JPS6219318B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a resin composition for surface treatment of offset printing blankets, which improves the ink transfer properties of offset printing blankets. In offset printing, printing is performed by first transferring the ink on the printing plate to a blanket, and then transferring it from the blanket to the printing paper. In order to have a uniform film thickness and to transfer the ink according to the pixels on the printing plate, This essentially requires that the surface of the blanket be smooth and have excellent ink receptivity. However, conventional blankets made of chloroprene rubber, nitrile rubber, thiokol, etc. do not necessarily have sufficient ink receptivity on the surface, and in order to improve the ink receptivity on the surface, the surface can be smoothed to improve the ink receptivity of the paper during printing. Banare becomes bad. When the paper is compressed between the blanket and the impression cylinder, the paper sticks to the blanket when it is held in the claws and pulled.
If you try to forcefully remove it by pulling it with your fingernails, the paper will stretch and cause misregistration, duplication, etc.
In order to avoid this, it is necessary to frequently fine-tune the printing press, which significantly impedes printing workability. For this reason, a method is generally used to improve paper curl by roughening the blanket surface, but in this case, the ink transfer from the blanket to the paper deteriorates and the outline of the printed image, especially the halftone dots, becomes unclear. become. In offset printing, subtle changes in the area of the halftone dots express changes in the shading of the image, so if the outline of the halftone dots becomes unclear, the finished print will become unclear, resulting in a blurred print with a lack of volume. For this reason, there is a limit to the improvement of paper imperfections by roughening the surface. As described above, conventional blankets have contradictory properties in that it is difficult to achieve both ink transferability and paper deterioration, and if one is emphasized, the other must be sacrificed. Therefore, in view of the above points, the present inventors
The present invention has been completed as a result of extensive research aimed at providing a blanket for offset printing that is excellent in both ink transferability and paper vanity. That is, the present invention comprises (A) a linear polyester containing hydroxyl groups at both terminals, (B) an organic polyisocyanate compound, (C) an addition-polymerizable unsaturated compound having an active hydrogen atom capable of reacting with the isocyanate group, and (D) polyoxy Mainly a mixture of an unsaturated polyester ether urethane resin obtained by reacting a polyhydric alcohol having an alkylene chain and an unsaturated polyether urethane resin obtained by reacting the components (B), (C), and (D). Regarding the resin composition for surface treatment of printing blankets contained as a component, by providing a cured film of the composition on the surface of offset printing blankets, ink transfer properties are dramatically improved compared to conventional blankets. Compared to conventional blankets, the solid areas of printing lines on printed materials printed with blankets are much more uniform and smooth, and the contours of halftone dots are clear and reproduced exactly as pixels. Although the surface is smooth, it is also excellent in paper curling, making it impossible to manufacture blankets that have no problems during printing. Component (A) used in the present invention, a linear polyester containing hydroxyl groups at both terminals, contains one or more acid components of aromatic, cycloaliphatic, and acyclic aliphatic dibasic acids and an ether bond in the molecule. It can be produced by reacting a dihydric alcohol that may be included. Examples of the dibasic acids include aromatic dibasic acids such as phthalic acid, phthalic anhydride, terephthalic acid, and isophthalic acid, cycloaliphatic dibasic acids such as tetrahydrophthalic anhydride, succinic acid, adipic acid, pimelic acid, and sebacin. acids, azelaic acid, maleic acid,
These anhydrides, acyclic aliphatic dibasic acids such as fumaric acid, citraconic acid, itaconic acid, etc.
Examples of dihydric alcohols include ethylene glycol, propylene glycol, triethylene glycol, 1,4-butadiol, 1,6-hexanediol, 2,2-diethylpropanediol,
Neopentyl glycol, diethylene glycol, triethylene glycol, butenediol,
Examples include 1,3-butylene glycol and 2,3-butylene glycol. The linear polyester containing hydroxyl groups at both ends of component (A) obtained using these raw materials has a number average molecular weight of
Preferably, it falls within the range of 500 to 4000. This polyester can be produced according to a commonly used method for producing polyester resins. Examples of the organic polyisocyanate compound of component (B) include 2,4-tolylene diisocyanate,
Aromatic diisocyanates such as 2,6-tolylene diisocyanate, mixtures of these isomers, P-xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, cyclohexane-1.
