KR20120108730A - Composition of waterborne polyurethane, method of the composition and coating paint including the same - Google Patents

Abstract

PURPOSE: A water-dispersible polyurethane composition is provided to improve mechanical properties like abrasion resistance, hardness, etc without using inorganic materials like clay, silica and alumina. CONSTITUTION: A manufacturing method of water-dispersible polyurethane composition comprises a step of manufacturing a prepolymer with a NCO group in terminal by reacting dimethylol propionic acid, an isocyanate-based compound and a catalyst to polyol; a step of manufacturing a prepolymer with an acrylate group in terminal by reacting pentaerythritol triacrylate to the reaction solution; a step of neutralizing a dimethylolpropionic acid-derived carboxy group originated from dimethylolpropionic acid by adding a neutralizer to the reaction solution of pH 7-10; and a step of manufacturing water-dispersible solution by mixing the reaction solution and water.

Description

Composition of waterborne polyurethane, method of the composition and coating paint including the same}

The present invention relates to a water-dispersed polyurethane composition, a method for manufacturing the same, and a coating paint including the same, which can increase mechanical properties such as abrasion resistance and hardness of a coating film without using inorganic materials.

In the case of urethane compositions generally used in various coating or adhesive fields, an organic solvent has been used as a solvent. As the urethane composition releases volatile organic compounds in the drying process, environmental pollution is emerging as a serious social problem.

As a result, regulations around the world to prevent the pollution of volatile organic compounds, to prevent global warming, and to prevent the destruction of ozone layer are being followed. According to this social trend, various technologies related to the production of water-dispersed polyurethane using water instead of an organic solvent have been studied.

In the case of a water-dispersed polyurethane, if the chemical crosslinking structure is not sufficiently formed, thermal stability, chemical resistance, water resistance, and mechanical properties such as wear resistance and hardness are deteriorated, thereby limiting its application. In order to compensate for the insufficient mechanical properties of the water-dispersed polyurethane, studies have been conducted to introduce inorganic materials such as clay, silica, and alumina into the resin.

As a result of the study, it is known that addition of tetraethyl orthosilicate to water-dispersed polyurethane improves mechanical properties such as abrasion resistance and hardness, and that mechanical properties are improved when mixing colloidal silica into water-dispersed polyurethane. . However, when an inorganic substance is added to the water-dispersed polyurethane, not only it is difficult to maintain a stable dispersion state but also the viscosity rises, resulting in a decrease in workability and deterioration in adhesion to the substrate.

In order to solve the above problems, the present inventors have repeatedly studied to improve mechanical properties such as abrasion resistance and hardness of a water-dispersed polyurethane composition without adding an inorganic substance. In this case, it was found that the mechanical properties of the water-dispersed polyurethane composition can be greatly improved without the addition of an inorganic material, and thus the present invention was completed.

It is an object of the present invention to provide a water-dispersible polyurethane composition which can improve mechanical properties such as wear resistance and hardness without using inorganic materials such as clay, silica and alumina.

It is another object of the present invention to provide a method for producing a water-dispersed polyurethane with improved mechanical properties such as wear resistance and hardness without including inorganic materials.

It is another object of the present invention to provide a coating material for coating comprising the water-dispersed polyurethane composition.

Method for producing a water-dispersed polyurethane composition according to the present invention for achieving the above object is 5 to 10 parts by weight of dimethylol propionic acid, diisocyanate compound 20 with respect to 100 parts by weight of polyol having a number average molecular weight of 500 to 2000 A first step of preparing a prepolymer having an NCO group at the end by adding to 60 parts by weight and 0.001 to 0.1 parts by weight of a catalyst and reacting; 10 to 25 parts by weight of pentaerythritol triacrylate is added to the reaction solution of the first step and reacted for 3 to 8 hours to introduce an acrylate group to the NCO group to prepare a prepolymer having an acrylate group at the terminal; A third step of neutralizing the carboxyl group derived from dimethylol propionic acid by adding a neutralizing agent to the reaction solution of the second step until the pH is 7 to 10; And a fourth step of preparing an aqueous dispersion solution by mixing the reaction solution of the third step with 250 to 550 parts by weight of water.

The polyol is a polycarbonate diol, and the diisocyanate compound is preferably isophorone diiocyanate.

