JP7292748B2 - Coating remover - Google Patents

Description

The present invention relates to a coating stripper.

Since the coating deteriorates over time, repainting may be required. For example, structures such as bridges and ship bottoms require periodic repainting and repair.
When repainting and repairing, the deteriorated paint film may be peeled off. Conventionally, blasting and physical action using a power tool have been widely used to remove the deteriorated paint film. However, these methods are concerned about the scattering of dust and fragments. There is also concern about noise generated during processing.

Therefore, instead of removing the deteriorated coating film by physical action, there is a case where the deteriorated coating film is removed by chemical action using a paint film remover. As the coating film remover, a solvent-based type that contains no water and a non-chlorine solvent is the main component, or a water-based type that contains a solvent and water (typically, the water content is 5 to 60% by mass. degree) are known. Water-based paint film removers also include emulsion types in which a solvent is dispersed in water (or water in a solvent), and water and solvent are uniformly mixed via a compatibilizer or the like. It can be classified as a type.
In recent years, the demand for water-based paint film removers has increased due to legal regulations and environmental considerations.

Benzyl alcohol is widely used as a component of water-based paint film removers because of its excellent paint film peeling performance. On the other hand, demand for water-based paint removers containing no benzyl alcohol or containing only a small amount of benzyl alcohol is gradually increasing due to the increasing demand for legal regulations and environmental considerations.

Examples of conventional paint film removers include those described in Patent Documents 1 to 3.
Patent Document 1 describes a composition containing water, benzyl alcohol and sodium p-toluenesulfonate as agent A of a two-component coating stripping composition consisting of agent A and agent B.
US Pat. No. 6,200,003 describes a method for regenerating volatile organic paint carriers using a water-containing organic solvent solution containing N-methylpyrrolidone, a dibasic acid ester, a glycol ether and water.
Patent Document 3 describes a stripping agent composition containing a dibasic acid ester, a fatty acid monoester, an aliphatic hydrocarbon compound and/or an aromatic hydrocarbon compound.

However, since the composition described in Patent Document 1 contains a large amount of benzyl alcohol, it cannot necessarily meet the demands of legal regulations and environmental considerations. In addition, although the water-containing organic solvent solution described in Patent Document 2 does not contain benzyl alcohol, it cannot be said that the coating film stripping performance is sufficient when used as a coating film stripping agent. Furthermore, the release agent composition described in Patent Document 3 is classified as a solvent-based type, which is different from a water-based type.

JP 2017-095596 A JP-A-4-100511 JP 2021-054936 A

Although the above-mentioned demand for paint film removers is increasing, the component that can replace benzyl alcohol, which has excellent paint film peeling properties, generally has low affinity with water, and water-based paint film peeling using this The agent had problems such as causing two-layer separation. Thus, it has been very difficult to achieve both the absence of benzyl alcohol or a small content of benzyl alcohol and the maintenance of coating peelability and storage stability.

The present invention has been made in view of such circumstances. One of the objects of the present invention is to provide a water-based paint stripping agent that does not contain benzyl alcohol or that has good paint film stripping performance and storage stability even when the content is small.

In intensive research to solve the above problems, the present inventors found water (A), N-methylpyrrolidone (B), fatty acid monoester (C), dibasic acid ester (D), The coating film-stripping agent containing the sulfonic acid-type solubilizer (E) does not contain benzyl alcohol, or even if the content is small, the coating film-stripping performance is excellent and the storage stability is good. Furthermore, the present invention was completed as a result of finding that there was little sagging when applied to a coating film, and further research was carried out.

That is, the present invention relates to the following.
[1] Coating film containing water (A), N-methylpyrrolidone (B), fatty acid monoester (C), dibasic acid ester (D), and sulfonic acid type solubilizer (E) paint remover.
[2] The paint remover according to [1], containing 1 to 50% by mass of N-methylpyrrolidone (B).
[3] The coating remover according to [1] or [2], containing 1 to 50% by mass of fatty acid monoester (C).
[4] The paint film remover according to any one of [1] to [3], containing 1 to 60% by mass of the dibasic acid ester (D).

