JPH0780989B2 - Method for producing ultraviolet or radiation curable resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Object of the invention Industrial field of application The present invention is an ultraviolet or radiation curable type useful for paints, inks, conductive paints and the like that use radiation such as ultraviolet rays or electron beams as a curing means. The present invention relates to a method for producing a resin composition, wherein the composition according to the present invention has excellent properties of cured film coating such as mechanical properties and transparency, and also has excellent properties of adhesion to metals and metal oxides and dispersibility. It is a thing.

2. Description of the Related Art Urethane (meth) acrylates have various chemical structures depending on the combination of raw materials for producing them, that is, various alcohols, isocyanate compounds and hydroxyl group-containing (meth) acrylates, some of which are already commercially available. It is used for various purposes. On the other hand, the technology of curing the resin by radiation such as ultraviolet rays and electron beams, from the viewpoint of improving line speed, resource saving, environmental measures, etc.
It is continuing to develop as a technology that replaces conventional thermosetting. With respect to paints, inks, conductive paints, etc., development of production technology using radiation curing has been widely carried out, but it is hard to say that it has reached a satisfactory level. A major cause of this is that the urethane (meth) acrylates used for these have not yet achieved excellent cured coating properties and good adhesion and dispersibility to metals and metal oxides. Has been.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention As described above, various urethane (meth) acrylates have been used in the past, but they have excellent cured film properties and excellent adhesion and dispersibility to metals and metal oxides ( (Meth) acrylate is not yet known. From such a situation, the present invention provides a urethane (meth) having excellent mechanical properties, transparency, adhesion to a metal substrate, and excellent adhesion and dispersibility to metals and metal oxides. ) It is intended to provide a method for producing an ultraviolet ray or radiation curable resin composition containing acrylate as a curable component.

(B) Structure of the invention Means for solving the problems As a constant problem in the fields of paints, inks, conductive paints, etc., the mechanical properties, surface gloss, transparency, and base of the binder resin used for these are It has cured film properties such as adhesion to materials. For ultraviolet or radiation curable resins, urethane (meth) acrylate is often used for these applications because of the toughness of the cured coating film. However,
Urethane (meth) acrylate has the drawback of not having sufficient adhesion to metal substrates, as well as adhesion to pigments such as metals and metal oxides required for binder resins for paints, inks and conductive paints. And dispersibility are not sufficient. In order to improve dispersibility in metals and metal oxides, improvement in terms of molecular weight and molecular structure and addition of a dispersant having a polar group are often carried out, but the former method requires the binder resin. However, the latter means is not preferable because there is a change with time due to migration of the dispersant after curing to the surface.

As a result of intensive studies by the present inventors, an ultraviolet or radiation resin composition made of a urethane (meth) acrylate having a carboxyl group in the molecule produced by a specific production method has excellent mechanical properties and transparency. It has been found that it has a cured coating film characteristic such as surface gloss and adhesion to a metal substrate, and excellent adhesion and dispersibility to metals and metal oxides.

Regarding the urethane (meth) acrylate having a carboxyl group in the molecule, JP-A-61-18610 discloses that
It was prepared by reacting polyhydric alcohol containing 2,2- (dihydroxymethyl) propionic acid and polyisocyanate all at once to produce a terminal isocyanate urethane oligomer, and reacting this with hydroxyl group-containing (meth) acrylate. Things are known. This production method or 2,2- (dihydroxymethyl) in this production method
According to the production method using other acid diol as a raw material instead of propionic acid, a compound (I) having an average structure shown below is produced.

R- (M-X) _l- M-R (I) where R: a residue of a hydroxyl group-containing (meth) acrylate, M: a residue of a polyvalent isocyanate, X: 2,2- (dihydroxylmethyl) propionic acid or Residue l of other acid diols: A positive number is shown, and R, M and X are linked by a urethane bond.

This compound (I) has poor compatibility with various other ultraviolet or radiation curable monomers and oligomers, and a coating film obtained by curing an ultraviolet or radiation resin composition containing this compound (I) is Since the compound (I) causes phase separation, there are problems such as reduction in toughness of the coating film, white turbidity, reduction in surface gloss, and reduction in adhesion to a metal substrate.

Under such circumstances, the present inventors have investigated compound (I)
UV- or radiation-curable resin composition containing a carboxyl group-containing urethane (meth) acrylate whose content of carboxylic acid has been reduced as much as possible has excellent mechanical properties, transparency, surface gloss, and adhesion to metal substrates. The present invention has been completed as a result of finding that a cured coating film is formed, and that the adhesion and dispersibility to metals and metal oxides are extremely excellent, and further examining the manufacturing method thereof.

