KR20060078972A - Preparing method for water dispersable polyurethane resin containing inorganic compounds and aqueous coating composition containing said water dispersable polyurethane resin - Google Patents

Abstract

The present invention relates to a method for producing a polyurethane water-dispersion resin containing an inorganic substance, a polyurethane water-dispersion resin prepared according to the invention, and an aqueous coating composition for automobiles containing the same. Resin prepared according to the production method of the present invention additionally expresses the intrinsic properties of the inorganic particles while maintaining the excellent physical properties of the conventional urethane dispersion resin, in particular not only excellent dryness, water resistance, chipping resistance, etc. In addition, the VOC discharge and the drying property at low temperatures, which are the biggest disadvantages of the water-based coating composition for automobiles to which the automotive coating composition is applied, have the advantage of being able to wet-on-wet coating in system coating.

Inorganic Resin, Urethane, Water Dispersible Resin, Automobile, Water-based Paint, Wet-on-Wet

Description

Preparation method for water-dispersable polyurethane resin containing inorganic compounds and aqueous coating composition containing said water dispersable polyurethane resin

The present invention relates to a method for producing a polyurethane water-dispersion resin containing inorganic particles therein, to a polyurethane water-dispersion resin prepared according to the present invention, and to a water-based coating composition for automobiles containing the water-dispersion resin. Method for producing a urethane water dispersion resin that maximizes the dryness of the wet-on-wet dry coating while additionally expressing the intrinsic properties of the inorganic material while maintaining the excellent properties of the conventional water-based urethane dispersion resin, accordingly The present invention relates to a manufactured urethane water-dispersible resin and an aqueous coating composition for automobiles containing the same.

In recent years, nanotechnology has emerged as a messenger of the life revolution, and as a result, the transition from existing products to products with nanotechnology is now active, improving the quality of the entire human industry, including electronics, aviation, biotechnology, energy, and household goods. In other words, high performance, new material creation and efficiency are maximizing. Just a few years ago, even in materials that required high-unit technology for organic and inorganic combinations, nanoparticles have been developed through the development of nanotechnology, making it possible to apply high-functional materials. It has reached a stage that can compensate for the disadvantages that were impossible.

In addition, the standards of volatile organic compounds (VOC) in accordance with environmental regulations are being strengthened around the world, and countries are developing and developing water-based paints that have been water-based in existing solvent-based paints. We established an exclusive factory for water paint to actively respond to environmental regulations. In particular, the desolvation movement in the West is faster than in other regions. In Europe, the base coat was reported to have exceeded 50% in 1999. In addition, it is true that development is under way to achieve visible effects such as energy saving, production equipment and operation cost reduction, and labor cost reduction.

In the case of water-based paints, unlike solvent-based paints, most of the volatile components of the paints are made of water, and thus the drying of the volatiles is delayed, resulting in sagging when forming the coating film, staining and color separation. In addition, in the painting process, the cost increases due to repeated hardening, which makes it necessary to improve the price competitiveness, and to compensate for these problems, the curing process is reduced, the drying property is excellent, and it does not include VOC released from the existing useful type. The manufacturing method of the urethane resin which can perform moderately dry coating of water soluble type was developed.                         

U.S. Patent No. 6,610,779 for preparing and characterizing urethanes for aqueous base coats and their properties; 6,620,511 and 6,579,928 and the like. The urethane dispersion resins described in the US patent have the advantage of being a solid type having a solid content of 30% or more and releasing VOC. However, some of them are high temperature sintering and poor gloss and linearity when forming a coating film. There is this.

This high temperature baking type is converse to the cost increase and the simplification of the process. The industry has overcome the disadvantages of the hardening type by developing a non-hardening type coating by lowering the curing temperature or improving the dryness by continuously developing new paints. However, in order to satisfy the physical properties of the coating film, it is in an inadequate state due to the limitation of lowering the temperature, and in order to improve the drying property, a solvent having a low volatilization temperature and a high volatility is added.

This method remains a problem that must be overcome by deviating from the original purpose of eco-friendly paint.

