JP3527539B2 - Method for producing coating composition - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a coating composition. More specifically, the surface of metal such as iron, plastic, wood, concrete, etc. has scratch resistance, transparency,
The present invention relates to a method for producing a coating composition capable of forming a coating film having excellent boiling water resistance, heat resistance, weather resistance, and adhesion.

[0002]

2. Description of the Related Art Conventionally, various coating compositions containing a silicon compound have been investigated for the purpose of improving scratch resistance. For example, as a method using an alkoxysilane hydrolyzate, Japanese Patent Laid-Open Nos. 53-2565 and 56-56 are available.
22365, JP-A-61-166824 and the like. Further, as a coating composition containing organoalkoxysilane and colloidal silica or colloidal alumina as main components, JP-B-52-39691 and JP-B-5
3-5042, JP-A-54-87736, JP-A-55-
94971, JP-A-56-99236, JP-A-59-6.
It is proposed in Japanese Patent No. 8377. Furthermore, coating compositions using an acrylic copolymer containing an alkoxysilyl group are disclosed in JP-A-3-47871 and JP-A-3-3787.
It is proposed in Japanese Patent Laid-Open No. 54278. Furthermore, in order to exert the respective characteristics of both, it has been noted that a composition obtained by mixing the above-mentioned hydrolyzate of alkoxysilane and an acrylic copolymer is used for coating.

[0003]

However, the coating composition comprising the above mixture has room for improvement in the transparency and boiling water resistance of the resulting coating film. An object of the present invention is to form a coating film having good transparency and boiling water resistance on the surface of metals such as iron, plastics, wood, concrete, etc., and further scratch resistance which the composition originally has. sex,
It is intended to provide a coating composition having heat resistance, weather resistance and adhesion.

[0004]

[Means for Solving the Problems] In order to solve the above problems, as a result of extensive studies, it was found that the physical properties of a coating film can be improved by allowing a specific silicate oligomer to coexist during the copolymerization of an acrylic copolymer. Has reached the present invention. That is, the present invention provides the following general formula [I] in an organic solvent.
In the presence of the silicate oligomer represented by, (meth)
Acrylic acid alkyl ester and hydroxyl group-containing (meth) acrylic acid ester are copolymerized , and (meth)
Contains acrylic acid alkyl ester and hydroxyl group
B) To 100 parts by weight of acrylic ester combined
And the proportion of silicate oligomer is 50 to 150 parts by weight.
In characterized by using, in the manufacturing method of Kotin <br/> grayed composition of a homogeneous solution system.

[Chemical 1] (In the formula, n is an integer of 1 to 20, R is hydrogen or a carbon number of 1 to
4 represents an alkyl group or a phenyl group)

The present invention will be described in detail below. The silicate oligomer used in the present invention is not particularly limited as long as it is represented by the following general formula [I].

[Chemical 1] (In the formula, n is an integer of 1 to 20, R is hydrogen or a carbon number of 1 to
4 represents an alkyl group or a phenyl group)

The silicate oligomer can be obtained, for example, by hydrolyzing tetraalkoxysilane or tetraphenoxysilane such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane and tetrabutoxysilane. n can be adjusted by controlling the hydrolysis rate in this case.

The hydrolysis reaction itself can be carried out by a known method. For example, a predetermined amount of water is added to the above tetraalkoxysilane in the presence of an acid catalyst to distill off the alcohol by-produced, usually at room temperature. The reaction is performed at about -100 ° C. The alkoxysilane is hydrolyzed by this reaction, and a liquid silicate oligomer having two or more hydroxyl groups by a condensation reaction (usually an average degree of polymerization of about 2 to 8,
Preferably 3-6) is obtained as a hydrolyzate. The degree of hydrolysis can be appropriately adjusted depending on the amount of water used, but in view of the physical properties of the coating composition or the curing of the coating film, it is usually 40 to 90 in the present invention.
%, Preferably about 60 to 80%. When it is more than the above range, the adhesiveness is lowered, and when it is less than the above range, n is 0.

