JPH093126A - Aqueous dispersion of polyurethane resin - Google Patents

Abstract

(57) [Summary] [Purpose] To provide an aqueous dispersion of a polyurethane resin having excellent storage stability and excellent physical properties after drying. [Structure] A polyurethane resin (A) having an ionic functional group having an ionic functional group value of 0.25 to 1.8 (meq / g), and an ion having an ionic functional group value of 0.35 (meq / g) or less and (A) An aqueous dispersion of a polyurethane resin containing a polyurethane resin (B) having a smaller functional group value. [Effect] According to the present invention, it is possible to supply an aqueous dispersion of a polyurethane resin that is stable and has excellent water resistance and alkali resistance after drying.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an aqueous dispersion of a polyurethane resin having excellent storage stability. More specifically, it relates to a polyurethane aqueous dispersion which is used for coating metal, wood, paper, leather, glass, fibers, plastics, foams, concrete, etc. and has excellent water resistance, alkali resistance and hot water resistance after drying.

[0002]

2. Description of the Related Art In recent years, from the viewpoint of low pollution, resource saving, easy handling, and low risk of fire, the use of various polymers in water has been studied. Various water-based polymers have been put to practical use in the fields of paints, printing inks, adhesives, etc., and the same applies to polyurethane resins.
However, it is necessary to incorporate a hydrophilic functional group such as a carboxyl group into the resin in order to make it aqueous, and the excessive presence of these hydrophilic functional groups causes the physical properties of the coating film after drying, particularly water resistance and alkali resistance, There was a problem of reducing hot water resistance.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an aqueous dispersion of a polyurethane resin which has excellent storage stability and excellent physical properties after drying.

[0004]

Means for Solving the Problems That is, the present invention provides a polyurethane resin (A) having an ionic functional group having an ionic functional group of 0.25 to 1.8 (meq / g), and
Provided is an aqueous dispersion of a polyurethane resin containing a polyurethane resin (B) of 0.35 (meq / g) or less and smaller than the ionic functional group value of (A).

When the ionic functional group value of the polyurethane resin (A) is less than 0.25 (meq / g), it is difficult to make it aqueous after mixing with the polyurethane resin (B), and when it exceeds 1.8 (meq / g). Has poor water resistance and alkali resistance even when mixed with the polyurethane resin (B). Further, when the ionic functional group value of the polyurethane resin (B) exceeds 0.35 (meq / g), the water resistance and alkali resistance are poor.

Further, the ionic functional group values of the polyurethane resin (A) and the polyurethane resin (B) each satisfy the above-mentioned range, and the difference in the ionic functional group values of the two resins is
When it is 0.01 to 0.4 (meq / g), the resin (A) and the resin (B) are closely entangled with each other to form a stable composite resin emulsion. Therefore, it is possible to obtain an aqueous dispersion of a polyurethane resin that is particularly excellent in stability and has excellent properties after drying.

The polyurethane resin used in the present invention is
An active hydrogen compound such as a hydroxy compound or an amine compound, an organic polyisocyanate, and the polyurethane resin (A) are obtained by reacting an ionic functional group-containing compound such as a carboxyl group, and the production method is not particularly limited. .

As the hydroxy compound, water, low-molecular-weight glycols, low-molecular-weight polyols, and high-molecular-weight diols can be used, bisphenols such as bisphenol A and bisphenol F, bisphenol A and bisphenol F, and ethylene oxide and propion oxide. The glycols to which the alkylene oxide of is added can also be used.

As the low molecular weight glycols, ethylene glycol, diethylene glycol, triethylene glycol, butanediol, propanediol, 1,6-hexanediol, neopentyl glycol, cyclohexanedimethanol, acetylene glycol and 3,9-bis ( 1,1-
Dimethyl-2-hydroxyethyl) -2,2,8,10-tetraoxospiro [5,5] undecane and the like can be mentioned. Examples of the low molecular weight polyols include trimethylolpropane, triols such as glycerin, and tetraols such as pentaerythritol.

