JPH0426329B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for producing photocurable oligomers.
More specifically, the present invention relates to a method for producing a photocurable oligomer that can be suitably used as a binder for printing ink. The photocurable oligomer obtained by the production method of the present invention can be suitably used as a binder for printing ink, and can also be used as a binder for overprint varnish, a binder for paint, a solder resist, etc. In particular, the binder for printing ink will be explained as a representative example. [Prior art] Conventionally, ultraviolet curable inks are made by adding a reactive diluent such as trimethylolpropane triacrylate and a photosensitizer to an unsaturated epoxy resin ester, which is usually obtained by reacting an epoxy resin and acrylic acid. It is known as a composition that can be obtained by appropriately blending pigments and pigments. Among these, unsaturated epoxy resin esters and unsaturated polyester resins are positioned as multifunctional oligomers in ink binders, and these oligomers have advantages such as gloss, pigment dispersibility, viscosity, printability, and curing speed. It is a particularly important component among the above components because it is closely related to various properties of the ink. Recently,
Even UV-curable inks are required to have the same level of printability as conventional solvent-based inks.
Conventional polyfunctional oligomers such as unsaturated epoxy resins cannot fully satisfy this requirement. Therefore, there is a demand in this field for the development of ultraviolet curable inks having excellent printability. [Problems to be Solved by the Invention] The present invention has been made in order to solve the above-mentioned problems that could not be solved by the prior art. Therefore, the present inventors took into consideration not only printability but also curing speed, hardness/flexibility of the printed film, on-press stability, etc., and developed an excellent photocuring property that can satisfy these various performances. As a result of extensive research in order to develop oligomers, we have finally found a method for producing photocurable oligomers that can solve the above-mentioned problems, and have completed the present invention. [Means for Solving the Problems] The present invention provides (a) a reaction product of (meth)acrylic acid and rosin glycidyl ester (hereinafter referred to as component (a)) and a diisocyanate (hereinafter referred to as component (b)). ) to obtain a compound having an isocyanate group at the end, and then reacting the compound with a reaction product of (meth)acrylic acid and diepoxides (hereinafter referred to as component (c)). A method for producing a photocurable oligomer, and the above (a)
component, hydroxyl group-containing acrylic ester (hereinafter referred to as (d)
Component) and the component (b) are reacted to obtain a compound having an isocyanate group at the terminal, and then the compound is reacted with the component (c). . [Example] In the present invention, a photocurable oligomer can be obtained by reacting component (a), component (b), component (c), and optionally component (d). The component (a) is a reaction product of (meth)acrylic acid and rosin glycidyl ester, and has the general formula []: (wherein, X represents a rosin residue).
The rosins used here are determined by considering the ultraviolet curing speed of the resulting ink and the color tone of the photocurable oligomer, and are usually treated to stabilize conjugated double bonds, such as hydrogenated rosin or disproportionated rosin. rosin is suitable. The component (b) is a diisocyanate,
Any conventionally known material can be used as is. Specific examples of these include isophorone diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, and phenylene diisocyanate. However, in order to obtain a compound having a free isocyanate group at the end by selectively participating in the reaction with one of the isocyanate groups in component (b) during the reaction with component (a), it is necessary to ( It is desirable that the isocyanate groups present in component b) are not equivalent; taking this point into consideration, isophorone diisocyanate and tolylene diisocyanate are preferred among the above. The component (c) is a reaction product of (meth)acrylic acid and diepoxides, and has the general formula []: (In the formula, R ¹ and R ² are each a hydrogen atom or a methyl group, Y is (l is an integer from 1 to 15), -O-(CH ₂ CH ₂ O-) _n (m is an integer from 1 to 10) (n is an integer from 2 to 18), It is a diacrylate represented by Here, the diepoxides have the general formula []: (In the formula, Y is the same as above). Specific examples of the diepoxides include:
Examples include 1,6-hexanediol diglycidyl ether, tripropylene diglycidyl ether, polypropylene diglycidyl ether, higher dibasic acid diglycidyl ether, and bisphenol A type diglycidyl ether. The above component (d) refers to various acrylic acid ester monomers containing a hydroxyl group, and specific examples include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and those with the general formula [] : (In the formula, R ³ represents a propyl group, butyl group, phenyl group, etc., and R ⁴ represents a hydrogen atom or a methyl group.)