The present inventors conducted a study to solve the above problems, as a result, the polyurethane water-dispersion resin prepared in accordance with the present invention expresses the inherent physical properties of the inorganic material while maintaining the excellent physical properties of the conventional polyurethane water-dispersion resin The composition was found to be excellent and the present invention was completed.

Automotive water-based paints containing a polyurethane water-dispersion resin prepared according to the method of the present invention improved the economics by reducing the amount of VOC emissions and shortening the curing process compared to the conventional curing type and increased the drying properties at low temperatures, which is a disadvantage .

Accordingly, one object of the present invention is to provide a method for producing a polyurethane water-dispersible resin containing an inorganic material having excellent dryness and excellent water resistance, chipping resistance and the like.

Another object of the present invention is to provide a polyurethane water dispersion resin prepared according to the method of the present invention.

Still another object of the present invention is to provide a water-based coating composition for automobiles containing the polyurethane water dispersion resin prepared according to the present invention.

Method for producing a polyurethane water dispersion resin of the present invention for achieving the above object

(a) 15 to 30% by weight of polyol, 5 to 15% by weight of isocyanate, 0.5 to 5% by weight of compound having two or more hydroxyl groups and one or more carboxyl groups, and 15 to 30% by weight of non-reactive organic solvent And reacting 0.5 to 5 wt% of the nano atomized hydrophobic inorganic material to prepare a polyurethane prepolymer;

(b) 1 to 5% by weight of trivalent amine is added to the obtained polyurethane prepolymer to 100% by weight of the total resin to neutralize the prepolymer, and then 30 to 50% by weight of water is added to prepare a polyurethane water dispersion resin. Doing; And

(c) adding a chain extender of 0.5 to 1% by weight relative to 100% by weight of the total resin to react the unreacted isocyanate present in the water-dispersible resin.

Hereinafter, the present invention will be described in more detail.

(1) Manufacturing method of polyurethane water dispersion resin

The first step of the method for producing a polyurethane water dispersion resin according to the present invention is to prepare a polyurethane prepolymer by reacting a polyol and an isocyanate with a compound having at least two hydroxyl groups and at least one carboxyl group. At this time, the nano-atomized inorganic particles are added to the polyol and the isocyanate to provide a polyurethane prepolymer composed of isocyanate at the end. The reaction is proceeded by completely dissolving the polyol at the beginning of the reaction and then adding the isocyanate.

In the production method of the present invention, a polyol may be used by mixing at least one selected from a polyether polyol, a polyester polyol, a polycarbonate polyol, and a polycaprolactone polyol. Preferably, polyether and polyester diol are used. Good to do. Preferred among these are polyester diols. Polyester polyol has the advantage of excellent flexibility compared to polyether polyol, the chipping property when forming a coating film and the design width is wide, but causes yellowing of the coating film at a high temperature. These hydroxyl values are 53-59 mgKOH / g, and a number average molecular weight is 500-2000. If the hydroxyl value is out of the range of 53 ~ 59mgKOH / g, there is a disadvantage in that the stability and water resistance of the water dispersion phase is weak, and if the number average molecular weight is out of the range of 500 ~ 2000 there is a disadvantage of water resistance and crack generation of the paint dry coating. The usage-amount of these polyols is 15-30 weight% with respect to 100 weight% of polyurethane water dispersion resins. If the amount of use is less than 15% by weight, the water resistance decreases, and if the amount is more than 30% by weight, there is a disadvantage in that the resin synthesis stability is poor.

Isocyanates used in the production process of the present invention are optionally substituted aromatic diisocyanates, optionally substituted cycloalkane diisocyanates, optionally aryl- or cycloalkyl-substituted alkane diisocyanates, for example toluene diisocyanate, 4, One or more selected from 4'-hexaphenyl phenyl methane diisocyanate, 4,4'-dicyclo hexyl methane diisocyanate, 1,6-hexa methylene diisocyanate and isophorone diisocyanate may be used alone or in combination. It is preferable that the usage-amount of these isocyanates is 5-15 weight%. If the amount is less than 5% by weight solvent resistance and chemical resistance is reduced, if the amount exceeds 15% by weight swelling (solving) to the solvent during the coating film formation (film) is not well formed.

