JPH07138528A - Radiation-curable coating composition - Google Patents

Abstract

PURPOSE:To obtain the compsn. which does not contain a large amt. of an org. solvent, can form a network structure, and gives a coating film which is not brittle and adheres well to a substrate. CONSTITUTION:The compsn. is obtd. by reacting an emulsion of a polyurethane having active amino groups with a polymerizable unsatd. isocyanate compd. to give an aq. dispersion of a radiation-curable polyurethane having polymerizable unsatd. groups and adding a photosensitizer to the dispersion. Because of the polymerizable unsatd. groups of the radiation-curable polyurethane the compsn. can form a dense network structure while it is an aq. dispersion not contg. a large amt. of an org. solvent, giving a coating film which is not brittle and adheres well to a substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation curable coating composition which is polymerized by irradiation with various kinds of radiation.

[0002]

2. Description of the Related Art Polyurethane resin is a useful material which has been used in a wider range of applications than before, and one of the applications is a coating composition. Conventionally, a coating composition using a solvent has been widely used. However, it has been pointed out that this solvent composition has a problem in that the environment is polluted by the dispersion of the solvent used in the atmosphere and is harmful to the human body. As a solution to this problem, water-soluble or water-based emulsion type synthetic resins have recently been rapidly regarded as beneficial, and the amount of use thereof is expanding toward the future.

As a water-soluble or water-based emulsion resin used in a coating composition, there is a polyurethane resin, and one of them is a relatively low to medium molecular weight heat-reactive polyurethane emulsion having a blocked isocyanate group. . Another example is a polyurethane emulsion having a relatively high molecular weight region mainly composed of a linear structure having no reactive group.

The polyurethane in these emulsions should be dispersed in water after self-emulsification and dispersibility is imparted by introducing hydrophilic groups such as anionic, cationic and nonionic into the urethane resin skeleton. Alternatively, an emulsifier is added to a hydrophobic urethane resin and forcibly dispersed in water.

On the other hand, in recent years, radiation curable resins which are polymerized by various kinds of radiation such as ultraviolet rays and electron beams have the advantages of energy saving, processing at low temperature and in a short time, and therefore show rapid growth especially in the paint industry. ing. Among these conventional radiation curable resins, non-aqueous type resins are predominant. Since these are directed to energy saving, low temperature, and short-time processing as described above, 100% of the constituents are composed of resin components, and the mainstream of them is radiation curable resin in the medium molecular weight range and coating suitability. It contains a large amount of low molecular weight monomer components for improving viscosity adjustment, namely so-called reactive diluent monomers. Examples of the reactive diluent monomer include vinyl acetate, vinylpyrrolidone, alkyl acrylic ester and the like.

[0006]

However, the conventional water-soluble or water-based polyurethane emulsion coating composition described above has the following problems. That is, in the case of a relatively low to medium molecular weight heat-reactive polyurethane emulsion having a blocked isocyanate group, it is necessary to treat at a temperature higher than the temperature at which the blocking agent dissociates, and the heat resistance of the adherend material becomes a problem. , The scope of application is limited.

Further, in the case of a polyurethane emulsion in a relatively high molecular weight range mainly composed of a linear structure having no reactive group, for example, the performance such as heat resistant adhesive property, solvent resistance, chemical resistance, etc. is poor and its improvement is improved. Is currently desired. Further, in order to improve various drawbacks of these conventional polyurethane emulsions, it has been attempted to blend various melamine-based crosslinking agents such as trimethylolmelamine, epoxy-based and blocked isocyanate-based crosslinking agents. As a result, although some improvement in performance has been recognized, most of them are still insufficient in performance. In addition, when these crosslinking agents are added and crosslinked, it is possible to form a film at the temperature required for drying and to exhibit good physical properties, for example, because a treatment temperature higher than the reaction temperature of the reactive group of the crosslinking agent is required. The advantages of conventional polyurethane emulsions are diminished. Further, considering the heat resistance of the adherend material, the processing conditions are restricted and the applicable range is limited. Therefore,
The reality is that a satisfactory coating composition has not yet been developed.

This lack of performance is mainly due to the fact that the polyurethane contained in the above-mentioned prior art coating composition does not have a functional group capable of crosslinking. That is, it is considered that the conventional modification with these crosslinking agents is at the level of improving the physical properties by the entanglement such as the interpenetrating network (IPN) between the polyurethane resin and the self-polymer of these crosslinking agents. Therefore, a polyurethane emulsion coating composition having a function of forming a network structure which improves the physical properties of a coating film in the prior art is eagerly desired, and its presence is beneficial.

On the other hand, in a coating composition using a radiation curable resin according to the prior art, a low molecular weight reactive diluting monomer for adjusting viscosity and film thickness is added in an amount of 20 to 70 parts by weight. Since it needs to be added to the molecular weight resin component,
The addition of this reactive diluting monomer causes a problem in safety control, and also causes a problem of odor pollution because it is harmful to the human body.

