JP7738419B2 - cleaning solution - Google Patents

Description

The present invention relates to a cleaning solution. In particular, it relates to a cleaning solution used to remove and dissolve dirt (scum) adhering to a dry film resist developing tank.

Benzyl alcohol, a type of aromatic alcohol, is often used as a paint stripper, but strippers that use only benzyl alcohol pose a high fire risk.
For this reason, a release agent containing benzyl alcohol, water, and a cellulose derivative has been proposed (Patent Document 1).
When the stripping agent described in Patent Document 1 was used to strip and dissolve dirt (scum) adhering to a dry film resist developing tank, both the stripping ability and the dissolving ability were not satisfactory.

International Publication No. 2018/179925

In light of the above-mentioned current situation, the present invention aims to provide a cleaning solution that is excellent in the effect of removing dirt (scum) adhering to dry film resist developing tanks (hereinafter sometimes referred to as "scum removal ability") and the effect of dissolving scum (hereinafter sometimes referred to as "scum solubility").

As a result of extensive research into resolving the above-mentioned problems, the inventors discovered that a cleaning solution containing a cellulose derivative that has a specified viscosity when made into a 2% aqueous solution, an organic carboxylic acid or a salt thereof, an aromatic alcohol, and water can resolve the above-mentioned problems, leading to the completion of the present invention.

That is, the cleaning solution of the present invention is a cleaning solution containing a cellulose derivative, an organic carboxylic acid or a salt thereof, an aromatic alcohol, and water, and is characterized in that the viscosity of a 2 mass % aqueous solution of the cellulose derivative is in the range of 0.1 to 2500 mPa s at 25°C.
The cellulose derivative is preferably at least one selected from carboxymethyl cellulose or a salt thereof, methyl cellulose, and hydroxypropyl methyl cellulose.
The aromatic alcohol is preferably at least one selected from benzyl alcohol and phenethyl alcohol.

This invention makes it possible to provide a cleaning solution with excellent scum removal and scum dissolving properties.

The cleaning solution of the present invention will be described in detail below.
In this specification, the term "to" indicating a range of values indicates a range that includes the values stated as the upper and lower limits. When a unit is stated only for the upper limit of a range of values, this means that the lower limit is expressed in the same unit as the upper limit.
In the numerical ranges described in stages in this specification, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages.
Furthermore, in the numerical ranges described in this specification, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples.
In this specification, the content or amount of each component in a composition means, unless otherwise specified, the total content or amount of the multiple substances present in the composition when multiple substances corresponding to each component are present in the composition.

<Cleaning solution>
The cleaning solution of the present invention contains a cellulose derivative having a specific viscosity when made into a 2% aqueous solution, an organic carboxylic acid or a salt thereof, an aromatic alcohol, and water, and has excellent scum removal and scum dissolving properties.
The reason for this is not clear, but is presumed as follows, taking the case where glycolic acid is used as the organic carboxylic acid as an example.
Because glycolic acid contains a carboxyl group, adding and mixing the cleaning solution of the present invention into a dry film resist developing tank acidifies the interior of the dry film resist developing tank, making the scum insoluble in water. In addition, because the cleaning solution has a hydrophobic property derived from the methylene group, the scum swells and becomes easily peeled off from the surface of the developing tank.
Furthermore, the use of a specific cellulose derivative allows the cellulose derivative to adsorb to the surface of the aromatic alcohol, exhibiting protective colloid properties, and allows the average particle size (droplets) of the aromatic alcohol to be adjusted to an appropriate size, making it easier to capture and dissolve the exfoliated scum.
On the other hand, when an emulsifier made of an anionic surfactant or a nonionic surfactant is used, the average particle size of the aromatic alcohol is small (1 μm or less) due to the formation of micelles, and the effect of capturing scum dirt is small. Also, when a cellulose derivative that does not satisfy the specified viscosity is used, the particle size of the aromatic alcohol becomes larger than when an emulsifier is used, but the effect of capturing scum is small, and it is estimated that the cleaning effect is insufficient.

The following explains each ingredient contained in the cleaning solution.

