WO1995007304A1

WO1995007304A1 - Polymerizable composition including olefinically unsaturated compounds activated by air

Info

Publication number: WO1995007304A1
Application number: PCT/EP1994/002874
Authority: WO
Inventors: Thomas Huver; Petra Nowak; Carsten Friese; Frank Bergmann
Original assignee: Henkel Kommanditgesellschaft Auf Aktien
Priority date: 1993-09-08
Filing date: 1994-08-31
Publication date: 1995-03-16
Also published as: DE4330354A1

Abstract

The invention concerns particular furanones suitable for use as initiators in the radical-induced polymerization of unsaturated compounds in the presence of air, which makes controlled polymerization possible with a nitrogen-free initiator system. Thus adhesives and sealing, coating and moulding compounds, for example, remain stable when stored for a period, sufficient for practical applications, of several months, and will subsequently cure within an hour at room temperature simply on exposure to air.

Description

"Polymerizable composition with olefinically unsaturated compounds that can be activated by the entry of air"

The invention relates to a composition which contains a free-radically polymerizable olefinically unsaturated compound which can be activated by air. The invention also relates to their use as an adhesive and sealing compound and to their use for coating and producing plastic moldings. Such compositions polymerize radically at room temperature.

For hardening by peroxides or hydroperoxides, olefinically unsaturated systems require selected starters or activator systems, in particular, if the reaction is to be triggered at low temperatures, for example at room temperature or only slightly elevated temperatures. It is known, for example, that selected tertiary amine compounds with partially aromatic substitution on the N atom have such an activator function. Known activators for initiating the polymerization, for example using dibenzoyl peroxide, are in particular dimethylaniline and dimethyl-p-toluidine. The application DE 40 00 776 describes hydrazone compounds as starters or main components in the starter system for the curing of olefinically unsaturated compounds by radical polymerization by means of ambient air.

DE 41 23 194 describes a polymerizable composition which can be activated by air and which contains an olefinically unsaturated compound and a hydrazone. In addition, the composition can also contain a metal compound, a reducing agent and - depending on the area of use - a thickener and adhesion promoter. The composition is suitable as an adhesive and as a sealing, coating and molding compound.

The compositions mentioned contain initiator systems with N compounds. This can be associated with disadvantages in special cases, e.g. If tertiary aromatic amines are to be assessed as toxicologically harmful, the frequently used N, N-dimethyl-p-toluidine is a T substance in the sense of the Hazardous Substances Ordinance. The toxicology of the hydrazone used as the initiator has also not yet been sufficiently investigated.

N-free initiator systems are also known, for example metal compounds which are at least partially soluble in the composition and are derived from polyvalent metals. Such metal compounds of such metals which are sufficiently soluble in organic solvents and / or in binders have long been known as so-called drying agents for air drying paints, varnishes and the like based on unsaturated oils. Sufficiently oil-soluble compounds of such transition metals which are capable of occurring in several valence levels are particularly suitable here. The ability to accelerate hardening is with the individual components different degrees. Compounds of cobalt and / or manganese are primarily used, but iron also accelerates hardening. In addition, and in particular in combination with these highly effective metallic components, comparable compounds of other metals can be used, which may also be capable of forming several valence levels. A detailed description of such systems can be found, for example, in "Ullmann, Encyclopedia of Industrial Chemistry", 4th edition, volume 23 (1983), 421 to 424.

Such metal compounds have the disadvantage that, in combination with drying oils as N-free initiator systems, they do not have any practical starters for free-radical curing, snow-curing systems such as e.g. Deliver reaction adhesives.

According to E.P. Kohler is known that furanones form hydroperoxides on contact with oxygen [JA CS, 58 (1936), pp. 264-267].

The object of the invention is to develop new possibilities for the practical use of such starters or activators and activator systems which are free of N compounds, using the previously known knowledge described. The activators should - in a mixture with free-radically polymerizable substances or mixtures of substances in practice - be inherently capable of being activated by access to ambient air. In preferred embodiments, this activation should already occur at room temperature; if necessary, a temperature increase is provided. A particularly important aspect of the invention is directed to multicomponent systems of the type mentioned, which simply by entering ambient air at room temperature to trigger the start reaction of a radical polymerization of unsaturated Systems are capable, with time-controlled curing and predeterminable pot life. In an important embodiment, the invention seeks to create, in particular, one-component, storage-stable systems which, in their application form, are malleable, in particular pasty to flowable and have a pot life sufficient for processing, but then harden in a dimensionally stable manner by the simple action of the ambient air.

