JP2022151823A - Low-gloss coating composition - Google Patents

Abstract

To provide a coating composition that causes less emanation of formalin and can form a coating layer having a low-gloss appearance that is stable against any change in thickness and coating environment.SOLUTION: The present invention discloses: an oxidation-curable low-gloss coating composition that contains an oxidation-curable resin produced from dry oil fatty acid, semi-dry oil fatty acid or the like, silica powder, extender powder with an average particle size of 0.1-10 μm, a coloring pigment and a hydrazide compound; and a coating method that includes coating a substrate face with the low-gloss coating composition.SELECTED DRAWING: None

Description

The present invention relates to an oxidatively curable low gloss coating composition.

Paints containing alkyd resin modified with drying oil as a binder are called synthetic resin mixed paints in the paint industry, and are widely used mainly for painting iron and wood because of their excellent workability and finish. there is

It is known that the alkyd resin contained in the synthetic resin-blended paint produces formalin in the course of the curing reaction due to oxidative polymerization during film formation. Although the amount of formalin produced is extremely small, the permissible concentration of formalin indoors specified by the Building Standards Law is becoming stricter year by year, and various measures have been studied to suppress the diffusion of formalin during film formation.

In Patent Document 1, the applicant of the present application proposed a coating composition in which a resin component derived from an unsaturated fatty acid is combined with a compound that adsorbs or decomposes an aldehyde compound and a curing accelerator. Further, Patent Document 2 discloses a coating composition containing an alkyd resin containing hydiene fatty acid as a constituent component and a formalin catcher agent.

There is also literature on synthetic resin formulated paints. For example, Patent Document 3 discloses a coating composition containing a phenol-modified alkyd resin, a urethane-modified alkyd resin and an alkyd resin. Patent Document 3 describes that the described coating composition can provide a coating film having high specular gloss in addition to quick-drying properties, crease resistance and weather resistance.

As described in Patent Literature 3, conventionally, a high-gloss glossy appearance has been preferred in the painting of synthetic resin-blended paints. However, in recent years, there has been an increase in the popularity of paints that form a coating film with a subdued gloss and a calm atmosphere.

Synthetic resin blend paint is suitable for painting iron parts, so it is often painted on iron doors of newly built buildings. Although a particularly elegant appearance is required for painting such conspicuous places, a low-gloss type synthetic resin blend paint whose gloss is adjusted to 30% gloss, 50% gloss or matt is applied smoothly. When applied to an iron surface, even a slight difference in film thickness greatly changes the degree of gloss, and there is a problem that the external appearance is not uniform visually. In addition, there is also a problem that coating and curing in a high-humidity environment increase the glossiness of the coating film, which originally had an appearance in which the glossiness was adjusted.

JP 2004-352764 A JP 2010-235827 A Japanese Patent Application Laid-Open No. 2020-63329

An object of the present invention is to provide a low-gloss coating composition capable of suppressing diffusion of formalin and forming a coating film having a stable low-gloss appearance even when the film thickness and the coating environment fluctuate.

The present inventors have extensively studied a method for stably forming a low-gloss coating film in a paint containing an oxidation-curable resin as a binder component. As a result, by combining silica, filler powder with a specific average particle size, coloring pigment, and hydrazide compound in the oxidative curing resin paint, the diffusion of formalin is suppressed, and the desired coating appearance with reduced gloss can be obtained. In addition, it was found that the increase in gloss is suppressed even if the film thickness and coating environment fluctuate greatly.

That is, the present invention is defined in item 1.
An oxidation-curable low-gloss coating composition containing an oxidation-curable resin, silica powder, an extender powder having an average particle size of 0.1 to 10 μm, a coloring pigment, and a hydrazide compound,
Section 2.
Item 1. The coating composition according to Item 1, wherein the oxidation-curable resin is produced from a drying oil fatty acid and/or a semi-drying oil fatty acid,
Item 3.
3. The coating composition according to Item 1 or 2, wherein the oxidation-curable resin is an alkyd resin;
Section 4.
Item 3. The coating composition according to any one of Items 1 to 3, wherein the average particle size of the silica powder is in the range of 0.5 to 15 μm.
Item 5.
Item 5. The coating composition according to any one of Items 1 to 4, wherein the amount of the silica powder is in the range of 0.5 to 10 parts by mass based on 100 parts by mass of the nonvolatile content of the oxidation-curable resin.
Item 6.
Item 6. The coating composition according to any one of items 1 to 5, wherein the amount of the extender powder is in the range of 10 to 200 parts by mass based on 100 parts by mass of the nonvolatile content of the oxidatively curable resin,
Item 7.
A coating method comprising coating the low-gloss coating composition according to any one of Items 1 to 6 on the substrate surface,
Regarding.

