KR20060078448A - Emulsion binders and waterborne paints which are free of volatile cosolvents and antifreezing agents - Google Patents

Abstract

The present invention relates to a composition and a method for preparing an emulsion resin and a water-based paint that does not require a coarse solvent and a cryoprotectant to which the resin is applied, and is a volatile organic compound (VOCs) that is harmful to a human body in the paint additives during water-based paint preparation and freezing The present invention relates to a composition and a method for preparing an emulsion resin and an aqueous coating material capable of satisfying room temperature and high temperature storage properties, cold repeated tests, adhesion, wash resistance, hiding rate, low temperature crack resistance, and workability without an inhibitor.

Water-based paints, emulsion resins, solvents, cryoprotectants, volatile organic compounds

Description

Emulsion binders and waterborne paints which are free of volatile cosolvents and antifreezing agents}

The present invention relates to a composition and a method for preparing an emulsion resin suitable for interior and exterior coatings for aqueous construction. As the industry develops and housing changes rapidly, the demand for petrochemical products is increasing rapidly. In particular, volatile organic compounds are not only the cause of ozone layer destruction and cancer, but also the cause of sick house syndrome.

Conventional water-based paints have added a large amount of co-solvents and volatile organic compounds such as cryoprotectants to improve stability upon thawing after freezing in winter as an aid to help coat formation.

Korean Patent Registration Publication No. 10-0149696 describes the preparation and coating of an emulsion polymer polymerized with a minimum amount of emulsifier, but this method requires a high amount of volatile co-solvent, although the water resistance of the coating film and the block prevention ability are improved. There was a disadvantage.

US Pat. No. 6,218,455 describes the preparation of ethylene-vinylacetate resins using nonionic water-dispersible polyurethanes and polyoxyethylene-polyalkylene glycols as particle stabilizers and the use of them as binders for aqueous paints. Polyurethane resin has excellent film forming ability at low temperature without block, good block prevention at high temperature, and does not require cryoprotectant when using polyoxyethylene-polyalkylene glycol. Although it can be produced as a coating binder, there is a disadvantage that the price is expensive and the manufacturing process of the resin is complicated.

In US Pat. No. 6,028,139, ethylene-vinylacetate copolymer resin was prepared by using surface-active initiators to increase particle surface energy, and it was shown that it was possible to eliminate the co-solvent and volatile cryoprotectant added when used as an aqueous coating binder. However, the technique has a disadvantage that the price of the initiator is not only expensive than the general purpose water-soluble initiator, but also a low polymerization conversion rate, a lot of unreacted monomers.

U.S. Patent No. 5,969,032 describes a mixture of a reactive emulsifier having an arylamine group at its end in a non-reactive emulsifier to improve the mechanical stability of the resin, the contact angle and the glossiness of the paint. However, this technique has low freeze stability of the emulsion resin and still requires the addition of a cryoprotectant, and the application of a matting agent is required due to its high gloss to be applied to a matte paint.

US Pat. No. 5,610,225 has shown that polymerizable polyethylene glycol monomers can be copolymerized with acrylic monomers to improve freeze stability and can be made into paints without the use of cryoprotectants and co-solvents. However, resins copolymerized using polyethylene glycol monomers have a disadvantage of high price and poor water resistance and wash resistance of the coating film.

In order to solve the above problems, in the present invention, in the polymerization of the shell copolymerized monomers in the presence of the core particles, the shell composition is acrylic monomers and styrene monomers using a reactive emulsifier containing 4 to 30 mol of ethylene oxide units in the molecule. The present invention is completed by copolymerizing with ureido ring (ethylene urea ring) -containing monomers.

When applying the resin synthesized by the technology of the present invention, the water-based paint is a room temperature and high temperature storage, cold and cold repeated experiments, adhesion, wash resistance, hiding rate, even without the solvent and cryoprotectant volatile organic compounds (VOCs) harmful to the human body Low temperature cracking property and workability can be satisfied.

Hereinafter, a more detailed look at the production method of the emulsion polymer prepared by the present invention to solve the above problems are as follows.

