KR100962976B1 - Water soluble polyurethane resin for coating, the method for preparing the same and article thereof - Google Patents

Abstract

The present invention relates to an aqueous polyurethane resin for coating, a method for preparing the same, and a product thereof, and more particularly, to a method for preparing an aqueous polyurethane resin for coating, in the presence of a catalyst, a diol having a polyol, a diisocyanate, and a hydrophilic group. To prepare a prepolymer by reacting a diamine having a hydrophilic group or a mixture thereof, neutralizing the prepolymer with a neutralizing agent and adding water as a dispersion medium to prepare an aqueous dispersion, and then adding a chain extender to the aqueous dispersion to perform a chain extension reaction. To obtain a polyurethane water dispersion, wherein the NCO / OH ratio defined as (moles of diisocyanate) ÷ (moles of polyol + moles of hydrophilic group-containing diol) is 1.1 to 3.0, and a diol having the hydrophilic group. , The content of diamines having hydrophilic groups or mixtures thereof is the solid content of the final aqueous polyurethane polymer. It relates to a method for producing an aqueous polyurethane resin for coating, characterized in that 1 to 10% by weight relative to the aqueous polyurethane resin for coating prepared by the above method, and a product to which the resin is applied. Polyurethane resin of the present invention is excellent in water resistance, flex resistance and water dispersion stability has an advantage suitable for the surface coating of various products.

Polyurethane, Resin, Diisocyanate, Polyol, Water Dispersion, Flex Resistance

Description

Water-soluble polyurethane resin for coating, the method for preparing the same and article else}

The present invention relates to an aqueous polyurethane resin for coating, a method for manufacturing the same, and a product thereof, and more specifically, to the number of moles of diisocyanate group (NCO) and the number of hydroxyl groups (OH), which are reactive components in the preparation of the aqueous polyurethane resin. Water-based polyurethane resin for coating, a method for preparing the same, and a resin having excellent physical properties and excellent water resistance, bending resistance, and dispersion stability by controlling the content of diol and / or diamine having a hydrophilic group (carboxyl group). To the applied product.

Conventionally, various resins such as urethane resins, acrylic resins, epoxy resins, vinyl chloride resins, melamine resins have been used as coating agents, and in particular, solvent-type polyurethane resins that can satisfy high functionality and sensitivity have been mainly used. .

Polyurethane resin for coating is required to have excellent weather resistance, heat resistance, and film properties. Solvent-type polyurethane resins, which are widely used in the past, have a low flash point, which is a fire hazard and contains a large amount of highly toxic organic solvents, causing environmental pollution. It also has disadvantages that are not good for the working environment.

In response to this, there has been an increasing demand for an aqueous coating using water as a dispersion medium with extremely low adverse effects on the human body or the environment.

However, since the polyurethane itself is extremely hydrophobic, a method of forcibly dispersing the hydrophobic polyurethane using a large amount of emulsifier to make it aqueous and a method of introducing a hydrophilic group into the polyurethane skeleton to make a self-emulsifying resin and then dispersing it in water. (US Pat. No. 4,066,591, US Pat. No. 4,147,679, US Pat. No. 4,857,565, and US Pat. No. 5,552,496).

In particular, research on self-emulsifying resins has been actively conducted due to the inconvenience of using an emulsifier and the physical weakness of the polyurethane resin due to the emulsifier, but it is still sufficiently satisfactory in water resistance, flex resistance, and dispersion stability. It does not represent.

Accordingly, in the present invention, as a result of extensive research to solve the above problems, the number of moles of the diisocyanate group (NCO) and the number of hydroxyl groups (OH) of the reaction components in the preparation of the aqueous polyurethane resin is adjusted, and the hydrophilic group (carboxyl group) By limiting the content of diol and / or diamine having a) it was possible to prepare an aqueous polyurethane resin for coating excellent in the physical properties of the film and excellent in water resistance, bending resistance, water dispersion stability, etc., the present invention was completed based on this .

