Recently, it has been increasingly required that the surface of a transparent base material such as glass is prevented from clouding and also that inner and outer walls, bathrooms, display surfaces, and so on are prevented from being polluted.
The phenomenon that a surface clouds is caused by that fine water droplets adhering to the surface irregularly reflect light. This problem is solved by a method, for example, 1) rendering the surface water-absorptive to absorb water droplets, 2) rendering the surface hydrophilic to spread water droplets (formation of a water film) and thereby prevent light from being irregularly reflected, or 3) heating the surface to prevent coagulation of water. In general, the method 1) has disadvantages of a sharp reduction in the anti-clouding properties after saturation and a lack of hardness, and the method 3) has a disadvantage of a high running cost, and therefore the method 2) tends to be preferred.
At the same time, regarding the requirement for improvement in prevention of pollution, attention has been focused on a method of rendering a surface hydrophilic to provide self-cleaning properties (pollution-preventing properties) in which rainfall, watering, or the like makes pollution (e.g., hydrophobic material in the air) float above, and thereby the pollution is efficiently removed (Non-Patent Documents 1 and 2).
The present inventors have already proposed a method of hydrophilizing a surface (Patent Document 1). According to the method, a film having very high hydrophilicity can be obtained and is preferably applied to the use for preventing clouding and pollution, but the adhesion of the film to inorganic materials such as glass is not necessarily high in some cases, and therefore further studies such as searching of primer are necessary in the case of inorganic materials.
As hydrophilization to obtain high adhesion to inorganic materials, it is known a method in which a surface of an inorganic hard coat layer is treated with a reactive silane coupling agent and then a reactive group remaining on the surface is grafted (react) with a hydrophilic monomer (Patent Documents 2 and 3). As similar methods, there are, for example, a method using a silane coupling agent having a mercapto group and a hydrophilic monomer having a functional group that has a carbon-carbon double bond (Patent Document 4), a method using a silane coupling agent having a functional group that has a carbon-carbon double bond and a hydrophilic monomer having a mercapto group (Patent Document 5), a method using a silane coupling agent having an amino group and a hydrophilic monomer having a functional group that has a carbon-carbon double bond (Patent Document 6), and a method using a silane coupling agent having a functional group that has a carbon-carbon double bond and a hydrophilic monomer having a functional group that reacts or interacts with the functional group having a carbon-carbon double bond as well as a mercapto group (Patent Documents 7 and 8).
In addition, there is, for example, a method in which after treatment with a silane coupling agent having a functional group that has a carbon-carbon double bond, the surface is treated with sulfuric acid to convert the carbon-carbon double bond remaining on the surface into a hydroxyethyl group for hydrophilization (Patent Documents 9 to 12).
In the methods in Patent Documents 2 to 8, hydrophilization is possible, but since tri- or less functional silane coupling agents are used, the crosslink densities are low, and the degrees of hardness are insufficient. Therefore, high abrasion resistance is difficult to be obtained. Similarly, also in the methods of Patent Documents 9 to 12, hydrophilization is possible, but the methods are difficult to provide high abrasion resistance and also have problems of safety and corrosion of apparatuses due to the sulfuric acid treatment.    Patent Document 1: WO 2007/064003    Patent Document 2: Japanese Unexamined Patent Application Publication No. 4-225301    Patent Document 3: Japanese Unexamined Patent Application Publication No. 8-259270    Patent Document 4: Japanese Unexamined Patent Application Publication No. 2003-5499    Patent Document 5: Japanese Unexamined Patent Application Publication No. 2000-104046    Patent Document 6: Japanese Unexamined Patent Application Publication No. 2007-313674    Patent Document 7: Japanese Unexamined Patent Application Publication No. 2001-194502    Patent Document 8: Japanese Unexamined Patent Application Publication No. 2001-194503    Patent Document 9: Japanese Unexamined Patent Application Publication No. 6-82605    Patent Document 10: Japanese Unexamined Patent Application Publication No. 5-341107    Patent Document 11: Japanese Unexamined Patent Application Publication No. 5-341108    Patent Document 12: Japanese Unexamined Patent Application Publication No. 6-88902    Non-Patent Document 1: KOBUNSHI (POLYMER), 44(5), p. 307    Non-Patent Document 2: MIRAI ZAIRYO (FUTURE MATERIAL), 2(1), pp. 36-41