JPS61231035A - Antifogging treatment of cellulose plastic molding - Google Patents

Abstract

PURPOSE:To obtain the titled molding having and semi-permanent antifogging property, by immersing a cellulosic plastic molding in an CONSTITUTION:A cellulosic plastic molding (e.g., cellulose acetate plastic molding) is immersed, if requried, in an alcohol.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method of imparting antifogging properties to a cellulosic plastic molded article by immersing the same in an alkaline aqueous solution.

"Prior Art" A method of immersing a cellulose plastic molded product in an alkaline aqueous solution to impart antifogging properties to the same plastic molded product is disclosed in Japanese Patent Laid-Open No. 56-76 filed by the present applicant.
No. 454; Publication W - The method described in Japanese Patent Application Laid-Open No. 57-56151 and the method described in Japanese Utility Model Publication No. 59-25413 filed by another person are known.

These plastics to be treated in known methods,
The temperature and concentration of the alkaline aqueous solution used as the treatment solution, the treatment time,
The conditions for this are roughly as follows.

JP-A-56-76454; The acetate plastic base material is heated to a liquid temperature of 30 to 60°C.
4.7 to 5.6% by weight potassium hydroxide-sodium hydroxide aqueous solution (potassium hydroxide:sodium hydroxide ==3 to 1:1 weight ratio) for 5 to 60 minutes.

JP-A-57-56151 5 A self-suacetate butyrate or cellulose propionate base material is heated to a temperature of 4.7 to 5.6 at a liquid temperature of 40 to 80°C.
Weight% potassium hydroxide-sodium hydroxide aqueous solution (potassium hydroxide:sodium hydroxide-1!5 to 1:1
(weight ratio) for 30 to 120 minutes.

Utility Model Publication No. 59-25413; Underwater goggles made of cellulose plastic are prepared at a liquid temperature of 20 to 60°C.
, /N to 2N alkaline aqueous solution for 15 to 240 minutes.

"Problems to be Solved by the Invention" According to the inventor's subsequent research, the above-mentioned anti-fog treatment methods found in the prior art have achieved a certain degree of anti-fog performance. The degree of reproducibility was also extremely insufficient. In other words, when using conventional treatment methods, the anti-fog properties of the treated products vary even though they are treated under the same conditions, and even immediately after treatment, many products do not reach the practical level of anti-fog properties. did. In addition, many of the products that appeared to have practical antifogging properties immediately after treatment lost their antifogging properties over time. As a result of research to solve the above-mentioned problems in conventional treatment methods, the present inventor adopted harsh treatment conditions such as the concentration of the alkaline aqueous solution, the temperature of the alkaline aqueous solution, and the immersion time in the alkaline aqueous solution. In particular, research has led to the knowledge that it is possible to change semi-permanent anti-fogging properties with good reproducibility.Furthermore, as a result of research, it has been found that appropriate pre-treatment and post-treatment methods are required for such harsh treatments. As a result, we have arrived at the present invention.

``Means for solving the problems'' and ``effects'', that is, the present invention is:
Immerse for 1 to 2 hours in a 4 to 8N potassium hydroxide aqueous solution or a potassium hydroxide-sodium hydroxide aqueous solution in which less than half the equivalent of potassium hydroxide in the same aqueous solution is replaced with sodium hydroxide at ~80°C. 1 characterized by
Anti-fog treatment method for cellulose plastic molded products. and (2) a method for antifogging treatment of cellulose plastic molded products, which is characterized by immersing the cellulose plastic molded product in alcohol, and subsequently treating the cellulose plastic molded product at a liquid temperature of 40 to 80°C. . Here, cellulose-based plastic molded products include, for example, cellulose acetate-based, cellulose glopionate-based, and cellulose acetate-butyrate-based plastic molded products (molded products also include plate-shaped base materials). meaning (hereinafter the same). In order to make the processing conditions of the present invention more appropriate, specific numerical values are adopted within the range of the various conditions described above depending on the type of plastic to be treated. The immersion treatment time is 1 hour or more (however, pre-treatment with alcohol is required).
30 minutes or more), and set conditions such as liquid temperature, alkali concentration, etc. as severe as possible under these conditions. When a plastic molded product is subjected to harsh treatment to the extent that it does not deform, minute irregularities occur on the surface of the plastic to be treated, and the gloss of the surface changes slightly before and after the treatment. This change in gloss occurs in the direction of decreasing gloss from before to after treatment, but this decreased gloss can be reversed by post-treatment of immersing the treated product in inorganic acid, which has a negative effect on antifogging properties. can be reproduced without any adverse effects. Examples of the inorganic acid used in this post-treatment include various inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid.

