KR19980066464A - Water-repellent glass having excellent durability and method for producing the same - Google Patents

Abstract

A mixed solution containing a metal alkoxide compound and an inorganic salt is applied to one side of a glass substrate to form a first layer and a mixed solution containing a fluoroalkylsilane compound is applied on the first layer to form a second Layer is formed, a method of preparing a solution for forming a metal oxide layer is simple, a heat treatment temperature is lower than a softening point of ordinary soda lime glass or a conventional method, It is possible to prevent the deformation of the glass base material, to use expensive equipment or to avoid troublesome process, and the water-repellent glass produced by this manufacturing method has high film strength and excellent durability.

Description

Water-repellent glass having excellent durability and method for producing the same

[Industrial Applications]

The present invention relates to a water-repellent glass having excellent durability and a process for producing the same. More specifically, the present invention relates to a water-repellent glass having excellent durability and silica, (Water-repellent glass) having a double-layer structure having a water-repellent layer formed by applying a fluoroalkylsilane on the base layer, and a method for manufacturing the same will be.

BACKGROUND ART [0002]

In general, the surface of glass has a contact angle of 20 to 30 °, which is lower than that of water. This inhomogeneous water film causes scattering of light, which can interfere with the driver's vision especially during rainy or nighttime driving. If the surface energy of the glass surface can be reduced, the attachment form of the water droplet can be rounded, So that most of the glass does not show wetting with water. Water-repellent glass is called a water-repellent glass, and if water-repellent glass is used in automobiles, it prevents distortions in the field of vision coming from a heterogeneous water film, so that a clear view can be secured to prevent accidents . In addition, water repellency can significantly inhibit the formation of fogging and the formation of frost in winter. In addition, there is an advantage that even if dirty foreign matter adheres, it can be easily removed.

In order to impart water repellency to the glass surface, the surface energy of the glass surface must be made low. For this purpose, it is required to form a substance having a low surface energy (hereinafter referred to as a water repellent agent) on the glass surface. The most widely used method of applying water repellent such as RAIN-X (Unelko Corp. USA, US 3579540) to glass is to apply water repellent to glass to impart water repellency. Generally, hydrocarbon-based compounds, silicone-based compounds, chlorine compounds, and fluorine compounds are used as water repellent agents. The critical surface tension of the hydrocarbon-based compound and the silicon-based compound is about 30 dyn / cm. On the other hand, a fluorinated alkyl compound containing a CF 3 group and a CF 2 group in the molecule (hereinafter referred to as Rf compound) has a critical surface tension of 20 dyn / cm or less and has properties of emitting not only water and polar solvents but also oil.

As the present water repellent agent, fluoroalkylsilane type water repellent agent exhibits the most excellent performance, which is rich in CF3 or CF2, which imparts low surface energy, and exhibits a structurally linear structure to increase the density of the water repellent This is because there are advantages. As described above, the water-repellent agent imparting water-repellent function to the glass is largely in contact with the silanol (OH) group on the glass surface to cause a strong siloxane (Si-O-Si) And a Rf group having a fluorocarbon group which imparts a hydrophobic property to the hydrophobic group.

As a method of forming the water-repellent function on the glass on a simple basis, first, a method of forming a fluoric polymer layer such as Teflon on the glass surface and a method of forming a layer of the fluoric compound directly on the glass surface using a fluorocarbon- (3) a method in which at least one silane compound capable of forming a siloxane bond by reaction with a hydroxyl group on the surface of the glass is substituted with a fluoroalkylsilane (FAS) A business card) is used. A method of directly applying various fluorine-based polymer compounds such as Teflon is problematic in that scratch resistance is weak and light transmittance of the glass itself is lowered. A method of forming a fluorine-based compound layer directly on a glass surface using a fluorocarbon-based gas is described in H. Yasuda et al. (Journal of Polymer Science, Part A; Polymer Chemistry, Vol. 30, 1731-1739 , 10, 2766-2773 (1994)), but further studies are required for practical applications. On the other hand, water repellency of glass surface using Rf compound is the most realistic approach and many proposals have been made for practical use. However, when these fluorine compounds are applied to general sodium lime glass, there is a problem that the water repellency is deteriorated according to the use time due to elution of alkali components in the glass. In addition, when the water repellent agent is directly applied to the flat glass surface, the water repellent agent is easily removed from the surface due to its smooth surface shape and relatively small adhesion area, so that durability and water repellent performance can not be maintained.

