nissan Chemical Industries, Ltd.), EG-ST (manufactured by Nissan Chemical Industries, Ltd.), EG-ST-XL-30 (manufactured by Nissan Chemical Industries, Ltd.), NPC-ST-30 (manufactured by Nissan Chemical Industries, Ltd.), PGM-ST (manufactured by Nissan Chemical Industries, Ltd.), DMAC-ST (manufactured by Nissan Chemical Industries, Ltd.), DMAC-ST-ZL (manufactured by Nissan Chemical Industries, Ltd.), NMP-ST (manufactured by Nissan Chemical Industries, Ltd.), TOL-ST (manufactured by Nissan Chemical Industries, Ltd.), MEK-ST-40 (manufactured by Nissan Chemical Industries, Ltd.), MEK-ST-L (manufactured by Nissan Chemical Industries, Ltd.), MEK-ST-ZL (manufactured by Nissan Chemical Industries, Ltd.), MIBK-ST (manufactured by Nissan Chemical Industries, Ltd.), MIBK-ST-L (manufactured by Nissan Chemical Industries, Ltd.), CHO-ST-M (manufactured by Nissan Chemical Industries, Ltd.), EAC-ST (manufactured by Nissan Chemical Industries, Ltd.), PMA-ST (manufactured by Nissan Chemical Industries, Ltd.), MEK-EC-2130Y (manufactured by Nissan Chemical Industries, Ltd.), MEK-EC-2430Z (manufactured by Nissan Chemical Industries, Ltd.), MEK-EC-2140Z (manufactured by Nissan Chemical Industries, Ltd.), MEK-AC-4130Z (manufactured by Nissan Chemical Industries, Ltd.), MEK-AC-5140Z (manufactured by Nissan Chemical Industries, Ltd.), PGM-AC-2140Y (manufactured by Nissan Chemical Industries, Ltd.), PGM-AC-4130Y (manufactured by Nissan Chemical Industries, Ltd.), MIBK-AC-2140Z (manufactured by Nissan Chemical Industries, Ltd.), MIBK-SD-L (manufactured by Nissan Chemical Industries, Ltd.), ST-XS (manufactured by Nissan Chemical Industries, Ltd.), ST-OXS (manufactured by Nissan Chemical Industries, Ltd.), ST-NXS (manufactured by Nissan Chemical Industries, Ltd.), ST-CXS (manufactured by Nissan Chemical Industries, Ltd.), ST-S (manufactured by Nissan Chemical Industries, Ltd.), ST-OS (manufactured by Nissan Chemical Industries, Ltd.), ST-NS (manufactured by Nissan Chemical Industries, Ltd.).ST-30 (manufactured by Nissan Chemical Industries, Ltd.), ST-O (manufactured by Nissan Chemical Industries, Ltd.), ST-N (manufactured by Nissan Chemical Industries, Ltd.), ST-C (manufactured by Nissan Chemical Industries, Ltd.), ST-AK (manufactured by Nissan Chemical Industries, Ltd.), ST-50-T (manufactured by Nissan Chemical Industries, Ltd.), ST-O-40 (manufactured by Nissan Chemical Industries, Ltd.), ST-N-40 (manufactured by Nissan Chemical Industries, Ltd.), ST-CM (manufactured by Nissan Chemical Industries, Ltd.), ST-30L (manufactured by Nissan Chemical Industries, Ltd.), ST-OL (manufactured by Nissan Chemical Industries, Ltd.), ST-AK-L (manufactured by Nissan Chemical Industries, Ltd.), ST-YL (manufactured by Nissan Chemical Industries, Ltd.), ST-OYL (manufactured by Nissan Chemical Industries, Ltd.), ST-AK-YL (manufactured by Nissan Chemical Industries, Ltd.), ST-ZL (manufactured by Nissan Chemical Industries, Ltd.), MP-1040 (manufactured by Nissan Chemical Industries, Ltd.), MP-2040 (manufactured by Nissan Chemical Industries, Ltd.), MP-4540M (manufactured by Nissan Chemical Industries, Ltd.), PL-1-IPA (manufactured by Fuso Chemical Co., Ltd.), PL-1-TOL (manufactured by Fuso Chemical Co., Ltd.), PL-2L-PGME (manufactured by Fuso Chemical Co., Ltd.), PL-2L-MEK (manufactured by Fuso Chemical Co., Ltd.), PL-2L (manufactured by Fuso Chemical Co., Ltd.), PL-3 (manufactured by Fuso Chemical Co., Ltd.), PL-4 (manufactured by Fuso Chemical Co., Ltd.), PL-5 (manufactured by Fuso Chemical Co., Ltd.), PL-1H (manufactured by Fuso Chemical Co., Ltd.), PL-3H (manufactured by Fuso Chemical Co., Ltd.), PL-5H (manufactured by Fuso Chemical Co., Ltd.), BS-2L (manufactured by Fuso Chemical Co., Ltd.), BS-3L (manufactured by Fuso Chemical Co., Ltd.), BS-5L (manufactured by Fuso Chemical Co., Ltd.), HL-2L (manufactured by Fuso Chemical Co., Ltd.), HL-3L (manufactured by Fuso Chemical Co., Ltd.), HL-4L (manufactured by Fuso Chemical Co., Ltd.), PL-3-C (manufactured by Fuso Chemical Co., Ltd.), PL-3-D (manufactured by Fuso Chemical Co., Ltd.), TCSOL800 (manufactured by Tama Chemical Industry Co., Ltd.), SI-40 (manufactured by JGC Catalysts & Chemicals Ltd.), SI-50 (manufactured by JGC Catalysts & Chemicals Ltd.), SI-45P (manufactured by JGC Catalysts & Chemicals Ltd.), SI-80P (manufactured by JGC Catalysts & Chemicals Ltd.), SIK-23 (manufactured by JGC Catalysts & Chemicals Ltd.), S-30H (manufactured by JGC Catalysts & Chemicals Ltd.), SIK-15 (manufactured by JGC Catalysts & Chemicals Ltd.), SI-550 (manufactured by JGC Catalysts & Chemicals Ltd.), etc.