3-(or 1,4) diisocyanate, 1-isocyanate 3-isocyanatomethyl-3,5,5
Examples include cycloaliphatic diisocyanates such as -trimethylcyclohexane, isophorone diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate, and acyclic aliphatic diisocyanates such as hexamethylene diisocyanate and tetramethylene diisocyanate. Examples of addition polymerizable unsaturated compounds having an active hydrogen atom capable of reacting with the isocyanate group of component (C) include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate. Acrylate, diethylene glycol mono(meth)acrylate, triethylene glycol mono(meth)acrylate, trimethylolpropane di(meth)acrylate, pentaerythritol tri(meth)
Examples include hydroxyl group-containing compounds obtained by reacting acrylate, N-methylol (meth)acrylamide, (meth)acrylamide, glycidyl (meth)acrylate with a fatty acid or the above-mentioned dibasic acid. The polyhydric alcohol having a polyoxyalkylene chain as component (D) includes, for example, polyhydric alcohols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, glycerin, trimethylolpropane, triethanolamine, etc., added with ethylene oxide or propylene oxide. Examples include the body. These polyhydric alcohols preferably have a number average molecular weight in the range of 200 to 4,000. When producing the unsaturated polyester ether urethane resin and unsaturated polyether urethane resin of the present invention by reacting each of the above-mentioned components, the ring structure content concentration and addition polymerizable unsaturated group content concentration contained in the resulting resin are as follows. This is an important factor that affects the durability and printability of blankets whose surface has been treated with a mixture of resins. That is, in the unsaturated polyester ether urethane resin, the ring structure content concentration (the number of monocyclic or condensed polycyclic molecules contained in 1 g of resin) is 1.0 × 10 ^-3 to 3.0 × 10 ^-3 mol/g.
The concentration of addition polymerizable unsaturated groups (number of molecules of addition polymerizable unsaturated groups contained in 1 g of resin) is preferably in the range of 0.2×10 ⁻³ to 1.0×10 ⁻³ mol/g. In addition, in unsaturated polyether urethane resin, the ring structure content concentration is 0.5 × 10 ^-3 ~ 1.5
The range of ×10 ^-3 mol/g is preferable, and the concentration of addition polymerizable unsaturated groups is 0.5 × 10 ^-3 to 1.5 × 10 ^-3 mol/g.
A range of is preferred. If the ring structure content concentration of the above two resins is below the lower limit of the above range, ink piling is likely to occur during printing, and if it exceeds the upper limit, cracks in the treated film or thickening of halftone dots may occur during printing, resulting in an uneven print image. There is a tendency to exceed the decline in quality. The above-mentioned ink piling refers to paper powder adhering to the plate surface during printing, spray powder to prevent dust from setting off, etc., which separates from the plate surface and does not transfer to the paper, and eventually forms clumps and leaves traces on the printing paper. This is a troublesome phenomenon that seriously damages printed images, and it always occurs to varying degrees in commonly used blankets. Furthermore, if the concentration of addition-polymerizable unsaturated groups in the two resins exceeds the upper limit, the crosslinking density will be too high, making the coating film brittle and prone to cracking, while below the lower limit, the curing speed will be slow and The crosslinking density is too low, resulting in a weak coating, which tends to cause ink piling during printing. Method 1 for producing an unsaturated polyester ether urethane resin of the present invention in which the ring structure and the content concentration of addition polymerizable unsaturated bonds are each within the above-mentioned preferred ranges.
For example, the acid component having a molar ratio of cyclic dibasic acid/acyclic dibasic acid in the range of 10/90 to 30/70 is reacted with the dihydric alcohol component to achieve a number average molecular weight of 500. ~4000 hydroxyl group-containing linear polyester is produced, and the organic polyisocyanate 2 having one ring structure per equivalent of this polyester is prepared.
