JPH11279242A - Aqueous resin composition curable with active energy ray, and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for simply producing an aqueous resin composition curable with active energy ray, completely free of solvent, giving a cured film excellent in properties (in particular flexibility), and excellent in storage stability. SOLUTION: This method produces (A) a polyurethane (meth)acrylate containing carboxylic group in the presence of (B) a water-soluble, reactive diluent mixed with 100 wt.% or more of water, converts the carboxyl group of the component A into an amine salt, and emulsifies the above product in the presence of water, in order to produce an aqueous resin composition curable with active energy ray.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active energy curable resin composition which is cured by active energy rays such as ultraviolet rays and electron beams. More specifically, the present invention relates to an aqueous active energy curable resin composition which is completely solvent-free and has excellent cured film properties, particularly flexibility, and is applicable to various uses having excellent storage stability. The aqueous active energy ray-curable resin composition of the present invention can be applied to various uses such as, for example, paper, overcoating agents for various plastic films, printing inks, and woodwork paints. In particular, the aqueous active energy ray-curable resin composition of the present invention is useful as a woodwork paint.

[0002]

2. Description of the Related Art A diol compound such as polyester diol and polyether diol, a diisocyanate compound such as isophorone diisocyanate and diphenylmethane diisocyanate, and a hydroxyl group-containing (meth) acrylate such as hydroxyethyl acrylate are used as main raw materials to obtain urethane. Polyurethane acrylate is known as an active energy ray-curable resin, and is widely used for applications such as woodwork paints.

[0003] Since such polyurethane acrylate generally has a high viscosity, it is used after being diluted with an organic solvent or a diluent such as a reactive diluent so as to have a low viscosity that can be applied. However, dilution with an organic solvent involves problems such as air pollution, working environment, and danger of fire. On the other hand, when diluting with a reactive diluent, a large amount is required for lowering the viscosity, and thus there is a problem that it is difficult to obtain sufficient cured film physical properties. From these circumstances,
There is a need for an active energy ray-curable resin composition that does not contain an organic solvent and does not contain a large amount of a reactive diluent.

[0004] As a countermeasure for the above-mentioned problems, various studies have been made on aqueous active energy ray-curable resin compositions. As a method of making the active energy ray-curable resin composition aqueous, a method using a water-soluble active energy ray-curable resin resin and a method of emulsifying and dispersing the active energy ray-curable resin resin are generally used. However, the water-soluble resin is limited in the structure of the resin in order to impart the ability to dissolve in water,
There is a problem that it cannot sufficiently cope with various uses. On the other hand, in the method of emulsification and dispersion, a self-emulsifying resin containing a carboxylate or a sulfonate is used. These self-emulsifying resins are usually organic solvents, especially acetone,
It is produced in a highly polar organic solvent such as a ketone solvent such as methyl ethyl ketone and an ester solvent such as ethyl acetate and butyl acetate, and the organic solvent is distilled off after emulsification. However, it is difficult to completely evaporate the solvent after emulsification, and it cannot be said that the above-mentioned problem has been solved because several percent of the organic solvent remains in the product. In addition, the number of steps for removing the solvent is increased as compared with the conventional case of diluting with an organic solvent or a reactive diluent.

As one of the solutions to the above-mentioned problem of the production process, a method of synthesizing an active energy ray-curable resin in the absence of a solvent has been attempted. difficult. For this reason, there is a problem that it is difficult to obtain sufficient physical properties of a cured film, particularly, flexibility. Also,
As another solution, for example, Japanese Patent Publication No. 5-28241 and Japanese Patent Application Laid-Open No. 7-292045 disclose that an active energy ray-curable resin is synthesized in the presence of a water-insoluble reactive diluent and then emulsified. A method is described. However, the active energy ray-curable resin synthesized by such a method is inferior in dispersion stability, and thus has a storage stability problem that the resin and the reactive diluent cause separation and sedimentation after emulsification.

[0006]

DISCLOSURE OF THE INVENTION In view of the above circumstances, the present invention is directed to water-active energy ray curing which is completely solvent-free and has excellent cured film properties, particularly flexibility, and excellent storage stability. An object of the present invention is to provide a simple method for producing a conductive resin composition.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, an aqueous active energy ray-curable resin composition comprising an emulsion obtained by the following method has been developed. And found that the present invention was completed.