[0112] (Liquid medium) The liquid medium is a medium responsible for the dispersion of colloidal silica, the dissolution of the colloidal silica binding material, etc. in the anti-fogging agent. The liquid medium is a medium having a boiling point lower than 185°C. The liquid medium volatilizes upon heating during the formation of the anti-fogging film, whereby the colloidal silicas approach each other and it becomes easier for bonds to be formed. As the liquid medium, the same one as the dispersion medium contained in the colloidal silica dispersion or a different one may be used.

[0113] As the liquid medium, for example, water, an organic solvent, or a mixed solvent thereof can be used. Examples of the organic solvent include alcohols such as methyl alcohol, ethyl alcohol, 1-propanol, isopropyl alcohol, 1-butyl alcohol, 2-butyl alcohol, isobutyl alcohol, diacetone alcohol, 1-butoxy-2-propanol, 1-hexanol, 1-octanol, 2-octanol, 3-methoxy-3-methyl-1-butanol, etc., glycols such as polyethylene glycol, glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol mono-tert-butyl ether, propylene glycol monomethyl ether acetate, propylene glycol n-propyl ether, propylene glycol monomethyl ether, etc., ketones such as acetone, methyl ethyl ketone, etc., ethers such as tetrahydrofuran, dioxane, etc., esters such as ethyl acetate, butyl acetate, etc., cyclic hydrocarbons such as cyclohexane, and acetonitrile. These may be used alone or in combination of two or more, but those that can be uniformly dispersed in the colloidal silica dispersion are desirable. For example, when the dispersion medium of the colloidal silica dispersion is water, ethylene glycol monobutyl ether etc. are preferable.

[0114] (Metal chelate) The metal chelate functions as a colloidal silica binding material and can form an anti-fogging film excellent in moisture resistance and water resistance.

[0115] The metal chelate is not particularly limited and can be appropriately selected from known metal chelates. Examples of the metal chelate include zirconium chelate compounds, titanium chelate compounds, nickel chelate compounds, aluminum chelate compounds, tin chelate compounds, and the like.

[0116] Examples of the zirconium chelate compound include zirconium tetrakis(acetylacetonate), zirconium bis(butoxy)bis(acetylacetonate), and the like.

[0117] Examples of the titanium chelate compound include titanium tetrakis(acetylacetonate), titanium bis(butoxy)bis(acetylacetonate), and the like.

[0118] Examples of the nickel chelate compound include CR12 (manufactured by Momentive Performance Materials Japan), Ni(AcAc) 2 and the like.

[0119] Examples of the aluminum chelate compound include aluminum bis(ethylacetoacetate)mono(acetylacetonate), aluminum tris(acetylacetonate), aluminum ethylacetoacetate diisopropylate, and the like.

[0120] Examples of the tin chelate compound include dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dioctoate, and the like.

[0121] Among the above, from the viewpoints of moisture resistance and water resistance, the metal chelate is more preferably a zirconium chelate compound, a titanium chelate compound, or a nickel chelate compound.

[0122] The metal chelate may be a commercially available product. For example, the zirconium chelate compound may be ZC-150 (manufactured by Matsumoto Fine Chemical Co., Ltd.), the aluminum chelate compound may be Aluminum Chelate D (manufactured by Kawaken Fine Chemicals Co., Ltd.), Plane Act AL-M (manufactured by Ajinomoto Fine-Techno Co., Inc.), and the nickel chelate compound may be acetylacetone nickel (II) hydrate (manufactured by Tokyo Chemical Industry Co., Ltd.) and is available.

[0123] The anti-fogging agent may contain one kind of metal chelate or may contain two or more kinds of metal chelates.

[0124] From the viewpoints of moisture resistance, water resistance, stain resistance, water dripping property, etc. of the anti-fogging film, the content of the metal chelate may be 0.01 to 5.0 parts by mass, 0.05 to 2.0 parts by mass, or 0.1 to 1.0 parts by mass with respect to 100 parts by mass of colloidal silica.

[0125] When using a metal chelate, for example, an anti-fogging agent can be obtained by adding a liquid medium, a metal chelate, and an acid catalyst (nitric acid) to the aqueous dispersion silica sol in this order.