Next, a method for producing the carboxyl group-containing urethane (meth) acrylate-containing composition of the present invention will be described.

Raw Materials Hydroxyl group-containing (meth) acrylate Examples of the hydroxyl group-containing (meth) acrylate that can be used in the present invention include the following. 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, ε-caprolactone adduct of 2-hydroxylethyl (meth) acrylate, trimethylolpropane di (meth) acrylate,
Pentaerythritol tri (meth) acrylate and the like.

Polyvalent isocyanates which can be used in the present invention include, for example, diisocyanates such as tolylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, diphenylmethane-4,4-diisocyanate, isophorone diisocyanate and methyllysine diisocyanate, and 2 Mention may be made of triisocyanates such as 4,4,6-toluenthisocyanate. Of these, more preferred are diisocyanates.

Polyhydric alcohol The polyhydric alcohol used in the present invention may be divalent or higher, but dihydric alcohol is more preferable. The alcohol referred to here is a compound having a hydroxyl group in the molecule other than the acid diol, and for example, a) saturated polyester polyol b) unsaturated polyester polyol.
C) Polyether polyol d) Polycaprolactone polyol f) Fatty acid ester and the like can be mentioned. Specific examples thereof are as follows.

B) Saturated polyester polyols Polyhydric alcohols such as ethylene glycol, propylene glycol, neopentyl glycol, 1,2-butylene glycol, 1.3-butylene glycol, 1,4-butylene glycol, 1,6-hexanediol and trimethylolpropane And a saturated polyester polyol having a hydroxyl group, which can be obtained by an esterification reaction with a saturated polybasic acid such as phthalic acid, isophthalic acid, succinic acid, adipic acid, and sebacic acid.

(B) Unsaturated Polyester Polyol An unsaturated polyester polyol having a hydroxyl group, which is obtained by substituting a part of polybasic acid with a polybasic acid having an unsaturated bond such as maleic acid in the saturated polyester polyol described in (a) above.

C) Polyether polyol Polyethylene glycol, polypropylene glycol,
Propylene oxide adduct of polytetramethylene glycol and glycerin (trade name: Nissan Uniol TG-100
0), polyether polyols such as ethylene oxide adduct of bisphenol A (trade name: Nissan Uniol DA-400).

D) Polycaprolactone polyol A ring-opening polymer of ε-caprolactone, and examples of commercially available products include Placcel L-205AL and Placcel L-212AL (manufactured by Daicel Chemical Industries, Ltd.).

E) Fatty acid ester A fatty acid ester containing a hydroxyl group synthesized from a fat or oil fatty acid or a synthetic fatty acid and a polyhydric alcohol. As the fatty acid used as a raw material, soybean oil, peanut oil, cottonseed oil, safflower oil, olive oil, castor oil Castor oil is particularly preferably used. Other polyhydric alcohols are ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol,
For example, trimethylol propane.

In addition to the polyhydric alcohols shown in the above a) to e), polybutadiene having a terminal hydroxyl group can be used. Further, it is safe to use two or more kinds of these alcohols at the same time.

Acid diol The acid diol used in the present invention is a dihydric alcohol having at least one carboxyl group in the molecule, for example, 2,2-di (hydroxymethyl) propionic acid, 2 having one carboxyl group. 2,2-di (hydroxymethyl) butyric acid and tartaric acid having two carboxyl groups can be used.

Production method A resin composition containing a carboxyl group-containing urethane (meth) acrylate forms a cured coating film having excellent mechanical properties, transparency, surface gloss, and adhesion to a metal substrate, and a metal or metal oxide. In order to exhibit sufficient adhesion and dispersibility with respect to, it is important to minimize the by-product of the compound (I) during the production thereof. As a method for producing a carboxyl group-containing urethane acrylate for that purpose, the following method is extremely excellent.

<1> First, a terminal isocyanate urethane oligomer (A) is produced from a polyhydric alcohol and a polyvalent isocyanate. At this time, the polyvalent isocyanate and the polyhydric alcohol must be prepared so that the degree of condensation in the oligomer (A) is 1 or more. If the condensation degree is less than 1,
A polyisocyanate that does not react with the polyhydric alcohol is produced, and the polyisocyanate reacts with the acid diol to be added later, which causes an increase in the production amount of the compound (I).

