JP2932620B2 - Method for producing emulsion for water-based paint - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for producing an emulsion for water-based paint, and more particularly, to the water repellency, water resistance, weather resistance,
It has excellent adhesion to inorganic base materials and can be suitably used for both clear paint and enamel paint. Mainly paint for interior and exterior of buildings, paint for steel structure, paint for roof, paint for floor, paint for construction material The present invention relates to a method for producing an emulsion for a water-based paint, which is suitable for the above.

[Prior Art] In recent years, there has been a strong demand for non-polluting paints for environmental protection and safety and health, and conventional solvent-based paints are being converted to aqueous systems. For this reason, applications of the water-based paint have been expanded, and accordingly, the required performance of the water-based paint has been enhanced.

As the coating film performance of the paint, water repellency, water resistance, weather resistance, and adhesion to inorganic substrates, etc. are required, but in conventional water-based paint, none of these properties is excellent. Cannot meet the high performance requirements.

[Problems to be Solved by the Invention] Under the above-mentioned background of the present invention, an emulsion obtained by subjecting an alkoxysilane compound to a condensation reaction in the presence of a specific copolymer latex is used as an aqueous paint. It has been found that when used, the coating film exhibits excellent performance in water repellency, water resistance, composition resistance, and adhesion to an inorganic substrate, and has reached the present invention.

[Means for Solving the Problems] The present invention provides: (a) an alkyl (meth) acrylate monomer having an alkyl group having 1 to 10 carbon atoms of 50 to 99.5% by weight; 0.5 to 15% by weight of a carboxylic acid monomer, and 0 to 49.5% by weight of (c) another monomer copolymerizable with the components (a) and (b) (provided that (a) + (b) + (c ) = 10
Copolymer latex obtained by emulsion polymerization of a monomer comprising
An object of the present invention is to provide a method for producing an emulsion for water-based paint, wherein a condensation reaction of 0.1 to 500 parts by weight of an alkoxysilane compound is allowed to proceed in the presence of 100 parts by weight (in terms of solid content).

 Hereinafter, the present invention will be described in detail.

In the present invention, examples of the alkyl (meth) acrylate monomer having 1 to 10 carbon atoms in the alkyl group, which is the component (a) of the monomer used for producing the copolymer latex used, include: Methyl (meth) acrylate,
Ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate,
N-Amyl (meth) acrylate, i (meth) acrylate
-Amyl, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, i-nonyl (meth) acrylate, decyl (meth) acrylate, hydroxy (meth) acrylate, hydroxyethyl (Meth) acrylate and the like. Among these, n-butyl acrylate, acrylic acid 2
-Ethylhexyl, methyl methacrylate and the like are preferred. These alkyl (meth) acrylate monomers may be used alone or in combination of two or more.

The (a) alkyl (meth) acrylate monomer is an essential component for imparting water resistance, weather resistance and adhesion to the obtained emulsion, and its proportion is 50 to 99.5% of all monomers. % By weight, preferably 70 to 99% by weight, particularly preferably 80 to 98% by weight. If it is less than 50% by weight, it is inferior in water resistance, composition resistance and adhesion, while if it exceeds 99.5% by weight, the stability of the system is exceeded. Is poor, and the adhesiveness is poor.

The (b) ethylenically unsaturated carboxylic acid monomer includes, for example, itaconic acid, (meth) acrylic acid, fumaric acid, maleic acid, crotonic acid and the like, and preferably (meth) acrylic acid. These (b) ethylenically unsaturated carboxylic acid monomers may be used alone or in combination of two or more.
More than one species may be used in combination.

Such (b) ethylenically unsaturated carboxylic acid monomer is
It is an essential component for keeping the balance between polymerization stability and water resistance of the obtained emulsion at a high level, and its use amount is 0.5 to 15% by weight of all monomers, preferably 0.5 to 10% by weight. If the amount is less than 0.5% by weight, the polymerization stability of the obtained emulsion will be reduced and the adhesion will be poor. On the other hand, if it exceeds 15% by weight, water resistance will result.