[0126] (Binder) The binder functions as a colloidal silica binding material and can form an anti-fogging film excellent in moisture resistance and water resistance. The binder is a medium having a boiling point of 185°C or higher.

[0127] Examples of binders include saccharides such as cellulose, carboxymethyl cellulose, dextrin, chitin, chitosan, xanthan gum, glycol ethers such as ethylene glycol monobutyl ether, ethylene glycol monopropyl ether, ethylene glycol mono-tert-butyl ether, triethylene glycol butyl methyl ether, propylene glycol n-butyl ether, dipropylene glycol methyl ether, dipropylene glycol n-butyl ether, alcohols such as polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl acetal, glycols such as polyoxyethylene polyoxypropylene glycol, ethylene glycol, diethylene glycol, propylene glycol, polyethylene glycol, ethers such as lauryl alcohol glycidyl ether, glycerol polyglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerin, polyacrylic acid, acrylic resin, epoxy resin, urethane resin, polyvinyl pyrrolidone, polyvinyl pyrrolidone vinyl acetate copolymer (vinyl acetate pyrrolidone copolymer), N-methyl pyrrolidone, dimethyl sulfoxide, polysaccharides such as cellulose nanofiber, and silane oligomer.

[0128] The above binder components may be used alone or in combination of two or more according to the purpose, application, etc. However, from the viewpoint of excellent water resistance and moisture resistance, the binder components may be cellulose, polyethylene glycol, glycerol polyglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerin, acrylic resin, polyacrylic acid, polyvinyl alcohol, or polyvinyl pyrrolidone.

[0129] The anti-fogging agent may contain one type of binder or two or more types of binders.

[0130] The content of the binder may be 0.001 to 5.0 parts by mass, 0.005 to 2.0 parts by mass, or 0.01 to 1.0 parts by mass with respect to 100 parts by mass of colloidal silica, from the viewpoints of moisture resistance, water resistance, stain resistance, water dripping property, etc. of the anti-fog film.

[0131] When using a binder component, for example, an anti-fog agent can be obtained by adding a liquid medium, a binder component (added as a dispersion of the binder component), and an acid catalyst (nitric acid) to a water-dispersed silica sol in this order.

[0132] (Cross-linking agent) The cross-linking agent functions as a colloidal silica binding material and can form an anti-fog film excellent in moisture resistance and water resistance. Examples of the cross-linking agent include silane coupling agents.

[0133] Examples of the silane coupling agent include silane compounds having a vinyl group, an epoxy group, a styryl group, an acryloyl group, a methacryloyl group, an amino group, a ureido group, an isocyanate group, an isocyanurate group, a mercapto group, a fluoro group, an alkyl group, etc., or a silane oligomer having a silanol group.

[0134] Examples of the silane coupling agent having a vinyl group include KBM-1003, KBE-1003 (both are trade names, manufactured by Shin-Etsu Chemical Co., Ltd. The same applies hereinafter).

[0135] Examples of the silane coupling agent having an epoxy group include KBM-303, 402, 403, 4803, KBE-402, 403, X-12-981S, X-12-984S, etc.

[0136] Examples of the silane coupling agent having a styryl group include KBM-1403.

[0137] Examples of the silane coupling agent having a methacryloyl group include KBM-502, 503, KBE-502, 503, etc.

[0138] Examples of silane coupling agents having an acryloyl group include KBM-5103, X-12-1048, X-12-1050, etc.

[0139] Examples of silane coupling agents having an amino group include KBM-602, 603, 903, 573, 575, 6803, KBE-903, 9103P, X-12-972F, etc.

[0140] Examples of silane coupling agents having a ureido group include KBE-585A, etc.

[0141] Examples of silane coupling agents having an isocyanate group include KBE-9007, X-12-1159L, etc.

[0142] Examples of silane coupling agents having an isocyanurate group include KBM-9659, etc.

[0143] Examples of silane coupling agents having a mercapto group include KBM-802, 803, X-12-1154, X-12-1156, etc.

[0144] Examples of silane coupling agents having a fluoro group include KBM-7103, etc.

[0145] Examples of other silane coupling agents include KBE-04, KBM-13, KBM-22, KBM-103, KBM-202SS, KBM-3033, KBM-3063, KBM-3103C, KBM-3066, KBM-7103, KBE-22, KBE-103, KBE-3033, KBE-3063, KBE-3083, etc.

[0146] Examples of the silane oligomer having a silanol group include ethyl silicate 28, ethyl silicate 28P, ethyl silicate 40, ethyl silicate 48, EMS-485, methyl silicate 51, methyl silicate 53A, N-propyl silicate, N-butyl silicate, Corcoat PX, Corcoat N-103X, and the like.

[0147] The above silane coupling agent may be used alone or in combination of two or more depending on the purpose, application, etc. However, from the viewpoint of excellent anti-fogging property of the anti-fogging film, the silane coupling agent may be a silane coupling agent having an epoxy group, an amino group, or a ureido group.