(A) Cellulose Derivative The cleaning liquid of the present invention contains a cellulose derivative. There are no particular limitations on the viscosity of a 2% aqueous solution of the cellulose derivative as long as it is in the range of 0.1 to 2500 mPa·s at 25°C.
Examples include carboxymethyl cellulose or a salt thereof, methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, butyl cellulose, propyl cellulose, etc. Among these, carboxymethyl cellulose or a salt thereof, methyl cellulose, and hydroxypropyl methyl cellulose are preferred, and carboxymethyl cellulose or a salt thereof is particularly preferred, in view of the wide variety of viscosity ranges of commercially available aqueous solutions and their easy availability.
The cellulose derivative may be used alone or in combination of two or more. Examples of the salt include potassium salt, sodium salt, and ammonium salt. The viscosity is measured using a Brookfield viscometer. When two or more cellulose derivatives are used, the viscosity of a 2% aqueous solution refers to the viscosity after mixing the cellulose derivatives.
It is preferable to use a cellulose derivative having a viscosity in a 2% aqueous solution in the range of 0.5 to 1500 mPa·s, more preferably 1.0 to 500 mPa·s, and particularly preferably 1.5 to 50 mPa·s.
By using a cellulose derivative having a viscosity of 0.1 mPa·s or more in a 2% aqueous solution, the dispersibility of the aromatic alcohol can be improved, and by using a cellulose derivative having a viscosity of 2500 mPa·s or less, the particle size of the aromatic alcohol can be controlled within an appropriate range.

The content of the cellulose derivative can be adjusted depending on the viscosity of the cleaning solution, but is preferably in the range of 0.05 to 10% by mass relative to the total amount of the cleaning solution of the present invention. A range of 0.1 to 3.0% by mass is more preferable. By incorporating a cellulose content of 0.05% by mass or more relative to the total amount of the cleaning solution of the present invention, the dispersibility of the aromatic alcohol can be increased and scum solubility can be improved. By incorporating a cellulose content of 10% by mass or less relative to the total amount of the cleaning solution of the present invention, the viscosity of the cleaning solution can be adjusted to an appropriate range, making it easy to mix with the dry film resist developer when it is introduced into the dry film resist developer tank. The viscosity of the cleaning solution will be described later.

(B) Organic Carboxylic Acid or Salt Thereof The cleaning solution of the present invention contains an organic carboxylic acid or a salt thereof. Examples include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, glycolic acid, lactic acid, 2-hydroxybutyric acid, 2-hydroxyisobutyric acid, citric acid, glyceric acid, malic acid, tartaric acid, methacrylic acid, and salts thereof. Among these, those having a hydroxy group are preferred because of their high ability to remove scum.
The organic carboxylic acid or its salt may be used alone or in combination of two or more thereof. Examples of the salt include potassium salt, sodium salt, and ammonium salt.

The content of the organic carboxylic acid or its salt is preferably in the range of 0.1 to 15% by mass, and more preferably in the range of 1.0 to 3.5% by mass, based on the total amount of the cleaning solution of the present invention. By ensuring that the content is within this range, when the solution is mixed into a dry film resist developing tank, the dry film resist developer in the dry film resist developing tank is neutralized, and scum adhering to the developing tank can be made insoluble in water. Furthermore, although some types of organic carboxylic acids may be considered deleterious substances under the Poisonous and Deleterious Substances Control Act (in the case of glycolic acid, those with a content exceeding 3.6%), a content within the above range is also preferable in that this is excluded.

(C) Aromatic Alcohol The cleaning solution of the present invention contains an aromatic alcohol. By containing an aromatic alcohol, scum insolubilized in water can be incorporated, thereby improving scum solubility. Examples of aromatic alcohols include benzyl alcohol, phenethyl alcohol, hydroxybenzyl alcohol, cinnamyl alcohol, p-anisyl alcohol, p-methylbenzyl alcohol, phenoxyethanol, and 2-benzyloxyethanol.
Among these, benzyl alcohol and phenethyl alcohol are preferred because they are liquid at room temperature, have low volatility and little odor, are easy to handle and store, and are commercially available at low cost and easy to obtain. Benzyl alcohol is particularly preferred. The aromatic alcohols may be used alone or in combination of two or more.