It is produced by reacting 1/2 equivalent of the active hydrogen atom-containing addition-polymerizable unsaturated compound, and further reacting 1/2 equivalent of the polyhydric alcohol having a polyoxyalkylene chain. be able to. The number average molecular weight of the unsaturated polyester ether urethane resin used in the present invention is
The range is preferably 4000 to 17000. In addition, an example of the production of the unsaturated polyether urethane resin of the present invention in which the content concentration of the ring structure and the addition polymerizable unsaturated bond falls within the above-mentioned preferred range is as follows: It can be produced by reacting 1 equivalent of polyhydric alcohol with 1.2 to 2 equivalents of the organic polyisocyanate, and then reacting this with 1 equivalent of the active hydrogen atom-containing addition polymerizable unsaturated compound. The number average molecular weight of the unsaturated polyurethane resin used in the present invention is preferably in the range of 1,000 to 7,000. When producing the resin, a known catalyst may be added as necessary. Examples of the catalyst include dibutyltin dilaurate, dibutyltin oxide, acetylacetone iron salt, triethylamine tributylamine, sodium acetate, and lithium acetate. Further, a polymerization inhibitor may be added to suppress thermal polymerization during the reaction or dark reaction during storage of the obtained resin. As a polymerization inhibitor,
Examples include hydroquinone, tert-butylhydroquinone, benzoquinone, 2,4-tert-butylhydroxytoluene, N.N-diphenylnitrosamine, 2,6-di-tertbutyl-P-cresol, and hydroxyanisole. If the viscosity of the reaction mixture increases during the reaction, adjust the viscosity of the reaction system by gradually adding a solvent such as acetone, a ketone such as methyl ethyl ketone, or an ester such as ethyl acetate as necessary. Good too. A resin composition containing a mixture of an unsaturated polyester ether urethane resin and an unsaturated polyether urethane resin as a main component obtained as described above is uniformly applied to a blanket for offset printing.
The mixing ratio of unsaturated polyester ether urethane resin and unsaturated polyether urethane resin is the former/
The latter weight ratio is 90/10 to 10/90, preferably 90/
A ratio of 10 to 50/50 is appropriate. Within this mixing ratio range, piling of ink on the processing blanket is most effectively prevented. Although the two types of resins used in the present invention cannot prevent ink piling when used alone, this can be prevented by using a mixture of these two types. The resin composition obtained by mixing as described above is applied to the surface of an offset printing blanket and cured. As a means for curing, thermal curing using infrared rays or the like, curing with high energy rays such as actinic rays, electron beams, etc. can be used. During curing, a polymerization initiator can be used if necessary. In the case of thermal curing, for example, benzoyl peroxide, kyumene hydroperoxide, t-butyl hydroperoxide, azobisisobutyronitrile, etc. can be used as a thermal polymerization initiator, and in the case of curing with actinic rays, Examples of photopolymerization initiators include benzoin, benzoin methyl ether, benzoin isopropyl ether, naphthoquinone, anthraquinone, benzophenone, acetophenone, 2
-Hydroxy-2-methylpropiophenone, Michler's ketone, P-dimethylaminobenzaldehyde, P-dimethylaminoacetophenone, azobisisobutyronitrile, and the like can be used. When applying the composition of the present invention to the blanket surface, the above-mentioned suitable polymerization initiator is mixed with the composition as necessary, and the composition is dissolved in an appropriate solvent to adjust the viscosity to be easy to apply. It may be applied uniformly to the blanket surface by spin coating, roll coating, doctor coating, spray coating, or the like, and the solvent may be evaporated. The appropriate thickness of the surface coating film is approximately 5 to 40 microns.