[5] The coating stripping agent according to any one of [1] to [4], containing 1 to 50% by mass of the sulfonic acid type solubilizer (E).
[6] The coating stripping agent according to any one of [1] to [5], wherein the sulfonic acid-type solubilizer (E) is a sulfonate compound.
[7] The paint remover according to any one of [1] to [6], wherein the sulfonic acid-type solubilizer (E) is a compound containing no aromatic ring or aromatic heterocycle.
[8] The coating remover according to any one of [1] to [7], which does not contain benzyl alcohol.

According to the present invention, benzyl alcohol is not contained, or even if it is contained, the content is small, and the coating film peeling performance and storage stability are good, and there is little dripping when applied to the coating film. A water-based type paint stripper is provided.

Hereinafter, embodiments of the present invention will be described in detail.
In this specification, the notation "X to Y" in the description of numerical ranges means X or more and Y or less, unless otherwise specified. For example, "1 to 5% by mass" means "1% by mass or more and 5% by mass or less".

<Paint remover>
The coating remover of the present invention comprises water (A), N-methylpyrrolidone (B), fatty acid monoester (C), dibasic acid ester (D), and sulfonic acid type solubilizer (E). and
The components contained or may be contained in the coating stripping agent of the present invention and the properties and physical properties of the coating stripping agent are described in more detail below.

[Water (A)]
The paint film remover of the present invention contains water (A). As a result, the coating remover of the present invention is superior in environmental performance to a solvent-based coating remover containing no water and containing a non-chlorine solvent as a main component.
The water may be tap water, distilled water, or the like, as long as the paint film-stripping agent exhibits good performance.
The content of water (A) in the paint film stripping agent is typically 5 to 60% by mass, preferably 5 to 55% by mass, more preferably 10 to 50% by mass, and still more preferably 10 to 45% by mass. %, particularly preferably 10 to 40% by weight.

[N-methylpyrrolidone (B)]
The coating stripping agent of the present invention contains N-methylpyrrolidone (B). This improves the permeability of the paint film stripping agent of the present invention into the paint film. The coating film permeated with the coating film stripping agent swells and softens, and is lifted from the substrate, making it easier to peel off.
From the viewpoint of compatibility between the permeability of the coating film stripping agent to the coating film and the coating film stripping performance, the content of N-methylpyrrolidone (B) in the coating film stripping agent is preferably 1 to 50% by mass, and more It is preferably 5 to 40% by mass, more preferably 10 to 35% by mass, and particularly preferably 15 to 30% by mass.

[Fatty acid monoester (C)]
The paint film remover of the present invention contains a fatty acid monoester (C). The fatty acid monoester (C) has a high affinity with the dibasic acid ester (D), which will be described later, and has the function of improving the permeability of the dibasic acid ester (D), which has excellent coating film peeling performance, into the coating film. This improves the permeability of the coating film-stripping agent of the present invention into the coating film and the coating-film stripping performance.
The fatty acid monoester (C) has neither a substituent capable of forming an anion such as a carboxylic acid group, a hydroxyl group or a sulfo group nor a substituent capable of forming a cation such as an amino group.
From the viewpoint of compatibility between the permeability of the coating film remover to the coating film and the coating film peeling performance, the content of the fatty acid monoester (C) in the coating film removing agent is preferably 1 to 50% by mass, more preferably is 5 to 40% by mass, more preferably 10 to 35% by mass, particularly preferably 15 to 30% by mass.

Examples of fatty acid monoesters (C) include ester compounds of saturated or unsaturated fatty acids and saturated or unsaturated fatty alcohols.
The saturated or unsaturated fatty acid moiety in the fatty acid monoester (C) preferably has 5 to 25 carbon atoms, more preferably 8 to 23 carbon atoms, still more preferably 10 to 21 carbon atoms, and particularly preferably 12 to 19 carbon atoms. be. The saturated or unsaturated fatty acid moieties may be linear, branched or cyclic. When it has an unsaturated fatty acid moiety, it may contain a double bond or triple bond as an unsaturated bond, and the number of double bonds or triple bonds contained is preferably 1 to 5, more preferably 1 to 4, and 1 ~3 is more preferred. The unsaturated bond contained in the unsaturated fatty acid moiety is more preferably a double bond.
These saturated or unsaturated fatty acid moieties preferably have no substituents.