The content of the aromatic alcohol is preferably in the range of 10 to 80% by mass, more preferably 30 to 50% by mass, relative to the total amount of the cleaning solution of the present invention. By making the content of the aromatic alcohol 10% by mass or more relative to the total amount of the cleaning solution of the present invention, the aromatic alcohol can be stably dispersed, thereby achieving the expected effect of scum solubility. By making the content of the aromatic alcohol 80% by mass or less, the average particle size of the aromatic alcohol droplets can be adjusted, thereby maintaining scum solubility. Furthermore, if the content of the aromatic alcohol is too high, the concentration of the dissolved cellulose derivative in the aqueous phase increases, which increases the viscosity of the cleaning solution and makes it difficult to control.
By setting the content of aromatic alcohol to 40 mass% or less of the total amount of the cleaning solution of the present invention, there is an advantage in that it does not fall under the category of hazardous materials (Class 4 flammable liquid, Class 3 petroleum water-insoluble) under the Fire Service Act.

(D) Water The cleaning solution of the present invention contains water. By adding water, the cellulose derivative can be dissolved. Furthermore, the cellulose derivative adheres to the surface of the aromatic alcohol, making it miscible in water.
The water content is preferably in the range of 20 to 90% by mass, more preferably 60 to 80% by mass, based on the total amount of the cleaning solution of the present invention. By making the water content 20% by mass or more based on the total amount of the cleaning solution of the present invention, it is possible to expect that the cellulose derivative will be dissolved and that the water will act as a protective colloid for the aromatic alcohol, and by making the water content 90% by mass or less, it is possible to expect that the dispersibility of the aromatic alcohol will be appropriately maintained.

(Other ingredients)
In addition to the above-described components, the cleaning solution of the present invention may further contain various other components depending on the purpose, as long as the effects of the present invention are not impaired. Examples of other components include ester solvents, ketone solvents, hydrocarbon solvents, chelating agents, rust inhibitors, stabilizers, antifoaming agents, and preservatives.

The viscosity of the cleaning solution of the present invention is preferably in the range of 1 to 350 mPa·s at 25°C, and more preferably in the range of 3 to 100 mPa·s. By setting the viscosity to 1 to 350 mPa·s, it can be easily mixed with the dry film resist developer when placed in a dry film resist developing tank. The viscosity is measured at 25°C using a Brookfield viscometer.

When dispersed in the cleaning solution of the present invention, the average particle size of the aromatic alcohol is preferably in the range of 30 to 60 μm, and more preferably in the range of 40 to 55 μm. By setting the particle size in the range of 30 to 60 μm, it becomes easier to capture and dissolve the exfoliated scum.

<Method of manufacturing cleaning solution>
The method for producing the cleaning solution of the present invention is not particularly limited. For example, a method is exemplified in which a solution of a cellulose derivative dissolved in water is placed in a predetermined container, and an organic carboxylic acid or a salt thereof and an aromatic alcohol are added to the container and mixed. As a means for mixing, a method is exemplified in which a dissolver is used for mixing.

