KR100341870B1 - Process for preparing aqueous polyurethane - Google Patents

Abstract

The present invention relates to a method of increasing the molecular weight and adhesion of the water-dispersed polyurethane through a chain extension method, polyester polyol, dimethylol propionic acid and aliphatic containing 30% by weight or more of the crystalline polyol having a melting point of 30 ℃ or more An isocyanate compound is reacted to prepare an isocyanate type prepolymer having a carboxyl terminal, and then the prepolymer is cooled and neutralized by addition of a carboxyl equivalent of a tertiary amine, followed by dispersion by addition of water and chain extension with a chain extender.

As such, when the molecular weight is increased through the chain extension method, it is possible to obtain an appropriate molecular weight or adhesive strength only by changing the addition amount of the chain extender. The obtained polyurethane is a water dispersion type, which has excellent safety, initial and state adhesion, heat resistance, and heat resistance. It can be used as an excellent adhesive.

Description

Process for preparing aqueous polyurethane

The present invention relates to a method for increasing the molecular weight and adhesion of the water-dispersed polyurethane through a chain extension process, and more specifically, to a prepolymer having a carboxyl group in the sock terminal of the polyurethane in a conventional manner. Prepare water-based polyurethane particles with various particle sizes according to the degree of neutralization by adding amines to them, and the molecular weight of the polyurethane particles and the polyurethane-urea-based water-based adhesive agent according to the degree of chain extension of the chain extender. A method of increasing the adhesion.

Polyurethane solvent-type adhesives have been widely used as adhesives until now, and have excellent heat resistance, oil resistance, solvent resistance, cold resistance, flexibility, and excellent adhesion to various materials. However, since it contains a large amount of solvents such as toluene, acetone, methyl ethyl ketone, cyclohexane, etc., it causes environmental pollution and cannot guarantee worker safety.

Therefore, efforts have been made to aqueousize hydrophobic polyurethanes, which include a method of introducing a hydrophilic group into a polyurethane skeleton to form a self-emulsifying resin and then dispersing it in water [Japanese Patent Laid-Open No. 4-328187, Japan]. Japanese Patent Application Laid-Open No. Hei 5-43642] and the like (For example, Japanese Patent Publication No. 39-5989, Japanese Patent Publication No. 45-10957), etc., forcibly dispersing the hydrophobic polyurethane using a large amount of emulsifier.

However, conventional water dispersion methods and resin manufacturing methods do not satisfy the molecular weight and adhesive strength of solvent-type products.

As a result of research efforts to solve the problems in producing a water-dispersed polyurethane in many aspects, it was found that the molecular weight and adhesion can be increased by improving the chain extension process after water dispersion, thereby completing the present invention.

More specifically, the present inventors have been researched to improve the adhesion through the molecular weight of the conventional water-dispersed polyurethane, as a result of neutralizing the polyurethane prepolymer obtained by reacting a polyol and aliphatic polyisocyanate and then reacting dimethylol propionic acid with a neutralizing agent. After dispersing in water and preparing dispersed particles having various particle sizes, the present invention was completed by examining the molecular weight and adhesive strength according to the degree of chain extension, and preparing the water-dispersed polyurethane-urea-based adhesive through the appropriate degree of chain extension. It was.

Accordingly, it is an object of the present invention to provide a method for producing an extended polyurethane dispersion having a good safety, excellent initial and state adhesion, heat resistance and water resistance, and more than the molecular weight of a solvent-based polyurethane product.

Such a method for producing a water-dispersed polyurethane of the present invention has a carboxyl end group by reacting a polyester polyol and dimethylol propionic acid containing 30% by weight or more of a crystalline polyol having a melting point of 30 ° C. or more with an aromatic polyisocyanate compound. After the isocyanate type polyurethane prepolymer is prepared, it is neutralized by adding a tertiary amine to it, followed by water dispersion for water dispersion, and chain extension by dropwise addition of a chain extender.

1 is a graph showing the molecular weight change according to the chain extension of Example 1 (-■-), Example 9 (-▲-), and Comparative Example 3 (-●-) of the present invention,

Figure 2 shows the amount of change in the residual NCO group of Example 1 (Fig. 2a) and Example 9 (Fig. 2b) of the present invention.

