JP2632833B2 - Anti-fog coating agent - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an antifogging coating for a plastic optical material, and is particularly suitable for antifogging of an optical lens or the like using a plastic material such as polycarbonate or acrylic.

[Prior Art] Various techniques are already known for antifogging of plastic optical materials. One is to coat the optical material with a hydrophilic coating film, reduce the surface tension of water, and perform anti-fog. However, the required properties are not limited to simple anti-fog. Water resistance of the coating is required. In addition, it is required that the anti-fogging property does not decrease even when the coating film is immersed in running water (hereinafter, this requirement is referred to as “flowing anti-fogging property”). An antifogging material having three properties of antifogging property, water resistance and running water antifogging property is not known.

[Problems of the Invention] An object of the present invention is to provide an antifogging coating agent excellent in antifogging property, water resistance and running water antifogging property.

[Constitution of the Invention] The anti-fogging coating agent of the present invention comprises acrylic acid 60 to
A copolymer containing 40 mol% and at least 40 to 60 mol% of a member of the group consisting of methyl acrylate and ethyl acrylate, and 30% of acrylic acid in the copolymer.
An active ingredient is obtained by neutralizing about 70% into an alkali metal salt and an unpolymerized amino resin raw material.

Here, neutralization of acrylic acid is performed with an alkali metal,
The neutralized product is an alkali metal salt of acrylic acid. Also, unpolymerized amino resin raw materials include modified melamine resin, melamine resin, urea resin, modified urea resin, guanamine resin,
There are unpolymerized resin raw materials such as aniline resin and sulfamide resin, and among them, unpolymerized resin raw materials such as modified melamine resin, melamine resin, urea resin, modified urea resin and guanamine resin are particularly preferable. The amount of the unpolymerized amino resin raw material is preferably 1/8 to 1 of the unpolymerized amino resin raw material with respect to the copolymer 1 in a weight ratio with respect to the acrylic copolymer. Here, the weight of the acrylic copolymer is indicated based on the weight before neutralization of acrylic acid.

Such a coating agent is used by dispersing it in a suitable solvent such as water, and after being applied to a plastic optical material,
The unpolymerized amino resin raw material is polymerized by heat treatment to complete the coating film.

Each component and element in the coating agent will be described. As the copolymer, a copolymer of acrylic acid and methyl acrylate or ethyl acrylate is used. When the acrylic acid content in the copolymer is increased, the antifogging property and running water antifogging property are increased, but the water resistance is reduced, and the copolymer is composed of 60 to 40 mol% of acrylic acid and 40 to 40 mol% of acrylic acid ester. Limited to those containing 60 mol%. Next, the hydrophilicity of the coating film is increased by partial neutralization of acrylic acid, and the antifogging property and anti-fogging property in flowing water are improved. However, if the neutralization ratio is unnecessarily increased, the water resistance of the coating film decreases, and the neutralization ratio is 30.
Limited to ~ 70%. In the case of simple neutralization of the copolymer, sufficient water resistance could not be obtained no matter how the composition or neutralization rate was controlled. The only means to increase the water resistance without deteriorating the anti-fogging property and running water anti-fogging property was to add an unpolymerized amino resin raw material. That is, when an unpolymerized amino resin raw material was added to the partially neutralized copolymer, and the resin was polymerized after coating, a coating film having water resistance, anti-fogging properties, and anti-fog properties was obtained. . Examples will be described below, but the present invention is not limited to these examples.

[Example] Preparation of coating agent Ethyl acrylate (EA) or methyl acrylate (MA) and acrylic acid were polymerized with a benzoyl peroxide polymerization initiator in a dioxane solvent and reacted under reflux to obtain a copolymer. A coalescence was obtained. The average molecular weight calculated from the intrinsic viscosity was one having an acrylic acid content of 50 mol%, and was 380,000 for acrylic acid-ethyl acrylate and 360,000 for acrylic acid-methyl acrylate.

