DE2358948A1 - UV-CURING INKS - Google Patents

Description

UV curing inks have been out of print for some time Patent literature known. Only recently, however, have UV printing inks been developed that have a certain degree of practical maturity. However, all of the UV printing ink systems known to date still adhere to a number of different, sometimes more severe, systems Lack of, so that they are not yet on the market were able to enforce. -, "

UV printing inks: have the same properties as conventional printing inks some potential benefits; they can be completely solvent-free being constructed; they are essential in web printing, for example more environmentally friendly than conventional heat-set printing inks, in which sometimes considerable amounts of unburned or partially burned Mineral oils are emitted into the atmosphere; in sheetfed printing, especially in the production of higher quality Reversing color prints or when printing on little or not absorbent substrates, such as specially coated papers, metal or plastic foils, is the processing speed oxidative because of the slow drying rates drying systems are often so low that "front pressure up to Further processing, such as cutting, folding, etc., takes up to 10 hours and more pass, making productivity low The efficiency of the expensive printing machines is not being used to full capacity and high storage costs arise. With the UV curing Printing ink, on the other hand, can dry immediately after leaving the printed sheet can be reached from the printing unit on any printing material without depositing in the stack or needs to be pollinated. .

UV printing inks. Have compared to conventional printing inks there are also some technical printing advantages, which improve the quality der'prints concerns. It can be s.B. higher abrasion resistance

196/73 - 2 -

509822/0829

of the finished prints. By the possibility of bein Being able to dry or dry on multicolor printing quickly after each individual application of color becomes the quality-reducing printing phenomenon "Doubling" completely prevented. The difficult and often lengthy exact coordination of the color sequence with viscosity and Tack gradations of wet-on-wet printing, especially in letterpress printing, are achieved by drying each individual color before the next Paint application, made much easier and problem-free.

In order to actually achieve all of these potential advantages of UV printing inks over conventional printing inks, one must UV printing inks meet the following four main requirements.

1. Curing speed :

An extremely high curing activity under UV light is necessary with the lowest possible number of high-performance UV lamps, e.g. a high-pressure mercury lamp with a spec. power of 80 watts per cm sheet length and per application of paint. The economy the process depends heavily on the investment costs of the UV drying system and its energy and maintenance costs for drying. With offset web printing, the investment costs are compared to a UV drying system conventional heat-set heat drying systems considerably less. However, ongoing operating costs can be significant with UV curing higher if too high a lamp output has to be installed due to insufficient curing activity of the UV ink. In sheetfed printing there are investment costs and operating costs Case of paper printing, new addition. These costs have to go with the cost savings due to higher productivity when printing with UV inks compete.

2. Printability :

The printing properties of the UV printing inks with regard to Viscosity, tack, viscosity and tack behavior when the temperature changes and print speed change., especially the printability at very high print speeds, im Offset printing, in addition, behavior against water, must be the stand

509822/0829

correspond to the technology of conventional printing inks. To a To achieve very "fast UV curing, UV printing inks have to have a completely different structure than conventional printing inks." In order to use completely differently structured printing ink binders the To meet the requirements described here, i.e. print UV inks just as easily at high printing speeds To be able to work like good conventional printing inks, it is not enough to use a binder from rapidly polymerizing, in the patent literature under "crosslinking monomers" or "photopolymerizable Monomers "frequently mentioned substances. Selection and combination of the individual components of the binder for UV inks do not just have to be high in terms of Curing speed, but especially in terms of be done very carefully to ensure optimal printability.

3. Toxicity, skin irritation, aggressiveness to printing machine and printing material: -

In order to enable very rapid UV curing, connecting parts must be used when building up the photopolymerizable compounds installed, which are more or less toxic, as well as skin- and irritate the mucous membranes, as well as dissolving or swelling on roller covers in the printing press and on coatings of Pressure plates can act. Those involved in the build-up of the binder Components must therefore be in their chemical structure and in their physical properties must be such that the negative effects of the rapidly polymerizing connecting parts be kept as low as possible or eliminated.

i ». Storage stability. : ·

The printing inks should have the highest possible storage stability of have at least 3 to 6 months. The storage stability under Exclusion of light depends essentially on the stability of the monomers used and the thermal stability of the used Photoinitiator.

509822/0829

If the sensitivity is not too great, the stability of the monomers can be increased by adding conventional polymerization inhibitors regulate relatively easily. A large number of the particularly effective photoinitiators generally known to the person skilled in the art However, even in the dark it supplies radicals which dissolve polymerizatio'nsaus, which can also be prevented by larger amounts of inhibitors Impairment of photopolymerization can no longer be intercepted. The photoinitiator to be used must therefore be special must be carefully selected for very fast drying, also with regard to storage stability.

A hardening of printing inks is known from GDR-PS 5 * 1 705 to achieve by UV irradiation in that a binder of conventional structure, only with the use of wood oils, low Quantities of a sulfur-containing photoinitiator are added. The disadvantage of this process, however, is that the Photocrosslinking of the double bonds of the unsaturated resin and oleic acid derivatives is still too slow. The achievable with this Drying times of at least approx. 0.5 - 1 second. under the conditions described are not sufficient to cope with the drying times of conventional heat-set or quick-set Printing inks to compete under economic conditions, the printing inks also show insufficient stability the press, i.e. they dry by air hardening in the printing machine which is very undesirable, especially when the machine is at a standstill is. In addition, these colors also have an unpleasant odor.