That is, according to the present invention, a carboxyl group-containing polyurethane (meth) acrylate (A) is produced in the presence of a water-soluble reactive diluent (B) having a water miscibility of 100% by weight or more, and the (A) ) Polyurethane (meta)
A method for producing an aqueous active energy ray-curable resin composition, which further comprises adding water and emulsifying the acrylate group after converting the carboxyl group of the acrylate into an amine salt, and furthermore, the aqueous active energy ray-curable resin composition obtained by the above production method. It relates to a resin composition.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The carboxyl group-containing polyurethane (meth) acrylate (A) of the present invention comprises, for example, a polyol compound (a), an organic polyisocyanate compound (b) and at least one or more (meth) acryloyl groups. In the present invention, the (meth) acryloyl group means an acryloyl group and / or a methacryloyl group. Hereinafter, (meta) has the same meaning.反 応 and a compound (c) having at least one or more hydroxyl groups as a constituent, and the polyol compound (a) contains a polyol compound (d) having at least one or more carboxyl groups.

Examples of the polyol compound (a) include polyether polyols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol;
Polyester polyol, 1,4-butanediol,
Examples thereof include low molecular weight polyols such as 1,6-hexanediol and the like, ethylene oxide such as bisphenol A, and propylene oxide adducts, and these can be used alone or in combination.

The polyol compound (d) having at least one carboxyl group includes dimethylolpropionic acid, dimethylolbutanoic acid and the like.

The organic polyisocyanate compound (b) includes organic polyisocyanates having two or more reactive isocyanate groups in the molecule. A specific example is
1,6-hexane diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, trimers obtained from these diisocyanates, and polyhydric alcohols such as trimethylolpropane And polymethylene polyphenyl polyisocyanate, which can be used alone or in combination.

The compound (c) having at least one or more (meth) acryloyl groups and at least one or more hydroxyl groups is, for example, a hydroxyl group-containing (meth) acrylate, and specific examples thereof include 2-hydroxyethyl ( Hydroxyalkyl (meth) acrylates such as (meth) acrylate, 2-hydroxypropyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate, and ε of 2-hydroxyalkyl (meth) acrylate
-Polyol polyacrylates such as caprolactone condensate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, 2-hydroxyphenoxypropyl (meth) acrylate, pentaerythritol triacrylate, and polyepoxy acrylate; These can be used alone or in combination.

The use ratio of each component is not particularly limited, but the equivalent ratio of the hydroxyl group of the component (a) to the isocyanate group of the component (b) becomes (a) :( b) = 1: 1.2 to about 2. And the resulting carboxyl group-containing polyurethane (meth) acrylate (A) has an acrylic equivalent of 500 to 15
000 g / mol, and each component is appropriately adjusted so that the equivalent of the hydroxyl group of the component (c) is equal to or greater than the difference between the isocyanate group of the component (b) and the hydroxyl group of the component (a). Is preferred.

The component (d) contained in the component (a) is a carboxyl group-containing polyurethane (meth) obtained.
The acid value of the acrylate (A) is 15 to 40 mgKOH / g
It is preferable to use it after adjusting so as to fall within the range.
When the acid value of (A) is lower than 15 mgKOH / g, it is difficult to obtain an emulsion having good storage stability because the hydrophilicity of the resin is insufficient. On the other hand, when the acid value of (A) is higher than 40 mgKOH / g, the emulsion has a high viscosity, and only an emulsion having a low resin concentration can be obtained.

As a component of the carboxyl group-containing polyurethane (meth) acrylate (A), if necessary, a polyamine may be used as a chain extender. Hexamethylenediamine as a polyamine component,
Isophorone diamine and the like can be used.

Carboxyl group-containing polyurethane (meth)
In the production of the acrylate (A), each of the above components can be simultaneously reacted by batch charging. However, since the reaction can be easily controlled, first, an excess amount of isocyanate group equivalent to the hydroxyl group of the component (a) is used. b) react the components,
After forming the urethane prepolymer containing a terminal isocyanate group, it is preferable to react the component (c) with the terminal isocyanate group.

The reaction temperature is about 40 to 100 ° C., preferably 60 to 80 ° C., and the total reaction time is about 4 to 12 hours. The end of the reaction can be easily confirmed by quantifying the isocyanate residue by IR. In the urethanization reaction, it is preferable to use a known urethanization catalyst such as stannous octoate for promoting the reaction. In order to prevent polymerization of the component (c) during the urethanization reaction, a polymerization inhibitor such as hydroquinone, methoxyphenol, or phenothiazine is added to the reaction system in an amount of 10 to 500.
It is preferable to use 0 ppm, preferably 50 to 2000 ppm, or perform air sealing.

In the present invention, such a carboxyl group-containing polyurethane (meth) acrylate (A) is produced in the presence of a water-soluble reactive diluent (B) having a water miscibility of 100% by weight or more. With a reactive diluent having a water miscibility of less than 100% by weight, the stability of the emulsion after emulsification decreases, and resin sedimentation or separation occurs several days after emulsification. The “water mixing ratio” is a value expressed as a percentage of the number of parts by weight of water which can be mixed in a transparent state per 100 parts by weight of the water-soluble reactive diluent (B). Specific examples of such a water-soluble reactive diluent (B) include, for example, acryloylmorpholine, N-
Vinylformamide, N-vinylpyrrolidone, hexaethylene glycol di (meth) acrylate, nonaethylene glycol di (meth) acrylate, and the like,
These can be used alone or in combination.

