JPH07188373A - Thermally cross-linkable polyurethane emulsion composition - Google Patents

Abstract

PURPOSE:To obtain a thermally cross-linkable polyurethane emulsion composition capable of being made into a one pack type, containing a positively introduced functional group to be reacted with a blocked lsocyanate-based cross- linking agent. CONSTITUTION:A compound containing two or more active hydrogen atoms is reacted with an organic polyisocyanate to give a urethane prepolymer containing an isocyanate group at the molecular end, which is dispersed into water, emulsified and then reacted with a polyamine containing at least two or more active amino groups so as to make the molar ratio of (end NCO group of the urethane prepolymer)/(polyamine) of >=1/1. The active amino group- containing polyurethane emulsion obtained by the reaction is mixed with a blocked isocyanate group-containing compound to give the objective thermally cross-linkable polyurethane emulsion composition.

Description

Detailed Description of the Invention

[0001]

The present invention is excellent in one-liquid workability,
The present invention also relates to a polyurethane emulsion composition having particularly excellent heat-crosslinking properties.

[0002]

2. Description of the Related Art Polyurethane resins have hitherto been useful materials as adhesives, paints and modifiers, and have been used in a wide variety of applications. On the other hand, from the viewpoint that the environment is polluted by the atmospheric dispersion of the solvent used in the solvent-based synthetic resin and is harmful to the human body, the water-soluble or aqueous emulsion-based synthetic resin has recently been rapidly regarded as beneficial. . Also in the polyurethane resin, a water-soluble or aqueous emulsion type is being used in the field of adhesives, paints, etc., instead of the conventional solvent type dissolved in an organic solvent, and its use is expanding toward the future.

Two types of water-soluble or water-based emulsion type polyurethane resins are known, one of which is a relatively low-molecular type polyurethane resin which utilizes a blocked isocyanate group.
It is a heat-reactive polyurethane emulsion in the medium molecular weight range, and the other is a polyurethane emulsion in the relatively high molecular weight range mainly composed of a linear structure.

In these polyurethane emulsions, a hydrophilic group such as anionic, cationic or nonionic is introduced into the urethane resin skeleton to impart self-emulsifying dispersibility and then dispersed in water, or , A hydrophobic urethane resin added with an emulsifier and forcibly dispersed in water.

[0005]

However, the above polyurethane emulsion has the following problems. That is,
In the heat-reactive polyurethane emulsion using the blocked isocyanate group, a network structure is formed by a heat reaction, which is excellent in solvent resistance of a film, adhesion to an adherend, heat-resistant adhesion, etc. Moreover, since a heating operation of high temperature treatment is required, the use is restricted by the processing conditions resulting from the heat resistance of the equipment surface and the adherend. It is also not preferable from the viewpoint of energy saving in recent years.

On the other hand, in the polyurethane emulsion mainly composed of the linear structure, since the polyurethane film layer is formed only after being dried, the application is not limited as in the heat-reactive polyurethane emulsion, and it can be widely used. it can. However, this polyurethane emulsion is basically composed of a linear-structured polyurethane as a main component and is thermoplastic, so that, for example, performance such as heat-resistant adhesiveness, solvent resistance, warm water resistance, chemical resistance, etc. is poor. Performance improvement is desired.

Therefore, in order to improve various problems of the above polyurethane emulsion, conventionally, melamine type such as trimethylolmelamine, aziridine type, epoxy type,
Attempts have been made to blend various crosslinking agents typified by blocked isocyanates. As a result, although some performance improvements have been recognized, most of them are still insufficient in performance. In addition, the fact that the temperature is higher than the cleavage temperature of the reactive group of the cross-linking agent has not been satisfied yet. The main cause of insufficient performance improvement is due to only the IPN (interpenetrating network) entanglement due to self-polymerization of the polyurethane resin and the cross-linking agent, because the polyurethane contained does not have a functional group that reacts with the cross-linking agent. This is because it only improves the physical properties. In addition, blending the above-mentioned melamine-based, aziridine-based, epoxy-based and other crosslinking agents into a one-pack solution deteriorates the storage stability of the emulsion and cannot be practically used.

[0008] Therefore, there is a great demand for a polyurethane emulsion which can be made into one liquefaction and which is positively introduced with a functional group capable of reacting with a blocked isocyanate cross-linking agent. Another object is to provide a polyurethane emulsion composition.

