JPH0827243A - Aqueous polyurethane resin and its production - Google Patents

Abstract

PURPOSE:To obtain the subject resin containing a neutralized carboxyl group in the molecular chain, excellent in handleability, environmental pollution, uniformity, stability and drying property in coating and useful for coating, printing ink, adhesive, etc., by reacting a specific polyol with a polyisocyanate. CONSTITUTION:The objective resin is obtained by reacting (A) a carboxyl- containing polyester polyol having 250-5000 number-average molecular weight and obtained by carrying out ring opening polymerization of epsilon-caprolactam using dimethylolalkanoic acid as an initiator with (B) a polyisocyanate such as 4,4'-diphenylmethane diisocyanate and contains a carboxyl group neutralized with a basic substance such as triethylamine or triethanolamine in the molecular chain. The resin is obtained by reacting, e.g. the component A with the component B to afford a urethane prepolymer having terminal NCO, neutralizing the carboxyl group with the basic substance, dispersing or dissolving the prepolymer into water and extending the chain of the prepolymer with a chain extender.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an aqueous polyurethane resin and a method for producing the same. More specifically, the present invention relates to an aqueous polyurethane resin useful for applications such as paints, binders and adhesives, and a method for producing the same.

[0002]

2. Description of the Related Art Water-based polyurethane resins have hitherto been excellent in flexibility, mechanical properties, adhesiveness, etc.
It is used for binders and adhesives, etc. Recently, its development and utilization have been promoted more and more due to the movement of environmental improvement to limit atmospheric release of organic solvents.

To date, many attempts have been made to introduce a hydrophilic group into a polyurethane resin to make it aqueous, and among them, an anionic type resin having a carboxylate group introduced into the polyurethane chain has good water resistance, and is therefore actively studied. Has been done. The production method thereof includes polyisocyanate compounds, polyols, and carboxyls such as dimethylolpropionic acid as described in JP-B-61-5485, JP-B-3-48955, and JP-B-4-488. A method is mainly used in which a group-containing diol is reacted to form a urethane prepolymer having an NCO group terminal, a carboxyl group is neutralized with a basic substance, dispersed in water, and then chain extended with a polyamine compound.

However, when a urethane prepolymer is obtained by such a method, dimethylolpropionic acid is a polyisocyanate compound or a polyol, and acetone,
There is a problem that the solubility in an ordinary low boiling point organic solvent such as methyl ethyl ketone is poor, and when the reaction is carried out in a solvent-free or low boiling point organic solvent, the reaction system becomes non-uniform and a gelled substance is easily produced. Further, in order to carry out the prepolymerization reaction in a homogeneous system, it is necessary to use a high boiling point solvent such as dimethylformamide or N-methylpyrrolidone as a solvent capable of sufficiently dissolving dimethylolpropionic acid. Since it is difficult to remove the boiling point solvent, the high boiling point solvent will eventually remain in the aqueous resin solution, and there is a problem that the drying property and the working environment are lowered when the resulting aqueous polyurethane resin is applied.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a uniform and stable aqueous polyurethane resin without deteriorating the drying property and working environment at the time of application, and to facilitate the aqueous polyurethane resin. It is to provide a method that can be manufactured.

[0006]

The present invention has been made to solve the above-mentioned problems, and its gist is an aqueous polyurethane containing a carboxyl group neutralized with a basic substance in its molecular chain. In the resin, an aqueous polyurethane obtained by reacting a carboxyl group-containing polyester polyol having a number average molecular weight of 250 to 5000 obtained by ring-opening polymerization of ε-caprolactone to dimethylolalkanoic acid with a polyisocyanate compound. Exists in resin.

The present invention will be described in detail below. The carboxyl group-containing polyester polyol in the present invention is ε-containing dimethylolalkanoic acid as an initiator.
Number average molecular weight 2 obtained by ring-opening polymerization of caprolactone
It is a polyester polyol of 50 to 5000. Examples of dimethylolalkanoic acid include dimethylolpropionic acid, dimethylolbutanoic acid, and dimethylolheptanoic acid. Among them, dimethylolpropionic acid and dimethylolbutanoic acid are preferable from the viewpoint of industrial cost, and particularly Preferred is dimethylolpropionic acid.