Examples of the high molecular weight diol include polyether diols and polyester diols. As polyether diols, tetrahydrofuran,
Or ethylene oxide, propylene oxide,
Polymers, copolymers or graft polymers of alkylene oxides such as butylene oxide, hexanediol, methylhexanediol, heptanediol,
Examples thereof include polyether glycols obtained by condensation of octanediol or a mixture thereof, and propoxylated or ethoxylated polyether glycols.

The polyester diols include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol,
Hexanediol, methyl-1,5-pentanediol, octanediol, cyclohexanediol, 2-ethyl-
Condensation reaction of saturated or unsaturated low molecular weight glycols such as 1,3-hexanediol, bisphenol A, diethylene glycol, triethylene glycol, dipropylene glycol and aliphatic or aromatic dibasic acid or aromatic dibasic acid ester The reaction product of the terminal hydroxyl group obtained by the ring-opening polymerization of the polyester diol obtained by the above or a cyclic ester compound such as ε-polycaprolactone can be used.

As the amine compound, ethylenediamine, trimethylenediamine, tetramethylenediamine,
Pentamethylenediamine, 1,7-diaminoheptane, 1,8-
Diaminooctane, xylylenediamine, 1,4'-diamino-3,3'-dimethyldicyclohexylmethane, 3,9-bis (3
-Aminopropyl) -2,4,8,10-diamines such as tetraoxyspiroundecane, triamines such as triaminopropane, terminal amino groups obtained by the reaction of these with an organic polyisocyanate compound or a polyepoxy compound, or Reaction products of hydroxyl groups can be used.

Further, if necessary, a monoamine compound may be used as a molecular weight modifier. Examples of monoamine compounds include dialkylamines such as di-n-butylamine, monoethanolamine, diethanolamine, 2-amino-2-methyl-1-propanol, tri (hydroxymethyl) aminomethane, 2-amino-2- Use amines having hydroxyl groups such as ethyl-1,3-propanediol, alkylhydrazines such as monomethylhydrazine, 1,1-dimethylhydrazine and benzylhydrazine, and hydrazides such as form hydrazide, acetohydrazide and lauric acid hydrazide. be able to.

When the aqueous dispersion of the polyurethane resin of the present invention is used in ink or the like, a polyhydrazine compound may be used in order to impart adhesion to a substrate or the like. Specifically, oxalic acid dihydrazide, malonic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide, hexadecane dihydrazide, eicosane diacid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, dihydrazide dihydrazide, maleic acid. , Phthalic acid dihydrazide, carbonic acid dihydrazide, carbodihydrazide, thiocarbodihydrazide, 4,4′-oxybisbenzenesulfonyl hydrazide, polyacrylic acid hydrazide and the like.

Examples of the ionic functional group-containing compound include a carboxyl group-containing compound, and specific examples thereof include dimethylolalkanoic acid such as dimethylolpropionic acid, dimethylolbutyric acid, and dimethylolvaleric acid, diaminocarboxylic acid, and low-molecular glycol. And a carboxyl group-containing polyester polyol obtained by an addition / condensation reaction of an aliphatic or aromatic polybasic acid anhydride with dimethylolalkanoic acid and a lactone as an initiator and a lactone as an initiator. .

Examples of the ionic functional group other than the carboxyl group include a quaternary ammonium group, a tertiary amino group, a sulfonate group, a sulfonic acid group, a sulfonium group, a phosphinic acid group and a sulfate ester group. Specific examples of compounds containing these ionic functional groups include amino acids, aminosulfonic acids and their oxyalkylated products and polyesterified products, sodium diaminobenzenesulfonate, glycerin monophosphate disodium salt, Examples thereof include sodium hydroxyethyl phosphonate, sodium dimethylol phosphinate, N-methyl ethanolamine, and polyester polyol having a sodium 5-sulfoisophthalate unit.