[0009]

To achieve the above object, the heat-crosslinkable polyurethane emulsion composition of the present invention is obtained by reacting a compound having two or more active hydrogen atoms with an organic polyisocyanate. In a water dispersion of a urethane prepolymer having an isocyanate group at the molecular end, a polyamine having at least two or more active amino groups is added, and the molar ratio of (terminal NCO group of urethane prepolymer) / (polyamine) is It is characterized by containing an active amino group-containing polyurethane emulsion obtained by adding so as to be 1/1 or more, and a blocked isocyanate group-containing compound.

The amine value (Am · V) per solid component of the active amino group-containing polyurethane emulsion is preferably 5 (KOHmg / g) or more, 7
It is more preferable that it is (KOHmg / g) or more.

Furthermore, a blocked isocyanate group-containing compound is added to the active amino group-containing polyurethane emulsion at a molar ratio of (active amino group in the active amino group-containing polyurethane) / (regenerated isocyanate group) of 1 /
It is preferable to mix it in the range of 0.5 to 1/2, and it is more preferable to mix it in the range of 1 / 0.8 to 1 / 1.5.

The heat-crosslinkable polyurethane emulsion composition of the present invention is prepared by blending a blocked isocyanate group with the active amino group-containing polyurethane emulsion as described above. The active amino group-containing polyurethane emulsion is introduced into the polyurethane skeleton. Since it contains an active amino group, when a blocked isocyanate group-containing compound is used in combination, a cross-linking reaction is rapidly caused by heat treatment. As a result, the physical properties of the coating film produced using the heat-crosslinkable polyurethane emulsion composition of the present invention are remarkably improved. In addition, since it is a one-component emulsion having a latent crosslinking agent, there are few restrictions in terms of processing conditions.

The heat-crosslinkable polyurethane emulsion composition of the present invention will be described in more detail below. First,
The urethane prepolymer having an isocyanate group at the molecular end used for producing the emulsion composition of the present invention is 2
It can be obtained by reacting a compound having one or more active hydrogen atoms with an excess amount of an organic polyisocyanate in the presence or absence of a solvent.

The above-mentioned compound having two or more active hydrogen atoms has two or more hydroxy groups, carboxyl groups, amino groups, mercapto groups or the like at the molecular end or in the molecule, and is a generally known polyether, Polyester, polyether ester, polythioether, polyacetal, polybutadiene, polysiloxane, etc.,
Preferred are polyethers or polyesters having two or more hydroxy groups at the molecular ends. The molecular weight of the compound having two or more active hydrogen atoms is 50
It is preferably in the range of to 5,000.

If necessary, a chain extender may be added to the compound having two or more active hydrogen atoms. Specific examples of the chain extender include low molecular weight 1,4-butanediol. , 1,6-hexanediol, 3-methyl-
1,5-pentanediol, ethylene glycol, neopentyl glycol, diethylene glycol, trimethylolpropane, cyclohexanedimethanol, etc. may be mentioned.

On the other hand, as the above-mentioned organic polyisocyanate, aromatic, aliphatic or alicyclic organic polyisocyanates which have been conventionally used can be used.
Tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate,
Examples include organic polyisocyanates such as tetramethylxylylene diisocyanate, and mixtures thereof.

As will be described later, in consideration of the reaction of the obtained urethane prepolymer with the polyamine after the emulsification and dispersion, and the subsequent maintenance and storage stability of the emulsified dispersion system, the organic polyisocyanate used is Is particularly preferably an alicyclic polyisocyanate represented by dicyclohexylmethane diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, or an organic polyisocyanate having a tertiary isocyanate group represented by tetramethylxylylene diisocyanate. In addition, a mixture of these organic polyisocyanates and aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, xylylene diisocyanate and the like, and aliphatic polyisocyanates such as the hexamethylene diisocyanate are also particularly preferable. It is preferable to mix at least an equimolar amount or more of the alicyclic polyisocyanate or the organic polyisocyanate having the tertiary isocyanate group with the isocyanate group at the terminal of the urethane prepolymer molecule.

The reaction of the above-mentioned compound having two or more active hydrogen atoms with an excess amount of an organic polyisocyanate is carried out by a conventionally known one-step or multi-step isocyanate addition reaction method under a temperature condition of 50 to 120 ° C. Done in.