The saturated or unsaturated aliphatic alcohol moiety in the fatty acid monoester (C) preferably has 1 to 15 carbon atoms, more preferably 1 to 10 carbon atoms, still more preferably 1 to 5 carbon atoms, and particularly preferably 1 to 3. The saturated or unsaturated fatty alcohol moiety may be linear, branched or cyclic. When it has an unsaturated aliphatic alcohol moiety, it may contain double bonds or triple bonds as unsaturated bonds, and the number of double bonds or triple bonds contained is preferably 1 to 2, more preferably 1. The unsaturated bond contained in the unsaturated aliphatic alcohol moiety is more preferably a double bond.
These saturated or unsaturated fatty alcohol moieties preferably have no substituents.

Specific examples of saturated fatty acid monoesters as the fatty acid monoester (C) include methyl hexanoate, ethyl hexanoate, butyl hexanoate, hexyl hexanoate, heptyl hexanoate, octyl hexanoate, methyl heptanoate, and ethyl heptanoate. , propyl heptanoate, butyl heptanoate, hexyl heptanoate, octyl heptanoate, methyl octanoate, ethyl octanoate, propyl octanoate, butyl octanoate, pentyl octanoate, hexyl octanoate, heptyl octanoate, octyl octanoate, nonane Methyl acid, ethyl nonanoate, propyl nonanoate, butyl nonanoate, pentyl nonanoate, heptyl nonanoate, methyl decanoate, ethyl decanoate, propyl decanoate, butyl decanoate, hexyl decanoate, heptyl decanoate, methyl dodecanoate , ethyl dodecanoate, propyl dodecanoate, butyl dodecanoate, hexyl dodecanoate, heptyl dodecanoate, octyl dodecanoate, methyl tetradecanoate, ethyl tetradecanoate, propyl tetradecanoate, butyl tetradecanoate, tetradecyl tetradecanoate, methyl palmitate, palmitin ethyl acetate, propyl palmitate, butyl palmitate, 2-ethylhexyl palmitate, methyl octadecanoate, ethyl octadecanoate, propyl octadecanoate, butyl octadecanoate, 2-ethylhexyl octadecanoate, octadecyl octadecanoate, methyl eicosanoate, and eicosane ethyl acetate.

Specific examples of unsaturated fatty acid monoesters as the fatty acid monoester (C) include methyl palmitoleate, ethyl palmitoleate, methyl oleate, ethyl oleate, propyl oleate, butyl oleate, pentyl oleate, and oleic acid. Heptyl, 2-ethylhexyl oleate, methyl elaidate, ethyl elaidate, propyl elaidate, butyl elaidate, pentyl elaidate, 2-ethylhexyl elaidate, methyl linoleate, ethyl linoleate, propyl linoleate, linoleic acid Isopropyl, butyl linoleate, pentyl linoleate, hexyl linoleate, heptyl linoleate, 2-ethylhexyl linoleate, methyl linolenate, ethyl linolenate, propyl linolenate, butyl linolenate, pentyl linolenate, hexyl linolenate, linolene heptyl acid, 2-ethylhexyl linolenate, methyl arachidonate, ethyl arachidonate, butyl arachidonate, 2-ethylhexyl arachidonate, methyl eicosenoate, ethyl eicosenoate, butyl eicosenoate, heptyl eicosenoate, eicosenoate-2- Ethylhexyl, methyl eicosapentaenoate, ethyl eicosapentaenoate, butyl eicosapentaenoate, 2-ethylhexyl eicosapentaenoate, methyl erucate, ethyl erucate, butyl erucate, 2-ethylhexyl erucate, methyl docosahexaenoate, docosahexaenoic acid Ethyl, butyl docosahexaenoate, 2-ethylhexyl docosahexaenoate, methyl ricinoleate, ethyl ricinoleate, butyl ricinoleate, heptyl ricinoleate, and 2-ethylhexyl ricinoleate.