A fourth step of adding 1 to 5 parts by weight of the chain extender to the aqueous dispersion solution of the fourth step and reacting.

The fourth step may be to slowly add the water to the reaction solution of the third step and then to stir or to slowly add the reaction solution of the third step to the water and then to stir.

The water-dispersed polyurethane composition according to the present invention for achieving the above object of the present invention is characterized in that it is prepared by the production method.

Coating paints according to the present invention for achieving another object of the present invention is characterized in that it comprises the water-dispersed polyurethane composition.

The above-described water-dispersed polyurethane composition according to the present invention prepares a prepolymer having an NCO group at its end in the preparation process, and then introduces an acrylate group into the NCO group using pentaerythritol triacrylate and then disperses the inorganic material. It is possible to obtain the effect of improving mechanical properties such as wear resistance and hardness without using. In particular, when pentaerythritol triacrylate is used as compared with the case of using other kinds of acrylate compounds, remarkably improved wear resistance and hardness characteristics can be obtained. The water-dispersed polyurethane composition according to the present invention can be utilized in various coating paints.

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

The method for preparing a water-dispersed polyurethane composition according to the present invention is a first step of preparing a prepolymer having an NCO group at the end by mixing and reacting a polyol, dimethylol propionic acid, a diisocyanate compound, and a catalyst. Pentaerythritol triacrylate is added to the reaction solution and reacted to introduce an acrylate group to the NCO group to prepare a prepolymer having an acrylate group at the end, and to neutralize the reaction solution by adding a neutralizing agent to the reaction solution of the second step. And a fourth step of preparing an aqueous dispersion solution by mixing the reaction solution and water of the third step and the third step. The manufacturing method of the water-dispersed polyurethane composition may further comprise a fifth step of reacting by adding a chain extender to the water dispersion solution of the fourth step.

The manufacturing method will be described in detail for each step as follows.

First stage

The first step is to prepare a prepolymer having an NCO group at the end by mixing and reacting a polyol, dimethylol propionic acid, a diisocyanate compound and a catalyst.

Specifically, in order to prepare a prepolymer having an NCO group at the terminal, 5 to 10 parts by weight of dimethylolpropionic acid and 20 to 60 parts by weight of a diisocyanate compound based on 100 parts by weight of a polyol having a number average molecular weight of 500 to 2000 And 0.001 to 0.1 parts by weight of catalyst were added and reacted.

When the polyol has a number average molecular weight of 500 to 2000 is used, when the polyol number average molecular weight is less than 500, the dispersion stability is poor, there is a disadvantage in poor workability when applying the coating, the number average molecular weight exceeds 2000 When applied to the coating has a disadvantage in that the flexibility of the coating film is increased so that the overall physical properties. Therefore, it is preferable to use a polyol having a molecular weight within the above range. More preferably, the number average molecular weight is 800-1500.

As the polyol, polyester polyol, carbonate polyol, caprolactone polyol and the like can be used. Preferably, carbonate polyols are used.

Polyester polyols are generally commercially available and are obtained by condensation of diacids or acid anhydrides with glycols. Diacids can be used either saturated or unsaturated and alkyl or cyclic alkyl and phenyl. Examples include phthalic acid, hydrozinnate phthalic acid, isoplic acid, tellaflic acid, malonic acid, succinic acid, glutamic acid, adipic acid, pimelic acid, sublic acid, azeratic acid, sebacic acid, formic acid, succinic anhydride , Phthalic anhydride, maleic anhydride, hydrozinnate phthalic anhydride and the like. Alkyl glycols are generally used as glycols. Examples are ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, methyl propane glycol, neopentyl glycol, butylethyl flopane glycol, butanediol, hexane diol and the like.

In the case of carbonate polyols, commercially available polycarbonate diols of Asahi Kasai Corporation can be used.

In the case of caprolactone-based polyols, epsilon caplolactone-modified products can be used, and the commercialized lactone polyol Placcel 200 series of Daicel can be optionally used.

