JP2005298656A - Glass-hydrophilizing agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a glass-hydrophilizing agent composed mainly of a polymer obtained from at least one compound selected from acrylates and an acrylamide to continuously exhibit stable properties even when being stored for a long period. <P>SOLUTION: This glass-hydrophilizing agent is prepared by adding a compound having pH buffering activity to the glass-hydrophilizing agent composed mainly of a polymer obtained from at least one compound selected from acrylates and an acrylamide. The pH buffering agent preferably contains benzoic acid. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

 The present invention relates to a glass hydrophilizing agent that prevents a drop in visibility by bringing water droplets adhering to a glass surface into a wet (water film) state when rainfall or condensation occurs.

 When rain or condensation occurs on the glass surface, for example, in automobile glass, water droplets adhering to the side mirror, side glass, and rear glass obstruct the field of view. Cause a significant drop. As a method for preventing this, there is a glass hydrophilizing agent for automobiles mainly composed of a water-soluble polymer (for example, see Patent Document 1).

The water-soluble polymer used for the glass hydrophilizing agent is preferably a polymer composed of at least one compound selected from acrylic esters or acrylamide from the viewpoint of transparency and water resistance (see, for example, Patent Document 2).
JP 2002-88298 A Japanese Patent Application No. 2003-33994

When the polymer comprising at least one compound selected from acrylates or acrylamides is used as a glass hydrophilizing agent after diluting with water, the performance of the glass hydrophilizing agent is very strongly dependent on the pH of the solution. . That is, when the pH changes, the solubility of the polymer may decrease, and a part of the polymer may gel, making it unstable as an aqueous solution, or changing the charge on the molecular surface.

Further, when using an aqueous solution of a polymer comprising at least one compound selected from acrylic esters or acrylamide as a glass hydrophilizing agent, a part of the polymer may be hydrolyzed when left at a temperature higher than room temperature for a long period of time. The pH of the aqueous solution may change. When the above-mentioned decrease in solubility occurs due to this pH change, the glass hydrophilizing agent becomes cloudy or gelation occurs in a part of the polymer, and in some cases, the advantage that the transparency characteristic of the polymer is high is high. Will be lost.

In addition, if the charge state of the polymer molecule changes due to a change in pH, it affects the electrostatic adhesion between the polymer and glass, which is a feature of the glass hydrophilizing agent using the polymer. The advantage of high water resistance is lost.

When using an aqueous solution of a polymer composed of at least one compound selected from acrylic acid esters or acrylamide as a glass hydrophilizing agent, it is extremely important to stably control the pH of the liquid agent in order to fully exhibit the performance. become.

  The present invention solves the problems related to pH change in long-term storage of a glass hydrophilizing agent mainly composed of a polymer composed of at least one compound selected from acrylic acid esters or acrylamide, and provides long-term storage. The purpose of the present invention is to provide a glass hydrophilizing agent that continues to exhibit stable performance.

 In order to solve the above-mentioned problem, in the present invention, a glass hydrophilizing agent containing as a main component a polymer comprising at least one compound selected from acrylates or acrylamides, and further comprising a pH buffering agent. A glass hydrophilizing agent is provided.

In a preferred embodiment of the present invention, there is provided a glass hydrophilizing agent characterized in that the buffer for the glass hydrophilizing agent contains benzoic acid.

 According to the present invention, a glass hydrophilizing agent can be stored for a long period of time by adding a pH buffer to a glass hydrophilizing agent comprising as a main component a polymer comprising at least one compound selected from acrylic esters or acrylamide. Even if it carries out, it becomes possible to suppress the pH change by chemical changes, such as a hydrolysis. As a result, deterioration of the glass hydrophilizing agent due to chemical changes such as hydrolysis can be minimized and stable performance can be exhibited over a long period of time.

According to the present invention, when benzoic acid is used as a pH buffer, in addition to pH buffer action, it also has an action as a preservative.

Examples of the acrylate esters include methyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate (meth) acrylic acid, and diethylaminopropyl. .