The fatty acid monoester (C) may be naturally derived, and specific examples thereof include coconut oil fatty acid, palm oil fatty acid, rapeseed oil fatty acid, soybean oil fatty acid, hydrogenated soybean oil fatty acid, linseed oil. Fatty acids, tung oil fatty acids, tall oil fatty acids, dehydrated castor oil fatty acids, castor oil fatty acids, grape seed oil fatty acids, black cumin oil fatty acids, pumpkin kernel oil fatty acids, borage seed oil fatty acids, wheat germ oil fatty acids, rapeseed oil fatty acids, sunflower oil fatty acids , peanut oil fatty acid, apricot oil fatty acid, pistachio oil fatty acid, almond oil fatty acid, olive oil fatty acid, macadamia nut oil fatty acid, avocado oil fatty acid, sea buckthorn oil fatty acid, sesame oil fatty acid, hemp oil fatty acid, hazelnut oil fatty acid, primrose oil fatty acid, wild rose Monoesters obtained by esterifying acids such as oil fatty acid, safflower oil fatty acid, and walnut oil fatty acid, and biodiesel.
Fatty acid monoester (C) may be formed of a single compound, or may be a mixture of two or more compounds.

Of these, methyl decanoate, methyl tetradecanoate, methyl stearate, methyl linoleate, methyl linolenate, methyl oleate, and methyl palmitate, and mixtures of two or more thereof are preferred, and methyl linoleate , methyl oleate, and methyl palmitate, and mixtures of two or more thereof are more preferred.

[Dibasic acid ester (D)]
The paint film remover of the present invention contains a dibasic acid ester (D). The dibasic acid ester (D) is a component having a strong peeling effect of the paint film, and it works to penetrate the paint film together with the fatty acid monoester (C) to peel the paint film.
The dibasic acid ester (D) has neither a substituent capable of forming an anion such as a hydroxyl group or a sulfo group nor a substituent capable of forming a cation such as an amino group.
From the viewpoint of compatibility between the permeability of the coating film stripping agent to the coating film and the coating film peeling performance, the content of the dibasic acid ester (D) in the coating film stripping agent is preferably 1 to 60% by mass, more It is preferably 10 to 50% by mass, more preferably 15 to 45% by mass, particularly preferably 20 to 40% by mass.

Examples of the dibasic acid ester (D) include a saturated or unsaturated aliphatic dicarboxylic acid, or a dicarboxylic acid having an aromatic ring or an aromatic heterocyclic ring, a saturated or unsaturated aliphatic alcohol, or an aromatic ring or Examples include ester compounds with alcohols having aromatic heterocycles.
The saturated or unsaturated aliphatic dicarboxylic acid moiety in the dibasic acid ester (D) or the dicarboxylic acid moiety having an aromatic ring or an aromatic heterocyclic ring preferably has 2 to 20 carbon atoms, more preferably 2 to 15, more preferably 2-12, particularly preferably 2-10. If it has a saturated or unsaturated aliphatic dicarboxylic acid moiety, it may be linear, branched or cyclic. When it has an unsaturated aliphatic dicarboxylic acid moiety, it may contain a double bond or triple bond as an unsaturated bond, and the number of double bonds or triple bonds contained is preferably 1 to 5, more preferably 1 to 3. Preferably, 1 to 2 are more preferable. The unsaturated bond contained in the unsaturated aliphatic dicarboxylic acid moiety is more preferably a double bond.
These saturated or unsaturated aliphatic dicarboxylic acid moieties and dicarboxylic acid moieties having an aromatic ring or aromatic heterocyclic ring preferably have no substituents.

The saturated or unsaturated aliphatic alcohol moiety in the dibasic acid ester (D) or the alcohol moiety having an aromatic ring or aromatic heterocyclic ring preferably has 1 to 15 carbon atoms per alcohol moiety, It is more preferably 1-10, still more preferably 1-5, and most preferably 1-3. The saturated or unsaturated fatty alcohol moiety may be linear, branched or cyclic. When it has an unsaturated aliphatic alcohol moiety, it may contain a double bond or triple bond as an unsaturated bond, and the number of double bonds or triple bonds contained is preferably 1 to 2 per alcohol moiety. , 1 are more preferred. The unsaturated bond contained in the unsaturated aliphatic alcohol moiety is more preferably a double bond.
These saturated or unsaturated aliphatic alcohol moieties and alcohol moieties having aromatic or heteroaromatic rings preferably have no substituents.
Two saturated or unsaturated aliphatic alcohol moieties and/or alcohol moieties having an aromatic ring or an aromatic heterocyclic ring are included per molecule of the dibasic acid ester (D), which may be the same. , may be different.