[0148] The content of the silane coupling agent may be 1.0 to 100.0 parts by mass, 5.0 to 100.0 parts by mass, 6.0 to 50.0 parts by mass, or 7.0 to 20.0 parts by mass with respect to 100 parts by mass of colloidal silica from the viewpoints of moisture resistance, water resistance, stain resistance, water dripping property, etc. of the anti-fogging film.

[0149] When using a silane coupling agent, for example, an anti-fogging agent can be obtained by adding a liquid medium, a silane coupling agent, and an acid catalyst (nitric acid) to a water-dispersed silica sol in this order.

[0150] (Other components) The anti-fogging agent may contain various conventional additives such as an antioxidant, an ultraviolet absorber, and a light stabilizer if necessary. Further, the anti-fogging agent may contain nitric acid, acetic acid, hydrochloric acid, nitric acid, phosphoric acid, p-toluenesulfonic acid sulfate, benzenesulfonic acid, methanesulfonic acid, phenolsulfonic acid, oxalic acid, maleic acid, malonic acid, tartaric acid, citric acid, malic acid, acetic acid, lactic acid, succinic acid, benzoic acid, ammonia, urea, imidazole, sodium carbonate, calcium carbonate, etc. as an antifoaming agent, a catalyst, etc. used when preparing the raw materials. Further, a thickening agent may be used from the viewpoint of the viscosity of the solution.

[0151] <Hydrophilic agent> Since the anti-fogging agent can hydrophilize the target surface, it can be referred to as a hydrophilizing agent. For the specific embodiments of the hydrophilizing agent, reference can be made to the above description regarding the anti-fogging agent. The hydrophilizing agent may have the same water film uniformity index WE and anti-fogging index AFI as the anti-fogging agent according to the above-described present embodiment, and may have the same composition as the anti-fogging agent according to the above-described present embodiment.

[0152] By using the hydrophilizing agent, a hydrophilization treatment can be performed on the substrate.

[0153] Examples of the material constituting the substrate include, in addition to the above polycarbonate, resin materials such as acrylic polymer, polyamide, polyacrylate, polyimide, acrylonitrile-styrene copolymer, styrene-acrylonitrile-butadiene copolymer, polyvinyl chloride, polyethylene, polycarbonate, etc., metal materials such as aluminum, magnesium, copper, zinc, iron, titanium, chromium, manganese, cobalt, nickel, etc., ceramic materials such as silicon oxide, aluminum oxide, magnesium oxide, copper oxide, zinc oxide, iron oxide, titanium oxide, chromium oxide, manganese oxide, cobalt oxide, nickel oxide, etc., and glass. Examples of articles provided with such a substrate include, in addition to the above vehicle lamp structure (automobile headlight, etc.), the front glass of a vehicle, glasses, goggles, mirrors, storage containers, windows, camera lenses, etc.

[0154] <Anti-fogging Method for Vehicle Lamp Structure> The anti-fogging method for a vehicle lamp structure is to treat the inner surface of the lens provided in the vehicle lamp structure with the anti-fogging agent of the above-described present embodiment. The treatment with the anti-fogging agent may include, for example, a step of applying the anti-fogging agent to the inner surface of the lens to form a coating film (coating step) and a step of drying the coating film (drying step). Prior to the coating step, a cleaning step may be performed for the purpose of removing a mold release agent that may adhere to the surface of the lens.

[0155] (Cleaning Step) The cleaning liquid used in the cleaning process is not particularly limited. However, in view of the fact that the inner surface substrate of the lens provided in the most common vehicle lamp structure is polycarbonate, a liquid that does not dissolve the polycarbonate substrate is preferred, and water, alcohols, etc. are more preferred. Specifically, water, isopropyl alcohol, methanol, ethanol, etc. are preferred. The cleaning process may be performed by wiping the substrate using a cloth or the like impregnated with the cleaning liquid.

[0156] (Coating process) The coating process is, for example, a process of coating the anti-fogging agent on the inner surface of the lens. The anti-fogging agent may be coated on the entire inner surface of the lens or selectively coated on a part thereof.

[0157] The coating method is not particularly limited. Examples thereof include a spin coating method, a dip coating method, a spray coating method, a flow coating method, a bar coating method, and a gravure coating method. In particular, the spray coating method is preferable from the viewpoints of easily forming an anti-fogging film with a uniform thickness even on a processed surface with unevenness, high productivity, and high usage efficiency of the anti-fogging agent. These methods may be used alone or in combination of two or more. Note that the anti-fogging agent may be impregnated into a cloth or the like and then applied.

[0158] The coating amount is not limited because it depends on the components of the anti-fogging agent, its content, etc. For example, it can be 10 -9 ~10 3 g / m 2 2.

[0159] The temperature of the anti-fogging agent used in the coating process may be, for example, 1 to 50°C or 10 to 30°C. By setting the above temperature to 1°C or higher, the anti-fogging property and adhesion tend to be further improved. By setting the above temperature to 50°C or lower, the transparency of the anti-fogging film tends to be easily obtained. The treatment time with the anti-fogging agent can be, for example, 1 second to 1 hour or 5 to 30 minutes.