The tetraalkoxysilicate oligomer thus obtained usually contains about 2 to 10% of a monomer. If this monomer is contained, the storage stability of the coating composition is lacking, the viscosity increases during storage, and it becomes difficult to form a thin film. Therefore, the monomer content should be 1% or less, preferably 0.3% or less. This monomer removal is carried out by flash distillation and vacuum distillation so that

The amount of silicate oligomer used is (meth)
Contains acrylic acid alkyl ester and hydroxyl group
And 50 ) to 150 parts by weight based on 100 parts by weight of acrylic acid ester . If it is less than this, the hardness of the coating film is remarkably lowered, and if it is more than this, the adhesion to the substrate is remarkably lowered. Incidentally, if the acrylic copolymer content is high in the above range, alkali resistance and storage stability are improved, and if the silicate oligomer content is high, hardness, solvent resistance, weather resistance, and adhesion tend to be improved. is there.

The carbon number of the alkyl group of the (meth) acrylic acid alkyl ester used in the present invention is not particularly limited.
Although any of about 20 to 20 can be used, the use of a combination of an alkyl group having 1 to 3 carbon atoms and an alkyl group having 4 or more carbon atoms can balance the physical properties of the coating film. It is preferable in terms. (A) Alkyl group-containing (meth) acrylic acid alkyl esters having 1 to 3 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate and the like. Are used alone or in combination of two or more.

Examples of the (b) alkyl ester of (meth) acrylic acid having 4 or more carbon atoms in the alkyl group include butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, and (meth) acrylate. ) Acrylic acid t
-Butyl, amyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, (meth)
Examples thereof include octyl acrylate, 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, and stearyl (meth) acrylate, which may be used alone or in combination of two or more.

As the hydroxyl group-containing (meth) acrylic acid ester, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate,
Examples include 3-hydroxypropylpropyl (meth) acrylate and 4-hydroxylbutyl (meth) acrylate. If necessary, aromatic monomers such as styrene and vinyltoluene, and vinyl compounds such as vinyl acetate and vinyl propionate are used together.

The copolymerization ratio of the (meth) acrylic acid alkyl ester and the hydroxyl group-containing (meth) acrylic acid ester is 50 for the (meth) acrylic acid alkyl ester.
˜99.5% by weight, preferably 70-97.5% by weight,
Hydroxyl group-containing (meth) acrylic acid ester is 0.
It is 5 to 50% by weight, preferably 2.5 to 30% by weight. In addition, in the (meth) acrylic acid alkyl ester, an alkyl group (meth) acrylic acid alkyl ester (a) having 1 to 3 carbon atoms and an alkyl group (meth) acrylic acid alkyl ester (b) having 4 or more carbon atoms are included. The ratio of (a) / (b) is preferably 2/8 to 8/2, and more preferably 3/7 to 7/3 on a weight basis.

By using the hydroxyl group-containing (meth) acrylic acid ester, the crosslinkability with the silicate oligomer is improved. In addition, when the coating film is cured, it shrinks, internal stress may occur, and problems such as cracks may occur.To avoid this, the glass transition may be caused by the composition ratio of the acrylic copolymer. It is preferable to set the point low. A specific temperature range of a suitable glass transition point is -20 to 60 ° C.

A feature of the present invention is that a (meth) acrylic monomer is co-polymerized in an organic solvent in the presence of the silicate oligomer. As the method of such co-polymerization,
Although not particularly limited, for example, it can be produced by mixing each component and using a usual radical polymerization method. The organic solvent used in the present invention is not particularly limited, and dissolves (meth) acrylic monomers and copolymers and silicate oligomers.
However , a uniform solution system can be used and can be appropriately selected depending on the substrate to be coated or the coating method. Specific examples of usable organic solvents include alcohols such as methanol, ethanol, n-propanol, isopropyl alcohol, n-butanol, and octanol, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol mono. Glycol derivatives such as n-propyl ether and ethylene glycol mono-n-butyl ether; hydrocarbons such as benzene, kerosene, toluene and xylene; esters such as methyl acetate, ethyl acetate, butyl acetate, methyl acetoacetate and ethyl acetoacetate, and acetone. Ketones such as methyl ethyl ketone, methyl isobutyl ketone, and acetylacetone, and ethyl ether, butyl ether, methyl cellosolve, ethyl cellosolve, dioxane, furan, tetrahydo Ethers such as Rofuran like. These organic solvents can be used either individually or in combination.

The amount of the solvent used can be 20 to 200 parts by weight based on 100 parts by weight of the total amount of the (meth) acrylic monomer and the silicate oligomer. This composition ratio can be appropriately selected according to the purpose of use.