In the above method, if necessary, a reaction control agent such as phosphoric acid, adipic acid, benzoyl chloride, a reaction catalyst such as dibutyltin dilaurate, stannas octoate, triethylamine, and an organic solvent that does not react with an isocyanate group are used. It may be added during or after the reaction.

Examples of the organic solvent include acetone, methyl ethyl ketone, tetrahydrofuran, dioxane, ethyl acetate, toluene, xylene and the like. Considering that the polyurethane emulsion composition obtained by the present invention is an aqueous emulsion and the solvent recovery described later, acetone, methyl ethyl ketone, and ethyl acetate are more preferable.

Further, in the above-mentioned addition reaction method, if necessary, a stabilizer such as an antioxidant or an ultraviolet absorber may be added during the reaction or after the completion of the reaction.

The urethane prepolymer thus obtained has a terminal isocyanate group content of 5 to 0.5% by weight.
Is preferred and 3 to 1% by weight is particularly preferred. If the content of the terminal isocyanate group is 5% by weight or more, the polyurethane emulsion composition obtained by emulsion destruction and gelation at the reaction step with the polyamine described below or the product stability and temporal stability of the obtained polyurethane emulsion composition are poor. Becomes Further, when the content of the terminal isocyanate group is 0.5% by weight or less, the introduction amount of the active amino group due to the reaction with the polyamine described later is reduced, and the crosslinking modifying effect of the blocked isocyanate-based crosslinking agent is exhibited. There is a problem such as not being done.

Next, the urethane prepolymer obtained above is dispersed in water for emulsification. The following four methods can be adopted as the treatment method to be performed before the dispersion in water. That is, (1) in the step of preparing the urethane prepolymer, a carboxyl group-containing polyol component, for example, a carboxyl group obtained by the reaction of dimethylolpropionic acid or the like with an organic polyisocyanate is previously introduced into the molecule, and then the carboxyl group is introduced. A method in which the group is neutralized with a basic compound such as triethylamine, trimethylamine, diethanolmonomethylamine, dimethylethanolamine, caustic soda, and caustic potassium to convert it into a carboxyl group salt. (2) After preparation of the urethane prepolymer, HLB A method of adding and mixing a nonionic activator having a value of 6 to 18 at 50 ° C. or lower (however, the amount of the nonionic activator used is based on the urethane prepolymer in consideration of the emulsification dispersibility and the water resistance of the product film). 2 to 15% by weight), (3) the urethane After the polymer preparation, from 50 to 5% of the terminal isocyanate groups, preferably 30
A method of reacting an aqueous solution of sodium salt or potassium salt of aminoethanesulfonic acid, aminoacetic acid or the like corresponding to ˜5%, and (4) in the step of preparing the urethane prepolymer, a tertiary nitrogen-containing polyol component in the molecule in advance, for example, N
-Introducing a tertiary nitrogen atom by the reaction of methyl-diethanolamine or the like with an organic polyisocyanate, and then quaternizing the tertiary nitrogen atom with diethyl sulfate, dimethyl sulfate, benzyl chloride, methyl chloride or the like. Method.

Water is added to the urethane prepolymer which has been subjected to any one of the above treatments (1), (2), (3) and (4),
Emulsify using an emulsification / dispersion device such as a homomixer or homogenizer. When this operation is carried out, the emulsion dispersion temperature is preferably low in order to suppress the reaction between the terminal isocyanate group of the urethane prepolymer and water.

After emulsifying the urethane prepolymer in water, a polyamine compound having at least two or more active amino groups is then added, and the terminal isocyanate group of the urethane prepolymer and the amino group of the polyamine compound are added in an emulsion dispersion system. And the polyamine addition reaction is carried out.

Examples of the polyamine compound having at least two active amino groups include ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, xylylenediamine, isophoronediamine, diphenylmethanediamine, hydrogenated diphenylmethanediamine, hydrogenated xylylenediamine. Examples include amines. Of these, compounds having both a primary amino group and a secondary amino group in the molecule, such as diethylenetriamine and triethylenetetramine, are preferable because they can be stably produced with less generation of aggregates.