Further, (c) other monomers copolymerizable with the above components (a) and (b) include, for example, aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene; (meth) acrylamide, N Alkyl amides of ethylenically unsaturated carboxylic acids such as methylol acrylamide; carboxylic acid vinyl esters such as vinyl acetate and vinyl propionate; acid anhydrides, monoalkyl esters, monoamides of ethylenically unsaturated dicarboxylic acids; aminoethyl acrylate; Aminoalkyl esters of ethylenically unsaturated carboxylic acids such as dimethylaminoethyl acrylate and butylaminoethyl acrylate; ethylenically unsaturated carboxylic acids such as aminoethylacrylamide, dimethylaminomethylmethacrylamide and methylaminopropylmethacrylamide Aminoalkyl amides of phosphate;
Vinyl cyanide monomers such as (meth) acrylonitrile and α-chloroacrylonitrile; glycidyl (meth)
Examples thereof include unsaturated aliphatic glycidyl esters such as acrylate and the like, and preferred are styrene, acrylonitrile, α-methylstyrene and the like. These (c) other monomers can be used alone or in combination of two or more.

These (c) other monomers are used in an amount of 0% of all monomers.
449.5% by weight, preferably 0-30% by weight. If it exceeds 49.5% by weight, the film-forming property is reduced, resulting in poor water resistance and adhesion, and problems such as discoloration after film formation and shrinkage of the coating film. Is not preferred.

The copolymer latex of the present invention comprises a specific proportion of the monomers (a) to (c), a known emulsifier, a polymerization initiator,
It is emulsion-polymerized using a chain transfer agent or the like.

Here, as the emulsifier, anionic emulsifiers such as sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium diphenylether disulfonate, succinic acid, sodium dialkylester sulfonate, or polyoxyethylene alkyl ester, polyoxyethylene alkyl ether, etc. One or more types of nonionic emulsifiers can be used. In particular, as an emulsifier that can significantly exhibit the effects of the present invention,
It is sodium alkylbenzene sulfonate.

The amount of the emulsifier to be used is preferably 0.2 to 4% by weight, particularly preferably 0.5 to 3% by weight, based on the total amount of the monomers (a) to (c). If the use ratio of the emulsifier is less than 0.2% by weight, polymerization stability such as formation of a coagulated substance is deteriorated, and there is a problem in production of the copolymer latex, which is not preferable. This is not preferred because the properties and water resistance are reduced.

As a chain transfer agent, α-methylstyrene dimer,
Preferably, α-mailstyrene dimer, terpinolene, α-terpinene, γ-terpinene, dipentene carbon tetrachloride containing 60% by weight or more of a 2,4-diphenyl-4-methyl-1-pentene component, octyl mercaptan, n
-Dodecyl mercaptan, t-dodecyl mercaptan,
n-hexadodecyl mercaptan, diethyl xanthogen disulfide, dimethyl xanthogen disulfide,
Diisopropylxanthogen disulfide, tetraethylthiuram monosulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, dipentamethylenethiuram disulfide, 9,10-dihydroanthracene, 1,4-dihydroanthracene, 1,4-cyclohexadiene, 1,4-cyclo Pentadiene, 2,5-dihydrofuran, xanthene, 3-phenyl-1-pentene and the like can be used, and these are usually used in an amount of 0 to 15% by weight based on the whole monomer.

Further, as the polymerization initiator, potassium persulfate, sodium persulfate, persulfate initiators such as ammonium persulfate, or inorganic initiators such as hydrogen peroxide, cumene hydroperoxide, isopropylbenzene hydroperoxide, para Examples thereof include inorganic peroxides such as menthane hydroperoxide and vesisoyl peroxide, and organic initiators represented by azo-based initiators such as azobisisobutyronitrile. The amount of the polymerization initiator used is preferably 0.03 to 2% by weight, particularly preferably 0.05 to 1% by weight.

In order to promote emulsion polymerization, for example, sodium pyrobisulfite, sodium sulfite, sodium bisulfite, ferrous sulfate, glucose, formaldehyde, sodium sulfoxylate, L-ascorbic acid and salts thereof, reduction of sodium bisulfite Chelating agents such as glycine, alanine and sodium ethylenediaminetetraacetate can be used in combination.

In the emulsion polymerization, in addition to the emulsifier, the chain transfer agent, the polymerization initiator, and the like, various electrolytes, a pH adjuster, and the like are used in combination as needed, and 100 parts by weight of the monomers (a) to (c) are used. On the other hand, using 80 to 300 parts by weight of water and the emulsifier, chain transfer agent, polymerization initiator and the like in an amount within the above range, a polymerization temperature of 10 to 90 ° C, preferably 40 to 80 ° C, and a polymerization time of 6 ~ 40
Emulsion polymerization is carried out under polymerization conditions for a time.

The method of adding the monomers (a) to (c) is not particularly limited, and an arbitrary method such as a batch addition method, a continuous addition method, or a divided addition method is employed.

