JPS59217783A - Anti-fogging composition - Google Patents

Abstract

PURPOSE:An anti-fogging composition forming a film having improved durability and surface hardness, showing improved anti-fogging effect, obtained by blending polyvinyl alcohol with hydroxypivalic aldehyde or its dimer. CONSTITUTION:(A) 100pts.wt. polyvinyl alcohol is blended with (B) preferably 80-30pts.wt. hydroxypivalic aldehyde and/or its dimer, to give the desired composition. In order to form an anti-fogging film on a material to be processed by using this composition, preferably a catalyst such as oxalic acid, etc. is added to the composition, which is applied to the material to be processed such as transparent plate glass, etc., optionally heated, and cured. USE:Glass, lens of glasses, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an antifogging composition that forms an antifogging film with excellent durability.

Conventionally, various antifogging compositions have been studied and reported that form a film on the surface of transparent glass or plastic and provide an antifogging effect to the surface of glass or plastic.

Generally, in order to obtain an antifogging effect, it is necessary to contain a functional group having hygroscopicity or hydrophilicity, such as a hydroxyl group or an amino group, in the material molecule. Polyvinyl alcohol contains many hydroxyl groups in its molecules and is known to have excellent antifogging properties. However, on the other hand, a film formed from polyvinyl alcohol has a low surface hardness, swells and softens when exposed to a large amount of water, and cannot maintain its shape for a long period of time. Various efforts have been made to overcome these drawbacks, including partial acetalization of hydroxyl groups in polyvinyl alcohol with formaldehyde, esterification with phosphoric acid, and crosslinking with chelate compounds to improve the physical strength and durability of the film. Improvements are being made. In fact, it is possible to improve physical strength using these methods. However, on the other hand, as a result of the reaction with formaldehyde or phosphoric acid, the number of hydroxyl groups in polyvinyl alcohol decreases, and the antifogging effect also decreases significantly.

As a result of intensive research on antifogging methods using polyvinyl alcohol, the present inventor found that a composition using polyvinyl alcohol and hydroxypivalaldehyde in combination has excellent film durability and surface hardness, and has the excellent antifogging properties inherent to polyvinyl alcohol. It has been found that a film is formed that can be effective.

That is, the present invention relates to an antifogging composition prepared by mixing polyvinyl alcohol with hydroxypivalaldehyde and/or its dimer.

The reason why the composition according to the present invention has an excellent antifogging effect is that the antifogging composition of the present invention acetalizes the hydroxyl groups of polyvinyl alcohol with hydroxypivalaldehyde when heated, and the physical properties such as surface hardness of the film. On the other hand, the hydroxyl groups present in hydroxypivalaldehyde remain as they are even after acetalization, so the hydrophilicity hardly decreases, and it is presumed that it exhibits a good effect.

In order to form an antifogging film on a workpiece to which antifogging properties are to be imparted using the composition of the present invention, the antifogging composition of the present invention can be used directly or by adding a catalyst to the composition. , applied to the surface of the workpiece such as a transparent glass plate or plastic plate,
It can be obtained by heating and curing if necessary.

Hydroxypivalaldehyde used in this Q-mei is a substance with a melting point of 23°C, but when left to stand, it becomes a crystalline dimer of a cyclic hemiacecool type having a melting point of 90 to 95°C.

This dimer takes the form of a monomer in a molten state, and in an aqueous solution it assumes an equilibrium state in which the monomer and dimer coexist.

However, during the acetalization reaction with polyvinyl alcohol in the presence of an acid catalyst or by heating, it behaves as a monomer.

The amount of hydroxypivalaldehyde or its dimer used in the present invention is 110 parts by weight per 100 parts by weight of polyvinyl alcohol as hydroxypivalaldehyde.
The amount is from 10 parts by weight to 10 parts by weight, preferably from 80 parts to 30 parts by weight.

Methods for mixing polyvinyl alcohol and hydroxypivalaldehyde include directly dissolving them in water, mixing individual aqueous solutions prepared in advance, and mixing hydroxypivalaldehyde as an alcohol solution such as methanol or ethanol. can be given. Catalysts used in the composition of the present invention include acids such as hydrochloric acid, phosphoric acid, citric acid, para-toluenesulfonic acid, inorganic salts such as ammonium chloride and ammonium phosphate, and butylamine. Acid adducts of amino compounds such as hydrochloride and urea oxalate are effective, and the amount added is preferably 0.01 to 1 part by weight per 100 parts by weight of the composition of the present invention.

In the present invention, the conditions for heating the composition of the present invention after coating it on a glass plate or plastic plate, etc., vary depending on the type and amount of the catalyst, but are usually 60 to 1
Preferably, the temperature is 50° C. for 1 minute to 2 hours.

In order to improve the smoothness of the film, suitable additives can be further used in the antifogging composition of the present invention.

The antifogging film obtained by the composition of the present invention is made of glass,
It has extremely excellent film properties such as adhesion to plastics, hardness, scratch resistance, and long-term sustainability of antifogging effects.Furthermore, hydroxypivalaldehyde and its dimeric properties used in the present invention The body is an almost immaculate substance and does not have a pungent odor like formaldehyde.
It also has the advantage of being extremely good for the working environment throughout the entire process, including mixing and adjusting the composition and heating and curing, and can be applied to glass products such as glasses, eyeglass lenses, and mirrors, and plastic products such as goggles and plastic lenses. This composition is extremely useful in practice.

Examples of the present invention are shown below.

Example 1 5% aqueous solution of polyvinyl alcohol with a degree of polymerization of 1500 5
Hydroxypivalaldehyde dimer 1.5 to 0 c c
An aqueous solution was prepared by dissolving g. Dissolve 0.5 g of oxalic acid in this solution, apply it on a glass plate, and heat it at 80℃ for 2 hours.
It was heated and cured for 0 minutes. The resulting film was colorless and transparent, had a complete antifogging effect against supersaturated water vapor, and had excellent scratch resistance and adhesion.

For comparison, 5 cc of a 35% formaldehyde aqueous solution was added instead of the hydroxypivalaldehyde dimer.
The film obtained by the same treatment as above had poor adhesion to glass and peeled off.

Example 2 50 cc of 5% water/8 solution of polyvinyl alcohol with a degree of polymerization of 2000 was added in advance to 50 cc of 5% water/8% polyvinyl alcohol. A solution was prepared by mixing a 30% methanol solution IQcc of hydroxypivalaldehyde dimer that had been prepared.

Add 0.12 g of para-toluenesulfonic acid to this solution, apply it on a glass plate, heat it at 100°C for 20 minutes, and then heat it for 15 minutes.
The resulting film was heated and cured for 10 minutes at 0"C. The resulting film was slightly colored brown, but was transparent, had a complete antifogging effect, and had good surface hardness and adhesion.

35 instead of hydroxypivalaldehyde as a comparison.
Example 3: A glass plate obtained by adding 5 cc of % formaldehyde aqueous solution and performing the same treatment as above had almost no anti-protective effect. Water soluble? & 50 cc hydroxypivalaldehyde 1.
An aqueous solution prepared by adding 5 g of ammonium chloride and 0.11 g of ammonium chloride and melting it was applied to a transparent polycarbonate plate and heated at 80°C.
, for 20 minutes, and then heated and cured at 150° C. for 10 minutes.

The resulting film had a complete antifogging effect against supersaturated water vapor and had good adhesion.

Patent applicant: Mitsubishi Gas Chemical Co., Ltd. Representative Kazuyoshi Nagano

Claims (1)

[Claims] A heat protection composition comprising polyvinyl alcohol mixed with hydroxypivalaldehyde and/or its dimer.