JPS5842495A - Resin composition for surface treatment of blanket for printing - Google Patents

Abstract

PURPOSE:To obtain a resin composition having excellent ink transferability and excellent paper separability by reaction of a specific linear polyester, a polyisocyanate compound, an addition polymerizable unsaturated compound, and a polyhydric alcohol. CONSTITUTION:A liner polyester (A) having hydroxyl groups on its both ends and a number average molecular weight of 500-4,000, obtained from a dibasic acid and a divalent alcohol, an organic polyisocyanate compound (B) (e.g., isophorone diisocyanate, etc.), an ethylenic unsaturated compound (C) with active hydrogen reactive to isocyanate group (e.g., 2-hydroxyethyl acrylate, etc.), and a polyhydric alcohol (D) (e.g., 3-methylpentane, 1,3,5-triol, etc.) are reacted to obtain an objective resin composition composed of an unsaturated urethane resin having a number average molecular weight of 4,000-17,000 and a concentration of ring structure of 0.5X10<-3>-3.0X10<-3>mol/g as main component.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resin composition for surface treatment of an offset printing blanket that improves the ink transfer properties of the offset printing blanket.

Therefore, printing is performed, and in order to have a uniform film thickness and to transfer ink in accordance with the pixels on the printing plate, it is essential that the surface of the blanket be smooth and have excellent ink receptivity. However, conventional blankets made of chloroprene rubber, nitrile rubber, thiocol, etc. do not necessarily have sufficient ink receptivity on the surface, and if the surface is smoothed to improve the ink receptivity,
Paper curling becomes worse when printing. When paper banare goes bad,
After the paper is compressed between the blanket and the impression cylinder, when it is pulled between the nails, the paper sticks to the blanket.
If you try to forcefully remove it by pulling it with your nails, the paper will stretch, causing misregistration, duplication, etc. To avoid this, it will be necessary to make frequent fine adjustments to the printing machine, and therefore the printing process will be difficult. Sexuality is severely inhibited.

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 that lacks a sense of volume. For this reason, there is a limit to the improvement of paper thinning by roughening the surface.

As described above, it is difficult for conventional blankets to achieve both ink transferability and paper damage; they have contradictory properties such that if one is emphasized, the other must be sacrificed.

Therefore, in view of the above points, the present inventors conducted intensive research and came up with the present invention, with the aim of providing an offset printing blanket that is excellent in both ink transferability and paper vane resistance. .

That is, the present invention comprises a linear polyester containing fA1 hydroxyl groups at both ends, fB) an organic polyisocyanate compound, and (C)
Resin mold 1 for surface treatment of printing blankets containing as a main component an unsaturated urethane resin obtained by reacting an ethylenically unsaturated compound having an active hydrogen atom capable of reacting with an isocyanate group and a polyhydric alcohol Regarding the composition, by applying the composition to the surface of an offset printing blanket and curing it, the paint transfer properties compared to conventional blankets are dramatically improved, and the print lines of printed matter printed with this blanket are improved. The ink on the solid areas is very even and smooth compared to the conventional blanket, and the halftone dot contours are clear and reproduced exactly as the image.
Furthermore, even though the surface of the blanket is smooth, it has excellent paper alignment, making it possible to manufacture blankets that do not have the same order at the time of printing.

The linear polynisdel containing hydroxyl groups at both ends of the component fA) used in the present invention has one or more acid components of aromatic dibasic acids, cyclic aliphatic dibasic acids, and acyclic aliphatic dibasic acids. It can be produced by reacting an ether with a dihydric alcohol which may contain a 5-bond in its molecule. Examples of aromatic dibasic acids include phthalic acid, 7-thalic anhydride, terephthalic acid,
Cyclic aliphatic dibasic acids such as isophthalic acid, such as tetrahydrophthalic anhydride; acyclic aliphatic dibasic acids, such as succinic acid, adipic acid, pimelic acid, sebacic acid, azelaic acid, maleic acid, and their anhydrides; , 7-marinated alcohol, citraconic acid, itaconic acid, etc., and dihydric alcohols such as ethylene glycol, phlopylene gellicol, diethylene glycol, diethylene glycol, triethylene glycol, tripropylene glycol, 1.4-7"tanediol, 1, Examples include 6-hexanediol, 2,2-diethylpropanediol, neopentyl glycol, diethylene glycol, triethylene glycol, phtendiol, 1,3-butylene glycol, and 2,6-butylene glycol. A) A type of dihydric alcohol containing linear ether bonds containing hydroxyl groups at both ends can be used, but the concentration of ether bonds contained in the unsaturated urethane resin according to the present invention must be maintained at a constant concentration as described below. If the temperature exceeds 100%, blankets surface-treated with such resins tend to cause ink piling during printing. This is a troublesome phenomenon in which particles such as subilet powder leave the printing plate and do not transfer to the paper, but end up clumping and leaving traces on the printing paper, seriously damaging the printed image. Therefore, it is necessary to prevent such ink piling, but to do so, it is necessary to use a dihydric alcohol that does not have an ether bond as the alcohol component of polynisdel, or to use an ether. It is preferable to use a dihydric alcohol in which the number of bonds, if any, is two or less in one molecule.