The solution according to the invention can be found in the patent claims. It is based on the knowledge that certain furanones can be used as initiator components for the radical polymerization of unsaturated compounds when exposed to air. If radical formers such as oxygen, peroxides, hydroperoxides etc. are switched off as far as possible, the composition is also stable in storage, i.e. For a period of at least 2, preferably at least 12 months, no polymerization takes place at room temperature, recognizable by the practically unchanged viscosity. At least it is still useful for the respective application. However, by simply admitting air at ambient temperature or elevated temperature, the polymerization is initiated and completed within an acceptable time. It is thus possible to produce one-component adhesives, sealing compounds, coating compounds and molding compounds and to store them practically without loss of activity. The open period of the system required for the shaping processing can largely be freely determined. The compositions according to the invention are therefore of considerable practical importance in many fields of application technology.

The invention therefore relates to a storage-stable composition which contains a free-radically polymerizable olefinically unsaturated compound and a furanone of the following general formula

in which

X is an inert substituent that does not form a chemical bond during manufacture, storage or use, and

Rl and R2 are independently H or an aromatic or aliphatic group with up to 40 C atoms, which may also contain the inert substituent X, and where the C-C double bond of the five-membered ring can also be hydrogenated.

The "olefinically unsaturated compounds" include all acyclic and cycTic aliphatic hydrocarbons with one or more reactive double bonds in the molecule. In particular, this includes all vinyl monomers, but moreover in particular also acrylic acid, methacrylic acid, styrene and butadiene and their derivatives. All or part of them can also be present in the form of reactive preformed oligomer and / or polymer compounds. Monomers or oligomers with free carboxylic acid groups are particularly preferred.

The furanone compounds according to the invention are mono-, di- or tri-substituted. The trisubstituted compounds are preferred. The radicals R 1 and R 2 can be linear and / or cyclic alkyl groups with up to 40 carbon atoms, in particular with 1 to 8 carbon atoms. Be atoms, but aromatic groups are preferable. The R 1 and R 2 groups and the phenyl group can be unsubstituted or substituted. It should be taken into account here that the substitution of these radicals can have a certain influence on the reactivity of the activator system, especially in the case of phenyl groups. Appropriate substitution of the phenyl radical can thus accelerate the reaction by providing known electron-donating substituents on this phenyl radical. Electron-donating and thus reaction-accelerating substituents are, for example, alkyl, alkoxy and / or halogen substituents on the phenyl radical, conversely strong electron-withdrawing substituents of the type of the -NO2 group have a slowing effect on the course of the reaction.

Of course, the phenyl ring can also contain other substituents if they do not interfere with the starter function.

The double bond in the five-membered ring of the formula I can also be hydrogenated.

The preferred furanone is the substituted or unsubstituted 2,4,5-tripheny1-furanone-3.

The purity of the composition is of particular importance for the targeted polymerization, in particular for storage. The oxygen can be removed by degassing, e.g. with the help of ultrasound, vacuum or by chemical means.

It is known that olefins and other unsaturated compounds, in particular polymerizable monomers, have to be stabilized for their storage. The following basic types of reaction are assumed: 1. Stabilization against O2 by adding antioxidants and 2. Stabilization against radicals by adding radical inhibitors. Typical chemical stabilizer components are listed below from the general chemical knowledge, it being indicated in brackets behind the specific compound which mechanism the stabilizer is to be assigned to: pyrogallol (1), O2-inhibited acrylates (1), hydroquinone (1,2), hydroquinone monomethyl ether (1,2), butylated hydroxytoluene (2) and phenothiazine (2). Deoxygenators of the triphenylphosphine type and iodine solutions are of particular importance for stabilizing the system against undesired premature reaction. Their amount is measured according to the intended use. It can easily be determined in individual cases by professional considerations and / or by preliminary tests. In general, the weight fraction of stabilizers is at most 5% by weight, preferably 0.01 to 1% by weight, based on the total composition. Too high an amount delays the desired polymerization when air is admitted.

The composition according to the invention preferably also contains an addition of metal compounds which can occur in several valence levels. Selected representatives of the transition metals can be particularly active here. The respective selection of the metal can, among other things, have a speed-determining character for initiating the polymerization. Components that are highly active at room temperature derive e.g. B. from copper, cobalt, vanadium and / or manganese. Compounds of iron are of particular importance and good reaction acceleration. Iron, cobalt and / or manganese compounds are particularly suitable for working at room temperature, which is particularly advantageous for many areas of application, optionally in a mixture with other metallic components such as compounds of lead, cerium, calcium, barium, zinc and / or zirconium. It can be relevant here Reference to specialist literature, compare, for example, the cited publication in "Ullmann" loc. Cit. And the previous literature cited there.