These disadvantages also apply in part to binders with a similar structure, which are described in DT-OS 1 79 ¹ I 230. In DT-OS 1 .. '694 930 and in US Pat. No. 3,551,216, printing inks are described which are in part free from fatty oils and mineral oils. In these printing inks, multifunctional acrylates of simple poly oils, such as trimethylolpropane triacrylate, are used in addition to resins and photoinitiators. The disadvantage here is the high toxicity and skin-irritating effect of the acrylic acid esters used, especially when the vapors or aerosols are inhaled, and because they are hepatotoxic

509822/0829 " ⁵ "

Effect particularly dubious use of chlorinated -Bi-. and triphenylene. Another disadvantage is the still insufficient curing speed with minimum exposure times of over 1 second. Those printing inks in the above-mentioned patents which do not contain chlorinated aromatics are less toxic, but are still very irritating to the skin. Furthermore, they only have a storage stability of a few days to 2 weeks at best Tack increase above "the values of conventional inks at" high printing speeds, which severely limits the production speed ^.: \\

DT-OS 2 200 478 describes printing inks in which fatty oils and acrylic ester groups are contained together in the photopolymerizable molecules. Although these printing inks have good printability with low toxicity, the minimum exposure times that can be achieved are far from sufficient for economic use. _:

In the examples given, with significantly better drying activity no or significantly less oils are used and, instead, as reactive diluents, polyfunctional acrylic acid esters of simple polyols such as trimethylolpropane triacrylate or Pentaerythritol tetraacrylate used. The disadvantage here is again the high toxicity and above all the highly irritating to the skin Effect of the specified acrylic acid esters. Another disadvantage. is the severe deterioration in the, now insufficient, printability compared to the oil-containing combinations.

DT-OS 2,157,115 and 2,153,529 also mention combinations of fatty oils with (meth) acrylic acid esters as photopolymerizable constituents. By adding high proportions of fatty oils, mineral oils and other printing auxiliaries necessary for printability, good printability with low toxicity is achieved, but the necessary exposure times of 1 to 2 seconds are one factor for economical use of these printing inks 5 to 10 too high.

^:::. ■ '. : - ^: - β 09822/0029 ^

■ - 6 -

The examples of UV-curing printing inks discussed here in the patent literature that has become known show that it has not yet been possible to develop a practical and at the same time economical UV printing ink which at the same time fulfills all four main requirements to a high degree. For this reason, UV printing inks have not yet been able to establish themselves on the market and are only used to a small extent in a few special applications.

The object of the present invention is to provide an extremely rapid curing under the influence of ultraviolet light, with conventional Pigments, photopolymerizing binder and printing inks made from them for letterpress and offset printing to show which uses essentially little or no fatty oils and hard resins of conventional binders and an exposure time of less than 0.2 seconds. when irradiated with high-pressure mercury lamps and in layer thicknesses of 0.8 to 1.5 / U, needed.

Another object of the invention is to provide photopolymerizable To show systems and printing inks produced from them, many a very good printability of the printing inks at high printing speeds allow.

Another object of the invention is to achieve the required short exposure times, among other things

1. by means of a special, synergistic combination of monomers and photoinitiators, which are much less sensitive to inhibition during photopolymerization by atmospheric oxygen, and

2. to achieve that no or only insignificant amounts of plasticizing oil-containing compounds or fats or oils Mineral oils are used in the printing ink.

- 6a -

509 8 2 2/0829

7353948

Another task d / er invention is the individual photopolymerizable Compounds to be counted in such a way that each individual substance has the lowest possible toxicity, skin and Mucous membranes on direct contact, but especially over Vapors and aerosols not or at most after long exposure

509822/0829

? 3S8948 - τ -

duration in particularly sensitive people in the case of worse or no protective measures when using, mildly irritating and also does not penetrate the skin on contact with the development of toxic effects. The connections should be very special be selected so that there is no risk of inhalation toxicity consists.

Another object of the invention is to show printing ink components or printing inks which roller covers are used in the printing machines as well as printing form material do not attack or swell in a disruptive manner.

The present invention relates to printing inks which cure under the influence of UV rays and which are characterized are that they consist essentially of

(A) 0 to 30 percent by weight of a conventional printing ink

Pigments,

(B) 0.5 to 15 "of a mixture roughly the same

Amounts of benzophenone and Michlers' ketone,

(C) 25 to 90 "of at least one of fatty acid residues with more than β carbon atoms free olefinically unsaturated compound of the acrylic type, which contains at least one urethane group per molecule and has a molecular weight of 250 to 4000, preferably a mixture of a higher molecular weight component CI with a molecular weight of 800 to 4000, preferably 1000 2000 and a low molecular weight component CII with a molecular weight of 250-800, preferably 350-600 is used ₉ and

(D) 5 to 35 "at least one compound that

the grouping CH ₀ = CR-CJ where

509822/0 8 29

and or ;

(E) 5 to 35 weight percent;

R stands for hydrogen or a methyl group, contains at least once ^ preferably 2 to 3 real per molecule, has a vapor pressure of / of / less than 1 Torr ^{at IQO 0} C and is liquid ^{at 50 0 C}

at least one compound which has the grouping CH ₀ = CR-C-NH-CH ₀ -O-,

where R stands for hydrogen or a methyl group, is bonded to a branched alkyl or cycloalkyl radical with up to 12 carbon atoms, at least once, preferably 2 to 3 times per molecule, has a vapor pressure of less than 1 Torr at 100.degree 5O ⁰ C is liquid,

wherein the mixture of (CII) + (D) and / or (E) has a viscosity of more than 1 poise, preferably 20 to 80 poise (at 30 C), with the proviso that the sum of the under (A) to ( E) mentioned percentages is 100. _:

The printing inks according to the invention provide the abovementioned Tasks fulfilled to a high degree. - ■ - ■

Those UV-curing printing inks according to the invention are preferred which. . ' - ^{:. :} -. ■. ■ · .'- ■ ■; .'-. · · "_; . / 0 or 14-20 percent by weight of component (A),

2-10 "V

10-40 "30-60 ..". ■ ". .10-25""and / or 10-25 [["'"

included, with the proviso that the sum of the under (A) - (E), mentioned percentages is 100.