The present invention relates to a method for preparing a water-dispersed polyurethane in which the weight average molecular weight increases from 80,000 to 300,000 g / mol during the chain extension process by adjusting the size of the water-dispersible particles, and isocyanate having a carboxyl end group used in the present invention. The type polyurethane prepolymer is prepared by reacting a polyol, dimethylol propionic acid and aliphatic isocyanate mixture with a NCO / OH ratio of 1.1 to 3.0, preferably 1.2 to 2.5, according to a conventional polyurethane production method. At this time, if the NCO / OH ratio is less than 1.1, the physical properties are poor, and if it exceeds 3.0, the safety is lowered.

As the polyol used in preparing the polyurethane prepolymer of the present invention, a polyester polyol containing 30 wt% or more of a crystalline polyol having a melting point of 30 ° C. or more as a compound having at least two hydroxyl groups in the compound is used. The crystalline polyol is a polyol having a melting point of 30 ° C. or higher, specifically a polyester polyol having a molecular weight of 500 to 4000, and can be prepared from adipic acid and hexanediol and has a hydroxyl number of 38 (mg / KOH). / equivalent weight polyol).

As the aliphatic isocyanate mixture used in the present invention, two or more isocyanates are bonded directly or indirectly to an aliphatic chain such as isophorone diisocyanate, 1,6-hexamethylene diisocyanate or 4,4-dicyclomethane diisocyanate. Used compounds.

In the present invention, dimethylolpropionic acid is used in an amount of 6.0 to 14.0 parts by weight based on 100 parts by weight of the polyol in order to introduce a hydrophilic group. If the amount is less than 6.0 parts by weight, the stability of the water dispersion is lowered. If the amount is more than 14.0 parts by weight, the water resistance and the adhesive force are lowered. In using dimethylol propionic acid, 120-200 weight part of N-methyl- 2-pyrrolidone, methanol, and ethanol are added, dissolved, and used for 100 weight part of dimethylol propionic acids.

The method for preparing a polyurethane prepolymer using such a polyol, dimethylolpropionic acid and aliphatic isocyanate mixture is a conventional method. Specifically, the polyol and aliphatic isocyanate mixture are reacted at 70 to 90 ° C. for 100 to 150 minutes. Thereafter, dimethylolpropionic acid is added to the mixture to further react for 50 to 100 minutes to prepare a carboxyl terminal NCO-type polyurethane prepolymer.

The method for dispersing the polyurethane prepolymer thus prepared is first performed by neutralizing the prepolymer with a neutralizing agent, followed by dispersion by adding water with stirring, followed by chain extension by adding a chain extender.

At this time, a tertiary amine such as dimethylaminoethanol, N-methylmorpholine or triethylamine is used as the neutralizing agent, and its amount is about 80 to 120 equivalent% of the carboxyl equivalent in the polyurethane prepolymer, You can adjust the usage.

Diamines and diols can be used as the chain extender, specifically, compounds containing two primary or secondary amino groups and two hydroxyl groups are ethylenediamine, propylenediamine, butylenediamine, pentylenediamine, hexamethylenediamine, and ethylene. Diol, propylenediol, butylenediol, pentylenediol, hexamethylenediol selected from among them are used in combination.

The amount of the chain extender used depends on the ratio of NCO / OH, specifically 1.5 to 22.5 g.

Solid content concentration after water dispersion and chain extension is 25-50 weight%, and the polyurethane water dispersion excellent in stability and adhesive force is obtained.

The polyurethane water dispersion prepared as described above is used in one-part form, and may exhibit excellent adhesive properties not only by adhesion of wood, fiber, plastic leather, etc. by high temperature curing but also by low temperature curing.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited by the Examples.

Example 1

After reacting 120 g of polyester polyol (molecular weight 3000 g / mol, melting point 40-45 ° C.) of 38 hexanediol / adipic acid and 36.1 g of isophorone diisocyanate at 80 ° C. for 140 minutes , 12 g of dimethylol propionic acid was dissolved in 20 g of N-methyl-2-pyrrolidone, and then added and reacted for 80 minutes to prepare a carboxyl terminal NCO-type polyurethane prepolymer.

