JPH09165432A - Aqueous isocyanate dispersion and curing composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aqueous isocyanate dispersion having excellent storage stability by using a polymeric dispersant comprising a copolymer containing units of a monomer which can give a homopolymer having a specified solubility parameter and a specified HLB, and units of a hydrophilic-group-containing monomer. SOLUTION: Ten (10) to 60wt.% aromatic-group-containing monomer (e.g. styrene) which can give a homopolymer having a solubility parameter of 10.0 or above and an HLB of 12 or below is copolymerized with 10-75wt.% hydrophilic-group-containing monomer (e.g. acrylic acid) and other monomers in an organic solvent, ammonia water is then added to the reaction mixture, and the solvent is removed from the mixture to obtain a polymeric dispersant (e.g. aqueous acrylic solution). Next, an organic polyisocyanate and about 3-150wt.% polymeric dispersant are dispersed in water to obtain an aqueous isocyanate dispersion. This aqueous isocyanate dispersion is mixed with an isocyanato-reactive active-hydrogen-containing resin (e.g. hydroxyethyl (meth) acrylate copolymer) in a weight ratio of about (1-50)/(50-99) (in terms of the solid matter) to obtain a curing composition.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an aqueous dispersion which can be used as a cross-linking agent for an aqueous resin or a one-component curable resin. More specifically, the present invention relates to an isocyanate aqueous dispersion containing a free isocyanate group stably for a long period of time either alone or in the presence of an isocyanate-reactive active hydrogen group-containing substance.

[0002]

2. Description of the Related Art Aqueous isocyanate crosslinking agents have been used in water-based adhesives, coating agents, fiber treatment agents and the like for the purpose of imparting water resistance, solvent resistance and the like. Among the cross-linking agents, one that is stable in one liquid is, for example, an organic polyisocyanate and an isocyanate-capturing polymer which are dispersed in a non-aqueous solvent with a dispersion stabilizer having an affinity portion for the polymer and a hydrophobic solvent affinity portion. A technique of dispersing the particles thus obtained in water (Japanese Patent Laid-Open No. 62-13425, etc.) has been proposed.

[0003]

However, since the above technique has many components and is complicated, and the isocyanate content (concentration) in the dispersion is low, it is necessary to use a large amount when used as a crosslinking agent. However, the use of the resin is restricted because the physical properties of the crosslinked resin are impaired.

[0004]

The present inventors have made it possible to stably disperse the free isocyanate group of an organic polyisocyanate compound in water at a high concentration, and to keep it at room temperature or higher for a long time even in the presence of an isocyanate-reactive active hydrogen-containing substance. The present invention has been achieved as a result of extensive studies on a method of stably existing over the entire range. That is, the present invention provides an isocyanate water dispersion in which an organic polyisocyanate compound (A) is stably dispersed in water in the presence of a polymer dispersant (B), and the (B) has a solubility parameter (SP
Value) 10.0 or more and an HLB value of 12 or less, which is a copolymer having a unit composed of a monomer (b1) giving a homopolymer and a unit composed of a hydrophilic group-containing monomer (b2) as essential constituent units. The present invention relates to an isocyanate water dispersion, and a curable composition containing the isocyanate water dispersion as a crosslinking agent. The SP value is calculated by the Fedors method [Polym. En
g. Sci. 14 (2) 152, (1974)], and the HLB value is calculated by Oda method [Oda and Terada, “Synthesis of surfactants and their applications”, page 501, Maki Shoten (1957)]. Is the value to be set.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Examples of the organic polyisocyanate compound (A) used in the present invention include isocyanate monomers [(aromatic isocyanate: tolylene diisocyanate, diphenylmethane diisocyanate, etc.), (aromatic aliphatic isocyanate: p- Xylylene diisocyanate, α, α, α ′, α′-tetramethyl xylylene diisocyanate, etc.), (alicyclic isocyanate: isophorone diisocyanate, dicyclohexylmethane diisocyanate, etc.), (aliphatic isocyanate: hexamethylene diisocyanate, dodecamethylene Diisocyanate, etc.)]; Modified products of these isocyanate monomers (isocyanurate, burette, uretdione, trimethylolpropane adduct, etc.); Isocyanate prepoly Mer (for example, a reaction product of a hydrophobic polyol and an excess isocyanate compound); an isocyanate polymer (diphenylmethane diisocyanate polymer, etc.) and a mixture of two or more thereof. Preferred of these are:
And and particularly preferred are and. When (A) has a high viscosity, a hydrophobic solvent such as heptane, cyclohexane or xylene may be used as a viscosity reducing agent.