503822/0829 /

Ii Il (B), H 1! (CX), » I! (CII), ti Il (D) ,,

Those according to the invention are also particularly preferred UV-curing printing inks, the component (CI) of which is 3 to 6 polymerizable contains acrylic type olefinic double bonds and 2 to 6 urethane groups per molecule.

Such UV-curing printing inks have also proven to be particularly advantageous proved the as component (D) reaction products of diglycidyl ethers branched aliphatic or cycloaliphatic Contain diols with at least 1 mole of acrylic acid / epoxy group.

The bis-K-methylolacrylamide ethers have also been found to be component (E) of neopentyl glycol or neopentyl glycol monoester proved to be particularly advantageous in the UY-curing printing inks according to the invention.

Surprisingly, it has been found that the components (C) urethane acrylates described in more detail below, which are composed of aliphatic or cycloaliphatic di- or polyisocyanates and hydroxyl-containing acrylic acid esters or N-methylolacrylamide ethers have been produced, when used as the main components, a very good printability of the printing inks Allow high printing speeds customary in practice without oily constituents being necessary and in the system according to the invention at the same time also meet all other conditions mentioned above.

It is known that the free-radical polymerization, in particular also photopolymerization, of acrylic compounds is slowed down very sharply by atmospheric oxygen or can even be completely prevented. This influence of atmospheric oxygen is particularly noticeable in the thin layers of printing ink, which are only about 0.8 to 1.5 / U thick (e.g. in paper printing per color application). It has now been found, surprisingly, that the inhibiting influence of atmospheric oxygen on the rate of polymerization of acrylic double bonds is particularly low ₃ if a mixture of Michler's ketone and benzophenone is used as the photoinitiator and the acrylic compounds are simultaneously in the form of urethane.

- 10 -

509822/0829

. ■■■ - ■ - ■ .- ίθ - - - ■. ■■: - ■ - ■

acry! compounds (C) are present. The particularly low sensitivity to oxygen the inventive combination compared to others Monomer / initiator combinations are shown in a comparative example.

Build-up to the UV-curing printing inks according to the invention Components are to be executed in detail as follows:

(A) All pigments used in printing inks can be used as pigments are usually used and which are described, for example, in the Color Inex, if they are not are incompatible in the binder. Are particularly suitable all pigments that are as low as possible in the near UV spectrum Own absorption.

(B) According to the invention, mixtures of are used as photoinitiators Benzophenone and Michlers' ketone used. Of the mixtures of Michler's ketone and benzophenone, those in a weight ratio of 1:10 to 10: 1 are possible, preferably those in Weight ratio 1: 1. The effectiveness of this initiator combination generally depends to a very large extent on the nature of the binder components, as these are involved in the formation the radicals that trigger the polymerization are involved. the Photopolymerization can use unsaturated polyesters or alkyd resins or numerous aromatic compounds even strongly inhibit or completely prevent. In the inventive

■ appropriate printing ink mixtures shows this initiator combination a particularly high initiator activity (see Comparative Example I). In combination with the main components according to the invention of the binder, the oxygen sensitivity of the curing reaction is particularly low. 0.5 to 15, preferably 2 to 10 percent by weight of component (B) are used in the printing ink system according to the invention.

(C) As component (C) with an average molar weight between 250 and 4000, preferably 350 to 2000, and at least one polymerizable olefinically unsaturated double bond, preferably of the (meth) acrylic type CH ₂ = CR-C- and at least

O'

509822/0829

one preferably 2 to 6 urethane groupings come e.g. in question:

From a) bifunctional or trifunctional primary or primary / secondary amines and b) bifunctional isocyanates, polyfunctional isocyanates containing biuret and / or urea groups, which are reacted with c) equivalent amounts of hydroxyl-containing (meth) acrylic acid esters or N-methylolacrylamide ethers to form "urethane acrylic compounds" have been,
or and

urethane group-containing di-, tri- or urethane groups produced from a ') di-, tri- or tetraols and b) bifunctional isocyanates tetrafunctional isocyanates, which with c) equivalent amounts of hydroxyl-containing (meth) acrylic acid esters or N-methylolacrylamide ethers converted to "urethane acrylic compounds" have been.

Suitable amines a) are straight-chain and branched aliphatic or cycloaliphatic diamines of the general formula KpN-R-NEp, where R is an aliphatic or cycloaliphatic hydrocarbon radical with 1 to 20 carbon atoms, which can optionally also have a CO, NH or NEL group , is, such as ethylenediamine, 1,2-propylenediamine, 1,3-diaminopropane, dipropylenetriamine, hexamethylenediamine, 2-aminomethylcyclopentylamine, 4,4'-diaminocyciohexylmethane, 3,3 ^f -dimethyl, 4,4 'diaminodicyclohexylmethane, 2,2 -Bis- (4-aminocyclohexyl) propane and others.

Suitable di-, tri- or tetraols a ¹ ) are simple polyfunctional alcohols such as diols with 2-8 carbon atoms, * ri_e e.g. ethylene glycol, propanediols, butanediols, pentanediols, hexanediols, triols such as glycerol, trimethylolpropane, hexanediols .. pentaerythritol, etc. or the polyether polyols produced therefrom, which are obtained by reacting 1 molecule of alcohol with 1-10 molecules of ethylene oxide or propylene oxide.