The linear polyester containing hydroxyl groups at both ends of component (A) obtained using the above raw materials has a number average molecular weight of 500 to 4000.
Preferably. This polyester may be manufactured according to conventional methods for manufacturing polyester resins.

As the organic polyisocyanate of fB) component, for example, 2
, 4-tolylene diisocyanate, 2. (S-)lylene diisocyanate, mixtures of these isomers, aromatic diisocyanates such as p-xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, cyclohexane-1
, 3(or 1,4)-diisocyanate, 1-incyanate-3-isocyanatomethyl-6,5,5-)limethylcyclohexane, cycloaliphatic diisocyanate such as isophorone diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate Examples include acyclic aliphatic diisocyanates such as.

Examples of the addition-polymerizable ethylenically unsaturated compound having an active hydrogen atom capable of reacting with the isocyanate group of component fc) include 2-hydroxyethyl (meth)acrylate, 2
-Hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, diethylene glycol mono(meth)acrylate, triethylene glycol mono(meth)acrylate, trimethylolpropane di(meth)acrylate, pentaerythritol tri(
Hydroxyl group-containing compounds obtained by reacting meth)acrylate, N-methylol(meth)acrylamide, acrylamide, glycidyl(meth)acrylate with fatty acids or the dibasic acids mentioned above can be used.

Examples of the polyhydric alcohol of component (D) include ethylene glycol, propylene glycol, diethylene glycol, diethylene glycol, triethylene glycol, tripropylene glycol, 1,4-butanediol, 1,6-hexanediol, 2, 2-diethylpropanediol, obentyl glycol, diethylene glycol, triethylene glycol, butynediol, 1
, 3-butylene glycol, dihydric alcohols such as 2,6-butylene glycol, glycerin, trimethylolpropane, 1,2,6-hexanediol, 6-methylpentane, 1,3,5-trioluna Examples include tetrahydric alcohols such as trivalent alcohol and pentaerythritol.

(2) A polyhydric alcohol containing needle bonds in the molecule can be used as a component, but if the concentration of ether bonds contained in the resulting unsaturated urethane resin exceeds a certain concentration, the above-mentioned ink Piling tends to occur.

Polymer 11j which does not have a Needel bond as a component)
It is preferable to use an f+ alcohol or a polyhydric alcohol having at most two ether bonds in one molecule, if at all.

In any case, the above (A), (B), fc) and)
The concentration of ether bonds contained in the unsaturated urethane resin obtained by reacting the components is i, 4X10-3 mol/, 9 (
It is extremely effective to prevent ink piling if the number of 10-bond molecules contained in 1 g of resin is as follows.