Accordingly, an object of the present invention is to provide a method for producing an aqueous polyurethane resin for coating which is environmentally friendly and can satisfy various physical properties such as water resistance, flex resistance, and water dispersion stability.

Another object of the present invention is to provide an aqueous polyurethane resin for coating prepared by the above method.

Still another object of the present invention is to provide a product to which the resin is applied.

Method for producing an aqueous polyurethane resin for coating of the present invention for achieving the above object is a diol having a polyol, diisocyanate, and a hydrophilic group, diamine having a hydrophilic group in the presence of a catalyst in the production method of the coating aqueous polyurethane resin Or a mixture of these to prepare a prepolymer, neutralize the prepolymer with a neutralizing agent, add water as a dispersion medium to prepare an aqueous product, and then add a chain extender to the aqueous product to carry out a chain extension reaction to perform a polyurethane aqueous dispersion. Wherein the NCO / OH ratio defined by (moles of diisocyanate) ÷ (moles of polyol + moles of hydrophilic group-containing diol) is 1.1 to 3.0, diol having a hydrophilic group, diamine having a hydrophilic group Or 1 to 10% by weight, based on the solids content of the final aqueous polyurethane polymer. It consists in.

Aqueous polyurethane resin for coating to achieve another object of the present invention is prepared by the above method, it is applied as a surface coating agent of a metal plate, electrical components, shoes, nylon fibers, polyester fibers or glass fibers another object of the present invention Can be achieved.

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

Looking at the process for producing an aqueous polyurethane resin for coating according to the invention, in the presence of a catalyst, a polyol, a diisocyanate, and a diol having a hydrophilic group, a diamine having a hydrophilic group or a mixture thereof are reacted to prepare a prepolymer, and then In addition, the prepolymer is neutralized with a neutralizing agent and water is prepared by adding water as a dispersion medium. A chain extender is added to the aqueous product thus obtained to carry out a chain extension reaction to obtain a polyurethane water dispersion. At this time, in the present invention, the NCO / OH ratio defined as (moles of diisocyanate) ÷ (moles of polyol + moles of hydrophilic group-containing diol) is 1.1 to 3.0, and diol having the hydrophilic group, diamine having a hydrophilic group, or a mixture thereof. The content is characterized by 1 to 10% by weight relative to the solids of the final aqueous polyurethane polymer.

First, looking at the process for producing the prepolymer, in the presence of a catalyst, a polyol, a diisocyanate, and a diol having a hydrophilic group, a diamine having a hydrophilic group or a mixture thereof are reacted to obtain a prepolymer.

The polyol used in the present invention may be used as one or two kinds of polyester-based polyols or polyether-based polyols having at least two hydroxyl groups at the molecular ends. The number average molecular weight of the said polyester polyol or polyether polyol is 200-10,000, Preferably it is 200-3,000, More preferably, it is 500-2,000.

The polyester-based polyol is obtained through a condensation reaction of dibasic acid and dihydric alcohol, and the dibasic acid is used by selecting one or two or more from adipic acid, azelaic acid, succinic acid, terephthalic acid, and isophthalic acid. The alcohol is one from ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, neopentylglycol, 2-methylpropanediol, 1,4-cyclohexanedimethanol, and bisphenol A or Select and use more than one.

The diisocyanate used in the present invention can be used both aliphatic, cycloaliphatic, and aromatic, but it is preferable to use one or two or more from aliphatic and cycloaliphatic diisocyanates. Examples of such diisocyanates include isophorone diisocyanate (IPDI), 1,6-hexamethylene diisocyanate (1,6-HDI), tetramethylxylene diisocyanate (1,3 or 1,4-TMXDI), and Methylenebiscyclohexane diisocyanate (4,4-H ₁₂ MDI) and the like.

Diols having a carboxyl group and diamines may be used alone or in combination in order to introduce a hydrophilic group in the preparation of the coating aqueous polyurethane of the present invention, and the diol having a carboxyl group may be dimethylol propionic acid (DMPA), and / or dimethyl. All butyric acid (DMBA) may be used, and as the diamine having a carboxyl group, one or more compounds represented by the following Chemical Formula 1 may be used.