Suitable bifunctional isocyanates b) are aliphatic or cycloaliphatic isocyanates of the general formula

- 12 -

509822/0829

OCN-RrNCO, where R stands for a hydrocarbon radical with 4 to 15 carbon atoms. Examples of such diisocyanates are: hexamethylene diisocyanate, isophorone diisocyanate, bis- (-4-isocyanato-cy.clohexyD-methane, bis- (3-tt ¹ -ethyl-J | -isocyanatocyclohexyl) methane or 2,2-bis- (4 -isocyanato-cyclohexyl) propane. ■

As (meth) acrylic compounds containing hydroxyl groups c) are Partial esters of polyhydric alcohols with (i-Teth) acrylic acid, such as e.g. ethylene glycol monoimethacrylate, 1,2- 'or 1,3-propanediol mono (meth) acrylate, !, iJ-ButandiolmonoCmethXacrylat, 1,6-Hexanediolmono (meth) acrylate, TrimethylolpropandiacrylEt, glycerol diacrylate, Pentaerythritol triacrylate as well as the mono (N-methylol- (meth) acrylamide) ethers of ethylene glycol, propylene glycol, Butanediol, hexanediol, neopentyl glycol are suitable. -,

Particularly preferred compounds CI are the reaction products of biuret isocyanates, which are derived from hexamethylene diisocyanate have been made, with Hydroxypropylacryla.t, as well Urethane isocyanates ,. which are built up from 1 mole or trimethylolpropane a polyether polyol made from 1 mole of trimethylol propane + 3-5 moles of propylene oxide, with 3 "moles Hexamethylene diisocyanate and 3 moles of hydroxypropyl acrylate.

Furthermore, the reaction products are particularly preferred as compounds CI of the above-mentioned cycloaliphatic diisocyanates with trimethylolpropane diacrylate or pentaerythritol triacrylate .

Particularly preferred compounds CII are the reaction products of hexamethylene diisocyanate with ethylene glycol monoacrylate, propanediol monoacrylate, butanediol monoacrylate, trimethyloipropanediacrylate or pentaerythritol triaerylate. Component (C) is used in an amount of 25 to 90 , preferably MO to 85 percent by weight in the printing ink according to the invention.

(D) As compounds which have the grouping CH ₅ = CR-Ct ,. where R

Is hydrogen or a methyl group, -m.inffe-st.ens once ^per: containing molecule, those are suitable that at 100 ⁰ C a

B09822 / 0829: ■ " ¹³ "

Vapor pressure of less than 1 Torr at '•' ei? «Η, at 50 ⁰ C fl'isr; - · r, and produce polymers which are hard or tough at room temperature.

As the component (D) are for example particularly suitable * ^r onnectivity of the general formula

CH ₀ = CR ₁ -CO-CH ₀ -CH-CH ₀ -OR ₀ -O-CH ₀ -CH-CH ₀ -OC-Cr ₁ CCH ₀

0 OR, OR ₁ . 0

in which R. is hydrogen or a methyl or cyano group and R _{2 is} a hydrocarbon radical with 1 to 8 carbon atoms, and R, and R ^ are identical or different from one another and are hydrogen, an alkyl radical with 1 - H carbon atoms or an optionally unsaturated acyl radical with 1-5 carbon atoms which, for example, have been prepared by reacting diglycidyl ethers of aliphatic diols or polyols, such as ethylene glycol, propanediol, butanediol, kexanediol, di * ithylenp; glycol, triethylene glycol with at least one mole per epoxy group as long as they have ^{a vapor pressure of less than 1 torr at 100 °} C. Component (D) is contained in the printing ink according to the invention in a range of 5-35, preferably 10-25, percent by weight.

(E) As component (E), which can be used instead of component (D) or in addition to component (D) are preferably suitable the bis-M-F-ethylolacrylamid.nther of Neopentyl glycol, kydroxypivalins, muremono-ethylene glycol ester, -propanediol monoester, -butanediol monoester, -hexanediol monoester and neopentyl glycol monoesters or of divalent alkylene-substituted ones cycloaliphatic diols, such as cyclohexanediol or cyclopentanediol derivatives.

Components (CII) to (E) should be compatible with components (E) and (CI); they are ^{liquid at 50 °} C., but generally also at room temperature, and have a vapor pressure of less than 1 Torr at 100 ^° C. , and a viscosity of about 1 poise ₃ preferably 20 to 80 poise (at 3O ⁰ C), and act as reactive diluents to adjust the viscosity and tack of the ink for the respective desired application. Compared to the reactive thinners already known for printing inks such as Kthvlenglykoldiacrylat, di- or triethylene glycol diacrylate, butanediol

BAD ORfGiMAL °

diacrylate ,. Trimethylolpropane triacrylate, hydroxyethyl erylate. Hydroxypropyl acrylate, hydroxybutyl acrylate, benzyl acrylate and other, simply structured acrylic acid esters have the reactive components (CII) to (E) for use in printing inks, the following advantages: An unpleasant odor and danger the inhalation toxicity no longer exists, the lifespan of the Rubber coverings from printing rollers are hardly affected negatively. Their toxicity and skin irritation effects as well as those along with (A) to (CI) printing inks made from it is opposite such printing inks, which contain acrylates, among others, are essential decreased.