As the polymerization catalyst, known radical polymerization catalysts such as azobisisobutyronitrile, benzoyl peroxide, ditertiary butyl peroxide,
Cumene hydroperoxide and the like are used. A suitable temperature for the polymerization is 60 to 150 ° C., and a practical polymerization time is about 6 to 20 hours. The composition of the present invention is
As described above, the organic solvent used at the time of polymerization can be put to practical use as a solvent in the state of being used as it is, but if necessary, it may be used by substituting it with an arbitrary solvent.

Further, it is desirable to use a curing catalyst in the coating composition of the present invention thus obtained. The curing catalyst should be added before use (two-pack type)
It is also possible to store in the state of being added from the beginning (one-pack type). Specific examples of the curing catalyst include hydrochloric acid, nitric acid, phosphoric acid, inorganic acids such as boric acid, acetic acid, formic acid, maleic acid, phthalic acid, benzoic acid, organic acids such as paratoluenesulfonic acid, dibutyltin laurylate, dibutyltin octoate, Dibutyltin acetate, organotin compounds such as dioctyltin laurate, tetrabutyl titanate, tetrapropyl titanate, organotitanium compounds such as tetrabutoxy titanate, monomethyl phosphate, phosphate esters such as monoethyl phosphate, γ
-Aminopropyltrimethoxysilane, N-β-aminoethyl-γ-aminopropyltrimethoxysilane, γ-
There are silane coupling agents such as ureidopropyltriethoxysilane.

In addition, organoaluminum compounds such as tris (acetylacetonato) aluminum and tris (ethylacetoacetate) aluminum, tetrabutylzirconate, organozirconium such as butoxytris (acetylacetonato) zirconium, ethylenediamine, diethylenetriamine, piperazine , Amines such as metaphenylenediamine, diethanolamine and triethanolamine, alkali compounds such as sodium hydroxide and potassium hydroxide, and epoxy compounds.
Inorganic acids, organic tin compounds, organic acids and organic aluminum compounds are particularly preferable. The amount of these catalysts used varies depending on the catalyst, but when hydrochloric acid is used, it is preferably about 0.1 to 2 parts by weight with respect to 100 parts by weight of the silicate oligomer.

The method of using the composition of the present invention will be described more specifically. The co-polymerized (meth) acrylic copolymer composition is usually adjusted in concentration, a curing catalyst is then added, and then the composition is applied to a substrate and dried by heating. When R of the silicate oligomer is an alkyl group or a phenyl group, it may be hydrolyzed if necessary.
In this case, the base material can be applied to iron, stainless steel, aluminum, other metals, alloys, plastics, wood, cement, concrete and the like. Examples of the coating method include brush coating, spin coating, spray coating, depping, roll coating, and gravure printing. The film thickness at this time is 0.1 to 20.
The thickness is preferably 0 μm, more preferably 1 to 100 μm. The composition of the present invention is particularly effective for thickening the coating film, and the conventional one had a high possibility of causing cracks and the like at a thickness exceeding 50 μm, but the present invention made it possible to further thicken the film. When it is thinner than the above range, it is difficult to obtain sufficient scratch resistance, and when it is thicker than the above range, cracks may occur, which is not preferable.

When preparing a coating composition using the composition of the present invention, a dehydrating agent or an alkyl alcohol having 1 to 10 carbon atoms in the alkyl group may be added, if necessary, in consideration of the stability of the coating composition. You can also The dehydrating agent in this case, trimethyl orthoformate, triethyl orthoformate, tripropyl orthoformate, trimethyl orthoacetate, triethyl orthoacetate, tripropyl orthoacetate, trimethyl orthopropionate, triethyl orthopropionate,
Orthocarboxylic acid esters such as trimethyl orthoisopropionate, triethyl orthoisopropionate, trimethyl orthobutyrate, triethyl orthobutyrate, trimethyl orthoisobutyrate, and triethyl orthoisobutyrate are used, and the addition amount thereof is a (meth) acrylic copolymer 0 to 30 parts by weight, preferably 0.
5 to 30 parts by weight, particularly preferably 5 to 25 parts by weight.

Further, as the pigment used in the paint, white pigments such as titanium oxide, calcium carbonate, talc, lithobon, barium sulfate, calcium sulfate, alumina and clay, black pigments such as carbon black and iron black, phthalocyanine blue, Blue pigments such as navy blue and ultramarine blue, yellow pigments such as lake yellow, yellow lead, oak yellow and Hansa yellow, red pigments such as red iron oxide and lake red, orange pigments such as chrome vermilion, green pigments such as phthalocyanine green and chromium oxide. And so on.