When producing the unsaturated urethane resin of the present invention by reacting each of the above-mentioned components, the ring structure content concentration and the additive unsaturated bond content concentration contained in the resulting resin are determined by the ether bond metal ambiguity. Similarly, it is an important factor that affects the durability and printability of blankets whose surface has been treated with this resin. That is, the ring structure content concentration (the number of monocyclic or fused polycyclic molecules contained in 1 g of resin) is preferably [ ], 5
X10-s to 3, DXID-3 mol/g, more preferably a range of 1.5 If it is lower than 3, it is easy to cause ink piling during printing.
．． If it exceeds 0.times.10"-" mol/g, cracks in the treated film or thickening of halftone dots will occur during printing, and the quality of the printed image will tend to deteriorate. In addition, the concentration of polymerizable unsaturated bonds (the number of molecules of unsaturated bonds contained in the resin 1y) according to Appendix '710 is preferably 0.5X10-3 to 2.0X10-3 mol/
g more preferably 0.5XID-3 to 1. OXl[1-
'The range of mol/I is suitable, 0.5XID4 mol/I
If it is less than 2.0 x 10-' mol/g, the hardness rate is slow, and the crosslinking density is too low, making the coating film soft and easy to cause ink piling during printing. If it is too long, cracks in the coating film or thickening of halftone dots are likely to occur. It is preferable to have a high content of ring structures, ether bonds, and addition-polymerizable unsaturated bonds! +> An example of the method for manufacturing the unsaturated urethane resin of the present invention that falls within the range is cyclic dibasic acid/1 (the molar ratio of mocycloaliphatic dibasic acid is 10/90 to 1).
The acid component in the range of 50,150 is reacted with the dihydric alcohol component having the following number of Needel bonds in the molecule to form a number average molecule! A linear polyester containing 500 to 40,000 hydroxyl groups at both ends is produced, one part of this polyester is reacted with two parts of the organic isocyanate having one ring structure, and then the above-mentioned active hydrogen atom-containing addition is added to the polyester. It can be produced by reacting 1/2 equivalent of a polymerizable unsaturated compound and further reacting 172 equivalents of the polyhydric alcohol containing 2 or less ether bonds in the molecule. The number average molecular pupil of the unsaturated urethane resin used in the present invention is preferably in the range of 4,000 to 16-17,000.

During production, a known catalyst may be added as necessary. Examples of the catalysts used include dibutyltin dilaurate, dibutyltin oxide, acetylacetone iron salt, triethylamine tributylamine, sodium acetate, and lithium acetate. In addition, to suppress thermal polymerization during reaction or dark reaction during storage of the obtained resin,
A polymerization inhibitor may also be added. Examples of polymerization inhibitors include hydroquinone, tart-butylhydroquinone, benzoquinone, 2,4-tert-butylhydroxytoluene, N,N-diphenylnitronamine, 2,
Examples include 6-tert-butyl-p-cresol and hydroxyanisole.

If the viscosity of the reaction system increases during the reaction, adjust the viscosity of the reaction system by gradually adding solvents such as acetone, ketones such as methyl ethyl ketone, and esters such as ethyl acetate as necessary. You may. The composition obtained by the above method is uniformly applied to the surface of an offset printing blanket and cured. As the curing means, heat curing using infrared rays or the like, curing method using high energy rays such as actinic rays, electron beams, etc. can be used. A polymerization initiator may be used if necessary during curing. In the case of thermal curing, for example, benzoyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, azobisisobutyronitrile, etc. can be used as a thermal polymerization initiator, and in the case of curing with actinic rays, for example, light As a polymerization initiator, benzoin, acyloin, benzoin methyl ether, benzoin isopropyl ether, naphthoquinone, anthraquinone, benzophenone, acetophenone, 2-hydroxy-2-methylglopiofenone, Michler's ketone,
p-dimethylaminobenzaldehyde, p-dimethylaminoacetophenone, azobisisobutyronitrile, etc. can be used.

When applying the #I 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. This may be uniformly applied to the blanket surface by a method such as spin coating, roll coating, doctor coating, or spray coating, and the solvent may be volatilized. The appropriate thickness of the surface coating film is approximately 5 to 40 microns. As the solvent used for the above purpose, ester-based solvents such as ethyl acetate, and ketone-based solvents such as acetone and methyl ethyl ketone are suitable.

For curing the coating film thus obtained, heat or high-energy radiation can be used as described above. In the case of thermosetting, the curing conditions are a heating temperature of 50 to 150'C1
A heating time of 1 to 20 hours is equivalent to 211i. When using active light, it is desirable to use a light source with a wavelength range of 250 to 700 nm. For example, a low pressure mercury lamp, a high pressure mercury lamp, a fluorescent lamp, a xenon lamp, a carbon arc lamp, a tungsten incandescent lamp, etc. can be used. The irradiation time depends on the type and output of the light source, the irradiation distance, etc., but it takes a few seconds to
Within 10 minutes.

Electron accelerators used for curing with electron beams include Kotscroft type, Kotscroft-Walton type, Pandegraak type, resonant transformer type, insulated core transformer type, dynamidron type, and high frequency type. The coating film is irradiated with an electron beam having an acceleration energy of 100 to 200 keys.