According to the low-gloss paint composition of the present invention, diffusion of formalin is suppressed, and a stable low-gloss coating film can be obtained even if the coating environment fluctuates greatly. The low-gloss coating composition of the present invention suppresses the difference in film thickness that occurs during coating or the change in gloss that occurs in areas where coating is applied, so that uneven gloss is inconspicuous even when the composition is coated on a smooth substrate surface. Furthermore, the low-gloss coating composition of the present invention suppresses the increase in gloss that occurs when coating under high-humidity conditions.

The low-gloss coating composition of the present invention contains an oxidation-curable resin, a silica powder, an extender powder, a coloring pigment, and a hydrazide compound.

<Oxidation curable resin>
In the present invention, the oxidatively curable resin encompasses all oxidatively polymerizable resins from which formalin diffusion occurs. Specifically, it may be a resin that uses a drying oil fatty acid and / or a semi-drying oil fatty acid as a production raw material, and alkyd resin, acrylic-modified alkyd resin, urethane-modified alkyd resin, phenol-modified alkyd resin, fatty acid-modified acrylic resin and these Combination etc. are mentioned.

Examples of the alkyd resin include a resin obtained by esterifying a drying oil fatty acid and/or a semi-drying oil fatty acid, an acid component other than the drying oil fatty acid and/or the semi-drying oil fatty acid, and an alcohol component by a method known per se. be done. Drying oil fatty acids and semi-drying oil fatty acids cannot be strictly distinguished, but usually drying oil fatty acids are unsaturated fatty acids with an iodine value of 130 or more, and semi-drying oil fatty acids have an iodine value of 100 or more and less than 130. It is an unsaturated fatty acid. Non-drying oil fatty acids, on the other hand, are usually fatty acids with an iodine value of less than 100.

Examples of drying oil fatty acids and semi-drying oil fatty acids include unsaturated fatty acids such as oleic acid, linoleic acid, linoleic acid, eleostearic acid, and ricinoleic acid, fish oil fatty acids, dehydrated castor oil fatty acids, safflower oil fatty acids, and linseed oil. Fatty acids, soybean oil fatty acids, sesame oil fatty acids, poppy oil fatty acids, perilla oil fatty acids, hemp seed oil fatty acids, grape kernel oil fatty acids, corn oil fatty acids, tall oil fatty acids, sunflower oil fatty acids, cottonseed oil fatty acids, walnut oil fatty acids, rubber seed oil fatty acids, Hydienoic acid fatty acids, combinations thereof, and the like.

Examples of the acid component include benzoic acid, p-tert-butylbenzoic acid, (anhydrous) phthalic acid, hexahydro (anhydride) phthalic acid, tetrahydro (anhydride) phthalic acid, tetrachloro (anhydride) phthalic acid, hexachloro (anhydride) ) Phthalic acid, tetrabromo(anhydride) phthalic acid, trimellitic acid, “himic acid” [product of Hitachi Chemical Co., Ltd.; “himic acid” is a registered trademark of the company. ], (anhydrous) succinic acid, (anhydrous) maleic acid, fumaric acid, (anhydrous) itaconic acid, adipic acid, sebacic acid or oxalic acid and combinations thereof.

In addition, as acid components, saturated fatty acids such as caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, and stearic acid, and non-drying oil fatty acids such as hydrogenated coconut oil fatty acids, coconut oil fatty acids, and palm oil fatty acids. Can be used together.

Examples of the alcohol component include ethylene glycol, propylene glycol, glycerin, trimethylolethane, trimethylolpropane, neopentyl glycol, 1,6-hexanediol, 1,6-hexanetriol, pentaerythritol, sorbitol and combinations thereof. is mentioned.