While the copolymer was dispersed in the solvent, an aqueous alkali solution such as sodium hydroxide, potassium hydroxide, lithium hydroxide, or cesium hydroxide was added dropwise to partially neutralize acrylic acid. When neutralization was performed with calcium hydroxide, the copolymer gelled and did not become a coating agent. Next, an unpolymerized amino resin raw material such as hexamethoxymethylol melamine (an example of an unpolymerized modified melamine resin raw material with Cymel 303 manufactured by Mitsui Toatsu Chemicals, Inc., Cymel is a registered trademark) is dispersed in a solvent such as methanol. Added. The unpolymerized amino resin raw material may be changed within the range of unpolymerized resin raw materials such as melamine resin, urea resin, modified urea resin, guanamine resin, aniline resin, and sulfamide resin. However, when the unpolymerized amino resin raw material is a melamine resin, a modified melamine resin, a urea resin, a modified urea resin, or an unpolymerized resin raw material of a guanamine resin, it is preferable to obtain a material having excellent water resistance and scratch resistance. . In Examples, unpolymerized urea resin raw material "UFR65" manufactured by Mitsui Toatsu Chemical Co., Ltd. (UFR is a registered trademark) was used as an unpolymerized urea resin raw material.
Unpolymerized butylated urea resin material "Uban 10S-60" manufactured by Mitsui Toatsu Chemicals, Inc. as an unpolymerized modified urea resin material
(Yuban is a registered trademark of Mitsui Toatsu Chemical Co., Ltd.) and the same unpolymerized butylated benzoguanamine resin material "Symel 123" (Symel is a registered trademark) manufactured by Mitsui Toatsu Chemical Co., Ltd. as an unpolymerized guanamine resin material. Using.

A leveling agent composed of silicone oil was added to the reaction solution after the addition of the unpolymerized amino resin raw material, and the mixture was diluted with a solvent such as water to complete a coating agent.

Coating and Performance Evaluation A coating agent was coated on a polycarbonate lens having a diameter of 78 mm, air-dried and heated to complete a coating film. In this process, the unpolymerized amino resin raw material is polymerized. The heating conditions are 2 hours at 120 ° C for unpolymerized melamine resin raw material, 2 hours at 90-100 ° C for unpolymerized urea resin raw material, and 1.5 hours at 130-140 ° C for unpolymerized butylated urea resin raw material. In the case of unpolymerized butylated benzoguanamine resin raw material, 10
Two hours at 0-110 ° C. The finished coating film was subjected to four tests of antifogging property, water resistance, running water antifogging property and scratch resistance. All the results are evaluated in four ranks of A, B, C, and D, and are expressed as an average value of four samples.

For anti-fog properties, place the coated lens on a beaker filled with 45 ° C warm water in an atmosphere of 20 ° C and 65% RH,
The evaluation was based on the time required until the entire surface of the lens became cloudy. This time is rank A for 120 seconds or more, rank B for 60-120 seconds, 30
C rank was set for 60 seconds, and D rank was set for 30 seconds or less.

The water resistance was evaluated by immersing the lens in water at 30 ° C. for 30 minutes and determining whether the coating film had swelled. If the coating film has no abnormality and no swelling is observed, rank A; if partial swelling is observed, rank B; if approximately half of the coating film swells, rank C; Rank.

The anti-fogging property in running water was examined by immersing the coated lens in running water at 30 ° C. for 30 minutes, drying the lens, and evaluating the anti-fogging property again. The method for evaluating the antifogging property is the same as that described above, and the evaluation criteria are also the same.

Scratch resistance is made by reciprocating 3 times on a lens coated with # 000 steel wool with a load of 1 kgw,
The number of scratches was evaluated. Three or less scratches were ranked A, 4 to 10 were ranked B, 11 to 30 were ranked C, and 31 or more were ranked D. In each measurement, the samples coated with the same coating gave the same results.

Table 1 shows the properties of the coating agent obtained by mixing the unpolymerized amino resin raw material (hexamethoxymethylolmelamine) with the copolymer 4 at a weight ratio of 1. The results are shown in the table for the copolymer of ethyl acrylate and acrylic acid. The results are the same when the ethyl acrylate is changed to methyl acrylate, and the results are the same. Identical results were obtained. The neutralization was carried out with sodium hydroxide, but the results were all the same when an alkali metal hydroxide was used.