Further, other additives for resins can be added to the composition of the present invention as long as the curing of the invention is not impaired. For example, ultraviolet stabilizer, antioxidant, antistatic agent, conductivity imparting agent, scratch resistance imparting agent, compatibilizer, adhesiveness imparting agent, colorant, fluidity improving agent, plasticizer, anti-sagging agent, precipitation Examples include an inhibitor and an antifoaming agent. A sand mill, a disper, a ball mill and the like which are usually used are used for preparing the paint. This paint can be used as a top coat paint for exterior materials such as concrete, mortar buildings, roof tiles, and siding boards, and also as a paint for interiors and floors of buildings, and in particular, it has excellent weather resistance in exterior applications. It can be used as paint.

[0024]

In the present invention, a coating composition which gives a coating film excellent in scratch resistance, transparency, boiling water resistance and storage stability can be obtained.

[0025]

The present invention will be described in more detail based on the following examples and comparative examples, but the invention is not limited to the following examples as long as the gist thereof is not exceeded. The coating film was evaluated by the following methods. (1) Cellotape peeling: In order to evaluate the adhesive strength of the coating film, 11 parallel and 11 horizontal and vertical lines perpendicular to the center of the coating film were drawn at 1 mm intervals until reaching the substrate surface, and 1 in 1 cm ²
I added a grid to make 00 squares. A cellophane adhesive tape (trade name: “Cellotape” made by Nichiban) was strongly adhered on the cross of the grid, and the number of squares without peeling was measured when the tape was rapidly peeled in the direction of 90 degrees.

(2) Pencil hardness: The degree of scratches is determined by JIS K
It was evaluated by a pencil hardness test according to 5400. (3) Boiling water resistance of coating film: The coating film was immersed in hot water of 100 ° C. for 3 hours together with the substrate, and the state of gloss and crack generation of the coating film was visually observed. The case where the coating film was not glossy or cracked was rated as ◯, and the one where slight glossiness was recognized was rated as Δ. (4) Transparency (haze): Measured according to JIS K-7105.

[Preparation of Silicate Oligomer] Silicate Oligomer A 500 equipped with stirrer, reflux condenser and thermometer
Tetramethoxysilane 2 was added to a 3 ml round bottom flask.
After adding 34 g and 74 g of methanol and mixing, 0.0
22.2 g of 5% hydrochloric acid was added, and a hydrolysis reaction was carried out at an internal temperature of 65 ° C. for 2 hours. Next, the condenser was replaced with an extraction tube, the internal temperature was raised to 150 ° C., the mixture was extracted with methanol and further heated at 150 ° C. for 3 hours to condense to obtain a hydrolyzate. The degree of polymerization was 3 to 6 and the hydroxyl group was 10 or more. The amount of monomers in the tetramethoxysilane oligomer was 5%.

Silicate Oligomer B Following the above, the tetramethoxysilane oligomer is boiled with a jacket heated to 100 to 150 ° C., and the vaporized monomer is discharged out of the system together with an inert gas. The amount of monomers in the tetramethoxysilane oligomer thus obtained was 0.2%. Silicate Oligomer C Tetraethoxysilane is used instead of the above tetramethoxysilane, and the amount of monomers in the oligomer is 0.3% or less. Tetraethoxysilane oligomer (degree of polymerization 3 to 6)
Got

Examples 1 to 3 400 parts by weight of methyl methacrylate, 500 parts by weight of n-butyl acrylate, 100 parts by weight of 2-hydroxyethyl methacrylate were placed in a flask equipped with a nitrogen inlet tube, a reflux condenser, a thermometer and a stirrer. Part, silicate oligomer A
-C, 500 parts by weight (in terms of pure content), 420 parts by weight of xylene, 80 parts by weight of isopropyl alcohol, and 2 parts by weight of benzoyl peroxide were charged and heated to 90 ° C to start polymerization. 2 hours after the start of polymerization, xylene 3
Polymerization was continued for 10 hours while adding a solution prepared by dissolving 8 parts by weight of benzoyl peroxide in 0 part by weight. Resin component 7
A co-polymerized product having 4% by weight and a viscosity of 2000 cps (25 ° C.) was obtained. Tg was 0 ° C. 600 parts by weight of xylene was added to the above co-polymerized product to make the resin content 57% by weight. 0.95 g of 1N hydrochloric acid is added to this solution, and the mixture is stirred at 65 ° C. for 30 minutes. Add this solution to a glass plate (70 mm × 150 mm × 0.5 m
m) with an applicator and then at 110 ° C for 30
Heat treatment was performed for a minute. The physical properties of this coating film (100 μ) were evaluated by the methods described above, and the results are shown in Table 1.

