DE3921459A1 - RADIATION-curable BINDING AGENT SYSTEMS WITH (ALPHA) SUBSTITUTED SULFONYL COMPOUNDS AS PHOTO ACTIVATORS - Google Patents

Abstract

The invention relates to radiation-curable binding agent systems based on radically and/or acid-curable components containing certain alpha-substituted sulphonyl compounds as radical-forming photo-initiators and/or as radiation-activatable latent acid catalysts.

Description

The invention relates to radiation-curable binders systems that use certain α-substituted sulfonyl compounds gene as photo activators included. It is here for binder systems based on radical and / or acid-curable components in which the Invention appropriate photo activators as radical photoinitia toren and / or as radiation-activatable latent acid catalysts act.

A large part of the binder systems in the paint and Coating technology is based on thermosetting materials lien in which cross-linking and so that the curing takes place. For polycondensation The basic materials used here are usually amino plast synthetic resins, the thermal curing of which ren, especially organic sulfonic acids, catalyzed becomes. Typical and very frequently used acid catalyst sator is p-toluenesulfonic acid (PTS). Acid-curable systems have the disadvantage, however, that when used with the acid catalyst are offset, only a limited shelf life possess and will soon gel if they are not internal can be processed in less time. Sulfonic acid catalyst catalysts in "blocked" form, such as amino salts or Oxime esters of hydroxamic acids enable better Storage stability. From these blocked forms, the  catalytically active acids by heating to higher temperatures temperatures are released. The hardening of the correspond the systems hereby require a higher one Energy and time expenditure. Generally the thermal hardness very time-consuming, what for industrial production processes is disadvantageous.

In paint and coating technology, in addition to ther mix curing also photochemically induced curing gained great importance, with special radiation-hardness bare compositions are used, the photo activators or photo initiators to implement the beam energy contained. Radiation curing draws themselves particularly by high speed and low Energy demand. Which gave way for practical application The most radical photopolymerization reaction is the radical one Polyaddition of ethylenic double bonds. Correspond Suitable radiation-curable systems are therefore based on mate rialien, the radically polymerizable or crosslinkable contain ethylenic double bonds and form radicals the photo initiators.

Thermally acid-catalyzed curing systems are in print zip also accessible to radiation curing if instead the usual thermal acid catalysts photochemically activatable latent acid catalysts are used. Due to the effects of radiation, the catalytic must acting acid can be released, which the actual Liche hardening, appropriately promoted by additional supply of thermal energy. For this Purpose Halo-type compounds that have been known for some time gene or sulfonyloxyacetophenones have the disadvantage of kor to look rosy, to yellow the hardened layers or otherwise adversely affect; continue with linked to them stability and compatibility problems.  

Recent efforts to address the known disadvantages of acid kata lysed to decrease and in thermally curing systems them the benefits of photochemical activation Using UV radiation, for example, is reflected in EP 1 92 967. There are sulfonyl derivatives of aromatic aliphatic ketones, especially α-sulfonyl acetophenone compounds, disclosed as being photochemical activatable latent acid catalysts can be used can. These connections are compared to the previous ones knew UV acid catalysts more favorable application properties in particular with regard to influencing the ge hardened layer and storage stability of the binder stems, attributed to. Furthermore, these connections as radical initiators for radical poly merizable binder systems and for hybrid binders systems based on radical and acid-curing Ingredients are used.

However, the compounds known from EP 1 92 967 have the Disadvantage that they are only moderately reactive. For a defi The hardening result is comparatively high performance and / or long exposure times such. In addition, these connections have the aftermath part that their synthesis is relatively complex and with the Ver use of harmless starting materials and solutions medium and the formation of harmful by-products is knotting. Their industrial manufacture and use under Economic aspects and with inclusion Today's environmental and occupational safety issues are therefore prob lematic.

The aim of the invention was therefore to further compounds to find who as radical initiators and as radiation-activatable latent acid catalysts in strah hardenable binder systems based on radika lisch and / or acid-curable components can be used.  

The connections sought should have a higher one Reactivity than conventionally used Ver Show bonds and as easily and easily as possible be accessible.