The above-mentioned problems must be taken more seriously in the case of glass which is in an environment-poor condition such as automobile glass. Therefore, the water-repellent function of the automobile glass is insufficient only by the direct treatment of the water-repellent agent, . Here, durability refers to resistance to abrasion and scratch, resistance to rain and wind and chemical components, resistance to light such as sunlight, and temperature resistance to four seasons. That is, the water-repellent function must last for a long time in order to have the durability so that the user can see the functional benefits of the water-repellent glass without inconvenience. It is a common phenomenon that the water repellent function does not exceed several weeks or months by simple treatment of the water repellent itself.

Efforts to improve the durability of the water-repellent glass have been improved in many ways by many engineers. In order to impart durability of the water-repellent film, the concept of a double treatment in which a lower layer film of a material having high adhesive strength and hardness is formed on the surface of the substrate to be treated before forming a water repellent film and a water repellent film of an Rf compound is formed thereon. Here, it is suggested that a silane coupling agent (for example, a silane coupling agent) which does not contain Rf is suitable for the lower layer film which is strongly adhered to the surface of the substrate to be treated and has high hardness, and that the upper layer film of the water repellent function uses an Rf compound. A water-repellent glass based on this basic concept is formed by first forming a solid silica layer on a glass substrate based on tetraethoxysilane (TEOS) and then forming a water repellent film composed of an Rf compound (Japanese Patent Application Laid-Open Nos. 5-146745, 4-132637, 4-288349, 4-249146, 4-160039 and EP-0545201) or TEOS and Rf compounds in advance, And a method for manufacturing water-repellent glass (Japanese Patent Application No. 7-157749, No. 7-291666).

A more advanced method of forming a durable water repellent film is to form surface irregularities on a solid ground layer. Such surface irregularities are induced by the increase of the surface area subjected to water repellency, the increase of the site of reaction, The water repellent agent remains for a long time even if the surface is slightly removed due to wear and tear on the part, so that the water repellent function lasts for a long time. (JP-A-4-124047, EP-476510A (JP-A-243874)) in which a substrate is immersed in dilute hydrofluoric acid to etch the surface, and second, (JP-A-6-116430, JP-A-4-124047, and EP-476510A1 (JP-A-243874)) in which a surface is etched using a metal oxide layer (JP-A-4-325446, JP-A-5-24885) in which polyethylene glycol and triethylene glycol monoethylether are mixed to form fine pores in the metal oxide layer, (JP-A-6-116430, JP-A-4-124047, EP-476510A1 (hereinafter referred to as " JP-A-6-116430 ") which induces surface roughness by the difference in the degree of decomposition at the time of firing by mixing metal alkoxides having different molecular weights JP-A-243874)).

However, the hydrofluoric acid etching method (IL-4-124046) used for increasing the durability on the surface of the glass is disadvantageous in that the increase of the abrasion resistance is not so great and the harmful hydrofluoric acid should be used. , There is a problem that large-scale application such as automobile glass is limited and costly equipment such as a vacuum reactor is required. The process (US 5268198) of adding fine particles to the surface of a metal alkoxide to form fine pores on the surface is not only a complicated process but also a small increase in performance. A recent method (US5413865) using at least two sols of different molecular weights is superior to other methods in improving durability such as abrasion resistance, but since the process is complicated such as preparing two or more sols separately, There is a difficulty in manufacturing a water-repellent glass of high quality. A common problem with the methods using metal alkoxides is that the base layer has a high heat treatment temperature of about 300 to 600 ° C, which can deteriorate the basic properties of tempered glass or laminated glass of an automobile.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the problems of the prior art as described above, and it is an object of the present invention to provide a method for manufacturing a metal oxide layer, Water-repellent glass which is low in manufacturing cost and low in manufacturing cost, can prevent deformation of a glass base material, is highly cost-effective, and has high film strength and excellent durability without requiring expensive equipment and a manufacturing method thereof.

1 to 4 are graphs showing the results of measurement of NaCl concentration using a secondary ion mass spectrometer (SIMS).

1 and 2: inorganic salt not added

3 and 4: Inorganic salt addition

In order to accomplish the object of the present invention, the present invention provides a method for forming a first layer by applying a mixed solution containing a metal alkoxide compound and an inorganic salt on a glass substrate to form a first layer, The present invention provides a water-repellent glass having durability and a method of producing the same, which is manufactured by forming a second layer by applying a mixed solution containing a compound.