The prepared polyurethane prepolymer was cooled to 60 ° C. and neutralized by adding 9 g of triethylamine with rapid stirring. The neutralized prepolymer was dispersed for 20-30 minutes by the addition of water at a solid concentration of 40% by weight. Here, 3.9 g of hexamethylenediamine was dissolved in water and quantitatively added thereto to obtain a polyurethane-urea aqueous dispersion sample, and the molecular weight, residual NCO amount, and adhesive strength were examined.

Example 2

After reacting 120 g of polyester polyol (molecular weight 3000 g / mol, melting point 40-45 ° C.) of 38 hexanediol / adipic acid and 36.1 g of isophorone diisocyanate at 80 ° C. for 140 minutes , 12 g of dimethylol propionic acid was dissolved in 20 g of N-methyl-2-pyrrolidone, and then added and reacted for 80 minutes to prepare a carboxyl terminal NCO-type polyurethane prepolymer.

The prepared polyurethane prepolymer was cooled to 60 ° C. and neutralized by adding 9 g of triethylamine with rapid stirring. The neutralized prepolymer was dispersed for 20-30 minutes by the addition of water at a solid concentration of 40% by weight. 1.72 g of hexamethylenediamine was added dropwise thereto, dissolved in water, and quantitatively added thereto to obtain a polyurethane-urea aqueous dispersion.

Example 3

After reacting 120 g of polyester polyols (molecular weight: 3000 g / mol, melting point: 40 to 45 ° C.) of 38 hexanediol / adipic acid and 41.9 g of isophorone diisocyanate at 80 ° C. for 140 minutes, 12 g of dimethylol propionic acid was dissolved in 20 g of N-methyl-2-pyrrolidone, and then added and reacted for 80 minutes to prepare a carboxyl terminal NCO-type polyurethane prepolymer. The prepared polyurethane prepolymer was cooled to 60 ° C. and neutralized by adding 9 g of triethylamine with rapid stirring. The neutralized prepolymer was water-dispersed for 20-30 minutes with the addition of water at a solids concentration of 40% by weight. Here, 6.8 g of hexamethylenediamine was dissolved in water and quantitatively added thereto to obtain a polyurethane-urea aqueous dispersion.

Example 4

After reacting 120 g of polyester polyols (molecular weight 3000 g / mol, melting point 40-45 ° C.) of 38 hexanediol / adipic acid and 47.6 g of isophorone diisocyanate at 80 ° C. for 140 minutes, 12 g of dimethylol propionic acid was dissolved in 20 g of N-methyl-2-pyrrolidone, and then added and reacted for 80 minutes to prepare a carboxyl terminal NCO-type polyurethane prepolymer. The prepared polyurethane prepolymer was cooled to 60 ° C. and neutralized by adding 9 g of triethylamine with rapid stirring. The neutralized prepolymer was dispersed for 20-30 minutes by the addition of water at a solid concentration of 40% by weight. 9.86 g of hexamethylenediamine was dissolved in water and quantitatively added thereto to obtain a polyurethane-urea aqueous dispersion.

Example 5

After reacting 120 g of polyester polyols (molecular weight 3000 g / mol, melting point 40-45 ° C.) of 38 hexanediol / adipic acid and 59.1 g of isophorone diisocyanate at 80 ° C. for 140 minutes, 12 g of dimethylol propionic acid was dissolved in 20 g of N-methyl-2-pyrrolidone, and then added and reacted for 80 minutes to prepare a carboxyl terminal NCO-type polyurethane prepolymer. The prepared polyurethane prepolymer was cooled to 60 ° C. and neutralized by adding 9 g of triethylamine with rapid stirring. The neutralized prepolymer was dispersed for 20-30 minutes by the addition of water at a solid concentration of 40% by weight. After cooling to 25 ° C., 7.94 g of hexamethylenediamine was added dropwise thereto, dissolved in water, and quantitatively added thereto to obtain a polyurethane-urea aqueous dispersion.

Example 6

In the same manner as in Example 2, a neutralized prepolymer was prepared, and water was added at a solid concentration of 40% by weight to disperse water for 20 to 30 minutes. After cooling to 25 ° C., 1.72 g of hexamethylenediamine was added dropwise thereto, dissolved in water, and quantitatively added thereto to obtain a polyurethane-urea aqueous dispersion.