It has now been found that certain α-substituted Sulfonyl compounds meet these requirements in excellent Way to meet.

These are compounds of the formula I.

with X equal to R³ or NR³R⁴,

wherein

R² R, OR, NR₂
R³ H, R
R⁴ H, R, -CHR¹-SO₂-R² and
R alkyl, cycloalkyl or aryl each having up to 10 carbon atoms, optionally mono- or polysubstituted by OH, halogen, cyano, nitro, alkyl, alkoxy, alkylthio, mono- or bisalkylamino, alkanoyl, alkanoyloxy, alkanoylamido, alkoxycarbonyl, alkylaminocarbonyl , Aryloxy each with up to 6 carbon atoms
means.

It was found that the compounds of formula I by Irradiation with UV light of a wavelength in the range between 200 and 450 nm first free radicals and then each form acidic degradation products according to the reaction environment. Some relies on as photoactivators in binder systems Radically and / or acid-curable components have been proven they surprisingly prove to be significantly more reactive than conventional connections and in particular from EP 1 92 967 known sulfonylacetophenone compounds think.

The invention thus relates to the use of Compounds of formula I as radical-forming photoini tiatoren and / or radiation-activatable latent acid catalysts in binder systems based on radi calically and / or acid-curable components.

The invention furthermore is radiation-hard bare binder systems based on radical and / or acid curable components that are an effective amount at least one compound of formula I as radical bil end photo initiators and / or as radiation activators contain bare latent acid catalysts.

The invention also relates to a method for curing binder systems based on radi Kalisch and / or acid-curable components, where one an effective amount of at least one compound of the formula I and the curing by irradiation with UV light with a wavelength between 200 and 450 nm or by combined irradiation and heating.

Finally, the invention relates to a method for the production of a radiation-hardened coating on a substrate, using a binding agent  system based on radical and / or acid-hard components, containing an effective amount of min least one compound of formula I coated and the Curing by irradiation with UV light of one wavelength between 200 and 450 nm or by combined irradiation oil and heating.

In the α-substituted sulfonyl derivatives of the formula I with the meanings given above it is in essential to known compounds. In Formula I the substituent X in the α-position to the sulfonyl group can be a Hydroxy or an amino group, which in turn itself can be substituted. Accordingly arise the substructures of sub-formulas Ia, Ib and Ic with the meanings given above.

Compounds of sub-formula Ia are due to their structural simplicity and particularly economical Accessibility preferred. But also the connections of the Sub-formulas Ib and Ic are equally good in the sense of the invention can be used.

Compounds of the formula I or Ia to Ic, the β-constant to the sulfonyl group a carbo own nyl group.  

Corresponding compounds are particularly preferred: can be represented by sub-formula Id.

Typical examples of compounds of the formulas I or Ia to Id are about the following:

The compounds benzoyl- (p- tolyl-sulfonyl) -methanol, (m-nitro-benzoyl) - (phenyl- sulfonyl) methanol and benzoyl (p-methoxyphenyl sulfo  nyl) -methanol, especially the compound benzoyl- (p- Tolyl sulfonyl) methanol.

The compounds of formula I in which X is an OH group represents, can be formally as addition products of Sulfinic acids on aldehydes according to the reaction scheme

understand. In practice, they are on this path too easily and with mostly excellent yields accessible. When performing this reaction in counter were from amines or by subsequent implementation the corresponding amino compounds are available. Practical information for performing syntheses for compounds of formula I are, for example, ent removable from:

E. v. Meyer, J. Prakt. Chem. 53, 167 (1901) (Ref. 1),
EP Kohler, M. Reimer, J. Amer. Chem. Soc. 31, 163 (1904) (Ref. 2),
H. Bredereck, E. Bad, Chem. Ber. 87, 128 (1954) (ref. 3),
H. Bredereck, E. Bad, Chem. Ber. 87, 784 (1954) (Ref. 4),
E. Bader, HD Hermann, Chem. Ber. 89, 40 (1955) (Ref. 5),
K. Schank, Chem. Ber. 99, 48 (1966) (ref. 6),
K. Schank, Liebigs Ann. Chem. 716, 87 (1968) (ref. 7).