Ring-opening polymerization of ε-caprolactone to dimethylolalkanoic acid, which is a carboxyl group-containing diol, is usually carried out by heating a mixture of the two without a catalyst while flowing an inert gas such as nitrogen gas. The reaction temperature is usually 100 to 200 ° C, preferably 130 to 180 ° C.
Is. At 100 ° C or lower, the mixture is not uniform and the reaction rate is extremely slow, and at 200 ° C or higher, gelation due to intermolecular dehydration reaction occurs, which is not preferable.

The number average molecular weight of the carboxyl group-containing polyester polyol is usually 250 to 5000, preferably 250 to 2500, and more preferably 300 to 10.
00. If the number average molecular weight is less than 250, the compatibility with other raw materials is poor during the prepolymer reaction, and the reaction tends to be nonuniform. If the number average molecular weight exceeds 5000, the crystallinity of the polyol is large and the solubility is high. And the content of the carboxyl group in the polyol is low, which is not preferable as a raw material for water-solubilization. From the viewpoint of increasing the degree of freedom in the composition of the polyol component, it is advantageous that the polyester polyol has a small number average molecular weight.
The content of the carboxyl group in the aqueous polyurethane resin can be adjusted according to the intended use,
Usually from 0.4 to 5% by weight of waterborne polyurethane resin solids
Is. If the content of the carboxyl group is less than 0.4% by weight, it is difficult to make the resin aqueous, and if the content of the carboxyl group exceeds 5% by weight, the physical properties of the coating film of the resin deteriorate.

In the present invention, a carboxyl group-containing polyester polyol having a number average molecular weight of 250 to 5,000 obtained by ring-opening polymerization of ε-caprolactone using dimethylolalkanoic acid as an initiator is used together with a carboxyl group-containing polyester polyol other than the carboxyl group-containing polyester polyol. A polyol can be used as the polyol component. The content of the carboxyl group in the solid content of the aqueous polyurethane resin can be adjusted, for example, by changing the proportion of the carboxyl group-containing polyester polyol in the polyol component, but the polyol component is all the carboxyl group-containing polyester polyol. May be.

As the polyol other than the above-mentioned carboxyl group-containing polyester polyol which is used as necessary in the present invention, for example, the average molecular weight is 400 to 500.
Polyethermethylene ether glycol, polypropylene glycol, polyethylene glycol and other polyether polyols having a degree of 0, polyethylene adipate having a bifunctional terminal hydroxyl group obtained by a condensation reaction of a diol and a dicarboxylic acid, polyethylene butylene adipate, polybutylene adipate, polypropylene Adipate, polyhexamethylene adipate, polyneopentylene adipate, poly-3-methyl-1,5-pentylene adipate, terephthalic acid alone or 1,6-hexanediol in combination with isophthalic acid and adipic acid, 3-methyl-
Condensation reaction products with 1,5-pentanediol and the like, polyester polyols such as polycaprolactone and polymethylvalerolactone, polycarbonate polyols,
Examples include silicone polyols, polybutadiene polyols, polyolefin polyols and the like. These polyols may be used alone or in combination of two or more.

Further, if necessary, ethylene glycol,
Propylene glycol, diethylene glycol, 1,4
-Butanediol, neopentyl glycol, 1,6-
Short chain diols such as hexanediol and 3-methyl-1,5-pentanediol may be used together with the polyol component. Examples of the polyisocyanate compound in the present invention include aromatic diisocyanates such as 4,4′-diphenylmethane diisocyanate, 2,4- or 2,6-tolylene diisocyanate, 1,5-naphthalene diisocyanate, p- or m-phenylene diisocyanate. Alicyclic diisocyanates such as isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, 1,4-cyclohexylene diisocyanate and hydrogenated products of tolylene diisocyanate, aliphatic diisocyanates such as hexamethylene diisocyanate, xylylene diisocyanate, m- Examples thereof include tetramethylxylylene diisocyanate. Of these, alicyclic diisocyanates are preferable because they are easy to produce, the stability of the resin in water is good, and they do not yellow. These polyisocyanate compounds may be used alone or in combination of two or more.