Further, in addition to the ionic functional group-containing component, a polyoxyethylene unit may be contained as a hydrophilic component. For example, conventionally known polyethylene glycol, polyethylene glycol-polypropylene glycol copolymer, JP-A-63- The diisocyanate having a polyoxyethylene unit in the side chain disclosed in Japanese Patent No. 305119 can be used.

As the organic polyisocyanate, tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, 1,5-naphthalene diisocyanate, isophorone diisocyanate, dimeryl diisocyanate, hydrogenated tolylene diisocyanate, bis -Chloromethyl-diphenylmethane-diisocyanate, 2,6-
Diisocyanates such as diisocyanate-benzyl chloride, or both-end isocyanate adducts of these with glycols or diamines, or a mixture thereof are included, and if necessary, triphenylmethane triisocyanate, polymethylene polyphenyl isocyanate, etc. Trifunctional or higher polyisocyanates can also be used as a mixture thereof. In addition, a commercially available polyisocyanate adduct such as "Desmodur series" manufactured by Bayer can also be used. Further, if necessary, monoisocyanates may be used as a molecular weight modifier.

In order to synthesize the polyurethane resin used in the present invention, an active hydrogen compound such as a hydroxy compound or an amine compound, an organic polyisocyanate, and a polyurethane resin (A) containing an ionic functional group-containing compound such as a carboxyl group. , Room temperature according to a conventionally known method
The reaction is carried out at 140 ° C, preferably 40-100 ° C. That is, a one-shot method in which these compounds are batch-charged to react with each other or a terminal isocyanate prepolymer is generated, and then a high molecular weight is obtained by a chain extender and / or a terminal terminator
The reaction is carried out by the prepolymer method of controlling the molecular weight. The latter method is particularly preferable.

In the prepolymer method, the ratio of isocyanate groups to active hydrogen during the preparation of the terminal isocyanate prepolymer is appropriately in the range of about 1.01 to 3.00: 1, preferably 1.03 to 2.50: 1. Further, when preparing the terminal isocyanate prepolymer, if necessary, a conventionally known urethane-forming catalyst, such as dibutyltin dilaurate, tin octylate, triethylamine, N, N-dimethylbenzylamine, sodium hydroxide, diethylzinc tetra (n- Butoxy) Titanium or the like can be used.

Further, although the prepolymer can be prepared in the absence of solvent, it is also possible to use an organic solvent which is inert to isocyanate groups in order to make the reaction uniform and adjust the viscosity. Specifically, acetone, methyl ethyl ketone, ethyl acetate, dioxane, acetonitrile, tetrahydrafuran, diglyme, dimethyl sulfoxide, N-
Methylpyrrolidone and the like can be mentioned, and these can be used alone or as a mixed system. Among these, those which can be easily removed in the solvent removal step are preferable.

In the chain extension / termination reaction following the preparation of the prepolymer, a solution obtained by diluting the chain extender and / or the terminator with an organic solvent inert to the isocyanate group is added to the prepolymer. The prepolymer can be added dropwise to the reaction, or conversely, the prepolymer can be added dropwise to the solution of the chain extender and / or the end stopper to react. The amount of the chain extender and / or the end terminator used is preferably an amount of 0.3 to 1.9 active hydrogen per one free isocyanate group in the prepolymer. Outside this range, adverse effects such as storage stability and film strength reduction of the resulting aqueous dispersion and discoloration are observed. The chain extension reaction is performed at room temperature ~ depending on the reactivity of active hydrogen with isocyanate.
It can be performed in the range of 95 ° C.

The molecular weights of resin (A) and resin (B) are
Both have a weight average molecular weight of 7,000 to 200,000, and even 20000.
The range of up to 50,000 is preferred. If the molecular weight is less than 7,000, the water resistance after drying is poor, and if it exceeds 200,000,
It becomes difficult to prepare an aqueous dispersion. The content ratio of the resin (A) and the resin (B) is preferably 10/90 to 90/10, more preferably 30/70 to 70/30 in terms of solid content ratio.