The polymer dispersant (B) has an SP value of 10.0.
A copolymer having the above unit and a unit consisting of a monomer (b1) giving a homopolymer having an HLB value of 12 or less and a unit consisting of a hydrophilic group-containing monomer (b2) as essential constitutional units, wherein (b1) is , Aromatic group-containing monomers [styrene, α-methylstyrene, polystyrene glycol (meth) acrylate, phenoxy (poly)
Oxyalkylene (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, N
-(4-anilinophenyl) (meth) acrylamide and the like]; blocked isocyanate group-containing monomer [m-
Isopropenyl-α, α-dimethylbenzyl isocyanate methylethylketoxime block, etc.];
Examples thereof include heterocycle-containing monomers [morpholinoethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, etc.]. Of these, preferred are the ones in terms of affinity for (A) and mixtures thereof.

As (b2), anionic monomers [(meth) acrylic acid, itaconic acid, (meth) acryloyloxypolyoxyalkylene sulfate, alkylallylsulfosuccinic acid and neutralized salts thereof]; cations , A nonionic monomer [polyethylene glycol (meth) acrylate, methosipolyoxyethylene (meth) acrylate, etc.] and the like. Preferred of these are and mixtures with any of these.

As the monomer constituting the (B), other monomers [alkyl (meth) acrylate and the like] may be optionally contained in addition to the above (b1) and (b2).

The isocyanate-reactive active hydrogen-containing substance (C) constituting the curable composition of the present invention is a water-soluble or water-dispersible aqueous resin containing active hydrogen groups such as hydroxyl group, carboxyl group and amino group. Is included. Examples of such an aqueous resin include (meth) acrylic polymers [hydroxyethyl (meth) acrylate copolymers, hydroxypropyl (meth) acrylate copolymers, etc.]; vinyl polymers (vinyl acetate copolymers) Olefin polymers (ethylene-vinyl acetate copolymers, propylene polymer hydroxyethyl acrylate grafts, etc.); ester polymers (vegetable fats and oils-dibasic acid-glycol condensation polymers, aromatics) Group dibasic acid-aliphatic dibasic acid-glycol condensation polymer);
Epoxy polymer (bisphenol-epichlorohydrin condensation polymer, etc.); Urethane polymer (diisocyanate-glycol-polyhydric alcohol adduct, polyurethane resin containing carboxyl group or amine salt thereof in the molecule, isocyanate group-terminated urethane prepolymer Alkanolamine blocked products); cellulosic polymers (starch, CMC, etc.); and mixtures of two or more thereof.

The number average molecular weight of the (B) is usually at least 2500, preferably at least 5000. If the number average molecular weight is less than 2500, sufficient dispersion stability may not be obtained. The amount of (b1) constituting the (B) is
It is usually 10 to 60% by weight, preferably 20 to 40% by weight, based on the weight of (B). If the amount of (b1) is less than 10% by weight or more than 60% by weight, a stable aqueous dispersion cannot be obtained. Further, the amount of (b2) constituting (B) is
It is usually 10 to 75% by weight, preferably 20 to 70% by weight, based on the weight of (B). If the amount of (b2) is less than 10% by weight or more than 75% by weight, a stable aqueous dispersion cannot be obtained.

The amount of (B) in the aqueous isocyanate dispersion of the present invention is usually at least 5 based on the weight of (A).
% By weight, preferably at least 10% by weight.
If the amount of (B) is less than 5% by weight, the dispersion stability of (A) may be insufficient.

The solid content weight ratio of the isocyanate dispersion and the active hydrogen-containing resin (C) in the curable composition of the present invention is usually (1-50) :( 50-99), preferably (3-30): (70 to 97). When the ratio of the isocyanate dispersion is less than 1, a sufficient crosslinking effect (film durability, etc.) cannot be obtained, and when it exceeds 50, the cured film may be hard and brittle.

The method for producing the isocyanate aqueous dispersion of the present invention is not particularly limited, but, for example, (A)
And an aqueous solution containing (B) are collectively mixed and dispersed; a method in which (A) is dropped and mixed and dispersed in an aqueous solution containing (B); an aqueous solution containing (B) is dropped and mixed in (A) Examples include a method of dispersing. As a method of dispersing, for example, a method of forcibly dispersing using a high speed stirrer can be mentioned.

The aqueous isocyanate dispersion of the present invention is a colloidal dispersion, and the isocyanate groups are stably retained for a long period of time. That is, when dispersed in water, (A) forms fine particles surrounded by (B),
Isocyanate groups are blocked from active hydrogen and are stably retained, but when water volatilizes, the particles are destroyed and a reaction occurs with the active hydrogen in the mixed resin (C) or on the surface of the base material, etc. Develops the original properties of polyisocyanate.