The dimethylol propionic acid is used for the introduction of a hydrophilic group, when the addition amount is less than 5 parts by weight with respect to 100 parts by weight of polyol has a disadvantage in that the smooth dispersion is difficult, the stability is lowered, the addition amount may exceed 10 parts by weight When applied to the undercoat coating has a disadvantage that the chemical resistance is lowered. Therefore, it is preferable to add 5-10 weight part of dimethylol propionic acids with respect to 100 weight part of polyols.

In this case, the dimethylol propionic acid may be added in a state dissolved in a solvent, for example, may be added by dissolving in a solvent such as N-methyl-2-pyrrolidone, methanol or ethanol. Preferably the solvent is N-methyl-2-pyrrolidone, the solvent can be dissolved by adding 120 parts by weight or more, preferably 120 to 200 parts by weight based on 100 parts by weight of dimethylol propionic acid.

The diisocyanate compound is added in an amount of 20 to 60 parts by weight based on 100 parts by weight of the polyol. At this time, when the amount of the diisocyanate compound added is less than 20 parts by weight based on 100 parts by weight of polyol, the resulting urethane bonds are small, resulting in a lack of flexibility of the coating. When the amount of the diisocyanate compound exceeds 60 parts by weight, there is a problem in that the peelability of the paint increases, resulting in poor workability and deterioration in overall coating properties. Therefore, it is preferable to add 20-60 weight part of addition amounts of a diisocyanate type compound with respect to 100 weight part of polyols.

As the diisocyanate compound, most of the commercially available diisocyanate compound may be used. Toluene diisocyanate, diphenylmethane diisocyanate, xylene diisocyanate, isophorone diisocyanate, hexane diisocyanate, hexamethylene diisocyanate, etc. are mentioned as said diisocyanate type compound. These can be used individually or in combination of 2 or more, respectively. Preferably, isophorone diisocyanate is used.

A catalyst is used to accelerate the reaction. The catalyst may be added within the usual range of the catalyst used in the production of conventional polyurethane. For example, the catalyst may be added in an amount of 0.001 to 0.1 parts by weight based on 100 parts by weight of polyol, and a usable catalyst may include dibutyltin dilaurate (DBDTL).

At this time, the reaction is carried out for 3 hours or more in the state of raising the temperature of the reaction vessel to 70 to 90 ℃, the end of the reaction is easily confirmed through the change in the absorption band length of the isocyanate group (NCO), for example in the IR spectrum Can be.

If it is as mentioned above, the prepolymer which has NCO group at the terminal is possible.

2nd step

In the second step, pentaerythritol triacrylate is added to the reaction solution of the first step and reacted to prepare a prepolymer having an acrylate group at the terminal by introducing an acrylate group to the NCO group.

More specifically, to prepare a prepolymer having an acrylate group at the terminal, in the present invention, 10 to 25 parts by weight of pentaerythritol triacrylate is added to the reaction solution of the first step and reacted for 3 to 8 hours to introduce an acrylate group to the NCO. It was prepared by.

In order to impart acrylic resin properties, an acrylate monomer is used. In the present invention, pentaerythritol triacrylate was used. When pentaerythritol triacrylate is used, mechanical properties such as wear resistance and hardness can be improved without using inorganic materials. In particular, when pentaerythritol triacrylate is used, remarkably improved mechanical properties can be obtained compared to the case of using other kinds of acrylate compounds.

Conventional techniques for using acrylate monomers in water-dispersed polyurethane compositions are known. However, a technique of using pentaerythritol triacrylate in the same manner as in the present invention in order to improve mechanical properties such as wear resistance and hardness has not been disclosed.

The pentaerythritol triacrylate can significantly improve the mechanical properties by controlling the amount of the pentaerythritol triacrylate. The pentaerythritol triacrylate is preferably added in an amount of 10 to 25 parts by weight based on 100 parts by weight of the polyol used in the first step. If the addition amount of the pentaerythritol triacrylate is less than 10 parts by weight, it is difficult to expect the improvement of mechanical properties, and if the addition amount exceeds 25 parts by weight, there is a problem in that the wear resistance is lowered and the adhesive strength is lowered.

When the reaction is carried out for 3 to 8 hours in a state where the temperature of the reaction vessel is raised to 70 to 90 ° C., the prepolymer having an acrylate group at the terminal into which the acrylate group is introduced can be easily prepared.

Step 3

The third step is a step of neutralizing by adding a neutralizing agent to the reaction solution of the second step.