The present invention will be described in more detail below with reference to examples.
(Examples 1 to 17, Comparative Examples 1 to 6)
The components were placed in a designated container in the mass ratios shown in Table 1 and thoroughly mixed (stirred at 300 rpm for 60 minutes using a dissolver) to obtain cleaning solutions. The scum removal and scum solubility of the resulting cleaning solutions were evaluated. The average particle size of the aromatic alcohol in the cleaning solutions was also measured for Examples 1, 9-10, 16-17, and Comparative Examples 1-6.
"Unmeasurable" in Table 1 indicates that the washing liquid was too viscous to measure or that the particle size could not be measured due to separation during measurement.
Furthermore, the viscosity of the cleaning liquid was measured for Examples 1 to 10, Examples 16 and 17, and Comparative Examples 1 to 4.
The methods for evaluation and measurement will be described later.
The raw materials used are as follows:
(A) Cellulose derivatives (A1) Sodium carboxymethylcellulose (Cellogen (registered trademark) 5A, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., viscosity of 2% aqueous solution: 5 mPa·s)
(A2) Sodium carboxymethylcellulose (Cellogen (registered trademark) 7A, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., viscosity of 2% aqueous solution: 15 mPa·s)
(A3) Sodium carboxymethylcellulose (Cellogen (registered trademark) PR, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., viscosity of 2% aqueous solution: 70 mPa·s)
(A4) Sodium carboxymethylcellulose (Cellogen (registered trademark) WS-C, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., viscosity of 2% aqueous solution: 1300 mPa s)
(A5) Hydroxypropyl methylcellulose (Metolose (registered trademark) 60SH-15, manufactured by Shin-Etsu Chemical Co., Ltd., viscosity of 2% aqueous solution: 15 mPa s)
(A6) Hydroxypropyl methylcellulose (Metolose (registered trademark) 90SH-4000, manufactured by Shin-Etsu Chemical Co., Ltd., viscosity of 2% aqueous solution: 4000 mPa s)
(B) Organic carboxylic acid or salt thereof (B1) Glycolic acid (B2) Citric acid (B3) Methacrylic acid (B') Inorganic acid or salt thereof (B'1) Phosphoric acid (C) Aromatic alcohol (C1) Benzyl alcohol (C2) Phenethyl alcohol Emulsifier Anionic emulsifier (Hitenol (registered trademark) LA12 polyoxyethylene alkyl ether sulfate ester ammonium salt, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
Nonionic emulsifier (NOF Corporation, Blemmer (registered trademark) PLE1300 alkoxypolyethylene glycol methacrylate)

(Evaluation of scum removability)
Parts with scum stains attached thereto were taken out from a liquid resist developing apparatus and a dry film resist developing apparatus that had been used in an alkaline developing step for six months, and used as test specimens.
The test pieces were immersed in solutions prepared by diluting the cleaning solutions of the Examples and Comparative Examples five-fold with a developer (2% aqueous sodium carbonate solution), and stirred at 25°C for 60 minutes. The degree of removal of scum from the parts was then visually confirmed and evaluated according to the following criteria. The results are shown in Table 1.
Good: Scum removal rate is 90% or more
△: Scum removal rate is 50% or more but less than 90%. ×: Scum removal rate is less than 50%.

(Evaluation of scum solubility)
Scum stains were collected from a liquid resist developing apparatus and a dry film resist developing apparatus that had been used in an alkaline development process for six months and dried for two hours in a dryer at 105°C. 1 g of this dried scum was added to 100 g of a solution prepared by diluting each cleaning solution five times with a developer (2% aqueous sodium carbonate solution), and the mixture was stirred at 25°C for 60 minutes. After stirring, the cleaning solution was filtered through filter paper, and the scum dissolution rate (%) was calculated from the mass of scum remaining on the filter paper. The scum dissolution rate was evaluated according to the following criteria. The results are shown in Table 1.
◎: Dissolution rate is 90% or more. ○: Dissolution rate is 80% or more but less than 90%. △: Dissolution rate is 50% or more but less than 80%. ×: Dissolution rate is less than 50%.

(Measuring the average particle size of aromatic alcohol)
The average particle size of the aromatic alcohol dispersed in the cleaning solution was determined by dynamic light scattering using a particle size measuring system ELS-Z manufactured by Otsuka Electronics Co., Ltd.

(Effects of cellulose derivatives)
As shown in Table 1, Comparative Example 1, which used a cellulose derivative with a viscosity of 4000 mPa s in a 2% aqueous solution, had a practical level of scum removal ability but poor scum dissolving ability. Similar results were obtained in Comparative Examples 2 and 3, which used a reduced amount of cellulose derivative.
In contrast, Examples 1 to 7, which used cellulose derivatives with viscosities in a 2% aqueous solution ranging from 0.1 to 2500 mPa·s, showed favorable results in both scum removability and scum solubility. Furthermore, Examples 1 to 6, which used cellulose derivatives with lower viscosities in a 2% aqueous solution than Example 7, showed favorable results in scum removability. This is thought to be due to the lower viscosity of the cleaning solution in Examples 1 to 6. It was also found that Examples 1 to 5, which used cellulose derivatives with lower viscosities in a 2% aqueous solution than Example 6, exhibited superior scum solubility compared to Example 6. It was also found that Examples 1 and 2, which used cellulose derivatives with lower viscosities in a 2% aqueous solution than Example 3, exhibited particularly excellent scum solubility. Furthermore, a comparison of Example 2 and Example 8 reveals that Example 1, which used sodium carboxymethylcellulose, exhibited excellent scum solubility. A comparison of Example 15 and Example 16 reveals that Example 15, despite the addition of a smaller amount of cellulose derivative, exhibited similar effects in both scum removability and scum solubility.