Examples of the acrylic-modified alkyd resin include a resin obtained by reacting with an acrylic monomer component containing an acrylic monomer capable of reacting with a hydroxyl group and/or a carboxyl group contained in the alkyd resin. Examples of urethane-modified alkyd resins include resins obtained by reacting hydroxyl groups contained in the alkyd resin with polyisocyanate. Examples of phenol-modified alkyd resins include resins obtained by modifying the above alkyd resins with phenol resins.

Examples of fatty acid-modified acrylic resins include fatty acid-modified acrylic resins, epoxy resins, and epoxy resins, which are obtained by reacting a drying oil fatty acid and/or a semi-drying oil fatty acid as described above with a polymerizable unsaturated monomer containing an epoxy group. A fatty acid-modified acrylic resin obtained by reacting a group-containing acrylic resin with a drying oil fatty acid and/or a semi-drying oil fatty acid, a silicone and fatty acid-modified acrylic resin obtained by further reacting the fatty acid-modified acrylic resin with a silicone compound, and the fatty acid-modified acrylic A fatty acid-modified urethane-modified acrylic resin obtained by further reacting a resin with a compound having an isocyanate group may be used.

In the present invention, the oxidation-curable resin is contained in an amount of 10 to 80 parts by mass, more preferably 20 to 50 parts by mass in terms of nonvolatile content in 100 parts by mass of nonvolatile components in the low-gloss coating composition. is suitable.

In the present specification, the non-volatile content means the residue after removing the volatile components, and the residue may be solid or liquid at room temperature.

For example, a known mass (e.g., 0.3 g) is used as a sample, spread in a pre-weighed aluminum dish, and the sample is heated in an oven at 105 ° C. for 30 minutes. be able to.

<Silica powder>
In the present invention, the silica powder is powdery silica at room temperature, and may be a natural product, a synthetic product, or an organically modified silica modified with a fatty acid or the like. A commercially available product can be used as the silica powder. Examples of commercially available products include the Nipsil series manufactured by Tosoh Silica Corporation, the Silysia series manufactured by Fuji Silysia Chemical Ltd., the Sylophobic series, the Silosphere series manufactured by Mizusawa Chemical Industry Co., Ltd., and the Mizukasil series manufactured by Mizusawa Chemical Industry Co., Ltd.

In the present invention, the silica powder preferably has an average particle size of 0.5 to 15 μm, particularly preferably 1.0 to 10.0 μm. When the average particle size of the silica powder is within this range, the coating workability is good, and the glossiness of the coating film formed can be suppressed. In this specification, the average particle size is the average particle size including not only the particle size of the primary particles but also the particle size of the secondary particles (aggregate), and is the D50 value of the volume-based particle size distribution. The D50 value is the particle size at which the cumulative particle size distribution from the small particle size side is 50% from the volume-based particle size distribution. The measurement method is according to JIS Z 8825 using a laser diffraction scattering method. Microtrac MT3300EXII manufactured by Nikkiso Co., Ltd. can be used as a measuring device using the laser diffraction scattering method.

At that time, as a pretreatment, the sample is dispersed by adding it to a mixed solvent of acetone and isopropyl alcohol and applying ultrasonic waves for 1 minute to adjust the sample concentration to a concentration within a predetermined transmittance range set in the device. The transmittance range is, for example, 0.800-0.930.

In the present invention, the amount of silica powder compounded is preferably in the range of 0.5 to 10 parts by mass, particularly 1 to 5 parts by mass, based on 100 parts by mass of the non-volatile matter of the oxidatively curable resin contained in the coating composition. . When the amount of silica powder is within this range, coating workability is good, gloss of the coating film formed can be suppressed, and a high-class appearance can be obtained.

<Strength powder>
The low gloss coating composition of the present invention contains an extender powder.
Examples of the extender powder include calcium carbonate, barium sulfate, clay, talc, mica, aluminum oxide, aluminum hydroxide, alumina, zinc oxide, and combinations thereof. Among these, it is preferable to use calcium carbonate and/or barium sulfate, particularly calcium carbonate.
In the present invention, the extender powder is preferably a fine powder with a small particle size, and the average particle size is in the range of 0.1 to 10 μm, preferably in the range of 0.2 to 4.0 μm. . By using an extender powder with an average particle size within this range, the glossiness of thick film parts such as spliced parts that occurs when painting over a wide area increases, and the humidity of the coating environment increases. This has the effect of suppressing the phenomenon that film glossiness increases.
The content of the extender powder is preferably in the range of 10 to 200 parts by mass, particularly 30 to 150 parts by mass based on 100 parts by mass of the non-volatile matter of the oxidatively curable resin.