There are also numerous connotations in the works mentioned characterized in formula I.  

According to the invention, the compounds of formula I very advantageous as radiation activators for curing of binder systems are used. Your special their advantage is that from them by beam Radical exposure can be released NEN as well as that they induced radiation to acidic gap products can be broken down, which then as acid catalysts work. This acid degradation is above that also thermally inducible, so that an additional promotion or sole triggering of this Process by exposure to heat is possible.

According to these multifunctional properties the compounds of formula I are equally one can be used as a radical-forming photo initiator in bandage means systems based on radically curable com components and as radiation-activatable latent acid catalysts in binder systems based on acid curable components as well as in mixed systems, so called hybrid binder systems that side by side contain radical and acid curing components.

The use according to the invention of the compounds of the formula I. as photoactivators in such binder systems he follows together by simply mixing with these binders settlements, if necessary with gentle heating or Adding minor amounts of solvent to the funding homogeneous distribution. The connections of the For mel I are for common applications and processing Processes are sufficiently effective when in the binder systems in a proportion of 0.1 to 20% by weight. Their proportion is preferably between 1 and 10% by weight; be their use in. is particularly expedient and economical a proportion of about 2% by weight, based on the total amount of the binder system.  

Depending on the nature of the substituents R ¹ and R ^{2, the} photochemical activation of the compounds of formula I can be carried out by irradiation with UV light of a wavelength between approximately 200 and 450 nm. Compounds of formula I and in particular of sub-formula Id, in which the substituents R ¹ and R ^{2 are} phenyl or low-substituted phenyl, are particularly effective primarily in the deep to medium UV range, for example between 200 and 300 nm. By adding in longer-wave areas absorbing co-sensitizers of a known type, such as aromatic ketones, the sensitivity in the near UV range can be increased if necessary or desired.

Radiation-curable binder systems based on radi Kalisch and / or acid-curable components in which the Compounds of formula I according to the invention as radical forming photo initiators and / or radiation activatable latent acid catalysts can be used known per se.

Under a radiation-curable binder system The basis of radically curable components is becoming more common as a mixture understood that at least one ethy Lenically unsaturated, free radical photopolymer sizable connection and, if appropriate, other conventional ones Contains additives. As radically polymerizable Components are practically all materials that olefi nisch unsaturated double bonds, suitable. This can in particular monomers, oligomers and poly mere with at least one each or expediently with several unsaturated functions from acrylate or Be vinyl type. Appropriate materials are the subject man in great abundance. Examples of such a verb are acrylic compounds, especially acrylates from aliphatic and aromatic mono- or polyhydroxyver bonds such as (meth) acrylic acid including its  Salts and amides, (meth) acrylonitrile, (methy) acrylic acid alkyl ester, hydroxyethyl (meth) acrylate, vinyl (meth) acrylic lat, ethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, trimethylolpropane di (meth) acrylate), pentaerythritol tri (meth) acrylate, further vinyl compounds such as Vinyl chloride, vinylidene chloride, styrene, divinylbenzene, N- Vinyl pyrrolidone, N-vinyl carbazole. Examples of higher moles Kular and polymeric binder components are about acry gated polyester, acrylate, epoxy, urethane, polyamide and silicone resins. Radiation-curable bin are predominant mixtures of several of the listed below molecular and high molecular weight unsaturated components ten.

Acid-curable binder systems that also Area of application of the compounds of the invention Formula I represent all those systems that at least one acid-catalyzed polycondensation Component included. These are mainly synthetic resin Melamine or urea based materials that also can be modified in many ways. The subject these materials are familiar; they will be large quantities and for a wide variety of uses industrially modified in their material properties produced. A typical example of a melamine The base material is about hexamethoxymethylmelamine. About that In addition, the acid-curable binder systems can be any other components in different proportions contained in the technology of aminoplast Plastics are common, for example alkyd, phenol, Polyester, acrylic and polyvinyl resins or their mixtures.