509 822/08 29 BADORK ₃₁ NAL

In the preparation of components (C), (D) and (E) according to per se known processes for the reaction of isocyanates or Epoxidsn with alcohols or the etherification of N-methylolacrylamide with primary alcohols, not only pure compounds are formed, but also mixtures of isomers and compounds of partially and fully implemented products in the case of polyfunctional ones Links. These by-products do not have to be disadvantageous, but can have an adverse effect on the properties of the overall composition impact. The stated numbers of moles therefore only represent a description of the idealized structures in the inventive Mixtures of substances used. In some cases it is necessary, e.g. in the production of isocyanates of component (C) or, in the preparation of component (E), more than the amount of diisocyanate or N-methylolacrylamide to be reacted to use. Unreacted compounds, insofar as they have a disruptive effect, are removed after the reaction has ended by distillation or Removed deodorization in vacuo or by washing or other common cleaning methods. This also happens with odorous and / or toxic substances, e.g. xtfie Acrylic acid and low-boiling acrylic acid esters, interfering catalysts, etc. After the polyisocyanates have reacted with hydroxyalkyl acrylates are not allowed to use free isocyanate groups and if possible, no more free hydroxyalkyl acrylate should be present either. Small residues of isocyanate are grounded by adding 1-3 $ ' Alcohols such as methanol, ethanol reacted.

To modify the printability properties or properties of the cured prints produced therewith, the printing inks according to the invention can be used in small amounts, as far as compatible, still hard resins or polymerizing soft resins, other monomers which are oil-free or oil-containing, as well as common practice Printing auxiliaries can be added to a limited extent. However, care must be taken that the properties of the printing inks according to the invention are not adversely affected.

The parts and percentages given in the examples and comparative examples relate to, unless stated otherwise the weight.

509822/08 2 9

Comparative example I · ■

Various monomers were each mixed with A percent by weight photoinitiator or mixtures thereof, with stirring and heating to 60 Cj. Of the mixtures, 6 u thick films were applied to art paper by means of a doctor blade. Half of the liquid film layer was covered with a thin, transparent, air-impermeable plastic film which, after exposure, shows little or no adhesion to the monomers or polymers used. With the exception of the already dissolved atmospheric oxygen, the film no longer comes into contact with atmospheric oxygen during the subsequent exposure at the covered area. The liquid films were exposed by means of a flat exposure unit: / Ideal from Moll, Solingen, which was equipped with 20 pieces * ίθ Watt low-pressure fluorescent tubes. The exposure time after which the film was completely tack-free was determined. In many cases, the time before the film was completely tack-free was preceded by a long time, during which the film no longer deposited (when it came into contact with a counter paper) and was only slightly tacky. The beginning of this time is given as the lower limit. The following monomers were used:

I As a representative of simple crosslinking acrylic acid esters the trimethylolpropane triacrylate (abbreviation TMPTA),

II as a representative of (E) the N-Methylolacr'ylamidäther the Neopentyl glycol bis (N-methylolacrylamide) ether, (abbreviation NA),

III as a representative of the "urethanecry! Compounds" (C)

the reaction product of diisocyanate with a mixture of isomers _{Hexamethylendiiso%%} \ 1 of, ^ - l-Propändiol monoacrylate and l, 2-propanediol-2-monoacr ^ lat (= hydroxypropyl) Abbreviation HMDI / 2 HPA).

Because of the low viscosity of trimethylolpropane triacrylate, which would falsify the results in the direction of longer exposure times, the trimethylolpropane triacrylate was manufactured ^{with a compatible resin, here v 'Santolite MHP}

•. - 16 -

RfI 9 8 7? / Π8 2 9

Monsanto, mixed: This also has the advantage that jev / eils only mixtures with similar double bond concentrations are compared. The photoinitiators have been abbreviated as follows

BPA = benzoin isopropyl ether

BPh = benzophenone M.K. = MichfWler's ketone

No. Composition parts by weight

Exposure time (sec) Factor of the with foil without foil Oo-Err.pfind-

opportunity

1 61 TMPTA, 35
MHP, 4 BPA 4 BPh N / A HMDI / 2KPA Santolite dd + 2BPA 4BPA 3 I8OO-I9OO 640 2 ti 4 MK dd ti H- 2MK 2BPh +
2BPA 180-300 5400 3 Il
ti 2 BPh + ti It
2 BPA Santolite TffiP 2BPh +
2MK 6th 240.0 400 4th Il
II 2 BPh + It
2 MK 2BPh + 2 1800 900 5 II
ti 4 BPA , 5TM 1 420-600 600 6th 96 HMDI / 2HPA 4 BPh 2-3 600 200-300 7th ti 4 MK 10-12 3600 8th Il ER / 3HMDI / 4HPA 180 3600 9 Il 2 IIOO-I5OO 750 10 ti 1 240-500 500 11 96 TMPTA, 35 2 ■ 900 450 12th ! I 5TÄA, 4BPA 5 1800-2000 400 13th dd 91 3 1800 600 14th ti 91 2 1200-1500 750 15th Il 91 2BPh + 2BPA 1 10-15 15th 16 56 96 2BPh + 2MK 1 ■ 420 420 4BPA 17th 4BPh 2 1000-1200 600 18th 4MK 2 900-1200 600 19th • 2BPh 1 6-8 sec 8th 20th 2BPh 2MK H " 60 " 15th

- 17 -

R η a 8 9 71 ü 8 2 9

/ 96 Desmodur Ν / 3.3 ΗΡΑ 2BPH + .2M.K. 8 "30" 4

-22 96 Polyatherpolyöl / JiHrI

■ 5HPA ■■ ".: ■ 2.BPh + 2Μ.Κ. 3 ^t: 60-90" 20-30 "

23 9'6 TDI / 2HPA. 2EPh + 2Μ.Κ. 60-90 "3600 40-60

24 $ 6 HMD I / 2HPA 2BPh. + Ν

-. ■■■ 2 methane base 4 "3600 900

_{Abbreviations:::}

HMDI: hexamethylene diisocyanate

TDI: toluene diisocyanate

HPA: hydroxypropyl aerylate

TÄA: triethanolamine

Methane base: 4,4'-dimethylaminodiphenol methane

ÄH / 3HMDI / 4HPA = urethane acrylate mixture from 1 mol of ethylene urea . "■■" + 2 moles of HMDI to new diisocyanate and excess HMDI implemented. All isocyanate groups - fully implemented with a total of 4 moles of HPA.