Examples 4 to 5 In the composition of the monomers in Example 2, 300 parts by weight of methyl methacrylate, 350 parts by weight of n-butyl acrylate, 150 parts by weight of 2-hydroxyethyl methacrylate and 2 parts of acrylic acid were used. To 200 parts by weight of ethylhexyl (Example 4), 400 parts by weight of methyl methacrylate, 100 parts by weight of n-butyl acrylate, 200 parts by weight of 2-hydroxyethyl methacrylate, 2 parts of acrylic acid
-Change to 150 parts by weight of ethylhexyl and 150 parts by weight of styrene (Example 5). The Tg was 18 ° C. in Example 4 and 44 ° C. in Example 5. The results are shown in Table 1. Examples 6 to 7 In Example 2, the amount of silicate oligomer used was 1
000 parts by weight (Example 6) and 1500 parts by weight (Example 7). The results are shown in Table 1. Example 8 The same operation as in Example 2 was performed except that dibutyltin dilaurate was used instead of hydrochloric acid. The results are shown in Table 1.

Example 9 The same operation as in Example 2 was carried out except that tris (acetylacetate) aluminum was used instead of hydrochloric acid. The results are shown in Table 1. Control Example 1 In Example 2, the use of the silicate oligomer was omitted during the copolymerization, and the silicate oligomer was mixed after the polymerization. The results are also shown in Table 1. The haze was measured immediately after producing the mixture.

[0032]

[Table 1] Oligomer Cellotape Peeling Pencil Hardness Water Resistance Water Resistance Transparency (Haze) Example 1 A 100/100 HB ○ 0.3 〃 2 B 100/100 HB ○ 0.3 〃 3 C 100/100 HB ○ 0. 3 〃 4 B 100/100 H ○ 0.3 〃 5 B 100/100 2H ○ 0.3 〃 6 B 100/100 3H ○ 0.3 〃 7 B 100/100 4H ○ 0.3 〃 8 B 100 / 100 HB ○ 0.3 〃 9 B 100/100 HB ○ 0.3 Comparative Example 1 B 100/100 HB △ 32.3

[0033]

EFFECTS OF THE INVENTION The coating composition of the present invention can form a coating film having high adhesion to each substrate, sufficient hardness, good boiling water resistance and excellent transparency. Further, it is a coating composition which has excellent storage stability and coating performance and is extremely easy to handle.

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-3-255183 (JP, A) JP-A-6-145453 (JP, A) JP-A-60-206802 (JP, A) JP-A-3- 239702 (JP, A) JP 62-116605 (JP, A) JP 53-11951 (JP, A) JP 57-94057 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C09D 1/00-10/00 C09D 101/00-201/10

Claims (4)

(57) [Claims] 1. A copolymer of an alkyl (meth) acrylate and a hydroxyl group-containing (meth) acrylic ester in an organic solvent in the presence of a silicate oligomer represented by the following general formula [I] , and (Meth) acrylic
Acid alkyl ester and hydroxyl group-containing (meth) ac
For 100 parts by weight of the total amount of phosphoric acid ester,
A method for producing a coating composition of a uniform solution type , which comprises using a cation oligomer in a ratio of 50 to 150 parts by weight . [Chemical 1] (In the formula, n is an integer of 1 to 20, R is hydrogen or a carbon number of 1 to
4 represents an alkyl group or a phenyl group) 2. The proportion of alkyl (meth) acrylate in the total amount of 100 parts by weight of alkyl (meth) acrylate and hydroxyl group-containing (meth) acrylate is 50 to 99.5% by weight, and hydroxyl is The ratio of the group-containing (meth) acrylic acid ester is 0.5 to
The process according to claim 1, wherein the 50 wt%. 3. The production method according to claim 1 , wherein tetramethoxysilane partial hydrolyzate is used as the silicate oligomer. 4. The production method according to claim 1 , wherein a tetramethoxysilane partial hydrolyzate having a monomer amount of 1% by weight or less is used as the silicate oligomer.