Suitable solvents used for the above purpose include ester-based solvents such as ethyl acetate, and ketone-based solvents such as acetone and methyl ethyl ketone. For curing the coating film thus obtained, heat or high-energy radiation can be used as described above. In the case of thermosetting, suitable conditions for curing include a heating temperature of 50 to 150°C and a heating time of 1 to 20 hours. When using active light, the wavelength range is 250 ~
It is desirable to use a 700 nm light source. Low-pressure mercury lamps, high-pressure mercury lamps, fluorescent lamps, xenon lamps, carbon arc lamps, tungsten incandescent lamps, and the like can be used. The irradiation time depends on the type of light source, output, irradiation distance, etc., but is within a few seconds to 10 minutes. Electron accelerators used for curing with electron beams include Kotskucroft type, Kotscroft-Walton type, Vandegrack type, resonant transformer type, insulated core transformer type, dynamitron type, and high frequency type. 100~200Kev
The coating film is irradiated with an electron beam with an acceleration energy of . EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the scope of the present invention is not limited thereby. Production example 1 219.2 parts of adipic acid, 222.2 parts of phthalic anhydride,
355 parts of 1,6-hexanediol and 62 parts of ethylene glycol were placed in a reaction vessel, and the temperature was raised to 240°C.
The reaction proceeded by raising the temperature over a period of time and removing water generated as the condensation reaction proceeded from the system. After raising the temperature to 240°C, the reaction was further carried out for 1 hour, and then under reduced pressure of 160 mmHg for another 1 hour. After confirming that the acid value had become 1, the reaction was stopped, and the number average molecular weight was 770 after being cooled. of polyester-
I got (). Production Example 2 438.4 parts of adipic acid, 355 parts of 1,6-hexanediol, and 62 parts of ethylene glycol were placed in a reaction vessel, and the temperature was gradually raised to 240°C over about 3 hours. The reaction proceeded while removing the water from the system. After raising the temperature to 240℃, reacting for another hour, and then under reduced pressure of 160 mmHg for another hour, and confirming that the acid value was 1, the reaction was stopped and cooled to prepare a polyester with a number average molecular weight of 750. I got it. Production example 3 277.7 parts of adipic acid, 1,4-butanediol
108.1 parts of ethylene glycol and 62 parts of ethylene glycol were placed in a reaction vessel, and the temperature was gradually raised to 240°C over about 3 hours, and the reaction proceeded while removing water generated as the condensation proceeded from the system. After raising the temperature to 240°C, the reaction was further carried out for 1 hour, and then the reaction was carried out for 2 hours under a reduced pressure of 10 mmHg. After confirming that the acid value was 1, the reaction was stopped and cooled to form a polyester with a number average molecular weight of 2000. I got (). Production Example 4 233 parts of polyester-() obtained in Production Example 1 and 133 parts of isophorone diisocyanate were placed in a reaction vessel and reacted at 80°C for 2 hours, followed by 0.3 part of hydroquinone and 38 parts of 2-hydroxyethyl acrylate.
The temperature was raised to 100°C, and the reaction was continued for an additional hour while blowing air. Next, Sanyo Kasei Co., Ltd. Newpol GP600 (molecular weight of glycene adduct with ethylene oxide about 600)
60 parts were added and kept at 100℃. After 4 hours of reaction,
The reaction was terminated when the remaining amount of NCO groups reached 0.03%, and after cooling, 150 parts of methyl ethyl ketone was added. The obtained resin had a number average molecular weight (Mn) = 4600,
Ring structure content concentration (R) = 2.3 × 10 ^-3 mol/g, addition polymerizable unsaturated group content concentration (U) = 0.66 × 10 ^-3
It was mol/g. Production Example 5 Polyester obtained in Production Example 1-()154
75 parts of polyester-() obtained in Production Example 2,
133 parts of isophorone diisocyanate was placed in a reaction vessel and reacted at 80°C for 1.5 hours, then 0.3 parts of hydroquinone and 38 parts of 2-hydroxyethyl acrylate were added, the temperature was raised to 100°C, and the reaction was continued for an additional 2 hours while blowing air. Ta. Next, 40 parts of Newpol T-P400 (propylene oxide adduct of trimethylolpropane, average molecular weight 400) manufactured by Sanyo Kasei Co., Ltd. was added and kept at 100°C. After 5 hours of reaction, the reaction was terminated when the remaining amount of NCO groups reached 0.04%, and after cooling, 130 parts of methyl ethyl ketone was added. The obtained resin has Mn=4400 and R=2.1×10 ^-3
Mol/g U=0.69×10 ⁻³ mol/g. Production Example 6 Polyester obtained in Production Example 1-()154
200 parts of polyester-() obtained in Production Example 3,
133 parts of isophorone diisocyanate was placed in a reaction vessel and reacted at 80°C for 2 hours, then 0.3 parts of hydroquinone and 2-hydroxyethyl acrylate were added.