<Coloring pigment>
The low gloss paint composition of the present invention contains a colored pigment.
As the coloring pigment, those known in the paint field can be used without limitation. Examples include white pigments such as titanium dioxide and zinc white; blue pigments such as cyanine blue and indanthrene blue; green pigments such as cyanine green and patina. Pigments; organic red pigments such as azo and quinacridone; red pigments such as red iron oxide; organic yellow pigments such as benzimidazolone, isoindolinone, isoindoline and quinophthalone; yellow pigments such as titanium yellow and yellow lead black pigments such as carbon black, graphite and pine smoke; luster pigments such as aluminum powder, copper powder, nickel powder, titanium oxide-coated mica powder, iron oxide-coated mica powder and luster graphite; These may be used alone or in combination of two or more depending on the desired paint color.

<Hydrazide compound>
The low-gloss coating composition of the present invention contains a hydrazide compound as a formalin catcher. The use of a hydrazide compound has the effect of reducing the amount of formalin emitted from the coating film and providing a stable, low-gloss coating film even when the film thickness and the coating environment fluctuate.

Hydrazide compounds include saturated aliphatic carboxylic acid dihydrazide having 2 to 18 carbon atoms such as oxalic acid dihydrazide, malonic acid dihydrazide, glutaric acid dihydrazide, succinic acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide; monoolefinically unsaturated dicarboxylic acid dihydrazides such as acid dihydrazide, itaconic acid dihydrazide; phthalic acid, terephthalic acid or isophthalic acid dihydrazide, and pyromellitic acid dihydrazide, trihydrazide or tetrahydrazide; nitrilotriacetic acid trihydrazide, citric acid trihydrazide, 1,2,4-benzenetrihydrazide, ethylenediaminetetraacetic acid tetrahydrazide, 1,4,5,8-naphthoic acid tetrahydrazide; carbonate dihydrazide, bissemicarbazide, and combinations thereof.

The blending amount of the hydrazide compound is in the range of 0.05 to 5.0 parts by mass, particularly 0.1 to 3.5 parts by mass, based on 100 parts by mass of the non-volatile content of the oxidation-curable resin contained in the coating composition. Inside is preferred.

<Low gloss paint composition>
The low-gloss coating composition of the present invention contains other components such as a curing catalyst, an organic solvent, a pigment dispersant, an antirust pigment, a thickener, an anti-color separation agent, an antifoaming agent, and other components than the oxidation-curable resin. A modifying resin, a known formalin catcher agent other than a hydrazide compound, and a curing agent can be arbitrarily included.

Among these, the curing catalyst is not particularly limited as long as it promotes oxidative curing, and known catalysts can be used. Specific examples include naphthenates and/or octylates of cobalt, barium, vanadium, manganese, cerium, lead, iron, calcium, zinc, zirconium, cerium, nickel or tin, and combinations thereof.

Examples of the organic solvent include weak solvents.

Weak solvent is a term often used in the field, generally means a solvent with weak dissolving power and is not strictly defined, but in the classification of organic solvents according to the Industrial Safety and Health Law and third-class organic solvents.

Specific examples thereof include gasoline, kerosene, coal tar naphtha (including solvent naphtha), petroleum ether, petroleum naphtha, petroleum benzine, turpentine oil, mineral spirits (mineral thinner, petroleum spirit, white spirit and mineral turpentine). including), and these may be used alone or in combination of two or more.

In addition, organic solvents other than weak solvents, such as n-butane, n-hexane, n-heptane, n-octane, cyclopentane, cyclohexane, n-octane, cyclopentane, cyclohexane, cyclobutane and other aliphatic solvents; toluene, xylene and other aromatic solvents; methyl Ketone solvents such as isobutyl ketone; ether solvents such as n-butyl ether and dioxane; ester solvents such as ethyl acetate, n-butyl acetate, isobutyl acetate, ethylene glycol monomethyl ether acetate, butyl carbitol acetate; methyl ethyl ketone, methyl isobutyl Organic solvents such as ketone solvents such as ketones and diisobutyl ketone can also be used.