Specifically, in order to neutralize the second reaction solution, the neutralizing agent was added to the reaction solution of the second step until the pH was 7 to 10 to neutralize the carboxyl group derived from dimethylol propionic acid.

The neutralizing agent may be ammonia, ethylamine, butylamine, dimethylamine, diisopropylamine, dimethylethylamine, benzylamine, ethanolamine, diethanolamine, triethanolamine, tributylamine, methyl diethanolamine, diethylethanolamine, Dimethylethanolamine, normal methylmorpholine, diisopropanolamine or 2-amino2-methyl1-propanol may be used, and preferably diethylethanolamine is used.

The addition of the neutralizing agent is preferably carried out in the state of lowering the temperature of the reaction vessel to 50 ℃ or less.

Step 4

The third step is to prepare a dispersion solution by mixing the reaction solution and water.

More specifically, in order to obtain an aqueous dispersion solution, the reaction solution of the third step and 250 to 550 parts by weight of water were mixed to prepare an aqueous dispersion solution.

In the fourth step, two methods may be considered to prepare an aqueous dispersion solution. That is, water may be slowly added to the reaction solution of the third step and then stirred to prepare an aqueous dispersion solution, or by slowly adding the reaction solution to the third step and then stirred to prepare an aqueous dispersion solution.

In the fourth step, if necessary, some alcohol solvents may be used for the purpose of improving workability. For example, a very small amount of methanol, ethanol, isopropanol, butanol, methylcellulose, ethyl solusorb, etc. may be used.

The amount of the water added need not be limited, but may be added in an amount of 250 to 550 parts by weight based on 100 parts by weight of the polyol. If the added amount of water is less than 250 parts by weight based on the above standards, the coating property is lowered, and if it exceeds 550 parts by weight, it is difficult to form a coating film (coating layer) having a desired thickness.

Step 5

The fifth step is to be added selectively to control the molecular weight is to add a chain extender to the aqueous dispersion solution of the fourth step to react.

More specifically, the fifth step may be to add and react 1 to 5 parts by weight of a chain extender to the aqueous dispersion solution of the fourth step.

The chain extender may use diamines and diol compounds, specifically, a compound containing two primary or secondary amino groups and two hydroxyl groups, ethylenediamine, propylenediamine, butylenediamine, pentylenediamine, hexamethylenediamine , Ethylenediol, propylenediol, butylenediol, pentylenediol, hexamethylenediol can be used by mixing at least one or more.

The chain extender is preferably added 1 to 5 parts by weight based on 100 parts by weight of the polyol used in the first step. In addition, the chain extender is preferably added after dilution in a small amount of water.

The water-dispersed polyurethane composition according to the present invention prepared by the above method can be usefully used as a coating paint, in particular, mobile phone undercoat coating, when applied to the coating paint has excellent mechanical properties such as wear resistance and hardness In addition to exhibiting excellent physical properties such as viscosity and adhesion.

The water-dispersed polyurethane composition according to the present invention described above may include various additives within a range that does not change the properties of the present invention. Antioxidants, UV absorbers, light stabilizers, thermal polymerisation inhibitors, leveling agents, including, for example, antistatic agents selected from conductive polymers, quaternary ammonium salts, inorganic salts, metal particles, (meth) acrylate modified quaternary ammonium salts , Surfactants, lubricants and the like may additionally be used within the usual addition range.

The present invention provides a coating paint comprising the water-dispersed polyurethane composition prepared as described above. The water-dispersed polyurethane composition in the coating paint can be variously controlled in content, preferably 40 parts by weight or more, more preferably 40 to 90 parts by weight based on 100 parts by weight of the total coating paint.

The coating paint may be used by mixing a variety of additives, such as glitters, pigments, such as silver powder and pearl used in the art known in the art. In addition, a polyisocyanate curing agent may be optionally used for improving physical properties of the coating paint. The glitter may be coated aluminum powder, copper powder, pearl, or the like.

Hereinafter, the present invention will be described in more detail with reference to the following examples, which are only presented to aid the understanding of the present invention and the present invention is not limited thereto.