In the above formula, R ₁ is an alkyl group having 2 to 10 carbon atoms, R ₂ and R ₃ are the same or different from each other, a hydrogen atom or an alkyl group having 1 to 2 carbon atoms.

The amount of diol and / or diamine having the hydrophilic group is used in an amount of 1 to 10% by weight relative to the final aqueous polyurethane polymer solids. do. If the amount thereof is less than 1% by weight, the water dispersion stability of the aqueous polyurethane is lowered. If the amount is more than 10% by weight, the particle size is too small and the water resistance is lowered.

The reaction for preparing the prepolymer is carried out in the presence of a catalyst, and preferred catalysts for the reaction include tin octoate, dibutyl tin dilaurate, dioctyl tin dilaurate, triethylenediamine, tin dichloride, or tin tetrachloride. .

On the other hand, in order to control the mechanical strength of the final aqueous polyurethane polymer in the preparation of the prepolymer, a monomolecular weight of diol may optionally be used. The monomolecular weight diol is one from ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, neopentylglycol, 2-methylpropanediol, and 1,4-cyclohexanedimethanol Or two or more may be mixed and used.

In addition, a polyether having a molecular weight of 500 to 1,500 having a primary hydroxyl group or an amino group at one end of the molecule may be selectively used for storage stability of the prepolymer in a water-dispersed state, the amount of which is used based on 10 parts by weight of the aqueous polyurethane polymer solids. Use less than%

Polyethers having a primary hydroxyl or amino group at one end can be synthesized as described in US Pat. Nos. 3,905,929 and 3,920,598, and modified structures thereof are possible.

The reaction ratio of each component constituting the prepolymer may be defined as a molar ratio of NCO / OH. For example, the ratio of NCO / OH defined by (moles of diisocyanate) ÷ (moles of polyol + moles of diol having a hydrophilic group) is reacted in the range of 1.1 to 3.0. In addition, when the monomolecular weight diol and / or polyether having a hydroxyl group or an amino group at one end of the molecule participates in the reaction, the molar ratio of NCO / OH is (moles of diisocyanate) ÷ (moles of polyol + hydrophilic group). Number of moles of diol having + monomolecular weight of diol and / or number of moles of polyether having hydroxyl group at one end of the molecule). In this case also the ratio of NCO / OH is in the range of 1.1 to 3.0.

The ratio of NCO / OH is adjusted according to the required film properties, and is low to obtain a flexible film, and high to obtain a hard film. If the NCO / OH ratio is less than 1.1, the film becomes soft, but the physical strength is not good, and the viscosity of the prepolymer is too high, making it difficult to disperse.

The prepolymer thus prepared has isocyanate groups at both ends. Neutralizers for neutralizing prepolymers having isocyanate groups at both ends are trimethylamine, triethylamine, triisopropylamine, tributylamine, N, N-dimethyl cyclohexylamine, N, N-dimethylaniline, N, N- Tertiary amines, such as dimethyl aminoethanol and N-methylmorpholine, are used, or inorganic bases, such as sodium hydroxide, potassium hydroxide, and lithium hydroxide, can be used. The amount of the neutralizer used is 80 to 120 mol% of the number of moles of diol and / or diamine having a total hydrophilic group used in the production of an aqueous polyurethane.

According to the present invention, an aqueous dispersion of the prepolymer can be obtained while adding water as a dispersion medium while stirring the neutralized prepolymer. Then, a chain extension reaction is performed by adding a chain extender to the aqueous dispersion to obtain an aqueous polyurethane resin.