[0160] (Drying process) In this process, after applying the anti-fogging agent, the liquid medium is volatilized from the anti-fogging agent. The liquid medium can be volatilized, for example, by leaving it at room temperature. However, by carrying out this process at a higher temperature, the adhesion between the inner surface of the lens and the anti-fogging film can be further improved. The drying temperature at this time is not particularly limited and varies depending on the heat-resistant temperature of the lens. For example, it may be 5 to 300 °C, or it may be 10 to 200 °C. By setting the above temperature to 5 °C or higher, better adhesion can be achieved, and by setting it to 300 °C or lower, deterioration due to heat can be more suppressed. The drying time can be 30 seconds to 150 hours. By this process, an anti-fogging film containing colloidal silica is formed on the inner surface of the lens.

[0161] The thickness of the anti-fogging film is not particularly limited, but from the viewpoints of transparency, anti-fogging property, etc., it can be about 1 nm to 5 mm, 5 nm to 10 μm, or 10 nm to 5 μm. The film thickness of the anti-fogging film can be measured, for example, by a non-contact film thickness gauge Optical NanoGauge C13027 (manufactured by Hamamatsu Photonics K.K.).

[0162] The water contact angle of the anti-fogging film can be 40° or less, and may be 20° or less, with respect to a 1 μL droplet of ultrapure water. Thereby, the anti-fogging property can be sufficiently exhibited. The contact angle can be calculated, for example, based on the average value of 10 measurements using a contact angle meter.

[0163] The anti-fogging film can have a visible light transmittance of 85% or more, 90% or more, or 95% or more. Thereby, the brightness of the vehicle lamp can be sufficiently maintained at a high level. The visible light transmittance of the anti-fogging film can be measured, for example, by a U-3500 type recording spectrophotometer (manufactured by Hitachi, Ltd.).

[0164] The anti-fogging film can have a haze of 6.0 or less, 3.0 or less, or 1.0 or less. Thereby, the brightness of the vehicle lamp can be sufficiently maintained at a high level. The haze of the anti-fogging film can be measured, for example, by a haze meter (NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd.).

[0165] The anti-fog film can have a YI of 4.0 or less, 3.0 or less, or 1.5 or less. Thereby, the brightness of the vehicle lamp can be maintained sufficiently high. The YI of the anti-fog film can be measured, for example, by a colorimeter (300A, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0166] Fig. 6 is a diagram schematically showing a vehicle lamp structure. The inner surface of the lens of the vehicle lamp structure is subjected to an anti-fog treatment by the anti-fog method of the vehicle lamp structure using the above anti-fog agent. The lamp structure 100 shown in Fig. 6 includes a lamp housing 103 configured in a concave shape with one side open, and a lens 101 that closes the open side of the lamp housing 103. The material of the lens 101 is, for example, polycarbonate. A lamp chamber S is formed by the lamp housing 103 and the lens 101. A light source 104 disposed in the lamp chamber S is attached to the lamp housing 103. As the light source 104, an incandescent bulb, an LED bulb, a halogen bulb, etc. are appropriately adopted. In the lamp chamber S, as shown in the figure, a reflector 105 that functions as a reflector for the light of the light source 104 may be provided so as to surround the light source 104 from the rear side. An anti-fog film 102 formed by the above anti-fog agent is provided on the inner surface of the lens 101, that is, the surface facing the lamp chamber S. The anti-fog film 102 may be provided on the entire inner surface of the lens 101, or may be selectively provided in part as shown in Fig. 6.

[0167] Since the vehicle lamp structure is subjected to an anti-fog treatment with the anti-fog agent of the present embodiment having a water film uniformity index WE of 65% or more, it has excellent anti-fog properties and can sufficiently maintain the straightness and intensity of the light transmitted when a water film is formed.

Examples

[0168] Hereinafter, the present invention will be described more specifically by way of examples and comparative examples, but the present invention is not limited to the following examples.

[0169] <Preparation of anti-fog agent> As an anti-fogging agent, the following coating liquids were prepared respectively.

[0170] (Example 1) 0.05 g of 60L (manufactured by Daito Kasei Kogyo Co., Ltd.), which is cellulose, was mixed with 99.95 g of a mixed solution of water and ethanol (the mass ratio of water to ethanol (water:ethanol) is 1:1) to obtain a 0.05 mass% aqueous dispersion cellulose solution. 4.00 g of ST-PS-SO (manufactured by Nissan Chemical Industries, Ltd., 15 wt% - water, pearl necklace-shaped silica), which is an aqueous dispersion silica sol, 6.86 g of water, 3.27 g of ethylene glycol monobutyl ether, 0.12 g of the 0.05 mass% aqueous dispersion cellulose solution, and 0.75 g of nitric acid diluted to 10 mass% were mixed and stirred for 1 hour to obtain a coating liquid.

[0171] (Example 2) 0.05 g of 60L, which is cellulose, was mixed with 99.95 g of a mixed solution of water and ethanol (the mass ratio of water to ethanol (water:ethanol) is 1:1) to obtain a 0.05 mass% aqueous dispersion cellulose solution. 4.00 g of ST-PS-SO, 6.68 g of water, 3.27 g of ethylene glycol monobutyl ether, 0.02 g of silane coupling agent KBE-585A having a ureido group, 0.12 g of the 0.05 mass% aqueous dispersion cellulose solution, and 0.75 g of nitric acid diluted to 10 mass% were mixed and stirred for 1 hour to obtain a coating liquid.