The amount of the above polyamine compound used is determined so that the molar ratio of (terminal NCO group of urethane prepolymer) / (polyamine) is 1/1 or more. Further, the Am · V (amine value) in the obtained active amino group-containing polyurethane emulsion is 5 (KOHmg
/ G) or more, the polyamine compound is preferably used, and more preferably 7 (KOHmg / g) or more. When this molar ratio is smaller than 1/1 (when the number of moles of polyamine is large), free polyamine exists and it is not preferable in terms of toxicity. on the other hand,
When Am · V (amine value) in the active amino group-containing polyurethane is less than 7 (KOHmg / g) per solid content, even when the resulting emulsion composition is used in combination with the blocked isocyanate group-containing compound, The effect of improving the physical properties of the coating film decreases due to the cross-linking reaction, and 5 (KOHm
If it is smaller than g / g), the combined effect becomes smaller.

In the polyamine chain extension reaction in the above emulsion dispersion system, an emulsion dispersion device such as a homomixer or a homogenizer is used to carry out a uniform reaction.
The reaction temperature is in the range of 5 to 40 ° C., preferably 5 to 25 ° C., in consideration of gelation caused by rapid reaction or emulsion reaction due to local reaction, and subsequent product stability and temporal stability. Then, the polyamine addition reaction is usually carried out for 10 to 60 minutes.

In order to effectively carry out the reaction between the isocyanate group of the urethane prepolymer and the amino group of the polyamine compound and to suppress the side reaction between water and the isocyanate group, phosphoric acid, hydrochloric acid, benzoyl chloride, etc. Can be added.

When the resulting active amino group-containing polyurethane emulsion contains an organic solvent, the active amino group-containing polyurethane emulsion containing no organic solvent can be obtained by distilling off under reduced pressure and heating conditions if necessary. .

The thermally crosslinkable polyurethane emulsion of the present invention can be obtained by blending the obtained active amino group-containing polyurethane emulsion with the blocked isocyanate group-containing compound. The compounding amount of the blocked isocyanate group-containing compound is such that the molar ratio of (active amino group in active amino group-containing polyurethane emulsion) / (regenerated isocyanate group) is within the range of 1 / 0.5 to 1/2. It is preferable to blend as follows, and 1 / 0.8 to 1 /
It is more preferable that the compounding amount be within the range of 1.5. When this molar ratio is larger than 1 / 0.8 (when the molar ratio of the regenerated isocyanate group is small), the effect of improving the physical properties of the coating film due to the crosslinking reaction becomes gradually smaller and 1
If it is larger than /0.5, the effect is further reduced, which is not preferable. Further, when this molar ratio is smaller than 1 / 1.5 (when the molar ratio of the regenerated isocyanate group is large), heat treatment conditions of high temperature and long time are required, and
If it is smaller, the tendency is further increased, which is not preferable.

Examples of the blocked isocyanate group-containing compound include compounds obtained by blocking an organic polyisocyanate with a blocking agent, and examples of the blocking agent include known compounds such as phenol-based compounds and alcohol-based compounds.
Examples thereof include active methylene type, lactam type, oxime type, mercaptan type and the like. Considering the storage stability of the emulsion composition of the present invention, phenol-based blocking agents such as phenol and cresol, lactam-based blocking agents such as ε-caprolactam, and oxime-based blocking agents such as methylethylketoxime and cyclohexanone oxime are preferable.
As the blocking agent for aromatic isocyanates,
A raftam system such as ε-caproraftam having a high thermal dissociation temperature is preferable from the viewpoint of storage stability.

As a method of blending the above-mentioned blocked isocyanate group-containing compound, the following methods may be mentioned. (1) A method of emulsifying the blocked isocyanate group-containing compound in water with an emulsifier and then mixing, (2) a method of mixing the blocked isocyanate group-containing compound with the urethane prepolymer and then emulsifying, and (3) Examples include a method of emulsifying the urethane prepolymer in which excess isocyanate groups are blocked with a blocking agent and then blending.

[0034]

In the heat-crosslinkable polyurethane emulsion composition of the present invention, since the urethane prepolymer is emulsified and dispersed in water in the step after the urethane prepolymer is prepared by using the organic polyisocyanate, the isocyanate of the prepolymer is used. The side reaction between the group and water is suppressed, and further, the reaction with the polyamine in the emulsified dispersion system and the subsequent maintenance of the emulsified dispersion system and improvement of storage stability are achieved.