In the method for preparing an aqueous coating resin of the present invention, core particles prepared by emulsion polymerization of ethylenically unsaturated monomers capable of radical polymerization are present in an amount of 1 to 50 parts by weight based on 100 parts by weight of the structural monomer of the shell, based on solid content. (1) 100 parts by weight of structural monomers (2) 0.25-10 parts by weight of acid monomers (3) 0.1-5 parts by weight of ureido ring-containing monomers (4) 4 to 30 moles of ethylene oxide units in the molecule By radical polymerization of 0.2-5 parts by weight of the radically polymerizable reactive emulsifier in an aqueous phase using an initiator, a polymer having a glass transition temperature of -5 to -25 ° C of the resulting emulsion polymer was obtained. The above problem can be solved by using a polymer having a specific property.

When the core particle is less than 1 part by weight with respect to 100 parts by weight of the shell structure monomer in the present invention, the reaction stability is lowered. When the core particle exceeds 50 parts by weight, the size of the final particle is reduced and the amount of the required emulsifier is increased, such as the water resistance of the final resin. There is a disadvantage that the physical properties are lowered.

The core is an emulsion polymer, the particle size is 50 ~ 250nm and as the emulsifier can be synthesized by using a reactive emulsifier and a non-reactive emulsifier which can be radical polymerization, respectively or mixed. If the particle size of the core is 50 nm or less, the size of the final synthesized particles is reduced, and the amount of emulsifier required to secure polymerization stability is increased, thereby deteriorating the physical properties of the synthesized resin. There is a disadvantage in that the adhesion to the porous substrate is inferior.

In the present invention, the reaction proceeds in a semi-continuous manner, so that the core may be introduced at the beginning of the reaction, or part of it may be simultaneously introduced together with the monomer mixture of the shell as necessary. In addition, the core uses a general emulsion resin, and the emulsifier used to colloidally stabilize the core particles can be both a reactive emulsifier capable of non-reactive and radical polymerization.

The structural monomers in the shell monomer composition are capable of radical polymerization, for example one or more from styrene, vinyltoluene, methylstyrene, ethylene, butadiene, vinyl acetate, vinyl chloride, vinylidene chloride, acrylonitrile or alkyl (meth) acrylates. Select and use.

Acid monomers are also capable of radical polymerization and contain acid functional groups in the molecule, for example acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, monoalkylmaleate, monoalkylfumalate, monoalkylitaconate Or one or more selected from vinyl benzoic acid. When the content of the acid monomer is less than 0.25 parts by weight, the stability of the prepared paint is lowered. When the amount of the acid monomer is greater than 10 parts by weight, the water resistance of the coating is poor.

The ureido ring-containing monomer is capable of radical polymerization and includes a ureido ring in its molecule. For example, in the background arts and claims of Korean Patent Application Laid-Open Publication No. 2000-0022100 and Korean Patent Application Publication No. 2002-0000627, the preparation and molecular structure thereof are described. Representative monomers include N- (2-methacryloyloxyethyl) ethylene urea, N- (2-methacryloxyacet amido ethyl) -N-arylalkyl ethylene urea, N- (meth Krill amido) ethyl ethylene urea (sigomer WAM2, rhodiasa), N- (allyloyl) -2- (hydroxy propyl) -aminoethyl ethyleneurea (sigomer WAM, rhodiasa) or fumaric acid and hydroxyethyl Diester compounds with ethylene urea (cylink C4, Cytec Co., Ltd.) and the like. Such a ureido ring-containing monomer has a strong polarity of the ureido ring, and may improve stability due to hydrogen bonding with water, etc., thereby preventing the use of a cryoprotectant. If the amount of the ureido ring-containing monomer is less than 0.1 parts by weight, the physical properties such as washing resistance is inferior, if more than 5 parts by weight has a disadvantage of poor polymerization stability.