Further, the coating composition containing a large amount of these low molecular weight reactive diluent monomers in combination has the following problems. Many of the films or coatings that have been coated by curing have an odor characteristic of the starting resin, which is mainly due to the reactive diluent monomer. This odor is a very troublesome problem. The excellent flexibility of the coating film obtained by using the radiation curable resin in the medium molecular region which is the main agent is remarkably impaired and the coating film tends to become brittle. Since the curing shrinkage caused by the low-molecular-weight reactive diluent monomer generated during the polymerization is remarkable, there is a problem that poor adhesion between the coating film and the adherend is likely to occur.

In order to reduce or completely eliminate the above-mentioned drawbacks, it is an important subject to carry out chemical and industrial treatments. A simple method to solve this problem is to reduce the amount of reactive diluent monomer used by adding water, but since the radiation-curable resin in the prior art is insoluble in water, a small amount of water is used. Although it can be used and compounded, it cannot be compounded in a large amount and cannot be fundamentally solved. As a chemical method for solving this point, it is the current situation that the radiation curable resin is made water-based.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to have a function of forming a net-like structure, and to provide adhesion to an adherend, heat resistance and water resistance. It is to provide a radiation curable coating composition having good physical properties such as.

[0013]

The radiation-curable coating composition of the present invention is a radiation-curable composition obtained by adding a polymerizable unsaturated group-containing isocyanate compound to an active amino group-containing polyurethane emulsion in the presence of water to cause a reaction. It is characterized by containing a curable polyurethane aqueous dispersion and a photosensitizer.

The active amino group-containing polyurethane emulsion is obtained by emulsifying and dispersing in water a urethane prepolymer having an isocyanate group at the molecular end, which is obtained by reacting a compound containing two or more active hydrogens with an organic polyisocyanate. Then, it is obtained by adding and reacting a polyamine having at least two primary amino groups and at least one secondary amino group in the same molecule.

Furthermore, when the polyamine is added to the urethane prepolymer, the molar ratio of (terminal NCO group of the urethane prepolymer) / (primary amino group of the polyamine) is 1/1 to 1 / 0.7. It is preferable to carry out so as to be within the range.

The polymerizable unsaturated group-containing isocyanate compound has a (meth) acryloyl group in the same molecule,
It can be a compound containing at least one group selected from the group consisting of an allyl group and a styrene group and at least one isocyanate group.

Further, the ratio of (the number of moles of the active amino group of the polyurethane emulsion containing the active amino group) / (the number of moles of the isocyanate group of the isocyanate compound containing the polymerizable unsaturated group) is 1 / 1.05 to 1 / It can be a ratio of 0.8.

The radiation-curable coating composition of the present invention can be obtained by adding a reactive unsaturated group-containing isocyanate to the active amino group-containing polyurethane emulsion and reacting it as described above. The preparation of the emulsion facilitates the introduction of the polymerizable unsaturated group into the urethane skeleton. The active amino group-containing polyurethane emulsion is obtained by reacting a urethane prepolymer having an isocyanate at the molecular end with a polyamine having at least two primary amino groups and at least one secondary amino group in the same molecule. To be The production of a urethane prepolymer having an isocyanate group at the molecular end is carried out in a system in which a compound containing two or more active hydrogens and an organic polyisocyanate are in excess.

The above-mentioned compound containing two or more active hydrogens is a compound containing two or more hydroxyl groups at the terminal or in the molecule, and is a generally known polyether, polyester, polycarbonate, polyetherester, polythioether, Examples thereof include polyol compounds such as polyacetal, polybutadiene, and polysiloxane. The molecular weight of the compound containing two or more active hydrogens is 30.
It is preferably in the range of 0 to 5,000. If necessary, low molecular weight 1,4-butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, ethylene glycol, butanediol, neopentyl glycol, diethylene glycol, trimethylolpropane, cyclohexane. Glycol such as dimethanol or triol may be used.

As the organic polyisocyanate compound, an aromatic, aliphatic or alicyclic organic polyisocyanate which has been conventionally used is used. For example, organic polyisocyanates such as tolylene diisocyanate, diphenyl methane diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, dicyclohexyl methane diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, tetramethyl xylylene diisocyanate or mixtures thereof. Can be given.

The reaction between the compound containing two or more active hydrogens and the excess amount of the organic polyisocyanate is carried out by a conventionally known one-step or multi-step isocyanate polyaddition reaction method under the temperature condition of 50 to 120 ° C. Be seen.

In this reaction, if necessary, a reaction control agent such as phosphoric acid, adipic acid, benzoyl chlorite, a reaction catalyst such as dibutyltin dilaurate, stannas octoate, triethylamine, and an organic solvent that does not react with an isocyanate group. May be added during or after the reaction. Examples of these organic solvents include acetone, methyl ethyl ketone, tetrahydrofuran, dioxane, ethyl acetate, toluene and xylene.