Examples include monomers represented by To explain the method for producing the constituent components used in the method for producing the photocurable oligomer of the present invention, component (a) is obtained by subjecting (meth)acrylic acid and rosin glycidyl ester to an esterification reaction. Known catalysts such as imidazoles and quaternary ammonium salts are used as catalysts.
Also, as polymerization inhibitors, phenols, quinones,
Known compounds such as phenothiazine can be appropriately selected and used. The molar ratio of (meth)acrylic acid and rosin glycidyl ester is stoichiometrically 1:1, but industrially it is 1:0.9.
It is sufficient if it is in the range of ~1.1. The amount of the esterification catalyst used is 0.1 to 2 parts per 100 parts (parts by weight, the same applies hereinafter) of the total amount of (meth)acrylic acid and rosin glycidyl ester, and the amount of the polymerization inhibitor used is the total amount of the charged amount. The amount is preferably 0.001 to 0.5 parts per 100 parts. The reaction temperature is usually 80 to 130°C, and the reaction time is determined by monitoring the acid value of the product, and is usually 3 to 10 hours. Component (c) is obtained by subjecting (meth)acrylic acid to an esterification reaction with the diepoxide represented by the general formula [], and during this reaction, the
The same esterification catalyst and polymerization inhibitor as used in the production of component (a) can be used. (meta)
The molar ratio of acrylic acid and diepoxides is stoichiometrically 2:1, but industrially it is 2:1.
It may be within the range of 0.9 to 1.1. A photocurable oligomer can be produced by preparing the various components thus obtained according to the following method. That is, the component (a) above and, if necessary, the component (d) above.
It can be obtained by adding and reacting component (b) in the presence of components to obtain a compound having a free isocyanate group at the terminal, and then reacting the compound with component (c). When component (b) is added and reacted in the presence of component (a) and optionally component (d), the molar ratio of the former and component (b) is stoichiometrically 1:
1, but industrially it may be within the range of 1:0.9 to 1.1. Since this reaction is essentially a reaction between an isocyanate group and a hydroxyl group, if the reactivity of the isocyanate group in component (b) is equivalent, component (a) or (d) is present at both ends of component (b). ) components react,
It is not always easy to selectively leave free isocyanate groups at the end of the molecule, resulting in some by-products. However, if tolylene diisocyanate, isophorone diisocyanate, etc. are used as component (b), the desired intermediate can be easily obtained due to the difference in reactivity of both isocyanate groups. The reaction conditions at this time are determined as appropriate by monitoring the NCO value, and the reaction temperature is usually 60 to 100°C.
The reaction time may be in the range of 1 to 5 hours. Next, the intermediate and component (c) are reacted. In such a case, the same conditions as those for producing the intermediate can be set, and in this case, the molar ratio of the intermediate and component (c) to be charged is as follows.
The ratio may be 2.2 to 0.9:1. The charging molar ratio is approximately 1:
If the molar ratio is about 1, the oligomer will be primarily a trifunctional oligomer, and if the molar ratio is approximately 2:1, the oligomer will be primarily a tetrafunctional oligomer. The present invention will be explained in detail below with reference to Synthesis Examples, Examples, and Comparative Examples, but the present invention is not limited to these examples. Synthesis Example 1 (Rosin epoxy acrylate) After replacing the inside of a 5-volume flask equipped with a stirrer, thermometer, condenser, and nitrogen inlet tube with nitrogen gas, disproportionated rosin monoglycidyl ester
2568 parts (5.81 mol), 98% (weight%, same below)
427 parts (5.81 mol) of acrylic acid, 3.0 parts of benzyltrimethylammonium chloride (hereinafter referred to as BTMAC) as an esterification catalyst (based on the total amount charged)
1000ppm), 3.0 parts of polymerization inhibitor 4-methoxyphenol (hereinafter referred to as MEHQ) and 3.0 parts of phenothiazine, and heated at 105 to 110°C under a nitrogen stream.
The reaction was completed over 6 hours. The acid value of the reaction product was 4.8, and the appearance was brown and transparent balsamic. Synthesis Examples 2 to 6 (Bifunctional acrylic ester compound) In Synthesis Example 1, as shown in Table 1, the type and amount of the epoxy compound, the amount of acrylic acid,
Various bifunctional acrylic ester compounds were obtained in the same manner as in Synthesis Example 1 except that at least one of the amount of BTMAC, phenothiazine, MEHQ and reaction time was changed.