The method of blending the resin (A) and the resin (B) and the aqueous dispersion method are not well known and conventionally specified.
For example, (1) a solvent solution of resin (A) and resin (B) may be mixed and neutralized with an appropriate counterion, and then water may be added, or (2) each of them may be neutralized and hydrogenated. You may mix what was done. However, because of the entanglement of resins, (1)
Is preferred. The obtained aqueous dispersion of the polyurethane resin can be used as it is, but it is common to employ a step of azeotropically removing the organic solvent together with water by heating, depressurizing or the like.

The basic compound used for ionizing an ionic functional group such as a carboxyl group is ammonia, monoethylamine, diethylamine, trimethylamine, triethylamine, triisopropylamine, tributylamine, triethanolamine, diethylethanolamine, monoethanol. Amine, dimethylethanolamine, diethylethanolamine, morpholine,
Examples thereof include organic amines such as N-methylmorpholine and 2-amino-2-ethyl-1-propanol, and inorganic alkalis such as sodium hydroxide and potassium hydroxide, which may be used alone or in combination of two or more. Among these, in order to improve the water resistance after drying, those which are water-soluble and have high volatility that is easily dissociated by heat are preferable, and ammonia, trimethylamine and triethylamine are particularly preferable.

By adding an ordinary crosslinking agent to the aqueous dispersion of the polyurethane resin of the present invention, a cured coating film having further excellent film strength and chemical resistance can be formed. For example, when the ionic functional group of the polyurethane resin (A) is a carboxyl group, a polyaziridine compound,
Polyepoxy compounds, polycarbodiimide compounds, metal chelate compounds, polyoxazoline compounds, polyisocyanates, blocked polyisocyanates, partially or fully etherified amino resins and the like can be used as the crosslinking agent. These crosslinking reactions can be carried out at room temperature, or can be accelerated by heating or addition of a known reaction catalyst.

When these curing agent components are added at the mixing stage of the resin (A) and the resin (B) and then neutralization and phase inversion are carried out, the curing agent components are ubiquitous in the emulsion and the carboxyl group is present. Because the groups are oriented outside the emulsion,
The resulting aqueous dispersion is stable for a long period of time and exhibits excellent water resistance after drying.

In particular, in the system in which the alicyclic epoxy-containing compound is added to the aqueous dispersion of the polyurethane resin of the present invention in which the ionic functional group of the polyurethane resin (A) is a carboxyl group, the dispersion is excellent for a long period of time. The stability is maintained, and at the same time, the water resistance and alkali resistance of the coating film can be further improved. Specific examples of the alicyclic epoxy-containing compound include "UVR6110" and "UVR6128" manufactured by UNION CARBIDE.
, A diepoxide such as “Celoxide 2080” manufactured by Daicel, and a polyepoxide such as “Epolite GT-300” and “Epolite GT-400” manufactured by Daicel.

The amount of the alicyclic epoxy-containing compound added is preferably epoxy group (eq) / carboxyl group (eq) = 0.5 to 1.5. If it is less than 0.5, a large amount of hydrophilic carboxyl groups remain in the dry film, so the addition effect is not sufficient, and if it exceeds 1.5, a low molecular weight alicyclic epoxy-containing compound remains and the boiling performance etc. deteriorates. .

[0030]

The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited thereto. In the examples, "parts" means "parts by weight",
"%" Represents "% by weight", respectively.