Although it is possible not to use an organic solvent at all, when the urethane prepolymer is used for dilution due to its high viscosity, after preparation of the active amino group-containing polyurethane emulsion described below or the active amino group-containing polyurethane. After the reaction between the emulsion and the isocyanate compound containing a polymerizable unsaturated bond is completed, it can be recovered under reduced pressure.

Considering the concern about the polymerization of the polymerizable unsaturated group due to the recovery under reduced pressure, the solvent is recovered after the preparation of the active amino group-containing polyurethane emulsion, that is, before the introduction of the polymerizable unsaturated group into the polyurethane skeleton. Preference is given to carrying out in process.

If desired, a stabilizer such as an antioxidant may be added during the reaction or after the reaction. The content of the isocyanate group at the terminal of the urethane polymer is 3.0 to 0.3% by weight, more preferably 2.
It is desirable to set it to 0 to 1.0%. When the content of the terminal isocyanate group is more than 3.0% by weight, the emulsion is destroyed during the reaction with the polyamine described below to cause gelation, or the product stability and the temporal stability become poor, and the content of the terminal isocyanate group is 0. If the amount is less than 3% by weight, the amount of the active amino group introduced by the polyamine described below will be small, and as a result, the amount of the polymerizable unsaturated group-containing isocyanate introduced in the reaction of the subsequent step will be small and will be introduced into the urethane skeleton. The amount of polymerizable unsaturated groups to be used is reduced. Therefore,
It cannot be expected to improve the physical properties of the coating film after radiation curing of the radiation curable polyurethane emulsion in the present invention.

The urethane prepolymer having an isocyanate group at the molecular end is emulsified and dispersed in water. The method is as follows. ． In the above-mentioned urethane prepolymer preparation step, a polyol component containing a carboxyl group in the molecule in advance, for example, a carboxyl group has been introduced by a reaction between dimethylolpropionic acid and the like and an organic polyisocyanate, and the carboxyl group is triethylamine, trimethylamine, A method in which a basic compound such as diethanol monomethylamine, diethylethanolamine, caustic soda, or caustic potassium is neutralized to convert to a carboxyl group salt.

.. In the above-mentioned urethane prepolymer preparation step, a nonionic activator having an oxyethylene chain content of 5 to 20% by weight in the molecule and an HLB value of 6 to 18 is added at 50 ° C. or lower after preparation of the urethane prepolymer. How to mix. However, the amount of this activator used is emulsifying and dispersing,
Considering the water resistance of the product film, it is preferably 2 to 15% by weight based on the urethane prepolymer.

.. After the above urethane prepolymer preparation,
50 to 5% of the terminal isocyanate groups is more preferable, and 3
Aqueous solution of sodium ethane such as aminoethanesulfonic acid, aminoacetic acid, etc. corresponding to 0 to 5%, potassium salt solution at 5 to 50 ° C.
Preferred is a method of reacting at 20 to 40 ° C. for 60 minutes. If the urethane prepolymer is self-dispersible in water, the above-mentioned hydrophilization is not necessary.

After performing any of the above operations,
Water is added and emulsified and dispersed using an emulsifying and dispersing device such as a homomixer and a homogenizer. When emulsifying and dispersing, in order to suppress the reaction between the terminal isocyanate group of the urethane prepolymer and water, the emulsifying and dispersing temperature is preferably low, 5 to 40 ° C, and more preferably 5 to 30 ° C. It is preferably carried out in the range of 5 to 20 ° C.

Next, the polyamine compound used in the present invention has at least two primary amino groups in the same molecule.
And a compound having at least one secondary amino group are used, and examples thereof include diethylenetriamine, triethylenetetramine, and dipropylenetriamine.
These polyamine compounds are used in such an amount that the ratio of (the number of terminal isocyanate groups of the urethane prepolymer) / (the number of primary amino groups of the polyamine) is 1/1 to 1 / 0.7. Can be decided If this ratio is less than 1/1 (large molar ratio of primary amino groups), effective high molecular weight tends to be hindered, and larger than 1 / 0.7 (small molar ratio of primary amino groups). , The amount of active amino groups introduced is reduced, the amount of polymerizable unsaturated groups introduced in the next step is necessarily reduced, and the effect of exhibiting physical properties of the emulsion composition of the present invention is reduced, and the emulsion is It is not preferable because the composition thickens and gels.

After the above urethane prepolymer is emulsified and dispersed in water, the above polyamine compound is added and the terminal isocyanate groups of the urethane prepolymer and polyamine are reacted in an emulsified and dispersed system. In carrying out this reaction, an emulsifying and dispersing device such as a homomixer or a homogenizer is used to carry out a uniform reaction. Further, in consideration of gelation caused by rapid reaction, emulsion destruction due to local reaction, etc., product stability afterwards, and stability over time, 5 to 40 ° C, preferably 5 to 30 ° C, more preferably 5 The reaction is carried out in the temperature range of -20 ° C, and the polyamine chain extension reaction is usually carried out for 10 to 120 minutes.