In the present invention, when a carboxyl group is introduced into a polyurethane chain or a urethane prepolymer chain, a polyester polyol having a number range of a number average molecular weight in a specific range obtained by ring-opening polymerization of ε-caprolactone with dimethylolalkanoic acid and poly It is based on the finding that a uniform and stable aqueous polyurethane resin can be obtained by reacting with an isocyanate compound,
The carboxyl group in the polyurethane chain or urethane prepolymer chain is neutralized by using a basic substance.

In the present invention, the basic substance used to neutralize the carboxyl group in the polyurethane chain or urethane prepolymer chain is a tertiary amine such as trimethylamine, triethylamine, methyldiethylamine, tripropylamine, dimethylethanolamine, Examples thereof include alkanolamines such as methyldiethanolamine and triethanolamine, and hydroxides and carbonates of ammonia, alkali metals such as sodium and potassium.
Preferred as these basic substances are tertiary amines and alkanolamines. These are usually added in a ratio of 0.5 to 1 equivalent to 1 equivalent of the carboxyl group of the urethane prepolymer.

The aqueous polyurethane resin of the present invention can be produced by a known method, and the production method is not particularly limited, but a preferred production method is ε-caprolactone ring-opening polymerization using dimethylolalkanoic acid as an initiator. The urethane component having a terminal NCO group is reacted with a polyol component containing a carboxyl group-containing polyester polyol having a number average molecular weight of 250 to 5,000 and a polyisocyanate compound, and the carboxyl group is neutralized with a basic compound. It is a method for producing an aqueous polyurethane resin, which is dispersed or dissolved in water and extended with a chain extender.

As the chain extender optionally used for chain extending the urethane prepolymer having a terminal NCO group in the present invention, a polyamine compound is preferable and ethylenediamine, 1,2-propanediamine, tetramethylenediamine, hexa Methylenediamine, 1,4-
Cyclohexylene diamine, isophorone diamine, 4,
Diamines such as 4'-dicyclohexylmethanediamine, m-xylylenediamine and phenylenediamine, polyethylene polyamines such as diethylenetriamine, triethylenetetramine and tetraethylenepentamine, hydrazine, piperazine and dihydrazide of hydrazine with adipic acid and phthalic acid. Examples include compounds. Moreover, you may use the said short chain diol. These may be used alone or in combination of two or more. Also,
When it is desired to introduce a hydroxyl group at the terminal of polyurethane, monoethanolamine or diethanolamine can be used, and when an hydroxyl group is to be introduced into the main chain, aminoethylaminoethanol or the like can be used in combination with the polyamine compound.

The urethane prepolymer having a terminal NCO group may be used as it is without reacting with a solvent. However, in order to facilitate the operation of adding water later and emulsifying and dispersing in an oil-in-water type,
More preferably, the viscosity of the urethane prepolymer is lowered by diluting with a small amount of a low boiling point organic solvent or by reacting in a solution of a small amount of a low boiling point organic solvent in advance. At this time, the equivalent ratio of the polyisocyanate compound and the polyol component is usually NC.
It is preferable to react with O / OH = 1.1 / 1 to 6/1.

The low boiling point organic solvent used for the reaction of the urethane prepolymer is usually removed after the resin is made water-based.
In order to facilitate the removal, those having a boiling point of 100 ° C. or lower are preferable, and examples thereof include acetone, methyl ethyl ketone, tetrahydrofuran and the like. Among the solvents used, acetone and methyl ethyl ketone are preferable, and acetone is the most preferable.

