JP2000169701A - Preparation of polyurethane resin aqueous dispersion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a preparation process of a carboxylate-type polyester polyurethane resin aqueous dispersion having an improved resistance to hydrolysis. SOLUTION: In the preparation process of a carboxylate-type polyester polyurethane resin aqueous dispersion using an organic polyisocyanate (a), a polyester polyol (b), a hydroxycarboxylic acid (c) and a neutralizing agent (d) comprising a tertiary monoamine as essential components, the neutralizing agent (d) is used in an amount of from 1.01 to 2 equiv. per 1 equiv. carboxyl group in the polyurethane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an aqueous polyurethane resin dispersion. More specifically, the present invention relates to a method for producing a carboxylate-type polyester-based polyurethane resin aqueous dispersion having improved hydrolysis resistance when present as an aqueous solution or aqueous dispersion.

[0002]

2. Description of the Related Art Heretofore, a method for producing an aqueous dispersion of a carboxylate-type polyester-based polyurethane resin has been to prepare a carboxyl group-containing polyurethane having a polyester chain in the main chain with a basic compound having less than 1 equivalent per equivalent of a carboxyl group. A method of neutralizing and dissolving or dispersing in an aqueous medium is generally used (for example, Japanese Patent Publication No. 42-24192).
And Japanese Patent Publication No. 43-9076).

[0003]

However, such an aqueous dispersion of a carboxylate type polyester-based polyurethane resin having a polyester chain in the main chain has been known from the beginning when stored in an aqueous solution or an aqueous dispersion for a long period of time. The existing free carboxyl groups or free carboxyl groups by-produced at the initial stage of hydrolysis of the polyester chains act as hydrolysis accelerators for the polyester chains, and the polyester chains of the polyurethane undergo hydrolysis degradation over time, resulting in resin There is a problem that physical properties are deteriorated. Such a phenomenon is particularly remarkable when the polyester chain is derived from the condensed polyester polyol and when the neutralizing agent is an organic amine. An effective hydrolysis-resistant agent or method for preventing this hydrolysis degradation has not yet been found.

[0004]

Means for Solving the Problems In view of the above problems, the present inventors have conducted intensive studies on a method for producing an aqueous dispersion of a carboxylate type polyester-based polyurethane resin having improved hydrolysis resistance. On the other hand, it has been found that the hydrolysis resistance is remarkably improved by using a specific excess amount of a neutralizing agent to suppress the generation of free carboxyl groups that promote hydrolysis, and arrived at the present invention. That is, the present invention provides a carboxylate type polyester system using a neutralizing agent (d) comprising an organic polyisocyanate (a), a polyester polyol (b), a hydroxycarboxylic acid (c) and a tertiary monoamine as essential components. In a method for producing an aqueous polyurethane resin dispersion, 1.01 to 1.0 equivalent of carboxyl group in polyurethane.
A method for producing an aqueous dispersion of a polyester-based polyurethane resin, which comprises using 2 equivalents of (d).

In the present invention, the organic polyisocyanate (a) constituting the polyurethane has a carbon number (NC).
2 to 12 aliphatic diisocyanates [for example, hexamethylene diisocyanate, excluding carbon in the O group;
(HDI), 2,2,4-trimethylhexane diisocyanate, lysine diisocyanate, etc.];
8 alicyclic diisocyanates [eg, 1,4-cyclohexane diisocyanate (CDI), isophorone diisocyanate (IPDI), 4,4′-dicyclohexylmethane diisocyanate (hydrogenated MDI), methylcyclohexane diisocyanate, isopropylidene dicyclohexyl-4,4 ′ Diisocyanate, 1,3-diisocyanatomethylcyclohexane (hydrogenated XDI), adamantane dissocyanate, etc.]; aliphatic diisocyanate having an aromatic ring [for example, xylylene diisocyanate (XDI), α, α, α ′, α ′ -Tetramethylxylylene diisocyanate (TMXDI) etc.];
To 20 aromatic polyisocyanates [e.g., 1,4-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate (TDI), diphenylmethane-2,4'- or 4,4'-diisocyanate (MD
I), naphthalene-1,5-diisocyanate, 3,
3'-dimethyldiphenylmethane-4,4'-diisocyanate, o-tolidine diisocyanate, crude TD
I, polyphenylmethane polyisocyanate (crude MD
I) etc.]; and mixtures of two or more of these. Of these, preferred are TDI, MDI, H
DI, IPDI, hydrogenated MDI and TMXDI.