According to this method, the primary amino group in the polyamine compound molecule having a faster reaction rate with respect to the isocyanate group selectively participates in the chain extension reaction. As a result, the site of the secondary amino group in the polyamine compound molecule is introduced into the polyurethane skeleton structure. In this way, the active amino group-containing polyurethane emulsion used in the present invention is produced. When an organic solvent is contained in the emulsified dispersion, the pressure may be reduced to 30 to 70 if necessary.
The active amino group-containing polyurethane emulsion used in the present invention can be obtained by distilling off the organic solvent at ℃.

At this time, phosphoric acid, hydrochloric acid, benzoyl chloride or the like can be added to suppress the side reaction between water and the isocyanate group and accelerate the reaction between the isocyanate group and the polyamine compound.

Next, the polymerizable unsaturated isocyanate-containing isocyanate used in the preparation of the coating composition of the present invention will be exemplified.
General organic polyisocyanates such as hexamethylene diisocyanate, xylylene diisocyanate, cyclohexylmethane diisocyanate, isophorone diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate or dimers or trimers thereof, and acryloyl such as hydroxyl methacrylate or hydroxyl acrylate. Examples thereof include a group-containing hydroxyl group compound and / or an alkylene oxide adduct thereof, or an addition reaction product of allyl alcohol and / or an alkylene oxide adduct of allyl alcohol. Other examples include 2-methacryloyloxyethyl isocyanate represented by the structural formula 1 and m-isopropenyl- represented by the structural formula 2.
Examples include α, α-dimethylbenzyl isocyanate and methacryloyl isocyanate represented by the structural formula of Chemical formula 3.

[0035]

[Chemical 1]

[0036]

[Chemical 2]

[0037]

[Chemical 3]

These polymerizable unsaturated group-containing isocyanate compounds are added to the active amino group-containing polyurethane emulsion obtained in the above step, and more preferably, they are added dropwise and mixed to carry out the reaction.

The addition reaction of the polymerizable unsaturated group-containing isocyanate compound to the active amino group-containing polyurethane emulsion is carried out at a temperature of 5 to 40 ° C., more preferably 5 to 30 ° C. for 15 minutes to 120 minutes. Will be implemented. If the reaction temperature is lower than 5 ° C, the reaction between the active amino group and the polymerizable unsaturated group-containing isocyanate compound is delayed, and a side reaction between the polymerizable unsaturated group-containing isocyanate compound and water occurs, which is not preferable. On the other hand, when the reaction temperature is higher than 40 ° C., a side reaction between the polymerizable unsaturated group-containing isocyanate compound and water is induced, so that the reaction rate between the active amino group and the polymerizable unsaturated group-containing isocyanate compound decreases. . Therefore, the amount of the polymerizable unsaturated group introduced into the urethane skeleton is necessarily reduced.

The amount of the polymerizable unsaturated group-containing isocyanate compound added is (the number of moles of the active amino group of the active amino group-containing polyurethane emulsion) / (the number of moles of the isocyanate group of the polymerizable unsaturated group-containing isocyanate compound). Is added such that the ratio of is 1.05 to 1 / 0.8. When this ratio is smaller than 1 / 1.05 (the molar ratio of isocyanate groups is large), the polymerizable unsaturated group-containing urea body in the free state due to the reaction between the polymerizable unsaturated group-containing isocyanate compound and water, It is not preferable because the amount of the saturated group-containing amine compound increases. Also,
If this ratio is larger than 1 / 0.8 (the molar ratio of isocyanate groups is small), the amount of the polymerizable unsaturated groups introduced will inevitably decrease, and the effect of exhibiting physical properties of the emulsion composition of the present invention will decrease. It is not preferable. Furthermore, if a large amount of active amino groups remain, burning and yellowing of the film after curing are increased, which is not preferable.

By the above reaction, the radiation curable polyurethane aqueous dispersion used in the coating composition of the present invention is obtained.

Next, the photosensitizer which is one of the components of the coating composition of the present invention will be described. As the photosensitizer, acetophenone type, benzoin ether type, ketal type,
Examples thereof include benzophenone-based and anthraquinone-based derivatives. Examples thereof include 2-hydroxy-2-methyl-1-phenylpropan-1-one, alkyl benzoin ether such as isopropenyl benzoin ether, methyl orthobenzoyl benzoate, benzyl methyl ketal, ethyl anthraquinone and the like. These are single or 2
You may use together 1 or more types.

The amount of addition is 0.3 to 10%, preferably 0.3 to 5% based on the solid content of the radiation-curable polyurethane water dispersion in order to achieve photocrosslinking. . Further, these are added by a method such as adding them as they are, or emulsifying them in water with an emulsifier and then adding them to the radiation-curable polyurethane aqueous dispersion.