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 2192 parts of adipic acid, 222.2 parts of 7-talic anhydride, 355 parts of ~17-1,6-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 the water generated as the condensation reaction proceeded was taken out of the system.

After raising the temperature to 240°C and reacting for another 1 hour, 160°C
11! The reaction was further carried out under reduced pressure of Hg for 1 hour, and after confirming that the acid value became 1, the reaction was stopped and cooled to obtain polyester fIl having a number average molecular weight of 770.

Production Example 2 Adipine [438, 4 parts, 1,6-hexanediol 3
55 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 6 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 continued for 1 hour, and then for another 1 hour under a reduced pressure of 160111H, V. After confirming that the acid value was 1 to 18-, the reaction was stopped and cooled to reduce the number average molecular weight to 7.
50 polyester layers were obtained.

Production Example 6 1277.7 parts of Adivin I', 108.1 parts of 1,4-butanediol, and 62 parts of ethylene glycol were placed in a reaction vessel and the temperature was gradually raised to 240°C over about 6 hours.
l! As the process progressed, the water generated was removed from the system and the reaction proceeded. After raising the temperature to 240°C and reacting for an additional hour, the reaction time was 10mmH,! The reaction was carried out for 2 hours under reduced pressure of i', and after confirming that the acid value was 1, the reaction was stopped and cooled to prepare a polyester with a number average molecular weight of 2100.
I got Gill 'lc'.

Example 1 233 parts of polyester-(I) obtained in Production Example 1 and 166 parts of isophorone diisocyanate were placed in a reaction vessel and
The reaction was carried out at ℃ for 2 hours, and then 06 parts of hydroquinone and 38 parts of 2-hydroxyethyl acrylate were added.
The temperature was raised to 00°C, and the reaction was continued for an additional 1.5 hours while blowing air. Next, 13.4 parts of methylpentane 1,3.5-triol was added and kept at 100°C, and as the viscosity of the reaction system increased as the reaction progressed, 15 parts of ethyl acetate was added.
Mix the parts and react for 4 hours while adjusting the viscosity.
The reaction was terminated when the COC residue amount reached 0.06%, and after cooling, 120 parts of methyl ethyl ketone was added. The obtained resin had a number average molecular weight (Mn) of -4200, a ring structure content concentration (R) of -2,5X 10-3 mol/g, an ether bond content concentration (E) of -〇, 7X10'-3 mol/I, Additive polymerizable unsaturated bond content concentration (U) = 0.7x1o-3
It was mol/g. Resin solution thus obtained 100
parts, benzophenone 4 parts, p-dimethylaminobenzaldehyde 4 parts, 2-hydroquine-2-methylpropiophenone (Darogure 1173, manufactured by Merck & Co., West Germany) 5
of fermentation liquid mixed with 500 parts of methyl ethyl ketone,
The mixture was uniformly coated on a commercially available offset printing blanket by a spin coating method, and heated at 90° C. for 20 minutes to volatilize the solvent. The coating thickness was 12μ. This was irradiated with light for 20 seconds from a distance of 12 mm using a high-pressure mercury lamp with an output of 80 w/cm, manufactured by Hanovia, Inc. in the United States, to obtain a surface-treated blanket.

Example 2 93 parts of the polyester fr) obtained in Production Example 1, 180 parts of the polyester flI) obtained in Production Example 2, and 4160 parts of inphorone diisocyanate were placed in a reaction vessel, reacted at 80°C for 3 hours, and then Hydroquinone 03? 46 parts of fB, 2-hydroxyethyl acrylate was added, the temperature was raised to 100°C, and the mixture was reacted for 2 hours while blowing air. Next, methylpentane-1.3.5-)liol 162
was kept at 100°C. After 4 hours, there was no NCO group residue.
．． The 21-reaction was terminated when the temperature reached 0.3%, and after cooling, 154 parts of methyl ethyl ketone was added. The obtained resin had Mn=4100 and R=1.8.
X10-”mol/i, E=Omol/&, U=0.7
X 1 []-3 mol/g.

100 parts of the resin solution thus obtained, 4 parts of benzophenone, 4 parts of p-dimethylaminoacetophenone, 2-
A solution of 5 parts of hydroxy-2-methyl-propiophenone mixed with 500 parts of methyl ethyl ketone was uniformly coated on a commercially available offset printing blanket using a spin coating method, and heated at 90°C for 20 minutes to remove the solvent. was vaporized. The coating thickness was 10μ. To this, I used a high-pressure mercury lamp with an 80w/α2 output made by Hafbia, Inc.
A surface treated blanket was obtained by irradiating light for 20 seconds from a distance of .