On the other hand, the prepolymer may be dissolved in an organic solvent in order to lower the viscosity of the prepolymer to facilitate water dispersion before neutralizing with a neutralizing agent, and then neutralized with a neutralizing agent. Next, water as a dispersion medium is added to obtain an aqueous dispersion of the prepolymer. The organic solvent is subjected to a chain extension reaction, which is a subsequent process, and then removed by distillation under reduced pressure. Preferred organic solvents include acetone, methyl ethyl ketone, isopropyl alcohol, and ethanol. Can be used.

The chain extender used in the present invention uses a polyamine compound containing two or more primary or secondary amino groups, and includes hydrazine, ethylene diamine, diethylene triamine, triethylene tetraamine, 1,5-diaminohexane, One or two or more are used in combination from isophorone diamine, dicyclohexylmethylene diamine, 1,6-hexamethylene diamine and piperazine. The amount of the chain extender used is preferably 80 to 100% of the theoretical equivalent required to prepare the final aqueous polyurethane polymer.

After the chain extension reaction is completed, an aqueous coating polyurethane having excellent stability and physical properties of 40 to 50% of solid content concentration can be obtained. The resin of the present invention may optionally further include a viscosity modifier, a curing agent and the like. The coating aqueous polyurethane thus prepared is made of a linear anionic polyurethane having a relatively high molecular weight.                     

On the other hand, the coating water-based polyurethane resin is applied as a surface coating agent to products such as metal plates, electrical components, shoes, nylon fibers, polyester fibers or glass fibers to exhibit excellent water resistance, flex resistance, water dispersion stability and the like.

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

Example 1

150 g of a polyester polyol having a molecular weight of 1,000, 16.2 g of dimethylol butyric acid, 68.7 g of isophorone diisocyanate and 0.32 of tin octoate used as a catalyst prepared by condensation of 178 g of 1,6-hexanediol and 146 g of adipic acid The reaction is carried out at 90 DEG C for 3 hours to prepare a polyurethane prepolymer having a carboxyl group in the molecular chain and an isocyanate group at both ends.

The prepared polyurethane prepolymer was cooled to 60 ° C. and then neutralized by addition of 11.1 g of triethylamine. 373 g of water are added with rapid stirring of the neutralized prepolymer to obtain an aqueous dispersion of the prepolymer.

Here, 3 g of 1,6-hexamethylene diamine was dissolved in water and added dropwise thereto, followed by stirring for 2 hours to proceed the chain extension reaction to obtain a polyurethane water dispersion having a solid content of 40%.

Example 2

150 g of a polyester polyol having a molecular weight of 1,000, 16.2 g of dimethylol butyric acid, 81 g of methylenebiscyclohexane diisocyanate, and 0.32 g of tin octoate as a catalyst prepared by condensation of 178 g of 1,6-hexanediol and 146 g of adipic acid The reaction was carried out at 90 DEG C for 3 hours to prepare a polyurethane prepolymer having a carboxyl group in the molecular chain and an isocyanate group at both ends.

The prepared polyurethane prepolymer was cooled to 60 ° C. and then neutralized by addition of 11.1 g of triethylamine. 391 g of water are added with rapid stirring of the neutralized prepolymer to obtain an aqueous dispersion of the prepolymer.

Here, 3 g of 1,6-hexamethylene diamine was dissolved in water and added dropwise thereto, followed by stirring for 2 hours to carry out a chain extension reaction to obtain a polyurethane water dispersion having a solid content of 40%.

Example 3

A polyether having a molecular weight of 750 having a primary hydroxyl group at one end of the molecule, 130 g of polyester polyol having a molecular weight of 1,000, 6.62 g of dimethylol butyric acid prepared by condensation of 178 g of 1,6-hexanediol and 146 g of adipic acid 3.83 g, 2-methylpropanediol, 63 g of isophorone diisocyanate and 0.1 g of tinoctoate were added to the catalyst and reacted at 90 ° C. for 3 hours to prepare a polyurethane prepolymer having a carboxyl group in the molecular chain and an isocyanate group at both ends. do.