<Examples 1 to 3 and Comparative Examples 1 to 3>

Into a 500 mL four-necked reactor with a thermometer, cooler, thermostat and stirrer, 30 g of polycarbonate diol (Asahi Kasei) having a molecular weight of 1000, 13 g of isophorone diisocyanate, and 0.005 g of DBTL were added to a polyol, followed by dimethylol propionic. 2 g of acid (DMPA) was dissolved in 6 g of NMP, and then stirred at 75 ° C. for 3 hours. Pentaerythritol triacrylate was added to the reaction solution in an amount shown in Table 1 below, followed by reaction for 4 hours. After the reaction, the temperature was lowered to 50 ° C. and neutralized by the slow addition of triethylamine (TEA).

After the neutralization reaction, 120 g of distilled water was slowly added to the reaction vessel, and an aqueous dispersion solution was prepared while stirring at 1000 rpm.

2 g of ethylenediamine (EDA) was added to 8 g of ultrapure water, and the diluted solution was added to the aqueous dispersion solution and stirred for 1 hour to prepare a water dispersion polyurethane composition.

Pentaerythritol triacrylate
Addition amount (g) Example 1 4.5 Example 2 6.0 Example 3 7.2 Comparative Example 1 0 Comparative Example 2 1.0 Comparative Example 3 8.0

&Lt; Comparative Example 4 &

A water-dispersed polyurethane composition was prepared in the same manner as in Example 1 except that 2-hydroxyethyl methacrylate was used instead of pentaerythritol triacrylate.

&Lt; Comparative Example 5 &

A water-dispersed polyurethane composition was prepared in the same manner as in Example 1 except that 2-hydroxyethyl acrylate was used instead of pentaerythritol triacrylate.

&Lt; Comparative Example 6 >

Into a 500 mL four-necked reactor with a thermometer, cooler, thermostat and stirrer, 30 g of polycarbonate diol (Asahi Kasei) having a molecular weight of 1000, 13 g of isophorone diisocyanate, and 0.005 g of DBTL were added to a polyol, followed by dimethylol propionic. 2 g of acid (DMPA) was dissolved in 6 g of NMP, and then stirred at 75 ° C. for 3 hours. After the reaction, the temperature was lowered to 50 ° C. and neutralized by the slow addition of triethylamine (TEA). Add 4.5 g of tetraethylorthosilicate to this 120 g of distilled water was slowly added thereto, and an aqueous dispersion solution was prepared while stirring at 1000 rpm.

2 g of ethylenediamine (EDA) was added to 8 g of ultrapure water, and the diluted solution was added to the aqueous dispersion solution and stirred for 1 hour to prepare a water dispersion polyurethane composition.

<Experimental Example>

Using the water-dispersed polyurethane composition prepared in the above Examples and Comparative Examples, the physical properties were evaluated as shown below, and the results are shown in Table 2.

1. Pencil Hardness

The water-dispersed polyurethane composition was spin coated on a stainless plate and then thermally cured (140 ° C., 30 minutes) to form a coating film. The thickness of the coating film was about 10 μm.

Pencil hardness of the coating film was a pencil hardness measurement (CORE TECH) was inserted into the pencil hardness measuring pencil at a 45 ° angle and the load of 1Kg was measured pencil hardness. Pencils were made using Mitsubishi products, and were carried out five times for each pencil hardness. If there were two or more Gis, it was judged to be defective, and pencil hardness was expressed by a pencil before the failure determination.

Kiss: 0 OK

Kiss: 1 OK

Ges: 2 or more NG

2. Wear resistance

The water-dispersed polyurethane composition was spin-coated on a PC (polycarbonate) substrate and then thermally cured (140 ° C., 30 minutes) to form a coating film. The thickness of the coating film was about 10 μm.

At this time, in order to measure the wear resistance of the coating film, the transmittance of the coating film was measured at 600 nm wavelength by UV-Vis spectrometer after abrasion of the coating film with a wear resistance wheel of 500 g under the conditions of 70 rpm and 100 revolutions.

The wear resistance of the coating film was defined as a transmission loss% (Transmittance Loss%) as shown in Equation 1 below, which means that the lower the transmittance loss rate, the better the wear resistance of the sample.

&Quot; (1) &quot;

Transmittance Loss% = 100 (B-A) / B

In Equation 1, A represents a transmittance at 600 nm after the wear of the coating coating with the wear wheel, B represents a transmittance at 600 nm before the wear of the coating coating with the wear wheel.