<2> Next, the terminal isocyanate urethane oligomer (A) produced in the previous step is reacted with an acid diol to produce a carboxyl group-containing terminal isocyanate urethane oligomer (B). The amount of acid diol at this time is NCO group /
The ratio must be such that OH groups> 1 (molar ratio). In general, acid diols are solids having a high melting point and their solubility in general organic solvents is small, so that the reaction is difficult to proceed. Therefore, it is desirable to properly select the reaction temperature, which is 70 ° C to 120 ° C.
It is preferable to react at ℃, more preferably 80 ℃ ~ 11
It is better to react at 0 ° C. If the reaction temperature is lower than 70 ° C, it is difficult to complete the reaction of the diol acid,
On the contrary, if the temperature is higher than 120 ° C, gelation is likely to occur due to side reaction.

<3> Next, hydroxyl group-containing (meth) acrylate is added to the carboxyl group-containing isocyanate end urethane urethane oligomer (B) produced in the previous step, and OH group / NCO group ≧ 1 (molar ratio)
To produce a carboxyl group-containing urethane (meth) acrylate. At this time, it is preferable to add phenols such as hydroquinone and hydroquinone monomethyl ether, quinones such as benzoquinone, and polymerization inhibitors such as phenothiazine and copper salts.

It should be noted that it is all right to use a catalyst for the urethanization reaction or a reaction solvent in all the above steps. Examples of the urethane-forming reaction catalyst include triethylamine,
N-methylmorpholine, N, N, N ', N'-tetramethyl-
Use tertiary amines such as 1,3-butanediamine, organotin compounds such as tin octenoate and dibutyltin dilaurate, or metal salts of organic acids such as Ti, Na, K, V, Fe, Mn and Pb. You can On the other hand, the reaction solvent is preferably a ketone solvent such as methyl ethone ketone, methyl isobutyl ketone or cyclohexanone, an ester solvent such as ethyl acetate or butyl acetate, an aromatic hydrocarbon solvent such as benzene, toluene or xylene, and other solvents. .

Amount of catalyst or solvent used in each step above, step <1>
The reaction conditions such as the reaction temperature in step <3> or the amount of the polymerization inhibitor used in step <3> may be in accordance with a conventional method.

Average Structure of Product The average structure of the carboxyl group-containing urethane (meth) acrylate produced according to the present invention can be represented by the following formula when a divalent alcohol and a divalent isocyanate are used.

_{R (M-N m M-} Y n M-N m M-R , however, in the above formula R: residue of the hydroxyl group-containing (meth) acrylate M: residues of polyvalent isocyanate N: polyhydric alcohol residue Y: residue of acid diol m: number of 1 or more n: positive number, and R, M, N and Y are bonded by a urethane bond.

In the above structural formula, m and n can be controlled by the reaction molar ratio of the raw material compounds, and a preferable value is m is 1 or more and 10 or less, n is a positive number of 10 or less, and more preferably 0.1 or less.
That is all. When m is less than 1, the content of the compound [I] increases, and when m is 0, the product is the compound [I] itself, which causes the problems described above. On the other hand, when m or n is more than 10, the viscosity of the product becomes high, which causes deterioration of workability, and the curability by ultraviolet rays or radiation becomes poor.

Curing of Composition The resin composition produced by the present invention is easily cured by irradiation with ionizing radiation such as ultraviolet rays, X-rays and electron beams.

When the curing means is UV irradiation, a photoinitiator is used as a polymerization initiator. Examples of industrially frequently used photoinitiators include benzoin alkyl ether, benzophenone, N, N′-diethylaminobenzophenone,
2,2-diethoxyacetophenone, 2,2-dimethoxy-2
-Phenylacetophenone, 2-alkylthioxanthone, chlorothioxanthone, 1-phenyl-1,2-propanedioxime, chlorinated acetophenone derivatives and the like can be mentioned. The amount of these photoinitiators used is 0.01 to 20 wt% with respect to the composition, and more preferably 0.1 to 1%.
It is 0 wt%.

When the curing means is radiation such as electron beam or γ-ray, it is not necessary to use a photoinitiator because it can be rapidly cured without using a photoinitiator.

EXAMPLES, COMPARATIVE EXAMPLES AND REFERENCE EXAMPLES Next, the contents of the present invention will be described more specifically with reference to Examples and Comparative Examples. The present invention is not limited to the embodiments.

