JPH08119678A - Production of water-repellent antifouling glass - Google Patents

Abstract

PURPOSE: To obtain a water-repellent antifouling glass excellent in durability by adsorbing NH3 and/or an amine on the surface of a glass and then coating the surface of the glass with fluoroalkylchlorosilane. CONSTITUTION: A glass substrate is set in a reactor after the surface is cleaned by washing and NH3 and/or vapor of an amine such as triethylamine is introduced into the reactor under about >=1mmHg vapor pressure and is adsorbed on the surface of the substrate by contact with the substrate for a prescribed time. The substrate is then taken out, washed with a solvent and set again in the reactor. The internal pressure of the reactor is reduced to about 10Torr, a fluoroakylchlorosilane represented by the formula R-Si(CH3 )3-1-m (X)1 (Cl)m [where R is a fluoroalkyl, X is OCH3 , OCOCH3 , OH, etc., (1) is 0-2 and (m) is 1-3], e.g. heptadecafluorodecyltrichlorosilane is introduced into the reactor and the surface of the substrate is coated with the fluoroalkylchlorosilane by CVD method under reduced pressure or other method to obtain the objective water-repellent antifouling glass excellent in durability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing water-repellent antifouling glass used as glass for automobiles or construction.

[0002]

2. Description of the Related Art When water repellency is imparted to the surface of glass articles used for windshields for construction, automobiles, lenses for optical components, and other glass products, 1) water droplets containing contaminants do not remain on the glass surface. It has the effect of preventing glass contamination and burning, 2) When water-repellent glass is used for windshields and side windows of automobiles, rainwater adhered to the glass surface is blown away by wind pressure even when driving in the rain, ensuring the driver's view Various effects are expected, such as improved driving safety.

As a method for producing such a water-repellent antifouling glass, a polydimethylsiloxane compound and other organic silicones, fluorine-containing silicone compounds, alkylsilane compounds, and further fluoroalkylsilane compounds are wet-coated (1). , A liquid phase adsorption method (2) or the like is used. Also, as the same liquid phase method, a sol-gel method (3) of coating a hydrolyzate of an alkoxysilane compound and a fluoroalkylsilane compound has already been put to practical use as glass for automobiles.

Further, the present inventors have found that a fluoroalkylan treatment by a vapor phase method can provide a monomolecular film having excellent water repellency and antifouling performance ((4) Japanese Patent Application No. 6-95).
119).

[0005]

Generally, (1)-
In the liquid phase method of (3), a large amount of waste liquid is generated during production, which is not only an environmental problem but also an extra cost for processing. Further, in the method (4), heating at about 80 ° C. is required to form a strong film. further,
In the liquid phase method of (1) to (3), heat treatment at 150 ° C. or higher is necessary to obtain a film having good durability. This heat treatment also causes a cost increase.

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that ammonia and / or amines are adsorbed on the glass surface in the first step and treated with fluoroalkylchlorosilane in the second step to make them strong at room temperature. It has been found that a water-repellent antifouling film can be formed on a glass substrate.

This mechanism of action can be explained as follows. First, ammonia and / or amines are adsorbed to Si-OH groups on the surface of silicate glass via hydrogen bonds. At this time, the polarization of the (Si) OH group proceeds. When the fluoroalkylchlorosilane is introduced in this state, the property that the O atom in the state activated by the polarization on the surface of the substrate nucleophilically attacks the Si atom of the fluoroalkylchlorosilane is enhanced, and thus the fluoroalkylchlorosilane is immobilized. It is considered that the reaction is significantly accelerated. Ammonia or amines in the form of gas or liquid is adsorbed on the surface of glass at room temperature or at, for example, 50 ° C. or lower by contacting for several seconds to several minutes. When the ammonia or amines are brought into contact with each other in the form of gas, the vapor pressure thereof is preferably 1 mmHg or more. When diluted with water or an organic solvent and contacted in a liquid form, the concentration is preferably 1 to 5% by weight. The amount of ammonia or amines to be adsorbed on the surface of the glass may be negligible, for example adsorbing a monolayer on the surface of the glass is sufficient.

The amines used in the present invention are not particularly limited, and any of primary-, secondary-, and tertiary-amines can be used, and aliphatic amines, aromatic amines, amides, Any of the cyclic amines can be used. The stronger the basicity, the stronger the hydrogen bond is formed with the Si-OH group, and the more reactive it is. Also, the lower the vapor pressure, the lower the vaporization temperature and the higher the basicity, the stronger the basic vapor pressure. Low triethylamine can be preferably used. A slight amount of ammonia or the hydrochloride of amines remains in the finally obtained film, but it does not affect the water repellency. It can be completely removed by heating above 200 ° C. or by drawing a high vacuum.