As described above, the radiation-curable coating composition of the present invention containing the radiation-curable aqueous polyurethane dispersion and the photosensitizer as essential components can be obtained.

[0045]

The radiation-curable coating composition of the present invention is a water-based polyurethane emulsion. Since the polyurethane skeleton contained in this emulsion has a polymerizable unsaturated group, a dense network structure is formed by irradiation with radiation. Can be formed. By forming this network structure, the coating film after curing does not become brittle, and the adhesion to the adherend material becomes good.

The radiation-curable coating composition of the present invention is characterized by the preparation of an active amino group-containing polyurethane emulsion and a radiation-curable polyurethane aqueous dispersion prepared by the reaction of this emulsion with a polymerizable unsaturated group-containing isocyanate compound. The photosensitizer is used as an essential component.

As a result, energy saving and UV light curing for short-time processing are possible. Therefore, the conventional heat-reactive emulsion having a blocked isocyanate group requires high-temperature treatment, which solves the problem that the heat resistance of the adherend material becomes a problem and the applicable range is limited.

Further, by UV light curing, the cured film forms a structure having a high crosslink density. Therefore, it is possible to solve the drawbacks of the conventional polyurethane emulsion having no reactive group, such as the lack of performances such as heat resistance, solvent resistance and chemical resistance of the coating film.

On the other hand, since it is aqueous, the viscosity can be adjusted by adding water to adjust the coating film thickness and the like. Therefore, it is possible to solve problems such as residual monomer specific odor after curing due to the use of a large amount of diluting monomer used for diluting a conventional radiation curable resin, and insufficient adhesion to an adherend due to resin curing shrinkage. .

When it is necessary to increase the hardness of the cured film, the radiation-curable coating composition of the present invention can be used in combination with a water-soluble reactive diluent monomer. As the water-soluble reactive diluent monomer, for example, dimethylacrylamide, vinylpyrrolidone, ethylene glycol,
Examples thereof include diacrylate of diethylene glycol and diacrylate of low molecular weight polyethylene glycol.

Further, the radiation-curable coating composition obtained in the present invention can be used in combination with other water-based resin emulsion. For example, it can be used as a modifier in combination with a general polyurethane emulsion, vinyl acetate, ethylene vinyl acetate copolymer, acrylic ester resin emulsion and synthetic rubber latex such as natural rubber, SBR and NBR.

Further, it is also useful to use a system in which the radiation-curable coating composition of the present invention is used in combination with the water-soluble reactive diluent monomer as a modifier in addition to the other water-based resin emulsion.

[0053]

The radiation-curable coating composition according to the present invention has the following unique effects.

Since the radiation-curable coating composition of the present invention contains a polyurethane aqueous dispersion having a polymerizable unsaturated group in the polyurethane skeleton and a photosensitizer, it can be UV-crosslinked. Therefore, it is possible to save energy and improve workability and physical properties of the coating film by processing in a short time, which cannot be obtained by the conventional polyurethane emulsion.

Since it is an aqueous emulsion, the viscosity of the paint can be adjusted by adding water. Therefore, it is possible to solve the problem of safety due to residual monomers in the conventional cured coating film of radiation curable resin and the problem of insufficient adhesion to the adherend material.

The coating composition of the present invention can be used in a wide variety of applications, for example, metal and plastic primers used in the fields of automobiles, home appliances and the like, woodworking primers, wall materials such as cement boards (inorganic materials). ) For use as a primer or the like. Further, the coating composition of the present invention can be used not only as a primer,
It can also be used as an intermediate coat for these adherends. Further, it can be used as a film primer, a vibration damping paint, and the like.

When the coating composition of the present invention is used for these applications, a coating film having a high crosslink density is formed when the coating composition of the present invention is applied to, for example, a metal surface. However, the anticorrosion effect becomes very large. Moreover, since the adhesiveness is excellent and the strength, hot water resistance, solvent resistance and the like are also excellent, the film thickness of the coating film can be reduced.

[0058]

EXAMPLES The present invention will be described below with reference to the agents, but the present invention is not limited to these examples. still,
"Parts" and "%" in Examples, Synthesis Examples, Comparative Examples and Comparative Synthesis Examples, which will be described later, represent parts by weight and% by weight, respectively, unless otherwise specified.

<Example> 350 parts of polyester polyol (butylene adipate, molecular weight 2000), 10.1 parts of trimethylolpropane, 3 parts of polyethylene glycol
5 parts (molecular weight 600), PO (propylene oxide)
/ EO (ethylene oxide) random copolymer polyether polyol 35 parts, (PO / EO = 30/70, molecular weight 3400), and 1,4-butanediol 78.3.
Parts to 400 parts of methyl ethyl ketone and dissolved,
310 parts of isophorone diisocyanate are used to bring the system temperature to 50 ° C.
Added in. Then, dibutyl tin dilaurate 0.0
5 parts are added, and the system temperature is gradually raised to 75 ° C.
When the reaction was carried out at 75 ° C. for 60 minutes, 0.05 part of dibutyltin dilaurate was added. After that, the reaction was continued and cooled at the time of 75 ° C./200 minutes, and the system temperature was adjusted to 50 ° C. The free isocyanate group of the urethane prepolymer after cooling to 50 ° C. was 2.0% (relative to solid content).