The inorganic salt is preferably NaCl, NH4Cl, KNO3, NaNO3, CH3COONa or the like. It is preferable that the inorganic salt is homogeneously distributed in the first layer, And then heating the glass substrate at a temperature below the softening point of the glass substrate, that is, at a temperature of about 200 ° C. The pH of the mixed solution for forming the first layer is preferably 1.5 to 2.5, and the mixed solution for forming the first layer includes tetraethoxysilane, ethanol, an aqueous solution of an inorganic salt, and hydrochloric acid In this case, it is preferable that the above-mentioned inorganic salt is 3 to 5 parts by weight with respect to water as NaCl.

[Example]

In a representative embodiment

The water-repellent glass of the present invention can be produced by first coating a glass substrate with a first layer formed by applying a mixed solution containing a metal alkoxide compound, which is a silica underlayer having an excellent film strength, and an inorganic salt, A water-repellent agent such as an ethoxysilane compound is applied by a wet method to form a water-repellent layer. Here, the formation of the Silica underlayer was first performed by mixing tetraethoxysilane (Si (C2H5O) 4), ethanol and hydrochloric acid, respectively, to prepare a mixed solution, stirring the mixture at room temperature for about 2 hours, KNO3, NaNO3, CH3COONa and the like is added to distilled water having a concentration of about 0 to 7 parts by weight, and the mixture is stirred at room temperature for about 2 hours. In the solution thus prepared, all the inorganic salts are dissolved in the solution, and the precipitates of the inorganic salts are not observed. The added ethanol is used as a solvent, hydrochloric acid is used as a catalyst for hydrolysis and polymerization, and water is added for hydrolysis and polymerization. The solution is aged for several days in a thermostat maintained at about < RTI ID = 0.0 > 30 C. < / RTI > The pH value of the coating solution is preferably maintained at about 1.5 to 2.5. The glass substrate used for the coating uses ordinary soda lime plate glass, and a slide glass may be used. The coating can be done by a coating apparatus such as a motor-driven dip-coater, etc., and the sample is immersed in the aged coating solution and then pulled up at a speed of about 30 cm / min. The coated sample is dried at room temperature for a certain period of time and then heat-treated at a temperature of about 150 ° C to 500 ° C for about 30 minutes. Here, it is preferable that the temperature rise and temperature decrease conditions in the heat treatment furnace are set at about 7 캜 per minute. When the firing is performed at a temperature of 200 ° C or higher, alcohol as a solvent is completely volatilized and polycondensation in the silica layer is enabled to improve the hardness of the film, but no apparent increase in film strength is observed at temperatures above 200 ° C.

If the amount of added TEOS is too large, the coating state becomes undesirable. If the amount of TEOS is too small, the stability of the solution deteriorates and the state of the solution may deteriorate during storage for a long time. On the other hand, if the amount of the inorganic salt to be added is small, the abrasion resistance property of the coating layer is decreased and the alkali resistance property is also decreased, while the transparency of the coating layer is excellent. When the amount of the inorganic salt is more than about 5 parts by weight, abrasion resistance is improved, but white precipitates are formed in the solution and the coating layer, which interferes with the field of view. The effect of aging time is less than 2 days, hydrolysis is not progressed sufficiently, and when aging time is more than 3 days, no significant improvement in performance is observed over time. On the other hand, there is no change in the solution due to storage for more than 3 days, and as a result, the stability of the solution is excellent.

The repellent solution used as the second layer was prepared by mixing fluoroethoxysilane (CF3 (CF2) 7CH2CH2Si (OC2H9) 9), iso-propyl alcohol, hydrochloric acid (HCl) Hydrolysis and polycondensation reaction proceed. Here, distilled water is added in an amount as theoretically required for hydrolyzing the ethoxy group of the added fluoroethoxysilane, and hydrochloric acid is added as a catalyst promoting hydrolysis and polycondensation reaction. Isopropyl alcohol is added as a solvent. The reason for promoting the hydrolysis and the polycondensation reaction is to maximize the siloxane reaction (Si-O-Si) by promoting the reaction between the Rf group and the silanol group (OH) on the glass surface. CF3 (CF2) 7CH2CH2SiCH3 (Cl) 2, CF3CH2CH2SiCl3, CF3CH2CH2Si (OCH3) 3 and the like can be used as the Rf compound used in the water-repellent solution in addition to the fluoroethoxysilane. In addition to hydrochloric acid, nitric acid, acetic acid and the like can also be used as the catalyst. The water-repellent coating is performed under the same conditions as the silica coating. That is, the silica-treated glass sample is immersed in a water-repellent solution using a dip-coating apparatus, and then pulled up at a rate of 30 cm / min. The sample on which the foot fluid is applied is dried at a temperature of about 150 캜 for 30 minutes. When the temperature at the time of the water repellent treatment is 350 ° C or higher, the decomposition of the fluorocompounds is carried out, so that the water repellency is lost and the surface of the glass becomes cloudy.