Reactive emulsifiers usable in the present invention contain 4 to 30 moles of ethylene oxide units in the molecule and have ethylenically unsaturated groups to enable radical polymerization, and may be used alone or in combination with nonionics. Detailed description of the manufacturing method and molecular structure in Japanese Patent Laid-Open No. 62-34947, Japanese Patent Laid-Open No. 49-46291, Japanese Patent Laid-Open No. 58-203960, Japanese Patent Laid-Open No. 4-53802, Japanese Patent Laid-Open No. 62-104802, Japanese Patent Laid-Open 52-134658, etc. Representative emulsifiers include anion-based ammonium salts of nonylpropenylethoxyether sulfate, DKS's Aquaron HS-5 (5 moles of EO), HS-10 (10 moles of EO), and Adekaria from Asahi Denka Kogyo Co., Ltd. Soap SE-10N (10 moles of EO) and the like, and nonionics include Neugen RN-10 (10 moles of EO), which is an aryl polyoxyethylene nonyl phenyl ether system. The reactive emulsifier may have a high polarity due to the intramolecular ethylene oxide group to improve the stability of the resin to water so as not to use a cryoprotectant. If the content of the emulsifier is less than 0.2 parts by weight, the polymerization stability is lowered. If the content of the emulsifier is more than 5 parts by weight, the water resistance of the coating film is poor.

The polymerization initiator usable in the present invention is capable of both water solubility and usefulness used in conventional emulsion polymerization, and may be used alone or in combination with a reducing agent. Such polymerization initiators include, for example, ammonium persulfate, sodium persulfate, potassium persulfate, t-butyl hydroperoxide, 4,4'-azobis (4-cyano valeric acid) as water solubility, 2'-azobisbutyronitrile, 2,2'-azobis-2-methyl butyronitrile, cumene hydroperoxide and the like, and reducing agents include ascorbic acid, sodium formaldehyde sulfoxylate, sodium bisulfite Etc. are preferable. The polymerization initiator may be added before the monomer composition is introduced, or may be used simultaneously with the monomer. Since the type and the amount of the initiator have a large influence on the water resistance of the coating film, it is preferable to select and use within the range of 0.1 to 3.0% by weight of the shell monomer composition to satisfy the water resistance. If the amount of the initiator is too large, the coating film water resistance is poor, if too small, the polymerization conversion rate is low.

The pH during the polymerization reaction is preferably maintained at a pH of 4 or less so as to increase the efficiency of the initiator when the water-soluble initiator is used and not to ionize the acid monomer. In addition, the polymerization temperature has a large effect on the polymerization conversion rate and should be selected within an appropriate range according to the initiator properties.

It is important for the emulsion polymer produced in the present invention to be adjusted between pH 7-9 to ensure particle colloidal stability and shelf life of the paint. The neutralizing agent can be selected from ammonia and volatile amines which can react with the carboxyl group, or can be selected from metal bases, but is preferably volatilized to secure water resistance of the coating film. Specific examples of the neutralizing agent include ammonia and volatile amines. In the present invention, the pH can be adjusted by using a buffer without using a neutralizing agent as necessary. Examples of suitable buffers include sodium bicarbonate and the like.

In the present invention, if necessary, a molecular weight regulator may be used during emulsion polymerization . Examples of the molecular weight modifier include carbon tetrachloride, n-alkyl mercaptan, alkyl mercapto propionic acid and alkyl esters thereof.

The glass transition temperature of the emulsion polymer in the present invention is characterized in that it is between -5 ~ -25 ℃, which serves to facilitate the formation of the coating film without the need for a solvent when preparing the paint. If the glass transition temperature is higher than -5 ℃, cracks occur when forming the coating film at low temperature, and if the glass transition temperature is lower than -25 ℃, the coating film is too soft, so the washing resistance is very poor.

The resin prepared above is coated with white pigment, extender pigment, wetting agent, dispersant, antifoaming agent, thickener, preservative, antiseptic, plasticizer, water and the like. Preferably, these additives are selected as products that do not contain volatile organic compounds. do.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to the following examples.