As the polyester polyol (b),
For example, dicarboxylic acids [aliphatic dicarboxylic acids having 4 to 12 carbon atoms (succinic acid, adipic acid, sebacic acid, glutaric acid, azelaic acid, etc.), aromatic dicarboxylic acids having 8 to 16 carbon atoms (isophthalic acid, terephthalic acid, etc.) And ester-forming derivatives thereof (anhydrides, lower alkyl esters (methyl esters, etc.)) and low molecular weight glycols having 2 to 12 carbon atoms (ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexane). Poly (ethylene adipate) diol, poly (butylene adipate) diol, specifically poly (ethylene adipate) diol, specifically poly (ethylene adipate) diol , Poly (hexamethylene adipate) diol, poly (neopentyl) Jipeto) diol, poly (ethylene / butylene adipate) diol, poly (neopentyl / hexyl adipate) diol, poly (3
-Methylpentyl adipate) diol, poly (butylene isophthalate) diol; polylactone polyol [eg, polycaprolactone diol, poly-3-methylvalerolactone diol, etc.]; polycarbonate polyol [eg, polyhexamethylene carbonate diol, etc.]. . Of these, polyester diols obtained by a polycondensation reaction of a glycol component comprising a branched alkanediol having 5 to 10 carbon atoms and a dicarboxylic acid component are preferred. The number average molecular weight of the polyester polyol (b) is usually 500 to 5,000,
Preferably it is 1000-3000.

The hydroxycarboxylic acid (c) is a component used for introducing an anionic hydrophilic group for dispersing the polyester-based polyurethane in water. Specific examples of the (c) include lactic acid and the like. And dihydroxycarboxylic acids such as α, α-dimethylolacetic acid, α, α-dimethylolpropionic acid, and α, α-dimethylolbutyric acid. Of these, preferred are dihydroxycarboxylic acids, and particularly preferred are α, α-dimethylolpropionic acid and α, α-dimethylolbutyric acid.

[0008] Carboxyl groups (-C
OOH) is usually 0.1% based on the weight of the polyurethane.
It is 3 to 6% by weight, preferably 0.4 to 5% by weight. If the amount of the carboxyl group is less than 0.3% by weight, a stable aqueous dispersion cannot be obtained, and if it exceeds 6% by weight, the water resistance of the formed resin film tends to decrease.

As a component of the polyurethane, a chain extender and / or a chain terminator other than water can be used together with the above (a), (b) and (c) if necessary. Examples of the chain extender include diamines having 2 to 10 carbon atoms (eg, ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, toluenediamine, etc.); hydrazine or its derivatives (eg, dibasic dihydrazide, eg, adipic dihydrazide); Polyhydric alcohols of formulas 2 to 15 [dihydric alcohols (eg, ethylene glycol, propylene glycol, neopentyl glycol, 1,4-butanediol, diethylene glycol, etc.), trihydric alcohols (eg, glycerin, trimethylolpropane, etc.), and the like Alkylene oxide (ethylene oxide and / or propylene oxide) low-molar adduct (molecular weight of less than 500)]. Examples of the chain terminator include monoalcohols having 1 to 8 carbon atoms (methanol, ethanol, isopropanol, cellosolves, carbitols, etc.) and monoamines having 1 to 10 carbon atoms (monomethylamine, monoethylamine, monobutylamine, dibutylamine) , Monooctylamine, monoethanolamine, diethanolamine, etc.).

The tertiary monoamine constituting the neutralizing agent (d) used for neutralizing the carboxyl groups of the polyurethane includes tertiary monoamines having 3 to 12 or more carbon atoms, such as aliphatic tertiary monoamines. (Trimethylamine, triethylamine, triethanolamine, N-methyldiethanolamine, N, N-dimethylethanolamine, etc.); heterocyclic tertiary monoamines (N-methylpiperidine, N-methylmorpholine, etc.); unsaturated cyclic tertiary amine Tertiary monoamines (N-methylpyridine, N-methylquinoline, etc.); aliphatic tertiary monoamines containing aromatic rings (benzyldimethylamine, α-methylbenzyldimethylamine, etc.); aromatic tertiary monoamines (N-dimethylaniline, etc.) ) And combinations of two or more of these. Of these, preferred are aliphatic tertiary monoamines, and particularly preferred is triethylamine.

To neutralize the carboxyl groups of the polyurethane, an extension reaction (for example, 0.6 per equivalent of carboxyl groups) is carried out.
(D) in which no free isocyanate groups remain after neutralization with 0.95 equivalents of a tertiary monoamine and dissolution or dispersion in water to cause chain extension reaction. Primary or secondary monoamines having 0 to 10 or more carbon atoms may be used. Examples of such amines include ammonia, monoethanolamine, diethanolamine, diisopropanolamine, dimethylamine, diethylamine, dibutylamine, monooctylamine, 2-methyl-2-aminopropanolamine, pyridine, morpholine and the like. Combinations of more than one species may be mentioned.