The heat-crosslinkable polyurethane emulsion composition of the present invention can be obtained by adding a polyamine having at least two amino groups to the urethane prepolymer after emulsification and dispersion. As a result, a part of the amino groups of the polyamine undergoes an addition reaction with the isocyanate groups of the prepolymer to obtain an active amino group-containing polyurethane emulsion having excess amino groups introduced into the polyurethane skeleton. By blending this active amino group-containing polyurethane emulsion with a blocked isocyanate group-containing compound, a heat-crosslinkable polyurethane emulsion composition can be obtained. The heat-crosslinkable polyurethane emulsion composition thus obtained can be made into a high molecular weight substance as in the case of conventional polyurethane emulsions. It develops physical properties such as chemical properties.

Further, since the thermally crosslinkable polyurethane emulsion composition obtained by the present invention positively introduces an active amino group into the polyurethane skeleton, when a blocked isocyanate which functions as a crosslinking agent is used in combination,
By the heat treatment, the active amino group rapidly cross-links with the blocked isocyanate. By the crosslinking reaction between the active amino group and the blocked isocyanate group crosslinking agent, the physical properties of the coating film formed can be further improved as compared with the conventional polyurethane emulsion.

[0037]

The heat-crosslinkable polyurethane emulsion composition provided by the present invention is constituted as described above, and exhibits the remarkable effects as described below.

That is, in this heat-crosslinkable polyurethane emulsion composition, since the active amino group is positively introduced into the polyurethane skeleton, the heat treatment causes a rapid crosslinking reaction with the blocked isocyanate as the crosslinking agent. A remarkable effect that a coating film which is superior in physical properties such as strength, warm water resistance and solvent resistance to the coating film obtained from the conventional polyurethane emulsion can be obtained.

Further, since this heat-crosslinkable polyurethane emulsion composition is rapidly heat-crosslinked, the physical properties of the coating film obtained when the processing speed is fast and the processing is carried out in a short time are remarkably improved. Furthermore, since it can be processed at a relatively low temperature, it can be used for applications where high temperature processing is not possible. Therefore,
The heat-crosslinkable polyurethane emulsion composition of the present invention,
It can be applied to a wide range of processing conditions and applications.

The heat-crosslinkable polyurethane emulsion composition of the present invention includes, specifically, fibers, knits, woven fabrics, non-woven fabrics,
It can be used for impregnation of wood, paper, leather, metal, plastic, etc., coating, adhesive, paint, vehicle for ink, etc. In particular, impregnation of plastic, paper, metal, etc., which requires low-temperature processing and requires high processing speed,
It can be used for coatings, adhesives, paints, vehicles for inks, etc.

Further, the heat-crosslinkable polyurethane emulsion composition according to the present invention has the following ionic properties.
Good compatibility with other water-based resin emulsions such as vinyl acetate, ethylene vinyl acetate copolymer, acrylic ester resin emulsion and rubber latex such as natural rubber, SBR, NBR, etc. It is useful.

[0042]

EXAMPLES Examples of the present invention will be described below.
The present invention is not limited to these. Incidentally, "parts" in Examples, Comparative Examples, Experimental Examples and Comparative Examples described later.
And "%" indicate parts by weight and% by weight, respectively, unless otherwise specified.

(Preparation of Blocked Isocyanate Group-Containing Compound) <Blocked Isocyanate Group-Containing Compound A> Hexamethylene diisocyanate adduct of trimethylolpropane (trimethylolpropane: hexamethylenediisocyanate = 1: 3, diluted with ethyl acetate, solid content) 75%, free isocyanate group 12.8%) 500 parts was dissolved in ethyl acetate 300 parts, and then methyl ethyl ketoxime 14
0 part was gradually added dropwise with stirring to cause a reaction, and a blocked isocyanate group-containing compound A was obtained. The content of free isocyanate groups of this blocked isocyanate group-containing compound A was examined. Regarding the content of free isocyanate group, about 1 g of the isocyanate group-containing compound A was precisely weighed, and 0.1 N di-n-butylamine (toluene solution) 3
After adding 0 cc and reacting, it was determined by measuring an excess amount of di-n-butylamine by titration with hydrochloric acid using bromphenol blue as an indicator. This confirmed that the free isocyanate group was 0%. Regenerated isocyanate group (calculated as NCO) in the blocked isocyanate group-containing compound A was 6.8% by weight.

<Blocked Isocyanate Group-Containing Compound B>
40 parts of polyoxyethylene nonylphenol type nonionic surfactant (HLB = 15), which is an ethylene oxide adduct of distyrenated phenol, aqueous solution of polyvinyl alcohol (solid content 10%, partially saponified product, polymerization degree about 1,
000) 400 parts were added and mixed. Then, the mixture was stirred at high speed using a homomixer, and 750 parts of distilled water was gradually added therein to emulsify.