[0172] (Example 3) 0.12 g of 1WX-049 (manufactured by Daiso Fine Chemical Co., Ltd., solid content 40.7 mass%), which is polyacrylic acid, was mixed with 99.88 g of water to obtain a 0.05 mass% aqueous dispersion polyacrylic acid solution. 4.00 g of ST-PS-SO, 6.43 g of water, 3.27 g of ethylene glycol monobutyl ether, 0.1 g of KBE-585A, and 0.12 g of the 0.05 mass% aqueous dispersion polyacrylic acid solution were mixed and stirred for 1 hour to obtain a coating liquid.

[0173] (Example 4) Instead of 1WX-049, 0.10 g of E535 (manufactured by Ashland Japan Co., Ltd., solid content 50%), which is a vinylpyrrolidone acetate copolymer, and 99.9 g of water were mixed to obtain a 0.05 mass% vinylpyrrolidone acetate copolymer solution. A coating solution was obtained in the same manner as in Example 3, except for the above.

[0174] (Example 5) A coating solution was obtained in the same manner as in Example 3, except that glycerin was used instead of 1WX-049.

[0175] (Example 6) A coating solution was obtained in the same manner as in Example 3, except that dextrin was used instead of 1WX-049.

[0176] (Example 7) A coating solution was obtained in the same manner as in Example 3, except that PEG200, which is polyethylene glycol, was used instead of 1WX-049.

[0177] (Example 8) 0.05 g of 60L, which is cellulose, and 99.95 g of a mixed solution of water and ethanol (mass ratio of water to ethanol (water:ethanol) is 1:1) were mixed to obtain a 0.05 mass% aqueous dispersion of cellulose. 4.00 g of ST-PS-SO4, which is an aqueous silica sol, 6.75 g of water, 3.27 g of ethylene glycol monobutyl ether, 0.12 g of a 0.05 mass% aqueous dispersion of cellulose, 0.1 g of KBE-585A, 0.01 g of aluminum chelate D (Al-D: manufactured by Kawaken Fine Chemical Co., Ltd.), which is an aluminum chelate compound, and 0.75 g of nitric acid diluted to 10 mass% were mixed and stirred for 1 hour to obtain a coating solution.

[0178] (Example 9) Instead of aluminum chelate D, 0.0005 g of Zr(acac) 4 (manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and 6.78 g of water was added instead of 6.75 g of water. A coating solution was obtained in the same manner as in Example 8, except for the above.

[0179] (Example 10) 4.00 g of ST-PS-SO, which is an aqueous dispersion silica sol, 10.01 g of isopropyl alcohol, 0.24 g of KBE-585A, and 0.75 g of nitric acid diluted to 10% by mass were mixed and stirred for 1 hour to obtain a coating solution.

[0180] (Example 11) A coating solution was obtained in the same manner as in Example 10, except that 10.00 g of ST-PS-SO was used instead of 4.00 g of ST-PS-SO, and 0.20 g of KBE-04 (manufactured by Shin-Etsu Chemical Co., Ltd.), which is ethyl orthosilicate, was added instead of 0.24 g of KBE-585A.

[0181] (Example 12) 4.00 g of ST-PS-SO, which is an aqueous dispersion silica sol, 6.97 g of water, 3.27 g of ethylene glycol monobutyl ether, 0.01 g of CR12, which is a nickel chelate compound, and 0.75 g of nitric acid diluted to 10% by mass were mixed and stirred for 1 hour to obtain a coating solution.

[0182] The compositions of the coating solutions obtained above (however, the liquid medium and nitric acid are omitted) are shown in Table 1 and Table 2. Also, in the tables, the amount of silane coupling agent, the amount of binder, and the amount of metal chelate indicate the amounts (parts by mass) relative to 100 parts by mass of silica.

[0183] (Comparative Example 1) 4.00 g of IPA-ST-UP (manufactured by Nissan Chemical Industries, Ltd., 15 wt%-isopropyl alcohol), which is an isopropyl alcohol-dispersed silica sol, 6.98 g of water, 3.27 g of isopropyl alcohol, and 0.75 g of nitric acid diluted to 10% by mass were mixed and stirred for 1 hour to obtain a coating solution.

[0184] (Comparative Example 2) A coating solution was obtained in the same manner as in Comparative Example 1, except that 4.00 g of IPA-ST (manufactured by Nissan Chemical Industries, Ltd., 30 wt%-isopropyl alcohol), which is an isopropyl alcohol-dispersed silica sol, was added instead of IPA-ST-UP.

[0185] (Comparative Example 3) 1.5 g of 1WX-049 (a quaternary ammonium salt type hydrophilic polymer manufactured by Dainippon Fine Chemical Co., Ltd.) and 13.5 g of ethylene glycol monobutyl ether were mixed and stirred for 1 hour to obtain a coating solution.