Next, at an internal temperature of 45 ° C., 80 parts of a polyoxyethylene allylphenol ether type nonionic surfactant (HLB = 15), which is an ethylene oxide adduct of distyrenated phenol, was added and mixed for 10 minutes. . After that, the contents in the system are heated to 300 using a homomixer.
The mixture was stirred at 0 rpm at high speed, 1300 parts of distilled water was gradually added thereto, and then emulsification was carried out at a system temperature of 30 ° C. for 20 minutes.

After further cooling the system temperature to 20 ° C., an aqueous solution of diethylenetriamine in which 18 parts of diethylenetriamine was dissolved in 130 parts of distilled water (molar ratio of urethane prepolymer terminal NCO group / primary amino group in diethylenetriamine = 1/0. 9) was added. System temperature 20 to 2
The temperature was controlled to 5 ° C. and stirring was continued for 60 minutes using a homomixer at 3000 rpm. Next, methyl ethyl ketone used as a solvent was recovered under reduced pressure (water bath 40 ° C.) by an evaporator. As described above, the active amino group-containing polyurethane emulsion used in the present invention could be prepared.

The obtained active amino group-containing polyurethane emulsion was analyzed. The results are shown in Table 1. Amount of active amino groups contained (amine value, hereinafter “Am · V”)
10 parts of the emulsion was stirred and dissolved in 300 parts of N-methyl-2-pyrrosodone, and titrated with hydrochloric acid using bromphenol blue as an indicator.

[0063]

[Table 1]

Next, 1000 parts of the active amino group-containing polyurethane emulsion obtained above is kept at a system temperature of 25 ° C. and stirred at 1000 rpm with a homomixer. Hydroquinone monomethyl ether 0.2
After adding a solution of 2 parts of isoproalcohol dissolved in 2 parts of 2-methacryloyloxyethyl isocyanate 1
0.2 part was gradually added dropwise over 10 minutes. afterwards,
Stirring was continued at 25 ° C., and stirring was continued until the measured value of Am · ■ became constant.

As a result, stirring for 60 minutes is required, and Am.V
The value was 0.25 (for all systems), and it is clear that the active amino groups in the active amino group-containing polyurethane emulsion and the isocyanate groups of 2-methacryloyloxyethyl isocyanate have reacted. As a result, a white liquid emulsion having a solid content of 40.2% was obtained.

A radiation curable coating material of Example was prepared by adding the photosensitizer shown in Chemical formula 4 to this polyurethane emulsion. The photosensitizer is added as an aqueous solution, and the composition of the aqueous solution is such that the photosensitizer and the polyoxyethylene allylphenol ether type nonionic surfactant (HLB = 15)
And water, and the ratio is 10 parts / 8 parts / 82 parts.

Reference Example In the radiation curable coating material of the above-mentioned example, the radiation curable coating material of the reference example was prepared without adding the photosensitizer.

[0068]

[Chemical 4]

Comparative Example A urethane prepolymer having a free isocyanate group of 2.0% was prepared in the same manner as in the example. After that, emulsification was carried out in the same manner as in Example, and then ethylenediamine was added in the same molar amount instead of diethylenetriamine and stirred. Next, the solvent used, methyl ethyl ketone, was recovered by an evaporator. From the above, a polyurethane emulsion according to the prior art was obtained. The analysis results of this polyurethane emulsion are also shown in Table 1. As can be seen from the amino group content in Table 1, this polyurethane emulsion has almost no active amino groups. The conventional polyurethane emulsion thus obtained was used as a coating material of a comparative example.

<< Evaluation of Physical Properties of Coating Film >> The physical properties of the coating films of Examples, Reference Examples and Comparative Examples and the physical properties of the coating films when applied to various materials were evaluated to investigate the performance as a coating material.

<Physical properties of film> The radiation-curable coating compositions of Examples and Reference Examples were applied on a Teflon plate, dried overnight at room temperature, and further dried at 60 ° C. for 2 hours, and then subjected to a high pressure mercury lamp (irradiation intensity 80 W. / Cm ² , the focal point distance 8 cm),
A coating film was prepared by performing photopolymerization by ultraviolet irradiation. Each coating thickness is 200 microns. In Experimental Example 1 and Example 3, the paints of Examples and Comparative Examples were applied and then cured at 5 m / min, and in Experimental Example 2, the paint of Example was applied and then cured at 20 m / min. The results of measuring the physical properties of the prepared coating film are shown in Table 2.