The mixture was heated to 100°C and reacted for 2 hours while blowing air. Next, Sanyo Chemical Industries Co., Ltd.
100 parts of Newpol GP1000 (propylene oxide adduct of glycene, average molecular weight 1000) and 0.1 part of acetylacetone iron salt were added and kept at 100°C. After 3 hours, the reaction was terminated when the remaining amount of NCO group reached 0.02%, and after cooling, methyl ethyl ketone was added.
Added 190 copies. The obtained resin had Mn=6200, R=
1.45×10 ⁻³ mol/g, U=0.48×10 ⁻³ mol/g. Manufacturing example 7 PPG DiOL-1000 manufactured by Mitsui Nisso Polyurethane Co., Ltd.
(Polypropylene glycol average molecular weight 1000)
300 parts of isophorone diisocyanate and 133 parts of isophorone diisocyanate were placed in a reaction vessel, and the temperature was raised to 60°C. Then, 0.1 part of dibutyltin dilaurate was added, and the temperature was raised to 80°C. React at 80°C for 1 hour, then add 0.3 parts of hydroquinone,
Add 77 parts of 2-hydroxyethyl acrylate.
The temperature was raised to 100°C, and the reaction was carried out for 6 hours while blowing air. The reaction was terminated when the remaining amount of NCO groups reached 0.01%, and after cooling, 51 parts of methyl ethyl ketone was added. Resin obtained Mn=1700, R=1.19×
^10-3 , U=1.19× ^10-3 . Example 1 100 parts of the resin solution obtained in Production Example 4, 85 parts of the resin solution obtained in Production Example 7, 8 parts of benzophenone, 8 parts of P-dimethylaminobenzaldehyde, and 10 parts of 2-hydroxy-2methylpropiophenone were added to methyl ethyl ketone. 1000 parts of the solution was mixed to form a solution, which was uniformly applied onto a commercially available blanket for offset printing by a spin coating method, and heated at 90°C for 20 minutes to volatilize the solvent. The coating thickness was 11μ. This was irradiated with light for 20 seconds from a distance of 12 cm using a high-pressure mercury lamp with an output of 80 W/cm ² manufactured by Hanovia, Inc. in the United States, to obtain a surface-treated blanket. Example 2 100 parts of the resin solution obtained in Production Example 5, 37 parts of the resin solution obtained in Production Example 7, 4 parts of benzophenone, 4 parts of P-dimethylaminoacetophenone, 5 parts of 2-hydroxy 2-methyl-propiophenone A solution was prepared by mixing 500 parts of methyl ethyl ketone with 500 parts of methyl ethyl ketone, and the solution was uniformly applied to a commercially available offset printing blanket using a spin coating method, and then heated at 90°C.
The mixture was heated for 20 minutes to volatilize the solvent. The coating thickness was 14μ. This was irradiated with light for 20 seconds from a distance of 12 cm using a high-pressure mercury lamp with an output of 80 W/cm ² manufactured by Hanovia Inc. in the United States, to obtain a surface-treated blanket. Example 3 100 parts of the resin solution obtained in Production Example 6, 85 parts of the resin solution obtained in Production Example 7, 8 parts of benzophenone, 8 parts of P-dimethylaminobenzaldehyde, and 10 parts of 2-hydroxy-2methyl-propiophenone were added. Mix it with 1000 parts of methyl ethyl ketone to make a solution, apply this uniformly onto a commercially available offset printing blanket by spin coating, and heat it at 90℃ for 20 minutes.