Specific examples of the dibasic acid ester (D) include dimethyl succinate, dimethyl glutarate, dimethyl adipate, dimethyl phthalate, dimethyl maleate, diethyl succinate, diethyl glutarate, diethyl adipate, diethyl phthalate, Diethyl maleate, diisobutyl succinate, diisobutyl glutarate, diisobutyl adipate, diisobutyl phthalate, diisobutyl maleate, dibutyl succinate, dibutyl glutarate, dibutyl adipate, dibutyl phthalate, dibutyl maleate, dihexyl succinate, glutaric acid Dihexyl, dihexyl adipate, dihexyl phthalate, dihexyl maleate, di-2-ethylhexyl succinate, di-2-ethylhexyl glutarate, di-2-ethylhexyl adipate, di-2-ethylhexyl phthalate, and maleic acid Di-2-ethylhexyl may be mentioned.
The dibasic acid ester (D) may be formed by a single compound, or may be a mixture of two or more compounds.

Among these, diethyl succinate, diethyl glutarate, diethyl adipate, dimethyl succinate, dimethyl glutarate, and dimethyl adipate, and mixtures of two or more thereof are preferred, such as dimethyl succinate, dimethyl glutarate. , and dimethyl adipate, and mixtures of two or more thereof are more preferred.

[Sulfonic acid-type solubilizer (E)]
The coating stripping agent of the present invention contains a sulfonic acid type solubilizer (E). As a result, the above components (B) to (D) can be stably present in water, and the storage stability of the coating stripping agent of the present invention is improved.
From the viewpoint of storage stability, the content of the sulfonic acid-type solubilizer (E) in the coating film-stripping agent is preferably 1 to 50% by mass, more preferably 3 to 40% by mass, and still more preferably 5 to 35% by mass. % by weight, particularly preferably 10 to 30% by weight.

Examples of sulfonic acid-type solubilizers (E) include dialkylsulfodibasic acid compounds, alkanesulfonic acid compounds, alkenesulfonic acid compounds, hydroxyalkanesulfonic acid compounds, alkylbenzenesulfonic acid compounds, naphthalenesulfonic acid-formaldehyde condensates, alkyl naphthalenesulfonic acid compounds and N-alkyl-N-acyl tauric acid compounds. Moreover, the sulfonic acid-type solubilizer (E) may be a commercially available sulfonic acid-type surfactant.
These compounds are preferably sulfonate compounds. Examples of cations that constitute sulfonates include calcium, sodium, potassium and ammonium ions, with sodium ions being preferred.
The sulfonic acid-type solubilizer (E) is preferably a compound that does not contain an aromatic ring or aromatic heterocycle from the viewpoint of adverse effects on the environment and the human body.

Specific examples of the sulfonic acid-type solubilizer (E) include dialkylsulfodibasic acid compounds such as dioctyl sulfosuccinate, di-2-ethylhexyl sulfosuccinate, didecyl sulfosuccinate, and didodecyl sulfosuccinate, or salts thereof; alkanesulfonic acid compounds or salts thereof; alkenesulfonic acid compounds such as tetradecenesulfonic acid or salts thereof; hydroxyalkanesulfonic acid compounds such as 3-hydroxy-1-propanesulfonic acid or salts thereof; dodecylbenzenesulfonic acid, laurylbenzenesulfone Alkylbenzenesulfonic acid compounds or salts thereof such as acids; naphthalenesulfonic acid-formaldehyde condensates or salts thereof; alkylnaphthalenesulfonic acid compounds or salts thereof such as 7-dodecyl-2-naphthalenesulfonic acid; -alkyl-N-acyl tauric acid compounds or salts thereof.
The sulfonic acid-type solubilizer (E) may be composed of a single compound or a mixture of two or more compounds.

Among these, didecyl sodium sulfosuccinate, didodecyl sodium sulfosuccinate, dioctyl sodium sulfosuccinate, and sodium dodecylbenzenesulfonate, and mixtures of two or more thereof are preferred, including didecyl sodium sulfosuccinate and sulfosuccinic acid. More preferred are didodecyl sodium and dioctyl sodium sulfosuccinate and mixtures of two or more thereof.