[0186] (Comparative Example 4) 1.5 g of KBE-9103P, which is a silane coupling agent having an amino group, 12.8 g of isopropyl alcohol, and 0.75 g of nitric acid diluted to 10% by mass were mixed and stirred for 1 hour to obtain a coating solution.

[0187] (Comparative Example 5) A coating solution was obtained in the same manner as in Comparative Example 4, except that KBE-403, a silane coupling agent having an epoxy group, was used instead of KBE-9103P.

[0188] (Comparative Example 6) A coating solution was obtained in the same manner as in Comparative Example 4, except that KBM-5103, a silane coupling agent having an acryloyl group, was used instead of KBE-9103P.

[0189]

Table 1

[0190]

Table 2

[0191]

Table 3

[0192] [Anti-fogging treatment on polycarbonate substrate] A polycarbonate substrate with a size of 10 cm square and a thickness of 2 mm (visible light transmittance: 90%, haze: 0.1, YI: 0.2) was washed with isopropyl alcohol. Using an applicator, the coating solutions obtained in each preparation example and comparative preparation example were applied to the substrate so that the thickness after drying would be 1 μm, and then heated at 110 °C for 30 minutes to obtain a polycarbonate substrate with an anti-fogging film having a thickness of 1 μm as a sample. For the coating solutions of Comparative Preparation Examples 3 to 6, the thickness was adjusted by repeating the coating and drying processes.

[0193] <Evaluation> The following evaluations were performed on the samples obtained above.

[0194] (Anti-fogging index) Using the apparatus shown in Figure 2, an anti-fogging evaluation image and a reference image were obtained under the following imaging conditions. The anti-fogging index AFI was calculated by the calculation method shown below using the obtained evaluation image and reference image.

[0195] [Imaging conditions] Sample image: Checkerboard pattern of black and white squares, side length of square 0.5 mm Water temperature: 40 °C Distance D1: 1.5 cm Depth D2: 1 cm Distance D3: 17 cm (distance from the sample image to the central surface of the frontmost lens) Digital camera: Canon PowerShot SX70 HS (focal length in 35 mm film equivalent: 15 mm, saved image: size 1824 × 1824 pixels, saved format jpg), imaging was performed so that 4900 squares were included in an image of 1824 × 1824 pixels. Anti-fogging evaluation image: Taken 10 seconds after placing the sample. Reference image: Taken immediately after placing a polycarbonate substrate not treated with an anti-fogging agent (0 seconds after placement) (image O) and 10 seconds after placement (image N). Compression method: Compressed at a compression rate of 20% and resized to 820 × 820 pixels for output

[0196] [Calculation of anti-fogging index AFI] The anti-fogging index AFI was calculated by the following formula from the file size S1 when the anti-fogging evaluation image was compressed by the above compression method, the file size S2 when the image N was compressed by the above compression method, and the file size S0 when the image O was compressed by the above compression method. AFI=(S1 - S2)×10 / (S0 - S2)

[0197] (Water film uniformity index) Using the apparatus shown in Fig. 2, evaluation images and reference images were obtained under the following imaging conditions. Using the obtained evaluation images and reference images, the following image processing was performed to calculate the water film uniformity index.

[0198] [Imaging conditions] Sample image: Checkerboard pattern of black and white squares, side length of square 0.5 mm Water temperature: 40°C Distance D1: 1.5 cm Depth D2: 1 cm Distance D3: 17 cm (distance from the sample image to the central surface of the frontmost lens) Digital camera: Canon PowerShot SX70 HS (focal length in 35 mm film equivalent: 15 mm, saved image: size 1824×1824 pixels, saved format jpg), imaging was performed so that 4900 squares were included in the 1824×1824 pixel image. Evaluation image: Taken 40 seconds after the sample was placed. Reference image: Taken immediately after placing a polycarbonate substrate not treated with an anti-fogging agent (0 seconds after placing).

[0199] [Image processing] (1) Using image processing software (ImageJ), the evaluation image and the reference image were loaded and converted to 8-bit (Image→type→8-bit). (2) The boundary threshold was set to "90 - 255" (Image→Adjust→Threshold→set to "90 - 255"→apply). (3) Binarization was performed (Process→Binary→Make Binary). Set "Area" as the measurement condition (check Analyze → Set Measurements → Area). Using particle analysis, calculate the area of 1 pixel angle or more (Analyze → Analyze Particles → set "Size" to "1-Infinity", "Show" to "Outlines", check "Display results" and "Clear Results", and click OK). (6) From the information in (5) of the reference image, create a frequency distribution with an interval of 20 pixels in the range of 0 to 1000 pixels as the area distribution, and obtain the area range RA where the frequency is 5% or more of the total frequency. (7) From the information in (5) of the evaluation image, create a frequency distribution with an interval of 20 pixels in the range of 0 to 1000 pixels as the area distribution, and calculate the ratio (%) of the number of particles (frequency) included in the area range in (6) to the total number of particles (total frequency), and define this as the water film uniformity index WE.

[0200] Furthermore, the following evaluations were carried out.