The mixture was heated for 1 minute to evaporate the solvent. The coating thickness was 12μ. This was irradiated with light for 20 seconds from a distance of 12 cm using a high-pressure mercury lamp with an output of 80 W/cm ² manufactured by Hanovia Inc. in the United States, to obtain a surface-treated blanket. Example 4 100 parts of the resin solution obtained in Production Example 4, 85 parts of the resin solution obtained in Production Example 7, azobisisobutyronitrile
1.4 parts were dissolved in 1000 parts of methyl ethyl ketone to form a solution, which was spin-coated onto a commercially available offset printing blanket and left at room temperature for 24 hours to volatilize the solvent. The coating thickness was 10μ. This was heated and cured in an oven at 100° C. for 2 hours to obtain a surface-treated blanket. Example 5 100 parts of the resin solution obtained in Production Example 4 and 85 parts of the resin solution obtained in Production Example 7 were dissolved in 500 parts of methyl ethyl ketone to obtain a solution, which was spin-coated onto a commonly available offset printing blanket. The solution was applied uniformly by the method and heated at 90°C for 20 minutes to volatilize the solvent. The coating thickness was 14μ. This is done using a transformer electron accelerator with an electron beam energy of 300KV and an electron beam current of 45
A surface treated blanket was obtained by irradiation with an electron beam at a mA dose of 10 Mrad. The surface-treated blankets obtained in the examples and the untreated blankets used as comparative examples were each attached to an offset printing machine Favorit RF-01 manufactured by Mann-Roland, West Germany, and offset printing was performed as usual. The ink is from Dainippon Ink Chemical Industry Co., Ltd.
New Champion Super APEX Beni manufactured by New York was used. The printing results are shown in the table below. The printing results were evaluated using the following items. (1) Ink receptivity (smoothness, uniformity) of solid areas on coated paper (2) Ink receptivity (smoothness, uniformity) of solid areas on high-quality paper
(3) Outline of halftone dots on coated paper (4) Outline of halftone dots on wood-free paper (5) Thickening of halftone dots on coated paper and wood-free paper (6) Piling of ink on blanket (7) Paper Banare property (degree of paper curl)

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Claims (1)

[Scope of Claims] 1 (A) a linear polyester containing hydroxyl groups at both terminals, (B) an organic polyisocyanate compound, (C) an addition-polymerizable unsaturated compound having an active hydrogen atom capable of reacting with isocyanate groups, and (D) An unsaturated polyester ether urethane resin obtained by reacting a polyhydric alcohol having a polyoxyalkylene chain, and (B),
A resin composition for surface treatment of printing blankets containing as a main component a mixture with an unsaturated polyether urethane resin obtained by reacting components (C) and (D). 2 The concentration of the cyclic structure contained in the molecules of the unsaturated polyester ether urethane resin is 1.0×
10 ^-3 to 3.0 x 10 ^-3 mol/g, and a patent in which the concentration of the cyclic structure contained in the molecules of the unsaturated polyether urethane resin is 0.5 x 10 ^-3 to 1.5 x 10 ^-3 mol/g. A composition according to claim 1. 3 The content concentration of the addition polymerizable unsaturated group contained in the molecule of the unsaturated polyester ether urethane resin is 0.2 × 10 ^-3 to 1.0 × 10 ^-3 mol / g, and the concentration of the addition polymerizable unsaturated group contained in the molecule of the unsaturated polyether urethane resin is The concentration of added polymerizable unsaturated groups is 0.5×10 ^-3 ~1.5×
10 ^-3 mol/g of the composition according to claim 1. 4 Unsaturated polyester ether urethane resin/
Mixing weight ratio of unsaturated polyether urethane resin
The composition according to claim 1, which has a ratio of 90/10 to 10/90. 5. The composition according to claim 1, wherein the linear polyester containing hydroxyl groups at both terminals has a number average molecular weight of 500 to 4,000, and the unsaturated polyester ether urethane resin obtained using the same has a number average molecular weight of 4,000 to 17,000. thing. 6. The composition according to claim 1, wherein the unsaturated polyether urethane resin has a number average molecular weight of 1,000 to 7,000.