On the other hand, as a material for forming the water-repellent antifouling film, fluoroalkylchlorosilane which is excellent in chemical durability and can obtain a low surface free energy film can be preferably used. Fluoroalkylchlorosilane is (1)
One fluoroalkyl group (R) as shown in the formula,
It is a silane composed of 0 to 2 methyl groups and at least one functional group (X). R-Si (CH3) _3-lm (X) _l (Cl) _m (1) (wherein R: fluoroalkyl group, X: -OCH3,
-OC2H5, -OCOCH3, -OCOC2H5, or -OH, l is 0, 1 or 2, m is 1, 2
Or 3 and the sum of l and m is 1, 2 or 3.)

The methyl group (-CH3) of fluoroalkylchlorosilane is inactive and does not have a great influence on the effect of the fluoroalkyl group (R), but the larger the number of functional groups (X), the more easily it is immobilized. Therefore, the smaller the number of methyl groups (3-l-m), the better.
Most preferably m) is zero.

The fluoroalkyl group is a group in which some hydrogen atoms of the alkyl group are replaced with fluorine atoms, and is preferably represented by the formula (2). _{Rf: - (CH 2) 2} (CF 2) n CF 3 (2) ( where n is zero or a positive integer)

That is, in the linear alkyl group, a hydrogen atom bonded to a carbon atom on the terminal side excluding two carbon atoms on the silicon atom side is preferably replaced by a fluorine atom. For example _{- (CH 2) 2 CF 3} , - (CH 2) 2 (CF 2)
_{2 CF 3, - (CH 2} ) 2 (CF 2) 5 CF 3, - (CH 2)
₂ (CF ₂ ) ₇ CF _{3 and the} like, among which — (C
_{H 2) 2 (CF 2)} 5 CF 3, - (CH 2) 2 (CF 2) 7 CF 3
Is particularly preferable. The reason is that the compound is likely to exist stably due to the presence of — (CH ₂ ) ₂ — on the silicon atom side in the fluoroalkyl group.

The larger the molecular chain length of the fluoroalkyl group, the smaller the surface free energy, which is preferable. However, when the molecular chain length is too large, vapor pressure becomes high and vaporization tends to occur, which is not preferable. C per hit
The number of repetitions (n) of H2 unit is preferably 3 to 9, especially n =
7 is most preferred. The reason why the treating agent that can be used in the present invention must have a chlorine atom as a functional group is that the fluoroalkylchlorosilane undergoes an immobilization reaction when subjected to a nucleophilic attack by an activated surface O atom. This is because it is necessary for any atom in the fluoroalkylchlorosilane to be easily desorbed for the purpose. The number (m) of chlorine atoms per molecule may be any of 1 to 3, but in order to increase the strength of the obtained film, m = 3 that allows condensation between molecules is optimal. Any treatment agent can be used as long as it satisfies the above conditions, but for the reasons described above, heptadecafluorodecyltrichlorosilane (HFTS), hexadecafluorodecyltrichlorosilane (HDFDTCS), etc. Of the substances in which n in the formula (2) is 3 to 9 and m in the formula (1) is 1 to 3, heptadecafluorodecyltrichlorosilane (HFTS) is the best.

The method of forming the water-repellent antifouling layer is not particularly limited, and a known rubbing method, dipping method, or the like can be used, but from the viewpoint of forming a uniform film inside the porous structure, the reduced pressure CVD method is used. The vapor phase method such as is particularly effective.
The degree of vacuum during the CVD process may be set so that a sufficient vapor pressure of the fluorosilane-based material can be obtained. Therefore, about 10 Torr is usually sufficient, although it depends on the type of fluorosilane-based material used.

Since the reaction between the antifouling layer and the surface of the substrate proceeds at room temperature, it is not necessary to heat the substrate during the CVD process. Of course, heating may be used, but it should be 80 ° C or lower. This reaction is a dehydrochlorination reaction of fluorosilane having Si-OH groups and chlorine groups. Even if the thickness of the water-repellent antifouling film is very small, it is effective, and a monomolecular film is preferable.