In the present invention, a compound having two or more hydroxyl groups and one or more carboxyl groups was used as the anionic group because the carboxyl group has good moisture resistance and excellent dispersibility compared to the sulfone group. Examples of the compound having two or more hydroxyl groups and one or more carboxyl groups include dialkylol carboxylic acids such as dimethylol propionic acid (DMPA) and dimethylol One or more selected from butanoic acid (DMBA) may be used. They are prepared using polycarbonate diols having a terminal hydroxyl group and having at least one carboxyl group. The amount of the compound having two or more hydroxyl groups and one or more carboxyl groups is preferably 0.5 to 5% by weight. If the amount of use is less than 0.5% by weight, the adhesion decreases, and if it exceeds 5% by weight, the water resistance is rather reduced.

Non-reactive organic solvents are cellosolves, pyrrolidones, alcohols such as ethyl cellosulf, butyl cellosulf, hexyl cellosulf, N-methyl-2-pyrrolidone, N-propyl alcohol, isopropyl alcohol, n -One or more types selected from butanol and butyl carbitol can be used alone or in combination, and the amount thereof is preferably 15 to 30% by weight based on 100% by weight of the total resin. If these amounts are less than 15% by weight, the dissolution of the compound having two or more hydroxyl groups and one or more carboxyl groups is poor, and if the amount is more than 30% by weight, the drying property of the coating film of the applied paint is poor.

The atomized inorganics used in the preparation process of the present invention are hydrophobic and can be metal oxides, divalent metals or trivalent metals such as magnesium, copper, fluorine, zinc, selenium, manganese, molybdenum, cobalt, chromium, ZnO ₂ , TiO ₂ , One or two or more selected from Ag and Al can be used in combination. These inorganic materials are located inside the urethane particles because the hydrophilic part is in contact with water and the hydrophobic part of the urethane organic material is hydrophobic in the process of dispersing the hydrophilic urethane organic material containing water. At this time, the amount is 0.5 ~ 5% by weight, the particle size is 10 ~ 50nm. If the particle size is less than 10nm, the hydrophobicity is strengthened, and the drying effect is reduced. If the particle size is larger than 50nm, the dispersion of the dispersion in the urethane particles is deteriorated or the sedimentation is caused by gravity. The inorganic material-containing urethane particles are formed in such a way that the moisture content is reduced compared to the particles formed only of the urethane organic material when forming the coating film, so that the water discharge amount is reduced and the drainage force is improved by the hydrophobicity, thereby improving the dryness. Therefore, if these amounts are less than 0.5% by weight, the water resistance is reduced, and when used in excess of 5% by weight has a disadvantage in that the aqueous dispersion stability is poor.

The reaction of the first step can be promoted using a reaction accelerator, for example dibutyltin dilaurate.

The second step of the method for producing a polyurethane water dispersion resin according to the present invention is to neutralize the anionic polyurethane prepolymer prepared in step 1 by adding a trivalent amine and to add water to prepare a water dispersion resin.

Alkyl-substituted amines or alkanol amines such as triethyl amine or dimethylethanol amine can be used as the trivalent amine, and the amount of the trivalent amine is preferably 1 to 5% by weight based on 100% by weight of the total resin. If the amount is less than 1% by weight, the stability of the water in the resinous phase of the water dispersion is lowered, and if it is outside the 5% by weight, there is a disadvantage that the pH is increased. In addition, the degree of neutralization is preferably 80 to 100% with respect to the acid equivalent number present in the prepolymer.

After neutralization with trivalent amine, water is added while the water is added to the resin. In this case, it is preferable to allow the aqueous dispersion to proceed at a temperature of 30 to 40 ° C. for stability of the reaction with the isocyanate. Distilled water is preferably used for the preparation, and is used in an amount of 30 to 50% by weight. If the amount is less than 30% by weight, water dispersion stability is inhibited, and if the amount is more than 50% by weight, the coating film drying property is poor.