Synthesis Example 1 Polytetramethyl ether having an average molecular weight (hereinafter referred to as Mw) of 3000 while introducing nitrogen gas in a reactor equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen gas inlet tube. Glycol 71.75 parts, 2,2-dimethylolpropionic acid 14.35 parts, neopentyl glycol
0.60 parts of isophorone diisocyanate and 48.60 parts of isophorone diisocyanate are reacted in 106.05 parts of methyl ethyl ketone at 80 ° C. for 4 hours to obtain a terminal isocyanate prepolymer, and then cooled to 40 ° C., and then 52.55 parts of methyl ethyl ketone is added to prepare a solvent solution of the terminal isocyanate prepolymer. Obtained. next,
Isophorone diamine 11.72 parts, methyl ethyl ketone 90.
To a mixture of 04 parts and 63.04 parts of water, 80% (235.12 parts) of the amount of the solvent solution of the terminal isocyanate prepolymer obtained was gradually added at room temperature and reacted at 60 ° C for 3 hours to obtain a polyurethane resin. To obtain a solvent solution a.

(Synthesis Example 2) A solvent solution b of a polyurethane resin was obtained from the following raw materials in the same manner as in Synthesis Example 1.・ Polytetramethyl ether glycol (Mw3000) 72.15 parts ・ Neopentyl glycol 10.75 parts ・ 2,2-dimethylolpropionic acid 3.45 parts ・ Isophorone diisocyanate 48.90 parts ・ Methyl ethyl ketone 106.05 parts ・ Methyl ethyl ketone 52 .55 parts-isophoronediamine 11.80 parts-methyl ethyl ketone 90.04 parts-water 63.04 parts

(Synthesis Example 3) A solvent solution c of a polyurethane resin was obtained from the following raw materials in the same manner as in Synthesis Example 1.・ Polytetramethyl ether glycol (Mw3000) 112.15 parts ・ Neopentyl glycol 3.60 parts ・ 2,2-dimethylolpropionic acid 1.95 parts ・ Isophorone diisocyanate 25.85 parts ・ Methyl ethyl ketone 106.05 parts ・ Methyl ethyl ketone 52 .55 parts-Isophorone diamine 5.16 parts-Methyl ethyl ketone 91.39 parts-Water 63.04 parts

(Synthesis Example 4) A solvent solution d of a polyurethane resin was obtained from the following raw materials in the same manner as in Synthesis Example 1.・ Polytetramethyl ether glycol (Mw3000) 112.75 parts ・ Neopentyl glycol 4.80 parts ・ Isophorone diisocyanate 26.00 parts ・ Methyl ethyl ketone 106.05 parts ・ Methyl ethyl ketone 52.55 parts ・ Isophorone diamine 5.16 parts ・ Methyl ethyl ketone 91 .39 parts ・ Water 63.04 parts

Table 1 shows the properties of the solvent solutions of the polyurethane resins obtained in Synthesis Examples 1 to 4. The molecular weight was measured by gel filtration chromatography in terms of polystyrene using a refractive index detector.

[0036]

[Table 1]

(Example 1) 47.8 parts of a solvent solution a of polyurethane resin and 47.6 parts of a solvent solution c of polyurethane resin were mixed, 2.51 parts of 28% ammonia water was added, and 52.42 parts of water was gradually added while mixing at room temperature. After the total amount of methyl ethyl ketone was distilled off at 50 ° C under reduced pressure, water was added to adjust the solid content, and the aqueous dispersion A of polyurethane resin having a solid content of 28.1%, a viscosity of 13.9 cps. And a particle size of 181.6 nm was added. Obtained. The particle size was measured with a light scattering photometer.

Example 2 Polyurethane resin solvent solution a 47.8 parts, Polyurethane resin solvent solution d 47.8 parts, 28%
Aqueous dispersion B of polyurethane resin was obtained in the same manner as in Example 1 using 2.01 parts of ammonia water and 53.05 parts of water.

Example 3 Polyurethane resin solvent solution b 47.8 parts, Polyurethane resin solvent solution c 47.6 parts, 28%
Aqueous dispersion C of polyurethane resin was obtained in the same manner as in Example 1 using 2.01 parts of ammonia water and 52.92 parts of water.