[Other ingredients]
The paint film remover of the present invention may or may not contain components other than those described above.
For example, the paint film stripping agent of the present embodiment may contain an inorganic acid and/or an inorganic alkali, an organic acid and/or an organic alkali for the purpose of pH adjustment or the like. In addition, dyes and/or pigments for coloring purposes, extender pigments, perfumes for smelling purposes, rust inhibitors, antifoaming agents, surfactants, wetting agents for coating films, and polyolefins to prevent evaporation of active ingredients. Waxes, flame retardants, thickeners, co-solvents, and the like may also be included.

However, in a preferred embodiment, the inorganic acid content in the paint film-stripping agent is 0.5% by mass or less, and the inorganic alkali content in the paint film-stripping agent is 0.5% by mass or less. It is preferable that the content of the organic acid and/or the organic alkali is also about the same.

Moreover, when there are requirements such as legal regulations and environmental considerations, it is preferable that the paint remover of the present invention does not contain benzyl alcohol. When benzyl alcohol is contained, the content is preferably less than 20% by mass, more preferably less than 10% by mass, even more preferably less than 5% by mass, and less than 3% by mass. It is particularly preferred and most preferably less than 1% by weight.

[Physical properties, properties]
The paint film-stripping agent of the present invention preferably maintains a transparent or cloudy state for 1 minute or more without immediately separating into two layers after stopping stirring even before adding a thickener. In this way, even if the viscosity is low, if the coating film remover can maintain a transparent or cloudy state for a certain period of time after stirring is stopped, the work of adding additional components as necessary and the application to the coating film work can be performed smoothly.
As described above, the coating film-stripping agent of the present invention can be used without any problem as long as it can maintain a transparent or cloudy state for a certain period of time. By adjusting the amount of (E), a desired state of either transparency or cloudiness can be obtained.

The coating stripping agent of the present invention has excellent storage stability at room temperature, and even if slight supernatant liquid is observed after storage, it can be immediately returned to a homogeneous state by simple stirring.

The paint film remover of the present invention causes little sagging even when applied to a vertical surface. This property is thought to be due to the fact that the paint film remover is sufficiently homogenized or dispersed, so the liquid component due to layer separation does not come out to the interface, and the applied paint film remover does not easily slip off. be done. This eliminates the need to add an excessive amount of thickening agent for the purpose of preventing dripping, which is advantageous in terms of workability and economy.
In addition, when the paint film remover applied to the vertical surface drips, the paint film remover cannot penetrate sufficiently into the part where the drip occurs, and the peeling performance against the paint film cannot be sufficiently exhibited. Can not. Therefore, the coating film-stripping agent of the present invention, which causes little sagging, is particularly excellent in stripping performance for coatings on vertical surfaces.

The paint film remover of the present invention is produced, for example, by putting the above components in a container and mixing them. For mixing, for example, a commercially available stirrer or the like can be used. In particular, when the viscosity of the coating remover is high, the coating remover in which each component is uniformly dissolved/dispersed can be produced by appropriately selecting the diameter of the stirring blade and the diameter of the container. If a stirring blade that is too small compared to the size of the container is used, there is a risk that sufficient mixing will not occur near the wall surface of the container. preferable.

The coating remover of the present invention is manufactured and distributed in a concentrated form, and may be diluted immediately before use. For example, a paint film stripping agent having a low water content may be prepared and diluted with water immediately prior to use.

<How to use the coating film remover (method for removing the coating film)>
There are no particular restrictions on the method of using the paint film remover of the present invention.
Typically, first, a coating stripper is applied to the coating to be stripped. As a coating method, a brush, a roller, a spray, or the like can be used. Then, the coating film remover is permeated into the coating film. As a result, the component of the coating film-stripping agent that permeates weakens the adhesion of the coating film (resin) to the substrate, or swells and softens the coating film. The time for which the coating film remover is brought into contact with the coating film may be appropriately adjusted according to the type and thickness of the coating film and/or the environmental temperature during coating. The contact time is, for example, about 1 to 24 hours. After that, the coating film is removed by a scraper or the like.
Since the paint film remover of the present invention is prevented from sagging, it tends to remain on surfaces that are not horizontal to the ground for a long time. As a result, it is possible to obtain good peeling properties even when peeling off coatings from structures such as bridges.