The prepared polyurethane prepolymer was cooled to 60 ° C., and then 220 g of acetone was added to completely dissolve the prepolymer, followed by neutralization by addition of 4.5 g of triethylamine. 323 g of water was added thereto, and 9.6 g of hexamethylene diamine was added dropwise by dissolving in water.

This was stirred for 2 hours to proceed the chain extension reaction, and the acetone in the solution was removed by distillation under reduced pressure to obtain a polyurethane aqueous dispersion having a solid content of 40%.

Example 4

130 g of a polyester polyol having a molecular weight of 1,000 prepared through the condensation reaction of 178 g of 1,6-hexanediol with 146 g of adipic acid, 3.83 g of a polyether having a molecular weight of 750 having a primary hydroxyl group at one end of the molecule, and 2-methylpropane 8.54 g of diol, 63 g of isophorone diisocyanate and 0.1 g of tinoctoate were added to the catalyst and reacted at 90 ° C. for 3 hours to prepare a polyurethane prepolymer having an isocyanate group at both ends of the polymer.

The prepared polyurethane prepolymer is cooled to 60 ° C., and then 215 g of acetone is added to completely dissolve the prepolymer. 4.3 g of 4-amino-2-aminomethylbutanoic acid, which is a diamine having a carboxyl group, is added to the molecular chain, followed by reaction for 10 minutes, followed by neutralization by addition of 3.3 g of triethylamine. 321 g of water was added thereto, and 3.1 g of 1,6-hexamethylene diamine was dissolved in water and added dropwise thereto.

This was stirred for 2 hours to proceed the chain extension reaction, and the acetone in the solution was removed by distillation under reduced pressure to obtain a polyurethane aqueous dispersion having a solid content of 40%.

Example 5

130 g of a polyester polyol having a molecular weight of 1,000 prepared by condensation of 178 g of 1,6-hexanediol and 146 g of adipic acid, 3.83 g of a polyether having a molecular weight of 750 having a primary hydroxyl group at one end of the molecule, 2-methylpropane 8.54 g of diol, 11.9 g of hexamethylene diisocyanate, 55.7 g of methylenebiscyclohexane diisocyanate and 0.1 g of tinoctoate were added to the catalyst and reacted at 90 ° C. for 3 hours to prepare a polyurethane prepolymer having an isocyanate group at both ends of the polymer.

The polyurethane prepolymer was cooled to 60 ° C., and then 220 g of acetone was added to completely dissolve the prepolymer. 4.3 g of 4-amino-2-aminomethylbutanoic acid, which is a diamine having a carboxyl group, is added to the molecular chain, followed by reaction for 10 minutes, followed by neutralization by addition of 3.3 g of triethylamine. 321 g of water was added thereto, and 3.1 g of hexamethylene diamine was added dropwise by dissolving in water.

This was stirred for 2 hours to proceed the chain extension reaction, and the acetone in the solution was removed by distillation under reduced pressure to obtain a polyurethane aqueous dispersion having a solid content of 40%.

Example 6

150 g of polyester polyol having a molecular weight of 1,000, 16.2 g of dimethylol butyric acid, 68.7 g of isophorone diisocyanate, and 0.32 g of tinoctoate used as a catalyst, prepared by condensation of 132 g of 1,4-butanediol and 146 g of adipic acid The reaction was carried out at 90 ° C. for 3 hours to prepare a polyurethane prepolymer having a carboxyl group in the molecular chain and an isocyanate group at both ends.

The prepared polyurethane prepolymer was cooled to 60 ° C. and then neutralized by addition of 11.1 g of triethylamine. 373 g of water are added with rapid stirring of the neutralized prepolymer to obtain an aqueous dispersion of the prepolymer.

Here, 3.0 g of 1,6-hexamethylene diamine was dissolved in water and added dropwise thereto, followed by stirring for 2 hours to proceed the chain extension reaction to obtain a polyurethane water dispersion having a solid content of 40%.                     