^(R) Desmodur H / 3.3HPA. similar to ÄH / 3HKDI / 4HPA constructed polyether polyol / 4HMDI / 5HPA

Desmodur N = multifunction. Isocyanate, manufacturer of inking units

Bayer AG "- ■ '■ ^.-": "". "

Polyether polyol: Manufactured by converting 1 mol of TrI- ■ methylolpropane with 4.2 moles of propylene oxide.

The comparison of the .Mixtures 11-14 with 1-10 shows that the Urethane acrylates (C) just as sensitive to oxygen as others *, Acry! Compounds are. Misehings 5, 10, 15 prove that known synergistic effect of the photoinitiator combination benzophenone + Michler's ketone. Mixes 5 and 10 show further that this initiation or combination with the simple Acrylic acid esters or one with the N-methylolacrylamide ethers about the same, have great sensitivity to oxygen, like this one Monomers with different photo initiation,

For the combination of the urethane acrylate with Michler's ketone / Benzophenone should therefore have an exposure time according to the state of the art in the presence of atmospheric oxygen from approx. 400-600 sec-be expected. However, only one exposure

09 8 22/08 29

_ Λ D

- Λ fl -

time of 10 - 15 sec. The exposure time at Ferrrtialtuns of Air oxygen, on the other hand, is within the expected range. The low atmospheric oxygen dependence of the photopolymerization of these special combination of urethane acrylic compound (C) and photoinitiator mixture is surprising and has not yet been described. This effect is not only for printing inks but also for the photopolymerization of other thin layers, such as coating materials for negative offset printing plates as well as for photoresist.

The synergistic effect with regard to the significantly lower oxygen sensitivity is when combined with other components (C) See Comparative Examples 20-22 to be observed to a similar extent. Similar results as with trimethylolpropane triacrylate is also obtained with other simple polyacrylates or with the acrylates described under (D).

Urethane acrylates, polyglot made from aromatic isocyanates are, as Example 23 shows, used in larger amounts, unsuitable.

In US Pat. No. 3,552,986 it was suggested to limit the sensitivity to oxygen among other things by adding regulators such as amines to the photo-polymerizable mixture. Comparative Examples Nos. 16 to 19 show that, however only leads to a significantly smaller improvement than with the synergistic monomer / initiator combination according to the invention. Comparative example 24 proves in addition to example 13j that the greatly reduced sensitivity to oxygen is also not partly caused by the property of Michler's ketone as an amine, but only by the photoinitiator property of Michler's ketone, since the aromatic amine analogous to Michler's ketone is completely ineffective without a keto group. The addition of amines is only useful in larger amounts for a good effect and leads due to the physical and / or physiological properties of the amines lead to disadvantages in use. The particularly effective ethanolamines, such as e.g. Triethanolamine are suitable for use because of their water solubility less suitable in offset printing inks.

- 19 509822/0829

When exposed with: Hg-Hochdrueklanipen ur: d R & flectors vrerden oie Exposure times at 'a lair.pen power of: 80 V.'att / cn Arc length by an average factor of 80 each decreased to 120., "" .- - -

Comparative _{Example II ;;} - ..

A series of soft rubber ^ samples of Shore hardness A of approx. 40-60, with a defined length and weight, would be ^{stored in various monomers for 3 days at 25 °} C., after which the samples were carefully freed from externally adhering monomers and the percentage change in length 4.1. as well as weight change ^ .G determines: \ ^; ■■. """"".".ν.; _ ■ ""

Rubber type iGDÄ NA BDGL / ÄS HMDI72HPA. ". + GL / AS 3

Al AG Al & G Al AG Al AG

Natural rubber +3.2 _+2.1; Q: -0.7 0 -0.02 O : '■. "' _ ^. -0.76

Nitrile, ^": - ■

Grade A - +10.6 +27.2 O +0.9 CT +1.2 +0.5 +2.0

^Perbunan; '. ^;

Grade B +8.7 +22.1; + 0, l +0.5 + 0.2 ^ +0.4 +1.4 +1.9

Perbunan, /.- "*" -. "" Y. "

Grade C '+3.5 + 6.5 + 0.5-0.6-0.8 -3.0Y'O; -0.03

Perbunan,. YY _;

Grade D +0.5 +4.8 + 1.2 + 0.3 0 -0.9 0 -0.21

Buna +1.3 +1.8 + .0.9 + 0.7-0.2 -1.2 0 -0.15

Styrene; / \ ... "; Y

Butadiene K. +0.3 +3.6 +0.3 +0.6 +0.3 -0.5 +0.26 Y-0.15 -

Butyl rubber + 0, Q +0.1 OO + 0.3-0.1 0 +0.05

rubber +1.0 +1.6 +0.3 -0.2Y 0-0.5 + 1.3 +0.4

Abbreviations: ÄGDÄ = Xthylenglykoläiäiäerylat

NA = Neopentyl ^ lykQl-bls - (! I-Methylolacrylanid) -äther Y BDGL / AS = Butariäiöldiglyeidylätherdiacrylat. . - HMDI / 2HPA = conversion product _; of 1 ha of hexane ethylene

diisocyanate with 2 moles of hydroxypropyl-Y . acrylates

Rnqftrr / nft? 9 BADORlGiNAL ■ -. 20 - ■ "

Trimethylolpropane triacrylate shows similar, on average somewhat lower values, from ethylene glycol diacrylate. The Terglei ch from ÄGDA with those used in the printing inks according to the invention Monomers shows that ItODA swells rubber in general much more than the other monomers. This is true especially for Perbunan rubbers, which are commonly used in general in printing machines. The Perbunan varieties C and D are used in practice in printing machines.