[0201] (Water contact angle measurement) The water contact angle of the anti-fog film was measured. DropMaster DM-50 (manufactured by Kyowa Interface Science) was used for the measurement. The volume of the dropped water was 1 μL. The number of n was set to 3.

[0202] (Water film uniformity) Similar to when taking the evaluation image for the water film uniformity index, prepare a sample in a state where a water film is formed, conduct a transmission test using the following laser pointer, visually confirm the shape of the image projected on the wall, and evaluate the water film uniformity according to the following evaluation criteria. [Transmission test] Laser pointer: Sakura Creapath Rabbit Laser Pointer RX-5N Shape of the irradiated light: Linear Distance between the laser pointer and the sample: 2 cm Distance from the sample to the wall for projection: 13 cm Length of the projected line: Approximately 7 cm [Evaluation Criteria] Uniform: Even when the position of the laser pointer is moved, no change is observed in the shape of the projected line. Non-uniform: Depending on the position of the laser pointer, distortion is observed in the shape of the projected line. Note that Fig. 7 is a diagram showing the shape of the image projected onto the wall, where (A) is an example of the uniform case and (B) is an example of the non-uniform case.

[0203] [Water Resistance] The sample was immersed in pure water and placed in a thermostatic bath heated to 40°C, and heated for 120 h. After heating, the following steam test was conducted, and the presence or absence of fogging was visually observed. [Steam Test] Steam generated from a water bath set at a temperature of 40°C was applied to the anti-fog film of the sample for 10 seconds. The height of the (anti-fog film) of the sample was 1.5 cm from the water surface. The presence or absence of fogging was visually observed.

[0204] [Humidity Resistance] The sample was placed in a thermostatic bath heated to 50°C and heated for 120 h under the condition of 95% humidity. After heating, the steam test was conducted in the same manner as above, and the presence or absence of fogging was visually confirmed. During heating, the humidity was checked with a hygrometer at any time.

[0205] [Table 4] [Explanation of Symbols]

[0206] 1... Substrate, 2... Anti-fog agent, 3... Spray, 5... Anti-fog film, 10... Sample, 20... Water, 30... Sample image, 40... Digital camera, 101... Lens, 102... Anti-fog film, 103... Lamp housing, 104... Light source, 105... Reflector, S... Lamp chamber.

Claims

Claim 1. A antifogging agent comprising colloidal silica in the shape of a pearl necklace, at least one selected from the group consisting of a crosslinking agent, a binder, and a metal chelate, and a liquid medium, wherein the crosslinking agent is a silane coupling agent having a ureido group, the binder is cellulose, polyacrylic acid, a vinyl acetate pyrrolidone copolymer, glycerin, dextrin, or polyethylene glycol, the metal chelate is a zirconium chelate compound or a nickel chelate compound (except for those containing a siloxane binder other than the silane coupling agent, except when the silane coupling agent is included), and the water film uniformity index WE represented by the following formula (a) is 65% or more when a water film is formed on the main surface of the substrate treated with the antifogging agent. WE = (S / TS) × 100... (a) [In formula (a), TS represents the total of the area and frequency of the black regions shown in the area distribution generated from an evaluation image of 1824 × 1824 pixels in size, which is an image of a subject having a checkered pattern composed of a black square and a white square with a side length of 0.5 mm, taken through the substrate on which the water film is formed. S represents the total of the frequencies included in a predetermined area range in the area distribution. The predetermined area range represents the area range in which the frequency is 5% or more of the total frequency in the area distribution showing the area and frequency of the black regions generated from a reference image of 1824 × 1824 pixels in size, which is an image of the subject taken through the substrate. However, the distance between the subject and the substrate is 2.5 cm, and the position of the digital camera for photographing the subject is set such that 4900 black squares and white squares are included in the image of 1824 × 1824 pixels in size.]

2. The antifogging agent according to claim 1, wherein the antifogging index AFI represented by the following formula (b) is 7 or more when water vapor is brought into contact with the main surface of the substrate treated with the antifogging agent. AFI = (S1 - S2) × 10 / (S0 - S2)... (b) [In formula (b), S1 represents the file size when the anti-fogging evaluation image obtained by imaging the subject through the base material contacted with water vapor is compressed by a predetermined compression method; S2 represents the file size when the image N obtained by imaging the subject through the untreated base material contacted with water vapor is compressed by the predetermined compression method; and S0 represents the file size when the image O obtained by imaging the subject through the untreated base material is compressed by the predetermined compression method. However, the sizes of the anti-fogging evaluation image, the image N, and the image O are 1824×1824 pixels, the distance between the subject and the base material is 2.5 cm, the position of the digital camera for photographing the subject is set such that 4900 black squares and white squares are included in the image having a size of 1824×1824 pixels, and the predetermined compression method refers to compressing at a compression rate of 20% and resizing to 820×820 pixels.]

3. The anti-fogging agent according to claim 1 or 2, comprising the silane coupling agent having a ureido group.

4. [A method for preventing fogging of a vehicle lamp structure, wherein the inner surface of the lens provided in the vehicle lamp structure is treated with the anti-fogging agent according to any one of claims 1 to 3.]

Images