The water-soluble reactive diluent (B) is used in an amount of usually about 5 to 50% by weight, preferably 10 to 30% by weight, based on 100 parts of the carboxyl group-containing polyurethane (meth) acrylate (A). % Or less. When the amount of the water-soluble reactive diluent (B) is less than 5% by weight, the viscosity during the urethanization reaction tends to be high and it is difficult to increase the molecular weight, and a cured film having sufficient flexibility cannot be obtained.
When the water-soluble reactive diluent (B) is more than 50% by weight,
The water resistance of the cured film tends to decrease significantly.

The addition timing of the water-soluble reactive diluent (B) is as follows:
The carboxyl group-containing polyurethane (meth) acrylate (A) may be added to the reaction system before the viscosity of the polyurethane (A) increases and stirring becomes impossible. Therefore, it may be present in the reaction system from the start of the reaction, or may be added to the reaction system during the reaction as long as the carboxyl group-containing polyurethane (meth) acrylate (A) has not been increased in viscosity yet.

The carboxyl groups of the polyurethane (meth) acrylate (A) thus obtained are neutralized into amine salts. Specific examples of the amine component used for neutralization include tertiary amines such as trimethylamine, triethylamine, methyldiethanolamine, dimethylethanolamine, diethylethanolamine, and triethanolamine. If the neutralization ratio of the carboxyl group is low, the hydrophilicity of the polyurethane (meth) acrylate (A) is insufficient, so that it is difficult to obtain an emulsion having good storage stability. Therefore, the neutralization ratio is preferably 70% or more. , Complete neutralization is particularly preferred. The neutralization of the carboxyl group may be performed during the production of the polyurethane (meth) acrylate (A), or may be performed after the production is completed.

Next, water is added to the polyurethane (meth) acrylate (A) in which the carboxyl group has become an amine salt and the water-soluble reactive diluent (B) to emulsify to obtain an emulsion. The emulsification method is not particularly limited, and may be performed by adding water while stirring these. However, if a large amount of water is added at a time, the polyurethane (meth) acrylate (A) becomes difficult to disperse, so it is preferable to add the water in several portions. In addition, as the solid content concentration of the obtained emulsion (hereinafter, the sum of (A) and (B) in the emulsion is referred to as solid content) decreases, it takes time to dry the water after coating. Since the viscosity of the emulsion is increased to be about 30% by weight or more and the solids concentration is increased, the solids concentration is 50% by weight.
The water is adjusted as appropriate so that the water content is not more than about 10 mL.

The aqueous active energy ray-curable resin composition of the present invention comprising the emulsion thus obtained does not require a photopolymerization initiator when the resin composition is cured by an electron beam or the like as an active energy ray. When the resin composition is cured by ultraviolet rays, the photopolymerization initiators 1 to 1 are usually added to 100 parts by weight of the resin composition.
About 5 parts by weight can be contained. Examples of the photopolymerization initiator include Darocure 1173 and Irgacure 65.
Various known materials such as 1, Irgacure 184, Irgacure 907 (all trade names, manufactured by Ciba Geigy), benzophenone and the like can be used. If necessary, various additives other than those described above, for example, polymerization inhibitors, antioxidants, ultraviolet absorbers, light stabilizers, defoamers, and leveling agents can be used. In some cases, pigments, silicon compounds, and the like may be contained according to the purpose without departing from the purpose of the present invention.

[0025]

According to the present invention, the composition has curability and cured film properties which are comparable to those of a non-aqueous active energy ray-curable resin composition, especially has flexibility, and is completely solvent-free and has storage stability. A water-based active energy ray-curable resin composition excellent in water resistance can be provided by a simple production process.

[0026]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. Hereinafter, "parts" and "%" are based on weight unless otherwise specified.

Example 1 In a flask equipped with a stirrer, a thermometer and a reflux condenser,
29 parts of dimethylolbutanoic acid and 253 parts of polytetramethylene glycol (molecular weight: 650) were charged. Then 1
Heat to 00 ° C to dissolve dimethylolbutanoic acid.
Cooled to 0 ° C. Isophorone diisocyanate 173
Parts, acryloyl morpholine 124 parts, hydroquinone monomethyl ether 0.5 part, the temperature was raised to 75 to 80 ° C., and after keeping it for 3 hours, 42 parts of 2-hydroxyethyl acrylate and 0.1 part of stannous octylate were added. In addition, the temperature was further maintained for 4 hours to obtain a polyurethane acrylate. After confirming disappearance of the isocyanate group by IR measurement, the mixture was cooled to 60 ° C., and neutralized by charging 20 parts of triethylamine. The product is deionized water 912
And an emulsion was obtained.