Example 7

155 g of neopentyl glycol and 146 g of adipic acid were added, and 150 g of a polyester polyol having a molecular weight of 1,000, 16.2 g of dimethylol butyric acid, 68.7 g of isophorone diisocyanate and 0.32 g of tin octoate used as a catalyst were added thereto. The reaction is carried out at 90 ° C. for 3 hours to prepare a polyurethane prepolymer having a carboxyl group in the molecular chain and an isocyanate group at both ends.

The prepared polyurethane prepolymer is cooled to 60 ° C. and then neutralized by addition of 11.1 g of triethylamine. 373 g of water are added with rapid stirring of the neutralized prepolymer to obtain an aqueous dispersion of the prepolymer.

Here, 3.0 g of hexamethylene diamine was dissolved in water and added dropwise thereto, followed by stirring for 2 hours to proceed the chain extension reaction to obtain a polyurethane water dispersion having a solid content of 40%.

Example 8

150 g of polytetramethylene glycol (PTMEG) polyol having a molecular weight of 1,000, 16.2 g of dimethylol butyric acid, 68.7 g of isophorone diisocyanate, and 0.32 g of tinoctoate used as a catalyst were added and reacted at 90 ° C. for 3 hours to carry out a carboxyl group in the molecular chain. To prepare a polyurethane prepolymer having isocyanate groups at both ends.

The prepared polyurethane prepolymer is cooled to 60 ° C. and then neutralized by addition of 11.1 g of triethylamine. 373 g of water are added with rapid stirring of the neutralized prepolymer to obtain an aqueous dispersion of the prepolymer.                     

To this, 3.0 g of 1,6-hexamethylene diamine was dissolved in water and added dropwise thereto, followed by stirring for 2 hours to proceed with a chain extension reaction to obtain a polyurethane water dispersion having a solid content of 40%.

Comparative Example 1

150 g of a polyester polyol having a molecular weight of 1,000, 1,6-hexanediol and 146 g of adipic acid, 2 g of dimethylol butyric acid, 68.7 g of isophorone diisocyanate and 0.3 g of tinoctoate used as a catalyst The reaction was carried out at 90 ° C. for 3 hours to prepare a polyurethane prepolymer having a carboxyl group in the molecular chain and an isocyanate group at both ends.

The prepared polyurethane prepolymer was cooled to 60 ° C. and neutralized by adding 1.36 g of triethylamine. 359 g of water are added with rapid stirring of the neutralized prepolymer to obtain an aqueous dispersion of the prepolymer.

Here, 16.9 g of 1,6-hexamethylene diamine was dissolved in water and added dropwise thereto, followed by stirring for 2 hours to perform a chain extension reaction to obtain a polyurethane water dispersion having a solid content of 40%.

Comparative Example 2

150 g of a polyester polyol having a molecular weight of 1,000 prepared through the condensation reaction of 178 g of 1,6-hexanediol with 146 g of adipic acid, 35 g of dimethylol butyric acid, 104.47 g of isophorone diisocyanate and 0.36 g of tinoctoate used as a catalyst The reaction was carried out at 90 ° C. for 3 hours to prepare a polyurethane prepolymer having a carboxyl group in the molecular chain and an isocyanate group at both ends.

The prepared polyurethane prepolymer was cooled to 60 ° C. and neutralized by adding 23.89 g of triethylamine. 485 g of water are added with rapid stirring of the neutralized prepolymer to obtain an aqueous dispersion of the prepolymer.

9.28 g of 1,6-hexamethylene diamine was dissolved in water and added dropwise thereto, followed by stirring for 2 hours to perform a chain extension reaction to obtain a polyurethane water dispersion having a solid content of 40%.

Comparative Example 3

150 g of polyester polyol with a molecular weight of 1,000, 1,6-hexanediol and 146 g of adipic acid, 16 g of dimethylol butyric acid, 58.9 g of isophorone diisocyanate and 0.28 g of tinoctoate used as a catalyst The reaction was carried out at 90 ° C. for 3 hours to prepare a polyurethane prepolymer having a carboxyl group in the molecular chain and an isocyanate group at both ends.