Examples of printing inks:

In the examples described below, the preferred components used are:

1. A urethane acrylate obtained by reacting the commercially available Biuretisocyanats Desmodur N (manufactured by Farbwerke BAYER, isocyanate content 16.5% ₃ 75 percent solution) ahdestilliert with an equivalent? "Close hydroxypropyl acrylate. After the reaction, the solvent disturbing vairde at 80 ⁰ C in vacuo .

2. Urethane acrylate B, obtained by

a) reacting 1 mole of 3,3'-Dimethy1-4,4'-diaminodicyelohexyl- • methane with 8! V ol hexamethylene! (F '* DI) to ols to a conversion of about 4.7 ^T H f ! * DI or an isocyanate content of approx. 30 to 31 % and

b) reaction with an equivalent amount of hydroxylpropyl acrylate. After the reaction had ended, deodorization was carried out briefly in a vacuum. The product contains both a component (CI) and a component (CII).

3. Urethane acrylate (C), obtained by reacting a poly ^ therpolyol from 1? iol trimethylolpropane and 4 mol propylene oxide with 3 moles of HMDI and 3 moles of HPA.

4. Urethane acrylate (D) obtained by reacting 1 ^M ol bis- (3) -methyl-4-isocyanato-cyclohexyl) -methane with 2 Koi Trimethylolpropandxacrylat.

- 21 - BAD OBtGINAL KnQft9? / 08 2 9

5 '.. urethane acrylate (E), obtained by reacting 1 mol of HMDI with 2 moles of HPA, briefly deodorized in a vacuum.

6. Urethane acrylate (P), obtained by reacting 1 mole of bis (3-methyl-4-isoeyanato-cyclohexyl) methane with 2 moles of HPA.

7. a) Bis- (N-methylolacrylamide / neopentyl glycol ether

Abbr. NA, obtained by acidic etherification of 1 mol Neopentyl glycol in the presence of 3 moles of N-methylolacrylamide in toluene solution. Purification by filtration, washing out with water and distilling off the solvent.

b) Analogously to hydroxypivalic acid neopentylglycol bis (N-methylolacrylamide) ether; HPNA. -

8. A diglycidyl ether diacrylate, abbr. BDGL / AS produced by Implementation of a commercially available butanediol glycidyl ether, which even larger amounts of butanediol ether with only one spoxide group contains, epoxy value approx. 0.6-0.7 with 0.96 equivalents Acrylic acid. Deodorized in a vacuum.

The substances listed, which are not claimed here, were produced in accordance with generally known methods

. Gfeirbonsäur-s

the reaction of isocyanates with alcohols, epoxides with & ik or the etherification of alcohols, so that a detailed description is not necessary. ·

Example 1 '

A binder was obtained by homogeneously mixing 30 parts by weight of urethane acrylate A kk "urethane acrylate E 20" N-methylol acrylamide ether HPMA 3. ". Michler's ketone
3 "benzophenone

0.1. "Phenonthiazine ■;

manufactured and 20 $ with the pigments listed below rubbed on the three-roller mill.

509822/0829

WHEEL

Exposure tests: The pure .binder screamed the pi ;;, "'": ierte printing inks were by means of a pressure press in Sch. ... tthicknesses of approx. 1-1.3 / U are printed on standard art paper Apco II / II and the _{exposure time necessary to achieve complete freedom from tack s} as described in Comparative Example I is immediately determined. In addition to the blue pigment, 3 % Michler's ketone + 3 % benzophenone were also rubbed in.

Exposure times

a) unpigmented: 5 see

( R)

b) pigment = ^v permanent yellow GR (manufacturer Farbwerke Hoechst AG

: 7 see

c) "= ^ Litholrubin 4580 (manufacturer BASF AG): 8 see

d) "= ^(R) Heliogen blue 7080 (manufacturer BASF AG): 13 see

When exposed with a high-pressure mercury lamp, 80 watt / cm reflector for illuminating a sheet width of 20-25 cm, distance 10 cm, results in a factor of 90 (unpigmented) to 120 (blue) reduced exposure times. This also applies to the following examples.

Example 2; As described in Example 1), a binding

medium off Urethane acrylate B. manufactured, pigmented 30 parts by weight Urethane acrylate E. Hk HPNA 20 ^I! Michler's ketone 3 Benzophenone 3 Phenothiazine 0.1 and tested.

Exposure times:

a) unpigmented: k see

b) pigment = ^(R) lithol ruby 4580: 7 see

c) "= ^ Heliogen blue 7080: 11 see. with additional initiators as in Example 1.

- 23 BADORKBIMAL 509822/0829

Example 3- : "■ *% * ' ; Λ

A binder would be prepared as described in Example 1) the end :

15 parts by weight of urethane acrylate B

68 "urethane acrylate E ■>

10 "glycidyl ether acrylate BDGL / AS

3.5 "Michler's ketone - ·

3.5 "benzophenone
0.15 "phenothiazine

A printing ink is produced by pigmenting with 18 % heliogen blue. The printing ink has a tack value of 130 at 50 m / min and 270 at 200 m / min, measured on a tack-o-scope from Rudolph Meyer, Amsterdam. The printing ink was printed on a letterpress sheet-fed printing press equipped with a UV hardening device from Pirma Hanovia, containing a}} g high-pressure lamp 80 watts / cm * with a sheet length of 70 cm and a printing speed of 10,000 sheets / hour were obtained on coated paper (12Ό g / m), which were completely non-sagging and, after a short post-curing time, completely wipe-proof. The prints showed good print sharpness with an attractive gloss. The same results were also obtained with lithol yellow or lithol ruby as pigment at 12,000 sheets / hour. There is no odor nuisance during printing and the printing ink is still stable after 3.5 months of storage.