Example 1 First, tolylene diisocyanate (hereinafter referred to as TDI) was placed in a 5 L four-necked flask equipped with a thermometer, a reflux cooling device, and a stirring device.
Called. ) 348 parts, (parts by weight, the same applies hereinafter) ADEKA POLYETHER P-1000 [Polypropylene glycol: molecular weight
1000, manufactured by Asahi Denka Co., Ltd.] 1000 parts, methyl isobutyl ketone (hereinafter referred to as MIBK) 1020 parts, toluene 510
Part, 1 part of dibutyltin dilaurate was charged, 70-90 ℃
Was reacted for 4 hours to obtain a terminal isocyanate urethane oligomer (A). Then, 67 parts of 2,2-di (hydroxymethyl) propionic acid (hereinafter referred to as DMPA) was added to the terminal isocyanate urethane oligomer (A),
The reaction was carried out at 80-90 ° C. for 4 hours to obtain a carboxyl group-containing terminal isocyanate urethane oligomer (B). Further, the carboxyl group-containing isocyanate isocyanate urethane oligomer (B) was mixed with hydroquinone monomethyl ether.
After adding 0.7 parts, 116 parts of 2-hydroxyethyl acrylate was added dropwise to the reaction solution kept at 70-80 ° C., and after heating for 2 hours, the mixture was aged for 2 hours to give a number average molecular weight of 3500 (converted to polystyrene) and an acid value. 0.33 meq / g (solid content conversion value) of carboxyl group-containing urethane acrylate (1) was obtained.

Example 2 First, in a 5 L four-necked flask equipped with a thermometer, a reflux cooling device, and a stirring device, TDI 348 parts, PTMG-1000 [polytetramethylene glycol: molecular weight 1000, Mitsubishi Kasei Co., Ltd.
Made] 700 parts, URIC H-62 [castor oil-based polyol: molecular weight
420, manufactured by Ito Oil Co., Ltd.] 126 parts, dibutyltin dilaurate 0.75 parts, MIBK 550 parts and toluene 275 parts were charged, 70
The reaction was carried out at -90 ° C for 4 hours to obtain a terminal isocyanate urethane oligomer (A). Next, 67 parts of DMPA was added to this terminal isocyanate urethane oligomer (A),
The reaction was carried out at -90 ° C for 4 hours to obtain a carboxyl group-containing terminal isocyanate urethane oligomer (B). Furthermore, the carboxyl group-containing isocyanate end urethane urethane oligomer (B) was mixed with hydroquinone monomethyl ether.
After adding 5 parts, 116 parts of 2-hydroxyethyl acrylate was added dropwise to the reaction solution kept at 70-80 ° C, and after the addition, the mixture was heat-aged for 2 hours, the number average molecular weight was 2580 (in terms of polystyrene), and the acid value was 0.37meq. / g (solid content conversion value) of carboxyl group-containing urethane acrylate (2) was obtained.

Comparative Example 1 Using the same apparatus as in Example, 696 parts of TDI and 134 parts of DMPA were used.
And 200 parts of polyethylene glycol # 200 were charged in a flask and the reaction was started at 60 ° C. When temperature was difficult to control, the reaction solution temperature rose to 120 ° C. and gelled.

Comparative Example 2 Using the same device as in Example, 348 parts of TDI and 67 of DMPA were used.
Parts, Adeca polyether P-1000 500 parts, dibutyltin dilaurate 0.85 parts, MIBK 1020 parts, toluene 51
The mixture was placed in a 0 part flask and reacted at 70 to 90 ° C. for 7 hours to obtain a terminal isocyanate prepolymer solution. Next, hydroquinone monomethyl ether was added to this prepolymer solution.
0.7 parts and 232 parts of 2-hydroxyethyl acrylate were added and reacted at 60-80 ° C for 5 hours to give a number average molecular weight of 1580.
(Polystyrene conversion), acid value 0.43 meq / g (solid content conversion value) carboxyl group-containing urethane acrylate (3)
Got

Reference example Using a doctor blade with a gap of 200 μm,
The carboxyl group-containing urethane acrylates (1) to (3) obtained in Examples and Comparative Examples and Comparative Examples were applied onto a polyester film substrate, the solvent was dried by hot air, and the solvent was removed. The coating film was cured by irradiating with an electron beam of 10 Mrad under a nitrogen atmosphere at an accelerating voltage of 170 kv using a type electron beam irradiator. The cured coating film was peeled off from the film substrate, and the transparency and mechanical strength of the coating film were measured.