[0016]

【Example】

Example 1 In order to clean the surface of a soda-lime glass substrate having a thickness of 3 mm and a size of 300 mm × 300 mm, UV / O _{3 was used.}
Washing (50 ° C.-30 minutes, oxygen supply amount = 0.1 NL / minute,
The distance between the substrate and the lamp was 5 mm, and UV ozone cleaner manufactured by Samco was used. Next, the glass substrate was set in the chamber, and 1 g of triethylamine (TEA) was placed in the reservoir connected to the chamber, and N ₂ gas was passed over the TEA while irradiating the reservoir with ultrasonic waves. TEA vapor was introduced into the chamber for about 60 seconds, and TEA vapor was brought into contact with and adsorbed on the substrate surface. Unadsorbed TEA was collected with a cold trapper attached to the chamber outlet. After removing the substrate from the chamber, thoroughly wash the inside of the chamber with ethanol, set the substrate in the chamber again, and depressurize the chamber kept at room temperature to about 10 Torr and then 50 μL (50 × 10 ^{− 3} CC) heptadecafluorodecyltrichlorosilane (HFTS, purity 98%
As described above, Toshiba Silicone) was injected into the chamber space with a syringe. By vacuuming for 1 hour after injection,
Unreacted HFTS was cold trapped. After returning to normal pressure, the substrate (Sample A) was taken out. The film thickness of HFTS attached to the substrate surface is about 15 angstroms, which corresponds to a monolayer. The chamber temperature was kept at 35 ° C. throughout the experiment.

Comparative Example 1 For comparison, a sample B-2 treated with HFTS without adsorbing TEA was prepared as follows. UV / O
_{3 The} cleaned glass substrate was set in the chamber and then depressurized to about 10 Torr. . After heating to 80 ℃, 50μ
L HFTS was injected with a syringe and heated for 1 hour. Furthermore, in order to remove unreacted HFTS, heating was continued at 100 ° C. for 1 hour while evacuation was performed, and sample B was obtained.

For comparison, a sample E treated with HFTS was prepared by the same procedure as in Example 1 except that TEA was not adsorbed.

Comparative Example 2 In order to investigate the difference in reactivity depending on the functional group of the treating agent, the same operation as in Example 1 was carried out except that heptadecafluorodecyltrimethoxysilane (HFTMS) was used instead of HFTS as the treating agent. Sample C was manufactured according to. Further, using the same HFTMS as the treating agent, Sample D was prepared by the same operation as in Comparative Example 1.

Since it is considered that the smaller the glass surface free energy is, the less water and stains are attached, the contact angle to water was adopted as an index of relative water repellency and stain resistance. Further, as one of the measures of the strength of the film, the change with time in the contact angle with respect to water when immersed in boiling water was examined. The results are shown in FIG. A decrease in contact angle is observed for all samples with increasing boiling water immersion time. However, although the sample A (Example 1) was treated at room temperature, the contact angle was reduced at a lower rate and the durability was superior to that of the sample B (Comparative Example 2) treated at 80 to 100 ° C. I understand. This result is considered to be because the surface immobilization reaction of HFTS was significantly promoted by the preadsorption of TEA. On the other hand, the water resistance of Sample C (Comparative Example 2) is about the same as that of Sample D (Comparative Example 2). This indicates that the effect of preadsorption of TEA cannot be obtained when the functional group of the water / fouling preventive agent is a methoxy group instead of a chlorine group. The initial contact angle of sample E was about 95 degrees, and the contact angles at boiling water immersion times of 2 hours and 4 hours were about 90 degrees and 80 degrees or less, respectively.

[0021]

As described above, according to the method for producing a water-repellent antifouling glass of the present invention, it is possible to obtain a strong water-repellent antifouling film having durability higher than that of the heat-treated sample despite the room temperature treatment. You can Further, as a film forming method, a reduced pressure CV is used.
When a gas phase method such as method D is used, not only is no waste liquid produced, but liquid management becomes easier. Therefore, the water-repellent antifouling glass produced by the method of the present invention can be suitably used as a windshield for automobiles and buildings.

[Brief description of drawings]

FIG. 1 is a graph showing the boiling time dependence of the contact angle of water with respect to the water-repellent antifouling glass of one example of the present invention.

[Drawing reference number]

 A Example of the present invention B, C, D Comparative example

Claims (4)

[Claims] 1. A method for producing water-repellent antifouling glass, which comprises adsorbing ammonia and / or amines on the glass surface, and then coating the glass surface with fluoroalkylchlorosilane. 2. The method for producing a water-repellent antifouling glass according to claim 1, wherein the amine is triethylamine. 3. The method for producing a water-repellent antifouling glass according to claim 1, wherein the fluoroalkylchlorosilane is fluoroalkyltrichlorosilane, and the fluoroalkylchlorosilane is coated in a gas phase. 4. The method for producing a water-repellent antifouling glass according to claim 3, wherein the fluoroalkyltrichlorosilane is heptadecafluorodecyltrichlorosilane.