The coating stripping agent of the present invention is preferably used for stripping various types of coatings. Specifically, it exhibits good peelability in various types of coating films such as epoxy paints, urethane paints, melamine baking paints, acrylic baking paints, polyester powder paints, lacquer paints, and exterior wall materials. It can be said that one of the characteristics of the coating film-stripping agent of the present invention is that such various types of coating films can be easily peeled off.

Although the embodiments of the present invention have been described above, these are examples of the present invention, and various configurations other than those described above can be adopted. Moreover, the present invention is not limited to the above-described embodiments, and includes modifications, improvements, etc. within the scope of achieving the object of the present invention.

Embodiments of the present invention will be described in detail based on examples and comparative examples. It should be noted that the invention is not limited to the examples only.

<Production of coating remover>
(Example 1)
35 parts by mass of water, 10 parts by mass of N-methylpyrrolidone, 15 parts by mass of dibasic acid ester, 10 parts by mass of methyl oleate, and 10 parts by mass of dioctyl sodium sulfosuccinate were added to a vessel and stirred with a disper. After that, 4 parts by mass of fumed silica was added while maintaining the stirring state, and the mixture was stirred to obtain the desired coating film-stripping agent.

(Examples 2 to 19, Comparative Examples 1 to 7)
A paint stripping agent was produced in the same manner as in Example 1, except that each component and its amount were as shown in the table below.

(Details of raw materials)
The details of the raw materials used for producing the paint film removers of Examples and Comparative Examples are as follows.
· N-methylpyrrolidone: manufactured by Mitsubishi Chemical Corporation · Dibasic acid ester: manufactured by Sankyo Chemical Co., Ltd., trade name: No. 23 ester (mixture of dimethyl succinate, dimethyl glutarate and dimethyl adipate)
・Methyl oleate (fatty acid monoester): manufactured by Kanto Chemical Co., Ltd. ・Methyl palmitate (fatty acid monoester): manufactured by Kanto Chemical Co., Ltd. ・Ethyl lactate (auxiliary solvent): manufactured by Kanto Chemical Co., Ltd.

・Sodium dioctyl sulfosuccinate (solubilizing agent): manufactured by Tokyo Chemical Industry Co., Ltd. ・Sodium dodecylbenzenesulfonate (solubilizing agent): manufactured by Sigma-Aldrich ・Polyoxyalkylene allyl phenyl ether sulfate ・Na (solubilizing of comparative example Agent): Takemoto Oil Co., Ltd., trade name: Nucalgen P-205S30, active ingredient 30%, water 70%
· Polyoxyalkylene alkenyl ether (comparative solubilizer): manufactured by Kao Corporation, trade name: Ramtel PD-420
・ Sorbitan monooleate (comparative solubilizer): manufactured by Kao Corporation, trade name: Rhodol AO-10V
・ Fumed silica (thickener): manufactured by Nippon Aerosil Co., Ltd., trade name: Aerosil 300

<Evaluation of liquid transparency>
During the production of the paint film stripping agent described above, the stirring was stopped at the stage before adding the fumed silica (thickener), and the transparency of the liquid immediately after was visually evaluated. At the stage before adding the thickener and adjusting the viscosity, if the two layers do not separate within 1 minute after the stirring is stopped, it can be said that the stability is suitable for practical use.
A: No turbidity, transparent state maintained for 1 minute or longer B: Cloudy state maintained for 1 minute or longer C: Cloudy immediately after stirring stopped, but oil layer and water before 1 minute elapsed begins to separate into two layers

<Evaluation of storage stability>
The paint film remover was placed in a transparent bottle and allowed to stand in an atmosphere of 25° C. for 24 hours, and the change in state was visually evaluated.
◎ (Very good): No change 〇 (Good): A slight amount of supernatant liquid is observed, but it can be easily returned to a uniform state by simple stirring such as shaking the container × (Bad): Generation of supernatant liquid It returns to a homogeneous state temporarily by sufficient stirring, but separation of the supernatant liquid can be seen again before 1 minute has elapsed after stopping stirring.

<Evaluation of dripping property and peeling performance>
Exterior wall materials and coated metal plates obtained or prepared as described below were each coated with the coating film remover of Examples or Comparative Examples by the methods described below, and evaluated.