On the other hand, to the carboxyl group-containing urethane acrylates (1) to (3) obtained in Examples and Comparative Examples, a photoinitiator (Darocurure 1173: manufactured by Merck Japan Ltd.) was added in an amount of 5% by weight based on the solid content. To prepare a coating composition, apply it on a metal substrate using a bar coater # 20, dry it with hot air, then cure by UV irradiation and then perform a peel test to obtain a cured coating film. Was examined for adhesion to a metal substrate. For UV irradiation, use UV-4000 manufactured by Ushio Inc. that collects one 80 W / cm ultra-high pressure mercury lamp, and irradiate once from a distance of 10 cm on the conveyor at a conveyor speed of 5 m / min. Went by.

The results are shown in Table 1.

Further, coating compositions having the compositions shown in Table 2 were prepared using the carboxyl group-containing urethane acrylates (1) to (3) obtained in Examples and Comparative Examples, and mixed and dispersed by a ball mill for 1 hour. After mixing and dispersion, gap spacing 200μm
After applying the paint on the polyester base material using Dr. Blade, drying the solvent with hot air and removing it, ESI
The coating film was cured by irradiating an electron beam with an accelerating voltage of 170 kv and 10 Mrad in a nitrogen atmosphere using an electron curtain type electron beam irradiation device manufactured by the same company. The results of measuring the surface gloss of the obtained coating film are shown in Table 3.

Comparative Example 3 Using the same device as in the example, 348 parts TDI, PTMG-1000
1000 parts, MIBK 1020 parts, toluene 510 parts, and dibutyltin dilaurate 1 part were charged into a flask, and 70 to 90
The reaction was carried out at 4 ° C. for 4 hours to obtain a solution of a terminal isocyanate group prepolymer. Next, DMPA was added to this prepolymer solution.
268 parts was added and reacted at 80 to 90 ° C. for 4 hours to obtain a terminal hydroxyl group prepolymer solution. To this solution, 0.7 parts of hydroquinone monomethyl ether, 348 parts of TDI, and 2-
When 232 parts of hydroxyethyl acrylate was added and the reaction was started at 80 ° C., the viscosity increased and gelled.

Comparative Example 4 Dimethylformamide was used in the same apparatus as in Example.
500 parts, DMPA 268 parts, TDI 696 parts, toluene 1000 parts,
And 1 part of dibutyltin dilaurate was charged into a flask and reacted at 70 to 90 ° C. for 4 hours to obtain a prepolymer solution of an isocyanate group at the terminal. Next, to this prepolymer solution, 1000 parts of PTMG-1000, 0.7 part of hydroquinone monomethyl ether, and 232 parts of 2-hydroxyethyl acrylate were added, and the reaction was started at 80 ° C., the viscosity increased, and the gel Turned into

(C) Effect of the Invention As shown in Table 1, the resin composition obtained according to the present invention is excellent in the mechanical properties of the coating film and in the adhesion to the metal substrate, and is a cured film formed by phase separation. It gives a transparent film without the drawbacks of cloudiness and grain formation. Further, as shown in Table 3, metals and metal oxides are well dispersed. The resin composition according to the present invention is particularly prized in the field of using electron beams, ultraviolet rays, etc. as a curing means by utilizing such characteristics, for example, in the fields of paints, inks, conductive paints and the like.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Sadaaki Tsuji 13-26 Suehiro-cho, Yokkaichi-shi, Mie Ito Oil Co., Ltd. In-house Company Examiner Eiwa Hashimoto (56) References JP 54-139700 (JP, A) JP-A-1-134354 (JP, A) JP-A 61-179219 (JP, A) JP-A 62-10131 (JP, A)

Claims (1)

[Claims] 1. A step of producing a urethane oligomer (A) by reacting a polyhydric alcohol and a polyisocyanate at a ratio such that the degree of condensation of the resulting terminal isocyanate urethane oligomer (A) is 1 or more. <2> The terminal isocyanate urethane oligomer (A) and the acid diol are reacted at a molar ratio in which the ratio of the isocyanate group in the urethane oligomer (A) to the hydroxyl group in the acid diol exceeds 1 to give a carboxyl group-containing terminal isocyanate. A step of producing a urethane oligomer (B), and <3> a carboxyl group-containing terminal isocyanate urethane oligomer (B) and a hydroxyl group-containing (meth) acrylate, and a hydroxyl group-containing (meth) group for the isocyanate group in the urethane oligomer (B) The ratio of hydroxyl groups in acrylate is 1 or more That is reacted in a molar ratio, a manufacturing method of an ultraviolet or radiation curable resin composition characterized by comprising a step of preparing a carboxyl group-containing urethane (meth) acrylate.