The third step of the method for producing a polyurethane water dispersion resin according to the present invention is to add a chain long chain to react the unreacted isocyanate.

As the chain extender, monovalent or divalent diamine having at least two or more reactors may be used, and the amount thereof may vary depending on the unreacted isocyanate equivalent ratio. Preferably, the amount of the chain extender is 0.5 to 1% by weight based on 100% by weight of the total resin. Such monovalent or divalent diamines are mono-, di- or tri-amines, eg isophorone diamines, substituted by mono-, di- or tri-alkyl, -alkylene or alkyl-substituted cycloalkylenes. At least one amine type selected from hydrazine, including hydrate form, ethylene diamine, diethylene diamine, diethylene triamine, triethylamine, hexamethylene diamine can be used. On the other hand, the reaction temperature at the time of the chain extension is preferably carried out at 80 ℃, preferably 60 ℃ or less.

The polyurethane water dispersion resin prepared according to the method of the present invention has a pH of 7.0 to 9.5 in order to have water dispersion stability, and the polyol contains an inorganic substance in the water dispersed particles.

As mentioned above, the polyurethane resin prepared according to the present invention not only improves the drying property to express the inherent physical properties of the inorganic material contained while maintaining the excellent physical properties of the conventional urethane resin and to allow wet-on-wet drying. As well as excellent water and chipping resistance. The water-based coating composition for automobiles containing the same minimizes the VOC emissions, which is the biggest disadvantage of the existing paint, improves the drying speed and shortens the curing process, thereby improving economic efficiency.

(2) Automotive Water-Based Coating Composition

The present invention is also 30 to 60% by weight of polyurethane water dispersion resin, 20 to 30% by weight of water, 10 to 20% by weight of solvent, 10 to 20% by weight of white pigment, 5 to 10% by weight pigment, prepared according to the above method It relates to a water-based coating composition for automobiles containing%, 0.1 to 1.0% by weight antifoam, 0.1 to 3.0% by weight thickener, 0.1 to 3.0% by weight curing agent and 0.1 to 1.0% by weight pH adjuster.

The polyurethane water dispersion resin used in the coating composition of the present invention is an aqueous coating binder resin, and the specific composition and its manufacturing method are as described above. It is preferable that the usage-amount of the said polyurethane water dispersion resin is 30 to 60 weight% with respect to 100 weight% of all the coating compositions. If the amount of use is less than 30% by weight, wetting is reduced, and if the amount is more than 60% by weight, there is a problem in that cracking occurs in forming a coating film.

The water used in the coating composition of the present invention is preferably used in an amount of 20 to 30% by weight based on 100% by weight of the total coating composition. Solvents also include cellosolves, pyrrolidones, alcohols such as ethyl cellosulf, butyl cellosulf, hexyl cellosulf, N-methyl-2-pyrrolidone, N-propyl alcohol, isopropyl alcohol, n-butanol, One or more types selected from butyl carbitol can be used alone or in combination, and the amount of use thereof is preferably 10 to 20% by weight based on 100% by weight of the total coating composition. If the amount of water used is less than 20% by weight, the storage property is inhibited by swelling by the solvent, and if the amount is more than 30% by weight, the paint viscosity is lowered. If it exceeds, there is a disadvantage of impairing storage stability.

On the other hand, the white pigment of the coating composition according to the present invention can be used a conventional pigment that can be used in the coating composition, preferably it is preferable to use TiO ₂ , the amount of use is 10 to 100% by weight of the total coating composition It is good that it is 20 weight%. In addition, barium sulfate or silica may be used as the extender pigment, and the amount thereof is preferably used in an amount of 5 to 10% by weight based on 100% by weight of the total coating composition. If the amount of the white pigment is less than 10% by weight, the hiding power of the coating is low. If the amount of the pigment is more than 20%, the wettability and adhesion are poor, and if the amount of the extender pigment is less than 5% by weight, the hardness of the coating is poor. When the content exceeds 10% by weight, the flexibility of the coating film is deteriorated.