Example 6 155 parts of polynisdel-m obtained in Production Example 1, Production Example 32
2- 210 parts of the polyester-dll obtained in step 2) and 153 parts of isophorone diisocyanate were placed in a reaction vessel and reacted at 80°C for 1.5 hours, followed by 0.3 part of hydroquinone and 38.3 parts of 2-hydroxyethyl acrylate. The mixture was heated to 100°C and reacted for 1.5 hours while blowing air. Then trimethylolpropane 16.
Add 4 parts and 0.1 part of dibutyltin dilaurate to 100
It was kept at ℃. After 4 hours, the reaction was terminated when the NCO group residue reached 0.05%, and after cooling, methyl ethyl ketone was added.
174 parts were added to obtain resin solution (2).

The obtained resin had Mn=5600. R=1.69X
10-' -EJIi/g, E=O mol/i, U=0
．． 56 x 10-'' moles/g.

10 [] parts of the resin solution thus obtained, 4 parts of benzophenone, 4 parts of p-dimethylaminobenzaldehyde,
A solution of 5 parts of 2-hydroxy-2methylpropiophenone mixed with 500 parts of methyl ethyl ketone was uniformly coated on a commonly available printing blanket by a spin coating method, and heated at 90°C for 20 minutes to remove the solvent. was vaporized. The coating thickness was 12μ. This was irradiated with light for 20 seconds from a distance of 12 boxes using a high-pressure mercury lamp manufactured by Hanovia, Inc. in the United States with an output of 80 w/m'' to obtain a surface-treated blanket.

Example 4 100 parts of the resin solution obtained in Example 3, 07 parts of azobisisobutyronitrile, and 50 parts of methyl ethyl ketone
0 parts of the solution was spin-coated onto an offset printing blanket and left at room temperature for 24 hours to volatilize the solvent. The coating thickness was 10μ. This was heated in the open at 100° C. for 2 hours to cure and obtain a surface treated blanket.

Example 5 A solution obtained by mixing 100 parts of the resin solution ■ obtained in Example 6 with 7,500 parts of methyl ethyl keto was uniformly coated on a commercially available offset printing blanket by a spin coating method, and heated at 90°C for 20 minutes. The solvent was evaporated by heating for 1 minute.

The coating thickness was 14μ. This is done using a transformer electron accelerator with an electron beam energy of 30'Ok and an electron beam current of 45mA.
A surface-treated blanket was obtained by irradiating with an electron beam of 10 Mrad.

The surface-treated blankets obtained in the Examples and the untreated blankets used as Comparative Examples were attached to an offset printing machine (Faboritsu) RF-01 manufactured by Mann-Roland, West Germany, and offset printing was performed as usual. The ink is New Champion Super A manufactured by Dainippon Ink & Chemicals.
PEx Beni was used.

The results of this printing 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 25- (3) Reproduction of halftone dots in coated paper (4) Reproducibility of halftone dots on high-quality paper (outline of halftone dots, reproducibility of pixels) (5) Piling of ink on blanket (piling state of ink)

Claims (1)

[Scope of Claims] 1. (A) A linear polyester containing hydroxyl groups at both terminals, (
The main component is an unsaturated urethane resin obtained by reacting B) a polyisocyanate compound, (C) a 1lf4 polymerizable unsaturated compound having an active hydrogen atom that can react with an isocyanate group, and a polyhydric alcohol. A resin composition for surface treatment of printing blankets containing as follows. 2 The content concentration of the cyclic structure contained in the molecule of the unsaturated urethane resin is 0.5X10 to 3 to 3.0X10-s mol/
The composition according to claim 1, wherein g. 3. The concentration of addition polymerizable unsaturated bonds contained in the molecules of the unsaturated urethane resin is 0.5X10-" to 2.0X1.
1] -3 mol/g The composition according to claim 1 4 The unsaturated urethane resin has an ether bond content concentration in the molecule of O to 1.4X10-' mol/g. The composition according to item 1. 5. The number average molecular weight of the linear polyester containing hydroxyl groups at both ends is 500 to 4000, and the number average molecular weight of the unsaturated polyester urethane resin obtained using the same is 4000 to 1.
7000. The composition according to claim 1.