The alcohol treatment in the invention (2) improves the wettability of the plastic molded article and is useful for shortening the treatment time during subsequent immersion in an alkaline aqueous solution. The alcohol for this pretreatment includes methyl alcohol 1. Lower alcohols such as ethyl alcohol and isopropyl alcohol are suitable; ◎Cellosolves, esters, ketones, such as ethylene glycol monomethyl ether, ethyl acetate, methyl ethyl ketone, dioxane, toluene, and benzene;
Solvents such as aromatic hydrocarbons are presumed to have similar effects, but according to actual experiments, these do not exhibit the same effects as the lower alcohols mentioned above.

"Examples" The present invention will now be explained in more detail with reference to Examples.

Examples 1 to 7 According to Table 1, various plastics were treated with alkali, washed with water, and then treated with acid.

Examples 8 to 14 According to Table 2, various plastics were treated with alcohol, then treated with alkali, washed with water, and then treated with acid.

Comparative Examples 1-1 to 3-3 In order to compare the treated products of the present invention obtained in Examples 1 to 3 and 8 to 10 described above with the antifogging test and optical property test described below, the treatments shown in Table 3 were carried out. A comparative product was prepared.

Table 3 Anti-fogging property test: r:rs 54oso-19as Compliant with "Test method for anti-clouding agent for eyeglasses".

A test piece 6a x 6a = is held in a temperature holding device, and a water vapor generating bottle is placed in a constant temperature water bath for this test piece. 2. Using an air pump while maintaining the temperature at 43±2°C. Air of oJ/wm is sent to contact one side of the test piece. On the other hand, cooling water at a temperature of 25±2° C. is sent to the other surface through a circulation device in an amount of 1.0±0.217 tU. This operation causes a temperature difference on the test surface, which may cause water droplets to form on the test surface. The anti-fog property was determined by measuring the time it took for these water droplets to drip down the test surface.

Table 4 shows the antifogging test results.

Table 4 Optical Properties Test The transmittance of light in the visible region of wavelength 400- was determined for each treated product using the product "Spectronic Nod" manufactured by Takatsu Seisakusho.

Table 5 shows the optical property test results.

"Effects of the Invention" According to the present invention described above, it is possible to impart semi-permanent antifogging properties to plastic molded products.

If the treated product of the present invention is used as it is, the surface will be dull and have a lot of diffused reflection, making it unsuitable for some applications, but such defects can be easily overcome by post-treatment with an inorganic acid. It is possible.

Claims (2)

[Claims] (1) Cellulose plastic molded product at a liquid temperature of 40 to
Immersion treatment for 1 to 2 hours at 80°C in a 4-8N potassium hydroxide aqueous solution or a potassium hydroxide-sodium hydroxide aqueous solution in which less than half the equivalent of potassium hydroxide in the same aqueous solution is replaced with sodium hydroxide. A method for antifogging treatment of cellulose plastic molded products, characterized by: (2) A cellulose plastic molded product is immersed in alcohol, and then 4N to 8
0.5 to 1 to a potassium hydroxide-sodium hydroxide aqueous solution in which less than half the equivalent of potassium hydroxide in the N potassium hydroxide aqueous solution or the same aqueous solution is replaced with sodium hydroxide.
．． A method for antifogging a cellulose-based plastic molded product, the method comprising immersing it for 5 hours.