The antifoaming agent of the coating composition according to the present invention may be used at least one selected from fluorine-modified siloxane, polysiloxane emulsion, and organic-modified siloxane, and preferably organic-modified siloxane may be used. It is preferable that the usage-amount is 0.1 to 1.0 weight% with respect to 100 weight% of all the coating compositions. If the amount of use is less than 0.1% by weight, the defoaming is low, and if it exceeds 1.0% by weight, cratering occurs.

As the thickener, one or more selected from acrylic thickeners and urethane thickeners, fused silica, cellulose thickeners and bentonic thickeners may be used alone or in combination, preferably acrylics. It is preferable that the usage-amount is 0.1 to 3.0 weight% with respect to 100 weight% of all the coating compositions. If the amount is less than 0.1% by weight, the thickening effect is lowered. If the amount is more than 3.0%, the wettability with the pigment is lowered.

As a hardening | curing agent, 1 or more types chosen from a melamine type hardening | curing agent and an acryl type hardening | curing agent can be used individually or in mixture, It is preferable to use a melamine type. The usage-amount is 0.1 to 3.0% with respect to 100 weight% of total coating compositions. If the amount used is less than 0.1% by weight, curing is poor, and if it is more than 3.0% by weight, there is a disadvantage of poor water resistance due to uncured monomer.

The pH adjusting agent may be an alkanol or an amine, and preferably, diethanol amine or the like may be used in an amount of 0.1 to 1.0% by weight. If the amount is less than 0.1% by weight, the neutralization efficiency is low, and if the amount is more than 1.0% by weight, there is a disadvantage in that the storage performance is poor.

In addition to the above components, the water-based coating composition of the present invention may be used by further adding other additives selected from antioxidants, antisettling agents, and rheology control agents as necessary.

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 thereto.

Examples 1-3 and Comparative Examples 1-3

According to the component composition (unit: wt%) shown in Table 1 below, the urethane water dispersion resin was prepared, respectively.

2000 ml 4-neck plaques equipped with stirrer, reflux cooler, nitrogen inlet, thermometer, U 1410 (Unionized, polyester diol, number average molecular weight 2,000), hexamethylene diisocyanate (HMDI) (Bayer's diisocyanate), iso Poron diisocyanate (IPDI) (Bayer, Isocyanate), DMBA (dimethylol butanoic acid), N-methylpyrrolidone (NMP), DBTDL (dibutyltin dilaurate, reaction promoter), zinc oxide The reaction is carried out at 90 ° C. for 3 hours in an atmosphere. When the NCO% is measured and within 3.5%, the reaction is cooled to room temperature and neutralized by adding TEA (triethylamine). After about 30 minutes, distilled water is added to obtain a polyurethane prepolymer dispersion with NCO end groups. Chain extension is performed by adding HH (hydrazine hydrate) of the same stoichiometry as the remaining chain-terminated NCO and stirring at room temperature for 2 hours.

On the other hand, the physical properties of the urethane water dispersion obtained therefrom was measured as follows and the results are shown in Table 2 below.

1) Water resistance: The glass plate is washed with alcohol and toluene mixture sufficiently and dried before use. Prepare a film with a thickness of 100㎛ on the glass plate, and after complete drying, drop 1ml of water to observe absorption and appearance.

2) Pencil Hardness: Mitsubishi UNI pencil is used. The film was prepared on the glass plate with a thickness of 100 μm and the pencil hardness was measured when the surface was scratched and the coating film was completely dried.

From the results in Table 2, it can be seen that the urethane polymer according to the present invention is superior to the conventional urethane water dispersion resin in physical properties such as water resistance and pencil hardness.

Examples 4-6 and Comparative Examples 4-6

Using the resins prepared in Examples 1 to 3 and Comparative Examples 1 to 3, the paint was prepared according to the component composition (unit: wt%) shown in Table 3 below.