Example 2 In a flask equipped with a stirrer, thermometer and reflux condenser,
28 parts of dimethylolbutanoic acid and 262 parts of polypropylene glycol (molecular weight: 700) were charged. Then 100
℃ to dissolve dimethylolbutanoic acid
Cooled down. 167 parts of isophorone diisocyanate,
56 parts of acryloyl morpholine, 0.5 part of hydroquinone monomethyl ether were charged, the temperature was raised to 75 to 80 ° C., and after keeping the temperature for 3 hours, 44 parts of 2-hydroxyethyl acrylate and 0.1 part of stannous octylate were added, The temperature was further kept for 4 hours to obtain a polyurethane acrylate.
After confirming disappearance of the isocyanate group by IR measurement,
After cooling to 60 ° C., 20 parts of triethylamine was charged and neutralized. This product was charged with 1014 parts of deionized water to obtain an emulsion.

Example 3 An emulsion was obtained in the same manner as in Example 1 except that hexaethylene glycol diacrylate was used instead of acryloylmorpholine.

Comparative Example 1 An emulsion was obtained in the same manner as in Example 1 except that tetraethylene glycol diacrylate was used instead of acryloylmorpholine.

Comparative Example 2 An emulsion was obtained in the same manner as in Example 1 except that tripropylene glycol diacrylate was used in place of acryloylmorpholine, to obtain an emulsion. .

(Evaluation of Performance) The general properties of the emulsions obtained in the Examples and Comparative Examples, and the properties of the cured films obtained using the emulsions were measured and evaluated. These are shown in Table 1.
Shown in

(Polyurethane acrylate) Acid value: Conducted in accordance with JIS K 3504. Molecular weight: It is a weight average molecular weight (polystyrene conversion value) measured by GPC.

(Reactive diluent) Water mixing ratio (%): The number of parts by weight of water that can be mixed in a uniform and transparent state per 100 parts by weight of the reactive diluent is indicated by percentage. Addition amount (%): The ratio of the reactive diluent to the solid content was indicated by percentage.

(Properties of Emulsion) Neutralization ratio: The number of moles of the neutralized amine with respect to the number of moles of the carboxyl groups of the urethane acrylate was indicated by percentage. Solid content concentration (%): The total number of urethane acrylate and reactive diluent with respect to 100 parts of the emulsion was indicated by percentage. Viscosity: a value measured with an E-type viscometer (25 ° C.). pH: value measured at 25 ° C. Stability: The state after standing at 25 ° C. and 50 ° C. for one month was observed according to the following criteria. ：: No change in appearance. Δ: Transparency decreased. X: Resin settling.

(Measurement of physical properties of cured film) Preparation of varnish: 100 parts of the emulsions obtained in Examples and Comparative Examples were weighed into a beaker, and a photopolymerization initiator (Darocur 1173, manufactured by Ciba Geigy) was added to the solid content at 3 parts.
% And mixed and dissolved to prepare a varnish.

(Curability) The obtained varnish was 200 μm
Is applied on a glass plate with an applicator, and dried in a circulating drier at 80 ° C. for 2 minutes.
The curability was measured by changing the irradiation dose under the conditions of cm (one lamp) and irradiation distance of 10 cm.

(Elongation, strength) Curability test (irradiation dose 26
The elongation and strength were measured using the cured film obtained at 0 mJ / cm ² ). Test piece: width 6mm, length 5cm (distance between chucks 2.5
cm) Elongation: Elongation was performed at a tensile speed of 50 mm / min, and the elongation relative to the self-length at break was measured. Strength: tensile strength was measured at a tensile speed of 50 mm / min, and the stress at break was measured.

(Water resistance) Curability test (irradiation dose 260m
(J / cm ² ), deionized water was dropped on the surface of the cured film obtained, the lid was covered, and the appearance change after 24 hours was examined. ：: No change. Δ: Swelling. X: Torn and dissolved.

[0040]

【table 1】

In the table, ACMO: acryloyl morpholine, 6 EGA: hexaethylene glycol diacrylate, 4 EGA: tetraethylene glycol diacrylate, TPGDA: tripropylene glycol diacrylate are shown.

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Claims (3)

[Claims] 1. A carboxyl group-containing polyurethane (meth) acrylate (A) is produced in the presence of a water-soluble reactive diluent (B) having a water miscibility of 100% by weight or more, and the polyurethane (A) After converting the carboxyl group of the (meth) acrylate to an amine salt, water is further added,
A method for producing an aqueous active energy ray-curable resin composition, comprising emulsifying. 2. An aqueous active energy ray-curable resin composition obtained by the production method according to claim 1. 3. The aqueous active energy ray-curable resin composition according to claim 2, which contains a photopolymerization initiator.