The compounds of formula I are suitable as radiation Activatable curing catalysts, especially for Hybrid binder systems that acid catalyzed polycon densable and free-radically polymerizable An  parts included. According to the invention, you can do this purely photochemically and appropriately combined photo be activated chemically-thermally, being the same measure act as radical and acid generators and so with practically simultaneous hardening of the different Effect hybrid system components. As an acid-curable com Components for such hybrid systems all come up already mentioned materials in question, materials that is, thermally, for example by polycondensation tion or polyaddition, but not radical ver can be networked. Examples include acid curable melamine resins as well as polyurethane or polyester forming reactive resins. As radically polymerizable Components are practically all of the mate mentioned above rialien, the olefinically unsaturated double bonds point, suitable. In such hybrid binder systems The proportion of acid-curable and radical can polymerizable components in broad areas, such as can each be varied between 10 and 90% by weight.

The radiation-curable binder systems can also be used in Form aqueous dispersions are present, their water content after coating, usually by a short Heating is removed.

The with the compounds of formula I as photoactivators curable binder systems, whether purely radical polymerizable, purely acid-curable or on hybrid Basis, can be in their qualitative as well as quantitative Compositions can be varied over a wide range and in particular, they can also contain other components and Additives included. Appropriately, the Proportion of reactive components not less than 10% by weight stride. As further components and additives in the quantities appropriate and usual for the respective purpose inorganic and organic pigments, dyes,  Fillers, leveling agents, surface-active agents, Matting agents, plasticizers, solvents, dispersants auxiliaries, other binders and resins, other photo initiators, spectral sensitizers and initiators known type, further thermo or photoreactive radical starter as well as cation or acid-forming catalysts be included.

The coating of substrates, mostly flat Objects made with such binder systems in a manner known per se. Appropriate coating technologies and devices are familiar to the expert fig and are commonly available.

The application extends primarily to the Generation of thin layers such as paint coatings on all common materials and Carriers. These can primarily be paper, wood, tex tile support, plastic and metal. An important application The area of application is also the drying or hardening of pressure inks and screen printing materials, the latter before moves in the surface coating or design of for example cans, tubes and metal caps be used.

The compounds of formula I according to the invention contain tendency binder systems and the so produced Coatings can be exposed to radiation gie, especially from the UV wavelength range between 200 and 450 nm can be hardened. Can be used as beam sources the usual mercury vapor high pressure, medium pressure or - Use low pressure lamps as well as xenon and tungsten lamps be det.  

In certain cases, especially with acid-curable or Hybrid binder systems, it is useful to cure by simultaneous or subsequent supply of To promote thermal energy. The additional thermal acti Crossing takes place in the for acid catalyzed heat curing systems usual temperature range. This lies about between 80 and 150 ° C, preferably between 100 and 120 ° C.

A particularly favorable property of the connections of the Formula I here is that by carefully choosing the Substi did their photochemical and thermal activity vari ized and coordinated with each other and the respective sensi balance can be controlled in a targeted manner.

Hardening can be both discontinuous and continuous done nuously. The radiation duration depends on the Type of implementation, the type and amount of used polymerizable materials, of type and concentration tion of the photo activators used and the intensi the light source. When curing radiation from Coatings, it is usually in the range of less Seconds to minutes. The duration of a possibly expedient Additional heat treatment depends on the temperature and binder system until fully hardened in the range of minutes to a few hours.

The compounds of formula I have compared edible radiation activators, especially those from EP 1 92 967 known α-sulfonylacetophenones, the particular their unexpected advantage that under compar application and processing conditions too clear lead to higher layer hardness. Determine for the achievement The specified layer hardness is shorter radiation times required.  

Furthermore, they are the known radiation activatable and thermal acid catalysts related to the bearings The stability of the binder systems thus added increases superior. Nor do they show any inclination, that is the case end product, especially to yellow.

The simple, problem-free accessibility of the connections Formula I and its excellent application technology Properties make them particularly valuable for practical use table use.  

Examples A. Preparation of compounds of formula I.