On the other hand, the physical properties of the paints prepared therefrom were measured as follows, and the results are shown in Table 4 below.

1) Ford cup: A type of viscosity cup that fills a cylindrical container with a certain volume of paint and measures the time it takes for all the paint to flow out of the hole at the bottom.                     

2) Coating film thickness: The coating thickness of the silicone-acryl-urethane containing coating composition of this invention makes 12-15 micrometers into a prescription coating film.

3) Clear coating film: The coating composition of the present invention is a subsequent coating, which gives the coating film an appearance such as gloss and chemical and physical durability. The prescribed coating thickness is 30-35 micrometers.

4) Appearance: Measure color clarity, gloss and leveling of coating film by QMS, automobile exterior measuring device manufactured by Perceptron, USA. Color clarity is the physical value of fine surface irregularities, planar smoothness, transparency of surface layers such as lacquer, and gloss is a sensory measure (gloss).

5) Weatherability: After leaving 720 hours in W-O-M, an accelerated test device, gloss, color difference, and adhesion are measured.

6) Acid resistance: Measures the occurrence of gloss loss, smearing, and discoloration after spot test with 5% sulfuric acid solution.

7) Moisture resistance: After 72 hours test at a temperature of 50 ℃ and a humidity of 98%, the degree of softening and blister generation is measured.

8) Solvent resistance: Put a cotton cloth with xylene. Scrape 5 times with a fingernail (2Kg force) every minute to measure the condition of the film.

9) Heat resistance: After leaving for 360 hours in 70 ℃ oven, measure the degree of breakage and bubble trace of the film during peeling.

As can be seen from the above results, it can be seen that the urethane water-dispersion resin according to the present invention has a faster drying speed and a higher water resistance than the conventional urethane water-dispersion resin. In addition, when the urethane polymer resin of the present invention is applied to a water-based paint for automobiles, it can be seen that the water-soluble can reduce the VOC emissions, reduce the number of drying process of the coating film and improved water resistance.

Claims (6)

(a) 15 to 30% by weight of polyol, 5 to 15% by weight of isocyanate, 0.5 to 5% by weight of compound having two or more hydroxyl groups and one or more carboxyl groups, and 15 to 30% by weight of non-reactive organic solvent And reacting 0.5 to 5 wt% of the nano atomized hydrophobic inorganic material to prepare a polyurethane prepolymer; (b) 1 to 5% by weight of trivalent amine is added to the obtained polyurethane prepolymer to 100% by weight of the total resin to neutralize the prepolymer, and then 30 to 50% by weight of water is added to prepare a polyurethane water dispersion resin. Doing; And (c) adding a chain extender of 0.5 to 1% by weight relative to 100% by weight of the total resin in order to react the unreacted isocyanate present in the water-dispersible resin; Method for producing a dispersion resin. The method according to claim 1, wherein the polyol is at least one selected from polyether polyol, polyester polyol, polycarbonate polyol and polycaprolactone polyol, and has a hydroxyl value of 53 to 59 mgKOH / g and a number average molecular weight of 500 to 2000. How to. The method of claim 1, wherein the compound having at least two hydroxyl groups and at least one carboxyl group is at least one selected from dimethylol propionic acid and dimethylol butanoic acid. The method of claim 1, wherein the nano atomized hydrophobic inorganic material is magnesium, copper, fluorine, zinc, selenium, manganese, molybdenum, cobalt, chromium, ZnO ₂ , TiO ₂ , At least one selected from Ag and Al, characterized in that the particle size of 10 ~ 50nm. Polyurethane water dispersion resin prepared according to any one of claims 1 to 4. 30 to 60% by weight of the polyurethane water dispersion resin of claim 5, 20 to 30% by weight of water, 10 to 20% by weight of solvent, 10 to 20% by weight of white pigment, 5 to 10% by weight of sieving pigment, 0.1 to 1.0% by weight of antifoaming agent , 0.1 to 3.0 wt% thickener, 0.1 to 3.0 wt% hardener and 0.1 to 1.0 wt% pH adjuster.