Then, ethyl acetate used as a solvent was recovered under reduced pressure by an evaporator.

Regenerated isocyanate groups (calculated as NCO) in the obtained blocked isocyanate group-containing compound B was 3.50% by weight.

<Blocked isocyanate group-containing compound C> Tolylene diisocyanate adduct of trimethylol propane (trimethylol propane: tolylene diisocyanate = 1: 3, diluted with ethyl acetate, solid content 75%, free isocyanate group 13.2) %) 500 parts was dissolved in 300 parts ethyl acetate, 180 parts ε-caprolactam was added, and the reaction was carried out using a mixed catalyst of dibutyltin dilaurate and triethylamine, and the free isocyanate group content was changed to the blocked isocyanate group-containing compound A. In the same manner as in the above case, it was confirmed that the free isocyanate group was 0%.

Then, 40 parts of polyoxyethylene nonylphenol type nonionic surfactant (HLB15), which is an ethylene oxide adduct of distyrenated phenol,
After 400 parts of a polyvinyl alcohol aqueous solution (solid content 10%, partially saponified product, degree of polymerization of about 1,000) was added, emulsification was performed while gradually adding 800 parts of distilled water under high speed stirring using a homomixer. Next, ethyl acetate used as a solvent was recovered under reduced pressure by an evaporator. The regenerated isocyanate group (calculated as NCO) in the obtained blocked isocyanate group C was 3.40% by weight.

(Preparation of heat-crosslinkable polyurethane emulsion composition) <Example 1> 350 parts of polyester polyol (butylene adipate, molecular weight 2,000), 10.1 parts of trimethylolpropane, 35 parts of polyethylene glycol (molecular weight 600), PO (Propylene Oxide) / EO
(Ethylene oxide) Random copolymerized polyether polyol 35 parts (PO / EO = 30/70, molecular weight 3,
400), 7,4-butanediol 78.3 parts, and isophorone diisocyanate 310 parts were reacted in methyl ethyl ketone using dibutyltin dilaurate as a catalyst to synthesize a urethane prepolymer. The free isocyanate group of the urethane prepolymer was 2.0% (relative to solid content).

Next, a polyoxyethylene arylphenol ether type nonionic surfactant (HLB = 1) which is an ethylene oxide adduct of distyrenated phenol.
5) After the addition of 80 parts, 1,300 parts of distilled water was gradually added while stirring at high speed using a homomixer to emulsify.

Next, an aqueous solution of diethylenetriamine in which 18 parts of diethylenetriamine was dissolved in 130 parts of distilled water was added and reacted. Next, the active amino group-containing polyurethane emulsion composition was prepared by recovering methyl ethyl ketone used as a solvent under reduced pressure with an evaporator. Then, by mixing 200 parts of the blocked isocyanate group-containing compound B and stirring,
A heat-crosslinkable polyurethane emulsion composition of Example 1 was obtained.

The obtained heat-crosslinkable polyurethane emulsion composition was analyzed. The results are shown in Table 1. The amount of active amino groups contained in the emulsion was calculated by carefully measuring 10 parts of the emulsion
-Methyl-2-pyrrolidone was dissolved in 300 parts, and determined by hydrochloric acid titration using bromphenol blue as an indicator. That is, the number of mg of KOH equimolar to the carboxyl group necessary for neutralizing 1 g of the sample was expressed as Am.V (amine value) (unit: KOHmg / g).

[0053]

[Table 1]

Example 2 Polyether polyol (P
O / EO polyaddition, PO / EO = 90/10, molecular weight 2,
000) 350 parts, trimethylolpropane 15 parts, polyethylene glycol (molecular weight 600) 30 parts, PO /
EO random copolymer polyether polyol (PO / E
40 parts of O = 30/70, molecular weight 3,600), 150 parts of cyclohexanedimethanol, and 360 parts of isophorone diisocyanate were reacted in methyl ethyl ketone using dibutyltin dilaurate as a catalyst to synthesize a urethane prepolymer. The free isocyanate group of the urethane prepolymer was 1.80% (relative to solid content).

Next, the same polyoxyethylene aryl phenol ether type nonionic surfactant (HL) as in Example 1 was used.
After adding 90 parts of B = 15), 1690 parts of distilled water was gradually added with high speed stirring using a homomixer to emulsify.