The establishment and characterization of connections gene of formula I according to Table 1 below followed after in the cited references given regulations or analogously. All herge Connections made correct elementarana read.

Analog regulation (connection No. 31)

A mixture of 7.6 g (50 mmol) phenylglyoxalhy and 4.6 g (50 mmol) of aniline in 50 ml of THF Stirred for 2 hours at room temperature. Then were 7.8 g (50 mmol) of toluenesulfinic acid were added and white stirred for another 16 hours. The fancy low blow was suction filtered, washed with ether and off Recrystallized toluene. 9.9 g (27 mmol = 54% d. Th.) On benzoyl- (phenylamino) - (p-tolyl- obtained sulfonyl) methane of melting point 131.5 ° C.

Table 1

B. Comparative application test

In a paint system (hybrid binder system), consisting out

72 parts by weight of an acrylated, aromatic epoxy resin (Laromer® EA 81 from BASF),
18 parts by weight of hexanediol diacrylate,
10 parts by weight of hexamethoxymethylmelamine (Cymel® 303 from Dyno Cyanamid),

2% of the ver binding of formula I (compound no. 14) or 2% the reference substance ("DTA", from EP 1 92 967) in Form 10% solutions evenly in n-butanol touched.

The ready-to-use paint samples were then opened Glass plates (10 cm × 10 cm) in a layer thickness of 80 µm and applied to remove the solution flashed off at room temperature for 10 min.

After flashing the coated glass plates in a UV laboratory dryer (type BE 22 der Beltron) with belt speeds of 2.5 m / min up to 40 m / min (exposure times of 1.5 s / m up to 24 s / m) at a distance of about 10 cm below a medium pressure mercury lamp with an output of 80 W / cm passed.

After the UV radiation, the coated ones Plates in a laboratory drying cabinet for 30 minutes cured at 120 ° C. After curing and ab the surface was cooled sorically determined and about 20 hours after on was used as a measure of the hardening result Pendulum hardness determined according to König (DIN 53157).

Table 2 and Fig. 1 show the results.

Table 2

It turns out that over the entire hardening area speed range with the Ver bond get significantly harder coatings be considered with the reference substance.

For the production of coatings with a certain pendulum hardness (e.g. of 170 sec) can activation with the verb according to the invention cure faster than with the Ver same substance (e.g. at 6 m / min instead of 4 m / min).

Claims (6)

1. Radiation-curable binder systems based on free-radical and / or acid-curable components, characterized in that they contain an effective amount of at least one compound of the formula I. with X equal to OR³ or NR³R⁴, in which means R² R, OR, NR₂
R³ H, R
R⁴ H, R, -CHR¹-SO₂-R² and
R alkyl, cycloalkyl or aryl each having up to 10 carbon atoms, optionally mono- or polysubstituted by OH, halogen, cyano, nitro, alkyl, alkoxy, alkylthio, mono- or bisalkylamino, alkanoyl, alkanoyloxy, alkanoylamido, alkoxycarbonyl, alkylaminocarbonyl , Aryloxy, each with up to 6 carbon atoms, as radical-forming photoinitiators and / or radiation-activatable latent acid catalysts. 2. Binder systems according to claim 1, characterized records that it 0.1 to 20 wt.%, Preferably 1 to 10% by weight of compound (s) of the formula I contain. 3. Use of compounds of formula I as radical forming photo initiators and / or radiation activators bare latent acid catalysts in binders systems based on radical and / or acid curable components. 4. Process for hardening binder systems Basis of radical and / or acid-curable compo nenten, characterized in that one this effective amount of at least one compound of For mel I adds and the curing by irradiation with UV light with a wavelength between 200 and 450 nm or by combined irradiation and heating. 5. The method according to claim 4, characterized in that 0.1 to 20% by weight, preferably 1 to 10% by weight, of compound (s) of formula I.   6. Process for producing a radiation-cured Coating on a substrate, characterized records that this with a binder System coated according to claim 1 or 2 and the Hardening by exposure to UV light from a wave length between 200 and 450 nm or by combined irradiation and heating.