Incidentally, the final polymerization conversion of the copolymer is 90 to 100%,
In particular, it is preferably 95 to 100%. When seed polymerization is adopted, a polymer obtained by emulsion polymerization of a monomer composed of components (a) to (c) is used as a third particle, and a single particle composed of components (a) to (c) is added thereto. The emulsion polymerization may be performed by adding a monomer mixture.

The copolymer latex in the present invention may be any of the above (a) to
It is obtained by emulsion polymerization of a monomer mixture comprising the component (c) in an aqueous medium. The feature of the present invention is that an alkoxysilane compound is condensed in the presence of a copolymer latex obtained by emulsion polymerization. To make it happen.

When the alkoxysilane compound is represented by the general formula, RnSi
(OR ') _4-n .

In the formula, R is an organic group having 1 to 8 carbon atoms, for example, an alkyl group such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, another γ-chloropyr group, a vinyl group,
3,3,3-trifluoropropyl group, γ-glycidoxypropyl group, γ-mercaptopropyl group, phenyl group, 3,4
-An epoxycyclohexylethyloxy group, a γ-aminopropyl group and the like.

In the formula, R ′ is an alkyl group having 1 to 5 carbon atoms or an acyl group having 1 to 4 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an n-butyl group, and a sec-butyl group. Tert-butyl group, acetyl group and the like.

If the carbon number of R or R 'in the formula is too large, the water solubility becomes low, and the absorbability of the copolymer latex into the copolymer particles becomes poor.

As specific examples of these alkoxysilane compounds,
Tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, i-propyltrimethoxysilane, i-propyltriethoxysilane, γ-chloropropyltrimethoxysilane, γ-chloropropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane,
3,3,3-trifluoropropyltrimethoxysilane, 3,3,3
-Trifluoropropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-mercaptopropyl Trimethoxysilane, γ-mercaptopropyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, γ-aminopropyltrimethoxysilane, 3,4-epoxycyclohexylethyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, Examples thereof include diethyldimethoxysilane. Preferred are tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane and the like. These alkoxysilane compounds can be used alone or in combination of two or more, and can be used in combination with other metal alkoxides such as titanium and aluminum. Further, these alkoxysilane compounds can be used by dissolving in an organic solvent, if necessary.

In the present invention, the condensation reaction of the alkoxysilane compound added to the copolymer latex may be absorbed by the copolymer latex particles or may be performed without being absorbed by the particles. In order to obtain the object of the above, the alkoxysilane compound absorbed and copolymerized by the copolymer particles is preferably at least 5% by weight, more preferably at least 10% by weight of the total alkoxysilane compound used, It is particularly preferably at least 30% by weight.

In the present invention, the method of condensing the alkoxysilane compound added to the copolymer latex can be easily achieved by adding the alkoxysilane compound to the copolymer latex and sufficiently stirring. Further, in order to efficiently absorb the alkoxysilane compound into the copolymer particles, if necessary, a solvent having a solubility in water of ^10-3 % by weight or less is previously absorbed into the copolymer particles of the copolymer latex. It is also possible to put.

Then, the condensation reaction of the alkoxysilane compound added to the copolymer latex (I) is controlled by the reaction temperature and the hydrogen ion concentration.

The reaction temperature in the condensation reaction of the alkoxysilane compound of the present invention is usually 30 ° C. or higher, preferably 50 ° C. or higher, more preferably 70 ° C. or higher, and the hydrogen ion concentration is usually pH 4 to 10, preferably 5 to 5. 9, more preferably 6
８8.

The amount of the alkoxysilane compound added to the copolymer latex (I) is determined by the solid content of the copolymer latex.
0.1 to 500 parts by weight, preferably 0.5 to 100 parts by weight
100 parts by weight, more preferably 1 to 5 parts by weight. If the addition amount of the alkoxysilane compound is less than 0.1 part by weight,
The weather resistance, water repellency and water resistance are poor. On the other hand, if it exceeds 500 parts by weight, not only does the cost rise, but also an improvement effect commensurate with cost cannot be obtained.

The alkoxysilane compound of the copolymer latex may be added during the polymerization step of the copolymer latex (I), preferably at a polymerization conversion of 50% by weight or more.