The metals concerned here are used in the form of such compounds that they are at least partially soluble in the overall system. Both soap-like metal compounds and other types, in particular complexes bonded to organic radicals, can be considered. Typical examples of working in the sense of the action according to the invention is the use of corresponding metal naphthenates or metal acetylacetonates. If there is sufficient solubility of inorganic salts in the system, the use of such inorganic systems is also possible. A typical example of this is iron chloride, which shows a significantly accelerating effect when used in the system according to the invention.

It may be appropriate to use the metal compounds in each case in a low valence level of the metal - for example as cobalt (II) or manganese (II). In other cases, the use of the metal compound in the higher valence level of the metal is also suitable. For example, iron can also be used in the form of Fe3 ⁺ compounds.

The activator components of the type concerned, which are optionally used according to the invention, are the diverse mixture components with a reducing effect, as are used in conventional redox systems to initiate polymerization. Reference is made to the relevant extensive literature, for example W. Kern, Makromol. Chem. 1, 249 (1947) and C. Srna, Angew. macromol. Chem. 9, 165 (1969) as well as the general specialist knowledge, as it z. B. is described in Houben Weyl "Methods of Organic Chemistry" Volume 14/1, 263 to 297. The class of alpha-hydroxy ketones, for example with their representatives butyroin, benzoin or acetoin, has proven to be particularly active here. However, the teaching of the invention is in no way limited to this. It is essential that this class of substances can take on an important reaction-accelerating function in the activator systems used according to the invention, but that their use is not mandatory.

Starter or activator systems composed of the main components described here, furanone compound, at least partially soluble metallic dry substance and / or, if desired, accelerators used, are able, after taking up ambient air, to initiate all the radically polymerizable olefinically unsaturated systems which have hitherto been associated with the various, especially N-containing starter systems are used.

To define the further constituents of the composition according to the invention, reference can be made to the extensive information in the relevant literature which deals with the production and processing of systems which are based on olefinically unsaturated compounds which can be polymerized by free radicals. An extraordinarily large number of fabric systems of this type are available in the professional world today, and their properties are tailored to the respective application. Olefinically unsaturated reactive systems can be constructed on the basis of selected free-radically polymerizable ethylenically unsaturated compounds or on the basis of mixtures of several types of such compounds. The ethylenically unsaturated polymerizable components can be monofunctional compounds and / or multifunctional reactive components. In order to achieve rapid polymerization with preferably contact with the air, a composition should preferably be selected which has an initial viscosity of at least about 30 to 100 mPas, preferably of at least about 200 or 300 mPas. A particularly reliable start of the polymerization reaction can be expected in systems whose initial viscosity is at least about 500 mPas and in particular at least about 1000 mPas. All of these viscosity values are determined as Brookfield viscosity. Commercially available adhesive systems are known to have viscosities of at least approximately 3000 mPas and in particular viscosity values in the range up to approximately 10000 mPas. Materials of this type are understandably well suited for processing in the sense of the invention. The invention is in no way restricted to this. Much thinner-viscous systems, for example paintable coating systems - which are used in particular as solvent-free systems - are suitable for the mechanism of triggering the reaction described here, provided that the described minimum values for the initial viscosity of the material to be shaped are observed. The same applies to other areas of application, for example for the production of molded plastic parts based on styrene / unsaturated polyester resins.

The required initial viscosity values can in particular be set by mixtures of substances which have a sufficient content of oligomeric and / or polymeric components, optionally in admixture with low molecular weight unsaturated components which are liquid at room temperature, such as (meth) acrylates. Correspondingly viscous masses can, however, also consist exclusively of precondensates of suitable flowability. In particular, the extensive knowledge of the specialist world applies to such ethylenically unsaturated substance-curable mixtures curable by radical polymerization. The multicomponent mixtures to be used according to the invention are generally in the form of one-component systems which are kept protected from the ingress of air until use. However, they can also be provided as multi-component systems. The components are then mixed with one another for practical use of the system. The open pot life of the system can be regulated by suitable selection and adaptation of the main components of the activator system, so that here too the triggering of the start reaction and thus ultimately the curing of the system under ambient conditions in the air is possible. In one embodiment of the invention, the multicomponent mixtures concerned consisting of the activator system and polymerizable components and also non-reactive two-component systems in the presence of air are present. It is then particularly preferred to separate the main components of the activator systems used according to the invention from one another in such a way that the furanone compound is kept separate from the metal compounds. Both components can then generally contain ethylenically unsaturated reactive mass. All that is required for processing is the mixing of these two separately kept components, the shaping during the open pot life of the system and the entry of the ambient air.