The urethanization reaction is usually carried out in a nitrogen stream without a catalyst. When a catalyst is used, for example, an organometallic catalyst such as dibutyltin dilaurate, dibutyltin dioctoate, dibutyltin diacetate, a triethylenediamine or the like is used. A tertiary amine catalyst or the like can be used. The reaction temperature is usually selected in the range of 20 to 120 ° C. On the other hand, the reaction time is
It depends on the reaction temperature and the like and cannot be determined unconditionally, but it is usually about 1 to 20 hours.

When an organic solvent is used in the reaction of the aqueous polyurethane resin, in order to remove the solvent, air or nitrogen gas or the like is sent to the surface or the liquid of the reaction product at a temperature not higher than the boiling point of water, usually 30 to 100 ° C. Any method such as a method of removing the solvent, a method of removing the solvent by reducing the pressure in the reaction vessel, or a method of using a thin film distiller can be used. Further, one of the objects of the present invention is to obtain an aqueous polyurethane in which an organic solvent hardly remains. However, in an application in which the use of a small amount of an organic solvent is allowed, the organic solvent is used during the production of the aqueous polyurethane resin and the reaction is performed as it is. It can also be left in the product.

The solid content of the aqueous polyurethane resin finally obtained in the present invention is usually 10 to 70% by weight, and the average particle diameter of polyurethane particles dispersed in water is 5 μm or less. The appearance of the resin changes depending on the size of the dispersed particles, and when the average particle size is small, it exhibits a solution state that fluoresces, and when the average particle size is large, it becomes a white emulsion, but both are stable over time. Retains properties. The solid content and viscosity can be adjusted by controlling the size of the polyurethane dispersed particles according to the application. When the amount of hydrophilic groups in the polyurethane resin is decreased, the dispersed particles tend to be large, and when the amount of hydrophilic groups is increased, the particles tend to be small. The number average molecular weight of the aqueous polyurethane resin of the present invention is usually 6,000 to 50.
10,000, preferably 7,000 to 300,0
00, more preferably 8,000 to 150,000.

Here, the number average molecular weight is a value measured by GPC with 1% by weight of tetrahydrofuran and converted into polystyrene. The aqueous polyurethane resin of the present invention is suitable for various paints, binders, adhesives and the like and can be used as it is as a single liquid. However, if necessary, an aqueous block type isocyanate curing agent or an aqueous dispersion type isocyanate curing that does not block NCO groups is used. It is also possible to use a mixture of two liquids with a curing agent, a melamine-based curing agent, a polyaziridine compound or the like as a crosslinking agent. At this time, various additives such as an antioxidant, an ultraviolet stabilizer, a colorant, a defoaming agent, a flow control agent, a water repellent, and a filler can be blended with the aqueous polyurethane resin, if necessary.

[0023]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples unless it exceeds the gist thereof. In the examples, part,%
Indicates the parts by weight and% by weight, respectively. The methods for measuring each physical property in the examples are as follows.

Mechanical Properties: Film is punched out with a blade 10
Cut into 120 mm, and according to JIS K6301, Toyo Baldwin Co., Ltd. Tensilon UTM-III-10
At 0, the tensile strength and elongation were measured at a tensile speed of 500 mm / min. Viscosity: The viscosity at 25 ° C was measured using an EM type rotational viscometer manufactured by Tokyo Keiki Co., Ltd. Average particle diameter: measured using a viscosity distribution measuring device manufactured by Horiba Ltd.

[Production Example 1] A reactor was charged with 335 parts of dimethylolpropionic acid and 570 parts of ε-caprolactone, heated under stirring under a N ₂ stream while being uniformly dissolved, and then reacted at 150 ° C. for 4 hours. A carboxyl group-containing polyester polyol having a number average molecular weight of 362 was obtained. This is Polyol A.

[Production Example 2] 134 parts of dimethylolpropionic acid and 684 parts of ε-caprolactone were charged in a reactor and reacted in the same manner as in Production Example 1 to obtain a carboxyl group-containing polyester polyol having a number average molecular weight of 818. This is Polyol B.