Incidentally, the solid concentration of the emulsion of the present invention is usually
It is adjusted to 20-70% by weight, preferably 30-60% by weight.
That is, if the solid content concentration of the emulsion is less than 20% by weight, the viscosity of the blend is difficult to adjust in various applications due to the emulsion concentration being too low, and the balance of physical properties tends to decrease. If it exceeds, the viscosity of the emulsion becomes high, and it becomes difficult to disperse the filler and the like.

Fillers such as calcium carbonate, aluminum hydroxide, magnesium hydroxide, clay, barium sulfate, silicic acid, silicate, titanium oxide, magnesium carbonate, calcium carbonate, etc .; Dispersants such as ammonium polyacrylate, sodium hexametaphosphate and potassium pyrophosphate; thickeners such as hydroxyethyl cellulose and high molecular weight sodium polyacrylate; plasticizers such as dioctyl phthalate, dibutyl phthalate and epoxidized fatty acid esters; Auxiliaries such as n-propyl alcohol, ethyl cellosolve, carbitol, ethylene glycol, diethylene glycol; melamine-formalin resin, glyoxal resin, epoxy compound, inorganic metal complex, aziridine compound How curing agent; rosin-modified polyester resins, styrene - may be blended to suit a combination of such leveling agents, such as maleic acid copolymer resin to the purpose of each application.

In addition, the water-based paint emulsion of the present invention may contain an antifoaming agent, a foaming agent, a coloring agent, a flame retardant, a preservative,
An antioxidant, a stabilizer, a vulcanization accelerator, an antistatic agent, a pH adjuster and the like can be added.

[Examples] Hereinafter, the present invention will be described in more detail by way of examples.

Parts and% in Examples are parts by weight and% by weight unless otherwise specified.

Examples 1 to 5 and Comparative Examples 1 to 7 (1) Production of Emulsions A to E and I to Ion exchange in a stainless steel autoclave equipped with a condenser, a nitrogen inlet, a thermometer, and a monomer addition pump stirrer 100 parts of water and sodium peroxide as a polymerization initiator
Charge 0.5 part, replace the gas phase with nitrogen gas between 15 parts, 80
The temperature was raised to ° C.

In a separate container, add 50 parts of ion-exchanged water and ammonium polyoxyethylene alkyl phenyl ether sulfate
1.0 part, sodium alkylbenzenesulfonate 0.5 part and the monomer components shown in Table 1 were mixed and stirred,
A pre-emulsion was made, which was dropped into the flask over 4 hours. During the dropwise addition, the reaction was carried out at 80 ° C. while introducing nitrogen. After dropping, the mixture was further stirred at 85 ° C for 2 hours.
The reaction was terminated by cooling to 25 ° C.

The polymerization addition ratios a to g of the obtained copolymer latex were all 98% or more.

(2) Adjust the pH of the system to 7 while keeping the temperature at 25 ° C.
The alkoxysilane compound shown in 1 was added, and the mixture was vigorously stirred for about 30 minutes. Thereafter, the temperature of the reaction vessel was raised to 60 ° C., and the reaction was carried out for 3 hours.
I got it.

Emulsions A to E belong to the present invention, and emulsions (I to G) do not belong to the present invention.

(3) Formulation of water-based paint A water-based paint was obtained with the following formulation using the above emulsion.

(4) Evaluation method of water-based paint The above water-based paint was brush-coated on a straight plate, dried at room temperature to prepare a test plate, and subjected to a weather resistance test, an adhesion test,
A water resistance test and a water repellency test were performed. Table 1 shows the evaluation results.
Shown in

 In addition, the measurement of various physical properties was performed by the following methods.

Water repellency (contact angle) The contact angle of the coating film was measured using a contact angle measuring device manufactured by Elma Optical Co., Ltd.

Weatherability Sunshine Weather Meter (Suga Test Machine Co., Ltd.)
Dew Cycle WEL-SUN-DC type) (63 ° C)
The gloss retention and yellowing degree after time exposure were investigated.

For the gloss, a 60 ° specular gloss was measured based on JIS K-5400.

The degree of yellowing was measured using an SM color computer (SM-55-1S-3B, Suga Test Instruments Co., Ltd.).

Adhesion According to JIS K-5401, a 100-mm square cross-cut test was performed, and the peeling state was checked with cellophane tape.
Judgment was made based on the number of adhesions in each piece.

Water resistance Judged by the state of the coating film after immersion in distilled water (20 ° C.) for 24 hours.

(Coating film thickness: 500 μm)…: excellent ○: good △: ordinary ×: bad Examples 1 to 5 are examples of water-based coatings using emulsions within the scope of the present invention. A water-based coating intended for the invention has been obtained.