Exterior wall material Exterior wall material with a coating film obtained through a trading company was prepared as a sample. The thickness of the coating film was about 500 μm at the thinnest portion and about 3000 μm at the thickest portion.

・ Metal coated plate A4 size cold-rolled steel plate (standard: SPCC-SD, width 210 mm, length 297 mm, thickness 0.8 mm), one-component curing epoxy resin undercoat (product name: Stark (registered trademark) E Primer one-liquid quick-drying α White, manufactured by Natoco Co., Ltd.) was diluted with thinner and applied. After standing for 30 minutes in an atmosphere of 20° C., a white two-component curing urethane paint (product name: Stark (registered trademark) 1, manufactured by Natoco Co., Ltd.) is mixed in the main agent: curing agent ratio described in the catalog, It was appropriately diluted with thinner and coated so that the dry film thickness would be 80 μm. After that, it was left in an atmosphere of 20° C. for 7 days and dried/cured to prepare a test plate.

(Evaluation of dripping property)
In an atmosphere of 25° C., the above-described test plate was vertically set, and 0.7 kg/m ² of a coating film remover was applied thereon. After being left to stand for 4 hours, the sagging retention was visually evaluated according to the following criteria.
◎ (very good): The coating remover remains on the entire coated area, and no dripping of the coating remover is observed ○ (good): The coating remover remains on 80% or more of the area of the coated area △ (slightly bad): The coating remover remains in 50% or more of the area of the coated part, and the coating remover is in the direction of gravity. No dripping is seen × (bad): The paint film remover remains only in less than 50% of the area of the coated part, and a large amount of paint film remover dripping is seen in the direction of gravity.

(Evaluation of peeling performance)
In an atmosphere of 25° C., the above-described test plate was vertically set, and 0.7 kg/m ² of a coating film remover was applied thereon. After being allowed to stand for 4 hours, the coating film on the coated portion of the coating film stripping agent was scraped with a scraper, and whether the coating film could be peeled off was evaluated according to the following criteria. It can be said that those with an evaluation of 3 or higher are suitable for practical use.
5: The entire surface of the coating film of the coating remover applied portion can be easily peeled off 4: The entire surface of the coating film of the coating remover applied portion can be removed 3: The coating of the coating remover applied portion 80% or more of the film can be peeled off 2: 50% or more of the coating film of the coating remover applied part can be peeled off 1: Less than 50% of the coating film of the coating remover applied part can be peeled off

As shown above, containing water (A), N-methylpyrrolidone (B), fatty acid monoester (C), dibasic acid ester (D), and sulfonic acid type solubilizer (E) The paint film remover (Examples 1 to 19) exhibits good workability in terms of liquid transparency and storage stability, and exhibits good dripping property and peeling performance for various paint films. rice field.

On the other hand, the coating film stripping agents (Comparative Examples 1 to 6) using a solubilizer other than a sulfonic acid type caused two-layer separation before 1 minute after stopping stirring in the evaluation of the transparency of the liquid, and In the evaluation of the storage stability, separation of the supernatant liquid occurred before 1 minute had elapsed after stopping the stirring, and thus the workability was inferior to that of the coating stripping agent of the present invention. In addition, these coating film-removing agents were inferior to the coating film-removing agents of the present invention in terms of drip retention and peeling performance with respect to various coating films.

Furthermore, the paint film remover containing no fatty acid monoester (C) (Comparative Example 7) was equivalent to the paint film remover of the present invention in terms of liquid transparency and storage stability. It was inferior to the paint film remover of the present invention in terms of peeling performance against.

Claims (4)

Water (A) 5 to 60% by mass , N-methylpyrrolidone (B) 1 to 50% by mass , fatty acid monoester (C) 1 to 50% by mass , and dibasic acid ester (D) 1 to 60% by mass , a sulfonic acid-type solubilizer (E) in an amount of 1 to 50% by mass , and a thickener (F) . 2. The coating stripping agent according to claim 1 , wherein the sulfonic acid type solubilizer (E) is a sulfonate compound. 3. The coating stripping agent according to claim 1 or 2 , wherein the sulfonic acid type solubilizer (E) is a compound containing no aromatic ring or aromatic heterocycle. The coating stripper according to any one of claims 1 to 3 , which does not contain benzyl alcohol.