Example 1 93.6 parts of 4,4'-dicyclohexylmethane diisocyanate and 228.6 parts of polybutylene adipate having a number average molecular weight of 2000 were placed in a reactor.
Polyol A3 having a number average molecular weight of 362 obtained in Production Example 1
6.2 parts and 89.6 parts of acetone were charged and reacted at 60 ° C. for 7 hours while stirring under a nitrogen stream to obtain a uniform solution of urethane prepolymer having NCO group. Then, 9.1 parts of triethylamine and 67.9 parts of acetone were added for neutralization.

400 parts of demineralized water was gradually added thereto to prepare an oil-in-water type urethane prepolymer dispersion, and 6.4 parts of hydrazine hydrate and 57.0 parts of demineralized water were added at 50 ° C., and then the reaction solution was added. Nitrogen gas was blown into the mixture to remove the solvent at 60 ° C. for 3 hours to obtain a solid content of 45% and a viscosity of 200 mPa.s. s /
An aqueous polyurethane resin having an average particle size of 0.5 μm at 25 ° C. was obtained.

When this was applied onto a glass plate with a gap of 250 μm and dried at 80 ° C. for 2 hours, a uniform transparent and flexible film having a thickness of about 70 μm was obtained. 23 ° C, 60% RH
After leaving for 1 day, the result of the tensile test in the same environment,
It showed good physical properties such as a tensile strength of 33 MPa and an elongation of 620%. Dissolve the film in tetrahydrofuran at 1%, G
As a result of measuring the molecular weight by PC (gel permeation chromatograph), the number average molecular weight is 1 in terms of polystyrene.
It was 8000.

Example 2 83.3 parts of isophorone diisocyanate, 125 parts of polytetramethylene ether glycol having a number average molecular weight of 1000 and polyol B 102. of the number average molecular weight of 818 obtained in Production Example 2 were placed in a reactor.
3 parts were charged and reacted at 80 ° C. for 5 hours with stirring under a nitrogen stream to obtain a uniform transparent NCO group-terminated urethane prepolymer. Then the temperature is raised to 50 ° C. and triethylamine 1
The mixture was neutralized by adding 1.4 parts and 107.3 parts of acetone.

To this, 410 parts of demineralized water was gradually added to obtain an oil-in-water urethane prepolymer dispersion, and 19.1 parts of isophoronediamine and 101.6 parts of demineralized water were added at 30 ° C. to prepare a chain of prepolymer. I made an extension. Thereafter, nitrogen gas was blown into the reaction solution to remove the solvent for 3 hours at 60 ° C., solid content 40%, viscosity 420 mPa.s. An aqueous polyurethane resin having an average particle size of 0.3 μm was obtained at s / 25 ° C. A uniform transparent film was obtained in the same manner as in Example 1, and the tensile strength was 4
It showed good physical properties of 2 MPa and an elongation of 540%. Also,
The number average molecular weight of the obtained polyurethane resin is 32,000.
Met.

EXAMPLE 3 78.6 parts of 4,4'-dicyclohexylmethane diisocyanate and 100 parts of polycarbonate polyol having a number average molecular weight of 2000 were placed in a reactor.
100 parts of polytetramethylene ether glycol having a number average molecular weight of 2000, the number average molecular weight of 3 obtained in Production Example 1
36.2 parts of Polyol A of 62 and 78.7 of acetone
A portion was charged and reacted at 60 ° C. for 7 hours while stirring under a nitrogen stream to obtain a uniform solution of NCO-terminated urethane prepolymer. Next, 9.1 parts of triethyleneamine and 60.
1 part was added to neutralize.

400 parts of demineralized water was gradually added thereto to obtain an oil-in-water type urethane prepolymer dispersion, and at 30 ° C., 7.7 parts of isophoronediamine, 2.3 parts of hydrazine hydrate and 100.7 parts of demineralized water. Was added to extend the chain of the urethane prepolymer. Then, nitrogen gas was blown into the reaction solution to remove the solvent at 60 ° C. for 3 hours to obtain a solid content of 40% and a viscosity of 24%.
0 mPa. An aqueous polyurethane resin having an average particle size of 0.4 μm was obtained at s / 25 ° C. A uniform transparent film was obtained in the same manner as in Example 1, with a tensile strength of 40 MPa and an elongation of 58.
The physical properties were as good as 0%. The number average molecular weight of the obtained polyurethane resin was 25,000.