Example 1

Manufacturing composition and manufacturing process of emulsion resin according to the present invention

TABLE 1 Preparation of Emulsion Resin

After dissolving sodium bicarbonate in deionized water at the compounding amount shown in Table 1, and then putting into a four-necked 5L round flask, and then H5215 as a core material, and then installed a stirrer, nitrogen inlet tube, condenser, thermocouple, dropping tank, respectively. The temperature is raised to 80 ° C while adding nitrogen. Next, the order 4 to 12 in the above table is sequentially weighed in a container and prepared as a preemulsification solution, and then it is added dropwise to a 5L flask using a feed pump for 4 hours and maintained for 1 hour. After cooling and maintaining the temperature at 65 DEG C, the solution dissolved by mixing the order of 13-14 and 15-16 in the table to the content described in the above was added dropwise to the flask and half of the content was added to the flask for 30 minutes at the same time. After that, the remaining amount is dropped for 30 minutes and maintained for 30 minutes. Cooled again to 35 ° C., filtered through a 200 mesh filter and packaged (50.0% solids, 250 nm particle size, pH 7.1, viscosity 85 cPs). The minimum coating film formation temperature of the prepared emulsion resin was 0 ℃ or less and the glass transition temperature measured by DSC was -12.5 ℃.

Comparative Example 1

Synthesis of Emulsion Resin by Non-Reactive Emulsifier

33.3 g / nonylphenol ethoxylate of polyoxyethylene (EO 4 mol) alkylphenol sulfate ammonium salt (Rhodia Co. CO-436, solid content 60%) in place of 39.2 g of DKS Aqualon HS-10 of Example 1 EO-20) was subjected to emulsion polymerization using 19.6 g. The prepared emulsion resin had a solid content of 50.1%, a particle size of 273 nm, a pH of 7.0, a viscosity of 102 cps, a minimum film forming temperature of 0 ° C. and a glass transition temperature of DSC measured at −15.2 ° C.

Comparative Example 2

Synthesis by composition remove ureido ring-containing monomer

Rhodia sipomeric WAM2 of Example 1 was removed in Example 1 and emulsion polymerization was performed. The prepared emulsion resin had a solids content of 49.7%, a particle size of 245 nm, a pH of 7.0, a viscosity of 75 cps, a minimum coating film formation temperature of 0 ° C. and a glass transition temperature of DSC measured at −10.5 ° C.

Comparative Example 3

Emulsified polymer with glass transition temperature higher than the scope of the present invention

In Example 1, methylmethacrylate, styrene, and 2-ethylhexyl acrylate were changed to 531.3 g, 565.9 g, and 897.9 g, respectively. Solid content of the prepared emulsion resin was 50.2%, particle size was 248nm, pH 7.1, viscosity was 90cps, the minimum coating film formation temperature was below 0 ℃ and the glass transition temperature measured by DSC was -0.1 ℃.

[Comparative Example 4]

Emulsified polymer with a glass transition temperature lower than the range of the present invention

In Example 1, the amount of methyl methacrylate, styrene, and 2-ethylhexyl acrylate were changed to 335.4 g, 370.0, and 1289.7 g, respectively. Solid content of the prepared emulsion resin was 59.8%, particle size was 252nm, pH 7.1, the viscosity was 77cps, the minimum coating film formation temperature was below 0 ℃ and the glass transition temperature measured by DSC was -29.5 ℃.

Experimental Example

Preparation of paints according to Examples and Comparative Examples and Evaluation of Paint Properties Tested

Using the examples and comparative examples described in the present invention were sequentially added to the formulation as shown in Table 2 below to meet the KSM6010-2 class 1 regulations to prepare an aqueous building interior paint using a high-speed resolver. At this time, the solid content of the final paint was 53%, the percent pigment volume (PVC) was 65%, the pigment content in the paint was prepared to be 45% by weight, solid content volume ratio of 32%. As a dispersing and wetting agent, polycarboxylic acid type Sanofco's Nopco 44-S, white pigment as titanium dioxide rutile (Kronos Co., Ltd. 2020), sieving pigment as calcium carbonate (Omiya 6) and aluminum silicate (Angel Hard Co., Ltd.) ASP-170), the antifoaming agent is an emulsion-based Sanofcosa Nopco-1407K, the thickener is hydroxy ethyl cellulose (Herculis Natrasol 250HBR), the antibacterial agent is Carbendazim of Vestek, polypropylene glycol and plastic resin emulsion is a plasticizer The products of Examples and Comparative Examples presented in the following were used.