From Table 1, the following is clear. The preferred ranges are 30 to 70% for the neutralization ratio and 40 for the acrylic acid content, provided that a result of Rank B or higher is obtained for any of the antifogging property, water resistance and running water antifogging property. ~ 60 mol%.
When the neutralization rate is increased, the antifogging property and running water antifogging property are improved, but the water resistance is reduced (for example, see a 50% acrylic acid sample). If the neutralization rate is 70% or more, the water resistance is low (see the column for neutralization rate 75%), and if it is 30% or less, the antifogging property and running water antifogging property are insufficient. reference). Next, the acrylic acid content is limited to 40 to 60 mol%, and at 35%, the antifogging property is insufficient at any neutralization ratio. With an acrylic acid content of 65%, sufficient water resistance could not be obtained even if the neutralization ratio was lowered.
Although not shown in the table, the results were completely the same even when ethyl acrylate was changed to methyl acrylate.

* In the table, 1) indicates the anti-fogging property, 2) indicates the water resistance, and 3) indicates the result of the running water anti-fogging property. The neutralization was performed with sodium hydroxide.

(Unless otherwise specified, neutralization was carried out with sodium hydroxide). An attempt was made to neutralize with ammonia water instead of sodium hydroxide. Could not be used.

The unpolymerized amino resin raw material plays a large role in the water resistance of the coating agent. Table 2 shows the amounts and types of unpolymerized amino resin raw materials and the characteristics when changed. The copolymer was composed of 50 mol% of acrylic acid and 50 mol of ethyl acrylate.
Mole% and a neutralization rate of 50% were used.

* The evaluation method is the same as in Table 1, and the amino resin indicates an unpolymerized amino resin raw material.

The amount of addition is indicated by the weight ratio of the unpolymerized amino resin raw material to the copolymer, where the weight of the copolymer is 1, and the weight of the copolymer is the value before neutralization (the same applies hereinafter).

From the table, it is clear that, when the unpolymerized amino resin raw material is not added, only those having insufficient water resistance can be obtained even if the neutralization ratio and the acrylic acid content in the copolymer are set to optimal values. It is also apparent that modified melamine, melamine, urea, and guanamine are particularly preferable as the type of unpolymerized amino resin raw material.

Unpolymerized amino resin raw materials also contribute significantly to scratch resistance. Table 3 shows the results of this point. The scratch resistance is significantly improved by the addition of the unpolymerized amino resin raw material, and the order of the effect of the unpolymerized resin raw material on the scratch resistance matches the order of the effect on the water resistance. Also, regarding the scratch resistance, methyl acrylate is particularly equivalent to ethyl acrylate. However, those using propyl acrylate or butyl acrylate cannot be used because of low scratch resistance.

☆ In principle, the copolymer has a neutralization rate of 50% and acrylic acid of 50%.
%, 50% ethyl acrylate used. Sample 10 was obtained by changing ethyl acrylate in the copolymer to methyl acrylate. Sample 11 was obtained by changing ethyl acrylate to propyl acrylate. Was used.

[Effects of the Invention] According to the present invention, a coating agent excellent in antifogging property, water resistance and running water antifogging property can be obtained. In the present invention, in particular, by examining the acrylic acid content and the neutralization ratio in the copolymer, a coating agent having three conditions of water resistance, antifogging property and running water antifogging property is obtained, and unpolymerized amino resin By mixing with the raw materials, the water resistance is improved without impairing the anti-fogging property and running water anti-fogging property.

Claims (2)

(57) [Claims] 1. A copolymer containing 60 to 40 mol% of acrylic acid and 40 to 60 mol% of at least one member selected from the group consisting of methyl acrylate and ethyl acrylate. An antifogging coating agent comprising, as active ingredients, an alkali metal salt obtained by neutralizing 30 to 70% of acrylic acid and an unpolymerized amino resin raw material. 2. The coating agent for anti-fogging according to claim 1, wherein the mixing ratio of the unpolymerized amino resin raw material and the acrylic copolymer and the unpolymerized amino resin are based on the state before neutralization. Characterized by a weight ratio of 8: 1 to 1: 1 with the amino resin raw material,
Antifogging coating agent.