Example 7

In the same manner as in Example 3, a neutralized prepolymer was prepared, and water was added at a solid concentration of 40% by weight to disperse water for 20 to 30 minutes. After cooling to 25 ° C., 3.86 g of hexamethylenediamine was added dropwise thereto, dissolved in water, and quantitatively added thereto to obtain a polyurethane-urea aqueous dispersion.

Example 8

In the same manner as in Example 4, a neutralized prepolymer was prepared, and water was added at a solid concentration of 40% by weight to disperse water for 20 to 30 minutes. After cooling to 25 ° C., 5.31 g of hexamethylenediamine was added dropwise thereto, dissolved in water, and quantitatively added thereto to obtain a polyurethane-urea aqueous dispersion.

Example 9

Except for using 10.8g instead of 9g of triethylamine, the polyurethane-urea aqueous dispersion sample was collected in the same manner as in Example 1, and the molecular weight, residual NCO amount, and adhesion were examined.

Example 10

A polyurethane-urea water dispersion was prepared in the same manner as in Example 4, except that 36.0 g of 1,6-hexamethylene diisocyanate was used instead of isophorone diisocyanate.

Example 11

A polyurethane-urea water dispersion was prepared in the same manner as in Example 4, except that 56.2 g of 4,4-dicyclomethane diisocyanate was used instead of isophorone diisocyanate.

Comparative Example 1

After the crystalline number 38 of hexane diol / adipic polyester polyol piksan (molecular weight of 3000g / mol, melting point 40~45 ℃) 120g, isophorone diisocyanate, 33.2g of a hydroxyl group at room temperature and reacted for 140 minutes at 80 ℃ , 12 g of dimethylol propionic acid was dissolved in 20 g of N-methyl-2-pyrrolidone, and then added and reacted for 80 minutes to prepare a carboxyl terminal NCO-type polyurethane prepolymer.

The prepared polyurethane prepolymer was cooled to 60 ° C. and neutralized by adding 9 g of triethylamine with rapid stirring. The neutralized prepolymer was dispersed for 20-30 minutes by the addition of water at a solid concentration of 40% by weight. 1.17 g of hexamethylenediamine was added dropwise thereto, dissolved in water, and quantitatively added thereto to obtain a polyurethane-urea aqueous dispersion.

Comparative Example 2

0.5g of hexamethylenediamine was added dropwise, dissolved in water, and quantitatively added, and then the sample of polyurethane-urea dispersion was collected in the same manner as in Example 5, and the molecular weight, residual NCO amount, and adhesive strength were examined.

Comparative Example 3

Except for using 8.5g instead of 9g of triethylamine, the polyurethane-urea aqueous dispersion sample was collected in the same manner as in Example 1, and the molecular weight, residual NCO amount, and adhesion were examined.

Comparative Example 4

Except for using 7.8g instead of 9g of triethylamine, the polyurethane-urea aqueous dispersion sample was collected in the same manner as in Example 2, and the molecular weight, residual NCO amount and adhesion were examined.

Experimental Example 1

In Examples 2 to 11, Comparative Examples 1 to 4, and the products of other companies, particle size, initial adhesive strength, and weight average molecular weight were measured by the following method, and the results are shown in Tables 1 and 2 below.

-Initial Adhesion Measurement Method

The soft PVC specimens were cut to a size of 200 × 20 mm and dried by washing the surface with methyl ethyl ketone. The surface treatment agent for polyurethane adhesive was brushed once on the adhesive surface of the specimen and dried at 60 ° C. for 10 minutes.

An aqueous polyurethane adhesive was applied and heat-treated at 100 ° C. for 10 minutes, and then the adhesive surfaces were bonded and pressed by using a hand roller at a load of about 5 kg _f . After adhesion, heat treatment was performed at 100 ° C. for 5 minutes. After the heat-treated specimen was left at room temperature for 1 hour, the adhesive strength was measured by peeling at a tensile speed of 100 ± 0.5 mm / min using a universal tensile tester (Instron Model 4466). At this time, five or more test pieces were used for the same test.