The amount of (d) used in the present invention is usually 1.01 per equivalent of carboxyl group in the polyurethane.
To 2 equivalents, preferably 1.05 to 1.5 equivalents.
(D) If the amount is less than 1.01 equivalent, the effect of inhibiting hydrolysis is insufficient, and if it exceeds 2 equivalents, it becomes strongly alkaline and hydrolysis is accelerated, which is not preferable.

The aqueous polyurethane resin dispersion (including those apparently uniformly dissolved in water) according to the present invention is dissolved or dispersed in water after or while neutralizing the carboxyl group-containing polyurethane with (d). However, at this time, it is not necessary to use the required amount of (d) all at once. For example, as described above, a part of (d) (for example, 0.6 to 0.95 equivalent per equivalent of carboxyl group) After neutralizing the carboxyl group by using and dissolving or dispersing the polyurethane in water to extend the chain if necessary, the remaining (d)
May be added in a later step. When the step of producing the aqueous dispersion includes a step of distilling an organic solvent, this method is preferably employed.

The method for producing the polyurethane itself in the present invention may be an ordinary method, and is not particularly limited. Examples thereof include the following methods. Organic solvents containing no active hydrogen-containing group in the molecule (acetone, methyl ethyl ketone, tetrahydrofuran, N, N-
Dimethylformamide) or in the absence or presence of
The active hydrogen component consisting of (a) and (b) and (c) is mixed with an isocyanate (NC0) group and an active hydrogen-containing group at an equivalent ratio (NCO / active hydrogen-containing group) of usually 1.0.
In the range of 5 to 2.0, preferably 1.1 to 1.6, by a one-shot method or a multi-stage method, usually 20 ° C to 150 ° C,
The reaction is preferably carried out at 60 ° C to 110 ° C to form a terminal NCO.
A group-containing urethane prepolymer, which is usually neutralized at 10 ° C. to 60 ° C. after or while neutralizing the prepolymer with (d).
C., preferably at 20.degree. C. to 40.degree. C., if necessary, mixed with water containing a chain extender and / or a chain terminator to carry out an emulsification / chain extension reaction until the NCO group disappears. how to. (A) and (b) in the presence or absence of an organic solvent
And an active hydrogen component consisting of (c) and an NCO / active hydrogen-containing group equivalent ratio in the range of 0.5 to 0.99 by a one-shot method or a multi-step method, and a urethane polymer containing no terminal NCO group. And neutralizing it with (d) or mixing it with water while neutralizing, and optionally distilling off the organic solvent. (A) and (b) in the presence or absence of an organic solvent
With an active hydrogen component comprising an NCO / active hydrogen-containing group equivalent ratio in the range of 2.0 to 1.3 by a one-shot method or a multi-stage method to obtain a urethane polymer containing a terminal NCO group. ) Was neutralized with (d) and NCO /
A method in which an active hydrogen-containing group equivalent ratio is reacted in a range of 1.5 to 1.0, mixed with water, and, if necessary, an organic solvent is distilled off.

The aqueous dispersion of a polyester-based polyurethane resin obtained by the method of the present invention has good hydrolysis resistance and excellent long-term storage stability. Therefore, for example, various aqueous dispersions such as water-based paints, printing inks, adhesives and fiber treatment agents can be used. It can be suitably used for industrial applications.

[0016]

EXAMPLES The present invention will be further described with reference to the following examples, but the present invention is not limited to these examples. In the following, "parts" indicates parts by weight and "%" indicates% by weight.

Example 1 Poly (3) was placed in a closed reaction vessel equipped with a thermometer and a stirrer.
-Methylpentyl adipate) diol (number average molecular weight 2000) 175 parts, α, α-dimethylolpropionic acid (DMPA) 28.7 parts, IPDI 118 parts and acetone 214 parts were charged, and the reaction system was replaced with nitrogen gas. The mixture was reacted at 80 ° C. for 6 hours with stirring to obtain an NCO-terminated urethane prepolymer having a free isocyanate group content (hereinafter referred to as NCO content) of 3.6%. The obtained acetone solution was cooled to 40 ° C. and triethylamine was added.
7 parts (1.05 equivalent / carboxyl group) were added. Next, a solution prepared by dissolving 6.4 parts of di-n-butylamine in 650 parts of water was added to the acetone solution, and an emulsification and chain extension reaction was performed. To obtain 1000 parts (A1) of an aqueous urethane resin dispersion having a solid content of 35% and a viscosity of 370 cP / 25 ° C.