The prepared polyurethane prepolymer was cooled to 60 ° C. and then neutralized by adding 10.92 g of triethylamine. 355 g of water are added with rapid stirring of the neutralized prepolymer to obtain an aqueous dispersion of the prepolymer.

Here, 0.58 g of 1,6-hexamethylene diamine was dissolved in water and added dropwise thereto, followed by stirring for 2 hours to carry out a chain extension reaction to obtain a polyurethane water dispersion having a solid content of 40%.

Comparative Example 4                     

150g of polyester polyol having a molecular weight of 1,000, 1,6-hexanediol and 146g of adipic acid, 16g of dimethylol butyric acid, 202.3g of isophorone diisocyanate and 0.36g of tin octoate used as a catalyst The reaction was carried out at 90 ° C. for 3 hours to prepare a polyurethane prepolymer having a carboxyl group in the molecular chain and an isocyanate group at both ends.

The prepared polyurethane prepolymer was cooled to 60 ° C. and then neutralized by adding 10.92 g of triethylamine. 682 g of water is added with rapid stirring of the neutralized prepolymer to obtain an aqueous dispersion of the prepolymer.

Here, 75.4 g of 1,6-hexamethylene diamine was dissolved in water and added dropwise thereto, followed by stirring for 2 hours to perform a chain extension reaction to obtain a polyurethane water dispersion having a solid content of 40%.

The composition and properties of the coating aqueous polyurethane synthesized by the above Examples and Comparative Examples are summarized in Table 1 below.

Molar ratio of NCO / OH Hydrophilic group content (%) * Water dispersion stability * Water resistance * Flexibility Example 1 1.19 6.50 Good Good Good Example 2 1.19 6.19 Good Good Good Example 3 1.23 2.98 Good Good Good Example 4 1.23 2.17 Good Good Good Example 5 1.23 2.13 Good Good Good Example 6 1.19 6.47 Good Good Good Example 7 1.19 6.47 Good Good Good Example 8 1.19 6.47 Good Good Good Comparative Example 1 1.15 0.89 Bad Good Good Comparative Example 2 1.21 10.8 Good Bad Bad Comparative Example 3 1.02 6.76 Bad Bad Good Comparative Example 4 3.5 3.52 Bad Good Bad

1) NCO / OH molar ratio: (number of moles of diisocyanate) ÷ (number of moles of polyol + number of diols containing hydrophilic groups) + (optionally), diol of monomolecular weight and / or polyether having a primary hydroxyl group at one end of the molecule confiscation)

2) Hydrophilic group content (%): (Weight of hydrophilic group-containing diol and / or hydrophilic group-containing diamine weight) × 100 ÷ (Weight of solid content)

3) Water Dispersion Stability: Presence of sediment during water dispersion or when the final aqueous polyurethane solution is left at room temperature for one week.

Good: No deposits generated, Poor: Deposits

4) Water resistance: Comparison of retention rate of tensile strength compared to before leaving the film by leaving the final aqueous polyurethane solution at 50 ℃ for 3 days

   Good: (Tensile strength after standing) × 100 ÷ (Tensile strength before standing) is 80% or more

   Poor: (Tensile strength after neglect) × 100 ÷ (Tension strength before neglect) is less than 80%

5) Flex resistance: The final polyurethane solution is spray-coated onto the shoe polyurethane foam and dried to measure the time when cracks occur on the surface during the bending test using the Demattia Flexion Tester.

 Good: 100,000 or more, Poor: less than 100,000

In the case of the water-based polyurethane resin synthesized in Examples 1 to 8, both the water dispersion stability and the water resistance, the flex resistance and the like are all good at the same time, but in the case of the resin of the water-based polyurethane synthesized in Comparative Examples 1 to 4, water dispersion stability and water resistance, Flexural resistance and the like were not all good at the same time.