-Molecular weight and molecular weight distribution

The molecular weight and the molecular weight distribution were measured by gel permeation chromatography (GPC, Waters). After drying, the dried sample was dissolved in 0.5% by mass of a tetrahydrofuran (THF) solvent, and then subjected to gel permeation chromatography at room temperature using a μ-styragel series (10 ³ Å pore size-HR 3-HR 4) column. Input. The flow rate of solvent THF was 1.0 mL / min, and the standard curve of the molecular weight with respect to the delay time was calibrated with the polymethylmethacrylate (PMMA) standard. The detector was RI detector (Waters 410). At this time, the molecular weight of PMMA used as a standard sample used for calibration is weight average molecular weight 3100, 12700, 91000, and 1577000.

Residual NCO detection

After preparing the water-dispersible polyurethane, in order to check the urethane bonds, each sample was applied to the KBr thinly and sufficiently dried, and then the bonding state was confirmed using FT-IR (Genesis Series of ATI Mattson).

Polyurethane Particle Size (nm) Weight average molecular weight (g / mol) Adhesive force (kgf / 2.0cm) Example 2 230.0 80451 7.64 3 276.4 121471 8.49 4 303.1 153460 9.95 5 319.8 259241 11.57 6 202.7 83411 8.09 7 239.4 137945 9.52 8 270.2 172932 10.23 10 298.4 82354 7.98 11 307.2 102463 8.25 Comparative example One 201.7 54588 5.98 2 284.5 76849 7.59 5 154.9 65108 8.70 Comparative Example 5: Bayer 52 of Bayer, Germany

division Example Comparative example One 9 3 4 Polyurethane Particle Size (nm) 230.0 90.2 291.7 405.3 Weight average molecular weight (g / mol) after adding 100% of the chain extender theoretical amount 78395 87934 73779 55714 Maximum weight average molecular weight (g / mol) during chain extender 80451 90162 76378 59130 Chain extender ratio (weight%) to theoretical amount injected up to the maximum molecular weight 44.0 57.1 30.8 10.2 Adhesive force (kg _f /2.0㎝) 7.64 9.11 7.01 5.12

Meanwhile, in preparing the water-dispersed polyurethanes according to Examples 1 and 9 and Comparative Example 3, the molecular weight change according to the chain extension was measured and the results are shown in FIG. 1.

In FIG. 1,-■-is Example 1,-▲-is Example 9, and-●-is a case of the comparative example 3. In FIG.

From this result, the result as shown in Table 2 can be confirmed.

In addition, in Example 1 and Example 9, the change amount of the residual NCO group for each manufacturing stage was measured, and it is shown in FIG. 2A is a case of Example 1, and FIG. 2B is a case of Example 9. FIG.

From the results of Figures 2a and 2b it can be seen that the amount of residual NCO groups according to the degree of chain extension, the amount of residual NCO immediately before the chain extension depends on the dispersed particle size.

Experimental Example 2

In order to examine the properties of the water-dispersed polyurethane prepared according to the above Examples and Comparative Examples as an adhesive, initial and state adhesive strength, heat resistance and water resistance were performed by the following method.

-Initial Adhesion Measurement Method

The soft PVC specimens were cut to a size of 200 × 20 mm and dried by washing the surface with methyl ethyl ketone. The surface treatment agent for polyurethane adhesive was brushed once on the adhesive surface of the specimen and dried at 60 ° C. for 10 minutes.

An aqueous polyurethane adhesive was applied and heat-treated at 100 ° C. for 10 minutes, and then the adhesive surfaces were bonded and pressed by using a hand roller at a load of about 5 kg _f . After adhesion, heat treatment was performed at 100 ° C. for 5 minutes. After the heat-treated specimen was left at room temperature for 1 hour, the adhesive strength was measured by peeling at a tensile speed of 100 ± 0.5 mm / min using a universal tensile tester (Instron Model 4466). At this time, five or more test pieces used for the same test were used.

-How to measure state adhesive force

The soft PVC specimens were cut to a size of 200 × 20 mm and dried by washing the surface with methyl ethyl ketone. The surface treatment agent for polyurethane adhesive was brushed once on the adhesive surface of the specimen and dried at 60 ° C. for 10 minutes.