Next, an aqueous diethylenetriamine solution prepared by dissolving 18.7 parts of diethylenetriamine in 100 parts of distilled water was added and reacted. Next, the active amino group-containing polyurethane emulsion composition was prepared by recovering methyl ethyl ketone used as a solvent under reduced pressure with an evaporator. Then, 230 parts of the blocked isocyanate group-containing compound B was mixed and stirred to obtain a heat-crosslinkable polyurethane emulsion composition of Example 2.

Analysis of this heat-crosslinkable polyurethane emulsion composition was carried out. The results are shown in Table 1. The amount of amino groups contained was measured by the same method as in Example 1.

Example 3 Polycarbonate polyol (obtained by transesterification reaction of 1,6-hexanediol and dimethyl carbonate, molecular weight 2,0)
00) 255 parts, 7.0 parts of trimethylolpropane,
57.0 parts of 1,4-butanediol, 260 parts of isophorone diisocyanate, and dimethylolprobionic acid 2
By reacting 6.5 parts with methyl stannous octoate as a catalyst in methyl ethyl ketone to synthesize a urethane prepolymer, a urethane prepolymer containing a free isocyanate group and a carboxyl group was obtained. The content of free isocyanate groups was 1.99% (relative to solid content).

Next, 19.8 parts of triethylamine was added to neutralize the carboxyl group. Then, distilled water 900
Parts were gradually added and emulsified using a homomixer.

Next, an aqueous solution of diethylenetriamine, in which 13.3 parts of diethylenetriamine was dissolved in 80 parts of distilled water, was added at a system temperature of 25 ° C. to cause a reaction. To this solvent-containing emulsion, 100 parts of the blocked isocyanate group-containing compound A was mixed and stirred. Then, the heat-crosslinkable polyurethane emulsion composition of Example 3 was obtained by collecting under reduced pressure the methyl ethyl ketone and ethyl acetate used as the solvent with an evaporator.

The heat-crosslinkable polyurethane emulsion composition was analyzed and the results are shown in Table 1. The amount of amino groups contained was measured by the same method as in Example 1.

Example 4 The same procedure as in Example 1 was carried out except that 200 parts of the blocked isocyanate group-containing compound C was used instead of the blocked isocyanate group-containing compound B, and the thermal crosslinking of Example 4 was performed. A hydrophilic polyurethane emulsion composition was obtained.

The heat-crosslinkable polyurethane emulsion composition was analyzed and the results are shown in Table 1. The amount of amino groups contained was measured by the same method as in Example 1.

<Comparative Examples 1 to 3> An active amino group-containing polyurethane emulsion composition was obtained in the same manner as in Examples 1 to 3, and the polyurethane emulsion compositions of Comparative Examples were prepared without blending the blocked isocyanate group-containing compound. did.

These polyurethane emulsions were analyzed and the results are shown in Table 2.

The amino residues contained were measured in the same manner as in Example 1.

[0067]

[Table 2]

Comparative Examples 4 to 6 A urethane prepolymer was prepared and emulsified in the same manner as in Examples 1 to 3, and then ethylenediamine was added instead of adding diethylenetriamine used in Examples 1 to 3, respectively. The same molar amount was added, the mixture was stirred and mixed in the same manner as in Examples 1 to 3, and the solvent used was recovered to obtain polyurethane emulsions of Comparative Examples 4 to 6 according to the prior art in which the blocked isocyanate group-containing compound was blended. .

The polyurethane emulsions of Comparative Examples 4 to 6 were analyzed, and the results are shown in Table 2. The amount of amino groups contained was measured by the same method as in Example 1.

Comparative Example 7 In the same manner as in Example 1, a urethane prepolymer was prepared and emulsified. Thereafter, an aqueous solution of diethylenetriamine was added to this so that the molar ratio of (terminal NCO group of urethane prepolymer) / (amino group of diethylenetriamine) was 1.0 / 0.9, and the mixture was stirred and mixed as in Example 1. Then, the solvent used was recovered to obtain a polyurethane emulsion of Comparative Example 7 according to the prior art in which the blocked isocyanate group-containing compound was blended.

The polyurethane emulsion was analyzed and the results are shown in Table 2. The amount of amino groups contained was measured by the same method as in Example 1.