The method for mixing the isocyanate aqueous dispersion and the aqueous solution or dispersion of the active hydrogen-containing resin (C) in the curable composition of the present invention is not particularly limited. For example, (C)
A solution or an aqueous dispersion and an isocyanate dispersion of
It can be mixed using a usual stirring and mixing device (anchor type, propeller type, etc.).

[0016]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. still,
In the following, "part", "%" and "ratio" are based on weight.

The abbreviations of the raw materials used in the examples and comparative examples have the following meanings. [Organic polyisocyanate (A) component] IPDI-N: isocyanurate modified product of isophorone diisocyanate ["IPDI-T187 manufactured by Huls"]
0 "] HDI-N: isocyanurate-modified hexamethylene diisocyanate [" Coronate EH "manufactured by Nippon Polyurethane Industry] HDI-T: trimethylolpropane 3 mol adduct of hexamethylene diisocyanate [" Coronate HL "manufactured by Nippon Polyurethane Industry] Deethyl acetate product of [Polymer dispersant (B) component] B1: 2-Hydroxy-3-phenoxypropyl acrylate [“Aronix M5700” manufactured by Toagosei Kagaku]
/ Metacloyloxypolyoxypropylene sulfate sodium salt ["Eleminol RS-30" manufactured by Sanyo Chemical Industries]
Random copolymerization copolymer [copolymerization ratio = 50/50,
Number average molecular weight of about 20,000] B2: N- (4-anilinophenyl) -methacrylamide [Seiko Chemical's "APMA"] / lauryl methacrylate / methacryloyloxypolyoxypropylene sulfate sodium salt random copolymer [copolymer Ratio = 25 /
25/50, number average molecular weight of about 20,000] B3: 2-hydroxy-3-phenoxypropyl acrylate / lauryl methacrylate / methacrylic acid triethylamine salt random copolymer [copolymerization ratio =
40/40/20, number average molecular weight of about 10,000] B4: 2-hydroxy-3-phenoxypropyl acrylate / lauryl methacrylate / methacrylic acid trimethylamine salt / polyethylene glycol methacrylate [NOF CORPORATION “Blenmer PE-350”] Polymerization copolymer [copolymerization ratio = 35/35/15/1
5, number average molecular weight about 10,000] B5: styrene graft copolymer of lauryl methacrylate / triethylamine methacrylate random copolymer [copolymerization ratio = 65/20/15, number average molecular weight about 2]
Ten thousand]

Examples 1 to 5 A 15% aqueous solution of a polyisocyanate compound and a polymer dispersant shown in Table 1 was charged into a 300 ml beaker, and a rotor stator type disperser (Ultra Disperser LK-22 was used.
Type at YAMATO Co., Ltd.
The dispersion was carried out at 00 RPM for 5 minutes to obtain an isocyanate aqueous dispersion of the present invention. A storage stability test was performed on the obtained dispersion according to the following method. Storage stability test: NCO immediately after production of the obtained aqueous dispersion
Based on the content (% by weight), the retention rate of the NCO content was calculated from the measurement results of the NCO content after 1 day, 10 days and 30 days of the aqueous dispersion stored at 40 ° C. Further, the average SP value of the homopolymer of the copolymerization monomer (b1) of the polymer dispersant used was calculated by the Fedors method, and the HLB value was calculated by the Oda method. Table 2 shows the results.

Comparative Example 1 Based on the description of Example 1 in JP-A-62-13425, a comparative isocyanate aqueous dispersion having the following constituent ratios was prepared and its stability test was conducted. The results are shown in Table 2. (Component ratio of dispersion) Hexamethylene diisocyanate modified product: 3.7 parts (Asahi Kasei Kogyo's "Duranate 24A100") Styrene / butadiene block copolymer: 1.2 parts (Asahi Kasei's "Tafprene A") Styrene / Acrylonitrile (4/6) copolymer: 8.0 parts Cyclohexane: 24.0 parts Maleic anhydride / vinyl ether copolymer: 1.3 parts (Gaflet "Gantret AN-169") Emulsifier 1 (Daiichi Kogyo) "Neugen ES-120" manufactured by Pharmaceutical Company): 13.0 parts Emulsifier 2 ("Nonipol 140" manufactured by Sanyo Chemical Industry Co., Ltd.): 1.3 parts Water: 47.5 parts

[0020]

[Table 1]

[0021]

[Table 2]