Example 4 Polyurethane resin solvent solution b 47.8 parts, Polyurethane resin solvent solution d 47.8 parts, 28%
Aqueous dispersion D of polyurethane resin was obtained in the same manner as in Example 1 using 1.50 parts of ammonia water and 53.56 parts of water.

Example 5 47.8 parts of a solvent solution b of a polyurethane resin and 47.6 parts of a solvent solution c of a polyurethane resin were used, and further an alicyclic epoxy (“UVR” manufactured by UCC) was used.
6110 ″) 0.85 parts were added and mixed, and then 2.01 parts of 28% ammonia water and 54.90 parts of water were added to obtain an aqueous dispersion E of a polyurethane resin in the same manner as in Example 1.

Comparative Example 1 4.05 parts of ammonia was added to 95.5 parts of a solvent solution a of polyurethane resin and mixed, and 50.89 parts of water was gradually added while mixing at room temperature, followed by the same method as in Example 1. Conversion was performed to obtain an aqueous dispersion F of polyurethane resin. However, this was an aqueous solution rather than an aqueous dispersion of resin.

Comparative Example 2 3.01 parts of ammonia was added to and mixed with 95.5 parts of a solvent solution b of a polyurethane resin, and 51.89 parts of water was gradually added while mixing at room temperature, and then the mixture was mixed in the same manner as in Example 1. After conversion, an aqueous dispersion G of polyurethane resin was obtained.

(Comparative Example 3) 0.54 parts of ammonia was added to 94.34 parts of a solvent solution c of polyurethane resin c and mixed, and 54.60 parts of water was gradually added while mixing at room temperature, followed by phase conversion in the same manner as in Example 1. However, gelation occurred and phase inversion was impossible.

(Comparative Example 4) 95.24 parts of a solvent solution d of polyurethane resin was gradually added while mixing 54.90 parts of water at room temperature, and then phase conversion was carried out in the same manner as in Example 1 except that gelation and conversion occurred. The phase was impossible.

Table 2 shows the results of evaluation of the properties and alkali resistance of the aqueous dispersions of the polyurethane resins obtained in Examples 1 to 5 and Comparative Examples 1 and 2. The alkali resistance is 40 mm in diameter for the obtained polyurethane resin aqueous dispersion.
What was poured into a Teflon container having a diameter of φ and a depth of 2 mm and dried at 40 ° C. for 3 days was dipped in a 0.2% NaOH aqueous solution at 25 ° C. for 2 days, and evaluated by two items of whitening degree and dissolution rate.

(1) Degree of Whitening The degree of whitening due to alkali immersion was visually observed.
The evaluation criteria are as follows. A: No cloudiness occurs. ○: A slight whiteness is generated. Δ: There is some transparency. X: Cloudy. (2) Elution rate After washing the resin after immersion in alkali twice with distilled water, 1
It was dried in an oven at 50 ° C. for 1 hour and weighed. The difference between this weight and the weight before dipping was divided by the weight before dipping and multiplied by 100 to calculate the dissolution rate.

[0048]

[Table 2] * 1: Particle size cannot be measured

[0049]

EFFECTS OF THE INVENTION According to the present invention, it is possible to supply an aqueous dispersion of a polyurethane resin which is stable and has excellent water resistance and alkali resistance after drying.

Claims (4)

[Claims] 1. A polyurethane resin (A) having an ionic functional group having an ionic functional group value of 0.25 to 1.8 (meq / g), and an ionic functional group value of 0.35 (meq / g) or less and (A). An aqueous dispersion of a polyurethane resin containing a polyurethane resin (B) having a smaller ionic functional group value. 2. The aqueous dispersion of polyurethane resin according to claim 1, wherein the ionic functional group of the polyurethane resin (A) is a carboxyl group. 3. The aqueous dispersion of polyurethane resin according to claim 1, wherein the difference in ionic functional group value between the polyurethane resin (A) and (B) is 0.01 to 0.4 (meq / g). 4. A compound containing an alicyclic epoxy-containing compound.
An aqueous dispersion of the described polyurethane resin.