Preferred Embodiment

Preferred embodiments and comparative examples of the present invention will be described. However, the following embodiments are only examples of the present invention showing the structure and effects of the present invention, and the present invention is not limited to the following embodiments.

Example 1

(Inorganic salt; effect of concentration of NaCl)

A silica sol mixed solution having the composition as shown in Table 1 was prepared. Water was added to each of the four kinds of sols by adding water having four NaCl compositions adjusted to be 1 part by weight, 3 parts by weight, 5 parts by weight and 7 parts by weight of NaCl as an inorganic salt, And aged for 2 days. The soda lime glass was cut into 25 × 7 × 1 mm and immersed in the sol solution for 30 seconds using dip coater and then pulled up at a speed of 30 cm / min.

TEOS ET-OH H2O (including NaCl) HCl Total 104 g 860 g 36 g 0.2 g 1000.2 g 10.4 parts by weight 86 parts by weight 3.6 parts by weight 0.02 parts by weight 100.02 parts by weight

After the deposition was completed, the sample was heat-treated at a temperature of 400 ° C. for 30 minutes, and the temperature was controlled at 7 ° C./min. The heat-treated samples were coated with the submerged solution under the above conditions using dip coater. Here, the foot fluid was used after mixing 3 g, 150 g, 1 g and 0.2 g of fluoroethoxysilane (CF 3 (CF 2) 7 CH 2 CH 2 Si (OC 2 H 5) 3), isopropyl alcohol, hydrochloric acid and distilled water respectively. The water-repellent treated sample was dried at a temperature of 150 캜 for 30 minutes to produce a water-repellent glass having a double-layer structure according to the present invention. The samples subjected to the water-repellent treatment were observed for initial contact angle, contact angle after 5000 times of abrasion test, alkali resistance, light resistance, acid resistance, heat resistance and the like.

Example 2

(Influence of firing temperature)

Except that the concentration of NaCl was changed to 3 parts by weight and the aging time was changed to 3 days. The firing temperature of the silica film was changed to 150 ° C., 200 ° C., 300 ° C., 400 ° C. and 500 ° C. .

Comparative Example 1

(When inorganic salt is not added)

The procedure of Example 1 was repeated except that NaCl-free water was added to the silica sol, and the aging time was changed to 1 day, 2 days, and 3 days.

Test Methods

The contact angles of the coated glass samples were measured and the abrasion resistance, alkali resistance, acid resistance and heat resistance were measured. The contact angle was measured by a sessile drop method using a contact angle meter (model CA-X, manufactured by Kyowa Interface Science Co., Ltd.), and the average value was measured five times at different positions. The abrasion resistance was measured by cutting the wiperblade of the automobile to a predetermined size, applying a load of 200 g / cm 2, and performing 5000 reciprocating tests at a reciprocating speed of about 2 seconds and measuring the contact angle. The alkali resistance test was performed by immersing the specimen in a 1N NaOH solution for 6 hours, taking out the sample, and measuring the contact angle. The acid resistance was measured by immersing the specimen in a 1N HCl solution for 6 hours, and then taking out the contact angle. The light resistance was evaluated by measuring the contact angle after holding the sample for 100 hours at a distance of 15 cm from the light source with a 1000 W Xenon lamp. The heat resistance was evaluated by measuring the contact angle by measuring the contact angle after immersing the specimen in boiling water for 2 hours.

Test result

* Effect of inorganic salt concentration in Example 1 *

(silica sol aging 2 days, silica layer heat treatment 400 ° C 30 minutes, water repellent layer heat treatment 150 ° C 30 minutes)

NaCl concentration (parts by weight) Initial contact angle Contact angle after 5000 times wear Alkali Acid resistance Light resistance Heat resistance One 105 103 101 105 104 103 3 110 109 104 109 109 109 5 110 105 103 108 108 108 7 110 105 102 109 108 108

* Effect of firing temperature of Example 2 *

(3 parts by weight of NaCl, aged for 3 days, heat-treated in a water-repellent layer at 150 DEG C for 30 minutes)