The invention allows the compilation of optimized material mixtures. In compliance with the laws of the invention, soluble and / or insoluble fillers, elasticizers, thickeners, thixotropic agents, pigments, adhesion promoters and the like can also be used without the functionality of the starter system according to the invention being endangered. The prerequisite for this is, of course, that the choice of the auxiliary and fillers ensures that interference in the interaction of the starter components is excluded. General chemical knowledge applies to this. In the multi-component mixtures of the invention, the starter mixtures preferably make up no more than about 15% by weight and in particular no more than about 10% by weight, in each case based on the weight of the overall system. Depending on the activity of the components used, the weight of the starter mixture can be reduced very greatly and, for example, can be reduced to the range of about 0.1% by weight or at least about 0.5% by weight. Amounts of the starter system of at least about 1% by weight, preferably up to about 10% by weight, can be particularly suitable. All of this information relates on the one hand to the total weight of the composition according to the invention and the total weight of the three main components of the starter system.

The three aforementioned components of the starter system can preferably be used in the following proportions - in% by weight, based on the overall system: furanone compounds: at least about 0.1% by weight, expediently 0.5 to 12% by weight .-%, preferably 1 to 8 wt .-% soluble Metallverbin¬ connection: 0 to 5, preferably 0 to 3, in particular 0.005 to 3 wt .-%. Deoxygenator: 0 to 5% by weight, preferably 0.01 to 1% by weight.

Mixtures of oligomer and / or polymer substances, together with ethylenically unsaturated monomers of low molecular weight, are used as mixtures of free-radically polymerizable compositions which are versatile and customary in practice. The mixture components of higher molecular weight are often at least partially soluble in the monomers. Mixtures of this type are particularly suitable for processing within the meaning of the invention. The content of monomers - for example of the (meth) acrylate type, the optionally substituted styrene and / or the acrylonitrile - is generally at least 10% by weight, preferably at least about 20% by weight and can make up at least about 40% by weight in many applications. % By weight here in each case based on the ready-to-react finished mixture. The monomer component can be the component which is by far the most significant by weight, so that, for example, 60 to 80% by weight of the total mass is formed by the low molecular weight monomer. However, as previously shown, care must be taken to ensure that the use of a sufficient amount of higher molecular weight compounds and / or other thickening agents ensures the at least slightly increased initial viscosity of the substance mixtures for reliable reaction initiation in the event of air access.

These application conditions are guaranteed in any case in characteristic application examples which fall within the scope of the invention as preferred embodiments. Without claiming to be complete, the following examples may be mentioned here: aerobically curing sealant and adhesive systems, brushable agents for surface coating with polymerizable, in particular solvent-free, paints and coatings in the sense of brushable air-drying paint systems, and the production of moldings with reaction initiation by the action of ambient air , for example based on styrene / unsaturated polyester resins.

B e i s p i e l e

For the following examples, the ethylenically unsaturated compounds (hereinafter also referred to as monomers) were freed of any inhibitors present and, if possible, purified by distillation. In the case of volatile, non-distillable monomers, dissolved oxygen was removed by evacuation and subsequent passage of N2 for several hours. The monomers were stored and removed under inert gas (2 or Ar).

The furanones were produced according to regulations known from the literature (see, for example, Kohler et al. JACS 58 _ι 264/1936) and stored and removed under inert gas.

To determine the gelling time, 100 mg of adhesive are applied to an Fe sheet in the form of drops and the time in which a skin has formed or the liquid adhesive has changed to a gel state is determined visually or by means of a preparation needle.

To determine the curing time of the polymerizable multi-component mixture, 100 mg of the mixture formulated under inert gas are exposed to the ambient air in a watch glass. The mixture is cured when the entire amount of sample has been converted into a thermoplastic or thermoset solid.

For bonding, test specimens according to DIN 53281 are provided with the polymerizable mixture and exposed to the ambient air for a defined time (90 to 600 seconds) before joining.

The tensile shear tests are carried out in accordance with DIN 53283 on overlapped (250 mm ² ) specimens. The examples were carried out according to the following general procedures:

The monomer was placed in a multi-necked flask filled with N 2 and the thickener was dissolved therein, or a mixture was used immediately. The metal compound, the activator, the inhibiting stabilizer and an adhesion promoter were then added, again taking care to exclude oxygen. The homogenized mixture was cooled to -196 ° C., the flask was evacuated to 0.5 torr and then warmed to room temperature. By repeating this freeze / thaw cycle several times, residual oxygen was removed from the system. The furanone compound was then added and again degassed as indicated above. The mixture was stored under inert gas.