As can be seen from the above examples and comparative examples, the coating polyurethane resin prepared according to the method of the present invention has excellent bending resistance, water resistance, and water dispersion stability, so that the metal sheet, electrical parts, shoes, nylon fibers Or it can be used suitably as surface coating agent of various products, such as polyester fiber and glass fiber.

Claims (12)

In the manufacturing method of the aqueous polyurethane resin for coating, In the presence of a catalyst, a polyol, a diisocyanate, and a diol having a hydrophilic group, a diamine having a hydrophilic group, or a mixture thereof are reacted to prepare a prepolymer, which is neutralized with a neutralizing agent and water is added as a dispersion medium to prepare an aqueous product. Adding a chain extender to the water dispersion to perform a chain extension reaction to obtain a polyurethane water dispersion, Here, the NCO / OH ratio defined by (moles of diisocyanate) ÷ (moles of polyol + moles of hydrophilic group-containing diol) is 1.1 to 3.0, and the content of diols having hydrophilic groups, diamines having hydrophilic groups, or mixtures thereof A method for producing an aqueous polyurethane resin for coating, characterized in that from 1 to 10% by weight relative to the solids of the final aqueous polyurethane polymer. delete The method of claim 1, wherein the polyol is one or two or more mixtures selected from polyester polyols or polyether polyols having at least two hydroxyl groups at the terminal of the molecule prepared by the condensation reaction of dibasic acid and dihydric alcohol, the average molecular weight The 200 to 10,000. The dibasic acid is used by mixing at least one selected from adipic acid, azelaic acid, succinic acid, terephthalic acid, and isophthalic acid, wherein the dihydric alcohol is ethylene glycol, 1,3-propanediol, At least one selected from 1,4-butanediol, 1,6-hexanediol, neopentylglycol, 2-methylpropanediol, 1,4-cyclohexanedimethanol, and bisphenol A Way. The method of claim 1, wherein the diisocyanate is isophorone diisocyanate (IPDI), 1,6-hexamethylene diisocyanate (1,6-HDI), tetramethylxylene diisocyanate (1,3 or 1,4-TMXDI) And methylenebiscyclohexane diisocyanate (4,4-H ₁₂ MDI). According to claim 1, wherein the diol having a hydrophilic group is dimethylol propionic acid (DMPA), dimethylol butyric acid (DMBA) or a mixture thereof, the diamine having a hydrophilic group is selected from one or more compounds represented by the following formula (1) Characterized in that the method. Formula 1

In the above formula, R ₁ is an alkyl group having 2 to 10 carbon atoms, and R ₂ and R ₃ are the same or different hydrogen atoms or an alkyl group having 1 to 2 carbon atoms. The method of claim 1, wherein the neutralizing agent is trimethylamine, triethylamine, triisopropylamine, tributylamine, N, N-dimethyl cyclohexylamine, N, N-dimethylaniline, N, N-dimethyl aminoethanol and N Tertiary amines selected from the group consisting of methyl morpholine or inorganic bases selected from the group consisting of sodium hydroxide, potassium hydroxide and lithium hydroxide, the amount being 80 moles of diol and / or diamine moles having the total hydrophilic group used; It is -120 mol%, The method characterized by the above-mentioned. The chain extender of claim 1, wherein the chain extender consists of hydrazine, ethylene diamine, diethylene triamine, triethylene tetraamine, diaminohexane, isophorone diamine, dicyclohexylmethylene diamine, 1.6-hexamethylene diamine and piperazine. At least one selected from the group. The method of claim 1, wherein the prepolymer further comprises a step of dissolving in an at least one organic solvent selected from the group consisting of acetone, methyl ethyl ketone, isopropyl alcohol and ethanol before neutralizing with a neutralizing agent, and then neutralizing with a neutralizing agent. How to. An aqueous polyurethane resin for coating prepared by the method of any one of claims 1 and 3 to 9. A product in which the aqueous polyurethane resin for coating according to claim 10 is applied as a surface coating agent. 12. The product of claim 11, wherein the product is a metal plate, electrical component, shoe, nylon fiber, polyester fiber or glass fiber.