Comparative Example 8 By the same operation as in Example 1, instead of the blocked isocyanate group-containing compound A, sorbitol polyglycidyl ether (epoxy equivalent: 180 WP) was used.
30 parts of E) were compounded. The sorbitol polyglycidyl ether was blended so that the epoxy group contained therein and the regenerated isocyanate group in the blocked isocyanate group-containing compound A had the same number of moles. The polyurethane emulsion was analyzed and the results are shown in Table 2.

(Evaluation of Physical Properties of Coating Film) <Experimental Examples 1 to 8 and Comparative Experimental Examples 1 to 16> Examples 1 to 4
Also, the polyurethane emulsion compositions prepared in Comparative Examples 1 to 8 were applied to a Teflon coated plate and dried at room temperature for 3 days to obtain coating film samples of Experimental Examples 1 to 4 and Comparative Experimental Examples 1 to 8. In addition, after drying at room temperature, the temperature is 20 at 160 ° C.
What was heat-treated for minutes was Experimental Examples 5-8 and Comparative Experimental Example 9-
16 coating film samples were prepared.

Various physical properties of the coating film (thickness 100 μm) obtained above were measured, and the results are shown in Tables 3 and 4. Table 3 shows Experimental Examples 1 to 1 for coating film samples dried at room temperature.
4 and Comparative Experimental Examples 1 to 8 and Table 4 shows Experimental Examples 5 to 8 and Comparative Experimental Examples 9 to 16 for the coating film samples after the heat treatment.

Among the physical properties of the coating films shown in Tables 3 and 4, strength, elongation and 100% modulus (100% M
O) was measured at a pulling speed of 100 mm / min using a tensile tester (Autograph manufactured by Shimadzu Corporation) according to JIS-K-6301. Solvent resistance is determined by immersing a 2 × 4 cm coating film sample piece in a solvent of (ethyl acetate) / (toluene) = 1/1 (volume ratio) and then immersing the coating film sample area at 20 ° C. for 24 hours. It was measured by the swelling rate (%).
This swelling ratio is calculated by the following formula.

Swelling rate (%) = {(area after swelling-initial area) / (initial area)} × 100 Furthermore, the hot water resistance was determined by immersing a 2 × 4 cm coating film piece in hot water at 70 ° C. Then, the area swelling ratio (%) of the coating film sample piece after immersion at 70 ° C. for 24 hours was measured. This swelling ratio is obtained by the above formula.

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[Table 3]

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[Table 4]

From Tables 3 and 4, the heat-crosslinkable polyurethane emulsion compositions of Examples 1 to 4 clearly improve not only strength physical properties but also hot water resistance and solvent resistance by heat treatment. Recognize. It is considered that this is because the active amino group of the active amino group-containing polyurethane emulsion composition and the blocked isocyanate group of the cross-linking agent rapidly undergo a crosslinking reaction.

On the other hand, in the conventional polyurethane emulsions of Comparative Examples 4 to 7, even when the blocked isocyanate crosslinking agent is used together, a slight improvement in the physical properties of the coating film is recognized under the same heat treatment conditions. It is considered that this is because in the polyurethane emulsion according to the conventional technique, the physical property modification is left only to the self-polymerization of the blocked isocyanate crosslinking agent.

Claims (3)

[Claims] 1. A compound obtained by reacting a compound having two or more active hydrogen atoms with an organic polyisocyanate,
A urethane prepolymer having an isocyanate group at the molecular end is dispersed in water, and a polyamine having at least two or more active amino groups is added thereto, and the molar ratio of (terminal NCO group of urethane prepolymer) / (polyamine) is 1 /
A heat-crosslinkable polyurethane emulsion composition comprising an active amino group-containing polyurethane emulsion obtained by adding 1 or more and a blocked isocyanate group-containing compound. 2. The amine value (Am · V) per solid content of the active amino group-containing polyurethane emulsion is 5
(KOHmg / g) or more, The heat-crosslinkable polyurethane emulsion composition according to claim 1, which is characterized in that. 3. The active amino group-containing polyurethane emulsion is added with a blocked isocyanate group-containing compound at a molar ratio of (active amino group in the active amino group-containing polyurethane) / (regenerated isocyanate group) of 1/0.
The heat-crosslinkable polyurethane emulsion composition according to claim 1 or 2, wherein the heat-crosslinkable polyurethane emulsion composition is blended in a range of 5 to 1/2.