[Table] (Note) In Synthesis Examples 2 to 6, the molar ratio of the epoxy compound to acrylic acid was 1.
In addition, in Table 1, the epoxy compounds refer to those shown in Table 2.

【table】

[Table] Example 1 A 1-volume flask equipped with a stirrer, a thermometer, a condenser, and a nitrogen inlet tube was filled with nitrogen gas, and then 228.6 parts of rosin epoxy acrylate obtained in Synthesis Example 1 and isophorone Diisocyanate (hereinafter referred to as IPDI) 98.9 parts and MEHQ 0.525
After reacting at 75-80℃ for 1 hour,
197.5 parts of the bifunctional acrylic ester compound obtained in Synthesis Example 2 was charged, and the reaction was continued for an additional hour.
Next, two drops of octyl stannous as a urethanization catalyst were added, and the mixture was stirred and reacted at the same temperature for 3 hours to obtain an oligomer. The performance of the clear cured film of the obtained oligomer and its performance as an ultraviolet curable printing ink were evaluated by the following evaluation method, and the results are shown in Tables 4 and 5. Examples 2 to 8 In Example 1, the amount of rosin epoxy acrylate used, the type and amount of diisocyanate, and the type of bifunctional acrylic ester compound (bifunctional acrylic ester compound shown in Synthesis Examples 2 to 6)
Various oligomers were obtained in the same manner as in Example 1 except that at least one of the amounts was changed as shown in Table 3. The performance of these oligomers was evaluated and the results are shown in Tables 4 and 5. Example 9 Using the same reaction apparatus as in Example 1, 136.4 parts of the oligomer obtained in Example 1, 30.8 parts of 2-hydroxyethyl acrylate, 118.0 parts of IPDI and
After charging 0.40 parts of MEHQ and reacting at 75 to 80°C for 1 hour, 197.5 parts of the bifunctional acrylic ester compound obtained in Synthesis Example 3 was charged, and the reaction was continued for an additional 1 hour. Then, two drops of octyl stannous were added, and the mixture was stirred at the same temperature for 3 hours to react and obtain an oligomer. Performance evaluations were performed on the oligomers, and the results are shown in Tables 4 and 5. (Performance evaluation of clear cured film) (a) Preparation of cured film Various oligomers obtained in each Example, Synthesis Example 5 (Comparative Example 1) and Synthesis Example 6 (Comparative Example 2) 80
Part, trimethylolpropane triacrylate
20 copies and Darokyur 1173 (manufactured by Merck & Co., Ltd., 2
-Hydroxy-2-methyl-1-phenylpropan-1-one), coated on a tin plate with a bar coater to a film thickness of 20 μm, and cured by irradiating with ultraviolet rays under the following curing conditions. let 80W/cm x 1 lamp, distance from UV lamp 10cm, irradiation time 0.25 seconds (b) Performance evaluation method Curing speed: Time required for curing (seconds) Film hardness: Pencil hardness based on JIS-K-5400 Flexibility : Flexibility bending test based on JIS-K-5400 Film strength: Impact test based on JIS-K-5400 (Performance evaluation as ultraviolet curable printing ink) (1) Inking process Examples 1 to 9 and The various polyfunctional oligomers obtained in Comparative Examples 1 and 2, Carmine 6B, trimethylolpropane triacrylate, Darokyure 1173, and MEHQ were blended in the proportions shown in Table 4, kneaded with three rolls, and made into ink. Create various inks with a tack value of 11 to 13 when measured with a meter. (2) Ink performance evaluation method () Curability (curing time) 0.6g of ink was applied to an RI tester (manufactured by Mei Seisakusho Co., Ltd.)
Spread the color on carton paper using
After irradiating ultraviolet rays from a distance of 10 cm with an 80 W/cm high-pressure mercury lamp, press the double-sided special art paper with an RI tester and calculate the curing time as the irradiation time (seconds) required until the ink stops sticking. () Gloss of raw ink and emulsified ink The gloss of the cured printed matter obtained above (original ink gloss) was evaluated by visual observation. Also, after emulsifying 0.6g of ink and dampening water with an RI tester and draining, spread the color on carton paper.
Cured under the same conditions as when measuring original ink gloss,
The gloss of the printed surface after curing is defined as the gloss of the emulsified ink, and is similarly observed with the naked eye and evaluated according to the following criteria. (Standards) ◎: Very good ○: Good △: Between ○ and × ×: Poor () Misting Place paper in front of the roll of the inkometer and rotate the ink-covered roll 1200 times to mist the ink. The condition of the ink scattered on the paper surface is observed with the naked eye and evaluated using the following criteria. (Criteria) ○: Too little...suitable for use ×: Too much...not suitable for use () Cleanability Evaluate the cleanability of the ink meter roll with various types of ink using kerosene. () Storage stability Place the ink in a glass container, seal it tightly, leave it in an incubator (40℃), and measure the number of days until it polymerizes and solidifies.

【table】

【table】

【table】

[Table] *2: Azo red pigment [Effect of the invention] The photocurable oligomer obtained by the production method of the present invention can be applied to a wide range of applications by utilizing its photocurability, such as printing. When used as an ink binder, the resulting printing ink has a fast curing speed and is comparable to conventional solvent-based printing inks in terms of gloss, pigment dispersibility, printability, etc. has advantages. Therefore, the photocurable oligomer obtained by the production method of the present invention can be suitably used as a binder for printing inks, for example, a binder for overprint varnishes, a binder for paints, a solder resist, etc. .

Claims (1)

[Claims] 1. After reacting (a) a reaction product of (meth)acrylic acid and rosin glycidyl ester and (b) diisocyanates to obtain a compound having an isocyanate group at the terminal, (c) A method for producing a photocurable oligomer, which is characterized by reacting a reaction product of (meth)acrylic acid and diepoxides. 2. Reacting (a) a reaction product of (meth)acrylic acid and rosin glycidyl ester, (d) a hydroxyl group-containing acrylic ester, and (b) diisocyanates,
A method for producing a photocurable oligomer, which comprises obtaining a compound having an isocyanate group at its terminal, and then reacting the compound with (c) a reaction product of (meth)acrylic acid and a diepoxide.