The examples show the usability of the new initiator system for free-radical polymerization under practical conditions.

The compositions consisted of the following components (in parts by weight) and had the following properties:

Example: 1 2

1. Components •

Methyl methacrylate 50 50 50

2,4,5-tripheny1-furanone-3 6 6 6

Polyacrylate 40 40 40

Metal compound - Cu-Naph-Felll- thenat acetyl-acetonat

1 1.3

Reducing agent - - Butyroin 2

Adhesion promoter methacryl oyloxy ethyl phosphate

0.5

2. Properties

Setting time [min] 20 13 38

Hardening time [min] 60 60 85

Tensile shear strength [N / mm ² ]

Fe / Fe 12.6

PVC / PVC 2.9 Examples

1. Components

Monomer, parts by weight MMA 50 MMA 50 HPMA 80 HPMA 80

2,4,5-triphenyl-furanone-3 3.6 3.6 6 6

Polyacrylate 12.5 12.5 - -

Polyurethane methacrylate - - 20 20

Metal compound Co (II) acetyl - - Fe (III) acetyl acetonate 0.05 acetonate 1

Reducing agent

Stabilizer - - NaI, 0.05 NaI 0.05

Methacryloyloxyethyl phosphate 0.3 0.3 0.5 0.5

2. Properties gel time [min] 30 30 42 6 curing time [min] 85 85 60 tens

Abbreviations

MMA = methyl methacrylate

HPMA = hydroxypropyl methacrylate

Polyurethane methacrylate = reaction product from

1 mole of polypropylene glycol

(MW 2000)

2 mol 4,4'-diisocyanatodiphenylmethane (MDI)

2 mol hydroxyethyl methacrylate

Claims

claims

1. Air-activatable polymerizable composition which contains a free-radically polymerizable olefinically unsaturated compound and a furanone of the following general formula

in which

X is an inert substituent, which is neither in the

Manufacturing still enters into a chemical bond during storage or use, and

R1 and R2 independently of one another are H, an aromatic or aliphatic group with up to 40 C atoms, which can likewise contain the inert substituent X, and the C-C double bond of the five-membered ring can also be hydrogenated.

2. Composition according to claim 1, characterized in that mono- and / or polyfunctionally olefinically unsaturated polymerizable compounds and preferably acrylic and / or methacrylic acid, acrylate and / or methacrylate compounds or systems, styrene or styrene Derivatives and / or components containing acrylonitrile are used, which may also be present in whole or in part in the form of reactive preformed oligomer and / or polymer compounds.

3. Composition according to claim 1, characterized in that the furanone is a substituted or unsubstituted 2,4,5-triphenyl-furanone-3.

4. Composition according to claim 1, 2 or 3, characterized by an addition of stabilizers against radicals and 02-action, preferably triphenylphosphine and iodine.

5. Composition according to at least one of claims 1 to 4, characterized by an addition of metal compounds, which can occur in several valence levels, as an activator, in particular Fe, Co, Mn or V.

6. The composition according to at least one of claims 1 to 5, characterized in that it can be shaped and has a viscosity of at least 100, preferably 300, in particular 500 mPa-s (Brookfield).

7. Composition according to at least one of claims 1 to 6, characterized by the following parts by weight in percent by weight, based on the total composition:

at least 20, preferably at least 40% by weight of olefinically unsaturated compound,

at least 0.1, preferably 0.5 to 12 and in particular 1 to 8% by weight of furanone,

0 to 5, preferably 0.01 to 1% by weight of stabilizer,

- 0 to 5, preferably 0 to 3 and in particular 0.005 to 3% by weight of metal compound and

- 0 to 80, preferably 5 to 50 wt .-% of auxiliaries according to the use of the composition, for example fillers, pigments, thickeners, adhesion promoters, reducing agents and elasticizing agents.

8. Use of the composition according to at least one of claims 1 to 7 as an adhesive and sealing compound which bind by the action of ambient air and in particular at ambient temperature, the olefinic compound preferably being an acrylate or a methacrylate compound and at least partially therein, a polymer is dissolved, so that the viscosity above 500 mPa · s, in particular in Be¬ range of approximately 3,000 to 10,000 mPa ^«s.

9. Use of the composition according to at least one of claims 1 to 7 for surface coating and production of plastic molded parts which cure by the action of ambient air and in particular at ambient temperature.

10. Use of the furanone according to claim 1 or 3 as an initiator component for the radical polymerization of unsaturated compounds.

11. Initiator system for the radical polymerization of unsaturated compounds in the presence of atmospheric oxygen, containing the furanone according to claim 1 or 3 and the metal compound according to claim 5.