Examples of the pH buffer include a mixture of a weak alkali and an acid, a mixture of a weak acid and an alkali, and a mixture of a solution having an equimolar concentration of a conjugate acid-base, preferably succinic acid / sodium hydroxide. System buffer, citric acid / sodium citrate buffer, and benzoic acid aqueous solution. The concentration of the pH buffering agent is preferably 0.01 mol / L to 0.05 mol / L. If it is 0.01 mol / L or less, the pH buffering action may be lowered, and if it is 0.05 mol / L or more, the transparency of the glass surface after drying may be deteriorated.

The concentration of the glass hydrophilizing agent depends on the type and molecular weight of the polymer comprising at least one compound selected from the acrylates or acrylamides used, but is preferably 0.01 to 1% by weight. If it is less than 0.01% by weight, the resulting coating film becomes too thin and the water resistance decreases.
On the other hand, when the amount is more than 1% by weight, the resulting coating film may become thick and uneven, or the viscosity may become too high and handling may be difficult.

 EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these. As a polymer composed of at least one compound selected from acrylic esters or acrylamide, DS431 and DS4366 of Starlight PMC Co., Ltd. were used.

(Example 1)
While stirring, 1 part by weight of DS4366 was added to 99 parts by weight of citric acid / sodium citrate pH buffer adjusted to pH = 5.2 to obtain a transparent liquid.
(Example 2)
While stirring, 1 part by weight of DS43366 was added to 99 parts by weight of succinic acid / sodium hydroxide pH buffer adjusted to pH = 5.2 to obtain a transparent liquid.
(Example 3)
While stirring, 1 part by weight of DS4366 was dissolved in 99 parts by weight of an aqueous benzoic acid solution to obtain a transparent liquid.
Example 4
While stirring, 1 part by weight of DS431 was dissolved in 99 parts by weight of an aqueous benzoic acid solution to obtain a transparent liquid.
In each pH buffer, the concentrations of citric acid, succinic acid, and benzoic acid were each 0.01 mol / L.

(Comparative Example 1)
While stirring, 1 part by weight of DS4366 was dissolved in 99 parts by weight of ion-exchanged water to obtain a transparent liquid.
(Comparative Example 2)
While stirring, 1 part by weight of DS431 was dissolved in 99 parts by weight of ion-exchanged water to obtain a transparent liquid.

(Test method)
The glass hydrophilizing agents shown in Examples 1 to 6 and Comparative Examples 1 and 2 were placed in a glass bottle, and as a substitute for long-term storage, the pH was measured after being left in a constant temperature bath at 50 ° C. for 60 days. The liquid appearance and glass hydrophilization performance were confirmed and are shown in Table 1. Moreover, the change with time of pH is shown in FIG. 1 and FIG.

According to the present invention, by adding a pH buffering agent to a glass hydrophilizing agent using a polymer comprising at least one compound selected from acrylic esters or acrylamide, glass hydrophilization can be achieved even if stored for a long period of time. The pH of the agent was stable, and the performance as a glass hydrophilizing agent was not lost.

On the other hand, in the case where no pH buffer was added, the pH of the glass hydrophilizing agent was increased by long-term storage. As a result, a gelled product and a slightly reduced adhesiveness with glass were observed.

According to the present invention, when benzoic acid as a pH buffering agent is added to a glass hydrophilizing agent using a polymer composed of at least one compound selected from acrylates or acrylamides, in addition to pH buffering action, preserving The effect as an agent is also expressed. Since the polymer is an organic substance, when it is usually used in an aqueous solution, it is necessary to consider adding a preservative or the like separately, but it becomes unnecessary.

An example of the form of use of the glass hydrophilizing agent obtained in the present invention is to discharge the glass hydrophilizing agent from the container containing the glass hydrophilizing agent using a trigger spray, but good performance in other use forms as well. Needless to say.

It is the figure which showed the time-dependent change of pH value in Example 1 thru | or 3 of this invention, and the comparative example 1. It is the figure which showed the time-dependent change of the pH value in Example 4 and Comparative Example 2 of the present invention.

Claims (2)

A glass hydrophilizing agent comprising a polymer comprising at least one compound selected from acrylic esters or acrylamide, and further comprising a pH buffer. The glass hydrophilizing agent according to claim 1, wherein the pH buffer contains benzoic acid.

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