Example 4 '.- ■.

It was described as in Example 1), a binder made forth from 10 percent by weight of urethane acrylate B _; 68 "urethane acrylate E -

5 "". Urethane acrylate P

10 · "BDGL / AS. _. '■;. ■■■' ■■ -. '.

3.5 "Michler's ketone ./

3.5 "benzophenone

0.15 "phenothiazine ^; " .--. ,; '

509822/0829

The binder vjurcls v; ie in P ^ -Example 3b-oschrien ^ n pipmortier *. and printed. Almost pale veins were obtained.

Example 5 ·. · .. · - ■

As described in Example 1), a binder made from ··· - ■ ■ - · - ■ ·. ---'- ...'-. ■ ·: - · ..- ■ '' -.- «■ <- ■" ■■ '■: - -

15 weighted pro ζ ent urethane acrylate B · ..; .;. ·. ·.

k9 ' "· urethane acrylate E · · <■ ·: .x,. <, - :.

20 "NA.. '"' ■■ '

10 "BDGL / AS \.

3 "Michler's Ketone" - ·

3 "benzophenone

0.1 "· phenothiazine

The binder vmrde 16 / iig pigmented with Litholrubin 4580 and printed on the pressure press.

Exposure times for flat exposure units, unpigmented: 5 sec

pigmented: 8 see ;; :

Example 6 '

As described in Example 1), a binder was produced from ■.
15 percent by weight urethane acrylate D

68 ". Urethane Acrylate E-

10 » _% BDGL / AS ■

3.5 "Benzophenone. '.....

3.5 "Michler's ketone

0.1 "· phenothiazine

The binder is 16% pigmented with Lithol Rubin 4580 and printed on an inking offset machine.

Exposure times in the flat exposure unit, unpigmented: 4 seconds

pigmented: 7 see 509822/0829. BADORiGlNAL _a5

Example 7

- ty:

A binder was prepared as described in Example 1 the end: :

30 weight percent urethane acrylate C
53 "urethane acrylate E.
10 "BDGL / ÄS
3.5 "Michler's ketone
3.5 "benzophenone
0.1 "phenothiazine

The binder .wurde was pigmented 16% with Litholrubin 4580 and printed on an offset printing machine from Roland Offenbach, type RZK III. The printing machine was equipped with an ÜV curing device from Pa. Hanovia provided with Hg ~ high pressure lamps 80 watt / cm and ellip. Reflectors. The ink was printed up to a speed of 12,000 sheets / hour without setting off. Only 1 lamp is needed for drying.

- 26th

50 98227 0 8 29

Claims (7)

^: Claim , 1·. Printing ink which cures under the influence of UV rays, characterized in that it consists essentially of (A) O - 30 percent by weight of a conventional printing ink Pigments, (B) 0.5-15 percent by weight of a mixture of Benzophenone and Michler's ketone, (C) 25-90 percent by weight of at least one of fatty acid residues with more than 6 carbon atoms free polymerizable Acrylic type olefinically unsaturated compound containing at least one urethane group per molecule and has an average molecular weight of 250-4000, (D) 5-35 percent by weight of at least one compound which has the grouping CH ₀ = CR-C- wherein R is hydrogen or eine'Methylgruppe containing einmal.pro molecule, at least, at 100 ⁰ C von.weniger has a vapor pressure than 1 Torr, and is liquid at 50 C and / or (E) 5-35 percent by weight of at least one compound which has the grouping CH ₀ = CR-C-NH-CH ₀ -O- wherein R is hydrogen or a methyl group, a branched alkyl radical or cycloalkyl radical having up to 12 carbon atoms, containing at least tied once per molecule, at 100 ⁰ C has a vapor pressure of less than 1 Torr, and is liquid at 5O ⁰ C with with the proviso that the sum of the percentages mentioned under (A) - (E) is 100. - 27 509822/08 29 2. UV-curing printing ink according to claim l _s, characterized in that as component (C) a mixture of a higher molecular weight component (CI) with a molecular weight "· of. 800-4000,. Preferably 1000-2000 and a low molecular weight component ( CII) with a molecular weight of 250-800, preferably 350-600 is used. 3. UV-curing printing ink according to claim 1, characterized in that '. that component (B) is a mixture of approximately equal amounts. Benzophenone and Michler's ketone is. k. UV-curing printing ink according to claim 1 or 2, marked in dädurch - - "j distinguishes that the component (C) 2 - β having polymerizable double bonds of acrylic and / or / Methäcryltyp and 2-6 urethane groups per molecule ·. 5. UV-curing printing ink according to one of the preceding claims, characterized in that component (Cl) has an average molecular weight of 1000-2000. 6. UV-curing printing ink according to one of the preceding claims, dadjar_c ^ _g ^ k ^ iin ^ j ₁ chnet that component (D) and / or (E) the grouping CH ₀ = CR-C- 2-3 times per molecule (ι contains. 7. UV-curing printing ink according to one of the preceding claims, Sayings,; characterized in that the mixture of _y (CII) + ^v (D) or having and / (E) has a viscosity of> 1 poise vorsugsv / else 20 to 80 poise (at 30 ° C). ■ 509 82 2/0 8 29