[Table 2] Paint Composition

The paint properties were tested at room temperature and high temperature storage, repeated cold and cold tests, adhesion, wash resistance, and concealment rate according to KSM6010 standard, and low temperature cracking was performed once by brush painting on a slate plate and then left in a 3 ℃ constant temperature and humidity chamber to observe the film formation. It was. Workability was evaluated in consideration of ICI viscosity, rheological propensity, color separation, observation of sag resistance, and subjective judgment of the operator .

[Table 3] Paint and coating property test results

(In Table 3, the viscosity of one week indicates the difference between the viscosity and the concealment rate, which means the contrast ratio between the white and black surfaces, and the wash resistance is when the dry coating is brushed under the same conditions using a brush in water. The number of brush strokes until the appearance)

The paint prepared using the resin synthesized by the composition and method of the present invention as described above has excellent thermal stability and freezing stability, and has good washing resistance, adhesion and low temperature cracking without using volatile coarse solvent and cryoprotectant which are harmful to human body. Did not occur.

As described above, the emulsion resin prepared according to the method of the present invention is a coating material at room temperature and high temperature storage, cold repeated experiments, adhesion without the solvent and cryoprotectant of volatile organic compounds (VOCs) harmful to the human body in the paint additives during the production of water-based paints It can satisfies the resistance, wash resistance, hiding rate, low temperature crack resistance and workability.

Claims (7)

1 to 50 parts by weight of core particles, 100 parts by weight of structural monomers, 0.25 to 10 parts by weight of acid monomers, and a ureido ring (ethylene urea ring) -containing monomer, 0.1 to 50 parts by weight, based on the solid content prepared by emulsion polymerization of the ethylenically unsaturated monomers capable of radical polymerization. ˜5 parts by weight, 0.2-5 parts by weight of a radically polymerizable reactive emulsifier containing 4-30 moles of ethylene oxide units in the molecule, is prepared by polymerizing in the presence of 0.1-3% by weight of a radical initiator based on the total monomers in the water phase. Core-shell emulsion polymer, characterized in that. The method of claim 1, The glass transition temperature of the emulsion polymer is a core-shell emulsion polymer, characterized in that -5 ~ -25 ℃. The method of claim 1, The structural monomers are capable of radical polymerization, and may be selected from at least one of styrene, vinyltoluene, methylstyrene, ethylene, butadiene, vinyl acetate, vinyl chloride, vinylidene chloride, acrylonitrile or alkyl (meth) acrylate. Emulsified polymer. The method of claim 1, The acid monomers are capable of radical polymerization and include acid functional groups in the molecule, such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, monoalkylmaleate, monoalkylfumalate, monoalkylitaconate or vinylbenzoic acid. Emulsified polymer, characterized in that used by selecting one or more from. The method of claim 1, The ureido ring-containing monomer is capable of radical polymerization and includes a ureido ring in its molecule, and includes N- (2-methacryloyloxyethyl) ethylene urea and N- (2-methacryloxyacet amidoethyl)- N-arylalkyl ethylene urea, N- (methacryl amido) ethyl ethylene urea, N- (allyloyl) -2- (hydroxy propyl) -aminoethyl ethyleneurea or di-fumaric acid with hydroxyethyl ethyleneurea Emulsified polymer, characterized by using at least one selected from ester compounds. The method of claim 1, The reactive emulsifier is an emulsion polymer, characterized in that any one or more selected from nonylpropenylethoxyether sulfate ammonium salt, allyl polyoxyethylene nonylphenyl ether and the like. An aqueous building paint prepared using the emulsion polymer according to any one of claims 1 to 6.