Example 4 98.3 parts of 4,4'-dicyclohexylmethane diisocyanate, polyester polyol 187.5 having a number average molecular weight of 2000 of terephthalic acid and 3-methyl-1,5-pentanediol were placed in a reactor.
Part, Polyol B having a number average molecular weight of 818 obtained in Production Example 2
51.1 parts and 84.2 parts of acetone were charged and reacted at 60 ° C. for 7 hours while stirring under a nitrogen stream to obtain a uniform solution of the NCO group-terminated prepolymer. To this was added 5.7 parts of triethylamine and 62.6 parts of acetone for neutralization.

To this, 280 parts of demineralized water was gradually added to obtain an oil-in-water type urethane prepolymer dispersion, and 5.6 parts of hydrazine hydrate and 68.2 parts of demineralized water were added at 50 ° C. to add urethane prepolymer chains. I made an extension. Then, nitrogen gas was blown into the reaction solution to remove the solvent for 3 hours at 60 ° C.
0%, viscosity 80 mPa.s. s / 25 ° C, average particle size 0.7
A μm aqueous polyurethane resin was obtained. A uniform transparent film was obtained in the same manner as in Example 1, and the tensile strength was 48 MP.
and a good elongation of 530%. The number average molecular weight of the obtained polyurethane resin was 30,000.

[Comparative Example 1] 9,43.6 parts of 4,4'-dicyclohexylmethane diisocyanate and 228.6 parts of polybutylene adipate having a number average molecular weight of 2000 were placed in a reactor.
Dimethylolpropionic acid 13.4 parts and acetone 8
3.9 parts were charged and the mixture was stirred at 60 ° C. for 7 hours under a nitrogen stream. Most of dimethylolpropionic acid in the reaction solution was insoluble, and a uniform urethane prepolymer could not be obtained.

[Comparative Example 2] The reaction was carried out by increasing the liquid temperature to 90 ° C with the solventless formulation of Comparative Example 1 except for acetone. Dimethylolpropionic acid was insoluble and dispersed in the reaction liquid, and after a while, heat was generated and the liquid temperature rose to 115 ° C. When the reaction was continued as it was, the reaction solution became a gel and a uniform urethane prepolymer was not obtained.

[0038]

The water-based polyurethane resin obtained by the present invention is excellent in working environment during handling and application, and is excellent in drying property when applied, and is uniform and stable. It is useful in a wide range of applications such as binders and adhesives. Further, according to the production method of the present invention, it is possible to easily produce a uniform and stable aqueous polyurethane resin which is excellent in work environment property and drying property.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location C09D 175/04 PHQ C09J 175/04 JFB

Claims (4)

[Claims] 1. An aqueous polyurethane resin containing a carboxyl group neutralized with a basic substance in its molecular chain,
An aqueous polyurethane resin obtained by reacting a carboxyl group-containing polyester polyol having a number average molecular weight of 250 to 5000 obtained by ring-opening polymerization of ε-caprolactone to dimethylolalkanoic acid with a polyisocyanate compound. 2. The aqueous polyurethane resin according to claim 1, wherein the content of the carboxyl group in the aqueous polyurethane resin is 0.4 to 5% by weight of the solid content of the aqueous polyurethane resin. 3. The number average molecular weight of the polyurethane resin in the aqueous polyurethane resin is 6000 to 500000.
The aqueous polyurethane resin according to claim 1 or 2, wherein 4. A number average molecular weight of 250-5 obtained by ring-opening polymerization of ε-caprolactone to dimethylolalkanoic acid.
After reacting a polyol component containing 000 carboxyl group-containing polyester polyols with a polyisocyanate compound to form a urethane prepolymer having a terminal NCO group, the carboxyl group is neutralized with a basic compound and dispersed or dissolved in water to form a chain. A method for producing an aqueous polyurethane resin, which comprises chain extension with an extender.