The coating composition of Comparative Example was similarly applied onto a Teflon plate, dried overnight at room temperature, and further dried at 60 ° C. for 2 hours to prepare a film. The results of measuring the physical properties of this coating are shown in Table 2 as Comparative Experimental Example 2.

[0073]

[Table 2]

Among the physical properties shown in Table 2, strength, elongation, 1
00% modulus (100% MO) and 200% modulus (200% MO) are tensile tester (Autograph manufactured by Shimadzu Corporation) according to JIS-K-6301.
Was measured at a pulling speed of 100 mm / min.

Solvent resistance is ethyl acetate / toluene = 1 /
Immerse a 2 x 4 cm piece of film in the solvent of 1 and leave at 24
It was measured by the swelling ratio (%) of the film area after time immersion.
The swelling ratio is calculated by the following formula.

Film swelling rate = 100 × (area after swelling-initial area) / (initial area) Water resistance was measured by immersing a 2 × 4 cm film piece in warm water at 70 ° C. and immersing at 70 ° C. for 24 hours. The swelling ratio of the coating area was measured. The swelling ratio is obtained by the above formula.

<Physical Properties of Coating Films Applied to Metals> The radiation-curable coating compositions of Examples and Reference Examples were applied to cold-rolled steel sheets so as to have a film thickness of 10 μm, and dried by force at 80 ° C. As in the section "Physical properties of coating film", a test piece was obtained by photopolymerization by irradiating ultraviolet rays with a high-pressure mercury lamp at different light curing speeds. Adhesion and the like of these test pieces were evaluated, and the results are shown as Experimental Examples 4, 5 and 6 in Table 3.
Shown in.

Similarly, the coating material of the comparative example was applied to a cold rolled steel sheet so as to have a film thickness of 10 μm, forcedly dried at 80 ° C., and the adhesion and the like were evaluated. The results are shown in Comparative Experimental Example 2
Is shown in Table 3.

[0079]

[Table 3]

Each test method is as follows.

[Close contact with goggles] The surface of the test piece coated with the coating material was scratched in the direction orthogonal to each other at equal intervals (1 mm) to form a grid of 10 × 10 = 100 rectangles. Was formed. Cellophane tape is pressure-bonded to the board and then peeled off with a strong force, and the number of rectangles in which no coating film adheres to the cellophane tape and is not peeled from the test piece is counted. The larger the number, the greater the adhesion.

[Warm water resistance] The test piece was immersed in warm water at 40 ° C for 48 hours.
After soaking for a time, the appearance was changed.

[Chemical resistance] Ethyl acetate was soaked in gauze, and a rubbing test was conducted by rubbing the surface of the test piece with this gauze, and changes in the appearance of the coating film were observed. The evaluation results are shown below.

◎ Very good ○ Good △ Somewhat bad × Poor [Impact resistance test] Dupont type impact resistance test (JIS-K
5400, punch diameter ¼ inch, weight of 500 g, height 50 cm), and the appearance of the coating film was observed.

[Salt Water Spray Test] Salt water was sprayed on the test piece for 120 hours, and changes in appearance were observed.

<Physical properties of coating film applied to wood> The radiation-curable coating compositions of Examples and Reference Examples were applied to Lauan material by brushing three times, left at room temperature for 24 hours, and then dried at 40 ° C for 30 minutes. After that, using a high-pressure mercury lamp similar to the one described in "Physical properties of film", the light irradiation time was changed, and photopolymerization by ultraviolet irradiation was performed to obtain a test piece. The adhesion and the like of these test pieces were evaluated, and the results are shown in Table 4 as Experimental Examples 7, 8 and 9.

Similarly, the paint of Comparative Example was applied to the Lauan material by brushing three times, left at room temperature for 24 hours, and then dried at 40 ° C. for 30 minutes to evaluate the adhesion and the like. The results are shown in Table 4 as Comparative Experimental Example 3.

[0088]

[Table 4]

Each test method is as follows.

[Adhesion of goggles] The distance between orthogonal scratches is 2 mm.
The same as the method described in the section "Physical properties of coating film applied to metal" except that the above-mentioned conditions and 5 * 5 = 25 cross-cuts were formed.

[Water resistance] The test piece was immersed in tap water for one week, and the change in appearance was observed. The evaluation results are shown below.

◎ Very good ○ Partial whitening △ Whitening × peeling <Physical properties of the UV-curable coating as a primer> The radiation-curable coating composition of the example containing a photosensitizer was applied to the lauan material by brushing three times. And leave it at room temperature for 24 hours, then 40 ℃
And dried for 30 minutes. After that, 100 parts of UV curable resin [New Frontier R-1300 (manufactured by Daiichi Kogyo Seiyaku,
Ester urethane acrylate) / New Frontier TMP-3 (Daiichi Kogyo Seiyaku Co., Ltd., trimethylolpropane triacrylate) / N-vinylpyrrolidone = 45 /
30/25] and 3 parts of the photosensitizer of the above-mentioned Chemical formula 4 was applied by a roll coater in an amount of 10 g / m ² , and the coated plate was irradiated with the same high pressure mercury lamp as above for 2 seconds. Got The adhesion and the like of this coated plate were evaluated, and the results are shown in Table 5 as Experimental Example 10.