Comparative Example 1 is an example in which the amount of the alkoxysilane used is less than the range of the present invention, and is inferior in water repellency, water resistance, and weather resistance.

Comparative Example 2 is an example in which the amount of the alkoxysilane used exceeds the range of the present invention, in which the adhesion is inferior, and the performance corresponding to the added amount cannot be obtained.

Comparative Example 3 is an example in which the amount of the unsaturated carboxylic acid used is less than the range of the present invention, and the adhesion is inferior.

Comparative Example 4 is an example in which the amount of the unsaturated carboxylic acid used exceeds the range of the present invention, and is inferior in water resistance.

Comparative Example 5 is an example in which the amount of the alkyl (meth) acrylate used is less than the range of the present invention, and is inferior in water resistance, weather resistance, and adhesion.

Comparative Example 6 (1) Production of Emulsion (f) 50 parts of water was charged into a stainless steel container, and 0.3 parts of sodium alkylbenzenesulfonate was added thereto and dissolved. Next, 10 parts of methyltriethoxysilane were added,
Raise the temperature to 60 ° C with sufficient stirring and react for 3 hours.
A polysiloxane emulsion is obtained.

A copolymer latex was prepared in the same manner as in Example 1 (1) except that the amount of ion-exchanged water charged in the autoclave was changed to 50, and after adjusting the pH to 7, the above polysiloxane emulsion was added thereto. And emulsion (f)
I got

(2) Evaluation of water-based paint The same method as in Example 1 was evaluated using the above emulsion (H). The evaluation results are shown in Table 1.

The emulsion of Comparative Example 6 was simply blended with a copolymer latex and a polysiloxane emulsion. Although the type and amount of the polymer component and the polysiloxane of the copolymer latex were the same as those in Example 1,
A water-based paint with the desired performance cannot be obtained.

Comparative Example 7 (1) Production method of emulsion (g) Copolymer latex in the presence of alkoxysilane compound in the same manner as in Example 1 except that the alkoxysilane compound was mixed with the copolymer latex and the monomer component. Was polymerized to obtain an emulsion (g).

(2) Evaluation of water-based paint Using the above emulsion (g), evaluation was made in the same manner as in Example 1. The evaluation results are shown in Table 1.

The emulsion (g) of Comparative Example 7 was a water-based paint having the desired performance despite the fact that the alkoxysilane compound was the same as in Example 1 in the types and amounts of the monomer component and polysiloxane of the copolymer latex. Can not be obtained.

[Effects of the Invention] According to the production method of the present invention, after adding an alkoxysilane compound to a specific copolymer latex, a condensation reaction of the alkoxysilane compound is allowed to proceed, whereby an aqueous solution capable of meeting a high required performance is obtained. A coating emulsion can be easily produced.

That is, when the emulsion obtained by the present invention is used for a water-based paint, excellent water repellency, water resistance, weather resistance,
Adhesion to inorganic base material is obtained, and it can be suitably used for paints for buildings and exteriors, paints for steel structures, paints for roofs, paints for floors, and paints for building materials.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akio Hiraharu 2-11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd. (56) References JP-A-61-9463 (JP, A) JP-A-63-202631 (JP, A) JP-A-63-202630 (JP, A) JP-A-2-261867 (JP, A) JP-A-48-43490 (JP, A) JP-A 64-4241 (JP, A) JP-A-63-186778 (JP, A) JP-A-61-133277 (JP, A) JP-A-57-185357 (JP, A) JP-A-53-16047 (JP, A) (58) Surveyed field (Int.Cl. ⁶ , DB name) C09D 133/02-133/12 C09D 183/10 C08G 77/442 C08L 33/02-33/12 C08L 83/10

Claims (1)

(57) [Claims] (1) 50 to 99.5% by weight of a (meth) acrylic acid alkyl ester monomer having 1 to 10 carbon atoms in an alkyl group, and (b) 0.5 to 15% by weight of an ethylenically unsaturated carboxylic acid monomer. % And (c) 0 to 49.5% by weight of another monomer copolymerizable with the components (a) and (b) (provided that (a) + (b) + (c) =
Copolymer latex obtained by emulsion polymerization of a monomer consisting of 100% by weight)
A method for producing an emulsion for water-based paints, wherein a condensation reaction of 0.1 to 500 parts by weight of an alkoxysilane compound is allowed to proceed in the presence of 100 parts by weight (in terms of solid content).