(Effects of organic carboxylic acids)
As shown in Table 1, Comparative Example 4, which used phosphoric acid, an inorganic acid, showed inferior results in both scum removal and scum solubility compared to Examples 1, 9, and 10, which used organic carboxylic acids. It can be seen that Examples 1 and 9, which used organic carboxylic acids having hydroxy groups, were superior in both scum removal and scum solubility compared to Example 10, which used organic carboxylic acid without hydroxy groups.
Next, the effect of the amount of acid added was confirmed. Example 13, which is a deleterious substance under the Poisonous and Deleterious Substances Act, showed results equivalent to those of Example 1 in terms of scum removal and scum dissolution.

(The effects of aromatic alcohols)
It can be seen that Example 1, which used benzyl alcohol, is superior in scum solubility to Example 14, which used phenethyl alcohol.
It can also be seen that Example 16, in which the blending ratio of benzyl alcohol was increased, showed results in both scum removal and scum solubility equivalent to those of Example 1. It can also be seen that Example 17, in which the blending ratio of benzyl alcohol was reduced, showed inferior scum solubility compared to Example 1.

(Effects of emulsifiers)
It is clear that Comparative Examples 5 and 6, in which an emulsifier was used, are inferior to Example 1 in both scum removal and scum dissolution.

(Effect of average particle size of aromatic alcohol when dispersed in cleaning solution)
It can be seen that Comparative Examples 2 and 3, in which the viscosity of a 2% aqueous solution was 4000 mPa·s, all exhibited poor scum solubility. The average particle size of the aromatic alcohol in the cleaning solution during dispersion in Comparative Examples 2 and 3 was 2.2 and 9.4 μm, respectively, which is very small, and it is presumed that this was the reason for the poor scum solubility. Furthermore, in Comparative Example 4, in which an inorganic acid was used, and Comparative Examples 5 and 6, in which an emulsifier was used, the average particle size of the aromatic alcohol in the cleaning solution during dispersion was 86.8 μm, 0.2 μm, and 0.3 μm, respectively, resulting in poor scum removal and scum solubility.
In contrast, Examples 1, 9, 16, and 17, which exhibit good scum removal and scum dissolving properties, all have particle sizes in the range of 30 to 60 μm. Of these, Examples 1, 9, and 16, which have particle sizes of 40 μm or more, are also found to have extremely excellent scum dissolving properties.

Claims (4)

A cleaning solution for scum adhering to a dry film resist developing tank, the cleaning solution containing a cellulose derivative, an organic carboxylic acid or a salt thereof, an aromatic alcohol, and water, wherein the viscosity of a 2 mass % aqueous solution of the cellulose derivative is in the range of 0.1 to 500 mPa s at 25°C , and the blending ratio of the organic carboxylic acid or the salt thereof is in the range of 0.1 to 15 mass % with respect to the entire cleaning solution . 2. The method according to claim 1, wherein the cellulose derivative is at least one selected from the group consisting of carboxymethyl cellulose or a salt thereof, methyl cellulose, and hydroxypropyl methyl cellulose.
The cleaning solution described in 3. The cleaning solution according to claim 1, wherein the aromatic alcohol is at least one selected from the group consisting of benzyl alcohol and phenethyl alcohol. 4. The cleaning solution according to claim 1, wherein the aromatic alcohol has an average particle size in the range of 30 to 60 μm when dispersed in the cleaning solution.