Examples 6 to 10 A 2 L reactor equipped with a nitrogen gas blowing tube, a dropping funnel, a thermometer, a cooling tube and a stirrer was charged with 368 parts of methyl ethyl ketone and heated to 80 ° C. under a nitrogen gas atmosphere. The monomer mixture solution was subjected to dropwise polymerization over 3 hours, and further aged for 1 hour at the same temperature. (Monomer mixture solution composition) Acrylic acid 35 parts Methyl methacrylate 115 parts Butyl acrylate 35 parts 2-Hydroxyethyl acrylate 65 parts Styrene 100 parts Azoisobutyronitrile 18 parts The resulting acrylic resin solution is cooled to 60 ° C. 28%
After 30 parts of ammonia water and 733 parts of water were added and mixed, methyl ethyl ketone was distilled off under reduced pressure at 60 ° C. to obtain an acrylic resin aqueous solution having a hydroxyl value of 85 per resin content and a solid content of 35%. The resin aqueous solution and the isocyanate aqueous dispersions obtained in Examples 1 to 5 were mixed at the compounding ratios shown in Table 3 (OH / NCO equivalent ratio = 1/1) to obtain the curable compositions of the present invention. It was The composition was sealed and stored at 40 ° C. for 1 month, and the NCO content was measured after 1 day, 10 days and 30 days. Table 3 shows the results.

Comparative Example 2 100 parts of the above acrylic resin aqueous solution was mixed with 278 parts of the isocyanate water dispersion of Comparative Example 1 (OH / NCO equivalent ratio = 1/1) to obtain a comparative curable composition. The comparative composition was sealed and stored at 40 ° C. for 1 month, and the NCO content was measured after 1 day, 10 days and 30 days. The results are also shown in Table 3.

[0024]

[Table 3]

Performance Test Examples The curable compositions of the present invention of Examples 8-14 and Comparative Example 2
The curable composition of (1) is coated on a white coated steel sheet with an applicator (dry film thickness 20 to 30 μm), and cured under the conditions shown in Table 4 (left at room temperature for 5 days or heated at 60 ° C. for 30 minutes), The performance of the coating film was evaluated by the following test method. Table 4 shows the results. (Film coating test method) Hardness: Pencil hardness (using Mitsubishi Uni-Pencil) Solvent resistance: Xylene rubbing 20 times Evaluation standard ○; No abnormality ×; Dissolution Water resistance: Film after immersion in warm water at 80 ° C for 5 hours Condition evaluation criteria ○: No abnormality ×: Whitening Adhesion: Cross-cutting method (2 mm square, 25 pieces of cellophane tape peeling) Evaluation criteria ○; 25/25 ×; 0-5 / 25

[0026]

[Table 4]

[0027]

The isocyanate aqueous dispersion of the present invention has the following effects. (1) It has a very good storage stability in a water-dispersed state even though it contains a high concentration of free isocyanate groups. (2) The original function of polyisocyanate is easily exhibited by evaporation of water at room temperature or by heating. (3) Since it is water-based, handling is easy and safety is high. (4) A film obtained by curing a compound with an active hydrogen-containing aqueous resin exhibits excellent film properties such as solvent resistance, flexibility, acid resistance, and adhesion to various substrates. From the above effects, the isocyanate water dispersion of the present invention is, for example, a building material (glass, slate, ceramics-based inorganic material, aluminum or other metal material, wood, plastic material, etc.)
Interior and exterior paints for vehicles, vehicles (top coat, top coat, middle coat,
Undercoat, etc.) paints, vehicle parts paints, chipping paints,
Plastic paints, acid rain resistant paints, anticorrosive paints, hard coating agents, can coating agents, PVC sheet coating agents, paper coating agents, various coatings (coating agents) for plastic film primers, textile treatment agents, etc. , It is extremely useful as a cross-linking agent for adhesives (adhesives for lamination, etc.).

Claims (4)

[Claims] 1. An isocyanate water dispersion in which an organic polyisocyanate compound (A) is stably dispersed in water in the presence of a polymer dispersant (B), wherein the (B) has a solubility parameter (SP). Value) 10.0 or more and HLB value 1
An isocyanate water dispersion, which is a copolymer having a unit consisting of a monomer (b1) giving a homopolymer of 2 or less and a unit consisting of a hydrophilic group-containing monomer (b2) as essential constituent units. 2. The amount of (b1) constituting (B) is (B)
The isocyanate aqueous dispersion according to claim 1, wherein the weight of (b2) is 10 to 75% by weight, and the weight of (b2) is 10 to 75% by weight, based on the weight of (B). 3. The aqueous isocyanate dispersion according to claim 1, wherein the amount of (B) is 3 to 150% by weight based on the weight of (A). 4. A curable composition comprising the isocyanate water dispersion according to claim 1 and an aqueous solution and / or water dispersion of an isocyanate-reactive active hydrogen-containing resin (C).