<Painting method>
Although the low-gloss coating composition of the present invention can be easily cured at room temperature, it may be forcedly dried or cured by heating, if necessary. Normal temperature refers to a temperature at which temperature manipulation such as forced heating or cooling is not performed, although it varies depending on the atmospheric temperature of the environment where the coating is performed, and is, for example, 5 to 40°C.

Substrates to which the low-gloss coating composition of the present invention is applied include metal substrates such as iron, steel plate, zinc plating, stainless steel, aluminum, and titanium; wood; resin substrates such as plastics; It can also be applied to base materials such as mortar, slate, slate roof tiles, and ceramic building materials. These substrates may be provided with a coating film having a known composition.

The coating of the low-gloss coating composition of the present invention is carried out by known means such as spray coating, roller coating, brush coating, flow coating, etc. after diluting with thinner or the like to a viscosity suitable for coating. The coating amount can be appropriately adjusted, but is generally in the range of 30 to 400 g/m ² , preferably 50 to 250 g/m ² .

In addition, when painting, the low-gloss paint composition may be directly applied to the substrate surface, but after applying the undercoat paint to the substrate surface, the low-gloss paint composition is applied as a topcoat paint. You may

The undercoat paint is preferably appropriately selected from known paints such as a primer paint and an antirust paint according to the type of substrate.

The present invention will be further described below with reference to examples. Here, "parts" and "%" mean "mass parts" and "mass%" respectively.

Examples 1-26 and Comparative Examples 1-4
Low-gloss coating compositions (X-1) to (X-30) were produced with the formulations shown in Table 1 and subjected to the following evaluation tests. The results are also shown in Table 1.

(Note 1) 60% alkyd resin solution: 587 parts of soybean oil fatty acid, 251 parts of phthalic anhydride, 7.5 parts of maleic acid, 195 parts of pentaerythritol, and 29 parts of ethylene glycol were charged in a three-necked flask and heated to 180°C. After heating for 1 hour, the temperature was raised to 230° C., reaction was carried out for 8 hours, and the mixture was diluted with mineral spirits to obtain an oxidatively polymerized alkyd resin solution with a non-volatile content of 60%.
(Note 2) Sancal NA2200: trade name, manufactured by Nitchitsu Co., Ltd., calcium carbonate, average particle size 1.4 μm
(Note 3) Softon 1500: trade name, manufactured by Bihoku Funka Kogyo Co., Ltd., calcium carbonate, average particle size 1.5 μm
(Note 4) μ-powder 3N: trade name, manufactured by Bihoku Funka Kogyo Co., Ltd., calcium carbonate, average particle size 1.6 μm
(Note 5) Sunlight SL700: trade name, manufactured by Takehara Chemical Industry Co., Ltd., calcium carbonate, average particle size 4.5 μm
(Note 6) Sancal NA-800: Product name, manufactured by Nitchitsu Co., Ltd., calcium carbonate, average particle size 7.9 μm
(Note 7) Sancal NA-600: Product name, manufactured by Nitchitsu Co., Ltd., calcium carbonate, average particle size 10.3 μm
(Note 8) Precipitable barium sulfate PS-07: trade name, manufactured by Guangxi Xiangzh, barium sulfate, average particle size 0.7 μm
(Note 9) Silysia 710: trade name, manufactured by Fuji Silysia Chemical Co., Ltd., silica, average particle size 2.4 μm
(Note 10) Silysia 350: trade name, manufactured by Fuji Silysia Chemical Co., Ltd., silica, average particle size 3.7 μm
(Note 11) Silysia 440: trade name, manufactured by Fuji Silysia Chemical Co., Ltd., silica, average particle size 5.9 μm
(Note 12) Silicia 450: trade name, manufactured by Fuji Silysia Chemical Co., Ltd., silica, average particle size 8.0 μm.