An aqueous polyurethane adhesive was applied and heat-treated at 100 ° C. for 10 minutes, and then the adhesive surfaces were bonded and pressed by using a hand roller at a load of about 5 kg _f . After adhesion, heat treatment was performed at 100 ° C. for 5 minutes. After the heat-treated specimens were allowed to stand at room temperature for 48 hours, the adhesive strength was measured by peeling at a tensile speed of 100 ± 0.5 mm / min using a universal tensile tester (Instron Model 4466). At this time, five or more test pieces used for the same test were used.

-Heat and water resistance measurement method

The soft PVC specimens were cut to a size of 200 × 20 mm and dried by washing the surface with methyl ethyl ketone. Polyurethane adhesive surface treatment agent was brushed once on the adhesive surface of the specimen and dried at 60 ° C. for 10 minutes. Aqueous polyurethane adhesive was applied and heat-treated at 100 ° C. for 10 minutes, and then the adhesive surface was bonded to the hand roller. Was pressed using a load of about 5kg _f and bonded. After adhesion, heat treatment was performed at 100 ° C. for 5 minutes. After 48 hours of heat treatment, the specimens were left at room temperature for 48 hours and then left for 4 hours in water at 70 ° C. Then, the specimens were peeled at a tensile speed of 100 ± 0.5mm / min using a universal tensile tester (Instron Model 4466) to measure the adhesive strength. (ASTM D 1151-90). At this time, five or more test pieces used for the same test were used.

The results are shown in Table 3 below.

Initial Adhesion (kgf / 2.0cm) Adhesive force (kgf / 2.0cm) Heat and water resistant adhesive force (kgf / 2.0cm) Example 2 7.64 15.96 7.98 3 8.49 18.01 8.36 4 9.95 19.99 10.12 5 11.57 20.98 13.24 6 8.09 16.11 8.21 7 9.52 18.89 8.99 8 10.23 20.10 9.10 10 7.98 16.01 7.14 11 8.25 16.53 7.34 Comparative example One 5.98 8.57 6.01 2 7.59 12.90 6.07 5 8.70 16.84 8.42 Comparative Example 5: Bayer 52 of Bayer, Germany

As described in detail above, in the case of extending the chain of the polyurethane prepolymer through the chain extension according to the present invention, not only can produce a water-dispersible polyurethane having the desired molecular weight and adhesion, but also according to the present invention By using water that does not contain solvent when dispersing, it has the effect that processes such as vacuum distillation to remove solvent can be omitted.

Claims (8)

A polyisocyanate type prepolymer having a carboxyl terminal is prepared by reacting a polyester polyol, dimethylol propionic acid, and an aliphatic isocyanate compound containing 30 wt% or more of a crystalline polyol having a melting point of 30 ° C. or more. Cool the prepolymer and neutralize it by adding tertiary amine to the cooled prepolymer in accordance with the carboxyl equivalent. Dispersing the neutralized prepolymer by adding water, followed by chain extension of the prepolymer with a dropwise addition chain extender determined according to the ratio of NCO / OH dispersed by water to produce a water-dispersed polyurethane. The method of claim 1, Method for producing a water-dispersed polyurethane, characterized in that the crystalline polyol is a molecular weight of 500 to 4000 produced from adipic acid and hexanediol. The method of claim 1, The aliphatic isocyanate compound is a method for producing a water-dispersed polyurethane, characterized in that at least one selected from the group consisting of isophorone diisocyanate, 1,6-hexamethylene diisocyanate and 4,4-dicyclomethane diisocyanate is used. . delete The method of claim 1, Neutralization of the prepolymer is carried out by adding at least one tertiary amine selected from the group consisting of dimethylaminoethanol, N-methylmorpholine and triethylamine to 80-120 equivalent% of the equivalent of the polyurethane main chain terminal group carboxyl group. The manufacturing method of water-dispersed polyurethane made into. The method of claim 1, As the chain extender, at least one selected from the group consisting of ethylenediamine, propylenediamine, butylenediamine, pentylenediamine, hexamethylenediamine, ethylenediol, propylenediol, butylenediol, pentylenediol and hexamethylenediol Method for producing a water-dispersed polyurethane, characterized in that. The method of claim 1, A method of producing a water-dispersed polyurethane, characterized in that the amount of the chain extender is determined according to the ratio of NCO / OH. The method according to claim 1 or 7, A method for producing a water-dispersed polyurethane, characterized in that the amount of the chain extender is 1.5 to 22.5g.