Temperature (℃) Initial contact angle Contact angle after 5000 times wear Alkali Acid resistance Light resistance Heat resistance 150 110 101 102 102 104 105 200 110 107 104 107 108 109 300 110 108 105 106 109 108 400 109 106 104 107 108 109 500 108 108 104 109 109 109

* When the inorganic salt of Comparative Example is not added *

(silica sol aging 2 days, silica layer heat treatment 400 ° C 30 minutes, water repellent layer heat treatment 150 ° C 30 minutes)

Aging days (days) Initial contact angle Contact angle after 5000 times wear Alkali Acid resistance Light resistance Heat resistance One 108 95 82 104 104 90 3 110 96 84 105 103 91 5 110 96 93 105 102 94

As can be seen from the test results of the above Examples and Comparative Examples, the effect of the firing temperature was increased as the temperature was higher. However, no significant performance difference was observed at temperatures above 200 ℃. Therefore, it is found that the inorganic salt addition method can reduce the processing cost by lowering the heat treatment temperature compared with other methods of heat treatment at 250 ° C to 600 ° C. The specimen to which the inorganic salt was added according to the example of the present invention was superior to the specimen to which the inorganic salt of the comparative example was not added, in terms of abrasion resistance, alkali resistance and light resistance. In other words, the specimen containing the inorganic salt was found to have excellent film strength despite the low heat treatment temperature. The concentration of added NaCl was measured by sputtering using a secondary ion mass spectrometer (SIMS) (Perkin-Elmer, PHI-7200 TOF-SIMS / SALI) Are shown in Figs. 1 to 4. Fig. Here, the sputtering speed was about 100 Å / min, but there was a slight difference depending on the state of the sample. Figs. 1 and 2 are samples in which no inorganic salt is added, and Fig. 3 and Fig. 4 are samples in which 7 parts by weight of an inorganic salt is added. FIGS. 1 and 3 show a sample treated with only a silica underlayer, and FIGS. 2 and 4 show samples treated up to a water repellent layer on a base layer. In each figure, the intersection of the Si and Na concentration lines is the boundary between the soda lime glass and the silica layer. When the inorganic salt is not added, the concentration of Na in the silica layer is lower and the concentration of Si is higher than that of soda lime glass. However, when NaCl was added, the concentration of Na was remarkably higher than that of the silica layer, and even after the water repellent treatment, it was found to be uniformly distributed in the coating layer. The inorganic salt added is uniformly distributed in the coating layer, which is considered to improve the film strength and durability. The role of the added inorganic salt appears to be to increase the charge sites of soda lime glass and silica so that the ions with opposite charges are more closely and firmly attached (The Chemistry of Silica, by Ralph K. ller, John Wiley Sons, 1979, p. 708-709). The addition of 3 to 5 parts by weight of the inorganic salt improves the performance. When the amount of the inorganic salt is more than that, precipitates appearing in the solution or coating layer show phase separation, and the transparency of the coating layer is lowered even though the performance is slightly improved there was.

Claims (10)

Glass substrates; A first layer comprising a metal alkoxide compound and an inorganic salt formed on the glass substrate; And A second layer comprising a fluoroalkylsilane compound formed over the first layer; . The water-repellent glass of claim 1, wherein the inorganic salt is selected from the group consisting of NaCl, NH4Cl, KNO3, NaNO3, and CH3COONa. The water-repellent glass according to claim 1, wherein the inorganic salt is homogeneously distributed in the first layer. Forming a first layer by applying a mixed solution containing a metal alkoxide compound and an inorganic salt on a glass substrate; And Applying a mixed solution containing a fluoroalkylsilane compound on the first layer to form a second layer; Wherein the water-repellent glass is a water-repellent glass. 5. The method of claim 4, wherein the inorganic salt is selected from the group consisting of NaCl, NH4Cl, KNO3, NaNO3, and CH3COONa. The method of manufacturing a water-repellent glass according to claim 4, further comprising the step of applying a mixed solution for forming the first layer and then heating the glass substrate to a temperature below the softening point of the glass base material. 5. The method of manufacturing a water-repellent glass according to claim 4, wherein the pH of the mixed solution for forming the first layer is 1.5 to 2.5. 5. The method of manufacturing a water repellent glass according to claim 4, wherein the mixed solution for forming the first layer comprises tetraethoxysilane, ethanol, an aqueous solution of an inorganic salt, and hydrochloric acid. The water-repellent glass of claim 8, wherein the inorganic salt is 3 to 5 parts by weight of water as NaCl. 5. The method according to claim 4, wherein the inorganic salt is homogeneously distributed in the first layer.