Example 2 1,4- was placed in a closed reaction vessel equipped with a thermometer and a stirrer.
Butane adipate diol (number average molecular weight 2000) 2
After 16 parts, 20.5 parts of DMPA, 107 parts of TDI and 230 parts of acetone were charged and the reaction system was replaced with nitrogen gas, the mixture was reacted at 80 ° C. for 6 hours with stirring, and the NCO% was 5.2%. A terminal urethane prepolymer was obtained. The obtained acetone solution was cooled to 40 ° C., and 21.5 parts of triethylamine (0.8 equivalent / carboxyl group) was added. Next, 645 parts of water was added to the acetone solution to carry out an emulsification / chain extension reaction, and then acetone was distilled off under reduced pressure at 40 to 80 ° C., and 3.7 parts of saturated aqueous ammonia (0.4 equivalent / carboxyl And the concentration was adjusted with water to obtain 1000 parts (A2) of an aqueous urethane resin dispersion having a solid content of 35% and a viscosity of 600 cP / 25 ° C.

Comparative Example 1 A urethane resin dispersion (A3) was prepared in the same manner as in Example 1 except that the NCO-terminated prepolymer of Example 1 was neutralized with 17.3 parts of triethylamine (0.8 equivalent / carboxyl group). ) Got.

Comparative Example 2 A urethane resin dispersion (A4) was obtained in the same manner as in Example 2 except that saturated aqueous ammonia was not added.

Test Example 1 The aqueous urethane resin dispersions (A1) and (A3) obtained in Example 1 and Comparative Example 1 were stored at 30 ° C., immediately after production, one month, two months and three months. The specific viscosity of each dried resin was measured by the following measurement method. Table 1 shows the results. A decrease in the specific viscosity indicates that the molecular weight of the resin has decreased due to hydrolysis. [Method of measuring specific viscosity] 0.714 g of dry resin was dissolved in 25 ml of dimethylformamide (DMF) to prepare a sample, the falling seconds were measured using a Cannon-Fenske viscometer, and the specific viscosity (ηsp) was calculated by the following equation. did. Specific viscosity (ηs
p) = (Sample falling seconds−DMF falling seconds) / DMF
Seconds of falling

[0022]

[Table 1]

Test Example 2 The urethane resin dispersions (A2) and (A4) obtained in Example 2 and Comparative Example 2 were stored at 30 ° C.
One month, two months and three months later, the melting start temperature of each dried resin was measured using a trace melting point measuring device [manufactured by Shimadzu Corporation]. Table 2 shows the results. The decrease in the melting start temperature indicates that the low molecular weight substances in the resin have increased due to hydrolysis.

[0024]

[Table 2]

[0025]

The aqueous dispersion of the carboxylate-type polyester-based polyurethane resin obtained by the production method of the present invention has good hydrolysis resistance and excellent long-term storage stability. Due to the above effects, the carboxylate-type polyester-based polyurethane resin aqueous dispersion obtained by the production method of the present invention is useful for various industrial uses such as aqueous paints, printing inks, adhesives, and fiber treatment agents.

Continued on the front page F term (reference) 4J002 CK031 DE027 EN026 EN036 EN046 GH00 GJ01 GK02 HA04 HA06 4J034 BA08 CA02 CA04 CA05 CA13 CA15 CA22 CB01 CB03 CB04 CB05 CB07 CB08 CC03 CC05 CC12 CC24 CC26 CC28 CC33 CC54 CC61 CC52 CC52 CC52 CC62 DA05 DB03 DB07 DF01 DF02 DF12 DF16 DF20 DF21 HA01 HA02 HA07 HB12 HC03 HC12 HC13 HC17 HC22 HC46 HC52 HC54 HC61 HC64 HC67 HC71 HC73 JA01 JA02 JA42 LB10 QC05 RA07 RA08 RA19 4J038 DG071 DG081 DG111 DG261 GA06

Claims (5)

[Claims] 1. Organic polyisocyanate (a), polyester polyol (b), hydroxycarboxylic acid (c)
And a method for producing an aqueous dispersion of a carboxylate type polyester-based polyurethane resin using a neutralizing agent (d) comprising a tertiary monoamine as an essential component, wherein 1.01 to 1.01 equivalent of a carboxyl group in the polyurethane. A method for producing an aqueous dispersion of a polyester-based polyurethane resin, comprising using 2 equivalents of (d). 2. A carboxyl group (-C) in a polyurethane.
OOH) based on the weight of the polyurethane resin.
The method according to claim 1, wherein the amount is 3 to 6% by weight. 3. The method according to claim 1, wherein the whole amount of (d) is added to the polyurethane and then dissolved or dispersed in water. 4. The method of claim 1, wherein the carboxyl groups in the polyurethane are present at a concentration of 0.1.
After neutralizing 6 to 0.95 equivalents with a tertiary monoamine and dissolving or dispersing in water to extend the chain, a tertiary monoamine and / or a primary or secondary monoamine is further converted to the (d) The total amount is 1.0 per equivalent of carboxyl group.
3. The method according to claim 1, wherein the amount is 1 to 2 equivalents. 5. An aqueous dispersion of a polyurethane resin produced by the method according to claim 1.