<Evaluation test>
(1) Coating Workability The workability when each coating composition obtained in Examples and Comparative Examples was applied with a brush was evaluated according to the following criteria.
⊚: Easy to move the brush and easy to apply ∘: Some force is required to move the brush, but no problem △: The brush is heavy and tends to be rough ×: The brush is very heavy and difficult to apply.

(2) Finishing property Each low-gloss coating composition obtained in Examples and Comparative Examples is applied to a 60 × 90 cm tin plate using a 6 mm long short hair roller so that the dry film thickness is 30 µm, It was dried at 23°C and 50% RH for 7 days to prepare a test coated plate. After measuring the 60° specular gloss (hereinafter referred to as 60°G) of each test coated plate obtained according to JIS K5600-4-7 (1999), the smoothness was visually evaluated according to the following criteria. In addition, although the types of gloss are shown in the table, there is no superiority or inferiority with respect to the types of gloss in the present invention. The 5-minute gloss is about 35±5 at 60°G, and the 3-minute gloss is about 15±5 at 60°G.
(Evaluation criteria for smoothness)
◎: no coating surface roughness is observed ○: coating surface roughness is observed very slightly but not noticeable level △: roughness is clearly observed on the coating surface ×: significant roughness on the entire coating surface Is recognized.

(3) Inhibition of gloss rise (film thickness dependency)
A test coated plate was prepared in the same manner as in the finish quality test except that the dry film thickness was changed from 30 µm to 60 µm, and 60°G was measured.
The difference (Δ60°G (60 μm−30 μm)) between 60° G when the film thickness was 60 μm and 60° G when the film thickness was 30 μm was calculated and evaluated according to the following criteria. It was judged that the smaller the Δ60°G, the better the suppression of the increase in gloss caused by the film thickness change.
◎: Δ60 ° G (60 μm-30 μm) is 0 to 10
○: Δ60°G (60 μm-30 μm) is over 10 and 20 or less △: Δ60°G (60 μm-30 μm) is over 20 and 30 or less ×: Δ60°G (60 μm-30 μm) is over 30 and 40 Less than.

(4) Inhibition of gloss rise (humidity dependence)
In the finish quality test, a test coated plate was prepared in the same manner as in the finish quality test except that the humidity of the coating and drying atmosphere was changed from 50% RH to 80% RH, and 60°G was measured. The difference between 60°G at a humidity of 80% RH and 60°G at a humidity of 50% RH (Δ60°G (80% RH-50% RH)) was calculated and evaluated according to the following criteria. It was judged that the smaller the Δ60°G, the better the suppression of the increase in gloss caused by the change in humidity.
◎: Δ60 ° G (80% RH-50% RH) is 0 to 20
○: Δ60°G (80%RH-50%RH) is over 20 and 30 or less △: Δ60°G (80%RH-50%RH) is over 30 and 40 or less ×: Δ60°G (80% RH-50% RH) exceeds 40.

(5) Amount of formalin emission Each coating composition obtained in Examples and Comparative Examples was subjected to the desiccator method described in JIS-K-5601-4-1 to determine the amount of formaldehyde emission (mg/L), and the following criteria were obtained. evaluated with
○: 0.12 mg/L or less ×: More than 0.12 mg/L

Claims (7)

An oxidation-curable low-gloss coating composition comprising an oxidation-curable resin, silica powder, an extender powder having an average particle size of 0.1 to 10 μm, a coloring pigment, and a hydrazide compound. 2. The coating composition according to claim 1, wherein the oxidation-curable resin is produced from a drying oil fatty acid and/or a semi-drying oil fatty acid. The coating composition according to claim 1 or 2, wherein the oxidation-curable resin is an alkyd resin. The coating composition according to any one of claims 1 to 3, wherein the silica powder has an average particle size in the range of 0.5 to 15 µm. The coating composition according to any one of claims 1 to 4, wherein the amount of silica powder to be blended is in the range of 0.5 to 10 parts by mass based on 100 parts by mass of the non-volatile content of the oxidation-curable resin. The coating composition according to any one of claims 1 to 5, wherein the amount of the extender powder is in the range of 10 to 200 parts by mass based on 100 parts by mass of the non-volatile content of the oxidatively curable resin. A coating method comprising coating a substrate surface with the low-gloss coating composition according to any one of claims 1 to 6.