Similarly, the paint of Comparative Example was applied to the Lauan material,
Dried. Then, the above-mentioned UV-curable coating material was applied in the same amount as 10 g / m ² , and the same UV irradiation was performed as described above to obtain a coated plate. The adhesion and the like of this coated plate were evaluated, and the results are shown in Table 5 as Comparative Experimental Example 4.

[0094]

[Table 5]

Each test method is as follows.

[Cohesion of goggles] The surface of the test piece coated with the coating material was scratched in the direction orthogonal to each other at equal intervals (1 mm) to form a grid of 10 × 10 = 100 rectangles. Was formed. Cellophane tape is pressure-bonded to the board and then peeled off with a strong force to count the number of rectangles which are not peeled off from the test piece because the radiation-curable paint layer and the ultraviolet-curable paint layer thereabove are not peeled off. The larger the number, the greater the adhesion.

<Physical properties of coating film applied on film> A radiation-curable coating composition of Example containing a photosensitizer was used as a commercially available polyethylene terephthalate film (thickness 70 mm).
To the thickness of 5 microns and dried at room temperature for 2 hours, then 8
It was forced to dry at 0 ° C. Next, an ultraviolet curable ink (UVS-PCD-Red T, manufactured by Morohoshi Ink Co., Ltd.) was printed to a thickness of 4 microns, and the speed was 5 m / min with the same high pressure mercury lamp as above.
Cured.

Similarly, the paint of Comparative Example was applied as a primer agent to the same polyethylene terephthalate film as above and dried in the same manner. Next, the same UV-curable ink as described above was printed to a thickness of 4 μm, and UV-cured as described above. The adhesion of the ultraviolet curable ink on the top coat surface of these test pieces was evaluated. The results are shown in Table 6 as Experimental Example 11 and Comparative Experimental Example 5.

Further, a test piece was prepared by coating and curing the above-mentioned polyethylene terephthalate film with an ultraviolet curable ink without using the primer agent of the radiation curable coating composition. The adhesion of this test piece was also evaluated. The results are shown in Table 6 as Comparative Experimental Example 6.

[0100]

[Table 6]

Each test method is as follows.

[UV Ink Adhesiveness] A cellophane tape (manufactured by Niban) is adhered to the film surface so that air bubbles do not enter,
The weighted roller was used to make a close contact. Next, hold both ends of the test piece that are not adhered to the tape with both hands,
It was peeled off with a strong force and the peeled state of the ultraviolet curable ink was observed. The evaluation criteria are as follows.

○ All of the UV ink remained on the polyester film △ About half of the UV ink remained on the polyester film × All the UV ink transferred to the tape As a result, the radiation curable coating composition of the present invention was used. The coating prepared by any of the above materials clearly has adhesion, water resistance and chemical resistance as compared with the coating composition of the prior art due to the addition of the photosensitizer and photopolymerization when applied to any material. Improvements are seen in terms of properties and appearance.

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[Procedure amendment]

[Submission date] November 18, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0042

[Correction method] Change

[Correction content]

Next, the photosensitizer which is one of the components of the coating composition of the present invention will be described. As the photosensitizer, acetophenone type, benzoin ether type, ketal type,
Examples thereof include benzophenone-based and anthraquinone-based derivatives. For example, 2-hydroxy-2-methyl-1-phenylpropan-1-one, isopropylbenzoine
Examples thereof include alkyl benzoin ethers such as ether, methyl orthobenzoyl benzoate, benzyl methyl ketal, ethyl anthraquinone and the like. These may be used alone or in combination of two or more.

Claims (3)

[Claims] 1. A radiation-curable polyurethane water dispersion obtained by adding a polymerizable unsaturated group-containing isocyanate compound to an active amino group-containing polyurethane emulsion in the presence of water and reacting it, and a photosensitizer. A radiation-curable coating composition comprising: 2. The active amino group-containing polyurethane emulsion is obtained by emulsifying and dispersing in water a urethane prepolymer having an isocyanate group at the molecular end, which is obtained by reacting a compound containing two or more active hydrogens with an organic polyisocyanate. And then obtained by adding and reacting a polyamine having at least two primary amino groups and at least one secondary amino group in the same molecule in the presence of water. The radiation-curable coating composition described. 3. The addition of the polyamine to the urethane prepolymer comprises:
The radiation-curable coating composition according to claim 2, wherein the molar ratio of (CO group) / (primary amino group of the polyamine) is in the range of 1/1 to 1 / 0.7. object.