3. Viscosity

Viscosity was measured at 19 ° C. using a rotary viscometer (LVDV-11 + P, BROOKFIELD, USA). The spindle used was 62.

4. Adhesion

The water-dispersed polyurethane composition was spin coated on a stainless plate and then thermally cured (140 ° C., 30 minutes) to form a coating film. The thickness of the coating film was about 10 μm.

100 square columns of vertical and vertical 1 mm on the coated film as described above was attached to the transparent OPP tape of 50 mm width on it and then peeled off strongly and the adhesion was evaluated by counting the number of remaining graduations.

Pencil hardness Abrasion resistance
(Transmittance Loss (%) Viscosity (P) Adhesion Example 1 7H 25 0.22 100 Example 2 8H 15 0.24 100 Example 3 8H 10 0.24 100 Comparative Example 1 3H 61 0.20 100 Comparative Example 2 4H 58 0.21 100 Comparative Example 3 8H 17 0.24 95 Comparative Example 4 6H 52 0.21 100 Comparative Example 5 6H 51 0.21 100 Comparative Example 6 4H 50 0.50 92

When comparing the Examples 1 to 3 and Comparative Examples 1 to 3 carried out while changing the content of pentaerythritol triacrylate in the process of preparing the water-dispersed polyurethane composition as shown in Table 2, the content of the present invention In the case of the examples included in the preferred range of compared to the Comparative Examples 2 and 3, the content is out of the scope of the present invention is excellent in wear resistance and pencil hardness, it can be confirmed that both excellent viscosity and adhesive strength. In the case of Comparative Example 3, as the excess pentaerythritol triacrylate was added, it can be confirmed that the adhesive strength is somewhat inferior. Comparative Example 1 corresponds to a case where no pentaerythritol triacrylate is added, and the physical properties thereof may be remarkably inferior to Examples 1 to 3.

In addition, Comparative Examples 4 and 5 correspond to the case where another kind of acrylate compound is used instead of pentaerythritol triacrylate, and it can be confirmed that the wear resistance is largely inferior.

In particular, the water-dispersed polyurethane composition of the embodiment according to the present invention has excellent abrasion resistance and pencil hardness, excellent viscosity and adhesive strength, etc., as compared with the water-dispersed polyurethane composition incorporating an inorganic substance as in Comparative Example 6 according to the conventional method. You can see that.

Therefore, when the pentaerythritol triacrylate is used within a predetermined range in the process of preparing the water-dispersed polyurethane composition, it can be confirmed that the mechanical properties such as wear resistance and hardness can be greatly improved.

Claims (7)

5 to 10 parts by weight of dimethylol propionic acid, 20 to 60 parts by weight of isocyanate compound and 0.001 to 0.1 parts by weight of catalyst are added to 100 parts by weight of polyol of 500 to 2000 to react to prepare a prepolymer having an NCO group at the terminal. Stage 1;
10 to 25 parts by weight of pentaerythritol triacrylate is added to the reaction solution of the first step and reacted for 3 to 8 hours to introduce an acrylate group to the NCO group to prepare a prepolymer having an acrylate group at the terminal;
A third step of neutralizing the carboxyl group derived from dimethylol propionic acid by adding a neutralizing agent to the reaction solution of the second step until the pH is 7 to 10; And
And a fourth step of preparing an aqueous dispersion solution by mixing the reaction solution of the third step with 250 to 550 parts by weight of water. The method of claim 1, wherein the polyol is a polycarbonate diol, and the isocyanate compound is isophorone diiocyanate. The method of claim 1, further comprising a fifth step of reacting by adding 1 to 5 parts by weight of a chain extender to the aqueous dispersion solution of the fourth step. The method of claim 1, wherein the fourth step is to slowly add water to the reaction solution of the third step and then stir. The method of claim 1, wherein the fourth step is a method of producing a water-dispersed polyurethane composition, characterized in that the reaction solution of step 3 is slowly added to water and then stirred. Dispersed polyurethane composition, characterized in that produced by the method of any one of claims 1 to 5. A coating material comprising the water dispersion polyurethane composition of claim 6.